Upgrading of waste derived solid fuel by steam gasification

Compared to the incineration, thermolysis can be considered as an interesting alternative or complementary way to eliminate the municipal solid waste or other kinds of dispersed waste, especially in rural regions with a low population density. The economic feasability of the thermolysis depends mainly on the energetic valorization of the solid fuel generated by the process: steam gasification, in selected conditions to avoid toxic metals emissions, is a possible way to valorize this fuel. The results presented here show that steam gasification of waste derived solid fuel produces a synthesis gas with good calorific value. The behaviour of Pb, Cd, Cu and Mn has been studied as a function of the gasification conditions. The main toxic species can be trapped in the ashes in a non-leachable form if kaolinite is added as sorbent during the gasification. The behaviour of the Pb derivative present in the waste derived solid fuel seems to be due to PbCl2 formation during the thermolysis. As an alternative to combustion, energetic valorization of waste derived solid fuel can be considered either by local small scale gasification as well as by co-gasification with coal, rich in kaolinite, in new IGCC processes. (C) 1997 Elsevier Science Ltd.