| This thesis is intended to make a study for the sealing characteristics of spring-loadedsafety valve. The force balance equation and deformation compatibility condition under thebalance condition of safety valve are established, the critical factors affecting the sealing ofspring-loaded safety valve are given, and the design to improve the sealing of spring-loadedsafety valve is put forward through the analysis of working principle of spring-loaded safetyvalve to realize the sealing and the sealing force of each seals. The thesis puts forward themethod of adoption of balance device including external balance device and internal balancedevice to compensate the sealing force for safety valve before its upcoming opening to avoidthe simmer problem by solving the problem of small sealing force as a breakthrough throughthe establishment for balance mechanism theory of sealing force of safety valve as a stepfunction of system pressure and experimental study from the perspective of improving thesealing force directly. Moreover, several advanced structure to improve the sealing ofspring-loaded safety valve are proposed on the basis of valve design and experiences ofapplication from perspective of improving sealing force indirectly, including: adopt thethermo-disc structure to improve the decrease of sealing force for valve before upcomingopening to prevent the simmer problem better; improve the properties of spring to guaranteethe sealing force during the operation of safety valve, especially in high-temperaturecondition; adopt double-exhaust structure to reduce the impact on the sealing surface duringthe discharge of safety valve in order to improve sealing force. The research on externalbalance spring direct acting safety valve has been applied in practice. |
