Evaporative cooling system for bearings of hydroelectric generating units

Abstract

This invention discloses an evaporative cooling system for the bearings of a hydro-generator set, relating to the field of bearing heat dissipation technology. A condenser, evaporator, and drive pump form a cooling circuit. The evaporator is arranged within the bearing's oil sump and configured to absorb heat through the evaporation of a phase change medium to cool the lubricating oil flowing through the bearing. The condenser is configured to condense the vaporized phase change medium into a liquid state. The drive pump and a first control valve form a bypass circuit, with the first control valve configured to control the flow rate of the bypass circuit. Thus, by arranging the evaporator within the bearing's oil sump and allowing the phase change medium to flow through it, the lubricating oil in the oil sump can be cooled through the evaporation of the phase change medium, reducing the risk of scaling and wear on the heat exchange tube walls. Regular shutdowns for cleaning are unnecessary, resulting in low maintenance costs and high heat exchange efficiency. Furthermore, by forming a bypass circuit with the drive pump and the first control valve, the flow rate of the phase change medium entering the evaporator can be diverted and adjusted, which helps improve the accuracy of lubricating oil temperature control.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation technology, and in particular to an evaporative cooling system for the bearings of a hydro-generator set. Background Technology

[0002] In related technologies, the thrust bearing and guide bearing of a hydro-generator unit generate a large amount of heat during operation. A cooling system is needed to control the lubricating oil temperature within an optimal range to ensure bearing lubrication performance. Existing cooling systems directly cool the lubricating oil in the oil sump using water cooling, leading to gradual scaling and wear on the heat exchange tube walls. This requires regular cleaning, results in low heat exchange efficiency, high maintenance costs, and difficulty in accurately controlling the lubricating oil temperature. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one object of the present invention is to provide an evaporative cooling system for the bearings of a hydro-generator set, which has high heat exchange efficiency, low maintenance cost, precise control of lubricating oil temperature, and convenient operation.

[0004] The evaporative cooling system for the bearing of a hydro-generator set according to the present invention includes: an evaporator, a condenser, and a drive pump, wherein the condenser, the evaporator, and the drive pump form a cooling circuit, the evaporator is arranged in the oil sump of the bearing, a phase change medium flows through the cooling circuit, the evaporator is configured to absorb heat through evaporation of the phase change medium to cool the lubricating oil flowing through the bearing, and the condenser is configured to condense the vaporized phase change medium into a liquid state; a first control valve, wherein the drive pump and the first control valve form a bypass circuit, and the first control valve is configured to control the flow rate of the bypass circuit.

[0005] According to the present invention, the evaporative cooling system for the bearing of a hydro-generator set, by arranging the evaporator in the oil sump of the bearing and allowing the phase change medium to flow through the evaporator, can cool the lubricating oil in the oil sump by absorbing heat through the evaporation of the phase change medium, reducing the risk of scaling and wear on the heat exchange tube wall, eliminating the need for periodic shutdown for cleaning, resulting in low maintenance costs and high heat exchange efficiency. By forming a bypass circuit between the drive pump and the first control valve, the flow rate of the phase change medium entering the evaporator can be diverted and adjusted, which is beneficial to improving the accuracy of lubricating oil temperature control.

[0006] In some examples of the present invention, the evaporative cooling system for the bearing of the hydro-generator set further includes: a liquid storage tank, which is located upstream of the drive pump and downstream of the condenser and the first control valve.

[0007] In some examples of the present invention, the evaporative cooling system of the bearing of the hydro-generator set further includes: a sight glass, which is disposed between the condenser and the drive pump, and is configured to observe the flow state and phase state of the phase change medium through the sight glass.

[0008] In some examples of the invention, the sight glass includes a color-changing indicator configured to change color in response to changes in the moisture content of the phase change medium.

[0009] In some examples of the present invention, the condenser has a first flow channel and a second flow channel, the first flow channel, the evaporator, and the drive pump forming the cooling circuit, and the second flow channel is configured to allow river water to flow through it.

[0010] In some examples of the present invention, the evaporative cooling system for the bearing of the hydro-generator set further includes: a first temperature sensor and a controller. The first temperature sensor is disposed in the oil tank and configured to detect the temperature in the oil tank. The controller is connected to both the first temperature sensor and the drive pump and is configured to adjust the speed of the drive pump according to the information fed back by the first temperature sensor.

[0011] In some examples of the present invention, the evaporative cooling system for the bearing of the hydro-generator set further includes: a main shaft speed sensor and a controller, wherein the main shaft speed sensor is connected to the controller, the main shaft speed sensor is configured to detect the speed of the main shaft, and the controller is configured to adjust the speed of the drive pump based on the information fed back by the main shaft speed sensor.

[0012] In some examples of the present invention, the evaporative cooling system for the bearing of the hydro-generator set further includes: a second temperature sensor, a first pressure sensor, and a controller. The second temperature sensor and the first pressure sensor are located between the evaporator and the condenser and are configured to detect the temperature and pressure of the phase change medium at the outlet of the evaporator. The controller is connected to both the second temperature sensor and the first pressure sensor and is configured to calculate the superheat of the phase change medium based on the information fed back by the second temperature sensor and the first pressure sensor, and control the opening degree of the first control valve based on the superheat.

[0013] In some examples of the present invention, the evaporative cooling system of the bearing of the hydro-generator set further includes: a third temperature sensor, a second pressure sensor, a second control valve, and a controller. The third temperature sensor and the second pressure sensor are both located between the condenser and the drive pump, and are respectively configured to detect the temperature and pressure of the phase change medium at the outlet of the condenser. The second control valve is located in the condenser. The second control valve is connected to the controller and configured to control the flow rate of the cooling water in the condenser. The controller is connected to both the third temperature sensor and the second pressure sensor and is configured to calculate the subcooling of the phase change medium based on the information fed back by the third temperature sensor and the second pressure sensor, and control the opening degree of the second control valve based on the subcooling.

[0014] In some examples of the present invention, the evaporative cooling system for the bearing of the hydro-generator set further includes: a controller, which is connected to both the first control valve and the drive pump and is configured to synchronously adjust the speed of the drive pump according to the expected change in the opening of the first control valve when it is necessary to control the opening of the first control valve.

[0015] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the evaporative cooling system according to an embodiment of the present invention.

[0017] Figure label: Evaporative cooling system 100; Cooling circuit 99; Bypass circuit 98; Evaporator 10; Condenser 20; Drive pump 30; First control valve 40; Liquid storage tank 50; Sight glass 60; Oil tank 70; First temperature sensor 81; Second temperature sensor 82; Third temperature sensor 83; First pressure sensor 91; second pressure sensor 92. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0019] The following is for reference. Figure 1 An evaporative cooling system 100 for the bearings of a hydro-generator set according to an embodiment of the present invention is described.

[0020] like Figure 1As shown, the evaporative cooling system 100 of the bearing of the hydro-generator set according to an embodiment of the present invention includes: an evaporator 10, a condenser 20, a drive pump 30, and a first control valve 40.

[0021] The condenser 20, evaporator 10, and drive pump 30 form a cooling circuit 99. The evaporator 10 is arranged in the oil sump 70 of the bearing. A phase change medium flows inside the cooling circuit 99. The evaporator 10 is configured to absorb heat through the evaporation of the phase change medium to cool the lubricating oil flowing through the bearing. The condenser 20 is configured to condense the vaporized phase change medium into a liquid state. The drive pump 30 and the first control valve 40 form a bypass circuit 98. The first control valve 40 is configured to control the flow rate of the bypass circuit 98.

[0022] In this embodiment, the condenser 20, evaporator 10, and drive pump 30 form a cooling circuit 99. As some embodiments of this application, the condenser 20, evaporator 10, and drive pump 30 are connected by pipelines to form the cooling circuit 99, and a phase change medium can flow in the cooling circuit 99. The phase change medium can be, but is not limited to, R-113 (Freon), novel environmentally friendly fluorocarbon compounds, etc. As some embodiments of this application, the evaporator 10 is constructed as a fixed coil structure and is arranged within the oil sump 70 of the bearing; the evaporator 10 does not rotate with the bearing spindle. As some embodiments of this application, the inlet and outlet pipelines of the evaporator 10 are fixed to the side wall of the oil sump 70 by vibration-damping pipe clamps, and corrugated compensation sections are provided at the bends in the pipelines.

[0023] Evaporator 10 is arranged within the oil sump 70 of the bearing. As in some embodiments of this application, evaporator 10 has heat exchange pipes, at least a portion of which is immersed in lubricating oil to exchange heat with the lubricating oil in the oil sump 70. When the phase change medium flows through evaporator 10, it can absorb heat from the lubricating oil and cool the lubricating oil flowing through the bearing by evaporating and absorbing heat.

[0024] Next, the vaporized phase change medium flows through the condenser 20, which can condense the vaporized phase change medium into a liquid state. The drive pump 30 can drive the liquid phase change medium to circulate in the cooling circuit 99.

[0025] The drive pump 30 and the first control valve 40 form a bypass circuit 98. In some embodiments of this application, the bypass circuit 98 is connected in parallel with the drive pump 30. The first control valve 40 is located in the bypass circuit 98 and can control the flow rate of the bypass circuit 98. In some embodiments of this application, the flow rate of the bypass circuit 98 is increased by increasing the opening degree of the first control valve 40. In some embodiments of this application, the flow rate of the bypass circuit 98 is decreased by decreasing the opening degree of the first control valve 40.

[0026] It should be noted that the evaporative cooling system 100 of the bearing of the hydro-generator set of this application, by arranging the evaporator 10 in the oil groove 70 of the bearing and allowing the phase change medium to flow through the evaporator 10, can utilize the evaporation and vaporization of the phase change medium to absorb the heat of the lubricating oil, thereby achieving phase change heat transfer. The heat transfer coefficient is higher than that of the traditional water cooling scheme, avoiding the problems of impurity deposition, scaling and wear of the traditional water cooling scheme. It does not require regular shutdown for cleaning and has low maintenance costs.

[0027] Moreover, the bypass circuit 98 can provide the evaporative cooling system 100 with a flow regulation dimension independent of the speed regulation of the drive pump 30, and can regulate the liquid supply of the evaporator 10 without changing the operating state of the drive pump 30, which is beneficial to improving the flexibility of system control.

[0028] Furthermore, the evaporator 10, condenser 20, drive pump 30 and bypass circuit 98 of this application constitute a complete closed cooling cycle, which has a simple structure, few parts, low engineering implementation difficulty, and is easy to debug and maintain on site.

[0029] Therefore, by arranging the evaporator 10 within the oil sump 70 of the bearing and allowing the phase change medium to flow through the evaporator 10, the phase change medium can absorb heat through evaporation to cool the lubricating oil in the oil sump 70, reducing the risk of scaling and wear on the heat exchange tube walls. This eliminates the need for periodic shutdowns for cleaning, resulting in low maintenance costs and high heat exchange efficiency. Furthermore, by forming a bypass circuit 98 between the drive pump 30 and the first control valve 40, the flow rate of the phase change medium entering the evaporator 10 can be diverted and regulated, which helps improve the accuracy of lubricating oil temperature control.

[0030] In some embodiments of the present invention, such as Figure 1 As shown, the evaporative cooling system 100 of the bearing of the hydro-generator set also includes: a liquid storage tank 50, which is located upstream of the drive pump 30, downstream of the condenser 20 and downstream of the first control valve 40.

[0031] In other words, as some embodiments of this application, in the cooling circuit 99, the liquid storage tank 50 is located between the drive pump 30 and the condenser 20. As some embodiments of this application, in the bypass circuit 98, the liquid storage tank 50 is located between the first control valve 40 and the condenser 20, and the phase change medium passing through the first control valve 40 enters the liquid storage tank 50 under the action of the drive. The liquid storage tank 50 can be used to store liquid phase change media.

[0032] This configuration provides a low-pressure return interface for the bypass circuit 98 via the liquid storage tank 50, allowing the diverted phase change medium to flow smoothly back to the upstream of the drive pump 30. Furthermore, the liquid storage tank 50 stores the phase change medium required for the evaporative cooling system 100's circulation, acting as a buffer and dynamically regulating agent to ensure a constant supply of liquid phase change medium to the drive pump 30. Simultaneously, the liquid storage tank 50 enables gas-liquid separation, reducing the risk of incompletely condensed gaseous phase change medium entering the drive pump 30, effectively lowering the risk of cavitation in the drive pump 30, and improving the system's operational reliability.

[0033] In some embodiments of the present invention, such as Figure 1 As shown, the evaporative cooling system 100 of the bearing of the hydro-generator set also includes a sight glass 60, which is located between the condenser 20 and the drive pump 30. The sight glass 60 is configured to observe the flow state and phase state of the phase change medium through the sight glass 60.

[0034] The sight glass 60 is located between the condenser 20 and the drive pump 30. In some embodiments of this application, in the cooling circuit 99, the sight glass 60 is located upstream of the storage tank 50 and downstream of the condenser 20. The sight glass 60 allows the operator to observe the flow state and phase of the phase change medium.

[0035] As some embodiments of this application, the sight glass 60 is constructed as a pressure-resistant sight glass 60, and the nominal pressure is not less than 1.5 times the system design pressure.

[0036] It should be noted that, under normal circumstances, the sight glass 60 should show a transparent liquid phase change medium filled with no bubbles. If intermittent bubbles are observed, it indicates that the phase change medium charge of the evaporative cooling system 100 is insufficient or the condensation pressure is too low. It is necessary to add phase change medium or check the cooling water flow rate of the condenser 20. If continuous bubbles (flash) are observed, it indicates that there is a risk of cavitation at the inlet of the drive pump 30. The cooling water flow rate should be increased immediately. If there is no liquid flow, it indicates that the phase change medium is seriously leaking or the drive pump 30 is malfunctioning. It is necessary to shut down the system immediately for inspection.

[0037] By including a sight glass 60 in the evaporative cooling system 100, on-site maintenance personnel can quickly make a preliminary judgment on the status of the evaporative cooling system 100, so as to quickly troubleshoot the evaporative cooling system 100 during maintenance.

[0038] In some embodiments of the present invention, the sight glass 60 includes a color-changing indicator configured to change color in response to changes in the moisture content of the phase change medium.

[0039] In other words, the color-changing indicator can change color according to the change in moisture content of the phase change medium. By including the color-changing indicator in the sight glass 60, the moisture content of the phase change medium can be understood by observing the sight glass 60, which helps to improve maintenance efficiency.

[0040] In some embodiments of the present invention, the condenser 20 has a first flow channel and a second flow channel, the first flow channel, the evaporator 10, and the drive pump 30 forming a cooling circuit 99, and the second flow channel is configured to allow river water to flow through it.

[0041] The condenser 20 has a first flow channel and a second flow channel. The first flow channel, the evaporator 10, and the drive pump 30 are connected by a pipeline to form a cooling circuit 99. The second flow channel is for river water to flow through. That is to say, when the vaporized phase change medium enters the first flow channel, it will exchange heat with the river water in the second flow channel so that the heat of the phase change medium can be carried away by the river water and liquefy it.

[0042] This setup utilizes the abundant cooling water resources of the hydropower station to cool the phase change medium, resulting in low cost, high resource utilization, and good cooling effect. It can reduce the risk of lubricating oil emulsification caused by cooling water leakage. At the same time, the second flow channel can be cleaned regularly according to the scaling situation, making operation simple and convenient for later maintenance.

[0043] In some embodiments of the present invention, such as Figure 1 As shown, the evaporative cooling system 100 of the bearing of the hydro-generator set also includes: a first temperature sensor 81 and a controller (not shown in the figure). The first temperature sensor 81 is located in the oil tank 70 and is configured to detect the temperature in the oil tank 70. The controller is connected to the first temperature sensor 81 and the drive pump 30 and is configured to adjust the speed of the drive pump 30 according to the information fed back by the first temperature sensor 81.

[0044] The first temperature sensor 81 is connected to the controller. In some embodiments of this application, the first temperature sensor 81 and the controller are connected via a wire. The drive pump 30 is also connected to the controller. In some embodiments of this application, the drive pump 30 and the controller are connected via a wire. The first temperature sensor 81 is located inside the oil tank 70 and can detect the temperature inside the oil tank 70. The controller can adjust the rotational speed of the drive pump 30 based on the temperature information fed back by the first temperature sensor 81.

[0045] As some embodiments of this application, the drive pump 30 employs a PID (proportional-integral-derivative) control algorithm, with feedback from the first temperature sensor 81 as the main input.

[0046] This configuration allows for increased speed of the drive pump 30 when the oil temperature rises to increase the circulation flow of the phase change medium and enhance heat exchange. Conversely, it reduces the speed of the drive pump 30 when the oil temperature drops to decrease the circulation flow, thus preventing excessive cooling of the oil and saving energy. This ensures that the temperature of the oil sump 70 is precisely controlled within the target range, guaranteeing stable bearing lubrication performance.

[0047] This setting enables automatic and precise adjustment of oil temperature, with high control accuracy and fast response speed. It requires no manual intervention, which reduces the risk of the drive pump 30 operating under excessively high or low loads for a long time. This helps to reduce the energy consumption of the drive pump 30 and extend its service life.

[0048] In some embodiments of the present invention, the evaporative cooling system 100 of the bearing of the hydro-generator set further includes: a main shaft speed sensor (not shown in the figure) and a controller (not shown in the figure). The main shaft speed sensor is connected to the controller. The main shaft speed sensor is configured to detect the speed of the main shaft. The controller is configured to adjust the speed of the drive pump 30 according to the information fed back by the main shaft speed sensor.

[0049] In this embodiment, the spindle speed sensor is connected to the controller. As part of some embodiments of this application, the spindle speed sensor and the controller are connected via a wire. The spindle speed sensor can detect the spindle speed, and the controller can adjust the speed of the drive pump 30 based on the speed information fed back by the spindle speed sensor.

[0050] As some embodiments of this application, the main shaft speed sensor is installed in the turbine unit and can detect the speed of the turbine unit's main shaft. The controller can receive the information fed back by the main shaft speed sensor as a feedforward input. If the speed of the turbine unit's main shaft is detected to increase, the controller synchronously increases the speed of the drive pump 30. If the speed of the turbine unit's main shaft is detected to decrease, the controller synchronously decreases the speed of the drive pump 30.

[0051] It is understandable that the main shaft speed directly reflects the operating status and heat load change trend of the hydro-generator unit. When the main shaft speed increases, the frictional power consumption of the main shaft increases and the heat generation of the lubricating oil increases. The controller can increase the speed of the drive pump 30 in advance to increase the circulation flow of the phase change medium and enhance cooling. When the main shaft speed decreases, the heat load decreases, and the controller correspondingly reduces the speed of the drive pump 30 to reduce excessive cooling and energy waste.

[0052] This setting allows for pre-adjustment of the drive pump 30 before the actual change in oil temperature, effectively suppressing oil temperature fluctuations, reducing the risk of significant overshoot caused by oil temperature hysteresis response, making oil temperature control more stable, and improving the dynamic response capability of the evaporative cooling system 100.

[0053] In some embodiments of the present invention, such as Figure 1As shown, the evaporative cooling system 100 of the bearing of the hydro-generator set further includes: a second temperature sensor 82, a first pressure sensor 91, and a controller. The second temperature sensor 82 and the first pressure sensor 91 are located between the evaporator 10 and the condenser 20, and are configured to detect the temperature and pressure of the phase change medium at the outlet of the evaporator 10. The controller is connected to both the second temperature sensor 82 and the first pressure sensor 91 and is configured to calculate the superheat of the phase change medium based on the information fed back by the second temperature sensor 82 and the first pressure sensor 91, and control the opening degree of the first control valve 40 based on the superheat.

[0054] The controller is connected to both the second temperature sensor 82 and the first pressure sensor 91. In some embodiments of this application, the controller is connected to both the second temperature sensor 82 and the first pressure sensor 91 via wires.

[0055] The second temperature sensor 82 and the first pressure sensor 91 are both located between the evaporator 10 and the condenser 20. The second temperature sensor 82 can detect the temperature of the phase change medium at the outlet of the evaporator 10, and the first pressure sensor 91 can detect the pressure of the phase change medium at the outlet of the evaporator 10.

[0056] The controller can calculate the superheat of the phase change medium based on the information fed back by the second temperature sensor 82 and the first pressure sensor 91, and control the opening degree of the first control valve 40 based on the superheat of the phase change medium.

[0057] It is understandable that superheat is the difference between the actual temperature of the gaseous phase change medium and its saturation temperature (boiling point) at the current pressure.

[0058] As some embodiments of this application, the first control valve 40 adopts a PI (proportional-integral) control algorithm. Taking the superheat at the outlet of the evaporator 10 as input, the controller can calculate the superheat based on the second temperature sensor 82 at the outlet of the evaporator 10 and the first pressure sensor 91 at the outlet of the evaporator 10. When the superheat is higher than the target superheat, the controller can control the first control valve 40 to reduce the flow of the bypass circuit 98, increase the flow of the phase change medium to the evaporator 10, and improve the cooling effect. When the superheat is lower than the safety threshold, the controller can control the first control valve 40 to increase the flow of the bypass circuit 98, reduce the flow of the phase change medium to the evaporator 10, and improve the vaporization efficiency of the phase change medium.

[0059] It should be noted that the superheat can accurately indicate the degree of heat exchange in the evaporator 10. When the superheat is too low, it indicates that there is still incompletely vaporized liquid phase change medium at the outlet of the evaporator 10. The controller increases the opening of the first control valve 40 to increase the flow of the bypass circuit 98, thereby reducing the flow of the phase change medium entering the evaporator 10 and increasing the superheat. When the superheat is too high, it indicates that the flow of the phase change medium in the evaporator 10 is insufficient. The controller decreases the opening of the first control valve 40 to reduce the bypass flow, thereby increasing the flow of the phase change medium entering the evaporator 10 and decreasing the superheat, so that the heat exchange efficiency of the evaporator 10 is restored to a better state and the cooling effect is guaranteed.

[0060] This configuration allows for the adjustment of the opening of the first control valve 40 by calculating the superheat, thereby regulating the flow rate of the phase change medium in the cooling circuit 99. This results in higher control precision, higher heat exchange efficiency, and improved reliability of the evaporative cooling system 100.

[0061] In some embodiments of the present invention, such as Figure 1 As shown, the evaporative cooling system 100 of the bearing of the hydro-generator set also includes: a third temperature sensor 83, a second pressure sensor 92, a second control valve (not shown in the figure), and a controller (not shown in the figure). The third temperature sensor 83 and the second pressure sensor 92 are both located between the condenser 20 and the drive pump 30, and are respectively configured to detect the temperature and pressure of the phase change medium at the outlet of the condenser 20. The second control valve is located in the condenser 20. The second control valve is connected to the controller and configured to control the flow rate of the cooling water in the condenser 20. The controller is connected to the third temperature sensor 83 and the second pressure sensor 92, and is configured to calculate the subcooling of the phase change medium based on the information fed back by the third temperature sensor 83 and the second pressure sensor 92, and control the opening degree of the second control valve based on the subcooling.

[0062] In this embodiment, the controller is connected to both the third temperature sensor 83 and the second pressure sensor 92. In some embodiments of this application, the controller is also connected to both the third temperature sensor 83 and the second pressure sensor 92 via wires. In some embodiments of this application, the controller is also connected to the second control valve via wires.

[0063] The third temperature sensor 83 and the second pressure sensor 92 are both located between the condenser 20 and the drive pump 30. The third temperature sensor 83 can detect the temperature of the phase change medium at the outlet of the condenser 20, and the second pressure sensor 92 can detect the pressure of the phase change medium at the outlet of the condenser 20.

[0064] The second control valve is located in the condenser 20. The second control valve can control the flow rate of the cooling water in the condenser 20. As some embodiments of this application, the second control valve is located in the second flow channel of the condenser 20. The second control valve can control the flow rate of the cooling water in the second flow channel.

[0065] The controller can calculate the subcooling of the phase change medium based on the information fed back by the third temperature sensor 83 and the second pressure sensor 92, and control the opening degree of the second control valve based on the subcooling.

[0066] Understandably, supercooling is the difference between the saturation temperature (condensation temperature) of the liquid phase change medium and the actual temperature of the liquid phase change medium.

[0067] As some embodiments of this application, the controller can calculate the subcooling degree based on the third temperature sensor 83 and the second pressure sensor 92. When the subcooling degree is higher than the target value, the controller can control the second control valve to reduce the opening degree to reduce the flow rate of cooling water and reduce the condensation intensity. When the subcooling degree is lower than the target value, the controller can control the second control valve to increase the opening degree to increase the flow rate of cooling water and increase the condensation intensity.

[0068] This configuration allows for the adjustment of the opening of the second control valve by calculating the subcooling, thereby regulating the cooling water flow rate in the condenser 20, precisely adjusting the condensation intensity, and ensuring that the drive pump 30 is always within a safe operating range, which is beneficial to the reliability of the evaporative cooling system 100.

[0069] As some embodiments of this application, the controller can continuously collect the pressure value (i.e., condensing pressure) of the second pressure sensor 92. When the pressure value is continuously lower than the lower limit of the normal value (e.g., lower than 15% of the normal operating range and lasting for more than 30 minutes), the controller determines that the system is leaking and outputs a leak alarm signal. When the pressure value is abnormally high (e.g., higher than 15% of the normal operating range and lasting for more than 30 minutes), the controller determines that the condenser 20 is scaled or blocked and outputs a scale warning signal for the condenser 20. When the pressure value is abnormally low and the subcooling at the inlet of the drive pump 30 decreases synchronously, the controller determines that the phase change medium is leaking and outputs a working fluid leak warning signal.

[0070] As some embodiments of this application, the controller can verify the correctness of the superheat based on the value of the first pressure sensor 91 to ensure the accuracy of superheat control.

[0071] In some embodiments of the present invention, the evaporative cooling system 100 of the bearing of the hydro-generator set further includes: a controller, which is connected to both the first control valve 40 and the drive pump 30 and configured to synchronously adjust the speed of the drive pump 30 according to the expected change in the opening of the first control valve 40 when it is necessary to control the opening of the first control valve 40.

[0072] In other words, when it is necessary to control the opening of the first control valve 40, the controller can synchronously adjust the speed of the drive pump 30 according to the expected change in the opening of the first control valve 40.

[0073] As some embodiments of this application, when it is necessary to increase the opening of the first control valve 40 to increase the flow of the bypass circuit 98 (e.g., when the superheat is low), the controller simultaneously calculates the reduction in the rotational speed of the drive pump 30 based on the expected increase in the opening of the first control valve 40. Since the system's sensitivity to the opening of the first control valve 40 increases after the rotational speed of the drive pump 30 decreases, the actual increase in the opening of the first control valve 40 required to achieve the same superheat target is significantly reduced. In other words, under the premise of meeting the superheat control requirements, the controller preferentially adopts the bypass principle, that is, while ensuring that the superheat is not lower than the safety threshold, the opening of the first control valve 40 is limited to a smaller value that meets the superheat requirements.

[0074] As some embodiments of this application, when the controller issues a command to control the opening degree of the first control valve 40, it calculates the adjustment amount of the speed of the drive pump 30 according to the formula: ΔN_pump = -k_coupling · ΔV_valve, where ΔV_valve is the increase in the opening degree of the first control valve 40, k_coupling is the coupling coefficient (calibrated by system characteristic experiments, with a typical value of 0.3~0.8), and the negative sign indicates that the speed of the drive pump 30 decreases.

[0075] As some embodiments of this application, the coupling coefficient k_coupling can be calibrated on-site. Taking k_coupling = 0.5 means that for every 10% increase in valve opening, the pump speed will decrease by 5% simultaneously.

[0076] As some embodiments of this application, the controller can not only adjust the speed of the drive pump 30 according to the information fed back by the first temperature sensor 81, but also synchronously adjust the speed of the drive pump 30 according to the expected change in the opening degree of the first control valve 40.

[0077] This configuration allows for simultaneous adjustment of the speed of the drive pump 30 while adjusting the opening of the first control valve 40. This reduces ineffective bypass flow and lowers the output of the drive pump 30, thereby reducing energy waste. Furthermore, it enables a smooth transition of the phase change medium flow rate during the adjustment process of the evaporative cooling system 100, reducing the risk of sudden changes in the phase change medium flow rate and improving control stability.

[0078] As some embodiments of this application, in the initial state, the drive pump 30 speed is 80%, the first control valve 40 opening is 10%, and the superheat is 4°C (too low, needs to be increased to 6~8°C). The controller determines that the opening of the first control valve 40 needs to be increased to increase the superheat. At the same time as issuing the command to increase the opening of the first control valve 40, the controller simultaneously reduces the speed of the drive pump 30 to 75%. Since the total flow of the drive pump 30 is reduced, to achieve the same superheat target, the opening of the first control valve 40 only needs to be increased to 17%, with a smaller reduction and a smoother process.

[0079] As some embodiments of this application, the controller is constructed as an industrial-grade PLC with a scan cycle of 50ms to ensure timely response during sudden changes in thermal load. In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0080] In the description of this invention, "first feature" and "second feature" may include one or more of the features.

[0081] In the description of this invention, "a plurality of" means two or more.

[0082] In the description of this invention, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or it may include the first and second features not being in direct contact but being in contact through another feature between them.

[0083] In the description of this invention, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature.

[0084] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0085] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An evaporative cooling system for the bearings of a hydro-generator set, characterized in that, include: An evaporator, a condenser, and a drive pump are provided. The condenser, the evaporator, and the drive pump form a cooling circuit. The evaporator is arranged in the oil sump of the bearing. A phase change medium flows inside the cooling circuit. The evaporator is configured to absorb heat through the evaporation of the phase change medium to cool the lubricating oil flowing through the bearing. The condenser is configured to condense the vaporized phase change medium into a liquid state. A first control valve, the drive pump, and the first control valve form a bypass circuit, the first control valve being configured to control the flow rate of the bypass circuit.

2. The evaporative cooling system for the bearings of a hydro-generator unit according to claim 1, characterized in that, Also includes: A liquid storage tank is located upstream of the drive pump, downstream of the condenser, and downstream of the first control valve.

3. The evaporative cooling system for the bearings of a hydro-generator set according to claim 1, characterized in that, Also includes: A sight glass is disposed between the condenser and the drive pump, and is configured to observe the flow state and phase state of the phase change medium.

4. The evaporative cooling system for the bearings of a hydro-generator set according to claim 3, characterized in that, The sight glass includes a color-changing indicator configured to change color in response to changes in the moisture content of the phase change medium.

5. The evaporative cooling system for the bearings of a hydro-generator unit according to claim 1, characterized in that, The condenser has a first flow channel and a second flow channel. The first flow channel, the evaporator, and the drive pump form the cooling circuit. The second flow channel is configured to allow river water to flow through it.

6. The evaporative cooling system for the bearings of a hydro-generator unit according to any one of claims 1-5, characterized in that, Also includes: A first temperature sensor and a controller are provided. The first temperature sensor is located in the oil tank and configured to detect the temperature in the oil tank. The controller is connected to both the first temperature sensor and the drive pump and is configured to adjust the speed of the drive pump based on the information fed back by the first temperature sensor.

7. The evaporative cooling system for the bearings of a hydro-generator unit according to any one of claims 1-5, characterized in that, Also includes: A spindle speed sensor and a controller are provided. The spindle speed sensor is connected to the controller. The spindle speed sensor is configured to detect the speed of the spindle. The controller is configured to adjust the speed of the drive pump based on the information fed back by the spindle speed sensor.

8. The evaporative cooling system for the bearings of a hydro-generator unit according to any one of claims 1-5, characterized in that, Also includes: A second temperature sensor, a first pressure sensor, and a controller are provided. The second temperature sensor and the first pressure sensor are located between the evaporator and the condenser and are configured to detect the temperature and pressure of the phase change medium at the outlet of the evaporator. The controller is connected to both the second temperature sensor and the first pressure sensor and is configured to calculate the superheat of the phase change medium based on the information fed back by the second temperature sensor and the first pressure sensor, and control the opening degree of the first control valve based on the superheat.

9. The evaporative cooling system for the bearings of a hydro-generator unit according to any one of claims 1-5, characterized in that, Also includes: The system includes a third temperature sensor, a second pressure sensor, a second control valve, and a controller. The third temperature sensor and the second pressure sensor are both located between the condenser and the drive pump, and are respectively configured to detect the temperature and pressure of the phase change medium at the outlet of the condenser. The second control valve is located in the condenser. The second control valve is connected to the controller and configured to control the flow rate of the cooling water in the condenser. The controller is connected to both the third temperature sensor and the second pressure sensor and is configured to calculate the subcooling of the phase change medium based on the information fed back by the third temperature sensor and the second pressure sensor, and control the opening degree of the second control valve based on the subcooling.

10. The evaporative cooling system for the bearings of a hydro-generator unit according to any one of claims 1-5, characterized in that, Also includes: The controller is connected to both the first control valve and the drive pump and is configured to synchronously adjust the speed of the drive pump according to the expected change in the opening of the first control valve when it is necessary to control the opening of the first control valve.

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