Effect of H₂ on coal-char gasification reaction with steam under pressure

The gasification characteristics of Huolinhe lignite char (HLH char), SM bituminous coal char (SM char) and Jincheng anthracite char (JC char) with the mixtures of steam and H₂ at elevated pressures were investigated in a pressurized fixed bed differential (PFBD) reactor. The results show that the inhibition of H₂ on the coal-char gasification with steam is remarkable, and the intensity of the inhibition increases with increasing H₂ partial pressure, total pressure and coal rank, respectively; while it decreases with increasing temperature. Coal-char gasification with steam or steam/H₂ can be described by the same kinetic model, and the final carbon conversion of coal-char gasification with steam/H₂ is lower than that with steam. The inhibition mechanism is related to the H₂ partial pressure. When H₂ partial pressure is low, H atom dissociated from H₂ molecule occupies the active point on the coal-char surface directly; while when the H₂ partial pressure is high, the irreversible reaction of oxygen-exchange reaction is strengthened.