Effect of process conditions on tar formation from thermal reactions of ethylene

Thermal reactions of ethylene were studied to understand better the effect of process conditions on tar formation in biomass gasification. The effects of pressure, residence time and temperature on thermal reactions of ethylene were studied. The analysis of products from methane up to pyrene was performed by the novel online GC method. Ethylene conversion increased linearly as a function of pressure and residence time. Tar formation increased exponentially in the pressure range 1-3.5 bar and linearly with the residence time. The fraction of heavier tar compounds was found to increase with temperature and pressure. The tar composition was compared with different biomass gasification tar compositions, and the compositions were found to resemble each other. The obtained tar-laden product gas could be used as a realistic tar model when the cleaning of biomass gasification gas is studied.