Search results for "Pulsed DC"
showing 3 items of 3 documents
Electrostatic field theory and circuit analysis in the design of coalescers with pulsed dc voltage
2009
This paper presents a mathematical analysis of the electric field and interfacial free charge experienced by the emulsion in an electrostatic coalescer that is subjected to a pulsed dc voltage. Previous work in this area is re-assessed, but the analysis is expanded. A novel static analysis of the system is presented, giving valuable physical insight. It becomes obvious that there must be a limited range of frequencies that are effective in a pulsed dc scheme. Thereafter, analytical expressions for the steady-state solution, where both the switching frequency and duty ratio (or mark space ratio) can be varied, are presented for the first time. These expressions are used to derive voltage and…
Application of circuit theory for extraction of water from oil
2011
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 physic…
Vacuum electrical breakdown conditioning study in a parallel plate electrode pulsed dc system
2019
Conditioning of a metal structure in a high-voltage system is the progressive development of resistance to vacuum arcing over the operational life of the system. This is, for instance, seen during the initial operation of radio frequency (rf) cavities in particle accelerators. It is a relevant topic for any technology where breakdown limits performance and where conditioning continues for a significant duration of system run time. Projected future linear accelerators require structures with accelerating gradients of up to 100 MV/m. Currently, this performance level is achievable only after a multimonth conditioning period. In this work, a pulsed dc system applying voltage pulses over paral…