Wet Electrostatic Precipitator (WESP) A Wet Electrostatic Precipitator (WESP) is an advanced air pollution control device designed to remove fine particulate matter, aerosols, and mist from industrial exhaust gases. Unlike dry electrostatic precipitators, WESPs use a liquid (typically water) to collect and flush away captured particles, making them highly effective for handling sticky, corrosive, or high-resistivity dust that may be challenging for dry systems. Working Principle WESPs operate on the same fundamental principle as dry ESPs: ionization and electrostatic attraction. The process involves three key stages: 1. Corona Discharge: High-voltage electrodes (discharge electrodes) ionize the gas stream, charging the particles. 2. Particle Collection: The charged particles migrate toward grounded collection surfaces (tubes or plates) due to electrostatic forces. 3. Wet Removal: A continuous or intermittent water film washes the collected particles off the surfaces, preventing re-entrainment and maintaining efficiency. The liquid also helps neutralize resistivity issues, which can hinder particle collection in dry systems. Key Components - High-Voltage Power Supply: Generates the electric field for ionization. - Discharge Electrodes: Emit corona discharge to charge particles. - Collection Surfaces: Typically made of corrosion-resistant materials (e.g., FRP, stainless steel). - Spray/Wash System: Distributes water to clean electrodes and surfaces. - Mist Eliminator: Removes entrained droplets from the cleaned gas stream. Advantages - High Efficiency: Capable of capturing submicron particles (>99% efficiency). - Handles Sticky or Corrosive Particles: Ideal for sulfuric acid mist, tar, or sticky dust. - No Re-entrainment: Wet collection prevents particles from returning to the gas stream. - Compact Design: Often smaller than dry ESPs for equivalent performance. Applications WESPs are widely used in industries with challenging emissions, including: - Chemical and petrochemical plants (acid mist, VOCs). - Metallurgical processes (metal fumes, oxides). - Waste incineration (dioxins, heavy metals). - Semiconductor manufacturing (etching gases). Maintenance Considerations Regular cleaning and corrosion-resistant materials are critical due to the wet environment. Water treatment may be required to prevent scaling or fouling. Conclusion WESPs offer a robust solution for industries requiring high-efficiency particulate and mist removal. Their ability to handle difficult pollutants makes them indispensable in modern air pollution control systems.