A high-efficiency circulating uniform fluidizer and spouted bed

Abstract

The present invention provides a uniform fluidizer and a spouted bed with high efficiency circulation. The uniform fluidizer is arranged in the main body of the spouted bed. The fluidizer includes a jet bucket body which is arranged to taper from top to bottom and is open at the top. The bottom of the jet bucket body is provided with a main nozzle. A plurality of side nozzles are distributed on the side wall of the jet bucket body. The bottom of the jet bucket body is also fixed with the bottom end of a swirl blade. The axial center axis of the swirl blade coincides with the axial center axis of the jet bucket body. The jet bucket body is installed at the bottom of the main body of the spouted bed. The top edge of the jet bucket body is contacted and sealed with the inner wall of the main body of the spouted bed. The space between the jet bucket body and the main body of the spouted bed is a conical annular air inlet channel. The top of the swirl blade is flush with the air outlet at the top of the straight tube section. The axial center axis of the swirl blade coincides with the axial center axis of the straight tube section. The uniform fluidizer of the present invention allows gas to contact particles quickly, improves circulation efficiency, and improves the overall material processing capacity of the spouted bed.

Description

Technical Field

[0001] The invention belongs to the field of chemical equipment and relates to a spouted bed, in particular to a high-efficiency circulating uniform fluidizer and a spouted bed. Background Art

[0002] The column-cone spouted bed is a highly efficient gas-solid reactor that is currently developing very rapidly. It has been widely used in various unit operations in the field of chemical production, such as drying, coating, granulation of large particles, low-temperature pyrolysis of waste rubber, and drying and crushing of solutions, gasification of low-quality coal, desulfurization of coal-fired flue gas, desulfurization and removal of hydrochloric acid gas from waste incineration flue gas, and removal of carbon dioxide, etc.

[0003] The development of spouted beds has been going on for more than 50 years. There are many forms of spouted beds, among which the most widely used and typical spouted bed is the cylindrical cone spouted bed, which has an obvious three-zone flow structure: dilute phase injection zone, dense phase annular gap zone and fountain zone. The particles in the injection zone are entrained by high-speed gas and come into contact with the gas in the downstream. When the particles fall back from the fountain zone to the annular gap zone, they slowly move downward and come into countercurrent contact with the gas in the annular gap zone. That is, the medium particles of the spouted bed have obvious internal and external stratified flow characteristics. However, for the treatment of fine particles, this spouted bed also has some shortcomings: the particles in the annular gap zone, especially the spouted bed cone zone, move slowly, the particles agglomerate, nodules and even flow dead zones appear, and the particles and gas in the annular gap zone and the injection zone lack radial mixing, which affects and reduces the overall material treatment efficiency and chemical reaction rate of the spouted bed. Summary of the invention

[0004] In view of the deficiencies in the prior art, the object of the present invention is to provide a uniform fluidizer and spouted bed with high efficiency circulation, so as to solve the technical problem of insufficient circulation efficiency in the prior art while ensuring that no flow dead zones occur.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0006] A high-efficiency circulating spouted bed, comprising a spouted bed main body, wherein the spouted bed main body is divided into a straight pipe section and a conical pipe section which are connected in an axial direction, the top of the straight pipe section is an air outlet, the bottom of the conical pipe section is provided with an air inlet, and a uniform fluidizer is provided in the spouted bed main body;

[0007] The fluidizer comprises an air jet bucket body which is tapered from top to bottom in the axial direction and open at the top, a main nozzle is provided at the bottom of the air jet bucket body, a plurality of side nozzles are distributed on the side wall of the air jet bucket body, the bottom end of a swirl blade is also fixed to the bottom of the air jet bucket body, and the axial center axis of the swirl blade coincides with the axial center axis of the air jet bucket body;

[0008] The jet bucket is installed at the bottom of the spouted bed body, the top edge of the jet bucket is in contact and sealed with the inner wall of the spouted bed body, and the space between the jet bucket and the spouted bed body is a conical annular air inlet channel;

[0009] The top of the swirl blade is flush with the air outlet at the top of the straight tube section, and the axial center axis of the swirl blade coincides with the axial center axis of the straight tube section.

[0010] The present invention also protects a high-efficiency circulating uniform fluidizer, comprising an air jet bucket body which is axially arranged to taper with equal degrees from top to bottom and is open at the top, a main nozzle is provided at the bottom of the air jet bucket body, a plurality of side nozzles are distributed on the side wall of the air jet bucket body, the bottom end of a swirl blade is also fixed to the bottom of the air jet bucket body, and the axial center axis of the swirl blade coincides with the axial center axis of the air jet bucket body.

[0011] The present invention also has the following technical features:

[0012] The multiple side nozzles are distributed on the side wall of the jet bucket body in a sparse upper and dense lower pattern, divided into three layers: upper, middle and lower. The number of openings in the same layer in the middle is twice that of the same layer in the upper part, and the number of openings in the same layer in the lower part is twice that of the same layer in the middle.

[0013] The angle between the side wall of the air jet bucket and the horizontal plane is 40° to 60°.

[0014] The swirl blade is a single-head spiral swirl blade, and the number of rotations of the swirl blade is 3 to 7.

[0015] The width of the swirl blade is equal to the inner diameter of the main nozzle.

[0016] Compared with the prior art, the present invention has the following technical effects:

[0017] (I) Compared with the conventional spouted bed, the spouted bed of the present invention has a uniform fluidizer connected to the column cone connection of the spouted bed, which enhances the radial movement of particles in the spouting zone and the annular zone, and strengthens the momentum, heat and mass transfer process between the particles and the injected gas. The uniform fluidizer of the present invention allows the gas to contact the particles quickly, improves the circulation efficiency, and improves the overall material handling capacity of the spouted bed.

[0018] (II) Compared with the conventional spouted bed, the spouted bed of the present invention introduces the swirl effect so that the gas-solid two phases obtain a larger contact area, reduces the generation of flow dead zones in the conventional spouted bed, and reduces the residence time of the material in the bed layer, which has guiding significance for the treatment of heat-sensitive materials in industrial and agricultural production.

[0019] (III) The uniform fluidizer of the present invention has a simple structure, is easy to install and is convenient to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of the high-efficiency circulating spouted bed of the present invention.

[0021] Figure 2 It is a schematic structural diagram of the uniform fluidizer of the present invention.

[0022] FIG3 is a particle volume fraction distribution cloud diagram of Example 1 and the comparative example at t=5s, t=5.2s, t=5.4s, and t=5.6s after stable spouting in the bed on the axial section of the spouted bed at Y=0; FIG3(a) is a conventional spouted bed, and FIG3(b) is a spouted bed with high efficiency circulation.

[0023] Figure 4 shows the simulated temperature distribution cloud diagrams of the particles in the traditional spouted bed, multi-nozzle spouted bed and spouted bed equipped with a uniform fluidizer at relatively later time points t=10s, t=10.2s, t=10.4s and t=10.6s on the axial section Y=0 to ensure that the temperature in the bed reaches the equilibrium state; Figure 4(a) is a traditional spouted bed, Figure 4(b) is a multi-nozzle spouted bed, and Figure 4(c) is a high-efficiency circulating spouted bed.

[0024] Figure 5 shows the internal swirl blades rotating at different times (rotation) on the axial section Y = 0, i.e., r 1 =3Q, r 2 =5Q, r 3 =7Q case for comparison;

[0025] Figure 5(a) shows r 1 =3Q, Figure 5(b) is r 2 =5Q, Figure 5(c) is r 3 =7Q.

[0026] Figure 6 shows the different angles between the jet bucket and the horizontal plane, i.e., δ, at the selected time points of t=5s, 5.2s, 5.4s, and 5.6s on the axial section Y=0. 1 =60°, δ 2 =50°, δ 3 =40° for the case of comparison of particle volume fraction distribution cloud diagram; Figure 6 (a) is δ 1 =60°, Figure 6(b) is δ 2 =50°, Figure 6 (c) is δ 3 =40°.

[0027] Figure 7 The angles between the jet body and the horizontal plane, i.e., δ, are selected at the time points of t = 5s, 5.2s, 5.4s, and 5.6s on the axial section Y = 0. 1=60°, δ 2 =50°, δ 3 = Pressure distribution contour diagram for comparison of the case with 40°;

[0028] Figure 8 is the angle between the jet bucket and the horizontal plane, i.e., δ 1 =60°, δ 2 =50°, δ 3 =40° overall bed pressure drop distribution diagram of the spouted bed.

[0029] FIG. 9 is a solid pressure distribution cloud diagram, FIG. 9( a ) is a solid pressure distribution cloud diagram of a conventional spouted bed, and FIG. 9( b ) is a solid pressure distribution cloud diagram of a uniform fluidizer spouted bed.

[0030] The meanings of the numbers in the figure are: 1-spout bed body, 2-uniform fluidizer, 3-conical annular air inlet channel; 101-straight pipe section, 102-conical pipe section, 103-air inlet, 104-air outlet; 201-jet bucket, 202-main nozzle, 203-side nozzle, 204-swirl blade.

[0031] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0032] Introducing swirl effect in conventional fluid is a new type of secondary flow enhanced heat transfer technology. At the same time, combined with side nozzles, it can increase the resistance in exchange for a more effective enhanced heat transfer effect. It has become a cutting-edge research hotspot for enhanced heat exchange. The basic mechanism is as follows: when the reactor is working normally, part of the fluid is redistributed through the side nozzle and the main nozzle, part of it is ejected from the side wall to make the airflow have radial velocity, and part of it is strongly disturbed in the radial direction under the swirl of the swirler connected to the main nozzle, and the fluid rotates around the blades, so that the fluid contacts the particles in a spiral form, enhancing radial mixing. The strong fluid disturbance strengthens the momentum transfer and heat transfer between the fluid and the particles. Based on the principle of fluid swirl effect to enhance flow motion, the present invention will realize the radial motion of fine particles through gas swirl, destroy the accumulation of fine particles in the annular gap area and the cone area of ​​the spouted bed, thereby enhancing the mixing process of particles and fluids in the spouted bed.

[0033] It should be noted that the horizontal plane in the present invention refers to the axial section perpendicular to the axial center axis of the air injection bucket 201 .

[0034] It should be noted that, unless otherwise specified, all components and materials in the present invention are components and materials known in the art.

[0035] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0036] Embodiment 1:

[0037] This embodiment provides a highly efficient circulating spouted bed, such as Figure 1 and Figure 2 As shown, it comprises a spouted bed body 1, which is divided into a straight pipe section 101 and a conical pipe section 102 which are connected in an axial direction, the top of the straight pipe section 101 is a gas outlet 104, the bottom of the conical pipe section 102 is provided with a gas inlet 103, and a uniform fluidizer 2 is provided in the spouted bed body 1;

[0038] The fluidizer 2 includes an air jet bucket 201 which is tapered from top to bottom in the axial direction and is open at the top. A main nozzle 202 is provided at the bottom of the air jet bucket 201. A plurality of side nozzles 203 are distributed on the side wall of the air jet bucket 201. The bottom of the air jet bucket 201 is also fixed with the bottom end of a swirl blade 204. The axial center axis of the swirl blade 204 coincides with the axial center axis of the air jet bucket 201.

[0039] The jet bucket 201 is installed at the bottom of the spouted bed body 1, the top edge of the jet bucket 201 is in contact and sealed with the inner wall of the spouted bed body 1, and the space between the jet bucket 201 and the spouted bed body 1 is a conical annular air inlet channel 3;

[0040] The top of the swirl blade 204 is flush with the air outlet 104 at the top of the straight tube section 101 , and the axial center axis of the swirl blade 204 coincides with the axial center axis of the straight tube section 101 .

[0041] In the present invention, the spouted bed body 1 is an inverted cylindrical cone type spouted bed.

[0042] As a preferred solution of this embodiment, the distribution of multiple side nozzles 203 on the side wall of the jet bucket 201 is sparse at the top and dense at the bottom, and is divided into three layers: upper, middle and lower. The number of openings in the same layer in the middle is twice the number of openings in the same layer in the upper part, and the number of openings in the same layer in the lower part is twice the number of openings in the same layer in the middle.

[0043] As a preferred solution of this embodiment, the angle between the side wall of the air jet bucket 201 and the horizontal plane is 40° to 60°.

[0044] In the present invention, the swirl blades 204 mainly act on the air flow channel in the main body of the spouted bed, introducing a swirl effect in the gas phase that mainly moves in the vertical direction, causing a disturbance in the radial direction.

[0045] Specifically, the bottom end of the swirl blade 204 is connected to the main nozzle 202 at the bottom of the jet bucket 201 without gap. This can ensure that the swirl blade 204 has sufficient layout size and influence space, and can also ensure that the swirl blade 204 structure has the maximum influence on the internal flow field of the spouted bed body 1.

[0046] As a preferred solution of this embodiment, the swirl blade 204 is a single-head spiral swirl blade, and the number of rotations of the swirl blade 204 is 3 to 7 circles.

[0047] As a preferred solution of this embodiment, the width of the swirl blade 204 is equal to the inner diameter of the main nozzle 202 .

[0048] When the high-efficiency circulating spouted bed is working, the gas entering through the air inlet 103 is divided into two parts. One part continues to directly enter the straight pipe section 101 through the main nozzle 202 in the axial direction, and introduces a swirl effect under the action of the swirl blades 204 to produce radial disturbances; the other part passes through the conical annular air inlet channel 3, enters the jet bucket 201 from the side nozzle 203 of the jet bucket 201, and then enters the straight pipe section 101 axially.

[0049] Performance Testing:

[0050] As an example of a specific high-efficiency circulating spouted bed, the specific structural dimensions are as follows:

[0051] Air inlet diameter D 1 =24mm, cone section height H 1 =115mm, height of spouted bed body H=700mm, straight pipe section diameter D 2 =152mm. The angle between the conical tube section and the horizontal plane is 60°.

[0052] Main nozzle aperture D c =19mm, side nozzle aperture D s =4mm.

[0053] The distribution of multiple side nozzles on the side wall of the jet bucket is sparse at the top and dense at the bottom. The number of openings in the same layer at the top is n. 1 =4, the number of openings in the same layer in the middle n 2 =8, number of openings in the same layer at the bottom n 3 =12.

[0054] The width of the swirl blade is 19 mm and the thickness is 1 mm.

[0055] Taking the above-mentioned specific high-efficiency cycle spouted bed as an example, a performance test was carried out on it.

[0056] The calculation parameters and boundary conditions of the numerical simulation are shown in Tables 1 and 2.

[0057] Table 1 Geometric dimensions of spouted bed and numerical simulation parameter settings

[0058] Model parameters Parameter Value Model parameters Parameter Value Cylinder diameter 152mm Inlet diameter 24mm Full bed height 700mm Static bed height 325mm Cone Angle 30° Particle diameter 1.41mm Particle density <![CDATA[2503kg / m 3 ]]> Internal friction angle of particles 28.5° Maximum particle volume fraction 0.59 Maximum friction volume fraction of particles 0.588 Particle recovery coefficient 0.9 Operating pressure 0.1mpa Gas density <![CDATA[1.225kg / m 3 ]]> Gas viscosity <![CDATA[1.7894×10 -5 Step]]> Time step <![CDATA[2×10 -5 s]]> Calculation Convergence Criteria <![CDATA[1×10 -4 ]]>

[0059] Table 2 Model boundary condition settings

[0060]

[0061]

[0062] During operation, high-speed gas with a certain pressure enters the spouted bed from the air inlet, and is divided into axial and lateral parts at the bottom cone. Among them, most of the gas phase goes vertically upward directly into the main air inlet of the uniform cyclone. This part of the gas will produce a swirl effect on the internal swirl impeller, causing disturbances in the radial direction, and sending the air in the injection area into the fountain area and the annular gap area in a spiral shape, so that efficient contact is generated between the gas and solid phases, and more effective mixing of the two phases is achieved. It continues to rise and enters the fountain area. Then, under the influence of gravity, the material enters the annular gap area along the wall of the spouted bed and slowly descends in the annular gap area. Finally, due to the action of gravity, The particulate material returns to the bottom of the spouted bed; at this time, another part of the gas enters the gap between the bottom cone surfaces at the inlet, and then blows obliquely upward into the annular gap area of ​​the spouted bed through the openings in the side wall, introducing more gas phase in the area with higher solid phase stacking density, while increasing the scene disturbance between the gas and solid phases, greatly enhancing the gas-solid contact efficiency in the annular gap area, strengthening the boring reciprocating cycle, and achieving more efficient physical action or chemical reaction.

[0063] Control group 1:

[0064] In this comparative example, except that the uniform fluidizer 2 of the present invention is not installed, the bed of the spouted bed, other parameters and experimental conditions are the same as those of Example 1.

[0065] Control group 2:

[0066] In this comparative example, the bed of the spouted bed, other parameters and experimental conditions are the same as those in Example 1, except that the swirl blades 204 in the uniform fluidizer 2 of the present invention are not installed.

[0067] Through numerical simulation research, it can be seen that the effect of the uniform fluidizer on the flow in the spouted bed is as follows:

[0068] First, on the axial section at Y=0, the gas volume fraction distribution cloud diagrams of Example 1 and the comparative example at t=5s, t=5.2s, t=5.4s, and t=5.6s after stable spouting in the bed were selected respectively.

[0069] As shown in Figure 3, when the uniform cyclone is installed, the central swirl blade breaks the obvious three zones existing in the traditional spouted bed. Its flow pattern is more irregular than that of the traditional cylindrical cone spouted bed and the side nozzle spouted bed. The channel generated by the inlet gas breaking through the tightly packed solid particles is biased on the z-axis instead of being distributed in the center of the bed like the former two. But at the same time, we can also observe that after the gas-solid two-phase spouting in the bed reaches stability, the solid phase can still be observed to circulate in the bed within a certain time span. Compared with the traditional spouted bed and the spouted bed with only side nozzles, the new spouted bed that focuses on actively interfering with the gas flow direction with the internal swirl blades can guide the gas flow into the annular gap area, increase the radial mixing of the two phases, and stir some dead zones, thereby more efficiently improving the gas-solid contact efficiency of the spouted bed and improving the inherent defects of the traditional spouted bed.

[0070] Second, on the axial section Y=0, in order to ensure that the temperature in the bed reaches the equilibrium state, the simulated temperature distribution cloud diagrams of the traditional spouted bed, multi-nozzle spouted bed and spouted bed equipped with a uniform fluidizer are selected at relatively later time points of t=10s, 10.2, 10.4s and 10.6s, as shown in Figure 4.

[0071] As shown in the cloud diagram of Figure 4, after the internal swirl blades break the flow direction of the injection zone of the spouted bed, the center of the high-energy particles further moves in the bed over time. Most of the effective reactions of the spouted bed are concentrated in the annular gap area around the larger particle packing density. Therefore, compared with the traditional spouted bed that is concentrated at the bottom of the fountain area and within the injection area, the modified spouted bed can better ensure the full contact between particles and gas in various parts, thereby improving the overall bed's material processing efficiency.

[0072] Third, similarly, on the axial section Y=0, the time points selected are t=5s, 5.2s, 5.4s, and 5.6s respectively, and the rotation of the internal swirl blades is different, i.e., r 1 =3Q, r 2 =5Q, r 3 =7Q case for comparison, as shown in Figure 5.

[0073] From the particle volume fraction distribution diagram in Figure 5, it can be seen that with the increase of the rotation of the swirl blades in the spouted bed, the originally axial injection gas tends to move more along the axial direction. As shown in the figure, when r 1 =3Q, compared to r 2 =5Q, r 3=7Q The main contact surface between the gas and solid phases is near the axis. As the number of blade rotations increases, the airflow moves toward the wall under the corresponding action of the swirl, resulting in a significant decrease in the pressure drop on one side of the spouted bed compared to the other side. The volume fraction of solid particles on one side of the bed is significantly reduced, while the other side is densely packed, resulting in a decrease in the overall bed treatment efficiency. Therefore, r is selected 1 =3Q can ensure the radial disturbance of the gas phase to the particle phase, and can also concentrate the wall gas on one side of the spouted bed, resulting in a decrease in the gas-solid contact efficiency.

[0074] Fourth, similarly, on the axial section Y=0, different angles of the jet body, i.e., δ 1 =60°, δ 2 =50°, δ 3 =40°, as shown in Figure 6 (particle volume fraction distribution cloud diagram), Figure 7 (Pressure distribution cloud map), Figure 8 (Pressure drop distribution diagram) shown.

[0075] From Figure 6, Figure 7 From the cloud chart, the uniform fluidized bed spouted bed 2 =50°, the gas phase sprayed into the bed from the side wall opening compensates for the unequal distribution of the airflow by the internal swirl blades, making the gas phase relatively stable and swirling upward near the axis. After the inclination angle decreases, the balance is broken again, causing the particles to accumulate densely on one side of the bed, and the airflow on the other side to blow the particles away. Figure 7 From the pressure distribution cloud diagram, we can see that as the sidewall inclination angle decreases, the pressure in the bottom cone area increases. Figure 8 From the perspective of the overall upward trend, δ 1 =60°, δ 2 =50° The two structures are not much different, but δ 3 =40° bed pressure drop compared to δ 2 =50° increases by 41.5%. Therefore, considering δ 2 =50° is a better solution.

[0076] Fifth, on the axial section Y=0, cases of spouted beds with different structures at time points of t=5s, 5.2s, 5.4s, and 5.6s are selected for comparison, as shown in the solid pressure distribution cloud diagram in Figure 9.

[0077] In Figure 9, the solid pressure is characterized by the difficulty of the solid phase moving with the gas phase. From a global perspective, since the swirl blades change the movement components of the gas phase in all directions, the particle phase of the entire bed is more easily driven by the airflow for circulation and mixing. This not only ensures the reduction of dead zones, but also reduces the residence time of materials in the bed. This is of great significance for certain specific industrial scenarios such as the drying treatment and breeding of some heat-sensitive materials (wheat, rice and other organic materials).

[0078] In summary, the uniform fluidizer of the present invention introduces a swirl effect in the bed layer on the basis of the initial distribution of the inlet gas by the side nozzle, and the internal swirl blades break the obvious boundaries between the injection zone, the annular gap zone and the fountain zone in the traditional spouted bed, and maximize the large-area contact between the gas and solid phases, thereby improving the processing efficiency of the bed material. At the same time, the simple and easy modification does not require too much work, and can be customized on the basis of the original spouted bed to ensure controllable costs. Within the research scope of the present invention, the advantageous structure of the uniform fluidizer is that the angle between the side wall opening and the radial plane is δ=50°, the number of rotations of the swirl blades on the entire bed layer is not easy to be too large, and the flow field is more uniform than others when r=3Q.

[0079] The uniform fluidizer of the present invention is suitable for a spouted bed with a three-dimensional cylindrical cone-shaped basic structure. It can effectively ensure the full mixing of the gas-solid two phases in the injection zone and the annular gap zone, enhance the radial movement of particles in the spouting zone and the annular gap zone, and strengthen the momentum and heat transfer in the annular gap zone. It can not only make up for the inherent defects of the traditional spouted bed, but also reduce the residence time of the material bed, thereby improving the overall efficiency and production capacity of the spouted bed.

Claims

1. A high-efficiency circulating spouted bed, comprising a spouted bed body (1), wherein the spouted bed body (1) is divided into a straight pipe section (101) and a conical pipe section (102) which are connected in an axial direction, the top of the straight pipe section (101) is an air outlet (104), and the bottom of the conical pipe section (102) is provided with an air inlet (103), characterized in that: A uniform fluidizer (2) is arranged in the spouted bed body (1); the fluidizer (2) comprises a jet bucket (201) which is arranged to taper from top to bottom in an axial direction with equal degrees and is open at the top; the jet bucket (201) is installed at the bottom of the spouted bed body (1); the top edge of the jet bucket (201) is sealed in contact with the inner wall of the spouted bed body (1); and the space between the jet bucket (201) and the spouted bed body (1) is a conical annular air inlet channel (3); The angle between the side wall of the air jet bucket (201) and the horizontal plane is 40° to 60°; A main nozzle (202) is provided at the bottom of the jet bucket (201); A plurality of side nozzles (203) are distributed on the side wall of the air jet bucket (201); the plurality of side nozzles (203) are distributed on the side wall of the air jet bucket (201) in a sparse upper portion and dense lower portion, and are divided into three layers: an upper portion, a middle portion, and a lower portion; the number of openings in the same layer in the middle portion is twice the number of openings in the same layer in the upper portion, and the number of openings in the same layer in the lower portion is twice the number of openings in the same layer in the middle portion; The bottom of the jet bucket (201) is also fixed with the bottom end of a swirl blade (204), and the axial center axis of the swirl blade (204) coincides with the axial center axis of the jet bucket (201); the swirl blade (204) is a single-head spiral swirl blade, and the number of rotations of the swirl blade (204) is 3 to 7; the width of the swirl blade (204) is equal to the inner diameter of the main nozzle (202); The top end of the swirl blade (204) is flush with the air outlet (104) at the top of the straight tube section (101), and the axial center axis of the swirl blade (204) coincides with the axial center axis of the straight tube section (101).

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