Experimental study on tar destruction in a two stage fixed-bed reactor

Methods of thermal cracking, partial oxidation and char bed conversion on tar destruction has been investigated by a two stage fixed-bed reactor, effects of fuel type, temperature, residence time, char particle size and char type on tar destruction are considered. The result indicates that tar conversion efficiency increase with the second stage reactor temperature increasing in all three kinds of conversion methods. Partial oxidation and char bed conversion is more effective in tar destruction compared to thermal cracking. Associated with partial oxidation and thermal cracking, char bed can get least tar yield. Three kinds of biomass tar yield in the experimental condition of 1 000 ℃ is: rice straw 0.43%, corn straw 0.61% and fir sawdust 1.15%, and the corresponding tar conversion efficiency is 98.28%, 97.23% and 96.29% respectively. Tar yield content of each conversion methods are decreasing with reactor temperature increase. It is really difficult to removal all tar completely in these experiments due to complex tar composition and experimental conditions. The results also show that biomass tar destruction feasibility are: rice straw > corn straw>fir sawdust, and on obvious diversity is obtained between different char species on tar destruction.