Catalytic steam gasification of lignite with olivine as solid heat carrier

Catalytic coal gasification was carried on a lab-scale external circulating co-current moving-bed (ECCMB) gasification system with steam as gasification agent and olivine as catalytic solid heat carrier. The system is composed of a moving-bed gasifier and a riser combustor. The effects of gasifier temperature, steam/coal mass ratio (S/C), bed materials and bed height on the product gas compositions, carbon conversion, and chemical efficiency were investigated. The result show that the gas yield and carbon conversion increase with the increase of the gasifier temperature. The highest H2 concentration of 60.4 vol.% is produced from Dayan lignite at the gasifier temperature of 800 °C and S/C ratio of 1.0. The carbon conversion increases remarkably at the S/C range from 0 to 0.4. Olivine as the bed material has a satisfying catalytic tar cracking efficiency. Appropriate bed height favors tar destruction because of the increase in the contact time of the tar and steam with the catalytic bed material.