Wide-rotating-speed and large-bearing-capacity supercritical carbon dioxide dynamic-static pressure tilting pad bearing system

Abstract

The invention relates to the technical field of air bearings, in particular to a wide-rotating-speed large-bearing supercritical carbon dioxide dynamic and static pressure tilting pad bearing system which comprises a tilting pad bearing with a supercritical carbon dioxide flow channel, a supercritical carbon dioxide air supply control loop and a temperature and pressure acquisition circuit. The tilting-pad bearing with the supercritical carbon dioxide runner comprises a bearing shell, a damper and a tile, the tile, the damper and the bearing shell are sequentially arranged from inside to outside, and the tile and the damper are fixed to the bearing shell. The damper is additionally arranged between the bearing bush and the bearing shell, the damping characteristic and stability of the bearing are effectively improved, the lubrication performance under an S-CO2 medium is improved through a dynamic and static pressure mixed lubrication mode, the defects of a static pressure bearing at a high rotating speed are overcome, the comprehensive service performance of the bearing is remarkably improved, and the service life of the bearing is prolonged. And good lubricating performance and bearing capacity can be kept in a wide rotating speed range.

Description

Technical Field

[0001] The present invention relates to the technical field of air bearings, and specifically to a wide-speed large-load supercritical carbon dioxide hydrostatic and hydrodynamic tilting pad bearing system. Background Art

[0002] In the technical field of mechanical bearings, with the wide application of supercritical carbon dioxide (S-CO2) as a circulating working fluid in multiple fields such as solar energy, nuclear energy, and waste heat utilization, higher requirements are imposed on the performance of bearings, and it can be used as a bearing lubricant with excellent performance. Supercritical carbon dioxide has the characteristics of high density, low viscosity, and strong fluidity. As a circulating working fluid, it can reduce compression power consumption and improve the cycle efficiency. However, when a supercritical carbon dioxide power unit is operating, especially under the requirements of high parameters and high performance, the bearing is required to meet the needs of its high DN value (shaft speed × bearing inner diameter) and high stability.

[0003] However, in actual use of the existing technology, traditional oil-lubricated bearings are prone to decomposition failure of the lubricating medium in a high-temperature environment and are difficult to adapt to the corrosive and low-viscosity characteristics of supercritical carbon dioxide;

[0004] Although gas bearings are suitable for high-speed scenarios, their load-carrying capacity is limited and they cannot meet the large-load requirements;

[0005] Hydrostatic bearings have excellent stability at low speeds, but the hydrodynamic effect is insufficient at high speeds;

[0006] Hydrodynamic bearings rely on the rotational speed to form a lubricating film and are prone to boundary friction at low speeds;

[0007] Hydrostatic and hydrodynamic hybrid bearings combine the advantages of both to a certain extent, but in a supercritical carbon dioxide medium, their dynamic response and load-carrying uniformity are still insufficient;

[0008] Tilting pad bearings can optimize the lubricating film distribution and improve stability through self-adaptive adjustment of the pads, but their application research in a supercritical carbon dioxide environment is not yet mature. Existing tilting pad structures are mostly designed for traditional lubricating media and do not fully consider the phase change characteristics, thermodynamic behavior of supercritical fluids, and their influence on the dynamic characteristics of bearing clearances, resulting in problems such as lubricating film rupture and local overheating under high-speed and heavy-load conditions. Summary of the Invention

[0009] The purpose of the present invention is to provide a wide-speed large-load supercritical carbon dioxide hydrostatic and hydrodynamic tilting pad bearing system to solve the problems that the load-carrying capacity and stability of bearings under S-CO2 medium are poor and cannot meet the application requirements of a wide speed range and large load-carrying capacity.

[0010] To achieve the above object, the present invention provides the following technical solution: a wide-speed and large-load supercritical carbon dioxide hydrostatic tilting pad bearing system, comprising a tilting pad bearing with a supercritical carbon dioxide flow channel, a supercritical carbon dioxide gas supply control circuit, and a temperature and pressure acquisition circuit;

[0011] The tilting pad bearing with a supercritical carbon dioxide flow channel includes a bearing housing, dampers, and pads. The pads, dampers, and bearing housing are arranged in sequence from the inside out. The pads and dampers are respectively fixed on the bearing housing. A plurality of static pressure supercritical carbon dioxide flow channels are evenly distributed on the bearing housing in the axial and circumferential directions. Air supply holes communicating with the static pressure supercritical carbon dioxide flow channels are formed in the inner wall of the pads, so that static pressure supercritical carbon dioxide supplies gas to the rotating shaft inside the pads through the static pressure supercritical carbon dioxide flow channels and the air supply holes;

[0012] The temperature and pressure acquisition circuit includes a pressure sensor and a temperature sensor arranged at one end of the pad corresponding to the air supply hole, and is used for acquiring the pressure and temperature load distributions of the gas film at different positions in the gap between the bearing housing and the rotating shaft during the rotation of the rotating shaft;

[0013] The supercritical carbon dioxide gas supply control circuit includes a gas source, a controller, and multiple groups of supercritical carbon dioxide gas supply regulating valves. The gas source is used to supply static pressure supercritical carbon dioxide to the inside of the static pressure supercritical carbon dioxide flow channels. The supercritical carbon dioxide gas supply regulating valves are arranged at the positions between the gas source and the corresponding static pressure supercritical carbon dioxide flow channels. The pressure sensor, the temperature sensor, and the supercritical carbon dioxide gas supply regulating valves are respectively electrically connected to the controller. The supercritical carbon dioxide gas supply regulating valves are installed at the positions between the output pipeline of the gas source and the static pressure supercritical carbon dioxide flow channels.

[0014] Preferably, the damper is a metal wire mesh.

[0015] Preferably, the number of the static pressure supercritical carbon dioxide flow channels is eight, and the eight static pressure supercritical carbon dioxide flow channels are divided into four groups. Each group of two static pressure supercritical carbon dioxide flow channels is evenly arranged in the middle of the pad along the axial direction.

[0016] Preferably, the number of the pressure sensors and the temperature sensors is the same as the number of the air supply holes.

[0017] Preferably, the controller adopts a microcontroller, and the gas source includes one of carbon dioxide and supercritical carbon dioxide.

[0018] Preferably, the controller is used to process and analyze the data of the gas film pressure and temperature load distribution at different positions of the gap between the bearing housing and the rotating shaft during the rotation of the rotating shaft, which are collected in real time by the pressure sensor and the temperature sensor, as well as the real-time rotational speed signal and vibration signal of the on-site motor, and calculate the corresponding control signals, so that the supercritical carbon dioxide supply regulating valve dynamically adjusts the supply pressure and flow rate of each static-pressure supercritical carbon dioxide flow channel and its corresponding air supply holes according to the instructions of the controller.

[0019] Preferably, the supercritical carbon dioxide supply regulating valve includes a pressure reducing valve, a separator, an electro-hydraulic proportional valve and a pilot pressure reducing valve, and the supercritical carbon dioxide supply regulating valve is used for multi-stage pressure regulation of each static-pressure supercritical carbon dioxide flow channel.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. By adding a damper between the bearing pad and the bearing housing, the damping characteristics and stability of the bearing are effectively improved. The hybrid hydrostatic and hydrodynamic lubrication method improves the lubrication performance under the S-CO2 medium, overcomes the defects of the hydrostatic bearing at high speeds, and significantly improves the comprehensive service performance of the bearing, enabling it to maintain good lubrication performance and load-carrying capacity within a wide speed range.

[0022] 2. At low speeds, the hydrostatic effect plays a dominant role. At high speeds, the hydrodynamic effect gradually increases and acts together with the hydrostatic pressure to maintain the stable suspension of the bearing. This hydrostatic-hydrodynamic switching and adjustment mechanism enables the bearing to adapt to the requirements of different speeds. At the same time, by intelligently adjusting the hydrostatic supply pressure, the present invention can flexibly adjust the stiffness and load-carrying capacity of the bearing, reduce the consumption of the external gas source, and achieve significant energy-saving effects. In addition, during high-speed operation, by adjusting the hydrostatic gas supply volume and flow rate and utilizing the cooling effect of supercritical carbon dioxide, the operating temperature of the bearing is effectively reduced, and the durability and stability of the bearing are improved. Brief Description of the Drawings

[0023] Figure 1 is a partial exploded view of the overall structure of the wide-speed and large-load supercritical carbon dioxide hybrid hydrostatic and hydrodynamic tilting pad bearing system of the present invention;

[0024] Figure 2 is a partial front cross-sectional view of the overall structure of the wide-speed and large-load supercritical carbon dioxide hybrid hydrostatic and hydrodynamic tilting pad bearing system of the present invention;

[0025] Figure 3 is a schematic diagram of the control loop of the circumferential static-pressure supercritical carbon dioxide flow channel of the wide-speed and large-load supercritical carbon dioxide hybrid hydrostatic and hydrodynamic tilting pad bearing system of the present invention;

[0026] Figure 4This is a schematic block diagram of the operation process of the wide-speed and large-load supercritical carbon dioxide hydrostatic and hydrodynamic tilting pad bearing system of the present invention.

[0027] In the figure: 1. Bearing housing; 2. Damper; 3. Air supply hole; 4. Hydrostatic supercritical carbon dioxide flow channel; 5. Pad; 6. Pressure sensor; 7. Temperature sensor; 8. Pressure reducing valve; 9. Separator; 10. Electro-hydraulic proportional valve; 11. Pilot pressure reducing valve. Specific embodiments

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] Please refer to Figures 1-4 , the present invention provides a technical solution: a wide-speed and large-load supercritical carbon dioxide hydrostatic and hydrodynamic tilting pad bearing system, including a tilting pad bearing with a supercritical carbon dioxide flow channel, a supercritical carbon dioxide gas supply control circuit, and a temperature and pressure acquisition circuit;

[0030] The tilting pad bearing with a supercritical carbon dioxide flow channel includes a bearing housing 1, a damper 2, and a pad 5. The pad 5, the damper 2, and the bearing housing 1 are arranged in sequence from the inside out and are in contact with each other. The pad 5 and the damper 2 are respectively fixed on the bearing housing 1. The damper 2 of the present invention is a wire mesh. A plurality of hydrostatic supercritical carbon dioxide flow channels 4 are distributed on the bearing housing 1 in the axial and circumferential directions. Corresponding air supply holes 3 are respectively provided on the pad 5 to communicate with the hydrostatic supercritical carbon dioxide flow channels 4, so that hydrostatic supercritical carbon dioxide supplies gas to the rotating shaft in the pad 5 through the corresponding groups of hydrostatic supercritical carbon dioxide flow channels 4 and air supply holes 3. The hydrostatic supercritical carbon dioxide flow channels 4 can be air supply small holes, throttle small holes, porous medium materials, or slit type, etc. The structural form is not limited, and there is no requirement for the number of flow channels. In this embodiment, the hydrostatic supercritical carbon dioxide flow channels 4 are as Figure 2 shown. The hydrostatic supercritical carbon dioxide flow channels 4 adopt a throttle small hole structure. The number of hydrostatic supercritical carbon dioxide flow channels 4 is eight, and the eight hydrostatic supercritical carbon dioxide flow channels 4 are divided into four groups, and each group of two hydrostatic supercritical carbon dioxide flow channels 4 is uniformly arranged in the middle of the pad 5 along the axial direction.

[0031] The temperature and pressure acquisition circuit includes a pressure sensor 6 and a temperature sensor 7. At one end of the tile 5 corresponding to the position of the air supply hole 3, a pressure sensor 6 and a temperature sensor 7 are installed. The pressure sensor 6 and the temperature sensor 7 are distributed on the circumferential and axial inner sides of the tile 5, and are used to collect the pressure and temperature load distributions of the air film at different positions in the gap between the bearing housing 1 and the rotating shaft during the rotation of the rotating shaft, as the input data for the dynamic and static pressure switching control.

[0032] The supercritical carbon dioxide gas supply control loop includes a gas source, a controller, and multiple groups of supercritical carbon dioxide gas supply regulating valves. The static pressure supercritical carbon dioxide flowing into the static pressure supercritical carbon dioxide flow channel 4 is supplied by an external gas source. The supercritical carbon dioxide gas supply regulating valve is arranged between the gas source and the corresponding static pressure supercritical carbon dioxide flow channel 4; during the rotation of the bearing, the controller processes and analyzes the data of the pressure and temperature load distributions of the air film at different positions in the gap between the bearing and the rotating shaft, the real-time rotational speed signal and vibration signal of the on-site motor collected by the pressure sensor 6 and the temperature sensor 7 in real time, calculates the corresponding control signal, and the supercritical carbon dioxide gas supply regulating valve dynamically adjusts the gas supply pressure and flow rate of each static pressure supercritical carbon dioxide flow channel 4 and its corresponding air supply hole 3 according to the instructions of the controller. The controller uses a common microcontroller without special requirements. The gas source uses carbon dioxide or other supercritical carbon dioxide, such as Figure 3 As shown, the pressure sensor 6, the temperature sensor 7, and the supercritical carbon dioxide gas supply regulating valve are respectively electrically connected to the controller. The supercritical carbon dioxide gas supply regulating valve is installed at the position between the output pipeline of the gas source and the static pressure supercritical carbon dioxide flow channel 4.

[0033] The supercritical carbon dioxide gas supply regulating valve is composed of a pressure reducing valve 8, a separator 9, an electro-hydraulic proportional valve 10, and a pilot pressure reducing valve 11. The supercritical carbon dioxide gas supply regulating valve is used for multi-stage pressure regulation of each static pressure supercritical carbon dioxide flow channel 4.

[0034] Working principle: As Figure 4 shown, the method for performing dynamic and static pressure switching regulation using the tilting pad bearing with a supercritical carbon dioxide flow channel of the present invention includes: low-speed static pressure dominance, high-speed dynamic pressure dominance, high-speed static pressure heat dissipation, and high-speed static pressure stiffness regulation;

[0035] During the operation of the bearing, its supporting pressure is:

[0036] P 总 = P 静 + P 动

[0037] In the formula, P 总 represents the total gravity of the rotor and external loads, that is, the bearing load; P 静 represents the bearing air buoyancy component caused by the static pressure effect inside the bearing; P动 represents the bearing aerostatic buoyancy component formed by the hydrodynamic effect during journal rotation;

[0038] Wherein,

[0039] Low-speed hydrostatic dominance: When the journal speed is lower than the takeoff speed, the supercritical carbon dioxide supply control loop supplies high-pressure and high-flow compressed supercritical carbon dioxide to the bearing through the hydrostatic supercritical carbon dioxide flow path 4 and the supply holes 3. Under the main action of the external hydrostatic pressure, the bearing is lifted by the gas film and separated from the rotating shaft, presenting a suspended state;

[0040] High-speed hydrodynamic dominance: As the journal speed increases, the pressure of the hydrodynamic gas film formed between the bearing and the journal increases. At this time, the supercritical carbon dioxide supply control loop gradually reduces the supply pressure of each hydrostatic supercritical carbon dioxide flow path 4 and the supply holes 3, so that the bearing remains suspended under the main action of the hydrodynamic pressure;

[0041] High-speed hydrostatic heat dissipation: When the journal speed reaches or exceeds the hydrodynamic takeoff speed, the hydrostatic pressure drops to a lower level; at this time, according to the bearing gas film temperature distribution detected by the temperature sensor 7, the supercritical carbon dioxide supply control loop adjusts the gas supply volume of each hydrostatic supercritical carbon dioxide flow path 4 and the supply holes 3, so that the supercritical carbon dioxide takes away part of the heat and plays a role in heat dissipation;

[0042] High-speed hydrostatic stiffness adjustment: At this time, in order to achieve the design stiffness and load-carrying capacity indicators of the bearing, according to the signals of the temperature sensor 7 and the pressure sensor 6 and the vibration signal, the supercritical carbon dioxide supply control loop dynamically adjusts the supply pressure and flow rate of each hydrostatic supercritical carbon dioxide flow path 4 and the supply holes 3, and adjusts the stiffness and load-carrying capacity of the bearing by enhancing or weakening the hydrostatic effect of the supercritical carbon dioxide.

[0043] Based on the tilting pad bearing, combined with the characteristics of the hydrostatic bearing, the present invention adds hydrostatic supercritical carbon dioxide flow paths 4 in the axial and circumferential directions of the tilting pad bearing to connect to the external gas source. Through the supercritical carbon dioxide supply control loop, the supply pressure and flow rate are intelligently adjusted, and the load is supported by the combined action of the hydrostatic and hydrodynamic effects of the supercritical carbon dioxide. At low speeds or zero speed, the external gas source outputs high-pressure and high-flow supercritical carbon dioxide through the supercritical carbon dioxide supply control system, and the bearing can remain suspended at low speeds by using the hydrostatic effect. As the speed increases, the dynamic pressure of the bearing increases, and the dependence on the hydrostatic gas source decreases. Therefore, the supercritical carbon dioxide supply control system will adaptively reduce the output pressure and flow rate of the hydrostatic gas supply system, reduce the consumption of the external gas source, and the small-flow supercritical carbon dioxide provided can effectively cool the bearing, improving the stability, durability and energy efficiency of the tilting pad bearing. In addition, the present invention can flexibly increase or decrease the stiffness and load-carrying capacity of the tilting pad bearing by intelligently adjusting the hydrostatic supply pressure.

[0044] In the present invention, a damper 2 made of wire mesh is added between the tile 5 and the bearing housing 1, increasing the damping coefficient of the bearing, improving the stability of the bearing, and combining the working characteristics of hydrodynamic bearings and hydrostatic bearings. During operation, the supporting pressure thereof is the sum of the hydrostatic pressure provided by an external gas source and the hydrodynamic pressure formed by its own rotation.

[0045] When the rotor speed is relatively low or zero, the external gas source outputs high-pressure and high-flow supercritical carbon dioxide through the supercritical carbon dioxide supply control circuit, and the bearing is separated from the rotating shaft mainly under the action of the hydrostatic effect.

[0046] As the rotor speed gradually increases, the hydrodynamic pressure of the bearing itself also gradually increases, reducing the dependence on the hydrostatic gas source. The supercritical carbon dioxide supply control circuit then adaptively reduces the pressure and flow rate of each air supply hole, reducing the consumption of the external gas source, and enabling the bearing to continue to maintain a suspended state relying on the supercritical carbon dioxide hydrostatic and hydrodynamic effects. At the same time, the small-flow supercritical carbon dioxide provided by the external gas source at this time can effectively cool the bearing.

[0047] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising", or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or device.

[0048] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A wide-speed large-load supercritical carbon dioxide hydrostatic and hydrodynamic tilting pad bearing system, characterized in that: It includes a tilting pad bearing with a supercritical carbon dioxide flow channel, a supercritical carbon dioxide supply control circuit, and a temperature and pressure acquisition circuit; The tilting pad bearing with a supercritical carbon dioxide flow channel includes a bearing housing (1), dampers (2), and pads (5). The pads (5), dampers (2), and bearing housing (1) are arranged in sequence from the inside out. The pads (5) and dampers (2) are respectively fixed on the bearing housing (1). A plurality of static pressure supercritical carbon dioxide flow channels (4) are evenly distributed on the bearing housing (1) in the axial and circumferential directions. Air supply holes (3) communicating with the static pressure supercritical carbon dioxide flow channels (4) are provided on the inner wall of the pads (5), so that static pressure supercritical carbon dioxide supplies air to the rotating shaft inside the pads (5) through the static pressure supercritical carbon dioxide flow channels (4) and the air supply holes (3); The temperature and pressure acquisition circuit includes a pressure sensor (6) and a temperature sensor (7) arranged at one end of the pad (5) corresponding to the air supply hole (3), and is used for acquiring the pressure and temperature load distributions of the air film at different positions of the gap between the bearing housing (1) and the rotating shaft during the rotation of the rotating shaft; The supercritical carbon dioxide supply control circuit includes a gas source, a controller, and multiple groups of supercritical carbon dioxide supply regulating valves. The gas source is used to supply static pressure supercritical carbon dioxide to the inside of the static pressure supercritical carbon dioxide flow channels (4). The supercritical carbon dioxide supply regulating valves are arranged at the positions between the gas source and the corresponding static pressure supercritical carbon dioxide flow channels (4). The pressure sensor (6), temperature sensor (7), and supercritical carbon dioxide supply regulating valves are respectively electrically connected to the controller. The supercritical carbon dioxide supply regulating valves are installed at the positions between the output pipeline of the gas source and the static pressure supercritical carbon dioxide flow channels (4).

2. The wide-speed-range and large-load-capacity supercritical carbon dioxide hydrostatic and hydrodynamic tilting pad bearing system according to claim 1, wherein: The damper (2) is a wire mesh.

3. The wide-speed large-load supercritical carbon dioxide hydrostatic and hydrodynamic tilting pad bearing system according to claim 1, characterized in that: The number of the static pressure supercritical carbon dioxide flow channels (4) is eight, and the eight static pressure supercritical carbon dioxide flow channels (4) are divided into four groups. Each group of two static pressure supercritical carbon dioxide flow channels (4) is evenly arranged axially in the middle of the pad (5).

4. The wide-speed-range and large-load-capacity supercritical carbon dioxide hydrostatic and hydrodynamic tilting pad bearing system according to claim 1, wherein: The number of the pressure sensors (6) and temperature sensors (7) is the same as the number of the air supply holes (3).

5. The wide-speed-range and large-load-capacity supercritical carbon dioxide hydrostatic and hydrodynamic tilting pad bearing system according to claim 1, characterized in that: The controller uses a microcontroller, and the gas source includes one of carbon dioxide and supercritical carbon dioxide.

6. The wide-speed large-load supercritical carbon dioxide hydrostatic and hydrodynamic tilting pad bearing system according to claim 1, characterized in that: The controller is used to process and analyze the data of the pressure and temperature load distributions of the air film at different positions of the gap between the bearing housing (1) and the rotating shaft, the real-time rotational speed signal and vibration signal of the on-site motor, which are collected by the pressure sensor (6) and temperature sensor (7) in real time during the rotation of the rotating shaft, and calculate the corresponding control signals, so that the supercritical carbon dioxide supply regulating valves dynamically adjust the air supply pressure and flow rate of each static pressure supercritical carbon dioxide flow channel (4) and its corresponding air supply hole (3) according to the instructions of the controller.

7. The tilting pad journal bearing system of supercritical carbon dioxide with wide speed range and large load capacity according to claim 1, wherein: The supercritical carbon dioxide supply regulating valve includes a pressure reducing valve (8), a separator (9), an electro-hydraulic proportional valve (10), and a pilot pressure reducing valve (11). The supercritical carbon dioxide supply regulating valve is used for multi-stage pressure regulation of each static pressure supercritical carbon dioxide flow channel (4).

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