PP Plastic Tray Distributor

A tray-type liquid distributor is the device that takes the liquid entering a packed column and lays it down evenly over the whole top face of the packing. It is built as a shallow pan or tray with open tubes, called risers, rising from its floor. The incoming liquid ponds in the tray and leaves through small metering holes, and sometimes spray points, spaced across the floor so that every part of the bed below gets its fair share; the vapour coming up the column goes through the risers, which are capped so the liquid cannot fall into them. Why it matters is simple. Packing only works where liquid actually flows over it. If the liquid is poured in unevenly it will find the easy paths, running down the wall, or cutting channels through the bed, and large parts of the packing stay dry and do no work, so the column separates poorly. An even distributor keeps the whole bed wetted, which is why it is one of the most important internals in a packed tower.

The tray does two things at once, keeping the liquid and the vapour on separate paths. The liquid path is the tray floor: liquid fed onto the tray builds a shallow, even pool, and drains out through the pattern of metering holes and spray holes drilled in the floor, so it leaves as many small, evenly spaced streams onto the packing. The head of liquid in the pan sets the flow through the holes, so as long as there is a pool the distribution stays even. The vapour path is the risers, the open tubes standing proud of the floor. Gas rising up the column passes up through them, above the liquid level, and each riser wears a small cap, shaped to shed liquid, so droplets and the pooled liquid cannot drop down inside and short-circuit the gas opening. The pan is sealed at its joints, a segmented flange seal holds leakage under 1 percent in a pressure test, so all the liquid goes where the holes send it. Detachable trays bolt together for towers with tight access; welded trays are used where a solid one-piece plate suits a larger column.

The tray is normally moulded in polypropylene, which is light, a little under one gram per cubic centimetre, so far lighter than a metal tray, flexible enough to survive being flexed a million times without cracking, and resistant to corrosion and to heat. For the most aggressive liquids, acids or strong solvents, it is made instead in PTFE or PVC, which stand up to chemistry that would attack PP. Two performance numbers matter for a distributor. The turndown, or flow range, is about ten to one, meaning the same tray distributes evenly whether the column is running near its design rate or throttled well below it, which is useful when the plant load swings. And the leakage is held under 1 percent in a pressure test, thanks to sealed, segmented joints, so almost none of the liquid bypasses the distribution holes. It is made to ISO-9001. Tell us the liquid, the flow range and the tower and we will size the tray and pick the plastic.

A PP tray distributor is used at the top of the packing, and at redistribution points partway down a tall bed, in packed columns that run corrosive or simply cool enough for plastic. It goes into distillation columns, absorbers, scrubbers and stripping towers, and it works across the pressure range, from atmospheric service down to vacuum. It is a good match for awkward liquids too: high flow rates, and viscous or slurry-like fluids such as some petrochemical streams, which need generously sized holes to distribute without blocking. In every case its purpose is the same, to feed the liquid onto the packing evenly so the bed is fully wetted and the column separates as designed, in a light, corrosion-resistant plastic body. Send us the service, the liquid and the column size and we will design the distributor.