A WESP utilizes high-voltage negative DC corona discharge (45 to 70 kV) emitted from rigid barbed or star-profile discharge electrodes centered inside vertical collecting tubes. High-voltage field charging imparts intense negative electrical charges to submicron particles and sulfuric acid mist droplets. Under the electrostatic field (E), charged aerosols migrate laterally toward grounded stainless steel or alloy collecting tube walls, where an intermittent or continuous water deluge washes the collected slurry into a bottom sump without re-entrainment.

Dry ESPs suffer from two fatal failure modes on fine submicron dust: high dust resistivity causing electrical "back-corona" (sparking through the collected ash cake), and mechanical rapping re-entrainment (hopping particles back into the gas stream during plate vibration). WESPs operate in saturated gas conditions with zero electrical resistivity issues and eliminate mechanical rapping completely by using a liquid water wash film, reliably achieving over 99.5% removal on 0.1 to 1.0 µm aerosols.

The Deutsch-Anderson equation models fractional collection efficiency as: eta = 1 - exp(-we * A / Q), where we is particle migration velocity, A is total collecting area, and Q is volumetric gas flow rate. Its classical form assumes uniform gas velocity, complete cross-sectional mixing, and zero re-entrainment. In real WESP design, the Matts-Ohnfeldt modification eta = 1 - exp(-(wk * A / Q)^m) (with exponent m approx 0.5) is used to account for non-uniform gas sneakage and turbulent eddy diffusion.

Superficial gas velocity in vertical tubular WESPs is typically maintained between 1.2 and 2.5 m/s (4.0 to 8.2 ft/s). Velocities above 2.8 m/s cause aerodynamic shear that strips collected water film droplets off the tube walls (water droplet carryover). Treatment residence time inside the active electrified field must be between 1.5 and 3.5 seconds to ensure adequate electrostatic migration of ultrafine aerosols.

High-voltage support insulators operate at 50–70 kV and must penetrate the precipitator roof. If hot, saturated acid flue gas migrates into the insulator housings, condensation creates a conductive acid electrolyte film across the ceramic/quartz surface, causing instant electrical flashover and porcelain shattering. Insulator compartments must be continuously pressurized with heated, filtered purge air (at least 15°C–25°C above flue gas dew point).