Gas dissolution rate in water
Gas dissolution rate in water
(OP)
Hello,
I am trying to calculate the gas loss rate in a pressure vessel, which is connected to a pipeline. The upper part of this cylindrical tank will be filled with air under pressure, and the lower part will be filled with the fluid pumped, which is normally water. The air will be compressed when the pressure in the fluid goes up and viceversa, preventing the pressure in the pipeline to rise or dip too much). In other words, the air acts as a cushion. This device is known as air compressor pressure vessel.
The idea is to pump air through a valve in its upper head and then let the air reach an equilibrium with the water (normally at a point in the middle part of the tank, which is vertical). The problem is that I haven't been able to find the gas dissolution rate in the water. I have studied the Henry Law but that one is for static environments (like a closed can of Coke). In this case we have the pump constantly applying pressure to the water. Therefore, if air is not supplied constantly, it will be completely dissolved in water over time. I am looking for a formula that allows to measure this gas loss rate, for a specific gas, at a certain temperature, given a certain contact area and over a certain period of time.
Regards
Felipe
I am trying to calculate the gas loss rate in a pressure vessel, which is connected to a pipeline. The upper part of this cylindrical tank will be filled with air under pressure, and the lower part will be filled with the fluid pumped, which is normally water. The air will be compressed when the pressure in the fluid goes up and viceversa, preventing the pressure in the pipeline to rise or dip too much). In other words, the air acts as a cushion. This device is known as air compressor pressure vessel.
The idea is to pump air through a valve in its upper head and then let the air reach an equilibrium with the water (normally at a point in the middle part of the tank, which is vertical). The problem is that I haven't been able to find the gas dissolution rate in the water. I have studied the Henry Law but that one is for static environments (like a closed can of Coke). In this case we have the pump constantly applying pressure to the water. Therefore, if air is not supplied constantly, it will be completely dissolved in water over time. I am looking for a formula that allows to measure this gas loss rate, for a specific gas, at a certain temperature, given a certain contact area and over a certain period of time.
Regards
Felipe
RE: Gas dissolution rate in water
What you are describing has existed for generations as a pulsation bottle. The only difference is that the pulsation bottles have the air contained within a bladder that doesn't directly contact the pumped fluid. The reason that this solution has survived for many decades intact is that it works. Just pumping air into a vessel will not work because much more of the air will bubble through the pumped water than will ever dissolve in it.
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Gas dissolution rate in water
http://inspectapedia.com/water/Water_Tank_Air_Volu....
There is no equation that will give you the answer you seek.
RE: Gas dissolution rate in water
A.
RE: Gas dissolution rate in water
RE: Gas dissolution rate in water
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Gas dissolution rate in water
RE: Gas dissolution rate in water
A bladder makes up for these deficiencies. If for some reason a bladder type accumulator is not possible, then an oversized accumulator vessel and pressure controls with better response will help to minimise carryunder of air in the exit water stream.
RE: Gas dissolution rate in water
The key factor you seem to miss is that it should be the same water that is in the water below the air, at least for the first 100mm or so.
The key problem I have is the same as zuesfaber - if your inlet pressure into this vessel ever went below your air pressure when the level is at the minimum, or the whole volume is virtually air, then air will escape down the pipe.
Otherwise once the water in the vessel has equalized, then the dissolution rate will fall as most of the water is already saturated.
To avoid any of these issues, that's why bladdrrs are used, as most others have already pointed out.
If you're installing a piston, why would there be any contact or leakage?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Gas dissolution rate in water
He's pumping new water through the vessel continuously, The new water will not be saturated.
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Gas dissolution rate in water
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Gas dissolution rate in water
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Gas dissolution rate in water
A.
RE: Gas dissolution rate in water
There should be a level controller resetting the setpoint of the air side pressure controller if level drops below the low limit of the operating level range.
Also, the feed pipe for the water should dip down below the low level limit to reduce air entrainment in the water exit nozzle.