CN115143459A - Injection premixing smoke internal circulation low-nitrogen combustor - Google Patents

Abstract

The invention discloses an injecting premixed flue gas internal circulation low-nitrogen burner, which belongs to the technical field of burners. The gas pipes are coaxially arranged, the peripheral air pipe includes an air pipe constriction port installed at the end, and a peripheral gas ring cavity is sleeved downstream of the peripheral air pipe, and the peripheral gas ring The inner wall of the cavity and the hemispherical gas injector, the hemispherical gas injector is installed on the surface of the outer body; the invention strengthens the mixing of air and gas by setting the peripheral air pipe, so that the mixing is more uniform, the combustion efficiency is improved, and the thermal efficiency of the boiler is increased; the main gas is used. The pipes form a staging of air and fuel, creating a multi-stage flame, which reduces the flame temperature and thus greatly reduces the emission of nitrogen oxides.

Description

A low-nitrogen burner with internal circulation of ejected premixed flue gas

technical field

The invention belongs to the technical field of burners, and in particular relates to a low-nitrogen burner that injects premixed flue gas with internal circulation.

Background technique

During the operation of the heating furnace, a large amount of flue gas emissions are generated, among which NOx, CO, etc. bring air pollution, which has a bad impact on the environment and human health, and affects the sustainable development of society. The low NOx technology of the burner , premixed combustion has the risk of tempering explosion, is not easy to control, and is not enough energy-saving; and the external circulation of flue gas also has the factors of unstable flame and increased cost, which is not conducive to the long-term stable operation of the heating furnace. Refer to the patent: Chinese patent CN 214840801 U adopts the outer ring cavity type gas injection, and forms a flue gas injection structure, the peripheral gas and air are partially mixed, this structure is conducive to reducing NOx, but the ability of gas classification is relatively weak, and the flame is concentrated In the middle, it is easy to generate a high temperature area, which leads to the increase of NOx. Therefore, a more reasonable and effective low-NOx burner structure with staging and internal flue gas circulation combustion is still required to organize combustion and control pollutant emissions.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a low-nitrogen burner that injects premixed flue gas internal circulation, and applies the gas classification and flue gas internal circulation combustion technology to the forced blast burner technology, aiming to solve the problem of nitrogen gas in common boiler gas burners. Problems such as high oxide emissions and unstable combustion.

In order to achieve the above purpose, the present invention provides the following technical solutions: a low-nitrogen burner for injecting premixed flue gas internal circulation, including a peripheral air pipe and a main gas pipeline, the peripheral air pipe is sleeved on the outside of the main gas pipeline and Coaxially arranged with the main gas pipeline, the peripheral air pipe includes an air pipe constriction installed at the end, and a peripheral gas ring cavity is sleeved downstream of the peripheral air pipe, and the peripheral gas ring cavity includes an annular cavity inclined side wall , the inner wall of the annular cavity and the hemispherical gas injector, which is installed on the surface of the outer body.

As a preferred embodiment, the inclined side wall of the annular cavity is inclined, and is arranged in parallel with the constriction opening of the air pipe, premixing injection holes perpendicular to the inclined plane are uniformly opened thereon, and the hemispherical gas injector is uniformly opened. There are four gas holes in different directions, namely the peripheral oblique injection gas hole, the inward oblique injection gas hole and two annular oblique injection gas holes in opposite directions.

As a preferred embodiment, the main gas pipeline is sequentially installed with several uniformly installed gas branch pipes and radial injection holes with uniform openings at the ends, the gas branch pipes are connected to the main gas pipeline and the peripheral gas ring cavity, An air divider arranged coaxially is installed between the peripheral air pipe and the main gas pipeline, and a flame stabilization disc is installed at the end of the air divider, and the flame stabilization disc is located between the gas branch pipe and the radial injection hole, The swirl vanes and the expansion port of the flame stabilization disc are arranged on it.

As a preferred embodiment, the number of the swirling blades is 4-10.

As a preferred embodiment, the swirl angle of the swirl vane is 20°˜60°.

As a preferred embodiment, the radial injection holes are 4 to 12.

As a preferred embodiment, the gas ventilation area of the radial injection holes accounts for 5% to 10%.

Compared with the prior art, the beneficial effects of the present invention are:

The low-nitrogen burner injecting premixed flue gas with internal circulation strengthens the mixing of air and gas by setting peripheral air pipes, so as to make the mixing more uniform, improve the combustion efficiency, and increase the thermal efficiency of the boiler; the main gas pipeline is used to form air and fuel grading, forming a multi-stage flame, reducing the flame temperature, thereby greatly reducing the emission of nitrogen oxides; the air pipe constriction through the swirling effect and the mutual shearing and flame transfer between the multi-stage flame areas, so that the mixed gas The combustion is more stable; the peripheral gas ring cavity adopts the flue gas internal circulation and partial premixed combustion technology to further reduce the emission of nitrogen oxides.

Description of drawings

Fig. 1 is the plane structure schematic diagram of the present invention;

Fig. 2 is the side structure schematic diagram in the present invention;

FIG. 3 is a schematic diagram of the internal structure in the present invention.

In the picture: 1- Peripheral air pipe, 2- Main gas pipe, 3- Air pipe shrinkage, 4- Peripheral gas ring cavity, 5- Hemispherical gas injector, 6- Inclined side wall of ring cavity, 7- Premix injection hole , 8-inner wall of annular cavity, 9-air splitter, 10-flame stabilization disk, 11-swirl vane, 12-radial injection hole, 13-gas branch pipe, 14-flame stabilization disk expansion port, 15-outer body, 16- peripheral oblique gas injection hole, 17- annular oblique gas injection hole, 18- inward oblique injection gas hole.

Detailed ways

The present invention will be further described below in conjunction with the embodiments.

The following examples are used to illustrate the present invention, but cannot be used to limit the protection scope of the present invention. Conditions in the examples can be further adjusted according to specific conditions, and simple improvements to the method of the present invention under the premise of the concept of the present invention all belong to the scope of protection of the present invention.

Example 1

1-3, the present invention provides a low-nitrogen burner for injecting premixed flue gas with internal circulation, including a peripheral air pipe 1 and a main gas pipe 2, and the peripheral air pipe 1 is sleeved on the outside of the main gas pipe 2 And coaxially arranged with the main gas pipeline 2, the peripheral air pipe 1 includes an air pipe constriction 3 installed at the end, and a peripheral gas ring cavity 4 is sleeved downstream of the peripheral air pipe 1, and the peripheral gas ring cavity 4 includes the oblique side of the ring cavity. The wall 6, the inner wall 8 of the annular cavity and the hemispherical gas injector 5, the hemispherical gas injector 5 is installed on the surface of the outer body 15, the oblique side wall 6 of the annular cavity is an inclined plane, and is arranged in parallel with the air pipe shrinkage 3, and there are even vertical openings on it. In the premixed injection hole 7 on the inclined plane, the hemispherical gas injector 5 has four gas holes with different directions evenly, namely the peripheral oblique injection gas hole 16, the inward oblique injection gas hole 18 and the two circumferentially opposite directions. The oblique injection gas hole 17, the main gas pipeline 2 is sequentially installed with a number of uniformly installed gas branch pipes 13 and the radial injection holes 12 with uniform holes at the end, the gas branch pipe 13 is connected to the main gas pipeline 2 and the peripheral gas ring cavity 4, A coaxial air divider 9 is installed between the peripheral air pipe 1 and the main gas pipe 2, and a flame stabilization disc 10 is installed at the end of the air divider 9. The flame stabilization disc 10 is located between the gas branch pipe 13 and the radial injection hole 12. The swirl vane 11 and the expansion port 14 of the flame stabilizing plate are set on it, the peripheral air pipe 1 and the air divider 9 are used for the passage of air flowing through, and the air is guided to the boiler furnace, and the main gas pipe 2 is used for the gas to enter The passage of the burner, which guides the gas to the boiler hearth, and the air is divided into two parts after entering the burner. Part of the air passes through the air divider 9 and passes through the swirl vanes 11 of the flame stabilization disc 10 to form primary air, and the other part of the air passes through the passage between the peripheral air pipe 1 and the air divider 9 and flows through the flame stabilization disc to expand The port 14 ejects the burner obliquely outward to form secondary air, and the peripheral air flows through the expansion port 14 of the flame stabilization disk to form an entrainment effect, so that the downstream flue gas flows from the air pipe constriction port 3 and the annular cavity inclined side wall 6. The ejection port formed between the two parts enters the burner again to participate in mixing and combustion. Due to the shrinkage effect of the air pipe constriction port 3, the air flow rate increases to form a negative pressure ejection effect, and the return effect of the flue gas is more obvious. Cooling and inhibiting effects reduce the temperature of the combustion flame and reduce the formation of nitrogen oxides.

When in use, the gas enters the main gas pipeline 2 and is divided into three parts. The first part of the gas is injected radially out through the radial injection holes 12, mixed with part of the primary air, and burned near the central axis of the boiler furnace to form a primary flame In this area, the amount of air in this area is low, resulting in lean oxygen combustion, low combustion temperature, and chemical reduction atmosphere, reducing the generation of NOx, the second part of the gas passes through the gas branch pipe 13 and then enters the peripheral gas ring cavity 4, and then is divided into multiple strands Gas, part of the gas is sprayed from the premixing injection hole 7, mixed with the flue gas injected back into the burner, mixed with air in advance, and then flows through the expansion port 14 of the flame stabilization disc to form a secondary flame area, This area is lean premixed combustion, with low combustion temperature and low NOx generation. In addition, the primary air produces a swirl effect due to the air flowing through the swirl vanes 11. In addition, due to the swirl entrainment effect, the primary flame area and the secondary flame Heat exchange is formed between the secondary flame areas to ensure the stability of combustion. Part of the gas is ejected from the inward oblique gas injection hole 18 obliquely to the central axis, and mixed with part of the secondary air to form a tertiary flame area. This area and The secondary flame areas overlap to form a stable heat exchange atmosphere and flame stabilization structure. Part of the gas is ejected from the annular oblique gas injection holes 17 along the circumference of the peripheral gas ring cavity 4, and mixed with part of the secondary air to form a fourth-level flame In the area, the adjacent annular oblique gas injection holes 17 collide in the direction, so the flame has a hedging characteristic, which makes the mixing more uniform and the flame more stable. Mixed combustion forms a peripheral grading flame. This part of the area has excess air, which is oxygen-enriched combustion. Each combustion area is subjected to swirl action to produce mixing effect and shearing effect, carrying out intense material and heat transfer, forming a stable and efficient. burning area.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims (10)

1. The utility model provides an draw and penetrate low NOx burner of premixed flue gas inner loop, includes peripheral air pipe (1) and main gas pipeline (2), its characterized in that: the outside of main gas pipeline (2) is located to peripheral air pipe (1) cover and with main gas pipeline (2) coaxial arrangement, peripheral air pipe (1) is including installing air pipe constriction opening (3) at the tip, peripheral air pipe (1) low reaches cover is equipped with peripheral gas ring chamber (4), peripheral gas ring chamber (4) are including the oblique lateral wall of ring chamber (6), ring chamber inner wall (8) and hemisphere gas sprayer (5), body (15) surface is installed outside hemisphere gas sprayer (5).

2. The low-nitrogen combustor for injecting premixed flue gas internal circulation according to claim 1, is characterized in that: the inclined side wall (6) of the annular cavity is an inclined plane and is arranged in parallel with the air pipe contraction port (3), a premixing injection hole (7) perpendicular to the inclined plane is uniformly formed in the inclined side wall, four gas holes in different directions are uniformly formed in the hemisphere gas injector (5), and the inclined injection hole is a peripheral inclined injection gas hole (16), an inward inclined injection gas hole (18) and 2 annular inclined injection gas holes (17) in opposite directions.

3. The low-nitrogen combustor for injecting premixed flue gas internal circulation according to claim 1, is characterized in that: a plurality of gas branch pipes (13) which are uniformly installed and radial jet holes (12) which are uniformly perforated at the end parts are sequentially installed on the main gas pipeline (2).

4. The injection premixing flue gas internal circulation low-nitrogen combustor according to claim 3, characterized in that: the gas branch pipe (13) is connected with the main gas pipeline (2) and the peripheral gas ring cavity (4).

5. The low-nitrogen combustor for injecting premixed flue gas internal circulation according to claim 1, is characterized in that: install air shunt (9) of coaxial setting between peripheral air pipe (1) and main gas pipeline (2), steady flame dish (10) are installed to air shunt (9) tip.

6. The low-nitrogen combustor for injecting premixed flue gas internal circulation according to claim 5, is characterized in that: the flame stabilizing disc (10) is positioned between the gas branch pipe (13) and the radial jet hole (12), and is provided with swirl vanes (11) and a flame stabilizing disc expansion opening (14).

7. The low-nitrogen combustor with the function of injecting the premixed flue gas and the internal circulation is characterized in that: the number of the rotational flow blades (11) is 4-10.

8. The low-nitrogen combustor with the function of injecting the premixed flue gas and the internal circulation is characterized in that: the rotational flow angle of the rotational flow blade (11) is 20-60 degrees.

9. The low-nitrogen combustor with the function of injecting the premixed flue gas and the internal circulation is characterized in that: the number of the radial jet holes (12) is 4-12.

10. The low-nitrogen combustor for injecting premixed flue gas internal circulation according to claim 1, is characterized in that: the gas ventilation area of the radial jet holes (12) accounts for 5% -10%.

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