JP6653161B2 - Water level measurement system - Google Patents

Description

  The present invention relates to a water level measurement system for measuring a water level of a liquid container, a liquid tank, or the like, and particularly to a water level measurement system for measuring a water level using a thermocouple with a heater.

  A water level measurement system using a thermocouple with a heater is used to detect the water level of a liquid container or a liquid tank in a high-temperature environment. A thermocouple with a heater is a thermocouple made of a nickel-chromium heating wire and a thermocouple made of chromel alumel, etc., housed in a metal sheath, and each wire is filled with an insulating material such as magnesium oxide or alumina. Excellent heat resistance and environmental resistance. When using a thermocouple with a heater to measure the water level in a liquid container or liquid tank, a current is applied to the heater to heat the tip (sensor) of the thermocouple with a heater, and the thermoelectromotive force generated by the thermocouple Measure the signal. When the sensor section is underwater, the heat of the heater is easily dissipated to the outside of the metal sheath (the heat transfer rate from the sensor section to the surroundings is large), so that the temperature rise of the sensor section is suppressed. On the other hand, when the sensor unit is in the air (in the air or in steam), it is difficult for the heat of the heater to radiate to the outside of the metal sheath (the heat transfer coefficient from the sensor unit to the surroundings decreases). The temperature rise increases. The temperature rise of the sensor unit is compared with a predetermined determination value. If the temperature rise is larger than the determination value, it is determined that the water level is higher than the sensor unit. Further, by providing a plurality of thermocouples with heaters and arranging the respective sensor units at different heights, the water level can be measured stepwise.

  As a thermocouple with a sheath used for a water level measurement system, for example, there is one described in Patent Document 1. Patent Literature 1 discloses a detecting unit having a thermocouple and a heater, a sleeve for housing the detecting unit, and an outer side of the sleeve and near an upper side of a housing position of the detecting unit. A water level gauge is provided, comprising: a water drop relief part for separating water drops flowing down from outside the sleeve from above and flowing down from the sleeve and dropping the water drops.

  As a method for securing the earthquake resistance and shock resistance of such a thermocouple with a heater, there are a method of increasing the rigidity of the thermocouple with a heater by increasing the diameter and the thickness of the metal sheath, and a method of increasing the rigidity of the liquid container or the liquid tank. A method of arranging a thermocouple with a heater inside a protective tube fixed inside can be considered. However, when the diameter of the metal sheath is increased, the capacity of the sensor unit of the thermocouple with a heater increases, so that the required power supply capacity of the heater increases and the thermal responsiveness of the sensor unit decreases. . On the other hand, when the thermocouple with a heater is disposed in the protection tube, the protection tube secures the earthquake resistance and the shock resistance, so that the diameter of the thermocouple with the heater can be reduced. By reducing the diameter of the metal sheath and reducing the volume of the sensor unit of the thermocouple with a heater, the required power supply capacity of the heater can be suppressed, and the thermal responsiveness of the sensor unit can be improved.

JP-A-2005-055576

  When a thermocouple with a heater is installed in a protective tube, it is necessary to separate the sensor portion so that the sensor portion does not thermally contact the inner wall of the protective tube. This is because, when the sensor unit is in thermal contact with the inner wall of the protective tube, the heat of the heater is dissipated from the contact portion to the protective tube, thereby suppressing the temperature rise of the sensor unit even though it is not underwater. This is because there is a possibility that the sensor unit is erroneously determined to be underwater. As a method of thermally separating the sensor portion from the inner wall of the protection tube, a method of providing a plurality of spacers in the protection tube and inserting a thermocouple with a heater through the holes of the plurality of spacers is considered.

  However, it is extremely difficult to pass a thermocouple with a heater, which is bent due to a reduction in diameter, through holes of a plurality of spacers provided in a long protective tube. On the other hand, by reducing the number of spacers installed or adjusting the locations where the spacers are installed, this difficulty is reduced, but depending on the degree of bending of the heater-coupled thermocouple, the sensor section can contact the inner wall of the protective tube. The nature increases. Therefore, when the thermocouple with a heater breaks down, the thermocouple with the heater must be replaced after removing the protective tube from the liquid container or the liquid tank, and replacement work requires a great deal of labor and labor.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to prevent erroneous detection of a water level by a thermocouple with a heater installed in a protective tube and protect the liquid from a liquid container or a liquid tank. It is an object of the present invention to provide a water level measuring system capable of easily replacing a thermocouple with a heater without removing a pipe.

In order to solve the above-mentioned problem, the present invention provides a thermocouple with a heater in which a heater and a thermocouple arranged in close proximity to each other are housed in a sheath, and the heater is fixed inside a water tank open to the atmosphere, In a water level measurement system including a protection tube accommodating one thermocouple with a heater, a heater power supply for supplying power to the heater, and a voltage measurement circuit for measuring an electromotive force of the thermocouple, And an upper peripheral projection having an outer diameter smaller than the inner diameter of the protective tube, the upper peripheral protrusion being provided above a sensor unit in which the heater and the thermocouple are built, and the protective tube being provided below the sensor unit. And a lower peripheral projection having an outer diameter smaller than the inner diameter of the sensor tube, and an outer peripheral surface of the sensor portion is exposed to an inner wall of the protection tube .

  ADVANTAGE OF THE INVENTION According to this invention, in the water level measurement system which measures a water level with the thermocouple with a heater installed in the protective tube, while improving the reliability of a water level measurement, it becomes possible to easily replace the thermocouple with a heater. .

1 is an overall configuration diagram of a water level measurement system according to a first embodiment of the present invention. It is a vertical sectional view and a horizontal sectional view near the sensor of the thermocouple with a heater in the first embodiment of the present invention. FIG. 9 is a view showing a modification of the upper peripheral projection in the first embodiment of the present invention. It is a figure showing the modification of the lower circumference projection in a 1st example of the present invention. It is a figure showing an example of composition of a cable which connects a thermocouple with a heater and a water level measuring device in a 1st example of the present invention. FIG. 4 is a flowchart illustrating an operation of the water level measuring device according to the first embodiment of the present invention. It is the vertical sectional view and horizontal sectional view near the sensor of the thermocouple with a heater in a 2nd example of the present invention. FIG. 11 is an overall configuration diagram of a water level measurement system according to a third embodiment of the present invention. It is a flowchart which shows operation | movement of the water level measuring apparatus in the 3rd Example of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the drawings, the same members are denoted by the same reference numerals, and redundant description will be omitted as appropriate.

  FIG. 1 is an overall configuration diagram of a water level measurement system according to a first embodiment of the present invention. The water level measurement system 1 in the present embodiment measures the water level of the water tank 2 using a thermocouple 5 with a heater.

  The water level measurement system 1 includes a protection tube 4 fixed via a plurality of support members 3 inside a water tank 2 opened to the atmosphere, a thermocouple with a heater 5 housed in the protection tube 4, and a thermocouple with a heater. And a water level measuring device 6 for measuring a water level based on the thermoelectromotive force signal received from the control unit 5. The upper end of the thermocouple with heater 5 is connected to one end of a cable 8 via a connector 7, and the other end of the cable 8 is connected to a water level measuring device 6 via a connector 9. The water level measuring device 6 is connected with a display device 10 and a lamp 11 for notifying the measurement result.

  The upper end of the thermocouple with heater 5 is fixed to the upper end of the protective tube 4 via a fixing jig 12. The lower end of the thermocouple with heater 5 has a built-in heater 13 and thermocouple 14 (see FIG. 2), and forms a sensor unit 15. An upper peripheral projection 16 and a lower peripheral projection 17 projecting toward the inner peripheral surface of the protection tube 4 are provided on the upper side and the lower side of the sensor section 15, respectively.

  The length of the thermocouple with heater 5 is set such that the sensor unit 15 is arranged at a predetermined height in the water tank 2 when the thermocouple with heater 5 is installed in the protective tube 4. The length of the protection tube 4 is set so that the sensor unit 15 is arranged near the lower opening in the protection tube 4 when the thermocouple with heater 5 is installed in the protection tube 4. .

  The water level measurement device 6 includes a heater power supply 18, a voltage measurement circuit 19, and a measurement control circuit 20. The heater power supply 18 supplies power to the heater 13 (see FIG. 2) built in the sensor unit 15 via power lines 32a and 32b (see FIG. 5) housed in the cable 8. The voltage measurement circuit 19 measures a thermoelectromotive force signal generated by the thermocouple 14 of the sensor unit 15 via thermocouple wires 31a and 31b (see FIG. 5) accommodated in the cable 8, and converts the signal into a temperature. . The measurement control circuit 20 is connected to the heater power supply 18 and the voltage measurement circuit 19 via a control line, sends an ON / OFF command to the heater power supply 18, and sends a measurement command to the voltage measurement circuit 19. Send Further, the measurement control circuit 20 is connected to the display device 10 and the lamp 11, transmits a measurement result to the display device 10, and turns on or off the lamp 11 according to the measurement result. The display device 10 displays the measurement result received from the measurement control circuit 20 on the screen 23.

  FIGS. 2A and 2B are a vertical sectional view and a horizontal sectional view of the vicinity of the sensor section 15 of the thermocouple with heater 5, respectively. The heater 13 and the thermocouple 14 are disposed close to each other within a lower end of a sheath 25 made of stainless steel or a nickel alloy, and are made of an insulating material 24 made of powder such as alumina or magnesium oxide filled in the sheath 25. It is electrically insulated. As the heater 13, a nickel chrome heating wire is used, but other heating wires may be used. As the thermocouple 14, a chromel alumel (a chromel wire 22a and an alumel wire 22b joined at the ends) is used, but any thermocouple that can cover the temperature obtained by adding the temperature rise due to the heater heating to the water temperature. Other than chromel alumel (eg, copper constantan) can also be used. Heater leads 21a and 21b made of copper wire are connected to both ends of the heater 13, respectively.

  An upper peripheral projection 16 and a lower peripheral projection 17 projecting toward the inner peripheral surface of the protection tube 4 are provided on the upper side and the lower side of the sensor section 15, respectively. The outer diameters of the upper peripheral protrusion 16 and the lower peripheral protrusion 17 are set smaller than the inner diameter of the protective tube 4, and when the thermocouple with heater 5 is installed in the protective tube 4, the upper peripheral protrusion 16 and the lower peripheral protrusion 17 Gaps 26 and 27 are secured between the outer peripheral end of the side peripheral projection 17 and the inner wall of the protection tube 4. The upper peripheral projection 16 is formed such that the outer peripheral end of the lower side surface is inclined downward toward the inner wall of the protection tube 4. As a result, water droplets condensed on the outer peripheral surface of the sheath 25 above the sensor unit 15 travel along the upper surface of the upper peripheral protrusion 16 and separate from the outer peripheral surface of the sheath 25, and then travel along the lower surface of the upper peripheral protrusion 16. The arrival at the surface of the sensor unit 15 is suppressed. The upper side surface of the lower peripheral projection 17 is formed so as to be inclined downward toward the inner wall of the protection tube 4. This makes it possible to quickly separate water drops that have fallen along the surface of the sensor unit 15 from the surface of the sensor unit 15.

  FIG. 3 shows a modification of the upper peripheral projection 16. The upper peripheral projection 16A in this modification has a hollow cone 28 whose upper part is cut, and a cylindrical body 29 joined to the lower opening of the hollow cone 28, and the upper opening of the hollow cone 28 is It is joined to the outer peripheral surface of the sheath 25 via the welding portion 30. According to the upper peripheral projection 16 </ b> A of the present modification, the water droplets flowing down along the outer peripheral surface of the sheath 25 above the sensor section 15 are formed by the hollow cone 28 formed so as to incline downward toward the inner wall of the protective tube 4. It can be separated from the outer peripheral surface of the sheath 25 along the upper side surface, and can be quickly dropped along the outer peripheral surface of the cylindrical body 29, so that it is possible to further prevent water droplets from adhering to the surface of the sensor unit 15.

  FIG. 4 shows a modification of the lower peripheral projection 17. The lower peripheral projection 17A in this modification is formed such that the lower side surface is inclined upward toward the inner wall of the protection tube 4. Thereby, the sticking or friction when the thermocouple with heater 5 is inserted into the protective tube 4 is reduced, and the bend or breakage of the thermocouple with heater 5 can be prevented.

  FIG. 5 is a diagram showing an example of the configuration of the cable 8 that connects the thermocouple with heater 5 and the water level measuring device 6. The cable 8 is composed of two-core compensating conductors 31a and 31b (chromel wire 31a and alumel wire 31b) for transmitting the electromotive force of the thermocouple, and two-core power supply wires 32a and 32b made of copper wire. It is a multi-core cable. The chromel wire 31a and the alumel wire 31b are connected to the chromel wire 22a and the alumel wire 22b of the thermocouple 14 via the connector 7, respectively, and the power supply wires 32a and 32b are connected via the connector 7 to the heater lead wires 21a and 21b (FIG. 2). The compensating lead wires 31a and 31b and the power supply wires 32a and 32b are insulated from each other by a resin material 33 such as polyethylene.

  Next, the operation of the water level measuring device 6 in this embodiment will be described with reference to FIG.

  When the water level measurement device 6 is operated, the measurement control circuit 20 transmits a measurement command to the voltage measurement circuit 19 (Step S101).

  The voltage measurement circuit 19 that has received the measurement command from the measurement control circuit 20 measures the thermoelectromotive force signal generated by the thermocouple 14 of the sensor unit 15, and transmits the measured value to the measurement control circuit 20 (Step S102).

  The measurement control circuit 20 converts the measured value of the thermoelectromotive force signal received from the voltage measurement circuit 19 into a temperature (hereinafter, referred to as “pre-energization temperature”) T0 and holds the converted value (step S103). Is transmitted (step S104).

  Upon receiving the ON command from the measurement control circuit 20, the heater power supply 18 applies a predetermined current (for example, 1 A) to the heater 13 of the sensor unit 15 for a predetermined time (for example, 30 seconds) (Step S105).

  The measurement control circuit 20 transmits an OFF command to the heater power supply 18 when a predetermined time has elapsed after the ON command was transmitted to the heater power supply 18 (after the power supply to the heater 13 was started) (to the heater 13). Immediately after that, the measurement command is transmitted to the voltage measurement circuit 19 (step S106).

  The voltage measurement circuit 19 that has received the measurement command from the measurement control circuit 20 measures the thermoelectromotive force signal generated by the thermocouple 14 of the sensor unit 15, and transmits the measured value to the measurement control circuit 20 (Step S107).

  The measurement control circuit 20 converts the measured value of the thermoelectromotive force signal received from the voltage measurement circuit 19 into a temperature (hereinafter, referred to as “temperature after energization”) T1 and holds the converted value (step S108).

  The measurement control circuit 20 compares a difference (= T1−T0) between the temperature before energization (= T0) and the temperature after energization (= T1) with a predetermined determination value (Step S109), and is larger than the predetermined determination value. In this case, it is determined that the sensor unit 15 is in the air (the water level is lower than the sensor unit 15) (step S110), and when it is smaller, it is determined that the sensor unit 15 is in the water (the water level is higher than the sensor unit 15) ( Step S111).

  The measurement control circuit 20 turns on or off the lamp 11 according to the determination result (step S112), transmits the water level information based on the determination result to the display device 10, and causes the screen 23 to display the water level information (step S113).

  The water level measuring device 6 can monitor the water level of the water tank 2 by repeatedly performing the above-described series of processes (steps S101 to S113) at a constant cycle.

  If the sensor 15 of the thermocouple with heater 5 is in contact with the inner wall of the protection tube 4 during the above-described operation, the heat generated by the heater 13 while the heater power supply 18 is turned on is generated by the protection tube 4. And the temperature rise of the sensor unit 15 is suppressed, and the measurement control circuit 20 may erroneously determine that the sensor unit 15 is underwater. However, in this embodiment, since the upper peripheral projection 16 and the lower peripheral projection 17 provide a gap between the sensor unit 15 and the inner wall of the protection tube 4, the sensor unit 15 comes into contact with the inner wall of the protection tube 4. Therefore, the heat of the heater 13 can be prevented from being dissipated to the protection tube 4.

  Next, the replacement procedure of the thermocouple with heater 5 when the sensor unit 15 of the thermocouple with heater 5 fails will be described.

  (1) When the failure of the sensor unit 15 is detected, first, the operation of the water level measuring device 6 is stopped. The failure of the sensor unit 15 may be caused by the fact that the temperature change measured by the voltage measuring circuit 19 while the heater power supply 18 is turned on is different from the normal state, or the voltage and current (not shown) provided in the heater power supply 18. It can be detected because the measured value of the monitor is different from the normal value.

  (2) Remove the connector 7 of the cable 8 from the upper end of the thermocouple with heater 5 and remove the fixing jig 12 while supporting the upper end of the thermocouple with heater 5.

  (3) Pull out the thermocouple with heater 5 from the protection tube 4 upward.

  (4) Insert a new thermocouple 5 with a heater into the protection tube 4 and fix it to the protection tube 4 with the fixing jig 12. At this time, even when the thermocouple with heater 5 has a small diameter and has a bend, the upper peripheral projection 16 and the lower peripheral projection 17 secure a gap between the inner wall of the protective tube 4 and the sensor unit 15. There is no possibility that the portion 15 is damaged by contacting the inner wall of the protection tube 4. Further, since the outer diameter of the upper peripheral projection 16 and the lower peripheral projection 17 is smaller than the inner diameter of the protection tube 4, the thermocouple with heater 5 can be easily inserted into the protection tube 4.

  (5) Connect the connector 7 of the cable 8 to the upper end of the thermocouple with heater 5 and restart the operation of the water level measuring device 6.

  According to the water level measurement system 1 in the present embodiment, the upper peripheral projection 16 and the lower peripheral projection 17 are provided on the upper side and the lower side of the sensor section 15, respectively, so that the sensor section 15 comes into contact with the inner wall of the protection tube 4. Therefore, erroneous detection of the water level by the thermocouple with heater 5 accommodated in the protection tube 4 can be prevented. Further, since the upper peripheral protrusion 16 and the lower peripheral protrusion 17 are not fixed to the inner wall of the protective tube 4 and the outer diameters of the upper peripheral protrusion 16 and the lower peripheral protrusion 17 are smaller than the inner diameter of the protective tube 4, The thermocouple with heater 5 can be easily replaced while the protection tube 4 is fixed to the inner wall of the water tank 2.

  FIG. 7 is a cross-sectional view near the sensor unit 15 of the water level measurement system 1 according to the second embodiment of the present invention. In the water level measurement system 1 according to the present embodiment, a plurality of water holes 34 are provided in a part of the protective tube 4 that covers the sensor unit 15 (between the upper peripheral protrusion 16 and the lower peripheral protrusion 17). This is different from the first embodiment (see FIG. 2).

  In the water level measurement system 1 according to the present embodiment, when the water level of the water tank 2 rises and a part of the protection tube 4 covering the sensor unit 15 is flooded, the gap 27 between the lower peripheral projection 17 and the inner wall of the protection tube 4 and The liquid enters the periphery of the sensor unit 15 through the plurality of water holes 34. On the other hand, when the water level of the water tank 2 is lowered and a part of the protective tube 4 covering the sensor unit 15 is exposed on the water surface, the water around the sensor unit 15 is reduced by the lower peripheral projection 17 and the protective tube 4. The water is discharged to the outside of the protection tube 4 from the gap 27 with the inner wall and the plurality of water holes 34.

  In the water level measurement system 1 according to the present embodiment, the same effect as that of the first embodiment can be achieved. Further, by providing a plurality of water holes 34 in a part of the protective tube 4 covering the sensor portion 15 (between the upper peripheral protrusion 16 and the lower peripheral protrusion 17), the protective tube near the sensor portion 15 is provided. Since the water levels inside and outside 4 quickly match, the responsiveness of the water tank 2 to a change in water level can be further improved. In addition, the number, position, and shape of the water holes 34 can be appropriately changed.

  FIG. 8 is an overall configuration diagram of a water level measurement system according to the third embodiment of the present invention. The water level measuring system 1A in the present embodiment measures the water level of the water tank 2 stepwise using a plurality of thermocouples with heaters 5a, 5b, 5c.

  The water level measuring system 1A includes protective tubes 4a, 4b, 4c fixed to the inner wall of a water tank 2 opened to the atmosphere via a plurality of support members 3, and heaters housed in the protective tubes 4a, 4b, 4c, respectively. The thermocouple includes a thermocouple 5a, 5b, 5c, and a water level measuring device 6 for measuring a water level based on a thermoelectromotive force signal received from each of the thermocouples with a heater 5a, 5b, 5c. The upper ends of the thermocouples with heaters 5a, 5b, 5c are connected to one ends of cables 8a, 8b, 8c via connectors 7a, 7b, 7c, respectively, and the other ends of the cables 8a, 8b, 8c are connected to a connector 9a. , 9b, 9c to the water level measuring device 6. The configuration of the cables 8a, 8b, 8c is the same as the configuration of the cable 8 in the first embodiment (see FIG. 5). The water level measuring device 6 is connected to a display device 10 for notifying the measurement result and a plurality of lamps 11a, 11b, 11c.

  The upper ends of the thermocouples with heaters 5a, 5b, 5c are fixed to the upper ends of the protection tubes 4a, 4b, 4c via fixing jigs 12a, 12b, 12c, respectively. The lower ends of the thermocouples with heaters 5a, 5b, and 5c include a heater 13 and a thermocouple 14 (see FIG. 2), respectively, and form sensor units 15a, 15b, and 15c. On the upper and lower sides of the sensor portions 15a, 15b, 15c, upper peripheral projections 16a, 16b, 16c and lower peripheral projections 17a, 17b, 17c projecting toward the inner peripheral surfaces of the protection tubes 4a, 4b, 4c. Each is provided. The structure near the sensor portions 15a, 15b, and 15c of the thermocouples with heaters 5a, 5b, and 5c is the same as the structure near the sensor portion 15 in the first embodiment (see FIG. 2).

  The length of the thermocouples with heaters 5a, 5b, 5c is different from the height of the sensor sections 15a, 15b, 15c when the thermocouples with heaters 5a, 5b, 5c are installed in the protective tubes 4a, 4b, 4c. It is set to be placed in. When the thermocouples with heaters 5a, 5b, 5c are installed in the protection tubes 4a, 4b, 4c, the lengths of the protection tubes 4a, 4b, 4c are determined by the sensor portions 15a, 15b, 15c. It is set so as to be disposed near the lower opening in each of 4b and 4c.

  Next, the operation of the water level measuring device 6 in this embodiment will be described with reference to FIG.

  When the water level measurement device 6 is operated, the measurement control circuit 20 selects the sensor unit 15c located at the lowest position among the sensor units 15a, 15b, 15c as a determination target (step S201).

  The water level measuring device 6 performs the same processing as steps S101 to S104 (see FIG. 6) in the first embodiment (steps S202 to S205).

  Upon receiving the ON command from the measurement control circuit 20 in step S205, the heater power supply 18 switches the energization destination to the heater 13 of the sensor unit 15c by a relay provided therein (step S206).

  The water level measurement device 6 performs the same processing as Steps S105 to S111 (see FIG. 6) in the first embodiment (Steps S207 to S213).

  The measurement control circuit 20 turns on or off the lamp 11c corresponding to the sensor unit 15c according to the determination result in step S211 (step S214).

  After the completion of the determination process for the sensor unit 15c, the measurement control circuit 20 selects the sensor unit 15b disposed at the next lower position than the sensor unit 13 as a determination target (Step S201).

  The water level measuring device 6 performs the same processing as steps S101 to S104 (see FIG. 6) in the first embodiment (steps S202 to S205).

  Upon receiving the ON command from the measurement control circuit 20 in step S205, the heater power supply 18 switches the energization destination to the heater 13 of the sensor unit 15b by a relay provided inside (step S206).

  The water level measurement device 6 performs the same processing as Steps S105 to S111 (see FIG. 6) in the first embodiment (Steps S207 to S213).

  The measurement control circuit 20 turns on or off the lamp 11b corresponding to the sensor unit 15b according to the result of the determination in step S211 (step S214).

  After the end of the determination process for the sensor unit 15b, the measurement control circuit 20 selects the sensor unit 15a located at the highest position as a determination target (Step S201).

  The water level measuring device 6 performs the same processing as steps S101 to S104 (see FIG. 6) in the first embodiment (steps S202 to S205).

  Upon receiving the ON command from the measurement control circuit 20 in step S205, the heater power supply 18 switches the energization destination to the heater 13 of the sensor unit 15a by a relay provided therein (step S206).

  The water level measurement device 6 performs the same processing as Steps S105 to S111 (see FIG. 6) in the first embodiment (Steps S207 to S213).

  The measurement control circuit 20 turns on or off the lamp 11a corresponding to the sensor unit 15a according to the determination result of step S211 (step S214).

  After the determination process for the sensor units 15c, 15b, and 15a has been completed (steps S202 to S214) (when YES is determined in step S215), the measurement control circuit 20 determines whether the determination results of the sensor units 15c, 15b, and 15a are correct. The water level information is transmitted to the display device 10 and displayed on the screen 23 (step S216).

  The water level measurement device 6 can monitor the water level of the water tank 2 in a stepwise manner by repeatedly performing the above-described series of processes (steps S201 to S216) at a constant cycle.

  According to the water level measurement system 1A in this embodiment, the upper peripheral projections 16a, 16b, 16c and the lower peripheral projections 17a, 17b, 17c are provided on the upper and lower sides of the sensor sections 15a, 15b, 15c, respectively. Since there is no possibility that the sensor portions 15a, 15b, 15c housed in the protection tubes 4a, 4b, 4c come into contact with the inner walls of the protection tubes 4a, 4b, 4c, the thermoelectric devices with heaters housed in the protection tubes 4a, 4b, 4c. Erroneous detection by pairs 5a, 5b, 5c can be prevented. Further, the upper peripheral projections 16a, 16b, 16c and the lower peripheral projections 17a, 17b, 17c are not fixed to the inner walls of the protective tubes 4a, 4b, 4c, and the upper peripheral projections 16a, 16b, 16c and the lower side. Since the outer diameters of the peripheral projections 17a, 17b, 17c are smaller than the inner diameters of the protection tubes 4a, 4b, 4c, the thermocouples 5a with heaters are kept in a state where the protection tubes 4a, 4b, 4c are fixed inside the water tank 2. 5b and 5c can be easily replaced.

  Furthermore, by arranging the plurality of sensor units 15a, 15b, and 15c at different heights, the water level of the water tank 2 can be measured stepwise. Although FIG. 8 shows a configuration including three thermocouples with heaters 5, the water level measurement is performed by providing more thermocouples with heaters 5 and reducing the height interval of the sensor unit 15. Accuracy can be improved. FIG. 8 shows a configuration in which a plurality of thermocouples with heaters 5a, 5b, and 5c are installed in a plurality of protection tubes 4a, 4b, and 4c, respectively. Thermocouples 5a, 5b, 5c may be provided.

  Note that the present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described above. It is also possible to add a part of the configuration of another embodiment to the configuration of a certain embodiment, delete a part of the configuration of a certain embodiment, or replace it with a part of another embodiment. It is possible.

  1, 1A: water level measurement system, 2: water tank, 3, 3a, 3b, 3c: support member, 4, 4a, 4b, 4c: protective tube, 5, 5a, 5b, 5c: thermocouple with heater, 6: water level Measuring device, 7, 7a, 7b, 7c ... connector, 8, 8a, 8b, 8c ... cable, 9, 9a, 9b, 9c ... connector, 10 ... display device, 11, 11a, 11b, 11c ... lamp, 12, 12a, 12b, 12c: fixing jig, 13: heater, 14: thermocouple, 15, 15a, 15b, 15c: sensor unit, 16, 16A, 16a, 16b, 16c: upper peripheral projection, 17, 17A, 17a, 17b, 17c: lower peripheral projection, 18: heater power supply, 19: voltage measurement circuit, 20: measurement control circuit, 21a, 21b: heater lead wire, 22a: chromel wire (thermocouple wire), 22b: alumel wire (thermoelectric) versus ), 23 ... screen, 24 ... insulating material, 25 ... sheath, 26, 27 ... gap, 28 ... hollow cone, 29 ... cylindrical body, 30 ... welded part, 31a ... chromel wire (compensating lead wire), 31b ... alumel wire (Compensation conductor), 32a, 32b: power supply line, 33: resin material, 34: water passage hole.

Claims (8)

A thermocouple with a heater comprising a heater and a thermocouple was housed in the sheath arranged close to each other, it is fixed to the inside of the atmosphere open water bath, and a protective tube containing a thermocouple one with the heater, In a water level measurement system including a heater power supply for supplying power to the heater and a voltage measurement circuit for measuring an electromotive force of the thermocouple,
An upper peripheral projection having an outer diameter smaller than the inner diameter of the protective tube, provided above the sensor unit in which the heater and the thermocouple are included in the thermocouple with a heater,
Provided on the lower side of the sensor portion, and a lower peripheral projection having an outer diameter smaller than the inner diameter of the protective tube,
A water level measurement system, wherein an outer peripheral surface of the sensor section is exposed to an inner wall of the protection tube . In the water level measurement system according to claim 1,
A water level measurement system, wherein at least one water passage hole is provided in a part of the protection tube covering the sensor unit. In the water level measurement system according to claim 1,
A plurality of thermocouples with a heater having the same configuration as the thermocouple with a heater, and a plurality of protection tubes having the same configuration as the protection tube,
A water level measurement system, wherein the plurality of thermocouples with heaters are housed in each of the plurality of protective tubes such that respective sensor units are arranged at different heights. In the water level measurement system according to claim 1,
Comprising a plurality of heater thermocouples having a configuration equivalent to the heater thermocouple,
A water level measurement system, wherein the plurality of thermocouples with heaters are accommodated in the protective tube such that respective sensor units are arranged at different heights.   A thermocouple with a heater in which a heater and a thermocouple disposed in close proximity to each other are housed in a sheath; a protective tube fixed inside an open water tank and housing the thermocouple with a heater; and the heater In a water level measurement system comprising a heater power supply for supplying power to the power supply and a voltage measurement circuit for measuring the electromotive force of the thermocouple,
  An upper peripheral projection having an outer diameter smaller than the inner diameter of the protection tube, provided above the sensor unit in which the heater and the thermocouple are included in the thermocouple with the heater,
  A lower peripheral projection having an outer diameter smaller than an inner diameter of the protection tube, provided below the sensor unit;
  The water level measurement system according to claim 1, wherein the upper peripheral projection is formed such that a lower surface thereof is inclined downward toward an inner wall of the protection tube.   A thermocouple with a heater in which a heater and a thermocouple disposed in close proximity to each other are housed in a sheath; a protective tube fixed inside an open water tank and housing the thermocouple with a heater; and the heater In a water level measurement system comprising a heater power supply for supplying power to the power supply and a voltage measurement circuit for measuring the electromotive force of the thermocouple,
  An upper peripheral projection having an outer diameter smaller than the inner diameter of the protection tube, provided above the sensor unit in which the heater and the thermocouple are included in the thermocouple with the heater,
  A lower peripheral projection having an outer diameter smaller than an inner diameter of the protection tube, provided below the sensor unit;
  The water level measurement system according to claim 1, wherein the upper peripheral projection is formed so that an upper surface thereof is inclined downward toward an inner wall of the protection tube.   A thermocouple with a heater in which a heater and a thermocouple disposed in close proximity to each other are housed in a sheath; a protective tube fixed inside an open water tank and housing the thermocouple with a heater; and the heater In a water level measurement system comprising a heater power supply for supplying power to the power supply and a voltage measurement circuit for measuring the electromotive force of the thermocouple,
  An upper peripheral projection having an outer diameter smaller than the inner diameter of the protective tube, provided above the sensor unit in which the heater and the thermocouple are included in the thermocouple with a heater,
  A lower peripheral projection having an outer diameter smaller than an inner diameter of the protection tube, provided below the sensor unit;
  The water level measurement system according to claim 1, wherein the lower peripheral protrusion is formed so that an upper surface thereof is inclined downward toward an inner wall of the protection tube.   A thermocouple with a heater in which a heater and a thermocouple arranged in close proximity to each other are housed in a sheath; a protective tube fixed inside an open water tank and housing the thermocouple with a heater; and the heater In a water level measurement system comprising a heater power supply for supplying power to the power supply and a voltage measurement circuit for measuring the electromotive force of the thermocouple,
  An upper peripheral projection having an outer diameter smaller than the inner diameter of the protective tube, provided above the sensor unit in which the heater and the thermocouple are included in the thermocouple with a heater,
  A lower peripheral projection having an outer diameter smaller than an inner diameter of the protection tube, provided below the sensor unit;
  The water level measurement system according to claim 1, wherein the lower peripheral projection is formed such that a lower surface thereof is inclined upward toward an inner wall of the protection tube.

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