Discussion
Something I spent ages on the net trying to find an answer to.
Friend thinks it s liquified before it is piped, I think it is sent in natural form, do they have pumps along the way or is the pipe built up hill or what?
Here is another question for clever people if gas was liquified, would you be able to move more of it or would it flow quicker in natural form?
Friend thinks it s liquified before it is piped, I think it is sent in natural form, do they have pumps along the way or is the pipe built up hill or what?
Here is another question for clever people if gas was liquified, would you be able to move more of it or would it flow quicker in natural form?
Edited by Oliver Hardy on Monday 12th September 15:51
Liquid natural gas is extremely cold (-162 ° C). It’s all right for insulated storage to cover peak demand and for bulk tanker transport, but it doesn’t lend itself well to pipeline transport. Not at any real distance at least.
The big national gas pipe network pumps pressurised natural gas at around ~85 psi I believe. A network of regional pumping stations (gas turbine powered of course) keeps the pressure up. Domestic gas pressure is only about 0.3 psi.
The big national gas pipe network pumps pressurised natural gas at around ~85 psi I believe. A network of regional pumping stations (gas turbine powered of course) keeps the pressure up. Domestic gas pressure is only about 0.3 psi.
The gas pipeline I was involved with had a max operating pressure of 90 bar.
However if you looked at the actual pressure it would start higher at the export compressors of the terminal, then drop steadily until the first compressor station. The profile would repeat until the pressure was deliberately reduced to allow transfer to other pipeline systems or national networks.
So, in summary, it was always a gas.
However if you looked at the actual pressure it would start higher at the export compressors of the terminal, then drop steadily until the first compressor station. The profile would repeat until the pressure was deliberately reduced to allow transfer to other pipeline systems or national networks.
So, in summary, it was always a gas.
"Gas" in the domestic networks is always in the gaseous state.
For long distance commercial transport via pipelines it will also be in the gaseous state
Where pipelines are not viable for commercial transport... so from say West Africa to the UK.... it will be moved as LNG in tankers. This requires an LNG plant at one end & a regas terminal at the other. An LNG plant simplistically chills & compresses the gas until it achieves a liquid state through using rather big compressors, whilst a regas terminal allows the compressed gas to expand back to gaseous state in a controlled manner (South Hook in Pembroke is the biggest example of this in Europe)
It all sounds very simple but particularly in the case of pipelines it can be a lot more complicated than it sounds to just stick stuff in one end of a pipe & get it out the other! Get the balance of temperature & pressures wrong hydrates (similar to ice) form & the line blocks. Pipeline engineers seems to be paid rather good money
For long distance commercial transport via pipelines it will also be in the gaseous state
Where pipelines are not viable for commercial transport... so from say West Africa to the UK.... it will be moved as LNG in tankers. This requires an LNG plant at one end & a regas terminal at the other. An LNG plant simplistically chills & compresses the gas until it achieves a liquid state through using rather big compressors, whilst a regas terminal allows the compressed gas to expand back to gaseous state in a controlled manner (South Hook in Pembroke is the biggest example of this in Europe)
It all sounds very simple but particularly in the case of pipelines it can be a lot more complicated than it sounds to just stick stuff in one end of a pipe & get it out the other! Get the balance of temperature & pressures wrong hydrates (similar to ice) form & the line blocks. Pipeline engineers seems to be paid rather good money
The main pipelines work at the pressure stated above 80-90 bar. There is substantial (yet relatively easy) thermodynamics to confirm this is the most efficient value. At lesser pressures, a problem called “sonic choking” occurs where the boundary layer builds up to be so thick it chokes the flow of the pipe. https://en.wikipedia.org/wiki/Choked_flow
The gas is usually clean i.e., it is just methane (CH4) and nothing else. Certainly, no condensate/ hydrates etc…
If it was liquified, much energy is required in liquifying it, a great deal of insulation would be required to keep it cold, and then it requires turning back into gas at the other end. This would cost a fortune.
If its “straight out of the well” gas, then that’s a different matter as it comes with a whole host of other stuff. Moisture, “fines” (tiny bits of rock strata) and loads of light aromatics, pentane, hexane, heptane, octane, nonane, decane, as well as nasties like hydrogen sulphide which eats stainless steel a treat. All these constituents vary from well to well, and also to a lesser extent with time for the same well.
Designing a high-speed axial compressor which can process all these in one go with belches of condensate coming through was a challenge. I could bore for Britain on this one…
The gas is usually clean i.e., it is just methane (CH4) and nothing else. Certainly, no condensate/ hydrates etc…
If it was liquified, much energy is required in liquifying it, a great deal of insulation would be required to keep it cold, and then it requires turning back into gas at the other end. This would cost a fortune.
If its “straight out of the well” gas, then that’s a different matter as it comes with a whole host of other stuff. Moisture, “fines” (tiny bits of rock strata) and loads of light aromatics, pentane, hexane, heptane, octane, nonane, decane, as well as nasties like hydrogen sulphide which eats stainless steel a treat. All these constituents vary from well to well, and also to a lesser extent with time for the same well.
Designing a high-speed axial compressor which can process all these in one go with belches of condensate coming through was a challenge. I could bore for Britain on this one…
I remember the gas pipeline being constructed from South Hook in Milford Haven, across Wales. There are markers along it’s route. Otherwise you wouldn’t know it was there underground. Tankers bring it in to the dedicated terminal. A significant percentage of UK gas comes in by the route. About 12 years ago about 30% if I remember correctly. I went to the Port Authority to see the set-up. Similar to air traffic control managing shipping in the Haven. I remember when there were several big refineries there too. Watching supertankers going there from a hilltop many miles away across Carmarthen Bay, Lundy in the distance with a massive tanker crossing between. Just one refinery now. Also talk of Hydrogen production in the future for the area.
To follow on from this I thought one of the issues with hydrogen was it was difficult to contain in a car fuel cell tank. Is that due to being under high pressure?
The governments fantasy of piping hydrogen thorough the gas mains to your house could only work if at 0.3 psi it wont escape.
The governments fantasy of piping hydrogen thorough the gas mains to your house could only work if at 0.3 psi it wont escape.
Aeronautical charts mark the locations of permanent Gas Venting Sites. Severe turbulence and power fluctuations in turbine engines could be experienced over gas during venting of natural (methane) gas under high pressure.
https://www.caa.co.uk/commercial-industry/airspace...
https://www.caa.co.uk/commercial-industry/airspace...
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