Percolation concepts in modelling of gas-solid reactions—I. Application to char gasification in the kinetic regime

The application of percolation theory to modelling of noncatalytic gas-solid reactions is introduced with particular emphasis on char gasification. A Bethe network description of the pore space topology is developed and justified. This approach provides a natural framework for modelling pore opening, enlargement and coalescence in the evolution of porosity and internal accessible surface area with solid conversion. In addition, the description includes the role of pore topology in the particle disintegration at high conversions. Because of the detailed treatment of basic topological features of the internal pore structure, the model is able to predict experimental observations for a variety of conditions.