Monitoring device and method for uneven settlement of steam turbine foundation

Abstract

The present invention discloses a monitoring device for uneven settlement of a steam turbine foundation, comprising a control unit, a mounting base plate, a cylinder, a support plate disposed within the cylinder, an inclined plate, a counterweight, and a strain sensor. The top of the inclined plate is connected to the support plate, and the bottom of the inclined plate is connected to the counterweight. The strain sensor is disposed at one end of the inclined plate near the support plate. The strain sensor is used to collect bending strain data of the inclined plate, and the control unit is used to collect data and perform calculations. The monitoring device for uneven settlement of a steam turbine foundation of the present invention is based on strain measurement technology and has an accuracy of up to 1*10 ‑6 The device has high stability and can be used to monitor the tilt of steam turbine platforms during their long service life.

Description

Technical Field

[0001] The present invention belongs to the field of steam turbine foundation settlement monitoring, and specifically relates to a monitoring device for uneven settlement of a steam turbine foundation and a monitoring method based on the monitoring device, which is used to monitor the uneven settlement of each support point under long-term operation conditions of the steam turbine platform to avoid overall deformation of the steam turbine foundation. Background Art

[0002] The turbine foundation utilizes a monolithic concrete frame structure, bearing the weight of the turbine, generator, and condenser, resulting in a significant total weight. Since the foundation was poured, the turbine foundation has experienced structural settlement. Due to the uneven distribution of equipment weight, the turbine frame foundation is structurally misaligned longitudinally, with the generator side being heavier and the turbine side being lighter. In terms of settlement variability, the generator side experiences the greatest foundation settlement. If operating loads such as the condenser water injection test are considered, foundation settlement becomes even more pronounced, resulting in a slight tilt of the entire platform. Furthermore, due to the uneven distribution of surrounding equipment and buildings, settlement at each support point varies significantly. This can lead to variations in bearing elevation and journal lift, equipment flatness, shaft misalignment, and increased piping stress, impacting the normal operation of the turbine and even causing plastic deformation of connected pipelines. Therefore, monitoring of turbine platform settlement is necessary.

[0003] At present, in the field of steam turbine uneven settlement monitoring, the following three forms are basically adopted:

[0004] 1) Use a laser tracking device to measure the spatial position information of each observation point on the turbine platform.

[0005] For example, the patent application with application number 202011227622.X and titled “Steam Turbine Platform Settlement Monitoring Method, Device and Computer Equipment” measures the key point spatial positions and reference target sphere spatial positions of each object to be measured at different observation positions in the target space by a laser tracking device; the reference target sphere spatial position is the spatial position of the reference target sphere in the target space; based on the key point spatial positions and reference target sphere spatial positions measured at each of the observation positions, the key points of each object to be measured are fitted into the same pre-established spatial coordinate system; based on the vertical spatial coordinate values of each key point in the spatial coordinate system, the elevation information corresponding to each object to be measured is determined; the elevation information is used to monitor the settlement of the steam turbine generator foundation platform. This method requires the establishment of spatial position information of the steam turbine, has high requirements on equipment performance, and is relatively costly.

[0006] 2) Manual observation method based on level and level rod.

[0007] Select a settlement point as the leveling working point and perform Class II leveling using a closed route. The foundation settlement can be obtained through multiple round trip measurements. This method requires high equipment accuracy and operator skills, and is significantly affected by the external environment and temperature. It cannot be carried out in conditions of strong winds, sudden temperature changes, or strong sunlight.

[0008] 3) Monitoring method based on improved level instrument.

[0009] This method uses an anti-interference static level instrument, arranges multiple observation points, and transmits settlement data to a data acquisition device via an RS485 serial port to monitor the turbine foundation. The levels are connected in series with liquid pipes, and relative settlement is measured by pressure fluctuations caused by changes in liquid level. However, this method is not suitable for use in cold regions. Summary of the Invention

[0010] In view of this, in order to overcome the defects of the prior art, the purpose of the present invention is to provide a monitoring device for uneven settlement of a steam turbine foundation and a monitoring method based on the monitoring device, wherein the monitoring device has high stability and simple measurement.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions:

[0012] A monitoring device for uneven settlement of a steam turbine foundation includes a control unit and a mounting base plate, a cylinder, a support plate arranged in the cylinder, an inclined plate, a counterweight, and a strain sensor. The top of the inclined plate is connected to the support plate, and the bottom of the inclined plate is connected to the counterweight. The strain sensor is arranged at one end of the inclined plate close to the support plate. The strain sensor is used to collect bending strain data of the inclined plate. The control unit is used to collect data and perform calculations.

[0013] According to some preferred implementation aspects of the present invention, the inclined plate includes a first inclined plate and a second inclined plate, and vertical planes where the first inclined plate and the second inclined plate are located when not inclined are perpendicular to each other.

[0014] According to some preferred embodiments of the present invention, the counterweight block includes a first counterweight block and a second counterweight block respectively arranged at the lower ends of the first inclined plate and the second inclined plate; the strain sensor includes a first strain sensor and a second strain sensor respectively arranged at the upper ends of the first inclined plate and the second inclined plate.

[0015] According to some preferred implementation aspects of the present invention, the strain sensor comprises a uniaxial strain gauge, and the uniaxial strain gauge is arranged along a length extension direction of the inclined plate.

[0016] According to some preferred implementation aspects of the present invention, the monitoring device is installed at one or more locations upstream of the high-pressure cylinder or the medium-pressure cylinder, on both sides of the low-pressure cylinder, or on both sides of the generator or the exciter.

[0017] According to some preferred embodiments of the present invention, the cylinder includes an upper cylinder portion and a lower cylinder portion, a gasket is arranged between the upper cylinder portion and the lower cylinder portion; the bottom of the lower cylinder portion is fixed on the mounting base plate; the support plate, inclined plate, counterweight block, and strain sensor are arranged in the lower cylinder portion.

[0018] According to some preferred embodiments of the present invention, a hole penetrating the wall thickness is provided on the cylinder for vacuuming the cylinder.

[0019] A method for monitoring uneven settlement of a steam turbine foundation based on the above-mentioned monitoring device of the present invention comprises the following steps:

[0020] 1) Preprocess the collected bending strain data of the inclined plate to eliminate abnormal data caused by external accidental collision.

[0021] Strain gauges are used as data acquisition sensors, which are very sensitive to external interference. However, the settlement and tilt of the turbine platform are long-term gradual processes, with very small changes per unit time. Therefore, a low-frequency filtering method is used to pre-process the data. The filter frequency is set to 0.001Hz to eliminate abnormal signals caused by external interference.

[0022] 2) According to Hooke's law, calculate the bending stress on the inclined plate.

[0023] The formula is as follows:

[0024] σ=E*ε Formula (1)

[0025] In formula (1), σ is the bending stress, E is the elastic modulus, and ε is the bending strain, which are obtained from step 1).

[0026] 3) Based on the Euler beam formula, the tilt angle of the tilted plate corresponding to the bending stress generated is reversely calculated using the formula for the tilted plate's bending moment and the bending stress at the root of the cantilever beam. This reverse calculation formula can then be used to determine the tilt of the turbine platform.

[0027] M 弯曲 =σ*W Z Formula (2)

[0028] In formula (2), M 弯曲 is the bending moment of the inclined plate at the center line of the strain gauge, σ is the bending stress, W z is the bending section modulus of the inclined plate;

[0029] At the same time, M 弯曲And it satisfies the following formula:

[0030] M 弯曲 =FL=m*g*cosθ*L Formula (3)

[0031] In formula (3), L is the length from the center of gravity of the counterweight to the center line of the strain gauge, θ is the inclination angle of the tilt plate, m is the mass of the counterweight, and g is the acceleration of gravity, which is 9.8 N / Kg.

[0032] According to formula (2) and formula (3), we can get formula (4):

[0033]

[0034] Then, according to formula (4), we can get formula (5):

[0035]

[0036] The tilt angle of the tilt plate is obtained by formula (5).

[0037] The inclination angles of the two inclined plates are calculated by the above formula, and then the inclination amount of the turbine platform is obtained, which is the inclination angles of the two inclined plates.

[0038] Due to the adoption of the above technical solutions, compared with the prior art, the present invention is beneficial in that: the monitoring device for uneven settlement of the steam turbine foundation of the present invention is based on strain measurement technology, and its accuracy can reach 1*10 -6 The device has high stability and can be used to monitor the tilt of steam turbine platforms during their long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 Schematic diagram of the structure of the monitoring device for uneven settlement of a steam turbine foundation in preferred embodiment 1 of the present invention;

[0041] Figure 2 Schematic diagram showing the comparison of the bending strain data signal before and after filtering in the preferred embodiment 2 of the present invention; wherein, Figure 2 The upper part is the bending strain data signal before processing. Figure 2 The lower part is the processed bending strain data signal;

[0042] In the accompanying drawings, control unit-1, mounting base-2, upper cylinder-3, lower cylinder-4, support plate-5, tilting plate-6, counterweight block-7, strain gauge-8, gasket-9, hole-10, connecting ear-11. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0044] The monitoring device and monitoring method of the present invention are based on structural strain testing technology. The strain data of the inclined plate is collected and the inclination rate is reversely calculated using Hooke's law to obtain the inclination amount of the turbine platform.

[0045] Example 1 Monitoring device

[0046] like Figure 1 As shown, the device for monitoring uneven settlement of a steam turbine foundation in this embodiment includes a control unit, a mounting base, a cylinder, a support plate disposed within the cylinder, an inclined plate, a counterweight, and a strain sensor. The top of the inclined plate is connected to the support plate, and the bottom of the inclined plate is connected to the counterweight. The strain sensor is disposed at one end of the inclined plate near the support plate and is used to collect bending strain data of the inclined plate. The strain sensor is electrically connected to the control unit, which is responsible for collecting data and performing calculations. The inclined plate in this embodiment is a stainless steel foil strip, preferably 1000 mm in height, 50 mm in width, and 10 mm in thickness. It is suspended from the support plate within the protective cylinder by welding, and a counterweight is mounted at the bottom.

[0047] To ensure reasonable and accurate results, the inclined plates in this embodiment include a first inclined plate and a second inclined plate. In their initial state (when not bent), the two inclined plates are perpendicular to each other. Specifically, the mounting surfaces of the first and second inclined plates form a 90° angle, collecting horizontal deformation in two mutually perpendicular directions. Furthermore, the dimensions of the cylinder ensure that the two counterweights do not interfere with each other.

[0048] Correspondingly, the counterweights include first and second counterweights, respectively positioned at the lower ends of the first and second inclined plates; and the strain sensors include first and second strain sensors, respectively positioned at the upper ends of the first and second inclined plates. The strain sensors include uniaxial strain gauges, positioned along the length of the inclined plates to ensure accurate measurement results.

[0049] The cylinder consists of an upper and lower portion, secured with connecting lugs and sealed with a fluorine-based gasket. The bottom of the lower portion is fixed to the mounting base. The support plate, tilting plate, counterweight, and strain sensor are housed within the lower portion. A through-wall hole is provided in the cylinder to evacuate the interior, maintaining a vacuum state. This ensures that the internal environment does not affect the stability of the strain gauge wire foil, eliminates factors that hinder the movement of the tilting plate, and allows data cables to be routed through the hole.

[0050] The monitoring device is installed on the turbine foundation platform while the entire unit is in a vacuum state. Depending on the turbine type and power, the monitoring device is installed upstream of the high-pressure or intermediate-pressure cylinder, on both sides of the low-pressure cylinder, or on both sides of the generator or exciter, or in one or more locations.

[0051] When a turbine platform experiences uneven settlement, the tilting plate deforms as the bottom counterweight moves, generating strain changes at the base. This strain data is monitored over a long period of time using an acquisition module, which only considers the bending strain of the tilting plate and ignores strains caused by temperature, deadweight, and other factors.

[0052] Example 2 Monitoring method

[0053] The method for calculating uneven settlement of a steam turbine foundation in this embodiment is based on the monitoring device described in Example 1. The inclined plate has a length B = 50 mm and a width H = 10 mm; the counterweight weighs m = 2.0 kg, and the distance between its center of gravity and the center of the strain gauge is L = 1000 mm. The following calculation example uses only one inclined plate.

[0054] The method for monitoring uneven settlement of a steam turbine foundation in this embodiment specifically includes the following steps:

[0055] 1) Preprocess the collected bending strain data of the inclined plate to eliminate abnormal data caused by external accidental collision.

[0056] Strain gauges are used as data acquisition sensors, which are very sensitive to external interference. The settlement and tilt of the turbine platform are long-term gradual changes, and the amount of change per unit time is very small. Therefore, a low-frequency filtering method is used to pre-process the data. The filtering frequency is set to 0.001Hz to eliminate abnormal signals caused by external interference, such as Figure 2 shown. Figure 2 The picture in the upper middle is the bending strain data signal before processing. Figure 2 The image in the lower middle section shows the processed bending strain data signal.

[0057] 2) According to Hooke's law, the bending stress on the inclined plate is calculated using the following formula:

[0058] σ=E*ε

[0059] Where σ is the bending stress, the elastic modulus E is 201 GPa, and ε is the bending strain, which is 1.13e-4.

[0060] The calculated bending stress is 22.7 MPa.

[0061] 3) Calculate the bending moment using the bending section modulus of the inclined plate and the bending stress formula at the root of the cantilever beam;

[0062] M 弯曲 =σ*W Z

[0063] The flexural section modulus is 8.33e-7m 3 , the calculated bending moment is 18.9N*m.

[0064] 4) Calculate the tilt angle

[0065] M 弯曲 =FL=m*g*cosθ*L

[0066]

[0067] According to the above formula, the calculation formula of the tilt angle is obtained:

[0068]

[0069] According to the above calculation data, the calculated inclination angle is 9.94°, that is, the turbine platform is tilted in one direction at this angle.

[0070] Similarly, the tilt angle of the steam turbine platform in the other direction is obtained, and then the tilt amount of the steam turbine platform is obtained.

[0071] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A monitoring device for uneven settlement of a steam turbine foundation, characterized in that: The monitoring device includes a control unit and an installation base plate, a cylinder, a support plate arranged in the cylinder, an inclined plate, a counterweight block, and a strain sensor. The top of the inclined plate is connected to the support plate, and the bottom of the inclined plate is connected to the counterweight block. The strain sensor is arranged at one end of the inclined plate close to the support plate. The strain sensor is used to collect bending strain data of the inclined plate. The strain sensor is electrically connected to the control unit, and the control unit is used to collect data and perform calculations; the inclined plate includes a first inclined plate and a second inclined plate, and the vertical planes of the first inclined plate and the second inclined plate in the initial state are perpendicular to each other; the counterweight block includes a first counterweight block and a second counterweight block respectively arranged at the lower ends of the first inclined plate and the second inclined plate; the strain sensor includes a first strain sensor and a second strain sensor respectively arranged at the upper ends of the first inclined plate and the second inclined plate.

2. The monitoring device according to claim 1, characterized in that The strain sensor includes a uniaxial strain gauge, and the uniaxial strain gauge is arranged along the length direction of the inclined plate.

3. The monitoring device according to claim 1, characterized in that The monitoring device is installed at one or more positions of the upstream of the high-pressure cylinder or the medium-pressure cylinder, on both sides of the low-pressure cylinder, or on both sides of the generator or the exciter.

4. The monitoring device according to claim 1, characterized in that The cylinder includes an upper cylinder and a lower cylinder, a gasket is arranged between the upper cylinder and the lower cylinder; the bottom of the lower cylinder is fixed to the mounting base; the support plate, inclined plate, counterweight block, and strain sensor are arranged in the lower cylinder.

5. The monitoring device according to claim 4, characterized in that The cylinder is provided with a hole penetrating the wall thickness for vacuuming the cylinder.

6. A method for monitoring uneven settlement of a steam turbine foundation using the monitoring device according to any one of claims 1 to 5, characterized in that: The steps include: The collected bending strain data of the tilted plate are pre-processed to eliminate abnormal data caused by external accidental collision; Calculate the bending stress on the inclined plate; By using the formula of the bending section moment of the inclined plate and the bending stress at the root of the cantilever beam, the inclination angle of the inclined plate corresponding to the bending stress can be reversely calculated, and then the inclination amount of the turbine platform can be obtained; The reverse calculation of the inclination angle of the inclined plate corresponding to the bending stress is performed according to the following formula: M 弯曲 =σ*W Z Where M 弯曲 is the bending moment of the inclined plate at the center line of the strain gauge, σ is the bending stress, W z is the bending section modulus of the inclined plate; at the same time, M 弯曲 =FL=m*g*cosθ*L Where L is the length from the center of gravity of the counterweight to the center line of the strain gauge, θ is the inclination angle of the tilt plate, m is the mass of the counterweight, and g is the acceleration of gravity, which is 9.8 N / Kg. According to the above formula, Then we get the following formula: The inclination angle of the inclined plate is obtained by the above formula; The bending stress on the inclined plate is calculated by the following formula: σ=E*ε Where σ is the bending stress, E is the elastic modulus, and ε is the bending strain.

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