Biomass Gasification in an Air-Blown Down-Draft Gasifier: Determination of Tar Compounds from Producer Gas

The existence of tar compounds in producer gas is one of the major problems found in biomass gasification; these compounds need to be removed before the producer gas can be used. In order to predict the need for producer gas cleaning for catalytic conversion into traffic fuels and chemicals, the gas has to be accurately characterised and defined. In this study, tar compounds from producer gas of two small-scale downdraft gasifiers were collected, identified, and quantified. Based on the results, there were several tar compounds present in the gas flow. Toluene and naphthalene were the most abundant compounds, totalling more than 70% of the total volume of tars while tar concentration levels were in the range of 200 to 400 mg/Nm 3 . These concentrations were found to be consistent with values presented for similar-type gasifiers using wood chips.