17 replies to this topic

[AnbIran]

HI every one,

I'm sizing a tower for a project. Estimated diameter is very low (550 mm) and flow path length is low in result of it (lower than 16 in).

 

So now Should I increase diameter (to around 750 mm) or it is normal to have towers with such low diameter?

[Bobby Strain]

You should look at packing in lieu of trays.

 

Bobby

[AnbIran]

You should look at packing in lieu of trays.

 

Bobby

Yeah I thought about it but client wants tray tower

[Bobby Strain]

Clients don't always know what is best. What is the service? How many trays? You can't service such a small diameter vessel.

 

Bobby

[AnbIran]

Clients don't always know what is best. What is the service? How many trays? You can't service such a small diameter vessel.

 

Bobby

 It is a stabilizer in aromatic unit from pyrolysis gasoline hydrogenation, this column separates C5- from feed stream. 

[Pilesar]

There are specialist companies which supply column internals. Their engineers will give you definitive answers on what is possible and will recommend the feasible options. If you have a simulation, Koch-Glitsch or Sulzer or perhaps UOP should be able to give you a design. You will want expert advice to convince yourself and your client the best path forward.

[PingPong]

 

You should look at packing in lieu of trays.

 

Bobby

Yeah I thought about it but client wants tray tower

 

You could consider cartridge trays. The trays are connected to each other by tie rods and the whole section ("cartridge") is lowered into the small diameter column from above. To have enough trays multiple sections may be required and column will have to be multiple sections too with flanged connections.

 

https://www.google.c...iw=1112&bih=587

[breizh]

Hi,

Another great company to consult is Raschig.

Breizh.

Attached Files

•  separation tower design.pdf   1.41MB   46 downloads
•  Info RASCHIG Column Internals-1101.pdf   2.91MB   36 downloads

[shvet1]

Estimated diameter is very low (550 mm) 

 

Estimation is based on what? Where did you get a recommended velocity?

[AnbIran]

 

 

You should look at packing in lieu of trays.

 

Bobby

Yeah I thought about it but client wants tray tower

 

You could consider cartridge trays. The trays are connected to each other by tie rods and the whole section ("cartridge") is lowered into the small diameter column from above. To have enough trays multiple sections may be required and column will have to be multiple sections too with flanged connections.

 

https://www.google.c...iw=1112&bih=587

 

Thanks my friend, I hadn't heard about it. 

 

 

Hi,

Another great company to consult is Raschig.

Breizh.

Thanks bro for sharing documents.

 

 

 

Estimated diameter is very low (550 mm) 

 

Estimation is based on what? Where did you get a recommended velocity?

 

I estimated it by KG Tower and Hysys

[Bobby Strain]

What are you separating?

 

Bobby

[shvet1]

As far as I remember KG-tower and Hysys calculate trays components. Why do you asking? Why do you consider 16'' is low?

Why is 550 mm low? I have been working with ID 400 mm at a chemical facility and have seen many such cases.

 

Describe in details your logic and actions taken.

Edited by shvet1, 21 November 2023 - 07:53 AM.

[breizh]

Hi,

To get an approximation of the diameter of the column with trays, consider this equation (extract from my old notes (>40 years)).

 

D =[4 *Mv/ (pi*Kv* (Rov/(Rol-Rov)) ^0.5)] ^0.5 

 

D: diameter in meter

Mv: Mas flowrate vapor phase kg/h 

Rol: density liquid phase kg/m3

Rov: density gas phase kg/m3

Kv: coefficient function superficial tension and distance between plate, cf attachment 

 

distance between plates in centimeters

Superficial tension in dynes/cm

 

Hope this is helping you.

Breizh

Attached Files

•  approximation column diameter.pdf   196.53KB   31 downloads

[thaihy]

FRI has issued the guideline for minimum column ID which relates to the size of packing.

[latexman]

FRI has issued the guideline for minimum column ID which relates to the size of packing.

 

Can you attach the guideline, please?

[breizh]

Hi,

Attached another estimate for diameter sizing.

Breizh

Attached Files

•  column diameter estimation Towler Sinnot.pdf   302.47KB   16 downloads

[katmar]

My experience with cartridge trays has not been good.  It is difficult to get the tray sealed against the inside of the shell.  The most reliable method that I have found is to use sections with one or two trays per section plus a sandwich tray between the sections.  But all these flanges do add to the cost.

 

Speak to a specialist tray supplier to see what is the minimum diameter they can fabricate and then you can choose between the cost of making a column with a diameter larger than required versus the cost of a smaller column with many body flanges.

[AnbIran]

My experience with cartridge trays has not been good.  It is difficult to get the tray sealed against the inside of the shell.  The most reliable method that I have found is to use sections with one or two trays per section plus a sandwich tray between the sections.  But all these flanges do add to the cost.

 

Speak to a specialist tray supplier to see what is the minimum diameter they can fabricate and then you can choose between the cost of making a column with a diameter larger than required versus the cost of a smaller column with many body flanges.

 

Thank you for sharing your experience.

 

What are you separating?

 

Bobby

 

 

We are preparing suitable feed for reactors in an aromatics plant. actually, suitable feed starts from C6 naphthenic.