Cryogenic pump for liquefied natural gas

Patent metadata

Field	Value
Publication number	US-10024311-B2
Application number	US-201514820326-A
Country	US
Kind code	B2
Filing date	Aug 6, 2015
Priority date	Aug 6, 2015
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

A cryogenic pump for pumping liquefied natural gas (LNG) from a cryogenic tank storing LNG includes a drive assembly and a pump assembly disposed along a pump axis. The drive assembly includes a spool housing having a plurality of spool valves arranged around the pump axis, a tappet housing having a plurality of tappet bores with slidable tappets arranged around the pump axis, and spring housing including a plurality of movably disposed pushrods urged upward by a plurality of associated pushrod springs. Hydraulic fluid received by a hydraulic fluid inlet in the drive assembly is directed by the spool valves to the tappet bores to move the tappets downward against the pushrods. To collect the hydraulic fluid, the lowermost spring housing also includes a collection cavity formed therein that can return the hydraulic fluid to a hydraulic fluid outlet.

First claim

We claim:

1. A cryogenic pump for pumping liquefied natural gas from a cryogenic tank, the cryogenic pump comprising:
a pump assembly adapted to be submersed within a cryogenic tank for storing liquefied natural gas;
a drive assembly configured to hydraulically drive the pump assembly to pump liquefied natural gas from the cryogenic tank; and
a connecting rod housing extending between the drive assembly and the pump assembly and accommodating a plurality of connecting rods, the connecting rod housing defining a pump axis;
wherein the drive assembly further includes:
a spool housing having a plurality of spool valves disposed therein concentrically arranged about the pump axis, the plurality of spool valves each in fluid communication with a high-pressure hydraulic fluid supply;
a tappet housing including a plurality of tappet bores concentrically arranged about the pump axis, each tappet bore in fluid communication with one of the plurality of spool valves and having a tappet slidably disposed therein,
a spring housing including a collection cavity for collecting hydraulic fluid from the tappet bores, the spring housing accommodating a plurality of pushrod springs in the collection cavity;
a plurality of pushrods disposed through the spring housing, each of the plurality of pushrods including a first end projecting into a tappet bore and contacting a tappet and a second end projecting through a pushrod aperture disposed in a spring housing floor of the spring housing to contact at least one of the plurality of connecting rods, each of the plurality of pushrods operatively associated with a pushrod spring to urge the first end into the tappet bore.

2. The cryogenic pump of claim 1 , wherein the drive assembly further includes a plurality of actuators each operatively associated with at least one of the plurality of spool valves.

3. The cryogenic pump of claim 2 , wherein the drive assembly includes a pump flange disposed over the spool housing and having an actuator chamber therein to accommodate the plurality of actuators.

4. The cryogenic pump of claim 3 , wherein the pump flange includes a hydraulic fluid inlet in fluid communication with the high-pressure hydraulic fluid supply, and a hydraulic fluid outlet in fluid communication with a hydraulic fluid reservoir.

5. The cryogenic pump of claim 4 , wherein the pump flange includes a high-pressure circuit communicating hydraulic fluid from the hydraulic fluid inlet to the plurality of spool valves and a low-pressure circuit returning hydraulic fluid from the plurality of spool valves to the hydraulic fluid outlet.

6. The cryogenic pump of claim 5 , wherein each of the plurality of actuators are electrically connected to an electrical controller by one or more molded shielded wires.

7. The cryogenic pump of claim 4 , wherein the tappet housing includes a return path directing hydraulic fluid from the collection cavity to the hydraulic fluid outlet.

8. The cryogenic pump of claim 1 , wherein the spring housing includes a peripheral wall protruding upward from the spring housing floor and surrounding the collection cavity.

9. The cryogenic pump of claim 8 , wherein the collection cavity includes a plurality of cylindrical bores concentrically arranged about the pump axis with each cylindrical bore accommodating at least one of the plurality of pushrods and at least one of the plurality of pushrod springs, the plurality of cylindrical bores being in fluid communication with each other through a plurality of channels.

10. The cryogenic pump of claim 8 , wherein the collection cavity includes a plurality of partial bores, each of the plurality of partial bores forming a semi-circular cutout into the peripheral wall of the spring housing.

11. The cryogenic pump of claim 1 , wherein at least one of the plurality of pushrods includes a pushrod flange protruding radially outward from an elongated rod extension, the pushrod flange abutting at least one of the plurality of pushrod springs.

12. The cryogenic pump of claim 11 , wherein the pushrod flange includes a chamfered face.

13. The cryogenic pump of claim 1 , wherein the pump assembly includes a plurality of reciprocal plungers for pumping the liquefied natural gas.

14. A liquefied natural gas power system comprising
a cryogenic tank for storing liquefied natural gas;
an internal combustion engine operatively associated with the cryogenic tank for receiving liquefied natural gas;
a hydraulic system including a hydraulic pump and a hydraulic reservoir;
a cryogenic pump having a drive assembly and a pump assembly and a pump assembly disposed along a pump axis with a plurality of connecting rods extending generally between the drive assembly and the pump assembly, the drive assembly further including a hydraulic fluid inlet in fluid communication with the hydraulic pump and a hydraulic fluid outlet in fluid communication with the hydraulic fluid reservoir, a spool housing having a plurality of spool valves in fluid communication with the hydraulic fluid inlet, a tappet housing disposed axially underneath the spool housing and having a plurality of tappet bores each operatively associated with one of the plurality of spool valves and each with a tappet slidably disposed therein against one of a plurality of pushrods; and a spring housing accommodating the plurality of pushrods and disposed axially underneath the tappet housing, the spring housing including a collection cavity in fluid communication with the plurality of tappet bores and with the hydraulic fluid outlet.

15. The liquefied natural gas power system of claim 14 , wherein the hydraulic reservoir is elevated above the cryogenic pump.

16. The liquefied natural gas power system of claim 14 , wherein the spring housing accommodates a plurality of pushrod springs each associated with the one of the plurality of pushrods to urge each of the plurality of pushrods axially upward into the tappet housing.

Assignees

• Caterpillar Inc

Inventors

• Brown Cory A
• Brasche Adrienne M
• Baldwin Daniel R
• Ayanji Sudhindra K
• Steffen Joshua W

Classifications

• F04B37/08 Primary

  by condensing or freezing, e.g. cryogenic pumps · CPC title

• F04B23/021

  the pump being immersed in the reservoir · CPC title

• F04B2015/081

  Liquefied gases · CPC title

• F17C2227/0142

  with specified pump type, e.g. piston or impulsive type · CPC title

• F04B23/023

  only the pump-part being immersed, the driving-part being outside the reservoir · CPC title