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[Cariemb0]

Hey there! I'm currently busy doing a project involving separation of Air. I've done it using Cryogenic distillation. However, I have been unable to find out what fluid is used in the condenser or reboiler (as well as the Thermodynamic Properties.) I'm currently using Argon as the coolant in the condenser but I can't seem to find a suitable agent for use in the reboiler.

Also, the oxygen exiting the reboiler is @ -165oC and needs to be heated to 250oC. I think it should be done in 2 steps, step 1 to get it over 0oC and then use high P steam to get it to 250oC. Is this do-able? And what could I possibly use in the first step?

[Art Montemayor]

Cariembo:

If you use the "SEARCH" feature in our Forums, using the key word "Linde", you will find a large variety of threads based on this subject – such as:

http://www.cheresources.com/invision/index.php?showtopic=5113&pid=16283&st=0&#entry16283

http://www.cheresources.com/invision/index.php?showtopic=3528&hl=Linde

Air separation is very do-able. I spent the first years of my engineering career doing just that – every day, 350 days a year, non-stop. One of my posts states the following:

"Carl von Linde invented a method to produce essentially pure Oxygen and Nitrogen by liquefying air and subsequently distilling it. He did this in 1895 - well over a hundred years ago! By 1906 he had refined his invention to the point where he employed a "double column" - a unique, and "intensified" distillation operation where a low-pressure(LP) distillation column (@ 5 psig) was physically mounted and soldered on top of a high-pressure (HP) distillation column (@ 75 psig) and a Nitrogen condenser was mounted in-between both columns. This N2 condenser served as the total condenser for the HP column and furnished it reflux - by gravity. It also functioned as the reboiler for the LP column! Now, that's ingenuity and total INTENSIFICATION! But wait, the intensification didn't stop there. All heat exchangers, valves, and interconnected piping were put intimately together within one, hermetic shell (called the "Cold Box") and were all insulated with poured "rock wool". This Cold Box received compressed air as input and produced pure Oxygen and pure Nitrogen. To this date, every so-called "intensified process I've seen or read about is nothing compared to Linde's achievement. To this day the same, basic design as put together by Linde over 100 years ago is the principal component for the production of Oxygen, Nitrogen, and Argon in both the gaseous and liquefied states. None of the principal features of the design have changed."

There has been over 100 years of accumulated know-how in the process and all of it has been written or talked about. If you don't have detailed information on all the air separation processes it must be because you either haven't spent enough time looking or you are not looking in the right places. The information is there – in text books, manuals, courses, lectures, papers, articles, journals, etc.

I urge you to increase your efforts in doing research and looking into the air separation process as developed by Linde. You will never regret the time spent in learning about real engineering. All the information is there. I know it, because I still have the hand calculations I did (including the McCabe-Thiele Diagram) in designing a typical air separation column for producing liquid Oxygen, liquid Nitrogen, and liquid Argon. Now, 45 years later you are telling us you can't find information to do the same thing. I don't believe you because I've been there and done it.