# Separation Process Engineering, 4th edition

Published by Pearson (August 15, 2016) Â© 2017

**Phillip C. Wankat**

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** Separation Process Engineering, Fourth Edition,**Â offers student- and faculty-friendly coverage of all currently important methods for chemical engineering separation. It teaches via detailed examples, using real data to solve real engineering problems, all organized in a common format to streamline learning. This edition also provides new homework problems, spreadsheet-based exercises, and well-tested, laboratory-style computer simulations that make it far easier to teach an up-to-date course.

- Reflects an up-to-date understanding of how modern students learn: designed, organized, and written to be exceptionally clear and easy to use
- Presents detailed examples in a clear, standard format, using real data to solve actual engineering problems
- Presents extensive coverage and examples of flash distillation, extractive and azeotropic distillation, batch distillation, absorption, stripping, extraction, crystallization, membrane separations, adsorption, ion exchange and chromatography
- Thoroughly covers mass transfer fundamentals and applications

This edition contains:

- Expanded coverage of mass transfer fundamentals and their application in separation processes
- 300+ new problems covering a wider range of challenges
- Updates to refresh all chapters
- An entirely new chapter on crystallization
- Detailed computer simulation exercises for process simulators (including Aspen Plus and Aspen Chromatography), presented in chapter appendices to avoid confusion
- New exercises for Excel spreadsheets

Preface xix

Acknowledgments xxi

About the Author xxiii

Nomenclature xxv

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**Chapter 1: Introduction to Separation Process Engineering 1**

1.0. Summaryâ€”Objectives 1

1.1. Importance of Separations 1

1.2. Concept of Equilibrium 3

1.3. Mass Transfer Concepts 4

1.4. Problem-Solving Methods 5

1.5. Units 7

1.6. Computers and Computer Simulations 8

1.7. Prerequisite Material 8

1.8. Other Resources on Separation Process Engineering 9

References 11

Homework 12

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**Chapter 2: Flash Distillation 15**

2.0. Summaryâ€”Objectives 15

2.1. Basic Method of Flash Distillation 15

2.2. Form and Sources of Equilibrium Data 17

2.3. Graphical Representation of Binary VLE 20

2.4. Binary Flash Distillation 25

2.5. Multicomponent VLE 32

2.6. Multicomponent Flash Distillation 36

2.7. Simultaneous Multicomponent Convergence 42

2.8. Three-Phase Flash Calculations 47

2.9. Size Calculation 48

2.10. Using Existing Flash Drums 53

References 54

Homework 55

Appendix A. Computer Simulation of Flash Distillation 67

Appendix B. Spreadsheets for Flash Distillation 77

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**Chapter 3: Introduction to Column Distillation 81**

3.0. Summaryâ€”Objectives 81

3.1. Developing a Distillation Cascade 82

3.2. Distillation Equipment 88

3.3. Specifications 90

3.4. External Column Balances 94

References 98

Homework 98

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**Chapter 4: Binary Column Distillation: Internal Stage-by-Stage Balances 105**

4.0. Summaryâ€”Objectives 105

4.1. Internal Balances 106

4.2. Binary Stage-by-Stage Solution Methods 110

4.3. Introduction to the McCabe-Thiele Method 116

4.4. Feed Line 120

4.5. Complete McCabe-Thiele Method 128

4.6. Profiles for Binary Distillation 132

4.7. Open Steam Heating 132

4.8. General McCabe-Thiele Analysis Procedure 138

4.9. Other Distillation Column Situations 146

4.10. Limiting Operating Conditions 151

4.11. Efficiencies 154

4.12. Simulation Problems 156

4.13. New Uses for Old Columns 158

4.14. Subcooled Reflux and Superheated Boilup 159

4.15. Comparisons Between Analytical and Graphical Methods 161

References 162

Homework 163

Appendix A. Computer Simulation of Binary Distillation 179

Appendix B. Spreadsheets for Binary Distillation 183

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**Chapter 5: Introduction to Multicomponent Distillation 189**

5.0. Summaryâ€”Objectives 189

5.1. Calculational Difficulties 189

5.2. Profiles for Multicomponent Distillation 194

5.3. Stage-by-Stage Calculations for CMO 199

References 206

Homework 206

Appendix A. Simplified Spreadsheet for Stage-by-Stage Calculations for Ternary Distillation 212

Appendix B. Automated Spreadsheet with VBA for Stage-by-Stage Calculations for Ternary Distillation 215

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**Chapter 6 Exact Calculation Procedures for Multicomponent Distillation 219**

6.0. Summaryâ€”Objectives 219

6.1. Introduction to Matrix Solution for Multicomponent Distillation 219

6.2. Component Mass Balances in Matrix Form 221

6.3. Initial Guesses for Flow Rates and Temperatures 225

6.4. Temperature Convergence 225

6.5. Energy Balances in Matrix Form 229

6.6. Introduction to Naphtali-Sandholm Simultaneous Convergence Method 232

6.7. Discussion 233

References 234

Homework 235

Appendix. Computer Simulations for Multicomponent Column Distillation 241

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**Chapter 7: Approximate Shortcut Methods for Multicomponent Distillation 249**

7.0. Summaryâ€”Objectives 249

7.1. Total Reflux: Fenske Equation 250

7.2. Minimum Reflux: Underwood Equations 254

7.3. Gilliland Correlation for Number of Stages at Finite Reflux Ratios 259

References 263

Homework 263

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**Chapter 8: Introduction to Complex Distillation Methods 271**

8.0. Summaryâ€”Objectives 271

8.1. Breaking Azeotropes with Other Separators 272

8.2. Binary Heterogeneous Azeotropic Distillation Processes 273

8.3. Steam Distillation 282

8.4. Pressure-Swing Distillation Processes 286

8.5. Complex Ternary Distillation Systems 287

8.6. Extractive Distillation 296

8.7. Azeotropic Distillation with Added Solvent 302

8.8. Distillation with Chemical Reaction 306

References 309

Homework 310

Appendix A. Simulation of Complex Distillation Systems 326

Appendix B. Spreadsheet for Residue Curve Generation 336

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**Chapter 9: Batch Distillation 339**

9.0. Summaryâ€”Objectives 339

9.1. Introduction to Batch Distillation 339

9.2. Batch Distillation: Rayleigh Equation 341

9.3. Simple Binary Batch Distillation 344

9.4. Constant-Mole Batch Distillation 349

9.5. Batch Steam Distillation 350

9.6. Multistage Binary Batch Distillation 352

9.7. Multicomponent Simple Batch Distillation 357

9.8. Operating Time 361

References 362

Homework 363

Appendix A. Spreadsheet for Simple Multicomponent Batch Distillation, Constant Relative Volatility 372

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**Chapter 10: Staged and Packed Column Design 375**

10.0. Summaryâ€”Objectives 375

10.1. Staged Column Equipment Description 376

10.2. Tray Efficiencies 385

10.3. Column Diameter Calculations 390

10.4. Balancing Calculated Diameters 396

10.5. Sieve Tray Layout and Tray Hydraulics 398

10.6. Valve Tray Design 404

10.7. Introduction to Packed Column Design 406

10.8. Packings and Packed Column Internals 406

10.9. Height of Packing: HETP Method 409

10.10. Packed Column Flooding and Diameter Calculation 411

10.11. Economic Trade-Offs for Packed Columns 417

10.12. Choice of Column Type 418

References 421

Homework 425

Appendix. Tray and Downcomer Design with Computer Simulator 433

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**Chapter 11: Economics and Energy Conservation in Distillation 437**

11.0. Summaryâ€”Objectives 437

11.1. Equipment Costs 438

11.2. Basic Heat Exchanger Design 443

11.3. Design and Operating Effects on Costs 445

11.4. Changes in Plant Operating Rates 454

11.5. Energy Conservation in Distillation 455

11.6. Synthesis of Column Sequences for Almost Ideal Multicomponent Distillation 460

11.7. Synthesis of Distillation Systems for Nonideal Ternary Systems 466

References 470

Homework 472

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**Chapter 12: Absorption and Stripping 481**

12.0. Summaryâ€”Objectives 482

12.1. Absorption and Stripping Equilibria 483

12.2. McCabe-Thiele Solution for Dilute Absorption 485

12.3. Stripping Analysis for Dilute Systems 489

12.4. Analytical Solution for Dilute Systems: Kremser Equation 490

12.5. Efficiencies 496

12.6. McCabe-Thiele Analysis for More Concentrated Systems 497

12.7. Column Diameter 501

12.8. Dilute Multisolute Absorbers and Strippers 502

12.9. Matrix Solution for Concentrated Absorbers and Strippers 504

12.10. Irreversible Absorption and Cocurrent Cascades 508

References 510

Homework 511

Appendix. Computer Simulations of Absorption and Stripping 520

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**Chapter 13: Liquid-Liquid Extraction 527**

13.0. Summaryâ€”Objectives 527

13.1. Extraction Processes and Equipment 527

13.2. Dilute, Immiscible, Countercurrent Extraction 532

13.3. Dilute Fractional Extraction 539

13.4. Immiscible Single-Stage and Cross-Flow Extraction 543

13.5. Concentrated Immiscible Extraction 547

13.6. Immiscible Batch Extraction 551

13.7. Extraction Equilibrium for Partially Miscible Ternary Systems 553

13.8. Mixing Calculations and the Lever-Arm Rule 556

13.9. Partially Miscible Single-Stage and Cross-Flow Systems 558

13.10. Countercurrent Extraction Cascades for Partially Miscible Systems 561

13.11. Relationship Between McCabe-Thiele and Triangular Diagrams for Partially Miscible Systems 569

13.12. Minimum Solvent Rate for partially Miscible Systems 570

13.13. Extraction Computer Simulations 572

13.14. Design of Mixer-Settlers 573

References 586

Homework 588

Appendix. Computer Simulation of Extraction 598

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**Chapter 14: Washing, Leaching, and Supercritical Extraction 603**

14.0. Summaryâ€”Objectives 603

14.1. Generalized McCabe-Thiele and Kremser Procedures 603

14.2. Washing 606

14.3. Leaching with Constant Flow Rates 610

14.4. Leaching with Variable Flow Rates 612

14.5. Introduction to Supercritical Fluid Extraction 615

14.6. Application of McCabe-Thiele and Kremser Methods to Other Separations 617

References 618

Homework 619

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**Chapter 15: Introduction to Diffusion and Mass Transfer 627**

15.0. Summaryâ€“Objectives 629

15.1. Molecular Movement Leads to Mass Transfer 629

15.2. Fickian Model of Diffusivity 631

15.3. Values and Correlations for Fickian Binary Diffusivities 647

15.4. Linear Driving-Force Model of Mass Transfer for Binary Systems 656

15.5. Correlations for Mass Transfer Coefficients 670

15.6. Difficulties with Fickian Diffusion Model 682

15.7. Maxwell-Stefan Model of Diffusion and Mass Transfer 683

15.8. Advantages and Disadvantages of Different Diffusion and Mass Transfer Models 698

References 698

Homework 700

Appendix. Spreadsheets Examples 15-10 and 15-11 707

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**Chapter 16: Mass Transfer Analysis for Distillation, Absorption, Stripping, and Extraction 711**

16.0. Summaryâ€”Objectives 711

16.1. HTU-NTU Analysis of Packed Distillation Columns 712

16.2. Relationship of HETP and HTU 720

16.3. Mass Transfer Correlations for Packed Towers 723

16.4. HTU-NTU Analysis of Concentrated Absorbers and Strippers 731

16.5. HTU-NTU Analysis of Cocurrent Absorbers 736

16.6. Prediction of Distillation Tray Efficiency 738

16.7. Mass Transfer Analysis of Extraction 741

16.8. Rate-Based Analysis of Distillation 753

References 756

Homework 758

Appendix. Computer Rate-Based Simulation of Distillation 765

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**Chapter 17: Crystallization from Solution 769**

17.0. Summaryâ€“Objectives 769

17.1. Basic Principles of Crystallization from Solution 770

17.2. Continuous Cooling Crystallizers 776

17.3. Evaporative and Vacuum Crystallizers 785

17.4. Sieve Analysis 793

17.5. Introduction to Population Balances 798

17.6. Crystal Size Distributions for MSMPR Crystallizers 800

17.7 Seeding 814

17.8. Batch and Semibatch Crystallization 820

17.9. Precipitation 825

References 828

Homework 830

Appendix. Spreadsheets 836

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**Chapter 18: Introduction to Membrane Separation Processes 837**

18.0. Summaryâ€”Objectives 838

18.1. Membrane Separation Equipment 840

18.2. Membrane Concepts 843

18.3. Gas Permeation 845

18.4. Reverse Osmosis (RO) 862

18.5. Ultrafiltration (UF) 877

18.6. Pervaporation (Pervap) 883

18.7. Bulk Flow Pattern Effects 895

References 899

Homework 901

Appendix. Spreadsheet for Crossflow Gas Permeation 914

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**Chapter 19: Introduction to Adsorption, Chromatography, and Ion Exchange 917**

19.0. Summaryâ€”Objectives 918

19.1. Sorbents and Sorption Equilibrium 918

19.2. Solute Movement Analysis for Linear Systems: Basics and Applications to Chromatography 930

19.3. Solute Movement Analysis for Linear Systems: Temperature and Pressure Swing Adsorption and Simulated Moving Beds 938

19.4. Nonlinear Solute Movement Analysis 961

19.5. Ion Exchange 970

19.6. Mass and Energy Transfer in Packed Beds 978

19.7. Mass Transfer Solutions for Linear Systems 985

19.8. LUB Approach for Nonlinear Sorption Systems 993

19.9. Checklist for Practical Design and Operation 998

References 1000

Homework 1003

Appendix. Aspen Chromatography Simulator 1019

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Appendix A: Aspen Plus Troubleshooting Guide for Separations 1047

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Appendix B: Instructions for Fitting VLE and LLE Data with Aspen Plus 1051

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Appendix C: Unit Conversions and Physical Constants 1053

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Appendix D: Data Locations 1055

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Answers to Selected Problems 1065

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*Index 1073*

**Phillip C. Wankat** is the Clifton L. Lovell Distinguished Professor of Chemical Engineering and Engineering Education at Purdue University. His research interests include adsorption, large-scale chromatography, simulated moving bed systems, distillation, and improvements in engineering education. He received Purdue Universityâ€™s highest faculty award, the Morrill Award, in 2016. With K. S. Knaebel, he contributed the Mass Transfer section to *Perryâ€™s Chemical Engineersâ€™ Handbook, Eighth Edition*Â (McGraw-Hill, 2008).

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