The Simulation Research Of Ash Vaporization In Pulverized Coal Combustion

Coal is the main primary energy in China and this coal-based energy structurewill not changed in the future. Atmospheric particulate matter pollution is a majorsource of pollution in our cities. The formation of submicron particle mainly fromthe ash vaporization of coal combustion by gasification and condensationmechanism. Submicron particles can be enriched organic pollutants and toxic metalswhich could be harmful to human health and the environment. As ash vaporization isthe source of the formation of submicron, the research of ash transformationbehavior in pulverized coal combustion process is very meaningful.In this paper, after considering the forms of minerals in coals and its transformbehaviors in combustion, assuming that SiO2、Al2O3、FeO、CaO、MgO is the majorminerals in coal, then analyze the influencing factors of minerals vaporization, suchas initial coal particle size, particle temperature and the gas composition. Thencouple minerals vaporization model to CFD software to simulation the ash transformbehaviors in pulverized coal combustion.In this paper, the turbulence model userealizable k–ε model, Lagrangian stochastic tracking model was used to trackparticle trajectories, P-1model and Probability Density Function (PDF) methodwere used to simulate radiation and volatile combustionrespectively.Through the influence of factors on the gasification of minerals indicate thatthe initial particle size of pulverized coal, particle temperature and gas compositionwill have great influence on the vaporization of minerals(SiO2、Al2O3、FeO、CaO andMgO)in coal, But the most important factor for ash vaporization is the combustiontemperature. The CFD simulation in a single-burner furnaceby changing thewindratio will have a significant impact on the amount of minerals vaporization whichindicate that the amount of minerals has a strong correlation with the combustiontemperature field. Simulation results ofa single-burner furnace, indicate that the keyof controlling the gasification of minerals, even though controlling the formation ofsubmicron particles of pulverized coal combustion is controlling the combustiontemperature.