Helium and nitrogen reliquefying apparatus

Abstract

A cryogen boil-off gas re-liquefier adapted for retrofitting magnetic resonance instruments designed to exhaust vaporized helium. Means for recondensing helium and nitrogen boil off gasses to reduce operating cost of cryogenic systems.

1 . An apparatus comprising a
 vacuum vessel coupled to at least one flexible helium transfer line;   said vessel comprising at least one outer annulus; said transfer line comprising an outer insulation conveying bellows coupled to said vessel; an   inner insulation conveying bellows; said inner containing helium piping; said inner bellows coupled to a 77K can; said 77K can comprising at least one inner annulus;   said helium piping passing through said inner annulus and coupled to a vapor port and to a liquid port of a helium recondenser assembly.   
   
   
       2 . The apparatus of claim one wherein said bellows further comprises an a plurality of springs, and a plurality of spindles. 
   
   
       3 . The apparatus of claim one wherein said flexible helium transfer line comprises a helium transfer pipe insulated by a 77K heat shield and 300K heat shield, 
   
   
       4 . The apparatus of claim one wherein said recondenser assembly comprises a recondenser container or housing,
 a vapor port,   a liquid port, and a   recondenser.   
   
   
       5 . The apparatus of  claim 1  further comprising a cryogen refrigeration coldhead coupled to the bellows, said coldhead comprising a first flange coupled to said liquid nitrogen cooled can and a second flange coupled to said helium recondenser assembly. 
   
   
       6 . The apparatus of  claim 1  further comprising a flexible nitrogen transfer line coupled to said vessel. 
   
   
       7 . The apparatus of  claim 1  further comprising a cryogen pump whereby the liquid may be reintroduced to the cryostat independent of gravity flow. 
   
   
       8 . The apparatus of  claim 1  further comprising a system purge loop and a refrigeration balancing heater whereby slightly positive pressure is maintained over ambient air pressure. 
   
   
       9 . The apparatus of  claim 1  further comprising a plurality of helium transfer lines coupled to the helium recondenser assembly whereby a plurality of client cryostats may be served by one cryocooler. 
   
   
       10 . The apparatus of  claim 1  wherein said coldhead is a pulse-tube coldhead.