JPH037843B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intermediate mixing type gas burner.

(Prior Art and its Problems) Conventionally, there is a type of nozzle-mix gas burner shown in FIG. 5, for example.

That is, in the figure, 1 is a gas fuel pipe, and a tip 2 equipped with a gas nozzle 3 that opens diagonally outward is attached to the tip of this tube 1, and a mixing chamber 5 is provided inside the tip 2 on its outer periphery. A cup-shaped combustion air nozzle ring 4 is attached.

On the other hand, an outer tube 7 that forms a combustion air passage 8 with the gas fuel pipe 1 is attached to the outer periphery of the tip of the combustion air nozzle ring 4 . Further, the combustion air nozzle ring 4 is provided with an air nozzle 6 that is inclined in the tangential direction of the circumference.

Note that 9 is a combustion air supply port provided in the outer tube 7, and 10 is a closing plate for closing the end of the outer tube 7.

With the above configuration, fuel gas is ejected from the gas nozzle 3 into the mixing chamber 5, where it is sufficiently mixed with swirling combustion air ejected from the air nozzle 6, ignited at the mixing chamber outlet 11, and combusted in the combustion chamber 12. do.

However, in the above type of burner,
Even if a strong swirling force is applied by the combustion air nozzle, operating at an air ratio of 1.0 or less will result in poor mixing of fuel gas and air.
As the flame extends inside the furnace, the free oxygen concentration increases. Therefore, in order to use the material optimally as a gas burner that heats the material over a non-oxidizing direct flame,
Coverage constraints may arise, and turning down the burner further exacerbates this tendency.

On the other hand, a premix burner that supplies a complete premixture does not produce free oxygen as mentioned above and is capable of high-load combustion, but when it is turned down, there is a high risk of flashback occurring. and,
The use of high-temperature preheated air is not possible from a safety standpoint, and has the problem of various problems in achieving energy savings.

The present invention can also operate at an air ratio of 1.0 or less.
An object of the present invention is to provide a gas burner that hardly generates free oxygen, can perform high-load combustion, and can use preheated air.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a burner in which gas fuel is supplied through a pipe and combustion air is supplied through a passage formed around the gas fuel pipe. , an air nozzle communicating with the combustion air passage is provided in a burner chip provided at the tip of the burner, and a gas nozzle communicating with the gas fuel pipe, the nozzle having an acute angle with the upstream side thereof, and , a mixing port is formed downstream of the confluence of both nozzles, and the combustion air and gas fuel are collided and mixed at this mixing port, and this air-fuel mixture is
The fuel is ejected from the port outlet at a high speed of 100 m/s to 220 m/s, and is operated at an air ratio of 1.0 or less.

(Example) Next, the present invention will be explained with reference to drawings which are examples.

FIG. 1 shows an intermediate mixing type gas burner 20 according to the present invention, in which 21 is a gas fuel pipe, 22 is a burner chip, and the burner chip 22 is provided with a gas header 23 in the center thereof. and,
The tip of the gas fuel pipe 21 is inserted and fixed into the gas header 23 by appropriate means.

Reference numeral 30 denotes a burner outer tube, the tip of which is fixed to the outer periphery of the burner tip 22, and the rear end of which is connected to the flange portion 3 of the burner outer tube 30 by a seal plate 32.
1, and a combustion air passage 33 is formed between it and the gas fuel pipe 21. In addition, 3
4 is a combustion air supply pipe provided in the burner outer tube 30.

In the burner chip 22, an air nozzle 24 communicating with the combustion air passage 33 has a spread angle α° of 10° to 30° with respect to the burner axis (see Fig. 2), and has a cross section perpendicular to the burner axis. It is provided so that it has an inclination angle β° of 7° to 35° with respect to the radial direction (see FIG. 3). In addition, in order to obtain a wider stable range of non-oxidation heating, it is desirable that the inclination angle is 13° to 20°. Further, the burner tip 22 is provided with a gas nozzle 25 that communicates the gas header 23 and the air nozzle 24. This gas nozzle 25 communicates with the air nozzle 24 at an acute angle θ°, and forms a mixing port 26 on the extension line of the combustion air passage downstream of this communication (merging) point.

The burner 20 having the above configuration is inserted into a mounting hole 36 provided in a furnace wall 35 and fixed by a sealing mechanism 38. Note that 37 is a combustion chamber.

In the above configuration, when gas fuel and combustion air are supplied with an air-fuel ratio of 1.0 or less, the gas fuel passes through the gas nozzle 25 and joins with the combustion air, and is thoroughly mixed at the mixing port 26 before passing through the port outlet 27. The fuel is jetted out while swirling into the combustion chamber 37 at high speed and is combusted.

In this case, the jet speed of the air-fuel mixture at the port outlet 27 is set in a range of 100 m/s to 220 m/s. This is because if the ejection speed is too high, the flame holding function will be inhibited and a so-called blow-off phenomenon will occur.On the other hand, if the ejection speed is too small, the fuel gas and air will not be mixed in the mixing port 26. This is because the amount of free oxygen from the flame increases. Therefore, for non-oxidizing direct flame heating, it is approximately 100m/s~
Ejection velocities in the range of 220 m/s are particularly effective.
Furthermore, as described below, in the burner according to the present invention, since it is possible to use high-temperature preheated combustion air, the maximum speed at this time is about 220 m/s,
Maximum speed when using normal temperature combustion air is 130m/
It is s.

As described above, the mixed gas ejected from the port outlet 27 is sufficiently mixed at the mixing port 26, and is ejected and combusted at an optimal speed, so that oxygen in the mixed gas is not liberated during the process.

In addition, as shown in FIG. 4, the burner tip 22
A plurality of air-only nozzles 28 are provided in the burner tip 22, and these nozzles 28 are communicated with an annular groove 29 provided on the outer periphery of the burner tip 22, so that about 25% of the total combustion air is ejected from the annular groove 29. This air then flows at low speed along the inner surface of the burner tile and burns the rich unburned mixture flowing back.
This air can burn backflow mixtures even in the range of 10 to ~30%. Alternatively, this air may be supplied by swirling it.

Therefore, by doing this, the strongly reducing combustion gas hits the heating material, so that the non-oxidation heating performance can be improved.

(Effects of the Invention) As is clear from the above explanation, according to the present invention, gas fuel and combustion air are mixed at high speed inside the burner chip, so complete premixing can be performed. Since Qi is ejected from the port outlet at high speed, combustion is completed in an extremely short time.
Therefore, there is almost no free oxygen floating in the furnace, making it ideal for direct fire non-oxidation heating operated at an air ratio of 1.0 or less.

Furthermore, since the mixture is ejected from the port at high speed, no backfire will occur inside the burner chip even during turndown.

Furthermore, since the gaseous fuel and the combustion air are not mixed in advance but are mixed in a high-speed flow in the middle of the air nozzle, high-temperature preheated air can be used as the combustion air.

Furthermore, if a part of the combustion air is supplied into the furnace from the outer periphery of the burner chip, the amount of air supplied to the air nozzle will be reduced by the amount corresponding to the amount of air, and the amount of air-fuel mixture ejected from the mixing port will be reduced. Since the air ratio can be lowered, that is, an oxygen-deficient state is created, highly reducing combustion gas hits the heating material in the furnace, and the non-oxidation heating performance can be further improved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an intermediate mixing type gas burner according to the present invention, Fig. 2 is a partially enlarged sectional view of Fig. 1, Fig. 3 is a front view of Fig. 2, and Fig. 4 is a partially enlarged view of a modified example. FIG. 5 is a cross-sectional view of a conventional nozzle mix type burner. 21... Gas fuel pipe, 22... Burna tip,
23... Gas header, 24... Air nozzle, 26
...Mixing port, 28...Air-only nozzle, 29
...Annular groove, 30...Burner outer tube, 33...Combustion air passage.

Claims (1)

[Claims] 1. In a burner in which gas fuel is supplied through a pipe and combustion air is supplied through a passage formed around the gas fuel pipe, a burner chip provided at the tip of the burner is provided with a burner chip that communicates with the combustion air passage and extends along the burner axis. It has a spread angle α° of 10° to 30°,
And, 7° to radial direction in the cross section perpendicular to the burner axis.
An air nozzle is provided so as to have an inclination angle of 35 degrees, and a gas nozzle communicating with the gas fuel pipe is provided with an acute angle communicating with the upstream side of the nozzle, and the combustion air is provided downstream of the confluence of both nozzles. A mixing port is formed on the extension line of the combustion air passage, and the combustion air and gas fuel are collided and mixed at this mixing port, and this air-fuel mixture is
Make it eject from the port outlet at a high speed of s,
An intermediate mixing type gas burner characterized in that the burner is operated at an air ratio of 1.0 or less.