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temp of compressed nitrogen gas 2
- Thread starter GenB
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As IsrealKK notes, compressed nitrogen at 5500psi can be just about any temperature you want it to be, within reason. Want it at 0degF? Put it in a fridge. Want it at 82degF? Put it next to my desk. Want it at 200degF? Put it in front of a heater.
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Montemayor
Chemical
GenB:
Hard data? Compressed gases like Oxygen, Nitrogen, Hydrogen, and air are stored and distributed at ambient temperatures and pressures up to and including 5,000 psig everyday. This was - and still is - done in the compressed gas industry. Steel cylinders and "tubes" are used for this purpose.
I don't know what your engineering experience or training is, but you don't seem to have the knowledge or awareness of compressible fluids. Either that, or you're not communicating your question(s) well.
In the normal production of cryogenics, stuff like gaseous Oxygen and Nitrogen are literally "pumped" into steel cylinders. What I mean is that, contrary to what israelkk describes, there is no adiabatic gas compression taking place (nor is a gas compressor used). The liquid cryogen fluid is pumped at the desired pressure (usually 2,000 - 3,000 psig) and vaporized on its route towards the ultimate steel cylinders by a heat exchanger that is cooling the in-coming air feed. The only heat generated by this process is that of the expanding steel walls of the cylinders - but this is easily dissipated to the surrounding atmosphere before the termination of the "fill". The result is a steel cylinder filled with gaseous Nitrogen and at 3,000 psig.
Hard data? Compressed gases like Oxygen, Nitrogen, Hydrogen, and air are stored and distributed at ambient temperatures and pressures up to and including 5,000 psig everyday. This was - and still is - done in the compressed gas industry. Steel cylinders and "tubes" are used for this purpose.
I don't know what your engineering experience or training is, but you don't seem to have the knowledge or awareness of compressible fluids. Either that, or you're not communicating your question(s) well.
In the normal production of cryogenics, stuff like gaseous Oxygen and Nitrogen are literally "pumped" into steel cylinders. What I mean is that, contrary to what israelkk describes, there is no adiabatic gas compression taking place (nor is a gas compressor used). The liquid cryogen fluid is pumped at the desired pressure (usually 2,000 - 3,000 psig) and vaporized on its route towards the ultimate steel cylinders by a heat exchanger that is cooling the in-coming air feed. The only heat generated by this process is that of the expanding steel walls of the cylinders - but this is easily dissipated to the surrounding atmosphere before the termination of the "fill". The result is a steel cylinder filled with gaseous Nitrogen and at 3,000 psig.
GenB,
Try the question with a little more info.
Has the compressed N2 just been compressed? Is the N2 "as delivered" from the truck? Are you venting and the N2 cold? They may seem like silly questions, but it would help understand where you are coming from.
Try the question with a little more info.
Has the compressed N2 just been compressed? Is the N2 "as delivered" from the truck? Are you venting and the N2 cold? They may seem like silly questions, but it would help understand where you are coming from.
Montemayor
I have to disagree with you. We use a booster from HASKEL co. to compress Nitrogen and Helium from a 2000 psi 40liter bottles into smaller volume pressure vessels up to 15000psi. The gas temperature rises during the process which is definitely polytropic process. I used the adiabatic term just as an example.
To insure that the vessels will be correctly filled we weigh them before and during the filling process or use a slow flow rate to minimize the temperature change.
By knowing the gas weight and the internal volume of the vessel we know what will be the pressure when the gas is cooled to ambient temperature.
I have to disagree with you. We use a booster from HASKEL co. to compress Nitrogen and Helium from a 2000 psi 40liter bottles into smaller volume pressure vessels up to 15000psi. The gas temperature rises during the process which is definitely polytropic process. I used the adiabatic term just as an example.
To insure that the vessels will be correctly filled we weigh them before and during the filling process or use a slow flow rate to minimize the temperature change.
By knowing the gas weight and the internal volume of the vessel we know what will be the pressure when the gas is cooled to ambient temperature.
Montemayor
Chemical
israelkk:
I don't disagree with you that you are compressing N2 and He, using a compressor and realizing a definite temperature increase. This is pure and elementary thermo that can easily be seen on any Mollier diagram.
The normal way that I've filled literally hundreds of thousands of compressed gas cylinders with pure N2 at a pressure of 2,500 - 3,000 psig is not by using a gas compressor but rather, by using a LIQUID CRYOGENIC PUMP. The pump delivers Liquid Nitrogen (LIN) at the designated discharge pressure and passes it through a heat exchanger, where the liquid is vaporized with incoming feed air to the air separation cold box. I can guarantee you that you will see no adiabatic heat of compression when you pump a liquid. And you certainly don't see it at the N2 filling manifold. All you can detect is the heat of the expanding ("bloating") steel cylinder.
So little is the temperature increase from ambient that we never weighed or metered any N2 flow into the cylinders and yet each cylinder held the allotted nominal 250 Ft3 of N2 every time we disconnected it from the manifold. This is still the normal way to fill gas cylinders and distribute them. I've also used reciprocating gas compressors - 4 & 5 stages - to compress and fill Oxygen and Nitrogen cylinders. But that's another method, and one little used today. In that method more energy is consumed and after coolers are required to remove the heat of compression from each stage - especially the last one. I don't know of any one doing this industrially today. The most economical and cost effective way to fill high pressure industrial gas cylinders is to pump the fluid as a cryogen liquid (as I've described above) and vaporize it before it reaches the cylinder.
I don't disagree with you that you are compressing N2 and He, using a compressor and realizing a definite temperature increase. This is pure and elementary thermo that can easily be seen on any Mollier diagram.
The normal way that I've filled literally hundreds of thousands of compressed gas cylinders with pure N2 at a pressure of 2,500 - 3,000 psig is not by using a gas compressor but rather, by using a LIQUID CRYOGENIC PUMP. The pump delivers Liquid Nitrogen (LIN) at the designated discharge pressure and passes it through a heat exchanger, where the liquid is vaporized with incoming feed air to the air separation cold box. I can guarantee you that you will see no adiabatic heat of compression when you pump a liquid. And you certainly don't see it at the N2 filling manifold. All you can detect is the heat of the expanding ("bloating") steel cylinder.
So little is the temperature increase from ambient that we never weighed or metered any N2 flow into the cylinders and yet each cylinder held the allotted nominal 250 Ft3 of N2 every time we disconnected it from the manifold. This is still the normal way to fill gas cylinders and distribute them. I've also used reciprocating gas compressors - 4 & 5 stages - to compress and fill Oxygen and Nitrogen cylinders. But that's another method, and one little used today. In that method more energy is consumed and after coolers are required to remove the heat of compression from each stage - especially the last one. I don't know of any one doing this industrially today. The most economical and cost effective way to fill high pressure industrial gas cylinders is to pump the fluid as a cryogen liquid (as I've described above) and vaporize it before it reaches the cylinder.
cryotechnic
Chemical
I agree with Montemayor. Filling cylinders the way he describes is the most efficient way to do.
Filling them an other way, you have extra costs due to extra energy consumed with compressors and inter/after coolers.
In our air separation plant, we don't fill cylinders but we have pipeline customers. In the old plants, the oxygen and nitrogen exit the coldbox in a gasous state, and we compress it in a compressor.
In our newer plants, the products are pumped as liquid to the designated pressure and then vaporised in the heat exchangers by the incoming air.
This is must more efficient. (and safer, we don't need a oxygen compressor)
We used to fill 1 krypton cylinder every 8 hours, filling pressure was 180barg, 50 liters. The Oxygen/krypton mixture was pumped by an one stage reciprocating pump to the designated pressure. Then the liquid was evaporated by an aircooled evaporator. By the time the cylinder was completly filled, the cylinder had become more than hand warm due to the compression heat.
Ofcourse the cylinder cooled down to ambient temperature.
GenB, please give more info in your questions, that's easier for us to answer.
Cryotechnic
"Math is the ruler of your potential succes...."
Filling them an other way, you have extra costs due to extra energy consumed with compressors and inter/after coolers.
In our air separation plant, we don't fill cylinders but we have pipeline customers. In the old plants, the oxygen and nitrogen exit the coldbox in a gasous state, and we compress it in a compressor.
In our newer plants, the products are pumped as liquid to the designated pressure and then vaporised in the heat exchangers by the incoming air.
This is must more efficient. (and safer, we don't need a oxygen compressor)
We used to fill 1 krypton cylinder every 8 hours, filling pressure was 180barg, 50 liters. The Oxygen/krypton mixture was pumped by an one stage reciprocating pump to the designated pressure. Then the liquid was evaporated by an aircooled evaporator. By the time the cylinder was completly filled, the cylinder had become more than hand warm due to the compression heat.
Ofcourse the cylinder cooled down to ambient temperature.
GenB, please give more info in your questions, that's easier for us to answer.
Cryotechnic
"Math is the ruler of your potential succes...."
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