The flue gas is drawn from the boiler by the ID fans into the Flue Gas Desulphurisation (FGD) ductwork.The gas is forced through the FGD plant by a booster fan. Once in the FGD ducting the gases pass through a heat exchanger before entering the absorber tower. The purpose of the heat exchanger is to cool the inlet flue gas to 90 degrees C and to reheat the treated gas to above 80 degrees C giving the outlet gas the buoyancy required to take it through the chimney.

Once inside the absorber the gas comes into contact with a limestone slurry mixture (in keeping with our strict environmental policies E.ON does not use limestone from national parks). The slurry is sprayed from banks of nozzles situated towards the top of the 50 metre tower. The limestone slurry is pumped up to the sprays at the top of the absorber by Warman heavy duty pumps. These pumps are the largest of their type in the world and are capable of circulating in excess of 8,000 tonnes of slurry an hour.

When the warm gas comes into contact with the limestone slurry a chemical reaction occurs between the Sulphur Dioxide (SO₂) in the gas and the limestone.

This reaction removes the SO₂ from the flue gases and converts the limestone into Calcium Sulphite (the limestone slurry also removes up to 95% of the Hydrogen Chloride present in the flue gas).

This Calcium Sulphite and limestone slurry then falls to the base of the absorber where it is injected with compressed air. The compressed air oxidises the calcium sulphite and converts it to gypsum (Calcium Sulphate).

The cooled, treated flue gas then passes through demisters before passing back through the heat exchanger and then to the chimney. The job of the demisters is to remove any slurry from the wet gas to prevent carry over of moisture and gypsum into the outlet gas ducting and subsequently into the heat exchanger, where it could result in blockage of the elements.