Cryogenic Gas Circulators

Barber-Nichols Inc. (BNI) is the world leader in the design and production of centrifugal, hermetic cryogenic gas circulators. BNI builds circulators that process hydrogen, nitrogen, natural gas, helium, and more at temperatures down to 5 K (-450 °F). Hermetic designs are extremely desirable for cryogenic applications, because they eliminate the need for mechanical shaft seals and as a result, completely eliminate cryogen leakage. Additionally, hermetic compressors eliminate air infiltration and are inherently explosion proof.

  • High-speed designs and the use of variable frequency drives result in efficient operation across a wide variety of head/flow conditions.
  • Single-shaft, direct-drive designs are highly reliable due to their simplicity and are extremely stable throughout their entire operating range.
  • Low vapor pressure, rolling element, and grease-packed or proprietary dry lubricated bearings provide long term, reliable service without contaminating the process fluid.
  • Gas (foil) bearings utilize the cryogen to rotate on a gas film and allow very high speed operation to maximize efficiency and greatly increase life. 
  • Friction-free magnetic bearings eliminate wear items and allow machines to operate at extremely high speeds for many years without maintenance.
  • User-friendly designs allow the compressor to be serviced without breaking the cold box vacuum.
Model BNHeP-11-000 Cryogenic Helium Circulator   Model BNHeP-11-000 Cryogenic Helium Circulator In RHIC

Model BNHeP-11-000 Cryogenic Helium Circulator in
Brookhaven National Laboratory's Relativistic Heavy Ion Collider

 BNI Designs & Produces Cold Gas Compressors for the:

  • Circulation of Hot & Cold Nitrogen Gas in Space Simulation Chambers.
  • Circulation of Cryogenic Helium for the Cooling of Superconducting Magnets.
  • Compression of Boil-Off-Gas at Maritime LNG Receiving Terminals.

Oak Ridge National Laboratory Supercritical Cryogenic Hydrogen Circulator Case Study

Model BNHP-24-000 Supercritical Cryogenic Hydrogen CirculatorBNI designed and produced a supercritical cryogenic hydrogen circulator for the Oak Ridge National Laboratory's (ORNL) Spallation Neutron Source (SNS). The SNS produces a high intensity, cold neutron beam used to investigate how materials are assembled at the subatomic level.

The SNS utilizes a hydrogen loop system to cool the neutrons; it begins operation at room temperature and then cools down to 17 K (-429 °F). A Variable Frequency Drive was used because the circulator's speed adjusts inversely proportional to the fluid density. It begins operation at 60,000 rpm and gradually slows down to 15,000 rpm when the SNS reaches its operating temperature. When the compressor begins operation at room temperature, it circulates 6m3/hr (13.4 ft3/min), and maintains system pressure at 0.27 bar (3.92 psi). When the system reaches its 17 K operating temperature, the hydrogen is supercritical and the compressor is processing 1.02 lpm (0.27 gpm), and is maintaining system pressure at 1.00 bar (14.50 psi). Because high reliability and a long life were paramount on ORNL's list of requirements, BNI decided to utilize friction-free magnetic bearings rather than ball bearings.

NASA Propellant Densification Case Study

Launch Vehicle Propoellant Densification SystemMany of today's large rocket engines utilize Liquid Oxygen (LOX) and Liquid Hydrogen (LH2) as engine propellants. Engineers at Rockwell Space Systems discovered three revolutionary benefits that can be realized when propellants are subcooled, thereby increasing their densities.

First, when propellant densities are increased, their volumes decrease by 7-15%. As a result, smaller propellant tanks can be used. Second, propellant tank walls can be thinner and lighter because subcooled propellants have an extremely low pressure. Finally, subcooled propellants allow launch vehicle designers to utilize smaller, lighter turbopumps. Subcooled propellants have a higher available Net Positive Suction Head (NPSH); therefore, turbopumps can operate at a higher speed without cavitating. Because it costs about $10,000 USD per pound to place a launch vehicle into low earth orbit, propellant densification results in substantial cost savings and the ability to launch greater payloads. BNI designed and built the intricate series of pumps and cryogenic gas compressors required for a prototype system. System tests at NASA's Lewis Plumbrook Field Station yielded positive results. BNI then designed and built full size systems for both LOX and LH2 . The full size systems were tested at NASA's Glenn Research Center.

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