JPS6244083B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a turbine valve diagnostic device that automatically diagnoses the operating state of an on-off valve for high-temperature fluid in a steam turbine, gas turbine, or the like.

In a steam turbine, main steam on-off valves such as a main steam stop valve, a reheat steam stop valve, and an intercept valve are important components and are required to have a high degree of reliability. Therefore, it is important to continue monitoring these valves while the steam turbine is in operation to detect signs of failure early.

FIG. 1 shows an example of the main steam stop valve, in which a strainer 3 is placed inside a main valve casing 1 equipped with an upper lid 2.
and a valve seat 5 are provided. The valve body 4 is the valve stem 6
The valve stem 6 is connected to the bush 8.
By being slidably supported by a, 8b, and 8c, it is structured so that it can be opened and closed in close contact with the valve seat 5 and can be moved away from the valve seat 5. 7 is a housing.
The driving part of the valve body 4 is a hydraulic actuator 9,
It consists of a hydraulic cylinder 10, a piston 11 and its piston rod 12. 11a is a piston ring, and 8d is a bush. The valve stem 6 and the piston rod 12 are connected by a coupling 13. And the compression spring 14 is the piston 1
1 is biased downward.

Stakes are one of the serious failures in valve devices having the structure described above. This failure occurs when a proper gap cannot be maintained between the valve stem 6 and the bushes 8a to 8c, resulting in seizure, jamming, etc., resulting in the inability to slide. There are many reasons why a proper gap cannot be maintained, such as scale formation, intrusion of foreign matter, bending of the valve stem 6, and misalignment of the coupling 13. Stakes do not occur suddenly; in many cases, abnormalities such as poor sliding, chatter, and chattering occur, which gradually expand and lead to stagnation. Therefore, in order to prevent stuck valves, it is extremely important to detect these minor abnormalities in valve operation at an early stage and take appropriate measures at an early stage.

Inspections of the main steam valves of turbines at power plants, etc. are normally carried out once a day by operating the valves from fully open to fully closed and from fully closed to fully open using a manual test device as shown in Figure 2 below. A staff member visually checks its operating condition. In Fig. 2, hydraulic cylinder 1
The upper chamber of the piston 0 is constantly communicated with an oil tank 16 via a drain circuit 15. When the control oil 17 is injected into the piston lower chamber of the hydraulic cylinder 10, the piston 11 resists the biasing force of the compression spring 14.
Push up to open the valve body 4. When the supply of the control oil 17 is cut off, the piston 11 is lowered by the biasing force of the compression spring 14, and the valve body 4 is closed. Reference numeral 89 is a relay dump valve for emergency closing in an emergency situation, and during normal operation, it is pushed up by the emergency shutoff oil 18 and closed. When the supply of emergency shutoff oil 18 is cut off, the relay dump valve 8
9 is opened, the piston lower chamber of the hydraulic cylinder 10 is communicated with the oil tank 16, and the valve body 4 is urgently closed.

To perform the once-daily valve actuation test described above, test equipment switch 48 is closed. Then, the test device solenoid valve 91 is opened and the compressed air 19 flows into the piston lower chamber of the air cylinder 96, and the lever 20
is moved to raise the test pilot valve 90 and shut off the control oil 17. As a result, the piston of the hydraulic cylinder 10 descends, and the valve body 4 closes. Next, when the switch 48 is opened, the valve body 4 is opened by the opposite action to that described above. An operator visually inspects the valve closing and opening operations described above to determine whether there is any abnormality.

However, although the testing methods described above can detect abnormalities in valve operation that can be detected with the eyes and ears,
Minor signs of failure are difficult to detect even by experienced workers.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a device that can sensitively and accurately diagnose the presence or absence of signs of minor failures in a turbine on-off valve device.

In order to achieve the above object, the present invention provides a sensor that detects the pressure of the driving medium that drives the valve body, and also provides sensors that detect the stroke of the valve body or whether the valve body is fully open or fully closed, and
The present invention is characterized in that an arithmetic processing device is provided that automatically processes electrical signals generated by each of the sensors and determines whether or not there is an abnormality in the opening/closing operation of the valve body.

Next, one embodiment of the present invention will be described with reference to FIGS. 2 to 6. As shown in FIG. 2, a pressure sensor 70 for detecting oil pressure is attached to the hydraulic cylinder 10, and a position sensor 92 is attached via a lever device 21 to the coupling 13 that connects the valve stem 6 and the piston rod 12. Let the movement of 4 be detected. Further, a limit switch 51 for detecting the fully open position of the valve body 4 and a limit switch 52 for detecting the fully closed position are provided.

FIG. 3 shows the configuration of the hardware system of this embodiment. The output signals of the fully open valve detection limit switch 51, the fully closed valve detection limit switch 52, and the operating switch 48 of this test device are input to the digital input circuit 41. Said hydraulic cylinder 1
0 oil pressure is detected by the pressure sensor 70 and converted into a voltage signal or current signal corresponding to the oil pressure by the signal converter 71, and the mechanical movement of the position sensor 92 is converted into a valve stroke by the signal converter 55. The signal is converted into a corresponding voltage signal or current signal and input into the analog input circuit 40, respectively. These are processed by a microcomputer 42, and the results are displayed on a display lamp 45 via a digital output circuit 44, as well as a printer 46 or a CRT display device 4.
7 to output. Further, past data is stored in the external storage device 43 and read out as needed.

Next, the configuration of the arithmetic processing unit of the diagnostic device of this embodiment will be explained with reference to FIG. The mechanical movement of the position sensor 92 that detects the opening/closing position of the valve is input to the signal converter 55, and the oil pressure of the hydraulic cylinder is input from the pressure sensor 70 to the signal converter 71, and the signal converter 55, 71 inputs the hydraulic pressure of the hydraulic cylinder to the signal converter 71. The signal is then converted into a voltage signal or a current signal. This signal output is configured to be input to the data storage 56 via a switch 51a which is opened and closed by a fully open detection limit switch 51 and a fully closed detection limit switch 52. The switch 51a described above is closed when both limit switches 51 and 52 are opened, and opened when either one is closed. The oil pressure signal is input from signal converter 71 to data storage 56 and the stroke signal is input from signal converter 55 to stroke synchronizer 60. The stroke synchronizer 60 outputs a signal to the timing controller 57 every time the actually measured stroke signal reaches a hydraulic signal sampling stroke at a fixed interval, and the timing signal is input to the data storage 56 in accordance with this signal. That is, the data storage 56 stores measured oil pressure values at each constant stroke interval. The data storage device 56 inputs the stored electrical signal data to the deviation calculator 63, and the reference value calculator 61 calculates a reference oil pressure value at regular stroke intervals, and inputs the result to the reference value storage device 62. At the same time, its output is input to the deviation calculator 63. Then, the deviation calculator 63 compares the two and calculates the deviation.

The present example is configured to have a function of storing a reference value as described above, and to be able to calculate a deviation by comparing electrical signals input from each sensor with the reference value. As will be described in detail later, the present invention is characterized in that the previous measurement data is stored and the deviation of the next measurement data is calculated using this as a reference value.

A deviation reference value 65 is provided separately from the above-described configuration, and a deviation comparator 64 is provided which compares and calculates the deviation reference value stored in this storage device with the deviation value calculated by the above-mentioned deviation calculator 63. A deviation determiner 66 is provided which determines whether or not there is an abnormality in valve operation based on the comparison result.

As described above, this example is configured to have a function of storing the deviation reference value and a function of comparing and determining the calculated deviation value with the above deviation reference value.

The output signal of the deviation determiner 66 is input to a display device 67 that displays the determination result of the deviation determiner 66.

This embodiment is configured as described above. Next, its operation will be explained. When the switch 48 of the test device shown in FIG. 2 is closed, the valve body 4
When the switch 48 is opened, the valve body 4 is opened. When the valve body 4 begins to close, a fully open detection limit switch 51 opens, and when the valve body 4 finishes closing, a fully closed detection limit switch 52 closes. During the valve closing operation, the position sensor 92 moves according to the valve body 4.

(See FIG. 4) When the full-open detection limit switch 51 opens in the above-described operation, the switch 51a linked thereto closes, and an electrical signal representing the valve position generated by the signal converter 55 is sent to the stroke synchronizer 60. Further, a pressure signal of the hydraulic cylinder corresponding to this valve position is sent as an electrical signal to the data storage device 56 by the signal converter 71. Data storage 56 has a limited capacity and must be sampled at regular intervals. Accordingly, recording signals are transmitted to data storage 56 at regular stroke intervals. That is, when the actual stroke value reaches a certain oil pressure sampling stroke value by the stroke synchronizer 60, the storage timing signal is transmitted to the timing controller 57.
The timing controller 57 sends the signal to the data storage 56. In this manner, the oil pressure signal is stored in the data storage 56 at regular stroke intervals until the valve goes from fully open to fully closed. Then, the fully closed detection limit switch 52
When turned ON, the oil pressure signal is cut off and the data storage 56
Recording will be stopped. An example of stored data is shown in FIG. In this figure, the horizontal axis shows the valve closing stroke (unit: %), and the vertical axis shows the amount of oil pressure fluctuation of the hydraulic cylinder that drives the valve body (unit: Kg/cm2 ^).
g). The solid line at 21 is the hydraulic pressure curve of the actual value stored during the valve closing direction test. Actual measurement value 21 is shown as a continuous line, but it is made up of a series of points because it is sampled at regular stroke intervals. A reference characteristic is calculated by the reference value calculator 61 at each constant stroke interval. Among the reference characteristics, parts where oil pressure fluctuations are large and there is a possibility of misjudgment are ignored, and reference values for other parts are calculated using the following calculation function.

g(x)=a+b・X+c・X ² +d・X ³ +e・X ⁴ +f・X ⁵ ...(1) where g(x): Hydraulic reference value function (Kg/cm ²・g) a, b: Coefficient Next, the deviation calculator 63 calculates the deviation between the actual measurement value 21 and the reference value 22. That is, Δ(x)=f(x)−g(x) where Δ(x): deviation function f(x): measured oil pressure function g(x): reference oil pressure function This is shown in FIG. The horizontal axis of this figure shows the valve closing stroke (unit: %) of the valve body, and the vertical axis shows the hydraulic pressure deviation (unit: %) of the hydraulic cylinder that drives the valve body, with zero as the center. The upper side is positive deviation, and the lower side is negative deviation. The deviation value ±10% is set as the step symptom point, and the deviation value ±20% is set as the alarm point. These control points can be set as appropriate based on empirical data. In example 23, the deviation value characteristic is almost the same as on the horizontal axis of 10%, and it is judged that the operating state is almost normal. In example 24, the deviation value does not exceed the alarm point, but it exceeds the step sign point, and it is determined that a sign of an abnormality has appeared. In example 25, the deviation value exceeds the alarm point, and although the stick has not yet stuck, it is determined that the stick is in imminent danger.

In this example, the deviation reference value 65 shown in FIG.
Store the reference values of 10% of the stagnation symptom and 20% of the stagnation alarm point in the memory.
Standard value calculated by deviation calculator 63 (10%, 20%)
The deviation comparator 64 compares the valve operation status with the deviation comparator 64, and the valve operating status is classified into three categories: normal status (10%>), symptom present (10% to 20%), and dangerous status (20%<). It is determined whether the state is in one of the categories, and the result is displayed on the display device 67.

In this embodiment, the case is shown in which the valve is fully open to fully closed, but the stuck sign determination can be similarly performed in the case where the valve is fully closed to fully open. In this case, a symptom appears as a negative deviation.

The comparison calculation device of this example has the function of storing the deviation reference value as described above and the function of comparing the calculated deviation value with the above reference value and making a judgment. The presence or absence of an abnormality in the valve operating state can be automatically determined without the need for.

As in this example, equipment that has the function of displaying the above judgment results (for example, an alarm lamp,
By providing an alarm buzzer, printer, etc.), it is possible to quickly and easily detect signs of abnormality without requiring special skill or mental burden on the worker.

Next, another embodiment of the present invention is shown in FIGS. 7 and 8. As shown in FIG. 5, when there is a sign of stagnation, the rate of change in pressure becomes large, so determination can also be made by determining and monitoring the rate of change in pressure. Figure 7 shows a fully open detection limit switch 51 and a fully closed valve detection limit switch 5.
2 detects the start of movement of the valve and then detects whether the valve is fully open or fully closed. After storing pressure data in the data storage 56, the rate of change of the pressure value is calculated by the rate of change calculator 80, This result is stored in the rate of change storage 81. Thereafter, the stored rate of change and the rate of change reference value 82 are input to the rate of change comparator 83.
The result is determined by the change rate determiner 84, and this result is displayed on the display device 67.

Further, signs of stagnation can also be determined by monitoring the characteristics of pressure with respect to time as shown in FIG. That is, the signal from the pressure sensor 70 is input to the signal converter 71, and the signal from the signal converter 71 is opened and closed by the fully open detection limit switch 51 and the fully closed detection limit switch 52. When closed, the valve stroke signal is input to data store 56 while simultaneously sending a time signal from timer 54 to timing controller 57 . Upon receiving this time signal, timing controller 57 causes data storage 56 to periodically store the input signal at appropriate time intervals. Furthermore, the time signal from the timer 54 is opened and closed by the fully open detection limit switch 51 and the fully closed detection limit switch 52 in the same way as the signal from the pressure transducer 71, and the full stroke time measuring device 5
8 and the result is stored in the total stroke time storage 59. The stored signal is input to a reference value calculator 61 to calculate a reference valve stroke time value, the result is input to a reference value store 62, and its output is input to a deviation calculator 63. The deviation calculator 63 compares the actual valve stroke time value from the data storage 56 with the reference valve stroke time from the reference value storage 62 to calculate a deviation. Thereafter, the deviation comparator 64 compares the reference value calculated by the deviation calculator 63 with the reference value of the deviation reference value 65, the deviation determiner 66 judges the valve operating state, and the result is displayed on the display device 67. indicate.

As described above, according to the present invention, it is possible to sensitively and accurately diagnose the presence or absence of a sign of a minor failure in a turbine on-off valve device.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of the main steam valve of a steam turbine, Fig. 2 is an operation system diagram in which a sensor according to an embodiment of the present invention is attached to the above-mentioned main steam valve, and Fig. 3 is an embodiment of the present invention. A block diagram showing the hardware configuration in the example, Fig. 4 is a diagram of its operation system, Fig. 5 is a diagram of the stroke characteristics of the main valves of the steam turbine,
FIG. 6 is a chart showing changes in stroke characteristics due to the occurrence of stakes, and FIGS. 7 and 8 are operation system diagrams showing other embodiments of the present invention. 4... Valve body, 6... Valve stem, 40... Analog input circuit, 41... Digital input circuit, 45...
... Display lamp, 51 ... Fully open detection limit switch, 52 ... Limit switch, 55 ... Signal converter, 56 ... Data storage device, 62 ... Reference value storage device, 63 ... Deviation calculator, 64 ... Deviation comparison device, 65...deviation reference value, 66...deviation judger,
67... Display device, 70... Pressure sensor, 71...
...Signal converter, 92...Position sensor.

Claims (1)

[Scope of Claims] 1. A diagnostic device for a turbine valve driven by an actuator including a cylinder and a piston, which includes a sensor that detects the pressure of a driving medium that drives the piston, and a sensor that detects the stroke of the turbine valve. a sensor that detects whether the turbine valve is fully closed or fully open; a test switch that supplies a driving medium to the actuator to move the turbine valve from fully closed to fully open when diagnosing the turbine valve; Capturing electrical signals,
The present invention is characterized by being provided with an arithmetic processing device that obtains a stroke characteristic representing the relationship between the stroke of the turbine valve and the pressure of the driving medium, and determines whether or not there is an abnormality in the turbine valve based on the deviation from a reference stroke characteristic given in advance. Turbine valve diagnostic equipment. 2. The turbine valve diagnostic device according to claim 1, wherein the arithmetic processing device has a function of storing the electrical signal generated by the pressure sensor at every fixed valve stroke interval. 3. The arithmetic processing device has a function of storing a reference value characteristic of driving medium pressure with respect to a turbine valve stroke, and a function of calculating a deviation by comparing this standard characteristic value with an actual measured characteristic value of driving medium pressure. A turbine valve diagnostic device according to claim 1 or 2, characterized in that the turbine valve diagnostic device has: