Wet flue gas cleaning (wet scrubbing)
Scrubbers are used in wet flue gas cleaning for cleaning the flue gas. In the scrubbing zone, the pollutants contained in the flue gas are separated through an intensive contact with the scrubbing water by means of physical or chemical absorption.
In the first stage of wet scrubbing, primarily HCl, HF, mercury compounds, dust, heavy metals bound in particles and gaseous heavy metals are absorbed in the acid scrubbing water. In the second stage, primarily SO2 is absorbed in a suspension of lime hydrate or sodium hydroxide solution (NaOH).
Wet flue gas cleaning facilities are often completed by a preceding stage for dust separation upstream of the scrubber and a downstream super-fine cleaning stage for organic compounds and heavy metals.
Diagram of simple, waste-water free wet scrubbing: