JPH07190350A - Device for detecting sound in boiler furnace - Google Patents

Abstract

PURPOSE:To provide a device for detecting a boiler sound in which it has a superior responding characteristic, an occurrence of phenomenon of boiler sound can be positively detected irrespective of any type of furnace and a positive control of ignition and extinguishing of a burner is made possible. CONSTITUTION:There are provided an inter-furnace vibration detecting means 1 for detecting an inter-furnace atmosphere vibration caused by combustion at a burner and converting it into an electrical signal; means 2, 3 for processing the electrical signal; and a sensing means 4 for comparing the processed electrical signal with a judged value. The judged value is set to be a level between a signal value corresponding to the inter-furnace atmosphere vibration corresponding signal value and an inter-furnace atmosphere vibration corresponding signal value when the boiler sound occurs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a can noise detecting device in a fired furnace such as a boiler or an industrial furnace.

[0002]

2. Description of the Related Art In a boiler, an industrial furnace, etc., in many cases, the rated value is largely turned down (output is reduced) in accordance with a required load. In this case, the balance of fuel, air flow rate, furnace temperature, etc. may decrease, and under certain conditions, a resonance phenomenon may occur and abnormal vibration may occur.

Such abnormal vibrations are called "canning" and occur irregularly under specific conditions. When this abnormal vibration occurs, there is a high possibility that the refractory inside the furnace, the water pipe for steam generation, etc. will be damaged and the life of the furnace will be shortened.

This "cannon" is caused by the fuel flow rate, air flow rate,
It is considered that many combustion parameters such as furnace temperature and atomizing pressure occur in an environment in a specific state.

Pressure fluctuations and the like caused by combustion trigger, causing large oscillations at the natural frequency of the furnace.

[0006]

The occurrence of this vibration can be detected by using a sensor such as a vibrometer, but conventionally it is detected from outside the furnace. In a large furnace, even if abnormal vibration occurs inside the furnace, it takes time until the furnace body starts to vibrate, so there is a delay in detection. (2) Around the furnace, there are many devices and Since the machine is installed, it is difficult to distinguish between these vibrations and the vibration of "can noise". (3) When "can noise" is detected, the burner is extinguished to eliminate the "can noise". However, there is a problem that the controllability is poor because the external sensor cannot know the local condition inside the furnace.

The present invention has been made in order to solve this problem. It has excellent responsiveness and can reliably detect canning regardless of the type of furnace without being affected by noise outside the furnace. An object of the present invention is to provide a canning noise detection device that enables precise control of burner extinguishing when canning noise occurs.

[0008]

In order to achieve the above object, the present invention provides, in claim 1, in-reactor vibration detection means for detecting in-reactor atmospheric vibration caused by combustion of a burner and converting it into an electric signal. A means for processing the electric signal and a detecting means for comparing the processed electric signal with a judgment value are provided, and the judgment value is the furnace atmosphere vibration corresponding signal value during normal combustion and the furnace atmosphere vibration during canning. The configuration is such that the level is between the corresponding signal value.

According to a second aspect of the present invention, the signal value corresponding to the atmosphere vibration in the furnace is a value corresponding to the amplitude of the sound in the furnace.

According to a third aspect of the present invention, the signal value corresponding to the atmosphere vibration in the furnace is a square value of a value corresponding to the amplitude of the sound in the furnace.

[0011]

According to the present invention, the atmosphere vibration in the furnace during burner combustion is monitored, and the can squeal is detected from the change in the atmosphere vibration in the furnace.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a sensor (microphone in this example) for detecting atmospheric vibration in the furnace, 2 is a preamplifier, 3 is a smoothing circuit, 4 is a detection circuit constituted by a comparator, and 5 is a judgment value Z. It is a judgment value setting circuit to be set.

FIG. 2 is a diagram for explaining a method of installing the microphone. In the figure, 20 is the furnace wall, 21 is the inside of the furnace, 22 is the outside of the furnace, 23 is a burner, 24
Is an oil gun, and 25 is a probe. The probe 25 guides the pressure oscillation inside the furnace to the microphone 1 in the form of audible sound or static pressure fluctuation. The tip of the probe 25 faces the vicinity of the ignition point where the fuel of the burner starts burning, and the outside of the furnace. A microphone 1 is provided at the end.

The present inventors have used the microphone 1
The experiment of taking out and analyzing was repeated. Figure 8 ~
FIG. 13 shows a representative example of the experimental results. FIG. 8 shows the waveform of the in-furnace sound during normal combustion, and FIG. 9 shows the frequency distribution of the in-furnace sound during normal combustion. FIG. 10 shows a waveform of the in-furnace sound at the early stage of can squeal generation, which has a larger amplitude than in the case of FIG. FIG. 11 shows the frequency distribution of the in-furnace sound in the early stage of the generation of canning noise, which approaches a resonance waveform having many specific frequency components as compared with the case of FIG.

FIG. 12 shows the waveform of the sound inside the furnace when the canning becomes severe, and is a saturated waveform in the resonance state. FIG. 13 is a frequency distribution of the in-furnace sound when the canning becomes severe, in which the component near 160 Hz increases rapidly and the other high-frequency components decrease.

From the waveform comparisons of FIGS. 8, 10 and 12, the amplitude at the beginning of can squealing is compared with the amplitude during normal combustion.
It is understood that the amplitude when the squealing of the can is intense is considerably large. By utilizing this amplitude (level) difference, it is possible to distinguish between normal combustion and canning.

In the embodiment of FIG. 1, the judgment value Z is set for this identification. The microphone 1 takes out the in-furnace sound as an electric signal, amplifies it with the preamplifier 2, smoothes it with the smoothing circuit 3, and compares the level of the smoothed signal A with the judgment value Z with the detection circuit 4. The detection circuit 4 is A
If it is> Z, a canning noise detection signal (H level) is output.

The discriminant value Z is a value at which the signal level when the canning becomes severe can be discriminated from the signal level during normal combustion, or the signal level at the beginning of canning is discriminated from the signal level during normal combustion. This is a possible value.

In the present embodiment, when the in-furnace sound is monitored, and when the in-furnace sound becomes equal to or higher than the determination value Z, it is determined that "canning" occurs. Therefore, before the in-furnace vibration is transmitted to the furnace body, Can ringing "detection can be performed.

Also, since "canning" can be detected based on the sound inside the furnace, there is no fear of being affected by the vibration of the equipment and auxiliary equipment around the furnace.

Also, by monitoring changes in the sound inside the furnace, "canning"
Since the detection is performed, the burner can be extinguished depending on the situation inside the furnace.

In the example of FIG. 1, the number of the detection circuit 4 is one, but another detection circuit is provided, and the detection circuit 4 uses the signal level at the time of the normal combustion as the judgment value to determine the signal level when the can squeaking becomes severe. A value that can be discriminated from the signal level may be used, and the other detection circuit may use a value that can discriminate the signal level at the initial stage of can squeal occurrence from the signal level at the time of normal combustion.

Further, from the comparison of the frequency components of FIGS. 9, 11 and 13, it is understood that the frequency component (a component near 160 Hz) characterized by the can noise rapidly increases when the can noise occurs. By monitoring the signal of the frequency component, it is possible to distinguish between normal combustion and canning.

In FIG. 3, a band pass filter 6 having a pass band around 160 Hz is provided in the next stage of the preamplifier 2,
This is a device configured to extract the signal of the frequency component characterized by canning and smoothing it, and then compare it with the determination value Y in the detection circuit 4. Reference numeral 7 is a circuit for setting the judgment value Y.

FIG. 4 shows a third embodiment of the present invention. The signal A smoothed by the smoothing circuit 3 of FIG. 1 is squared by an energy calculation circuit (square calculation circuit) 8 and the calculated value is obtained. A
² is compared with the judgment value E ₁ . Reference numeral 9 is a judgment value setting circuit for setting the judgment value E ₁ . In this embodiment, since the in-furnace sound is made into a quadratic function, the difference between the value during normal combustion and the value during canning becomes larger than that in the case of FIG. 1, and the canning detection accuracy is improved.

FIG. 5 shows an embodiment in which the energy calculating circuit 8 is provided in the embodiment of FIG. 3, and the value at the time of normal combustion and the value at the time of can squealing are compared with the case of the embodiment of FIG. The difference is larger than in the case of FIG. 3, and the can squeal detection accuracy is further improved. Reference numeral 10 is a judgment value setting circuit for setting the judgment value E ₂ .

An example of using a pressure sensor in place of the microphone 1 is shown in FIGS. 6 and 7. In the figure,
Reference numeral 11 is a pressure sensor, 12 is a pressure / electric converter for converting the output of the pressure sensor 11 into an electric signal, 13 is a smoothing circuit, 1
Reference numeral 4 is an energy calculation circuit, 15 is a detection circuit, 16 is a judgment value setting circuit for setting a judgment value Y ₁ , and 17 is a judgment value setting circuit for setting a judgment value E ₃ .

[0029]

As described above, the present invention monitors the sound in the furnace during burner combustion and detects the can noise from the change in the atmosphere vibration in the furnace, so that it can be quickly, for example, before the can noise occurs in the furnace body. In addition, it is possible to know the occurrence of canning.

Therefore, the point extinguishing control for eliminating the squeal of the can can be performed accurately, and the damage to the refractory inside the furnace and the water pipe for steam generation and the shortening of the life of the furnace due to the squeal of the can can be prevented. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing an installation structure of a sensor such as a microphone in the above embodiment.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a block diagram showing a third embodiment of the present invention.

FIG. 5 is a block diagram showing a fourth embodiment of the present invention.

FIG. 6 is a block diagram showing a fifth embodiment of the present invention.

FIG. 7 is a block diagram showing a sixth embodiment of the present invention.

FIG. 8 is a diagram showing a waveform of a sound in a furnace during normal combustion.

FIG. 9 is a diagram showing a frequency distribution of in-furnace sound during normal combustion.

FIG. 10 is a diagram showing a waveform of a sound in the furnace at the initial stage of can squeal generation.

FIG. 11 is a diagram showing a frequency distribution of in-furnace sound at an early stage of can squeal generation.

FIG. 12 is a diagram showing a waveform of a sound in a furnace when the can is violently violent.

FIG. 13 is a diagram showing a frequency distribution of in-furnace sound at an early stage of generation in a violent can-ringing state.

[Explanation of symbols]

 1 Microphone 3 Smoothing circuit 4 Detection circuit 5, 7, Judgment value setting circuit 6 Band pass filter 8 Energy calculation circuit 9, 10 Judgment value setting circuit 11 Pressure sensor 12 Pressure / electric converter 13 Smoothing circuit 14 Energy calculation circuit 15 Detection circuit 16, 17 Judgment value setting circuit 23 Burner 25 Probe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shigeo Nakamura Inventor Shigeo Nakamura Ubei Kawara, Hijinohe City, Aomori Pref. 1-1, Tohoku Electric Power Co., Inc. Hachinohe Thermal Power Plant (72) Satoru Taniguchi 1-chome Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture 5-5 Incorporated company Kobe Steel, Ltd. Kobe Research Laboratory (72) Inventor Tatsuo Kono 1-5, Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture 5-5 Incorporated company Kobe Steel Ltd., Kobe Research Laboratory

Claims (3)

[Claims] Claim: What is claimed is: 1. In-furnace vibration detection means for detecting in-furnace atmosphere vibration caused by burner combustion and converting it into an electric signal, means for processing the electric signal, and comparing the processed electric signal with a judgment value. The can value of the furnace can be characterized in that the determination value is a level between the signal value corresponding to the atmospheric vibration in the furnace during normal combustion and the signal value corresponding to the atmospheric vibration in the furnace during canning. Detection device. 2. The can-squeal detecting device for a furnace according to claim 1, wherein the in-furnace atmosphere vibration-corresponding signal value is a value corresponding to the in-furnace atmosphere vibration amplitude. 3. The can-squeal detecting device for a furnace according to claim 1, wherein the in-furnace atmosphere vibration-corresponding signal value is a square value of a value corresponding to the in-furnace atmosphere vibration amplitude.