JP2002303420A - Method for controlling flame detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for controlling a flame detector, capable of enhancing reliability of flame detecting and enhancing reliability of inspecting a flame detecting means. SOLUTION: In the method for controlling the flame detector 1 having the flame detecting means 2 and an inspecting means 3 of the means 2, the operating time A when the means 3 is operated at a predetermined time interval is constituted to be shortened a compared with a non-operating time B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a flame detecting device provided with flame detecting means and means for checking the flame detecting means.

[0002]

2. Description of the Related Art For example, a combustion device includes a flame state,
In particular, a flame detection device is provided to detect the presence or absence of a flame. The presence or absence of a flame in the combustion device is monitored by the flame detection device. If the flame disappears during the combustion of the combustion device, the supply of fuel to the combustion device is stopped. Therefore, the flame detector must always be operating normally.If the flame detector breaks down during combustion and the flame is extinguished, the flame detector may continue to output a detection signal indicating that there is a flame. , The fuel leaks as it is and is very dangerous.

Therefore, as one of the safety measures, the flame detecting device is provided with an inspection means for periodically checking during combustion whether the flame detecting device is operating normally. For example, when the flame detection device has a configuration using an ultraviolet photoelectric tube, the inspection unit has a configuration including a shutter mechanism that blocks light from entering the ultraviolet photoelectric tube. Then, the shutter mechanism is operated for a predetermined time at predetermined time intervals, and when the shutter mechanism blocks light from entering the ultraviolet phototube, a detection signal indicating no flame is output from the ultraviolet phototube. It is configured to determine whether the ultraviolet photoelectric tube is operating normally. When it is determined that an abnormality has occurred in the ultraviolet photoelectric tube, the supply of fuel to the combustion device is stopped. Here, the flame detection by the flame detection device is performed when the shutter mechanism is not operated, that is, while the shutter mechanism does not block light from entering the ultraviolet photoelectric tube.

By the way, in the above flame detecting device,
The flame cannot be detected while the shutter mechanism is operating. Therefore, in order to improve the reliability of flame detection, it is desired to shorten the time during which the shutter mechanism is operating, and to shorten the time during which flame detection is not possible. But,
In the flame detection device, the time during which the shutter mechanism operates (operating time) and the time during which the shutter mechanism does not operate (non-operating time) are usually set to be the same. Accordingly, the non-operation time is shortened. Then, since the shutter mechanism repeats the operation and the non-operation in a short time, the number of times of operation of the shutter mechanism increases, and the life of the shutter mechanism is shortened.

[0005] Further, as described above, when the operation time of the shutter mechanism is shortened, in the flame detection device,
Due to the characteristics of the ultraviolet phototube, there is also a problem that the reliability of inspection of the ultraviolet phototube becomes low. The reason why such a problem occurs will be described below.

First, a drive voltage is applied to the ultraviolet phototube in a pulsed manner at a predetermined operation cycle, and when light (ie, ultraviolet light) from a flame enters the ultraviolet phototube at the time of application of the drive voltage. , A flame detection signal is output. However, in the above-mentioned ultraviolet photoelectric tube, a phenomenon of outputting a detection signal indicating presence of a flame even when no light from the flame is incident, that is, so-called self-discharge may occur. The rate of occurrence of this self-discharge increases as the deterioration of the ultraviolet photoelectric tube progresses, and finally occurs only by applying a driving voltage.

Therefore, in the ultraviolet photoelectric tube, when the ratio of the number of detection signals with flame to the number of detection signals while the shutter mechanism is operating exceeds a predetermined value,
It is determined that the deterioration of the ultraviolet photoelectric tube has reached the use limit. That is, the deterioration state of the ultraviolet photoelectric tube is checked by detecting the rate of occurrence of self-discharge as a ratio of the number of detection signals indicating the presence of a flame when the shutter mechanism operates.

The self-discharge is a phenomenon that occurs irregularly, and does not always occur at uniform intervals. Therefore, when the operation time of the shutter mechanism is shortened, the number of detection signals during this operation time, that is, the number of times of judgment (judgment material) is small. It is difficult to determine whether the value has exceeded a predetermined value. For this reason, the deterioration state of the ultraviolet phototube cannot be accurately determined, and the inspection reliability of the ultraviolet phototube becomes low.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of controlling a flame detecting apparatus which can improve the reliability of flame detection and the reliability of inspection of flame detecting means. It is to be.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 has a flame detecting means and an inspection means for the flame detecting means. A method for controlling a flame detection device, wherein an operation time when the inspection means is operated at a predetermined time interval is shorter than a non-operation time.

Further, according to a second aspect of the present invention, the flame detecting means is configured to output a detection signal every predetermined operating cycle, and the operating cycle is shortened when the checking means is operating. It is characterized by.

[0012]

Next, an embodiment of the present invention will be described. The present invention is embodied in a flame detection device that detects the state of a flame, particularly, the presence or absence of a flame. This flame detection device is provided in a combustion device such as a boiler, for example, in order to determine whether to continue or stop supplying fuel to the combustion device by detecting the presence or absence of a flame in the combustion device. Used.

The flame detecting device includes flame detecting means, and inspection means for the flame detecting means. The flame detecting means includes an ultraviolet photoelectric tube, a cadmium sulfide cell (CdS
Cell), a light detecting means such as a lead sulfide cell (PbS cell), and detects the flame as light (including visible light and invisible light). The inspection means, during the combustion of the combustion device,
The flame detection means is inspected for a predetermined time at predetermined time intervals.

The inspection means includes a light shielding means for blocking light from entering the flame detection means, and the flame detection means is provided based on a detection signal from the flame detection means when the light shielding means is operated. To determine if is working properly. That is, at the time of the operation of the inspection means, the light shielding means is operated to block the incidence of light on the flame detection means. At this time, if a detection signal indicating no flame is output from the flame detection means, It is determined that the flame detecting means is operating normally. On the other hand, at this time, if a detection signal indicating the presence of a flame is output from the flame detecting means, it is determined that an abnormality has occurred in the flame detecting means. Here, as the light shielding means, for example, there is a shutter mechanism for shielding light by moving an appropriate light shielding body.

[0015] In the control method of the flame detecting device according to the present invention, the operation time of the inspection means is shorter than the non-operation time. That is, the time during which the light shielding means is operating (operating time) is shorter than the time during which it is not operating (non-operating time). Then, the time during which the flame cannot be detected by the flame detecting means is shortened by the operation of the light shielding means, so that the reliability of the flame detection by the flame detecting means is increased.

Further, in the control method of the flame detecting device according to the present invention, the flame detecting means is configured to output a flame detection signal at every predetermined operation cycle, and the operation time of the light shielding means is not activated. It is controlled so as to be shorter than the time and to shorten the operation cycle when the light shielding means is operated. Then, the number of detection signals from the flame detection unit during the operation time of the light-shielding unit increases compared to the case where the operation time of the light-shielding unit is simply shortened, and the abnormality of the flame detection unit is reliably detected. Therefore, the reliability of inspection of the flame detecting means is improved. Further, as described above, since the abnormality of the flame detection means can be reliably detected, the flame detection means can always be operated in a normal state, and the reliability of flame detection by the flame detection means can be improved. Can be even higher.

This control method is particularly suitable for the case where the flame detecting means is a flame detecting means such as an ultraviolet photoelectric tube which outputs a flame detection signal at every predetermined operation cycle. Will be described. First, as described above, the ultraviolet photoelectric tube outputs a predetermined detection signal at each predetermined operation cycle. In addition, the ultraviolet photoelectric tube,
As described above, a detection signal indicating presence of a flame may be output by self-discharge even when no light is incident. The rate of occurrence of this self-discharge increases as the deterioration of the ultraviolet phototube progresses. Therefore, in the flame detection device, the self-discharge occurrence rate is detected as a ratio of the number of detection signals with a flame to the number of detection signals while the light shielding means is operating, and this ratio exceeds a predetermined value. It is determined that the deterioration of the ultraviolet photoelectric tube has reached the use limit.

As described above, self-discharge is a phenomenon that occurs irregularly, and does not always occur at uniform intervals. Therefore, as described above, when the occurrence rate of the self-discharge is detected as the ratio of the number of detection signals indicating the presence of a flame when the light shielding means is operated, in order to accurately detect the occurrence rate of the self-discharge, It is necessary to increase the number of detection signals during time, that is, the number of times of judgment (judgment material). Therefore, as described above, even if the operation time is set to be short, the number of detection signals during the operation time can be increased by shortening the operation cycle at the time of operating the light shielding unit. The occurrence rate of self-discharge can be accurately detected. Therefore, the deterioration state of the ultraviolet phototube can be accurately determined, and the reliability of the inspection of the ultraviolet phototube can be increased.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic explanatory view showing an example of a flame detection device embodying the present invention, and FIG.
FIG. 3 is a bottom view of FIG. 1, and FIG. 3 is an explanatory view schematically showing a time chart of control contents in one embodiment of the present invention. Here, the flame detecting device of this embodiment is a flame detecting device used by being attached to a boiler combustion device. The flame detection device is used to detect the presence or absence of a flame in the combustion device and to control whether to continue or stop supplying fuel to the combustion device.

First, the basic configuration of a flame detecting device embodying the present invention will be described with reference to FIGS. The flame detection device 1 includes a flame detection unit 2, an inspection unit 3 for inspecting an operation state of the flame detection unit 2, and a flame detection unit 2 that controls the flame detection unit 2 and the inspection unit 3 to detect a flame. And control means 4 for checking the flame detection means 2.

The flame detecting means 2 has an ultraviolet photoelectric tube 5 for detecting the flame as light (ultraviolet light). The ultraviolet photoelectric tube 5 is mounted in a cylindrical case 6, and an opening at the tip (lower side in FIG. 1) of the case 6.
The light from the flame is transmitted through the ultraviolet photoelectric tube 5
Is configured to be incident. Then, a driving voltage is applied to the ultraviolet photoelectric tube 5 for a predetermined time for each predetermined operation cycle, and when the driving voltage is applied,
When light from a flame enters the ultraviolet photoelectric tube 5, a detection signal of a predetermined voltage is output as a detection signal of presence of a flame.

The inspection means 3 includes a light shielding means 7 for blocking light from entering the ultraviolet photoelectric tube 5. The light shielding means 7 includes a flat light shielding body 8 that rotates in the horizontal direction below the case 6, and a driving means 9 for the light shielding body 8 disposed on the side of the case 6. . As shown in FIG. 2, the driving means 9 is configured to alternately move the light blocking member 8 between a closed position indicated by a solid line and an open position indicated by a two-dot chain line. That is, the light shielding means 7
Is configured as a so-called shutter mechanism.

When the inspection means 3 is operated, the light shielding body 8 is moved to the closed position by the driving means 9 to cover the opening of the case 6 so that light from the flame can be transmitted to the ultraviolet photoelectric tube. 5 is set to a state where it cannot be incident. When the inspection means 3 is not operated, the driving means 9 moves the light-shielding body 8 to the open position so that light from the flame can enter the ultraviolet photoelectric tube 5 from the opening of the case 6. And

The control means 4 is connected to the ultraviolet photoelectric tube 5 and the driving means 9 via lines 10 and 10, respectively. The control unit 4 controls the application of the driving voltage to the ultraviolet photoelectric tube 5 and controls the operation of the driving unit 9 to check the ultraviolet photoelectric tube 5 and detect the flame by the ultraviolet photoelectric tube 5. And are repeated alternately.

Here, the inspection of the ultraviolet photoelectric tube 5 will be described. The control means 4 moves the light shielding body 8 to the closed position by operating the driving means 9 at predetermined time intervals for a predetermined time. . Then, in a state where the opening of the case 6 is covered by the light shielding body 8, it is determined whether or not the ultraviolet photoelectric tube 5 is operating normally based on the detection signal from the ultraviolet photoelectric tube 5 at this time. That is, when the light-shielding member 8 blocks light from entering the ultraviolet phototube 5 and a detection signal indicating no flame is output from the ultraviolet phototube 5, the ultraviolet phototube 5 is operating normally. Judge. On the other hand, if a detection signal indicating the presence of a flame is output from the ultraviolet photoelectric tube 5, it is determined that an abnormality has occurred in the ultraviolet photoelectric tube 5.

Next, a control method of the flame detecting device 1 will be specifically described with reference to FIGS. First, in the flame detection device 1, a time during which the light shielding means 7 is operated, that is, a time during which the light shielding body 8 is moved to the closed position by the operation of the driving means 9 (hereinafter referred to as "operation time"). A) is set to 0.5 seconds. Further, a time during which the operation of the light shielding means 7 is stopped, that is, a time during which the light shielding body 8 is moved to the open position due to the stop of the operation of the driving means 9 (hereinafter, referred to as a “time”)
B) is set to 2 seconds.

That is, in the flame detecting device 1, the operation time A of the light shielding means 7 is set shorter than the non-operation time B. Therefore, since the time during which the flame can be detected by the ultraviolet photoelectric tube 5 is longer than the time during which the inspection of the ultraviolet photoelectric tube 5 is performed by the inspection means 3, the reliability of the flame detection by the ultraviolet photoelectric tube 5 is high. Become. In addition, since the operating time A is short, even if the flame is extinguished during the operating time A, the flame can be immediately detected as the non-operating time B, and the detection of the misfire is delayed. There is no. Further, by shortening only the operation time A, it is not necessary to increase the number of operations of the driving means 9, and the driving means 9
Can be prevented from being shortened.

Further, in the flame detecting device 1,
As shown in FIG. 3, the operation time A and the non-operation time B
In the above, the operation cycle of the ultraviolet phototube 5, that is, the cycle of applying a driving voltage to the ultraviolet phototube 5, is set as follows. During the operation time A, that is, during the inspection of the ultraviolet photoelectric tube 5, the first operation cycle C is performed during the non-operation time B, that is, while the flame is detected by the ultraviolet photoelectric tube 5, the second operation cycle C is performed. It is shorter than the operation cycle D. When the operation cycles C and D are set in this way, the number of detection signals during the operation time A is increased as compared with the case where the first operation cycle C is set to be the same as the second operation cycle D. be able to. In particular,
The operating cycles C, so that the number of application of the drive voltage during the inspection of the ultraviolet phototube 5 is the same as the number of application of the drive voltage while the flame is detected by the ultraviolet phototube 5. D is set. That is, in this embodiment, since the operation time A is 1/4 of the non-operation time B, the first operation cycle C is set to 1/4 of the second operation cycle D.

When the operating cycles C and D are set as described above, the inspection reliability of the ultraviolet phototube 5 can be increased. Next, the reason will be described.

First, when a driving voltage is applied to the ultraviolet photoelectric tube 5, a phenomenon of outputting a detection signal indicating presence of a flame even when no light is incident, that is, so-called self-discharge may occur. The rate of occurrence of this self-discharge depends on the ultraviolet photoelectric tube 5
Increase as the deterioration proceeds, and eventually occur only by applying a drive voltage. Therefore, in the ultraviolet photoelectric tube 5, the occurrence rate of self-discharge is determined by the operation time A.
Detected as the ratio of the number of detection signals with flame to the number of detection signals in the middle, if this ratio exceeds a predetermined value,
It is determined that the deterioration of the ultraviolet photoelectric tube 5 has reached the use limit.

As described above, self-discharge is a phenomenon that occurs irregularly, and does not always occur at uniform intervals. Therefore, as described above, when the occurrence rate of the self-discharge is detected as the ratio of the number of the detection signals indicating the presence of the flame during the operation time A, in order to accurately detect the occurrence rate of the self-discharge, It is necessary to increase the number of detection signals in A, that is, the number of times of judgment (judgment material).

Therefore, in this embodiment, the operation time A
Is set to be shorter than the non-operation time B, but as described above, by making the first operation cycle C shorter than the second operation cycle D, the number of detection signals during the operation time A is reduced. Is increased until the number of detection signals becomes equal to the number of detection signals during the non-operation time B. Therefore, in this embodiment, although the operation time A is shorter than the non-operation time B, the number of detection signals (the number of determinations) during the operation time A increases, and the occurrence rate of self-discharge decreases. It can be detected accurately. Therefore, the ultraviolet photoelectric tube 5
Can be accurately determined, and the reliability of the inspection of the ultraviolet photoelectric tube 5 can be increased.

Further, the ultraviolet photoelectric tube 5 has such a characteristic that the deterioration proceeds in accordance with the integrated value of the number of discharges, that is, the number of output of the detection signal of the presence of a flame. However, in this embodiment, since the operation time A is set shorter than the non-operation time B and only the second operation cycle D corresponding to the operation time A is shortened, the integrated value Can be suppressed from being greatly increased, which is advantageous in terms of the life of the ultraviolet photoelectric tube 5.

[0034]

According to the present invention, the reliability of flame detection can be enhanced, and the reliability of inspection of the flame detection means can be enhanced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram schematically showing an example of a flame detection device embodying the present invention.

FIG. 2 is an explanatory bottom view of FIG. 1;

FIG. 3 is an explanatory diagram schematically showing a time chart of control contents in one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flame detection device 2 Flame detection means 3 Inspection means A Operation time of inspection means B Non-operation time of inspection means

Claims (2)

[Claims] 1. Flame detecting means 2 and flame detecting means 2
A flame detecting device 1 provided with the above-mentioned inspection means 3, wherein the operation time A when the inspection means 3 is operated at predetermined time intervals is shorter than the non-operation time B. Control method of the detection device. 2. The flame detecting means 2 is configured to output a detection signal every predetermined operating cycle, and when the inspection means 3 operates, the operating cycle of the flame detecting means 2 is shortened. The method for controlling a flame detection device according to claim 1.