| With the increase of petroleum storage and transportation and the expansion oftank farm, the evaporation loss and environmental risks caused by petroleum storageand transportation have become increasingly prominent. Therefore, analyzing the riskof tank farm and the related events in petroleum storage and transportation, andaccurately estimating the evaporation loss of the tanks have a great significance forformulating feasible measures against risks in tank farm and reducing petroleumevaporation loss.This paper analyzes the system’s risk of storage and transportation enterprisestank farm by fault tree analysis method which is based on the risk identification. Italso explores the factors influencing the evaporation loss of storage tank, measuresthe petroleum saturated vapor pressure which is the key influence parameter, andmeasures the evaporation loss of tank model, and thus derives a formula to estimatethe evaporation loss in tank. The accuracy of the calculation results are analyzed bycomparing the calculation results of foreign and domestic formulas for calculating theevaporation loss.From the identification of material risk and system risk during productionprocess of tank farm，we found the major risks of tank farm are fire and explosioncaused by fire source and the leak of oil and gas. The statistics and cause analysis ofUSA, European and domestic leakage accidents show that operational errors,equipment failures, third-party damage and corrosion are the main causes.We structure the tank farm fire and explosion accident as the top event of a faulttree and found that OR gate accounted for75%, and AND gate accounted for25%, sothe risk of the system is big. Minimum cutsets of the fault tree are975groups, whichshow a high probable of accident. The coefficients of structure importance for basicevents from big to small are that oil gas concentration reached the lower limit ofexplosion, various causes of poor ventilation, various reasons of oil and gas leakage,fire sources in different ways and so on, these basic events must become a priority indeveloping effective prevention projects. Analyzing the sorting of the basic event’sprobability importance and critical importance show that the priority for avoiding anaccident is to control of oil gas concentration under the lower limit of explosion, andthat reduce the respiration evaporation of petroleum in tanks is easy to operate,remarkable in controlling effects, and can effectively improve the security of the system.Through analyzing the causes of petroleum evaporation loss in storage andtransportation process and comparing foreign evaporation loss of storage tankestimation method with domestic, the results show that the dome-roof tanks have amore wastage in small breathing losses than floating-roof tanks. Considering the smallbreathing losses continue a long time and have complex influence factors so it isdifficult to calculate accurately. This study measures the saturated vapor pressure ofpetroleum and small breathing evaporation loss by simulating dome-roof tanks. Theresults show that the petroleum saturated vapor pressure varies with the change oftemperature have a same trend with the small breathing evaporation loss, so thepetroleum saturated vapor pressure is a key characteristic parameter to the smallbreathing evaporation loss.On the basis of experiment research we derive the formula to estimate the smallbreathing evaporation loss of dome-roof tanks, and use it to calculate the evaporationloss of the experiment. The estimation results is bigger than the experiment results,the average relative error is about4.70%. Comparing the estimation results of ourformula with the API theory formula and Konstantinov formula, we find the formuladerived has a highest estimation accuracy, and the second is the Konstantinov formula.The estimation accuracy of our derived formula increased about3.14%thanKonstantinov formula, and the estimation accuracy of API theory is the worst. |
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