Technical Investigation of Integrated Gas Sweetening and Enrichment Process

The duty of Sulfur Recovery Unit (SRU) is converting the acid gas coming from the gas sweetening unit to Sulfur, to prevent the emission of environment pollutant gases. Low H2S concentration in the feedstock may lead to problems such as unstable flame in the reaction furnace, inactivity of catalysts, decrease of sulfur product and increase of environmental pollutants, and reducing the quality of producted sulfur. Therefore, preparing facilities for enrichment of acid gas and increasing the H2S concentration in the feedstock of SRU is necessary. At this time, the H2S concentration in the feedstock of SRU in the south Pars refineries is significantly decreased. Therefore, since the gas sweetening unit is operating under its nominal throughput due to decrease in the H2S concentration of its feedstock, using the excess capacity of this unit for enrichment of the acid gas routed to SRU is applicable. In this papert, at first the gas sweetening unit is simulated by means of the operating data. Then, with considering the enrichment absorber column, an integrated system for increasing the H2S concentration routed to SRU is recommended and simulated. The results shows that increasing the H2S concentration from 20 mol% up to 34 mol% is achievable by applying the unused capacity of the gas sweetening unit and adding just one absorber column.