Fiber bragg grating strain sensor for heat transfer pipeline of heat exchanger of nuclear power plant

Abstract

The utility model discloses a fiber bragg grating strain sensor for a heat transfer pipeline of a heat exchanger of a nuclear power plant. The fiber bragg grating strain sensor comprises a packaging shell and an optical fiber assembly installed on the packaging shell. The fiber bragg grating strain sensor for the heat transfer pipeline of the nuclear power plant heat exchanger can be installed on the heat transfer pipeline of the nuclear power plant heat exchanger to realize strain measurement of the heat transfer pipeline of the heat exchanger, and can integrally cover the heat transfer pipeline of the heat exchanger of the nuclear power plant by arranging the packaging shell; the coverage area is remarkably increased compared with that of a traditional single sensor, so that the steam scouring resistance is remarkably improved, the two fiber gratings are arranged, strain data of two different measuring points of the heat transfer pipeline of the heat exchanger of the nuclear power plant can be tested at the same time, and the single sensor is prevented from being directly exposed in a steam scouring environment. And the relative position of the measurement areas of the two fiber gratings is accurately determined by the position size of the positioning groove on the packaging shell, so that the personal error in the installation process is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to nuclear power plant heat exchanger heat pipeline vibration test field especially, and it relates to a kind of nuclear power plant heat exchanger heat pipeline fiber grating strain sensor. BACKGROUND

[0002] In recent years, nuclear power unit has occurred several times in China due to heat exchanger heat pipe cracking, resulting in unplanned shutdown event of unit, which has brought serious influence to the safe and economic operation of related nuclear power plant. According to the event analysis report, vibration fatigue is an important reason for the cracking of heat pipe, so direct strain measurement of heat pipe under working condition is the most effective means to evaluate the safety of heat exchanger.

[0003] Since the heat pipe is located inside the heat exchanger, the installation of the strain sensor is usually limited to the unit overhaul period, and it must be stably operated to the next maintenance cycle. During this period, the sensor needs to withstand the continuous impact of high-speed steam, and it is difficult to maintain. At the same time, in order to avoid affecting the heat pipe, the sensor must not produce metal foreign matter. In view of these challenges, the requirements for strain testing technology are extremely strict. Fiber grating strain testing technology has become an effective method for monitoring the strain of heat exchanger heat pipe due to its excellent waterproof performance, simple and reliable installation and low foreign matter risk of non-metallic material, and has been successfully applied in domestic nuclear power plants.

[0004] According to the implementation experience of fiber grating strain testing technology in nuclear heat exchanger heat pipe strain testing, the fiber grating strain sensor currently used has the following problems to be improved: a single fiber grating strain sensor can only obtain single-point strain data. In order to accurately obtain the motion trajectory of the heat pipe, one sensor needs to be installed at each of the two measuring points on the pipeline, but the measuring point selection cannot avoid the steam scouring surface, which easily causes some sensors to fail prematurely due to strong steam scouring, the installation space of the sensor on site is small, which leads to low construction efficiency when installing the sensor on the same section of titanium pipe. Due to the small installation space, it is difficult to control the bending radius when bending the optical fiber on the titanium pipe, two optical fibers need to be used for two measuring points, which increases the construction workload and increases the risk of strain sensor and optical fiber loosening due to steam scouring. UTILITY MODEL CONTENTS

[0005] The technical problem to be solved by the utility model is to provide a fiber grating strain sensor for nuclear power plant heat exchanger heat pipeline.

[0006] The technical scheme adopted by the utility model to solve its technical problem is: a fiber grating strain sensor for nuclear power plant heat exchanger heat pipeline is constructed, which comprises an encapsulation shell and an optical fiber assembly installed on the encapsulation shell.

[0007] The packaging shell is provided with a first positioning groove, a second positioning groove, a third positioning groove, a fourth positioning groove and a fifth positioning groove connected in sequence, and the second positioning groove and the fourth positioning groove are arranged in parallel.

[0008] The optical fiber assembly comprises a first tail fiber, a first fiber grating, a second tail fiber, a second fiber grating and a third tail fiber connected in sequence, and the first fiber grating and the second fiber grating are used for sensing the strain of the heat transfer pipeline of the heat exchanger.

[0009] The first tail fiber is mounted on the first positioning groove, the first fiber grating is mounted on the second positioning groove, the second tail fiber is mounted on the third positioning groove, the second fiber grating is mounted on the fourth positioning groove, and the third tail fiber is mounted on the fifth positioning groove.

[0010] In some embodiments, the second positioning groove and the fourth positioning groove are each provided with a first glue injection hole and a pair of first action holes, and the pair of first action holes are separately located on the two sides of the first glue injection hole.

[0011] In some embodiments, the packaging shell is provided with a first adhesive part and a second adhesive part, the first adhesive part and the second adhesive part are each provided with an adhesive part, and the first adhesive part and the second adhesive part are each provided with a through hole.

[0012] In some embodiments, the number of the first adhesive part and the second adhesive part is two, the two first adhesive parts are separately located on the two sides of the second positioning groove, and the two second adhesive parts are separately located on the two sides of the fourth positioning groove.

[0013] In some embodiments, the packaging shell is provided with a first glue injection groove and a second glue injection groove, the first glue injection groove is arranged along the circumferential direction of the first adhesive part, and the second glue injection groove is arranged along the circumferential direction of the second adhesive part.

[0014] The first glue injection groove and the second glue injection groove are each provided with a plurality of second glue injection holes and a plurality of second action holes.

[0015] In some embodiments, the packaging shell is provided with a third glue injection groove, and the third glue injection groove is located at the middle position between the first glue injection groove and the second glue injection groove.

[0016] In some embodiments, the third glue injection groove is provided with a third glue injection hole and a pair of third action holes, and the pair of third action holes are separately located on the two sides of the third glue injection hole.

[0017] In some embodiments, the packaging shell is provided with a plurality of positioning holes, and the plurality of positioning holes are located at the four corner positions of the packaging shell.

[0018] In some embodiments, the fifth positioning groove is arranged obliquely relative to the first positioning groove, and a distance between the fifth positioning groove and the first positioning groove gradually decreases in a direction of the second positioning groove towards the first positioning groove.

[0019] In some embodiments, a difference between the reflection center wavelengths of the first fiber grating and the second fiber grating is greater than or equal to 5 nm.

[0020] The nuclear power plant heat exchanger heat pipeline fiber grating strain sensor can be installed on the nuclear power plant heat exchanger heat pipeline, realizes strain measurement of the heat exchanger heat pipeline, the packaging shell is arranged, the nuclear power plant heat exchanger heat pipeline fiber grating strain sensor can be integrally covered on the nuclear power plant heat exchanger heat pipeline, the covering area is significantly increased than that of a traditional single sensor, so that the ability of resisting steam scouring is significantly improved, two fiber gratings are arranged, strain data of two different measuring points of the nuclear power plant heat exchanger heat pipeline can be tested at the same time, a single sensor is directly exposed to a steam scouring environment is avoided, and the relative position of the measurement areas of the two fiber gratings is accurately determined by the position and size of the positioning groove on the packaging shell, so that human error in the installation process is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical scheme of the utility model, the utility model will be further described below in combination with the drawings and embodiments, and it should be understood that the following drawings only show some embodiments of the utility model, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor. In the drawings:

[0022] Fig. 1 It is the overall structure schematic diagram of the nuclear power plant heat exchanger heat pipeline fiber grating strain sensor in some embodiments of the utility model;

[0023] Fig. 2 It is the structure schematic diagram of the packaging shell in some embodiments of the utility model;

[0024] Fig. 3 It is the structure schematic diagram of the fiber assembly in some embodiments of the utility model. DETAILED DESCRIPTION

[0025] In order to have a clearer understanding of the technical features, objects and effects of the present application, the specific embodiments of the present application will be described in detail with reference to the drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "upper", "lower", "left", "right", "vertical", "horizontal", "vertical", "horizontal", "top", "bottom", "inner", "outer", "head", "tail" and the like are based on the directions or positional relationships shown in the drawings, constructed and operated in a particular direction, and are only for the convenience of describing the present technical solution, and do not indicate that the devices or elements indicated must have a particular direction, so it cannot be understood as a limitation of the present application.

[0026] It should be further pointed out that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing", "setting" and the like should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements or the interaction relationship between two elements. When an element is referred to as "on" or "below" another element, the element can be "directly" or "indirectly" above the other element, or there can be one or more intervening elements. The terms "first", "second", "third" and the like 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 indicated technical features, therefore, the features with "first", "second", "third" and the like can be explicitly or implicitly include one or more such features. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0027] Please refer to Figs. 1 to 3The utility model provides a kind of nuclear power plant heat exchanger heat transfer pipeline fiber grating strain sensor in some embodiments of the utility model, it includes encapsulation shell 1 and the optical fiber assembly 2 being installed on encapsulation shell 1.Optical fiber assembly 2 includes the first tail fiber 21, the first fiber grating 22, the second tail fiber 23, the second fiber grating 24 and the third tail fiber 25 being connected in sequence, and the first fiber grating 22 and the second fiber grating 24 are used to respond the strain of heat exchanger heat transfer pipeline;The first tail fiber 21 is installed on the first positioning groove 11, the first fiber grating 22 is installed on the second positioning groove 12, the second tail fiber 23 is installed on the third positioning groove 13, the second fiber grating 24 is installed on the fourth positioning groove 14, and the third tail fiber 25 is installed on the fifth positioning groove 15.Fiber grating is a kind of optical element using the periodic variation of refractive index of optical fiber material to reflect specific wavelength light, and can be applied to strain sensor.

[0028] Understandably, the nuclear power plant heat exchanger heat transfer pipeline fiber grating strain sensor can be installed on the nuclear power plant heat exchanger heat transfer pipeline to measure the strain of the heat exchanger heat transfer pipeline, and the nuclear power plant heat exchanger heat transfer pipeline fiber grating strain sensor can be covered on the nuclear power plant heat exchanger heat transfer pipeline as a whole by arranging the encapsulation shell 1, so that the coverage area is significantly increased compared with a traditional single sensor, thereby significantly improving the ability to resist steam scouring, and the two fiber gratings can simultaneously test the strain data of two different measuring points of the nuclear power plant heat exchanger heat transfer pipeline, avoiding direct exposure of the single sensor to the steam scouring environment, and ensuring that the relative positions of the measurement areas of the two fiber gratings are accurately determined by the positions and sizes of the positioning grooves on the encapsulation shell 1, thereby reducing human errors during installation.

[0029] More specifically, the third positioning groove 13 is arc-shaped, the second positioning groove 12 and the fourth positioning groove 14 are separately located on the two sides of the third positioning groove 13, and the second tail fiber 23 is bent at the third positioning groove 13.The fifth positioning groove 15 is inclined relative to the first positioning groove 11, and the distance between the fifth positioning groove 15 and the first positioning groove 11 gradually decreases in the direction from the second positioning groove 12 to the first positioning groove 11, i.e., the inlet end and the outlet end of the optical fiber assembly 2 are located at the same position, which avoids signal loss caused by bending the optical fiber during installation and significantly improves installation efficiency.In addition, the difference between the reflection center wavelengths of the first fiber grating 22 and the second fiber grating 24 is greater than or equal to 5nm, so that the first fiber grating 22 and the second fiber grating 24 can be easily distinguished according to different reflection center wavelengths.

[0030] Further, the second positioning groove 12 and the fourth positioning groove 14 are both provided with a first glue injection hole 31 and a pair of first action holes 32, and the pair of first action holes 32 are separately located on the two sides of the first glue injection hole 31. It can be understood that after the first fiber grating 22 and the second fiber grating 24 are pre-stretched, the first fiber grating 22 can be installed on the second positioning groove 12, and the second fiber grating 24 can be installed on the fourth positioning groove 14, and by injecting glue from the first glue injection hole 31, the two ends of the first fiber grating 22 and the second fiber grating 24 are fixed on the corresponding positioning grooves, so as to complete the relative fixation of the fiber grating and the packaging shell 1, that is, the two ends of the fiber grating can be fixed on the two ends of the corresponding positioning groove by the glue, and the main body part of the first fiber grating 22 and the second fiber grating 24 remains suspended. In addition, since the outer diameter of the tail fiber is larger than the outer diameter of the fiber grating, the main body part of the first fiber grating 22 and the second fiber grating 24 remains suspended, and the glue flows to the tail fiber, so as to fix the tail fiber on the corresponding positioning groove. And the first action hole 32 is separately provided on the two sides of the first glue injection hole 31, which can be used for exhaust and checking whether the glue is completely filled. In addition, the distance between the second positioning groove 12 and the fourth positioning groove 14 is preferably 1 / 4 of the circumference of the measured pipeline.

[0031] As shown in Fig. 2 The packaging shell 1 is provided with a first adhesive part 16 and a second adhesive part 17, the first adhesive part 16 and the second adhesive part 17 are both provided with an adhesive, and the first adhesive part 16 and the second adhesive part 17 are both provided with a through hole 18. The number of the first adhesive part 16 and the second adhesive part 17 is two, the two first adhesive parts 16 are separately located on the two sides of the second positioning groove 12, and the two second adhesive parts 17 are separately located on the two sides of the fourth positioning groove 14. Specifically, the upper surfaces of the first adhesive part 16 and the second adhesive part 17 are flush with the upper surface of the packaging shell 1, the adhesive can be double-sided tape, which is used to provide preliminary fixation when the nuclear power plant heat exchanger pipeline fiber grating strain sensor is installed on the heat exchanger pipeline, and maintain the preset tension of the fiber grating, and the through hole 18 is provided, so that when the double-sided tape fails, the instant adhesive can be injected for fixation, and the preset tension of the fiber grating can be maintained.

[0032] The first glue injection groove 101 is arranged along the circumferential direction of the first adhesive part 16, and the second glue injection groove 102 is arranged along the circumferential direction of the second adhesive part 17. The first glue injection groove 101 and the second glue injection groove 102 are both provided with a plurality of second glue injection holes 33 and a plurality of second action holes 34. The packaging shell 1 is provided with a third glue injection groove 103, which is located at the middle position between the first glue injection groove 101 and the second glue injection groove 102. The third glue injection groove 103 is provided with a third glue injection hole 35 and a pair of third action holes 36, which are separately located on both sides of the third glue injection hole 35. The above-mentioned second action holes 34 are separately arranged on both sides of the second glue injection hole 33. It can be understood that before the nuclear power plant heat exchanger heat pipe fiber grating strain sensor is installed on the heat exchanger heat pipe, a layer of AB glue needs to be brushed on the other bonding surface except the first adhesive part 16 and the second adhesive part 17. If the AB glue touches the first fiber grating 22 or the second fiber grating 24, it may cause functional failure, and the glue injection groove can effectively isolate the influence of the AB glue. After the heat exchanger heat pipe completes the preliminary fixation of the nuclear power plant heat exchanger heat pipe fiber grating strain sensor, the glue is injected into the glue injection groove through the above-mentioned glue injection hole, so as to firmly fix the nuclear power plant heat exchanger heat pipe fiber grating strain sensor and the heat exchanger heat pipe. Compared with directly brushing glue on the bonding surface, this way provides higher bonding reliability.

[0033] Further, the packaging shell 1 is provided with a plurality of positioning holes 19 located at the four corner positions of the packaging shell 1 to adapt to the arc surface of the heat exchanger heat pipe. When installing the nuclear power plant heat exchanger heat pipe fiber grating strain sensor, instant glue can be injected through the positioning hole 19 to fix the nuclear power plant heat exchanger heat pipe fiber grating strain sensor, so that the nuclear power plant heat exchanger heat pipe fiber grating strain sensor is closely attached to the surface of the heat exchanger heat pipe.

[0034] It can be understood that the above embodiments only express the preferred embodiments of the present application, which are described in detail and specifically, but cannot be understood as a limitation on the scope of the present application. It should be noted that for ordinary skilled persons in the art, the above technical features can be freely combined without departing from the concept of the present application, and some modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, any equivalent transformation and modification within the scope of the claims of the present application shall belong to the scope of the claims of the present application.

Claims

1. A nuclear power plant heat exchanger heat transfer tube fiber grating strain sensor, characterized in that, The package shell (1) and the optical fiber assembly (2) are arranged on the package shell (1). The package shell (1) is provided with a first positioning groove (11), a second positioning groove (12), a third positioning groove (13), a fourth positioning groove (14) and a fifth positioning groove (15) connected in sequence, and the second positioning groove (12) and the fourth positioning groove (14) are arranged in parallel. The optical fiber assembly (2) comprises a first tail fiber (21), a first fiber grating (22), a second tail fiber (23), a second fiber grating (24) and a third tail fiber (25) connected in sequence, and the first fiber grating (22) and the second fiber grating (24) are used to sense the strain of the heat transfer pipe of the heat exchanger. The first tail fiber (21) is arranged on the first positioning groove (11), the first fiber grating (22) is arranged on the second positioning groove (12), the second tail fiber (23) is arranged on the third positioning groove (13), the second fiber grating (24) is arranged on the fourth positioning groove (14), and the third tail fiber (25) is arranged on the fifth positioning groove (15).

2. The nuclear power plant heat exchanger heat transfer tube fiber grating strain sensor of claim 1, wherein, The second positioning groove (12) and the fourth positioning groove (14) are provided with a first glue injection hole (31) and a pair of first action holes (32), and a pair of first action holes (32) are arranged on the two sides of the first glue injection hole (31).

3. The nuclear power plant heat exchanger heat transfer tube fiber grating strain sensor of claim 2, wherein, The package shell (1) is provided with a first adhesive part (16) and a second adhesive part (17), the first adhesive part (16) and the second adhesive part (17) are provided with an adhesive part, and the first adhesive part (16) and the second adhesive part (17) are provided with a through hole (18).

4. The nuclear power plant heat exchanger heat transfer tube fiber grating strain sensor of claim 3, wherein, The number of the first adhesive part (16) and the second adhesive part (17) is two, two first adhesive parts (16) are arranged on the two sides of the second positioning groove (12), and two second adhesive parts (17) are arranged on the two sides of the fourth positioning groove (14).

5. The nuclear power plant heat exchanger heat transfer tube fiber grating strain sensor of claim 3, wherein, The package shell (1) is provided with a first glue injection groove (101) and a second glue injection groove (102), the first glue injection groove (101) is arranged along the circumferential side direction of the first adhesive part (16), and the second glue injection groove (102) is arranged along the circumferential side direction of the second adhesive part (17). The first glue injection groove (101) and the second glue injection groove (102) are provided with a plurality of second glue injection holes (33) and a plurality of second action holes (34).

6. The nuclear power plant heat exchanger heat transfer tube fiber grating strain sensor of claim 5, wherein, The package shell (1) is provided with a third glue injection groove (103), and the third glue injection groove (103) is located at the middle position between the first glue injection groove (101) and the second glue injection groove (102).

7. The nuclear power plant heat exchanger heat transfer tube fiber grating strain sensor of claim 6, wherein, The third glue injection groove (103) is provided with a third glue injection hole (35) and a pair of third action holes (36), and a pair of third action holes (36) are arranged on the two sides of the third glue injection hole (35).

8. The nuclear power plant heat exchanger heat transfer tube fiber grating strain sensor of claim 1, wherein, The package shell (1) is provided with a plurality of positioning holes (19), and a plurality of positioning holes (19) are arranged at the four corner positions of the package shell (1).

9. The nuclear power plant heat exchanger heat transfer tube fiber grating strain sensor of claim 1, wherein, The fifth positioning groove (15) is arranged obliquely relative to the first positioning groove (11), and the distance between the fifth positioning groove (15) and the first positioning groove (11) gradually decreases along the direction of the second positioning groove (12) towards the first positioning groove (11).

10. The nuclear power plant heat exchanger tube strain sensor of claim 1, wherein, The reflection center wavelength difference between the first fiber grating (22) and the second fiber grating (24) is greater than or equal to 5nm.

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