A composite sensor and a measuring method for real-time measurement of operating state of a steam turbine blade

Abstract

This invention belongs to the field of steam turbine testing technology, specifically relating to a composite sensor and measurement method for real-time measurement of the operating status of steam turbine blades. It includes a housing, which is a cylindrical structure closed at one end and open at the other. A temperature measurement module and a soft magnetic core are installed inside the closed section of the housing. An inductive inductor is fitted around the soft magnetic core. A permanent magnet and a high-temperature silicone sealing area are sequentially arranged on the side end of the inductive inductor. An end cap is connected to the open section of the housing, and a channel is formed on the side wall of the end cap. The temperature measurement module is connected to a lead wire via a high-frequency cable. The soft magnetic core is also connected to the high-frequency cable, which passes sequentially through the permanent magnet and the high-temperature silicone sealing area and connects to the lead wire. The beneficial effects are: this invention can achieve spatiotemporal synchronization of monitoring data, measuring three parameters at the same location and time, eliminating correlation errors caused by separate sensors due to different installation positions or asynchronous sampling times.

Description

Technical Field

[0001] This invention belongs to the field of steam turbine testing technology, specifically relating to a composite sensor and measurement method for real-time measurement of the operating status of steam turbine blades. Background Technology

[0002] Turbine blades (especially those in the high-temperature, high-pressure section) are core rotating components, and their health directly affects the safety and efficiency of the unit. A single parameter cannot fully reflect the complex operating conditions of the blades; multiple parameters are needed to reflect their actual condition, including temperature, vibration, and clearance. Simultaneously, the monitoring data needs to be integrated into a single design. These three parameters must be measured simultaneously and at the same location to be meaningful. When a rotating blade passes the sensor, temperature reflects the cooling effect, clearance indicates blade expansion, and vibration reflects dynamic directional changes. Only by combining these three data points can a true reflection of the blade's condition be obtained.

[0003] Turbine blades are rotating components in nuclear power plants, and their health directly affects the safety and efficiency of the unit. A single parameter cannot fully reflect the complex operating conditions of the blades. It is necessary to simultaneously feed back multiple parameters such as temperature, vibration, and clearance. Temperature is needed to reflect the thermal stress level of the blades, vibration monitoring is needed to reflect the dynamic stress and mechanical damage (such as cracks and loosening) of the blades, and tip clearance monitoring is needed to reflect the clearance value between moving and stationary components, and to feed back dynamic changes such as thermal expansion and centrifugal force. This is to prevent excessive clearance from increasing leakage losses and insufficient clearance from causing friction and abrasion. No single parameter can fully reflect the blade condition. In addition, a single sensor cannot meet the time synchronization requirements. Therefore, a sensor device that couples these three types of characteristics is required. Summary of the Invention

[0004] The purpose of this invention is to provide a composite sensor and method for real-time measurement of the operating status of steam turbine blades, which has a compact structure, is less affected by environmental factors, and has a relatively low cost.

[0005] The technical solution of the present invention is as follows: A composite sensor for real-time measurement of the operating status of turbine blades includes a housing, a temperature measurement module, an end cap, an armored lead wire, a high-temperature silicone sealing area, a permanent magnet, a soft magnetic core, and an inductive inductor. The housing is a cylindrical structure with one end closed and the other end open. The temperature measurement module and the soft magnetic core are installed inside the closed section of the housing. An inductive inductor is fitted around the soft magnetic core. The side end of the inductive inductor is sequentially provided with a permanent magnet and a high-temperature silicone sealing area. The open section of the housing is connected to an end cap, and the side wall of the end cap has a channel. The temperature measurement module is connected to a lead wire via a high-frequency cable. The soft magnetic core is connected to a high-frequency cable. The high-frequency cable passes sequentially through the permanent magnet and the high-temperature silicone sealing area and is connected to the lead wire.

[0006] The shell has an external thread structure on its side wall.

[0007] The oscillating inductor generates an oscillating electromagnetic field. The object being measured passes through the magnetic field and reflects the energy of the oscillating electromagnetic field, causing a change in the magnetic field around the metal conductor, forming an induced current, which is a closed loop.

[0008] The induction coil of the inductive inductor is made of a high-temperature resistant enameled wire wound magnetic core.

[0009] The housing is made of stainless steel TC4 titanium alloy.

[0010] The lead-out line is fitted with an armored sheath.

[0011] Measurement methods using sensors include the following:

[0012] Blade vibration measurement determines the vibration displacement value by measuring the time of its change. The radial vibration displacement of the blade during that pass is calculated by measuring the deviation Δt between the actual arrival time and the theoretically equal-interval arrival time of the signal peak for each blade. The calculation formula is as follows:

[0013]

[0014] Δt=t 实际达到时间 -t 理论达到时间

[0015] Where: A is the vibration amplitude; V tip Blade tip linear velocity; blade tip radius R;

[0016] Formula for calculating blade tip linear velocity

[0017] Vibration displacement calculation formula: d≈Δt·V tip

[0018] Theoretical arrival time interval calculation formula

[0019] Gap measurement, V established through static calibration peak Quantitative relationship with gap d:

[0020]

[0021] Where: k is the sensitivity coefficient, n is the nonlinear exponent, and C is the offset;

[0022] Actual measurement of the through signal V for each blade peak Substitute the values ​​into the calibration formula to solve for the gap:

[0023]

[0024] Temperature measurement is achieved by adding a platinum resistance thermometer module to the sensor. The resistance value Rt of the platinum resistance thermometer has a definite functional relationship with the temperature t.

[0025] R T =R0(1+At+Bt) 2 )

[0026] Where: R t Rt is the resistance value at temperature t℃, R0 is the nominal resistance value at 0℃, and A, B, and C are the characteristic constants of platinum material.

[0027] The beneficial effects of this invention are as follows: It enables spatiotemporal synchronization of monitoring data, measuring three parameters at the same location and time, eliminating correlation errors caused by different installation positions or asynchronous sampling times of separate sensors. Simultaneously, it accurately captures the instantaneous coupling relationship between parameters, such as whether the vibration peak is related to temperature changes or sudden gap changes. It achieves correlation analysis through data fusion. Raw data can be analyzed in real time at the sensor end. It significantly improves fault diagnosis accuracy and reduces the possibility of false alarms / missed alarms. It reduces installation complexity. Single-point installation replaces multiple independent sensors, reducing the number of openings. It simplifies wiring, reduces the risk of seal failure and signal interference, and improves system reliability. It improves the signal-to-noise ratio and accuracy. The integrated design optimizes sensor component layout, reduces environmental interference, uses a common signal conditioning circuit, and ensures more consistent calibration, avoiding the cumulative errors of independent calibration of multiple sensors. Attached Figure Description

[0028] Figure 1 A schematic diagram of a composite sensor for real-time measurement of the operating status of steam turbine blades provided by the present invention;

[0029] Figure 2 This is a graph showing the relationship between voltage and time during blade vibration.

[0030] In the diagram: 1. Housing, 2. Temperature measurement module, 3. Housing sidewall, 4. End cap, 5. Lead wire, 6. High-temperature silicone sealing area, 7. Permanent magnet, 8. Soft magnetic core, 9. Inductive inductor. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] This invention provides a composite sensor for real-time measurement of the operating status of turbine blades, integrating temperature, vibration, and clearance monitoring of the last-stage blades in nuclear power turbines. Due to limitations in installation space, environmental influences, and cost, this sensor, designed as an integrated monitoring device for temperature, vibration, and clearance of the last-stage blades in nuclear power turbines, features a compact structure, minimal susceptibility to environmental factors, and relatively low cost, overcoming the shortcomings of ordinary sensors and being particularly suitable for online condition monitoring of turbine blades. It also offers numerous engineering advantages, reducing the number of openings to maintain cylinder / diaphragm strength, simplifying wiring with a unified signal interface, and requiring calibration and maintenance only for a single device. More importantly, since each additional sensor on turbine equipment increases the risk of seal failure, the integrated design significantly improves system safety and reliability. Furthermore, to prevent the risk of falling, a boss structure is designed to prevent it from dropping.

[0033] like Figure 1 As shown, a composite sensor for real-time measurement of the operating status of steam turbine blades includes a housing 1, a temperature measurement module 2, a housing sidewall 3, an end cap 4, an armored lead wire 5, a high-temperature silicone sealing area 6, a permanent magnet 7, a soft magnetic core 8, and an inductor 9. The housing 1 is a cylindrical structure with one end closed and the other open. The temperature measurement module 2 and the soft magnetic core 8 are installed inside the closed section of the housing 1. The inductor 9 is fitted around the soft magnetic core 8. The permanent magnet 7 and the high-temperature silicone sealing area 6 are sequentially arranged on the side end of the inductor 9. The open section of the housing 1 is connected to an end cap, and the sidewall of the end cap has a channel. The temperature measurement module 2 is connected to the lead wire 5 via a high-frequency cable. The soft magnetic core 8 is connected to the high-frequency cable. The high-frequency cable passes through the permanent magnet 7 and the high-temperature silicone sealing area 6 sequentially and connects to the lead wire 5. The lead wire 5 is covered with an armored sheath. The housing sidewall 3 of the housing 1 has an external thread structure.

[0034] The inductor 9 oscillates to generate an oscillating electromagnetic field. The object being measured passes through the magnetic field and reflects the energy of the oscillating electromagnetic field, causing a change in the magnetic field around the metal conductor, forming an induced current in a closed loop, which is transmitted through the wiring harness. The induction coil of the inductor 9 is made of high-temperature resistant enameled wire wound with a magnetic core, providing good current blocking, tuning, and frequency selection. The permanent magnet 7 is used to generate a fixed magnetic field. The temperature measurement module 2 uses an advanced temperature sensing chip, which has advantages such as small size, excellent long-term stability, and high accuracy over a wide temperature range. The housing 1 is made of stainless steel TC4 titanium alloy, which has advantages such as corrosion resistance, heat resistance, and good mechanical properties. The high-frequency cable is used to transmit high-frequency signals and is anti-interference and high-temperature resistant. The lead wire 5 is equipped with an armored sheath to protect the cable and enhance the strength of the device. The high-frequency connector has advantages such as convenient connection and resistance to damage. The high-temperature silicone used ensures that the measuring element is isolated from the outside.

[0035] The principle of this invention for measuring blade condition comprises three aspects: measuring blade vibration based on the tip-time measurement principle, measuring blade tip clearance based on the static calibration method, and measuring the ambient temperature around the blade based on the resistance-temperature characteristics. By integrating these three different measurement methods, simultaneous online monitoring of blade vibration, clearance, and temperature is achieved.

[0036] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0037] The measurement process using this invention is as follows:

[0038] (1) Blade vibration measurement: Based on the principle of tip-time measurement, blades are typically made of ferromagnetic materials. When the blade is stationary or rotating uniformly without vibration, the distance (gap) the blade tip travels past the fixed position of the sensor each time is constant. When the blade vibrates, the time it takes for the blade tip to reach the sensor changes. By measuring this change in time, the vibration displacement value can be determined. Therefore, by measuring the deviation (Δt) between the actual arrival time of each blade signal peak and the theoretically equal-interval arrival time, the radial vibration displacement of the blade during that passage can be calculated. The calculation formula is as follows:

[0039]

[0040] Δt=t 实际达到时间 -t 理论达到时间

[0041] Where: A: vibration amplitude; V tip : Tip linear velocity; R: Tip radius.

[0042] Formula for calculating blade tip linear velocity

[0043] Vibration displacement calculation formula d≈Δ t ·V tip

[0044] Theoretical arrival time interval calculation formula

[0045] (2) Gap Measurement Principle: The blade gap is measured by calibration. Since the actual blade gap cannot be measured solely by magnetoresistive methods, static calibration can be used for measurement in this case. When the measuring blade rotates past the sensor, a pulse voltage signal is output, such as... Figure 2 The pulse peak voltage V is described above. peak The position of the blade closest to the sensor, i.e., the minimum gap point.

[0046] V is established through static calibration. peak Quantitative relationship with gap d:

[0047] (Nonlinear equations)

[0048] Where: k: sensitivity coefficient, n: nonlinearity exponent (usually 1.5 to 3); C: offset.

[0049] Actual measurement of the through signal V for each blade peak Substitute the values ​​into the calibration formula to solve for the gap:

[0050]

[0051] (3) Temperature measurement method. By adding a platinum resistance thermometer module to the sensor, there is a definite functional relationship between the resistance value Rt of the platinum resistance thermometer and the temperature t.

[0052] R T =R0(1+At+Bt) 2 (0℃≤t≤850℃)

[0053] Where: R t R0: Nominal resistance value (Ω) at temperature t℃. R0: Nominal resistance value at 0℃ (commonly 100Ω or 1000Ω). A, B, C: Characteristic constants of platinum material (specified by international standards). By combining the platinum resistance thermometer module and the magnetoresistive module in a single sensor, simultaneous measurement of temperature, vibration, and gap can be achieved.

Claims

1. A composite sensor for real-time measurement of the operating status of steam turbine blades, characterized in that: The device includes a housing, a temperature measurement module, an end cap, armored cables, a high-temperature silicone sealing area, a permanent magnet, a soft magnetic core, and an inductor. The housing is a cylindrical structure that is closed at one end and open at the other. The temperature measurement module and the soft magnetic core are installed inside the closed section of the housing. An inductor is fitted around the soft magnetic core. The permanent magnet and the high-temperature silicone sealing area are sequentially arranged on the side end of the inductor. An end cap is connected to the open section of the housing. The side wall of the end cap has a channel. The temperature measurement module is connected to the lead wire via a high-frequency cable. The soft magnetic core is connected to the high-frequency cable. The high-frequency cable passes through the permanent magnet and the high-temperature silicone sealing area and is connected to the lead wire.

2. The composite sensor for real-time measurement of turbine blade operating status as described in claim 1, characterized in that: The shell has an external thread structure on its side wall.

3. The composite sensor for real-time measurement of turbine blade operating status as described in claim 1, characterized in that: The oscillating inductor generates an oscillating electromagnetic field. The object being measured passes through the magnetic field and reflects the energy of the oscillating electromagnetic field, causing a change in the magnetic field around the metal conductor, forming an induced current, which is a closed loop.

4. The composite sensor for real-time measurement of turbine blade operating status as described in claim 1, characterized in that: The induction coil of the inductive inductor is made of a high-temperature resistant enameled wire wound magnetic core.

5. The composite sensor for real-time measurement of turbine blade operating status as described in claim 1, characterized in that: The housing is made of stainless steel TC4 titanium alloy.

6. The composite sensor for real-time measurement of turbine blade operating status as described in claim 1, characterized in that: The lead-out line is fitted with an armored sheath.

7. The measurement method using the sensor described in claims 1-6, characterized in that: Blade vibration measurement determines the vibration displacement value by measuring the time of its change. The radial vibration displacement of the blade during that pass is calculated by measuring the deviation Δt between the actual arrival time and the theoretically equal-interval arrival time of the signal peak for each blade. The calculation formula is as follows: Δt=t 实际达到时间 -t 理论达到时间 Where: A is the vibration amplitude; V tip Blade tip linear velocity; blade tip radius R; Formula for calculating blade tip linear velocity Vibration displacement calculation formula d≈Δ t ·V tip Theoretical arrival time interval calculation formula Gap measurement, V established through static calibration peak Quantitative relationship with gap d: Where: k is the sensitivity coefficient, n is the nonlinear exponent, and C is the offset; Actual measurement of the through signal V for each blade peak Substitute the values ​​into the calibration formula to solve for the gap: Temperature measurement is achieved by adding a platinum resistance thermometer module to the sensor. The resistance value Rt of the platinum resistance thermometer has a definite functional relationship with the temperature t. R T =R0(1+At+Bt 2 ) Where: R t R is the resistance value at temperature t℃, R0 is the nominal resistance value at 0℃, and A, B, and C are the characteristic constants of platinum material.

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