Working Principle of Wet Electrostatic Precipitator

Wet Electrostatic Precipitator (WESP) is a high-efficiency dust removal device that integrates the electrostatic precipitation principle and wet ash cleaning technology. It is mainly used to treat fine pollutants such as dust, acid mist and PM2.5 in humid gas, and is one of the core equipment for realizing the "ultra-low emission" of industrial flue gas at present.

Core Working Principle

Its dust removal process consists of three core stages. The basic principle is consistent with that of dry electrostatic precipitators, and the key difference lies in the ash cleaning method:

Charging Stage: A high-voltage direct current is applied between the anode plate and cathode wire. Corona discharge ionizes the gas to generate a large number of ions. Particulate matter such as dust and droplets in the flue gas gets charged after colliding with charged particles.

Collection Stage: Driven by electric field force, the charged particulate matter moves toward the dust collection electrode (anode plate/tube) with opposite polarity and deposits on the electrode surface.

Ash Cleaning Stage: Unlike dry electrostatic precipitators which adopt mechanical rapping for ash removal, wet electrostatic precipitators form a continuous liquid film by spraying water, which washes the deposited dust down to the ash hopper for discharge, fundamentally avoiding secondary dust emission.

Main Classifications and Structural Characteristics

It can be divided into two types according to structural form, with the following key differences:

| Classification Dimension | Category | Core Characteristics |

| ---- | ---- | ---- |

| Flue gas flow direction | Cross-flow type (horizontal type) | Similar in structure to dry electrostatic precipitators, mostly plate-type structure; flue gas flows in and out horizontally, suitable for working conditions with large flue gas volume |

| Flue gas flow direction | Vertical-flow type (vertical type) | Mostly tubular structure; flue gas flows in and out vertically. Under the same cross-sectional area for gas passage, its efficiency is twice that of the cross-flow type, featuring smaller footprint and higher efficiency |

| Material of dust collection electrode | Corrosion-resistant conductive metal dust collection electrode | Only requires regular flushing, low water consumption, recyclable and reusable wastewater, almost no secondary pollution; it is the mainstream type in current applications |

| Material of dust collection electrode | Non-metallic conductive water-film dust collection electrode | Conductive film is formed by water spraying; there are risks of corrosion and wastewater treatment. It is only applicable to scenarios with low dust concentration and high purification requirements |

Comparison of Advantages and Disadvantages

| Advantages | Disadvantages |

| ---- | ---- |

| Extremely high dust removal efficiency. The removal efficiency of fine particulate matter including PM2.5, SO₃ acid mist and aerosol can reach more than 90%, and it can stably meet the ultra-low emission requirement of flue gas emission concentration ≤5mg/m³ | The process generates dust-laden wastewater, which requires a supporting wastewater treatment system and carries a certain risk of secondary pollution |

| It can efficiently treat difficult-to-handle dust that is high-temperature, high-humidity, sticky and with high specific resistance, adapting to complex flue gas working conditions | The equipment has high anti-corrosion requirements, and its overall construction cost and operating cost are higher than those of dry electrostatic precipitators |

| No mechanical rapping device, stable and reliable operation, low tendency of secondary dust emission | Thermal insulation and anti-freezing measures are required for operation in cold regions, and the treated flue gas has high moisture content |

| Modular design, compact structure, customizable on demand and small footprint | |

Mainstream Application Scenarios

As terminal advanced treatment equipment for flue gas, it is widely used in various industrial environmental protection renovation projects:

Coal-fired Power Plants: Usually arranged after the wet desulfurization system for advanced purification of flue gas to solve the problems of gypsum rain and white smoke from chimneys, serving as the core equipment for ultra-low emission.

Iron and Steel Metallurgy Industry: Used for advanced dust removal of flue gas from sinter machine hood and primary flue gas of converters to meet increasingly stringent environmental emission requirements.

Other Industrial Scenarios: Covering cement manufacturing, mineral mining, pigment production, pharmaceutical production, food processing, die-casting heat treatment, electroplating and many other fields. It can targetedly treat complex pollutants such as sticky dust and steam oil mist.

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