Modeling of carbon dioxide and hydrogen sulfide pollutants absorption in wetted-wire columns with alkanolamines

Abstract

Abstract In this work, the modeling of flow equations and associated transported phenomena in wetted-wire columns (WWC) has been carried out by using the CFD method. The studied processes in this column included the absorption of H2S and CO2 gases from the gas stream by absorbent solution. In this regard, laboratory results were available only for CO2 absorption in a column with a single wire or 109 wires. Moreover, the fact that modeling of a wetted-wire column needs robust hardware. As a result, firstly, the process of CO2 absorption with monoethanolamine (MEA) solution in a column with a wire was modeled by COMSOL Multiphysics version 5.6. Then, the results of various parameters were compared with laboratory results (the error percentage was calculated to be 2.4%). It was observed that by increasing the liquid flow rate, the distance between the beads decreased and beads with larger diameters and higher velocities formed. Meanwhile, for the first time, the temperature profile inside the column was determined along the column, the temperature of the liquid phase increased. The gas stream after a slight increase in temperature, left the column with a temperature close to the incoming liquid. After model validation, other processes were investigated, resulting from changing desired gas for separation or liquid solution. Finally, different absorbents’ abilities were predicted to absorb gaseous pollutants and obtained that in terms of absorption efficiency, second-type alkanolamines perform better than other types in the simultaneous absorption of CO2 and H2S.