Comment by hrmtst93837
11 hours ago
Helium for party balloons is low grade and not pure enough for chip fab use, so stacking up birthday tanks won't keep TSMC running. Industrial grade helium has a restricted and oddly international supply chain thanks to regulation and a few weirdly-placed depots. The US 'helium stockpile' isn't really a menu you can just order from when a factory across the planet runs dry, especially if offtakes and logistics are tied up by decade-old government contracts. If you want to see supply chain fragility, try pricing MRI-grade helium after a shutdown and watch everyone in medical procurement panic quitely.
Isn't Helium one of the easiest elements to purify? Just cool it below 14 Kelvin, which will make everything else freeze out. Collect the remaining liquid, which should be pure Helium.
14 kelvin is not easy to achieve at scale + after that, you need to keep it pure.
Apparently 14 K cooling is not used even up to 5N or 6N purity, commercial large-scale sources use various other tricks to remove the other gases. They do cool the input gas down to liquid nitrogen temperatures as one of the first steps.
My point is that there's "maximally efficient / profitable" versus "can be made available as an emergency alternative".
Cooling to 14 K isn't the cheapest option, but it has very low complexity. You can "simply" pressurise the source gas, cool it to room temperature through an ordinary heat exchanger, then allow it to expand. The only issue is that if you do this naively, the expansion nozzle will get clogged with ice.
Obviously, this wastes a lot of Helium, but we have lots of it. If what's needed is high purity Helium, then throwing away even 90% to get 10% that's 6N pure should be no problem for an industrial nation.
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after what kind of shutdown?
If the helium gets warm, you have to vent it outside before it goes kaboom from the pressure.
https://radiology.ucsf.edu/patient-care/patient-safety/mri-s...
Damn, that's intense:
> If the scan room door is closed when a quench occurs and helium escapes into the scan room, the depletion of oxygen causes a critical increase in pressure in the room compared with the control area. This produces high pressure in the scan room, which may prevent opening of the door. If this should happen, the glass partition between the scan and control rooms should be broken to release the pressure. The scan room door can then be opened as usual and the patient evacuated. In such a case the patient should be immediately evacuated and evaluated for asphyxia, hypothermia and ruptured eardrums.
Most MRIs vent their helium in an emergency shutdown. https://medprotech.de/en/what-is-an-mri-quench/