vacuum seawater deaeration pumps -seawater gas concs.

[frogcurry]

Hi,

I'm attempting to assess (at a preliminary stage) whether a vacuum pump system (liquid ring pump and ejector operating in two stages) is adequate for an increase in duty in the seawater flow. I have a pump curve for the liquid ring pump but no other information. It gives a curve of torr against a flowrate (air at 20C).

My assumption is that I need to know the amount of dissolved oxygen and other gases in the seawater against pressure, get a flowrate of gases and vacuum required - then compare against the pump curve.

However, I can't find a good source of info. on the amount of gases that are in seawater (North Sea spec.). This seems to be crucial - does anyone have a reference? (Since the vacuum pump will pull all sorts of gases the oxygen alone won't be sufficient so I don't think I can just estimate.)

Also I would appreciate any suggestions on how to assess the ejector capacity - I have no experience of working with these items.

Thanks.

 

[rmw]

This paper has a graph of the soluability of oxygen in water vs temperature.

I don't think that it matters whether the water is fresh water or sea water, or that is to say I don't think the difference is measurable.

rmw

http://asme.pinetec.com/ijpgc2000/data/pdfs/15033.pdf

 

[25362]

Salinity affects somewhat the solubilities of gases. Thus sea water dissolves about 80% of the amount ~zero-salt water would.
Temperatures, depth, etc., are all factors that affect solubilities.

Typical solubilities at 25^oC, in mg/kg would be:
nitrogen, 11; oxygen, 7; argon 0.4.
At 15^oC, an increase of 20% is considered reasonable.