Research On The Temperature Drop And Vibration Law Of Gas Regulator And Its Safety Reliability

Gas Regulator of RMG530 is the critical pressure regulating device in gas distribution stations.Hydrate dissolve out and clog the regulator in high pressure and low temperature environment which caused by throttle effect as gas flows through regulator.The impact of the ice against the valve body cause violent vibration in gas regulator of RMG530,the violent vibration caused by throttle effect as gas flows through regulator is liable to cause fatigue failure of valve body.Aimed these questions above,the distribution and throttling process model of RMG530 was established based on the analysis platform of element analysis software FLUENT,simulated the variation of internal fluid velocity,pressure and temperature under different working conditions,analyzed the effect of inlet pressure,pressure drop and environmental temperature on the temperature drop caused by throttle effect as gas flows through value.Cast steel 1.6220 at hot rolled and quenched and tempered state is chosen as the research object to analyze the mechanical properties at low temperatures(room temperature--80?)by using low temperature tensile tests and series impact tests.Ductile-brittle transition temperature is calculated;electron microscope scanning and macro image of cross section at different temperature are observed.Applying loads according to the actual working condition,considering the effect of cable heating on temperature drop and thermal stress,the flow field analysis of natural gas,the static and stress field analysis were carried out.The structure stress and deformation in the process of running condition was got through simulating the start-stop process of the pressure reducing valve under winter and summer working conditions based on the analysis of the fluid inside the valve.The effect of pulsating cyclic stress on valve fatigue damage was analyzed and the static fatigue life of pressure reducing valve was carried out by finite element fatigue analysis software NCode according to the correctional S-N curve of valve material;In order to assess the safety and reliability of the value body under random vibration loading,the stress response power spectral density is obtained by flow control valve vibration response analysis based on field test of random vibration load.According to the modified S-N curve of the reducing valve material and with the application of finite element fatigue analysis software Ncode,random vibration fatigue of the reducing valve is analyzed by the method of time domain and frequency domain.It is shown that,the flow field in the throttle is extremely complex,and intense turbulent flow characteristics are presented.In the natural gas throttling process,the velocity explodes while stress and temperature plunge which provides the suitable condition for precipitation of the hydrocarbons.Dew point,gas flow temperature,inlet pressure and temperature drop are the main factors on the ice blockage problem at natural gas distribution station.Forecasting model of ice blockage and computational formula of methanol injection prove that results of judgement and prediction is in accordance with actual running status of gas distribution station.The yield strength and tensile strength of the steel elevate with the reducing temperature,while the reduction of area and elongation reduce;quenching and tempering significantly improve the material mechanical property,the ductile-brittle transition temperature of cast steel 1.6220 at quenched and tempered state is-14.46?,while the ductile-brittle transition temperature at hot rolled state is 2.76?.The value structure design is relatively conservative,the various response amplitudes are small so that the sympathetic vibration is not occurred in the use process.The minimum fatigue life point under random vibration loading is at the corner of the imports section to the valve seat with the minimum calculated fatigue life in time domain 41.79 years and the minimum calculated fatigue life in frequency domain 38.81 years.The research results provide a reference basia for safety and reliability assessments of valve body structures and the development of automatic control system at natural gas distribution stations.