Efficiency of air sparger to remove CO2 from brine

[c2sco]

Can anyone offer any practical experience or test data on the likely performance I'll get if I sparge air into a tank containing brine that has dissolved CO2 in it?
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[m777182]

On a lab scale we adjust the pH and apply ultrasonic waves. Heating or lowering pressure removes CO2 much more slowly.
m777182

 

[c2sco]

Thanks for that. We do reduce the pH to about 3 to 4, but ultrasonics isn't very practical in a 40 m3 tank! The flow's too large to economically heat it either. Calculations show that air sparging will do the amount of removal that we need to do, the theoretical amount in our case being about 0.5m3 air per m3 brine, but I don't know how efficient it will be, ie the actual air usage.
Regards,
Stuart

 

[m777182]

The efficiency of the air consumption depends on your sparging system.There are some papers about specific energy consumption per sq m of bubbles area for a different equipment if you are designing new one but as I understand you already have it. Years ago I had a book -Danckwerts P.V., Gas-Liquid Reactions where there was a lot about absorpion and desorpion of CO2.
m777182

 

[c2sco]

Thanks again.

We already have the tanks, acting as head tanks in the brine distribution system and they're just empty, unheated atmospheric tanks. The brine spec is changing in the future which will mean it will have more dissolved CO2 in it. The hope is that by sparging air in we can remove this extra CO2 which would have a negative effect on some parts of the subsequent processes. So the tanks exist, but any spargers would be new. Brine scales equipment so we hope to make the holes as big as possible but as you say hole size and efficiency will act against each other - the question is, how much!

I've found reference to the book - it was published in 1970 but seems to be no longer in print unless someone other then McGraw-Hill now print it. Maybe I'll find a secondhand copy.