Wet limestone scouring is the most proficient methods for expelling SO2 in the stack gases depleted to the atmosphere.
This limestone slurry, a blend of limestone and water, is provided from the limestone slurry tank to the safeguard. Slurry stream is controlled by the slurry control valve, with distribution siphons moving the limestone slurry to the header. These distribution siphons keep the limestone slurry streaming to the header in order to keep showering it into the pipe gas from the highest point of the safeguard.
Pipe gas from the evaporator goes through a gas-to-gas heat exchanger to expel abundance heat. It at that point streams into the safeguard the opposite way to the shower of limestone slurry. After the pipe gas is splashed with wet limestone, it leaves the safeguard. It at that point goes through the gas-to-gas heat exchanger, and is at long last vented to environment through the stack.
In the safeguard, SO2 contained in the pipe gas is retained due to the compound response between the SO2 and the limestone slurry. The compound response recipe for this desulfurization procedure is:
CaCO3 + SO2 + 2 H2O +½ O2 => CaSO4 + 2 H2O + CO2