Internals of process column: Columns based on internal details are often called as either Plate Columns or Packed Columns. Plate Column: The lighter hydrocarbons vaporise and flow up through the holes in the tray plate, making contact with the liquids on that tray.
Internals of process column
Types of Trays
- Bubble Cap trays
- Valve trays
- Sieve trays
Bubble Cap Trays: Bubbling action effects contact. Vapour rises up through ‘risers’ into bubble cap, out through slots as bubbles into surrounding liquid on tray. Liquid flow over caps, outlet weir and downcomer to tray below.
Valve Trays: Commonly used valve trays are stamped out by big press and these trays come with small valves attached to them which allow vapour traffic.
Sieve Trays: Sieve trays are perforated flat plates. They are inexpensive for small diameter vessels but large diameter towers must have extensive supports for these trays. Sieve trays are used for heavy hydrocarbon fractionation.
All trays have foam on top of liquid. The height of the foam will vary with the process. Foam may rise a foot or more above the tray liquid. Liquid-gas contacting is made effective through the above trays by cross-flow or counter flow. In counter flow plates, liquid and gas utilise the same openings for flow, thus there are no downcomers.
Perforated plate with liquid cross flow (sieve plate) is the commonly specified tray. The two most commonly used types of tower viz. the trayed and packed arrangements. you can also refer what is distillation, absorption column here
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