Study of the effect of hydrogen sulfide in combustion processes of different gas mixtures, and its impact on the emission of pollutants

Conventional natural gas, as well as different non-conventional fuel mixtures or biogas generated in anaerobic digestion, may contain different amounts of hydrogen sulfide in its composition. Nowadays, an important tendency involves not to pretreat the raw gases and to devote the main effort to the development of technologies and combustion processes, together with the dowstream cleaning of the gases.

During the combustion of those mixtures, hydrogen sulfide is oxidized mainly to sulfur dioxide and during that conversion process, it can interact with hydrocarbons thus modifying their conversion regime and/or the emissions of pollutants, both of sulfur compounds and unburned compounds, including soot and polycyclic aromatic hydrocarbons (PAH).

In this context, the main objective of the project is the knowledge of the effect of the presence of hydrogen sulfide in combustions processes of different gas mixtures, both on the conversion of the mixtures and on the formation of pollutants. The oxidation of H₂S will be studied, and temperature, stoichiometry, and pressure (from atmospheric to 60 bar) will be varied. Also, the conversion of hydrocarbon gas mixtures simulating natural gas, non-conventional gas, sour gas and biogas, in the presence of H₂S will be analyzed. For those gas mixtures, the influence of sulfur compounds (H₂S) on the generation of unburned products, soot and PAH will be evaluated.

The studies made in the frame of the present project, both from experimental and modeling points of view, will allow us to determine both the kinetic mechanism of H₂S oxidation as well as the mechanism of the oxidation for the conversion of the different mixtures and for the formation of pollutants under different operating conditions. Additionally, the detailed reaction mechanisms developed and validated in the present project will constitute a useful tool in order to be applied in the simulation of the conversion process of different gas mixtures of industrial interest, for representative conditions of real combustion chambers and processes.