An Exhaust Gas Cleaning System (EGCS), commonly known as a scrubber, is used to remove pollutants from exhaust gases before they are released into the atmosphere. These systems are widely used in industries such as marine shipping, power plants, and chemical manufacturing to reduce harmful emissions like sulfur oxides (SOₓ), nitrogen oxides (NOₓ), and particulate matter (PM).

Types of Exhaust Gas Cleaning Systems

1. Wet Scrubber

• Open-loop: Uses seawater as a natural alkaline absorbent.

• Closed-loop: Uses a chemical reagent like sodium hydroxide (NaOH) in a recirculating system.

• Hybrid: Can switch between open and closed-loop modes.

• Uses a liquid (usually water or an alkaline solution) to absorb and neutralize pollutants.

• Subtypes:

2. Dry Scrubber

• Uses dry sorbents (e.g., lime or activated carbon) to absorb or react with pollutants without water usage.

• More common in power plants and industries where water use is restricted.

3. Electrostatic Precipitators (ESP)

• Uses electrostatic charges to remove fine particles from exhaust gases.

• Often used in combination with wet or dry scrubbers for enhanced efficiency.

How It Works (Wet Scrubber Example)

1. Exhaust gases enter the scrubber through an inlet duct.

2. Scrubbing liquid is sprayed into the exhaust flow, reacting with pollutants.

3. Pollutants are neutralized (e.g., SO₂ reacts with alkaline solution to form harmless salts).

4. Cleaned gases exit the system, while the used scrubbing liquid is collected for treatment or disposal.

Applications

• Marine Industry: Compliance with IMO 2020 sulfur cap regulations.

• Power Plants: Removing SO₂ from coal-fired plant emissions.

• Chemical & Manufacturing Plants: Controlling toxic gas emissions.