CN215414137U - Diaphragm type small-size fiber grating sensor for measuring high temperature and high pressure - Google Patents
Diaphragm type small-size fiber grating sensor for measuring high temperature and high pressure Download PDFInfo
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- CN215414137U CN215414137U CN202121458869.2U CN202121458869U CN215414137U CN 215414137 U CN215414137 U CN 215414137U CN 202121458869 U CN202121458869 U CN 202121458869U CN 215414137 U CN215414137 U CN 215414137U
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Abstract
The utility model discloses a diaphragm type small-size fiber grating sensor for measuring high temperature and high pressure, which relates to the field of fiber sensing and comprises a cylinder framework, a cover plate, an end cover, a temperature grating and a pressure grating. The cylinder framework, the cover plate and the end cover are sealed by laser welding, and a closed air cavity is formed inside the sensor. The pressure grid is fixed on the framework by adhesive, and the temperature sensitive grid connected in series with the pressure grid is in direct contact with the framework and is in a free state. According to the utility model, the temperature grid and the pressure grid are both in direct contact with the framework, so that the wavelength response time of temperature and pressure is fast; the temperature grid can accurately eliminate the temperature influence in the pressure grid in real time, and the pressure precision is improved; the temperature grating has the capability of accurately measuring the absolute temperature of the environment, and solves the problem that the common fiber grating pressure sensor cannot realize the simultaneous measurement of the temperature and the pressure in the environment with rapid temperature change; the sensor has the advantages of small size and wide range, can monitor the temperature and pressure of the high-temperature and high-pressure environment of the oil well for a long time, and realizes quasi-distributed pressure measurement.
Description
Technical Field
The utility model relates to the field of optical fiber sensing, in particular to a diaphragm type small-size optical fiber grating sensor for measuring high temperature and high pressure.
Background
Compared with the traditional electromagnetic pressure sensor, the fiber grating pressure sensor has the advantages of strong electromagnetic interference resistance, corrosion resistance, long transmission distance, easiness in reuse and the like, and has wide application prospect in the petrochemical field of long-term monitoring of the temperature and pressure profile of a large-depth oil well and the like due to the large-range and small-size fiber grating sensor for simultaneously measuring temperature and pressure.
SUMMERY OF THE UTILITY MODEL
The utility model aims to overcome the defects in the prior art, and provides a diaphragm type small-size fiber grating sensor for measuring high temperature and high pressure, which has the advantages of simple structure, small size and good stability.
The purpose of the utility model is achieved by the following technical scheme: the diaphragm type small-size fiber grating sensor for measuring high temperature and high pressure comprises a cylinder framework, a cover plate, an end cover, a temperature grating and a pressure grating, wherein an opening at one side of the cylinder framework is used for being matched with the installation of the cover plate to form a cylinder structure with one end closed and the other end open; the inner wall of the cylinder framework is provided with a rectangular platform which protrudes towards one side of the mounting cover plate, the inner wall of the cylinder framework is also provided with two bosses at intervals, and the bosses also protrude towards one side of the mounting cover plate; two ends of the pressure grid are respectively fixed on the two bosses, and a layer of elastic membrane is laid on the outer wall of the cylinder framework; one side of the temperature grid is in contact fit with the surface of the rectangular platform, the other side of the temperature grid is in a free extension state and is connected with one end of the pressure grid in series through optical fibers, and the other end of the pressure grid penetrates out of the end cover through the optical fibers to be connected with external equipment, so that measured data output is achieved.
As a further technical scheme, the cylinder framework, the cover plate and the end cover are sealed by laser welding and are all made of titanium alloy materials.
As a further technical scheme, the thickness of the cover plate and the thickness of the end cover are both far larger than the wall thickness of the cylindrical framework.
As a further technical scheme, the wavelength interval between the temperature grid and the pressure grid is more than or equal to 2 nm.
As a further technical scheme, the pressure grid is fixed on the two bosses by using an adhesive, and the adhesive is epoxy glue or glass solder; and applying pretension force in the bonding and packaging process of the pressure grid to enable the generated wavelength drift to be 0.5 nm-1 nm.
As a further technical scheme, grooves are formed in the positions, close to the two bosses, on the outer wall of the cylindrical framework.
The utility model has the beneficial effects that: the pressure grid is directly bonded with the boss inside the cylinder framework, a mechanical force transmission structure does not exist, and the pressure response time is short; the wavelength and the pressure linearity of the pressure grating are good, the stability is high, and high pressure measurement precision is ensured; the tail end of the temperature grid is in a free state, so that the real-time measurement of the ambient temperature can be realized, the influence of temperature change in the pressure grid can be eliminated, and the problem that the common fiber grating pressure sensor cannot realize the pressure measurement in the rapid temperature changing environment is solved; the sensor adopts a wavelength demodulation method, can realize multiplexing of a plurality of sensors by combining with a light path design, and has quasi-distributed temperature and pressure measurement capability; the problem of cross sensitivity of the temperature and the pressure of the fiber bragg grating is effectively solved; the sensor has small-size characteristics, and the size is about 12mm 57mm, makes things convenient for installation in the pit and with other monitoring system's integration.
Drawings
Fig. 1 is a structural sectional view of the present invention.
Fig. 2 is a structural plan view of the cylindrical skeleton.
FIG. 3 is a schematic diagram of simulation results under a pressure of 60 MPa.
Description of reference numerals: the device comprises a cylinder framework 1, a cover plate 2, an end cover 3, a temperature grid 4, a pressure grid 5, a rectangular platform 6, a boss 7 and a groove 8.
Detailed Description
The utility model will be described in detail below with reference to the following drawings:
example (b): as shown in fig. 1 and 2, the diaphragm-type small-size fiber grating sensor for measuring high temperature and high pressure comprises a cylinder framework 1, a cover plate 2, an end cover 3, a temperature grating 4 and a pressure grating 5, wherein the cylinder framework 1, the cover plate 2 and the end cover 3 are sealed in a laser welding manner, and a sealed air cavity is formed inside the sensor. The pressure grid 5 is fixed on two cylindrical bosses 7 inside the cylinder framework 1 by adhesive, as shown in figure 2, thin elastic membranes as pressure chambers are arranged outside the two bosses 2, and the thickness of the membranes determines the pressure sensitivity of the pressure grid, and further determines the pressure measurement range of the pressure grid 5. The direct bonding of the pressure grid 5 eliminates the intermediate transmission of force, and ensures high-precision measurement of pressure while realizing quick response of the pressure of the sensor. A raised rectangular platform 6 is arranged in the cylindrical framework 1, as shown in the attached drawing 2, the height of the platform is consistent with that of the temperature grid 4, the platform is kept in a free state while being attached to the temperature grid 4, the temperature grid 4 is only sensitive to the outside temperature, and meanwhile, the rapid response of the temperature grid 4 to the outside temperature change is ensured. The bonding pressure grid 5 can be made of high-temperature-resistant epoxy glue or glass solder. The outer wall of the cylinder framework 1 is provided with a groove 8 at the position close to the two bosses 7.
The temperature grating 4 and the pressure grating 5 are series fiber grating strings, the two fiber grating strings have the same parameters except different wavelengths, the wavelength interval between the two fiber grating strings is not less than 2nm, and the pressure grating 5 is stuck on the two bosses 7 of the cylinder framework 1 in a mode of fixing two end points, so that the phenomenon of burr or widening of the reflection peak of the fiber grating can be prevented. The temperature grid 4 is attached to the inner surface of the cylindrical framework 1 and is in a free state, so that good wavelength-temperature linearity can be kept, and the temperature measurement accuracy is ensured. The pressure grid 5 applies a certain pre-tension force in the bonding and packaging process to keep good wavelength-pressure/temperature linearity, wavelength drift generated by the pre-tension force is preferably about 0.5nm and not more than 1nm, and the fracture of the grating caused by too large total drift of the pressure grid in a wide-range pressure and temperature environment is prevented. In the process of pressure measurement, the wavelength variation of the temperature grid 4 and the pressure grid 5 is differed, so that the influence of temperature variation on pressure measurement can be eliminated, and temperature insensitive measurement is realized.
The working principle of the utility model is as follows: when the sensor is placed in an oil well, the pressure in the oil well acts on the outer wall of the cylindrical framework 1, the thin pressure diaphragm on the outer wall of the cylindrical framework 1 is deformed, and as shown in fig. 3, the deformation of the diaphragm causes the grid pitch of the pressure grid 5 fixed on the back surface of the diaphragm to change, so that the wavelength drift linearly related to the pressure is generated, namely, the pressure coefficient of the corresponding pressure grid 5 is generated. The simulation result shows that under the pressure of 60MPa, the strain value caused by the deformation of the diaphragm is converted into the wavelength drift of the pressure grid 5 of 2.776nm, the pressure coefficient reaches 46pm/MPa, and the pressure measuring sensitivity is higher. The temperature grid 4 is attached to the rectangular platform 6 in the cylindrical framework 1, and the tail part of the temperature grid is in a free state, so that the temperature grid is not influenced by pressure. The temperature in the oil well can also cause the wavelength of the temperature grid 4 and the pressure grid 5 to drift, the temperature is respectively transmitted to the temperature grid 4 and the pressure grid 5 through the rectangular platform 6 and the cylindrical boss 7, and the temperature value is directly calculated by the temperature grid 4 according to the temperature coefficient, so that the temperature measurement function is realized; the pressure grid 5 calculates a pressure value according to the temperature value by combining the temperature coefficient and the pressure coefficient, so as to realize the measurement of the environmental pressure. The two synchronous responses to the environmental temperature change effectively solve the problem of cross sensitivity of the fiber bragg grating temperature and pressure, and the sensor can work in the environment with the temperature change. Under the environment of 150 ℃ and 60MPa, the total wavelength drift amount of the pressure grating is about 5nm, and the performance of the fiber grating is stable for a long time in the wavelength drift range.
It should be understood that equivalent alterations and modifications of the technical solution and the inventive concept of the present invention by those skilled in the art should fall within the scope of the appended claims.
Claims (5)
1. A diaphragm type small-size fiber grating sensor for measuring high temperature and high pressure is characterized in that: the sensor comprises a cylinder framework (1), a cover plate (2), an end cover (3), a temperature grid (4) and a pressure grid (5), wherein an opening at one side of the cylinder framework (1) is used for being matched with the cover plate (2) to form a cylindrical structure with one closed end and the other open end, the end cover (3) is arranged at the open end of the cylindrical structure in a sealing way, the cylinder framework (1), the cover plate (2) and the end cover (3) are matched in a sealing way to form a sensor shell, and an inner cavity of the sensor shell forms a closed air cavity; a rectangular platform (6) is arranged on the inner wall of the cylindrical framework (1), the rectangular platform (6) protrudes towards one side of the mounting cover plate (2), two bosses (7) are arranged on the inner wall of the cylindrical framework (1) at intervals, and the bosses (7) also protrude towards one side of the mounting cover plate (2); two ends of the pressure grid (5) are respectively fixed on the two bosses (7), and a layer of elastic membrane is laid on the outer wall of the cylinder framework (1); one side of the temperature grid (4) is in contact fit with the surface of the rectangular platform (6), the other side of the temperature grid (4) is in a free extension state and is connected with one end of the pressure grid (5) in series through optical fibers, and the other end of the pressure grid (5) penetrates out of the end cover (3) through the optical fibers to be connected with external equipment, so that measurement data output is realized.
2. The diaphragm type small-sized fiber grating sensor for measuring high temperature and high pressure according to claim 1, wherein: the cylinder framework (1), the cover plate (2) and the end cover (3) are sealed by laser welding and are all made of titanium alloy materials.
3. The diaphragm type small-sized fiber grating sensor for measuring high temperature and high pressure according to claim 1, wherein: the wavelength interval between the temperature grid (4) and the pressure grid (5) is more than or equal to 2 nm.
4. The diaphragm type small-sized fiber grating sensor for measuring high temperature and high pressure according to claim 1, wherein: the pressure grid (5) is fixed on the two bosses (7) by using an adhesive, and the adhesive is epoxy glue or glass solder; and applying pretension force in the bonding and packaging process of the pressure grid (5) to enable the wavelength drift generated by the pretension force to be 0.5 nm-1 nm.
5. The diaphragm type small-sized fiber grating sensor for measuring high temperature and high pressure according to claim 1, wherein: the outer wall of the cylinder framework (1) is provided with a groove (8) at a position close to the two bosses (7).
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121458869.2U CN215414137U (en) | 2021-06-29 | 2021-06-29 | Diaphragm type small-size fiber grating sensor for measuring high temperature and high pressure |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121458869.2U CN215414137U (en) | 2021-06-29 | 2021-06-29 | Diaphragm type small-size fiber grating sensor for measuring high temperature and high pressure |
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| CN215414137U true CN215414137U (en) | 2022-01-04 |
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| CN202121458869.2U Active CN215414137U (en) | 2021-06-29 | 2021-06-29 | Diaphragm type small-size fiber grating sensor for measuring high temperature and high pressure |
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| CN (1) | CN215414137U (en) |
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2021
- 2021-06-29 CN CN202121458869.2U patent/CN215414137U/en active Active
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