U.S. patent application number 12/723774 was filed with the patent office on 2011-09-15 for pump assembly and method.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. Invention is credited to Lorenzo Bergamini, Ravindra Gopaldas Devi, Biao Fang, Rajesh Kumar Venkata Gadamsetty, Roderick Mark Lusted, Rosario Monteriso, Omprakash Samudrala.
Application Number | 20110223039 12/723774 |
Document ID | / |
Family ID | 44560176 |
Filed Date | 2011-09-15 |
United States Patent
Application |
20110223039 |
Kind Code |
A1 |
Fang; Biao ; et al. |
September 15, 2011 |
PUMP ASSEMBLY AND METHOD
Abstract
A pump assembly comprises a centrifugal pump configured to pump
a multiphase fluid, a suction conduit in fluid communication with
the centrifugal pump, and a discharge conduit in fluid
communication with the centrifugal pump. The pump further comprises
an eductor comprising one or more motive nozzles disposed within
the suction conduit. Wherein the one or more motive nozzles are
configured to introduce a motive fluid into the suction conduit and
toward the centrifugal pump along a suction direction roughly
co-directional with the suction conduit toward the centrifugal
pump. A method and a pump assembly for pumping a multiphase fluid
are also presented.
Inventors: |
Fang; Biao; (Clifton Park,
NY) ; Lusted; Roderick Mark; (Niskayuna, NY) ;
Samudrala; Omprakash; (Clifton Park, NY) ; Devi;
Ravindra Gopaldas; (Bangalore, IN) ; Bergamini;
Lorenzo; (Bari, IT) ; Gadamsetty; Rajesh Kumar
Venkata; (Bangalore, IN) ; Monteriso; Rosario;
(Trani, IT) |
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
44560176 |
Appl. No.: |
12/723774 |
Filed: |
March 15, 2010 |
Current U.S.
Class: |
417/54 ;
417/80 |
Current CPC
Class: |
F04D 9/06 20130101; F04F
5/10 20130101; F04B 23/14 20130101; F04F 5/46 20130101; F04D 31/00
20130101 |
Class at
Publication: |
417/54 ;
417/80 |
International
Class: |
F04D 9/06 20060101
F04D009/06; F04F 5/46 20060101 F04F005/46 |
Claims
1. A pump assembly for pumping a multiphase fluid, the pump
assembly comprising: a centrifugal pump configured to pump a
multiphase fluid; a suction conduit in fluid communication with the
centrifugal pump; a discharge conduit in fluid communication with
the centrifugal pump; and an eductor comprising one or more motive
nozzles disposed within the suction conduit; wherein the one or
more motive nozzles are configured to introduce a motive fluid into
the suction conduit and toward the centrifugal pump along a suction
direction roughly co-directional with the suction conduit toward
the centrifugal pump.
2. The pump assembly of claim 1, wherein at least one of the one or
more motive nozzles is disposed along an axis parallel to an axis
of the suction conduit.
3. The pump assembly of claim 1, wherein at least one of the one or
more motive nozzles is coaxial with the suction conduit.
4. The pump assembly of claim 1, wherein the eductor is in fluid
communication with the discharge conduit and is configured to
receive at least a portion of a discharge fluid.
5. The pump assembly of claim 4, wherein the centrifugal pump is a
multistage centrifugal pump.
6. The pump assembly of claim 4, further comprising a recirculation
apparatus disposed between the discharge conduit and the eductor,
the recirculation apparatus being configured to deliver the at
least a portion of the discharge fluid into the eductor.
7. The pump assembly of claim 4, further comprising a control valve
disposed between the eductor and the discharge conduit.
8. The pump assembly of claim 4, further comprising a detector for
detecting a gas volume fraction of one or more of the multiphase
fluid, and a mixture fluid of the motive fluid and the multiphase
fluid.
9. A method for pumping a multiphase fluid, the method comprising:
introducing a multiphase fluid into a centrifugal pump via a
suction conduit; receiving a discharge fluid from the centrifugal
pump via a discharge conduit; and introducing a motive fluid into
the multiphase fluid such that from initial contact of the
multiphase fluid and the motive fluid, both fluids move
unidirectionally along a flow path leading to the centrifugal
pump.
10. The method of claim 9, wherein the motive fluid being
introduced has a total pressure at least equal the total pressure
of the multiphase fluid in the suction conduit.
11. The method of claim 9, wherein the motive fluid has a lower gas
volume fraction than that of the multiphase fluid.
12. The method of claim 9, wherein the motive fluid is introduced
into the multiphase fluid via one or more motive nozzles.
13. The method of claim 12, wherein at least a portion of the
discharge fluid is used as the motive fluid.
14. The method claim 13, further comprising directing a portion of
the discharge fluid to a recirculation apparatus in fluid
communication with the one or more of the motive nozzles via a
conduit.
15. The method of claim 9, further comprising detecting a gas
volume fraction of one or more of the multiphase fluid, and a
mixture fluid of the motive fluid and the multiphase fluid in the
suction conduit.
16. The method of claim 15, wherein said detecting triggers a
control valve to regulate the introduction of motive fluid into the
multiphase fluid.
17. A pump assembly for pumping a multiphase fluid, the pump
assembly comprising: a plurality of centrifugal pumps configured to
pump a multiphase fluid; a suction conduit in fluid communication
with the plurality of the centrifugal pumps; a discharge conduit in
fluid communication with the plurality of the centrifugal pumps;
and an eductor comprising one or more motive nozzles disposed
within the suction conduit and configured to extend along a suction
direction of the multiphase fluid so as to introduce a motive fluid
into the suction conduit and toward the plurality of the
centrifugal pumps.
18. The pump assembly of claim 17, wherein at least one of the one
or more motive nozzles is disposed along an axis parallel to an
axis of the suction conduit.
19. The pump assembly of claim 17, wherein at least one of the one
or more motive nozzles is disposed along an axis having an acute
angle with an axis of the suction conduit.
20. The pump assembly of claim 17, wherein the eductor is in fluid
communication with the discharge conduit and is configured to
receive at least a portion of a discharge fluid.
21. The pump assembly of claim 17, wherein the plurality of
centrifugal pumps are configured in parallel.
22. The pump assembly of claim 17, wherein the plurality of
centrifugal pumps are configured in series.
Description
BACKGROUND
[0001] This invention relates generally to pump assemblies and
methods for pumping fluids. More particularly, this invention
relates to pump assemblies employing centrifugal pumps and methods
for pumping multiphase fluids.
[0002] Multiphase fluids, such as gaseous and liquid two-phase
fluids exist in many areas of technology, such as oil production.
Centrifugal pumps are often preferred when pumping multiphase
process fluids, due to their lower cost, smaller size, and
simplicity of operation and construction relative to other types of
pumps, for example twin screw pumps.
[0003] One drawback to the use of centrifugal pumps in the
operations involving multiphase process fluids, for example
petroleum-gas mixtures from a subsurface reservoir, is the
unintended segregation of the multiphase process fluid into its
liquid and gaseous components as a result of shear forces applied
to the multiphase process fluid by the rotating impellers of the
centrifugal pump. In some instances, a liquid phase separates from
the multiphase process fluid and moves to the periphery of the pump
impellers while the gaseous components of the multiphase process
fluid accumulate near the eyes of the impellers. As a result, the
performance of the centrifugal pump may decrease and eventually it
may no longer be possible to pump the multiphase process fluid
effectively. This behavior may become particularly acute for
multiphase process fluids characterized by a high gas volume
fraction.
[0004] Therefore, there is a need for new and improved pump
assemblies employing centrifugal pumps and methods for pumping
multiphase fluids.
BRIEF DESCRIPTION
[0005] A pump assembly for pumping a multiphase fluid is provided
in accordance with one embodiment of the invention. The pump
assembly comprises a centrifugal pump configured to pump a
multiphase fluid, a suction conduit in fluid communication with the
centrifugal pump, and a discharge conduit in fluid communication
with the centrifugal pump. The pump further comprises an eductor
comprising one or more motive nozzles disposed within the suction
conduit. Wherein the one or more motive nozzle are configured to
introduce a motive fluid into the suction conduit and toward the
centrifugal pump along a suction direction roughly co-directional
with the suction conduit toward the centrifugal pump.
[0006] A method for pumping a multiphase fluid is provided in
accordance with another embodiment of the invention. The method
comprises introducing a multiphase fluid into a centrifugal pump
via a suction conduit, receiving a discharge fluid from the
centrifugal pump via a discharge conduit, and introducing a motive
fluid into the multiphase fluid such that from initial contact of
the multiphase fluid and the motive fluid, both fluids move
unidirectionally along a flow path leading to the centrifugal
pump.
[0007] Another aspect of the invention further provides a pump
assembly for pumping a multiphase fluid. The pump assembly
comprises a plurality of centrifugal pumps configured to pump a
multiphase fluid, a suction conduit in fluid communication with the
plurality of the centrifugal pumps, and a discharge conduit in
fluid communication with the plurality of the centrifugal pumps.
The pump assembly further comprises an eductor comprising one or
more motive nozzles. The one or more motive nozzles are disposed
within the suction conduit and configured to extend along a suction
direction of the multiphase fluid so as to introduce a motive fluid
into the suction conduit and toward the centrifugal pump.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] These and other aspects, features, and advantages of the
present disclosure will become more apparent in light of the
subsequent detailed description when taken in conjunction with the
accompanying drawings in which:
[0009] FIG. 1 is a schematic diagram of a pump assembly in
accordance with one embodiment of the invention;
[0010] FIGS. 2-4 are schematic diagrams of arrangements of an
eductor and an suction conduit of the pump assembly shown in FIG. 1
in accordance with various embodiment of the invention;
[0011] FIG. 5 is a schematic diagram of the arrangement of an
eductor and an suction conduit of a pump assembly in accordance
with an embodiment of the invention; and
[0012] FIG. 6 shows experimental data obtained using a pump
assembly like that shown in FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0013] Embodiments of the present disclosure are described herein
with reference to the accompanying drawings. In the subsequent
description, well-known functions or constructions are not
described in detail to avoid obscuring the disclosure in
unnecessary detail.
[0014] FIG. 1 illustrates a schematic diagram of a pump assembly 10
for pumping a multiphase fluid 11 in accordance with one embodiment
of the invention. The multiphase fluid 11 comprises two or more
phases. In one embodiment, the multiphase fluid is a two phase
fluid comprising a gaseous fluid and a liquid fluid. In an
alternate embodiment, the multiphase fluid comprises at least three
phases; for example a gaseous phase, a liquid phase and a solid
phase. Examples of multiphase fluids include production streams
from oil wells, process fluids in chemical manufacturing, and the
like. In certain embodiments, the multiphase fluid may be a
gas-liquid two-phase fluid and may include one or more of bubble,
slug, transitional and mist flow type phases.
[0015] As illustrated in FIG. 1, the pump assembly 10 comprises a
centrifugal pump 12, a suction conduit 13, a discharge conduit 14,
a recirculation apparatus 15, and an eductor 16. In FIGS. 1-5 the
same element numbers are used for the same or similar components
unless specified otherwise.
[0016] It should be noted that the arrangements in FIG. 1 is merely
illustrative. In some applications, the pump assembly 10 may
comprise a plurality of centrifugal pumps 12 configured in parallel
or in serials. In various embodiments, each of the centrifugal
pumps 12 may be a radial flow pump, an axial flow pump, or a
mixed-flow type pump and may be configured for single stage or
multistage operation. The suction conduit 13 may be in fluid
communication with a multiphase fluid source (not shown) and
configured to deliver the multiphase fluid 11 from the multiphase
fluid source into the centrifugal pump 12. The action of the
centrifugal pump 12 on the multiphase fluid 11 results in the
formation of a discharge fluid (not shown), which may be removed
via discharge conduit 14.
[0017] In some applications, the discharge fluid may also be
multiphase and have a higher or same total pressure than that of
the multiphase fluid. In non-limiting examples, the discharge fluid
may be discharged from any stage of the centrifugal pump when the
centrifugal pump has a multistage configuration. Additionally,
since the multiphase fluid 11 passes through the centrifugal pump
12, the discharge fluid may have a lower gas volume fraction (GVF)
than that of the multiphase fluid.
[0018] For certain arrangements, the suction conduit 13 and/or the
discharge conduit 14 may be detachably assembled onto the
centrifugal pump 12 for delivering the multiphase fluid into and
the discharge fluid away from the centrifugal pump 12,
respectively. In other applications, the suction conduit 13 and/or
the discharge conduit 14 may be unitary with the centrifugal pump
12, for example, to function as a suction nozzle 24 (shown in FIG.
3) and a discharge nozzle (not shown) of the centrifugal pump 12,
respectively. For such a configuration, in some examples, one or
more additional conduits may be employed to deliver the multiphase
fluid into the centrifugal pump 12 via the suction conduit (suction
nozzle) 13 and/or deliver the discharge fluid away from the
centrifugal pump 12 via the discharge conduit (discharge nozzle)
14. In some examples, the term "unitary" indicate more than one
element may be integrated together by some known methods, such as
molding, welding and riveting, and may function as one element.
[0019] In the example illustrated in FIG. 1, the recirculation
apparatus 15 is disposed downstream from the centrifugal pump 12
and in fluid communication with the discharge conduit 14 for
receiving the discharge fluid from the centrifugal pump 12. The
eductor 16 is in fluid communication with a lower portion of the
recirculation apparatus 15 via a connection conduit 20.
[0020] In non-limiting examples, the recirculation apparatus 15 may
comprise a container 17 and a separator (not shown) disposed within
the container 17 for gas and liquid separation of the discharge
fluid. Non-limiting examples of the separator include a cyclone
separator and a static separator with enhanced gravity. In some
applications, the separator may not be employed and the discharge
fluid may be separated by gravity separation.
[0021] Thus, when the discharge fluid is delivered into the
container 17, the separator performs the gas and liquid separation
of at least a portion of the discharge fluid in the container 17,
so that a motive fluid 22 (shown in FIG. 2) may accumulate at the
lower portion of the container 17 for delivery into the eductor 16
while a fluid accumulated at an upper portion of the container 17
may be discharged out of the recirculation apparatus with/without
other portions of the discharge fluid for certain applications via
a conduit 19.
[0022] In some examples, due to the higher total pressure of the
discharge fluid and the presence of the separator, the motive fluid
may also have a higher total pressure and a lower GVF than those of
the multiphase fluid. Additionally, in some applications, since the
discharge fluid may have a lower GVF than that of the suction fluid
11, the separator may not be employed and at least a portion of the
discharge fluid may act as the motive fluid to pass through the
container 17 for delivery into the eductor 16.
[0023] In the illustrated example in FIG. 1, the recirculation
apparatus 15 is connected to one end of the discharge conduit 14,
so that all of the discharge fluid from the discharge conduit may
pass through the recirculation apparatus 15 for discharging and/or
processing, such as the gas and liquid separation. Alternatively,
only a portion of the discharge fluid may pass through the
recirculation apparatus 15. For example, the recirculation
apparatus 15 is disposed to bypass the discharge conduit 14 to
receive a portion of the discharge fluid. Thus, in certain
applications, the container 17 may not be employed.
[0024] The eductor 16 is assembled onto the suction conduit 13 and
is configured to receive and eject the motive fluid from the
recirculation apparatus 15 into the suction conduit 13 to improve
flow conditions of the suction fluid, for example reducing the GVF
of the multiphase fluid. In some applications, the eductor 16 may
be detachable disposed on or be unitary with the suction conduit
13.
[0025] FIG. 2 illustrates a schematic diagram of an arrangement of
the eductor 16 and the suction conduit 13 of the pump assembly 10
in accordance with one embodiment of the invention. As illustrated
in FIG. 2, the eductor 16 comprises a motive pipe 20 and a motive
nozzle 21 disposed at one end of the motive body 20. The motive
nozzle 21 has a taper shape and the suction conduit 13 has a
cylindrical shape. Alternatively, the motive nozzle 21 and the
suction conduit 13 may have other shapes, for example, the motive
nozzle 21 has a cylindrical shape.
[0026] For the arrangement illustrated in FIG. 2, the motive pipe
20 is in fluid communication with the recirculation apparatus 15
with the other end thereof via the connection conduit 18 (shown in
FIG. 1) for delivering the motive fluid from the recirculation
apparatus 15 into the motive nozzle 21. The motive nozzle 21 is
accommodated into and configured to reject the motive fluid into
the suction conduit 13 to mix with the multiphase fluid 11. In some
examples, the motive nozzle 21 may be detachably disposed on or be
unitary with the motive pipe 20.
[0027] In some applications, the motive nozzle 21 may introduce the
motive fluid into the suction conduit 13 and toward the centrifugal
pump 12 along a suction direction 23 or a flow direction roughly
co-directional with the flow of the multiphase fluid through the
suction conduit 13 toward the centrifugal pump 12, which may
indicate that, in some examples, the motive nozzle 21 may extend
along an axis (not shown) parallel to an axis of the suction
conduit 13, as depicted in FIG. 2. In other examples, as depicted
in FIG. 3, each of the two motive nozzles 21 extends along an axis
having an acute angle with the axis of the suction conduit 13 to
introduce the motive fluid into the suction conduit 13 and toward
the centrifugal pump 12 along a suction direction.
[0028] Thus, the motive fluid is introduced into the multiphase
fluid such that from initial contact of the multiphase fluid and
the motive fluid, both fluids move unidirectionally along a flow
path leading to the centrifugal pump. In some example, the motive
nozzle 21 may be coaxial with the suction conduit 13. In one
example, the suction direction indicates a substantially horizontal
flow direction.
[0029] It should be noted that the arrangements in FIGS. 2-3 are
merely illustrative. For the arrangement in FIG. 2, in some
applications, as illustrated in FIG. 4, more than one motive nozzle
21 may be disposed along the axis parallel to the axis of the
suction conduit 13 to introduce the motive fluid into the suction
conduit 13. For the arrangement in FIG. 3, in certain applications,
one or more than two motive nozzles 21 may be disposed along the
axis having an acute angle with the axis of the suction conduit 13
to introduce the motive fluid into the suction conduit 13. In
non-limiting examples, the pump assembly 10 may comprise the
arrangements of the motive nozzles shown both in FIGS. 2 and 3
simultaneously.
[0030] For some arrangements, the motive fluid may have a higher
total pressure and a lower GVF than those of the multiphase fluid
11. Thus, during the motive fluid is ejected into the suction
conduit 13 and mixes with the multiphase fluid 11, a static
pressure and a flow velocity of a mixture fluid, which may also act
as a suction fluid, of the motive fluid and the multiphase fluid 11
are increased. Meanwhile, the increased pressure of the multiphase
fluid and compressibility of the gaseous liquids therein result in
that the multiphase fluid may have a lower GVF for suction into the
centrifugal pump 12.
[0031] Accordingly, in non-limiting examples, the mixture fluid may
have a higher pressure and a lower GVF due to the higher pressure
of the motive fluid, so that the flow conditions of the mixture
fluid may be enhanced to ensure stable operation of the centrifugal
pump 12 without loss of prime even though the multiphase fluid 11
has a higher GVF before suction into the centrifugal pump 12.
[0032] FIG. 5 illustrated a schematic diagram of the arrangement of
the eductor 16 and the suction conduit 13 in accordance with
another embodiment of the invention. The arrangements in FIGS. 2
and 5 are similar, and the two arrangements differ in that the
motive nozzle 21 shown in FIG. 2 is disposed within the suction
conduit 13. The motive nozzle 21 shown in FIG. 5 not only extends
along the suction direction of the multiphase fluid, but also
extends into the centrifugal pump 12, for example, one end of the
motive nozzle 21 extends into the suction nozzle 24 of the
centrifugal pump 12.
[0033] Additionally, for the arrangement illustrated in FIG. 1, the
pump assembly 10 further comprises a detector 25 and a control
valve 26 connected to the detector 25. The detector 25 is disposed
between the eductor 16 and the centrifugal pump 12 for detecting
the GVF of the multiphase fluid in the suction conduit 13. The
control valve 26 is disposed between the eductor 16 and the
recirculation apparatus 15 to control the flow of the motive fluid
in the conduit 18. Non-limiting examples of the detector 25 include
a multiphase flow meter or other suitable detectors based on
pressures, temperatures and/or flow rates of the multiphase fluid
for detecting GVF thereof.
[0034] Thus, during operation, the centrifugal pump 12 is actuated,
for example using an electrical motor (not shown) to pump the
multiphase fluid 11 via the suction conduit 13. The detector 25
detects the GVF of the multiphase fluid 11 while the multiphase
fluid 11 enters into the centrifugal pump 12 and at least a portion
of the discharge fluid enters into the recirculation apparatus 15.
Then, when the GVF of the multiphase fluid 11 exceeds a threshold
value, the detector 25 triggers the control valve 26 to open the
conduit 18, so that the motive fluid is ejected into the suction
conduit 13 to mix with the multiphase fluid 11 via the eductor 16
so as to decrease the GVF of the mixture fluid (suction fluid) to
ensure stable operation of the centrifugal pump 12. Next, when the
GVF of the mixture fluid drops below the threshold value, the
detector 25 triggers the control valve 26 to close the conduit 18
and conserve the motive fluid in the recirculation apparatus
15.
[0035] In some examples, the detector 25 may not be employed. For
example, before delivery of the motive fluid into the suction
conduit 13, when the GVF of the multiphase fluid 11 exceeds the
threshold value, the centrifugal pump 12 may vibrate due to the
accumulation of the gaseous fluid and imbalance flow in the pump
12. Thus, one may turn on the control valve manually to make the
motive fluid enters into the eductor 16 via the conduit 25.
[0036] It should be noted that the arrangements in FIGS. 1-5 are
merely illustrative. For some arrangements, the recirculation
apparatus 15 may not be employed. As mentioned above, in some
examples, the discharge fluid may function as the motive fluid.
Thus, the eductor 16 may be directly in fluid communication with
the discharge conduit 14 and receive at least a portion of the
discharge fluid from the discharge conduit 14 for injection into
the suction conduit 13.
[0037] For other arrangements, a motive fluid source (not shown)
separated from the discharge conduit 14 may be provided to be in
fluid communication with and provide a motive fluid with a higher
pressure to the eductor 16. In certain applications, the motive
fluid from the separated fluid source may have a lower GVF than
that of the multiphase fluid 11. Alternatively, the motive fluid
may have the same GVF as or a higher GVF than that of the
multiphase fluid 11.
[0038] FIG. 6 shows example experimental data obtained using the
pump assembly 10 shown in FIG. 1. As illustrated in FIG. 6, with
regarding to respective GVF of the multiphase fluid 11, the pump
assembly 10 with the eductor has a higher discharge pressure than
that a pump assembly without the eductor, which indicates the
accumulation of the gaseous fluid and the flow imbalance of the
multiphase fluid is reduced in the pump assembly with the eductor,
so that the pump assembly with the eductor has a stable performance
and higher efficiency.
[0039] While the disclosure has been illustrated and described in
typical embodiments, it is not intended to be limited to the
details shown, since various modifications and substitutions can be
made without departing in any way from the spirit of the present
disclosure. As such, further modifications and equivalents of the
disclosure herein disclosed may occur to persons skilled in the art
using no more than routine experimentation, and all such
modifications and equivalents are believed to fall within the
spirit and scope of the disclosure as defined by the claims
presented herein.
* * * * *