Experimental study on coal gasification in interconnected fluidized bed

Gasification of coal in a novel interconnected fluidized bed was proposed in this paper.The novel fluidized bed resembled a high velocity circulating fluidized bed in combination with a bubbling fluidized bed after a cyclone.The circulating fluidized bed was designed for coal combustion fed with air,the bubbling fluidized bed was for coal gasification fed with steam.The heat required for gasification was supplied by means of the circulation of inert heat carrier particles.Direct contact between the gasification and combustion processes was avoided.The experiments of coal gasification were performed in a laboratory apparatus of interconnected fluidized bed,and high quality syngas was produced free of N2 dilution.The effects of gasifier temperature and steam/coal ratio on gas composition,heating value,cold gas efficiency and total carbon conversion were discussed.The experimental results indicated that with the increase of gasifier temperature and steam/coal ratio,both heating value and cold gas efficiency increased rapidly.Total carbon conversion increased remarkably with the gasifier temperature at the lower temperature range of 900—950℃,and reached its maximum of 92% at the gasifier temperature of 950℃,and then kept nearly constant.The steam/coal ratio had little effect on the variation of total carbon conversion in the process of coal gasification in the novel interconnected fluidized bed.The maximum heating value and cold gas efficiency could reach 6.9 MJ·m-3 and 68%,respectively.