The Numerical Simulation Study Of The Flow Field And Combustion In A Precalciner

Precalciner is the key equipment of the new type dry-process cement production system,it is not only a combustion furnace but also a chemical reaction equipment, Mufti-phase flow, combustion of fuel, heat transfer,decomposition of carbonate co-exist in it. In precalciner, the fluid parameters, such as concentration distribution, kinetic velocity, stay-time of materiel and fluid velocity, pressure and temperature distribution of gas-phase have a lot of relations to the properties of the combustion of pulverized coal and the decomposition of carbonate. The main chemical reactions in aprecalciner, namely the combustion of pulverized coal and the decomposition of carbonate, occur in a suspending state,and the structure of precalciner make it very difficult to research precalcine.These years with the rapid development of the technology of computer hard ware and software, the numerical simulation technology based on Computational Fluid Dynamics (CFD) develops quickly and increasingly becomes matured. Due to being proved truly by the high precise numerical forecasts of flow, heat transference, combustion, chemical reaction, multiphase flow in many engineering practices in high technology industry such as aviation spaceflight etc, the numerical simulation increasingly becomes popularized and adopted in many other engineering industries.In this paper ,the CFD commercial software, Fluent6.2.16, was adopted to simulate the gas-solid two-phase flow and coal combustion in the precalciner, and the main results are as follows:(1)The three-dimension turbulence flow in the precalciner was simulated by the Realizable k-εmodel and SIMPLE methods, By the method of numerical simulation to study the flow field in precalciner,which set up a good foundation for later researching.(2) The three-dimension turbulence flow and combustion in the precalciner was simulated, The gas phase flow is expressed with Realizable k-εmodel, The movement of raw material and coal particle is simulated by the particle stochastic trajectory model, The gas combustion is expressed with the Mixture-Fraction/PDF model, coal combustion is expressed with the kinetics/diffusion—limited rate model, released rate of the volatiles is expressed with the constant rates model, radiation of the combustion is expressed with the P-1 radiation model. by analysis of the simulation result,we get the results of sporting in precalciner.(3) By analysis of the all flows field structure of the precalciner, and studying advantage and disadvantage of the precalciner structure, some further improvement and optimization have been put forward.