The production of pulsed E.H.T. voltages for electrostatic coalescence

Abstract

The use of an electric field, applied between immersed electrodes, is known to promote the separation of water-in-oil type dispersions or emulsions. Recent work has established that pulsed unidirectional voltages applied to electrodes insulated from the liquids is an efficient means of promoting phase disengagement particularly for dispersions with a high conducting phase content. The range of applications is thus extended to include chemical engineering operations such as solvent extraction and crude oil dehydration. It has been shown that the rate of coalescence is not only a function of pulse amplitude but also its shape, mark space ratio and frequency; all of these parameters having physical optimum values. There is, at present, no commercially available package capable of generating a pulsed EHT output of any form in the required frequency range (0.1 – 50 Hz). This paper therefore describes an existing arrangement for laboratory use and a more compact solid state version. The implementation of monitoring and external control facilities is also briefly mentioned.