Helium is a non-renewable resource mined alongside natural gas from large pockets beneath the earth’s crust. It is a critical element in numerous industries including welding, medical imaging (MRI), semiconductor chip manufacturing for phones and computers, as well as scientific research including nuclear magnetic resonance (NMR). Due to its light weight, as helium is consumed in these applications, it is lost to the atmosphere. As helium supplies on earth dwindle, shortages have threatened industries reliant on helium. In recent years, helium recovery and recycling has become critical to preserve the remaining helium supply on earth.

Many critical industries are dependent on the planet’s dwindling supply of helium.

In 2021, the University of Delaware NMR Facility (with funding from the National Institutes of Health 3R01GM026643-41S1) installed a helium recovery system. This system collects helium as it boils off from inside the NMR magnets. (For more information on why we use liquid helium in NMR, visit NMR For Everyone.) The helium is collected in a large storage bag, then compressed into storage tanks. With a CryoMech/Bluefors helium recovery system, we are able to then purify and re-liquefy the helium right in our lab, and refill the NMR magnets with the recycled helium. With this system, we are able to recover more than 90% of the helium we consume!

Helium is captured as it boils off inside the NMR magnets and travels through wall-mounted manifolds at each magnet to a central collection bag. While the helium that boils off on a constant basis quickly reaches room temperature, when the magnets are refilled with liquid helium, the manifolds monitor the flow of helium, and warm up the very cold gas that comes out during these refills.
Helium from all 8 magnets is collected in a centralized storage bag (top), then compressed for storage in gas tanks (lower right). From there, it is purified and re-liquefied.
Helium is purified by passing the gas through a very cold membrane (57 K, -357°F, -216°C). Helium remains a gas, while other contaminants such as nitrogen and oxygen condense on the membrane. Figure prepared in BioRender.
Helium gas is converted to liquid by condensation on a coldhead as it enters the liquification dewar. Figure from Chao Wang 2009 J. Phys.: Conf. Ser. 150 012053.
Finally the liquid helium (4K, -420°F, -269°C) is transferred to a portable dewar and the magnets are refilled.

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