U.S. patent application number 13/765591 was filed with the patent office on 2013-08-15 for durable pumps for abrasives.
This patent application is currently assigned to SCHLUMBERGER TECHNOLOGY CORPORATION. The applicant listed for this patent is SCHLUMBERGER TECHNOLOGY CORPORATION. Invention is credited to DAVID ESLINGER.
Application Number | 20130209225 13/765591 |
Document ID | / |
Family ID | 45402665 |
Filed Date | 2013-08-15 |
United States Patent
Application |
20130209225 |
Kind Code |
A1 |
ESLINGER; DAVID |
August 15, 2013 |
DURABLE PUMPS FOR ABRASIVES
Abstract
Durable pumps for abrasives are provided. An example centrifugal
pump stage for subsurface operation has a thrust washer located
inside the circumference of an outboard clearance seal between an
impeller shroud and the diffuser. Relocation of the thrust washer
allows the clearance seal to protect the thrust washer from
abrasives. A centrifugal action of an outboard seal lip effects a
separation of the particles from the fluid nearest the gap of the
outboard seal and drives the particles away from the gap of the
outboard seal. When an abrasive particle in the leakage flow does
clear the outboard seal, the particle is readily flushed across the
thrust washer by the leakage flow to the central fluid inlet to
prevent wear of the thrust washer. In an implementation, the inside
diameter of the thrust washer is approximately flush with the bore
of a central fluid inlet of the pump stage.
Inventors: |
ESLINGER; DAVID;
(COLLINSVILLE, OK) |
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Applicant: |
Name |
City |
State |
Country |
Type |
CORPORATION; SCHLUMBERGER TECHNOLOGY |
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US |
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Assignee: |
SCHLUMBERGER TECHNOLOGY
CORPORATION
SUGAR LAND
TX
|
Family ID: |
45402665 |
Appl. No.: |
13/765591 |
Filed: |
February 12, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13174343 |
Jun 30, 2011 |
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13765591 |
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61360431 |
Jun 30, 2010 |
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61365695 |
Jul 19, 2010 |
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Current U.S.
Class: |
415/104 ;
29/888.024 |
Current CPC
Class: |
F04D 1/06 20130101; F04D
29/167 20130101; Y10T 29/49243 20150115; F04D 13/10 20130101; F04D
7/04 20130101 |
Class at
Publication: |
415/104 ;
29/888.024 |
International
Class: |
F04D 1/06 20060101
F04D001/06 |
Claims
1. A pump stage for application in a subsurface hydrocarbon well,
comprising: a diffuser; an impeller; a thrust washer; and an
outboard seal formed between a surface of the impeller and a first
surface of the diffuser and located radially outward from an
outside periphery of the thrust washer with respect to a central
axis of the pump stage.
2. The pump stage of claim 1, wherein the outboard seal protects a
pump component from particles in a leakage flow of a fluid being
pumped, wherein the pump component is selected from a group
consisting of the thrust washer and a balance ring seal.
3. The pump stage of claim 1, further comprising an outboard seal
lip of the impeller; wherein a surface of the outboard seal lip at
an outside diameter of the outboard seal lip engages a second
surface of the diffuser to prevent particles in a fluid being
pumped from bypassing a centrifugal action of the outside periphery
of the outboard seal lip.
4. The pump stage of claim 3, wherein when the impeller rotates a
centrifugal action of the outboard seal lip impels a fluid near a
gap of the outboard seal to move radially outward from the gap of
the outboard seal; and wherein when the fluid contains particles
the centrifugal action of the outboard seal lip effects a
separation of the particles from the fluid nearest the gap of the
outboard seal and drives the particles away from the gap of the
outboard seal.
5. The pump stage of claim 1, wherein a gap of the outboard seal
and a clearance around the thrust washer form a path for a leakage
flow comprising a fluid flow from the impeller back to a central
fluid inlet of the pump stage; wherein the outboard seal restricts
the leakage flow through the path more than the clearance around
the thrust washer restricts the same leakage flow; and wherein when
a particle in the leakage flow follows the path and clears the
outboard seal the particle is readily flushed across the thrust
washer by the leakage flow to the central fluid inlet to prevent a
wear of the thrust washer.
6. The pump stage of claim 1, wherein an inside diameter of the
thrust washer is approximately flush with an outside diameter of a
central fluid inlet of the pump stage; and wherein the outboard
seal is approximately flush with an outside diameter of the thrust
washer.
7. The pump stage of claim 1, wherein an inside cylindrical surface
of the thrust washer at an inside diameter of the thrust washer is
flush with a bore of a fluid inlet of the pump stage.
8. The pump stage of claim 7, wherein the inside cylindrical
surface of the thrust washer is in contact with fluid in the fluid
inlet of the pump stage.
9. The pump stage of claim 1, wherein a diameter of the outboard
seal determines a volume of a first fluid cavity on a first side of
the impeller to equalize a first fluid pressure on the first side
of the impeller with a second fluid pressure on a second side of
the impeller; and wherein equalizing the fluid pressures on the
first side and the second side of the impeller reduces a friction
of the impeller on the thrust washer.
10. The pump stage of claim 9, wherein the diameter of the outboard
seal is reduced in order to equalize the fluid pressures on the
first side and the second side of the impeller; and wherein a
diameter of the thrust washer is reduced to less than an inside
diameter of the outboard seal.
11. The pump stage of claim 10, wherein the reduced diameter of the
thrust washer and a consequent reduced surface area of the thrust
washer reduces an overall friction of the impeller on the thrust
washer.
12. The pump stage of claim 10, wherein the reduced diameter of the
thrust washer reduces a moment arm of a braking torque acting
between the impeller and the thrust washer.
13. An impeller for a submersible pump for subsurface pumping of a
fluid, comprising: a circular pump component at a first radius from
a center of rotation of the impeller; and a surface radially
outboard of the circular pump component and at a second radius
greater than the first radius, the surface forming an outboard seal
with a diffuser at the second radius to protect the circular pump
component from particles in a leakage flow of the fluid being
pumped.
14. The impeller of claim 13, wherein the circular pump component
is selected from a group consisting of a thrust washer and a
balance ring seal.
15. The impeller of claim 13, further comprising a lip on the
impeller, the lip possessing multiple surfaces engaging the
diffuser including the surface forming the outboard seal; a first
surface of the lip to engage a first surface of the diffuser to
form the outboard seal; a second surface of the lip radially
outward from the first surface of the lip, the second surface to
engage a second surface of the diffuser to impel the fluid away
from a gap opening of the outboard seal; and wherein when the fluid
contains particles a centrifugal action of the second surface of
the lip drives the particles away from the gap opening of the
outboard seal.
16. The impeller of claim 15, wherein when the lip rotates with the
impeller, a centrifugal action of the second surface of the lip
causes a separation of the particles away from the fluid nearest
the gap opening of the outboard seal.
17. The impeller of claim 15, wherein when the lip rotates with the
impeller, the lip impels the fluid in a circular motion; and
wherein when the fluid contains particles a centrifugal force
imparted by the circular motion separates the particles away from
the fluid nearest the gap opening of the outboard seal.
18. The impeller of claim 14, wherein a gap opening of the outboard
seal and a clearance between the thrust washer and the diffuser
form a path for a leakage flow in the submersible pump from the
impeller back to a central fluid inlet of the submersible pump;
wherein a centrifugal action of the lip restricts the leakage flow
through the path more than the clearance between the thrust washer
and the diffuser restricts the same leakage flow; and wherein when
a particle in the leakage flow follows the path and clears the
outboard seal the particle is readily flushed across the thrust
washer by the leakage flow to the central fluid inlet to prevent a
wear of the thrust washer.
19. A method, comprising: constructing a centrifugal pump stage for
a multi-stage submersible pump for a subsurface hydrocarbon well,
the pump stage including an impeller, a diffuser, and a thrust
washer; and locating the thrust washer radially inboard in relation
to an impeller-to-diffuser clearance seal of the pump stage.
20. The method of claim 19, further comprising constructing an
impeller projection to engage multiple surfaces of the diffuser;
wherein a first surface of the impeller projection engages a first
surface of the diffuser to form the impeller-to-diffuser clearance
seal; wherein a second surface of the impeller projection engages a
second surface of the diffuser to accelerate a circular motion of a
fluid near a gap of the impeller-to-diffuser clearance seal; and
wherein when the fluid contains particles a centrifugal force
imparted by the circular motion separates the particles away from
the gap.
Description
RELATED APPLICATIONS
[0001] This continuation patent application claims the benefit of
priority to U.S. patent application Ser. No. 13/174,343 to
Eslinger, filed Jun. 30, 2011 and entitled "Durable Pump for
Abrasives," which is incorporated herein by reference in its
entirety, which in turn claims priority to U.S. Provisional Patent
Application No. 61/365,695, filed Jul. 19, 2010, and entitled,
"Centrifugal Pump with Increased Abrasion Resistance," and to U.S.
Provisional Patent No. 61/360,431, filed Jun. 30, 2010, and
entitled, "Device and Means to Reduce Downthrust in a Multistage
Centrifugal Pump," both of which are incorporated herein by
reference in their entirety.
BACKGROUND
[0002] Oilfields sometimes use electric submersible pumps staged in
series to pump downhole fluids. A number of centrifugal pump stages
can be stacked together along their axial direction for ganged lift
in a subsurface environment. Such subsurface multistage pumps are
frequently employed to move fluids consisting of liquid hydrocarbon
mixtures that may have some mixed and suspended earth solids. The
fluid may also contain gaseous components and water. Particles and
chunks of rock and sand are usually present to some degree. Such
heterogeneous "liquid sandpaper" may result in cavitation and
abrasion issues for pumps, especially if the solids cause deposits
to build up against some surfaces of the pump or if the fluid
itself has a slurry-like consistency. The viscosity and other flow
characteristics of a particular liquid mixture may result in high
velocity flow of the abrasive fluid around certain pump parts.
Impellers used in downhole centrifugal pumps experience significant
abrasion of the downthrust washers (hereinafter, "thrust washers")
when pumping fluids containing abrasives. Thus, the art of pump
design aims to minimize abrasion and prolong the life of the pump.
The particular composition and behavioral characteristics of the
abrasive fluid to be pumped often allow particular pumps to be
custom-designed and optimized for particular types of unrefined
fluids.
SUMMARY
[0003] Durable pumps for abrasives are provided. An example
centrifugal pump stage for subsurface operation has a thrust washer
located inside the circumference of an outboard clearance seal
betwe en an impeller shroud and the diffuser. Relocation of the
thrust washer allows the clearance seal to protect the thrust
washer from abrasives. A centrifugal action of an outboard seal lip
effects a separation of the particles from the fluid nearest the
gap of the outboard seal and drives the particles away from the gap
of the outboard seal. When an abrasive particle in the leakage flow
does clear the outboard seal, the particle is readily flushed
across the thrust washer by the leakage flow to the central fluid
inlet to prevent wear of the thrust washer. In an implementation,
the inside diameter of the thrust washer is approximately flush
with the bore of a central fluid inlet of the pump stage. This
summary section is not intended to give a full description of
durable pumps for abrasives. A detailed description with example
implementations follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a diagram of an example stage of a multistage
subsurface pump for pumping fluids containing abrasives.
[0005] FIG. 2 is a diagram of example inboard thrust washers for a
subsurface pump for abrasives.
[0006] FIG. 3 is a diagram of example reduction in diameter of an
inboard thrust washer.
[0007] FIG. 4 is a diagram of example reduction in diameter of a
thrust washer to balance pressure areas to reduce friction.
[0008] FIG. 5 is a diagram of an example reduction in thrust washer
diameter to decrease friction and reduce power loss.
[0009] FIG. 6 is a diagram of an example reduction in thrust washer
diameter to decrease moment arm of a braking torque to reduce power
loss.
[0010] FIG. 7 is a flow diagram of an example method of making an
abrasion-resistant subsurface pump.
[0011] FIG. 8 is a flow diagram of an example method of increasing
the durability and efficiency of an abrasion-resistant pump.
DETAILED DESCRIPTION
[0012] Overview
[0013] This disclosure describes durable pumps for abrasives. The
described pumps provide higher wear and longer life than
conventional designs, especially when pumping subsurface fluids
containing some solids that tend to be abrasive when pumped, or
when pumping slurries. FIG. 1 shows a cross-section of a
centrifugal pump stage 100 of a multistage submersible pump stack
102. The multistage submersible pump stack 102 includes a number of
the centrifugal pump stages 100 stacked together along their axial
direction for ganged lift to generate axial fluid flow 104 in a
subsurface environment. FIG. 2 shows example inboard thrust
washers. FIGS. 3-6 show reduction of the diameter of example thrust
washers, and associated benefits. FIGS. 7-8 show example methods of
increasing the durability of pumps for abrasive fluids.
Example System Environment
[0014] Electric submersible pumps for abrasive fluids usually have
at least one surface that is an impeller housing, or "shroud,"
i.e., a solid part of the impeller assembly extending radially
outward from a more central hub to strengthen and attach the
impeller blades on one side, and also serving to screen or shield
the impeller blades, at least in part, from the fluid on the other
side of the shroud, since the shroud is solid. Impeller blades are
typically attached to the shroud, and the shroud is typically
attached to a hub that receives the rotational drive power of the
pump, or, the shroud is an extension of the hub itself. Such a
shroud may "underlie" the bottom sides of the impeller blades, or
two shrouds may enclose both the top and bottom sides of the
impeller blades in a "closed-impeller" or "enclosed" design in
which only the radial ends of the impeller blades are open, as
opposed to open-style impeller blades that are exposed to the fluid
being pumped on all sides of the blades. Open-style impellers
(without a shroud) are more susceptible to abrasive wear than a
shrouded impeller, because high velocity fluid on the impeller
blades is in close proximity to the casing walls ("diffuser" or
housing), creating rotating vortices that accelerate wear when
abrasives are present in the fluid.
[0015] Centrifugal pumps for moving fluids that may have abrasive
properties typically incorporate a single shroud, located on the
bottom of the impeller, or an enclosed design with both top and
bottom shrouds. In an abrasive setting, the shroud(s) also provide
additional structural support and reinforcement to protect against
blade collapse or deformation. Such enclosed or semi-open impeller
designs are well suited for handling solids in applications where
the blades might encounter high impact loads from rocks and solids.
A semi-open impeller also has an ability to pass solids in a manner
similar to that of an open impeller type. With a single shroud the
semi-open impeller is also relatively easy to manufacture.
[0016] High axial thrust is the primary drawback of semi-open and
enclosed impeller designs: the rotating impeller creates a net
fluid flow 104 along the axial direction but also creates large
reaction forces, which thrust the shrouded impeller back in the
opposite direction of the axial fluid flow. On a semi-open
impeller, the entire backside surface of the shroud is subject to
the full impeller discharge pressure. The front side of the shroud
is at suction pressure at the eye of the impeller, where the fluid
is inlet, and increases along the impeller radius due to
centrifugal action.
[0017] The differential between the pressure profiles along the two
sides of the shroud creates the axial thrust imbalance, referred to
herein as downthrust. The downthrust can be countered with a thrust
washer, which radially supports the backside of the shroud. There
is also an efficiency loss due to disk friction caused by the
impeller shroud turning in close proximity to the stationary casing
wall. The downthrust forces are resisted by thrust washers on each
stage for floater style pumps. Impellers of the mixed-flow type
usually have balance rings which assist to keep these forces within
acceptable limits. However, radial-flow impellers do not have such
balance rings due to the need to minimize the stage axial length.
The height of the wear rings, thrust washers, or other balance
rings in the axial direction is of primary concern because this
height directly affects the overall height of each pump stage,
which is critical in many multistage pump designs. Therefore,
radial impellers tend to have high thrust loads which lead to high
mechanical friction power losses and a high thrust washer wear
rate.
[0018] In centrifugal pumps, a portion of the fluid exiting from
the rotating impeller characteristically leaks back to the pump
suction by traveling through the gap between the impeller shroud
and the casing. A semi-open impeller typically has wear rings or a
front seal to control this leakage. In some pump stage designs, the
outer edges of the thrust washer may perform this leakage-control
role. Thus, the thrust washer may also aim to provide a fluid
seal.
[0019] The thrust washers control recirculation through flow
restriction, and may also be used in conjunction with impeller
balance holes to control the axial thrust. However, the flow
restriction created by tight clearances between rotating and
stationary thrust washer faces causes very high local fluid
velocities and thus a high wear rate. Conventional thrust washers,
because they are subject to this high flow velocity, have a short
life span in an abrasive environment, even when hard materials and
treated surfaces are used.
[0020] The flow restriction at the thrust washer also causes solids
to dam up at this location. Conventionally, as shown in the top of
FIG. 2, an outboard thrust washer 202 is located radially outward
from an impeller-to-diffuser shroud clearance seal 204 or other
seal. Such a clearance seal 204 is typically a finely machined,
close-fitting, close-running, metal-to-metal interface between the
impeller shroud 206 and the diffuser (casing walls) 208 of the
pump. The conventional wisdom of this arrangement is to support the
impeller 210 against reactive forces from axial fluid flow 104,
supporting the impeller 210 around a ring that has a substantial
diameter under the impeller at some median radius of the impeller
shroud 206. But a shortcoming of the outboard thrust washer 202
arrangement is that abrasive particles carried by fluid leakage
from the impeller tip tend to accumulate at deposit location 212 in
FIG. 2. This build-up of abrasive particles is due to the fact that
the thrust washer axial clearance is larger than the radial
clearance of front seal action and therefore the front seal acts as
a particle dam. Accumulated abrasive particles rapidly wear the
outboard thrust washer 202.
[0021] The thrust created by the impeller 210 in each stage of a
submersible pump can be problematic in a variety of submersible
pump types, including pumps with mixed flow stages and pumps with
radial flow stages. In some floater style designs, for example, a
significant portion of power loss in the pump is due to thrust
friction occurring at an outer thrust washer due to relatively high
friction-induced torque at this radially outlying position. If the
outer thrust washer is removed from the floater style stage,
however, the lack of any seal functionality increases leakage
loss.
Example Pump and Impeller Design
[0022] As shown in the bottom part of FIG. 2, in one implementation
of a pump stage 100, an example pump impeller 214 has an inboard
thrust washer (pad, ring) 216 that is relocated inboard in relation
to a seal 204 that defines a boundary of a fluid chamber of the
diffuser (i.e., the stationary housing around the impeller). The
relocation of the inboard thrust washer 216 "behind" the seal 204
protects the inboard thrust washer 216 from abrasive fluids being
pumped and thus, from conventional abrasion and wear. The term
"inboard," as used herein, means "radially inward, toward, or
closer to the axial center of rotation of the pump," while
"outboard" means "radially outward, away from, or further from the
axial center of rotation of the pump."
[0023] The aforementioned seal 204 may be a wear ring, or may be a
finely machined, close-running interface between a rotating part of
the impeller 214, usually an impeller shroud 218, and the
stationary diffuser housing: i.e., an impeller shroud-to-diffuser
clearance seal 204. With regard to abrasive fluid, since the
protecting seal 204 is upstream from the inboard thrust washer 216
(with respect to fluid trying to return from the impeller 214 to
the pump inlet 220) the amount of abrasive particles reaching the
protected inboard thrust washer 216 is greatly reduced or
eliminated. In conventional designs, an outboard thrust washer 202
may be in direct contact or even fully immersed in the fluid being
pumped. The thrust washer 216 thus relocated and protected
counteracts and supports against reactionary downthrust forces
generated by the pumping impeller while providing higher wear and
longer life than in conventional pumps used for pumping abrasive
fluids in a multistage, subsurface environment.
[0024] In the same or another implementation, as shown in FIG. 3,
the diameter (size, or "ring-size") of a seal or a thrust washer at
the bottom (i.e., back) of the impeller is strategically reduced in
order to expose more surface area of the bottom impeller shroud to
the pressured fluid being pumped. In some designs a seal, wear
ring, or close-fitting interface between moving impeller and
stationary diffuser forms the extent of the fluid space under the
impeller, while in other designs the thrust washer 202 itself plays
this role. The thrust washer 202 will be used as an example for the
sake of description below, since it plays the additional role of a
"wear ring" type seal in some pumps.
[0025] As shown in the top part of FIG. 4, a conventional thrust
washer 202 defines the extent of a fluid chamber 402 at a bottom
impeller shroud 206. The top of the impeller 210 has a fluid
chamber 404 that exposes a greater amount of surface area at the
top of the impeller 210 to pressured fluid, resulting in a pressure
imbalance area 406, which thrusts the impeller 210 down into the
thrust washer 202, where friction results in power loss. Downthrust
forces tend to be high because pressure acting on the impeller
bottom shroud surface 206 is sealed at the outside diameter 408 of
the thrust washer 202, while pressure forces acting on the impeller
top shroud surface 410 are sealed at the diffuser hub inside
diameter 412.
[0026] In the bottom part of FIG. 4, reducing the diameter of the
conventional thrust washer 202 to a smaller diameter thrust washer
216 when designing and manufacturing a pump, increases the extent
of the bottom fluid chamber 414 and increases the amount of surface
area of the bottom impeller shroud 416 that is exposed to the
pressured fluid underneath. Referring to FIG. 4, reducing the
diameter of the thrust washer 216 effectively reduces the pressure
imbalance area 418, as given in Equation (1):
.DELTA.A=(.pi./4)(d.sub.1.sup.2-d.sub.2.sup.2) (1)
where d.sub.1 is the conventional outside diameter of the pressure
imbalance area 406 and d.sub.2 is the outside diameter of the
reduced pressure imbalance area 418. Reducing the pressure
imbalance area 418 in this manner increases the pressure at the
bottom impeller shroud 416 thereby lifting the impeller 420 off the
thrust washer 216 to some degree. The lift may not be a physical
movement of the impeller 420 off the thrust washer 216, but may be
a reduction in the net downthrust force acting on the impeller 420,
or a reduction in the normal force F.sub.n on the friction surface
of the thrust washer 216, thus sparing the thrust washer 216. The
friction on the surface of the thrust washer 216 may be
approximated by the dry friction expression in Equation (2):
F.sub.f.ltoreq..mu.F.sub.n (2)
where F.sub.f is the force of friction exerted by each surface on
the other, and is parallel to the surface in a direction opposite
to the net applied force; .mu. is the coefficient of friction,
which is an empirical property of the materials used to make the
thrust washer 216, and F.sub.n is the normal force exerted by each
surface on the other, directed perpendicular (normal) to the
surface.
[0027] The diameter of the thrust washer 216 (or other seal) can
thus be selectively reduced to strategically balance the exposed
surface area and pressure at the bottom of the impeller 420 with
the exposed surface area and pressure at the top of the impeller
420 to reduce friction and power loss. This balancing of pressures
at the top and bottom of the impeller 420 through seal or washer
size selection also provides additional benefits.
[0028] As shown in FIG. 5, in reducing the diameter of the
conventional thrust washer 202, the reduced diameter of the smaller
thrust washer 216 also reduces power loss because of less surface
area for friction to occur on the smaller thrust washer 216. The
reduction in surface area for friction to occur is given by
Equation (3), using the radii shown in FIG. 5:
.DELTA.A=.pi.[(r.sub.1.sup.2-r.sub.2.sup.2)-(r.sub.3.sup.2-r.sub.4.sup.2-
)] (3)
[0029] For a reduction in the outside diameter of a conventional
thrust washer 202 in which the new outside diameter of the smaller
thrust washer 216 still remains larger than the initial inside
diameter of the conventional thrust washer 202, the reduction in
surface area for friction to occur may be given by Equation
(4):
.DELTA.A=(.pi./4)(d.sub.1.sup.2-d.sub.2.sup.2) (4)
where d.sub.1 is the outside diameter of the conventional thrust
washer 202 and d.sub.2 is the outside diameter of the new, smaller
thrust washer 216.
[0030] Further, as shown in FIG. 6, since the radius of the circle
or ring defined by the conventional thrust washer 202 is reduced to
that of the new smaller thrust washer 216, the moment arm 602 of
the incidental braking force is reduced 604. The braking force is a
high-friction-induced torque acting between the rotating shroud and
the thrust washer 216, or between the stationary diffuser and the
thrust washer 216, depending on set-up, as the thrust washer 216
undesirably acts like elements of a disk brake. The frictional
torque is given by Equation (5):
.tau.=r.times.F (5)
where .tau. is the frictional braking torque, r is the moment arm
602 (or lever arm) and F is the friction force approximated by
Equation (2) above. Thus, the reduction in frictional braking
torque may be given by Equation (6), using the radii shown in FIG.
6:
.DELTA..tau.=F(r.sub.1-r.sub.2) (6)
[0031] Relocating the seal or thrust washer may also increase
efficiency of the pump and reduce wear by placing the thrust washer
216 or other seal where there is less agitation and turbulence in
the abrasive fluid and/or where there is improved laminar flow away
from closely interacting moving parts.
Example Methods
[0032] FIG. 7 is an example method 700 of making an
abrasion-resistant subsurface pump. In the flow diagram, the
operations are summarized in individual blocks.
[0033] At block 702, a pump for moving fluids containing abrasives
in a subsurface location is made, including an impeller, a casing,
and a thrust washer.
[0034] At block 704, a seal and a thrust washer are placed in
relation to each other to resist a flow of the abrasives to the
thrust washer.
[0035] FIG. 8 is an example method 800 of increasing the durability
and efficiency of an abrasion-resistant pump. In the flow diagram,
the operations are summarized in individual blocks.
[0036] At block 802, an impeller for pumping a fluid is made,
including a thrust washer for supporting the impeller and for
restricting a flow of the fluid.
[0037] At block 804, the diameter of the thrust washer is reduced
to balance a first pressure at the bottom of the impeller with a
second pressure at the top of the impeller, to reduce a friction of
the impeller on the thrust washer.
[0038] At block 806, the diameter of the thrust washer is reduced
to reduce a surface area subject to friction and to reduce a moment
arm of a braking torque on the impeller, to reduce power loss in
the pump.
CONCLUSION
[0039] Although exemplary systems and methods have been described
in language specific to structural features or techniques, the
subject matter defined in the appended claims is not necessarily
limited to the specific features or acts described. Rather, the
specific features and acts are disclosed as example forms of
implementing the claimed systems, methods, and structures.
* * * * *