WO2006057220A1 - タンク内液体の漏れ検知装置 - Google Patents
タンク内液体の漏れ検知装置 Download PDFInfo
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- WO2006057220A1 WO2006057220A1 PCT/JP2005/021365 JP2005021365W WO2006057220A1 WO 2006057220 A1 WO2006057220 A1 WO 2006057220A1 JP 2005021365 W JP2005021365 W JP 2005021365W WO 2006057220 A1 WO2006057220 A1 WO 2006057220A1
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- Prior art keywords
- liquid
- tank
- measurement
- leak detection
- flow rate
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M3/00—Investigating fluid-tightness of structures
- G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
- G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors
- G01M3/32—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators
- G01M3/3236—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators by monitoring the interior space of the containers
- G01M3/3254—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators by monitoring the interior space of the containers using a flow detector
Definitions
- the present invention relates to an apparatus for detecting leakage of liquid in a tank, and more particularly to an apparatus for detecting liquid leakage from a tank by converting it into a flow based on fluctuations in the level of liquid in the tank.
- Fuel oil, various liquid chemicals, and the like are stored in a tank.
- the tank may crack due to deterioration over time, and in this case, the liquid in the tank leaks out of the tank. It is important to detect such a situation promptly and take appropriate measures to prevent a flammable explosion, environmental pollution, or generation of toxic gases.
- Patent Document 1 discloses a measuring tube into which liquid in a tank is introduced and a position below the measuring tube. And measuring the flow rate of the liquid in the measurement capillary using a sensor section attached to the measurement capillary, so that a minute liquid level fluctuation of the liquid in the tank, that is, a change in the liquid level is detected. What has been disclosed is disclosed.
- an indirectly heated flow meter is used as a sensor attached to a measurement thin tube.
- the heating element is heated by energization, and a part of the generated heat is absorbed by the liquid, and the effect of this endotherm is obtained by utilizing the fact that the endothermic amount of the liquid varies depending on the flow rate of the liquid. It is detected by the change of the electrical characteristic value due to the temperature change of the temperature sensor, for example, the resistance value.
- Patent Document 1 The leak detection device described in Patent Document 1 is inserted substantially vertically into a tank from a measuring port formed in the upper part of the tank. If this detector is used with its upper part fixed to the tank metering port, the measurement tube, measurement tube, sensor, etc. are fixed to the upper part of the tank.
- Patent Document 1 Japanese Patent Laid-Open No. 2003-185522
- Convection in the measuring capillary is not a problem when the fluidity of the liquid is low, that is, when the fluid has a high kinematic viscosity, but when the fluidity of the liquid is high, that is, the fluid kinematic viscosity. If the value is low, the flow measurement results may be significantly affected. For example, when the liquid is gasoline and the kinematic viscosity is low (when the temperature is 20 ° C and the kinematic viscosity is about 0.8 mm 2 / s), the convection generated in the measuring capillary can be ignored. As a result, the flow rate value measured by the indirectly heated flow meter will include a non-negligible contribution due to convection, which may reduce the accuracy of leak detection.
- an object of the present invention is to suppress a decrease in flow rate measurement accuracy by the indirectly heated flow meter even if the liquid in the tank is a low viscosity liquid, and for a long time without causing a decrease in detection accuracy. Accordingly, an object of the present invention is to provide a tank liquid leak detection device capable of accurately detecting a very small amount of leak.
- a device for detecting leakage of liquid in a tank A device for detecting leakage of liquid in a tank
- a measuring tube connected to the upper end of the measuring capillary and having a larger cross-sectional area than the measuring capillary, and a flow rate sensor attached to the measuring capillary for measuring the flow rate of the liquid in the measuring capillary.
- the flow sensor unit includes a heater and a temperature sensor, and the measuring thin tube has a distance from the position corresponding to the heater to the upper end opening of 20 mm or more and 45 mm or less. Detection device,
- the length of the measurement capillary is 30 mm or more and 65 mm or less. In one aspect of the present invention, the tube cross-sectional area of the measurement capillary is 5 m m 2 or less 0. 75 mm 2 or more.
- the measurement thin tube includes a first portion located in a package of the flow rate sensor portion and a second portion connected to an upper portion of the first portion.
- the second portion is attached to the package.
- the second portion extends into the measurement tube.
- the temperature sensor includes a first temperature sensor and a second temperature sensor, and the flow rate sensor unit is arranged in order along the measurement thin tube.
- the heater and the second temperature sensor are included.
- the apparatus further includes a leak detection control unit connected to the flow sensor unit, and the leak detection control unit applies a voltage to the heater.
- a leakage detection circuit connected to the first temperature sensor and the second temperature sensor and generating an output corresponding to a temperature difference sensed by the temperature sensors. Liquid leakage in the tank is detected based on a flow rate corresponding value corresponding to the liquid flow rate calculated using the output of the circuit.
- the apparatus further includes a pressure sensor for measuring the liquid level of the liquid, and the leak detection control unit further includes a liquid level measured by the pressure sensor. The leakage of the liquid in the tank is detected based on the magnitude of the change rate.
- the leak detection control unit when the leak detection control unit detects a leak of the liquid in the tank based on the magnitude of the time change rate of the liquid level, the magnitude of the time change rate of the liquid level.
- the value is within a predetermined range
- the result of leak detection is output
- the rate of time change of the liquid level is smaller than the lower limit of the predetermined range
- the result of leak detection based on the flow rate corresponding value is output.
- the output relating to leakage is stopped.
- the leak detection control unit when the leak detection control unit detects a liquid leak in the tank based on the magnitude of the time change rate of the liquid level, the magnitude of the time change rate of the liquid level is When the upper limit of the predetermined range is exceeded, leakage detection based on the flow rate corresponding value is stopped for a predetermined time.
- the liquid in the tank has a low viscosity. Even if it is a liquid, it is possible to suppress a decrease in the accuracy of flow measurement by the indirectly heated flow meter, and it is possible to accurately detect a very small amount of leakage over a long period of time without causing a decrease in detection accuracy.
- FIG. 1 is a partially broken perspective view for explaining an embodiment of a tank liquid leak detection device according to the present invention.
- FIG. 2 is a partially omitted cross-sectional view of the leak detection device of the embodiment of FIG.
- FIG. 3 is a partially enlarged view of FIG.
- FIG. 4 is an enlarged perspective view of a portion where a first temperature sensor, a heater and a second temperature sensor are attached to a measurement thin tube.
- FIG. 5 is a cross-sectional view of FIG.
- FIG. 6 is a diagram showing a circuit configuration of a flow rate sensor unit, a pressure sensor, and a leak detection control unit.
- FIG. 7 is a timing chart showing the relationship between the voltage Q applied to the thin film heating element and the voltage output S of the leak detection circuit.
- FIG. 8 is a diagram showing a specific example of the relationship between the voltage Q applied to the thin film heating element and the voltage output S of the leak detection circuit.
- FIG. 9 is a diagram showing a specific example of the relationship between the liquid level change rate and the integral value ⁇ (S 1 S) dt.
- FIG. 10 is a diagram showing a specific example of the relationship between the liquid level change rate and the time change rate P ′ of the liquid level corresponding output.
- FIG. 11 is a diagram showing an example of a calibration curve for conversion of the voltage output S of the leak detection circuit.
- FIG. 12 is a diagram showing experimental results in an embodiment of the present invention and a reference embodiment outside the scope of the present invention.
- FIG. 1 is a partially broken perspective view for explaining an embodiment of a leak detection apparatus for liquid in a tank according to the present invention
- FIG. 2 is a partially omitted sectional view of the leak detection apparatus of this embodiment
- Fig. 3 is a partially enlarged view.
- the tank 1 has a metering port 5 and a liquid injection port 6 used for injecting liquid into the tank.
- the top plate 2 is formed, the side plate 3 is formed with a liquid supply port 7 used when liquid is supplied from the inside of the tank to the outside of the tank, and the bottom plate 4 is provided.
- the tank 1 has a low dynamic viscosity combustible liquid such as liquid (eg gasoline or jet fuel [dynamic viscosity 1.2 mm 2 / s (about 20 ° C))].
- L is housed.
- LS indicates the liquid level.
- the leak detection device 11 is partially inserted into the tank 1 through the measuring port 5 formed in the top plate 2 of the tank 1, and is arranged in the vertical direction as a whole.
- the leak detection device 11 includes a liquid introduction / extraction section 12, a flow rate measurement section 13, a liquid reservoir section 14, a cap 16 and a circuit housing section 15.
- the liquid inlet / outlet part 12, the flow rate measuring part 13, and the liquid reservoir part 14 are located inside the tank 1, and the liquid level LS is located within the height range of the liquid reservoir part 14.
- the flow rate measuring unit 13 is configured to include a sheath tube 171 extending in the vertical direction
- the liquid reservoir unit 14 is configured to include a sheath tube 17 extending in the vertical direction. Les.
- a sensor holder 13a is disposed in the sheath tube 171, and the vertical measurement thin tube first portion 13b is fixedly held by the sensor holder.
- a first temperature sensor 133, a heater 135, and a second temperature sensor 134 are arranged and attached in this order from the upper side to the measurement capillary first portion 13b.
- the heater 135 is disposed at a position equidistant from the first temperature sensor 133 and the second temperature sensor 134. Since the outer side of the sensor holder 13a is covered with the sheath tube 171, the first temperature sensor 133, the heater 135, and the second temperature sensor 134 are protected from the corrosive force caused by the liquid L.
- the first temperature sensor 133, the heater 135, and the second temperature sensor 134 constitute a flow rate sensor unit for measuring the flow rate of the liquid in the measurement capillary first portion 13b, and are shown in FIG.
- the measurement thin tube first portion 13b is located in the flow rate sensor portion package 130, and its upper and lower end openings protrude from the package.
- the lower end portion of the measurement thin tube second portion 13b ′ is connected to the upper end opening of the measurement thin tube first portion 13b. That is, the second measuring thin tube portion 13b ′ is attached to the flow sensor portion package 130 and protrudes to the inside of the sheath tube 17 of the liquid reservoir portion 14 constituting the measuring tube.
- the upper end of the measurement capillary third portion 13b is connected to the lower end opening of the measurement capillary first portion 13b. That is, the measurement capillary third portion 13b" is attached to the flow sensor section receptacle 130. It communicates with the liquid inlet / outlet section 12. Part 1 above The measuring capillary consisting of the minute portion 13b to the third portion 13b "functions as a liquid flow path between the liquid reservoir portion 14 and the liquid inlet / outlet portion 12. In the present invention, the above-described form is also used.
- the measuring tube shall be connected to the upper end of the measuring tube.
- the flow rate measurement unit 13 is provided with a pressure sensor 137 attached to the sensor holder 13a in the vicinity of the lower end of the measurement thin tube third portion 13b ".
- the pressure sensor 137 is used for the liquid L in the tank.
- a piezo element or a condenser type pressure sensing element can be used, and an electric signal corresponding to the liquid level, for example, a voltage signal is output.
- the filter cover 12b fixes the filter 12a to the lower portion of the sensor holder 13a.
- the fineletter 12a has a function of removing foreign matters such as sludge that floats or settles on the liquid in the tank and introduces only the liquid to the liquid reservoir 14 through the measuring capillary. Further, an opening is provided in the side wall of the filter cover 12b, and the liquid L in the tank 1 is introduced into the measurement tube through the filter 12a of the liquid introduction / extraction part 12.
- the liquid reservoir 14 is located above the flow rate measuring unit 13, has a space G surrounded by the sheath tube 17, and stores the liquid introduced from the measurement capillary in the space G. It is configured.
- a cap 16 is fixed to the upper portion of the sheath tube 17, and an air passage 16 a is formed in the cap for communicating the inside of the liquid reservoir portion 14 with the space in the tank outside the detection device.
- a circuit housing portion 15 is attached to the cap 16, and a leak detection control portion 15 a is housed in the circuit housing portion.
- a guide pipe Pg extending so as to connect the upper part of the sensor holder 13a and the cap 16 is disposed in the sheath pipe 17, and the first temperature sensor 133, the heater 135, and the first pipe of the flow rate measurement unit 13 are disposed.
- the wiring 18 connecting the temperature sensor 134 and the pressure sensor 137 of 2 and the leak detection control unit 15a extends through the guide tube Pg.
- the sheath tube 17 in the liquid reservoir 14 constitutes the measurement tube of the present invention.
- the cross-sectional area of the measuring capillary, especially the first part 13b is sufficiently small compared to the internal cross-sectional area of the sheath pipe 17 (excluding the outer cross-sectional area of the guide pipe Pg). For example, 1/50 or less, 1/100 or less, Furthermore, by setting it, it is possible to generate a liquid flow that can measure the flow rate in the measuring capillary, particularly the first part 13b, even if the liquid level changes slightly when a slight liquid leaks.
- Measurement tube part 1 The cross-sectional area of the tube 13b is, for example, not less than 0.75 mm 2 and not more than 5 mm 2 .
- the in-tube cross-sectional areas of the measurement capillary first portion 13b 'and the measurement capillary third portion 13b may be equivalent to the in-tube cross-sectional area of the measurement capillary first portion 13b.
- the measurement narrow tube, sheath tube 17, 171, sensor holder 13a, filter cover 12b, cap 16 and guide tube Pg are preferably made of a metal having a thermal expansion coefficient close to that of the material constituting the tank 1. More preferably, it is made of the same metal as the material of tank 1 such as pig iron or stainless steel.
- FIG. 4 is an enlarged perspective view of a mounting portion of the first temperature sensor 133, the heater 135, and the second temperature sensor 134 with respect to the measurement thin tube
- FIG. 5 is a sectional view thereof.
- the heater 135 includes a heat transfer member 181 disposed in contact with the outer surface of the measurement thin tube first portion 13b, and a thin film heating element 182 laminated on the heat transfer member 181 via an electrically insulating thin film.
- the thin film heat generator 182 is formed in a required pattern, and a wire 182 ′ is connected to an electrode for energizing the thin film heat generator.
- the heat transfer member 181 is made of, for example, a metal or alloy having a thickness of about 0.2 mm and a width of about 2 mm.
- the wiring 182 ′ is connected to wiring (not shown) formed on the wiring board 24 such as a flexible wiring board. This wire is connected to the wire 18 in the guide tube Pg.
- the heat transfer member 181, the thin film heating element 182, and the wiring 182 ′ are sealed with a sealing member 23 made of a synthetic resin together with a part of the wiring substrate 24 and a part of the measuring thin tube 13 b.
- the first temperature sensor 133 and the second temperature sensor 134 have the same configuration as the heater 135 except that a thin film temperature sensing element is used instead of the thin film heating element.
- the liquid level LS of the liquid L in the tank is located within the height range of the liquid reservoir 14 as described above. Therefore, the pressure sensor 137 is immersed in the liquid L in the tank filtered by the filter 12a of the liquid introduction / extraction part 12, and the liquid L in the tank is also in the third portion 13b " Ascends through the first part 13b and the second part 13b 'and is introduced into the space G of the liquid reservoir 14, and finally the liquid level in the liquid reservoir 14 becomes liquid in the tank outside the leak detector.
- the liquid level of the liquid in the tank is higher than the upper end of the second part 13b 'of the measuring thin tube.
- FIG. 6 is a diagram showing a circuit configuration of the flow rate sensor unit, the pressure sensor, and the leak detection control unit.
- a battery (not shown) arranged in the circuit housing portion 15 can be used.
- the thin film heating element 182 of the heater 135 is connected to the voltage generation circuit 67.
- a pulse voltage generation circuit is used as the voltage generation circuit 67.
- a single pulse voltage is applied to the thin film heating element 182 from the pulse voltage generation circuit in a timely manner.
- the thin film temperature detectors 60 and 61 constituting the first and second temperature sensors 133 and 134 are connected to a leak detection circuit 71. That is, the thin film temperature sensors 60 and 61 constitute a bridge circuit together with the resistors 62 and 63.
- a power supply voltage VI is supplied to the bridge circuit, and a voltage output signal corresponding to the potential difference between points a and b is obtained by the differential amplifier 65.
- the output of the leak detection circuit 71 corresponds to the temperature difference detected by the thin film temperature sensors 60 and 61 of the temperature sensors 133 and 134, and is input to the CPU 68 via the A / D converter 66.
- the pulse voltage generation circuit 67 is controlled in accordance with a command from the CPU 68.
- the output of the pressure sensor 137 is input to the CPU 68 via the A / D converter 73.
- the CPU has a clock 69 and memory 70 power S connected.
- FIG. 7 is a timing chart showing the relationship between the voltage Q applied from the pulse voltage generation circuit 67 to the thin film heating element 182 and the voltage output S of the leak detection circuit 71.
- the CPU 68 is applied with a single pulse voltage having a width of tl based on the clock 69 at a predetermined time interval t2.
- This single pulse voltage has, for example, a pulse width tl of 2 to 10 seconds and a pulse height Vh of 1.5 to 4 V.
- the heat generated in the thin film heating element 182 heats the measurement capillary first portion 13b and the liquid inside thereof, and is transmitted to the surroundings. The effect of this heating reaches the thin film temperature sensors 60 and 61, and the temperature of these thin film temperature sensors changes.
- the temperature changes in the two temperature sensing elements 60 and 61 are equal if the contribution of heat transfer by convection is ignored.
- the liquid level of the liquid in the tank drops as when the liquid in the tank leaks from the tank, the liquid passes from the liquid reservoir 14 through the measuring capillary 13b into the tank outside the detector. Since it is led out from the inlet / outlet part 12, the liquid in the measuring capillary 13b flows from top to bottom. As a result, the heat from the thin film heating element 182 is increased. It is transmitted more toward the thin film temperature sensor 61 of the temperature sensor 134 on the lower side than the thin film temperature sensor 60 of the temperature sensor 133 on the side.
- FIG. 7 shows changes in the voltage VT1 applied to the thin film temperature sensor 60 of the temperature sensor 133 and the voltage VT2 applied to the thin film temperature sensor 61 of the temperature sensor 134.
- the output of the differential amplifier that is, the voltage output S of the leakage detection circuit 71 changes as shown in FIG.
- FIG. 8 shows a specific example of the relationship between the voltage Q applied to the thin film heating element 182 from the noiseless voltage generating circuit 67 and the voltage output S of the leak detection circuit 71.
- the single pulse voltage has a pulse height Vh of 2 V, a pulse width tl of 5 seconds, and a voltage output S [F] was obtained by changing the liquid level change rate F [mm / h]. .
- the leakage detection circuit In the CPU 68, according to the application of the single-noise voltage to the thin-film heating element 182 of the heater 135 by the pulse voltage generation circuit 67, the leakage detection circuit at a predetermined time t3 after the start of the single pulse voltage application. Integrate the difference (S — S) between the voltage output S and its initial value (ie, at the start of applying a single pulse voltage) S. This integral value ⁇ (S S) dt is the area shaded in FIG.
- the predetermined time t3 is, for example, 20 to 150 seconds.
- FIG. 9 shows a specific example of the relationship between the liquid level change rate corresponding to the flow rate F of the liquid in the measurement capillary first portion 13b and the integrated value ⁇ (S 1 S) dt.
- the constant time t3 was set to 30 seconds, and relationships at three different temperatures were obtained.
- Liquid level change rate 1.5 In the region of 5 mm / h or less, the temperature changes between the liquid level change rate and the integral value ⁇ (S 1 S) dt.
- a typical relationship between the integral value ⁇ (S_S) dt and the liquid level change rate is determined in advance in the memory 70.
- the stored value in the memory 70 is referred to based on the integral value ⁇ (S —S) dt that is a flow rate corresponding value calculated using the output of the leak detection circuit 71.
- the leakage of the liquid in the tank can be obtained as the liquid level change rate.
- a liquid level change rate smaller than a certain value for example, 0. Olmm / h
- This first leak detection is repeatedly performed at an appropriate time interval t2.
- the time t2 is, for example, 40 seconds to 5 minutes (however, longer than the integration time t3).
- the CPU 68 can immediately convert the liquid level corresponding output P input from the pressure sensor 137 via the A / D converter 73 into the liquid level p.
- the value of the liquid level p is based on the height of the pressure sensor 137.
- the height of the measuring port 5 of the force tank 1 and the distance from the attachment part of the leak detection device to the measuring port to the pressure sensor 137 Can be converted into a liquid level value for the tank itself.
- a liquid level detection signal indicating the result of the liquid level detection is output from the CPU 68.
- the CPU 68 stores the value of the liquid level p in the memory 70 every certain time tt, for example, 2 to 10 seconds, and calculates the difference from the previous stored value every time this storage is performed. Is stored in the memory 70 as the value of the time change rate p ′ of the liquid level.
- FIG. 10 shows a specific example of the relationship between the liquid level change rate and the time change rate P ′ of the liquid level corresponding output P.
- the rate of change P ′ corresponds well.
- a force showing a good linear relationship in the region where the liquid level change rate is 150 mm / h or less, and a good linear relationship in the region up to the liquid level change rate of 200 mm Zh should be obtained. Is possible.
- the leakage of the liquid in the tank can be obtained as the magnitude of the time change rate p ′ of the liquid level p measured by the pressure sensor 137.
- This second leak detection can cover a wider range of liquid level change speed than the first leak detection.
- the first leak detection can measure a minute liquid level change speed region with higher accuracy than the second leak detection.
- the liquid level change in the tank 1 also occurs when liquid is injected from the liquid injection port 6 into the tank or when liquid is supplied from the liquid supply port 7 to the outside.
- the rate of rise or fall of the liquid level in tank 1 in these cases is the same as the level change in case of a leak. In general, it is much larger than the rate of change of liquid or liquid level.
- the CPU 68 performs the following processing regarding leakage.
- the level of the liquid level time change rate p ' is within a predetermined range (for example, 10 to
- the second leak detection result is output as a leak detection signal.
- the CPU 68 can stop the first leak detection for the subsequent predetermined time tm.
- the predetermined time tm for stopping the leak detection is preferably slightly longer than the settling time of the liquid level LS after the liquid is injected into the tank from the outside or the liquid is supplied from the inside of the tank to the outside. For example, it can be 10-60 minutes.
- the CPU 68 can stop the operations of the pulse voltage generation circuit 67 and the leak detection circuit 71. According to this, power consumption is reduced.
- the liquid level change rate or the liquid level time change rate is related to the leak amount (leak amount per unit time). That is, the liquid level change rate or the liquid level time change rate multiplied by the horizontal sectional area inside the tank at the liquid level corresponds to the amount of liquid leakage. Accordingly, the shape of the tank (that is, the relationship between the height position and the horizontal cross-sectional area inside the tank) is stored in the memory 70 in advance, and the detection is performed as described above with reference to the stored content of this memory. Based on the liquid level and leakage (liquid level change rate or liquid level time change rate), the amount of liquid leakage in the tank can be calculated.
- the tank has a constant horizontal cross-sectional area regardless of the height, such as the vertical cylindrical shape shown in Fig. 1, the liquid level change rate or the liquid level time change
- the rate and leak rate are in a simple proportional relationship. Therefore, it is easy to multiply the rate of change of the liquid level or the rate of change of the liquid level time by a proportional constant according to the horizontal cross-sectional area inside the tank regardless of the liquid level value itself.
- the amount of leakage can be calculated. In other words, in this case, the leakage detected by the above-described apparatus of the present invention is substantially the same as that based on the leakage amount.
- the distance L1 from the position corresponding to the heater 135 to the opening at the upper end is 2 in the measurement capillary. Omm is 45mm or less. Further, the length of the measuring capillary (that is, the distance from the lower end opening force of the third portion 13b "to the upper end opening of the second portion 13b ') L2 is set to 30 mm or more and 65 mm or less.
- the distance L1 on the upper side from the position corresponding to the heater 135 is set to 20 mm or more, when the kinematic viscosity of the liquid is relatively low, for example, gasoline or jet fuel Even when the kinematic viscosity is 1.5 mm 2 / s [20 ° C] or less, the liquid in the measurement capillary is heated by the heater due to the pressure loss in the measurement capillary, especially above the heater 135. Even when heated, the convection generated in the measuring capillary is small. For this reason, the influence of convection on the flow rate measurement can be ignored, and a small amount of leakage can be detected without compromising the detection accuracy.
- the distance L1 on the upper side from the position corresponding to the heater 135 is set to 45 mm or less. Therefore, the pressure loss does not become too large, and the liquid level range in which leakage can be detected is not too narrow. Leak detection is possible.
- the length L2 of the measurement capillary is 30 mm or more, even in the case where the kinematic viscosity of the liquid is relatively low, due to the action of pressure loss in the measurement capillary, The generated convection is small. For this reason, the influence of convection on the flow rate measurement can be ignored, and it is possible to detect a small amount of leak without compromising the detection accuracy.
- the length L2 of the measuring capillary is 65 mm or less, the pressure loss does not become too large, and the liquid level range in which leakage can be detected is not too narrow, so that good leakage detection can be achieved. Is possible.
- FIG. 11 shows the experimental results regarding the difference in the influence of the convection in the flow rate measurement between the embodiment of the present invention as described above and the reference embodiment outside the scope of the present invention.
- Figure 11 (A) shows the present invention. Is due embodiments, L1 is 36. 5 mm, L2 is 50. 5 mm, the tube cross-sectional area of the measuring capillary, the first portion 13b is 0. 95 mm 2, the second portion 13b 'is 0. 95 mm 2 The third part 1 3b "was 0.95 mm 2. Gasoline was used as the liquid.
- Fig. 11 (B) is based on the reference form, except that the length of the second part of the measurement capillary is 22 cm shorter than that of the embodiment of the present invention so that it does not extend into the measurement pipe. It was the same as that of the embodiment of the invention. That is, L1 was 14.5 mm and L2 was 28.5 mm. Similar to the embodiment of the present invention, the time average value of the integral value ⁇ (S — S) dt (previous 3) under the condition that the liquid does not actually leak from the tank and the liquid level does not fluctuate.
- V voltage output
- a pulse voltage generation circuit is used as the voltage generation circuit 67.
- a constant voltage that is, a constant DC voltage
- such an embodiment will be described.
- a DC constant voltage Q is applied to the thin film heating element 182 of the heater 135 from the constant voltage generating circuit used as the voltage generating circuit 67 in FIG.
- the heater 135 maintains a constant heat generation state, and a part of the heat is transferred to the liquid in the measuring capillary 13b through the heat transfer member 181 and used as a heat source for heating the liquid. .
- the first and second temperature sensors can be ignored if the contribution of heat transfer by convection is ignored.
- the detected temperatures of 133 and 134 are substantially the same. However, if liquid circulation occurs in the measuring thin tube 13b, the influence of the liquid heating by the heater 135 is more strongly generated in the downstream side than in the upstream side. Therefore, the detection temperatures of the first and second temperature sensors 133 and 134 are increased. Become different from each other. Since the voltage output corresponding to the difference between the detected temperatures of the first and second temperature sensors 133 and 134 corresponds to the fluid flow rate, it is used as the flow rate value output.
- the bridge of the leak detection circuit 71 The potentials at points a and b of the circuit are input to the differential amplifier circuit 65.
- a voltage output S corresponding to the difference between the detected temperatures of the first and second temperature sensors 133 and 134 is obtained from the differential amplifier circuit by appropriately setting the resistance values of the resistors 6 2 and 63 of the bridge circuit in advance. be able to.
- the two-point temperature difference detection type flow rate measurement in the present invention is a temperature difference detected by the first and second temperature sensors arranged on the upstream side and the downstream side of the heater, respectively (actually corresponding to the detected temperature difference).
- the flow rate corresponding value is obtained based on the difference in the electrical characteristics detected in this way.
- the leak detection operation in this embodiment that is, the operation of the CPU 68 will be described.
- the operation of the CPU 68 of this embodiment is different from that of the embodiment described above with reference to FIGS. 1 to 11 only in the first leak detection operation, and the other operations are the same.
- the CPU 68 performs conversion to the corresponding flow rate value using the built-in calibration curve based on the voltage output S.
- Figure 12 shows an example of a calibration curve for S conversion. As shown in Fig. 12, in the region where the liquid level change rate corresponding to the flow rate value is smaller than 10 mm / h, for example, a good linear correspondence between the liquid level change rate and the voltage output S is obtained. There is. Therefore, the CPU 68 can perform processing similar to that of the embodiment described with reference to FIGS.
- the present embodiment has an advantage that the calculation for obtaining the flow rate corresponding value in the first leak detection in the CPU 68 is simplified as compared with the embodiment described with reference to Figs.
- FIG. 12 shows the experimental results regarding the difference in the influence of the convection in the flow rate measurement between the embodiment of the present invention as described above and the reference embodiment outside the scope of the present invention.
- FIG. 12 (A) is according to the embodiment of the present invention, L1 is 36.5 mm, L2 is 50.5 mm, and the cross-sectional area of the measuring capillary is 0.95 mm 2 in the first portion 13b. Part 13b 'was 0.95 mm 2 and part 1 3b "was 0.95 mm 2. Gasoline was used as the liquid. Conditions under which there was no actual leakage of liquid from the tank and no liquid level fluctuations Fig. 12 shows the voltage output S and the average voltage output Sa for 300 seconds just before that obtained in Fig. 12.
- Embodiment of the present invention except that the length of the second portion is 22 mm shorter than that of the embodiment of the present invention so that it does not extend into the measuring tube. Like the ones. That is, L1 was 14.5 mm and L2 was 28.5 mm. Similar to the embodiment of the present invention, the voltage output S and the average voltage output Sa for 300 seconds immediately before the voltage output S are shown under the condition that there is no actual leakage of liquid from the tank and there is no liquid level fluctuation. It can be seen that the fluctuations of S and Sa are larger than those of the embodiment of the present invention, and are likely to be a cause of a decrease in leak detection accuracy.
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- Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
- Measuring Volume Flow (AREA)
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US11/791,881 US7647820B2 (en) | 2004-11-29 | 2005-11-21 | Device for detecting leakage of liquid in tank |
Applications Claiming Priority (2)
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JP2004344108A JP2006153634A (ja) | 2004-11-29 | 2004-11-29 | タンク内液体の漏れ検知装置 |
JP2004-344108 | 2004-11-29 |
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WO2006057220A1 true WO2006057220A1 (ja) | 2006-06-01 |
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PCT/JP2005/021365 WO2006057220A1 (ja) | 2004-11-29 | 2005-11-21 | タンク内液体の漏れ検知装置 |
Country Status (3)
Country | Link |
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US (1) | US7647820B2 (ja) |
JP (1) | JP2006153634A (ja) |
WO (1) | WO2006057220A1 (ja) |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006153635A (ja) * | 2004-11-29 | 2006-06-15 | Mitsui Mining & Smelting Co Ltd | タンク内液体の漏れ検知装置 |
CN103344173B (zh) * | 2013-07-04 | 2018-01-05 | 吉林大学 | 地下换热器的管土间隙辨识方法 |
GB2553681B (en) | 2015-01-07 | 2019-06-26 | Homeserve Plc | Flow detection device |
GB201501935D0 (en) | 2015-02-05 | 2015-03-25 | Tooms Moore Consulting Ltd And Trow Consulting Ltd | Water flow analysis |
CN113303305B (zh) * | 2021-05-14 | 2022-02-11 | 北京百瑞盛田环保科技发展有限公司 | 一种施药监控方法、装置及系统 |
US11808663B2 (en) | 2021-06-09 | 2023-11-07 | Saudi Arabian Oil Company | In situ leakage detection system for buried nonmetallic pipeline |
CN117963370A (zh) * | 2024-03-29 | 2024-05-03 | 四川惠科达仪表制造有限公司 | 一种多功能液位计 |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5886429A (ja) * | 1981-11-18 | 1983-05-24 | Toshiba Corp | タンク漏洩検出装置 |
JPH11190647A (ja) * | 1997-12-26 | 1999-07-13 | Tokyo Gas Co Ltd | 熱式フローセンサを利用した流量計及びそれを利用したガスメータ |
JP2001304934A (ja) * | 2000-03-30 | 2001-10-31 | Berkin Bv | 質量流量計 |
US6595049B1 (en) * | 1999-06-18 | 2003-07-22 | Mks Instruments, Inc. | Thermal mass flow sensor with improved sensitivity and response time |
JP2003214974A (ja) * | 2002-01-18 | 2003-07-30 | Mitsui Mining & Smelting Co Ltd | タンク内液体の漏れ検知装置 |
JP2003302271A (ja) * | 2002-04-08 | 2003-10-24 | Mitsui Mining & Smelting Co Ltd | 流量測定部パッケージ及びそれを用いた流量測定ユニット |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5086644A (en) * | 1990-11-01 | 1992-02-11 | Environmental Protection Technology, Inc. | Ultra sensitive leak detection |
JP3805244B2 (ja) | 2001-12-14 | 2006-08-02 | 三井金属鉱業株式会社 | タンク内液体の漏れ検知装置 |
US6920778B2 (en) * | 2001-12-14 | 2005-07-26 | Mitsui Mining & Smelting Co., Ltd. | Device for detecting leakage of liquid in tank |
WO2005043104A1 (ja) * | 2003-10-31 | 2005-05-12 | Mitsui Mining & Smelting Co., Ltd. | タンク内液体の漏れ検知装置 |
JP2006153635A (ja) * | 2004-11-29 | 2006-06-15 | Mitsui Mining & Smelting Co Ltd | タンク内液体の漏れ検知装置 |
-
2004
- 2004-11-29 JP JP2004344108A patent/JP2006153634A/ja active Pending
-
2005
- 2005-11-21 US US11/791,881 patent/US7647820B2/en not_active Expired - Fee Related
- 2005-11-21 WO PCT/JP2005/021365 patent/WO2006057220A1/ja active Application Filing
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5886429A (ja) * | 1981-11-18 | 1983-05-24 | Toshiba Corp | タンク漏洩検出装置 |
JPH11190647A (ja) * | 1997-12-26 | 1999-07-13 | Tokyo Gas Co Ltd | 熱式フローセンサを利用した流量計及びそれを利用したガスメータ |
US6595049B1 (en) * | 1999-06-18 | 2003-07-22 | Mks Instruments, Inc. | Thermal mass flow sensor with improved sensitivity and response time |
JP2001304934A (ja) * | 2000-03-30 | 2001-10-31 | Berkin Bv | 質量流量計 |
JP2003214974A (ja) * | 2002-01-18 | 2003-07-30 | Mitsui Mining & Smelting Co Ltd | タンク内液体の漏れ検知装置 |
JP2003302271A (ja) * | 2002-04-08 | 2003-10-24 | Mitsui Mining & Smelting Co Ltd | 流量測定部パッケージ及びそれを用いた流量測定ユニット |
Also Published As
Publication number | Publication date |
---|---|
US7647820B2 (en) | 2010-01-19 |
US20080115565A1 (en) | 2008-05-22 |
JP2006153634A (ja) | 2006-06-15 |
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