A circular tangential flat flame nozzle and its combined array structure

Abstract

This application discloses a circularly tangential flat flame nozzle and its combined array structure, relating to the field of nozzle structures. It includes a nozzle body with an inlet end and an outlet end at both ends. Gaseous oxidant enters from the inlet end and exits from the outlet end. The inlet end has a circular cross-section, and the projection of the outlet end along the axis of the nozzle body's inlet end is elliptical. The outlet end is arc-shaped, with its axis perpendicular to the plane containing the major axis of the ellipse and the inlet end axis, and the arc axis intersects with the inlet end axis. This provides a sufficiently large scattering area, allowing the process gas and oxidant to mix thoroughly at the nozzle outlet, improving the combustion efficiency of the process gas, and forming a uniform temperature distribution in the reactor combustion chamber.

Description

Technical Field

[0001] The invention relates to a circular tangential flat flame nozzle and its combined arrangement array, which is suitable for the combustion reaction of process gas in various catalytic reactors, especially the second-stage conversion furnace in ammonia synthesis units, and can also be used for preheating furnaces. Background Technology

[0002] Currently, the single-nozzle outlet type of burners used in the second-stage furnace of ammonia synthesis units is mostly trumpet-shaped, circular, or elliptical. The above-mentioned nozzle types have problems such as small scattering area and small temperature gradient in the jet zone, which can easily cause catalyst bed overheating and deactivation. There are stress concentration areas in the nozzle body, which will cause high-temperature creep when exposed to high temperature environment for a long time, affecting the service life of the equipment. Existing burners have unreasonable nozzle distribution, uneven flow field distribution causing dead zones, and flame licking the furnace to avoid burning the furnace bricks, all of which are extremely detrimental to the long-term stable operation of the unit. Summary of the Invention

[0003] The technical problem solved by this application is to overcome the shortcomings of the prior art and provide a circularly shaped flat flame nozzle and its combined array structure. The circularly shaped nozzle outlet design can significantly improve the energy decay rate in the jet zone, reduce the catalyst bed temperature, and extend the catalyst life. At the same time, the circularly shaped outlet design can increase the scattering area, enhance the mixing efficiency, and avoid deformation of the nozzle body caused by local thermal stress. Multiple combined arrays suitable for different furnace types can effectively improve the flow field distribution in the combustion chamber and ensure uniform energy density.

[0004] This patent addresses the design principles of ensuring long-term stable operation of the catalytic converter, reducing furnace shut-off frequency, and preventing catalyst bed sintering, detachment, or high-temperature deactivation. The patent utilizes a circular-cut flat-flame nozzle, installed on a tube-bundle burner or annular burner, enabling long-term operation of the catalytic reactor. Under prolonged high-temperature conditions, the burner itself does not experience severe deformation. The circular-cut nozzle design minimizes thermal stress-induced collapse deformation, ensuring the normal operation of the entire unit. The combined array of nozzles achieves efficient air distribution and organized combustion conversion, resulting in good mixing of the oxidant and process gas. After thorough mixing, combustion is achieved with uniform energy density distribution. The conversion temperature is uniform across the same height section within the furnace, with a relatively low temperature in the core combustion zone, preventing catalyst bed deactivation due to overheating and avoiding catalyst sintering and melting.

[0005] The technical solution provided in this application is as follows:

[0006] In one aspect, a circularly tangent flat flame nozzle is provided, wherein the nozzle inlet cross section is circular, the outlet is circularly tangent, and the outlet projection is elliptical.

[0007] The ratio of the major and minor axes of the ellipse in the export projection is 3 to 5.

[0008] The nozzle opening is deformed from a circle to an elliptical outlet along the axial direction. The inner and outer sides of the nozzle are modified by wire cutting, and then the nozzle outlet is cut with an arc. The arc angle is preferably 100° to 130°.

[0009] The end face of the outlet end is rounded at the edges between the inner and outer walls of the nozzle body, with a radius of R = 0.5 mm to R = 2 mm.

[0010] Secondly, a combined array structure of circular tangent flat flame nozzles is provided, which is usually used in combination with multiple sets of nozzles. For cylindrical or conical combustion chambers, multiple nozzle bodies are distributed in a circumferential array or a radial array; for square combustion chambers, multiple nozzle bodies are distributed in a U-shaped array or a staggered array.

[0011] The circumferential array is generally arranged with 2 to 4 groups of nozzles (including the central nozzle), and each group contains at least 3 nozzles except for the central nozzle.

[0012] The radial array typically consists of 5 to 9 rows of nozzles, with each row containing 3 to 5 nozzles.

[0013] The zigzag array typically consists of 2 to 3 layers of nozzles.

[0014] Staggered arrays typically consist of 3 to 6 rows of nozzles.

[0015] The circular array is distributed with the central nozzle arranged vertically. Except for the central nozzle, each ring of nozzles is evenly distributed in a circle at a certain angle to the vertical direction, and the spray angle spreads outward. The angle of the second ring is 3.5° to 4.5°, the angle of the third ring is 5.5° to 8.0°, and the angle of the fourth ring is 8.5° to 9.5°.

[0016] The radial array has no central nozzle. Each ring of nozzles is evenly distributed in a circle at a certain angle to the vertical direction, with the spray angle spreading outwards. The angle of the first ring is 1.5° to 2.5°, the angle of the second ring is 3.0° to 4.0°, the angle of the third ring is 4.5° to 6.0°, the angle of the fourth ring is 6.5° to 7.5°, and the angle of the fifth ring is 8.0° to 8.5°.

[0017] The zigzag array has two nozzle arrangement methods: one is that adjacent nozzles spray gas in opposite directions at a certain angle perpendicular to the arrangement direction, with the angle ranging from 3.0° to 8.0°; the other is that each ring of nozzles is tilted in a clockwise or counterclockwise direction, with adjacent rings tilting in opposite directions, with the tilt angle ranging from 3.0° to 10.0°.

[0018] The staggered array distribution has adjacent rows of nozzles tilted in opposite directions at the same angle, with the tilt angle ranging from 3.0° to 10.0°.

[0019] This patent has the following advantages compared to existing nozzles and burners:

[0020] The shape of the oxidant nozzle opening provides a sufficiently large scattering area, allowing the process gas and oxidant to mix thoroughly at the nozzle outlet, improving the combustion efficiency of the process gas, forming a uniform temperature distribution in the reactor combustion chamber, effectively reducing the energy density of the core combustion zone, and ensuring a low temperature across the catalyst bed height section to prevent catalyst deactivation and sintering.

[0021] The circular tangent nozzle enhances the entrainment effect of the jet, improving combustion efficiency. The nozzle outlet design results in a short, concentrated flame shape, reducing the length of the high-temperature core flow and ensuring uniform heat radiation throughout the combustion chamber, thus mitigating overheating of the catalyst bed. The cleverly designed circular tangent outlet also alleviates stress concentration, allowing the nozzle to maintain its original dimensions without thermal deformation even under prolonged high-temperature operation.

[0022] Multiple sets of circular nozzles achieve reasonable air distribution and combustion conversion in the combustion chamber through different combinations and arrangements. For cylindrical or conical combustion chambers, the nozzles are distributed in a circular or radial array. For square combustion chambers, the nozzles are distributed in a U-shape or staggered arrangement. Each nozzle maintains a specific angle, and the groups of nozzles cooperate with each other to enhance local small eddies, reduce the cohesion effect between small flames, control the flow field of the combustion chamber reasonably and reliably, and ensure the uniform distribution of thermal energy in the combustion chamber. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a circularly tangential flat flame nozzle according to this application;

[0024] Figure 2 This is a schematic diagram of the circumferential array of the circular-cut nozzle of this application;

[0025] Figure 3 This is a schematic diagram of the radial array of the circular-cut nozzle of this application;

[0026] Figure 4 This is a schematic diagram of the circular cut nozzle of the present invention in a U-shape array;

[0027] Figure 5 This is a schematic diagram of the staggered distribution array of the circular tangent nozzle of the present invention;

[0028] Figure 6 The results of extensive CFD calculations on single nozzles with different outlet shapes are shown in the figure.

[0029] Figure 7 This is a structural comparison diagram of nozzles with and without circular cuts.

[0030] Figure 8 This is a flow field diagram showing the results of a multi-nozzle combination.

[0031] The reference numerals are as follows: 1. Nozzle body; 11. Inlet end; 12. Outlet end. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments disclosed in the present invention will be described in further detail below with reference to the accompanying drawings.

[0033] This application discloses a circularly tangential flat flame nozzle, such as... Figure 1 As shown, the nozzle includes a nozzle body 1. The inlet end 11 of the nozzle body has a circular cross-section, and the outlet end 12 of the nozzle body has a circular tangent. The outlet projection of the nozzle body is elliptical. The center of the ellipse is on the axis of the nozzle body inlet. The inlet of the nozzle body is used to connect to a pipe. Both the pipe and the nozzle body are located inside the burner. The other end of the pipe is connected to the oxidant inlet of the burner, and gaseous oxidant is introduced into the pipe.

[0034] The ratio of the projected area of ​​the inlet and outlet of the nozzle body is (1-1.2):1 to ensure pressure drop.

[0035] The ratio of the major and minor axes of the ellipse projected from the nozzle body's outlet is (3-5):1.

[0036] The nozzle body opening is deformed from a circle to an elliptical outlet along the axis. The inner and outer sides of the nozzle are modified by wire cutting, and then the nozzle outlet is cut with an arc with an arc degree of 100°-130°.

[0037] The end face of the nozzle body at the outlet end is rounded at the edges between the inner and outer walls of the nozzle body, with a radius of R = 0.5 mm to R = 2 mm.

[0038] This embodiment also discloses a combined array structure of circularly tangential flat flame nozzles, such as... Figures 2-5 As shown, it includes multiple nozzle bodies used in conjunction. For cylindrical or conical combustion chambers, the multiple nozzle bodies are distributed in a circumferential or radial array; for square combustion chambers, the multiple nozzle bodies are distributed in a U-shaped or staggered array.

[0039] like Figure 2 As shown, the circumferential array distribution includes a central nozzle and 2 to 4 rings of nozzles centered on the central nozzle. Each ring of nozzles, except for the central nozzle, contains at least 3 nozzle bodies.

[0040] The nozzles in the circular array are evenly distributed around the center nozzle at a certain angle to each other, with the spray angle spreading outwards. The angle between the axis of the second ring of nozzles and the axis of the center nozzle is 3.5° to 4.5°, the angle between the axis of the third ring of nozzles and the axis of the center nozzle is 5.5° to 8.0°, and the angle between the axis of the fourth ring of nozzles and the axis of the center nozzle is 8.5° to 9.5°.

[0041] like Figure 3 As shown, the radial array distribution includes 5 to 9 rows of nozzles, each row containing 3 to 5 nozzles arranged in a straight line, with multiple rows arranged in a circle around a central axis. The radial array distribution has no central nozzle; that is, there is no nozzle at the central axis position. Nozzles of the same position in different rows are on the same circumference, forming multiple rings of nozzles. Each ring of nozzles is at a certain angle to the central axis, with the spray angle spreading outwards. The angle of the first ring is 1.5°–2.5°, the second ring is 3.0°–4.0°, the third ring is 4.5°–6.0°, the fourth ring is 6.5°–7.5°, and the fifth ring is 8.0°–8.5°.

[0042] like Figure 4 As shown in Figures a and b, the zigzag array distribution includes 2 to 3 layers of nozzles. Each layer of nozzles is arranged in a rectangular shape. There are two arrangement methods for the nozzles in the zigzag array distribution: one is that two adjacent nozzles in the same layer spray gas in opposite directions at a certain angle perpendicular to the arrangement direction, with the angle ranging from 3.0° to 8.0°; the other is that each layer of nozzles is tilted in a clockwise or counterclockwise direction, with adjacent layers tilting in opposite directions, with the tilt angle ranging from 3.0° to 10.0°.

[0043] like Figure 5 As shown, the staggered array distribution includes 3 to 6 rows of nozzles. Each row of nozzles includes multiple nozzle bodies arranged in a straight line, with adjacent rows of nozzles parallel to each other. The adjacent rows of nozzles are tilted in opposite directions at the same angle, with the tilt angle ranging from 3.0° to 10.0°.

[0044] The oxidant flows through a pipe and is injected into the combustion chamber at a specific angle through the nozzle body. Ejected from multiple nozzles, it enhances the entrainment effect at the nozzle outlet, promoting uniform mixing of the oxidant and process gas. The oxidant ejected from the nozzle reacts violently with the process gas, forming multiple flames in the combustion chamber. Each flame is short and concentrated, and the distribution of different flames is uniform and reasonable, reducing the aggregation effect between flames. This results in a uniform temperature distribution in the combustion chamber and a low temperature in the core combustion zone. The rounded corners on both sides of the nozzle outlet and the tangential outlet design significantly improve the flow field and reduce the pressure drop on the oxidant side (from the oxidant inlet to the nozzle outlet). The tangential outlet greatly reduces collapse deformation caused by thermal stress, which is beneficial for long-term stable operation of the burner, reduces the possibility of catalyst failure, and avoids economic losses caused by frequent furnace shutdowns. Nozzle installation is convenient and quick, requiring only one weld at the end of the tube bundle in a tube bundle burner or on the ring tube in a ring tube burner.

[0045] like Figure 6As shown, through extensive CFD calculations on single nozzles with different outlet shapes, the elliptical outlet nozzle, compared with other types of nozzles, can significantly shorten the high-temperature core flow length, accelerate the energy decay in the central combustion zone, and reduce the high-temperature radiation to the fluid medium in the combustion chamber, which aligns with the design principles of short flat flame nozzles.

[0046] By changing the ratio of the major and minor axes of the elliptical outlet, extensive CFD calculations have shown that when the ratio is between 3 and 5, the length of the high-temperature zone is relatively short, and the temperature gradient is large for the same injection distance. Therefore, the preferred ratio of the major and minor axes is 3 to 5.

[0047] The elliptical outlet nozzle was further optimized by modifying the elliptical outlet with a circular arc of a specific curvature. The nozzle before and after modification are as follows: Figure 7 As shown. The modified nozzle can generate a larger scattering area, enhance the entrainment of external gas, and further improve the energy attenuation rate in the jet region. It also has a smaller projected area in the high-temperature radiation zone and a lower temperature distribution at the same height cross-section. For example... Figure 8 As shown.

[0048] The temperature in the reactor combustion zone reaches over 1,000 degrees Celsius. Under such harsh conditions, the requirements for the burner nozzles are stringent. The nozzle outlet (i.e. the fire-facing part) needs to withstand long-term high-temperature baking without deformation in order to ensure nozzle performance and long-term equipment operation.

[0049] To reduce nozzle stress deformation at high temperatures, sharp structures such as edges and corners need to be avoided. Numerical simulations were performed on the selected elliptical and circularly shaped outlet nozzles, comparing their deformation under the same high-temperature and high-pressure conditions. The conclusion is that the deformation of the circularly shaped nozzle is significantly less than that of the elliptical nozzle. The elliptical nozzle exhibits less tensile deformation along its major axis and less collapse deformation along its minor axis. Under high-temperature and high-pressure conditions, this design better ensures the nozzle dimensions, structurally preventing the generation of thermal stress and effectively extending the nozzle's lifespan.

[0050] The inner and outer edges of the nozzle outlet are rounded to minimize local stress concentration.

[0051] Among the indicators for evaluating burner performance, establishing a reasonable flow field in the combustion chamber is extremely important. This invention achieves the purpose of reasonable air distribution and organized combustion conversion by arranging nozzles in different arrays, establishing a good flow field, realizing uniform furnace temperature distribution, and improving process gas conversion efficiency.

[0052] The contents not described in detail in this application specification are common knowledge to those skilled in the art.

[0053] The present application has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present application. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and implementation methods of the present application without departing from the spirit and scope of the present application, and all such modifications and improvements fall within the scope of the present application. The scope of protection of the present application is determined by the appended claims.

Claims

1. A circularly tangential flat flame nozzle, characterized in that: The nozzle body (1) includes an inlet end (11) and an outlet end (12) at both ends. The gaseous oxidant enters from the inlet end (11) and is ejected from the outlet end (12). The inlet end (11) has a circular cross-section. The projection of the outlet end (12) along the axis of the inlet end of the nozzle body is elliptical. The outlet end (12) is arc-shaped. The axis of the arc is perpendicular to the plane containing the major axis of the ellipse and the axis of the inlet end, and the axis of the arc intersects with the axis of the inlet end. The nozzle body (1) is gradually deformed from a circle to an ellipse along the axial direction from the inlet end (11) to the outlet end (12); the inner and outer sides of the nozzle body are modified by wire cutting, and then the nozzle outlet is cut with an arc to form an arc shape. The ratio of the projected area of ​​the nozzle body's inlet to its outlet is (1-1.2):1 to ensure pressure drop. The ratio of the major and minor axes of the ellipse projected from the outlet end (12) is (3-5):

1.

2. A circularly tangential flat flame nozzle according to claim 1, characterized in that: The arc has an arc radius of 100° to 130°.

3. A circular tangential flat flame nozzle according to claim 1, characterized in that: The end face of the outlet end (12) is rounded at the edges between the inner and outer walls of the nozzle body, with a radius of R=0.5mm to R=2mm.

4. A combined array structure of circularly tangential flat flame nozzles, characterized in that, The nozzle body (1) is disposed in the combustion chamber and includes a plurality of nozzle bodies (1) as described in any one of claims 1-3. The inlet end (11) of the nozzle body (1) is connected to the oxidant inlet of the combustion chamber through a pipeline. For cylindrical or conical combustion chambers, the plurality of nozzle bodies are arranged in a circumferential array or a radial array; for square combustion chambers, the plurality of nozzle bodies are arranged in a U-shaped array or a staggered array.

5. The combined arrangement array structure of a circularly tangential flat flame nozzle according to claim 4, characterized in that: The circumferential array distribution includes a central nozzle and two to four rings of nozzles centered on the central nozzle. Each ring of nozzles, except for the central nozzle, contains at least three nozzle bodies. Each ring of nozzles extends outwards at a certain angle from the axis of the central nozzle. As they move further away from the central nozzle, the angle between the axis of the nozzle body and the axis of the central nozzle gradually increases. The angle between the axis of the outermost ring of nozzles and the axis of the central nozzle is 8.5° to 9.5°.

6. The combined arrangement array structure of a circularly tangential flat flame nozzle according to claim 4, characterized in that: The radial array distribution includes 5 to 9 rows of nozzles, each row containing 3 to 5 nozzle bodies arranged in a straight line. The axes of multiple rows are distributed in a circle around the central axis. The nozzle bodies of the same position in different rows are on the same circle, forming multiple rings of nozzles. Each ring of nozzles is at a certain angle to the central axis, and the spray angle spreads outward. Along the direction that gradually moves away from the central axis, the angle between the axis of the nozzle body of different rings and the central axis gradually increases, and the angle between the axis of the outermost ring of nozzle body and the central axis is 8.0° to 8.5°.

7. The combined arrangement array structure of a circularly tangential flat flame nozzle according to claim 4, characterized in that: The zigzag array distribution includes 2 to 3 layers of nozzles, each layer of nozzles includes multiple nozzle bodies, and the multiple nozzle bodies of each layer of nozzles are arranged in a rectangular shape. The nozzle body is arranged in either the first or the second manner; The first type: The nozzle bodies of multiple nozzles in each layer are tilted in a clockwise or counterclockwise direction, with adjacent layers tilting in opposite directions, and the tilt angle is 3.0° to 10.0°. The second method involves two adjacent nozzles on the same layer spraying gas in opposite directions at a certain angle perpendicular to the arrangement direction, with the angle ranging from 3.0° to 8.0°.

8. The combined arrangement array structure of a circularly tangential flat flame nozzle according to claim 4, characterized in that: The staggered array distribution includes 3 to 6 rows of nozzles. Each row of nozzles includes multiple nozzle bodies arranged in a straight line, with adjacent rows of nozzles parallel to each other. The nozzle bodies of adjacent rows of nozzles are tilted in opposite directions at the same angle, with the tilt angle ranging from 3.0° to 10.0°.

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