What is difference between bubble cap tray and sieve tray?
Bubble-cap trays have a positive liquid seal and can therefore operate efficiently at very low vapour rates. Sieve trays rely on the flow of vapours through the holes to hold the liquid on the tray, thus cannot operate at very low vapour rates. Sieve trays are the easiest to clean.
What is bubble cap distillation column?
A bubble cap tray has riser or chimney fitted over each hole, and a cap that covers the riser. Vapour rises through the chimney and is directed downward by the cap, finally discharging through slots in the cap, and finally bubbling through the liquid on the tray.
What are bubble caps used for?
Vapour rises through the chimney, and the cap helps to direct it downward, discharging the vapours through the slots in it. Bubble caps have a high turn-down ratio and are commonly used for low liquid loads. They offer high performance when operated in dynamic balance and optimum conditions.
How many types of distillation columns are there?
two
There are two main categories of distillation columns, batch and continuous.
What is weeping in distillation column?
what is weeping in distillation? Weeping is when liquid flows downward through the holes in a distillation tray. If the vapor rate is too low the liquid may be able to drop to the next stage through the holes, resulting in less than optimal vapor/liquid contact (and therefore less than optimal separation).
How does sieve tray work?
Sieve trays are the least expensive tray option. In sieve trays, vapor flowing up through the tower contacts the liquid by passing through small perforations in the tray floor (Figure 6.7b). Sieve trays rely on vapor velocity to exclude liquid from falling through the perforations in the tray floor.
What is sieve tray distillation column?
Sieve Trays The “Sieve tray” is a perforated plate type tray, with holes punched into the deck-plate that typically measure from 3/16” up through 1” in diameter. Typically, a standard hole size can measure 0.5” OD. Vapor comes out of the holes which in turn, keeps the liquid from weeping through.
What is sieve tray?
The sieve tray is a flat perforated plate with no moving parts. Vapor rises from the holes/ perforations to the tray above, cross-current to the liquid flow. The vapor energy keeps the liquid from flowing down through the holes. Smaller sieves reduce weeping whereas larger sieves are employed in fouling services.
How can we reduce weeping in distillation column?
If the reboiler produces low amount of vapour and send into the column, it will cause this type of problems. If we maintain the Vapour flow rate in constant level, we can overcome this problem . Otherwise we will go for the bubble cap contractor or valve tray to avoid weeping.