JPH08270902A - Boiler pressure part corruption detector - Google Patents

Abstract

PURPOSE: To prevent detection accuracy from being deteriorated owing to deposition of scattered matter in a furnace onto an opening of a sound locater pipe, and preventing false detection due to deterioration of a function of a sound wave detector upon long term use by inputting a closure detector circuit into which there are inputted outputs of a detector/rectifier and a correction instruction unit, and supplying a purging fluid to the sound locater pipe. CONSTITUTION: A closure detector circuit 23 receives outputs from a detector/ rectifier 06 and a correction instruction unit 29a and transfers the outputs to a monitor unit 07a and a purging opening/closing valve (solenoid valve) 25. An air piping 8 and the purging opening/closing valve 25 serve as purge means. The closure detector circuit 23 judges, when the output of the detector/rectifier circuit 06 is less than a threshold, that the opening of the sound locater pipe 02 is closed with ash and slug, etc., to partly shield sound waves. It outputs the judgement to the purging opening/closing valve 25 and the monitor unit 07a. The purging opening/closing valve 25 is opening owing to the signal. Thus, purging air is injected to remove deposite.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure blowout detection device for 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
A sound wave detector 03 such as a microphone is attached to the furnace wall of No. 1 via a sound 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 this order. 09 in the figure
Is a gate signal device. Reference numeral 29 is a correction command device.

In the above, the output voltage from the sound wave detector 03 is amplified to an appropriate voltage by the voltage amplifier 04. The frequency characteristic of this output is shown in FIG. 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 subjected to the offset correction and the gain correction based on the signal of the correction command device 29, monitors the detection status, records and displays the output, and the output is equal to or higher than the set level. Occasionally sends an alarm etc.

The gate signal device 09 gives a closing signal to the gate circuit 08 and blocks passage of the signal only during the time when the suit blow of the boiler is controlled. This is because a high frequency sound is emitted when the suit blow is activated, and it is difficult to distinguish it from an abnormal sound.

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, a normal sound wave level (dark noise level) during boiler operation. The right half is a boiler 0
An abnormality, that is, a blowout occurs in the pressure portion 1 for some reason, and water or steam is jetted from the injection hole at a sonic velocity, and the output is higher than the background noise level.

The output of the detection rectifier 06 is subjected to offset correction, etc., and then monitored by a monitoring device 07, and an alarm is issued when the output level exceeds a set level. By the way, the background noise level in the boiler has different characteristics depending on the boiler load and the mounting position of the detector (for example, near or far from the burner). Further, there is a case where a high frequency component exists in the background noise level depending on the position of the detector, and the accuracy of discrimination between the background noise level and the abnormal sound level due to blast 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).

Thus, in order to eliminate the difference due to the boiler load or the generation level of the abnormal sound at the position of the sensor,
The background noise level of each sensor with respect to the load of the boiler is experimentally detected in advance and is input and stored in the correction command device 29. 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. 9A. The correction circuit 27 corrects the output of the detection rectification circuit 06 according to the input, removes the background noise, and outputs it. Further, as the load becomes higher, the level difference between the background noise and the abnormal sound becomes smaller. In consideration of this, in order to facilitate the detectability, 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. And the correction command device 29
Receives the load signal 10s and, as shown in FIG. 9B, corrects the gain level signal 12s corresponding to the load signal by the correction circuit 28.
Send to The correction circuit 28 corrects the output of the correction circuit 27 in accordance with the input to facilitate the identification of the abnormal sound level and output it.

The monitoring device 07 monitors this signal and issues an alarm when the level is above the set value.

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

[0011]

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

Further, during long-term use, erroneous detection may occur due to deterioration of the function of the sound wave detector or 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 at one end through a sound tube inserted into a furnace, a gate circuit for inputting the output of the amplifier, and an output of the gate circuit are provided. Input high-frequency pass filter, detection rectifier that detects and rectifies the output of the same high-frequency filter, and correction that has previously input data for correcting the background noise level according to the boiler load signal and burner operation pattern A command device, an offset correction circuit that inputs and corrects the signals of the detection rectifier and the correction command device, a gain correction circuit that inputs the output of the offset correction circuit and the output of the correction command device, and the gain correction circuit In a boiler pressure part blowout detection device having a monitoring device for displaying the output of
A closing detection circuit for inputting the outputs of the detection rectifier and the correction command device, and a purge means for inputting the output of the closing detection circuit and supplying a purge fluid to the hearing tube are provided.

[0015]

In the above invention, when the scattered material in the furnace is deposited on the tip of the sound tube and the transmissibility of the sound wave or the vibration sound is lowered, the output of the sound wave detector is lowered. Therefore, this signal is sent from the detection rectifier to the closure detection circuit through 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 burner operation pattern. The closure detection circuit outputs a purge signal to the purge means when the output from the detection rectifier is lower than the threshold signal for purging. Upon receiving this signal, the purging means sends the purging fluid to the sound tube to scatter and remove the deposits.

Similarly, the correction command device sends a threshold signal for self-diagnosis to the closing 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 self-diagnosis during the operation of the purging means. The monitoring device receives this signal and outputs a sensor abnormality.

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

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. It should be noted that the parts described in the conventional example are denoted by the same reference numerals and the description thereof is omitted, and the parts relating to the present invention will be mainly described.

In FIG. 2, an evaporation pipe 1 is arranged in the furnace wall 3 of the boiler body 01. Further, the tip of the sound tube 02 is inserted into the furnace wall 3 (Fig. 2, (a)). Listening 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 on the flange portion. Air piping 8
Is connected to an air source via a purge opening / closing valve 25.
In the figure, 2 is a heat insulating material.

The output of the sound wave detector 03 is sent to the 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 closing detection circuit 23 receives the outputs 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 (solenoid valve) 25. Above is the air pipe 8 and purge on-off valve 2.
5 is a purging means.

In the above, the sound wave in the furnace is the sound wave detector 03.
The sound wave level converted into an electric signal 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) of FIG. 3 via the gate circuit 08. , The offset correction circuit 27, and the gain correction circuit 28, and is input to the monitoring device 07a. The output of the detection rectifier 06 is input to the closure detection circuit 23.

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

FIG. 4 shows an output example of the detection rectifier 06 on the horizontal axis. The left half of the figure is the background noise level in the steady state, and a and b in the figure correspond to a and b of FIG. are doing. The right half shows the level of abnormal sound caused by blast. In the figure, a is when the load including the burner operation pattern is low, or an example at a position far from the burner, b in the figure is when the load is high,
Or, it is an example of a position close to the burner. Generally, the background noise level increases with the load, and the background noise level increases as it gets closer to the burner, and the level difference from the abnormal sound becomes smaller.

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 10s) and the burner operation pattern (burner ON / burner ON / OF
The background noise level and 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 to set the background noise level to near zero. The gain correction circuit 28 performs gain correction on the output of the offset correction circuit 27.

The output of the gain correction circuit 28 is the monitoring device 07.
Input to a. Then, it is compared with a preset threshold value for the abnormal sound level shown in the example of FIG. 4, and when it is equal to or higher than the threshold value, it is determined that the blowout has occurred and an alarm is output.
The monitoring device 07a also displays a status such as a detection level.

In the monitoring device 07a, the threshold value TH ₁ as shown in FIG. 5 is obtained and stored experimentally in advance for each boiler load and burner operation pattern similarly to the above. Then, at the time of actual operation, it is output to the closing detection circuit 23.

When the closing detection circuit 23 receives the output of the detection rectification circuit 06 and the threshold (TH ₁ ) signal 24s and is below the threshold (A portion in the drawing) as shown in FIG. It is determined that the opening D is closed by ash, slag, etc. and the sound wave is partially blocked. Then, it outputs to the purge opening / closing valve 25 and the monitoring device 07a. Purge on-off valve 2
5 is opened by this signal. Then, purging air is jetted to remove the deposits.

On the other hand, the monitoring device 07a receives the above signal, and when the output of the gain correction circuit 28 is smaller than the high threshold value TH _{2 of} FIG. 5 during the purge period, the sound wave detector 03a.
It detects that the sensor is abnormal and outputs an alarm. The high threshold value TH ₂ is set because the sound wave level is extremely high compared to the background noise because the pressurized air is jetted at a position close to the sound wave detector 03 during the purge period.

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

[0031]

As described above, the present invention has the following effects. (1) By correcting the sound pressure level of the inherent difference due to the boiler load, burner operation pattern, and sensor mounting position, only abnormal noise due to blowout is detected, so highly accurate detection is possible. (2) Detection reliability is improved by evaluating the presence / absence of deposits in the opening of the sound tube, automatic purging, and self-diagnosis of the sensor using the purging sound. (3) Due to the above (1) and (2), it is possible to detect a smaller amount of pressure portion blasting with higher accuracy than the conventional device, and it is possible to construct a highly reliable system.

[Brief description of drawings]

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

FIG. 2 is a detailed diagram of a sound tube part of the embodiment.

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

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

FIG. 5 is an explanatory view of the operation 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 explanatory view of the operation of the conventional example.

FIG. 10 is a diagram for explaining the operation of the conventional example.

[Explanation of symbols]

 01 Boiler body 03 Sound wave detector 04 Voltage amplifier 05 High-pass filter 06 Detection rectifier circuit 07,07a Monitoring device 08 Gate circuit 8 Purge air piping 09 Gate signal device 10s Boiler load signal 23 Closure detection circuit 25 Purge opening / closing valve 27 Offset Correction Circuit 28 Gain Correction Circuit 29, 29a Correction Command Device

Claims (1)

[Claims] 1. An amplifier for amplifying a signal of a sound wave detector, one end of which is attached via a sound tube inserted into a furnace,
A gate circuit that inputs the output of the amplifier, a high-frequency pass filter that inputs the output of the gate circuit, a detection rectifier that detects and rectifies the output of the high-frequency filter, and a boiler load signal and burner operation in advance. A correction command device to which data for correcting the background noise level is input according to the pattern, an offset correction circuit for performing correction by inputting signals of the detection rectifier and the correction command device, an output of the offset correction circuit and the above In a boiler pressure part blowout detection device having a gain correction circuit for inputting the output of the correction command device and a monitoring device for displaying the output of the gain correction circuit, a closure detection for inputting the outputs of the detection rectifier and the correction command device Circuit, and a purge means for inputting the output of the closing detection circuit and supplying a purge fluid to the hearing tube. Part 噴破 sensing device.