Wet scrubbers are used in utilities, paper mills, and chemical plants to remove sulfur dioxide (SO2) and other pollutants from gas streams. Undesirable pollutants are removed by contacting the gases with an aqueous solution or slurry containing a sorbent. Lime / limestone systems are most common for SO2 removal but magnesium oxide (MgO) slurry is sometimes used as an alternative.
After fly ash removal, the flue gas enters the scrubber (Figure 1) where it comes in contact with the MgO slurry. The SO2 is absorbed in the scrubber slurry and forms insoluble magnesium sulfite (MgSO3) as in the equation below.
MgO(s) + SO2(g) → MgSO3(s)