Research On Demulsification Of Water-in-crude Oil Emulsion With High Frequency Electric Field And Design Of Tubular Electrostatic Coalescer

With step into the late mining of major land oilfields and rapid development of exploitation of offshore oilfields,the research and development of more efficient electric field dehydration technology is becoming more and more urgent.In this thesis,based on a series of research on demulsification characteristics of crude oil utilizing high frequency / high voltage pulsed AC electric field,a tubular electrostatic coalescer with the characteristics of honeycomb flow channel is proposed,and the design,development and performance evaluation of the tubular electrostatic coalescer were carried out by means of three-dimensional modeling,numerical simulation and experimental test.Above all,an advanced electric rheometer of Anton Paar MCR 302 was utilized for the first time in the domestic to systematically investigate the electrostatic coalescence characteristics under the high frequency electric field,in which the real crude oil sample taken from Peng Lai 19-3offshore oilfield was adopted and the effects of flow shear,electric field strength,frequency,voltage waveform,initial water cut,temperature and demulsification time were studied.The experimental results show that,for the specific emulsion system,there exist better the parameters interval or critical value for the flow shear strength,electric field strength and frequency,and the range of three voltage waveforms according to the corresponding electrostatic coalescence efficiency is that AC square wave > triangle wave > sine wave;To further verify the applying feasibility of technology combination scheme of high frequency electric field demulsifying and centrifugal dewatering,as well as to provide some references for the whole solution of the tubular electrostatic coalescence application in engineering,the experimental study on the influences of different electric field parameters,centrifugal operation parameters andemulsion water cut on the oil-water separation characteristics under the combined scheme was carried out.The results demonstrate that the high frequency / high voltage pulsed AC electric field shows great applicability either in dealing with oil emulsions of water cut of 14.38%or 57.13% with selected optimum parameters(5kV and 3kHz);Then,the design of structure of the tubular honeycomb flow channel electrostatic coalescer including the size of the key structural parts and the flow state of the emulsion were carried out.The insulation of the high voltage electrode and the distribution of the electric field strength were both investigated.After that,the author completed the drawing design of entire package of experimental prototype of tubular honeycomb flow tube electrostatic coalescer and finished the manufacturing cooperated with out processing factory;Finally,the dynamic demulsification characteristics of tubular honeycomb channel electrostatic coalescer were tested and evaluated systematically.The results show that the optimum electric field strength and frequency are different under different conditions of water cut,and the way of insulation for the high-voltage electrode surface has an important effect on the demulsification effects and power consumption characteristics for the coalescer.The research work provides a new thoughts,method and theoretical reference for the research on the demulsification characteristics of the high-frequency electric field of the crude oil emulsion.At the same time,it provides a technical reference for the research and development of the tube-type electrostatic demulsification equipment as well as the supporting application solutions in engineering.