CCSEM analysis of ash from oxyfuel combustion of Zhundong coal

Abstract

The present work was addressed toward the ash characteristic of Zhundong coal using computer-controlled scanning electron microscopy (CCSEM), and discussed the effect of gas phase conditions on the distributions of particle size, minerals, and elements. In this study, Zhundong coal was burned with air and three kinds of oxyfuel conditions in the high-temperature drop-tube furnace. The ash characteristics were measured by CCSEM, which can determine the size, composition, and abundance of minerals in coal and ash on a particle-by-particle basis. The CCSEM results indicated that the mass of fine particles in oxyfuel conditions was less than that in air condition, increased with the O2 concentration and the mass of coarse ash particles in oxyfuel conditions was more than that in air condition, decreased with the O2 concentration. It also can be found that higher particle temperature enhances the co-melting of mineral. Under oxyfuel conditions, the high CO2 concentration not only affects the transformations of coal minerals, but also shortens the decomposition process and extends the oxidation process slightly, which leads to increase in carbonate mineral. The increase in particle temperature can not only enhance the vaporization of refactory oxide, but also enhance interaction of the finely dispersed combined with inherent mineral particles. Avoiding the enrichment of Ca and S in fine particles is a good idea to reduce the ash deposit potential.