Numerical simulation of gas-solid flow in a precalciner of cement industry

Precalciner, in which endothermic raw meal calcination and exothermic fuel combustion proceed simultaneously, is a key equipment in dry process of cement production. To increase the precalcination degree and reduce the energy consumption, more and more attentions have been paid on modeling gas-solid flow field in precalciners. However, most of them aimed at just qualitative studies lacking in necessary further quantitative analysis of precalciner performance parameters. In this paper, combining qualitative studies and quantitative analysis, the gas-solid flow field was carried out aiming at an actual precalciner under operational-based boundary conditions. In Euler coordinate system the gas phase is expressed with k-epsilon model, in Lagrange coordinate system the solid phase is expressed with Discrete Phase Model(DPM), and the random effects of turbulence on the particle dispersion is accounted for with Discrete Random Walk (DRW) model. The predicted gas velocity field agrees well with the measured result, and the calculated raw meal concentration distribution is consistent with the actul condition. The results predicted that there is a simple spraying-liked flow field in the precalciner, with not only a non-uniform particle dispersion condition but also a low solid residence-time and residence-time ratio between solid and gas.