Numerical Simulation Of Mixed Coal Combustion In A 700MW Tangentially Fired Boiler

Coal is the main fuel in china and takes a probability of 70.7% in all energy sources output in 2002. It is always burnt directly, and the contamination concerned with this process is one of the main contaminative sources destroying the environment.There are many aspects such as the design and manufacture of the boiler, the steady combustion of the accommodate sets, the scorification in the boiler, the control of contamination and so on that need to know the combustion, flow and temperature in the boiler. But only finite data can be got through the measurement of traditional experiment. These days, along with the fast development of computer and the theory of pulverized coal's combustion, numerical experiment, which can complement the shortcoming of the traditional means, becomes another crucial method to study the above casesThe tangentially fired boiler possesses a large part of the market all over the world. In China, about 80% of the direct current burners take tangentially fired combustion as their burning way. This paper focuses on the burning process of the MB-FRR boiler produced by Mitsubishi, and several conditions are simulated to provide instructive guidance for the optimum design and operation of the boiler.The combustion process in the boiler, about turbulent flow and chemical reaction, is very complex, which is concerned with three-dimensional turbulent flow, multiphase and multicomponent flows. Heat transfer includes convection, radiation and conduction, while chemical reaction includes gas combustion, char combustion and so on. The paper adopted non-premixed combustion model. The equations for the mixture fraction are used to simulate volatile's turbulent combustion, and the simulation of gas turbulent transport employs theκ-εturbulent model, then for the radiation P-1 model is used. Besides, it selects the SIMPLE difference methods of non-interleaving gridding for the gas flow field, and accordingly the resolution of the turbulent diffusion about solid particle chooses the stochastic tracking model. The simulation emphases of the particle reaction are the separateness of the volatile and the oxidation of the char, while the first one's simulation uses Kobayashi model, and the other one takes the kinetic/diffusion surface reaction rate model.The paper's stressing points are as follows: (1) It studies the pseudo diffusion of cold simulation through image processing, and a method for gridding evaluation is put...