Study On Pressure Change Of Natural Gas Pipeline And Parameter Setting Of Gas-liquid Inter-stage Valve

Pipeline transportation has been gradually widely used in petrochemical industry.Because it bears the transportation task for special materials such as flammable and high pressure.Therefore,when abnormal working conditions occur in the process of pipeline transportation,reasonable methods used for restraining the danger has become the direction of exploration for the development of pipeline transportation industry today.At present,most natural gas pipelines are inspected on site by manual line patrol,but this method has some limitations.The gas-liquid inter-stage valve can ensure that the gas pipeline shuts down automatically when the pipeline breaks and leaks.Its principle is that the pressure drop rate detected by the gas-liquid inter-stage valve exceeds the normal range set by the parameters,the emergency shutdown operation is adopted.Since the gas-liquid inter-stage valve,the core control device of valve chamber of natural gas long-distance transmission pipeline,is often set with empirical values in the process of pipeline transportation,the result will cause the parameter setting to be too high,the leakage cannot be detected and the parameter setting to be too low.Changes in working condition caused by thunder,peak shaving and other reasons will also cause that the function of emergency shutdown function is started.Therefore,based on the specific working conditions and aiming at the problem of pipe breakage and leakage of natural gas pipelines,several typical horizontal pipelines is studied and analyzed in this paper.The main research idea is to describe the laws of natural gas flow in the pipeline and pipe breakage and leakage based on the gas dynamics theory.On this basis,a simulation model is established by using the transient oil and gas analysis software Pipeline Studio to study the influence of different operating conditions on the pressure drop rate of the starting valve chamber and to explore the influence of pipe breakage and leakage on the pressure drop rate change of the upstream starting valve chamber.The simulation results are fitted by the fitting software Design Expert,and the relationships between different pipe diameters,leakage aperture,pressure,pipe throughput and maximum pressure drop rate are analyzed,thus a set of gas-liquid inter-stage valve parameter setting method is constructed.Finally,based on the theoretical results,a gas pipe break leakage experiment is designed.The data measured by the experiment is based on the mathematical software Matlab.“sym8 wavelet” is selected for wavelet de-noising analysis.The de-noised pressure signal is subjected to data processing and parameter setting methods for comparative verification.The difference between the experimental results and the theoretical results is explored.Through comparative analysis of the experimental values and fitting values,it is found that the accuracy is more than 88%.Therefore,the parameter setting method of gasliquid inter-stage valve has certain reliability and can provide certain reference basis for field engineering application.