Cryogenic extinguishment of liquid pool fires

Abstract

Results on fire extinguishment using direct application of liquid nitrogen are presented in this article. This technique targets challenging fires, such as burning hazardous chemicals or fuels, in which cases prompt suppression or extinguishment is paramount to prevent explosions, avoid release of toxic fumes and avert environmental catastrophes. Liquid nitrogen is a rather environmentally benign extinguishing agent that does not cause property damage or groundwater contamination. Application of this cryogen onto a hot pyrolyzing/burning surface induces abrupt vaporization, spread and expansion. The pyrolyzing gases are inerted, the surface is cooled and hence its pyrolysis rate is reduced, air is separated from the fuel, and the fire extinguishes. To demonstrate this technique, experiments were conducted with pool fires of ethanol, propanol, and diesel fuel. To examine the underlying principles, analysis of the results was conducted based on simplified calculations. Sufficient quantities of the cryogen extinguished the fires nearly instantaneously. Half-liter quantities were sufficient to extinguish 1 m 2 pool fires. The method of dispensing and distributing the cryogen on the pool fires proved to be of considerable importance. The existence of wind, which disturbed the flame, was not found to prevent extinguishment.

Study of fire–extinguishing efficiency of environmentally friendly binary aerosol-nitrogen mixtures

“…According to the research results of the same authors [23], only a mixture of 1-bromo-3,3,3-tryftorpropen with nitrogen possessed high fire suppression efficiency through the synergy of its components. In order to obtain "environmentally" friendly fire suppression agents, the researchers suggest using liquefied nitrogen [24,25] which, as they point out, can be used to extinguish fires in the buildings and the reservoirs. But the question arises as to the technological implementation of this method, which of course will be more expensive than standard storage of compressed nitrogen in cylinders.…”

Pool fire extinction by remotely controlled application of liquid nitrogen

“…With the flow rate of 0.0142 L/s and a time of 7 s per pan, the amount of LN 2 used per unit area of pool fire was ∼1.06 L/m 2 for these tests. This is double the amount reported by Levendis and Delichatsios [1–4], but it is possible that a smaller amount would have extinguished the fires. Based on the results and efficacy of this small‐scale model testing, the feasibility of the concept in full‐scale is recommended.…”

“…LN 2 flow rates may be in the order of 1 L/s, based on past large scale tests by the FAA [12, 13] with chemical extinguishers. Whereas the mode of fire extinction of LN 2 is not the same as that of those chemical extinguishers, the required flow rates are not too different, based on our previous work [1] where manually delivered cryogen at 0.25 L/s extinguished a 1 m 2 fire in seconds.…”

“…This study was conducted to assess practical methods of delivery of liquid nitrogen (LN 2 ) to fires. In previous research [1–4], direct application of liquid nitrogen was shown to effectively extinguish pool fires of various fuels, such as ethanol, isopropanol, and diesel oil. It was determined that cryogen quantities of one liter were sufficient to extinguish one square meter liquid pool fires.…”

Experimental Investigation on the Cooling and Inerting Effects of Liquid Nitrogen Injected into a Confined Space

“…Besides, LN 2 is also an environmentally benign and highly efficient extinguishing agent and applied in fire prevention and extinguishing due to the remarkable cooling and inerting effect [5][6][7]. The major fire extinguishing mechanisms with LN 2 include: (1) refrigeration and cooling because of the very low temperature of the cryogen and the latent and sensible heat; (2) inerting of the atmosphere-the vaporization expansion times of LN 2 is high in that 1 L LN 2 can vaporize to 647 L gaseous nitrogen in the standard state [8].…”