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

Effect of the combustion product distribution coefficient, φ, in the char partial combustion reaction on modelling of fluidised-bed coal gasifiers has 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 φ value between 0.55 and 0.95 has little influence on the predicted operating temperatures, total carbon conversions, gas production rates and compositions of the gasifiers simulated. These results also compare well with experiments. However, for simulations without homogeneous combustion, φ does significantly affect the modelling predictions, and the simulation results compare poorly with experiments. The results suggest that homogeneous combustion of combustible gases should be incorporated in fluidised-bed coal gasifier models, and in the absence of any experimental data, φ can be chosen between 0.75 and 0.85 for simulations with negligible effect on model predictions.