Rules of thumb for chemical engineers: a manual of quick, accurate solutions to everyday process engineering problems

442 Pages·2002·25.98 MB·English

by  Carl R. Branan

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
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To my five grandchildren:
Katherine, Alex, Richard, Matthew and Joseph
Gulf Professional Publishing is an imprint of Elsevier.
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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
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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