Cryogenic pump

Abstract

A pump for pumping a cryogenic liquid includes a pump housing defining an elongated cylinder. An elongated piston slides within the cylinder so that an intermediate fluid chamber, that is configured to receive an intermediate fluid, is defined within the cylinder adjacent to a first end of the piston and a fluid pumping chamber is defined within the cylinder adjacent to a second end of the piston. The fluid pumping chamber includes an inlet and an outlet. The pump housing is positioned within a sump. The sump is configured to receive and submerge a portion of the pump housing within the cryogenic liquid and to provide cryogenic liquid to the inlet of the pumping chamber for pumping. A sump jacket surrounds the sump so that a sump insulation space is defined therebetween. A pump jacket surrounds the pump housing so that a pump insulation space is defined therebetween.

What is claimed is: 
     
         1 . A pump for pumping a cryogenic liquid comprising:
 a. a pump housing defining an elongated cylinder;   b. an elongated piston slidably positioned within the cylinder so that an intermediate fluid chamber that is configured to receive an intermediate fluid is defined within the cylinder adjacent to a first end of the piston and a fluid pumping chamber is defined within the cylinder adjacent to a second end of the piston, said fluid pumping chamber including an inlet and an outlet;   c. a sump within which the pump housing is positioned, said sump configured to receive and submerge a portion of the pump housing within the cryogenic liquid and to provide cryogenic liquid to the inlet of the pumping chamber for pumping;   d. a sump jacket surrounding said sump so that a sump insulation space is defined therebetween;   e. a pump jacket surrounding said pump housing so that a pump insulation space is defined therebetween.   
     
     
         2 . The pump of  claim 1  further comprising a drive system for cyclically providing intermediate fluid to the intermediate fluid chamber so that the piston is actuated to pump the cryogenic liquid from the pumping chamber. 
     
     
         3 . The pump of  claim 1  wherein the piston moves between a top dead center position and a bottom dead center position and wherein a bottom end of the pump jacket is generally coplanar with the second end of the piston when the piston is in the top dead center position. 
     
     
         4 . The pump of  claim 1  wherein a heath transfer path length defined as a difference between a length of the piston and a stroke length of the piston between top dead center and bottom dead center positions is approximately six inches or more. 
     
     
         5 . The pump of  claim 4  wherein a ratio of a diameter of the pump housing cylinder to the longitudinal length of the pump housing cylinder is approximately 8% or less. 
     
     
         6 . The pump of  claim 1  wherein a heath transfer path length defined as a difference between a length of the piston and a stroke length of the piston between top dead center and bottom dead center positions is approximately twelve inches or more. 
     
     
         7 . The pump of  claim 6  wherein a ratio of a diameter of the pump housing cylinder to the longitudinal length of the pump housing cylinder is approximately 8% or less. 
     
     
         8 . The pump of  claim 1  wherein the cryogenic liquid is hydrogen liquid 
     
     
         9 . The pump of  claim 1  wherein the intermediate fluid is propane. 
     
     
         10 . The pump of  claim 1  wherein the intermediate fluid is 1-butene. 
     
     
         11 . The pump of  claim 1  wherein the piston includes a polytetrafluoroethylene coating that is molded to provide circumferential seals. 
     
     
         12 . The pump of  claim 11  wherein the piston includes a core upon which the coating is placed wherein the core includes a cavity. 
     
     
         13 . The pump of  claim 1  wherein the pump insulation space and the sump insulation space includes vacuum insulation. 
     
     
         14 . The pump of  claim 13  further comprising a neck jacket joining the sump to the pump jacket so as to suspend the pump jacket within the sump, said neck jacket defining a vacuum space that is open with respect to the pump insulation space and sump insulation space.