JP2622475B2 - 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 On both sides of a main crater of a flat main burner, there is provided a sleeve fire burner forming a slit-shaped sleeve crater sandwiching the main crater. There has been proposed a low-nitrogen oxide burner for supplying a fuel-air mixture (hereinafter, referred to as an air-rich mixture) and another fuel-air mixture (including only fuel; hereinafter, referred to as a gas-rich mixture).

Japanese Patent Laid-Open Publication No. Hei 3-263503 discloses that the excess air ratio of some burners is set to be larger than 1.4, the excess air ratio of the other burners is set to be smaller than 0.8, and the whole is fixed. 120 pp when burned at an air-fuel ratio of
40 to 60p of nitrogen oxides (NOX) discharged about m
A low nitrogen oxide (low NOx) burner that can be reduced to pm is disclosed.

However, in this burner, the amount of air mixture is small on the gas-rich mixture side and the amount of mixture is small, so that the flow rate of the mixture is small. As a result, if this type of low-nitrogen oxide burner is used as a heating source such as a water heater that needs to greatly change the calorific value in accordance with tapping conditions, the burner on the gas-rich mixture side mixes during low load combustion. The flow velocity of the air becomes smaller than the flame propagation speed, and a flashback in which the flame is sucked into the burner from the crater easily occurs.

[0005]

If a flashback occurs and combustion continues in a state in which the flame is sucked into the burner, overheating of parts constituting the burner, adhesion of soot to the inside of the burner, misfiring, noise, etc. Troubles such as occurrence occur. An object of the present invention is to provide a gas-rich mixture-side burner flame that can be held near a crater even during low-load combustion with a reduced calorific value, drawn into the burner, and even provided with fuel gas and primary air inlets. The purpose of the present invention is to provide a low-nitrogen oxide burner that can prevent the flashback from reaching.

[0006]

A low-nitrogen oxide burner according to the present invention comprises a second burner forming a crater beside a crater of a first burner, wherein the second burner is connected to the first burner. Independently, in a burner having a suction port for sucking a fuel gas, one of a first burner and a second burner is supplied with an excess fuel-fuel mixture equal to or higher than an ignition limit, and one of the other burners has an excess air. In addition to supplying the air-fuel mixture, a communication passage is formed in the vicinity of the crater of the burner on the side of the fuel-rich mixture to guide the air-fuel mixture into the burner of the fuel-fuel mixture.

[0007]

According to the present invention, a gas-rich mixture that is higher than the ignition limit is supplied to the gas-rich mixture burner.
A communication passage is provided near the crater of the burner, and the mixture of the air-rich mixture side burner is supplied to the gas-rich mixture side burner through the communication passage to dilute the mixture to the combustible air-fuel ratio.
Even when the flow rate of the air-fuel mixture in the gas-rich air-fuel mixture burner starts to decrease during low load combustion, the flame is sucked only up to the communication passage where the combustible air-fuel mixture exists. For this reason, troubles such as overheating of components constituting the burner, adhesion of soot to the inside of the burner, misfire, generation of noise, and the like 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 flat main burner having an elongated main crater 11 formed of slits arranged side by side at the upper end and an inlet 12 for air-fuel mixture provided on the side as shown in FIG. 1 and FIG. 1
(First burner).

[0009] The main burner 1 has (b) of FIGS.
As shown in the figure, flat slit-shaped sleeve craters 21 and 21 are formed on both sides of the main crater 11, and a sleeve fire burner 2 (second burner) provided with a common suction port 22 on the side is provided. . In the vicinity of the sleeve craters 21, 21, there is formed a communication passage 3 composed of a row of slits for communicating the flow path in the main burner 1 and the sleeve craters 21, 21 of the sleeve fire burner 2.

FIG. 3 shows a water heater. 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. For example, the main burner 1 burns twice as much as the sleeve fire burner 2,
A large amount of fuel gas ejected from the nozzle 42 entrains a large amount of primary air and flows from the suction port 12 into the main burner 1 at a large flow rate. As a result, the internal pressure of the main burner 1 becomes higher than the internal pressure of the sleeve fire burner 2, and as shown in FIG.
Combustion at 1.

A small amount of fuel gas injected from the nozzle 52 entrains a small amount of primary air and flows from the common suction port 22 to the sleeve fire burner 2 at a small flow rate, becomes lower in pressure than the internal pressure of the main burner 1, and is dispersed on both sides. Then, it burns at the sleeve craters 21, 21. The maintenance of low pressure in the vicinity of the sleeve crater 21 of the sleeve crater 2 can also be achieved by setting the area of the sleeve crater 21 larger than the area of the main crater 1.

The excess air ratio as a combustion condition of the main burner 1 is set to a lean air-fuel ratio of, for example, 1.4, and the excess air ratio of the sleeve fire burner 2 is a fuel-rich air-fuel ratio outside the flammable limit. (For example, when the fuel gas is methane, the excess air ratio is set to 0.6 or less). Since the sleeve fire burner 2 is out of the flammable limit, continuous ignition combustion cannot be performed.
Since there is a difference in the relative internal pressure between the main burner 1 and the sleeve fire burner 2, the air-rich mixture in the main burner 1 is supplied from the communication passages 3, 3. Therefore, the sleeve fire burner 2
Above the communication passages 3, 3, the air-fuel ratio is such that ignition and combustion are possible. Thereby, the flame of the sleeve fire burner 2 is
2 can be prevented from backfire.

In accordance with the setting of the hot water supply temperature of the water heater, for example, 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 rates of the air-fuel mixture in the main burner 1 and the sleeve burner 2 decrease as shown in FIG. In this case, the flow rate of the gas-rich mixture in the sleeve fire burner 2 on the side of the sleeve crater 21 from the communication passage 3 may be lower than the flame propagation speed.

At this time, the flame F is a slit-shaped sleeve crater 21.
From the inside of the sleeve fire burner 2, but since the air-fuel ratio at the back of the communication passages 3 and 3 is not ignitable, the flame is prevented from propagating to the inside of the sleeve fire burner 2. When the combustion load increases and the flow rate of the air-fuel mixture in the sleeve fire burner 2 increases,
The flame F returns to the sleeve crater 21. Since the opening areas of the communication passages 3 and 3 are set to be as small as 0.5 mm or less in width and 3 to 4 mm in length, the flame F is prevented from entering the main burner 1 from the communication passages 3 and 3. You.

In the above embodiment, the sleeve burner 2 is a burner of a gas-rich mixture, and the main burner 1 is a low nitrogen oxide burner 100 of an air-rich mixture. However, even if the air-fuel ratio of the mixture is reversed. Alternatively, a fuel gas containing no primary air may be supplied to the burner on the gas-rich mixture side. Further, the communication path 3 may be constituted by a row of holes other than the slit, and the structure of the burner may be other than this. Furthermore, the structure of the low-nitride oxide burner may be a structure in which one main burner 1 is sandwiched between two sleeve burners each having an independent suction port.

[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 cross-sectional view of a low nitrogen oxide burner.

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

FIG. 4 is a sectional view of a low nitrogen oxide burner.

[Explanation of symbols]

 Reference Signs List 1 main burner (first burner) 2 sleeve fire burner (second burner) 3 communication passage 4 fuel gas supply pipe of main burner 5 fuel gas supply pipe of sleeve fire burner 11 main crater (crater) 12 suction port 21 sleeve crater ( Tinder) 22 Common inlet 100 Low nitrogen oxide burner

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Kazuo Yagi 2-26, Fukuzumi-cho, Nakagawa-ku, Nagoya-shi Inside Linhai Corporation (56) References JP-A-4-151412 (JP, A) JP-A-3-3 263503 (JP, A) Japanese Utility Model 4-63914 (JP, U) Japanese Utility Model 2-109132 (JP, U) Japanese Utility Model 2-115627 (JP, U)

Claims (1)

(57) [Claims] 1. A burner having a second burner forming a crater beside a crater of the first burner, the second burner having a suction port for sucking a fuel gas independently of the first burner. in, in one of the first burner and the second burner, supplying fuel excess mixture above ignition limit supplies a mixture of air excess in the other one, an excess fuel air mixture side bar
Low nitrogen oxides burners, characterized in that in proximity to the crater of over Na and the excess air mixture to form a communication passage leading to the burner of the excess fuel mixture.