Distillation Trays
Disk and donut trays are slightly sloped trays installed inside a column, designed to bring liquid and vapour into direct contact by forcing vapour through falling liquid. Liquid descends from one tray to the next either as a curtain of liquid raining down or as liquid rivulets passing through holes in the tray deck. Compared with conventional sieve and valve trays, they offer higher capacity and lower pressure drop — the trade-off is considerably lower contacting efficiency. With an extremely high open area, they are most suitable for dirty service and heavy fouling applications, such as heavy oil refining and petrochemical heat transfer services involving petroleum coke or high solids content.
Cartridge trays are suitable for small-diameter body flange columns, typically with an outer diameter (OD) less than 500 mm. Each cartridge can accommodate up to 5 trays. The trays themselves can be valve-type, sieve-type, or bubble cap designs, which are uniquely engineered to suit specific application requirements.
Dualflow trays are normally perforated with large-diameter holes arranged in a uniform pattern across the full cross-section of the tower. They are supported by 360-degree tray support rings, as downcomers are not required.
The perforations in the tray serve the dual purpose of vapor and liquid exchange. In normal operation, liquid moves and splashes on top of the tray in a wavelike manner. Liquid periodically flows through the perforations under the areas of liquid peaks, while vapor rises through holes in the valleys or liquid low points.
The dualflow tray depicted above features a typical design without special features.
