PhD thesis under common supervision presented for obtaining THE TITLE OF PHD OF THE INSTITUT NATIONAL POLITECHNIQUE DE TOULOUSE Doctoral school: Mécanique, Energétique, Génie civil, & Procédés Specialty: Process engineering and THE TITLE OF PHD OF THE BUDAPEST UNIVERSITY OF TECHNOLOGY AND ECONOMICS Doctoral school: Pattantyús-Ábrahám Géza Mechanical Sciences by László HÉGELY chemical engineer IMPROVEMENT OF BATCH DISTILLATION SEPARATION OF AZEOTROPIC MIXTURES Supervisors: Péter LÁNG DSc, Budapest University of Technology and Economics Vincent GERBAUD HDR, Institut National Polytechnique de Toulouse 2013 2 Acknowledgement This PhD thesis is the result of my research work performed under common supervision at the Department of Building Services and Process Engineering of the Budapest University of Technology and Economics and at the Laboratoire de Génie Chimique of Institut National Politechnique de Toulouse. First of all, I would like to thank my supervisors Prof. Péter Láng and Vincent Gerbaud for receiving me as a PhD student in Hungary and in France, respectively. They were always ready to help me, to discuss and correct my works, even though they are both very busy. I also thank Gábor Modla and Ferenc Dénes, members of our research group in Budapest for their help and their ideas, and to Máté Erdős for his technical help with the figures of my thesis. I thank Márta Láng-Lázi for starting me in the world of research and teaching me Maple. I also thank Ivonne Rodríguez-Donis for her interest in my work and for our discussions. I would like to thank the French Embassy in Hungary for their scholarship, which made my studies in France possible. It is impossible to mention all the colleagues and friends in Toulouse, yet my special thanks go to Sofí and Marco for all their amity and support. Finally, I would like to say many thanks to my parents who always supported me and to my friends in Hungary who were patient with me. 3 4 Table of contents Notation ................................................................................................................................... 10 General Introduction ............................................................................................................. 13 1. Literature Review ............................................................................................................ 16 1.1. Phase Equilibria .................................................................................................... 17 1.1.1. Equilibrium relations .......................................................................................... 17 1.1.1.1. γ – ϕ Approach ........................................................................................... 17 1.1.1.2. ϕ – ϕ Approach .......................................................................................... 19 1.1.1.3. γ – γ Approach ........................................................................................... 19 1.1.2. Azeotropic Binary Mixtures ................................................................................ 19 1.1.3. Ternary Mixtures................................................................................................. 23 1.1.3.1. Residue Curve Maps and Their Classification .......................................... 23 1.1.3.2. Unidistribution and Univolatility Lines ..................................................... 27 1.2. Zeotropic and Homoazeotropic Distillation ....................................................... 28 1.2.1. Continuous Homoazeotropic Distillation ........................................................... 28 1.2.2. Homogeneous Batch Distillation ........................................................................ 30 1.2.2.1. Operational Policies ................................................................................... 30 1.2.2.2. Product Sequences for Azeotropic Distillation ......................................... 31 1.2.2.3. Non-Conventional Configurations ............................................................ 34 1.2.2.4. Off-Cut Recycle ......................................................................................... 37 1.3. Homoextractive Distillation ................................................................................. 38 1.3.1. The Role and Selection of the Entrainer ............................................................. 38 1.3.2. Continuous Homoextractive Distillation ............................................................ 40 1.3.3. Batch Homoextractive Distillation...................................................................... 41 1.4. Heteroazeotropic Distillation ............................................................................... 43 1.4.1. Continuous Heteroazeotropic Distillation .......................................................... 43 1.4.2. Batch Heteroazeotropic Distillation ................................................................... 44 1.5. Heterogeneous Extractive Distillation ................................................................ 46 1.5.1. Continuous Heterogeneous Extractive Distillation ............................................ 46 1.5.2. Batch Heterogeneous Extractive Distillation ..................................................... 47 1.6. Pressure Swing Distillation .................................................................................. 48 1.6.1. Continuous Pressure Swing Distillation ............................................................. 48 1.6.2. Batch Pressure Swing Distillation ...................................................................... 49 5 1.7. Other Distillation Methods .................................................................................. 50 1.7.1. Hybrid (Distillation+Absorption) Process ......................................................... 50 1.7.2. Salt-Effect Distillation......................................................................................... 51 2. Algorithm and Program for the Determination of Product Sequences in Azeotropic Batch Distillation ............................................................................................................. 52 2.1. Description of the Algorithm ............................................................................... 53 2.1.1. Step 1: Determination of the Type of All Stationary Points ................................ 55 2.1.1.1. Step 1a: Determination of the Type of Stationary Points in Each Ternary Submixture ................................................................................................... 55 2.1.1.2. Step 1b: Unification of Ternary Submixtures to Quaternary Ones ........... 58 2.1.1.3. Step 1c: Unification to Submixtures of Higher Dimension ....................... 59 2.1.2. Step 2: Completion of Adjacency Matrix ............................................................ 59 2.1.3. Step 3: Determination of Product Sequences ..................................................... 61 2.1.4. Managing Heteroazeotropes and Pressure Change ........................................... 63 2.2. Results .................................................................................................................... 63 2.2.1. Calculations for Mixture 1 .................................................................................. 63 2.2.2. Calculations for Mixture 2 .................................................................................. 67 2.3. Conclusions ........................................................................................................... 69 3. Closed Batch Distillation ................................................................................................ 71 3.1. Configurations and Operation Modes Studied .................................................. 72 3.1.1. Batch Rectifier (Two-Vessel Column) ................................................................. 72 3.1.1.1. Open Operation Mode ............................................................................... 72 3.1.1.2. Closed Operation Modes ........................................................................... 73 3.1.1.2.1. Mode 1: constant volumetric flow rate ............................................................74 3.1.1.2.2. Mode 2: constant level .....................................................................................74 3.1.1.2.3. Mode 1: constant liquid flow rate, then constant level ....................................75 3.1.1.2.4. Mode 4: temperature control ...........................................................................75 3.1.2. Middle-Vessel (Three-Vessel) Column ................................................................ 75 3.1.2.1. Comparison of the Open Mode of Batch Rectifier and of Middle-Vessel Column ......................................................................................................... 76 3.1.2.2. Comparison of the Operation Modes of The Middle-Vessel Column....... 77 3.1.3. Multivessel (Four-Vessel) Column...................................................................... 77 3.2. Calculation Results ............................................................................................... 78 3.2.1. Batch Rectifier..................................................................................................... 79 6 3.2.2. Middle-Vessel Column ........................................................................................ 82 3.2.2.1. Comparison of the Open Mode of Batch Rectifier and