Applied Chemical Process Design

Applied Chemical Process Design

FRANK AERSTIN AND GARY STREET Dow Chemical Midland, Michigan

With a Foreword by

K. D. Timmerhaus

PLENUM PRESS • NEW YORK AND LONDON

Library of Congress Cataloging in Publication Data

Aerstin, Frank. Applied chemical process design.

Includes index. 1. Chemical processes. 2. Chemical engineering. I. Street, Gary, joint

author. II. Title. TP 155.7 .A35 ISBN-13:978-1-4613-3978-6 DOI: 10.1007/978-1-4613-3976-2

First Printing-November 1978 Second Printing - May 1980 Third 'Printing - January 1982 Fourth Printing-October 1989

© 1978 Plenum Press, New York

660.2'81 78-9104 e-ISBN -13 :978-1-4613-3976-2

Softcover reprint of the hardcover 1st edition 1978

A Division of Plenum Publishing Corporation 233 Spring Street, New York, N.Y. 10013

All rights reserved

No part of this book may be reproduced, stored in a retrieYaI system, or transmitted, in any form or by any means electronic, mechanical, photocopying, microfJiming, recording, or otherwise, without written permission from the Publisher

Contents

Foreword ........................................... .

Preface ............................................. .

List of Figures ...................................... .

List of Tables ....................................... .

Conversion Tables ................................... .

1. Agitation and Mixing ................................ . 1.1. Agitators •.••••.•••.•••..••••••.•••••••••••.•..••.. 1.2. Motionless Mixers .•.•.••...•.•.•...•...•..•.•..•••..

2. Cooling Towers ................... ~ ................. .

3. Decanters .......................................... .

4. Distillation .......................................... . 4.1. Basic Laws ••..••••••.••••••.••••••.•••••••••..•••• 4.2. Shortcut Method-Optimum Trays and Optimum

Reflux Ratio •..••••••••••••••.•••••••••••••••••••••. 4.3. Flash Vaporization •..•••..•.•.•.••••••.•.•••.•.•.•.•. 4.4. Selection of Internals •.•••••••••••••••..••••.••.•.•••• 4.5. Tray Column Diameter ••••••••••.•••••••.••••.•••..••• 4.6. Tray Overall Efficiency ••••••.••••••••••••••••••••..••• 4.7. Packed Column Design •••••.••••••••..••••••••.••.••• 4.8. Packed Column Diameter and Pressure Drop ..••.••••.....•

5. Economic Evaluation ................................ .

6. Fluid Flow .......................................... . 6.1. Fluid Flow-Single Phase ••••.•••.••••••.•.•••••••.•••• 6.2. Fluid Flow-Two Phase ••••••••••••••••.•••••••••.•••. 6.3. Flow through Orifices

7. Gas-Solid Separations .................. , ............ .

8. Heat Transfer ....................................... . 8.1. Heat Transfer Coefficients •••••••••.•••..•••••.•••.•••• 8.2. Heat Losses from Tanks •.••..• : .•••.•...••..........•. 8.3. Heating of Process Piping and Vessels-Heat Losses

from Insulated Pipelines •••••..•••.••••.•.•••••••.••••• 8.4. Heating of Process Piping and Vessels-Steam

Tracing •••••.••••••••••.•••.•.•••••••••.•••..••.•.

vii

ix

xi

xv

1 9 9

12 29 35 39 39

39 47 49 49 50 51 53 57 65 65 92 96

105 111 111 121

121

121

V

vi CONTENTS

B.5. Heating of Process Piping and Vessels-Dowtherm SR-1 Tracing ••••••••••.••••••••••••••••••••••••••• 124

B.6. Double Pipe Exchangers •••••••••••••••••••••••••••••• 128 B.7. Shell and Tube Heat Exchangers ...•..•••••.••••.•.•••• 132 B.B. Heat Transfer Coefficient in Agitated Vessels ••••••.•..••. 144 B.9. Falling Film Coefficients ...•....................•...•. 145 B.10. Reboilers and Vaporizers ..••••......••••••..•..••.••• 146 B.11. Condensers ••••••••••.•••••••••••••••••••••••••••• 154 B.12. Air-Cooled Heat Exchangers •••••••••.••••••••••.•••••• 158 B.13. Unsteady-State Heat Transfer ••••••••••••••••••••••••• 170

9. Hydroclones ......................................... 181

10. Materials ............................................ 185

11. Physical Properties ................................... 189

12. Dimensions and Properties of Piping ................... 231

13. Pump Sizing ......................................... 235

14. Safety Relief Valves and Rupture Disks .....•....•..... 243

15. Steam Ejectors for Vacuum Service .................... 257

16. Tank Capacity ........................................ 269

17. Dimensions and Properties of Steel Tubing.... ......... 275

18. Vapor-Liquid Separators .............................. 277

19. Vessel Design ........................................ 283

Index ........................................... 291

Foreword

Development of a new chemical plant or process from concept evaluation to profitable reality is often an enormously complex problem. Generally, a plant-design project moves to completion through a series of stages which may include inception, preliminary evaluation of economics and market, data development for a final design, final economic evaluation, detailed engineering design, procurement, erection, startup, and pro­duction.

The general term plant design includes all of the engineering aspects involved in the development of either a new, modified, or expanded industrial plant. In this context, individuals involved in such work will be making economic evaluations of new processes, designing individual pieces of equipment for the proposed new ventures, or developing a plant layout for coordination of the overall operation. Because of the many design duties encountered, the engineer involved is many times referred to as a design engineer. If the latter specializes in the economic aspects of the design, the individual may be referred to as a cost engineer. On the other hand, if he or she emphasizes the actual design of the equipment and facilities necessary for carrying out the process, the individual may be referred to as a process design engineer. The material presented in this book is intended to aid the latter in developing rapid chemical designs without becoming unduly involved in the often complicated theoretical underpinnings of these useful notes, charts, tables, and equations.

The authors have attempted to emphasize those areas most often encountered in chemical process design, namely heat transfer, mass transfer, fluid flow, and mixing. Other design areas considered, but to a lesser extent, include cooling towers, liquid-liquid separations, gas-solid separations, vapor-liquid separations, pumps, safety valves and rupture disks, steam ejectors, and vessel design. These design procedures are sup­plemented with information on the thermal and transport properties of many materials and chemicals needed in the design of such process equip­ment, the mechanical properties of a host of metals commonly used in their construction, and the dimensions and properties of steel piping and tubing. In addition, two measures of economic profitability have been included to assist the process design engineer in justifying a specific design or process to management.

vii

Preface

Applied Chemical Process Design was prepared to give the chemical process engineer a ready reference that can be used at the office, in the field, or while on business travel.

After spending several years in the chemical industry, we had found that each of us had a rather scattered collection of useful notes, charts, tables, articles, etc. The need to organize and consolidate these references was obvious.

This book has been intentionally kept concise, to maintain its useful­ness while in the field. Theory has been virtually eliminated. However, the material presented is adequate to solve many design and/or plant problems. Those wishing to learn more of the background or theory behind the meth­ods presented should consult the references and selected readings given at the end of each chapter.

The areas given the highest priority are those encountered most often: agitation, distillation, heat transfer, and fluid flow.

The book is intended to help students, process design engineers, pilot plant engineers, and production engineers. It is hoped that it will be of particular value to younger engineers in bridging the gap between theory and application.

Acknowledgments

We would like to express our thanks to our colleagues at Dow Chemical, USA, whose constructive comments have been very helpful. In partic­ular, the help of Lanny Robbins, Bruce Lovelace, Clarence Voelker, James Huff, Gerald Geyer, Douglas Leng, Thomas Tefft, Leo Schick, Jay Bleiweiss, James May, Paul Handt, and Kenneth Coulter has been appreciated. We would also like to thank Dr. James Pfafflin (Stevens Institute of Technol­ogy) and Dr. Harold Donnelly (Wayne State University) for their comments and help. Finally, we would like to thank the department secretaries (Susan Krantz, Erna Nash, Barbara Talicska, Anne Marie Duranczyk, and Nancy Roop), whose patience and perseverance have been greatly appreciated.

Frank Aerstin Gary Street

IX

Figures

Figure 1.1. Tank and agitator dimensions . . . . . . . . . . . . . . . . . . . 10 Figure 1.2. Turbine power correlations .................... 11 Figure 1.3. Power correlations for glassed steel agitators ....... 12 Figure 1.4. "A" factor vs. Reynolds number in the laminar flow

region ..................................... 15 Figure 1.5. "E" factor vs. Reynolds number in the turbulent flow

region ..................................... 15 Figure 1.6. Darcy's friction chart ......................... 17 Figure 1.7. LPD laminar flow ............................ 19 Figure 1.8. ISG laminar flow ............................ 20 Figure 1.9. LPD turbulent flow .......................... 21 Figure 1.10. ISG turbulent flow ........................... 22 Figure 1.11. Parameters for pressure drop in liquid-gas flow ..... 23 Figure 2.1. Cooling tower performance curves ............... 30 Figure 2.2. Induced draft cooling tower sizing curve .......... 31 Figure 2.3. Typical parts and framing for a crossflow cooling

tower ..................................... 32 Figure 3.1. Decanter piping ............................. 36 Figure 3.2. Sizing discharge piping from gravity decanters ...... 36 Figure 3.3. Liquid-liquid gravity decanter with circular overflow

weirs and adjustable interface position ............ 37 Figure 4.1. Fenske equation for minimum plates ............. 41 Figure 4.2. Relation between optimum-to-minimum ratio and

Fenske separation factor of aavg values ........... 41 Figure 4.3. Optimum-minimum reflux ratio relationship to the

column's feed, distillate, and bottoms composition .. 42 Figure 4.4. Underwood's (J vs. key ratios in feed ............. 43 Figure 4.5. Underwood's (J vs. (a - (J)/a for a in range of

1.01-1.11 .................................. 44 Figure 4.6. Underwood's (J vs. (a - (J)/a for a in range of

1.05-3.00 .................................. 45 Figure 4.7. Underwood's (J vs. (a - (J)/a for heavy key and

heavier components .......................... 46

xi

XII FIGURES

Figure 4.8. Effect of thermal condition of feed on feed tray location ................................... 47

Figure 4.9. Capacity parameter for column diameter .......... 50 Figure 4.10. Tray overall efficiency ........................ 51 Figure 4.11. Generalized pressure drop correlation in packed

towers .................................... 52 Figure 6.1. Correction for pressure drop due to viscosity and

density .................................... 74 Figure 6.2. Pressure drop and flow velocity of water in

plastic-lined pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 Figure 6.3. Viscosity vs. minimum flow to produce turbulent

flow ...................................... 75 Figure 604. Pressure drop for gas flow ..................... 78 Figure 6.5. Pressure drop for gas flow ..................... 79 Figure 6.6. Steam flow chart ............................ 80 Figure 6.7. Fanning friction factor for pipe flow ............. 82 Figure 6.8. Sizing chart for pipe handling liquids in vertical

down flow .................................. 83 Figure 6.9. Basis for Lapp1e charts ........................ 86 Figure 6.10. Lapple charts for compressible flow .............. 87 Figure 6.11. Flow curves for Parshall flumes ................. 88 Figure 6.12. Composite sketch of small Parshall flume . . . . . . . . . . 89 Figure 6.13. Composite sketch of large Parshall flume .......... 90 Figure 6.14. Curves showing relation between 1>1> 1>g, Rio and Rg

for all flow mechanisms ....................... 93 Figure 6.15. Flow coefficient for square-edged orifices ......... 96 Figure 6.16. Net expansion factor Y for compressible flow

through nozzles and orifices .................... 97 Figure 7.1. Particle size classification ...................... 106 Figure 7.2. Particle classification and useful collection equipment

vs. particle size .............................. 107 Figure 7.3. Efficiency curves for various types of dust-collecting

equipment ................................. 108 Figure 704. Cyclone sizing ......... . . . . . . . . . . . . . . . . . . . .. 109 Figure 8.1. Flow of heat through tube walls .. . . . . . . . . . . . . . .. 112 Figure 8.2. Effect of velocity on heat transfer rates ........... 113 Figure 8.3. Heat supplied by 150 psig steam tracer ........... 122 Figure 804. Heat supplied by Dowtherm SR-l tracer .......... 125 Figure 8.5. Tube side heat transfer ........................ 131 Figure 8.6. Shell side heat transfer curve for segmental baffles ... 137 Figure 8.7. Film coefficients for water in tubes .............. 138

Figure 8.8. Figure 8.9. Figure 8.1 O.

Figure 8.11. Figure 8.12. Figure 8.13.

Figure 8.14. Figure 8.15. Figure 8.16. Figure 8.17. Figure 8.18. Figure 8.19. Figure 8.20. Figure 8.21. Figure 8,.22.

Figure 8.23.

Figure 8.24. Figure 9.1. Figure 11.1. Figure 11.2. Figure 11.3. Figure 11.4. Figure 11.5. Figure 11.6. Figure 13.1. Figure 13.2. Figure 13.3.

FIGURES xiii

Tube side friction factors ..................... . Tube side and return pressure drop per tube pass ... . Shell side friction factors for low-finned and plain tubes .................................... . LMTD correction factor F, 1-2 exchangers ....... . LMTD correction factor F, 2-4 exchangers ....... . Natural circulation boiling and sensible film coefficients ................................ . Vertical thermosiphon reboiler connected to tower .. Condenser performance chart .................. . Condensing film coefficients Condensation in vertical tubes ................. . Condenser for material low in light ends ......... . Condensation curve for Figure 8.18 ............. . Condenser for material with broad condensing curve . Condensation curve for Figure 8.20 ............. . Service coefficient vs. outlet viscosity for natural gas and refinery liquid streams .................... . Required surface area for air-cooled heat exchangers as a function of the number of rows, overall U, approach, and cooling range ................... . Curve to find tt2 /MMBtu/hr for example problem .. . Cyclone design and flow patterns ............... . Viscosities of liquids ......................... . Viscosities of gases .......................... . Refrigerant properties ....................... . Specific heats of liquids ...................... . Specific heats of gases at l-atm pressure .......... . Latent heats of vaporization ................... . Pump calculation sheet ....................... . Viscosity correction chart (10-100 gpm) ......... . Viscosity correction chart (100-10,000 gpm) ..... .

139 140

141 142 143

147 148 155 156 156 157 157 157 158

159

161 169 182 213 215 222 226 227 228 236 238 239

Figure 14.1. Conventional relief valve ...................... 244 Figure 14.2. Balanced bellows relief valve ................... 245 Figure 14.3. Comparison of a balanced bellows valve and a

conventional valve ........................... 246 Figure 14.4. Cvs. specific heat ratio k ...................... 247 Figure 14.5. Variable or constant backpressure sizing factor Ky;

10% overpressure ............................ 249 Figure 14.6. Variable or constant backpressure sizing factor Ky;

20% overpressure ............................ 250

xiv FIGURES

Figure 14.7. Figure 15.1. Figure 15.2.

Figure 15.3.

Figure 15.4.

Figure 15.5. Figure 15.6. Figure 18.1. Figure 18.2. Figure 18.3. Figure 18.4.

Figure 19.1.

Figure 19.2.

¢ vs. effective area factor Ka Typical steam ejector ........................ . Capacity correction for molecular weight of entrained gas or vapor ............................... . Capacity correction for temperature of entrained air or steam .......................... , ....... . Effect of using incorrect steam pressure on steam ejectors ................................... . Estimating steam requirements for ejectors ....... . Pressure control of ejectors ................... . Recommended disengaging height .............. . Drum size vs. holding time .................... . Segmental area available for liquid holding time ..... . General arrangement of mesh pad in horizontal vapor-liquid separator ............................ . Guide to ASME Boiler and Pressure Vessel Code, Section VIII, Division I ...................... . ASME Code pressure vessel shell thickness chart ... .

252 257

259

260

262 263 265 278 279 280

281

284 286

Tables

Table Table Table Table Table

Table Table Table

1.1. Power factors for agitators in turbulent flow ...... . 1.2. Static Mixer unit specification table ............ . 1.3. Estimating the number of mixer elements ........ . 1.4. Viscosity correction factor K' ................. . 4.1. Relative performance ratings of contacting devices

for distillation columns ...................... . 4.2. Packing factors for tower packing .............. . 6.1. Suggested fluid velocities in pipe and tubing ...... . 6.2. Resistance of flanged elbows, tees, and bends in

equivalent pipe length ....................... . Table 6.3. Resistance of screwed elbows, tees, and bends in

12 14 22 23

49 54 66

67

equivalent pipe length ........................ 67 Table 6.4. Resistance of valves in equivalent pipe length ...... 68 Table 6.5. Resistance of eccentric and concentric reducers and

sudden line size changes in equivalent pipe length ... 69 Table 6.6. Resistance of horizontal and vertical inlets and outlets

in equivalent pipe length ...................... 70 Table 6.7 A. Cv factors for Tufline valves ................... 70 Table 6.7B. Plug positions for 3-way Tufline valves ........... 71 Table 6.7C. Sizing formulas for Tufline valves ............... 71 Table 6.8. Flow of water through Schedule 40 steel pipe ...... 72 Table 6.9. Flow of air through Schedule 40 steel pipe ........ 76 Table 6.10. Discharge from triangular notch weirs with end

contractions .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 Table 6.11. Discharge from rectangular weirs with end

contractions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 Table 6.12. Dimensions and capacities of small Parshall measuring

flumes .................................... 91 Table 6.13. Dimensions and capacities of large Parshall measuring

flumes .................................... 91 Table 6.14. Flow mechanisms for two-phase flow ............ 93 Table 6.15. Values of Martinelli functions with independent

variable X ................................. 94 Table 6.16. Discharge of air through an orifice ...... . . . . . . . . . 98

xv

XVI TABLES

Table 6.17. Locations of orifices and nozzles relative to pipe fittings .................................... 99

Table 8.1. Inside and outside film coefficient, hi and ho .. . . . .. 114 Table 8.2. Fouling resistance, Fo and Fi ................... 115 Table 8.3. Overall coefficients in typical petrochemical

applications ................................ 118 Table 8.4. Thermal resistance of pipes and tubing ........... 120 Table 8.5. Thermal resistance of glass-lined pipe ............ 120 Table Table

8.6. Overall coefficients for platecoils . . . . . . . . . . . . . . .. 126 8.7. Heat loss from storage tanks and product correction

factors .................................... 126 Table 8.8. Thermal conductivities of some insulating materials 127 Table 8.9. Heat exchanger tube sheet layout count. . . . . . . . . .. 134 Table 8.10. Jacketed glass-lined steel vessel heat transfer ....... 144 Table 8.11. Typical glassed steel reactor dimensions .......... 145 Table 8.12. Typical service coefficients .................... 160 Table 8.13. TheB constant ............................. 160 Table 8.14. Layoutinformation for air-cooled exchangers ... . .. 167 Table 8.15. Face velocities .............................. 168 Table 10.1. Chemical composition of selected metals .......... 185 Table 10.2. Applications of various metals in the chemical

industry .. ,................................ 186 Table 11.1. Thermal conductivities of some building and

insulating materials .......................... 189 Table 11.2. Thermal conductivities, specific heats, and specific

gravities of metals and alloys ................... 193 Table 11.3. Thermal conductivities of liquids ................ 194 Table 11.4. Thermal conductivities of gases and vapors ........ 196 Table 11.5. Cp ICv ratios of specific heats of gases at l-atm

pressure ................................... 198 Table 11.6. Specific heats of organic liquids .. . . . . . . . . . . . . . .. 200 Table 11.7. Specific heats of miscellaneous materials .......... 207 Table 11.8. Specific gravities and molecular weights of liquids ... 209 Table 11.9. Heats of vaporization of organic compounds ....... 210 Table 11.10. Viscosities of liquids ......................... 212 Table 11.11. Viscosities of gases . . . . . . . . . . . . . . . . . . . . . . . . . .. 214 Table 11.12. Coefficients of linear expansion -approximate values 216 Table 11.13. Thermodypamic properties of saturated steam ..... 218 Table 11.14. Physical properties of Freon products ............ 220 Table 11.15. Molecular diffusivities ........................ 224

TABLES xvii

Table 12.1. Dimensions and properties of steel pipe ........... ,231 Table 12.2. Dimensional data, plastic-lined pipe .............. 233 Table 14.1. Kb factor for conventional valves in gas or vapor

service .................................... 246 Table 14.2. Orifice sizes for relief valves . . . . . . . . . . . . . . . . . . .. 247 Table 14.3. Ksh superheat correction factors ................ 251 Table 15.1. Air released from water under vacuum ........... 261 Table 15.2. Pressure range for ejectors ..................... 261 Table 15.3. Estimated air leakage into equipment in vacuum

service .................................... 264 Table 16.1. Volume of cylinders, 15-148 in. diameter ......... 269 Table 16.2. Volume of cylinders, 10-98 ft diameter .......... 270 Table 16.3. Approximate volume of heads .................. 271 Table 16.4. Volume of partially filled horizontal cylinders ..... 272 Table 16.5. Volume of partially filled heads on horizontal tanks 273 Table 17.1. Dimensions and properties of steel tubing. . .. . . ... 275 Table 18.1. Values for R dv ••.•.••••.•••••••••••••••••••• 277 Table 19.1. General notes, ASME code .................... 285 Table 19.2. 150-lb flange pressure-temperature ratings ........ 287 Table 19.3. 300-lb flange pressure-temperature ratings ........ 288