U.S. patent application number 13/667736 was filed with the patent office on 2014-05-08 for variable capacity plunger pump.
This patent application is currently assigned to CATERPILLAR INC.. The applicant listed for this patent is CATERPILLAR INC.. Invention is credited to Chris Paul Buckley, Matthew Paul Giacomi, Ryan A. Johnson, Ronald Dean Shinogle.
Application Number | 20140127062 13/667736 |
Document ID | / |
Family ID | 50622538 |
Filed Date | 2014-05-08 |
United States Patent
Application |
20140127062 |
Kind Code |
A1 |
Buckley; Chris Paul ; et
al. |
May 8, 2014 |
VARIABLE CAPACITY PLUNGER PUMP
Abstract
A plunger pump includes a housing with a discharge valve in
communication with an outlet. The housing includes a bore that
slidably accommodates a plunger. The housing also includes an
inlet. The plunger has a closed proximal end connected to an
actuator and a distal end with an outlet valve. The plunger also
includes a sidewall with an opening that is in communication with
the inlet of the housing. Fluid flows through the inlet and through
the opening and into the plunger. When the plunger is retracted
away from the discharge valve, the outlet valve of the plunger
opens thereby providing fluid for the housing bore. As the plunger
is moved towards the discharge valve, pressure in the housing bore
increases thereby opening the discharge valve and permitting the
pressurized fluid to exit through the outlet.
Inventors: |
Buckley; Chris Paul;
(Naperville, IL) ; Shinogle; Ronald Dean; (Peoria,
IL) ; Johnson; Ryan A.; (Ransom, IL) ;
Giacomi; Matthew Paul; (Joliet, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CATERPILLAR INC. |
Peoria |
IL |
US |
|
|
Assignee: |
CATERPILLAR INC.
Peoria
IL
|
Family ID: |
50622538 |
Appl. No.: |
13/667736 |
Filed: |
November 2, 2012 |
Current U.S.
Class: |
417/439 |
Current CPC
Class: |
F04B 53/10 20130101;
F04B 53/168 20130101; F04B 53/16 20130101; F04B 53/166
20130101 |
Class at
Publication: |
417/439 |
International
Class: |
F04B 19/22 20060101
F04B019/22 |
Claims
1. A pump comprising: an inlet to receive fluid; an outlet to
discharge fluid; a housing assembly defining a housing bore; an
axial plunger slidably disposed within the housing bore to form a
compression chamber disposed between a distal end of the plunger
and the outlet, the compression chamber in axial alignment with the
outlet, the plunger configured to receive fluid from the inlet and
pass fluid to the compression chamber; wherein when the plunger is
at a first position the compression chamber is at a first volume to
receive fluid from the plunger at a first pressure, and when the
plunger is at a second position, the compression chamber is at a
smaller second volume to pressurize the fluid within the
compression chamber to a higher second pressure, wherein the fluid
at the second pressure is discharged from the compression chamber
into the outlet.
2. The pump of claim 1 further comprising a liner disposed along at
least a portion of the housing bore.
3. The pump of claim 2, wherein the liner is removable.
4. The pump of claim 3 wherein the inlet is disposed between the
proximate and middle seals.
5. The pump of claim 1 wherein the inlet has an inlet axis and the
housing bore has a bore axis that is at least substantially
perpendicular to the inlet axis.
6. The pump of claim 1 wherein the proximal end of the plunger is
coupled to an actuator.
7. The pump of claim 1 wherein the housing assembly may be coupled
to a plurality of pumps as described in claim 1.
8. The pump of claim 1 wherein the outlet valve assembly and the
discharge valve assembly are biased towards closed positions when
the plunger is stationary in the loaded position.
9. The pump of claim 1 wherein the outlet valve assembly is biased
towards a closed position and the discharge valve assembly is
biased towards an open position when the plunger is moved from the
loaded position to the dispense position.
10. The pump of claim 1 wherein the outlet valve assembly is biased
towards an open position and the discharge valve assembly is biased
towards a closed position when the plunger is moved from the
dispense position towards the loaded position.
11. A pump comprising: an inlet to receive fluid; an outlet to
discharge fluid; a housing assembly defining a housing bore; an
axial plunger slidably disposed within the housing bore to form a
compression chamber disposed between a distal end of the plunger
and the outlet, the compression chamber in axial alignment with the
outlet, the plunger having a sidewall defining a plunger bore
extending therethrough, the plunger including at least one opening
formed in the sidewall configured to pass fluid from the inlet into
the plunger bore, the plunger configured to communicate fluid from
the plunger bore and to the compression chamber; wherein when the
plunger is at a first position the compression chamber is at a
first volume to receive fluid from the plunger at a first pressure,
and when the plunger is at a second position, the compression
chamber is at a smaller second volume to pressurize the fluid
within the compression chamber to a higher second pressure, wherein
the fluid at the second pressure is discharged from the compression
chamber into the outlet.
12. The pump of claim 11 wherein the inlet has an inlet axis and
the housing bore has a bore axis that is at least substantially
perpendicular to the inlet axis.
13. The pump of claim 11 wherein the proximal end of the plunger is
coupled to an actuator.
14. The pump of claim 11 wherein a portion of the housing bore
accommodates a removable liner having a thickness that reduces the
volume of the housing bore.
15. The pump of claim 11 wherein the housing assembly may be
coupled to a plurality of pumps as described in claim 11.
16. The pump of claim 11 wherein the outlet valve assembly and the
discharge valve assembly are biased towards closed positions when
the plunger is stationary in the loaded position.
17. The pump of claim 11 wherein the outlet valve assembly is
biased towards a closed position and the discharge valve assembly
is biased towards an open position when the plunger is moved from
the loaded position to the dispense position.
18. The pump of claim 11 wherein the outlet valve assembly is
biased towards an open position and the discharge valve assembly is
biased towards a closed position when the plunger is moved from the
dispense position towards the loaded position.
19. A method for pumping hydraulic fracturing fluid, the method
comprising: retracting a plunger to increase a volume of a
compression chamber defined within a housing bore of a pump between
a distal end of the plunger and an outlet of the pump, and to
provide communication between an inlet of the pump and the
compression chamber in order to receive fluid in a plunger bore of
the plunger, the compression chamber in axial alignment with the
outlet, the plunger configured to communicate fluid from the
plunger bore and to the compression chamber; moving the plunger to
reduce a volume of the compression chamber to pressurize the fluid
within the compression chamber; and dispensing the pressurized
fluid from the compression chamber to the outlet.
20. The method of claim 19 further including: altering an output
capacity of the pump by lining the housing bore with a replaceable
liner.
21. A pumping module comprising: a plurality of pumps arranged in a
side by side configuration, each pump including: an inlet to
receive fluid; an outlet to discharge fluid; a housing assembly
defining a housing bore; an axial plunger slidably disposed within
the housing bore to form a compression chamber disposed between a
distal end of the plunger and the outlet, the compression chamber
in axial alignment with the outlet, the plunger configured to
receive fluid from the inlet and pass fluid to the compression
chamber; wherein when the plunger is at a first position the
compression chamber is at a first volume to receive fluid from the
plunger at a first pressure, and when the plunger is at a second
position, the compression chamber is at a smaller second volume to
pressurize the fluid within the compression chamber to a higher
second pressure, wherein the fluid at the second pressure is
discharged from the compression chamber to the outlet.
Description
TECHNICAL FIELD
[0001] This disclosure relates to hydraulic fracturing in general
and, more specifically, to plunger pumps used for pumping
pressurized fracturing fluid down wellbores for purposes of
reservoir stimulation.
BACKGROUND
[0002] Subterranean hydraulic fracturing is conducted to increase
or stimulate production from a hydrocarbon well. To conduct a
fracturing process, high pressures are used to pump special
fracturing fluids, including some that contain "proppants", down
the well-bore and into a hydrocarbon formation to split or
"fracture" the rock formation along veins or planes extending from
the well-bore. Once the desired fracture is formed, the fluid flow
is reversed and the liquid portion of the fracturing fluid is
removed. The proppants are intentionally left behind to stop the
fracture from closing onto itself due to the weight and stresses
within the formation.
[0003] The proppants support the fractures in open positions, yet
remain highly permeable to hydrocarbon fluid flow since they form a
packed bed of particles with interstitial void spaces that provide
permeability. Sand is one example of a commonly-used proppant.
Fractures that are propped open with proppant clusters can thus
serve as new formation drainage areas and new flow conduits from
the formation to the well-bore, thereby providing increased flow
rates, and hence increased hydrocarbon production.
[0004] Plunger pumps are commonly used in the oil and gas industry
for hydraulic fracturing purposes. Plunger pumps have a fluid end
and a power end that drives the fluid end. Plunger pumps that are
used to pump fracturing fluids down a well-bore generally require
power ends rated at 2,000 hp (1492 W) or more. To reach this power
level, multiplex plunger pumps (i.e., more than one plunger) may be
used as disclosed in US 2012/0063936.
[0005] The fluid ends of plunger pumps frequently have a service
life of less than 200 hours as the fracturing fluid proppant
slurries are abrasive. Further, other well stimulation fluids may
be corrosive. Still further, well stimulation fluids including
fracturing fluids are pumped at rates of up to 100 bbl/min (16
kl/min) and pressures of 10,000 psi (5.2.times.10.sup.5 mmHg) or
more.
[0006] The fluid ends (or outlets) of plunger pumps have many parts
that are releasably fastened to one another so that the plungers
and valves can be easily repaired or replaced as disclosed in US
2012/0222760. However, the connections between the parts and the
supporting features for the valves and the 90.degree. turns that
tend to weaken a fluid end, limiting its pressure rating, and
making it susceptible to cracking under high, cyclical stresses.
Thus, while many improvements for extending the service life and/or
facilitating the maintenance of plunger pumps have been developed,
short service lives and/or complex maintenance requirements
persist.
SUMMARY
[0007] In one aspect, a pump is disclosed. The pump may include an
inlet for receiving fluid and an outlet for discharging fluid. The
pump may also include a housing assembly that defines a housing
bore. The pump may also include an axial plunger slidably disposed
within the housing bore to form a compression chamber disposed
between a distal end of the plunger and the outlet. The compression
chamber may be in axial alignment with the outlet. The plunger may
be configured to receive fluid from the inlet and pass fluid to the
compression chamber. When the plunger is at a first position, the
compression chamber may be at a first volume for receiving fluid
from the plunger at a first pressure. Further, when the plunger is
at a second position, the compression chamber may be at a smaller
second volume to pressurize the fluid within the compression
chamber to a higher second pressure. The fluid at the second
pressure may then be discharged from the compression chamber into
the outlet.
[0008] In another aspect, a pump with an inlet for receiving fluid
and an outlet for discharging fluid is also disclosed. The pump may
also include a housing assembly that defines a housing bore. The
pump may also include an axial plunger slidably disposed within the
housing bore to form a compression chamber disposed between a
distal end of the plunger and the outlet. The compression chamber
may be in axial alignment with the outlet. The plunger may have a
side wall that defines a plunger bore. The plunger may include at
least one opening formed in the side wall of the plunger that is
configured to pass fluid from the inlet into the plunger bore. The
plunger may then be configured to communicate fluid from the
plunger bore to the compression chamber. When the plunger is at a
first position, the compression chamber may be at a first volume to
receive fluid from the plunger at a first pressure. When the
plunger is at a second position, the compression chamber may be at
a smaller second volume to pressurize fluid within the compression
chamber to a higher second pressure. Fluid at the second pressure
may then be discharged from the compression chamber into the
outlet.
[0009] A method for pumping hydraulic fracturing fluid is also
disclosed. The method may include retracting a plunger to increase
a volume of a compression chamber defined within a housing bore of
a pump between a distal end of the plunger and an outlet of the
pump. The plunger may also provide communication between an inlet
of the pump and the compression chamber in order to receive fluid
in a plunger bore of the plunger. The compression chamber may be in
axial alignment with the outlet of the pump. The plunger may be
configured to communicate fluid from the plunger bore to the
compression chamber. The method may further include moving the
plunger to reduce a volume of the compression chamber to pressurize
fluid within the compression chamber and the method may further
include dispensing the pressurized fluid from the compression
chamber to the outlet.
[0010] In another aspect, a pump module is disclosed. The pumping
module may include a plurality of pumps arranged in a side by side
configuration. Each pump may include an inlet for receiving fluid,
an outlet for discharging fluid and a housing assembly defining a
housing bore. Each pump may further include an axial plunger
slidably disposed within the housing bore to form a compression
chamber disposed between a distal end of the plunger and the
outlet. The compression chamber may be in axial alignment with the
outlet. The plunger may be configured to receive fluid from the
inlet and pass fluid to the compression chamber. When the plunger
is at a first position, the compression chamber may be at a first
volume to receive fluid from the plunger at a first pressure. When
the plunger is at a second position, the compression chamber may be
at a smaller second volume to pressurize the fluid within the
compression chamber to a higher second pressure, which results in
the fluid at the second higher pressure being discharged from the
compression chamber to the outlet.
[0011] A discharge valve assembly for a pump is also disclosed. The
discharge valve assembly may include a discharge valve sleeve
coupled to a bore of a pump. The discharge valve sleeve may include
a radial inwardly directed valve seat at a proximal end of the
discharge valve sleeve. The discharge valve assembly may also
include a retainer that may include a proximal side spaced apart
from the valve seat and a distal side that faces an outlet of the
pump. The retainer may have a hub that extends proximally from the
proximal side of the retainer and the retainer may also include at
least one passageway axially extending through the retainer to
provide communication between the proximal side of the retainer and
the outlet of the pump. The discharge valve assembly may also
include a discharge valve head disposed between the retainer and
the discharge valve seat. The discharge valve head may have a
proximal side to sealably engage the valve seat when the discharge
valve assembly is in a closed position. The discharge valve head
may also include a shaft that extends from a distal side of the
discharge valve head that is slidably received in the hub of the
retainer.
[0012] In yet another aspect, a pump is disclosed that includes an
inlet for receiving fluid and an outlet for discharging fluid. The
pump may also include a housing assembly that defines a housing
bore. The pump may further include an axial plunger slidably
disposed within the housing bore to form a compression chamber
disposed between a distal end of the plunger and the outlet. The
compression chamber may be in axial alignment with the outlet. The
plunger may be configured to receive fluid from the inlet and pass
fluid through the compression chamber. A discharge valve sleeve may
be included that is coupled to the housing bore. The discharge
valve sleeve may include a valve seat at a proximal end of the
discharge valve sleeve. The pump may also include a retainer that
includes a proximal side spaced apart from the valve seat and a
distal side that faces the outlet of the pump. The retainer may
have a hub extending proximally from the proximal side of the
retainer. The retainer may include at least one passageway
extending through the retainer to provide communication between the
proximal side of the retainer and the outlet. The pump may also
include a discharge valve head disposed between the retainer and
the discharge valve seat. The discharge valve head may have a
proximal side that sealably engages the valve seat when the
discharge valve assembly is in a closed position and a shaft
extending from a distal side of the discharge valve head that is
slidably received within the hub of the retainer. The discharge
valve head may be biased towards a closed position where the
discharge valve head engages the discharge valve seat. When the
pressure of the fluid in the compression chamber is beyond a
threshold pressure, the discharge valve head may be movable away
from the closed position to permit pressurized fluid to move from
the compression chamber to the outlet.
[0013] A method for pumping hydraulic fracturing fluid is also
disclosed. The method may include biasing a discharge valve head
against a discharge valve seat to close an outlet of a pump. The
discharge valve head may be connected to a shaft that may be
slidably received within a hub that may be connected to a proximal
side of a retainer. The method may include providing communication
between an inlet of the pump and an axial housing bore defined by a
housing assembly of the pump. The method may further include moving
a plunger disposed axially within the housing bore towards the
discharge valve head thereby pressurizing a portion of the housing
bore disposed between the plunger and the discharge valve head to
form a compression chamber in axial alignment with the discharge
valve head thereby overcoming the bias of the discharge valve head
against the valve seat and providing communication between the
compression chamber and the outlet of the pump. The method may
further include dispensing fluid through the outlet.
[0014] A plunger for a plunger pump is also disclosed. The plunger
may include as sidewall extending between a proximal end and an
open distal end. The sidewall may have a plunger bore extending
axially through the sidewall. The sidewall may also include at
least one opening to receive fluid from an inlet of the plunger
pump into the plunger bore. The plunger may also include a valve
seat that is coupled to the distal end of the plunger. The plunger
may also include an outlet valve head for sealable engagement with
the valve seat. The plunger may further include a rod that extends
axially from the outlet valve head within the plunger bore. The rod
may also include a proximal end coupled to a piston that may be
slidably received within the plunger bore. The rod may also include
a distal end coupled to the outlet valve head. The outlet valve
head, the rod and the piston may form a valve assembly movable
between open and closed positions. In the closed position, the
piston is at a first position and the outlet valve head is
configured to sealably engage the valve seat. In the open position,
the position is moved distally away from the first position and the
outlet valve head is moved away from the valve seat.
[0015] A plunger pump is also disclosed. The plunger pump may
include a housing assembly including an inlet, an outlet and an
axial housing bore extending therebetween. The housing bore may
slidably accommodate a plunger. The plunger may include a sidewall
that extends between a proximal end and a distal end of the plunger
and the sidewall may define a plunger bore extending axially within
the sidewall. The plunger may be configured to receive fluid from
an inlet of the plunger pump into the plunger bore. The plunger may
also include a valve seat and an outlet head for sealable
engagement with the valve seat. The plunger may further include a
rod that extends axially from the outlet head within the plunger
bore and a piston may be coupled to a proximal end of the rod. A
distal end of the rod may be coupled to the outlet valve head. The
piston may be slidably received within the plunger bore. The outlet
head, rod and piston form a valve assembly that is movable between
open and closed positions. In the closed position, the piston may
be at a first position and the outlet head may be configured to
sealably engage the valve seat. In the open position, the piston
may be moved distally away from the first position and the outlet
valve head may be moved away from the valve seat.
[0016] In another aspect, a method for pumping hydraulic fracturing
fluid is also disclosed. The method may include providing a pump
with an inlet, an outlet, a proximal end, a distal end and an axial
housing bore which slidably receives a plunger. The method may
further include retracting the plunger axially away from a
discharge valve assembly connected to the outlet of the pump that
may be disposed at a distal end of the pump. The retracting of the
plunger may reduce pressure in the axial housing bore of the pump
which may open an outlet valve assembly disposed at a distal end of
the plunger. The method may further include providing communication
between an inlet of the pump and the housing bore of the pump
through the open outlet valve assembly of the plunger. The method
may further include moving the plunger towards the discharge valve
assembly thereby increasing pressure in the housing bore thereby
closing the outlet valve assembly. The method may further include
pressurizing at least a portion of the housing bore disposed
between the outlet valve assembly of the plunger and the discharge
valve assembly thereby opening the discharge valve assembly.
Finally, the method may further include dispensing fluid through
the open discharge valve assembly to the outlet.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a sectional view of a disclosed plunger pump in a
loaded or ready-to-dispense position.
[0018] FIG. 2 is another sectional view of the plunger pump shown
in FIG. 1 in a dispense position with the discharge valve assembly,
shown at the right, being open.
[0019] FIG. 3 is an enlarged view of the replaceable discharge
valve assembly as shown in FIG. 2.
[0020] FIG. 4 is a sectional view of the pump shown in FIGS. 1-3 in
a reload position illustrating a retraction of the plunger to the
left thereby opening the outlet valve assembly disposed at the end
of the plunger which permits a reloading of the housing bore
defined with fluid from the inlet.
[0021] FIG. 5 is an enlarged view of the open outlet valve assembly
disposed at the end of the plunger.
[0022] FIG. 6 is a perspective view of three disclosed pumps
connected in parallel.
[0023] FIG. 7 is a perspective view of five disclosed pumps
connected in parallel.
[0024] FIG. 8 graphically illustrates the relationship between
fluid pressure in the housing bore and the position of the
plunger.
DESCRIPTION
[0025] FIG. 1 illustrates a cross-section of a disclosed plunger
pump 10 in a static position where the discharge valve assembly 11
shown at the right in FIG. 1 near the outlet 12 and the outlet
valve assembly 13 disposed at the end of the plunger 14 are both in
a closed position. The pump 10 may include a housing assembly 15
that may be unitary in construction or that may be provided in
multiple parts as shown in FIG. 1. Specifically, the housing
assembly 15 includes an inlet housing 16 having a proximal end 17
that may be lined with a proximal seal 18. The inlet housing 16 may
also include a distal end 21 that may include a flange 22 that may
be used to couple the inlet housing 16 to the main housing body 23
of the housing assembly 15 by way of a plurality of an attachment
mechanism such as mechanical fasteners 24, welding, or other
attachment mechanisms known by one skilled in the art. The inlet
housing 16 may also include an inlet 25 having an inlet axis
26.
[0026] The main housing body 23 may also include a proximal end 27
that may include a flange 28 that may be connected to the flange 22
of the inlet housing 16 as shown in FIG. 1. The proximal end 27 of
the main housing body 23 may be lined with a middle seal 31. The
purposes of the proximal and middle seals 18, 31 will be described
below in connection with the plunger 14. Continuing with the
description of the main body housing 23, the main housing body 23
may also include a distal end 32 that may be connected to an outlet
body 33 by way of one of the aforementioned attachment mechanisms
such as mechanical fasteners 34. The outlet body 33 may include a
flange 35 for accommodating the fasters 34. Further, the outlet
body 33 may be equipped with an annular groove 36 for accommodating
a ring seal 37 as shown in FIG. 1.
[0027] The discharge valve assembly 11 may include a discharge
valve head 38 that may be connected to a shaft 41. The shaft 41 may
be received in a hub 42 that is connected to a retainer 43. The hub
42 may accommodate a spring or biasing member 44 for biasing the
discharge valve head 38 against the discharge valve seat 45. The
spring 44 may also surround the hub 42. Other biasing schemes will
be apparent to those skilled in the art. A discharge valve seat 45
may be part of a discharge valve sleeve 46 which may include a
distal flange 47 that is trapped between the outlet body 33 and the
main housing body 23 as shown in FIG. 1. The discharge valve sleeve
46 may also include an annular slot 48 for accommodating a ring
seal 51. The housing assembly 15 also defines a housing bore 67
which becomes filled with fluid to be discharged through the outlet
12. The filling of the housing bore 67 with fluid will be described
in connection with FIG. 4 below.
[0028] Turning to the plunger 14, the plunger 14 may include a
proximal end 52 that may be coupled to an actuator 53 as shown in
phantom in FIG. 1. The flange 59 may be used for this coupling. The
actuator 53 may be a motor, either electric, internal combustion or
hydraulic with the requisite linkages needed to move the plunger 14
in a reciprocating fashion as illustrated in FIGS. 1, 2 and 4. The
plunger 14 may also include a distal end 54 that may be detachably
coupled to a valve seat 55 to facilitate replacement of the valve
seat 55 if the valve seat were to wear. In the embodiment shown,
the outlet valve seat 55 is threadably connected to the distal end
54 of a sidewall 57 of the plunger 14. Of course, other means for
attaching the outlet valve seat 55 to the sidewall 57 will be
apparent to those skilled in the art. The outlet valve seat 55 may
also be unitary or integral with the sidewall 57. The outlet valve
head 56 can sealably engage the valve seat 55 when the outlet valve
13 is in the closed position as shown in FIG. 1.
[0029] The sidewall 57 of the plunger 14 may also include at least
one opening 58. When more than one openings 58 are provided, the
openings 58 may be disposed circumferentially along the sidewall
along a common region or disposed offset from one another. The
sidewall 57 may define a plunger bore 61. Fluid may enter the
plunger bore 61 through the inlet 25 and at least one opening 58
thereby loading the plunger 14 with fluid. The outlet valve head 56
may be connected to a distal end of a rod 62 which, in turn, is
connected to a piston 63 circumferentially disposed about the
proximal end of the rod 62. The rod 62 is shown extending axially
through the plunger bore 61. The piston 63 may engage the interior
64 of the sidewall 57. However, the piston 63 may also include a
metered passageway 65. For example, the metered passageway may
include one or more axial bores formed in the piston 63. The
purpose of the metered passageway 65 is to permit fluid trapped in
the proximal cavity 66 to pass through the metered opening 65 as
the outlet valve assembly 13 moves from the open position shown in
FIGS. 4-5 to the closed position shown in FIG. 1. In other words,
fluid disposed within the plunger 14 and, more particularly, fluid
trapped in the proximal cavity 66 in combination with the metered
passageway 65 may act as a damper to the closing of the outlet
valve head 56 and prevent the outlet valve head 56 from engaging
the outlet valve seat 15 with excessive force. This dampening of
the closing action of the outlet valve assembly 13 can facilitate
the reduction of wear and tear on the outlet valve head 56 and the
outlet valve seat 55. Thus, at least one of the outlet valve head
56, the rod 62, the piston 63, and the metered opening 65 can
provide a dampening effect when the outlet valve assembly 13 is
closed. Further, the outlet valve head 56 may be detached from the
rod 62. For example, the outlet valve head 56 may be threadably
connected to the rod 62. Other means for attaching the outlet valve
head 56 to the rod 62 will be apparent to those skilled in the art
and the two components may be unitary in structure as well.
[0030] In FIG. 2, the plunger 14 has been moved to the right to a
dispense position from the static position of FIG. 1. When in the
dispense position, fluid disposed in the housing bore 67 has been
pressurized by the rightward of movement of the plunger 14 to form
a compression chamber out of a portion of the housing bore 67 as
the outlet valve head 56 moves towards the discharge valve head 38.
The reader will note that when the pressure in the housing bore 67
has increased beyond a threshold pressure to permit the discharge
valve head 38 to overcome the bias of the spring 44 and become
separated from the discharge valve seat 45. Thus, fluid flows from
the housing bore 67 past the discharge valve head 38 and through
one or more passageways 68 in the retainer 43 before exiting the
pump 10 through the outlet 12. Pressure is able to be increased in
the housing bore 67 due to the presence of the middle seal 31 which
provides a seal between the sidewall 57 of the plunger 14 and the
main housing body 23 or, more specifically, the proximal end 27 of
the main housing body 23 in combination with the rightward movement
of the plunger 14.
[0031] FIG. 3 illustrates the separation between the discharge
valve seat 45 and the discharge valve head 38. As shown in FIG. 3,
the discharge valve head 38 may include a frusto-conical section 71
that is configured to sealably engage the similarly configured
discharge valve seat 45 when the discharge valve assembly 11 is in
the closed position as shown in FIG. 1. FIGS. 3 and 4 also
illustrate the ease in which the discharge valve assembly 11 can be
replaced. The outlet body 33 may be easily removed by removing the
fasteners 34. Then, the retainer 43 may be disconnected, or in the
example shown, unscrewed from the discharge valve sleeve 46 thereby
enabling the retainer 43, spring 44 and discharge valve head 38 to
be removed through the distal end 32 of the main housing body 23.
Then, the discharge valve sleeve may be disconnected or, in the
example shown, unscrewed from the threaded inner surface 69 of the
housing bore 67.
[0032] In FIG. 4, the pump 10 is shown in a reload position as the
plunger 14 is being moved to the left in the shown orientation away
from the dispense position of FIG. 2. The leftward movement of the
plunger 14 decreases the pressure in the housing bore 67. A
decrease in the pressure in the housing bore 67 below the threshold
pressure can permit the discharge valve head 38 to close because of
bias of the spring 44 and re-engage the discharge valve seat 45.
Further, the lower pressure in the housing bore 67 can permit the
outlet valve assembly 13 to open as shown in FIG. 4. Specifically,
during the leftward movement of the plunger 14, the pressure in the
housing bore 67 can be less than the pressure within the plunger
bore 61 of the plunger 14 thereby causing a pressure difference to
allow the outlet valve head 56 to become unseated from the outlet
valve seat 55 as shown in FIG. 4. The outlet valve head 56 may
include a frusto- conical section that is configured to sealably
engage a similarly configured face of the outlet valve seat 55 when
the discharge valve assembly 11 is in the closed position as shown
in FIG. 1. While the outlet valve seat 55 is shown in the form of a
replaceable liner connected to the plunger sidewall 57, those
skilled in the art will realize that the outlet valve seat 55 may
be integrally connected to the sidewall 57 of the plunger 14.
[0033] Referring to FIGS. 1, 2 and 4, in one example, a replaceable
cylindrical liner 73 may line the housing bore 67 and, accordingly,
reduces the effective outer diameter of the housing bore 67 (or the
effective inner diameter of the main housing section 23).
Therefore, one way to change the volume of the housing bore 67 is
to change the replaceable liner 73 with a liner that is either
thicker or thinner than the liner 73. Hence, the capacity of the
pump 10 can be altered by simply changing the liner 73. This can be
achieved in one of two ways. Perhaps one way would be to remove the
fasteners 34 and outlet body 33. Then, the retainer 43 can be
removed before the discharge valve sleeve 46 and discharge valve
head 38 can be removed together thereby exposing the sleeve 73
which may be secured to the main housing body 23 via a threaded
connection or another connection that will be apparent to those
skilled in the art. Also, the sleeve 73 may simply be snugly
accommodated or friction fitted within the housing bore 67 as it is
trapped between the middle seal 31 and the discharge valve sleeve
46 as shown in FIGS. 1, 2 and 4.
[0034] The reader will note that the inlet axis 26 is perpendicular
to or at least substantially perpendicular to a pump axis or
plunger axis 19. Fluid enters the pump 10 through the inlet 25 and
then enters the plunger 14 through the opening 58. After fluid
passes through the opening 58 and into the plunger bore 61, the
fluid travels linearly through the plunger 14, around the outlet
valve head 56 and then linearly into the housing bore 67. During a
dispense stroke as illustrated in FIG. 2, high pressure fluid is
then ejected axially past the discharge valve assembly 11 and
axially out through the outlet 12. Thus, once the fluid has entered
the pump 10, it travels in a more or less linear fashion through
the pump 10 and out through the outlet 12.
[0035] FIG. 5 illustrates the outlet valve assembly 13 in an open
or reload position as the outlet valve head 56 has been lifted off
of the seat 55 as the plunger 14 moves to the left. As noted above,
the discharge valve seat 55 may be threadably secured to the
sidewall 57 of the plunger 14 and, of course, other means for
connecting the seat 55 to the sidewall 57 will be apparent to those
skilled in the art, in addition to making the sidewall 57 and seat
55 a single integral part.
[0036] Returning briefly to FIG. 4, as the plunger 14 is retracted
to the left thereby causing the pressure within the housing bore 67
to be reduced and the outlet valve assembly 13 to be opened, fluid
will flow through the open outlet valve assembly 13 to recharge the
housing bore 67 with fluid. One or more radial orifices 60 may be
formed in the hub 42 to allow fluid to pass therethrough. Without
one or more radial openings in the hub 42, a vacuum can be created
in the space occupied by the spring 44. Such a vacuum effect could
hinder the closure of the discharge valve head 38 against the valve
seat 45. Using one or more radial orifices 60 and controlling the
size of the one or more radial orifices 60 can be used to
advantageously dampen the closing of the discharge valve head 38
against the seat 45. Similarly, as discussed above, as the outlet
valve head 56 is closed against the outlet valve seat 55, the
dampening feature provided by the rod 62, piston 63 and metered
opening 65 provides a dampening effect thereby providing a less
violent collision between the outlet valve head 56 and the outlet
valve seat 55 which extends the useful life of both components.
[0037] Finally, because the pump 10 delivers fluid to the plunger
bore 61 before the fluid is transferred to the housing bore 67 and
out through the outlet 12, the pressurized fluid is delivered
through the outlet 12 in a linear fashion which may reduce stresses
against various parts of the pump thereby reducing the chances of
pump failure.
[0038] FIGS. 6 and 7 illustrate the coupling of three and five
pumps 10 respectively together for increased capacity. The pumps 10
of FIGS. 6-7 are connected in parallel and therefore, regardless of
whether the liners 73 are of the same or different thicknesses,
only the capacity will be increased, not the output pressure. As
shown in FIG. 7, a single actuator 53 may be used for the entire
group of pumps 10 or, in the alternative, individual actuators (not
shown) may be utilized. The pumps 10 may be coupled together by
various means, which will be apparent to those skilled in the
art.
[0039] Turning to FIG. 8, the relationship between the fluid
pressure in the housing bore 67 and the position of the plunger 14
is illustrated. Specifically, the x-axis represents time (t) and
the y-axis represents fluid pressure (p) in the housing bore 67.
The pressure values in the housing bores 67 are represented by the
line 75 and the position of the plunger is represented by the line
76. The point 77 along the x-axis represents the plunger 14 in the
far left position shown in FIG. 1 where the housing bore 67 is
loaded with fluid. The apex 78 of the plunger curve or line 76
represents the plunger in the far right position shown in FIG. 4.
Thus, as the plunger moves from the position shown in FIG. 1 as
represented by the point 77 in FIG. 8, the pressure increases to a
maximum pressure 79 which, within a certain time period, will open
the discharge valve assembly 11 thereby causing the pressure to
drop as shown in FIG. 8. The point 81 represents the plunger 14
being retracted and moved back to the left as shown in FIG. 1. As
the plunger 14 is retracted, the pressure within the housing bore
67 is at a minimum, thereby opening the outlet valve assembly 13 as
explained above.
INDUSTRIAL APPLICABILITY
[0040] A modular plunger pump is disclosed that can be used in a
side-by-side configuration to build multiple pump units. Each
individual pump includes a housing having a housing bore for
receiving a slidable plunger. The plunger includes a piston bore
and a sidewall opening in communication with the pump inlet. Low
pressure fluid passes from the inlet into the piston bore of the
plunger during a retracting or reloading stroke of the plunger. The
pump inlet may be oriented in a perpendicular fashion to the
plunger or main pump axis. Pressure of the fluid within the plunger
bore can build beyond a threshold pressure to overcome the biasing
of an outlet valve assembly in the closed position in order to urge
the outlet valve assembly to move away from its closed position.
Pressure from the pump inlet is then communicated out of the
plunger through the outlet valve assembly disposed at a distal end
of the plunger and into a housing bore where continued movement of
the plunger in the compression direction within the housing bore
pressurizes the fluid. During such a compression or dispense
stroke, the fluid in the housing bore is pressurized to a
sufficiently high pressure beyond a threshold pressure to open a
discharge valve assembly which is in communication with an
outlet.
[0041] The output capacity of the disclosed pumps may be altered by
changing the lining of the housing bore with the lining of a
different thickness. Thus, the volume of the housing bore can be
increased or decreased rather easily as described above. The
closure of the discharge valve assembly and the outlet valve
assembly may also be dampened. Specifically, with respect to the
outlet valve assembly, the outlet valve head may be coupled to a
piston with a metered passageway that allows fluid to flow through
the piston as the outlet valve head moves towards and engages the
outlet valve seat. In contrast, the closure of the discharge valve
head against the discharge valve seat may be dampened by fluid
entering the housing bore through the outlet valve assembly as the
plunger is retracted.
[0042] A method of pumping hydraulic fracturing fluid down a
wellbore is also disclosed using one of the disclosed pumps. The
method may include retracting the plunger away from the outlet in
an expansion direction such that the openings formed in the plunger
wall can communicate with the inlet to open the outlet valve
assembly and provide communication between the pump inlet and the
housing bore through the plunger and the open outlet valve assembly
of the plunger. The method may then include moving the plunger
towards the discharge valve assembly thereby closing the outlet
valve assembly disposed at the distal end of the plunger and
causing the fluid disposed in the housing bore to become
pressurized thereby eventually opening the discharge valve
assembly. The method may also include dispensing fluid through the
open discharge valve assembly and the outlet.
[0043] In another aspect, a method of pumping hydraulic fracturing
fluid down a well bore may, in a more simplified manner, include
biasing the discharge valve head against the discharge valve seat,
providing communication between the pump inlet and the housing
bore, moving the plunger towards the discharge valve head thereby
pressurizing a portion of the housing bore disposed between the
plunger and the discharge valve assembly thereby opening the
discharge valve assembly and dispensing fluid through the opened
discharge valve assembly and the outlet. The method may also
include dampening an engagement between the discharge valve head
and the discharge valve seat by releasing pressurized fluid
disposed in the hub and between the distal end of the shaft and the
proximal side of the retainer to provide additional pressure in the
housing bore as the discharge valve head closes against the
discharge valve seat. A radial orifice in the hub can be utilized
for releasing this pressurized fluid.
[0044] Still further, the method may further include replacing the
discharge valve seat and/or the discharge valve head by removing
the outlet from the housing assembly, removing the retainer from
the discharge valve sleeve, removing the discharge valve sleeve and
discharge valve head from the housing assembly, providing a new or
repaired discharge valve sleeve and/or a new or repaired discharge
valve head, coupling the new or repaired discharge valve sleeve to
the housing assembly, inserting the new or repaired discharge valve
head into the discharge valve sleeve, coupling the retainer to the
discharge valve sleeve and placing the hub over the shaft over the
discharge valve head and recoupling the outlet to the housing
assembly.
[0045] Another method may include retracting the plunger away from
the discharge valve assembly to open the outlet valve assembly and
provide communication between the inlet and the housing bore
through the plunger. The method may further include moving the
plunger towards the discharge valve assembly thereby closing the
outlet valve assembly, pressurizing the housing bore disposed
between the outlet valve assembly and the discharge valve assembly
and opening the discharge valve assembly. The method may then
further include dispensing fluid through the open discharge valve
assembly and the outlet. The method may also include dampening an
engagement between the outlet valve head and the outlet valve seat
as the outlet valve assembly closes by restricting flow of fluid
from a proximal side of the piston, through a metered passageway,
through the piston and to the distal side of the piston as the
piston moves towards the proximal end of the plunger.
[0046] Methods of replacing the outlet valve head and outlet valve
seat are also disclosed that include withdrawing the plunger from
the proximal end of the housing, unscrewing the outlet valve head
from the distal end of the rod, screwing a new outlet valve head
onto the distal end of the rod and inserting the plunger back into
the proximal end of the housing. To replace the outlet valve seat,
after withdrawing the plunger from the proximal end of the housing,
the outlet valve head, rod and piston are pulled through the distal
end of the plunger, the outlet valve seat is unscrewed from the
distal end of the sidewall of the plunger and replaced with a new
outlet valve seat. Then the piston, rod and outlet valve head are
reinserted back through the distal end of the plunger until the
outlet valve head engages the new outlet valve seat. The plunger is
then reinserted through the proximal end of the housing.
* * * * *