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[conan_kaya]

I am now having my attachment in a refining company.

I was posted this question by a senior engineer.

For a tray in the distillation column, is the height of the weir important.

There is generally 2 purposes for the weir. One of them is to maintain a certain liquid level on the tray. What is the second one?

Also, the senior engineer did mention that the height of the weir and the distance between the end of the downcomer(from the above tray) and that of the end of the tray are inter-related and play an important and fundamental role in the designing and working of a distillation column. Can someone advice me on what is the importance?

THank you!

[Zauberberg]

Conan,

All the answers can be easily found in any distillation textbook. I bet you can find them just by Google-ing for a few minutes.

The most important purpose of outlet weir is to provide liquid seal, i.e. to ensure that upflowing vapors cannot pass up the downcomer and push the downflowing liquid onto tray above and cause flooding. As long as the height of outlet weir is higher than the downcomer clearance (the distance between the bottom of downcomer and the tray below), there will be a positive liquid seal that prevents reverse flow of liquid inside the tower.

Some special applications (e.g. columns that operate at extremely high liquid rates all the time) can have outlet weir smaller than the downcomer clearance, since high liquid flow itself provides liquid seal (so called "Dynamic seal").

Best regards,