Question

Draw and neat diagram and explain working of Venturi Scrubber.

Answer 1

Venturi scrubbers are part of the group of air pollution control systems known as wet scrubbers. These are often installed to remove fine particles from volatile, hazardous or corrosive gas streams, or gas streams containing solid materials that are difficult to handle. These scrubbers use a scrubbing liquid (often water) to capture and remove pollutants.
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.
  
  Applications:
• The ability of venturi scrubber to handle large gas inlet volumes at high temperatures makes it applicable to many industries. It is capable of removing particulate matter or gases from an industrial exhaust or flue gas stream, handling explosive and flammable gases safely, removing solids, mists, and gases simultaneously while also providing cooling of hot gas stream and neutralising corrosive gases and dust.
  Venturi scrubber are applied in chemical industry for the removal of dust and aerosols, metallurgy for several types of degasses, waste combustion installations, glass industry, manure production, pharmaceutical industry, plastic industry.