CN112855629A

CN112855629A - Gas ejector

Info

Publication number: CN112855629A
Application number: CN202110239774.XA
Authority: CN
Inventors: 郭孝国
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-03-04
Filing date: 2021-03-04
Publication date: 2021-05-28

Abstract

The invention aims to solve the problem that the structure of a nozzle and a throat section needs to be redesigned and manufactured again when the area ratio of the existing ejector is changed, and provides a gas ejector, which comprises a suction chamber, a diffusion outer cylinder and an exhaust tail pipe which are communicated in sequence and are coaxial; the diffusion outer cylinder comprises a mixing part, a contraction part, a throat part and an expansion part; the annular spray pipe is fixedly arranged in the suction chamber, the diffusion cone is fixedly arranged in the diffusion outer barrel and comprises a conical first cone section, a conical second cone section and a conical third cone section, the conical first cone section, the conical second cone section and the conical third cone section are sequentially and coaxially connected, the diffusion cone is coaxial with the diffusion outer barrel, the bottom of the conical first cone section is connected with the upper bottom of the conical second cone section, the lower bottom of the conical second cone section is connected with the lower bottom of the conical third cone section, the conical first cone section is positioned in the contraction part, the conical second cone section is positioned in the throat part, the conical third cone section is positioned in the expansion part, and the outer profile of the conical second cone section is parallel to the inner wall of the throat part.

Description

Gas ejector

Technical Field

The invention relates to the field of vacuumizing refrigeration, in particular to a gas ejector.

Background

The ejector is widely applied in industrial production departments, and industries such as mechanical manufacturing, light industry, chemical industry, textile and the like, whether in operation or economic technology comparison, are convenient to use and applicable, and are economical and reasonable. In the occasions of refrigeration and vacuum pumping, the compressor, the mechanical vacuum pump and the like can be replaced. In addition, because the quick-wear spare parts are not needed, the operation is reliable, the service life is long, especially in some occasions, air and steam are used as media, the structure is simple, the manufacturing cost is low, the operation, the use and the maintenance are simple, especially in some industrial production, the comprehensive utilization of waste heat and waste gas is reasonably utilized, and the economic significance is greater.

The ejector on the market at present is single in design form, the fixed structure of the ejector can not be adjusted, when the performance requirement of the ejector changes, the main structure of the ejector needs to be redesigned and manufactured, for example, under certain conditions, only the parameter of the area ratio of the flow area of the throat section to the flow area of the nozzle throat needs to be changed, but the structures of the nozzle and the throat section need to be redesigned and manufactured, the production and the manufacture are troublesome, although some students research the nozzle flow adjusting structure of the ejector, for example, the ejector with the nozzle flow adjusting needle, the operation limitation is limited, and the popularization is difficult in the aspect of use.

Disclosure of Invention

The invention aims to provide a gas ejector, aiming at the problem that the existing ejector needs to redesign and manufacture the structures of a nozzle and a throat section when the area ratio of the flow area of the throat section to the flow area of the nozzle throat is changed.

The technical purpose of the invention is realized by the following technical scheme:

a gas ejector comprises a suction chamber, a diffusion outer cylinder and a tail pipe which are sequentially communicated in a sealing way and are coaxially arranged; the diffusion outer cylinder comprises a mixing part with a constant pipe diameter, a contraction part with a gradually narrowed pipe diameter, a throat part with a gradually enlarged pipe diameter and an expansion part with a gradually enlarged pipe diameter; the annular spray pipe is fixedly arranged in the suction chamber, the annular spray pipe is coaxial with the suction chamber, one end of the annular spray pipe, facing the tail pipe, is provided with an annular nozzle which is coaxial with the body of the annular spray pipe, and part of the nozzles of the annular spray pipe extend into the diffusion outer cylinder; a jet flow air inlet pipe communicated with the annular spray pipe and the external environment is fixedly arranged on the suction chamber; the diffusion cone is fixedly arranged in the diffusion outer barrel and comprises a first conical section, a second conical section and a third conical section, the first conical section, the second conical section and the third conical section are sequentially and coaxially connected, the diffusion cone is coaxially arranged with the diffusion outer barrel, the bottom of the first conical section is connected with the upper bottom of the second conical section, the lower bottom of the second conical section is connected with the lower bottom of the third conical section, the taper of the second conical section is smaller than that of the first conical section, the first conical section is located in the contraction portion, the second conical section is located in the throat portion, the third conical section is located in the expansion portion, and the outer profile of the second conical section is parallel to the inner wall of the throat portion.

Preferably, a cylindrical connecting table is fixedly arranged at one end, away from the conical section II, of the conical section III, a positioning seat is fixedly arranged at the junction of the diffusion outer cylinder and the exhaust tail pipe, a positioning hole matched with the connecting table is formed in the positioning seat, and the connecting table is arranged in the positioning hole and fixed with the positioning seat.

Preferably, one end of the connecting platform, which is far away from the diffusion cone, is provided with a flow guide cone, and the tip of the flow guide cone faces back to the diffusion outer cylinder.

Preferably, the positioning seat comprises a circular plate body and a cylindrical seat body, the seat body is coaxial with the plate body, the seat body is fixedly arranged in the center of the plate body, the plate body is fixed between the diffusion outer cylinder and the exhaust tail pipe, the positioning hole is formed in the seat body, a plurality of through holes are formed in the plate body, and the through holes are evenly distributed in a circumferential mode by taking the axis of the plate body as the center.

Preferably, the diffuser cone is a hollow structure.

The preferred, annular nozzle includes spray tube outer wall and spray tube inner wall and efflux intake pipe, and spray tube outer wall and spray tube inner wall are the cast, and the spray tube outer wall cover is established outside the spray tube inner wall, draws fluid suction pipe's one end spray tube outer wall and spray tube inner wall sealing connection at annular nozzle orientation, leaves the gap formation nozzle between annular nozzle towards tail pipe's one end spray tube outer wall and spray tube inner wall.

Preferably, the outer wall of the spray pipe comprises a conical outer shunt part, a straight pipe outer connecting part and an outer nozzle part, the outer nozzle part is a pipe with the middle part bulging outwards, the outer shunt part, the outer connecting part and the outer nozzle part are sequentially connected, the inner wall of the spray pipe comprises a conical inner shunt part, a straight pipe inner connecting part and an inner nozzle part, the inner nozzle part is a pipe with the middle part sunken inwards, and the inner shunt part, the inner connecting part and the inner nozzle part are sequentially connected; the outer shunt part and the inner shunt part are arranged oppositely and far away from one end of the connecting part to be intersected, the outer connecting part and the inner connecting part are arranged oppositely, the outer nozzle part and the inner nozzle part are arranged oppositely, and the concave position of the outer nozzle part is opposite to the convex position of the inner nozzle part.

Preferably, the suction chamber and the tail pipe are respectively provided with a flange plate at one end facing the diffusion outer cylinder and at two ends of the diffusion outer cylinder, and the suction chamber, the diffusion outer cylinder and the tail pipe are sequentially connected through the flange plates.

Preferably, the inlet end of the suction chamber is provided with an ejection fluid suction nozzle, and a port of the ejection fluid suction nozzle is provided with a flange plate.

Preferably, the number of the jet flow air inlet pipes is 2, 3 or 4, and the jet flow air inlet pipes are uniformly distributed on the circumference by taking the axis of the outer wall of the spray pipe as the center. The invention has the following beneficial effects:

the invention is provided with the reducing diffusion outer cylinder and the diffusion cone, and a gas channel with a contraction section, a throat section and an expansion section is formed between the diffusion outer cylinder and the diffusion cone, so the structure is compact. The outer profile of the second conical section is parallel to the inner wall of the corresponding diffusion outer cylinder, so that the size of the throat section of the gas channel can be changed by moving the diffusion cone along the axial direction. Because the size of the annular nozzle does not change when the diffuser cone is moved axially, the area ratio of the throat section to the nozzle throat can be changed by moving the adjusting core body. Therefore, the same parts can be adopted during production and processing, the design requirements can be met only by changing the installation position of the diffusion cone or only changing the size of the diffusion cone, the universality of the parts is improved, the working state is more easily ensured to be close to the design working point, and the efficiency of the ejector is improved; and the structure is simple, the processing and the manufacturing are easy, and the installation is convenient.

Drawings

FIG. 1 is a schematic diagram of a gas eductor;

FIG. 2 is a schematic structural view of a jet inlet duct of the gas eductor;

FIG. 3 is a schematic view of a gas eductor for drawing fluid;

FIG. 4 is a schematic view of the structure of the suction chamber of the gas eductor;

FIG. 5 is a schematic structural view of a supersonic gas eductor annular nozzle;

FIG. 6 is a schematic structural view of the inner wall of the nozzle;

FIG. 7 is a schematic structural view of the outer wall of the nozzle;

FIG. 8 is a schematic structural view of a diffusion outer cylinder of the gas ejector;

FIG. 9 is a schematic view of the diffuser cone of the gas eductor;

FIG. 10 is a front view of a positioning socket of the gas injector;

FIG. 11 is a right side view of the positioning socket of the gas eductor;

fig. 12 is a schematic structural view of a gas eductor tailpipe.

Reference number specification, 1, jet inlet pipe; 2. an ejector fluid suction nozzle; 3. a suction chamber; 4. an annular nozzle; 41. the inner wall of the spray pipe; 411. an inner flow-splitting section; 412. an inner connection portion; 413. an inner nozzle portion; 42. the outer wall of the spray pipe; 421. an outer flow-splitting section; 422. an outer connecting portion; 423. an outer nozzle portion; 5. a diffusion outer cylinder; 51. a connecting section; 52. a contraction section; 53. a throat section; 54. an expansion section; 6. a diffuser cone; 61. a first conical section; 62. a second conical section; 63. a cone section III; 64. a connecting table; 65. a flow guide cone; 7. positioning seats; 71. a plate body; 72. a base body; 8. and a tail pipe.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings. In which like parts are designated by like reference numerals.

A gas ejector, as shown in figure 1, comprises a suction chamber 3, a diffusion outer cylinder 5, a tail pipe 8, an annular nozzle 4 and a diffusion cone 6. The suction chamber 3, the diffusion outer cylinder 5 and the tail pipe 8 are sequentially communicated in a sealing manner and are coaxially arranged. The annular nozzle 4 is arranged in the suction chamber 3 and is coaxial with the suction chamber 3, as shown in fig. 2 and 5, the annular nozzle 4 is communicated with a jet inlet pipe 1 extending out of the suction chamber 3, an annular nozzle coaxial with the body of the annular nozzle 4 is arranged at one end of the annular nozzle 4 facing the tail pipe 8, and part of the nozzle of the annular nozzle 4 extends into the diffusion outer cylinder 5. The diffusion cone 6 is arranged in the diffusion outer cylinder 5, and a diffusion channel for gas to pass through is formed between the inner wall of the diffusion outer cylinder 5 and the outer profile of the diffusion cone 6.

Referring to fig. 1, 3 and 4, the suction chamber 3 is substantially a straight tube, and the inlet end of the suction chamber is provided with an ejection fluid suction nozzle 2, and a flange is provided at the port of the ejection fluid suction nozzle 2 for connecting with an air supply device. The outlet end of the suction chamber 3 is provided with a flange for connection with the diffuser outer cylinder 5.

As shown in fig. 5-7, for convenience of processing, improving the processing precision of the nozzle and improving the smoothness of the fluid contact surface, the annular nozzle 4 is split, the annular nozzle 4 includes a nozzle outer wall 42, a nozzle inner wall 41 and a jet intake pipe 1, the nozzle outer wall 42 and the nozzle inner wall 41 are both of a pipe type, the nozzle outer wall 42 is sleeved outside the nozzle inner wall 41, the nozzle outer wall 42 and the nozzle inner wall 41 are connected by an O-ring or a welding seal at one end of the annular nozzle 4 facing away from the tail pipe 8, and a gap is left between the nozzle outer wall 42 and the nozzle inner wall 41 at one end of the annular nozzle 4 facing the tail pipe 8 to form a nozzle. Specifically, as shown in fig. 7, the nozzle outer wall 42 includes a conical outer branch portion 421, a straight-tube outer connecting portion 422, and an outer nozzle portion 423, the outer nozzle portion 423 is a tube type with a middle portion bulging outward, the outer branch portion 421, the outer connecting portion 422, and the outer nozzle portion 423 are sequentially connected, and one end of the outer branch portion 421 with a larger diameter is connected to the outer connecting portion 422. As shown in fig. 6, the nozzle inner wall 41 includes a conical inner branch portion 411, a straight-tube inner connecting portion 412 and an inner nozzle portion 413, the inner nozzle portion 413 is a tube type with a central portion recessed inwards, the inner branch portion 411, the inner connecting portion 412 and the inner nozzle portion 413 are connected in sequence, and one end of the inner branch portion 411 with a smaller diameter is connected to the inner connecting portion 412. The outer shunt part 421 and the inner shunt part 411 are oppositely arranged and far away from one end of the connecting part to intersect to form a tip, so that the effect of reducing resistance can be achieved when the injection flow passes through. The outer connecting portion 422 is opposite to the inner connecting portion 412, and a through hole for communicating the jet flow air inlet pipe 1 is formed in the outer connecting portion 422. The outer nozzle part 423 is arranged opposite to the inner nozzle part 413, and a nozzle structure with an outlet which is narrowed first and then expanded is formed at the concave position of the outer nozzle part 423 and opposite to the convex position of the inner nozzle part 413. The jet pipe air inlet pipe is hermetically connected with the outer wall 42 of the jet pipe at a through hole, the suction chamber 3 is provided with a through hole for the jet flow air inlet pipe 1 to pass through, the outer wall of the jet flow air inlet pipe 1 is hermetically connected with the inner wall of the through hole on the suction chamber 3, and the jet flow air inlet pipe 1 is fixedly connected with the annular jet pipe 4 and the suction chamber 3; in order to comprehensively consider the problems of common intake air flow and stress balance, 2, 3 or 4 jet inlet pipes 1 are preferably arranged, 3 are preferably arranged in the embodiment, and the jet inlet pipes 1 are uniformly distributed on the circumference by taking the axis of the outer wall 42 of the nozzle as the center. In order to reduce the resistance of the injection flow passing through the jet flow inlet pipe 1, the part of the jet flow inlet pipe 1 in the suction chamber 3 is designed into a shape which is in accordance with the flow resistance reduction, and can be set into a round shape, a diamond shape or a flat oval shape.

As shown in fig. 8, the diffusion outer cylinder 5 is substantially tubular, and the diffusion outer cylinder 5 is divided into a mixing portion, a contraction portion, a throat portion and an expansion portion, which are sequentially arranged, wherein the mixing portion is a straight pipe with a uniform pipe diameter, the contraction portion is a pipe with a pipe diameter gradually narrowing from an inlet to an outlet, the throat portion is a pipe with a pipe diameter gradually increasing from the inlet to the outlet, and the expansion portion is a pipe with a pipe diameter gradually increasing from the inlet to the outlet. Flanges for connecting the suction chamber 3 and the tail pipe 8 are provided at both ends of the diffuser outer cylinder 5, respectively. As shown in fig. 9, the diffuser cone 6 includes a first conical section 61, a second conical section 62 and a third conical section 63, the first conical section 61, the second conical section 62 and the third conical section 63 are sequentially and coaxially connected, the diffuser cone 6 and the diffuser outer cylinder 5 are coaxially arranged, the bottom of the first conical section 61 is connected with the upper bottom of the second conical section 62, the lower bottom of the second conical section 62 is connected with the lower bottom of the third conical section 63, and the taper of the second conical section 62 is smaller than that of the first conical section 61. As shown in fig. 1, the first tapered section 61 is located in the constriction, the diameter of the first tapered section 61 is gradually increased in the constriction, and the inner diameter of the constriction is gradually decreased, so that the gas passage in the constriction is gradually narrowed, and a narrowed section required for the gas diffusion of the ejector is formed. The second conical section 62 is located in the throat part, and the outer profile of the second conical section 62 is parallel to the inner wall of the throat part, so that the width of the gas channel in the throat part is basically unchanged and basically consistent with the narrowest part of the narrowing section, and the throat section required by gas diffusion of the ejector is formed. The third conical section 63 is located in the expansion part, the diameter of the third conical section 63 is gradually reduced, the pipe diameter of the diffusion part is gradually increased, the gas channel is in a continuous expansion shape, and the expansion section 54 required by the diffusion of the ejector is formed. Because the outer profile of the second cone section 62 is parallel to the inner wall of the throat part, the size of the throat section of the gas channel can be changed by only moving the diffuser cone 6 along the axial direction, as shown in fig. 1, when the diffuser cone 6 moves upwards, the flow area of the throat section becomes small, and when the diffuser cone 6 moves downwards, the flow area of the throat section becomes large. Because the size of the nozzle of the annular nozzle 4 cannot be changed when the diffusion cone 6 is moved along the axial direction, the area ratio of the throat section to the nozzle throat can be changed only by moving the adjusting core body; therefore, the same parts can be adopted during production and processing, the design requirements can be met only by changing the installation position of the diffuser cone 6 or only changing the size of the diffuser cone 6, the universality of the parts is improved, and the structure is simple. In order to reduce the weight of the adjusting core body and reduce the processing difficulty, the adjusting core body is preferably set to be a hollow structure.

As shown in fig. 9, a cylindrical connecting platform 64 is fixedly arranged at one end of the third conical section 63 away from the second conical section 62. As shown in fig. 1, a positioning seat 7 is fixedly disposed at a junction between the diffusion outer cylinder 5 and the tail pipe 8, and as shown in fig. 10 and 11, the positioning seat 7 includes a circular plate body 71 and a cylindrical seat body 72, a positioning hole adapted to the connection table 64 is disposed on the seat body 72, the connection table 64 is disposed in the positioning hole and fixed to the positioning seat 7, and the relative position of the diffusion cone 6 and the diffusion outer cylinder 5 can be adjusted by changing the axial position of the connection table 64 on the positioning seat 7 during installation. The fixed center that sets up at plate body 71 of pedestal 72, plate body 71 are fixed between diffusion urceolus 5 and tail pipe 8, are provided with a plurality of clearing holes that are used for gaseous to pass through on the plate body 71, and these clearing holes use plate body 71 axis to distribute as the even circumference in center, under the prerequisite that intensity satisfies the requirement, obtain great flow area as far as, 8 have been seted up to the clearing hole in this embodiment. One end of the connecting platform 64 far away from the diffuser cone 6 is provided with a flow guide cone 65, and the tip of the flow guide cone 65 faces away from the diffuser outer cylinder 5 and is used for guiding the gas flowing out of the annular channel to be converged.

As shown in fig. 12, the exhaust tail section is a section of reducing pipe, and the front part of the exhaust tail section is fixedly provided with a flange plate for connecting the diffusion outer cylinder 5.

When the jet flow type low-energy and low-pressure gas ejector is used, low-energy and low-pressure gas to be ejected enters the suction chamber 3 from the jet flow suction nozzle 2, the flow speed and pressure of the gas flow are stabilized in the suction pipe, high-pressure and high-energy jet flow gas enters the annular nozzle 4 from the jet flow inlet pipe 1 and is ejected from the nozzle of the annular nozzle, the jet flow gas and the gas to be ejected are mixed in a mixing section of the suction chamber 3 and the diffusion outer barrel 5, the mixed gas flow enters a gas flow passage between the diffusion outer barrel 5 and the diffusion cone 6 to realize speed reduction and pressurization, the mixed gas flow is changed from supersonic velocity to subsonic velocity, and is further subjected to speed reduction and diffusion, and finally is discharged out of the ejector from.

While the conception and examples according to the present invention have been described in detail, it should be understood that various changes, substitutions and alterations can be made therein without departing from the spirit and scope of the invention.

Claims

1. A gas ejector is characterized in that: comprises a suction chamber (3), a diffusion outer cylinder (5) and a tail pipe (8) which are sequentially communicated in a sealing way and are coaxially arranged; the diffusion outer cylinder (5) comprises a mixing part with a constant pipe diameter, a contraction part with a gradually narrowed pipe diameter, a throat part with a gradually enlarged pipe diameter and an expansion part with a gradually enlarged pipe diameter; the suction chamber (3) is fixedly provided with an annular spray pipe (4), the annular spray pipe (4) is coaxial with the suction chamber (3), one end of the annular spray pipe (4) facing the tail pipe (8) is provided with an annular nozzle which is coaxial with the body of the annular spray pipe, and part of the nozzle of the annular spray pipe (4) extends into the diffusion outer cylinder (5); a jet flow air inlet pipe (1) communicated with the annular spray pipe (4) and the external environment is fixedly arranged on the suction chamber (3); the diffusion cone (6) is fixedly arranged in the diffusion outer cylinder (5), the diffusion cone (6) comprises a conical first cone section (61), a conical second cone section (62) and a conical third cone section (63), the conical first cone section (61), the conical second cone section (62) and the conical third cone section (63) are sequentially and coaxially connected, the diffusion cone (6) and the diffusion outer cylinder (5) are coaxially arranged, the bottom of the conical first cone section (61) is connected with the upper bottom of the conical second cone section (62), the lower bottom of the conical second cone section (62) is connected with the lower bottom of the conical third cone section (63), the taper of the conical second cone section (62) is smaller than that of the conical first cone section (61), the conical first cone section (61) is located in the contraction part, the conical second cone section (62) is located in the throat part, the conical third cone section (63) is located in the expansion part, and the outer shape surface of the conical second cone section (62) is parallel to the inner wall of the throat part.

2. The gas eductor of claim 1 wherein: one end, far away from the second conical section (62), of the third conical section (63) is fixedly provided with a cylindrical connecting table (64), a positioning seat (7) is fixedly arranged at the junction of the diffusion outer cylinder (5) and the tail pipe (8), a positioning hole matched with the connecting table (64) is formed in the positioning seat (7), and the connecting table (64) is arranged in the positioning hole and fixed with the positioning seat (7).

3. The gas eductor of claim 2 wherein: one end, far away from the diffusion cone (6), of the connecting table (64) is provided with a flow guide cone (65), and the tip of the flow guide cone (65) faces back to the diffusion outer cylinder (5).

4. The gas eductor of claim 2 wherein: positioning seat (7) are including circular shape plate body (71) and columniform pedestal (72), pedestal (72) are coaxial with plate body (71), and fixed the setting in the center of plate body (71) in pedestal (72), and plate body (71) are fixed between diffusion urceolus (5) and tail pipe (8), and the locating hole is seted up on pedestal (72), is provided with a plurality of clearing holes on plate body (71), the clearing hole uses plate body (71) axis to distribute as the even circumference in center.

5. The gas eductor of claim 1 wherein: the diffusion cone (6) is of a hollow structure.

6. The gas eductor of claim 1 wherein: annular spray pipe (4) are including spray pipe outer wall (42) and spray pipe inner wall (41) and efflux intake pipe (1), spray pipe outer wall (42) and spray pipe inner wall (41) are the cast, spray pipe outer wall (42) cover is established outside spray pipe inner wall (41), draw fluid suction tube's one end spray pipe outer wall (42) and spray pipe inner wall (41) sealing connection towards annular spray pipe (4), leave the gap formation nozzle between annular spray pipe (4) one end spray pipe outer wall (42) and spray pipe inner wall (41) towards tail pipe (8).

7. The gas eductor of claim 6 wherein: the outer wall (42) of the spray pipe comprises a conical outer shunt part (421), a straight pipe outer connecting part (422) and an outer nozzle part (423), the outer nozzle part (423) is a pipe type with the middle part bulging outwards, the outer shunt part (421), the outer connecting part (422) and the outer nozzle part (423) are sequentially connected, the inner wall (41) of the spray pipe comprises a conical inner shunt part (411), a straight pipe inner connecting part (412) and an inner nozzle part (413), the inner nozzle part (413) is a pipe type with the middle part sunken inwards, and the inner shunt part (411), the inner connecting part (412) and the inner nozzle part (413) are sequentially connected; the outer shunt part (421) and the inner shunt part (411) are arranged oppositely and far away from one end of the connecting part to intersect, the outer connecting part (422) and the inner connecting part (412) are arranged oppositely, the outer nozzle part (423) and the inner nozzle part (413) are arranged oppositely, and the concave position of the outer nozzle part (423) is opposite to the convex position of the inner nozzle part (413).

8. The gas eductor of claim 1 wherein: the suction chamber (3) and the tail pipe (8) are respectively provided with a flange plate at one end facing the diffusion outer cylinder (5) and at two ends of the diffusion outer cylinder (5), and the suction chamber (3), the diffusion outer cylinder (5) and the tail pipe (8) are sequentially connected through the flange plates.

9. The gas eductor of claim 1 wherein: an injection fluid suction nozzle (2) is arranged at the inlet end of the suction chamber (3), and a flange plate is arranged at the port of the injection fluid suction nozzle (2).

10. The gas eductor of claim 1 wherein: the number of the jet flow air inlet pipes (1) is 2, 3 or 4, and the jet flow air inlet pipes (1) are uniformly distributed on the circumference by taking the axis of the outer wall (42) of the spray pipe as the center.