Research On Heat Transfer Law Of Tubular Heating Process Of Crude Oil Storage Tank

At present,China has built eight oil reserves,but there is still a huge gap between China's crude oil reserves and the 90 day safety standard of the international energy administration.With the further implementation of China's oil storage project,the safe and economic storage of crude oil has always been a hot issue in the oil and gas storage and transportation industry.When the temperature of crude oil in the tank is low,the poor fluidity of crude oil will lead to huge economic losses and even serious production accidents.Tubular heating is widely used in engineering to heat the crude oil in the tank to maintain the temperature of crude oil.The research on the heat transfer law of tubular heating process in the tank has guiding significance for the formulation of scientific and economic process plan.In order to guide the practical engineering problems more directly and make the research more close to the complex practical engineering problems,this paper uses the method of combining experiment and three-dimensional numerical simulation to study the heat transfer law of crude oil tank tubular heating process,including the following research contents:Firstly,the visualization of flow field is realized based on particle image velocimetry(PIV),and the temperature measurement is realized based on thermocouple temperature measurement technology.The experimental system and method for simulating the tubular heating process of storage tank are constructed.The characteristics of velocity distribution and its evolution,the characteristics of temperature distribution and its evolution,and the effects of different tube heating parameters on the experimental medium flow and heat transfer were obtained.According to the velocity distribution characteristics of the medium in the experimental tank,the flow field in the tank can be divided into three regions: low velocity flow region,longitudinal convection region and transverse flow region.The longitudinal convection zone and the transverse flow zone form a vortex which is mainly affected by natural convection.The temperature in the center of the experimental tank shows a trend of up high and down low.The heating temperature has a great influence on the local velocity of the flow field.The flow rate of heating tube has a great influence on the swept area of natural convection.Secondly,considering the heat transfer process between the media inside and outside the heating tube and the coupling characteristics of multi physical fields in the heating process of crude oil storage tank driven by various thermal boundary conditions,a three-dimensional mathematical model and its solution method are established to characterize the flow and heat transfer behavior of crude oil tubular heating process.The numerical simulation results of the simplified annular heating tube show that there is an obvious high temperature plume above the heating tube,and the natural convection of crude oil in the tank is obvious.The numerical simulation results of the serpentine heating tube show that the plumes generated by the heating tubes at different positions affect each other,and the optimal heating effect of the serpentine heating tube is located above the geometric center of the coil.Finally,the influence of different process parameters and structural parameters on the heat transfer characteristics of oil tank tube heating process is analyzed.The results show that when the flow rate of serpentine heating medium decreases to 1 / 3 of the original,the temperature gradient along the flow direction in the heating tube increases by 2.72 times.When the inlet temperature of the heating tube decreases,the plume height above the heating tube decreases.When the simplified annular heating pipe is changed from horizontal arrangement to vertical arrangement,the natural convection characteristics in the tank are more obvious.When the installation height of the heating tube increases,the average heat flux of the heating tube decreases.When the diameter of the simplified annular heating tube is doubled,the average heat flux of the heating tube increases by25%,the variance of crude oil temperature increases,and the average rate of crude oil temperature increases.