A low nitrogen combustion device and combustion boiler

Abstract

The present invention discloses a low-nitrogen combustion device and a combustion boiler, belonging to the technical field of low-nitrogen combustion components, including a main air duct, one end of which is provided with an air outlet, a central gas pipe is provided therein, the central gas pipe is coaxial with the main air duct, and a flame stabilizing mechanism is provided on the central gas pipe; the central air duct is sleeved on the central gas pipe and is located outside the air outlet, the flame stabilizing mechanism is located in the inner cavity of the central air duct, and one end of the central gas pipe provided with a gas outlet extends out of the central air duct; a plurality of gas spray guns are provided, the plurality of gas spray guns are arranged around the central air duct, and in the axial direction of the main air duct, the distance between the gas nozzle of the gas spray gun and the end face of the end of the main air duct provided with the air outlet is greater than the distance between the flame stabilizing mechanism and the end face on the side away from the gas outlet. The combustion of the gas starts outside the air outlet, no flame is generated in the inner cavity of the main air duct, the heat of the gas combustion can be promptly dissipated into the furnace, the peak temperature of the flame is reduced, and the generation of thermal NOx is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of low-nitrogen combustion components, and in particular to a low-nitrogen combustion device and a combustion boiler. Background Art

[0002] With the advancement of social science and technology and the enhancement of people's environmental awareness, the problem of environmental pollution caused by exhaust gas emitted by industrial gas boilers has received increasing attention. In recent years, the industry has reached a consensus on the positive technical effect of introducing flue gas recirculation technology in the combustion system of high calorific value industrial gas boilers, which can not only reduce the high temperature peak of the combustion area, but also reduce the oxygen content of the gas in the combustion area, thereby effectively reducing the amount of thermal and fuel NOx generated. In addition, the combination of low-nitrogen burners and flue gas external circulation technology is generally used, which can basically reduce the NOx emission of gas boilers to 30mg / Nm 3 The flue gas external circulation technology is achieved by extracting part of the flue gas from the low-temperature section of the flue at the tail end of the boiler and returning it to the burner throat to mix with the combustion air. Since the temperature and oxygen content of the returned flue gas are relatively low, it can effectively reduce the oxygen content and combustion temperature in the combustion-supporting gas after mixing with the combustion-supporting air, thereby inhibiting the generation of NOx.

[0003] The stable combustion performance of low-nitrogen burners and the emission concentration of NOx depend on the structure of the burner. The flame stabilizing devices and gas guns of low-nitrogen burners on the market are mostly set in the throat of the burner. The heat released by the combustion of gas is concentrated in the throat. The heat cannot be released in time, nor can it be released into the furnace by radiation heat release. Therefore, it will lead to the formation of local high-temperature points that are prone to NOx, which increases the generation of NOx. Summary of the invention

[0004] The object of the present invention is to provide a low-nitrogen combustion device and a combustion boiler to solve the problem that the heat in the low-nitrogen combustion device in the prior art is concentrated in the throat cavity and cannot be released in time, resulting in the formation of local high-temperature points that are prone to produce NOx, thereby increasing the amount of NOx generated.

[0005] As conceived above, the technical solution adopted by the present invention is:

[0006] A low nitrogen combustion device, comprising:

[0007] A main air duct, one end of which is provided with an air outlet, a central gas pipe is arranged inside the main air duct, the central gas pipe is coaxial with the main air duct, and a flame stabilizing mechanism is arranged on the central gas pipe;

[0008] A central air duct is sleeved on the central gas pipe and is located outside the air outlet. The flame stabilizing mechanism is located in the inner cavity of the central air duct. One end of the central gas pipe provided with a gas outlet extends out of the central air duct.

[0009] There are multiple gas spray guns, which are arranged around the central wind tube, and in the axial direction of the main wind tube, the distance between the gas nozzle of the gas spray gun and the end face of one end of the main wind tube where the air outlet is arranged is greater than the distance between the side of the flame stabilizing mechanism away from the gas outlet and the end face.

[0010] Furthermore, a plurality of the gas spray guns are arranged in the main air duct; or

[0011] A plurality of gas spray guns are arranged outside the main air cylinder.

[0012] Furthermore, along the radial direction of the central air cylinder, the gas spray guns are arranged in multiple layers, and each layer includes a plurality of the gas spray guns arranged around the central air cylinder.

[0013] Furthermore, the multiple gas spray guns in each layer are located on the same circumferential surface, and the multiple gas spray guns are evenly distributed on the circumferential surface.

[0014] Furthermore, the central air cylinder is a frustum-shaped cylinder, and a preset angle α is formed between the extension direction of the frustum-shaped cylinder and the axial direction of the central gas pipe, 0°<α<90°.

[0015] Furthermore, along the flow direction of the gas flow, the inner diameter of the frustum-shaped cylinder gradually increases.

[0016] Furthermore, one end of the main air duct provided with the air outlet is provided with a bent edge bent toward the inside of the main air duct.

[0017] To achieve the above object, the present invention also provides a combustion boiler, comprising the low-nitrogen combustion device described above.

[0018] Furthermore, the main air duct is fixed to the furnace wall of the combustion boiler through a casting layer.

[0019] The beneficial effects of the present invention are:

[0020] The low-nitrogen combustion device proposed in the present invention arranges the gas port of the central gas pipe, the central air duct, the flame stabilizing mechanism and the gas nozzle of the gas spray gun outside the air outlet of the main air duct, and the flame stabilizing mechanism is arranged in the central air duct. The combustion of the gas starts outside the air outlet of the main air duct, and no flame is generated in the inner cavity of the main air duct. The heat of the gas combustion can be dissipated into the furnace in time, thereby reducing the peak temperature of the flame and reducing the production of thermal NOx. In addition, the flow area of ​​the combustion air flowing to the air outlet of the main air duct and the outer wall of the central air duct close to the main air duct is greatly reduced, and the flow rate of the combustion air is increased. Therefore, when the combustion air flows into this area at a high speed, a negative pressure is formed to generate a sufficiently large suction force, so that the high-temperature flue gas in the furnace flows back to the air outlet of the main air duct, and the combustion air and the high-temperature flue gas are mixed in the area between the main air duct and the outer wall of the central air duct to form a low-oxygen mixed gas. The low-oxygen mixed gas flows out through the inner cavity of the central air duct and is ignited by the central flame. Subsequently, it is burned with a low oxygen content and a concentrated and lean combustion with the gas ejected from the gas nozzle. The low-oxygen mixed gas reduces the probability of the combination of fuel-type nitrogen-containing compounds and oxygen during the combustion process, and also reduces the combustion temperature, thereby reducing the generation of NOx.

[0021] The combustion boiler proposed in the present invention has the above-mentioned low-nitrogen combustion device, which can reduce the generation of NOx and lower the emission of NOx. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the low nitrogen combustion device provided by the present invention;

[0023] Figure 2 yes Figure 1 Side view along direction A;

[0024] Figure 3 It is a schematic diagram of the working state of the low nitrogen combustion device provided by the present invention.

[0025] In the figure:

[0026] 1. Main air duct; 11. Bending edge; 2. Central gas pipe; 3. Flame stabilizing mechanism; 4. Central air duct; 5. Gas spray gun; 51. Gas nozzle; 6. Casting layer;

[0027] 10. Combustion-supporting air channel; 20. Central gas channel. DETAILED DESCRIPTION

[0028] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the present invention are further described below in conjunction with the accompanying drawings and through specific implementation methods. It is understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for the convenience of description, only the parts related to the present invention are shown in the accompanying drawings, not all.

[0029] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0031] In the description of this embodiment, the terms "upper", "lower", "right", etc., directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0032] like Figures 1 to 3 As shown, this embodiment provides a low-nitrogen combustion device, which includes a main air duct 1 for conveying combustion-supporting air, a gas spray gun 5 for conveying fuel gas, a central gas pipe 2 and a central air duct 4 sleeved on the central gas pipe 2.

[0033] Specifically, the inner cavity of the main air cylinder 1 forms a combustion-supporting air passage 10, one end of the main air cylinder 1 is provided with an air outlet, the central gas pipe 2 is provided in the main air cylinder 1, and one end of the central gas pipe 2 provided with a gas outlet extends out of the air outlet of the main air cylinder 1. It can be understood that the end of the main air cylinder 1 provided with an air outlet, that is, the end extending into the boiler is defined as the first end, and the end of the central gas pipe 2 provided with a gas outlet is closer to the furnace center of the boiler than the first end of the main air cylinder 1. In this embodiment, in order to improve the stability of combustion, the central gas pipe 2 and the main air cylinder 1 are coaxial.

[0034] The central wind tube 3 is located outside the air outlet of the main wind tube 1. The central gas pipe 2 is also provided with a flame stabilizing mechanism 3, which is located in the inner cavity of the central wind tube 4. One end of the central gas pipe 2 provided with a gas outlet extends out of the central wind tube 4. There are multiple gas spray guns 5, which are arranged around the central wind tube 4. In the axial direction of the main wind tube 1, the distance between the gas nozzle 51 of the gas spray gun 5 and the end face of the first end of the main wind tube 1 is greater than the distance between the side of the flame stabilizing mechanism 3 away from the gas outlet and the end face of the first end of the main wind tube 1. Specifically, in this embodiment, the multiple gas spray guns 5 are all located in the main wind tube 1. Of course, in other embodiments, the multiple gas spray guns 5 can also be arranged outside the main wind tube 1.

[0035] Understandable, such as Figure 1 As shown, along the axis of the main air duct 1 and in the direction close to the furnace center of the boiler, the air outlet of the main air duct 1, the end of the central air duct 4 close to the main air duct 1, the flame stabilizing mechanism 3, the end of the central air duct 4 away from the main air duct 1 and the gas outlet of the central gas pipe 2 are arranged in sequence, and the gas nozzle 51 of the gas spray gun 5 is located between the gas outlet and the side of the flame stabilizing mechanism 3 away from the gas outlet, or the gas nozzle 51 is closer to the furnace center than the gas outlet. Specifically, in this embodiment, the gas nozzle 51 of the gas spray gun 5 is located between the gas outlet and the side of the flame stabilizing mechanism 3 away from the gas outlet. The gas transported in the central gas channel 20 of the central gas pipe 2 is ignited by the ignition gun after being sprayed out through the gas outlet to form a central flame. The flame stabilizing mechanism 3 is located upstream of the central flame, which can protect the central flame from the influence of a large amount of upstream combustion-supporting air flow, stabilize the central flame, and make the low-nitrogen burner have a good stable combustion ability.

[0036] like Figure 3As shown, by setting a central wind duct 4, the central wind duct 4 is located outside the air outlet of the main wind duct 1, and the flame stabilizing mechanism 3 is arranged in the central wind duct 4, the flow area of ​​the combustion air flowing to the area between the first end of the main wind duct 1 and the outer wall of the central wind duct 4 is greatly reduced, and the flow rate of the combustion air is increased. The gas nozzle 51 of the gas spray gun 5 is located on the outside of the central wind tube 4 and downstream of the flame stabilizing mechanism 3 away from the gas outlet. There is no gas sprayed in the area between the outer walls of the main wind tube 1 and the central wind tube 4 on the left side of the flame stabilizing mechanism 3 away from the gas outlet. Therefore, when the combustion air flows at high speed to the area between the outer walls of the main wind tube 1 and the central wind tube 4, a negative pressure is formed to generate a sufficiently large suction force, so that the high-temperature flue gas in the furnace flows back to the air outlet of the main wind tube 1. The combustion air and the high-temperature flue gas are mixed in the area between the outer walls of the main wind tube 1 and the central wind tube 4 to form a low-oxygen mixed gas. The low-oxygen mixed gas flows out through the inner cavity of the central wind tube 4 and is ignited by the central flame. Then, it is burned with low oxygen and burned in a concentrated and diluted manner with the gas sprayed from the gas nozzle 51. The low-oxygen mixed gas reduces the probability of combining fuel-type nitrogen-containing compounds and oxygen during combustion, and also reduces the combustion temperature, thereby reducing the generation of NOx.

[0037] In addition, the combustion of the gas starts outside the air outlet of the main air duct 1. No flame is generated in the inner cavity of the main air duct 1. The heat of the gas combustion can be dissipated to the furnace in time, which reduces the peak temperature of the flame, reduces the production of thermal NOx, and further reduces the generation of NOx.

[0038] Furthermore, in this embodiment, the central air duct 4 is a frustum-shaped cylinder, and the inner diameter of the frustum-shaped cylinder gradually increases along the flow direction of the gas flow, that is, the large diameter end of the frustum-shaped cylinder is closer to the furnace center of the boiler than the small diameter end of the frustum-shaped cylinder. In this embodiment, the extension direction of the frustum-shaped cylinder forms a preset angle α with the axial direction of the central gas pipe 2, and α is greater than 0° and less than 90°. Of course, in other embodiments, the central air duct 4 can also be a cylindrical cylinder.

[0039] Furthermore, along the radial direction of the central gas pipe 2, the gas spray guns 5 are arranged in multiple layers, each layer includes multiple gas spray guns 5 arranged around the central wind tube 4, and the multiple gas spray guns 5 in each layer are located on the same circumferential surface, and the multiple gas spray guns 5 are evenly distributed on the circumferential surface. Specifically, Figure 2 As shown, in this embodiment, only one layer of gas spray guns 5 is provided, including ten gas spray guns 5 , and the included angles of two adjacent gas spray guns 5 are the same, that is, 36°.

[0040] Furthermore, the flame stabilizing mechanism 3 is a structure such as a swirl disk and a flame stabilizing plate. Of course, the structure of the flame stabilizing mechanism 3 in this embodiment is not limited to this. The flame stabilizing mechanism 3 can also include a disc-shaped body, on which a plurality of ventilation holes are opened, and the outer peripheral surface of the disc-shaped body is provided with an annular flange, and in the axial direction of the disc-shaped body, the angle between the annular flange and the disc-shaped body is greater than 0° and less than or equal to 90°.

[0041] Furthermore, the air outlet of the main air duct 1 is also provided with a bent edge 11 bent inwardly of the main air duct 1. By providing the bent edge 11, the area of ​​the air outlet cross-section of the air outlet can be reduced, and the flow speed of the combustion air can be accelerated, thereby further increasing the flow speed of the combustion air flowing between the first end of the main air duct 1 and the outer wall of the central air duct 4, enhancing the mixing degree of the high-temperature flue gas and the combustion air in the furnace, which is beneficial to reducing the generation of NOx.

[0042] In summary, the low-nitrogen combustion device provided in this embodiment greatly reduces the flow area of ​​the combustion-supporting air flowing to the area between the first end of the main wind tube 1 and the outer wall of the central wind tube 4 close to the main wind tube 1, thereby increasing the flow rate of the combustion-supporting air. Therefore, when the combustion-supporting air flows into the area at a high speed, a negative pressure is formed, thereby generating a sufficiently large suction force. , so that the high-temperature flue gas in the furnace flows back to the air outlet of the main air duct 1, and the combustion-supporting air and the high-temperature flue gas are mixed in the area between the main air duct 1 and the outer wall of the central air duct 4 to form a low-oxygen mixed gas. The low-oxygen mixed gas flows out through the inner cavity of the central air duct 4, is ignited by the central flame, and then is burned with low oxygen and concentrated and lean combustion with the gas sprayed from the gas nozzle 51. The low-oxygen mixed gas reduces the probability of combining fuel-type nitrogen-containing compounds and oxygen during the combustion process, and also reduces the combustion temperature, thereby reducing the generation of NOx.

[0043] In addition, the combustion of the gas starts outside the air outlet of the main air duct 1. No flame is generated in the inner cavity of the main air duct 1. The heat of the gas combustion can be dissipated to the furnace in time, which reduces the peak temperature of the flame, reduces the production of thermal NOx, and further reduces the generation of NOx.

[0044] This embodiment also provides a combustion boiler, which has the above-mentioned low-nitrogen combustion device, and the main air duct 1 of the low-nitrogen combustion device is fixed to the furnace wall of the combustion boiler through the casting layer 6. When the gas spray gun 5 of the low-nitrogen combustion device is located outside the main air duct 1, the gas spray gun 5 and the main air duct 1 are both fixed to the furnace wall of the combustion boiler through the casting layer 6.

[0045] The above embodiments are only to illustrate the basic principles and characteristics of the present invention. The present invention is not limited by the above embodiments. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and modifications, which are within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A low nitrogen combustion device, characterized in that: include: A main air duct (1) is provided with an air outlet at one end, a central gas pipe (2) is provided inside the main air duct, the central gas pipe (2) is coaxial with the main air duct (1), and a flame stabilizing mechanism (3) is provided on the central gas pipe (2); A central air duct (4) is sleeved on the central gas pipe (2) and is located outside the air outlet; the flame stabilizing mechanism (3) is located in the inner cavity of the central air duct (4); and one end of the central gas pipe (2) provided with a gas outlet protrudes from the central air duct (4); A plurality of gas spray guns (5) are provided, wherein the plurality of gas spray guns (5) are arranged around the central wind tube (4), and in the axial direction of the main wind tube (1), the distance between the gas spray head (51) of the gas spray gun (5) and the end surface of the main wind tube (1) at one end of which the air outlet is provided is greater than the distance between the flame stabilizing mechanism (3) on a side facing away from the gas outlet and the end surface; A plurality of gas spray guns (5) are arranged outside the main air cylinder (1); The gas spray guns (5) are arranged in multiple layers along the radial direction of the central wind tube (4), and each layer includes a plurality of gas spray guns (5) arranged around the central wind tube (4).

2. The low nitrogen combustion device according to claim 1, characterized in that: The plurality of gas spray guns (5) in each layer are located on the same circumferential surface, and the plurality of gas spray guns (5) are evenly distributed on the circumferential surface.

3. The low nitrogen combustion device according to claim 1, characterized in that: The central air cylinder (4) is a frustum-shaped cylinder, and a preset angle α is formed between the extension direction of the frustum-shaped cylinder and the axial direction of the central gas pipe (2), 0°<α<90°.

4. The low nitrogen combustion device according to claim 3, characterized in that: Along the flow direction of the gas flow, the inner diameter of the frustum-shaped cylinder gradually increases.

5. The low nitrogen combustion device according to claim 1, characterized in that: One end of the main air duct (1) provided with an air outlet is provided with a bent edge (11) bent inwardly of the main air duct (1).

6. A combustion boiler, characterized in that: It comprises a low nitrogen combustion device as described in any one of claims 1 to 5.

7. The combustion boiler according to claim 6, characterized in that: The main air duct (1) is fixed to the furnace wall of the combustion boiler via a casting layer (6).

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