KR100400418B1 - Oxygen enriched combustion burner for low NOx emission - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burner for reducing the generation of nitrogen oxides in an oxygen enriched combustion in which oxygen is combusted by combustion with combustion air. A central air nozzle 34 is installed at the center of the center, and a plurality of outer air nozzles 35 and a plurality of outer fuel nozzles 33 are alternately installed on the outer concentric circles of the central air nozzle 34 to cross each other. It is arranged so as to be arranged, or are respectively set to be biased, the flame is uniformly divided, the complete combustion is induced by two-stage combustion, the gas suction rate in the furnace is increased, the generation of unburned dust is not only prevented, but also nitrogen There is an effect that the generation of oxide is significantly reduced.

Description

Oxygen enriched combustion burner for low NOx emission

The present invention is a burner for reducing the generation of nitrogen oxides in the oxygen-enriched combustion in which oxygen is mixed with combustion air to combust, more specifically, the secondary air is supplied from the center of the burner and the fuel and For low nitrogen oxide burners supplying primary air.

In general, oxygen-enriched combustion generates a large amount of nitrogen oxides (NOx) due to the high temperature of combustion, but the practical application is very limited despite the high thermal efficiency.

That is, the generation of NOx increases in proportion to the combustion temperature, but 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, thereby generating a large amount of NOx.

In order to extremely reduce the amount of NOx generated in the oxygen-enriched combustion, the oxygen concentration in the combustion air must be lowered by maximizing the amount of intake of gas in the furnace in the combustion air. That is, the temperature rise near the burner discharge port should be suppressed by the suction of the gas in the furnace, and the flame retardant mechanism is necessary to suppress the generation of unburned dust and to stabilize the flame.

In particular, the suction rate of the gas in the furnace is affected by factors such as the number of air and fuel nozzles, the shape and size of the nozzle, the injection speed, and the injection position.

As a factor influencing the suction rate of the gas in the furnace, the suction rate increases when the nozzle size is large, and as the number of fuel nozzles increases, the flame is divided, which is advantageous for complete combustion, and the surface area of the flame increases, thereby facilitating heat transfer.

If the number of air nozzles is large, the suction rate can be increased.If the combustion air is divided into primary and secondary air, the NOx generation can be reduced by the effect of multi-stage combustion, and the fuel nozzle and the air nozzle are related to the arrangement of the nozzles. As the distance increases, combustion is delayed and NOx is reduced, but unburned dust is generated.

Therefore, it is necessary to optimize the influence factors in order to maximize the suction rate of the gas in the furnace and reduce the amount of NOx generated while achieving complete combustion.

Conventionally, a burner using a high-speed air injection method based on two stages of air combustion has been the most representative of many methods for reducing NOx in oxygen-enriched combustion.

The burner using such a high-speed injection method reduces the oxygen concentration in the combustion air by sucking a large amount of combustion gas in the furnace as air (oxygen) is injected at a high speed, and delays combustion near the burner discharge port, thereby reducing the amount of NOx generated. In recent years, a lot of researches have been made as a method of reducing NOx of high temperature combustion, and typical burners include the following first and second burners.

First, the conventional first burner described in US Pat. No. 4,378,205 (1983) or the like used an air high-speed injection method, and as shown in side cross-sectional and front views of the conventional first burner of FIGS. 1A and 1B, A fuel nozzle 13 provided at the center, a primary air nozzle 14 annularly formed on the outer periphery of the fuel nozzle 13, and a fuel nozzle 13 and a primary air nozzle 14 provided on the outer circumferential concentric circles It consists of a plurality of secondary air nozzles 15.

The conventional first burner configured as described above injects primary and secondary air at high speed and sucks combustion gas in the furnace during air classification, thereby diluting the oxygen concentration in the combustion air before the air reacts with the fuel, NOx is reduced by lowering the oxygen concentration.

Next, the conventional second burner described in Japanese Patent Laid-Open No. 7-103428 (1995) is air installed at the center of the burner 21, as shown in side cross-sectional and front views of the conventional second burner of FIGS. 2A and 2B. It consists of a nozzle 23 and a plurality of fuel nozzles 3 provided on the outer circumferential concentric circle of the air nozzle 23.

In the conventional second burner configured as described above, air is injected at a high speed in the center of the burner 21 to be mixed with gas in the furnace, and then mixed with fuel to combust to delay combustion time between fuel and air to reduce NOx. do.

However, in the conventional first burner, the amount of NOx generated was variable according to the number of secondary air nozzles 15, the position from the center of the burner 11 of the secondary air nozzles 15, and the injection speed of air. Under some conditions, there was a problem in that a large amount of flame injury or unburnt (CO) was generated under some conditions.

In addition, when the secondary air nozzle 15 is close to the fuel nozzle 13, there is no problem of fine dust, but the amount of NOx is generated. As the secondary air nozzle 15 moves away from the fuel nozzle 13, the amount of NOx is generated. Was decreased but the flame was unstable and the amount of unburned smoke was increased.

In the conventional second burner, the air is injected only from one air nozzle 23, so that the mixing performance with the gas inside the furnace is lowered, and the NOx generation characteristic depends on the distance between the air nozzle 23 and the fuel nozzle 24. This is changed, there was a problem that the occurrence of unburned.

On the other hand, the conventional first burner has a minimum NOx generation amount of 300 ppm or more, and the conventional second burner also has a NOx generation amount of 200 ppm and the NOx generation amount does not satisfy the pollution standard, and thus there is a practical problem.

The present invention has been invented to solve the problems in the prior art as described above, the combustion air is divided into a central air nozzle and a plurality of outer air nozzles installed in the center of the nozzle and injected, and the fuel and the outer air nozzle It is an object of the present invention to provide a low nitrogen oxide oxygen enriched combustion burner that minimizes NOx generation by maximizing the suction rate of gas in the furnace while injecting a plurality of fuel nozzles installed on the same circumference.

Side sectional and front views of a conventional first burner of FIGS. 1A and 1B.

Side sectional and front views of a conventional second burner of FIGS. 2A and 2B.

3A and 3B are side cross-sectional and front views of an oxygen-enriched combustion burner according to the present invention.

3c is a front view of another oxygen enriched combustion burner according to the present invention;

<Description of the symbols for the main parts of the drawings>

31: Burner 32: Burner Tile

33: Outer fuel nozzle 34: Center air nozzle

35: outer air nozzle

In the low nitrogen oxide oxygen enriched combustion burner of the present invention for achieving the above object, in the oxygen enriched combustion burner having a fuel nozzle and a plurality of air nozzles, a central air nozzle 34 is formed at the center of the burner 31. And a plurality of outer circumferential air nozzles 35 and a plurality of outer circumferential fuel nozzles 33 are alternately installed on the outer circumferential concentric circles of the central air nozzle 34 so as to intersect with each other.

In the present invention, in the oxygen-enriched combustion burner having a fuel nozzle and a plurality of air nozzles, a central air nozzle 34 is provided at the center of the burner 31, and the central air nozzle 34 has an outer circumferential concentric shape. A plurality of outer air nozzles 35 and a plurality of outer fuel nozzles 33 are biased and installed in each.

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

3A and 3B are side cross-sectional and front views of an oxygen-enriched combustion burner according to the present invention, and FIG. 3C is a front view of another oxygen-enriched combustion burner according to the present invention, in which 31 is a burner, 32 is a burner tile, and 33 is an outer periphery. The fuel nozzle, 34 is a central air nozzle, and 35 is an outer air nozzle.

In the present invention, as shown in FIG. 3A, a central air nozzle 34 is installed at the center of the burner 31, and the plurality of outer fuel nozzles 33 and the outer circumference are arranged on the concentric circles of the outer air nozzle 34. An air nozzle 35 is installed.

In addition, according to the exemplary embodiment of the present invention, the outer air nozzle 35 and the outer fuel nozzle 33 may be alternately arranged as shown in FIG. 3B.

In addition, according to another embodiment of the present invention, the outer air nozzle 35 and the outer fuel nozzle 33 may be arranged to be biased to a portion of the outer circumference, as shown in Figure 3c.

Meanwhile, as shown in FIG. 3A, all of the outer fuel nozzle 33 and the outer air nozzle 35 are installed in parallel with the central axis of the burner 31, but the present invention is not limited thereto and the outer fuel nozzle 33 is not limited thereto. ) And all or part of the outer air nozzle 35 may be formed to be inclined with the central axis of the burner 31.

In addition, as shown in Figure 3b and 3c, the outer fuel nozzle 33, the central air nozzle 34 and the outer air nozzle 35 is shown in a circular shape, the present invention is not limited to this, but also in a polygonal structure It may be formed.

Hereinafter will be described in detail the operation of the present invention configured as described above.

First, the air is divided into the central air nozzle 34 and the outer air nozzle 35 to be injected to achieve two-stage combustion of the air.

That is, when the outer fuel nozzle 33 and the outer air nozzle 35 are alternately arranged as shown in FIG. 3B, the air injected from the outer air nozzle 35 reacts with the fuel first to serve as primary air. And, the air injected from the central air nozzle 34 serves as secondary air.

3C, when the outer fuel nozzle 33 and the outer air nozzle 35 are arranged in a biased manner, the air injected from the central air nozzle 34 serves as the primary air and the outer air nozzle. Air injected at 35 serves as secondary air.

Therefore, when the nozzle is arranged as described above, the effect of the two-stage combustion can be basically obtained, so that the amount of NOx generated can be reduced as compared with the case of the one-stage combustion of the conventional second burner of FIG.

In the burner according to the present invention, since the fuel is injected through the plurality of outer fuel nozzles 33 on the same circumference as the outer air nozzle 35, the flame is divided, so that the fuel is burned in the burner 11 like the conventional first burner. The reaction time with the air is delayed than when sprayed from the center, so that no local hot spots occur in the flame.

In addition, the air nozzle is divided into the central air nozzle 34 and the outer air nozzle 35, so that the suction rate of the gas in the furnace can be increased than in the case where the air nozzle is only in the center as in the conventional second burner.

On the other hand, LPG is used as a fuel for the first and second burners and the burners according to the present invention, and the combustion capacity is 100,000 kcal / hr, the air ratio is 1.1, the furnace temperature is 1,300 ° C, and the oxygen concentration in the air is in the range of 30 to 50%. As a result, the burner according to the present invention can burn low nitrogen oxides of less than 100ppm in all combustion conditions, and complete combustion is possible without generating unburned carbon monoxide. It was possible.

As described in detail above, using the low nitrogen oxide oxygen enriched combustion burner of the present invention has the following effects.

First, the flame is divided by injecting fuel from a plurality of outer fuel nozzles based on the central injection of air by the central air nozzle to uniformly raise the temperature of the heating object.

Second, by injecting air by the outer air nozzles arranged on the same circumference as the outer fuel nozzles, the two-stage combustion and the intake rate of the gas into the air are increased.

Third, by installing the outer fuel nozzle and the outer air nozzle adjacent to each other, it is possible to prevent air pollution by minimizing the generation of nitrogen oxides while preventing the generation of unburnt by the gentle mixing and flame action of fuel and air. .

Fourth, in addition to oxygen-enriched combustion, the same principle can be applied to high temperature combustion such as heat storage combustion using high temperature air.

Claims (2)

In an oxygen-enriched combustion burner having a fuel nozzle and a plurality of air nozzles, a central air nozzle 34 is provided at the center of the burner 31, and a plurality of outer air is formed on the outer circumferential concentric circle of the central air nozzle 34. Low nitrogen oxide oxygen enriched combustion burner, characterized in that the nozzle 35 and a plurality of outer fuel nozzles (33) are alternately installed so as to cross each other. In an oxygen-enriched combustion burner having a fuel nozzle and a plurality of air nozzles, a central air nozzle 34 is provided at the center of the burner 31, and a plurality of outer air is formed on the outer circumferential concentric circle of the central air nozzle 34. Low nitrogen oxide oxygen enriched combustion burner, characterized in that the nozzle 35 and the plurality of outer peripheral fuel nozzles (33) are installed in a biased manner.