JPH0755135A - Combustion device - Google Patents

Abstract

PURPOSE:To detect uncomplete combustion of a main burner, even when a port of the main burner or a secondary air port of a rectifier is clogged, by a method wherein a sensor burner is made a full primary combustion burner and arranged in the upstream of the rectifier which partitions an air supply passage. CONSTITUTION:A sensor burner 1 is adjacent to a main burner 11 in a burner case 10, and a premixing burner body is formed of a cylindrical body 2 which is opened at the both ends and a burner plate 4 which is mounted in the middle of the crylindrical body 2 and provided with a plurality of burner port. An upper part of the cyrindrical body 2 is a cyrindrical guard 6 which prevents contact by secondary air. The cyrindrical guard 6 is provided with a thermocouple 9, whose heat-receiving part is postioned in a flame. In the burner case 10, a rectifier 20 to rectify supply amount and distribution of the secondary air to the main burner 11 is provided and the sensor burner 1 is arranged in the upstream of the rectifier 20 in an air supply passage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for preventing incomplete combustion of a combustor which compulsorily takes in combustion air and burns it.

[0002]

2. Description of the Related Art Incomplete combustion, which is a cause of carbon monoxide poisoning, is caused mainly by two factors: defective supply / exhaust system of the combustor and indoor oxygen deficiency due to exhaust leakage. Therefore, conventionally, the combustor is provided with a safety device that detects incomplete combustion and stops the combustion. The technology of such a safety device is disclosed in, for example, Japanese Patent Publication No. 59-39647 and Japanese Patent Publication No. 61-3.
1768 and the like.

In the former case, as shown in FIG. 6, an outer cylinder 50 is provided with an inner cylinder 51 to which a mixed gas is supplied, and Bunsen combustion is performed at each opening, and a primary air port 52 and an auxiliary air port 53 are used. Since the Bunsen flame on the inner cylinder 51 side lifts when the oxygen concentration of the inflowing air decreases, the electromotive force of the thermocouple 54 due to this lift phenomenon lowers the gas flow path. In the latter case, the combustion exhaust gas that cannot be exhausted due to a defective exhaust system such as fin blockage is introduced into the air port to reduce the oxygen concentration of the combustion air,
An abnormality is detected by lifting the Bunsen flame. still,
The Bunsen combustion used here is in contrast to the entire primary combustion, and means combustion in which secondary air is taken in from the surroundings to form a flame.

However, even if these safety devices are incorporated into a combustion device for forcibly taking in the combustion air by a fan, incomplete combustion due to oxygen deficiency in the room can be detected, but due to blockage of the air supply / exhaust path and deterioration of fan performance. There was a problem that incomplete combustion due to the decrease in air volume could not be detected. The reason will be described. The flame formation position is
It is determined by the balance between the combustion speed and the gas ejection speed. on the other hand,
The burning rate is determined by the air ratio (the ratio of the actual air amount to the theoretical air amount). Therefore, when the amount of air supplied from the fan decreases, the air ratio of the air-fuel mixture supplied to the safety device also decreases, and the combustion speed decreases. Therefore,
The flame should lift, but in the case of Bunsen combustion, since it is diffusion combustion, not only in the vertical direction but also in the horizontal direction,
Since it spreads in an oblique direction, it does not lift sensitively to a decrease in the air ratio. Moreover, the flow velocity of the secondary air is also reduced, which rather acts to suppress the lift. As a result, even if the thermocouple detects the flame condition,
Incomplete combustion due to the reduction in air volume cannot be prevented.

Therefore, the applicant of the present application has previously proposed a combustion safety device capable of reliably detecting incomplete combustion even when the oxygen deficiency in the room is low or the air flow rate is reduced due to poor supply / exhaust (Japanese Patent Application No. 2003-242242). Flat 5-143058). In this technique, as shown in FIG. 7, the burner plate P is surrounded by a tubular guard G to prevent contact of secondary air in the flame to perform all primary combustion, and the flame formation position at this time is determined by a thermocouple TC. It is something to detect. According to this safety device, the flame formation position is sensitively changed (lifted) to the incomplete combustion regardless of the fluctuation of the combustion air amount and the oxygen deficiency in the room without being affected by the secondary air. It was a very good thing that could be reliably prevented. Therefore, by installing this safety device inside the combustion device such as a water heater, even if the oxygen deficiency in the room is insufficient or the air volume is insufficient due to the blockage of the air supply / exhaust system, the combustion state of the combustion device can be reliably detected and incomplete. Combustion can be prevented.

Here, the state of arrangement of a safety device (hereinafter referred to as a sensor burner) in the combustion device will be described. FIG. 8 shows a schematic configuration of a combustion device including the sensor burner SB. In the combustion device, a plurality of Bunsen combustion-type main burners MB are arranged in a line in a burner case BC at predetermined intervals, and a fan F for supplying combustion air is provided in the bottom of the burner case BC. A sensor burner SB is arranged adjacent to the main burner MB. Further, an adjusting plate CP having a plurality of secondary air ports AH is provided in order to adjust the supply amount and distribution of the secondary air to each main burner MB. The adjusting plate CP is provided so as to partition the air supply passage between the throat MT of each main burner MB and the flame mouth forming surface MH, and also the air supply passage around the sensor burner SB on the lateral extension thereof. , The throat ST and the tip opening GH of the tubular guard G are partitioned by the adjusting plate CP.

[0007]

However, when the sensor burner SB is arranged in the combustion device as described above,
Main burner MB flame outlet and adjusting plate CP secondary air outlet AH
However, there is a problem that the sensor output deviates from the one corresponding to the combustion state of the main burner MB when it is blocked by the combustion products, and it is difficult to detect the incomplete combustion.
The reason will be described below.

A part of the combustion air supplied from the fan F passes through the secondary air port AH of the adjusting plate CP to be used as the combustion secondary air, and a part of the combustion air is supplied to the throat MT of the main burner MB. It passes through and is used as primary air for combustion, and the rest passes through the throat ST of the sensor burner SB and is used as primary air for combustion. Therefore, when the flame opening of the main burner MB or the secondary air opening AH of the adjusting plate CP begins to be blocked, the distribution balance of the combustion air up until now becomes unbalanced, and the sensor burner S
The primary air supplied to B increases. Therefore, the sensor burner SB has a high air ratio and does not lift sensitively to the insufficient air volume of the entire appliance. As a result, the sensor burner S
The output of the thermocouple TC of B does not correspond to the combustion state of the main burner MB. That is, the combustion state of the main burner MB cannot be accurately grasped by the output of the sensor burner SB.

The output of the thermocouple TC and the exhaust CO concentration in such a case will be described. FIG. 9 shows the output of the thermocouple TC and the exhaust CO concentration of the main burner MB with respect to the degree of exhaust gas blockage of the combustion device (due to clogging of the fins of the heat exchanger, etc.). The case where the secondary air port AH of the plate CP is closed is shown, and the case where the solid line is not closed is shown. In this figure, the output of the thermocouple TC is 1 so that the concentration of exhausted CO does not exceed 500 ppm.
It is an example of a case where a system is configured to stop the device when the voltage drops to 0 mV. As shown in the figure, in the case where the secondary air port AH and the like are closed, even if the degree of exhaust blocking of the combustion device is the same, incomplete combustion is likely to occur and the exhaust CO concentration is high. However, the output of the thermocouple TC, on the contrary, takes a high value, which makes it difficult to reduce the exhaust clogging of the instrument. In this example, when the output of the thermocouple TC is lowered to the equipment stop level of 10 mV, exhaust gas blockage has progressed considerably and the exhaust CO concentration has already reached 2000 ppm or more. Therefore, if the secondary air port AH or the like is closed, the incomplete combustion of the device cannot be reliably detected. An object of the combustion apparatus of the present invention is to solve the above problems and to reliably detect incomplete combustion of a device even when the secondary air port of the adjusting plate or the flame port of the main burner is closed.

[0010]

In order to solve the above-mentioned problems, the combustion apparatus of the present invention comprises an air supply passage into which combustion air is sent by a fan, a main burner provided in the air supply passage, and the air. An adjusting plate having a plurality of secondary air ports for dividing the supply passage to adjust the supply amount and distribution of secondary air to the main burner, and a sensor burner for detecting incomplete combustion of the main burner were provided. In the combustor, the sensor burner includes a premix burner body having a burner plate having a plurality of flame openings, a tubular guard surrounding the burner plate to prevent contact of secondary air in the flame, and formation of the flame. A flame detector that outputs a detection signal according to the position is provided, and it is arranged on either one of the upstream side or the downstream side of the adjustment plate in the air supply passage. To.

[0011]

The combustion apparatus of the present invention having the above structure detects the combustion state of the main burner provided in the air supply passage to which the combustion air is supplied by the fan, by the output of the flame detector of the sensor burner. In this sensor burner, the flame formed on the burner plate is prevented from coming into contact with the secondary air by the tubular guard, and the entire primary combustion is performed, and a detection signal corresponding to the flame formation position is output. In a normal state, a flame is formed on the burner plate, but when the amount of combustion air decreases due to a defective supply / exhaust system, the air ratio of the premix burner decreases and the combustion speed decreases. In this case, since the combustion is all primary combustion, the state of the flame changes only in the fuel injection direction, and the flame lifts sensitively. Therefore, the combustion state of the main burner can be grasped sensitively. If the secondary air port of the adjusting plate provided by partitioning the air supply passage is blocked or the flame port of the main burner is blocked, the amount of air supplied to the main burner decreases, but the sensor burner is located upstream of the adjusting plate. Alternatively, since it is arranged on one of the downstream sides, the amount of air supplied to the sensor burner also decreases accordingly. In other words, since there is no partition between the air intake section of the sensor burner and the exhaust section of the combustion exhaust gas, both parts have almost the same pressure, and the secondary air port of the adjustment plate and the flame port of the main burner are blocked. However, the combustion air does not go around the sensor burner, and the distribution of the combustion air is not disturbed. As a result,
The combustion state of the main burner can be represented by the combustion state of the sensor burner.

[0012]

EXAMPLES In order to further clarify the constitution and operation of the present invention described above, preferred examples of the combustion apparatus of the present invention will be described below. FIG. 1 shows a schematic configuration of a combustion apparatus as one embodiment, and FIG. 2 shows a schematic configuration of a sensor burner used in the combustion apparatus.

First, the sensor burner will be described. The sensor burner 1 is provided adjacent to the main burner 11 in a burner case 10 of a forced combustion type gas water heater, which will be described later. The sensor burner 1 has a cylindrical body 2 with both ends open, and a plurality of sensor burners mounted in the middle of the cylindrical body 2. The premixed burner main body 5 is constituted by the burner plate 4 (in this embodiment, a ceramic plate is used) in which the flame port 3 is formed, and the upper part (above the burner plate 4) of the cylinder 2 is filled with secondary air. It is a cylindrical guard 6 that prevents contact. More specifically, the lower opening 7 of the cylindrical body 2 is used as an inlet for the primary air for combustion, and the fuel gas nozzle 19 is inserted from the lateral wall of the inlet to eject the fuel gas upward in the cylindrical body 2. Therefore, the cylindrical body 2 has a mixing chamber 8 below the burner plate 4, and the opening of the lower opening 7 is set so that the air ratio in the mixing chamber 8 is 0.9 when the air ratio is normal. . This mixing ratio (0.9) is set so that the combustion speed becomes maximum. That is, when the mixing ratio deviates from this value, the combustion speed becomes slow.

The air-fuel mixture mixed in the mixing chamber 8 is ejected from each flame port 3 of the burner plate 4 and is transferred from the main burner 11 of the water heater described later to form a flame on the plate surface. In this case, the supply of the secondary air is blocked by the tubular guard 6 surrounding the flame, and the entire primary combustion is performed.
A thermocouple 9 is attached to the tubular guard 6 from the lateral direction, and its heat receiving portion 9a is positioned inside the flame. The thermocouple 9 is connected to a combustion controller (not shown) of the water heater, and is configured to open and close an electromagnetic valve (not shown) provided in the gas flow path to the main burner 11 according to the electromotive force thereof. ing. That is, when the electromotive force of the thermocouple 9 becomes equal to or lower than a predetermined level, the gas flow passage is closed. The electromagnetism of the thermocouple 9 may adsorb and hold the magnet safety valve to keep the gas flow path open.

The sensor burner 1 thus constructed is
As shown in FIG. 1, it is attached to the burner case 10 of the water heater. In the burner case 10, press-molded flat Bunsen combustion type main burners 11 are arranged in parallel at predetermined intervals, and a gas nozzle (not shown) is arranged in the opening of the throat 12 to supply fuel gas. A fan 15 forcibly supplying combustion air is provided at the bottom of the burner case 10. A combustion chamber (not shown) is provided in the upper opening of the burner case 10, a heat exchanger (not shown) is provided in the upper part of the combustion chamber, and an exhaust part is provided in the upper part of the heat exchanger (not shown). To be In the figure, reference numeral 13 indicates a flame port forming surface of the main burner 11, and reference numeral 14 indicates a sleeve fire cap for enhancing the flame holding effect. The sensor burner 1 is arranged at the end of a plurality of such main burners 11 arranged side by side.

Inside the burner case 10, the main burner 1
An adjusting plate 20 for adjusting the supply amount and distribution of the secondary air to the No. 1 (the primary air amount is also adjusted accordingly) is provided.
The adjusting plate 20 is a plate having a plurality of secondary air ports 21 formed therein, and is provided with the throat 12 of the main burner 11 and the flame port forming surface 1.
It is provided so as to partition the secondary air supply path between the second and third parts.
The adjusting plate 20 is provided in a planar shape between the main burners 11, but is bent upward between the sensor burner 1 and the main burner 11 to form a step portion 22 so as to cover above the sensor burner 1. is doing. That is, the sensor burner 1 is arranged in the air supply passage on the upstream side of the adjusting plate 20.
An exhaust port 23 is formed in the step portion 22 of the adjusting plate 20 at a position facing the opening of the tubular guard 6 of the sensor burner 1.

Next, the operation of the sensor burner 1 will be described. When the combustion air is normally sent into the burner case 10, a predetermined primary air is also supplied to the sensor burner 1 and a stable flame is formed on the burner plate 4.
A predetermined electromotive force is output from the thermocouple 9. When the air volume of the combustion air decreases due to the fin clogging of a heat exchanger (not shown) or a defective supply / exhaust system, the main burner 11 starts incomplete combustion. At this time, the air ratio in the mixing chamber 8 of the sensor burner 1 decreases, the combustion speed decreases, the flame formed on the burner plate 4 lifts, and as shown in FIG. A flame is formed at the tip opening. In other words, during the entire primary combustion, the flame lifts sensitively to the reduction of the air volume (the reduction of the air ratio), and when it reaches the tip opening of the tubular guard 6, the secondary air is supplied from around it and the Bunsen combustion is performed. Is done. Also, during Bunsen combustion,
Since it is diffusion combustion and the force for lifting the flame upward due to the decrease in the air volume is reduced, it hardly lifts with respect to the change in the air volume.

Therefore, the output of the thermocouple 9 sharply decreases with the progress of exhaust blocking, as shown by the solid line in FIG. Utilizing this fact, the exhaust CO concentration is 500 in this embodiment.
It is set to stop the device (close the gas flow path) at the point where the output of the thermocouple 9 is 10 mV, which is ppm. Therefore, before the CO concentration becomes high due to insufficient air flow, the thermocouple 9
Is less than or equal to the set value, and incomplete combustion of the main burner 11 can be prevented.

By the way, the flame port of the main burner 11 and the secondary air port 21 of the adjusting plate 20 may be blocked by the combustion products. In such a case, since the sensor burner 1 is arranged in the upstream air supply passage of the adjusting plate 20, the air supply amount to the sensor burner 1 is also reduced like the main burner 11. That is, even if the pressure on the upstream side increases due to the blockage of the secondary air port 21 and the like, the lower opening 7 of the sensor burner 1 and the front end opening of the cylindrical guard 6 are not partitioned by the adjusting plate 20 and are therefore almost not separated. The same pressure is provided, and combustion air is prevented from flowing into the mixing chamber 8 of the sensor burner 1.

As a result, the output of the thermocouple 9 takes a lower value as compared with the case where the secondary air port 21 and the like are not closed (shown by the solid line), as shown by the broken line in FIG. If the exhaust blockage of the device (blocking of heat exchange fins etc.) progresses, it will decrease early. On the other hand, as for the discharged CO concentration, the air ratio of the main burner 11 becomes low when the secondary air port 21 and the like are closed, and as shown by the broken line in FIG. The amount increases. As a result, when the output of the thermocouple 9, which is the standard for determining incomplete combustion, is 10 mV, the exhaust CO concentration is approximately 500 p.
pm, the incomplete combustion can be reliably detected at a desired level without being substantially affected by the blockage of the secondary air port 21 and the like.

The above explanation is for the case where the air volume is insufficient. However, when the oxygen concentration in the room is reduced, the amount of oxygen contributing to combustion is reduced even if the air volume (air ratio) is the same.
The combustion speed becomes slow, and the flame of the sensor burner 1 lifts sensitively as described above. As a result, the electromotive force of the thermocouple 9 is sufficiently reduced before the concentration of exhausted CO rises, and the gas flow path can be reliably closed at a safe level. In the case of oxygen deficiency, after the flame is held at the tip of the tubular guard 6, the misfire occurs early.

Next, another embodiment of the combustion device will be described. The combustion apparatus shown in FIG. 5 is obtained by changing the arrangement of the sensor burner 1 shown in the previous embodiment. That is, the main burner 11 is provided with the adjusting plate 30 having a plurality of secondary air ports 31 formed therein.
And a sensor burner 1 are bent downward, and a step portion 32 is formed below the sensor burner 1 so as to partition the air supply passage. Therefore, the sensor burner 1 is arranged in the air supply passage downstream of the adjusting plate 30. Also in this embodiment, when the secondary air port 31 and the like are closed, the lower opening 7 of the sensor burner 1 and the cylindrical guard 6 are provided.
Since it is not partitioned from the tip end opening by the adjusting plate 30, the pressure becomes almost the same, and the combustion air is prevented from flowing into the mixing chamber 8 of the sensor burner 1. As a result, similar to the previous embodiment, the incomplete combustion can be reliably detected at a desired level without being substantially affected by the blockage of the secondary air port 31 and the like of the adjusting plate 30.

In the two embodiments described above, the gas flow passage is closed when the electromotive force of the thermocouple 9 decreases below a predetermined value. The rotation speed may be adjusted. In other words, when the air ratio decreases due to back wind from the exhaust duct (not shown), fin blocking, or the like, there is a case where the device can be used without stopping by increasing the rotation speed of the fan 15. Therefore, when the electromotive force of the thermocouple 9 is reduced to a preset level, the rotational speed of the fan 15 is increased and the electromotive force is not recovered even when the rotational speed reaches a predetermined rotational speed, that is, the air ratio. The gas flow path is closed and the instrument is stopped when the power does not increase. Also, the fan 15
The gas flow path may be closed when the electromotive force does not recover within a predetermined period of time after the number of revolutions is increased.

The fan speed may be controlled so that the electromotive force of the thermocouple 9 is always a constant value. In other words, the electromotive force of the thermocouple 9 is used as the feedback control factor for the fan 15
It controls the rotation speed of. In this case, when the rotation speed of the fan 15 does not fall within the predetermined range, the gas passage is closed to prevent incomplete combustion. The control based on the electromotive force of the thermocouple 9 is possible because the sensor burner 1 detects the air volume shortage and the oxygen deficiency with extremely high accuracy, and the Bunsen combustion lift detection as in the related art provides accurate control. It is impossible even if you want. At the start of combustion, the control operation is not performed until the electromotive force of the thermocouple 9 stabilizes.

The embodiment of the present invention has been described above.
The present invention is not limited to these examples, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention. For example, the invention can be applied not only to a water heater but also to a combustor such as a fan heater. Also,
The sensor burner can be used as a sensor for detecting a decrease in air flow even in an external type device in which there is no fear of oxygen deficiency.

[0026]

As described above in detail, according to the combustion apparatus of the present invention, even if the secondary air port of the adjusting plate or the flame port of the main burner is closed, the distribution of the combustion air is biased to the sensor burner. This can be prevented, the combustion state of the main burner can be represented by the combustion state of the sensor burner, and incomplete combustion can be reliably detected.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a combustion apparatus as an example.

FIG. 2 is a schematic configuration diagram of a sensor burner incorporated in a combustion device.

FIG. 3 is an explanatory diagram showing a flame shape of the sensor burner when the air volume is insufficient.

[Fig. 4] Output of thermocouple and CO emission with respect to exhaust blocking degree
It is a graph showing the relationship with the concentration.

FIG. 5 is a schematic configuration diagram of a combustion apparatus as another embodiment.

FIG. 6 is a schematic configuration diagram of a conventional combustion safety device.

FIG. 7 is a schematic configuration diagram of a previously proposed combustion safety device.

FIG. 8 is a schematic configuration diagram of a combustion device incorporating a combustion safety device of the prior application.

FIG. 9 is a graph showing the relationship between the output of a thermocouple and the exhaust CO concentration with respect to the degree of exhaust blockage in the combustion device of the prior application.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sensor burner, 2 ... Cylindrical body, 3 ... Flame mouth, 4 ... Burner plate, 5 ... Premixing burner main body, 6 ... Cylindrical guard, 7 ... Lower opening, 8 ... Mixing chamber, 9 ... Thermocouple, 1
0 ... Burner case, 11 ... Main burner, 12 ... Throat, 13 ... Flame mouth forming surface, 15 ... Fan, 20, 3
0 ... Adjusting plate, 21, 31 ... Secondary air port, 22, 32
… Steps.

Claims (1)

[Claims] 1. An air supply passage into which combustion air is sent by a fan, a main burner provided in the air supply passage, and a supply amount and distribution of secondary air to the main burner by partitioning the air supply passage. In a combustor including an adjusting plate having a plurality of secondary air ports for adjusting the above and a sensor burner for detecting incomplete combustion of the main burner, the sensor burner is a burner plate having a plurality of flame ports. A premixed burner main body having, a tubular guard that surrounds the burner plate to prevent contact of secondary air of flame, and a flame detector that outputs a detection signal according to the flame formation position, and A combustion apparatus, characterized in that it is arranged on either one of the upstream side and the downstream side of the adjusting plate in the air supply passage.