Analysis and optimization for chemical absorption of H2S/CO2 system: Applied in a multiple gas feeds sweetening process

Abstract

Sweetening process is essential in removing H2S and CO2 from refinery gases for environmental and safety concerns. In industrial production, owing to the investment cost, multiple sour gases with various compositions are premixed and sent to a single sweetening plant, leading to unnecessary energy consumption caused by ignoring characteristics of each sour gas. Therefore, the multiple gas feeds absorption was analyzed through orthogonal test method and sensitivity analysis. Moreover, a pre-allocation of raw gases along with multi-feeding operation was proposed to optimize the temperature and concentration distribution in the absorber, so that the mass transfer was significantly strengthened. Based on this, a sweetening process with multiple gas feeds was developed to realize the simultaneous optimization of mass and energy. The rigorous simulation was carried out and the model validity had been verified with experimental and industrial data. Finally, a refinery in Shandong, China was taken as an example. With the proposed process, the purity of H2S in acid gas was increased by 2.55%, while the energy consumption and the overall exergy loss were reduced by 6.5% and 18.75%, respectively.