Chlorine scrubber, also known as a chlorine gas scrubber or chlorine absorption system, is a device used to remove chlorine gas from the air or gas streams in industrial settings, laboratories, water treatment plants, and other environments where chlorine gas might be released. Chlorine gas is toxic and poses serious health and environmental risks, so it's important to effectively remove it from the air to ensure safety.

Here's how a typical chlorine scrubber works:

Absorption Tower or Chamber: The core component of a chlorine scrubber is an absorption tower or chamber. This is where the process of removing chlorine gas takes place. The tower is usually packed with a material that has a high affinity for chlorine gas. Common materials used for this purpose include caustic soda (sodium hydroxide) solution or other alkaline solutions.

Gas Inlet: The chlorine gas-laden air is introduced into the bottom of the absorption tower. The gas flows upward through the tower, counter to the flow of the absorbing solution.

Contact with Absorbent: As the chlorine gas rises through the tower, it comes into contact with the absorbing solution, which can be a liquid caustic soda solution. Chlorine gas dissolves in the solution due to a chemical reaction that forms various chloride compounds.

Chemical Reaction: The primary chemical reaction that occurs is between chlorine gas (Cl2) and caustic soda (NaOH):

Cl2 + 2NaOH → NaCl + NaClO + H2O

This reaction produces sodium chloride (table salt) and sodium hypochlorite as well as water.

Formation of Chloride Compounds: The sodium chloride and sodium hypochlorite formed during the reaction dissolve in the solution. These compounds are not gaseous and thus are effectively removed from the gas stream.

Scrubbed Gas Exit: The gas, now with a significantly reduced concentration of chlorine, exits the top of the absorption tower.

Monitoring and Maintenance: To ensure the efficient operation of the chlorine scrubber, various parameters such as the flow rate of gas, concentration of chlorine, and the pH level of the absorbing solution need to be monitored and controlled. The absorbing solution might need periodic replenishment or replacement, as the absorption process results in the consumption of the caustic soda solution.

Safety Measures: Scrubbers often incorporate safety features like emergency shutdown systems and alarms to alert personnel in case of malfunctions or excessively high chlorine levels.

Chlorine scrubbers are an essential safety measure in industries where chlorine gas is produced or used. They help prevent the release of chlorine gas into the environment, thereby protecting workers, the surrounding community, and the environment from potential harm.