An impingement plate scrubber is a vertical chamber with plates mounted horizontally inside a
hollow shell. Impingement plate scrubbers operate as countercurrent 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. Figure 1 shows common plate designs used in impingement plate scrubbers.
The simplest impingement plate is the sieve plate, which has round perforations. In this type of
scrubber, the scrubbing liquid flows over the plates and the gas flows up through the holes. The gas
velocity prevents the liquid from flowing down through the perforations. Gas-liquid-particle contact is achieved within the froth generated by the gas passing through the liquid layer. Complex plates, such as
bubble cap or baffle plates, introduce an additional means of collecting PM. The bubble caps and
baffles placed above the plate perforations force the gas to turn before escaping the layer of liquid.
While the gas turns to avoid the obstacles, most PM cannot and is collected by impaction on the caps
or baffles. Bubble caps and the like also prevent liquid from flowing down the perforations if the gas
flow is reduced.
In all types of impingement plate scrubbers, the scrubbing liquid flows across each plate and
down the inside of the tower onto the plate below. After the bottom plate, the liquid and collected PM
flow out of the bottom of the tower. A typical impingement plate scrubber is shown in Figure 2
Impingement plate scrubbers are usually designed to provide operator access to each tray, making
them relatively easy to clean and maintain. Consequently, impingement plate scrubbers are more
suitable for PM collection than packed-bed scrubbers. Particles greater than 1 :m in diameter can be
collected effectively by impingement plate scrubbers, but many particles <1 μm will penetrate these
devices.
hollow shell. Impingement plate scrubbers operate as countercurrent 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. Figure 1 shows common plate designs used in impingement plate scrubbers.
Common plate design for Impingement Plate Scrubbers
The simplest impingement plate is the sieve plate, which has round perforations. In this type of
scrubber, the scrubbing liquid flows over the plates and the gas flows up through the holes. The gas
velocity prevents the liquid from flowing down through the perforations. Gas-liquid-particle contact is achieved within the froth generated by the gas passing through the liquid layer. Complex plates, such as
bubble cap or baffle plates, introduce an additional means of collecting PM. The bubble caps and
baffles placed above the plate perforations force the gas to turn before escaping the layer of liquid.
While the gas turns to avoid the obstacles, most PM cannot and is collected by impaction on the caps
or baffles. Bubble caps and the like also prevent liquid from flowing down the perforations if the gas
flow is reduced.
In all types of impingement plate scrubbers, the scrubbing liquid flows across each plate and
down the inside of the tower onto the plate below. After the bottom plate, the liquid and collected PM
flow out of the bottom of the tower. A typical impingement plate scrubber is shown in Figure 2
Impingement plate scrubbers are usually designed to provide operator access to each tray, making
them relatively easy to clean and maintain. Consequently, impingement plate scrubbers are more
suitable for PM collection than packed-bed scrubbers. Particles greater than 1 :m in diameter can be
collected effectively by impingement plate scrubbers, but many particles <1 μm will penetrate these
devices.
Schematic diagram of a plate tower scrubber
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