串行流化床气化是一种崭新的气化技术,可将气化和燃烧过程分隔开,气化反应器和燃烧反应器之间依靠惰性固体载热体进行热量传递。以水蒸气为气化介质,在小型串行流化床试验装置上进行生物质气化制取合成气的试验研究,探讨气化反应器温度T、水蒸气与生物质比率S/B对气化结果的影响。试验结果表明,燃烧反应器内燃烧烟气不会串混至气化反应器,该气化技术能够稳定连续地从气化反应器获得不含N2的高品质合成气。随着气化反应器温度的提高,合成气中Ф(H2)/Ф(CO)减小,合成气产率增加,热值降低,总碳转换率先升高而后保持不变。随着S/B的增大,合成气产率和总碳转换率均先升高而后降低,S/B的最佳值为1-4。在试验阶段获得的最高合成气产率为1.87m^3/kg,合成气热值为13.20MJ/m^3,总碳转化率为91%。
High quality syngas production in interconnected fluidized beds of biomass gasification was investigated experimentally. The gasification-required heat was achieved by means of the external recirculation of inert particles in interconnected fluidized beds. The effects of gasifier temperature and steam/biomass ratio on syngas composition, syngas yield, syngas heating value, and total carbon conversion were discussed. The results indicate that the flue gas of combustion and the syngas of gasification are never mixed, and high quality syngas which is free of N2 dilution can be obtained from the gasifier. With the increase of gasifier temperature, Ф(H2)/Ф(CO) decreases, syngas yield increases, and heating value of syngas decreases, total carbon conversion increases remarkably with the gasifier temperature at the lower temperature range 720 to 820 ℃, and reaches its maximum of 91% at the gasifier temperature of 820 ℃, and then keeps nearly constant. There is an optimal value of steam/biomass ratio corresponding to maximal syngas yield and total carbon conversion. For the gasifier temperature of 820℃, syngas yield and total carbon conversion reach their maximum at the steam/biomass ratio of 1.4, and then decrease with the further increase of steam/biomass ratio. The maximum syngas yield and heating value can be attained 1.87 m^3/kg and 13.20MJ/m^3, respectively.