Modified three-dimensional percolation simulation of char fragmentation and particulate formation

The current numerical calculation of particulate formation during char combustion mainly adopts thetwo-dimensional model. In this paper, based on the introduction of the concept ofdiffusion depth,the char combustion is simulated with a three-dimensional model. The modifiedmodel can simulate the actual situation that the reactant gas dose not diffuse into thechar completely. The approach to realize the combustion process of char in chemical controlled zone (zone I) andtransitional controlled zone (zone II) is given, and the results are compared withthose in the diffusioncontrolled zone(zone III). The characteristic impact of initial porosity and mineral content onparticulate formation in different zones is analyzed through the simulation andcomparison. It can be seen from the results that the diffusion depth do put somelimits on char fragmentation and mass distribution of ash particulates, which providestheoretical basis for the further study of particulate formation during charcombustion andthe reduction of particulate emission