A water pump anti-cavitation system and anti-cavitation method

Abstract

The present application relates to a kind of water pump anti-cavitation system and anti-cavitation method, water pump anti-cavitation system includes: expansion water tank;Inert gas storage device, for storing compressed inert gas;The inert gas storage device includes the gas cylinder of storage compressed inert gas and is arranged between the decompression device of gas cylinder and expansion water tank;Pressure regulating device is used to adjust the gas pressure in expansion water tank;Pressure regulating device includes first solenoid valve and second solenoid valve, first solenoid valve is arranged on the pressure release port of expansion water tank, second solenoid valve is arranged on the gas path between inert gas source and expansion water tank;Pressure detection device is used to detect the system pressure of water pump inlet side;Controller is electrically connected with pressure detection device and pressure regulating device.The present application can realize the water pump anti-cavitation protection of flexible adaptation to different environment, real-time response pressure change, simple and reliable structure, maintenance convenient and with abnormal self-diagnosis function.

Description

Technical Field

[0001] This invention relates to the field of fluid transport technology, and in particular to a water pump anti-cavitation system and anti-cavitation method. Background Technology

[0002] Pump cavitation is a common fault in HVAC and fluid transport systems. When the pump inlet pressure is lower than the saturated vapor pressure of the transported medium, the liquid vaporizes to produce bubbles. These bubbles collapse in the high-pressure zone, causing impact erosion on components such as the impeller. This leads to decreased pump efficiency, blade damage, increased vibration and noise, and in severe cases, even pump failure. Existing anti-cavitation technologies mainly include increasing the pump inlet pressure, structural improvement, booster venting devices, and flow control. However, these methods all have significant limitations: increasing the pump inlet pressure requires a large installation space and cannot dynamically respond to pressure fluctuations; structural improvements are costly and have limited applicability; booster venting devices are complex in structure and pose risks of air bladder aging and medium reaction; and flow control comes at the cost of sacrificing operating efficiency.

[0003] Existing technical solutions struggle to balance versatility, dynamic response capability, and structural simplicity. For different media compositions and temperatures, a large pre-pump pressure margin is often required, which increases the overall system's pressure requirements. While expansion tanks and other pressurization devices can absorb pressure fluctuations, they suffer from issues such as aging of the inner liner, limited expansion capacity, and maintenance difficulties. Furthermore, air pressurization can easily lead to pipe oxidation or reactions with antifreeze components. Traditional pressurization methods cannot dynamically adjust according to real-time operating conditions, making it difficult to respond quickly to system pressure fluctuations, often resulting in frequent pump start-stops or continuous operation in cavitation risk zones.

[0004] Therefore, there is an urgent need for a water pump anti-cavitation system and method to address the shortcomings of existing technologies. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a water pump anti-cavitation system and anti-cavitation method, which can realize water pump anti-cavitation protection that can flexibly adapt to different environments, respond to pressure changes in real time, has a simple and reliable structure, is easy to maintain, and has an abnormal self-diagnosis function.

[0006] To solve the above-mentioned technical problems, the present invention provides a water pump anti-cavitation system, comprising: Expansion tanks are used to store circulating water and provide pressure stabilization space. An inert gas storage device for storing compressed inert gas; the inert gas storage device includes a gas cylinder for storing compressed inert gas and a pressure reducing device disposed between the gas cylinder and an expansion tank. A pressure regulating device is used to regulate the gas pressure in the expansion tank; the pressure regulating device includes a first solenoid valve and a second solenoid valve, the first solenoid valve is disposed on the pressure relief port of the expansion tank, and the second solenoid valve is disposed on the gas line between the inert gas source and the expansion tank. A pressure detection device is used to detect the system pressure at the inlet side of the water pump; The controller, electrically connected to the pressure detection device and the pressure regulating device, is used to control the operation of the pressure regulating device based on feedback from the pressure detection device to maintain the pressure at the pump inlet side above the cavitation critical pressure. The controller is configured to: control the pressure regulating device to inject inert gas into the expansion tank when the pressure detection value is lower than a first set threshold; control the pressure regulating device to release the pressure in the expansion tank when the pressure detection value is higher than a second set threshold; and issue an alarm signal when the operation frequency of the pressure regulating device exceeds a preset number of times within a set time.

[0007] Furthermore, the expansion tank is equipped with a pressurization interface and a water system interface; the pressurization interface is connected to an inert gas source; and the water system interface is connected to the inlet pipe of the water pump.

[0008] Furthermore, it also includes a level gauge for monitoring the liquid level inside the expansion tank.

[0009] Furthermore, the pressure reducing device is a pressure reducing valve.

[0010] Furthermore, the pressure detection device is a pressure sensor arranged at the water pump inlet.

[0011] Furthermore, it also includes a one-way gas valve, which is installed in the gas path between the inert gas source and the expansion tank.

[0012] Furthermore, it also includes a safety valve, which is installed on the expansion tank.

[0013] Furthermore, the first set threshold is determined based on the required net positive suction head (NPSH) of the water pump and the saturated vapor pressure of the medium; the second set threshold is determined based on the system's pressure-bearing capacity.

[0014] Secondly, in order to solve the above-mentioned technical problems, the present invention provides a method for preventing cavitation in water pumps, comprising the following steps: Detect the pressure at the inlet side of the water pump; When the pressure is lower than the pressure required to prevent cavitation, inert gas is injected into the expansion tank that is in fluid communication with the pump inlet side to increase the pressure on the pump inlet side; when the pressure exceeds the safety limit, the gas pressure in the expansion tank is released. During the stage of replenishing water to the expansion tank, the inflation action of the expansion tank is blocked. Monitor the trigger frequency of dynamic voltage regulation. If the frequency exceeds a preset number of times within a set time, the system is deemed to be abnormal.

[0015] Furthermore, the inert gas charging rate or charging pressure is dynamically adjusted based on the pressure detection results at the water pump inlet.

[0016] Compared with the prior art, the above-described technical solution of the present invention has the following advantages: The anti-cavitation system for water pumps described in this invention achieves multiple technical benefits, including dynamic pressure regulation, oxidation protection, simplified structure and reduced cost, improved reliability, and self-diagnosis of anomalies, through the coordinated operation of an expansion tank, inert gas storage device, pressure regulating device, pressure detection device, and controller. The system uses inert gas as the pressure regulating medium. The controller monitors the pump inlet pressure in real time and automatically triggers inflation or depressurization actions, ensuring the pump inlet pressure is always maintained above the critical cavitation pressure, fundamentally preventing cavitation. Using inert gas instead of traditional air or the gas bladder of the expansion tank avoids pipe corrosion and chemical reactions caused by oxygen contact with the system medium, extending the system's service life. The direct gas pressurization method eliminates vulnerable elastic components, and the nitrogen cylinder can be replaced at any time, facilitating maintenance. Furthermore, by monitoring the trigger frequency of the pressure regulating device, system leaks or valve malfunctions can be detected promptly, enabling predictive maintenance and preventing sudden shutdowns.

[0017] The water pump anti-cavitation method of the present invention achieves the technical effects of real-time response, adaptive operation, fault early warning, and wide applicability by coordinating steps such as detecting the water pump inlet pressure, dynamically charging or releasing inert gas, shielding during the water replenishment stage, and monitoring abnormal frequencies: pressure detection and adjustment actions form a closed-loop control, which can quickly compensate for pressure fluctuations and avoid downtime for adjustment; the automatic shielding of the air charging action during the water replenishment stage effectively prevents control logic conflicts; and monitoring the pressure adjustment trigger frequency identifies system anomalies in advance, reducing unplanned downtime. Attached Figure Description

[0018] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 This is a schematic diagram of the anti-cavitation system for water pumps in this invention; Figure 2 This is the control logic diagram of the water pump anti-cavitation control method in this invention; The following are the markings on the attached diagrams in the instruction manual: 1. Water tank; 2. Gas cylinder; 3. Pressure reducing valve; 4. One-way gas valve; 5. Safety valve; 6. Second solenoid valve; 7. Pressure gauge; 8. First solenoid valve; 9. Level gauge; 10. Pressure sensor; 11. Water pump. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention. Example 1

[0020] like Figure 1 As shown, the present invention provides a water pump anti-cavitation system, comprising: Expansion tank 1 is used to store circulating water and provide a pressure stabilizing space; An inert gas storage device for storing compressed inert gas; the inert gas storage device includes a gas cylinder 2 for storing compressed inert gas and a pressure reducing device 3 disposed between the gas cylinder 2 and the expansion tank 1. A pressure regulating device is used to regulate the gas pressure in the expansion tank; the pressure regulating device includes a first solenoid valve 8 and a second solenoid valve 6, the first solenoid valve 8 is disposed on the pressure relief port of the expansion tank 1; the second solenoid valve 8 is disposed on the gas line between the inert gas storage device and the expansion tank 1. Pressure detection device 10 is used to detect the system pressure at the inlet side of water pump 11; The controller, electrically connected to the pressure detection device 10 and the pressure regulating device, is used to control the operation of the pressure regulating device based on the feedback from the pressure detection device 10, so as to maintain the pressure at the inlet side of the water pump 11 above the cavitation critical pressure. The controller is configured to: control the pressure regulating device to fill the expansion tank 1 with inert gas when the pressure detection value is lower than a first set threshold; control the pressure regulating device to release the pressure in the expansion tank 1 when the pressure detection value is higher than a second set threshold; and issue an alarm signal when the operation frequency of the pressure regulating device exceeds a preset number of times within a set time.

[0021] The expansion tank 1 is equipped with a pressurization port and a water system port. The pressurization port is connected to an inert gas storage device, and the water system port is connected to the inlet pipe of the water pump 11. These ports physically separate the inert gas pressurization path from the system water circulation path. The pressurization port, located in the gas phase space at the top of the expansion tank 1, can directly apply pressure to the liquid surface. The water system port, connected to the inlet of the water pump 11, ensures a short pressure transmission path and rapid response. This structural design fully utilizes the existing expansion tank volume, eliminating the need for an additional pressure vessel and simplifying the system layout.

[0022] It also includes a level gauge 9 for monitoring the liquid level in the expansion tank 1. Setting up a level gauge to monitor the liquid level in the expansion tank 1 serves two purposes: firstly, it enables low-level alarms and automatic water replenishment control, maintaining the water volume required for normal system operation; secondly, during the water replenishment phase, the level change signal triggers the controller's shielding logic, preventing pressure fluctuations caused by rising liquid levels from erroneously triggering the air-filling action, thus preventing interference between the air-filling and water-filling processes and improving control accuracy.

[0023] The pressure reducing device 3 is a pressure reducing valve. Using a pressure reducing valve as the pressure reducing device allows the high-pressure inert gas in cylinder 2 to be stably reduced to a suitable range, providing a constant and safe inlet pressure for the lower expansion tank 1. The pressure detection device 10 is a pressure sensor arranged at the suction inlet of the water pump 11. By placing the pressure sensor at the suction inlet of the water pump 11, the pressure status at the location most prone to cavitation is directly monitored. Since the detection point coincides with the protection target, the control response is the most timely and accurate.

[0024] It also includes a one-way gas valve 4, which is installed in the gas line between the inert gas storage device and the expansion tank 1. The one-way gas valve 4 restricts the one-way flow of gas, preventing gas or liquid in the tank from flowing back to the inert gas storage device in case of system abnormality, protecting upstream equipment from contamination or damage, and maintaining the pressure stability in the expansion tank 1 to avoid pressure drop after depressurization.

[0025] It also includes a safety valve 5, which is installed on the expansion tank 1. The safety valve 5 installed on the expansion tank 1 serves as a redundant protection measure for the controller. When the controller fails, the solenoid valve malfunctions, or the pressure sensor malfunctions, causing the pressure inside the expansion tank 1 to exceed the safety limit, the safety valve 5 automatically opens to release the pressure, preventing the system from being damaged by overpressure. This constitutes a dual mechanical and electronic protection system, improving system safety.

[0026] In this embodiment, the first set threshold is determined based on the required net positive suction head (NPSH) of the water pump 11 and the saturated vapor pressure of the medium; the second set threshold is determined based on the system's pressure-bearing capacity. The first set threshold, scientifically determined based on the required NPSH of the water pump 11 and the saturated vapor pressure of the medium, ensures that the pressure before the pump is always higher than the critical cavitation value under any operating condition. The second set threshold, determined based on the system's pressure-bearing capacity, prevents excessive pressure from damaging pipelines or equipment. This dual-threshold design achieves a balance between cavitation prevention and system safety, and can be flexibly adjusted according to different pump models and medium characteristics, exhibiting strong compatibility. Example 2

[0027] This invention provides a method for preventing cavitation in water pumps, comprising the following steps: Detect the pressure at the inlet side of water pump 11; When the pressure is lower than the pressure required to prevent cavitation, inert gas is injected into the expansion tank 1, which is in fluid communication with the inlet side of the water pump 11, to increase the pressure at the inlet side of the water pump 11; when the pressure exceeds the safety limit, the gas pressure in the expansion tank 1 is released. During the stage of replenishing water to expansion tank 1, the inflation action of expansion tank 1 is blocked; Monitor the trigger frequency of dynamic voltage regulation. If the frequency exceeds a preset number of times within a set time, the system is deemed to be abnormal.

[0028] The inert gas filling rate or filling pressure is dynamically adjusted based on the pressure detection results at the inlet of water pump 11.

[0029] Specifically, such as Figure 2 As shown, the steps for dynamically adjusting the inlet pressure of the water pump 11 by receiving pressure sensor signals through the controller and controlling the opening and closing of the second solenoid valve 6 and the first solenoid valve 8 are as follows: Step 1: System Parameter Initialization: The controller first initializes the system parameters, including: Obtain the required net positive suction head (NPSHr) for this type of water pump 11; determine the saturated vapor pressure (Hvp) corresponding to the highest medium temperature during normal operation by referring to the table.

[0030] Based on the above parameters, three pressure thresholds are calculated and set: P1 (Minimum pressure threshold): P1 = HPSHr + 0.1 bar + Hvp. This value is the critical pressure that triggers the boost control. When the inlet pressure of water pump 11 is lower than this value, there is a risk of cavitation.

[0031] P2 (target pressure value): P2 = P1 + 0.5 bar. This value is the target pressure after pressurization, ensuring that the inlet pressure of water pump 11 has sufficient safety margin.

[0032] P3 (Maximum Pressure Threshold): Determined based on the rated pressure of the weakest pressure-bearing component in the system. If this component is located on the outlet side of pump 11, the setting value of P3 should be reduced accordingly based on the head of pump 11 and the pipe section resistance to prevent system overpressure damage.

[0033] Step 2: Real-time pressure monitoring: The current system pressure P0 is collected in real time by a pressure sensor placed at the suction inlet of water pump 11 at a preset sampling frequency (e.g., once per second), and the data is transmitted to the controller.

[0034] Step 3, Pressure Status Determination: The controller compares the real-time pressure P0 with the set threshold and executes the following judgment logic: Judgment condition: Is the condition P1≤P0≤P2 true for 30 seconds?

[0035] If it holds: It indicates that the current pressure is within the ideal range, and the system does not need to be adjusted. Return to step two to continue monitoring.

[0036] If it does not hold: It indicates that the pressure deviates from the ideal range, and pressure adjustment needs to be initiated. Enter step four.

[0037] It should be noted that the 30 - second delay judgment is used to filter out instantaneous pressure fluctuations, avoid frequent opening and closing of the solenoid valve due to system pressure pulsation, and improve the system stability and the service life of the valve.

[0038] Step four: Judgment of pressure deviation direction: When the pressure deviates from the ideal range, the controller further judges the deviation direction: Judgment condition: Whether P0 > P2 holds.

[0039] If it holds: It indicates that the pressure is too high, exceeding the target pressure value, and there is an overpressure risk. Enter step five to execute the pressure relief control process.

[0040] If it does not hold: It indicates that the pressure is too low or between P1 and P2 but does not meet the 30 - second condition, and there is a cavitation risk. Enter step six to execute the pressure boosting control process.

[0041] Step five: Pressure relief control process: When P0 > P2, the controller executes pressure relief control: S5 - 1: The controller issues an instruction to open the first solenoid valve 8. The gas in the expansion tank 1 is discharged through the pressure relief pipeline, the pressure in the expansion tank 1 decreases, and thus the pressure P0 on the inlet side of the water pump 11 decreases.

[0042] S5 - 2: With the first solenoid valve 8 open, the controller continuously monitors P0 and judges whether P0 > P2 holds: If it holds: It indicates that the pressure has not dropped to the target range. Keep the first solenoid valve 8 open, continue to relieve pressure, and return to S5 - 2.

[0043] If it does not hold: It indicates that the pressure has dropped below P2. Close the first solenoid valve 8, stop relieving pressure, and enter S5 - 3.

[0044] S5 - 3: Safety confirmation After closing the first solenoid valve 8, the controller judges whether P1 < P0 holds: If it holds: It indicates that the pressure is within the safe range between P1 and P2. Enter step seven for abnormal monitoring.

[0045] If it does not hold: It indicates that the pressure relief is excessive or the pressure is abnormal. Enter step six to execute the pressure boosting control process.

[0046] Step six: Pressure boosting control process: When P0 ≤ P2, the controller executes pressure boosting control: [[ID=4,5]]S6 - 1: Open the second solenoid valve 6 The controller issues an instruction to slowly open the second solenoid valve 6. The high-pressure inert gas (nitrogen in this embodiment) stored in the gas cylinder 2 is reduced to 0.5 MPa by the pressure reducing valve 3, and then passes through the one-way gas valve 4 and is injected into the top of the expansion tank 1 through the solenoid valve 1 and the pressurization interface, increasing the pressure in the gas phase space of the tank, and further increasing the pressure P0 on the inlet side of the water pump.

[0047] In this embodiment, the opening degree of the solenoid valve 1 can be dynamically adjusted according to the pressure difference between P0 and P1. When the pressure difference is large, the opening degree is increased to improve the filling rate; when the pressure difference is small, the opening degree is reduced to achieve fine adjustment and avoid overshoot of pressure.

[0048] S6-2: Real-time monitoring and closed-loop control When the solenoid valve 1 is in the open state, the controller continuously monitors P0 and judges whether P1 < P0 holds: If it does not hold: It indicates that the pressure has not yet risen to the safe range. Keep the solenoid valve 1 open, continue to pressurize, and return to S6-2.

[0049] If it holds: It indicates that the pressure has escaped from the cavitation risk area. Close the second solenoid valve 8, stop pressurizing, and enter S6-3.

[0050] S6-3: Confirmation of target achievement After closing the second solenoid valve 8, the controller judges whether P0 > P2 holds: If it does not hold: It indicates that the pressure is in the safe interval between P1 and P2, and enter step seven for abnormal monitoring.

[0051] If it holds: It indicates that the pressure has exceeded the target value and the pressurization is excessive. Return to step five for the pressure relief control process.

[0052] Interlock protection: The second solenoid valve 8 and the first solenoid valve 6 adopt an interlock control logic, and only one of them is allowed to be in the open state at the same time to prevent control conflicts and gas waste caused by simultaneous inflation and pressure relief.

[0053] Step seven, abnormal monitoring and alarm: Each time a complete pressure regulation cycle (whether it is a pressurization or pressure relief process) is completed, the controller performs the following abnormal monitoring: S7-1: Cycle counting The counter inside the controller records the number of times n that the solenoid valve is triggered to open in the last 1 hour (including the opening times of the second solenoid valve 8 and the first solenoid valve 6).

[0054] S7-2: Frequency judgment Judge whether n < 3 holds: If it holds: It indicates that the dynamic pressure regulation trigger frequency is normal, and the system is in a stable operation state. Return to step two to continue monitoring.

[0055] If this condition is not met: it indicates that the system has been triggered 3 times or more within 1 hour, resulting in excessively frequent dynamic pressure regulation. This suggests an anomaly in the system, potentially due to pipeline leaks, valve malfunctions, or insufficient system pressure capacity. The controller will issue an alarm signal to prompt maintenance personnel for repair. Simultaneously, the system can switch to manual control mode or automatic shutdown protection mode, awaiting manual intervention.

[0056] Special operating condition handling: During system operation, when the replenishment of water to expansion tank 1 is detected (identified by the signal from level gauge 9 or the flow signal from the water replenishment pipeline), the controller automatically disables the pressurization control action in step six (i.e., disables S6-1 to S6-3). This design avoids pressure fluctuations caused by the rise in tank level during water replenishment that could erroneously trigger pressurization control, and prevents interference between the air replenishment and water replenishment processes.

[0057] In addition, during the initialization phase of step one, the opening pressure of safety valve 5 is set (e.g., 0.8 MPa). When the controller or solenoid valve fails, causing an abnormal increase in pressure, the safety valve automatically opens to release pressure, serving as a mechanical redundancy protection to ensure system safety.

[0058] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A water pump anti-cavitation system, characterized in that, include: Expansion tanks are used to store circulating water and provide pressure stabilization space. Inert gas storage device for storing compressed inert gas; The inert gas storage device includes a gas cylinder for storing compressed inert gas and a pressure reducing device disposed between the gas cylinder and the expansion tank. A pressure regulating device is used to regulate the gas pressure in the expansion tank; the pressure regulating device includes a first solenoid valve and a second solenoid valve, the first solenoid valve is disposed on the pressure relief port of the expansion tank, and the second solenoid valve is disposed on the gas line between the inert gas source and the expansion tank. A pressure detection device is used to detect the system pressure at the inlet side of the water pump; The controller, electrically connected to the pressure detection device and the pressure regulating device, is used to control the operation of the pressure regulating device based on feedback from the pressure detection device to maintain the pressure at the pump inlet side above the cavitation critical pressure. The controller is configured to: control the pressure regulating device to inject inert gas into the expansion tank when the pressure detection value is lower than a first set threshold; control the pressure regulating device to release the pressure in the expansion tank when the pressure detection value is higher than a second set threshold; and issue an alarm signal when the operation frequency of the pressure regulating device exceeds a preset number of times within a set time.

2. The system according to claim 1, characterized in that, The expansion tank is equipped with a pressurization port and a water system port; the pressurization port is connected to an inert gas source; and the water system port is connected to the inlet pipe of the water pump.

3. The system according to claim 1, characterized in that: It also includes a level gauge for monitoring the liquid level in the expansion tank.

4. The system according to claim 1, characterized in that, The pressure reducing device is a pressure reducing valve.

5. The system according to claim 1, characterized in that, The pressure detection device is a pressure sensor located at the inlet of the water pump.

6. The system according to claim 1, characterized in that, It also includes a one-way gas valve, which is installed in the gas line between the inert gas source and the expansion tank.

7. The system according to claim 1, characterized in that, It also includes a safety valve, which is installed on the expansion tank.

8. The system according to claim 1, characterized in that, The first set threshold is determined based on the required net positive suction head (NPSH) of the water pump and the saturated vapor pressure of the medium; the second set threshold is determined based on the system's pressure-bearing capacity.

9. A method for preventing cavitation in water pumps, characterized in that, Includes the following steps: Detect the pressure at the inlet side of the water pump; When the pressure is lower than the pressure required to prevent cavitation, inert gas is injected into the expansion tank that is in fluid communication with the pump inlet side to increase the pressure on the pump inlet side; when the pressure exceeds the safety limit, the gas pressure in the expansion tank is released. During the stage of replenishing water to the expansion tank, the inflation action of the expansion tank is blocked. Monitor the trigger frequency of dynamic voltage regulation. If the frequency exceeds a preset number of times within a set time, the system is deemed to be abnormal.

10. The method according to claim 9, characterized in that, The inert gas filling rate or filling pressure is dynamically adjusted based on the pressure detection results at the water pump inlet.

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