A method and system for assessing the life of steam turbine blades

Abstract

This invention relates to a method and system for assessing the lifespan of steam turbine blades. The method includes the following steps: S1, acquiring vibration and rotational speed signals of the steam turbine blades; S2, obtaining the actual vibration value V1 of the steam turbine blades based on the vibration and rotational speed signals; S3, using the actual vibration value V1 as a fatigue reference for assessing the steam turbine blades to obtain the remaining lifespan y of the steam turbine blades. This invention effectively improves the reliability, stability, and accuracy of lifespan assessment for steam turbine blades, especially the last-stage blades of nuclear power steam turbines. It enables data collection and real-time lifespan assessment of steam turbine blades under any operating condition, while simplifying the process of assessing the lifespan of each turbine blade and improving assessment efficiency.

Description

Technical Field

[0001] This invention relates to the field of turbine blade technology, and more specifically, to a method and system for assessing the lifespan of turbine blades. Background Technology

[0002] Blades are key components of steam turbines, and among the most delicate and important. They withstand extremely harsh conditions, including high temperature, high pressure, enormous centrifugal force, steam excitation force, corrosion and vibration, and the combined effects of water droplet erosion in wet steam zones. In particular, the environmental conditions endured by the last-stage blades of a steam turbine are among the most demanding of all blades; therefore, the lifespan of the last-stage blades is almost equivalent to the lifespan of the entire steam turbine.

[0003] Currently, there are three main types of life assessment for turbine (especially nuclear power turbine) blades: The first type is inspection and replacement. According to the manufacturer's regulations, the blades should be replaced after the turbine has been running for more than 100,000 hours. However, in practice, the blades are basically found to be normal. Therefore, this blade inspection and replacement strategy is an over-maintenance. It not only increases the cost of blade inspection, but also makes it easier for unpredictable risks introduced by maintenance, such as equipment collisions and personnel injuries, to occur during the blade replacement process.

[0004] The second method is a fatigue damage assessment method for nuclear power turbine blades. By analyzing the fatigue damage of the blades, the lifespan of nuclear power turbine blades can be predicted. However, the current method of analyzing the fatigue damage of nuclear power turbine blades based on finite element analysis cannot accurately reflect the actual damage of the nuclear power turbine blades, and therefore cannot accurately calculate the lifespan of the blades.

[0005] The third approach is a further improvement on the second. It involves acquiring three-dimensional structural data of the blade, establishing a three-dimensional structural model, and performing simulation analysis on the model to obtain the location of the maximum elastic strain stress and the maximum alternating stress due to fatigue damage. Based on the maximum elastic alternating stress and blade material performance parameters, a Barkhausen noise calibration curve is developed. The Barkhausen noise signal of the corresponding blade is tested according to the location of the maximum alternating stress. Based on the Barkhausen calibration curve and noise signal, the fatigue damage of the nuclear power turbine blade is determined, thus predicting the fatigue damage life of the nuclear power turbine blade without damaging it. However, this method has limitations. The turbine has a large number of blades, and the stress on each blade varies, requiring a relatively large number of models. This results in numerous variables being introduced during the simulation, leading to lower accuracy. Furthermore, the real-time dynamic operation of the nuclear power turbine blades cannot be determined, especially given the high power output, large blade size, and low steam parameters of nuclear power turbines. During low-power operation, turbine vibration increases significantly, making this method unable to collect data on the operating status of turbine blades under different operating conditions and to provide real-time life assessment. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method and system for assessing the life of steam turbine blades.

[0007] The technical solution adopted by this invention to solve its technical problem is: to construct a method for evaluating the life of steam turbine blades, comprising the following steps:

[0008] S1. Acquire the vibration and rotational speed signals of the turbine blades;

[0009] S2. Obtain the actual vibration value V1 of the turbine blade based on the vibration signal and the rotation speed signal;

[0010] S3. The actual vibration value V1 is used as a fatigue reference for the turbine blade to evaluate and obtain the remaining life y of the turbine blade.

[0011] Furthermore, in the turbine blade life assessment method of the present invention, step S3 further includes:

[0012] The actual vibration value V1 is used as a fatigue reference for the turbine blade, and the remaining life y of the turbine blade is obtained by evaluating it according to the blade life assessment algorithm.

[0013] When V1 > V:

[0014]

[0015] When V1≤V:

[0016] y = AT

[0017] In the formula, A is the theoretical design life of the turbine blade, V is the theoretical vibration value of the turbine blade, T is the operating time of the turbine blade, and k is the corresponding empirical coefficient designed for different blades.

[0018] Furthermore, in the turbine blade life assessment method of the present invention, step S2 further includes:

[0019] The actual vibration value V1 of the turbine blade is obtained through a blade vibration algorithm:

[0020] V1=2πf*Δt*r

[0021] In the formula, f is the turbine rotational frequency obtained from the rotational speed signal, Δt is the time difference between two passes of the same blade by the vibration sensor obtained from the vibration signal, and r is the rotational radius of the turbine blade.

[0022] In addition, the present invention also provides a turbine blade life assessment system, including a blade vibration measurement module and a blade remaining life analysis module, wherein the blade vibration measurement module is connected to the blade remaining life analysis module.

[0023] The blade vibration measurement module is used to acquire and measure the actual vibration value V1 of the turbine blade based on the vibration signal and rotation speed signal of the turbine blade;

[0024] The blade remaining life analysis module is used to receive the actual vibration value V1 measured by the blade vibration measurement module, and use the actual vibration value V1 as a fatigue reference for the turbine blade to evaluate and analyze, so as to obtain the remaining life y of the turbine blade.

[0025] Furthermore, in the turbine blade life assessment system of the present invention, the blade remaining life analysis module performs assessment and analysis according to the blade life assessment algorithm to obtain the remaining life y of the turbine blade:

[0026] When V1 > V:

[0027]

[0028] When V1≤V:

[0029] y = AT

[0030] In the formula, A is the theoretical design life of the turbine blade, V is the theoretical vibration value of the turbine blade, T is the operating time of the turbine blade, and k is the corresponding empirical coefficient designed for different blades.

[0031] Furthermore, in the turbine blade life assessment system described in this invention, the blade vibration measurement module obtains the actual vibration value V1 of the turbine blade according to the blade vibration algorithm:

[0032] V1=2πf*Δt*r

[0033] In the formula, f is the turbine rotational frequency obtained from the rotational speed signal, Δt is the time difference between two passes of the same blade by the vibration sensor obtained from the vibration signal, and r is the rotational radius of the turbine blade.

[0034] Furthermore, in the turbine blade life assessment system described in this invention, the blade vibration measurement module includes a vibration sensor, a speed sensor, a signal acquisition unit, and a blade vibration calculation unit; the signal acquisition unit is connected to the vibration sensor, the speed sensor, and the blade vibration calculation unit.

[0035] The vibration sensor is used to acquire the vibration simulation signal of the turbine blade; the speed sensor is used to acquire the speed simulation signal of the turbine blade; the signal acquisition unit is used to sample the vibration simulation signal and the speed simulation signal at high speed to obtain the vibration digital signal and the speed digital signal; the blade vibration calculation unit is used to obtain the actual vibration value V1 of the turbine blade based on the vibration digital signal and the speed digital signal, and transmit the actual vibration value V1 to the blade remaining life analysis module.

[0036] Furthermore, in the turbine blade life assessment system of the present invention, the signal acquisition unit includes a first signal acquisition unit and a second signal acquisition unit; the first signal acquisition unit is connected to the vibration sensor, and the second signal acquisition unit is connected to the speed sensor;

[0037] The first signal acquisition unit is used to obtain the vibration digital signal by high-speed sampling of the vibration analog signal, and the second signal acquisition unit is used to obtain the rotational speed digital signal by high-speed sampling of the rotational speed analog signal.

[0038] Furthermore, in the turbine blade life assessment system described in this invention, the turbine is a nuclear power turbine.

[0039] Furthermore, in the turbine blade life assessment system described in this invention, the turbine blade is the last stage blade of the nuclear power turbine.

[0040] The turbine blade life assessment method and system of the present invention have the following advantages:

[0041] This invention can effectively improve the reliability, stability and accuracy of turbine blade life assessment. It can collect data and conduct real-time life assessment of turbine blade operating status under any operating conditions. At the same time, it simplifies the process of life assessment for each turbine blade and improves assessment efficiency. Attached Figure Description

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0043] Figure 1 This is a flowchart of the turbine blade life assessment method provided in the embodiments of the present invention;

[0044] Figure 2 This is a schematic diagram of the turbine blade life assessment system provided in an embodiment of the present invention;

[0045] Figure 3 This is a schematic diagram of the turbine blade life assessment system provided in an embodiment of the present invention;

[0046] Figure 4 This is a schematic diagram of the turbine blade life assessment system provided in an embodiment of the present invention. Detailed Implementation

[0047] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0048] In a preferred embodiment, reference Figure 1 The turbine blade life assessment method implemented in this paper includes the following steps:

[0049] S1. Acquire the vibration and rotational speed signals of the turbine blades. Specifically, the vibration signal of the turbine blades includes the simulated vibration signal of the blades collected by the sensor and the digital vibration signal sampled at high speed by the signal acquisition unit; similarly, the rotational speed signal of the turbine blades also includes the simulated rotational speed signal collected by the sensor and the digital rotational speed signal sampled at high speed by the signal acquisition unit.

[0050] S2. Obtain the actual vibration value V1 of the turbine blade based on the vibration signal and speed signal. Specifically, the blade vibration algorithm can measure the actual vibration value V1 of the blade based on the vibration signal and speed signal.

[0051] S3. Using the actual vibration value V1 as a reference for the fatigue of the turbine blade, the remaining life of the turbine blade is evaluated using the blade remaining life algorithm to obtain the remaining life y of the turbine blade.

[0052] Optionally, the life assessment method of this embodiment can be applied to various steam turbines, such as thermal power steam turbines, and can especially focus on the remaining life assessment of the last stage blades of nuclear power steam turbines.

[0053] This embodiment effectively improves the reliability, stability, and accuracy of turbine blade life assessment, enabling data collection and real-time life assessment of turbine blade operating status under any operating condition. It also simplifies the process of assessing the life of each turbine blade, improving assessment efficiency.

[0054] In some embodiments of the turbine blade life assessment method, step S3 further includes:

[0055] The actual vibration value V1 is used as a reference for the fatigue of the turbine blade, and the remaining life y of the turbine blade is obtained by evaluating it according to the blade life assessment algorithm.

[0056] When V1 > V:

[0057]

[0058] When V1≤V:

[0059] y = AT

[0060] In the formula, A represents the theoretical design life of the turbine blade, V represents the theoretical vibration value of the turbine blade, T represents the operating time of the turbine blade, and k represents the corresponding empirical coefficient designed for different blades. Optionally, the remaining life y is expressed in hours.

[0061] In this embodiment, the blade life assessment algorithm effectively improves the reliability, stability, and accuracy of turbine blade life assessment, enabling data collection and real-time life assessment of turbine blade operating status under any operating condition. It also simplifies the process of assessing the life of each turbine blade, thus improving assessment efficiency.

[0062] In some embodiments of the turbine blade life assessment method, step S2 further includes:

[0063] The actual vibration value V1 of the turbine blade is obtained through a blade vibration algorithm:

[0064] V1=2πf*Δt*r

[0065] In the formula, f is the turbine rotational frequency obtained from the rotational speed signal, Δt is the time difference between two passes of the same blade by the vibration sensor obtained from the vibration signal, and r is the rotational radius of the turbine blade. Specifically, the same blade can be any blade of the turbine or the last stage blade of the turbine.

[0066] In this embodiment, the blade vibration algorithm can accurately measure the actual vibration value of the turbine blade, which is beneficial for the remaining life assessment algorithm to obtain a more stable and reliable remaining life of the turbine blade.

[0067] In another preferred embodiment, reference Figure 2 The turbine blade life assessment system of this embodiment includes a blade vibration measurement module and a blade remaining life analysis module, with the blade vibration measurement module connected to the blade remaining life analysis module. Preferably, the turbine in this embodiment can be, but is not limited to, a nuclear power turbine, and the turbine blades can be, but are not limited to, the last-stage blades of a nuclear power turbine.

[0068] The blade vibration measurement module is used to acquire and measure the actual vibration value V1 of the turbine blade based on the vibration signal and rotational speed signal of the turbine blade.

[0069] The blade remaining life analysis module is used to receive the actual vibration value V1 measured by the blade vibration measurement module, and use the actual vibration value V1 as a fatigue reference for the turbine blade to evaluate and analyze, so as to obtain the remaining life y of the turbine blade.

[0070] This embodiment effectively improves the reliability, stability, and accuracy of turbine blade life assessment, enabling data collection and real-time life assessment of turbine blade operating status under any operating condition. It also simplifies the process of assessing the life of each turbine blade, improving assessment efficiency.

[0071] In some embodiments of the turbine blade life assessment system, the blade remaining life analysis module performs an assessment and analysis based on the blade life assessment algorithm to obtain the remaining life y of the turbine blade:

[0072] When V1 > V:

[0073]

[0074] When V1≤V:

[0075] y = AT

[0076] In the formula, A represents the theoretical design life of the turbine blade, V represents the theoretical vibration value of the turbine blade, T represents the operating time of the turbine blade, and k represents the corresponding empirical coefficient designed for different blades. Optionally, the remaining life y is expressed in hours.

[0077] In this embodiment, the blade remaining life analysis module utilizes a blade life assessment algorithm to evaluate the remaining life of each turbine blade, especially the last-stage blade. This effectively improves the reliability, stability, and accuracy of turbine blade life assessment, enabling data collection and real-time life assessment of turbine blade operating conditions under any circumstances. Simultaneously, it simplifies the process of assessing the life of each turbine blade, improving assessment efficiency.

[0078] In some embodiments of the turbine blade life assessment system, the blade vibration measurement module obtains the actual vibration value V1 of the turbine blade based on the blade vibration algorithm.

[0079] V1=2πf*Δt*r

[0080] In the formula, f is the turbine rotational frequency obtained from the rotational speed signal, Δt is the time difference between two passes of the same blade by the vibration sensor obtained from the vibration signal, and r is the rotational radius of the turbine blade. Specifically, the same blade can be any blade of the turbine or the last stage blade of the turbine.

[0081] In this embodiment, the blade vibration measurement module can accurately measure the actual vibration value of the turbine blade using the blade vibration algorithm, which is beneficial for the remaining life assessment algorithm to obtain a more stable and reliable remaining life of the turbine blade.

[0082] In some embodiments of the turbine blade life assessment system, reference Figure 3The blade vibration measurement module includes a vibration sensor, a speed sensor, a signal acquisition unit, and a blade vibration calculation unit. The signal acquisition unit connects the vibration sensor, the speed sensor, and the blade vibration calculation unit.

[0083] Vibration sensors are used to acquire simulated vibration signals of the turbine blades. Speed ​​sensors are used to acquire simulated rotational speed signals of the turbine blades. A signal acquisition unit performs high-speed sampling of the simulated vibration and rotational speed signals to obtain digital vibration and digital rotational speed signals. A blade vibration calculation unit calculates the actual vibration value V1 of the turbine blade based on the digital vibration and rotational speed signals and transmits the actual vibration value V1 to the blade remaining life analysis module. Optionally, the blade vibration calculation unit can also store the calculated data.

[0084] Specifically, the signal acquisition unit can further obtain the time difference between the turbine blades passing the vibration sensor and the turbine's rotational speed frequency based on the acquired signals. Alternatively, the sensor can be, but is not limited to, a magnetoresistive blade clearance sensor, an eddy current sensor, an electrodynamic sensor, a capacitive sensor, etc.

[0085] In this embodiment, the system provides feedback on the lifespan of turbine blades by monitoring their real-time vibration values. This results in more accurate and reliable data. Furthermore, the system allows for adjustments to algorithm coefficients based on long-term data, further enhancing the reliability, stability, and accuracy of turbine blade lifespan assessment. It enables data collection and real-time lifespan assessment of turbine blades under any operating condition. Simultaneously, it simplifies the lifespan assessment process for each turbine blade, improving assessment efficiency.

[0086] In some embodiments of the turbine blade life assessment system, reference Figure 4 The signal acquisition unit includes a first signal acquisition unit and a second signal acquisition unit. The first signal acquisition unit is connected to a vibration sensor, and the second signal acquisition unit is connected to a speed sensor.

[0087] The first signal acquisition unit is used to obtain a digital vibration signal by high-speed sampling of the simulated vibration signal, and the second signal acquisition unit is used to obtain a digital rotational speed signal by high-speed sampling of the simulated rotational speed signal. Preferably, the first signal acquisition unit can use a 24-bit high-precision AD chip to sample the simulated vibration signal of the turbine blade at a sampling rate of 240kbps; the second signal acquisition unit includes a dedicated hardware circuit for rotational speed and a high-precision AD chip, and can also sample the rotational speed signal of the turbine blade at a sampling rate of 240kbps. It should be noted that the sampling rate and the accuracy of the AD chip can be selected or set according to the specific requirements of the turbine and the system.

[0088] In this embodiment, the system can effectively improve the reliability, stability and accuracy of life assessment of turbine blades, especially the last stage blades of nuclear power turbines, and can collect data and conduct real-time life assessment of turbine blade operating status under any operating conditions.

[0089] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0090] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0091] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0092] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They do not limit the scope of protection of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for evaluating the life of a steam turbine blade, characterized in that, It includes the following steps: S1. Obtain the vibration signal and rotational speed signal of the steam turbine blade; S2. Obtain the actual vibration value V1 of the steam turbine blade based on the vibration signal and the rotational speed signal; S3. Evaluate the actual vibration value V1 as the reference for the fatigue degree of the steam turbine blade to obtain the remaining life y of the steam turbine blade; The step S2 further includes: Obtain the actual vibration value V1 of the steam turbine blade through the blade vibration algorithm: In the formula, f is the rotational speed frequency of the steam turbine obtained according to the rotational speed signal, △t is the time difference between the same blade passing through the vibration sensor twice obtained according to the vibration signal, and r is the rotational radius of the steam turbine blade; The step S3 further includes: Take the actual vibration value V1 as the reference for the fatigue degree of the steam turbine blade and evaluate it according to the blade life evaluation algorithm to obtain the remaining life y of the steam turbine blade: When V1 > V: When V1 ≤ V: In the formula, A is the theoretical design life duration of the steam turbine blade, V is the theoretical vibration value of the steam turbine blade, T is the already-operated duration of the steam turbine blade, and k is the corresponding empirical coefficient designed for different blades.

2. A steam turbine blade life assessment system, characterized in that, It includes a blade vibration measurement module and a blade remaining life analysis module, and the blade vibration measurement module is connected to the blade remaining life analysis module; The blade vibration measurement module is used to obtain and measure the actual vibration value V1 of the steam turbine blade based on the vibration signal and the rotational speed signal of the steam turbine blade; The blade remaining life analysis module is used to receive the actual vibration value V1 measured by the blade vibration measurement module and evaluate and analyze the actual vibration value V1 as the reference for the fatigue degree of the steam turbine blade to obtain the remaining life y of the steam turbine blade; The blade vibration measurement module obtains the actual vibration value V1 of the steam turbine blade through the blade vibration algorithm: In the formula, f is the rotational speed frequency of the steam turbine obtained according to the rotational speed signal, △t is the time difference between the same blade passing through the vibration sensor twice obtained according to the vibration signal, and r is the rotational radius of the steam turbine blade; The blade remaining life analysis module evaluates and analyzes according to the blade life evaluation algorithm to obtain the remaining life y of the steam turbine blade: When V1 > V: When V1 ≤ V: In the formula, A is the theoretical design life duration of the steam turbine blade, V is the theoretical vibration value of the steam turbine blade, T is the already-operated duration of the steam turbine blade, and k is the corresponding empirical coefficient designed for different blades.

3. The steam turbine blade life assessment system according to claim 2, wherein The blade vibration measurement module includes a vibration sensor, a rotational speed sensor, a signal acquisition unit, and a blade vibration calculation unit; the signal acquisition unit is connected to the vibration sensor, the rotational speed sensor, and the blade vibration calculation unit; The vibration sensor is used to obtain the vibration analog signal of the steam turbine blade; the rotational speed sensor is used to obtain the rotational speed analog signal of the steam turbine blade; the signal acquisition unit is used to perform high-speed sampling on the vibration analog signal and the rotational speed analog signal to obtain a vibration digital signal and a rotational speed digital signal; the blade vibration calculation unit is used to obtain the actual vibration value V1 of the steam turbine blade according to the vibration digital signal and the rotational speed digital signal, and transmit the actual vibration value V1 to the blade remaining life analysis module.

4. The steam turbine blade life assessment system according to claim 3, wherein The signal acquisition unit includes a first signal acquisition unit and a second signal acquisition unit; the first signal acquisition unit is connected to the vibration sensor, and the second signal acquisition unit is connected to the rotational speed sensor; The first signal acquisition unit is used to perform high-speed sampling on the vibration analog signal to obtain the vibration digital signal, and the second signal acquisition unit is used to perform high-speed sampling on the rotational speed analog signal to obtain the rotational speed digital signal.

5. The steam turbine blade life assessment system according to claim 2, wherein The steam turbine is a nuclear power steam turbine.

6. The steam turbine blade life assessment system according to claim 5, wherein The steam turbine blade is the last-stage blade of the nuclear power steam turbine.

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