Effect of steam supply to the air-blown gasifier on hot syngas desulphurization

Abstract

The IGCC technology serves to efficiently produce thermal and electrical energy with minimal impact on the environment. In operating IGCC, wet desulphurization is used at temperatures below 200°C. The use of hot desulphurization at temperatures around 500°C will significantly improve IGCC efficiency. The preferred sorbent for hot gas cleaning is ZnO. At temperature of 450-500°C, ZnO begins decomposing because of reactions with syngas components (primarily hydrogen). Steam impedes reaction of ZnO with H2 and increases ZnO thermal stability. Syngas H2/H2O ratio is determined by gasifier operation mode. The purpose of this work is to determine maximum temperature of hot gas cleaning depending on condition of ZnO-sorbent thermal stability and steam-air-blown mechanically activated coal gasifier operation mode. To determine the effect of steam supply to syngas composition, experiments were performed on entrained-flow gasifier (1 MW). Experimental results were processed using thermodynamic analysis to determine idealized syngas composition and CFD-modeling to determine real experiment process parameters. Syngas H2O content was determined by CFD-modeling results. Study of ZnO-sorbent thermal stability depending on H2 concentration and syngas H2/H2O ratio was performed by TGA. As a result of experimentally confirmed thermodynamic calculations, ZnO-sorbent thermal stability was found to increase to 815°C due to steam dilution. © Published under licence by IOP Publishing Ltd.