A new type of thrust bearing structure for a hydroelectric generator

Abstract

The present application relates to vertical water turbine generator bearing technical field, specifically to a new type of water turbine generator thrust bearing structure, including support structure, thrust pad structure and lubricating oil system, support structure adopts spring bundle support structure, thrust pad structure is elastic metal fluoroplastic pad, lubricating oil system is low liquid level spray type external circulation lubricating oil system; Low liquid level spray type external circulation lubricating oil system includes external cooler, external circulation oil pump, auxiliary oil tank and oil injection pipe, cooler is communicated with bearing oil groove through pipeline, external circulation oil pump is arranged on the pipeline between cooler and auxiliary oil tank, auxiliary oil tank is arranged opposite to the working surface of thrust pad through oil injection pipe;In the unit operating state, the lubricating oil level in the bearing oil groove is lower than the pad surface of the thrust pad, which solves the problem that the existing vertical water turbine generator thrust bearing lacks collaborative optimization design, and it is difficult to simultaneously solve the problems of high pad temperature, high loss, oil mist pollution and complex installation.

Description

Technical Field

[0001] This invention relates to the field of technology, and in particular to a novel thrust bearing structure for a hydro-generator. Background Technology

[0002] The thrust bearing of a vertical hydro generator is a core component of the unit, primarily responsible for supporting the rotating parts and bearing the entire thrust load. Its performance directly determines the long-term safe and stable operation of the unit. Thrust bearings typically consist of three parts: a support structure, a thrust bearing pad structure, and a lubrication system. Current technologies have numerous design deficiencies in each component, leading to problems such as excessively high bearing temperature, high bearing wear, severe oil mist contamination, and cumbersome installation and adjustment during unit operation, thus restricting the unit's operating efficiency and service life.

[0003] In terms of support structure, domestic thrust bearings mainly adopt three forms: strut screw support, elastic oil tank support, and spring bundle support. Strut screw support is a rigid structure, which makes it difficult to level the surface of each bearing and adjust the stress during installation, resulting in a large amount of adjustment work and an inability to balance the thrust load of each bearing during operation. Elastic oil tank support can achieve automatic load balancing, but it has extremely high requirements for oil tank material and manufacturing process, resulting in high production costs and maintenance difficulties. Although traditional spring bundle support has the advantages of strong load-bearing capacity and low temperature rise, it is not designed in conjunction with suitable thrust bearings and lubrication systems, so its performance advantages are not fully utilized.

[0004] In terms of thrust bearing structure, the mainstream types are tungsten gold bearings and elastic metal fluoroplastic bearings (hereinafter referred to as plastic bearings): Tungsten gold bearings have a surface made of bearing lead-tin alloy, which has high hardness and high elastic modulus. During start-up and shutdown, the bearing surface is easily damaged due to oil film rupture. A high-pressure oil lifting system must be used, and the bearing surface needs to be scraped, making installation and maintenance complicated. Although plastic bearings have the advantages of not requiring high-pressure oil lifting and having lower bearing temperature, they are mostly used in combination with elastic oil tank supports in current applications, without combining with an optimized support structure to give full play to their self-adjusting and high load-bearing performance.

[0005] Regarding the lubrication system, the existing structure mainly consists of an internal circulation system built into the cooler and a conventional external circulation system, both of which are immersion lubrication. When the unit is running, the lubricating oil level is higher than the thrust bearing surface, and there is a serious oil churning phenomenon on the non-load-bearing surface. This not only generates a lot of oil churning losses and reduces the unit efficiency, but also generates a lot of oil mist due to the lubricating oil churning, causing oil accumulation in the machine pit, oil stains on the stator coils, and other pollution problems, while also increasing the bearing temperature rise.

[0006] In summary, the components of existing vertical hydro-generator thrust bearings lack synergistic optimization design, making it difficult to simultaneously solve technical problems such as high bearing temperature, high losses, oil mist pollution, and complex installation. There is an urgent need for an integrated, high-performance new thrust bearing structure to meet the requirements of efficient, safe, and stable operation of hydro-generator units. Summary of the Invention

[0007] The purpose of this invention is to provide a novel thrust bearing structure for hydro-generators, which solves the problems of lack of coordinated optimization design among the components of existing vertical hydro-generator thrust bearings, making it difficult to simultaneously address issues such as high bearing temperature, high losses, oil mist pollution, and complex installation.

[0008] To achieve the above objectives, this invention provides a novel thrust bearing structure for a hydro-generator, comprising a support structure, a thrust bearing structure, and a lubrication system. The support structure is characterized by a spring-bundle support structure, the thrust bearing structure is an elastic fluoroplastic metal bearing, and the lubrication system is a low-level spray-type external circulation lubrication system. The low-level spray-type external circulation lubrication system includes an external cooler, an external circulation oil pump, an auxiliary oil tank, and an oil spray pipe. The cooler is connected to the bearing oil sump via a pipeline, the external circulation oil pump is located on the pipeline between the cooler and the auxiliary oil tank, and the auxiliary oil tank is arranged opposite to the working surface of the thrust bearing via the oil spray pipe. During unit operation, the lubricating oil level in the bearing oil sump is lower than the surface of the thrust bearing.

[0009] The elastic element of the spring bundle support structure is a cylindrical helical spring. Multiple clusters of spring bundles with equal height and uniform stiffness are arranged in an array, and each cluster of spring bundles independently supports a thrust bearing. In addition to bearing the thrust load of the unit, the spring bundles also have the function of balancing the load of each thrust bearing and absorbing the vibration of the unit operation.

[0010] The spring bundle support structure is a floating support structure, and its resultant force point can be adaptively adjusted according to the load and linear velocity changes of the unit, adapting to various unit operating conditions such as low-speed heavy load and high-speed.

[0011] The elastic fluoroplastic metal tile has a non-metallic elastic composite fluoroplastic layer on its surface, the average thickness of which is 1.5 mm. The insulation resistance of the elastic fluoroplastic metal tile is greater than 50 MΩ (measured with a 1000V megohmmeter). The elastic fluoroplastic metal tile has no high-pressure oil chamber on its surface and does not require a high-pressure oil lifting system.

[0012] The working oil temperature range of the elastic fluoroplastic metal tile is 5-50℃. Under the same unit operating conditions, its tile temperature is about 20K lower than that of tungsten gold tile.

[0013] The working process of the low-level spray-type external circulation lubricating oil system is as follows: the external circulation oil pump extracts the hot oil from the bearing oil tank and delivers it to the external cooler for cooling. The cooled lubricating oil is delivered to the auxiliary oil tank and then sprayed precisely onto the working surface of the thrust bearing through the oil spray pipe to achieve lubrication. The lubricating oil only acts on the bearing surface of the thrust bearing, and there is no lubricating oil stirring contact on the non-bearing surface.

[0014] The low-level spray-type external circulation lubricating oil system eliminates oil churning losses on non-load-bearing surfaces through low-level design and spray lubrication method, while avoiding oil mist generated by lubricating oil churning during unit operation.

[0015] Among them, the axial height of the spring bundle support structure is the smallest among the conventional support structures of the thrust bearing of the vertical hydro generator, which can reduce the height of the bearing oil groove and the overall axial height of the unit.

[0016] The novel thrust bearing structure for a hydro-generator of the present invention, through the synergistic design of a spring bundle support structure, a plastic tile structure, and a low-level spray-type external circulation lubricating oil system, has the following significant advantages over the prior art: The bearing temperature is significantly reduced, and the operational safety is improved: the spring bundle support can balance the load of each thrust bearing and offset the thermal and mechanical deformation of the bearing. The plastic bearing itself has a lower bearing temperature. Combined with low-level spray lubrication, the heat generated by oil stirring is reduced. In actual applications, the average bearing temperature of the thrust bearing is reduced by about 8°C compared with the traditional structure, and the bearing temperature difference is controlled within 2°C, which meets the temperature requirements for long-term non-destructive operation of the plastic bearing and greatly improves the safety factor of bearing operation.

[0017] Bearing losses are significantly reduced and unit efficiency is improved: The low-level spray lubrication method eliminates oil churning losses on non-load-bearing surfaces. Compared with the traditional immersion lubrication structure, bearing losses are reduced by about 30% (in actual applications, losses are reduced from 394KW to 269KW, a reduction of 125KW), effectively improving the overall operating efficiency of the hydro-generator unit.

[0018] Completely eliminate oil mist pollution and improve the unit's operating environment: The bearing oil sump adopts a low liquid level design, and the lubricating oil only acts on the working surface of the thrust bearing. There is no lubricating oil stirring phenomenon, which solves the problem of oil mist generation in the unit from the root, avoids oil accumulation in the pit, stator coil oil contamination, etc., improves the overall cleanliness of the unit, and reduces the unit's maintenance costs.

[0019] Easy to install and maintain, with wide adaptability: the plastic tiles do not require scraping or a high-pressure oil jacking system, and there are no restrictions on cold or hot starts of the unit. During turning gear maintenance, only a small amount of clean turbine oil needs to be injected into the tile surface. The spring bundle support structure does not require high-precision leveling during installation and can adaptively balance the load. At the same time, this structure is not only suitable for low-speed heavy-duty bearings, but also for high-speed bearings. It can be applied to general hydro-generator units as well as pumped storage units, adapting to various operating conditions.

[0020] High load-bearing capacity and high operational stability: The spring bundle support structure has a large load-bearing capacity, and the plastic tile can automatically adjust the oil film pressure distribution and reduce the pressure peak. The deformation of the tile surface relative to the mirror plate is minimal. The combination of the two greatly improves the load-bearing capacity of the thrust bearing. At the same time, the spring bundle has the function of absorbing vibration, which effectively improves the stability of the unit operation and can basically eliminate faults such as "tile burning". Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0022] Figure 1 Schematic diagrams of three support structures for the thrust bearing of existing vertical hydro generators; Figure 2 This is a schematic diagram of the overall structure of the novel thrust bearing of the present invention; Figure 3 This is a distribution diagram of oil film thickness under rated operating conditions of the thrust bearing of the present invention, wherein (a) is a three-dimensional diagram of oil film thickness and (b) is a contour diagram of oil film thickness; Figure 4 The diagram shows the surface temperature distribution of the thrust bearing under rated operating conditions according to the present invention, where (a) is a three-dimensional diagram of the surface temperature and (b) is a contour map of the surface temperature. Detailed Implementation

[0023] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0024] The first embodiment of this application is as follows: Please see Figures 1 to 4 ,in, Figure 1 Schematic diagrams of three support structures for the thrust bearing of existing vertical hydro generators; Figure 2 This is a schematic diagram of the overall structure of the novel thrust bearing of the present invention; Figure 3 This is a distribution diagram of oil film thickness under rated operating conditions of the thrust bearing of the present invention, wherein (a) is a three-dimensional diagram of oil film thickness and (b) is a contour diagram of oil film thickness; Figure 4 The diagram shows the surface temperature distribution of the thrust bearing under rated operating conditions, where (a) is a three-dimensional diagram of the surface temperature and (b) is a contour map of the surface temperature. The present invention provides a novel thrust bearing structure for a hydro-generator, comprising: The aforementioned solution solves the problems of lack of coordinated optimization design among the components of the existing vertical hydro-generator thrust bearing, making it difficult to simultaneously address the issues of high surface temperature, high losses, oil mist pollution, and complex installation.

[0025] Regarding this specific implementation method: Structural design and assembly Assembly of the spring bundle support structure: Cylindrical helical springs are selected as elastic elements, and 10 clusters of spring bundles with equal height and uniform stiffness are fabricated and arranged in an array in the bearing oil groove. Each cluster of spring bundles independently supports an elastic metal fluoroplastic tile 2. This spring bundle support structure is a floating support, and its axial height is significantly reduced compared to the original elastic oil tank support, which simultaneously reduces the overall height of the bearing oil groove 3.

[0026] Assembly of elastic fluoroplastic metal roofing sheets: 10 elastic fluoroplastic metal roofing sheets are configured. The average thickness of the non-metallic elastic composite fluoroplastic layer on the surface of the sheet is 1.5mm. The insulation resistance is greater than 50MΩ as measured by a 1000V megohmmeter. There is no high-pressure oil chamber on the surface of the sheet. The original high-pressure oil jacking system of the unit is removed. At the same time, 20 guide bearing sheets are configured to work with the thrust sheets to achieve stable support for the unit.

[0027] Assembly of the low-level spray-type external circulation lubricating oil system: An external cooler is installed outside the bearing oil tank, and the external cooler is connected to the bearing oil tank through pipelines; an external circulation oil pump is installed on the pipeline between the external cooler and the auxiliary oil tank, and multiple oil spray pipes are connected to the oil outlet of the auxiliary oil tank. The oil outlet of the oil spray pipe is precisely aligned with the working surface of each thrust bearing to ensure that the lubricating oil can be sprayed evenly onto the working surface; the lubricating oil system is debugged to ensure that the lubricating oil level in the bearing oil tank is lower than the surface of the thrust bearing during unit operation, thus achieving the low-level design.

[0028] Unit operation and performance testing Oil film and bearing temperature testing: When the unit is running under rated conditions, the oil film thickness and bearing surface temperature of the thrust bearing are tested. The results show that the minimum oil film thickness of the thrust bearing is 49μm, which is greater than the 30μm required for long-term operation of the plastic bearing. The average bearing temperature is 42℃, which is less than the safe operating temperature of 55℃, consistent with the theoretical calculation value. The temperature difference between each bearing surface is controlled within 2℃, which is 8℃ lower than the bearing temperature before the modification, meeting the requirements for long-term non-destructive operation of the bearing.

[0029] Bearing loss detection: The bearing operating loss was calculated. The original immersion lubrication structure bearing loss was about 394KW. After adopting the low liquid level spray external circulation lubrication oil system of this invention, the bearing loss was only 269KW, a loss reduction of 32%, close to the design target of 30%, which greatly improved the unit operating efficiency.

[0030] Oil mist and cleanliness testing: After the unit has been running continuously for a period of time under rated operating conditions, an inspection was conducted inside the pit. No oil mist was generated in the pit, there was no oil accumulation on the lower frame, and there was no oil stain on the surface of the stator coils. This completely solved the oil mist pollution problem of the original unit, and the overall cleanliness of the unit was greatly improved.

[0031] Operational stability test: During the commissioning period after the unit was modified, there were no abnormal vibrations or noises in the thrust bearing. The spring bundle support structure effectively absorbed the vibration of the unit's operation, balanced the load of each thrust bearing, and no damage to the bearing surface occurred. The operational stability of the unit was significantly improved.

[0032] Installation and Maintenance Precautions When the elastic fluoroplastic metal tile 2 of the present invention is being inspected or rotated for axis alignment, there is no need to apply lard. Simply lift the rotor and inject a small amount of cleaning turbine oil onto the tile surface. Generally, after rotating the rotor 3 times, oil needs to be injected again onto the tile surface to ensure lubrication.

[0033] By using the plastic tile of this invention, the braking speed of the unit can be appropriately reduced (the specific value is customized according to the unit parameters), thereby reducing the wear of the brake pads and the contamination of the coil ends.

[0034] When the low-level spray-type external circulation lubricating oil system is running, the unobstructedness of the oil spray pipe should be checked regularly to ensure that the lubricating oil can be sprayed evenly onto the working surface of the thrust bearing. At the same time, the external cooler and external circulation oil pump should be maintained regularly to ensure the cooling effect and circulation efficiency of the lubricating oil.

[0035] The novel thrust bearing structure of the hydro-generator in this embodiment solves the problems of lack of coordinated optimization design among the components of the existing vertical hydro-generator thrust bearing, making it difficult to simultaneously address issues such as high bearing temperature, high losses, oil mist pollution, and complex installation.

[0036] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art can understand that all or part of the processes for implementing the above embodiments and equivalent changes made in accordance with the claims of this application still fall within the scope of this application.

Claims

1. A novel thrust bearing structure for a hydro-generator, comprising a support structure, a thrust bearing structure, and a lubrication system, characterized in that, The supporting structure adopts a spring bundle support structure, the thrust bearing structure is an elastic metal fluoroplastic bearing, and the lubricating oil system is a low-level spray-type external circulation lubricating oil system. The low-level spray-type external circulation lubricating oil system includes an external cooler, an external circulation oil pump, an auxiliary oil tank, and an oil spray pipe. The cooler is connected to the bearing oil sump through a pipeline, the external circulation oil pump is installed on the pipeline between the cooler and the auxiliary oil tank, and the auxiliary oil tank is arranged opposite to the working surface of the thrust bearing through the oil spray pipe. Under unit operating conditions, the lubricating oil level in the bearing oil sump is lower than the surface of the thrust bearing.

2. The novel thrust bearing structure for a hydro-generator as described in claim 1, characterized in that, The elastic element of the spring bundle support structure is a cylindrical helical spring. Multiple clusters of spring bundles with equal height and uniform stiffness are arranged in an array, and each cluster of spring bundles independently supports a thrust bearing. In addition to bearing the thrust load of the unit, the spring bundles also have the function of balancing the load of each thrust bearing and absorbing the vibration of the unit operation.

3. The novel thrust bearing structure for a hydro-generator as described in claim 2, characterized in that, The spring bundle support structure is a floating support structure, and its resultant force point can be adaptively adjusted according to the load and linear velocity changes of the unit, adapting to various unit operating conditions such as low-speed heavy load and high-speed.

4. The novel thrust bearing structure for a hydro-generator as described in claim 3, characterized in that, The elastic fluoroplastic metal tile has a non-metallic elastic composite fluoroplastic layer on its surface, the average thickness of which is 1.5 mm. The insulation resistance of the elastic fluoroplastic metal tile is greater than 50 MΩ (measured with a 1000V megohmmeter). The elastic fluoroplastic metal tile has no high-pressure oil chamber on its surface and does not require a high-pressure oil lifting system.

5. The novel thrust bearing structure for a hydro-generator as described in claim 4, characterized in that, The working oil temperature range of the elastic fluoroplastic metal tile is 5-50℃. Under the same unit operating conditions, its tile temperature is about 20K lower than that of tungsten gold tile.

6. The novel thrust bearing structure for a hydro-generator as described in claim 5, characterized in that, The working process of the low-level spray-type external circulation lubricating oil system is as follows: the external circulation oil pump extracts the hot oil from the bearing oil tank and delivers it to the external cooler for cooling. The cooled lubricating oil is delivered to the auxiliary oil tank and then precisely sprayed onto the working surface of the thrust bearing through the oil spray pipe to achieve lubrication. The lubricating oil only acts on the bearing surface of the thrust bearing, and there is no lubricating oil stirring contact on the non-bearing surface.

7. The novel thrust bearing structure for a hydro-generator as described in claim 6, characterized in that, The low-level spray-type external circulation lubricating oil system eliminates oil churning losses on non-load-bearing surfaces through low-level design and spray lubrication method, while avoiding oil mist generated by lubricating oil churning during unit operation.

8. The novel thrust bearing structure for a hydro-generator as described in claim 7, characterized in that, The axial height of the spring bundle support structure is the smallest among conventional support structures for thrust bearings of vertical hydro generators, which can reduce the height of the bearing oil groove and the overall axial height of the unit.

Images