Study on Technique of Controlling Pipeline Surge Increasing Rate

Control of pipeline surge increasing rate can play such a role as avoiding early over pressure occurance, reducing the frequency of usage of the pressure protection system allocated at stations, reducing vibration to the piping, and preventing the low voltage instruments and equipment from being damaged. Summarized in the article are the control method and device adopted in foreign designs, such as pressure relief valve system, air pressure buffer system, electronic/hydrolic relief system, rubber sleave relief valve system and fly wheel system, etc. The principle and structure of the new type relief valves of dual functions are described emphasizely. Through the study on mathematic and physical models of pressure increase regulation system guided by the control theory of surge pressure increase, the writer discovered the nonlinear nature of the regulation under fixed friction, it requires a large energy accumulation system. Friction should be changable and self-compensable to reduce the capacity of energy accumulator. The new type of dual functions relief valves can overcome the shortcomings of the first generation of dual functions with rubber valve plug, which are easy to get aging and deform due to futigue and poor in low temperature resistance. Metal valve plugs are adopted with careful and skillful treatments of the reflexibility of actions, tightness of closing, and the initia of movement, etc. Reasonable compromise should also be performed between the necessary prefastening of springs and the start up pressure of valves, between stiffness and operating course. A year operation of the new type pressure relief valves of dual functions proves that this kind of valves can effectively avoid damages caused by surge so that safety operation is able to be guaranteed.