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An Integrated Approach

DEVELOPING INDUSTRIALCHEMICAL PROCESSan

Copyright © 2002 by CRC Press LLC

CRC PR ESSBoca Raton London New York Washington, D.C.

Joseph Mizrahi

An Integrated Approach

DEVELOPING INDUSTRIALCHEMICAL PROCESSan


This book contains information obtained from authentic and highly regarded sources. Reprinted materialis quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonableefforts have been made to publish reliable data and information, but the author and the publisher cannotassume responsibility for the validity of all materials or for the consequences of their use.

Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronicor mechanical, including photocopying, microfilming, and recording, or by any information storage orretrieval system, without prior permission in writing from the publisher.

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Product or corporate names may be trademarks or registered trademarks, and areused only for identification and explanation, without intent to infringe.

Visit the CRC Press Web site at www.crcpress.com

© 2002 by CRC Press LLC St. Lucie Press is an imprint of CRC Press LLC

No claim to original U.S. Government worksInternational Standard Book Number 0-8493-1360-0

Printed in the United States of America 1 2 3 4 5 6 7 8 9 0Printed on acid-free paper

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Catalog record is available from the Library of Congress

1360_frame_FM Page 4 Friday, May 3, 2002 12:48 PM


www.crcpress.com

Preface

This book presents a detailed discussion of the issues that have to beaddressed, in most cases, in the development and the first implementationof a novel industrial chemical process.

These issues start with the “whys” and “wheres,” then address theworking organization and all the different steps, activities, and reviews inthe process development program, and finally in the implementation, design,construction, and start-up of a new plant.

Why is such book needed at all?

This specific field of activity is constantly occupying many thousands ofmanagers, scientists, engineers, chemists, specialists, economists, and tech-nicians. These professionals work in industrial corporations, research orga-nizations, universities, engineering companies, equipment suppliers, statu-tory public functions, to name a few, in many countries around the world.The result of their activity has been hundreds of new processes and newplants in the chemical industry every year.

Nevertheless, at present, there seem to be no recognized professionalstandards, no generally accepted written procedures, or even a book cover-ing this professional field. Quite different working practices are implementedin different corporations and in different countries. Thus, any professionalwho encounters some of these issues for the first time in his job can onlyrely on the direct teaching of his boss and colleagues. And in that lotterysome have more luck than others. Strangely enough, up until now, the know-how in this important professional sector has been transmitted only by“apprenticeship.”

Somehow, novel processes have been finally developed and used in newplants that have been built and operated, most of them successful. But, onthe other hand, many case stories are widely spread in the profession aboutall the associated problems, serious waste of time and resources, start-uptroubles, and occasionally complete failures.

These problems have been generally attributed to personal errors inspecific situations, possibly to the individualistic characters of the inventorsand promoters, and to the opportunistic demand for quick results in newprocesses. Such explanations could only be true for the initiation stage

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(possibly 5% of the efforts invested), but cannot hold for all the developmentand implementation work. So, a systematic study of the common aspectsto most projects can be instructive.

This book is intended primarily for those professionals who are alreadyon the job in real life, to help them, hopefully, to do a better and more efficientjob, to be happier by understanding more about what is going on aroundthem, and to reduce the frustrations associated with this line of work. It isassumed that the readers will be graduates with some professional experi-ence, who have access to all the textbooks, handbooks, and publicationsavailable, to Chemical Abstracts and to the Internet, and who know how touse these. So, this book will not be competing with these sources and willnot copy what is readily available. At most, it will refer the readers to themore useful sources, in this author’s opinion. The suppliers of commercialservices have essential contributions to such projects, and the general issuesconnected with the selection of such suppliers are discussed, but no partic-ular reference is given as far as possible. The other references direct thereaders, who may be interested in any of the example cases mentioned, tomore detailed sources.

Also, in this book, with due apologies to the chemists, a chemical processdoes include any physical or mechanical transformation or separation whichis necessary to obtain the final products.

On the face of it, the development and implementation of a new chemicalprocess may appear to be a matter of chemistry, materials, equipment, con-trol, etc., but it should be recognized that this is a very complex endeavor,and its success depends, in fact, mostly on the interactions and organizationof many different people in various positions.

In each such project, hundreds of professionals are concerned, full-timeor part-time, with the research organization, the various functions in thecorporation, the engineering company, the equipment suppliers, patentattorneys, specialist consultants, and civil servants with statutory functions.These professionals are mostly chemical engineers, but all the related pro-fessions are also involved: managers (in particular in finance, production,and marketing), different fields of engineers, research and analytical chem-ists, various specialists, patent attorneys, lawyers, economists, and support-ing technicians.

The first need in a new project organization is to establish a commoncommunication and reference system in which every participant in theproject will understand the point of view, the priorities, and the “jargon” ofthe others. This aim can require both patience and goodwill from everyoneconcerned and should be motivated by the example of the management.

It is hoped that this book can be used for such purposes. The author hasbeen occupied in this field of activity all of his professional life in manydifferent positions. He strongly believes that a project involving the devel-opment and implementation of a new chemical process can be done betterand more efficiently if:



• All the issues and all the interactions were discussed and understoodfrom the beginning by all the participants

• The limits of responsibility were clearly defined• A proper organizational structure and adequate programs were used

The detailed recommendations in this book can be readily integrated,without any contradiction or competition, with the latest trends in corporateresearch and development (R&D) management procedure, such as the “StageGate” system and similar tools, which recently have been introduced inmany large corporations. These detailed recommendations can assist the“Gate Keepers” in defining the “deliverables” and “criteria” to be achievedin the next “Stage.”

All the engineers, scientists, and managers concerned with the develop-ment of a novel industrial chemical process, and/or with the implementa-tion, design, construction, and start-up of a plant based on this process, canuse this book to assist them in their work. The book will give them a generaloverview of all the issues ahead, and also provide them with checklists todraw up their own working programs, or at least understand the logic ofthe instructions given to them by their boss.

Friends with experience have remarked that the scope of this book mayappear to be very complex and its “message” may be confusing for rapidreaders sampling here and there. Therefore, it was decided to add at the endof each chapter a short recapitulation of the issues that can be worth anadditional thought and possibly further reading or discussion.

At least, the core team of a project would benefit from a systematic study.Evidently, not everyone would be interested in all issues at one specific time,but it is nice to know that they can come back and consider more intensivelyany pertinent issue whenever they might face the need. Professionals witha few years of experience in this field, who may recognize some of the issuesdiscussed from personal exposure, should benefit more.

Part of the material in this book can also be used as a basis for an overallcourse for graduate students who are intending to start their work in indus-trial R&D, equipment development, process engineering, plant design, andmanaging functions in industrial corporations. It also can be used for work-shops of continuing education for these working professionals.

Obviously, one could have filled the book with examples from actualprojects, but it is debatable whether more such particular examples wouldhave helped illustrate the points or distract attention from the complexissues. Furthermore, most of the examples are covered by commercial secrecyand cannot be published. So, the compromise chosen here by the author maynot satisfy every reader.

The author will be pleased to receive any comment or suggestion thatcan help expand the usefulness of this book.



The author

Dr. Joseph Mizrahi

was born in 1933 and lives in Israel since 1951 at 27AEinstein Street, Haifa, 36014, phone (972-4) 824-4431, office phone (972-4)826-0737, fax (972-4) 826-0797, email [email protected]. He holdsB.Sc. and M.Sc. degrees in Chemical Engineering and a D.Sc. in MineralEngineering from the Technion, Israel Institute of Technology in Haifa. Inaddition, he received the Diploma of Imperial College, London, 1965, andthe professor-equivalent grade of Research Institutes Scientists. He alsotaught and was a postgraduate supervisor part-time at Technion from 1956to 1979.

Dr. Mizrahi has published 14 papers for international scientific confer-ences, 29 papers in international journals, has received 20 patents, and 24communications to various professional conferences.

He worked at the IMI Institute for Research and Development in Haifafrom 1958 to 1974, first as a research engineer, then as head of the ChemicalEngineering Department. His work included basic engineering design forprocess implementation, engineering aspects of licensing agreements, anal-ysis of new processes, economic evaluations, surveys, worldwide liaisonwith engineering companies, piloting of new processes, run-in of new plantsin foreign countries, and development and testing of new industrial contact-ing equipment. In addition, fundamental research was done under his super-vision and published in the fields of mixing and separation of liquids andof hydrochloric acid technology.

From 1974 to 1978, Dr. Mizrahi was Managing Director of Miles-IsraelLtd. in Haifa, a subsidiary of a multinational corporation in food, pharma-ceutical, and speciality chemicals. This work included the completion of newplants, the introduction of new products to the world markets, and thestabilization and diversification of operations.

From 1979 to 2001, he provided independent professional consultingservices to corporations worldwide in the fields of organization and stream-lining of R&D programs; consolidation, evaluation, and transfer of know-how; initiation, organization, and evaluation of projects; process design ofnew plants; troubleshooting and expansion of existing plants; and analysisof corporate development strategy.

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Acknowledgments

This book is dedicated to my wife, Sara, for a lifetime of motivation andsupport.

I would like also to acknowledge:

• The influence of Professor Avram Baniel from whom I learned verymuch in various forms of collaboration in many projects over morethan 4 decades, since he founded and managed the pioneer teamat the IMI Institute for R&D where I spent the first 16 years of myprofessional career.

• The friendly and helpful reviews of the draft of this book by Ari Eyal,David Gonen, Chanoch Gorin, David Meir, and Tuvia Zisner.

• The long and productive interaction over all my professional life witha large number of my friends and colleagues in many countries, thenames of whom I cannot list in this limited space.



Contents

Chapter 1 Why a new industrial chemical process could be needed?

1.1 Changing world1.2 A better quality product1.3 Lower cost of production1.4 Different raw material 1.5 Ecological pressure1.6 New products for the corporation1.7 Newly available industrial technology1.8 New functions for new products1.9 Corporate public image1.10 Worth another thoughtReferences

Chapter 2 Starting the development of a new process

2.1 Driving forces2.1.1 Backing of a large corporation2.1.2 Promoting group 2.1.3 The second part2.1.4 Public authorities

2.2 How a new process is born2.2.l Normal research and development activity2.2.2 Personal motivation2.2.3 Corporate function2.2.4 Financial and commercial rewards2.2.5 False starts

2.3 Explicit definition of the development project2.3.1 Objectives and purposes 2.3.2 Patents 2.3.3 Possible industrial framework 2.3.4 Timetable

2.4 Different stages of a typical program 2.5 Corporate management procedures for new projects2.6 Worth another thought



Chapter 3 Essential resources needed for the development project: preceding implementation

3.1 Introduction3.2 Specific managerial skills 3.3 Core project team3.4 R&D laboratories and pilot installations

3.4.1 Company’s own laboratory and pilot installations3.4.2 Outside laboratories and pilot installations3.4.3 Analytical laboratories

3.5 Experts on marketing and on potential users 3.5.1 Particular terminology3.5.2 Clients’ needs3.5.3 Competition

3.6 Support from experts on hardware3.6.1. Plant engineering and operation3.6.2 Equipment design 3.6.3 Corrosion in construction materials3.6.4 Operation and process control

3.7 Support from experts in software3.7.1 Publication search and analysis3.7.2 Intellectual property and secrecy 3.7.3 Patent application3.7.4 Process modeling

3.8 Safety, public regulations, and waste disposal support3.8.1 Safety3.8.2. Public regulations3.8.3 Waste disposal

3.9 Support of specific codes relevant to plant design and operation, and product quality

3.10 Economics3.11 Development expense budget3.12 Worth another thoughtReferences

Chapter 4 Actual case examples

4.1 Nature and man: the Dead Sea4.2 Magnesium chloride-based industries4.3 Economic uses for the HCl by-product solutions

4.3.1 Strategic policy4.3.2 Coupling of HCl-producing and consuming plants 4.3.3 Timing of implementation4.3.4 Production of pure phosphoric acid4.3.5 Technological difficulties

4.3.5.1 Materials of construction4.3.5.2 Safe, stable conditions for solvent extraction

in large mineral plants



4.3.5.3 Clean starting solution for solvent extraction

4.3.5.4 Recovery of the residual solvent from different exit streams

4.3.5.5 Large-capacity liquid–liquid contacting equipment

4.4 Phosphoric acid diversification processes4.4.1 Different quality specifications 4.4.2 Solvent extraction opening4.4.3 IMI “cleaning” process4.4.4. “Close-cycle” purification process4.4.5 Mixed process4.4.6 New proposals

4.5 Citric acid by fermentation and solvent extraction4.5.1 Conventional lime sulfuric acid process for citric acid4.5.2 IMI-Miles solvent extraction process for citric acid 4.5.3 Newer solvent extraction process for citric acid

4.6 Preparation of paper filler by ultra-fine wet grinding of white carbonate

4.7 Worth another thoughtReferences

Chapter 5 Process definition and feasibility tests

5.1 Translation of the idea into a process definition5.1.1 Scope of the preliminary process definition5.1.2 Comprehensive literature survey 5.1.3 Block diagram5.1.4 Quantitative definitions of the different sections 5.1.5 Process calculations for the preliminary

process definition5.1.6 Presentation of one feasible

implementation formula5.1.7 Possible industrial implementation framework5.1.8 Timetable5.1.9 Important note

5.2 Critical and systematic review of the process definition5.2.1 Review forum5.2.2 Fundamental process issues5.2.3 Patent situation5.2.4 Profit potential

5.3 Design and execution of the feasibility tests5.3.1 Purposes of the feasibility tests 5.3.2 Equilibrium conditions5.3.3 Scale up of reactors5.3.4 Physical separation operations5.3.5 Scale-dependant and dynamic flow operations5.3.6 Extreme conditions



5.3.7 Actual raw materials5.3.8 Analytical difficulties

5.4 Analysis of the results from feasibility tests5.5 Second review of the process definition5.6 Worth another thoughtReferences

Chapter 6 Experimental program

6.1 Basis6.1.1 Experimental program purposes6.1.2 Different sections6.1.3 Quantitative data needed for process design6.1.4 Format6.1.5 Representative raw materials6.1.6 Classification of missing data

6.2 Chemical equilibrium data6.2.1 Vapor–liquid equilibrium system6.2.2 Gas–liquid equilibrium system6.2.3 Liquid–liquid equilibrium system6.2.4 Solid–liquid equilibrium system6.2.5 Reversible and nonreversible equilibrium6.2.6 Chemical equilibrium laboratory tests6.2.7 Experimental difficulties in chemical

equilibrium tests6.3 Dynamic flow conditions

6.3.1 Design data required6.3.2 Simpler processes6.3.3 Theoretical models6.3.4 Special test rigs 6.3.5 Indirect methods

6.4 Scale-dependent operations6.4.1 Vertical driving force depending

on the hydrostatic height6.4.2 Wall effect6.4.3 Crystallizer6.4.4 High-temperature equipment 6.4.5 Failure to recognize the wall effect

6.5 Reporting results from the experimental program6.5.1 Frequent partial reports6.5.2 Complete reports on the experiment part6.5.3 Implications of the results

6.6 Worth another thoughtReferences

Chapter 7 Preliminary process design for a particular proposal

7.1 Process team



7.2 Process flow-sheets7.3 Preparation of an overall detailed description7.4 Listing of all the main process streams7.5 Material and heat balances7.6 Material handling operations7.7 Summary tables for all required services7.8 Major pieces of process equipment7.9 Main operational and control procedures7.10 Listing of required staff7.11 Worth another thought

Chapter 8 Economic analysis of the specific proposal

8.1 Purpose8.2 Preliminary estimate of the Fixed Capital

investment (revision 0)8.3 Estimate of operating costs8.4 Expected net sales income estimate 8.5 Profitability calculation8.6 Optimistic evaluation of the profit potential

in other applications8.7 Possible synergetic effects with other production facilities8.8 Comprehensive report for the justification

of the specific proposal8.9 Contractual agreements8.10 Worth another thoughtReferences

Chapter 9 Working program toward a first implementation

9.1 Patent protection9.1.1 Revised or additional applications9.1.2 Extended geographical coverage of the patents

9.2 Detailed process design9.2.1 Piping and Instrumentation Diagrams

9.2.1.1 Piping lists9.2.1.2 Valves9.2.1.3 Instruments9.2.1.4 Control loops9.2.1.5 Flanged manholes and hand-holes

in closed pieces of equipment9.2.1.6 Provisions for possible future connections9.2.1.7 Non-conventional drives

9.2.2 Examples of portions of piping and instrumentation drawings

9.3 “Major” equipment packages9.4 Pilot testing of specific process operations

9.4.1 Multiple-effects evaporator



9.4.2 Liquid–liquid contacting battery9.4.3 Main problems for piloting

9.5 Modeling9.6 Complementary bench-scale testing program

9.6.1 Detailed specification of the industrial equipment 9.6.2 Pilot installations9.6.3 Process modeling9.6.4 The design of instrumentation9.6.5 Corrosion tests 9.6.6 Clarification of waste disposal issues9.6.7 Clarifying process safety issues

9.7 Preparation of product samples for market field tests9.8 Clarification concerning any formal permits needed9.9 Worth another thoughtReferences

Chapter 10 First implementation plant design: compromises and optimization

10.1 “First implementation” policy10.1.1 Expected start-up problems10.1.2 Design policy10.1.3 Identifying probable causes of problems 10.1.4 “Guarantees” for reasonable plant performance

10.2 Modeling and optimization10.2.1 Composition of raw materials10.2.2 Effects of impurities10.2.3 Changes in the kinetics of mass transfer10.2.4 Changes in specifications for the final product10.2.5 Normal fluctuations around the designed average 10.2.6 Differences in the performance of equipment

10.3 Critical pilot testing10.4 The process package10.5 The role of the engineering company in the first

implementation of a novel process10.5.1 The interests and limitations

of the engineering company10.5.2 The engineering company and the project manager 10.5.3 Specialization10.5.4 The chemical process engineering department10.5.5 Timetable

10.6 Detailed engineering documents10.7 Final review and approval for construction10.8 Worth another thoughtReferences



Chapter 11 Running in and adjustments in the new plant

11.1 The plant construction period11.2 Assembling and training the operating team

11.2.1 Recruitment11.2.2 Maintenance11.2.3 Training 11.2.4 Safety11.2.5 Functional organization

11.3 Preparation for start-up11.3.1 “Dry runs”11.3.2 The plant manager11.3.3 The construction manager11.3.4 The project manager

11.4 Preparation with real materials11.5 Strategic options for the running-in of the new plant

11.5.1 Possible causes of problems11.5.2 Unsatisfactory results11.5.3 Start-up strategies

11.6 Stabilization of production11.7 Demonstration run and project success report11.8 Optimization of operating conditions11.9 Worth another thought

Chapter 12 Consolidation of the new know-how

12.1 Updating the process know-how12.2 Final revision of the Process Package 12.3 Updating the Operational Manual12.4 Feedback from users in the market12.5 Additional patent applications12.6 New publications

12.6.1 Information on the competition12.6.2 Publications on the new process and plant

12.7 How can this accumulated specific know-how be used again?

12.8 A final note: what have we learned?12.9 Worth another thought

Appendix 1 Typical organization and contents of a Process Package

A1.1 GeneralA1.2 Definition of “black box” objectivesA1.3 Division of the process into sections as illustrated

in a block diagramA1.4 Separate discussions for each sectionA1.5 Material and heat balances



A1.6 Equipment choicesA1.7 ServicesA1.8 Materials of construction: options and preferencesA1.9 Safety aspects

Appendix 2 Functional organization structure of a typical development project

A2.1 Successive stagesA2.2 The invention and promotion stageA2.3 The process development stageA2.4 The construction and running-in period



chapter 1

Why a new industrial chemical process could be needed?

1.1 Changing world

The development of a new chemical process is a major technical, eco-nomical effort that can be justified only if it fills a definite need of anindustrial corporation. The present chapter discusses the various situa-tions in which such a need could be defined. This review allows oneconnected to the chemical industry to evaluate the probabilities thathis/her corporation would need a new chemical process in the foresee-able future. There are basic reference books that can be used as sourcesfor this initial information.

1–5

The chemical industry has always been operated in a

changing world

withexpanding markets, a need for better products at lower prices, change inraw materials, addition and removal of political barriers, great jumps in thetechnology available for industrial application, higher ecology demands, etc.As time goes on, the dynamic rate of such changes seems to be

increasingexponentially.

In the past 3 decades, in particular, it requires an open attitudefrom any corporate management towards possible process revision.

In such a changing world, an operating chemical corporation couldrequire a novel process for a certain product, if and when one (or more) ofthe

objective

situations discussed below becomes dominant and is recognized,at least inside the organization. Let us consider first the situation in whicha corporation is already producing and selling the product, but now needs

process changes

for

:

• Obtaining a better quality product• Reaching a lower cost of production• Using different raw materials• Responding to ecological pressures

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A different situation occurs when a corporation is considering makinga new product.

The company will need a new industrial process for:

• Producing according to a soon-to-expire patent• “Bypassing” an existing patent• Using a newly available industrial technology• Creating new markets with a product fulfilling new functions• Expanding its public image

1.2 A better quality product

The need for a better quality product could be felt in one of the corporation’sexisting markets and reported by the marketing organization. Such a needcould arise from the persistent requests or complains of clients or from thepressures of competitors’ products, and it could be reflected in the presen-tation of more stringent standard purchasing specifications. Furthermore, anupgraded product could open the way to other market segments.

This situation is quite common in the process industry, as a chain resultfrom changes in the downstream uses of the products. It generally motivatesa continuous effort in limited research and development (R&D) projects,resulting in

gradual changes

in the existing production technology, in anattempt to improve the product’s quality as requested. Such an aim couldpossibly be obtained, for example, by the addition of

purifying operations

tothe production line, such as distillation, recrystallization, active-carbondecolorization, ion-exchange purification, and the like, or by

compromisingon the product’s yield

in order to remove more impurities in the wastestreams.However, in many cases, a point is reached when further improvement

would no longer be possible with the existing process or with the rawmaterials presently used, or when such quality improvement would becometoo expensive. At this point, the need for a significant process change willbe recognized and defined inside the corporation, and such need could alsobe made public in the market segment. This significant process change wouldpreferably be limited to the

core production process

, while almost all of theexpensive infrastructure could most likely be maintained with minimumadjustments.

1.3 Lower cost of production

Lower cost of production is, of course, always desirable in any existing plant,either to increase the profits or to allow lower and more competitive prices.In practice, in all operating plants, this objective is dealt with continuouslyby small and gradual ad-hoc steps, which do not impair the regular flow ofproduction.

There is not always a direct link between the production cost and thesale price, and there are even examples of plants that have been supplyingan essential strategic corporate need while losing money. However, many



operating plants are living under the shadow of the possible developmentof a

more efficient, completely new

process with

drastically lower production costs

.This process may become available to the competition and may endangerthe basic economic existence of the plant. Thus, corporations must alwaysdevote a continuous effort to keeping up to date with all the developmentsthat could lead in this direction. These include higher yields, lower energyconsumption, shorter route, revaluation of byproducts, etc. This could evolveinto a

full-scale process development effort

, whenever a company intends tobuild a new plant to replace an old installation or when stronger protectionis required against the perceived competition.

1.4 Different raw material

In some cases,

different

raw materials may become available that could havedefinite technical or cost advantages. In other cases, a significant changecould be expected in the future

quality

or in the

cost

of the raw materials thatare presently used, or even in the continuation of their future supply.

The changing situation concerning the raw materials’ supply has alwayscharacterized those industrial chemical processes that start with

natural

rawmaterials, i.e., mineral ores, agricultural crops, or petroleum fractions for thepetrochemical industries. The situation could be even more sensitive whenthe raw materials from a plant are

byproducts

or

waste products

from the mainproduction of another plant that is using such natural raw materials (i.e.,grain hulls, molasses, mineral concentrate fractions, hydrocarbon streams,etc.). A similar situation relates to the use of some waste products from thecombustion in large power plants (fly ash from coal, soot, solutions fromecological scrubbers, etc.) as the starting raw materials.

For example, the world’s main supply of zirconium oxide (and zirconiumcompounds) for many decades came from a byproduct (Baddelayite concen-trate) mined in South Africa. It has been known from the 1990s that this uniquesource was progressively and irrevocably being depleted

6

and all the suppliersand users of zirconium oxide had to urgently look for new processes. Theacute need directed the users’ attention to options for extracting zirconiumoxide from the mineral Zircon (zirconium silicate), which is plentiful world-wide as a heavy-sand concentrate. Unfortunately for the developers, however,it also has a very stable mineralogical structure. To overcome this inherentstability, some proposed the use of brute force, such as fusion in an electricarc furnace at 2700˚C, followed by volatilization of silica fumes and otherimpurities (some of it radioactive) that had to be collected, or thermal disso-ciation by a shock treatment at very high temperatures in a plasma torch,followed by a wet treatment. Other proposals were based on sophisticatedchemical detours by additive reactions with calcium or sodium oxide at rela-tively lower temperatures.

7–10

The recently patented process, developed byChanoch Gorin and Joseph Mizrahi

9

for that purpose, presents an efficientnovel route and will be discussed in Chapter 5 as an illustration of severaldevelopment steps. The possibility of getting some Baddelayite supply from



a mine in Russia’s arctic Kola region, along with the rather small world market(in tons and in sales volume) also represent limiting factors in the developmentof these new processes.

In an opposite situation, the exclusive and efficient production of high-grade synthetic potassium nitrate, according to the 1967 IMI solvent extrac-tion process,

11

has been a profitable operation for several decades as theprincipal worldwide supplier, despite the well-known existence of largenatural deposits of nitrates in South America. Since the mining and refiningoperations have finally been established in Chile, the situation in this marketchanged throughout the world. Different grades of potassium nitrate arenow available to different users at different costs and the consumption ofthe highest quality synthetic product has decreased. All of these changescalled for drastic process reconsideration in the plants using the syntheticroute. Such options for change had been available for at least 10 years,

12–13

but there was no pressing incentive for a development effort.In the last few decades of the twentieth century, the fluctuations in the

quality as well as the cost or the availability of many raw materials haveoften reflected the changes in international trade, as many

political and cus-toms barriers

were added or removed. Examples of such changes are thedecolonization of many countries, the European Union and other regionalunions, the decentralization of the former Eastern block into separate coun-tries and the accelerated privatization of their industries, as well as theincreasing role of The Republic of China in all economic areas. All of thesegeopolitical changes have seriously affected the way in which many olderchemical plants have been operated for generations, and have forced com-panies to reconsider their production processes and possibly how to developalternative processes more related to the new situation.

For example, raw (brown) cane sugar could be produced somewhere inAsia, transported to a European city to be refined and recrystallized, andthen reexported around the world. Such activity could only have been devel-oped in the past generations under the cover of heavy custom tariffs, whichhave finally affected the European consumers. But the gradual reduction ofthis practice in the future also will affect a series of downstream industries,which are linked to the byproducts of the sugar refinery in Europe (i.e.,molasses or low-grade sweeteners). There are many similar examples inother fields and in other parts of the world.

In addition, the new “global village” economy has led to many internationalcorporate mergers and other “arrangements” that have affected the distributionof raw materials in different areas. This presently accepted practice constitutesa drastic change from the anticartel laws that were taken very seriously untilrecently in the American sphere of operation (at least in open references).

1.5 Ecological pressure

Such pressures have been systematically applied in the last generation by

public

organizations and/or by

statutory

regulations in developed countries, to reduce



as much as possible the environmental damages caused by some existing chem-ical plants. In many cases, serious cleanup operations have been successful andall concerned, including the employees of these plants, were much relieved.

In other situations, the response of the chemical industry to such pres-sures has been to “do something” that is not too expensive (mostly down-stream effluent treatments), and to claim to have done “everything possible,”except for the ultimate closing of the plant, which is generally not desiredby the community. In this continuing struggle, both sides are progressivelyimproving their knowledge as more experts are called in. An underlyingmenace, however, is the occasional threat to move an industrial activity toanother part of the world where ecological pressures are less demanding.

In many situations, a mutually acceptable solution would evolve froma

change in the source or quality of the raw materials

. This would require asignificant change in the main process, while retaining the plant’s entireexpensive infrastructure. In such a case, the development of the new processhas to be done within strict boundaries, but the know-how developed couldeventually be applied in future plants.

Another aspect of the ecological pressure relates to the combustion gasesfrom fuel burning, either in cars or power stations. The effluent gases from carshave been dealt with more efficiently, in particular by auto industry improve-ments and through the supply of cleaner fuels from the petroleum refiningindustry. This necessitated the development of many new chemical processes(most of them still not published). This solution is not feasible for powerstations, which are using mostly coal and the residual “dirty” petroleum heavyfractions. There an additional treatment must be done on the effluent gases onthe way to the chimney to separate the SO

2

/SO

3

, NO/NO

2

, particulate matters,and possible poisonous metallic traces. Such treatment is complicated (fromthe chemical and technology points of view) and expensive, because gases needto be cooled and then saturated with water vapors. The resulting heavy white“plume” from the chimney would be much more visible and of concern to thesurrounding population. This could also be corrected with the use of moreheating and pressure, which would result in more energy and higher costs. Ifthe chemical industry participated in such efforts, they could recover part ofthe costs from the marketing of, for instance, valuable ammonium sulfate andnitrate of fertilizer grade produced from the treatment of effluent gas. Manyprocesses were proposed along these lines and are actively being considered,however, actively but slowly by the power station operators. (No referencesare given here, considering the actual commercial interests.)

1.6 New products for the corporation

Let us consider now the situation in which the corporation has not beenproducing and selling the product, or a new corporation that is organizedfor such project.

A corporation may have been prevented from entering into a specificproduction line that was well protected by a competitor’s existing patent. Such



patents could cover either the nature (analysis, specification) of the productor a specific production process for such product. These are different issues.

If the existing patent covers the

nature

of the product

, a

process develop-ment effort

would be required as soon as it is established that such

patentwould expire

in

a few years, or if a way to

by-pass

such protection can beproposed (e.g., by a small change in the formula that does not affect theperformance). Note that the patent law prevents only the selling of theproduct covered by the patent, not the study or the preparation for itseventual production or even its production for storage. This situation hasbeen typical, in particular, to the pharmaceutical industry, as so-called

generic

medicines are sold in the marketplace at reduced prices as soon asthe basic patent covering the

trademark medication

has

expired. This sametactic relates to the fine chemicals industry, producing patented chemicalspecialties, additives, resins, catalysts, etc.

A patent covering a

specific production process

can generally be

extendedon and on, by additional filing of complementary patent applications basedon the specific practical know-how that has been accumulated during theplant’s operation. This technique is not always effective, but it is widelyused, mostly as a deterrent toward weaker, would-be competition. On theother hand, if such a competitor has a strong incentive and a good R&Dteam, a serious effort could possibly indicate some ways to avoid the formaldefinitions in the claims of these complementary patent applications. Thiswould collapse the whole patent protection. (See the case of citric acidproduction discussed in Chapter 4, Section 4.5.)

1.7 Newly available industrial technology

Generally, whenever a

new industrial technology

has become available froman

external source supplying other industries

,

typical opportunities

for new pro-cess developments should be investigated. Such new technology could beapplied to the potentially profitable production of desired products, whichpreviously could not be produced economically.

The timely recognition andexploitation of such opportunity is one of the main challenges of industrial R&D.

As a classical example, the

solvent extraction technology

has beenresearched, applied, and refined

as an industrial separation/purification toolin the 1940s and 1950s. This was due to the

urgency nuclear applications

at thetime; however, on a relatively small scale. When the essential basis of thistechnology became publicly available in the 1950s, it was recognized as apowerful separation tool by many of the best R&D leaders in the chemicalscientific profession. Its potential uses were intensively and competitivelystudied by many faculties and institutes and discussed in successive inter-national conferences. The various proposals for processes and contactingequipment then were developed further and patented in an all-out race bythose in the fields of chemical processing, pharmaceuticals, petrochemicals,fertilizers, and hydrometallurgy, resulting in dozens of highly profitableindustrial processes and enterprises by the late 1970s.



The so-called “energy crisis” of 1973 prompted many fundamental studieson the more

efficient production and use of energy

, and particularly in the chemicalindustry. Many old-fashioned processes and equipment were then condemnedas utterly inefficient and, after intensive scientific and technological develop-ment, were replaced eventually by new solutions. Many new equipment mod-els and designs were developed and introduced in the following 15 to 20 years,and most of these are now considered “standard practice.”

A similar international effort at the time was devoted to the

desalination

of seawater in order to supply potable water to arid areas at a reasonablecost. Such an intensive effort resulted in improved industrial equipment andtechnologies, which are now available on a wide and diverse scale, althoughthe industrial investments (dependent mostly on public funds) apparentlyare still not catching up with the demand. These technologies include, forexample, multistage flash evaporation, multiple-effect distillation with dif-ferent heater combinations, vapor recompression, reverse osmosis mem-branes, etc. (See the excellent review of Rafi Semiat in Reference 14.)

However, it is important to remember that these technological develop-ments should not be classified for a limited “specialized” application. Theycould also be the

critical key

for many

new processes in the chemical and bio-technology industry

that has involved a significant evaporation load, or thatoperates sections at widely different temperatures and requires large heat-ing/cooling exchanges.

Later on, the use of

advanced membranes as separation tools,

of

nano-struc-tured catalysts,

of

extraction at “supercritical conditions,”

of

the high vacuumtechnology,

of

lasers and plasma as focused heat sources,

of

micro-systems,

(toname a few), have added many new, potent processing possibilities.

Today, the advances in industrial

biotechnology

are notable and alreadyoffering industrial ways to replace many old chemical synthesis processesand to produce economically some of the large-scale organic chemicals. Thisis a direct link to the ongoing progress made by the corn sweetener industry(mostly in North America) in the industrial uses of enzymes (in particular,the immobilized enzymes) for producing very pure, defined compoundsfrom starch or cellulose by chemical and physical processes. (See some basicreferences in 15, 16, and 17.)

Many very important applications in the pharmaceutical industries forvery expensive products were handled as a “

lot of small-scale batch productionunits

.” The simpler large-tonnage fermentation processes were for a longtime limited to the smaller molecules (ethanol, acetic acid, etc.) and in directcompetition with the petrochemical processing industry, except for foodapplications. The large-scale production of citric acid by fermentationopened the way to more complex products. At present, the biotechnologyR&D handled by the largest corporations aims mainly to large tonnage,relatively lower cost, and intermediate chemicals for the polymerization ofindustrial plastic materials, such as lactic acid as just one example.

18

Of course, any such research project starts with the fermentation biologyin order to select the organism and the conditions in which the desired



compound can be reliably produced. However, one should note that

any suchfermentation

can only be operated in

relatively dilute conditions

compatiblewith the life (osmotic pressure?) of the microorganism. Thus, the desiredcompound can only be obtained in a concentration range of 1 to 8% (veryrarely up to 12 to 15%) in the fermentation broth, together with unavoidableresidual contamination from the fermentation media. A quite

expensive con-centration installation will be needed downstream, together with specific separationand purification processes, to obtain the final 100% product

.

And this fact-of-lifebrings us back to the solvent extraction and/or desalination technologiesmentioned above.

Finally, the electronic computer process control technologies, whichbecame widely spread in the past few decades, did allow the practical recon-sideration of some processes that were studied theoretically, but were previ-ously rated as difficult or even hazardous to control manually (i.e., based onthe operator’s decisions and responses). These are mainly in the petrochemicalfield, but also in the classified chemical industry for military applications.

1.8 New functions for new products

A new product could also be needed in the market to fill a

new function

atthe users’ end, resulting from some parallel technological development inother industries. Whenever the need for such a product can be defined, aprocess development and evaluation effort will be justified. Of course, thesilicon chip industry jumps to mind, but there are many more prosaic large-scale products.

For example, the production of citric acid by fermentation was handledfor many decades as a

pharmaceutical product

on a small scale. However, theexpanding industry for soft drinks and packaged food required more andmore citric acid, until it was treated as a

commodity

and produced in largertonnage in continuous plants by a completely different technology.

In a different field, the way in which fertilizers are used in more sophis-ticated and intensive farming by many developed countries, under ecologicalcontrol, has continuously changed. This has called for the supply of more

concentrated, cleaner, multicomponents mixtures

, mostly water-soluble, with lessresidual contamination of the soil and underground water layers. The sameprinciple applies to products in the insecticide and fungicide fields, as thetoxic metals were removed from the formulae and replaced by very specific,biodegradable, organic components.

The purchase specifications of many of the fine chemical intermediatesused in the mass production of plastic, refractory, and ceramic materials havealso changed significantly to meet the users’ demands. The term “advancedmaterial” is more and more fashionable these days (although not alwaysjustified) and are interesting and profitable markets that the chemical indus-try is expected to supply. This would require a significant innovative effort.

For example, a young entrepreneur named Steff Vertheimer startednearly 40 years ago to study the preparation of small bits of very hard and



tough solid material, by sintering tungsten carbide powder with variouschemical additives, mechanical pressing, and heat treatments. These prod-ucts improved continuously and now the cutting tools produced by hiscompanies throughout the world have a sizable portion of a billion dollarmarket. Unfortunately, due to the climate of terrorism there also are increas-ing markets developing today for shock-resistant ceramic protectors andbulletproof glass panels.

However, there should be a real need or demand for such new productsfrom the potential users, and not just the desire from the suppliers to sell moreor to respond to a passing fashion. When this author was starting in R&D, hewas given a project (with his tutor, A. Mitzmager) to develop applications forthe use of tetra-bromoethane (TBE), a heavy, stable organic liquid containing88% bromine with a specific gravity of about 3. The wishful purpose of thisdevelopment was to increase the limited markets that existed for the companywhich was (and still is) making and selling bromine compounds. TBE wasused then only in mineralogical laboratories for bench-scale, “sink-float” sep-arations between solid particles of different densities after the controlled dilu-tion of TBE with a solvent. For example, a mixture of particles is slurryed ina liquid of specific gravity 2.83. All the “reject” particles with a lower averagedensity will float while the heavier particles with valuable metallic contentwill sink. So, why can’t similar separations be obtained on an industrial scale?

This R&D project was a very interesting challenge and within a coupleof years several possible industrial applications became focused. A contin-uous separation technology with liquid cyclones was developed and piloted,and methods for the recovery and recycle of the TBE were designed andtested. The economics looked good on paper and the know-how (with fulltechnical assistance) was offered practically free of charge to any user willingto buy the TBE.

19–26

However, despite all the sales efforts, nothing really happened in theindustry. A basic difference had been ignored; that separating a

hydrometal-lurgical

plant (which is basically a chemical plant, using acids or cyanide orsimilar materials) from a

mineral beneficiation

plant, where, at most, smallquantities of chemical

reagents

could be handled. This difference is not rea-sonably

objective

, but it relates to the

people

, organization, management, andstaffing. Apparently, no manager of a mineral plant was willing to have aseparation unit with thousands of tons of a bromine compound in his back-yard, and all the potential objective advantages and profits could not changethat fact. This manager may be convinced that nothing would go wrong aslong as the plant would be operated according to the instructions. But healso knew his staff and that, somehow, someone could make a mistake, andhe had enough worries to keep him awake at night.

This lesson was painful but clear; the developing team should try to putthemselves in the place and the mentality of the potential user of the newproduct. They should ascertain that they

would

like to have such a newsupply or means as this before convincing themselves that there

should be

aneed and a market.



1.9 Corporate public image

The development of a novel

high-tech

chemical process technology has oftenbeen used to enhance the

public image

of a chemical corporation as a

progres-sive

factor, particularly by those companies operating old plants in crowdedareas. Of course, this cannot be the main reason for a new developmentproject, but it could be a contributing factor. Although it is quite difficult inthese cases to separate publicity from fact, this factor has often been usedeffectively by interested parties to gain the good will of upper managementso they will invest in a novel process development, in particular, in this high-tech generation.

Another related aspect, which is recognized inside the profession buthardly ever discussed publicly, is the importance of the

professional self-esteem

of the engineering and R&D staff of the corporation. Their involve-ment in a pioneering development should boost their interest, loyalty, and

efficiency

. Upper management does not always appreciate this effort andoften act as if employees are disposable. In many cases, temporary pres-sures and false economy considerations have led upper management todrastically reduce, or even eliminate altogether, the R&D and new projectbudgets. Such decisions could have an immediate effect on the yearly profitstatement, but it generally leads to a serious loss in the corporate marketposition in the future, as available know-how becomes obsolete and themore qualified individuals leave the company.

1.10 Worth another thought

• The development of a new chemical process is a major technical-economical effort that can be justified only if it fills a concrete needof an industrial corporation.

• All operating plants are living under the shadow of a possibly moreefficient, completely new process with drastically lower productioncosts that may endanger the company’s basic economic existence ifit ever becomes available to the competition.

• All the geopolitical changes have seriously affected many olderchemical plants, forcing the owners to reconsider their productionprocesses and develop alternative ones.

• If an existing patent covering the nature of a “valuable product ofinterest” is due to expire, or if a way to by-pass it can be proposed,a process development effort is justified.

• Whenever a new industrial technology has become available, oppor-tunities for new chemical process developments should be envisioned.

• The biotechnology R&D handled by the largest corporations aimsmainly at large-tonnage, relatively lower cost, and intermediatechemicals for the polymerization of industrial plastic materials.



• Any industrial fermentation can only be operated in relatively diluteconditions, and a very expensive concentration installation will beneeded downstream, together with specific separation and purifica-tion processes.

• A new product could be needed to fill a new function at the users’end, resulting from parallel technological development in other in-dustries. Such a need will justify a process development and evalu-ation effort, if there is a real need from the potential users and notjust the desire from the suppliers to sell more.

• The developing team should try to put themselves in the place of thepotential users of the new product and ascertain if they would liketo have this new supply, before claiming that there should be a needand a market.

• The professional self-esteem of the engineering and R&D staff is veryimportant to a company, and their involvement in a pioneering de-velopment should boost their interest, loyalty, and efficiency.

References

1. Hawley, G.G.,

The Condensed Chemical Dictionary

, 10th ed., Van NostrandReinhold, New York, 1981.

2. McKetta, J.J. and Cunningham, W.A.,

Encyclopedia of Chemical Processes andDesign

, Marcel Dekker, New York, 1983.3. Meyers, R.A.,

Handbook of Petroleum Refining Processes

, 2nd ed., McGraw-Hill,New York, 1996.

4. Bickford, M. and Kroshwitz, J.J.,

Concise Kirk-Othmer Encyclopedia of ChemicalTechnology

, various eds., John Wiley & Sons, New York, 1999.5. Comyns, A.E.,

Encyclopedic Dictionary of Named Processes in Chemical Technol-ogy

, 2nd ed., CRC Press, Boca Raton, FL, 1999.6. Skidmore, C.,

Review of World Baddelayite Production and Future Outlook

, pre-sentation to the Zircon 1995 Conference, Munich, May 1995.

7. Poleatev, I.F., Krasnenkova, L.V., and Smurova, T.V

.,

Manufacture of zirconi-um oxide for fusion cast

, Tsvetn. Met. (Moscow),

12, 56.8, 1988.8. Tan Guoca et al., Preparation of zirconium oxide from zircon by slaked lime

sintering process,

Faming Zhuanli Shemqing Gonkai Shuomingshu

CN, 1, 063,268, August 1992.

9.

Mizrahi, J. and Gorin, Ch., Process for the manufacture of substantially purezirconium oxide from raw material containing zirconium, Israel Patent. Ap-plication 127,848, December 1998; PTC/Il 00/00125, March 2000.

10. Schoenlaub, R.A., Method for Manufacturing Zirconium Oxide and Salts, U.S.Patent 3,832,441, July 1973.

11. Araten, Y., Baniel, A., and Blumberg, A., Process for the manufacture ofPotassium Nitrate,

Proc. of the Fertilizer Society

, No. 99, 1967. Also U.S. Patent2,902,341, 1959

.

12. Eyal, A., Mizrahi, J., and Baniel, A., Potassium nitrate through solvent extrac-tion of strong acids, I&EC Proc. Dev., 387, 1985.



13. Mizrahi, J., Improved process and apparatus for the production of potassiumnitrate, Israel Patent Application 9347HA1, 1993. (Assigned to Haifa Chemi-cals, Ltd.)

14. Semiat, R., Desalination, present and future, Water Int., 1, 54–65, 2000.15. Vogel, H.C. and Todaro, C.L., Biological Engineering Handbook Principles: Process

Design and Equipment, Noyes Publishing, Park Ridge, NJ, 1996.16. Blanch, H.W. and Clark, D.S., Biochemical Engineering, Marcel Dekker, New

York, 1997.17. Johnson, A.T., Biological Process Engineering: An Analogical Approach to Fluid

Flow, Heat Transfer, and Mass Transfer Applied to Biological Systems, John Wiley& Sons, New York, 1998.

18. Baniel, A., Eyal, A., Mizrahi, J., Hazan, B., Fisher, R., Konstad, J., and Steward,B., Lactic Acid Production, Separation and/or Recovery Process, U.S. Patent5,892,109, 1997. (Assigned to Cargill, Inc.).

19. Mitzmager, A. and Mizrahi, J., Pre-concentration of flotation feed with TBE,Min. J., 7, 481, 1961.

20. Mitzmager, A. and Mizrahi, J., Improvement in the Sink-Float Classificationof Solid Granular Material, Israel Patent 18,108, 1962.

21. Mitzmager, A. and Mizrahi, J., Method for the Sink-Float Classification of WetGranular Material, Israel Patent, 18,230, 1962.

22. Baniel, A., Mitzmager, A., Mizrahi, J., and Star, S., Concentration of SilicateMinerals by tetrabromoethane, Trans. Am. Inst. Min. Eng., 146–154, 1963.

23. Boskovich-Rohrlich, E., Mitzmager, A., and Mizrahi, J., Structure and benefi-ciation of a low-grade iron ore, Min. Mag., 325–331, 1963.

24. Schachter, 0., Mitzmager, A., Mizrahi, J., and Brillianstein, A., Classificationand jigging with heavy liquids, Trans. Am. Inst. Min. Eng., 91–96, 1964.

25. Mitzmager, A. and Mizrahi, J., Correlation of the pressure drop through smallcyclones operating with dilute pulp of various liquids, Trans. Inst. Chem. Eng.(London), 42, 152–159, 1964.

26. Mizrahi, J., Separation Mechanisms in Hydro-cyclone classifiers, Brit. Chem.Eng., 10, 686–692, 1965.



chapter 2

Starting the development of a new process

2.1 Driving forces

2.1.1 Backing of a large corporation

It is evident at the onset that the

development and implementation

of a novelindustrial

chemical process is a very expensive project; that only the backing of asizable corporation can carry it to

completion in the final instance, and thenonly if and when it fits into its corporate framework. Thus, this backing isa

necessary condition

for the

completion

of the project.

2.1.2 Promoting group

However, in most cases, such development projects can be initiated by agroup of

promoters

, who could be a part of

one or more

of the followingfunctions: an individual scientist, an academic department, an industrialresearch organization, or an engineering company. Lately, certain “risk cap-ital” funds are involved in such promotions as well.

In certain cases, this promoting role could be carried out inside thecorporation by its own R&D section, by its new business department, oreven in many cases by able production engineers. (One may also mentionthat in certain large corporations, some “secret” development projects areactively encouraged by certain executive managers, who report only to themwith entirely separate budgets.).

This promoting group could be formally organized as a legal partnershipand raise a limited investment, in order to manage and carry on the

first part

of the development project, which includes the following elements:

• The “invention” (in fact, a

proposal

for a new industrial process) withits justification compared to the existing situation, its basic chemistryand mode of operation, and its implementation logic.



• A sufficient basis for the formal claims in a

patent

application, whichcan derive from a novel reasoning and/or of newly-discovered fac-tual evidence.

• A bench-scale experimental

demonstration

of the novel aspects of theproposal, which could convince, or at least impress, experiencedscientists.

• A preliminary technical, economical study of the proposal, whichindicates conclusively that its

potential

profitability should

justify thenecessary investment in the development program

.• The

promotion

, i.e., the location of potentially interested corpora-tions, contacts and presentations, and negotiations of a commer-cial contract, until the project is sold and transferred to a corporateorganization.

2.1.3 The second part

The

second part

of the project follows the transfer of the management andthe associated responsibility of the project to the corporation.

The transfer, from the promoters in the first part (or period) to corporatemanagement in the second period, changes drastically the vision and rulesof the game. This transfer could be a

delicate procedure with many pitfalls

, ascompletely different

driving forces

are operating during the development andimplementation of a novel industrial chemical process.

In the

first period

, the promoters are mainly interested in all the

principal

issues that could affect the elaboration of the rationale of theproject and the choices of possible implementation objectives. Such issuescould determine the decision-making process of each of the prospectivecorporate candidates, and result in their buying and implementing theproject. Obviously, the promoters, as a small group, have not the meansnor the time, and possibly not the ability to pursue in detail all of thepossible options.

In the

second period

, on the other hand, the corporate project manager istaking over the decision-making, with the concrete task of optimizing thenovel process in

one particular context

, and building and operating a

viableplant

. The manager has to cover every significant aspect of the developmentand implementation, but in a definitely

limited scope

.

2.1.4 Public authorities

Public authorities

also are actively pushing or helping such industrialdevelopment in many countries. For example, funds are made availableas grants, loans, or subsidies (i.e., tax credits) for industrial R&D budgetsand/or for risk capital companies, and these funds could facilitate thepromoters’ initiative or corporation incentive. However, this procedurecould also introduce significant restrictions concerning the location andownership of the plant.



2.2 How a new process is born

The

objective need

for a new process and its potential application must firstbecome identified in one of the situations listed in Chapter 1, and becomeknown to the professionals in the field. Only then will the

subjective motivation

for an industrial invention be actuated in one or more of the following routeslisted below.

2.2.l Normal research and development activity

Normal R&D activity creates a situation in which a

better basic scientificunderstanding of the limitations of the existing industrial processes

is systemati-cally associated with the study of similar developments, and with new

available data or technology in parallel fields

. When scientists are saturated withthis information, an

idea

may come to someone in the form of a proposal:“Why can’t we do it better another way?”

This “click” is part of the functions normally expected from anyindustrial R&D group, albeit in a corporation, an academic department,or an industrial research organization. Nevertheless, the mechanism ofits occurrence is not well understood, and it is generally attributed toindividual characteristics. (

Despite much interest, most of the studies anddissertations devoted to this idea-generating psychology are related to artisticcreation and apparently there is still no accepted theory as regard to scien-tific/industrial inventions

.)But not all such ideas are actually pursued. Many (one would say most?)

are impractical, premature, or incorrect in some aspect. There is no discreditin that, since a more fundamental study of the limits of the problem can onlybe reached by raising these proposals. Many potentially interesting ideascould also be stopped just for lack of follow-up by the initiator, who, forexample, could be too busy

.

One of the

main challenges

of any R&D organi-zation is to have a

proper forum and a routine procedure

for the systematicrecording and review of such ideas, which would then avoid any possible bias dueto personalities, positions, and past records

.

2.2.2 Personal motivation

The main driving force for a

successful innovation

(the invention, the promo-tion, and the first steps) is without a doubt the

personal motivation

of themore-talented R&D scientists. In addition to their

genuine scientific curiosity

and drive, a series of successful innovations is generally considered as a keyfor their personal advancement, their public recognition, and their personalsatisfaction. It could also be linked to a financial bonus or other incentivesin certain organizations.

Since these more talented scientists could also be successful andhappy in an academic position, a major challenge for

the management



of the industrial R&D organization

is to

create conditions in which theirscientists would be interested in continuing to work there, effectively and for aprolonged period

. Of course, this motivation is a delicate matter, whichcould concern nonscientist personalities as well. There are no easy short-cuts.

2.2.3 Corporate function

The managers of the dedicated corporate departments (R&D or “new busi-ness”) have the role, the staff, and the budget to generate new projects, andthey are generally looking for

new ideas that may be worth promoting. Thesenew subjects could be found internally by a continuous and systematiccovering of their defined territory, or from the outside by promoters whoare familiar with their corporate business field.

On the other hand, once their hands and means are more or less full (asdecided in advance by the yearly plans and budget), they have to find waysto delay additional new proposals without causing too much ill will withthe promoters who are offering a golden opportunity. More flexibility in thismatter could give better overall results.

2.2.4 Financial and commercial rewards

Each participant in the promoter/developer group (external to the corpora-tion) is normally motivated by some

financial reward

, expected from a suc-cessful implementation, including buy-in at an early stage, development,and re-sale when ready.

But some of the participants in this group also could have additionalcommercial considerations related to their other activities, such as thesupply of engineering services, the sale of proprietary equipment, theassignment of marketing rights, exclusivity in certain services, agent’scommission, and so forth. Unless all of these interests are clear from thebeginning, they could lead to conflicts between the partners. Such unpleas-ant cases are not uncommon; therefore, it is advisable to have a clear pictureof the situation at the onset of a joint venture to help promote an innovativeprocess development.

2.2.5 False starts

It is generally recognized that, due to the pressures stated above, a

verylarge part

of these “would-be inventions” eventually will be false startsand dropped sooner or later. This situation could also happen to excep-tional R&D scientists who, following reappraisal, will readily pull backtheir proposals (for the time being) and find other avenues for theirefforts. There is no shame in such a decision, as this is an integral partof R&D work.



Unfortunately, some of these false starts may take a long time to die,wasting precious time. The general efficiency of an industrial R&D organi-zation depends on the

routine screening procedure for new ideas

, preferably bya peer review

that is more readily accepted than a manager’s ruling.

2.3 Explicit definition of the development project

It is essential, at the beginning of every development project, to detail explic-itly what the

project will try to achieve and what would be considered a successfulimplementation

.This clearly written definition may be critical for the success of the entire

project, and the promoting group should give it utmost attention. The firstbenefit will be that thorough discussions will force the group to focus itsproposals exactly toward objectives and procedures that are feasible in thisreal world. This definition should include the following components listedbelow.

2.3.1 Objectives and purposes

A

quantitative

definition of the actual objectives and purposes of the devel-opment project, as compared with the known existing situation, may include,for instance:

• Minimum specification of the new product or products• Maximum acceptable production cost• Minimum recovery of the valuable component• Acceptable waste disposal, etc.

2.3.2 Patents

There is no point, however, in starting a significant development effortunless there is a reasonable prospect for an eventual patent protection incase of positive results. An adequate patent search and strategy shouldbe discussed and decided at an early stage, after consultation with therelevant experts. This analysis should start with a clear statement anddefinition concerning:

• Extent of

effective patent protection needed

for the increasingly largeinvestments in industrial research and the potential profits

• The need to avoid some constrains in an existing patent

2.3.3 Possible industrial framework

A

projection

of the eventual (or possible, probable) industrial implementation

framework

of the new process is needed to help cement the technological factors



specific to that framework. This projection, which will be continuouslyupdated with a compilation of more available details, generally includes:

• Scale of production, which affects the equipment size and function• Different options of raw materials; availability of critical services• Possible synergetic coproductions, local regulations, etc.

In some cases, the initial projection of such framework may only bewishful thinking in the eyes of the promoters, as the corporation concernedmay not have been approached in the early stages. But, at least, there shouldbe a reasonable

assumed

framework since, without it, the process develop-ment would be mere speculation.

2.3.4 Timetable

In industrial reality, once the need for a new process has been recognizedand a feasible idea or proposal has been advanced and approved, theresults of the development effort should be

delivered reasonably fast, despitethe many complex issues and decisions that need to be resolved

. An often-citedgoal, before the detailed engineering of a new plant can be started, isbetween 12 and 24 months.

A detailed time-table — desired or imperative — should be worked outand included in the particular project definition, listing all the differentprojected activities (see Section 2.4 Different stages of a typical program),the periodical review points, the change points in project management (pass-ing the torch), the requirement for introduction of additional support teams,and the emphasis on specific efforts.

Note that the change in project management will generally require a fewmonths for systematic transmitting of know-how and of periodical summaryand review of the process package.

2.4 Different stages of a typical program

The different stages of a typical development and implementation programare listed below relating to the author’s own experience. Each of thesedifferent stages will be discussed in detail in the remaining chapters of thebook. Of course, there could be many different situations relating to specificcase histories. One should emphasize that in many new processes, therequirement for a comprehensive pilot work is essential to ensure a thoroughunderstanding of the effects of the different recycle streams.

Note that this is not a simple procedure and there could be

at least fivereviews

at different levels of responsibility and authority. Each of thesereviews should be well prepared and be concluded either in a “no” (closingthe project) or a “maybe” (okay to proceed to the next step) decision . Incertain cases, additional facts and information are required before a partic-ular review can be concluded.



2.5 Corporate management procedures for new projects

In recent years, a number of management procedures have been adopted inmost large corporations for the control of strategy, choice, and cost of devel-opment programs. These procedures resulted mostly from the large number

Definition of the Objective Need for a New Process• Study of the existing process

limitations, yielding the

idea

• First review of the idea in the promoting group

Okay to proceed

Definition of the Development Project• Grouping of the core project team• Transformation of the idea into a

process-working definition• Critical and systematic review Okay to proceed

Feasibility Tests and Analysis• Literature survey• Review Okay to proceed

Promotion• Patent application• Experimental program and reporting

of the results• Preliminary process design for a

particular proposal• Economic analysis of the specific

proposalNegotiation, Agreement, and Transfer to the Corporation

• Management review Okay to proceedWorking Program Towards a First Implementation

• Complementary R&D• Piloting and modeling• Patent updating• Process and equipment detailed

design• Market tests of the products• Formal permits required•

Final review

Decision to proceed with the first plantProcess Package and Plant Design

• First plant design• Modeling and optimization• Critical piloting•

Final engineering review

Approval for constructionConstruction and Running-In

• Personnel training• Running-in and adjustments in the

new plantConsolidation of the New Process Know-How Package

• Patent updating



of

new product

developments aimed at the consumers in an affluent society,such as electronic hardware and software, travel, household products, toysfor all ages, etc. Large R&D budgets have been geared in this direction andthe different management schools have stepped in with recommendationsand procedures for “doing it better.”

Among the more known, commercially available management tools, forinstance, is the “Stage-Gate” system, propagated by Dr. R. G. Cooper fornew product development. This system combines certain strategic principlesand procedural steps for

choosing the right product

to develop from an

assumedlarge number

of proposals, and how to control the different steps of theprogram with “Gatekeepers,”

all from inside

the corporation, starting withthe “invention.”

There is no doubt that such management tools could be very useful tothe extent that they would force, step-by-step, the preparation of orderlydocuments, analyses, and reviews of all different aspects of the project. Aftersuch preparation, the case will be better based, but the value of such deci-sions will still depend on the decision-makers.

Although the approach described in this book for development of a new

chemical process

to respond to a recognized need (as discussed in Chapter 1)have different emphasis, it is also based on stages and successive reviews.Therefore, the employees and consultants of corporations that have alreadyadopted one of the above mentioned R&D management procedures, suchas Stage-Gate, will find it easier to understand and assimilate the messagein this book, and to use the

detailed recommendations

within their corporatedirectives.


• The “invention” is, in fact, a “proposal” for a new industrial processwith its justification related to an existing situation, its basic chem-istry and mode of operation, and its implementation logic.

• The transfer of decision-making from the promoters to the corporatemanagement can be a delicate procedure, as completely differentdriving forces are in power. The promoters are mainly interested inthe “principal” issues affecting the project rationale and the possibleimplementation objectives. Later, the corporate project manager hasto cover every significant aspect in a definitely limited scope, sincehe has a concrete task of optimizing the novel process in one partic-ular context: building and operating one viable plant.

• The R&D systematic activity associates a better basic scientific un-derstanding of the limitations of the existing industrial processeswith the study of similar developments and with new available dataor technology from parallel fields.



• One of the main challenges of any R&D organization is to have aproper forum and a routine procedure for the systematic recordingand reviewing of proposed ideas.

• There is no point in starting a significant process development effortunless there is a reasonable prospect for an eventual patent protection(in case of positive results.)

• Without a projection of the eventual industrial implementationframework of the new process (scale of production, options of rawmaterials, availability of critical services, local regulations, etc.), theprocess development could be merely speculative.

• The different stages of a typical development and implementationprogram would include at least five comprehensive reviews at dif-ferent levels of responsibility and authority, each ending with aNo/Maybe decision.



chapter 3

Essential resources needed for the development project: preceding implementation

3.1 Introduction

A new industrial chemical process is concerned, in the final analysis, withchemistry and technology, plants and products, and markets and finances.But the successful development and implementation of a project dependsmostly on the interaction and cooperation between

many critically importanthuman factors

. This basic statement was not realized at the onset by allconcerned. When this author suggested it in a paper in 1972

1

after a year ofstruggling with a very difficult new plant start-up and after long nightsthinking why it went wrong, the thesis apparently touched a nerve, as anoverwhelming number of colleagues from around the world responded tothe idea.

Academic research

is done mostly in small groups at universities andinstitutes. Until the final product (the thesis, the paper) is sent out, anyinteraction with other colleagues on the subject of research is done purelyon a

voluntary

basis. Apart from his/her personal scientific curiosity anddrive, the external interests of each of the researchers are also obvious, i.e.,personal advancement and recognition, or the next research grant. (At leastit was so before the epidemic of “start-up” ventures.)

Applied

R&D

toward a new industrial process is very different, as the

timely contribution

of many professional specialties is

essential

and

critical

toits success (after the first inventive steps). In many cases, this interaction isnot well understood by some professionals coming from academic researchand this has often been a major source of problems. Therefore, it is importantto discuss this “fact-of-life” in detail in this chapter, together with the essen-tial resources needed for the process development, up to the decision tobuild a new plant.



3.2 Specific managerial skills

A qualified and efficient

manager

for a

process development

project

incorpo-rates certain personal qualities and professional experience, since he/she hasto deal with a different and special management challenge. The manager ofsuch a

process development

project needs to:

•

Mediate

the essential

work

and the

temperamental egos

of individualpersonalities (inventors, promoters, experts), as well as the orderlycoordination and interaction between many different disciplines andfunctions, and of proper formalities, records, and communication.

• Report upwards and find his way through the internal politics of alarge corporation, in which every director may have his own vision.

• Have an

extensive

and

diversified background

in the

basic sciences

, in the

engineering disciplines

, in

project

control, and in

plant operations

.• Be willing to learn something new every day from every new situation.• Assume his first project management responsibility preferably after

his participation in several similar projects, as a professional engineerand as assistant project manager.

Managing a project long term is generally an exhausting experience,so a successful project manager expects after that and generally gets apromotion to a less-demanding job. The scarcity of qualified managers isgenerally recognized as a critical bottleneck in many organizations. A not-so-qualified individual also may succeed, but he/she should be ready toask for advice when needed and have adequate support from managementand external consultants.

3.3 Core project team

The core project team consists of all the members reporting directly to theproject manager and working full time (or at least most of their time) on theproject. This core team generally includes, in addition to the project man-ager’s executive assistants, people from other departments and organiza-tions who are temporarily delegated and integrated into the project team forthis particular project. For example:

• Inventors and researchers from the R&D promoting team who arecontinuing to work with the project team as long as they are needed,bringing with them their scientific knowledge of the subject and help-ing in the coordination of future R&D activities, along with the processengineers who are taking over the continuation of the process design.

• A specialist from the products’ marketing organization who is assistingin pinpointing the market needs and supervising the product’s testing.

• A number of process chemical engineers from the engineering de-partment (or division or selected company) who are in the interim



delegated to lay down the essential process flowsheets, prepare bal-ances and economic spreadsheets, equipment comparison, engineer-ing and optimization studies, budgets, etc.

This group is

expected to work as a team

so that all its members have accessto

all

the documents and are aware of

all

the facts, and each can contributehis opinion

freely

inside the team. (Communications outside the team are, ofcourse, subject to the manager’s instruction.) Therefore, it is important andit should be accepted that external credits are given to the team as a wholeand not to individual member’s contributions. All of the team’s outgoingdocuments are approved and signed by the project manager or by his func-tional representative.

3.4 R&D laboratories and pilot installations

3.4.1 Company’s own laboratory and pilot installations

In many industrial companies, the promoters and project manager have touse mostly the

company’s own laboratory and pilot installations

in order todecrease costs and preserve confidentiality. This may be helpful on one handsince these laboratories should be generally familiar with the materials,analytical methods, and modes of reporting. On the other hand, this couldalso be a limiting factor in that conflicting lines of duty and priorities areplaced before the laboratory managers with the representatives of severalprojects putting pressure on them.

3.4.2 Outside laboratories and pilot installations

In other cases, the promoters and the project manager are allowed to contractparts of the testing program to outside laboratories and pilot installations,i.e., universities, public institutions, or private specialists. As such laborato-ries are generally limited in their specialization, each would be doing onlya

specific part

of the overall job. Another fact of life is that the better labs tendto be over-booked and may not always be available when needed. Thus, thechoice,

motivation,

and efficient use of these laboratories require

experiencedcoordination

and

complex planning of all details

so that results will be receivedin time and be relevant to the specific conditions. Unfortunately, the impor-tance of this detailed coordination job is not always appreciated and is oftendelegated to the younger, less experienced engineers on the team.

3.4.3 Analytical laboratories

The

larger part

of the man-hours (and cost) of an R&D program is generallydevoted to the performance of the chemical and physical analyses. Yet, inmany cases, it has been seen that some researchers and engineers relate tothe analytical laboratories as they would to automatic machines — bring in



the samples, press a button, and collect the results. This approach is mostunfortunate and often backfires.

Any analytical test work, and in particular for R&D, involves complexdecisions and good judgment. The managing and principal chemists of theanalytical laboratories are, in most cases, highly trained professionals withextensive and varied experience and interests. It is strongly advisable to seektheir cooperation at the onset by telling them about the aims and scope ofthe project, inviting them to meetings and reviews, and discussing with themthe significance of the results. The contribution of these chemists has beenfound to be very fruitful in many cases.

The exact definition and limitations of the analytical methods oftenpresent a difficult area, since there is generally a direct link between the

accuracy of the results

and their

unit cost and time delay

. The highest level ofaccuracy is not always justified and affordable, especially in the

exploratorystages

of the R&D where a

fast procedure

is preferable.For example, the early process development and promotion of the trans-

formation of solid potassium chloride into solid potassium nitrate was basedon the direct examination under a microscope with polarized light. The blackpotassium chloride (cubic crystals) could be seen as they transformed intobrightly colored product (monoclinic crystals) when subjected to a specificsolution. Thus, many different compositions of such solutions could bescreened rapidly. This was also an impressive demonstration to visitingdignitaries to the laboratory, which helped promote the sale of the process.

It should also be noted that the accuracy and significance of the resultfrom any chemical analysis could not be any better than the sampling pro-cedure that was used to procure the sample for analysis. Sampling of mul-tiple-phases from small test vessels can often be a complicated task requiringa delicate touch.

3.5 Experts on marketing and on potential users

3.5.1 Particular terminology

A contribution of experts could start with the trivial aspect of the

particularterminology and the sets of units

used for centuries in certain market segments,for example, P

2

0

5

, Baume, Avoirdupoid, grains, ounces per metric ton. Thereare also specific analytical tests, such as the

citric soluble P205

used in fertil-izer, which is supposed to quantify the process in which phosphates areabsorbed by the plants’ roots, and also some very particular wording ofspecifications and legal references.

These

arbitrary, often nonsensible

names and units can be infuriating forscientists who are newly exposed to them, but they cannot be changed inpractice, so one should accept them and make use of a translation sheet orprogram. Before being “accepted into the family,” the project team is often

instructed

to demonstrate a

thorough familiarity

with these terms in all contactswith potential partners and clients.



3.5.2 Clients’ needs

On the more substantial level, the process development team should under-stand from these marketing experts which details and features of the prod-ucts under consideration are

really

desirable and important to their finalusers from their point of view, and

what these final

users would be

ready topay for these

results, if they were given the choice between different qualities.(Consider the classical example of instant coffee. Should one pay more forfreeze-dried than for spray-dried? It’s a matter of taste.)

In many real cases, the most desired features can be technically achiev-able, but this result can increase the final production cost too much, therefore,a compromise should be reached. So, the

practical sale price structure

of theparticular products line must be well understood at an early stage, althoughthe preferred marketing aims may not always be explicitly announced

outsidethe core team

in order not to alert the competition.

3.5.3 Competition

In other cases, existing competitors operating in this market may appearto be closer to approaching these final users’ needs. Such a disturbingsituation should be recognized and extrapolated by marketing expertsfrom their sources of information in the markets, so that the project teamcan focus on their work and possibly supply attractive improvements

intime.

3.6 Support from experts on hardware

3.6.1. Plant engineering and operation

When implementing the new process at an

existing

plant site,

cooperation

between the process developing team and the senior technical staff of theplant should be established early. This will be beneficial to both sides. Admit-tedly, such cooperation may often cause personal problems, mostly due tothe

differences in priorities, point of view,

and

style of communication

betweenthe two groups (i.e., what do they know about running

a plant and aboutR&D science?). Here, the personality of the project manager should bridgethese differences, and it is always better to address and solve them calmlyand in a timely manner than under decision-making pressure. The plant’smanagement also can

contribute some very good ideas and propose effective andpractical design solutions

from their point of view, and should be

given credit

for that

.

This cooperation can become critical anyway if it is decided to installand run a pilot plant at the plant’s site and connect it with “live” streams.

On the other hand, several cases have been known of new processes thathave been developed “in secret” in the corporate R&D facilities and thatwere later bluntly opposed and rejected by the plant’s operating manage-ment who felt that it was

forced on them

without their consultation.



Whenever possible, the process developing team should get a clear

andearly

picture of the

eventual implementation

conditions of the new process inconnection with an existing facility, including its infrastructure, existingservices, and waste disposal possibilities. These specific conditions can pose

objective limitations

that have to be taken into account in the early stage ofdevelopment, rather than making changes later. For example, the designtemperature of the cooling water supply depends on the average climaticconditions in the area and can be critical when designing an installation forevaporation/condensation under high vacuum.

3.6.2 Equipment design

In many cases, the design of a novel process section

can be criticallylinked to one

particular piece of equipment

or

specific technology.

Thus, theprocess’ results will depend not only on the process chemistry, but alsoon a particular combination of equipment design factors and operatingconditions.

Furthermore, it may be that this particular piece of equipment or specifictechnology can be supplied only by a

very small number

of specialized com-panies, each of them with their particular know-how, or at least their claimsof such know-how. For example, this situation can apply to industrial crys-tallizers, special dryers for hygroscopic solids, industrial plasma heat torch,and the like. The process developing team may be feeling “cornered” if theyare operating in a corporation committed to the “purchase-by-bid-only”procedure, since such formal link with a specialized supplier may cause thefollowing problems.

• From the beginning, in order to get enough information from anywould

-

be supplier for evaluation and preselection, a mutually bind-ing secrecy agreement should be negotiated. This is not a simpleproposition, but requires at least that the novel process has alreadypassed the patent application stage and that the equipment supplieris not already signed up with competing corporations.

• The pilot tests should be done with

one particular supplier

in mind(most probably with his pilot equipment) and the cooperation of hisstaff after a basic commercial framework has been established.

• This procedure would give the selected equipment supplier a clearadvantage in the final price negotiations, which would include someremuneration for his know-how and past experience, and for hisguarantees and assistance in start-up.

• It would be logical to include the engineering company staff at thisstage of “prepilot” equipment survey and contract negotiations, anduse their experience and services also in the pilot testing. However,this participation would need to advance the decision on the contractbid for the choice of the engineering company more than it wouldbe generally anticipated.



3.6.3 Corrosion in construction materials

In many cases, the novel chemical process conditions can introduce

unknown

corrosion aspects, which have to be clarified

as early as possible. Theseaspects relate to the reliability of the materials of construction that will beused for the equipment and for the piping. This reliability bears first on

safetyconsiderations

deriving from a possible accidental failure (particularly in pres-surized and/or high-temperature systems

),

but also on the

estimate of thelifetime, supply cost, maintenance schedule of each piece of equipment, orthe possibility of contamination of the product with metallic traces.

The orderly and reliable testing of the corrosion rate for

each combination

of one particular choice of construction material and one particular set ofprocess conditions is a relatively

long procedure

of many months, starting withobtaining reliable samples of unusual materials of construction. Furthermore,the

exact and final

conditions for such a corrosion test might be known onlyafter the process development has firmed up (compositions, additions, temper-atures, etc.). Therefore, the tendency is to be

safe

and to test the worse possibleconditions. But this choice can also lead to an

expensive overshooting

. Even if thechoice of just-in-case better/safer materials is available, it may result in a sig-nificant increase in investment costs and reduce the calculated profitability.

The presence of certain “trace elements” impurities in certain streamscan affect seriously the corrosion properties. A classical example is the pres-ence of copper cations in a solution, which can “cement” on a steel surface,create a corrosion cell, and (quite surely) a hole. When such possibility isdefined and confirmed, the need for certain pretreatments or a side-streamtreatment becomes an essential part of the process or, in certain cases, theneed for bleed streams to avoid accumulation of such impurities.

This is a highly specialized field, and it is advisable to engage, from anearly stage, the support of an expert consultant with relevant industrialexperience, who can recommend the options and procedures to arrive

in time

at the optimum specifications for materials of construction. Furthermore, thepublic authorities and the insurance company representatives often insist onreceiving written recommendations from an expert, at least in relation to therisks and damages that could result from a possible accidental failure.

3.6.4 Operation and process control

Nowadays, automatic process operation and control are taken for grantedfor nearly every new chemical plant. The design techniques and the hard-ware selection are well advanced; however, the correct design is criticallydependant on the input of

process experts with industrial experience

on thefollowing issues.

• What are the more efficient procedures for

starting

and

stopping

ofthe plant? These transient procedures are not obvious, and they arenot always well covered in the basic designs. They have to be care-



fully thought out for every new process and for every installation inparticular, as they determine the internal inventories of the bufferingtanks, or the need for recycling certain streams, or for reprocessingsome bulky intermediate streams. These transient procedures arebased mostly on

kinetic response data

, which may have to be measuredexperimentally, or inferred from previous reliable industrial experi-ence in similar situations.

• How to assure a safe response to

any possible failure

of some equip-ment or a possible error in the action of an operator, limiting the risksand damages.

• What is the better choice for reliable probes and instruments in

directcontact

with the process streams, which are made of suitable materialsand can be available and supplied off-the-shelf?

3.7 Support from experts in software

3.7.1 Publication search and analysis

Obviously, the cheapest and fastest part of the R&D effort is to retrieve practicallyeverything that has been published on all the different factors relevant to theproposed process. This publications search can be subcontracted to specialistsor academic libraries where it is done by computer screening of large databases,according to agreed

key words.

The search output is a long list of published itemswith titles, address, and, in some cases, abstracts. In order to keep this outputin a manageable volume, one should be careful in the choice of these key wordsor, preferably, start exploring with a trial-and-error iterative procedure.

The resulting references can be first sorted and divided by the R&D teaminto two categories: those that were published because the authors consid-ered the new information to be of considerable scientific interest (of course),but with no commercial value, and those that were patented.

The collection of workable copies of the preselected publications can besubcontracted to specialized organizations, and sometimes can be lengthyand expensive, since most of the

comprehensive

experimental data was pub-lished long ago when the competition for journal space was not so intense.Unfortunately, in more recent publications, new experimental data are moreoften presented as

small

figures

that can hardly be used as sources for numer-ical data correlation. If a set of such data appears to be important enough,one could try to locate the authors and ask them for a copy of their originalnumerical data. It was observed that most authors were more responsivewhen such a request came from an academic researcher than from a com-mercial company. Some publications also need to be translated.

The senior R&D team should devote an analytical effort to the study ofthese publications and of their results, and possibly to the numerical corre-lation of the included experimental data, if needed. In addition to the factualinformation on the data, such analysis may give the senior R&D team someinteresting hints about:



• Reasons that initiated such previous research work•

Strategic aim

s of the authors and their supporters• Why they didn’t succeed in this aim on the industrial scale up until now

After the distribution of this survey and analysis to the core team andtheir relevant consultants, a

thorough discussion

can be very useful

before

deciding and starting on any significant experimental program.

3.7.2 Intellectual property and secrecy

If one accepts for a fact that the novel industrial process under

considerationis important and needed on the market, one must also assume that the com-petition is also looking at new processes of their own, which could be quiteclose to the one proposed in this project.

Everyone in this activity is trying to keep his own programs secret foras long as possible. (“Confidential” may be a nicer word) Every corporationhas its own secrecy procedures and all its employees, consultants, and con-tractors are generally signed to extensive formal secrecy obligations. But itshould be recognized that such signed undertaking is mostly of a moralnature, since it would be practically impossible to enforce, particularly withdissatisfied participants.

Thus, some corporations sometimes add restrictions on the internal flowof process information, on a need-to-know basis (limited distribution lists),which is a normal practice in certain business departments. Such restrictionshave been shown to be very detrimental to a process development team, whereall members should be talking freely among themselves while contributingto a common goal. These “limited distribution lists” can have clearly negativeeffects on the motivations and efficiency of certain members who may feelpersonally insulted, such as, “they don’t trust me.”

In the final instance, there is no alternative in this kind of activity butto work with reliable, well-motivated, and satisfied individuals.

3.7.3 Patent application

If another corporation has already filed a patent application that could pre-vent the implementation of the proposed process, this should be known asearly as possible, so that the claims of such an application can be avoidedand possibly by-passed. The real problem is that patent applications aremade public only 2 to 3 years after their filing date, and most patent attorneyscan use perfectly legal tactics to extend this period.

The issues affecting the patent filing strategy are complex and all derivefrom the potential menace of “the competition:”

1. The promoters (inventors) need the patent award as proof of the noveltyof their proposed process and of their intellectual property, partly fortheir self-satisfaction, but mostly as a necessary condition and instru-



ment which will allow them to sell and transmit the process to theimplementing corporation. Note that the patent office’s checking andawarding means only that no public information or previous patentclaim has been recorded, but it does not state that the process willwork as claimed or that it has any practical usefulness.The filing dateof the application is an important asset, but it is also a limitation,since it sets the procedural mechanism in motion. When the patentis awarded, the inventors have to decide within a short fixed periodabout the other countries where they need to apply for and record theapplication at their own significant expenses. Most importantly, apatent application represents the best extrapolation of what wasknown to the inventors at that particular filing date. Such extrapo-lation includes the purposeful addition, into the claims, of conditionsthat have not yet been proven, but are expected to give, more or less,similar results, e.g., a larger group of reagents or solvents, a widerrange of operating conditions, and so forth. As the inventors willprobably continue to work after filing their application and couldarrive at “better” claims later, they would have to decide whether itis worthwhile to cancel the previous application (and lose their pri-ority date) and file a new application with the better claims.

2. The management of the implementing corporation needs a strong patentto justify and protect the company’s significant investment. They alsoare interested in securing the widest possible coverage, both in substanceand in countries worldwide. But if the corporation managers were notpart of the decision-making on this subject at an early enough stage,they will have a complex choice when they take over, between filingan additional patent application, or canceling the previous applicationand reapplying, or accepting what has already been done.

3. The consultations with expert patent attorneys are concentrated mostlyaround the legal procedural options and the exact wording in theapplication. There is a specific professional “jargon” which is appar-ently mandatory in all relations with patent offices. However, thereis an element of risk as to the extent of coverage in the claims, which isthe exact definition of what is claimed to be new and exclusive tothis patent. A larger coverage in the claims may weaken their exclu-sivity position and could be more difficult to secure (that is to con-vince the patent examiner). A narrower coverage may be held stron-ger, but could be easier to by-pass. This coverage has to be decidedby the inventors, possibly with the input of the project management(if there is any at this point) with respect to the possible competition.

3.7.4 Process modeling

Process mathematical modeling has been one of the main advance fronts inchemical engineering research and development since the 1980s, with excellenttheoretical books and computer programs available. Today, this mathematical



modeling can be a useful tool in process development in many cases. Morespecifically, it can be useful if the relevant numerical data can be made avail-able or can be reasonably inferred from precedents. This possibility can makea lot of difference in the entire program.

Thus, the contribution of an expert in this field is needed, at an earlystage, to draft a model from the principal elements of the process definitionand to define exactly which numerical data will be required to make theperformance and results of such a model significant. (This is discussedfurther in Chapter 9, Section 9.5.)

3.8 Safety, public regulations, and waste disposal support3.8.1 Safety

Most chemical plants present some form of known safety hazards which arekept well under control. All of the chemical industry is living with this inher-ent characteristic. The implementation of a new industrial chemical processcan introduce a different safety hazard that was not previously known in theoperation practice of this particular corporation, although it is probablyfamiliar to other parts of the chemical industry. This potential safety hazardcan be due to the composition of the raw materials or of the reagents (i.e.,metallic impurities, organic solvent, and acids) or to the operation conditions(i.e., flash point, pressure, etc.). For example, an engineering requirement inthe early large-scale implementation of solvent extraction processes in thechemical, mineral, hydro-metallurgy, and food industries specified the“explosion-proof” safety standards, which were already well developed andused in the petrochemical industry for years.

There are very experienced safety consultants around who are availableto inform and reassure the project team in this field and to prepare the differentmanuals needed for the lab, the pilot operation, and the full-scale plant. Sys-tematic surveys and consultations with one of these safety experts are neededto identify such potential safety issues early in the development program andto document them in detail. Any public regulations relevant to such hazardsin the area of implementation should also be well understood.

This information should allow to include any necessary requirement intothe process definition and the plant’s future design and control, and to assurea safe operation. For instance, certain parts of the process and of the plantcan be declared as “explosion-proof” areas, separated and designed/operatedaccordingly, while other parts can be located far enough and avoid suchadditional expenses. Needless to say, the insurance company will also beinquiring as to when an investment will be decided.

3.8.2. Public regulations

In present days, any industrial or commercial activity is subject to a score ofpublic regulations (laws, taxes, custom duties, permits, etc.) which are changing



quite often, particularly in the democratic countries. A manager in industrialR&D cannot expect to know all of these regulations just from reading thenewspapers or from personal experience. Lawyers and specialists should becommissioned for the task of collecting up-to-date information that is relevantto the project and organizing it into different files from which project manage-ment can decide what needs to be included into the working program.

3.8.3 Waste disposal

A critical aspect of any chemical project is the definition and quantification ofall the possible waste streams and of the general options for their disposal withinthe framework of the particular region considered. This should be addressedquite early in any development program. This is again a specialized activityincluding technical, commercial, and legal aspects. This should be dealt with incollaboration with suitable consultants to find at least one (but preferably more)acceptable and affordable disposal procedures for each waste stream.

3.9 Support of specific codes relevant to plant design and operation, and product quality

Many products have to conform to a client’s own purchasing specifications.However, certain groups of clients are buying on express condition that theproduct is fulfilling the requirements of specific “official” codes controlledby a suitable governmental regulation, e.g., a food-grade, reagent-grade, orpharmaceutical-grade product (i.e., the FDA in the U.S. sphere of influence).

Such codes are issued, controlled, and maintained generally by publicorganizations (mostly manufacturers, but also consumers), and they regulatenot only the final composition and packing of the product, but also the rawmaterials and additives used, and the conditions prevailing in the executionof most stages of the production.

For instance, the food-grade code specification dictates not only that allthe raw materials and additives introduced in the process should be of food-grade quality, but also that the conditions in every process stage should bedesigned and controlled to prevent contamination, oxidation, microbialactivity, etc. This code also details the routine quality control with verydetailed analyses and formal reporting and recording. External quality con-trol also is often required.

If such specific code can be relevant to the new process and/or to thenew product, it should be studied from the beginning by the marketing andanalytical professionals and well understood by the core team. In addition tothe general principles of the code, its practical implications may relate insome detail to the selection of raw materials, the plant design, or the analyticalcontrol. For example, it took one producer of food-grade phosphoric acidmany years to drop from 2 ppm arsenic in the product to less than l ppm,as required by the food-grade code.



3.10 EconomicsThe ability to do economic evaluations of investment and of operation costson the whole process or on a defined part of it is needed from the beginningin order to assist in the choice between alternative options. These economicevaluations can start with simple “order of magnitude” calculations, but canbecome increasingly complex as the project’s scope gains substance.

Therefore, one should assure from the onset of the project the contribu-tion of a specialized cost engineer, who will lay down standardized spread-sheets adapted to the particular framework of the project and collect theexact unit costs that should be used by the corporation at the intended site.

As the process and the implementation framework begins to firm up,the standard tools and the experienced staff of an engineering companyshould produce investment budgets and operating cost estimates with anaccuracy (plus/minus) margin starting at 30%. This can be progressivelyreduced to 15% in the final report.

3.11 Development expense budgetLast but not least in the list of essential resources needed is an expense budgetto cover all the development costs (salaries, transfers, suppliers, consultants,materials, patents, special equipment, etc.).

At the beginning, this budget has to come from the promoters’ ownsources. At a later stage, if the project can be incorporated in the form of alimited responsibility shares company, those investing in risk capital fundscan possibly be convinced to buy a certain portion if it looks promising andif the promoters have good personal records.

In certain countries, public funds can be procured as a partial contributionto specific industrial or scientific developments, mostly in the form of loansrepayable in case of economic success, with many conditions attached. This isgenerally a very lengthy procedure as always with public funds.

When an implementing corporation takes over the project, it covers thepast and future costs from its own financial resources, through one of manydifferent financial formulas. However, as every project is different and pastrecords can only be indicative, “the future is no longer what it used to be.” Theability to predict logically a future process development budget has always beena weak point, although this fact of life is not always admitted or even recog-nized. Most promoters naturally tend to be rather optimistic in that regard.

The only practical method, while consulting with all experienced partici-pants around, is to:

• Divide the development program into a number of functional periodswith specific aims.

• Define and estimate separately every possible cost item in each period.• Draw up a detailed list of every possible cost item.• Then add generous safety factors.




• The success of the development and implementation of a new chem-ical process depends mostly on the interactions and cooperation be-tween many critically important human factors.

• The core project group is expected to work as a team, so that all itsmembers have access to all the documents and are aware of all thefacts, and each can contribute his opinion freely inside the team.

• There is generally a direct link between the accuracy of the resultsfrom analyses and the unit cost and time delay. The highest level ofaccuracy is not always justified and affordable for all results, partic-ularly in the exploratory stages of the R&D where a fast procedureis preferable.

• The accuracy and significance of the result from any chemical anal-ysis cannot be any better than the sampling procedure used to pro-cure the sample.

• The process development team should understand which features ofthe product are really important to the final users and what the finalusers would be ready to pay for these results if they were given thechoice between different qualities.

• The process developing team should get a clear and early picture ofthe eventual implementation conditions in an existing facility, whichcould impose objective limitations that need to be taken into account.

• In many cases, the design of a novel process section may be criticallylinked to one particular piece of equipment or specific technology,and the process results will depend not only on the process chemistry,but also on a particular combination of equipment design factors andof operating conditions.

References1. Mizrahi, J., People, organization, and process implementation, Chem. Tech.,

459–464, 1972.



chapter 4

Actual case examples

The following cases are given here only to the extentneeded to illustrate the general principles that are dis-cussed in this book. Obviously, the detailed account ofeach of these cases could have filled a book (assumingthat such details were allowed for publication). Theparticular cases chosen here come mostly from the au-thor’s direct experience, but are “old” cases, not anywith relevance to an ongoing operating corporation.

4.1 Nature and man: the Dead Sea

The Dead Sea is one of the world’s natural wonders; the deepest and one ofthe hottest places on Earth. During milleniums, it has accumulated chloridesand bromides of magnesium, calcium, sodium, and potassium. The averagecomposition of the sea brine reached a steady state, as the average yearlyamount of fresh water that was brought by the Jordan River into the DeadSea brine was equaled by the amount of water that had evaporated fromthis brine.

In the first half of the 20th century, processes were investigated to recoverthe potassium chloride from this brine as a vendable product (potash).Chemists at the Hebrew University in Jerusalem (M. Novominski, M. Lan-goski, and others) studied the entire relevant physical–chemical solids/liq-uid saturation system. They found that when the Dead Sea brine evaporatedand gradually concentrated in a

solar pond

, salt (sodium chloride) reachedfirst its saturation point and precipitated. Then carnallite (a hydrated doublesalt of magnesium and potassium chloride) was crystallized together withsome more sodium chloride. The scientists also found that the mixture ofthe carnallite crystals and sodium chloride, obtained from solar ponds, couldbe leached at ambient temperatures with a large amount of water to leavea number of fine potash crystals with a rather low yield. Or the mixturecould be leached alternatively with a limited amount of water at a highertemperature to decompose the carnallite and dissolve all the magnesium



chloride, allowing to separate by filtration the remaining solid sodium andpotassium chlorides. These can be hot-leached and then the hot filtrate brinecan be cooled and concentrated under vacuum in conventional equipmentto crystallize the potash. The remaining brine can be recycled back into thesolar pond to repeat the process.

1

This straightforward process was eventually developed and an indus-trial plant was built to produce potash at the southern end of the Dead Seanear the biblical site of Sodom. The plant included the following successivesections (see the excellent description by J. Epstein, Reference 2): large solarponds for salt, solar ponds for carnallite,

wet harvesting

of the crystals fromthe carnallite, solids–brine separation, decomposition of carnallite in twocountercurrent stages, hot leaching of the solids in a circulating brine, hotfiltration of the salt, vacuum cooling crystallizers, potash washing and dry-ing, and all the adjacent services required for a desert location. In this firstventure, the solar ponds with

wet-harvesting

were, indeed, the critical newelement essential to efficiently handle millions of tons per year of corrosiveslurry. This was done with floating dredges that crisscrossed the ponds,slurrying the crystals from the bottom, and pumping the slurry into a floatingpipeline to the shore.

But as we said at the beginning, this is a changing world and two

human-induced changes

, which were outside the control of the operating Dead SeaPotash Company, occurred later and required new process developments.First, starting from the 1950s,

all the fresh water

from the Jordan River wasdiverted for agriculture development in Israel and Jordan, and practically

no water

was allowed to drain anymore into the Dead Sea. The age-oldsteady-state was ended and the concentration of the Dead Sea brine startedto increase,

slowly but inexorably

with more salt precipitated at the bottom ofthe sea and, consequently, the carnallite

production

of the existing solar ponds

increased

. The trend of these changes could be followed, analyzed, and pre-dicted exactly from the 1960s, and since it was imperative that

all

crystalsproduced in the carnallite solar ponds be removed to avoid clogging thewhole system, it meant that the potash production capacity should be

increased

accordingly. Finally, this additional raw material was availablealmost for free, so why not build more potash production in the 1970s?

But when expansion plans were prepared and approved and their execu-tion was about to start, the so-called

“energy crisis”

of 1973 happened and thecost of thermal energy jumped almost overnight by a factor of four to fivetimes. With the new production costs and the uncertainty concerning thefuture situation in this regard, the additional potash production by the hotleach process could possibly lose money. So the

processes basic concepts

had tobe urgently reconsidered, including the potential use of some elements whichwere known but not considered essential in the previous economic context.

It was known, for example, that in the crystals mixture produced in thesolar ponds, the salt and the carnallite were precipitated practically in sep-arate crystals, and that the size distribution of the carnallite crystals wasrelatively coarser than that of the salt crystals. It was possible to separate



about 25 to 30% of the carnallite, in rather pure form, from the feed to thepotash plant just by coarse wet-sieving of the slurry.

It also was known for a long time that, when a controlled quantity ofwater is added to carnallite crystals at ambient temperature, all the magne-sium chloride would go into a solution with about 20 to 25% of potassiumchloride, leaving the remaining potassium chloride as fine solids. There wereno incentives to make use of this information up to that point, since it wouldhave only complicated the straightforward “hot leach” process. But whenseverly pressed by the energy crisis, its reconsideration allowed a corporatetask force to develop a “

cold crystallization”

process, which required almostno thermal energy.

From a carnallite stream with a relatively small salt content, a

cold crys-tallization

system would produce

reasonably coarse and clean

potash crystalswithout heating and cooling. This process was analyzed in detail and itsimplementation depended on the development of a

novel type of continuousindustrial reactor–crystallizer

, in which the rather pure carnallite solids werefed and dissolved in one part, while the potash was crystallized in anotherpart, solids were decanted in quiet zones and brine was circulated betweenthe different parts.

3

This new design was piloted and demonstrated in an intensive program.The crystal mixture pumped from the carnallite ponds to feed the existinghot leach potash plant was first wet-screened to separate as much as possiblethe coarse carnallite fraction. A first cold crystallization plant was success-fully build for several hundred thousands ton per year of potash. This newdevelopment allowed a few years of breathing time in the race against natureand the oil “lords.”

Then, the gist of the problem was proposed to the physical mineral sep-arations scientists. Given a crystal mixture of carnallite (specific gravity 1.6)with salt (specific gravity 2.1) in a slurry with

end brine

, a residual solar pondby-product from the potash production of Dead Sea brine (in fact, a concen-trated solution of magnesium chloride with a specific gravity 1.35), how canone

separate

a greater part

of the carnallite in a

reasonable pure form

, in millionsof tons per years, and at

very low cost

? This physical separation did not haveto be completed, since the remaining mixture could still be treated by hotleach, but the content of the

pure

carnallite fraction should be above 95%.This challenge was again solved by a novel technology: by

centrifugaljigging

on a tumbler centrifuge equipped with a conical wedge-wire screenwith a rather large aperture. This type of centrifuge was developed earlierin Germany as a large-capacity screening device to produce low moisturecoarse salt cakes. It was found that the pulsations in the expanded fluid bedof crystals, flowing on the inside of the conical wedge-wire screen, causedthe heavier salt crystals to concentrate nearer the screen and, thus have thepriority of passage through, leaving most of the lighter carnallite crystalsbehind. The large-scale application of this technology allowed anotherexpansion of the “cold crystallization” plant and more breathing time in thecontinuing race against the clogging of the solar ponds.



Finally, the separation of the salt from carnallite in the finer size frac-tions was obtained by adaptation of the conventional froth-flotation tech-nology for salt used in other lands, to the particular conditions of the DeadSea chemistry. Today, the multimillion tons per year production of potashfrom the Dead Sea is

using all of these originally developed technologies

in anoptimum combination.

4.2 Magnesium chloride-based industries

In the early 1960s, it was apparent that end brine was a raw material verysuitable for the production of magnesium oxide (MgO = periclase). Thismaterial is widely used for refractory bricks. Up to that time, a part ofsmall deposits of natural magnesium carbonate, all the existing worldproduction of this material was based on precipitation of magnesiumhydroxide from sea bitterns. Such production is done in a

very dilute system

with hydrated calcined lime, which is an energy-intensive raw material.The application of a similar technology to the Dead Sea end brine woulddeny any advantage of its higher concentration, leaving only the disad-vantages of a desert location.

On the other hand, it was known that the thermal decomposition of suchend brine can produce solid magnesium oxide and a vapor phase with awater/hydrochloric acid mixture. The detailed conditions required to conductcontinuously such thermal decomposition processes were studied by Dr. J.Aman from the Hebrew University in Jerusalem, who developed and patentedin the 1950s the

direct-contact

continuous “Aman reactor.”

4

This is a sort ofspray dryer (vertical cylindrical/conical chamber) in which the end brine issprayed at certain locations from the top while hot flue gases at 800 to 900

°

Care introduced tangentially at the middle height, creating a definite

internalflow pattern

. The solid impure MgO particles remaining from the liquid dropsare settled and removed from the lower conical outlet and the gases exitingfrom the top are directed to a direct-contact absorption column, producing a18 to 20% HCl solution (somewhat below the 22% azeothropic concentration).

This novel process was piloted in the 1960s, and its enormous industrial

potential

was then demonstrated. However, its implementation remainedcritically dependent on the economic utilization of the HCl by-product and,thus, it was delayed until a proper combination could be organized. Otherissues were connected to the presence of smaller quantities of magnesiumbromide in the brine, which would produce elementary bromine in the gases,and this needed to be dealt with. This started a solvent extraction processfor separating a stream of pure magnesium bromide from the end brine, butthis is a different story.

Note that the same Aman process technology was also licensed andapplied successfully in other countries by the Ruthner Company for thedecomposition of the

iron chloride

solution resulting from steel picklingplants, where the recovered HCl solution could be recycled and reused onsite in the pickling plant.



4.3 Economic uses for the HCl by-product solutions

4.3.1 Strategic policy

In the 1960s, the managing team of the IMI Institute for R&D, directed byDr. A. Baniel, created a corporate

strategic policy

defining the need of devel-oping

economic uses

for by-product HCl solutions. As part of the Amanprocess for magnesia, a number of promising “acid-salt” double decompo-sition processes were under consideration aimed at upgrading the value ofthe chlorides of potassium, sodium, and magnesium (available in very largequantities at low cost) into the relevant sulfate, phosphate, or nitrate salts.Implementation of any one of these potential processes would also yieldHCl as a by-product solution (as indeed, the IMI process for potassiumnitrate when it was implemented by Haifa Chemicals Co.).

5

Up to that time, HCl was mainly a traditional by-product of organicchlorination reactions and of small-scale chemical industries. In most of thesecases, the HCl was wasted, neutralized with lime and/or limestone, anddisposed of as CaCl

2

in the sea. Only in very large organic chlorinating instal-lations could the HCl by-product be collected as a solution and recycled to anelectrolysis section to regenerate elementary chlorine, or collected and recycledby the Kellog’s Kel-Chlor process.

6

This route was hardly more economical,but it was possibly less problematic than the neutralization route.

4.3.2 Coupling of HCl-producing and consuming plants

Some industrial uses with economic justification were developed within thisstrategy (see discussion below), but the

basic problem

that remained for sev-eral decades was the

critical coupling

in the implementation between the plant

producing

the HCl and the plant

consuming

it, in their geographical location,in quantity, and in timing. It should be remembered that the HCl–watersystem is dominated by an

azeotrope

at 20 to 22% HCl, so that every ton ofHCl generated below the azeothrope is accompanied over the fence by 4 to5 tons of water, and the transportation of such solutions would be impracticalover any significant distance.

“Breaking the azeothrope” (i.e., obtaining more concentrated solutionsor even 100% dry HCl) is possible, but complicated and expensive, both ininvestment and in energy consumption; for example, by using a cycle ofCaCl

2

brine. This was a wide field of creative process design, aiming at abetter use of the energy and expensive heat exchangers, and for possiblesynergetic utilization of sources of low-temperature waste heat.

7

(See alsoChapter 6, Section 4.)

4.3.3 Timing of implementation

As an acid reagent, HCl could be used to replace sulfuric acid in severalmineral industries. Some new processes in hydrometallurgy and mineralrefining were studied and a few of these could have been developed and



used if a reliable HCl source could have been made

available at the right time

;for example, the cleaning of sand for the glass industry, the purification ofdifferent sorts of clays, the reprocessing of nonferrous scraps, etc.

4.3.4 Production of pure phosphoric acid

The main novel process that was actually developed and used on a largescale in several plants was the production of

phosphoric acid

by hydrochloricacid leaching of (calcium) phosphate rock. The conventional process with

sulfuric acid

gives a

solid gypsum

residue, which is separated by filtration fromthe

impure

“wet”

phosphoric acid (WPA) solution. There exists also processesbased on nitric acid.

When using a hydrochloric acid solution to dissolve the phosphate rock,the water-soluble residual CaCl

2

remains in the same aqueous solution withthe phosphoric acid. A new separation process, therefore, was required toisolate the phosphoric acid from the CaCl

2

(and all the other soluble impu-rities). This result was provided in a pioneering breakthrough by A. Banieland R. Blumberg, by way of solvent extraction.

The first IMI “standard” phosphoric acid process was quite complexwith six different multistage, countercurrent batteries. A comprehensivedescription of all the issues related to its development and implementationwas presented at an international scientific conference,

5

as an

IMI staff report

prepared by a dozen senior staff members, each one in his/her specialty.This

unique

approach started in this book, but unfortunately it was not wellunderstood and was not pursued in further scientific publications.

The new process also accomplished a thorough

purification

of the phos-phoric acid product, which could aim at the higher value markets. Suchmarkets were traditionally supplied by “thermal” phosphoric acid, obtainedvia elementary phosphorus (see below). This novel process was actuallylicensed and implemented first in Japan, Brazil, and Spain, where someexisting sources of by-product HCl already existed, before it was used inIsrael in large plants fed with HCl by-product from potassium nitrate andpericlase productions.

4.3.5 Technological difficulties

After the basic chemical research and the bench-scale demonstration of thenew process, the developing team at the IMI Institute for R&D had to facesome difficult

technological

issues on the way to implementation.

4.3.5.1 Materials of construction

HCl is a well-known, “nasty” component to work with, as it attacks practi-cally any metal. Previously, it could be handled in industry only in smallglass equipment (i.e., Pyrex), or small glass-lined steel (i.e., Pfaudler), or insome cases, in rubber-lined steel (limited to the lower temperature range ofless than 60

°

C). As all of these options for materials of construction were



very expensive, sensitive, and quite limiting in large volumes, it was obviousfrom the start that plants for the large-scale production of relatively cheapmaterials could not be built exclusively from expensive materials.

Fortunately, during the same period, the technology for the design anderection of large equipment and piping made from

plastic

was being devel-oped in several advanced industrial countries. This technology used sheetsand tubes of thermoplastic PVC and polyethylene (and, later, polypropylene)with possibly the external reinforcement of layers of glass-fiber/polyestersetting mixtures and of steel members. Later, the fabrication of equipmentmade exclusively from reinforced polyester or epoxy setting mixtures wasestablished. This new technology was the

critical engineering basis

for anyHCl-based industry at that

time. Thus, the process development group hadto take a very active role in locating the best know-how available worldwide,in establishing specialized companies and workshops in Israel, in creatingdesign standards and testing procedures, and in merging all of these into apractical working system. Another limitation was that the use of

plasticizer

materials in the thermoplastic material was strictly prohibited for all vesselscontaining solvents, as these plastisizers would be leached out by the solvent.(Today, this fabrication technology is essentially available widely as a stan-dard engineering choice, but there are continuing new improvements inmaterials and in design techniques that have to be evaluated.)

At the same time, it was obvious that the use of these thermoplasticmaterials would limit the process temperature to below 60

°

C (at most). Thus,any solvent stripping operating at higher temperatures would remain mostlywith conventional glass-lined equipment, although thermo-setting resinscould sometimes be used for limited functions, and should be minimized aspossible. Another prosaic but important limitation was that, for structuralstrength design considerations, all plastic vessels needed to be

round

(verticalcylinders) and this affected both the

internal functional

design and the plant’sgeneral layout considerations.

4.3.5.2 Safe, stable conditions for solvent extraction in large mineral plants

At the beginning of the project, the “explosion-proof” conditions associatedwith the handling of relatively large quantities of organic solvents withrather low ignition points (i.e., butanol, pentanol, and the like) were wellknown in petroleum refineries and petrochemical installations, but ratherunfamiliar in the mineral/chemical industry. The process developmentgroup had to recruit experienced consultants in this area and make a specialeffort to study, assimilate, and adapt the explosion-proof codes to theseparticular projects, even for such simple items as the venting of excess gases.

In addition, the composition of the solvent stock circulating in the plantcould hardly be taken as a constant, as it undertook various chemicaldegradations and additional reactions, mostly with the unavoidable impu-rities flowing through the plant streams. For example, most phosphate orescontain some organic matter soluble in acidic leach solutions, which are



partly extracted and accumulated in the solvent, and require specific clean-ing procedures.. Such reactions can produce contamination in the productor even change some of the solvent’s properties. Thus, a surprising amountof sophisticated R&D in

organic chemistry

was needed for such mineralprocess development.

4.3.5.3 Clean starting solution for solvent extraction

One of the main enemies of industrial solvent extraction is the

crud

consistingof fine solid precipitates, which accumulates at the interface between thetwo liquid phases and may prevent their separation and cause emulsions.This crud may also clog lines and build up in equipment.

When dissolving, for instance, a typical phosphate ore into a hydrochlo-ric acid solution (with minimum acid excess), most of it goes into a solution.The resulting slurry is degassed under vacuum and the solid residue (con-sisting of sand, clays, dirt, etc.) is then flocculated and separated by coun-tercurrent decantation, and the overflow is polished by filtration. This is theeasy conventional part. However, when the

clear filtrate solution

comes incontact with the organic solvent, the solubility conditions change, and it wasoften found that

crud would precipitate

.For example, part of this crud can be

organic colloidal material

originatingfrom the natural phosphate ore, which was maintained completely in solu-tion in the strongly acid solution, but can be precipitated when part of theacid is extracted and flocculated by the organic reagent. Other parts of thiscrud can be mineral or

metallic salts,

which were initially kept in solution bythe strong acidity. As these elements were defined, the process developmentteam had to devise ways to avoid this crud, or at least reduce it to proportionsthat could be handled with periodical cleaning schedules. This aim could beachieved by either changing the properties of the starting phosphate ore, ifthere was an affordable choice (e.g., by using a more expensive calcinedphosphate concentrate with no organic matter), or by adding pretreatments(such as ion exchange) to the solution before its transfer to the solventextraction section.

4.3.5.4 Recovery of the residual solvent from different exit streams

All the effective solvents were partially water-soluble, and their saturationsolubility in the exit aqueous streams was of the order of a few percents,depending on the temperature and on the other solutes presents. In principle,these residual solvents could be stripped down to the allowed and affordablelevel of, say, less than 100 ppm in a distillation column with sufficient numberof stages and reflux. Again, this may seem a trivial question of engineering,but it was rapidly apparent to the process development team that the invest-ment on the glass-lined equipment, the possible attack of fluoride anions onthe glass lining, the possible deposition of calcium fluoride from wastesolutions whenever heated, and the associated thermal energy and coolingwater would be a

critical load

on the economics.



Thus, every possible way to decrease these costs had to be consideredin the process development. The overall technical–economical optimizationcould recommend a different solvent, which possibly may have been lesseffective in the separation, but cheaper to recover. Other practical questionsalso needed to be addressed, such as the possible fouling of the highertemperature stripping equipment with solid incrustations and, in particular,on the heat exchanger surfaces.

4.3.5.5 Large-capacity liquid–liquid contacting equipment

The implementation of the new processes required

large-capacity

liquid–liq-uid contacting equipment

8–23

for multiple-stage countercurrent batteriesmade of suitable materials, i.e., plastic (see above). The concept of the mixers-settlers was already established on bench scale and used in pilots and rela-tively small industrial installations (i.e., for uranium extraction). However,the design of

efficient large-scale equipment

was not established at the timeand some issues had to be solved.

First of all, hydraulic heads for the flow of liquid streams from stage-to-stage in both directions had to be worked out. The simplest solution formaintaining such hydraulic heads is to install two interstage pumps for eachstage (with the associated sumps and level controls, but with very lowheads), which, in addition to the mixer, amounts to three explosion-proofmotors per stage. No problem. One has only to multiply the number of stagesby three, but the result is not a simple number, but more likely a snowball.The cost of an explosion-proof motor is 2 to 3 times that of an ordinary one,but its installation can cost 10 times more, and the level control loop willdouble that total. One alternative can be to design with only one transferpump, plus a difference in height, but this difference would accumulate andcertainly complicate the vertical layout for large multistage batteries. There-fore, to keep all the mixers–settlers on the same level with only one motorper stage, there was a clear and imperative need to use each motor for morethan one task. This prompted from the beginning a

hydraulic

research anddevelopment program as an integral part of the new chemical process imple-mentation on a large scale.

Figure 4.1 illustrates the principle of the patented IMI “pump-mix” con-cept, with a vertical pump (between two static baffles) on the same shaftand above the mixing axial propeller. This pump design has a very steep {Q@ H} curve, so that the level in the mixer is self-regulated without any levelcontrol hardware. A manual weir for each ratio of liquid densities fixes thelevel of the apparent interface in the settler. This design was successfullyinstalled in a large number of industrial installations for those cases wheretwo liquid phases had relatively close densities and low viscosity and couldbe easily dispersed and circulated in the liquid–liquid mixer. A reasonablemass transfer was obtained with the large range of droplet sizes.

But at a later stage, when implementing such processes involving thecontact and equilibration of a

heavy aqueous brine

with a

light organic solvent

,the above design could no longer give the adequate hydraulic heads, mass



transfer, and phase separation rate. So, as an integral part of these newprocess developments, a new liquid–liquid mixer had to be designed andtested, resulting in the IMI “turbine pump mix” design (see Figure 4.2),which produced a

controlled

droplet distribution when operated with a

vari-able speed

drive.Finally, the use of plastic materials of construction also necessitated

the functional design of a relatively

new round settler

(instead of the con-ventional “shoebox” design), with a central inlet of the two liquid-sus-pension from the mixer, and radial flow of all separated phases. Thisdesign required a fundamental study of the basic hydraulics connected tothe settling coalescence process and of quantitative design procedures forsuch a settler. This study resulted in a later stage to the invention of thepatented “compact settler” design, making use of racks of inclined parti-tions to save the largest part of the area and of the internal volume, andreduce the expensive solvent inventory. (See also Chapter 6, Section 6.4.1and Figures 6.5 and 6.6.)

Figure 4.1

Mixer-settler with pump mix.

Figure 4.2

Mixer-settler with turbine pump mix.

apparentinterface

heavy phase

heavyphase

lightphase

vent

lightin

heavyin

mixed phase

weir

apparentinterface

heavy phase

heavyphase

lightphase

vent

light in

heavy in

mixedphase

tangentialconnection

light phase

turbine

stator

weir



4.4 Phosphoric acid diversification processes

4.4.1 Different quality specifications

The different users of phosphoric acid require

different quality specs

, which arelisted below in order of decreasing purity and purchase cost per unit of P

2

O

5

:

1. Chemically pure/pharmaceutical grade (CP or PG)2. Food grade — FGPA3. Technical grade — for different phosphate salts4. Animal feed grade — for cattle and poultry feed supplements5. Detergent grade — mostly for sodium tripolyphosphate (STPP and

similar)6. Liquid fertilizer grade — giving a clear aqueous solution after neu-

tralization7. Solid fertilizer grade — lowest acceptable grade (almost anything goes)

4.4.2 Solvent extraction opening

Up to the introduction of the solvent extraction processes in several coun-tries,

24,25

there were only two grades of phosphoric acid available:

• The wet process acid (WPA) that was adequate only for the solidfertilizer grade, as it contained a few percents of sulfuric acid, someF, Ca, Mg, Fe, Al, etc.

• Expensive “thermal acid,” which should be used for any of theother grades.

The production of thermal acid (and these markets) was limited not onlyby its cost (2 to 3 times more than WPA), but also by the serious ecologicalhazards related to the elementary phosphorus. The

unfulfilled potential

and

the needs

were clear to the whole industry. Various chemical treatments werestarted in various places in connection with specific partial neutralizationprocesses of WPA.

As soon as the solvent extraction technology got established worldwideand the phosphoric acid extraction and purification was demonstrated,

26–27

there was a worldwide rush by R&D units in this industry to establish newprocesses, to patent different related issues, and to build producing plants.28

The solvent extraction technology allowed for producing different qualitygrades of phosphoric acid at varying production costs, starting with the mer-chant qualities of WPA, which could be produced on site or be purchased. Butone should also note that any one of these processes would leave a more impureresidual stream containing between 30 and 70% of the starting phosphatevalues. This should be downgraded and compounded into a solid fertilizer-grade by-product or mixed, if possible, with merchant WPA. This meant thattheir implementation could only be in proximity to a large solid fertilizer plant.



There was a very intensive worldwide struggle in the 1960s and 1970suntil the novelty appeared to be more or less exhausted and the worldwidemarket saturated; this despite a very fast increase in the demand for the prod-ucts, mostly for the detergent and liquid fertilizer uses. (The Tennessee ValleyAuthority [TVA] point of view is summarized in Reference 29.)

Following are some of the processes developed by the IMI team in thisparticular field.

4.4.3 IMI “cleaning” process

The IMI “cleaning” process30 was implemented in 1974 in a large plant thatis still functioning in the port town of Coatzacoalcas in southern Mexico,near a large WPA producer. The solvent extraction process is extremelysimple and flexible and is based on the extraction of phosphoric acid from a53 to 54% P2O5 WPA feed with a diisopropylether (IPE) organic stream at alower temperature and its back extraction at a higher temperature as cleanproduct. This is at a concentration of 50% P2O5, which is used either fordetergent grade or for liquid fertilizer grade.

The novelty of this process, which is quite unique, is that each operationis conducted in a temperature-controlled invariant system, in which three liquidphases with fixed compositions coexist in the zone delimited by the points:

A. Light phase, almost only IPEB. Intermediate zone with a relatively high solubility of phosphoric acidC. Heavy aqueous solution with very little IPE, as shown in Figure 4.3

on a triangular equilibrium diagram for the tertiary system phospho-ric acid-water-IPE

Figure 4.3 Triangular equilibrium diagram H3PO4-water-IPE.

H2O H3PO4

IPE

WPA

A

B

C



Without this particular feature, IPE would be a quite inefficient solvent. But theWPA is mixed with the recycled solvent in a weight ratio such that thetotal mixture composition fell into the three liquids zone, as close as possibleto the line BC. An extract B is separated and most of the impurities remainwith the residual C. Some water is then added to the extract to separate italong the line AC, which will give the Clean Acid(c) and the recycledsolvent (A). All the mass transfer and the final results are obtained in asingle equilibrium stage for each operation (for a fixed number of components,more phases at equilibrium = less degrees of freedom = simpler process, as Gibbswould have said), although a second mixer-settler was provided in the plantas backup and energy optimization. However, small amounts of the cat-ionic impurities and sulfuric acid entering with the feed WPA (more com-ponents) are co-extracted and can be reduced to the extent needed by acountercurrent, backwash reflux battery.

About 60% of the phosphoric acid is recovered as “clean acid,” whilethe “residual acid” containing 40% P2O5 (with most of the impurities) isreturned and back-mixed into the fertilizer plant. The traces of the volatilesolvent are removed from the two exit streams in two steam-stripping dis-tillation columns.

4.4.4 “Close-cycle” purification process

The IMI “close-cycle” purification process31,32 to produce a quite pure phos-phoric acid from WPA was a modification of the “standard” process in whichthe CaCl2-rejected solution was concentrated, roughly cleaned, and recycledto be mixed with the WPA feed. The rest of the process was similar. Thisallowed by-passing the situation where HCl was not available. The processworked well and the product was very pure, but the process was quitecomplicated. Several studies by large corporations showed that it could bejustified economically only if it was implemented on a very large scale. Suchscale exceeded the demand for such pure product in most geographical areas.

4.4.5 Mixed process

A mixed process is practiced in Israel by mixing a certain portion of WPA(at a 28 to 30% P2O5 solution before its final concentration) into the HClleach operation in which the phosphate concentrate is dissolved. Suchaddition increase the average concentration of P2O5 in the leach solutionand makes use of the acidity of the sulfuric acid in the WPA. The sulfateprecipitates as gypsum with other impurities before the filtration of thesolid residue. Straight sulfuric acid can also be used, but this wouldincreases the load of gypsum on the filter, which needs to be HCl-resistantin such cases. The “mixed” process is then operated in the same way asthe “standard” process, but in a more concentrated and cost-efficient way.It also avoids the restrictions caused by the limited supply of HCl and thelow concentration of its solution.



4.4.6 New proposals

New processes for phosphoric acid published since the 1990s included oenfor obtaining phosphoric acid from phosphate rock and hydrochloric acid viaferric phosphate, which was patented in 1997 and published at the Interna-tional Solvent Extraction Conference (ISEC) in 1999.33 It aimed at cutting dras-tically the volumes and number of contact stages involved in the standard IMIprocess, at the cost of a couple of solid–liquid separations by using the verylow solubility of ferric phosphate (see also Chapter 5, Figure 5.1).

4.5 Citric acid by fermentation and solvent extraction4.5.1 Conventional lime sulfuric acid process for citric acid

Citric acid is an expensive but widely used food additive, giving acidity andlemon flavor to industrial food and soft drink products. Sodium citrate isalso much used as a detergent component for domestic laundry and in manypharmaceutic and fine chemical products. Citric acid is produced by aerobicfermentation in deep tanks, starting with a carbohydrate solution containingdifferent additives and seeded microorganisms. After the practical comple-tion of the fermentation and the filtration of the suspended material, thecitric acid contained in the fermentation “broth” needs to be separated fromany residual carbohydrates and from all the various impurities and by-products, in a form suitable to produce pure citric acid crystals.

The chemical separation route used by most producers consisted, in theaddition of hydrated lime (“liming”), the precipitation of calcium citrate,the filtration and washing of the solids, then the decomposition of the filtercake in a sulfuric acid solution in a strictly controlled ratio to liberate thecitric acid and precipitate the calcium as gypsum. After filtering and wash-ing the gypsum, the solution is concentrated and the citric acid crystallized.The product crystals are washed and the wash solution returned to theconcentrator. The remaining mother liquor is bled and recycled back to theliming. While all producers are keeping confidential the details of theiroperating procedure, it is probable that they are also using additionalpurification steps on different streams, such as active carbon, adsorbingfilter aids, ion exchange, etc. This chemical separation route was used formany years, but is rather delicate to operate, as it had three solid–liquidseparations with washing, resulting in a relatively low citric recovery yield,a high consumption of many reagents, a costly waste disposal, and theoccasional dumping of contaminated batches. This was an obvious placefor a better separation process.

4.5.2 IMI-Miles solvent extraction process for citric acid

With the increasing understanding of the temperature effect on the revers-ible extraction/separation of mildly strong acids with tertiary amine



extracting agents, the IMI team, under Dr. A. Baniel, proposed in 197034 anew process to replace the chemical route described above. This was rap-idly developed, demonstrated, patented, and licensed to one of the majorproducers in those days, Miles Laboratories, Inc. The new process was thenpiloted and implemented in close cooperation with the Miles technicalteam, under Dr. Toby Wegrich, in an existing large plant in the U.S., affect-ing only those sections that were to be replaced. The satisfactory operationresulted in a much increased citric recovery (that relates to the plant pro-duction capacity) and in lower production costs. This process was thenused in other plants of the company, giving them a strong advantage overany competition worldwide.

4.5.3 Newer solvent extraction process for citric acid

About 20 years later, another large American corporation (Cargill, Inc.)decided to get into the citric acid business from the start. The company haddeveloped its own fermentation technology and knew, of course, about theIMI patent licensed to Miles (which was still in force), and were looking fora similar solution. Dr. A. Baniel and David Gonen provided this result in avery creative but simple way35 (which should be very instructive for futuresimilar cases).

The first process intended to use the fermentation broth as it wasproduced then in the existing Miles plants, so the attention of the devel-opers and the original patent claims were referred to this particular rangeof citric concentration. But the citric concentration can be increased 2 to 3times by evaporation, if needed, before the separation process. Such changeallowed not only to avoid the formal wording of the claims in the originalpatent, but also to take advantage of the higher concentrations to get amore compact and efficient separation process with relatively smallerequipment and less solvent inventory. This novel concept was rapidlydeveloped and demonstrated in close cooperation with the designatedcorporate task force. A large plant was built and operated very successfullyon this basis.

Why wasn’t this increase in concentration thought of and introduced inthe IMI-Miles process from the beginning? Only because the exact frameworkof allowed changes (in the existing and producing plant) were defined fromthe start as a precondition for the novel process design, to limit the risks thatthe implementing corporation would be ready to accept. Why wasn’t thisincrease in broth concentration studied and patented later by the operatingcompany after they had a working plant and complete control of the tech-nology? Because then, the common rule in industry was applied: “If it worksand makes a nice profit, don’t touch it.”

Twenty years later, starting with a confident new team and a blank sheet,this preconcentration was a perfectly normal option for consideration. Thislesson can be applied to many other processes.



4.6 Preparation of paper filler by ultra-fine wet grinding of white carbonate

White paper, made with “neutral/alkaline sizing,” contains between 20 and35% by weight of white filler powder, which is mostly precipitated calciumcarbonate in the form of crystalline needles. This filler gives to the finishedpaper its whiteness, opacity, and weight. Such precipitated calcium carbon-ate is not difficult to make, but it is energy-intensive and has to be producedon a relatively large scale. Thus it is relatively expensive, particularly if ithas to be dried, packaged, and transported for long distances. So, the eco-nomic need prompted the question: Why can’t it be replaced by finelyground, white calcium carbonate?

A new process technology was developed and implemented on a mod-erate scale near a large paper mill. This dedicated exclusive user wasreceiving the slurry in accordance with his own specification, ready to mixinto the feed going to the paper machine, naturally flocculated with aconsistent size distribution, characterized by an average size of 1 micron,with most smaller than 2 microns, and with a minimum content of minushalf a micron.36

The novelty and the particular features of the process technology, whichwas needed to obtain such final particles, were in the operating conditionof a regular iron ball mill, such as the pulp density, the residence time, thetemperature and certain chemical additives. However, since the final sizespecification cannot be obtained in a single pass, an extensive external circuitwas needed for fine-size classification, separating the product’s fine particlesfrom the recycled coarser particles. This circuit represented the main processchallenge, considering the requirement that the product particles should retaintheir natural flocculation. Generally, in the technology of “fine particles,”dispersing agents would be used to achieve such size classification, but theywere not allowed in this case.

The process solution was derived from the previous research work doneby one of the developers in the mechanism of hydrocyclones,37–40 whichallowed the design of batteries of microhydrocyclones in a countercurrentarrangement, handling large flows of diluted slurry (Figure 4.4). In addition,an original automatic control scheme was designed to handle the naturalfluctuations in the raw material and mechanical system, based on the con-tinuous measurement of the size distribution in the product slurry, which oper-ated a number of flow splitters affecting the recycle cycles. This lesson canbe applied to other similar microparticle systems.

These filler particles were more or less round, whereas the usual precip-itated calcium carbonate generally consists of elongated needles and thisaffected somewhat the “usual appearance” of the finished paper, althoughmost users were unable to perceive the difference. This ultra-fine grindingplant was happily operated by the Polichrom Company for about 12 years,but then the trading conditions in the area were changed, forcing the papermill to modify its line of products and its operating procedure.



4.7 Worth another thought• The use of the by-product from one process in one plant as a raw material

for another process in another plant creates a critical coupling betweenthe two plants, in geographical location, in quantities, and in timing.

• The implementation of a new process can also require new solutionsas regards materials of construction, design standards, and new func-tional equipment.

• The introduction of a new process to replace part of an existing plantis generally preconditioned into the existing conditions of the remain-ing sections. However, once it is well integrated into the production,an overall optimization should be studied for further improvementor future plants.

References1. Kenat, J., The production of potash from the Dead Sea, Second Symposium on

Salt, Cleveland, OH, 1965.2. Epstein, J.A., The recovery of potash from the Dead Sea, Chem. Ind., 572–576,

July 1977.

Figure 4.4 Principle of an ultra-fine wet grinding and classification process.

Ball Mill

solidfeed

centrifugefine

productslurry

waterrecycle

split

split

water



3. Tzisner, T., The Maklef plant for cold crystallization of potash, Comm. IsraelSoc. Chem. Eng., personal communication, October 1989.

4. Aman, J., British Patent 793.700, 1950; Israel Patent 8722, 1956.5. IMI Corporation, Development and Implementation of Solvent Extraction

Processes in the Chemical Industries, staff report at the Int. Solvent ExtractionConference, The Hague, 1386–1408, 1971.

6. Van Dijk, C.P. and Schreiner, W.C., Hydrogen chloride to chlorine via the Kel-Chlor process, Chem. Eng. Prog., 69, 57–61, 1973.

7. Mizrahi, J., Barnea, E., and Gottesman, E., Production of Concentrated HClfrom Aqueous Solutions Thereof, Israel Patent 36,304, 1972.

8. Mizrahi, J. and Barnea, E., A Gravitational Settler Vessel, Israel Patent 30,304, 1968.9. Mizrahi, J. and Barnea, E., A Liquid–Liquid Mixer, Israel Patent, 43,692, 1973.

10. Mizrahi, J. and Barnea, E., A Gravitational Settler, Israel Patent, 43,692, 1973.11. Barnea, E. and Mizrahi, J., Compact settler gives efficient separation of liq-

uid–liquid dispersions, Proc. Eng., 60–63, 1973.12. Barnea, E. and Mizrahi, J., A generalized approach to the fluid dynamics of

particulate systems, I: General correlation for fluidisation and sedimentationin solid multiparticle systems, J. Chem. Eng., 5, 171–189, 1973.

13. Mizrahi, J., Barnea, E., and Meyer, D., The Development of Efficient IndustrialMixer-Settlers, paper presented at the Int. Solvent Extraction Conference,Lyon, France, 1, 14l-168, l974,

14. Barnea, E. and Mizrahi, J., A generalized approach to the fluid dynamics ofparticulate systems, II: Sedimentation and fluidisation of clouds of sphericalliquid drops, Can. J. Chem. Eng., 53, 461–468, 1975.

15. Barnea, E. and Mizrahi, J., Separation mechanism of liquid-liquid dispersionsin a deep-layer gravity settler (four-parts series), I: The structure of the dis-persion band, II: Flow patterns of the dispersed and continuous phases withinthe dispersion band, III: Hindered settling and drop-to-drop coalescence inthe dispersion band, IV: Continuous settler characteristics, Trans. Inst. Chem.Eng., 53, 61–69, 70–74, 75–80, 83–93, 1975.

16. Barnea, E. and Mizrahi, J., A generalized approach to the fluid dynamics ofparticulate systems, II: Sedimentation and fluidisation of clouds of sphericalliquid drops, Can. J. Chem. Eng., 53, 461–468, 1975.

17. Glasser, D., Arnold, D.R., Bryson, A.W., and Vieler, A., Aspects of mixerssettlers design, Min. Sci. Eng., 8, 23–31, 1976.

18. Barnea, E. and Mizrahi, J., On the “effective” viscosity of liquid-liquid dis-persions, I&EC Fundam., 120, 1976.

19. Barnea, E. and Mizrahi, J., The Effects of a Packed-Bed Diffuser Precoalesceron the Capacity of Simple Gravity Settlers and on Compact Settlers, paperpresented at the Int. Solvent Extraction Conference, Toronto, 374–384, 1977.

20. Barnea, E., The Application of Basic Principles and Models for Liquid Mixingand Separation to Some Special and Complex Mixer-Settler Design, paperpresented at the Int. Solvent Extraction Conference, Toronto, 347–355, 1977.

21. Barnea, E., Meyer, D., and Wahrman, D., Logical Design of Mixers, paperpresented at the Int. Solvent Extraction Conference, Liege, France, 6–12, 1980.

22. Harel, G., Kogan, M., Meyer, D., and Semiat, R., Mass Transfer Characteristicsof the IMI Turbine Pump-Mix, paper presented at the Int. Solvent ExtractionConference, Denver, 26–27, 1983.

23. Cusack, R. and Karr, A., Extractor Design and Specification, Chem. Eng.,113–118, 1991.



24. Toyo Soda Manufacturing Co., Japanese Patent 7,753, 1964.25. Albright and Wilson Ltd., German Patent Application, 2,320,877, 1973.26. Baniel, A. and Blumberg, R., in Phosphoric Acid, Slack, A.F., Ed., Vol.1, Part II,

Marcel Dekker, New York, 1968.27. Blumberg, R., Industrial extraction of phosphoric acid, Solv. Extrac. Rev., 1,

93–104, 1971.28. Blumberg, R., Meyer, D., and Mizrahi, J., Development and implementation

of solvent extraction processes in the chemical industries, paper presented atthe Int. Solvent Extraction Conference, The Hague, 1386–1408, 1971.

29. McCullough, J.F., Phosphoric acid purification: comparing the process choic-es, Chem. Eng., 101–103, 1976.

30. Mizrahi, J., IMI Technology for Cleaning Wet Process Phosphoric Acid bySolvent Extraction, paper presented at the Symp. Am. Chem. Soc., 1973. (Thedata in Figure 4.1 was included by Blumberg, R. in a communication to Isr.Chem. Eng. J., September 1973.)

31. Blumberg, R., Miscellaneous Inorganic Processes, in Handbook of Solvent Ex-traction, Lo, T.C., Baird, M.H.I., and Hanson, C., Eds., John Wiley & Sons, 827,1983.

32. Slack, A.V., Phosphoric Acid, Part 2, Marcel Dekker, New York, 721, 1968.33. Mizrahi, J., New Process for Phosphoric Acid from Phosphate Rock and

Hydrochloric Acid Via Ferric Phosphate, paper presented at the Int. SolventExtraction Conference, Barcelona, 1999; also Israel Patent Application,120,963, 1997.

34. Baniel, A., Bkumberg, R., Haidu, K., U.S. Patent 4,275,234, 1971.35. Baniel, A. and Gonen, D., European Patent 91304805, 28.5.91.36. Hirsch, M., Hirsch, I., and Mizrahi, J., Production of white carbonate paper-

fillers by a new ultra-fine wet grinding technology, Ind. Miner., 67–69, 1985.37. Mizrahi, J., Separation mechanisms in hydro-cyclone classifiers, Brit. Chem.

Eng., 10, 686–692, 1965.38. Cohen, E., Beaven, C.H.J., and Mizrahi, J., The residence time of mineral

particles in hydro-cyclones, Trans. Inst. Miner. Met. (London), 129–138, 1966.39. Mizrahi, J. and Cohen, J., Studies of factors influencing the action of hydro-

cyclones, Trans. Inst. Miner. Met. (London), 318–330, 1966.40. Mizrahi, J. and Goldberg, M., Computer simulation of unflocculated hindered

settling, Isr. J. Tech., 318–392, 1969.



chapter 5

Process definition and feasibility tests

The first review of the proposed idea was done inside the R&D group (seeChapter 2, Section 2.2.1). It was shown in that review that the process can“make sense,” did correspond to a real need, and, on the face of it, was notscientifically incorrect. As a result of these early consultations, a “green light”was given to the promoters’ group for the commissioning of the literaturesurvey, for the preparation of this preliminary process working definitionand for their formal presentation for a second review in a larger forum.

5.1 Translation of the idea into a process definition

5.1.1 Scope of the preliminary process definition

An essential

starting point

for any development program is a preliminaryprocess definition, which will allow:

• Bringing everybody concerned to an

explicit common reference basis

• Illustrating a

concrete venture

in order to develop the interest of thehard-nosed decision-makers in the continuation of the work

• Outlining a proper experimental program and starting its detaileddesign

This field of

synthesis and design of chemical processes

has been the subjectof a number of excellent

theoretical textbooks

.

1–4

These manuals can be usefulmostly for the analysis and understanding of the fundamental principles,and for the definition of

the data which would be needed

for the use of thesophisticated models available. Unfortunately, at the beginning of a newdevelopment program,

most of such data would have to be assumed

.Therefore, this preliminary process definition should be assembled and

presented by an

experienced process engineer

who, in addition to the generalknowledge published, would use:



• Personal interaction with the inventors and promoters• Past experience in similar cases• Some reasonable assumptions (which will always be presented as such)• More specific considerations, which are detailed below

The written preliminary process definition document also will include:

• Results from a comprehensive literature survey describing what isgenerally known in this particular field

• Division of the process into defined sections and interconnectingstreams, as shown on a block diagram

• Calculation of the first process material and heat balances (the so-called “revision 0”)

• Definition of at least one feasible implementation scheme• Projection of an industrial implementation framework and timetable• A detailed list of critical feasibility tests

5.1.2 Comprehensive literature survey

The inventors and the promoters have probably already done the best liter-ature survey they could with the means available to them on the core aspectsof their proposal. Now that the field of interest has been both enlarged andmore focused with the participation of additional experienced professionals,a renewed literature survey can be commissioned, in parallel to the otherwork described below (see also Chapter 3, Section 3.6.1).

This publication’s search can be subcontracted nowadays to specialistsor to academic libraries where it is done by computer screening of largedatabases, according to agreed “key-words.” The first result of such screen-ing is generally a very long list of items, including titles, authors, journal,date of issue, language, and possibly a couple of lines of abstract. A firstmanual selection has to be made from the computer’s output, according tosome criteria to be agreed upon. However, the ordering and collection ofworkable copies of the selected publications (and their translation, if needed)could be sometimes lengthy and expensive.

The senior process team should devote a

continuous

effort to supervisingsuch screening and to the study of these copies/references as they arrive,looking in particular for any factual information, and for any possible numer-ical correlation of the included relevant experimental data. In addition, suchanalysis may give some interesting hints about the reasons for any previousresearch work on this subject and about their potential projection on theindustrial scale up to now.

The continuous recording and distribution of the results and the analysisfrom this survey to the core team and to the relevant consultants had oftenprovoked important

practical responses and proposals

concerning the work athand. In the end, all such findings have to be summarized and included inthe material submitted to the second review.



5.1.3 Block diagram

The overall process will be separated, as far as possible, into

different sections

and represented in a

block diagram

with

numbered interconnecting process streams

.This division is very important for all the following work and, therefore, itneeds to be carefully devised so that each block ( = section of the whole process)would contain, as far as possible,

only one well-defined operation

.In this context, a

section

is a definite part of the process in which the flowrates and compositions of the exiting streams are determined uniquely by:

• Flow rates and composition of the entering streams• Operating conditions that can be controlled by the operator, such

as temperature, pressure, residence time, velocities, reflux ratio, andthe like

The presence of recycle (reflux) streams between certain sections and theexact location of their return point are very important aspects in manyprocesses. The two typical examples given below have been chosen in ordernot to trespass into any actual process or new technology handled by anoperating company.

First Example

— A typical illustration of a block-diagram is given inFigure 5.1 as an example describing a new process, which was not completelydeveloped, for producing diammonium phosphate (DAP) from phosphaterock, HCl solution, phosphoric acid, and ammonia following a patentedsolvent extraction process.

21

However, this proposed process also incorporates a

new process concept

,which is hereby offered to the consideration of the readers, as it may haveapplications in many other fields. Instead of an organic solvent cycle circu-lating inside the plant, there is an

internal cycle of ferric ions

(in various forms)kept inside. In short, the incoming HCl solution (stream 1) encounters aferric hydroxide cake (stream 2, with some solid impurities originating fromthe phosphate ore) and dissolves it, giving a FeCl

3

solution. The solid impu-rities are taken out and the hot FeCl

3

with some HCl excess (stream 3) isused to dissolve phosphate ore (4). FePO

4

is precipitated and separated (6)from the resulting CaCl

2

solution (5). The washed FePO

4

cake is dissolvedin WPA (7) — “wet” phosphoric acid — as a mixture of soluble mono- anddiferric phosphate (8). Ammonia (9) is added to that mixture and to a motherliquor DAP recycle (10); more DAP is formed and ferric hydroxide is pre-cipitated. The later is filtered and recycled, the DAP solution (11) is cooledand crystallized, and the DAP crystals are separated and dried (12).

In total, half of the phosphoric acid in the final product originated fromthe reaction of HCl with phosphate rock. The ferric ions are acting as aseparation tool between phosphoric acid and the resulting CaCl

2

and otherimpurities,

including most of the impurities from the WPA,

which precipitatedin the higher pH section. This proposal is also illustrated as an example ofa “black box” in Chapter 10, Section 10.4.3 and Figure 10.3.



Second Example —

This example of a process block diagram (Figure 5.2)is the Gorin-Mizrahi patented process

8

for the recovery of zirconium fromthe natural zircon mineral. (See Chapter 1, Section 1.4. A more detaileddiscussion of the process choices and issues in the high-temperature sectionscan be found in Chapter 6, Section 6.4.4 and in Figure 6.9.)

A commercial grade of zircon heavy sand is finely ground and mixedwith a concentrated solution of CaCl

2

, granulated and dried at 180 to 300

°

C.The process flow sheet of that section is illustrated in Figure 7.5, Chapter7. In these free-flowing aggregates, the CaCl

2

, with up to 6% water, isdistributed in intimate contact with the solid surfaces. The granules areheated and calcined successively in two rotating kilns in series, at differenttemperatures, in direct contact with combustion gases. In the first kiln, thecalcium chloride melts at 782

°

C, reacts with the zircon solids and with thewater vapor, and decomposes, giving very active CaO while releasing HClinto the exit gas stream.

This HCl is then absorbed adiabatically to give an HCl aqueoussolution while scrubbing the exit gases. The overall reaction is completedin the second kiln at 1400

°

C. The reacted clinker is quenched in waterand ground, then partially attacked with the recycled HCl solution. Thecalcium silicate and other impurities are dissolved in the waste solutionand only zirconium oxide remains in the solid phase, which is filtered,

Figure 5.1

Process block diagram for a DAP process.

FePO4 separation

FePO4dissolution

centrifuge

cooling-crystallyzer

solid /liquid

separation

DAPReactor

Phosphateleaching

wastesolids

separation

Hydroxidedissolution

HCl solutioninsol. waste

phosphate

CaCl2 brine

FePO4 cake

Phosphoric acid

Ammonia

ferrichydroxide

cake

DAP filtrate

1

2

3

4

5

6

7

8

9

10

11

12

DAP crystals

mother-liquor

filtrate slurry



completely washed, and dried. The basic technology of all these opera-tions is more or less conventional, and the novelty of the process residesin the exact conditions in the calcination, which give a

liquid–solid reactingfront

and an

intermediate double salt

of calcium silicate and calcium zir-conate. More details on the high-temperature chemistry are discussed inChapter 6.

5.1.4 Quantitative definitions of the different sections

For

each section

, the quantitative definition should consist of two parts,which have to be detailed in the textual description and presented togetherwith the block diagram, in addition to the available data or the “agreedassumptions.”

• Formal

characterization

of the prevailing mechanisms in the generallyaccepted terminology (and in more detail if there is any doubt)

•

Quantification

of the aims to be achieved

This

physical-chemical

mechanism can be, for example:

• A chemical reaction

11–16

• A heat/mass transfer operation

17,19

• A separation operation (see Chapter 6, References 1 to 9)• It also can be a conventional material handling or a storage operation

Figure 5.2

Process block diagram for a zirconium process.

slurry mixing andgranulation

granulesdrying

second kiln

leaching andfiltration

adiabaticabsorption

ground zircon CaCl2 solution

water

fluegases

wash water

HClmakeup

productdrying

waste stream

first kiln

hotgases

hotgases

HCl solution

quenching andgrinding



For example, such mechanisms can be defined as:

• Homogeneous (one-phase) mixing and equilibration of certainstreams

• Neutralization reaction resulting from mixing and reacting differentphases

• Multiple-stages, countercurrent, liquid–liquid extraction battery,which involves

in every stage

the mixing of liquid streams in order toachieve mass transfer of specific components and approach to equi-librium, followed by the separation of the resulting liquids

• Similar batteries for different process functions, such as “extractwash” or “back extraction” in solvent extraction

• Concentration of a solution by evaporation and the subsequent cool-ing of the resulting solution and of the evaporated condensate

• Filtration and washing of crystals on a wedge-wire screen centrifuge• Drying of the solids from a wet filter or centrifuge cake• Separation of a solids stream into (different, defined) size frac-

tions, etc.

The

aims to be achieved in each separate section

also should be given

quan-titative indexes

, such as the minimum concentration, the specification in theexiting stream, the acceptable upper energy consumption, the minimumrecovery of a valuable component, an acceptable waste composition fordisposal, and so forth.

5.1.5 Process calculations for the preliminary process definition

The chemical engineering calculations can follow well-established proce-dures, which are listed and detailed in some of the basic reference books.

6–12

As far as possible, these calculations will be done

in parallel

and will include:The

correlation and analysis

of all the relevant data already available,either from the previous work of the inventors/promoters, of the processengineer, or from previous publications on related subjects, which may havebeen obtained from an extensive literature search (see Section 5.1.2). Thesecorrelation formulas can be

carefully extended

by extrapolation, if needed, aslong as this is clearly recorded as a provisional mean.

The formulation of the

quantitative relations

(known or assumed) that canaffect the process mechanism for each separate section (e.g., the yield ofreaction, the solubility). These relations sometimes can be based on thetheoretical thermodynamics or the physical chemistry knowledge, as givenin basic reference books.

18,19

But it is seldom that in the first stages of adevelopment effort, these sources could be useful or justifiable. Therefore,quite often at this stage, some of these assumptions have to be based on

known analogies with other processes

from the process engineer’s own back-ground (although he may have to keep some of these references secret, andpersonal trust will be essential).



The

evaluation

of the effect that each of the different operating variablesmay have (for instance) on distribution, solubility, recovery, heat effects, andtheir combinations … for each separate section, on the basis of the abovequantitative relations.

The preparation of computer spreadsheets for

each separate section

with the preliminary design material balance and with the heat balance(if the heat effects are important in such sections, which is not alwaysthe case), on a reasonable arbitrary basis, e.g., 1000 units of the main rawmaterial. These balances are prepared by conventional chemical engineer-ing calculations, and this task should give the process engineer a

goodinsight

into the importance of each of the different factors in the

play-of-forces

inside such process (

leverage

). Of course, there are interactionsbetween the different spreadsheets, since each section starts whereanother ends. These spreadsheets can be easily converted at a later stageto any other basis needed.

A list is also prepared of the

critical feasibility tests

that should be doneto define or confirm

some

of the

high-leverage assumptions

taken in thesecalculations before these are presented for the review (see Section 5.3).

5.1.6 Presentation of one feasible implementation formula

This description is, in fact, a

concrete, possibly optimistic

,

illustration

of theimplementation of the concept,

if it could be made to work as intended

. Thestarting point is the

integration

of the above

quantitative assumptions

into one

possible

implementation case, describing an operating plant with the speci-fications of the raw materials and the products, the material and heat bal-ances, the process control, the recoveries, the disposal or treatment of theresulting waste streams, the relevant safety aspects, the choice of materialsof construction for the contact equipment, and so on. Typically, if one of theraw materials have to be transported in large lots, the material handlingfacilities and storage can be significant.

For example, it may be projected that the new process would need largeheat exchangers made from expensive materials (graphite, glass-lined, tan-talum), or that the rapid scaling of such heat exchangers should be expected,considering the composition of the solutions being heated. In such case, onedesign option could be to resort to the technology of organic “heat carrier”(stable liquid or vapor hydrocarbons) and, if this is considered a practicaldesign possibility, it should be studied, defined, and included in the exper-imental program (see Chapter 6, Section 6.2.1)

5.1.7 Possible industrial implementation framework

A projection of one possible industrial implementation framework (

known

or

assumed

) is presented for the proposed novel process with its specificfeatures, such as the possible site, the scale of production, the equipmentsize and function, the different raw materials available, existing connections



to critical services, any possible synergetic coproduction. Such projectionshould help

specify the technological factors which will have to be solved

.For example, the maximum

supply temperature of the cooling water

thatcould be reliably procured or produced in this site depends on the recordedclimatic conditions. It often has been found in warm countries that suchtemperature can have a

critical

importance for the design of a new processbased on evaporation or distillation

under vacuum

, or involving materialswith

low

boiling points

. If the normal cooling water at this site isn’t coldenough, the cost of supplying

artificially chilled

water would have to beincluded or the process scheme radically changed.

5.1.8 Timetable

A reasonable projected timetable for the whole development and implemen-tation project prior to the plant’s start-up and to the market penetration isalso essential to the decision-making forum, in order to:

• Evaluate the availability of the required resources• Coordinate the assistance of the many different support groups and

experts• Connect with the market projection studies

5.1.9 Important note

Obviously, in the beginning, the above

preliminary

“process working defini-tion” would have to be based, in a large part, on weighted and explicit

assumptions

and on

previous professional experience

.Its purpose is to focus the team’s attention as well as to plan any future

work on the

limited scope of application that is of interest in real life

, and to allowfor a more effective allocation of the available industrial R&D resources.

It is agreed that this process working definition will be progressivelychanged, enlarged, and refined in

future numbered revisions

, as more informationwill be gathered and analyzed, and more promising avenues will be defined.

However, such a

working method

has not always been accepted by all. Inmany cases, it has been resisted and even ridiculed by senior scientists, whowere used to the open-ended academic research approach, claiming, “Whatdo we really know for sure? Let’s collect some data first and then we willsee what kind of process will result.”

Bluntly speaking, their

noncommittal

approach represents the

more seriousdanger

to the development of

any

novel chemical process (like gamblingwithout knowing the odds). The least damage can be that a large part of theexperimental data collected would be

outside the scope that is relevant

forimplementation, resulting in a loss of time, resources, and good will. Moreserious damage could be caused if wasting of time and repeated abortivetrials would erode the corporate management’s interest and promising ideaswould be lost.



5.2 Critical and systematic review of the process definition

5.2.1 Review forum

This

second critical review

aimed at reaching operative decisions with regardto the next steps (“no or maybe”) is generally called in by the decision-makerwho can be, for instance, the managing director of the R&D organization,the corporate vice president for new business, or the director of the fundingcommittee, and comparable in function or in title.

This discussion is conducted in a larger forum with ranking colleaguesof the inventors/promoters (“peers”) and with outside experts who areinvited, if and as needed. It should cover all the essential elements, such asthe technology and patents, the corporate strategy and markets, the profitpotential, and the capability to handle the proposed development programwith the resources available.

In a larger organization, there can often be a competition for the priorityin allocations between different projects. The raising and discussion of themore “difficult” subjects in such a review can sometimes be unpleasant, ifit is seen as a personal criticism among working colleagues with complexhuman relations. Therefore, it can be useful to appoint a merciless “devil’sadvocate” to present the pros and cons of the problematic aspects, in advanceand in writing. His contribution would then avoid wasting time in rhetoricand personal maneuvers.

As a result of the first part of this review, a number of specific activitiesshould be approved for immediate execution, and an additional meeting ofthe critical review forum generally would be reconvened by the “decision-maker” a few months later. This additional meeting will then study andreview the different reports prepared on the

feasibility tests

, the

patent discus-sions

, and the clarification of the

critical economic factors

.

5.2.2 Fundamental process issues

In this review, all the fundamental process issues should be raised andfocused on, and a list prepared all information requested to arrive at thefinal clarification of these issues in the future.

• Any apparent reason why “this cannot work?” Have we forgottenanything?

• Could any “wishful thinking” bias be included in the conceptualreasoning?

• Does any quantitative factor have a leverage large enough that mightturn the balance critically away in the wrong direction?

• How to deal with any relevant existing patent claim (see below).• Is the process flexibility sufficient to accommodate some changes that

could be needed to bypass such typical claims, should they appearin the future?

• Is there a sufficient profitability potential (see below)?



As a result of this review, a list of

critical tests for process feasibility

shouldbe defined and agreed upon (see Section 5.3).

5.2.3 Patent situation

Relevant

patent claims granted to another party, which may have been foundin the first survey, will be discussed in this review. In many cases, suchprevious claims may still be avoided quite fairly, on the basis of their exactformal definition, but such constrain can dictate some changes in the devel-opment program.

Unfortunately, patent applications are not made public for 2 to 3 yearsafter their filing and many inventors are using perfectly legal tactics todelay their publication, so one also may have to look for

hints

fromprofessional circuits and to prepare for eventual “surprises” from thisdirection.

The promoters will also draw up and present to this forum a verydetailed list of

every possible patentable claim

for the new process. After thisreview and the approval to proceed farther, this list will be used for addi-tional discussions with the patent attorneys and the specialists, and after anelimination and selection procedure, for the drafting of a comprehensivepatent application (see Chapter 8).

Note that all the formal procedures of patenting are now quite rigid andvery few procedural decisions are really needed, apart, of course, from the

delicate issue of the names listed as the inventors. In particular, since theestablishment of the PCT (Patent Cooperation Treaty), all international appli-cations can be based on the examination done in one patent office (i.e., inWashington, D.C.).

Therefore, the main deliberations with the patent attorneys on any newpatent and the resulting decisions will be related to the exact formulationand wording of the claims in the application. Even among patent attorneys,there is a certain degree of specialization, since only a professional with areal knowledge of the particular scientific technological field can contributeeffectively to such formulation.

However, in some corporations, any talk about a patent applicationwould immediately involve their top lawyers (who usually are very busy)and, therefore, the patenting procedure could become very slow and veryexpensive without any real additional contribution. This frustrating situationis often a pitfall.

As a curiosity, in the U.S., a corporation is legally bound to pay theinventors cash in return for their assignment of the patent rights, even if theinventors are their own employees or their regular consultants under con-tract. This cash payment is often done in the form of a brand new $1 bill,which is handed over to each inventor with his signature, and which is oftenframed together with the invention certificate.



5.2.4 Profit potential

It also should be shown and agreed in this review that the profit potential ofthe proposed process could be attractive enough to justify the estimated costsof the next stages of a development program.

There can be many different definitions of the profit potential, which areused by different corporations and industrial sectors in various countriesand tax situations. In general, this profit potential should quantify the expectedincrease in ROI (Return On Investment) above what would be the ROI foran available, safe, no-risk investment, over a 10-year period.

The profit potential, as an absolute number for a particular proposal(i.e., in dollars per year) is obviously getting higher as the contemplatedscale of production or the sales turnover are higher, while the costs of theprocess development (the risk?) are much less affected by the size, if at all.Thus, a new process could be brilliant and sophisticated, but if its finalproduct has only a small market potential, the straight prospects of approv-ing funds for its development will be dim. Such a proposal then will begenerally presented as a strategic investment, opening the way to … (asthe popular joke says, “One can save more money by running behind a taxithan by running behind a bus).

At this early stage, the standard economic calculations can only berudimental and based on reasonable assumptions. The bottom-line resultswill generally not be clear-cut either way, but they will indicate mostlyorders of magnitude (so-called “back of an envelope” calculation type). Thedebatable issues should focus on the degree of confidence that can beattributed to some high-leverage factors, e.g., sale prices, cost of certain rawmaterials, possibly transportation, taxes and customs duties ofexport/import, commissions, royalties, etc. As a result of this review, afact-finding program will be defined to confirm or correct the requiredquantitative assumptions for such critical economic factors, in addition tothe publicly available information.

According to their specific strategic considerations, most corporationswould be ready to “gamble” a certain percentage (say between 1 and 20%)of the yearly profit potential on the net costs of a comprehensive develop-ment program. Obviously, such a budget would only be released progres-sively, in installments, as certain objectives are achieved with positive results.

5.3 Design and execution of the feasibility tests5.3.1 Purposes of the feasibility tests

Feasibility tests should convince the decision-makers and demonstrate thatthe results from the new aspects can be achieved more or less as expectedin each stage of the process in order to justify a more extensive experi-mental program.



As for the “more or less” qualification in this context, it is generallyagreed that the better results cannot be obtained in the first attempts, butshould be achieved more likely in the more favorable conditions that will bedefined later, after an extensive process optimization.

It is also realized that such demonstrations can generally be attemptedonly with severe limiting conditions, such as:

• Small, bench-scale, batch tests• Standard or improvised laboratory equipment and analytical facilities• While starting with synthetic “clean” mixtures and reactants “from

the bottle”

The results from each stage can either be shown by the direct analysisof the phases obtained after the test or calculated indirectly on the basis ofthose analyses by accepted chemical engineering methods.

For example, a wet filter cake can contain some impurities, which aredissolved into the layer of liquid that is retained on the solids. This layercan be washed out almost completely on a conventional industrial filter, buta similar washing operation cannot be done conveniently on a small-scalelaboratory batch filter with the same results. In this case, the level of theseimpurities related to the retained filtrate can be calculated on the basis ofthe retained water (or of another soluble component) and then deduced fromthe level found in the unwashed filter cake.

5.3.2 Equilibrium conditions

In the limiting experimental conditions mentioned above, a more convenientfeasibility demonstration can be achieved for those process operations that arebased on equilibrium conditions.

For instance, a particular vapor–liquid equilibrium system can be gov-erning some distillation, rectification, or stripping operations in the proposednovel process. A reliable calculation of the results from these operationscan be obtained on the basis of the correlation of the composition of thevapor phase with respect to that of the liquid phase at equilibrium. Thetheoretical background for the calculations is well established and severalcorrelation formulas were published on the subject. A limited number ofexperimental points on the particular system under consideration can beinterpolated quite safely and used for such process calculations. All such“points” connect the two compositions of the phases at equilibrium inspecific external conditions of temperature, pressure, and the partial pres-sure of inert gases present.

Similarly, a liquid–liquid equilibrium system can be relevant to a proposedsolvent extraction process. The composition of the two liquid phases, foundin a specific equilibrium test in certain defined conditions, can be translatedinto a distribution coefficient for each of the components of interest. Thecorrelation of this distribution coefficient with the operating conditions can



be used for calculation of a multiple-stage countercurrent process, in whichthe two exit liquid phases from every stage are assumed to be at equilibrium.

Solids–liquid equilibrium data can regulate certain dissolution and precip-itation processes, which are widely used in the inorganic salts industriesand mineral treatments, and also in the production of organic crystals. Inall of these processes, the determination of the quantitative relations forthe solubility at equilibrium, in several conditions in the projected range,can be sufficient, at least for the preliminary process design and feasibilitydemonstration.

5.3.3 Scale up of reactors

The scale up of batch reactions in mixed vessels is well established in chemicalengineering using the reaction kinetic curves and the definition of the mixingregimes. Continuous mixed reactors can also be designed reasonably wellfrom small-scale batch tests, or upscaled from small continuous mixed reac-tors, using correction factors. Thus, the feasibility demonstration of suchreactions can be based on straightforward batch reaction tests.

Similarly, the mixing and the reaction between gases flowing in a pipereactor are also relatively easy conditions for the process feasibility demon-stration on a quite small scale, and for reliable scale up based on hydrody-namics conditions and residence time.

5.3.4 Physical separation operations

The scale up of solid–liquid separation equipment has been well estab-lished.21 Many continuous separation operations (solids from liquid or liquidfrom liquid) can be demonstrated, sized, and upscaled quite well from batchtests made in standardized conditions. In this context, the term “standard-ized conditions" involves the definition of a particular set of conditions whichare recommended for a batch test in order to obtain applicable results.

For example, the separation obtained in an industrial decanter or thick-ener — from a “feed” suspension into a more concentrated “underflow”slurry and a clear liquid “overflow” — can be demonstrated and quantifiedfrom a standardized settling test in a 1-liter glass cylinder starting from awell-homogenous slurry (in a thermostatic bath, if necessary). The settlingcurve of the upper limit of the concentrated slurry obtained from each test(see typical example in Figure 5.3) depends on the initial solid concentration,on the differences in density between the solids and the liquid, on the liquidviscosity, and on the degree of flocculation.

The plotting of an empirical settling curve allows the calculation of themaximum solid concentration in the underflow, the level of entrained fines inthe overflow (if any), and the horizontal area of the settler needed, per ton-hour of solids, by the well-established Kinch method following Coe-Clavenger(see p. 4.121 in Chapter 6, Reference 1). This experimental procedure is usedalso for studying the effects of the addition and dozing of flocculating agents.



Similarly, the separation of a cake of solids (including the washing ofthe cake) from a particular slurry in a filter or in a centrifuge can be dem-onstrated and quantified on a small scale with the same type of results.Note, however, that a continuous filter is, in fact, a batch filter that happensto be moving on a belt during the filtration cycle. The difference obtainedin the rate of filtration derives from the operating variables: the pressuredifferential on the filter or the G-forces in the centrifuge, and the hydraulicresistance of the formed cake. Flocculation, however, does not affect sig-nificantly these operations.

5.3.5 Scale-dependant and dynamic flow operations

In contrast with the operations discussed in the above three sections, a feasi-bility demonstration cannot be readily performed for such operations in whichthe results are scale-dependant, such as, for instance, the crystal size distributionobtained in a continuous crystallization (see Chapter 6, Section 6.4).

The feasibility demonstration also cannot be readily performed if themechanisms are based on dynamic flow conditions concerning mostly separa-tions between phases (see Chapter 6, Section 6.3) In such cases, any feasibilitydemonstration has to be connected to a particular equipment choice, and somespecific form of piloting is necessary to determine the dimensions and results.

Figure 5.3 Slurry settling curve — Kinch procedure.

time

final

initial

height

settling curve ofsolids front

point of mostrapid change of

slope

Tx



A shortcut sometimes can be found if a logical analogy can be establishedto another known process, which is in actual operation and accessible to theR&D team or their consultants. Then, if it can be established that the newproposed process and the operating process behave more or less similarlyin simple bench-scale tests, this analogy could justify further piloting.

For example, the feasibility demonstration of many proposed wastestream treatments, based on dynamic flow conditions, is very problematic,but these treatments generally fall in a small number of categories.

5.3.6 Extreme conditions

It is not a simple proposition to improvise on laboratory bench-scale afeasibility demonstration for a process operation which has to be done inextreme conditions of temperature, pressure, electrical fields, etc. If such anextreme operation is an essential element in the new process, small testingequipment could probably be specially designed and operated, but thiswould be expensive, require a long time and expertise, and would divertthe team’s attention.

In certain cases, small-scale testing equipment with associated services(and valuable advice) can be rented from one of many suppliers of furnaces,kilns, autoclaves, electrostatic and magnetic separators, plasma torches, etc.These suppliers can also provide experienced engineers to perform thesetests, since they are interested in promoting good will towards their know-how. The main concerns against such services are the unavoidable secrecyleaks and possibly the geographical distances.

If the extreme operation is a self-contained side element in the newprocess, it should be well defined, isolated, and subcontracted to one of thesespecialized suppliers.

5.3.7 Actual raw materials

In certain processes, it can be very important to perform such feasibility testswith the actual raw materials, since a synthetic mixture cannot duplicateexactly the complex phases structure and/or the compositions of these mate-rials in which a large number of impurities can sometimes be involved.

In many actual projects, the use of certain raw materials in later testsdid result in serious nonexpected problems; for example, the precipitation ofsolids causing incrustation on the walls of the equipment and pipes, or atendency to emulsify, or the precipitation of colloid suspensions, or a coloringphenomenon, etc.

In other cases, the reaction kinetics with the actual solid raw materialswas much slower (by orders of magnitude) than the reaction kinetics withthe synthetic mixtures.

If a practical solution to such troubles cannot be provided in time andincluded in the proposed industrial process design, the project will be“killed” sooner or later, at least in its initial form. Therefore, it is important



to discover these problems as early as possible by using representative samplesof the actual raw materials in the feasibility demonstration tests.

Unfortunately, such representative samples cannot always be procuredat the start. This difficult situation was typically encountered when the newprocess involved the treatment of mineral concentrates from new depositsthat, as of yet, have not been fully explored, or the down-stream treatmentof some material that was expected from certain “future” operations.

5.3.8 Analytical difficulties

In some situations, the available analytical laboratory personnel may nothave previous experience with the exact type of analyses required for thesefeasibility tests and they will have to learn, introduce, and calibrate newmethods. This can be a lengthy procedure, and the time needed can possiblybe reduced with outside help. The allocation of priority in this area, or theneed to compromise on a “second-best” method, had often caused delaysand personal tension.

5.4 Analysis of the results from feasibility testsWhen these results become available, it is advisable that the promoting teamprepares and presents two separate reports, which will be studied and dis-cussed in different contexts and review meetings (sometimes again manyyears later).

1. A report on the results of the feasibility tests, which should bepresented in the normal format for R&D experimental reports witha complete description of all the laboratory procedures and equip-ment, all data collected, and, in particular, any observation aboutunusual features.

2. Another report discussing the significance of the experimental resultsand observations from these tests, as regards the process feasibilitydemonstration and the design issues of the proposed novel process.This report may also include further chemical engineering calcula-tions or economic evaluations.

The discussion in this report should also define exactly a limited rangefor each of the variables to be covered in any future experimental programas basis for the process design.

5.5 Second review of the process definitionThe forum of the second critical review is generally reconvened by thedecision-maker along with participating colleagues (“peers”) and the called-in experts to study and review the different reports that were distributed inadvance and in writing. The reports include:



• Feasibility demonstration tests• Patent discussions• Clarification of the critical economic factors

This second review can end up in one of the following ways:

A. In most cases, the analysis and discussion of these reports wouldgive the “green light” for proceeding with the experimental program(see Chapter 6), the preliminary process design (see Chapter 7), and theeconomic analysis (see Chapter 8). If this program is agreed upon, thiswould be the appropriate time to formalize a contract transmittingthe implementation rights from the promoters to the corporation. Thecorporation would then confirm the appointment of a project managerto carry on the responsibility of the future program. This managerhas most probably already been a member of the process evaluationteam up to this point.

B. In other cases, the results and calculations could indicate a need tocorrect or readjust some of the initial process working definitions. Thefile would be given back to the promoters for the repeat of certaintests, additional reports, and back for another similar review.

C. In certain cases, the continuation of the project could not be logicallyjustified in the present framework, and it would be terminated at thispoint, at least until the promoters’ prayers for some surprising de-velopment are granted.


• An essential starting point is a preliminary process definition to bringeverybody concerned to an explicit common reference basis, illustratea concrete venture, outline a proper experimental program and startits detailed design while focusing on the limited scope of applicationthat is of interest in real life, and allowing for a more effective allo-cation of the available industrial R&D resources. This process work-ing definition will be based, in a large part at the beginning, onweighted and explicit assumptions and on previous professional ex-perience, but it will be progressively changed, enlarged, and refined.However, such a working method has often been resisted and evenridiculed by senior scientists who were used to the open-ended ac-ademic research approach.

• A novel process could be brilliant and sophisticated, but if its finalproduct would have only a small market potential, the straight pros-pects of approving funds for its development will be dim. Such aproposal will then be generally presented as a strategic investment,opening the way to new potential products.



• The feasibility tests should convince the decision-makers and dem-onstrate that the results from the novel aspects in each stage of theprocess can be achieved more or less as expected to justify a moreextensive experimental program.

References1. Biegler, L.T., Grossman, I.E., and Westerberg, A.W., Systematic Methods of

Chemical Process Design, Prentice Hall, New York, 1997.2. Douglas, J.M., Conceptual Design of Chemical Processes, McGraw-Hill, New

York, 1988.3. Duncan, T.M. and Reimer, J.A., Chemical Engineering Design and Analysis:

Introduction, Cambridge Press, London, 1999.4. Seider, W.D., Lewin, D.R., and Seader, J.D., Process Design Principles: Synthesis,

Analysis, and Evaluation, John Wiley & Sons, New York, 1999.5. McCabe, W.L., Smith, J.C., and Harriot, P., Unit Operations in Chemical Engi-

neering, 5th ed., McGraw-Hill, New York, 1993.6. Hicks, T.G., Ed., Standard Handbook of Engineering Calculations, Section 6.

Davidson, R.L., Chemical Engineering, McGraw-Hill, New York, 1972.7. Clarke, L. and Davidson, R.L., Manual for Process Engineering Calculations,

McGraw-Hill, New York, 1975.8. Branan, C.R., Rules of Thumb for Chemical Engineers, 2nd ed., Gulf Publishing

Co., 1998.9. Meyers, R.A., Handbook of Petroleum Refining Processes, 2nd ed., McGraw-Hill,

New York, 1996.10. Perry, R.H. et al., Chemical Engineers’ Handbook, various editions, McGraw-

Hill, New York, 1999.11. Froment, G.F. and Bishoff, K.B., Chemical Reactor Analysis and Design, 2nd ed.,

John Wiley & Sons, New York, 1990.12. Smith, J., Chemical Engineering Kinetics, 3rd ed., McGraw-Hill, New York, 1990.13. Schmidt, L.D., The Engineering of Chemical Reactions, Oxford University Press,

Oxford, 1998.14. Fogler, H.S., Elements of Chemical Reaction Engineering, 3rd ed., Prentice Hall,

New York, 1998.15. Levenspiel, O., Chemical Reaction Engineering, 3rd ed., John Wiley & Sons, New

York, 1998.16. Butt, J.B., Reaction Kinetics and Reactor Design, 2nd ed., Marcel Dekker, New

York, 1999.17. Honig, J.M., Thermodynamics Principles Characterizing Physical and Chemical

Processes, 2nd ed., Academic Press, New York, 1990.18. Klotz, I.M. and Rosenberg, R.M., Chemical Thermodynamics: Basic Theory and

Methods, 6th ed., John Wiley & Sons, New York, 2000.19. Coulson, J.M. and Richardson, J.F., Chemical Engineering Fluid Flow, Heat Trans-

fer, and Mass Transfer, different editions, last 6th eds., Butterworth-Heineman,Oxford, 1999.

20. Rohsenow, W.M. et al., Handbook of Heat Transfer, 3rd ed., McGraw-Hill, NewYork, 1997.

21. Purchas, D.B., Ed., Solid/Liquid Separation Equipment Scale Up, Upland Press,Croydon, U.K., 1977.



22. Mizrahi, J., New process producing phosphoric acid from phosphate rockand hydrochloric acid – via ferric phosphate, paper presented at the Int.Solvent Extraction Conference, Barcelona, July 1999. Also Israel Patent120,963, June 1997.



chapter 6

Experimental program

6.1 Basis

6.1.1 Experimental program purposes

Main Purpose —

At this stage of the process development, the main purposeof the experimental program is the collection, the correlation, and the pre-sentation of the

design data

that is specifically needed for the design andoptimization of the new process, as defined and in the

limited range of variablesof practical interest

.It is important to note that the scope of the investigation can depend

also on the

variability

of the particular function under consideration. It canbe found, after the first series of tests, that the already mentioned range ofspecific interest happens to be located in one part of the function wheresharp changes can be seen from a first plotting of all available information.In such case, it is advisable to enlarge the scope of investigation in order toassure a reasonable reliability when interpolating between experimentalpoints. The experimental program, therefore, is formulated in relation to theperceived needs in one particular situation.

Unexpected Problems —

Another important purpose includes the

obser-vations

of possible, but unexpected problems, that can occur and that shouldbe dealt with. These can be, for example, difficulties in the separationbetween phases, slow rates of reaction/mass transfer, colloidal precipitates,unwanted color, etc. (see below). The experimental staff should be instructedto observe carefully and to call their supervisor whenever anything seemsunusual. The “top” R&D managers are often seen circulating between thebenches when such tests are done to obtain a personal “appreciation” of thebehavior of the reacting or separating mixtures.

Preparation —

In addition, the preparation of relatively large represen-tative

samples

of certain products or of certain intermediate phases are oftenneeded for further specialized tests, for market surveys, or just to “showaround” in the promotion contacts for the project. Therefore, generally allthe materials resulting from these tests should be well packaged, labeled,and stored for future use.



6.1.2 Different sections

The separation of the process into the different sections was already rep-resented in the

process “map”

(

block diagram

), with the formal

definition

ofthe prevailing chemical mechanism, of the separation between phases, andof the process results expected in each separate section (see Chapter 5,Section 5.1).

Before starting the experimental program, these definitions should bediscussed systematically,

well understood, and agreed

upon among the inven-tors, the process engineers, and the senior experimental staff. The calcula-tion methods that will be requested for

the process design of each operation

will be formulated and agreed upon by the whole process engineeringteam. For this purpose, use the manuals and textbooks listed as referencesin Chapter 5, as well as for those concerned with the separation processeslisted in this chapter.

7–10

Note that many of the operations in any chemical plant can possibly bedesigned on the basis of

conventional

know-how, with the specific input ofonly a few specific physical properties; for instance, all the sections con-cerned with material handling, liquid flows, blending, packaging, spraying,gas compressing, steamboiler, cooling tower, etc. Thus, the experimentalprogram will not be concerned with such operations at this early stage ofprocess development.

6.1.3 Quantitative data needed for process design

Guided by the definitions, the process engineers also should prepare a listof

all the quantitative data

that will be requested for the process design of eachoperation. Some parts of this design data may be already available in thefiles from the previous analysis of the results of the feasibility tests, from thepromoters’ own sources, or from earlier publications in related fields. Thesystematic organization of what is available will allow the delimitation ofthe missing data that should be generated in the experimental programpresently considered.

Discontinuities are often found between the sets of data obtained fromdifferent sources, as it may be seen when these are plotted on a commongraph, due to the differences in experimental or analytical techniques. There-fore, in this analysis and determination, it is preferable to allow for significantoverlapping to arrive at a reasonably reliable common function.

(

In the author’s considered opinion, there is not much point in designing andstarting any significant experimental program without performing first this processengineering analysis

.)

6.1.4 Format

At the same occasion, it would be useful if the process engineering teamcan specify exactly the preferred format for the results on these data to beused in the experimental reports to allow their direct application in the



process calculations. As there can be many parameters in each stage, the

primary variables

should be indicated in the order used in the calculations(see Section 6.2.1).

This

early

specification

of the format can avoid or reduce the communi-cation problems and the waste of time devoted to clarifications and recal-culations, which often happens between the process engineering team andthe experimental group. In many cases, these two units can also be situatedin geographical locations far apart and may not be able to meet frequentlyface-to-face.

It would also be useful to decide as far in advance as possible thepreferred

order

for the generation and transmittal of

partial data

to theprocess engineering team in

separate, successive, numbered reports

. Thisdemand can appear to be trivial, but this has been, in fact, a sore point inmany projects. If certain parts of the process design work can be startedand advanced before all the data is transmitted in one big bound report,some of the pressure can be relieved from a

serious bottleneck

in processdesign. It generally happens that as soon as the final experimental reportis issued, everybody wants to know all its implications on the new process,the plant under consideration, the economic parameters, etc. On the otherhand, the preparation of serious answers takes time and experienced pro-cess engineers are scarce.

6.1.5 Representative raw materials

As far as possible, these R&D tests should use

representative samples

of theactual raw materials, fuel, water, reagents and additives, filter aid, activecarbon, and IX resins that would be expected to be used in the final plant.As discussed previously, a synthetic mixture of pure laboratory chemicalsfrom the bottles on the shelf cannot duplicate in many cases the exactcomplex physical structure and/or the large number of impurities in theseraw materials. Similarly, whenever it is intended to use combustion gasesin direct contact with the process streams (e.g., in a calciner or a dryer),the exact composition of the fuel can be significant. Such combustion gasescan contain

ash particles

or

gaseous impurities

that can contaminate theproducts or would need to be treated in the waste streams or can accumu-late in the plant.

It has often been found in real cases that the use of

certain raw materials

in such tests did result in

serious, nonexpected problems

. For example, insolvent extraction processes, some impurities can precipitate as fine solidscausing the liquid–liquid mixture to emulsify and, thus, preventing thenormal operation of the process. In one particular case, the raw materialcontained an impurity with oxidizing power, which attacked anddestroyed the organic extracting reagent used. In hydrometallurgy andsalt processes, the precipitation of solids that stick or build on the wallsof the equipment and pipes can stop a plant. Some natural streams can,when heated, release some dissolved noncondensable gases, which may



disturb the vapor–liquid equilibrium, and/or (at least) need to be collectedand vented properly. Other problems can be the precipitation of colloidsuspensions, coloring phenomena, etc. Such troubles may be seriousenough to “kill” sooner or later the proposed industrial process at leastin its original form, so it is very important to discover and diagnose themas early as possible. Possible solutions can include pretreatments or evenchanging the source of the problematic raw material.

Unfortunately, it often happens that, despite all reasonable efforts, rep-resentative samples of all the actual raw materials cannot always be readilyprocured from the beginning of the experimental program.

First Situation —

This difficult situation has been typically found, forinstance, when a new mineral deposit was being explored and small samplesof the expected raw materials can only be separated and reconstituted fromsmall drilling rig cores in quantities hardly enough for the analytical andpreliminary bench tests.

Second Situation —

Another typical case has been the development anddemonstration of a proposed process, which was intended to handle aneffluent stream expected from a “future” operation that was still at the designor construction stage.

Third Situation —

This situation has been also encountered now andagain in the development of large-scale biotechnology processes, which typ-ically consist of two separate parts:

1. The

fermentation

section, which is producing a broth containing avaluable product (e.g., a carboxylic acid)

2. The

recovery

section, intended for the separation of such valuableproduct from the broth into a pure, concentrated, marketable form

These two sections are generally developed and even designed sepa-rately by two specialized groups, and they are often built in different plots“across the road.” Obviously, all the characteristics of the new recoveryprocess are derived from the exact composition of the

expected fermentationbroth

, as defined at the time of the project justification. But it often happenedthat while the “recovery” group was developing, designing, and buildingtheir processing unit, the “fermentation” group was continuing their effortsto improve their part. They would aim at a better

productivity

(which is theaverage production

rate per unit volume

of fermentor) and/or a better yieldon the raw materials. This can be quite natural from their point of view,but the resulting changes in the broth composition (mostly with regard tothe associated impurities) can have serious (negative) effects on the recov-ery process, as developed.

A mutual

understanding and coordination

between these two groupsshould be obvious, but often can be delicate in real life and may have to beimposed from above. To be fair, the fermentation group is not alwaysinformed of the downstream development (“What do these biologists knowabout our separation processes?”). But, at least in one case known to the



author, when the fermentation group was informed that one of the impuritiesgenerated by the microorganism constituted a very serious separation prob-lem, they found a genetic “trick” to prevent this particular impurity andreplace it with a less problematic one.

In such cases, where

representative samples

of the actual raw materialscannot always be readily procured from the beginning, an experimental pro-gram on “synthetic” mixtures can only be done as an

exploratory work

aimedat the

preliminary

process design. The results need to be clearly marked assuch, and this situation reflected in the safety factors included in the economicanalysis.

Repeated tests

should be scheduled for later, in the exact selectedconditions, as soon as the actual representative samples can be obtained.

6.1.6 Classification of missing data

The data missing at the beginning of the experimental program can bedivided into three main categories according to the testing techniques thatwill be required in obtaining the results, as discussed below, and the designmethods for:

• Operations based on

chemical equilibrium

data, (as reviewed in thecomprehensive book by Henley and Seader

2

• Operations based on

dynamic flow conditions

• Operations that are

scale-dependant

, i.e., the results depend on the

absolute size

of such equipment

6.2 Chemical equilibrium data

(See basic reference books on separation processes and, in particular, oneson the equilibrium stages, which are the most useful tools in new processdevelopment.

1–7

)

6.2.1 Vapor–liquid equilibrium system

Vapor–liquid

(reversible) equilibrium systems are used in unit operations,such as distillation, rectification and stripping, evaporation, and condensa-tion. (Note that

gas–liquid

equilibrium systems, which are relevant in unitoperations dealing with scrubbing, cooling, etc. of a gaseous stream, havesome similarity. However, these will be discussed separately, in the nextsection.) Data needed for process design are obtained by correlating the

compositions of both phases

at equilibrium in certain conditions of temperature,absolute total pressure, and the partial pressure of noncondensable gases(inert, nonreactive) that may be present (assuming that such partial pressuredoes not exceed 70 to 80% of the total).

The pair of

compositions for both phases

can be obtained from a

total reflux

test, where the vapors from a boiling liquid phase are totally condensed atthe same absolute pressure and all the condensed liquid is returned to the



boiling liquid. As equilibrium is established, samples are withdrawn fromboth the boiling liquid and the refluxed condensed liquid, and completelyanalyzed for all components. If there are

only two

components, the plottingof the results is straightforward.

But since, in most cases, there are

more than two components

present ineach phase, one has to decide from the start

which two components are thevariables under study

and which other components are to be considered asparameters for the purpose of the present process design, together withthe obvious physical

parameters

, such as the temperature, absolute pres-sure, and partial pressure of noncondensable gases. All the parametershave to be kept constant in each series of tests, to obtain a

cross section fortwo variables

.One may see that the experimental program for a typical system with

four to six components can become very complex unless one limits from thebeginning the

ranges of practical interest

(see Chapter 5, Section 5.1). Once thischosen range is covered with a limited number of experimental “points,”the numerical results can be interpolated quite safely into a mathematicalfunction by using one of the published theoretical correlation formulas. Thecorrelated function then can be used for the process calculations of the

multiple stages

equilibrium system in one of its forms: countercurrent, cocur-rent, or crosscurrent.

The process design can be done using the “theoretical stages” concept,and then translated into an equipment design, by relying on the correlationlinking the “height of theoretical unit” with the operating conditions andthe details of the chosen equipment. Such correlation has been published forseveral basic designs or may be obtained from the suppliers of more spe-cialized equipment.

When there are many condensable components from the beginning (asin petroleum processing, as an extreme case), one may have to “cut” themixed feed by a coarse separation into two or three ranges (“heavies” or“lights”) and to treat

each range as a separate problem

with recycles at thestarting point.

A special case is the concentration of a solution containing nonvolatilesolutes by evaporation of water (or another solvent), leaving the nonvolatilesolutes in the concentrated solution. The vapor phase contains only onecomponent, but the concentrations of the solutes into the liquid phaseincrease gradually, decreasing the partial pressure of the water. In such case,the important data are the quantitative link between the absolute pressureand the boiling temperature of the solution and the concentrations of thesolutes below their saturation limit. These data are essential, for example,for starting the design of energy-efficient,

multiple-effect

evaporators, whichare a critical element in many processes (e.g., salts and sugars).

An equally important result of such tests can be any

observation

aboutthe precipitation of certain solids from the liquid, and the form and behav-ior of such solids, in particular as to their incrustation inside equipmentand pipes, or on heat exchangers surfaces (for their composition, see



Section 6.2.3); as well as the conditions of the release of any noncondens-able gases dissolved in the feed solution.

Another important field of process development is concerned with theseparation between two volatile components that cannot be obtained directlydue to the presence of an azeotrope or another particular feature of theequilibrium curve. (As a reminder, at the azeotropic point, the compositionsof the liquid and of the vapors are identical.)

A well-known case is the system HCl-water (already mentioned inChapter 4, Section 4.3.2) which is dominated by an azeotrope at 20 to22% HCl (the exact number depends on the absolute pressure). Every tonof HCl generated “below the azeotrope” is accompanied by at least 4 to5 tons of water at its maximum practical concentration and this featuremay prevent or limit its use in other processes. “Breaking the azeotrope”means obtaining a more concentrated solution that can be handled atambient temperature (say about 30 to 40% HCl) or even a 100% dry HClgas, if needed.

Such a result is possible by using a cycle of CaCl

2

brine in a close cycle,as the brine absorbs the water and releases the HCl, but this is a compli-cated process with many reflux streams. It is also an expensive process,both in the investment in the HCl-resistant equipment and in the energyconsumption. Another commonly found complication can be the presenceof nonvolatile components in the starting HCl solution, which can accu-mulate in the circulating brine. In such case, the starting solution shouldbe completely evaporated upstream and the heat loads should be redis-tributed. This problem was at the time an open field for creative processdesign, aiming at a better use of the energy and the expensive heat exchang-ers, and of any possible synergetic utilization of sources of low-temperaturewaste heat.

11–14

Different aqueous solutions were used, including MgCl

2

and LiCl. It was also proposed to replace the expensive heat exchangersby direct contact heating with organic “heat carriers.” (See below and alsoChapter 5, Section 5.1.5.)

Direct contact heating technology, with organic “heat carriers” (stable hydro-carbons, liquid, or vapors)

— Certain processes need large heat exchangersmade from expensive materials (resistant to corrosion, such as graphite,glass-lined, tantalum) to introduce heat into the process streams and evap-orate certain components, and similarly for removing heat in condensers. Inother cases, heating of such solutions in a regular heat exchanger wouldprecipitate solids and cause the rapid scaling of such heat exchangers.

One can resort to introducing very hot organic liquid or vapor “heat-carrier” in direct contact with the process stream to be heated. After heattransfer and equilibration, the organic liquid is separated, removed, washed,and reheated in a separate boiler made of cheaper materials. Although theheat carrier material would have a boiling point much higher than any ofthe components present, it can have a definite vapor pressure in the hotterparts of the equipment, which should be taken into account and includedin the experimental program.



6.2.2 Gas–liquid equilibrium system

Gas–liquid (reversible) equilibrium systems are relevant in unit operationsdealing with cleaning or cooling of a gaseous stream in contact with a liquidphase. In such operations, the concentrations of certain components thatexist in both the liquid and the gas phase are related by a definite reversibleequilibrium function, for a definite set of parameters.

For example, water and ammonia can be both in a gas stream and in anaqueous solution (or water and HCl, or water and methanol, and the like).The ammonia can be recovered from the gas stream into an aqueous solutionin a packed column where the gas stream (say with a few percents of ammo-nia) will be introduced from the bottom and will flow upwards (exiting with,say, 0.02% ammonia), while water is introduced at the top and flows down-wards, countercurrently. The liquid also may contain nonvolatile solute com-ponents, and the greater part of the gas stream would consist of “inert”noncondensable gases.

In principle, such a system can be studied as a vapor–liquid equilib-rium system, and a certain number of theoretical equilibrium stages canbe defined to obtain a certain result. But there is a

quantitative difference

compared to a regular vapor–liquid equilibrium system. The

kinetics ofreaching such an equilibrium

are much slower, as they depend on the dif-fusion of the relatively few condensable molecules in the bulk of the gasphase until they reach the liquid interface, and possibly also on the “resis-tance” to mass transfer of the layer adjacent to such interface. So, the

contact conditions

are often

more important

than the theoretical equilibriumand the height of a theoretical equilibrium stage must be

determined exper-imentally

for each of the exact sets of operating conditions and for theexact geometry of the packing in the column. It becomes a completelyempirical design and the position of the equilibrium curve has, in fact,little practical importance.

6.2.3 Liquid–liquid equilibrium system

Similarly, a liquid–liquid reversible equilibrium system can govern a solventextraction process, which is intended to separate, concentrate, or purify aparticular component from a mixed solution, such as a fermentation broth,a leaching solution from a mineral acid reaction, or a waste stream fromother operations.

One can refer to the basic reference books

15–18

and note that the “official”denomination is “liquid–liquid extraction,” but most people in the field keepcalling them “solvent extraction processes.”

Generally, one is considering two liquid phases, but there also existsinvariant systems with

three liquid phases

at equilibrium, according to Gibbs’“phases law.” At least one of these systems was used in the IMI “cleaning”process for separation of clean phosphoric acid from wet phosphoric acid(see Chapter 4, Section 4.4.3, Reference 26).



Again, in almost all processes of

practical

importance, there are manycomponents in each phase. One has to define all these components and theirranges of concentration and to choose, on one hand, the

variable of majorinterest

and on the other hand, the ranges of parameters (such as the con-centrations or ratios of the other constituents and the physical conditions)that can be covered in a

reasonable

experimental program. If one is not carefulin his choice, the number of tests required can easily shoot up exponentially.

The “distribution coefficient” of this major variable can be correlatedand used for multiple stage process calculations in the defined ranges ofparameters. The major difference from the vapor–liquid

physical

equilibriumsystems is that in most liquid–liquid extraction processes, the major variableof interest in any particular process can be either an

ionic

or a

molecular

entity,according to the

chemical

extraction mechanism.Once this procedure is well understood, the bench-scale experimental

program for the development of a separation process based on solvent extrac-tion can be relatively straightforward. The technique of the so-called “separa-tion funnels” tests is based on equilibration in defined conditions, samplingand analyses, and it can be carried out routinely by laboratory technicians.This fact of life was probably one of the main reasons for the successfuldevelopment of many dozens of new solvent extraction processes in the years1960 through 1980 in various countries. Very promising R&D programs in thisfield are continuing nowadays inside some of the large industrial corporations,although not much is published about that at international conferences.

In this connection, it is important to stress the experimental techniquecalled “limiting conditions,” which makes it easier to study the effect of onevariable at a time. If, for example, 50 ml of a starting aqueous solution aremixed with 50 ml of a solvent phase, the concentrations of the componentof interest after equilibration will probably change significantly in bothphases. If, for example, a series of tests are done at different temperatures,the quantitative results can be “all over the place” and a lot of tests will berequired to find a working hypothesis to explain the results. But if 100 mlof the starting aqueous solution are mixed with 1 ml of solvent, the chosencomposition of the aqueous phase will change very slightly, while that ofthe small organic phase can change very significantly. Thus, three to fourtests at different temperatures should give a clear indication of the effect ofthat variable for the particular chosen aqueous composition.

The experimental procedure is also simpler for processes in which thesolvent added is composed of a single component, such as butanol, pentanol,methyl iso butyl ketone (MIBK), and so on. But, for other processes, thecomposition of the solvent phase added can be quite complex by itself andmay present a large number of additional components and parameters, suchas the nature of the extractant (i.e., one particular tertiary amine from thedozens of tertiary amines commercially available), of the modifiers (i.e., oneof many long-chained alcohols available for such duty), and of the diluent(i.e., a light, saturated hydrocarbon), and the relative weight ratios of thesethree classes of components.



In the typical practice of solvent extraction process development, onewould generally start with a screening procedure. (

Even my granddaughterknows by now that, in real life, the Princess would have to kiss many Frogs beforeshe would find, maybe, her Prince

.) This “screening” procedure is generallystarted with one effective composition “formula” found in previous publi-cations, or in the suppliers’ recommendations. This formula may not neces-sarily be the optimal composition for the specific case studied, so that some“exploration tests” with moderate changes outside this range should be donepreferably before any specific commitment. But the prevailing attitude hasoften been: “Let’s start with the composition that works, and we will opti-mize later.” But as often happens, everybody is too busy “later” to look backat this exact composition. This is a well-known pitfall.

It has also been observed that the chemical behavior of some extractants(in particular tertiary amines) does change as the “new” reagent (straightfrom the bottle) is “aged” after a few dozens cycles of loading/regeneration.This change, which may include a significant shift in the equilibrium curve,can be due most probably to the elimination of some traces of impuritieswhich remained in the “new” reagent from its synthesis, and possibly alsoto the oxidation of unsaturated bonds in the experimental manipulations.Since the plant will be working eventually with an aged extractant, thetesting conditions and results should reflect that change from the beginning.

An additional form of aging occurs in functioning plants due to accu-mulation of certain impurities in the solvent cycle. Although a continuouspurification procedure is generally used on a side stream, there is an eco-nomic limit to such purification and any plant has to live with a certain levelof impurities in the solvent. This effect is difficult to reproduce from theseearly tests, but has to be accounted for in the design safety factors.

6.2.4 Solid–liquid equilibrium system

Solid–liquid

reversible

equilibrium data are regulating many processes. Allthe metallurgical transformations relate, in fact, to this field, but the hightemperatures of more than 1000ºC are considered as a “far away situation”by most chemists and chemical engineers. Some chemical industries aretouching these high temperatures, but most remain below 200ºC and, in thisrange, these systems relate to solid dissolution, precipitation, and crystalli-zation, which are widely used in the various inorganic industries, mineraltreatments, and also in the natural sugar and sweetener industries.

In all these processes, the

saturation concentration of one variable component

depends also on the concentration of the other components present, in additionto the physical parameters of temperature, absolute pressure, and non-con-densable gas. The experimental determinations of such saturation concentra-tion can be rather simple, in principle, if only one component is precipitatingor dissolving, while the other components are remaining as parameters eachin its respective phase. (Note that the “limiting conditions” technique men-tioned above should also be used in such experimental determinations).



However, in many other cases,

two components

may change phase simul-taneously in certain ranges and the experimental program becomes morecomplex. Some solids are also precipitating in the

hydrated form

, taking withthem some of the water into the solid phase and contributing to furtherchanges in the concentrations in the solution. Furthermore, there are impor-tant cases of double-salts precipitation at certain concentrations. For exam-ple, the conditions for the precipitation and for the decomposition of Car-nallite crystals (hydrated double-salt of KCl and MgCl

2

) are the key featuresof the potash industry from the Dead Sea brines as mentioned in Chapter 4.Kainite and Langbeinite crystals are important hydrated double-salts foundin mined potash deposits containing magnesium sulfate and, therefore, theyhave been investigated in great detail to optimize potash recovery processes.Various degrees of

supersaturation

are always of major concern (see below).It is important to note that, in such cases, many of these solid precipitates

can be clearly identified and quantified by established mineralogical tech-niques, in addition to the usual chemical analysis methods. Thus, the collab-oration of a mineralogical laboratory equipped with all the usual microscopesand x-ray diffraction equipment can be a great help in such R&D programs.There was a time when radioisotope tracers were also used in such researchin many research labs, but this technique can be risky if it is not done with allthe special equipment, and it apparently went out of fashion.

6.2.5 Reversible and nonreversible equilibrium

In all the processes mentioned in this chapter, whenever a

reversible equilib-rium

is expected, the determination of the quantitative

relations

of the con-centrations at equilibrium (or at saturation), in various conditions and in thechosen range, is sufficient at least for the preliminary process design anddemonstration stage. However, in many other cases, the reaction involvesfirst a

nonreversible change

(such as one or more strong, one-sided reactions,i.e., neutralization) and then the equilibrium is established between theresulting phases. This order of reactions should be taken into account, andit may complicate further the experimental design.

Therefore, one can appreciate the importance of the process working defini-tion discussed in Chapter 5 in order to keep the experimental program withinaffordable limits.

6.2.6 Chemical equilibrium laboratory tests

As discussed in Chapter 5 in relation to the feasibility tests, most of thechemical equilibrium data can be determined in standard laboratory con-ditions, in rather small batches (in the hundred grams range) unless alarger quantity of one of the resulting phases is required for further testsor evaluation.

Each test consists of bringing into contact, in the specified conditions,proportional quantities of the different “inlet streams” at the assumed



compositions. After the different reactions and/or mass transfer haveoccurred, the equilibrium is established and the phases are separated (ifneeded); the different phases are sampled and the

compositions and thephysical properties of the different phases

analyzed.But it should be realized that with “real systems,” the total data collected

from each such test, representing one “equilibrium point,” amounts to pos-sibly

10 to 20 numbers

. The recording and presentation of all the differentnumerical data sets in the experimental report can be only in the form ofsystematic tables. However, the correlation of this data for all the pointscollected is not straightforward, as it depends mainly on the way in whichthe data will be used in further calculations (sometimes many years later). Thisimportant fact of life should be recognized. Unfortunately, in many casesencountered in the past, certain parts of the data were lost on the way, astheir future use was not clear to those editing the experimental reports.

6.2.7 Experimental difficulties in chemical equilibrium tests

Possible experimental difficulties can derive from the following causes.Establishing Equilibrium — Absolute equilibrium is, by definition,

never reached, as its approach is asymptotic. Chemical engineers work withpractical equilibrium, which can differ slightly from the absolute value by afew tenths of one percent, relative. In almost all cases of industrial interest,a practical equilibrium should be reached in a matter of minutes. Therefore,a contact time of 10 to 15 min in a test, before sampling, should assure apractical equilibrium.

In some particular cases, wherever a doubt exists, the tests can berepeated with different contact times, say 3, 8, and 15 min, and the resultscompared and interpolated to determine the contact time required in thisparticular contacting mechanism. A slower mass transfer rate can also resultfrom the adsorption, precipitation, or collection of impurities on the interfa-cial area, or in the adjacent “double layer”; this situation should be recordedand, if possible, corrected.

At a later stage, when the actual plant design will be considered, theexact contact time required to obtain the desired result will need to bedetermined and optimized in relation to the contacting conditions in thechosen equipment (see Chapter 10, Section 10.5). For some items of equip-ment that are handling very large flows, this contact time can be animportant factor, as every second would be cost significant. But suchoptimization can only be done in direct relation to the type of equipmentchosen and to the designed conditions for the contact and for the subse-quent phases’ separation.

Supersaturation — This is often creating additional complications inequilibrium operations involving solids, by biasing the solubility’s levels.Although the physical causes of “natural” supersaturation are not reallyknown, there are effective empirical ways to “break” the supersaturationand reach practical equilibrium (such as “seeding,” for example). Before



undertaking an extensive testing program, these techniques need to be triedand confirmed in every case to obtain absolute data.

On the other hand, one should remember that a controlled level ofsupersaturation is an essential factor in the design and operation of contin-uous crystallizers and that it can also be put to use for other process sepa-rations. In one specific case, a high level of “natural” supersaturation wasfound and exploited for an interesting process separation. A double decom-position reaction yielded two solids products, one of them (A) precipitatedimmediately and while the other (B) was maintained in solution by thesupersaturation for a period of time sufficient to separate the (A) solids bycentrifugation.

Sampling Problems — Every multiple phase contact/equilibrationshould be followed by a complete phase separation before the resultingphases are sampled. Imperfect phase separation (entrainment of small quan-tities of one phase into another) is a common cause for serious problems,first in the reliability of the data obtained from the experimental work andlater in operation of the continuous industrial equipment.

When small-scale tests at nonambient conditions are done in closed lab-oratory containers, it is not always possible to separate and sample thephases inside. If a mixture is taken and separated outside, i.e., in a centrifugetube, the contact conditions may change (temperature, pressure) and theequilibrium can be shifted before the phases can be separated. This experi-mental problem is not always recognized and may result in erroneous results.In such cases, the size of the test rig may need to be increased.

Analytical Issues — By the time the samples have reached the analyticallaboratory, the temperature/pressure conditions have changed and a samplecan separate into a nonhomogeneous mixture of phases. This possibilityshould be suspected and checked in the analytical laboratory before a smallaliquot is taken out for analyses. If this happens, the situation should bereported, as this can have other implications in the plant. Of course, the wholesample should be rehomogenized (by heating or dilution in a solvent) beforethe aliquot is removed.

6.3 Dynamic flow conditionsContinuous reactions or separations, which are dependent on dynamic flowconditions, are generally much more complicated to study or even to fullyunderstand. For example:

• A one-phase stream containing a mixture of components is flowingthrough a packed bed of solids with a catalytic action, causing reac-tions between components in the flowing stream.

• A countercurrent contact between a gas stream and a liquid stream,which allows reactions to take place, and a small amount of a certaincomponent is changing phase in either direction (see Section 6.2.2).This operation can be done in a packed bed column or in other



types of contact equipment and can be used either to “wash” anexit gas stream or to “strip” a liquid stream from an undesiredvolatile contaminant.

• Some thermal energy is introduced into a reaction mixture in theform of the combustion gases from a direct flame, from a plasma, orby induction microwaves.

• A multiple-phase mixture, resulting from a reaction in a very shortmixing zone, is separated continuously while flowing through a sep-arator, such as a gravity decanter, a cyclone, or a centrifuge.

6.3.1 Design data required

The flow conditions (velocities and paths) determine both the residence timeand the contact conditions affecting the interfacial mass transfer, such as theturbulence or the shearing forces, the differential gravity or G-forces, or atemperature gradient.

The design data required to link quantitatively these flow conditionswith the final results obtained can be either:

1. Rates of reaction and of mass transfer, which determine the chemicalcomposition of the different phases in the resulting stream(s).

2. Physical separation between the different phases in the exiting streams.

6.3.2 Simpler processes

Fortunately, many of these mechanisms of industrial interest were straight-forward enough and have been extensively studied. For example, many ofthe catalytic reactions in a gas mixture flowing in a packed column, or thechanges in a solution flowing through an ion-exchange resin column, can besimulated in relatively small continuous test equipment. The scale up of theperformance of a gas cyclone or a liquid cyclone can be predicted from small-size continuous tests (see Chapter 4, References 37 to 39). The separationresults in a continuous centrifuge (of most types) can be evaluated fromsimple tests with a small, bench-scale machine.

6.3.3 Theoretical models

Theoretical models allow the simulation and data generation from “standard-ized” batch tests in some other widely used mechanisms that have beenextensively researched. For instance, the mass transfer occurring in the con-tinuous solid–liquid and liquil–liquid contacting inside mixed vessels canbe reliably designed from the kinetic batch reaction curves obtained in bench-scale tests in well-defined mixing conditions.

Batch Aerobic Fermentation — A particular case of increasing industrialimportance is the batch aerobic fermentation involving the mixing of a liquidsolution with dispersed microorganism particles, chemical additives, and air



bubbles. In such a process, from the chemical engineering point of view,oxygen from the air bubbles is continuously dissolved and consumed by themicroorganisms (the “bugs” in operators’ jargon), CO2 is generated andevaporated, carbohydrates are reacted and consumed, a soluble valuable(desired) component is produced, and a lot of other side reactions may beoccurring, all simultaneously with the release of heat. A significant coolingcapacity is critical. The flow rate of the air, the pH, and the temperature ofthe mixture are generally maintained and controlled by external means andthe excess gases are vented. Mixing is very important in maintaining theaqueous solution more or less uniform; it can be internal or external and isgenerally combined with the cooling system (jacket or heat-exchangers).

The batch period is a matter of days. Considering a large tonnage plant(say, 50,000 metric tons/year [MTY]) with a batch turnover of, say, 4 days, anda product concentration of the order of 10% in the fermentation broth, the netinternal volume inside all the fermentors is considerable, about 6800 m3 or 34fermentors of 200 m3 each. Therefore, any improvement in the average batchperiod or in the final broth concentration can have a serious economic effect.

The hydrostatic pressure at the bottom of such a large fermentor (say, 5m diameter and up to 10 m in height or even more) is an important operatingparameter. It affects not only the supply pressure and, therefore, the cost ofthe compressed air, but also the solubility of the different gases in the solutionand possibly also the biological functioning of the microorganisms. Differentmodels of large fermentors are used in industry, each with its apparentadvantages and disadvantages. (Only apparent since many of the importantfeatures relevant to their operation have not been released for publicationby the corporations operating them.) In any case, the internal inspection andperiodical cleaning is essential.

Figure 6.1 illustrates the principle of a draft tube circulation with a cool-ing jacket, which is using the inlet air in the draft tube to promote thecirculation of the media. The air/liquid contact inside the draft tube is short,but at a higher turbulence regime. Such type of fermentors have limited sizeand limited cooling capability and, therefore, they were used mostly forsmaller production capacities, since their upscaling is estimated to reach alimit around 60 to 100 m3.

Figure 6.2 shows the main features of a fermentor in which the com-pressed air is sparged from the bottom and an external pumping circuit takesthe media around through the heat exchangers. These features have moredesign options and scale up possibilities, but the passage of the microorgan-isms through a (positive flow) pump and through the heat exchangers hasbeen hotly debated.

The composition of the solution in the batch fermentor is changing allthe time and is monitored by the operator to detect any unexpected trend.As the final trend in composition is asymptotic, the main operating issue ishow and when to stop the “reaction” (“dropping” the fermentor), since in manycases, the later period of operation produces little valuable component buta lot of impurities, which can complicate the recovery.



Figure 6.1 Fermentor with a cooling jacket and draft tube circulation.

Figure 6.2 Fermentor with sparging air and external cooling cycle.

gases out

froth

air in

CW out

CW in

coolingjacket

drafttube

gasseparation

air in

CWin

gases out

gasesseparation

cooler



In most new implementations, a batch fermentor is a prudent startingchoice, but it is generally expected that when the industrial process will bewell in hand, a number of such fermentors (four to eight) would be connectedand operated in series in a continuous fashion. This possibility should be abasic condition for the study and that option should be provided in the plantdesign. Note that an industrial setup should also include a smaller special“inoculum” fermentor and one or more nonaerated “drop-tanks” into whichthe content of a finished fermentor is transferred to stop the fermentation,in addition to means for pasteurization (“steaming”) of all incoming streamsand all equipment and piping, an acceptable waste disposal treatment forthe “bugs,” and, in many cases, the supply of chilled water.

Once a particular process is defined and a model of fermentor is chosen,the study and design of quite large industrial units can be done from astraightforward quantitative model based on the data generated in a pilotfermentor of 10 to 100 L. Such a pilot is often made in the form of very highvertical glass pipes of 7 to 10 cm diameter, with induced circulation toduplicate the changing hydrostatic pressure effects.

Separation of Solids — The rate of separation (or concentration) ofsolids from a slurry in a continuous solid–liquid thickener depends on the“filtering” velocity of a liquid flow through a dilute solid bed. It has beenmodeled by Kinch18 long ago and can still be calculated from a standardizedslurry settling curve in a 1 L graduated glass cylinder. This method is usedroutinely for the study of the effects of flocculating agents or other pretreat-ments on the settling rate of the slurry and on the capacity of the thickener.(See Chapter 5, Figure 5.2.)

Vacuum Filters — Large industrial continuous vacuum filters can bedesigned from standardized, bench-scale, batch-filtering tests.

Rate of Continuous Separation — The specific rate for the continuousseparation in industrial liquid–liquid settlers can be predicted from stan-dardized batch tests following the Barnea-Mizrahi model.19–23

6.3.4 Special test rigs

Despite the above examples of the better-known technologies, there are stillmany cases in which the study of a new system can only be done in a smallspecially designed continuous test rig. In such installations, the contact param-eters and the flow conditions (velocities and paths) should be changeableand controlled exactly and the resulting streams should be separated andsampled, then analyzed.

The design of this special rig should be based on a theoretical model thatwill allow to separate, as far as possible, between the different assumed phys-ical–chemical mechanisms, such as:

• Mixing and dispersion of phases• Flow of the continuous phases near or around the surfaces of dis-

persed solids or liquid particles



• Forces causing the physical segregation of dispersed phases, and/orthe coalescence of liquid droplets, etc.

The results of such tests should give a good holding on the scale-upand sizing of conventional industrial equipment, such as mixed tanks, set-tlers, or centrifuges.

Flash Dryer — An important example for producing powders fromsolution would be a “flash dryer.” A more complex case is the drying ofvegetable protein and similar organic concentrates (particularly wheat glu-ten) that has to be done in industry in a set of severe limiting conditions.The high starting moisture gives a messy sticking consistence to the feed inthe dryer, the so-called “dry” powder must retain a relatively high minimummoisture in order to maintain its “activity” for later use, and a maximumoperating temperature and a maximum residence time should be maintainedin the heated zone, as any overheating would damage the product.

Such performance can be done, for example, in a so-called “ring-dryer”in which a very large flow of air is circulated around at a controlled temperature(Figure 6.3). This air stream passes through a mechanical “disintegrator” intowhich the protein concentrate is injected together with a stream of hotcombustion gases. The small wet particles formed in this very short shock

Figure 6.3 Main elements of a “ring dryer.”

bag filter

powderproduct

fan

classifier

hot gasessupply

wet gasesoutlet

wet feedmaterial

disintegrator

thermalinsulation



treatment are coated with recycled drier dust and are entrained by the hotair flow into the ring for an average number of turns (residence time). Asmall side stream is removed and directed to a classifier that concentratesthe dried particles collected from the air bleed stream in a bag filter. In viewof all these essential preconditions, such processes can only be studied anddemonstrated in a special pilot rig, which should be flexible enough to repro-duce the different sets of operating conditions, while using real vegetableprotein concentrates. Most suppliers of this type of equipment are equippedwith this pilot rig and it is preferable to work with a selected expert supplier.

Cleaning of Waste Combustion Gases — Another example of the need ofspecial test rigs, which have a widely declared importance, but on which relativelylittle process information has been seriously published, is the cleaning of thewaste combustion gases from power plants and large kilns before discharge tothe atmosphere. These combustion gases are discharged from the boiler systemsin very large volumes as hot and corrosive, at a very low positive pressure,and they contain, mainly, a variable concentration of acid sulfur oxides withsome nitrous oxides and various fine ashes and other impurities. Any treatmentshould handle the very large volumes efficiently, and neutralize and eliminatethe a.m. impurities without creating any back pressure that can affect the boilersystems. From a technical point of view, the problem can be solved, but at acost! Various scrubbing systems with slurries of limestone, lime, and dolomitewere proposed and offered commercially, but all had to face the direct corre-lation between the cleaning efficiency and the bottom line cost.

One patented route25 to decrease this overall cost proposed to use ammo-nia as the neutralizing agent and to recover the ammonium salts and usethem as fertilizers. This route required an efficient scrubbing system thatcould assure that:

• Objectionable impurities would be completely eliminated.• No significant ammonia would remain with the exit gas.• A concentrated solution of ammonia salts is obtained.• No back pressure is affecting the boiler system.

A new scrubber design26 had to be developed to answer these demands,which is illustrated in principle in Figure 6.4. This is a multichamber, light-weight, horizontal scrubber. In each chamber, there is a large flow of liquidsprayed across the gas flow, maintained at a different concentration. The netflow of the solution is countercurrent to that of the gases. Ammonia gas isintroduced into the hot gas and water is fed from the other side. An auxiliaryfan is used before the chimney. The exit gases can also be reheated, if needed.

6.3.5 Indirect methods

When studying a complicated dynamic mechanism, indirect methods may some-times be used quite successfully, but the “convenience” of obtaining a lot ofdata by an indirect method may cover a basic difference in the mechanism.



When this author started a M.Sc. graduate research in Chemical Engi-neering a long time ago, he was directed by his tutor, David Hasson, to studythe mechanism of the creation of liquid drops by pressure spraying, by usinga convenient but indirect method.

The conventional experimental method used at the time consisted of acomplicated sampling procedure in order to collect drops on “targets,” fol-lowed by lengthy manual sorting under the microscope. (All of this was, ofcourse, before the automatic computer sorting available today.) The pro-posed idea was to use hot molten wax as the liquid, so that the drops wouldsolidify as spheres, and the powder could be sampled and separated intosize fractions in a conventional laboratory-sieving machine. This seemed agood idea, and after the usual literature search and study, an experimentalsetup was prepared and tried, but a prosaic problem was immediatelyencountered: the sample of wax powder was warmed and softened by thefriction on the sieve deck, which became rapidly clogged and useless. Thisgraduate researcher almost despaired when, by chance, an “old hand” visitorpassed through the faculty. Hearing of the problem, he said, “Yes, we oncehad something similar and we solved it by adding 'dry ice' to the screens.”This dry ice (solid CO2 powder) can be easily produced in the lab from aninverted pressure bottle of liquid CO2, and then sublimized while coolingits surroundings without leaving any traces. This was tried and it workedperfectly, and we started to get nice reproducible results. So, this authorreceived a very useful lesson — do not keep your problem to yourself, goand consult experienced professionals.

A lot of results were collected, which correlated nicely with the operatingvariables under study. However, such correlation was completely different

Figure 6.4 Flue gases scrubber.

Am Sulfite Solution out

premixer

last

water makeup

cooling tower

optionheater

fan

fan

flue gases in

ammonia in

first secondintermediate

compartments

flue gases out



from the partial data published by several previous researchers, indicatinga much smaller drop size and a narrower distribution. So the gist of thethesis was shifted to the explanation of such basic difference, by getting intoa more fundamental account of the different mechanisms that occur success-fully when the liquid is sprayed out under pressure and flows away whileforming filaments and drops. The molten wax method “froze” literary thedynamic process in its first stage, while with the normal liquids, the largerdrops would be catching up with the smaller ones, collecting and joiningthem, and reaching a larger size distribution (which can be relevant to thespraying of paint or inside gas–liquid contactors/scrubbers). So, the “con-venient” research technique gave very good results,26 but on a completelydifferent situation that can be relevant to certain other applications, such asthe direct spray into a reaction/combustion zone.

Thus, this author got his second lesson in R&D. Before investing a lotof work, time, and energy, one should be reasonably sure that the resultswill remain in the range of interest for the further application considered. Such atypical error is still seen today all around.

6.4 Scale-dependent operationsThese are operations in which the reaction rate, the mass transfer rate, orthe phase separation rate, obtained per unit volume of equipment, willdepend on the actual size of the equipment.

6.4.1 Vertical driving force depending on the hydrostatic height

The effect of the height of a chimney on the resulting draft is well known.The complex effect of the hydrostatic pressure on the operation of industrialaerobic fermentors was already mentioned above.

In a continuous industrial liquid–liquid settler (Figure 6.5) operatingunder gravity forces, there are two layers of separated liquids and a layerof “mixed phase” between them consisting of a dispersion of drops fromone liquid to another. The specific rate for the continuous separation, in m3

per m2 of horizontal surface, increases with the thickness of the “mixedphase” layer (since a higher combined hydrostatic force increases the pres-sure on the drops and accelerates the drop-to-drop coalescence). It is there-fore advantageous to operate with a settler of maximum height which canaccommodate a thicker “mixed phase” layer. However, there is a diminishingreturn since the quantitative function of the separation rate in m3/(m2 h) isproportional to the mixed phase thickness at the power (0.40 to 0.45). Thismechanism and optimization of such settlers was studied extensively, includ-ing the procedure for scaling up from relatively small batch tests.19–23

It was then observed that the separation efficiency of the “mixed phaselayer” per unit volume increased as its thickness decreased. One would havethought that a “flat” settler would be the most efficient, but this was, ofcourse, impossible to realize without counting on the minimum volume



taken by the separated layers. This observation led to the invention anddevelopment of improved “compact” settlers, in which sets of inclinedpartitions, made from thin PVC plates, were installed with 7 to 10 cmdistances between them (Figure 6.6). The volume between two partitionsconstituted a “flat” settler fed from one direction while the separatedphases were collected on the inclined partitions and drained into vertical“chimneys” left between the stacks. This addition of stacks of inclinedpartitions increased the overall volumetric separation efficiency of largeindustrial settlers by a factor of about 3. This reduction in the solventinventory in the plant was obviously very important when working onlarge scale with expensive solvents.

6.4.2 Wall effect

This dependence of the results on the absolute size of certain types of equip-ment is explained in most cases by a “wall effect” and is related to thenonhomogeneity caused by the inside flows near the walls or to significantlarger heat losses through the walls and the like. A larger wall effect can bequantified by a relatively larger ratio of the internal wall surface to thevolume of the equipment. This effect can be more serious whenever theoperation depends on a metastable dynamic balancing (“walking a tight

Figure 6.5 Liquid–liquid continuous settler.

mixed phase layerheavy liquid drops

passive interface

active interface

feed in

heavy liquid phase

light liquid phase

vent

nitrogen blanket option

apparentinterface

sightglass



rope”), in which a relatively short change can cause a collapse, for instancein a fluid bed solid gas contactor (see below).

6.4.3 Crystallizer

For example, it is well known that the average size of the crystals obtainedfrom a continuous industrial crystallizer increases generally with the size ofthe equipment, up to a certain maximum related to the flow mechanism andresidence time. Furthermore, this average crystal size distribution in theproduct can be very important as it determines critically the design and thedaily operation of all the downstream operations involving the crystals, suchas their filtration or centrifuging, washing, drying, screening, marketing, etc.

The driving force for the crystallization is always a certain degree ofsupersaturation which is created purposely by a chemical reaction (additionor decomposition), or by a change of temperature (mostly by cooling), or bya change in concentration caused by the evaporation of water or of anothersolvent. Such supersaturation strives to decrease by precipitation on anyexisting crystal surface.

Figure 6.6 Liquid–liquid settler with sets of racks of inclined partitions.

passiveinterface

activeinterface

feed in

heavy liquid phase

light liquid phase

vent

mixed phase

nitrogen blanket option



An additional important factor in the design and the daily operation ofan industrial crystallizer is generally a size classification system between thelarger crystals, which are ready to be removed as product, and the smallercrystals that should be left inside for some additional growing time. Thissize classification can be either on an internal or an external flow cycle, andit has to be done in unfavorable conditions, such as a concentrated, heavyand viscous “mother liquor.” In some decomposition crystallyzers, such asin the potash industry, there is a further complication as the feed is in theform of larger, lighter crystals, which have to be kept from mixing with theproduct until they are decomposed.

So, there are many types of crystallyzers in use, but their basic princi-ples are similar and relatively simple, and for each practical case the logicalchoice can be reduced a priori to two or three possibilities to be studiedfurther in detail.

Some typical illustrations of the principle of a “draft tube” crystallizerare shown in Figures 6.7a and 6.7b, and of a dense slurry “Oslo-type” crys-tallizer for larger crystals in Figures 6.8a and 6.8b.

Coming back to the “wall effect” on the product’s size, the prevailingexplanation from experts in this field is that the circulation flow of the slurryinside the crystallizer is slower near the walls. As a result, a relatively largernumber of crystal nuclei does precipitate from the part of mother liquor thatis passing in these regions than in the part remaining in the main cycle flow.There are also more “fines” generated in a smaller equipment by attritionwith the higher RPMs of the impeller. This larger number of nuclei translatesinto a smaller average size of the crystal product for a fixed productiontonnage. But this is only part of the story.

On the other hand, in most well-designed crystallizers, the amount of“fines destruction” is an effective (although somewhat expensive) operatingtool for increasing the average crystal size by reducing the number of newcrystals that are allowed to develop. Fines destruction is obtained on purposeand on demand by the dissolution of a part of the nuclei by using eitherlocal dilution or heating of the circulating “clear” mother liquor. In mostprocesses, the amount of fines destruction can be enhanced in the test unitto balance the negative wall effect and to get larger and nicer crystals. Theprediction of the final crystal size distribution in the final industrial unitfrom such small-scale tests does require a lot of experience (and perhapssome guessing) to balance between the contributions of the wall effect andthe fines destruction. Large-scale piloting with “real” streams, of course,would be much preferable, but in most projects, such piloting is not practicaluntil an advanced stage (if at all).

The final result of this dilemma is that any crystallizer installed in a firstplant with a new process is generally oversized to allow more flexibility inthe level of fines destruction and to be safer as regards the final crystal sizedistribution. As a matter of fact, many industrial crystallizers designed byreputable suppliers for new processes were finally operated at higher capac-ities, up to twice their nominal specification, after the plant’s experience was



(a)

(b)

Figure 6.7 Draft tube crystallizer.

feed

productslurry

vent

external heateror cooler circuit

feedcrystalsslurryproduct

crystalsslurry

vent

water

wastesolution



optimized and stabilized. (As the manager of one supplier said once, “You’vegot a good deal ... why should you complain?”)

6.4.4 High-temperature equipment

The study of processes based on high-temperature reactions and transfor-mations is generally done quite effectively batchwise, in small crucibles ina laboratory furnace, indicating the effects of the reactants and of the tem-perature vs. time curve in a controlled environment. This study is mucheasier when it involves a gas reacting with solids or liquid surfaces, sincethe contact is generally good and the diffusion inside and outside of thesolid or liquid is a matter of time. It is also reasonably effective for a solid–liq-uid reaction if the solids have been finely ground so that the specific contactsurface is large enough. The main process problem is encountered when thereactants are

all solids

, despite the pretreatment of fine grinding and mechan-ical compaction. In this case, the addition of a

fluxing

compound is requiredthat melts and supplies a film of liquid phase between the solids in whichthe reaction can progress. But such fluxes can generally create other compli-cations downstream.

Figure 6.8a

Crystallizer with external loop.

feed

productslurry

externalheater

or coolercircuit

bleed

to vent orcondenser orvacuum unit

1360_frame_C06 Page 102 Wednesday, May 1, 2002 3:53 PM


As a typical example, the high temperature reaction of zircon (zirconiumsilicate) with calcium oxide to liberate zirconium oxide was mentioned inChapters 1 and 5. Several proposals were published for solid–solid reactionswith small additions of different fluxes, but apparently none of these routescan guarantee the complete elimination of the silica from the zirconia.

The Gorin-Mizrahi patented route mentioned in Chapter 5 involved thereaction of molten CaCl2 in intimate mixture with fine zircon powder andwater vapors (see Figure 6.927). Previous proposals have been to react, athigher temperatures, CaO and zircon in a molecular ratio of more than 3:1to obtain a mixture of CaO,ZrO2 and 2CaO,SiO2, which will have to be treatedby wet acid to separate the ZrO2. Some published trials to operate directlyin a 1:1 ratio to obtain directly ZrO2 were not successful in meeting thedesired purity as regards the very low requirement of residual SiO2. TheGorin-Mizrahi route involved the use of a reacting film of liquid moltenCaCl2 which decomposed at a relative low temperature (less than 1000ºC),to liberate all the HCl gas and active CaO, and gave an intermediate complex,but well defined, solid double salt of CaO,ZrO2 and CaO,SiO2, on a remaining

Figure 6.8b Crystallizer with external loop.

feed

productslurry

externalheatercircuit

bleed

to vent orcondenser orvacuum unit



core of zircon. In a second kiln at a somewhat higher temperature (about1400ºC), this intermediate complex was decomposed with the remainingzircon to give solid zirconia and a CaO,SiO2 melt. After quenching andleaching in a dilute HCl solution, only pure ZrO2 remained in the solid form.

The industrial large-scale processes are done in continuous rotatingdrum kilns, calciners, and dryers in which the amount of heat losses throughthe walls is generally quite significant. Large velocity gradients exist along theradius affecting the residence time. Due to these two causes, large temperaturegradients are found both along the axis and the radial dimension.

Thus, the scale up and design of a piece of high-temperature equipmentfrom the results obtained in a small continuous test unit gets more sensitiveas the overall residence time is shorter. On the other hand, over sizing ofthis type of equipment is generally not a practical option, considering thescale of production and the control of the unit cost.

6.4.5 Failure to recognize the wall effect

In certain cases, the wall effect can become an essential component of a reac-tor’s operation. Failure to recognize that fact in the scale up can be very serious.

When this author was very young, he witnessed such an “error” in aproject managed by one of the world’s largest chemical companies. A processwas developed in which a decomposition reaction was done at a high tem-perature in a fluid bed reactor, which was maintained in a fluid conditionby a stream of combustion gases introduced from below while the feedsolution was sprayed on the bed from above. The solid product from thedecomposition was collected on the fluid bed particles, which kept growing

Figure 6.9 Triangular diagram ZrO2-SiO2-CaO.

SiO21723 C.

CaO2570 C.

ZrO2 -2715 C.

CaO,ZrO2- 2340 C.

ZrO2,SiO2-1675 C.

various calciumsilicates zone

ZrO2zone

CaOzone

Ca Zirconatezone

CaO,SiO2

1540 C.

2 CaO,SiO2



on the upper layers of the bed, and were taken out with a bleed stream ofthe coarser particles accumulated in the bottom part of the bed. The chem-istry was simple, but the local conditions inside the reactor were quiteheterogeneous and required a systematic vertical circulation to take thegrown coarser particles downwards. This circulation was obtained in a pilotreactor of 2-ft diameter, most probably by the wall effect, since the upwardsgas velocity near the wall is always much greater causing a vertical displace-ment in both directions. This pilot fluid bed could be maintained quite stableand the test results obtained were reasonable. However this essential effectwas ignored when the reactor was scaled up and built into a 50-ft diametertower. This catastrophic error led to a complete failure to perform, as thefluid bed was basically unstable with particles growing and growing in theupper layers while smaller particles were removed from the lowest layer. Ifthis issue had been recognized in time, a modified design with inducedcirculation could have been successful, but a new plant was left to rust anda very large investment went down the drain. Needless to say, the reasonsfor this failure have never been publicly explained to the profession, butfollowing such a shock, all the R&D projects in the chemical industry in thearea were shelved for quite a few years.

6.5 Reporting results from the experimental program6.5.1 Frequent partial reports

It has been noted (in Section 6.1.4) that one of the main bottlenecks ofany development project is always the calculation of the practical impli-cations of the results obtained from the experimental work and theirpresentation by the process engineering group. (The professional joke refersto the period in which a process engineer is requested to work 24 hours a dayand then continue the work through the night.) If these results can be madeavailable in a series of successive self-contained reports, each dealingwith one section of the process block diagram, the process engineeringgroup can start to correlate and work out these results as they come,making better use of their limited resources.

It is, therefore, important to agree on a transmittal procedure, whichcan include eventually the transmittal of draft reports (with due reserva-tions) if certain details are still not available. It is also important to identifyclearly these reports as any other project documents with the code number,revision number, date of issue, and name of the responsible person forfurther contacts.

6.5.2 Complete reports on the experiment part

In many projects, it has been seen that such experimental reports werehandled and written as internal memos of current value only. The authorsof these documents seemed to assume that the limited number of readers



should remember all the details of “last week’s discussions” and, thus,there was no need for further detailing. Such practice often caused seriousmisinterpretations.

But more importantly, these experimental results have been often retrieveda few years later for further studies in order to improve or expand the plant’soperation. In many cases, unfortunately, they could not be used for lack ofcritical factual information. It is therefore very important that all these exper-imental reports are written as self-contained complete scientific reports, whichcan be used also by a “new guy” who has just arrived on the project.

They should include full details on the purposes, the procedure, thematerials, the sampling and analytical methods, the numerical results, thecalculations procedure, any reference documents, the names of the respon-sible personnel and all the participants, and any observation or reservationor recommendations as regards the value of the results.

The few extra hours required for a complete report would be wellinvested and would be recovered, in any case, when the “process package”is prepared (see Chapter 7), although possibly by a different team.

6.5.3 Implications of the results

Finally, it is important as well to prepare and present a comparison of thenumerical values from the experimental results actually obtained in the testswith the assumptions or extrapolations used by the process engineeringgroup in the preliminary process working definition (see Chapter 5, Section 5.1).

Reasonable differences can be expected and the overall effect can beevaluated readily in a recalculation of the balances with the already availablespreadsheets. But if these differences or their implications are larger andmore significant, a review meeting should be called to decide on any changein the program.


• There is not much point in designing and starting any significantexperimental program without performing first the process engineer-ing analysis and being reasonably sure that the results would remainin the range of interest for the further application considered.

• The main purpose of the experimental program is the collection,correlation, and presentation of the design data that is specificallyneeded for the new process design and optimization in the limitedrange of variables of practical interest. Another important purposeis to observe possible, but unexpected, problems that can occur andthat should be dealt with.

• If representative samples of the actual raw materials cannot be readilyprocured, an experimental program on “synthetic” mixtures can onlybe done as an exploratory work for the preliminary process design.



• Since, in most cases, there are more than two components presentin each phase, one has to decide from the start which two compo-nents are the variables under study while the other components areto be considered as parameters for the purpose of the present pro-cess design.

• Very hot organic liquid or vapor “heat carrier” can be introduced indirect contact with the corrosive process stream. After heat transferand equilibration, the organic liquid is separated, removed, washed,and reheated in a separate boiler made of cheaper materials.

• The experimental technique called “limiting conditions” make it eas-ier to study, specifically, the effect of one variable at a time.

• Many of the solid precipitates can be clearly identified and quantifiedby established mineralogical techniques in addition to the usualchemical analysis methods. The collaboration of a mineralogical lab-oratory can be a great help in a R&D program.

• With “real systems” testing, the total numerical data collected repre-senting one “equilibrium point” amounts to possibly 10 to 20 num-bers, and its recording and presentation can be only in the form ofsystematic tables.

• A 50,000 MTY fermentation plant with a batch turnover of 4 daysand a product concentration of the order of 10% in the fermentationbroth, needs 34 fermentors of 200 m3 each (5 m diameter and up to10 m high). The hydrostatic pressure at the bottom is an importantoperating parameter.

References1. Schweitzer, P.A, Ed., Handbook of Separation Techniques For Chemical Engineers,

McGraw-Hill, New York, 1979.2. Henley, E.J. and Seader, J.D., Equilibrium-Stage Separation Operations in Chem-

ical Engineering, John Wiley & Sons, New York, 1981.3. Davis, G.A., Separation Processes in Hydrometallurgy, Society of Chemical In-

dustry, Ellis Horwood, London, 1987.4. Rousseau, R.W., Handbook of Separation Process Technology, John Wiley & Sons,

New York, 1987.5. Wankat, P.C., Equilibrium Staged Separations, Prentice Hall, New York, 1988.6. McCabe, W.L., Smith, J.C., and Harriot, P., Unit Operations in Chemical Engi-

neering, 5th ed., McGraw-Hill, New York, 1993.7. Humphrey, J.L. and Kelier, G.E., Separation Process Technology, McGraw-Hill,

New York, 1997.8. Seader, J.D and Henley, E.J., Separation Process Principles, John Wiley & Sons,

New York, 1998.9. Khoury, F.M., Predicting the Performance of Multistage Separation Processes, 2nd

ed., CRC Press, Boca Raton, FL, 1999.10. Moriyama, T. and Sakaki, M., Vapor liquid equilibrium of hydrochloric acid-

calcium chloride-water systems (in Japanese), kogyo kagaki zasshi, 64, 1877-1878, 1962, (see also French Patent 979,790, 1965).



11. Tyshotskaya, O.V. and Grinstein, I.M., The system HCl-H2O-CaCl2, sborniktrudy vese. nauchn, issled inst gidro sulfitn prom. (Russian), 13, 184–202, 1965.

12. Mizrahi, J., Barnea, E., and Gottesman, E., Production of concentrated HClfrom aqueous solutions thereof, Israel Patent, 36,304, 1972.

13. Lotzch, P. and Scherz, G., System HCl-H2O-MgCl2, Chem Technol. (German),339–340, 1973.

14. Kolek, J.F., Hydrochloric acid recovery process, Chem. Eng. Prog., 69, 47-50,1973.

15. Lo, T.C., Baird, M.H.I., and Hanson, C., (Eds.), Handbook of Solvent Extraction,John Wiley & Sons, New York, 1983.

16. Ritcey, G.M. and Ashbrook A.W., Solvent Extraction, Principles and Applica-tion to Process Metallurgy, Vol. 2, Elsevier, Amsterdam, 1984.

17. Rydberg, J., Musikas, C., and Choppin, G.R., Principles and Practice of SolventExtraction, Marcel Dekker, New York, 1992.

18. Godfrey, J.C. and Slater, M.J. (Eds.), Liquid-Liquid Extraction Equipment,John Wiley & Sons, New York, 1994.

19. Barnea, E. and Mizrahi, J., Compact settler gives efficient separation of liquid-liquid dispersions, Proc. Eng., 60–63, 1973.

20. Barnea, E. and Mizrahi, J., Separation mechanism of liquid-liquid dispersionsin a deep-layer gravity settler (4-part series), Part 1: The structure of thedispersion band; Part 2: Flow patterns of the dispersed and continuous phaseswithin the dispersion band; Part 3: Hindered settling and drop-to-drop coa-lescence in the dispersion band; Part 4: Continuous settler characteristic,Trans. Inst. Chem. Eng., 53, 61-69, 70-74, 75-80, 83-93, 1975.

21. Barnea, E. and Mizrahi, J., The effects of a packed-bed diffuser precoalesceron the capacity of simple gravity settlers and on compact settlers, paper Proc.Int. Solvent Extraction Conference, Toronto, 374–384, 1977.

22. Barnea, E. and Mizrahi, J., A generalized approach to the fluid dynamics ofparticulate systems, Part 1: General correlation for fluidisation and sedimen-tation in solid multi-particle systems, J. Chem. Eng., 5, 171-189, 1973.

23. Barnea, E. and Mizrahi, J., A generalized approach to the fluid dynamics ofparticulate systems, Part 2: Sedimentation and fluidisation of clouds of spher-ical liquid drops, Can. J. Chem. Eng., 53, 461-468, 1975.

24. Clue, A.S., POB 1723, 5816 Bergen, Norway, e-mail [email protected]. Mizrahi, J., A scrubber for the treatment of flue gases, Intern. PCT Patent WO

99/20371, Washington, D.C., Appl. 22.10.97, assigned to Clue, A.S.26. Hasson, D. and Mizrahi, J., The drop size of fan-spray nozzles, Trans. Inst.

Chem. Eng, 39, 415-422, 1961.27. Qureshi, M.H. and Brett, N., Phase equilibria in terniary systems containing

zirconia and silica, Proc. British Ceramic Soc., 67, 1968.



chapter 7

Preliminary process design for a particular proposal

7.1 Process team

From this stage on, the

process engineering team

consists typically of:

• The process engineers from the promoting group, who have beeninvolved in the two previous reviews described in the chapters aboveand who will still lead the effort

• A delegate from the newly appointed corporate project manager, whoreports directly to him and will gradually take over the lead of theprocess engineering team

• A number of process engineers from a chosen engineering company,who are introduced into the project at this point

• Experienced consultants, or “freelance” specialists, as needed

The different creative and critical tasks described below have often beenreferred to as the “

basic engineering”

of the new process. They will be basedon the preliminary process definition (Chapter 5) and on the reported resultsof the experimental program (Chapter 6). All these tasks should be done inparallel, since there are strong interactions among them. Their respectiveresults will add up to the

preliminary process design package

.All the basic engineering documents will be reviewed, discussed, and

agreed with the entire project team as soon as they are produced, beforebeing issued and distributed outside this team. This procedure is important,because there will certainly be some differences of opinion among experi-enced professionals, differences that are normal in any working group. How-ever, outsiders could misunderstand these differences of opinion, as they areonly partly informed, and could attribute them to a possible lack of confi-dence in the whole project. Also, in many cases, the results from the firstround of calculations and evaluation could indicate the need for changing



some of the initial choices. Another round should be done to produce reviseddocuments, with improved results.

The final results of the preliminary process design described in thischapter, together with the economic evaluation discussed in the next chapter,will be reviewed with the relevant corporate management. Hopefully, theywill justify a “maybe” decision from this management, authorizing the con-tinuation of a working program towards a first implementation, possiblywith some preconditions. In some cases, a negative decision could resultfrom the review, putting an end to the proposal.

7.2 Process flow-sheets

The preparation and drawing of the first set of process flow-sheets (pro-duced at this stage as

revision 0

) represent the

translation

of the processblock diagram and the chemical mechanisms concepts used by the R&Dgroup into the usual chemical engineering methodology and practice ofthe chemical plant. This bridge between these two disciplines is an impor-tant

creative task

, requiring a fundamental scientific understanding of theprocess, as well as extensive experience in the design of chemical plantsand their operating practice.

These process flow-sheets will represent a

reference basis

for every pro-fessional related to the project, and they should be clear also to engineersand technicians who do not have an extensive scientific background (or mayhave forgotten it since college). In these process flow-sheets, the differentfunctional sections are presented in separate drawing sheets, each with itsdefined conditions. These drawings also include the systematic

tag-number-ing

of

all pieces of equipment

and

all the main streams

. These tag-numbers willthen be used for reference in all future project documents. Some corporationshave their own practice, but practically any one of the many numberingsystems can be used, as long as the system chosen is clear and consistent.

These process flow-sheets include only such details on the piping, valves,and instruments that are essential for an understanding of the description ofthe process operation; there is no need to include at this stage all the valves,bypasses, drains, sampling points, instruments, and automatic loops that willbe needed eventually for the convenience of the plant operations. Most of theseitems are not essential at this stage, and they may be introduced later into theP&ID (piping and instrumentation) drawings, at the detailed engineering stage.

With progress of the development project, it can often be decided (or atleast considered for alternative study) that certain pieces of equipment,streams, or control instruments should be added or removed, or that therouting of certain streams should be changed. Therefore, each of these pro-cess flow-sheet drawings will probably be revised several times at laterstages. Three or four revisions are quite common in most projects.

The following five examples of small portions of (real) process flow-sheets illustrate different typical possibilities:



• Figure 7.1 shows a liquid–liquid

extraction/back extraction scheme

op-erated at two different temperatures. Each of the two stages consistsof a liquid–liquid mixer, a phase separator (a settler or a centrifuge;it may not have been finalized at this stage), two collecting vesselsfor the separated phases, and two pumps. The solvent cycle (streams[10] and [11]) passes through three heat exchangers, one for heatingwith steam, one for cooling with cooling water, and an interchangerbetween them for energy economy. The feed (stream 1) is first heatedthen extracted at the higher temperature, and its residual stream exitsas (2). Water (15) and possibly some reagents (16) are added to thehot extract (11), and result in the back-extraction aqueous product (3).

• Figure 7.2 illustrates a single-stage,

liquid–liquid contact pilot installa-tion

, presented for actual use in an experimental program. Thus, itincludes much more relevant details that need to be referred to inthe operational procedure and measurements, such as sampling, tem-perature indication, liquid interface location, venting, etc.

• Figure 7.3 shows a process flow-sheet for a

distillation section undervacuum

, in which small quantities of a residual volatile organic sol-vent are eliminated from two aqueous streams (the product solutionand the residual solution) in two stripping packed columns. The

Figure 7.1

Extraction/back extraction scheme at two different temperatures.

Trim heater H-02 Trim cooler H-04InterchangerH-03

steam cooling water

T-01 T-02

T-03 T-04

steam

H-01

TK-01 P-01 TK-03 P-03 TK-05 P-05

To DC-01

to DC-02

P-04P-02

TK-02

TK-04

1

2

3

10

15

16

11



Figure 7.2

Pilot single-stage liq-uid–liquid continuous contact.

Figure 7.3

Recovery sec-tion for vacuum distilla-tion of residual solvent.

mixer VSD

liquid-liquidsettler

overflow

overflow

closedvent

solventsump

solvent pump

aqueoussump

aqueous pump positive VSD

aqueousout

solvent out

aqueousinternalrecycle

aqueousin

solvent in

LI

LI

LI

TI

TI

sample

sample

sample

sample

LI

raffinatesolution

productsolution

livesteam

S

S

S

LI

AAA TI TI

LI

TI

water towaste

livesteam

to raffinatetank

toproduct

tank

lightvaporsrectifier

reflux

lightvapors

condenser

tosolvent

tank

S

vacuum

TI TI

TI

LI

CW



aqueous solutions are fed from the top of the columns and live steamis introduced at the bottom. The vapors from both columns, contain-ing solvent and water, are mixed and sent to the middle of a packedrectification column, which separates the solvent (top) from the water(bottom). The solvent vapors are condensed and part of the liquid isrefluxed. Live steam is fed below the packing layer and water isremoved from the bottom. The condenser is connected to a vacuumsystem through vacuum traps (not shown here). Four pumps areneeded to remove the four exit streams and transfer them to theirrespective tanks. Since the operation of such pumps that are suckingliquids from a system under vacuum may be quite problematic, anexperienced designer will do everything possible to replace themwith “barometric legs” connected directly to the tanks. Therefore,such systems under vacuum are often found in the higher tower-structures in the plant.

• Figure 7.4 illustrates a process flow-sheet for the

energy-efficient sep-aration, on a relatively large scale, of an extract stream

containing a majorproportion of a “light” water-soluble organic solvent, together withwater and nonvolatile, water-soluble impurities. The extract (stream1) is first clarified by passing through a pressure filter. In the append-ed textual description, it is explained that this operation is veryimportant and that only one of two pressure filters in parallel isshown. One of these filters is in operation while the second is beingwashed and refurbished with filter-aid, but this standard feature doesnot have to appear on this flow-sheet at this stage. The stream is thenfed first to a vapor-recompression evaporator, in which a great partof the volatile organic component can be evaporated in such condi-tions in which the vapor pressure of the water is still very low. Thecondensed solvent (10) flows to the recycled solvent tank and theremaining solution (2) passes into a double-effect co-current evapo-rator, heated with indirect steam in the first effect. Each effect is aforced-circulation evaporator, consisting of a vertical heat exchanger,a vapor–liquid separator, and a circulation pump. The organic vaporsfrom the first effect (12) at the higher temperature are condensed inthe heat exchanger of the second effect, and the organic vapors fromthe second effect (13), at the lower temperature, are condensed withcooling water. The remaining aqueous solution (4) still contains somedissolved organic and, thus, it is reheated and sent to the middle ofa packed distillation column, with a steam-heated jacket at the bot-tom and a condenser with reflux at the top. All the solvent recoveredfrom these four successive operations are mixed in the recycled sol-vent tank. Such a complicated flow-sheet is justified, or in fact dic-tated, by the allowable cost of the energy consumption in this process.

• Figure 7.5 illustrates a process flow-sheet from a different field, the

preparation of dry granules

of zircon and CaCl

2

, which constitute thestarting section for a process described earlier (see Chapter 5,



Figure 5.2). It starts from the periodical reception of the merchantzircon sand concentrate in “big-bags” and its transfer into a silo. Fromthere, it is fed at a controlled rate (1) to a wet ball-mill, where it ismixed with a carefully controlled stream (2) of a concentrated solu-tion of CaCl

2

. In the wet grinding mill, the zircon sand is reduced tovery small particles in a concentrated slurry, which is passed througha wet magnetic separator into a holding and blending mixed tank.From there, this concentrated slurry is fed to a fluid-bed agglomer-ator/dryer, in which hot combustion gases are introduced from thebottom, below the “grid,” and part of the gases from the top arerecirculated to maintain the FB and the partial pressure of the watervapor. In this case, complete evaporation of the water is not wanted;on the contrary, a certain concentration of water must be left in thegranules, to prevent the beginning of thermal decomposition of theCaCl

2

and the liberation of gaseous HCl in the granulator. A partial

Figure 7.4

Complex separation of a volatile solvent from an aqueous solution.

Aqueous residual solution

solvent stripping column

steam

pressure filter extract

vapor recompressionevaporator

condenser

CW

refluxrecycled

solvent tank

1

2

3

4

5

10

1213

12

1015

17

4

3

steam

CWsteam

22

21

double-effect cocurrent evaporator



elimination of the water is sufficient to produce hard granules thatcan be transferred to the next stage of the process.

7.3 Preparation of an overall detailed description

This is a written document that describes the chemical and physical mech-anisms of the various sections of the process, its operation, and its control.It should include

all the information

that is available at this stage, organizedin a useful format, so that any new member of the team can catch up on the

reference data basis

.This presentation should start by explaining the origin and nature of the

raw materials and additives that are entering the process. It should includeany particular reasons for their choice; their

average nominal compositions

,which will be entered in the calculations that will follow, and their possibleor expected

variations

(natural or seasonal), which have to be accounted forin the plant’s operation and process control.

This description should then systematically cover every piece of equip-ment chosen (at this stage); the reactions and/or the separations expectedin it, its functioning and operating control, and all the possible problemsthat should be taken into consideration in its final design.

The document should conclude by detailing the properties required fromthe products,

in order of importance

, and also the requirements and the (pos-sibly) acceptable methods for disposal of the waste streams.

Figure 7.5

Preparation of dry granules of zircon with CaCl

2

.

combustionchamber

fuel 1

fan-02

FB aglomerator/dryer

dried granules

wet grinding ball mill mixedslurrytank

40%CaCl2tank

Zirconsilo

S-01

M-01

MT-01

MT-02

M-02

fan-01

P-01

P-02

1 2

3

feeder M-09

to stack

crane M-08

big bag

wet magneticseparator M-12



7.4 Listing of all the main process streams

This list includes all the

main process streams

and also the

main service streams

,as these appear in the process flow-sheets, each with a specific name andnumber. One should remember that these names and numbers will be usedfrom now on, hopefully by hundreds of individuals and by the plant’soperating staff, for many years, long after the designers’ job is finished.Therefore they should be chosen carefully, to be as clear, descriptive, andeasy to remember as possible. (In situations where this requirement has notbeen met, this can became very annoying to users, who then start to “nick-name” these features with their own private code.)

Each stream may retain its number as it goes in and out of a piece ofequipment, although its temperature or pressure may change, but it shouldget a different number wherever its

nominal

composition is expected tochange. Note that while a certain stream is passing through a bufferingstorage vessel, its

nominal

(average) composition should not change, but its

instantaneous

composition may change. Since the extent of such changes willprobably be analyzed later in the process control modeling, it would be agood practice to give a separate number to the exiting stream.

7.5 Material and heat balances

Once the first revisions of the process flow-sheets, the description, and thelists of streams are more or less in workable condition, the next step will bethe preparation of spreadsheet tables for the design material balances andfor the heat balances, including all main components in all main streams(process and services).

First, the

bases

of the detailed process calculations have to be chosen andagreed upon, for the record. These are generally the

nominal plant yearlycapacity

and the

compositions of input streams

, although other bases are usedoccasionally. The nominal plant yearly capacity can be based either on theraw materials input, or on the products output. Note that the second alter-native may appear neater, with nice round yearly production figures (somewould say too nice!), but it could require more trial-and-error iterative runs,as the process results are optimized.

These design balances are generally calculated for one hour of

steady-state nominal flows

, while the economic calculations (see Chapter 8 below)will be done on a calendar year basis. The average number of productionhours expected per year, at the

steady-state nominal average rate

should bedecided and recorded at the beginning. In the chemical industry, this averagewould generally be in the range of 7,500 to 8,500 hours. This number shouldbe estimated for each case, depending on:

• The nature of the process• The extent and frequency of stoppages expected for maintenance

work (for example, how often would internal cleaning be needed?)



• Any “annual shut-down” legally required for certain high-tempera-ture/high pressure processes

• The local working habits (annual leave and holidays)

The detailed process calculations needed for these balance sheets usewell-known chemical engineering tools and are based on:

• The general chemical functions (stoichiometric and/or thermodynamic)• The numerical information available on the raw materials• The empirical correlation resulting from the preliminary design data

collected in the experimental program (see Chapter 6), or from datathat may be available from other sources; such empirical correlationcould involve, for example, the reaction or separation

yields

, the

distribution factors

for mass transfer operations, and the vapor partialpressures

of various components in different conditions• Various “reasonable”

assumptions

, as

needed and agreed , which willalways be clearly marked as such; these assumptions can provide foreither (1) quantitative relations

, such as the percent recovery (split) ofa particular component or the percent of entrainment of a phase intothe wrong stream, or (2)

numerical values, such as the heat transfercoefficient or the weight percent of residual liquid in the cake froma filtering centrifuge

The sensitivity of the final results to the value chosen in any of theseassumptions (its “leverage”) should be checked before proceeding fur-ther. The stronger this leverage is, the higher the danger of a significanterror becomes. In this case, additional cross-checking and better proce-dures need to be devised and carried out urgently, in order to arrive atsafer assumptions.

The results of the

process material balance calculations will be tabulated ina spreadsheet

for all main streams

, as illustrated for a typical example inTable 7.1 for a solvent-extraction battery:

• The

nominal flow rates per hour

on a weight basis, and sometimes alsoon a volumetric basis, if needed for design

• The

compositions

in weight and percentage, including all the majorcomponents and the minor components of importance

•

All relevant properties of the stream

, such as the temperature, pressure,specific gravity, viscosity, specific heat, and possibly also some otherproperties relevant to the particular technologies used, such as thewetting contact angle, the dielectric coefficient, and the porosity

If any stream does contain more than one phase (a “plurality” of phases,as the patent’s jargon would say), the flow rates, compositions, and relevantproperties should be given for each phase separately, as well as for themixture as a whole, indicating the weight ratio between the phases.



Tablet 7.1

Typical process material balance for a solvent extraction battery

Aqueous AqueousFeed Residual

Stage E1 E2 E3 E4 E5 E6 E7 E8

Aqueous phase kg/hr

AAA 6,112 6,000 4,800 3,400 2,400 1,400 700 300 112BBB 509 499 468 448 428 418 408 398 318CCC 720 712 708 708 708 708 708 708 708Water 7,951 7,951 7,951 7,951 7,951 7,951 7,951 7,951 7,951Total 15,292 15,162 13,927 12,507 11,487 10,477 9,767 9,357 9,089Specific gravity 1.116 1.100 1.084 1.065 1.054 1.040 1.031 1.019 1.009Flowrate m

3

/hr 13.703 13.784 12.848 11.744 10.898 10.074 9.473 9.183 9.008

Organic phase kg/hr

ExtractRecycle Solvent

AAA 6,050 5,938 4,738 3,338 2,338 1,338 638 238 50BBB 211 180 160 140 130 120 110 100 20CCC 30 22 18 18 18 18 18 18 18Water 7,000 7,000 7,000 7,000 7,000 7,000 7,000 7,000 7,000Solvent 90,750 90,750 90,750 90,750 90,750 90,750 90,750 90,750 90,750Total 104,041 103,890 102,666 101,246 100,236 99,226 98,516 98,106 97,838Specific gravity 0.971 0.965 0.945 0.939 0.934 0.926 0.912 0.906 0.904Flowrate m

3

/hr 107.148 107.658 108.641 107.823 107.319 107.156 108.022 108.285 108.228

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07 Page 118 Monday, A

pril 29, 2002 3:37 PM


Aqueous phase % w/w

AAA 39.969 39.573 34.465 27.185 20.893 13.363 7.167 3.206 1.232BBB 3.329 3.291 3.360 3.582 3.726 3.990 4.177 4.254 3.499

Organic phase % w/w

AAA 5.815 5.716 4.615 3.297 2.332 1.348 0.648 0.243 0.051BBB 0.203 0.173 0.156 0.138 0.130 0.121 0.112 0.102 0.020Water 6.728 6.738 6.818 6.914 6.984 7.055 7.105 7.135 7.155

AAA distrib. A/O

6.805 6.030 5.891 6.337 5.729 5.315 4.951 5.079

BBB distrib. 16.228 19.395 22.984 26.946 30.762 34.542 38.094 34.325Net flowrate ratio

O/A 7.77 8.38 9.25 9.89 10.65 11.31 11.76 12.02

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It is important to realize that

different rows may be calculated by differentmethods and from different sources

. As the whole picture could be quite com-plex, it is a good practice to include in each such spreadsheet an automaticoverall balance check for the different recognizable components in the inletand outlet streams.

In any case, these overall balances will be needed for the “black-box”presentation (see below).

Differing from the overall approach needed for the material balancesabove, the

process heat balance calculations

should be started and presentedseparately for each of the different operations in which:

• Heat can be generated or consumed by a reaction (including com-bustion), or by a significant input of mechanical energy

• Heat is transferred between different streams, either directly by con-tact between different process phases, or indirectly in heat exchangers

For each such operation, a quantitative heat balance must be producedin any convenient format, which can be checked or modified if needed. Suchbalances should include assumptions related to heat loss to the surroundingsand the nature of any heat insulation system assumed (i.e., the area andtransmission characteristics). A typical example is presented in Table 7.2.

One should note that the heat resulting from the input of mechanicalenergy is generally small and neglected by chemical engineers in most cases(in pumps, agitators, etc.), but this could be a major item in certain opera-tions, such as gas compression or expansion, or solid grinding.

When all the heat balance results are available for the different opera-tions, they should be compared and analyzed to see if any synergetic com-bination could be possible in order to minimize the overall energy consump-tion and/or its cost. Finally, the total heat requirements are calculated andtranslated into a consumption of services (fuel, various grades of steam,cooling water) as discussed below in Section 7.7, and tabulated as in thetypical example in Table 7.3 below.

It is also advisable to join to these tables a

detailed description of themethodology

that was used in these calculations and any literature referencefor the functions used, to allow independent checking by other users. In thechoice, preparation, and description of methodology, one should take intoaccount that it will most probably be used again in the future, possibly byother engineers, when the process optimization will require a systematicscreening of the effects of the different variables (see Chapter 11).

7.6 Material handling operations

In large chemical plants, these material-handling operations, needed tobring in the raw materials supply and to send out the products of the plant,will generally require special arrangements, extra space, roads, railwaytracks, storage volumes inside the plant, etc. All these material-handling



operations are not different for a new process from those required for aconventional process, but the design options and choices can be widerwhen starting anew. A detailed description of the objective needs shouldbe presented and distributed to the team and the consultants to invitecreative proposals.

In addition, the requirements and available options for the disposal ofeach waste stream should be described in relation to the local environmentaland ecological regulations in the area (with any available dumping pond orany means for its transfer into some existing waste treatment installationsin the affordable vicinity).

Table 7.2

Typical Process Heat Balances (metric units)

Stream kg/hrm

Diff Heat kcal/hr

Example 1 FB Dryer Granulator M-02

Solids in heating from 25 to 200 1000 175 0.23 40,250Solution in heating from 25 to 200 1516 175 0.74 196,322Water conc. + evap. 809 590 477,310Heat losses loss 30% from above 214,165

691,465Combustion gases cooling from 1350 to 250

2621 1100 0.24 692,000

Fuel combustion 81.4 8,500 692,000

Example 2 First Kiln K01

Granules in heating 1707 800 0.23 314,088CaCl

2

endothermic decomposition 607 475 288,135Water conc. + evap. 101 590 59,590Heat losses loss 20% from above 132,363

794,176Combustion gases cooling from 1200 to 400 4136 800 0.24 794,150Combustion gases recycled from kiln 2 1831 800 0.24 351,552Combustion gases from combustion 2305 800 0.24 442,598Fuel combustion 46.6 9,500 442,598

Second Kiln K01

Solids heating from 1000 to 1400 1321 400 0.23 121,532Endothermic reaction 13,688Heat losses 30% loss 20% from above 40,566

175,786Combustion gases cooling from 1600 to 1200

1831 400 0.24 175,776

Fuel combustion 17.6 10,000 175,776

Clinker Cooler K03

Clinker cooler from 1400 to 200 1306 1200 0.18 282,096Air heating from 25 to 75 1792 648 0.243 282,175



Table 7.3

Typical summary table for the services required

Consumption per Stream Description Characteristics Unit Hour Year Notes

1 Process water Municipal m

3

749 5,843,000 Without recycle1-a Process water Municipal m

3

487 3,800,000 With recycle2 Boiler-feed water Own m

3

24 187,200 Make-up3 Steam 7 ata MT 167 1,300,000 Medium pressure4 Cooling water In 28°C Out 40°C m

3

34,415 268 MM Own tower5 Heavy fuel no. 6 10,000 kcal/kg MT 15 117,000 For steam6 Fuel oil no. 2 10,000 kcal/kg MT 2.7 21,000 For dryer7 Compressed air 8 ata Nm

3

3,360 26.2 MM8 Electricity Purchased kw-hr 780 6.0 MM

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Typically, the inventors and R&D personnel consider all these material-handling operations very “trivial,” and these are often neglected or ignoredaltogether in their process presentations (“the engineers will take care of thatlater”). However, although generally conventional mechanical devices, theseare in fact quite

expensive and visible

as the facade of the new plant. The directcost of all these material-handling installations can be a major considerationin many cases, or even a decisive factor for the future of a project, or at leastfor its particular location. The preparation of a clear quantitative descriptionof the operational options and their relative costs, at an early stage, couldallow all the team to think in concrete frameworks and possibly create betteror cheaper solutions.

7.7 Summary tables for all required services

The

nominal

(average) flow rates for all services will derive directly from thematerial and heat balances calculated above and will be used for the eco-nomic calculations. But the

design

quantities for the supply of services thatshould be available to the plant generally include

higher instantaneous rates

(i.e., for starting, stopping, or emergency), and possibly also a significantreserve for eventual increase in production. An important design decisioninvolves the

maximum

delivery rate designed for each service. This data istabulated, as shown in a typical example in Table 7.3.

There could also be several different possible options for the supply ofeach service. They are essentially

major cost factors

and a wide field is openfor optimization studies, to achieve the cheapest and most convenient solu-tion. Again, these issues are not different for a new process from thoseconsidered for a conventional process, but the choices and options maycertainly be wider before the process is finalized.

The services generally considered in most chemical plants are:

•

Fuel

, either for direct use in a combustion device incorporated into theprocess, or for indirect burning for the production of steam or anotherheating medium (oil, brine) in the new plant. Different types andqualities of fuel could be available and considered, from

coal or

liquidpetroleum fractions to natural methane gas. In many cases, internalwaste streams are also burned. In addition to considerations of costand convenience, the impurities in the flue gases discharged from thestack (SO

2

/SO

3

, nitrous oxides, metallic dust, and so on) or fly ashcould be a decisive factor in the choice of fuel. There could also belocal ecological restrictions, which may require intensive cleaning in-stallations and cancel the advantages of a cheaper fuel.

• Several types of

steam

(high, medium, or low pressure)

or other heatingmedia

, which may possibly be purchased from the site’s central ser-vices or from adjacent producers. With indirect steam functions, thecondensed water is returned to the boiler circuit, while when direct



steam is used in the process, the condensed water stays with theprocess streams and has to be replaced as “boiler-feed-water” quality.

•

Cooling water

, generally produced in the new plant’s own coolingtower, but sometimes received from a nearby sea or river. The max-imum supply temperature of the cooling water should be clarifiedat an early stage, since it could affect the process operating temper-ature, or at least the size of the cooling heat exchangers. In somecases,

chilled water (in the range of 4 to 15°C) could be needed andshould be prepared in a separate installation.

• Electricity is generally purchased. Only in few cases would the newdemand be large enough to justify the purchase of a generator. Eventhen, a back-up connection to the external electrical supply gridwould also be needed. Some process operations may require an emer-gency electrical provision for safety or damage control (installed andautomatically started). If this situation is expected with the newprocess, it should be emphatically stated and a separate list startedfor the electrical consumers that will need to be connected to theelectrical emergency supply.

• Compressed air, generally produced in the new plant’s own station.• Oxygen for certain reactions and nitrogen as inert gas, if needed, can

be purchased in certain cases, or have to be produced on site by anair separation installation.

• Fire-fighting water supply and rig.

The availability at the site in the quantities required, and the unit costof each of these services or possibly the need for new additional installationsfor self-supply, should be investigated, presented, and discussed.

7.8 Major pieces of process equipmentThe items of equipment in the process flow-sheets may be divided and listedseparately into four broad categories (see a typical example in Table 7.4):

1. Small standard equipment, which can be selected from catalogs froma relatively large number of suppliers, such as pumps, fans, blowers,agitators, standard heat exchangers, etc.

2. Custom-built standard equipment, which is made to order from theengineering drawings in fabrication workshops. The costs are esti-mated mostly on an empty weight basis, or even on a volume basis.For example, tanks, silos, large separation vessels, etc.

3. Major process equipment, which is detail-designed and made toorder by specialized suppliers. The preliminary selection of type,model, and size of each of the major pieces of process equipment willbe presented on the basis of a functional analysis of its duties andquantified in the above-mentioned balances (average only).



Table 7.4 Typical List of Major Process Equipment

Tag Name Size MOC** Kwatt inst. Service needed

T-01 HCl solution tank 50 m3 FRP 0 HCl soln T-02 Fuel tank 100 m3 MS 0T-03 Water tank 300 m3 MS 0S-01 Raw material silo 70 m3 MS 0 200 mt. MT-01 CaCl2 soln mixed tank 50 m3 MS 5MT-02 Slurry mixed tank 20 m3 MS 10MT-03 Leaching first mixed tank 1.9 m3 FRP 1 HCl soln MT-04 Leaching sec. mixed tank 1.9 m3 FRP 1 HCl soln MT-05 Leaching third mixed tank 1.9 m3 FRP 1 HCl soln MT-06 Lime mixed tank 20 m3 MS 10 for waste neutral M-01 * Grinding ball mill 1.80 ID 3.2 m. L RLS 150 incl. classification circuit M-02 * FB Aglom. dryer 1.48 ID 3.0 m. L MS 0 fuel +CaCl2 soln M-03 Clinker hammer mill 1.5 tph MS 15 incl. quenching C-01 * Adiabatic absorption tower 1.8 ID 8.0 m. L FRP + RL 0 water K-01 * Kiln 1 0.87 ID 12.4 m. L BL 25 fuel - max. 1000 C. K-02 * Kiln 2 0.87 ID 8.62 m. L BL 25 fuel - max 1400 C. K-03 * Clinker cooler 1.0 ID 10 m. L SS / BL 25 with air M-04 * Belt filter 32 m2 FRP + RL 50 CC cake washing M-05 * Product dryer (solids) 700 kg/h SS 3 rotary trays -fuel M-06 Cooling screw conveyor 0.1 ID 2 m. L SS 1 CW jacket M-07 Wet cake elevator 1.5 tph FRP + RL 1M-08 Overhead crane 5 mt MS 3M-09 Solids feeder 0.4 m3/h MS 1M-10 Bagging machine 1 tph - 0 50 kgs bags M-11 Dry granules elevator 2 tph SS 1M-12 Wet magnetic separator 0.8 m3/h SS 1

continued

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pril 29, 2002 3:37 PM


Table 7.4 (continued) Typical List of Major Process Equipment

Tag Name Size MOC** Kwatt inst. Service needed

P-01 CaCl2 brine pump 1.3 m3/h MS 1P-02 Slurry pump 2 m3/h MS 1P-03 Clinker slurry pump 1.5 m3/h SS 1P-04 Waste stream pump 5 m3/h PP 3P-05 Wash water pump 3 m3/h PP 2P-06 HCl solution pump A 2 m3/h PP 1P-07 HCl solution pump B 3 m3/h PP 2P-08 Fuel pumps (1+1) 0.3 m3/h MS 1P-09 Water pumps (1+1) 10 m3/h MS 5P-10 Milk of lime pump 0.5 m3/h MS 1Fan-01 From aglom. dryer 20 m3/sec MS 5Fan-02 Air to combustion 1 2 m3/sec MS 1Fan-03 Air to combustion 3 1 m3/sec MS 1Fan-04 Air to clinker cooler 0.7 m3/sec MS 1Fan-05 To stack 2.5 m3/sec FRP 1Fan-06 Air to combustion 4 1.4 m3/sec MS 1

Total 357

* = complete package** = material of construction

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4. In certain cases, the new process may require the development anddesign of a new or modified type of reactor or separator, which cannotbe procured readily from established suppliers. Of course, this willcreate an additional load on the development effort and on the in-vestment, time, and talents needed, but it could also increase theintrinsic value of the new know-how generated. If this is the case,this new equipment will obviously be at the center of attention ofthe project team.

For each major piece of equipment, a specification file will be opened inwhich this selection should be recorded, together with:

• A detailed explanation of all the possible options and the reasons forthe recommended choice of type, model, size, and any other impor-tant specification

• The selection of the materials of construction• The estimated electrical supply• The plant space needed for this major equipment can also be indi-

cated, for the lay-out studies (area and height, free space accessneeded, rigid connections)

A list of all known potential suppliers of the recommended type can also beincluded, to allow further inquiries, as needed. In certain cases, one preferredsupplier can be recommended. This critical dependency could simplify, butcould also complicate the situation, and many corporations oppose suchsituations as a matter of principle.

7.9 Main operational and control proceduresAt this stage, a detailed operational and control manual is not needed and,in any case, it cannot be delivered before the detailed engineering stage,when the P&IDs are well advanced. However, a first write-up of the mainoperational and control procedures should be prepared in relation to theprocess flow-sheets, including:

• Start-up and stoppage requirements• Any particular safety aspect of this installation (for example nitrogen

blanketing)• Waste disposal methods

Emphasis in this write-up should be on those procedures that may beunusual at the particular location, may require a major effort to develop orimplement, or may have a significant cost attached. Specialized consultantsand corporate staff should be consulted on the operational aspects of the plant.

This first draft of the main operational and control procedures shouldbe intended mostly as a reference basis for the comments of all members of



the preliminary process design team. It will be gradually developed, byadding different contributions, and presented for review with the first P&IDs(see Chapter 10, Section 10.4).

7.10 Listing of required staffAn experienced operation manager or consultant will prepare a first listof all the personnel positions that will be needed for operations (mostlyshift-work), management, supervision and control, quality assurance, thegeneration of services, plant maintenance, and any special requirement ofthe project.

For the different positions, the availability, extent, and cost of training(part of the investment), and the yearly cost of this staff (fixed operatingcost) should be estimated. This listing and discussion will be related to thegeneral industrial experience in the specific area under consideration andthe expenses (as a total) will be included in the economic calculations inChapter 8.

In many cases and remote locations, the availability of adequate staff forparticular positions cannot be taken for granted, and it may have to berelocated with special effort and extra costs.


• The preparation of the first set of process flow-sheets represents thetranslation of the process block diagram and the chemical mecha-nisms concepts used by the R&D group into chemical engineeringmethodology and practice. This bridge between these two disciplinesis an important creative task, requiring a fundamental scientific un-derstanding of the process as well as extensive experience in thedesign and operation of chemical plants.

• The overall detailed description of the chemical and physical mech-anisms in the various sections of the process, as well as its operationand control, includes all the information currently available, in auseful format so that any new member of the team can becomefamiliar with the reference data basis.

• The new process may require the development of a new or modifiedtype of reactor/separator that cannot be procured readily. This cre-ates an additional load on the development and the investment, timeand talents needed, but it could also increase very much the intrinsicvalue of the new know-how generated. In such case, this new equip-ment will be at the center of attention of the project team.



chapter 8

Economic analysis of the specific proposal

8.1 Purpose

At this stage, the only purpose of this preliminary economic analysis of theproposal is to supply information on the

profit potential

of the final plant,which is needed to justify the continued expense for its development. Thisis definitely not the kind of economic analysis that will be needed later toapprove the investment of tens or hundreds of millions of dollars in anindustrial plant (see Chapter 10).

The preliminary analysis can be done within the project team, if anexperienced “cost engineer” is available, or by a specialized consultant, orit may be subcontracted to an engineering company. It is based on:

•

The process data

contained in the preliminary design package, whichwas described in the previous chapter

•

The cost data

available in the files from previous projects•

The input from the marketing

experts •

The non-committing, up-to-date quotations

for the major equipment, ob-tained by direct contact with potential suppliers (not as formal tenders)

To save time, this economic analysis could be started on partial drafts ofthe preliminary design package, which could be supplied informally, butof course, the “bottom line” recommendation can only be completed afterthe preliminary design package is completed and ready to be formallypresented.

8.2 Preliminary estimate of the Fixed Capital Investment (revision 0)

The working methodology for the preparation of fixed capital investment(FCI) estimates is well known from textbooks.

1,2

It is also practiced in



most engineering groups with good results and need not be discussedhere in detail.

Just to recall some “fact-of-life”: For a

preliminary estimate

, the purchase,delivery, and installation costs of the

major

pieces of equipment are estimated

separately

, from the company’s own records, or from published cost correla-tions, but mostly from up-to-date quotations obtained “on-the-wire” fromsuppliers. Note that such preliminary quotations can be obtained at this stagefrom only three or four suppliers, as it is not intended to make a bid com-parison, but only to select a reasonable average cost for this task. But if oneof the quotations received from the suppliers is “way out” from the average,this could indicate a problem in the concept or the wording of the requestspecification, which should be clarified.

Table 8.1 illustrates a typical example for a preliminary small project forthe production of 5,000 tons per year (tpy) of zirconium oxide according toa novel process (Gorin-Mizrahi, described in Chapter 5, Figure 5.2). The listof equipment is taken from the preliminary process flow-sheets and theestimated installed costs for each are based from recorded data from otherprojects, with the necessary conservative adaptation and updating. Oneshould note that 90% of the installed equipment cost can be attributed toeight complete packages from specialized suppliers (kilns, dryer, ball-mill,agglomerator, etc.), including their design and operating know-how.

The sum of the installed costs of all the major pieces of equipment isthen multiplied by different

relative statistical factors

, representing the costcontributions of minor standard equipment, buildings, piping, electrical,instrumentation and control, services connections and infrastructure, engi-neering and management, start-up, and miscellaneous. These different sta-tistical factors are

individually chosen

by an experienced cost engineer on thebasis of the recorded analysis of previous projects, and are adapted to thespecific characteristics of the present case (such as its location, request forexplosion-proof conditions, large flows of gases, etc.). For the case describedin Table 8.1, it was estimated that a factor of 3.0 would be sufficient, consid-ering a lower need for detailed engineering and electrical hardware.

Separate

safety margins

(reserves) are then chosen to fit the uncertaintybuilt into the present state of project definition. These safety margins areadded to the total sum obtained above, but they will have to be reconsideredin each of the future revisions of this FCI estimate, as the process andimplementation conditions will be more focused and their uncertainty rangewill be decreased. For the case under discussion, a safety margin of 30% wasadded to reflect the early status of the estimate, bringing the total FCIpreliminary estimate to $16,510,000. This does not include the promoters’own expenses, or the cost of additional testing.

This is the usual methodology for a preliminary FCI estimate. The formatused is not critical, as a completely new format will be used later for the“real” investment budget, when it will be prepared for approval of the plant(see Chapter 10).



Table 8.1

Typical Preliminary Fixed Capital Investment Estimate

Tag Name Number Size MOC

**

Installed Cost

T-01 HCl solution tank 1 50 m

3

FRP 20,000 T-02 Fuel tank 1 100 m

3

MS 15,000 T-03 Water tank 1 300 m

3

MS 32,000 S-01 Raw material silo 1 70 m

3

MS 30,000 MT-01 CaCl

2

solution mixed tank 1 50 m

3

MS 17,000 MT-02 Slurry mixed tank 1 20 m

3

MS 20,000 MT-03 Leaching first mixed tank 1 1.9 m

3

FRP 20,000 MT-04 Leaching second mixed tank 1 1.9 m

3

FRP 20,000 MT-05 Leaching third mixed tank 1 1.9 m

3

FRP 20,000 MT-06 Lime mixed tank 1 20 m

3

MS 25,000 M-01 * Grinding ball mill 1 1.80 ID 3.2 m. L RLS 900,000 M-02 * FB Aglom. dryer 1 1.48 ID 3.0 m. L MS 1,000,000 M-03 Clinker hammer mill 1 1.5 tph MS 50,000 C-01 * Adiabatic absorption tower 1 1.8 ID 8.0 m. L FRP + RLS 100,000 K-01 * Kiln 1 1 0.87 ID 12.4 m. L BL 500,000 K-02 * Kiln 2 1 0.87 ID 8.62 m. L BL 500,000 K-03 * Clinker cooler 1 1.0 ID 10 m. L SS / BL 100,000 M-04 * Belt filter 1 32 m

2

FRP + RLS 500,000 M-05 * Product dryer (solids) 1 700 kg/h SS 200,000 M-06 Cooling screw conveyor 1 0.1 ID 2 m. L SS 7,000 M-07 Wet cake elevator 1 1.5 tph FRP + RLS 20,000 M-08 Overhead crane 1 5 mt MS 10,000 M-09 Solids feeder 1 0.4 m

3

/h MS 15,000 M-10 Bagging machine 1 1 tph - 25,000 M-11 Dry granules elevator 1 2 tph SS 10,000 M-12 Wet magnetic separator 1 0.8 m

3

/h SS 18,000

continued

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Table 8.1

Typical Preliminary Fixed Capital Investment Estimate

Tag Name Number Size MOC

**

Installed Cost

P-01 CaCl

2

brine pump 1 1.3 m

3

/h MS 2,500 P-02 Slurry pump 1 2 m

3

/h MS 2,500 P-03 Clinker slurry pump 1 1.5 m

3

/h SS 4,000 P-04 Waste stream pump 1 5 m

3

/h PP 5,000 P-05 Wash water pump 1 3 m

3

/h PP 5,000 P-06/07 HCl solution pump 2 2 m

3

/h PP 10,000 P-08 Fuel pumps 1+1 0.3 m

3

/h MS 3,000 P-09 Water pumps 1+1 10 m

3

/h MS 6,000 P-10 Milk of lime pump 1 0.5 m

3

/h MS 2,500 Fan-01 From aglom. dryer 1 20 m

3

/sec MS 5,000 Fan-02 Air to combustion 4 2 m

3

/sec MS 6,000 Fan-04 Air to clinker cooler 1 0.7 m

3

/sec MS 2,000 Fan-05 To stack 1 2.5 m

3

/sec FRP 2,000 total 4,162,500

* = complete package** = material of constructionFRP = fiberglass reinforced polyester; MS = mild steel; RLS = rubber-lined steel; BL = brick-lined; SS = stainless steel; PP = polypropylene

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But there is an additional item that is often neglected, in the experience ofthis author. That is the

purchase cost of the internal inventory

that is needed toarrive at the steady-state operation of the plant. At most, the relatively smallvalue of the “work-in-progress” is recorded, that is, the cost of the differentmaterials having intermediate compositions between the raw materials and theproducts, contained in the different pieces of equipment piping and storage. Thecost of the “work-in-progress” depends on the unit costs of the materials andon the various residence times (as an extreme case, consider for instance a solarpond in a salt operation, which takes several years to fill and concentrate).

Many plants also require auxiliary purchased materials. For example, thesolvent stock in a solvent-extraction plant may account for a quite significantpart of the FCI, depending on the unit cost of the particular solvent used andon the internal volumes required. A similar situation exists with mercury cells,resins columns, circulating active-carbon, thermal oil, etc. There is definiteroom for optimization in this area, which is not always appreciated.

This “omission” is often attributed to the fact that many certified accoun-tants do not accept the value of this internal inventory as part of the FCI, whichis used to calculate the tax-allowed depreciation and profitability of the invest-ment, and also to evaluate indirectly the cost of maintainance. Despite thebookkeeping formalities, however, almost all of the value of this internalinventory is a one-time expense, which cannot be recovered, even if the plantis terminated, and which, furthermore, will require some periodical make-up.

Another controversial issue is how to handle past and future developmentexpenses, in relation to the FCI of the first plant, which could be build on amodest scale. Again, many certified accountants do not accept these develop-ment expenses as part of the FCI. There are different practices in this regard.Most corporations have probably already included the (recorded) past expensesin their yearly balances, and they are now “forgotten.” Other corporations mayhave capitalized these past expenses as part of their investment in “specialsubsidiaries” (daughter companies, joint ventures) and these sums have toreappear in a new plant’s investment. The same issue will be related to thetreatment of (expected) future development expenses, to the point when adecision to build a plant is reached. After that point, all development expensesare generally included in the “engineering” budget, a definite part of the FCI.

Furthermore, the governments of certain developing countries encour-age the establishment of new industries (declared of national interest) bycontributing a grant of 20 to 40% of the FCI, subject to certain conditions.Such a grant could change much of the “rules-of-the-game.”

8.3 Estimate of operating costs

These operating costs are generally divided into

fixed costs

and

variable costs

,to allow studies on the effect of different production levels. (See a typicalexample in Table 8.2.) Their estimate is a standard compilation of all thedifferent operating cost categories, that is delivery unit costs and the con-sumption of:



• Raw materials and different materials additives• Services (see below)• Any disposal cost of the waste streams• Any packaging needed and the shipping of the products• The maintenance of the plant, including property taxes• Any contribution to maintenance of the site, taxes to the city, county, etc.• The yearly cost of the plant staff and contractors• Sales expenses, with any duty and taxes (if relevant)• Financial costs, i.e., depreciation and interest on the operating capital• “Miscellaneous” other minor factors

To each significant cost category, a

separate safety margin

(reserve) isadded to reflect the present insufficient state of knowledge on consump-tions and actual delivery costs. These reserves can be added either in theunits needed (i.e., number of kilowatts per hour) or in the unit costs. Theseshould be noted for the record and should be reconsidered in each

futurerevision of the operating cost

estimate, as more reliable information is pro-gressively accumulated.

Contrary to the FCI estimate, the detailed format used for this estimateof operating costs will probably be used later in many revisions, by otherengineers and managers, for repeated economic studies and for routine

Table 8.2

Typical Preliminary Operating Cost Estimate

Fixed Cost per Year Units No. Unit Cost Total

Management / sales employees Man-year 3 80,000 240,000Operation / shift employees Man-year 12 50,000 600,000Other employees Man-year 8 40,000 320,000Overhead on employees Estimate 250,000Indirect taxes and insurances Estimate 100,000Spare parts Estimate 100,000Waste disposal Estimate 50,000R & D Estimate 180,000Total fixed costs per year 2,000,000

Interest on working capital per year 263,000

Variable Costs per Ton of Product

Raw material A Ton 1.51 435 656.85Raw material B Ton 0.916 100 91.60HCl (100% basis) Ton 0.076 35 2.66Lime Ton 0.075 100 7.50Heavy fuel Ton 0.39 35 13.65Water m

3

15 0.32 4.80Electricity Kwatt.h 425 0 25.50Packing and transportation to CIF

Estimate 44.00

Total variable costs 846.56



production budget planning. So it is worthwhile to consider from the begin-ning the most convenient and detailed working format.

8.4 Expected net sales income estimate

The expected net sales income is generally the “weaker point” of thepreliminary economic study, since it has a very large “leverage.” It canonly be estimated, with the active contribution of the market experts andconsultants, from the

expected sales

of product, quantity and invoiced prices,after deducting any possible

expense related directly to sales

, such as thevarious freight expenses to bring the containers from the plant to the finaldestination, agents’ commissions, bank transfer fees, customs duties, andso on.

The confidence level in this estimate could be very different, if:

• The product is intended to be sold in an already established market,with a recorded market

price history

, or within an

exclusive sales con-tract

to a wholesale distributor• The product is relatively new or improved, and its expected sale price

can only be based on what it

should be

worth to users

In addition, the interest on working capital or the cost of the standingcredit at the bank should be estimated, from data on the percent of theproduct in store, in transit or payment delayed as per sales conditions, onthe sales revenue and on the expected level of banking interest. For example,in the above case, 3 months of credit at 7% gives an expense of $262,500 peryear for 100% production.

8.5 Profitability calculation

The expected profitability is calculated following one of several standard meth-ods, which are used in different countries and industrial sectors. This profit-ability is generally expressed as the percent of

return on investment

(ROI), beforeany taxes on corporate income or profits, or as the

present value

of the operationof the implemented project over a period of time, for example 10 years.

Table 8.3 gives an example of the presentation preferred by this author,at this stage of the project review. It includes:

• A

project cash flow

for a period of 12 years, in which the first 2 yearsare for construction and the following 10 years for production atincreasing rates. For example, 50% of the nominal production in thethird (start-up) year, 75% in the fourth (consolidation) year, 100% forthe next 5 years, then a slight but gradual increase of production to110%. (Note that this last assumption has almost no financial conse-quence in a healthy project; it is only included as an expression ofconfidence in the future.)



Table 8.3

Typical Return On Investment — Based on Cash Flow and on Present Value of Yearly Cash Flow (in $1,000)

Total Investment 16,770Average Sales $/Ton CIF 3000 Pecent of Design Production 100Return on Investment 31.1%

Year 1 2 3 4 5 6 7 8 9 10 11 12

Fixed Capital Investment (6,708) (9,224) (839)FC Investment grant Production % of Design

Capacity 50 75 100 100 100 100 100 105 107 110

Total production sale value, CIF 7,500 11,250 15,000 15,000 15,000 15,000 15,000 15,750 16,050 16,500Fixed Production expenses (300) (1,000) (2,000) (2,000) (2,000) (2,000) (2,000) (2,000) (2,000) (2,000) (2,000) (2,000)Variable production expenses (2,141) (3,211) (4,281) (4,281) (4,281) (4,281) (4,281) (4,495) (4,581) (4,709)Interest on Working Capital (131) (197) (263) (263) (263) (263) (263) (276) (281) (289)RoyaltiesNet Cash Flow (7,008) (10,224) 2,390 5,842 8,457 8,457 8,457 8,457 8,457 8,979 9,188 9,502Disc. Net Cash Flow PV (10%

rate) (7,008) (9,294) 1,975 4,389 5,776 5,251 4,773 4,340 3,945 3,808 3,543 3,330

project's present value at 10% ROI

24,828

Disc. Net Cash Flow PV (ROI rate)

(7,008) (7,798) 1,390 2,593 2,863 2,184 1,666 1,270 969 785 613 483

Cum Disc. Net Cash Flow PV 9

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• The projected

capital investment

is divided according to a reasonablepattern, such as 40%, 55%, and 5% in years 1, 2, and 3, unless thereis a specific reason to differ. Any expected FCI grant is deducted.

• The average

net sales return

per ton is taken as constant, for lack ofmore information.

• The calculated

fixed production expenses

(see above) start in year 1 as15% of the average, and 50% in year 2.

• The calculated

variable production expenses

(see above) are assumed tobe proportional to the production.

•

Royalty

payments are generally not relevant at this stage, but inter-ested parties could use this format in their eventual negotiation, tosee the impact of various royalty payments on the profitability. Thiscan be either a yearly fixed sum, a percentage of the net sales, or apercentage of the profits according to some formula.

• The

net cash flow

(negative or positive) is calculated for each year. Ifit is discounted at 10% (say, as a “normal safe” investment), the

presentvalue of the project

is obtained from the sum at year 1, which representsthe

potential contribution

of the new proposal/know-how (nearly $25million in Table 8.3).

• In addition, a

discount rate

can be calculated by simple trial-and-error,which results in present value = zero. This is in fact the

ROI

(31.1%in Table 8.3).

Once prepared, this spreadsheet can be used easily to survey the effectof various factors on either the ROI or the present value of the operation,such as for instance, different values of FCI, net sales returns, raw materialscost, and so on.

Different corporations use different standards to judge the attractivenessof new process proposals, according to their

prevailing strategy

considerations.As a

general order of magnitude

, however, we can say that in the free economyof the Western world, the profitability test at this stage should probably showan ROI of, at least, 25% before taxes, to justify the continuation of an intensivedevelopment and implementation effort. But if this development opens new,promising avenues to the corporation, it could well be that a lower ROI wouldbe accepted for the first plant (see also Sections 8.6 and 8.7 below).

Of course, the degree of taxation varies in different locations and situa-tions. Certain countries promote the establishment of new industries byproviding them with an investment grant (say, as a fixed percentage) or witha period of reduced (or no) income-tax payment.

8.6 Optimistic evaluation of the profit potential in other applications

Together with the profitability study, the promoters could also develop andpresent to the decision makers the possibility that the proposed process mayhave a

larger potential for profitable applications

, once the first implementation



is proven to be successful. Such larger profit potential can be in one or moreof the following forms:

1. The simplest formula is

increased production volume

at the same sitein the future. This extra product can be obtained practically withthe same management and services, by making use of the built-inoversized facility and of the experience gained by the operatingstaff, and could be sold in developing markets. Thus, instead of theusual cash flow and profitability spreadsheet based on the presentnominal capacity for 10 years, an alternative spreadsheet could beprepared in which the production would be increased by 10% (forexample) every 2 to 3 years and the span increased over 15 years,reaching 150%. This is a frequently used format. Table 8.4 illustratesthis change with regard to Table 8.3 above. It can be seen that onthis basis, the project’s net present value at 10% discount rate in-creased from $25 to $46 million. Note that the increase in ROI isnot as spectacular, only from 31.1% to 32.8%. This is typical of thecases with quite high ROI, where the contributions of the later yearsare felt less and less. For another case with an ROI of 15%, thisincreased production could have raised the resulting ROI to 25%,and this change would have made a different impact.

2. Another commonly considered possibility involves future “repeat”plants built in other locations or countries, on the basis of the expe-rience learned in the first plant.

3. A more complex possibility is the adaptation of the novel processtechnology to the production or improvement of (a line of) similarnew products.

The presentation of such potential applications could change the per-spective of the decision makers from short-term cash flow into a widercorporate strategy. Of course, the access and exclusivity of these optionswould need to be secured by adequate patents.

8.7 Possible synergetic effects with other production facilities

In many cases, the promoters may also gain the goodwill of the decisionmakers by pointing out synergetic (that is, mutually profitable) effectsbetween the proposed project and some other existing or planned industrialfacility of the corporation. For example, the proposed project may:

1. Use or upgrade the value of a by-product or waste stream. For example,the recovery and profitable use of valuable acids from a waste stream,instead of neutralizing them, or the utilization of excess concentratedthermal energy, instead of dispersing it into the surroundings.



Table 8.4

Typical Return On Investment with increased production volume and on Present Value of yearly Cash Flow based on Cash Flow

Total investment 16,770Average sales $ /

ton CIF3000

% of design production

100

Return on investment

32.77%

Year 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Fixed Capital Investment

(6,708) (9,224) (839)

F C Investment grant ( 20% )

Production % of Design Capacity

50 75 100 100 110 110 120 120 120 130 130 140 140 150 150

Total production sale value, CIF

7,500 11,250 15,000 15,000 16,500 16,500 18,000 18,000 18,000 19,500 19,500 21,000 21,000 22,500 22,500

Fixed Production expenses

(300) (1,000) (2,000) (2,000) (2,000) (2,000) (2,000) (2,000) (2,000) (2,000) (2,000) (2,000) (2,000) (2,000) (2,000) (2,000) (2,000)

Variable production expenses

(2,141) (3,211) (4,281) (4,281) (4,709) (4,709) (5,137) (5,137) (5,137) (5,565) (5,565) (5,993) (5,993) (6,422) (6,422)

Interest on Working Capital

(131) (197) (263) (263) (289) (289) (315) (315) (315) (341) (341) (368) (368) (394) (394)

RoyaltiesNet Cash Flow (7,008) (10,224) 2,390 5,842 8,457 8,457 9,502 9,502 10,548 10,548 10,548 11,593 11,593 12,639 12,639 13,685 13,685Disc. Net Cash

Flow PV (10% rate)

(7,008) (9,294) 1,975 4,389 5,776 5,251 5,364 4,876 4,921 4,473 4,067 4,063 3,694 3,661 3,328 3,276 2,978

project's present value at 10% ROI

45,791

Disc. Net Cash Flow PV (ROI rate)

(7,008) (7,700) 1,356 2,496 2,721 2,050 1,735 1,307 1,092 823 620 513 386 317 239 195 147

Cum Disc. Net Cash Flow PV

4

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2. Make use of idle production capacity in certain operations, in pack-aging or in utilities generation, or exploit the significant cost advan-tage of larger installations.

3. Utilize available developed land, roads, warehouses, and similarfacilities.

4. Participate in a combined marketing effort aimed at the same users,for example in the compound fertilizers market.

Such interactions would involve the management of the existing oper-ation and, obviously, their essential cooperation and good will should besecured by the promoters before the above claims are presented to a largeraudience.

8.8 Comprehensive report for the justification of the specific proposal

The expected profitability is the “bottom line” of a comprehensive reportpresented to the relevant corporate management for a detailed and exhaus-tive review leading to a “no/maybe” decision, which should include, withan

executive summary

:

• The preliminary process design detailed in Chapter 7• The economic estimates listed above in this chapter• The profit potential for other applications, described in Section 8.6 • Some possible synergetic effects, described in Section 8.7

Many proposed projects have met their end at this stage (“NO”), as thecalculated profitability level was considered, in the eyes of the decisionmakers, definitely not good enough and with no reasonable prospects ofimprovement.

If the profitability potential does look promising (“MAYBE”), a go-aheadwill be given for the next stage of the development program, as discussedin the next chapter. In this case, the above preliminary economic study willbe also used to emphasize those cost items that are “really heavy,” for whichimprovements during the development program could result in a significantpositive effect.

8.9 Contractual agreements

Any authorization given by the corporate management for the next stage ofdevelopment will probably be conditional on the finalization of two contrac-tual agreements.

First, relationships between the inventors/promoters and the imple-menting corporation need to be finalized at this point by a formal contract.Prior to this, an exclusive option agreement may have been signed for a



limited period, conditional on the decision by the corporation to build aplant, by a certain date. The details to be included in such a contract dependvery much on the particular situation and cannot be discussed here, but thebasic interests of each party are clear:

• The inventors/promoters really want the project to succeed, andthey generally believe that they can contribute to that success byhaving a say in any major decision making in future. They alsowant clear public recognition and, of course, the maximum finan-cial remuneration possible, in relation to their optimistic profitpotential.

• The implementing corporation wants to secure the full cooperationand contributions of the inventors/promoters in the future, includingthe assignment of (present and future) patents, exclusivity on theirpast know-how and on their future work in this field for many years.The corporation would like all this, of course, at a minimum costwithout conceding any part of its decision-making position. To assurethat position, the financial remuneration may be divided into pro-gressive installments.

Once this contract is signed, the overall responsibility of the workingprogram will be transferred to the project manager appointed by the cor-poration. The inventors/promoters will generally continue their contribu-tion as consultants.

Second, a suitable engineering company should be selected andengaged by a service contract that, although quite standard in nature,always includes many specific clauses (see also Chapter 10, Section 10.5).The engineering company will provide many of the professionals neededfor the working program, mostly from their permanent offices, but someof them may also be delegated to the project manager ’s team or to thedifferent pilot sites.

The project manager will likely chose the engineering company basedon past experience and will generally include, as a basic condition, a list ofeight to ten key leaders, employees of the engineering company, who willbe assigned to work most of their time on the project.


• The only purpose of the preliminary economic analysis of the pro-posal is to supply information on the profit potential and to justifythe continued expense for its development.

• The presentation of a larger potential of profitable applications, oncethe first implementation is proven to be successful, could change theviewpoint of the decision makers from the short-term cash flow to awider corporate strategy.



References

1. Peters, M. S. and Timmerhaus, K.,

Plant Design and Economics for ChemicalEngineers, 4th ed

., McGraw-Hill, New York, 1990.2. Chauvet, A., Leprince, P., Barthel, Y., Raimbault, C., and Arlie, J. P.,

Manualof Economic Analysis of Chemical Processes

, McGraw-Hill, New York, 1981.



chapter 9

Working program toward a first implementation

Following approval by corporate management to proceed on the basis of thepreliminary process design and economic estimate (the “green light,” seeChapter 8, Section 8.8), the work program will expand considerably and willrequire a larger number of professionals, organized in several differentgroups and possibly in different locations. The core team, which will workwith the project manager at the center of the campaign, will also have to beconsolidated at this point.

This chapter deals with those parts of the working program that can bedone in parallel and handled as “separate jobs,” with proper directives,under the direct coordination of the project manager. Chapter 10 will beconcerned with the consolidation of all the results from these different jobsinto a single, final plant design.

9.1 Patent protection

9.1.1 Revised or additional applications

Following the experimental program and further conceptual shaping in thepreliminary process design, one should ask: “if we knew at the time of thefirst application what we know at this present stage, how would we formu-late the patent’s claims?”

In many cases, analysis of the results from the experimental programmay point out specific features, or particular ranges of variables, that appearat this stage to be clearly essential for successful and profitable implemen-tation, which were not obvious from the start, even “to a person versed inthe art” (in the patent’s archaic jargon). The patent should therefore bereviewed in order to determine if any of the claims included in the firstapplication should be changed, or new claims added. The senior project staffwill now examine with the patent experts whether:



• Such

specific novel aspects

can be presented convincingly as

discov-eries that are essential

to practical industrial implementation and,if so,

• What is the

best procedure and timing

for preparing and submittingrevised or additional applications to cover these specific novelaspects?

Separate applications are often recommended to increase the legal protectionfrom different angles, but these additional applications also require invest-ment of time and some significant expense (see below).

The conclusions of this review should probably also be relevant withinthe terms of the contractual agreement between the inventors/promotersand the implementing corporation (see Chapter 8, Section 8.9). These gen-erally define the nature and extent of the intellectual rights for whichexclusive licensing should be provided in the contract, including any patentassigned by the inventors to the corporation, and (most important!) theoption for the corporation to award recognition for substantial contribu-tions, by adding other “names” to the list of inventors, in the revised oradditional applications.

9.1.2 Extended geographical coverage of the patents

The procedure of the international Patent Cooperation Treaty — PCT —allows a patent applied for in one location, on approval, to be filed in anyone of 70 to 80 different countries with no further examination. However,the extent and locations of additional filing have to be decided within a relatively short time after the PCT approval, and filing in each country cancost up to thousands of dollars in registration, attorneys’ fees, translation,and other similar expenses. This cumulative cost is for every separate appli-cation, so that the decision to file many separate applications in many dif-ferent countries can become very costly.

9.2 Detailed process design

9.2.1 Piping and Instrumentation Diagrams

The process engineering team will now prepare, with the active participationof the engineering company’s staff, “revision 0” of the P&ID drawings. Whenready, these drawings will then be distributed to all members of the projectteam and consultants, for their review and comments. These drawings willbe

revised several times in the future

, as more detailed information and com-ments become available, until they are finalized as “approved for construc-tion.” These P&ID drawings, as can be seen in typical examples in Figures9.1, 9.2, and 9.3, include all major and secondary equipment items, with theirformal names, tag-numbers, and main specifications, as also collected in theequipment list.



• The major equipment items have already been defined and charac-terized in the preliminary process design (see Chapter 7, Section 7.8)and are further discussed in Section 9.3 below.

• The secondary equipment items are those that can be selected fromstandard models found in supplier’s catalogs. This selection or rec-ommendation is generally made by the sales engineers or specialistsfrom suppliers, in response to specification sheets prepared by theengineering company. These equipment items consist mostly ofpumps, fans, compressors, standard heat exchangers, solid handlingequipment (conveyors, elevators), agitators, and so like.

• In addition, in a new process, there may be some equipment items thatcannot be attributed from the start to either group. For instance, aparticular heat exchanger duty could present unusual features (suchas in the flow conditions, in some safety hazards, in the possibility offouling, or in feed-back control) and thus a thorough discussion isneeded with the potential suppliers, before a choice can be made be-tween a standard model or a special modification. Similarly, the choiceof certain pumps can be critical in particular situations, if a “normal”leakage of a process stream could become a safety issue or if solidscould accidentally find their way into the stream. The impeller of anagitator may have to be specially redesigned in order to avoid thecreation of emulsions in certain liquid–liquid mixing operations.

9.2.1.1 Piping lists

These lists include all the piping lines with their standard diameter and“schedule” (wall thickness), material of construction, and tag-numbers. Apiping line is defined and tagged as it connects one piece of equipment toanother. If thermal insulation of the piping line is needed, its thickness isalso noted at this point. The pipe diameters are calculated from the materialbalances tables, including a chosen “reserve,” and from acceptable “linevelocities” (which can be quite arbitrary), and rounded to the next upperstandard diameter (that can also add a significant reserve!).

The routine specification/sizing of piping in a conventional plant designis generally processed automatically by technicians, but for a new processwhere different “unknown” factors could be relevant, the process engineer-ing staff should review these piping specifications carefully and repeatedly.This task may seem trivial, but many of the problems in start-up can gener-ally be traced back to an error-of- judgment in piping specification.

Any change in the piping in an operating plant can be very complicated.Therefore, greater care should be devoted to those “added reserves” for anew process, to allow for the possible increase in some flow-rates during theplant’s start-up, to solve unexpected problems, to arrive at process optimi-zation, and for the eventual increase of production after de-bottlenecking.Note that the added cost to increase the size of small diameter piping isgenerally insignificant.



However, in certain cases, a larger diameter may be counterproductive.For example, in pipes handling streams that may contain solids, a decreasein the stream velocity could induce their settling and accumulation incertain parts.

9.2.1.2 Valves

All the valves needed for different functions are listed and tag-numbered,each with its location, standard, material, and size. The types of functions are:

• “On-off” for complete opening or closing of the flow, leaving the pipeupstream full of the process stream. Is this acceptable process-wise?Not always.

• Throttling to impose a back-pressure and reduce the flow-rate. Dif-ferent types are available for specific stream characteristics, i.e., theexpected degree of erosion. How to choose the best model?

• By-pass: a set of three “on-off” valves that allow the flow to be detouredfrom its normal route, through a particular piece of equipment.

• Drain: on-off valve at the lowest point of a piece of equipment or apipe. Does it open directly into the open air or into a draining pipe?Could solids clog it, and in such cases, would a flush-back washingarrangement be needed? Would there be a hazard if some leakagedid occur?

• Venting: on-off valve at the highest point of a piece of equipment ora pipe. Is it open directly to the atmosphere or into a venting pipe?Would a leakage present a safety hazard?

• Sampling: specially designed on-off valve, to remove samples forinspection or analysis, while avoiding any dead space between therunning stream and the outlet, or providing a flush-back arrangementto arrive at the current material.

• Flushing: certain pipes need flushing with water to prevent accumu-lation of solids.

In a new plant with a novel process, more valves are generally provided

thanfor a conventional process, to allow for more flexibility, for easier inspectionand cleaning (i.e., if solid precipitation could occur), and for the extensivecollection of data during start-up and optimization. This is important inparticular for the flushing and sampling valves.

9.2.1.3 Instruments

All the

instruments for local indication

and for the

control loops

are marked andtagged on the P&ID drawings, then listed according to their expected basicprocess duty. Their functional scope and general policy are agreed withinthe core team, before transmission to the detailed engineering. In this rapidlychanging technological field, the specification sheets and the final choice ofthese instruments have to be done by specialists, updated with the latest



developments, and with the feedback comments from users. This choice isgenerally done in personal meetings between a process engineer and aninstrumentation designer from the engineering company and the sales spe-cialist from the supplier.

In a new plant with a novel process, a much larger number of local instrumentsare installed

to allow for initial calibration, collection and checking of indi-cating data during the optimization stage, together with some degree ofcross-checking on important points. These extra local indicators will beremoved eventually, when the production is stabilized and there is no needfor them anymore.

9.2.1.4 Control loops

Control loops, with their standard definition and control valves, are essen-tial to control flow-rates, liquid levels, stream temperatures, pressures,pH, or other analytical features. The further integration of these controlloops into the computerized control system is discussed further in Section9.6.4 below. The selection of the hardware equipment is similar to theprevious section.

9.2.1.5 Flanged manholes and hand-holes in closed pieces of equipment

These openings are needed in any plant, for inspection and cleaning of theinterior or access to carry out adjustments or modifications, without havingto dismantle the piping and instruments connections or the drive and upperconnections. It is always advantageous to have more of these openings, butthey add significantly to the installation cost, and they can eventually causetrouble, by leaking out process streams or leaking in air.

In a new plant with a novel process, a much larger number of flangedmanholes and hand-holes are generally designed than in a conventionalprocess, to allow for better inspection during start-up and optimization andeventually, for handling of unexpected situations.

9.2.1.6 Provisions for possible future connections

Since changes in the piping of an operating plant are always very compli-cated, it is a good practice to design and provide certain connection points(flanged nozzles in the equipment and flanged “tees” in the piping), so thatpiping additions can be hooked up with only brief interruption. In a newplant with a novel process, a much larger number of such provisions isworthwhile, to allow for more flexibility in optimization and de-bottleneck-ing. Their extra physical cost is very small compared to the possible gains.It is important, however, that their locations be very carefully plannedaccording to likely scenarios.

Another use for these extra nozzles in a new plant with a novel processhas often been to “unplug” solid deposits in certain lines that often appear,sometimes with no clear cause, and have to be dealt with.



9.2.1.7 Non-conventional drives

Non-conventional drives are also marked on these drawings. Although gen-erally, the electric motor drive is not tagged separately but considered aspart of the equipment, certain motors are different. The special process dutyof such drives could be specified as: “variable-speed,” “high-torque,” “withfeed-back control,” or “direct steam turbine,” etc. If certain electrical drivesneed to be connected also to an emergency electrical supply, this is empha-sized on the P&ID drawings and on the lists.

Lists of all equipment items, piping lines, instruments, control loops,and electric drives are prepared in a suitable format (revision 0), in additionto the P&ID drawings. These spreadsheets will be used and revised furtherin all the detailed engineering work.

9.2.2 Examples of portions of piping and instrumentation drawings

The following three typical examples are given to illustrate that certain verysimple process concepts, which are almost taken for granted, can becomequite complicated to design and operate in the plant, and require carefulattention to many details to be applied successfully.

Figure 9.1 illustrates a very simple statement in a process description:“the overflow (stream 6507) from stage 1 is cooled to 45

°

C and transferredto stage 2.” In the plant, this statement translates into three pieces of equip-ment and three control loops, plus pipes and valves and local instruments.Of course, most chemical engineers know this but quite a few process devel-opers have no definite idea of the translation of such a simple statement(“the engineers will take care of that”). This means that the overflow processstream PI-6507 is collected in a buffer tank TK-1054 and pumped by P-1054

Figure 9.1

P&ID example of overflow cooling and transfer duty.

LT06

FEM09

TT08

TC08

TY08

TV08

FV09

FY09

FT09

FC09

LC06

TT07

TI07 1"

2"

2"

TK-1054

3"-N-43678"-V-4320

6'-PI-6507

P-1054

CoolerE-1054

3"-CWS

3"-CWR

3"-PI-6508



through a plate heat exchanger E-1054. The flow is measured by FEM-09and the liquid level in TK-1054 is kept constant at a desired level by LC-06,which cascades on FC-09, which operates the control valve FV-09 on theoutgoing stream to stage 2. The temperature is monitored in TK-1054 by TI-07 and the final cooler temperature is measured and controlled by TC-08,through the control valve TV-08 on the return flow of the cooling watercircuit. Of course, TK-1054 has to be vented and (in this particular process)kept under nitrogen blanketing. A bypass is provided for the process streamaround the plate heat exchanger to be able to continue operation whilemaintenance operations are done in this cooler. Sampling valves and otherstand-by valves are also provided.

Figure 9.2 represents a portion of a P&ID for a process making puredry hydrofluoric acid (HF), by distillation from an intermediate processstream containing HF, water, and a third component (needed to decreasethe vapor pressure of the water). In principle, this is a very simple strip-per/rectification column, with a reboiler, a condenser, and condensatereflux, and extensive physical data has been published on this system. Thebottom stream is recycled to the process backwards. But in fact, there arequite a few complications that require experienced decisions. First, theatmospheric boiling point of HF is about 20

°

C. Operating the condenser

Figure 9.2

P&ID example of a distillation section for dry HF.

P-101

P-102 P-103

TK-105

E-102

Refrig.systemHS-101

freon vapors

freonliquid

reflux

HF vapors

bottom to recycle

CWR

CWS

M

mixedsolution

HPS

D-101

to vent

to vent

to vent

productstorage

fromto

PI

LT LIC

TE

TRC

PCV

E-101

TE TRC

TE

TRC

TI

PIPI

TI

PC

PI



with cooling water would require maintaining the whole system underpressure and raising the temperature in the reboiler, thus requiring a veryhigh steam pressure and mostly very expensive materials of construction.This was ruled out and an operating pressure around atmospheric wasopted for; therefore, the condenser was designed with a

dedicated mechanicalrefrigeration unit

. The column is operated with a temperature gradient; itsupper section is kept quite cool by the reflux of cold HF, which serves alsoas a direct contact cooling medium, as a large part of the reflux is justevaporated and returned to the condenser. This means that the columncannot be operated, or

even started

, without a significant amount of reflux,and therefore

a stock of HF must always be kept in the receiver TK-105

to bridgetemporary interruptions in operation. After longer stoppages, HF may haveto be brought back from the product tank into TK-105 to restart this unit.

The ultimate irony is that this plant cannot be started for the first time withoutbuying some product from the competition!

Of course, the whole unit must beclose-vented and all the noncondensable gases sent back to the scrubbersoperating in another section of the plant. Thus the amount of instrumen-tation and control shown in Figure 9.2 is in fact only the starting minimumfor review, and careful designers may decide to add more means of oper-ational flexibility and safety. These problems are typical in many cases ofnew process design and development.

Figure 9.3 illustrates some typical complications that have to be takeninto account in the P&ID for such a simple operation like a thermal evapo-rator for large-scale preconcentration of a relatively diluted aqueous solutiongoing to crystallization. Significant amounts of water have to be evaporatedat the lowest cost. Mechanical recompression is generally one of the bestchoices in connection with a falling-film evaporator operating under vac-uum, which seems to be simple enough and there would be a number ofspecialized suppliers always eager to make an offer. In principle, the solutionis circulated and distributed as a film on the inner wall of the vertical tubes;it falls down while it is heated by the condensing steam in the chest outsidethe tubes; part of the water is evaporated, separated in a side vessel. Afterthat, the water vapors are compressed and sent into the chest. A centrifugalcompressor is generally the best choice for such duty (compression ratio),energy-wise. But such a compressor is very sensitive to the presence of solidparticles, or even liquid drops in the vapor, considering the very high shear-ing forces. Thus the vapors from the evaporation have to pass through aseries of treatments:

1. Separation from the main concentrated liquid, which may be froth-ing, into a side vessel.

2. Passed through a mesh entrainment separator, equipped with a peri-odical washing system, actuated by a differential pressure controller.

3. Mixed with recycled hotter vapors to “dry” any possible microscopicdroplets remaining, before entering the compressor. This recycle isset by a down-stream temperature controller.



4. After the compressor, the vapors are desuperheated by a spray ofcondensate water in excess, since for a change, such excess is notdetrimental.

5. Then, the make-up stream of low-pressure steam is mixed in. Therecould be different control schemes, according to the characteristicsof the system and the quality of the thermal insulation. The mixedvapors are distributed in the chest and flow downwards while con-densing on the tubes.

6. The chest is a closed vessel and any noncondensable gases presentwould accumulate and prevent further condensation. Thus thesegases have to be continuously removed by a side-vacuum system,under the control of a pressure-control system. The standard vacuumsystem requires a direct condenser stage, discharging through a“barometric leg” or “hot well” and a water-ring vacuum pump witha cold water stream.

Figure 9.3

P&ID example of a falling-film, vapor-recompression evaporator.

M

M

M

condensatefeed

hot well

coldwater

vacuum pump

condensate

concent.soln.

CW

DC

TI

TI

TI

TI

TIC

PE

PIC

PDI

compress.

LC

LIC

FR

LP steammakeup

TE

TI

PI

LE

LELE



7. The amount of noncondensable gases in a system under vacuumdepends mostly on leaks inward of air, due to faulty installation ormaintenance, and many plants experience difficulty as a result. Thus,an oversized vacuum system could help in many cases.

One can therefore see that the smooth operation of such a conceptuallysimple evaporator can depend on many detailed issues requiring decisions,and the developers cannot just relegate these details to the expertise of thesuppliers. Instead, they should at least understand exactly what is involvedin the new process. We have not discussed proprietary technology that everysupplier is claiming for himself such as, for instance, the exact distributionof the liquid films inside the tubes, the eventual cleaning of these tubes,various internal baffles and vapor routes, etc.

9.3 “Major” equipment packages

Major equipment packages are groups of equipment items that are pivotalin the plant and should be designed or procured together, in process-com-patible materials. These packages could be, for instance, a multiple-effectsevaporator, a distillation section, a crystallization system, or a mixers-settlersbattery for solvent extraction.

The preliminary process design gave a

functional analysis of the processrequirements

for this equipment package, as quantified in the material andheat balances, with a draft specification sheet and a list of potential suppliers(see Chapter 7, Section 7.8). Some of these suppliers have already beencontacted for the FCI estimate. At this stage, more extensive discussionsshould be conducted by the senior process team with each of these suppliers,preferably in face-to-face meetings, if this is possible, to explain the particularneeds of this project and to clarify the following aspects:

• Which possible design options would these suppliers consider forthis particular case and what is their preference? Each option will bedetailed, with advantages and disadvantages.

• What is the extent of their previous experience on similar projects?Are they willing to disclose details and allow direct contact withreferences?

• Who are their designing experts and what is their theoretical back-ground, in particular for designing a first-plant case?

• What process data is absolutely needed for their design?• Do they have the piloting equipment and the staff to run the necessary

demonstration and optimization tests, which could be used in thisproject at their place or which could be shipped to another pilot site?

When these open discussions reach a more detailed stage, a mutuallybinding secrecy agreement will probably have to be signed. A good procedurewith suppliers is to cross-check their claims with independent consultants.



After the first round of discussions, a preferred supplier will usuallyemerge for each major equipment package, on the basis of the confidence,the cooperation and the facilities that they can provide. For a

critical

majorequipment package, the actual purchase cost is probably a secondary con-sideration of the project team, as long as it remains in the reasonable range(

although this fact of life will never be admitted openly!).

The proposed equipmentdescription and the numerical data obtained from this supplier will be usedto proceed with the engineering work at this stage. However, to maintainthe formal procedures and to retain a fallback option (in any case), thispreferred supplier will be generally included in a short-list of two or threeother possibilities, which will be maintained fully in the picture until thefinal bid is allocated. Such “rules-of-the-game” are generally well known toeveryone concerned in this field!

Apart from the “packages,” the configuration of some other majorequipment may have to be

specially developed (or more exactly modified)

anddesigned to obtain the particular performance duty that is specified forthe new process. The eventual cooperation of a specialized supplier, whois “close enough” to the desired technology, could be advantageous butit could also raise delicate issues concerning the future exclusivity andownership of this new know-how, once the actual plant results becomeavailable.

9.4 Pilot testing of specific process operations

Pilot testing of some process operations may be required to confirm detailedquantitative specifications for particular pieces of equipment items, whenthese operate with the exact streams of the new process. Examples are givenbelow.

9.4.1 Multiple-effects evaporator

The

basic design

of a multiple-effects evaporator for budgeting purposescould be based on bench-scale equilibrium data, but the reliable

detaileddesign

of an industrial installation will require the

experimental

determina-tion of certain quantitative factors that could be still unknown, such as,for instance:

• What heat transfer coefficient can be obtained with different concen-trations of the solution (density, viscosity) and with different veloc-ities in the tubes, and what will remain from the heat exchanger’sperformance after a few hundred hours of operation and the resultingdeposits (coating) on the heat exchange surface?

• What would be the possible effect of any noncondensable gases orsoluble impurities dissolved in the feed solution on the behavior ofthe solution boiling inside, such as frothing, splashing, precipitation,and possible encrustation of solids?



• What would be the frequency, method, and ease of internal cleaningand how would that affect the average number of working hoursfor design?

• What would be the “external” behavior of the concentrated solution,once it is removed from the evaporation conditions (depressuriza-tion, cooling)?

Furthermore, larger quantities of concentrated solution may be required fortesting of the downstream operations relative to this evaporator, such as acrystallizer, a flaker, a spray-dryer, and so on.

These requirements necessitate the

continuous operation of a pilot evapora-tor

, equipped with all the instrumentation for collecting the necessary data,while storing the resulting concentrated solution in suitable containers. Thetest period would be relatively long (a few weeks, for example) and sufficientquantities of the starting solution needed, of the actual composition or asclose as possible (with due reservations). Such piloting can be done in aspecialized R&D institute, or in cooperation with a potential equipmentsupplier, who could rent a portable pilot installation and operate it.

9.4.2 Liquid–liquid contacting battery

Another example of a major package is a “multiple-stage, counter-current,liquid-liquid contacting battery” for a solvent-extraction process. For design-ing a “horizontal” battery of mixers–settlers, in which each stage is assumedto be practically at equilibrium, all the process aspects can be calculatedreliably from the results of bench-scale equilibrium tests, such as the numberof theoretical stages, the concentrations, the mass transfer rate in a mixedvessel, and the liquid–liquid separation rate (see Chapter 6, Sections 6.2.3and 6.4.1). This choice of equipment was therefore popular for implementa-tion of new processes (Chapter 4, Reference 13) and it would probably stillbe the best choice for a small number of stages (say three to five).

However, when a larger number of stages is required, with larger flow-rates and more costly solvents, the option of a mixers–settlers battery couldpresent significant disadvantages as compared to a continuous vertical col-umn-contactor, or to a set of centrifugal extractors. These disadvantagescould be, for example, a bigger internal inventory of solvent, a larger hori-zontal area in the plant’s layout, the need for more intermediate pumps, andso on. These issues have been discussed extensively in international confer-ences and some recent papers relevant for industrial equipment are listed inthe references.

11–14

Cusack et al.

11

presented the development of a new highcapacity column design from an analysis of previous models (Koch). Axialmixing in large-scale packed extractors is detailed in Reference 12. Lo

13

reported on an experimental comparison among three different existingmodels of columns, his conclusions for one particular case and the scale-upprocedures to be used for an industrial project. Movsowitz et al.

14

reportedon a rather exceptional case in which a uranium plant in Australia worked



for two years in two parallel lines, one with four mixers-settlers and thesecond with two Bateman columns and then it was decided to use (of course)more columns for their new expanded plant.

Several suppliers offer vertical columns/contactors, each with their ownproprietary design and know-how. None of these columns can be reliablysized without

extensive pilot testing for each case

with the

actual materials

, inorder to determine: acceptable velocities, height of a theoretical contact stage,behavior of the phases mixture (observations), starting procedure until asteady-state operation is reached, and so on. Therefore, each supplier isorganized with its own portable pilot installation and expert staff, which canbe hired by a prospective client to conduct such tests with his own materials,for process demonstration and equipment sizing. In many cases, the hiringfee for the pilot is deducted from the purchase price of the industrial equip-ment, if a deal is reached.

But for the process engineering group, the main issue before orderingsuch equipment for a novel process is to understand the internal mecha-nisms, which are generally not entirely published. For example, how theperformance is scaled-up and

what can be modified

if the results obtainedduring start-up are unsatisfactory?

9.4.3 Main problems for piloting

The above typical examples emphasize the two main problems related tothe piloting of specific process operations, from the point of view of theimplementing corporation:

• The investment in a new, owned pilot would be expensive, requirein-house expertise and a relatively long time to start and, therefore,would be justified only for a long-term continuing R&D program inthis particular field. Otherwise, after the conclusion of these series oftests, this pilot installation could remain unused for a long time. Onthe other hand, these pilot tests could be possibly done in cooperationof a pre-selected supplier, as most suppliers of specialized equipmenthave their own pilot installations. However, such preselection couldimpose many formal limitations, which should be clear and accept-able from the beginning.

• The procurement of a sufficient quantity of representative feed solu-tion may be difficult and may need to be produced in another pilot,according to the upstream operations (before the one under consid-eration). This condition may require a more comprehensive andlengthy program.

9.5 Modeling

The methodology and technique for the development of a dynamic mathe-matical model that can simulate a specific process have been occupying the



attention of the chemical engineering scientific community for the last twoor three decades, and have evolved rapidly with the advancement of com-puterized resources. This is one of the most popular (fashionable?) academicfields in chemical engineering faculties and many commercial programs arealso offered to the professionals. There are good textbooks and publicationsand there is therefore no need to recapitulate them here.

1–4

However, any such model can only be as good and accurate as the numer-

ical data in its data base and this weak point has discouraged many developersof novel processes. It is therefore important to recognize the importance andthe need for such a tool, by considering it a

long-term investment in the processdevelopment program

. Thus, the model can be started and run first on the basisof “reasonable assumptions” and the significance of the results can be studiedand understood. Then, after the first runs, a list should be prepared of certaindata with significant leverage, which should preferably be confirmed andcompleted by additional bench-scale tests (see Section 9.6.3 below). The modelwill therefore be

progressively improved

.A dynamic mathematical model, as the quantitative basis of this specific

process, will be used first for the important, but not critical, task of theengineering design of the instrumentation and control systems and for deci-sions concerning the volumes of buffer tanks. (This design is not criticalbecause it is dealing with relatively wide ranges.) However, at a later stageof the plant’s design (see Chapter 10, Section 10.2), this dynamic mathemat-ical model should be used for a

critical task

, in order to

evaluate the conse-quences of any change

in: the composition of the raw materials, the concen-tration of possible impurities, the kinetics of mass transfer, or the qualityrequirements from the new products.

Finally, after the plant’s start-up, this model should be expanded tocorrelate and interpolate the operating plant’s results. This expansion willhopefully culminate in the achievement of new process know-how for thedeveloping corporation.

9.6 Complementary bench-scale testing program

Following the experimental work described in Chapter 6, which served asa basis for the preliminary process design described in Chapter 7, specificadditional experimental work will generally be needed to generate somespecific and important missing data.

This complementary program of

bench-scale tests

can probably be donein the same R&D laboratories that were used before, in parallel with theother tasks discussed in this chapter. It can be divided, according to theirlevel of urgency for the overall effort of this working program, into sevendifferent tasks to obtain additional data needed for:

• Detailed specification of the industrial equipment• Design of pilot installations or interpretation of their results• Process modeling



• Design of instrumentation• The final choice of materials of construction (“corrosion”)• Clarification of waste disposal issues• Clarification of process safety issues

9.6.1 Detailed specification of the industrial equipment

Following consultations with the equipment suppliers, a detailed list willemerge of all the specific factors that may have a significant effect on thechoice, sizing, design or expected performance of the different items of majorequipment (see Section 9.3 above).

A fact of life common to almost all projects is that, from the moment oftheir request, the availability of these quantitative results becomes an urgentrequirement for the continuation of effective engineering work, either by thecontractors participating in the bids, or by the engineering company. (Thisurgency will be strongly and repeatedly emphasized by the engineers.)Examples of quantitative data that may be required are:

• Simple physical properties, such as the density or the viscosity of aparticular stream, at a specific composition and temperature. Lessfrequently, more complex physical properties may be needed, suchas the wetting contact angle between different phases, thermal con-ductivity, dielectric coefficient and other electrical properties, opticalcharacteristics, and so on.

• The density, size distribution, and characteristic shape of resultingsolids (i.e., crushed rock or crystals produced), which could affectthe bulk density of a loosely packed bed of such solids in a silo, ortheir transfer by pneumatic conveying. In addition, the shape andsize of these particles can affect their flow properties (“bridging”)and their rate of dissolution or of settling.

• The reaction rate and/or the mass transfer rates of certain reactions,under specific driving forces and in specific contact conditions, such asthe mixing regime, differential velocity, temperature and pressure, etc.

• The ion-exchange rate with specific commercial resins and processstreams, in certain flow conditions.

• The results from standardized technological tests, such as the grind-ing rate of solids, the settling rate or the filtration rate of a slurry, thecompaction of a powder under pressure, etc.

9.6.2 Pilot installations

As discussed in Section 9.4 above, pilot-plant installations can be very expen-sive and lengthy operations, and they can “get stuck” if they are not properlydesigned to cover the specific function of the novel process. However, a pilotmust obviously be designed without having all the necessary information.It may be worthwhile, therefore, to increase its chances of success by getting



some of this information from rapid bench-scale testing, if possible beforecompleting the design of the critical parts of the pilot (for example, thereaction rate curve in a mixed reactor). These bench-scale tests suddenlybecome of the highest priority on the critical path of the whole project.

9.6.3 Process modeling

As discussed in Section 9.5 above (and later in Chapter 10, Section 10.2), themethodology and technique for the development of a dynamic mathematicalmodel, simulating the specific process under consideration, require

accuratenumerical data

at its data base. Most of this data could probably be obtainedfrom textbook “laws,” published scientific information, or previous test workdone on this subject or on similar projects. However, some

assumptions

areprobably also needed to close the cycle and start the model running.

Thus, after the first few runs that are needed to get a good feeling of thesystem, certain “insecure”

cause-to-effect

data with significant

leverage

can bedefined. For instance, the cause could be a change in temperature, or a changein concentration of a certain variable that could be caused by dilution, or bythe ineffective dispersion of an added reactant stream. The related effectcould be in the rate of precipitation, in the level of supersaturation, or in thesolubility concentration. Obviously, in any real process, the number of suchtheoretical cause-to-effect relations could be enormous “on paper,” but for-tunately, only a relatively small number of these relations would generallyhave the kind of leverage to justify their inclusion in the dynamic model,and these relations should be carefully selected and defined, in the limitedrange of practical interest.

Therefore, additional bench-scale tests should be arranged to confirmand complete the data needed on these selected relations. Such tests couldprobably be combined with those described above in Section 9.6.1, since theyare of the same general type.

9.6.4 The design of instrumentation

The choice of instrumentation hardware for chemical plants, from standardcatalogue items, can be critical. Most of the modern instruments are basedon

physical characteristics

of the stream under surveillance, such as its elec-trical conductance or capacitance, its magnetic density, and its optical prop-erties under various wavelengths. Entrained impurities in the actual processstream, or even simple dissolved components such as water or atmosphericgases, may affect some of these physical properties.

Fortunately, the specialized companies supplying such hardware havetheir own extensive data bases and their instruments cover wide ranges sothat, in most cases, they are able to complete their recommendations andoffers on the basis of the nominal analyses of the streams concerned, withthe reservation that their final calibration needs to be done during the plant’sstart-up. However, there may also be some reservation when a new process



is considered and their guarantee conditional on certain

assumed

values ofthese characteristics. These companies will probably recommend performingspecial tests to supply such information or perhaps delivering representativesamples for testing in their laboratories.

9.6.5 Corrosion tests

The tests needed to confirm the choice of materials of construction werediscussed above in Chapter 3, with respect to any unknown corrosion effecton the materials of construction used for the equipment and piping. This isimportant first for establishing safety measures to prevent accidental failure,but also for estimating the lifetime of each piece of equipment, its supplycost and maintenance schedule, or the possible contamination of the productwith metallic traces.

The orderly testing of the corrosion rate is a long procedure that was(hopefully) started at the beginning of the process development, for eachcombination of the most probable construction materials and some typicalsets of process conditions. An expert consultant with relevant industrialexperience was probably engaged at that time to recommend options andprocedures to arrive in time at the optimum specifications for materials ofconstruction.

But at that time, the exact process conditions for corrosion testing (com-positions, chemical additions, or temperatures) were not available. Now,since the confirmation of the final choice has to be included in the purchasingspecification of the equipment and the matter is again on the critical path ofthe project, additional tests may have to be done very urgently with the finalmaterials and conditions.

Furthermore, the public authorities and the insurance company repre-sentatives may insist on receiving written certification from an expert, atleast in relation to the risks and damages that may result from a possibleaccidental failure.

9.6.6 Clarification of waste disposal issues

The definition and quantification of all the possible waste streams andoptions for their disposal within the framework of the particular regionconsidered, are critical features of any new chemical implementation. Thisspecialized field of activity includes various technical, commercial, and legalaspects. During the new process development stages, at least one acceptableand affordable disposal procedure has been defined for each waste streamand included in the project’s scope. But now, this proposed disposal proce-dure should be presented to the relevant authorities, with all the supportingdata to obtain their formal authorization.

Urgent tests may now be performed to produce any additional data thatmay still be needed for the final design of the treatment operation and theconvincing evidence of the results. These tests are generally of a specialized



nature and may have to be subcontracted to a suitable laboratory or to aninstitution with the relevant experience. For example, in one case, it wasintended that most of the organic waste stream would be incorporated intoa commercial cattle-feed mixture and thus had to meet certain specifications.In another case, the solid residue was intended to be integrated into abuilding-blocks production line and had different requirements. In stillanother case, the residue of microorganisms from a fermentation processwas found to have a very beneficial effect on the operation of a municipalsanitary-waste bio-sludge installation. Each case is different and there aremany problematic situations.

9.6.7 Clarifying process safety issues

Most chemical plants could present some form of known safety hazard,which has to be kept well under control. (See Chapter 3.) The implementationof a novel industrial chemical process can introduce an unknown safetyhazard, unfamiliar to the corporation and not taken into account in itsoperating practice. A systematic survey and consultations with a safetyexpert should have been started early enough in the development programto identify such potential safety issues, and to document them in detail, indifferent safety manuals, for the lab, pilot operation, and plant. Relevantpublic regulations in the area of implementation should also have beensurveyed, and this information included in the plant’s design and control,with the necessary requirements to ensure safe operation, to the best of theproject manager’s judgment.

Now, with the finalization of plant design and the application for thenecessary permits, certain

standard

laboratory tests may still be needed (pos-sibly from a statutory organization such as a standards institute) to

certify

certain key issues, such as for example, the flash-point for a particular mix-ture of organic solvents, or the handling of a certain radioactive or poisonousimpurity present in any of the raw materials or fuels, which should bemonitored and kept under surveillance.

9.7 Preparation of product samples for market field tests

The marketing experts of the corporation generally conduct these fieldtests, either directly or through their regular geographical distributionchannels, while the plant is being designed. The usual procedure is tocontact a number of randomly chosen end users, show them the samples,the analyses, and the specification of the expected products, and ask fortheir comments.

The feedback from such contacts should be available as soon as possible,as it could be very important for:

• Confirmation of the final form designed for the products• Specification of any change needed



• Confirmation of the estimated sales revenue from the products

But this simple standard procedure can only start when significant quan-tities of representative samples of the products are made available, of theorder of tens of kilograms. Thus, an important but difficult task, at thisstage of the working program, is to prepare rapidly such representativesample products, without a “production line.” This problem should beemphasized to the whole team, as creative thinking and past experienceare often needed, for example, to:

• Integrate as much as possible of such production into the piloting orthe testing programs mentioned above, such as the crystallization,evaporation, and liquid–liquid extraction.

• Improvise practical batch or manual methods, with any availableequipment, to prepare large quantities of starting material and tobridge over the missing intermediate operations, such as acid leach-ing, filtration, centrifugation, solid drying, and screening.

9.8 Clarification concerning any formal permits needed

Any new plant projected will require, most probably, a number of formalpermits from different public authorities, as well as comprehensive insurancepolicies. These permits differ from country to country, but they are concernedwith different aspects of:

• The plant’s construction, in relation to possible adjoining operations,local building planning, residences, roads, etc.

• The plant’s operation, in particular the transportation of materials,ecology, the disposal of possible accidental leaks or gases, etc.

• The safety of the plant’s personnel, including fire fighting (see Ref-erences 9 and 10)

• The marketing of the product, where public regulation is concerned,such as for food, pharmaceutical, animal feed, or building materials

• Disposal of waste streams and possible poisonous or radioactive effects

The technological background is detailed in several basic referencebooks.

6, 7, 9, 10

Early clarification with the authorities as to proper procedureis best conducted by corporate specialists or consultants, to indicate exactlywhat factual information should be provided by the corporation to securethese formal permits, possibly in the form of an “environmental impactstatement,” required in certain regions. Then, the project manager will deter-mine if such data is already available in a convincing form, or if its prepa-ration would require any

additional testing or engineering studies

. The prepa-ration of such document can require a great deal of work from theprofessional members of the core team and their consultants, especially fora new process or product, considering the lack of exactly similar references.




• If we knew at the time of the first patent application what we knowat this present stage, how would we formulate the patent’s claims?

• Certain very simple process concepts that are almost taken forgranted can become quite complicated to design and operate in theplant, and will require careful attention to many details, to beapplied successfully.

• Major equipment packages are groups of equipment items that arepivot in the plant and should be designed or procured together, inprocess-compatible materials.

• For a critical major equipment package, the actual purchase cost isprobably a secondary consideration of the project team, as long as itremains in the reasonable range.

• The configuration of other major equipment may have to be speciallydeveloped (or more exactly modified) and designed to meet thespecifications of the new process.

• A pilot plant that is owned by the corporation is expensive, requiresin-house expertise and a relatively long time to start, and therefore,would be justified only for a long-term continuing R&D program inthis particular field.

• Any dynamic mathematical process model can only be as good andaccurate as the numerical data in its data base and this weak pointhas discouraged many developers of novel processes. It is importantto recognize the importance of this tool and to consider it as a long-term investment in the process development program.

• At a later stage, this dynamic mathematical model should be usedfor a critical task, in order to evaluate the consequences of any pos-sible change in the composition of the raw materials, the concentra-tion of possible impurities, the kinetics of mass transfer, or qualityrequirements for the new products.

References

1. Bequette, B. W.,

Process Dynamics, Modeling, Analysis, and Simulation

, PrenticeHall, New York, 1997.

2. Law, A. M. and Kelton, D. M.,

Simulation, Modeling, and Analysis

, 3rd edition,McGraw-Hill, New York, 1999.

3. Edgar, T. F. and Himmelblau, D. M.,

Optimization of Chemical Processes

,McGraw-Hill, New York, 2000.

4. Turton, R. et al.,

Analysis, Synthesis, and Design of Chemical Processes

, Simon &Schuster, New York, 2000.

5. Corbitt, R. A.,

Standard Handbook of Environmental Engineering

, 2nd ed.,McGraw-Hill, New York, 1998.

6. Meyers, R.A.,

Encyclopedia of Environmental Pollution and Cleanup

, John Wiley& Sons, New York, 1998.



7. Tedder, D. W. and Pohland, F. G., Eds.,

Emerging Technologies in HazardousWaste Management

, ACS Symp. Series, American Chemical Society, Washing-ton, D.C., 1990.

8. U.S. Department of Health, Education, and Welfare,

Air Pollution EngineeringManual

, Washington, D.C., 1967.9. Steinback, J.,

Safety Assessment of Chemical Processes

, John Wiley & Sons, NewYork, 1998.

10. Kletz, T. A.,

Process Plants, A Handbook for Inherently Safe Design

, Taylor andFrancis, London, 1998.

11. Cusak, R. W., Glatz, T. J., and Holmes, T. L., The AP column, the developmentof a high-capacity extraction column,

Trans. Int. Conf. Solvent Extraction

, 1999,427. Cox, M., Hidalgo, M., and Valiente, M., Eds., Society of Chmeical Indus-try, London. (Koch Process Technologies).

12. Becker, O., Lewis, C., Hardy, R., and Seiber, F., Axial mixing in large packedextractors, Trans. Int. Conf. Solvent Extraction, 1999, 475. Cox, M., Hidalgo, M.,and Valiente, M., Eds., Society of Chmeical Industry, London. (Koch Glisch)

13. Lo, T. C., Process development, design and scaleup using a large Scheibelextraction column, Trans. Int. Conf. Solvent Extraction, 1999, 1503. Cox, M.,Hidalgo, M., and Valiente, M., Eds., Society of Chmeical Industry, London.

14. Movsowitz, R. L., Kleinberger, R., Buchaliger, E. M., Grinbaum, B., and Hall,S., Comparison of full-scale pulsed-column versus mixer-settlers for uraniumsolvent extraction, Trans. Int. Conf. Solvent Extraction, 1999, 1455. Cox, M.,Hidalgo, M., and Valiente, M., Eds., Society of Chmeical Industry, London.(Bateman-Israel)



chapter 10

First implementation plant design: compromises and optimization

The detailed engineering design of a plant generally follows well-knownprocedures that need not be detailed in this book. Most engineering depart-ments and companies are well staffed and knowledgeable in that area; how-ever, not all of them are experienced in, or even aware of, some of the specificissues involved in “first implementation of a new process.”

This chapter emphasizes only the additional features that derive from thefact that the plant being designed is the first implementation of a novel process.

10.1 “First implementation” policy

10.1.1 Expected start-up problems

Any new chemical plant, even when it is based on a well-established industrialtechnology, involves a certain degree of uncertainty and may result in somestart-up troubles. These problems may be due to failures in equipment orworkmanship, dirt inside equipment or pipes, error of an inexperienced teamoperating under pressure, etc. Such start-up problems are expected, and theyare normally corrected during the first weeks of operation of a new plant.

The first implementation of a novel process can obviously also presentthese difficulties but, in addition, one should generally expect more seriousproblems that may require physical changes. The greater degree of uncer-tainty can be attributed to the following:

• It may have been impractical to test everything in advance, for asufficient period of time.

• High expectations influenced the decision making on the project.• A few years may have passed between the final process package

decisions and the plant start-up, and certain quantitative aspects may



have changed (i.e., in the raw materials, or in the services supplied);somewhat different factors may have been introduced, either by theteam doing the detailed design or by the equipment suppliers.

10.1.2 Design policy

Thus, in the first implementation of a novel process, it would be reasonableto specify, from the beginning of the detailed engineering design of the plant,a design policy that should allow, in general, for:

• An

over-designed capacity

of most of the individual functions. Forexample, the electrical motors’ drive power, or the diameter of thesmaller pipes, or the capacity of solid feeders could be increased atvery little cost.

• A

greater degree of flexibility

in operation, exceeding what is generallyaccepted in conventional design. For example, the following typicaldecisions should not affect the budget much but could be appreciatedin the process tune-up: installation of variable-speed drives in someof the agitators and positive-displacement pumps, larger buffer tanksbetween sections, and manually set variable-level overflows.

•

Built-in

preparations for possible

changes and additions

of hardware. Forexample, more “blind flanges” installed in the piping at the correctplaces (avoiding dead-end traps) could allow for easier future additions.

•

Additional engineering

effort with very careful attention to any possiblecause of problems, according to a detailed list prepared and agreed inadvance (see below). This is important in particular whenever well-known, conventional tools (“old horses”) are used in new applications.For example, in the early days of industrial solvent extraction, a newplant could not be operated due to a severe emulsification, which hadnot been seen in the previous pilot development work. A detailedinspection showed that the impellers installed in the liquid–liquidmixers had very rough edges, which mashed the liquids at high ve-locity. These impellers were returned to the workshop, their edges wereground and polished and this problem disappeared in the plant. Thesupplier of the impellers had extensive experience with mineral plants,mixing solid–liquid slurries, and had used the same fabrication tech-nique for this new application. After this experience it became standardprocedure to include in the specifications for liquid–liquid mixers, thisfinishing procedure, with reminders on the drawings and in the in-spector’s checklist. But this lesson should also be applied systemati-cally to every specification for adaptation of conventional equipmentto “first-time” applications.

Management should accept that the implementation of such design pol-icy may increase the final investment in the plant by about 10 to 20% (rela-tive) over standard practice. This extra margin should be accounted for in



the investment budget, but of course this reserve may be an easy target forbudget cuts during construction, unless its

importance is clearly understoodand agreed to

, as a matter of management policy.

10.1.3 Identifying probable causes of problems

The project managers have been expected to display a large degree of self-confidence when appearing before the “higher authorities” to obtain theirapproval of the investment (“nothing can go wrong, everything is undercontrol”). Then, a few weeks later, they are expected to sit with their engi-neering staff, make a list of every possible cause of problems (the worst case)and define in detail the features that would be needed to prevent or minimizeany resulting damage. This situation is very difficult and the review is often“delayed.” This psychological pitfall has been seen over and over again inmany projects in different countries and it could be very detrimental.

This problematic situation can be by-passed if the role of the pessimistic“devil’s advocate” in this review is delegated in advance to an experiencedexternal consultant, who has no psychological commitment to any previousclaims and no concern that this role may damage his or her career.

Identifying potential problems and ways to prevent them should havecontributions from the entire team. Specific professionals will be assignedto be responsible to follow up on these the detailed design process and thepurchasing specifications, and to report on any deviation.

10.1.4 “Guarantees” for reasonable plant performance

These guarantees for reasonable performance of the whole plant (or of somepart) can sometimes be provided, for a price, by the engineering companyand/or by the equipment suppliers. But as an insurance policy, they aregenerally so loaded with formal conditions and reservations that their effec-tive coverage is practically worthless. For example, it is generally stated thatthe “performance test” should be carried out within a fixed period, in theexact conditions that are specified in the initial specification sheet. Suchguarantees are sometimes used by a project manager in order to build con-fidence and possibly also to reduce personal responsibility. It is preferablethat the project team ignores these guarantees on the practical working level.

10.2 Modeling and optimization

The basic development of a dynamic mathematical model for the processhas been discussed above (Chapter 9). As a starting exercise, it was basedmostly on theoretical considerations of the chemical and physical mecha-nisms and on the process data available at that time. It has been used fora “first stage process simulation” in order to decide on the volumes ofbuffer tanks and for the basic design of the plant instrumentation andcontrol system.



As the implementation project now reaches the concrete design stage,the process team should expand the study of the different control aspects,as allowed by the limited data available. There are basic reference booksthat cover all the fundamentals, but refer mostly to “known and well-behaved” processes.

1–7

For a first implementation of a novel process, the design team mustidentify all the possible changes in the plant’s daily operation, by asking allthe relevant “what if…” questions, as illustrated in the situations discussedbelow, and then by calculating, or at least evaluating, their resulting effects.All these possible changes are then built into this model and a comprehensiveseries of balance spreadsheets are run to evaluate the possible changes. Theresults of these simulation runs are then analyzed to check if the proposedengineering design would also cover such changes.

10.2.1 Composition of raw materials

Most raw materials used in the chemical industry are subject to a normalrange of fluctuation in their compositions, which is to be expected andhandled in the plant’s routine operation. For example, merchant rawmaterials of agricultural origin have seasonal changes, as they are storedfor different periods. Raw materials coming directly from a mine orquarry depend on the geology and working program. The grade of amineral concentrate can change with the daily operation of the plant. Forexample, merchant phosphate concentrates can be in the range of 28 to32% P

2

O

5

(mostly 29 to 31%). Although the buyers would pay onlyaccording to the “official” analysis of the material lot that they receive,they cannot dictate such analysis in advance, and they have to handlewhat they receive. The same issue exists for petroleum fractions from arefinery, and so on.

The material balances and the operating model should be run for manydifferent compositions of raw materials in the “reasonable” range, coveringall the combinations (“ratios”) of possible extreme conditions. The effect ofsuch different compositions on the flow rates and the compositions of thedifferent streams should be noted and analyzed. With these results in hand,the project management team must make some hard decisions, early enoughin the design work:

• If they can afford to design the whole plant on the “worst possible”case within this “reasonable” range, they will change the basis ofdesign accordingly. The result will be a larger plant, capable of pro-ducing more whenever better raw materials are available.

• If such “worst possible” cases could occur “reasonably” only forrelatively short periods, they could accept that the plant would op-erate at a lower capacity during such periods. They would slightlyincrease the design capacity of the plant to produce more for the restof the year, in order to make up the final yearly production.



A decision such as this can have very heavy consequences and must bereached at an early stage, even with a more rudimental model. In some cases,extensive storage and blending facilities for raw materials should be considered.

10.2.2 Effects of impurities

Many impurities enter the plant with the raw materials that were notaccounted for to any extent in the basic material balances. These have generallybeen given little attention in the main process development. However, someof these impurities may have a very significant effect on multiple-phase sys-tems. For example, in crystallization, chemical compounds could affect thegrowth of crystals by adsorbing onto the fresh crystalline surface. Impuritiescould cause emulsification of liquid–liquid systems, by absorbing on the inter-face of the smaller drops. Other impurities can find their way into the finalproduct or increase corrosion on the materials of construction to an unaccept-able level. Such effects should have been observed, identified, and possiblyquantified in the previous experimental work done with “real” raw materials.

Possible solutions for these problems could include the following:

• Changing the raw material source to one that does not contain theimpurity, if this choice is available and affordable

• Adding purification steps to the process, such as an active carbontreatment or an ion exchange column (on side streams)

• Deciding to “live with it,” while increasing the size of some of theequipment and of the bleed streams

10.2.3 Changes in the kinetics of mass transfer

Any contact operation involving mass transfer between different phases willbe sized on the basis of the design material balance and on an average

coefficient

of mass transfer. This coefficient, which is based either on a definite surfacebasis or on a volumetric basis for a particular packing geometry, is generallydetermined experimentally in a pilot test, specific to the particular equipmentchosen, and scaled up according to the know-how of the supplier. However,one should ask what would happen if the mass transfer coefficient actuallyobtained in the plant is smaller than the one taken for design, for some reason?

• Can this deficiency be corrected by a change in conditions (i.e., tur-bulence) or covered in some other way? For example, in certainprocesses, the driving forces for mass transfer could possibly beincreased to compensate for a lower coefficient, i.e., by a change intemperature or pH.

• Is it possible to maintain at least the concentrations, at a lower rateof production?

• Is there any built-in oversize reserve or the possibility of adding stagesand residence time in the plant, by adding contact equipment in series?



10.2.4 Changes in specifications for the final product

The specifications for the final product have been the basis of the entireprocess development and the goal of the project preparation was to assureits quality. However, market studies have continued since (see Chapter 9)and the competition may also have been active. So it would be reasonableto assume that by the time this new product is to be distributed, there maybe a demand for further improvement, for example in the maximum con-centration of a particular impurity. Therefore, some typical questions couldbe asked at this early stage of the detailed design:

• Can some options for improvement be provided now by includingprovisions in the present plant design; for example by changingsome of the purification conditions, or by adding an extra purifica-tion stage?

• Alternatively, can the physical preparation for a possible addition inthe plant be provided, in case it is needed in the future?

10.2.5 Normal fluctuations around the designed average

A basic feature of the plant operation is that conditions in one stage dependon the results from the previous “upstream” stage. There can be, on the onehand, normal routine fluctuations in these results, which can be accountedfor, and on the other hand, some differences that could derive from presentlyunknown causes.

An example of so-called normal fluctuations is the gradual clogging offiltering screens, which require periodical cleaning. The liquid contentremaining in a filter cake, from a continuous filter or from a filtering centri-fuge, directly affects the evaporation load in the downstream dryer. If themoisture content actually obtained in the plant is higher than the averagemoisture content that was taken in the process design, this dryer couldbecome a bottleneck for the whole production, unless additional featureshave been built in to allow the increase in its drying capacity.

Consider, for instance, a cake of (water-soluble) crystals from a contin-uous wet screening centrifuge, with a so-called “wedge-wire” conical basket,which is treating the slurry product from an industrial crystallizer. A typicalrange of its moisture content could be about 3 to 5%, which means that whenthe screen is clean, in the first hour of operation, the cake may contain 3%moisture or less. However, any slurry feed likely contains crystals havingthe exact size of the slot aperture of the “wedge-wire” screen, and these getstuck and progressively clog the free draining area. Thus, the moisture con-tent of the cake gradually increases and when it reaches (say) 5%, the feedstream is stopped, and the screen is washed with a close-circuit of hot waterto dissolve all these obstructions. Then the cycle is resumed.

In a large installation, where four to five such screening centrifuges areoperated in parallel to process the total tonnage required, the operating



practice is generally to arrange a rotating cleaning schedule, where forinstance, each machine is operated for 4 hours and then stopped for 1 hourfor cleaning. The mixture of cakes from the four operating centrifuges shouldgive a more or less steady average around 4% moisture and this can be takenfor designing the downstream dryer.

In smaller installations, there will be larger fluctuations, unless a bufferarrangement is installed on the cake stream to the dryer (i.e., wet solidsblender and storage).

Centrifuge suppliers are very experienced and if they are given the fullpicture of the upstream and downstream conditions in the tender specifica-tion, most of them will recommend an efficient rotating cleaning scheduleand give very good advise in the detailed design. However, unfortunately,many cases have been seen in which these suppliers were asked in the tenderto compete only on the moisture content and on the cost of one machine. Itwas not surprising that many offers only state that the tests show that 3%can be obtained (with probably a reservation in small letters saying “with aclean screen”). This typical and straightforward case illustrates again theneed for complete presentation and expert advice.

Similar situations are encountered with other process equipment thatrequires periodic treatments (regeneration), such as fixed-bed ion-exchang-ers or active-carbon columns. Other types of routine fluctuations are oftencreated by the control loops that are programmed to start at a certain level(reading) and to stop at another level.

10.2.6 Differences in the performance of equipment

In the process design, if there are no such “normal” fluctuations, the resultspassed over from the upstream stage have to be assumed, either from “pre-vious experience” or from the conclusions of the experimental tests done sofar. At this point, the quantitative model should be operated to determine“what would happen if” in real life, there was a deviation from these assump-tions. How would the plant react and how could these reactions be correctedwith minimum damage? This systematic check could involve a lot of workand some timedelay, and thus, unfortunately, is not always done in projects.The three typical cases below may be instructive, as illustrations of this task:

For example, whenever a continuous thickener or decanting centrifugeis used ahead of a pressure filter, the

solids concentration

in the underflowslurry obtained directly affects, with a high leverage, the

filtrate load

and thesize of the downstream filter. It has often been seen that such solid concen-tration in a flocculated underflow slurry could decrease with the presenceof small quantities of certain soluble impurities, with so-called “dispersing”properties (they adsorb on the surface of the particles and create repulsionforces between them). If this effect is a known possibility in the novel process,but it could not be controlled and corrected in a reliable and positive way,the filter should be over-sized (at this stage!) or an additional thickener mayhave to be added (possibly later!).



Another field illustrating this problem relates to the

multistage countercur-rent decantation scheme

, CCD, for washing of solids from soluble components.These CCD processes were developed long ago for the hydrometallurgy ofcopper and other base metals. In such applications, the ore is finely groundthen treated with acid to leach out the metals and other soluble components.Then the solids must be separated from the solution, while aiming at a max-imum recovery of the valuable solubles from the waste solids, and the solutionis then further treated to recover the valuables. This separation cannot bepractically achieved on a filter, due to the fine nature of the solids and to thelarge tonnage involved. It is usually done by a series of countercurrent stages,each involving a dilution and decantation in a thickener, as illustrated in Figure10.1. The underflow stream is pumped, while the overflow stream could eitherbe pumped or transferred by gravity if the plant’s layout allows.

In the last decades, similar CCD processes were also developed and usedextensively in an opposite way, for the extensive cleaning and purification ofvarious “high-tech” minerals, which are intended to be used as fillers or for fineceramics, or of “special” powders which are generated by chemical precipitationof very fine particles. In such cases, the process efficiency is measured by thevery small amount of residual soluble impurities remaining with the solids.

The efficiency of this separation, or the recovery of the solutes, is directlydependent on the ratio of the liquids contained in the underflow and over-flow streams and can be calculated exactly by a rather straightforward math-ematical model with a 0.0000 format. (This would be a good exercise forthose chemical engineers who believe that all numbers in a chemical engi-

Figure 10.1

Countercurrent decantation process for washing of solids.

washed solids

washing waterslurry to

CCD

solution from CCD

wash 2 wash 1wash (n-1)wash n



neering calculation should have no more than three significant figures! Thiswas not true even in those days when most calculations were done on aslide-rule and CCD calculations were done slowly by solving a set of six toseven equations with six to seven unknowns with “determinants”!).

The amount of wash water (overflow) used per ton of solids is limited,and generally fixed by practical considerations, such as the dilution of thevaluable in the resulting solution, and the size of the thickeners. Therefore,the separation efficiency depends critically on the

solids concentration in theunderflow

slurry stream. Table 10.1 illustrates the relative part (in percentage)of the entering solutes that remain with the solids after four, five, or sixcountercurrent stages, using 3 tons of wash water per ton of solids, withdifferent solids concentrations in underflow slurries. One can also see thevery striking effects of these two factors in the plot in Figure 10.2.

Table 10.1

Percent of the Inlet Solubles Remaining with the Solids

Percent Solids in the Underflow Slurry 6 Stages 5 Stages 4 Stages

40 0.7874 1.5873 4.761942 0.5157 1.1261 3.572544 0.3365 0.7959 2.671946 0.2188 0.5604 1.992748 0.1418 0.3932 1.482150 0.0915 0.2747 1.0989

Figure 10.2

Residual solute withthe slurry, as a function of the per-cent solids in U slurry for four, five,or six stages

0

1

2

3

4

5

35 40 45 50 55Perc. solids in U

Per

c. s

olut

es r

emai

ning

6 stages 5 stages 4 stages



In real life, the solids concentration in the underflow slurry stream couldchange daily in the plant according to the pH, or with the nature and dosingof a flocculating agent, or due to some excessive attrition of the slurryupstream. One can see, therefore, that even a rather simple “old” processstill requires a large degree of advance care regarding the design conditionsand the effective process control, starting from the identification of the criticalparameter and the factors that could cause it to change, and of the meansto correct such changes.

In the third example, each of the exit aqueous streams from a solventextraction plant is steam-stripped to eliminate and recover the remainingsolvent “dissolved” in it. The design of the steam-stripper is therefore basedon the solubility and vapor pressure data determined in the lab tests. How-ever, there

could also be some entrainment

of microdroplets of the solvent phaseinto these aqueous streams in the plant. This effect could be due to theimperfect operation of the equipment’s settling zones, or caused by occa-sional impurities unaccounted for. Since such entrainment is not a “normal”constituent of the process, the plant’s designers would generally not concernthemselves with this complication, unless the possibility has been specificallyintroduced and quantified in the process package. Then, the designers ofsuch operations should ask themselves:

• What would happen with the microdroplets of solvent in the stripperand how can one assure the standards requested for the exit streams?

• Should the option be introduced in the design “just in case” forincreasing (how much?) the steam rate, or the temperature, or thevacuum, with the resulting increase in equipment size?

• Would it be preferable in a large installation to have a decantingsupercentrifuge stand by ahead of each stripper, to catch eventualdroplets?

10.3 Critical pilot testing

In Chapter 9, the pilot testing of specific process operations was discussed.This piloting was required to

confirm expected results

and the

detailed quanti-tative specifications

for particular equipment items, operating with the exactstreams of the new process, before the whole process is proposed for imple-mentation. In addition, larger quantities of intermediate streams (or finalproducts) were required for further testing of the downstream operations.

These requirements probably necessitated the continuous operation of oneor several pilots, equipped for collecting both the necessary data and theresulting streams, for relatively long test periods (for example, a few weekseach). The typical examples discussed there included a multiple-effects evap-orator and a liquid–liquid contacting battery for solvent extraction.

The reliable detailed design of a multiple-effects evaporator industrialinstallation required, for instance, experimental determination of the heattransfer coefficient for different concentrations of the solution and different



velocities in the tubes; the long-term performance of the heat exchangers;the behavior of the boiling solution inside, such as frothing, splashing, pre-cipitation, and possible encrustation of solids; etc.

For designing a “horizontal” battery of mixers-settlers, in which eachstage is assumed to be practically at equilibrium, all the process aspects canbe calculated reliably from the results of bench-scale equilibrium tests. How-ever, if a vertical column liquid–liquid contactor is preferred, it cannot bereliably sized without performing some pilot testing for each case with theactual materials, in order to determine: the acceptable velocities, the heightof a theoretical contact stage, the behavior of the phase mixture (observa-tions), the starting procedure until a steady-state operation is reached, andso on. Before the whole process was proposed for implementation, such apilot would have been organized with a chosen supplier, with their ownportable pilot installation and expert staff, for process demonstration andagreement on the equipment sizing. Now, after the approval of the imple-mentation and concurrently with the detailed design, some additional criticalpiloting may be necessary on very specific issues.

10.4 The process package

The need for a process package, for the implementation of a newly developedprocess, may seem obvious but, in fact, has not been universally accepted.It is still not used in many projects, and its absence does create many mis-understandings and problems.

The

process package is the essential basis

for the design of the plant. Whenworking on a large project on many different fronts, important process itemsshould not be decided under the day-to-day pressure of detailed engineer-ing. All the decisions that could affect the new process operation and resultsshould, as far as possible, be included in the process package, after they havebeen well thought out by all the scientists and managers who participatedin the novel process development and in the project definition, and whoshould therefore be well aware of the possible implications of such decisions.Of course, there will still always be a need for further consultations, but onrelatively few specific points.

The

content of a typical package

, described in detail in Appendix 1, ispresented mostly to give an indication of the general scope, and it shouldbe considered as a

checklist

to be adapted to each specific project. Its mainsections are:

• Definition of the “black box” objectives, raw materials, and products• Division into functional sections, as illustrated in a block diagram,

with definitions of their function, interconnecting streams, recycles,closed loops, and buffering

• Separate discussions for each of the sections, with the process flow-sheet, the operating variables and the design data used (sources)

• Material and heat balances, with any modeling already available



• Major items of equipment — functions, choice, considerations, andpreferences

• Services required — options, sources, and costs• Materials of construction — options, “least expensive but reliable”• Safety aspects• Disposal of waste streams

The

first version of the process package

should be prepared and reviewedby the process development group, then approved by the project managerand transmitted to the engineering company, the operating group, and any-body else involved in the project (managers, consultants). Some engineersfrom the process department of the engineering company may have alreadyparticipated in the early preparation of the process package, as consultantsor service providers.

This key procedure (approval and transmission) is often called the“freezing” of the process for design. Still, this process package will be furtherrevised two or three times during the detailed engineering work, followingpossible significant decisions, or necessary changes in the equipment or inthe control scheme. The process package will be finally completed with theplant’s operating results in the consolidation stage (see Chapter 12).

The bulk of the process package is a compilation of written materialfrom many different sources, which can probably be found in the workingfiles of the different people who participated in the project from the begin-ning. The checklist of a typical package, given in Appendix 1, could serveas a working tool for organizing the compilation of the package. Thus, mostof the man-hours in the preparation of the process package are devoted tothe orderly organization of all these documents according to a preset sched-ule, leaving clearly indicated space for whatever is still missing. Some editingwill probably be needed to make the compiled document as uniform,friendly, and accessible to new users as possible. This can also be an instruc-tive task for new members of the team.

Most of this material should be prepared and reviewed in draft formwell in advance, as early as possible before the detailed engineering is begun.Engineering companies usually present to the client’s project manager, inthe first few weeks of the contract, all the usual engineering “design criteria”that they propose to use for the different disciplines: civil, mechanical, elec-trical, instrumentation, material handling, etc. The review and approval ofall these books takes a lot of time and could well distract the attention ofthe project management from important decisions on process issues.Advance preparation therefore minimizes the delay in completion of theprocess package and its approval for distribution.

As described further in Appendix 1, the

“black box” representation

definesthe streams entering the plant (raw materials, streams and services from adja-cent plants, chemicals and additives) and streams exiting the plant (products,waste streams, gaseous emissions). In other words, this is a definition of whatis done inside the “black box,” without describing how it is done.



This “black box” is a very useful tool that allows accurate descriptionof the nature and extent of the project to those who need not be botheredwith “the technical details,” or outside people who are not allowed into theconfidential aspects of the novel process. With the widening of the externalfront, this tool will be very much in demand from this stage on.

A typical example is illustrated in Figure 10.3, for the process for DAP thatwas described in Chapter 5, and presented as a block diagram in Figure 5.1.Note that, despite its simplicity, this “black box” representation can also bedevised to emphasize the two main “sales points” of the proposed process,which should be appreciated by people operating in this field, namely that:

• Half of the P

2 O 5 used comes from phosphate rock concentrate andhydrochloric acid, and should be much cheaper than in the concen-trated WPA, which constitutes the second half.

• At least some of the impurities in the WPA raw material are alsoeliminated, resulting in an upgraded DAP product.

10.5 The role of the engineering company in the first implementation of a novel process

10.5.1 The interests and limitations of the engineering company

The engineering company may, in certain cases, be a corporate engineeringbranch but in most cases is an external independent company, with satisfac-

Figure 10.3

Black-box illustration of a process for DAP (all figures in MTY).

Ammonia 26,000

WPA 50% P2O5

P2O5 27,000

18% HCl soln. 390,000

HCl 70,000

Phosphate 31%P2O5- 87,000

P2O5 27,000

impurities

insolubles

CaCl2soln.

DAP 100,000

50,000 50,000

ProductWaste



tory relevant experience and work record. The engineering company has anessential role in the implementation, and it is important that everybody onthe implementing team understands exactly the objective interests and lim-itations of any engineering company.

In most cases, a few representatives of the engineering company selectedmay have already participated in certain aspects of the development effort,in direct collaboration with the promoters and the corporate team, as pilotdesigners, consultants for equipment, or in preparing economic calculations.As these individuals contributed to reaching the implementation decision,it is quite normal that the developers and corporate teams would considerthem, on the human level, as good “friends and partners,” with close work-ing and personal relations.

However, once a comprehensive contract has been signed for the supplyof design and some other services (including possibly their assistance inprocurement activities and construction supervision), a lot of money is nowinvolved. Thus, any engineering company will normally behave as a separateorganizational entity, with its own characteristics and legitimate interests.

The extent of the services contracted from the engineering companycould derive also from the availability of an experienced

construction manager

(for chemical plants), whose contribution can be critical to the whole project.Such individuals are very scarce, and to recruit a good construction managerfor the project, who would be available for the right period, it may be wellworth making exceptional organization combinations.

10.5.2 The engineering company and the project manager

The engineering company operates in direct contact with the project man-ager, who is the client’s representative authorized to make decisions withinthe contract. The private and public aspects of this relation and the attribu-tion of responsibility are generally quite complex and require great care fromboth sides. There are certain characteristics in their relations that must bepublicly recognized and appreciated, to avoid pitfalls.

The first is obviously payment for the engineering services. Althoughall the financial terms of the engineering contract are supposed to be settledin advance, as with any external contractor, the contract can hardly foreseeeverything. There are generally more “extras” in a first implementation of anew process. There is a give-and-take situation in which the two sides arenot free: the project manager has to deliver a working plant in time and theengineering company has to maintain its good name, and possibly other jobswith the corporation. But if “money” becomes a central issue in the relation-ship, it could affect negatively the effectiveness of the engineering function.

The engineering company is expected to assist publicly the project man-ager and often acts as his or her representative in relation to other contractorsand suppliers, mostly on technical matters, but occasionally also on financialaspects. But this is a small world, and one should recognize that the engi-neering company may have its own interests, from other long and complex



interactions with these contractors on other projects. On the other hand, ifthe engineering company action for the project manager results in a betterdeal, this may justify their requests for “special” financial remuneration.

10.5.3 Specialization

The work of a typical engineering company is characterized by

specialization

in almost all its departments, which consists mostly in the adaptation ofpreviously successful designs. This basic feature is encouraged in mechani-cal, civil, piping, or electrical engineering, since it should lead to “safe andsound” designs. In these disciplines, innovations are generally limited,unless the client specially requests some new feature in the design, such asan unusual “span” between columns, or pipe support, etc. The rule is “takeno chances” to avoid failure and penalization.

Whenever new materials, equipment, or design methods are essentialto the success of the project, this requirement should be specified clearly inthe contract. Even then, a formal “guarantee” will generally be obtained bythe engineering company from the supplier and transmitted to the owner.All such formal blankets should be well recorded and double-checked withindependent experts. In many cases, it is specified from the beginning in thecontract that a well-known independent expert will give the necessaryinstructions on a particular issue to the engineering company (which isgenerally happy with such arrangement).

10.5.4 The chemical process engineering department

The chemical process department of the engineering company is generallycharacterized by very heavy fluctuations in workload. In a new project, alarge number of specialized man-hours is invested in the first 3 to 6 months,to receive and assimilate the essentials of the new process, organize the P&IDflow-sheets, the balances, the lists, the process specifications of the mainequipment, the preferred suppliers, etc. All this work is needed in a hurryand under pressure, to allow the engineering company to “deploy all itsforces.” After that period, the participation of the process engineering depart-ment is reduced very much, mostly to “checking and polishing.”

One should also note that on the formal side, the engineering companyalways disclaims responsibility for any process aspect that has not beenspecifically and emphatically stressed by the process developers, andincluded in particular in the process package. However, how could theyundertake to design and build a plant without really understanding theprocess? Therefore, their chemical process engineering department isassigned to assimilate the essentials of the process, without spending toomuch time and without going in depth.

As a result of these limitations, the type of chemical engineers who aregenuinely interested and professionally trained in new process developmentare generally not induced to work for a long time in this function in an



engineering company, where their competence is not used all year round(unless they are in one of the few leading positions). Many of the youngerprocess engineers spend a few years there in order to “learn the ropes,” onthe way to a corporate management function.

In other cases, they may feel that their creative contribution to the finalresult was not really appreciated by the process developers, and this feelingcould lead to tension between them on the personal level. If such counterpro-ductive tension develops, it should be recognized at an early stage by the projectmanager and corrected by demonstrative recognition steps, to maintain theirprofessional stature. The active participation of these process engineers in the“critical piloting,” discussed in Section 10.3 above, could help in this matter.

10.5.5 Timetable

Another important aspect is that the engineering company is always workingwithin a rigid and critical timetable, imposed by their formal obligations.Thus, from their point of view, decisions must be made at fixed dates,whether all the information required is available or not. Some of thesedecisions may involve only expenses (i.e., over-design on the safe side), whileothers may affect the results of the process’s operation.

The intergroup relationship should be focused on getting all the relevantaspects well understood and documented at the time of the decision. Buthere, a conflict could derive from the project manager’s requests to workout more alternatives, more optimization and more checking procedures,according to his management judgment. Since most engineering companiesare working generally for a fixed fee, such extra work is not welcome, unlessthe project manager has specifically requested it during the contract negoti-ations. These pressures could lead to shortcuts, which could be the cause ofmany problems that will appear later during the plant’s start-up.

10.6 Detailed engineering documents

Detailed engineering work always produces a very large number of docu-ments, specifications, drawings, tables, purchase requests, summaries ofmeetings, budget accounting, etc. All these documents are dated, numbered,recorded, divided into disciplines, and reviewed daily by the different mem-bers of the project manager’s team, each in his field. This working procedureis commonly used in any detailed plant design and need not be expandedon here. However, the following remarks should be noted for a new process.

The main concern is that between these thousands of decisions, somefeatures may be introduced that may adversely affect the operation of the newprocess. But it is practically impossible for the inventors or the process devel-opers to review all, or even most, of these detailed engineering documents.They would not have the time, or the competence in the technical details andjargon. Their process review can only be effective on those decisions concern-ing the main equipment specifications and mostly on the

Operational Manual

.



This document describes, in detail and step by step, how the plant isintended to be operated and controlled, from its empty start to its steady-state operation, through every conceivable cause of problems (each with itsdiagnostics and its remedy), including the occasional stoppage. This manualwill include periodic jobs and routine maintenance functions.

The main management issue is the time scheduled for preparationand review of the operational manual. It is generally much more conve-nient for the engineering company to delay the preparation of this manualuntil the finishing stage, after the vast majority of their work has beendone. Then, their key engineers will be less loaded and the manual canrefer exactly to the concrete details, as finalized in the last revision of theP&IDs. But if this manual will be reviewed with the process developersand the operating staff only at this late occasion, most of the changesthat may be then requested would need serious rework and revisions,and some of these changes could be too late altogether, after the purchaseof the major equipment. This situation has been often seen, leaving nochoice, forcing more compromises and resulting in personal tensions andaccusations.

Therefore, it is advisable to provide from the start, in the engineeringcontract for the first implementation of a new process, that a first draftof the operational manual be prepared and transmitted with the firstrevision of P&IDs. This first review will give to the process developersthe opportunity to stress all the important aspects, in their opinion, atthat early occasion.

A revision of the operational manual should then accompany every laterrevision of the P&IDs and should allow for continuing review. It will be theresponsibility of the engineering manager and his team to see that the itemsthat have been stressed by the process developers will be maintainedthroughout the detailed engineering documents.

10.7 Final review and approval for construction

With the conclusion of the detailed engineering, the project manager willdistribute a complete set of the final revisions of the plant’s design docu-ments to all concerned with the final review. These include:

• The P&ID drawings• The operational manual• The purchase specifications for all the major process equipment, with

the definite offers negotiated• The revised investment budget

The final comprehensive review often takes a few days of quite inten-sive meetings. As a result, the formal approval for construction isreleased, possibly with some modifications calling for the reworking ofsome items.




• In the first implementation of a novel process, a specified designpolicy should allow for over-designed capacity of most of the indi-vidual functions, a greater degree of flexibility in operation, built-inpreparations for possible changes to or addition of hardware, andcareful attention to planning for possible problems.

• The task of defining possible problems and planning to minimizedamage could be delegated in advance to an experienced externalconsultant.

• Specifications for the final product have been the basis of the processdevelopment, but by the time this new product is to be distributed,there may have been demands for further improvement, for examplein the maximum level of some impurity.

• The “process package” is the essential basis for the design of theplant. In a large project, important process items should not bedecided under day-to-day pressure. All the decisions that affectthe new process operation and results should be included in theprocess package, after they have been well thought out by all thescientists and managers who participated in the novel processdevelopment and are well aware of the possible implications ofsuch decisions.

• The work of a typical engineering company is characterized by spe-cialization in almost all its departments and innovations are generallylimited. Whenever new materials, equipment, or design methods areessential to the success of the project, this requirement should bespecified clearly in the contract.

• The chemical process department of the engineering company isgenerally characterized by very heavy fluctuations in workload. Ona new project, a large number of their specialized man-hours is in-vested in the first 3 to 6 months, to allow the engineering companyto “deploy all its forces.” After that, their participation is reducedvery much, mostly to “checking and polishing.”

• The engineering company is always working within a rigid andcritical timetable, imposed by formal obligations. Decisions mustbe made at fixed dates, whether all the information required isavailable or not. Some of these decisions may affect the results ofthe process’s operation.

• In the first implementation of a new process, a first draft of theoperational manual should be prepared and transmitted with thefirst revision of the P&ID, to give the process developers the op-portunity to stress all the important aspects that should be includ-ed. A revision of the operational manual should then accompanyevery later revision of the P&ID and continuing review should beallowed for.



References

1. Seaborg, G. E. et al.,

Process Dynamic and Control

, John Wiley & Sons, NewYork, 1989.

2. Stephanoloulos, G.,

Chemical Process Control: Introduction to Theory and Practice

,Prentice-Hall, Englewood Cliffs, NJ, 1990.

3. Coughhanover, D. R.,

Process Dynamic Modeling and Control

, 2nd ed., McGraw-Hill, New York, 1991.

4. Ogunnaike, B. A. and Ray, W. H.,

Process Dynamics, Modeling and Control

,Oxford University Press, New York, 1994.

5. Luyben, W. et al.,

Plantwide Process Control

, McGraw-Hill, New York, 1999.6. Svrcek, W. Y, Young, B. R., and Mahoney, C. P.,

A Real-Time Approach to ProcessControl

, John Wiley & Sons, New York, 2000.7. Cluett, W. and Wang, L.,

From Plant Data to Process Control Design

, Taylor &Francis, London, 2000.



chapter 11

Running in and adjustments in the new plant

11.1 The plant construction period

The plant construction period may be between 10 and 20 months, depend-ing on the size and complexity of the plant, the site location, and conditions.There is no need to detail here the various activities concerned with con-struction of the new plant from the detailed engineering documents thatwere approved. These activities are adapted to the particular case andinclude the purchasing, procurement, and inspection of hardware andservices, supervision of field contractors, and quality control of materialsand equipment.

The practice of the construction site management is dominated by theauthority and experience of the construction manager and supervising team.As mentioned before, a good construction manager is always in greatdemand and should be “booked” well in advance for the project. In the caseof a first plant for a novel process, the practice is not basically different butextra care should be taken to avoid “unseen” deviations and shortcuts fromthe documents that were approved for construction, which could ultimatelyaffect the process operation.

While the construction manager will be busy handling suppliers andcontractors, the project manager and his team will still be fully occupiedwith the following tasks:

• Selecting the new plant management team, within the relevant cor-porate organization. This is of course a critical choice. Once this teamis selected and available, the project manager will introduce theminto the project, while establishing a gradual program for thoroughteaching of all the features of the new process and its implementation,and for handing over the plant management to them.

• Assembling and training the operating personnel, together with thenew plant management team (see Section 11.2 below).



• Completing R&D activities, and summing up and consolidating R&Dreports, while maintaining links with the promoters/inventors, rel-evant corporate R&D managers, and any external organization con-cerned (i.e., funding committees).

• Summing up the contractual procedure with the engineering com-pany so far, except for their participation in the work of the construc-tion manager’s team or in the start-up effort.

• Handling the formal interactions with statutory authorities to securethe necessary permits and establish procedures.

• Coordinating the work of the marketing team, which is preparingdistribution channels and should be ready to sell the new productsas soon as they are available.

11.2 Assembling and training the operating team

11.2.1 Recruitment

In the 6 months preceding the expected start-up date, the members ofthe operating team will be recruited, designated, or transferred, accordingto the company’s organization framework, starting with the key person-nel (plant management team) and with the plant’s maintenance team.This assembling is very important, quality-wise, but different proceduresmay be used, depending on local conditions, in particular whether thenew plant is on a new site or if it is part of a larger existing plant. Mostcompanies insist on individual health and psychometric testing and onconfidentiality contracts, and these procedures take time. For a first plantwith a novel process, the previous experience and psychological profileof this personnel may be very important, in particular their patience andperseverance.

11.2.2 Maintenance

If possible, the newly assembled plant maintenance team is temporarilyattached to the construction manager and put to work on the close supervi-sion of the site contractors during the advanced stages of the installation ofthe equipment and the assembly of the piping. This proximity will give tothe maintenance team more extensive knowledge of the hardware than canbe obtained from the drawings or from verbal explanations only (“seeing isunderstanding”).

11.2.3 Training

An extensive training program will be conducted to familiarize the operatingteam with the site, the different sections of the new plant, the details of theprocess, the raw materials and products, and the operating procedures. Themembers of the process engineering team, who designed the plant, and the



different consulting specialists (controls, safety, quality assurance) will domost of the training, in the form of lectures and written material, and com-prehensive feedback tests.

The inventors/developers should also be invited, if possible, to partici-pate in this training program, in order to emphasize the more importantaspects of the process, from their point of view, and be reassured that theseaspects have been well assimilated. Their participation is also important fortheir personal acquaintance and appreciation of the plant’s team. This per-sonal contact will “defuse” in advance possible accusations of inadequateselection or training, which may burst out later under the pressure andexcitement of the usual start-up problems.

11.2.4 Safety

The general training will include also all the

safety

aspects relevant to thenew plant, in their basic substance as detailed in the operational manual (seebelow) and in the forms that may be required by the local law or by theinsurance company. Generally, such training is given or supervised by aspecialist, including the detailed inspection of the relevant hardware. Forexample, in certain locations and depending on the classification of plant,an individual examination/accreditation on safety issues may be requiredat the end of the training.

11.2.5 Functional organization

After the general training described above, the plant personnel will bedivided into the relevant functional groups and each group will be givenmore detailed training on the equipment and procedures within their fieldof responsibility, under the direct supervision of the plant management (their“new bosses”). These functional groups would consist, for example, of theoperators, the instrumentation and control technicians, the QA (qualityassurance) and laboratory staff, the material handling and warehouse per-sonnel, the office and communication team, etc.

The inventors/developers will normally participate more in the trainingof the groups concerned with process control, laboratory analyses, datareporting, and quality assurance methodology. In particular, they will inter-act more with the process (or shift) engineers who will have to take theroutine decisions, and should be preparing for the process optimization (seebelow in Section 11.6).

11.3 Preparation for start-up

11.3.1 “Dry runs”

In the last stages of the plant assembly, “dry-run” tests are conducted underthe supervision of the construction manager’s staff, with mixed teams of the



contractors and the new plant operating staff

. In the professional jargon, dryruns indicate those tests that are done

before

the actual raw materials orauxiliary chemicals are introduced in the plant.

During the construction and installation of the equipment, close super-vision and measuring were done to ensure that the work was executedproperly, as designed. These dry run tests are now intended to confirm thefunctional aspects. The field contractors expect to get their formal “certif-icate of completion” according to their contract, after execution of thefinishing touches. The plant’s operating team will get their first hands-onfeeling of the live plant.

The dry runs start generally with the internal cleaning of all the equip-ment and pipes, closing of all seals, checking all electrical connections, fillingwith water, conducting hydrostatic tests and pressure tests with waterand/or air, to detect leaks. After that, water is pumped around, while com-missioning proceeds of the steam and compressed air systems, heating andcooling, checking fans and blowers, burners, etc. Then, the more delicatefield instruments are installed and calibrated, and all the connections to thecentral control room are checked for response and accuracy. The controlcomputers are connected and their output is checked.

11.3.2 The plant manager

With the completion of the dry runs and any necessary corrections,

themain responsibility for the physical plant will be formally transferred

from theconstruction manager to the plant manager (or supervisor). With this for-mal change, the contractors’ staff leaves the fenced area with all theirbelongings, and if they are needed in the future, they will be considered“visitors” within the framework of the safety procedures. The plant’s main-tenance staff will then closely supervise any finishing job required from acontractor during such visits.

11.3.3 The construction manager

After formal handing over of the management of the plant, the constructionmanager and construction team will remain on the site for a few more weeks,mostly in their offices, to finish the paper work, formalities and accountswith all the contractors, but they will still be available if needed for consul-tation and any ad hoc assistance.

11.3.4 The project manager

The project manager and his or her team will operate, from now on, onlyat the corporate level and the timing of their phasing out will depend ontheir other projects and their relative priorities. The project manager shouldstill be in charge of the consolidation of the new know-how, as detailed inChapter 12.



11.4 Preparation with real materials

After internal draining and drying all the equipment and pipes, anyrequired internal flowing inventory is prepared and installed. For example,in a solvent extraction plant, mixing of three to five components may benecessary to make a solvent stock. In other plants, mercury is filled intoelectrolytic cells, or resins into columns or fluid-bed reactors, or scrubbingsolutions into a flue-gas treatment unit. In addition, boiler-feed water isfilled into the steam boilers circuit, soft water into the cooling water circuit,and so on, as needed.

In many cases, this filling has to be accompanied by some pre-pretreat-ment (transfer, formulation-mixing, neutralization, filtration, ion-exchange,etc.) and this hands-on operation gives to the staff their last occasion topractice such procedures and all the relevant analytical controls, without thepressure of the running production.

The tanks and silos for the raw materials and other additives are filledwith real materials and these operations allow also practicing the materialhandling procedures, including the records, weighing, sampling and analyt-ical control.

11.5 Strategic options for the running-in of the new plant

At this point, it would be nice if the operating staff could start running theplant according to the written operating instructions and at the designedcapacity, and begin making products for sale and profits for the corporation.This may well be possible in certain cases, but it cannot be taken for granted.Therefore, it would be prudent to expect that, in most cases, some problemswill be encountered and to make the necessary mental and organizationalpreparations to handle those situations.

11.5.1 Possible causes of problems

• Errors in the detailed design or execution of certain features. Theseerrors may occur in any plant, despite extensive checking and super-vision. The effects should be apparent in a short time, but identifyingthe causes and making corrections may be complicated. Therefore,quite often, it is decided to delay correction until the whole pictureis clarified, or “until convenient,” and this situation may cause tem-porary constraints and limitations in the normal operation.

• Occasional human errors of the new operation staff. Experiencedmanagers reduce these errors with additional close supervision, inthe early period.

• In the new process design, certain operations have been purpose-fully over-designed, or provided with a larger range of options foradditional flexibility, due to incomplete information available at thetime. For instance, variable-speed drives on the mixers, or flow



control on recycle loops affecting hydraulic loading or reflux. Thefinal optimization was referred to the running-in stage and now asystematic series of runs must be done in controlled conditions,before the optimum is chosen. This procedure may delay passageinto regular production.

• The detailed composition of the raw materials may have changed,or at least different options may now be available, since the basicR&D was done. The process conditions must be re-adapted to thenew raw materials, and this may require a series of closely con-trolled runs.

11.5.2 Unsatisfactory results

These problems may cause, during the start-up period, one or more of thefollowing, hopefully temporary, unsatisfactory results:

• A

product of lower quality

that cannot be marketed to the intendedclients, who are expecting to receive the promised quality. The qualitydeviations could be in the chemical analysis (concentration or impu-rity) or in the physical characteristics, such as the particle size distri-bution or color. Such “off-spec” product may have to be recycled, orsold if possible as a cheaper lower quality or, in certain cases, it mayhave to be dumped as waste.

• A

lower than expected recovery

, as a large part of the valuable compo-nents end up in waste streams. This may be due to incomplete reac-tions or transformation, or to unsatisfactory phase separations (en-trainment of one phase into another stream). If the final products areof acceptable quality, production may continue, possibly at a loss,while the problem is being identified and solved.

•

No production at all

, due to internal problems preventing normal plantoperation. Examples of such problems could be severe leaks, theemulsification of one liquid into another, the encrustation of solidprecipitates on heat exchanger surfaces or valves, the clogging ofpipes, filters or centrifuges, or settling of coarse particles from a slurryat the bottom of a mixed tank. Obviously, this dramatic situation willcall for a mobilization of everyone who could contribute to findinga solution, and executing the necessary changes.

11.5.3 Start-up strategies

One of the following start-up strategies could be tried, in order to reducethe damage caused by such problems:

•

Starting at a low production rate

(for example 25 to 30% of the nominal)in order to make salable products, if possible. The lower productionrate would increase the residence time in every operation, improve



the reaction yields and the phase separation results, and allow forthe increase of recycle rates (in those processes in which such recyclesare built in). The lower rate also allows better operator and instru-ment response to any unforeseen change. Then, once the plant is on-stream and making “on-spec” products, the production rate couldbe gradually increased, for example by 10% every week under fullanalytical process control, while recording the systematic trends inqualities, reactions, and separations. If or when these trends appearto exceed the allowable range, a step is taken backwards into the“safe range,” and the identification and correction of the problemmade while the plant is working and producing. This strategy isgenerally preferable and the financial penalty is limited, as probablythe marketing front may not be ready to sell all the nominal produc-tion from the beginning. But it is not always possible, as certainprocesses cannot be operated in this way.

•

Allowing a lower-than-expected recovery

while starting near the nominalinput of raw materials, if salable “on-spec” products can be assuredat a lower production rate. That scenario assumes a lower degree ofcompletion of the reactions or a lower separation efficiency. Thisstrategy is generally acceptable in the running in of large mineral-based plants that are using cheaper “off-the-mine” raw materials.This may not be possible for all processes, and in any case wouldincrease the content of “valuable” or intermediate compounds in thewaste streams.

• In some cases, the new process can be operated with a

better qualityof raw materials

, although this particular plant was justified on thebasis of cheaper, more impure raw material. (This situation is typicalfor instance for processes starting with various grades of phosphaterock or concentrate.) One could start up the plant with the better,cleaner, and more expensive raw material, to avoid surprises causedby impurities in the raw material and establish that the whole plantis working satisfactorily. Then, the cheaper impure raw materialcould be gradually mixed in increasing proportions (20%, 40%), withfull analytical process control, while recording the systematic trendsin the qualities, reactions, and separations that may be caused byspecific impurities. Whenever the allowable range appears to be ex-ceeded, the identification of the problem can be focused. A step canbe taken backwards into the “safe range,” and a solution devised bychanging some operating conditions or adding a separation step,while the plant is working and producing.

• On-off operation. If the plant can be separated into independentsections, one could work each section separately, using and fillingthe intermediate buffer tanks and silos, and then stop for analyticalcontrol and consultations. If an adequate product is obtained, it istransferred into the shipping storage. If the product is not satisfactory,it is recycled and the process started again. This strategy is often



opted for new plants based on batch operations, such as fermentationor organic syntheses.

• In the worst case, if the plant gives an unsatisfactory product fromthe beginning, the following questions should be asked until this iscorrected:• Could the “non-spec” product be recycled in the plant?• Could the lower quality product be unloaded into some other

markets?• Would the intended clients wait?• How could the cash flow deficit be handled?

11.6 Stabilization of production

After start up, the main short-term aim of the plant management is to

stabilize

the production at some level that is consistent with both the plant’s presentcapabilities, on one hand, and the present marketing possibilities of theproducts, on the other hand.

As regards the production capability, in addition to the lack of experienceof the operating team, some physical bottleneck may have been identifiedand a program devised to correct it. Until this correction is effective, thepractical production capability of the plant is lower than the nominal.

This limitation may not be really hurting yet, since it most likely hadbeen anticipated in the project presentation that the full marketing volumeanticipated would not be realized in the first year of operation. There is nopoint in producing only to fill the warehouses.

11.7 Demonstration run and project success report

In order to call the whole project “a success,” the project manager must beable to report that the plant is capable of performing all its anticipatedfunctions, in nominal quantities and quality. In addition to the personalcareer and status of the project manager, there may be some contractualclauses involving other parties that are dependent on this statement.

An often-used solution for this situation is to organize carefully a 24-hour demonstration run in which the whole plant is operated in “favorable”conditions, and everybody would be fully mobilized to assist in order toobtain a good report.

Of course, all concerned are well aware that the plant does not operate inthat way all year-round, but it is rightly claimed that the accumulated experienceand improvements will compensate in future for the present extra attention.

11.8 Optimization of operating conditions

Optimization of the operating conditions is one of the last

cooperative studies

performed by a group that includes process engineers from the plant, theproject team, the engineering company, specialist consultants, and possibly



also the promoters. It will be based on the existing mathematical models andon the additional data collected during the plant’s start up and operation.

The aim of this study is to prepare a

working model

and to leave it withthe plant’s process engineers and managers, who will use it for decisionmaking and for determining the optimum conditions needed to obtain eachof the following goals:

• The lowest production cost per unit of product, at different levels ofoverall production obtainable in the present plant or for differentoptions of raw materials, with no restriction in supply or sales. Apartfrom the straight costing aspects, the different scenarios may involvedifferent recoveries and different waste disposal costs, etc.

• The maximum production rate obtainable in the present plant fordifferent options of raw materials, and the associated costs (in-creasing production could reach a minimum unit cost and thenrise again).

• The maximum overall profit obtainable in the present plant, consis-tent with the other restrictions of the corporate strategy, with norestriction in supply or sales.


• It would be prudent to expect that some start-up problems will beencountered that may cause one of the following results: a productof lower quality, a lower recovery, or no production at all, and tomake the necessary mental and organizational preparations to handlethese problems.

• One of the following start-up strategies could reduce the damagecaused by such problems: • Starting at a low production rate in order to make salable prod-

ucts, if possible, then increase gradually.• Allowing a lower-than-expected recovery while starting near the

nominal input of raw materials, if salable “on-spec” products canbe assured at a lower production rate.

• Start up the plant with better, cleaner, and more expensive rawmaterial, to avoid problems caused by impurities and establishthat the whole plant is working satisfactorily. Then, the cheaperimpure raw material can be gradually mixed in increasing pro-portions, with full analytical process control.

• On-off operation.• After start up, the plant management should stabilize production at

some level, consistent with the plant’s present capabilities (somephysical bottleneck may have been identified and a program devisedto correct it), and with the present marketing potential of the products



(it was probably anticipated that the full marketing volume wouldbe realized in the first year).

• Optimization of operating conditions should be one of the last coop-erative studies performed by the plant’s process engineers, projectteam, engineering company, specialist consultants, and promoters.The aim of this study, based on the existing mathematical modelsand on the additional data collected from the plant’s operation,should be to prepare a working model, so that the plant’s processengineers and managers can use it for determining the optimumconditions and for operating decisions.

• The project manager must be able to report that the plant is capableof performing its anticipated functions, in nominal quantities andquality. An often-used solution is a carefully organized 24-hour“demonstration run” in which the whole plant is operated underfavorable conditions and with everybody fully mobilized to assist. Itis rightly claimed that the accumulated experience and improve-ments will compensate in future for this extra attention.



chapter 12

Consolidation of the new know-how

12.1 Updating the process know-how

The new specific process know-how, which typically has been developedthroughout the project outlined in this book, represents a valuable asset ofthe corporation that can be used again and again in different frameworks.

Surprisingly enough, this fundamental fact is not always realized.

In many cases,the higher levels of corporate management appear to be content that this oneplant is finally working and leaves the “technical details” of how to managethis specific process know-how to the plant supervisor. Needless to say, in thefirst few years, the attention of this manager will be highly focused on theimmediate problems in his production, product, and market segment. A fewyears later, when it may be necessary to improve and enlarge this plant, withprobably a new managing staff in charge,

this basic know-how could be missing.

On the basis of past experience, it is highly recommended that all thetime and resources necessary for the consolidation of the new know-how beinvested during

the first year after the start-up

. This consolidation can be doneeffectively under the project manager, as his or her last task before beingtransferred from this function, before the members of the project team aredispersed and their attention become occupied elsewhere. This consolidationcan be done in parallel by the different functional groups and then reviewedby all concerned.

The documents resulting from this effort would then be entrusted to thecorporate or divisional technical manager function (which may have differ-ent titles in different corporations). These documents will consist of:

• Updating the process package and operational manual• Analysis of feedback comments from users of the products• Review of any new publications or information on the competition• Review of the need for additional patent applications and initiation

of controlled publication on the new process, products, and plant



12.2 Final revision of the Process Package

The initial process package, as described in detail in Appendix 1, was pre-pared and reviewed to be the essential basis for “freezing” the design of theplant. This process package was then further revised two or three timesduring the detailed engineering work, under the project manager’s leader-ship. The

final revision/consolidation

will incorporate all that was learned fromthe plant’s construction and from operation, up to a certain date.

The principle of the process package remains, but it is expanded toinclude

all decisions

that could affect the process operation. Results reportedshould, as far as possible, be based on all the known facts and on the bestanalysis of all the people who were concerned with the process development,plant design, equipment design, plant operation, and maintenance. There-fore, updating the process package is necessary whenever significant addi-tional facts and experience have been collected.

The typical definition of “black-box”

objectives may remain, unless somechanges have been introduced in the definition of the raw materials or ofthe products, or in the acceptable recovery, as a result of the optimizationstudy described in Chapter 11, or as a response to feedback from the market.

The final division into functional sections may reflect the practical expe-rience accumulated during the start-up, as embodied in a

revised block diagram

and in the definitions of the functional sections, interconnecting streams,recycles, closed loops, buffering, etc.

The separate discussions for each of the sections may be based on thelast revision of the process flow-sheet, of the practical ranges of the vari-ables in the plant’s operating practice, and on the evaluation of the ade-quacy of the chosen design data, with specific recommendation for futureR&D, if necessary.

The updated material and heat balances, tables, and modeling calcula-tions may now be based on new correlation from the plant’s logbooks (orga-nizing the daily data and records).

A critical analysis may be prepared of the original choices, consider-ations, and preferences for the major equipment and packages, of the work-ing relations with the suppliers, and of the actual results and learning fromthe plant’s operation. This critical review will also extend to the issues of“materials of construction,” with the options for “least expensive but reli-able” choices and the observations after the first year of service in the plant.

Original considerations on issues of safety will be reviewed and thepractical plant experience of the first year on the subject will also be included.

The actual requirements for the different services will be updated asshown in the plant’s actual experience (options, source, cost).

12.3 Updating the Operational Manual

For the first implementation of a new process, the first draft of the operationalmanual was prepared and reviewed with the first

P&ID drawings. Further



revisions of the operational manual were reviewed with successive revisionsof the P&ID drawings. During the training period of the operating staff, furtherclarifications were probably introduced in this manual, in response to the que-ries by the new members of staff, each of them arriving with his own back-ground and understanding level and representing a different point of view.

During the start-up, this operational manual was put to the “acid test.” Inmost cases, changes have been

proposed by the operating staff, some of thesederiving from necessity (such as the acceptable human speed of response) andothers motivated by the convenience of the people who will have to live withit, day in, day out. The impact of these proposed changes on the expected processresults should be evaluated independently, then incorporated, if possible, in thefinal revision of the manual that will be enforced by the plant manager.

These changes will also be included in the revised process know-how,which will describe in detail, step by step, how the plant has been operatedand controlled, from its empty start to steady state, including the problemsencountered, their diagnostics and their remedy, and the plant’s occasionalstoppage. This manual will also include all the practiced safety instructionsand the periodical and routine maintenance jobs. The cost of its final editingshould be properly budgeted.

12.4 Feedback from users in the market

The revised process know-how should also incorporate results from thefirst year of marketing, which could affect the process conditions and theplant’s operation.

The project was started on the basis of specifications for products thatwere already on the market, or on changes that

should be

preferred by theclients, or on responses from market surveys done with samples of theintended products. As the production has stabilized and the products areactually sold, there would be a steady feedback of response from the users,which is relayed through the marketing channels.

This information should be carefully analyzed and coordinated with theoptimization studies described in Chapter 11. Such analyses could promptshort-term action, if needed, or define the desirable medium- to long-termtrends for a follow-up program. This task should be part of the know-howconsolidation program.

12.5 Additional patent applications

At this point, the original patent applications on the new process haveprobably been granted and released for publication. The project’s teamshould now consider carefully if the experience of the plant’s design andoperation have revealed any additional

novel

aspect.If this novel aspect appears to be essential or favorable to the application

of the new process, even if it is only quantitative (such as some specificoptimum ranges of operating conditions), it could be covered by an addi-



tional patent application. A new application could also enlarge the circle ofprocess inventors and could allow giving public credit to the outstandingcontributions of certain participating professionals.

12.6 New publications

12.6.1 Information on the competition

As mentioned before, if there is a market demand for a particular product,there would also be, most probably, some potential competition. This com-petition was specifically identified as part of the initial project presentation.An information program was put in place, under the project manager, tocollect all relevant details about the activities of those competitors, eitherfrom open publications (papers or patents), or through the trade “gossip”channels in the market.

The distribution of the products from the new plant, and possibly alsothe publication of the original patents, represent step-changes that will prob-ably cause some response from the competition, which should be monitoredand evaluated. With the stabilization of the plant’s operation, this aspectshould be recapitulated and analyzed, then added for future reference to theknow-how consolidation program.

12.6.2 Publications on the new process and plant

With the publication of the original patent, and actual production from thenew plant, the need for secrecy has changed, although there are operatingdetails that are still kept confidential. Generally, the suppliers of the equip-ment packages cannot also be prevented from publicizing their contributionto the plant as a positive reference.

The public image of the corporation would probably also benefit froman organized program of publications glorifying the successful pioneeringeffort of the new development. The public credit can also be extended todifferent individuals and this personal gratification would generally be veryimportant to them.

12.7 How can this accumulated specific know-how be used again?

The circumstances in which the corporation (or its global partners) couldpossibly profitably reuse the accumulated specific process know-how shouldalso be analyzed and detailed in this consolidation effort. Such potentialcircumstances could be in one or more of the forms described below (seealso Chapter 8).

1.

Increasing the production volume at the same site,

in order

to match demandfrom developing

markets. Expansion of 10 to 30% within the first few



years is normally attainable with the existing resources, on the basis ofthis know-how consolidation. Sophisticated engineering will also berequired, probably by the same company, for the de-bottlenecking ofthe process and the equipment, with the addition of small marginalequipment and clever utilization of the built-in reserves.

2.

Future “repeat” plant(s) in another location or country

, on the basis ofthe operating experience learned in the first plant, as consolidated inthe available package. Generally, this repeat project will not be a merecopy, but it may require some extensive design change for adaptationto the new local conditions and possibly to different raw materialsand services. This design effort will be based mostly on the know-how consolidation, but it may probably also include new “ideas” onhow to improve the process and/or the product, which could not berealized in the presently operating plant.

3.

Adaptation of the novel process technology

developed in this case tosimilar new products. For example, there is a whole range of organiccarboxylic acids with similar chemical properties. The study of theiruse started from those that are more common and could be extractedfrom natural vegetation or simple fermentation. The development ofbiotechnology is expanding rapidly and more such acids can beproduced industrially in fermentation broth. The downstream puri-fication processes can use the same general principles, although theywill have to be adapted to the reactivity of each particular compound.A group with access to a proven technology for one acid has avaluable starting base for development of similar processes.

4.

Synergetic effects

between the new plant and some other existing orplanned industrial facilities of the corporation, in order to

use and/orupgrade the value of a by-product or waste stream

. Typical examples are:• Recovery and use of acids from waste streams or gaseous effluents

instead of neutralizing them• Conversion of organic wastes into animal-feed products• Utilization of gypsum waste from different processes for produc-

tion of cement or other building materials• Separation of sweeteners for human consumption out of indus-

trial molasses• Use of concentrated thermal energy, instead of dispersing it into

the surroundings5.

Synergetic effects

from making use of eventual

idle production capacity

in certain of the corporation’s operations, available developed land,roads, warehouses and similar facilities, in packaging or utilitiesgeneration, and for exploiting the significant cost advantage of largerinstallations.

6. Participation in a combined marketing effort to the same users.For example, in many markets,

the users need a number of dif-ferent products, and it is convenient for them to purchase themalready mixed in the correct form, and this form may be also



profitable for the marketing corporation. Such products could bein compound fertilizers, herbicides, fungicides, animal feed sup-plements, etc. If the products from the new plant are incorporatedinto this kind of marketing effort, this will probably require achange in some of the production steps, to adapt its final form tothe combined mixed package.

12.8 A final note: what have we learned?

“If we had to do it again, we would…”

As has been shown in this book, the development and implementation of anew process is a rather

complex endeavor

, involving many people, a largenumber of decisions, and many unavoidable compromises.

It should be quite normal, at least to the inquisitive scientific minds ofthe team’s leaders and eager younger professionals, that

some

of these deci-sions and compromises may be seen in retrospective as

inappropriate choices

in the light of their less than satisfactory results. The public, objective analysisof such “errors” could teach interesting lessons to all concerned, and preparethem for higher achievements in their next jobs. The problem is that, in theinternal politics of (most?) corporations, there seems to be no place for anyanalysis of this type. In “real life,” one is generally expected to

glorify thesuccess and bury/forget any mistake

.From the personal experience of this author, every one of these profes-

sionals would gain by summarizing at the end of each project, at least in hisown papers and for his own learning and conclusions (and for those aroundhim whom he could trust), the question: if we had to do it again, which taskswould we do differently (or at least try to)?

It is hoped that the personal notes and checklists included in this bookwill facilitate such self-examination.


• Past experience indicates that it is worthwhile to invest the time andresources needed for the consolidation of the new know-how, duringthe first year after the start up.

• During the start-up, the operational manual was put to the acid test.Changes proposed by the operating staff were derived from necessityor motivated by the convenience of the people who will have to livewith it, day in, day out. Their impact on the expected process resultsshould be evaluated independently.

• The distribution of the products from the new plant and the publi-cation of the original patents represent step-changes and the responsefrom the competition should be monitored.



• The accumulated specific process know-how could be used againprofitably in the following frameworks: increasing the productionvolume at the same site; future “repeat” plant in another location;adaptation of the novel process technology to similar new products.

• Synergetic effects between the new plant and other existing orplanned industrial facilities of the corporation may be used for up-grading the value of a by product or waste stream or to utilize idleproduction capacity and available facilities.

• Every professional would gain by summarizing at the end of eachproject the question: if we had to do it again, what would we dodifferently (or at least try to)?



appendix 1

Typical organization and contents of a Process Package

A1.1 General

This appendix is a detailed development of the concepts presented in Chap-ter 10. The typical process package described below should be prepared andreviewed by the process development group. After approval by the projectmanager, it is transmitted to the engineering company, the operating group,and to anybody else concerned, as the essential basis for the design of theplant. This procedure is often called the “freezing” of the process anddetailed verbal explanations and discussions accompany it. Some engineersfrom the process department of the engineering company may have partic-ipated in the preparation of the process package as consultants or serviceproviders.

The principle of the process package is that, as far as possible, importantprocess items should not be decided under the day-to-day pressure of a largeproject. All the decisions that could affect the process operation and resultsshould be well thought out by all the professionals who were concernedwith the process development and the project definition and who should bewell aware of the possible implications of such decisions. Of course, therewill always be changes and surprises and the need to consult further onspecific points but, in general, with the distribution of the approved processpackage, the engineering design and plant preparation can proceed.

The typical content of a process package described below should beconsidered more as a checklist, to be adapted to each project. Particular casesor local situations may be different and justify a different content, withomissions and additions.

The usual procedure is that an experienced engineering company, whenstarting a new project, presents to the client’s project manager for approval,all their usual engineering “design criteria” for civil, mechanical, electrical,instrumentation, material handling, etc. that they propose to use in theirdetailed design. All these decisions may be seen as trivial to the process

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group, but some could be very substantial budget-wise. The review andapproval of all these takes a lot of time and could well distract the attentionof the project management from the process issues. Therefore, it is importantthat the process package should be prepared and approved well in advance.

A1.2 Definition of “black box” objectives

The “black box” representation (see a typical example in Figure 10.3) is avery useful tool, which defines the streams going into the plant (raw mate-rials, streams and services from adjacent plants, chemicals and additives)and the streams exiting from the plant (products, waste streams, gaseousemissions). In other words, this is a definition of

what is done

inside the “blackbox,” without describing

how it is done

. Why is it important?First, the “black box” representation allows accurate description of the

nature and extent of the project to people who need not be concerned withthe “technical details” (such as those in higher corporate management levels:financial, purchasing, and marketing managers), or to persons who are notallowed access to the confidential aspects of the novel process (outside publicor statutory authorities). In addition, this has been found to be a goodintroduction for personnel who will have to study the new process and workon the new plant. It gives them an overall view of what is involved and ofthe basic material changes, before they get too confused with the details.

The definition of all the streams in and out of the “black box” shouldinclude all the

significant components

on a weight basis and in weight per-centage. These figures derive directly from the design basis of the plant, asthis has been formally defined, or on an arbitrary round basis if the designbasis of the plant has not yet been finalized. This data also allows therecipients to become familiarized with the orders of magnitude and to relateto the main components and traces of impurities that could be critical. It alsoprovides for a quick check of the overall material balance; it is surprisinghow many errors have been discovered at this stage, due to inconsistencyin the basic assumptions made by different people at the various points oftheir interactions while the project was put together.

The

essential quality requirements

for each of the product streams shouldbe discussed in detail at this point, since this is one of the main objectivesto be achieved. These requirements could be in the chemical composition(main components or maximum levels of specific impurities) or physicalproperties (color of solution, crystal size, solid microstructure), or even thefinal packaging. The importance of each of these items for marketing andsales should be emphasized and understood.

The possible options and variations (random or seasonal) in the sourceof each of the raw materials and of any fuel used should also be discussed,to explain or justify the choice made in the basis of design. In many industrialcases, important parameters in the raw materials composition change in thetwo to three years that may have passed between the process freeze and theplant start-up.

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The detailed description of each of the waste streams (if any), as it leavesthe plant, after any compulsory waste treatment included in the plant’sscope, should be an important part of the process package. The temporarylevel of objectionable impurities in such streams may possibly jump byorders of magnitude due to operational errors, and such fluctuations shouldbe evaluated and taken into account. There should be at least one acceptableform of disposal of each of the waste streams. If there are several disposaloptions, the final choice is a matter to be worked out by the project teamduring the detailed engineering phase, in relation to the local conditions andregulations and to the associated costs.

A1.3 Division of the process into sections as illustrated in a block diagram

The next step in the preparation of the process package is the division of the“black box” into

functional sections

, connected by numbered streams. Thesedifferent sections and interconnecting streams can be usefully representedin a

block diagram

(see typical example in Figure 5.1).

Each section is alsogiven a formal name, defining its prevailing chemical mechanism (i.e.,gas–liquid reaction, liquid–liquid extraction, evaporation, crystallization,drying, etc.). These formal names will be used in all the project documentsand later by the plant staff for many years, so one should think carefullybefore freezing them.

The exact definition of each section is important for efficient processdesign, but this can be complex, as there may be different acceptable divisions.In any case, a careful analysis is needed to arrive at a reasonable number ofsections, as many people may have to work with these definitions for manyyears. In this context, a section is a definite part of the process in which theflow-rates and compositions of the exit streams are determined uniquely by:

• The flow-rates and compositions of the entering streams• The operating conditions controlled by the operator (i.e., the temper-

ature, pressure, residence time, reflux ratio, circulation velocities, etc.)

Process streams do not always pass from one section to another in aforward direction only. In many equilibrium-controlled processes, there aregreat advantages to recycling some streams in the backward direction, andsometimes this is an absolute necessity. A well-known example of this prin-ciple is the reflux stream from the condenser to the top of the rectifica-tion/distillation column, but the same principle can be applied effectivelyto most equilibrium-controlled processes. The exact return point of eachrecycle stream could be critical and could determine whether there needs tobe division into more sections.

In certain other processes, the “black box” does include an internalstream circulating between the different sections, which hardly gets outside,



except for unwanted losses. This is typical, for example, in solvent extractionprocesses, in which a relatively large solvent stream circulates in a closedloop. Other examples are the mercury loop in a chlorine-soda plant and themother-liquor loop in a salt purification plant.

A buffering tank volume may be needed for averaging the fluctuationsof certain streams passing from one section to another. In semibatch pro-cesses, which, despite their old-fashioned connotations, are still necessaryand useful in specific cases, some of the sections fluctuate on-off and requirebuffering “before and after,” so that the other sections can be operatedcontinuously, in more or less steady state. In some other processes, thecomposition of a raw material may fluctuate and despite all process controlefforts, the output streams from certain sections receiving such raw materialneed to be blended and averaged before proceeding.

All these aspects should be discussed explicitly at this stage of theprocess package preparation, in connection to the block diagram, to bridgebetween the theoretical steady-state ideal and the real-life necessities.

A1.4 Separate discussions for each section

4.1 There should be a

detailed description

of the prevailing conditions,successive and overall chemical reactions, and the physical changesor separations obtained, with particular emphasis on the criticalitems. In this description, it is important to convey exactly:• How each of these reactions or separations is controlled• Which are the controlling parameters (for example, temperature,

pressure, reactant ratio, velocity, residence time)• How a change in the magnitude of any of the controlling param-

eters would affect the final result4.2 A

process flow-sheet

drawing, which is the most recent “frozen” revi-sion of the preliminary flow-sheet discussed in Chapter 6 , with allthe numbered equipment, pipes, valves, and instruments essentialfor the understanding of the operation of the section. This processflow-sheet drawing is the

translation

of the process block diagram(referred to above) and the chemical mechanisms concepts into theusual chemical engineering methodology and into the chemicalplant’s practice. This document should be clear also to the “non-chemical” engineers and technicians who will be working on thedetailed design and plant construction and should include also thesystematic tag-numbering of all pieces of equipment and all mainstreams, which will then be used as references for all future work.

4.3 A list of all the

operating variables

, which can be controlled by theoperator in order to obtain the desired results.

4.4 Any design data available, from tests, publications, or internal cor-relation, on the process behavior or equipment operation. This de-sign data should also include the physical properties of each stream



(specific gravity, specific heat, viscosity, vapor pressure) in the spe-cific operating conditions and the kinetics of the reaction as a func-tion of the operating variables.

A1.5 Material and heat balances

5.1 Following the discussion of the process design for all the sections,any

modeling

that may have already been done should be presentedand discussed, together with all assumptions and data sources. Ide-ally, a computer model is available and can be readily used to deliverreliable tabulated material and heat balances. But generally for a newprocess under development as discussed above, the preparation ofsuch a model is generally not of the highest priority and it may beavailable only if, by chance, a modeling specialist is on the team.

5.2

Preliminary material and heat balances

of all the significant componentsin all the streams should be prepared on spreadsheets by the usualtrial-and-error methods, and included in the process package (togeth-er with all assumptions and data sources), clearly marked as “pre-liminary” and placed “on hold” (in the professional jargon). It is veryimportant to emphasize that, due to the possible gap in the transferof the project’s working leadership from the promoters to the engi-neering company, the inclusion of such numerical tables in the pro-cess package should be considered

for illustration purposes mainly

. Itwill be the responsibility of the engineering company, and one oftheir first tasks, to check and confirm the numerical accuracy of thesetables before making further use of them. The process modelingeffort, which is no longer on the critical path, should then be contin-ued

either by the engineering company (if it is within the scope oftheir contract), or by a specialist consultant. The resulting compre-hensive model will be used later in the final optimization of theprocess operation.

A1.6 Equipment choices

6.1 A preliminary list of all major pieces of equipment, with their tag-number, formal name, budget installed cost, and possible suppliers,should be prepared on a suitable spreadsheet and included in theprocess package (see typical example in Table 7.4). This preliminaryequipment list is a very important working tool, which is startedby the development team on the basis of the different sections ofthe process flow-sheet, but which will have to be worked out bythe engineering company in many formats for many purposes:• For different

types

of equipment• For different

suppliers



• For different geographical

areas

in the plant• For

piping

connections• For different

materials

of construction• As a basis for the investment

cost sheet

• To sum-up the

electrical drives

, etc. Note in this regard that aseparate list should be started for those electrical consumers thatneed to be connected to the electrical emergency supply, as thisinformation becomes available.

6.2 The preliminary selection of the type, model, and sizing of each

majorpiece of equipment

should be presented in the process package, basedon a

functional analysis

as quantified in the average material balances.A specification sheet would be opened for each major piece of equip-ment, in which this selection should be recorded, together with allthe facts related to its function, a detailed explanation of all the

possible options

for its type, model, size, and any other importantspecification item, for the selection of the materials of construction,and the estimated electrical requirement, and the

reasons

for the rec-ommended choice.

6.3 A preliminary list of

potential suppliers

for the recommended equip-ment type. This list is by no means exhaustive at this stage. In certaincases, when only one

preferred supplier

can be recommended for amajor piece of equipment, the situation will be simplified but alsomore complicated: this creates a critical dependence and many cor-porations are opposed to such a situation, as a matter of principle.

6.4 In certain cases, the new process may require the development anddesign of a

new or modified

type of reactor or separator that cannotbe procured readily from an established supplier. This requirementhas been identified before, but has constituted an additional load onthe development effort and has possibly already been dealt in a pilotprogram. In this case, a large part of the process package should bedevoted to the analysis of:• The function of the new equipment• The pilot results• The design principles• The sizing calculations • The exact recommendations for the final industrial design

6.5 As an additional result of this presentation of the major equipment,the plant space needed for the recommended choices (area andheight) can be indicated for the

preliminary layout

studies.

A1.7 Services

7.1 These services are

essential and major cost factors

, although they areoften considered by the R&D scientists as trivial. The options avail-able for each service are not basically different for a new process



than for a conventional one. However, the choices and the optionsare much wider before the “freezing” of the novel process and/orof the implementation site. Those generally needed in most chem-ical plants are:•

Electricity

for drives and sometimes also for heating• Cooling water•

Saturated steam

at several pressures (live or condensing)• Compressed air•

Fuel

of different kinds• Occasionally, heating oil, nitrogen and/or oxygen are also neededOptimization studies to achieve the cheapest, most convenient solu-tion could make a

decisive difference

for the economic value of the newprocess. Often the development team is able to start such studies butnot complete them, as the economic factors have not been clarifiedbefore the process package is presented. If there still are attractiveprospects, these should be described clearly in the process package.

7.2 The

nominal consumption rate

of each service needed for

steady-stateoperation

can be calculated directly from the material and heat bal-ances presented above, and from the equipment list in the previoussection for the electrical power. Those

average

consumption rates areused for the (annual-basis) economic calculations, but higher

design

quantities should be provided to cover the instantaneous rates (i.e.,for starting or stopping, or for emergencies). The process packagecan only provide general guidance on these design quantities, andthey may only be finalized after all the detailed information is ob-tained from the various equipment suppliers. So, one of the firstassumptions (placed on “hold”) in the detailed process engineeringwould relate the maximum delivery rate needed for each service.These assumptions are generally based on past experience and theintuition of the leading process engineer, but they should be con-firmed as soon of possible so that the services supply can be finalized.

7.3

Fuel

could be needed

either for direct use in a combustion deviceincorporated into the process, or for the dedicated production ofsteam or other heating medium in the new plant. Several types andqualities of fuel can be considered, including coal, liquid petroleumfractions, or natural methane gas. In addition to the obvious consid-erations of delivery cost and convenience, a decisive factor in thechoice of fuel will be the impurities in the flue gases discharged fromthe stack (SO

2

/SO

3

, nitric oxides, metallic dust, and so on) and/orof fly-ashes. If local ecological restrictions require intensive cleaninginstallations, this may cancel the advantages of a cheaper fuel.

7.4 Condensable saturated

steam

(at different pressures), or another heat-ing medium (

oil

) is used in heat exchangers. In some cases, it maybe purchased from the site’s central services, or from an adjacentproducer. If not, a steam system should be installed with all theancillaries, such as the production of boiler-feed water. In many cases,



when large quantities of lower temperature heating are needed, therecould be a decisive advantage in a synergetic combination with aplant that has a large excess of waste heat. This is of course in additionto any possible internal saving, for example by the use of multiple-effects evaporators or vapor recompression.

7.5

Cooling water

is generally produced in the new plant’s own coolingtower. The

minimum supply temperature

(usually of the order of 26 to30

°

C) depends on the climatic conditions of the location, and it couldbe an

important limitation in the basic design of the process

.

For example,in many processes that include large-scale evaporation and conden-sation under vacuum, if the cooling water is not “cold” enough, itbecomes necessary to use much more expensive, artificially chilledwater, and this can make a significant difference.

It may sometimesbe received from a nearby sea or river at a lower temperature andthis can be an important asset.

7.6

Electricity

is generally purchased, unless the new demand will be largeenough to justify the purchase of a generator. Even then, a back-upconnection to the external grid will generally be needed. Some pro-cesses also require an

emergency

source of electric power for safety ordamage control, as mentioned in Section A1.9 below, on safety issues.

7.7

Process water

is used in all plants in relatively small quantities andin many different specifications (quality, purity). Generally this sup-ply is not a significant consideration, but it could become very sig-nificant in certain hydrometallurgical or mineral projects, and indesert areas. In most plants, a

fire-fighting

water supply and rig mustalso be supplied from a reliable source, with an adequate back-up tomeet possible emergencies.

7.8

Compressed air

is generally produced in the new plant at differentsupply pressures. A small quantity is handled separately for pneu-matic control at assured pressures, but the larger quantities are gen-erally at a lower supply pressure for large aerobic fermentors, airmixing of pulps, direct-contact drying in closed vessels, etc. In certainprocesses, it could be a major consumption and production cost.

7.9

Oxygen

and/or nitrogen as

inert gas

, if needed, can be purchased incertain cases, or produced on site by an air separation installation.

A1.8 Materials of construction: options and preferences

The choice of the materials of construction that are in direct contact with eachof the process streams, which must resist any corrosion or erosion action, canbe critical to assure a long plant life. A large choice of sophisticated materialsis now available, i.e., different kinds of metallic alloys, polymers, glass, ceram-ics, refractory bricks, etc. One of the main considerations is that some of thesematerials are quite expensive and involve a large investment.

Options for each of the streams should be indicated in the process package,together with any relevant factual information (previous experience, tests, and



expert’s recommendations). However, the choice of the “least-expensive-but-reliable” option should be an essential part of the project manager’s respon-sibility and this should be indicated clearly in the process package, even inthose cases when it may be considered trivial and well known.

Should there be any doubt on choice of construction material for aparticular stream at the time of reviewing the process package, this reserva-tion should be indicated (“hold”). Thus, the engineering company will notmake any binding commitment on this item, until it is further clarified andconfirmed with experts or by corrosion tests, and the “hold” removed bythe process manager.

A1.9 Safety aspects

Those who work in the chemical industry routinely encounter potentialsafety hazards, including fire, explosion, burning, poisoning, radioactivity,thermal or visual radiation, and air or water contamination.

Nevertheless, it is the

responsibility of the process developers to indicateclearly

in the process package if there could be new or unusual hazardsin the novel process. They should also provide any available data relevantto the evaluation of the extent of the known safety hazards, such as dataon the ignition point, flash point, explosive ratio, volatile components orgaseous emissions, poisonous or carcinogenic effect on humans, for dif-ferent streams.

Engineering companies that design chemical plants are generally expe-rienced and have their own experts in this field. The design and specificationof the provisions needed for preventing such hazards (whether “conven-tional” or emphasized in the process package) in the new plant, and even-tually for controlling them, is a

definite part of the detailed engineering work

.This work may be guided by specialist consultants, within the frameworkof external statutory regulations and insurance requirements. This specifica-tion is also generally linked to the ecological permitting procedures in effectin the particular area.



appendix 2

Functional organization structure of a typical development project

A2.1 Successive stages

The functional organization structure of a typical process developmentproject is critically important, but is also

complex and constantly evolving

,depending on local and personal circumstances. For that reason, this orga-nization has been, more often than not, left to the “play of forces” or tothe wisdom of the manager in charge, and the results may or may not havebeen effective.

This appendix considers the

objective

demands on the organization, inorder to increase its chances of success. The resources discussed in Chapters2 and 3 are organized here in a more conventional hierarchic structure, inwhich every leader is responsible for four to six functions.

In this regard, one should recognize the basic differences in the threemain stages of the project, as these relate to the demands on the organization.

1.1 The

invention and promotion stage

, which may have one of two con-texts, depending on whether:• It is done

inside

the implementing corporation, in its R&D depart-ment or “new business” department, on the basis of the corpora-tion’s already established position in the field and of its accumu-lated know-how

• It is done by

external

promoters, prompted by published informa-tion about the potential need for such process, and possibly alsoby their desire to promote sales of new technology, equipment,or services

1.2 The

process development stage

, with the financial support of a corpo-ration and under a designated project manager, until a decision isreached to build a plant



1.3 The

construction and running-in

of the plant, under the project man-ager, until the responsibility is transferred to the plant manager

A2.2 The invention and promotion stage

See Figure A2.1.

2.1 The inventors (there are usually two or three co-inventors) or corpo-rate R&D scientists have generally limited executive resources oftheir own, and they typically form collaborative links with promot-ers, which can take different organizational forms, depending onlocal conditions and personalities. From the working organization’spoint of view at this stage, the inventors should be controlling thefollowing functions: the literature and patent search, the processengineers, and the laboratory feasibility tests. They should also be inworking contact with the patent attorney.

2.2 The

promoters, or the corporate managers in charge of R&D or “newbusiness

” have the function of defining a favorable implementation

Figure A2.1

Invention and promotion stage.

inventors promoters

processengineering

consulting andcosting

engineering

businessconsultant

feasibility lab.tests

patentattorney

negotiation and agreementwith corporation

lawyers

literature and patent search



scheme, contacting the corporation at the suitable level, promotingand negotiating an agreement concerning the development program.They have to prepare the proposal in a presentable and attractiveform, on the basis of the information relayed by the inventors. Theywill be using for that purpose specialist consultants, costing engi-neers, business advisers, agents, and lawyers.

2.3 At this stage, an exploratory

literature and patent search

begins usingmaterial already on file, probably performed by the inventors’ assis-tants in an academic library and on internet data bases, with trial-and-error and direct feedback. This exploratory work could also besubcontracted, i.e., to graduate students. Many patent attorneys arealso organized to supply such services at affordable rates. In any case,the analysis of the results from this search will require the personalattention of the inventors.

2.4

Preliminary feasibility tests

are very important and are generally doneunder the direct supervision of the inventors, first, to reassure the in-ventors that they are working on a reasonably firm basis, then to supplyconcrete exploratory results to be compared to the expected/predictedresults. In addition these preliminary tests will provide observations onthe behavior of the reacting and resulting phases. In many cases, suchtests may have to repeated later, as a demonstration to the delegates ofthe prospective implementing corporation, so that special attention isoften devoted to obtain a show-case impressive format.

2.5

Engineering consultants

advise the inventors and promoters of whatcan and cannot be done in the way of implementing the new process.This input can have a critical effect on the focusing of the basicfeatures of the new process. Then, the engineering consultants willprepare the

preliminary

process definition and flow-sheet, the basicbalances and cost estimates, and will present these in a preliminaryengineering report, in an acceptable and “friendly” format, whichwill be used by the promoters in their future presentations.

2.6 The

patent attorney

is either a free practitioner or a full-time employeeof the organization connected to the inventors/promoters. At thisstage, he or she will advise the inventors and promoters about theprocedure and the wording of the first patent application, and file itwith the patent office. In later stages of the project, the patent attorneywill help to formulate the scientific aspects of the claims.

2.7 There are business consultants who specialize in selling and buyingindustrial intellectual properties. They advise the inventors and pro-moters about the acceptable procedure and the criteria for selectingand contacting a prospective corporation, which may be interestedin the new development. In many cases, they also provide personalintroductions from their previous records. They will also prepare a

preliminary

economic and market analysis, in a conventional format,and (hopefully) with attractive bottom lines, which shall be used bythe promoters in their presentations.



A2.3 The process development stage

See Figure A2.2.

3.1 The

project manager

is nominated by, and reports to, the corporation’srelevant manager. Apart from his executive assistants, he should indirect working contact with the inventors/promoters, and in directcontrol of the leaders of the following functions :• Engineering deputy• Senior process engineer• Know-how management• Marketing specialist• Coordination with site management

3.2 The

inventors/promoters

continue to participate in the project’s coreteam on a consulting basis, making their basic know-how available,mainly for the experimental program. Their main daily contacts arewith the senior process engineer and with the “know-how manage-ment” function (see below).

3.3 The

engineering deputy

of the project manager (in fact “number two”on the team) manages the following functions (see Figure A2.3):•

Cost engineer

,

in direct daily contact, who also handles the engi-neering files and contacts with outside suppliers

Figure A2.2

Process development stage I.

project manager inventors/ promoters

engineeringdeputy

marketingspecialist

corporation management and services

coordinationwith site

management

seniorprocessengineer

know-howmanagement

see Figure A2.3 see Figure A2.4

see Figure A2.5



•

Plant operation specialist

,

generally a part-time job,

who is coordi-nating all issues related to the future plant’s operation, staffing,and safety procedure, and should be coordinating efforts to findacceptable solutions

•

Plant safety expert

,

also

a part-time job, possibly an externalconsultant

•

Economic studies and analysis

, possibly with the participation ofanother corporate department and/or of an engineering companyand based on the input of the market specialist

•

Designers and/or suppliers of major equipment

,

who provide the nec-essary information before any formal bidding, and participate inpiloting.

3.4 The

senior process engineer , working in direct contact with the projectmanager and the inventors/promoters, and managing the followingfunctions (see Figure A2.4):• Process engineers — a number of full-time process engineers who

prepare the process flow-sheets, studies of alternative options,balance spreadsheets, equipment specifications,

correlation of ex-perimental data,

etc.

Figure A2.3

Process development stage II.

engineering deputy

project manager

costengineer

equipmentdesigners/suppliers

economicstudies and

analysismarket specialist

plantoperationspecialist

plant safetyexpert



•

Process modeling specialist

— who prepares and updates the math-ematical model and analyzes the results of various runs.

•

R&D laboratories

— the senior process engineer also managescontracts with the R&D laboratories and coordinates the experi-mental work ordered, by supplying detailed instructions, mate-rials, and additional personnel as needed, in addition to review-ing the reports and approving the accounts.

•

Pilot installations

—

a similar organization relates to contracts forwork ordered with external pilot installations, except that the pro-cess engineers on the project’s team are likely to participate per-sonally and closely in these tests and in the analyses of the results.

•

Corrosion and materials specialist

—

who coordinates the testingand collection of information required for determining the con-struction materials to be used.

3.5 Know-how management (see Figure A2.5): most large corporationshave specialists who can fill this function on a part-time basis. In lesscomplicated cases, this function may be filled by the inventors or bythe senior process engineer. It involves a considerable amount ofpaperwork for the orderly management and up-dating of the intel-lectual propriety, in direct contact with the relevant patent attorneyand publication search specialist.

Figure A2.4

Process development stage III.

senior process engineer

project manager

R&Dlaboratories

pilotinstallations

corrosion andmaterial

specialist

processmodelingspecialist

inventors/promoters

processengineers



3.6 The marketing specialists of the corporation who conducted the fieldtests (see Chapter 9) are expected to report back as soon as possiblewith findings and recommendations concerning the details of theproducts that should preferably be changed, or adapted, in order toget a better sales return or market share. Such feedback is also re-quired for the final economic studies, to confirm the estimated salesrevenue from the products.

3.7 Coordination with site management: if the new plant is erected with-in a larger industrial site owned by the corporation, there should bea lot of coordination with the site management. Generally, this is timewell spent, as the help obtained is of great practical value.

A2.4 The construction and running-in period

All the functions described above in Section A2.3 are continuing during thisperiod, under the project manager, with some changes in emphasis and withthe following additions (see Figure A2.6):

4.1 The

engineering company staff

,

which is doing the detailed plant designand issuing drawings and specifications for approval by the projectmanager or his delegate. This staff is generally drawn from differentdepartments in the engineering company.

4.2 The

construction manager

and his staff manages all the activities re-lated to procurement, construction, equipment erection, etc., and allthe actual contractors on site. While formally under the supervisionof the project manager, the construction manager has generally awide operating authority to organize the work on the site.

4.3. The

new plant manager and operating staff

,

who are trained to receiveand operate the plant in coordination with the existing site manage-ment (see Chapter 11).

Figure A2.5

Know-how management.

know-how management

project manager

patentattorney

inventors/promoters

publicationsearch

specialist



4.4. On the

project team

, the following tasks are emphasized

in this period:

• The process engineers work mainly on checking and coordina-tion of the design and assisting in training and preparation forstart-up.

• Complementary R&D tests may be needed to ascertain certaindetails of the design.

• Cost engineering personnel are still fully occupied with economicstudies and analysis of alternatives (this line of work seems to benever ending).

• Financial coordination and control need to be maintained, accord-ing to the established corporate criteria, with the relevant depart-ments of the owning corporation. This becomes very importantand time-consuming, with the total amount of money spent.

Figure A2.6

Plant construction and running-in stage.

corporation management and services

project manager site management

new plantmanager

new plant staff

senior processengineer

engineeringcompany

constructionmanager



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