JPH05240425A - Flame sensing device - Google Patents

Abstract

PURPOSE:To enable a flame sensor to be judged for its normal operation or abnormal operation based on the variation of light amount even at the time of starting normal operation of the burner. CONSTITUTION:In the case that a sensing variation rate W1 of light amount is smaller than a mean variation rate X1, either stain or deterioration of a flame sensor is judged at a judging part 11. On the contrary, in the case that a detection variation rate W4 is smaller than the means variation rate X2 and there is no variation in light volume just after a lost flame is judged, the judgement part 11 judges that the flame sensor shows its burn loss and damage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame detecting device for detecting the presence / absence of a burner flame in a combustion device such as a boiler.

[0002]

2. Description of the Related Art In recent years, with the increase in capacity of boilers, a boiler employing so-called one-side combustion in which a burner is provided only on one side of a front wall or a rear wall is burned on both front and rear walls. Are being converted to boilers that employ so-called opposed combustion in which they are arranged in opposed positions to perform combustion, and since the number of burners has increased to 48 with the increase in capacity of these boilers, burner flames are detected. Flame detection devices are often employed for automatic monitoring by the instrument.

As a flame detecting device in the prior art,
Whether the flame is present or not is detected using a frame rod, or the amount of light of the flame is optically detected to check whether the flame from the burner is ignited or whether the flame from the burner is extinguished. ..

However, in addition to simply detecting the presence / absence of flame, the flame detection device constitutes an automatic combustion control device for a burner in combination with other combustion control devices.
It is also a major factor in determining the quality of the automatic combustion control device.

FIG. 6 is a schematic diagram showing the relative positional relationship between the burner flame and the flame detecting device of a boiler adopting the opposed combustion method, and FIG. 7 is an enlarged view of a conventional flame detecting device in which the essential parts of FIG. 6 are enlarged. is there.

In FIGS. 6 and 7, 1 is a boiler furnace, 2 is a wind box attached to the outer periphery of the boiler furnace 1, 3a and 3b are burners, and 4a and 4b are burners 3.
a flame from a, 3b, 5a, 5b are flame detectors for detecting presence / absence of flames 4a, 4b, 6a, 6b are flames 4a,
Primary combustion zone 4b, 7a and 7b are flame detectors 5a and 5b
Detection ends, 8a and 8b are front and rear walls, and 9a and 9b are burner throats formed in the front wall 8a and the rear wall 8b.

In such a structure, the burner 3a and the flame detector 5a are provided in the burner throat 9a on the front wall 8a side.
A burner 3b and a flame detector 5b are arranged in the burner throat 9b on the rear wall 8b side. The flame 4a of the burner 3a is detected by the detection end 7a, and the flame detector 5b detects the light amount from the primary combustion zone 6b of the burner 4b at the detection end 7b to monitor the flame 4b of the burner 3b. ..

In this way, in the boiler furnace 1, the burners 3a, 3
When b burns together and both flames 4a and 4b exist, the amount of light from the primary combustion region 6b of the opposing flame 4b or the other flame region is incident on the detection end 7a of the flame detector 5a. If flame 4a also exists, flame 4a
The overwhelmingly large amount of light from the opposite flame 4b
a is absorbed and attenuated when passing through the primary combustion zone 4a, the interference of the opposing flame 4b on the flame detector 5a is almost negligible, and therefore the amount of light emitted from the opposing flame 4b by the flame detector 5a is small. By burner 3b flame 4b
The presence or absence of is not erroneously detected or malfunctioned.

[0009]

However, the burner 3
The combustion states of a and 3b do not always form uniform flames 4a and 4b, and the flames 4a and 4b sometimes show flames 4c and 4d as shown in FIG. 7 depending on the nature of the fuel and other external conditions. If either one of the burners 3a and 3b is extinguished due to the
Since the amount of light from the opposing flame is not absorbed or attenuated, the flame detectors 5a and 5b receive the amount of light of the opposing flame to cause erroneous detection and malfunction, which is not preferable.

For example, assume that the burner 3a in FIG. 7 is extinguished and the opposing burner 3b is burning to generate a flame 4b.

In this case, since the opposite burner 3b viewed from the flame detector 5a side is burning, the flame detector 5b is burning the burner 3b according to the amount of light received from the primary combustion region 6b as described above. , But flame detector 5b
The flame detector 5a arranged at the opposite position of the opposite flame 4b
The amount of light from the primary combustion region 6b is received, and this becomes a disturbing signal, which is detected as if the burner 3a is burning even though the burner 3a is extinguished, and erroneous detection and malfunction are repeated.

As described above, since the primary combustion zone 6a of the flame 4a is not formed, the light quantity of the primary combustion zone 6b of the opposed burner 3b is absorbed by the primary combustion zone 6a.
Since it is not attenuated, it is erroneously detected.

Further, when the flame of the burner 3a is shifted from the flame 4a to the flame 4c or the flame of the burner 3b is biased from the flame 4b to the flame 4b, the opposing flame is detected by the opposing flame detector and erroneously detected. , It may malfunction.

The present invention is intended to eliminate the drawbacks of the prior art, and its purpose is to determine whether the flame detector is normal or not by the change of the light quantity, and further, to burner ignition. There is provided a flame detection device capable of determining whether the flame detector is normal or abnormal even during normal operation.

[0015]

In order to achieve the above-mentioned object, the present invention provides at least a light amount change amount immediately before a misfire determination and a light amount change amount immediately after a misfire determination in the vicinity of the photoelectric conversion section. A determination unit for determining whether the flame detector is normal or abnormal by one of them is provided.

[0016]

[Function] By inputting the light amount change amount immediately before the misfire determination and the light amount change amount immediately after the misfire determination to the judgment unit for judging whether the flame detector is normal or abnormal, during normal operation of the burner and when the burner is ignited. Even in this case, it is possible to determine whether the flame detector is normal or abnormal.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a flow chart of a judgment unit during normal operation of a burner according to an embodiment of the present invention, and FIG. 2 is a light amount characteristic curve diagram during normal operation of the burner, in which the vertical axis represents the light amount and the horizontal axis represents time. FIG. 3 is a flowchart of the determination unit at the time of starting the burner, FIG. 4 is a light amount characteristic curve diagram at the time of starting the burner in which the vertical axis represents the light amount and the horizontal axis represents time, and FIG. 5 is a schematic configuration diagram of the flame detection device. ..

In FIGS. 1 to 5, reference numerals 1 to 9 are the same as the conventional ones.

Reference numeral 10 is a photoelectric conversion unit, 11 is a determination unit, and 12
Is a transmission section, 13 is a burner valve, 14, 15, 16, 1
Reference numerals 7, 18, 19, 20, and 21 are comparators.

In such a structure, the burners 3a, 3b
As shown in FIG. 5, the flame detector 5a,
The detection ends 7a and 7b of 5b are arranged. Detection end 7
The amount of light incident on a and 7b is input to the photoelectric conversion unit 10 directly or via an optical fiber cable or the like, and the amount of light is converted into an electric signal such as a voltage and transmitted to the determination unit 11. In the determination unit 11, the flames 4a and 4b are compared with the flame determination reference level.
Whether there is a flame from the subsequent transmission unit 12 to the outside,
Outputs a null signal.

When there is a state lower than the flame learning reference level input to the determination unit 11 for a certain period of time (for example, 5 seconds), it is determined that there is no flame, and the transmission unit 12 outputs a flame no signal to the outside. The automatic combustion control device is not provided, and the burner main valve 13 is closed. Even when making the determination that there is no flame, just before making the determination (for example, 1
The determination unit 11 tries to determine the cause depending on how the light amount of (about 3 minutes ago) or the light amount immediately after the determination is changed and it is determined that there is no flame.

1 and 2, the operation of the determination unit 11 during normal operation of the burner will be described with reference to the flow chart of FIG. 1 and the variation of the light amount will be shown in FIGS.
A description will be given according to (c), (d) and (e).

FIG. 2 is a light quantity characteristic curve diagram when the burner is in normal operation, with the horizontal axis representing time and the vertical axis representing light quantity. 2A shows the time when the flame detectors 5a and 5b determine that there is no flame, and the left side of A in the figure shows the state where the flames 4a and 4b are present.

Therefore, the left side from the time A when the judgment is made shows the change in the light quantity immediately before the misfire judgment is made, and the right side from the time A shows the change in the light quantity immediately after the misfire judgment is made. It can also be determined by the angle θ represented by.

When the gas main valve 13 of FIG. 5 is opened, the detected change rate W of FIG. 1 is detected, and the comparator 14 compares the detected change rate W with the average change rate X ₁ .

Since the detected change rate W _{1 in} FIG. 2A is smaller than the average change rate X ₁ , the determination section 11 determines this detected change rate W 1.
The change in the light amount of ₁ is determined to be due to the dirt and deterioration of the flame detectors 5a and 5b.

That is, the detection change rate W ₁ shown in FIG.
(Time-dependent change in light intensity angle θ) is shown in (b) to (e) of FIG.
Since it is the slowest in comparison with the angle θ, it is determined that the change in the amount of light is due to contamination or deterioration of the flame detectors 5a and 5b.

The detected change rate W _{2 in} FIG.
In is compared to the average rate X _1, is greater than the average rate of change X _1, is input to the comparator 15, the detection rate of change W ₂ is inputted to the comparator 16 is smaller than the average rate of change X _2.
Since there is no flicker of the light amount on the right side of the time A at which the misfire determination is made in FIG.
It is determined that the change in the light amount of ₂ is due to the change in fuel and combustion conditions (the flame detectors 7a and 7b are normal).

It is to be noted that changing the combustion condition depending on the change or load of the fuel in the oil-producing area or the coal-producing area means that the flame detector 5a,
It is also clear by other automatic combustion control devices other than 5b. Since the detected change rate W _{3 in} FIG. 2C is larger than the average change rate X _{1 and} smaller than the average change rate X ₂ , the comparator 16
In, a comparison is made as to whether or not there is a flash of the light amount immediately after time A at which the misfire determination is made.

Immediately after the time point A at which the misfire determination is made in the comparator 16, there is a flare of the light amount, and the difference between the maximum value and the minimum value in the detected change rate W ₃ of the light amount is shown. Since it is large, the determination unit 11 determines that the change in the light amount of the detected change rate W ₃ is due to the fluctuations in the flames 4a and 4b and the fluctuation (the flame detector 5
a, 5b are normal).

Since the detected change rate W _{4 in} FIG. 2D is larger than the average change rate X _2, it is input to the comparator 17 and the presence / absence of the change in light quantity after the misfire determination is compared.

Since there is no change in the light quantity on the right side of time A when the misfire judgment is made in FIG. 2D, the change in the light quantity of the detected change rate W _{4 in} the judging section 11 is due to burning or damage of the flame detectors 5a, 5b. It is determined that it is true (the flame detectors 5a and 5b are abnormal).

Since the detected change rate W _{5 in} FIG. 2 (e) is larger than the average change rate X _2, it is input to the comparator 17, and the comparator 17 compares the presence / absence of the change in the light amount after the misfire determination. ..

Since there is a change in the light quantity on the right side of the time A at which the misfire judgment is made in FIG. 2 (e), the judging section 11 judges that the change in the light quantity of the detected change rate W ₅ is due to the misfire by the burners 3a, 3b. (The flame detectors 5a and 5b are normal).

The normality / abnormality of the flame detectors 5a and 5b can be determined by the angle θ.

The angle θ of the detected change rate W ₁ of FIG. 2A is the smallest as compared with the other angles θ of FIGS. 2B to 2D, and the temporal change of the light amount is the slowest. Flame detector 7
It can be determined that the a and 7b are dirty or deteriorated.

Detected change rates W ₂ and W ₃ shown in FIGS.
The angles θ of the two are almost the same, but the detection change rate W ₃ is larger than the detection change rate W _{2 in} the difference between the maximum value and the minimum value of the light amount, and changes after the time A when the misfire determination is made. Therefore, it can be distinguished from other phenomena.

The detection change rates W ₄ and W _{5 in} FIGS. 2D and 2E.
The angle θ of both is almost the same, but the flame detector 5
In the case of burnout or damage of a and 5b, the time A at which the misfire judgment was made
After that, the light amount does not change (constant), but in the case of misfire, the detected change rate W after the time A when the misfire determination is made.
_{As shown in 5} , there is a change in light intensity, which is distinguishable from other phenomena.

3 and 4, the operation of the determination unit 11 when the burner is ignited will be described with reference to the flow chart of FIG.
A description will be given according to (c).

4 (a), (b) and (c) show changes in the light amount when the burners 3a and 3b are ignited. The vertical axis shows the light amount, the horizontal axis shows the time, and the horizontal axis shows B is the time when the burner valve 13 started to open, and C on the horizontal axis is the flame detector 5.
Time when a and 5b detected no flame and started abnormal extinction, δ
Indicates the angle represented by the change amount / time of the light amount immediately before time C when abnormal fire extinguishing starts.

In FIG. 3, the detected change rate Z for 10 seconds before the misfire determination is detected, and the comparator 18 determines whether or not the detected change rate Z is zero.

When the detected change rate Z is zero, the determination unit 11 has no detected change rate W, and therefore it is determined that the burners 3a and 3b have failed to ignite or the flame detectors 5a and 5b have failed. Since the detected change rate Z _{1 in} FIG. 4A is smaller than zero, it is input to the comparator 19, which compares the detected change rate Z ₁ with the average change rate Y ₁ during normal ignition.

Since the detected change rate Z ₁ is larger than the average change rate Y ₁ , the determination unit 11 determines that the change in the light amount of the detected change rate Z ₁ is due to the contamination or deterioration of the flame detectors 5a and 5b. Further, the light amount at the time of ignition is increasing (on the contrary, it is decreasing when viewed from the time when abnormal fire extinguishing is started), and it can be determined by the angle δ which is represented by 1 hour of change in light amount immediately before time B when abnormal fire extinguishing is started. If the angle δ is negative and small, or there is no change in the angle δ, the burners 3a and 3b have failed to ignite, or the flame detectors 5a and 5b have become dirty or deteriorated.
The detected change rate Z _{1 in} (a) shows this.

Since the detected change rate Z _{2 in} FIG. 4B is smaller than the average change rate Y _{1 and} larger than the average change rate Y _2, it is input to the comparator 20, and this comparator 20 outputs the detected change rate Z ₂ . The average rates of change Y ₂ are compared.

Since the detected change rate Z ₂ is larger than the average change rate Y ₂ , in the judgment section 11, the change in the light amount of the detected change rate Z ₂ ignites the burners 3a, 3b and the flame detectors 5a, 5b.
In b, the flame was detected, but the flame did not become present due to lack of time, and it is determined that the burner automatic combustion device (not shown) failed or the ignition was delayed.

The angle δ in FIG. 4B is negative and large, and the burners 3a and 3b ignite, but the flame detector 5
The detected change rate Z _{2 in} FIG. 4B shows this when the flames a and 5b do not become flamed due to the time lag.

Since the detected change rate Z _{3 in} FIG. 4 (c) is larger than the average change rate Y _2, it is input to the comparator 21. Since the detected change rate Z ₃ is smaller than zero in this comparator 21, the determination unit In 11, the change in the light amount of the detected change rate Z ₃ is
It is determined that flames 4a and 4b are blown off, although a and 3b are temporarily ignited.

Further, the angle δ in FIG. 4 (c) is a positive value, which is the case where the ignition is temporarily ignited but then blown off. The detected change rate Z _{3 in} FIG. 4 (c) shows this. There is.

[0050]

According to the present invention, the abnormality of the flame detector can be judged by the change of the light quantity, and further, the judgment can be made even during the normal operation of the burner or at the start-up.

[Brief description of drawings]

FIG. 1 is a flowchart of a determination unit during normal operation of a burner according to an embodiment of the present invention.

FIG. 2 is a light amount characteristic curve diagram during normal operation of the burner, in which the vertical axis represents the light amount and the horizontal axis represents time.

FIG. 3 is a flowchart of a determination unit when the burner is activated.

FIG. 4 is a light amount characteristic curve diagram when the burner is started, in which the light amount is plotted on the vertical axis and the time is plotted on the horizontal axis.

FIG. 5 is a schematic configuration diagram of a flame detection device.

FIG. 6 is a schematic configuration diagram showing a relative positional relationship between a burner flame and a flame detection device of a boiler adopting an opposed combustion method.

FIG. 7 is an enlarged view of a conventional flame detection device in which a main part of FIG. 6 is enlarged.

[Explanation of symbols]

 3a burner 3b burner 4a flame 4b flame 5a flame detector 5b flame detector 10 photo / electric conversion unit 11 determination unit

Claims (1)

[Claims] 1. A two or more burners that form flames at different positions, a flame detector that detects the amount of light from the burner flame, and the amount of light detected by the flame detector, which is transmitted as an electrical signal. A light / electric conversion unit for converting and detecting the presence / absence of a burner flame based on the amount of light, the amount of change in the amount of light immediately before the misfire determination is made in the vicinity of the light / electric conversion unit and immediately after the misfire determination. A flame detection device comprising a determination unit for determining whether the flame detector is normal or abnormal based on at least one of the light intensity change amounts.