Abstract
Liquefied natural gas (LNG) leaks often lead to cascading accident disasters, including vapor cloud release, explosion, fire, and toxic gas release. The origin and evolution of each accidental disaster must be considered when assessing safety. This paper discusses the safety assessment project of an LNG gas storage station in Xuzhou, China. Multiple conceivable disasters due to the leakage of LNG storage tanks are simulated and analyzed using the computational fluid dynamic software FLACS. We studied different wind speeds interacting with the flammable vapor cloud area and creating frostbite in areas of low temperature. Diffusion simulations of vapor cloud explosion (VCE), thermal radiation, and the distribution of toxic substances were performed. The overpressure-impulse criterion was used to calculate the influence range of VCE. Heat flux, heat dose, and heat flux-heat dose criteria were used to calculate the safe distance for personnel in the event of fire. Based on the calculation results of the three latter criteria, this paper recommends using the heat flux criterion to evaluate fire accidents. The danger zone of each accident was compared. VCE accidents yielded the largest area.
Highlights
Liquefied natural gas (LNG) is an efficient, clean, and relatively inexpensive energy source and widely used in every daily life, industrial production, and other fields [1]
Parameter Determination. e LNG storage tank volume was 157.9 m3, the initial inside pressure 0.6 MPa, and the LNG temperature was −162°C. e atmospheric pressure was assumed as 1.01 × 105 Pa, the atmospheric temperature was set to 20°C, and the wind speed was 0 m/s, 4 m/s, and 8 m/s, respectively. is allowed the discussion of the influence of wind speed on the gas diffusion. e relative turbulence intensity was 0.1, and the turbulence length scale was 0.01 m. e leakage hole diameter of LNG storage tank was 100 mm, and the leakage hole was assumed circular. e leak rate was calculated using the leak module of FLACS with an initial leak rate of 38.25 kg/s
LNG leakage and diffusion were simulated under three wind conditions with a wind speed of 0 m/s, 4 m/s, and 8 m/s
Summary
Liquefied natural gas (LNG) is an efficient, clean, and relatively inexpensive energy source and widely used in every daily life, industrial production, and other fields [1]. E diffusion and explosion models and the combustion fireball from LNG leakage are studied by many researchers. Is method uses computational fluid dynamics (CFD) software FLACS simulation of LNG leakage on a series of disasters and considers the evolving scenario, namely, from a liquid pool after LNG evaporation followed by combustion, explosion, and yielding combustion products. Lv et al [12] established a reduced model of 160,000 m3 LNG storage tank according to the ratio of 1 : 100, carried out LNG explosion tests, and simulated the explosion process with FLACS. Ren [14] studied the changing law of temperature in the process of large-area LNG leakage and explosion using numerical methods. Is original process above introduced the progression of LNG leakage accidents, with some deficiencies yet Four of these deficiencies were improved in this study. (4) We evaluated fire accidents from three aspects of heat flux, heat measurement, and their comprehensive influences, respectively, and compare the calculation results of the three and found out the most optimal evaluation index
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