What is a baffle tray 5

[801217]

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

 

[katmar]

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.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[EmmanuelTop]

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.

http://antwrp.gsfc.nasa.gov/apod/astropix.html

 

[801217]

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!

 

[katmar]

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.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[801217]

Dear Katmar,
Thanks so much for your kind help.

 

[0707]

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

Luís marques

 

[801217]

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

 

[801217]

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!

 

[unclesyd]

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

http://www.lindahall.org/

 

[0707]

“Shed decks are essentially angle iron beams of various sizes from two to ten inches that are placed in rows across the column. They typically are at on 24 inch tray spacing. They may be set in overlapping rows or rotated 90 degrees from tray to tray. The open area on the tray is typically 50%. The positives of shed deck are that the fouling potential of the decks is almost zero because there are no stagnate zones and low residence time. Unfortunally, the efficiency of the tray almost matches the fouling potential, particularly if wide shed decks are utilized. Shed decks work well in fouling applications where their application is essentially for heat-transfer purposes.”

“Side-to-side trays are trays that allow the liquid to splash from side to side. The decks can be sloped. Fouling potential of this tray is low, as with efficiency”

For more information please go to

http://www.kolmetz.com/pdf/foulingpaperfinal.pdf

Best regards

Luis Marques

 

[801217]

Thanks 0707!

Much appreciate for your help!