Effects of residence time on selective absorption of hydrogen sulphide using methyldiethanolamine

Selective absorption of hydrogen sulphide (H 2 S) using methyldiethanolamine (MDEA) has become a point of interest as means of minimising capital and operating costs of gas sweetening plants. This paper discusses the prominence of optimum design of column internals to best achieve H 2 S selectivity using MDEA. To this end, a kinetics-based process simulation model has been developed for a commercial gas sweetening unit. Trends of sweet gas H 2 S and CO 2 contents as function of fraction active area (and hence residence time) have been explained through analysis of interdependent heat and mass transfer phenomena. Guidelines for column internals design in order to achieve desired degree of H 2 S selectivity are provided. Also, the effectiveness of various operating conditions in achieving H 2 S selectivity for an industrial absorber with fixed internals is investigated.