Understanding the mechanism of ash deposition on boiler heating surface: The lattice Boltzmann and molecular dynamics simulations

Abstract

Severe ash deposition can cause a decrease of the heat transfer ability on the heating surface for the furnace and the release of more pollutants. In order to get the widespread use of Zhundong coal, the temperature distribution characteristics of ash deposition for Zhundong coal was studied by lattice Boltzmann method in this paper. Furthermore, the microstructure of slag was further revealed by molecular dynamics. The results indicated that the temperature of ash deposition improves with the increase of time. The temperature of the particles in the outer and middle layers for Zhundong coal is significantly smaller than that of lignite and bituminous coal. Compared with other coal types, it is difficult to transfer heat for the deposited layer of Zhundong coal, which can not achieve better energy saving effect. Additionally, calcium and sulfur in Zhundong coal ash can easily react to form calcium sulfate, aggravating ash deposition on the heating surface of the boiler. These results provide a theoretical support to solve the problem of ash deposition burning Zhundong coal.