JP2000146117A - High speed ejection burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the service life of an air conditioner by dividing a combustion tube into primary and secondary combustion spaces and burning combustion gas in two stages thereby prevent generation of a local high temperature zone. SOLUTION: Substantially completely combusted gas from a combustion tube 1 having constricted forward end is ejected by the expansion pressure from an opening 2 at the forward end of the combustion tube 1. A conical air cone 4 is provided at the forward end of a combustion nozzle 3 and an inner tube 5 for dividing the combustion air into primary and secondary airs is disposed between the large diameter section of the combustion tube 1 and the air cone 4. When the total area of a vent 7 at the base end part of the inner tube 5 is designed appropriately, about 30% of the total air is supplied as primary air to the inner tube 5 and combustion takes places under oxygen deficient state. A plurality of vents 6 made in the air cone 4 stir fuel gas and primary air as much as possible and mix them uniformly before being combusted. Since oxygen is deficient in the air cone 4 or the inner tube 5, primary combustion is relatively gentle and generation of high temperature zone can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed injection burner used in a general industrial furnace.

[0002]

2. Description of the Related Art FIG. 3 shows the structure of a conventional burner of this type, in which a conical air cone 4 is provided at the tip of a fuel nozzle 3 and the opening 2 is narrowed by narrowing the tip. The air cone 4 is disposed at the large diameter portion of the air cone 4, air is introduced from a plurality of ventilation holes 6 provided on the conical surface of the air cone 4, mixed with fuel gas by stirring, and almost completely burned in the combustion tube 1. , From the tip opening 2. According to this configuration, the combustion gas is injected at a high speed by the expansion pressure, so that the temperature distribution of the object to be treated can be made uniform by the effect of stirring in the furnace, and the thermal efficiency can be improved by the convection heat transfer effect.

[0003]

However, this type of high-speed injection burner requires almost complete combustion in the combustion cylinder 1 in order to obtain the injection pressure. The combustion cylinder 1 has a problem that it is necessary to use an expensive heat-resistant material, or to use a burner tile which is heavy and large and requires high assembly cost, or a ceramic material which is easily broken. In addition, since it is mixed with the theoretical air amount and burned at once in the burner, there is a drawback that the combustion noise is large and the working environment is deteriorated. An object of the present invention is to solve these problems.

[0004]

As shown in FIG. 1, the high-speed injection burner according to the present invention is a premixed high-speed injection burner in which the opening 2 is narrowed by narrowing the tip of a combustion cylinder 1.
A conical air cone 4 is provided at the tip of the fuel nozzle 3, and an inner cylinder 5 for separating combustion air into primary and secondary air is provided between the large diameter portion of the combustion cylinder 1 and the air cone 4. A part of the primary air is introduced from a plurality of ventilation holes 6 provided in the conical surface of FIG. With this configuration, the combustion noise is remarkably reduced by this configuration, and at the same time, inexpensive general-purpose stainless steel can be used as the material of the air cone 4 and the combustion cylinder 1 or the inner cylinder 5.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, in which gas almost completely burned in a combustion cylinder 1 having a narrowed tip is compressed by an expansion pressure thereof so that a tip opening 2 of the combustion cylinder 1 is opened. The conical air cone 4 is provided at the tip of the fuel nozzle 3 as in the conventional example. However, in the present invention, the large diameter portion of the combustion cylinder 1 and the air cone 4 are provided. A cylindrical inner cylinder 5 for separating the combustion air into primary and secondary air is provided therebetween, and the total area of the ventilation holes 7 formed in the closed base end of the inner cylinder 5 is appropriately designed. By doing
In the inner cylinder 5, for example, about 30% of the total air amount is supplied as primary air, and burns in a state of insufficient oxygen. The plurality of ventilation holes 6 provided in the conical surface of the air cone 4 are for stirring and mixing the fuel gas and the primary air as much as possible to uniformly burn the fuel gas and the primary air. However, oxygen is insufficient in the air cone 4 or the inner cylinder 5. Therefore, the primary combustion is relatively slow. After the primary combustion is further almost completely burned in the combustion cylinder 1 by the secondary combustion, the primary combustion is ejected from the front end opening 2 of the combustion cylinder 1 at a high speed. 9 in the figure
Is a spark rod.

Further, according to the present invention, a concentration gradient is formed in the combustion cylinder 1 to reduce the combustion speed along the axial direction, thereby preventing the oscillating combustion which caused the combustion noise and stabilizing the combustion. As a result, it is possible to further narrow the tip opening 2 to increase the ejection speed. As an example, the burner opening equivalent to 100 × 10 ² kcal / m ² h according to the conventional configuration is squeezed to 150 × 10 ² kcal / m ² h as the sectional load of the combustion amount in the opening ² .
30%: 70 ratio of primary air and secondary air by inner cylinder 5
As a percentage, a burner with much lower combustion noise and stable combustion was obtained. At this time, the NOx emission amount is 3
It decreased by 0%. As the ratio of primary air to secondary air,
The less primary air, the more stable the combustion and the lower the temperature of the combustion cylinder 1. However, if it is less than 10%, the primary flame does not sustain flame and becomes a combustion load. Is required.

In the embodiment shown in FIG. 2, the shape of the tip nozzle hole 8 of the fuel nozzle 3 is improved in order to improve the flame holding performance of the air cone 4 when the primary air ratio is reduced. FIG. 2A shows the nozzle hole 8 at an angle of α degrees (spread angle) outward.
Tilt it and mix it with the airflow that flows in from the surroundings,
FIG. 4B shows a configuration in which the nozzle hole 8 is inclined by β degrees (swirl angle) in the circumferential direction so as to swirl the flame. Can be further increased by about 10%. At this time, the divergence angle α or the swirl angle β is set to 20 so that the flame does not spread after being ejected from the combustion cylinder 1 to the outside.
Degrees or less, the secondary air ratio must be 70 to 90%, and the injection speed must be 20 m / s or more.

[0008]

According to the present invention, as described above, the combustion cylinder 1
The interior is divided into a primary combustion space and a secondary combustion space by the inner cylinder 5 so that the fuel gas is burned in two stages. The generation of a high temperature region is prevented, whereby the life of the air cone 4 can be extended, or the material can be changed to a cheap material such as a general-purpose stainless steel. As the secondary air flow is formed, the temperature rise is moderated, and as a material for the combustion cylinder 1 or the air cone 4 which conventionally required a heat resistant temperature of 1000 ° C. or more, an inexpensive material such as general-purpose stainless steel (heat resistant temperature of 800 ° C. or less) ) Can be used. Further, since an oxygen concentration gradient is formed in the combustion cylinder 1 in the axial direction, the oscillating combustion near the air cone 4 is prevented, the combustion performance is improved, and the combustion noise can be significantly reduced. The jetting speed can be increased by further narrowing the area of the front end opening 2, and the uniformity of the furnace temperature distribution by the furnace air stirring effect can further improve the heating efficiency of the object to be processed, and at the same time, the furnace interior There is an advantage that the amount of generated NOx can be significantly reduced by the exhaust gas entrainment effect.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of a main part of another embodiment of the present invention.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combustion cylinder 2 Tip opening 3 Fuel nozzle 4 Air cone 5 Inner cylinder 6 Vent hole 7 Vent hole 8 Nozzle hole 9 Spark rod

Claims (3)

[Claims] In a high-speed injection burner of a premixing type in which an opening is narrowed by narrowing a tip of a combustion cylinder, a conical air cone is provided at a tip of a fuel nozzle, and between a large diameter portion of the combustion cylinder and the air cone. In addition, an inner cylinder that separates the combustion air into primary and secondary air is provided, and a part of the primary air is introduced from a plurality of ventilation holes provided in the conical surface of the air cone, and the air-fuel mixture mixed by the air cone is injected into the inner cylinder. A high-speed injection burner in which primary combustion is performed in the combustion chamber and secondary combustion is performed in the combustion cylinder. 2. The ratio of the primary air is 10 to 40
The high-speed injection burner according to claim 1, wherein 3. The high-speed injection burner according to claim 1, wherein the nozzle hole at the tip of the fuel nozzle is inclined outward or circumferentially.