KR200213935Y1 - A low NOx burner Equipped With polygonal nozzles - Google Patents

Abstract

The present invention relates to a structure of a burner for reducing the generation of nitrogen oxides generated in high-temperature combustion, such as oxygen-enriched combustion that mixes oxygen with combustion air and burns the combustion air at high temperature.

To this end, the present invention is a two-stage combustion burner in which a secondary air nozzle 27 is formed on a concentric circle on the fuel nozzle 24, the primary air nozzle 26, and the burner tile 25 at the center of the burner 22. A low nitrogen oxide burner having a polygonal nozzle comprising a plurality of polygonal nozzles forming a secondary air nozzle (27), and the primary air nozzle (26) or fuel nozzle (24) is also optionally composed of polygonal nozzles. to provide.

According to the present invention, the polygonal nozzle having a relatively long outer circumference is used as the fuel nozzle and the air nozzle to increase the intake rate of the gas into the air stream, thereby suppressing the amount of nitrogen oxides generated at high temperature combustion. It is effective.

Description

Low NOx burner Equipped With polygonal nozzles

The present invention relates to a structure of a burner for suppressing nitrogen oxides generated from high temperature combustion such as oxygen enrichment combustion for mixing oxygen with combustion air for combustion and regenerative combustion for preheating the combustion air at high temperature. The secondary air nozzle is composed of a plurality of polygonal nozzles, and the primary air nozzle or fuel nozzle is selectively composed of polygons, so that the suction rate of the gas inside the air stream can be increased, thereby reducing the generation of nitrogen oxides. It relates to a low nitrogen oxide burner having a.

In general, in combustion equipment such as metal heating furnaces and other industrial furnaces, in order to increase combustion efficiency, a combustion method such as oxygen-enriched combustion that mixes oxygen with combustion air and burns it, or regenerative combustion that preheats the combustion air at a high temperature. Is used.

However, although the combustion method has high thermal efficiency, the practical application is very limited because of the generation of excessive nitrogen oxide (NOx) due to the high temperature of the combustion temperature.

In general, the generation of nitrogen oxides increases in proportion to the combustion temperature. In the case of oxygen-enriched combustion, the amount of combustion gas per unit calorie is small and the combustion temperature is inversely proportional to the amount of combustion gas per unit calorie. Nitrogen oxides are generated. In addition, in regenerative combustion, since the combustion air of high temperature (above 800C) is used, the combustion temperature is increased and the amount of nitrogen oxides is increased.

Therefore, in order to reduce the generation of nitrogen oxides at high temperature combustion, such as conventional oxygen enriched combustion or regenerative combustion, many methods have been proposed in recent years, and the most representative one is the air high speed injection method based on air two stage combustion. In this method, as shown in Japanese Patent Application Laid-Open No. 6-257723 and US Pat. No. 4,378,205, a plurality of air nozzles are disposed on the outer concentric circle of a fuel nozzle installed at the center of the burner, and oxygen or oxygen-enriched air is disposed. By spraying at a higher speed than normal combustion, nitrogen oxides are reduced.

Similarly, Japanese Patent Application Laid-Open No. Hei 7-103428 installs a high-speed injection oxygen nozzle at the center of a burner and injects fuel through a plurality of nozzles on the outer concentric circle of the oxygen nozzle. In this type of burner, as the air (oxygen) is injected at high speed, the combustion gas in the furnace is sucked to lower the combustion temperature near the burner discharge port and the oxygen concentration in the combustion air. Much research has been done as a method of suppressing nitrogen oxides in combustion.

However, this method has a problem in that it is practically applicable as the amount of the lowest nitrogen oxides generated is 200 PPM or more.

FIG. 1A shows a representative structure of a conventional high-speed injection type low nitrogen oxide burner. The fuel nozzle 24 is formed at the center of the burner 22, and the fuel nozzle is formed at the burner tile 25 at the tip of the burner 22. As shown in FIG. An annular primary air nozzle 26 is provided on the outer periphery of (24). Further, a plurality of secondary air nozzles 27 are provided on the outer circumferential concentric circles of the fuel nozzle 24 and the primary air nozzle 26. FIG. 1B shows the structure of the fuel nozzle 24 and the primary and secondary air nozzles 26 and 27 formed on the burner tile 25 in a side view.

In the burner having such a configuration, combustion is carried out before the air reacts with the fuel by sucking the combustion gas in the furnace during the air classification which flows into the burner 22 and is injected at high speed into the primary and secondary air nozzles 26 and 27. The oxygen concentration in the air is diluted to reduce the nitrogen oxides by lowering the combustion temperature and lowering the oxygen concentration.

However, the burner having the above structure has a variable amount of nitrogen oxide depending on the number of secondary air nozzles, the position of the nozzle away from the center of the burner, and the air injection speed. Accordingly, there was a problem in that a large amount of flame injury or unburned (CO) is generated. That is, when the secondary air nozzles are close to the fuel nozzles, there is no problem of fine combustion (CO), but the generation amount of nitrogen oxides increases, and as the secondary air nozzles move away from the fuel nozzles, Although the amount of generation is reduced, there is a problem that the flame is unstable and the amount of unburned smoke is increased.

On the other hand, Figures 2a to 2b is a burner devised by the inventors to solve the problems of the conventional burner shown in Figure 1 (Korean Patent Application No. 10-1999-0061646), the secondary air small nozzle 31 and air hole nozzle By dividing by (32) and spraying at high speed, it is possible to minimize the combustion of low nitrogen oxides and the generation of unburned dust. The burner with the above structure shows a relatively satisfactory nitrogen oxide reduction performance, but it is necessary to further suppress the generation of nitrogen oxide in order to preserve the environment, so that stable combustion and complete combustion are possible to expand the application of high temperature combustion technology in the future. Low nitrogen oxide combustion technology is required.

The present invention has been made to solve the above problems, the object of the present invention is to make the secondary air nozzle is composed of a plurality of polygonal nozzles, in order to suppress the nitrogen oxide generated in the high-temperature combustion, primary air nozzle or fuel nozzle It is to provide a low nitrogen oxide burner having a polygonal nozzle selectively composed of the polygon.

Figure 1a is a cross-sectional view showing a schematic structure of a conventional low nitrogen oxide burner

Figure 1b is a side view showing the structure of the burner tile according to the prior art

Figure 2a is a cross-sectional view showing a schematic structure of another conventional low nitrogen oxide burner

Figure 2b is a side view showing the structure of a burner tile composed of a conventional small hole nozzle and a porous nozzle

Figure 3 is a side view showing the structure of a burner tile consisting of a polygonal nozzle as various embodiments according to the present invention

Explanation of symbols for the main parts of the drawings

22: burner 24: fuel nozzle

25: burner tile 26: primary air nozzle

27: secondary air nozzle 31: small air nozzle

32: anti-air nozzle

The present invention is configured as follows to achieve the above object. That is, the present invention is a two-stage combustion burner in which a fuel nozzle, a primary air nozzle, and a secondary air nozzle are formed on a concentric circle on the burner tile, and a plurality of polygonal nozzles form a secondary air nozzle. The primary air nozzle or the fuel nozzle is also characterized in that it is optionally composed of a polygonal nozzle.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a view showing that the polygonal nozzle of various forms is provided as an embodiment according to the present invention.

First, the basic structure and arrangement of the burner are the same as those of the first to second drawings. That is, the fuel nozzle 24 is installed at the center of the burner 22, and the annular primary air nozzle 26 is provided on the outer periphery of the fuel nozzle 24 on the burner tile 25 at the tip of the burner 22. . In addition, a plurality of secondary air nozzles 27 are provided on the outer circumferential concentric circles of the fuel nozzle 24 and the primary air nozzle 26. In this case, the plurality of secondary air nozzles 27 located in the burner tile 25 may be formed in a polygon in the shape of the outer circumference constituting the nozzle. In addition, the fuel nozzle 24 and the primary air nozzle 26 also have a polygon in the form of the outer periphery thereof. Further, such polygonal nozzles may be used for the fuel nozzle 24 and the air nozzles 26 and 27 respectively or simultaneously.

In the present invention according to the configuration as described above, in order to reduce the amount of nitrogen oxide generated during the high-speed injection combustion of the burner, the oxygen concentration in the combustion air must be lowered by maximizing the suction amount of the gas inside the combustion air. That is, the temperature rise near the burner discharge port should be suppressed by the suction of the furnace gas, and the suction rate of the furnace gas into the combustion air depends on the number of air nozzles, the nozzle size, the injection speed, and the injection position. It depends. In consideration of the shape of the nozzle, the suction rate increases in proportion to the contact area between the nozzle and the furnace gas. That is, if the injection speeds in the nozzles are the same, the area of the nozzles is the same regardless of the shape of the nozzles, but the length of the nozzle circumference is very variable according to the shape of the nozzles even in the same nozzle area.

On the other hand, when the nozzle area is the same, the circular nozzle has the shortest length of the nozzle circumference (circumference) among all types of nozzles. Therefore, in the case of the secondary air nozzle, the suction rate can be increased by employing the polygonal nozzle instead of the circular nozzle. Done.

For example, a 5 cm diameter circle has an area of 19.63 cm 2 and a circle has a perimeter of 15.7 cm, but a square having the same area as the circle has a diameter of 17.7 cm, and any of the rectangles has the same area of 10 cm and 1.963 cm. The nozzle circumference is 23.93 cm. The equilateral triangle has the same perimeter as 20.19 cm. As such, depending on the type of polygon used, the length of the circumference forming the polygon varies. Therefore, as the outer circumference of the polygonal nozzle increases, the contact area with the gas inside the furnace increases, so that the suction rate increases.

On the other hand, Figure 3 shows a variety of embodiments according to the shape of each nozzle formed in the burner tile 25, in (a) and (b) the secondary air nozzle 27 having a rectangular and trapezoidal shape is annular It may have a structure that is arranged. In addition, as shown in (c) and (d), in the structure having the small hole nozzle 31 and the large hole nozzle 32, the small hole nozzle 31 can be formed in a circular shape, and the large hole nozzle 32 can be formed in a rectangular shape. Or a structure consisting of a rectangle and a triangle. In addition, as shown in (d), the shape of the fuel nozzle 24 and the primary air nozzle 26 can also be configured as a polygon.

In this way, the shape of the polygon forming the nozzle is rectangular (a, c), trapezoid (b), triangle (d), star shape, cross shape, etc., in addition to the circular shape in the secondary air nozzle (27). It can be made, and can be configured in various forms without particular limitation in the form. Further, in addition to the secondary air nozzle 27, for example, the fuel nozzle 24 or the primary air nozzle 26 may be utilized individually or in the form of nozzles of the aforementioned type.

In particular, when the fuel nozzle or the primary air nozzle is composed of polygons, the stability of the flame and the flammability are increased by increasing the mixing of air and the primary air.

<Comparative Example>

Experimental results to explain a comparative example of the prior art and the adoption of the polygonal nozzle of the present invention are as follows.

First, in the experiment, the burner having the nozzle structure of FIG. 1 as the comparative burner was selected, and the present inventors selected a burner that optimized the performance of nitrogen oxide (NOx) through further research. 3 (a) is selected. At this time, the number of secondary air nozzles 27 according to the prior art and the present invention is 8, the size of the nozzle is 9mm in the case of the conventional type mentioned in Figure 1, the nozzle of the present invention is 16mm horizontal, 4 vertical The mutual area (injection rate) is the same in mm. In addition, the outer periphery of each nozzle is 28.3 mm in a circle, and 40 mm in a rectangle.

On the other hand, the distance from the center of the burner 22 to the center of the secondary air nozzle 27 was produced similarly to 100 mm.

First, nitrogen oxide generation was measured when the furnace temperature reached 1,300 ℃ under conditions of 19% oxygen enrichment (40% oxygen concentration in air) and air ratio 1.1 using LPG as a fuel at a combustion capacity of 100,000 kW / hr. In one bar, the conventional burner is 140 PPM, the burner according to the present invention was generated nitrogen oxide of less than 100PPM.

Therefore, according to the present invention employing a polygonal nozzle as shown in the above results, low nitrogen oxide combustion is possible.

According to the present invention having the above structure, by employing a polygonal nozzle having a relatively long outer circumference of the nozzle, it is possible to increase the intake rate of the furnace gas into the air classification, thereby reducing the amount of nitrogen oxide generated during combustion.

Claims (1)

Two-stage combustion type formed by the primary air nozzle 26 and the secondary air nozzle 27 installed on the fuel nozzle 24 and the burner tile 25 on the outer periphery of the fuel nozzle 24 at the center of the burner 22. In the burner, a plurality of polygonal nozzles form the secondary air nozzles 27, and the primary air nozzles 26 or the fuel nozzles 24 are also optionally constituted by polygonal nozzles. Low nitrogen oxide burners.