Numerical Simulation Of The Tiny-oil Ignition Burner In The Coal Boiler

Oil is very indigent in our country, and oil price is higher and higher in the international market. But it needs to consume a lot of oil during the course of pulverized coal boiler commissioning, cold startup, stop and low load combustion stabilization. Therefore, the realization of the boiler less oil and oil-free ignition technology that it is important significance to save oil. The tiny-oil ignition burner is a specially designed burner. It can ignite a lot of coal with a small amount of oil, and it can achieve the purpose of ignition and stable low load combustion stabilization of the coal boiler. It is a commonly uesd to fire the spray with the high-energy ignition oil-gun, and then ignite dense phase pulverized coal with the high-temperature oil flame. Finally, combustion of dense phase coal ignite the dilute coal. By this way carry the energy getting larger and larger. Tiny-oil ignition technology has characteristics of low investment, the structure of simple equipment, simple maintenance and good effect of oil-saving. Now it has been widely used to a number of the large-scale coal boiler, and it is very important significance to reduce the cost of power generation, save oil resource and enhance the energy security for china.Firstly, this paper introduces constitutes of tiny-oil ignition burner system, the basic characteristics of burner, and the ignition principle of the various parts of the burner. And the paper summaries up the tiny-oil ignition technology and economic characteristics. Then, this paper simply introduces the CFD software FLUENT, and account of the ignition process of the basic conservation equation. K-εmodel is employed to simulate gas turbulent flow. Equilibrium Mixture Fraction/PDF Model is employed to simulated gas turbulent combustion. P-1 model is used to simulate radiation heat transfer. Two competing rates model is employed to simulate pulverized coal volatilization. Stochastic tracking model is employed to simulate pulverized coal track. Kinetics/diffusion limited model is employed to simulate coke combustion. Secondly, the ignition and combustion process of small oil-gun is simulated with the right equations and mathematical models. By analysis of its temperature and velocity field, the result shows that the temperature at center of combustion chamber spout is highest and temperature fall gradually from center to brim,which presents parabola. Velocity distribution is like as temperature. Distribution of temperature and velocity is described with equations which are used as the boundary condition of tiny-oil ignition burner numerical simulation. Oil combustion is simulated in different condition. The thesis gains the effect of swirl intensity and spray angle on temperature of oil combustion chamber. Thirdly, according to the tiny-oil burner of the structural characteristics, this paper is numerical simulation of two different structure of burner. Key ignition factors distributions such as the temperature field, velocity field, CO₂ distribution, CO distribution, O₂ distribution are obtained, wihich studies the ignition characteristics of tiny-oil ignition burner in the round. Finally, ignition and combustion process of tiny-oil ignition burner is simulated with CFD software FLUENT in different condition. The thesis gains the effect of primary air velocity, pulverized coal concentration, and oil-gun layout angular on the ignition characteristics of tiny-oil ignition burner, and summaries up the ting-oil ignition technology features.The result can be used to supply gist with ameliorating and designing tiny-oil ignition burner.