Wet Scrubber

Air scrubbers are commonly used in process-air applications to eliminate potentially harmful dust and pollutants. A liquid, in general water added with active chemicals adapted to the process, is sprayed in to the air flow. Aerosol and gaseous pollutants in the air stream are removed by either absorption or chemical reactions with the water solution.

Wet Scrubber Basic Configurations

The basic scrubber configurations are:
1. Orifice scrubbers - air or gas velocity is increased through an orifice - increased turbulence atomize the water droplets
2. Venturi scrubbers - air or gas velocity is increased through a venturi shape - increased turbulence atomize the water droplets
3. Fiber-bed scrubbers - air passes through wet-laden fiber mats where mists are collected. Not suited if solid particles are present in the air since the fiber mats may plug
4. Mechanical scrubbers - a mechanical driven rotor produces the fine water droplets in the air
5. Impingement-plate scrubber - vertical scrubber with horizontal plates, air flows from bottom to top, water flows from top to bottom
6. Spray nozzle scrubbers - water are sprayed with high pressure through nozzles to produce the droplets in the air

Typical Scrubber Data

• Cleaning efficiency: 70% of fine dust and 80% of coarse dirt
• Air velocity through the washer: 2 - 3 m/s
• Air flow pressure drop resistance: 50 - 140 N/m2
• Water pressure before nozzles: 100 - 170 kN/m2
• Water consumption: 0.45 - 0.55 l/m3 air (depends on the temperature of the process air)