JP2622477B2 - Low nitrogen oxide burner - 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 nitrogen oxide burner used for a heating source such as a gas water heater.

[0002]

2. Description of the Related Art A sleeve fire burner forming a sleeve crater sandwiching the main crater is provided on the side of the main crater of the flat main burner, and one of the main burner and the sleeve fire burner is provided with fuel-rich fuel air. Supply a mixture (hereinafter referred to as a gas-rich mixture),
A low-nitrogen oxide burner for supplying an air-rich fuel-air mixture (hereinafter referred to as an air-rich mixture) to one of the other has been proposed.

[0003] For example, when the excess air ratio of the main burner is set to be larger than 1.2 and the excess air ratio of the sleeve fire burner is set to be smaller than 0.8, the low nitrogen oxide burner as a whole has a constant air-fuel ratio. It is known that the amount of nitrogen oxides (NOx) can be reduced to 40 to 60 ppm as compared with the case where about 120 ppm of nitrogen oxides (NOX) are emitted when the fuel is burned at a temperature of about 0.5 ppm.

[0004] In a water heater or the like, it is necessary to greatly change the calorific value according to the tapping conditions. In a low-nitrogen oxide burner that burns a gas-rich mixture with a sode fire burner, the flow rate of the mixture in the sode fire burner is small, and during low load combustion,
The flow rate of the mixture may be lower than the flame propagation speed.

[0005] In addition, since the sleeve crater burner is usually formed along the outer periphery of the burner and is elongated, variations in dimensions at the time of manufacture are caused.
Due to deformation over time, the gap between the sleeve craters is partially increased, and the combustion is difficult to be uniform. As a result, uniform combustion flame is difficult to be generated along the entire width of the sleeve crater, and the flame tends to be unstable, such as a flashback where the flame is partially sucked into the sleeve fire burner from the sleeve crater.

[0006]

When flashback occurs in the sleeve fire burner and combustion continues in a state where the flame is sucked into the inside, overheating of parts constituting the burner, adhesion of soot to the inside of the burner, Troubles such as misfiring and noise may occur. An object of the present invention is to stabilize combustion in a low-nitrogen oxide burner that has a sleeve crater on both sides of a flat main crater and supplies a gas-rich mixture to the main crater and an air-rich mixture to the sleeve crater. An object of the present invention is to provide a low-nitrogen oxide burner capable of preventing a portion where a flame does not partially occur at the time of low-load combustion with a reduced calorific value and preventing a flashback from occurring in a flame of a sleeve fire burner.

[0007]

According to a first aspect of the present invention, there is provided a main burner having a flat main crater, and a sleeve fire burner forming a sleeve crater on both sides of the main crater. In a low-nitrogen oxide burner that burns an excess air-fuel mixture and burns an excess fuel-air mixture with the sleeve fire burner, the sleeve fire burner forms a window located above the main crater. A plurality of punches are arranged in a row, small holes having the sleeve crater as a plurality of flame holes are arranged on both sides of the main crater, and a sheet metal having an outer wall orthogonally bent outside the sleeve craters. A cover is formed by covering the main burner with a flow path of an excess fuel-air mixture between the cover and the outer surface of the main burner. The invention described in claim 2 is characterized in that the plurality of punches and the plurality of small holes are formed by a plurality of continuous punches in which the punches and the small holes communicate. According to a third aspect of the present invention, there is provided a main burner having a flat main crater, and a sleeve fire burner forming a sleeve crater on both sides of the main crater, and the main burner burns an excess air-fuel mixture. A low-nitrogen oxide burner that burns an excess fuel-air mixture with the sleeve fire burner;
The sleeve burner, the main crater and the sleeve crater extend in the transverse direction of the main burner, and a number of slit-shaped punches are arranged in parallel in the longitudinal direction, and are orthogonally bent outside the punched row. A sheet metal cover having an outer side wall is formed so as to cover the main burner with a flow path of a fuel-air mixture in excess of fuel between the cover and the outer surface of the main burner.

[0008]

According to the first to third aspects of the present invention, small holes having a large number of flame holes in the sleeve crater are arranged in the sleeve fire burner of the gas-rich combustion in which non-uniform combustion at the crater and flashback are likely to occur. The opening area of the flame outlet is reduced. For this reason, the area of the sleeve crater is reduced, the speed of the jet jet spouting from the open portion is increased, and occurrence of flashback can be prevented. As a result, overheating of the components that make up the burner,
Troubles such as adhesion of soot inside the burner, misfire, and noise generation can be eliminated. In addition, the cover can be molded simultaneously with the sleeve fire burner, thereby reducing manufacturing costs. In particular, the sleeve fire burner is formed along both sides of the main burner and is elongated, so that the uniformity of combustion occurs due to dimensional variations during assembly, temporal deformation due to heat, etc., the gap in the sleeve crater partially increases, etc. According to the present invention, the window of the main crater and the sleeve craters on both sides thereof are formed by punching an integrated sheet metal. As a result, distortion of the sleeve crater due to variations in dimensions at the time of assembling, temporal deformation due to heat, and the like can be effectively prevented, and a uniform combustion flame can be generated over the entire width over a long period of time. Accordingly, it is possible to redundantly prevent occurrence of a trouble such as occurrence of flashback in which the flame is partially sucked into the sleeve fire burner from the sleeve crater, and stable combustion can be constantly obtained for a long period of time.

[0009]

FIG. 1 shows a combustion section of a water heater in which a low-nitrogen oxide burner 100 according to the present invention is fixed by a frame (not shown) and arranged at predetermined intervals. Low nitrogen oxide burner 1
Reference numeral 00 denotes a flat main burner 1 having an elongated main crater 11 formed of a group of slits arranged side by side at an upper end, and a suction port 12 for an air-fuel mixture provided on a side portion, and flat main craters on both sides of the main crater 11. And a sleeve fire burner 2 having a common inlet 22 for air-fuel mixture on the side.

As shown in FIGS. 1 and 4, the main crater 11 and both sleeve craters 21 and 21 are provided with a cover 4 with a window 3 formed by extending the outer edge of the sleeve fire burner 2 in a bridging manner. ing. The window 3 has a plurality of rectangular windows 31 opening above a subset of four slits constituting the main crater 11, and each of the sleeve craters 21 and 21 is divided into a number of flame craters. The craters 21 include slit-shaped flame rows 32 partially closing the craters 21.

The main burner 1 punches out a group of slits arranged in parallel at the center position of the sheet metal to be the main crater 11 and forms a bulging portion 1A symmetrically on both sides with an orthogonal plane including the center line as a plane of symmetry. As shown in FIGS. 2 (a) and 3 (a) and 3 (b), the center line excluding the bulging portion 1A is bent into a U-shape with the center line as a reference (upper edge in the drawing). The flat plate portions 1B are overlapped and spot-welded. Thereby, the main crater 11 composed of a group of slits formed in parallel is formed at the upper end, and a suction port 12 for fuel gas and primary air is provided at one end by the bulging portion 1A of the sheet metal,
A flow path 13 is formed in the inside from the inlet 12 to the main crater 11. The entrance 14 is located above the flow path 13.
A channel 15 having an opening 16 and an outlet 16 is formed similarly to the channel 13, and the outlet 16 is a cutout opening. Further, it is desirable that the edge of the flat plate portion 1B be bent in a U-shape in order to prevent gas leakage.

The sleeve fire burner 2 is formed as follows.
A large number of punched rectangular windows 31 corresponding to the main crater 11 are continuously provided, leaving the cover 4 which is a bridge portion at the center position of the sheet metal. At the same time, slit-shaped flame port arrays 32, 32 are provided in parallel on both sides of the rectangular window 31 (see FIGS. 1 and 4). Next, the bulging portion 2A is formed symmetrically on both sides with the center line as a plane of symmetry. Further, it is bent into a U-shape with the center line of the portion excluding the bulging portion 2A as a reference (upper edge in the drawing), and FIG. 2 (b) and FIG.
As shown in (b), the cover 20 is formed.

Next, FIGS. 1 and 2B and FIG.
As shown in FIGS. 1A and 1B, the cover 20 is placed on the main burner 1, and the flat plate portion 2B of the cover 20 is placed on the main burner 1.
And is spot-welded. Like the main burner 1, the edge of the flat plate portion 2B is preferably overlapped and bent into a U-shape to prevent gas leakage.

The bulging portion 2A is provided at the main crater 1 of the main burner 1.
1, the inlet 12 and the channels 13 and 15 are wrapped, and the sleeve craters 21 and 21, the common inlet 22 for fuel gas and primary air, and the common inlet 22 to the sleeve crater 2
A flow path 23 connected to 1 and 21 is formed. The slit-shaped flame rows 32, 32 partition the sleeve craters 21, 21 into a number of flame flares and partially block the sleeve craters 21, 21 to reduce the opening area. In this flame port row 32, the width of each slit is set to 0.5 mm or less and the length is set to 3 to 4 mm.
The flame-extinguishing effect of the solid wall prevents the flame from propagating inside.

FIG. 5 shows a water heater, in which fuel gas supply pipes 5 and 6 correspond to 12 rows of inlets of the main burner 1 and 22 rows of common inlets of the sleeve fire burner 2 of the low nitride oxide burners 100 group. Are juxtaposed. The supply pipes 5 and 6 are provided with nozzles 51 and 61, respectively, and are provided with proportional valves 52 and 62 for controlling the flow rate of the fuel gas.
The fuel gas ejected from the nozzle 51 entrains the primary air, flows from the inlet 12 to the flow path 13, and burns at the main crater 11 as shown in FIG. 4. The fuel gas injected from the nozzle 61 entrains the primary air, and flows from the common suction port 22 to the flow path 23.
And burns in the row of flames 32.

The excess air ratio as a combustion condition of the main burner 1 is set so as to have a lean air-fuel ratio of, for example, 1.4. Set to fuel ratio. As a result, when the whole is burned at the stoichiometric air-fuel ratio with an excess air ratio of 1, 120 pp
m NOx emissions can be reduced to 40-60 ppm.

In accordance with the setting of the hot water supply temperature of the water heater, the combustion amount is increased or decreased from a maximum of 30,000 kcal to a minimum of 3,000 kcal. By reducing the combustion load, the main burner 1
And the flow velocity of the mixture in the sleeve fire burner 2 decreases.
In this case, the flow rate of the air-fuel mixture at the main crater 11 is set so as to be maintained at the flame propagation speed or more even at the time of the minimum load, but the flow velocity of the air-fuel mixture at the sleeve crater 21 becomes lower than the flame propagation speed. There is. However, in the present invention, since the sleeve crater 21 is narrowed by the cover 4 so that the degree of opening is not reversed, the flow velocity is maintained at the flame propagation speed or more, and the flame enters the inside of the burner from the slit-shaped sleeve crater 21. The propagation of the flame to the back is prevented.

FIGS. 6A and 6B show a second embodiment. In this embodiment, the sleeve crater 2 of the sleeve fire burner 2 is replaced by a number of bridges 7 instead of the cover 4 with the window 3 of the first embodiment.
1, 21 are divided into a large number of flame port rows 32, and the sleeve craters 21, 21 are partially closed. It is desirable that the number and width of the bridges 7 be set so that each sleeve crater 21 is closed so as not to flash back, and at least five flame port rows 32 are dispersed and formed at equal intervals.

FIGS. 7A and 7B show a third embodiment. In this embodiment, the window 3 in the cover 4 with the window 3 of the first embodiment is provided with a wide slit 8 including both sleeve craters 21, 21 at a position corresponding to the slit constituting the main crater 11 of the main burner 1. Is formed. In these second and third embodiments, the same effects as those in the first embodiment can be obtained. The structure of the low-nitrogen oxide burner 100 may be such that the flow path 15 is connected to the main crater 11 and the flow path 13 is connected to the sleeve crater 21. (Ie, channels 15 and 13
May be reversed. In addition, the flow path having the outlet 16 may have a cut-off portion.

[Brief description of the drawings]

FIG. 1 is a perspective view of a combustion section of a gas water heater using a low nitrogen oxide burner of the present invention.

FIG. 2 is a side view of a main burner and a cover.

FIG. 3 is a sectional view of a main burner and a cover.

FIG. 4 is a sectional view and a plan view of the low nitrogen oxide burner of the first embodiment.

FIG. 5 is a schematic view of a gas water heater equipped with a low nitrogen oxide burner.

FIG. 6 is a sectional view and a plan view of a low-nitrogen oxide burner of a second embodiment.

FIG. 7 is a sectional view and a plan view of a low-nitrogen oxide burner of a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main burner 2 Sleeve fire burner 3 Window 4 Cover 5 Fuel gas supply pipe of main burner 6 Fuel gas supply pipe of sleeve fire burner 11 Main crater 20 Cover 21 Sleeve crater 32 Flame array (flame crater) 100 Low nitride oxide burner

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Kazuo Yagi, 2-26, Fukuzumicho, Nakagawa-ku, Nagoya-shi Linnai Co., Ltd. (56) References JP-A-4-151412 (JP, A) JP-A-4-151 63914 (JP, U) JP 473713 (JP, U)

Claims (3)

(57) [Claims] A main burner having a flat main crater;
With sleeve fire burners forming sleeve craters on both sides of the main crater,
Combustion of excess air-fuel mixture in the main burner
And a fuel-air mixture in excess of fuel is burned by the sleeve fire burner.
In a low nitrogen oxide burner to be burned , the sleeve fire burner forms a window located above the main crater.
A plurality of punches are arranged in a row,
Small holes having a plurality of flame holes as the crater are arranged in a row.
Has orthogonally bent outer walls outside the crater
Insert the sheet metal cover between the outside of the main burner and the fuel
The main burner is covered with a flow path for excess fuel-air mixture.
A low-nitrogen oxide burner characterized by being formed . 2. The method according to claim 1, wherein the plurality of punches are provided.
The plurality of small holes, the punching and the small holes communicate with each other
A low nitrogen oxide burner characterized by being formed by a plurality of continuous punches . 3. A main burner having a flat main crater, the
With sleeve fire burners forming sleeve craters on both sides of the main crater ,
Said main burner air excess fuel air mixture is burned in, at low nitrogen oxides burners for burning excess fuel air mixture fuel in the sleeve fire burner, the sleeve fire burner, the main crater and sleeves crater, the Primary burner
Punching in multiple slits in the longitudinal direction
Are arranged in parallel and are orthogonal to the outside of the punching row.
The cover made of sheet metal having an outer wall
Excess fuel-air mixture flow to and from the burner outer surface
A low-nitrogen oxide burner formed so as to cover the main burner with a passage .