In the present paper, the gasification and combustion of wood particles in a cyclone gasifier are studied numerically and the effects of wood particle size and equivalence ratio on the reduction of alkali compounds evaporation and transfer to gas turbine are investigated. The Eulerian conservation equations of gas phase are solved using the control volume approach and the time dependent Lagrangian equations of motion of solid particles are integrated by a semi-analytic method. Results including the distributions of temperature and chemical species, gasification time, particle trajectories and also residence times of wood particles show that for particle sizes ranging from 150 to 600 mm and equivalence ratios between 0.15 and 0.4, satisfactory conditions will be achieved. Particles ,150 mm can transfer the alkali compounds to the gas turbine and particles .600 mm leave the cyclone gasifier without complete char oxidation. Comparisons between numerical and experimental results show good agreement.

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