Scrubber Basics

In a scrubber, air is drawn through a mist of water made by spray nozzles, then through separators where dust and particles with water droplets are removed from the air flow

Air scrubbers are used for applications that require elimination of potentially harmful pollutants from the air. They use liquid sprays to remove aerosol and gaseous pollutants from an air stream and the gases are removed either by absorption or chemical reaction. Scrubbers may be used to fume and gas abatement, process air cleansing and dust collection.

Some common scrubber properties:

• Cleaning efficiency : 70% of fine dust, 80% of coarse dirt
• Air velocity through the washer : 2 - 3 m/s
• Air glow resistance : 50 - 140 N/m²
• Water pressure nozzles : 100 - 170 kN/m²
• Water quantity : 0.45 - 0.55 l/m³ air

Scrubber humidifying efficiency

The humidifying efficiency of the scrubber may be expressed as:

E = (t₁ - t₂) / (t₁ - t_w) 100% (1)

where

E = Humidifying efficiency (%)

t₁ = initial dry bulb temperature (^oC)

t₂ = final dry bulb temperature (^oC)

t_w = initial wet bulb temperature (^oC)

Scrubber Efficiencies

Typical scrubber efficiencies may be

• 60-70 % with one bank of nozzles downstream
• 65-75 % with one bank of nozzles upstream
• 85-100 % with two banks of nozzles

Note! Low temperature scrubbers are potential sources for the Legionella disease.

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