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Air Separation


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#1 Liker010

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Posted 27 February 2015 - 10:02 AM

Im working now in air separation plant, can any one here explain more what gas lift is?

And what is the importance of reflux?

#2 Art Montemayor

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Posted 27 February 2015 - 12:31 PM

Are you a Co-Op student, working and studying?

 

The only place I’ve worked on Gas Lift related projects is in Gas and Oil Upstream projects.  I’ve never heard of the term gas lift in an Air Separation Unit.

 

Reflux is a very important topic related to distillation Unit Operations and is something you should have had drilled into you in your Chemical Engineering Unit Operations courses.  Are you familiar with the McCabe-Thiele method of calculating a distillation operation?  It is considered to be the simplest and perhaps most instructive method for the analysis of binary distillation and you should be thoroughly versed in it.  You should have done various distillation problems using the method.  The theory of distillation is mainly based on producing a specific overhead vapor that is in equilibrium with the saturated liquid on the top-most tray.   This is related to the "equal molal" overflow principle, L/V.   The purity of this liquid depends in large part to the composition of the reflux liquid that is recycled from the overheads condenser back to the top trays in order to form that equilibrium.  This is graphically depicted in the McCabe-Thiele form and method, step-by-step.  It is very important that you immerse yourself in dominating the method if you are to understand what is going on in a standard Linde air separation double column.  There is abundant material to study in the internet on the McCabe-Thiele method.



#3 Liker010

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Posted 27 February 2015 - 08:23 PM

Ok, thanks for the reply, im working in air separation plant and i just cant picture out whats going on in high pressure column,

I know that LIQUID AIR from main heat exchanger , liquide turbine and expander turbine with -160 deg c will feed the lower column.

This is my analysis,

The pressure of our high pressure column is @ 4.17 bar, and because of that pressure, the RICH LIQUIDE @ lower part of high pressure column will produce, the LEAN LIQUIDE and LIQUIDE NITOGEN @ top part will produce. Even the PRODUCT LIQUIDE OXYGEN will produce. My question is, is there a equipment inside the high pressure column like reboiler or something that makes this separation happen? Or the pressure itself ( 4.17 bar) of the HPC makes the separation happen.?( pls answer this question)

Another thing is about low pressure column, here is my understanding, I hope you will high light and correct me if there is somthing wrong on my analysis.

Our low pressure column works on 340mBAR,
The RICH LIQUIDE will go to subcooler then feed to LOW PRESSURE COLUMN as well as the LEAN LIQUIDE. It will go to SUB COOLER then feed to LPC. Then, what will happen, ? Is this two liquide will fall to main vaporizer??then waste nitrogen will be formed?

Also, why another LIQUIDE AIR from high pressure will feed on LPC? Is this 3 ( liquide air, rich oxygen, and lean liquide) will reacts to each other? Is it with connection to the pressure on the low pressure column?

Hope you understand my questions,

Tn alot.

After understanding this.

I will ask about argon production..

Tnx!!

#4 Art Montemayor

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Posted 27 February 2015 - 10:17 PM

Please answer the question I asked you in my first post.

 

I have written many, many detailed descriptions and detailed drawings of Air Separation columns and how they are operated.  Please use our SEARCH engine to find all these threads and read them.  You will find all your information in these threads.  I should not have to keep repeating the same information for over 15 years.



#5 Liker010

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Posted 27 February 2015 - 11:41 PM

Ok tnx..

Now im working in air separation plant, it my first week in air separation plant and they want me discuss the process on monday...

Any ways..
Thanks for the help..
God bless...

#6 Bodhisatya

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Posted 28 February 2015 - 12:18 PM

http://www.cheresour...-double-column/

 

Dear 

 

As I understand you need to get your basics cleared before going into the details of Air Lift and other factors.Air Lift is used in ASUs,and will try to provide u some insights once ur basic is cleared. 

 

Please follow my above link ,also ART sir's numerous post on the said subject.

 

From your post I fathom u are using Claude cycle i.e Turbine outlet air is being fed to HPC. But I am not getting your point on Liquid Air from HPC to LPC. Can you please upload a sketch of the chosen cycle.Please be clear there is no reaction happening between Liquid feeds to LPC.

 

The Basic is to understand why HPC and LPC operates at two different pressure

 

Regards

Bodhisatya



#7 Bodhisatya

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Posted 28 February 2015 - 12:26 PM

The pressure of our high pressure column is @ 4.17 bar, and because of that pressure, the RICH LIQUIDE @ lower part of high pressure column will produce, the LEAN LIQUIDE and LIQUIDE NITOGEN @ top part will produce. Even the PRODUCT LIQUIDE OXYGEN will produce. My question is, is there a equipment inside the high pressure column like reboiler or something that makes this separation happen? Or the pressure itself ( 4.17 bar) of the HPC makes the separation happen.?( pls answer this question)

 

The max Conc of Oxygen in Rich Liquid at the bottom sump of HPC is 35 -40 % (depending upon the no of trays used),so how do u say that Product Liq Oxygen is produced (whose general purity is above 90 %).

 

The Intregrated Reboiler Condenser ,(Condenser for HPC and Rebolier for LPC) produce PL (Poor Liquid,Poor in Oxygen i.e Pure Liquid Nitrogen) which serves as a reflux for the up coming vapor.It strips away the oxygen in the vapor and get collected at the bottom as RL,where as the upward vapor gets enriched in Nitrogen (This is basic Distillation Principle).

 

Pressure alone can never a role in Seperation,it facilities the ease or difficult of separation as relative Volatility is a function of pressure ,but for any distillation to happen ,mass transfer is must ,which happens by supply of reflux.

 

Bodhisatya 


Edited by Bodhisatya, 28 February 2015 - 12:27 PM.


#8 Liker010

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Posted 02 March 2015 - 07:40 AM

Mmmm.. Ok..

Another question is about the bubbles..

What are the factors that affect to bubbles content.

How to maintain it?

Or, do you have video on youtube discussing the ditillation process of air separation?
I hope tou have..

I aslo wish that you will epalin here why there is high pressure and lo pressure column.

Thank you very much.

#9 Bodhisatya

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Posted 02 March 2015 - 09:58 AM

Please refer to the link provided in my previous post,it explains the requirement of High Pressure and Low Pressure column.

 

No I don't have that video,so I can't get your question on bubbles.

 

Also as requested please upload a sketch of the Cycle selected by you.

 

Bodhisatya



#10 daytauler

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Posted 03 March 2015 - 05:06 AM

Hi,

 

I am presently troubleshooting an ASU unit which is not making liquid in the HP column following a complete defrost. what handles can I use to resolve the issue.

 

thanks

 

Daytauler



#11 Art Montemayor

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Posted 03 March 2015 - 09:37 AM

Daytauler:

 

This is the STUDENT Forum.  If you have an operational industrial process problem, please use the Industrial Professional Forum to post your query.  I will delete your post here after a couple of days.  Let's keep some intelligent order and logic in our Forums, please.

 

Unfortunately the OP (original poster) in this thread has not responded to my initial question.  This reveals a characteristic of immaturity, so I'm assuming he/she is a student who has yet to grow up.  Our Forum documentation needs organization and scrutiny in order to have useful and organized archives - especially for our SEARCH engine to work effectively.  That is why we have separate Student and Professional Forums.  Your query can be addressed and answered in the Professional Forum by professionals.



#12 Bodhisatya

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Posted 03 March 2015 - 11:07 AM

Hi,

 

I am presently troubleshooting an ASU unit which is not making liquid in the HP column following a complete defrost. what handles can I use to resolve the issue.

 

thanks

 

Daytauler

As instructed by ART Sir ,please post your question in the Concerned section and we will try to provide a solution.Also it's not wise to hijack someone's thread.Please start a new thread

 

Bodhisatya 



#13 Liker010

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Posted 07 March 2015 - 05:52 AM

Sorry for the late update..

Im working as trainee in air separation plant.

Now i can picture out whats going on inside the cold box..

My problem now is about the bubbles or %02

Can any one here explain more about bubble?
I mean, what is bubble?

What are the factors that makes bubble go high or go low..

Thank you.

Fyi. I dont know how to upload any file here in the forum..

I hope you profesionals Makes a video showing how air separation goes on..

Thanks again!!




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