Theoretical Model Amelioration And Load Determination Of Temperature Holding On Large Floating Roof Tank

This paper was financially supported by National Natural Science Foundation ofChina (No.51106020, No.51174042, No.51051002), PetroChina Innovation Foundation（2012D-5006-0610） and Youth Scholar Backbone Supporting Plan Project ofHeilongjiang General Colleges and Universities (1252G005).In the oil production run, because of temperature difference between crude oil andexternal environment, heat transfer occurs through tank top, wall and bottom. When tankoil temperature drops to a certain value, wax precipitation leads to solidification structure,floating roof tank wall bottom are surrounded by a certain thickness and strength ofcondensate reservoir. When tank recovers operations, oil condensate, particularly that onthe tank, brings a serious threat to the safety restart operation. To solve this problem, themain way is to take timely temperature holding on oil tank. Significantly longer storagetime make it difficult to design temperature holding system of large floating roof oil tank.Therefore, accurate knowledge of temperature drop variation during oil storage, a scientificchoice on temperature holding method according to it, and reasonable heat load canprovide optimized operation process design of large floating roof storage tanks and ensuresafety and economic operation. This paper according to the analysis of temperature dropcharacteristics of floating roof tanks, heat transfer coefficient are accurately calculatedwithin stepwise tentative calculation, especially when it goes on the double-disc floatingroof tanks, heat transfer theory is combined. Unsteady discretization equations and heattransfer equations of Tank boundary nodes are derived on the basis of heat transfercoefficient that was got above. Oil tank temperature variation are determined within theimpact of floating roof type, tank level, tank volume, ambient temperature, wind speed, etc.The total heating energy consumption equals to the sum of various regions. The totalheating load is analyzed under different physical parameters and external environmentalconditions. Taking steam coil and energy cycle into consideration, the total heatconsumption and heating media usage are calculated under the circumstances that the tankvolume are respectively50,000m3,100,000m3and150,000m3.