JPH10267273A - Abnormality detecting method for flame detecting device for combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect abnormality of a flame detecting device in early time for a combustion device and deterioration of an ultraviolet ray sensor, used in a flame detecting device, through simple constitution. SOLUTION: In a flame detecting device to output a pulse-form output signal according to a quantity of light entering an ultraviolet ray sensor 7, constitution thereof is such that an output signal is monitored and abnormality of a flame detecting device is decided based on the number of pulses of an output signal per specified time. Further, in the flame detecting device, during non-combustion operation of a combustion device 2, the number of pulses of an output signal from the flame detecting device is integrated, and based on the integrated value, deterioration of an ultraviolet ray sensor 7 is decided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an abnormality of a flame detecting device in a combustion device and a deterioration of an ultraviolet ray sensor used in the flame detecting device.

[0002]

2. Description of the Related Art For example, in a combustion device used for a boiler, an incinerator, or the like, a flame detection device is attached to monitor the presence or absence of a flame and a combustion state in view of safety measures and necessity of stabilizing operation. . Some of such flame detectors use an ultraviolet sensor.

The ultraviolet sensor detects light in an ultraviolet region generated by a combustion reaction, and an ultraviolet photoelectric tube is generally used as an ultraviolet sensor for detecting a flame of such a combustion device. This UV photoelectric tube is
It has the property of reacting to light in a very narrow wavelength band in the ultraviolet region. Here, in the ultraviolet discharge tube, once the ultraviolet ray is incident, the state in which the current continues to flow continues, so that the drive circuit side is configured to output a signal in a pulsed manner. Further, this ultraviolet photoelectric tube outputs a pulse-like signal equivalent to the presence of a flame due to the incidence of cosmic rays (hereinafter, this signal is referred to as background noise) even when ultraviolet rays are not incident. This background noise, as shown in FIG.
The occurrence is more irregular than in the case where a flame is detected (see FIG. 5A), and the interval between the occurrences is relatively long. Therefore, in the conventional flame detection device, the background noise is removed and only the flame detection signal is extracted so that the background noise is not erroneously determined as a signal indicating the presence of a flame. .

In order to reliably detect the presence or absence of a flame in such a flame detection device, it is necessary to check whether the output signal is correct, that is, whether not only the ultraviolet sensor but also the entire flame detection device is normal. It is necessary to detect, and it is also necessary to detect deterioration of the ultraviolet sensor. Therefore, in the conventional flame detection device, a light-blocking means is provided at the entrance of the ultraviolet photoelectric tube, and the light-blocking means is operated in association with the control of the combustion device, thereby simulating a state without a flame during combustion. By monitoring the detection signal at this time, the aforementioned deterioration or abnormality is determined.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to find out an abnormality of a flame detecting device in a combustion device and a deterioration of an ultraviolet sensor used in the flame detecting device at an early stage with a simple configuration. It is.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the invention according to the first aspect has a pulse-like output according to the amount of ultraviolet light incident on an ultraviolet sensor. A flame detection device for outputting a signal is characterized in that the output signal is monitored and abnormality of the flame detection device is determined based on the number of pulses of the output signal per fixed time. Further, according to a second aspect of the present invention, there is provided a flame detecting device which outputs a pulse-like output signal in accordance with an amount of ultraviolet light incident on an ultraviolet sensor, wherein the output signal from the flame detecting device is provided when the combustion device is not burning. Are integrated, and the deterioration of the ultraviolet sensor is determined based on the integrated value.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is embodied in a flame detecting device for a combustion device. This combustion device is used in a boiler, an incinerator, or the like, and the flame detection device has a function of monitoring a state of formation of a flame in the combustion device, and detecting a combustion abnormality such as misfiring or extinction. is there.
And the ultraviolet sensor used for this combustion apparatus is arrange | positioned facing the flame formation part of a combustion apparatus. The flame detection device according to the present invention is configured to output a pulse signal in accordance with the amount of ultraviolet light incident on the ultraviolet sensor.
As this ultraviolet sensor, for example, an ultraviolet photoelectric tube is used.

In the method of the present invention, an output signal from the flame detection device is monitored, and an abnormality of the flame detection device is determined based on the number of pulses of the output signal per a fixed time.
If the number of pulses of the output signal per fixed time is out of the normal range, it is determined that the flame detector is abnormal. The abnormality of the flame detection device includes, in addition to the abnormality of the ultraviolet sensor, an abnormality of a drive circuit of the ultraviolet sensor, an output circuit, and the like. Here, the normal range is when the flame detection device is normal. And the range of the number of pulses of the output signal that can be output per fixed time. That is, when the number of pulses per fixed time that is not considered due to the configuration of the flame detection device is output, it is determined that the flame detection device is abnormal. Here, when continuously obtaining the number of pulses per fixed time for the output signal, the number of pulses per certain time can be obtained immediately after the number of pulses per certain time is obtained. It is also possible to partially overlap the predetermined time for calculating the number and obtain the number of pulses per the next predetermined time. It is preferable that the change in the number of pulses can be quickly detected by overlapping the predetermined times for obtaining the number of pulses in this manner. Further, in this flame detection device, the presence or absence of a flame is detected based on the number of pulses per fixed time.

Further, according to the present invention, during the non-combustion operation of the combustion device, the number of pulses of the output signal from the flame detection device is integrated, and the deterioration of the ultraviolet sensor is determined based on the integrated value. The non-combustion operation of the combustion device refers to a state in which a flame should not be formed on control.In such a combustion device, at the time of pre-purge before the ignition operation or at the time of post-purge during the fire-extinguishing operation. Etc. During this non-combustion operation, the number of pulses of the output signal from the flame detection device is integrated. If the integrated value is equal to or larger than the set value, it is determined that the ultraviolet sensor has deteriorated. This set value is determined based on the background noise occurrence rate during normal operation without deterioration in the ultraviolet sensor. That is, the set value is set to a value larger than the number of pulses of the background noise expected to occur within the time for integrating the number of pulses. Also, this set value is set smaller than the value that determines that there is a flame when converted into the number of pulses per fixed time described above. The above-described integration of the number of pulses can be performed in the entire period during the non-combustion operation. However, the period during the non-combustion operation is divided into a plurality of periods, and each period is integrated and compared with the set value. You can also. That is, in the present invention, the deterioration of the ultraviolet sensor is determined by noting that the background noise in the ultraviolet sensor increases with the deterioration of the ultraviolet sensor.

As described above, in the abnormality detecting method of the present invention, the abnormality of the flame detecting device and the deterioration of the ultraviolet sensor itself are detected based on the output signal from the ultraviolet sensor without using the conventional light shielding means. can do.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an explanatory diagram of a processing procedure according to a first embodiment of the present invention, FIG. 2 is an explanatory diagram of a procedure for obtaining the number of pulses of an output signal per fixed time, and FIG.
FIG. 4 is an explanatory view showing the relationship between the respective criteria in the present invention.
FIG. 1 is an explanatory diagram of a specific example of a combustion device to which the present invention is applied.

First, an example of a combustion apparatus to which the present invention is applied will be described with reference to FIG. This combustion device is a boiler combustion device. In FIG. 4, a boiler 1 has a combustion device 2 mounted on an upper portion thereof. The combustion device 2 includes a fuel pipe 3 and a wind box 4 serving as a supply path of combustion air. Further, a fuel valve 5 is connected to the fuel pipe 3 in the middle thereof, and a blower 6 is connected to an upstream end of the wind box 4. An ultraviolet sensor 7 is attached to the upper part of the wind box 4. Further, a water level sensor 8 and a water supply pump 9 as water supply means are connected to the boiler 1.

The ultraviolet sensor 7 uses an ultraviolet photoelectric tube, and its light receiving portion is disposed so as to face a flame forming portion in the combustion device 2. In this embodiment, the drive circuit and the output circuit are integrated into the ultraviolet sensor 7, so that the ultraviolet sensor 7 outputs a pulse-like output signal corresponding to the incidence of ultraviolet light.

In the combustion device 2 shown in FIG. 4, the control device of the combustion device 2 and the ultraviolet sensor 7 of the flame detection device are used.
The other parts are configured to be incorporated in the control device 10 of the boiler 1. Therefore, the control device 10 determines the operating state of the boiler 1 based on the detection signals from the ultraviolet sensor 7 and the water level sensor 8 and controls the fuel valve 5, the blower 6, and the water supply pump 9, thereby The automatic control of the boiler 1 including the control of the combustion device 2 and the detection of the flame is performed. Further, when detecting an abnormal state of the boiler 1 or the combustion device 2, the control device 10 notifies the notification means 11, 12.
To notify the abnormal state. These notification means 1
Reference numerals 1 and 12 denote, for example, an acoustic notifying unit 11 that emits and notifies an alarm sound such as a siren, a buzzer, and a bell, and a visual notification such as a lamp, an indicator, and a display device. Display type notification means 12
It is.

The control device 10 is constituted by a microcomputer. That is, the control device 10 includes a storage device 14 in which a processing procedure of control during normal operation and control when an abnormality occurs is stored as a program (software) in an arithmetic device (CPU) 13, an ultraviolet sensor 7, a water level sensor 8 and the detecting means and the combustion device 2,
It is configured by connecting an interface device 15 for inputting and outputting a signal between the control target devices such as the blower 6 and the water supply pump 9 and the arithmetic unit 13. The control device 10 controls the control target device based on detection signals from detection means such as the ultraviolet sensor 7 and the water level sensor 8 while referring to a processing procedure in the storage device 14.

First, the control operation of the control device 10 will be described. The control device 10 controls the combustion device 2 based on a signal from the ultraviolet sensor 7 during normal operation of the boiler 1. The control of the combustion device 2 detects a load request to the boiler 1 as a change in pressure inside the boiler 1 and controls the fuel valve 5.
At the same time, water supply control to the boiler 1 is performed based on a signal from the water level sensor 8.

The control of the controller 10 at this time is as follows. That is, when the operation of the boiler 1 is started, the control device 10 starts the blower 6 prior to the actual combustion and performs a pre-purge in the furnace. After the pre-purge operation for a predetermined time, the fuel valve 5 is opened to start supplying fuel. This fuel is ignited by an ignition device (not shown), actual combustion is started, and the boiler 1 generates steam. When the required load on the boiler 1 is reduced, the combustion device 2 is temporarily stopped and put into a standby state, or when the operation of the boiler 1 is stopped after the operation for a desired time, first, the fuel valve 5 to shut off the supply of fuel to extinguish the fire. Then, the blower 6 is operated as it is to post-purge the exhaust gas after combustion from the boiler 1. After the post-purge operation is performed for a predetermined time, the blower Stop 6.

Now, the abnormality detection method of the present invention will be described.
The procedure of the combustion control of the combustion apparatus 2 will be described with reference to FIGS. In the present invention, the background noise in the ultraviolet sensor 7 is used to determine the abnormality of the ultraviolet sensor 7. Therefore, in the control device 10, in order to accurately detect the flame,
It is configured to prevent erroneous detection of a flame due to background noise. Therefore, in the control device 10, the pulse-like output signal from the ultraviolet sensor 7 is monitored, the number of pulses of the output signal per certain time is obtained, and the flame detection and the abnormality of the flame detection device are performed based on this pulse number. Is being detected.

That is, the output signal from the ultraviolet sensor 7 is sequentially stored as data in the storage device 14 via the interface device 15 and the arithmetic device 13, and the arithmetic device 13 stores the data in the storage device 14. By reading and calculating, the detection of the flame and the abnormality of the flame detection device are detected. Here, when calculating the number of pulses per fixed time as described above, as shown in FIG. 2A, the fixed time A for calculating the number of pulses is partially overlapped to obtain the number of pulses per next fixed time. ing. If the number of pulses of the output signal per a fixed time A is obtained in this way, the interval B for obtaining the number of pulses is shorter than the fixed time A, so that a change in the number of pulses can be detected earlier.

When the combustion device 2 is to be started, the control device 10 starts the blower 6 to start pre-purge in the boiler 1 in step S1, and thereafter, for a predetermined period of time, as described above. The number of pulses per output signal is obtained, and flame monitoring is started based on the number of pulses.
Then, in step S2, it is determined whether or not the number of pulses of the output signal per fixed time is within the normal range.

That is, in the present invention, a pulsed or alternating drive voltage is applied to the ultraviolet sensor 7 in order to obtain a pulsed output signal from the ultraviolet sensor (ultraviolet phototube) 7. Therefore, if the ultraviolet sensor 7 and its drive circuit and detection circuit operate normally,
The number of pulses of the output signal from the ultraviolet sensor 7 per fixed time falls within a certain range based on the drive voltage, and the magnitude of the output signal also falls within a certain range based on the drive voltage. is there. However, when an abnormality occurs in the ultraviolet sensor 7 or its drive circuit or detection circuit, and the frequency or voltage of the drive voltage greatly increases, the output signal when the number of pulses of the output signal per fixed time is normal is reduced. It greatly deviates from the range that can be taken. Therefore, as shown in FIG. 3, a range (normal range) in which the output signal can be taken in a normal state is set in advance, and if the number of pulses of the output signal per fixed time is larger than this range, it is determined that the output signal is abnormal. At this time, it is preferable that the value for judging the abnormality be a value larger than the upper limit of the normal range, as shown in FIG.

When it is determined that an abnormality has occurred in the flame detecting device, the control device 10
In step S3, the acoustic notifying means 11 is operated to notify the failure of the boiler 1, and the display notifying means 12 displays that the ultraviolet sensor 7 is deteriorated. In step S4, the combustion device 2 is stopped.

On the other hand, if it is determined in step S2 that the flame detection device is normal, it is determined in step S5 whether the number of pulses of the output signal per predetermined time is equal to or greater than the flame level. That is, as shown in FIG. 3, the control device 10 determines that there is a flame when the number of pulses per predetermined time of the output signal from the ultraviolet sensor 7 is equal to or more than a predetermined number, and determines that there is a flame. Judge that there is no flame. If it is determined in step S5 that the number of pulses of the output signal per fixed time is equal to or less than the flame level, the process proceeds to step S6. During the above processing, the number of pulses of the output signal from the ultraviolet sensor 7 is integrated, and in this step S6, it is determined whether or not this integrated value is equal to or larger than a set value.

In step S6, if the integrated value of the pulse number is less than the set value, the ultraviolet sensor 7
Is not deteriorated, the process proceeds to step S8, and it is determined whether or not the pre-purge time has elapsed. Until the predetermined pre-purge time is reached, the process proceeds from step S2 to step S5.
→ Step S6 → Step S8 → Step S2 are repeatedly executed. During this pre-purge, the controller 10
Is continuously integrating the number of pulses of the output signal from the ultraviolet sensor 7, and if the integrated value of the number of pulses is equal to or larger than the set value in step S6, it is determined that the ultraviolet sensor 7 is deteriorated. , The control device 10 proceeds to the next step S7.
Then, the acoustic notification means 11 is operated, and the ultraviolet sensor 7 is activated.
Is notified, and a display type notifying unit 12 displays that the ultraviolet sensor 7 is deteriorated. If it is determined in step S8 that the pre-purge time has expired, the flow shifts from step S8 to step S9 to start the ignition operation.

Here, if it is determined in step S5 that the number of pulses of the output signal per predetermined time is equal to or higher than the flame level, it means that a pseudo flame has occurred in the boiler 1, and step S10 Then, the acoustic notifying means 11 is operated to notify that a pseudo flame has occurred, and the display type notifying means 12 displays that the pseudo flame has occurred. Here, when it is determined that a pseudo flame has occurred, an abnormality has occurred in the ultraviolet sensor 7 or its drive circuit or detection circuit, or noise has entered the flame detection device, and the output signal per predetermined time has This is the case where the number of pulses is equal to or higher than the flame level. In particular, at the time of this determination, it is further monitored whether or not the state at or above the flame level has continued for a predetermined time, and whether or not the state at or above the flame level is transient is determined. It is possible to distinguish between a momentary abnormality caused by noise entering the flame detection device or a failure of the flame detection device.

In the above procedure, step S
By detecting the abnormality of the flame detection device in 2 continuously after the ignition of the combustion device 2, the abnormality of the flame detection device can be constantly monitored even during the operation of the combustion device 2. Further, the determination of the presence or absence of the flame in the step S5 is continuously performed after the ignition of the combustion device 2, so that the state of the flame during the operation of the combustion device 2 is constantly monitored. Here, as shown in FIG. 3, a defective combustion area is set within the range of the level with a flame, and if the number of pulses of the output signal per the predetermined time is within this range, it is determined that the combustion is defective. For example, it may be configured to determine that the combustion is normal combustion, and such a configuration is preferable in operating the combustion device 2 safely and efficiently. For example, when the flame is extinguished during the combustion even though the flame detection device is abnormal, the fuel valve 5 is closed and the combustion device 2 is stopped to prevent the outflow of fuel. be able to.

In the above description, to determine the number of pulses of the output signal per fixed time, as shown in FIG.
The target section is accumulated while moving it in an overlapping state with respect to the current time. In addition, as shown in FIG. 2 (b), a section is set for each fixed time A, and each section is set. , And the number of pulses.

[0028]

As described above, according to the present invention, in a flame detecting device which outputs a pulse-like output signal in accordance with the amount of ultraviolet light incident on an ultraviolet sensor, the output signal is monitored and the In order to determine the abnormality of the flame detection device based on the number of pulses of the output signal of the above, not only the abnormality of this ultraviolet sensor, but also the abnormality of the entire flame detection device including the circuit related to the signal from the ultraviolet sensor should be discovered at an early stage. Can be. Further, according to the present invention, in the above-described flame detection device, during a non-combustion operation of the combustion device, the number of pulses of the output signal from the flame detection device is integrated, and the deterioration of the ultraviolet sensor is determined based on the integrated value. Therefore, the deterioration of the flame detecting device can be found at an early stage.

As described above, according to the present invention, it is possible to detect an abnormality of the flame detecting device and the deterioration of the ultraviolet sensor itself based on the output signal from the ultraviolet sensor without using the conventional light shielding means. it can.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a processing procedure of an abnormality detection method according to the present invention.

FIG. 2 is an explanatory diagram of a procedure for obtaining the number of pulses of an output signal per fixed time.

FIG. 3 is an explanatory diagram showing a relationship between respective judgment criteria in the present invention.

FIG. 4 is a diagram illustrating a specific example of a combustion apparatus to which the abnormality detection method according to the present invention is applied.

FIG. 5 is an explanatory diagram showing an output form of an output signal from an ultraviolet photoelectric tube.

[Explanation of symbols]

 2 Combustion device 7 Ultraviolet sensor 10 Control device

Claims (2)

[Claims] 1. A flame detecting device for outputting a pulse-like output signal in accordance with the amount of light incident on an ultraviolet sensor, wherein the flame detector monitors the output signal and outputs a flame based on the number of pulses of the output signal per a predetermined time. An abnormality detection method for a flame detection device in a combustion device, comprising determining an abnormality in a detection device. 2. A flame detection device which outputs a pulse-like output signal in accordance with the amount of light incident on an ultraviolet sensor 7, wherein the number of pulses of the output signal from the flame detection device when the combustion device 2 is not burning. And an abnormality detection method for the flame detection device in the combustion device, wherein the deterioration of the ultraviolet sensor 7 is determined based on the integrated value.