The equipment and the processes are similar to those in limestone scrubbing. Lime Scrubbing offers better utilization of the reagent. The operation is more flexible. The major disadvantage is the high cost of lime compared to limestone.

• Lime and Limestone scrubbing lead to deposits inside spray tower.

• The deposits can lead to plugging of the nozzles through which the scrubbing slurry is sprayed.

• The Dual Alkali system uses two regents to remove the sulfur dioxide.

• Sodium sulfite / Sodium hydroxide are used for the absorption of sulfur dioxide inside the spray chamber.

• The resulting sodium salts are soluble in water,so no deposits are formed.

• The spray water is treated with lime or limestone, along with make-up sodium hydroxide or sodium carbonate.

• The sulfite / sulfate ions are precipitated, and the sodium hydroxide is regenerated.