The Effect of Spring Stiffness on Dynamic Characteristics of Interconnected Pilot Valves in the Steam Valve Set

The steam valve set (SVS) is the key protection device for nuclear power plants, including steam isolation valve, steam safety valve, interconnected pilot valve (IPV) and so on. The dynamic characteristics of IPV are directly related to the security of SVS under overpressure conditions. The effect of spring stiffness on dynamic characteristics of IPV and the fluid force of the IPV disc during the opening process are analyzed. The research results show that increasing the spring stiffness causes the change of valve disc movement from stable-state to unstable-state and then to stable-state. The response time of reaching the maximum opening gradually decreases with the decrease of spring stiffness under the stable-state. The decrease of spring stiffness causes the increase of velocity of valve disc and the decrease of fluid force of valve disc under the stable-state. The results of this article can provide reference for the research of similar pilot valves.