Impingement-plate-tower scrubbers

Impingement-plate-tower scrubbers have a number of horizontal plates or trays mounted in a tower. The gas stream is made to flow upwards, countercurrent against a downward flow of scrubbing liquid against which the desired aerosol particles and/or droplets are made to impact. The scrubbing liquid is usually an absorbent, or reactive, or solvent liquid. 

These scrubbers have had limited use as part of flue gas desulfurization (FGD) systems, but the scrubbing solution flow rate must be carefully controlled to avoid flooding. When absorption is used for VOC control, packed towers are usually more cost effective than impingement plate towers (discussed later). 

PM Impingement-plate tower collection efficiencies range from 50 to 99 percent, depending upon the application. This type of scrubber relies almost exclusively on inertial impaction for PM collection. Therefore, collection efficiency decreases as particle size decreases. Short residence times will also lower scrubber efficiency for small particles. Collection efficiencies for small particles (< 1 fim in aerodynamic diameter) are low for these scrubbers hence, they are not recommended for fine PM control. 

PM Control - An impingement-plate scrubber is a vertical chamber with plates mounted horizontally inside a hollow shell. Impingement-plate scrubbers operate as eountercurrent PM collection devices. The scrubbing liquid flows down the tower while the gas stream flows upward. Contact between the liquid and the particle-laden gas occurs on the plates. The plates are equipped with openings that allow the gas to pass through. Some plates are perforated or slotted, while more complex plates have valve-like openings. 

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