Study On The Sealing Performance Of Large Reduction Furnace

Reduction furnace is an important equipment for polysilicon production.Its production conditions are very bad.During normal operation,the furnace temperature is as high as 1100 ℃,and the reaction medium contains hydrogen,which requires high purity and airtight.It belongs to the national class III pressure vessel,and class III is the highest risk vessel in the national compulsory verification equipment.In case of leakage during the operation of reduction furnace,the risk of flash explosion and fire will occur.Therefore,it is of great significance to ensure the sealing of reduction furnace for safe operation.This project mainly carries out the research and design on the sealing performance of large-scale reduction furnace(40 pairs of rods).Through the research and design of gasket material,flange bolt connection loading mode and load distribution,equipment flange structure and other aspects,the method to solve the sealing problem is explored.The research mainly includes the following aspects:Based on the research and design object of 40 pairs of rod reduction furnace,the PTFE material is selected as the sealing gasket of reduction furnace by comparing the physical properties of the gaskets of different materials,such as tension,compression rebound and creep relaxation.The thickness and width of PTFE gasket are selected and designed through calculation.The preload of 40 pairs of rod reduction furnace was studied,and the load distribution of bolts was studied.The size and number of bolts needed were designed.At the same time,the loading mode of bolts was selected.The study mainly made the load between bolts meet the sealing requirements and evenly distributed,and it was also easy to operate in the production process.By changing the flange structure of the reduction furnace,the cooling system of the chassis of the reduction furnace is created.The commonly used Bach method,Timoshenko method and waters method are compared to find a method suitable for designing the flange size.Finally,the reduction furnace chassis flange is simplified into a flat cover model.The equivalent thickness is calculated by the equal moment of inertia theory.The strength check is carried out by using SW6,and the thickness of the flange is finally determined.The designed flange structure is simulated by finite element method.According to the finite element calculation results,the stress load of the sealing part of the reduction furnace chassis is analyzed.From the connection displacement nephogram,it is found that the displacement of the flange joint is small enough to lead to the leakage of the seal.From the equivalent stress diagram,the stress is concentrated in the inner wall of the flange jacket,and the influence on the whole flange is relatively small.The flange strength is enough to meet the working condition,and the bolt connection also keeps good contact The above analysis shows that the seal design of the reduction furnace is reasonable and reliable.