The Impact Of High-sulfur Fuel Application On Predecomposition System And Its Treatment Technology Research

With the reduction of high-quality resource day by day, low-quality fuel will gradually be utilized in cement industry. Confined by production technological levelof present cement, the range of coal adapted is relatively narrower. The New Dry Process cement enterprises in our country generally use low sulfur soft coal. But thereserve of high sulfur coal resources in our country is quite abundant. Therefore, if high sulfur coal could be utilized in cement industry, it can not only contribute to abate the complexion of scrambling for resources with other industries and boosting up the international competitiveness of our cement technology, but also is of great significance to our cement industry to realize the development goals of saving energy, reducing consumption, and clean production.The main problem of the high-sulfur coal used in the new type dry-process cement production is that cycle enrichment of volatile constituent (including sulfur, chlorine and alkali) will easily lead to crust blockage on kiln back-end, precalciner and suspension preheater, which may cause serious influence on production. At present, domestic and overseas commonly used by-pass technology to solve this problem. But there is no in-depth study of by-pass system.In this paper, CFD technology was adopted to simulate the precalciner and by-pass device, and based on the simulation results, optimized geometric structure of precalciner and by-pass device. Main contents and research results in this dissertation are described as the following:(1) Did a in-depth study on process, mechanism and type of predecomposition system buildups, which can provide a theoretical basis on calciner’s optimization and buildups’generation.(2) Considering raw meal particle decomposition, the flow field is simulated by k-ε two equation turbulence models.Movement of raw material and coal particle is simulated by the particle stochastic trajectory model. Species transport method is adopted to simulate the combustion process inside calciner by developing the method of deducing the molecular formula of coal volatile matters based on the proximate analysis of coal and ultimate analysis of coal. The simulation results of calciner show that the coupled flow field achieves reasonable flow field distribution and combustion condition, which can avoid buildups caused by high-sulfur coal combustion.(3) By analyzing the strengths and weaknesses of two kinds shock chilling mixer now used, the author has designed a new cyclone shock chilling mixer which has a more applicable cooling effect and more extensive usefulness.(4) Considering calciner and by-pass device as a whole system, based on the results of numerical simulation, analyze the impact of the bypass device on the the calciner flow field and temperature field.(5) By comparing the combustion conditions in the calciner of both pulverized coal and heavy oil, the author find the combustion characteristic of the two fuels are quite different, and must appropriately adjust the structure and the corresponding parameters to adapt to the combustion of heavy oil.