Fume Extraction. (wet scrubbers/venturi scrubbers)

Wet scrubbers are air pollution control devices that use liquid to remove particles or gases from exhaust streams. The particles are captured by and incorporated into liquid droplets. these droplets must then separated from exhaust stream.

In typical Venturi scrubbers, the gas stream enters from the top and passes down the converging section to the throat. The liquid is injected near the throat entrance. The gas stream with in throat, moving at velocities between 15000 and 40000 ft/min. Atomizes and accelerates the water droplets.

Venturis are the most commonly used scrubber for particle collection and are capable of achieving the highest particle collection efficiency of any wet scrubbing system. As the inlet stream enters the throat, its velocity increases greatly, atomizing and turbulently mixing with any liquid present.

The atomized liquid provides an enormous number of tiny droplets for the dust particles to impact on. These liquid droplets incorporating the particles must be removed from the scrubber outlet stream, generally by cyclonic separators.

Particle removal efficiency increases with increasing pressure drop because of increased turbulence due to high gas velocity in the throat. Venturis can be operated with pressure drops ranging from 12 to 250 cm (5 to 100 in) of water.

Venturi scrubbers can have the highest particle collection efficiencies (especially for very small particles) of any wet scrubbing system.

Venturi scrubbers have been designed to collect particles at very high collection efficiencies, sometimes exceeding 99%. The ability of venturis to handle large inlet volumes at high temperatures makes them very attractive to many industries; consequently, they are used to reduce particulate emissions in a number of industrial applications.

Venturi scrubbers