Numerical Simulation Study On Heat Transfer Characteristics Of Floating Roof Tanks During Static Storage And Heating Process

With the development of China's petroleum reserve project,the problems of accurate measurement and safe storage of floating roof tanks have aroused a wide concern in the society.In this paper,it carried out a numerical simulation to model the static storage and heating process of floating roof tanks,as well as an in-depth study of the influence of various factors on the temperature field and heating of crude oil,which could be of great reference value for oil measurement and oil storage safety.The specific research contents are as follows:(1)Under the influence of environmental changes which are dominated by solar radiation,it studied the change rules of temperatures of crude oil and wall in the floating roof tank while building a three-dimensional model of the floating roof tank.Besides,an unsteady numerical simulation was conducted by solar radiation model to obtain the change rules of temperatures of crude oil and tank wall within a day in summer: It is shown that under the influence of environmental changes which are dominated by solar radiation,high temperature oil layers with large temperature gradient occur near the tank wall and the floating roof,the thickness is 0.2 m and 0.8m respectively,and there is less influence on the temperature of deep crude oil;a proposal that using different tank wall temperature calculation formulas under different conditions with consideration of the solar radiation is offered.(2)In order to study the effect of rotational speed and jet velocity of rotary jet mixers on the heating of crude oil,a three-dimensional model of floating-roof tank was established to simulate the heating process of crude oil at different rotational speeds and jet velocities of rotary jet mixers based on the analysis of heat exchange process of floating-roof tank during heating.From the numerical simulation,it is shown that in the process of crude oil heating and with the help of mixing by rotary jet mixers,the rate of temperature increase in crude oil in the floating-roof tank is significantly higher than that without mixing condition,the rate of temperature increase in crude oil gradually rises with the increase of rotational speed and jet velocity of rotary jet mixers.But when the rotational speed is too high,the rate of temperature increase in crude oil decreases instead,when the jet velocity is too high or too low,the rate of increase in the temperature rise of crude oil has decreased.mixing conditions can improve the temperature unevenness caused by the heating of crude oil.(3)In order to study the effect of rotational speed and jet velocity of rotary jet mixers and oil sludge thickness on the heating process of steam coil when heating crude oil,numerical simulation was performed to analyze the three-dimensional model of floating roof tank by the use of multiphase flow model.Finally,the distribution situations of crude oil and oil sludge,temperature,and flow field during the heating and mixing processes were obtained.The conclusions are as indicated here below: oil sludge has exerted a significant impact on the heating of crude oil.The temperature rise rate of crude oil is greatly reduced compared to the conditions without oil sludge.For crude oil containing sludge,the increasing rate of the temperature of crude oil is relatively higher when the rotary jet mixer is at low rotational speed and high jet velocity.It is shown that if the oil sludge is thicker,the heating and stirring efficiency of the crude oil would be lower and the time for even mixing would be longer.