Low-noise ejector with multi-cavity mixing section

Abstract

The low-noise ejector with the multi-cavity mixing section comprises a suction section, the mixing section and a diffusion section which are sequentially and coaxially arranged in the fluid flowing direction, and a Laval nozzle is coaxially arranged on the inner side of the inlet end of the suction section; a plurality of annular wall surfaces are coaxially arranged in the mixing section at intervals in the fluid flowing direction, the mixing section is divided into an inner cavity and a resonant cavity by the annular wall surfaces, the inner cavity is a mixing section cavity space on the inner sides of the annular wall surfaces, and the resonant cavity is a cavity space formed between the outer sides of the annular wall surfaces and the inner wall of the mixing section. Noise generated by high-speed fluid is reduced through the multi-cavity mixing section, the noise of the ejector can be reduced by 10% or above, and noise pollution of the ejector is reduced.

Description

Technical Field

[0001] The invention belongs to the field of ejectors, and in particular relates to a low-noise ejector with a multi-chamber mixing section. Background Art

[0002] The ejector is a device that uses the negative pressure effect of high-speed fluid to suck and transport gas or liquid. It is widely used in chemical, petroleum, electric power, pharmaceutical and other industries. The ejector is mainly composed of a suction section, a mixing section and a diffuser section. The mixing section is a single-chamber structure. The ejector usually contains a Laval nozzle.

[0003] The noise generated by the ejector during operation will cause environmental and health hazards that cannot be ignored. The noise of the ejector mainly comes from the interaction between the high-speed fluid and the pumped fluid, as well as the turbulent effect of the fluid in the Laval nozzle and mixing chamber. This high-intensity noise creates a harsh working environment, seriously damages the hearing of operators, and affects work efficiency.

[0004] Therefore, the noise reduction research and technological innovation on ejectors have an important engineering application background and are also an inevitable requirement for achieving green manufacturing and building a harmonious environment. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a low-noise ejector with a multi-chamber mixing section, so as to reduce the noise generated by high-speed fluid and reduce the noise pollution of the ejector.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: A low-noise ejector with a multi-chamber mixing section comprises a suction section, a mixing section and a diffuser section which are coaxially arranged in sequence along the flow direction of the fluid, and a Laval nozzle is coaxially arranged inside the inlet end of the suction section; Along the fluid flow direction, a plurality of annular walls are coaxially arranged inside the mixing section at intervals, and the annular walls divide the mixing section into an inner cavity and a resonance cavity. The inner cavity is the cavity space of the mixing section inside the annular wall, and the resonance cavity is the cavity space formed between the outer side of the annular wall and the inner wall of the mixing section.

[0007] Furthermore, the number of the annular walls is 2-50, and they are arranged at equal intervals along the fluid flow direction inside the mixing section (3).

[0008] Furthermore, the number of the annular walls is 8-15.

[0009] Furthermore, the axial length of a single annular wall surface is 0.02-0.5 times the axial length of the mixing section.

[0010] Furthermore, the axial length of the single annular wall surface is 0.06 times the axial length of the mixing section.

[0011] Furthermore, the gap between the two annular wall surfaces is greater than or equal to one half of their axial lengths.

[0012] Furthermore, the annular wall surface is connected to the inner wall of the mixing section through a fixing member.

[0013] Furthermore, the number of fixing members used in each annular wall surface is 4-8.

[0014] Furthermore, the fixing members are evenly arranged along the circumference of the annular wall surface.

[0015] Furthermore, the inner diameter of the annular wall surface is the same as the outlet inner diameter of the suction section.

[0016] Furthermore, the inner diameter of the suction section gradually decreases along the fluid flow direction, the inner diameter of the mixing section remains unchanged along the fluid flow direction, and the inner diameter of the diffuser section gradually increases along the flow direction.

[0017] The low-noise ejector of the present invention divides the mixing section into an inner cavity and a resonance cavity through an annular wall surface, and reduces the noise generated by high-speed fluid through the multi-chamber mixing section. Compared with the ordinary ejector (single-chamber mixing section), the sound pressure level of the ejector of the present invention is significantly reduced, and the ejector noise can be reduced by more than 10%, especially the dominant low-frequency noise is significantly reduced, reducing the noise pollution of the ejector. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings herein are used to provide further explanation of the present invention and constitute a part of this application. The illustrative embodiments of the present invention and their description are used to explain the present invention and do not constitute improper limitations on the present invention.

[0019] Figure 1 It is a schematic diagram of the outer contour structure of the low-noise ejector described in the present invention.

[0020] Figure 2 It is a schematic diagram of the three-dimensional structure of the low-noise ejector described in the present invention.

[0021] Figure 3 It is a cross-sectional view of the low-noise ejector described in the present invention.

[0022] Figure 4 This is a cross-sectional view of the mixing section fixings ( Figure 3 AA view).

[0023] Figure 5 This is a cross-sectional view of the non-fixed parts of the mixing section ( Figure 3 BB view).

[0024] Figure 6It is a noise frequency comparison diagram of a common steam ejector and the low-noise steam ejector of the present invention.

[0025] In the figure: 1-Laval nozzle, 2-suction section, 3-mixing section, 4-diffuser section, 5-annular wall, 6-inner cavity, 7-resonance cavity, 8-high-pressure fluid, 9-low-pressure fluid, 10-fixed part. DETAILED DESCRIPTION

[0026] In order to make those skilled in the art better understand the present invention, the present invention is further clearly and completely described below in conjunction with the accompanying drawings and embodiments. It should be noted that, in the absence of conflict, the features in the embodiments and examples of this application can be combined with each other.

[0027] A typical embodiment of the present invention provides a low-noise ejector with a multi-chamber mixing section, such as Figure 1 , 2 As shown in and 3 , it includes a suction section 2 , a mixing section 3 and a diffuser section 4 .

[0028] The Laval nozzle 1 is located inside the inlet end of the suction section 2 and is arranged coaxially with the suction section 2. Figure 3 As shown, the high-pressure fluid 8 forms a supersonic fluid after passing through the Laval nozzle 1 , and forms a low-pressure area at the outlet of the Laval nozzle 1 , thereby sucking the low-pressure fluid 9 into the suction section 2 from the inlet of the suction section 2 .

[0029] The noise of the ejector mainly comes from the interaction between the high-speed fluid and the pumped fluid, as well as the turbulence effect of the fluid in the nozzle and mixing chamber.

[0030] Based on this, the basic concept of the present invention is to design the mixing section 3 as a multi-chamber, that is, along the fluid flow direction, the mixing section 3 is provided with a plurality of annular walls 5 coaxially spaced inside, and the annular walls 5 divide the mixing section 3 into an inner cavity 6 and a resonance cavity 7, wherein the inner cavity 6 is the cavity space of the mixing section inside the annular wall 5, and the resonance cavity 7 is the cavity space formed between the outer side of the annular wall 5 and the inner wall of the mixing section 3. When the high-speed fluid 8 passes through the multi-chamber mixing section, the high-pressure fluid 8 generates eddy currents at the annular wall 5 to dissipate the kinetic energy of the fluid; at the same time, the sound waves generated by the high-speed fluid are continuously reflected and interfered between the chambers when passing through the inner cavity 6 and the resonance cavity 7, so that the sound wave energies cancel each other out, thereby achieving a noise reduction effect.

[0031] More specifically, Figure 3 As shown, the suction section 2, the mixing section 3, and the diffuser section 4 are coaxially arranged in sequence along the fluid flow direction. The inner diameter of the Laval nozzle 1 first decreases and then increases along the flow direction, the inner diameter of the suction section 2 gradually decreases along the flow direction, the inner diameter of the mixing section 3 remains unchanged along the flow direction, and the inner diameter of the diffuser section 4 gradually increases along the flow direction.

[0032] In a preferred embodiment, the number of the annular walls 5 is 2-50, for example: 2, 5, 8, 10, 15, 20, 30, 40, 50, etc., which are arranged at equal intervals along the fluid flow direction inside the mixing section 3. Every time the fluid in the mixing section 3 passes through an annular wall 5, a vortex is generated to reduce the fluid velocity. At the same time, due to the interaction of sound waves between chambers, a noise reduction effect is achieved. The number of annular walls 5 increases with the growth of the mixing section 3, but for a certain mixing section 3, after the number of annular walls 5 increases to a certain number, the noise reduction effect is not obvious if the number is increased further.

[0033] In a preferred embodiment, the axial length of a single annular wall surface 5 is 0.02-0.5 times the axial length of the mixing section 3, for example: 0.02 times, 0.06 times, 0.1 times, 0.2 times, 0.3 times, 0.4 times, 0.5 times, etc. If a single annular wall surface 5 is too long, the disturbance to the fluid flow is small, the vortex is small, and at the same time, the number of annular walls 5 set within a certain length of the mixing section 3 is small, and the noise reduction effect cannot be achieved. It should be noted that the product of the axial length of a single annular wall surface 5 and the number of annular walls 5 should be less than the axial length of the mixing section 3, and the gap between every two annular walls should not be greater than their axial length.

[0034] A relatively specific embodiment provides a connection method between the annular wall 5 and the mixing section 3. Figure 3 and Figure 4 As shown, the annular wall surface 5 is connected to the inner wall of the mixing section 3 through a fixing piece 10. In order to firmly fix the annular wall surface 5 to the inner wall of the mixing section 3, the number of fixing pieces 10 used in each annular wall surface 5 is 4-8, and the fixing pieces 10 are evenly arranged along the circumference of the annular wall surface 5.

[0035] In this embodiment, the shape of the fixing member 10 can be a cylindrical structure or a square structure. The fixing member 10 is connected to the mixing section 3 and the annular wall surface 5 by welding or bolting.

[0036] The following is a relatively specific embodiment to further clarify and fully illustrate the technical solution claimed in the present invention.

[0037] In this embodiment, the high-pressure steam parameters are: pressure 20.0 MPa, temperature 566° C., mass flow rate 69.4 kg / s; the low-pressure steam parameters are: pressure 3.9 MPa, temperature 340° C., mass flow rate 69.4 kg / s.

[0038] The diameter of the mixing section 3 is 169 mm, the outlet diameter of the diffuser section 4 is 372 mm, the axial length of the mixing section 3 is 1183 mm, and the axial length of the diffuser section 4 is 1322 mm.

[0039] The number of annular walls 5 is 15, the inner diameter of the annular wall 5 is 109 mm, the radial length of the annular wall 5 is 25.5 mm, and the spacing between the annular walls 5 is 25 mm. The number of fixing members 10 is 4, which are evenly arranged along the circumference of the annular wall 5. The shape of the fixing member 10 is a cylindrical structure, and the fixing member 10 is used to fix the annular wall 5 to the inner wall of the mixing section 3. The depth of the resonance cavity 7 is 10 mm, and the length of the resonance cavity 7 is 1125 mm.

[0040] Using the above-mentioned low-noise ejector, the high-pressure fluid 8 as the working fluid becomes a supersonic fluid after passing through the Laval nozzle 1: after the supersonic fluid is ejected from the Laval nozzle 1, when passing through the multi-chamber mixing section, the high-speed fluid generates a vortex at the annular wall 5, so that the kinetic energy of the high-speed fluid can be dissipated. At the same time, the multi-chamber structure provides a complex propagation path for the sound waves generated by the high-speed fluid. When the sound waves pass through multiple chambers and perforations, they will continuously reflect and interfere between the chambers. The reflection and interference cause the sound wave energy to cancel each other out, thereby reducing noise. The supersonic fluid and the low-speed fluid 9 are evenly mixed in the suction section 2 and the mixing section 3 and then enter the diffuser section 4, and the mixed fluid is discharged from the outlet of the diffuser section 4.

[0041] The sound pressure level at 2 meters away from the centerline outlet of the steam ejector is monitored through numerical simulation. Figure 6 The figure shows the noise frequency comparison between ordinary steam ejector and low noise steam ejector. Figure 6 It can be seen that compared with the ordinary steam ejector (single-chamber mixing section), the sound pressure level of the low-noise ejector (multi-chamber mixing section) provided by the present invention is reduced from 137.2dB to 122.6dB, with a reduction of up to 10.6%.

[0042] The scope of protection claimed by the present invention is not limited to the above specific embodiments. For those skilled in the art, the present invention may have various deformations and changes. Any modifications, improvements and equivalent substitutions made within the concept and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-noise ejector with a multi-chamber mixing section, comprising a suction section, a mixing section and a diffuser section coaxially arranged in sequence along the flow direction of the fluid, wherein a Laval nozzle is coaxially arranged inside the inlet end of the suction section; characterized in that: Along the fluid flow direction, a plurality of annular walls are coaxially arranged inside the mixing section at intervals, and the annular walls divide the mixing section into an inner cavity and a resonance cavity. The inner cavity is the cavity space of the mixing section inside the annular wall, and the resonance cavity is the cavity space formed between the outer side of the annular wall and the inner wall of the mixing section.

2. The low noise ejector with a multi-chamber mixing section according to claim 1, characterized in that: The number of the annular walls is 2-50, and they are arranged at equal intervals along the fluid flow direction inside the mixing section.

3. The low noise ejector with a multi-chamber mixing section according to claim 2, characterized in that: The number of the annular walls is 8-15.

4. The low noise ejector with a multi-chamber mixing section according to claim 1 or 3, characterized in that: The axial length of a single annular wall surface is 0.02-0.5 times the axial length of the mixing section.

5. The low noise ejector with a multi-chamber mixing section according to claim 4, characterized in that: The axial length of the single annular wall surface is 0.06 times the axial length of the mixing section.

6. The low noise ejector with a multi-chamber mixing section according to claim 2 or 5, characterized in that: , the gap between the two annular walls is greater than or equal to half of the axial length of the annular walls.

7. The low noise ejector with a multi-chamber mixing section according to claim 6, characterized in that: The annular wall surface is connected to the inner wall of the mixing section through a fixing piece.

8. The low noise ejector with a multi-chamber mixing section according to claim 7, characterized in that: The number of fixing members used on each annular wall surface is 4-8.

9. The low noise ejector with a multi-chamber mixing section according to claim 8, characterized in that: The fixing parts are evenly arranged along the circumference of the annular wall surface.

10. The low noise ejector with a multi-chamber mixing section according to claim 1 or 9, characterized in that: The inner diameter of the annular wall is the same as the outlet inner diameter of the suction section.

11. The low noise ejector with a multi-chamber mixing section according to claim 10, characterized in that: The inner diameter of the suction section gradually decreases along the fluid flow direction, the inner diameter of the mixing section remains unchanged along the fluid flow direction, and the inner diameter of the diffuser section gradually increases along the flow direction.

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