Tray or Plate Column

The tray or plate column has down comers for transporting a liquid between neighboring trays. The liquid transport happens in each down comer through a plurality of discharge apertures onto a loaded tray. Liquid flows out of the discharge apertures in the form of jets that merge into a regionally different flow field on striking the loaded tray. The flow field has transverse apparatus of the flow speed with respect to a longitudinal main flow direction. Direction elements are set beneath the discharge apertures and at spacing from the loaded tray which each guide the impulse of liquid analogous to the divergent flow field.

The guide elements

The direction elements donate to forming the transverse speed components such that the longitudinal component of the flow speed has a largely stable profile in each plane perpendicular to the main flow direction. The discharge apertures are preferably made in different sizes in a graduated fashion to be smaller in a central area than in neighboring flank regions.

Conduit known as riser

And a still has a boiler at one end and a condenser at the other end. Union of these two together is a conduit to transport fluids from one end to the other for further processing. This conduit is knows as a riser in a pot still and tray or plate column in a fractionating still. In pot stills, the riser and the lyne arm serve to transport vapors out of the boilers and into the next stage which is generally a product condenser. Sometimes the next stage is an intermediary stage called as a thumper which is actually a second plate that affords another distillation.

Composite columns

But in a fractioning still, the tray or plate column provides a more complex purpose. It transports vapors but also transports liquids and separates and enriches the substances many times over. The contact at each plate is equivalent to a re-distillation. This process is referred to by several names in the industry; namely rectification, fractionation and fractional distillation. The flow of liquid and vapor through a tray column is composite. Liquid falls through the down comers by gravity from one tray to the one beneath it.

A weir on the tray makes sure that there is all the time some liquid on the tray and is planned such that the holdup is at a proper height, for instance such that the bubble caps are covered by liquid. The vapor flows up the column and is required to move through the liquid through the openings on each tray.

Questions:

• What is tray column?
• State the role of tray or plate column.