RULES OF THUMB FOR CHEMICAL ENGINEERS - CNTQ PDF
Preview RULES OF THUMB FOR CHEMICAL ENGINEERS - CNTQ
l V 3 N O I L L I ~ H I Rules of Thumb for Chemical Engineers RULES OF THUMB FOR CHEMICAL ENGINEERS A manual of quick, accurate solutions to everyday process engineering problems Third Edition Carl R. Branan, Editor Gulf Professional Publishing an imprint of Elsevier Science Amsterdam London New York Oxford Paris Tokyo Boston San Diego San Francisco Singapore Sydney To my five grandchildren: Katherine, Alex, Richard, Matthew and Joseph Gulf Professional Publishing is an imprint of Elsevier. Copyright by Elsevier (US.4). All rights reserved. Originally published by Gulf Publishing Company, Houston, TX No part of this publication ma!; 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 Osford, UK: phone: (+44) 1865 843830, fax: (+44) 1865 853333, e-mail: permissions~,elsei,ier.co.ukY. ou may also complete your request on-line via the Elsevier Science homepage (http://uww.elsevier.com), by selecting 'Customer Support' and then 'Obtaining Permissions'. ,-- . E' This book is printed on acid-free paper. Library of Congress Cataloging-in-Publication Data Rules of thumb for chemical engineers: a manual of quick, accurate solutions to eievday process engineering problernsiCar1 R. Branan, editor.-3Id ed. p. cm. Includes index. ISBN 0-7506-7567-5 (pbk.: akpaper) 1. Chemical engineering-Handbooks, manuals, etc. I. Branan, Carl. TPl5l.R85 2002 660-dc2 1 2002071157 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British LibrarJ.. The publisher offers special discounts on bulk orders of this book. For information, please contact: Manager of Special Sales Elsevier Science 200 Wheeler Road Burlington, MA 01803 Tel: 781-3 13-4700 Fax: 781-313-4802 For information on all Gulf publications available, contact our World Wide Web homepage at httD:!'i\nr.lv.bh.com:vuIf 10 9 8 7 6 5 4 3 2 Printed in the United States of America. S E C T I O N O N E 3: Fractionators. 49 Equipment Design 1 Introduction ............................................................ 50 Relative volatility ................................................... 50 1: Fluid Flow. 2 Minimum reflux. ..................................................... 51 Minimum stages ..................................................... 52 Velocity head ............................................................ 3 Actual reflux and actual theoretical stages ............5 2 Piping pressure drop .................................................. Reflux to feed ratio ................................................ 53 Equivalent length ...................................................... 4 Actual trays ............................................................ 54 Recommended velocities .......................................... 5 Graphical methods .................................................. 54 .. Two-phase flow ........................................................ 7 Tray efficiency .......................................................... Compressible flow .................................................... 9 Diameter of bubble cap trays ................................. 59 Sonic velocity ......................................................... 12 Diameter of sieve/valve trays (F factorj ................6 0 Metering ................................................................. 12 Diameter of sievehralve trays (Smith) ...................6 1 Control valves ........................................................ 13 Diameter of sievehlve trays (Lieberman) ...........6 3 Safety relief valves ................................................. 16 Diameter of ballast trays ........................................ 63 . Diameter of fractionators general ......................... 65 Control schemes ..................................................... 65 Optimization techniques ......................................... 69 Reboilers ................................................................. 72 Packed columns ...................................................... 76 2: Heat Exchangers. 19 4: Absorbers. 97 TEMA ..................................................................... 20 Selection guides ...................................................... 24 Introduction ............................................................ 98 Pressure drop shell and tube .................................. 27 Hydrocarbon absorber design ................................ 98 Temperature difference ........................................... 29 . Hydrocarbon absorbers optimization ..................1 00 Shell diameter ......................................................... 30 Inorganic type ....................................................... 101 Shellside velocity maximum .................................. 30 Nozzle velocity maximum ..................................... 3 1 Heat transfer coefficients ........................................ 3 1 5: Pumps. 104 Fouling resistances ................................................. 38 Metal resistances .................................................... 40 Affinity laws ......................................................... 105 Vacuuni condensers ................................................ 42 Horsepower ........................................................... 105 Air-cooled heat exchangers: forced vs Efficienc. ............................................................... 105 induced draft ....................................................... 42 Minimum fl0.c. ...................................................... 105 Air-cooled heat exchangers: psessure drop General suction system ........................................ 106 air side ................................................................ 43 Suction system NPSH available .......................... 107 Air-cooled heat exchangers: rough rating ..............4 4 Suction system NPSH for studies ........................ 108 Air-cooled heat exchangers: temperature Suction system NPSH with dissolved gas ...........1 09 control ................................................................. 46 Larger impeller ..................................................... 109 Miscellaneous rules of thumb ................................ 48 Construction materials .......................................... 109 V vi Contents 6: Compressors. 112 Impurities in water ............................................... 145 Conductivity versus dissolved solids ................... 147 Ranges of application ........................................... 113 Silica in steam ...................................................... 148 Generalized Z ....................................................... 113 Caustic embrittlement .......................................... 148 Generalized K ....................................................... 114 Waste heat ............................................................. 150 Horsepower calculation ........................................ 11 5 Efficiencp .............................................................. 119 10: Cooling Towers. 153 Temperature rise ................................................... 121 Surge controls ....................................................... 12 1 System balances ................................................... 154 Temperature data .................................................. 154 7: Drivers. 122 Performance .......................................................... 156 Performance estimate: a cast history ................... 158 Transfer units ........................................................ 158 Motors: efficiency ................................................. 123 Motors: starter sizes ............................................. 124 Motors: service factor .......................................... 124 Motors: useful equations ...................................... 125 S E C T I O N T W O Motors: relative costs ........................................... 125 Motors: overloading ............................................. 126 Process Design 161 Steam turbines: steam rate ................................... 126 Steam turbines: efficiency .................................... 126 11: Refrigeration. 162 Gas turbines: fuel rates ......................................... 127 Gas engines: fuel rates ......................................... 129 Types of systems .................................................. 163 Gas expanders: available energy .......................... 129 Estimating horsepower per ton ............................ 163 Horsepower and condenser duty for specific 8: SeparatorslAccumulators. 13 0 refrigerants ........................................................ 164 Refrigerant replacements ...................................... 182 Liquid residence time ........................................... 131 Ethylene/propylene cascaded system ................... 183 Vapor residence time ............................................ 132 Steam jet type utilities requirements .................... 183 VaporAiquid calculation method .......................... 133 Ammonia absorption type utilities LiquidAiquid calculation method ......................... 135 requirements ..................................................... 186 Pressure drop ........................................................ 135 Vessel thickness .................................................... 136 12: Gas Treating. 187 Gas scrubbers ....................................................... 136 Reflux drums ........................................................ 136 Introduction .......................................................... 188 General vessel design tips .................................... 137 Gas treating processes .......................................... 188 Reaction type gas treating .................................... 190 9: Boilers. 138 Physical solvent gas treating ................................ 191 PhysicaVchemical type ......................................... 191 Carbonate type ...................................................... 192 Power plants ......................................................... 139 Solution batch type ............................................... 192 Controls ................................................................ 139 Bed batch type ...................................................... 193 Thermal efficiency ................................................ 140 Stack gas enthalpy ................................................ 141 Stack gas quantity ................................................ 142 13: ~aCUUms ystems. 194 Steam drum stability ............................................ 143 Deaerator venting ................................................. 144 Vacuum jets .......................................................... 195 Water alkalinity .................................................... 145 Typical jet systems ............................................... 196 Blowdown control ................................................ 145 Steam supply ........................................................ 197 Contents vii Measuring air leakage .......................................... 198 Creep and creep-rupture life ................................ 260 Metal dusting ........................................................ 262 Time to evacuate .................................................. 198 Design recommendations ..................................... 199 Naphthenic acid corrosion ................................... 264 Ejector specification sheet .................................... 200 Fuel ash corrosion ................................................ 265 Thermal fatigue .................................................... 267 Abrasive wear ....................................................... 269 14: Pneumatic Conveying. 202 Pipeline toughness ................................................ 270 Common corrosion mistakes ................................ 271 Types of systems .................................................. 203 Differential pressures ........................................... 204 . . Equipment sizing .................................................. 204 19: Safety. 272 15: Blending. 206 Estimating LEL and flash ..................................... 273 Tank blanketing .................................................... 273 Single-stage mixers .............................................. 207 Equipment purging ............................................... 275 Multistage mixers ................................................. 207 Static charge from fluid flow ............................... 276 Gadliquid contacting ............................................ 208 Mixture flammability ............................................ 279 Liquid/liquid mixing ............................................ 208 Relief manifolds ................................................... 282 Liquidkolid mixing .............................................. 208 Natural ventilation ................................................ 288 Mixer applications ................................................ 209 Shrouded blending nozzle .................................... 210 Vapor formation rate for tank filling .................... 210 20: Controls. 289 Introduction .......................................................... 290 Extra capacity for process control ....................... 290 S E C T I O N T H R E E Controller limitations .......................................... 291 Plant Design 21 1 False economy ...................................................... 292 Definitions of control modes ................................ 292 Control mode comparisons .................................. 292 16: Process Evaluation. 212 Control mode vs application ................................ 292 Pneumatic vs electronic controls ......................... 293 Introduction .......................................................... 2 13 Process chromatographs ....................................... 294 Study definition .................................................... 2 13 Process definition ................................................. 2 15 Battery limits specifications ................................. 222 Offsite specifications ............................................ 226 Capital investments .............................................. 230 S E C T I O N F O U R Operating costs ..................................................... 237 Operations 285 Economics ............................................................ 240 Financing .............................................................. 244 21 : Troubleshooting. 296 67: Reliability. 247 Introduction .......................................................... 297 Fractionation: initial checklists ............................ 297 18: Metallurgy. 249 Fractionation: Troubleshooting checklist .............2 99 Fractionation: operating problems ....................... 301 Embrittlement ........................................................ 250 Fractionation: mechanical problems .................... 307 Stress-corrosion cracking ..................................... 256 Fractionation: Getting ready for Hydrogen attack ................................................... 257 troubleshooting ................................................. 311 Pitting corrosion ................................................... 259 Fractionation: “Normal” parameters .................... 312 viii Contents Fluid flow ............................................................. 313 Autoignition temperature ..................................... 371 Refrigeration ......................................................... 316 Gibbs free energy of formation ............................ 376 Firetube heaters .................................................... 317 New refrigerants ................................................... 386 Safety relief valves ............................................... 318 Gas treating .......................................................... 319 26: Approximate Conversion Factors. 387 Compressors ......................................................... 323 Measurement ........................................................ 325 Approximate conversion factors .......................... 388 22: Startup. 326 Introduction .......................................................... 327 Appendixes 389 Settings for controls ............................................. 327 Probable causes of trouble in controls ................. 328 Appendix 1: Shortcut Equipment Design Checklists ............................................................. 330 Methods.0verview. 390 23: Energy Conservation. 334 Appendix 2: Geographic Information Systems. 392 Target excess oxygen ........................................... 335 Stack heat loss ...................................................... 336 Appendix 3: Internet Ideas. 394 Stack gas dew point ............................................. 336 Equivalent fuel values .......................................... 338 Heat recovery systems ......................................... 339 Appendix 4: Process Safety Management. 397 Process efficiency ................................................. 340 Steam traps ........................................................... 341 Appendix 5: Do-It-Yourself Shortcut Methods. 399 Gas expanders ...................................................... 343 Fractionation ......................................................... 344 Insulating materials .............................................. 344 Appendix 6: Overview for Engineering Students. 406 24: Process Modeling Using Linear Programming. Appendix 7: Modern Management Initiatives. 409 345 Process modeling using linear programming .................................................... 346 Appendix 8: Process Specification Sheets. 410 Vessel data sheet ................................................... 411 25: Properties. 351 Shell and tube exchanger data sheet .................... 412 Double pipe (G-fin) exchanger data sheet ...........4 13 Introduction .......................................................... 352 Air-cooled (fin-fan) exchanger data sheet ...........4 14 Approximate physical properties ......................... 352 Direct fired heater data sheet ............................... 415 Viscosity ............................................................... 353 Centrifugal pump (horizontal or vertical) Relative humidity ................................................. 357 data sheet .......................................................... 416 Surface tension ..................................................... 358 Pump (vertical turbine-can or propellor) Gas diffusion coefficients ..................................... 358 data sheet .......................................................... 417 Water and hydrocar~on.s.. .................................... 360 Tank data sheet ..................................................... 418 Natural gas hydrate temperature .......................... 364 Cooling tower data sheet ...................................... 419 Inorganic gases in petroleum ............................... 366 Foam density ........................................................ 368 EquiITalent diameter .............................................. 369 Index. 423 S E C T I O N O N E Equipment Design
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