JP2007139441A - Sensor and liquid level meter for measuring liquid level of ultra cold liquefied gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor and a liquid level meter for measuring the liquid level of ultra cold liquefied gas high in reliability and precision capable of using for an enlarged storage vessel. <P>SOLUTION: The liquid level measurement sensor 1 for measuring the liquid level of ultra cold liquefied gas is provided with MgB<SB>2</SB>and covering metal, and is a long sized single core wire of 50 cm or more, the resistance of which is 1 Ω/m to 5 Ω/m at the normal temperature, and the heat conductivity is 5 W/(m×K) to 15 W/(m×K). The resin 9 for fixing the sensor 1 for measuring the liquid level in the cylinder 8 is dipped in the liquefied gas in the reserver vessel heated by the current from the power source 3 to the heater part 7, the upper part higher than the liquid level of the sensor 1 is made normal temperature state, the sensor 1 is energized by making flow the current from the DC current source 2, the voltage generated at both the terminals of the sensor 1 is measured by the voltmeter 4, from the voltage data by the operational process device 5, the liquid level is calculated and the position of the liquid level is displayed on the monitor 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultra-low temperature liquefied gas liquid level measuring sensor which can be measured efficiently and can be used for a large-sized container having a depth, and an ultra-low temperature liquefied gas liquid level measuring liquid level meter using the same.

  Cryogenic liquid gases such as liquid hydrogen, liquid helium, and liquid neon are widely used in industry. Particularly recently, liquid hydrogen has attracted attention from the viewpoint of introducing clean energy that is environmentally friendly.

  When storing the cryogenic liquefied gas as described above, a liquid level sensor and a liquid level gauge capable of measuring the liquid level in the storage container are necessary from the viewpoint of grasping the liquid amount and safety management. Yes (for example, see Patent Documents 1 and 2 below).

JP 2000-275085 A JP-A-50-127659

  Recently, since the usage amount of cryogenic liquefied gas is increasing, it is desired to increase the size of the storage container so as to increase the transport amount and the storage amount. However, conventional liquid level sensors and liquid level gauges such as Patent Documents 1 and 2 are not highly reliable and accurate, and it is difficult to make them long. Therefore, it has been difficult to employ an enlarged storage container (particularly a deep storage container) for storing cryogenic liquefied gas such as liquid hydrogen, liquid helium, or liquid neon.

  Accordingly, an object of the present invention is to provide an ultra-low temperature liquefied gas liquid level measuring sensor and an ultra-low temperature liquefied gas liquid level measuring liquid level meter that are highly reliable and accurate and can be used for an enlarged storage container. is there.

Means and effects for solving the problems

The ultra-low temperature liquefied gas liquid level measuring sensor of the present invention includes a long superconductor containing MgB ₂ and a coated metal covering the surface of the superconductor. From another point of view, the ultra-low temperature liquefied gas liquid level measurement sensor of the present invention may include a coiled superconductor containing MgB ₂ and a coated metal covering the surface of the superconductor. .

  With the above configuration, it is possible to provide an ultra-low temperature liquefied gas liquid level measuring sensor that has high reliability and accuracy and can be used for an enlarged storage container. In addition, in the case of a coiled ultra-low temperature liquefied gas liquid level measurement sensor, the effective length can be increased, so that the difference in resistance between the superconducting state portion and the normal conducting state portion in the superconductor can be further increased. . As a result, it is possible to provide an ultra-low temperature liquefied gas liquid level measurement sensor that is further excellent in reactivity (accuracy).

  The sensor for measuring the liquid level of the ultra-low temperature liquefied gas of the present invention preferably has a resistance value at room temperature of 1 Ω / m to 5 Ω / m.

  With the above configuration, the resistance value at room temperature is 1 Ω / m to 5 Ω / m, so it can be easily heated by passing an electric current, and an ultra-low temperature liquefied gas liquid level measurement sensor is used for liquid level measurement. In this case, the portion not immersed in the liquid surface can be kept in a normal conducting state. Moreover, since the difference in resistance value between the superconducting state portion and the normal conducting state portion in the superconductor is large, the reactivity (accuracy) as the ultra-low temperature liquefied gas liquid level measurement sensor can be made practically sufficient. Furthermore, since the resistance value is not too large, it is possible to provide a sensor for measuring the liquid level of an ultra-low temperature liquefied gas in which the vaporization of the liquefied gas is suppressed within an allowable range.

  The ultra-low temperature liquefied gas liquid level measurement sensor of the present invention preferably has a thermal conductivity of 5 W / (m · K) to 15 W / (m · K). As a result, it is possible to provide a sensor for measuring a liquid level of an ultra-low temperature liquefied gas, which can have a heating / cooling performance sufficient for practical use and is excellent in reactivity (accuracy).

  The ultra-low temperature liquefied gas liquid level measurement sensor of the present invention preferably has a length of 50 cm or more. Thereby, since it is possible to make the sensor longer than before, there is no need to obtain a distance by connecting a plurality of sensors vertically even when the container is deep. Therefore, it is possible to provide a sensor for an ultra-low temperature liquefied gas level gauge that can be used for a container having a depth.

  The ultra-low temperature liquefied gas liquid level measuring sensor of the present invention is a wire having an overall cross-sectional diameter of 0.5 mm to 2.0 mm, and the superconductor layer may occupy 30% to 60% of the cross-sectional area. preferable. As a result, it is possible to provide a sensor for measuring the liquid level of an ultra-low temperature liquefied gas, which can achieve the required strength and heating / cooling performance and is further excellent in reactivity (accuracy).

  In the ultra-low temperature liquefied gas liquid level measuring sensor of the present invention, the coating metal is preferably a Ni-Cu alloy. As a result, it is possible to provide an ultra-low temperature liquefied gas level sensor having excellent reactivity (accuracy).

  In the ultra-low temperature liquefied gas liquid level measurement sensor of the present invention, the ratio of Ni and Cu in the coated metal is preferably 3: 7 to 4: 6. If it is the ratio of this range, the sensor for ultra-low-temperature liquefied gas liquid level measurement excellent in reactivity (accuracy) especially can be provided.

  The ultra-low temperature liquefied gas level sensor of the present invention is preferably formed so as to be U-shaped as a whole.

  With the above configuration, since the effective length of the ultra-low temperature liquefied gas liquid level measurement sensor can be increased, the difference in resistance value between the superconducting state portion and the normal conducting state portion in the superconductor can be further increased. As a result, it is possible to provide an ultra-low temperature liquefied gas liquid level measurement sensor that is further excellent in reactivity (accuracy). Moreover, since it becomes easy to take an electrode, the connection with an external electric circuit etc. becomes easy.

  The ultra-low temperature liquefied gas liquid level measurement level gauge of the present invention includes the above-mentioned ultra-low temperature liquefied gas liquid level measurement sensor, a heater for heating the ultra-low temperature liquefied gas liquid level measurement sensor, and the ultra-low temperature liquefied gas liquid level measurement. And a voltmeter for measuring a voltage in the ultra-low temperature liquefied gas liquid level measuring sensor.

  With the above configuration, it is possible to heat the ultra-low temperature liquefied gas liquid level measurement sensor, and when a part is immersed in the ultra-low temperature liquefied gas, a difference in resistance value is created depending on the temperature difference between the immersed part and the non-immersed part. be able to. Therefore, at this time, a change in resistance value of the ultra-low temperature liquefied gas liquid level measurement sensor can be detected by flowing an electric current through the ultra-low temperature liquefied gas liquid level measurement sensor and measuring the voltage with a voltmeter. The liquid level position can be reliably detected.

  Hereinafter, the liquid level gauge for measuring the liquid level of the ultra-low temperature liquefied gas according to the first embodiment of the present invention will be described. FIG. 1 is a schematic configuration diagram of a liquid level gauge for liquid level measurement of an ultra-low temperature liquefied gas according to the first embodiment of the present invention.

  As shown in FIG. 1, an ultra-low temperature liquefied gas liquid level measuring liquid level gauge 10 (hereinafter referred to as a liquid level gauge 10) includes an ultra-low temperature liquefied gas liquid level measuring sensor 1 (hereinafter referred to as sensor 1) and a direct current. A current power source 2, a heater power source 3, a voltmeter 4, an arithmetic processing unit 5, a monitor 6, a heater unit 7, a cylinder 8, and a fixing resin 9 are provided. In addition, in FIG. 1, the cylinder 8 has shown the state immersed in the ultra-low temperature liquefied gas in a storage container (not shown) to the middle.

The sensor 1 is a long single-core wire made of a metal-coated superconductor MgB _{2 having} a length of 50 cm or more, a resistance value at room temperature of 1 Ω / m to 5 Ω / m, and a thermal conductivity of 5 W. / (M · K) to 15 W / (m · K). The sensor 1 is a wire having an overall cross-sectional diameter of 0.5 mm to 2.0 mm, and the MgB ₂ layer occupies 30% to 60% of the cross-sectional area.

The sensor 1 described above can be manufactured by a so-called powder-in-tube (PIT) method. Also in this PIT method, a mixed powder of Mg and B is packed into a sheath material (metal tube) to be a coating layer and processed to produce MgB ₂ by heat treatment (in-situ method), and a compound powder of MgB ₂ However, either method may be used.

As the sheath material comprising the MgB ₂ coating layer (metal tube), Ni-Cu alloy, Cu, Fe, stainless steel, Nb and the like. In the case of adopting a Ni-Cu alloy, one having a ratio of Ni and Cu adjusted to 3: 7 to 4: 6 is used. Thereby, the sensor 1 having excellent reactivity (accuracy) can be obtained.

  The direct current power source 2 is electrically connected to one end and the other end of the sensor 1, and is used to pass a current through the sensor 1.

  The heater power supply 3 is electrically connected to both ends of the heater unit 7 such as a high electric resistance body, and can generate resistance heat by flowing current through the heater unit 7 to heat the upper part of the sensor 1.

  The voltmeter 4 includes a direct-current amplifier (not shown), is electrically connected to one end and the other end of the sensor 1, and measures the voltage of the sensor 1.

  The arithmetic processing unit 5 calculates the resistance value of the sensor 1 from the voltage value measured by the voltmeter 4. The calculation result is displayed on the monitor 6.

  The cylinder 8 houses and protects the sensor 1 inside. The sensor 1 is fixed to the cylinder 8 with a fixing resin 9. Examples of the fixing resin 9 include an epoxy resin.

  Although not shown, in the storage container, the wiring outlet connecting the sensor 1 and each device is provided with a wiring so that it can be used even when the internal pressure of the storage container is increased. It is a pressure-resistant type using a hermetic seal or an O-ring. In addition, the wiring is covered with an insulating material in order to prevent it from igniting and burning / explosion due to contact of hydrogen with the wiring. Examples of this insulating material include fiber reinforced plastic in the cryogenic temperature portion of the sensor 1 and vinyl chloride resin in the room temperature portion.

  Next, the operation of the liquid level gauge 10 will be described. First, the cylinder 8 in which the sensor 1 is fixed is immersed in the liquefied gas in the storage container, and a current is passed from the heater power supply 3 to the heater section 7 to heat the sensor. Leave it in a state. Next, a current is passed from the direct current power source 2 to the sensor 1, the voltage generated at both ends of the sensor 1 is measured by the voltmeter 4, and the voltage value data is stored in the arithmetic processing unit 5. Then, according to an algorithm determined based on the measurement data (for example, according to a relational expression between the voltage value and the liquid level position previously derived from the experimental data), the arithmetic processing unit 5 calculates the liquid level position from the voltage value data. And the liquid level position is displayed on the monitor 6.

  According to the level gauge 10 having the above-described configuration, the reliability and accuracy are high, and it can be used for an enlarged storage container. Moreover, since the resistance value at the normal temperature of the sensor 1 is 1 Ω / m to 5 Ω / m, it can be easily heated by passing an electric current, and when the sensor 1 is used for liquid level measurement, A portion not immersed in the surface can be kept in a normal conducting state. Further, since the difference in resistance value between the superconducting state portion and the normal conducting state portion in the superconductor is large, the liquid level gauge 10 having the reactivity (accuracy) as the sensor 1 sufficient for practical use is obtained. Therefore, since a change in the resistance value of the sensor 1 can be detected by passing a current from the DC current power source 2 to the sensor 1 and measuring the voltage with the voltmeter 4, the liquid level of the ultra-low temperature liquefied gas can be calculated from now on. The position can be reliably detected.

  In addition, since the thermal conductivity of the sensor 1 is 5 W / (m · K) to 15 W / (m · K), it can have a heating / cooling performance sufficient for practical use, and further has a high reactivity (accuracy). An excellent liquid level gauge 10 can be provided.

  Furthermore, since the sensor 1 has a length of 50 cm or more, the sensor 1 can be made longer than the conventional one, and it is not necessary to obtain a distance by connecting a plurality of sensors vertically even when the container is deep. Therefore, the level gauge 10 that can be used for a container having a depth can be provided.

The sensor 1 is a wire having an overall cross-sectional diameter of 0.5 mm to 2.0 mm, and the MgB ₂ layer occupies 30% to 60% of the cross-sectional area. It is possible to provide the level gauge 10 that can achieve performance and is further excellent in reactivity (accuracy).

  Next, a liquid level gauge for measuring an ultra-low temperature liquefied gas liquid level according to a modification of the first embodiment of the present invention will be described. FIG. 2 is a diagram showing an ultra-low temperature liquefied gas liquid level measuring sensor used in the ultra-low temperature liquefied gas liquid level measuring liquid level meter according to a modification of the first embodiment of the present invention. Note that description of the same parts as those in the first embodiment is omitted.

  An ultra-low temperature liquefied gas liquid level measuring liquid level meter according to a modification of the first embodiment includes an ultra-low temperature liquefied gas liquid level measuring sensor 1a (hereinafter referred to as sensor 1a) wound in a coil shape instead of the sensor 1. It is different from the liquid level gauge 10 of the first embodiment in that it is used.

According to this modification, the same operation and effect as the liquid level gauge 10 of the first embodiment can be obtained. Further, since the effective length of the sensor 1a can be increased, the difference in resistance value between the superconducting state portion and the normal conducting state portion in the MgB ₂ layer can be further increased. As a result, it is possible to provide a liquid level gauge for measuring a liquid level of an ultra-low temperature liquefied gas having a sensor 1a having further excellent reactivity (accuracy).

  Next, an ultra-low temperature liquefied gas liquid level measuring liquid level meter according to a second embodiment of the present invention will be described. FIG. 3 is a schematic configuration diagram of an ultra-low temperature liquefied gas liquid level measuring liquid level meter according to the second embodiment of the present invention. In addition, description may be abbreviate | omitted about the site | part (symbol 12-16, 18, 19 corresponding to the codes | symbols 2-6, 8, 9) similar to the said 1st Embodiment.

  As shown in FIG. 3, a liquid level gauge 20 for liquid level measurement of ultra-low temperature liquefied gas (hereinafter referred to as liquid level gauge 20) includes a sensor 11 for liquid level measurement of liquid cryogenic gas (hereinafter referred to as sensor 11) and a direct current. A current power source 12, a heater power source 13, a voltmeter 14, an arithmetic processing device 15, a monitor 16, a heater unit 17, a cylinder 18, and a fixing resin 19 are provided. FIG. 3 shows a state in which the cylinder 18 is partially immersed in the ultra-low temperature liquefied gas in the storage container (not shown) as in the first embodiment.

  The liquid level gauge 20 is different from the liquid level gauge 10 of the first embodiment in that the sensor 11 and the heater parts 17a and 17b are used instead of the sensor 1 and the heater part 7.

  The sensor 11 is fixed to the cylinder 18 by a fixing resin 19 in a state of being folded in a U shape, and an electrode can be easily taken at the upper part of the cylinder 18.

  The heater units 17 a and 17 b are arranged so as to heat both ends of the sensor 11 and are electrically connected to the heater power supply 13.

According to the liquid level gauge 20 having the above-described configuration, the same actions and effects as the liquid level gauge 10 of the first embodiment can be achieved. In addition, since the effective length of the sensor 11 can be increased, the difference in resistance value between the superconducting state portion and the normal conducting state portion in the MgB ₂ layer can be further increased. As a result, the liquid level meter 20 having the sensor 1 having further excellent reactivity (accuracy) can be obtained.

  Next, a liquid level gauge for measuring an ultra-low temperature liquefied gas liquid level according to a modification of the second embodiment of the present invention will be described. FIG. 4 is a diagram showing an ultra-low temperature liquefied gas liquid level measuring sensor used in an ultra-low temperature liquefied gas liquid level measuring liquid level meter according to a modification of the second embodiment of the present invention.

  An ultra-low temperature liquefied gas liquid level measuring liquid level meter according to a modification of the second embodiment includes an ultra-low temperature liquefied gas liquid level measuring sensor 11a (hereinafter referred to as sensor 11a) wound in a coil shape instead of the sensor 11. It is different from the liquid level gauge 20 of the second embodiment in that it is used.

According to this modification, the same operation and effect as the liquid level gauge 20 of the second embodiment can be achieved. In addition, since the effective length of the sensor 11a can be further increased, the difference in resistance value between the superconducting state portion and the normal conducting state portion in the MgB ₂ layer can be further increased. As a result, it is possible to provide a liquid level gauge for measuring a liquid level of an ultra-low temperature liquefied gas that has a sensor 11a having excellent reactivity (accuracy).

  Below, the liquid level gauge of the same structure as the liquid level gauge 10 which concerns on the said 1st Embodiment was produced, and the performance of this liquid level gauge was verified. Below, the concrete preparation method and verification method of the liquid level meter which concern on a present Example are demonstrated.

(Sensor production method)
A sensor was produced using the in-situ method among the PIT methods. Specifically, the mixed powder of Mg and B was packed in a Ni—Cu cylinder (Ni: Cu = 3: 7) serving as a coating layer, and after drawing, the shaft core portion was changed to MgB ₂ by heat treatment. . At this time, the diameter of the sensor is 0.65 mm, the length is 50 cm, and the diameter of the MgB ₂ layer is 0.36 mm (occupies 30% of the entire cross section of the sensor).

(Verification method of level gauge performance)
The temperature dependence of the electrical resistance of the fabricated sensor was investigated from room temperature to cryogenic temperature, and from cryogenic temperature to room temperature, and verified by measuring the superconducting transition temperature at which the electrical resistance was zero.

(inspection result)
As shown in FIG. 5, it can be seen that the resistance value suddenly changes around 34K. It can also be seen that the electrical resistance value is zero at 34K. Therefore, it can be seen that the sensor is sensitive around 34K. Therefore, it can be used as a sensor for a liquid level gauge for liquid level measurement of a cryogenic liquefied gas having a boiling point of 34K or less.

  The present invention can be changed in design without departing from the scope of the claims, and is not limited to the above-described embodiments and examples. The shape of the sensor in each of the above embodiments and examples may be a wave shape, or a single-core wire may be rolled into a tape shape. Alternatively, a single core wire may be bundled and drawn to form a multi-core sensor, or the multi-core sensor may be rolled into a tape shape.

It is a schematic block diagram of the liquid level meter for ultra-low temperature liquefied gas liquid level measurement concerning a 1st embodiment of the present invention. It is a figure which shows the sensor for ultra-low temperature liquefied gas liquid level measurement used for the liquid level gauge for ultra-low temperature liquefied gas liquid level measurement which concerns on the modification of 1st Embodiment of this invention. It is a schematic block diagram of the liquid level meter for ultra-low temperature liquefied gas liquid level measurement concerning a 1st embodiment of the present invention. It is a figure which shows the sensor for ultra-low temperature liquefied gas liquid level measurement used for the liquid level gauge for ultra-low temperature liquefied gas liquid level measurement which concerns on the modification of 2nd Embodiment of this invention. It is a graph which shows the verification result of the Example which concerns on this invention.

Claims (10)

An ultra-low temperature liquefied gas liquid level measuring sensor comprising a long superconductor containing MgB ₂ and a coated metal covering a surface of the superconductor. An ultra-low temperature liquefied gas liquid level measurement sensor comprising: a coiled superconductor containing MgB ₂ ; and a coated metal covering a surface of the superconductor.   The resistance value at normal temperature is 1 Ω / m to 5 Ω / m, and the sensor for measuring a liquid level of an ultra-low temperature liquefied gas according to claim 1 or 2.   The thermal conductivity is 5 W / (m · K) to 15 W / (m · K), the ultra-low temperature liquefied gas liquid level measurement sensor according to any one of claims 1 to 3.   The sensor for measuring the level of an ultra-low temperature liquefied gas according to any one of claims 1 to 4, wherein the length is 50 cm or more.   The diameter of the whole cross section is a wire of 0.5 mm to 2.0 mm, and the superconductor layer occupies 30% to 60% of the cross sectional area. Sensor for liquid level measurement of ultra-low temperature liquefied gas as described in 1.   The ultra-low temperature liquefied gas liquid level measurement sensor according to any one of claims 1 to 6, wherein the coating metal is a Ni-Cu alloy.   8. The ultra-low temperature liquefied gas liquid level measurement sensor according to claim 7, wherein the ratio of Ni to Cu in the coated metal is from 3: 7 to 4: 6.   The ultra-low temperature liquefied gas liquid level measuring sensor according to any one of claims 1 to 8, wherein the sensor is formed so as to be U-shaped as a whole.   10. The ultra-low temperature liquefied gas liquid level measurement sensor according to any one of claims 1 to 9, a heater for heating the ultra-low temperature liquefied gas liquid level measurement sensor, and the ultra-low temperature liquefied gas liquid level measurement sensor. And a voltmeter for measuring a voltage in the ultra-low temperature liquefied gas liquid level measuring sensor. A liquid level gauge for measuring an ultra-low temperature liquefied gas liquid level.

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