Numerical simulation of gas–solid heat transfer characteristics of porous structure composed of high-temperature particles in moving bed

Abstract

Blast furnace slag is the main by-product of ironmaking, and its waste heat recovery is essential for energy saving. As an excellent gas–solid reactor, moving bed has wide application prospects in waste heat recovery. Nevertheless, most researchers are currently keen on the thermal characteristics of fluidized bed. There is no clear conclusion for gas–solid heat transfer mechanism of moving bed, especially the heat transfer characteristics of particles with multiple particle size distribution. Therefore, in this paper, a CFD-DEM coupling method is used to simulate waste heat recovery process of the blast furnace slag in the moving bed. The gas–solid heat transfer characteristics of a porous structure composed of different particle size distribution systems were studied. The results show that the binary particle size mixing system has the best heat transfer effect. Moreover, the waste heat recovery rate decreases with the increasing initial temperature and mass flow rate of particles, while increases with the increasing bed height and gas flow rate. Based on these results, an empirical correlation of the comprehensive heat transfer coefficient is obtained using the dimensional analysis. The study clarifies multiphase flow and heat transfer characteristics in the moving bed of the porous structure composed of high-temperature slag particles with multiple particle size distribution, and provides a theoretical basis for the next-step development of a high-efficiency gas–solid heat transfer moving bed.