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Changing Feed Tray Location In A Distillation Column

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#1 titim


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Posted 28 March 2018 - 08:47 AM

Hi every one, my question is:
if my feed is becoming lighter or heavier, what i must change of the Feed Tray Location In A Distillation Column (if it's my option)
If the feed become lighter, must i change to the Up or Down tray?
If the feed become heavier must i change to the Up or Down tray?
Best regards.


#2 Bobby Strain

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Posted 28 March 2018 - 11:05 AM

If you have a process simulator, use it. If you don't have one, get one. There is a least one good one that is free.



#3 latexman


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Posted 28 March 2018 - 12:12 PM



Open the text book to McCabe-Theile diagram/method.  The answer is in there.  This is a question every graduate ChE should have the answer on the tip of their tongue, if the feed concentration changes enough.


Are you a student?

#4 Pilesar


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Posted 28 March 2018 - 12:49 PM

A simple way to look at optimal feed location that usually works is to put the feed where it will best match the composition inside the column. I think of it as at any point in the column the trays have worked hard to purify the product streams. I don't want to add feed that is 'dirtier' than the tray would normally see if I can help it. That way the trays do not have to do 'extra work' to again separate components that had already been separated. The purpose of the column matters -- for example there may be no feed location change at all if your column is a stripper only. A steady state process simulator makes choosing feed location much easier with automated case studies or built in optimizer. The 'simple way' above is a good way to estimate but the simulator can fine-tune the optimal location.

#5 Pilesar


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Posted 28 March 2018 - 12:58 PM

If your question is about a real-life distillation column, we do not have enough information to answer whether the feed tray should move higher or lower. This is because in real-life columns, the current feed tray may not be at the optimal location! The correct answer is 'move the feed tray to the optimal location for the feed'. This is where the simulator earns its cost and helps keep the process engineer employed.

#6 Nikolai T

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Posted 28 March 2018 - 10:12 PM



You can consult Distillation Design Chaper 2 Henry Z. Kister.



#7 rdcrags


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Posted 04 April 2018 - 08:04 PM

Simulate the operation as suggested. The feed may already be in the best location for the new operation, which would mean it wasn't in the old operation.

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