The Application Of Pinch Technology Research In The Tail Gas Recovery Unit Of The Polysilicon Production Process

Polysilicon is the raw materials of solar cell production. In recent years, the production of polycrystalline silicon got rapid development with the continuous development of solar energy. The production processes of polysilicon mainly include improved Siemens method, Silane method, and metallurgical method, etc. By contrast, in our country, the main production processed of polysilicon is the improved Siemens method. The improved Siemens method is more mature production technology than the others, but the core technology is still in the hands of overseas developed countries, especially the technology of tail gas recovery process. Usually, the tail gas recovery process is very high energy consumption and costly of equipment maintenance. Therefore it is great significance to reduce the energy consumption of the tail gas recovery process in polysilicon production.In this paper, we studied the tail gas recovery process of polysilicon production by Aspen Plus simulates system. Compared with the results of actual production, Aspen Plus simulation calculation results are accurate, and these results can be used as initial value in process of energy saving research. The feed stage of the tower and the effects of feed temperature to reboiler load were also analyzed by Aspen Plus sensitivity analysis system. The optimal feed stage of desorption column is30, and the higher the feed temperature the better.The domestic and international development situation, basic design philosophy and the application of pinch technology were also discussed in detail in this paper. The utilization of energy resources in the tail gas recycling process of polysilicon production was also analyzed using pinch technology, including10kinds of streams,13temperatures ranges. Furthermore the original/modified heat exchange network diagrams were drawn. Combined with the actual running situation of equipment, the energy bottleneck of tail gas recovery unit was found by the pinch analysis. The tail gas recovery unit of polysilicon production can save19.5%energy consumption of heating utilities and12.3%energy consumption of cooling utilities in theory. Accordingly, the heat exchanger E3and E9A are added, and the desorber inlet temperature was increased to60℃in the technological feasibility reform.