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Pressure In And Around Distillation Column

distillation column pressure calculation feed bottom product dew point design

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#1 C.Eng.Student

C.Eng.Student

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Posted 23 February 2017 - 04:54 AM

Hello,

 

I am trying to design a multi component distillation column for the separation of the following components:

 

FEED: 

  • Ethylene Oxide
  • Water
  • Carbon Dioxide
  • Acetaldehyde
  • Formaldehyde
  • Ethylene
  • Oxygen
  • Methane

DISTILLATE:

  • Methane
  • Ethylene
  • Oxygen
  • Formaldehyde
  • Acetaldehyde
  • Carbon Dioxide
  • Ethylene Oxide

BOTTOM:

  • Ethylene Oxide
  • Water
  • Formaldehyde
  • Acetaldehyde 

The feed temperature is 40 C (I haven't made any calculations for this, I have a heat exchanger before the feed enters the column which will heat up/cool down the stream) and the cooling water I am going to use is 35 C.

 

I understand the pressure at the top will be lower than that at the bottom but I am struggling to calculate the exact pressure at the feed, top and bottom.

 

Question:

  1. What information do I need to calculate the pressure in all three cases 
  2. How would I calculate the pressure
  3. Is the temperature I've got reasonable?

 

Thanks for all the answers in advance!



#2 Art Montemayor

Art Montemayor

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Posted 23 February 2017 - 05:36 PM

C.Eng.Student;

 

As a typical, naive student you are posting a very vague and unspecific problem.
Is this an assignment from an instructor?  If so, it would be much simpler and more descriptive if you stated so or quoted the exact wording you were given.

 

For example, you can’t have a “distillation” problem with dissolved gases involved.  You have a stripping operation required first before you can actually “distill” a liquid mixture of liquid components.  If you have an aqueous solution, then you probably have nothing more than a stripping operation since you don’t show any water in the overheads.  Am I correct?  Please state the condition of the feed stream: liquid? Composition of the mixture? Pressure of the mixture?  Composition is of interest since you show hydrocarbons and oxygen in the mixture.

 

Composition of the overheads?  Composition of the bottoms product?  It is not enough to simply state the identities of the components.  State the compositions.



#3 C.Eng.Student

C.Eng.Student

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Posted 06 March 2017 - 10:25 AM

C.Eng.Student;

 

As a typical, naive student you are posting a very vague and unspecific problem.
Is this an assignment from an instructor?  If so, it would be much simpler and more descriptive if you stated so or quoted the exact wording you were given.

 

For example, you can’t have a “distillation” problem with dissolved gases involved.  You have a stripping operation required first before you can actually “distill” a liquid mixture of liquid components.  If you have an aqueous solution, then you probably have nothing more than a stripping operation since you don’t show any water in the overheads.  Am I correct?  Please state the condition of the feed stream: liquid? Composition of the mixture? Pressure of the mixture?  Composition is of interest since you show hydrocarbons and oxygen in the mixture.

 

Composition of the overheads?  Composition of the bottoms product?  It is not enough to simply state the identities of the components.  State the compositions.

 

Apologies sir, please find the attached excel sheet with all the information.

 

I am not 100% on what sort of operation I should be doing here, the feed is liquid however I think some gases may be dissolved in the solution.

 

Please could you advise on what sort of operation to do and any comments on the temperatures/pressures you see on the sheet.

 

Thanks

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