Simulation Of LNG Explosion Consequences In Confined Space And Design For New Blast Wall

With the adjustment of energy structure in our country,the proportion of LNG in production and living is increasing day by day.However,many LNG leakage and explosion accidents have also occurred,resulting in huge casualties and property losses.LNG leakage and explosion accident in LNG terminal and pressure regulating station with semi-confined space are researched in this paper.A new type of energy-absorbing blast wall is designed and smallscale blast wall explosion test is carried out.The performance of blast wall was studied through numerical simulation.The paper depend on the open task of Ministry of public security's Key Laboratory Program: Study on the key problems of urban LNG station leakage disposal and accident prevention-control technology and China University of Petroleum independent innovation research program: Study on the key problems of urban LNG station leakage disposal and accident prevention-control technology.Research contents are as follows:(1)Numerical Simulation of LNG leakage,diffusion and explosion in confined space.Select the LNG terminal wharf and pressure regulating station as the research object,the use of FLACS software to establish the finite element model to simulate the gas leaks and diffusion at different wind speeds,to obtain flammable vapor clouds and vapor cloud diffusion range.The effects of different vapor cloud concentration,different ignition levels and different degrees of congestion on the explosion consequences of LNG terminals were simulated and analyzed,explosion overpressure field and temperature field were obtained.Simulate the consequences of explosion at different vapor cloud concentrations at the pressure regulating station and compared with the explosion results at the LNG terminal to provide overpressure data for the design of blast walls.(2)Design energy-absorbing blast wall.According to the good energy-absorbing property of the metal thin-walled structure,a metal thin-walled blast wall with a sandwich structure as the main body is designed.Blast wall is divided into two parts of the panel and sandwich,sandwich part of the metal thin-walled structure,the upper and lower panels made of the same thickness of the metal plate.Blast wall design from the sandwich structure,sandwich cell body wall thickness,cell body bearing direction,explosion-proof wall material four aspects,for ANSYS finite element modeling to provide the model size and material parameters.(3)Blast wall explosion experiment in small scale confined space.Design and processing of regular quadrilateral sandwich and hexagonal sandwich explosion-proof wall specimens,the establishment of explosion over-pressure data acquisition system and explosion-proof wall stress data acquisition system to carry out small-scale explosion-proof wall explosion experiment.Explosion experiments using oil and gas as the gas explosion medium,the test chamber is a totally enclosed space,and the oil gas is ignited by spark ignition.The strain changes on the back of blast wall specimens under different blast shock waves were collected,and the stress changes on the back of the blast wall were finally obtained.The stress variation of two kinds of specimens under different overpressure were obtained.(4)Numerical simulation of energy-absorbing blast wall.ANSYS17.0 is used to establish a finite element model of explosion-proof wall,and carry out pre-treatment operation such as boundary condition setting and load application,then export the keyword files and finally submit the LS-DYNA to solve.Based on the experimental explosion overpressure peak to carry out simulation analysis of blast walls.The change of the back panel stress is compared with the result of the explosion experiment to verify the accuracy and reliability of the numerical simulation results.The dynamic response of blast walls with different sandwich structures,different cell body thicknesses and different material blast walls was simulated,and the deformation and stress distribution of blast walls were analyzed to prove that the blast walls of this kind have good explosion-proof performance.On the 0.1mm cell body thickness hexagonal sandwich explosion-proof wall carry out maximum load carrying capacity research,the result is that the blast wall can withstand 1.5Mpa overpressure.