Numerical modelling of an entrained-flow gasification simulator

In order to study the gasification process of coal particles, two small scale Entrained-Flow Gasification simulators have been developed at the Netherlands Energy Research Foundation (ECN). The Atmospheric Entrained-Flow Gasification Combustion simulator (AEFGC-simulator) offers the possibility to study gasification and combustion processes experimentally at atmospheric pressures. With the Pressurized Entrained-Flow Gasification simulator (PEFG-simulator) the conditions during the gasification process at high pressures can be simulated experimentally. Both simulators consist of a circular tube with three concentric inlets: two burners and an annular inlet for a co-flow. Coal particles can be inserted through the centre burner into the simulator. It is possible to use several gas mixtures up to a pressure of 20 bar (only for the PEFG-simulator) by varying the operational conditions of the burners. To select appropriate experimental settings, a numerical model has been developed to predict the composition and temperature of the gas phase within the simulators without particles. The model focusses on the mixing and reaction processes within the simulators. The inlet boundary conditions are computed by a separate combustion code, while the reactions within the simulator are assumed to be diffusion limited. All the important coefficients are temperature and mixture dependent. Due to the high concentration of radiating species (CO, CO₂ and H₂O) gas radiation is important. The absorption coefficient is determined using the Edwards exponential wide band model. Comparison of the preliminary modelling results at one bar with the experimental results show that the model predicts the composition and temperatures at the centre axis of the AEFGC-simulator reasonably well, although further research is necessary.