Submergible cryogenic pump with linear electromagnetic motor drive

Abstract

A fully submergible dual-action cryogenic pump has a housing configured to receive a liquid into the interior compartment when submerged in the liquid. The housing includes an interior compartment having an inner peripheral surface, a first end, and a second end. A free piston having a first end, a second end, and an outer peripheral surface is contained within the interior compartment. A first compression chamber is formed between the first end of the free piston and the first end of the interior compartment. A second compression chamber is formed between the second end of the free piston and the second end of the interior compartment. An electromagnetic drive is configured to reciprocate the free piston. A sealing area is formed by the outer peripheral surface of the free piston sealing with the inner peripheral surface of the interior compartment.

What is claimed is: 
     
         1 . A fully submergible dual-action cryogenic pump, comprising:
 a housing including an interior compartment, the housing configured to receive a liquid into the interior compartment when submerged in the liquid, the interior compartment including an inner peripheral surface, a first end, and a second end;   a free piston contained within the interior compartment of the housing, the free piston including an axis, a first end, a second end, and an outer peripheral surface;   a first compression chamber formed between the first end of the free piston and the first end of the interior compartment;   a second compression chamber formed between the second end of the free piston and the second end of the interior compartment;   an electromagnetic drive configured to reciprocate the free piston along the axis; and   a sealing area formed by the outer peripheral surface of the free piston sealing with the inner peripheral surface of the interior compartment between the first compression chamber and the second compression chamber.   
     
     
         2 . The fully submergible dual-action cryogenic pump of  claim 1 , wherein the free piston includes a length from the first end to the second end, and the sealing area is formed along substantially all of the length of the free piston. 
     
     
         3 . The fully submergible dual-action cryogenic pump of  claim 1 , wherein the outer peripheral surface of the free piston is configured to sealing area with the inner peripheral surface of the interior compartment without a piston sealing ring. 
     
     
         4 . The fully submergible dual-action cryogenic pump of  claim 1 , wherein no bushings are disposed between the free piston and the housing. 
     
     
         5 . The fully submergible dual-action cryogenic pump of  claim 1 , wherein:
 the housing includes an outer wall; and   the electromagnetic drive includes a plurality of electric coils disposed within the outer wall of the housing and encircling the axis of the free piston.   
     
     
         6 . The fully submergible dual-action cryogenic pump of  claim 1 , further comprising a one-way intake valve fluidly connected to the liquid when the housing is submerged in the liquid. 
     
     
         7 . The fully submergible dual-action cryogenic pump of  claim 6 , further comprising a primer pump configured to pump the liquid into the first compression chamber through the one-way intake valve when the housing is submerged in the liquid. 
     
     
         8 . The fully submergible dual-action cryogenic pump of  claim 1 , wherein the electromagnetic drive is also configured to rotate the free piston about the axis of the free piston. 
     
     
         9 . The fully submergible dual-action cryogenic pump of  claim 1 , wherein:
 the outer peripheral surface of the free piston includes a radius;   the inner peripheral surface of the interior compartment includes a radius; and   the radius of the outer peripheral surface of the free piston is between 0.01 micrometers and 2 micrometers less than the radius of inner peripheral surface of the interior compartment.   
     
     
         10 . The fully submergible dual-action cryogenic pump of  claim 1 , wherein one or more of the outer peripheral surface of the free piston and the inner peripheral surface of the interior compartment includes solid dry lubricants including one or more of molybdenum disulfide and sintered silicon carbide. 
     
     
         11 . The fully submergible dual-action cryogenic pump of  claim 1 , wherein one or more of the outer peripheral surface of the free piston and the inner peripheral surface of the interior compartment includes solid dry lubricants including one or more of tungsten(IV) sulfide and graphite. 
     
     
         12 . The fully submergible dual-action cryogenic pump of  claim 1 , further comprising a gas layer disposed between the outer peripheral surface of the free piston and the inner peripheral surface of the interior compartment. 
     
     
         13 . A fully submergible dual-action cryogenic pump system, comprising:
 a housing including an interior compartment, the housing configured to receive a liquid into the interior compartment when submerged in the liquid, the interior compartment including an inner peripheral surface;   a piston including an outer peripheral surface, an axis, and a length along the axis;   an electromagnetic drive configured to reciprocate the piston when the piston is contained within the interior compartment; and wherein
 a sealing area is formed by the outer peripheral surface of the piston sealing with the inner peripheral surface of the interior compartment when the piston is contained within the interior compartment. 
   
     
     
         14 . The fully submergible dual-action cryogenic pump system of  claim 13 , wherein the outer peripheral surface is disposed along a majority of the length of the piston. 
     
     
         15 . The fully submergible dual-action cryogenic pump system of  claim 13 , wherein the outer peripheral surface of the piston is configured to seal with the inner peripheral surface of the interior compartment without a piston sealing ring. 
     
     
         16 . The fully submergible dual-action cryogenic pump system of  claim 13 , further comprising a one-way intake valve configured to allow the liquid to flow into the interior compartment when the housing is submerged in the liquid. 
     
     
         17 . The fully submergible dual-action cryogenic pump system of  claim 16 , further comprising a primer pump configured to pump the liquid into the interior compartment of the housing through the one-way intake valve when the housing is submerged in the liquid. 
     
     
         18 . The fully submergible dual-action cryogenic pump system of  claim 13 , wherein the piston includes a magnetic portion disposed eccentrically with respect to the axis as measured in a plane orthogonal to the axis. 
     
     
         19 . The fully submergible dual-action cryogenic pump system of  claim 13 , wherein one or more of the outer peripheral surface of the piston and the inner peripheral surface of the interior compartment includes solid dry lubricants, the solid dry lubricants including one or more of molybdenum disulfide, sintered silicon carbide, tungsten(IV) sulfide, and graphite. 
     
     
         20 . A method of pumping a cryogenic liquid using a pump submerged in the cryogenic liquid, comprising:
 electromagnetically reciprocating a free piston enclosed within a housing of the submerged pump along an axis of the free piston;   allowing the cryogenic liquid to alternately flow into a first compression chamber inside the housing and into a second compression chamber inside the housing;   alternating between discharging the cryogenic liquid from the first compression chamber and from the second compression chamber; and   electromagnetically rotating the free piston about the axis of the free piston.