JPH01302132A - Apparatus for detecting valve seat leak - Google Patents

Abstract

PURPOSE:To prevent the outputting of an unnecessary alarm signal at the time of the low load of a plant, by inputting the open state of an objective valve or an equivalent state signal to a detector and judging that a valve seat leak detection result is proper. CONSTITUTION:In such a state that no valve seat leak is generated, a no-leak signal is generated from the first signal judge part 6 and, therefore, the AND of an AND circuit 13 is not formed. When a leak is generated in a valve seat, the condition of the AND circuit 13 is formed. By this mechanism, the alarm lamp 7a of a display part 7 flashes to inform the generation of the leak and a diagnostic result display part 7b displays estimated leak quantity. When it is assumed that the load of a power plant falls and a drain valve 1 is opened, a limit switch 15 emits an OFF signal, that is, a valve open signal and, therefore, an actual open degree condition judge part 8 also shows a valve open state to form the AND of the AND circuit 13. Therefore, a condition switch 14 is automatically turned OFF and the display part 7 offers no erroneous data of leak presence.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is a one-valve seat leak detection device that detects the presence or absence of leakage by measuring the noise generated when fluid leaks from the valve seat portion. Regarding.

(Prior Art) Thermal power plants, nuclear power plants, and the like are equipped with a large number of various valves for process control, isolation, and the like.

Among these valves, for example, the drain valves in the main steam system or oil/gas system, which are high-temperature, high-pressure steam systems, are fully opened at startup to discharge drain from the steam piping line up to approximately 5 to 15% load. However, during normal operation, no condensate is generated and it is fully open to prevent unnecessary loss of steam thermal energy.

However, while these valves are used for a long period of time, they may become damaged due to erosion of the valve seat portion or foreign objects caught during opening/closing operations, resulting in leakage. Once a leak occurs, the high-speed steam flow tends to quickly enlarge the flaw and cause even more leakage.
Early detection of valve leaks has become an important research topic from the standpoint of thermal efficiency and maintenance management.

Recently, acoustic emission (ac
A lot of research is being conducted on detecting leaks when the valve is fully open and detecting erroneous operations when the valve is fully closed using the AE sensor (hereinafter referred to as AE sensor) (for example, Japanese Patent Laid-Open No. 132-198). 80535
(see issue).

Figure 3 shows an example of the configuration of a valve seat leak detection device using an AE sensor currently being considered for boat fishing.
Reference numeral 1 indicates a target valve whose leak is to be detected, 2 a working fluid such as steam or water, 3 an AE sensor, 4 an amplifier, 5 a signal processing section, 6 a signal judgment section, and 7 a display section.

In a valve seat leak detection device with such a configuration, if a leak occurs in the working fluid 2 when the valve 1 is fully open, a flow sound of the working fluid, cavitation noise, or vibration of the piping, valve, etc. due to the flow will occur. However, these sounds and vibrations are multiplied by the AE signal and detected by the AE sensor 3.

Although this signal is continuous, the signal level is low, so
After being amplified by the amplifier 4, the signal is input to the signal processing section 5. As a processing method in the signal processing section 5, a method of calculating an effective value, a method of frequency analysis using a spectrum analyzer, etc. are common.

The signal from the signal processing section 5 is output to the signal determining section 6.

In this judgment section, the signal from the signal processing section 5 is compared with the effective value level when no leak occurs from the valve, or a threshold value with a predetermined margin in the frequency analysis result, and the signal is detected. When the signal level exceeds this threshold,
It is determined that a leak has occurred.

In addition, the display unit 7 flashes the warning light 7a, displays the effective value or frequency analysis value that is the basis of the diagnosis result, and displays the estimated leakage amount.

(Problem to be Solved by the Invention) In such a valve seat leak detection device, there is no particular problem in monitoring leaks during normal operation, that is, when the valve is fully open. As mentioned above, valves that automatically operate when the load decreases have the following problems.

■ When the load drops and the drain valve opens, the valve seat leak detection device will indicate the occurrence of a leak, but the operator must consider the drain valve opening interlock conditions such as the load and determine whether this leak is the original valve seat leak. It is necessary to determine whether this is due to the occurrence of the problem or whether it is caused by the drain valve automatically engaging.

■ - The load that opens the drain valve in boat fishing is 5 to 15% load, but this load varies depending on the drain valve, so operators must have a good understanding of the many drain valves and their 6F conditions. .

In particular, recent thermal power plants are operated for load adjustment, and DSS (Daily 5tart 5
Top) driving or late-night minimum negative 4J driving is occurring frequently, so it is thought that such improvements will receive more and more attention in the future, and some measures are necessary to reduce the burden on operators. .

The present invention provides a drain valve equipped with a valve seat leak detection device using an AE sensor, and when the drain valve is operated under a load such that the drain valve automatically engages, the valve seat leak detection device is automatically connected to the drain valve. The object of the present invention is to provide a valve seat leak detection device that does not give false information to operators.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention uses a signal from the determination section of the valve seat leak detection device, a plant load signal, a valve opening request signal, or an actual valve The present invention is characterized in that a second signal determining section that inputs the opening degree signal is newly provided, and the information is provided to the plant operator only during the valid period of valve seat leak detection.

(Example) ψ Hereinafter, the present invention will be described in detail with reference to the drawings. In addition,
In FIGS. 1 and 2, the same elements as in the prior art are given the same reference numerals.

In FIG. 1, the second signal determination unit 8 detects the detection target valve 1.
actual opening condition determination section 9, opening requirement determination section 10, load condition determination section 11, OR circuit 12, and AND circuit 13.
Furthermore, a condition switch 14 is provided between the signal judgment section (first signal judgment section) 6 and the display section 7, which is activated when the condition of the AND circuit 13 is satisfied.

In the valve seat leak detection device having such a configuration, the information on the presence or absence of a leak from the first signal determining section 6 is output in the same way as in the prior art, but instead of being directly input to the display section 7, The signal is inputted to the signal determining section 8 of.

In addition to the information on the presence or absence of leakage from the first signal determining unit 6, the second signal determining unit 8 also includes a limit switch 15 for detecting a closed position indicating the actual opening state of the valve 1 to be detected, or a differential A signal 16 from an actual opening detector such as a transformer, an opening request signal 17 for the valve 1 to be detected, and a load signal 18 are input.

These signals 16 to 18 all represent the valve opening state, and a signal is issued to the AND circuit 13 only when the valve is fully open. Therefore, it is not necessarily necessary to have a plurality of signals indicating the valve opening state, but one signal that is easy to use in practice.
Even one is enough.

For example, if the target valve does not have an actual opening detector, or if there is an opening request signal but there is a risk that using this signal will cause a disturbance in plant control, or if the valve is not equipped with a valve seat leak detection device. If the distance between the two terminals is too large and the wiring work is difficult or economically problematic, the load signal 18 may be used as a representative.

The output of the OR circuit 12 which receives the signals from the determination units 9 to 11 is input to the AND circuit 13 together with the signal from the first signal determination unit 6.

When the signal determining unit 6 of the il determines that a leak has occurred, and the logical sum circuit 12 determines that the valve is fully closed, the logical product 13 is established, the condition switch 14 is activated, and the valve is closed. The seat leak occurrence display section and the first signal determination section are connected to display the occurrence of valve seat leak.

Next, an example in which the valve seat leak detection device of the present invention having the above configuration is applied to an actual plant will be described. It is assumed that the valve opening state of the valve to be detected is grasped by the limit switch 15.

During rated load operation of the plant, valve 1, which is subject to valve seat leak detection, is fully open, and limit switch 1
The signal from 5 is manually input to the actual opening condition determination section 9. Here, since a valve fully open state signal is generated, AND circuit 1
This means that one of the conditions 3 is satisfied.

When no valve seat leak occurs, the first signal determining section 6 issues a signal indicating that there is no leak, so the AND of the AND circuit 13 does not hold. If a leak occurs in the valve seat, a signal indicating that there is a leak is issued from the first signal determining section 6, and the condition of the AND circuit 13 is satisfied. As a result, the condition switch 14 is turned on. As a result, the warning light 7a of the display section 7 flashes to notify the user of the occurrence of a leak, and the diagnostic result display section displays the estimated leakage amount and the like.

If the load of the power plant decreases and, for example, the drain valve 1 opens at 10% load, in the conventional technology there is no part to judge this state, so a leak is displayed, but in the present invention, the drain valve 1 opens when the load is 10% 15 is OFF
In order to issue a signal, that is, a valve open signal, the actual opening condition determination unit 8 also indicates the valve open state, and the logical product 13 is established. Therefore, the condition switch 14 automatically switches to 6FFL, and the display unit 7 does not provide erroneous information indicating that there is a leak. Therefore, unnecessary confusion will not be caused to the operator.

FIG. 2 shows another embodiment of the present invention, in which a load signal is used as the valve opening state determination signal. In the figure, the signal from the AE sensor (not shown) is transmitted to amplifier 4.
signal selector 20 via a s, 4 b s 4 c
The signals are input to the signal processing section 5 and the first signal determining section 6 and then manually inputted to the signal aggregation section 21 . Further, the outputs from the first signal determining section 6 and the load condition determining section 11 are AND circuits 13a and 13b.

The signal is input to the signal aggregation unit 19 through 13c.

As described above, the advantages of using the load signal for determining the valve opening state are as follows.

In a power generation plant, it is rare for a valve seat leak detection device to target only one drain valve, and for boat fishing, it is customary to target several to several valves. All of these valves are fully open under a predetermined load, but for example, if a signal from a limit switch is used as a signal indicating the valve opening status, the input signal to the valve seat leak detection device will also be this signal. It will increase proportionately.

Drain valves are installed at the power plant site, whereas valve seat leak detection devices are generally installed in the central control room, and in order to extract the limit switch signal, the valve seat leak detection device is generally installed in the central control room. Connecting with cables requires a lot of effort and expense.

Furthermore, even if it is possible to extract signals from limit switches, etc. from a panel in the central control room via cables, the cable core wires must be at least as long as the number of valves to be detected, making the system quite complex. becomes.

However, when the load signal 18 is input as shown in Fig. 2, this signal is the only signal manually input to the second judgment section, and even if a large number of valves are connected, the system can be operated without being affected by them. Can be built.

Valve opening condition determination for multiple valves is performed by the load condition determining section 11. In other words, the load condition determination unit 11 determines that the load is α
1 or more, the drain valve should be fully open conditionally, and if valve seat leakage has occurred, the AE doubler signal amplifier 4A1 signal selector 20, signal processing unit 5
The signal is inputted to the judgment section 6 via the signal, and a signal is thereby generated, and the AND condition of the AND circuit 13A is satisfied.

As a result, the signal collection section 19 turns on the condition switch 14 to display the occurrence of valve seat leak.

Similarly, when the load exceeds α2 or α3, each drain valve is conditionally fully opened, and the output signal from the AE sensor detects valve seat leakage. Conversely, when the load is less than α1, α2, α3, the output signal level from the AE sensor is considered to indicate that there is a valve seat leak, but since the valve opening condition is not satisfied, the valve seat leak detection device as a whole considers it to be outside the scope of judgment. It means not providing any extra information.

As described above, according to this embodiment, the opening state of the drain valve can be represented by one representative signal, for example, the load signal, regardless of the number of drain valves, and the system can be simplified. can.

[Effects of the Invention] As explained above, according to the present invention, in a valve seat leak detection device for a control valve such as a drain valve in a power generation plant, the opening state of a target valve is detected by this detection device. Alternatively, by inputting a corresponding status signal and determining that the valve seat leak detection result is appropriate, it is possible to prevent the output of unnecessary alarm signals during low load of the plant.

Therefore, the power plant operator can concentrate on the very complicated and delicate operation during startup without being confused by the erroneous signal from the valve seat leak detection device.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an embodiment of the valve seat leak detection device according to the present invention, Fig. 2 is a system diagram showing an embodiment in which a signal representative of the valve opening state is used as a plant load signal, and Fig. 3 is a system diagram showing an embodiment of the valve seat leak detection device according to the present invention. FIG. 2 is a system diagram of a conventional valve seat leak detection device. 1... Valve 2... Working fluid 3... AE sensor 4.4A, 4b, 4.C... Amplifier 5. ......Signal processing section 6...Signal judgment section (first signal judgment section)
7...Display section 8...Second signal judgment section 9...
. . . Actual opening condition determination section 10 . . . Opening requirement determination section 11 . . . Load condition determination section 1
2......OR circuits 13A, 13B, 13C...AND circuits 14...
...Condition switch 15...Limit switch 16-18.
...Signal 19.21...Signal aggregation section 20...Signal selector

Claims (1)

[Claims] In a valve seat leak detection device consisting of an acoustic emission sensor, an amplifier, a signal processing section, a first signal judgment section, and a display section, in order to check the opening state of the valve, 1. A valve seat leak detection device comprising: a second judgment unit incorporating an AND circuit that satisfies an AND condition using a signal representing a state of the valve seat and a signal from the first judgment unit.