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What is a baffle tray [Copy URL]

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Post time 2012-10-17 11:30:58 |Show all posts

Dear all,
Is there any one familiar with the tower tray? What is the baffle tray? And what is the difference between baffle tray and shower deck tray?

Is there anyone could explain to me? I appreciate so much



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Post time 2012-10-17 11:31:01 |Show all posts

In my experience a baffle tray and a shower deck tray are the same thing.  I have come across 2 types of baffle trays. One has segmental cutouts like a heat exchanger baffle, resulting in a zig-zag flowpath down the column. The other is the "disk and donut" type where disks (smaller than the column ID) are alternated with annular rings (which are fixed to the shell inner wall).

It is unusual to find these trays used in distillation or absorption duties. They are apparently sometimes employed as the stripper column in a fermentation ethanol plant where there are about 10% solids in the liquor.

The more common application of these trays (AFAIK) is in direct contact condensers (aka barometric condensers). But even in this duty they are rare and "rain trays" are more commonly used.

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Post time 2012-10-17 11:31:02 |Show all posts


Baffle trays or so-called shed decks are usually employed in wash section of FCC main fractionator and catalyst strippers. The only advantage of these trays is they are impossible to plug while still providing the basic purpose of washing flash zone vapors from entrained liquid, and also providing smooth flow of fluidized catalyst particles. It is very roboust and not so efficient design, nowadays almost completely abandoned except in few specific applications.

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Post time 2012-10-17 11:31:04 |Show all posts

Thanks for all. Another question is that what is the common size of the hole on the tray? Area percent of the hole? And what is the usually cutouts persent? Do you have any experience in designing this kind of tray?

Thanks again for your kind help!



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Post time 2012-10-17 11:31:07 |Show all posts

I found a design reference deep in my filing system that confirms that baffle trays are also called "splash decks" or "shower decks". The article gives sizing criteria like pressure drop correlations and HETP estimates. Ref is J.R.Fair, Hydrocarbon Processing, May 1993, pgs 75-80.

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Post time 2012-10-17 11:31:09 |Show all posts

Dear Katmar,
Thanks so much for your kind help.



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Post time 2012-10-17 11:31:10 |Show all posts


Baffle trays and disc & donut trays are particularly
well suited to heavy fouling systems due to their extremely
high open area. Typical applications include heavy oil
refining and petrochemical heat transfer services having a
high solid and/or petroleum coke content.

Baffle trays are trays of low fouling potential, with low
efficiency. They have open areas approaching 50%
where a high efficiency tray will have an open area of less
than 15%.

Three major types of baffle trays are

1. Shed Decks
2. Side to Side Trays
3. Disk and Donut

Regards

Lu

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Post time 2012-10-17 11:31:14 |Show all posts

thanks Katmar,
Could you tell me where I could find that article?
I have searched by google.But no matching result.



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Post time 2012-10-17 11:31:15 |Show all posts

Thanks 0707!
Could you tell me what is the difference for the side-to-side pan and shed deck? Is it because that shed deck has some holes on the deck? If so, what is the common size of the hole?

Thanks a lot!



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Post time 2012-10-17 11:31:17 |Show all posts

The article referenced by Katmar is available for a small fee from the Linda Hall Library.



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