A numerical simulation of the physico-chemical processes occurring inside a heated rotary kiln reactor, where coal, lignite or biomass are treated in vacuum for the production of cliean solid fuel, has been performed with FLUENT6 Computational Fluid Dynamics (CFD) code. The model accounts for the rotation of the kil walls and mixing blades, multiphase flow modelling of the solid (fuel) and gaseous (mixture of gases) phases, heat transfer between phases and the heated kil walls and mass transfer due to chemical reaction between species of different (heterogeneous) phases. The objective is to contribute towards a reliable numerical methodology as a design tool with reference to the fuel feed properties (e.g. solids size, volatile, carbon and moisture content, feed rate) and process requirements (e.g. desired residence time). Kiln wall erosion is also assessed.

Keywords : Low-temperature carbonisation, Rotary kiln, Computational fluid dynamics