2 replies to this topic

[Leonard W]

In terms of gas dryness at the output of a conventional separator. I have seen specifications such as 0.1USG/MMSCFD and 99.9% droplets > 10micron. Since I want to make comparison between these separators, I would like to know if there is a way for me to convert either of each spec to the other? Are the 2 measurements related in anyway?

[Art Montemayor]

Leonard:

 

Firstly, I think you are writing about a typical gas-liquid separator.  If not, please state so.  On a practical basis, it is not possible for such a separator to separate out all the liquid contained in a gas stream.  And even if it could, the gaseous product would be a gas 100% saturated with the related liquid.  Therefore, the gas product can never be defined as "DRY".  If you have taken Physical Chemistry successfully, then you can understand this simple phase equilibria.  If not, we can't continue to explain.

 

Drs. W.D. Monnery and W.Y. Svrcek published an article, "Analytical Study of Liquid/Vapour Separation Efficiency", in Sep 2000 in which they discuss the efficiency of separating certain liquid droplet sizes and quantities in different types of separators.  I have what I would call a corrupted copy of that paper that has the droplet size and quantities calculations missing as well as some of the photos/diagrams of the separators used.  This, I have been told is the "latest and greatest" attempt to quantify the degree and efficiency of liquid separation from gas streams by using industrial type separators.  You can find copies of this paper on the internet and can download a copy - but it will probably be in the same state as mine.

 

I have never heard of or read about a liquid droplet counter or size measurement device.  In my opinion, the best you can do is estimate the quantity and size of water droplets contained in a flowing gas stream.  And that estimate is always open to proof or critique.  But I hope and pray someone will come up with a practical and credible solution.

 

Perhaps some of our very knowledgeable and expert members - like Bobby Strain can help shed some light on the topic.

 

Let's hope he reads this thread and responds with some of his experience.

[Bobby Strain]

Well, I have the article Art mentions. But it was apparently published without the appendices. But the test equipment is described as a 10-inch diameter vessel. I wouldn't expect to get meaningful information from a separator of this diameter. And, since we accept that the normal demisting devices don't remove 100% of the entrained liquid, where complete removal is required we employ a filter-separator to remove the last traces. You will find this most frequently employed upstream of a mol sieve dehydrator. Lurking somewhere on the web is a master's thesis that presumes to address the query. Maybe a Google search will find it. I believe it was one of the institutions in Norway. Good luck.

 

Bobby