KR960002791B1 - Burner - Google Patents

Abstract

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Description

Low NOX Burner

1 is a cross-sectional view of a low NO _x burner implementing the method of the present invention.

FIG. 2 is a cross-sectional view taken along the line “II-II” of FIG. 1.

3 is a front view of a stabilizer viewed in the direction of arrow "III" of FIG.

4 is a cross-sectional view in the direction of arrow "IV" of FIG.

5 is a combustion state according to the present invention.

6 is a view of the combustion salt in the left direction of FIG.

7 is an explanatory diagram of a known flue gas recirculation method.

8 is an explanatory diagram of a known combustion gas self-circulation method.

9 and 10 are explanatory views of a known two-stage combustion system.

11 to 13 are explanatory views of a known split flame method.

* Explanation of symbols for main parts of the drawings

1: blower 2: window box

3: damper 4: nozzle chamber

5: stabilizer 6: brazier

7: oil pump 8: oil pipe

9: nozzle 10: outer cylinder

11: inner cylinder 12: front wall

13: room 14: air port

16: circulating gas inlet 17: Induce nozzle

18: ignition transformer 19: ignition electrode

20 gas outlet

[Industrial use]

The present invention relates to a low NOx burner that suppresses NOx that causes air pollution.

[Prior art]

The NOx suppression combustion technology in the burner is known as (a) exhaust gas recirculation, (b) two stage combustion and (c) split flame type catalytic combustion.

The exhaust gas recirculation method of (a) is a method of recycling the exhaust gas in the recirculation passage (b) branched from the year (a) as shown in FIG.

This method has the following advantages and disadvantages.

(1) It is said that the most effective and reliable NOx suppression technology is when the recycle gas temperature is low around 300 ℃.

On the other hand, the combustion gas self-circulation method as shown by the symbol (c) of FIG. 8 has a low NOx suppression effect and a low oxygen partial pressure because the temperature of the circulating gas is high at 1000-1500 ° C. Combustion becomes unstable.

The combustion gas self-recirculation method is simple, but the effect of the current technology cannot be expected very much.

(2) The exhaust gas recirculation method mixes the flue gas (O ₂ = 3-5%) with the new combustion air (O ₂ = 21%) and around 20 of the flue gas with respect to air (O ₂ = 18- 19%), and it is necessary to increase the combustion chamber volume (10-16%).

(3) The flue gas recirculation method has a large facility area and is relatively expensive for heat facilities of 100 × 10 ⁴ Kcal / h or less.

Next, the two-stage combustion system (see FIGS. 9 and 10) of (b) has the following problems.

(1) The first stage oxidized flame combustion and the second stage reduced salt combustion as shown in FIG. 10 can be performed with gas or oil burner of 100 × 10 ⁴ Kcal / h or more, but with oil burner of 100 × 10 ⁴ Kcal / h or less The space of the combustion port part becomes large and it is not practical.

(2) The first stage of reduced salt combustion and the second stage of oxidative salt combustion as shown in Fig. 9 can be performed with a gas burner, but it is easy to generate soot with an oil burner. In addition, if the heat dissipation during the first stage reduction salt combustion is not sufficient, the NOx suppression is not performed because the flame temperature is shifted to the second stage oxidation combustion without lowering.

(3) The two-stage combustion method can be designed freely with burner mouths, so it is relatively easy to install as a large burner with a mounting surface space, but the small burner has a limited size of the combustion port and a small mounting space. The case is a problem.

(4) If a plurality of oil nozzles are installed, they can be mounted on the same plane, but mounting on the front and rear shafts in the direction of combustion is unreasonable and may cause trouble.

In addition, the split flame method of (c) (a concentrated, a fresh burning method) (refer to FIG. 11 thru | or 13) of air rich salt and an oil odor salt as shown in FIG. Combination,

(1) For large oil burners and gas burners, a plurality of nozzles can be used to make a split flame relatively freely. However, a dry-type burner has a burner flame opening of 100 × 10 ⁴ Kcal / h or less with a diameter of 165 mm or more. In the design, there is a difficulty in making a split flame (concentrated, fresh burning) (Fig. 13) by mounting a plurality of nozzles and changing the amount of combustion individually.

[Problem to Solve Invention]

The low NOx burner according to the present invention combines a split flame method and a self-recirculation method to provide a novel supply method of combustion air and recycle gas for forming a split flame, and the flame temperature is higher than 1300 ° C. Iii) Shape (partially divided) oxidized salt is a part of the combustion zone, which allows the generation of NOx to be slightly suppressed, and the reduced oxide combustion zone for reducing NO is close to the shaped oxide zone, which is the NO generating section It is an object of the present invention to provide a low NOx burner capable of minimizing NOx generation since it has a function of reducing and denitrifying the NOx produced by the diffusion of the gas stream again.

[Means for solving the problem]

Combustion air is divided into two stages, the first stage is combusted in a reducing atmosphere, and the second stage air is alternately arranged around the self-recirculating gas and the circumference, and the model oxidative combustion zone and the model reduction combustion zone are alternately supplied. In which the split flame is formed in the ring-shaped reduced combustion air stream so as to be centrifugally spread, and combustion is completed in the shaped oxidized combustion zone, and the remaining air diffuses into the shaped reduced salt combustion zone. Allows slow burning in low conditions. Molded Oxidized Bases, Alternating Formed reduced bases are considered as a bundle of one stream.

The combustor stream gradually loses inertia and slows down to complete the element, but some self circulates from the outer periphery of the flame to the burner's circulating gas intake. In addition, some of them were designed to be a circulating flow flowing into the negative pressure generated in the center of the flame.

EXAMPLE

It demonstrates based on drawing.

In FIG. 1, combustion air enters the window box 2 from the blower 1, a part of which is slowed down by a stabilizer 5 installed at the tip of the nozzle chamber 4 via an adjustable damper 3. It turns into a swirl flow and blows out in the furnace 6.

The oil is boosted by the oil pump 7, passed through the oil pipe 8, sprayed into the fine particles from the nozzle 9, and mixed with the combustion air flow to start combustion. The first stage combustion air amount supplied through the damper 3 forms a reducing atmosphere (acid flare combustion) at 15 to 40% of the total combustion air amount.

The second stage combustion air passes through the gap between the outer cylinder 10 and the inner cylinder 11, and the air is divided into a plurality of parts in the front wall 12 of the indus nozzle 17 and blows out from the chamber 13 toward the air inlet 14. The mixture is mixed with a reducing atmosphere to form a plurality of shaped oxidized combustion zones in the furnace 6 and is burned with blue salts.

A part of the combustion gas is self-circulated while dissipating heat and enters from the circulating gas intake port 16 and is taken out again from the circulating gas outlet 20 into the furnace 6. Numeral 17 denotes an endless nozzle for facilitating circulation of the combustion gas by using the circulating gas suction port 16 as a negative pressure. The ignition transformer 18 sends a high voltage current to the tip of the ignition electrode 19, and ignites the mixed air stream by an electric flame. The outlet 20 of the circulating gas is provided in plural around the circumference (FIG. 2), and is alternately adjacent to the air port 14 and arranged in a ring shape. Therefore, the combustion air stream (O ₂ = 21%) and the circulating gas stream (O ₂ = 2%) are alternately taken out of the shape and surrounded by the reducing atmosphere of the first stage (see "A" in FIG. 5). In the area of mixing with the circulating gas stream in the area of mixing with the circulating combustion air stream, however, the oil particles are spun at high temperatures in the acid flaw state to promote gasification, but do not reach combustion. That is, the flame formed becomes a plurality of shaped split flames as in the sixth degree. Since the air ratio of this modeling oxidized flame is 1.7 or more, and heat radiation of a flame is performed easily and rapidly, since flame temperature does not exceed 1500 degreeC, generation | occurrence | production of NOx can be suppressed.

Conventional split flame type NOx burners are divided into flames with a plurality of oil nozzles, but because of the directionality of the flame, they become rod-shaped flames and are poorly mixed with combustion air, and excess air requires 30% or more. Was doing.

In addition, since combustion occurs at an air ratio (less than 20% of excess air), soot is generated, and thus there is a restriction on low oxygen combustion of the low-NOx burner of the split flame method.

The low NOx burner of the present invention combines a split flame method and a self-recirculation method, and is a burner having an evaporation mechanism of oil particles by ultra-stage combustion, and forms a reducing salt in one oil nozzle first to evaporate spray particles to oil It is a split flame type burner which forms combustion oxide and recirculating gas in the form of a model and forms a flame combustion region of a model by alternately arranging and supplying combustion air and recycle gas to a gaseous reducing atmosphere.

It is a method of reducing NOx, which is called fuel rich and air odor by the split flame method, and is called concentrated and fresh burning. However, the burner of the present invention centrifugally reduces the dense atmosphere by evaporating oil particles in the early stage of the combustion process. Since it diffuses and alternately supplies combustion air and recirculating gas to form a shaped area of combustion oxide and reducing combustion at the combustion flame surface, there is no soot at low air ratio (15% of excess air). The reduction was 60%.

Due to the actual function test by 30,000 Kcal / h hot water boiler, the NOx stage measure burner converted to NOx value 88ppm O ₂ = 0%, and this low NOx burner converted to 32ppm O ₂ = 0%, NOx reduction rate of 64% It has achieved phenomenal results. (The Tokyo standard for low NOx equipment is therefore 80ppm O ₂ = 0%.)

In addition, the burner of the present invention pivotally introduces 15 to 40% of the total amount of combustion air from the nozzle chamber 4 through the stabilizer 5 as the first stage combustion air, and mixes the fine oil particles sprayed from the oil nozzle 9. And ignited to diffuse in the centrifugal direction due to the inertia of the swirling air from the stabilizer 5 which forms the reducing atmosphere. During this time, the heat of combustion is consumed to evaporate and vaporize the oil particles, so the flame temperature does not exceed 1200 ° C. In addition, a plurality of second stage combustion tools 14 and a recirculating gas outlet 20 are provided adjacent to each other.

Combustion air blown out from the air port 14 is mixed and diffused with the first-stage reducing atmosphere gas stream to form a modeled oxidized salt and burns rapidly. The reducing atmosphere gas stream of the first stage which is mixed with the recycle gas taken out from the recycle gas outlet 20 is vaporized by the heat of the recycle gas and the heat from the modeled oxidized salt and becomes a hot gas stream, but combustion can continue due to the acid deficient atmosphere. In the absence of a state, following the modeling oxidized salt, but reaches the end of the combustion of the modeled oxidized salt, it diffuses with the remaining air, and performs a 3rd stage gentle combustion (refer FIG. 6), and combustion is completed.

[effect]

In the combustion method according to the present invention, the combustion air is divided into two stages, and is supplied in the first stage of the reducing atmosphere, and the second stage of the air is divided and alternately arranged to supply with the self-recirculating gas. Oxidation Salt Combustion Zone The modeled reduction salt combustion zone is formed alternately to form a split flame. At the end of the combustion of the modeled oxidized combustion zone, the remaining air diffuses into the reduced salt combustion zone and completes a gentle combustion, but at the end, the annular combustion stream gradually loses inertia and slows down, and some of the outer periphery of the flame It is returned to the burner's circulation inlet and part of it is a circulation flow flowing into the negative pressure portion generated at the center of the flame, thereby contributing to NOx suppression occurring at the center of the flame.

By this combustion method, the flame temperature of more than 1300 ° C is part of the modeled oxidized combustion zone and can slightly suppress the generation of NOx.

In addition, since the shaped reducing salt combustion zone for reducing NO coexists with the forming oxide burning zone for producing NO and has a function of reducing the NOx produced by the diffusion, the generation of NOx can be suppressed to a minimum. .

Claims (1)

The combustion air of the blower 1 is divided into the first stage combustion air and the second stage combustion air from the window box 2, and the first stage combustion air is supplied through the damper 3 to the oil nozzle 9 and the ignition electrode ( 19) enters the nozzle chamber (4) is installed, passes through the stabilizer (5), and blows into the furnace (6) in a slow swirling flow state, so as to form a reducing atmosphere by centrifugal force and inertial action to burn, and the second stage combustion Air is ejected to the place where the indus nozzle 17 is alternately formed between the outer and the inner cylinders 10 and the inner cylinders 11, and is formed in the shape of the reduced atmosphere (partly divided shape). ) The circulating flow of reducing atmosphere is divided into the oxidizing flame combustion zone and the model combustion zone, and the outer periphery of the decelerated flame where the inertia is lost is returned to the circulating gas intake and the reducing atmosphere Low NOx burner characterized in that ever cycle combustion caused by the negative pressure section in the center salt.