JP6427078B2 - Detection device - Google Patents

Description

  The present invention relates to a detection device attached to a tank where liquid is stored and detecting the state of the tank.

  Generally, a tilt sensor is used that measures the tilt angle of the object using changes in capacitance. For example, the tilt sensor disclosed in Patent Document 1 includes an upper electrode, a lower electrode, and a fluid sealed between the upper electrode and the lower electrode and displaced according to the tilt. Then, the inclination angle of the object to be measured is measured by extracting the change of the output signal due to the displacement of the fluid.

  At that time, as the fluid, a substance whose viscosity depends on the frequency of the external force is used. Therefore, it is possible to accurately detect a signal (tilt component) representing a tilt to be measured without requiring a signal processing circuit for removing an unnecessary signal component due to an external force such as acceleration or vibration.

  Further, in the tilt angle sensor disclosed in Patent Document 2, a cylindrical frame made of a conductive material is provided, and both side openings of the frame are covered in a sealed state by an insulating plate. In a frame sealed in a sealed state by an insulating plate, a conductive liquid having a volume that is about half or less than the volume of the conductive liquid in the frame and an insulating liquid having a specific gravity smaller than that of the conductive liquid are enclosed. It is done.

  On the surface of the insulating plate, an arc-shaped external electrode plate in which a semicircular shape or a circular shape is divided into a plurality of pieces so as to obtain capacitance with the conductive liquid is installed. One terminal is connected to the external plate, and the other terminal is connected to the frame. Therefore, there are no mechanical moving parts, wear due to aging, no deviation due to impact, etc., and it can be used for a long time.

JP 10-160458 A Unexamined-Japanese-Patent No. 5-172571

  By the way, there is a case where the inclination of the tank in which the liquid is stored may be detected by using this kind of inclination angle sensor. For example, the installation tank is for detecting the inclination angle of the tank when an earthquake or the like occurs, and the transfer tank is for detecting the inclination angle of the tank during transfer.

  On the other hand, a water level sensor is employed to detect the water level of the liquid stored in the tank. This is to obtain a signal for supplying (replenishing) liquid in the tank. Therefore, there is a problem that usually the inclination sensor for detecting the inclination of the tank and the water level sensor for detecting the water level in the tank are separately provided, which is not economical.

  The present invention solves this kind of problem, and the inclination angle of the tank and the lower limit water level in the tank can be easily and reliably detected by a single sensor, and can be configured economically. It aims to provide a possible detection device.

  The present invention relates to a detector mounted on a tank where liquid is stored and detecting the state of the tank. The detection device includes a sensor support member extending in the vertical direction inside the tank, and a sensor supported by the sensor support member and moved up and down with a change in liquid level. . The sensor support member is provided with a locking portion that restricts movement of the sensor below the lower limit water level.

  The sensor includes a detection unit. The detection units are disposed opposite to each other at the top and bottom, and have upper and lower electrodes that can be in contact with liquid. Then, from the change in capacitance based on the relationship between the amount of liquid and the amount of air between the upper electrode and the lower electrode, it is detected whether the inclination angle of the tank and the water level in the tank are the lower limit water level. ing.

  Further, in this detection device, it is preferable that the upper electrode and the lower electrode each have a flat circular shape. For this reason, the inclination direction of the tank is not limited, and the inclination angle of the tank can be detected uniformly over all angles (360 °).

  Furthermore, in this detection device, it is preferable that the upper electrode and the lower electrode are each formed of a single flat plate. Therefore, it is possible to simplify the overall configuration of the detection device and to easily reduce the manufacturing cost.

  Furthermore, in this detection device, the sensor preferably comprises a cylindrical casing. This allows the sensor to accurately detect the tilt angle of the tank across all angles.

  Further, in this detection device, the sensor preferably includes a detection unit and a buoyancy unit, and the casing unit is preferably formed with an opening through which liquid flows in the detection unit. At that time, the buoyancy part is the whole sensor so that the upper end of the detection part is positioned at the same height as the liquid surface in a state where the tank is not inclined and the sensor is disposed above the locking part. It is preferable to have a buoyancy adjuster that regulates the buoyancy of the

  Therefore, the inclination angle of the tank can be detected with high accuracy by the detection unit, and the inclination angle of various tanks storing various liquids can be detected easily and reliably only by selecting the type of the buoyancy adjuster. It becomes possible.

  Furthermore, in this detection device, the buoyancy adjuster is preferably a gas, liquid or solid filled in the adjustment chamber formed in the casing part. Therefore, the configuration of the buoyant part can be simplified and it is economical.

  Furthermore, the detection device preferably includes a tank state determination unit. When the tank state determination unit detects that the detection unit is filled with the liquid, it determines that the tank exceeds the lower limit water level and stores the liquid and is in the non-inclined state. When the tank state determination unit detects that the detection unit is filled with liquid and air, it determines that the tank exceeds the lower limit water level to store the liquid and is in an inclined state. The tank state determination unit determines that the tank does not store a desired amount of liquid when it detects that the detection unit is filled with air.

  This makes it possible to detect the above three states easily and reliably using a single sensor, which is extremely economical.

  The tank is preferably a reformed water tank provided in a fuel cell system and used in a reformer for steam reforming the fuel gas supplied to the fuel cell system.

  At that time, the detection device operates the fuel cell system when the tank state determination unit determines that the tank is in the inclined state or when the tank does not store the desired amount of liquid. Preferably, a control unit is provided to stop the operation. For this reason, it is possible to prevent exhaustion of the reforming water and to perform stable power generation well.

  Furthermore, in this detection device, the sensor support member is preferably positioned such that the sensor is located at the center of the tank. Therefore, the detection accuracy of the inclination angle of the tank by the sensor can be favorably improved.

  According to the present invention, when the tank inclines, the sensor supported by the sensor support member inclines with respect to the liquid level. Therefore, the capacitance changes based on the relationship between the amount of liquid and the amount of air between the upper electrode and the lower electrode, and the inclination angle of the tank can be detected.

  On the other hand, when the water level is lowered while the sensor is in contact with the locking portion, the amount of liquid between the upper electrode and the lower electrode is reduced, and the capacitance is determined based on the relationship between the amount of liquid and the amount of air. The change makes it possible to detect that the liquid in the tank is at the lower limit.

  As a result, it is possible to easily and reliably detect with a single sensor whether the inclination angle of the tank and the water level in the tank are the lower limit water level, and it is possible to provide an economical detection device. Become.

BRIEF DESCRIPTION OF THE DRAWINGS It is schematic structure explanatory drawing of the fuel cell cogeneration system in which the detection apparatus which concerns on embodiment of this invention is integrated. It is side explanatory drawing of the water tank which comprises the said fuel cell cogeneration system, and the said detection apparatus. It is plane explanatory drawing of the said water tank and the said detection apparatus. It is principal part cross-sectional explanatory drawing of the said detection apparatus. It is an explanatory view when the water tank inclines. It is explanatory drawing at the time of the stored water of the said water tank reducing to the lowest water level line.

  As shown in FIG. 1, a detection device 10 according to an embodiment of the present invention is incorporated into, for example, a fuel cell cogeneration system (fuel cell system) 12. The fuel cell cogeneration system 12 includes a fuel cell module 14, a heat exchanger 16, a water tank 18, a hot water storage tank 20, and a control unit 22.

  The fuel cell module 14 includes a fuel cell stack 24, a steam reformer 26 and an evaporator 28. The fuel cell stack 24 generates electric power by an electrochemical reaction between a fuel gas (a mixture of hydrogen gas and methane and carbon monoxide) and an oxidant gas (air). Although not illustrated, the fuel cell stack 24 includes, for example, a flat solid oxide fuel cell, and a plurality of the fuel cells are stacked in the direction of gravity or in the horizontal direction.

  The fuel cell includes, for example, an electrolyte electrode assembly (MEA) in which a cathode electrode and an anode electrode are provided on both sides of an electrolyte composed of an oxide ion conductor such as stabilized zirconia. A cathode separator and an anode separator are disposed on both sides of the electrolyte electrode assembly. In the cathode separator, an oxidant gas channel for supplying oxidant gas to the cathode electrode is formed, and in the anode separator, a fuel gas channel for supplying fuel gas to the anode electrode is formed.

  The steam reformer 26 steam-reforms a mixed gas of a raw fuel mainly composed of hydrocarbons (for example, city gas) and steam to generate a fuel gas, and supplies the fuel gas to the fuel cell stack 24. . The evaporator 28 evaporates the reforming water and supplies steam to the steam reformer 26.

  The heat exchanger 16 is supplied with the exhaust gas (spent fuel gas and oxidant gas) discharged from the fuel cell module 14 through the exhaust gas flow path 30 and the hot water storage tank 20 through the water discharge flow path 32. The heat exchange water is heated by heat exchange with the heat exchange water.

  Condensed water generated from the exhaust gas by the heat exchange of the heat exchanger 16 flows through the water flow path 34 and is stored in the water tank 18. The water tank 18 supplies the stored condensed water to the evaporator 28 from the water supply passage 36 as reforming water. The heat exchanger 16 supplies hot water (hot water), which is heat exchange water heated by heat exchange, to the hot water storage tank 20 via the hot water supply flow path 38.

  The hot water storage tank 20 is provided with a hot water discharge flow path 40 for discharging the hot water to the outside. The hot water discharge flow path 40 supplies hot water to a hot water supply system and a heating system in a home (not shown). The raw fuel is supplied to the fuel cell module 14 through the raw fuel supply channel 42, and the air is supplied through the air supply channel 43.

  As shown in FIGS. 2 and 3, the water tank 18 has a square shape in plan view. The water tank 18 may have a rectangular shape or a circular shape in a plan view. Water (liquid) is stored in the water tank 18, and the detection device 10 detects the state of the water tank 18. A sensor support member 44 is provided in the water tank 18 so as to extend in the vertical direction. The sensor support member 44 is, for example, a square rod-like support, and the sensor support member 44 supports the sensor 46 so as to be able to move up and down.

  As shown in FIGS. 2 to 4, the sensor 46 includes a cylindrical resin casing 48. The upper and lower ends of the casing portion 48 are closed, and as shown in FIG. 2, the diameter D is set larger than the height H (diameter D> height H). The diameter D may be equal to the height H, or the diameter D may be less than the height H.

  A guide portion 50 is integrally provided on the side surface of the casing portion 48, and a sensor support member 44 is inserted into a rectangular hole 50a formed in the guide portion 50 in the vertical direction (see FIG. 4). As shown in FIG. 3, the sensor support member 44 is positioned such that the center O of the sensor 46 is located at the center of the water tank 18. The center O is separated from each side of the water tank 18 by a distance S1. The sensor support member 44 has a rectangular cross section to prevent the sensor 46 from swinging (rotating). The sensor support member 44 may have an anti-rotation function, and can be set in various shapes such as a square cross section, a rectangular cross section, or a semicircular cross section.

  As shown in FIG. 2, the sensor support member 44 is provided with a locking portion 44 s that restricts movement of the sensor 46 below the lowest water level line (lower limit water level) WL (low). The locking portion 44s is a large diameter portion integrally formed with the sensor support member 44, and holds the lower end position of the sensor 46 at the lowest water level line WL (low) of the water tank 18.

  The sensor 46 includes a detection unit 52 and a buoyancy unit 54, as shown in FIG. The detection unit 52 is disposed to be opposed to each other, and has an upper electrode 56 u and a lower electrode 56 d that can be in contact with liquid. One end of an electric wire 58a, 58b is connected to the upper electrode 56u and the lower electrode 56d, and the other end of the electric wire 58a, 58b is connected to the connector 60 (see FIG. 2). The connector 60 is attached to the top of the water tank 18 and connected to the control unit 22. The upper electrode 56 u and the lower electrode 56 d can also send signals to the control unit 22 wirelessly.

  As shown in FIG. 1, the control unit 22 determines the inclination angle of the water tank 18 based on the change in capacitance based on the relationship between the amount of water (the amount of liquid) and the amount of air between the upper electrode 56 u and the lower electrode 56 d. And it is detected whether the water level in the water tank 18 is the lowest water level line WL (low) (described later).

  As shown in FIG. 4, the upper electrode 56 u and the lower electrode 56 d each have a flat circular shape. Preferably, the upper electrode 56 u and the lower electrode 56 d are each formed of a single flat plate (disk). The casing portion 48 is formed with a plurality of openings 62 for circulating water in the detection portion 52. The opening 62 has a rectangular shape, and is annularly disposed between the upper electrode 56 u and the lower electrode 56 d.

  The buoyancy portion 54 has a buoyancy adjuster 64. The buoyancy adjuster 64 has the same height as the water level line (liquid level) WL at the upper end of the detection unit 52 in a state where the water tank 18 is not inclined and the sensor 46 is disposed above the locking portion 44s. The buoyancy of the entire sensor 46 is adjusted to be located at The buoyancy adjusting body 64 is a fluid, for example, air (gas) filled in the adjusting chamber 66 formed in the casing portion 48. Note that depending on the type of liquid in which the sensor 46 is immersed, the adjustment chamber 66 can be filled with a buoyancy adjuster 64 that is a liquid or a solid. This is to cope with specific gravity other than water.

  As shown in FIG. 1, the detection device 10 includes a tank state determination unit 68. The tank state determination unit 68 may be configured as a function of the control unit 22 or may be configured separately from the control unit 22. When the tank state determination unit 68 detects that the detection unit 52 is filled with water, it determines that the water tank 18 stores the water beyond the lowest water level line WL (low) and is in the non-inclined state Do.

  When the tank state determination unit 68 detects that the detection unit 52 is filled with water and air, the water tank 18 stores the water beyond the lowest water level line WL (low) and is in the inclined state to decide. When the tank state determination unit 68 detects that the detection unit 52 is filled with air, it determines that the water tank 18 does not store the desired amount of water.

  When the control unit 22 determines that the water tank 18 is in the inclined state by the tank state determination unit 68 or when the water tank 18 does not store a desired amount of water, The operation of the generation system 12 is stopped.

  The operation of the fuel cell cogeneration system 12 incorporating the detection device 10 configured as described above will be described below.

At the time of operation of the fuel cell cogeneration system 12, raw fuel such as city gas (including CH ₄ , C ₂ H ₆ , C ₃ H ₈ , C ₄ H ₁₀ ) is supplied to the raw fuel supply flow path 42, for example. Ru. The raw fuel is supplied to the fuel cell module 14, and the reforming water is supplied from the water tank 18 to the evaporator 28 through the water supply passage 36 to obtain steam.

Therefore, the steam reformer 26 steam-reforms the mixed fuel of the raw fuel and the steam, removes (reforms) the C ₂₊ hydrocarbons, and produces a reformed gas containing mainly methane (fuel gas (fuel gas) ) Is obtained. The reformed gas is supplied to the fuel cell stack 24. Accordingly, methane in the reformed gas is reformed to obtain hydrogen gas, and the fuel gas containing hydrogen as a main component is supplied to the anode electrode (not shown).

  On the other hand, air is supplied to the fuel cell module 14 via the air supply flow path 43. Air is introduced into the fuel cell stack 24 after being warmed as required, and supplied to a cathode electrode (not shown). Thereby, power generation is performed by the electrochemical reaction of the fuel gas and air.

  The high temperature (several hundred degrees Celsius) exhaust gas discharged from the fuel cell module 14 through the exhaust gas flow path 30 is sent to the heat exchanger 16. Heat exchange water is supplied to the heat exchanger 16 from the hot water storage tank 20 via the water discharge flow path 32. For this reason, in the heat exchanger 16, the high temperature exhaust gas and the heat exchange water exchange heat, and the heat exchange water is heated to obtain hot water. The hot water is supplied to the hot water storage tank 20 via the hot water supply flow path 38. In the hot water storage tank 20, hot water is supplied to a hot water supply system and a heating system in a home (not shown) through the hot water discharge flow path 40.

  On the other hand, condensed water is generated from the exhaust gas by heat exchange in the heat exchanger 16. The condensed water flows through the water flow passage 34 and is stored in the water tank 18, and is also supplied from the water supply passage 36 to the evaporator 28 as reforming water.

  In this case, in the present embodiment, as shown in FIG. 2, the detection device 10 is supported by a sensor support member 44 provided extending in the vertical direction inside the water tank 18, and the sensor support member 44, And a sensor 46 which ascends and descends with the change of the water level line WL. The sensor 46 is provided with a detection unit 52 which is disposed to face each other at the top and bottom and has an upper electrode 56u and a lower electrode 56d which can be in contact with liquid (see FIG. 4).

  Then, the control unit 22 determines the inclination angle of the water tank 18 and the water tank 18 from the change in capacitance based on the relationship between the amount of water (amount of liquid) and the amount of air between the upper electrode 56 u and the lower electrode 56 d. It is detected whether the water level inside is the lowest water level line WL (low). Specifically, an upper electrode 56u and a lower electrode 56d each having an area A are arranged to be separated by a distance L, and a dielectric constant is provided between the upper electrode 56u and the lower electrode 56d. There is a dielectric of ε.

  Therefore, the capacitance C between the upper electrode 56 u and the lower electrode 56 d is obtained from C = ε (A / L). Here, the dielectric may be water only (first state), water and air mixed (second state), and air only (third state). While the relative permittivity of water is 80.4, the relative permittivity of air is 1.0, and the capacitance C1 in the first state, the capacitance C2 in the second state, and the third state The capacitance C3 at this time is C1> C2> C3.

  As shown in FIG. 2, the water in the water level line WL above the lowest water level line WL (low) is stored in the water tank 18, and when the water tank 18 is not inclined, the detection unit 52 is full of water. It is done. For this reason, in the sensor 46, a capacitance C1 is obtained, and the tank state determination unit 68 detects that the detection unit 52 is filled with water.

  On the other hand, as shown in FIG. 5, when the water tank 18 is inclined due to an external impact such as an earthquake, for example, the detection unit 52 is filled with water and air. Therefore, in the sensor 46, the capacitance C2 is obtained, and the tank state determination unit 68 detects that the water tank 18 stores water beyond the lowest water level line WL (low) and is in the inclined state. The control unit 22 stops the operation of the fuel cell cogeneration system 12 when determining that the water tank 18 is inclined at a predetermined angle or more.

  In addition, when the stored water in the water tank 18 decreases, the water level line WL is lowered, and the sensor 46 is lowered along the water level line WL. Then, the sensor 46 abuts on the locking portion 44 s of the sensor support member 44 and the descent is suppressed. Therefore, even if the water level line WL descends, the sensor 46 does not descend. As a result, the detection unit 52 changes from being filled with water to being filled with water and air, and then becomes filled with only air.

  For this reason, as shown in FIG. 6, the liquid level drops to the lowest water level line WL (low), the electrostatic capacitance C3 is obtained by the sensor 46, and the tank state determination unit 68 determines that the water tank 18 has a desired amount. To detect that no liquid is stored. If the controller 22 determines that the water tank 18 does not store the desired amount of liquid, the controller 22 stops the operation of the fuel cell cogeneration system 12.

  Thus, in the present embodiment, when the water tank 18 is inclined, the sensor 46 supported by the sensor support member 44 is inclined with respect to the water surface (liquid surface) in the water tank 18. Therefore, the capacitance C based on the relationship between the amount of water and the amount of air between the upper electrode 56 u and the lower electrode 56 d changes to the capacitance C 2, and the inclination angle of the water tank 18 can be detected.

  On the other hand, when the water level line WL is lowered with the sensor 46 in contact with the locking portion 44s, the amount of liquid between the upper electrode 56u and the lower electrode 56d is reduced. As a result, the capacitance C based on the relationship between the amount of water and the amount of air changes to the capacitance C3, so that it is possible to detect that the water level in the water tank 18 is the lowest water level line WL (low). become.

  Therefore, the single sensor 46 can easily and reliably detect the inclination angle of the water tank 18 and whether the water level in the water tank 18 is the lowest water level line WL (low), which is economical. The effect is obtained that it is possible to provide a simple detection device 10.

  Further, in the detection device 10, the upper electrode 56u and the lower electrode 56d each have a flat plate circular shape. Accordingly, the inclination direction of the water tank 18 is not limited, and the inclination angle can be detected uniformly over all angles (360 °). Moreover, by adjusting the distance L between the upper electrode 56u and the lower electrode 56d (inter-electrode distance) L and the diameter (electrode area) of the upper electrode 56u and the lower electrode 56d, the accuracy of the tilt angle of the water tank 18 Can be changed.

  Furthermore, in the detection device 10, the upper electrode 56u and the lower electrode 56d are each formed of a single flat plate. As a result, the entire configuration of the detection device 10 can be simplified, and reduction in manufacturing cost can be easily achieved.

  Furthermore, the sensor 46 comprises a cylindrical casing 48. Thus, the sensor 46 can accurately detect the tilt angle of the water tank 18 over all angles.

  Further, the sensor 46 includes a detection unit 52 and a buoyancy unit 54, and the casing unit 48 is formed with a plurality of openings 62 for circulating water in the detection unit 52. The opening 62 has a rectangular shape, and is annularly disposed between the upper electrode 56 u and the lower electrode 56 d. Therefore, water can be reliably circulated in the detection unit 52, and the inclination angle of the casing unit 48 can be detected with high accuracy over all angles.

  At that time, the buoyant portion 54 has a buoyancy adjuster (air) 64 that adjusts the buoyancy of the entire sensor 46. In the buoyancy adjuster 64, the upper end of the detection unit 52 is positioned at the same height as the water level line WL in a state where the water tank 18 is not inclined and the sensor 46 is disposed above the locking unit 44s. To adjust. Thereby, the inclination angle of the water tank 18 can be detected with high accuracy by the detection unit 52, and the inclination angles of various tanks storing various liquids can be easily and simply by selecting the kind of the buoyancy adjuster 64. It becomes possible to detect reliably.

  Furthermore, the buoyancy adjustment body 64 is a fluid, for example, air, which is filled in the adjustment chamber 66 formed in the casing portion 48. Therefore, the configuration of the buoyant portion 54 can be simplified, and it has an advantage of being economical.

  Furthermore, the detection device 10 includes a tank state determination unit 68. The tank state determination unit 68 stores the water above the lowest water level line WL (low) and stores the water, and the water tank 18 is non-inclined. The water tank 18 exceeds the lowest water level line WL (low) Are stored, and it is determined that the water tank 18 is not storing a desired amount of water. Therefore, using the single sensor 46, the above three states can be detected easily and reliably, which is extremely economical.

  The water tank 18 is a reforming water tank provided in the fuel cell cogeneration system 12 and used in a steam reformer 26 for steam reforming the fuel gas supplied to the fuel cell stack 24. At that time, when the control unit 22 determines that the water tank 18 is in the inclined state or determines that the water tank 18 does not store a desired amount of water, the control unit 22 of the fuel cell cogeneration system 12 It has stopped working. This makes it possible to prevent exhaustion of the reforming water and to perform stable power generation well.

  Furthermore, the sensor support member 44 is positioned in the water tank 18 so that the center O of the sensor 46 is located at the center of the water tank 18, as shown in FIG. Therefore, the detection accuracy of the tilt angle of the water tank 18 by the sensor 46 can be favorably improved.

12 Fuel Cell Cogeneration System 14 Fuel Cell Module 16 Heat Exchanger 18 Water Tank 20 Storage Tank 22 Control Unit 24 Fuel Cell Stack 26 Steam Reformer 28 Evaporator 44 Sensor Support Member 44s ... Locking part 46 ... Sensor 48 ... Casing part 50 ... Guide part 52 ... Detection part 54 ... Buoyancy part 56 d ... Lower electrode 56 u ... Upper electrode 60 ... Connector 62 ... Opening 64 ... Buoyancy adjuster 66 ... Adjustment chamber 68 ... Tank condition judgment unit

Claims (9)

A detection device mounted on a tank for storing liquid and detecting a state of the tank,
A sensor support member provided vertically extending inside the tank;
A sensor that is supported by the sensor support member and that moves up and down with changes in the water level of the liquid;
A locking portion provided on the sensor support member for restricting movement of the sensor below the lower limit water level;
Equipped with
The sensor has an upper electrode and a lower electrode which are disposed to be opposed to each other at the top and the bottom and the liquid can come into contact, and the relationship between the amount of liquid and the amount of air between the upper electrode and the lower electrode A detection device comprising: a detection unit configured to detect whether an inclination angle of the tank and a water level in the tank are the lower limit water level from a change in capacitance based on the detection result.   The detection device according to claim 1, wherein the upper electrode and the lower electrode each have a flat plate circular shape.   The detection device according to claim 2, wherein the upper electrode and the lower electrode are each formed of a single flat plate.   The detection device according to claim 2, wherein the sensor comprises a cylindrical casing portion. The detection device according to claim 4, wherein the sensor includes the detection unit and a buoyancy unit.
The casing portion is formed with an opening through which the liquid flows in the detection portion,
The buoyant portion is configured such that the upper end of the detection portion is positioned at the same height as the liquid surface in a state where the tank is not inclined and the sensor is disposed above the locking portion. A detection device characterized by comprising a buoyancy adjuster for adjusting the buoyancy of the entire sensor.   The detection device according to claim 5, wherein the buoyancy adjustment body is a gas, liquid or solid filled in an adjustment chamber formed in the casing portion.   The detection device according to claim 5 or 6, wherein when the detection unit detects that the liquid is filled, it is determined that the tank stores the liquid over the lower limit water level and is not inclined. When the detection unit detects that the liquid and air are filled, it is determined that the tank exceeds the lower limit water level to store the liquid and is in an inclined state, and the detection unit further detects the liquid. A detection device characterized by comprising a tank state judgment unit which judges that the tank does not store a desired amount of the liquid when it is detected that the tank is full of air. 8. The detection device according to claim 7, wherein the tank is a reforming water tank provided in a fuel cell system and used in a reformer for steam reforming fuel gas supplied to the fuel cell system,
In the fuel cell system, when the detection device determines that the tank is inclined or the tank does not store a desired amount of the liquid by the tank state determination unit. A detection device comprising a control unit for stopping operation.   The sensing device according to any one of the preceding claims, wherein the sensor support member is positioned such that the sensor is located at the center of the tank.

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