Received March 31, 2006

Revised Manuscript Received June 29, 2006

Abstract:

A new process of biomass gasification with a catalytic solid heat carrier is proposed that is called the ECCMB (external circulating concurrent moving bed) gasification system. The system is composed of a moving-bed gasification zone and a combustion zone. A circulation loop of bed material, which acts as catalyst and heat carrier, is achieved between these two zones. The char circulated with the bed material and the cokes deposited on the catalyst are burned off in the combustion zone to regenerate the catalyst and provide the energy for the endothermic gasification reactions with steam in the gasification zone. A lab-scale facility was established to demonstrate this process concept, where steam gasification of biomass and combustion of the produced char can occur simultaneously. The H₂ content of 53.3 mol % in dry gas and the tar yield of 0.7 g/Nm³ dry gas can be obtained at a bed height of 400 mm and an S/B ratio (steam/biomass mass ratio) of 0.4 g/g at 800 C with calcined olivine as the catalyst. The results verify that this new concept of biomass gasification for hydrogen-rich gas is feasible. Concurrent moving of biomass and catalyst in the gasification zone is a good solution that enhances the efficiency of the process and decreases the tar yield.

Download the full text: PDF | HTML