Kinetic modeling of thermal reactor in Claus process using CHEMKIN-PRO software

Abstract We reported a kinetic modeling of thermal reactor in Claus process using CHEMKIN-PRO software. Five hypothetical acid gases with different H2S and NH3 contents were selected and analyzed with a focus on the reaction kinetics occurring in thermal reactor. Modeling results revealed that temperature in thermal reactor initially increased due to the facile oxidation of H2S and NH3, after which it maintained a constant value due to the competing pyrolysis and S2 formation reactions. These patterns lead to equilibrium temperature and gas composition at the reactor outlet. At this point, the reactor outlet temperature and gas composition were greatly affected by the ratio of H2S/NH3 in the acid gases. Accordingly, the ratio of H2S/SO2 in the outlet gas flowing into the subsequent catalytic reactor of the Claus process was changed, necessitating an appropriate process operation. Based on these results, we suggest that the Claus process can be properly controlled by adjusting the air flow rate according to H2S/NH3 ratio. The results indicated that the ratio of H2S/SO2 in the outlet gas decreased with increasing air flow rate. It is expected that the Claus process efficiency can be improved by appropriately controlling the air flow rate in correspondence with H2S/NH3 ratio.