Question

Explain principle, construction and working of venturi scrubber.

Answer 1

Principle:

• In the venture scrubber, gas laden with particulate matter passes through a constricted section of the scrubber where scrubbing liquid and gas reach high velocities, resulting in high turbulence in the liquid and gas streams, which causes liquid droplet-particle contact. The scrubbing liquid hence removes the pollutants from the gas stream.

Description and Working:

• Venturi scrubber is a venturi shaped chamber with converging and diverging sections. It consist of a third section called the throat section.
• The scrubbing liquid (generally water) is introduced at the entrance to the converging section through a nozzle.
• The inlet gas stream enters the converging section and, as the area decreases, gas velocity increases.
• The inlet gas, which is forced to move at extremely high velocities in the small throat section, shears the liquid from its walls, producing a tremendous number of very tiny droplets.
•  In the throat section, particle and gas pollutant removal occurs as the inlet gas stream mixes with the fog of tiny liquid droplets.
• The inlet stream then exits through the diverging section, where it is forced to slow down.
• Many scrubbers are available with pre-filters or final filters to further reduce emissions. Pre-filters are installed upstream of the scrubber intended to catch larger particles.
•  A final filter is often installed downstream of the scrubber, and is intended to catch fine particles that were not removed during the scrubbing process.
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