CN203758706U - Negative pressure wave theory based polyvinylidene fluoride (PVDF) leakage detecting sensor for petroleum pipeline - Google Patents
Negative pressure wave theory based polyvinylidene fluoride (PVDF) leakage detecting sensor for petroleum pipeline Download PDFInfo
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- CN203758706U CN203758706U CN201420118594.1U CN201420118594U CN203758706U CN 203758706 U CN203758706 U CN 203758706U CN 201420118594 U CN201420118594 U CN 201420118594U CN 203758706 U CN203758706 U CN 203758706U
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- polyvinylidene fluoride
- piezoelectric film
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- negative pressure
- pressure wave
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- 239000003208 petroleum Substances 0.000 title abstract description 6
- 229920000139 polyethylene terephthalate Polymers 0.000 claims abstract description 29
- 239000005020 polyethylene terephthalate Substances 0.000 claims abstract description 29
- -1 polyethylene terephthalate Polymers 0.000 claims abstract description 27
- 238000001514 detection method Methods 0.000 claims abstract description 17
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Abstract
The utility model discloses a negative pressure wave theory based PVDF leakage detecting sensor for a petroleum pipeline. The leakage detecting sensor comprises a pedestal, a polyethylene terephthalate (PET) film, a PVDF piezoelectric film, a positive electrode and a negative electrode, wherein the PET film is mounted at an opening end of the pedestal, the PVDF piezoelectric film is fixed at the center of the lower surface of the PET film, and positioned inside the pedestal, the positive electrode is arranged at the upper surface of the PVDF piezoelectric film, the negative electrode is arranged at the lower surface of the PVDF piezoelectric film, and the positive and negative electrodes are respectively connected with a lead I and a lead II, and are led out through of a small hole at the bottom end of the pedestal. The PVDF leakage detecting sensor can detect change of fluid parameters when little leakage is detected in the petroleum pipeline, the size of the sensor is decreased, and the technology is improved; the low-frequency scope of the sensor is widened, and the anti-interference capability in the lower frequency range is enhanced; and the flexibility and resolution of leakage detection are improved, and a leakage point can be positioned more accurately.
Description
Technical Field
The utility model relates to an defeated oil pipe leakage detection sensor of polyvinylidene fluoride based on negative pressure wave theory especially relates to a defeated oil pipe leakage detection sensor based on negative pressure wave theory of novel piezoelectric material and novel structure.
Background
The petroleum is transported through the petroleum pipeline, and the petroleum pipeline has the characteristics of large transportation capacity, safety, reliability, no pollution, small occupied area and energy consumption and low cost. The long-distance oil delivery pipe becomes an important component of the energy aorta in China and has a quite high strategic position. The leakage of the oil delivery pipe directly threatens the life of people and the property safety of the state, and can cause serious economic loss and natural environment pollution at the same time. Therefore, it is very important to find the leakage of the oil delivery pipe in time and accurately locate the leakage point. Aiming at the characteristics of crude oil and oil pipelines in China, the negative pressure wave theory is widely applied to practical detection. The detection method based on the negative pressure wave theory has very high requirements on the sensor. In order to overcome the defects of detection sensitivity and resolution of the traditional piezoelectric transmitter used at present, the sensor adopting a novel high-molecular piezoelectric material polyvinylidene fluoride and an elastic material polyethylene terephthalate and adopting a novel structural design is provided, the size is reduced, the process is improved, and the accuracy of leakage point positioning is improved.
Disclosure of Invention
The utility model provides an defeated oil pipe leakage detection sensor of polyvinylidene fluoride based on negative pressure wave theory adopts polyvinylidene fluoride piezoelectric film to be the defeated oil pipe leakage detection sensor based on negative pressure wave theory of sensing element and novel structure to improve leak detection's sensitivity and resolution ratio, improve the accuracy of leakage point location.
The utility model discloses polyvinylidene fluoride defeated oil pipe leakage detection sensor based on negative pressure wave theory includes base 1, polyethylene terephthalate film 2, polyvinylidene fluoride piezoelectric film 3, positive electrode 8, negative electrode 9 as polyvinylidene fluoride defeated oil pipe leakage detection sensor main part, and polyethylene terephthalate film 2 is installed at the open end of base 1, and polyethylene terephthalate film 2 is as the transducer element, and elastic modulus is high, has very high intensity and elasticity limit; the polyvinylidene fluoride piezoelectric film 3 is fixed in the center of the lower surface of the polyethylene terephthalate film 2 and is positioned inside the base 1, the positive electrode 8 is arranged on the upper surface of the polyvinylidene fluoride piezoelectric film 3, the negative electrode 9 is arranged on the lower surface of the polyvinylidene fluoride piezoelectric film 3, and the positive electrode 8 and the negative electrode 9 are respectively connected with the lead I5 and the lead II 6 and are led out from the small hole 7 at the bottom end of the base 1.
In the utility model, the base 1 is a hollow cylinder, and the upper bottom surface is open; one side of the base 1 is provided with a small threaded hole 4, and the small threaded hole 4 is used for fixing the sensor on the inner wall of the oil pipe.
The utility model discloses in polyvinylidene fluoride piezoelectric film 3 is circular film, is fixed in the positive center department of 2 lower surfaces of polyethylene terephthalate film through the interior propionic acid adhesive of cyano-group.
The utility model discloses in the biggest strain center department in the 2 strain areas of polyethylene terephthalate film, sensing element polyvinylidene fluoride piezoelectric film 3 can make full use of the strain state of polyethylene terephthalate film 2, therefore fix circular structure polyvinylidene fluoride piezoelectric film 3 in the lower surface center department of polyethylene terephthalate film 2, hide in the sensor inside; the hollow structure design of the base 1 enables the polyethylene terephthalate film 2 and the polyvinylidene fluoride piezoelectric film 3 to be in a stretching working state; the polyethylene terephthalate film 2 and the polyvinylidene fluoride piezoelectric film 3 form an elastic diaphragm structure; when the oil conveying pipe is slightly leaked, the elastic diaphragm structure, namely the polyethylene terephthalate film 2 and the polyvinylidene fluoride piezoelectric film 3 are slightly deformed, and certain charges are generated on the upper surface and the lower surface of the polyvinylidene fluoride piezoelectric film 3.
In the scheme, the polyvinylidene fluoride piezoelectric film 3 and the polyethylene terephthalate film 2 are fixed by the cyano-group propionic acid adhesive with temperature resistance, water resistance, oil resistance, corrosion resistance, good insulativity and high adhesive strength, so that the null shift generated in the use process of the sensor can be effectively reduced, the hysteresis effect is reduced, and the service life is prolonged.
When pressure difference exists between the inside and the outside of the closed oil conveying pipe, oil body can leak through the positions similar to the holes and the seams. When a leak occurs somewhere in the pipeline, a negative pressure wave is generated which propagates upstream and downstream, and the consequent pressure change can be detected by installing sensors at the head end 11 and the tail end 13 of the pipeline 10. Pressure, flow rate, density and temperature are fluid parameters, oil flowing in an oil pipeline is regarded as unitary fluid, and a fluid dynamic model is established:
（1）
（2）
（3）
wherein,、、、、、、、、、、respectively, the flow velocity of the fluid, the density of the fluid, the pressure in the pipe, the diameter of the pipe 10, the heat transfer coefficient of the pipe 10, the gravity acceleration, the specific heat capacity of the oil product, the temperature of the land, the position variable of the pipe 10 and the time, wherein the units are respectively、、、、、、、、、、；、The hydraulic friction coefficient of the pipeline 10 and the included angle between the pipeline 10 and the horizontal plane are respectively.
The elastic diaphragm structure-the polyethylene terephthalate film 2 and the polyvinylidene fluoride piezoelectric film 3 have no vertical external load, the strain response of the two-dimensional stress is the algebraic sum of the transverse strain and the longitudinal strain, and the output charge of the polyvinylidene fluoride piezoelectric film 3 is as follows:
（4）
wherein,、the elastic modulus of the polyvinylidene fluoride piezoelectric film 3 and the area of the polyvinylidene fluoride piezoelectric film 3 are respectively expressed by、；Andrespectively strain and piezoelectric constant.
Based on the negative pressure wave theory, the leak 12 of the pipeline 10 is positioned, and the method comprises the following steps:
（5）
wherein,、、、、the length of the pipeline 10, the distance from the leak 12 to the head end 11, the wave velocity of the negative pressure wave, the time difference of the negative pressure wave reaching the head end 11 and the tail end 13, and the fluid flow rate are respectively expressed in units of、、、、。
The wave speed of the negative pressure wave can be determined by the following formula:
（6）
wherein,、、、、respectively the wave velocity, the temperature, the elastic modulus, the diameter of the pipeline 10 and the wall thickness of the pipeline 10 of the negative pressure wave, and respectively、、、、；Is a correction factor for the relevant constraint of the pipeline 10;andrespectively, the fluid bulk modulus and the fluid density as a function of temperature.
The utility model discloses following beneficial effect has:
1. the utility model provides a this kind of defeated oil pipe leakage piezoelectric transducer based on negative pressure wave theory adopts two elastic diaphragm frameworks about hollow structure's the base cooperation, carries out the sensitization to piezoelectric transducer, the effectual sensitivity that improves the sensor.
2. The utility model provides a this kind of defeated oil pipe based on negative pressure wave theory leaks piezoelectric transducer adopts the polyethylene terephthalate film as transducing element, utilizes its elastic modulus height, has the characteristics of very high intensity and elasticity limit, even very small leakage takes place for the pipeline, produced pressure differential also can be detected.
3. The utility model provides a this kind of defeated oil pipe leakage piezoelectric transducer based on negative pressure wave theory adopts polyvinylidene fluoride piezoelectric film as sensing element, utilizes its good piezoelectricity characteristic, especially the good characteristics of low frequency performance, has widened the low frequency range of sensor, has strengthened its interference killing feature at the low frequency channel.
Drawings
Fig. 1 is a schematic structural diagram of the present invention;
FIG. 2 is a schematic diagram of the adhesion of a polyvinylidene fluoride piezoelectric film and a polyethylene terephthalate film according to the present invention;
fig. 3 is a schematic view of the electrode lead-out structure of the present invention;
FIG. 4 is a schematic view of the leakage point positioning principle of the present invention;
in the figure: 1-a base; 2-polyethylene terephthalate film; 3-polyvinylidene fluoride piezoelectric film; 4-threaded small holes; 5-a wire I; 6-lead II; 7-small holes; 8-a positive electrode; 9-a negative electrode; 10-a pipeline; 11-head end; 12-leakage point; 13-terminal.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to the accompanying drawings.
The polyvinylidene fluoride oil pipeline leakage detection sensor based on the negative pressure wave theory comprises a base 1, a polyethylene terephthalate film 2, a polyvinylidene fluoride piezoelectric film 3, a positive electrode 8 and a negative electrode 9, wherein the base 1 is used as a main body of the polyvinylidene fluoride oil pipeline leakage detection sensor, the polyethylene terephthalate film 2 is arranged at the opening end of the base 1, and the polyethylene terephthalate film 2 is used as an energy conversion element and has high elastic modulus, high strength and high elastic limit; the polyvinylidene fluoride piezoelectric film 3 is fixed at the right center of the lower surface of the polyethylene terephthalate film 2 and is positioned in the base 1, the positive electrode 8 is arranged on the upper surface of the polyvinylidene fluoride piezoelectric film 3, the negative electrode 9 is arranged on the lower surface of the polyvinylidene fluoride piezoelectric film 3, and the positive electrode 8 and the negative electrode 9 are respectively connected with the lead I5 and the lead II 6 and are led out from the small hole 7 at the bottom end of the base 1; wherein the base 1 is a hollow cylinder, and the upper bottom surface is open; one side of the base 1 is provided with a small threaded hole 4, and the small threaded hole 4 is used for fixing the sensor on the inner wall of the oil pipe; the polyvinylidene fluoride piezoelectric film 3 is a circular film and is fixed at the center of the lower surface of the polyethylene terephthalate film 2 by cyano-group propionic acid adhesive (see fig. 1).
As shown in fig. 2, a circular polyvinylidene fluoride piezoelectric film 3 is fixed at the center of the surface of a polyethylene terephthalate film 2 to form an elastic membrane structure;
as shown in fig. 3, the positive electrode 8 is disposed on the upper surface of the polyvinylidene fluoride piezoelectric film 3, the negative electrode is disposed on the lower surface of the polyvinylidene fluoride piezoelectric film 3, and the lead wires 8 and 9 are connected to be led out to form an output signal line of the polyvinylidene fluoride piezoelectric film 3.
The utility model provides a this kind of defeated oil pipe leaks piezoelectric transmitter's based on negative pressure wave theory of operation as follows:
the head end 11 and tail end 13 of the pipeline 10 are fitted with sensors as shown in figure 4. The leakage point 12 generates tiny leakage to generate negative pressure waves which are transmitted to upstream and downstream, the elastic diaphragm structures 2 and 3 generate tiny deformation, the upper surface and the lower surface of the polyvinylidene fluoride piezoelectric film 3 generate certain charges, and signals are output through the leads 8 and 9. After the wave speed of the negative pressure wave, the flow speed of the oil body, the length of the pipeline 10 between the head end 11 and the tail end 13 and the time difference of the negative pressure wave reaching the head end 11 and the tail end 13 are determined, the distance between the leakage point 13 and the head end 11 can be accurately calculated, and therefore the positioning of the leakage point is completed.
The sensitivity of the piezoelectric transmitter can be adjusted within a certain range by adjusting the parameters of the elastic diaphragm structure, such as thickness, elastic modulus and the like.
Claims (3)
1. The utility model provides a polyvinylidene fluoride defeated oil pipe leakage detection sensor based on negative pressure wave theory which characterized in that: the high-voltage power supply comprises a base (1), a polyethylene terephthalate film (2), a polyvinylidene fluoride piezoelectric film (3), a positive electrode (8), a negative electrode (9), wherein the polyethylene terephthalate film (2) is installed at the opening end of the base (1), the polyvinylidene fluoride piezoelectric film (3) is fixed at the center of the lower surface of the polyethylene terephthalate film (2) and is positioned inside the base (1), the positive electrode (8) is arranged on the upper surface of the polyvinylidene fluoride piezoelectric film (3), the negative electrode (9) is arranged on the lower surface of the polyvinylidene fluoride piezoelectric film (3), the positive electrode (8) and the negative electrode (9) are respectively connected with a wire I (5) and a wire II (6) and are led out from a small hole (7) at the bottom end of the base (1).
2. The polyvinylidene fluoride oil pipeline leakage detection sensor based on the negative pressure wave theory as claimed in claim 1, wherein: the base (1) is a hollow cylinder, and the upper bottom surface of the base is open; one side of the base (1) is provided with a small threaded hole (4) for fixing the sensor on the inner wall of the oil pipe.
3. The polyvinylidene fluoride oil pipeline leakage detection sensor based on the negative pressure wave theory as claimed in claim 1, wherein: the polyvinylidene fluoride piezoelectric film (3) is a circular film and is fixed at the center of the lower surface of the polyethylene terephthalate film (2) through cyano-propionic acid adhesive.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420118594.1U CN203758706U (en) | 2014-03-17 | 2014-03-17 | Negative pressure wave theory based polyvinylidene fluoride (PVDF) leakage detecting sensor for petroleum pipeline |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420118594.1U CN203758706U (en) | 2014-03-17 | 2014-03-17 | Negative pressure wave theory based polyvinylidene fluoride (PVDF) leakage detecting sensor for petroleum pipeline |
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| CN203758706U true CN203758706U (en) | 2014-08-06 |
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| CN201420118594.1U Expired - Fee Related CN203758706U (en) | 2014-03-17 | 2014-03-17 | Negative pressure wave theory based polyvinylidene fluoride (PVDF) leakage detecting sensor for petroleum pipeline |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110088588A (en) * | 2016-10-17 | 2019-08-02 | 麻省理工学院 | Pipeline internal leakage detection system, device and method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110088588A (en) * | 2016-10-17 | 2019-08-02 | 麻省理工学院 | Pipeline internal leakage detection system, device and method |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C53 | Correction of patent of invention or patent application | ||
| CB03 | Change of inventor or designer information |
Inventor after: Wan Zhou Inventor after: Li Yiyang Inventor after: Liu Haohua Inventor after: You Xicun Inventor after: Chen Zhuen Inventor before: Wan Zhou |
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| COR | Change of bibliographic data |
Free format text: CORRECT: INVENTOR; FROM: WAN ZHOU TO: WAN ZHOU LI YIYANG LIU HAOHUA YOU XICUN CHEN ZHUEN |
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140806 Termination date: 20150317 |
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| EXPY | Termination of patent right or utility model |