Is industrial fluid/gas mixing principles able to be down scaled? 1

[priestyard]

Hi,

I'm trying to develop at compact in-line carbonation system, but need it for non-industrial use, so flow rate whould be many fold lower than what's in industiral use today.
At the moment, I'm not even sure this is possible, fluid dynamics wise.

I would prefer a static mixer unit for the purpose, but venturi mixing would be O.K.
I'm an electrical engineer, so my current knowlage is insufficient.

I have tried some different home made setups with kenix mixer inserts, but end result is far from acceptable.
Is anybody able to tell if this is at all theoretically possible, just by My description?

Specifications:
Liquid input:
Type: Water (H2O)
Flow rate: 0.24 m3/h
Temp: 8 C
Pressure: 3 kg/cm2G

Gas input:
Type: Carbon Dioxide (CO2)
Flow rate: 0.360 kg/h
Temperature 0 C
Pressure: 3 kg/cm2G

Mixed output:
Type: Carabonated Water
Flow rate: 0.24 m3/h
Temp: 5 C
Pressure: 1 kg/cm2G (atmospheric pressure)


I suspect that the low flow rate could be a challenge, but let me know your thoughts.
I know of several mixing systems allready in industrial use today, so on an industrial scale, this is absolutely possible.
But will it scale (down) ?

P.S. I tried to post some days ago, but I don't se my post anywhere. I also can't login with that old account, so I have made a new one. So, hopefully this is not at de facto double post.

Thanking in advance
priestyard

 

[Latexman]

The CO2 pressure is too low to get the usual concentration of CO2 in the water. 7-9 kg/cm2 is the usual pressure.

Good luck,
Latexman

 

[priestyard]

Thanks for the heads up on the pressure, Latexman.

I think I need to clarify my current test setup. It's kind of crude, cause I just use a T connector to join the two streams, and letting it throught the mixer stage. I'm using 10x Ø20mm kenix inserts with total of 50 mixing elements. I have tried to crank up the co2 pressure to the point where both co2 gas and (not so) carbonated water is coming out the tube, but still far from acceptable saturation is obtained (you can hardly feel/taste the co2).

I have ordered some Ø10 and Ø8mm kenix mixer elements to try with smaler pipe diameter, on the layman assumption that higher mixing velocity would help improve mixing effeciency.
I have also tried the venturi approach, and got better saturation that my current static mixing setup, but stil not enough. It's difficult to make your own venturi mixer. It seems as some kind of voodoo, to make that work out.

But, would it be safe to expect the down scaling to be possibe?

Thanking in advance
priestyard

 

[Compositepro]

To dissolve CO2 rapidly into water you need high interfacial contact area between the two phases and high pressure. You will need to over carbonate because some will be lost when you reduce pressure down to atmospheric.

Static mixers are not great for making small bubbles/droplets, which requires high shear.

I suggest that you that you pump water through an atomizing nozzle into a high pressure chamber filled with CO2. Draw-off carbonated water from the bottom of the chamber (pipe). Level control the water in the chamber so all bubbles can separate from the water before it is reduced in pressure. Expanding bubbles neucleate more bubbles and release the CO2. Reducing the water pressure through a long capillary tube rather than though a high turbulence needle vlave will also help.

An alternative to spray would a packed column approach to contacting the water and CO2. You need to be over 100 psi as Latexman said.

 

[priestyard]

Thank you for the suggestions, Compositepro.
Your suggested method with a pressurized vessel is the defacto standard for current fountain systems. And thats exactly what I'm trying to avoid.
A pressure vessel with water will have to be cleaned and serviced regulary. Would requre a pressure pump. Extra safety prequations. Is relatively bulky. And also requires more measurements and logics.
I appreciate your help, and apologize that I didn't mention that I want to avoid the traditional approach, and saving you the trouble.

Maybe higher shear by injecting the co2 into the water stream through a atomizing nozzle would do the trick.
100psi should only be neccessary with traditional pressurerized vessel design. But more that the the current 40-50 psi might be needed for static mixing or venturi, though.

If current industrial systems gives a satisfying result, I can't see how, in theory, that couldn't be scaled down.

Take a look at following documents with patents and atual products:

http://www.haffmans.nl/import/assetmanager/2/13192/CCR E 05-10 LR.pdf

http://www.steinfurth.com/files/ICS610_english.pdf

http://www.freepatentsonline.com/3761066.pdf

http://www.freepatentsonline.com/7374156.pdf

http://www.freepatentsonline.com/4123800.pdf

http://www.freepatentsonline.com/5842600.pdf

I know that a granted patent dosen't guarantee a working device.

Thanking in advance
priestyard