Nested structure two-stage liquid ring pump

Abstract

This invention belongs to the field of liquid displacement mechanical technology, specifically relating to a nested two-stage liquid ring pump, including a housing. A primary impeller and a secondary impeller are housed within the housing, with the secondary impeller nested outside the primary impeller, forming a primary pump chamber between them. A motor is mounted on one side of the housing, and a drive gear is fixedly mounted on the motor's output shaft. The drive gear is sequentially connected to the secondary impeller via a primary transmission gear and a secondary transmission gear. An end cover is located at the end of the housing furthest from the motor, and a distribution plate is positioned between the end cover and the housing. The distribution plate has a primary pump chamber intake port, a primary pump chamber exhaust port, a secondary pump chamber intake port, and a secondary pump chamber exhaust port. Several stiffening plates are installed inside the end cover. This device can reduce flow resistance and energy loss, and eliminate shaft backflow.

Description

Technical Field

[0001] This invention belongs to the field of liquid displacement mechanical technology, specifically relating to a nested two-stage liquid ring pump. Background Technology

[0002] Liquid ring pumps, as fluid machines that rely on a working fluid to form a liquid ring for gas compression and transport, are widely used in industry due to their simple structure, stable operation, and wide applicability. However, the performance of traditional single-stage liquid ring pumps is significantly limited by the liquid ring linear velocity and the physicochemical properties of the working fluid. The liquid ring linear velocity directly affects the energy transfer efficiency within the pump, while the viscosity, saturated vapor pressure, and other physicochemical properties of the working fluid limit its adaptability under different operating conditions. This results in a relatively limited compression ratio and efficient operating range for single-stage liquid ring pumps, making it difficult to meet the stringent requirements of high vacuum or high compression efficiency in applications. To overcome the performance bottleneck of single-stage liquid ring pumps, two-stage liquid ring pumps have been developed and put into application. Two-stage liquid ring pumps perform staged compression of gas through two series-connected compression chambers, dividing the gas compression process into two stages. By rationally allocating the compression ratio between the two stages, the overall compression ratio can be effectively improved, while simultaneously expanding the efficient operating range.

[0003] Chinese patent CN109667759A discloses a two-stage liquid ring vacuum pump and its assembly method. It features two compression chambers, eliminating the need for gas channels on the intermediate wall and directly connecting the two chambers via an external connecting pipe. This simplifies the assembly process, improves efficiency, and enhances performance and safety stability while maintaining pumping capacity and vacuum level. Compared to traditional two-stage pumps, it significantly reduces production noise and noise pollution. However, the pump chambers of the first and second stages, along with the impellers, are axially connected in series, resulting in a long fluid travel distance between the two stages. This typically requires external piping for interstage flow, leading to increased flow resistance and higher energy loss. Furthermore, the shaft penetration between the first and second stage pump chambers makes backflow at the shaft hole unavoidable. The coaxial synchronous rotation of the first and second stage impellers results in a relatively fixed interstage compression ratio, lacking adaptability to different operating conditions and making it difficult to maintain both high efficiency and high compression capacity across a wide operating range. Summary of the Invention

[0004] The purpose of this invention is to provide a nested two-stage liquid ring pump that can reduce flow resistance and energy loss, avoid the shaft hole gap caused by the shaft passing through the two-stage cavity in the traditional axial series structure, and at the same time improve the stability of equipment operation and reduce operating noise.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] The nested two-stage liquid ring pump of the present invention includes a housing, within which a primary impeller and a secondary impeller are disposed. The secondary impeller is nested outside the primary impeller, forming a primary pump chamber between the secondary impeller and the primary impeller, and a secondary pump chamber between the housing and the secondary impeller. The eccentricity direction of the primary impeller relative to the primary pump chamber is opposite to that of the secondary impeller relative to the secondary pump chamber. A motor is disposed on one side of the housing, and the output shaft of the motor is coaxially and fixedly connected to the primary impeller. A drive gear is also fixedly disposed on the output shaft of the motor. The drive gear is sequentially connected to the secondary impeller through a primary transmission gear and a secondary transmission gear. An end cover is disposed at the end of the housing away from the motor. A distribution plate is disposed between the end cover and the housing. The distribution plate is provided with a primary pump chamber intake port, a primary pump chamber exhaust port, a secondary pump chamber intake port, and a secondary pump chamber exhaust port. Several ribs are disposed inside the end cover, and the ribs and the inner wall of the end cover enclose an interstage connecting channel, an intake channel, and an exhaust channel.

[0007] Furthermore, the secondary transmission gear meshes with the internal gear ring fixed inside the secondary impeller.

[0008] Furthermore, the distribution plate is arranged in a circular shape.

[0009] Furthermore, the end cap is provided with an air intake port and an air exhaust port, with the air intake port connected to the air intake channel and the air exhaust port connected to the air exhaust channel.

[0010] Furthermore, the intake passage is adjacent to the interstage combined passage and the exhaust passage, respectively, and the interstage combined passage is adjacent to the exhaust passage.

[0011] Furthermore, the interstage combined channel is connected to the primary pump chamber through the exhaust port of the primary pump chamber, the interstage combined channel is connected to the secondary pump chamber through the intake port of the secondary pump chamber, the intake channel is connected to the primary pump chamber through the intake port of the primary pump chamber, and the exhaust channel is connected to the secondary pump chamber through the exhaust port of the secondary pump chamber.

[0012] Furthermore, the interstage connecting channel, the intake channel, and the exhaust channel are all gradually narrowing flow channels, and the cross-sectional area of ​​the interstage connecting channel, the intake channel, and the exhaust channel all gradually decrease along the gas flow direction.

[0013] Furthermore, the rotational speed of the second-stage impeller is lower than that of the first-stage impeller, preferably the rotational speed of the second-stage impeller is 50-80% of that of the first-stage impeller.

[0014] Furthermore, the second-stage impeller rotates in the same direction as the first-stage impeller.

[0015] Furthermore, an annular gas phase space is formed between the first-stage impeller and the casing, and the average thickness of the annular gas phase space is ≥10mm.

[0016] The beneficial effects of this invention are as follows:

[0017] The secondary impeller is nested outside the primary impeller, forming a radial layout of "internal primary impeller and external secondary impeller", which replaces the traditional axial series structure of the primary and secondary impellers, significantly shortening the axial dimension of the two-stage liquid ring pump. At the same time, the distribution plate integrates the primary pump chamber suction port, the primary pump chamber exhaust port, the secondary pump chamber suction port, and the secondary pump chamber exhaust port. The stiffeners on the end cover form an interstage joint channel, a suction channel, and an exhaust channel, eliminating the need for external connecting pipes. The overall structure is more compact, reducing the footprint and improving space utilization.

[0018] The exhaust port of the first-stage pump chamber and the intake port of the second-stage pump chamber are directly connected through an interstage joint channel, resulting in a short flow distance and fewer turns for the gas from the first-stage pump chamber to the second-stage pump chamber. At the same time, the interstage joint channel, the intake channel, and the exhaust channel are all gradually narrowing flow channels, which can reduce turbulence losses, reduce gas flow resistance, reduce energy loss, and improve the operating efficiency of the two-stage liquid ring pump. The first-stage pump chamber and the second-stage pump chamber are uniquely connected through the interstage joint channel, avoiding the shaft hole backflow problem caused by the "shaft penetrating both stages" in traditional two-stage liquid ring pumps, ensuring unidirectional gas flow from the first-stage pump chamber to the second-stage pump chamber, resulting in more stable compression.

[0019] The motor's output shaft drives the secondary impeller via a drive gear, a primary transmission gear, and a secondary transmission gear. By adjusting the transmission ratios of the drive gear, the primary transmission gear, and the secondary transmission gear, the compression ratios of the primary and secondary pump chambers can be flexibly allocated to meet the needs of different gas compression scenarios. The secondary impeller rotates in the same direction as the primary impeller, and the inner wall of the secondary impeller serves as the boundary of the primary pump chamber, reducing the viscous resistance between the liquid ring and the inner wall of the pump chamber, minimizing energy loss, and further improving the overall efficiency of the two-stage liquid ring pump.

[0020] The eccentricity of the first-stage impeller relative to the first-stage pump chamber is opposite to that of the second-stage impeller relative to the second-stage pump chamber. This reverse eccentricity design can counteract the inertial force and centrifugal force between the first-stage and second-stage impellers, improve the balance performance of the two-stage liquid ring pump, and reduce overall vibration. At the same time, the annular gas phase space can absorb and attenuate operating noise. Combined with the isolation effect of the casing, it can achieve a low-noise and highly stable operating effect. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention;

[0022] Figure 2 This is the front view of the present invention;

[0023] Figure 3 This is a side view of the present invention;

[0024] Figure 4 This is a top view of the present invention;

[0025] Figure 5 yes Figure 2 Sectional view at point AA;

[0026] Figure 6 yes Figure 3 Sectional view at point BB;

[0027] Figure 7 yes Figure 3 Sectional view at CC;

[0028] Figure 8 yes Figure 3 Sectional view at point DD;

[0029] In the picture:

[0030] 1. Casing; 2. First-stage impeller; 3. Second-stage impeller; 4. Motor; 5. First-stage pump chamber; 6. Second-stage pump chamber; 7. Drive gear; 8. First-stage transmission gear; 9. Second-stage transmission gear; 10. End cover; 11. Distribution plate; 12. First-stage pump chamber intake port; 13. First-stage pump chamber exhaust port; 14. Second-stage pump chamber intake port; 15. Second-stage pump chamber exhaust port; 16. Interstage connecting channel; 17. Intake channel; 18. Exhaust channel; 19. Intake port; 20. Exhaust port. Detailed Implementation

[0031] The present invention will now be described and illustrated in detail with reference to the embodiments.

[0032] Example 1

[0033] like Figure 1-8 As shown, the nested two-stage liquid ring pump includes a housing 1, within which a primary impeller 2 and a secondary impeller 3 are disposed. The secondary impeller 3 is nested outside the primary impeller 2, forming a primary pump chamber 5 between the secondary impeller 3 and the primary impeller 2, and a secondary pump chamber 6 between the housing 1 and the secondary impeller 3. The eccentricity direction of the primary impeller 2 relative to the primary pump chamber 5 is opposite to the eccentricity direction of the secondary impeller 3 relative to the secondary pump chamber 6. A motor 4 is disposed on one side of the housing 1, and the output shaft of the motor 4 is coaxially and fixedly connected to the primary impeller 2. A [missing information - likely a device or component] is also fixedly mounted on the output shaft of the motor 4. A drive gear 7 is provided, which is connected to the second-stage impeller 3 in sequence through a first-stage transmission gear 8 and a second-stage transmission gear 9. An end cover 10 is provided at the end of the housing 1 away from the motor 4. A distribution plate 11 is provided between the end cover 10 and the housing 1. The distribution plate 11 is provided with a first-stage pump chamber suction hole 12, a first-stage pump chamber exhaust hole 13, a second-stage pump chamber suction hole 14, and a second-stage pump chamber exhaust hole 15. Several stiffening plates are provided inside the end cover 10. The stiffening plates and the inner wall of the end cover 10 form an interstage connecting channel 16, a suction channel 17, and an exhaust channel 18.

[0034] The secondary impeller 3 is nested outside the primary impeller 2 to form a radial layout, replacing the traditional axial series structure. This significantly shortens the axial dimension of the two-stage liquid ring pump, making the overall structure more compact and reducing the footprint. The eccentricity of the primary impeller 2 relative to the primary pump chamber 5 is opposite to that of the secondary impeller 3 relative to the secondary pump chamber 6, which can offset some of the inertial and centrifugal forces and reduce the vibration of the two-stage liquid ring pump. The drive gear 7 drives the secondary impeller 3 to rotate at different speeds through the primary transmission gear 8 and the secondary transmission gear 9 in sequence, which can flexibly adjust the interstage compression ratio and widen the working range. The distribution plate 11 integrates the primary pump chamber suction port 12, the primary pump chamber exhaust port 13, the secondary pump chamber suction port 14, and the secondary pump chamber exhaust port 15. The end cover 10 ribs form the interstage joint channel 16, the suction channel 17, and the exhaust channel 18, which can eliminate the need for external pipelines, shorten the interstage flow path, reduce flow resistance and energy loss, and at the same time avoid shaft hole backflow caused by shaft penetration, ensuring stable compression efficiency.

[0035] The secondary transmission gear 9 meshes with the internal gear ring fixed inside the secondary impeller 3.

[0036] The distribution plate 11 is arranged in a circular shape.

[0037] The end cap 10 is provided with an air intake 19 and an exhaust port 20. The air intake 19 is connected to the air intake channel 17, and the exhaust port 20 is connected to the exhaust channel 18.

[0038] The intake passage 17 is adjacent to the interstage combined passage 16 and the exhaust passage 18, respectively, and the interstage combined passage 16 is adjacent to the exhaust passage 18.

[0039] Interstage connecting channel 16 connects to primary pump chamber 5 via primary pump chamber exhaust port 13, and connects to secondary pump chamber 6 via secondary pump chamber intake port 14. Intake channel 17 connects to primary pump chamber 5 via primary pump chamber intake port 12, and exhaust channel 18 connects to secondary pump chamber 6 via secondary pump chamber exhaust port 15. The interstage connecting channel 16, intake channel 17, and exhaust channel 18 work together to create an internal gas flow path, replacing external piping and reducing flow resistance and leakage risks. Simultaneously, they ensure unidirectional, orderly gas flow, avoiding turbulence and backflow, and improving the compression efficiency of the two-stage liquid ring pump.

[0040] The interstage connecting channel 16, the intake channel 17, and the exhaust channel 18 are all gradually narrowing flow channels. The cross-sectional areas of the interstage connecting channel 16, the intake channel 17, and the exhaust channel 18 all gradually decrease along the gas flow direction. The interstage connecting channel 16, the intake channel 17, and the exhaust channel 18 can reduce airflow impact and turbulence losses, reduce flow resistance, further reduce energy loss, and improve the operating efficiency of the two-stage liquid ring pump.

[0041] The rotational speed of the second-stage impeller 3 is less than that of the first-stage impeller 2, and the rotational speed of the second-stage impeller 3 is 75% of that of the first-stage impeller 2.

[0042] The rotation direction of the secondary impeller 3 is the same as that of the primary impeller 2. This reduces the viscous resistance between the liquid ring in the primary pump chamber 5 and the inner wall of the secondary impeller 3, reduces liquid ring energy loss, and further improves the overall efficiency of the two-stage liquid ring pump.

[0043] The eccentricity of the rotation center of the first-stage impeller 2 relative to the rotation center of the second-stage impeller 3 is equal to the eccentricity of the rotation center of the second-stage impeller 3 relative to the center of the casing 1.

[0044] An annular gas phase space is formed between the first-stage impeller 2 and the casing 1, with an average thickness of ≥10mm. The annular gas phase space enhances the absorption of noise, and together with the blocking effect of the casing 1, it significantly reduces the overall operating noise of the two-stage liquid ring pump, thus reducing noise pollution.

[0045] like Figure 8 As shown, two straight lines are drawn with the center of the distribution plate 11 as the reference point. One line connects the top of the suction port 14 of the secondary pump chamber to the reference point, and the other line is the common tangent of the top end of the exhaust port 13 of the primary pump chamber relative to the reference point. The angle between the two lines is θ, where θ ≤ 30°. The angle θ minimizes the flow path of gas from the exhaust port 13 of the primary pump chamber to the suction port 14 of the secondary pump chamber, avoiding kinetic energy loss caused by a long path. This allows the gas pressure after primary compression to be used more effectively for secondary compression, improving the interstage energy transfer efficiency and thus increasing the pump's operating efficiency.

[0046] Working principle and process:

[0047] I. Device Start-up:

[0048] After the motor 4 starts, the output shaft of the motor 4 drives the first-stage impeller 2 to rotate synchronously; at the same time, the drive gear 7 on the output shaft of the motor 4 drives the first-stage transmission gear 8 and the second-stage transmission gear 9 in sequence, and finally drives the second-stage impeller 3 to rotate in the same direction as the first-stage impeller 2.

[0049] Under the action of centrifugal force, the working fluid in the primary pump chamber 5 and the secondary pump chamber 6 is thrown towards the chamber wall. The working fluid forms a primary liquid ring in the primary pump chamber 5 between the primary impeller 2 and the secondary impeller 3, and forms a secondary liquid ring in the secondary pump chamber 6 between the housing 1 and the secondary impeller 3.

[0050] II. Level 1 Compression:

[0051] Gas enters the end cap 10 through the intake port 19, and then enters the gas phase space of the primary pump chamber 5 through the intake hole 12 of the primary pump chamber of the distribution plate 11.

[0052] Because the first-stage impeller 2 is eccentric relative to the first-stage pump chamber 5, as the first-stage impeller 2 rotates, the volume between the gas and the first-stage liquid ring periodically increases and decreases. When the volume increases, the gas is drawn in, and when the volume decreases, the gas is initially compressed.

[0053] The gas after initial compression is discharged through the exhaust port 13 of the first-stage pump chamber of the distribution plate 11, and enters the second-stage compression stage through the interstage combined channel 16 formed by the rib plate of the end cover 10.

[0054] Level 3 and Level 2 Compression:

[0055] The gas compressed in the first stage enters the gas phase space of the second stage pump chamber 6 through the suction port 14 of the second stage pump chamber of the distribution plate 11.

[0056] The secondary impeller 3 is eccentrically opposite to the secondary pump chamber 6. As the secondary impeller 3 rotates, the volume between the gas and the secondary liquid ring increases and decreases periodically. When the volume increases, the gas is drawn in, and when the volume decreases, the gas is initially compressed.

[0057] The gas after secondary compression is discharged through the exhaust port 15 of the secondary pump chamber of the distribution plate 11, passes through the exhaust channel 18 of the end cover 10, and finally exits the device from the exhaust port 20 of the end cover 10.

Claims

1. A nested two-stage liquid ring pump, comprising a housing (1), wherein a first-stage impeller (2) and a second-stage impeller (3) are disposed within the housing (1), characterized in that, The secondary impeller (3) is nested outside the primary impeller (2), and a primary pump chamber (5) is formed between the secondary impeller (3) and the primary impeller (2). A secondary pump chamber (6) is formed between the housing (1) and the secondary impeller (3). The eccentricity of the primary impeller (2) relative to the primary pump chamber (5) is opposite to the eccentricity of the secondary impeller (3) relative to the secondary pump chamber (6). A motor (4) is provided on one side of the housing (1). The output shaft of the motor (4) is coaxially and fixedly connected to the primary impeller (2). A drive gear (7) is also fixedly provided on the output shaft of the motor (4). The drive gear (7) passes through the primary transmission in sequence. Gear (8), secondary transmission gear (9) and secondary impeller (3) are connected in transmission. An end cover (10) is provided at the end of the housing (1) away from the motor (4). A distribution plate (11) is provided between the end cover (10) and the housing (1). The distribution plate (11) is provided with a primary pump chamber suction hole (12), a primary pump chamber exhaust hole (13), a secondary pump chamber suction hole (14) and a secondary pump chamber exhaust hole (15). Several stiffening plates are provided inside the end cover (10). The several stiffening plates and the inner wall of the end cover (10) enclose an interstage joint channel (16), a suction channel (17) and an exhaust channel (18). An air intake port (19) and an exhaust port (20) are provided on the end cap (10). The air intake port (19) is connected to the air intake channel (17), and the exhaust port (20) is connected to the exhaust channel (18). The interstage combined channel (16) is connected to the first-stage pump chamber (5) through the exhaust port (13) of the first-stage pump chamber. The interstage combined channel (16) is connected to the second-stage pump chamber (6) through the intake port (14) of the second-stage pump chamber. The intake channel (17) is connected to the first-stage pump chamber (5) through the intake port (12) of the first-stage pump chamber. The exhaust channel (18) is connected to the second-stage pump chamber (6) through the exhaust port (15) of the second-stage pump chamber.

2. The nested two-stage liquid ring pump according to claim 1, characterized in that, The secondary transmission gear (9) meshes with the internal gear ring fixed inside the secondary impeller (3).

3. The nested two-stage liquid ring pump according to claim 1, characterized in that, The distribution plate (11) is set in a circular shape.

4. The nested two-stage liquid ring pump according to claim 1, characterized in that, The intake passage (17) is adjacent to the interstage combined passage (16) and the exhaust passage (18) respectively, and the interstage combined passage (16) is adjacent to the exhaust passage (18).

5. The nested two-stage liquid ring pump according to claim 1, characterized in that, The interstage connecting channel (16), the intake channel (17) and the exhaust channel (18) are all gradually narrowing flow channels. The cross-sectional area of ​​the interstage connecting channel (16), the intake channel (17) and the exhaust channel (18) all gradually decrease along the gas flow direction.

6. The nested two-stage liquid ring pump according to claim 1, characterized in that, The rotational speed of the second-stage impeller (3) is less than that of the first-stage impeller (2).

7. The nested two-stage liquid ring pump according to claim 1, characterized in that, The rotation direction of the second-stage impeller (3) is the same as that of the first-stage impeller (2).

8. The nested two-stage liquid ring pump according to claim 1, characterized in that, An annular gas phase space is formed between the first-stage impeller (2) and the shell (1), and the average thickness of the annular gas phase space is ≥10mm.

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