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Psa For Hydrogen Purification


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#1 chestudent2011

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Posted 21 February 2011 - 09:48 AM

I'm doing a plant design on hydrogen generation...

I have a problem in designing the equipment for pressure swing adsorption. Can anyone please guide me in the design of PSA?

#2 Art Montemayor

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Posted 21 February 2011 - 10:40 AM


Chestudent:

You state that you "have a problem in designing the equipment for pressure swing adsorption. That means you only have ONE problem.

What is that one problem? Be specific and define your problem in detail - which means basic data, background, sketches, calculations, and whatever else you have generated or accumulated regarding the problem.


#3 chestudent2011

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Posted 28 February 2011 - 09:18 AM

What I want is to calculate the dimensions of a four-bed PSA unit for hydrogen purification. Is there any way to find these dimensions without using simulation?



#4 Art Montemayor

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Posted 28 February 2011 - 10:59 AM


Chestudent:

Of course there is a way. That's the only way I have used to design, build, install, and operate adsorption units - the classical Unit Opeation way of calculating adsorption operations by using the textbooks and reference engineering databooks.

If you want to "design" an adsorption system, it is surely obvious that you must have the necessary key learnings acquired either through a university course or other means. And that being the case, then one applies those acquired learnings or teachings taught in the classroom or in literature.

That's the way I started and the way I still would do it - not by simulation, but using acquired experience and confidence.



#5 chestudent2011

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Posted 02 March 2011 - 06:13 AM

Sir Art,

Thank you for the reply...

In designing the PSA, I will be using a multibed system using activated carbon and ZMS 5A as adsorbents. The feed is composed of H2, CH4, CO2, N2, CO, and H20. How will I calculate for the bed dimensions given that this is now a multibed system? I already have the data for the breakthrough curves and the parameters such as density, particle diameter, etc for the adsorbents. I'm having a problem on how to proceed with the calculations.


Also, in one of the equations I got from a book, it says there to set the length of the bed. Is it safe to do that?

Thank you in advance.

#6 Art Montemayor

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Posted 06 March 2011 - 09:42 AM


Chestudent:

You ask the basic question once again: “How will I calculate for the bed dimensions ….”.

And I have already replied to this request: “……by using the textbooks and reference engineering databooks. If you want to "design" an adsorption system, it is surely obvious that you must have the necessary key learnings acquired either through a university course or other means. And that being the case, then one applies those acquired learnings or teachings taught in the classroom or in literature …”

I can recommend such textbooks like “Gas Purification” by Kohl & Riesenfeld, “Gas Conditioning and Processing” by John Campbell, “Engineering Databook” by GPSA, and your Unit Operations textbooks at university. We cannot teach Unit Operations on the Forum. We don’t have the resources or the mission to do that. We are here to help and advise you; we can even assist – but you must do the basic workload of learning and knowing what you are dealing with and what you have to know to solve the problem before you.

You cannot design for a specific "breakthrough" in an adsorption column. It just isn't practical because of the complex nature of the process. You cannot predict the breakthrough of a component with any accuracy or reliability. You have to design an adsorption column with the contingencies required due to a lack of certain specific and accurate information on adsorption. You can't just "throw" equations at an engineering problem and expect to resolve it that way. You have to use your logic, reasoning, and ingenuity. That is why using an equation you haven't even described or derived doesn't make sense. Logic tells you that you must calculate what is the recommended height (& diameter) of the required column - based on the knowledge and design techniques that you have been taught (or read and researched).




#7 ugEnergy

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Posted 08 March 2011 - 01:15 PM

doing same project, absolute best starting reference: Coulson and Richardsons, Chemical Engineering Design Vol. 6. there is a worked example to determine amount of 5A zeolite needed for adsorption of CH4 from H2 stream using 4 bed PSA plant, where required product recovery-90% and H2 purity-99.99%. subsequent explanation as to how to calculate vessel diameter and tangential length. Also information on costing and additional advice on pressure vessel design.

#8 chestudent2011

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Posted 10 March 2011 - 09:15 AM

I have a copy of Coulson and Richardson's Vol. 6 however I wasn't to locate the page where purification of hydrogen using 4-bed PSA unit is located.




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