Design, Simulation and Optimization of Adsorptive and Chromatographic Separations: A Hands-On Approach

Y.A. Liu, the Alumni Distinguised Professor and the Frank C. Vilbrandt Endowed Professor of Chemical Engineering at Virginia Tech, received his B.S. (1967), M.S. (1970), and Ph.D. (1974) degrees from National Taiwan University, Tufts University and Princeton University, respectively. Professor Liu devoted his school breaks helping petrochemical industries in developing countries and chemical industries in Virginia with technology development and engineering training. He has taught intensive training courses on computer-aided design, advanced process control, energy and water savings, and refinery and polymerization process modeling to over 7,000 practicing engineers in China, Taiwan and United States. Kevin Wood received his Ph.D. in the Department of Chemical Engineering at Virginia Polytechnic Institute and State University (?Virginia Tech?) in June, 2016. He received his B.S. in chemical engineering from Purdue University in 2010. He completed his doctoral dissertation on the development of computational tools for the design of SMB systems, and design of software to enable Aspen simulations to be run in parallel. The tools he developed, and simulations he ran using them, form the basis of this textbook. He has worked on industrial modeling projects, including biodiesel, CO2 capture, and xylene separation. These projects were collaborative efforts between Virginia Tech, Aspen Technology, and industrial partners. Yueying Yu received her Ph.D. in the Department of Chemical Engineering at Virginia Tech in December, 2015. She received her B.S. in chemical engineering from Dalian University of Technology in China in 2009. She completed her doctoral dissertation on the simulation and comparison of operational modes in simulated moving bed (SMB) chromatography and gas-phase adsorptive separation. This is a part of the basis of this book.

• Foreword by George E. Keller, II xiPreface xiiiSoftware Selection and Copyright Notice xviiAcknowledgments xixAbout the Authors xxiList of Computer Files xxiii1 Simulation of Adsorption Processes 11.1 Introduction to Gas-phase Adsorption Technologies 11.2 Core Concepts in Gas Adsorption 21.2.1 The Adsorption Process 21.2.2 How the Driving Forces Achieve Separation 31.3 Isotherms 41.3.1 The Langmuir Isotherm (1918) 51.3.2 The Linear Isotherm 51.3.3 The Brunauer–Emmett–Teller (BET) Isotherm (1938) 51.3.4 The Freundlich Isotherm (1906) 61.3.5 The Sips (Langmuir–Freundlich) Isotherm (1948) 61.3.6 The Toth Isotherm (1971) 61.3.7 Summary 61.4 The Properties of Packed Beds 61.4.1 Void Fractions 71.4.2 External Voids 81.4.3 Internal Voids 81.4.4 Densities 81.4.4.1 Bulk Density 81.4.4.2 Skeletal or Solid Density 91.4.4.3 Envelope or Particle Density 101.4.4.4 Caveats 101.4.5 Relationships 101.4.6 Gas-phase Behavior 101.4.6.1 Pressure Drop 101.4.6.2 Compressibility 111.5 PSA and TSA Implementation Details 121.5.1 Common Adsorbent Characteristics 121.5.2 Common Process Configurations 121.6 Introduction to Aspen Adsorption 131.7 PSAWorkshop: Aspen Adsorption Modeling for Air Separation 151.7.1 Adding Components to an Aspen Adsorption Simulation 171.7.2 Creating a Flowsheet in Aspen Adsorption 221.7.3 Specifying Operating Conditions: Tables and Forms 331.7.4 Scheduling Events with the Cycle Organizer 421.7.5 Running an Aspen Simulation 511.7.6 Viewing and Exporting Simulation Results 511.8 PSAWorkshop: Hydrogen Separation in Aspen Adsorption 571.8.1 Define the Components and Property Model 581.8.2 Creating a Flowsheet in Aspen Adsorption 631.8.3 Run a Breakthrough Simulation 651.8.4 Create the PSA Flowsheet 771.9 PSAWorkshop: Modeling Hydrogen Separation using gCSS 871.9.1 Define the Components and Property Models 911.9.2 Working with Model Libraries: Advanced Flowsheet Options 951.9.3 Introduction to Scripting: Set Repeated Values and Initialize Blocks 1081.9.4 Inspecting Blocks: Advanced Operating Conditions 1121.9.5 Defining the Cycle Organizer 1191.9.6 Viewing Results 1271.10 TSAWorkshop: Temperature Swing Adsorption for Air Drying 1281.11 Conclusions 1401.12 Practice Problems 1431.12.1 Introducing a gas_interaction Unit intoWorkshop 1 1431.12.2 Naphtha Upgrading Using Adsorption 1451.13 Nomenclature 149Bibliography 1502 Simulation of SMB Chromatographic Processes 1552.1 Introduction to Chromatography 1552.1.1 Mathematical Differences from Gas Adsorption 1552.1.1.1 The Trace Liquid Assumption 1552.1.1.2 Concentration Versus Partial Pressure 1562.1.2 Thermodynamic Differences from Gas Adsorption 1562.1.2.1 Isotherms 1562.1.2.2 Physical Property Models 1562.2 Introduction to SMB Chromatography 1562.3 SMB Implementation Details 1572.3.1 Common Process Configurations 1572.3.2 M-Values 1602.3.3 Scale-Up Concerns 1612.3.4 Pressure Drop Limitations 1622.3.5 Introduction to OperationalModes 1632.4 SMBWorkshop: Simulate a Four-Zone SMB in Aspen Chromatography for the Separation of Tröger’s Base Enantiomers 1632.4.1 Creating a Flowsheet in Aspen Chromatography 1632.4.2 Adding Components to an Aspen Chromatography Simulation 1642.4.3 The Chrom_CCC_separator2 Block 1652.4.4 Viewing Results 1882.5 Tandem SMBWorkshop: Simulate a Separation with Dual SMB Columns 1922.6 Practice Problems 1942.6.1 RunWorkshop 2.4 as a Steady-State Simulation 1942.6.2 Simulation of an Industrial-Scale Xylene Separation Using Literature Data 2002.6.3 Simulate a Five-Zone SMB System for Separating Phenylalanine, Tryptophan, and Methionine 202 Bibliography 2063 Shortcut Design of SMB Systems 2133.1 General Concepts 2133.1.1 Mass Balances 2153.1.2 Differential Equations 2173.1.3 The Method of Characteristics 2183.2 TriangleTheory 2193.2.1 Notations 2193.2.2 Introduction 2193.2.3 Constraints on the System 2223.3 TriangleTheoryWorkshop: Design of a System for the Separation of Amino Acids 2243.4 Exercise 1: Calculating Transitions in a Fixed Bed Using Mathematica 2303.4.1 Differential Equations – Analysis 2323.4.2 Constructing the Solution from Eigenvectors and Eigenvalues 2383.4.3 Use the Steady-State Information to Constrain Operating3.4.4 Calculate the Curves Defined by the Eigenvectors 2413.4.5 Calculate the Eigenvalues along the Transition 2443.4.6 Calculate the Concentrations in Time and Space 2463.4.7 Account for ShockWaves 2463.5 Exercise 2: Constructing the Constraints on the TMB System in Mathematica 2493.6 StandingWave Design 2533.6.1 StandingWave Design in a Nonlinear Ideal System 2543.6.2 StandingWave Design in a System with Nonlinear Isotherm and Significant Mass Transfer Effects 2613.7 StandingWave DesignWorkshop: Calculating the Operating Conditions for an Ideal and a Nonideal System 2653.8 Conclusions 2713.9 Practice Problems 2723.9.1 Use the TriangleTheory Tool and the StandingWave Design Tool to Create an Aspen Simulation of the Separation of 1-phenol-1-propanol on Tribenzoate 272Bibliography 2744 Operational Modes of SMB Processes 2834.1 Overview 2834.2 Selection of OperationalModes 2844.3 Varicol 2844.3.1 Design Heuristics and Examples 2864.3.2 Workshop 1: Apply Varicol to the 4-Zone SMB Model 2874.4 PowerFeed 2934.4.1 Design Heuristics and Examples 2944.4.2 Workshop 2: Apply PowerFeed to the Four-Zone SMB Model 2974.5 ModiCon 3094.5.1 Design Heuristics and Examples 3094.5.2 Workshop 3: Apply ModiCon to the 4-Zone SMB Model 3154.6 Combined Modes 3234.6.1 Workshop 4: Extend Previously Created Flowsheets 3234.7 Parallel Two Zones 3304.7.1 Introduction to Parallel Two Zones 3304.7.2 Specification Analysis 3344.7.3 Importing Flowsheets 3374.8 Conclusions 3454.9 Practice Problems 3454.9.1 Simulation of a Five-Zone SMB Unit Using the ModiCon Operational Mode 3454.9.2 Compare Parallel Two-Zone Results with SMB Results 345Bibliography 3475 Parameter Estimation, Regression, and Sensitivity of Adsorptive and Chromatographic Processes 3495.1 Empirical Correlations for Physical Properties 3495.1.1 Axial Dispersion Coefficient 3495.1.2 Mass Transfer Coefficient 3505.1.3 Caveats 3515.2 ParameterWorkshop: Regressing against Steady-State Experiments 3515.2.1 Introduction to "Experiments" In Aspen Software 3515.2.2 Experimental Data 3525.2.3 Parameter Regression in Excel 3525.2.4 Parameter Regression in Aspen Chromatography 3635.2.4.1 Defining an Estimation Flowsheet 3635.2.4.2 Entering Experimental Data 3645.2.4.3 Estimation Settings 3685.2.4.4 Running an Estimation 3705.2.5 Parameter Regression In Mathematica 3705.2.5.1 Defining the Functions 3715.2.5.2 Entering the Data 3725.2.5.3 Regression 3755.3 ParameterWorkshop: Regressing Against Dynamic Experiments 3765.3.1 Problem Description 3765.3.2 Dynamic Estimation Settings 3765.3.3 Performance Concerns 3805.4 Xylene Parameter Regression 3805.5 Conclusions 3865.6 Practice Problems 3875.6.1 Perform Dynamic Parameter Estimation in Aspen Adsorption 3875.6.2 Sensitivity Analysis Using Scripts in Aspen Adsorption 389Bibliography 393Literature Cited in the Text 395Index 399