SLOPS OIL / WATER GRAVITY SEPARATION

[roker]

Hello,

Is it a correct assumption that the maximum phase separation that can be achieved is the solubility of water in oil and oil in water ?

Does centrifuge phase separation achieve separation levels higher than gravity separation?

regards,
roker

 

[bimr]

The term for this is free oil. If you want to remove the dissolved or emulsified oil, then you would need some type of chemical treatment to break the oil our of solution.

 

[gr2vessels]

Suspended oil can be separated down to less than 0.5 ppm with industrial centrifugal separators (hydrocyclone).

 

[MortenA]

@gr2vessel:

Could you point me to a vendor that will promise that performance? We struggle to get below 30 ppm.

 

[crshears]

I stumbled upon some information about a device called the Anvar / ELF Coalescer. It took some searching, but I eventually found the following links:

http://infohouse.p2ric.org/ref/31/30416.pdf

and

http://infohouse.p2ric.org/ref/31/30417.pdf

There is also the single page at

http://www.larive-environnement.fr/Site Larive anglais/coalesceur.htm

A company named Graver Water Systems [

http://graver.com/

] purports to supply these coalescers, which are capable of removing oil from condensate down to a purity of 1 part per million - - but they've never responded to my e-mails; maybe you'll have better luck...if you do, let us all know!

 

[gr2vessels]

One quick example of large flow industrial hydrocyclone, under 5 ppm.

http://spel.com.au/products/puraceptor/?gclid=CPWZx5L3krkCFYJU4god8R4AiA

There are other specialised separators, I remember a brand Vortoil ( I have designed for them some 15 years ago in Australia a 'high tech' oily water separator in two stages down to 1 ppm). The process designer is still alive, but retired long ago.
Need a bit of work on the internet and also with some reputed fabricators.
Cheers,
gr2vessels

 

[KernOily]

Roker - No. The maximum (economic) separation that can be achieved is a function of the oil droplet size. This is assuming the oil and water exist as distinct phases and not as an emulsion. A stable emulsion will not separate, at least in economic plant operation time, without addition of heat, chemical, and/or residence time.

The separation of the distinct oil-water phases by gravity can be predicted using a Stokes law analysis. (See Perry's). To do that you need some idea of the oil droplet size. You can speed up the separation by, again, time love and tenderness (ha - time, heat, and chemical) or by increasing the gravity, which is what the hydrocyclone does. Or by introducing tiny gas bubbles to agglomerate the oil particles together so the Stokes law forces work faster (see: WEMCO depurator, or induced/dissolved gas flotation cell).

Yes - Centrifugal separation will achieve better separation than (unassisted) gravity alone.