JP2924138B2 - Low NOx burner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a Bunsen type low NOx burner.

2. Description of the Related Art Conventionally, a home burner of this type includes a first air-fuel mixture chamber 3 provided in a burner main body 2 having a first flame port 1 as shown in FIG. A second mixture chamber 5 having second flame ports 4 provided on both sides of the air chamber 3, and the burner main body communicating the first mixture chamber 3 and the second mixture chamber 5; 2 and an air inlet 7 for setting the primary air ratio of the second mixture chamber 5 in the second mixture chamber 5. In such a configuration, the combustion is slowed down by supplying the unburned mixture having a low oxygen concentration ejected from the second flame port 4 to the flame formed in the first flame port 1, The flame temperature was lowered, and the generation of thermal NOx was reduced.

Problems to be Solved by the Invention However, in the above configuration, although the effect of reducing NOx is satisfactory, the primary air ratio of the first air-fuel mixture chamber increases as the combustion amount is reduced. The flow velocity decreases, the mixing becomes uneven in the second mixture chamber, and a partial air ratio of the second mixture chamber enters the combustible region, and the flame passes from the first flame port to the second flame port. This causes a problem that the burner main body is abnormally heated by flashback at the outlet of the air-fuel mixture passage.

The present invention solves such a conventional problem, and reduces NOx in exhaust gas and prevents backfire of a flame to an outlet of an air-fuel mixture passage. The aim is to realize a NOx burner.

Means for Solving the Problems In order to solve the above problems, the low NOx burner of the present invention is provided on a first air-fuel mixture chamber having a first flame port, and provided on a side of the first air-fuel mixture chamber. A second mixture chamber having a second flame port, and a mixture passage communicating the first mixture chamber and the second mixture chamber; a second mixture chamber wall plate An air inlet for setting a primary air ratio of the second air-fuel mixture chamber provided in the second air-fuel mixture chamber, and at least one of the air-fuel mixture passage and the air air inlet has a flow parallel to a downstream side of the second mixing chamber. A plurality is provided at positions sequentially entering the air chamber.

Operation The present invention has the above-described configuration so that the air-fuel mixture, which is unburned and lower than the oxygen concentration in the atmosphere, and a part of the combustion air are supplied in parallel along the flow direction and each flow is subdivided. A plurality of mixture passages and air inlets are provided to sequentially enter the second mixture chamber and mix well, and are ejected from the second flame opening into a flame formed on the first flame opening. . At that time, by supplying an air-fuel mixture which is not burned and lower than the oxygen concentration in the atmosphere, the combustion is slowed down and the flame temperature is lowered.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

In FIGS. 1 and 2, reference numeral 8 denotes a burner main body. On the upper surface of the burner main body 8, there is provided a first flame opening 9 having a large number of slits. A plurality of mixture passages 10 are provided on both sides of the burner main body 8 on the same cross section toward the downstream side so that the mixture is divided and supplied in parallel along the flow direction of the mixture, and A plurality of mixture passages 10 having the same cross section are arranged at optimal intervals in the longitudinal direction of the burner main body 8 as well. Further, a second air-fuel mixture chamber wall plate 12 forming a second air-fuel mixture chamber 11 is attached to both side surfaces of the burner body 8. Upper end portion 13 of second mixture chamber wall plate 12 and burner body 8
A second flame port 14 is formed between them. In the lower part of the second mixture chamber wall plate 12, a plurality of air intake ports 15 provided substantially opposite to the mixture passage 10 are arranged at optimal intervals in the longitudinal direction of the burner main body 8. I have. Reference numeral 16 denotes a first mixture chamber.

In the above configuration, the air-fuel mixture in the first air-fuel mixture chamber 16 has a primary air ratio set to 30 to 60%. A part of the air-fuel mixture is blown out from the first flame opening 9, and the remaining air-fuel mixture is distributed from a plurality of air-fuel mixture passages 10 provided in the air-fuel mixture flow direction, and is guided to the second air-fuel mixture chamber 11. Sufficiently mixed with the incoming secondary air distributed from the plurality of air intakes 15 provided in the secondary air flow direction, and the primary air ratio is 170 to 250%.
The mixture becomes a uniform mixture having a degree of combustion and less than the flammable limit, and is ejected from the second flame port 14. The remainder of the secondary air flows along the outer periphery of the second mixture chamber wall plate 12 and is supplied as secondary air of the second flame port 14, and then the secondary air of the first flame port 9 Also acts as air.

Here, the generation principle of NOx generated from the flame will be described. NOx generated from a flame generally includes fuel NOx and thermal NOx, and the amount of fuel NOx generated depends on the type of fuel. Thermal NOx is NOx produced by the reaction of N2 in the air when passing through the flame reaction zone, and the amount generated is determined by the temperature of the flame reaction zone. The amount of thermal NOx generated decreases as the temperature of the flame reaction zone decreases. Therefore, when the flame is burned in a low oxygen concentration atmosphere, the reaction becomes slow, and the flame reaction zone becomes large, so that the calorific value per unit flame reaction zone decreases. For this reason, the temperature of the flame reaction zone decreases, and NOx can be reduced.

Therefore, in the above configuration, the air-fuel mixture and a part of the secondary air entering the second air-fuel mixture chamber 11 from the air-fuel mixture passage 10 and the air intake 15 are fragmented and sequentially mixed, so that the combustion amount at the maximum is In this case, of course, sufficient mixing is promoted even at the time of the minimum combustion at a low flow rate, and the air-fuel mixture ejected from the second flame port 14 can be made a uniform air-fuel mixture below the combustion flammable limit. The flame is prevented from flashing back through the mixture passage 10 through the passage 11. Further, since both the air-fuel mixture and the secondary air are dispersed and mixed, the rectification and the suppression of turbulence are promoted in the second air-fuel mixture chamber 11, the flame is stabilized, and the noise during combustion is reduced. The combustion reaction is slowed down and the flame temperature is lowered by supplying the unburned mixture having a low oxygen concentration ejected from the flame port 14 to the flame formed on the first flame port 9. This reduces the generation of thermal NOx.

Effects of the Invention As described above, according to the low NOx burner of the present invention, the following effects can be obtained.

(1) At least one of the air-fuel mixture passage and the air intake port is provided in a plurality of positions at which the flow sequentially enters the second air-fuel mixture chamber in parallel toward the downstream side. Mixing is promoted also in the air chamber, and even in the case of minimum combustion at a low flow velocity, the air-fuel mixture in the second air-fuel mixture chamber can be uniformly reduced to the flammable limit or less, and mixed through the second air-fuel mixture chamber. It is possible to prevent the flame from flashing back into the air passage. Also, since the mixture concentration in the second mixture chamber can be made uniform, it is possible to set the primary air ratio at which NOx can be reduced most, and NOx
Can be further reduced.

Further, the mixture passage and the air intake can be subdivided, the flow upstream of the flame opening is rectified, and turbulence due to collision or the like is suppressed, so that the flame itself can be stabilized and combustion noise can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional perspective view of a low NOx burner according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a main part of the burner, and FIG. 3 is a sectional perspective view of a conventional low NOx burner. 8 burner main body, 9 first flame outlet, 10 mixture passage, 11 second mixture chamber, 14 second flame outlet, 15
…… air intake, 16 …… first mixture chamber.

Continuation of the front page (56) References Japanese Utility Model Showa 64-8024 (JP, U) Japanese Utility Model Showa 64-8025 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F23D 14 / 02 F23D 14/08 F23D 14/62 F23C 11/00 329-330

Claims (1)

(57) [Claims] 1. A first mixing chamber provided in a burner body having a first flame port and a second mixing chamber having a second flame port provided beside the first gas mixture chamber. An air chamber, a mixture passage provided on a side surface of the burner main body that communicates the first mixture chamber and the second mixture chamber, and a primary air ratio of the second mixture chamber. An air intake port provided in a second air-fuel mixture chamber wall plate, at least one of the air-fuel mixture passage and the air intake port has a flow toward a downstream side in parallel to the second air-fuel chamber sequentially. A low NOx burner characterized by having a plurality at the entry position.