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Modeling and simulation of the desulfurization of a sour gas streams by adsorption: Influence of the isotherm model

dos Santos João Paulo Lobo (Federal University of Sergipe, Petroleum Engineering Core, São Cristóvão, Brazil)
de Lima Cunha Acto (Federal University of Sergipe, Petroleum Engineering Core São Cristóvão, Brazil)
de Lobato Ana Katerine Carvalho Lima (Federal University of Bahia, Postgraduate Program of Chemical Engineering, Salvador, Brazil)
Moraes Caetano (Federal University of Rio de Janeiro, Department of Chemical Engineering, Rio de Janeiro Brazil)
Baptista Severo João Júnior (Federal University of Sergipe, Department of Chemical Engineering, São Cristóvão, Brazil)
dos Santos Luiz Carlos Lobato (Federal University of Bahia, Department of Materials Science and Technology, Salvador Brazil)

The presence of elemental sulfur (S8) in natural gas streams has caused several problems at the delivery points, one of the most recurrent being the deposit of "yellow powder" in the pilots of pressure control valves. The presence of H2S in the natural gas stream may serve as the source for the S8 and/or increase the solubility thereof in the gas. Studies have shown that adsorption control mechanisms are more attractive for use in pipelines to control S8 deposition. In this study, computational simulations were performed in the software COMSOL Multiphysics, using the computational fluid dynamics (CFD) technique and 13X zeolite as adsorbent. The isotherm models of Langmuir, BET, Freundlich, Toth and Sips were tested in the modeling and simulation and the results obtained showed that the isotherm models presented the following decreasing order of precision in relation to the experimental results: Sips = = Freundlich > Toth > Langmuir > BET. In addition, it was possible to verify that the variation of the coefficient of axial dispersion significantly influences the size of the mass transfer zone.

Keywords: natural gas, elementar sulfur, desulfurization methods, adsorption, CFD simulation