U.S. patent application number 14/142830 was filed with the patent office on 2014-04-24 for cryogenic pump.
The applicant listed for this patent is Westport Power Inc.. Invention is credited to Alexis Lefevre, Pierre Papirer.
Application Number | 20140109600 14/142830 |
Document ID | / |
Family ID | 44862873 |
Filed Date | 2014-04-24 |
United States Patent
Application |
20140109600 |
Kind Code |
A1 |
Lefevre; Alexis ; et
al. |
April 24, 2014 |
Cryogenic Pump
Abstract
A cryogenic pump is typically used to supply high pressure
natural gas to an engine. The pump has a piston operable to
discharge cryogenic liquid from a pumping chamber within a pump
housing. The cryogenic liquid exits the chamber through an outlet
port in which a check valve is positioned. The check valve has a
valve member which is loaded by a spring and is retained by a
retaining member accessible from outside the housing. The check
valve has an inlet which is axial with the valve member and an
outlet which is transverse to the axis of the valve member.
Inventors: |
Lefevre; Alexis; (Sausheim,
FR) ; Papirer; Pierre; (Reiningue, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Westport Power Inc. |
Vancouver |
|
CA |
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|
Family ID: |
44862873 |
Appl. No.: |
14/142830 |
Filed: |
December 28, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/CA2012/050416 |
Jun 22, 2012 |
|
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14142830 |
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Current U.S.
Class: |
62/50.6 |
Current CPC
Class: |
F04B 53/108 20130101;
F04B 15/08 20130101; F04B 39/1013 20130101; F04B 39/10 20130101;
F04B 53/10 20130101 |
Class at
Publication: |
62/50.6 |
International
Class: |
F04B 15/08 20060101
F04B015/08 |
Claims
1. A cryogenic pump for pumping liquid natural gas comprising: (a)
a piston operable to discharge cryogenic liquid from a pumping
chamber within a pump housing; (b) an outlet port from said pumping
chamber, said outlet port disposed in said pump housing; and (c) a
check valve in said outlet port, said check valve comprising: (i) a
valve member; (ii) a demountable retaining member accessible from
the exterior of said pump housing; (iii) an inlet axial with said
valve member and transverse to the axis of said pumping chamber of
said cryogenic pump; and (iv) an outlet transverse to the axis of
said valve member and parallel to the axis of said pumping chamber
of said cryogenic pump.
2. The cryogenic pump of claim 1, wherein said retaining member
comprises a sleeve for guiding said valve member.
3. The cryogenic pump of claim 2, wherein said sleeve is integral
with said retaining member.
4. The cryogenic pump of claim 1, wherein said valve member is
spring-loaded.
5. The cryogenic pump of claim 4, wherein said valve member
comprises a cylindrical body and a frustoconical head, which, when
said check valve is in its closed position, sealingly engages,
under bias of said spring, a complementary valve seat formed in
said pump housing.
6. The cryogenic pump of claim 5, wherein said head is formed from
plastic material.
7. The cryogenic pump of claim 5, wherein said head is formed from
polytetrafluoroethylene.
8. The cryogenic pump of claim 5, wherein said valve seat is formed
from metal.
9. The cryogenic pump of claim 8, wherein said valve seat is formed
from stainless steel.
10. The cryogenic pump of claim 4, wherein said spring is a
compression spring.
11. The cryogenic pump of claim 10, wherein said compression spring
is seated in a detent formed in said retaining member.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of International
Application No. PCT/CA2012/050416 having an international filing
date of Jun. 22, 2012 entitled "Cryogenic Pump". The '416
international application claimed priority benefits, in turn, from
European Patent Application No. 11352008.4 filed on Jun. 29, 2011.
The '416 international application is hereby incorporated by
reference herein in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a cryogenic pump and
particularly to a check valve for a cryogenic piston pump
BACKGROUND OF THE INVENTION
[0003] A cryogenic pump that utilizes a piston as the pumping
member has a pumping chamber with an outlet port from the pumping
chamber communicating with a conduit for the pumped liquid.
Typically, a check valve is located in the conduit to prevent
backflow of liquid from the conduit to the pumping chamber. A check
valve typically has its inlet and outlet in axial alignment with
one another.
[0004] Cryogenic pumps are typically used in industrial plants for
example, in plant for the separation or liquefaction of industrial
gases. Cryogenic liquefied gases are becoming increasingly widely
used. For example, liquefied natural gas (LNG) is now being used as
an automotive fuel, particularly for heavy goods vehicles (HGVs).
Piston pumps have been developed in order to transfer the LNG from
a storage vessel on board the vehicle to the vehicle's engine. Such
a pump needs to be quite compact and easy to maintain. The pump
typically has a vaporizer associated with it.
[0005] An example of a cryogenic pump suitable for use with LNG on
an HGV is given in U.S. Pat. No. 7,293,418.
SUMMARY OF THE INVENTION
[0006] A cryogenic pump for pumping liquid natural gas comprises:
[0007] (a) a piston operable to discharge cryogenic liquid from a
pumping chamber within a pump housing; [0008] (b) an outlet port
from the pumping chamber, the outlet port disposed in the pump
housing; and [0009] (c) a check valve in the outlet port, the check
valve comprising: [0010] (i) a valve member; [0011] (ii) a
demountable retaining member accessible from the exterior of the
pump housing; [0012] (iii) an inlet axial with the valve member and
transverse to the axis of the pumping chamber of the cryogenic
pump; and [0013] (iv) an outlet transverse to the axis of the valve
member and parallel to the axis of the pumping chamber of the
cryogenic pump.
[0014] In one embodiment, the retaining member comprises a sleeve
for guiding the valve member. The sleeve is preferably formed
integrally with the retaining member.
[0015] In another embodiment, the valve member is spring-loaded.
The valve member preferably comprises a cylindrical body and a
frustoconical head, which, when the check valve is in its closed
position, sealingly engages, under bias of the spring, a
complementary valve seat formed in the pump housing. The head is
preferably formed from plastic material or polytetrafluoroethylene
(PTFE). The valve seat is preferably formed from metal such as
stainless steel).
[0016] In another embodiment, the spring is a compression spring.
The compression spring is preferably seated in a detent formed in
the retaining member.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] A cryogenic pump according to the invention will now be
described, by way of example, with reference to the accompanying
drawings, in which:
[0018] FIG. 1 is a schematic perspective view of the pump;
[0019] FIG. 2 is a sectional side elevation of the warm end of the
pump shown in FIG. 1;
[0020] FIG. 3 is a sectional elevation of the pumping chamber of
the pump shown in FIG. 1; and
[0021] FIG. 4 is an enlarged sectional elevation of part of the
pumping chamber shown in FIG. 3 illustrating the check valve in the
outlet part of the pumping chamber.
[0022] The drawings are not to scale.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)
[0023] Referring to the drawings, there is shown generally a
cryogenic pump 2 of the kind having a cold end 3 adapted to be
immersed in a volume of cryogenic liquid, not shown, to be supplied
to, for example, a combustion engine. Pump 2 is generally of the
same kind as that disclosed in U.S. Pat. No. 7,293,418, save that
it does not include an accumulator. Instead, pump 2 has a pumping
chamber communicating directly with a vaporizer or like heater. The
disclosure of U.S. Pat. No. 7,293,418 is hereby incorporated by
reference herein in its entirety. Cryogenic pump 2 has a warm end 5
opposite cold end 3. Warm end 5 is not intended for immersion in
the cryogenic liquid. Pump 2 has a housing 4 of generally elongate
configuration with an axial piston 6 and piston shaft 7. Piston 6
is able, in operation, to draw cryogenic liquid into, and force
cryogenic liquid out of, a pumping chamber 8 defined within housing
4. Pumping chamber 8 has an inlet 9 for cryogenic liquid
communicating with a hollow cylindrical cryogenic liquid intake
member 11 typically fitted with a filter 11a effective to prevent
small solid particles from entering the pump.
[0024] Pumping chamber 8 has an outlet port 10 for the discharge of
cryogenic liquid. With particular reference to FIGS. 3 and 4,
outlet port 10 houses a check valve 12. Outlet port 10 is connected
to a relatively small diameter conduit 13 which extends from cold
end 3 to warm end 5 of pump 2. Conduit 13 terminates in an annular
heat exchange device 15, in which the cryogenic liquid is vaporized
by indirect heat exchange with a relatively high temperature heat
exchange fluid. (If, for example, the cryogenic liquid is LNG, and
pump 2 is intended to supply the natural gas to an engine (not
shown), the heat exchange fluid can be the aqueous liquid that is
used to cool the engine.) The heat exchange device 15 is provided
with an outlet 99 (see FIG. 2) for vaporized natural gas and an
inlet 19 and outlet 21 for the heat exchange fluid. Typically,
there is within the heat exchange device a passage (not shown) for
the cryogenic liquid in heat exchange relationship with another
passage (not shown) for the heat exchange fluid. Flow of the
cryogenic liquid through its passage causes it to vaporize.
[0025] At warm end 5 of pump 2 there is provided a drive chamber 23
for piston 6. Typically, a hydraulic drive is employed, there being
an inlet port 25 and an outlet port 17 for hydraulic liquid, but an
electrical, pneumatic or mechanical drive could alternatively be
used. The drive arrangements may in general be similar to those
disclosed in U.S. Pat. No. 7,293,418 for the pump described and
shown therein. Piston 6 has two strokes. In its upward stroke (that
is in its stroke away from cold end 3, a flow of cryogenic liquid
through inlet 9 is induced. In its downward stroke (that is in its
stroke away from warm end 5) a flow of cryogenic liquid through
outlet port 10 is provided. Pump 2 is capable of generating a high
delivery pressure, typically in the order of 300 bar, or
higher.
[0026] Check valve 12 is best viewed in FIG. 4. Check valve 12 is
located in pump housing 4 at outlet port 10. Check valve 12 has a
spring-loaded valve member 14 which is retained within housing 4 by
a demountable retaining member 16 accessible from the exterior of
pump housing 4. Retaining member 16 may make a screw-threaded
engagement with pump housing 4 and may have a configuration such
that access can be gained to valve member 14 from outside housing 4
by means of a specific tool (not shown) to dismantle the part, in
association with a standard wrench. In its normal position
retaining member 16 comprises a resilient O-ring seal 40 to prevent
leakage of fluid out of pump 16 via the screw-threads of retaining
member 16. Retaining member 16 has a sleeve 22 for guiding valve
member 14. Sleeve 22 is typically formed integrally with retaining
member 16.
[0027] Valve member 14 has a cylindrical body 24 and a
frustoconical head 26. During the delivery stroke check valve 12
remains open but it closes for the intake stroke of piston 6. If
the pump is idle, check valve 12 remains closed. When check valve
12 is in its closed position, head 26 makes a sealing engagement,
under the bias of a compression spring 28 and any fluid pressure in
outlet 20, with a complementary valve seat 30 formed in pump
housing 4. Typically, head 26 and the rest of valve member 14 are
formed of a plastics material which is able to be used at cryogenic
temperatures. PTFE is one such plastics material.
[0028] Similarly, housing 4 and, in particular, valve seat 30 is
made of a material that in addition to being a metallic engineering
material is suitable for use at cryogenic temperatures. Stainless
steel is one such material. Compression spring 28 is seated in a
detent 32 in retaining member 16. The bias of compression spring 28
acts in a valve-closing direction. Thus, when there is no cryogenic
liquid pressure acting in the opposite direction, valve 12 remains
in a closed position preventing back flow of fluid from conduit 13
into pumping chamber 8. Moreover, the basis of the spring is
effective to keep check valve 12 closed when there is no cryogenic
liquid pressure acting on valve member 14 irrespective of the
attitude of cryogenic pump 2. (In practice, the cryogenic pump is
typically positioned with its axis at angle to the vertical.)
[0029] Valve 12 has an inlet 18 which is axial with valve member 14
and a radial outlet 20 which is transverse to the axis of valve
member 14. Check valve 12, when open, permits cryogenic liquid to
flow from inlet 18 to outlet 20. The flow path has an axial element
being defined between sleeve 22 and a complementary portion of
housing 4 and a transverse radial element through outlet 20, there
being a transverse radial passage 41 through sleeve 22 of retaining
member 16 to aid flow of the cryogenic liquid.
[0030] The position of check valve 12 in housing 4 of cryogenic
pump 2 keeps down the dead volume between piston 6 at the end of
the downward stroke, namely, the stroke away from warm end 5, and
the sealing area of check valve 12, and thereby avoids loss of pump
efficiency.
[0031] Typically, valve member 14 undergoes wear in use, so is
exchanged for an identical such member after a chosen period of
time. In order to exchange valve member 14, pump 2 is withdrawn
from the tank (not shown) containing cryogenic liquid in which it
is typically located, pump 2 allowed to return to ambient
temperature, and retaining member 16 removed.
[0032] While particular elements, embodiments and applications of
the present invention have been shown and described, it will be
understood, that the invention is not limited thereto since
modifications can be made by those skilled in the art without
departing from the scope of the present disclosure, particularly in
light of the foregoing teachings.
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