Nitrogen for Removal of Oxygen from Water
Nitrogen for Removal of Oxygen from Water
(OP)
Does anyone know of a standard for how much nitrogen is required to bubble through a unit of water in order to effectively remove oxygen from the water? Trying to decide on an appropriate flow rate of nitrogen through a bulk water tank in order to reduce oxygen pitting in components downstream of the tank. Any help would be appreciated. Thanks!





RE: Nitrogen for Removal of Oxygen from Water
best wishes,
sshep
RE: Nitrogen for Removal of Oxygen from Water
As said by sshep, steam is a better choice. Yet just sparging N2 is technically feasible.
As a ball park figure use us (gas slip velocity of 1 cm/s)
us=volumetric rate / cross section
RE: Nitrogen for Removal of Oxygen from Water
Bringing water to a boil to deoxygenate it makes sense IF it's boiler feed water, but not a whole lot of sense for other water use purposes- unless LP steam in your plant is both clean and "free". Don't count on the latter, because the boiler feed water to make that steam isn't free, even if the energy is essentially free.
Yes the kLa will be bad with a single sparger in a big tank. Yes you will "waste nitrogen" relative to what you could achieve in a properly designed continuous contactor. But you don't need to go down to 9 ppb oxygen for the OP's purposes.
How much nitrogen depends on lots of stuff: your target DO level, the purity of the N2, geometry of the tank and sparger, size of bubbles etc. etc. Not a question we're going to be able to answer for you for free with any accuracy on a public forum I'm afraid.
RE: Nitrogen for Removal of Oxygen from Water
Have you contemplated the use of vacuum ?
Can you describe the water volumes involved and the purpose of the desorption ? Are scavenging chemicals allowed ?
RE: Nitrogen for Removal of Oxygen from Water
Unlike nitrogen sparging it may not be possible to do this in your tank unless your tank is really a vessel. But if you can de-aerate the water under vacuum and then simply inert the tank headspace with nitrogen, you may be able to get away with this approach.
RE: Nitrogen for Removal of Oxygen from Water
HTH
RE: Nitrogen for Removal of Oxygen from Water
The method used in the power industry is vacuum degasification and nitrogen inerting of the tank.
The degasification unit does not have to be large as a sidestream arrangement can be used on the tank.
RE: Nitrogen for Removal of Oxygen from Water
RE: Nitrogen for Removal of Oxygen from Water
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Speaking with a rep from Grenland, I was told that 1:1 volume ration of N2 to Water will strip O2 down to 20 ppb or less. Not sure if it was a 1:1 volume ratio at operating conditions of ~3 - 5 barg, or normal meteres cube per hour of N2.
RE: Nitrogen for Removal of Oxygen from Water
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RE: Nitrogen for Removal of Oxygen from Water