Energy Conservation And Optimization Of Polycrystalline Silicon Production Process

With the release of producing capacity of many polysilicon enterprises in China,to decrease the production cost of polysilicon has become the first requirement for the survival and sustainable development of those companies.With the purpose of reducing the power consumption,decreasing the production cost and improving the comprehensive competitiveness,those companies should take measures to optimize the production process and technologies as well as enhance the utilization rate of the equipment.Under the research background of one unit of 15 thousand-ton equipment for polysilicon production,this paper has analyzed the production process.It is also found that the high level of power consumption and low utilization rate of the equipment is the bottleneck leading to the high production cost.After optimizing the process and technologies of the two key devices for hydrogen reduction of trichlorosilane and hydrogenation of silicon tetrachloride,this paper has put forward some measures for energy saving and system optimization.First of all,hydrogen reduction has been identified as the unit which consumes the most electricity during the production.According to the principle of the reduction,the experiment of adding SiH₂Cl₂ to the reducing furnace with the aim of reducing the power consumption has been carried out.By comparing the experiments with different proportions of SiH₂Cl₂,this paper has found that the addition of 3 percent of SiH₂Cl₂ in the reduction process can optimize the comprehensive economic benefits by reducing the power consumption of silicon rod by 5.11kW·h/kg-Si and creating the energy-saving benefit of 3.526 million RMB.Secondly,given the low utilization rate of reducing furnace,some optimization measures have been taken to reduce the operation time of reducing furnace and accelerate the operation of start-stop furnace.It has not only effectively improved the utilization efficiency of reducing furnace but also increased the operation times of reducing furnace.Based on the existing devices,it can increase the output ratio of the polysilicon by 4.17 percent.Lastly,considering that 18 fixed-bed hydrogenation units in a polysilicon company function with a low utilization rate,this paper has analyzed the efficiency of the single unit and also calculated the repair cycle of each device.Through the optimization of repair cycle,the utilization rate has been improved greatly with the processing capacity improved by 5.19 percent.