Study On Dehydration Characteristics And Mechanism Of Crude Oil Emulsion Under The Combination Of Ultrasonic And Electric Field

With the continuous accumulation of the total amount of oil extraction and the development of different oil displacement technologies,the water content and the complexity of its components are increasing year by year,which makes it impossible to realize the separation of oil and water efficiently and stably.Ultrasonic technology has developed rapidly in the field of viscosity reduction and dehydration of crude oil because of its good cavitation effect and displacement effect in liquid medium,but the ultrasonic intensity is too large or the radiation time is too long cavitation effect will also lead to the secondary emulsification of crude oil,which limits the popularization and application of ultrasonic technology in the field of crude oil dehydration.In this paper,a series of ultrasonic effects produced by ultrasound in liquid phase are used to reasonably combine the electric field with the ultrasonic field to speed up the separation of oil and water.In order to study the dehydration effect of crude oil emulsion under the combined action of ultrasonic and electric field and to find out the dehydration characteristics and dehydration mechanism under the combined action of ultrasonic and electric field,a crude oil dehydration test platform was set up in the laboratory,and the influence of different factors on the dehydration effect was studied by dehydration experiment and numerical analysis.The results show that the electric field intensity,frequency and duty ratio of crude oil emulsion have direct influence on the dehydration effect and have the optimal value.The dehydration effect of ultrasonic and electric field is better than that of electric field alone.The rate has a direct relationship,so the selection of suitable dehydration parameters plays a key role in increasing the dehydration rate;the acoustic-electric field is more suitable fortreating crude oil emulsion with higher initial moisture content than the individual electric field;under the action of individual electric field,the dehydration rate is proportional to the temperature.Combined with the experimental results of dehydration and theoretical analysis,it can be obtained that the greater the electric field intensity of water droplets under the action of electric field,the higher the deformation of water droplets,the more prone to polarization coalescence,but too high field strength will cause electric dispersion;the optimal electric field frequency is related to the radius of water droplets,the natural vibration frequency of water droplets,and the resistance to water droplets during their motion.In the early stage of dehydration,the number of water droplets is large and the frequency of water droplets is high.In the later stage of dehydration,the radius of water droplets is small and the frequency of water droplets is low.The displacement effect caused by ultrasonic mechanical vibration causes the water droplets to move towards the belly of the wave node.In addition,the velocity of water droplets in the sound field is influenced by the viscosity of emulsion and oil-water density;When the ultrasonic intensity is lower than the critical value,it shows the result of demulsification,and when the ultrasonic intensity exceeds the critical value,the result of ultrasonic irradiation is emulsification.The optimal combination of test parameters and the primary and secondary order of the influence of each parameter on the dehydration effect can be obtained by orthogonal experimental design and numerical analysis,and the empirical formula of dehydration rate obtained by multivariate linear regression analysis can predict the final dehydration effect of crude oil in a certain range according to the change of physical parameters of crude oil.The research results of this paper can provide reference for the selection of optimal dehydration parameters of crude oil,provide basis for the development of high efficiency dehydration technology,and lay a foundation for the research of new dehydration technology and dehydration mechanism.