JP2004225932A - Combustion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep the superior ignition property by preventing the sagging and bending of a spark rod in a combustion device wherein a combustion gas is ignited by sparking between spark and ground rods. <P>SOLUTION: In a single type regenerative burner 12, an outer periphery of the spark rod 28 is covered by an insulating body 29, an outer periphery of the insulating member 29 is covered by a conductive protection pipe 30, and they are fixed to a thermal storage body 14. The insulating member 29 and the protection pipe 30 are extended near an igniting position, and a tip of the spark rod 28 is further extended to a flame generating position. The combustion gas is ignited by the spark generated between the spark rod 28 and the protection pipe 30. A tip part of the spark rod 28 used also as the flame rod detects the generation of flame. As the spark rod 28 is protected by the insulating body 29 and the protection pipe 30, its sagging and bending can be prevented, and further the superior ignition proper can be kept as a clearance between the spark rod 28 and the protection pipe 30 can be kept constant by the insulating body 29. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
[Industrial applications]
The present invention relates to a combustion device provided with a spark rod for igniting combustion gas and a frame rod for detecting a flame.
[0002]
[Prior art]
A single-type heat storage burner is known as a combustion device for burning fuel gas. The single-type heat storage burner includes a single burner main body, a heat storage body having a plurality of supply / exhaust passages, an air supply blower, and a supply / exhaust switching valve device. By alternately circulating the supply and exhaust air in the passage and exchanging heat between the supply and exhaust, the air supply (combustion air) is preheated and the exhaust temperature is lowered, thereby increasing the thermal efficiency.
[0003]
An ignition and flame detection device in a conventional single-type heat storage burner will be described with reference to FIG. In the single-type heat storage burner 1 shown in FIG. 7, a burner main body 3 is attached to one end of a honeycomb-shaped heat storage body 2. A large number of supply / exhaust passages 4, fuel gas passages 5, and pilot air passages 6 are formed in the heat storage body 2 by its honeycomb shape. A plurality of supply / exhaust ports 7 communicating with the supply / exhaust passage 4 of the heat storage body 2 are arranged in the burner main body 3 along the circumferential direction, and a pilot passage 8 communicating with the fuel gas passage 5 and the pilot air passage 6. Are arranged in the center. A spark rod 9 is inserted into the center of the pilot passage 8. The base end of the spark rod 9 is inserted and fixed in the heat storage body 2. A pair of ground rods 10 are attached to the inner wall of the pilot passage 8 so as to oppose the tip of the spark rod 9 with a predetermined gap (spark gap) of about 2 to 3 mm. In FIG. 7, reference numeral 11 denotes a baffle plate for promoting mixing of fuel gas and pilot air.
[0004]
With this configuration, the fuel gas and the pilot air are supplied from the fuel gas passage 5 and the pilot air passage 6 of the regenerator 2 into the pilot passage 6, and the mixture thereof is sparked between the spark rod 9 and the ground rod 10. To ignite. Then, combustion air is supplied from some of the supply and exhaust ports 7 to perform combustion, and the exhaust gas after combustion is discharged from the remaining supply and exhaust ports 7. Then, the supply air (combustion air) and the exhaust gas are alternately passed through the supply / exhaust passage 4 of the heat storage body 2, and heat exchange is performed between the supply / exhaust air to increase the supply air temperature and to lower the exhaust gas temperature, thereby achieving thermal efficiency. Enhance.
[0005]
The spark rod 9 also serves as a flame rod for detecting a flame, and detects ignition and generation of a flame by detecting a current generated in the spark rod 9 (flame rod) by ions generated during combustion. can do. Thus, the ignition and flame detection device can be downsized by using the spark rod 9 also as the frame rod. Patent References 1 and 2 disclose a burner in which an ignition device and a flame detection device are integrated.
[0006]
[Patent Document 1]
JP-A-61-180834 [Patent Document 2]
JP-A-3-247914
[Problems to be solved by the invention]
However, the single-type heat storage burner 1 provided with the conventional ignition and flame detection device shown in FIG. 7 has the following problems.
In order to obtain a good spark in order to enhance the ignitability, it is necessary to keep the spark gap constant. In addition, as shown in FIG. 8, when sparking is performed between the tip end of the spark rod 9 and the ground rod 10, as shown in FIG. A better spark can be obtained than when sparking is performed.
[0008]
However, since the base end of the spark rod 9 is fixed to the heat storage body 2 and the distal end is a free end, the spark gap easily changes due to dripping or bending due to high temperature during combustion, and a good spark is generated. Difficult to maintain. On the other hand, it is conceivable to support the tip portion of the spark rod 9, but it is difficult to realize the problem because burnout of the support member becomes a problem.
[0009]
On the other hand, in order to increase the sensitivity of flame detection, it is necessary to lengthen the spark rod 9 (frame rod) and insert it as deep as possible into the flame. In this case, in order to spark at the tip of the spark rod 9, the ground rod 10 needs to be arranged on the downstream side exposed to the flame, which causes a problem of burning of the ground rod 10. Therefore, in practice, as shown in FIG. 9, the tip of the spark rod 9 is lengthened and inserted deeply into the flame, and the ground rod 10 is disposed on the upstream side to suppress burning by the flame. A spark is formed on the side surface of the ten.
[0010]
As a result, the spark gap changes due to the drooping or bending of the spark rod 9, so that it is not possible to obtain a good spark, and there is a problem that a misfire is easily caused. It is necessary to replace every three, and there is a problem that maintenance is poor.
[0011]
The present invention has been made in view of the above points, and an object of the present invention is to provide a combustion device that can prevent a spark rod from sagging or bending and maintain good ignitability.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is a combustion apparatus that ignites a fuel gas by sparking between a spark rod and a ground rod, wherein the spark rod has a base end supported and a tip end. The spark rod has a free end extending toward the ignition position, an outer periphery from the support portion to the vicinity of the ignition position is covered with an insulator, and an outer periphery of the insulator is covered with a protective tube. Is characterized in that a front end portion thereof extends from the insulator and the protective tube and also serves as a frame rod for detecting a flame.
With this configuration, ignition and flame detection are performed by the spark rod also serving as the frame rod, and the spark rod is supported by the insulator and the protection tube.
According to a second aspect of the present invention, in the combustion apparatus according to the first aspect, the protection tube also serves as the ground rod, and causes sparking between the spark rod and the protection tube. .
With such a configuration, the gap between the spark rod and the protective tube (spark gap) is kept constant by the insulator.
A combustion apparatus according to a third aspect of the present invention is a heat storage burner that, in addition to the configuration of the first or second aspect, alternately circulates combustion air and exhaust gas through the heat storage body and preheats the combustion air by heat exchange. The spark rod is supported by the heat storage body.
With such a configuration, the spark rod is supported by the insulator and the protection tube from the heat storage body to the vicinity of the ignition position.
A combustion apparatus according to a fourth aspect of the present invention is the combustion apparatus according to any one of the first to third aspects, further comprising a spark rod assembly having an integral structure including the spark rod, an insulator, and a protection tube. Can be attached to and detached from the support portion of the spark rod.
With this configuration, the spark rod, the insulator, and the protection tube can be integrally attached to and detached from the support portion.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
In the present embodiment, the combustion device according to the present invention is applied to a single-type heat storage burner. As shown in FIG. 1, the single-type heat storage burner 12 includes a burner main body 13, a heat storage body 14, and a supply / exhaust switch. And a valve device 15. The burner main body 13 has a cylindrical pilot passage 16 at the center thereof for passing fuel gas and pilot air, and a plurality (six in the illustrated example) of supply / exhaust arranged around the circumference along the circumferential direction. A mouth 17 is provided.
[0014]
The heat storage body 14 is a honeycomb structure that forms a number of passages having a hexagonal cross section along the axial direction, and has one end connected to the base end of the burner main body 13. A large number of passages of the heat storage body 14 form a supply / exhaust passage 18 communicating with each supply / exhaust port 17 of the burner body 13, a pilot air passage 19 communicating with the pilot passage 16, and a fuel gas passage 20. When high-temperature exhaust gas flows through many passages, heat is absorbed from the exhaust gas and heat is stored. When combustion air flows through these passages, heat is released and the combustion air is preheated to near the exhaust gas temperature.
[0015]
The air supply / exhaust switching valve device 15 is coupled to the other end of the heat storage body 14, and sequentially passes through the air supply / exhaust passage 18 of the heat storage body 14 that communicates with each air supply / exhaust port 17 of the burner body 13. A rotary valve 23 is connected to the port 22 and switches these connections alternately. The rotary valve 23 is driven by a motor 24 via gears 25 and 26, and connects a part of the supply / exhaust passage 18 (for example, one connected to two of the six supply / exhaust ports 17) to the intake port 21. At the same time, the rest (for example, those connected to the remaining four of the six supply / exhaust ports 17) are connected to the exhaust port 22, and the connection to the supply / exhaust ports 21 and 22 is sequentially switched in turn. . The air supply port 21 of the air supply / exhaust switching valve device 15 is connected to an air supply blower for supplying combustion air, and the exhaust port 22 is connected to an exhaust pipe for discharging exhaust gas.
[0016]
A spark rod assembly 27 is inserted through the center of the burner body 13, the heat storage body 14, and the supply / exhaust switching valve device 15 from the supply / exhaust switching valve device 15 side. As shown in FIGS. 2 and 3, the spark rod assembly 27 has an outer periphery of a spark rod 28 covered with an insulator 29, and an outer periphery of the insulator 29 covered with a conductive protective tube 30. The tip of the rod 28 protrudes from the insulator 29 and the protection tube 30. The insulator 29 can be made of ceramics having necessary insulation, heat resistance and strength, such as Al2O3 and MgO2. The protection tube 30 also serves as a ground rod for generating a spark with the spark rod 28, and may be, for example, a heat-resistant alloy based on nickel.
[0017]
The base end side of the protection pipe 30 is covered with a fuel gas pipe 31, and an annular gas passage 32 is formed between the protection pipe 30 and the fuel gas pipe 31. The fuel gas pipe 31 is fitted and fixed to a coupling member 33 fixed to the base end of the protection pipe 30, and the annular gas passage 32 communicates with a passage 34 formed in the coupling member 33. A power supply line 35 is connected to a terminal at a base end of the spark rod 28, and a power supply plate 36 is attached to a base end of the protective tube 30. The power supply plate 36 and the spark rod 28 are separated from each other by an insulating cover. Insulated by 37.
[0018]
The spark rod assembly 27 is inserted into the supply / exhaust switching valve device 15, the heat storage body 14, and the center of the burner main body 13, and the distal ends of the protection tube 30 and the fuel gas pipe 31 are fitted to the heat storage body 14, and The coupling member 33 is fitted and fixed to the case of the supply / exhaust switching valve device 15. The annular gas passage 32 communicates with the fuel gas passage 20 of the heat storage unit 14 and is connected to a fuel gas supply source via a passage 34 of the coupling member 33. The fuel gas pipe 31 is inserted into a pilot air pipe 38 provided in the supply / exhaust switching valve device 15 to form an annular air passage 39 between the fuel gas pipe 31 and the pilot air pipe 38. Is connected to a pilot air passage 19 of the heat storage unit 14 and is connected to an air supply blower via a passage 40 formed in the air supply / exhaust switching valve device 15.
[0019]
The distal end portions of the insulator 29 and the protection tube 30 are extended to near the ignition position in the pilot passage 16 of the burner body 13. The tip of the spark rod 28 extends from the insulator 29 and the tip of the protective tube 30, projects outward from the pilot passage 16 and extends to a flame generating position, and the spark rod 28 detects a flame. Also serves as a frame rod. In the pilot passage 16, a baffle plate 41 for appropriately mixing the fuel gas supplied from the fuel gas passage 20 of the heat storage unit 14 and the pilot air supplied from the pilot air passage 19 is provided.
[0020]
Next, the operation of the present embodiment configured as described above will be described.
The fuel gas from the fuel gas supply source is supplied into the pilot passage 16 of the burner body 13 via the passage 34, the annular gas passage 32, and the fuel gas passage 19. The pilot air from the air supply blower is supplied into the pilot passage 16 through the passage 40, the annular air passage 39, and the pilot air passage 19. By supplying power to the power supply line 35 and the power supply plate 36, a spark is generated between the spark rod 28 and the protection tube 30 to ignite a mixture of fuel gas and pilot air in the pilot passage 16.
[0021]
Combustion air from the air supply blower passes through an air supply port 21, a rotary valve 23, and a part of an air supply / exhaust passage 18, is supplied from a part of an air supply / exhaust port 17 of the burner main body 13 to the combustion space, and Burn the gas. At the same time, the exhaust gas after combustion passes through the remaining supply / exhaust port 17 and supply / exhaust passage 18 and is discharged from the exhaust port 22 via the rotary valve 23. At this time, the combustion air and the exhaust gas are alternately passed through the supply / exhaust passage 18 of the heat storage unit 14 by the rotary valve 23, and heat is exchanged between the supply / exhaust air to preheat the combustion air and to reduce the exhaust gas temperature. Reduce the thermal efficiency.
[0022]
After the ignition of the fuel gas, the generation of a flame is detected based on the current generated in the spark rod 28 by the ions generated during combustion by monitoring the current generated in the spark rod 28 also serving as the flame rod.
[0023]
In the pilot passage 16, the spark rod 28 is supported and protected by the insulator 29 and the protection tube 30, so that it does not bend or sag even when exposed to a flame. Thus, the tip of the spark rod 28 can be inserted deeply into the flame, and the flame detection sensitivity can be increased. Even if the tip of the spark rod protruding from the insulator 29 and the protection tube 30 is deformed, the spark gap between the spark rod 28 and the protection tube 30 also serving as a ground rod is maintained constant by the insulator 29. , Good ignitability can be ensured. Since the insulator 29 is covered and protected by the protective tube 30, it is hard to be damaged, and even if it is damaged, it does not fall off and the insulation can be maintained.
[0024]
The spark rod assembly 27 is formed by integrating the spark rod 28 also serving as a frame rod, the protective tube 30 also serving as a ground rod, and the insulator 29 therebetween, whereby the size can be reduced. Further, when the protection tube 30 or the spark rod 28 is deteriorated due to burnout or the like, the spark rod assembly 27 can be easily replaced, and the burner main body 13 and the like do not need to be replaced.
[0025]
The spark generation position (ignition position) can be adjusted only by changing the lengths of the insulator 29 and the protection tube 30 without replacing the burner body 13, so that the spark generation position can be easily adjusted according to the ignition limit range of the air-fuel mixture. Thus, the spark generation position can be adjusted, and reliable ignition can be performed. In this case, the spark generation position and the flame detection position can be adjusted by making the spark rod 28, the insulator 29, and the protection tube 30 movable and expanding and contracting.
[0026]
In the above embodiment, as shown in FIG. 4, when the outer diameter of the insulator 29 of the spark rod assembly 27 is large, the distal end of the protective tube 30 is extended inward to reduce the diameter, or is projected inward to protrude. By forming the portion 30A, the gap between the spark rod 28 and the protective tube 30 can be reduced, and the spark gap S can be adjusted.
[0027]
Further, as shown in FIG. 5, when the outer diameter of the insulator 29 is small, the gap between the spark rod 28 and the protective tube 30 can be increased by projecting the insulator 29 from the tip of the protective tube 30. Thus, the spark gap S can be adjusted.
[0028]
In the above-described embodiment, the spark is formed between the spark rod 28 and the protection tube 30. However, as shown in FIG. It is also possible to provide a spark between the spark rod 28 and the ground rod 42 as in the above-described conventional example. In this case, the spark rod 28 can be reliably supported by the insulator 29 and the protection tube 30, and the fluctuation of the spark gap due to the deformation of the spark rod 20 can be suppressed. However, since the ground rod 42 is separate from the spark rod assembly 27, the same measures as in the above-described conventional example are required for burnout of the ground rod 42.
[0029]
【The invention's effect】
As described in detail above, according to the combustion device of the present invention, it is possible to prevent the spark rod from sagging or bending, and to maintain good ignitability.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a single-type heat storage burner according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of a spark rod assembly of the apparatus shown in FIG.
FIG. 3 is an enlarged view of a distal end portion of the spark rod assembly shown in FIG. 2;
FIG. 4 is an enlarged view showing a modification of the distal end portion of the spark rod assembly shown in FIG.
FIG. 5 is an enlarged view showing another modification of the distal end portion of the spark rod assembly shown in FIG.
FIG. 6 is an enlarged view of a pilot passage portion showing a modification in which a ground rod is provided in the pilot passage in the device shown in FIG.
FIG. 7 is a longitudinal sectional view of a tip portion of a conventional single-type heat storage burner.
8 is an enlarged schematic view showing an ignition portion when sparking is caused between the tip of the spark rod and the ground rod in the conventional example shown in FIG.
FIG. 9 is a schematic diagram showing, in an enlarged manner, an ignition portion in the case of sparking between the side portion of the spark rod and the ground rod in the conventional example shown in FIG.
[Explanation of symbols]
12 Single type heat storage burner (combustion device)
14 Thermal Storage 27 Spark Rod Assembly 28 Spark Rod 29 Insulator 30 Protection Tube

Claims (4)

In a combustion device that ignites a fuel gas by sparking between a spark rod and a ground rod, the spark rod has a base end supported, a distal end set as a free end and extended toward an ignition position, and a support portion. To the vicinity of the ignition position are covered with an insulator, and furthermore, the outer periphery of the insulator is covered with a protective tube, and the tip of the spark rod is extended from the insulator and the protective tube to form a flame. A combustion device characterized in that it also serves as a frame rod for detecting the pressure. 2. The combustion apparatus according to claim 1, wherein the protection tube also serves as the ground rod, and causes sparking between the spark rod and the protection tube. 3. 2. A heat storage burner for preheating the combustion air by heat exchange by alternately circulating combustion air and exhaust gas through the heat accumulator, wherein the spark rod is supported by the heat accumulator. Or the combustion device according to 2. 4. The spark rod assembly according to claim 1, further comprising a spark rod assembly having an integral structure including the spark rod, an insulator, and a protection tube, wherein the spark rod assembly is detachable from a support portion of the spark rod. A combustion device according to any one of the above.

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