Cryogenic Gas Circulators

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

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 a 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.

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

BNI 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 is capable operation over a wide range of speeds from hundreds of RPM up to 60,000 rpm while the hydrogen changes temperature from room down to 17 K.  Friction-free magnetic bearings were used rather than ball bearings to meet high reliability and long life requirements.

NASA Propellant Densification

Many 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 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.

 

BNCP-66-000 Cryogenic Natural Gas Blower System

BNI has developed the next generation cryogenic natural gas blower.  This simple design utilizes a Variable Frequency Drive (VFD) to operate a high-speed motor that direct-drives a centrifugal impeller.  It utilizes thermal isolating features that allow for rapid temperature swings from ambient down to cryogenic temperatures. A sophisticated control system allows the customer top operate the blower remotely to meet numerous operating points needed.  These blowers can be used for cryogenic natural gas, nitrogen, hydrogen and other gases.

BNCP-21 Nitrogen Gas Blower

The BNCP-21 blower is a high-speed gas circulator used in Space Simulation Chambers.  Nitrogen gas is circulated to a shroud inside the chamber and typically alternates between 150 C and -185 C (300 F and -300 F) for months at a time to simulate the temperature changes a satellite endures as it orbits in front of and behind the earth.

These relatively small circulators have a high-speed motor direct-driving an impeller on a single shaft with high-precision ball bearings.  Stable and reliable operation is possible over a wide range of speed utilizing a variable frequency drive (VFD) thus producing a large performance range.  The circulator is hermetically sealed and has a fluid jacket for circulation of water/glycol to cool the power-dense motor and actually warm the lower bearing during cryogenic operation.  This circulator can be serviced without being disconnected from the nitrogen gas plumbing.  BNI has produced blowers for space simulation chambers used around the world for clients such as Air Liquide, Angelantoni, the Indian Space Research Organization (ISRO), Lockheed Martin, NASA and Space Systems Loral.