Study On Heat Transfer Process Simulation And Emergency Protection Of Typical Chemical Storage Tank Under High Radiation Heat Flow Condition

The storage tank area has seen frequent fires in recent years.Due to the large size and dense arrangement of storage tanks,when a fire occurs in the storage tank,it usually has a high thermal radiation impact on other adjacent storage tanks,and the consequences of the accident are often relatively serious.Thermal transfer studies in the tank region consist of two main approaches:experiments and numerical simulations.The experiment has high risk,but the numerical simulation technology is mature and the results are reliable.Simulating the heat transfer in the tank area using numerical simulation software not only reduces the harm caused by the experiment and obtains the characteristics of the heat transfer in the tank area,but also obtains measures to reduce the consequences of the accident in the tank area through the emergency protection simulation.In this paper,we select a fire incident in a storage tank area to conduct a heat transfer simulation study.Through the investigation of the accident,the 120 m×75 m×15 m storage tank area model is determined,the model is established and the grid is divided.Realizable k-εturbulence model,DO radiation model and non-premixed combustion component transport model are selected for this simulation.The boundary conditions are set up according to the weather conditions when the accident occurs and are calculated iteratively until convergence.The heat transfer characteristics of fire in tank area and the influence of wind speed,wind direction and tank material on heat transfer are analyzed.Meanwhile,water spraying,emergency insulation coating and fire embankment were applied to the tank area fire incident to explore the effectiveness of the emergency measures.The main research results are as follows:(1)Heat transfer simulation of tank fire accident.Accident simulations show that the most affected tanks are the 6#-14#tanks that are directly eroded by the heat flow,with a maximum temperature of 1432 K,and a maximum combustion temperature of 2060 K at the southern exit.Other tanks in the tank area were mainly affected by thermal radiation,and the temperature was all below 870 K.The tight arrangement of the tank area causes the gas velocity to increase when it flows from the wider channel to the middle area of the narrow two tanks,and the flow velocity appears to be greater than the inlet velocity.The tank failure time(TTF)is calculated and the TTF is about 790 s.(2)Effect of wind speed on heat transfer in tank area.Five wind speeds of 5.3m/s,7.9 m/s,10.7 m/s,13.8 m/s,and 17.1 m/s were simulated.The flame inclination Angle is positively correlated with the wind speed,and the flame extension distance also increases with the increase of flame inclination Angle,which leads to the tank wall being closer to the flame and the temperature being higher,but also reduces the influence range of the accident.When the wind speed was 17.1 m/s,the maximum wall temperature of the tank increased by 124 K compared with the accident temperature of 5.3 m/s.(3)Effect of wind direction on heat transfer in tank area.Five wind directions were simulated:east wind,19°north east wind,45°north east wind,71°north east wind and north wind.The 45°wind from east to north has the most serious effect on tank wall temperature,and almost the whole tank wall temperature increases.The east wind mainly affected 2#-5#tanks.Because these tanks contained more material,the impact was just as severe.The east by North 19°wind or east by North71°wind has a limited range of effects on the tank farm,mainly affecting the west or east side tank wall temperature increase,but tanks 13 and 14#located in the middle area are affected in both winds.North winds had the least effect on tank farms,mainly affecting 6#-10#tanks.(4)Effect of tank material on heat transfer in tank area.As the thermal conductivity of the material decreases,the maximum temperature in the tank area also decreases,and the relationship between the two is approximately proportional.The affected area remains basically the same as 6#-14#tanks.(5)Study on the influence of water curtain emergency protection on heat transfer in tank area.When the water spraying intensity is 2 L/min·m~2,the maximum temperature in the tank farm decreases about 55 K.When the water spraying intensity increased to 6 L/min·m~2,the maximum temperature of the tank farm dropped about 653 K,and most of the tank temperature was below 620 K,and the cooling effect was obvious.(6)Study on the effect of PPMHI-L expanded emergency thermal insulation coating on heat transfer in storage tank area.The simulation results showed that the maximum temperature in the tank farm was 671 K,which was 761 K lower than the simulation results without the emergency heat insulation coating,and the tanks were all in a safe state.(7)Study on the influence of fire breakwater on heat transfer in tank area.The function of the fire break was primarily to block the flames,isolate the fuel for a short period of time,and slow the heating rate of the south tank.The maximum temperature of the 6#-14#tanks,which are more affected,is reduced by 529 K.The temperature of the 2#-5#tanks on the north side was increased by the backflow of some of the burning gas due to the fire break.