JP2622476B2 - 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 which is assembled so as to be arranged in a row with a certain gap therebetween and is used for a heating source such as a gas water heater.

[0002]

2. Description of the Related Art A sleeve-fire burner forming a slit-shaped sleeve crater is provided on the side of a main crater of a flat main burner, and a fuel-air mixture (excess air in the main burner and excess fuel in the sleeve-fire burner) is provided. A low-nitrogen oxide burner for supplying an air-fuel mixture has been proposed.

JP-A-3-263505 discloses that the excess air ratio of the main burner is set to be larger than 1.4, the excess air ratio of the sleeve fire burner is set to be smaller than 0.8, and the entire air-fuel ratio is kept constant. Discloses a low nitrogen oxide (low NOx) burner which can reduce nitrogen oxides (NOx) emitted at about 120 ppm to 40 to 60 ppm when burned.

However, if a low nitrogen oxide burner of this type is used as a heating source such as a water heater that requires a large change in the amount of heat generated in accordance with the tapping conditions, the sleeve crater becomes stable during high load combustion due to excessive fuel. In a sleeve fire burner in which the flow rate of the air-fuel mixture is set low to form a flame, the flow rate of the air-fuel mixture becomes lower than the flame propagation speed during low load combustion, and flashback occurs when the flame is sucked into the burner from the sleeve crater. Easy to occur.

[0005]

If flashback occurs and combustion continues in a state in which a flame is sucked into the sleeve fire burner or in a state close to gas ejected from the nozzle, the burner overheats and the burner burns into the burner. Troubles such as adhesion of soot, misfire, generation of noise, etc. occur. It is an object of the present invention to provide a method for holding a flame near a sleeve crater and drawing into the inside of a sleeve fire burner even when flashback occurs in the flame of an excess fuel side burner during low load combustion with a reduced calorific value. It is an object of the present invention to provide a low-nitrogen oxide burner which can prevent the mixture from reaching the nozzle provided at the inlet of the mixture.

[0006]

According to the present invention, a slit-shaped sleeve crater sandwiching the main crater is formed on both sides of the main crater of the flat main burner, and independently of the main burner.
It has a common suction port for supplying a mixture of fuel gas and primary air to both sleeve craters, supplies a mixture of excess air to the main burner, and supplies a mixture of excess fuel to the sleeve burner. A nitrogen oxide burner, characterized in that a throttle portion for preventing backfire is formed in the sleeve burner on the upstream side at a small distance from the sleeve crater. Note that the constricted portion is 0.5
It is formed by a slit having a width of not more than mm or a row of holes having a diameter of not more than 1.0 mm.

[0007]

According to the present invention, a two-sleeve crater having a common suction port is provided to supply an air-fuel mixture independent of the main burner to the two-sleeve fire burner. For this reason, an air-fuel mixture having an optimum air-fuel ratio can be supplied to the two-sleeve fire burner, and the air-fuel ratio of the air-fuel mixture at the two-sleeve crater becomes constant. And, by the throttle portion for preventing the suction of the flames F, F of both sleeve fire burners, the suction of the sleeve flames F, F can be surely prevented. In other words, even if the flow rate of the air-fuel mixture from both sleeve craters decreases during low load combustion and flashback begins to occur, the flame stops at both throttle portions simultaneously. Therefore, in the flat burner with the common inlet and double-sided fire burner, troubles such as overheating of the burner, adhesion of soot to the inside of the burner, misfire, generation of noise, etc. can be prevented, and safety is high.

[0008]

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 main burner 1 having a flat main crater 11 and a sleeve fire burner 2 forming slit-shaped sleeve craters 21 on both sides of the main crater 11.

The main burner 1 is made of sheet metal. As shown in FIG. 1 and FIG. 2 (a), the main burner 1 is provided with the elongated main crater 11 composed of a group of slit flame ports arranged side by side at the upper end, and an air-fuel mixture on the side. Are provided.

The sleeve fire burner 2 is made of sheet metal. As shown in FIG. 1, the sleeve fire craters 21 are formed in a flat slit shape across the entire width of the main fire crater 11 with the main fire crater 11 interposed therebetween. As shown in (b), one common suction port 22 is provided on the side. In the vicinity of the sleeve craters 21, 21, a slit-shaped throttle portion 3 is formed. In this embodiment, as shown in FIG. 4, the squeezed portion 3 is welded to either the outer wall surface 1A of the main burner 1 or the inner wall surface 2A of the sleeve fire burner 2, and is provided by a metal plate 32 provided with a slit row 31. Is formed.

FIG. 3 shows a water heater, in which fuel gas supply pipes 4 and 5 correspond to the inlet 12 of the main burner 1 of the low nitrogen oxide burner 100 and the common inlet 22 of the sleeve fire burner 2.
Are juxtaposed. The supply pipes 4 and 5 are provided with proportional valves 41 and 51 for controlling the flow rate of the fuel gas, and the nozzles 42 and 52 are arranged in rows. The fuel gas ejected from the nozzle 42 entrains primary air and becomes an air-excess air-fuel mixture having a large flow velocity, and becomes a main burner 1 through the suction port 12.
And burns lean at the main crater 11 as shown in FIG.

The fuel gas injected from the nozzle 52 entrains the primary air and becomes a fuel-rich mixture having a small flow velocity, flows into the sleeve burner 2 from the common suction port 22, and is dispersed to both sides of the main burner 1. Excessive fuel combustion occurs at the craters 21, 21. In the upstream narrowed portion 3 having a small gap from the sleeve craters 21, 21, the flow rate of the air-fuel mixture temporarily increases, but in the sleeve craters 21, 21 downstream by the gap between the sleeves. However, the flow rate of the air-fuel mixture is decreasing, and the flame formed above the sleeve craters 21 is a gentle and stable flame.

As in this embodiment, since the sleeve burner 2 is provided with the common suction port 22, it is not influenced by the manufacturing and assembling variation and the variation in the opening adjustment of the suction port by a damper (not shown). Sleeve crater 21, 21
There is an advantage that the air-fuel ratio of the air-fuel mixture supplied to the fuel cell can be made constant.

The combustion condition of the main burner 1 is set so that the excess air ratio is 1.4, for example, and the excess air ratio in the sleeve fire burner 2 is set to 0.8. You. As a result, the main burner 1 performs lean combustion with excess combustion air, the sleeve burner 2 performs excessive fuel combustion with insufficient combustion air, and the unburned gas reacts with excess air of the lean combustion flame to completely burn. . Thereby, 120 pp generated when the whole is burned at a substantially constant air-fuel ratio is generated.
m NOx emissions can be reduced to 40-60 ppm.

According to the setting of the hot water temperature of the water heater, the combustion amount is increased or decreased from 30,000 kcal at the maximum to 3,000 kcal at the minimum. Due to the reduction of the combustion load, the flow rate of the air-fuel mixture in the main burner 1 and the sleeve fire burner 2 decreases as shown in FIG. At this time, the sleeve crater 21 of the sleeve fire burner 2
In some cases, the flow rate of the air-fuel mixture ejected from the nozzle 21 becomes lower than the flame propagation speed, and flashback begins to occur.

In this case, according to the present invention, FIG.
As shown in (b), the flame F has a slit-shaped sleeve crater 21.
However, the flow of the air-fuel mixture is kept high in the narrowed portions 3 and the flame of the narrowed portion 3 has a flame-extinguishing effect. That is prevented. When the combustion load increases and the flow rate of the air-fuel mixture increases, the flames F can return to the sleeve crater 21 because the throttle portions 3 are located near the sleeve craters 21. The cross section taken along line II of FIG. 4A is FIG. 4B.

The throttle unit 3 is 0.5 mm below the flashback limit.
It is desirable to have the following slit width. In addition, the aperture section 3 may be a hole row having a diameter of 1.0 mm or less other than the slit row. Further, as shown in FIG. 5, the bulging portions 1B, 2B are opposed to the wall surface of the main burner 1 and the wall surface of the sleeve fire burner 2.
By providing B, a slit having a width of 0.5 mm or less can be formed.

[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 sleeve fire burner.

FIG. 3 is a schematic view of a gas water heater equipped with a low nitrogen oxide burner.

FIG. 4 is a plan view and a sectional view of a main part of a low nitrogen oxide burner.

FIG. 5 is a cross-sectional view of a main part of a low nitrogen oxide burner according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main burner 2 Sleeve fire burner 3 Throttle part 4 Fuel gas supply pipe of main burner 5 Fuel gas supply pipe of sleeve fire burner 11 Main crater 21 Sleeve crater 22 Common suction port 100 Low nitride oxide burner

Continuation of the front page (72) Inventor Hideaki Ishikawa 2-26 Fukuzumi-cho, Nakagawa-ku, Nagoya-shi Inside Linhai Corporation (56) References JP-A-4-151412 (JP, A) JP-A-4-63914 (JP) , U) Japanese Utility Model Hei 2-109132 (JP, U) Japanese Utility Model Hei 3-104611 (JP, U) Japanese Utility Model Hei 4-73714 (JP, U)

Claims (2)

(57) [Claims] 1. The main crater of a flat main burner is provided on both sides of the main crater .
While forming a slit-shaped sleeve crater sandwiching the crater ,
Independently of the main burner, both sleeve craters have a common inlet for supplying a mixture of fuel gas and primary air, the main burner is supplied with an excess air-fuel mixture, and the sleeve burner is supplied with fuel. meet our low nitrogen oxide burner for supplying a mixture of excess
A low-nitrogen oxide burner characterized in that a throttle portion for preventing flashback is formed on the upstream side of the sleeve fire burner at a small distance from the sleeve crater. 2. The apparatus according to claim 1, wherein the throttle section has a diameter of 0.1 mm.
5mm or less slit or 1.0mm or less diameter
A low-nitrogen oxide burner formed of a row of holes .