Cavitation-controllable transmission system of cryogenic liquid pump

Abstract

The invention relates to the technical field of low-temperature liquid transmission, in particular to a low-temperature liquid pump cavitation controllable transmission system which comprises a low-temperature liquid source, a low-temperature liquid pump connected with a low-temperature liquid source pipeline and used for conveying low-temperature liquid, and a refrigerating system for cooling low-temperature fluid flowing from the low-temperature liquid source to the low-temperature liquid pump. The control system is connected with the refrigerating system and can receive pressure and temperature feedback signals of the low-temperature fluid in real time and dynamically adjust the supply amount or the temperature area of cold energy of the refrigerating system according to the feedback signals, so that cavitation is eliminated or relieved; through the arrangement of the cooling system and the control system, the control system can accurately adjust cold energy output of the refrigerating system based on real-time pressure and temperature feedback, it is ensured that low-temperature fluid is always in a safe interval at a pump inlet, and therefore the cavitation phenomenon of the low-temperature liquid pump is eliminated or relieved, and long-term stable operation of a conveying system is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of cryogenic transmission systems, and in particular to a cryogenic liquid pump cavitation-controllable transmission system. Background Art

[0002] In many industrial and scientific research fields, the transmission of cryogenic liquids is a key technical link, and cryogenic liquid pumps play a core role in it. For example, in the storage and transportation of liquefied natural gas (LNG), the application of liquid hydrogen and other scenarios, cryogenic liquids need to be efficiently and safely transported from storage containers to designated locations.

[0003] However, cavitation has long been a serious challenge for cryogenic liquid pumps. When cryogenic liquid flows in the pump, bubbles are formed due to the local pressure drop below the saturated vapor pressure of the liquid. These bubbles quickly collapse in the high-pressure area, generating strong shock and vibration, which not only reduces the efficiency of the pump, but also may cause serious erosion and damage to the internal structure of the pump, greatly affecting the stability and reliability of the cryogenic liquid transmission system. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a cryogenic liquid pump cavitation-controllable transmission system, aiming to solve the problem that the cavitation of cryogenic liquid in the prior art not only reduces the efficiency of the pump, but also may cause serious erosion and damage to the internal structure of the pump, greatly affecting the stability and reliability of the cryogenic liquid transmission system.

[0005] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a cavitation-controllable transmission system of a cryogenic liquid pump, characterized in that it includes a cryogenic liquid source, a cryogenic liquid pump connected to the cryogenic liquid source pipeline for conveying cryogenic liquid, a refrigeration system for refrigerating the cryogenic fluid flowing from the cryogenic liquid source to the cryogenic liquid pump, and a control system connected to the refrigeration system. The control system can receive pressure and temperature feedback signals of the cryogenic fluid in real time, and dynamically adjust the supply of cold energy or the temperature zone of the refrigeration system according to the feedback signals to eliminate or reduce cavitation.

[0006] Furthermore, the control system is connected to the cryogenic liquid pump, and the control system can receive the cavitation state of the cryogenic liquid pump in real time, and dynamically control the fluid delivery flow of the cryogenic fluid pump according to the cavitation state of the cryogenic liquid pump.

[0007] Furthermore, the control system has a built-in storage module and a control module, and the storage module stores the saturated temperature-pressure relationship data of the cryogenic liquid and the temperature-pressure diagram data when the pump does not cavitation; it also includes a plurality of sensors for obtaining the pressure parameter P of the cryogenic fluid and the actual measured temperature T1 of the cryogenic liquid; the control module can calculate the corresponding saturation temperature T2 from the obtained pressure parameter P according to the saturated temperature-pressure relationship data in the storage module, and determine the required inlet temperature T3 of the pump inlet according to the stored temperature-pressure diagram data when the pump does not cavitation; when cavitation occurs, the control module implements at least one of the following control measures according to the actual measured temperature T1 of the cryogenic liquid, the flow rate of the refrigeration system and the determined required inlet temperature T3 of the pump inlet: reducing the fluid delivery flow rate of the cryogenic fluid pump, increasing the supply of cold energy of the refrigeration system, and adjusting the temperature zone of the cold energy of the refrigeration system, thereby eliminating or reducing the cavitation of the cryogenic liquid pump.

[0008] Furthermore, it also includes a flow sensor for detecting the inlet and outlet flow rates of the cryogenic fluid pump, and the flow sensor is connected to the control system.

[0009] Furthermore, it also includes a vibration sensor installed on the cryogenic fluid pump, and the vibration sensor is connected to the control system.

[0010] Furthermore, the refrigeration system includes a compressor, a cooler, a multi-stream heat exchanger and an expander; the outlet of the compressor is connected to the inlet pipeline of the cooler, the outlet of the cooler is connected to the first inlet pipeline of the multi-stream heat exchanger, the first outlet of the multi-stream heat exchanger corresponding to the first inlet is connected to the inlet pipeline of the expander, the outlet of the expander is connected to the second inlet pipeline of the multi-stream heat exchanger, the second outlet of the multi-stream heat exchanger corresponding to the second inlet is connected to the inlet pipeline of the compressor, and the multi-stream heat exchanger also includes a third inlet and a third outlet, the third inlet is connected to the outlet pipeline of the low-temperature liquid source, and the third outlet is connected to the inlet pipeline of the low-temperature liquid pump.

[0011] Furthermore, the cryogenic liquid source is a cryogenic liquid tank storing cryogenic liquid therein.

[0012] Furthermore, the compressor is a centrifugal impeller compressor, and the expander is a centrifugal impeller expander or a cryogenic throttle valve.

[0013] Furthermore, it also includes a driving device for driving the compressor and the expander to operate. A driving device is connected to the compressor and the expander, and the driving device can drive the compressor and the expander to operate simultaneously.

[0014] Furthermore, it also includes a driving device for driving the compressor and the expander to operate. A driving device is connected to the compressor and the expander, and the driving device can drive the compressor and the expander to operate simultaneously.

[0015] The present invention describes a low-temperature liquid pump cavitation-controllable transmission system, which has the beneficial effect of: through the setting of the cooling system and the control system, the control system can accurately adjust the cold energy output of the refrigeration system based on real-time pressure and temperature feedback, ensuring that the low-temperature fluid is always in a safe temperature and pressure range at the pump inlet, thereby eliminating or reducing the cavitation phenomenon of the low-temperature liquid pump and ensuring the long-term stable operation of the transmission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart of a cryogenic liquid pump cavitation-controllable transmission system according to an embodiment of the present invention.

[0017] Explanation of the reference numerals: 1. Cryogenic liquid tank; 2. Cryogenic liquid pump; 3. Multi-stream heat exchanger; 4. Cooler; 5. Compressor; 6. Expander; 7. Driving device. DETAILED DESCRIPTION

[0018] Typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various changes in different embodiments without departing from the scope of the present invention, and the descriptions and illustrations therein are essentially used for illustration purposes rather than for limiting the present invention.

[0019] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0020] In order to further illustrate the principle and structure of the present invention, preferred embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0021] like Figure 1As shown, an embodiment of the present invention provides a transmission system with controllable cavitation of a cryogenic liquid pump 2, comprising: a cryogenic liquid source, a cryogenic liquid pump 2, a refrigeration system and a control system. The cryogenic liquid pump 2 is connected to the cryogenic liquid source through a pipeline for conveying cryogenic liquid; the refrigeration system is arranged on the pipeline between the cryogenic liquid source and the cryogenic liquid pump 2 for cooling the cryogenic fluid flowing to the cryogenic liquid pump 2; the control system is connected to the refrigeration system, receives the pressure and temperature feedback signals of the cryogenic fluid in real time, and dynamically adjusts the cold energy supply or cold energy temperature zone of the refrigeration system according to the feedback signals. When cavitation occurs, the control system can accurately adjust the cold energy output of the refrigeration system based on the real-time pressure and temperature feedback, ensuring that the cryogenic fluid is always in a safe temperature and pressure range at the pump inlet, thereby eliminating or reducing the cavitation phenomenon of the cryogenic liquid pump 2 and ensuring the long-term stable operation of the transmission system.

[0022] Furthermore, the cryogenic liquid source is a container for storing cryogenic liquid (such as liquid hydrogen, LNG, liquid oxygen, liquid nitrogen, etc.). In the embodiment of the present invention, the cryogenic liquid source is a cryogenic liquid tank 1 storing cryogenic liquid, and its outlet is connected to the inlet of the cryogenic liquid pump 2 through a cryogenic high-pressure pipeline. The cryogenic liquid is transported to the target location under the drive of the pump.

[0023] Furthermore, the control system is connected to the cryogenic liquid pump 2 , and the control system can receive the cavitation state of the cryogenic liquid pump 2 in real time according to the cavitation state of the cryogenic liquid pump 2 , and dynamically control the fluid delivery flow of the cryogenic fluid pump according to the cavitation state of the cryogenic liquid pump 2 .

[0024] Specifically, the control system can determine the cavitation state of the cryogenic liquid pump 2 by detecting the flow rate of the cryogenic liquid pump 2 in real time. Therefore, an embodiment of the present invention also includes a flow sensor for detecting the inlet and outlet flow rates of the cryogenic fluid pump. The flow sensor is connected to the control system. By installing the flow sensor on the inlet and outlet pipes of the cryogenic fluid pump, the flow rate change can be monitored. The flow anomaly caused by cavitation is often accompanied by pulsation. The control system performs real-time analysis on the flow data collected by the flow sensor to calculate the fluctuation frequency and amplitude of the flow rate. If the flow fluctuation frequency is higher than the frequency during normal operation, and the amplitude changes greatly, it can be determined that cavitation has occurred. When the control system determines that cavitation has occurred, in addition to the control system dynamically adjusting the refrigeration system as described above, the control system can also adjust the drive motor speed or outlet valve opening of the cryogenic liquid pump 2 as needed to reduce the delivery flow rate of the cryogenic fluid and reduce the fluid flow rate, thereby suppressing the formation of cavitation bubbles.

[0025] Flow regulation can work in conjunction with the refrigeration system described above. For example, while reducing the flow, the control system still adjusts the cooling energy output of the refrigeration system based on the temperature feedback of the cryogenic fluid to ensure that the cryogenic fluid is always in a supercooled state, further eliminating the cause of cavitation.

[0026] The flow sensor may be an existing electromagnetic flowmeter, a vortex flowmeter or other sensors that can realize flow monitoring in this embodiment.

[0027] Furthermore, the control system can also determine the cavitation state of the cryogenic liquid pump 2 by detecting the vibration of the cryogenic liquid pump 2 in real time. An embodiment of the present invention also includes a vibration sensor installed on the cryogenic fluid pump, and the vibration sensor is connected to the control system. When the cryogenic fluid pump is operating normally, its vibration amplitude is in a specific stable range. The control system will pre-set the threshold value of the vibration amplitude under normal operating conditions. Based on the piezoelectric effect or the capacitive effect, when the pump body vibrates due to cavitation, the vibration sensor will sense the amplitude of the vibration and convert it into an electrical signal output. The control system processes the electrical signal output by the vibration sensor. When the vibration amplitude detected by the vibration sensor exceeds this threshold, it can be determined that cavitation has occurred. The vibration sensor can be an existing piezoelectric accelerometer, a capacitive accelerometer or other sensor that can realize vibration monitoring of this embodiment.

[0028] In addition to the flow sensor and vibration sensor for detecting the cavitation state of the cryogenic liquid pump 2, the embodiment of the present invention also includes multiple sensors for obtaining the pressure parameter P of the cryogenic fluid and the actual temperature T1 of the cryogenic liquid. These sensors are all connected to the control system and can transmit the acquired data to the control system. The above sensors can all be implemented using existing sensors. This application does not improve the sensors, so they are not described in detail.

[0029] Furthermore, the control system has a built-in storage module and a control module. The storage module stores the saturated temperature-pressure relationship data of the cryogenic liquid and the temperature-pressure diagram data of the cryogenic liquid pump 2 without cavitation. The control module can calculate the corresponding saturation temperature T2 from the acquired pressure parameter P according to the saturated temperature-pressure relationship data in the storage module, and determine the inlet temperature T3 required for the inlet of the cryogenic liquid pump 2 according to the stored temperature-pressure diagram data of the cryogenic liquid pump 2 without cavitation. The actual measured temperature of the cryogenic fluid is T1. When cavitation occurs, the control system determines the operating power (speed) of the refrigeration system according to the flow rate, T3 and T1 of the cryogenic liquid pump 2, so as to provide the cold energy required to eliminate cavitation. This power (speed)-cold energy is the built-in logic of the refrigeration system. When the temperature T4 ≤ T3 provided by the refrigeration system, the cryogenic fluid pump can start to run.

[0030] If cavitation occurs in the cryogenic fluid pump according to the control logic, the fluid delivery flow rate of the cryogenic fluid pump is reduced, or the supply of cold energy of the refrigeration system is increased, or the temperature zone of the cold energy of the refrigeration system is adjusted to eliminate or reduce cavitation.

[0031] Furthermore, the above-mentioned refrigeration system is mainly composed of a compressor 5, a cooler 4, a multi-stream heat exchanger 2 and an expander 6, and each component is connected by a specific pipeline to form a complete circulation loop. The outlet of the compressor 5 is connected to the inlet of the cooler 4 through a pipeline that is resistant to high pressure, low temperature and has good sealing performance, ensuring that the compressed high-temperature refrigerant can smoothly enter the cooler 4 for cooling treatment. The outlet of the cooler 4 is connected to the first inlet of the multi-stream heat exchanger 2, so that the cooled refrigerant enters the multi-stream heat exchanger 2. The first outlet of the multi-stream heat exchanger 2 is connected to the inlet of the expander 6, ensuring that the cooled refrigerant can enter the expander 6 for expansion and cooling operations. The outlet of the expander 6 is connected to the second inlet of the multi-stream heat exchanger 2, and the refrigerant after expansion and cooling enters the multi-stream heat exchanger 2 again from here, and then flows out from the second outlet of the multi-stream heat exchanger 2 and returns to the inlet of the compressor 5, forming a circulation of the refrigerant.

[0032] Further, the compressor 5 may be a screw compressor 5 or a piston compressor 5, and the compressor 5 is preferably a centrifugal impeller compressor 5. The expander 6 is a centrifugal impeller expander 6. The centrifugal impeller compressor 5 and the centrifugal impeller expander 6 are coaxially arranged and driven by a driving device 7, and the driving device 7 may be a dual-shaft motor, which can drive the compressor 5 and the expander 6 to operate simultaneously.

[0033] When the cryogenic fluid is planned to be transmitted, the refrigeration system starts to operate first. The refrigerant compressed by the compressor 5 enters the cooler 4 for cooling, then enters the multi-stream heat exchanger 2 for cooling, and then enters the expander 6 for expansion and cooling. After that, the refrigerant enters the multi-stream heat exchanger 2 again for heat exchange with the cryogenic fluid, and then returns to the compressor 5 inlet.

[0034] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A cryogenic liquid pump cavitation controllable transmission system, characterized in that: It includes a cryogenic liquid source, a cryogenic liquid pump connected to the cryogenic liquid source pipeline for conveying cryogenic liquid, a refrigeration system for cooling the cryogenic fluid flowing from the cryogenic liquid source to the cryogenic liquid pump, and a control system connected to the refrigeration system. The control system can receive pressure and temperature feedback signals of the cryogenic fluid in real time, and dynamically adjust the supply of cold energy or the temperature zone of the refrigeration system according to the feedback signals to eliminate or reduce cavitation.

2. The cryogenic liquid pump cavitation-controlled transmission system according to claim 1, characterized in that: The control system is connected to the cryogenic liquid pump, and the control system can receive the cavitation state of the cryogenic liquid pump in real time, and dynamically control the fluid delivery flow of the cryogenic fluid pump according to the cavitation state of the cryogenic liquid pump.

3. The cryogenic liquid pump cavitation controllable transmission system according to claim 2, characterized in that: The control system has a built-in storage module and a control module, and the storage module stores the saturated temperature-pressure relationship data of the cryogenic liquid and the temperature-pressure diagram data of the pump without cavitation; it also includes a plurality of sensors for obtaining the pressure parameter P of the cryogenic fluid and the actual measured temperature T1 of the cryogenic liquid; the control module can calculate the corresponding saturation temperature T2 from the obtained pressure parameter P according to the saturated temperature-pressure relationship data in the storage module, and determine the required inlet temperature T3 of the pump inlet according to the stored temperature-pressure diagram data of the pump without cavitation; when cavitation occurs, the control module implements at least one of the following control measures according to the actual measured temperature T1 of the cryogenic liquid, the flow rate of the refrigeration system and the determined required inlet temperature T3 of the pump inlet: reducing the fluid delivery flow rate of the cryogenic fluid pump, increasing the supply of cold energy of the refrigeration system, and adjusting the temperature zone of the cold energy of the refrigeration system, thereby eliminating or reducing the cavitation of the cryogenic liquid pump.

4. The cryogenic liquid pump cavitation-controlled transmission system according to claim 3, characterized in that: It also includes a flow sensor for detecting the inlet and outlet flow rates of the cryogenic fluid pump, and the flow sensor is connected to the control system.

5. The cryogenic liquid pump cavitation-controlled transmission system according to claim 4, characterized in that: It also includes a vibration sensor installed on the cryogenic fluid pump, and the vibration sensor is connected to the control system.

6. The cryogenic liquid pump cavitation-controlled transmission system according to claim 2, characterized in that: The refrigeration system includes a compressor, a cooler, a multi-stream heat exchanger and an expander; the outlet of the compressor is connected to the inlet pipeline of the cooler, the outlet of the cooler is connected to the first inlet pipeline of the multi-stream heat exchanger, the first outlet of the multi-stream heat exchanger corresponding to the first inlet is connected to the inlet pipeline of the expander, the outlet of the expander is connected to the second inlet pipeline of the multi-stream heat exchanger, the second outlet of the multi-stream heat exchanger corresponding to the second inlet is connected to the inlet pipeline of the compressor, the multi-stream heat exchanger also includes a third inlet and a third outlet, the third inlet is connected to the outlet pipeline of the low-temperature liquid source, and the third outlet is connected to the inlet pipeline of the low-temperature liquid pump.

7. The cryogenic liquid pump cavitation-controlled transmission system according to claim 6, characterized in that: The cryogenic liquid source is a cryogenic liquid tank storing cryogenic liquid therein.

8. The cryogenic liquid pump cavitation-controlled transmission system according to claim 6, characterized in that: The compressor is a centrifugal impeller compressor, and the expander is a centrifugal impeller expander or a cryogenic throttle valve.

9. The cryogenic liquid pump cavitation-controlled transmission system according to claim 8, characterized in that: It also includes a driving device for driving the compressor and the expander to operate. A driving device is connected to the compressor and the expander, and the driving device can drive the compressor and the expander to operate simultaneously.

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