Liquid ring pump control
By introducing a gas pipeline and controlling the valve during the initial startup of the liquid ring pump, the cavitation problem during startup was solved, resulting in reduced noise and wear, and improved reliability and efficiency of the liquid ring pump.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- EDWARDS TECH VACUUM ENG (QINGDAO) CO LTD
- Filing Date
- 2018-10-25
- Publication Date
- 2026-07-10
AI Technical Summary
Cavitation during startup of liquid ring pumps causes wear and noise, especially when operating under low pressure/high vacuum conditions. Existing check valves open slowly, making it difficult to solve the startup cavitation problem.
By introducing a gas pipeline and controller valve at the inlet of the liquid ring pump, the valve is opened during the initial startup of the liquid ring pump and closed after the check valve is opened, thus reducing cavitation during startup.
It effectively reduces or eliminates cavitation during the start-up of liquid ring pumps, lowers noise and reduces wear, and improves the reliability and efficiency of liquid ring pumps.
Smart Images
Figure CN122359331A_ABST
Abstract
Description
Technical Field
[0001] This invention is a divisional application of Chinese Patent Application No. 201880091210.2. The invention relates to the control of liquid ring pumps. Background Technology
[0002] A liquid ring pump is a known type of pump commonly used commercially as a vacuum pump and as a gas compressor. A liquid ring pump typically includes a housing having a chamber therein, a shaft extending into the chamber, an impeller mounted to the shaft, and a drive system such as a motor, operatively connected to the shaft to drive it. The impeller and shaft are eccentrically positioned within the chamber of the liquid ring pump.
[0003] During operation, the chamber is partially filled with an operating fluid (also known as the working fluid). As the drive system drives the shaft and impeller, a liquid ring forms on the inner wall of the chamber, thereby providing a seal that isolates the individual volumes between adjacent impeller blades. The impeller and shaft are eccentrically positioned with respect to the liquid ring, which results in a periodic change in the volume enclosed between the adjacent blades of the impeller and the liquid ring.
[0004] In the portion of the chamber where the liquid ring is further away from the shaft, there is a larger volume between the adjacent impeller blades, resulting in lower pressure within it. This allows the portion of the liquid ring further away from the shaft to act as the intake zone. In the portion of the chamber where the liquid ring is closer to the shaft, there is a smaller volume between the adjacent impeller blades, resulting in higher pressure within it. This allows the portion of the liquid ring closer to the shaft to act as the exhaust zone.
[0005] Examples of liquid ring pumps include single-stage liquid ring pumps and multi-stage liquid ring pumps. A single-stage liquid ring pump involves the use of only a single chamber and impeller. A multi-stage liquid ring pump (e.g., two-stage) involves the use of multiple chambers and impellers connected in series. Summary of the Invention
[0006] Liquid ring pumps can be used with a check valve located at or near the inlet of the liquid ring pump. The check valve can be configured to allow gas to be pumped into the liquid ring pump and to prevent or block the flow of gas in the opposite direction (i.e., outflow from the liquid ring pump inlet).
[0007] The inventors have recognized that during startup (i.e., when the liquid ring pump begins pumping gas after a period of inactivity), the check valve can only open relatively slowly (e.g., within a few seconds). The inventors have further recognized that this can lead to cavitation within the liquid ring pump during startup. In some liquid ring pumps, especially those operating under low-pressure / high-vacuum conditions, cavitation is often a significant cause of wear and failure. Moreover, startup cavitation can result in disturbing noise. Therefore, it is often desirable to prevent or inhibit startup cavitation in liquid ring vacuum pumps.
[0008] The inventors have further realized that by introducing an airflow into the inlet manifold (after the check valve) of the liquid ring pump during startup, startup cavitation can be reduced or eliminated.
[0009] In a first aspect, the present invention provides a system comprising: a suction line; a liquid ring pump coupled to the suction line, the liquid ring pump including a chamber and an impeller mounted in the chamber; a check valve arranged to allow fluid to flow into the chamber via the suction line and to prevent or block fluid from flowing out of the chamber to the suction line; a gas line coupled to the liquid ring pump such that gas can flow into the liquid ring pump via the gas line, the gas line being coupled to the liquid ring pump between the check valve and the chamber; a valve disposed on the gas line; and a controller configured to control the valve.
[0010] The controller can be configured to open the valve within a first predetermined time period starting from the activation of the liquid ring pump.
[0011] The liquid ring pump may also include a shaft on which an impeller is mounted. The system may also include a motor configured to drive the shaft. A controller may be configured to activate the liquid ring pump by controlling the motor to rotate the shaft.
[0012] The controller can be configured to open the valve for at least a certain period of time when the check valve is closed. The controller can be configured to close the valve for a second predetermined period of time after opening the valve. The controller can be configured to close the valve in response to determining that the check valve is open.
[0013] The check valve can be installed on the suction line. The gas line can be connected to the suction line between the check valve and the inlet of the liquid ring pump.
[0014] The liquid ring pump may include an inlet manifold. A check valve may be integrated into the inlet manifold. A gas line may be connected to the inlet manifold between the chamber and the integrated check valve in its closed position. The integrated check valve may include an annular flange defining an opening, and an object movable between a first position and a second position, wherein in the first position the object is positioned away from the opening to avoid obstructing the opening, and in the second position the object is abutted against the annular flange to obstruct the opening. The gas line may be connected to the inlet manifold between the annular flange and the chamber.
[0015] The system may also include silencers installed on the gas pipeline.
[0016] In another aspect, the present invention provides a liquid ring pump comprising an inlet manifold and a chamber fluidly connected to the inlet manifold. The inlet manifold includes an integral check valve and a gas inlet between the integral check valve and the chamber in its closed position.
[0017] An integrated check valve may include an annular flange defining an opening, and an object movable between a first position and a second position, wherein in the first position the object is positioned away from the opening to avoid obstructing it, and in the second position the object is abutted against the annular flange to obstruct the opening. A gas inlet may be located between the annular flange and a chamber.
[0018] In another aspect, the present invention provides a control method for a control system. This system conforms to any of the foregoing aspects. The method includes activating a liquid ring pump; and, after activating the liquid ring pump and while the check valve is closed, opening a valve to allow gas to flow into the liquid ring pump via a gas line.
[0019] The method may also include, thereafter, closing the valve and opening the check valve.
[0020] The gas can be air or an inert gas. The valve can be a solenoid valve.
[0021] In any of the foregoing aspects, the system may further include a pump configured to pump operating fluid to a liquid ring pump via an operating fluid line. The controller may be a controller selected from a set of controllers including: proportional controllers, integral controllers, derivative controllers, proportional-integral controllers, proportional-integral-derivative controllers, proportional-derivative controllers, and fuzzy logic controllers. The system may further include an operating fluid recirculation system configured to recirculate the operating fluid from the discharge fluid of the liquid ring pump back into the liquid ring pump. The operating fluid recirculation system may include a separator configured to separate the operating fluid from the discharge fluid of the liquid ring pump. The operating fluid recirculation system may include a cooling device configured to cool the recirculated operating fluid before it is received by the liquid ring pump. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of a vacuum system (not to scale). Figure 2 This is a schematic diagram of a liquid ring pump (not to scale); and Figure 3 It is a process flow diagram showing certain steps of a process that can be performed by a vacuum system; and Figures 4 to 6 This illustrates a liquid ring pump with an integrated check valve. Figure 3 Schematic diagrams of the corresponding different stages of the process (not to scale). Detailed Implementation
[0023] Figure 1This is a schematic diagram (not to scale) showing vacuum system 2. Vacuum system 2 is connected to facility 4 such that, in operation, vacuum system 2 establishes a vacuum or low-pressure environment at facility 4 by extracting gas (e.g., air) from facility 4.
[0024] In this embodiment, the vacuum system 2 includes a check valve 6, a first valve 8, a silencer 9, a liquid ring pump 10, a motor 12, a separator 14, a pump system 16, a heat exchanger 18, and a controller 20.
[0025] Facility 4 is connected to the gas inlet of liquid ring pump 10 via suction or vacuum line or pipe 34.
[0026] In this embodiment, check valve 6 is installed on suction line 34. Check valve 6 is located between facility 4 and liquid ring pump 10.
[0027] The check valve 6 is configured to allow fluid (e.g., gas such as air) to flow from facility 4 to liquid ring pump 10 and to prevent or block fluid flow in the opposite direction (i.e., from liquid ring pump 10 to facility 4).
[0028] The gas inlet of the liquid ring pump 10 is also connected to an air (or gas) conduit 36 (which may also be referred to as an air (or gas) line), through which air can be fed into the gas inlet of the liquid ring pump 10. In this embodiment, the air conduit 36 connects to the suction line 34 between the check valve 6 and the gas inlet of the liquid ring pump 10.
[0029] In this embodiment, the check valve 6 does not prevent or block airflow through the air conduit 36 to the liquid ring pump 10. The air conduit 36 can be considered to bypass the check valve 6.
[0030] The first valve 8 is installed on the air duct 36. The silencer 9 is installed on the air duct 36. The first valve 8 is installed between the suction line 34 and the silencer 9. The silencer 9 is installed between the first valve 8 and the inlet of the suction line 34.
[0031] The first valve 8 can be a solenoid valve.
[0032] The silencer 9 can also be referred to as a muffler. The silencer 9 is an acoustic device that is configured to reduce the loudness of the sound pressure formed in the air duct 36 by the air drawn in by the liquid ring pump 10 through the air duct 36.
[0033] In this embodiment, the liquid ring pump 10 is a single-stage liquid ring pump.
[0034] The gas inlet of the liquid ring pump 10 is connected to the suction line 34. The gas outlet of the liquid ring pump 10 is connected to the discharge line or pipe 38. The liquid ring pump 10 is connected to the heat exchanger 18 via the first operating liquid line 40. The liquid ring pump 10 is configured to receive operating liquid from the heat exchanger 18 via the first operating liquid line 40. The liquid ring pump 10 is driven by the motor 12. Therefore, the motor 12 is the driver of the liquid ring pump 10.
[0035] Figure 2 This is a schematic diagram (not to scale) of a cross-section of an example liquid ring pump 10. More details will follow later in the description. Figure 2 The remaining parts of the vacuum system 2 will be described in more detail after the liquid ring pump 10 shown.
[0036] In this embodiment, the liquid ring pump 10 includes a housing 100 defining a generally cylindrical chamber 102, a shaft 104 extending into the chamber 102, and an impeller 106 fixedly mounted to the shaft 104. A gas inlet 108 of the liquid ring pump 10 (which is coupled to a suction line 34) is fluidly connected to an air inlet of the chamber 102. A gas outlet of the liquid ring pump 10 (… Figure 2 (Not shown in the image) is fluidly connected to the air outlet of chamber 102.
[0037] During operation of the liquid ring pump 10, the operating fluid is received in the chamber 102 via a first operating fluid conduit 40. In some embodiments, the operating fluid may additionally be received via a spray nozzle through a suction line 34. Furthermore, the shaft 104 is rotated by the motor 12, thereby rotating the impeller 106 within the chamber 102. As the impeller 106 rotates, the operating fluid (not shown in the figures) in the chamber 102 is forced against the wall of the chamber 102, thereby forming a liquid ring that seals and isolates the individual volumes between adjacent impeller blades. Moreover, gas (such as air) is drawn into the chamber 102 from the suction line 34 via the inlet and gas inlet 108 of the chamber 102. This gas flows into the volume formed between adjacent blades of the impeller 106. The rotation of the impeller 106 compresses the gas contained in this volume as it moves from the inlet of the chamber 102 to the outlet of the chamber 102 (where compressed gas exits the chamber 102). The compressed gas leaving chamber 102 then exits the liquid ring pump via gas outlet and discharge line 38.
[0038] Return now Figure 1 As described, discharge line 38 is connected between the gas outlet of liquid ring pump 10 and the inlet of separator 14. Separator 14 is connected to liquid ring pump 10 via discharge line 38 such that discharge fluid (i.e., compressed gas, which may include water droplets and / or vapor) is received by separator 14.
[0039] Separator 14 is configured to separate the discharge fluid received from liquid ring pump 10 into gas (e.g., air) and operating liquid. Thus, separator 14 provides recirculation of the operating liquid.
[0040] The gas separated from the received discharge fluid is discharged from the separator 14 and the vacuum system 2 via the system outlet pipe 42.
[0041] In this embodiment, separator 14 includes another inlet 44 through which separator 14 can receive an additional or "additional" supply of operating fluid from an operating fluid source (not shown in the figures). A second valve 46 is disposed along the other inlet 44. The second valve 46 is configured to control the flow of additional operating fluid into separator 14 via the other inlet 44. The second valve 46 may be a solenoid valve.
[0042] The separator 14 includes three operating liquid outlets. A first operating liquid outlet of the separator 14 is connected to a pump system 16 via a second operating liquid conduit 48, allowing operating liquid to flow from the separator 14 to the pump system 16. A second operating liquid outlet of the separator 14 is connected to an overflow conduit 50, which provides an outlet for excess operating liquid. A third operating liquid outlet of the separator 14 is connected to a drain or evacuation pipe 52, providing a line through which the separator can be drained of operating liquid. A third valve 54 is disposed along the drain pipe 52. The third valve 54 is configured to be either open or closed, thereby allowing or preventing operating liquid from flowing out of the separator 14 via the drain pipe 52, respectively. The third valve 54 may be a solenoid valve.
[0043] The separator 14 also includes a level indicator 56 configured to provide, for example, an indication of the amount of operating liquid in the separator 14 to a human user of the vacuum system 2. The level indicator 56 may include, for example, a transparent window through which the user can observe the liquid level in the liquid storage tank of the separator 14.
[0044] In this embodiment, in addition to being connected to the separator 14 via a second operating liquid conduit 48, the pump system 16 is also connected to the heat exchanger 18 via a third operating liquid conduit 58. The pump system 16 includes a pump (e.g., a centrifugal pump) and a motor configured to drive the pump. The pump system 16 is configured to pump the operating liquid out of the separator 14 via the second operating liquid conduit 48 and to pump the operating liquid to the heat exchanger 18 via the third operating liquid conduit 58.
[0045] The heat exchanger 18 is configured to receive relatively hot operating liquid from the pump system 16, cool the relatively hot operating liquid to provide relatively cold operating liquid, and output the relatively cold operating liquid.
[0046] In this embodiment, heat exchanger 18 is configured to cool the relatively hot operating liquid by transferring heat from the relatively hot operating liquid flowing through heat exchanger 18 to a fluid coolant also flowing through heat exchanger 18. The operating liquid and coolant are separated within heat exchanger 18 by a solid wall (through which heat is transferred), thereby preventing mixing of the operating liquid and coolant. Heat exchanger 18 receives coolant from a coolant source (not shown in the figures) via coolant inlet 60. Heat exchanger 18 discharges coolant (to which heat has been transferred) via coolant outlet 62.
[0047] The heat exchanger 18 includes an operating liquid outlet from which cooled operating liquid flows (i.e., pumped by the pump system 16). The operating liquid outlet is connected to a first operating liquid conduit 40. Thus, the heat exchanger 18 is connected to the liquid ring pump 10 via the first operating liquid conduit 40, such that in operation, cooled operating liquid is pumped from the heat exchanger 18 to the liquid ring pump 10 by the pump system 16.
[0048] The controller 20 may include one or more processors. In this embodiment, the controller 20 includes two variable frequency drives (VFDs), namely a first VFD 201 and a second VFD 202. The first VFD 201 is configured to control the speed of the motor 12. The first VFD 201 may include an inverter for controlling the motor 12. The second VFD 202 is configured to control the speed of the motor of the pump system 16. The second VFD 202 may include an inverter for controlling the motor of the pump system 16.
[0049] Controller 20 is connected to motor 12 via a first VFD 201 and via a first connector 66, such that control signals for controlling motor 12 can be transmitted from controller 20 to motor 12. The first connector 66 can be any suitable type of connector, including but not limited to wires or fiber optics, or wireless connectors. Motor 12 is configured to operate according to the control signals it receives from controller 20. See below for further details. Figure 3 The control of motor 12 by controller 20 is described in more detail.
[0050] The controller 20 is connected to the pump system 16 via a second VFD 202 and a second connector 68, such that control signals for controlling the pump system 16 can be sent from the controller 20 to the motor of the pump system 16. The second connector 68 can be any suitable type of connector, including but not limited to wires or fiber optics, or wireless connectors. The pump system 16 is configured to operate according to the control signals it receives from the controller 20.
[0051] The controller 20 is also connected to the first valve 8 via a third connector 70, such that control signals for controlling the first valve 8 can be transmitted from the controller 20 to the first valve 8. The third connector 70 can be any suitable type of connector, including but not limited to wires or fiber optic cables, or wireless connectors. The first valve 8 is configured to operate according to the control signals it receives from the controller 20. See below for further details. Figure 3 The control of the first valve 8 by the controller 20 is described in more detail.
[0052] The controller 20 can also be connected to the second valve 46 and the third valve 54 via corresponding connectors (not shown in the figure), so that control signals for controlling the second valve 46 and the third valve 54 can be sent from the controller 20 to the second valve 46 and the third valve 54.
[0053] Therefore, an embodiment of vacuum system 2 is provided.
[0054] The device including controller 20 for implementing the above arrangement and performing the method steps described later can be provided by constructing or adapting any suitable device (e.g., one or more computers or other processing devices or processors) and / or by providing additional modules. The device may include a computer, a network of computers, or one or more processors to implement instructions and use data, including instructions and data in the form of one or more computer programs stored in or on a machine-readable storage medium such as computer memory, computer disk, ROM, PROM, etc., or any combination of these or other storage media.
[0055] Now refer to Figure 3 An embodiment describing a control process that can be executed by vacuum system 2 is provided. It should be noted that details may be omitted in... Figure 3 Some process steps are depicted in the flowchart and described below, or may be presented in conjunction with those described below and in Figure 3 The different sequences of these process steps shown in the diagram are executed in different orders. Furthermore, although all process steps have been depicted as discrete, temporally sequential steps for convenience and ease of understanding, in reality some process steps may be executed simultaneously or at least partially overlapping in time.
[0056] Figure 3 This is a process flow diagram illustrating some steps of an embodiment of the control process implemented by the vacuum system 2.
[0057] At step s2, the vacuum system 2 is in its initial state. In this embodiment, in the initial state of the vacuum system 2, the liquid ring pump 10 is "off" or inactive (i.e., the motor 12 does not drive the liquid ring pump 10), the check valve 6 is closed, and the first valve 8 is closed.
[0058] In this embodiment, in the initial state, the gas pressure inside chamber 102 of the liquid ring pump 10 is higher than the gas pressure inside suction line 34 and at facility 4. Gas from inside chamber 102 of the liquid ring pump 10 tends to flow back into suction line 34 due to the pressure difference. This gas flow tends to close check valve 6, and the pressure difference across check valve 6 tends to hold check valve 6 in its closed position. In its closed position, check valve 6 prevents gas inside chamber 102 from flowing from chamber 102 to facility 4 through suction line 34. Check valve 6, in its closed position, also prevents operating fluid inside chamber 102 from flowing from chamber 102 to facility 4 through suction line 34.
[0059] At step s4, controller 20 activates liquid ring pump 10, i.e., liquid ring pump 10 is "turned on". Liquid ring pump 10 can be activated to meet the needs of facility 4, such as the need to pump gas from facility 4.
[0060] In this embodiment, the controller 20 controls the motor 12 to drive the liquid ring pump 10 via the first VFD 201 and via the first connector 66. Therefore, the motor 12 rotates the shaft 104, thereby causing the impeller 106 to rotate within the chamber 102. The rotation of the impeller 106 tends to cause a decrease in gas pressure within the chamber 102. This decrease in gas pressure within the chamber 102 is often rapid; for example, without air flowing in via the air duct 36, the gas pressure within the chamber can drop to its operating state (e.g., vacuum pump state) within approximately 1.5 seconds.
[0061] Although the decrease in gas pressure within chamber 102 caused by the activation of the liquid ring pump 10 tends to cause check valve 6 to open, check valve 6 may remain closed for some time (e.g., up to ten seconds, or up to five seconds), or open at a low speed after the liquid ring pump 10 is activated. This may be caused by, for example, a remaining pressure differential across check valve 6 or by the sticking of check valve 6.
[0062] In step s6, the controller 20 controls the first valve 8 to open via the third connector 70.
[0063] Preferably, the first valve 8 opens simultaneously with the activation of the liquid ring pump 10. In other words, preferably, steps s4 and s6 are performed approximately simultaneously. However, the first valve 8 may open either before or after the activation of the liquid ring pump 10, for example, during a predetermined period of time when the liquid ring pump 10 is started.
[0064] At step s8, the liquid ring pump 10 draws air into chamber 102 via its gas inlet 108. Air is drawn into the liquid ring pump 10 via the open first valve 8 and silencer 9 through air conduit 36. Due to the reduced gas pressure within chamber 102 caused by the activation of the liquid ring pump 10, air tends to be drawn into the liquid ring pump 10 through air conduit 36. Silencer 9 tends to reduce the noise associated with the liquid ring pump 10 drawing air in via air conduit 36.
[0065] A rapid pressure drop within the chamber 102 of the liquid ring pump 10 (e.g., during startup / activation of the liquid ring pump 10) can cause cavitation within the liquid ring pump 10 and / or generate noise. Introducing air into the liquid ring pump 10 at step s8 advantageously tends to slow the pressure drop within the chamber 102 when the liquid ring pump 10 is activated. For example, in some embodiments, introducing air into the liquid ring pump 10 at step s8 can increase the time taken for the gas pressure within the chamber to decrease to its operating state (e.g., vacuum pumping state) by about 1 second (e.g., from about 1.5 seconds to about 2.5 seconds). Therefore, the likelihood of cavitation and / or noise tends to be reduced.
[0066] At step s10, check valve 6 opens. In this embodiment, check valve 6 opens at some point after the liquid ring pump 10 is activated and the first valve 8 is opened. The delay between the activation of the liquid ring pump 10 and the full opening of check valve 6 can be a relatively short time, for example, less than or equal to ten seconds, or less than or equal to five seconds. The delay between the activation of the liquid ring pump 10 and the full opening of check valve 6 can be caused by check valve 6 sticking to the valve seat (i.e., stuck in the closed position) or by the pressure differential through check valve 6.
[0067] In this embodiment, the reduced gas pressure within chamber 102 caused by the activation of the liquid ring pump 10 tends to cause check valve 6 to open. In other words, the pressure differential across check valve 6 at step s10 tends to open check valve 6. With check valve 6 open, liquid ring pump 10 draws gas from facility 4 into liquid ring pump 10. This gas flow tends to hold check valve 6 in its open position.
[0068] Therefore, at step s10, the vacuum system 2 can draw gas from the facility 4 using the liquid ring pump 10 to establish a vacuum or low-pressure environment at the facility 4.
[0069] At step s12, the controller 20 controls the first valve 8 to close via the third connector 70, thereby preventing air from flowing into the gas inlet 108 via the air duct 36.
[0070] In some embodiments, the first valve 8 is closed for a predetermined period of time after it is opened (at step s6). This predetermined period of time can be any suitable time period, such as less than or equal to 15 seconds, or less than or equal to 10 seconds, or less than or equal to 5 seconds. For example, the predetermined period of time can be 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14s, or 15s. This advantageously tends to reduce noise. In some embodiments, a timer (e.g., a countdown timer) can be implemented to keep the first valve 8 open for the predetermined period of time.
[0071] In some embodiments, the first valve 8 is closed in response to the controller 20 detecting or determining that the check valve 6 is fully open. The controller 20 may determine or detect that the check valve 6 is fully open using measurements from sensors configured to measure the position or state of the check valve 6.
[0072] Therefore, an embodiment of the anti-cavitation process implemented by the vacuum system 2 is provided.
[0073] The method described above can be executed automatically under the control of the controller.
[0074] Check valves are advantageous in preventing or stopping unwanted backflow of gas and operating liquids, and are often particularly useful for liquid ring pumps operated using VFDs.
[0075] In the above embodiments, the vacuum system includes the above-referenced... Figure 1 The elements described above. However, in other embodiments, the vacuum system includes other elements that replace or supplement those described above. Furthermore, in other embodiments, some or all of the elements of the vacuum system may be connected in a suitable manner different from that described above. For example, in some embodiments, multiple liquid ring pumps may be implemented.
[0076] In the above embodiments, the check valve 6, the first valve 8, and the liquid ring pump 10 are separate, individual devices. However, in some embodiments, the liquid ring pump may have an integrated check valve, for example, in the inlet manifold of the liquid ring pump. In some embodiments, the liquid ring pump may have an integrated first valve, for example, in the inlet manifold of the liquid ring pump. In some embodiments, the liquid ring pump may have both an integrated check valve and an integrated first valve, for example, in the inlet manifold of the liquid ring pump.
[0077] An embodiment of a liquid ring pump 10 will now be described, which includes an inlet manifold with an integrated check valve 6. A first valve 8 is connected to the inlet manifold. For ease of understanding, the same reference numerals refer to the same elements. References below Figures 4 to 6 The liquid ring pump 10 described herein can be used as previously described in more detail above. Figure 3 The method is to control it.
[0078] Figure 4 This is a schematic diagram (not to scale) showing a cross-section of a liquid ring pump 10. The liquid ring pump 10 includes a housing 100, a chamber 102, a shaft 104, an impeller 106, and a gas inlet 108, as previously referenced above. Figure 2 Arranged as described in more detail. The gas inlet is connected to suction line 34 (in... Figure 4 (Not shown in the image).
[0079] In this embodiment, the liquid ring pump 10 includes an inlet manifold 300, a check valve 6 is integrated into the inlet manifold 300, and an air duct 36 is attached to the inlet manifold 300.
[0080] The check valve 6 includes an annular flange 601 defining a generally circular opening, a ball 602, and a retainer 603.
[0081] In this embodiment, an annular flange 601 is disposed on the inner side of the wall of the inlet manifold 300 at or near the inlet 108. The annular flange 601 includes a chamfered edge defining an opening. The chamfered ring serves as a valve seat. In this embodiment, the annular flange 601 is integrally formed with the wall of the inlet manifold 300.
[0082] In this embodiment, ball 602 is a generally spherical object disposed within inlet manifold 602. Ball 602 is movable between a first position and a second position, in which ball 602 is held by retainer 603 and does not block the opening (i.e., corresponding to the open position of check valve 6), and in the second position, ball 602 contacts annular flange 601 and thus blocks the opening (i.e., corresponding to the closed position of check valve 6). Therefore, in the first position, ball 602 is configured to allow fluid flow through the opening, and in the second position, ball 602 is configured to prevent or stop fluid flow through the opening. In other words, ball 602 can be used as a plug for the opening.
[0083] The retainer 603 is configured to retain the ball 602 when the ball 602 is in a first position. In this embodiment, the retainer 603 includes two protrusions (e.g., rods). The protrusions extend from the inner surface of the inlet manifold 300 into the interior of the inlet manifold 300 (i.e., the flow channel).
[0084] Air conduit 36 is connected to the air inlet of inlet manifold 300, which is located at a position after annular flange 601 (i.e., between annular flange 601 and chamber 102). Therefore, when ball 602 is in its second position, contacting annular flange 601 and blocking the opening, air (or other gas) can be introduced into chamber 102 via air conduit 36. First valve 8 is connected to air conduit 36 at or near inlet manifold 300.
[0085] Figure 4 This shows the state when vacuum system 2 is in its initial state (i.e., in Figure 3 The process is in step s2 of the liquid ring pump 10. Check valve 6 is closed and first valve 8 is closed. In the initial state, the gas pressure inside chamber 102 of liquid ring pump 10 is higher than the gas pressure inside suction line 34 and facility 4. The gas from inside chamber 102 of liquid ring pump 10 tends to flow back into suction line 34 due to the pressure difference. This gas flow... Figure 4 The arrow and reference numeral 400 indicate this. The gas flow 400 tends to move the ball 602 to its second position in contact with the annular flange 601, and the pressure difference through the ball 602 tends to keep the ball 602 against the annular flange 601. Therefore, the gas inlet 108 is blocked by the ball 602.
[0086] Figure 5 Shown in Figure 3 The process step s8 is the liquid ring pump 10. Figure 5 In this configuration, the liquid ring pump 10 is activated, the first valve 8 is open, and the check valve 6 remains closed. Furthermore, as in... Figure 5 As indicated by the arrow and reference numeral 500, air is drawn into the liquid ring pump 10 via the open first valve 8 and air conduit 36. In this embodiment, air 500 flows into chamber 102 after or downstream of the closed check valve 6 (i.e., after the annular flange 601 and the ball 602 in contact with it).
[0087] Figure 6 Shown in Figure 3 The process step s12 is the liquid ring pump 10. Figure 6 In this process, the liquid ring pump 10 is activated, the check valve 6 opens, and the first valve 8 closes. Furthermore, as in... Figure 6 As indicated by the arrow and reference numeral 600, the liquid ring pump 10 draws gas 600 from facility 4 into the liquid ring pump 10 via suction line 34. This gas flow tends to cause the retaining ball 602 to abut against retainer 603. The closed first valve 8 prevents air from flowing into inlet manifold 300 via air duct 36.
[0088] Therefore, an embodiment of a liquid ring pump is provided, which includes an inlet manifold with an integrated check valve.
[0089] The inlet manifold of a liquid ring pump with an integral or integrated check valve advantageously tends to reduce or eliminate the use of a separate piping section containing the check valve. This avoidance of a separate check valve piping section often means fewer connections (e.g., joints) between the liquid ring pump and the source of the gas pumped by the liquid ring pump. This correspondingly tends to reduce the overall installation height. Moreover, due to the fewer connections mentioned above, the risk of leakage tends to decrease. Therefore, the efficiency of the liquid ring pump tends to improve. Furthermore, the material costs associated with the liquid ring pump tend to decrease, for example, due to the reduction or elimination of the use of a separate piping section containing the check valve. In addition, the integration of the check valve also tends to prevent human error during the installation of the liquid ring pump in a location.
[0090] Furthermore, compared to check valves contained in separate piping sections, check valves integrated into the inlet manifold tend to restrict gas flow to a lesser extent.
[0091] In the above embodiments, the system includes a muffler. However, in other embodiments, the muffler is omitted.
[0092] In the above embodiments, air flows into the liquid ring pump via an air conduit and a first valve. However, in other embodiments, a different gas is introduced into the liquid ring pump. For example, an inert gas, such as nitrogen, can be used. In some embodiments, fluid (e.g., air) may be introduced into the liquid ring pump at a location different from that described above.
[0093] In the above embodiments, the check valve does not prevent or block airflow through the air duct to the liquid ring pump. In some embodiments, the check valve does not significantly affect the airflow through the air duct to the liquid ring pump, and the airflow is controlled only through the first valve. However, in other embodiments, the check valve may be configured such that when the check valve is in its closed position, the air duct is open to allow air to flow into the liquid ring pump through the air duct, and that when the check valve is in its open position, the air duct is closed by the check valve to prevent air from flowing into the liquid ring pump through the air duct.
[0094] In the above embodiments, the heat exchanger cools the operating liquid flowing through it. However, in other embodiments, in addition to the heat exchanger, other cooling devices are implemented to cool the operating liquid before it is received by the liquid ring pump.
[0095] In the above embodiments, a separator is implemented to recirculate the operating liquid back to the liquid ring pump. However, in other embodiments, different types of recirculation techniques are implemented. Recirculation of the operating liquid advantageously tends to reduce operating costs and water consumption. However, in some embodiments, recirculation of the operating liquid is not performed. For example, a vacuum system may include an open-loop operating liquid circulation system in which fresh operating liquid is supplied to the liquid ring pump and discharged operating liquid can be discarded. Therefore, a separator can be omitted.
[0096] In the above embodiments, the liquid ring pump is a single-stage liquid ring pump. However, in other embodiments, the liquid ring pump is a different type of liquid ring pump, such as a multi-stage liquid ring pump.
[0097] In the above embodiments, the operating liquid is water. However, in other embodiments, the operating liquid is a different type of operating liquid, such as oil.
[0098] The controller can be a proportional-integral (PI) controller, a proportional (P) controller, an integral (I) controller, a derivative (D) controller, a proportional-derivative (PD) controller, a proportional-integral-derivative (PID) controller, a fuzzy logic controller, or any other type of controller.
[0099] In the above embodiments, a single controller controls the operation of multiple system components (e.g., motors). However, in other embodiments, multiple controllers may be used, each controlling a corresponding subset of a set of components.
[0100] In the above embodiments, the pump is controlled to regulate or modulate the flow of the operating fluid into the liquid ring pump. However, in other embodiments, instead of or in addition to the pump, one or more different types of regulating devices are implemented, such as one or more valves for controlling the flow of the operating fluid. The controller may be configured to control the operation of said one or more regulating devices. In some embodiments, the operating fluid flow is not modulated or regulated, and the operating fluid flow is drawn by the vacuum inlet pressure of the pump.
[0101] List of reference numerals in the attached diagram: 2 - Vacuum system; 4 - Facilities; 6 - Check valve; 8 - First valve; 9 - Muffler; 10 - Liquid ring pump; 12 - Motor; 14 - Separator; 16 - Pump system; 18 - Heat exchanger; 20 - Controller; 34 - Suction tubing; 38 - Discharge pipeline; 40 - First operating liquid pipeline; 42 - System outlet pipeline; 44 - Another entrance; 46 - Second valve; 48 - Second operating liquid pipeline; 50 - Overflow pipe; 52 - Drain pipe; 54 - Third valve; 56 - Liquid level indicator; 58 - Third operating liquid pipeline; 60 - Coolant inlet; 62 - Coolant outlet; 66 - First connector; 68 - Second connector; 70 - Third connector; 100 - Casing; 102 - Chamber; 104 - Axis; 106 - Impeller; 108 - Gas Inlet; 201 - First frequency converter drive; 202 – Second frequency converter drive; 300 - Inlet manifold; 400 - Airflow; 500 – Airflow; 600 - Airflow; 601 - Annular flange; 602 – Ball; 603 – Holder.
Claims
1. A system comprising: Suction tubing; A liquid ring pump connected to the suction line, the liquid ring pump including a chamber and an impeller installed in the chamber; A check valve is arranged to allow fluid to flow into the chamber via the suction line and to prevent or stop fluid from flowing out of the chamber and into the suction line. A gas line is connected to the liquid ring pump so that gas can flow into the liquid ring pump via the gas line, the gas line being connected to the liquid ring pump between the check valve and the chamber; A valve is installed on the gas pipeline; as well as A controller configured to control the valve, wherein the controller is configured to open the valve for at least a certain period of time when the check valve is closed.
2. The system according to claim 1, wherein, The controller is configured to open the valve during a first predetermined time period starting from the activation of the liquid ring pump.
3. The system according to claim 1 or 2, wherein: The liquid ring pump also includes a shaft, and the impeller is mounted on the shaft; The system also includes a motor configured to drive the shaft; and The controller is configured to activate the liquid ring pump by controlling the motor to rotate the shaft.
4. The system according to claim 1 or 2, wherein, The controller is configured to close the valve after a second predetermined time period following the opening of the valve.
5. The system according to claim 1 or 2, wherein, The controller is configured to close the valve in response to determining that the check valve is open.
6. The system according to claim 1 or 2, wherein: The check valve is installed on the suction line; and The gas line is connected to the suction line between the check valve and the inlet of the liquid ring pump.
7. The system according to claim 1 or 2, wherein: The liquid ring pump includes an inlet manifold; The check valve is integrated into the inlet manifold; The gas line is connected to the inlet manifold between the chamber and the integrated check valve in its closed position.
8. The system according to claim 7, wherein The integrated check valve includes: An annular flange that defines the opening; as well as An object movable between a first position and a second position, wherein in the first position the object is positioned away from the opening so as not to obstruct the opening, and in the second position the object is adjacent to the annular flange so as to obstruct the opening; and The gas line is connected to the inlet manifold between the annular flange and the chamber.
9. The system according to claim 1 or 2 further includes a silencer disposed on the gas pipeline.
10. A liquid ring pump, comprising: Inlet manifold; as well as A chamber that is fluidly connected to the inlet manifold; in The inlet manifold includes: Integrated check valve; as well as A gas inlet is located between the integrated check valve and the chamber, which are in their closed position.
11. The liquid ring pump according to claim 10, wherein The integrated check valve includes: An annular flange that defines the opening; as well as An object movable between a first position and a second position, wherein in the first position the object is positioned away from the opening so as not to obstruct the opening, and in the second position the object is adjacent to the annular flange so as to obstruct the opening; and The gas inlet is located between the annular flange and the chamber.
12. A control method for a control system, said system being the system according to any one of claims 1 to 9, the method comprising: Activate the liquid ring pump; as well as After the liquid ring pump is activated and the check valve is closed, the valve is opened to allow gas to flow into the liquid ring pump via the gas line.
13. The method of claim 12, further comprising, thereafter: Close the valve; and Open the check valve.
14. The method according to claim 12 or 13, wherein, The gas is air or an inert gas.