JPS595801B2 - Low NOX burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to reduce nitrogen oxides (N
The present invention relates to a low NOx gas burner that reduces the generation of NOx while stabilizing the flame.

Conventional gas combustion with burners has been focused on stable combustion and complete combustion, but in terms of terminology, it often generates a high temperature range and produces high NOx, which is a problem due to NOx pollution.
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As a combustion method for reducing NOx, the diffusion combustion method is used as a method to lower the combustion speed, and one method is the diffusion combustion method, in which gas is injected into the furnace and combustion air is supplied from the burner throat. Compared to the method, combustion is slow and has an effective factor in reducing NOx.

Another method is the premix combustion method, in which the combustion gas is premixed with combustion air and combusted, but this method has a faster combustion reaction than diffusion silent combustion, but it requires mixing excess combustion air or a part of the exhaust gas. This is a method of reducing NOx by mixing it into combustion air to lower the calorific value per unit volume, thereby lowering the flame temperature.

However, with the premix combustion method, there is a risk of explosion of the device due to backfire, so countermeasures must be taken in advance.

The present invention aims at reducing NOx by combining the advantages of the diffusion combustion method with respect to NOx reduction and the advantages of the premix combustion method with respect to NOx reduction.

To explain the present invention based on the drawings, FIG. 2 is a view of the burner according to the present invention from inside the furnace, and FIG. 1, FIG. 3, and FIG. 4 are longitudinal cross-sections of the burner in various states. It is a diagram.

Several gas burners 3 a are installed in the burner throat 14 , which is a circular hole with a longitudinal cross section in the center of the furnace 1 .
, 3bt3c, 3d (four pieces in the figure) are arranged at equal intervals, and in the center is a heavy oil burner 10 having a flame-holding plate on the top.
is provided.

The outside of the burner throat 14 is a wind box 2.
There is an air register 9 provided circumferentially.

Gas burners 3a, 3b, . . ., having gas injection holes 4a, 4b, . ing.

Gas burner 3a. Movable tubes 8a, 8b, .
is slidably attached to the gas injection hole 4a for premix combustion.

A premixing tube 6 having a cylindrical surface and a conical surface is installed around the position of each gas burner 3a, 3b...
・It is located around the.

11a on the drawing. 11b, 11c, 11d, 11e,
11f.

11g, 11h, and 11i each represent a flow path for combustion air, and 13 a > 13 b . . . represents a flow path for fuel gas.

The gas burner 3a shown in FIG. 1 is a low NOx gas burner having such a structure.

The gas burner 3a is arranged so that the gas injection holes 4a, 4b, .

3b..., and move the movable tubes 8a, 8b... to positions where the premix air adjustment cone 7 works effectively.
When the combustion air is adjusted, combustion air from the wind box 2 passes through the air register 9, passes through the flow paths 11a to 11i shown in FIG. 1, and enters the furnace 1 through the burner throat 14.

On the other hand, the fuel gas passes through the passages 13a, 13b, . . . , burners 3a, 3b, .

In this case, the combustion air flow path 11c as shown in the figure.

11 d t 11 e and 11 f are premixed with the fuel gas coming out from the gas injection holes 4 a, 4 b .

Next, as shown in Fig. 3, move the movable pipes aa, sb, and
When .

Fig. 4 shows the case where the gas burner 3a in Fig. 1 is inserted into the furnace and adjusted so that the gas injection hole 4a is located away from the premixing tube 6, and it is easy to understand when compared with the gas burner 3b. .

In this case, since the gas burner 3a is not premixed, normal diffusion combustion occurs, while the gas burner 3b performs premix combustion.

In this way, the present invention makes it possible to create premixed combustion and diffusion combustion in which the proportion of premixed air is changed without worrying about backfire by varying the relative position between the burner fuel injection hole and the premixing guide member. The effectiveness of both combustion methods in reducing NOx can be utilized, and the effect can be large.

[Brief explanation of drawings]

Figure 2 shows an embodiment of the present invention as seen from inside the furnace. Figure 1 shows the case where premix combustion is the main type, Figure 3 shows the case where the proportion of premix combustion is small, and Figure 4 shows the case where the proportion of premix combustion is small. FIG. 3 is a longitudinal sectional view illustrating the positions of a gas burner and a cone for adjusting premixed air when used together with premixed combustion. 1...Furnace, 2...-Wind box, 3a, 3b
...Gas burner, 4a, 4b...-Gas injection hole, 5...Flexible tube, 6...Premixing tube, 7... Premix air adjustment cone, 8a, 8b
......Movable tube, 9...Air register, 1
0...Heavy oil burner, 11a-11i...
・Air flow path, 12...flame holding plate, 13a, 13b
...Fuel gas Ktllr, 14... Burner throat.

Claims (1)

[Claims] 1. A burner and a premixing guide member disposed surrounding the burner are provided across the wind box and the burner throat, and at least one of the burner and the premixing guide member is moved along the axial direction of the burner to achieve diffusive combustion. A low NOX burner characterized by performing premix combustion.