Process modelling for the production of hydrogen-rich gas from gasification of coal using oxygen, CO2 and steam reactants

Abstract This process modelling studied the effect of different reactants on syngas composition and gasifier heat duty (heat energy required to carry out the operation) and the downstream treatment of CO rich syngas to maximise hydrogen yield. The process modelling was validated against experimental data obtained from a large bench-scale entrained flow gasifier. Results show that considering the H2/CO ratio, the steam-O2 reactant favours the most compared to those of the pure oxygen and oxygen-CO2 reactants. Under comparable operating conditions, the highest H2/CO ratio of 0.74 was determined using steam-O2 reactant compared to that of 0.31 and 0.33 using steam-CO2 and pure oxygen reactant. The catalytic water-gas shift reaction (WGSR) favours the yield of H2 with complete CO conversion at a temperature of 400 °C using the steam/coal ratio of 1.2. Supplying steam in the gasifier requires more heat energy to be supplied to drive endothermic gasification reaction and maintain the gasifier temperature. Under complete carbon conversion, steam-CO2 and steam-oxygen reactants require 5–65 kW more energy than pure oxygen.