JPH06201111A - Gas burner - Google Patents

Abstract

PURPOSE:To carry out a high load combustion by a method wherein a mixed gas, diluted with the air, is formed at the rear side of a burner top by a fuel gas ejected through an auxiliary ejecting hole. CONSTITUTION:A fuel gas, ejected out of the auxiliary ejecting hole 5 of a fine diametral tube 1, collides against the rear end surface of a burner top 2 and is mixed with the combustion air whereby a diluted mixed gas is formed. The diluted mixed gas is ejected toward the fore side of the burner top 2 through a narrow gap between the peripheral surface of the burner top 2 and a combustion tube 6 along the inner periphery of the combustion tube and is mixed with fuel gas, ejected outward obliquely from main flame ports 4, then, is burnt. In this case, the combustion air is premixed with part of the fuel gas already and, therefore, mixing condition upon combustion is good, the speed of going upstream of flame is high and flame keeping can be effected surely even when the supplying amounts of fuel and air are increased to effect high-load combustion. According to this method, high-load combustion can be effected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a premix type gas burner for an industrial furnace.

[0002]

2. Description of the Related Art Generally, in an industrial furnace, a high load combustion burner having a large turndown ratio and a short flame length is required.
In a low-cost premixed gas burner that does not use a main mixer, it is necessary to secure strong flame holding by rapid and smooth mixing of fuel gas and combustion air. Type or air cone type burners were used. However, in the swirl flame type, swirl chambers, swirl vanes, etc. are necessary to obtain sufficient swirl air, and the air window box becomes large,
There is a problem such as costly blade processing.In the air cone type, the fuel gas discharged from the burner center and the combustion air supplied from the vent holes of the cone are mixed in stages, so sufficient mixing is required. In order to do so, it is necessary to make the length of the air cone large, which causes the problem that the diameter of the combustion chamber also becomes large. Further, in each case, there are disadvantages that the number of parts is large, the device is large, and the cost is high.

[0003]

Therefore, a gas burner having a structure as shown in FIG. 3 has recently been developed as a burner having a simple structure and capable of performing rapid mixing. This is provided with a disc-shaped flame holding plate 9 on the outer circumferential surface of the cylindrical burner top 2 with a slight gap left between the burner top 2 and the inner circumferential surface of the combustion cylinder 6. The air holes 10 are provided, and the combustion air supplied from the rear end of the combustion cylinder 6 is disturbed when passing through the air holes 10 of the flame holding plate 9 and the gap between the peripheral edges thereof, and the fuel is thereby disturbed. Although flame-holding is ensured by promoting mixing with gas, it is still unsatisfactory in flame-holding, flame length, turndown ratio, etc. The present invention is shown in FIG.
It is an object of the present invention to provide a gas burner which is not inferior to the conventional example and which is more compact and has excellent flame holding performance.

[0004]

As shown in FIG. 1, a gas burner according to the present invention has a large diameter cylindrical burner top 2 provided at the tip of a small diameter tube 1 with a tapered portion 3 formed at the front end periphery thereof. A plurality of main flame holes 4 obliquely forward and outward in the tapered portion 3.
And a plurality of auxiliary ejection holes 5 arranged in a row on the peripheral surface of the small-diameter tube 1 are arranged concentrically in a combustion tube 6 to which combustion air is supplied from the rear. Then, the burner top 2 is made to flow by the fuel gas ejected from the auxiliary ejection holes 5.
A thin mixed gas is formed in the rear of the.

[0005]

According to the above construction, the cylindrical burner top 2
Is supplied with a lean mixed gas from the rear side, and the main flame hole 4 is in the tapered portion 3 and jets the fuel gas obliquely, so that this collides with the flow of the combustion air to promote the mixing, and thereby the strong mixing is achieved. A good flame holding is secured, and a large turndown ratio is possible. Further, the rear end surface of the burner top has the same function as the flame holding plate 9 in the conventional example of FIG.
And promotes mixing. Also flame holding plate 9
Since it is unnecessary, the size can be reduced, and the area of the front surface of the burner top is increased to increase the negative pressure circulation region B in front of the nozzle. Therefore, even if the jet speed of the main flame hole is increased, the flame is increased. Does not become long, and high-load combustion becomes possible.

[0006]

FIG. 1 shows an embodiment of a gas burner according to the present invention, in which a nozzle A is a so-called horsetail type in which a large diameter cylindrical burner top 2 is formed at the tip of a small diameter tube 1. A taper portion 3 is formed on the peripheral edge of the front end of the top 2, and a plurality of main flame holes 4 extending diagonally forward and outward are arranged in a row in the taper portion 3. The holes 5 are arranged in a row. The nozzles are concentrically arranged in the combustion cylinder 6, and a slight gap is provided between the outer peripheral surface of the burner top 2 and the inner peripheral surface of the combustion cylinder 6, and the nozzle is provided at the rear end of the small diameter tube 1. The fuel gas is supplied by the gas pipe 7, and the combustion air is supplied to the rear end of the combustion cylinder 6 through the air window 8.

The amount of fuel gas ejected from the auxiliary ejection hole 5 of the small-diameter tube 1 is about half of the amount ejected from the main flame hole 4, and this collides with the rear end surface of the burner top 2 together with the combustion air. Then, a lean mixed gas is formed. This lean mixed gas is ejected toward the front of the burner top 2 along the inner circumference of the combustion cylinder 6 through the narrow gap between the peripheral surface of the burner top 2 and the combustion cylinder 6, and here from the main flame hole 4. It mixes with the fuel gas ejected obliquely outward and burns. At this time, since the combustion air already has a part of the fuel gas premixed, the mixing condition during combustion is extremely good. The flame upstream speed is high, and even if high load combustion is performed by increasing the fuel and air supply amounts accordingly, flame holding is reliably performed. Further, since the combustion gas has a high velocity in the outer peripheral portion along the combustion tube 6,
Negative pressure is generated in the central portion to form the circulation region B, and strong flame holding is also performed in this portion.

Comparing this with the conventional example of FIG. 3, the point that a negative pressure is generated at the rear A of the conventional flame holding plate 9 and the air flow is disturbed is the same in the rear end surface of the burner top 2 in the present invention. In the burner of the present invention, the mixing of the combustion air and a part of the fuel gas already starts behind the burner top 2 and passes through the gap between the burner top 2 and the combustion tube 6. Since the fuel gas is sufficiently diffused, the mixed state in front of the main flame hole 4 is much better, and firm flame holding can be secured. Further, since the flame holding plate 9 is not required, the outer diameter size can be made small and the front end surface of the burner top 2 can have a large area, so that the circulation area B in front of the burner becomes large, and the flame is short and the load is high. The combustion of is obtained.

[0009]

As described above, according to the present invention, a part of the fuel gas is mixed into the combustion air behind the burner top 2 and the combustion air is disturbed at the rear end surface of the burner top 2 to be burned to the burner top 2. Since it is sufficiently mixed while passing through the gap with the combustion cylinder 6, it has a flame holding effect equivalent to that of the original mixing without using the original mixer, and since the flame holding plate 9 is not required, it can be downsized. In addition to being possible, since the front area of the burner top is large, there is an advantage that the circulation area B can be made large, and the flame is shortened accordingly, and high load combustion is possible. There is an advantage that the performance can be provided by a small and simple structure.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a front view of the above.

FIG. 3 is a sectional view of a conventional example.

[Explanation of symbols]

 1 Small Diameter Tube 2 Burner Top 3 Tapered Part 4 Main Flame Hole 5 Auxiliary Jet Hole 6 Combustion Cylinder

Claims (1)

[Claims] 1. A large-diameter cylindrical burner top provided at the tip of a small-diameter pipe is provided with a taper portion at the front end peripheral edge thereof, and a plurality of main flame holes extending diagonally forward and outward are provided in the taper portion. , A nozzle having a plurality of auxiliary ejection holes arranged in a row on the peripheral surface of the small-diameter pipe is concentrically arranged in a combustion cylinder to which combustion air is supplied from the rear, and ejected from the auxiliary ejection hole. A gas burner characterized in that a lean mixed gas is formed behind the burner top by the burning fuel gas.