Desulphurization (Flue Gas Desulphurization)

Desulphurization is the process of removing harmful sulfur compounds, such as sulfur dioxide (SO₂), from flue gases released into the atmosphere from industrial facilities and power plants. This process is critical for complying with environmental regulations to reduce acid rain, air pollution, and adverse effects on human health.

Desulphurization with Wet Scrubber (Wet Scrubber)

Wet scrubbers are versatile systems widely used in desulphurization processes, capable of both sulfur removal and particulate matter (dust) retention. These systems bring flue gases into contact with an absorbent liquid, chemically binding sulfur dioxide and removing it from the gas stream.

Working Principle: Capture of Sulfur Dioxide

The desulphurization process in wet filters generally includes the following steps:

• Absorbent Preparation: An absorbent slurry is typically prepared by mixing alkaline substances such as limestone (CaCO₃) or slaked lime (Ca(OH)₂) with water. This slurry is the primary substance that will react with SO₂ to neutralize it.
• Gas-Liquid Contact: Flue gases are admitted to the wet filter, where they are brought into intense contact with the absorbent slurry, which is sprayed in fine droplets through high-pressure nozzles. This contact occurs through diffusion (the transfer of gas molecules into the liquid) and impact (the impact of particles on liquid droplets).
• Chemical Reaction: Sulfur dioxide (SO₂) in the flue gas reacts with calcium carbonate or calcium hydroxide in the absorbent slurry to form calcium sulfite (CaSO₃) and/or calcium sulfate (CaSO₄ - gypsum). These solid products remain in the liquid phase.
  Sample Reaction (with Limestone ):
  CaCO₃(s) + SO₂(g) → CaSO₃(s) + CO₂(g)
  CaSO₃(s) + ½ O₂(g) + H₂O(l) → CaSO₄·H₂O(s) (Gypsum)
• Product Removal: The resulting calcium sulfite/sulfate sludge is collected at the bottom of the filter and removed from the system. With appropriate treatment (especially in the form of gypsum), this sludge can be utilized in the construction industry or other industries.
• Clean Gas Output: Clean flue gas, free of sulfur dioxide and with reduced particle load, is released into the atmosphere through the filter.

Advantages and Application Areas

Wet filter desulphurization systems offer high SO₂ removal efficiency and also contribute to particulate matter control. They are particularly preferred in industries that use high-sulfur fuels or produce high SO₂ emissions, such as thermal power plants, cement plants, metallurgical plants, and the chemical industry.