A method and system for treating vibration of the last stage blades of a steam turbine under low load conditions

Abstract

This application discloses a method and system for handling the vibration of the last-stage blades of a steam turbine under low-load conditions. The method includes: real-time monitoring of steam turbine operating parameters and last-stage blade vibration parameters to determine if the steam turbine is under low-load conditions; when a low-load vibration risk condition is identified, a dual-path vibration suppression strategy is activated, adjusting the steam flow field in the last-stage flow region through steam compensation and suppressing blade vibration response through a damping enhancement structure; continuous monitoring of vibration parameters; when the blade vibration amplitude drops below a preset safety threshold and the aerodynamic damping Δ≥0, the dual-path vibration suppression strategy is stopped, and normal operation is restored; if the vibration parameters do not meet the standards, the steam compensation parameters and the damping structure's effectiveness are adjusted until the safety operation requirements are met; by accurately setting the criteria for determining low-load vibration risk conditions, vibration risks can be quickly identified, avoiding intervention delays.

Description

Technical Field

[0001] This invention relates to the field of boiler operation control technology, specifically to a method and system for handling vibration of the last stage blades of a steam turbine under low load conditions. Background Technology

[0002] As a core power source in energy sectors such as thermal power generation and nuclear power generation, the operational stability of steam turbines directly determines the safety and efficiency of the entire power generation system. The last-stage blades, as a key component of the steam turbine's flow path, withstand the impact of high-temperature, high-pressure steam and the enormous centrifugal force generated by high-speed rotation, making them one of the components most prone to vibration failure during steam turbine operation.

[0003] In actual operation, steam turbines often face low-load conditions (such as grid load adjustments, unit start-up and shutdown, and off-peak operation). Under these conditions, the turbine load is less than 50% of the rated load, resulting in a significant decrease in the final-stage steam flow rate and an increase in steam back pressure. This leads to severe airflow separation, eddies, blowout phenomena, and steam backflow problems in the final-stage flow path, ultimately causing severe vibration of the final-stage blades. This vibration under low-load conditions is a complex form of vibration coupled with airflow excitation and structural vibration. If this state persists for a long time, it can cause excessive dynamic stress on the blades, leading to fatigue cracks, accelerated wear, and in severe cases, even blade breakage, resulting in turbine shutdown, significant economic losses, and safety hazards.

[0004] Currently, existing technologies for treating vibration in the last stage blades of steam turbines are mainly designed for rated load or high load conditions, with limited effectiveness in suppressing vibration under low load conditions. Some existing solutions employ a single steam flow adjustment method, which is insufficient to completely resolve eddy current and steam backflow issues under low loads, resulting in poor vibration suppression stability. Other solutions merely optimize the blade structure to increase damping, failing to eliminate the root causes of airflow-induced vibration, and are difficult and costly to modify, with poor adaptability. Furthermore, existing monitoring and control systems lack accurate assessment of low-load vibration risk conditions, often intervening only after vibration exceeds limits, exhibiting significant lag and failing to achieve early vibration suppression and closed-loop control. Therefore, developing a method and system for treating vibration in the last stage blades of steam turbines that can accurately adapt to low-load conditions, provide stable suppression, has a simple structure, and is cost-effective has become an urgent technical challenge. Summary of the Invention

[0005] The purpose of this invention is to propose a method and system for treating the vibration of the last stage blades of a steam turbine under low load conditions in order to solve the problems mentioned in the background art.

[0006] To achieve the aforementioned objectives, the first technical solution adopted by this invention is: a method for treating vibration of the last-stage blades of a steam turbine under low-load conditions, comprising the following steps: Step 1: Monitor the turbine operating parameters and the vibration parameters of the last stage blades in real time. The operating parameters include turbine load, last stage steam back pressure, and steam flow rate. The vibration parameters include blade vibration frequency, vibration amplitude, and aerodynamic damping Δ. Step 2: Determine whether the steam turbine is under low load conditions. When the steam turbine load is less than 50% of the rated load, and the back pressure of the last stage steam rises to more than 15 kPa and the steam flow rate is in the low flow range, it is determined to be a low load vibration risk condition. Step 3: When the low-load vibration risk condition is determined, the dual-path vibration suppression strategy is activated. The steam flow field in the final stage flow region is adjusted by steam compensation, and the blade vibration response is suppressed by the damping enhancement structure. Step 4: Continuously monitor vibration parameters. When the blade vibration amplitude drops below the preset safety threshold and the aerodynamic damping Δ≥0, stop the dual-path vibration suppression strategy and restore normal operation. If the vibration parameters do not meet the standards, adjust the steam compensation parameters and the damping structure intensity until the safety operation requirements are met.

[0007] Furthermore, in step 1, the vibration parameters are acquired in real time by a laser vibrometer with a sampling rate of not less than 10kHz. The operating parameters are acquired synchronously by a pressure sensor and a flow sensor with a data acquisition duration of not less than 60s / set. After acquisition, the vibration data is filtered and preprocessed with a filter cutoff frequency of 200Hz.

[0008] Furthermore, in step 3, the steam compensation adjustment specifically involves: introducing external steam into the root of the last stage stationary blade and the moving blade through multiple hollow steam guide rods. Multiple jet holes are opened on the side of the steam guide rods near the closed end. The external steam forms a positive airflow by utilizing the pressure difference inside and outside the turbine, thereby changing the steam flow rate, velocity distribution and pressure in the last stage flow area, reducing eddy current generation, suppressing the blow-by phenomenon and preventing steam backflow, and reducing the airflow excitation force.

[0009] Furthermore, the steam guide rod is connected to the turbine cylinder through a fixing component. The closed end of the steam guide rod is close to the root of the stationary blade and the moving blade. The diameter of the jet hole is set according to the size of the last stage blade and the steam flow requirement. The steam parameters provided by the external steam source are matched with the steam parameters of the last stage of the turbine to avoid secondary vibration caused by sudden changes in steam parameters.

[0010] Further, in step 3, the damping enhancement structure specifically suppresses the vibration by generating a dry friction effect through the dry friction damping blocks on both sides of the blade crown, consuming the blade vibration energy, increasing the blade damping, and reducing the blade vibration response and dynamic stress; the dry friction damping block is a triangular structure, set at a distance of 0.2-0.25L from the top of the blade crown, where L is the length of the intermediate connecting body of the blade, and the thickness of the damping block is h=(1 / 2)Hsinθ, where H is the thickness of the blade root and θ is the torsion angle of the intermediate connecting body.

[0011] Furthermore, the intermediate connecting body between the dry friction damping block and the blade, the blade root, and the blade crown are machined from high-strength corrosion-resistant steel in one piece. Both the damping block and the blade root are provided with rounded chamfers with the same chamfer radius to avoid stress concentration.

[0012] Furthermore, in step 4, the preset safety threshold is a vibration amplitude ≤ 0.5 mm and a pneumatic damping Δ ≥ 0. If the vibration parameters still do not meet the standard after 3 adjustments, an alarm signal is issued, and the turbine load reduction or shutdown protection mechanism is triggered.

[0013] To achieve the above-mentioned objectives, the second technical solution adopted by the present invention is: a flue gas treatment system for achieving emission standards under low load conditions, comprising a processor, a memory, and at least one program, wherein the program is stored in the memory and configured to be executed by the processor, and the program includes instructions for executing a method for treating the vibration of the last stage blades of a steam turbine under low load conditions.

[0014] Due to the application of the above-mentioned technical solution, the present invention has the following advantages compared with the prior art: 1. This invention can quickly identify vibration risks and avoid intervention delays by precisely setting the judgment criteria for low-load vibration risk conditions (load is less than 50% of rated load, the back pressure of the last stage steam increases by 15 kPa or more, and the steam flow rate is in the low flow range). At the same time, it adopts a dual-path vibration suppression strategy of steam compensation and damping enhancement. It not only adjusts the steam flow field in the last stage flow area from the source to eliminate airflow excitation causes such as eddies, blasting and steam backflow, but also consumes the blade vibration energy through the damping enhancement structure. The dual action achieves efficient vibration suppression. Compared with a single suppression scheme, the vibration suppression stability is improved by more than 30%, which can effectively control the blade vibration amplitude within the safe threshold.

[0015] 2. The steam compensation unit adopts a structure in which a hollow steam guide rod is used in conjunction with an external steam source. This eliminates the need for significant modifications to the main structure of the turbine's last-stage blades. The steam guide rod is connected to the cylinder via a fixing component, making installation convenient. The damping enhancement unit uses a dry friction damping block machined integrally with the blades. This eliminates the need for additional complex damping mechanisms, resulting in lower processing difficulty and controllable costs. Compared to existing structural modification schemes, this reduces modification costs by more than 40%, and requires no additional energy consumption during operation. It is suitable for upgrading and modifying various existing steam turbines.

[0016] 3. This invention uses a monitoring module to collect operating parameters and vibration parameters in real time, a judgment module to accurately determine the operating condition, and a feedback adjustment module to adjust the suppression strategy in real time based on the vibration parameters, forming a closed-loop control system of "monitoring-judgment-suppression-feedback-adjustment". This system can track vibration changes in real time and avoid vibration rebound. At the same time, an alarm module and a protection module are added. When the vibration parameters fail to meet the standard after multiple adjustments, an alarm is issued in time and a shutdown protection is triggered. This effectively avoids serious failures such as fatigue cracks and fractures of the blades due to excessive vibration, significantly improves the safety and reliability of turbine operation, and reduces downtime losses.

[0017] 4. The steam compensation parameters and damping block dimensions of this invention can be flexibly adjusted according to the dimensions and operating parameters of the last-stage blades of different turbine models. The jet orifice diameter, damping block installation position and thickness can be adapted accordingly. There is no need to design a separate scheme for different turbine models. It is suitable for vibration treatment of the last-stage blades of various subcritical and supercritical turbines and has a wide range of applications.

[0018] 5. The monitoring module uses a high-precision laser vibration meter, pressure sensor, and flow sensor, in conjunction with an NI DAQmx acquisition card. The vibration parameter sampling rate is no less than 10kHz and the accuracy is no less than 0.01mm. The operating parameter acquisition response is rapid. At the same time, the vibration data is filtered and preprocessed to effectively remove interference signals and ensure the accuracy of the acquired data, providing reliable data support for operating condition judgment and vibration suppression strategy adjustment. Attached Figure Description

[0019] Figure 1 The flowchart of the method for treating the vibration of the last stage blades of a steam turbine under low load conditions provided by an embodiment of the present invention is shown. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0021] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or system that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or systems.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] like Figure 1 As shown in the figure, this embodiment of the invention provides a method for treating vibration of the last stage blades of a steam turbine under low load conditions, including the following steps: Step 1: Monitor the turbine operating parameters and the vibration parameters of the last stage blades in real time. The operating parameters include turbine load, last stage steam back pressure, and steam flow rate. The vibration parameters include blade vibration frequency, vibration amplitude, and aerodynamic damping Δ. Step 2: Determine whether the steam turbine is under low load conditions. When the steam turbine load is less than 50% of the rated load, and the back pressure of the last stage steam rises to more than 15 kPa and the steam flow rate is in the low flow range, it is determined to be a low load vibration risk condition. Step 3: When the low-load vibration risk condition is determined, the dual-path vibration suppression strategy is activated. The steam flow field in the final stage flow region is adjusted by steam compensation, and the blade vibration response is suppressed by the damping enhancement structure. Step 4: Continuously monitor vibration parameters. When the blade vibration amplitude drops below the preset safety threshold and the aerodynamic damping Δ≥0, stop the dual-path vibration suppression strategy and restore normal operation. If the vibration parameters do not meet the standards, adjust the steam compensation parameters and the damping structure intensity until the safety operation requirements are met.

[0024] According to an embodiment of the present invention, in step 1, the vibration parameters are collected in real time by a laser vibrometer with a sampling rate of not less than 10kHz, and the operating parameters are collected synchronously by a pressure sensor and a flow sensor with a data collection duration of not less than 60s / set. After collection, the vibration data is filtered and preprocessed with a filter cutoff frequency of 200Hz.

[0025] According to an embodiment of the present invention, in step 3, the steam compensation adjustment specifically involves: introducing external steam into the root of the last stage stationary blade and the moving blade through multiple hollow steam guide rods; multiple jet holes are provided on the side of the steam guide rods near the closed end; the external steam is made to form a positive airflow by utilizing the pressure difference between the inside and outside of the turbine; the steam flow rate, velocity distribution and pressure in the last stage flow area are changed; the generation of eddies is reduced; the blow-by phenomenon is suppressed; and steam backflow is prevented; thus reducing the airflow excitation force.

[0026] According to an embodiment of the present invention, the steam guide rod is connected to the turbine cylinder through a fixing member. The closed end of the steam guide rod is close to the root of the stationary blade and the moving blade. The diameter of the jet hole is set according to the size of the last stage blade and the steam flow requirement. The steam parameters provided by the external steam source are matched with the steam parameters of the last stage of the turbine to avoid secondary vibration caused by sudden changes in steam parameters.

[0027] According to an embodiment of the present invention, in step 3, the damping enhancement structure suppression specifically involves: generating a dry friction effect through the dry friction damping blocks on both sides of the blade crown, consuming the blade vibration energy, increasing the blade damping, and reducing the blade vibration response and dynamic stress; the dry friction damping block is a triangular structure, set at a distance of 0.2-0.25L from the top of the blade crown, where L is the length of the intermediate connecting body of the blade, and the thickness of the damping block is h=(1 / 2)Hsinθ, where H is the thickness of the blade root and θ is the torsion angle of the intermediate connecting body.

[0028] According to an embodiment of the present invention, the intermediate connecting body between the dry friction damping block and the blade, the blade root and the blade crown are machined in one piece from high-strength corrosion-resistant steel. Both the damping block and the blade root are provided with round chamfers with the same chamfer radius to avoid stress concentration.

[0029] According to an embodiment of the present invention, in step 4, the preset safety threshold is vibration amplitude ≤ 0.5 mm and aerodynamic damping Δ ≥ 0. If the vibration parameters still do not meet the standard after 3 adjustments, an alarm signal is issued and the turbine load reduction or shutdown protection mechanism is triggered.

[0030] To achieve the above-mentioned objectives, the second technical solution adopted by the present invention is: a flue gas treatment system for achieving emission standards under low load conditions, comprising a processor, a memory, and at least one program, wherein the program is stored in the memory and configured to be executed by the processor, and the program includes instructions for executing a method for treating the vibration of the last stage blades of a steam turbine under low load conditions.

[0031] In summary, the present invention has the following advantages compared with the prior art: 1. This invention can quickly identify vibration risks and avoid intervention delays by precisely setting the judgment criteria for low-load vibration risk conditions (load is less than 50% of rated load, the back pressure of the last stage steam increases by 15 kPa or more, and the steam flow rate is in the low flow range). At the same time, it adopts a dual-path vibration suppression strategy of steam compensation and damping enhancement. It not only adjusts the steam flow field in the last stage flow area from the source to eliminate airflow excitation causes such as eddies, blasting and steam backflow, but also consumes the blade vibration energy through the damping enhancement structure. The dual action achieves efficient vibration suppression. Compared with a single suppression scheme, the vibration suppression stability is improved by more than 30%, which can effectively control the blade vibration amplitude within the safe threshold.

[0032] 2. The steam compensation unit adopts a structure in which a hollow steam guide rod is used in conjunction with an external steam source. This eliminates the need for significant modifications to the main structure of the turbine's last-stage blades. The steam guide rod is connected to the cylinder via a fixing component, making installation convenient. The damping enhancement unit uses a dry friction damping block machined integrally with the blades. This eliminates the need for additional complex damping mechanisms, resulting in lower processing difficulty and controllable costs. Compared to existing structural modification schemes, this reduces modification costs by more than 40%, and requires no additional energy consumption during operation. It is suitable for upgrading and modifying various existing steam turbines.

[0033] 3. This invention uses a monitoring module to collect operating parameters and vibration parameters in real time, a judgment module to accurately determine the operating condition, and a feedback adjustment module to adjust the suppression strategy in real time based on the vibration parameters, forming a closed-loop control system of "monitoring-judgment-suppression-feedback-adjustment". This system can track vibration changes in real time and avoid vibration rebound. At the same time, an alarm module and a protection module are added. When the vibration parameters fail to meet the standard after multiple adjustments, an alarm is issued in time and a shutdown protection is triggered. This effectively avoids serious failures such as fatigue cracks and fractures of the blades due to excessive vibration, significantly improves the safety and reliability of turbine operation, and reduces downtime losses.

[0034] 4. The steam compensation parameters and damping block dimensions of this invention can be flexibly adjusted according to the dimensions and operating parameters of the last-stage blades of different turbine models. The jet orifice diameter, damping block installation position and thickness can be adapted accordingly. There is no need to design a separate scheme for different turbine models. It is suitable for vibration treatment of the last-stage blades of various subcritical and supercritical turbines and has a wide range of applications.

[0035] 5. The monitoring module uses a high-precision laser vibration meter, pressure sensor, and flow sensor, in conjunction with an NI DAQmx acquisition card. The vibration parameter sampling rate is no less than 10kHz and the accuracy is no less than 0.01mm. The operating parameter acquisition response is rapid. At the same time, the vibration data is filtered and preprocessed to effectively remove interference signals and ensure the accuracy of the acquired data, providing reliable data support for operating condition judgment and vibration suppression strategy adjustment.

[0036] Those skilled in the art will understand that, for ease of explanation, the example is provided with one memory and one processor. In actual terminals or servers, multiple processors and memories may exist. Memory can also be referred to as storage medium or storage device, etc., and the embodiments of this application do not limit this.

[0037] It should be understood that in the embodiments of this application, the processor may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The processor may also be a general-purpose microprocessor, graphics processing unit (GPU), or one or more integrated circuits to execute relevant programs to achieve the functions required by the embodiments of this application.

[0038] The processor can also be an integrated circuit chip with signal processing capabilities. In implementation, each step of this application can be completed through integrated logic circuits in the processor hardware or instructions in software form. The aforementioned processor can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The steps of the method for treating the vibration of the last stage blade of a steam turbine under low load conditions disclosed in the embodiments of this application can be directly manifested as execution by a hardware decoding processor, or execution by a combination of hardware and software modules in the decoding processor. The software modules can be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory; the processor reads the information in the memory and, in conjunction with its hardware, completes the functions required by the units included in the method, system, and storage medium for treating the vibration of the last stage blade of a steam turbine under low load conditions in the embodiments of this application.

[0039] It should also be understood that the memory mentioned in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. Non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory can be random access memory (RAM), which is used as an external cache.

[0040] By way of example, but not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDR SDRAM), Enhanced Synchronous DRAM (ESDRAM), Synchlink DRAM (SLDRAM), and Direct Rambus RAM (DR RAM).

[0041] The memory can also be a Compact Disc Read-Only Memory (CD-ROM) or other optical disc storage, optical disk storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media, or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures that can be accessed by a computer, but is not limited thereto. The memory can exist independently and be connected to the processor via a bus. The memory can also be integrated with the processor. The memory can store programs, and when the program stored in the memory is executed by the processor, the processor performs the various steps of the method determined in the above embodiments of this application.

[0042] It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA, or other programmable logic device, discrete gate or transistor logic device, or discrete hardware component, the memory (storage module) is integrated into the processor. It should be noted that the memory described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0043] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0044] In implementation, each step of the above method can be completed by the integrated logic circuits in the processor's hardware or by instructions in software. The steps of the method for handling the vibration of the last-stage turbine blades under low-load conditions disclosed in the embodiments of this application can be directly implemented by the hardware processor, or by a combination of hardware and software modules in the processor. The software modules can be located in mature storage media in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. Since this storage medium is located in memory, the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, these will not be described in detail here.

[0045] Those skilled in the art will recognize that the various illustrative logical blocks (ILBs) and steps described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. 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 application.

[0046] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer-programmed program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a processor, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a computer network, or other programmable device.

[0047] This embodiment also provides a computer-readable storage medium storing a computer program that enables a computer to execute in order to implement the above-described method for handling the vibration of the last stage blade of a steam turbine under low-load conditions based on multi-stage vortex and intelligent feedforward.

[0048] It should be noted that computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic) or wireless (e.g., infrared, wireless, microwave, etc.) means, or from one website, computer, server, or data center to a mobile phone processor via a wired means. A computer-readable storage medium can be any usable medium that a computer can access, or a data storage system such as a server or data center that integrates one or more usable media. Usable media can be magnetic media (e.g., floppy disks, hard disks), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state drives), etc.

[0049] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for treating vibration of the last-stage blades of a steam turbine under low-load conditions, characterized in that, Includes the following steps: Step 1: Monitor the turbine operating parameters and the vibration parameters of the last stage blades in real time. The operating parameters include turbine load, last stage steam back pressure, and steam flow rate. The vibration parameters include blade vibration frequency, vibration amplitude, and aerodynamic damping Δ. Step 2: Determine whether the steam turbine is under low load conditions. When the steam turbine load is less than 50% of the rated load, and the back pressure of the last stage steam rises to more than 15 kPa and the steam flow rate is in the low flow range, it is determined to be a low load vibration risk condition. Step 3: When the low-load vibration risk condition is determined, the dual-path vibration suppression strategy is activated. The steam flow field in the final stage flow region is adjusted by steam compensation, and the blade vibration response is suppressed by the damping enhancement structure. Step 4: Continuously monitor vibration parameters. When the blade vibration amplitude drops below the preset safety threshold and the aerodynamic damping Δ≥0, stop the dual-path vibration suppression strategy and restore normal operation. If the vibration parameters do not meet the standards, adjust the steam compensation parameters and the damping structure strength until the safety operation requirements are met.

2. The method for treating vibration of the last-stage turbine blades under low-load conditions according to claim 1, characterized in that, In step 1, the vibration parameters are acquired in real time by a laser vibrometer with a sampling rate of not less than 10kHz. The operating parameters are acquired synchronously by a pressure sensor and a flow sensor with a data acquisition duration of not less than 60s / set. After acquisition, the vibration data is filtered and preprocessed with a filter cutoff frequency of 200Hz.

3. The method for treating vibration of the last-stage turbine blades under low-load conditions according to claim 1, characterized in that, In step 3, the steam compensation adjustment specifically involves introducing external steam into the root of the last stage stationary and moving blades through multiple hollow steam guide rods. Multiple jet holes are opened on the side of the steam guide rods near the closed end. The external steam forms a positive airflow by utilizing the pressure difference inside and outside the turbine, thereby changing the steam flow rate, velocity distribution, and pressure in the last stage flow area, reducing eddy current generation, suppressing the blow-by phenomenon, preventing steam backflow, and reducing the airflow excitation force.

4. The method for treating vibration of the last-stage turbine blades under low-load conditions according to claim 3, characterized in that, The steam guide rod is connected to the turbine cylinder through a fixing component. The closed end of the steam guide rod is close to the root of the stationary blade and the moving blade. The diameter of the jet hole is set according to the size of the last stage blade and the steam flow requirement. The steam parameters provided by the external steam source are matched with the steam parameters of the last stage of the turbine to avoid secondary vibration caused by sudden changes in steam parameters.

5. The method for treating vibration of the last-stage turbine blades under low-load conditions according to claim 1, characterized in that, In step 3, the damping enhancement structure specifically suppresses the vibration by generating a dry friction effect through the dry friction damping blocks on both sides of the blade crown, consuming the blade vibration energy, increasing the blade damping, and reducing the blade vibration response and dynamic stress. The dry friction damping block is a triangular structure, set at a distance of 0.2-0.25L from the top of the blade crown, where L is the length of the intermediate connecting body of the blade, and the thickness of the damping block is h=(1 / 2)Hsinθ, where H is the thickness of the blade root and θ is the torsion angle of the intermediate connecting body.

6. The method for treating vibration of the last-stage turbine blades under low-load conditions according to claim 5, characterized in that, The intermediate connecting body between the dry friction damping block and the blade, the blade root and the blade crown are machined in one piece from high-strength corrosion-resistant steel. Both the damping block and the blade root are provided with round chamfers with the same chamfer radius to avoid stress concentration.

7. The method for treating vibration of the last-stage turbine blades under low-load conditions according to claim 1, characterized in that, In step 4, the preset safety threshold is a vibration amplitude ≤ 0.5 mm and a pneumatic damping Δ ≥ 0. If the vibration parameters still do not meet the standard after 3 adjustments, an alarm signal will be issued, and the turbine load reduction or shutdown protection mechanism will be triggered.

8. A flue gas treatment and emission standard compliance system under low load conditions, characterized in that, The device includes a processor, a memory, and at least one program, the program being stored in the memory and configured to be executed by the processor, the program including instructions for performing a method for treating the vibration of the last stage blade of a steam turbine under low load conditions as described in any one of claims 1-7.

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