Formation and Catalytic Decomposition of Tars from Fluidized-Bed Gasification

Abstract

This paper describes studies concerning the formation of tars in a pressurized fluidized-bed gasifier and their catalytic decomposition in a separate reactor. In the gasification tests, the effects of fuel and freeboard temperature on tar yields and composition were measured. Finnish peat, saw dust and German brown coal were used as fuels. The tar yields decreased with increasing freeboard temperature. The total tar concentration in wood gasification at 900 °C was in the range of 10-18 g/m3n. In peat gasification the concentration at the same conditions was only 3-6 g/m3n and with brown coal less than 1.5 g/m3n. The main components of tar for all the fuels were benzene and naphthalene.