Distributed optical fiber liquid level measuring device with adjustable precision

Abstract

The utility model provides a distributed optical fiber liquid level measuring device with adjustable precision. The measuring device comprises a flange cover, a temperature sensing optical cable, a metal spiral tube and a balancing weight, the flange cover is a metal cover plate provided with an optical cable installation through hole, the metal spiral tube is a spiral protection tube with two open ends, the metal spiral tube is fixedly installed at the bottom of the flange cover, the open end of the upper end of the metal spiral tube corresponds to the optical cable installation through hole of the flange cover, and the balancing weight is arranged in the metal spiral tube. The temperature sensing optical cable is inserted into the metal spiral pipe from the optical cable installation through hole formed in the flange cover and penetrates through the metal spiral pipe, the bottom end of the temperature sensing optical cable is fixed to a lower end pipe opening of the metal spiral pipe, the lower end pipe opening of the metal spiral pipe is sealed through the end socket, and the balancing weight is fixed to the bottom end of the metal spiral pipe. According to the measuring precision, the weight of the balancing weight can be changed according to actual use requirements, so that the screw pitch of the metal spiral pipe is increased or reduced, and the liquid level measuring precision of the device is adjusted.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of optical fiber liquid level measurement, concretely relates to a distributed optical fiber liquid level measuring device with adjustable precision. BACKGROUND

[0002] The optical fiber liquid level measuring device is a device for detecting liquid height by using optical fiber as a sensing medium, has various advantages, such as electrical isolation, anti-electromagnetic interference, corrosion resistance and the like, and is suitable for safe work in flammable and explosive special environments. The optical fiber liquid level measuring device has wide application fields, including but not limited to aircraft fuel measurement, ship liquid level measurement, chemical liquid tank measurement and the like, and can be applied to occasions with high anti-explosion requirements and corrosive environments.

[0003] Most of the conventional liquid level sensors are float ball type and capacitive type liquid level sensors. The float ball type liquid level sensor can be affected by liquid viscosity and float blockage, and the capacitive type liquid level sensor can need to be calibrated, can only be used in certain liquids, can not be sensitive to liquids with low dielectric constant, usually has poor anti-electromagnetic interference capability, cannot work safely and reliably for a long time in harsh environments such as high temperature and strong electromagnetic interference, has difficulty in long-distance transmission of measurement signals, and needs a large number of data transmission signal lines in the liquid level monitoring system due to the inability to be connected in series between sensors.

[0004] Based on the demand for distributed liquid level measurement, among the types of liquid level sensors developed at present, the photoelectric sensor still has the problem of low precision of electric signal transmission and extraction at low voltage, and the optical fiber DTS is widely studied due to many advantages such as immunity to electromagnetic interference, high measurement precision, corrosion resistance and the like. However, the optical fiber DTS liquid level measuring device also has some disadvantages, such as a relatively complex system, influence of stress and vibration in the environment on signal transmission, and certain limitation of signal transmission distance, which can cause signal attenuation during long-distance transmission, and strict technical requirements for installation and maintenance. The optical fiber DTS liquid level measuring device has the advantages of simple and reliable packaging structure, small size, arrangement of optical fibers in a spiral tube, effective alleviation of stress influence caused by vibration, adjustable liquid level measurement precision and the like, and is particularly suitable for work in harsh environments such as high temperature and radiation.

[0005] The basic sensing principle of the optical fiber DTS liquid level measuring device includes: (1) optical time domain reflectometry (OTDR) principle: the DTS system utilizes the OTDR technology to determine the specific position of the scattering signal in the optical fiber; when the laser pulse is transmitted in the optical fiber and scattering occurs, the position of the scattering signal in the optical fiber can be determined by measuring the time of return of the scattered light; (2) Raman scattering effect: the DTS system measures the temperature according to the Raman scattering effect occurring in the optical fiber; the Raman scattering produces two different frequency lights, Stokes light and Anti-Stokes light; the intensity of the Anti-Stokes light is proportional to the temperature, while the intensity of the Stokes light is irrelevant to the temperature; in the Raman scattering, the intensity of the Anti-Stokes light increases with the increase of the temperature; the temperature of the scattering area can be determined by measuring the intensity ratio of the Anti-Stokes light to the Stokes light; if the temperature under the liquid surface in the container is much higher than the temperature above the liquid surface, the current liquid level height can be obtained by calculating the DTS temperature measurement value. SUMMARY

[0006] In order to overcome the defects and deficiencies in the above technical solutions, the utility model provides a precision adjustable distributed optical fiber liquid level measuring device, this measuring device has precision adjustable, high sensitivity, single channel measurement, response fast, simple manufacturing process and other advantages.

[0007] In order to achieve the above technical purpose, the utility model provides a precision adjustable distributed optical fiber liquid level measuring device, the measuring device includes flange cover, temperature sensing optical cable, metal spiral pipe and counter weight, the flange cover is the metal cover plate with optical cable installation through -hole, the metal spiral pipe is the spiral type protection pipe with both ends open, metal spiral pipe fixed mounting at the bottom of flange cover, and the open end of its upper end corresponds with the optical cable installation through -hole of flange cover, temperature sensing optical cable is inserted into metal spiral pipe from the flange cover with optical cable installation through -hole, and passes through metal spiral pipe, and its bottom end is fixed in the lower end pipe orifice of metal spiral pipe, and the lower end pipe orifice of metal spiral pipe is sealed through the end socket, the counter weight is fixed in the bottom end of metal spiral pipe.

[0008] The utility model more preferably technical scheme: temperature sensing optical cable is DTS temperature sensing optical cable, temperature sensing optical cable structure includes optical fiber core, protection layer, buffer layer, reinforcing element and outer sheath, the temperature measurement range of DTS temperature sensing optical cable is -40~ 150 DEG C.

[0009] The utility model more preferably technical scheme: temperature sensing optical cable is inserted and uses high temperature resistant epoxy glue with metal spiral pipe fixed in the pipe orifice position of metal spiral pipe after.

[0010] The utility model more preferably technical scheme: the counter weight is the metal weight with fixed hook, is fixed in the bottom end of metal spiral pipe with argon arc welding.

[0011] The preferred technical solution of this utility model is as follows: the diameter of the metal spiral tube is 300-500mm, the length of one turn of the spiral tube is 1000mm or 2000mm, and the pitch of the metal spiral tube is [not specified].

[0012] The principle of this fiber optic liquid level measuring device is that the temperature of the liquid inside the container is higher than that of the gas. By measuring the temperature values ​​at different heights inside the container, the liquid level value inside the container is indirectly measured. At this time, the pitch of the metal spiral tube of the fiber optic liquid level measuring device is the measurement accuracy.

[0013] The calculation of the liquid level measurement value of the fiber optic liquid level measuring device of this utility model is as follows: Let the liquid temperature in the container be T0, the gas temperature be T1, the current measuring point temperature of the temperature-sensing optical cable be T, the measuring point length be L, the spatial resolution be ΔL, the pitch of the metal spiral tube be h, the spiral diameter be d, and the spiral rise angle be β; if T = T0, then... If T1 < T < T0, then .

[0014] This utility model has the following effects:

[0015] (1) This utility model is provided with a metal spiral tube and a counterweight. The temperature sensing optical cable is inserted into the metal spiral tube from the flange cover inlet. Since the spatial resolution of the DTS measurement system is 1000mm, the measurement accuracy of this utility model can be adjusted according to actual usage requirements by changing the weight of the counterweight, thereby increasing or decreasing the pitch of the metal spiral tube and adjusting the liquid level measurement accuracy of the device.

[0016] (2) The temperature sensing element of the fiber optic liquid level measuring device of this utility model is a DTS temperature sensing optical cable. The temperature measurement range of the DTS system is -40 to 150℃, which can be applied to most liquid level measurement environments. The accuracy of temperature measurement can reach ±1℃ or higher, and the temperature resolution can be as low as 0.1℃ or 0.5℃. The spatial resolution of the DTS system can reach 1m or lower, which enables the system to accurately locate the position of temperature change.

[0017] (3) The fixing structure of this utility model is a flange cover, which adopts the standard flange size and is connected and fixed to the container to be measured to ensure the sealing of the container to be measured. Attached Figure Description

[0018] Fig. 1 This is a schematic diagram of the structure of this utility model;

[0019] Fig. 2 This is a structural diagram of the metal spiral tube in this utility model.

[0020] In the diagram: 1—Flange cover; 2—Temperature-sensing optical cable; 200—Temperature-sensing optical cable connector; 3—Metal spiral tube; 4—Counterweight; 5—End cap. DETAILED DESCRIPTION

[0021] The utility model will be further described below in combination with the drawings and embodiments. The drawings of the embodiments are Figs. 1-2 simplified and are only used for the purpose of clearly and concisely illustrating the embodiments of the utility model. The technical solutions shown in the drawings are specific solutions of the embodiments of the utility model, and are not intended to limit the scope of the utility model. Based on the embodiments of the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the utility model.

[0022] In the description of the utility model, it should be understood that the terms "upper", "lower", "inner", "outer", "left", "right" and the like indicate the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly used when the utility model product is placed, or the orientation or positional relationship commonly understood by those skilled in the art, and are only used for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the utility model.

[0023] In order to make the technical solutions and advantages of the utility model more easily understood, the following will be combined with specific embodiments and refer to the accompanying Fig. 1 , Fig. 2 The utility model will be further described below in combination with the drawings and embodiments. The drawings of the embodiments are

[0024] The embodiment provides a precision-adjustable distributed optical fiber liquid level measuring device, as shown in Figures Fig. 1 and Fig. 2 , the measuring device comprises a flange cover 1, a temperature sensing optical cable 2, a metal spiral pipe 3 and a counterweight 4, the flange cover 1 is a metal cover plate provided with an optical cable mounting through hole, the metal spiral pipe 3 is a spiral protective pipe with open ends, the metal spiral pipe 3 is fixedly installed at the bottom of the flange cover 1, the open end of the upper end thereof corresponds to the optical cable mounting through hole of the flange cover 1, the temperature sensing optical cable 2 is inserted into the metal spiral pipe 3 from the flange cover 1 provided with the optical cable mounting through hole and passes through the metal spiral pipe 3, the bottom end thereof is fixed at the lower end port of the metal spiral pipe 3, and the lower end port of the metal spiral pipe 3 is sealed by a head 5, and the counterweight 4 is fixed at the bottom end of the metal spiral pipe 3.

[0025] In the embodiment, the temperature sensing optical cable 2 is a DTS temperature sensing optical cable, and the temperature sensing optical cable structure comprises a fiber core, a protective layer, a buffer layer, a reinforcing element and an outer sheath; the protective layer is resistant to mechanical damage, environmental factors and chemical corrosion; the buffer layer is usually made of soft material such as butyl acrylate (PBT) or similar material to protect the optical fiber from tension and pressure; the reinforcing element is made of stainless steel metal hose, Kevlar fiber reinforcement and the like to improve the mechanical strength of the optical cable; and the outer sheath is usually made of corrosion-resistant and aging-resistant material such as polyvinyl chloride (PVC) or polyurethane (PU). The temperature measurement range of the DTS temperature sensing optical cable is -40-150 DEG C, which can be applied to most liquid level measurement environments; the temperature measurement accuracy can reach ± 1 DEG C or higher, and the temperature resolution can be as low as 0.1 DEG C or 0.5 DEG C; and the spatial resolution of the DTS system can reach 1 m or lower, which enables the system to accurately locate the position of temperature change.

[0026] In the embodiment, the flange cover 1 is provided with a metal cover plate with a cable installation through hole, which cooperates with the penetration of the temperature sensing optical cable 2; the metal spiral pipe 3 is a two-section open protective pipe, the lower end is sealed after penetrating the temperature sensing optical fiber 2 through the end cover 5, is fixed in the through hole position of the flange cover 1 by means of argon arc welding, and the temperature sensing optical cable 2 is fixed with the metal spiral pipe 3 at the pipe opening position of the metal spiral pipe 3 by using high-temperature resistant epoxy glue. The counterweight 4 is a metal weight provided with a fixed hook, which is fixed at the bottom end of the metal spiral pipe by means of argon arc welding. The spiral diameter of the metal spiral pipe 3 is 300-500 mm, and the length of one spiral of the spiral pipe is 1000 mm or 2000 mm, and the liquid level measurement accuracy is changed by adjusting the length of one spiral of the spiral pipe.

[0027] As an embodiment of the utility model, the installation sequence of the device is as follows: firstly, the upper end of the metal spiral pipe 3 is penetrated into the installation hole of the flange cover 1, the metal spiral pipe 3 and the flange cover 1 are reliably fixed by means of argon arc welding, according to the measurement accuracy requirement, the counterweight 4 with appropriate weight is selected, the bottom end of the metal spiral pipe is penetrated into the hook of the counterweight 4, the metal spiral pipe 3 and the counterweight 4 are reliably fixed by means of argon arc welding, then the temperature sensing optical cable 2 is penetrated into the metal spiral pipe 3, the temperature sensing optical cable 2 and the metal spiral pipe 3 are fixed by using high-temperature resistant epoxy glue, the bottom end of the metal spiral pipe is sealed by means of laser welding, the metal spiral pipe end cover 5 is formed, and finally the temperature sensing optical cable connector 202 and the communication optical cable are connected to the demodulation equipment by means of optical fiber fusion.

[0028] As an embodiment of the utility model, the flange cover 1, metal spiral pipe 3, counterweight 4 all adopt 316L stainless steel customization, have good corrosion resistance effect, the flange cover 1 size nominal outer diameter 105mm, thickness 5mm, temperature sensing optical cable outer diameter 2.9mm, metal spiral pipe 3 outer diameter 10mm, inner diameter 4mm, counterweight 4 outer diameter 50mm, height 200mm, weight 3kg, slowly put the fixed counterweight, metal spiral pipe and temperature sensing optical cable into the container to be measured, and seal and fix the flange cover with the container.

[0029] The above is only an embodiment of the utility model, but the utility model is not limited to the above embodiment, as long as any same or similar means achieves the technical effect of the utility model, it should belong to the protection scope of the utility model.

Claims

1. A precision-adjustable distributed optical fiber liquid level measuring device, characterized in that: The measuring device comprises a flange cover (1), a temperature sensing optical cable (2), a metal spiral pipe (3) and a counterweight (4), the flange cover (1) is a metal cover plate provided with an optical cable mounting through hole, the metal spiral pipe (3) is a spiral protective pipe with open ends, the metal spiral pipe (3) is fixedly installed at the bottom of the flange cover (1), the open end of the upper end thereof corresponds to the optical cable mounting through hole of the flange cover (1), the temperature sensing optical cable (2) is inserted into the metal spiral pipe (3) from the flange cover (1) provided with the optical cable mounting through hole and passes through the metal spiral pipe (3), the bottom end thereof is fixed at the lower end pipe opening of the metal spiral pipe (3), and the lower end pipe opening of the metal spiral pipe (3) is sealed by a sealing head (5), and the counterweight (4) is fixed at the bottom end of the metal spiral pipe (3).

2. The precision-adjustable distributed optical fiber liquid level measuring device according to claim 1, characterized in that: The temperature sensing optical cable (2) is a DTS temperature sensing optical cable, the structure of the temperature sensing optical cable comprises a fiber core, a protective layer, a buffer layer, a reinforcing element and an outer sheath, and the temperature measuring range of the DTS temperature sensing optical cable is -40-150 DEG C.

3. The precision-adjustable distributed optical fiber liquid level measuring device according to claim 1 or 2, characterized in that: After the temperature sensing optical cable (2) is inserted, the temperature sensing optical cable is fixed with the metal spiral pipe by using high-temperature resistant epoxy glue at the pipe opening position of the metal spiral pipe (3).

4. The precision-adjustable distributed optical fiber liquid level measuring device according to claim 1 or 2, characterized in that: The counterweight (4) is a metal weight provided with a fixed hook and is fixed at the bottom end of the metal spiral pipe by argon arc welding.

5. The precision-adjustable distributed optical fiber liquid level measuring device according to claim 1 or 2, characterized in that: The spiral diameter of the metal spiral pipe (3) is 300-500 mm, the length of one spiral of the spiral pipe is 1000 mm or 2000 mm, and the pitch of the metal spiral pipe.

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