Modelling of an entrained flow coal gasifier. 1. Development of the model and general predictions

Abstract A one-dimensional, steady-state model for an entrained flow coal gasifier is developed, incorporating thermogravimetric analysis data on a bituminous coal. The model is based on mass and energy balances, heterogeneous reaction rates and homogeneous gas-phase equilibria. The resulting set of non-linear mixed ordinary differential-implicit algebraic equations was solved by a modified Euler method in conjunction with a non-linear algebraic equation solver. Temperature, reaction rate and composition profiles in a tubular gasifier were predicted at 0.1 and 2 MPa operating pressures, at constant feed rates. Realistic conversions of carbon could not be predicted if the devolatilization reaction and the heterogeneous surface reactions between the coal and oxygen and steam were assumed to proceed sequentially. The model showed that as the combustion was much faster than the gasification, temperature maxima for both the particles and the gas occurred at the point of final consumption of oxygen. The gasification proceeded only in the absence of oxygen.