Process And Equipment Optimization Of The Polysilicon Reduction System

Polysilicon reduction furnace（CVD）is one of the most important equipment of the polysilicon production process.Optimizing the operation of the process and upgrading the equipment both contribute to the reduction of the energy consumption and the enhancement of quality and quantity of the single furnace output.Operating parameters of the polysilicon furnace are studied and analyzed in this thesis.With the changing of feeding method,reducing the ration of the mixture of H₂and SiHCL₃,improving the operating pressure of the polysilicon reduction furnace,decreasingthetemperatureofthefeed-stock,theaimof energy-saving and cost-reducing is achieved.The thesisbrings forward that operating pressure of the polysilicon furnace should be 0.5MPa,reaction temperature is controlled at 950¹050℃,the ratio of H₂ and SiHCL₃ at the first 10 hours is 4:1,and from 10 hours to 80 hours is 2.5:1,for the rest of time the ratio is 3.0-3.2;3%-5%of DCS is added.Adjustment of these parameters can greatly reduce the cost of polysilicon production,improve product quality.Without changing the size of the chassis of the reduction furnace,the polysilicon rod is added to 30 pairs.The position of the outlet and nozzle of the inlet is simulated by simulation software.For each model,the flow field,thermal field,temperature field and distribution of concentration of components are compared and analyzed.Air inlet quantity should be increased to 24,four ring configuration,from the outer to the inner ring is respectively:9+6+6+3 layouts.The three nozzles in the center areΦ10¹2,the rest of the nozzles areΦ10 x 12,Φ11 x 9.The outlet arranged in the periphery of the chassis,threeΦ100 outlets are distributed in the outer ring evenly by 120°.The polysilicon reduction process is optimized and the equipment is much more stabilized,so that the production cost is reduced.At present,power consumption of the 30-rod reduction furnace is reduced to 48kW·h/kg-Si,which is at least 20%lower than the power consumption of the traditional 24-rod polysilicon reduction furnace.