JPH0718750B2 - Foreign object detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting foreign matter in a fluid, and more particularly to a foreign matter detection apparatus suitable for detecting foreign matter in steam flowing into a steam turbine.

[Conventional technology]

A typical example of a steam turbine plant system is shown in FIG. To explain the outline of this system, the water condensed in the condenser 10 is heated in the boiler 1 to become steam. This steam flows through the main steam stop valve 2 and the regulator valve 3 into the high-pressure turbine 4 to rotate the turbine rotor and rotate a generator (not shown). The steam that worked in the high-pressure turbine 4 is again the boiler 1
Is recovered by the reheater in the boiler and is worked by the intermediate pressure turbine 8 and the low pressure turbine 9 via the combined reheat valve 5 having the reheat steam valve 6 and the intercept valve 7 built-in, and the steam is condensed. It becomes water again in vessel 10.

In this system, the main steam stop valve 2, the regulator valve 3, the reheat steam stop valve 6 and the intercept valve 7 arranged in front of each turbine casing have a function of controlling the rotational speed of the turbine and a power generation load. It is an important valve that has a safety function to stop the turbine in an emergency. Of course, these are executed by the control unit of the steam flow rate, that is, by changing the opening degree of the valve, but when the valve is opened and closed, the flow velocity of the steam rises, and solid fine particles from the boiler 1 in the steam collide with the member to cause erosion. There is. For example,
In order to relieve the thermal stress in the turbine casing at the time of starting the turbine, a full-circle injection starting in which steam is introduced from the entire periphery of the turbine casing is performed. At this time, a bypass valve may be incorporated in the main steam stop valve 2. . In this case, since the bypass valve is in a slightly opened state, steam and solid particles contained therein also flow at the speed of sound, and erosion occurs on the valve rod of the main steam stop valve, the bypass valve, and the like. In addition to the main steam stop valve, erosion similarly occurs in the steam turbine inlet nozzle. The generation of such solid fine particles cannot be completely eliminated even if various measures are taken. And, as is the case recently, when turbine daily start and stop (DSS) and weekend start and stop (WSS) are performed,
The amount of solid fine particles generated increases due to the temperature change. As measures against this solid fine particle, measures such as throwing the solid fine particle out of the system by blowing to the outside of the boiler, or applying surface treatment to the surface of the part to make it hard to be eroded are taken as a countermeasure. Not really. Also, as disclosed in Japanese Patent Publication No. 57-43789, there is a device in which the shape of the valve is devised as a measure against erosion of a main steam stop valve having a bypass valve.

[Problems to be solved by the invention]

The one disclosed in Japanese Patent Publication No. 57-43789 is effective as a countermeasure for valve rod erosion, but erosion occurs on the projection part at the tip of the bypass valve and the wall surface of the passage hole for passing steam after passing the bypass valve. However, it is not a complete erosion control measure. For this reason, it is necessary to grasp the size, amount, and distribution of the solid fine particles contained in the steam, but at the present stage, there is no such technique.

An object of the present invention is to provide a foreign matter detection device for grasping the size, amount, and distribution of solid fine particles contained in vapor.

[Means for solving problems]

The above-mentioned problem is that in a foreign matter detection device for determining the distribution of solid fine particles contained in a fluid flowing in a pipe, a sound stick inserted in a direction traversing the pipe, and the sound stick attached to both ends of the sound stick. First and second AE sensors for detecting sound generated when solid particles collide with the rod, and the first and second AE sensors
Signal processing means for obtaining the collision position of the solid fine particles from the difference between the detection signals of the sensor and for obtaining the distribution of the solid fine particles in the transverse direction of the pipe from the detection signal detected when the listening rod is moved in the insertion direction. It is achieved by providing.

[Action]

The amplitude and frequency spectrum of the output of the AE sensor change depending on the amount and size of solid particles flowing in the tube.
Therefore, AE for various values of amount and size of solid particles
If the amplitude of the sensor output and the characteristics of the frequency spectrum are measured in advance, the size and amount of the solid fine particles in the tube can be constantly monitored by comparison with them.

If AE sensors are provided at both ends of the listening rod, the collision position of the solid particles can be obtained from the difference between the detection signals. Therefore, the distribution in the transverse direction of the pipe can be obtained by obtaining the position of the solid fine particles that collide with each other while inserting the listening rod into the pipe.

〔Example〕

An embodiment of the present invention is shown in FIGS. FIG. 3 is a diagram showing a state in which a sound stick 14 for detecting the collision sound of solid particles is inserted in the steam pipe. There is a sound-sensing part 13 in the center of the listening rod 14, and when the vapor containing the solid particles 11 flows from the left to the right in the steam pipe 12, the sound-sensing part produces the sound generated when the solid particles collide. It is detected and received by the AE sensor 15.

FIG. 1 shows an embodiment of the processing system and the recording / display system of the AA cross section of the steam pipe 12 and the output of the AE sensor 15 in FIG. 3, and the collision sound signal detected by the AE sensor 15 is shown. Is amplified by a preamplifier 16 and is amplified by a main amplifier 18 through a noise filter 17 for separating noise of vapor flow. Furthermore, this output is averaged by the averaging circuit 19 and the pen recorder
Recorded at 20. On the other hand, a part of the signal passed through the main amplifier 18 is passed through a filter 21 through which the frequency component of the collision signal passes, and then input to a signal analysis device 22. The device 22 is inputted with a pre-determined discrimination waveform 23 for discriminating the amount of the solid fine particles 11 and the size of the particles, which is displayed on the monitor 24 together with the detection waveform and recorded on the recorder 25. Be monitored.

Waveforms a and b in FIG. 4 show a small amount of solid fine particles in the sound sensing part 13.
The output of the main amplifier 18 is shown when the solid particles 11 collide with each other and when a large amount of the solid particles 11 collide with each other, and a difference in amplitude occurs due to a difference in velocity energy of the solid particles. Therefore, from the averaged value of this, that is, the recording of the pen recorder 20,
The amount of solid particles can be determined. Further, when the frequency analysis at this time is performed by the device 22, the difference in the amplitude and the waveform density appears as shown by the waveforms c and d in FIG. This waveform is the discrimination waveform
By comparing with 23, it is possible to judge the amount of solid fine particles to some extent. Further, since the sound sensing unit 13 senses only a collision of a part of the steam pipe cross section, the amount of solid particles in the steam pipe 12 is determined from the area of the sound sensing unit 13 and the cross sectional area of the steam pipe 12. Can be estimated. Regarding the size of solid particles, the detection waveform when the particles are small (main amplifier output)
And the frequency analysis output becomes the waveforms a and c in FIG. 4, and becomes the waveforms b and d when the particles are large. Therefore, the discrimination waveform 23
By comparing with the above, it becomes possible to quantitatively judge the state of the solid particles of the actual machine.

FIG. 5 shows another embodiment of the present invention. The difference from FIG. 1 is that the sound sensing portion 13 can be moved on the listening stick 14, and that the AE sensors are provided at both ends of the listening stick 14. 15A and 15B are attached, and the signals from each sensor are sent to the preamplifier 16A, 16B, noise filter 17A, 17B, main amplifier 18A, 18B, average value circuit 19
The point is that it is configured to pass A and 19B. According to this embodiment,
As shown in FIG. 6, the frequency analysis result by the analysis device 22 shows that the AE sensor (15A in FIG. 5) side close to the sound sensing unit 13 and the AE sensor (15B in FIG. 5) side far from the sound sensing unit 13 There is a difference Δx between them. This difference will indicate the position within the steam pipe 12. By appropriately moving the sound-sensing part 13 of the listening rod 14, it becomes possible to grasp the distribution of the solid fine particles 11 in the steam pipe.

〔The invention's effect〕

According to the present invention, the amount of solid fine particles contained in the steam flow and the size and distribution of the particles can be constantly monitored, so that the erosion of the steam turbine can be prevented in advance, and especially the DDS and W of the turbine can be prevented.
It has a great effect when SS is performed.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of the present invention, FIG. 2 is a view showing a steam system of a steam turbine, FIG. 3 is a view showing a mounting state of a hearing rod to a steam pipe, and FIG. The figure which shows the detection waveform of the Example of FIG. 5, FIG. 5 is the figure which shows another Example of this invention,
FIG. 6 is a diagram showing a frequency analysis waveform of the embodiment shown in FIG. 11 …… Solid fine particles, 12 …… Steam pipe, 13 …… Sound-sensing part, 14…
… Listening bar, 15,15A, 15B …… AE sensor, 16,16A, 16B ……
Preamplifier, 17,17A, 17B …… Noise filter, 18,18A, 1
8B …… Main amplifier, 19,19A, 19B …… Averaging circuit, 20 ……
Pen recorder, 21 …… Frequency filter, 22 …… Analysis device, 23 …… Discriminant waveform, 24 …… Monitor, 25 …… Data recorder.

Claims (1)

[Claims] 1. A foreign matter detection device for determining the size, amount, and distribution of solid fine particles contained in a fluid flowing in a pipe, wherein a sound rod inserted in a direction traversing the pipe and both ends of the sound rod. A first and a second AE sensor for detecting a sound generated when solid fine particles collide with the attached sound-accepting rod;
When the size and amount of the solid fine particles are obtained from the detection signals of the first and second AE sensors, the collision position of the solid fine particles is obtained from the difference between the detection signals of both AE sensors, and the sound stick is moved in the insertion direction. And a signal processing means for obtaining a distribution of solid particles in the transverse direction of the pipe from detection signals detected by both AE sensors.