4 replies to this topic

[rgrasmeder]

We currently purchase high purity ethylene (99.9995% pure or better) from a vendor but we need to reduce the moisture content even more.  The product contains less than 1ppm moisture now, but ideally we'd like that to be reduced even below 0.1ppm if that is possible.  Does anyone know of anything that is commercially available that we could pass the ethylene through?  If not, we are a gas company (Air Liquide) so we do have access to other equipment.  A molecular sieve trap comes immediately to mind, but not sure if that would work or not.  Any information would be greatly appreciated.

[Bobby Strain]

Have you talked with the purchaser of the ethylene? Most polymer processes have a guard bed on the ethylene supply. My recollection is that molecular sieves are used for this function. If your customer doesn't have any recommendations, they might refer you to whomever licenses the technology to them. Let us know what you find.

 

Bobby

[Art Montemayor]

 

How do you accurately test for an ethylene purity in excess of 5 nines (99.999% - by volume, I assume)?

 

Also, how do you test for a water dewpoint of 0.1 ppm (also by volume, I assume)?

 

I am very interested in finding out the analytical method and/or procedure.

[rgrasmeder]

Thank you for your replies Bobby and Art.  Bobby, I asked my manager to ask the vendor if it would be possible to get specially prepared ethylene with the lowest moisture content they can do.  He is also going to ask them what process they use to remove the moisture, but we doubt they will divulge that.  Art - we go by the manufacturer's certificaiton, however we have the capacity to analyze ethylene here using gas chromatography.  We can analyze well up to C4.  We analyze the O2 using a Delta F oxygen analyzer.  The one thing we can't do well is moisture (figures).  We use a Panametrics analyzer but our lab guys tell me that is only good to around 1ppm..maybe.  So again, we are relying on the manufacturer's analysis for the certified contaminants.  And BTW, our analysis of the ethylene matches what we are getting from the vendor pretty well.  If I find out anything else, I will let you know.  Again, thank you for your replies.

[Dazzler]

UOP is one well known supplier of "mol siv" adsorbents.  You may wish to talk with such gas treatment vendors.