Numerical Simulation Algorithm Of The Thermal Flow Field In A Kiln Inlet Predecomposition System And Its Engineering Application

and research results in this dissertation are decribed as the following:(1) 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.(2) Based on the previous research works all over the world, the decomposition model of raw meal particle suspained in calciner is studied and developed. The chemical kinetic parameters test method of raw meal decomposition is developed by using high temperature furnace, electronic balance and stopwatch as main test instruments according to the practical condition on the spot, overcoming the difficulty that thermal gravity analysis (TGA) blance is not equipped at production line labouratory.(3) Based on multiphase flow program hierarchy of CFD commercial software(Fluent6.3) and the numerical analytical model of raw meal decomposition, multiphase species transport method is adopted to further develop the numerical solution programe of raw meal decomposition, which realizes the coupled flow field study of coal combustion - raw meal decomposition inside calciner. A good consistency is achieved by comparing simulation data with engineering test data from production line.(4) The boundary condition algorithm of cyclone ash outlet is achieved by deep analysising the practical gas-solid flow processes happen in cyclone ash outlet and ash discharge pipe, and then the dust collection efficiency numerical solution programe is developed with the help of multiphase flow program hierarchy of Fluent. "Euler-Euler" method is adopted to simulate the gas-solid multiphase flow inside cyclone, and the study of cyclone dust collection efficiency that is based on the practical gas-solid flow processes in ash outlet is simultaneously realized for the first time, which is convincingly proved by test data.(5) On the basis of finishing the studies of cyclone gas-solid two phase flow and dust collection efficiency, the study of cyclone heat exchanging efficiency is realized that is based on the thorough multiphase flow inside cyclone and rigorous heat balance principle, which lays the important theoretical foundation for establishing the research method of preheater heat exchanging efficiency. (6) According to the technics process of preheater system, the solution algorithm of gas-solid two phase flow field inside preheater is developed, and then the study of gas-solid two phase flow field inside preheater is realized for the first time all over the world. On the basis of the study of preheater gas-solid two phase flow field, the research method of preheater heat exchanging efficiency is developed that is based on the thorough gas-solid flow process inside preheater. This kind of preheater heat exchanging efficiency research method thoroughly breaks away from the disadvantages that use C1 outlet temperature to approximately evaluate the heat exchanging efficiency of preheater in engineering, and also overcomes the restriction that is difficult to calculate the heat exchanging efficiency due to the indetermination of prheater heat loss to the outside, therefore it can not only calculate the heat exchanging efficiency of the same preheater at different woking conditions, but also can do those of preheaters with different series, size, and type. As a result, this research method of preheater heat exchanging efficiency can not only guide the industry production practice of preheater, optimizing some operation parameters, but also can be directly used to aid the preheater's development and design work.(7) Aiming at CBMI general contract project of Larfage Yong Chuan 5000t/d production line, firstly, by using the research method of calciner flow field in this dissertation, the numerical simulation is carried out for the calciner initially designed for this production line, and then some corresponding optimization schemes are put forward for the unreasonable flow characters from the simulation results; secondly, based on the optimized shceme, the coupled flow field is simulated again for the optimized calciner and achieves more reasonable flow field distribution, which provides important theoretical guide for the design work of the calciner in this production line.