U.S. patent application number 13/162815 was filed with the patent office on 2011-12-22 for pump cavitation device.
This patent application is currently assigned to S.P.M. Flow Control, Inc.. Invention is credited to Joseph H. Byrne.
Application Number | 20110308967 13/162815 |
Document ID | / |
Family ID | 45327706 |
Filed Date | 2011-12-22 |
United States Patent
Application |
20110308967 |
Kind Code |
A1 |
Byrne; Joseph H. |
December 22, 2011 |
Pump Cavitation Device
Abstract
A sacrificial body mitigates cavitation damage to components
within a pump. The sacrificial body is mounted in the pump so that
flowing fluid passes over the sacrificial body, which causes the
sacrificial body to shed electrons into the flowing fluid in the
vicinity of the cavitation. The excess electrons tend to suppress
hydrogen ions from releasing, which can mitigate cavitation. The
sacrificial body is formed of a material having less resistance to
corrosion due to the flowing fluid than the components of the pump.
Needles are attached to the sacrificial body for immersion in the
flowing fluid to facilitate the release of the electrons for the
sacrificial body.
Inventors: |
Byrne; Joseph H.; (Hudson
Oaks, TX) |
Assignee: |
S.P.M. Flow Control, Inc.
Fort Worth
TX
|
Family ID: |
45327706 |
Appl. No.: |
13/162815 |
Filed: |
June 17, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61355878 |
Jun 17, 2010 |
|
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Current U.S.
Class: |
205/730 ;
204/196.15; 415/9 |
Current CPC
Class: |
F05C 2201/028 20130101;
C23F 13/06 20130101; F04B 53/166 20130101; C23F 13/10 20130101;
F04B 53/16 20130101; F05C 2201/021 20130101; F05C 2201/903
20130101; C23F 13/20 20130101; F05C 2201/02 20130101 |
Class at
Publication: |
205/730 ; 415/9;
204/196.15 |
International
Class: |
C23F 13/02 20060101
C23F013/02; F01D 25/00 20060101 F01D025/00 |
Claims
1. A method of reducing cavitation damage to a component within a
pump, comprising: (a) mounting a sacrificial body within the pump;
and (b) operating the pump to pump fluid at a rate that causes at
least some cavitation to occur on the component, wherein the pumped
fluid flows over the sacrificial body to shed electrons into the
flowing fluid in the vicinity of said cavitation.
2. The method according to claim 1, wherein the sacrificial body
comprises a material that is more easily corroded than the
component.
3. The method according to claim 1, wherein in use the operating
step causes hydrogen ions to release from the component, the
release of which is mitigated by said shedding of electrons from
the sacrificial body.
4. The method according to claim 1, further comprising attaching at
least one needle to the sacrificial body to facilitate the shedding
of the electrons from the sacrificial body.
5. The method according to claim 4, wherein in use the needle is
pointing downstream.
6. The method according to claim 4, wherein the needle is formed of
a metal that is less subject to corrosion than the sacrificial
body.
7. The method according to claim 1, further comprising the step of
mounting an upstream portion of the sacrificial body into the pump,
the sacrificial body having a profile to enhance turbulence of the
fluid flowing over the sacrificial body.
8. The method according to claim 1, wherein the pump is positioned
such that no portion of the pump is immersed in the fluid to be
pumped by the pump.
9. The method according to claim 1, wherein the sacrificial body is
formed from one or more materials from the group comprising zinc,
aluminum, magnesium or alloys thereof.
10. The method according to claim 1, wherein the component
comprises a fluid end block having a chamber, a plunger bore
leading to the chamber, a suction valve port leading to the
chamber, and a discharge valve port passing from the chamber.
11. The method according to claim 10, wherein step (a) comprises
mounting the sacrificial body within the chamber.
12. The method according to claim 10, wherein step (a) comprises
mounting the sacrificial body stationarily within the plunger bore
surrounding the plunger.
13. The method according to claim 10, wherein step (a) comprises
mounting the sacrificial body to the suction valve for movement
therewith.
14. The method according y claim 10, wherein step (a) comprises
mounting the sacrificial body within the suction valve port
upstream from a suction valve.
15. The method according to claim 10, wherein the component
comprises a plunger in the plunger bore.
16. The method according to claim 15, wherein step (a) comprises
mounting a sacrificial body to the plunger.
17. The method according to claim 1, wherein the component
comprises a housing having a rotatable impeller therein.
18. The method according to claim 17, wherein step (a) comprises
mounting the sacrificial body within the housing adjacent a
periphery of the impeller.
19. The method according to claim 17, wherein step (a) comprises
mounting the sacrificial body to the impeller for rotation
therewith.
20. A pump, comprising: a fluid end block having a chamber, a
plunger bore leading to the chamber, a suction valve port leading
to the chamber, and a discharge valve port passing from the
chamber; suction and discharge valves mounted for reciprocation
within the suction valve port and discharge valve port,
respectively; a sacrificial body mounted within the fluid end block
for immersion during use in fluid flow; and the sacrificial body
being formed of a material less resistant to corrosion as compared
to the fluid end block.
21. The pump according to claim 20, further comprising at least one
needle mounted to the sacrificial body, the needle being immersed
in use in the fluid flow.
22. The pump according to claim 21, wherein the needle is formed of
a metal more resistant to corrosion than the sacrificial body.
23. The pump according to claim 20, further comprising a profile
configured to enhance turbulence.
24. The pump according to claim 20, wherein the sacrificial body is
formed from one or more materials from the group comprising zinc,
aluminum, magnesium or alloys thereof.
25. The pump according to claim 20, wherein the sacrificial body
comprises a sleeve mounted stationarily within the plunger bore
surrounding the plunger.
26. The pump according to claim 20, wherein the sacrificial body is
mounted to a forward end of the plunger for movement therewith.
27. The pump according to claim 20, wherein the sacrificial body is
mounted to the suction valve for movement therewith.
28. The pump according to claim 20, wherein the sacrificial body is
mounted within the suction valve port upstream from the suction
valve.
29. A pump, comprising: a housing; a rotatable impeller mounted
within the housing; a sacrificial body mounted within the housing
for immersion within fluid flow as the impeller rotates during use;
and the sacrificial body formed of a material less resistant to
corrosion than the impeller and the housing.
30. The pump according to claim 29, wherein the sacrificial body is
mounted to an interior portion of the housing adjacent a periphery
of the impeller.
31. The pump according to claim 29, wherein the sacrificial body is
mounted to the impeller for rotation therewith.
32. An apparatus for retarding damage to a pump due to cavitation,
comprising: a sacrificial body adapted to be mounted within the
pump, the sacrificial body being formed of a material selected to
shed electrons when immersed within a flowing fluid of the pump;
and at least one needle mounted to the sacrificial body and formed
of a material more resistant to corrosion due to the flowing fluid
than the sacrificial body.
33. The apparatus according to claim 32, wherein the sacrificial
body comprises a sleeve having a profile formed on an exterior
surface to enhance turbulence of fluid flowing over the sleeve in
use, the profile adapted to be upstream of the at least one
needle.
34. The apparatus according to claim 32, wherein the sacrificial
body comprises a disk having a circular periphery and adapted to be
mounted to an inner end of a plunger of the pump, wherein the at
least one needle is mounted to a face of the disk in alignment with
an axis of the disk.
35. The apparatus according to claim 34, wherein the at least one
needle is recessed within a cavity formed in the face of the disk
and a flow port extends through a portion of the disk to a base of
the cavity for directing fluid to the needle.
36. The apparatus according to claim 32, wherein the sacrificial
body comprises a ring adapted to be mounted to a downstream face of
an suction valve of the pump, wherein the at least one needle is
mounted to the face of the ring in alignment with an axis of the
ring.
37. The apparatus according to claim 36, further comprising a flow
port leading from one side of the ring to the face of the ring
adjacent the at least one needle and the flow port being outboard
of an inner diameter of the ring.
38. The apparatus according to claim 32, further comprising a
support rod upon which the sacrificial body is mounted and the
support rod is adapted to be mounted to an interior portion of the
pump.
39. The apparatus according to claim 32, wherein the sacrificial
body is formed from of a material from the group consisting of
zinc, aluminum, magnesium or alloys thereof.
40. The pump according to claim 23, wherein the profile being
located on an upstream portion of the sacrificial body.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to provisional patent
application Ser. No. 61/355,878, filed Jun. 17, 2010.
TECHNICAL FIELD
[0002] This disclosure relates in general to pumps and in
particular to a sacrificial body that mitigates pitting and
corrosion due to cavitation.
BACKGROUND OF THE DISCLOSURE
[0003] Cavitation in pumping devices causes early failure of
components due to erosion/corrosion and the resulting pitting. The
pitting causes several problems: leaks in sealing areas, loss of
pressure integrity, or loss of pressure integrity due to sudden
catastrophic failure from a crack in the pressure chamber that
begins at a cavitation corrosion pit and rapidly propagates through
the pressure containing wall of the pumping chamber. Cavitation
usually initiates in predictable places such as, but not limited
to, near the edge of a sealing surface, areas where there is a
sudden drop in pressure that produces turbulent fluid flow, or at
microscopic discontinuities in the surface of the metal grain and
composition properties.
[0004] Cavitation occurs when there is a rapid drop in pressure in
areas of turbulence, particularly at the beginning of the suction
stroke on a reciprocating pump or on the trailing edge of an
impeller style centrifugal pump. Small air bubbles are formed and
the collapsing of the bubbles can reach boundary velocities high
enough to erode the metal away, causing pitting. During the
formation and collapse of these bubbles chemical changes also
occur, due to the rapid phase change from a liquid to gas, and back
from a gas to liquid which propagates the release of hydrogen ions.
These hydrogen ions have a corrosive effect on the molecular
structure of the metal, causing small particles of the metal to
separate and enter into the fluid stream, contributing to further
acceleration of the pitting process. These hydrogen ions cause the
formation of hydrogen embrittlement cracks, which propogate during
each pumping stroke of a reciprocating pump. Eventually this
cracking begins to penetrate into the pressure containing wall and
rapidly results in a structural failure of the pressure vessel.
[0005] In applications where a lot of fluid is pumped at high
velocities, the maintenance costs due to cavitation
erosion/corrosion can be a significant part of the operating costs.
Eliminating cavitation is unrealistic due to the high pressures and
rapid flow rates needed in many industries. An industry that
experiences high costs of "expendables" is the well service frac
industry. Due to governmental limitations on the weight and the
width of vehicles that are allowed highway access, frac trucks used
in the well service frac industry are made as light and as small as
possible while still being able to achieve the pumping pressures
and flow required. Designed to be as light as possible, the fluid
end and its internal components of the pumps associated with such
well service equipment can wear and fail quickly, due to erosion
and corrosion. When pitting occurs in the pumping chamber of the
fluid end, the stresses concentrate in the pit with the result that
corrosion cracking is initiated and results in the failure of the
fluid end to hold pressure. Replacing of fluid ends is one of the
highest maintenance costs of the well service frac business.
Obtaining a longer lasting fluid end and longer lasting valves,
seats and packing is an important objective of this industry.
Efforts are commonly made to either reduce the cavitation or to
select materials that are more resistant to cavitation erosion and
corrosion. Valves, seats and packing are also destroyed quickly due
to erosion and corrosion, which are accelerated when cavitation
occurs. Slowing the pump speed down can mitigate this problem, but
due to the competitive nature of the business, and the demand for
higher pressure operations, the pumps are run at high speeds, and
cavitation is unavoidable at these speeds.
[0006] Raising the supercharge pressure to the inlet of the pump
may reduces cavitation. Using a properly sized suction pulsation
device can reduce cavitation. But with these solutions implemented
in the industry, and with cavitation erosion/corrosion still
causing expensive maintenance issues, the demand continues for
equipment that will last longer so that operating costs can be
further reduced.
SUMMARY
[0007] In a first aspect, embodiments are disclosed of a method
that reduces cavitation damage to a component within a pump
including mounting a sacrificial body within the pump and operating
the pump to pump fluid at a rate that causes at least some
cavitation to occur on the component, wherein the pumped fluid
flows over the sacrificial body to shed electrons into the flowing
fluid in the vicinity of the cavitation. Since the cavitation
damage of a component having a sacrificial member is reduced as
compared to component not having a sacrificial body, the
sacrificial member advantageously extends the working life of the
component beyond a component not having a sacrificial body mounted
therein.
[0008] In certain embodiments, the sacrificial body includes a
material that is more easily corroded than the component within a
pump.
[0009] In yet other embodiments, during use, the operating step
causes hydrogen ions to release from the component within the pump,
the release of which is mitigated by the shedding of electrons from
the sacrificial body.
[0010] In certain embodiments, the method includes attaching at
least one needle to the sacrificial body to facilitate the shedding
of electrons from the sacrificial body.
[0011] In other embodiments, in use the needle is pointing
downstream.
[0012] In certain embodiments, the needle is formed of a metal that
is less subject to corrosion than the sacrificial body.
[0013] In certain embodiments, the method step of mounting an
upstream portion of the sacrificial body into the pump, provides a
sacrificial body having a profile to enhance turbulence of the
fluid flowing over the sacrificial body.
[0014] In certain embodiments, the pump is positioned such that no
portion of the pump is immersed in the fluid to be pumped by the
pump.
[0015] In certain embodiments, the sacrificial body is formed from
one or more materials from the group comprising zinc, aluminum,
magnesium or alloys thereof.
[0016] In certain embodiments, the turbulence created from mounting
the sacrificial body in the component produces cavitation on a
surface of the sacrificial body rather than allowing the cavitation
bubbles to form on the component. The amount of purposely created
cavitation bubbles and the resulting deterioration of the
sacrificial body is related to the energy needed to overcome the
energy consumed as a gas phase changes to a liquid and a liquid
phase changes back to a gas during cavitation. The energy of the
phase change demands the release of hydrogen ions, which is a
corrosion phenomenon. The sacrificial body is made from materials
that more readily release ions than does the steel of the fluid
chamber; which directs the damaging cavitation corrosion pitting to
the sacrificial body.
[0017] In yet another embodiment, the component includes a fluid
end block having a chamber, a plunger bore leading to the chamber,
a suction valve port leading to the chamber, and a discharge valve
port passing from the chamber.
[0018] In certain embodiments, the method includes mounting the
sacrificial body within the chamber.
[0019] In certain embodiments, the method includes mounting the
sacrificial body stationarily within the plunger bore surrounding
the plunger.
[0020] In certain embodiments, the method includes mounting the
sacrificial body to the suction valve for movement therewith.
[0021] In certain embodiments, the method includes mounting the
sacrificial body within the suction valve port upstream from a
suction valve.
[0022] In another embodiment, the component includes a plunger in
the plunger bore.
[0023] In yet another embodiment, the mounting step includes
mounting a sacrificial body to the plunger.
[0024] In certain of the embodiments, the component includes a
housing having a rotatable impeller therein.
[0025] In certain of the embodiments, the method includes mounting
the sacrificial body within the housing adjacent a periphery of the
impeller.
[0026] In certain of the embodiments, the method includes mounting
the sacrificial body to the impeller for rotation therewith.
[0027] In a second aspect, an embodiment provides a pump having a
fluid end block containing a chamber, a plunger bore leading to the
chamber, a suction valve port leading to the chamber, and a
discharge valve port passing from the chamber. The suction and
discharge valves are mounted for reciprocation within the suction
valve port and discharge valve port, respectively.
[0028] A sacrificial body is mounted within the fluid end block for
immersion during use in the fluid flow as the plunger strokes. The
sacrificial body is formed of a material less resistant to
corrosion as compared to the fluid end block. The embodiment
advantageously provides a pump having a targeted area of cavitation
to mitigate cavitation on the fluid end block, which extends the
working life of the fluid end block. Moreover, the sacrificial
member targeted for cavitation can be replaced over the life of the
fluid end block.
[0029] In certain embodiments, at least one needle is mounted to
the sacrificial body, the needle in use being immersed in the
flowing fluid and pointing in a downstream direction.
[0030] In certain embodiments, the needle is formed of a metal more
resistant to corrosion due to the fluid flowing over the needle
than the sacrificial body.
[0031] In certain of the embodiments, a profile configured to
enhance turbulence is located on an upstream portion of the
sacrificial body.
[0032] In certain embodiments, the sacrificial body is formed from
one or more materials from the group comprising zinc, aluminum,
magnesium or alloys thereof.
[0033] In certain of the embodiments, the sacrificial body includes
a sleeve mounted stationarily within the plunger bore surrounding
the plunger.
[0034] In certain of the embodiments, the sacrificial body is
mounted to a forward end of the plunger for movement therewith.
[0035] In certain of the embodiments, the sacrificial body is
mounted to the suction valve for movement therewith.
[0036] In certain of the embodiments, the sacrificial body is
mounted within the suction valve port upstream from the suction
valve.
[0037] In a third aspect, an embodiment provides a pump including a
housing, a rotatable impeller mounted within the housing, and a
sacrificial body mounted within the housing for immersion in use
within fluid flow as the impeller rotates. The sacrificial body
formed of a material less resistant to corrosion due to the fluid
flow than the impeller and the housing.
[0038] In certain of the embodiments, the sacrificial body is
mounted to an interior portion of the housing adjacent a periphery
of the impeller.
[0039] In certain of the embodiments, the sacrificial body is
mounted to the impeller for rotation therewith.
[0040] In a fourth aspect, an embodiment provides an apparatus for
retarding damage to a pump due to cavitation includes a sacrificial
body adapted to be mounted within the pump, the sacrificial body
being formed of a material selected to shed electrons when immersed
within a flowing fluid of the pump. At least one needle is mounted
to the sacrificial body and formed of a material more resistant to
corrosion due to the flowing fluid than the sacrificial body.
[0041] In certain embodiments, the sacrificial body includes a
sleeve having a profile formed on an exterior surface to enhance
turbulence of fluid flowing over the sleeve, the profile adapted to
be upstream of the at least one needle.
[0042] In certain embodiments, the sacrificial body includes a disk
having a circular periphery and adapted to be mounted to an inner
end of a plunger of the pump. The needle is mounted to a face of
the disk in alignment with an axis of the disk.
[0043] In certain embodiments, the needle is recessed within a
cavity formed in the face of the disk. A flow port extends through
a portion of the disk to a base of the cavity for directing fluid
to the needle.
[0044] In certain embodiments, the sacrificial body includes a ring
adapted to be mounted to a downstream face of an suction valve of
the pump. The needle is mounted to the face of the ring in
alignment with an axis of the ring.
[0045] In certain embodiments, a flow port leads from one side of
the ring to the face of the ring adjacent the needle, the flow port
being outboard of an inner diameter of the ring.
[0046] In certain embodiments, the sacrificial body is mounted on a
support rod. The support rod adapted to be mounted to an interior
portion of the pump.
[0047] In certain of the embodiments, the sacrificial body is
formed from of a material from the group consisting of zinc,
aluminum, magnesium or alloys thereof.
[0048] Other aspects, features, and advantages will become apparent
from the following detailed description when taken in conjunction
with the accompanying drawings, which are a part of this disclosure
and which illustrate, by way of example, the principles
disclosed.
DESCRIPTION OF THE FIGURES
[0049] The accompanying drawings facilitate an understanding of the
various embodiments.
[0050] FIG. 1 is sectional view of a fluid end of a reciprocating
frac pump having a cavitation device in accordance with this
invention.
[0051] FIG. 2 is an enlarged sectional view of a portion of the
cavitation device of FIG. 1.
[0052] FIG. 3 is a sectional view of a fluid end of a reciprocating
pump having a second embodiment of a cavitation device.
[0053] FIG. 4 is an enlarged sectional view of a portion of the
cavitation device of FIG. 3.
[0054] FIG. 5 is a sectional view of a fluid end of a reciprocating
pump having another embodiment of a cavitation device.
[0055] FIG. 6 is an enlarged sectional view of a portion of the
cavitation device of FIG. 5.
[0056] FIG. 7 is a sectional view of a fluid end of a reciprocating
pump having another embodiment of a cavitation device.
[0057] FIG. 8 is an enlarged sectional view of a portion of the
cavitation device of FIG. 7.
[0058] FIG. 9 is a schematic view illustrating a centrifugal pump
having a cavitation device in accordance with this invention.
[0059] FIG. 10 is a schematic view of a centrifugal pump having
another embodiment of a cavitation device in accordance with this
invention.
DETAILED DESCRIPTION
[0060] Referring to FIG. 1, a fluid end 11 illustrates one portion
of a reciprocating pump of a type that is typically used in the
well frac industry. The fluid end 11 is part of a surface mounted
pump, typically mounted on a truck. The fluid end 11 is not
submersed in the fluid to be pumped; rather a flowline leads to the
fluid 11 to convey it to be pumped. The fluid end 11 includes a
fluid end block 13 having a chamber 15. A plunger bore 17
intersects the chamber 15 on one side. A discharge valve port or
passage 19 leads from the chamber 15; a suction on inlet port or
passage 21 leads from the chamber 15 in a generally opposite
direction. In this embodiment, the discharge and suction passages
19 and 21 are coaxial and perpendicular to the plunger bore 17, but
they could be at different angles relative to each other and to the
plunger bore 17.
[0061] A schematically shown discharge valve 20 is located in the
discharge passage 19. The discharge valve 20 is spring-biased to a
closed position, and will open when the pressure in the chamber 15
is sufficiently high. A suction valve 22 is located in the suction
passage 21. The suction valve 22 is biased to a closed position and
will open when the pressure differential of the intake pressure
over the pressure in the chamber 15 is sufficient to overcome the
bias of the spring and allow fluid to be admitted to the chamber
15.
[0062] A flange connector 23 secures to the fluid end block 13 on
one side around the plunger bore 17. A plunger 25 reciprocates
within the flange connector 23 and the plunger bore 17 and is
stroked between an outer intake position and an inner discharge
position by a conventional power source (not shown). A seal or
packing assembly 27 is located in the flange connector 23 and
sealingly engages the outer diameter of the plunger 25. A packing
nut 29 secures to internal threads at the outer end of the flange
connector 23. The packing nut 29, when rotated, preloads the
packing 27 to provide a seal for the plunger 25. Normally, the
fluid end block 13 will have three or five of the chambers 15,
plungers 25, and sets of valves 20 and 22.
[0063] In a first embodiment, a device to retard the effects of
cavitation includes a sacrificial body in the form of a sleeve 31,
which surrounds the plunger 25 and fits stationarily within the
bore of the flange connector 23 and the plunger bore 17. As shown
in FIG. 2, the sleeve 31 has an inner diameter with a turbulence
enhancing profile including one or more grooves 35 or other shapes
that can disrupt laminar flow of fluid. In this example, the groove
35 is helical. The inner diameter of the sleeve 31 optionally may
be in sliding contact with the outer diameter of the plunger 25. In
this example, the sleeve 31 has an external flange 33 on its outer
end that mates with a shoulder within the flange connector 23. The
inner end or rim 40 of the sleeve 31 may be substantially flush
with the inside wall of the chamber 15. Consequently, when the
plunger 25 is in the full power stroke position, which will be to
the right of the position shown in FIG. 1, the inner end of the
plunger 25 will be protruding farther into the chamber 15 than the
rim 40 of the sleeve 31.
[0064] Referring still to FIG. 2, bypass ports 37 extend through
the sidewall of the sleeve 31. The inner end of each of the bypass
ports 37 intersects one turn of the helical groove 35. The bypass
ports 37 are spaced circumferentially around the sleeve 31 and
along a portion of the length of the sleeve 31. In this embodiment,
the outer diameter of the sleeve 31 is smaller than the inner
diameter of the plunger bore 17, creating an annulus surrounding
the sleeve 31. This arrangement causes some of the fluid being
pushed by the plunger 25 during the inward or power stroke to flow
through the bypass ports 37 and into the annulus between the outer
diameter of the sleeve 31 and the plunger bore 17. A turbulence
creating profile 38 on the outer diameter of the sleeve 31 may also
include a helical groove or other shapes. The helical groove 35 and
the ports 37 enhance turbulence and cause cavitation to occur in
the annulus during the power stroke.
[0065] The sacrificial body includes a number of needles 39 (only
one shown) mounted around rim 40 of the sleeve 31. The turbulent
fluid flowing out the annulus during the power stroke flows around
them. Each of the needles 39 has a sharp tip and protrudes inward
or downstream from the rim 40 into the chamber 15 (FIG. 1). Each of
the needles 39 may be parallel to the axis of the plunger bore
17.
[0066] The sleeve 31 is a sacrificial body formed of a material or
materials that has characteristics for easily releasing electrons.
The material may be, for example, zinc, aluminum, magnesium or
alloys of these metals. This material is of a less noble metal than
the fluid end block 13, which is formed of a steel alloy. The
material of the sleeve 31 has a lower electrochemical potential
than the steel alloy of the fluid end block 13, thus the sleeve 31
will corrode more easily due to fluid flowing over it.
[0067] The needles 39 can be made of a metal more resistant than
the metal of the sleeve 31 to mitigate corrosion and pitting of the
needles. Thus the needles 39 will be of a material with a higher
electrochemical potential than the sleeve 31. For example, the
needles 39 may be fanned of stainless steel. The metal of the base
of each of the needles 39 will be in contact with the metal of the
sleeve 31 such that the needles 39 and the sleeve 31 serve to shed
or emit electrons from the sleeve 31 into the fluid flowing past
the needles 39.
[0068] As mentioned, the sleeve 31 may have profiles to enhance
cavitation, causing the formation and collapse of bubbles which, if
unchecked, can result in chemical changes of the steel components,
particularly the release of hydrogen ions. Hydrogen ions have a
corrosive effect on the molecular structure of the metal of the
fluid end block 13, causing small particles of the metal to
separate and enter the fluid stream. This release of metal
particles contributes to pitting. The release of negatively-charged
electrons from the needles 39 mitigates the formation of hydrogen
ions, which are also negatively charged. Because of the cavitation,
erosion and corrosion will occur on the sleeve 31; however, it is
intended to be expendable. The sleeve 31 is not connected to any
voltage potential, rather releases electrons as a result of the
turbulent fluid flowing over it.
[0069] Referring to FIGS. 3 and 4, in this second embodiment, the
fluid end 41 has conventional discharge and suction valves 43, 45
as in the first embodiment. The fluid end 41 has a chamber 47, and
a plunger 49 extends inward through a flange connector 51. In this
embodiment, a disk 53 mounts to the inner end 57 of the plunger 49
to serve as a sacrificial body. Referring to FIG. 4, a coaxial
cylindrical recess 55 is formed in a plunger inner end 57. The disk
53 is secured within the recess 55, such as by a retainer ring 59.
Small, cylindrical cavities 61 are formed within the face of the
disk 53. Each of the cavities 61 has an open inner end exposed to
chamber 47 (FIG. 4), and a closed base. A needle 63 is secured in
metal-to-metal contact in the base of each of the cavities 61. In
this example, the needles 63 do not protrude past the face of the
disk 53, rather are fully recessed. A bypass port 65 extends from
an outer diameter of the plunger 49 into one of the cavities 61.
The intersection of the bypass port 65 with the cavity 61 is near
the base of the cavity 61. Although only a single one of the bypass
ports 65 is shown, preferably other of the bypass ports 65 will
connect the other cavities 61 to the outer diameter of the plunger
49.
[0070] As the plunger 49 strokes inward, the fluid will flow into
each of the cavities 61, around one of the needles 63, then out one
of the bypass ports 65 to the outer diameter of the plunger 49. The
swirling fluid causes cavitation to occur as it flows around the
needles 63. The components of the needles 63 and the disk 53 may be
the same materials as in the first embodiment to facilitate the
shedding of electrons for the same purpose as discussed above.
[0071] Referring to FIG. 5, a fluid end 67 is constructed generally
as in the first two embodiments. The fluid end 67 has a chamber 69
and discharge and suction valves 71, 73. A plunger 75 extends into
the chamber 69 from one side. Discussing the suction valve 73 in
more detail, the body of the suction valve 73 has a seal 77 that
may be of conventional design. The suction valve 73 is biased by a
spring 79 to force the seal 77 into sealing engagement with a seat
81. The seat 81 is a cylindrical member having a sealing surface on
its inner edge or rim. Referring to FIG. 6, the body of the valve
73 has an outer diameter 83 and an inner or upper end 85. An
annular recess 87 is formed at a junction of the inner end 85 and
the outer diameter 83. A sacrificial body comprising a ring 89 is
mounted in the recess 87. The outer diameter of the ring 89 is
flush with the outer diameter 83, and the inner end of the ring 89
is flush with the valve body inner end 85.
[0072] The ring 89 has a plurality of needles 91 (only one shown)
mounted to its face. The needles 91 extend inward, parallel with an
axis of the seat ring 81. The needles 91 protrude inward past the
inner end 85 of the suction valve 73. The ring 89 and the needles
91 may be formed of the same materials as the first embodiment for
emitting electrons. To facilitate the cavitation occurring in the
vicinity of the needles 91, a number of bypass ports 93 (only one
shown) extend obliquely from the inner side of the ring 89. Each of
the bypass ports 93 also extends to the valve body outer diameter
83. As the valve 73 strokes toward and away from the seat 81, fluid
will be forced through the bypass ports 93 and around the needles
91. Preferably one of the bypass ports 93 will be located adjacent
each of the needles 91.
[0073] Another embodiment is illustrated in FIGS. 7 and 8. A fluid
end 95 has the same general construction as in the other
embodiments. The fluid end 95 has a chamber 97, discharge and
suction valves 99, 101 and a plunger 103. In this example, a
sacrificial body 105 is located near the base or lower end of the
suction valve 101. The sacrificial body 105 is a block of electron
emitting material mounted to a curved support rod 107, which may be
bent into a desired position. The support rod 107 has an axially
extending portion that positions the sacrificial body 105 within
the seat ring 109. In this example, the support rod 107 is bent
into a right angle and has a mounting plug 111 on its outer end.
The plug 111 secures to a flange port 113 that extends through a
intake fluid end 114. The plug 111 seals the flange port 113 to
prevent fluid from passing through the port 113. The sacrificial
body 105 is spaced from contact with any portion of the suction
valve 101.
[0074] As shown in FIG. 8, the sacrificial body 105 has one or more
needles 115 that face upward. The needles 115 are subjected to
fluid flow by bypass ports 117 extending through the sacrificial
body 105. In this embodiment, at least two of the needles 115 are
mounted to the sacrificial body 105. A portion of the fluid flowing
upward toward the suction valve 101 will be diverted through the
bypass passages 117 to flow around the needles 115. The sacrificial
body 105 is formed of a metal that is good at shedding electrons,
as previously discussed. Electrons will inhibit hydrogen ions being
formed that could otherwise result in pitting of the body of the
seat 109 and the valve 101.
[0075] At least some of the embodiments for the reciprocating pumps
illustrated in FIGS. 1-8 may be combined with others. For example,
the embodiments dealing with pitting of the valves, shown in FIGS.
5-8, could be employed in connection with one of the devices shown
in FIGS. 1-4. Similarly, an arrangement to avoid pitting of the
valves may be employed with the discharge valve in the same manner
as employed with the suction valve.
[0076] Referring to FIG. 9, a different type of pump 119 is
illustrated. Pump 119 is a centrifugal pump having a housing 121
with an outlet 123. The inlet is not shown. One or more impellers
125 is mounted in the housing 121 and rotates relative to the
housing 121. Each of the impellers 125 has a hub 127 about which
the impeller 125 is rotated via a shaft (not shown). Each of the
impellers 125 has a plurality of vanes 129 that spiral outward from
the hub 127. The spaces between the vanes 129 include passages for
fluid that enters near the hub 127. The fluid flows outward and
discharges through the outlet 123.
[0077] In this embodiment, a number of sacrificial bodies 131 are
mounted stationarily around the inner wall of the housing 121. The
sacrificial bodies 131 include needles 135 that point generally in
a downstream direction so that fluid flowing past will collect
electrons to suppress hydrogen ions that might otherwise occur in
the vicinity of the inner wall of the housing 121. In this example,
the sacrificial body 131 has a mounting portion shown on the
exterior of the housing 121. The mounting portion could be located
within the interior. Also, the inner wall of the housing 121 could
include a portion of a diffuser for each of the impellers 125. As
in the other embodiments, the sacrificial bodies 131 are formed of
a sacrificial metal for shedding electrons into the fluid flow.
[0078] In the embodiment of FIG. 10, a centrifugal pump 137 is also
schematically shown to include a housing 139 and an impeller 140.
In this embodiment, sacrificial bodies 141 are mounted to several
vanes 145 for rotation therewith. Each of the sacrificial bodies
141 includes a needle 143 that points in a direction opposite to
the direction of rotation of the impeller 140, as shown by the
arrow. The sacrificial bodies 141 are formed of a material for
shedding electrons as previously discussed in connection with the
other embodiments.
[0079] The various embodiments in FIGS. 1-10 disclose sacrificial
bodies that corrode as a result of fluid flowing over them. The
corrosion of the sacrificial bodies releases electrons into the
fluid flow that inhibit corrosion of more expensive components of
the pumps, such as fluid end blocks and housings. The sacrificial
bodies are readily replaced and inexpensive.
[0080] In the foregoing description of certain embodiments,
specific terminology has been resorted to for the sake of clarity.
However, the disclosure is not intended to be limited to the
specific terms so selected, and it is to be understood that each
specific term includes other technical equivalents which operate in
a similar manner to accomplish a similar technical purpose. Terms
such as "left" and right", "front" and "rear", "above" and "below"
and the like are used as words of convenience to provide reference
points and are not to be construed as limiting terms.
[0081] In this specification, the word "comprising" is to be
understood in its "open" sense, that is, in the sense of
"including", and thus not limited to its "closed" sense, that is
the sense of "consisting only of". A corresponding meaning is to be
attributed to the corresponding words "comprise", "comprised" and
"comprises" where they appear.
[0082] In addition, the foregoing describes only some embodiments
of the disclosure, and alterations, modifications, additions and/or
changes can be made thereto without departing from the scope and
spirit of the disclosed embodiments, the embodiments being
illustrative and not restrictive.
[0083] Furthermore, the disclosure has been described in connection
with what are presently considered to be the most practical and
preferred embodiments. It is to be understood that the disclosure
is not to be limited to the disclosed embodiments, but on the
contrary, is intended to cover various modifications and equivalent
arrangements included within the spirit and scope of the
disclosure. Also, the various embodiments described above may be
implemented in conjunction with other embodiments, e.g., aspects of
one embodiment may be combined with aspects of another embodiment
to realize yet other embodiments. Further, each independent feature
or component of any given assembly may constitute an additional
embodiment.
* * * * *