JP2011191037A - LOW NOx BURNER AND GAS WATER HEATER USING THE SAME - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low NOx burner in which a high concentration air-fuel mixture jetted from different locations of rich flame holes is made uniform, and a gas water heater using the same. <P>SOLUTION: The low NOx burner 10 includes an elongated lean flame hole 12 for upwardly jetting a low concentration air-fuel mixture introduced from a gas inlet port 34 of a first tubular flow passage 11; and rich-flame holes 14, 15 disposed surrounding the lean-flame hole 12 and upwardly jetting the high concentration air-fuel mixture introduced from a gas introduction port 39 of a second tubular flow passage 13. A vertical flow passage 40 is provided below the rich-flame holes 14, 15 for guiding the high-concentration air-fuel mixture, moving straight through the second tubular flow passage 13 and flowing rearward, to the rich flame holes 14, 15. The vertical flow passage 40 is formed wide in the front and rear and includes a plurality of rectifying mechanisms 49, 51 having a plurality of inwardly projecting portions 48, 50, disposed in the front and rear direction partially blocking the flow of the high concentration air-fuel mixture on the outlet side of the high concentration air-fuel mixture of the second tubular flow passage 13. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a low NOx burner that generates combustion gas for heating water and a gas water heater using the low NOx burner.

In order to reduce the NOx amount of the combustion gas generated at the time of combustion, an elongate pale flame mouth formed in the front-rear direction formed by a divided flame mouth group that ejects a low-concentration mixture whose fuel concentration is lower than the stoichiometric air-fuel ratio; There is a so-called low NOx burner provided with a slender concentrated flame outlet that ejects a high-concentration air-fuel mixture having a fuel concentration higher than the stoichiometric air-fuel ratio, which is disposed around the pale flame outlet. 1.
And the low NOx burner is separately provided with the inlet into which a low concentration mixture and a high concentration mixture are introduced, as described in Patent Document 1.

JP 7-42917 A

However, the rich flame outlet is formed long in the longitudinal direction of the low-NOx burner, the path from the high-concentration air-fuel mixture inlet to the rich flame outlet is short, the flow area is small, and the high-pressure from the inlet is high. Since the amount of concentration mixture introduced varies depending on the required combustion load, the amount of high-concentration mixture injection is made uniform at different locations in the front-rear direction of the rich flame outlet to balance the flame size. It is difficult.
The present invention has been made in view of such circumstances, and a low-NOx burner in which a high-concentration gas mixture ejected from different locations of the rich flame outlet is made uniform and a gas water heater using the low-NOx burner are provided. The purpose is to provide.

The low NOx burner according to the first aspect of the present invention that meets the above-mentioned object is a slender thin flame that ejects upward a low-concentration mixture having a fuel concentration lower than the stoichiometric air-fuel ratio introduced from the gas inlet of the first tubular channel. A narrow concentrated flame mouth that is disposed around the mouth and the pale flame mouth and jets a high-concentration mixture having a fuel concentration higher than the stoichiometric air-fuel ratio introduced from the gas inlet of the second tubular channel upward In the low NOx burner provided, a vertical flow path that guides the high-concentration gas mixture that goes straight through the second tubular flow path and travels backward is provided at the lower portion of the rich flame opening, The longitudinal flow path is formed wide in the front-rear direction, and a plurality of inner protrusions that partially block the flow of the high-concentration mixture are provided in the front-rear direction on the outlet side of the high-concentration mixture in the second tubular flow path There are a plurality of rectifying mechanisms arranged on the top and bottom.

In the low NOx burner according to the first invention, the vertical flow path guides a part of the high-concentration mixture to the front side of the rich flame port between the second tubular flow path and the rectifying mechanism. It is preferable that the upper part to have has an elongate inner side protrusion part inclined and arrange | positioned ahead.

In the low NOx burner according to the first aspect of the present invention, the rectifying mechanism arranged above and below is provided in the rectifying mechanism immediately below the center of each inner protrusion provided in the upper rectifying mechanism. It is preferable to arrange at a position that does not overlap the center of each of the inner protrusions in plan view.

In the low NOx burner according to the first aspect of the present invention, the vertical flow path whose center is partitioned by the side wall of the connection path connecting the first tubular flow path and the pale flame port is formed on the left and right sides of the side wall of the connection path. One of the rectifying mechanisms, which is formed by the left and right outer walls and the side walls of the connection path, provided on the upper and lower sides, is provided on the side wall of the connection path, and the other is the longitudinal flow. It is preferably provided on the outer wall of the road.

A gas water heater according to a second aspect of the present invention that meets the above object is a gas water heater that uses the low NOx burner according to the first aspect of the present invention, and is directly applied by the low NOx burner and combustion gas generated by combustion of the low NOx burner. And a secondary heat exchanger for preheating water supplied to the primary heat exchanger by the combustion gas discharged from the primary heat exchanger.

In the low NOx burner according to the first invention and the gas water heater according to the second invention, the vertical flow path provided at the lower part of the rich flame port is on the outlet side of the high concentration mixture in the second tubular flow path. Since there are a plurality of rectifying mechanisms arranged vertically in the front-rear direction that have a plurality of inner protrusions that partially block the flow of the high-concentration air-fuel mixture, the high-concentration air-fuel mixture proceeds backward through the second tubular channel Can be diffused at different locations in the front-rear direction, and the flow rate of the high-concentration mixture ejected from the rich flame outlet is made uniform, so that the height of the rich flame formed at the rich flame mouth is stabilized and uniform. Can do.

Further, in the low NOx burner according to the first invention and the gas water heater according to the second invention, the longitudinal flow path concentrates a part of the high-concentration air-fuel mixture between the second tubular flow path and the rectifying mechanism. When the upper part that guides the front side of the flame outlet has an elongated inner projecting portion that is inclined to the front side, a part of the high-concentration mixture that passes through the second tubular flow path and moves backward is concentrated. It is possible to supply stably to the front part of the flame outlet.

Then, in the low NOx burner according to the first invention and the gas water heater according to the second invention, the center of each inner protrusion provided in the upper rectifying mechanism is provided in the rectifying mechanism immediately below it. If it does not overlap with the center of each inner protrusion in plan view, the arrangement pitch of the inner protrusions in the front-rear direction can be shortened, and many locations for diffusing the high-concentration mixture are provided in the front-rear direction. The distribution can be made uniform stably.

Furthermore, in the low NOx burner according to the first invention and the gas water heater according to the second invention, one of the two rectifying mechanisms provided in the upper and lower sides is provided on the side wall of the connection path, and the other is the outer wall of the vertical flow path. The inner projecting portion can be technically easily molded and can be mass-produced.

It is a perspective view of the low NOx burner which concerns on one embodiment of this invention. It is a perspective view of a gas burner unit provided with the same low NOx burner. It is a schematic diagram of the gas water heater using the low NOx burner. It is a top view of the low NOx burner. It is a side view of the same low NOx burner which omitted an outside metal plate. It is a side view of the outer side metal plate with which the low NOx burner is provided.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
As shown in FIGS. 1 and 4 to 6, a low NOx burner 10 according to an embodiment of the present invention is a gas on the front side of a first tubular flow channel 11 arranged horizontally (along the front-rear direction). It is disposed so as to surround the pale flame port 12 and the elongated pale flame port 12 through which a low-concentration mixture having a fuel concentration lower than the stoichiometric air-fuel ratio introduced from the introduction port 34 is jetted upward, and horizontally (along the front-rear direction). A gas burner provided with elongate rich flame ports 14 and 15 for ejecting upward a high-concentration air-fuel mixture having a fuel concentration higher than the stoichiometric air-fuel ratio introduced from the gas inlet port 39 on the front side of the second tubular channel 13 disposed. is there. Details will be described below.

As shown in FIG. 2, the low NOx burner 10 is arranged in parallel inside the outer case 29 that is open at the top, and the gas burner unit 16 is configured to include a plurality of low NOx burners 10 and the outer case 29. The gas burner unit 16 burns an air-fuel mixture obtained by mixing fuel gas and air supplied from a gas pipe 18 (see FIG. 3) by the low NOx burner 10 to generate combustion gas. Here, since the low NOx burner 10 is a light and dark burner in which the amount of NOx generated is reduced, the pH of the acidic water produced by combining NOx and water vapor is improved, and the drain water can be easily treated. is there. In FIG. 2, the two low NOx burners 10 are depicted as being arranged at a distance in the outer case 29, but actually, a plurality of, for example, 15 to 20 low NOx burners 10 are illustrated. NOx burners 10 are arranged close to each other in parallel.

As shown in FIG. 3, the gas burner unit 16 supplies combustion gas to a primary heat exchanger 19 disposed at the upper part of the gas burner unit 16. The primary heat exchanger 19 heats water directly by sensible heat of the combustion gas taken from the lower part to make hot water, sends the hot water to the mixing valve 20 and discharges the combustion gas from the upper part. The mixing valve 20 mixes hot water produced by the primary heat exchanger 19 with tap water flowing through the water pipe 21 to produce hot water at a predetermined temperature, and supplies the hot water to the hot water pipe 22.
A fan 23 for supplying air into the gas burner unit 16 is fixed to the bottom of the gas burner unit 16.

A secondary heat exchanger 24 that preheats water supplied to the primary heat exchanger 19 by the combustion gas discharged from the primary heat exchanger 19 is disposed downstream of the primary heat exchanger 19. Accordingly, the gas water heater 25 having the gas burner unit 16, the primary heat exchanger 19, the secondary heat exchanger 24, and the like uses the sensible heat and latent heat of the combustion gas by the primary heat exchanger 19 and the secondary heat exchanger 24, respectively. Water can be efficiently heated. The water preheated by the secondary heat exchanger 24 is supplied from the water pipe 21.
The primary heat exchanger 19 is connected to a circulation circuit 27 through which water is circulated by the operation of a circulation pump 26 provided in the gas water heater 25. The primary heat exchanger 19 supplies hot water used for hot water supply. While heating, the water flowing through the circulation circuit 27 is heated and supplied to a bathtub or the like. In addition, the apparatus, members, etc. which comprise the gas water heater 25 including the gas burner unit 16 are fixed in the box-shaped casing 28.

As shown in FIG. 2, the outer wall portion of the outer case 29 is provided with ignition means 31 including an electrode 30 for igniting the low NOx burner 10, and is arranged at equal intervals in the left-right direction below the ignition means 31. A plurality of openings 32 are formed. The low-concentration air-fuel mixture passes through the opening 32 and is supplied to the low NOx burner 10 disposed in the outer case 29.
In addition, a plurality of openings (not shown) through which the high-concentration gas mixture supplied to the low NOx burner 10 passes are formed in the upper part of the opening 32.

As shown in FIGS. 1, 2, and 4, the low NOx burner 10 arranged in parallel in the outer case 29 is arranged in parallel with the thin flame mouth 12 elongated in front and rear and the pale flame mouth 12 interposed therebetween (that is, The elongate flame mouths 14 and 15 are provided before and after surrounding the pale flame mouth 12. Between each of the pale flame mouth 12 and the rich flame mouths 14 and 15, there is provided a blocking region 33 that does not eject the air-fuel mixture or the like, and the flame generated at the pale flame mouth 12 and the rich flame mouths 14 and 15. To prevent interference. The pale flame mouth 12 and the rich flame mouths 14 and 15 are arranged at the same height above the low NOx burner 10, and both are formed over the entire front and rear direction of the low NOx burner 10.
The low NOx burner 10 is formed with a gas inlet 34 of the first tubular channel 11 into which a low-concentration air-fuel mixture is introduced on the lower front side. A lower end portion of a connection path 35 connecting the tubular flow path 11 and the pale flame port 12 is connected. Therefore, the low-concentration gas mixture introduced from the gas introduction port 34 passes through the first tubular flow channel 11 and then is sent to the pale flame port 12 through the connection path 35. The flaming mouth 12 is formed by arranging a plurality of slit groups 37 (eight in this embodiment) in the front-rear direction, which are composed of a plurality (three in the present embodiment) of slits 36 closely arranged on the left and right. A flame (light flame) is generated using the low-concentration gas mixture ejected from each slit group 37 as fuel.

Further, the low NOx burner 10 includes a gas inlet 39 of the second tubular channel 13 into which the high-concentration air-fuel mixture is introduced above the gas inlet 34 of the first tubular channel 11. A vertical flow path 40 having the rich flame ports 14 and 15 at the upper end is provided in communication with the second tubular flow path 13, and the vertical flow path 40 is introduced from the gas introduction port 39 and is connected to the second tubular flow path. The high-concentration mixture that travels straight along the path 13 and travels backward is guided to the rich flame ports 14 and 15 at the upper end. The left and right side walls 41, 41a (see FIG. 5) that are arranged with a gap and that form the connection path 35 divide the center of the vertical channel 40 in the left-right direction, divide the vertical channel 40 into left and right, and Ventilation paths 40 a and 40 b are formed in the flow path 40. The air passages 40a and 40b are formed wide in the front-rear direction, and the rich flame ports 14 and 15 are disposed at the upper ends of the air passages 40a and 40b, respectively. The second tubular channel 13 also has a split structure in which the center in the left-right direction is vertically divided by a body fitting 42 to be described later, and the left and right parts divided into the air passages 40a and 40a, respectively. 40b.

The low NOx burner 10 includes the main body fitting 42 shown in FIG. 5 and the upper half of the main body fitting 42, as shown in FIG. Covering from the left and right, there are provided outer metal plates 43 and 44 that form the second tubular flow channel 13, the air flow channels 40 a and 40 b, and the rich flame ports 14 and 15.
The ventilation path 40a is formed by a left side wall 41 of the connection path 35 and an outer wall 45 arranged with a space on the left side (outside) of the side wall 41, and the ventilation path 40b is connected similarly to the ventilation path 40a. It is formed by a right side wall 41a of the path 35 and an outer wall 46 arranged with a space on the right side (outside) of the side wall 41a. The outer metal plates 43 and 44 are closely fixed to the main body fitting 42 by spot welding so that the high-concentration air-fuel mixture does not leak out from the air passages 40a and 40b.

In addition, as shown in FIGS. 1, 5, and 6, a plurality of (three in the present embodiment) vent passages 40 a and 40 b are provided on the outlet side of the high-concentration air-fuel mixture in the second tubular channel 13. A rectifying mechanism 49 in which the inner protrusions 48 are arranged at equal intervals in the front-rear direction (for example, 1 to 4 mm), and a plurality of (three in the present embodiment) inner protrusions disposed below the rectifying mechanism 49. It has the rectification | straightening mechanism 51 which has arrange | positioned the part 50 side by side at equal intervals (for example, 1-4 mm) in the front-back direction. The inner protrusions 48 and 50 partially block the flow of the high-concentration air-fuel mixture so that the high-concentration air-fuel mixture diffuses in the air passages 40a and 40b.
The rectifying mechanisms 49 and 51 are arranged at intervals of 1 to 3 mm in the vertical direction, and are formed at the approximate center in the front-rear direction of the low NOx burner 10. And the inner side protrusion parts 48 and 50 are the circular with a 1-5 mm radius, and protrude in the left-right direction with the protrusion height of 0.5-3 mm. In the present embodiment, the projecting heights of the inner projecting portions 48 and 50 are the same as the width in the left-right direction of the vent passages 40a and 40b.

As shown in FIG. 6, the two rear inner protrusions 50 provided on the rectifying mechanism 51 are arranged between the centers of the three inner protrusions 48 provided on the rectifying mechanism 49 in a plan view. The inner projecting portion 48 disposed in front of the rectifying mechanism 49 is disposed between the centers of the two inner projecting portions 50 on the front side of the rectifying mechanism 51 (that is, the center of each inner projecting portion 48 is It is a position that does not overlap with the center of each inner protrusion 50 in plan view).
Therefore, the high-concentration gas mixture that passes through the second tubular channel 13 and travels backward is partially changed in the traveling direction at a plurality of positions that are different in the front-rear direction and diffuses up and down, so that it is long in the front-rear direction. It can flow uniformly in different locations in the front-rear direction of the rich flame ports 14 and 15.

As shown in FIGS. 5 and 6, the inner projecting portion 48 of the rectifying mechanism 49 is formed on the side walls 41 and 41 a of the connecting path 35 by press working, and the inner projecting portion 50 of the rectifying mechanism 51 is formed by the press working. The outer walls 45 and 46 of 40a and 40b are provided. Accordingly, the inner protrusions 48 and 50 are separately provided on different work plates (metal plates), and all of the inner protrusions arranged at a slight interval are made the same work plate. Compared to forming, it is easy to mold the inner protrusion, and mass production can be achieved.

The vent passages 40a and 40b are provided with an elongated inner projecting portion 52 that is inclined with the upper portion disposed from the front between the second tubular flow passage 13 and the rectifying mechanisms 49 and 51. The elongated inner projecting portion 52 has the same projecting height as the inner projecting portions 48 and 50, and the projecting surface is an elongated circle (ellipse or ellipse) having a length in the longitudinal direction of 8 to 12 mm. Here, the distal end portions of the elongated inner projecting portion 52 and the inner projecting portion 50 abut on the side wall 41 (the same applies to the side wall 41a), and the distal end of the inner projecting portion 48 is in contact with the outer wall 45 (the same applies to the outer wall 46). , The distance between the side wall 41 and the outer wall 45 can be kept constant.
Moreover, since the elongate inner side protrusion part 52 inclines at the angle of 50-70 degrees to the front side, a part of the high concentration air-fuel | gaseous mixture introduced from the 2nd tubular flow path 13 is concentrated flame by this inclination. It can be guided to the front side of the mouths 14 and 15, and a sufficient amount of the high-concentration air-fuel mixture can be supplied to the front part of the rich flame mouths 14 and 15.

The low NOx burner 10 widely disperses the high-concentration air-fuel mixture introduced from the second tubular flow path 13 in the ventilation paths 40a and 40b by the rectifying mechanisms 49 and 51 and the elongated inner protrusion 52 described above. The high-concentration air-fuel mixture can be sent in a well-balanced manner to different locations in the front-rear direction of the rich flame ports 14 and 15. Therefore, the flames generated at the rich flame ports 14 and 15 are made uniform in size (momentum) at different locations in the front-rear direction.

Further, the outer metal plate 43 (the same applies to the outer metal plate 44) is provided with a lateral groove 54 formed in the front-rear direction, as shown in FIGS. In addition to having the effect of maintaining the strength of the outer metal plate 43, the lateral groove 54 narrows the space of the air passage 40a to moderate the rising speed of the high-concentration mixture, and is ignited at the front side of the rich flame port 14. The flame is easily transferred to the entire rich flame port 14. The circular protrusion 55 formed on the front side of the outer metal plate 43 partially reduces the flow rate of the secondary air that rises through the gaps between the plurality of low NOx burners 10 arranged in close proximity by the operation of the fan 23 (see FIG. 2). Is suppressed. That is, the circular protrusion 55 creates an environment in which the ignited flame easily moves to the low NOx burner 10 disposed adjacent to the left and right.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and all changes in conditions and the like that do not depart from the gist are within the scope of the present invention.
For example, instead of providing the elongated inner protrusions at the formation position of the elongated inner protrusions, a plurality of inner protrusions can be arranged close to each other to guide the high-concentration mixture to the front side of the rich flame outlet. .

10: Low NOx burner, 11: First tubular channel, 12: Pale flame port, 13: Second tubular channel, 14, 15: Rich flame port, 16: Gas burner unit, 18: Gas pipe, 19: Primary heat exchanger, 20: mixing valve, 21: water pipe, 22: tapping pipe, 23: fan, 24: secondary heat exchanger, 25: gas water heater, 26: circulation pump, 27: circulation circuit, 28: Casing, 29: outer case, 30: electrode, 31: ignition means, 32: opening, 33: blocking area, 34: gas inlet, 35: connecting path, 36: slit, 37: slit group, 39: gas inlet 40: Longitudinal flow path, 40a, 40b: Ventilation path, 41, 41a: Side wall, 42: Body fitting, 43, 44: Outer metal plate, 45, 46: Outer wall, 48: Inner protrusion, 49: Rectification mechanism, 50: Inner protruding part, 51: Rectification mechanism, 52: Elongated inner protruding part 54: lateral groove, 55: circular protrusion

Claims (5)

An elongated pale flame outlet for jetting a low-concentration gas mixture having a fuel concentration lower than the stoichiometric air-fuel ratio introduced from the gas inlet of the first tubular flow channel, and surrounding the pale flame orifice; In a low NOx burner provided with an elongated rich flame port for ejecting upward a high-concentration mixture having a fuel concentration higher than the stoichiometric air-fuel ratio introduced from the gas inlet of the tubular flow path of
A vertical flow path for guiding the high-concentration gas mixture that goes straight through the second tubular flow path and travels backward to the rich flame opening is provided at a lower portion of the rich flame opening. And a rectifying mechanism in which a plurality of inner protrusions that partially block the flow of the high-concentration mixture are arranged in the front-rear direction on the outlet side of the high-concentration mixture in the second tubular channel. A low NOx burner having a plurality of upper and lower sides. 2. The low NOx burner according to claim 1, wherein the vertical flow path guides a part of the high-concentration mixture to the front side of the rich flame port between the second tubular flow path and the rectifying mechanism. A low NOx burner characterized in that it has an elongated inner projecting portion whose upper part is inclined to the front side. 3. The low NOx burner according to claim 1, wherein the rectifying mechanism arranged above and below is provided in the rectifying mechanism immediately below the center of each inner protrusion provided in the upper rectifying mechanism. Further, the low NOx burner is disposed at a position that does not overlap with the center of each of the inner protrusions in plan view. The low NOx burner according to any one of claims 1 to 3, wherein the vertical flow path whose center is partitioned by a side wall of a connection path that connects the first tubular flow path and the pale flame opening is Formed by left and right outer walls arranged on the left and right of the side wall of the connection path and the side wall of the connection path,
One of the two rectifying mechanisms provided on the upper and lower sides is provided on the side wall of the connection path, and the other is provided on the outer wall of the vertical flow path. A gas water heater using the low NOx burner according to any one of claims 1 to 4, wherein the primary heat heats water directly by the low NOx burner and combustion gas generated by combustion of the low NOx burner. A gas water heater comprising: an exchanger; and a secondary heat exchanger that preheats water supplied to the primary heat exchanger by the combustion gas discharged from the primary heat exchanger.

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