6533b827fe1ef96bd128641e

RESEARCH PRODUCT

Application of circuit theory for extraction of water from oil

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This paper discusses optimization of the performance of a pulsed dc electrostatic coalescer, a device that is used in the oil industry to increase the speed of separation of water from a water-in-oil emulsion. A previously found criterion for optimum performance, the charge hypothesis, is reviewed. Analysis by circuit theory shows that the performance may be improved through selecting an optimum switching frequency and duty ratio, improving the design of the pulse train generator, and making physical modifications to the coalescer apparatus. The addition of an external charging circuit is beneficial. Experiments on the modified system could contribute to a better understanding of the physics of the on period. The analyses further show that it is advantageous to have a thin layer of insulation, and that the insulation could be replaced by an external capacitor. The analytical circuit model gives important insight into the physical behavior of the system, which will be valid also for a geometry where the circuit parameters cannot be found analytically; charge separates in the on period, followed by a relaxation in the off period, and if the frequency or duty ratio is not relatively close to the optimum, the coalescer may not perform as expected. Copyright 2011 John Wiley & Sons, Ltd.