A study on wood gasification for low-tar gas production

We present results of an experimental study on two-stage wood gasification and attempts to reduce the tar content of the gas. Increasing the wood-chip moisture content resulted in an increase of CO2 and H2 but a decrease of the CO concentration without significantly affecting the tar content in the producer gas. For a particular primary air flow rate, an increase in the secondary air flow of the two-stage gasifier resulted in decrease of the tar content and the CO2 and H2 concentrations while that of CO increased. A charcoal gasifier and a floating-drum gas-storage system were coupled to a two-stage wood gasifier. The tar content of the product gas was in the range 19–34 mg/Nm3 for a charcoal gasifier coupled to a two-stage wood gasifier. With a floating-drum gas-storage system and a 3.5 h retention time, the tar content was reduced to 9.24 mg/Nm3, which is 85% less than that obtained by using the a two-stage wood gasifier alone.