Particle Resolved Thermo-Chemical Conversion of Pulverized Coal Clusters

Abstract

Particle clusters form in the turbulent flow of boilers and furnaces when injecting pulverized coal. We study the difference in conversion behavior between a pul verized coal cluster and a single char particle. The simulations are done using a detailed particle model in OpenFOAM.The detailed particle model is capable of spatially resolv ing char particles and solving transport equations for heat and mass inside the particles. Furthermore, a surface chemistry model is employed for modeling gas-solid reactions in side the pores of the particles. The char particles are coupled to the surrounding bulk fluid phase using explicit Robert-Neuman coupling. 2-D simulations are carried out for a cluster of 16 particles and a single particle. Both simulations use the same initial con ditions, boundary conditions and particle properties. The results indicate that a lack of oxygen penetration toward the center of the particle cluster alters the thermo-chemical conversion behavior when compared to the single particle. On average this leads to a decrease of the thermo-chemical conversion rates for particles in the cluster, resulting in a reduction of solid carbon consumption compared to the same number of single particles.