Study of oxidation for gas mixture of H2S and CH4 in a non-premixed flame under oxygen deficient condition

Oxidation process of gas mixture of hydrogen sulfide (H2S) and methane (CH4) in a non-premixed flame and formation of COS and CS2 has been studied under oxygen deficient condition. Premixed fuel consisting of H2S and CH4 with constant molar ratios (1:1) was injected and air was varied from the stoichiometric to the fuel rich condition (equivalence ratio, Φ = 2) to determine the influence of Φ upon the oxidation manner. The flame could be divided into three sections namely initial oxidation, intense combustion and post-flame section. Oxidation competition between H2S and CH4 was observed at the first section wherein H2S conversion, mainly via partial oxidation, was superior to that of CH4. Initial CH4 conversion involved partial oxidation and interaction with sulfur species which contributed to productions of COS and CS2. Formation of SO2 was witnessed at the second section together with significant increase in concentrations of CO, H2 and C2H2. However, the productions of these combustibles were favored by higher temperature and fuel rich condition and likely to be maintained under anoxic environment in the post-flame section. The CS2 and COS concentration profiles suggested a tight relationship between its conversion path and the O2 level downstream.