The Claus reactors is widely used to recover elementary sulfur from hydrogen sulfide that is contained in fresh natural gas. It involves thermal oxidation of hydrogen sulfide and its reaction with sulfur dioxide to form sulfur and water vapor. To improve the efficiency of the process, we built two kinds of 3-dimensional Claus reactor models to explore the key factors that affect the combustion reactions. The two-channel Claus reactor consisted of an air channel and an acid gas channel (60% H2S, 33% CO2, 7%H2O) while the three-channel Claus reactor consisted of two air channels and an acid gas channel (60% H2S, 33% CO2, 7%H2O). The two-channel model was built according to the devices used in the factory while the three-channel model was improved by us from the two-channel model. In both the two models, air and acid gas turned into swirling flow in their channels respectively before their mixture. Then air and acid gas mixed and burned at the throat of the models. The most remarkable difference between the two kinds of Claus reactors was that the three-channel reactor had an additional inner air channel inside the acid gas channel that can be helpful to the mix of the acid gas and air. The second difference was that the two kinds of reactors had different deflectors to swirl in the flow fields. In this study, we compared the flow fields and concentration fields of the two kinds of Claus reactors by using a computational fluid dynamics (CFD) tool.
The simulation results indicated that the swirling intensity and the mix intensity played an important role in the combustion reactions. The efficiency of sulfur recovery in Claus reactors increased with an increase of the swirling intensity or the mix intensity. The stronger the swirling intensity or the mix intensity was, the sooner the mixture of air and acid gas reached to the best stoichiometric ratio. The three-channel reactor had a better performance than that of the two-channel reactor due to the additional inner air channel which can strengthen the mix of the acid gas and air from the inside of the acid gas. Moreover, the helix deflectors in the three-channel reactor had a better swirling performance than that of the vane deflectors in the two-channel reactor. From the comparison of the two models, we can obtain a way to improve the process of elementary sulfur recovery in the industry, which can be helpful to reduce pollution emissions and improve economic performance.