Mechanism Analysis And Experimental Research Of Pulverized Coal Charging And A Computer Simulation

Based on the consideration of high efficient combustion and low pollutant emission of pulverized coal, a new method of corona charging combustion is proposed. While among of it, the charging for pulverized coal is a foundation and key step. Referenced lots of documents of domestic and overseas, we founed that there is few research about the pulverized coal charging. Therefore, a depth and comprehensive study on mechanism and characteristics of pulverized coal charging is very necessary.This thesis mainly consists of three parts: mechanism analysis of pulverized coal charging, experimental research of charging regularity and trajectory simulation about charging particles of a pulverized coal.Firstly, through analysis and comparison of all kinds of charging methods, the corona charging method is prior selected to carry out the pulverized coal charging. Deriving from the theory analysis of general particle corona charging and the characteristics of pulverized coal, obtained the charging formula of pulverized coal's particle in the mechanism of electrical charge. According to the formula, the major influencing factors and their tendency were determined.Secondly, a line–cylinder charging apparatus and measuring system of electrical charge were set up. The charge to mass ratio is used as charging evaluation index, which was measured at different pole positive voltage,mean sieving particle size,jet flow velocity, powder feed concentration and coal types, obtained the single factor experimental regularity of pulverized coal's corona charging. On the basis, through deleting the secondary factors and ignoring the interaction between factors, a three factors and three levels orthogonal test was carried out, which contained the powder feed concentration, pole positive voltage and mean sieving particle size. Then, on the basis of variance analysis of a large amount of the experimental data, gained the optimal charging condition about the three factors. Ultimately, using the multi-variable non-linear regression analysis, obtained the charging regression equation of pulverized coal with the orthogonal testing data. Through verification, the reliability and efficiency of the equation had been affirmed. It can be used as the prediction equation for the experimental research.Finally, according to the force operating on a charged particle, built a mathematical model for the particle's trajectory in the line–cylinder charging apparatus. The model involved in particle charging equation, electric field and charge conservation equation, gas conservation equations of mass and momentum, particle mass and momentum equation. Loading electrostatic field force into the model by the compiled UDF ( User-Defined Function ) and using the discrete phase model of the FLUENT software for simulation, showed the trajectory regularity about a charging particle of pulverized coal on different pole positive voltage,mean sieving particle size and jet flow velocity .