Packed-bed scrubbers consist of a chamber containing layers of variously-shaped packing
material, such as raschig rings, spiral rings, and berl saddles, that provide a large surface area for liquidparticle contact. These and other types of packings are illustrated in Figure 1 The packing is
held in place by wire mesh retainers and supported by a plate near the bottom of the scrubber.
Scrubbing liquid is evenly introduced above the packing and flows down through the bed. The liquid
coats the packing and establishes a thin film. In vertical designs, the gas stream flows up the chamber
(countercurrent to the liquid). Some packed beds are designed horizontally for gas flow across the
packing (crosscurrent).
In packed-bed scrubbers, the gas stream is forced to follow a circuitous path through the
packing, on which much of the PM impacts. The liquid on the packing collects the PM and flows down the chamber towards the drain at the bottom of the tower. A mist eliminator (also called a "de-mister") is typically positioned above/after the packing and scrubbing liquid supply. Any scrubbing liquid and wetted PM entrained in the exiting gas stream will be removed by the mist eliminator and returned to drain through the packed bed. A typical packed-bed scrubber is illustrated in Figure 2
In a packed-bed scrubber, high PM concentrations can clog the bed, hence, the limitation of
these devices to streams with relatively low dust loadings. Plugging is a serious problem for packedbed scrubbers because the packing is more difficult to access and clean than other scrubber designs. Mobile-bed scrubbers are available that are packed with low-density plastic spheres that are free to move within the packed bed. These scrubbers are less susceptible to plugging because of the
increased movement of the packing material. In general, packed-bed scrubbers are more suitable for
gas scrubbing than particulate scrubbing because of the high maintenance requirements for control of
PM
material, such as raschig rings, spiral rings, and berl saddles, that provide a large surface area for liquidparticle contact. These and other types of packings are illustrated in Figure 1 The packing is
held in place by wire mesh retainers and supported by a plate near the bottom of the scrubber.
Scrubbing liquid is evenly introduced above the packing and flows down through the bed. The liquid
coats the packing and establishes a thin film. In vertical designs, the gas stream flows up the chamber
(countercurrent to the liquid). Some packed beds are designed horizontally for gas flow across the
packing (crosscurrent).
Typical packing materials for packed bed scrubbers
In packed-bed scrubbers, the gas stream is forced to follow a circuitous path through the
packing, on which much of the PM impacts. The liquid on the packing collects the PM and flows down the chamber towards the drain at the bottom of the tower. A mist eliminator (also called a "de-mister") is typically positioned above/after the packing and scrubbing liquid supply. Any scrubbing liquid and wetted PM entrained in the exiting gas stream will be removed by the mist eliminator and returned to drain through the packed bed. A typical packed-bed scrubber is illustrated in Figure 2
Schematic Diagram for packed tower scrubber
In a packed-bed scrubber, high PM concentrations can clog the bed, hence, the limitation of
these devices to streams with relatively low dust loadings. Plugging is a serious problem for packedbed scrubbers because the packing is more difficult to access and clean than other scrubber designs. Mobile-bed scrubbers are available that are packed with low-density plastic spheres that are free to move within the packed bed. These scrubbers are less susceptible to plugging because of the
increased movement of the packing material. In general, packed-bed scrubbers are more suitable for
gas scrubbing than particulate scrubbing because of the high maintenance requirements for control of
PM
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