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. The cap is mounted so that there is a space between riser and cap to allow the passage of vapour.
What is the function of bubble cap?
A bubble cap device in a glycol contactor consists of a cap and a riser. It helps to promote the contact between the glycol liquid and the natural gas. The cap is fitted over a vent, and the riser is used to cover the bubble cap tray.
What is the purpose of bubble caps in fractional distillation?
Each perforation is fitted with a bubble cap. Very hot, vaporized crude oil is pumped into the bottom of the column and rises up through the perforations. The bubble cap forces the oil vapor to bubble through liquid on the tray. This causes the vapor to cool as it flows upward and to condense into liquids.
Why bubble cap tray is used?
Bubble cap trays are generally used when minimal leakage is allowed. They are also used for low liquid loads and have a very high turndown ratio.
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.
Why packing is used in distillation column?
Packing material can be used instead of trays to improve separation in distillation columns. Packing offers the advantage of a lower pressure drop across the column (when compared to plates or trays), which is beneficial while operating under vacuum.
Why trays are used in distillation column?
The trays have openings to allow vapor to flow upward through the column, as well as conduits (downcomers) to allow condensed liquid to flow downward (Figure). The tray is designed to promote intimate contact between the upward-moving vapor and downward-moving liquid.
What are the types of packing in distillation column?
Two main types of packing in a packed column are random packing and structured packing.
What is bubble cap tray?
Bubble cap tray is a flat perforated plate with risers (like pipes) around the perforations, and caps in the form of inverted cups over the risers. The caps are usually equipped with slots or holes through which vapor comes out.
Why are bubble cap trays more efficient than valve trays?
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.
What is Weir in distillation column?
Weirs. The function of a weir is to maintain a desired liquid level on the tray. Typical weir height is between 2 – 4 inches. Low weirs are frequently used in low pressure or vacuum columns. Notched (rectangular or V-shaped) weirs are commonly used for low liquid loads.
What is Downcomer in distillation column?
Downcomer: A device to direct the liquid from a distillation column at a location above the bottom tray and below the top tray.
What is baffle tray?
Baffle trays are unperforated trays with large “downcomer” areas for use in low-efficiency and highly fouling services which require a lower degree of vapor/liquid contact when compred to other conventional trays.
Each tray in a distillation column is designed to promote contact between the vapor and liquid on the stage, so there is mass and heat transfer. Ideally, the vapor and liquid leaving the stage are in equilibrium.
What is the difference between packed column and tray column?
Plate Column or Tray Tower Plate column is used for relatively large diameter & a large number of stages. A packed column is suitable for low-capacity operation. Plate column can handle a wider range of gas and liquid flow rates.
What is the purpose of weir in tray tower?
Weir: The function of a weir is to maintain a desired liquid level on the tray. Typical weir height is between 2 to 4 inch. Low weirs are frequently used in low pressure column.
What causes flooding in a distillation column?
Flooding is triggered by increasing the reboiler heat duty. Increasing the reboiler heat duty causes more vapor to be boiled up, which increases the vapor flow up the column. Eventually, the increasing vapor flow rate exceeds a critical threshold and triggers flooding.
What is the purpose of a Downcomer?
The primary function of downcomers on trays is to facilitate countercurrent liquid flow down the column with vapor flowing up through the tray openings on sieve and valve trays.