Cryogenic fluid pump system and method of pumping cryogenic fluid

A cryogenic pump system which comprises:

• a) a source of cryogenic fluid liquid at a cryogenic temperature;
• b) a cryogenic fluid-receiving container to receive cryogenic fluid liquid from the source of cryogenic fluid;
• and
• c) a cryogenic pump which comprises:
• i) a pump body with a hollow cylinder, an inlet conduit, an inlet port, an outlet conduit and an outlet port, the inlet conduit connected to the source of cryogenic fluid and the outlet conduit connected to the cryogenic fluid-receiving container;
• ii) a pump piston adapted for reciprocating movement within the cylinder between a first chamber to receive cryogenic fluid through the inlet port during an induction stroke of the piston, and a second chamber to discharge cryogenic fluid through the outlet port during a discharge stroke of the piston;
• iii) means to drive the pump piston within the cylinder at a relatively constant velocity to generate essentially steady state cryogenic fluid flow and to reduce heat generation and the production of cryogenic fluid vapor;
• and
• iv) the first and second chambers having sufficiently large displacement volume:
• (a) to remove vapor from the cryogenic fluid during the induction strokes at a rate faster than the liquid cryogenic fluid can vaporize in the inlet conduit;
• (b) to prime itself starting from an atmospheric, non-cryogenic temperature;
• and
• (c) to cool the pump to a cryogenic temperature.

A method of pumping a cryogenic fluid from a source of cryogenic fluid at a cryogenic temperature into a cryogenic fluid-receiving container, which method comprises:

• a) providing a positive displacement, cryogenic pump having:
• i) a pump body with a hollow cylinder, an inlet conduit, an inlet port, an outlet conduit and an outlet port;
• ii) a pump piston adapted for reciprocating movement within the cylinder between a first chamber to receive cryogenic fluid through the inlet port during an induction stroke of the piston, and a second chamber to discharge cryogenic fluid through the outlet port during a discharge stroke of the piston;
• iii) means to drive the pump piston between the first and second chambers;
• b) placing the inlet conduit and inlet port of the cryogenic pump in fluid communication with a source of cryogenic fluid to be pumped;
• c) executing reciprocating induction strokes of the piston to provide an inlet feed pressure to induct cryogenic fluid from the source into the first chamber and to remove vapor from the cryogenic fluid in the inlet conduit at a rate faster than the liquid cryogenic fluid in the inlet conduit can vaporize thereby permitting the pump to prime itself at ambient, non-cryogenic temperatures and then to cool the pump to cryogenic temperatures to pump liquid cryogenic fluid from the cryogenic fluid source;
• d) operating the pump piston to generate essentially constant, steady state induction flow conditions;
• and
• e) discharging liquid cryogenic fluid into a cryogenic fluid-receiving container at a positive discharge pressure.

A method of pumping an LNG cryogenic fluid from a source of LNG cryogenic fluid at a cryogenic temperature into a cryogenic fluid-receiving container, which method comprises:

• a) providing a positive displacement, cryogenic pump having:
• i) a pump body with a hollow cylinder, an inlet conduit, an inlet port, an outlet conduit and an outlet port;
• ii) a pump piston adapted for reciprocating movement within the cylinder between a first chamber to receive cryogenic fluid through the inlet port during an induction stroke of the piston, and a second chamber to discharge cryogenic fluid through the outlet port during a discharge stroke of the piston;
• iii) means to drive the pump piston within the cylinder between the first and second chambers;
• b) placing the inlet conduit and inlet port of the cryogenic pump in fluid communication with a source of cryogenic fluid to be pumped through an inlet conduit to the first inlet port;
• c) executing reciprocating induction strokes to provide an inlet feed pressure to induct cryogenic fluid from the source into the first inlet conduit and into the first chamber and to remove vapor from the cryogenic fluid in the inlet conduit at a rate faster than the liquid cryogenic fluid in the inlet conduit can vaporize thereby permitting the pump to prime itself at ambient, non-cryogenic temperatures and then to cool the pump to cryogenic temperatures to pump liquid cryogenic fluid;
• d) operating the pump piston to generate essentially constant, steady state induction flow conditions;
• e) operating the pump piston at a ratio of the volume of the inlet conduit to the induction stroke displacement volume of the pump of about 1:10 to 1:1;
• f) recycling cryogenic fluid vapor developed prior to the pump reaching the cryogenic temperature to the cryogenic fluid source;
• g) operating intermittently the pump between an ambient, non-cryogenic temperature and a cryogenic temperature;
• and
• h) discharging liquid cryogenic fluid into a cryogenic fluid-receiving container at a positive discharge pressure.