Gas scrubbers offer two options for removing soluble gases, mists, or particulate matter:
—either by gas absorption or by interception.
The absorption of soluble gases involves the transfer of toxic gases from a gas stream to a liquid phase. The gas absorption process involves several key factors, such as the gas’s solubility or chemical reactivity. The gas is removed through the scrubbing liquid.
Interception is defined as the impact of the contaminant and its removal from the air stream. This is where the particles strike the media and are washed away through a cycle of humidification and cooling, causing them to rise to a certain level where they are removed by impact against the plate.
One of the most effective and common techniques used in gas scrubbers is to subject the gases to a gas-liquid absorption process.
To accomplish this, the contaminated gas is introduced at the bottom of the scrubbing tower and circulated to the top. Inside the tower, the scrubbing liquid flows from the top and is distributed throughout the column to absorb the contaminants and thus clean the air.
The type of liquid used inside the scrubbing tower will depend on the contaminants to be removed; commonly used liquids include:
Water, an acidic solution, an alkaline solution, sodium hypochlorite, potassium permanganate, or a combination of liquids, as appropriate. If the contaminants in the gases result from the handling of nitrogen, they can be absorbed by an acidic medium; however, if they result from the use of sulfur, these particles are susceptible to absorption by an alkaline or oxidizing liquid, and in other cases