Wet vs Dry Scrubber 

Wet scrubber  is a device that removes pollutants from a furnace flue gas or from other gas streams. In wet scrubbers, the polluted gas stream is brought into contact with the scrubbing liquid, by spraying it with the liquid, by forcing it through a pool of liquid so as to remove the pollutants. Wet scrubbers remove pollutant gases by dissolving or absorbing the pollutants into the liquid.

Advantages and Disadvantages of Wet Scrubbers:

Advantages:

  1. Relatively small space requirements
  2. Can collect gases as well as particulates
  3. Can handle high-temperature, high-humidity gas streams
  4. Capital cost low and after the particulate matter is collected, it cannot escape from hoppers or during transport.
  5. Various dry dusts are flammable. Using water eliminates the possibility of explosions.
  6. High collection efficiencies on fine particulates
  7. Handle gas streams containing flammable or explosive materials.
  8. Wet scrubbers can neutralize corrosive gases.

Disadvantages:

  1. Possible creation of water-disposal problem and the product collected is wet.
  2. Moist exhaust gas precludes use of most additional controls
  3. Pressure-drop and horsepower requirements are possibly high and Solids buildup at the wet-dry interface might be a problem
  4. Relatively high maintenance costs and Must be protected from freezing
  5. Low exit gas temperature reduces exhaust plume dispersion

 Dry scrubber :

A dry Scrubbing system does not saturate the flue gas stream that is being treated with moisture. In some cases no moisture is added; while in other only the amount of moisture that can be evaporated in the flue gas without condensing is added. Dry scrubbers generally do not have wastewater handling/disposal requirements. Dry scrubbing systems are used to remove acid gases(such as SO2 and HCl) primarily from combustion sources

Advantages and Disadvantages of Dry Scrubbers

Advantages:

  1. No wet sludge is produced.
  2. Relatively small space requirements
  3. Can collect acid gases at high efficiencies
  4. Can handle high-temperature gas streams
  5. Dry exhaust allows addition of fabric filter to control particulate

 Disadvantages

  1. Acid gas control efficiency not as high as with wet scrubber