液氢用低温三偏心蝶阀的反向密封性能分析

Analysis of deformation of tri-eccentric butterfly valve and its influence on sealing performance

针对液氢用低温三偏心蝶阀较难现实反向密封的问题,对三偏心蝶阀在实现反向密封过程中出现的泄漏问题进行分析,探讨了三偏心蝶阀密封的影响因素,研究了三偏心蝶阀反向密封时蝶板的变形。结果表明:在流体反向流动时,解决蝶阀密封副的密封比压,是解决液氢用低温蝶阀反向密封的关键;三偏心蝶阀密封副的密封比压与其过盈配合设计相关;三偏心蝶阀密封圈的密封面边线是形成接触密封的关键位置,将过渡区的面密封改为线密封,有利于降低三偏心蝶阀在关闭时密封圈对阀座的磨损程度,为确保蝶阀形成有效的反向密封,蝶阀关闭时须在密封面上形成连续的密封比压;通过对蝶板和阀座结构采取加大密封部件的刚度和提高密封副的结合程度等优化设计措施,可实现三偏心蝶阀的反向承压密封的功能。选取Class150 NPS42三偏心蝶阀,使用氦气测试其在液氮(-196℃)环境下的反向密封性能,通过试验验证,低温蝶阀在设计压差内的泄漏量不能超过4 L/min,满足并优于标准允许的泄漏值,研究结果可为液氢用低温三偏心蝶阀的设计提供参考依据。

In response to the difficulty of implementing reverse sealing in low-temperature tri-eccentric butterfly valves for liquid hydrogen,the leakage problem occurring during the process of reverse sealing in tri-eccentric butterfly valves was analyzed,the influencing factors of tri-eccentric butterfly valve sealing were explored,and the deformation of the butterfly plate during reverse sealing in tri-eccentric butterfly valves was studied.The results indicate that solving the sealing specific pressure of the butterfly valve sealing pair during reverse fluid flow is the key to solving the reverse sealing problem of low-temperature butterfly valves for liquid hydrogen;The sealing specific pressure of the tri-eccentric butterfly valve sealing pair is related to its interference fit design;The edge line of the sealing surface of the tri-eccentric butterfly valve sealing ring is the key position to form contact sealing;Changing the surface seal of the transition zone to a line seal is beneficial to reducing the wear of the sealing ring on the valve seat when the tri-eccentric butterfly valve is closing;To ensure effective reverse sealing of the butterfly valve,a continuous sealing specific pressure must be formed on the sealing surface when the butterfly valve is closing;If we want to let the tri-eccentric butterfly valve to achieve the function of reverse pressure sealing,it can be achieved by optimizing the design measures such as increasing the stiffness of the sealing components and improving the bonding degree of the sealing pairs,etc.on the butterfly plate and valve seat structure.Class150 NPS42 tri-eccentric butterfly valve was selected to test its reverse sealing performance in liquid nitrogen(-196℃)environment using helium gas.Through experimental verification,the leakage rate of the low-temperature butterfly valve within the design pressure difference cannot exceed 4 L/min,which satisfies the allowable leakage value of the standard.The research results can provide a reference basis for the design of low-temperature tri-eccentric butterfly valves for liquid hydrogen service.