JPH11148615A - Low-nox combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the generation of unburnt hydrocarbon upon igniting and fire distinguishing by a method wherein fuel is burnt by only concentrated flame temporarily upon igniting, in a low-NOx combustion device. SOLUTION: Fuel, supplied from a fuel supplying system 19, is passed through an intercepting valve 11 and the flow rate thereof is regulated by a proportional valve 17 so as to have a predetermined value, then, the flow of the fuel is branched into a concentrated fuel supplying system 12 and a thin fuel supplying system 13 to inject from a concentrated fuel nozzle 14 and a thin fuel nozzle 15 into a concentrated fuel burner 10 and a thin fuel burner 11. The flow of air, supplied from a fan 21, is regulated by a flow regulating unit 22 at the bottom part of a burner case 20 so as to be uniform flow and, thereafter, the air is supplied from an air supplying port into the burners. The air is mixed into the fuel, supplied from the concentrated fuel nozzle 14, in the concentrated fuel burner and the mixture flows out through a flame port as concentrated mixture, concentrated much more than a logical mixing ratio, and the mixture is ignited by an igniter 23 to form stabilized concentrated flame. According to this method, the discharging concentration of unburnt hydrocarbon upon igniting can be reduced remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-NOx combustion apparatus of a lean-burn type mainly using gas or petroleum fuel, and particularly to unburned hydrocarbons (hereinafter referred to as HC and HC) which are generated for a short time during ignition and extinguishing. ).

[0002]

2. Description of the Related Art A conventional low NOx combustion apparatus of this type is disclosed in Japanese Patent Application Laid-Open No. 5-118510. In this low NOx combustion apparatus, a supply pipe 1 for supplying a fuel gas is branched into a first path 2 and a second path 3 as shown in FIG.
At the tip, a nozzle 6 directed to the dark burner 5 is provided. The second passage 3 is provided with a gas amount adjusting means 7, and a tip thereof is provided with a secondary fuel gas supply pipe 9 having a jet port 8 opened to a space.

The flow rate of the fuel supplied from the supply pipe 1 to the first path 2 is adjusted by the second governor 4,
And is supplied into the rich burner 5 together with a part of the air supplied from a fan (not shown) to become a rich primary air-fuel mixture and is blown out from the rich flame port into the combustion space. On the other hand, the fuel supplied to the second passage 3 flows out from the ejection port 8 of the secondary fuel gas supply pipe 9 and mixes with a large amount of air in the space inside the burner to become a lean secondary air-fuel mixture. It is blown out from a flame outlet (not shown) into the combustion space. Therefore, rich flame and light flame are produced in the combustion space, and the mixture becomes rich and lean combustion, thereby realizing low NOx combustion. Here, when the combustion amount is less than the predetermined combustion amount, the gas amount adjusting means 7 of the second path 3
Closed the path and supplied air instead of the lean air-fuel mixture from the light flame outlet to perform Bunsen combustion.

[0004]

SUMMARY OF THE INVENTION The conventional low NO
In the x-burning device, rich flame is formed by the fuel of the first passage 2 and light flame is formed by the fuel of the second passage 3, thereby realizing the lean-burn combustion.
Second governor 4 and gas amount adjusting means 7 provided in each path
Is for adjusting each flow rate in accordance with the entire combustion amount, and is not for adjusting the supply of fuel for light flame at the time of ignition or fire extinguishing. I could not do it. In addition, there is no means for controlling the amount of air for rich flame or light flame, and fuel is supplied in a state where a large amount of air flow is present in the burner during ignition at the time of ignition. There is a problem that the outside lean air-fuel mixture is jetted out as it is, and a problem that fuel remaining in the second passage 3 flows out after the supply pipe 1 is closed even at the time of fire extinguishing, and is jetted as it is as HC. Was. Further NO
In order to reduce x, the fuel division ratio is supplied to the first path 2 and is reduced and supplied to the second path 3 so that the flame temperature is low and the NOx is low.
It is necessary to increase the amount of combustion of the light flame
There is a problem that the amount of generation of odor increases.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a combustion apparatus that suppresses the generation of HC during ignition and extinguishing.

[0006]

In order to solve the above-mentioned problems, the present invention combusts fuel by combining a rich flame generated by burning a rich mixture with a lean flame generated by burning a lean mixture. This is a low NOx combustion device, in which fuel is temporarily burned only by rich flame at the time of ignition.

A low NOx combustion apparatus which burns fuel by combining a rich flame generated by combustion of a rich air-fuel mixture and a lean flame generated by combustion of a lean air-fuel mixture. The fuel is burned in the fuel cell.

[0008] According to the above invention, at the time of ignition, the fuel is temporarily burned with only the rich flame, so that the rich flame can be formed and then the lean flame can be formed.
Emissions can be reduced.

Further, at the time of extinguishing the fire, the lean flame is extinguished in advance, so that the fuel can be temporarily burned only with the rich flame, so that the lean mixture can be burned with the remaining rich flame to reduce HC. .

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention can be embodied in the form described in each claim.
The x-burning device includes a rich burner that is supplied with a rich mixture to form a rich flame, a light burner that is supplied with a thin mixture and forms a light flame, and a rich fuel that supplies fuel to the rich burner. Supply system,
It has a lean fuel supply system for supplying fuel to the lean burner, a lean fuel control means provided in the lean fuel supply system, and a control unit for controlling the lean fuel control means.

At the time of ignition, the control unit controls the lean fuel control means to supply fuel from the lean fuel supply system with a predetermined time delay from the rich fuel supply system, so that a stable rich flame is formed on the rich burner. After that, a lean air-fuel mixture is ejected from the light burner, and the mixture is heated by the rich flame and can be completely burned from the initial stage of the ejection, so that the amount of HC emission can be greatly reduced.

According to a second aspect of the present invention, there is provided a low NOx combustion apparatus comprising: a rich burner supplied with a rich air-fuel mixture to form a rich flame; and a lean burner supplied with a thin air-fuel mixture to form a light flame. Rich fuel supply system for supplying fuel to the rich burner and light burner
A fuel supply system for supplying fuel to the fuel tank; a light fuel control means provided in the light fuel supply system; and a control unit for controlling the light fuel control means.

When the fire is extinguished, the control unit controls the lean fuel control means to cut off the fuel in the lean fuel supply system ahead of the rich fuel supply system. The flame is extinguished, and the lean mixture remaining in the light burner before the extinguishing is heated by the rich flame and can be completely burned, so that the amount of HC emission can be greatly reduced.

According to a third aspect of the present invention, there is provided a low NOx combustion apparatus comprising: a rich burner supplied with a rich air-fuel mixture to form a rich flame; and a lean burner supplied with a thin air-fuel mixture to form a lean flame. Rich fuel supply system for supplying fuel to the rich burner and light burner
A fresh fuel supply system for supplying fuel to the burner, a fresh air supply system for supplying air to the burner, a fresh air control means provided in the fresh air supply system, and a controller for controlling the fresh air control means. Having.

At the time of ignition, the control unit controls the lean air control means to reduce the amount of supplied air for a predetermined time, during which the fuel supplied from the lean fuel supply system is transiently rich in the lean burner. The fuel mixture becomes low and the fuel concentration is reduced to form an original light flame after the fuel is ignited and a stable flame is formed at an early stage, and a stable flame is formed at an early stage, so that the emission amount of HC can be reduced. .

According to a fourth aspect of the present invention, there is provided a low NOx combustion apparatus comprising: a rich burner supplied with a rich air-fuel mixture to form a rich flame; and a lean burner supplied with a thin air-fuel mixture to form a light flame. Rich fuel supply system for supplying fuel to the rich burner and light burner
A fresh fuel supply system for supplying fuel to the burner, a fresh air supply system for supplying air to the burner, a fresh air control means provided in the fresh air supply system, and a controller for controlling the fresh air control means. Having.

When the fire is extinguished, the control unit controls the lean air control means to reduce the amount of supplied air prior to the stop of the lean fuel supply system. In this case, the mixture becomes transiently rich, a stable flame is formed, and the fire is extinguished after the majority of the mixture is consumed. Since the combustion can be completed until immediately before the fire is extinguished, the amount of HC emission can be reduced.

[0018]

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

(Embodiment 1) FIG. 1 shows a configuration diagram of a low NOx combustion apparatus according to Embodiment 1 of the present invention. FIG. 2 is a timing chart, and FIGS. 3 and 4 show a mixture concentration characteristic diagram and an HC emission characteristic diagram at the time of ignition of the apparatus, and the explanation will be given based on these.

In FIG. 1, a plurality of light burners 11 having flame ports are alternately provided adjacent to each other, like the dark burner 10 having many flame ports (not shown). Each dark bar
The rich nozzles 14 and the light nozzles 15 provided at the ends of the rich fuel supply system 12 and the light fuel supply system 13 are provided to face the burner 10 and each light burner 11, respectively. On the upstream side of the lean fuel supply system 13, a lean fuel control means 16 is provided.
Is connected to the fuel supply system 19 provided with the. Dark bar
A burner case 20 for accommodating the burner 10 and the light burner 11 is provided with a fan 21 and a rectifying section 22 at the bottom and an igniter 23 at the top. Further, the lean fuel control means 16,
A control unit 25 is provided which is connected to the proportional valve 17, the shut-off valve 18, the fan 21, and the igniter 23 by a control line 24 and controls them.

Next, the operation and operation will be described. The fuel supplied from the fuel supply system 19 passes through the shut-off valve 18,
After being adjusted to a predetermined flow rate by the proportional valve 17, the concentrated fuel supply system 1
2 and a light fuel supply system 13, respectively, and are ejected into the dark burner 10 and the light burner 11 from the dark nozzle 14 and the light nozzle 15 at the tip. On the other hand, the air supplied from the fan 21 is rectified into a uniform flow at the bottom of the burner case 20 by the rectifier 22 and supplied to each burner from the air supply port. In each burner, the fuel is mixed with the fuel supplied from the rich nozzle 14 to form a rich mixture that is richer than the stoichiometric mixture ratio, flows out of the flame opening, and is ignited by the igniter 23 to form a stable rich flame. In each light burner 11, the fuel is mixed with the fuel supplied from the light nozzle 15 to form a lean mixture, which flows out of the flame opening, and is stabilized by the thermal and chemical influences of the rich flames on both sides. A light flame is formed. In order to reduce the NOx, the rich nozzle 14 and the light nozzle 15 are set so that the flame temperature is low and unstable, but the burning amount of the lean flame with little NOx increases.
Is adjusted.

The operation and characteristics at the time of ignition will be described with reference to FIGS. 2 to 4. As shown in FIG. 2, when an ignition signal enters the control unit 25, the fan 21 and subsequently the igniter 23 operate. After that, the shutoff valve 18 is opened, and the fuel is adjusted to a small flow rate by the proportional valve 17 and supplied to the rich burner 10. Then, as shown in FIG. 3, the mixture concentration in the rich burner 10 rapidly increases as shown by a curve A, and ignites at time T1 when the concentration exceeds the lean side flammable limit concentration L2 to form a stable rich flame. Is done. Next, when a predetermined delay time TA has elapsed, an operation signal of the lean fuel control means 16 is sent from the control unit 25, and fuel is injected from the lean fuel supply system 13 to the lean burner 11. The lean mixture concentration in the light burner 11 ignites at the time T3 as shown by the curve B1, but the lean mixture that has been ejected from the time TA to the time T3 and that is outside the combustible range is formed earlier. Since the combustion is performed by the rich flame, the emission of HC is greatly reduced. Therefore, HC is discharged only in the region Q until the rich flame is formed. On the other hand, the concentration of the lean gas mixture in the conventional lean burner is as shown by a curve B, and the portion of the region P until a rich flame is formed becomes HC and is discharged. Here, as described above, in order to reduce NOx, the fuel is generally supplied to the light fuel supply system 13 three to five times as much as the rich fuel supply system 12, so that the amount of HC is increased accordingly. Therefore, as shown in FIG. 4, the HC emission concentration at the time of ignition is in the range P
However, in the present invention, only the region Q is obtained as shown by the curve B, which can be greatly reduced.

(Embodiment 2) FIG. 1 shows a low NOx combustion apparatus according to Embodiment 2 of the present invention.

The second embodiment differs from the first embodiment in the control method at the time of fire extinguishing.

The components having the same reference numerals as in the first embodiment have the same structure, and the description will be omitted. Next, the fire extinguishing operation and operation will be described with reference to FIGS. 5 to 7. As shown in FIG. 5, when the fire extinguishing signal enters the control unit 25, the lean fuel control means 16 operates and the lean fuel supply system 13 Is closed and the light flame on the light burner 11 is extinguished. Then, after a short time TC elapses, the shut-off valve 18 is operated, the fuel supply system 19 is closed, the fuel supply to the rich fuel supply system 12 is stopped, and the rich flame on the rich burner 10 is extinguished. After the passage, the post-purge is completed and the fan 21 stops.

As shown in FIG. 6, when the fire extinguishing signal is issued at time T4 and the lean fuel control means 16 is operated, the lean burner 11 is activated.
As shown by the curve Y1, the concentration of the air-fuel mixture rapidly decreases, and extinguishes at time T5 when the concentration falls below the lean side flammable limit concentration L2, and becomes zero at time T6. Also short time TC
Is elapsed, the fuel supply to the rich fuel supply system 12 is stopped,
The concentration of the rich mixture in the rich burner 10 extinguishes at time T7 as shown by the curve X. Then, the lean air-fuel mixture out of the flammable range ejected from the time point T5 to the time point T6 is burned by the rich flame formed up to the time point T7, so that the emission of HC is greatly reduced. Therefore, the emission of HC is controlled by the rich burner 10.
It is a portion of only the region QQ until the fuel concentration in the inside becomes zero. On the other hand, the light mixture concentration in the conventional light burner is represented by a curve Y.
The portion of the region PP until the rich flame is extinguished and the fuel concentration becomes zero becomes HC and is discharged. As described above, in order to reduce NOx, the lean fuel supply system 1
Since 3 is usually supplied with 3 to 5 times as much fuel as the rich fuel supply system 12, the amount of HC generated increases accordingly. Accordingly, as shown in FIG. 7, the HC emission concentration at the time of fire extinguishing is the sum of the area PP and the area QQ as in the conventional curve d, but in the present invention, it becomes only the area QQ as in the curve e and can be greatly reduced.

The combustion is extended by the time the fire extinguishing signal is generated and the shut-off valve 18 is closed. However, since the time TC is usually as short as several seconds, the effect on the combustion device is small.
For example, even in the case of a water heater requiring a high-speed response, the so-called post-boiler temperature slightly increases, and there is no practical problem if a slight adjustment is made.

(Embodiment 3) FIG. 8 shows a low NOx combustion apparatus according to Embodiment 3 of the present invention. In the third embodiment, the first embodiment
The difference from (or 2) is that the lean fuel control means 16 is eliminated and a lean air control means 31 is provided instead.

The components having the same reference numerals as in the first embodiment have the same structure, and the description is omitted. In FIG. 8, a concentrated air supply system 26 connected to the concentrated burner 10 is located downstream of the rectifying section 22.
And a fresh air supply system 27 connected to the fresh burner 11. A damper 28 is connected to the fresh air supply system 27 with the connecting portion 2.
At 9 a fresh air control means 31 joined to the drive 30 is provided.

Next, the operation and operation will be described. The fuel supplied from the fuel supply system 19 passes through the shut-off valve 18 and is adjusted to a predetermined flow rate by the proportional valve 17, and then the rich fuel supply system 12 and the light fuel supply Each of the dark nozzles 1 at the tip divided into systems 13
4 and the light nozzles 15 are ejected into the dark burner 10 and the light burner 11, respectively. On the other hand, the air supplied from the fan 21 is rectified into a uniform flow at the bottom of the burner case 20 by the rectifying section 22, and then passes through the rich air supply system 26 to supply the fresh air to the rich burner 10. System 27 and damper 28
And supplied to the light burner 11. Each burner 10
Inside, the fuel supplied from the rich nozzle 14 and the air supplied from the rich air supply system 26 are mixed to form a rich mixture that is richer than the stoichiometric mixture ratio, flows out, and is ignited by the igniter 23 to form a stable rich flame. I do. In each of the burners 11, the fuel supplied from the light nozzle 15 and the air supplied from the light air supply system 27 are mixed and flow out as a thin lean mixture. A stabilized light flame is formed under the influence of chemicals. In order to reduce NOx, the opening area ratio between the rich nozzle 14 and the light nozzle 15 is adjusted so that the flame temperature is low and unstable, but the burning amount of the lean flame with little NOx increases.

The operation and characteristics at the time of ignition will be described with reference to FIGS. 9 to 11. As shown in FIG. 9, when an ignition signal enters the control unit 25, the fan 21 and subsequently the igniter 23 operate. After that, the shutoff valve 18 is opened, and the fuel is adjusted to a small flow rate by the proportional valve 17 and supplied to the rich burner 10. Then, as shown in FIG. 10, the concentration of the mixture in the rich burner 10 increases as shown by the curve A and ignites at the time T1 when the concentration exceeds the lean side flammable limit concentration L2, and a stable rich flame is formed. . On the other hand, in the fresh air supply system 27, in the initial state, the damper 28 is closed and the passage is narrow, so that only a small amount of air is supplied to the fresh burner 11.
Therefore, the concentration of the air-fuel mixture in the light burner 11 rapidly increases as shown by a curve B2, and the lean side flammable limit concentration L2
At time T0 after the ignition, the ignition is performed. At this time, the concentration of the air-fuel mixture is higher than in the steady state, so that a stable flame is formed without the influence of the rich flame. Next, when a predetermined time TB elapses, an operation signal of the fresh air control means 31 is sent from the control unit 25, the drive unit 30 is operated, and the light burners 11 are connected by the connecting unit 29.
Is opened, and a large amount of air is supplied from the fresh air supply system 27 to each of the burners 11, so that the concentration of the air-fuel mixture rapidly decreases and becomes a steady flame. Here, the lean air-fuel mixture out of the flammable range that has been ejected before the light burner 11 ignites after the shut-off valve 18 is opened is the sum of the area R and the area Q0 of the rich burner 10 until the time T0. . On the other hand, the concentration of the lean air-fuel mixture in the conventional lean burner is as shown by a curve B. The sum of the region P up to the point T1 at which the rich flame ignites and the region Q of the rich burner 10 becomes HC and is discharged. You. Here, as described above, in order to reduce NOx, since the fuel is usually supplied to the light fuel supply system 13 three to five times as much as the rich fuel supply system 12, the generation of HC increases accordingly. Also, T0 <T
By adjusting the damper 28 in the initial stage so as to be 1, the region R and the region Q0 can be reduced. Therefore, as shown in FIG. 11, the HC emission concentration at the time of ignition is:
In the present invention, as compared with the conventional curve A, the curve C is obtained, which can be greatly reduced.

As shown in FIG. 10, in this system, the fuel supply from the lean fuel supply system 13 having a large combustion amount is faster than that in FIG. 3 of the first embodiment, so that the heating rate can be increased at the same time.

(Embodiment 4) FIG. 8 shows a low NOx combustion apparatus according to Embodiment 4 of the present invention.

The fourth embodiment differs from the third embodiment in the control method at the time of fire extinguishing.

The components having the same reference numerals as those of the third embodiment have the same structure, and the description is omitted. Next, the fire extinguishing operation and function will be described with reference to FIGS. 12 to 14. As shown in FIG.
As a result, the driving unit 30 is operated, and the dampers 28 corresponding to the respective light burners 11 are closed by the connecting unit 29, and the concentration of the air-fuel mixture in the light burners 11 increases, and the flame once becomes stable. Then, after a short time TD elapses, the shut-off valve 18 is actuated and the fuel supply is stopped, and the rich flame on the rich burner 10 and the light burner 11
The upper stable flame is extinguished, and after a lapse of a predetermined time, the post-purge is completed and the fan 21 stops.

As shown in FIG. 13, when the fire extinguishing signal is issued at time T4 and the fresh air control means 31 is activated,
The damper 28 closes and the air supply amount of the fresh air supply system 27 decreases. After a lapse of time TD, the shutoff valve 18 is closed to stop the fuel supply. When the fuel remaining in the lean fuel supply system 13 enters the lean burner 11 after the shut-off valve 18 is closed, the amount of air decreases because the amount of air decreases.
As shown in the curve Y2, the flame once rises rapidly, and the unstable light flame changes to a stable flame. However, since no fuel is supplied, the concentration of the air-fuel mixture decreases and falls below the lean side flammable limit concentration L2. At time T6, the fire extinguishes, and at time T8, the concentration becomes zero. Similarly, when the shut-off valve 18 is operated and the fuel supply to the thickener supply system 12 is stopped, the mixture concentration in the rich burner 10 is represented by a curve X.
As shown in the figure, the fire extinguishes at time T7 when the temperature falls below the lean side flammable limit concentration L2, and then the concentration becomes zero. That is, the fuel remaining in the lean fuel supply system 13 burns by itself on the lean burner 11 with a stable flame until time T6, and thereafter, the lean mixture which has been ejected from time T6 to time T7 outside the combustible range is
It burns with the rich flame formed until time T7.
Therefore, only the region RR from time T7 to time T8 is discharged from the light burner 11 as HC. On the other hand, the concentration of the lean mixture in the conventional lean burner is as shown by a curve Y, and the rich flame extinguishes at time T7, and the portion of the region PP until the fuel concentration becomes zero becomes HC and is discharged. As described above, in order to reduce NOx, the lean fuel supply system 1
Since 3 is usually supplied with 3 to 5 times as much fuel as the rich fuel supply system 12, the amount of HC generated increases accordingly. Therefore, as shown in FIG. 14, the HC emission concentration at the time of fire extinguishing was the sum of the region PP and the region QQ as in the conventional curve d, but in the present invention, the region RR and the region QQ are smaller than the region PP as in the curve.
And can be reduced.

In each of the above embodiments, the burner unit has a configuration in which a plurality of dark burners and a plurality of light burners are alternately arranged. However, it is not always necessary to alternately arrange the burners. A larger burner and a smaller burner can be installed as a so-called pilot burner near the light burner.

In each of the above embodiments, the configuration of the drive unit and the damper has been described as the fresh air control means. However, the present invention is not limited to such a form, and any means capable of adjusting the air flow rate may be used.

[0039]

As described above, the low NOx combustion apparatus according to the first aspect of the present invention temporarily burns fuel only with a rich flame at the time of ignition, so that HC from the lean burner is burned.
There is an effect that emission can be reduced.

The low NOx combustion apparatus according to the second aspect of the present invention has the effect of reducing the emission of HC from the light burner by temporarily burning the fuel only with the rich flame when extinguishing the fire.

Further, in the low NOx combustion apparatus according to the third aspect, since the formation of the rich flame and the formation of the lean flame are delayed at the time of ignition, the HC emission from the lean burner can be reduced. There is.

Further, the low NOx combustion apparatus according to the fourth aspect extinguishes the lean flame prior to extinguishing the fire, so that there is an effect that HC can be reduced by burning the lean mixture with the remaining rich flame.

Further, in the low NOx combustion apparatus according to the fifth aspect, the amount of air supplied to the light burner is limited at the time of ignition, so that the concentration of the air-fuel mixture is rapidly increased to form a flame that is stable on its own, and the HC is reduced. This has the effect of reducing discharge and increasing the heating rate.

Further, in the low NOx combustion apparatus according to the sixth aspect, the air supply to the light burner is limited prior to the extinguishing, so that the fuel remaining in the light burner is self-combustion with a stable flame. However, since the remainder is burned by the remaining rich flame, there is an effect that HC can be reduced.

[Brief description of the drawings]

FIG. 1 is an overall sectional diagram of a low NOx combustion device according to a first embodiment of the present invention.

FIG. 2 is a timing chart at the time of ignition of the apparatus.

FIG. 3 is a graph showing a mixture concentration progress at the time of ignition of the apparatus.

FIG. 4 is a diagram showing HC emission characteristics during ignition of the device.

FIG. 5 is a timing chart for extinguishing a low NOx combustion apparatus according to a second embodiment of the present invention.

FIG. 6 is a graph showing the progress of the mixture concentration at the time of extinguishing the apparatus.

FIG. 7 is a diagram showing HC emission characteristics of fire extinguishing of the apparatus.

FIG. 8 is an overall sectional view of a low NOx combustion device according to a third embodiment of the present invention.

FIG. 9 is a timing chart at the time of ignition of the apparatus.

FIG. 10 is a diagram showing a mixture concentration progress at the time of ignition of the apparatus.

FIG. 11 is a diagram showing HC emission characteristics during ignition of the device.

FIG. 12 is a timing chart at the time of extinguishing a low NOx combustion apparatus according to a fourth embodiment of the present invention.

FIG. 13 is a graph showing the progress of the mixture concentration at the time of extinguishing the apparatus.

FIG. 14 is a diagram showing HC emission characteristics of fire extinguishing of the apparatus.

FIG. 15 is a configuration diagram of a conventional low NOx combustion device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Rich burner 11 Light burner 12 Rich fuel supply system 13 Light fuel supply system 16 Light fuel control means 25 Control part 26 Light air supply system 31 Light air control means

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Chinori Aso 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] A fuel is burned by combining a rich flame generated by combustion of a rich air-fuel mixture and a light flame generated by combustion of a lean air-fuel mixture. Low NO characterized by burning
x combustion device. 2. A method of burning fuel by combining a rich flame generated by combustion of a rich air-fuel mixture and a light flame generated by combustion of a lean air-fuel mixture. Low NO characterized by burning
x combustion device. 3. A rich burner supplied with a rich air-fuel mixture to form a rich flame, a light burner supplied with a thin air-fuel mixture to form a light flame, and a rich burner for supplying fuel to the rich burner. A fuel supply system, a lean fuel supply system for supplying fuel to the lean burner, a lean fuel control means provided in the lean fuel supply system, and a control unit for controlling the lean fuel control means; This control unit controls the lean fuel control means so as to supply fuel to the lean fuel supply system with a delay from the rich fuel supply system at the time of ignition.
x combustion device. 4. A rich burner supplied with a rich air-fuel mixture to form a rich flame; a light burner supplied with a thin air-fuel mixture to form a light flame; and a rich burner for supplying fuel to said rich burner. A fuel supply system, a lean fuel supply system for supplying fuel to the lean burner, a lean fuel control means provided in the lean fuel supply system, and a control unit for controlling the lean fuel control means; The low NOx combustion device controls the lean fuel control means so as to shut off the fuel supply to the lean fuel supply system prior to the rich fuel supply system during fire extinguishing. 5. A rich burner which is supplied with a rich air-fuel mixture to form a rich flame, a light burner which is supplied with a thin air-fuel mixture and forms a light flame, and a rich burner which supplies fuel to said rich burner. A fuel supply system, a lean fuel supply system for supplying fuel to the lean burner, a lean air supply system for supplying air to the lean burner, and a lean air control means provided in the lean air supply system And a control unit for controlling the fresh air control means, wherein the control unit controls the fresh air control means so as to reduce the amount of air supplied to the fresh air supply system during ignition for a predetermined period. 6. A rich burner supplied with a rich air-fuel mixture to form a rich flame, a light burner supplied with a thin air-fuel mixture to form a light flame, and a rich burner for supplying fuel to said rich burner. A fuel supply system, a lean fuel supply system for supplying fuel to the lean burner, a lean air supply system for supplying air to the lean burner, and a lean air control means provided in the lean air supply system And a control unit for controlling the fresh air control means, wherein the control unit reduces the amount of air supplied to the fresh air supply system prior to stopping the fuel supply to the lean fuel supply system during fire extinguishing. A low NOx combustion device for controlling the fresh air control means.