Study On Economic Storage Schemes Of Large Heavy Crude Tanks

Temperature drop occurs when oil temperature is higher than the ambient by heat dissipation.In order to improve the fluidity,heating is needed to assure exportation.Oil depots consume large quantities of energy while reserving it.It is of great significance to study the economic storage scheme of heavy crude tanks to reduce energy consumption.Due to the low condensation point,heavy crude oil can be stored under pretty low temperature.No additional stress would be attached to the shell and roof of the tanks wihle heating the oil.Thus heavy crude can be stored without being heated except before exportation,which can reduce the heat exchange between oil and ambient significantly and is benificial for energy saving of oil depots.Based on the analysis of heat transfer process between the oil and the environment,a physical-mathematical model for temperature field calculation of large floating roof tanks is established,and a numerical computational software based on the SIMPLE algorithm is developed.The process of temperature depression of actual tanks is simulated with the software,the diviations between the calculated results and the measured ones are lower than 1.2 centigrades,which claims the reliability of the software.The software FLUENT is used to study the process of heat oil circulation process,the differences between the simulated and measured results are lower than 0.6 centigrade.Impact of initial temperature,oil level and wind velocity is studied in this paper.Higher initial temperature causes larger temperature differences between the oil and the ambient,so the temperature drop rate becomes higher as a result.Energy loss per unit mass in unit time decreases with the increase of oil level.Oil temperature drop rates under different wind velocities are almost the same,which implies wind velocity has little impact on the temperature drop rate.Oil temperature variations with two different storage schemes are simulated and the corresponding fuel oil consumptions are calculated.With the scheme of maintaining the oil temperature above a certain level,the fuel oil consumptions in winter,spring and summer are 595.6t,315.3t and 211.2t,respectively.When the heavy crude is stored without being heated except before exportation,the corresponding results are 372 t,191.6t and 91.5t,which are largely reduced by 223.6t,123.7t and 119.7t,respectively.With the latter storage scheme,the heating-up time in each month is 124.3h?72.3h and 36.5h,repectively.