Novel and efficient electrostatic pre-coalescence method and device applied to dehydration and desalt of crude oil

Abstract

The present invention discloses a novel and efficient electrostatic pre-coalescence method and a device applied to dehydration and desalt of crude oil. The invention is used for dehydration of crude oil in the system of oil-gas gathering and transportation in oil fields and for dehydration and desalination of oil refineries, therefore enables the small water particle dispersed phase in the crude oil emulsion to coalesce and grow. The core part of the device is an electrode assembly comprising an electrically conductive metal rod, multilayer cannular electrodes vertically and coaxially mounted, and tabular electrodes parallelly mounted. When high pressure alternating current is applied to the electrode assembly, the dispersed phase water particles in the crude oil emulsion undergo demulsification because of the mechanism of dielectrophoresis coalescence and vibration coalescence, thereby the dispersed phase water particles coalescing and growing up, the subsequent time of gravity settling being reduced notably and the process efficiency being improved. Moreover, the device is compact and efficient. On the basis of the mechanism of dielectrophoresis phenomenon, the dosage of chemical demulsifiers and the total operating cost can be reduced and the economical benefit of oil refineries can be improved.

Description

technical field [0001] The invention belongs to the technical field of crude oil electric dehydration and desalination, and relates to a novel high-efficiency electrostatic pre-coalescence method and equipment for crude oil dehydration and desalination. Dehydration of crude oil in subsea production systems. Background technique [0002] In a conventional electric dehydration (desalter) device, the water-in-oil type crude oil emulsion enters from the bottom of the tank, and the overall flow trend is from bottom to top. The particles begin to settle by countercurrent gravity. This layout makes the flow direction of the crude oil emulsion opposite to the settling direction of the dispersed phase water particles after coalescence, which increases the settling time of the water droplets and affects the dehydration (desalination) efficiency. Since the electrostatic coalescence of water particles grows and the gravity sedimentation of water particles proceeds simultaneously, in o...

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Problems solved by technology

But its disadvantages are: the top area of ​​the cylinder is not filled with crude oil emulsion, which limits the processing capacity of the electrostatic pre-coalescer; the treated crude oil emulsion should avoid severe shearing before entering the subsequent sedimentation and separation equipment. This causes the larger dispersed phase water particles to break again; the adaptability to the gas content and water content in the W / O crude oil emulsion is low; the treatment effect on the heavy oil emulsion is not good; only the dipole The mechanism of coalescence or oscillatory coalescence demulsification fails to fully realize the important value of dielectrophoretic phenomenon to electrostatic pre-coalescence

But its shortcoming is that the flow state of the crude oil emulsion in the coalescence part is laminar flow, which fails to make full use of the collision and coalescence of turbulent water particles in the dispersed phase, and the laminar flow state limits the electrostatic pre-coalescer The processing efficiency of the crude oil emulsion; the vortex formed after the crude oil emulsion passes through the spoiler may cause the larger dispersed phase water particles to break again after coalescence; it is difficult to handle high-viscosity crude oil emulsion; only dipole coalescence or oscillatory coalescence is used Coagulation and demulsification mechanism, failing to utilize the dielectrophoresis phenomenon to coalesce and demulsify the small water particles in the dispersed phase; the adaptability to the water content of W / O type crude oil emulsion is low

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