Study On Full Surface Fire Calculation Model And Risk Zone Of Large Tank

With the rapid development of China's petrochemical industry and constructions of oil reserves,the safety of large oil depots and large tanks is of increasingly importance.However,in recent years,large-scale-tank-fire accidents have occurred frequently at home and abroad,which has serious impact on energy reserves,personnel health and property safety.The reason for this is that it lacks of research on the serious fire scene,the low standard of fire safety and the poor targeting of fire-fighting facilities.Based on these backgrounds,this paper studies the impact of thermal radiation on the full surface fire of large storage tanks,and there are several conclusions as following:(1)The tank fire accident cases are summarized in terms of large storage tank fire hazard and combustion mechanism,which shows that the large tank fire accident increases recently,and the highest frequency of fire storage medium is oil,and outside of floating roof tank stands for a large proportion.Finally the sealing ring is the most common fire scene,and the most serious consequence is the full surface fire.(2)The calculation models of the full surface fire of large tank are studied and optimized.By comparing with the experimental results of Tomakomai crude oil fire experiment and these of multiple models,the suitable research model is presented to analyze the full surface fire of large storage tank.Using the Babrauskas formula to calculate the burning velocity,the Heskestad equation and the Thomas formula are used to calculate the flame height without wind and wind.The Mudan model is used to calculate the flutter angle.In addition,the FDS software is used to simulate the fire scene so as to seek the parameters such as the intensity distribution of the radiation and the flame temperature.(3)The proposed model is utilized to simulate the full surface fire of the large tank under the variable wind speed.Combustion characteristics,plume morphology and temperature,heat release rate and thermal radiation are studied with different wind speed at 0m/s,4m/s,8m/s and 12m/s respectively.It is concluded that the wind speed is proportional to the flutter angle of the flame and is inversely proportional to the height of the flame.At the height of the tank,the thermal radiation intensity of the downwind direction is exponentially decaying with the distance.At a height of people,the thermal radiation intensity firstly increases with the distance farther away,reaches the peak at 20~30m and then drops down slowly.(4)The personnel safety distance and the safety risk area of adjacent tank are studied in terms of thermal radiation damage.The non-acceptance risk area of the adjacent tank under four wind speeds are 35 m,40m,53 m,48m under the low wind direction.The critical safety distance of the unprotected personnel is 178 m,181m,184 m and 180 m,and the critical safety distance of officers and soldiers is 45 m,48m,60 m,62m respectively.Based on the evaluation of the fire spacing of the tank in the full surface fire scenario,it is suggested that the tank spacing can be maintained by 0.52 D.