Liquid ring pump control

Abstract

A system comprising: a liquid ring pump (10) comprising: a chamber (102); a suction inlet; a discharge outlet; and an operating liquid inlet; a gas line (36) coupled to the liquid ring pump (10); a valve (8) disposed on the gas line (36); a first sensor (81) configured to measure a first parameter of the inlet fluid; a second sensor (82) configured to measure a second parameter of the operating liquid, the discharge fluid, or a fluid within the chamber; and a controller (20) configured to: determine a vapor pressure of the operating liquid using the second parameter; and control operation of the valve (8) based on the first parameter and the vapor pressure.

Description

Technical Field

[0001] This invention relates to the control of liquid ring pumps. Background Technology

[0002] Liquid ring pumps are a known type of pump commonly used commercially as vacuum pumps and gas compressors. 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 a service fluid). As the drive system drives the shaft and impeller, a liquid ring forms on the inner wall of the chamber, providing a seal that isolates individual volumes between adjacent impeller blades. The impeller and shaft are positioned eccentrically relative to the liquid ring, resulting in a cyclical change in the enclosed volume between adjacent impeller blades 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 adjacent impeller blades, resulting in a lower pressure therein. This allows the portion where the liquid ring is further away from the shaft to be used as an intake zone. In the portion of the chamber where the liquid ring is closer to the shaft, there is a smaller volume between adjacent impeller blades, resulting in a higher pressure therein. This allows the portion where the liquid ring is closer to the shaft to be used as a gas 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] Cavitation is often a significant cause of wear and failure in some liquid ring pumps, especially those operating under low-pressure / high-vacuum conditions. Furthermore, cavitation can lead to interfering noise. Therefore, it is desirable to prevent or eliminate startup cavitation in liquid ring vacuum pumps.

[0007] The inventors have recognized that cavitation can be reduced or eliminated by introducing an airflow into the inlet manifold of the liquid ring pump.

[0008] In one aspect, a system is provided comprising: a liquid ring pump including a chamber, a suction inlet, a discharge outlet, and an operating liquid inlet, wherein the liquid ring pump is configured to pump inlet fluid into the chamber via the suction inlet, pump discharge fluid out of the chamber via the discharge outlet, and receive operating liquid into the chamber via the operating liquid inlet; a gas line connected to the liquid ring pump such that gas can flow into the chamber of the liquid ring pump via the gas line; a valve disposed on the gas line; a first sensor configured to measure a first parameter of the inlet fluid; a second sensor configured to measure a second parameter of a fluid selected from a fluid group including the operating liquid, the discharge fluid, and fluid in the chamber; and a controller configured to determine a vapor pressure of the operating liquid using the measured value of the second parameter, and to control the operation of the valve based on the measured value of the first parameter and the determined vapor pressure.

[0009] The first parameter can be pressure. The second parameter can be temperature.

[0010] The controller can be configured to determine the vapor pressure of the operating liquid using the Antoine formula. The controller can be configured to compare a measured value of a first parameter with the determined vapor pressure and control valve operation based on this comparison. The controller can be configured to determine the difference between the measured value of the first parameter and the determined vapor pressure and control valve operation based on the determined difference. The controller can be configured to compare the determined difference with a threshold value and control valve operation based on this comparison. The controller can be configured to: control the valve to close or remain closed if the determined difference is greater than the threshold value; and control the valve to open or remain open if the determined difference is less than or equal to the threshold value. The controller can be configured to control valve operation such that the degree of valve opening depends on the determined difference between the measured value of the first parameter and the determined vapor pressure.

[0011] The system may also include a suction line connected to the suction inlet and a check valve disposed on the suction line. The check valve may be 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 into the suction line. A gas line may be connected to the suction line between the check valve and the suction inlet of the liquid ring pump. A first sensor may be connected to the suction line between the check valve and the suction inlet of the liquid ring pump.

[0012] A liquid ring pump may include an inlet manifold. Valves may be integrated into the inlet manifold.

[0013] The gas can be air or an inert gas.

[0014] The system may also include: a discharge line connected to the discharge outlet; and / or an operating liquid line connected to the discharge operating liquid inlet. A second sensor may be connected to the discharge line or the operating liquid line.

[0015] In another aspect, a control method is provided for controlling the system, the system including a liquid ring pump, a gas line, and a valve disposed on the gas line, wherein the liquid ring pump includes a chamber, a suction inlet, a discharge outlet, and an operating liquid inlet, the liquid ring pump being configured to pump inlet fluid into the chamber via the suction inlet, pump discharge fluid out of the chamber via the discharge outlet, and receive operating liquid into the chamber via the operating liquid inlet, and the gas line being connected to the liquid ring pump such that gas can flow into the chamber of the liquid ring pump via the gas line, the method comprising: measuring a first parameter of the inlet fluid; measuring a second parameter of a fluid selected from a group of fluids including the operating liquid, the discharge fluid, and fluid in the chamber; determining a vapor pressure of the operating liquid using the measured value of the second parameter; and controlling the operation of the valve based on the measured value of the first parameter and the determined vapor pressure. Attached Figure Description

[0016] 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 some steps of a process that can be performed by a vacuum system. Detailed Implementation

[0017] Figure 1 This 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 drawing gas (e.g., air) from facility 4.

[0018] 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, a controller 20, a first sensor 81, and a second sensor 82.

[0019] Facility 4 is connected to the gas inlet of liquid ring pump 10 via a suction or vacuum line or pipe 34.

[0020] In this embodiment, check valve 6 is disposed on suction line 34. First sensor 81 is also disposed on suction line 34. Check valve 6 is disposed between facility 4 and first sensor 81. First sensor 81 is disposed between check valve 6 and liquid ring pump 10.

[0021] 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 stop fluid from flowing in the opposite direction, i.e., from liquid ring pump 10 to facility 4.

[0022] In this embodiment, the first sensor 81 is a pressure sensor. The first sensor 81 is configured to measure the pressure of the gas flowing in the suction line 34, i.e., the pressure of the gas pumped from the facility 4 by the action of the liquid ring pump 10. The first sensor 81 can be any suitable type of pressure sensor. The first sensor 81 is connected to the controller 20 via a first sensor connection 83, such that the measurement value obtained by the first sensor 81 is transmitted from the first sensor 81 to the controller 20. The first sensor connection 83 can be any suitable type of connection, including but not limited to wired or fiber optic connections, or wireless connections.

[0023] The gas inlet of the liquid ring pump 10 is also connected to an air (or gas) pipe 36 (which may also be referred to as an air (or gas) line), through which air can be supplied to the gas inlet of the liquid ring pump 10. In this embodiment, the air pipe 36 is connected between the first sensor 81 and the gas inlet of the liquid ring pump 10 to a suction line 34.

[0024] In this embodiment, the check valve 6 does not prevent or block air from flowing to the liquid ring pump 10 via the air pipe 36. The air pipe 36 can be considered to bypass the check valve 6.

[0025] The first valve 8 is installed on the air pipe 36. The silencer 9 is installed on the air pipe 36. The first valve 8 is located between the suction line 34 and the silencer 9. The silencer 9 is located between the first valve 8 and the inlet of the suction line 34.

[0026] The first valve 8 can be a solenoid valve.

[0027] The silencer 9 can also be called a muffler. The silencer 9 is an acoustic device configured to reduce the loudness of the sound pressure within the air pipe 36 generated by the liquid ring pump 10 that draws in air through the air pipe 36.

[0028] In this embodiment, the liquid ring pump 10 is a single-stage liquid ring pump.

[0029] 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 exhaust 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.

[0030] Figure 2This is a schematic cross-section of an exemplary liquid ring pump 10 (not to scale). The remainder of the vacuum system 2 will be described later. Figure 2 The liquid ring pump 10 shown will be described in more detail later.

[0031] In this embodiment, the liquid ring pump 10 includes a housing 100 defining a substantially cylindrical chamber 102, a shaft 104 extending into the chamber 102, and an impeller 106 fixedly mounted to the shaft 104. The gas inlet 108 of the liquid ring pump 10 (which is coupled to a suction line 34) is fluidly connected to the air inlet of the chamber 102. The gas outlet of the liquid ring pump 10 (… Figure 2 (Not shown) The gas output is fluidly connected to chamber 102.

[0032] During operation of the liquid ring pump 10, the operating fluid is received in the chamber 102 via a first operating fluid line 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, causing the impeller 106 to rotate within the chamber 102. As the impeller 106 rotates, the operating fluid (not shown) in the chamber 102 is forced against the wall of the chamber 102, forming a liquid ring that seals and isolates individual volumes between adjacent impeller blades. Moreover, gas (such as air) is drawn into the chamber 102 from the suction line 34 via a gas inlet 108 and an air inlet to the chamber 102. This gas flows into the volume formed between adjacent blades of the impeller 106. As the gas moves from the air inlet to the gas outlet of the chamber 102, the rotation of the impeller 106 compresses the gas contained within the volume, and at the gas outlet, the 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.

[0033] Now back 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.

[0034] 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.

[0035] 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.

[0036] In this embodiment, separator 14 includes another inlet 44 through which separator 14 can receive an additional or "supplementary" supply of operating liquid from an operating liquid source (not shown). A second valve 46 is disposed along the other inlet 44. The second valve 46 is configured to control the flow rate of the additional operating liquid entering separator 14 via the other inlet 44. The second valve 46 may be a solenoid valve.

[0037] 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 line 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 line 50, which provides an outlet for excess operating liquid. A third operating liquid outlet of the separator 14 is connected to a drain or vent line 52, which provides a line through which the separator can discharge operating liquid. A third valve 54 is provided along the vent line 52. The third valve 54 is configured to be open or closed, thereby allowing or preventing operating liquid from flowing out of the separator 14 via the vent line 52, respectively. The third valve 54 may be a solenoid valve.

[0038] The separator 14 also includes a level indicator 56 configured to provide an indication of the amount of operating liquid in the separator 14 to a human user, such as a 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.

[0039] In this embodiment, in addition to being connected to the separator 14 via a second operating liquid line 48, the pump system 16 is connected to the heat exchanger 18 via a third operating liquid line 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 line 48 and to pump the operating liquid to the heat exchanger 18 via the third operating liquid line 58.

[0040] The heat exchanger 18 is configured to receive a relatively hot operating liquid from the pump system 16, cool the relatively hot operating liquid to provide a relatively cold operating liquid, and output the relatively cold operating liquid.

[0041] In this embodiment, heat exchanger 18 is configured to cool the relatively hot operating liquid flowing through it by transferring heat from the relatively hot operating liquid to a fluid coolant also flowing through it. 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) through coolant inlet 60. Heat exchanger 18 discharges coolant (to which heat has been transferred) through coolant outlet 62.

[0042] 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 coupled to a first operating liquid line 40. Thus, the heat exchanger 18 is connected to the liquid ring pump 10 via the first operating liquid line 40, such that during operation, cooled operating liquid is pumped from the heat exchanger 18 to the liquid ring pump 10 by the pump system 16.

[0043] A second sensor 82 is connected between the heat exchanger 18 and the liquid ring pump 10 to the first operating liquid line 40. The second sensor 82 is a temperature sensor. The second sensor 82 is configured to measure the temperature of the operating liquid flowing into (i.e., pumped to) the liquid ring pump 10 via the first operating liquid line 40. The second sensor 82 can be any suitable type of temperature sensor. The second sensor 82 is connected to the controller 20 via a second sensor connection 84, such that the measured value obtained by the second sensor 82 is transmitted from the second sensor 82 to the controller 20. The second sensor connection 84 can be any suitable type of connection, including but not limited to wired or fiber optic connections, or wireless connections.

[0044] 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.

[0045] The controller 20 is connected to the motor 12 via a first VFD 201 and a first connection 66, so that control signals for controlling the motor 12 can be sent from the controller 20 to the motor 12. The first connection 66 can be any suitable type of connection, including but not limited to wired or fiber optic connections, or wireless connections. The motor 12 is configured to operate according to the control signals it receives from the controller 20.

[0046] Controller 20 is connected to pump system 16 via a second VFD 202 and a second connection 68, such that control signals for controlling pump system 16 can be transmitted from controller 20 to the motor of pump system 16. The second connection 68 can be any suitable type of connection, including but not limited to wired or fiber optic connections, or wireless connections. Pump system 16 is configured to operate according to the control signals it receives from controller 20.

[0047] The controller 20 is also connected to the first valve 8 via a third connection 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 connection 70 can be any suitable type of connection, including but not limited to wired or fiber optic connections, or wireless connections. The first valve 8 is configured to operate according to the control signals it receives from the controller 20. The control of the first valve 8 by the controller 20 will be described in the following reference. Figure 3 This will be described in more detail later. In this embodiment, the controller 20 controls the first valve 8 based on sensor measurements received from the first sensor 81 and the second sensor 82.

[0048] The controller 20 can also be connected to the second valve 46 and the third valve 54 via corresponding connections (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.

[0049] Therefore, an embodiment of vacuum system 2 is provided.

[0050] The means for implementing the above arrangement and performing the method steps described below can be provided by configuring or adapting any suitable device, such as one or more computers or other processing devices or processors, and / or by providing additional modules, including controller 20. The means may include a computer, a network of computers, or one or more processors for implementing instructions and using data, including instructions and data in the form of a computer program or multiple computer programs stored in or on a machine-readable storage medium such as computer memory, computer disk, ROM, PROM, etc., or any combination of such or other storage media.

[0051] Now refer to Figure 3 An embodiment describing a control process that can be executed by vacuum system 2. Note that details may be omitted. Figure 3 The process steps depicted in the flowchart and described below may be presented differently from those shown below. Figure 3 These process steps are performed in the order shown. Furthermore, although all process steps have been depicted as discrete, sequential steps for convenience and ease of understanding, some of these process steps may actually be performed simultaneously or at least overlap in time.

[0052] Figure 3 This is a process flow diagram illustrating some steps of an embodiment of the control process implemented by the vacuum system 2.

[0053] In this embodiment, in Figure 3During the process, the liquid ring pump 10 is "on", that is, the liquid ring pump 10 is activated to pump gas from facility 4.

[0054] At step s2, the first sensor 81 measures the first pressure P1, which is the pressure of the gas flowing in the suction line 34, i.e., the pressure of the gas pumped from facility 4 by the action of liquid ring pump 10.

[0055] In step s4, the first sensor 81 sends the first pressure measurement value P1 to the controller 20 via the first sensor connection 83.

[0056] At step s6, the second sensor 82 measures the first temperature T1. The first temperature T1 is the temperature of the operating liquid received by the liquid ring pump 10 via the first operating liquid pipe 40.

[0057] At step s8, the second sensor 82 sends the first temperature measurement value T1 to the controller 20 via the second sensor connection 84.

[0058] At step s10, the controller 20 uses the measured first temperature T1 to calculate, determine, or estimate the vapor pressure (also referred to as saturation pressure) of the operating liquid in the liquid ring pump 10. In this embodiment, the operating liquid is water, and therefore, the controller 20 determines the vapor pressure of water at the first temperature T1, which is referred to below as "water vapor pressure P". wv In this embodiment, an approximate formula, particularly the Antoine equation, is used to determine the water vapor pressure P. wv Water vapor pressure P wv It was identified as: Where: A is a known constant value of the controller 20. For example, A could be 7.07406; B is a known constant value of the controller 20. For example, B could be 1657.46; C is a known constant value of controller 20. For example, C could be 227.02; and It is the first temperature measured.

[0059] In some embodiments, one or more of parameters A, B, and C may have values ​​different from those given above.

[0060] In some embodiments, the controller 20 may optionally add a so-called offset value to a defined water vapor pressure P. wv Furthermore, this value can be used in subsequent steps. In other words, controller 20 can calculate and use updated pressure values. ,in This is the offset value. Offset value This can be considered a safety margin. Offset value It can be any suitable value, including but not limited to values ​​between 1 mbar and 10 mbar, such as 1 mbar, 2 mbar, 3 mbar, 4 mbar, 5 mbar, 6 mbar, 7 mbar, 8 mbar, 9 mbar, or 10 mbar. In some embodiments, the offset value is omitted. The use of.

[0061] At step s12, the controller 20 calculates the water vapor pressure P. wv It is compared with the first pressure measurement value P1. For example, the controller 20 can determine the calculated water vapor pressure P. wv The difference between the first pressure measurement value P1 and ,Right now, .

[0062] In this embodiment, if The magnitude is less than or equal to the predetermined pressure threshold. (i.e., if) If the controller 20 determines that the inlet pressure P1 of the liquid ring pump 10 is close to (i.e., within the threshold distance)..., then the method proceeds to step s14. In other words, if the controller 20 determines that the inlet pressure P1 of the liquid ring pump 10 is close to (i.e., within the threshold distance)... Internal water vapor pressure Then the method proceeds to step s14.

[0063] On the other hand, if The magnitude is greater than the predetermined pressure threshold (i.e., if) If the controller 20 determines that the inlet pressure P1 of the liquid ring pump 10 is not close to the water vapor pressure, then the method proceeds to step s18. In other words, if the controller 20 determines that the inlet pressure P1 of the liquid ring pump 10 is not close to the water vapor pressure... Then the method proceeds to step s18. After describing steps s14-s16, step s18 will be described in more detail below.

[0064] Predetermined pressure threshold This can be any suitable value, such as 20 millibars. Predetermined pressure threshold. It can be adjustable or variable.

[0065] In step s14, in response to determining The magnitude is less than or equal to the predetermined pressure threshold. The controller 20 controls the first valve 8 to open (or remain open if it is already open) via the third connection 70.

[0066] At step s16, the liquid ring pump 10 draws air into chamber 102 via its gas inlet 108. Air is drawn into the liquid ring pump 10 through air pipe 36, the open first valve 8, and the silencer 9. Due to the reduced gas pressure within chamber 102 caused by the operation of the liquid ring pump 10, air tends to be drawn into the liquid ring pump 10 through air pipe 36. The silencer 9 tends to reduce the noise associated with the liquid ring pump 10 drawing air in through air pipe 36.

[0067] Introducing air into the liquid ring pump 10 at step s16 advantageously tends to cause an increase in the fluid pressure within the liquid ring pump 10, and therefore, the first pressure P1 measured by the first sensor 81 tends to increase. Therefore, the error value... It tends to increase.

[0068] Increase error value This means the first pressure P1 and the water vapor pressure The difference between them increases. In other words, the pressure of the gas received by the liquid ring pump is reduced from the water vapor pressure. Remove it. This advantageously tends to reduce the possibility of cavitation caused by the inlet gas in the liquid ring pump 10.

[0069] After step s16, Figure 3 The process is repeated, for example, until vacuum system 2 is shut down. Figure 3 The process can be performed continuously, or more preferably continuously during the operation of the vacuum system 2.

[0070] Now return to step s12 where controller 20 determines. The magnitude is greater than the predetermined pressure threshold In the case of step s18, controller 20 controls the first valve 8 to close via the third connection 70 (or remains closed if it is already closed).

[0071] Therefore, air is not drawn into the chamber 102 of the liquid ring pump 10 via the air pipe 36. Consequently, the pressure of the fluid in the liquid ring pump does not increase due to the introduction of air into the chamber 102.

[0072] Therefore, an embodiment of an anti-cavitation process implemented by vacuum system 2 is provided.

[0073] The method described above can be executed automatically under the control of the controller.

[0074] Advantageously, the system and second control process described above tend to allow control of the fluid temperature and pressure within the liquid ring pump.

[0075] The system and second control process described above advantageously tend to provide improved reliability for the liquid ring pump.

[0076] The system and second control process described above advantageously tend to reduce the likelihood and / or severity of cavitation in the liquid ring pump. For example, cavitation can be caused in the liquid ring pump by the inlet pressure (i.e., the pressure of the gas from the suction line) being at or below the vapor pressure of the operating liquid in the pump. The second control process described above advantageously tends to regulate the inlet pressure to move it away from the vapor pressure of the operating liquid, thereby reducing the likelihood of cavitation. Therefore, damage to the liquid ring pump caused by cavitation tends to be reduced or eliminated.

[0077] Check valves are advantageous in preventing or stopping unwanted backflow of gas and operating liquid, and are particularly beneficial for liquid ring pumps operating with VFDs.

[0078] 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 elements that replace or are not included in addition to those described above. Furthermore, in other embodiments, some or all of the elements of the vacuum system may be connected together in a different manner than that described above. For example, in some embodiments, multiple liquid ring pumps may be implemented.

[0079] 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.

[0080] The inlet manifold of a liquid ring pump with an integral or integrated check valve and / or first valve advantageously tends to reduce or eliminate the use of separate piping sections containing the check valve and / or first valve. This avoidance of separate check valve and / or first valve piping sections often means, for example, fewer connections (e.g., joints) between the liquid ring pump and the gas source pumped by the liquid ring pump. This, in turn, tends to reduce the overall installation dimensions, such as 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 increase. Furthermore, the material costs associated with the liquid ring pump tend to decrease, for example, because of the reduction or elimination of the use of separate piping sections containing valves. In addition, the integration of the check valve and / or first valve also tends to prevent human error during the installation of the liquid ring pump in one position.

[0081] Furthermore, compared to check valves contained in separate pipe sections, check valves and / or first valves integrated in the inlet manifold advantageously tend to restrict gas flow to a lesser extent.

[0082] In the above embodiments, the system includes a muffler. However, in other embodiments, the muffler is omitted.

[0083] In the above embodiments, air is introduced into the liquid ring pump via an air pipe 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, the fluid (e.g., air) may be introduced into the liquid ring pump at a location different from that described above.

[0084] In the above embodiments, the check valve does not prevent or block the flow of air to the liquid ring pump via the air line. In some embodiments, the check valve does not significantly affect the airflow to the liquid ring pump via the air line, and this airflow is controlled only by 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 line is open, allowing air to flow into the liquid ring pump via the air line, and such that when the check valve is in its open position, the air line is closed by the check valve, preventing air from flowing into the liquid ring pump via the air line.

[0085] In the above embodiments, a heat exchanger cools the operating liquid flowing through it. However, in other embodiments, instead of a heat exchanger or in addition to a heat exchanger, other cooling devices are implemented to cool the operating liquid before it is received by the liquid ring pump.

[0086] 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. Operating liquid recirculation advantageously tends to reduce operating costs and water usage. However, in some embodiments, operating liquid recirculation is not performed. For example, a vacuum system may include an open-loop operating liquid circulation system, wherein fresh operating liquid is supplied to the liquid ring pump, and discharged operating liquid can be discarded. Therefore, a separator can be omitted.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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 the component group.

[0091] In the above embodiments, the pump is controlled to regulate or adjust the flow rate of the operating fluid entering the liquid ring pump. However, in other embodiments, instead of the pump 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 rate of the operating fluid. The controller may be configured to control the operation of one or more regulating devices. In some embodiments, the operating fluid flow rate is not regulated or adjusted and is drawn by the vacuum inlet pressure of the pump.

[0092] In the above embodiments, the Antoine equation is used to estimate the water vapor pressure P. wv However, in other embodiments, the water vapor pressure is calculated, determined, estimated, or determined in different appropriate ways, for example, by using different approximations such as the August-Roche-Magnus (or Magnus-Tetens or Magnus) equation, the Tetens equation, the Buck equation, or the Goff-Gratch equation.

[0093] In the above embodiment, based on the first temperature measured by the second sensor... Determine water vapor pressure A second sensor is coupled to the first operating liquid line between the heat exchanger and the liquid ring pump. In other embodiments, the second sensor has a different location. For example, the second sensor may be inside or integrated with the liquid ring pump and arranged to measure the temperature of the operating liquid within the liquid ring pump. In some embodiments, the measurement is based on a different temperature, i.e., a temperature different from the operating liquid temperature received by the liquid ring pump. Determine the water vapor pressure For example, in some embodiments, the controller 20 uses the measured temperature of the discharge fluid from the liquid ring pump 10 flowing in the discharge line 38—that is, the temperature of the air-water mixture pumped by the liquid ring pump 10 to the separator 14—to determine or estimate the vapor pressure of the operating liquid in the liquid ring pump 10. This temperature of the discharge fluid from the liquid ring pump 10 flowing in the discharge line 38 can be measured by a temperature sensor coupled to the discharge line 38 between the liquid ring pump 10 and the separator 14. This temperature sensor can be of any suitable type and can be connected to the controller 20 via any suitable type of connection, including but not limited to wired or fiber optic or wireless connections.

[0094] In the above embodiments, the error value Determined to be However, in other embodiments, the error value is determined in a different way, for example, using different appropriate formulas. For instance, the error value could be the first pressure. and / or water vapor pressure and / or the first temperature Different functions. In some embodiments, weights may be applied to the measured pressure. and / or water vapor pressure .

[0095] List of reference numerals in the attached diagram: 2-Vacuum system; 4- Facilities; 6-Check valve; 8-First valve; 9-Silencer; 10-Liquid ring pump; 12-Motor; 14-Separator; 16-Pump system; 18-Heat exchanger; 20-Controller; 34 - Suction tubing; 36-Air Tube 38 - Discharge pipeline; 40 - First operating liquid tube; 42 - System outlet pipe; 44 - Another entrance; 46 - Second valve; 48-Second operating liquid tube; 50 - Overflow pipe; 52-Drain pipe; 54 - Third valve; 56 - Liquid level indicator; 58-Third operating liquid tube; 60 - Coolant inlet; 62 - Coolant outlet; 66 - First connection; 68-Second connection; 70 - Third connection; 81 - First sensor; 82 - Second sensor; 83 - First sensor connection; 84 - Second sensor connection; 100 - Housing; 102-chamber; 104-axis; 106 - Impeller; 108 - Gas Inlet.

[0096] 201 - First frequency converter drive; 202 - Second frequency converter drive.

Claims

1. A vacuum system, the vacuum system comprising: Liquid ring pump, the liquid ring pump comprising: Chamber; Suction inlet; Emission outlets; and Operate the liquid inlet; among which The liquid ring pump is configured to: The inlet fluid is pumped into the chamber via the suction inlet; The discharge fluid is pumped out of the chamber via the discharge outlet; and The operating fluid is received into the chamber via the operating fluid inlet; A gas line is connected to the liquid ring pump, allowing gas to flow into the chamber of the liquid ring pump via the gas line; Valves installed on the gas pipeline; A first sensor, configured to measure a first parameter of the inlet fluid; A second sensor, configured to measure a second parameter of a fluid selected from a fluid group including the operating liquid, the discharge fluid, and the fluid within the chamber; and The controller is configured as follows: The vapor pressure of the operating liquid is determined using the measured value of the second parameter; and The operation of the valve is controlled based on the measured value of the first parameter and the determined vapor pressure.

2. The vacuum system according to claim 1, wherein, The first parameter is pressure.

3. The vacuum system according to claim 1 or 2, wherein, The second parameter is temperature.

4. The vacuum system according to claim 1 or 2, wherein, The controller is configured to use the Antoine formula to determine the vapor pressure of the operating liquid.

5. The vacuum system according to claim 1 or 2, wherein, The controller is configured to compare the measured value of the first parameter with the determined vapor pressure, and to control the operation of the valve based on the comparison.

6. The vacuum system according to claim 1 or 2, wherein, The controller is configured to determine the difference between a measured value of the first parameter and a determined vapor pressure, and to control the operation of the valve based on the determined difference.

7. The vacuum system according to claim 6, wherein, The controller is configured to compare the determined difference with a threshold and control the operation of the valve based on the comparison.

8. The vacuum system according to claim 7, wherein, The controller is configured to: If the determined difference is greater than the threshold, the valve is controlled to close or remain closed; and If the determined difference is less than or equal to the threshold, the valve is controlled to open or remain open.

9. The vacuum system according to claim 6, wherein, The controller is configured to control the operation of the valve such that the degree to which the valve is opened depends on a determined difference between a measured value of the first parameter and a determined vapor pressure.

10. The vacuum system according to claim 1 or 2, further comprising: A suction line connected to the suction inlet; as well as A check valve installed on the suction line; in The 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 into the suction line; and The gas line is connected to the suction line between the check valve and the suction inlet of the liquid ring pump.

11. The vacuum system according to claim 10, wherein, The first sensor is connected to the suction line between the check valve and the suction inlet of the liquid ring pump.

12. The system according to claim 1 or 2, wherein: The liquid ring pump includes an inlet manifold; and The valve is integrated into the inlet manifold.

13. The vacuum system according to claim 1 or 2, wherein the gas is air or an inert gas.

14. The vacuum system according to claim 1 or 2, further comprising: The discharge pipeline connected to the discharge outlet; and / or An operating liquid line is connected to the operating liquid inlet; in The second sensor is connected to the discharge line or the operating liquid line.

15. A control method for controlling a vacuum system, the vacuum system comprising a liquid ring pump, a gas line, and a valve disposed on the gas line, wherein the liquid ring pump comprises a chamber, a suction inlet, a discharge outlet, and an operating liquid inlet, the liquid ring pump being configured to pump inlet fluid into the chamber via the suction inlet, pump discharge fluid out of the chamber via the discharge outlet, and receive operating liquid into the chamber via the operating liquid inlet, and the gas line being connected to the liquid ring pump such that gas can flow into the chamber of the liquid ring pump via the gas line, the method comprising: Measure the first parameter of the inlet fluid; Measure a second parameter of the fluid selected from the fluid group including the operating liquid, the discharge fluid, and the fluid in the chamber; The vapor pressure of the operating liquid is determined using the measured value of the second parameter; as well as The operation of the valve is controlled based on the measured value of the first parameter and the determined vapor pressure.

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