Mathematical modelling and optimization of producing hydrogen-rich gas in COREX melter gasifier

Abstract

The integration of dome injection technology and coal gasification technology can enhance space utilization and generate high-quality reducing gas in the dome of COREX melter gasifier, making it a promising process for hydrogen-rich gas production. In this study, a comprehensive 3-D mathematical model is utilized to depict the inner characteristics with dome coal injection, including flow filed, thermal state, gas composition and particle behavior in the dome of COREX melter gasifier. The results indicate that the flow field in the dome can be categorized into jet flow region, impinging flow region and plug flow region. The gasification performance exhibited significant improvement, particularly the hydrogen production capability, which increased by 2150 Nm3/h. The proportion of C(s) consumed by combustion decreased to 37.32 %, while that of gasification increased to 62.68 %. Without oxygen compensation, the optimal coal injection ratio is determined to be 204.5 kg/t. As the oxygen flow rate through the oxygen burners increases from 1478 Nm3/h to 4478 Nm3/h, the dome temperature rises, advancing the devolatilization process of coal particles and improving combustion efficiency. When CO2 is used as the alternative carrier gas, the proportion of CO in the export gas increases by 0.03 % and that of CO2 increases by 1.11 %. However, when H2O is used as the alternative carrier gas, the proportion of H2 in the export gas increases by 0.35 % and that of H2O increases by 0.89 %.