PREFACE TO THE SECOND EDITION xv
PREFACE TO THE FIRST EDITION xvii
1 FUNDAMENTALS OF VAPOR–LIQUID–EQUILIBRIUM (VLE) 1
1.1 Vapor Pressure / 1
1.2 Binary VLE Phase Diagrams / 3
1.3 Physical Property Methods / 7
1.4 Relative Volatility / 7
1.5 Bubble Point Calculations / 8
1.6 Ternary Diagrams / 9
1.7 VLE Nonideality / 11
1.8 Residue Curves for Ternary Systems / 15
1.9 Distillation Boundaries / 22
1.10 Conclusions / 25
Reference / 27
2 ANALYSIS OF DISTILLATION COLUMNS 29
2.1 Design Degrees of Freedom / 29
2.2 Binary McCabe–Thiele Method / 30
2.2.1 Operating Lines / 32
2.2.2 q-Line / 33
2.2.3 Stepping Off Trays / 35
2.2.4 Effect of Parameters / 35
2.2.5 Limiting Conditions / 36
2.3 Approximate Multicomponent Methods / 36
2.3.1 Fenske Equation for Minimum Number of Trays / 37
2.3.2 Underwood Equations for Minimum Reflux Ratio / 37
2.4 Conclusions / 38
3 SETTING UP A STEADY-STATE SIMULATION 39
3.1 Configuring a New Simulation / 39
3.2 Specifying Chemical Components and Physical Properties / 46
3.3 Specifying Stream Properties / 51
3.4 Specifying Parameters of Equipment / 52
3.4.1 Column C1 / 52
3.4.2 Valves and Pumps / 55
3.5 Running the Simulation / 57
3.6 Using Design Spec/Vary Function / 58
3.7 Finding the Optimum Feed Tray and Minimum Conditions / 70
3.7.1 Optimum Feed Tray / 70
3.7.2 Minimum Reflux Ratio / 71
3.7.3 Minimum Number of Trays / 71
3.8 Column Sizing / 72
3.8.1 Length / 72
3.8.2 Diameter / 72
3.9 Conceptual Design / 74
3.10 Conclusions / 80
4 DISTILLATION ECONOMIC OPTIMIZATION 81
4.1 Heuristic Optimization / 81
4.1.1 Set Total Trays to Twice Minimum Number of Trays / 81
4.1.2 Set Reflux Ratio to 1.2 Times Minimum Reflux Ratio / 83
4.2 Economic Basis / 83
4.3 Results / 85
4.4 Operating Optimization / 87
4.5 Optimum Pressure for Vacuum Columns / 92
4.6 Conclusions / 94
5 MORE COMPLEX DISTILLATION SYSTEMS 95
5.1 Extractive Distillation / 95
5.1.1 Design / 99
5.1.2 Simulation Issues / 101
5.2 Ethanol Dehydration / 105
5.2.1 VLLE Behavior / 106
5.2.2 Process Flowsheet Simulation / 109
5.2.3 Converging the Flowsheet / 112
5.3 Pressure-Swing Azeotropic Distillation / 115
5.4 Heat-Integrated Columns / 121
5.4.1 Flowsheet / 121
5.4.2 Converging for Neat Operation / 122
5.5 Conclusions / 126
6 STEADY-STATE CALCULATIONS FOR CONTROL STRUCTURE SELECTION 127
6.1 Control Structure Alternatives / 127
6.1.1 Dual-Composition Control / 127
6.1.2 Single-End Control / 128
6.2 Feed Composition Sensitivity Analysis (ZSA) / 128
6.3 Temperature Control Tray Selection / 129
6.3.1 Summary of Methods / 130
6.3.2 Binary Propane/Isobutane System / 131
6.3.3 Ternary BTX System / 135
6.3.4 Ternary Azeotropic System / 139
6.4 Conclusions / 144
Reference / 144
7 CONVERTING FROM STEADY-STATE TO DYNAMIC SIMULATION 145
7.1 Equipment Sizing / 146
7.2 Exporting to Aspen Dynamics / 148
7.3 Opening the Dynamic Simulation in Aspen Dynamics / 150
7.4 Installing Basic Controllers / 152
7.4.1 Reflux / 156
7.4.2 Issues / 157
7.5 Installing Temperature and Composition Controllers / 161
7.5.1 Tray Temperature Control / 162
7.5.2 Composition Control / 170
7.5.3 Composition/Temperature Cascade Control / 170
7.6 Performance Evaluation / 172
7.6.1 Installing a Plot / 172
7.6.2 Importing Dynamic Results into Matlab / 174
7.6.3 Reboiler Heat Input to Feed Ratio / 176
7.6.4 Comparison of Temperature Control with Cascade CC/TC / 181
7.7 Conclusions / 184
8 CONTROL OF MORE COMPLEX COLUMNS 185
8.1 Extractive Distillation Process / 185
8.1.1 Design / 185
8.1.2 Control Structure / 188
8.1.3 Dynamic Performance / 191
8.2 Columns with Partial Condensers / 191
8.2.1 Total Vapor Distillate / 192
8.2.2 Both Vapor and Liquid Distillate Streams / 209
8.3 Control of Heat-Integrated Distillation Columns / 217
8.3.1 Process Studied / 217
8.3.2 Heat Integration Relationships / 218
8.3.3 Control Structure / 222
8.3.4 Dynamic Performance / 223
8.4 Control of Azeotropic Columns/Decanter System / 226
8.4.1 Converting to Dynamics and Closing Recycle Loop / 227
8.4.2 Installing the Control Structure / 228
8.4.3 Performance / 233
8.4.4 Numerical Integration Issues / 237
8.5 Unusual Control Structure / 238
8.5.1 Process Studied / 239
8.5.2 Economic Optimum Steady-State Design / 242
8.5.3 Control Structure Selection / 243
8.5.4 Dynamic Simulation Results / 248
8.5.5 Alternative Control Structures / 248
8.5.6 Conclusions / 254
8.6 Conclusions / 255
References / 255
9 REACTIVE DISTILLATION 257
9.1 Introduction / 257
9.2 Types of Reactive Distillation Systems / 258
9.2.1 Single-Feed Reactions / 259
9.2.2 Irreversible Reaction with Heavy Product / 259
9.2.3 Neat Operation Versus Use of Excess Reactant / 260
9.3 TAME Process Basics / 263
9.3.1 Prereactor / 263
9.3.2 Reactive Column C1 / 263
9.4 TAME Reaction Kinetics and VLE / 266
9.5 Plantwide Control Structure / 270
9.6 Conclusions / 274
References / 274
10 CONTROL OF SIDESTREAM COLUMNS 275
10.1 Liquid Sidestream Column / 276
10.1.1 Steady-State Design / 276
10.1.2 Dynamic Control / 277
10.2 Vapor Sidestream Column / 281
10.2.1 Steady-State Design / 282
10.2.2 Dynamic Control / 282
10.3 Liquid Sidestream Column with Stripper / 286
10.3.1 Steady-State Design / 286
10.3.2 Dynamic Control / 288
10.4 Vapor Sidestream Column with Rectifier / 292
10.4.1 Steady-State Design / 292
10.4.2 Dynamic Control / 293
10.5 Sidestream Purge Column / 300
10.5.1 Steady-State Design / 300
10.5.2 Dynamic Control / 302
10.6 Conclusions / 307
11 CONTROL OF PETROLEUM FRACTIONATORS 309
11.1 Petroleum Fractions / 310
11.2 Characterization Crude Oil / 314
11.3 Steady-State Design of Preflash Column / 321
11.4 Control of Preflash Column / 328
11.5 Steady-State Design of Pipestill / 332
11.5.1 Overview of Steady-State Design / 333
11.5.2 Configuring the Pipestill in Aspen Plus / 335
11.5.3 Effects of Design Parameters / 344
11.6 Control of Pipestill / 346
11.7 Conclusions / 354
References / 354
12 DIVIDED-WALL (PETLYUK) COLUMNS 355
12.1 Introduction / 355
12.2 Steady-State Design / 357
12.2.1 MultiFrac Model / 357
12.2.2 RadFrac Model / 366
12.3 Control of the Divided-Wall Column / 369
12.3.1 Control Structure / 369
12.3.2 Implementation in Aspen Dynamics / 373
12.3.3 Dynamic Results / 375
12.4 Control of the Conventional Column Process / 380
12.4.1 Control Structure / 380
12.4.2 Dynamic Results and Comparisons / 381
12.5 Conclusions and Discussion / 383
References / 384
13 DYNAMIC SAFETY ANALYSIS 385
13.1 Introduction / 385
13.2 Safety Scenarios / 385
13.3 Process Studied / 387
13.4 Basic RadFrac Models / 387
13.4.1 Constant Duty Model / 387
13.4.2 Constant Temperature Model / 388
13.4.3 LMTD Model / 388
13.4.4 Condensing or Evaporating Medium Models / 388
13.4.5 Dynamic Model for Reboiler / 388
13.5 RadFrac Model with Explicit Heat-Exchanger Dynamics / 389
13.5.1 Column / 389
13.5.2 Condenser / 390
13.5.3 Reflux Drum / 391
13.5.4 Liquid Split / 391
13.5.5 Reboiler / 391
13.6 Dynamic Simulations / 392
13.6.1 Base Case Control Structure / 392
13.6.2 Rigorous Case Control Structure / 393
13.7 Comparison of Dynamic Responses / 394
13.7.1 Condenser Cooling Failure / 394
13.7.2 Heat-Input Surge / 395
13.8 Other Issues / 397
13.9 Conclusions / 398
Reference / 398
14 CARBON DIOXIDE CAPTURE 399
14.1 Carbon Dioxide Removal in Low-Pressure Air Combustion Power Plants / 400
14.1.1 Process Design / 400
14.1.2 Simulation Issues / 401
14.1.3 Plantwide Control Structure / 404
14.1.4 Dynamic Performance / 408
14.2 Carbon Dioxide Removal in High-Pressure IGCC Power Plants / 412
14.2.1 Design / 414
14.2.2 Plantwide Control Structure / 414
14.2.3 Dynamic Performance / 418
14.3 Conclusions / 420
References / 421
15 DISTILLATION TURNDOWN 423
15.1 Introduction / 423
15.2 Control Problem / 424
15.2.1 Two-Temperature Control / 425
15.2.2 Valve-Position Control / 426
15.2.3 Recycle Control / 427
15.3 Process Studied / 428
15.4 Dynamic Performance for Ramp Disturbances / 431
15.4.1 Two-Temperature Control / 431
15.4.2 VPC Control / 432
15.4.3 Recycle Control / 433
15.4.4 Comparison / 434
15.5 Dynamic Performance for Step Disturbances / 435
15.5.1 Two-Temperature Control / 435
15.5.2 VPC Control / 436
15.5.3 Recycle Control / 436
15.6 Other Control Structures / 439
15.6.1 No Te