The Process Simulation And H₂S Concentration Retrofit Of The Rectisol Setup Of A Plant

The rectisol wash is a typical physical absorption method that takes advantage of the superiorities of low-temperature methanol to remove acid gas from the feed gas. For its high degree of purification and good selectivity, this technology is widely used at home and abroad in the gas purification devices of synthetic ammonia, methanol synthesis, and other industrial hydrogen production, desulfurization of city gas and natural gas.A plant used to use Claus Furnace to process the sulfur recovery gas and recycle sulfur powder. Now in order to improve the economic benefits, the plant plans to apply new technology to produce dimethyl sulfoxide. The new technology applied requires to improve H2S content in the original sulfur recovery gas.Applying the general chemical process simulation software Aspen Plus, this paper selects the physical property method of PSRK to simulate the whole process of the rectisol setup of the plant. The simulation results coincide with the practical values. Based on the process model, this paper proposes three retrofit schemes with their comparison to meet the plant’s requirement of increasing the H2S content in the sulfur recovery gas. The results after retrofit show that through properly adding the quantity of the stripping gas N2and regulating the bypass flow rate of the splitter installed on the main N2flow, the H2S content in the sulfur recovery gas can be effectively improved. Among the three schemes, except that the retrofit effect of scheme Ⅰ is inconspicuous, scheme Ⅱ and Ⅲ increase the H2S content in the sulfur recovery gas by1.4times and1.46times respectively, and all the retrofit schemes meet the technology and environment requirements.In addition, along with the simulation and optimization, this paper compares the two functions of sensitivity analysis and design specs in Aspen Plus software. It is discovered that by effectively use these two functions together, the workload can be reduced sharply, which improves the efficiency, and also more accurate results can be obtained.