Natural gas low-nitrogen combustor based on staged combustion and rotational flow combustion

Abstract

The utility model discloses a low-nitrogen combustor, and particularly relates to a natural gas low-nitrogen combustor based on staged combustion and rotational flow combustion. The system comprises a combustor shell, a central gas pipe, an air separation barrel, a central stationary blade grid, a secondary gas main pipe, a secondary gas branch pipe, a secondary stationary blade grid, grid pieces, a gas pipe sealing cover and gas spraying holes. The staged natural gas burner is divided into a first-stage burner and a second-stage burner, multi-stage flames are formed through the staged design, fuel gas concentrated in a burning area is dispersed, excessive heat loads are prevented from being concentrated in a high-temperature area, the local burning temperature is reduced, and the purpose of reducing emission of nitric oxide is achieved. In addition, by means of the structure, mixing of air and fuel gas can be enhanced, rotational flow fuel gas drives a central fuel gas mixture to rotate, the rotational flow degree is enhanced, the mixing degree of the air and the central fuel gas is improved, flame combustion is stable, flame distribution is more uniform, and therefore the combustion efficiency of the combustor is improved.

Description

Technical Field

[0001] The utility model relates to the field of burners, in particular to the field of burners for reducing nitrogen oxide emission pollution based on staged combustion and swirl combustion. Background Art

[0002] Due to the high calorific value of natural gas, the nitrogen and oxygen carried in the air required for combustion react at high temperatures to produce nitrogen oxides. Gas burners primarily produce thermal nitrogen oxides, formed by the oxidation of nitrogen in the air at high temperatures. The amount of nitrogen oxides produced increases with increasing temperature. Therefore, reducing nitrogen oxide emissions from natural gas burners and improving combustion efficiency to reduce fuel consumption are crucial. Currently, requirements for burners in heat treatment furnaces are increasing. Well-designed burners can achieve greater energy efficiency and environmental protection. Premixed combustion, a low-nitrogen natural gas combustion technology, poses risks such as flashback explosions and difficulty in control. Staged combustion technology disperses the combustion area of the gas, thereby avoiding heat load concentration and reducing localized combustion temperatures, thereby controlling nitrogen oxide emissions. Swirl combustion technology swirls the air and gas separately, reducing horizontal flow velocities. The outer swirling air envelops the central gas, improving mixing between the two. Therefore, on the basis of achieving low emissions, the design of a low-nitrogen burner structure based on staged combustion and swirl combustion technology is particularly important for low-nitrogen combustion and reducing pollutant emissions.

[0003] The utility model discloses a natural gas low-nitrogen burner based on staged combustion and swirl combustion. The utility model can not only achieve the purpose of reducing nitrogen oxide emissions, but also increase the degree of mixing between gas and air through swirl, and make the flame distribution more uniform, thereby increasing the combustion efficiency of the burner. Summary of the Invention

[0004] The purpose of this utility model is to provide a natural gas low-nitrogen burner for a heat treatment furnace based on staged combustion and swirl combustion to address the above-mentioned problems, which can improve the combustion efficiency of the fuel and reduce the emission of nitrogen oxides.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solutions: a natural gas low-nitrogen burner for a heat treatment furnace based on staged combustion and swirl combustion, comprising a burner casing, a central gas pipe, an air separation cylinder, a secondary gas main pipe, a secondary gas branch pipe, a secondary static blade grid, a central static blade grid, a grid sheet, a gas pipe cover, and an injection hole. The vertical pipe portion of the central gas pipe is installed in a reserved hole in the burner casing, and the inner side of the burner casing and the outer side of the primary gas pipe constitute an internal air intake channel; a static blade grid is provided at the right end of the central gas pipe, and the air separation cylinder is provided at the outside thereof; a gas pipe cover and evenly distributed circumferential injection holes are provided at the end of the central gas pipe; a secondary gas main pipe is provided at the left end of the air separation cylinder, and secondary gas branches are evenly provided at the right end of the secondary gas main pipe.

[0006] Preferably, the central static blade cascade and the secondary static blade cascade are both composed of two circular rings with a grating sandwiched between them.

[0007] Preferably, the vertical pipe portion of the central gas pipe and the vertical portion of the secondary gas main pipe are respectively connected to the reserved holes in the burner shell, and the inner side of the burner shell and the horizontal pipe portion of the central gas pipe constitute the main air intake channel.

[0008] Preferably, 8 secondary gas pipes are evenly distributed on the secondary burner.

[0009] Preferably, the end of the secondary gas branch pipe sprays gas in a direction deflected 30 degrees from the Y direction to the X direction and 30 degrees from the Z direction to the X direction. Preferably, the grids are evenly arranged at 35 degrees.

[0010] Preferably, the end of the central gas pipe is connected to the gas pipe cover, and the end of the central gas pipe is provided with 6 gas injection holes evenly distributed in the circumferential direction.

[0011] Compared to existing technologies, the present invention offers the following advantages: the staged burner comprises a central gas pipe and a central stator cascade forming a primary burner, an air separator tube located between the two gas pipe stages, and a secondary gas pipe and secondary stator cascade forming a secondary burner. Compared to existing burners, this staged design disperses the high-temperature zone that was previously concentrated in the center, lowering local temperatures and reducing nitrogen oxide emissions. Furthermore, after gas staging, the natural gas ejected from the secondary gas pipe forms a swirling flow, increasing the mixing of gas and air and evenly distributing the flame, thereby increasing the burner's combustion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0013] Figure 1 This is a schematic diagram of the structure of the natural gas burner of the utility model;

[0014] Figure 2 This is a schematic diagram of the three-dimensional structure of the natural gas burner of the utility model;

[0015] Figure 3 This is the right side view of the natural gas burner of the present utility model;

[0016] Figure 4 This is a front view structural diagram of the secondary gas main pipe and the secondary gas branch pipe of the utility model;

[0017] Figure 5 This is a cross-sectional view of the secondary gas branch pipe of the present invention.

[0018] In the figure, 1-burner casing, 2-center gas pipe, 3-air separation cylinder, 4-secondary gas main pipe, 5-secondary gas branch pipe, 6-secondary static blade grid, 7-center static blade grid, 8-gas pipe cover, 9-injection hole, 10-grid plate. DETAILED DESCRIPTION

[0019] This section will specifically describe the embodiments of the utility model. The more ideal embodiments of the utility model are shown in the accompanying drawings. The purpose of the accompanying drawings is mainly to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and implementation method of the utility model, but it cannot be understood as a limitation on the scope of protection of the utility model.

[0020] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0021] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connected," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration. The specific meanings of these terms in this utility model can be reasonably determined by those skilled in the art based on the specific content of the technical solution.

[0022] See also Figure 1-4The utility model provides a solution: a natural gas low-nitrogen burner for a heat treatment furnace based on staged combustion and swirl combustion, wherein the inner side of the burner shell (1) and the outer side of the central gas pipe (2) form an internal air intake channel; the right end of the central gas pipe (2) is provided with the central static blade grid (7), and the outer side of the central static blade grid is provided with an air separation cylinder (3); the end of the central gas pipe (2) is provided with a gas pipe cover (8) and uniformly distributed circumferential injection holes (9); the left end of the air separation cylinder (3) is provided with the secondary gas main pipe (4), and the right end of the secondary gas main pipe (4) is uniformly provided with secondary gas branch pipes (5); the inner end of the burner shell (1) is provided with a secondary static blade grid (6), the vertical pipe part of the central gas pipe (2) and the vertical part of the secondary gas main pipe (4) are respectively connected to the reserved holes of the burner shell (1), and the inner side of the burner shell (1) and the horizontal pipe part of the central gas pipe (2) form a main air intake channel. The central static blade cascade (7) and the secondary static blade cascade (6) are both composed of two circular rings with a grating (10) sandwiched between them, and the grating (10) is evenly arranged at 35 degrees. Eight secondary gas branch pipes (5) are evenly distributed on the secondary gas main pipe (4). The end of the central gas pipe (2) is connected to the gas pipe cover (8), and the end of the central gas pipe (2) is provided with six circumferentially evenly distributed injection holes (9).

[0023] Specifically, air enters from the right end of the burner housing (1), passes through the air separation cylinder (3), and is divided into primary air and secondary air. The primary air and secondary air pass through the central static blade grid (7) and the secondary static blade grid (6), respectively, forming a primary swirl wind, a primary direct wind, a secondary swirl wind, and a secondary swirl wind. Gas enters from the central gas pipe (2) and the secondary gas main (4) inlet respectively. The gas in the central gas pipe (2) is blocked by the gas pipe cover (8), and the gas is ejected from the jet hole (9). The gas in the secondary gas main (4) enters the eight secondary gas branch pipes (5) and is ejected at a certain angle, thereby inducing the formation of secondary swirl gas, driving the central gas to rotate and enhance the swirl degree, thereby enhancing the degree of mixing with the central swirl air and prolonging the combustion time of air and gas. The secondary swirl gas is fully mixed with the primary swirl wind and wraps the central gas-air mixture. After ignition, a swirl flame is formed. The secondary direct wind blows forward to blow away the high-temperature flame area, thereby reducing the temperature of the high-temperature flame area, thereby reducing the thermal NOx content. Because the central mixture flows at a high velocity and experiences large pressure fluctuations, a low-pressure zone is easily formed. The secondary swirl flow is slower and envelops the central direct air, creating a flue gas recirculation zone in the central annular area. Because the recirculated flue gas is at a higher temperature, it provides the necessary energy for ignition of the central gas, thereby improving the stability of the central flame.

[0024] Therefore, it can be seen that this design disperses the gas concentrated in the combustion area, preventing excessive heat load from concentrating in high-temperature areas, lowering local combustion temperatures, and thus reducing nitrogen oxide emissions. Furthermore, this structure enhances the mixing of air and gas. The swirling gas drives the central gas mixture to rotate and increase the swirl, improving the mixing of air and central gas, stabilizing flame combustion and making flame distribution more uniform, thereby increasing the burner's combustion efficiency.

[0025] While the embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to the embodiments described above. Various modifications and improvements may be made to the present invention without departing from the spirit and scope of the present invention, and such modifications and improvements are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A natural gas low-nitrogen burner based on staged combustion and swirl combustion, comprising a burner housing (1), a central gas pipe (2), an air separation cylinder (3), a secondary gas main pipe (4), a secondary gas branch pipe (5), a secondary static blade cascade (6), a central static blade cascade (7), a gas pipe cover (8), an air jet hole (9), and a grid plate (10), characterized in that: The inner side of the burner housing (1) and the outer side of the central gas pipe (2) form an internal air intake channel; the right end of the central gas pipe (2) is provided with the central static blade grid (7), and the outer side of the central static blade grid (7) is provided with an air separation cylinder (3); the end of the central gas pipe (2) is provided with a gas pipe cover (8) and evenly distributed circumferential injection holes (9); the left end of the air separation cylinder (3) is provided with the secondary gas main pipe (4), and the right end of the secondary gas main pipe (4) is evenly provided with secondary gas branch pipes (5); the inner end of the burner housing (1) is provided with a secondary static blade grid (6).

2. A natural gas low-nitrogen burner based on staged combustion and swirl combustion according to claim 1, characterized in that the central static blade cascade (7) and the secondary static blade cascade (6) are both composed of two circular rings with a grid plate (10) sandwiched between them.

3. A natural gas low nitrogen burner based on staged combustion and swirl combustion according to claim 2, characterized in that The grid pieces (10) are evenly arranged at 35 degrees.

4. A natural gas low nitrogen burner based on staged combustion and swirl combustion according to claim 1, characterized in that The vertical pipe portion of the central gas pipe (2) and the vertical portion of the secondary gas main pipe (4) are respectively connected to the reserved holes of the burner shell (1), and the inner side of the burner shell (1) and the outer side of the horizontal pipe of the central gas pipe (2) form a main air intake channel.

5. The natural gas low nitrogen burner based on staged combustion and swirl combustion according to claim 1 is characterized in that Eight secondary gas branch pipes (5) are evenly distributed on the secondary gas main pipe (4).

6. A natural gas low nitrogen burner based on staged combustion and swirl combustion according to claim 5, characterized in that The end of the secondary gas branch pipe (5) sprays gas in a direction deflected 30 degrees in the Y direction toward the X direction and in a direction deflected 30 degrees in the Z direction toward the X direction.

7. The natural gas low nitrogen burner based on staged combustion and swirl combustion according to claim 1 is characterized in that The end of the central gas pipe (2) is connected to the gas pipe cover (8), and the end of the central gas pipe (2) is provided with six circumferentially evenly distributed gas injection holes (9).

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