Nuclear power plant steam turbine foundation platform expansion monitoring system and method

Abstract

The invention discloses a nuclear power plant steam turbine foundation platform expansion monitoring system and method. The nuclear power plant steam turbine foundation platform expansion monitoring system comprises a carbon fiber rod device, a zero point measuring plate, a displacement measuring device and a constant temperature device. According to the nuclear power plant turbine foundation platform expansion monitoring system and method, the expansion displacement of the nuclear power plant turbine foundation platform can be measured in real time based on the eddy current displacement sensor, the low-pressure rotor expansion indicating value is corrected according to the real-time measured data, the real expansion amount of the low-pressure rotor is obtained, the expansion indicating value fluctuation phenomenon is solved, and the reliability is improved. And unit power reduction caused by triggering an intervention limit value is avoided.

Description

Technical Field

[0001] The invention relates to the field of nuclear power technology, and in particular to a system and method for monitoring expansion of a steam turbine foundation platform in a nuclear power plant. Background Art

[0002] According to the design documents of the steam turbine manufacturer, in order to ensure that the moving and static parts of the steam turbine do not collide and rub, a low-pressure cylinder rotor absolute expansion monitoring device is designed, and the alarm value and intervention value are set. Because the rotor and the steam turbine foundation shrink asynchronously under the sudden cooling / sudden heating conditions of the steam turbine, the foundation will drive the probe to move, resulting in a deviation in the low-pressure rotor thermal expansion indication. Since this deviation cannot be eliminated, in order to meet the normal operation of the unit, the alarm value of the unit can only be increased. However, if the actual expansion displacement of the low-pressure rotor exceeds the intervention value, there is a risk of wear of the moving and static parts of the steam turbine, which may cause damage to the turbine blades or internal cylinder. To this end, it is necessary to develop a steam turbine foundation platform expansion monitoring device to measure the expansion displacement of the steam turbine platform in real time to correct the low-pressure rotor expansion indication, obtain the actual expansion of the low-pressure rotor, solve the expansion indication fluctuation phenomenon, and avoid false alarms.

[0003] In the field of thermal expansion monitoring of steam turbine foundation platforms, no directly related monitoring methods and reports have been found so far. According to engineering cases in other industries, it is generally achieved by multiplying the length of the concrete structure by the expansion system. Through literature and patent retrieval, there are many studies on the thermal expansion coefficient of concrete and its influencing factors, which can be roughly divided into two categories: model calculation method and experimental method. The main contents are as follows:

[0004] 1) Model calculation method

[0005] Lu Chunpeng and others from Wuhan University conducted a simulation study on the influence of the time-varying thermal expansion coefficient on the temperature stress of concrete. The results showed that the thermal expansion coefficient of concrete changes significantly with the development of age. Yao Wu and others from Tongji University used the orthogonal design test method to study the influence of mix design parameters on the thermal expansion coefficient, and used the efficiency coefficient method to determine the optimal mix ratio that meets multiple indicators. The test results show that the thermal expansion coefficient of concrete increases with the increase of unit water consumption and slurry-to-mass ratio, and the influence of water-cement mass ratio depends on the relative relationship between cement consumption and water consumption. Jiang Kai and others from Three Gorges University used the stress-free gauge measurement values ​​buried in concrete and the corresponding temperature values ​​to perform an inverse analysis of the thermal expansion coefficient of concrete using the least squares method. Tan Kang from Fujian Agriculture and Forestry University pointed out that the thermal expansion of concrete is a dynamic and complex process affected by multiple factors. The experimental data collected on-site at only one instant cannot effectively represent the dynamic change process of thermal expansion.

[0006] 2) Test methods

[0007] The test methods for obtaining the thermal expansion system of concrete include the surface-attached strain gauge method, the laser displacement sensor method, the sampling instrument measurement point method, etc. Among them, the resistance strain gauge method can only obtain the thermal expansion coefficient of the surface, and cannot obtain the relevant parameters inside; the sampling instrument measurement method can only characterize the thermal expansion coefficient of the sampled part, and is greatly affected by the environment; the laser displacement sensor method measures the displacement change before and after the thermal expansion of concrete and then infers the thermal expansion coefficient, but it requires repeated measurements to obtain the coefficient curve under different environmental conditions.

[0008] In summary, the calculation and testing methods of the concrete thermal expansion system have many defects and limitations, and it is impossible to accurately obtain the thermal expansion coefficient in a complex environment. At the same time, considering that there is a gradient change in the temperature field inside the low-pressure cylinder, the thermal expansion displacement of each section of the entire turbine foundation is not uniform, so the method of multiplying the foundation length by the thermal expansion coefficient cannot effectively obtain the accurate value. Summary of the invention

[0009] The technical problem to be solved by the present invention is to provide a system and method for monitoring expansion of a steam turbine foundation platform in a nuclear power plant.

[0010] The technical solution adopted by the present invention to solve the technical problem is: constructing a nuclear power plant steam turbine foundation platform expansion monitoring system, including a carbon fiber rod device, a zero point measurement plate, a displacement measurement device and a constant temperature device;

[0011] The carbon fiber rod device is installed on the foundation platform of the nuclear power plant steam turbine in parallel along the axial direction of the nuclear power plant steam turbine. The carbon fiber rod device includes a plurality of carbon fiber rods connected in sequence. The first end of the first carbon fiber rod is arranged close to the joint bearing seat with zero axial thermal expansion displacement of the first-stage low-pressure cylinder of the nuclear power plant steam turbine; the second end of the last carbon fiber rod is arranged close to the end bearing seat of the second-stage low-pressure cylinder of the nuclear power plant steam turbine;

[0012] The zero point measurement plate is arranged opposite to the second end of the last carbon fiber rod;

[0013] The displacement measuring device comprises an eddy current displacement sensor and a collection device, wherein the collection device is connected to the eddy current displacement sensor, the eddy current displacement sensor is arranged at the end of the second end of the last carbon fiber rod, and the eddy current displacement sensor is arranged opposite to the zero point measurement plate;

[0014] The constant temperature device is connected to the carbon fiber rod device and is used to input a medium into the carbon fiber rod of the carbon fiber rod device to keep the temperature of the carbon fiber rod device constant.

[0015] In some embodiments, the carbon fiber rods are hollow structures, and adjacent carbon fiber rods are connected by connecting pieces, and the material of the connecting pieces is the same as that of the carbon fiber rods.

[0016] In some embodiments, the connecting member is in a round tube structure, the outer diameter of the connecting member is slightly larger than the inner diameter of the carbon fiber rod, and the axial ends of the connecting member are respectively connected to the inner cavities of two adjacent carbon fiber rods.

[0017] In some embodiments, an annular protrusion extends radially outward from the outer side surface of the connecting member, and the outer side surface of the annular protrusion is flush with the inner side surface of the carbon fiber rod.

[0018] In some embodiments, the nuclear power plant steam turbine foundation platform expansion monitoring system further includes a mounting tube, the mounting tube is used to be mounted on the second end of the last carbon fiber rod; the mounting tube includes an end wall and a surrounding wall connected to the end wall, and the eddy current displacement sensor is arranged on the outer side surface of the end wall;

[0019] The surrounding wall is used to be installed in the inner cavity of the second end of the last carbon fiber rod, and the part of the surrounding wall located outside the carbon fiber rod is provided with a first interface part, and the first interface part is used to be connected to the constant temperature device.

[0020] In some embodiments, the nuclear power plant steam turbine foundation platform expansion monitoring system further includes a fixed restraint bracket;

[0021] The fixed restraint bracket is connected to the end of the first end of the first carbon fiber rod, and the fixed restraint bracket includes a first bottom plate and a first support plate vertically connected to the first bottom plate, and the first bottom plate is used to be fixedly connected to the foundation platform of the nuclear power plant steam turbine;

[0022] The opposite sides of the first support plate are respectively provided with a cylindrical portion and a second interface portion, the cylindrical portion is used to be installed in the inner cavity of the first end of the first carbon fiber rod, and the second interface portion is used to be connected to the constant temperature device.

[0023] In some embodiments, the constant temperature device comprises a transmission pipeline, a storage container, a heating radiator and a pressure pump, and the storage container, the heating radiator and the pressure pump are connected to the transmission pipeline;

[0024] Two ends of the transmission pipeline are connected to the first interface part and the second interface part respectively.

[0025] In some embodiments, a first stop valve is provided at one end of the transmission pipeline close to the first interface portion;

[0026] A second stop valve is provided at one end of the transmission pipeline close to the second interface portion.

[0027] In some embodiments, the nuclear power plant steam turbine foundation platform expansion monitoring system further includes a plurality of guide restraint brackets;

[0028] Each of the guide and restraint brackets comprises a second bottom plate and a second support plate vertically connected to the second bottom plate, wherein the second bottom plate is used for fixed connection to the foundation platform of the steam turbine of the nuclear power plant;

[0029] The second supporting plate is provided with an active hole, and the carbon fiber rod is passed through the active hole.

[0030] The present invention also discloses a method for monitoring expansion of a nuclear power plant steam turbine foundation platform, which is applied to a nuclear power plant steam turbine foundation platform expansion monitoring system of any of the above embodiments. The method for monitoring expansion of a nuclear power plant steam turbine foundation platform comprises the following steps:

[0031] Debugging steps: Debugging is performed under cold working conditions of the steam turbine. During the debugging process, the thermostat inputs a medium into the carbon fiber rod of the carbon fiber rod device and maintains the temperature of the medium at 40±2°C. The eddy current displacement sensor obtains the measurement indication D1 of the carbon fiber rod device and the medium temperature value T1; after the thermostat increases the medium temperature by 20°C and the medium temperature is stable, the displacement measuring device obtains the displacement measurement indication D2 of the carbon fiber rod device; the thermal expansion value D3 of the carbon fiber rod device and the displacement measurement difference D4 are calculated. The displacement measurement difference D4 is the difference obtained by subtracting the measurement indication D1 from the displacement measurement indication D2, and the thermal expansion value D3 is compared with the displacement measurement difference D4. If the error is within the required range, the formal test step is performed;

[0032] Formal test steps: confirm that the low-pressure cylinder of the turbine is in a cold state and the medium temperature of the carbon fiber rod of the carbon fiber rod device is constant at 40±2°C, clear the displacement indication of the displacement measuring device, and then the displacement measuring device continuously collects displacement values. After the turbine unit reaches full power, the value displayed by the displacement measuring device is the expansion displacement value of the nuclear power plant turbine foundation platform.

[0033] The implementation of the present invention has the following beneficial effects: the nuclear power plant steam turbine foundation platform expansion monitoring system and method can measure the expansion displacement of the nuclear power plant steam turbine foundation platform in real time based on the eddy current displacement sensor, correct the low-pressure rotor expansion indication according to the real-time measured data, obtain the real expansion amount of the low-pressure rotor, solve the expansion indication fluctuation phenomenon, and avoid the unit power reduction due to triggering the intervention limit. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solution of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work. In the drawings:

[0035] Figure 1 It is one of the structural schematic diagrams of the nuclear power plant steam turbine foundation platform expansion monitoring system in some embodiments of the present invention;

[0036] Figure 2 This is the second structural schematic diagram of the nuclear power plant steam turbine foundation platform expansion monitoring system in some embodiments of the present invention;

[0037] Figure 3 It is the third structural schematic diagram of the nuclear power plant steam turbine foundation platform expansion monitoring system in some embodiments of the present invention;

[0038] Figure 4 is a schematic diagram of the structure of the connecting member in some embodiments of the present invention;

[0039] Figure 5 It is one of the structural schematic diagrams of the installation cylinder in some embodiments of the present invention;

[0040] Figure 6 This is the second structural schematic diagram of the installation cylinder in some embodiments of the present invention;

[0041] Figure 7 is a schematic diagram of the structure of a fixed restraining bracket in some embodiments of the present invention;

[0042] Figure 8 It is a schematic diagram of the structure of the guide and restraint bracket in some embodiments of the present invention. DETAILED DESCRIPTION

[0043] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings, are constructed and operated in a specific direction, and are only for the convenience of describing the present technical solution, rather than indicating that the device or element referred to must have a specific direction, and therefore cannot be understood as a limitation to the present invention.

[0044] It should also be noted that, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected", "fixed", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intermediate elements. The terms "first", "second", "third", etc. are only for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", "third", etc. can explicitly or implicitly include one or more of the features. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0045] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0046] See also Figures 1 to 3 The present invention shows a nuclear power plant steam turbine foundation platform expansion monitoring system, including a carbon fiber rod device 10, a zero point measurement plate 20, a displacement measurement device 30 and a constant temperature device 40.

[0047] The carbon fiber rod device 10 is installed on the foundation platform of the nuclear power plant steam turbine in parallel along the axial direction of the nuclear power plant steam turbine. The carbon fiber rod device 10 includes a plurality of carbon fiber rods 11 connected in sequence, and all the carbon fiber rods 11 are coaxially arranged. The first end of the first carbon fiber rod 11 is arranged near the joint bearing seat with zero axial thermal expansion displacement of the first-stage low-pressure cylinder of the nuclear power plant steam turbine (i.e., the dead point, No. 2 bearing), and the second end of the last carbon fiber rod 11 is arranged near the end bearing seat (No. 4 bearing seat) of the second-stage low-pressure cylinder of the nuclear power plant steam turbine. Preferably, the thermal expansion coefficient of the carbon fiber rod 11 is ±1e -6 / ℃ carbon fiber rod, thermal expansion coefficient, appears in the form of a ratio. The cross-sectional diameter of the carbon fiber rod 11 is 35mm, and the combined length of multiple carbon fiber rods 11 is about 24m (i.e., the combined length of two low-pressure cylinders of the steam turbine), and they are installed parallel to the axial direction of the nuclear power plant steam turbine on the foundation platform of the nuclear power plant steam turbine. Preferably, the number of the carbon fiber rods 11 can be two or three, and the number and length can be selected and set according to actual needs, and are not specifically limited here.

[0048] In some embodiments, the carbon fiber rod 11 is a hollow structure, and adjacent carbon fiber rods 11 are connected by a connector 12, and the material of the connector 12 is the same as that of the carbon fiber rod 11. The carbon fiber rod 11 and the connector 12 may be interference fit. Figure 4 As shown, the connector 12 is a round tube structure, the outer diameter of the connector 12 is slightly larger than the inner diameter of the carbon fiber rod 11, and the axial ends of the connector 12 are respectively connected to the inner cavities of two adjacent carbon fiber rods 11. An annular protrusion 121 extends radially outward from the outer side of the connector 12, and the outer side of the annular protrusion 121 is flush with the inner side of the carbon fiber rod 11. The end faces of the two adjacent carbon fiber rods 11 abut against the end face of the annular protrusion 121.

[0049] like Figure 1 , Figure 2 , Figure 3 , Figure 5 and Figure 6 As shown, in some embodiments, the nuclear power plant turbine foundation platform expansion monitoring system also includes a mounting tube 50, which is used to be installed on the second end of the last carbon fiber rod 11, and the mounting tube 50 includes an end wall 51 and a surrounding wall 52 connected to the end wall 51, and the eddy current displacement sensor 31 is arranged on the outer surface of the end wall 51.

[0050] The surrounding wall 52 is used to be installed in the inner cavity of the second end of the last carbon fiber rod 11, and the two can be interference fit. The part of the surrounding wall 52 located outside the carbon fiber rod 11 is provided with a first interface portion 53, and the first interface portion 53 is used to connect with the constant temperature device 40. Of course, the surrounding wall 52 can also be used to be installed on the outer periphery of the second end of the last carbon fiber rod 11.

[0051] Figure 5 and Figure 6 As shown, in some embodiments, an isolation portion 521 is provided on the periphery of the surrounding wall 52, and the isolation portion 521 defines a first portion and a second portion of the surrounding wall 52, the first portion is connected to the second end of the last carbon fiber rod 11, and the first interface portion 53 is provided on the second portion.

[0052] In some embodiments, Figure 7As shown, the nuclear power plant steam turbine foundation platform expansion monitoring system further includes a fixed restraint bracket 60. The fixed restraint bracket 60 is connected to the end of the first end of the first carbon fiber rod 11 to limit the axial and radial displacement of the carbon fiber rod 11.

[0053] The fixed restraining bracket 60 includes a first bottom plate 61 and a first supporting plate 62 vertically connected to the first bottom plate 61 . The first bottom plate 61 is used for fixed connection with the foundation platform of the steam turbine of the nuclear power plant.

[0054] The first support plate 62 has a cylindrical portion 63 and a second interface portion 64 on opposite sides thereof. The cylindrical portion 63 is used to be installed in the inner cavity of the first end of the first carbon fiber rod 11 , and the two are interference fit. The second interface portion 64 is used to be connected to the thermostat 40 .

[0055] In some embodiments, Figure 8 As shown, the nuclear power plant steam turbine foundation platform expansion monitoring system further includes a plurality of guide constraint brackets 70, and the guide constraint brackets 70 are used to enable the carbon fiber rods 11 to move freely in the axial direction as the nuclear power plant steam turbine foundation platform expands.

[0056] Furthermore, the number of the guiding restraining brackets 70 can be two, three, four, five, six or seven. Preferably, the number of the guiding restraining brackets 70 is seven, one of which is installed about 10 cm upstream of the end (end point) of the second end of the last carbon fiber rod 11, and the remaining guiding restraining brackets 70 (which can be the remaining six guiding restraining brackets 70) are evenly arranged between the first end of the first carbon fiber rod 11 and the second end of the last carbon fiber rod 11 (i.e., between the starting point and the end point), so that the carbon fiber rod 11 can move freely in the axial direction as the foundation platform of the nuclear power plant turbine expands.

[0057] Each of the guide and restraint brackets 70 includes a second base plate 71 and a second support plate 72 vertically connected to the second base plate 71. The second base plate 71 is used to be fixedly connected to the foundation platform of the nuclear power plant steam turbine. The second base plate 71 may be provided with a plurality of bolt holes so that it can be installed on the foundation platform of the nuclear power plant steam turbine by bolts.

[0058] The second support plate 72 is provided with an active hole 721, and the carbon fiber rod 11 is inserted into the active hole 721. The active hole 721 may be a circular hole, and the inner diameter of the active hole 721 is slightly larger than the outer diameter of the carbon fiber rod 11. For example, the inner diameter of the active hole 721 may be 40 mm, while the outer diameter of the carbon fiber rod 11 is 35 mm. In addition, a double trumpet-shaped polytetrafluoroethylene gasket with a thickness of 2 mm is installed along the hole diameter of the guide and restraint bracket 70 to reduce the sliding friction coefficient.

[0059] like Figure 1 and Figure 2 As shown, in some embodiments, the zero point measurement plate 20 is arranged opposite to the second end of the last carbon fiber rod 11. The zero point measurement plate 20 is made of carbon steel material and has an L-shaped structure or a T-shaped structure. The bottom plate size of the zero point measurement plate 20 is 20cm*10cm*2cm, and there are 4 bolt holes for installing bolts; the vertical plate size of the zero point measurement plate 20 is 20cm*20cm*1cm, and the surface finish is level 4. The zero point measurement plate 20 is installed on the foundation below the No. 4 bearing seat, and the vertical inclination angle is ≤5°. Preferably, the zero point measurement plate 20 should be installed parallel to the original eddy current displacement sensor bracket. Considering the additional eddy current length and measurement gap of the guide constraint near the No. 4 bearing seat, the zero point measurement plate 20 should be close to the guide constraint bracket 70 of the last carbon fiber rod 11.

[0060] like Figure 1 As shown, in some embodiments, the displacement measuring device 30 includes an eddy current displacement sensor 31 and a collection device 32, the collection device 32 is connected to the eddy current displacement sensor 31, the eddy current displacement sensor 31 is arranged at the end of the second end of the last carbon fiber rod 11, and the eddy current displacement sensor 31 is arranged opposite to the zero point measurement plate 20. Among them, the eddy current displacement sensor 31 can be used to detect displacement data, temperature data, etc. The sensitive direction of the eddy current displacement sensor 31 is consistent with the axis of the carbon fiber rod 11, and is installed at the end (end position) of the second end of the last carbon fiber rod 11. The collection device 32 can continuously record the data of the eddy current displacement sensor 31 and display the value in real time. The eddy current displacement sensor 31 has a measurement accuracy of 0.01mm, and the range of the eddy current displacement sensor 31 should be a large range. In order to avoid measurement errors introduced by equipment performance differences, the eddy current displacement sensor 31 can meet the full range measurement of the steam turbine platform from cold to hot. The eddy current displacement sensor 31 should be selected from the same model or eddy current displacement sensor with similar performance as the original monitoring system of the nuclear power plant steam turbine to avoid measurement errors. The acquisition equipment 32 includes but is limited to industrial computers.

[0061] like Figure 3 As shown, the thermostat 40 is connected to the carbon fiber rod device 10, and is used to input a medium into the carbon fiber rod 11 of the carbon fiber rod device 10, so that the temperature of the carbon fiber rod device 10 is kept constant. The thermostat 40 includes a transmission pipeline 41, a storage container 42, a heating radiator 43 and a pressure pump 44. The storage container 42, the heating radiator 43 and the pressure pump 44 are connected to the transmission pipeline 41, and the transmission pipeline 41 can be a transmission hose (Φ10mm).

[0062] The two ends of the transmission pipeline 41 are connected to the first carbon fiber rod 11 and the last carbon fiber rod 11, respectively. Preferably, the two ends of the transmission pipeline 41 can be connected to the first interface 53 and the second interface 64, respectively. The heating radiator 43 is used to maintain the medium temperature constant, and the pressure pump 44 provides a constant pressure (0.1MPa) for the medium to promote the flow of the medium. At the same time, a flexible insulation coat can be laid on the surface of the transmission pipeline 41 and the carbon fiber rod 11 to maintain the medium temperature at 40±2℃.

[0063] The positions of the storage container 42, the heating radiator 43 and the pressure pump 44 can be adjusted appropriately according to actual needs. In addition, at least one temperature sensor and at least one pressure sensor can be provided on the transmission pipeline 41. The temperature sensor can be used to detect the temperature of the medium, and the pressure sensor can be used to detect the pressure of the medium.

[0064] Furthermore, a first stop valve 45 is provided at one end of the transmission pipeline 41 close to the first interface portion 53 , and a second stop valve 46 is provided at one end of the transmission pipeline 41 close to the second interface portion 64 .

[0065] In some embodiments, the carbon fiber rod 11 is filled with a constant temperature medium, and the medium is in a slow flow state. The constant temperature device 40 is used to ensure that the medium temperature is constant and the pressure difference is constant, so as to ensure that the temperature of the carbon fiber rod 11 remains constant and avoid measurement deviation caused by the introduction of temperature difference.

[0066] In some embodiments, the nuclear power plant steam turbine foundation platform expansion monitoring system can measure the expansion displacement of the nuclear power plant steam turbine foundation platform in real time based on the eddy current displacement sensor 31, correct the low-pressure rotor expansion indication according to the real-time measurement data, obtain the true expansion of the low-pressure rotor, solve the expansion indication fluctuation phenomenon, and avoid unit power reduction due to triggering the intervention limit.

[0067] The present invention also discloses a method for monitoring expansion of a nuclear power plant steam turbine foundation platform, which is applied to the nuclear power plant steam turbine foundation platform expansion monitoring system of the above embodiment. The method for monitoring expansion of a nuclear power plant steam turbine foundation platform comprises the following steps:

[0068] Debugging steps: Debugging is performed under cold working conditions of the steam turbine. During the debugging process, the thermostat 40 inputs a medium into the carbon fiber rod 11 of the carbon fiber rod device 10, and maintains the temperature of the medium at 40±2°C. The eddy current displacement sensor 31 obtains the measurement indication D1 (initial value) and the medium temperature value T1 of the carbon fiber rod device 10; after the thermostat 40 increases the medium temperature by 20°C and the medium temperature is stable, the displacement measuring device 30 obtains the displacement measurement indication D2 (value after expansion) of the carbon fiber rod device 10; the thermal expansion value D3 of the carbon fiber rod device 10 is calculated (which can be calculated according to the thermal expansion formula: 20°C×24m×1e-6 / ℃) and calculate the displacement measurement difference D4, which is the difference between the displacement measurement indication D2 and the measurement indication D1, and compare the thermal expansion value D3 with the displacement measurement difference D4 (displacement measurement indication D2-measurement indication D1). If the error is within the required range (the error is within the required range, that is, less than or equal to 5%), the formal test steps are carried out;

[0069] Formal test steps: confirm that the low-pressure cylinder of the steam turbine is in a cold state and the medium temperature of the carbon fiber rod 11 of the carbon fiber rod device is constant at 40±2°C, reset the displacement indication of the displacement measuring device 30 to zero, and then the displacement measuring device 30 continuously collects displacement values. After the steam turbine unit reaches full power, the value displayed by the displacement measuring device 30 is the expansion displacement value of the nuclear power plant turbine foundation platform.

[0070] Specifically, the expansion monitoring system of the steam turbine foundation platform of this nuclear power plant is installed and debugged under the cold working condition of the steam turbine. During the debugging process, the medium temperature is first maintained at 40±2℃, and the measured value D1 and the medium temperature value T1 of the displacement measuring device 30 are recorded; then the medium temperature is increased by 20℃ by the constant temperature device 40, and the displacement measurement value D2 is recorded after stabilization; the thermal expansion formula is applied ( 20℃×24m×1e -6 / ℃ ) The thermal expansion value D3 of the carbon fiber rod 11 is calculated and compared with the displacement measurement difference D4 (D2-D1). If the error exceeds the required range (i.e., greater than 5%), the expansion monitoring system of the nuclear power plant turbine foundation platform is re-debugged. If the error is within the required range, i.e., less than or equal to 5%, the formal test steps are carried out.

[0071] Formal test steps: During the formal test, confirm that the low-pressure cylinder of the steam turbine is in a cold state and the medium temperature is constant at 40±2℃, reset the displacement indication value by the acquisition equipment preset method, and start to continuously collect displacement values. After the unit reaches full power, the value displayed by the displacement measurement device 30 is the expansion displacement value of the nuclear power plant steam turbine foundation platform.

[0072] It can be understood that the expansion monitoring method of the nuclear power plant turbine foundation platform can measure the expansion displacement of the nuclear power plant turbine foundation platform, correct the low-pressure rotor expansion indication according to the real-time measurement data, obtain the actual expansion of the low-pressure rotor, solve the expansion indication fluctuation phenomenon, and avoid unit power reduction due to triggering the intervention limit.

[0073] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the scope covered by the claims of the present invention.

Claims

1. A nuclear power plant steam turbine foundation platform expansion monitoring system, characterized in that: It comprises a carbon fiber rod device (10), a zero point measurement plate (20), a displacement measurement device (30) and a constant temperature device (40); The carbon fiber rod device (10) is installed on the foundation platform of the nuclear power plant steam turbine in parallel along the axial direction of the nuclear power plant steam turbine, and the carbon fiber rod device (10) comprises a plurality of carbon fiber rods (11) connected in sequence, wherein the first end of the first carbon fiber rod (11) is arranged close to a joint bearing seat with zero axial thermal expansion displacement of a first-stage low-pressure cylinder of the nuclear power plant steam turbine; and the second end of the last carbon fiber rod (11) is arranged close to a terminal bearing seat of a second-stage low-pressure cylinder of the nuclear power plant steam turbine; The zero point measurement plate (20) is arranged opposite to the second end of the last carbon fiber rod (11); The displacement measuring device (30) comprises an eddy current displacement sensor (31) and a collection device (32), wherein the collection device (32) is connected to the eddy current displacement sensor (31), the eddy current displacement sensor (31) is arranged at the end of the second end of the last carbon fiber rod (11), and the eddy current displacement sensor (31) is arranged opposite to the zero point measurement plate (20); The constant temperature device (40) is connected to the carbon fiber rod device (10) and is used to input a medium into the carbon fiber rod (11) of the carbon fiber rod device (10) so as to keep the temperature of the carbon fiber rod device (10) constant.

2. The nuclear power plant steam turbine foundation platform expansion monitoring system according to claim 1, characterized in that: The carbon fiber rods (11) are of a hollow structure, and adjacent carbon fiber rods (11) are connected via a connecting piece (12), and the material of the connecting piece (12) is the same as that of the carbon fiber rods (11).

3. The nuclear power plant steam turbine foundation platform expansion monitoring system according to claim 2, characterized in that: The connecting piece (12) is in the form of a circular tube structure, the outer diameter of the connecting piece (12) is slightly larger than the inner diameter of the carbon fiber rod (11), and the axial ends of the connecting piece (12) are respectively connected to the inner cavities of two adjacent carbon fiber rods (11).

4. The nuclear power plant steam turbine foundation platform expansion monitoring system according to claim 2, characterized in that: An annular protrusion (121) is radially extended outward on the outer side surface of the connecting member (12), and the outer side surface of the annular protrusion (121) is flush with the inner side surface of the carbon fiber rod (11).

5. The nuclear power plant steam turbine foundation platform expansion monitoring system according to claim 1, characterized in that: The nuclear power plant steam turbine foundation platform expansion monitoring system further comprises a mounting tube (50), wherein the mounting tube (50) is used to be mounted on the second end of the last carbon fiber rod (11); the mounting tube (50) comprises an end wall (51) and a surrounding wall (52) connected to the end wall (51), and the eddy current displacement sensor (31) is arranged on the outer side surface of the end wall (51); The surrounding wall (52) is used to be installed in the inner cavity of the second end of the last carbon fiber rod (11), and the part of the surrounding wall (52) located outside the carbon fiber rod (11) is provided with a first interface part (53), and the first interface part (53) is used to be connected to the constant temperature device (40).

6. The nuclear power plant steam turbine foundation platform expansion monitoring system according to claim 5, characterized in that: The nuclear power plant steam turbine foundation platform expansion monitoring system further comprises a fixed restraint bracket (60); The fixed restraint bracket (60) is connected to the end of the first end of the first carbon fiber rod (11), and the fixed restraint bracket (60) comprises a first bottom plate (61) and a first support plate (62) vertically connected to the first bottom plate (61), and the first bottom plate (61) is used for fixed connection with the foundation platform of the steam turbine of the nuclear power plant; The opposite sides of the first support plate (62) are respectively provided with a cylindrical portion (63) and a second interface portion (64), wherein the cylindrical portion (63) is used to be installed in the inner cavity of the first end of the first carbon fiber rod (11), and the second interface portion (64) is used to be connected to the constant temperature device (40).

7. The nuclear power plant steam turbine foundation platform expansion monitoring system according to claim 6, characterized in that: The constant temperature device (40) comprises a transmission pipeline (41), a storage container (42), a heating radiator (43) and a pressure pump (44), wherein the storage container (42), the heating radiator (43) and the pressure pump (44) are connected to the transmission pipeline (41); Both ends of the transmission pipeline (41) are connected to the first interface part (53) and the second interface part (64) respectively.

8. The nuclear power plant steam turbine foundation platform expansion monitoring system according to claim 7, characterized in that: A first stop valve (45) is provided at one end of the transmission pipeline (41) close to the first interface portion (53); A second stop valve (46) is provided at one end of the transmission pipeline (41) close to the second interface portion (64).

9. The nuclear power plant steam turbine foundation platform expansion monitoring system according to claim 1, characterized in that: The nuclear power plant steam turbine foundation platform expansion monitoring system further comprises a plurality of guide restraint brackets (70); Each of the guide and restraint brackets (70) comprises a second bottom plate (71) and a second support plate (72) vertically connected to the second bottom plate (71), wherein the second bottom plate (71) is used for being fixedly connected to a foundation platform of a steam turbine of a nuclear power plant; The second support plate (72) is provided with a movable hole (721), and the carbon fiber rod (11) is inserted into the movable hole (721).

10. A method for monitoring expansion of a nuclear power plant steam turbine foundation platform, applied to the nuclear power plant steam turbine foundation platform expansion monitoring system according to any one of claims 1 to 9, characterized in that: The method for monitoring expansion of a nuclear power plant steam turbine foundation platform comprises the following steps: Debugging steps: debugging is performed under cold working conditions of the steam turbine. During the debugging process, the thermostat (40) inputs a medium into the carbon fiber rod (11) of the carbon fiber rod device and maintains the temperature of the medium at 40±2°C. The eddy current displacement sensor (31) obtains the measurement indication D1 of the carbon fiber rod device (10) and the medium temperature value T1. After the thermostat (40) increases the medium temperature by 20°C and the medium temperature is stable, the displacement measuring device (30) obtains the displacement measurement indication D2 of the carbon fiber rod device (10). The thermal expansion value D3 of the carbon fiber rod device (10) and the displacement measurement difference D4 are calculated. The displacement measurement difference D4 is the difference obtained by subtracting the measurement indication D1 from the displacement measurement indication D2. The thermal expansion value D3 is compared with the displacement measurement difference D4. If the error is within the required range, a formal test step is performed. Formal test steps: confirm that the low-pressure cylinder of the steam turbine is in a cold state and the medium temperature of the carbon fiber rod (11) of the carbon fiber rod device is constant at 40±2° C., clear the displacement indication of the displacement measuring device (30), and then the displacement measuring device (30) continuously collects displacement values. After the steam turbine unit reaches full power, the value displayed by the displacement measuring device (30) is the expansion displacement value of the nuclear power plant steam turbine foundation platform.

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