Reactive Distillation Design and Control

REACTIVE DISTILLATION DESIGN AND CONTROL......Page 4
CONTENTS......Page 10
PREFACE......Page 20
1 INTRODUCTION......Page 26
1.1 History......Page 27
1.2 Basics of Reactive Distillation......Page 28
1.3 Neat Operation Versus Excess Reactant......Page 32
1.4.1 Temperature Mismatch......Page 33
1.5 Scope......Page 34
1.6.2 Aspen Simulations......Page 35
1.7 Reference Materials......Page 36
PART I STEADY-STATE DESIGN OF IDEAL QUATERNARY SYSTEM......Page 40
2 PARAMETER EFFECTS......Page 42
2.1 Effect of Holdup on Reactive Trays......Page 45
2.2 Effect of Number of Reactive Trays......Page 47
2.3 Effect of Pressure......Page 49
2.4 Effect of Chemical Equilibrium Constant......Page 52
2.5 Effect of Relative Volatilities......Page 54
2.5.2 Temperature-Dependent Relative Volatilities......Page 55
2.6 Effect of Number of Stripping and Rectifying Trays......Page 57
2.7.1 Reactant A Feed Location (N(FA))......Page 58
2.7.2 Reactant B Feed Location (N(FB))......Page 60
2.8 Conclusion......Page 61
3 ECONOMIC COMPARISON OF REACTIVE DISTILLATION WITH A CONVENTIONAL PROCESS......Page 62
3.1.1 Assumptions and Specifications......Page 63
3.1.2 Steady-State Design Procedure......Page 65
3.1.3 Sizing and Economic Equations......Page 67
3.2 Reactive Distillation Design......Page 68
3.2.1 Assumptions and Specifications......Page 69
3.2.2 Steady-State Design Procedure......Page 70
3.3.1 Conventional Process......Page 72
3.3.2 Reactive Distillation Process......Page 79
3.4 Results for Temperature-Dependent Relative Volatilities......Page 86
3.4.1 Relative Volatilities......Page 87
3.4.2 Optimum Steady-State Designs......Page 89
3.4.3 Real Chemical Systems......Page 94
3.5 Conclusion......Page 95
4 NEAT OPERATION VERSUS USING EXCESS REACTANT......Page 96
4.2 Neat Reactive Column......Page 97
4.3 Two-Column System with Excess B......Page 100
4.3.1 20% Excess B Case......Page 101
4.3.2 10% Excess B Case......Page 103
4.4 Two-Column System with 20% Excess of A......Page 106
4.5 Economic Comparison......Page 110
4.6 Conclusion......Page 111
PART II STEADY-STATE DESIGN OF OTHER IDEAL SYSTEMS......Page 112
5 TERNARY REACTIVE DISTILLATION SYSTEMS......Page 114
5.1.2 Chemistry and Phase Equilibrium Parameters......Page 115
5.1.3 Design Parameters and Procedure......Page 117
5.1.7 Number of Stripping Trays......Page 119
5.2.2 Chemistry and Phase Equilibrium Parameters......Page 124
5.2.3 Design Parameters and Procedure......Page 125
5.2.4 Effect of Pressure......Page 127
5.2.5 Control Tray Composition......Page 128
5.2.6 Reactive Tray Holdup......Page 130
5.2.7 Effect of Reflux......Page 132
5.2.9 Feed Composition......Page 134
5.2.11 Number of Rectifying and Stripping Trays......Page 138
5.3 Conclusion......Page 141
6 TERNARY DECOMPOSITION REACTION......Page 144
6.1.2 Chemistry and Phase Equilibrium Parameters......Page 145
6.1.3 Design Parameters and Procedure......Page 146
6.1.4 Holdup on Reactive Trays......Page 148
6.1.5 Number of Reactive Trays......Page 149
6.1.7 Location of Feed Tray......Page 151
6.2.1 Column Configurations......Page 152
6.2.3 Design Parameters and Procedure......Page 153
6.2.4 Reactive Holdup......Page 154
6.2.5 Number of Reactive Trays......Page 156
6.2.6 Number of Rectifying Trays......Page 157
6.3.1 Feasibility Analysis......Page 159
6.3.5 Number of Reactive Trays......Page 164
6.3.6 Number of Rectifying Trays......Page 165
6.4 Conclusion......Page 168
PART III STEADY-STATE DESIGN OF REAL CHEMICAL SYSTEMS......Page 170
7.1.1 Reaction Kinetics......Page 172
7.1.2 Phase Equilibria......Page 174
7.2.1 Type I Flowsheet: MeAc......Page 178
7.2.2 Type II Flowsheet: EtAc and IPAc......Page 181
7.2.3 Type III Flowsheet: BuAc and AmAc......Page 182
7.3.1 Design Procedure......Page 183
7.3.2 Optimized Design......Page 185
7.4.2 Type II: EtAc and IPAc......Page 193
7.4.3 Type III: BuAc and AmAc......Page 196
7.5 Discussion......Page 200
7.6 Conclusion......Page 202
8 DESIGN OF TAME REACTIVE DISTILLATION SYSTEMS......Page 204
8.1.1 Chemical Kinetics......Page 205
8.1.2 Phase Equilibrium Using Aspen Plus......Page 206
8.1.3 Conceptual Design......Page 211
8.2 Component Balances......Page 219
8.3.1 Base Case Design of Reactive Column......Page 220
8.3.2 Effect of Design Parameters on Reactive Column......Page 224
8.4 Pressure-Swing Methanol Separation Section......Page 233
8.5 Extractive Distillation Methanol Separation Section......Page 234
8.6 Economic Comparison......Page 235
8.7 Conclusion......Page 237
9.1 MTBE Process......Page 238
9.1.3 Aspen Plus Simulation Issues......Page 239
9.1.4 Setting up the Aspen Plus Simulation......Page 240
9.1.5 Effect of Design Parameters......Page 244
9.1.6 Chemical Equilibrium Model......Page 250
9.2.1 Kinetic Model......Page 255
9.2.2 Process Studied......Page 256
9.2.3 User Subroutine for ETBE......Page 258
9.2.4 Chemical Equilibrium Model......Page 259
9.2.5 Effects of Design Parameters......Page 261
9.3 Conclusion......Page 262
PART IV CONTROL OF IDEAL SYSTEMS......Page 264
10 CONTROL OF QUATERNARY REACTIVE DISTILLATION COLUMNS......Page 266
10.1 Introduction......Page 267
10.2 Steady-State Design......Page 268
10.3 Control Structures......Page 270
10.4 Selection of Control Tray Location......Page 271
10.5.1 CS7-R Structure......Page 272
10.5.2 CS7-RR Structure......Page 273
10.6.1 Steady-State Design......Page 274
10.6.2 SVD Analysis......Page 275
10.6.3 Dynamic Performance of CS7-RR......Page 278
10.7 Increasing Holdup on Reactive Trays......Page 279
10.8 Rangeability......Page 281
10.9 Conclusion......Page 284
11.1 Control Degrees of Freedom......Page 286
11.2 Single Reactive Column Control Structures......Page 288
11.2.1 Two-Temperature Control Structure......Page 290
11.2.2 Internal Composition Control Structure......Page 297
11.3 Control of Two-Column System......Page 303
11.3.1 Two-Temperature Control......Page 304
11.3.2 Temperature/Composition Cascade Control......Page 310
11.4 Conclusion......Page 317
12.1.1 Column Configuration......Page 318
12.1.2 Control Structure CS1......Page 321
12.1.3 Control Structure CS2......Page 325
12.1.4 Control Structure CS3......Page 328
12.2.2 Control Structure CS1......Page 335
12.2.3 Control Structure CS2......Page 339
12.2.4 Control Structure CS3......Page 345
12.2.5 Conclusion for Ternary A + B C System......Page 347
12.3.1 Column Configuration......Page 349
12.3.2 Control Structure CS1......Page 351
12.3.3 Control Structure CS2......Page 354
12.4.2 Control Structure CS1......Page 359
12.4.3 Control Structure CS2......Page 360
12.5.2 Control Structure CS1......Page 367
12.5.3 Control Structure CS2......Page 369
12.5.4 Control Structure CS3......Page 370
12.5.5 Conclusion for Ternary A B + C System......Page 377
PART V CONTROL OF REAL SYSTEMS......Page 378
13.1.1 Process Studies......Page 380
13.1.2 Quantitative Analysis......Page 381
13.2 Control Structure Design......Page 387
13.2.1 Selection of Temperature Control Trays......Page 388
13.2.2 Control Structure and Controller Design......Page 391
13.2.3 Performance......Page 393
13.2.4 Alternative Temperature Control Structures......Page 401
13.3 Extension to Composition Control......Page 405
13.4 Conclusion......Page 413
14.1 Process Studied......Page 414
14.1.1 Prereactor......Page 415
14.1.3 Extractive Column C2......Page 416
14.2.1 Prereactor......Page 422
14.2.3 Extractive Distillation Column C2......Page 424
14.2.4 Methanol Recovery Column C3......Page 426
14.3 Results......Page 428
14.4 Conclusion......Page 431
15.1.1 Steady State......Page 432
15.1.2 Control Structure with C4 Feedflow Controlled......Page 433
15.1.3 Control Structure with Methanol Feedflow Controlled......Page 441
15.2 ETBE Control......Page 443
15.2.1 Control Structure with Flow Control of C4 Feed......Page 444
15.2.2 Control Structure with Flow Control of Ethanol Feed......Page 449
PART VI HYDRID AND NONCONVENTIONAL SYSTEMS......Page 454
16.1 Introduction......Page 456
16.2 Design for Quaternary Ideal System......Page 458
16.2.1 Assumptions and Specifications......Page 459
16.2.2 Reactor and Column Equations......Page 460
16.2.3 Design Optimization Procedure......Page 461
16.2.4 Results and Discussion......Page 462
16.2.5 Reactive Column with Optimum Feed Tray Locations......Page 470
16.3.1 Dynamic Tubular Reactor Model......Page 471
16.3.2 Control Structures......Page 472
16.4.1 Process Description......Page 483
16.4.2 Conceptual Design......Page 484
16.5 Control of Column/Side Reactor Process for Ethyl Acetate System......Page 499
16.5.1 Determining Manipulated Variables......Page 500
16.5.2 Selection of Temperature Control Trays......Page 504
16.5.4 Performance......Page 506
16.6 Conclusion......Page 510
17.1.1 Process......Page 512
17.1.2 Classification......Page 515
17.2 Relaxation and Convergence......Page 517
17.3 Process Configurations......Page 520
17.3.1 Type I: One Group......Page 521
17.3.2 Type II: Two Groups......Page 526
17.3.3 Type III: Alternating......Page 532
17.4.1 Summary......Page 536
17.4.2 Excess Reactant Design......Page 539
17.5 Conclusion......Page 543
18.1 Process Characteristics......Page 544
18.1.1 Modeling......Page 546
18.1.3 Base Case......Page 547
18.1.4 Feed Locations Versus Reactants Distribution......Page 548
18.1.5 Optimal Feed Locations......Page 552
18.2.1 Changing Relative Volatilities of Reactants......Page 554
18.2.2 Changing Relative Volatilities of Products......Page 555
18.2.3 Summary......Page 557
18.3.1 Reducing Activation Energies......Page 558
18.3.2 Effects of Preexponential Factor......Page 561
18.4.1 Optimal Feed Location for Production Rate Variation......Page 563
18.4.2 Control Structure......Page 564
18.4.3 Closed-Loop Performance......Page 566
18.5 Conclusion......Page 569
APPENDIX CATALOG OF TYPES OF REAL REACTIVE DISTILLATION SYSTEMS......Page 570
REFERENCES......Page 588
INDEX......Page 598