Tray Towers

Refer to Figs.(4, 5).

  • Valve Trays: In valve trays, perforations are covered by liftable caps. Vapor flows lifts the caps, thus self creating a flow area for the passage of vapor. The lifting cap directs the vapor to flow horizontally into the liquid, thus providing better mixing than is possible in sieve trays.

  • Bubble Caps: A bubble cap tray has riser or chimney fitted over each hole, and a cap that covers the riser. The cap is mounted so that there is a space between riser and cap to allow the passage of vapor. Vapor rises through the riser and is directed downward by the cap, discharging through slots in the cap, and finally bubbling through the liquid on the tray.

  • In oversize columns, vapor pressure drops through the tray openings near the tray inlet may not be great enough to prevent liquid from passing through them. When this occurs on bubble cap trays, its is called dumping; on sieve trays it is called weeping.