Conversion characteristics of a single coal char particle with high porosity moving in a hot O2/CO2 atmosphere

Abstract

The conversion characteristics of a single particle with high porosity moving in a high temperature O2/CO2 atmosphere were simulated to complement the particle conversion sub-model. Considering the significant changes in the pore structure of high porosity particles, the effects of the high porosity (0.5–0.9) on conversion process were investigated. According to the experimental studies, two different types of char structures were considered for the particles with different porosity to establish the particle structure model, which include large pore structure and cenosphere structure. The reaction model contains water-gas-shift reaction, CO oxidation reaction and four heterogeneous reactions. The results show that the diffusion of the species is less limited inside the particle when the particle porosity is higher than 0.8. With the increase of particle size, the surface temperature and temperature gradient decrease. With the increase of the particle porosity, the surface temperature decreases and the temperature gradient increases. In addition, the specific carbon consumption rates decrease along with the increase of the particle size. When the particle porosity increases, the specific carbon consumption rates decrease firstly then significantly increase.