JP3272239B2 - Low NOx gas combustion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low NOx gas combustion apparatus used in a gas water heater, a gas hot water heater, or the like, and in which the amount of generated NOx is reduced.

[0002]

2. Description of the Related Art In a conventional gas combustion apparatus of this type, for example, as disclosed in Japanese Patent Application Laid-Open No. Hei 6-331110, both sides of a main body having a main flame hole at the top are provided on both sides.
A sleeve-fire type burner body is provided with a pair of flame-holding plates erected while maintaining these side walls and the flame-holding space. Then, a plurality of the burners configured as described above are arranged side by side in the burner case with a ventilation interval therebetween, and a slightly diluted mixed gas is supplied to the burner, and the mixed gas supplied to the burner is The lean mixed gas is supplied to the ventilation gap between the burners, and the lean mixed gas is multi-stage burned above the ventilation gap and above the burner to obtain NOx.
Was reduced.

[0003]

In the above-described conventional gas combustion apparatus, the upper open surface of the ventilation space between the burners, which is the outlet of the lean mixed gas, that is, the flame holding plate of the adjacent burner. When the amount of secondary air flowing through the ventilation gap between the burner bodies suddenly decreases or the amount of gas flowing through the ventilation gap between the burner bodies suddenly increases due to the large area of the gap between There is a problem that the gas state collapses and the mixture gas becomes easily ignitable, and the flame formed above the ventilation gap and above the burner body is drawn into the ventilation gap between the burner bodies, causing flashback. Further, at the time of ignition, even if ignition is delayed, there is a problem that flashback occurs similarly.

[0004] The present invention has been made in view of the above-described circumstances, and is intended to prevent sudden fluctuations in the amount of gas flowing through the ventilation gap between burners and the occurrence of flashback due to ignition delay during ignition. It is intended to perform stable low NOx combustion with low noise while suppressing the noise.

[0005]

According to the first aspect of the present invention, a plurality of burners having a main flame hole at the top are arranged side by side in a burner case with a ventilation space therebetween. In the gas combustion device to which a mixed gas that is more dilute than the mixed gas supplied to the burner body is supplied, a large number of auxiliary gas jetting the diluted mixed gas are provided above the ventilation gap between the burner bodies. This is a configuration in which an auxiliary flame hole plate having flame holes arranged in the longitudinal direction is arranged, and a rectifying member formed of a honeycomb formed body is arranged below the auxiliary flame hole plate.

According to the second aspect of the present invention, a plurality of burners having a main flame hole at the top are arranged side by side in a burner case with a ventilation space therebetween. In a gas combustion device in which a lean gas mixture is supplied which is more dilute than the gas mixture supplied to the burner body, a number of auxiliary flame holes for ejecting the lean gas mixture are formed in a longitudinal direction above the ventilation gap between the burner bodies. Along with the arranged auxiliary flame hole plates, a rectifying member formed of a honeycomb formed body is arranged below the auxiliary flame hole plate, and further, a ventilation resistance plate having a plurality of slits is arranged under the rectifying member. This is the configuration.

According to the third aspect of the present invention, a plurality of burners having a main flame hole at the top are arranged side by side in a burner case with a ventilation space therebetween. In a gas combustion device in which a lean gas mixture is supplied which is more dilute than the gas mixture supplied to the burner body, a number of auxiliary flame holes for ejecting the lean gas mixture are formed in a longitudinal direction above the ventilation gap between the burner bodies. In addition to arranging the sub-flame perforated plates arranged side by side, a rectifying member made of a honeycomb formed body is arranged below the sub-flame perforated plate, and the sub-flame perforated plate is positioned at an intermediate position in a longitudinal direction thereof. This is a configuration in which a fire transfer portion without a hole is formed.

In the low NOx gas combustion apparatus according to the first aspect, a sub-flame hole plate in which a number of sub-flame holes for jetting a lean mixed gas are arranged in the longitudinal direction is disposed above the ventilation gap between the burners. In addition, since the rectifying member made of a honeycomb formed body is arranged below the auxiliary flame hole plate, a large number of auxiliary flame holes arranged in the auxiliary flame hole plate provide a flame hole area for ejecting a lean mixed gas. It is possible to adjust as appropriate, such as narrowing, so that flashback into the ventilation interval is not only suppressed, but also the flow of the lean mixed gas flowing through the ventilation interval is rectified by the rectifying member, and then ejected from the auxiliary flame hole Therefore, stable low NOx combustion with low noise can be performed.

In the low NOx gas combustion apparatus according to the second aspect, a sub-flame hole plate in which a number of sub-flame holes for jetting a lean mixed gas are arranged in the longitudinal direction above the ventilation space between the burners. In addition, a rectifying member made of a honeycomb formed body is arranged below the auxiliary flame hole plate, and furthermore, a ventilation resistance plate having a plurality of slits is arranged below the rectifying member, so that the airflow resistance is within the ventilation interval. Of the mixed gas flowing through the intermediate portion within the ventilation interval can be increased by the slits of the ventilation resistance plate, while realizing low noise and stable low NOx combustion. Flashback to the lower part in the interval is also reliably prevented.

[0010] In the low NOx gas combustion apparatus according to the third aspect, a sub-flame hole plate in which a number of sub-flame holes for jetting a lean mixed gas are arranged in the longitudinal direction is disposed above the ventilation gap between the burners. At the same time, a rectifying member formed of a honeycomb formed body is disposed below the auxiliary flame hole plate, and a fire transfer portion having no auxiliary flame hole is formed at an intermediate position in the longitudinal direction of the auxiliary flame hole plate. Therefore, flashback into the ventilation interval is suppressed, and low noise and stable low NOx combustion can be realized, and good fire transfer to the adjacent burner body can be achieved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 7, reference numeral 1 denotes a blower, 2 denotes an outer case into which combustion air is sent from the blower 1, 3 denotes a burner case housed in the outer case 2, and a ventilation space is provided in the burner case 3. Are provided, and six burner bodies 5, 5 are juxtaposed. The burner case 3
Is divided into right and left by a partition wall 3A erected at an intermediate portion thereof, and the left and right rooms X and Y accommodate the three burner bodies 5, 5 respectively.

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

A part of the mixed gas supplied to the mixing chamber 6 enters the flame holding spaces A through the sleeve fire holes 10 formed in the upper portions of the left and right side walls of the main body 5A. The mixed gas thus entered rises and flows out of the flame holding spaces A and A, and a sleeve flame is formed on the flame holding spaces A and A. The height of each of the flame stabilizing plates 9, 9 is set so that the upper end thereof is lower than the main flame hole forming surface 7 by about 2 to 4 mm. The burner body 5 has a part of the mixed gas supplied to the mixing chamber 6 of the burner body 5 toward the secondary air passage 4 on the left and right side walls below the flame holding space A, A. A plurality of mixed gas ejection holes 11 and 1
1 are pierced side by side at appropriate intervals, and the diameter of each of the plurality of mixed gas ejection holes 11 is set to about 1 mm.

A slightly dilute mixed gas having an air ratio of about 1 to 1.3 is supplied to the mixing chamber 6 of each burner body 5.
A lower mixed gas supplied to the mixing chamber 6 of the burner body 5 is supplied to a lower portion in the secondary air passages 4 between the respective burner bodies 5 and 5 so as to be supplied respectively. Has become. The air ratio of the lean gas mixture supplied to the secondary air passages 4 is usually about 1.8 to 2.5.

Between the flame-holding plates 9, 9 adjacent to the burner body 5, auxiliary flame-perforated plates 12, 12 each having a substantially U-shaped section are detachably mounted. This auxiliary flame hole plate 12
Is a sub-flame hole forming surface 12A in which a number of slit-shaped or circular appropriate shaped sub-flame holes 13 for ejecting a lean mixed gas are formed in the longitudinal direction, and both edges of the sub-flame hole forming surface 12A. And left and right side pieces 12B and 12C bent downward from above.
By externally fitting to the flame holding plate 9, it is attached to the flame holding plate 9 so that it can be freely inserted and removed from above the flame holding plate 9.

When the auxiliary flame hole plate 12 is attached to the flame holding plate 9, the auxiliary flame hole forming surface 12 A formed with the auxiliary flame holes 13 abuts on the upper end of the flame holding plate 9. Hole forming surface 12A
Height position is regulated. Then, the secondary flame hole forming surface 1
The height position of 2A is set about 1 to 3 mm lower than the main flame hole forming surface 7 of the burner body 5.

Reference numeral 14 denotes an intermediate auxiliary flame hole plate having a substantially U-shaped cross section provided at the upper part of the secondary air passages 4A, 4A on both sides of the partition wall 3A. About 1m
A small hole forming surface 14A formed by arranging a number of small holes 15 for ejecting a lean mixed gas of m in two rows along both sides in the longitudinal direction, and downward from both edges of the small hole forming surface 14A. The left and right side pieces 14B and 14C are bent to form a partition by externally fitting the two side pieces 14B and 14C to the flame holding plate 9.9 of the burner bodies 5 and 5 adjacent to the partition wall 3A. The partition 3A is provided so as to cover the wall 3A from above. And, each of the auxiliary flame perforated plates 12
A non-aperture portion a as a fire transfer portion without an auxiliary flame hole 13 is formed at a substantially central portion in a longitudinal direction of the auxiliary flame hole forming surface 12A, and the intermediate auxiliary flame hole plate 14 is At a substantially central portion in the longitudinal direction of the small hole forming surface 14A, a non-porous portion c as a fire transfer portion having no small hole 15 is formed.

Reference numerals 16 and 16 denote ends provided on the 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. And the end auxiliary flame perforated plate 16,
Reference numeral 16 denotes a large number of holes 17 having a diameter of about 1 mm for jetting a rare gas mixture, which are formed in a row along a central portion in the longitudinal direction.

Next, the fuel gas supply device 20 shown in FIG.
Will be described. The fuel gas supply device 20 includes a primary solenoid valve 21 and a proportional valve 22 interposed in a fuel gas supply path, and a first path 23 and a second path
The path branches into two paths of a path 24, and the first and second paths 2
Electromagnetic valves 25 and 26 are interposed in 3 and 24, respectively.

The first path 23 branches off a third path 27 downstream of the solenoid valve 25, and connects the third path 27 to the secondary air passages 4, 4 A, 4 B of the left room X of the burner case 3.
Connected to a first auxiliary nozzle 28 for supplying gaseous fuel to the burner case 3, and a downstream side of the branch of the third path 27 for supplying gaseous fuel to each burner body 5, 5 in the room X on the left side of the burner case 3. Are connected to the first main nozzles 29, 29.

The second path 24 branches the fourth path 30 downstream of the solenoid valve 26, and connects the fourth path 30 to the secondary air passages 4, 4 A, 4 B in the right room Y of the burner case 3.
Connected to the second auxiliary nozzle 31 for supplying gaseous fuel to the burner case 3, and the downstream side of the branch of the fourth path 30 for supplying gaseous fuel to each burner body 5, 5 in the right room Y of the burner case 3. Are connected to the second main nozzles 32, 32. 3
Reference numeral 3 denotes an igniter such as a discharge spark plug or the like; 34, a flame detector for detecting the presence or absence of a flame; and 35, a control unit. This control unit 35 opens and closes the original solenoid valve 21, the proportional valve 22, and the solenoid valves 25, 26. And the ignition operation of the igniter 33 and the blower 1
The combustion speed is controlled by performing the variable speed control. 38, 38
Numerals are a large number of air ejection holes provided on the entire periphery of the upper part of the burner case 3.

Reference numerals 39, 39 denote ventilation resistance plates interposed at intermediate positions of the secondary air passages 4, 4 upstream of the mixed gas ejection hole 11 of the burner body 5, respectively. As shown in FIGS. 3 and 7, as shown in FIGS. 3 and 7, substantially vertical opposing walls 39A, 39A whose lower ends are connected and which face each other with an interval of about 2 to 3 mm are provided.
A, a support plate portion 39B, 39B having a substantially L-shaped cross section projecting outward from the upper end of 39A is formed by bending one sheet of stainless steel, and a part of the support plate portion 39B, 3 Are brought into contact with the burner bodies 5 and 5 so as to be stably held between the burner bodies 5 and 5. Further, each of the opposed walls 39A, 39A
In the middle position, a number of vertical slits 40, 40 are formed side by side at predetermined intervals, and the total opening area of the vertical slits 40, 40 of one ventilation resistance plate 39 is one auxiliary flame. It is set to be equal to or less than the total opening area of the auxiliary flame holes 13 of the perforated plate 12. The vertical slit 40 has a vertical dimension of about 8 to 10 mm and a horizontal dimension of about 0.5 to 0.8 m.

Reference numerals 41, 41 denote the auxiliary flame hole forming surface 12A of the auxiliary flame hole plate 12 and the support plate portions 39B, 39 of the ventilation resistance plate 39.
B, and rectifying members disposed in each of the secondary air passages 4, 4. These rectifying members 41, 41 are, as shown in FIGS. 5 and 6, two stainless corrugated plates. 41
A and 41A are made of a honeycomb formed body, and an upper half thereof is interposed and held between the flame holding plates 9.9 and a lower end thereof is close to the ventilation resistance plate 39 as shown in FIG. are doing.

In the above configuration, a slightly diluted mixed gas having an air ratio of about 1 to 1.3 is supplied to the mixing chamber 6 of each of the burner bodies 5, and the secondary air between the burner bodies 5 and 5 is supplied. The lower part of the passages 4, 4A, 4B has an air ratio of about 1.8-2.
When the super-lean mixed gas 5 is supplied, a part of the mixed gas supplied to the mixing chamber 6 of each burner body 5 is ejected to the secondary air passage 4 through the mixed gas ejection hole 11 and , Flows out to the flame holding space a through the sleeve fire holes 10 and 10,
Most of the rest flows toward the main flame holes 8 and gushes out of the main flame holes 8. On the other hand, the ultra-lean mixed gas having an air ratio of about 1.8 to 2.5 supplied to the lower part of the secondary air passages 4 and 4 is supplied to the vertical slits 40 and
After passing through the passage 40, the passages of the flow regulating members 41, 41 are ascended and mixed with a mixed gas having an air ratio of about 1 to 1.3 ejected from the mixed gas ejection hole 11, so that the air ratio is about 1. 5
The gaseous mixture becomes a diluted mixed gas of about 2.2 and is ejected from the auxiliary flame holes 13 of the auxiliary flame hole plate 12. Also, the secondary air passages 4A, 4A,
A, 4B, the air ratio supplied to the lower part of 4B is about 1.
The super-lean mixed gas of 8 to 2.5 is supplied to these secondary air passages 4.
A and 4B are raised and mixed with a mixed gas having an air ratio of about 1 to 1.3 ejected from the mixed gas ejection hole 11 to become a lean mixed gas having an air ratio of about 1.5 to 2.2. Flame plate 1
4 small holes 15, 15, each end secondary flame hole plate 16, 16 holes 1
It gushes from 7,17.

When a spark is generated in the igniter 33 in the above-described state, the mixed gas ejected from the main flame holes 8, 8 ignites, and the ignition flame emits the lean mixed gas ejected from the adjacent auxiliary flame holes 13, 13. The gas burns and the whole combustion starts. When the entire combustion starts, a low-height flame (primary flame) is formed on the main flame hole 8 of each burner body 5, and a sleeve flame is formed on each flame holding space A. A large flame (secondary flame) having a high flame-holding property is formed in a continuous manner above the upper part 5 and above the auxiliary flame-perforated plates 12, 12, the intermediate auxiliary flame-perforated plate 14, and the end-side flame-perforated plate 16. Then, multi-stage lean mixed gas combustion with a small NOx generation amount is performed.

At the time of strong combustion, the control unit 35 opens both of the solenoid valves 25 and 26 so that the first main nozzles 29 and 29 and the second main nozzles 32 and 32 can output all the burners 5 and 5. The gas fuel is supplied to the left and right rooms X and Y of the burner case 3 from the first auxiliary nozzle 28 and the second auxiliary nozzle 31. Also,
When the combustion state is switched from strong combustion to weak combustion in which the amount of combustion is reduced, the electromagnetic valve 25 is kept open but the electromagnetic valve 26 is closed by the control unit 35, and the electromagnetic valve 2 is closed.
Due to the blockage of 6, the supply of gas fuel from the second main nozzles 32, 32 is stopped, and the supply of gas fuel from the second auxiliary nozzle 31 is also stopped. Therefore, the burner bodies 5, 5 installed in the right room Y of the burner case 3, and
Gas fuel is not supplied to the secondary air passages 4, 4A, 4B of the right room Y, and gas leakage is performed by switching the number of burners to be burned while performing multi-stage lean mixed gas combustion with a small NOx generation amount. The burning width can be increased without worry.

According to this embodiment, the burner body 5 having a large number of main flame holes 8, 8 on the top main flame hole forming surface 7 is provided with the secondary air passages 4, 4A, 4B (ventilation intervals). 6 in the burner case 3 and the secondary air passages 4, 4
In the lower part inside A and 4B, there is a gas combustion device that supplies a mixed gas that is more dilute than the mixed gas supplied to the mixing chamber 6 of the burner body 5. At the upper part of the next air passages 4, 4, the auxiliary flame hole plates 12, 12 having a large number of auxiliary flame holes 13 for ejecting the lean mixed gas on the auxiliary flame hole forming surface 12A are arranged. 1
Since the rectifying members 41, 41 made of a honeycomb formed body in which two stainless corrugated plates 41A, 41A are stacked under the secondary flame hole forming surface 12A, the secondary flame hole plate 12 is formed. The number of auxiliary flame holes 13 arranged in the auxiliary flame hole forming surface 12A makes it possible to reduce the area of the flame hole for injecting the lean mixed gas as compared with the conventional art so as to increase the ejection speed, and to increase the secondary air passage. 4 is suppressed, and the amount of mixed gas flowing through each of the secondary air passages 4, 4 </ b> A, 4 </ b> B fluctuates abruptly, and an ignition delay occurs at the time of ignition that generates a spark of the igniter 33. In this case, flashback into each of the secondary air passages 4, 4A and 4B can be suppressed,
After the flow of the lean mixed gas flowing through the secondary air passage 4 is rectified by the rectifying member 41, the gas can be ejected from the auxiliary flame holes 13 of the auxiliary flame hole plate 12. The mixed lean gas multi-stage combustion can be performed.

Further, in the secondary air passage 4 below the rectifying members 41, 41, a ventilation resistance plate 39 having a large number of longitudinal slits 40, 40 at an intermediate position between the opposing walls 39A, 39A is arranged. The flow rate of the lean gas mixture flowing at the intermediate height position of the secondary air passage 4 can be increased by the vertical slits 40 of the ventilation resistance plate 39, and the flashback to the lower part in the secondary air passage 4 is also ensured. Can be prevented.

Each of the sub-flame hole plates 12 has a sub-flame hole 13 at a substantially central portion in the longitudinal direction of the sub-fire hole forming surface 12A.
Non-perforated portions a and a are formed as a non-fire transfer portion, and the intermediate auxiliary flame perforated plate 14 has a small hole forming surface 14A thereof.
A non-perforated portion c as a fire transfer portion having no small hole 15 is formed at a substantially central portion in the longitudinal direction of the burner body 5, and a fire is applied to the adjacent burner bodies 5, 5 through these non-perforated portions a, a, c. The transfer can be performed instantaneously, and the danger of the raw gas being released due to the delay of the fire transfer can be avoided.

[0030]

In the low NOx gas combustion apparatus according to the first aspect of the present invention, a sub-flame hole plate in which a number of sub-flame holes for jetting a lean mixed gas are arranged in the longitudinal direction above the ventilation gap between the burners. In addition to the arrangement, a rectifying member made of a honeycomb formed body is arranged below the auxiliary flame hole plate, so that a large number of auxiliary flame holes arranged in the auxiliary flame hole plate allow the flame for ejecting a lean mixed gas to be discharged. The hole area can be narrowed, so that flashback into the ventilation gap is suppressed, and of course, after the flow of the lean mixed gas flowing through the ventilation gap is rectified by the rectification member, Since the fuel gas can be injected, the amount of generated NOx is small, and low-noise, stable mixed gas multi-stage combustion can be performed. Therefore, sudden fluctuations in the amount of gas flowing through the ventilation space between the burner bodies can be performed. Or flashback caused by ignition delay at the time of ignition While suppressing, it can realize stable, low NOx combustion with low noise.

In the low NOx gas combustion apparatus according to the second aspect, a sub-flame hole plate in which a number of sub-flame holes for ejecting a lean mixed gas are arranged in the longitudinal direction is disposed above the ventilation gap between the burners. At the same time, a rectifying member made of a honeycomb formed body is arranged below the auxiliary flame hole plate, and further, a ventilation resistance plate having a plurality of slits is arranged below the rectifying member, so Of the mixed gas flowing through the intermediate portion within the ventilation interval can be increased by the slits of the ventilation resistance plate, while realizing low noise and stable low NOx combustion. Flashback to the lower part in the interval is reliably prevented, and safety can be further enhanced.

In the low NOx gas combustion apparatus according to the third aspect, a sub-flame hole plate in which a number of sub-flame holes for ejecting a lean mixed gas are arranged in the longitudinal direction is disposed above the ventilation gap between the burners. At the same time, a rectifying member formed of a honeycomb formed body is disposed below the auxiliary flame hole plate, and a fire transfer portion having no auxiliary flame hole is formed at an intermediate position in the longitudinal direction of the auxiliary flame hole plate. As a result, flashback into the ventilation space is suppressed, and low noise and stable low NOx combustion can be achieved, while good fire transfer to the adjacent burner body can be achieved. The risk of releasing raw gas can be avoided.

[Brief description of the drawings]

FIG. 1 is a plan view of a low NOx gas combustion apparatus showing one embodiment of the present invention.

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

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

FIG. 4 is an enlarged plan view of a relevant part.

FIG. 5 is an enlarged plan view of a main part in a state where one auxiliary flame hole plate is removed.

FIG. 6 is a perspective view of a part of the rectifying member.

FIG. 7 is a side view and a front view of the ventilation resistance plate.

[Explanation of symbols]

 Reference Signs List 3 burner case 4 secondary air passage (ventilation interval) 5 burner body 8 main flame hole 12 sub flame hole plate 13 sub flame hole 39 ventilation resistance plate 40 vertical slit (slit) 41 rectifying member a non-porous portion of sub flame hole plate (Fire transfer section)

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-151316 (JP, A) JP-A-7-127818 (JP, A) JP-A-6-331110 (JP, A) JP-A-7-151 103422 (JP, A) JP-A-9-137921 (JP, A) JP-A-6-46131 (JP, U) JP-A-5-45419 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23D 14/02-14/10 F23C 11/00 329-329

Claims (3)

(57) [Claims] 1. A plurality of burners having a main flame hole at the top are arranged side by side in a burner case with a ventilation space therebetween, and a mixed gas supplied to the burner is provided in the ventilation space between the burners. In a gas combustion apparatus to which a leaner mixed gas is supplied, a secondary flame hole plate in which a number of secondary flame holes for ejecting the lean mixed gas are arranged in the longitudinal direction at the upper part of the ventilation gap between the burners. A low NOx gas combustion device, wherein a rectifying member formed of a honeycomb formed body is disposed below the auxiliary flame hole plate. 2. A plurality of burners having a main flame hole at the top are arranged side by side in a burner case with a ventilation space therebetween, and a mixed gas supplied to the burner is provided in the ventilation space between the burners. In a gas combustion apparatus to which a leaner mixed gas is supplied, a secondary flame hole plate in which a number of secondary flame holes for ejecting the lean mixed gas are arranged in the longitudinal direction at the upper part of the ventilation gap between the burners. A low NOx characterized in that a rectifying member made of a honeycomb formed body is disposed under the auxiliary flame hole plate, and a ventilation resistance plate having a plurality of slits is disposed under the rectifying member. Gas combustion device. 3. A plurality of burners having a main flame hole at the top are arranged side by side in a burner case with a ventilation interval therebetween, and a mixed gas supplied to the burner is provided in the ventilation interval between the burners. In a gas combustion apparatus to which a leaner mixed gas is supplied, a secondary flame hole plate in which a number of secondary flame holes for ejecting the lean mixed gas are arranged in the longitudinal direction at the upper part of the ventilation gap between the burners. A rectifying member made of a honeycomb formed body is disposed below the auxiliary flame hole plate, and a fire transfer portion having no auxiliary flame holes is formed at an intermediate position in the longitudinal direction of the auxiliary flame hole plate. A low NOx gas combustion device characterized by being performed.