Study On Droplet Coalescence Characteristics As Well As Demulsification Applying A High Electrostatic Voltage

Electrostatic coalescence can improve separation efficiency of emulsion, reduce the equipment area and energy consumption. Electric field is widely used in practical production to break the emulsion, such as crude oil dehydration, secondary oil recycling and the treatment of industrial waste liquid. We need to make further research on each scheme. Because there’s variety of voltage loading schemes, and the influence of each scheme is complicated. This paper studied characteristics of deformation, rupture and coalescence of the droplet by using the electrostatic field of bare electrode, at the same time, this paper contains the experiment about deformation and fracture of single droplet, and the coalescence of the droplets. The analysis about motion of droplet coalescence properties under the action of electric field is also discussed here. The following is conclusion of this paper:(1) Because the force of electric field on the surface of both ends of the droplets is different, spherical droplet becomes oval. And with the continuous increase of electric field force, the droplet deformation will also continue to increase. When reaching the critical electric field, the droplet ruptures.(2) Droplet coalescence rate will be faster with the increase of the electric field when the diameter of the droplet is constant;the bigger the diameter of droplet is,the faster it will combine when the voltage on-load is constant. And the coalescence process can be divided into two parts: when the center distance of two droplets is much more greater than the droplet diameter, the droplet can be regarded as point charge; when the surface distance is less than the droplet diameter, there will form a layer of film between the droplets, which impede droplet and coalescence.(3) High voltage electrostatic field can significant influence the droplet diameter of dispersed phase in the emulsion, it is called the demulsification of emulsion. In the experiment, the demulsification effect is obvious when the voltage is about 3000 V, the droplet diameter increased significantly; when the voltage is about 8000 V, the droplet will break into tiny proplets, which means the demulsificant fails. It will be seen from the experiment that the electric field intensity has a maximum, when the electric field intensity is greater than it, the demulsification will be failure.