A multi-stage swirl ultra-low nitrogen gas burner with flue gas internal circulation

Abstract

The invention discloses a multi-stage swirl ultra-low nitrogen gas burner with internal circulation of flue gas, wherein a central wind area is formed between a central wind tube and a central gas fuel spray gun, and a first swirl wind area and a second swirl wind area are formed between the central wind tube and a swirl-jet wind tube, wherein the first swirl wind area and the second swirl wind area are both annular structures, and the first swirl wind area and the second swirl wind area are sequentially distributed from the inside to the outside, and an annular jet smoke mixed wind area is formed between the swirl-jet wind tube and an outer tube of the burner, and a main gas pipeline is provided on the side of the outer tube of the burner; the gun head of the central gas fuel spray gun passes through the central wind area, the gun head of the middle layer gas fuel spray gun passes through the first swirl wind area, and the gun head of the outer layer gas main fuel spray gun passes through the second swirl wind area; the burner adopts a flue gas recirculation technology, has stable combustion, and has the characteristics of high combustion efficiency and low nitrogen oxide emission.

Description

Technical Field

[0001] The invention belongs to the technical field of clean low-nitrogen combustion of fuel gas, and relates to a multi-stage swirl ultra-low-nitrogen fuel gas burner comprising internal circulation of flue gas. Background Art

[0002] Nitrogen oxides are one of the main air pollutants and the main culprit for PM2.5. During the combustion of combustible gases, nitrogen in the combustion air will generate a large amount of nitrogen oxides (NO x ). As the country's environmental protection efforts continue to increase, many provinces and cities in China have successively introduced more stringent air pollutant emission standards, requiring industrial gas boilers to have NO x The emission concentration control standard is reduced to 30mg / m 3 (Standard state, 3.5% O2, the same below) The existing gas burners are difficult to meet the latest emission requirements, and the development of new ultra-low nitrogen gas burners is imperative.

[0003] The mainstream nitrogen reduction technologies currently used by low-nitrogen burners are staged combustion and swirl combustion technologies. Staged combustion technology is mainly divided into air staged combustion and fuel staged combustion, which is to divide the combustion air or fuel gas into two or three parts and send them to different combustion areas for combustion reaction. In essence, it is through artificial organization that the combustion process is carried out separately under the condition of deviation from the chemical equivalent ratio, effectively avoiding the generation of local high temperature areas and achieving partial NO x Reduction, thereby reducing NO x The swirl combustion technology uses a structure to make the air or gas swirl, so that the fuel and air are mixed violently. The resulting recirculation zone will also suck in some hot flue gas and heat the unburned mixed gas. The flame is kept stable and the generation of local high-temperature areas is reduced. Flue gas recirculation technology is generally used in conjunction with a burner and can be divided into external flue gas circulation and internal flue gas circulation. The principle is to mix the tail flue gas after combustion with the combustion-supporting air and then participate in the combustion again. After the high-temperature flue gas is mixed with the combustion-supporting air, on the one hand, the air temperature is increased, and on the other hand, the oxygen concentration participating in the combustion is reduced, thereby reducing NO in the combustion process. x However, the flue gas external circulation technology has problems such as condensed water corroding equipment and making the combustion in the furnace unstable.

[0004] Judging from the current application situation, the application of a single combustion technology is difficult to meet the latest environmental protection requirements. Some technologies that can significantly reduce nitrogen oxides still face many difficulties in practical application, while most of the technologies that are widely used in practice have a relatively small reduction in nitrogen oxides. The combination of multiple low-nitrogen combustion technologies is the main method to effectively control the generation of nitrogen oxides. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a multi-stage swirl ultra-low nitrogen gas burner including internal flue gas circulation. The burner adopts flue gas recirculation technology, has stable combustion, and has the characteristics of high combustion efficiency and low nitrogen oxide emissions.

[0006] To achieve the above-mentioned object, the multi-stage swirl ultra-low nitrogen gas burner with flue gas internal circulation described in the present invention comprises a central air cylinder, a swirl plate, a swirl disk, a swirl-jet air cylinder, a burner outer cylinder, a central gas fuel spray gun, an intermediate layer gas fuel spray gun, an outer layer gas main fuel spray gun and a main gas pipeline;

[0007] The central wind tube, the swirl plate, the swirl disk, the swirl-jet wind tube and the burner outer tube are arranged in sequence from the inside to the outside, wherein a central wind area is formed between the central wind tube and the central gas fuel spray gun, and a first swirl wind area and a second swirl wind area are formed between the central wind tube and the swirl-jet wind tube, wherein the first swirl wind area and the second swirl wind area are both annular structures, and the first swirl wind area and the second swirl wind area are distributed in sequence from the inside to the outside, and an annular jet smoke mixed air area is formed between the swirl-jet wind tube and the burner outer tube, and a main gas pipeline is provided on the side of the burner outer tube;

[0008] The gun head of the central gas fuel spray gun passes through the central wind area, the gun head of the middle layer gas fuel spray gun passes through the first swirl wind area, and the gun head of the outer layer gas main fuel spray gun passes through the second swirl wind area. A gas fuel annular manifold is provided on the inner side of the burner outer tube. The gas fuel annular manifold is connected to the inlet of the central gas fuel spray gun, the inlet of the middle layer gas fuel spray gun and the inlet of the outer layer gas main fuel spray gun. The main gas pipeline is connected to the central gas fuel spray gun and the middle layer gas fuel spray gun.

[0009] The gun head of the central gas fuel spray gun is tilted at an angle of 5°-85° along the circumferential direction to spray fuel back.

[0010] The gun head of the outer gas main fuel spray gun sprays fuel outwardly in a circular manner at an angle of 5°-85° along the circumferential direction, and sprays fuel outwardly in the axial direction at the same time.

[0011] A flue gas suction groove is provided on the side of the burner outer tube near the burner throat.

[0012] The outlet of the burner outer tube and the outlet of the swirl-jet air duct are both first shrink ring structures bent inwardly by 10°-60°, wherein the bending angles of the first shrink ring structure on the burner outer tube and the first shrink ring structure on the swirl-jet air duct are the same.

[0013] The inlet of the swirl-jet air cylinder is a second shrink ring structure that is bent inwardly by 10°-60°, wherein the length of the second shrink ring structure is adjustable.

[0014] The present invention has the following beneficial effects:

[0015] During the specific operation of the multi-stage swirl ultra-low nitrogen gas burner with internal flue gas circulation described in the present invention, the combustion-supporting gas is sprayed out in four stages through the central wind tube, the swirl wind area of ​​the swirl plate, the swirl wind area of ​​the swirl disk and the jet smoke mixed wind area, and the fuel is mixed with the combustion-supporting gas in three stages through the central gas fuel spray gun, the middle layer gas fuel spray gun and the outer layer gas main fuel spray gun to achieve graded and uniform mixing. At the same time, the fuel sprayed back obliquely downward by the gun head of the central gas fuel spray gun cooperates with the central wind to ensure the stability of the flame; the fuel sprayed by the middle layer gas fuel spray gun cooperates with the swirl wind of the swirl plate to form a central gas fuel spray gun. The fuel sprayed axially from the outer gas main fuel spray gun cooperates with the swirl disk swirl wind to form a main combustion area downstream of the burner throat. The fuel sprayed in the surrounding rings not only participates in the combustion of the intermediate swirl flame diffusion zone, but also mixes with the outer layer of inert flue gas obliquely to form an outer layer of inert mixing zone, thereby achieving further fuel grading. The outer layer of annular jet smoke mixed wind is sprayed obliquely into the main combustion area, which reduces the oxygen content of the combustible mixture in the main combustion area and makes the combustible mixture fully burn out, thereby reducing the overall nitrogen oxide emissions and improving the combustion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present invention;

[0017] Figure 2 is a side view of the present invention;

[0018] Figure 3 It is a schematic structural diagram of the outer layer gas main fuel spray gun 7 in the present invention.

[0019] Among them, 1 is the central gas fuel spray gun, 2 is the central wind tube, 3 is the central wind area, 4 is the middle layer gas fuel spray gun, 5 is the swirl plate, 6 is the swirl plate swirl wind area, 7 is the outer layer gas main fuel spray gun, 8 is the swirl disk, 9 is the swirl disk swirl wind area, 10 is the swirl-jet wind tube, 11 is the jet smoke mixed wind area, 12 is the burner outer tube, 13 is the gas fuel annular header, 14 is the smoke suction groove, 15 is the first shrink ring structure, 16 is the second shrink ring structure, and 17 is the main gas pipeline. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0021] refer to Figures 1 to 3The multi-stage swirl ultra-low nitrogen gas burner with flue gas internal circulation described in the present invention comprises a central wind tube 2, a swirl plate 5, a swirl disk 8, a swirl-jet wind tube 10, a burner outer tube 12, a central gas fuel spray gun 1, an intermediate layer gas fuel spray gun 4, an outer layer gas main fuel spray gun 7 and a main gas pipeline 17; the central wind tube 2, the swirl plate 5, the swirl disk 8, the swirl-jet wind tube 10 and the burner outer tube 12 are arranged in sequence from the inside to the outside, wherein a central wind area 3 is formed between the central wind tube 2 and the central gas fuel spray gun 1, and a first swirl wind area 6 and a second swirl wind area 9 are formed between the central wind tube 2 and the swirl-jet wind tube 10, wherein the first swirl wind area 6 and the second swirl wind area 9 are both annular structures, and the first swirl wind area 6 and the second swirl wind area 9 are annular structures. The two swirl wind areas 9 are distributed in sequence from the inside to the outside, and an annular jet smoke mixed wind area 11 is formed between the swirl-jet wind tube 10 and the burner outer tube 12. A main gas pipeline 17 is provided on the side of the burner outer tube 12; the gun head of the central gas fuel spray gun 1 passes through the central wind area 3, the gun head of the middle layer gas fuel spray gun 4 passes through the first swirl wind area 6, and the gun head of the outer layer gas main fuel spray gun 7 passes through the second swirl wind area 9. A gas fuel annular manifold 13 is provided on the inner side of the burner outer tube 12. The gas fuel annular manifold 13 is connected to the inlet of the central gas fuel spray gun 1, the inlet of the middle layer gas fuel spray gun 4 and the inlet of the outer layer gas main fuel spray gun 7, and the main gas pipeline 17 is connected to the central gas fuel spray gun 1 and the middle layer gas fuel spray gun 4.

[0022] The gun head of the central gas fuel spray gun 1 sprays fuel back at an angle of 5°-85° along the circumferential direction; the gun head of the outer gas main fuel spray gun 7 sprays fuel outward in a circular manner at an angle of 5°-85° along the circumferential direction, and at the same time sprays fuel outward in the axial direction.

[0023] A flue gas suction groove 14 is provided on the side of the burner outer tube 12 near the burner throat; the outlet of the burner outer tube 12 and the outlet of the swirl-jet air duct 10 are both provided with a first shrinking ring structure 15 bent inwardly by 10°-60°, wherein the bending angles of the first shrinking ring structure 15 on the burner outer tube 12 and the first shrinking ring structure 15 on the swirl-jet air duct 10 are the same; the inlet of the swirl-jet air duct 10 is provided with a second shrinking ring structure 16 bent inwardly by 10°-60°, wherein the length of the second shrinking ring structure 16 can be adjusted.

[0024] The present invention achieves super mixing of combustible mixture and internal circulation of flue gas and inert mixing of flue gas and combustible gas through multi-stage graded swirl of gas fuel and combustion-supporting gas, thereby achieving the purpose of reducing the overall nitrogen oxide emission concentration. In actual operation, the present invention provides an economically feasible environmentally friendly transformation technology route for flue gas denitration of gas boilers such as steam boilers, hot water boilers and heating furnaces. Without adding denitration equipment, the nitrogen oxide emission concentration of gas boilers can be reduced to 50mg / m by the burner alone.3 By adding flue gas recirculation technology measures, the nitrogen oxide emission concentration of gas boilers can be reduced to 30mg / m 3 The following meet the latest environmental standards.

Claims

1. A multi-stage swirl ultra-low nitrogen gas burner with flue gas internal circulation, characterized in that: It comprises a central air cylinder (2), a swirl plate (5), a swirl disk (8), a swirl-jet air cylinder (10), a burner outer cylinder (12), a central gas fuel spray gun (1), an intermediate gas fuel spray gun (4), an outer gas main fuel spray gun (7) and a main gas pipeline (17); The central wind tube (2), the swirl plate (5), the swirl disk (8), the swirl-jet wind tube (10) and the burner outer tube (12) are arranged in sequence from the inside to the outside, wherein a central wind area (3) is formed between the central wind tube (2) and the central gas fuel spray gun (1), and a first swirl wind area (6) and a second swirl wind area (9) are formed between the central wind tube (2) and the swirl-jet wind tube (10), wherein the first swirl wind area (6) and the second swirl wind area (9) are both annular structures, and the first swirl wind area (6) and the second swirl wind area (9) are distributed in sequence from the inside to the outside, and an annular jet smoke mixed air area (11) is formed between the swirl-jet wind tube (10) and the burner outer tube (12), and a main gas pipeline (17) is provided on the side of the burner outer tube (12); The gun head of the central gas fuel spray gun (1) passes through the central wind area (3), the gun head of the intermediate gas fuel spray gun (4) passes through the first swirl wind area (6), and the gun head of the outer gas main fuel spray gun (7) passes through the second swirl wind area (9). A gas fuel annular header (13) is provided on the inner side of the burner outer tube (12). The gas fuel annular header (13) is connected to the inlet of the central gas fuel spray gun (1), the inlet of the intermediate gas fuel spray gun (4) and the inlet of the outer gas main fuel spray gun (7). The main gas pipeline (17) is connected to the central gas fuel spray gun (1) and the intermediate gas fuel spray gun (4). The tip of the central gas fuel spray gun (1) is tilted at an angle of 5° to 85° along the circumferential direction to spray fuel back; The gun head of the outer gas main fuel spray gun (7) sprays fuel outward in a circular manner at an angle of 5°-85° along the circumferential direction, and sprays fuel outward in the axial direction at the same time; A flue gas inhalation groove (14) is provided on the side of the burner outer cylinder (12) near the burner throat; The outlet of the burner outer tube (12) and the outlet of the swirl-jet air tube (10) are both first shrink ring structures (15) that are bent inwards by 10°-60°, wherein the bending angles of the first shrink ring structure (15) on the burner outer tube (12) and the first shrink ring structure (15) on the swirl-jet air tube (10) are the same.

2. The multi-stage swirl ultra-low nitrogen gas burner with flue gas internal circulation according to claim 1 is characterized in that: The inlet of the swirl-jet air cylinder (10) is a second shrink ring structure (16) that is bent inwards by 10°-60°, wherein the length of the second shrink ring structure (16) is adjustable.

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