JP2846267B2 - Boiler pressure blast detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting pressure blast of a commercial or industrial boiler.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIGS. In FIG. 6, a boiler body 0 having a plurality of burners is provided.
A sound wave detector 03 such as a microphone is attached to the furnace wall 1 via an acoustic tube 02. The output of the sound wave detector 03 is an amplifier 04, a gate circuit 08, a high-pass filter 05,
The signal is sent to the monitoring device 07 through the detection rectifier 06, the offset correction circuit 27, and the gain correction circuit 28 in order. 09 in the figure
Is a gate signal device. 29 is a correction command device.

In the above, the output voltage from the sound wave detector 03 is amplified by the voltage amplifier 04 to an appropriate voltage. FIG. 8 shows the frequency characteristics of this output. This signal passes through a gate circuit 08, and a low-frequency component below a certain frequency (for example, 2 KHz) is cut off by a high-pass filter 05.
The output of the high-pass filter 05 is detected and smoothed by the detection rectifier 06. The monitoring device 07 receives the output of the detection rectifier 06 that has been subjected to offset correction and gain correction based on the signal of the correction command device 29, monitors the detection status, records and displays the output, and outputs the output at or above the set level. Sometimes an alarm is issued.

[0004] The gate signal 09 gives a close signal to the gate circuit 08 only during the time of controlling the boiler's suit blow, and blocks the passage of the signal. This is because a high frequency sound is emitted during a suit blow operation, which makes it difficult to identify an abnormal sound.

[0005] An output example of the detection rectifier 06 is shown as signals a and b in FIG. The left half of the figure shows a low level output when there is no abnormality in the boiler 01, that is, at a normal sound wave level (background noise level) during boiler operation. The right half is boiler 0
In the state where the pressure section 1 is abnormal for some reason, that is, blasting occurs, and water or steam is ejected from the injection hole at the sonic speed, the output becomes higher than the background noise level.

[0006] After the output of the detection rectifier 06 is subjected to offset correction or the like, the output is monitored by a monitoring device 07, and an alarm is issued when the output level exceeds a set level. Incidentally, the characteristics of the background noise level in the boiler differ depending on the boiler load and the mounting position of the detector (for example, near or far from the burner). Further, depending on the position of the detector, a high-frequency component may be present in the background noise level, and the accuracy of discriminating the background noise level from the abnormal sound level due to blasting or the like is poor, and there is a possibility of erroneous detection.

Further, when the level difference between the background noise and the abnormal sound is small, it is difficult to detect (d signal in FIG. 10).

As described above, in order to eliminate the difference due to the boiler load or the occurrence level of the abnormal sound at the sensor position,
The background noise level of each sensor with respect to the load of the boiler is experimentally detected in advance and input to the correction command device 29 and stored. Then, the correction command device 29 receives the load signal 10s and sends an offset level signal 11s corresponding to the load signal to the correction circuit 27 as shown in FIG. The correction circuit 27 corrects the output of the detection and rectification circuit 06 according to the input, removes the background noise, and outputs the result. Also, as the load increases, the level difference between the background noise and the abnormal sound becomes smaller. In consideration of this, the gain correction value of each sensor with respect to the load is experimentally set in advance and input and stored in the correction command device 29 in order to facilitate the detectability. And the correction command device 29
Receives the load signal 10s and converts the gain level signal 12s corresponding to the load signal to the correction circuit 28 as shown in FIG.
Send to The correction circuit 28 corrects the output of the correction circuit 27 in accordance with the input, and outputs the abnormal sound level easily.

The monitoring device 07 monitors this signal and issues an alarm when the level is equal to or higher than the set value.

As described above, even if the condition of the boiler load changes, the blast abnormality can be reliably detected. Furthermore, the inherent difference of the sensor mounting position can be removed, and the abnormality can be detected more reliably.

[0011]

In the above-mentioned conventional apparatus, there is a possibility that the detection accuracy may be reduced due to the accumulation of scattered materials (ash, slag, etc.) in the furnace at the opening of the acoustic tube.

[0012] In addition, during long-term use, there is a risk of erroneous detection due to deterioration of the functions of the sound wave detector and the like.

[0013]

The present invention employs the following means to solve the above-mentioned problems.

That is, an amplifier for amplifying a signal of a sound wave detector attached through an acoustic tube having one end inserted into a furnace, a gate circuit for inputting the output of the amplifier, and an output for the gate circuit. An input high-frequency filter, a detection rectifier that detects and rectifies the output of the high-frequency filter, and a correction in which data for correcting the background noise level according to the boiler load signal and the burner operation pattern is input in advance. A command device, an offset correction circuit for inputting signals of the detection rectifier and the correction command device for correction, a gain correction circuit for inputting an output of the offset correction circuit and an output of the correction command device, and a gain correction circuit for the same. A boiler pressure section blast detection device having a monitoring device for displaying the output of
A closing detection circuit that inputs the outputs of the detection rectifier and the correction command device, and a purge unit that inputs the output of the closing detection circuit and supplies a purge fluid to the acoustic tube.

[0015]

In the above-mentioned invention, the output of the sound wave detector decreases when the in-furnace debris accumulates at the tip of the acoustic tube and the transmission of sound waves or vibration sounds decreases. Therefore, this signal is sent from the detection rectifier to the close detection circuit via the amplifier and the like.

On the other hand, the correction command device sends a threshold signal for purging to the closing detection circuit according to the current boiler load signal and the burner operation pattern. The close detection circuit outputs a purge signal to the purge means when the output from the detection rectifier is lower than the purge threshold signal. The purge means receives this signal and sends the purge fluid to the acoustic tube to scatter and remove the deposits.

Similarly, the correction command device sends a threshold signal for self-diagnosis to the close detection circuit. The closing detection circuit sends a sensor abnormality signal to the monitoring device when the output from the detection rectifier is lower than the threshold signal for the self-diagnosis during the operation of the purging means and the detection rectifier. The monitoring device receives this signal and outputs a sensor abnormality.

As described above, deposits in the sound tube portion are detected, the sound tube is automatically cleaned, and the reliability is greatly improved. In addition, self-diagnosis of a device such as a sound wave detector becomes possible.

[0019]

An embodiment of the present invention will be described with reference to FIGS. The parts described in the conventional example are assigned the same reference numerals, and the description thereof will be omitted. The parts related to the present invention will be mainly described.

In FIG. 2, evaporating tubes 1 are arranged in a furnace wall 3 of a boiler main body 01. The tip of the sound tube 02 is inserted into the furnace wall 3 (FIG. 2, (a)). Hearing tube 0
One end of 2 has an opening D between the evaporation tubes 1, and the other end is connected to a sound wave detector 03 (FIG. 2, (b)). The sound tube 02 is connected to the outside of the furnace wall 3 by a flange 7, and a purge air pipe 8 is provided in the flange portion. Air piping 8
Is connected to an air source via a purge on-off valve 25.
2 is a heat insulating material.

The output of the sound wave detector 03 is sent to an amplifier 04 as shown in FIG. Correction command device 2
9a is a boiler load signal 10s and a plurality of burners ON /
The OFF signal 11s is input. The close detection circuit 23 receives the output of the detection rectifier 06 and the correction command device 29a, and sends the output to the monitoring device 07a and the purge opening / closing valve (electromagnetic valve) 25. In the above, the air pipe 8 and the purge on-off valve 2
5 is a purge means.

In the above, the in-furnace sound wave is output from the sound wave detector 03.
The sound level amplified by the voltage amplifier 04 is converted into a DC signal by the high-pass filter 05 and the detection rectifier 06 having the cutoff frequency (fc) shown in FIG. , An offset correction circuit 27 and a gain correction circuit 28, and are input to the monitoring device 07a. The output of the detection rectifier 06 is input to the closing detection circuit 23.

FIG. 3 shows an example of the frequency analysis result of the output signal of the voltage amplifier 11, which shows the high-pass components (hatched portion) of the horizontal axis frequency, the vertical axis sound pressure level, and the cutoff frequency (fc). ing. In the figure, a and b show differences in background noise level depending on the boiler load, burner operation pattern, and sensor position. a is the case where the background noise level is small, and b is the case where the high frequency component is included despite the background noise level.

FIG. 4 shows an example of the output of the detection rectifier 06 on the horizontal axis. The left half of FIG. 4 shows the background noise level in the steady state, and a and b in FIG. 4 correspond to a and b in FIG. doing. The right half shows the level of abnormal sound due to blasting. In the figure, a is a case where the load including the burner operation pattern is low, or an example at a position farther from the burner, and b is a case where the load is high,
Or, it is an example of a position near the burner. In general, the background noise level increases with the load, and the background noise level increases nearer to the burner, and the level difference from the abnormal sound decreases.

As described above, in order to eliminate the above-mentioned actual situation at the boiler load, the burner operation pattern and the position of the sound wave detector 03 (02), the load (load signal 10 s) and the burner operation pattern (burner ON / OF
The background noise level and the gain correction value of each sound wave detector 03 for the F signal 11s) are obtained and stored in the correction command device 29a. Then, in actual operation, the output of the detection rectifier 06 is corrected by the offset correction circuit 27, and the background noise level is set near zero. The gain of the output of the offset correction circuit 27 is corrected by a gain correction circuit 28.

The output of the gain correction circuit 28 is supplied to the monitoring device 07.
is input to a. Then, the threshold value is compared with a preset threshold value for the abnormal sound level shown in the example of FIG. 4, and if the threshold value is exceeded, it is determined that blasting has occurred and an alarm is output.
Further, the monitoring device 07a also displays a state such as a detection level.

The monitoring device 07a, the same boiler load and experimentally beforehand by the burner operation pattern, stored seek thresholds TH ₁ as shown in FIG. Then, at the time of actual operation, it is output to the close detection circuit 23.

The closing detection circuit 23 receives the output of the detection and rectification circuit 06 and the threshold (TH ₁ ) signal 24s, and when the output is below the threshold as shown in FIG. It is determined that the opening D is closed by ash, slag, or the like, and the sound wave is partially blocked. And it outputs to the purge on-off valve 25 and the monitoring apparatus 07a. Purge on-off valve 2
5 is opened by this signal. Then, purge air is injected to remove the deposit.

On the other hand, the monitoring device 07a receives the signal, during the purge period, a higher threshold TH ₂ of FIG. 5, when the output of the gain correction circuit 28 is small, sonic detectors 03
And the like, and outputs an alarm or the like. Was a higher threshold TH ₂ during the purge period for compressed air injection in the position close to the sound wave detector 03, sonic level is because an extremely high value as compared with the background noise.

As described above, blasting can be monitored with high accuracy without being affected by the boiler load, burner operation pattern, sensor mounting position, and the like. Further, automatic detection of deposits at the opening of the acoustic tube, automatic purging, and automatic self-diagnosis of the detection sensor using the purging sound can be performed, and the reliability is greatly improved.

[0031]

As described above, the present invention has the following effects. (1) Since only the abnormal sound due to the blast is detected by correcting the sound pressure level of the inherent difference depending on the boiler load, the burner operation pattern, and the sensor mounting position, high-precision detection is possible. (2) The reliability of detection is improved by evaluation of the presence or absence of deposits in the opening of the acoustic tube, self-diagnosis of the sensor using an automatic purge and a purge sound. (3) Due to the above (1) and (2), it is possible to detect the blasting of the pressure portion, which is smaller than that of the conventional device, with high accuracy and to construct a highly reliable system.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of an embodiment of the present invention.

FIG. 2 is a detailed view of a sound tube section of the embodiment.

FIG. 3 is an operation explanatory view of the embodiment.

FIG. 4 is an operation explanatory view of the embodiment.

FIG. 5 is an operation explanatory view of the embodiment.

FIG. 6 is a configuration block diagram of a conventional example.

FIG. 7 is an operation explanatory view of the conventional example.

FIG. 8 is an operation explanatory view of the conventional example.

FIG. 9 is an operation explanatory view of the conventional example.

FIG. 10 is an operation explanatory view of the conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 01 Boiler main body 03 Sound wave detector 04 Voltage amplifier 05 High-pass filter 06 Detection and rectification circuit 07, 07a Monitoring device 08 Gate circuit 8 Purge air pipe 09 Gate signal device 10s Boiler load signal 23 Close detection circuit 25 Purge opening / closing valve 27 offset correction circuit 28 gain correction circuit 29, 29a correction command device

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F22B 37/42 F22B 37/38

Claims (1)

(57) [Claims] 1. An amplifier for amplifying a signal of a sound wave detector mounted through a sound tube inserted at one end into a furnace;
A gate circuit for inputting the output of the amplifier, a high-frequency pass filter for inputting the output of the gate circuit, a detection rectifier for detecting and rectifying the output of the high-frequency filter, and operating the boiler load signal and burner in advance A correction command device that inputs data for correcting the background noise level in accordance with the pattern, an offset correction circuit that inputs signals of the detection rectifier and the correction command device to perform correction, an output of the offset correction circuit, In a boiler pressure section blast detection device having a gain correction circuit for inputting an output of a correction command device and a monitoring device for displaying an output of the gain correction circuit, a closing detection for inputting outputs of the detection rectifier and the correction command device. A boiler pressure comprising a circuit and a purge means for receiving an output of the close detection circuit and supplying a purge fluid to the acoustic tube. Part 噴破 sensing device.