JPH04121510A - Low nox burner - Google Patents

Abstract

PURPOSE:To reduce the generation of NOx in exhaust gas and to prevent the occurrence of flashback of flame to a fuel-air mixture passage outlet by a method wherein a flashback preventing plate is located in a combustion air passage and on the upper stream side of the fuel-air mixture passage, and a rim part is located between a burner port and the combustion air passage. CONSTITUTION:A rim part 9 having a flame stabilizing distance of 2-7mm is located between the slit of a burner port 1 and a combustion air passage outlet 8, and a flashback preventing plate 11 inclined from the central part of a combustion air passage 10 toward a fuel-air mixture passage 6 is mounted facing both sides of a burner body 2. This constitution induces a part of air in the combustion air passage 10 to the outlet of the passage 6 by means of the flashback preventing plate 11 and vertically crosses fuel-air mixture injected through the passage 6, whereby flame is blown off and prevented from flashback to the passage 6. Further, by locating the rim part 9, the burner port part 1 generates a recirculation region for fuel-air mixture injected through the passage outlet 8. Flame is stabilized and fuel-air mixture having low oxygen concentration is fed through the outlet 8 to flame formed at the burner port 1 to reduce the generation of thermal NCx.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a low NOx combustor.

BACKGROUND OF THE INVENTION There is an increasing demand for a low NOx combustor that reduces NOx in exhaust gas, prevents flame flashback, and improves burner durability.

Conventionally, this type of low NOx combustor has a first air-fuel mixture chamber 3 provided in a burner body 2 having a first flame port 1, and the first air-fuel mixture chamber 3, as shown in FIG. A second air-fuel mixture chamber 5 having a second flame port 4 provided on both sides of the burner body 2 is provided in the burner body 2 to communicate the first air-fuel mixture chamber 3 and the second air-fuel mixture chamber 5. The second air-fuel mixture chamber 5 is provided with an air-air mixture road 6 and an air intake lower that sets the primary air ratio of the second air-fuel mixture chamber 5 . In such a configuration, combustion is slowed down by supplying the unburned air-fuel mixture with a low oxygen concentration ejected from the second flame port 4 to the flame formed on the first flame port 1. , lowering the flame temperature and reducing the generation of thermal NOx.

Problems to be Solved by the Invention Although the configuration of such a conventional low NOx combustor is satisfactory in terms of the effect of reducing NOx, as the combustion amount is reduced, the primary There was a problem in that the air ratio increased and the flame backfired from the first flame port to the second flame port to the outlet of the mixture passage, causing the burner body to become abnormally heated.

The present invention solves the above-mentioned problems, and aims to reduce NO in exhaust gas.
It is an object of the present invention to provide a low NOx combustor that can reduce X and prevent backfire of the flame toward the exit of the mixture passage, and improve the durability of the burner.

Means for Solving the Problems In order to achieve the above object, the present invention provides a large number of burners arranged in parallel, a combustion air passage provided between the burners, and a large number of flame ports provided in the burners. a mixture chamber provided in the burner on the downstream side of the combustion port, a mixture passage communicating with the combustion air passage on the side of the mixture chamber; A flashback prevention plate inclined from the center of the combustion air passage toward the mixture passage within the combustion air passage and upstream of the mixture passage, and a rim between the flame port and the combustion air passage. It has a structure in which a section is provided.

Effect of the Invention With the above-described configuration, the present invention allows a part of the air in the combustion air passage to be guided in its course direction to the outlet of the mixture passage by the flashback prevention plate, and is turned into a high-velocity air stream and jetted out from the mixture passage. intersects perpendicularly to the air-fuel mixture. In addition, the rim part prevents the flow of a thin mixture of air-fuel mixture and combustion air ejected from the mixture passage from coming into direct contact with the flame formed on the flame nozzle, and also By supplying a thin mixture of the air-fuel mixture ejected from the air-fuel mixture passage and combustion air to the flame, combustion is slowed down.
It lowers the flame temperature.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2. Note that the same parts as in the conventional example are given the same numbers and detailed explanations will be omitted.

As shown in the figure, a flame port 1 with a large number of slits is provided on the upper surface of the burner body 2, and a rim with a flame holding distance of 2 m to 7 cm is provided between the slits and the combustion air passage outlet 8. Section 9 is provided. Mixture roads 6 are provided on both sides of the burner body 2 at optimal intervals in the longitudinal direction.
Flashback prevention plates 11 are attached to opposite sides of the combustion air passageway 10, which are inclined from the center of the combustion air passage 10 toward the air-fuel mixture road 6.

In the above configuration, the primary air pressure of the air-fuel mixture inside the air-fuel mixture chamber 3 is set at 30 to 60%. A part of this air-fuel mixture is ejected from the flame port 1, and the remaining air-fuel mixture passes through the air-fuel mixture passage 6 and is ejected into the combustion air passage 10, and then mixes with the air in the combustion air passage IO to form the primary air. ratio 170 to 250%
The air-fuel mixture is reduced to a certain degree and below the flammability limit, and is ejected from the combustion air passage outlet 8. Here, the flow of air through the flashback prevention plate 11 will be explained. Combustion airway mIO
A part of the combustion air that has risen passes between the flashback prevention plate 11 and the burner body 2, and flows in the direction of the mixture road 6 by the flashback prevention plate 11 inclined toward the mixture road 6. It passes vertically through the outlet and is guided to the combustion air passage outlet 8, and the other part passes between the flashback prevention plate 11 and another flashback prevention plate 11 and flows to the combustion air passage outlet 8.

Here, the principle of generation of NOx generated from flame will be explained. NOx generated from flame is generally fuel N.
There are OX and thermal NOX, and the amount of fuel NOX generated depends on the type of fuel. Thermal NOX is NOX produced by reaction of N2 in the air when passing through a flame reaction zone, and the amount of thermal NOX generated is determined by the temperature of the flame reaction zone. Note that the amount of thermal NOX generated decreases as the temperature of the flame reaction zone decreases. Therefore, when a flame is burned in an atmosphere with a low oxygen concentration, the reaction becomes slow and the flame reaction zone becomes large, resulting in a decrease in the amount of heat generated per unit flame reaction zone. For these reasons, the temperature of the flame reaction zone is lowered, and NOx can be reduced.

Therefore, the flame formed in the burner having the above-mentioned configuration is caused by a part of the air in the combustion air passage IO being caused by the flashback prevention plate 11.
The course direction is guided to the exit of the mixture road 6, and the air flow becomes a high-velocity air flow that intersects perpendicularly with the mixture jetting out from the mixture passage 6, so the flame formed in the mixture passage 6 is caused by the vertical air. It is blown away by the current. Therefore, not only when the combustion amount is at its maximum, but also when the combustion amount is reduced, there is no backfire in the mixture road 6, and the mixture ejected from the mixture road 6 and the combustion air mix, leaving a thin layer of unburned air. The air-fuel mixture is supplied to the flame in the flame port 1 from the combustion air passage outlet 8. Also, between the flame port l and the combustion air passage outlet 8, there are
By providing the rim part 9 with a flame holding distance of m, the flame opening part 1
generates a recirculation area for each air-fuel mixture ejected from the combustion air passage outlet 8, and the flow of the air-fuel mixture at the combustion air passage outlet 8 directly hits the flame formed at the flame port 1, causing the flame to be blown away. This prevents the combustion from occurring, stabilizes the flame, and supplies the unburned air-fuel mixture with low oxygen concentration ejected from the combustion air passage outlet 8 to the flame formed on the flame port 1, thereby promoting combustion. This reduces the generation of thermal NOx by slowing down the flame temperature and lowering the flame temperature.

Effects of the Invention As described above, the low NOx combustor of the present invention provides the following effects.

(1) The flashback prevention plate guides some of the air in the combustion air passage toward the exit of the mixture passage, creating a high-velocity airflow that is perpendicular to the mixture jetting out from the mixture passage. By crossing, they blow out the flames that form in the mixture passage. Therefore, not only when the combustion amount is at its maximum, but also when the combustion amount is reduced, there is an effect of preventing backfire in the air-fuel mixture passage.

(2) By providing a rim part that provides a flame holding distance between the flame port and the combustion air passage outlet, a recirculation area for each mixture is created, and the flow of the mixture at the combustion air passage exit is controlled by the flame opening. It is possible to prevent the flame from being blown away due to direct contact with the flame formed in the area, thereby stabilizing the flame.

(3) By supplying the unburned air-fuel mixture with a low oxygen concentration ejected from the combustion air passage to the flame formed on the flame nozzle, the combustion reaction is slowed down, the flame temperature decreases, and NOx is generated.
can reduce the occurrence of

As described above, the present invention can provide a low NOx combustor that can reduce NOx in exhaust gas, prevent backfire of flame toward the exit of the mixture passage, and improve the durability of the burner.

[Brief explanation of drawings]

Figure 1 is a cross-sectional perspective view of the main part of the burner main body of a low NOx combustor in an embodiment of the present invention, and Figure 2 is a perspective view of the same low NOx
FIG. 3 is an enlarged cross-sectional view of the burner main body of the OX combustor, and FIG. 3 is a perspective view of a main part of the burner main body of the conventional low NOx combustor. 1... Burner port, 2... Burner body, 3
...Mixture chamber, 6...Mixture passage, 9.
...Rim part, IO...Combustion air passage, 1
1...Flashback prevention plate. Name of agent: Patent attorney Akira Okaji and two others Burner body SfL Gen! ! Famous jk road rim part fixing 7 air resistance reverse, 1' prevention

Claims (1)

[Claims] A large number of burners arranged in parallel, a combustion air passage provided between the burners, a flame port formed of a large number of flame ports provided in the burner, and the interior of the burner downstream of the burner port. a mixture chamber provided in the mixture chamber, a mixture passage communicating with the combustion air passage on the side of the mixture chamber, and a mixture passage that communicates with the combustion air passage within the combustion air passage and upstream of the mixture passage. A low NO_X combustor comprising: a flashback prevention plate inclined from the center of the passage toward the mixture passage; and a rim portion provided between the flame port and the combustion air passage.