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Diaphragm Hydrogen Compressor Suction Filter


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#1 FrankSeipel

FrankSeipel

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Posted 08 March 2014 - 09:03 AM

We operate a process wherein Hydrogen is recycled to a hydrotreater via a diaphragm gas compressor.  We run at 1100-1300 psi discharge.  After changing hydrotreater catalyst, we're going through a lot of diaphragms, the likely cause seems to be attrition/fines from catalyst.  We are already using a fine metal mesh witches hat conical filter.  There is also a separator in the suction line to compressor.  The equipment designer says there isn't really anything else that can be done to save multiple diaphragm failures/changeouts after reloading catalyst.  I was wondering if anyone has come up with anything for this problem.  This is a small hydrotreater, ~25 GPM feed rate on liquid side, I can provide gas flow rates but don't have any information on the fines particle size distribution.  If anyone can point me towards design guidelines for what mesh size ought to be equipped for such an application that may be helpful also.  I wasn't sure if sintered metal might work here but I'd need some guidance.  Seems to me it would be acceptable to suffer a higher pressure drop the first week of operation if that didn't mean going through diaphragms.

 



#2 Art Montemayor

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Posted 08 March 2014 - 11:47 AM

Frank:

 

What I have done in the past in this type of compressor protection application is that I call a previously selected filter fabricator and ask for their advice on what fine filtering device they can furnish for the application.  I would already know the required design gas flow rate for the compressor and the filter fabricator can generate the corresponding pressure drops for the filters that can be supplied.

 

I would select the finest (smallest particle size filter) that can furnish the highest allowable pressure drop.  In other words, I can only filter out the smallest particles that can be designed for.  Also, I have to stay within the positive suction pressure limits the compressor is designed for.  Therefore, I compromise between both requirements - and that is as far as I can go practically.   The ideal situation is one where you select a filter that will capture the smallest particle you can imagine and still give you an acceptable pressure drop.  But that is subject to the reality of what is available or can be manufactured.

 

A mechanical separator is of little or no use if you are indeed suffering from attrition catalyst fines damaging your diaphragms.  A very fine filter is the only device that can practically capture the contaminants - but at the price of suffering the related pressure drop.  The finer the captured particles are, the greater will be the resultant pressure drop across the filter - and the lower will be the suction pressure into the compressor.






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