oxygen concentration brine versus fresh water

[caneng2002]

Are the O2 levels in brine lower then those in fresh water at a given temperature simply because the increased TDS of the brine prevents more oxygen from binding to other molecules?

Kevin

 

[gerhardl]

I am at all not knowledgeable in this field, but are you talking about a 'dynamic' or 'static situation', free mixed or bound after airation situation, free nature or 'stored' condinition, or theoretical possible absorbation values?

In a dynamic or 'real' situation I would imagine the real O2 content would depend more on the mixing dynamics than the actual binding possibillities.

Or am I completely wrong?

 

[zdas04]

The rate that a liquid can absorb a gas is described by Henry's Law. There are Henry's Law constants for pure water at atmospheric pressure and normal room temperature (actually a pretty chilly room, they use 60F). As you dig further into the physical phenomena you find that people have published factors and methodologies to adjust the constant for pressure (and all the sources I've found agree on the direction, but the magnitude varies from source to source). Some people have ventured to try to develop an algorithm for temperature, but not all sources agree even on the direction of the change and the magnitude varies widely.

Now to your original question, all the sources I've found agree that the "constant" changes with water chemistry, but I have been unable (with a lot of searching) to find anyone that would presume to quantify either the magnitude or the direction of the change. I've seen disolved O2 numbers for sea water and for distilled water over the years and they have never made sense--I'm thinking that the temperature effects are overwhelming the water chemistry effects, but the sample temperature is rarely captured with water samples so I've never been able to verify this. If anyone has a reliable algorithm for TDS vs. Henry's Law constant I'd love to see it.

David

 

[786392]

Dear kevin hello,
Somehow I am a seconder to David's concept;with specific typical reference to 'Sea Water'
Biggest Reservoire of Life contains Sufficient Oxygen absorbed/retained is in bulk nothing but mostly 'brine' of a kind.Accordingly I form the opinio that it is more the temperature (upto the liquid state of water) rather than other constituents wether dissolved,undissolved dispersed etc.


Best Regards
Qalander(Chem)

 

[caneng2002]

Gents, thank you for your comments.

gerhardl (Mechanical)
At this stage I was looking for some theoretical values.

zdas04 (Mechanical)
my brine source is from a solution mining stream for KCl and NaCl. I'm looking at de-oxyenating it using a vacuum deaerator driven by steam (rather then vacuum pumps).

Anyway the only O2 staturation data I could find for near staturated brine was a Dead Sea sample.

I'll keep looking.

 

[zdas04]

Was the Dead Sea sample quantative or qualitative? I'd love to see the data if it is quantative.

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

The main difference beteen humans and apes is that we have cooler tools

 

[unclesyd]

Here is an article concerning dissolved gases in seawater that somewhat echos the above posts. It too has the caveat about the uncertainty of the data.

http://www.seafriends.org.nz/oceano/seawater.htm#gases

 

[zdas04]

I love the disclaimer "Please note that these figures may be incorrect as too many different values have been published"

David

 

[caneng2002]

zdas

I have a pdf document by Nishri and Yaakov on Dead sea brine.

where do you want me to send it?

 

[zdas04]

I'd love to see it, but it might be better to upload it to engineering.com (hit the link below the new-message box) so anyone who wants to see it can get to it.

Thanks

David

 

[unclesyd]

You might be able to gleen a little data from these tables.
It

http://water.usgs.gov/software/DOTABLES/

I would also check and see if there is a DO probe that will take your concentration of chlorides.

 

[caneng2002]

Gents

I think I upload my brine doc correctly.

http://files.engineering.com/getfil...3df01e98b40&file=Sol_O2_in_Dead_Sea_Brine.pdf

 

[gunnarhole]

caneng2002

The presence of salt does reduce the solubility of O2 in water. Check the following article from Petroleum Technology Quarterly, Spring 1998. "Oxygen solubility in various alkanolamine/water mixtures" (see Figure 5).

http://www.gastreating.com/pdf/PTQ_Reprint.pdf

(you may have to register). Why this is I leave to others.

Regards,Gunnar

 

[dcasto]

we deareated both our brine and freshwater at our underground storage facilities. The systems wer both designed using the same air solubility rates.

We used a 20 foot packed column with vacuum pumps at 28 inches Hg to remove air.

 

[caneng2002]

dcasto

interesting. I decided to do the same thing with my performance spec, leave the O2 rates the same as water at the design temperature.

Who manufactured your system. I'm having problems finding bidders for this type of de-aerator. Most vendors want to use a thermal de-aerator which has an expensive operating cost.

Instead of vacuum pumps I want to feed the eductor with a local steam source to pull a vacuum in the tower.

Thanks

 

[dcasto]

Brown and root designed them in 1977. Zoom to this place on Google earth 28 59 00.87N 96 08 41.65. Its blurry, bu thats them on the north side of the smallest pond. Just say you heard about them.

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