Local concentrations of gases in the jetting fluidized bed coal gasifier, particularly in the grid zone of the bed were measured to discuss gas exchange between the jet and annulus and local progress of chemical reactions. Air was introduced from the gas injection nozzle and steam was introduced from the coneshaped distributor plate. Gas exchange between the annulus and the jet rapidly occurred. Compared with the case that only steam was introduced, it was found that air introduced from the nozzle produced carbon oxides at around the boundary of the jet and as a result decreased the rate of steam gasification in the annulus. Both for physical and chemical phenomena the grid zone cannot be regarded as uniform. The grid structure strongly influenced the performance of the gasifier.
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