Pure Oxygen Combustion Of Acid Gas For Reducing So2 Production in a Normal Diffusion Flame Under Claus Conditions

Abstract

As an auxiliary method in the acid gas (H2S<50.0vol.%) combustion, fuel gas co-combustion (mainly natural gas) generally promoted the SO2 production during the acid gas combustion process, which is unfavorable for improving sulfur recovery efficiency. In this research, the pure oxygen combustion was applied to the acid gas combustion for decreasing SO2 production. Equilibrium model was utilized to preform the thermodynamic analysis of the pure oxygen combustion of acid gas and the CH4 co-combustion of acid gas. The acid gas combustion was conducted in a coaxial jet double channel burner to analyze the distribution of flame temperatures and products along the central axis of reactor in the CH4 co-combustion and pure oxygen combustion, respectively. The results shown that the concentration of SO2 in the pure oxygen combustion of acid gas was much lower than that in the CH4 co-combustion of acid gas, whereas the concentrations of CO and H2 were higher. The H2S flame mainly included the chemical decomposition of H2S and oxidation of H2S, and the chemical decomposition reaction was the main consumption pathway of H2S. The concentration of SO2 could be ignored in the chemical decomposition process, whereas in the oxidation process, it was significantly higher. The SO2 production was mainly through the oxidation reaction or recombination between the sulfur species that released from H2S.

Keywords: Pure oxygen combustion, CH4 co-combustion, Acid gas, SO2 production, Equilibrium model