Intermittent energization on electrostatic precipitators

Abstract

It is well-known that back corona seriously affects electrostatic precipitator (ESP) performance in many applications when collecting high resistivity dust. In order to achieve a good performance for high resistivity dust, it is essential for an ESP to be provided with the means to reduce or repress the formation of back corona. As one of the countermeasures to overcome this problem, authors et al. originally developed and commercialized a novel energization method called “Intermittent Energization” (IE), which intermittently blocks the secondary current by a periodical blocking of the a.c. primary current of a T-R (High Voltage Transformer Rectifier) set with thyristors. Parametric tests, which were performed on a pilot ESP at a test facility and fullscale plants for dust of different resistivity levels, showed that IE can effectively mitigate the degradation of collection performance for highly resistive dust and at the same time achieve a marked reduction in power consumption for relatively low cost. In order to understand the fundamental characteristics of IE, this paper firstly describes its principle with the results of the change of appearance of back corona, flying path of the particles, the charge-to-mass ratio of the particles and then introduces an outline of IE with the relationship between migration velocity and intermittent duty for dusts of different resistivities and finally summarizes its effect, features and operational techniques based upon the operational results obtained from various commercial applications.