Liquid Distributors and Re-distributors
Liquid distributors for scrubber applications fall into two main categories, Gravity type and Spray type distributors. Gravity type Liquid distributors rely on gravity to provide the necessary energy to disperse the liquid through the Liquid distributors and eventually across the packing surface. Gravity distributors are available in either Orifice or Weir type. One benefit of the Gravity type distributor is the low turn-down ratio. These types of distributors function equally well at both low and high liquid flow rates and do not require high influent liquid pressure. All of the gravity type distributors are fabricated in sections to allow for ease of installation through the vessel manways. Each can be made from a variety of plastics, fiberglass, or exotic metals. Gravity type distributors should not be used if the recirculation liquid can solidify at ambient conditions.
The Orifice type Liquid distributors utilizes a full cross-sectional plate with numerous holes drilled through the bottom to allow the liquid to drain down on to the packing surface. The plate has raised edges, to prevent the liquid from running down the wall of the vessel. The plate is also equipped with vertical pipes to allow the treated air to pass through for discharge. The orifice type distributor is best suited for small tower applications due to the limitations of free area for the process air to pass through.
The other gravity type liquid distributor is the Weir type. Weir type Liquid distributors are available in two basic configurations: Pipe and Trough styles. The Pipe style is constructed of a main pipe, which drains to numerous lateral pipes, which distribute the liquid across the packing. The Trough type works basically the same as the pipe type except it utilizes troughs instead of pipe. The trough type allows for greater flow volumes and can be used with larger vessels. Both the Trough and Pipe type have large free area for air passage.
Liquid Redistributors can be used as well if chemical consumption is a concern a redistributor collects the down coming liquid from the bed above and distributes it evenly over the packing.
There are four basic advantages to using a redistributor:
- higher liquid handling capacity,
- elimination of wall streaming,
- non-fouling design,
- constant percentage of free space, regardless of tower diameter.
Redistributors can be equipped with wall wipers to collect the liquid clinging to the tower walls.
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