The fate of methane in the reaction furnace of a modified Claus plant

This thesis reports a thermodynamic feasibility study and experimental kinetic data for key side reactions occurring in the front end [i.e. the reaction furnace (RF) and the waste heat boiler (WHB)] of modified Claus plants used for sulfur recovery from the sour gases evolved in the treatment of natural gas. Ultimately, this work will enable the front end of a Claus plant to be simulated in order to minimize sulfur emissions.;An extensive experimental study was conducted for three important homogenous gas-phase reactions. First, the oxidation of hydrogen sulfide was investigated with three initial oxygen concentrations. The main purpose of this first study was to gather some experimental information and to enhance understanding of the H2S oxidation reaction prior to tackling a more complicated system (i.e. oxidation of H2S and CH4 mixtures). Second, experiments were conducted to study the oxidation of hydrogen sulfide and methane mixtures in the presence of oxygen. Lastly, the reaction between methane and sulfur dioxide was investigated experimentally. The experimental results showed that methane was much less competitive for oxygen in comparison to hydrogen sulfide. Hence, in a partially oxidizing environment, experimental data showed that methane reacted with other major sulfur containing species in secondary reactions to form COS and, especially, CS2 significantly. This is highly problematic from an environmental point of view because these two compounds contribute to sulfur emissions in a major way.