Flue Gas Desulfurization System (FGD)

Flue Gas Desulfurization System (FGD) is used to remove sulfur dioxide and other sulfur-containing acidic components from industrial flue gas. The system brings the gas into contact with a suitable alkaline reagent, allowing sulfur compounds to be absorbed and converted into reaction products.

Wet FGD is commonly configured with an absorber tower, slurry circulation system, reagent preparation equipment, spray headers, mist eliminator, and supporting pumps and piping. Hot flue gas enters the absorber and is distributed through the spray zone, where alkaline slurry contacts the gas.

Sulfur dioxide dissolves into the liquid phase and reacts with the alkaline components in the slurry. The treated gas then passes through the mist eliminator, which removes entrained liquid droplets before the gas leaves the absorber.

Different desulfurization processes can be selected according to the flue gas characteristics. Wet, dry, and semi-dry configurations differ in reagent form, gas-liquid contact method, reaction conditions, and by-product handling.

The system design depends on flue gas volume, inlet temperature, SO₂ concentration, moisture content, reagent properties, residence time, and required removal conditions. Pumps, valves, ducts, sensors, and control equipment are arranged to maintain the required gas and reagent flow.

Main Components

• FGD absorber tower

• Gas inlet and outlet

• Spray system

• Absorbent slurry circulation system

• Reagent preparation unit

• Circulation pumps

• Mist eliminator

• Slurry collection section

• Piping and valves

• Monitoring and control system

Desulfurization Processes

Wet FGD

Flue gas contacts an alkaline slurry inside an absorber. SO₂ is transferred from the gas phase into the liquid and reacts with the absorbent.

Dry FGD

A dry alkaline reagent is introduced into the flue gas and reacts with acidic sulfur compounds. The resulting solid particles are subsequently separated from the gas stream.

Semi-Dry FGD

An absorbent slurry or solution is atomized into the hot flue gas. Water evaporates while the alkaline material reacts with sulfur compounds, producing dry reaction products.

Operating Factors

• Flue gas flow rate

• Inlet gas temperature

• SO₂ concentration

• Reagent concentration

• Gas-liquid contact time

• Slurry circulation rate

• Moisture content

• Pressure drop

Applications

• Power plant flue gas treatment

• Industrial boilers

• Cement production

• Steel and metallurgical processes

• Waste incineration

• Chemical processing

• Mineral processing

• Industrial combustion systems