Key Equipment And Pipeline Stress Analysis Of LNG Gasification Station

China's urban gas is supplied by the natural gas pipeline network and LNG gasification station,they solve the problem of city gas peak shaving and emergency.LNG gasification station is usually built in the town.LNG is-162? low temperature liquid,it is flammable and diffuse.The equipments or pipelines which storage and transport LNG failure will cause LNG leakage,resulting in fire,explosion and other accidents,endangering the personal safety of staff.Therefore,in order to reduce the safety hidden trouble of LNG gasification station after operation,this paper analysed stress of the main equipment and pipeline in LNG gasification station,the following work has been carried out:(1)Researched.on the direct compression process and field pipeline stress of LNG gasification station,including the main equipment and pipeline,the load and stress of pipeline and its mechanical model.The characteristics of main equipment and pipeline stress analysis of LNG gasification station is analyzed.The LNG gas station pipeline stress and compressor nozzle calibration standards is determined.(2)According to the actual situation of the station site to determine the LNG tank outlet pipe constraints and boundary conditions,the use of CAESAR ? software to establish a pipeline model,and checked the flanges in the pipeline,optimized the pipeline to prevent the flange leakage.The stress and displacement distribution characteristics of the pipeline under installation and test of pipeline pressure,pre cooling operation,general conditions is studied,and determined the conditions should be focused on checking and the stress of the dangerous section.Analyzed the influence of the type of compensator,the position and size of the compensator,the density of LNG,the pressure of pipeline and the low temperature stress on pipeline stress.(3)Studied the characteristics of BOG compressor pipeline system and the cause of vibration.Started from the pressure fluctuation caused by the fluid in the pipe,calculate the pressure pulsation and unbalanced excitation force based on the plane wave theory,and compiled the pressure pulsation and exciting force auxiliary calculation program.And established the numerical model of the BOG compressor pipeline system,through static analysis to analyze the distribution characteristics of the stress and displacement of the compressor inlet pipeline,compressor outlet pipeline,suction pipeline and exhaust pipeline,concluded the pipeline needed to be focused and check the compressor nozzle force.(4)The harmonic analysis and modal analysis of the BOG compressor pipeline system were carried out to study the effect of the pressure fluctuation and the natural frequency of the piping system on the compressor pipeline system stress.Compared with a single compressor and dual compressor running's pipeline stress distribution,and studied the effects of the support spacing,the settlement of the foundation,the pressure of the pipe,the angle of the bend tube on the pressure and the pressure fluctuation on pipeline stress.(5)Puted forward the measures for reducing the pipeline stress of the main equipments and pipelines in LNG gasification station,including adding constraints,setting up the spring hanger and the cold tight unit,adding the expansion joint and the buffer.Proposed the concept of stress variation coefficient as a parameter to measure the effect of stress reduction.At present,there are few researches on the analysis of main equipments and pipelines stress in LNG gasification station at home and abroad.The research methods,the understandings and conclusions of this paper can provide a reference for the fine and detailed design of LNG gasification station pipelines.The influence of pressure pulsation on the compressor pipeline system and the auxiliary calculation program can also be used in stress analysis of other stations which have BOG compressor.