Trough Liquid Distributor design, manufacture, shipment and
installation
1. Trough liquid distributor introduction,
Liquid distributor is the most important column internal from a
process point of view. It is required to distribute liquid
uniformly at the top of packing tower. Meanwhile a liquid
distributor must have sufficient gas passage area to avoid high
pressure drop or liquid entrainment.
2. Choice of liquid distributor:
Column Diameter mm | Specific liquid load M3/m2*h | System fouling tendency | Turndown ratio | Suitable type of liquid distributor |
| 250 - 900 | 0.75 - 5 | Low - medium | ＜10:1 | Trough type liquid distributor with sump Deck type liquid distributor with orifices on drip tubes |
| 5 - 30 | Low - medium | 2:1 | Pan type liquid distributor Trough type liquid distributor with sump |
| ＞30 | Low - medium | 2:1 | Pan type liquid distributor Trough type liquid distributor with sump Deck type liquid distributor |
| ＞900 | 0.75 - 5 | Low - medium | ＜10:1 | Trough type liquid distributor with parting box Deck type liquid distributor with orifices on drip tubes |
| 5 - 30 | Low - medium | 2:1 | Trough type liquid distributor with sump Trough type liquid distributor with parting box Deck type liquid distributor |
| ＞30 | Low - medium | 2:1 | Deck type liquid distributor Trough type liquid distributor with sump |
3. How to choose liquid distributor?
When we need to select a liquid distributor, we need to consider
the tower diameter, flow rate, turndown ratio, available height (in
case of revamp) and fouling resistance.
Weir type gravity distributor:
Generally speaking, the weir type gravity distributor is one of the
least troublesome distributors. It has excellent trundown
capability and can handle large liquid load. However it can usually
provide only a limited number of drip points (minimum 30 number of
weirs per m2). It is also extremely sensitive to levelness and
liquid surface agitation.
Orifice type gravity distributor:
Usually it shows as pan type, deck type or tunnel (trough) type. An
orifice pan distributor consists of a pan. There are circular or
rectangular risers for vapor flow and perforation for liquid flow
in the pan.
Orifice trough type distributors consist of parallel troughs with
perforated holes in the bottom for liquid flow. Vapor rises in the
space between the troughs. The troughs are often interconnected by
cross channels (called as parting box), which help equalize the
liquid level in different troughs. This trough type liquid
distributors provide more open area for vapor flow and is easier to
support.
Orifice type distributor can be designed to have a large number of
drip points to provide superior liquid distribution, though it may
suffer from corrosion and plugging. Orifices are sized to maintain
a minimum liquid head at desired turndown conditions & to avoid
distributor overflow during turn up condition. Very small orifice
diameters (<4mm) are avoided to prevent fouling.
4. Liquid distributors classification:
Usually there are pressure type liquid distributors and gravity
type liquid distributors.
Pressure type liquid distributor:
It provides more open area for vapor flow. Often it is less
expensive, lighter, less robust and requires smaller lead up piping
than gravity type liquid distributor. On the other hand, it
requires high operating cost, susceptibility to plugging, corrosion
and a relatively inferior quality. One example of pressure liquid
distributors is pipe arm and spray type liquid distributor.
5. Trough liquid distributor production
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