Wet Electrostatic Precipitator

1. Working Principle of Wet Electrostatic Precipitator (WESP):

A wet electrostatic precipitator converts ordinary three-phase alternating current into adjustable high-voltage pulsed direct current ranging from 0 to 80 kilovolts through rectification, conversion and voltage boosting. When the equipment is energized and operating, flue gas passes through the unit. The cathode wires (corona electrodes) suspended inside the equipment continuously emit electrons, ionizing part of the gas between the electrodes into positive and negative ions. Dust particles become charged upon contact with these ions. Following the principle that like charges repel and opposite charges attract, the charged dust particles move toward the electrode of opposite polarity: positive ions migrate to the corona electrodes, while electrons and negative ions travel toward the anode tubes (collecting electrodes). Dust suspended in the gas collides with negatively charged ions and becomes charged. Driven by the electric field, the charged dust particles move to the inner walls of the collecting electrodes, slide down the walls under their own weight, fall into the dust collection unit beneath the electrostatic precipitator and mix with the slurry. After the equipment has operated for a set period, the electric control system automatically starts the flushing water pump to activate the spray system. Within the preset duration, the spray system cleans residual dust attached to the inner walls of the anode tubes. The wastewater is discharged out of the equipment through the drain outlet of the dust collection chamber. In this way, the discharged flue gas is purified to meet national emission standards.

The wet electrostatic precipitator (hereinafter referred to as the precipitator) can be installed outside the tower or on top of the tower. It uses high-voltage pulsed direct current and electric fields to drive fine soot and dust in flue gas, accelerating their deposition on the anode surface. This removes dust particles, mist droplets, aerosols and other substances from flue gas to realize flue gas purification.

2. Introduction to the structure of the wet electrostatic precipitator (mist eliminator):

The overall structure of the electrostatic precipitator (mist eliminator) consists of a shell, anode system, cathode system, insulation box, gas distribution device, flushing system, power supply and electrical control system, etc.

3. Characteristics

WESP features high dust removal efficiency, low pressure loss, simple operation, low energy consumption, no moving parts, no secondary dust emission, low maintenance cost, short production downtime, and capability to operate below the flue gas dew point temperature. Thanks to its compact structure, it can be integrated with other flue gas treatment equipment and supports diversified design configurations.

The wet electrostatic precipitator removes dust by flushing the surface of dust collection electrodes with liquid. It can effectively capture fine particulate matter (PM2.5 dust, SO3 acid mist, aerosols), heavy metals (Hg, As, Se, Pb, Cr), organic pollutants (polycyclic aromatic hydrocarbons, dioxins), and so on. After adopting the wet electrostatic precipitator, the dust emission in wet flue gas can be reduced to below 10mg/m³ or even 5mg/m³. Its dust collection performance is independent of dust properties. It is suitable for the treatment of wet flue gas, especially the dusty flue gas after wet desulfurization in power plants and steel mills. Nevertheless, this equipment requires relatively high capital investment and needs to be used together with other dust removal equipment. Its investment technical economy and operating cost shall be evaluated from an overall perspective.