TECHNICAL FIELD
5 [0001] The present disclosure relates to drain removal monitoring equipment.
This application claims the priority of Japanese Patent Application No. 2020-87905 filed
on May 20, 2020, the content of which is incorporated herein by reference.
BACKGROUND
10 [0002] In a steam turbine, collision of water droplets on a rotor blade may cause erosion
damage to the rotor blade. Patent Document 1 discloses a steam turbine capable of removing
drain by forming a slit, through which an internal space inside a hollow stator vane and the
outside of the stator vane communicate with each other, in a vane surface of the stator vane,
and drawing water (liquid phase) adhering to the surface of the stator vane into the internal
15 space via the slit due to a pressure difference. In the steam turbine, drain is removed by
adjusting the pressure difference between the outside of the stator vane and the internal space
to an appropriate pressure difference according to a turbine load fluctuation.
Citation List
20 Patent Literature
[0003]
Patent Document 1: JPS62-157206A
SUMMARY
25 Technical Problem
[0004] However, not only the liquid phase but also a gas phase is draw into the internal
space via the slit. Thus, it is actually unknown whether drain is properly removed. In order
to ascertain whether drain is properly removed, it is necessary to measure the flow rates of both
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the liquid phase and the gas phase drawn into the internal space via the slit.
[0005] In view of the above, an object of at least one embodiment of the present disclosure
is to provide drain removal monitoring equipment capable of ascertaining whether drain is
properly removed.
5
Solution to Problem
[0006] In order to achieve the above object, a drain removal monitoring equipment
according to the present disclosure is a drain removal monitoring equipment for monitoring, in
a steam turbine, drain removal performed by drawing a fluid outside at least one hollow stator
10 vane including an internal space into the internal space via a slit formed in a surface of the stator
vane, that includes: a gas-liquid separation device forseparating the fluid drawn into the internal
space into a liquid phase and a gas phase; a liquid-phase flow measurement device for
measuring a flow rate of the liquid phase separated by the gas-liquid separation device; a gasphase flow measurement device for measuring a flow rate of the gas phase separated by the
15 gas-liquid separation device; a liquid-phase return line through which the liquid-phase flow
measurement device and the steam turbine communicate with each other; and a gas-phase return
line through which the gas-phase flow measurement device and the steam turbine communicate
with each other.
20 Advantageous Effects
[0007] According to drain removal monitoring equipment of the present disclosure, since
the flow rates of both a liquid phase and a gas phase in a fluid drawn into an internal space of a
stator vane of a steam turbine via a slit formed in the stator vane are measured, it is possible to
ascertain whether drain is properly removed.
25
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a schematic view showing the configuration of drain removal monitoring
equipment according to Embodiment 1 of the present disclosure.
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FIG. 2 is a graph showing a comparison between a case where an orifice nozzle is used
and a case where a Laval nozzle is used as a critical nozzle used in a gas-phase flow
measurement device of the drain removal monitoring equipment according to Embodiment 1
of the present disclosure.
5 FIG. 3 is a block configuration diagram showing the preferred configuration of the drain
removal monitoring equipment for diagnosing an abnormality in drain removal from the flow
rates of a liquid phase and a gas phase in the drain removal monitoring equipment according to
Embodiment 1 of the present disclosure.
FIG. 4 is a graph showing an example of abnormality detection in drain removal.
10 FIG. 5 is a graph showing an example of abnormality detection in drain removal.
FIG. 6 is a graph showing an example of abnormality detection in drain removal.
FIG. 7 is a schematic view showing the configuration of the drain removal monitoring
equipment according to Embodiment 2 of the present disclosure.
FIG. 8 is a schematic view showing the configuration of the drain removal monitoring
15 equipment according to Embodiment 3 of the present disclosure.
FIG. 9 is a schematic view showing the configuration of the drain removal monitoring
equipment according to Embodiment 4 of the present disclosure.
FIG. 10 is a schematic view showing the configuration of the drain removal monitoring
equipment according to Embodiment 5 of the present disclosure.
20 FIG. 11 is a graph schematically showing the relationship between the pressure ratio and
the flow rate in the gas-phase flow measurement device including only one measurement
mechanism.
FIG. 12 is a graph schematically showing the relationship between the pressure ratio and
the flow rate in the gas-phase flow measurement device including a plurality of measurement
25 mechanisms.
DETAILED DESCRIPTION
[0009] Hereinafter, drain removal monitoring equipment according to the embodiments of
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the present disclosure will be described with reference to the drawings. The embodiments
each indicate one aspect of the present disclosure, do not intend to limit the disclosure, and can
optionally be modified within a range of a technical idea of the present disclosure.
[0010] (Embodiment 1)
5
As shown in FIG. 1, drain removal monitoring equipment 10 according to Embodiment 1
is provided to monitor, in a steam turbine 1, drain removal performed by drawing a fluid outside
at least one hollow stator vane 2 including an internal space 3 into the internal space 3 via a slit
10 4 formed in a surface of the stator vane 2. A diaphragm 5 connected to the stator vane 2 is
formed into a hollow shape including an internal space 6, and the internal space 6 and the
internal space 3 communicate with each other. Although not shown in FIG. 1, the steam
turbine 1 includes a turbine with the stator vane 2, a turbine outlet exhaust casing, and a
condenser casing.
15 [0011] The drain removal monitoring equipment 10 includes a gas-liquid separation
device11 for separating a fluid with a liquid phase and a gas phase into a liquid phase and a gas
phase, a liquid-phase flow measurement device 12 for measuring the flow rate of the liquid
phase separated by the gas-liquid separation device 11, a gas-phase flow measurement device
13 for measuring the flow rate of the gas phase separated by the gas-liquid separation device
20 11, a liquid-phase return line 14 through which the liquid-phase flow measurement device 12
and the steam turbine 1 communicate with each other, and a gas-phase return line 15 through
which the gas-phase flow measurement device 13 and the steam turbine 1 communicate with
each other.
[0012] The drain removal monitoring equipment 10 further includes a two-phase flow line
25 16 through which the internal space 6 in the diaphragm 5 and the gas-liquid separation device
11 communicate with each other. Since the internal space 6 and the internal space 3
communicate with each other, the two-phase flow line 16 causes the internal space 3 and the
gas-liquid separation device 11 to communicate with each other via the internal space 6. In
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addition, the drain removal monitoring equipment 10 further includes a gas-phase flow line 17
through which the gas-liquid separation device 11 and the gas-phase flow measurement device
13 communicate with each other.
[0013] The configuration of the gas-liquid separation device 11 is not particularly limited,
5 and it is possible to use, for example, a device of a corrugated plate type or a demister type by
mesh or the like, or a cyclone type cyclone separator. However, the cyclone type configuration
has a wider flow rate range capable of maintaining gas-liquid separation with low pressure loss
and high performance than the configuration of mesh or the like, and it is possible to follow a
change in measurement conditions or expand a control range. Therefore, the cyclone
10 separator is preferably used as the gas-liquid separation device 11.
[0014] The configuration of the liquid-phase flow measurement device 12 is not
particularly limited, and a measurement device with any configuration can be used. As an
example of the liquid-phase flow measurement device 12, it is possible to use a device that
includes a tank part 21 for storing the liquid phase separated by the gas-liquid separation device
15 11 and a liquid-phase amount detection part 22 for detecting the amount of the liquid phase in
the tank part 21. As the liquid-phase amount detection part 22, it is possible to use a liquid
level meter for detecting the liquid level of the liquid phase in the tank part 21. As the liquid
level meter, it is possible to use a float-type meter, or a meter for detecting the liquid level by
light, infrared rays, ultrasonic waves, or the like.
20 [0015] If the liquid-phase flow measurement device 12 has a configuration including the
tank part 21, an end of the liquid-phase return line 14 is preferably connected to a bottom of the
tank part 21. Further, in this case, the liquid-phase return line 14 may be provided with a
drainage valve 23 that can automatically be opened and closed according to a value detected by
the liquid-phase amount detection part 22. For example, an upper limit value is set in advance
25 for the value detected by the liquid-phase amount detection part 22, and the drainage valve 23
can be opened if the value detected by the liquid-phase amount detection part 22 reaches the
upper limit value.
[0016] The configuration of the gas-phase flow measurement device 13 is not particularly
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limited, and a measurement device with any configuration can be used. As an example of the
gas-phase flow measurement device 13, it is possible to use a device provided with a plurality
of measurement mechanisms 30 each of which includes a pressure gauge 31 for measuring a
pressure of the gas phase, a critical nozzle 32 disposed downstream of the pressure gauge 31,
5 and an opening and closing valve 33 disposed downstream of the critical nozzle 32. As the
critical nozzle 32, although any nozzle such as an orifice nozzle or a Laval nozzle can be used,
the Laval nozzle is preferably used for the reasons described later.
[0017] In FIG. 1, the gas-phase flow measurement device 13 includes six measurement
mechanisms 30. However, the number is not limited to six, and the gas-phase flow
10 measurement device 13 may include only one measurement mechanism 30 or may include any
number, other than six, of measurement mechanisms 30. Each measurement mechanism 30
includes a gas-phase flow pipe 34 through which the gas phase flows. The gas-phase flow
pipes 34 may all have the same inner diameter or may all have different inner diameters, or
some of the gas-phase flow pipes 34 may have the same inner diameter and the others may have
15 the different inner diameters.
[0018]
Next, an operation of the drain removal monitoring equipment 10 according to
Embodiment 1 of the present disclosure will be described. During an operation of the steam
20 turbine 1, a fluid is drawn into the internal space 3 via the slit 4. Herein, the drawn fluid
includes the liquid phase adhering to the surface of the stator vane 2, that is, liquid water or a
working fluid of the steam turbine 1 passing through the stator vane 2, that is, the gas phase and
the liquid phase in steam. The fluid drawn into the internal space 3 flows into the two-phase
flow line 16 via the internal space 6 and flows through the two-phase flow line 16.
25 [0019] The fluid flowing through the two-phase flow line 16 flows into the gas-liquid
separation device 11, and isseparated into the liquid phase and the gas phase. The liquid phase,
that is, the liquid water flows into the tank part 21 of the liquid-phase flow measurement device
12 and is stored in the tank part 21. On the other hand, the gas phase flows through the gas7
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phase flow line 17 and flows into the gas-phase flow measurement device 13.
[0020] In the liquid-phase flow measurement device 12, the liquid-phase amount detection
part 22 detects transition of the water level of the water in the tank part 21. Since the amount
of the water in the tank part 21 can be calculated from the water level of the water in the tank
5 part 21, based on the value detected by the liquid-phase amount detection part 22, transition of
the flow rate of the liquid phase in the fluid drawn into the internal space 3 is obtained.
[0021] By opening the drainage valve 23 if the water level in the tank part 21 reaches the
upper limit value, the water in the tank part 21 is drained from the tank part 21 and flows into
the steam turbine 1, or more specifically a condenser (not shown) via the liquid-phase return
10 line 14. As described above, since the liquid phase can automatically be drained from the tank
part 21, long-term monitoring is possible.
[0022] On the other hand, in the gas-phase flow measurement device 13, the gas phase
flowsinto at least one measurement mechanism 30. If the gas-phase flow measurement device
13 includes the plurality of measurement mechanisms 30, the number of measurement
15 mechanisms 30 into which the gas phase flows can be adjusted by opening and closing the
opening and closing valve 33 of each measurement mechanism 30, thereby making it possible
to adjust a pressure difference between upstream and downstream of the slit 4, and the flow rate
of the two-phase flow drawn into the internal space 3 via the slit 4, the details of which are to
be described later in Embodiment 5.
20 [0023] The gas phase having flown into the measurement mechanism 30 flows into the
critical nozzle 32 after the pressure is measured by the pressure gauge 31. The gas phase
having flown into the critical nozzle 32 flows out of the critical nozzle 32 with a flow passage
area being enlarged again after the flow passage area is narrowed. By using the critical nozzle
32 in the gas-phase flow measurement device 13, the flow rate of the gas-phase can be measured
25 only by an upstream pressure of the critical nozzle 32.
[0024] FIG. 2 shows a comparison between a case where an orifice nozzle is used and a
case where a Laval nozzle is used as the critical nozzle 32. A pressure P1 at a position L1
before the flow passage area is narrowed in the critical nozzle 32 is the pressure measured by
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the pressure gauge 31 (see FIG. 1), and is the same for any nozzles. P2
Next, an example of diagnosing an abnormality in drain removal from the flow rates of
the liquid phase and the gas phase respectively measured by the liquid-phase flow measurement
device 12 and the gas-phase flow measurement device 13 will be described. In order to
perform such diagnosis, as shown in FIG. 3, the drain removal monitoring equipment 10
25 preferably includes a control device 20 electrically connected to the liquid-phase flow
measurement device 12 and the gas-phase flow measurement device 13.
[0028] The flow rates of the liquid phase and the gas phase respectively measured by the
liquid-phase flow measurement device 12 and the gas-phase flow measurement device 13 are
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transmitted to the control device 20. The control device 20 is preset with an upper limit value
and a lower limit value for the flow rate of the liquid phase and an upper limit value and a lower
limit value for the flow rate of the gas phase, and the abnormality in drain removal is detected
based on the respective flow rates of the liquid phase and the gas phase transmitted and the
5 upper limit values and the lower limit values for the respective flow rates of the liquid phase
and the gas phase. As long as the flow rate of the liquid phase and the flow rate of the gas
phase fluctuate between the respective upper limit values and lower limit values, the control
device 20 determines that drain is properly removed.
[0029] For example, as shown in FIG. 4, if the flow rate of the gas phase may decrease and
10 fall below the lower limit value even though the flow rate of the liquid phase fluctuates between
the upper limit value and the lower limit value, the control device 20 (see FIG. 3) determines
that there is an abnormality in which the fluid drawn into the internal space of the stator vane 2
(see FIG. 1) is reversely injected from the slit 4 (see FIG. 1). Occurrence of such abnormality
increases the risk of erosion damage. In case such abnormality is detected, the control device
15 20 operates the opening and closing valve 33 (see FIG. 1) to increase the pressure ratio between
upstream and downstream of the slit 4, thereby increasing the flow rate of the gas phase. If
such control is performed, the flow rate of the gas phase increases and fluctuates between the
upper limit value and the lower limit value, and drain is properly removed.
[0030] For example, as shown in FIG. 5, if the flow rate of the gas phase may increase and
20 exceed the upper limit value even though the flow rate of the liquid phase fluctuates between
the upper limit value and the lower limit value, the control device 20 (see FIG. 3) determines
that there is a possibility of an increase in gas pass due to deformation in the slit 4 (see FIG. 1)
or the like. If such state is left, an output of the steam turbine 1 (see FIG. 1) will decrease.
In case such abnormality is detected, the control device 20 operates the opening and closing
25 valve 33 (see FIG. 1) within a range where the flow rate of the liquid phase does not fluctuate
to reduce the pressure ratio between upstream and downstream of the slit 4. If such control is
performed, the flow rate of the gas phase decreases and fluctuates between the upper limit value
and the lower limit value, and drain is properly removed.
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[0031] For example, as shown in FIG. 6, if the flow rate of the liquid phase may increase
and exceed the upper limit value even though the flow rate of the gas phase fluctuates between
the upper limit value and the lower limit value, the control device 20 (see FIG. 3) determines
that there is a possibility of an increase in wetness of main steam. Such state also increases
5 the risk of erosion damage. However, since such abnormality cannot be recovered by control,
early notification of the abnormality can be used as preventive measures for troubles, such as
advancing a regular inspection period.
[0032] Thus, the control device 20 can automatically detect the occurrence of the
abnormality in drain removal and its cause.
10 [0033] In Embodiment 1, in the case where the drain removal monitoring equipment 10
includes the control device 20, it may be configured such that the control device 20 is set with
the upper limit value for the value detected by the liquid-phase amount detection part 22, and
the drainage valve 23 is opened if the value detected by the liquid-phase amount detection part
22 reaches the upper limit value.
15 [0034] (Embodiment 2)
Next, the drain removal monitoring equipment according to Embodiment 2 will be
described. The drain removal monitoring equipment according to Embodiment 2 is obtained
by adding, to Embodiment 1, a bypass line through which the two-phase flow line 16 and the
gas-phase return line 15 communicate with each other. In Embodiment 2, the same constituent
20 elements as those in Embodiment 1 are associated with the same reference characters and not
described again in detail.
[0035] As shown in FIG. 7, the drain removal monitoring equipment 10 according to
Embodiment 2 of the present disclosure includes a bypass line 40 through which the two-phase
flow line 16 and the gas-phase return line 15 communicate with each other. The bypass line
25 40 is provided with an opening and closing valve 41, and the two-phase flow line 16 is provided
with an opening and closing valve 18 downstream of a connection position with the bypass line
40. Other configurations are the same as Embodiment 1.
[0036] In Embodiment 2, when the flow rates of the liquid phase and the gas phase are
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measured, the opening and closing valve 18 is opened and the opening and closing valve 41 is
closed. On the other hand, if it is not necessary to measure the flow rates of the liquid phase
and the gas phase, the fluid drawn into the internal space 3 can be returned to the steam turbine
1 via the bypass line 40 and the gas-phase return line 15 by closing the opening and closing
5 valve 18 and opening the opening and closing valve 41. Thus, it is possible to reduce power
consumption for flow measurement. Further, it is also possible to perform maintenance of the
liquid-phase flow measurement device and the gas-phase flow measurement device while
continuing the operation of the steam turbine 1.
[0037] (Embodiment 3)
10 Next, the drain removal monitoring equipment according to Embodiment 3 will be
described. The drain removal monitoring equipment according to Embodiment 3 is obtained
by adding, to Embodiment 1 or 2, a first communication line through which the tank part 21
and the gas-phase return line 15 communicate with each other. Hereinafter, Embodiment 3
will be described with a configuration obtained by adding the first communication line to the
15 configuration of Embodiment 2. However, Embodiment 3 may be configured by adding the
first communication line to the configuration of Embodiment 1. In Embodiment 3, the same
constituent elements as those in Embodiment 2 are associated with the same reference
characters and not described again in detail.
[0038] As shown in FIG. 8, the drain removal monitoring equipment 10 according to
20 Embodiment 3 of the present disclosure includes a first communication line 50 through which
the tank part 21 and the gas-phase return line 15 communicate with each other. The first
communication line 50 is provided with an opening and closing valve 51. Other
configurations are the same as Embodiment 2.
[0039] The liquid phase separated by the gas-liquid separation device 11 is transferred to
25 the tank part 21 due to a pressure difference between the gas-liquid separation device 11 and
the tank part 21. However, if the pressure difference is small, the liquid phase is less likely to
be transferred to the tank part 21. To cope therewith, in Embodiment 3, if the opening and
closing valve 51 is opened, the pressure in the tank part 21 can be made equal to the downstream
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pressure of the gas-phase flow measurement device 13 via the first communication line 50,
making it possible to increase the pressure difference. Consequently, the transfer of the liquid
phase from the gas-liquid separation device 11 to the tank part 21 is promoted, and reliability
of flow measurement of the liquid phase can be enhanced.
5 [0040] (Embodiment 4)
Next, the drain removal monitoring equipment according to Embodiment 4 will be
described. The drain removal monitoring equipment according to Embodiment 4 is obtained
by adding, to Embodiment 3, a second communication line through which the gas-phase flow
line 17 and the first communication line 50 communicate with each other. In Embodiment 4,
10 the same constituent elements as those in Embodiment 3 are associated with the same reference
characters and not described again in detail.
[0041] As shown in FIG. 9, the drain removal monitoring equipment 10 according to
Embodiment 4 of the present disclosure includes a second communication line 60 through
which the gas-phase flow line 17 and the first communication line 50 communicate with each
15 other. The second communication line 60 is provided with an opening and closing valve 61.
Other configurations are the same as Embodiment 3.
[0042] In Embodiment 4, if the opening and closing valve 61 is opened, the liquid phase
staying in the gas-phase flow line 17 can be transferred to the tank part 21 via the second
communication line 60, making it possible to improve reliability of flow measurement of the
20 gas phase.
[0043] (Embodiment 5)
Next, the drain removal monitoring equipment according to Embodiment 5 will be
described. The drain removal monitoring equipment according to Embodiment 5 is obtained
by modifying any of Embodiments 1 to 4 to include a plurality of stator vanes 2 to be measured.
25 Hereinafter, Embodiment 5 will be described with a configuration obtained by modifying the
configuration of Embodiment 1 to include the plurality of stator vanes 2 to be measured.
However, Embodiment 5 may be configured by modifying any of Embodiments 2 to 4 to
include the plurality of stator vanes 2 to be measured. In Embodiment 5, the same constituent
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elements as those in Embodiment 1 are associated with the same reference characters and not
described again in detail.
[0044]
5 As shown in FIG. 10, in the drain removal monitoring equipment 10 according to
Embodiment 5 of the present disclosure, an upstream end of the two-phase flow line 16
branches into four branch pipes 16a, 16b, 16c, 16d, and the respective branch pipes are provided
with opening and closing valves 71a, 71b, 71c, 71d. The two-phase flow line 16 is provided
with the opening and closing valve 18. The branch pipes 16a, 16b, 16c, 16d are respectively
10 connected to diaphragms 5a, 5b, 5c, 5d so as to communicate with internal spaces 6a, 6b, 6c,
6d which are formed in the diaphragms 5a, 5b, 5c, 5d respectively connected to four different
stator vanes 2a, 2b, 2c, 2d. Since the internal spaces 6a, 6b, 6c, 6d and respective internal
spaces 3a, 3b, 3c, 3d of the stator vanes 2a, 2b, 2c, 2d communicate with each other, the twophase flow line 16 causes the internal spaces 3a, 3b, 3c, 3d and the gas-liquid separation device
15 11 to communicate with each other via the internal spaces 6a, 6b, 6c, 6d and the branch pipes
16a, 16b, 16c, 16d. The configuration where the upstream end of the flow line 16 branches
into the four branch pipes is merely an example, and a configuration may be adopted where the
flow line 16 branches into two or three, or even at least five branch pipes. Other
configurations are the same as Embodiment 1.
20 [0045]
In Embodiment 5, the gas-phase flow measurement device 13 includes six measurement
mechanisms 30a, 30b, 30c, 30d, 30e, 30f, and if gas-phase flow pipes 34a, 34b, 34c, 34d, 34e,
34f of the respective measurement mechanisms have different inner diameters, as shown in
25 Table 1, with combination of open and closed states of opening and closing valves 33a, 33b,
33c, 33d, 33e, 33f of the respective measurement mechanisms (the open opening and closing
valves are marked with circles in Table 1), it is possible to independently adjust the flow rate
of the two-phase flow drawn from slits 4a, 4b, 4c, 4d of the respective stator vanes and the
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pressure ratio between upstream and downstream of the slits 4a, 4b, 4c, 4d of the respective
stator vanes. In Table 1, the configuration is assumed where the inner diameters of the
respective gas-phase flow pipes 34a, 34b, 34c, 34d, 34e, 34f are different, and the inner
diameters increase in this order.
5 [0046] [Table 1]
Flow
rate
Opening and closing valve
33a 33b 33c 33d 33e 33f
Low
High
○
○
○
○
○
○
○ ○
○ ○
∙
∙
∙
○ ○ ○ ○ ○
○ ○ ○ ○ ○ ○
[0047] For example, in the gas-phase flow measurement device 13 including only one
measurement mechanism, as shown in FIG. 11, if the flow rate of the gas phase decreases due
to a change in measurement target from the stator vane 2a to the stator vane 2b, the relationship
between the pressure ratio and the flow rate is fixed at one point, and the flow measurement at
10 an appropriate pressure ratio may be impossible. By contrast, in the gas-phase flow
measurement device 13 including the plurality of measurement mechanisms, with the
combination of the open and closed states of the opening and closing valves 33a, 33b, 33c, 33d,
33e, 33f, for example, as shown in FIG. 12, it is possible to adjust the flow rate and pressure
ratio independently of each other, such as being able to change the flow rate even at the same
15 pressure ratio, and drain can be removed under appropriate conditions.
[0048] In Embodiment 5, the plurality of physically separate stator vanes 2a to 2d have
been described as the example of the plurality of measurement targets. However, the present
disclosure is not limited to this form. Embodiment 5 assumes that one and the same stator
vane having different measurement timings, that is, a plurality of measurements for the one and
20 the same stator vane are also the plurality of measurement targets. In such a case, the upstream
15
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end of the two-phase flow line 16 need not branch into the plurality of branch pipes, but the
same configuration as in Embodiment 1 may be adopted.
[0049] The contents described in the above embodiments would be understood as follows,
for instance.
5 [0050] [1] A drain removal monitoring equipment according to one aspect is a drain
removal monitoring equipment (10) for monitoring, in a steam turbine (1), drain removal
performed by drawing a fluid outside at least one hollow stator vane (2) including an internal
space (3) into the internal space (3) via a slit (4) formed in a surface of the stator vane (2), that
includes: a gas-liquid separation device (11) for separating the fluid drawn into the internal
10 space (3) into a liquid phase and a gas phase; a liquid-phase flow measurement device (12) for
measuring a flow rate of the liquid phase separated by the gas-liquid separation device (11); a
gas-phase flow measurement device (13) for measuring a flow rate of the gas phase separated
by the gas-liquid separation device (11); a liquid-phase return line (14) through which the
liquid-phase flow measurement device (12) and the steam turbine (1) communicate with each
15 other; and a gas-phase return line (15) through which the gas-phase flow measurement device
(13) and the steam turbine (1) communicate with each other.
[0051] According to drain removal monitoring equipment of the present disclosure, since
the flow rates of both the liquid phase and the gas phase in the fluid drawn into the internal
space of the stator vane of the steam turbine via a slit formed in the stator vane are measured,
20 it is possible to ascertain whether drain is properly removed.
[0052] [2] A drain removal monitoring equipment according to another aspect is the drain
removal monitoring equipment as defined in [1], that includes: a two-phase flow line (16)
through which the internal space (3) and the gas-liquid separation device (11) communicate
with each other; and a bypass line (40) through which the two-phase flow line (16) and the gas25 phase return line (15) communicate with each other.
[0053] With such configuration, if it is not necessary to measure the flow rates of the liquid
phase and the gas phase, the fluid drawn into the internal space can be returned to the steam
turbine via the bypass line and the gas-phase return line. Thus, it is possible to reduce power
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consumption for flow measurement. Further, it is also possible to perform maintenance of the
liquid-phase flow measurement device and the gas-phase flow measurement device while
continuing the operation of the steam turbine.
[0054] [3] A drain removal monitoring equipment according to still another aspect is the
5 drain removal monitoring equipment as defined in [1] or [2], where the liquid-phase flow
measurement device (12) includes a tank part (21) for storing the liquid phase, and the drain
removal monitoring equipment includes a first communication line (50) through which the tank
part (21) and the gas-phase return line (15) communicate with each other.
[0055] The liquid phase separated by the gas-liquid separation device is transferred to the
10 tank part due to a pressure difference between the gas-liquid separation device and the tank part.
However, if the pressure difference is small, the liquid phase is less likely to be transferred to
the tank part. To cope therewith, with the above configuration [3], since the pressure
difference can be increased, the transfer of the liquid phase from the gas-liquid separation
device to the tank part is promoted, and reliability of flow measurement of the liquid phase can
15 be enhanced.
[0056] [4] A drain removal monitoring equipment according to yet another aspect is the
drain removal monitoring equipment as defined in [3], that includes: a gas-phase flow line (17)
through which the gas-liquid separation device (11) and the gas-phase flow measurement device
(13) communicate with each other; and a second communication line (60) through which the
20 gas-phase flow line (17) and the first communication line (50) communicate with each other.
[0057] With such configuration, the liquid phase staying in the gas-phase flow line can be
transferred to the tank part, making it possible to improve reliability of flow measurement of
the gas phase.
[0058] [5] A drain removal monitoring equipment according to yet another aspect is the
25 drain removal monitoring equipment as defined in any one of [1] to [4], where the gas-phase
flow measurement device (13) includes a plurality of measurement mechanisms (30), and each
of the plurality of measurement mechanisms (30) includes: a pressure gauge (31) for measuring
a pressure of the gas phase; a critical nozzle (32) disposed downstream of the pressure gauge
17
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(31); and an opening and closing valve (33) disposed upstream or downstream of the pressure
gauge (31) and the critical nozzle (32).
[0059] With such configuration, the number of measurement mechanisms used for flow
measurement of the gas-phase can be adjusted by opening and closing the opening and closing
5 valve of each measurement mechanism. Thus, even if the stator vanes to be measured are
changed or even if the number of stator vanes to be measured is changed, conditions between
the pressure difference between upstream and downstream of the slit and the flow rate of the
two-phase flow including the liquid phase and the gas phase are appropriately adjusted by
adjusting the number of used measurement instruments, making it possible to appropriately
10 perform flow measurement of the gas phase.
[0060] [6] A drain removal monitoring equipment according to yet another aspect is the
drain removal monitoring equipment as defined in [5], where the critical nozzle (32) is a Laval
nozzle.
[0061] By using the critical nozzle in the gas-phase flow measurement device, the flow rate
15 of the gas-phase can be measured only by an upstream pressure of the critical nozzle.
However, if the downstream pressure of the gas-phase flow measurement device increases due
to operating conditions of the steam turbine, the critical pressure ratio may not be reached in
the critical nozzle. Even if the downstream pressure of the gas-phase flow measurement
device increases, the possibility of reaching the critical pressure ratio can be increased by using
20 the Laval nozzle as the critical nozzle, making it possible to enhance reliability of flow
measurement of the gas phase.
[0062] [7] A drain removal monitoring equipment according to yet another aspect is the
drain removal monitoring equipment as defined in any one of [1] to [6], where the gas-liquid
separation device (11) is a cyclone separator.
25 [0063] With such configuration, it is possible to perform gas-liquid separation for the flow
rate of a fluid in a wide range.
[0064] [8] A drain removal monitoring equipment according to yet another aspect is the
drain removal monitoring equipment as defined in any one of [1] to [7], where the liquid-phase
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flow measurement device (12) includes: a tank part (21) for storing the liquid phase; and a
liquid-phase amount detection part (22) for detecting an amount of the liquid phase in the tank
part (21).
[0065] With such configuration, it is possible to acquire the flow rate of the liquid phase
5 over time.
[0066] [9] A drain removal monitoring equipment according to yet another aspect is the
drain removal monitoring equipment as defined in [8], where the liquid-phase return line (14)
is connected to the tank part (21), and the liquid-phase return line (14) is provided with a
drainage valve (23) configured to open if a value detected by the liquid-phase amount detection
10 part (22) reaches a preset upper limit value.
[0067] With such configuration, since the liquid phase can automatically be drained from
the tank part if the liquid-phase amount in the tank part reaches the upper limit value, long-term
monitoring is possible.
[0068] [10] A drain removal monitoring equipment according to yet another aspect is the
15 drain removal monitoring equipment as defined in any one of [1] to [9], that includes a control
device (20) to which the flow rate of the liquid phase and the flow rate of the gas phase measured
by the liquid-phase flow measurement device (12) and the gas-phase flow measurement device
(13) are transmitted. The control device (20) is preset with an upper limit value and a lower
limit value for the flow rate of the liquid phase, and an upper limit value and a lower limit value
20 for the flow rate of the gas phase. The control device (20) detects an abnormality in the drain
removal based on the flow rate of the liquid phase and the flow rate of the gas phase respectively
transmitted from the liquid-phase flow measurement device (12) and the gas-phase flow
measurement device (13), and the upper limit value and the lower limit value for the flow rate
of the liquid phase and the upper limit value and the lower limit value for the flow rate of the
25 gas phase.
[0069] With such configuration, it is possible to automatically detect occurrence of the
abnormality in drain removal and its cause.
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Reference Signs List
[0070]
1 Steam turbine
2 Stator vane
5 3 Internal space
4 Slit
10 Drain removal monitoring equipment
11 Gas-liquid separation device
12 Liquid-phase flow measurement device
10 13 Gas-phase flow measurement device
14 Liquid-phase return line
15 Gas-phase return line
16 Two-phase flow line
20 Control device
15 21 Tank part
22 Liquid-phase amount detection part
23 Drainage valve
30 Measurement mechanism
31 Pressure gauge
20 32 Critical nozzle
33 Opening and closing valve
40 Bypass line
50 First communication line
60 Second communication line
25
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CLAIMS
1. A drain removal monitoring equipment for monitoring, in a steam turbine, drain removal
performed by drawing a fluid outside at least one hollow stator vane including an internal space
5 into the internal space via a slit formed in a surface of the stator vane, comprising:
a gas-liquid separation device for separating the fluid drawn into the internal space into a
liquid phase and a gas phase;
a liquid-phase flow measurement device for measuring a flow rate of the liquid phase
separated by the gas-liquid separation device;
10 a gas-phase flow measurement device for measuring a flow rate of the gas phase separated
by the gas-liquid separation device;
a liquid-phase return line through which the liquid-phase flow measurement device and
the steam turbine communicate with each other; and
a gas-phase return line through which the gas-phase flow measurement device and the
15 steam turbine communicate with each other.
2. The drain removal monitoring equipment according to claim 1, comprising:
a two-phase flow line through which the internal space and the gas-liquid separation
device communicate with each other; and
20 a bypass line through which the two-phase flow line and the gas-phase return line
communicate with each other.
3. The drain removal monitoring equipment according to claim 1 or 2,
wherein the liquid-phase flow measurement device includes a tank part for storing the
25 liquid phase, and
wherein the drain removal monitoring equipment comprises a first communication line
through which the tank part and the gas-phase return line communicate with each other.
21
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4. The drain removal monitoring equipment according to claim 3, comprising:
a gas-phase flow line through which the gas-liquid separation device and the gas-phase
flow measurement device communicate with each other; and
a second communication line through which the gas-phase flow line and the first
5 communication line communicate with each other.
5. The drain removal monitoring equipment according to any one of claims 1 to 4,
wherein the gas-phase flow measurement device includes a plurality of measurement
mechanisms, and
10 wherein each of the plurality of measurement mechanisms includes:
a pressure gauge for measuring a pressure of the gas phase;
a critical nozzle disposed downstream of the pressure gauge; and
an opening and closing valve disposed upstream or downstream of the pressure gauge and
the critical nozzle.
15
6. The drain removal monitoring equipment according to claim 5,
wherein the critical nozzle is a Laval nozzle.
7. The drain removal monitoring equipment according to any one of claims 1 to 6,
20 wherein the gas-liquid separation device is a cyclone separator.
8. The drain removal monitoring equipment according to any one of claims 1 to 7,
wherein the liquid-phase flow measurement device includes:
a tank part for storing the liquid phase; and
25 a liquid-phase amount detection part for detecting an amount of the liquid phase in the
tank part.
9. The drain removal monitoring equipment according to claim 8,
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wherein the liquid-phase return line is connected to the tank part, and
wherein the liquid-phase return line is provided with a drainage valve configured to open
if a value detected by the liquid-phase amount detection part reaches a preset upper limit value.
5 10. The drain removal monitoring equipment according to any one of claims 1 to 9,
comprising:
a control device to which the flow rate of the liquid phase and the flow rate of the gas
phase measured by the liquid-phase flow measurement device and the gas-phase flow
measurement device are transmitted,
10 wherein the control device is preset with an upper limit value and a lower limit value for
the flow rate of the liquid phase, and an upper limit value and a lower limit value for the flow
rate of the gas phase, and
wherein the control device detects an abnormality in the drain removal based on the flow
rate of the liquid phase and the flow rate of the gas phase respectively transmitted from the
15 liquid-phase flow measurement device and the gas-phase flow measurement device, and the
upper limit value and the lower limit value for the flow rate of the liquid phase and the upper
limit value and the lower limit value for the flow rate of the gas phase