U.S. patent application number 13/271698 was filed with the patent office on 2013-04-18 for system and method for controlling flow through a rotor.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. The applicant listed for this patent is Narendra Are, Hari Krishna Meka. Invention is credited to Narendra Are, Hari Krishna Meka.
Application Number | 20130094958 13/271698 |
Document ID | / |
Family ID | 47010369 |
Filed Date | 2013-04-18 |
United States Patent
Application |
20130094958 |
Kind Code |
A1 |
Meka; Hari Krishna ; et
al. |
April 18, 2013 |
SYSTEM AND METHOD FOR CONTROLLING FLOW THROUGH A ROTOR
Abstract
One embodiment of the present invention is a system for
controlling flow through a rotor. The system includes an inlet port
in the rotor and an outlet port in the rotor. The outlet port is in
fluid communication with the inlet port. A fixed orifice is
disposed in at least one of the inlet or outlet ports. A variable
orifice is disposed in at least one of the inlet or outlet ports in
a separate location from the fixed orifice.
Inventors: |
Meka; Hari Krishna;
(Bangalore, IN) ; Are; Narendra; (Greenville,
SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Meka; Hari Krishna
Are; Narendra |
Bangalore
Greenville |
SC |
IN
US |
|
|
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
47010369 |
Appl. No.: |
13/271698 |
Filed: |
October 12, 2011 |
Current U.S.
Class: |
416/1 ;
416/91 |
Current CPC
Class: |
F01D 19/02 20130101;
F01D 25/10 20130101; F01D 5/08 20130101 |
Class at
Publication: |
416/1 ;
416/91 |
International
Class: |
F01D 5/08 20060101
F01D005/08; F01D 5/02 20060101 F01D005/02 |
Claims
1. A system for controlling flow through a rotor comprising: a. an
inlet port in the rotor; b. an outlet port in the rotor, wherein
the outlet port is in fluid communication with the inlet port; c. a
fixed orifice disposed in at least one of the inlet or outlet
ports; and d. a variable orifice disposed in at least one of the
inlet or outlet ports at separate location from the fixed
orifice.
2. The system as in claim 1, further comprising a plurality of
passages in the rotor between the inlet port in the outlet
port.
3. The system as in claim 1, wherein the fixed orifice, variable
orifice, or combinations thereof comprises a valve.
4. The system as in claim 1, wherein the fixed orifice, variable
orifice, or combinations thereof, has a first position and a second
position, wherein the first position permits flow through at least
one of the inlet or outlet ports, and wherein the second position
prevents flow through at least one of the inlet or outlet
ports.
5. The system as in claim 1, further comprising a controller
connected to the fixed orifice, variable orifice, or combinations
thereof.
6. The system as in claim 5, wherein the controller generates a
signal to the fixed orifice, variable orifice, or combinations
thereof, wherein the signal is based on a temperature.
7. The system as in claim 5, wherein the controller generates a
signal to the fixed orifice, variable orifice, or combinations
thereof wherein the signal is based on a time.
8. A system for warming a rotor comprising: a. a fluid passage
through the rotor; b. a first valve disposed in the fluid passage
to control the flow of a fluid through the fluid passage; and c. a
second valve disposed in a different location of the fluid passage
from the first valve to control the flow of a fluid through the
fluid passage.
9. The system as in claim 8, wherein the first valve, second valve,
or combinations thereof, has a first position and a second
position, wherein the first position permits the fluid to flow
through the fluid passage, and wherein the second position prevents
the fluid from flowing through the passage.
10. The system as in claim 8, further comprising a controller
connected to the first valve, second valve, or combinations
thereof.
11. The system as in claim 10, wherein the controller generates a
signal to the first valve, second valve, or combinations thereof,
wherein the signal is based on a temperature.
12. The system as in claim 10, wherein the controller generates a
signal to the first valve, second valve, or combinations thereof,
wherein the signal is based on a time.
13. A method for controlling flow through a rotor comprising: a.
diverting a process fluid; b. flowing the diverted process fluid
through a fluid passage in the rotor, the fluid passage including a
first orifice and a second orifice that is separate from the first
orifice; and c. reducing the flow of the diverted process fluid
through the fluid passage in the rotor by using the first orifice,
second orifice, or combinations thereof.
14. The method as in claim 13, further comprising diverting the
process fluid from a compressor.
15. The method as in claim 13, further comprising reducing the flow
of the diverted process fluid through the fluid passage in the
rotor based on a predetermined temperature limit.
16. The method as in claim 13, further comprising reducing the flow
of the diverted process fluid through the fluid passage in the
rotor based on a predetermined time limit.
17. The method as in claim 13, wherein the first orifice, second
orifice, or combinations thereof comprises a valve.
18. The method as in claim 17, further comprising generating a
signal to the valve, wherein the signal is based on a
temperature.
19. The method as in claim 17, further comprising generating a
signal to the valve, wherein the signal is based on a time.
Description
FIELD OF THE INVENTION
[0001] The present invention generally involves a system and method
for controlling flow through a rotor. For example, particular
embodiments of the present invention may control the amount of
fluid diverted through a rotor to warm up the rotor.
BACKGROUND OF THE INVENTION
[0002] Gas turbines are widely used in industrial and commercial
operations. A typical gas turbine includes a compressor at the
front, one or more combustors around the middle, and a turbine at
the rear. The compressor imparts kinetic energy to the working
fluid (e.g., air) to produce a compressed working fluid at a highly
energized state. The compressed working fluid exits the compressor
and flows to the combustors where it mixes with fuel and ignites to
generate combustion gases having a high temperature and pressure.
The combustion gases flow to the turbine where they expand to
produce work. For example, expansion of the combustion gases in the
turbine may rotate a shaft connected to a generator to produce
electricity.
[0003] The compressor and the turbine typically share a common
rotor which extends from near the front of the compressor, through
the combustor section, to near the rear of the turbine. Due to the
length and size of the rotor, the total weight of the rotor may
approach or exceed 100 tons. During startup of the gas turbine, as
compressed working fluid flows through the compressor and
combustion gases flow through the turbine, the outer portion of the
rotor heats up faster than the inner portion of the rotor creating
a temperature gradient across the rotor profile. The temperature
gradient across the rotor profile produces substantial thermal
stresses across the rotor that are generally proportional to
T.sub.max-T.sub.ave. T.sub.max is the maximum temperature across
the rotor profile. In compressor section, T.sub.max may approach
the temperature of the compressed working fluid exiting the
compressor, and in the turbine section, T.sub.max may approach the
temperature of the combustion gases entering the turbine. T.sub.ave
is the average temperature across the rotor profile and is
initially ambient temperature during a cold startup of the gas
turbine. The thermal stress across the rotor continues until the
temperature across the rotor profile reaches equilibrium, which may
be 12 hours or longer, and substantially reduces the low cycle
fatigue limit of the rotor.
[0004] Various systems and methods are known in the art for
reducing the thermal stress across the rotor. For example, a
process fluid may be diverted from the compressor to flow through
the rotor to decrease the differential temperature between
T.sub.max and T.sub.aw and allow the rotor to reach equilibrium
temperature in a shorter period of time. However, the diverted
fluid decreases the efficiency of the compressor by reducing the
amount of compressed working fluid produced by the compressor. In
addition, the diverted fluid creates turbulence as it is
reintroduced into the compressor airflow, and the turbulence may
create laminar separation across the compressor blades. Therefore,
an improved system and method for controlling flow through a rotor
would be useful.
BRIEF DESCRIPTION OF THE INVENTION
[0005] Aspects and advantages of the invention are set forth below
in the following description, or may be obvious from the
description, or may be learned through practice of the
invention.
[0006] One embodiment of the present invention is a system for
controlling flow through a rotor. The system includes an inlet port
in the rotor and an outlet port in the rotor. The outlet port is in
fluid communication with the inlet port. A fixed orifice is
disposed in at least one of the inlet or outlet ports. A variable
orifice is disposed in at least one of the inlet or outlet ports in
a separate location from the fixed orifice.
[0007] Another embodiment of the present invention is a system for
warming a rotor. The system includes a fluid passage through the
rotor. A first valve is disposed in the fluid passage to control
the flow of a fluid through the fluid passage. A second valve is
disposed in a different location in the fluid passage from the
first valve to control the flow of a fluid through the fluid
passage.
[0008] The present invention may also include any method for
controlling flow through a rotor. The method includes diverting a
process fluid and flowing the diverted process fluid through a
fluid passage in the rotor, the fluid passage including a first
orifice and a second orifice that is separate from the first
orifice. The method further includes reducing the flow of be
diverted process fluid through the fluid passage in the rotor by
using the first orifice, second orifice, or combinations
thereof.
[0009] Those of ordinary skill in the art will better appreciate
the features and aspects of such embodiments, and others, upon
review of the specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] A full and enabling disclosure of the present invention,
including the best mode thereof to one skilled in the art, is set
forth more particularly in the remainder of the specification,
including reference to the accompanying figures, in which:
[0011] FIG. 1 is a simplified cross-section view of a rotor
according to one embodiment of the present invention;
[0012] FIG. 2 is a perspective view of one side of a rotor wheel
shown in FIG. 1 taken along line A-A; and
[0013] FIG. 3 is a perspective view of another side of a rotor
wheel shown in FIG. 1 taken along line B-B.
DETAILED DESCRIPTION OF THE INVENTION
[0014] Reference will now be made in detail to present embodiments
of the invention, one or more examples of which are illustrated in
the accompanying drawings. The detailed description uses numerical
and letter designations to refer to features in the drawings. Like
or similar designations in the drawings and description have been
used to refer to like or similar parts of the invention.
[0015] Each example is provided by way of explanation of the
invention, not limitation of the invention. In fact, it will be
apparent to those skilled in the art that modifications and
variations can be made in the present invention without departing
from the scope or spirit thereof. For instance, features
illustrated or described as part of one embodiment may be used on
another embodiment to yield a still further embodiment. Thus, it is
intended that the present invention covers such modifications and
variations as come within the scope of the appended claims and
their equivalents.
[0016] Embodiments within the scope of the present invention
provide a system and method for enhancing the expected life of a
rotor and improving the efficiency of a gas turbine. In various
embodiments, the present invention may control the flow of a fluid
through the rotor to warm the rotor, thereby reducing thermal
stresses across the rotor profile. The reduced thermal stresses
will enhance the low cycle fatigue limits of the rotor. In
addition, embodiments within the scope of the present invention
enhance the gas turbine efficiency by controlling the amount and/or
duration of fluid flow through the rotor. In this regard, it has
been determined that dual metering can be utilized to provide a
fixed metering area which controls fluid flow until a full load
condition when a second, separate active metering area can be
utilized to reduce flow.
[0017] FIG. 1 provides a simplified cross-section view of the top
half of a rotor 10 according to one embodiment of the present
invention. As shown, the rotor 10 may comprise a plurality of rotor
wheels 12 axially connected by a tie rod 14 to rotate together
around a centerline 16. In the compressor section, each rotor wheel
12 may be associated with a rotating blade 18 or stationary nozzle
20, as shown in FIG. 1. Similarly, in the turbine section, each
rotor wheel 12 may be associated with a rotating bucket or
stator.
[0018] As shown in FIG. 1, the rotor 10 includes a plurality of
cavities 22 between and through adjacent rotor wheels 12. The
cavities 22 reduce the total weight of the rotor 10. In addition,
the cavities 22 provide one or more fluid passages between and
around adjacent rotor wheels 12. The fluid passages include at
least one inlet port 24 and at least one outlet port 26 in fluid
communication with the inlet port 24. The inlet and/or outlet ports
24, 26 may comprise any suitable passage, plenum, or pathway
through a single rotor wheel 12 or between adjacent rotor wheels
12. For example, as shown in FIG. 2, the inlet port 24 or outlet
port 26 may comprise a radial bore hole between adjacent rotor
wheels 12. In this manner, a fluid may flow through the inlet port
24 into the fluid passage and through and/or around the rotor
wheels 12 before exiting the fluid passage through the outlet port
26, as indicated by the flow arrows in FIG. 1.
[0019] A variable orifice 28 may be disposed in the fluid passage
in at least one of the inlet or outlet ports 24, 26 to control the
fluid flow through the fluid passage. For example, the variable
orifice 28 may have a first position that permits fluid flow
through at least one of the inlet or outlet ports 24, 26 and a
second position that reduces and/or prevents fluid flow through at
least one of the inlet or outlet ports 24, 26. The variable orifice
28 may comprise any suitable mechanism known to one of ordinary
skill in the art for preventing or preventing fluid flow. For
example, as shown in FIG. 3, the variable orifice 28 may comprise a
thermally actuated valve 30 that responds to temperature changes in
the rotor wheels 12. As shown in FIG. 3, the valve 30 may include a
piston 32 or disk connected to a diaphragm 34 inside the valve 30.
At lower temperatures, the diaphragm 34 may contract to retract the
piston 32 or disc into the valve 30 to place the variable orifice
28 in the first position that allows or permits fluid flow through
at least one of the inlet or outlet ports 24, 26. As the rotor
wheel 12, and thus the rotor 10, increases temperature, the
diaphragm 34 may expand to force the piston 32 or disk out of the
valve 30 to obstruct or completely seal off the associated inlet or
outlet port 24, 26. With the piston 32 or disk extended into the
associated inlet or outlet port 24, 26, the variable orifice 28 is
in the second position which reduces or prevents fluid flow through
at least one of the inlet or outlet ports 24, 26.
[0020] A fixed orifice 40, which is separate from the variable
orifice 28, may also be disposed in the fluid passage in at least
one of the inlet or outlet ports 24, 26 to control the fluid flow
through the fluid passage. For example, the fixed orifice 40 may
have a first position that permits fluid flow through at least one
of the inlet or outlet ports 24, 26 and a second position that
reduces and/or prevents fluid flow through at least one of the
inlet or outlet ports 24, 26. The fixed orifice 40 can initially
control fluid flow until a full load condition. In this manner,
fixed orifice 40 in conjunction with variable orifice 28 can more
reliably control purge flows. Similar to the variable orifice 28,
fixed orifice 40 can comprise any suitable mechanism known to one
of ordinary skill in the art for preventing or preventing fluid
flow.
[0021] As shown in FIG. 1, the variable orifice 28 and fixed
orifice 40 may be connected to a controller 36 for remote operation
of the variable orifice 28 in alternate embodiments within the
scope of the present invention. Although not illustrated, variable
orifice 28 and fixed orifice 40 can be controlled by separate
controllers as well as would be understood by one of ordinary skill
in the art. As described herein, the technical effect of the
controller 36 is to transmit a signal 38 to the variable orifice 28
and/or fixed orifice 40 to remotely operate such orifice(s). The
controller 36 may be a stand alone component, such as a temperature
sensor or timer, or a sub-component included in any computer system
known in the art, such as a laptop, a personal computer, a mini
computer, or a mainframe computer. The various controller and
computer systems discussed herein are not limited to any particular
hardware architecture or configuration. Embodiments of the systems
and methods set forth herein may be implemented by one or more
general-purpose or customized controllers adapted in any suitable
manner to provide the desired functionality. For example, the
controller 36 may be adapted to provide additional functionality,
either complementary or unrelated to the present subject matter.
When software is used, any suitable programming, scripting, or
other type of language or combinations of languages may be used to
implement the teachings contained herein. However, some systems and
methods set forth and disclosed herein may also be implemented by
hard-wired logic or other circuitry, including, but not limited to,
application-specific circuits. Of course, various combinations of
computer-executed software and hard-wired logic or other circuitry
may be suitable as well.
[0022] The signal 38 generated by the controller 36 may be based on
any of several parameters being monitored that are reflective of
the rotor 10 temperature, thermal gradient across the rotor
profile, and/or thermal stresses across the rotor 10. For example,
the signal 38 may reflect or be based on a temperature of the rotor
10 that indicates that the temperature profile across the rotor 10
has reached equilibrium. Similarly, the signal 38 may reflect or be
based on the temperature of the compressed working fluid exiting
the compressor or the combustion gases flowing through the turbine
that indicates the maximum outer temperature of the rotor 10. As
another example, the signal 38 may reflect or be based on a time
interval determined through calculations or testing to be a
sufficient time for the rotor 10 to reach equilibrium.
[0023] During operation, the fixed orifice 40 may be in the first
or open position during start up of the gas turbine to divert a
portion of a process fluid, such as the working fluid flowing
through the compressor, through the inlet port 24. The diverted
fluid would then flow through the fluid passages in the rotor 10,
exiting through the outlet port 26 and returning to the flow of
compressed working fluid through the compressor or the combustion
gases in the turbine. As the diverted fluid heats up the rotor 10,
the variable orifice 28 will eventually close. For example, if
thermally actuated, the increased temperature will cause the
variable orifice 28 to reposition to the second or closed position
to reduce or prevent the fluid flow through the fluid passages.
Alternately, or in addition, the controller 36 may generate the
signal 38 to the variable orifice 28 to reposition the variable
orifice 28 between the first or second positions, as desired. In
this manner, utilizing the dual metering of the present disclosure
allows for the fixed orifice 40 to control fluid flow until a full
load condition and the variable orifice 28, which is located at a
separate location, to reduce the
[0024] The systems described and illustrated with respect to FIGS.
1-3 may also provide a method for controlling flow through the
rotor 10. The method may include diverting a process fluid, for
example compressed working fluid from the compressor, and flowing
the diverted process fluid through fluid passages in the rotor 10,
such fluid passage including first and second orifices that are
separate from one another. The method may further include reducing
the flow of the diverted process fluid through the fluid passages
in the rotor 10 using the first orifice and/or the second orifice,
for example based on a predetermined temperature limit or a
predetermined time limit. In particular embodiments, the variable
orifice 28 or valve may be used to reduce the flow of the diverted
process fluid through the passage in the rotor 10, and the
controller 36 may generate the signal 38 based on a temperature or
time.
[0025] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to practice the invention, including making and
using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other and examples are intended to be within the
scope of the claims if they include structural elements that do not
differ from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal languages of the claims.
* * * * *