Field experimental study of high expansion foam coverage after LNG leakage

Abstract

With the rapid development of the world’s natural gas industry, LNG (Liquefied Natural Gas) has received widespread attention as a clean energy source. However, the leakage accidents of LNG are usually accompanied by safety hazards such as explosions, low temperatures, and phase transitions. In this study, the field experiment is carried out to cover LNG leakage pool with HEF (High-Expansion Foam). In the process of LNG leakage, when the ambient temperature at the bottom of the reservoir drops to about − 82.3 °C (the critical temperature of LNG), the ambient temperature would rise briefly due to the effect of phase transition. Meanwhile, the temperature distribution of different vertical and horizontal positions in the reservoir during the process of leakage is analyzed. Besides, it is also found that the density of the spilled vapor is much lower than that of the air, but the water in the surrounding air encounters the cryogenic vapor to condense into small droplets, the small droplets entrap part of the flammable gas during the process of settling to the ground, therefore, the flammable vapor still shows a heavy gas effect. During the initial period of HEF coverage, evaporation from the liquid pools accelerates, resulting in a 386% increase in peak concentration of methane above the reservoir. Nevertheless, when HEF application is maintained an effective thickness, it can effectively reduce the methane vapor concentration downstream of the reservoir near the surface to less than 1/2 LFL (1/2 of the Lower Flammability Limit). In general, the large-scale field experiments have far-reaching engineering significance and reference value for the occurrence and emergency treatment of LNG leakage accidents under actual working conditions.