Research On Function Safety Design Optimization And Internal Leakage Detection Of Safety Valve

Safety valve is one of the main facilities to ensure the safety of pressure devices and equipment such as boilers,pressure vessels and pressure pipes.It is regarded as the final pressure relief device of production system,also known as the last line of defense for production system safety.In case of overpressure,it is very important to correctly perform the relief function of safety valve.In order to ensure the correct function of the safety valve,researchers have been improving and optimizing the safety valve.At the end of 1980 s,Europe put forward the concept of functional safety,which aims to control,avoid and reduce the occurrence of risks,and ensure the safety of people,property and environment.Later,it put forward the basic standard IEC61508 of functional safety.In2006,China put forward the functional safety standard GB / T20438,which introduced the concept of functional safety into China.The concept of functional safety is generally used in electrical electronic and programmable electronic safety related systems,which also has guiding significance for the design of pure mechanical products,such as safety valve.Based on the concept of functional safety,this paper optimizes the design of safety valve.The goal is to improve the safety integrity level of safety valve and ensure that its safety relief function can be more stable.In this paper,the concept of functional safety of safety valve is established,the calculation method of safety integrity level of safety valve is explored,and the FMEDA analysis method is used to explore the impact of each part of safety valve on safety integrity level.Combined with the above research,the optimization direction of functional safety design of safety valve is put forward: reliability improvement of safety valve body and on-line monitoring system for internal leakage of safety valve according to the main failure mode of safety valve.The research on internal leakage detection of safety valve is the focus of this paper.Based on the reliability improvement of safety valve body,this paper analyzes the failure mode of safety valve and FMEA,and determines the failure mode of each link.According to the pyramid model,the reliability of each unit of safety valve and the reliability of the system are evaluated,and finally the research idea of safety valve reliability improvement is put forward.Based on the failure of internal leakage of safety valve,this paper proposes the research direction of on-line monitoring system of internal leakage of safety valve,mainly studies theprinciple of internal leakage detection of safety valve.According to the principle of acoustic emission detection,the frequency characteristics of acoustic emission signal and the influencing factors of acoustic emission signal(inlet pressure,leakage size,leakage number,etc.)are studied.According to the formula of leakage rate in safety valve fitted by predecessors,a new fitting formula is proposed,and the validity of the formula is analyzed through experiments.At the same time,based on the principle of Hartmann sounder,the resonant cavity structure is designed,which improves the sensitivity of internal leakage detection of safety valve,improves the detection accuracy,and can detect small leakage.Finally,the interference problem of the same pipeline is explored.