Monthly Archives for March 2011

Inlet Weirs

Most trays have outlet weirs devoted to maintaining the downcomer seal. But some trays have inlet weirs too, or inlet weirs, but no outlet weirs. A sketch of an inlet weir is shown in Fig. 8.2. Note the horizontal distance … Continue reading

29. March 2011 by Jack
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Improper Downcomer Clearance

The bottom edge of the downcomer from the tray above should be 0.25 to 0.5 in below the top edge of the weir of the tray below. This is called a positive downcomer seal. Without a positive downcomer seal, vapor … Continue reading

29. March 2011 by Jack
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Loss of Downcomer Seal Due to Leaks

The vertical edges to the downcomers are bolted to bars welded to the vessel wall. These are called, “downcomer bolting bars.” Gaskets are often used to tightly seal the edge of the tray downcomer to these bars. If the bolts … Continue reading

29. March 2011 by Jack
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Tray Deck Levelness

For smaller diameter towers a visual check of tray deck levelness is sufficient. For two-pass trays, a small diameter tower is less than 8 ft. For single-pass trays, a diameter of less than 6 ft is small.For towers of 10 … Continue reading

29. March 2011 by Jack
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Kettle Reboilers

Reboilers are sometimes inserted into the bottom of a tower. These are called “stab-in” reboilers. It is not a terribly good idea, because it makes it more difficult to fix a leaking or fouled reboiler without opening the tower itself. … Continue reading

29. March 2011 by Jack
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Forced-Circulation Reboilers

Figure 7.6 shows a once-through forced-circulation reboiler. Such a reboiler differs from a thermosyphon reboiler in that it has a pump to force circulation, rather than relying on natural or thermosyphon circulation. This extra pump seems rather wasteful—and it is. … Continue reading

29. March 2011 by Jack
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Excessive Thermosyphon Circulation

In a once-through reboiler, the liquid flow coming out of the reboiler is limited to the bottoms product. In a circulating reboiler, the liquid flow coming out of the reboiler can be extremely high. If the reboiler return nozzle is … Continue reading

29. March 2011 by Jack
Categories: Reboiler | Tags: , | Leave a comment