Thermodynamic Optimization Analysis Of Industrial Silicon Production Process And Numerical Simulation Of Heat Transfer Process In Furnace

Due to the extensive use of industrial silicon as well as its high energy consumption during the smelting process, it is essential that the quality of industrial silicon be improved and energy consumption be lowered by way of studying its smelting technique. This thesis simulates the energy conservation during silicon production in three parts, in order to give guidance on how to conserve energy during the industrial silicon production.In the first part, a thermodynamic model of industrial silicon production based on the method of minimum gibbs free energy is set up by a thermodynamic calculation software. Firstly, SiC is added in the ingredient for the process of silicon smelting based on technology of carbothermic reduction, upon which the additive’s impact is studied. Secondly, the possibility of using different reducing agent instead of carbon is researched. In addition, we analyze how temperature and pressure affect the production of industrial silicon. As the simulation result shows, the amount of silicon generated increases dramatically and the reaction rate accelerates after adding SiC in the original ingredient, where temperature is lowered as well. The best ratio of the material is determined by analyzing the generation rate of industrial silicon with different ratio of the material. When carbon is replaced by CO, H2, CH4respectively as reducer, only CH4produces a little silicon. While studying the impact of temperature and pressure, we found that the productivity of silicon rises as the pressure increase and fall as the temperature goes up.In the second part, the dynamic model of a two-dimensional axisymmetric MHD dynamic model of plasma arc is solved by the software of finite element analysis in the first place. Moreover, the physical form and the heat-transform mechanism of electric arc is analyzed, which is focused on how different current and arc length affect the form of arc. When comparing the simulated result with the experimental data released, we verify the simulation method and result. In the meanwhile. the factors which influence the heat transfer efficiency from the arc to the anode are researched. As the simulated result shows, the longer the arc is, the less efficient the heat transfer on the anode of the bath surface is, on the condition of different current and arc length. According to the simulated result and the principle of industrial silicon smelting, it comes to the conclusion that the industrial silicon will be better produced in the mode of long arc, undercurrent and high voltage.In the last part, a3-D model of industrial silicon generating process is solved by the software of finite element analysis COMSOL4.3a. Factors including furnace pressure which is the simulated pressure result in the second part, metal height and permeability of the bottom dead material which have influences on silicon production are analyzed. And the result indicates that silicon generating speeds up as the given pressure increases. While heightened metal can as well accelerate silicon production, the effectiveness is too faint to be noticed; on the contrary, low permeability lowers the speed of silicon production. Hence, by comparison, the pressure plays a more important role than the heightened metal and the permeability of the bottom dead material in generating silicon.