U.S. patent application number 13/934599 was filed with the patent office on 2015-01-08 for system for determining target misalignment in turbine shaft and related method.
The applicant listed for this patent is General Electric Company. Invention is credited to Lawrence Brown Farr, II, Andrea Booher Kretschmar, Peter Ping-Liang Sue.
Application Number | 20150010386 13/934599 |
Document ID | / |
Family ID | 52015151 |
Filed Date | 2015-01-08 |
United States Patent
Application |
20150010386 |
Kind Code |
A1 |
Sue; Peter Ping-Liang ; et
al. |
January 8, 2015 |
SYSTEM FOR DETERMINING TARGET MISALIGNMENT IN TURBINE SHAFT AND
RELATED METHOD
Abstract
Systems and devices configured to determine misalignment of
targets of a rotating shaft by monitoring axial and radial aspects
of targets and the shaft. In one embodiment, a target monitoring
system includes a first horizontal probe communicatively connected
to at least one first horizontal target connected to the shaft, and
a first axial probe located adjacent to the first horizontal probe
and communicatively connected to the first horizontal target. The
system also includes a second horizontal probe communicatively
connected to at least one second horizontal target connected to the
shaft, and a second axial probe located adjacent to the second
horizontal probe and communicatively connected to the second
horizontal target. The system may further include an end probe
disposed proximate a first end of the shaft for monitoring axial
movement of the shaft, and a computing device communicatively
connected to the end probe and each horizontal and axial probe.
Inventors: |
Sue; Peter Ping-Liang;
(Greenville, SC) ; Farr, II; Lawrence Brown;
(Greenville, SC) ; Kretschmar; Andrea Booher;
(Simpsonville, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Family ID: |
52015151 |
Appl. No.: |
13/934599 |
Filed: |
July 3, 2013 |
Current U.S.
Class: |
415/118 ;
73/112.01 |
Current CPC
Class: |
Y02E 20/16 20130101;
F01D 21/045 20130101; G01B 11/272 20130101; G01B 21/24 20130101;
F01D 21/003 20130101; G01M 15/14 20130101 |
Class at
Publication: |
415/118 ;
73/112.01 |
International
Class: |
G01M 15/14 20060101
G01M015/14; F01D 21/00 20060101 F01D021/00; G01B 5/14 20060101
G01B005/14 |
Claims
1. A target monitoring system comprising: a first horizontal probe
located radially outboard of a shaft and communicatively connected
to at least one first horizontal target connected to the shaft, the
at least one first horizontal target disposed proximate a first end
of the shaft; a first axial probe located axially adjacent to the
first horizontal probe and communicatively connected to the at
least one first horizontal target; a second horizontal probe
located radially outboard of the shaft communicatively connected to
at least one second horizontal target connected to the shaft, the
at least one second horizontal target disposed proximate a second
end of the shaft; a second axial probe located axially adjacent to
the second horizontal probe and communicatively connected to the at
least one second horizontal target; an end probe disposed proximate
the first end of the shaft, the end probe configured to monitor
axial movement of the shaft; and a computing device communicatively
connected to the end probe and each of the first horizontal probe,
the first axial probe, the second horizontal probe and the second
axial probe, wherein the computing device is configured to:
determine a first gradient for the at least one first horizontal
target based on a displacement between the first horizontal probe
and the at least one first horizontal target and the first axial
probe and the at least one first horizontal target; and determine a
second gradient for the at least one second horizontal target based
on a displacement between the second horizontal probe and the at
least one second horizontal target and the second axial probe and
the at least one second horizontal target.
2. The target monitoring system of claim 1, wherein the end probe
includes at least one of: a Bentley Nevada probe, a clearance probe
and a magnetic pick-up probe.
3. The target monitoring system of claim 1, wherein at least one of
the first horizontal probe, the first axial probe, the second
horizontal probe, and the second axial probe include an optical
probe.
4. The target monitoring system of claim 1, wherein the first
horizontal probe and the first axial probe are located a
predetermined distance apart in the axial direction relative to the
shaft.
5. The target monitoring system of claim 1, wherein the computing
device is configured to determine misalignment between the at least
one first horizontal target and the at least one second horizontal
target based on the axial movement of the shaft and the first
gradient and the second gradient of the at least one first
horizontal target and the at least one second horizontal
target.
6. The target monitoring system of claim 1, further comprising a
plurality of targets disposed circumferentially about the shaft and
communicatively connected to at least one of: the first horizontal
probe, the first axial probe, the second horizontal probe, and the
second axial probe.
7. The target monitoring system of claim 6, further comprising a
plurality of probes communicatively connected to the plurality of
targets and the computing device, the computing device further
configured to monitor the plurality of targets during rotation of
the shaft via the plurality of probes, wherein the computing device
is configured to determine torsional displacement of the shaft
based on the monitoring of the plurality of targets, and wherein
the computing device is configured to factor axial movement of the
shaft in the torsional displacement determination.
8. A method comprising: determining a first primary displacement
between a first horizontal probe and at least one first target on a
shaft, the at least one first target located proximate a first end
of the shaft; determining a second primary displacement between a
first axial probe and the at least one first target; calculating a
first gradient of the at least one first target based on the first
primary displacement and the second primary displacement;
monitoring axial movement of the shaft via an end probe; and
determining an amount of false twisting of the shaft at load
condition based on: a difference between the first gradient and a
calculated second gradient; and the axial movement of the
shaft.
9. The method of claim 8, further comprising: determining a first
secondary displacement between a second horizontal probe and at
least one second target on the shaft, the at least one second
target located proximate a second end of the shaft; determining a
second secondary displacement between a second axial probe and the
at least one second target; and calculating the second gradient of
the second target based on the first secondary displacement and the
second secondary displacement.
10. The method of claim 8, wherein the shaft is at a no load
condition during the determining of the first displacement and the
determining of the second displacement.
11. The method of claim 8, wherein the shaft is at a load condition
during the monitoring of the axial movement.
12. The method of claim 8, wherein the end probe includes at least
one of: a Bentley Nevada probe, a clearance probe and a magnetic
pick-up probe.
13. The method of claim 8, wherein the first horizontal probe and
the first axial probe are located a predetermined distance apart in
the axial direction relative to the shaft.
14. The method of claim 8, wherein at least one of the first
horizontal probe, the first axial probe, the second horizontal
probe, and the second axial probe include an optical probe.
15. The method of claim 8, further comprising: monitoring via a
computing device a plurality of probes communicatively connected to
a plurality of targets disposed on the shaft, the computing device
configured to monitor the plurality of targets during rotation of
the shaft via the plurality of probes, wherein the computing device
is configured to determine torsional displacement of the shaft
based on the monitoring of the plurality of targets, and wherein
the computing device is configured to factor axial movement of the
shaft in the torsional displacement determination.
16. A turbine comprising: a stator; a working fluid passage
substantially surrounded by the stator; and a shaft configured
radially inboard of the stator and in the working fluid passage;
and a target monitoring system communicatively connected to the
shaft and configured to monitor displacement of the shaft during
operation of the turbine, the target monitoring system including: a
first horizontal probe located radially outboard of the shaft and
communicatively connected to at least one first horizontal target
connected to the shaft, the at least one first horizontal target
disposed proximate a first end of the shaft; a first axial probe
located axially adjacent to the first horizontal probe and
communicatively connected to the at least one first horizontal
target; a second horizontal probe located radially outboard of the
shaft communicatively connected to at least one second horizontal
target connected to the shaft, the at least one second horizontal
target disposed proximate a second end of the shaft; a second axial
probe located axially adjacent to the second horizontal probe and
communicatively connected to the at least one second horizontal
target; an end probe disposed proximate the first end of the shaft,
the end probe configured to monitor axial movement of the shaft;
and a computing device communicatively connected to the end probe
and each of the first horizontal probe, the first axial probe, the
second horizontal probe and the second axial probe, wherein the
computing device is configured to: determine a first gradient for
the at least one first horizontal target based on a displacement
between the first horizontal probe and the at least one first
horizontal target and the first axial probe and the at least one
first horizontal target; and determine a second gradient for the at
least one second horizontal target based on a displacement between
the second horizontal probe and the at least one second horizontal
target and the second axial probe and the at least one second
horizontal target.
17. The turbine of claim 16, wherein the end probe includes at
least one of: a Bentley Nevada probe, a clearance probe and a
magnetic pick-up probe.
18. The turbine of claim 16, wherein at least one of the first
horizontal probe, the first axial probe, the second horizontal
probe, and the second axial probe include an optical probe.
19. The turbine of claim 16, wherein the first horizontal probe and
the first axial probe are located a predetermined distance apart in
the axial direction relative to the shaft.
20. The turbine of claim 16, wherein the computing device is
configured to determine misalignment between the at least one first
horizontal target and the at least one second horizontal target
based on the axial movement of the shaft and the first gradient and
the second gradient of the at least one first horizontal target and
the at least one second horizontal target.
Description
BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein relates to a system for
determining torsional displacement of a rotating shaft, and, more
specifically, to a system and method for determining movement of a
power generation system shaft and/or targets during operation.
[0002] Some power plant systems, for example certain nuclear,
simple cycle, and combined cycle power plant systems, employ
turbines in their design and operation. Some of these turbines
include shafts which during operation are rotated at high speeds to
transfer torque about the turbine and power generation system
(e.g., from prime drivers to generators). These shafts may have
long axial dimensions relative to respective thicknesses/radial
dimensions of the shaft. As a result of these long axial dimensions
and the magnitude of the torque transferred, these shafts may
experience torsional displacement which may cause a first end of
any given shaft to be displaced/twisted, and/or radially shifted
relative to a second end of the shaft during operation. In some
power generation systems the power output of turbines may be
determined by monitoring a set of targets disposed
circumferentially about the shaft, the displacement of these
targets relative to one another providing a measurement of the
twist imposed on the shaft due to torque on the shaft. When errors
caused by radial movement are eliminated, the angle of twist on the
shaft can be determined and related to a calibration. As a result,
known, controlled and measured forces are applied to the shaft, and
a highly accurate measure of the associated power output of the
turbine may be delivered. Employment of a method that includes
disposing a plurality of sensors at each end about the shaft in
communication with a set of a plurality of targets disposed about
each end of the shaft allows determination of the aforementioned
error in measurement due to radial motion of the shaft. However,
these systems may not be able to monitor axial shaft movement
and/or may not be able to determine the effects of the shaft
movement on the accuracy of torque measurements. Additionally, if
the targets are not parallel to a centerline of the shaft, the
measurement may introduce another error into the measured angle of
twist of the shaft which may limit process accuracy and thus reduce
the accuracy of the torque and power output determinations.
BRIEF DESCRIPTION OF THE INVENTION
[0003] Systems and devices configured to monitor displacement of a
rotating shaft by monitoring axial and radial targets are
disclosed.
[0004] A first aspect of the invention includes a target monitoring
system having: a first horizontal probe located radially outboard
of a shaft and communicatively connected to at least one first
horizontal target connected to the shaft, the at least one first
horizontal target disposed proximate a first end of the shaft; a
first axial probe located axially adjacent to the first horizontal
probe and communicatively connected to the at least one first
horizontal target; a second horizontal probe located radially
outboard of the shaft communicatively connected to at least one
second horizontal target connected to the shaft, the at least one
second horizontal target disposed proximate a second end of the
shaft; a second axial probe located axially adjacent to the second
horizontal probe and communicatively connected to the at least one
second horizontal target; an end probe disposed proximate the first
end of the shaft, the end probe configured to monitor axial
movement of the shaft; and a computing device communicatively
connected to the end probe and each of the first horizontal probe,
the first axial probe, the second horizontal probe, and the second
axial probe, wherein the computing device configured to: determine
a first gradient for the at least one first horizontal target based
on a displacement between the first horizontal probe and the at
least one first horizontal target and the first axial probe and the
at least one first horizontal target; and determine a second
gradient for the at least one second horizontal target based on a
displacement between the second horizontal probe and the at least
one second horizontal target and the second axial probe and the at
least one second horizontal target.
[0005] A second aspect of the invention includes a method
including: determining a first primary displacement between a first
horizontal probe and at least one first target on a shaft, the at
least one first target located proximate a first end of the shaft;
determining a second primary displacement between a first axial
probe and the at least one first target; calculating a first
gradient of the at least one first target based on the first
primary displacement and the second primary displacement;
monitoring axial movement of the shaft via an end probe; and
determining an amount of false twisting of the shaft at load
condition based on: a difference between the first gradient and a
calculated second gradient; and the axial movement of the
shaft.
[0006] A third aspect of the invention includes a turbine having: a
stator; a working fluid passage substantially surrounded by the
stator; and a shaft configured radially inboard of the stator and
in the working fluid passage; and a target monitoring system
communicatively connected to the shaft and configured to monitor
displacement of the shaft during operation of the turbine, the
target monitoring system including: a first horizontal probe
located radially outboard of the shaft and communicatively
connected to at least one first horizontal target connected to the
shaft, the at least one first horizontal target disposed proximate
a first end of the shaft; a first axial probe located axially
adjacent to the first horizontal probe and communicatively
connected to the at least one first horizontal target; a second
horizontal probe located radially outboard of the shaft
communicatively connected to at least one second horizontal target
connected to the shaft, the at least one second horizontal target
disposed proximate a second end of the shaft; a second axial probe
located axially adjacent to the second horizontal probe and
communicatively connected to the at least one second horizontal
target; an end probe disposed proximate the first end of the shaft,
the end probe configured to monitor axial movement of the shaft;
and a computing device communicatively connected to the end probe
and each of the first horizontal probe, the first axial probe, the
second horizontal probe, and the second axial probe, wherein the
computing device configured to: determine a first gradient for the
at least one first horizontal target based on a displacement
between the first horizontal probe and the at least one first
horizontal target and the first axial probe and the at least one
first horizontal target; and determine a second gradient for the at
least one second horizontal target based on a displacement between
the second horizontal probe and the at least one second horizontal
target and the second axial probe and the at least one second
horizontal target.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] These and other features of this invention will be more
readily understood from the following detailed description of the
various aspects of the invention taken in conjunction with the
accompanying drawings that depict various embodiments of the
invention, in which:
[0008] FIG. 1 shows a three-dimensional partial cut-away
perspective view of a portion of a turbine according to an
embodiment of the invention;
[0009] FIG. 2 shows a cross-sectional view of a rotating shaft in a
simple cycle power generation system in accordance with embodiments
of the invention;
[0010] FIG. 3 shows a cross-sectional view of a rotating shaft in a
combined cycle power generation system in accordance with
embodiments of the invention;
[0011] FIG. 4 shows a perspective view of the combined cycle power
generation system of FIG. 2 in accordance with embodiments of the
invention;
[0012] FIG. 5 shows a cross-sectional view of a rotating shaft
taken along view line 7-7 of FIG. 2 or 3 according to an embodiment
of the invention;
[0013] FIG. 6 shows a cross-sectional view of a rotating shaft
taken along view line 7-7 of FIG. 2 or 3 including a graphical
representation of target displacement by shaft movement according
to embodiments of the invention;
[0014] FIG. 7 shows a schematic view of a target monitoring system
in accordance with embodiments of the invention;
[0015] FIG. 8 shows a schematic illustration of an environment
including a control system in accordance with an embodiment of the
invention;
[0016] FIG. 9 shows a schematic block diagram illustrating portions
of a combined cycle power plant system according to embodiments of
the invention; and
[0017] FIG. 10 shows a schematic block diagram illustrating
portions of a single-shaft combined cycle power plant system
according to embodiments of the invention.
[0018] It is noted that the drawings of the invention are not
necessarily to scale. The drawings are intended to depict only
typical aspects of the invention, and therefore should not be
considered as limiting the scope of the invention. It is understood
that elements similarly numbered between the FIGURES may be
substantially similar as described with reference to one another.
Further, in embodiments shown and described with reference to FIGS.
1-10, like numbering may represent like elements. Redundant
explanation of these elements has been omitted for clarity.
Finally, it is understood that the components of FIGS. 1-10 and
their accompanying descriptions may be applied to any embodiment
described herein.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Aspects of the invention provide for a target monitoring
system which includes an end probe (e.g., a Bentley Nevada probe,
clearance probe, a proximity probe, a magnetic pick-up sensor,
etc.) configured to determine axial movement of a rotating shaft
and a set of axial probes configured to determine the gradient of
misalignment for each target by monitoring changes in the
displacement of each target disposed on the shaft.
[0020] In contrast to conventional approaches, aspects of the
invention include an end probe and a set of axial probes which are
disposed proximate sets of horizontal and vertical probes and
configured to monitor a set of targets on the shaft. During
operation the target monitoring system monitors the displacement of
the set of targets relative to at least one of an axial probe and a
horizontal and/or vertical probe to determine a gradient of
misalignment for each target. An end probe monitors axial movement
of the shaft itself during operation, and the system is able to
determine the amount of false twisting of the rotating shaft by
considering the product of the gradient and the axial movement, and
incorporating this false twisting into the torque and/or power
output calculation for correction.
[0021] As used herein, the terms "axial" and/or "axially" refer to
the relative position/direction of objects along axis A, which is
substantially parallel to the axis of rotation of the turbomachine
(in particular, the rotor section). As further used herein, the
terms "radial" and/or "radially" refer to the relative
position/direction of objects along axis (r), which is
substantially perpendicular with axis A and intersects axis A at
only one location. Additionally, the terms "circumferential" and/or
"circumferentially" refer to the relative position/direction of
objects along a circumference which surrounds axis A but does not
intersect the axis A at any location.
[0022] Turning to the FIGURES, embodiments of systems and devices
are shown, which are configured to determine torsional displacement
of a rotating shaft including axial displacements of the shaft
during operation by monitoring a set of targets disposed about the
shaft with a set of probes. Each of the components in the FIGURES
may be connected via conventional means, e.g., via a common conduit
or other known means as is indicated in FIGS. 1-10. Referring to
the drawings, FIG. 1 shows a perspective partial cut-away
illustration of a gas or steam turbine 2. Turbine 2 includes a
rotor 4 that includes a rotating shaft 20 and a plurality of
axially spaced rotor wheels 8. A plurality of rotating blades 80
are mechanically coupled to each rotor wheel 8. More specifically,
blades 80 are arranged in rows that extend circumferentially around
each rotor wheel 8. A plurality of stationary vanes 82 extend
circumferentially around shaft 20, and the vanes are axially
positioned between adjacent rows of blades 80. Stationary vanes 82
cooperate with blades 80 to form a stage and to define a portion of
a flow path through turbine 2.
[0023] In operation, gas 84 enters an inlet 86 of turbine 2 and is
channeled through stationary vanes 82. Vanes 82 direct gas 84
against blades 80. Gas 84 passes through the remaining stages
imparting a force on blades 80 causing shaft 20 to rotate. At least
one end of turbine 2 may extend axially away from rotating shaft 20
and may be attached to a load or machinery (not shown) such as, but
not limited to, a generator, and/or another turbine.
[0024] In one embodiment, turbine 2 may include five stages. The
five stages are referred to as L0, L1, L2, L3 and L4. Stage L4 is
the first stage and is the smallest (in a radial direction) of the
five stages. Stage L3 is the second stage and is the next stage in
an axial direction. Stage L2 is the third stage and is shown in the
middle of the five stages. Stage L1 is the fourth and next-to-last
stage. Stage L0 is the last stage and is the largest (in a radial
direction). It is to be understood that five stages are shown as
one example only, and each turbine may have more or less than five
stages. Also, as will be described herein, the teachings of the
invention do not require a multiple stage turbine.
[0025] Turning to FIG. 2, a cross-sectional view of a portion of a
target monitoring system 200 connected to a shaft 20 while a torque
27 is acting on shaft 20 that serves as a load coupling shaft is
shown according to embodiments of the invention. Target monitoring
system 200 includes a first axial probe 212 located proximate a
first horizontal probe 12, a second axial probe 214 located
proximate a second horizontal probe 14, and an end probe 211
located at an axial end of shaft 20. In an embodiment, first axial
probe 212 may be axially adjacent first horizontal probe 12 and
second axial probe 214 may be axially adjacent second horizontal
probe 14. In one embodiment, first axial probe 212 may be located
about 1 inch axially distant from first horizontal probe 12 and
second axial probe 214 may be located about 1 inch axially distant
from first horizontal probe 14.
[0026] Shaft 20 is connected at a first end 24a to shaft 42 of gas
turbine 40 and connected at a second end 24b to a rotatable shaft
62 of power generator 60. Accordingly, shaft 20 forms a portion of
a simple cycle configuration of a power generation system in the
exemplary embodiment illustrated in FIG. 2. Shaft 20 may be rotated
by gas turbine machine 40 and may transmit that rotation to
rotatable shaft 62 of power generator 60. Rotatable shaft 62 of
power generator 60 may be connected to a magnet 64 which may rotate
with rotatable shaft 62 (and hence with shaft 20) within a stator
(not shown) of power generator 60 to generate electric power. In an
embodiment, shaft 20 may include a hollow area 22 and one or more
passageways 26 leading to hollow area 22. A set of wires 38 may
extend through passageways 26 and hollow area 22 to carry signals
to and/or from a RF telemetry system 36. RF telemetry system 36 may
be capable of rotating along with shaft 20 and transmits/receives
signals to/from, for example, power generator 60 through set of
wires 38 or wirelessly through a transmitting antenna of RF
telemetry system 36. Target monitoring system 200 may include a
pair of targets 32 and 34 which may be bonded on an outer surface
of shaft 20 and mounted on opposite axial ends of shaft 20 at a
distance `G` relative to one another.
[0027] In an embodiment, targets 32 and 34 may be separated along
the axial direction by about 80 inches, and a respective radii of
the outer surface on which targets 32 and 34 may be bonded may be
about 11 and about 22 inches, respectively. While FIG. 2 shows
targets 32 and 34 being bonded on the outer surface of shaft 20 at
different radii relative to one another, targets 32 and 34 may
alternatively be mounted on an outer surface of shaft 20 at the
same radii. In one embodiment, at least one of targets 32 and 34
may be formed by a pair of highly reflective tapes which are each
capable of intensifying and reflecting a light signal which is
incident on the tape. Each of targets 32 and 34 may be aligned at
the same circumferential position or be circumferentially offset
from one another. Additionally, it is understood that shaft 20 may
include two sets of targets 32, 34, wherein each set of targets 32,
34 includes at least one target 32, 34. That is, targets 32,34 may
each include a plurality of targets disposed circumferentially
around shaft 20, such that the respective probes (e.g., first axial
probe 212, second axial probe 214, first horizontal probe 12,
second horizontal probe 14) of target monitoring system 200 may
obtain data relating to targets 32 and 34, as discussed herein.
[0028] First axial probe 212, second axial probe 214, first
horizontal probe 12 and second horizontal probe 14 are positioned
at a perpendicular angle relative to the long axis of shaft 20.
First axial probe 212, second axial probe 214, first horizontal
probe 12 and second horizontal probe 14 may be aligned in the same
axial planes as targets 32 and 34, respectively. However, it may be
understood that first axial probe 212, second axial probe 214,
first horizontal probe 12 and second horizontal probe 14 may not be
aligned in the same axial planes as targets 32 and 34,
respectively, as long as first axial probe 212, second axial probe
214, first horizontal probe 12 and second horizontal probe 14
remain in substantially the same axial and radial position relative
to one another throughout the determining process discussed herein.
That is, probe 212 and probe 12 may be positioned in the same
circumferential position with respect to shaft 20, and probe 214
and probe 14 may be positioned in the same circumferential position
with respect to shaft 20. Additionally, the circumferential
position of probe 212 and probe 12 may or may not be in alignment
with the circumferential position of probe 214 and probe 14. In one
embodiment, first axial probe 212, second axial probe 214, first
horizontal probe 12 and second horizontal probe 14 may consist of
fiber optic elements for transmitting and receiving laser light
signals.
[0029] During operation, first horizontal probe 12 and second
horizontal probe 14 may monitor targets 32 and 34 to determine
torsional displacement of the shaft as discussed herein. First
axial probe 212, second axial probe 214, and end probe 211 may
monitor shaft 20, and targets 32 and 34 to determine axial
displacement (e.g., movement) of shaft 20 and target 32, 34
misalignments. At no load condition first horizontal probe 12 and
first axial probe 212 may measure a displacement of target 32
between each probe 12 and 212, the ratio of this displacement to
the axial distance between probe 12 and probe 212 representing the
first gradient for misalignment of target 32. Similarly, at no load
condition second horizontal probe 14 and second axial probe 214 may
measure a displacement of target 34 between each probe 14 and 214,
the ratio of this displacement to the axial distance between probe
14 and probe 214 representing the second gradient for misalignment
of target 34. End probe 211 may measure axial movement of shaft 20
at load condition. During operation, a product of the gradient and
the axial movement for each target represents an amount of false
twisting for that target which may be factored into torque and/or
power output determinations for increased accuracy.
[0030] In an exemplary embodiment according to the present
invention, a third horizontal probe 12a and a fourth horizontal
probe 14a may be employed, and positioned in a circular arc around
and perpendicular to the long axis of shaft 20 at about 180 degrees
from the positions of first horizontal probe 12 and second
horizontal probe 14, respectively. Similarly, as shown in FIG. 2,
first vertical probe 15 and second vertical probe 17 may be
positioned in a circular arc around the shaft 20 at about 180
degrees separation from third vertical probe 15a and fourth
vertical probe 17a, respectively. In one embodiment, as shown in
FIG. 2, first horizontal probe 12, third horizontal probe 12a,
second horizontal probe 14 and fourth horizontal probe 14a are
positioned with 90 degrees of separation relative to one another in
the same circular axial planes as the first vertical probes 15,
third vertical probe 15a, second vertical probe 17, and fourth
vertical probe 17a, respectively.
[0031] Probes 12, 12a, 14, 14a, 15, 15a, 17, 17a, 211, 212, and
214, may include laser light probes and may each be connected to a
processor 10. More specifically, probes 12, 12a, 14, 14a, 15, 15a,
17, 17a, 211, 212, and 214 may include at least one of a Bentley
Nevada probe, a clearance probe and/or a magnetic pick-up probe.
Processor 10, as will be discussed in more detail below, is capable
of calculating a torsional displacement (e.g., a circumferential
twist) of rotating shaft 20 based upon measurements taken by probes
12, 12a, 14, 14a, 15, 15a, 17, 17a, 211, 212, and 214, and
calculating a torque imposed on shaft 20 based on its torsional
displacement. Processor 10 may include, for example, General
Electric Aircraft Engine (GEAE) digital light probe system.
[0032] In an embodiment, target monitoring system 200 may include a
revolutional target 33 which may be bonded to an outer surface of
shaft 20 and may include a metal. In one embodiment, similar to
targets 32 and 34, revolutional target 33 may rotate along with
shaft 20. Revolutional target 33 may rotate proximate a
revolutional probe 13 once per revolution of shaft 20. In an
embodiment, revolutional probe 13 may be, for example, an eddy
current probe which detects the presence of (metal) revolutional
target 33. A signal from revolutional probe 13 may be triggered and
sent to processor 10 once during every revolution of shaft 20 as
revolutional target 33 passes by and is detected by revolutional
probe 13. The trigger signal provided from revolutional probe 13
enables processor 10 to establish a reference zero timing for
signals received by probe 12 and revolutional probe 13 for every
revolution of shaft 20. Accordingly, a time measured from the
reference zero time to the time first horizontal probe 12 and first
vertical probe 15 receive a signal is started when revolutional
probe 13 transmits a trigger signal to processor 10 in every
revolution. In cooperation with revolutional target 33,
revolutional probe 13 thus forms a "one per revolution sensor." The
operation of revolutional probe 13 and revolutional target 33 may
also provide information to allow processor 10 to calculate the
rotational speed of shaft 20. In one embodiment, the rotational
speed of shaft 20 may be determined by:
w=2.pi.(1/.DELTA.t),
where .DELTA.t is the difference between two consecutive trigger
signals sent from revolutional probe 13).
[0033] As shaft 20 rotates, first target 32 will pass once
proximate probes 12, 12a, 15, and 15a upon every revolution of
shaft 20. Similarly, as shaft 20 rotates, second target 34 will
pass once proximate probes 14, 14a, 17, and 17a upon every
revolution of shaft 20. The signals (e.g., laser light signals)
transmitted by probes 12, 12a, 15, or 15a, and 14, 14a, 17, or 17a
will be incident on targets 32 and 34, respectively, as those
targets 32 and 34 pass proximate the respective probes as shaft 20
rotates. Targets 32 and 34 may intensify and reflect the
transmitted signals incident on targets 32 and 34 which may
effectively form response signals (e.g., laser light signals formed
in response to the transmitted signals incident on targets 32, and
34) are received by probes 12, 12a, 15, or 15a, and 14, 14a, 17, or
17a which may then send corresponding signals to processor 10.
Processor 10 may determines and record the time at which the signal
reflected by target 32 is received by probes 12, 12a, 15, or 15a
and the time at which the signal reflected by target 34 is received
at probes 14, 14a, 17, or 17a. The difference between the
respective reception times of the reflected signals by probes 12,
12a, 15, or 15a, and 14, 14a, 17, or 17a may then be detected. For
example, a difference of time of as small as about 10 nanoseconds
may be detected.
[0034] The first horizontal probe 12, third horizontal probe 12a,
first vertical probe 15 and third vertical probe 15a transmit first
transmission first and second signals and receive first horizontal
first and second responses to/from the first target 32. The first
vertical probe 15, third vertical probe 15a, second vertical probe
17, and fourth vertical probe 17a transmit second vertical first
and second transmissions and receive second vertical first and
second responses to/from the second target 34.
[0035] The difference in time between the signal receptions by
probes 12, 12a, 14, 14a, 15, 15a, 17, and 17a may change as
different levels of torque are applied to rotating shaft 20. After
processor 10 has determined the difference in time, processor 10
can then determine an angular torsional displacement of shaft 20.
As an example, the torsional displacement measured in radians may
be calculated, assuming the circumferential positions of targets 32
and 34 on shaft 20 are the same (e.g., targets 32 and 34 are
circumferentially aligned), by multiplying .DELTA.t times w, where
.DELTA.t is the time difference between the receptions of signals
by probes (12, 12a, 15, and 15a) and probes (14, 14a, 17, and 17a)
and w is the rotational speed of shaft 20. The rotational speed w
of shaft 20 may be determined from the operation of revolutional
probe 13 and revolutional target 33 as discussed above.
[0036] Signals received by laser light probes 12, 12a, 14, 14a, 15,
15a, 17, and 17a when a measurable torque is imposed on shaft 20
may vary as a result of torsional displacement (i.e.,
circumferential twist). Targets 32 and 34 which were previously
circumferentially aligned therefore become circumferentially offset
from one another so that the respective signals reflected by
targets 32 and 34 are received by laser light probes (12, 12a, 15,
and 15a) and laser light probes (14, 14a, 17, and 17a) at different
times. This difference in time .DELTA.t may be multiplied by the
rotational speed of the shaft (w) to calculate the torsional
displacement in radians. Processor 10 may then calculate the torque
imposed on rotating shaft 20 based on its calculated torsional
displacement. In one embodiment, the torque may be calculated from
the torsional displacement using a finite element model analysis,
and power generated by gas turbine 40 may be determined based on
the calculated torque. In particular, torque on shaft 20 may be
calculated from the torsional displacement as follows. If shaft 20
comprises a uniform material at a constant temperature and its
cross-sectional area is uniform and constant over its entire
length, then torque may be calculated using the closed form
solution:
.tau. = ( .theta. ) ( G ) ( J ) ( L ) ##EQU00001##
[0037] Where .tau.=torque on shaft 20, .theta.=torsional
displacement in radians (angle change measured by probes (12, 12a,
15, and 15a) and probes (14, 14a, 17, and 17a) and calculated by
processor 10), G=shear modulus of the material of shaft 20 (e.g.,
available in engineering handbooks, calculated using
self-calibration), j=polar moment of inertia and L=axial distance
between probes 12/12a and 14/14a. The polar moment of inertia (j)
is the inherent stiffness of shaft 20 and can be calculated for a
solid circular cross section where R=radius of shaft 20, by:
j = ( .pi. ) ( R 4 ) 2 ##EQU00002##
[0038] The torque calculation becomes more complex to precisely
determine if any one or more of the following occur: Shear modulus
(G) changes along the length and/or radial direction (e.g., due to
temperature changes of the shaft material or use of a different
material), the cross-sectional area of shaft 20 is not uniform
(e.g., keyway notch), and/or the cross-sectional area is not
constant along the length of shaft 20.
[0039] While shaft 20 illustrated in the exemplary embodiment of
FIG. 2 is rotated by a gas turbine 40, those skilled in the art
will appreciate that shaft 20 may alternatively be rotated by
another machine such as a steam turbine, nuclear power generator or
internal combustion engine. Moreover, although shaft 20 transmits
the rotational force exerted on it from gas turbine 40 to rotate a
magnet 64 in power generator 60, those skilled in the art will
appreciate that shaft 20 can be alternatively connected to drive
other loads. For example, shaft 20, once rotated by a machine such
as turbine 40, can be used to drive other loads such as rotating a
propeller on a vehicle.
[0040] FIGS. 3-4 illustrate another exemplary embodiment of the
present invention. Reference numbers corresponding to parts
previously described for previous embodiments will remain the same.
Only the differences from previous embodiments will be discussed in
detail. While FIG. 2 illustrates shaft 20 as part of a simple cycle
power generation system, FIGS. 3-4 illustrate shaft 20 as part of a
combined cycle power generation system. Specifically, shaft 20
illustrated in FIGS. 3-4 is rotated by gas turbine 40 while steam
turbine 50 imposes a rotational force on generator shaft 62 of
power generator 60. Axial end 24a of shaft 20 is connected to
turbine shaft 42 of gas turbine 40 and axial end 24b of shaft 20 is
connected to steam turbine shaft 52 of steam turbine 50. Gas
turbine 40 rotates turbine shaft 42 to rotate shaft 20 and, in
turn, shaft 20 rotates steam turbine shaft 52 of steam turbine 50.
Thus, the torque imposed on shaft 20 by gas turbine 40 is
transmitted to steam turbine shaft 52 which then imposes a torque
on generator shaft 62. Generator shaft 62 is thus subject to the
combined rotational forces from steam turbine 50 and gas turbine
40. Magnet 64 of power generator 60 thus rotates as a result of
rotational forces provided by steam turbine 50 and gas turbine
40.
[0041] As discussed in the embodiment of FIG. 2, as shaft 20 is
rotated by gas turbine 40, signals transmitted from probes 12, 12a,
15, and 15a are reflected by targets 32 and 32a and probes 14, 14a,
17, and 17a are reflected by targets 34 and 34a, respectively, as
they revolve and pass underneath probes 12, 12a, 14, 14a, 15, 15a,
17, and 17a. The signals reflected from targets 32, 32a, 34 and 34a
are received by probes 12, 12a, 14, 14a, 15, 15a, 17, and 17a and
their respective times of arrival are measured. Processor 10 then
calculates the difference in the time at which signals are received
by probes 12, 12a, 14, 14a, 15, 15a, 17, and 17a to determine a
torsional displacement and then determines a torque imposed on
shaft 20 based upon its torsional displacement. Power generated by
gas turbine 40 can be calculated from the determination of
torque.
[0042] As shaft 20 twists when it is loaded, targets 32 and 34 will
be displaced from one another as discussed above. These targets 32
and 34 will also be displaced from one another if shaft 20
vibrates. The displacement from shaft vibration can be measured
through the use of additional targets 32a and 34a. By assessing the
time of arrival of at least one of the sets of targets 32 and 32a
(or 34 and 34a) within one revolution of shaft 20 and comparing it
to the expected time of arrival based on the actual distance
between the targets 32 and 32a and the rotational speed of shaft
20, the displacement from vibration can be calculated. For example,
if targets 32 and 32a are circumferentially offset from one another
by 180 degrees. (see FIG. 6), the respective times of arrival of
signals detected by probe 12 may be expected to be one-half of the
time required for one complete rotation. The time for a complete
rotation may be determined through the operation of revolutional
probe 13 and revolutional target 33 as discussed above. The
displacement of shaft 20 due to its vibration may then be
determined by the difference between the expected time difference
and the actual time difference that respective response signals
from targets 32 and 32a are detected by probes 12 and/or 12a and/or
the difference between the expected time difference and the actual
time difference that respective response signals from targets 34
and 34a are detected probe 14 and/or 14a. The total torsional
displacement may thus be determined by adding the displacement
caused by the vibration and the load displacement (i.e., the
torsional displacement caused by the rotational force imposed on
shaft 20). Accordingly, by bonding additional targets 32a and/or
34a to shaft 20 and detecting response signals therefrom utilizing
probes 12, 12a, 14, and/or 14a, a correctional value may be
determined for the torsional displacement resulting from the
rotational force imposed on shaft 20. Accuracy in the torsional
displacement measurement may therefore be enhanced.
[0043] In this embodiment, torque 27 may cause shaft 20 to
torsionally and/or axially displace along an axial length of shaft
20 causing a second end 23 of shaft 20 (shown in phantom) to move
axially and/or radially relative to a first end 25 of shaft 20. As
can be seen, second end 23 may displace proportionally relative to
torque 27 in a radial direction. A set of targets disposed about
shaft 20 may also be displaced by this torsional displacement
creating a difference between a set of probes on first end 25 and
second end 23.
[0044] Turning to FIG. 7, a schematic view of a target monitoring
system 200 disposed about a shaft 20 is shown according to
embodiments of the invention. In this embodiment, target monitoring
system 200 includes a first horizontal probe 12 and a first axial
probe 212 located proximate shaft 20 and target 32. First
horizontal probe 12 and first axial probe 212 are located a first
predetermined axial distance `d.sub.1` apart from one another. In
an embodiment, d.sub.1-2 may be an axial distance relative to shaft
20. In one embodiment, first predetermined axial distance d.sub.1
may be about 3 centimeters (cm). As a result of distance d.sub.1,
first horizontal probe 12 and first axial probe 212 may have unique
sight lines (shown in phantom) to target 32. These unique sidelines
may enable processor 10 to determine a first offset .DELTA.h.sub.1
between probes 12 and 212 which may be used to determine a first
gradient for target 32. Similarly, a second axial probe 214 and a
second horizontal probe 14 may be used to determine a second
gradient for a target 34 located proximate a second end 224 of
shaft 20. More specifically, as shown in FIG. 7, second horizontal
probe 14 and second axial probe 214 are located a second
predetermined axial distance `d.sub.2` apart from one another. In
an embodiment, as shown in FIG. 7, second predetermined axial
distance d.sub.2 may be substantially equal to first predetermined
axial distance d.sub.1 (e.g., about 3 cm). However, it may be
understood that first predetermined axial distance d.sub.1 and
second predetermined axial distance d.sub.2 do not need to be
substantially equal, as long as first predetermined axial distance
d.sub.1 and second predetermined axial distance d.sub.2 remain
constant during the determining process discussed herein. These
unique sidelines may enable processor 10 to determine a second
offset .DELTA.h.sub.2 between probes 14 and 214 which may be used
to determine a second gradient for target 34. The first gradient
for target 32 and the second gradient for target 34 may be compared
and the magnitude of any difference between the gradients may be
used to calculate a difference between torque reported without
respect to the gradients and actual torque. This calculated
difference, due to the difference between the gradients, may be
used to correct the reported torque measurement. Target monitoring
system 200 further includes end probe 211 which is disposed
proximate a first end 222 of shaft 20 and is configured to monitor
axial movement of shaft 20 during operation.
[0045] First predetermined axial distance d.sub.1 and second
predetermined axial distance d.sub.2 may be determined prior to
operation of turbine 2 (FIG. 1). Additionally, during operation of
turbine 2 (FIG. 1) and target monitoring system 200, signals from
probes 12, 212, 14 and 214, respectively, are measured. Processor
10, receiving signals from probes 12, 212, 14 and 214,
respectively, may then calculate first offset .DELTA.h.sub.1 for
target 32 and second offset .DELTA.h.sub.2 for target 34. Processor
10 may subsequently calculate the gradients for each respective
target 32, 34, relating to the measured axial movement discussed
herein, by:
Gradient = .DELTA. h d ##EQU00003##
[0046] Turning to FIG. 8, a target control system 500 is shown
including a first target 232 and a fifth target 234 communicatively
connected to a computing device 510 and a shaft 20 according to
embodiments of the invention. Target control system 500 includes a
computer infrastructure 502 that can perform the various processes
described herein. In particular, computer infrastructure 502 is
shown including computing device 510 which includes a target
displacement system 507, which enables computing device 510 to
monitor shaft 20 and targets 232 and 234 via probes 12, 14, 211,
212, and 214, and analyze and/or predict displacements and/or
movements of portions of shaft 20 by performing the process steps
of the disclosure. In an embodiment, computing device 510 may
determine a set of gradients for first target 232 and second target
234 during non-load conditions and then determine axial movement of
shaft 20 during operation via end probe 211. Computing device 510
may then determine a product of the gradient for each device and
the axial movement of shaft 20 and factor this product into torque
and/or power output determinations. In one embodiment, computing
device 510 may determine a displacement between a first end of
shaft 20 and a second end of shaft 20. Target control system 500
may be operated manually by a technician, automatically by
computing device 510, and/or in conjunction with a technician and
computing device 510.
[0047] As previously mentioned and discussed further below, target
displacement system 507 has the technical effect of enabling
computing device 510 to perform, among other things, the
displacement and/or shaft movement monitoring, adjustment and/or
regulation described herein. It is understood that some of the
various components shown in FIG. 8 can be implemented
independently, combined, and/or stored in memory for one or more
separate computing devices that are included in computing device
510. Further, it is understood that some of the components and/or
functionality may not be implemented, or additional schemas and/or
functionality may be included as part of target displacement system
507.
[0048] Computing device 510 is shown including a memory 512, a
processor unit (PU) 514, an input/output (I/O) interface 516, and a
bus 518. Further, computing device 510 is shown in communication
with an external I/O device/resource 520 and a storage system 522.
As is known in the art, in general, PU 514 executes computer
program code, such as thermal management system 507, that is stored
in memory 512 and/or storage system 522. While executing computer
program code, PU 514 can read and/or write data, such as graphical
user interface 530 and/or operational data 532, to/from memory 512,
storage system 522, and/or I/O interface 516. Bus 518 provides a
communications link between each of the components in computing
device 510. I/O device 520 can comprise any device that enables a
user to interact with computing device 510 or any device that
enables computing device 510 to communicate with one or more other
computing devices. Input/output devices (including but not limited
to keyboards, displays, pointing devices, etc.) can be coupled to
the system either directly or through intervening I/O
controllers.
[0049] In some embodiments, as shown in FIG. 8, target control
system 500 may include set of probes 12, 14, 211, 212, and 214
communicatively connected to shaft 20 via targets 232 and 234, and
communicatively connected to computing device 510 (e.g., via
wireless or hard-wired means). Targets 232 and 234 may obtain a set
of operational data 532 (e.g., displacements, locations, distances,
etc.) and transmit operational data 532 to computing device 510 for
processing with target displacement system 507 as a part of torque
and/or output determination calculations. In one embodiment,
computing device 510 may include system data 536 (e.g., distances
between targets, a length of shaft 20, a metallurgical composition
of shaft 20, etc.) and a graphical user interface 530 for display
of measurements and calculations to a technician.
[0050] In any event, computing device 510 can comprise any general
purpose computing article of manufacture capable of executing
computer program code installed by a user (e.g., a personal
computer, server, handheld device, etc.). However, it is understood
that computing device 510 is only representative of various
possible equivalent computing devices and/or technicians that may
perform the various process steps of the disclosure. To this
extent, in other embodiments, computing device 510 can comprise any
specific purpose computing article of manufacture comprising
hardware and/or computer program code for performing specific
functions, any computing article of manufacture that comprises a
combination of specific purpose and general purpose
hardware/software, or the like. In each case, the program code and
hardware can be created using standard programming and engineering
techniques, respectively. In one embodiment, computing device 510
may be/include a distributed control system.
[0051] Turning to FIG. 9, a schematic view of portions of a
multi-shaft combined cycle power plant 900 is shown. Combined cycle
power plant 900 may include, for example, a gas turbine 980
operably connected to a generator 970. Generator 970 and gas
turbine 980 may be mechanically coupled by a shaft 915, which may
transfer energy between a drive shaft (not shown) of gas turbine
980 and generator 970. Also shown in FIG. 9 is a heat exchanger 986
operably connected to gas turbine 980 and a steam turbine 992. Heat
exchanger 986 may be fluidly connected to both gas turbine 980 and
a steam turbine 992 via conventional conduits (numbering omitted).
Gas turbine 980 and/or steam turbine 992 may include target
monitoring system 200 of FIG. 7 or other embodiments described
herein. Heat exchanger 986 may be a conventional heat recovery
steam generator (HRSG), such as those used in conventional combined
cycle power systems. As is known in the art of power generation,
HRSG 986 may use hot exhaust from gas turbine 980, combined with a
water supply, to create steam which is fed to steam turbine 992.
Steam turbine 992 may optionally be coupled to a second generator
system 970 (via a second shaft 915). It is understood that
generators 970 and shafts 915 may be of any size or type known in
the art and may differ depending upon their application or the
system to which they are connected. Common numbering of the
generators and shafts is for clarity and does not necessarily
suggest these generators or shafts are identical. In another
embodiment, shown in FIG. 10, a single shaft combined cycle power
plant 990 may include a single generator 970 coupled to both gas
turbine 980 and steam turbine 992 via a single shaft 915. Steam
turbine 992 and/or gas turbine 980 may include target monitoring
system 200 of FIG. 7 or other embodiments described herein.
[0052] Although discussed herein as being utilized within power
generation systems (e.g., gas turbine systems), it is understood
that target monitoring system 200 may be utilized by system or
component utilizing a shaft for power transmission. For example,
target monitoring system 200 may be utilized by systems including,
but not limited to: power generation systems, ship propulsion
systems, aircraft propulsion systems, etc.
[0053] Additional details for this invention may be found in U.S.
Pat. No. 7,415,363.
[0054] The apparatus and devices of the present disclosure are not
limited to any one particular engine, turbine, jet engine,
generator, power generation system or other system, and may be used
with other aircraft systems, power generation systems and/or
systems (e.g., combined cycle, simple cycle, nuclear reactor,
etc.). Additionally, the apparatus of the present invention may be
used with other systems not described herein that may benefit from
the shaft displacement and/or movement monitoring of the apparatus
and devices described herein.
[0055] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the disclosure. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
[0056] 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 examples are intended to be within the scope
of the claims if they have 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.
* * * * *