Simulation of sulfur recovery process and optimization of the main operational parameters

Abstract

Strict environmental regulations has pushed sulfur emissions from natural gas and crude oil refining plants to very low levels. The current and most widely used method for reducing those emissions is the Claus sulfur recovery process, which is not sufficient to satisfy stringent air pollution requirement as the typical standards limit sulfur emission from sulfur recovery plants to 250 ppm. Hydrogen sulfide, which is a byproduct of natural gas and crude oil processing plants, is very poisonous gas and its presence requires great deal of attention in order to meet environmental regulations and pipeline specifications. The most widely used method to treat the acid gas is by absorbing it by amine solvent in an amine sweetening unit followed by sulfur recovery unit. This is essentially recover up to 98 percent sulfur from the acid gas feed. However, with more strict regulations additional processes are required to treat the tail gas by the addition of tail gas treatment unit. The overall sulfur recovery from the integrated Claus sulfur recovery and tail gas treatment units is in the excess of 99.9 percent. ProMax process simulation software was used to model the integrated sulfur recovery process and tail gas treatment unit. The model was then compared and validated against industrial data and a close match was found. Several operating parameters and conditions was then investigated and optimized in order to determine their sensitivity on the performance of the system. Those parameters include but not limited to factors such as the ratio of H2S/SO2 in the tail gas, CO2 slippage, steam stripping ratio, and Claus converters temperature. The addition of SCOT process raised the sulfur recovery efficiency to 99.93% with some modification to operational parameters that have the most influence on the process. The output of the project is to provide a platform for effectively managing the operations of the sulfur recovery process in terms of improving sulfur recovery while minimizing energy and operating cost in order to meet sulfur emission regulations.