Regular Article

Investigating efficiency improvement in sulfur recovery unit using process simulation and numerical modeling

¹ Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47907-2100, USA
² South Pars Gas Complex, 75391/311 Assaluyeh, Iran
³ Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada
⁴ Department of Chemical Engineering, University of Sistan and Baluchestan, 98164-161 Zahedan, Iran

^* Corresponding author: ffarhad@alumni.purdue.edu; farhad.fazlollahi@gmail.com

Received: 23 January 2020
Accepted: 1 December 2020

Abstract

Hydrogen sulfide exists mostly as a detrimental byproduct in the gas processing units as well as refineries, and it must be eliminated from natural gas streams. In a Sulfur Recovery Unit (SRU), hydrogen sulfide is converted into the elemental sulfur during the modified Claus process. Efficiency of sulfur recovery units significantly depends on the reaction furnace temperature. In this work, the effect of oxygen and acid gas enrichment on the reaction furnace temperature and accordingly on sulfur recovery is studied, using both numerical modeling and process simulation. Then, simulation and numerical model are benchmarked against the experimental data of an SRU unit. The validated model provides spotlight on optimizing the upstream sulfur removal unit as well as the oxygen purification process. Two cases of acid gas streams with low and high H₂S content, 30% and 50%, are studied to investigate the effect of operating parameters on the overall recovery. Finally, average errors of the models are presented. According to the absolute difference with experimental values, the developed numerical model shows great potential for accurately estimating overall efficiency of the recovery unit.