JPH0490413A - Detecting method for flame - Google Patents

Abstract

PURPOSE:To decide the combustion or shutdown of its own burner accurately by judging the combustion or flame failure of the burner on the basis of the signal of a high-frequency component from a sensor during the combustion operation of the burner, giving a constant threshold to the difference between the signals of the high-frequency component and a low-frequency component during the suspension of the shutdown of the burner and deciding whether or not the burner is brought to the state of actual shutdown. CONSTITUTION:A switch 9 is turned OFF and an evaluating signal 10 output from a subtracter 8 is left as a signal 6 corresponding to the high-frequency component of a photosensor 6 during the combustion operation of its own burner. A discriminator 11 outputs a decision signal 12 displaying bringing under the state of combustion of its own burner when the evaluating signal 10 exceeds a threshold, and outputs a decision signal 12 displaying shutdown instantaneously when the evaluating signal 10 is made smaller than the threshold. The switch 9 is turned ON, the state of the burner is detected on the basis of the signal 6 of the high-frequency component and the signal 7 of the low-frequency component of a photosensor 2 and the difference of the intensity of the signals 6, 7 of both components is output as the evaluating signal 10 from the subtracter 8 during the suspension of the shutdown of its own burner. The discriminator 11 outputs the decision signal 12 displaying bringing under the state of actual shutdown of the burner when the intensity of the evaluating signal 10 is made smaller than the threshold, and outputs a decision signal 12 displaying bringing under the state of combustion when the intensity of the evaluating is made larger than the threshold.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical flame detection method for detecting burning and extinguishing of a burner, and in particular, the present invention relates to an optical flame detection method for detecting burner combustion and extinguishing. The present invention relates to a flame detection method that can prevent misidentification.

[Prior art] To determine whether or not burners installed in industrial furnaces, boilers, etc. A flame detection method is employed.

Conventionally, in this type of flame detection method, the presence or absence of a burner flame is determined by detecting synchrotron radiation using a light globe installed near the burner and detecting a sudden change in brightness when the burner is ignited. is common.

[Problem to be solved by the invention] By the way, when a large number of burners are installed in the same furnace, it is difficult to place the burners in opposite positions! Alternatively, other burners may be present at adjacent locations. Therefore, the field of view of the light globe is
This means that not only the light of the own burner's flame to be detected but also the light of other burner flames will enter.For example, if another burner is installed in a position opposite to the own burner, Even if the burner is extinguished, the optical probe will detect the light from the tip of the burner flame located opposite to it. Since the brightness of the burner flame is brighter at the tip than at the base (ignition), there is a problem that when the burner flame at the opposite position is detected by the light globe, it is easily mistaken as the ignition state of the own burner. Ta.

An object of the present invention is to solve the above-mentioned problems, and to provide a flame detection system that can clearly distinguish between the light of the own burner flame to be detected and the light of other burner flames, and that can accurately determine whether the own burner is burning or extinguishing. The purpose is to provide a method.

[Means for Solving the Problem] In order to achieve the above object, the present invention converts fluctuations in the brightness of light emitted from the flame of a burner into an electrical signal using an optical sensor, and controls the combustion of the burner based on the signal.・In the flame detection method for determining extinguishment, ``the signal from the sensor is extracted into a high frequency signal and a low frequency signal, and during the combustion operation of the burner, the burner's combustion signal is determined based on the signal of the high frequency component. When a misfire is determined and the burner is not extinguished,
The difference between the signals of the high frequency component and the low frequency component is set to a certain threshold value to determine whether or not the burner is actually extinguished.

[During combustion operation of the active coburner, combustion/misfire is determined by detecting a signal of a high frequency component among the fluctuating components of the brightness of the burner flame. The high-frequency component signal is large when the burner to be detected is burning, and small when the burner is burning other burners, so when the signal becomes small, it can be immediately detected that the burner is misfiring.

While the burner is not extinguished, signals of a high frequency component and a low frequency component among the luminance fluctuation components are detected.

The low-frequency components that should be detected are small when the burner is burning, but large when other burners are burning, so by detecting the degree of these signals, it can be determined whether or not the burner is actually extinguished. can do. At this time, by setting a certain threshold value to the difference between the signals of both components, even if there is fluctuation in the detection signal, the determination can be made more reliably.

[Example] Next, one embodiment of the present invention will be described.

FIG. 1 shows the configuration of a detection system for implementing the flame detection method according to the present invention. In the figure, 2 is an optical sensor,
A high frequency band filter 4 and a low frequency band filter 5 are connected to the optical sensor 2 .

A subtracter 8 is connected to the output end of these filters 4.5, and a determiner 11 is connected to the output end of the subtracter 8.

A switch 9 is provided between the low frequency band filter 5 and the subtracter 8.

A detection system is provided for each individual burner.

The optical sensor 2 is provided near the burner to be detected, and has a field of view 1 that allows it to see through from the base end (ignition part) to the tip of the flame of the burner. This optical sensor 2 is configured to convert fluctuations in the brightness of radiation from a burner flame into an electrical signal 3 and output the electrical signal 3.

When the electrical signal 3 is output from the optical sensor 2, the high frequency band filter 4 filters out the high frequency component (50
~500Hz) is extracted and output. On the other hand, the low frequency band filter 5 extracts and outputs only the low frequency component (0.1 to 10 Hz) signal 7 from among the luminance fluctuation components.

The subtracter 8 is a 0 determiner 11 configured to output the intensity difference obtained by subtracting the output signal 7 of the low frequency band filter 5 from the output signal 6 of the high frequency band filter 4 to the determiner 11 as an evaluation signal 10. The threshold value of the combustion state of its own burner is inputted together with the evaluation signal 10, and the evaluation signal 10 and the threshold value are compared to output a combustion/extinguishing determination signal 12. ing.

Next, a flame detection method using the above detection system will be explained.

When many burners are installed in the same furnace, high frequency components (50 to 500
Hz) tends to be large for combustion in the own burner to be detected and small for combustion in other burners. Conversely, among the fluctuation components of the brightness of the burner flame, the low frequency components (0,1 to 1
0 Hz) tends to be small for combustion in the own burner to be detected and large for combustion in other burners.

Therefore, during the combustion operation of the own burner, the switch 9 is turned off, and the evaluation signal 10 output from the subtracter 8 is left as the signal 6 corresponding to the high frequency component (50 to 500 Hz). The determiner 11 outputs a determination signal 12 indicating that its own burner is in a combustion state when the evaluation signal 10 is equal to or higher than a threshold value, and immediately outputs a determination signal 12 indicating that its own burner is in a combustion state when the evaluation signal 10 becomes smaller than the threshold value. A determination signal 12 indicating a burner misfire is output.

Next, turn on switch 9 while your own burner is not extinguished.
High frequency components (50 to 500 Hz> signal 6)
The state of the burner is detected based on the low frequency component (0.1 to 10 Hz) signal 7. The subtracter 8 outputs the difference in intensity between the two component signals 6 and 7 as an evaluation signal 10. When the evaluation signal 10 is input, the determiner 11 outputs a determination signal 12 indicating that the burner is actually in the extinguished state when the intensity of the evaluation signal 10 is smaller than the threshold; is larger than the threshold value, a determination signal 12 indicating that the burner is in the combustion state is output. In this way, by setting a certain threshold for the intensity difference between the signals 6.7 of both components, even if there is fluctuation in the detection signals 6.7 of both components, it can be mistaken for combustion/extinguishing of another burner. It is possible to reliably determine whether or not your own burner is burning or extinguishing.

[Effects of the Invention] In summary, according to the present invention, it is possible to prevent misidentification between the light of the own burner flame to be detected and the light of other burner flames, and to accurately determine whether the own burner is burning or extinguishing. You can achieve excellent results.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a detection system for implementing the flame detection method according to the present invention. In the figure, 2 is an optical sensor, 6 is a high frequency component signal, and 7 is a low frequency component signal.

Claims (1)

[Claims] 1. In a flame detection method in which fluctuations in the brightness of light emitted from the flame of a burner are converted into an electrical signal by an optical sensor, and based on the signal it is determined whether the burner is burning or extinguishing, the signal from the sensor is converted into a high frequency signal. During the combustion operation of the burner, combustion/misfire of the burner is determined based on the signal of the high frequency component, and while the burner is not extinguished, the high frequency component and the low frequency signal are extracted. A flame detection method characterized in that it is determined whether or not the burner is actually in an extinguished state by setting a certain threshold value to the difference between signals of frequency components.