Research on the Unsteady Discharge Flow of Dry Chemical Powder Tank
Abstract
In this study, we investigated the activation of powders by the supply of N2 gas in the dry chemical powder tanks. In this study, we investigated the effect of N2 gas on the activation of dry chemical powder (KHCO3) in Dry chemical Powder Tank, We studied how dry chemical powder (KHCO3) is activated according to the number of nozzles in the tank. 170 kg, and 3000 kg models, the number of nozzles was 4, 8. We gave the points to confirm the activation of the powder. This study describes the optimal conditions for activation depending on the type of dry chemical powder tank and the number of nozzles.
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Introduction
According to the "Marine Accident Statistics" at the Maritime Tribunal, the number of ship fires and explosions in the Republic of Korea is 465 cases (2011 ~ 2015) for 5 years, accounting for about 6% of all marine casualties. Among them, the oil tanker fire and explosion accident accounted for 8% of the total of 256 cases [1]. Generally, half of ship fire accidents are reported to occur in the engine room. In case of an accident, it is difficult to receive support for fire suppression from the land, and therefore, many lives and property are lost [2].
The Powder fire extinguishing system is a fire extinguishing system that suppresses fire which is less effective by water extinguishing method such as sprinkling water or scattered water and combustible gas or oil with the risk of fire spreading. The powder fire extinguishing system is a device that injects N2 gas filled in N2 cylinder into powder tank, push powder fire extinguishing agent into N2 gas pressure in powder tank and spray fire extinguishing agent in fire area. The principle of extinguishing the powder absorbs heat from the fire by the rapid endothermic reaction of the powder which is released in the place where the fire occurs. As the volume of the non-combustible powder expands, the powder covers the fire and blocks the supply of oxygen, thereby suppressing the fire.
The powder fire extinguishing system is suitable for the extinguishing of large-scale flammable gas fires and is suitable for the fire extinguishing of liquefied natural gas carrier (LNGC), liquefied petroleum gas carrier (LPGC), liquefied natural gas - floating production storage facility (FLNG) ), Drillships, and gas and marine plant facilities. Powder in Dry Powder Tank mixed well with N2 gas in case of fire suppression needs to be maintained after optimal activation.
In this study, we have investigated the activation of powders in accordance with the supply of N2 gas in the dry powder tank and studied how the powder is activated according to the number of nozzles in the dry powder tank.
Conclusion
In this study, we investigated the activation of powders in dry powder tanks. The effect of the number of nozzles and pressure on the powder is summarized as follows. It was confirmed that when the nitrogen gas was pressurized in the 3000kg-Dry powder tank for 20 seconds, the dispersion of powder was uniform. In the 3000kg-Dry powder tank, when the number of nozzles is 8, the dispersion of powder is better. In the case of 170kg model, it was confirmed that there is a pressure to activate the powder according to the number of nozzles. When the number of nozzles was 4 and 8, it was activated well at 17.7 bar and 16.7 bar. It was defined that the state of activation depends on the shape of powder tank of 170kg and 3000kg. Therefore, the more the shape of the tank is closer to the ellipse, the better the activation is.