Distillation Design and Control Using Aspen Simulation

by Luyben, William L.

• ISBN13: 9781118411438
• ISBN10: 1118411439
• Edition: 2nd
• Format: Hardcover
• Copyright: 2013-04-29
• Publisher: Wiley-AIChE

Summary

This book uses the commercial simulator Aspen Plus to develop rigorous simulations of single distillation columns and sequences of columns. Methods are illustrated for designing the economic optimum distillation column from a steady-state standpoint. Total annual cost, which includes both capital and energy costs, is used as the objective function to be minimized. Other issues such as robustness to disturbances and sensitivity to uncertainties in physical properties, tray efficiencies and market requirements are also considered. Another unique feature is coverage of the design and control of petroleum fractionators, which is non-existent in any design books. Aspen Dynamics are then used to explore the dynamics of these designs and to develop effective control structures. The new edition updates and expands on the first edition and adds new chapters on the divided wall column a more widely applied method and carbon dioxide capture from stack gas. Also discussed is the use of dynamic simulation to study safety issues (high pressure and temperatures) in the event of operating failures (loss of cooling water), an update on the discussion of Aspen Plus analysis tools for ternary distillation columns and azeotropic separation, and a discussion of control structures and process configurations for handling the very significant column turndowns (very low feed flowrates) required in chemical plants coupled with power generation processes or inherently intermittent "green" energy sources (solar and wind).

Author Biography

WILLIAM L. LUYBEN, PhD, is Professor of Chemical Engineering at Lehigh University where he has taught for over forty-five years. Dr. Luyben spent nine years as an engineer with Exxon and DuPont. He has published fourteen books and more than 250 original research papers. Dr. Luyben is a 2003 recipient of the Computing Practice Award from the CAST Division of the AIChE. He was elected to the Process Control Hall of Fame in 2005. In 2011, the Separations Division of the AIChE recognized his contributions to distillation technology by a special honors session.

Table of Contents

Preface

Chapter 1 – Fundamentals of VLE

1.1 Vapor pressure

1.2 Binary VLE phase diagrams

1.3 Physical property methods

1.4 Relative volatility

1.5 Bubblepoint calculations

1.6 Ternary diagrams

1.7 VLE non-ideality

1.8 Residue curves for ternary systems

1.9 Distillation Boundaries

1.10 Conclusion

Chapter 2 – Analysis of Distillation Columns

2.1 Design degrees of freedom

2.2 Binary McCabe-Thiele method

2.3 Approximate multi-component methods

2.4 Conceptual design of ternary systems

2.5 Conclusion

Chapter 3 – Setting  Up a Steady-State Simulation

3.1 Configuring a new simulation

3.2 Specifying chemical components and physical properties

3.3 Specifying stream properties

3.4 Specifying parameters of equipment

3.5 Running the simulation

3.6 Using design spec/vary function

3.7 Finding the optimum feed tray and minimum conditions

3.8 Column sizing

3.9 Using Conceptual Design

3.10 Conclusion

Chapter 4 – Distillation Economic Optimization

4.1 Heuristic optimization

4.2 Economic basis

4.3 Results

4.4 Operating optimization

4.5 Optimum pressure for vacuum columns

4.6 Conclusion

Chapter 5 – More Complex Distillation Systems

5.1 Extractive distillation

5.2 Heterogeneous azeotropic distillation

5.3 Pressure-swing azeotropic distillation

5.4 Heat-integrated columns

5.5 Conclusion

Chapter 6 – Steady-State Calculations for Control Structure Selection

6.1 Control structure alternatives

6.2 Feed-composition sensitivity analysis

6.3 Temperature control tray selection

6.4 Conclusion

Chapter 7 – Converting from Steady State to Dynamic Simulation

7.1 Equipment sizing

7.2 Exporting to Aspen Dynamics

7.3 Opening the dynamic simulation in Aspen Dynamics

7.4 Installing basic controllers

7.5 Installing temperature and composition controllers

7.6 Performance evaluation

7.7 Conclusion

Chapter 8 – Control of More Complex Columns

8.1 Extractive distillation process

8.2 Columns with partial condensers

8.3 Control of heat-integrated distillation columns

8.4 Control of azeotropic columns/decanter system

8.5 Unusual Control Structure

8.6 Conclusion

Chapter 9 – Reactive Distillation

9.1 Introduction

9.2 Types of reactive distillation systems

9.3 TAME process basics

9.4 TAME reaction kinetics and VLE

9.5 Plantwide control structure

9.6 Conclusion

Chapter 10 – Control of Sidestream Columns

10.1 Liquid sidestream column

10.2 Vapor sidestream column

10.3 Liquid sidestream column with stripper

10.4 Vapor sidestream column with rectifier

10.5 Sidestream purge column

10.6 Conclusion

Chapter 11 – Control of Petroleum Fractionators

11.1 Petroleum fractions

11.2 Characterization of crude oil             

11.3 Steady-state design of preflash column

11.4 Control of preflash column

11.5 Steady-state design of pipestill

11.6 Control of pipestill

11.7 Conclusion

Chapter 12 – Design and Control of Divided-Wall Columns

12.1 Introduction

12.2 Steady-state design

12.3 Control of divided-wall columns

12.4 Control of conventional column process

12.5 Conclusion and Discussion

Chapter 13 – Dynamic Safety Analysis

13.1 – Introduction

13.2 – Safety scenarios

13.3 – Process studied

13.4 – Basic Radfrac models

13.5 Dynamic simulations

13.6 Comparison of dynamic responses

13.7 Other Issues

13.8 Conclusion

Chapter 14 – Carbon Dioxide Capture

14.1 – Carbon dioxide removal in low-pressure air combustion power plants

14.2 – Carbon dioxide removal in high-pressure IGCC power plants

14.3 – Conclusion

Chapter 15 – Distillation Turndown

15.1 Introduction

15.2 Control problem

15.3 Process studied

15.4 Dynamic Performance for ramp disturbances

15.5 Dynamic performance for step disturbances

15.6 Other control structures

15.7 Conclusion

Chapter 16 – Pressure-Compensated Temperature Control in Distillation Columns

16.1 Introduction

16.2 Numerical example studied

16.3 Conventional control structure selection

16.4 Temperature/pressure/composition relationships

16.5 Implementation in Aspen Dynamics

16.6 Comparison of dynamic results

16.7 Conclusion