Two-stage cooling system suitable for wind turbine generator gearbox

Abstract

The utility model discloses a two-stage cooling system suitable for a wind turbine generator gearbox, which is used for realizing efficient cooling of high-temperature lubricating oil in the wind turbine generator gearbox and improving the operation performance and the reliability of the gearbox. The system mainly comprises a gear box, an intermediate heat exchanger and an air cooling heat exchanger, wherein the gear box and the intermediate heat exchanger are located in a wind turbine generator cabin; the intermediate heat exchanger is provided with a high-temperature lubricating oil heat exchange side and a low-temperature working medium heat exchange side. Lubricating oil flows to the high-temperature side of the intermediate heat exchanger from the gear box through a pipeline and returns to the gear box after being cooled, and a lubricating oil heat dissipation cooling loop is formed. Meanwhile, the air cooling heat exchanger is connected with the low-temperature side of the intermediate heat exchanger through a pipeline to form a heat dissipation cooling loop of the phase change working medium. By introducing a two-stage cooling mechanism, the cooling efficiency of the gear box is effectively improved, the stable operation of the wind turbine generator under various environmental conditions is ensured, the maintenance cost is reduced, and the service life of equipment is prolonged.

Description

Technical Field

[0001] The utility model belongs to the technical field of wind power generation, and relates to the design and optimization of a wind turbine gearbox cooling system. Specifically, it is a two-stage cooling system suitable for a wind turbine gearbox, and aims to solve the problem of lubricating oil overheating in a gearbox under a high temperature environment by improving heat exchange efficiency. It can effectively realize efficient cooling of high-temperature lubricating oil in a wind turbine gearbox, and improve the operating performance and reliability of the gearbox. Background Art

[0002] Wind power generation is the process of converting wind energy into electrical energy. Its core equipment is the wind turbine generator set, in which the wind turbine gearbox is an important component of the wind turbine generator set. Its function is to convert the low-speed and high-torque of the wind wheel into the high-speed and low-torque of the generator, thereby realizing the effective utilization of wind energy. During the operation of the wind turbine set, the mechanical bearings inside the wind turbine gearbox will generate a large amount of waste heat due to the rotational friction loss. This waste heat will not only affect the normal operation of the gearbox, but also cause energy waste. Therefore, for the waste heat treatment of the wind turbine gearbox, the prior art usually uses a pump-driven oil circulation system for collection and transmission, which can not only collect the waste heat of the mechanical bearings, but also lubricate the bearings, thereby reducing the friction coefficient and wear degree of the bearings, and improving the life and efficiency of the gearbox. In this process, the lubricating oil absorbs heat and heats up. When the temperature is high and exceeds a certain range, it will affect the performance and stability of the lubricating oil, and even cause the oxidation and deterioration of the lubricating oil, thereby reducing the lubrication effect and increasing the risk of gearbox failure. At this time, it is necessary to transfer the heat to the outside through the cooling system, so that the temperature of the lubricating oil is kept within a reasonable range to ensure the normal operation of the gearbox and the stability of the equipment.

[0003] The lubrication and cooling system outside the wind turbine gearbox can be roughly divided into several parts, including the lubrication system, cooling system and sensor. The lubrication system mainly includes the oil suction pipe, motor pump, motor, filter, connecting valve block, temperature control valve and corresponding connecting hose. Some wind turbine gearboxes also include gear pumps. The cooling system can be divided into two forms: air cooling and water cooling. At present, air cooling is more commonly used on wind turbine gearboxes. Air cooling includes fans, motors and corresponding connecting hoses. In the air cooling form of the wind turbine lubrication and cooling system, the lubricating oil is sucked out from the gearbox oil pool through the motor pump and the mechanical pump (running when the gearbox rotates), and the lubricating oil reaches the temperature control valve after passing through the filter. The temperature control valve can automatically control the flow direction of the lubricating oil according to the oil temperature of the lubricating oil passing through. The sensor is a monitoring device of the lubrication and cooling system, which is used to measure the temperature, pressure, flow and other parameters of the lubricating oil in real time, and transmit the data to the control system for data analysis and fault diagnosis. The role of the sensor is to ensure the safe and stable operation of the lubrication and cooling system, timely detect and handle abnormal conditions, and improve the reliability and performance of the gearbox.

[0004] For large wind turbines, due to their high power, high speed and high torque, the waste heat of their gearboxes also increases accordingly. Especially in hot seasons, the gearbox oil temperature is more likely to be too high. When the heat inside the cabin is high and the heat exchange with the external fresh air is not smooth, the ambient air temperature is usually high, which will reduce the effect of air cooling and make it difficult to dissipate the heat of the lubricating oil. At the same time, when the high-temperature lubricating oil dissipates heat to the air, due to the low convection heat transfer coefficient on the oil side and the small heat exchange area, the generated heat cannot be fully dissipated into the ambient air, resulting in a further increase in the temperature of the lubricating oil. When the lubricating oil temperature reaches a high temperature, the control system will perform power limiting protection, resulting in the inability to increase the power of the wind turbine and serious power generation losses. In addition, high-temperature lubricating oil will accelerate the aging and deterioration of the lubricating oil, reduce the viscosity and lubricating performance of the lubricating oil, increase the wear and noise of the gearbox, and affect the life and efficiency of the gearbox.

[0005] In summary, the existing traditional air cooling method can no longer meet the heat transfer problem of wind turbine gearboxes under high temperature and high heat flow conditions, and it is urgent to develop a more effective cooling solution to achieve efficient heat dissipation of the wind turbine gearbox lubrication cooling system. Therefore, how to effectively achieve efficient heat dissipation of the wind turbine lubrication cooling system, which can effectively reduce the gearbox oil temperature and maintain the system operation stability and reliability, has become an urgent problem to be solved. Utility Model Content

[0006] (I) Purpose of the utility model

[0007] In view of the technical bottleneck that the existing traditional wind power gearbox cooling system has insufficient heat exchange, resulting in excessive lubricating oil temperature, which in turn causes power limiting protection or even shutdown of the wind power system, the purpose of the utility model is to develop a two-stage cooling system suitable for wind turbine gearboxes with stronger heat exchange capacity, so as to achieve efficient cooling of high-temperature lubricating oil in wind power gearboxes. The system achieves efficient cooling by optimizing the heat transfer capacity matching of each heat exchange link in the cooling process of high-temperature gearbox lubricating oil, thereby maximizing the overall heat transfer capacity. In this way, the utility model can significantly increase the limit threshold of ambient temperature, and achieve the purpose of natural cooling throughout the year in hot areas. Through this efficient cooling method, the utility model can improve the reliability and stability of the wind power system, reduce power restrictions or shutdowns caused by excessive temperature, thereby improving the overall power generation efficiency and economy of the wind power system, and providing strong support for the further development and application of wind power generation technology.

[0008] (II) Technical solution

[0009] In order to achieve the purpose of this utility model, the utility model adopts the following technical solutions:

[0010] A two-stage cooling system for a wind turbine gearbox is used to achieve efficient cooling of high-temperature lubricating oil in the wind turbine gearbox and improve the operating performance and reliability of the gearbox. The system comprises at least one gearbox, an intermediate heat exchanger and an air-cooled heat exchanger, and is characterized in that:

[0011] The gear box and the intermediate heat exchanger are arranged inside the nacelle of the wind turbine set, and the air-cooled heat exchanger is arranged outside the nacelle of the wind turbine set, and the arrangement position of the air-cooled heat exchanger is higher than the arrangement position of the intermediate heat exchanger;

[0012] The intermediate heat exchanger comprises at least a high-temperature lubricating oil heat exchange side and a low-temperature working medium heat exchange side, for realizing heat exchange between the lubricating oil with a higher temperature flowing into the high-temperature lubricating oil heat exchange side and the phase-change working medium with a lower temperature flowing into the low-temperature working medium heat exchange side;

[0013] The lubricating oil outlet of the gear box is connected to the inlet of the high-temperature lubricating oil heat exchange side through a pipeline, and the outlet of the high-temperature lubricating oil heat exchange side is connected to the lubricating oil inlet of the gear box through a pipeline, so that a lubricating oil heat dissipation cooling circuit is formed between the gear box and the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger through the pipeline;

[0014] The liquid working fluid outlet of the air-cooled heat exchanger is connected to the working fluid inlet of the low-temperature working fluid heat exchange side, and the working fluid outlet of the low-temperature working fluid heat exchange side is connected to the gaseous working fluid inlet of the air-cooled heat exchanger, so that a phase change working fluid heat dissipation cooling circuit is formed between the air-cooled heat exchanger and the low-temperature working fluid heat exchange side of the intermediate heat exchanger through pipelines.

[0015] Preferably, a first bypass pipeline is arranged on the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger, between its inlet and outlet, and at least one first stop valve is provided on the first bypass pipeline. The first stop valve is used to control the lubricating oil bypass flow in the lubricating oil heat dissipation cooling circuit to adjust the heat exchange amount and heat exchange efficiency of the lubricating oil in the intermediate heat exchanger, thereby realizing precise control of the lubricating oil temperature.

[0016] Furthermore, when the first stop valve is in a closed state, the lubricating oil bypass flow in the lubricating oil heat dissipation cooling circuit is zero, and the lubricating oil all enters the intermediate heat exchanger to fully exchange heat with the low-temperature working medium, thereby reducing the temperature of the lubricating oil; when the first stop valve is in an open state, the lubricating oil bypass flow in the lubricating oil heat dissipation cooling circuit is determined by the opening size of the first stop valve, and part of the lubricating oil enters the intermediate heat exchanger and part of the lubricating oil enters the first bypass pipeline, thereby reducing the heat exchange amount and heat exchange efficiency of the lubricating oil in the intermediate heat exchanger.

[0017] Furthermore, at least one second stop valve is provided on the connecting pipeline between the lubricating oil outlet of the gear box and the inlet of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger, and the second stop valve is arranged near the inlet position of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger. The second stop valve is used to control the flow entering the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger and adjust the flow rate of the lubricating oil according to the cooling requirements of the system, thereby realizing precise control of the lubricating oil temperature.

[0018] Furthermore, when the two-stage cooling system is in the initial startup stage or in a low-temperature environment, the first stop valve is in an open state and the second stop valve is in a closed state, so that all the lubricating oil in the lubricating oil heat dissipation cooling circuit bypasses the intermediate heat exchanger through the first bypass line and directly flows back into the gear box, thereby avoiding excessive cooling of the lubricating oil in the intermediate heat exchanger, which causes an increase in viscosity and a decrease in lubrication performance.

[0019] Preferably, at least one lubricating oil pump is provided on the connecting pipeline between the lubricating oil outlet of the gear box and the inlet of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger, and the lubricating oil pump is arranged near the lubricating oil outlet position of the gear box, and the lubricating oil pump is used to provide lubricating oil flow power in the lubricating oil heat dissipation cooling circuit.

[0020] Furthermore, a fine filter and a coarse filter located downstream of the lubricating oil pump are sequentially provided on the connecting pipeline between the lubricating oil outlet of the gear box and the inlet of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger. The filtering accuracy of the fine filter is higher than that of the coarse filter. The fine filter and the coarse filter are used to filter the lubricating oil in the lubricating oil heat dissipation cooling circuit in a graded filtering manner to remove impurities and particles in the lubricating oil. A second bypass pipeline is provided between the inlet and the outlet of the fine filter. At least one safety valve is provided on the second bypass pipeline. When the filter element of the fine filter causes the lubricating oil pressure in the circuit to increase to a preset threshold value due to filtering particles, the safety valve automatically opens under the action of pressure, so that the lubricating oil bypasses the fine filter through the second bypass pipeline and enters the downstream coarse filter, thereby avoiding a reduction in the lubricating oil flow and an increase in the lubricating oil temperature in the lubricating oil heat dissipation cooling circuit.

[0021] Preferably, at least a temperature sensor, a pressure sensor and a flow sensor are provided on the connecting pipeline between the lubricating oil outlet of the gear box and the inlet of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger, and the temperature sensor, pressure sensor and flow sensor are arranged near the lubricating oil outlet position of the gear box for real-time monitoring of the lubricating oil temperature, pressure and flow parameters in the lubricating oil heat dissipation cooling circuit to meet the heat dissipation requirements of the gear box under different working conditions.

[0022] Preferably, at least one liquid reservoir is provided on the connecting pipeline between the liquid working fluid outlet of the air-cooled heat exchanger and the working fluid inlet on the low-temperature working fluid heat exchange side of the intermediate heat exchanger. The liquid reservoir is used to store and regulate the liquid working fluid condensed by the air-cooled heat exchanger during the cooling cycle to ensure that sufficient cooling medium is supplied to the intermediate heat exchanger to achieve continuous and effective circulation and heat exchange, and is used to buffer system pressure fluctuations and absorb the expansion of the liquid working fluid in the cooling cycle, thereby protecting the system from damage caused by liquid shock.

[0023] Preferably, the air-cooled heat exchanger comprises at least a gaseous working medium heat exchange side and a fan arranged therewith, which is used to realize heat exchange between the gaseous working medium with a higher temperature passing into the gaseous working medium heat exchange side and the ambient air with a lower temperature passing into the fan, the inlet of the gaseous working medium heat exchange side of the air-cooled heat exchanger is connected to the working medium outlet of the low-temperature working medium heat exchange side of the intermediate heat exchanger, and the outlet of the gaseous working medium heat exchange side of the air-cooled heat exchanger is connected to the liquid working medium outlet of the air-cooled heat exchanger, so that the air-cooled heat exchanger A phase-change working medium heat exchange cooling circuit is formed between the gaseous working medium heat exchange side and the liquid working medium outlet of the air-cooled heat exchanger through a pipeline; the inlet of the fan is connected to the external ambient air, and the outlet of the fan corresponds to the outer surface of the gaseous working medium heat exchange side of the air-cooled heat exchanger, so that the fan can blow the external ambient air to the outer surface of the gaseous working medium heat exchange side of the air-cooled heat exchanger, thereby accelerating the heat exchange rate between the gaseous working medium and the ambient air, promoting the liquefaction of the gaseous working medium, and improving the circulation efficiency of the phase-change working medium.

[0024] (III) Technical Effect

[0025] Compared with the prior art, the two-stage cooling system of the utility model applicable to the gearbox of a wind turbine has the following beneficial and significant technical effects:

[0026] (1) Reduced lubricating oil circulation resistance, increased circulation flow, and reduced temperature rise. The utility model changes the cooling method of the gearbox lubricating oil from flowing through the existing air-cooled radiator to flowing through the intermediate heat exchanger, and the flow resistance of the intermediate heat exchanger is significantly lower than the flow resistance of the air-cooled radiator. Therefore, the circulation resistance of the lubricating oil is greatly reduced, thereby increasing the circulation flow of the lubricating oil, reducing the temperature rise of the lubricating oil, and ensuring the lubricating performance of the lubricating oil and the operating efficiency of the gearbox.

[0027] (2) The stability of the gearbox oil flow is improved, and no valve switching control is required to maintain a constant flow cycle, which is conducive to adapting to sudden changes in heat consumption. Since the utility model uses a phase-change working fluid as the low-temperature working fluid of the intermediate heat exchanger, the phase-change working fluid realizes a liquid-gas phase change in the intermediate heat exchanger, thereby realizing a large amount of heat transfer and release, so that the temperature of the lubricating oil is effectively controlled in the intermediate heat exchanger, and there is no need to set a valve in the lubricating oil circulation loop for switching control, thereby ensuring the stability of the lubricating oil flow, and at the same time, it is also conducive to adapting to sudden changes in heat consumption of wind turbines and improving the response speed of the system.

[0028] (3) The phase-change working fluid heat dissipation cooling circuit is used to provide a stable temperature boundary for the gearbox lubricating oil, thereby improving the system operation stability. Since the utility model adopts an air-cooled heat exchanger as a cooling device for the phase-change working fluid, the air-cooled heat exchanger can utilize the external wind force and temperature difference to enhance the heat exchange rate between the gaseous working fluid and the ambient air, promote the liquefaction of the gaseous working fluid, thereby reducing the temperature of the phase-change working fluid and improving the circulation efficiency of the phase-change working fluid. At the same time, since the pipeline length between the air-cooled heat exchanger and the intermediate heat exchanger is relatively short, the flow resistance of the phase-change working fluid in the pipeline is relatively small, thereby reducing the pressure loss of the phase-change working fluid and improving the heat exchange effect of the phase-change working fluid.

[0029] (4) The use of phase change heat transfer can improve the heat dissipation capacity of the air-cooled radiator and reduce the temperature of the gearbox lubricating oil. Since the utility model uses a phase change medium as the low-temperature medium of the intermediate heat exchanger, the phase change medium realizes a liquid-gas phase change in the intermediate heat exchanger, thereby realizing a large amount of heat transfer and release, so that the temperature of the lubricating oil is effectively controlled in the intermediate heat exchanger.

[0030] (5) The phase change system transfers the heat of the gearbox oil to the air-cooled heat exchanger under approximately isothermal conditions, and the temperature rise is small. Since the utility model uses a phase change medium as the low-temperature medium of the intermediate heat exchanger, the phase change medium realizes a liquid-gas phase change in the intermediate heat exchanger, and the temperature of the phase change medium is effectively reduced in the air-cooled heat exchanger. Since the temperature change of the phase change medium during the liquid-gas phase change process is very small, the phase change system transfers the heat of the oil to the air-cooled heat exchanger under approximately isothermal conditions, thereby realizing efficient cooling of the oil and reducing the temperature rise of the oil.

[0031] (6) The phase change system has a small circulation flow, small flow resistance, and a small pipe diameter. The product structure is compact and occupies a small area, which is conducive to transformation and implementation. It can be arranged in an overall or distributed manner according to the layout requirements. Since the utility model uses a phase change working fluid as the low-temperature working fluid of the intermediate heat exchanger, the circulation flow of the phase change system is small, thereby reducing the flow resistance of the phase change system and improving the operating efficiency of the phase change system. At the same time, since the circulation flow of the phase change system is small, the pipe diameter of the phase change system is also small, thereby reducing the volume and weight of the phase change system and saving space and materials.

[0032] (7) The phase-change high-efficiency cooling medium increases power density, the system is pump-free, and operation and maintenance costs are reduced. Since the utility model utilizes gravity to achieve the natural circulation of liquid and gaseous working fluids in the phase-change working fluid heat dissipation cooling circuit, no additional pumps or fans are required, thereby reducing the energy consumption and noise of the system, improving the operating efficiency and stability of the system, and also reducing the operation and maintenance costs and difficulty of the system, and improving the reliability and safety of the system.

[0033] (8) Using non-toxic, non-conductive, and non-corrosive working fluids, which is safer. Since the utility model uses a phase-change working fluid as the low-temperature working fluid of the intermediate heat exchanger, the selection range of the phase-change working fluid is relatively wide, and a working fluid with a lower boiling point and higher specific heat can be selected according to actual needs, such as ammonia, propane, butane, etc. These working fluids are non-toxic, non-conductive, and non-corrosive, thereby improving the safety and environmental protection of the system and avoiding harm and damage to personnel and equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Shown is a schematic diagram of a two-stage cooling system suitable for a wind turbine gearbox of the utility model;

[0035] Description of reference numerals:

[0036] Gear box 1, lubricating oil pump 2, fine filter 3, coarse filter 4, intermediate heat exchanger 5, second stop valve 6, first stop valve 7, safety valve 8, air-cooled heat exchanger 9, liquid storage tank 10. DETAILED DESCRIPTION

[0037] In order to better understand the present utility model, the content of the present utility model is further explained in conjunction with the embodiments below. In the accompanying drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of the present utility model, not all of them. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present utility model, and should not be understood as limitations on the present utility model. Based on the embodiments in the present utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present utility model. The structure and technical solution of the present utility model are further described in detail below in conjunction with the accompanying drawings, and an embodiment of the present utility model is given.

[0038] As a preferred embodiment of the present invention, Figure 1As shown, the utility model is suitable for a two-stage cooling system of a wind turbine gearbox, which is used to achieve efficient cooling of high-temperature lubricating oil in the wind turbine gearbox and improve the operating performance and reliability of the gearbox, and includes a gearbox 1, an oil pump 2, a fine filter 3, a coarse filter 4, an intermediate heat exchanger 5, a second stop valve 6, a first stop valve 7, a safety valve 8, an air-cooled heat exchanger 9, a liquid reservoir 10 and other components.

[0039] In this embodiment, the gear box 1 and the intermediate heat exchanger 5 are arranged inside the wind turbine cabin, and the air-cooled heat exchanger 9 is arranged outside the wind turbine cabin, and the arrangement position of the air-cooled heat exchanger 9 is higher than the arrangement position of the intermediate heat exchanger 5, so as to utilize the gravity to realize the natural circulation of the liquid working medium and the gaseous working medium in the phase change working medium heat dissipation cooling circuit, without the need for an additional pump or fan, thereby reducing the energy consumption and noise of the system and improving the operation efficiency and stability of the system. At the same time, since the length of the pipeline between the air-cooled heat exchanger 9 and the intermediate heat exchanger 5 is short, the flow resistance of the phase change working medium in the pipeline is small, thereby reducing the pressure loss of the phase change working medium and improving the circulation efficiency and heat exchange effect of the phase change working medium. In addition, since the air-cooled heat exchanger 9 is arranged outside the wind turbine cabin, the external wind force and temperature difference can be used to enhance the heat exchange rate between the gaseous working medium and the ambient air, promote the liquefaction of the gaseous working medium, thereby reducing the temperature of the phase change working medium and improving the circulation efficiency of the phase change working medium.

[0040] The intermediate heat exchanger 5 includes at least a high-temperature lubricating oil heat exchange side and a low-temperature working fluid heat exchange side, which are used to achieve heat exchange between the lubricating oil with a higher temperature flowing into the high-temperature lubricating oil heat exchange side and the phase-change working fluid with a lower temperature flowing into the low-temperature working fluid heat exchange side. As a preferred solution, a wall heat exchanger structure is used between the high-temperature lubricating oil heat exchange side and the low-temperature working fluid heat exchange side of the intermediate heat exchanger 5 to increase the heat exchange area and heat exchange efficiency, while also reducing the volume and weight of the heat exchanger, saving space and materials. The heat exchange method between the high-temperature lubricating oil heat exchange side and the low-temperature working fluid heat exchange side of the intermediate heat exchanger 5 is countercurrent heat exchange, that is, the flow directions of the lubricating oil and the phase-change working fluid are opposite to maximize the temperature difference between the lubricating oil and the phase-change working fluid, thereby improving the heat exchange effect and efficiency. The heat exchange process between the high-temperature lubricating oil heat exchange side and the low-temperature working fluid heat exchange side of the intermediate heat exchanger 5 is isobaric heat exchange, that is, the pressure of the lubricating oil and the phase change working fluid remains unchanged to avoid pressure loss of the lubricating oil and the phase change working fluid, thereby ensuring the fluidity and circulation of the lubricating oil and the phase change working fluid.

[0041] The lubricating oil outlet of the gearbox 1 is connected to the inlet of the high-temperature lubricating oil heat exchange side through a pipeline, and the outlet of the high-temperature lubricating oil heat exchange side is connected to the lubricating oil inlet of the gearbox 1 through a pipeline, so that a lubricating oil heat dissipation cooling circuit is formed between the gearbox 1 and the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger 5 through the pipeline. The function of the lubricating oil heat dissipation cooling circuit is to transfer the waste heat generated inside the gearbox 1 to the intermediate heat exchanger 5 through the lubricating oil, and exchange heat with the phase change working medium, thereby reducing the temperature of the lubricating oil, improving the lubricating performance of the lubricating oil, and ensuring the normal operation of the gearbox 1 and the stability of the equipment. The parameters such as the lubricating oil flow, pressure, and temperature in the lubricating oil heat dissipation cooling circuit can be monitored and controlled in real time through corresponding sensors to realize intelligent management and control of the lubricating oil heat dissipation cooling circuit.

[0042] The liquid working medium outlet of the air-cooled heat exchanger 9 is connected to the working medium inlet of the low-temperature working medium heat exchange side, and the working medium outlet of the low-temperature working medium heat exchange side is connected to the gaseous working medium inlet of the air-cooled heat exchanger 9, so that a phase-change working medium heat dissipation cooling circuit is formed between the air-cooled heat exchanger 9 and the low-temperature working medium heat exchange side of the intermediate heat exchanger 5 through a pipeline. The function of the phase-change working medium heat dissipation cooling circuit is to transfer the waste heat of the lubricating oil absorbed in the intermediate heat exchanger 5 to the air-cooled heat exchanger 9 through the phase-change working medium, and exchange heat with the ambient air, thereby reducing the temperature of the phase-change working medium, improving the circulation efficiency of the phase-change working medium, and ensuring the normal operation of the intermediate heat exchanger 5 and the stability of the equipment. The phase-change working medium in the phase-change working medium heat dissipation cooling circuit is a working medium with a lower boiling point and higher specific heat, such as ammonia, propane, butane, etc., which can achieve liquid-gas phase change at a lower temperature and pressure, thereby realizing a large amount of heat transfer and release. The parameters such as the phase change working fluid flow, pressure, temperature, etc. in the phase change working fluid heat dissipation cooling circuit can be monitored and controlled in real time through corresponding sensors to realize intelligent management and control of the phase change working fluid heat dissipation cooling circuit.

[0043] In this embodiment, a first bypass pipeline is arranged between the inlet and the outlet of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger 5, and at least one first stop valve 7 is arranged on the first bypass pipeline. The first stop valve 7 is used to control the bypass flow of the lubricating oil in the lubricating oil heat dissipation cooling circuit to adjust the heat exchange amount and heat exchange efficiency of the lubricating oil in the intermediate heat exchanger 5, thereby realizing accurate control of the lubricating oil temperature. At least one second stop valve 6 is also arranged on the connecting pipeline between the lubricating oil outlet of the gearbox 1 and the inlet of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger 5, and the second stop valve 6 is arranged near the inlet position of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger 5. The second stop valve 6 is used to control the flow entering the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger 5, and adjust the flow rate of the lubricating oil according to the cooling demand of the system, thereby realizing accurate control of the lubricating oil temperature.

[0044] When the first stop valve 7 is in the closed state, the bypass flow of the lubricating oil in the lubricating oil heat dissipation cooling circuit is zero, and the lubricating oil all enters the intermediate heat exchanger 5 to fully exchange heat with the low-temperature working medium, thereby reducing the temperature of the lubricating oil; when the first stop valve 7 is in the open state, the bypass flow of the lubricating oil in the lubricating oil heat dissipation cooling circuit is determined by the opening size of the first stop valve 7, and the lubricating oil partially enters the intermediate heat exchanger 5 and partially enters the first bypass pipeline, thereby reducing the heat exchange amount and heat exchange efficiency of the lubricating oil in the intermediate heat exchanger 5. When the two-stage cooling system is in the initial startup stage or in a low-temperature environment, the first stop valve 7 is in the open state and the second stop valve 6 is in the closed state, so that all the lubricating oil in the lubricating oil heat dissipation cooling circuit bypasses the intermediate heat exchanger 5 through the first bypass pipeline and directly flows back into the gear box 1, thereby avoiding excessive cooling of the lubricating oil in the intermediate heat exchanger 5, which leads to increased viscosity and decreased lubrication performance.

[0045] In this embodiment, at least one lubricating oil pump 2 is provided on the connecting pipeline between the lubricating oil outlet of the gear box 1 and the inlet of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger 5, and the lubricating oil pump 2 is arranged near the lubricating oil outlet position of the gear box 1, and the lubricating oil pump 2 is used to provide lubricating oil flow power in the lubricating oil heat dissipation cooling circuit. A fine filter 3 and a coarse filter 4 located downstream of the lubricating oil pump 2 are also provided in sequence on the connecting pipeline between the lubricating oil outlet of the gearbox 1 and the inlet of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger 5. The filtering accuracy of the fine filter 3 is higher than that of the coarse filter 4. The fine filter 3 and the coarse filter 4 are used to filter the lubricating oil in the lubricating oil heat dissipation cooling circuit in a graded filtering manner to remove impurities and particles in the lubricating oil; a second bypass pipeline is provided between the inlet and outlet of the fine filter 3, and at least one safety valve 8 is provided on the second bypass pipeline. When the filter element of the fine filter 3 causes the lubricating oil pressure in the circuit to increase to a preset threshold value due to filtering particles, the safety valve 8 automatically opens under the action of pressure, so that the lubricating oil bypasses the fine filter 3 through the second bypass pipeline and enters the downstream coarse filter 4, thereby avoiding a reduction in the lubricating oil flow and an increase in the lubricating oil temperature in the lubricating oil heat dissipation cooling circuit.

[0046] In addition, in this embodiment, a temperature sensor, a pressure sensor and a flow sensor are preferably provided on the connecting pipeline between the lubricating oil outlet of the gear box 1 and the inlet of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger 5, and the temperature sensor, pressure sensor and flow sensor are arranged near the lubricating oil outlet position of the gear box 1, and are used to monitor the lubricating oil temperature, pressure and flow parameters in the lubricating oil heat dissipation cooling circuit in real time to meet the heat dissipation requirements of the gear box under different working conditions.

[0047] At the same time, in this embodiment, at least one liquid reservoir 10 is provided on the connecting pipeline between the liquid working fluid outlet of the air-cooled heat exchanger 9 and the working fluid inlet on the low-temperature working fluid heat exchange side of the intermediate heat exchanger 5. The liquid reservoir 10 is used to store and regulate the liquid working fluid condensed by the air-cooled heat exchanger 9 during the cooling cycle to ensure that sufficient cooling medium is supplied to the intermediate heat exchanger 5 to achieve continuous and effective circulation and heat exchange, and to buffer system pressure fluctuations and absorb the expansion of the liquid working fluid in the cooling cycle, thereby protecting the system from damage caused by liquid shock.

[0048] In this embodiment, the air-cooled heat exchanger 9 includes at least a gaseous working medium heat exchange side and a fan arranged therewith, which is used to realize heat exchange between the gaseous working medium with a higher temperature introduced into the gaseous working medium heat exchange side and the ambient air with a lower temperature introduced into the fan. The inlet of the gaseous working medium heat exchange side of the air-cooled heat exchanger 9 is connected to the working medium outlet of the low-temperature working medium heat exchange side of the intermediate heat exchanger 5, and the outlet of the gaseous working medium heat exchange side of the air-cooled heat exchanger 9 is connected to the liquid working medium outlet of the air-cooled heat exchanger 9, so that the air-cooled heat exchanger A phase change working medium heat exchange cooling circuit is formed between the gaseous working medium heat exchange side of 9 and the liquid working medium outlet of the air-cooled heat exchanger 9 through a pipeline; the inlet of the fan is connected to the external ambient air, and the outlet of the fan corresponds to the outer surface of the gaseous working medium heat exchange side of the air-cooled heat exchanger 9, so that the fan can blow the external ambient air to the outer surface of the gaseous working medium heat exchange side of the air-cooled heat exchanger 9, thereby accelerating the heat exchange rate between the gaseous working medium and the ambient air, promoting the liquefaction of the gaseous working medium, and improving the circulation efficiency of the phase change working medium.

[0049] Compared with the existing traditional wind turbine gearbox cooling system, the high-temperature lubricating oil flowing out of the original gearbox is directly dissipated to the external environment through the air-cooled heat exchanger after filtering and other steps. The utility model adds an intermediate heat exchanger with stronger heat transfer capacity to quickly export the heat on the oil side.

[0050] Specifically, in the utility model, the high-temperature lubricating oil flowing out of the gear box 1 first exchanges heat with the low-temperature phase-change working fluid in the intermediate heat exchanger 5. Heat is transferred from the lubricating oil to the low-temperature phase-change working fluid, and the cooled lubricating oil returns to the gear box 1 to continue lubrication and cooling, while the low-temperature phase-change working fluid absorbs heat and then vaporizes. The two-phase flow working fluid enters the air-cooled heat exchanger 9 through the heat pipe cycle, exchanges heat with the cold air in the heat exchanger 9, and the phase-change working fluid releases heat and liquefies, and then flows back to the intermediate heat exchanger 5 along the heat pipe loop to absorb heat. Although the two-stage cooling scheme adds a heat exchange link, the thermal resistance of each heat exchange link is small, the total thermal resistance is smaller than the original scheme, and the heat exchange capacity is more significant.

[0051] The two-stage cooling system of the utility model does not change or connect to the original gearbox control system. The return oil flow and temperature are only guaranteed in the interface return oil pipeline. In view of the technical conditions of the unit of this scheme, in order to reduce maintenance costs and workload, the cold plate structure is improved through technology to achieve the heat dissipation goal by medium self-driving mode, without the need for pump drive. The heat dissipation goal is achieved by adding efficient heat exchange links, improving the cold plate structure, etc. The heat exchange medium in the newly added cycle can achieve self-driven operation, without the need for pump drive, reducing operation and maintenance costs.

[0052] Through the above embodiments, the purpose of the utility model is fully and effectively achieved. Those skilled in the art can understand that the utility model includes but is not limited to the contents described in the drawings and the above specific embodiments. Although the utility model has been described with respect to the most practical and preferred embodiments currently considered, it should be understood that the utility model is not limited to the disclosed embodiments, and any modification that does not deviate from the functional and structural principles of the utility model will be included in the scope of the claims.

Claims

1. A two-stage cooling system for a wind turbine gearbox, comprising at least a gearbox, an intermediate heat exchanger and an air-cooled heat exchanger, characterized in that: The gear box and the intermediate heat exchanger are arranged inside the nacelle of the wind turbine set, and the air-cooled heat exchanger is arranged outside the nacelle of the wind turbine set, and the arrangement position of the air-cooled heat exchanger is higher than the arrangement position of the intermediate heat exchanger; The intermediate heat exchanger comprises at least a high-temperature lubricating oil heat exchange side and a low-temperature working medium heat exchange side, for realizing heat exchange between the lubricating oil with a higher temperature flowing into the high-temperature lubricating oil heat exchange side and the phase-change working medium with a lower temperature flowing into the low-temperature working medium heat exchange side; The lubricating oil outlet of the gear box is connected to the inlet of the high-temperature lubricating oil heat exchange side through a pipeline, and the outlet of the high-temperature lubricating oil heat exchange side is connected to the lubricating oil inlet of the gear box through a pipeline, so that a lubricating oil heat dissipation cooling circuit is formed between the gear box and the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger through the pipeline; The liquid working fluid outlet of the air-cooled heat exchanger is connected to the working fluid inlet of the low-temperature working fluid heat exchange side, and the working fluid outlet of the low-temperature working fluid heat exchange side is connected to the gaseous working fluid inlet of the air-cooled heat exchanger, so that a phase change working fluid heat dissipation cooling circuit is formed between the air-cooled heat exchanger and the low-temperature working fluid heat exchange side of the intermediate heat exchanger through pipelines.

2. The two-stage cooling system for a wind turbine gearbox according to claim 1, characterized in that: On the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger, between its inlet and outlet, a first bypass pipeline is arranged, and at least one first stop valve is arranged on the first bypass pipeline. The first stop valve is used to control the lubricating oil bypass flow in the lubricating oil heat dissipation cooling circuit to adjust the heat exchange amount and heat exchange efficiency of the lubricating oil in the intermediate heat exchanger, thereby realizing precise control of the lubricating oil temperature.

3. The two-stage cooling system for a wind turbine gearbox according to claim 2, characterized in that: When the first stop valve is in a closed state, the lubricating oil bypass flow in the lubricating oil heat dissipation cooling circuit is zero, and the lubricating oil all enters the intermediate heat exchanger to fully exchange heat with the low-temperature working medium, thereby reducing the temperature of the lubricating oil; when the first stop valve is in an open state, the lubricating oil bypass flow in the lubricating oil heat dissipation cooling circuit is determined by the opening size of the first stop valve, and part of the lubricating oil enters the intermediate heat exchanger and part of the lubricating oil enters the first bypass pipeline, thereby reducing the heat exchange amount and heat exchange efficiency of the lubricating oil in the intermediate heat exchanger.

4. The two-stage cooling system for a wind turbine gearbox according to claim 2, characterized in that: At least one second stop valve is provided on the connecting pipeline between the lubricating oil outlet of the gear box and the inlet of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger, and the second stop valve is arranged near the inlet position of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger. The second stop valve is used to control the flow rate entering the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger and adjust the flow rate of the lubricating oil according to the cooling requirements of the system, thereby realizing precise control of the lubricating oil temperature.

5. The two-stage cooling system for a wind turbine gearbox according to claim 4, characterized in that: When the two-stage cooling system is in the initial startup stage or in a low-temperature environment, the first stop valve is in an open state and the second stop valve is in a closed state, so that all the lubricating oil in the lubricating oil heat dissipation cooling circuit bypasses the intermediate heat exchanger through the first bypass line and directly flows back into the gear box, thereby avoiding excessive cooling of the lubricating oil in the intermediate heat exchanger, which leads to increased viscosity and decreased lubrication performance.

6. The two-stage cooling system for a wind turbine gearbox according to claim 1, characterized in that: At least one lubricating oil pump is provided on the connecting pipeline between the lubricating oil outlet of the gear box and the inlet of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger, and the lubricating oil pump is arranged near the lubricating oil outlet position of the gear box to provide lubricating oil flow power in the lubricating oil heat dissipation cooling circuit.

7. The two-stage cooling system for a wind turbine gearbox according to claim 6, characterized in that: A fine filter and a coarse filter located downstream of the lubricating oil pump are also provided in sequence on the connecting pipeline between the lubricating oil outlet of the gear box and the inlet of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger. The filtering accuracy of the fine filter is higher than that of the coarse filter. The fine filter and the coarse filter are used to filter the lubricating oil in the lubricating oil heat dissipation cooling circuit in a graded filtering manner to remove impurities and particles in the lubricating oil. A second bypass pipeline is provided between the inlet and outlet of the fine filter. At least one safety valve is provided on the second bypass pipeline. When the filter element of the fine filter causes the lubricating oil pressure in the circuit to increase to a preset threshold value due to filtering particles, the safety valve automatically opens under the action of pressure, so that the lubricating oil bypasses the fine filter through the second bypass pipeline and enters the downstream coarse filter.

8. The two-stage cooling system for a wind turbine gearbox according to claim 1, characterized in that: At least a temperature sensor, a pressure sensor and a flow sensor are provided on the connecting pipeline between the lubricating oil outlet of the gear box and the inlet of the high-temperature lubricating oil heat exchange side of the intermediate heat exchanger, and the temperature sensor, pressure sensor and flow sensor are arranged near the lubricating oil outlet position of the gear box for real-time monitoring of the lubricating oil temperature, pressure and flow parameters in the lubricating oil heat dissipation cooling circuit to meet the heat dissipation requirements of the gear box under different working conditions.

9. The two-stage cooling system for a wind turbine gearbox according to claim 1, characterized in that: At least one liquid reservoir is provided on the connecting pipeline between the liquid working medium outlet of the air-cooled heat exchanger and the working medium inlet on the low-temperature working medium heat exchange side of the intermediate heat exchanger. The liquid reservoir is used to store and regulate the liquid working medium condensed by the air-cooled heat exchanger during the cooling cycle to ensure that sufficient cooling medium is supplied to the intermediate heat exchanger to achieve continuous and effective circulation and heat exchange, and is used to buffer system pressure fluctuations and absorb the expansion of the liquid working medium in the cooling cycle.

10. The two-stage cooling system for a wind turbine gearbox according to claim 1, characterized in that: The air-cooled heat exchanger comprises at least a gaseous working medium heat exchange side and a fan arranged therewith, for realizing heat exchange between the gaseous working medium with a higher temperature introduced into the gaseous working medium heat exchange side and the ambient air with a lower temperature introduced into the fan, the inlet of the gaseous working medium heat exchange side of the air-cooled heat exchanger is connected with the working medium outlet of the low-temperature working medium heat exchange side of the intermediate heat exchanger, and the outlet of the gaseous working medium heat exchange side of the air-cooled heat exchanger is connected with the liquid working medium outlet of the air-cooled heat exchanger, so that the gaseous working medium of the air-cooled heat exchanger A phase change working medium heat exchange cooling circuit is formed between the phase change working medium heat exchange side and the liquid working medium outlet of the air-cooled heat exchanger through a pipeline; the inlet of the fan is connected to the external ambient air, and the outlet of the fan corresponds to the outer surface of the gaseous working medium heat exchange side of the air-cooled heat exchanger, so that the fan can blow the external ambient air to the outer surface of the gaseous working medium heat exchange side of the air-cooled heat exchanger, thereby accelerating the heat exchange rate between the gaseous working medium and the ambient air, promoting the liquefaction of the gaseous working medium, and improving the circulation efficiency of the phase change working medium.

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