Performance analysis of a biomass gasifier

This paper presents an original modelling of the biomass gasification process and more particularly the wood gasification. Gasification is one of the more efficient ways to convert the energy embedded in the biomass. In the long term, the use of this rather new technology will reduce the too high pressure on the natural resources and that especially in the developing countries. The model based on the minimisation of the Gibbs free energy is performed in the ASPEN PLUS process simulator. The processes occurring in the gasification are here uncoupled in pyrolysis, combustion, Boudouard reaction, and gasification. In the first part of the paper the model is described and the physical meaning of the relevant parameters are given. In the second part, the results of a sensitivity analysis with respect to the oxygen factor, the air temperature, the oxygen content in air, the operating pressure and the injection of steam are presented. From this study, the following conclusions are derived: there exists a critical air temperature above which the preheating is no longer efficient, there is an optimum oxygen factor, the oxygen enrichment of air plays an efficient role under a certain value and the operating pressure has only a slight positive effect on the process efficiency. (C) 2002 Published by Elsevier Science Ltd.