JPH09137921A - Low-nox gas burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize excellent low-NOx combustion producing a reduced amount of CO, while suppressing occurrence of a flashback. SOLUTION: Gas burner having a construction wherein a plurality of burner bodies 5 each having a main burner port 8 in a main burner port forming surface 7 of a top part are juxtaposed in a burner case 3, with air-flow spaces 4 provided between, and a lean mixture gas being leaner than a mixture gas supplied to the burner bodies 5 is supplied to the air-flow spaces 4 between these burner bodies 5. In the respective upper parts of the air-flow spaces 4 between the burner bodies 5, sub-burner port plates 11 each having a large number of sub-burner ports 12 in a sub-burner port forming surface are provided. The height of the sub-burner port forming surface of the sub-burner port plate 11 is set to be lower than the main burner port forming surface 7 of the burner body 5, while the opposite end parts in the longitudinal direction thereof are held by a retainer plate 20 fitted to the upper part of the burner case 3 and a heat-resistant packing 22 is interposed between this retainer plate 20 and the sub-burner port forming surface of the sub-burner port plate 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas combustion apparatus used in a gas water heater, a gas hot water heater, etc.
The present invention relates to a low NOx gas combustion device that reduces the amount of Ox generated.

[0002]

2. Description of the Related Art In a conventional low NOx gas combustion apparatus of this type, as disclosed in, for example, Japanese Patent Application Laid-Open No. 6-331110, these are formed on both side walls of a main body having a main flame hole at the top. It is equipped with a sleeve-fire type burner body in which a pair of flame holding plates are erected while keeping both side walls and the flame holding space. Then, a plurality of burner bodies configured in this way are arranged side by side in the burner case with a mutual ventilation interval, and while supplying a slightly diluted mixed gas to the burner body, By supplying even more lean diluted mixed gas to the ventilation interval between the burner bodies, and by burning the lean mixed gas in multiple stages above this ventilation interval and above the burner body,
The amount of NOx generated was reduced.

[0003]

By the way, in the above-described low NOx gas combustion apparatus of the conventional structure, the upper open surface of the ventilation interval between the burner bodies, which is the outflow portion of the lean mixed gas, that is,
Since the area of the gap between the flame holding plates of the adjacent burner bodies is large, the amount of secondary air flowing through the ventilation interval between the burner bodies suddenly decreases, or the amount of gas flowing through the ventilation interval between the burner bodies suddenly increases. If it is increased to 1, the lean mixed gas state collapses to become a mixed gas that is easily ignited, and the flames formed above the ventilation interval and above the burner body are drawn into the ventilation interval between the burner bodies to cause flashback. There was a problem. Further, at the time of ignition, even if ignition is delayed, there is a problem that flashback occurs similarly.

Therefore, the inventors of the present invention can suppress the occurrence of flashback by providing each of the auxiliary flame hole plates having a large number of auxiliary flame holes on the auxiliary flame hole forming surface above the ventilation interval between the burner bodies. Although it was clarified, if the height position of the sub-flame plate is not properly set, not only will the combustion state become unstable, but also a holding plate and a sub-flame plate that hold both ends of the sub-flame plate in the longitudinal direction. When a gap is formed between the sub flame hole forming surface of the, a part of the lean mixed gas flowing through the air gap flows out from the gap, and the combustion state becomes unstable due to the lean mixed gas flowing out from the gap, There is a problem that the amount of CO generated increases due to incomplete combustion of the lean mixed gas flowing out from the gap.

The present invention has been made in view of the above circumstances, and it is possible to provide a low NOx gas combustion apparatus capable of realizing good low NOx combustion with a small amount of CO generation while suppressing the occurrence of flashback. The purpose is to do so.

[0006]

According to the present invention as set forth in claim 1, a plurality of burner bodies having main flame holes on the main flame hole forming surface at the top are arranged side by side in the burner case with a mutual ventilation interval. Then
In a gas combustion apparatus in which a lean mixed gas that is leaner than the mixed gas supplied to the burner body is supplied to the ventilation space between the burner bodies, a large number of sub-airs are provided above each ventilation space between the burner bodies. Sub flame hole plates each having a flame hole on the sub flame hole forming surface are provided, and the height of the sub flame hole forming surface is set lower than that of the main flame hole forming surface of the burner body. At the same time, both ends in the longitudinal direction are held by pressing plates attached to the upper part of the burner case, and heat-resistant packing is interposed between the pressing plate and the auxiliary flame hole forming surface of the auxiliary flame hole plate. It has a structure.

According to the second aspect of the present invention, a plurality of burner bodies having main flame holes on the main flame hole forming surface of the top are arranged in parallel in the burner case with a mutual air gap, and the space between these burner bodies is increased. In a gas combustor in which a lean mixed gas, which is leaner than the mixed gas supplied to the burner body, is supplied to the aeration intervals of, in the upper part of each ventilation interval between the burner bodies, a large number of secondary flame holes are Each of the auxiliary flame hole plates is provided on the flame hole forming surface, and the height of the auxiliary flame hole forming surface is set lower than that of the main flame hole forming surface of the burner body and the length thereof Both end portions in the direction are held by pressing plates attached to the upper part of the burner case, and heat-resistant packing is interposed between the pressing plate and the auxiliary flame hole forming surface of the auxiliary flame hole plate. A rising wall is integrally formed on the edge of the pressing plate on the burner side. Is a configuration that has been kicked.

According to the third aspect of the present invention, the height of the auxiliary flame hole forming surface of the auxiliary flame hole plate is set to be about 1 to 3 mm lower than that of the main flame hole forming surface of the burner body.

According to the fourth aspect of the present invention, the heat resistant packing is made of ceramic fiber.

In the low NOx gas combustion apparatus according to the first aspect of the present invention, a secondary flame having a large number of secondary flame holes on the secondary flame hole forming surface is provided above each ventilation interval between the burner bodies arranged in parallel in the burner case. Since the perforated plates are provided, if the amount of secondary air or gas flowing through each ventilation interval between the burner bodies suddenly increases or decreases and the lean mixed gas state collapses, or ignition delay occurs at ignition. In this case, a large number of secondary flame holes formed on the secondary flame hole forming surface of the secondary flame hole plate narrows the flame hole area for jetting the lean mixed gas, increasing the gas jetting speed. Flashback is suppressed.

Further, since the height of the sub-flame forming surface of each sub-flame plate is set to be lower than that of the main flame-forming surface of the burner body, the rare gas ejected from the sub-flame holes of each sub-flame plate is diluted. The flame holding property of the mixed gas is enhanced and stable combustion is achieved.

Further, each of the auxiliary flame hole plates is held at both longitudinal ends by pressing plates attached to the upper portion of the burner case, and the pressing plate and the auxiliary flame hole forming surface of the auxiliary flame hole plate are held. Since a heat-resistant packing is interposed between them, each sub-flame hole plate is securely fixed and held by the pressing plate and the heat-resistant packing, preventing displacement and rattling of each sub-flame plate due to impact during transportation. At the same time, the heat-resistant packing prevents the lean mixed gas from leaking between the pressing plate and the sub-flame forming surface of the sub-flame plate, so that the combustion state is further stabilized and the amount of CO generated is reduced.

In the low NOx gas combustion apparatus according to the second aspect of the present invention, since the rising plate is integrally provided with the rising wall at the edge of the burner body side, the strength of the pressing plate is improved and thermal deformation can be prevented. The rising wall can prevent the cooling air flowing outside the burner body from flowing toward the primary flame on the main burner hole of the burner body, so that the cooling air coming into contact with the primary flame causes C
O generation can be suppressed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 5, 1 is a blower, 2 is an outer casing to which combustion air is sent from the blower 1, and 3 is a burner case housed in the outer casing 2. In the burner case 3, a ventilation interval is provided. The secondary air passages 4 and 4 are provided, and the six burner bodies 5 and 5 are arranged in parallel. The burner case 3
Is divided into two left and right by a partition wall 3A provided upright in the middle thereof, and three burner bodies 5 and 5 are accommodated in the left and right chambers X and Y, respectively.

The burner bodies 5, 5 are provided with a large number of slit-shaped main flame holes 8, 8 on the main flame hole forming surface 7 at the top of the main body 5A in which the mixing chamber 6 is formed. And subject 5A
A pair of left and right flame holding plates 9 and 9 are erected on the upper portions of the left and right side walls while keeping the side walls and the flame holding spaces a and b.

In the flame-holding spaces a and b, a sleeve fire hole 1 is formed in which a part of the mixed gas supplied to the mixing chamber 6 is bored on the side wall.
The mixed gas that has entered through 0 and 10 rises in the flame holding spaces a and b and flows out, so that sleeve fire is formed on the flame holding spaces a and b. In addition, the upper end of each flame holding plate 9, 9 is approximately 2 times larger than the main flame hole forming surface 7.
The height is set so as to be lowered by ~ 4 mm.

The mixing chamber 6 of each burner body 5 is supplied with a slightly diluted mixed gas having an air ratio of about 1 to 1.3, and
The secondary air passages 4 and 4 between the burner bodies 5 and 5 are respectively supplied with a lean mixed gas that is more lean than the mixed gas supplied to the mixing chamber 6 of the burner body 5. The air ratio of the lean mixed gas supplied to the secondary air passages 4 and 4 is usually about 1.5 to 1.9.

Between the adjacent flame holding plates 9, 9 of the burner body 5, auxiliary flame hole plates 11, 11 each having a substantially U-shaped cross section are detachably installed. This secondary flame hole plate 11
3 and 5, as shown in FIGS. 3 and 5, a sub-flame hole forming surface 11A in which a large number of sub-flame holes 12 having a slit shape or a circular shape for jetting a lean mixed gas are formed in the longitudinal direction, Left and right side pieces 11B and 11C bent downward from both edges of the auxiliary flame hole forming surface 11A are provided.
By externally fitting B and 11C to the flame holding plates 9 and 9, the flame holding plates 9 are detachably attached from above the flame holding plate 9.

The sub-flame hole plate 11 is attached to the flame-holding plate 9, and the sub-flame hole forming surface 11A having the sub-flame holes 12 and 12 abutted on the upper end of the flame-holding plate 9 to cause the sub-flame. Hole forming surface 11A
The height position of is regulated. Then, this secondary flame hole formation surface 1
The height position of 1A is set lower than the main flame hole forming surface 7 of the burner body 5 by about 1 to 3 mm. In addition, each of the auxiliary flame holes 12 and 12 has a long side dimension of about 3 to 2.5 m.
m, the flame holding plates 9 and 9 adjacent to the burner body 5 are set.
It is equal to or smaller than the distance between them.

Further, both side pieces 11B of the auxiliary flame hole plate 11,
11C is provided with two or three protrusions 13 and 13 which are each protruded outward. And these protrusions 13, 1
3 is provided at a predetermined interval in the longitudinal direction of both side pieces 11B and 11C, and both side pieces 11B and 11C are connected to the flame holding plate 9
The height is set so that the tip of the burner body 5 comes into contact with the outer surface of the side wall of the burner body 5 when it is externally fitted.

Reference numeral 14 denotes an intermediate sub-flame plate having a substantially U-shaped cross section, which is provided above the secondary air passages 4A and 4A on both sides of the partition wall 3A. A large number of small holes 15 for ejecting a lean mixed gas having a diameter of about 1 mm
Are arranged in two rows along both sides in the longitudinal direction.

Sections 16 and 16 are provided on upper portions of the secondary air passages 4B and 4B between the side walls 3B and 3B of the burner case 3 and the burner bodies 5 and 5 adjacent to the side walls 3B and 3B. The end sub-flame plates 16 and 16 are substantially U-shaped, and the end sub-flame plates 16 and 16 have a large number of holes 17 and 17 having a diameter of about 1 mm for jetting a lean mixed gas in the longitudinal direction. They are arranged side by side in a line along the central portion. The end sub-flame hole plate 16 is externally fitted to the locking tool 18 mounted on the side wall 3B of the burner case 3 and the flame holding plate 9 of the burner body 5, thereby the locking tool 18 and the flame holding plate 9 are provided. It can be attached and removed freely from above.

Reference numerals 20 and 20 denote two screws 21 and 21 on the upper flange portions 3C and 3C of the burner case 3, respectively.
A pair of pressing plates that are fastened together by using the pressing plates 20 and 20. The pressing plates 20 and 20 are the auxiliary flame hole plates 11 and 11, the intermediate auxiliary flame hole plate 14, and the end auxiliary flame hole plates 16 and 16, respectively. Both ends in the longitudinal direction are pressed from above to be fixedly held, and are made of a heat-resistant steel plate such as a stainless steel plate having a plate thickness of about 1 mm. Then, between the pressing plates 20 and 20 and the auxiliary flame hole forming surface 11A of each of the auxiliary flame hole plates 11, the pressing plate 2 is provided.
0 and 20 and the upper surface of the intermediate auxiliary flame hole plate 14, and between the pressing plate 20 and the upper surface of the end auxiliary flame hole plate 16, as shown in FIGS. 22, 22
Is interposed. These heat resistant packings 22, 22
Is composed mainly of ceramic fibers made of alumina, silica, etc. and is molded using a non-combustible binder.
23 and 23 are upper flange portions 3C and 3C of the burner case 3.
Is a large number of cooling air ejection holes provided on the entire circumference of the.

Next, the fuel gas supply device 24 shown in FIG.
Will be described. In the fuel gas supply device 24, the original electromagnetic valve 25 and the proportional valve 26 are provided in the fuel gas supply path, and the first path 27 and the second path 27 are provided downstream of the proportional valve 26.
It is branched into two routes of route 28, and these first and second routes 2
Electromagnetic valves 29 and 30 are provided on the valves 7 and 28, respectively.

The first passage 27 branches off a third passage 31 on the downstream side of the solenoid valve 29, and the third passage 31 is connected to the secondary air passages 4, 4A, 4B in the room X on the left side of the burner case 3.
Is connected to the first auxiliary nozzle 32 that supplies the gas fuel to the first auxiliary nozzle 32, and the downstream side of the branch portion of the third path 31 supplies the gas fuel to the burner bodies 5 and 5 of the left chamber X of the burner case 3. Of the first main nozzles 33, 33.

The second path 28 branches a fourth path 34 on the downstream side of the solenoid valve 30, and the fourth path 34 is connected to the secondary air passages 4, 4A, 4B in the room Y on the right side of the burner case 3.
Is connected to the second auxiliary nozzle 35 that supplies the gas fuel to each of the burners, and the downstream side of the branch portion of the fourth path 34 supplies the gas fuel to the burner bodies 5 and 5 in the right room Y of the burner case 3. Of the second main nozzles 36, 36.

37 is an igniter such as a discharge spark plug,
In the igniter 37, the tip end of the ignition rod 37A is made to closely face the main flame hole forming surface 7 of one burner body 5 of the plurality of burner bodies 5 in the left chamber X of the burner case 3, Spark discharge is generated between the main flame hole forming surface 7.

Reference numeral 38 is a flame detector for detecting the presence or absence of a flame. The flame detector 38 has a frame rod 38A whose tip is provided with a plurality of auxiliary flame hole plates 11 in the left chamber X of the burner case 3.
One of the secondary flame hole plates 11 is closely opposed. 3
Reference numeral 9 denotes a control unit, which controls the opening / closing of the original solenoid valve 25, the proportional valve 26, and the solenoid valves 29, 30 as well as the ignition operation of the igniter 37 and the variable speed control of the blower 1. To control combustion.

In the above structure, a slightly diluted mixed gas having an air ratio of about 1 to 1.3 is supplied to the mixing chamber 6 of each burner body 5, and the secondary air between the burner bodies 5 and 5 is supplied. When a lean mixed gas having an air ratio of about 1.5 to 1.9 is supplied to the passages 4, 4A, and 4B, a part of the mixed gas supplied to the mixing chamber 6 of each burner body 5 is sleeve fire. The flame holding space (i) rises through the application holes (10, 10), and most of the rest flows toward the main flame holes (8, 8) and is ejected from the main flame holes (8, 8). On the other hand, the lean mixed gas supplied to the secondary air passages 4, 4A, 4B is
The secondary flame of each secondary flame hole plate 11 rises between adjacent flame holding plates 9 and 9, between the flame holding plate 9 and the partition wall 3A, between the flame holding plate 9 and the side wall 3B of the burner case 3, and the like. Holes 12, 12, small holes 15, 15 of the intermediate auxiliary flame hole plate 14, each end auxiliary flame hole plate 16, 16
It spouts from the holes 17, 17.

In the above state, when a spark is generated between the tip of the ignition rod 37A and the main flame hole surface 7 of the burner body 5, the mixed gas ejected from the main flame holes 8 and 8 is ignited, and this ignition The flame is transferred to the lean mixed gas ejected from the adjacent sub-flame holes 12 and 12, and the entire combustion is started. With the start of the whole combustion, a low-level flame (primary flame) is formed on the main flame holes 8 of each burner body 5, and a sleeve flame is formed on each flame holding space a. 5 above and the auxiliary flame hole plate 11,
A stable, large flame (secondary flame) having a high flame holding property is formed above the intermediate sub-flame hole plate 11, the intermediate sub-flame plate 14, and the end sub-flame plate 16, and a lean mixed gas with a small NOx generation amount is formed. Multi-stage combustion is performed.

At the time of strong combustion, the control unit 39 opens both of the solenoid valves 29, 30 so that all the burner bodies 5, 5 are discharged from the first main nozzles 33, 33 and the second main nozzles 36, 36. The gas fuel is supplied to the chambers X and Y on the left and right of the burner case 3 from the first auxiliary nozzle 32 and the second auxiliary nozzle 35. Also,
When the combustion state is switched from the strong combustion to the weak combustion with the reduced combustion amount, the control unit 39 closes the solenoid valve 30 although the solenoid valve 29 remains open, and the solenoid valve 3 is closed.
By closing 0, the supply of gas fuel from the second main nozzles 36, 36 is stopped, and the supply of gas fuel from the second auxiliary nozzle 35 is also stopped.

According to the present embodiment, the burner bodies 5, 5 having a large number of main flame holes 8, 8 on the main flame hole forming surface 7 at the top are connected to the secondary air passages 4, 4A, 4B (ventilation intervals). ) Are installed in parallel in the burner case 3, and the secondary air passages 4,
About 4A and 4B, about 1 is supplied to the mixing chamber 6 of the burner body 5.
In a gas combustor for supplying a lean mixed gas having an air ratio of about 1.5 to 1.9, which is leaner than a slightly lean mixed gas mixture of about 1.3 to 1.3, A large number of secondary flame holes 12, 1 are provided at the top of each secondary air passage 4, 4.
Since the sub-flame hole plates 11 and 11 that are formed on the sub-flame hole forming surface 11A are provided respectively, the amount of secondary air and the amount of gas flowing through the secondary air passages 4 and 4 between the burner bodies 5 and 5 are set. Suddenly increase or decrease and the state of the lean mixed gas collapses, and the air ratio is about 1
When a mixed gas that is close to the point of ignition and flows into the secondary air passages 4 and 4, or when an ignition delay occurs during ignition, a large number of holes formed on the auxiliary flame hole forming surface 11A of the auxiliary flame hole plate 11 The secondary flame holes 12, 12 narrow the flame hole area for jetting the lean mixed gas, and the gas jetting speed is increased, so that it is possible to suppress the backfire into the secondary air passages 4, 4.

Since the height of the auxiliary flame hole forming surface 11A of each auxiliary flame hole plate 11 is set lower than that of the main flame hole forming surface 7 of the burner body 5, the auxiliary flame holes 12 and 12 are formed. Since the lean mixed gas ejected from the flame is reliably held by the primary flame formed on the main flame hole forming surface 7 of the burner body 5, it is possible to maintain a stable and good combustion state, Setting the height of the auxiliary flame hole forming surface 11A of the flame hole plates 11, 11 lower than the main flame hole forming surface 7 of the burner body 5 by about 1 to 3 mm is optimal for stable combustion, and This is convenient in designing each sub-flame plate 11, 11.

Further, the respective auxiliary flame hole plates 11 and 11 have upper end portions 3C and 3C at the longitudinal end portions of the burner case 3 respectively.
It is fixed and held by a pair of pressing plates 20 and 20 which are fastened on C with screws 21 and 21, and between these pressing plates 20 and 20 and the auxiliary flame hole forming surface 11A of the auxiliary flame hole plate 11. Since heat-resistant packings 22 and 22 having ceramic fibers as a main component are interposed between the sub-flame plates 11 and 1,
1 is a pressing plate 20, 20 and heat resistant packing 22, 2
Both ends are securely fixed and held by 2, and the displacement and rattling of the sub flame hole plates 11 and 11 due to impact during transportation are prevented, and the heat-resistant packing 22 holds the pressing plate 20 and the sub flame hole plate 11 together. It is possible to prevent a part of the lean mixed gas from leaking from between the secondary flame hole forming surface 11A, a stable and favorable combustion state, and the amount of CO generated can be reduced.

The heat-resistant packing 22 is mainly composed of ceramic fibers such as alumina and silica,
Since it is molded using a non-flammable binder, it has a heat resistance of about 800 ° C or higher, and there is no fear of burning.

FIGS. 6 and 7 show another embodiment, and the same structural parts as those of the above-mentioned one embodiment are designated by the same reference numerals and the description thereof will be omitted.

40 and 40 are two screws 21 and 21 on the upper flange portions 3C and 3C of the burner case 3, respectively.
Are a pair of pressing plates fastened by using the pressing plates 40 and 40, which are the auxiliary flame hole plates 11 and 11, the intermediate auxiliary flame hole plate 14, and the end auxiliary flame hole plates 16 and 16, respectively. Both ends in the longitudinal direction are pressed from above to be fixedly held, and are made of a heat-resistant steel plate such as a stainless steel plate having a plate thickness of about 1 mm. Further, upright walls 41, 41 that are upright are integrally provided by bending at the inner edge portions of the pressing plates 40, 40 on the side of the burner bodies 5, 5.

According to this embodiment, the pressing plate 40,
40, since the rising walls 41, 41 are integrally formed by bending the inner edges of the burner bodies 5, 5 side, respectively, the strength of the pressing plate 40 is improved, thermal deformation can be prevented, and The rising wall 41 can prevent the cooling air that is ejected from the ejection holes 23, 23 and flows outside the burner bodies 5, 5 from flowing toward the primary flame on the main flame holes 8 of the burner body 5. The generation of CO due to the contact of the cooling air with the primary flame can be suppressed.

[0039]

According to the low NOx gas combustion apparatus of the first aspect of the present invention, a large number of auxiliary flame holes are formed on the auxiliary flame hole forming surface at the upper part of each ventilation interval between the burner bodies arranged in parallel in the burner case. Since the secondary flame holes are provided respectively, the amount of secondary air or gas flowing through each ventilation interval between the burner bodies suddenly increases or decreases and the lean mixed gas state collapses, or ignition delay occurs at ignition. In case of occurrence of, the number of sub-flame holes formed in the sub-flame plate forming surface of the sub-flame plate narrows the flame hole area for jetting the lean mixed gas and increases the gas jetting speed. In addition to suppressing the backfire to the inside, the height of the sub-flame forming surface of each sub-flame plate is set lower than that of the main flame forming surface of the burner body. It is possible to enhance the flame holding property of the lean mixed gas ejected from the sub-flame holes of the plate and to perform stable combustion.

Further, both ends of each sub flame hole plate in the longitudinal direction are held by pressing plates attached to the upper part of the burner case, and moreover, the pressing plate and the sub flame hole forming surface of the sub flame hole plate. Since a heat-resistant packing is interposed between them, each sub-flame hole plate can be securely fixed by the pressing plate and the heat-resistant packing, and displacement and rattling of each sub-flame plate due to impact during transportation can be prevented. At the same time, the heat-resistant packing prevents the lean mixed gas from leaking between the pressing plate and the sub-flame forming surface of the sub-flame plate, so that the combustion state is further stabilized and C
Good low NOx combustion with a small amount of O generation can be realized.

In the low NOx gas combustion apparatus according to the second aspect of the present invention, since the rising plate is integrally provided with the rising plate at the edge of the burner body side, the strength of the pressing plate is improved and thermal deformation can be prevented. The rising wall can prevent the cooling air flowing outside the burner body from flowing toward the primary flame on the main flame hole of the burner body, and the CO
Can be further suppressed.

[0042]

[Brief description of the drawings]

FIG. 1 is a plan view of a gas combustion device showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram similarly illustrating the overall configuration.

3 is a vertical sectional view taken along the line AA of FIG.

FIG. 4 is a vertical sectional view taken along line BB in FIG.

FIG. 5 is a perspective view of the same main portion.

FIG. 6 is a longitudinal sectional view of an essential part of another embodiment example corresponding to FIG.

FIG. 7 is a longitudinal sectional view of an essential part of another embodiment example corresponding to FIG.

[Explanation of symbols]

 3 Burner Case 4 Secondary Air Passage (Ventilation Interval) 5 Burner Body 7 Main Flame Hole Forming Surface 8 Main Flame Hole 11 Secondary Flame Hole Plate 11A Secondary Flame Hole Forming Surface 12 Secondary Flame Hole 20 Holding Plate 22 Heat Resistant Packing 40 Holding Plate 41 Rising wall

Claims (4)

[Claims] 1. A plurality of burner bodies having main flame holes on the main flame hole forming surface at the top are arranged side by side in a burner case with a mutual ventilation interval, and the burner body is provided in the ventilation interval between these burner bodies. In a gas combustion device adapted to supply a lean mixed gas that is leaner than the mixed gas to be supplied to the sub-flame, a sub-flame having a large number of sub-flame holes on a sub-flame hole forming surface is provided above each ventilation interval between the burner bodies. Each of the sub-flame plates has a height of the sub-flame hole forming surface lower than that of the main flame hole forming surface of the burner body, and both end portions in the longitudinal direction thereof are the burner case. It is held by the pressure plate attached to the top of
Further, a low NOx gas combustion apparatus characterized in that a heat-resistant packing is interposed between the pressing plate and the auxiliary flame forming surface of the auxiliary flame hole plate. 2. A plurality of burner bodies having main flame holes on the main flame hole forming surface at the top are arranged side by side in the burner case with a mutual ventilation interval, and the burner body is provided in the ventilation interval between the burner bodies. In a gas combustion device adapted to supply a lean mixed gas that is leaner than the mixed gas to be supplied to the above Each of the sub-flame plates has a height of the sub-flame hole forming surface lower than that of the main flame hole forming surface of the burner body, and both end portions in the longitudinal direction thereof are the burner case. It is held by the pressure plate attached to the top of
A heat-resistant packing is interposed between the pressing plate and the auxiliary flame forming surface of the auxiliary flame hole plate, and a rising wall is integrally provided at the edge of the pressing plate on the burner body side. A low NOx gas combustion device characterized by the above. 3. The height of the sub-flame forming surface of the sub-flame plate is set to be about 1 to 3 mm lower than that of the main-flame forming surface of the burner body. Low NOx gas combustion device. 4. The low NOx gas combustion apparatus according to claim 1, wherein the heat resistant packing is made of ceramic fiber.