Research On Key Technology For Metal-seated High-temperature Wear-resistant Ball Valve

Organic silicon material has excellent integrated performance and has been applied in numerous fields of production and living. Organic silicon industry is a field of our country for energetic development. The medium of material return system for the organic silicon monomer production device is a medium of high-temperature gas-solid two-phase flow with its solid phase as the silicon powder, the medium of gas-solid two-phase flow has very strong abrasion on the ball valve on the delivery pipeline and its high-temperature abrasion characteristics require that ball valve not only resists wear, but also can adapt to high-temperature environment, but existing ball valve cannot satisfy the requirements, it is required to research the key technology of high-temperature wear-resistant ball valve with a view to developing the high-temperature wear-resistant ball valve for material return system of organic silicon monomer production device so as to satisfy the demand of the development of organic silicon industry in our country on high-temperature wear-resistant ball valve. Under the sponsorship of the technical key problem tackling program of Department of Science and Technology of Zhejiang Province—"development of ceramic wear-resistant ball valve" (program No. 2004C31006), a deeper research is carried out on the key technology for metal-seated high-temperature wear-resistant ball valve with respect to the medium characteristics of material return system for organic silicon device in this paper, mainly including the following contents:(1) Characteristics of sealing surface of ball by double glow plasma diffusing W and carburizing. Detailed experimental researches have been carried out on the penetration depth, phase composition of penetration layer, hardness distribution of the penetration layer of 2Cr13 subjected to double glow plasma diffusing tungsten alloying and carburizing hardening treatment as well as deformation amount of closure member—ball of 2Cr13 ball valve subjected to such hardening treatment and static pressure life of seating face of the ball, the experimental results show that the seating face of 2Cr13 ball subjected to double glow plasma diffusing tungsten alloying and carburizing hardening treatment has small processing amount, thick hardening layer, high hardness and long static pressure life, thus ascertains that the double glow plasma diffusing tungsten alloying and carburizing process is a hardening process that can make the seating face of 2Cr13 ball of metal-seated ball valve has excellent integrated performance.(2) Precision machining technology of seating face of ball of metal-seated ball valve. Two structural models have been proposed for the lapping equipment with two rotary shafts for seating face of ball, and the principle of lapping and forming of seating face of ball realized based on these two structural models have been analyzed; in order to improve the lapping quality of seating face of ball, the relation between the rotational speeds of the two shafts of the lapping equipment for seating face of ball has been analyzed and the relation between them has been determined; the calculation formula for lapping speed of lapping ball has been derived ; the integral structural style of the lapping equipment for seating face of ball and structural style of components have been proposed; the effect of process parameter values on lapping effect of seating face has been analyzed and process parameter values for lapping of seating face of ball have been given based on this. Test has been conducted on the lapping effect of prototype of the lapping equipment with two rotary shafts for seating face of ball, and the test results show that the lapping equipment with two rotary shafts for seating face of ball can lap out a seating face of ball of metal-seated ball valve whose sealing performance achieves zero leakage, thus verifies the structural feasibility of the lapping equipment with two rotary shafts for seating face of ball and reasonability of values of lapping process parameters.(3) Structure of high-temperature anti-seizure metal-seated ball valve. A new type of structure of high-temperature anti-seizure metal-seated ball valve - structure of high-temperature floating centering metal-seated ball valve with preset eccentric ball is proposed, and the operating principle of this structure of ball valve is analyzed.(4) Sealing structure of high-temperature metal-seated wear-resistant ball valve. A double-side sealing structure that can seal the seat before and after a type of metal-seated high-temperature wear-resistant ball valve is proposed; calculation formula for specific sealing pressure of seating face of valve seat is derived based on the analysis of stress condition of the double-side metal-seated high-temperature wear-resistant ball valve seat; criteria for determining width of valve seating face is proposed with respect to the features of double-side sealing structure and based on this methods for determining the width of valve seating face is given; a structure of combined packing seal of conical flexible graphite rings for valve stem is proposed, and operating principle and features of the sealing structure of this valve stem is analyzed.(5) Wear-resistant lining technology for internal chamber of metal-seated high-temperature wear-resistant ball valve body. Hot spray coating process type of wear-resistant coating for the internal chamber of valve body is given and coating material is determined based on the analysis of wear type of internal chamber of valve body.(6) Experimental research on metal-seated high-temperature wear-resistant ball valve. Pressure test and operating condition test under high-temperature abrasion condition have been carried out on the prototype of the metal-seated high-temperature wear-resistant ball valve, the test results show that the metal-seated high-temperature wear-resistant ball valve has excellent sealing performance, flexible operation under high-temperature abrasion condition and long service life, and verify the structural reasonability of high-temperature floating centering metal-seated ball valve with preset eccentric ball and valve seal as well as wear resistance of the wear-resistance coating determined.