A liquid ring vacuum pump using liquid phase micro jet to suppress gas phase leakage flow

Abstract

The invention discloses a liquid ring vacuum pump which utilizes liquid phase micro jets to suppress gas phase leakage flow. The liquid ring vacuum pump comprises a housing, an impeller eccentrically installed in the housing, and a cover plate and a distribution plate located at both ends of the impeller. A jet inlet and a jet outlet are provided on the cover plate and the distribution plate. The jet inlet is located in a liquid phase high pressure zone at the edge of the suction side, and the jet outlet is located in a compression zone in a gas ring on the exhaust side. A jet channel for connecting the jet inlet and the jet outlet is provided in the cover plate. By opening a self-sustaining jet channel in the cover plate, a small flow rate and high pressure liquid in the liquid phase high pressure zone is sprayed into the compression zone, thereby suppressing gap leakage flow, reducing hydraulic loss in the pump caused by gap leakage flow, reducing complex hydraulic excitation induced by unsteady gap leakage flow, improving efficiency, operation stability and service life of the pump, and having a simple structure, only needs to be modified and processed on the prototype cover plate of the liquid ring pump without changing the original main body configuration.

Description

Technical Field

[0001] The invention relates to a liquid ring vacuum pump, in particular to a liquid ring vacuum pump which utilizes liquid phase micro jet to suppress gas phase leakage flow. Background Art

[0002] Liquid ring vacuum pump is a fluid machine that uses liquid as the intermediate medium for energy conversion and is used to pump gas.

[0003] Due to its advantages of large pumping flow, no rotor metal surface contact and nearly isothermal compression, it has great advantages in pumping flammable, explosive, toxic and condensable gases, and is widely used in coal mining, petrochemical and nuclear power fields. Due to the complex gas-liquid two-phase flow in the liquid ring vacuum pump, it has problems such as low efficiency, high vibration and noise, and short service life. The impeller of the liquid ring vacuum pump is eccentrically installed in the casing. Under the rotation of the impeller, the gas-liquid two-phase flow in the pump is separated to form a liquid ring of equal thickness, which forms small cavities of unequal volumes between the flow channel between the blades and the side cover; under the rotation of the impeller, the volume of the cavity changes periodically, and the area where the cavity volume gradually increases is in a vacuum state, which is connected to the suction port, and the pump achieves suction; the pressure in the area where the cavity volume gradually decreases increases, and it is connected to the exhaust port, and the pump achieves exhaust. Therefore, there is a pressure difference between the exhaust side and the suction side in the gas phase area of ​​the liquid ring vacuum pump. In order to ensure the relative movement between the rotor and the stator in the liquid ring vacuum pump, the axial end face of the impeller leaves 0.2~0.5mm between the distribution plate and the cover plate When the pump is working, under the pressure difference between the discharge and suction sides, a leakage flow will be formed from the working surface to the back of the blade through the axial end face gap of the blade. The gap leakage flow reduces the sealing performance of the gap, resulting in a decrease in the suction vacuum and flow rate of the pump. In addition, the leakage flow interacts with the mainstream in the impeller to produce a complex flow structure, resulting in increased hydraulic losses in the pump and complex changes in hydraulic excitation characteristics, affecting the efficient and stable operation and service life of the pump. The leakage flow of the axial end face gap of the liquid ring vacuum pump impeller is most serious in the compression area of ​​the pump. Summary of the invention

[0004] The technical task of the present invention is to provide a liquid ring vacuum pump which utilizes liquid phase micro jets to suppress gas phase leakage flow in view of the above deficiencies in the prior art.

[0005] The technical solution adopted by the present invention to solve its technical problems is: a liquid ring vacuum pump that uses liquid phase microjets to suppress gas phase leakage flow, including a housing, an impeller eccentrically installed in the housing, and a cover plate located at the end of the impeller, a jet inlet and a jet outlet are provided on the cover plate, the jet inlet and the jet outlet are both located in the lower half of the cover plate, the horizontal position of the jet outlet is higher than the jet inlet, the jet inlet is located in the liquid phase high pressure area at the edge of the suction side, the jet outlet is located in the compression area in the gas ring on the exhaust side, and a jet channel for connecting the jet inlet and the jet outlet is provided in the cover plate.

[0006] Further improvement: the jet inlet is arranged perpendicularly to the jet channel, and the jet outlet is arranged inclined to the jet channel, and the inclination angle is β1, wherein the inclination angle β1≤20° will increase the momentum of the microjet along the direction parallel to the inner wall of the cover plate when flowing out of the jet outlet, thereby achieving a better suppression effect on the gap leakage flow.

[0007] Further improvement: the inclination angle of the jet channel is β2, wherein β2≤30°, and the radius angle between the jet outlet and the shell in the vertical direction is β3, wherein 10°≤β3≤25°.

[0008] Further improvement: A jet inlet, a jet outlet and a jet channel are provided on the distribution plate at the front end of the impeller, and the jet inlet, jet outlet and jet channel on the distribution plate and the cover plate are mirror-symmetrical, so that corresponding suppression effects can be achieved at both ends of the impeller axis.

[0009] Advantages of the present invention: In view of the bottleneck problems of low efficiency and poor operation stability of the current liquid ring vacuum pump, the present invention opens several groups of tubular jet channels in the side cover of the liquid ring vacuum pump to connect the high-pressure area near the inner wall of the pump casing with the low-pressure area at the gas phase leakage position; under the action of the pressure difference, a small flow of working liquid flows out of the tubular channel to form a micro-jet, which controls the gas phase leakage flow flowing out of the axial tip gap of the impeller, reduces the hydraulic loss in the pump caused by the gap leakage flow, reduces the complex hydraulic excitation induced by the unsteady gap leakage flow, and improves the efficiency, operation stability and service life of the pump. The leakage flow control structure of the present invention is easy to design and process, and has a simple structure. It only needs to be modified on the prototype cover plate of the liquid ring pump without changing the original main body configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a structural schematic diagram of the present invention.

[0011] Figure 2 The present invention Figure 1 A partial enlarged view of point C in the middle.

[0012] Figure 3 It is a schematic diagram of the position structure of the jet channel of the present invention.

[0013] Figure 4 It is a structural schematic diagram of gas leakage of the present invention.

[0014] Figure 5 It is a pressure distribution diagram inside the existing liquid ring vacuum pump of the present invention.

[0015] Figure 6 The invention discloses a leakage flow structure of the axial blade tip clearance of an impeller of a liquid ring vacuum pump.

[0016] Figure 7 It is the pressure pulsation characteristic of the working liquid near the inner wall of the shell of the existing liquid ring vacuum pump of the present invention.

[0017] In the figure: impeller 1, casing 2, cover plate 3, jet inlet 5, jet channel 6, jet outlet 7, distribution plate 8, air inlet A, suction side A1, liquid phase high pressure area A2, air outlet B, exhaust side B1, compression area B2, gas-liquid interface B3. DETAILED DESCRIPTION

[0018] The present invention is described in detail below with reference to the accompanying drawings.

[0019] As shown in the figure, a liquid ring vacuum pump that uses liquid phase microjets to suppress gas phase leakage flow includes a housing 2, an impeller 1 eccentrically installed in the housing 2, and a cover plate 3 located at the end of the impeller 1, a jet inlet 5 and a jet outlet 7 are provided on the cover plate, the jet inlet 5 and the jet outlet 7 are both located in the lower half of the cover plate 3, the horizontal position of the jet outlet 7 is higher than the jet inlet 5, the gas-liquid two-phase flow in the pump is separated under the rotation of the impeller 1, and a gas-liquid interface B3 is formed at the separation point, the inner side of the gas-liquid interface B3 is gas, and the outer side is liquid, the jet inlet 5 is located in the liquid phase high pressure area A2 at the edge of the suction side A1, the jet outlet 7 is located in the compression area B2 in the gas ring of the exhaust side B1, and a jet channel 6 for connecting the jet inlet 5 and the jet outlet 7 is provided in the cover plate 3.

[0020] The jet inlet 5 is arranged perpendicularly to the jet channel 6, and the jet outlet 7 is arranged obliquely to the jet channel 6, and the inclination angle is β1, wherein the inclination angle β1≤20° will increase the momentum of the microjet along the direction parallel to the inner wall of the cover plate 3 when flowing out of the jet outlet 7, thereby achieving a better suppression effect on the gap leakage flow.

[0021] The inclination angle of the jet channel 6 is β2, where β2≤30°, and the radial angle between the jet outlet 7 and the shell 2 in the vertical direction is β3, where 10°≤β3≤25°. The gap leakage is most significant within the angle range of β3, so setting the jet outlet 7 in this area has the best suppression effect on the leakage gas.

[0022] A jet inlet 5, a jet outlet 7 and a jet channel 6 are provided on the distribution plate 8 at the front end of the impeller 1. The jet inlet 5, the jet outlet 7 and the jet channel 6 on the distribution plate 8 are mirror-symmetrical with the jet inlet 5, the jet outlet 7 and the jet channel 6 on the cover plate 3, so that a corresponding suppression effect can be achieved at both ends of the impeller axial direction.

[0023] The working principle is as follows: the present invention opens a self-sustaining jet channel 6 in the distribution plate 8 at the front end of the impeller 1 and the cover plate 3 at the end. At the suction side A1, a small flow of high-pressure working liquid located in the liquid phase high-pressure area A2 enters the jet channel 6 through the jet inlet 5, and then is ejected from the jet outlet 7 to the compression area B2 of the exhaust side B1. The high-speed micro jet ejected from the jet outlet 7 suppresses the gap leakage flow.

[0024] At the same time, due to the pressure difference between the liquid phase high-pressure area A2 and the gas phase leakage flow low-pressure area A3, the continuity of the microjet during the operation of the pump can be guaranteed, and the pressure pulsation characteristics of the working liquid near the inner wall of the shell 2 can cause the microjet to have a certain pulse characteristic, which can enhance its suppression effect on the leakage flow. Therefore, the present invention does not need to add additional auxiliary equipment, has a simple structure, is easy to process, and can achieve effective control of the leakage flow of the axial blade tip clearance of the liquid ring pump impeller.

[0025] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A liquid ring vacuum pump that utilizes liquid phase micro jets to suppress gas phase leakage flow, comprising a housing, an impeller eccentrically mounted in the housing, and a cover plate located at the end of the impeller, characterized in that: A jet inlet and a jet outlet are provided on the cover plate, and the jet inlet and the jet outlet are both located in the lower half of the cover plate, the horizontal position of the jet outlet is higher than the jet inlet, the jet inlet is located in the liquid phase high pressure area at the edge of the suction side, and the jet outlet is located in the compression area in the gas ring on the exhaust side, and a jet channel for connecting the jet inlet and the jet outlet is provided in the cover plate; the jet inlet is vertically arranged with the jet channel, and the jet outlet is inclined with the jet channel, and the inclination angle is β1, wherein β1≤20°; the inclination angle of the jet channel is β2, wherein β2≤30°, and the angle between the jet outlet and the radius in the vertical direction of the shell is β3, wherein 10°≤β3≤25°.

2. A liquid ring vacuum pump utilizing liquid phase micro jets to suppress gas phase leakage flow according to claim 1, characterized in that: A jet inlet, a jet outlet and a jet channel are arranged on the distribution plate at the front end of the impeller, and the jet inlet, the jet outlet and the jet channel on the distribution plate and the cover plate are mirror-symmetrical.

Images