Thermodynamic equilibrium analysis of hydrogen production by coal based on Coal/CaO/H2O gasification system

Thermodynamic analysis of Coal/H2O/CaO gasification system was investigated for hydrogen production. The influences of gasifier operation temperature, pressure and coal type, H2O/C on hydrogen production were studied based on chemical equilibrium calculation. The operation pressure in the gasifier should be 20–30 bar from CO2 partial pressure and capture efficiency studies. The proper temperature of the gasifier should be between 625–850∘C where more than 70% H2 can be obtained. Xiaolongtan coal has the lowest hydrogen fraction for introducing amounts of CH4 into the reaction system. Carbon conversion in the gasifier was 0.68, while other carbon was burned in regenerator to provide the needed heat for CaCO3 decomposition. Hydrogen production efficiency of 46.45% was achieved by Huainan coal at H2O/C=3H2O/C=3 in the gasifier and regeneration system, which has 85.9% H2 in product gas. The flow balance of mass and enthalpy about the gasifier and regenerator system was also investigated.