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Estimating Packed Tower Diameter/height

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#1 zunisim


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Posted 12 July 2008 - 11:36 AM

Hello all,

I'm a senior student for Chem E, at the Technion, Israel.
I need to design a packed tower (by hand and by Unisin)
How do i estimate the column diameter/height?
I found the theoretical number of trays the volumetric flow rate.
In order to proceed i need the column diameter so i can estimate the gas velocity (needed for the HETP etc.).
I tried to use the diameter calculated by Unisim for a sieve/valve tray column but then i noticed that the simulation gives me a different diamter for a packed column so that made me believe that there must be a way to calculate the diameter without estimating the tray column first.


Gil Taieb

#2 John Kervin

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Posted 12 July 2008 - 01:08 PM

Hello.I'm a senior student at University of the Philippines at Los Banos.Im taking Unit Operations I course this semester. Hope that my knowledge on packed towers will enlighten you.


I'm not well versed in estimating the diameter of the packed tower but as far as i remember from my class last week. Follow this steps:

1.Find our Bible. (Perry's 7th ed) Locate Equation 14-150 .
2. Compute for the F LG
3. Also find the value of the Capacitor factor ( Cs )
4.Find the actual CS. (use as the efficiency of the capacitor)
5.Find the Superficial gas velocity Ut from Eq. 14-150
6. Compute for the area.
from here on you can find the diameter of the packed column.

with regards to your problem on estimation of packed tower's height i think it would be hard for me to explain it to you by words, better to consult others for clearer presentation.Or try hitting the books. It help you alot.

Generous Deed: I have a soft copy of Perry's, if you want it. I can give it to you.

#3 Art Montemayor

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Posted 12 July 2008 - 05:17 PM


Unless you have the written permission from the owner's of the copyright for Perry's ChE Handbook (which I strongly doubt), then you have no legal right to be "generous" with other people's intellectual property. If you make a "soft" copy of the Handbook (scan it into an Adobe file) and distribtute it without legal permission you are a software pirate and will be prosecuted, if caught. Besides that, no self-respecting professional Chemical Engineer is going to ever trust you or offer you a legal, honest job in the future - should they ever find out what you did. Besides all of the above, I simply won't let you (or others) turn our Forums into a software Pirating brokerage spot.

Take these words of sage advice from someone who knows how professional chemical engineers make a legal, honest living. If you break the law, you must be prepared to pay the consequences.

#4 zunisim


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Posted 13 July 2008 - 03:04 AM

Hello again,

First i want to thank you John. I have checked the equation you talked about (14-150) and the rest of the chapter refering to packed column estimation but I still don`t have an answer.
For using all the equations and correlations i need the superficial velocity of the gas which i don`t have (because i still haven`t found the column diameter).
so my question remains the same:
"How do i estimate the column diameter?"


#5 John Kervin

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Posted 13 July 2008 - 03:36 AM


Im sorry. Im not aware of that matter. I thought that the soft copy of the Perry was part of the Book itself. (Honestly)

Thank you for reminding me the hard truth about intellectual property rights.
It enlightens me very much.

Again, my greatest apology.

#6 katmar


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Posted 13 July 2008 - 04:01 AM


#7 Root


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Posted 13 July 2008 - 06:38 AM


You are doing very good and parctical problem, to find out the Dia meter of column is, Ac=Q/V
Ac: Crossectional Area
Q:Flow m^3/Sec
V:Superficial Velocity
this is very easy to calculate the Hight of absorption column, Read Richardson and Culson V3, hope you will find enough help.
Good luck

#8 zunisim


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Posted 13 July 2008 - 11:46 AM


Thank you Toor but your solution doesn`t help me.
I`m looking for the diameter, this means i don`t have the cross section nor the Superficial Velocity.
If you look at it mathematicly this equation Ac=Q/V has two degrees of freedom.


#9 Art Montemayor

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Posted 13 July 2008 - 12:33 PM


If you haven't followed up on Katmar's post, I highly recommend that you do so. Katmar has given you the direct, specific answer to your basic query: use the Sherwood relationship as found here in this website - for free download.

I would follow the above recommendation by some additional advice: try to follow whatever suggestions, hints, help, or advice that you may be successful in obtaining from Katmar. He - Katmar - is well known in web engineering circles as a top-flight process chemical engineer. He has developed various softwares (which I continue to recommend to all who are interested), one of which is for guess what? - packed columns. If Katmar told me to go to the bathroom for a solution to a packed column problem, I would do so - no questions asked.

I consider our members and our Forums lucky and fortunate to have sage advice from a veteren engineer such as Katmar.

I would also advise anyone reading this to go to his website and download his free Uconeer conversion software - the best conversion tool I have found all these years. And while you are there, look through all the software he offers.

Go to: http://www.katmarsof...rrer=Uconeer23H
to find out more about packed columns - and other subjects.

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