Scrubber System

There are numerous industrial processes in which pollutant gases are produced that must be treated before being emitted into the atmosphere. An effective technique consists of subjecting the gases to a gas-liquid absorption process. The gases to be treated enter through the bottom of one or more absorption or scrubber towers, partially filled with a liquid (e.g. water, acid solution, alkaline solution, sodium hypochlorite or potassium permanganate) or a combination of liquids, which absorb the pollutants present in the gas.

The gas leaves the scrubber without the pollutants being present and may be emitted into the atmosphere. Pollutants that are satisfactorily eliminated through a gas-liquid absorption process are SO2 and the NOX of the combustion gases, the hydrogen sulphide from wastewater treatment plant, COV, carbon monoxide, etc.

• The contaminant and the liquid must be compatible; i.e. the solubility of the former in the second must be sufficiently high.
• The contact surface must be large enough for there to be no limitation of transfer of the contaminant to the absorbent liquid.
• The contact of the contaminants present in the gaseous flow with the liquid depends on the type of absorption tower.

As it passes through the scrubbing tower, polluted air is washed at low speed inside a large contact surface. It is very important to use the correct type of absorbent during this process to ensure greater gas / liquid contact. Once purified, the air goes to the next stage or is released directly into the atmosphere.