JPH0441242B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Fields of Use The present invention is applicable to industrial, commercial or domestic use.
It concerns the NO _x burner.

Conventional Technology Conventionally, a burner 1 utilizing complete premix combustion has been used as a low _NOx burner. For example, as shown in FIG. 5, a combustion chamber 3 consisting of a burner wall 2 is
A wire mesh 4 was provided in a part of the combustion chamber, and the fuel 5 supplied to the combustion chamber was ignited on the surface of the wire mesh to form a flame 6.

Such burners burn fuel with excess air and radiate the heat received from the flame through a wire mesh, thereby lowering the flame temperature and reducing NO _x emissions.

Problems to be Solved by the Invention However, when the amount of combustion is large or when the excess air ratio approaches 1, the temperature of the wire mesh rises rapidly and flashback often occurs, or the wire mesh oxidizes due to the high temperature. However, there was a problem with durability. On the other hand, if the amount of premixed air is increased to increase the excess air ratio, or if the amount of fuel is increased to increase the fuel flow velocity, the flame becomes unstable and unburned gas is emitted. This often led to blowouts. As a result, the variable range of combustion amount and air amount is small, which causes practical inconvenience.

Heat is also radiated from the wire mesh to the upstream side, that is, to the combustion chamber, heating the fuel. As a result, it had the disadvantage that the decrease in flame temperature was small and the reduction in NO _x was small.

Means for Solving the Problems The present invention provides a burner that emits less NO _x and has good flame stability.

A combustion chamber is formed by the combustion chamber wall and the combustion chamber outlet. A large number of flame ports are arranged on the combustion chamber wall at approximately constant distances, forming a row of flame ports. The walls of each combustion chamber are opposed to each other. Each flame port is located at the outlet of a fuel supply channel provided in the combustion chamber wall. The fuel supply path is provided outside the combustion chamber. A plurality of flame ports are arranged in the direction of the combustion chamber. Flame ports facing each other across the combustion chamber are not arranged on the same axis. Each burner port is arranged approximately in the center between each burner port in the row of opposing burner ports. Fuel has a large excess air ratio M (M>1)
It is preferable to burn it with

Effect When there is excess air in such a burner, the flame collides with the wall of the combustion chamber between the opposing flame ports and burns.
Then, high-temperature combustion gas is supplied to the flame formed at the opposing flame port, improving the stability of this flame. As a result, combustion is possible in an area with a large amount of air, and it is difficult to blow away even when the amount of combustion is large. In particular, the flame stability is good because the flame formed at the flame port near the combustion chamber outlet is preheated by the high temperature gas generated by the flame formed at the flame port distant from the combustion chamber outlet.

Furthermore, the flame is dispersed and heat is radiated from the combustion chamber and from the fuel supply path, thereby reducing _NOx emissions. Furthermore, when the amount of combustion is small or the excess air ratio is small, the flame approaches the flame nozzle and heats the flame nozzle, thereby promoting the reduction of NO _x by heat radiation from the flame nozzle.

Embodiment FIG. 1 is a configuration diagram of an embodiment of the present invention, and 7
is the burner body, 8 is the combustion chamber, 9 is the combustion chamber wall, 10
is the combustion chamber outlet, 11 is the flame port, 12 is the fuel supply path,
13 is a branch pipe, 14 is a cooling passage, and 15 is a vaporization cylinder.

FIG. 2 is a cross section taken along the line AA in FIG. 1, and FIG. 3 is a cross section taken along the line BB. 16 is a blower, 17 is a fuel nozzle, 18 is fuel, 19 is a mixture, and 20 is a flame. 21 is exhaust gas, and 22 is cooling air.
23 is a heater. High temperature exhaust gas 21 is often used as a heat source. Fuel 18 (for example, kerosene) is injected into the carburetor 15 from the fuel nozzle 17. The vaporizing cylinder 15 is made of aluminum die-casting, has a heater 23 embedded therein, and has a temperature of 200-300°C.
is heated to. Fuel 18 supplied to the carburetor cylinder 15
vaporizes. On the other hand, combustion air is introduced into the vaporization cylinder 15 from the blower 16 and mixed with the vaporized fuel 18 to form an air-fuel mixture 19. The mixture 19 is in the branch pipe 1
3, a large number of fuel supply channels 1 are provided in the branch pipe 13.
2 and is introduced into the combustion chamber 8 from the flame port 11 at the tip. The fuel supply passage 12 is constituted by a tube having an elongated passage outside the combustion chamber wall 9.

When this mixture 19 is ignited, a flame 20 is formed. When using gaseous fuel instead of liquid fuel 18, it is possible to burn it in the same way as liquid fuel 18 by omitting the vaporization tube 15.

The flame ports 11 face each other with the combustion chamber 8 interposed therebetween, and a large number of flame ports 11 are arranged on the combustion chamber wall 9 at approximately constant distances to form a row of flame ports. The fuel supply path 12 also corresponds to the flame port 11. A fuel supply passage 12 is arranged outside the combustion chamber wall 9. Fuel supply passages 12 are arranged in a group between the combustion chamber wall 9 and the branch pipe 13 to form a cooling passage 14 . Cooling air 22 passes through this cooling passage 14 . The branch pipe 13 is divided into several parts, and the cooling air 22 can pass between each branch pipe 13, and the heat radiated from the combustion chamber wall 9 can be radiated to the outside. Cooling air 22 is often heated and used as a heat source. many flames 20
is formed in the combustion chamber 8, and the heat generated by this flame 20 heats the combustion chamber wall 9 and the fuel supply passage 12. Then, heat is radiated from the combustion chamber wall 9 and the fuel supply path 12 to lower the flame temperature, and the exhaust gas 2
Aim to reduce NO _x contained in 1. Combustion chamber wall 9
The fuel supply path 12 is made of a heat-resistant material such as stainless steel, which facilitates heat dissipation by radiation at high temperatures. The outside of the combustion chamber wall 9 heated by the flame 20 is a cooling passage 14, through which cooling air 22 passes, cooling the combustion chamber wall 9, directly cooling the flame 20, and cooling the combustion chamber. Preheating of the mixture 19 by the wall 9 is also prevented. At this time, the fuel supply passage 12 is similarly cooled by the cooling air 22. The heat supplied from the flame 20 to the flame port 11 is transmitted upstream to the fuel supply path 12 by conduction, and the air-fuel mixture 19 is preheated. can be minimized.

The invention is characterized by the impingement of flame 20 on opposing combustion chamber walls 9. Next, this flame 20 will be explained in detail. FIG. 4 is a conceptual diagram of the main part of FIG. 2, showing the form of the flame 20 colliding with the combustion chamber wall 9. 24 is unburnt gas, 25 is the flame base, 2
6 is a flame collision part, and 27 is a high temperature gas.

The flame 20 formed on the flame port 11 is the flame base 2
5, the flame adheres to the flame port 11, collides with the combustion chamber wall 9, and forms a flame collision part 26. At this time, the flame 20 spreads along the combustion chamber wall 9, radiates the heat of the flame 20 to the combustion chamber wall 9, and lowers the temperature of the flame 20. As a result, NO _x is reduced.

In addition, the high-temperature gas 27 generated by the colliding flame 20 flows near the flame port 11 and heats the flame port 11 as well as the flame base 25 of the flame 20.
Stabilize the flame. Further, a portion of unburnt gas 24 is released from between the flame port 11 and the flame base 25, but is oxidized by the high temperature gas 27.

When the fuel flow rate decreases, the flame 20 moves toward the combustion chamber wall 9.
Without colliding with the flame, it gradually becomes shorter and tries to enter the flame outlet 11.

At this time, the combustion chamber wall 9 and the fuel supply passage 12 are cooled by the cooling air 22. Therefore, the flame 20 enters toward the upstream side of the fuel supply path 12, i.e.,
There is no backfire, and the flame burns stably near flame port 11.

The fuel supply path 12 has an elongated tubular shape, and if L is the length and D is the diameter, the air-fuel mixture 19 will have a Poiseuille flow if L/D is large. In Poiseuille flow, the flame base 25 comes closer to the flame port 11, which suppresses the discharge of unburned gas 24 and facilitates complete combustion. At this time, it was found that the effect was large when L/D≧4.

As shown in FIG. 3, high-temperature gas 27 generated by the flame 20 formed at the flame port 11 distant from the combustion chamber outlet 10 is transferred to the flame port 11 closer to the combustion chamber outlet 10.
1 and preheats the air-fuel mixture 19. As a result, the stability of the flame 20 near the combustion chamber 8 is ensured. The inflow of high temperature gas 27 is only near the flame base 25 and does not heat the entire flame 20, so the amount of NO _x discharged does not increase. At this time, when the flame port 11 is projected into the combustion chamber 8, the flame port 11 is heated and the stability of the flame 20 is increased.
1 can flow.

If the flame port 11 arranged on the combustion chamber wall 9 is arranged approximately midway between the flame ports provided on the opposing combustion chamber walls, it will not collide with the opposing flame.

Effects of the Invention The burner of the present invention forms a large number of opposing flames that collide with the combustion chamber wall within the combustion chamber, and the opposing flames are arranged on different axes, so that the NO _x reduction effect is large. In particular, a large reduction effect and good flame stability can be obtained at low excess air ratios.

[Brief explanation of the drawing]

FIG. 1 is a perspective configuration diagram of a burner according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1, FIG. 3 is a cross-sectional view taken along line B-B in FIG. 1, and FIG. 5 is a conceptual diagram of the main parts of the burner, and FIG. 5 is a diagram showing the structure of the main parts of the conventional burner. 7...burner body, 8...combustion chamber, 11...flame port, 12...fuel supply passage, 14...cooling passage.

Claims (1)

[Scope of Claims] 1. A combustion chamber is formed by a combustion chamber wall and a combustion chamber outlet that face each other, and a row of flame ports is formed by providing a large number of flame ports arranged at a substantially constant distance on the combustion chamber wall. The burner is characterized in that the flame ports are located at the exits of a large number of fuel supply passages provided in the combustion chamber wall, and the flame ports facing each other across the combustion chamber are arranged on different axes. 2. The burner according to claim 1, wherein the flame ports arranged on the combustion chamber wall are arranged approximately midway between the flame ports provided on the opposing combustion chamber walls.