Gas purification techniques

Wet lime scrubbing
The wet lime sorption process combines the advantages of gas scrubbers and (semi) dry lime sorption. This industrial gas removal technique is especially applied for the desulphuration of smoke gases whereas also the other acid forming components are bound. At wet lime sorption slurry of limestone (CaCO₃) becomes misted in spray column. In the presence of SO₂ gypsum (CaSO₄.2H₂O) is formed. In its original implementation the process existed from two absorbers and oxidation unit. In the absorber SO₂ to limestone it is absorbed, where calcium sulphite arises. In the oxidation barrel this is converted at a relatively low pH (5.5 - 6) to dehydrated gypsum, CaSO₄.2H₂O. The gypsum is afterwards drained.
The advantages of the basic scrubber are: The used sorbens, limestone, is cheap In comparison with the semi dry systems are there no need to place a substance filter behind the engine The sorbens are used in stochiometric proportion of 1 High efficiency is possible Much experience Reliable Both SO₂ and SO₃ are removed Re usable product Can be used at relatively high temperatures (50 - 80°C) The disadvantages are: For a good quality gypsum the disturbing components( pollutants) must be removed in a preceding step Effluent that must be treated High water usage (8 - 20 l/Nm³) The wet lime scrubber are used in for example the effluent installations and electricity call centers. Click here for more overview air treatment and for the solubility of SO_2. For more books and reading information see our website: Air treatment books overview

Gas purification techniques

Wet lime scrubbing