Removal of CO2 and H2S using Aqueous Alkanolamine Solusions

Authors: Zare Aliabad, H., Mirzaei, S.

Abstract:

This work presents a theoretical investigation of the simultaneous absorption of CO2 and H2S into aqueous solutions of MDEA and DEA. In this process the acid components react with the basic alkanolamine solution via an exothermic, reversible reaction in a gas/liquid absorber. The use of amine solvents for gas sweetening has been investigated using process simulation programs called HYSYS and ASPEN. We use Electrolyte NRTL and Amine Package and Amines (experimental) equation of state. The effects of temperature and circulation rate and amine concentration and packed column and murphree efficiency on the rate of absorption were studied. When lean amine flow and concentration increase, CO2 and H2S absorption increase too. With the improvement of inlet amine temperature in absorber, CO2 and H2S penetrate to upper stages of absorber and absorption of acid gases in absorber decreases. The CO2 concentration in the clean gas can be greatly influenced by the packing height, whereas for the H2S concentration in the clean gas the packing height plays a minor role. HYSYS software can not estimate murphree efficiency correctly and it applies the same contributions in all diagrams for HYSYS software. By improvement in murphree efficiency, maximum temperature of absorber decrease and the location of reaction transfer to the stages of bottoms absorber and the absorption of acid gases increase.

Keywords: Absorber, DEA, MDEA, Simulation.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1085489

References:

[1] H. Mackenzie Douglas, A. Daniels Christina, "Design & Operation of a Selective Sweetening Plant Using MDEA", Bryan Research & Engineering, Inc., 1987.
[2] P.J.G. Huttenhuis, N.J. Agrawal, J.A. Hogendoorn, and G.F. Versteeg, "Gas solubility of H2S and CO2 in aqueous solutions of N-methyl diethanol amine", Journal of Petroleum Science and Engineering, 2007, 55,122-134.
[3] B.P Mandal, S.S Bandyopadhyay, "Simultaneous absorption of carbon dioxide and hydrogen sulfide into aqueous blends of 2-amino-2-methyl- 1-propanol and diethanol amine", Chemical Engineering Science, 2005, 60, 6438-6451.
[4] A.L. Kohl, F.C. Riesenfeld, Gas Purification. 4th ed., Gulf Publishing Company, Houston, 1985.
[5] B.P. Mandal, A.K. Biswas, and S.S. Bandyopadhyay, "Selective absorption of H2S from gas streams containing H2S and CO2 in aqueous solutions of N-methyldiethanolamine and 2-amino-2-methyl-1- propanol", Separation and Purification Technology 35,2004a, 191-202.
[6] C.Polasek John, A.Iglesias-Silva Gustavo, "Using Mixed Amine Solutions for Gas Sweetening",Bryan Research & Engineering , Inc.,1992.
[7] R. Maddox, "Gas and Liquid Sweetening" , Second edition , Campbell, 1977.
[8] P. V. Danckwerts, "The Reaction of CO2 with Ethanolamines," Chem. Eng. Sci., 1981, 34, 443, 1979.
[9] D. W. Savage, E.W. Funk, "Selective Absorption of H2S and CO2 into Aqueous Solutions of Methyldiethanolamine," AIChE meeting, Houston, Texas, April 5-9, 1981.
[10] C.C. Chen, H.I. Brit, J.F. Boston, and L.B. Evans, "A local composition model for the excess Gibbs energy of aqueous electrolyte systems: part I: single solvent, single completely dissociated electrolyte system", AICHE J., 1982, 4, 588-596.
[11] Markus Bolhar-Nordenkampf, Anton Friedl, Ulrich Koss, and Thomas Tork, "Modelling selective H2S absorption and desorption in an aqueous MDEA-solution using a rate-based non-equilibrium approach", Chemical Engineering and processing, 2004, 43,701-715.
[12] G. Vallee, P. Mougine, S. julian, and W. Furst, Representation of CO2 and H2S absorption by aqueous solutions of diethanolamine using an electrolyte equation of state, Ind. Eng. Chem. Res.,1999, 38,3473-3480.