The change of the physical properties of coal char during reaction

A bifurcated cylindrical pore model has been developed to simulate the change of the physical properties of coal char during gasification or combustion. This model demonstrates that changes in the pore structure of coal char can be characterized by dividing the pores into micropores and macropores. Because the micropores provide most of the char surface area, the change in the surface area can be simulated by using a single size micropore model. The evolution of surface areas predicted by the bifurcated pore model agrees well with the experimental data. The model further illustrates that under kinetic control, the combustion characteristic curve is a function of the initial micropore porosity. For char with very small initial micropore porosity, a single (master) curve can characterize the combustion behaviour of coal char.