Rules of Thumb for Chemical Engineers: Amanual of Quick, Accurate Solutions to Everyday Process Engineering Problems PDF
Preview Rules of Thumb for Chemical Engineers: Amanual of Quick, Accurate Solutions to Everyday Process Engineering Problems
Rules of Thumb for Chemical Engineers RULES OF THUMB FOR CHEMICAL ENGINEERS A manual of quick, accurate solutions to everyday process engineering problems Fourth Edition Carl R. Branan, Editor AMSTERDAM • BOSTON • HEIDELBERG • LONDON NEWYORK • OXFORD • PARIS • SAN DIEGO SAN FRANCISCO • SINGAPORE • SYDNEY• TOKYO Gulf Professional Publishing is an imprint of Elsevier Gulf Professional Publishing is an imprint of Elsevier 30 Corporate Drive, Suite 400, Burlington, MA01803, USA Linacre House, Jordan Hill, Oxford OX2 8DP, UK Copyright ©2005, Elsevier Inc. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Permissions may be sought directly from Elsevier’s Science & Technology Rights Department in Oxford, UK: phone: (+44) 1865 843830, fax: (+44) 1865 853333, e-mail: [email protected]. You may also complete your request on-line via the Elsevier homepage (http://elsevier.com), by selecting “Customer Support” and then “Obtaining Permissions.” Recognizing the importance of preserving what has been written, Elsevier prints its books on acid-free paper whenever possible. Library of Congress Cataloging-in-Publication Data APPLICATION SUBMITTED British Library Cataloguing-in-Publication Data Acatalogue record for this book is available from the British Library. ISBN: 0-7506-7856-9 For information on all Gulf Professional Publishing publications visit our Web site at www.books.elsevier.com 05 06 07 08 09 10 10 9 8 7 6 5 4 3 2 1 Printed in the United States of America Working together to grow libraries in developing countries www.elsevier.com | www.bookaid.org | www.sabre.org To my wife of many manuscripts Contents S E C T I O N O N E 3: Fractionators, 59 Equipment Design 1 Introduction............................................................60 Relative volatility...................................................60 1: Fluid Flow, 2 Minimum reflux......................................................61 Minimum stages.....................................................62 Velocity head............................................................3 Actual reflux and actual theoretical stages............62 Full plant piping.......................................................4 Reflux to feed ratio................................................63 Partially full horizontal pipes...................................5 Actual trays............................................................64 Equivalent length......................................................6 Graphical methods..................................................64 Recommended velocities..........................................7 Tray efficiency........................................................67 Two-phase flow........................................................9 Diameter of bubble cap trays.................................71 Compressible flow—short (plant) lines.................12 Diameter of sieve/valve trays (F factor)................72 Compressible flow—long pipelines.......................18 Diameter of sieve/valve trays (Smith)...................73 Sonic velocity.........................................................21 Diameter of sieve/valve trays (Lieberman)...........75 Metering.................................................................21 Diameter of ballast trays........................................75 Control valves........................................................22 Diameter of fractionators, general.........................77 Safety relief valves.................................................25 Control schemes.....................................................77 Optimization techniques.........................................81 Reboilers.................................................................84 Packed columns......................................................88 2: Heat Exchangers, 29 4: Absorbers, 109 TEMA.....................................................................30 Selection guides......................................................34 Introduction..........................................................110 Pressure drop shell and tube..................................37 Hydrocarbon absorber design...............................110 Temperature difference...........................................39 Hydrocarbon absorbers, optimization..................112 Shell diameter.........................................................40 Inorganic type.......................................................113 Shellside velocity maximum..................................40 Nozzle velocity maximum.....................................41 Heat transfer coefficients........................................41 5: Pumps, 116 Fouling resistances.................................................48 Metal resistances....................................................50 Affinity laws.........................................................117 Vacuum condensers................................................52 Horsepower...........................................................117 Air-cooled heat exchangers: forced vs Efficiency..............................................................117 induced draft.......................................................52 Minimum flow......................................................117 Air-cooled heat exchangers: pressure drop General suction system.........................................118 air side................................................................53 Suction system NPSH available...........................119 Air-cooled heat exchangers: rough rating..............54 Suction system NPSH for studies........................120 Air-cooled heat exchangers: temperature Suction system NPSH with dissolved gas...........121 control.................................................................56 Larger impeller.....................................................121 Miscellaneous rules of thumb................................58 Construction materials..........................................121 vii viii Contents 6: Compressors, 124 Deaerator venting.................................................159 Water alkalinity....................................................160 Ranges of application...........................................125 Blowdown control................................................160 Generalized Z.......................................................125 Impurities in water...............................................160 Generalized K.......................................................126 Conductivity versus dissolved solids...................162 Horsepower calculation........................................127 Silica in steam......................................................163 Efficiency..............................................................131 Caustic embrittlement..........................................163 Temperature rise...................................................133 Waste heat.............................................................165 Surge controls.......................................................133 10: Cooling Towers, 168 7: Drivers, 134 System balances...................................................169 Temperature data..................................................169 Motors: efficiency.................................................135 Performance..........................................................171 Motors: starter sizes.............................................136 Performance estimate: a case history...................173 Motors: service factor..........................................136 Transfer units........................................................173 Motors: useful equations......................................137 Motors: relative costs...........................................137 Motors: overloading.............................................138 S E C T I O N T W O Steam turbines: steam rate...................................138 Process Design 175 Steam turbines: efficiency....................................138 Gas turbines: fuel rates.........................................139 Gas engines: fuel rates.........................................141 11: Refrigeration, 176 Gas expanders: available energy..........................141 Types of systems..................................................177 Estimating horsepower per ton............................177 8: Separators/Accumulators, 142 Horsepower and condenser duty for specific refrigerants........................................................178 Liquid residence time...........................................143 Refrigerant replacements......................................196 Vapor residence time............................................144 Ethylene/propylene cascaded system...................197 Vapor/liquid calculation method..........................145 Steam jet type utilities requirements....................197 Estimating equilibria............................................148 Ammonia absorption type utilities Liquid/liquid calculation method.........................150 requirements.....................................................200 Pressure drop........................................................150 Vessel thickness....................................................151 12: Gasification (by Chris Higman), 201 Gas scrubbers.......................................................151 Reflux drums........................................................151 What Is Gasification?...........................................202 General vessel design tips....................................152 Gasification Theory..............................................202 Feedstocks for Gasification..................................204 9: Boilers, 153 Features of Gasification Systems.........................205 Commercial Gasification Systems.......................207 Trace Components in Gasifier Syngas.................210 Power plants.........................................................154 Controls................................................................154 Thermal efficiency................................................155 13: Gas Treating (updated by Chris Higman), 213 Stack gas enthalpy................................................156 Stack gas quantity................................................157 Introduction..........................................................214 Steam drum stability............................................158 Gas Treating Processes.........................................214 Contents ix Chemical Solvent Processes.................................215 Capital investments..............................................258 Physical Solvent Processes..................................218 Operating costs.....................................................265 Physical/Chemical Solvent Processes..................218 Economics............................................................268 Biological Processes.............................................219 Financing..............................................................272 Solid Bed Scavengers...........................................219 Membranes...........................................................220 18: Reliability, 274 14: Vacuum Systems, 221 Vacuum jets..........................................................222 19: Metallurgy, 277 Typical jet systems...............................................223 Steam supply........................................................224 Embrittlement.......................................................278 Measuring air leakage..........................................225 Stress-corrosion cracking.....................................284 Time to evacuate..................................................225 Hydrogen attack...................................................285 Design recommendations.....................................226 Pitting corrosion...................................................287 Ejector specification sheet....................................227 Creep and creep-rupture life................................288 Metal dusting........................................................290 15: Pneumatic Conveying, 229 Naphthenic acid corrosion...................................292 Fuel ash corrosion................................................293 Types of systems..................................................230 Thermal fatigue....................................................295 Differential pressures...........................................231 Abrasive wear.......................................................297 Equipment sizing..................................................231 Pipeline toughness................................................298 Common corrosion mistakes................................299 16: Blending, 233 20: Safety, 300 Single-stage mixers..............................................234 Multistage mixers.................................................234 Gas/liquid contacting............................................235 Estimating LELand flash.....................................301 Liquid/liquid mixing............................................235 Tank blanketing....................................................301 Liquid/solid mixing..............................................235 Equipment purging...............................................303 Mixer applications................................................236 Static charge from fluid flow...............................304 Shrouded blending nozzle....................................237 Mixture flammability............................................307 Vapor formation rate for tank filling....................237 Relief manifolds...................................................310 Natural ventilation................................................316 21: Controls, 317 S E C T I O N T H R E E Plant Design 239 Introduction..........................................................318 Extra capacity for process control.......................318 17: Process Evaluation, 240 Controller limitations...........................................319 False economy......................................................320 Introduction..........................................................241 Definitions of control modes................................320 Study definition....................................................241 Control mode comparisons..................................320 Process definition.................................................243 Control mode vs application................................320 Battery limits specifications.................................250 Pneumatic vs electronic controls.........................321 Offsite specifications............................................254 Process chromatographs.......................................322
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