Thermal conversion efficiency of producing hydrogen enriched syngas from biomass steam gasification

This paper presents the results from an experimental study on the energy conversion efficiency of producing hydrogen enriched syngas through uncatalyzed steam biomass gasification. Wood pellets were gasified using a 100 kWth fluidized bed gasifier at temperatures up to 850 °C. The syngas hydrogen concentration and cold gas efficiency were found to increase with both bed temperature and steam to biomass weight ratio, reaching a maximum of 51% and 124% respectively. The overall energy conversion to syngas (based on heating value) also increased with bed temperature but was inversely proportional to the steam to biomass ratio. The maximum energy conversion to syngas was found to be 68%. The conversion of energy to hydrogen (by heating value) increased with gasifier temperature and gas residence time, but was found to be independent of the S/B ratio. The maximum conversion of all energy sources to hydrogen was found to be 25%.