대용량 탱크 이중 물분무 설비 효용성에 대한 고찰

Abstract

본 연구는 대용량 저장 탱크(위험물 저장 탱크 높이 15m) 관련 기준과 실제 사고 현장을 조사하고 최악의 상황을 고려한 시뮬레이션을 통해 대용량 저장 탱크에서 화재가 발생하는 현상을 규명하여 실제 피해 위험에 따라 소방 설비가 적합하게 설치되어 있는지에 대해 고찰하였다. 이를 통해 법규의 효용성 및 설치 효과를 분석함으로써, 국내 관련 법규에 대한 개정의 필요성을 확인하고, 실제 소방 설계시 효율성을 제고하기 위해서 본 연구 를 수행하였다.

There are many various international and domestic fire protection standards, codes, regulations applied in the refinery and petrochemical plant, Korea Fire Act regulated the tank which is over 15m height shall be double water spray ring. So when calculation of demand of fire water for plant, generally the maximum demand of water requirement would be massive jumbo tank fire. Let me define the massive jumbo tank is the atmosphere tank which has over 15m height in this paper. Korean Fire Act which is about installation of double water spray in the massive jumbo tank is not appropriate with the past incident histories, other international code & standard and simulation results. Therefore, the fire protection engineer in the plant should consider more cost efficient design compare to real performance. So this paper describes about the last incident histories, international and Korean standards, codes, regulations, the related engineering theories and the result of simulations which are used in the worldwide. To improve the reliability of simulation, the worst condition should be reflected according to codes and various references. The fire tank which is located in the one of refinery is the biggest one in Korea. Therefore there is no controversial about simulation results. This paper present 3 aspects as follow. 1)Incident Histories and Related International Codes and Standards In case of incident histories, there is not much serious thermal radiation damage on the tank shell under tank top pool fire. Because of the heat transfer on the liquid in the tank inside, the shell side of under pool fire, it is very difficult to get thermal damage. But the shell side over pool fire is opposite case. The flame can make the over shell side easily damage. So, ground level and around low elevation area is not much affected by tank top pool fire. That's why most of exposed tanks which are located around the fire tank have good condition painting on the tank shell. The good condition painting means no thermal radiation effect. All of international codes and standards describe that too much usage of water spray are obstacle of fire activity. Because it makes causes in shortage of water supply and foam fire fighting. So fixed water spray should be selective facility not obligation. If we have choice, we have to use alternative fire fighting facilities for example, fire truck and portable hoses. As a result, these codes and standards are not complied with Korean Fire Act. 2)Consequence Analyzing by Simulation Software TRACE 9.1(SAFER), PHAST 6.53(DNV) are simulated as tank top fire and pool fire. These two simulation software is not exactly same calculation method. But the basic modeling is TNO pool fire. But depends on company, there are many various constants and some of Know-How. So the result is not well gone with each other. The maximum simulation result is 20kW/m2 which is well matched according to the thermal radiation theories on this paper. This thermal radiation makes not the shell of tank damaged. So both of fire tank and exposed tanks are not easily damaged by pool fire on the tank top. It means the tank top pool fire doesn't much need the double water spray. This paper does not deny the necessity of single water spray. Before mentioned, the water spray should be selective choice. So there are so many conditions such as distance and risk. The engineer who is charged with this design should hazard evaluation of this area and facilities and determine the water spray design scheme. 3)The Calculation for Demand of Water Spray In case of calculation by Korean Fire Act, the demand of water spray is the 3.6 times than real demand of water spray. This calculation is based on the water converted into steam. If the double water spray ring is installed in the tank, the demand of water spray is estimated as 7.2 times. So the amount of overused water is 6.2 times than real demand of water spray. As a result of this paper, the Korean Fire Act about double water spray is not appropriated in the view of engineering and risk based point. So this regulation should be recheck and revision for efficient engineering fire protection design.