Design And Research Of Rotary Seal Valve

Polycrystalline silicon is an important raw material of modern photovoltaic industry and electronic industry.In recent years,it takes the clean energy industry as the primary one to develop in international.It also strongly promotes the Polycrystalline silicon industry at home.The synthesis of chemical hydrogen silicon is a vital step of producing polycrystalline silicon.Among the synthesis system,rotating feed valve is key equipment.It can be used to add the silicon powder to the synthetic furnace quantitatively.The medium of which includes ultrafine silicon powder,hydrogen,hydrogen chloride,cross-linked silicon,etc.Facing such situations like the abrasion of silicon powder,the erosion of hydrogen chloride,it is easy to cause material leakage and gas cross-dressing,which is a hidden trouble for production safety.However,rotating feed valve cannot work quite well in such a bad working condition.So,this thesis,taking the working condition of synthesis system of chemical hydrogen silicon into consideration,aims at studying it thoroughly from the perspective of sealing structure design and wear and corrosion resistant of rotating feed valve.It mainly includes the following aspects.(1)Study on integral design of rotary dynamic seal:The V type packing and discharging hole and the blowing device combining the dynamic seal structure can effectively prevent the silica fume into the bearing gap,reduce equipment loss,and effectively prevent the leakage of silica fume;The surface of the valve body adopts the composite structure design,increase the resistance to hydrogen embrittlement of ultra low carbon steel layer,supersonic rocket spraying WC-17%Co hard alloy wear-resisting layer,and surface grinding,ensure the compactness and wear resistance of the coating surface;The arc integral cemented carbide is used as sealing surface,and through lifting valve seat system,the problem of arc hard seal in small space is solved effectively;Rotating valve internal alarm device to increase,can reflect the working conditions of the valve.(2)Study on properties of hard sealing materials:The tensile strength of cemented carbide was measured by Brazil splitting test at 114.5MPa;Based on the real hard alloy metallurgical image,the finite element model is established by the image processing and threshold segmentation;The tensile test of the finite element model is carried out,and the tensile strength of cemented carbide is predicted to be 132MPa;The fracture mode of cemented carbide is spallation,and the crack.propagates along the boundary of irregular WC particles in the process of crack propagation.