Category Archives for Tray

High Capacity Trays

All vendors now market a high capacity tray. These trays have a 5 to 15 percent capacity advantage over conventional trays. Basically, the idea behind these high capacity trays is the same. The area underneath the downcomer is converted to … Continue reading

24. January 2011 by Jack
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Distillation Tower Turndown

The problem we have been discussing—loss of tray efficiency due to low vapor velocity—is commonly called turndown. It is the opposite of flooding, which is indicated by loss of tray efficiency at high vapor velocity. To discriminate between flooding and … Continue reading

24. January 2011 by Jack
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Bubble-Cap Trays

The first continuous distillation tower built was the “patent still” used in Britain to produce Scotch whiskey, in 1835. The patent still is to this day employed to make apple brandy in southern England. The original still, and the one … Continue reading

24. January 2011 by Jack
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Causes of Tray Inefficiency : Loss of Downcomer Seal

We stated that the top edge of the outlet weir is maintained about 0.5 in above the bottom edge of the inlet downcomer to prevent vapor from flowing up the downcomer. This is called a 0.5-in positive downcomer seal. But … Continue reading

24. January 2011 by Jack
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Causes of Tray Inefficiency : Out-of-Level Trays

When trays weep, efficiency may not be significantly reduced. After all, the dripping liquid will still come into good contact with the upflowing vapor. But this statement would be valid only if the tray decks were absolutely level. And in … Continue reading

24. January 2011 by Jack
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How Trays Work

A distillation tray works efficiently when the vapor and liquid come into intimate contact on the tray deck. To this end, the liquid should flow evenly across the tray deck. The vapor should bubble up evenly through the perforations on … Continue reading

24. January 2011 by Jack
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Carbon Steel Trays

One of the most frequent causes of flooding is the use of carbon steel trays. Especially when the valve caps are also carbon steel, the valves have a tendency to stick in a partially closed position. This raises the pressure … Continue reading

24. January 2011 by Jack
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Trays Jet Flood

Figure 3.8 is a realistic picture of what we would see if our towers were made of glass. In addition to the downcomers and tray decks containing froth or foam, there is a quantity of spray, or entrained liquid, lifted … Continue reading

24. January 2011 by Jack
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Total Height of Liquid in Downcomer

To summarize, the total height of clear liquid in the downcomer is the sum of four factors: • Liquid escape velocity from the downcomer onto the tray below. • Weir height. • Crest height of liquid overflowing the outlet weir. … Continue reading

24. January 2011 by Jack
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Tray Vapor-Flow Pressure Drop

We have yet to discuss the most important factor in determining the height of liquid in the downcomer. This is the pressure drop of the vapor flowing through the tray deck. Typically, 50 percent of the level in the downcomer … Continue reading

24. January 2011 by Jack
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