Simulation of hydrogen sulfide absorption tower using caustic solution and replacement of different packings to reduce caustic consumption

In this study, the selective adsorption is considered by chemical absorption by caustic aqueous solution. This study is based on the simulation with the Aspen-Plus version 9. The rate-based model has been used to determine the separation efficiency for different operating conditions in the simulation. The NRTL electrolytic model is used to describe the non-ideal behavior in liquid phase, while the Soave-Redlich-Kwong equation of state is used for vapor phase. Simulation results show the high efficiency of caustic for the removal of hydrogen sulfide. The results show that the concentration of hydrogen sulfide in the outlet gas from the absorption tower is below 0.5 ppm. It is also discussed about the replacement of different packings and their effect on the reduction of caustic consumption. The results showed that at constant caustic flow rate and concentration, FLEXIMAX-metal 400 packing had better performance in absorbing hydrogen sulfide.