Investigation On Electrostatic Coalescence Characteristics Of Water Droplets In Heavy Oil In The Vessel Internal Electrostatic Coalescer

Heavy oil has the characteristics of high viscosity,high density and high content of gum and asphaltene.The complicate components can result in unstable process and difficult dehydration.Electrostatic coalescence is an important method to achieve deep and efficient dehydration.As the central unit of electric dehydrator,it’s imperative to reform and optimize the vessel internal electrostatic coalescer.Using electric field analogy and laboratory experiment,this paper is mainly study the electrostatic coalescence characteristics of water droplets in heavy oil in the vessel internal electrostatic coalescer.The effects of structure parameters on field distribution were investigated by electric field analogy.The effects of electric parameters,operational parameters and medium properties on coalescence characteristics and oil-water separation properties were studied by laboratory experiment.The arrangement,shape,spacing,and the thickness of the insulation were studied on electric field analogy.The results show that wire type of electrode in same size and density can achieve better electric field distribution,and prevent coalescence process from forming water layer.Thinner thickness of insulation in high voltage electrode can reach high electric field meanwhile reduce the possibility of electric breakdown.The electric field intensity,frequency,electric form,temperature and water content were studied on laboratory experiment.The results show that critical electric field intensity of heavy oil is lower than light oil.The influence of frequency on coalescence process increase at first,and then decrease,finally increase again.Sin wave performs better at high electric field intensity.With the rise of temperature or water content,the breakdown electric intensity decline.The number of very small droplets increases with higher electric field intensity after electrical dispersion.Besides,this paper investigated the influence of voltage,frequency,temperature,water content and flow rate on separation efficiency and energy consumption.The results show that voltage is the main factor in determining energy consumption of coalescer,the frequency should be adjusted property.The energy consumption increases markedly as water content increase,while temperature has fewer impacts on it.High flow rate will increase the energy consumption of unit emulsion volume.Extending electric field resident time can effectively overcome the problem of large occupation area and low treatment efficiency.