Gavin Towler is the Senior Manager of Process Design, Modeling and Equipment at UOP LLC.He manages the areas of process design and optimization, equipment design, and physical and kineticmodeling for UOP Research and Development. As adjunct professor at Northwestern University,

he teaches the chemical engineering senior design classes. He is a Chartered Engineer and Fellow ofthe Institute of Chemical Engineers.

Ray Sinnott began his career in design and development with several major companies, includingDuPont and John Brown. He later joined the Chemical Engineering Department at the University ofWales, Swansea, UK, publishing the rst edition of Chemical Engineering Design in 1983. He is a

Chartered Engineer, Eur. Ing. and Fellow of the Institute of Chemical Engineers.

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Chemical Engineering

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As a Senior Design Course Text book

As an Int roduct or y Chem ical Engineer ing Text book

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Supplem ent ar y Mat er ial

Resources f or Inst ruct ors

ChemicalEnginering Design

Lecture Slides

Image Bank

Inst ructors Manual

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Coed-y-bryn, Wales

Inverness, Illinois

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1 INTRODUCTIONTO DESIGN

Chapt er Cont ent s

1.1. In t roduct ion

1.2. Nat ure of Design

1.3. The Anat om y of a Chem ical Manuf act ur ing Process

1.4. The Organizat ion of a Chem ical Engineer ing Project

1.5. Project Docum ent at ion

1.6. Codes and St andards

1.7. Design Fact ors (Design Margins)

1.8. Syst em s of Unit s

1.9. Opt im izat ion

1.10. Ref erences

1.11. Nom enclat ure

1.12. Prob lem s

Key Learning Objectives

& How design projects are carried out and documented in industry

& Why engineers in industry use codes and standards and build margins into their designs

& How to improve a design using optimization methods

& Why experienced design engineers very rarely use rigorous optimization methods in

industrial practice

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1.1. INTRODUCTION

This chapter is an introduction to the nature and methodology of the design processand its application to the design of chemical manufacturing processes.

1.2. NATURE OF DESIGN

This section is a general discussion of the design process. The subject of this book ischemical engineering design, but the methodology described in this section appliesequally to other branches of engineering.

Chemical engineering has consistently been one of the highest paid engineeringprofessions. There is a demand for chemical engineers in many sectors of industry,including the traditional processing industries: chemicals, polymers, fuels, foods, phar-maceuticals, and paper, as well as other sectors such as electronic materials and devices,consumer products, mining and metals extraction, biomedical implants, and powergeneration.

The reason that companies in such a diverse range of industries value chemicalengineers so highly is the following:

Starting from a vaguely dened problem statement such as a customer need or a set ofexperimental results, chemical engineers can develop an understanding of the importantunderlying physical science relevant to the problem and use this understanding to create aplan of action and set of detailed specications which, if implemented, will lead to apredicted nancial outcome.

The creation of plans and specications and the prediction of the nancial outcomeif the plans were implemented is the activity of chemical engineering design.

Design is a creative activity, and as such can be one of the most rewarding andsatisfying activities undertaken by an engineer. The design does not exist at the start ofthe project. The designer begins with a specic objective or customer need in mindand, by developing and evaluating possible designs, arrives at the best way of achiev-ing that objectivebe it a better chair, a new bridge, or for the chemical engineer,a new chemical product or production process.

When considering possible ways of achieving the objective, the designer will beconstrained by many factors, which will narrow down the number of possible designs.There will rarely be just one possible solution to the problem, just one design. Severalalternative ways of meeting the objective will normally be possible, even several bestdesigns, depending on the nature of the constraints.

These constraints on the possible solutions to a problem in design arise in manyways. Some constraints will be xed and invariable, such as those that arise fromphysical laws, government regulations, and standards. Others will be less rigid andcan be relaxed by the designer as part of the general strategy for seeking the best design.The constraints that are outside the designers inuence can be termed the externalconstraints. These set the outer boundary of possible designs, as shown in Figure 1.1.Within this boundary there will be a number of plausible designs bounded by the other

2 CHAPTER1 INTRODUCTION TO DESIGN