CO2 Removal by Amine Absorption and Condensed Rotational Separation: Energy Consumption & Equipment Sizing
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CO2 removal by Amine Absorption and Condensed Rotational Separation: Energy Consumption & Equipment Sizing by STEVEN JAN MARTIN DE RIJKE BSc in Mechanical Engineering THESIS submitted in partial fulfillment of the requirements for the degree MASTER OF SCIENCE: MECHANICAL ENGINEERING Department of Mechanical Engineering Technical University Eindhoven Document Number: WPT201214 November 30, 2012 Approved by: prof. dr ir J.J.H. Brouwers dr. ir H.P. van Kemenade prof.dr. M. Golombok dr.ir. J. van der Schaaf Acknowledgment The author wishes to thank J.J.H. Brouwers & H.P. van Kemenade for the idea for this work and their support throughout the process R.J. van Benthum for his insightful help and his time Romico Hold for access to proprietary knowledge regarding the RPS and related processes. J.M. de Rijke & E.A. de Rijke-Amesz for their patience and support ii SUMMARY/ABSTRACT The Rotational Particle Separator (RPS) is a compact device capable of separating micron-sized droplets from gases by centrifugation. Combined with expansion cooling in a turbine at semi-cryogenic temperatures, it provides the opportunity to remove contaminants like CO2 and H2S from natural gas. Potential advantages of this technique are lower energy consumption and compactness. To demonstrate its potential, the technology is compared on the basis of installed volume and energy consumption with conventional amine technology for a range of CO2 concentrations. The comparison is made using a model of both processes and their components separating a range of CO2 contents from a 125 MMscf/day gas stream. The results show that for CO2 concentrations greater than 15% the CRS technology offers significant advantages in both installed volume and energy requirement, unlocking natural gas fields with sour gas concentrations that cannot be treated with conventional technology up until well in the 70% CO2 content. iii Table of Contents 1 COMPARISON OF CONDENSED ROTATIONAL SEPARATION WITH AMINE GAS SWEETENING ............................................................................................................................................. 6 2 ASSUMED PROCESS PROPERTIES ............................................................................................. 6 3 AMINE GAS SWEETENING ........................................................................................................... 8 3.1 ENERGY ............................................................................................................................................ 8 3.2 VOLUME ........................................................................................................................................... 9 4 CONDENSED ROTATIONAL SEPARATION ............................................................................ 14 4.1 CRS AS BULK SEPARATOR IN COMBINATION WITH AN AMINE ABSORPTION PLANT. ....................... 14 4.2 METHANE LOSS .............................................................................................................................. 14 4.3 ENERGY .......................................................................................................................................... 15 4.4 VOLUME ......................................................................................................................................... 15 5 COMPARISON RESULTS .............................................................................................................. 17 5.1 ENERGY .......................................................................................................................................... 17 5.2 VOLUME ......................................................................................................................................... 21 6 CONCLUSIONS AND RECOMMENDATIONS .......................................................................... 22 APPENDIX A TABLES AND GRAPHS .......................................................................................... 23 APPENDIX B AMINES TREATING – PROCESS DESCRIPTION AND COMPONENTS ......... 30 B.1 PROCESS OVERVIEW .................................................................................................................. 31 B.2 ABSORPTION OPERATING PRINCIPLES ........................................................................................ 31 B.2.1 Straight Dissolution of Absorbate......................................................................................... 32 B.2.1.1 Solubility .................................................................................................................................... 32 B.2.1.2 Gas and Liquid Concentration Equilibrium lines - Henry’s Law ............................................... 33 B.2.2 Dissolution accompanied by irreversible chemical reaction ................................................ 35 B.2.2.1 Chemical reaction with Amines ................................................................................................. 35 B.3 STRIPPING OPERATING PRINCIPLES ............................................................................................ 36 B.4 AMINES ...................................................................................................................................... 37 B.4.1 Alkanolamine Solvents .......................................................................................................... 37 B.4.2 Other solvents used in gas treating ....................................................................................... 38 B.4.2.1 Hindered amine technology ....................................................................................................... 39 B.4.2.2 Physical Solvent Processes ........................................................................................................ 39 B.4.2.3 Mixed Chemical/Physical Solvent Processes ............................................................................. 39 B.4.3 Amine Concentration ............................................................................................................ 40 B.4.4 Amine Loading ...................................................................................................................... 41 B.5 ABSORBER AND STRIPPER COLUMNS .......................................................................................... 42 B.5.1 Packed Bed Columns ............................................................................................................ 43 B.5.1.1 Types of Random Packing ......................................................................................................... 44 B.5.1.2 Liquid Distribution. .................................................................................................................... 46 B.5.2 Tray Columns ....................................................................................................................... 47 B.5.3 Spray Tower Absorbers ........................................................................................................ 49 B.6 KETTLE REBOILER ..................................................................................................................... 50 B.6.1 Operating Principles ............................................................................................................ 51 B.6.2 Combination with Reclaimer ................................................................................................ 51 B.7 AMINE RECLAIMER .................................................................................................................... 51 B.7.1 Mea concentration step ......................................................................................................... 53 B.7.2 Steady-State Boiling Step ...................................................................................................... 53 B.7.3 MEA Recovery Step .............................................................................................................. 53 B.7.4 Reclaimer Cleaning / Shutdown Procedure .......................................................................... 54 B.8 OTHER COMPONENTS COMMON TO MOST AMINE SYSTEMS ...................................................... 55 1 B.8.1 Inlet Gas Knockout Drum ..................................................................................................... 55 B.8.2 Three Phase Flash Tank ....................................................................................................... 56 B.8.3 Lean/Rich Heat Exchanger ................................................................................................... 58 B.8.4 Filtration ............................................................................................................................... 58 B.8.5 Mist Eliminators ................................................................................................................... 59 B.8.5.1 Operating principle .................................................................................................................... 59 B.8.5.2 Capacity Limits .......................................................................................................................... 63 B.8.6 Pumps ................................................................................................................................... 65 B.9 OPERATING DIFFICULTIES .........................................................................................................