Circular cutting type flat flame nozzle and combined arrangement array structure thereof

Abstract

The invention discloses a circular cutting type flat flame nozzle and a combined arrangement array structure thereof, and relates to the field of nozzle structures, the circular cutting type flat flame nozzle comprises a nozzle body, the two ends of the nozzle body are an inlet end and an outlet end, a gaseous oxidizing agent enters from the inlet end and is sprayed out from the outlet end, and the section of the inlet end is circular; the projection of the outlet end in the axis direction of the inlet end of the nozzle body is oval, the outlet end is arc-shaped, the axis of the arc is perpendicular to the plane where the long axis of the oval and the axis of the inlet end are located, and the axis of the arc intersects with the axis of the inlet end. A large enough scattering area is provided, process gas and an oxidizing agent are fully mixed at a nozzle outlet, the combustion efficiency of the process gas is improved, and uniform temperature distribution is formed in a reactor combustion chamber.

Description

Technical Field

[0001] The invention relates to a circular cut 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 reformer in the synthetic ammonia device, and can also be used for preheating the furnace. Background Art

[0002] At present, the single nozzle outlet types of the burners used in the second-stage furnace of the synthetic ammonia plant are mostly trumpet-shaped, circular or elliptical. The above-mentioned nozzles have the problems of small scattering area and small temperature gradient in the jet zone, which can easily cause over-temperature deactivation of the catalyst bed; there are stress concentration areas in the nozzle body, which will cause high-temperature creep in a high-temperature environment for a long time, affecting the life of the equipment; the existing burners have unreasonable nozzle distribution, uneven flow field distribution causing dead zones, and flame licking the furnace to avoid burning furnace bricks, which are extremely unfavorable to the long-term stable operation of the device. Summary of the invention

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

[0004] How to ensure the long-term stable operation of the catalytic device, reduce the frequency of furnace turnover, and avoid sintering, shedding or high-temperature deactivation of the catalyst bed is the design starting point of this patent. The use of a circular cut flat flame nozzle introduced in this patent, installed on a tube bundle burner or annular tube burner, can enable the catalytic reactor to operate for a long period of time. Under long-term high temperature conditions, the burner itself will not be seriously deformed. The circular cut design of the nozzle minimizes the collapse deformation caused by thermal stress to ensure the normal operation of the entire device; the combined arrangement array of the nozzle can achieve reasonable air distribution and organize combustion conversion, the oxidant and process gas are well mixed, and they are fully mixed before combustion. The energy density is evenly distributed, the conversion temperature of the same height section in the furnace is uniform and the temperature of the core combustion area is relatively low, ensuring that the catalyst bed will not be over-temperature deactivated and avoiding catalyst sintering and melting.

[0005] The technical solutions provided by this application are as follows:

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

[0007] The ratio of the major axis to the minor axis of the ellipse of the outlet projection is 3 to 5.

[0008] The nozzle opening is deformed from a circle to an elliptical outlet along the axial direction, the inside and outside of the nozzle are trimmed by wire cutting, and then the nozzle outlet is cut with an arc, and the arc curvature is preferably 100° to 130°.

[0009] The edges between the end surface of the outlet end and the inner wall and the outer wall of the nozzle body are rounded, and the size of the rounded corners is R=0.5mm to R=2mm.

[0010] On the second aspect, a combined arrangement array structure of a circular-cut flat-flame nozzle is provided, which is usually composed of multiple groups of nozzles for use in combination. For a cylindrical or conical combustion chamber, multiple nozzle bodies are distributed in a circular array or a radial array; for a square combustion chamber, multiple nozzle bodies are distributed in a U-shaped array or a staggered array.

[0011] The circular array distribution generally includes 2 to 4 groups of nozzles (including the central nozzle), and each group includes at least 3 nozzles except the central nozzle.

[0012] The radial array distribution generally arranges 5 to 9 columns of nozzles, and each column includes 3 to 5 nozzles.

[0013] The U-shaped array distribution generally has 2 to 3 layers of nozzles.

[0014] The staggered array distribution generally arranges 3 to 6 rows of nozzles.

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

[0016] The radial array is distributed without a central nozzle. Each circle 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 first circle is 1.5° to 2.5°, the angle of the second circle is 3.0° to 4.0°, the angle of the third circle is 4.5° to 6.0°, the angle of the fourth circle is 6.5° to 7.5°, and the angle of the fifth circle is 8.0° to 8.5°.

[0017] The nozzles are arranged in the U-shaped array in two ways. One is that adjacent nozzles spray gas in opposite directions at a certain angle perpendicular to the arrangement direction, and the angle is 3.0° to 8.0°; the other is that each circle of nozzles is inclined in a clockwise or counterclockwise direction, and adjacent circles are inclined in opposite directions, and the inclination angle is 3.0° to 10.0°.

[0018] In the staggered array distribution, two adjacent rows of nozzles are inclined in opposite directions with the same angle, and the inclination angle is 3.0° to 10.0°.

[0019] Compared with existing nozzles and burners, this patent has the following advantages:

[0020] The opening shape of the oxidant nozzle provides a sufficiently large scattering area, and the process gas and oxidant are fully mixed at the nozzle outlet, which improves the combustion efficiency of the process gas and forms a uniform temperature distribution in the reactor combustion chamber, effectively reducing the energy density of the core combustion zone, ensuring that the catalyst bed has a lower temperature at the height section, and preventing the catalyst from being deactivated and sintered.

[0021] The circular cut nozzle can strengthen the entrainment effect of the jet and improve the combustion efficiency. The circular cut nozzle outlet controls the flame shape to be short and concentrated, reduces the length of the high-temperature core flow, makes the overall heat radiation of the combustion chamber uniform, and reduces the over-temperature radiation to the catalyst bed. The circular cut nozzle outlet design cleverly alleviates the problem of stress concentration, and can maintain the original size without thermal deformation when operating in a high-temperature environment for a long time.

[0022] Multiple groups of circular cut nozzles are arranged in different combinations to achieve reasonable air distribution and organize combustion conversion in the combustion chamber. 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-shaped or staggered row. Each nozzle maintains a specific angle, and each group of nozzles cooperates with each other to enhance local small vortices, reduce the aggregation effect between small flames, control the flow field in the combustion chamber reasonably and reliably, and ensure uniform distribution of thermal energy in the combustion chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of a circular cut flat flame nozzle of the present application;

[0024] Figure 2 A schematic diagram of a circular array of circular cut nozzles of the present application;

[0025] Figure 3 A schematic diagram of a radial array of circular cut nozzles of the present application;

[0026] Figure 4 It is a schematic diagram of a U-shaped array of circular cut nozzles of the present invention;

[0027] Figure 5 It is a schematic diagram of the staggered distribution array of the circular cut nozzles of the present invention;

[0028] Figure 6 Results of a large number of CFD calculations on a single nozzle with different exit shapes;

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

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

[0031] Description of the accompanying drawings: 1, nozzle body; 11, inlet end; 12, outlet end. DETAILED DESCRIPTION

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

[0033] The present application embodiment discloses a circular cut flat flame nozzle, such as Figure 1 As shown, it includes a nozzle body 1, the inlet end 11 of the nozzle body is circular in cross section, the outlet end 12 of the nozzle body is circular cut, and the outlet projection of the nozzle body is elliptical. The center of the ellipse is on the axis of the inlet of the nozzle body. The inlet of the nozzle body is used to connect the pipeline, the pipeline and the nozzle body are both located in the burner, and the other end of the pipeline is connected to the oxidant inlet of the burner, and the pipeline is used to pass the gaseous oxidant.

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

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

[0036] The opening of the nozzle body is deformed from a circle to an elliptical outlet along the axial direction. The inside and outside of the nozzle are trimmed by wire cutting, and then the nozzle outlet is cut with an arc, and the arc angle is 100°-130°.

[0037] The edges between the end surface of the outlet end of the nozzle body and the inner wall and the outer wall of the nozzle body are rounded, and the size of the rounded corners is R=0.5mm to R=2mm.

[0038] This embodiment also discloses a combined arrangement array structure of a circular cut flat flame nozzle, such as Figure 2-Figure 5 As shown, it includes multiple nozzle bodies used in combination. For a cylindrical or conical combustion chamber, the multiple nozzle bodies are distributed in a circular or radial array; for a square combustion chamber, the multiple nozzle bodies are distributed in a U-shaped or staggered array.

[0039] like Figure 2 As shown, the circular array distribution includes a central nozzle and 2 to 4 circles of nozzles with the central nozzle as the center. Except for the central nozzle, each circle of nozzles contains at least 3 nozzle bodies.

[0040] Each circle of nozzles in the circular array is evenly distributed at a certain angle to the axis direction of the central nozzle, and the injection angle spreads outward. The angle between the axis of the second circle of nozzle bodies and the axis of the central nozzle is 3.5°~4.5°, the angle between the axis of the third circle of nozzle bodies and the axis of the central nozzle is 5.5°~8.0°, and the angle between the axis of the fourth circle of nozzle bodies and the axis of the central nozzle is 8.5°~9.5°.

[0041] like Figure 3 As shown, the radial array distribution includes 5 to 9 rows of nozzles, each row contains 3 to 5 nozzles arranged in a straight line, and the axes of multiple rows are distributed in a circle around the central axis. There is no central nozzle in the radial array distribution, that is, there is no nozzle at the central axis position. Nozzles of the same arrangement position in different rows are on the same circumference, forming multiple circles of nozzles. Each circle of nozzles is at a certain angle to the central axis, and the spray angle spreads outward. The angle of the first circle is 1.5°~2.5°, the angle of the second circle is 3.0°~4.0°, the angle of the third circle is 4.5°~6.0°, the angle of the fourth circle is 6.5°~7.5°, and the angle of the fifth circle is 8.0°~8.5°.

[0042] like Figure 4 As shown in Figures a and b, the U-shaped array distribution includes 2 to 3 layers of nozzles. Each layer of nozzles is arranged in a rectangular shape. There are two ways to arrange the nozzles in the U-shaped array. One is that two adjacent nozzles in the same layer spray gas in opposite directions at a certain angle perpendicular to the arrangement direction, and the angle is 3.0° to 8.0°; the other is that each layer of nozzles is tilted in a clockwise or counterclockwise direction, and the adjacent layers are tilted in opposite directions, and the tilt angle is 3.0° to 10.0°.

[0043] like Figure 5 As shown, the staggered array includes 3 to 6 rows of nozzles, each row of nozzles includes a plurality of nozzle bodies arranged in a straight line, and two adjacent rows of nozzles are parallel. The two adjacent rows of nozzles are inclined in opposite directions and have the same angle, and the inclination angle is 3.0° to 10.0°.

[0044] The oxidant flows through the nozzle body through the pipeline and is sprayed into the combustion chamber at a specific angle. Spraying from multiple groups of nozzles enhances the entrainment effect of the nozzle outlet and promotes the uniform mixing of the oxidant and the process gas; the oxidant sprayed from the nozzle reacts violently with the process gas, forming multiple flames in the combustion chamber, the single flame is short and concentrated, and the flames of different strands are evenly and reasonably distributed, which reduces the polymerization effect between flames, the temperature distribution of the combustion chamber is even, and the temperature of the core combustion area is low; the inside and outside of the nozzle outlet are chamfered, and the circular cut outlet design significantly improves the flow field and reduces the pressure drop on the oxidant side (the oxidant side is: the oxidant inlet of the burner to the nozzle outlet); the circular cut outlet greatly reduces the collapse deformation caused by thermal stress, which is conducive to the long-term stable operation of the burner; reduces the possibility of catalyst failure; avoids economic losses caused by frequent furnace reversal; the nozzle is easy and quick to install, and only needs to add a weld at the end of the tube bundle of the tube bundle burner or on the ring tube of the ring tube burner.

[0045] like Figure 6As shown in the figure, through a large number of CFD calculations on single nozzles with different outlet shapes, it is found that the nozzle with elliptical outlet can significantly shorten the length of high-temperature core flow compared with nozzles of other structural types, the energy attenuation in the central combustion area is fast, and the high-temperature radiation to the fluid medium in the combustion chamber is reduced, which is in line with the design starting point of the short flat flame nozzle.

[0046] By changing the ratio of the major and minor axes of the elliptical outlet, it is found through a large number of CFD calculations that when the ratio of the major and minor axes 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 ratio of the major and minor axes is preferably 3 to 5.

[0047] The elliptical outlet nozzle is further optimized and the elliptical outlet is modified with a circular arc of a specific curvature. The nozzle before and after the modification is as follows Figure 7 As shown in the figure. The modified nozzle can produce a larger scattering area, enhance the entrainment effect on the external gas, and further improve the energy attenuation rate of the jet zone. The projected area of ​​the high-temperature radiation zone is small, and there is a lower temperature distribution on the same height section. Figure 8 shown.

[0048] The temperature in the combustion zone of the reactor is as high as over one thousand degrees Celsius. Under such harsh working conditions, strict requirements are placed on the burner nozzle. The nozzle outlet (i.e. the fire-facing part) needs to withstand long-term high-temperature baking and cannot deform to ensure the nozzle performance and long-term operation of the equipment.

[0049] In order to reduce the stress deformation of the nozzle under high temperature, it is necessary to avoid sharp structures such as edges and corners. The optimal elliptical and circular cut outlet nozzles are numerically simulated, and the deformation of the two under the same high temperature and high pressure conditions is compared. It is concluded that the deformation of the circular cut nozzle is significantly smaller than that of the elliptical nozzle. The elliptical nozzle has a small tensile deformation in the long axis direction and a small collapse deformation in the short axis direction. When operating under high temperature and high pressure conditions, the nozzle size can be better guaranteed, and the generation of thermal stress can be avoided from the structure, thereby effectively extending the life of the nozzle.

[0050] The inside and outside of the nozzle outlet are rounded to avoid local stress concentration to the greatest extent possible.

[0051] Among the indicators for evaluating burner performance, establishing a reasonable flow field in the combustion chamber is extremely important. The present invention achieves the purpose of reasonable air distribution and organized combustion conversion through different array arrangements of nozzles, establishes a good flow field, realizes uniform furnace temperature distribution, and improves process gas conversion efficiency.

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

[0053] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.

Claims

1. A circular cut flat flame nozzle, characterized in that: The nozzle body (1) comprises an inlet end (11) and an outlet end (12) at two ends of the nozzle body (1). A 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, and the projection of the outlet end (12) along the axis of the inlet end of the nozzle body is an ellipse. The outlet end (12) is an arc, and the axis of the arc is perpendicular to the major axis of the ellipse and the plane where the axis of the inlet end is located, and the axis of the arc intersects with the axis of the inlet end.

2. A circular cut flat flame nozzle according to claim 1, characterized in that: The ratio of the major axis to the minor axis of the ellipse projected at the outlet end (12) is (3-5):

1.

3. The circular cut flat flame nozzle according to claim 1, characterized in that: The nozzle body (1) is gradually deformed from a circular shape to an elliptical shape from the inlet end (11) to the outlet end (12) along the axial direction; the inner and outer sides of the nozzle body are trimmed by wire cutting, and the nozzle outlet is cut with an arc to form an arc shape.

4. The circular cut flat flame nozzle according to claim 1, characterized in that: The arc has an angle of 100° to 130°.

5. The circular cut flat flame nozzle according to claim 1, characterized in that: The edges between the end surface of the outlet end (12) and the inner wall and outer wall of the nozzle body are rounded, and the size of the rounded corners is R=0.5mm to R=2mm.

6. A combined arrangement array structure of circular cut flat flame nozzles, characterized in that: The invention is arranged in a combustion chamber, comprising a plurality of nozzle bodies (1) as described in any one of claims 1 to 5, wherein the inlet end (11) of the nozzle body (1) is connected to the oxidant inlet of the combustion chamber through a pipeline. For a cylindrical or conical combustion chamber, the plurality of nozzle bodies are distributed in a circular array or a radial array; for a square combustion chamber, the plurality of nozzle bodies are distributed in a U-shaped array or a staggered array.

7. The combined arrangement array structure of the circular cut flat flame nozzles according to claim 6, characterized in that: The circular array distribution includes a central nozzle and 2 to 4 circles of nozzles with the central nozzle as the center, and each circle of nozzles except the central nozzle includes at least 3 nozzle bodies; Each circle of nozzle bodies spreads outward at a certain angle to the axis of the central nozzle. As they move away from the central nozzle, the angles between the axes of nozzle bodies in different circles and the axis of the central nozzle gradually increase. The angle between the axis of the nozzle bodies in the outermost circle and the axis of the central nozzle is 8.5° to 9.5°.

8. The combined arrangement array structure of the circular cut flat flame nozzles according to claim 6, characterized in that: The radial array distribution includes 5 to 9 rows of nozzles, each row contains 3 to 5 nozzle bodies arranged in a straight line, the axes of multiple rows are distributed in a circle around the central axis, and the nozzle bodies of the same arrangement position in different rows are on the same circumference to form multiple circles of nozzles. Each circle of nozzles is at a certain angle to the central axis, and the injection angle spreads outward; along the direction gradually away from the central axis, the angle between the axes of the nozzle bodies in different circles and the central axis gradually increases, and the angle between the axes of the nozzle bodies in the outermost circle and the central axis is 8.0°~8.5°.

9. The combined arrangement array structure of the circular cut flat flame nozzles according to claim 6, characterized in that: The U-shaped array distribution includes 2 to 3 layers of nozzles, each layer of nozzles includes a plurality of nozzle bodies, and the plurality of nozzle bodies of each layer of nozzles are arranged in a rectangular shape; The arrangement of the nozzle body is the first or second type; The first type: multiple nozzle bodies of each layer of nozzles are tilted in a clockwise or counterclockwise direction, and the tilt directions of adjacent layers are opposite, with a tilt angle of 3.0° to 10.0°; The second type: two adjacent nozzles in the same layer spray gas in opposite directions at a certain angle perpendicular to the arrangement direction, and the angle is 3.0° to 8.0°.

10. The combined arrangement array structure of the circular cut flat flame nozzles according to claim 6, characterized in that: The staggered array distribution includes 3 to 6 rows of nozzles, each row of nozzles includes a plurality of nozzle bodies arranged in a straight line, and two adjacent rows of nozzles are parallel; the nozzle bodies of two adjacent rows of nozzles are inclined in opposite directions and have the same angle, and the inclination angle is 3.0° to 10.0°.

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