JP2846192B2 - 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 blasting 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. 5, a boiler body 01 having a plurality of burners
A sound wave detector 03 is mounted on the furnace wall of the. The output of the sound wave detector 03 is sent to the monitoring device 07 through the amplifier 04, the gate circuit 08, the high-pass filter 05, and the detection rectifier 06 in this order. In the figure, reference numeral 09 denotes a gate signal device.

In the above, the output voltage from the sound wave detector 03 is amplified by the voltage amplifier 04 to an appropriate voltage. 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, monitors the detection status, and records or displays the output or issues an alarm or the like when the output is equal to or higher than a set level.

[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 c and d 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.

The output of the detection rectifier 06 is connected to a monitoring device 07
And an alarm is issued when the output level becomes higher than the set level.

[0007]

The above-mentioned conventional apparatus has the following problems. (1) 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. (2) When the level difference between the background noise and the abnormal sound is small, it is difficult to detect (see the signal d in FIG. 6).

[0008]

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

That is, as a pressure part blast detection device, a detector attached to a boiler and detecting at least one of a sound wave and a vibration in a furnace, an amplifier receiving an output of the detector, and an output of the amplifier A high-pass filter that receives
A detection rectifier that receives the output of the high-pass filter, a correction unit that receives the load signal of the boiler, and corrects the output of the detection rectifier; Display means for displaying the blast of the pressure section.

[0010]

According to the above means, at least one of the sound wave and the vibration in the furnace during the operation of the boiler is detected by the detector. The output of the detector is amplified by an amplifier and then passed by a high-pass filter at a predetermined frequency or higher. This signal is detected and smoothed by a detection rectifier. When the pressure section of the boiler blows, the output of the detection rectifier suddenly increases.

The correcting means removes background noise and corrects the amplitude of the detected and smoothed signal in accordance with the load signal of the boiler. Then, the output from the correction means is usually at a low level, but at the time of blasting it is clearly at a high level. The display means receives the output of the correction means and detects and displays an increase in signal level due to the occurrence of blast of the pressure section of the boiler.

In this way, the background noise and the fluctuation of the level increase, which change depending on the mounting position of the detector and the load condition of the boiler, are corrected, and the occurrence of the blast of the pressure portion can be detected accurately.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One 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. 1, the output of the detection and rectification circuit 06 is sent to a monitoring device through an offset level correction circuit 7 and a gain level correction circuit 8 in order.

Also provided is a correction command device 9 which receives a boiler load signal 10s and sends a correction signal to an offset level correction circuit 7 and a gain level correction circuit 8.

In the above, the sound wave appropriately amplified by the voltage amplifier 04 is supplied to the gate circuit 08, the high-pass filter 05,
The signals are input to the correction circuits 7 and 8 via the detection rectifier 06.

FIG. 2 shows an output example of the detection rectifier 06. The left half of the figure shows the background noise level of the boiler, and the left half shows the generation level of abnormal sound due to blasting. In the figure, signals a and b
The difference is caused by the load or the position of the detector (sensor) 02. For example, the signal a is a case where the load is low (the background noise level is small and the difference from the abnormal sound is large), and the signal b is a case where the load is high. In the case of (the background noise level increases and the level difference from the abnormal sound is small), the background noise level increases with the load and the level difference from the abnormal sound decreases.

FIG. 3 shows the result of frequency analysis of the original signal output from the voltage amplifier 04 for the sake of simplicity. The signals a and b show the difference in the background noise level depending on the position of the load or the sensor. It was done. Signal a is a case where only the cut frequency (f _c) below the level of the high-pass filtering device 05 is present. Signal b is the case that there are levels greater than f _c, there is a potential for false detection that contains high frequency components despite the background noise level.

In order to eliminate the above-mentioned situation at the boiler load or the sensor position, the background noise level of each sensor with respect to the boiler load is experimentally detected in advance and input and stored in the correction command device 9. . Then, the correction command device 9 receives the load signal 10s and sends an offset level signal 11s corresponding to the load signal to the correction circuit 7, as shown in FIG. The correction circuit 7 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 9 in order to facilitate the detectability. Then, the correction command device 9 receives the load signal 10s and receives the load signal 10s as shown in FIG.
As shown in FIG.
s is sent to the correction circuit 8. The correction circuit 8 corrects the output of the correction circuit 7 (detection and rectification circuit 06) 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, it is possible to reliably detect the blast abnormality. Furthermore, the inherent difference of the sensor mounting position can be removed, and the abnormality can be detected more reliably.

As described above, the detection and early detection of the minute blast can be performed by the conventional apparatus.

In the above description, the detector 03 is a sound wave detector, but may be a vibration detector. Also, a combination of these may be used.

[0024]

As described above, according to the present invention, abnormal sound can be reliably identified by correcting the output level determined by the state of the boiler load and the detector position according to the boiler load state. Will be For this reason, the detection reliability is improved and the abnormal sound can be reliably detected.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a pressure part blast detection device according to one embodiment of the present invention.

FIG. 2 is an operation explanatory view 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 a configuration block diagram of a conventional example.

FIG. 6 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 rectifier 07 Monitoring device 08 Gate circuit 09 Gate signal device 7 Offset correction circuit 8 Voltage amplification correction circuit 9 Correction command device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-115614 (JP, U) JP-B-47-20743 (JP, B1) (58) Fields surveyed (Int. Cl. ⁶ , DB name) F22B 37/42 F22B 37/38

Claims (1)

(57) [Claims] 1. A detector attached to a boiler for detecting at least one of sound waves and vibrations in a furnace, an amplifier receiving an output of the detector, and a high-pass filter receiving an output of the amplifier. And a detection rectifier receiving the output of the high-pass filter, receiving a load signal of the boiler, correcting means for correcting the output of the detection rectifier, when receiving the output of the correction means is equal to or more than a predetermined value, Display means for displaying blasting of the pressure portion of the boiler.