Flue gas desulphurization

FGD Systems can be divided into three basic categories, due to environment in which desulfurization reaction is carried out:

  • "wet" method
  • "dry" method
  • "semi-dry" method

Among these three above mentioned methods of flue gas desulphurization, the most commonly used method is based on wet scrubbers (especially for large projects), not only because of its effectiveness, that is often more than 95%, but also due to of its reliability that ensures the availability of the installation at a value of <99%. Additionally, the wet process, in contrast to the other, allows to obtain as a reaction product gypsum (product for resale), If the method uses a neutralizing reagent based on lime, while the product of the other installations (dry and semi-dry) are waste to landfills.


Wet flue gas desulphurization

Solutions offered by Control Process S.A. allows to use in wet flue gas desulphurization installations following types of sorbents:

  • sorbents based on calcium
    - calcium carbonate - CaCO3
    - calcium oxide – CaO
    - calcium hydroxide - Ca(OH)2
    - dolomite - CaCO3·MgCO3
  •  sorbents based on potassium, magnesium and soda
    - magnesium oxide and hydroxide - MgO and Mg(OH)2
    - soda – NaOH
    - ammoniacal sodium carbonate - Na2CO3
    - sodium bicarbonate - NaHCO3
    - potassium sulphate - K2SO3
  • ammonia
  • sea water (magnesium carbonate contained in this type of water – MgCO3

Installation of wet flue gas desulphurization requires construction of installation for purification of water separate from the desulphurization products (this necessity does not occur for other methods).


Semi-dry flue gas desulphurization

Semi-dry flue gas desulphurization installations typically use a sorbent based on calcium oxide or calcium hydroxide (Hydrated lime is more reactive) this process does not require reconstruction of a water purification installation, but manufactures products which must be disposed (usually through storage). Control Process S.A. offers semi-dry flue gas desulphurization installations with the efficiency of <98%.


Dry flue gas desulphurization installations

These are the simplest and most economical flue gas desulphurization installations. They do not require special extended elements, due to the fact that the sorbent injection (based on calcium or sodium) takes place directly in the boiler or in the case of injection at moderate temperatures in the "venturi throat" of reactor. The effectiveness of this method is varied, it depends on the process conditions and reagent used for the reaction, but does not exceed 50%.