Experimental investigation on hydrogen production from biomass gasification in interconnected fluidized beds

摘要

Hydrogen production from biomass gasification was performed in a laboratory scale apparatus of interconnected fluidized beds in this paper. It resembles a high velocity fluidized bed with a spout-fluid bed after a cyclone. The high velocity fluidized bed is designed for a combustor, the spout-fluid bed for a gasifier. Biomass particles with steam are introduced into the bottom of the spout-fluid bed. It favors the process of hydrogen production from biomass gasification, as well as tar decomposition. The gasification-required heat was achieved by means of the external recirculation of bed particles in interconnected fluidized beds. Direct contact between the gasification and combustion processes is avoided. The effects of gasifier temperature and steam/biomass ratio on the composition of hydrogen-rich gas, carbon gasification of biomass, carbon combustion of biomass, carbon utilization of biomass, tar content and hydrocarbons were discussed. The results indicated that both a relatively high hydrogen content and a great hydrogen yield were obtained from biomass gasification in interconnected fluidized beds. With the increase of gasifier temperature, H_2 content decreased, CO increased evidently with the gasifier temperature. The steam/biomass ratio has a weak effect on the syngas composition. There was an optimal value of steam/biomass ratio corresponding to maximal hydrogen yield. For the gasifier temperature of 820℃, hydrogen yield and carbon gasification of biomass reached its maximum values of 0.S53 Nm~3kg~(-1) biomass and 50.02% at the steam/biomass of 1.4, and then decreased with the further increase of steam/biomass ratio.