Disk Donut Tray

Disk and donut trays are slightly sloped trays located inside a column in such a manner that the liquid and vapour are brought in to 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. It offer a higher capacity and lower pressure drop compared with conventional sieve and valve trays, The trade-off is a considerably lower contacting efficiency. having an extremely high open area, they are most suitable for dirty service and heavy fouling applications. Examples are heavy oil refining and petrochemical heat transfer services having a petroleum coke / high solids content.

Dual Flow Tray

 Dualflow trays are normally perforated with large diameter holes on a uniform pattern across the full cross section of the tower. They are supported by 360 degree tray support rings, since downcomers are not required. 

The perforations in the tray provide the dual purpose of vapor and liquid exchange. In a normal operating mode, liquid moves and splashes on top of the tray in a wavelike manner. Liquid will periodically flow 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 is of typical design without special features.