A process simulation study of hydrogen and sulfur production from hydrogen sulfide using the Fe–Cl hybrid process

• Idemitsu–Kosan (IKC) hybrid Fe–Cl process is modeled.
• IKC process is used to produce S and H2 from H2S.
• The simulation model is validated against pilot-scale plant data.
• The simulation model is used to investigate the process performance.
• The suitability of the IKC process to replace Claus process is proved.

Presently, most of the acid gas (H2S) streams from amine gas sweetening and refinery upgrading operations are treated using the modified Claus process. In this process, sulfur and low-quality steam are produced by partial oxidation of H2S. Despite the modified Claus process's success in accomplishing the above tasks, it still has some disadvantages. Additional tail gas treatment unit is needed to improve its efficiency. Also, a valuable commodity, hydrogen, is not recovered.In this work, a process simulation study on the Idemitsu Kosan Co. Fe–Cl hybrid process is carried out. The process is capable of producing sulfur and hydrogen from H2S gas streams. The process was modeled and validated using pilot-scale plant data before been scaled up using the typical acid gas composition profile of one of Abu Dhabi's sulfur recovery plants. The effects the absorber solution flow rate and concentration have on the process’ operability were investigated. Operating at high ferric ions concentration was found to be more beneficial compared to high solution flow rate operations. The ferrous ion constituent of the solution proves to be instrumental in the downstream electrolysis process. Cost estimates of the process indicate the suitability of the process to be implemented in Abu Dhabi gas plants to produce sulfur, and most importantly, hydrogen to be used as fuel or chemical feedstock.

Simplified flow diagram of the Fe–Cl hybrid process. Figure optionsDownload as PowerPoint slide