Modelling of fluidised-bed coal gasifiers: elimination of the combustion product distribution coefficient by considering homogeneous combustion

Effect of the combustion product distribution coefficient, phi, in the char partial combustion reaction on modelling of fluidised-bed coal gasifiers h as been investigated for two cases with and without considering homogeneous gas phase combustion in the model, respectively. Simulations incorporating homogeneous combustion of gases indicate that phi value between 0.55 and 0 .95 has little influence on the predicted operating temperatures, total car bon conversions, gas production rates and compositions of the gasifiers sim ulated. These results also compare well with experiments. However, for simu lations without homogeneous combustion, rb does significantly affect the mo delling predictions, and the simulation results compare poorly with experim ents. The results suggest that homogeneous combustion of combustible gases should be incorporated in fluidised-bed coal gasifier models, and in the ab sence of any experimental data, phi can be chosen between 0.75 and 0.85 for simulations with negligible effect on model predictions. (C) 2000 Elsevier Science S.A. All rights reserved.