Process integration of sulfur combustion with claus SRU for enhanced hydrogen production from acid gas

Abstract

The commercial Claus sulfur recovery process is intended for treating H2S present in acid gas by recovering sulfur. During this process, hydrogen present in H2S is inadvertently converted to low grade steam. In the current study, an improved technique for recovering hydrogen and sulfur from acid gas containing H2S was developed using Aspen HYSYS®. Hydrogen production by thermal decomposition of H2S was achieved in the tubes of a waste heat exchanger connected in-series with a reaction furnace and followed by Claus sulfur recovery unit (SRU). The energy requirement for the decomposition reaction was supplied through elemental sulfur combustion in the reaction furnace. While H2S decomposition was defined by a kinetic model in a plug flow reactor, sulfur combustion and H2S-SO2 combustion processes were described using Sulsim™ Sulfur Recovery model in Aspen HYSYS®. A commercial Claus sulfur recovery unit (SRU) located in Abu Dhabi was considered for process development. Two different process integration schemes differing in hydrogen recovery layout design were analyzed. Based on various performance indicators, including hydrogen and sulfur yields, H2S conversion rate, and sulfur combustion rate, the most feasible process configuration for maximizing overall process efficiency was identified. The proposed integrated process has the capability for generating hydrogen yield as high as 33% and a simultaneous sulfur recovery of nearly 99%. In addition, the developed processes can significantly curtail the handling load on catalytic section by 11.3% and 16%, respectively, in terms of catalyst bed volume.