ABSTRACT
The earliest experience with lime or limestone wet scrubbing took place in England during the 1930s, where closed-loop lime and limestone Sulphur dioxide (SO2) scrubbers were installed on full-scale boilers. Imperial Chemical Industries (ICI) and James Howden and Co. developed what came to be called the ICI-Howden process, wherein a slurry of lime or chalk was circulated through a grid packed scrubber. Flue gas desulfurization using lime or limestone wet slurries is more art than science. In lime and limestone wet scrubbing of flue gases, the most important chemical property of SO2 to be exploited is the fact that SO2 is an acidic anhydride. The low solubility of calcium carbonate is one of the chief drawbacks against its use in wet scrubbing processes for SO2 removal. The reaction between SO2 and lime or limestone occurs in solution as reactions between ionized species.
