A chlorine scrubber is a system designed to remove chlorine gas (Cl₂) from industrial exhaust streams or air emissions. Chlorine is a toxic and corrosive gas, so its removal is critical for safety, environmental compliance, and equipment protection. Here’s how a chlorine scrubber typically works:

1. Gas Capture and Introduction

• The chlorine-containing gas stream is directed into the scrubber system, usually through ductwork or piping.

• The gas enters the scrubber at the bottom or side, depending on the design.

2. Contact with Scrubbing Solution

• Inside the scrubber, the gas comes into contact with a scrubbing solution, which is typically an alkaline liquid such as sodium hydroxide (NaOH) or caustic soda.

• The scrubbing solution is sprayed or distributed over packing material or trays to maximize the surface area for gas-liquid contact.

3. Chemical Reaction

• Chlorine gas reacts with the alkaline solution in a neutralization reaction. For example, with sodium hydroxide:Cl2+2NaOH→NaCl+NaOCl+H2OCl2+2NaOH→NaCl+NaOCl+H2O

• This reaction converts chlorine gas into non-hazardous byproducts: sodium chloride (NaCl, common salt) and sodium hypochlorite (NaOCl, a bleach solution).

4. Gas-Liquid Separation

• After the reaction, the cleaned gas passes through a mist eliminator or demister to remove any entrained liquid droplets.

• The purified gas is then released into the atmosphere or further treated if necessary.

5. Scrubbing Solution Management

• The spent scrubbing solution, now containing the reaction byproducts, is collected at the bottom of the scrubber.

• It may be recirculated or treated further, depending on the system design and the concentration of byproducts.

6. Monitoring and Control

• The system is equipped with sensors and controls to monitor parameters like pH, flow rates, and chlorine concentration to ensure efficient operation.

• The pH of the scrubbing solution is critical, as it must remain alkaline to effectively neutralize chlorine gas.

Types of Chlorine Scrubbers

• Packed Bed Scrubbers: Use packing material to increase gas-liquid contact.

• Venturi Scrubbers: Use high-velocity gas flow to atomize the scrubbing solution.

• Spray Tower Scrubbers: Use nozzles to spray the scrubbing solution into the gas stream.

Applications

Chlorine scrubbers are commonly used in industries where chlorine gas is produced or used, such as:

• Chemical manufacturing

• Water treatment plants

• Pulp and paper industries

• Semiconductor manufacturing

By effectively removing chlorine gas, scrubbers protect workers, the environment, and equipment from its harmful effects.