Chemical reactors : from design to operation

677 Pages·2004·33.018 MB·English, French

by  Trambouze, Pierre, Euzen, Jean-Paul

INSTITUT FRANÇAIS DU PÉTROLE PUBLICATIONS
Pierre TRAMBOUZE Jean-Paul EUZEN
Former Director of CEDI (IFP) Chief Engineer at CEDI (IFP)
Professor at the IFP School
CHEMICAL
REACTORS
FROM DESIGN TO OPERATION
Translated by
Robert Bononno
Bowne Global Solutions
2t004
Editions T E C H N IP 27, rue Ginoux, 75737 PARIS Cedex 15, FRANCE
Translation of
Les réacteurs chimiques. De la conception à la mise en œuvre
P. Trambouze, J.-R Euzen
© 2002, Éditions Technip, Paris
All rights reserved.
No part of this publication may be reproduced or transmitted in any form or by any means, electronic or
mechanical, including photocopy, recording, or any information storage and retrieval system, without the
prior written permission of the publisher.
© Editions Technip, Paris, 2004.
Printed in France
ISBN 2-7108-0845-5
Table of Contents
FOREWORD V
CHAPTER 1 · DEFINITIONS AND FUNDAMENTAL CONCEPTS 1
1.1 Definitions of stoichiometric values 1
1.1.1 Stoichiometric relations 1
1.1.2 Extent of reaction, conversion, selectivity, and yield 2
1.1.3 Mass selectivity and yield 5
1.1.4 Concluding remarks 5
1.2 Chemical thermodynamics 5
1.2.1 Energy balance of the chemical transformation 5
1.2.2 Chemical equilibria 7
1.3 Chemical kinetics 9
1.3.1 Definition of rate of reaction 10
1.3.2 Ways of expressing the rate of reaction r, 11
1.3.3 Influence of temperature 12
1.3.4 Formal kinetic expressions involving fractional or high orders 13
1.3.5 Other forms of kinetic expression associated with catalytic processes 13
1.3.6 Heterogeneous catalytic reactions 15
1.3.7 Groups of compounds 16
1.3.8 Kinetics based on elementary steps 23
1.3.9 Conclusion 23
1.4 Reactor types 23
1.4.1 Principal characteristics of a reactor 24
1.4.2 Classification of reactors 29
1.4.3 General expression of mass and enthalpy balances 30
1.4.4 Application of the general balance expressions to the various types of ideal reactor 32
VIII Table of Contents
1.5 Residence time distribution 35
1.5.1 Typical distribution functions of fluid flow 35
1.5.2 Experimental determination of distribution functions 38
1.5.3 Distribution functions for various types of flow 40
1.6 Macromixing and micromixing 42
1.6.1 Earliness of mixing 43
1.6.2 Segregation within a fluid 44
1.6.3 Micromixing 46
1.6.4 Use of computational fluid dynamics methods 49
References 49
Nomenclature 51
CHAPTER2 · SINGLE-PHASE REACTORS 53
2.1 Batch reactors 53
2.1.1 Mass and energy balances 53
2.1.2 General case and practical implications 59
2.1.3 Thermal instability 61
2.1.4 Available technologies 69
2.1.5 Mixing systems 75
2.1.6 Reactors involving gradual injection of part of the reactants
and gradual elimination of a product 84
2.1.7 Conclusion 89
2.2 Continuous tubular reactors 89
2.2.1 Mass and energy balances 90
2.2.2 Solutions for a few simple cases 92
2.2.3 Influence of backmixing 94
2.2.4 Available technologies 99
2.2.5 Concluding remarks 104
2.3 Continuous stirred tank reactors (CSTR) 104
2.3.1 Mass and energy balances 105
2.3.2 Solutions for some simple cases 107
2.3.3 Autothermal operation 110
2.3.4 The multistage reactor 115
2.3.5 Available technologies 116
2.3.6 Conclusion 123
2.4 Comparison of the different reactor types 123
2.4.1 Operating conditions and production capacity 123
2.4.2 Conversion 127
2.4.3 Selectivity 136
2.4.4 Concluding remarks 142
References 143
Nomenclature 144
Table of Contents IX
CHAPTER 3 · GENERAL CHARACTERISTICS OF REACTORS WITH TWO FLUID PHASES 145
3.1 Review of two-film theory 145
3.2 Mass transfer accompanied by chemical reaction 148
3.2.1 Irreversible and isothermal reaction in a single phase
and transfer toward the reaction phase 149
3.2.2 Calculating the local flux of a compound transferred from phase I to phase II.... 161
3.2.3 Efficiency in a reaction system with two fluid phases (first-order reaction) 161
3.2.4 Extending the study of transfer phenomena with chemical reaction
to systems with more complex kinetics 164
3.2.5 Comparison of various theories of mass transfer
accompanied by chemical reaction 166
3.3 Influence of mass transfer on chemical transformation 168
3.3.1 Apparent reaction order 168
3.3.2 Apparent activation energy 172
3.3.3 Influence of mass transfer on selectivity 173
3.4 Designing a reactor with two fluid phases 184
3.4.1 Batch reactor with two fluid phases 184
3.4.2 Semi-Continuous gas-liquid reactor 188
3.4.3 Tubular reactor with two fluid phases 192
3.4.4 Continuous stirred tank reactor with two fluid phases 196
3.4.5 Conclusion 197
References 199
Nomenclature 200
CHAPTER 4 · EXPERIMENTAL DATA AND CORRELATIONS FOR GAS-LIQUID REACTORS 201
4.1 Introduction and preliminary definitions 201
4.1.1 Specific interfacial area 203
4.1.2 Holdup 203
4.1.3 Current values of design parameters 203
4.2 Bubble columns 205
4.2.1 General characteristics 205
4.2.2 Hydrodynamics 207
4.2.3 Mass transfer 209
4.2.4 Heat transfer 226
4.2.5 General design considerations 226
4.2.6 Alternative designs 228
4.2.7 Concluding remarks 229
4.3 Gaslifts 229
4.3.1 General characteristics 229
4.3.2 Hydrodynamics 229
X Table of Contents
4.3.3 Mass transfer 232
4.3.4 Heat transfer at the wall 232
4.3.5 General design considerations 232
4.3.6 Concluding remarks 233
4.4 Plate columns 233
4.4.1 General features 233
4.4.2 Hydrodynamics 234
4.4.3 Mass transfer 236
4.4.4 Construction details 238
4.4.5 Submerged plate reactors 240
4.4.6 Concluding remarks 240
4.5 Packed columns 241
4.5.1 General characteristics 241
4.5.2 Hydrodynamics 245
4.5.3 Mass transfer 249
4.5.4 Unconventional packed columns 251
4.5.5 Selection criteria and construction details 253
4.5.6 Comparison of plate columns and packed columns 255
4.5.7 Concluding remarks 256
4.6 Fallins film reactors 257
4.6.1 General characteristics 258
4.6.2 Hydrodynamics 259
4.6.3 Mass transfer 261
4.6.4 Heat transfer 262
4.6.5 Current uses 264
4.6.6 Practical applications 267
4.6.7 Technology 268
4.6.8 Concluding remarks 268
4.7 Mechanically agitated devices 269
4.7.1 General characteristics 269
4.7.2 Hydrodynamics 269
4.7.3 Mass transfer 277
4.7.4 Heat transfer 278
4.7.5 Construction details 278
4.7.6 Concluding remarks 279
4.8 Ejectors 279
4.8.1 Bubble generation 280
4.8.2 Droplet generation 283
4.9 Inline mixers 288
4.9.1 Empty pipes 288
4.9.2 Static mixers 289
Table of Contents XI
4.10 Concluding remarks 290
References 292
Nomenclature 297
CHAPTER 5 · EXPERIMENTAL DATA AND CORREUTIONS FOR LIQUID-LIQUID REACTORS 299
5.1 Introduction 299
5.1.1 Hydrodynamic behavior 302
5.1.2 Mass transfer 305
5.1.3 Scale-up 307
5.2 Spray columns 308
5.2.1 Hydrodynamics 309
5.2.2 Mass transfer 311
5.2.3 Technology 312
5.2.4 Concluding remarks 313
5.3 Perforated plate columns 313
5.3.1 Hydrodynamics 313
5.3.2 Mass transfer 317
5.3.3 Technology 317
5.3.4 Concluding remarks 319
5.4 Packed columns 319
5.4.1 Hydrodynamics 320
5.4.2 Mass transfer 322
5.4.3 Technology 322
5.4.4 Pulsed packed columns 323
5.4.5 Concluding remarks 323
5.5 Static mixers 323
5.5.1 Hydrodynamics 323
5.5.2 Mass transfer 325
5.5.3 Technology 326
5.5.4 Concluding remarks 326
5.6 Columns with rotary agitators 326
5.6.1 Hydrodynamics 329
5.6.2 Mass transfer 334
5.6.3 Technology 335
5.6.4 Concluding remarks 336
5.7 Mixer-settlers 336
5.7.1 Hydrodynamics 337
5.7.2 Mass transfer 338
5.7.3 Consumed power 339
XII Table of Contents
5.7.4 Technology 339
5.7.5 Concluding remarks 341
5.8 Other types of equipment 341
5.8.1 Centrifugal extractors 341
5.8.2 Microreactors 342
5.9 Concluding remarks 342
References 344
Nomenclature 346
CHAPTER 6 · GENERAL CHARACTERISTICS OF HETEROGENEOUS CATALYTIC REACTORS 347
6.1 Introduction 347
6.2 The catalyst 347
6.2.1 The solid 348
6.2.2 The grain 348
6.2.3 Granular mass 353
6.2.4 Monolithic catalysts 355
6.3 Internal diffusion 358
6.3.1 Plane surface 359
6.3.2 Homogeneous spherical particle 360
6.3.3 Spherical particle with an active zone on the periphery 363
6.3.4 Optimization of catalyst geometry 365
6.4 Extending the concepts of the Thiele modulus and effectiveness 367
6.4.1 Non-spherical geometric shapes 368
6.4.2 Other than first-order reactions 368
6.4.3 Reversible reactions 370
6.4.4 Non-isochorous reactions 371
6.4.5 Non-isothermal reactions 372
6.5 Influence of internal diffusion on the selectivity of catalytic chemical reactions 375
6.5.1 Independent parallel first-order reactions 375
6.5.2 First-order twin reactions 376
6.5.3 Consecutive reactions 377
6.6 Estimating the coefficient of diffusion £) 382
e
6.7 Influence of external mass transfer: the concept of global effectiveness 384
6.7.1 Global transfer coefficient 384
6.7.2 Heat transfer on the outer surface of the grain 386
6.7.3 The concept of global grain effectiveness 386
6.7.4 Temperature and concentration gradients 387
6.8 Apparent activation energy of heterogeneous catalytic reactions 388
Table of Contents XIII
6.9 Catalyst deactivation 391
6.9.1 Causes of catalyst deactivation 391
6.9.2 Preventing catalyst deactivation 391
6.9.3 Equations for deactivation kinetics 391
6.9.4 Deactivation accompanied by internal diffusion limitation 392
6.9.5 Concluding remarks 393
6.10 Use of heterogeneous catalysts 394
6.10.1 Conditions for the optimal use of a catalyst 394
6.10.2 The fixed bed 394
6.10.3 The moving bed 396
6.10.4 Reactors with catalyst in suspension 398
6.10.5 Comparison of catalyst technologies 403
References 408
Nomenclature 408
CHAPTER 7 · REACTORS EMPLOYING A FLUID PHASE AND A CATALYTIC SOLID PHASE:
FIXED BED, MOVING BED, FLUIDIZED BED 411
7.1 Introduction 411
7.2 Fixed-bed catalytic reactors 411
7.2.1 Writing the mass balance equations 411
7.2.2 Designing the catalytic bed 414
7.2.3 Discussion concerning the validity of the criteria used 417
7.2.4 Calculation of dynamic pressure drop in a catalytic reactor 418
7.2.5 Influence of external transfer in fixed-bed catalytic reactors 419
7.2.6 Criteria for determining the possible influence of external mass transfer 424
7.2.7 Heat transfer at the reactor wall 425
7.2.8 Thermal stability of fixed-bed catalytic reactors 428
7.2.9 Practical considerations 429
7.2.10 Concluding remarks 443
7.3 Moving-bed catalytic reactors 445
7.3.1 Introduction 445
7.3.2 Design of the moving-bed reactor 445
7.3.3 Applications of moving-bed technology 451
7.4 Fluidized-bed reactors with a single fluid phase 454
7.4.1 General remarks 454
7.4.2 The hydrodynamics of fluidized beds 455
7.4.3 Minimum superficial velocity of fluidization (VsF) 457
m
7.4.4 The terminal velocity of a particle 460
7.4.5 Expansion in a fluidized bed 461
XIV Table of Contents
7.4.6 Fluidized-bed reactor models and correlations 463
7.4.7 Mass and heat transfer between a gas and a solid in the dense phase 471
7.4.8 Heat transfer between the wall and the fluidized bed 471
7.4.9 Introduction of reactants and withdrawal of products 472
7.4.10 Industrial applications 474
References 482
Nomenclature 483
CHAPTER 8 · THREE-PHASE REACTORS: GAS, LIQUID, AND CATALYTIC SOLID 485
8.1 Introduction 485
8.1.1 Reaction at the surface of an isolated catalyst particle 486
8.2 Characteristics of three-phase reactors 491
8.2.1 Bubble columns 492
8.2.2 Mechanically agitated reactors 501
8.2.3 Fixed beds with two-phase flow 502
8.2.4 Moving-bed reactors 528
8.2.5 Three-phase fluidized beds or ebullated beds 530
8.3 Current uses and comparison of three-phase reactors 542
References 545
Nomenclature 551
CHAPTER 9 · CASE STUDIES 553
9.1 Batch and semi-continuous homogeneous reactors 553
9.1.1 Fundamental data 553
9.1.2 Batch reactor 554
9.1.3 Semi-Continuous reactor 557
9.1.4 Concluding remarks 564
9.2 Packed column gas-liquid reactor 564
9.2.1 Fundamental data 565
9.2.2 Writing the molar and heat balances 568
9.2.3 Calculating the transfer parameters 571
9.2.4 Integration of the differential balances 572
9.2.5 Column geometrical characteristics 575
9.2.6 Concluding remarks 575
9.3 Fixed-bed catalytic reactor with a single fluid phase 577
9.3.1 Fundamental data 578
9.3.2 Calculating the volume of catalyst 579
9.3.3 Cost optimization 581