Abstract:

To improve the emergency management of the fire prevention and emergency response of the liquified natural gas (LNG) receiving station, and to clarify the essential mechanism and environmental effect of high expansion foam suppression on leakage and diffusion of cryogenic liquid, an experimental study of high expansion foam suppression on leakage and diffusion of liquid nitrogen through an indoor foam generator and wind tunnel device was conducted by control variable method. Then, the drainage behavior and suppression effect of high expansion foam on cryogenic liquid under different conditions between crosswinds and thermal radiations were also measured. The results show that at the initial stage, the drainage rate of foam is fast. The drainage rate of foam gradually decreases with the decrease of liquid quality in foam system, and the drainage rate of foam decreases exponentially. With the application of crosswinds and thermal radiations, the foam drainage rate rapidly increases. There are different stages of rapid increase, stable stage and rapid decline stage during the dynamic process of the evaporation rate for foam application on liquid nitrogen. The evaporation rate in stable stage shows a linear increase trend with a maximum value of the evaporation rate at 43.5% and 69.9% when the wind speeds increase from 0 to 3.5 m/s and thermal radiations increase from 0 to 350 W/m², resulting in a decrease effect of high expansion foam.

Key words: expansion foam, cryogenic liquid, crosswinds, thermal radiation, drainage rate, evaporation rate