Numerical Simulation Of Leakage Diffusion And Explosion Process Of Natural Gas Storage Tank

As a clean,explosion limit of 5-15%,also has certain corrosion resistance and toxicity,hazard is opposite bigger,the leakage phenomenon can occur in the process of storage and transportation,gas density is smaller than the air of the nature of the cause of the leak after spread extremely easily,when gas clouds in ignition source may occur after the fire,explosion and other serious consequences,Eventually resulting in huge casualties and economic losses.In view of this,a large number of scholars and experts have conducted research on natural gas leakage explosion.Based on the results of previous studies,this paper uses FLACS simulation to study the diffusion law of leakage gas and the law of combustion and explosion after leakage of spherical natural gas storage tank area under the influence of a variety of factors.The main achievements of this paper are as follows:In order to study the law of natural gas leakage and diffusion,based on a natural gas storage tank area,this paper uses FLACS software to conduct CFD modeling in the plant area,and then sets different wind speed,wind direction,leakage rate,leakage direction and leakage aperture.The influence of the above working conditions on the distribution of concentration and velocity of gas leakage and diffusion after reaching a stable state and the influence on the variation rule of equivalent gas cloud volume Q9 with time was studied.It was suggested that the layout of gas concentration detection and alarm should be placed directly above the potential release source.In accordance with the national standard within the scope of combustible gas detection alarm device as far as possible arranged at a high place,in order to improve detection sensitivity.At present,the maximum alarm lag time stipulated in relevant standards is relatively loose,so it is recommended to choose the detection and alarm device with sensitive response and short alarm lag time.In addition,this paper also studies the flame shape change rule,the damage range of overpressure and high temperature,the maximum overpressure and the pressure and temperature change rule of each monitoring point after the gas cloud explodes in ignition source with different volume and concentration.After the explosion of natural gas cloud at the beginning of the ignition source to form a fireball,then the flame quickly spread around,at the same time the flame rapidly spread to the sky,the formation of a "mushroom cloud" shape,then,the flame size gradually smaller,and eventually dissipated.The pressure XY section diagram spreads rapidly to all sides from the ignition position as the center.In the initial stage,the pressure at the core position is the highest,while the boundary layer pressure is low.Then,the pressure at the explosion center drops and a negative pressure area appears.The XY section diagram of temperature spreads rapidly around the ignition location,with high temperature in the core location and low temperature in the boundary layer.The boundary layer is a "sawtooth"distribution.The maximum area of the high temperature area of the explosion was close to the moment of the highest pressure in the explosion center.After the temperature cloud area reached the maximum,the fracture appeared at the middle point and finally dissipated gradually from both sides.With the increase of gas cloud concentration,the maximum explosion overpressure(P)after the gas cloud is ignited increases first and then decreases.The closer the equivalent ratio of ER is to 1,the fuller the reaction is and the strongest explosion is;while the farther the concentration is from 10%,the smaller the maximum explosion overpressure is.