CN201582822U - Concentric type axial rotational flow burner adopting high-temperature air combustion technology for industrial furnace - Google Patents

Abstract

The utility model relates to a concentric type axial rotational flow burner adopting the high-temperature air combustion technology for an industrial furnace. The burner comprises a central circular straight pipe (1), an outer-layer sleeve (2), a rotary passage (3), and spiral fins (4), wherein the central circular straight pipe (1) is arranged in the outer-layer sleeve (2) and is coaxial with the outer-layer sleeve (2). The burner can strengthen the thorough mixing of the gaseous fuel and the high-temperature air in a furnace chamber of the industrial furnace, so as to realize the stable burning under the lower inlet air oxygen density, ensure the more uniform temperature distribution in the furnace chamber, decrease the phenomenon of high temperature at local parts, and meanwhile greatly lower the discharge of the nitrogen oxides (NOXs) and realize the goal of energy conservation and environmental protection.

Description

Concentric Axial Swirl Burner for High Temperature Air Combustion Technology in Industrial Furnaces

technical field

The utility model belongs to the field of burner nozzles, in particular to a concentric axial swirl burner for industrial furnace high-temperature air combustion technology.

Background technique

Industrial furnaces are widely used in steel, metallurgy, machinery, ceramics, glass and other industries, and are key equipment for thermal processing. In industrial furnaces for heat treatment and various thermal processing processes, more and more gas combustion is used as a technical way of heating. High temperature air combustion (High temperature air combustion, HTAC) is an advanced combustion technology that uses high preheated air under ultra-low oxygen concentration conditions. It uses natural gas or coal gas as fuel and sends it into an industrial furnace for combustion in the form of a jet. And by using high-efficiency heat storage ceramic materials to limit the recovery of waste heat in the flue gas after combustion, and use it to heat the air entering the furnace, thus greatly saving energy. At the same time, because it is a high-intensity combustion under ultra-low oxygen concentration, the concentration of thermal nitrogen oxides (NO _x ) generated during the combustion process can be very low, and it has very low NO _x emission characteristics, so its environmental protection advantages are very significantly. In addition, under ultra-low oxygen conditions, the degree of oxidation of metal components is reduced, thereby improving the thermal processing quality of metals to a certain extent. High-temperature air combustion technology has developed rapidly in the past 20 years, and has broad application prospects in industrial furnaces in iron and steel metallurgy, glass, ceramics, cement and other industries.

According to relevant experiments, due to changing the injection conditions of gaseous fuel and preheated air, their mixing process in the furnace can be effectively changed, and the stability of combustion under ultra-low oxygen conditions, the uniformity of temperature distribution and the reduction of NO _X The amount of local generation has a big impact.

At present, the burner structure of high-temperature air-fired industrial furnaces used in engineering is usually high-temperature preheated air and gas fuel injected into the furnace at high speed in the form of direct jets. The turbulent movement of these jets in the limited space of the furnace causes smoke Gas recirculation and mixing between fuel, air and flue gas to ensure the temperature distribution in the furnace, local oxygen concentration distribution and other characteristics, so as to maintain stable combustion and local thermal NO _X generation under low oxygen conditions. The range and degree of reflow in the furnace caused by the mutual interference of multiple straight jets are relatively limited. If the high-temperature preheated air and fuel can be mixed more fully in the furnace, the local oxygen concentration and temperature distribution in the furnace will be more reasonable, so that the combustion can be achieved at a lower inlet oxygen concentration and reduce the local The amount of NO _X produced.

Swirls provide better mixing. In the burner nozzle structure designed by the present invention, the outer layer is several swirling high-temperature preheating air jets, and the center is a direct jet of gas. After they enter the furnace, a plurality of swirling jets surround a straight jet. In a confined space, more thorough mixing can be achieved than straight jet flow, so that stable combustion and lower NO _X emissions can be achieved at lower oxygen concentrations.

Contents of the invention

The technical problem to be solved by the utility model is to provide a concentric axial swirl burner for industrial furnace high-temperature air combustion technology, so as to solve the problem that the direct jet flow in the prior art is difficult to make the gas in the furnace more fully mixed and the temperature distribution More uniform, lower NO _X generation problem.

The technical scheme adopted by the utility model to solve the technical problems is: to provide a concentric axial swirl burner of industrial furnace high-temperature air combustion technology, which consists of a central circular straight pipe, an outer casing, a rotating channel, and a spiral rib. Composed of sheets, the central circular straight-through pipe is located coaxially inside the outer casing.

The rotation angle of the high-temperature air inlet and outlet of the rotating channel varies from 90 degrees to 360 degrees.

The said rotating channel consists of 2-4 spiral fins along the axial direction according to the spiral angle of 90° to 360° and 1 to 3 dimensionless spiral extension lengths R (R=l/h, l is the axial direction of the spiral fins. Length, h is the height of the spiral fin) is rotated and arranged between the central circular straight-through pipe and the outer casing.

Beneficial effect

The utility model can strengthen the sufficient mixing of gaseous fuel and high-temperature air in the hearth of the industrial furnace, thereby ensuring stable combustion at a lower inlet air oxygen concentration, making the temperature distribution in the chamber more uniform, reducing local high temperature, and at the same time The emission of nitrogen oxides (NO _x ) is greatly reduced, and the goals of energy saving and environmental protection are achieved.

Description of drawings

Figure 1 is a front view of a concentric axial swirl burner;

Figure 2 is a schematic diagram of the air intake of a concentric axial swirl burner;

Fig. 3 is a schematic diagram of the structure of the axial spiral fins.

Detailed ways

Below in conjunction with specific embodiment, further set forth the utility model. It should be understood that these embodiments are only used to illustrate the present utility model and are not intended to limit the scope of the present utility model. In addition, it should be understood that after reading the content taught by the utility model, those skilled in the art can make various changes or modifications to the utility model, and these equivalent forms also fall within the scope defined by the appended claims of the application.

Example 1

A concentric axial swirl burner with high temperature air combustion technology for industrial furnaces. It consists of a central circular straight-through pipe 1, an outer casing 2, a rotating channel 3, and spiral fins 4. The central circular straight-through pipe 1 is located on the outer Coaxial position inside layer casing 2. The rotation angle of the high-temperature air inlet and outlet of the rotating channel 3 varies from 90 degrees to 360 degrees. The rotating channel 3 consists of 2-4 spiral fins 4 axially according to the spiral angle of 90 degrees to 360 degrees and 1 to 3 dimensionless spiral extension lengths R (R=l/h, l is the axial length of the spiral fins , h is the height of the helical fin) rotated and arranged between the central circular straight-through pipe 1 and the outer casing 2 .

When the swirl angle of the air swirling channel is 0° (straight jet flow), the inlet parameters are: the fuel is city natural gas, the jet velocity of the central circular tube is 29.5m/s; the jet velocity of the air swirling channel is 35.6m/s. The preheated air is 1273K, the excess air coefficient is 1.2, the oxygen concentration in the air is 8%, and the heat dissipation at the bottom of the furnace is a constant heat flux density of 28580W/m ² .

After the high-temperature air combustion of the industrial furnace, the average temperature of the combustion chamber is: 1556K, the final NO _X emission concentration is 38.2ppm, and the average CO and O ₂ concentrations in the combustion chamber are: 80.6ppm and 1.98%, respectively.

Example 2

When the swirl angle of the air swirling channel is 180°, the inlet parameters are: the fuel is city natural gas, the jet velocity of the central circular tube is 29.5m/s; the jet velocity of the air swirling channel is 35.6m/s. The preheated air is 1273K, the excess air coefficient is 1.2, the oxygen concentration in the air is 8%, and the heat dissipation at the bottom of the furnace is a constant heat flux density of 28580W/m ² .

After the high-temperature air of the industrial furnace is burned, the average temperature of the combustion chamber is 1577K, the final NO _X emission concentration is 34.3ppm, and the average CO and O ₂ concentrations in the combustion chamber are 30.4ppm and 1.31%, respectively.

Example 3

When the swirl angle of the air swirling channel is 210°, the inlet parameters are: the fuel is city natural gas, the jet velocity of the central circular tube is 29.5m/s; the jet velocity of the air swirling channel is 35.6m/s. The preheated air is 1273K, the excess air coefficient is 1.2, the oxygen concentration in the air is 8%, and the heat dissipation at the bottom of the furnace is a constant heat flux density of 28580W/m ² .

After the high-temperature air of the industrial furnace is burned, the average temperature of the combustion chamber is 1584K, the final NO _X emission concentration is 34.1ppm, and the average CO and O ₂ concentrations in the combustion chamber are 28.6ppm and 1.29%, respectively.

Comparing Examples 1 and 2, 3 as can be known, when adopting the swirl type burner, under the same condition, the average temperature in the combustion chamber increases, the final emission of NOx reduces, and the degree of burnout of the fuel (in terms of CO Concentration characterization) increased, and the results show that the swirl burner can significantly improve the performance of industrial furnaces using high-temperature air combustion technology.

Claims (3)

1. the axial turbulent burner of concentric type of an industrial furnace high-temperature air burning technology, by central circular straight pipe (1), outer layer sleeve (2), rotating channel (3), spiral fin (4) is formed, and it is characterized in that: described central circular straight pipe (1) is positioned at the inner coaxial position of outer layer sleeve (2).

2. the axial turbulent burner of concentric type of a kind of industrial furnace high-temperature air burning technology according to claim 1 is characterized in that: the high temperature air import of described rotating channel (3) and the anglec of rotation of outlet are 90 to spend to 360 degree and change.

3. the axial turbulent burner of concentric type of a kind of industrial furnace high-temperature air burning technology according to claim 1 and 2, it is characterized in that: described rotating channel (3) is spent to 360 degree spiral angle and 1～3 zero dimension spiral spread length R by 90 vertically by 2-4 bar spiral fin (4), R=l/h, l is the axial length of spiral fin, h is the spiral fin height, and rotating channel (3) rotation is arranged between central circular straight pipe (1) and the outer layer sleeve (2).

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