JP3365535B2 - Combustion equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a plurality of burners arranged in parallel, detects the combustion state of each burner with a flame rod or the like, and stops the combustion when an abnormal combustion state is caused by a decrease in the air amount. The present invention relates to the improvement of the combustion device.

[0002]

2. Description of the Related Art Conventionally, in this type of combustion apparatus, a CO (carbon monoxide) sensor is installed at a distance from a flame group as a method for accurately detecting normal / abnormal combustion conditions. There are known methods for measuring CO concentration and for measuring burner temperature and flame temperature by installing a thermocouple in the vicinity of the flame group. There is also known a method of detecting a flame current of some burners using a frame rod (see Japanese Utility Model Publication No. 62-5551).

[0003]

By the way, the method for measuring the above-mentioned CO concentration is described below.
It is difficult to obtain a highly accurate CO concentration measurement value because the measurement value varies depending on the installation position of the sensor.

Regarding the method of measuring the burner temperature and flame temperature with a thermocouple, the thermocouple cannot be installed too close to the flame from the viewpoint of the durability (heat resistance) of the thermocouple itself. Moreover, it is still difficult to obtain an accurate temperature measurement value.

Further, in the flame current detecting method disclosed in the above publication, since there is no problem in durability (heat resistance) of the frame rod itself, the flame rod can be installed so as to face the flame outlet of the burner. Since the absolute value of the detected flame current is small, it is easily affected by disturbance such as noise, and it is difficult to obtain an accurate flame current measurement value.

Therefore, an object of the present invention is to improve the detection accuracy of the flame current value in a combustion apparatus that determines the normal / abnormal combustion state of a plurality of burners arranged in parallel by detecting the flame current of some burners. It is to provide a combustion device capable of performing the above.

[0007]

A combustion apparatus according to a first aspect of the present invention has a plurality of burners arranged in parallel, and is inserted into the flame of a part of the burners in each of the above burners to obtain a flame current. The flame current detection means for detecting the, and a determination means for determining whether or not abnormal combustion based on the flame current detection, the installation interval between the burners, at least flames of different burners during normal combustion are mutually The distance is set such that the flames of different burners do not come into contact with each other during abnormal combustion and the flames of the different burners may contact each other, and the determination means determines abnormal combustion when the flame current exceeds a predetermined threshold value.

A combustion apparatus according to a second aspect of the present invention has a plurality of burners arranged in parallel, and a state quantity detecting means for detecting a state quantity that changes according to the degree of contact between flames of the burners. And a determination means for determining whether or not the combustion is abnormal based on the state quantity detection of the flame, the installation interval between the burners, flames of different burners do not contact each other at least during normal combustion, and, The distance is set so that the flames of the different burners may come into contact with each other during abnormal combustion, and the determination means determines abnormal combustion when the state quantity of the flame exceeds a predetermined threshold value.

According to the first aspect of the present invention, the installation intervals between the burners are such that at least flames of different burners do not contact each other during normal combustion, and flames of different burners contact during abnormal combustion. Is set to a distance that can occur, and it is determined that abnormal combustion occurs when the detected flame current value exceeds a predetermined threshold value, so that the absolute value of the detected flame current can be increased, The accuracy of detection of flame current value does not deteriorate due to the influence of noise and the like.

According to the second aspect of the present invention, the installation intervals of the burners are such that flames of different burners do not contact each other at least during normal combustion, and flames of different burners contact during abnormal combustion. Is set to a distance that can occur, and since it is determined that abnormal combustion occurs when the detected flame state amount exceeds a predetermined threshold value, it is possible to increase the detected flame state amount. The accuracy of detecting the state quantity of flame does not deteriorate due to the influence of noise or the like.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing a combustion apparatus according to an embodiment of the present invention.

In the above apparatus, the external air suction fan 1, the air supplied from the fan 1 is used as a primary air for forming an air-fuel mixture together with the fuel gas, and as a secondary air for supplementing oxygen separately from the burner. The air introduction part 3 introduced to the side and the metal body 5 provided on the outer wall surface of the air introduction part 3 are provided. In the above device, the base end portions are connected to the metal body 5 at a predetermined interval from each other, and each air-fuel mixture inlet (not shown)
Is also provided with a plurality of burners 7 to 15 which are respectively in communication with the air introduction part 3 and the gas manifold (not shown).

In the above apparatus, the frame rod 19, which is supported by the insulating member 17, and the flame rod 19 for detecting the flame which faces the flame outlet of the burners 7, 9 and the flame 21 blown from the burners 7, 9 are used. 9. A resistor 23 and a transformer 25 forming a closed loop for passing a frame rod current (FR current) together with the metal body 5 are also provided. The above-mentioned device also inputs a voltage signal generated in the resistor 23 and indicates threshold values (a first threshold value Th1, a second threshold value Th2, a reference value, and the like, which will be described later) for determining whether or not there is an abnormal combustion state. , Which is determined for each number of combustion amounts. The same applies hereinafter), and a comparator 27 for determining whether the combustion is abnormal due to a decrease in oxygen concentration is also provided. The device further includes a solenoid valve (not shown) for disconnecting / connecting between the gas source (not shown) and the gas manifold when an electric signal indicating that abnormal combustion has been determined is output from the comparator 27. And a gas control device 29 for closing combustion and stopping combustion.

In the present embodiment, the installation intervals 33 of the burners 7 to 15 are such that the flames 21 do not contact each other at least when the burners 7 to 15 are normally burning, and
The distance is set such that the degree of contact between the flames 21 increases as the flame width increases with the increase of the CO concentration value (transition to the abnormal combustion state). This distance is for each burner 7
It is not possible to unambiguously determine the size of the flame 21 blown out from each of the above-mentioned burners (the size of the flame is affected by the structure of the burner and the type of gas used as the fuel gas). In 7 to 15, it is set to the extent that the fire transfer does not deteriorate.

Further, the burners 7 to 15 are provided at the portions of the air introducing portion 3 and the metal body 5 corresponding to the above-mentioned installation intervals 33, respectively.
On the other hand, the secondary air introduction holes 41 necessary for introducing the secondary air for supplementing oxygen are formed respectively.

FIG. 2 is a characteristic diagram showing the relationship between the FR current value and the CO concentration value described above.

In FIG. 2, the curve 1 shows the change in the FR current value obtained by the contact of all the flames blown out individually from all the burners, and the curve 2 is blown out individually from each burner. The change in the FR current value obtained by the flame is shown.

As is clear from the figure, the FR shown by curve 2
The current value decreases as the CO concentration value increases,
When the concentration value becomes equal to or higher than the value indicated by the symbol E0 (that is, the value indicating the abnormal combustion state), the FR current value becomes equal to or lower than the second threshold value (Th2) indicating the abnormal combustion state. On the other hand, the FR current value indicated by the curve 1 increases as the CO concentration value increases, and when the CO concentration value reaches the above value E0, the FR current value indicates the abnormal combustion state as indicated by the point A. 1 threshold (T
h1) is reached. When the CO concentration value further increases (that is, the abnormal combustion state becomes more severe) to reach the concentration E1, the FR current value becomes maximum, and when it further increases from the concentration E1, it starts to decrease. When the CO concentration value increases to the concentration E2, the FR current value decreases to the first threshold value (Th1) as shown by the point B, and when the CO concentration value further increases, the FR current value changes to the first value. It is less than the threshold value (Th1).
That is, when the abnormal combustion state becomes extremely severe, the FR current value becomes lower than the first threshold value (Th1).

As described above, the reason why the FR current value shown by the curve 1 also increases with the increase of the CO concentration value toward the concentration E1 is that the flame from each burner changes from normal combustion to abnormal combustion. It is considered that the flames gradually spread and the flames contact each other. Therefore, in the case of a combustion device in which a plurality of burners are arranged in parallel at a predetermined interval as in the present embodiment, the FR current value shown by the curve 1 is increased in the region of the concentration E1 or less as the CO concentration value increases. When the CO concentration value increases and becomes equal to or more than the above value E0, it becomes equal to or more than the first threshold value (Th1). Therefore, the absolute value of the FR current for detecting whether the combustion state is abnormal can be increased. Therefore, it is possible to improve the detection accuracy of the abnormal combustion state.

Next, the control operation of the above configuration will be described with reference to the flowchart of FIG.

Based on the output signal from the comparator 27, the gas control device 29 first determines whether or not the combustion device is burning (step S1). As a result, when it is determined that the combustion is being performed, it is next determined whether the variation of the combustion amount is within ± 1 or not, that is, whether the combustion stable condition is satisfied (step S2). As a result, when the variation of the combustion amount is within ± 1, it is determined that the stable condition of combustion is satisfied, and the process shifts to the check of the FR current flowing through the closed loop described above (step S3).

That is, the comparator 27 determines whether or not the FR current value exceeds the reference value (that is, the first threshold value Th1 in FIG. 2). As a result, when it is determined that the combustion time has exceeded, it is determined that the combustion state is abnormal, and the combustion stop control such as the closing operation of the solenoid valve (not shown) is performed by the gas control device 29 (step S4). And
The occurrence of abnormal combustion is notified by driving an alarm buzzer (not shown) or an indicator (step S
5).

As described above, according to this embodiment, the installation intervals 33 of the burners 7 to 15 are set so that the flames 21 do not come into contact with each other at least when the burners 7 to 15 are normally burning. Further, since the distance is set such that the degree of contact between the flames 21 increases as the flame width increases with the increase of the CO concentration value, the FR current for determining whether the combustion state is abnormal or not. The absolute value of can be larger than the conventional one. Therefore, the influence of disturbance such as noise is less likely to occur, and it is possible to accurately determine whether the combustion state is abnormal.

FIG. 4 is a flowchart according to the first modification of the above embodiment.

In this modification, steps S11 to S13 are performed.
3 performs the same processing as steps S1 to S3 in FIG. 3, and when it is determined in step S13 that the FR current exceeds the reference value (threshold Th1 in FIG. 2), the combustion stop control is not immediately performed, and the rotation speed of the fan 1 is changed. Increase 100 rpm to increase the air volume to each burner 7-15 (step S1).
4). This is because the cause of abnormal combustion is usually due to lack of air (lack of oxygen), so it is often resolved by increasing the air volume.

After performing the process of step S14,
It is determined whether or not the stable condition of combustion (that is, the state where the fluctuation of the combustion amount is within ± 1) is satisfied (step S15), and if the stable condition is satisfied, FR is again displayed.
It is determined whether the current value exceeds the reference value (step S
16). As a result, if it exceeds the reference value, the fan rotation speed is increased by 100 rpm (step S14) until the rotation speed of the fan 1 is determined to be 500 rpm or more (step S17), and an attempt is made to eliminate the abnormal combustion state. (That is, the processing operations of steps S14, S15, S16, and S17 are repeated).

However, even if the fan rotation speed is increased to increase the air flow rates to the burners 7 to 15 as described above, the abnormal combustion state is not eliminated and the fan rotation speed becomes 500 rpm or more (steps S16 and S17). ), The same combustion stop control as in step S4 of FIG. 3 is performed (step S18), and then the same abnormality notification as in step S5 of FIG. 3 is performed (step S19).

On the other hand, when the FR current value becomes less than the reference value due to the increased air volume (step S16), the increase amount of the fan rotation speed in step S14 is stored in the memory (not shown) in the gas control device 29. And so on (step S20).

In this modified embodiment, the same effect as in the above-described one embodiment is obtained, and when the abnormal combustion state is eliminated by increasing the air flow rate to each burner 7-15, the combustion is continued. Therefore, the usability of the device can be improved.

FIG. 5 is a flow chart according to the second modification of the above-mentioned one embodiment.

In the present modification, in view of the fact that there is the characteristic of FIG. 2 between the FR current value and the CO concentration value, the change in the FR current value when the fan speed is increased is checked to check for an abnormal combustion state. It was decided to judge the lightness and weight of. That is,
This is because it is difficult to grasp whether or not the combustion state is normal or to grasp the degree of abnormal combustion state by simply detecting the FR current value indicated by the curve 1. In this modification, if it is determined that abnormal combustion is mild as a result of the above check, an attempt is made to eliminate the abnormal combustion state by increasing the fan rotation speed, and if it is determined that abnormal combustion is severe, the fan rotation speed is increased. However, since the abnormal combustion state cannot be resolved, combustion stop control is performed.

In FIG. 5, when it is confirmed that the combustion device is in the process of combustion (step S31) and the above-described stable condition of combustion is satisfied (step S32), first, the fan rotation speed is increased by 100 rpm to burner. The amount of air supplied to is increased (step S33). After confirming again that the stable combustion condition is satisfied (step S34), it is checked whether or not the FR current has decreased (step S35).

As a result of this check, if the FR current value has not decreased, the CO concentration value exists in the region on the right side of the concentration E1 in FIG. 2, indicating that the abnormal combustion state is severe. When this is seen in FIG. 6 showing the relationship between the FR current value and the air flow rate value to the burner, the air flow rate value exists in the region on the left side of the point H, and the air flow rate is small to eliminate the abnormal combustion state. 6 (corresponding to point B in FIG. 2 and point C in FIG. 6 corresponds to point A in FIG. 2). Therefore, in this case, the combustion stop control is immediately performed (step S36), and the abnormality notification is also performed (step S37).

On the other hand, as a result of the above check, if the FR current value has decreased (step S35), the CO concentration value is as shown in FIG.
6 exists in the area on the left side of the concentration E1 and in the area on the right side of the point H in FIG. 6, indicating that the abnormal combustion state is mild. Therefore, in this case, it is checked whether or not the FR current value exceeds the first threshold value (Th1) (step S38), and the abnormal combustion state is mild even if it is determined that the FR current value exceeds the first threshold value (Th1). Until it is determined that the rotation speed is 500 rpm or more (step S39), the fan rotation speed is increased by 100 rpm (step S33) to try to eliminate the abnormal combustion state (that is, steps S33, S34, S35, S38, S39).
Repeat the processing operation of). Then, when it is determined that the FR current value has become less than the first threshold value (Th1) (step S38), it is determined that the abnormal combustion state has been eliminated, and the control operation ends.

However, even if the fan rotation speed is increased by 100 rpm to increase the air volume to the burners 7 to 15 (step S33), the FR current value does not become less than the first threshold value (Th1), and the fan rotation speed is reduced. When the speed is 500 rpm or more (steps S38 and S39), the combustion stop control is performed (step S36), and then the abnormality notification is performed (step S37).

In this modification, the same effects as those of the above-described embodiment and the first modification thereof are obtained, and the change of the FR current value when the fan speed is increased is checked to reduce the weight of the abnormal combustion state. Since the determination is made, when the abnormal combustion state is slight, it is possible to eliminate the abnormal combustion state by not performing the combustion stop control immediately but by increasing the fan rotation speed.

FIG. 7 is a flow chart according to the third modification of the above-mentioned one embodiment.

The control operation of this modification is basically the same as the control operation of the second modification. However, after it is determined that the combustion is in progress (step S51) and that the combustion stability condition is satisfied (step S52), it is checked whether or not the FR current value exceeds the threshold value (TH1) (step S53). ), The main feature of this modification is to perform control (step S54 and subsequent steps) to increase the fan rotation speed only when it is determined that the number of rotations exceeds the limit.

That is, the fan speed is increased by 100 rpm (step S54), and it is reconfirmed that the stable combustion condition is satisfied (step S55), and then it is checked whether the FR current has decreased (step S55). S56). If the result of this check is that the FR current value has not decreased, combustion stop control is immediately performed (step S57), and anomaly notification is also performed (step S58).

On the other hand, as a result of the above check, if the FR current value has decreased (step S35), it is checked whether or not the FR current value has reached its initial value (that is, a value indicating an ideal combustion state). Then, (step S59), until it is determined that the rotation speed of the fan 1 is 500 rpm or more (step S60), the fan rotation speed is increased by 100 rpm (step S54), and the FR current value is tried to become the initial value (that is, , Steps S54, S55, S56, S59, S
The processing operation of 60 is repeated). When it is determined that the initial value has been reached (step S59), the control operation is terminated assuming that the normal combustion state has been entered. But,
Even if the fan rotation speed is increased by 100 rpm (step S54), the FR current value does not reach the initial value and the fan rotation speed becomes 500 rpm or more (step S5).
9, 60), the combustion stop control is performed (step S57),
Then, the abnormality is notified (step S58).

In this modification, the same effect as in the second modification can be obtained.

FIG. 8 is a block diagram of essential parts of a combustion apparatus according to another embodiment of the present invention.

In the above apparatus, a plurality of burners are divided into a basic burner group 71 that is always used during combustion, and an extended burner group 73 that is used in addition to the basic burner group 71 if necessary, and a normal / abnormal combustion state is obtained. Frame rod 7 for detecting
The main feature of the configuration is that No. 5 is installed so as to detect flames of all the burners on the basic burner group 71 side. In the above device, the basic burner group 71 for the fuel gas supplied from the gas supply source (not shown) through the proportional valve 77.
On-off valve 79 for controlling inflow to the side, expansion burner group 7
The 2nd on-off valve 81 which controls the inflow to the 3 side is provided.
The installation interval between the basic burner group 71 and the extended burner group 73 is set so that the width of the flame 83 on the burner group 71 side during abnormal combustion,
The width of the flame 85 on the side of the burner group 73 is widened and set to a distance at which they can be electrically connected to each other.

In the above structure, normally, at the time of ignition or when the required combustion amount is small, only the first opening / closing valve 79 is opened to burn only the basic burner group 71, and when the required combustion amount increases above a certain level, The second opening / closing valve 81 is also opened to burn the expanded burner group 73 together with the basic burner group 71. When only the basic burner group 71 is burned, the FR current value decreases when these are in an abnormal combustion state. On the other hand, when both the basic burner group 71 and the extended burner group 73 are burning together, if they become an abnormal combustion state,
Since the width of the flame 83 on the side of the burner group 71 and the width of the flame 85 on the side of the burner group 73 expand and come into contact with each other,
The FR current value of all burners increases.

Therefore, when only the burner group 71 burns, the first and second thresholds for determining whether the FR current detection value is normal or abnormal in the combustion state (these thresholds are also as described above). (Determined for each number of combustion amount), it is judged as an abnormal combustion state when it falls below the smaller threshold value of the first type, and when burning both burner groups 71 and 73, the larger one is burned. It was decided that the combustion state was abnormal when the two thresholds were exceeded.

Next, the control operation of the above configuration will be described with reference to the flowchart of FIG.

In FIG. 9, after it is determined that the combustion is in progress (step S91) and that the stable combustion condition is satisfied (step S92), the first on-off valve 79 and the second on-off valve 81 are open. Whether (that is, whether both burner groups 71 and 73 are burning together) is checked (step S9).
3). As a result of this check, if the second opening / closing valve 81 is closed, only the basic burner group 71 will be burned, so it is necessary to determine whether or not there is an abnormal combustion state by using the first type threshold value. Become. That is, when it is determined that the FR current value is below the first type threshold value (step S94), the combustion stop control is performed (step S95) and the abnormality notification is also performed (step S96).

On the other hand, when the result of the check in step S93 is that the second on-off valve 81 is open, it means that both burner groups 71, 73 are combusting, so there is an abnormal combustion state. The determination as to whether or not to do so is performed using the second type threshold value. That is, the FR current value is the second
When it is determined that the value exceeds the seed threshold value (step S97), the second opening / closing valve 81 is closed and the subsequent opening operation of the second opening / closing valve 81 is prohibited (step S9).
8). As a result, after step S98, only the basic burner group 71 is burned, and steps S91, S
The processing operations of 92, S93, and S94 are performed.

Also in this embodiment, as in the above-described embodiment, when the degree of abnormal combustion is relatively small, the combustion stop control is not immediately performed, and the fan speed is increased according to the degree. It is also possible to try to eliminate the abnormal combustion state by making a notification that abnormal combustion is occurring when the abnormal combustion state cannot be eliminated.

FIG. 10 is a block diagram of a main part of a combustion apparatus according to the third embodiment of the present invention.

In this embodiment, the CdS resistor 101 is used as an optical sensor, and the flame 107, between the burners 103, 105,
The CdS resistor 101 as shown in FIG.
Flames 107, 109 utilizing O concentration value (ppm) characteristics
This is to detect the contact between them. That is, C
When the width of the flames 107, 109 is widened by the increase of the O concentration value and the flames come into contact with each other, these flames 107, 1
Since the amount of light emitted from 09 increases and the resistance value of the CdS resistor 101 decreases, it can be seen that an abnormal combustion state has occurred.

According to the present embodiment, even if the CdS resistor 101 is installed at a location separated from the flames 107 and 109, the accuracy of detecting the contact between the flames 107 and 109 can be improved.

FIG. 12 is a block diagram of the essential parts of the combustion apparatus according to the fourth embodiment.

In this embodiment, the thermocouple 111 serving as the temperature sensor is connected to the flames 117, 1 between the burners 113, 115.
The flame 1 is placed at a location where it can receive radiant heat from the contact portion of 19 and utilizes the temperature value (° C) -CO concentration value (ppm) characteristic of the thermocouple 111 as shown in FIG.
The contact between 17, 119 is detected. That is, when the CO concentration value increases, the flame 117, 119
When the width of the flame spreads and the flames come into contact with each other, the amount of radiant heat from the contact portion between the flames 117 and 119 increases and the temperature rises.

According to this embodiment, in order for the thermocouple 111 to detect the synergistic state of the change in the states of the plurality of flames 117, 119, the thermocouple 111 may be installed at a location separated from the flames 117, 119. It is possible to improve the detection accuracy of the contact between the flames 117 and 119.

It should be noted that the above contents are only related to the respective embodiments of the present invention and modifications thereof, and it is needless to say that the present invention is not limited to the above contents.

[0058]

As described above, according to the present invention,
To provide a combustion device capable of improving the detection accuracy of a flame current value in a combustion device that determines normality / abnormality of combustion states of a plurality of burners arranged in parallel by detecting flame currents of some burners. You can

[Brief description of drawings]

FIG. 1 is a block diagram of a combustion device according to an embodiment.

FIG. 2 is a characteristic diagram showing a relationship between an FR current value and a CO concentration value.

FIG. 3 is a flowchart showing a control operation of the configuration of FIG.

FIG. 4 is a flowchart according to a first modified example of the embodiment.

FIG. 5 is a flowchart according to a second modification of the embodiment.

FIG. 6 is a characteristic diagram showing a relationship between an FR current value and an air volume value supplied to the burner.

FIG. 7 is a flowchart according to a third modification of the embodiment.

FIG. 8 is a block diagram of a main part of a combustion device according to another embodiment.

9 is a flowchart showing the control operation of the configuration of FIG.

FIG. 10 is a block diagram of a main part of a combustion device according to a third embodiment.

11 is a diagram showing resistance value-CO concentration value characteristics of the CdS resistance of FIG.

FIG. 12 is a block diagram of a main part of a combustion device according to a fourth embodiment.

FIG. 13 is a diagram showing temperature value-CO concentration value characteristics.

[Explanation of symbols]

1 Outside air suction fan 3 Air inlet 5 metal body 7, 9, 11, 13, 15 burners 19 frame rod 21 flame 27 comparator 29 Gas control device Installation interval between 33 burners 41 Secondary air inlet 71 Basic burner group 73 Extended burner group 79 1st on-off valve 81 Second on-off valve 101 CdS resistance 111 thermocouple

Front page continuation (72) Inventor Hiroshi Somura 43-1 Uozakihama-cho, Higashinada-ku, Kobe-shi, Hyogo Within Japan Yupro Co., Ltd. (72) Inventor Yasuaki Baba 43-1 Uozakihama-cho, Higashinada-ku, Kobe-shi, Hyogo Japan Yupro Incorporated (56) Reference JP 50-95821 (JP, A) JP 58-52913 (JP, A) JP 62-26417 (JP, A) JP 63-238328 (JP, A) A) Actual development Sho 56-154646 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F23N 5/12 F23N 5/24 106

Claims (8)

(57) [Claims] 1. A combustion apparatus having a plurality of burners arranged in parallel, flame current detection means for detecting a flame current by being inserted into a flame of a part of the burners in each of the burners, and based on the flame current detection. And a determination means for determining whether the combustion is abnormal, the installation intervals of the respective burners, at least flames of different burners do not contact each other during normal combustion, and flames of the different burners during abnormal combustion Is set to a distance at which the contact may occur, and the determination means determines that the combustion is abnormal combustion when the flame current exceeds a predetermined threshold value. 2. The combustion device according to claim 1, wherein when the determination means determines abnormal combustion, the combustion of each burner is stopped. 3. The combustion apparatus according to claim 1, wherein the determination means determines that the abnormal combustion can be eliminated when the flame current decreases when the air volume to each of the burners is increased when it is determined that the abnormal combustion has occurred. And continues to control the increase in air flow until the flame current value falls below the threshold value, and if the flame current value does not decrease even with the increase in air flow, it is determined that abnormal combustion cannot be resolved and the combustion stop control of each burner is performed. Combustion device. 4. The combustion apparatus according to claim 1, wherein each of the burners has a first burner group that is always used during combustion, and a second burner group that is used in addition to the first burner group as needed. The flame current detection means is arranged on the side of the first burner group, and the determination means has a relatively small flame current value when only the first burner group is used. Combustion determined to be abnormal combustion when the temperature falls below a threshold value, and abnormal combustion state determined when the flame current value exceeds the threshold value of the second type larger than the threshold value of the first type when both burner groups are used. apparatus. 5. In a combustion device having a plurality of burners arranged in parallel, a state quantity detecting means for detecting a state quantity changing according to a degree of contact between flames of each burner, and a state quantity detecting means for detecting the state quantity of the flame. And a determination means for determining whether the combustion is abnormal based on the installation interval of the burners, flames of different burners do not contact each other at least during normal combustion, and flames of the different burner during abnormal combustion A combustion device that is set to a distance at which mutual contact can occur, and the determination unit determines abnormal combustion when the state quantity of the flame exceeds a predetermined threshold value. 6. The combustion device according to claim 5, wherein the state quantity detection means is a light detection means arranged at a position capable of receiving light from a flame between the burners. 7. The combustion apparatus according to claim 5, wherein the state quantity detection means is a temperature detection means arranged at a location capable of receiving radiant heat from a flame between the burners. 8. The combustion apparatus according to claim 5, wherein the state quantity detection means is a flame current detection means for detecting a flame current by being inserted into a flame of a part of the burners in each of the burners. A combustion device, wherein the means determines whether the combustion state is normal or abnormal based on whether or not the flame current exceeds a predetermined threshold value.