Facts about helium

One liter of liquid helium expands to 750 liters of helium gas under normal or also called standard conditions (1 bar, room temperature), when going through the boiling point of 4.2 K. The lambda point, the point where liquid helium gets superfluid, is at 2.2 K. The density of liquid helium at 1 bar and 4.2 K is 0.125 kg/l.

The picture illustrates the volume change of helium at different pressures and temperatures in a typical gas storage cylinder with 50 liters volume, a gas bag with 10 m³ volume (equals 10.000 liters) and a transport dewar with 100 liters volume, which is only filled with 12,5 liters of liquid helium.


What makes helium so unique?

  • Rare on earth, but 2nd most abundant element in the universe after hydrogen
  • Forms in the earth crust as a result of the radioactive decay of He2+
  • Greatest amounts can be found in natural gas (between 0.3 and 2.7%)
  • Two stable isotopes exist: 4He and 3He
  • Named after Helios, the Greek god of the sun

Helium applications

  • Helium oxygen mixtures (80:20) in medicine
  • Gas for professional divers ("Trimix", "Heliox")
  • Food industry (E939)
  • Helium balloons
  • Welding
  • Inert(protecting) gas
  • Carrier gas for gas chromatography
  • Leak testing
  • Lasers (He-Ne laser, He-Cd laser)
  • Pressurized gas instead of air (Formula 1)
  • Cryogenics

Helium consumption

Relative amounts of helium consumed by various uses in the United States during 2011. The graph is from Geology.com and uses data from the USGS. It shows that nearly 1/3 of the overall helium in the US was used in cryogenic form, for example as liquid helium for cooling temperatures as low as 4.2 K and below.

Helium consumption worldwide in million cubic meters (source)


Why recycle helium?

Helium is the most common element in space. However here on earth it can only be found as a small fraction in some natural gas deposits.

Once released in air it diffuses to the stratosphere and becomes unavailable.

Recycling helium:

Saves costs – Running cost of recovery plant is much less than purchasing liquid helium.

Makes independent of external suppliers - Helium is always available on site.

Helps control the quality – each new batch of external Helium might be contaminated with hydrogen, which leads to malfunction of cryostats.

Helps protect the environment – The finite resource helium is preserved.


Helium recovery layout tool

Getting the dimension of your helium recovery right will help you maximize the recovery efficiency of your liquid helium recovery plant. This tool will give you a first idea about which recovery you should consider with your preconditions. Simply fill in the amount of liquid helium (LHe) in liters that you transfer during your highest transfer to get the maximum recovery system configuration you need. Also fill in the losses per transfer in liters. They typically range from 20 – 30% of the overall transferred liquid helium.

Please fill out all fields!

Liquid helium per transfer (in L)

Losses per transfer (in L)

Transfer time in min.

Stored LHe

Medium Pressure Recovery Configuration:

Number of gas tanks:
(1000L)

Liquid helium gas losses in l/min:

High Pressure Recovery Configuration:

Balloon size:

Number of gas bottles:
(50L, 200bar)

For a good estimate of your situation you also need to enter the time it takes to fill your cryostats with liquid helium (transfer time) and the amount of liquid helium you want to store as gas inside your recovery system. The indicated result will be the suggested number of helium gas tanks with 1000 liters volume, pressurized up to 5 bar. At a value above 5, we suggest using a high pressure recovery system (HPR), as the footprint of a corresponding medium pressure recovery system (MPR) would be much larger. If this is not desired, we suggest reconsidering the amount of stored liquid helium as gas.

If a helium gas loss is indicated as negative value, then it can be considered a true loss. A positive value means that the helium gas flow can be collected, if the number of gas tanks is equal to or higher than the number calculated.

For the high pressure recovery the values calculated are the gas bag size in cubic meters and the number of 50 liters gas bottles (pressurized with 200 bar).
All calculations are supposed to help get an idea of which recovery solution might be best for your requirements. Please contact us for further information and full configuration setup.


Return of investment tool

The Return on Investment (ROI) tool helps you estimate the point when, apart from aspects like supply safety and sustainability, the purchase of a helium recovery plant pays off.

If you press calculate the different costs involved in a helium recovery are estimated from your input values. The calculations are shown for all three different recovery solutions, direct recovery – DR, medium pressure recovery – MPR and high pressure recovery – HPR.

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Electricity costs in €/kwh

Liquid helium costs in €/LHe

Liquid helium consumption in LHe/year

DR MPR HPR
Electricity costs (€/year)
Maintenance costs (€/year)
Compensation costs (€/year)
Overall yearly costs (€/year)
Costs to buy LHe (€/year)
Return of Investment

Based on the specified power consumption of the equipment involved and its estimated running time in the different configurations, electricity costs are calculated in Euros per year. Maintenance costs are fix costs that depend on the configuration, but can change in reality according to the dimension of the recovery plant. Compensation costs are connected to the losses which cannot be collected by the recovery plant and where liquid helium has to be bought to keep the number of liters constant. The DR has a recovery efficiency of approx. 70%, which is equal to about 30% of losses which have to be compensated. The MPR recovers around 95% (approx. 5% losses), and the HPR recovers approx. 99% (1% losses).


How is helium recycled?

The typical small-scale helium recovery and liquefaction plant works with the following processing steps:

 

Collection

Helium gas is collected from the instrument. Consider the type of the recovery kit used and how to protect the equipment from the influence of the recovery solution.

Storage

Direct recovery
No storage - single instrument

Medium Pressure
Helium is stored in steel tanks at 5 bar.

High Pressure
Helium is buffered in a balloon and stored in steel cylinders at 200 bar.

Purification

Inline
Purifiers like dryers and getters

Liquid nitrogen trap
Adsorption on charcoal at 77 K

Cryogenic purifier
Works at 10-25 K - automated solution

Liquefaction

Compact, portable liquefier utilizing a Gifford-McMahon cryocooler.
Produces 10-30 liters of liquid helium per day.

 


Storage configurations

Direct recovery

A - lab-size liquefier
B - helium compressor
C - recovery pressure controller
D - power box
X - cryogenic instrument

Pro:
  • Easy to install and use
  • Minimal space required
  • Less expensive
  • Upgradable to MP or H

 

Contra:
  • Limited recovery rate (70-80%) due to transfer loss

Medium pressure recovery

A - lab-size liquefier
B - helium compressor
C - booster hub with buffer tank
D - purifier
E - storage tanks
F - recovery pressure controller
X - cryogenic instrument

Pro:
  • Ideal for one or two instruments
  • High efficiency (>95%)

 

Contra:
  • Limited storage capacity

High pressure recovery

A - lab-size liquefier
B, D - helium compressors
C - cryogenic purifier
E - gas bag with controller
F - high-pressure compressor
G - storage cylinder bundle
H - recovery pressure controller
X - cryogenic instrument(s)

Pro:
  • Versatile, customized and scalable
  • Applicable for any type of helium consumers
  • Very high efficiency (>98%)

 

Contra:
  • Comparatively higher costs
  • Requires a lot of space (for helium balloon)

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