4 replies to this topic

[Sze Jin]

Hello all and good day!

 

I am currently pursuing my Chemical Engineering Degree and have come across a design problem that I could not solve. 

 

I have attached the PFD of the given question:

 

Solvent is DEA (Diethanolamine)

LINK: http://i.imgur.com/7ULuJwY.jpg

 

The item that I am tasked to design is T-402 (Solvent Regeneration Tower), and the information that I am given are as follows:

 

Temperature, pressure, vapor fraction, composition and flowrate of stream 21, 26, 29 (related to T-402)

 

I tried designing with Aspen HYSYS distillation component, but I could not come to a satisfactory conclusion where I can justify my selections. I could set my parameters as I like (reflux, pressure of condenser and reboiler, etc) and still be able to solve using HYSYS. The HYSYS file is attached below as .zip

 

My question for the HYSYS simulation is, are there any ways to justify my selection of parameters? I feel like I am missing a very important thing, but I'm not too sure what.

 

------------

 

As far as hand calculations go, I have made an excel sheet to calculate mol fraction, vapor pressure from perry's handbook, then I'm not too sure if I'm doing the right thing. The sheet is attached below.

 

I am referring to a book "Chemical Engineering Design" by Ray Sinnott, and from the methods stated for design in chapter 11, I need the relative volatility.

 

I could not get those parameters based on the information given.

 

Thank you for taking the time to read. 

Sze Jin

Attached Files

•  Vapor Pressure Calc.xlsx   48.76KB   34 downloads
•  T402.zip   118.47KB   19 downloads

Edited by Sze Jin, 04 October 2014 - 02:14 AM.

[Art Montemayor]

Sze Jin:

 

We can’t see what you have uploaded as your PFD.  The drawing is the size of a postage stamp.  Why don’t you simply generate your own PFD instead of relying on someone else?

 

I think you are dealing with an acid gas removal process – since you mention Diethanolamine.  Are you simply removing CO₂ from a feed gas?  What is the feed gas and its composition?

 

If you are dealing with an amine process to remove CO₂, then you should be studying such texts or documents as:

• Kohl and Nielsen, “Gas Purification”
• The GPSA Engineering Databook
• John Campbell’s Gas Conditioning and Processing

I don’t think Sinott’s expertise in amine systems can compare with the above.

 

If you are trying to design a DEA stripper, then you have to realize that amine strippers – just like amine absorbers – are not calculated.  They are empirically sized.  You can run all the simulation programs you want to run, but in the end, the result will be based on experience and existing empirical methods.  Read the above literature and you will find that conclusion.

 

DEA is NOT a solvent.  As used, it is an aqueous absorbing solution. 

[Sze Jin]

Art Montemayor, thank you for your informative response! I have little to none in terms of knowledge in amine system related design and I'm still trying to learn now

 

With regards to the PFD, I have updated the photo, and added the link below the picture. Apologies as I did not realize the picture was too small.

 

From what I have been provided, the objective is to remove CO₂ from the liquid feed (stream 21). Compositions are in the table below the drawings.

 

Thank you for the information, I will try looking up those textbooks and see what I can come up with for my design.

 

Have a great day! 

Sze Jin

[breizh]

Sze Jin,

I found this book interesting , to add to the list provided by Art :
Gas treating -Absorption theory and practice by DAG.A.EIMER .



Breizh

[Padmakar Katre]

Hi,

 

Read Gas Purification Handbook by Kohl, it's indeed a great source for gas treating methodologies with plenty of data & experience based guidelines.