Numerical Study On The Temperature Field In Large-scale Floating Roof Oil Tank And The Development Of Simulation Software

Heat is passed between with the large-tanks and external environment in the process of oil storage.In winter,when the temperature of high viscosity crude oil is higher than the atmospheric temperature,the crude oil temperature in the tank will decrease.When the oil temperature drops to the wax precipitation point,the wax will begin to precipitate.Because of the decrease of oil temperature,oil fluidity decreases.When the amount of wax exceeds the critical value,the wax crystals will form the porous medium.In serious cases,even condensation accidents may occur.In addition,the reduced oil liquidity will bring serious safety risks,and the temperature maintenance measure will bring high operating costs.Because of the higher ambient temperature,the light crude oil temperature will rise in summer.The increase of oil breathing loss leads to waste of reserve resources and serious environmental pollution in tank farm.Therefore,it is of great significance to develop a simulation software to calculate the temperature field of the most large floating-roof tanks.To explore the evolution law and influencing factors of the oil temperature can help to make the scientific heat preservation plan and operation plan.Heat conduction,convection heat transfer and radiation heat transfer occur in the crude oil storage process.It also involves a variety of complex physical processes such as wax evolution and rheological transformation of crude oil.This paper established the physical and mathematical model,based on the consideration of atmospheric environment,air layer,steel plate layer,thermal insulation layer,soil layer,tank structure and coupled heat transfer.The standard k-? turbulence model is used to describe the turbulent flow process.The Darcy's law and the enthalpy porous medium model are used to describe the wax evolution phase transition.The power-law equation is used to describe the non-Newtonian fluid characteristics.And in this essay,the periodic influence of solar radiation included direct solar radiation and solar scattering.The equations is discretized by finite volume method.In order to solve the temperature field of oil tank,the solid area is regarded as a fluid with infinite viscosity.FORTRAN language write simulation kernel code and the VB 6.0 language is used to write man-machine interface code.Finally,combining the two parts to develop the temperature field simulation software of the large storage tank.Researching the rule of large floating-roof tank temperature field by using the Large Tank Temperature Field Simulation Software.The influences of tank diameter,single plate and double plate floating-roof,liquid level height,oil storage temperature,thermal conductivity of insulating layer,sludge accumulation at the bottom of tank on the temperature field are explored.Based on the analysis results,the economic evaluation on Zhongyuan oil,Nanyang oil,Shengli oil and Luning oil is conducted,from the perspective of heating and temperature maintenance.Finally,according to the actual operation of these four oil depots,the corresponding safe and economic storage scheme is formulated.The results of this essay can provide some technical support for the formulation of production plan,crude oil storage safety and energy conservation and emission reduction.