JPH0349003B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a flame detection device for determining whether a burner of a combustion device such as a boiler is ignited or extinguished.

[Background of the invention]

Generally, in a combustion device, such as a boiler,
The furnace wall is equipped with a large number of burners, and a given burner is ignited or extinguished depending on the load required of the boiler. In this case, if the burner that should be ignited is not ignited, the desired combustion will not be obtained in the boiler combustion, and this will have an adverse effect on the amount of steam generated and exhaust gas, so each burner is equipped with a flame detection device. By detecting the flame, ignition of the burner is confirmed, and an ignition completion signal is output to the burner control device. Various types of such flame detection devices have been proposed, and one example is an optical flame detection device that outputs a voltage or current depending on the amount of light of the flame.

Conventional flame detection has been performed by determining whether the output voltage or current is equal to or greater than a preset value (trigger value). However, such detection means has the following drawbacks.

(1) Even if a flame detection device installed in a certain burner detects the flame of a burner located opposite or close to that burner in the furnace, the detected value shall be treated as the detected value of the flame of that burner. and prevent accurate flame detection. (Miscatching) (2) Since the amount of light from the flame varies greatly depending on the boiler load and combustion conditions, the trigger value must be constantly readjusted accordingly, but this is extremely difficult in practice.

(3) The reliability of a flame detection device in use can only be determined after a miscatch actually occurs, and cannot be determined in advance.

Due to the above-mentioned drawbacks, the conventional flame detection device has extremely poor reliability, and therefore, the flame detection device itself has become a major factor that significantly lowers the reliability of the burner control device.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to eliminate the above-mentioned conventional drawbacks, eliminate the need to readjust the trigger value even in response to changes in boiler load or combustion conditions, and It is an object of the present invention to provide a flame detection device that can accurately detect flames and improve its reliability.

[Summary of the invention]

In order to achieve the above object, the present invention stores a trigger value for determining the presence or absence of a flame corresponding to each flame detection section for each of various burner patterns of a combustion device, and also stores a trigger value for determining the presence or absence of a flame. The unit stores the current burner pattern, and based on this burner pattern and load information, selects a desired trigger value from among the stored trigger values, and uses the selected trigger value and the flame detection unit to detect the The present invention is characterized in that the presence or absence of a flame is determined by comparing the detected value with the detected value, and the stored trigger value is corrected based on the noise value of the flame detection section.

[Embodiments of the invention]

The present invention will be explained below based on the embodiment shown in FIG.

FIG. 1 is a block diagram of a flame detection device according to an embodiment of the present invention. In the figure, 1 indicates a flame detection section, and 1 ₁ , 1 ₂ , . . . 1 _o are flame detection sections provided in each burner. 2 indicates a preamplifier, 2 ₁ ,
2 ₂ , . . . 2 _o are preamplifiers connected to each flame detection section 1 ₁ , 1 ₂ , . . . 1 _o . 3 is each preamplifier 1 ₁ ,
A multiplexer 4 sequentially switches and outputs the signals of 1 _{2 ,} . 5 is a boiler load signal generator, which outputs information such as the combustion state (size of burner load) in the case of ignition, misfire, or ignition of each burner according to a command. The boiler load signal generator 5 outputs information signals for each burner in synchronization with the multiplexer 3. 6 is boiler load signal generator 6
This is an A/D converter that converts the output signal of the digital signal into a digital signal.

7 is a trigger value calculation/correction unit that calculates and corrects the trigger value to be compared with the flame detection signal of each burner; 8 is a trigger value output from the flame detection signal of each burner and the trigger value calculation/correction unit 7; This is a comparison section that compares the Reference numeral 9 indicates a combustion state storage unit that stores the current combustion state of the burner, that is, the burner pattern; 10 indicates a trigger value storage unit that determines the trigger value of each burner for each burner pattern through experiments or the like and stores this value; 11 1 is a noise value storage unit that stores the noise value of each burner for each burner pattern;
2 is a noise value averaging calculation unit that averages the noise values of each burner. 13 is a signal contact that sequentially switches and outputs the signal from the comparison section 8 for each burner;
4 is an alarm device.

Here, the burner pattern is a combination of predetermined combustion states of each burner, and
The noise value is a detected value when the flame detection section belonging to the misfired burner detects the flame of another burner, that is, at the time of miscatch.

Next, the operation of this embodiment will be explained with reference to the noise value characteristic diagram shown in FIG. Detection signals from the flame detection units 1 ₁ , 1 ₂ , . . . 1 _o of each burner are sequentially outputted from the smoothing unit 4 as a signal a, compared with each other by a comparison unit 8, and outputted as a signal c. Therefore, the signal c is an ignition signal or a misfire signal for each burner, and a burner pattern is obtained by storing this signal in the combustion state storage section 9 for all burners. A pattern signal d corresponding to this burner pattern can be taken out from the combustion state storage section 9 in response to a command.

On the other hand, as load information from the A/D converter 6,
A load information signal b is output according to the magnitude of the burner load in the case of ignition, misfire, and ignition of each burner according to the command. The noise value averaging calculation unit 12
Detection signal a, load information signal b and pattern signal d are input, and in a certain burner pattern obtained by signal d, the detection signal a of the burner when signal b is a misfire signal is input and averaged. do. This averaged value is then output to the noise value storage section 11 as a signal e. Such noise values are shown in FIG. In FIG. 2, time is plotted on the horizontal axis and detection signal is plotted on the vertical axis. When combustion is being performed by a certain burner pattern A, a detection signal a input to the noise value averaging calculation section 12
is not a constant value but changes as shown. The noise value averaging calculation unit 12 calculates the average value of these changing values, and outputs this average value N _A as the noise value of the flame detection unit in pattern A. next,
For example, the extinguishing state of each burner does not change, but the burner load increases and the burner pattern changes to pattern A.
If the pattern changes from to pattern B, the noise value is the value
It becomes N _B. Furthermore, when the noise pattern changes from pattern B to pattern C due to ignition of the burner, the noise value becomes value N _C. Noise value storage unit 1
1 stores the noise value for each flame detection unit in each pattern based on the signal from the noise value averaging calculation unit 12.

The trigger value calculation/correction section 7 inputs the load information signal b of a burner from the A/D converter 6 and the noise value signal f of the flame detection section of the burner from the noise value storage section 11, and also inputs the combustion state signal b. The pattern signal d from the storage section 9 is input, and the trigger value of the flame detection section in the relevant pattern is taken out from the trigger value storage section 10 based on the signal b and the signal d. The extracted trigger value is output to the comparator 8 as a trigger value signal g. On the other hand, since the trigger value has a certain relationship with the noise value, the trigger value calculation/correction section 7 performs necessary calculations based on the value of the noise value signal f, thereby calculating the trigger value. be done. The trigger value previously retrieved from the trigger value storage unit 10 is compared with the calculated trigger value, and if the deviation between the two exceeds a predetermined value, the trigger value stored in the trigger value storage unit 10 is is corrected by the calculated trigger value. Furthermore, the trigger value taken out from the trigger value storage section 10 and the noise value taken out from the noise value storage section 11 are compared, and if the two become abnormally close, the reliability of the flame detection section is It is determined that the temperature has decreased and outputs a signal to the alarm device 14 to issue an alarm.

In the comparator 8, the detection signal a output from the smoothing unit 4 and the trigger value signal g are compared, and the detection signal a is
When the detection signal a is greater than or equal to the trigger value signal g, a flame presence determination signal c is output, and when the detection signal a is less than the trigger value signal g, a flame absence determination signal c is output.
The signal contact 13 is sequentially switched in correspondence with the flame detection section of each burner, and sequentially outputs the determination signal c as a flame detection signal.

In this way, in this embodiment, the trigger value of each flame detection section is stored in advance for each burner pattern,
From the burner pattern signal and the load information signal, a trigger value corresponding to the detection signal of the flame detection section input to the comparison section is extracted, and this trigger value and the detection signal are compared to determine the presence or absence of a flame. Therefore, even if the burner pattern changes due to changes in load or combustion conditions, a trigger value that matches the burner pattern can always be obtained, and there is no need to readjust the trigger value every time the burner pattern changes. Also, based on the burner pattern signal, load information signal, and detection signal, determine the noise value of the flame detection unit in the burner pattern, calculate the trigger value based on this noise value, and compare this trigger value with the stored trigger value. When the deviation of Therefore, the reliability of the flame detection device can be greatly improved.

〔Effect of the invention〕

As described above, in the present invention, a trigger value for each burner pattern is stored, and a required trigger value is selected from the stored trigger values based on the burner pattern and load information. Since the trigger value and the detection value detected by the flame detector are compared, there is no need to readjust the trigger value every time the burner pattern changes. In addition, the noise value is calculated based on the detection value detected by the flame detection section, and the trigger value is corrected based on this noise value, so it is possible to accurately determine the presence or absence of flame, and the flame detection The reliability of the device can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a flame detection device according to an embodiment of the present invention, and FIG. 2 is a characteristic diagram of noise values. 1...Flame detection section, 3...Multiplexer, 4
... Smoothing section, 5 ... Boiler load signal generator, 6 ...
...A/D converter, 7...Trigger value calculation/correction section,
8... Comparison section, 9... Combustion state storage section, 10...
Trigger value storage section, 11...Noise value storage section, 12
. . . Noise value averaging calculation section, 13 . . . Signal contact.

Claims (1)

[Claims] 1: a flame detection section of a burner of a combustion device; a combustion state storage section that stores a burner pattern of the combustion device; a trigger value storage section that stores a trigger value corresponding to the flame detection section for each burner pattern; a load information signal generating section that outputs a load information signal of the combustion device; and a necessary trigger value from the trigger value storage section based on the pattern stored in the combustion state storage section and the load information from the load information signal generating section. a comparison unit that compares the selected trigger value with a detection value detected by the flame detection unit; and a correction unit that corrects the trigger value based on a noise value of the flame detection unit. A flame detection device characterized by being provided.