Electromagnetic flowmeter

Abstract

To determine, with a simple structure, an internal state of a pipe such as a state of not being full of water.SOLUTION: An electromagnetic flowmeter 10 for measuring a flow rate of a fluid 14 flowing through a pipe 11, comprises: a first ultrasonic sensor 18A configured to transmit an ultrasonic wave to an inside of the pipe 11 along a direction of gravity and receive an ultrasonic wave traveling in a direction opposite to a direction of gravity; a second ultrasonic sensor 18B separated from the first ultrasonic sensor 18A in the direction of gravity, disposed opposite to the first ultrasonic sensor 18A, and configured to transmit an ultrasonic wave to the inside of the pipe 11 along a direction opposite to the direction of gravity and receive an ultrasonic wave traveling in the direction of gravity; and an arithmetic unit 17 configured to determine a state of the inside of the pipe 11, based on respective ultrasonic reception waveforms of the first ultrasonic sensor 18A and the second ultrasonic sensor 18B.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a magnetic flow meter. [Background technology]

[0002] Patent Documents 1 to 3 disclose electromagnetic flow meters. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 61-140918 [Patent Document 2] Japanese Utility Model Application Publication No. 03-017519 [Patent Document 3] JP 2006-023181 A Summary of the Invention [Problem to be solved by the invention]

[0004] The electromagnetic flowmeters disclosed in Patent Documents 1 and 2 cannot measure flow rates in a non-full state. The flowmeter disclosed in Patent Document 3 combines a conventional flume structure with an electromagnetic flowmeter, resulting in a complex structure and high costs.

[0005] An object of the present disclosure is to determine the internal condition of a pipe, such as a non-full water state, using a simple structure. [Means for solving the problem]

[0006] A magnetic flowmeter according to several embodiments is described below.

[0007] [1] An electromagnetic flowmeter for measuring a flow rate of a fluid flowing through a pipe, A first ultrasonic sensor that transmits ultrasonic waves along the gravity direction to the inside of the pipe and receives ultrasonic waves traveling in an antigravity direction; A second ultrasonic sensor that is spaced apart from the first ultrasonic sensor in the gravity direction and faces the first ultrasonic sensor, transmits ultrasonic waves along an antigravity direction to the inside of the pipe, and receives ultrasonic waves traveling in the gravity direction; a calculator that determines an internal state of the piping based on ultrasonic reception waveforms of the first ultrasonic sensor and the second ultrasonic sensor; An electromagnetic flow meter comprising:

[0008] Such an electromagnetic flowmeter has a simple structure and can determine the internal condition of a pipe.

[0009] [2] The electromagnetic flowmeter according to [1], wherein the computing unit determines whether the inside of the pipe is filled with the fluid as the internal state of the pipe.

[0010] Such an electromagnetic flowmeter has a simple structure and can determine whether the inside of a pipe is filled with fluid.

[0011] [3] The electromagnetic flowmeter according to [2], wherein the computing unit outputs an alarm when it determines that the inside of the pipe is not filled with the fluid.

[0012] Such an electromagnetic flow meter can notify the user when the inside of the pipe is not filled with fluid.

[0013] [4] The electromagnetic flowmeter according to [2] or [3], wherein the calculator determines that the inside of the pipe is filled with the fluid when the ultrasonic reception waveform of the first ultrasonic sensor includes the reception waveform of the ultrasonic wave transmitted from the second ultrasonic sensor and when the ultrasonic reception waveform of the second ultrasonic sensor includes the reception waveform of the ultrasonic wave transmitted from the first ultrasonic sensor.

[0014] Such an electromagnetic flow meter can accurately detect whether the inside of the pipe is filled with fluid.

[0015] [5] The electromagnetic flowmeter according to any one of [2] to [4], wherein the computing unit detects a time difference between received waveforms of reflected waves generated when the ultrasonic waves transmitted from the second ultrasonic sensor enter the fluid and are reflected at the interface, the received waveforms being included in the ultrasonic received waveforms of the second ultrasonic sensor at multiple points in time, thereby detecting a non-full state in which the inside of the pipe is not filled with the fluid.

[0016] In such an electromagnetic flow meter, it is possible to accurately detect a state in which the inside of the pipe is not filled with fluid.

[0017] [6] The electromagnetic flowmeter according to [5], wherein when the computing unit detects the non-full state, the computing unit calculates the level of the fluid from the time difference between the transmission of the ultrasonic wave from the second ultrasonic sensor and the reception of the reflected wave, and reflects the calculation result of the fluid level in the measurement result of the flow rate of the fluid.

[0018] In such an electromagnetic flowmeter, the flow rate of a fluid can be measured with high accuracy even when the inside of the pipe is not filled with the fluid.

[0019] [7] The electromagnetic flowmeter according to any one of [1] to [6], wherein the computing unit determines whether or not sediment has accumulated at the bottom of the pipe as the internal condition of the pipe.

[0020] Such an electromagnetic flowmeter has a simple structure and can determine whether deposits have accumulated at the bottom of a pipe.

[0021] [8] The electromagnetic flowmeter according to [7], wherein the computing unit outputs an alarm when it determines that the deposits have accumulated at the bottom of the pipe.

[0022] Such an electromagnetic flow meter can notify the user of the presence of deposits at the bottom of the pipe.

[0023] [9] The electromagnetic flowmeter according to [7] or [8], wherein the computing unit detects a time difference between received waveforms of reflected waves generated when ultrasonic waves transmitted from the first ultrasonic sensor enter the fluid and are reflected at an interface between the fluid and the received waveforms of the first ultrasonic sensor at multiple points in time, thereby detecting a state in which the sediments have accumulated at the bottom of the pipe.

[0024] Such an electromagnetic flow meter can accurately detect the accumulation of deposits at the bottom of a pipe.

[0025]

[10] The electromagnetic flowmeter described in [9], wherein when the calculator detects the accumulation state, it calculates the height of the deposit from the time difference between the transmission of the ultrasonic wave from the first ultrasonic sensor and the reception of the reflected wave, and reflects the calculation result of the height of the deposit in the measurement result of the flow rate of the fluid.

[0026] In such an electromagnetic flowmeter, the flow rate of a fluid can be measured with high accuracy even when sediment has accumulated at the bottom of the pipe.

[0027]

[11] The electromagnetic flowmeter according to any one of [1] to

[10] , wherein the computing unit determines whether a non-full state in which the inside of the pipe is not filled with the fluid and a full state in which sediments have accumulated at the bottom of the pipe are occurring simultaneously by comparing the ultrasonic reception waveform of the first ultrasonic sensor at a first point in time with the ultrasonic reception waveform of the first ultrasonic sensor at a second point in time when the inside of the pipe is filled with the fluid, and by comparing the ultrasonic reception waveform of the second ultrasonic sensor at the first point in time with the ultrasonic reception waveform of the second ultrasonic sensor at the second point in time.

[0028] Such an electromagnetic flowmeter has a simple structure and can determine whether the inside of the pipe is not filled with fluid and whether deposits have accumulated at the bottom of the pipe at the same time.

[0029]

[12] The electromagnetic flowmeter according to any one of [1] to

[11] , wherein the calculator detects a time difference between received waveforms of reflected waves generated when ultrasonic waves transmitted from the first ultrasonic sensor or the second ultrasonic sensor enter a lining applied to an inner surface of the pipe and are reflected at an interface between the lining and the fluid, the received waveforms being included in ultrasonic received waveforms of the first ultrasonic sensor or the second ultrasonic sensor at multiple points in time, thereby detecting a change in the thickness of the lining.

[0030] Such an electromagnetic flowmeter has a simple structure and is capable of detecting changes in the thickness of the lining.

[0031]

[13] The electromagnetic flowmeter according to

[12] , wherein the calculator outputs an alarm when it determines that the thickness of the lining is equal to or less than a threshold value.

[0032] In such an electromagnetic flowmeter, the user can be notified of deterioration of the lining.

[0033]

[14] The electromagnetic flowmeter according to any one of [1] to

[13] , further comprising an earth ring to which the first ultrasonic sensor and the second ultrasonic sensor are attached.

[0034] In such an electromagnetic flowmeter, an ultrasonic sensor can be installed as a retrofit.

[0035]

[15] The electromagnetic flowmeter according to any one of [1] to

[13] , wherein the first ultrasonic sensor and the second ultrasonic sensor are attached to an outer peripheral surface of the pipe.

[0036] In such an electromagnetic flowmeter, the ultrasonic sensor can be easily installed.

[0037]

[16] The electromagnetic flowmeter according to any one of [1] to

[13] , wherein the first ultrasonic sensor and the second ultrasonic sensor are attached to the outer peripheral surface of a lining applied to the inner peripheral surface of the pipe and penetrate the pipe.

[0038] In such an electromagnetic flowmeter, it is not necessary to bring the ultrasonic sensor into contact with the fluid, and it is possible to reduce the number of interfaces at which the ultrasonic waves transmitted from the ultrasonic sensor are reflected.

[0039]

[17] The electromagnetic flowmeter according to any one of [1] to

[13] , wherein the first ultrasonic sensor and the second ultrasonic sensor are attached to the pipe and penetrate the pipe and a lining applied to an inner surface of the pipe.

[0040] In such an electromagnetic flowmeter, the number of interfaces at which the ultrasonic waves transmitted from the ultrasonic sensor are reflected can be reduced.

[0041]

[18] The electromagnetic flowmeter according to any one of [1] to

[17] , further comprising a pair of electrodes attached to the pipe, covering a portion of an inner surface of a lining applied to the inner surface of the pipe, and extending to a position where the electrodes come into contact with the fluid even when less than 50% of the inside of the pipe is filled with the fluid.

[0042] In such an electromagnetic flowmeter, the flow rate of a fluid can be measured even when the fluid level is low. Effect of the Invention

[0043] According to the present disclosure, it is possible to determine the internal condition of a pipe, such as a non-full water state, with a simple structure. [Brief description of the drawings]

[0044] [Figure 1] FIG. 1 is a diagram illustrating a configuration of an electromagnetic flowmeter according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 is a partial perspective view of an electromagnetic flowmeter according to an embodiment of the present disclosure. [Diagram 3] FIG. 13 is a partial perspective view of a modified example of an electromagnetic flowmeter according to an embodiment of the present disclosure. [Figure 4] FIG. 2 is a diagram illustrating an arrangement of ultrasonic sensors according to an embodiment of the present disclosure. [Diagram 5] FIG. 13 is a diagram illustrating a modified example of an arrangement of ultrasonic sensors according to an embodiment of the present disclosure. [Figure 6] FIG. 13 is a diagram illustrating another modified example of the arrangement of ultrasonic sensors according to an embodiment of the present disclosure. [Figure 7] 1A to 1C are diagrams illustrating an example of ultrasonic transmission and reception in a full water state by an ultrasonic sensor according to an embodiment of the present disclosure. [Figure 8] FIG. 8 is a diagram showing an example of transmitted and received waveforms corresponding to FIG. 7. [Figure 9] 1A to 1C are diagrams illustrating an example of ultrasonic transmission and reception in a non-full water state by an ultrasonic sensor according to an embodiment of the present disclosure. [Figure 10] FIG. 10 is a diagram showing an example of transmission and reception waveforms corresponding to FIG. 9. [Figure 11] 1A to 1C are diagrams illustrating an example of ultrasonic transmission and reception by an ultrasonic sensor according to an embodiment of the present disclosure in a state where deposits have accumulated at the bottom of a pipe. [Figure 12] 12 is a diagram showing an example of transmission and reception waveforms corresponding to FIG. 11. [Figure 13] 1A to 1C are diagrams illustrating an example of ultrasonic transmission and reception by an ultrasonic sensor according to an embodiment of the present disclosure in a non-full water state and in a state in which sediments have accumulated at the bottom of a pipe. [Figure 14] FIG. 14 is a diagram showing an example of transmitted and received waveforms corresponding to FIG. 13. [Figure 15] 4 is a flowchart illustrating an operation of an electromagnetic flowmeter according to an embodiment of the present disclosure. [Figure 16] FIG. 13 is a diagram illustrating a modified example of the configuration of an electromagnetic flowmeter according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

[0046] In each drawing, the same or corresponding parts are denoted by the same reference numerals. In the description of each embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate.

[0047] The configuration of an electromagnetic flowmeter 10 according to this embodiment will be described with reference to Fig. 1. Fig. 1 shows a cross section of a pipe 11 to which the electromagnetic flowmeter 10 is attached, and each of the components of the electromagnetic flowmeter 10.

[0048] The electromagnetic flowmeter 10 is a device that measures the flow rate of a fluid 14 flowing through a pipe 11. The fluid 14 is a conductive liquid such as tap water. The pipe 11 is made of a metal such as stainless steel. The inside of the pipe 11 is covered with an insulator called a lining 12. That is, the lining 12 is applied to the inner peripheral surface of the pipe 11.

[0049] The electromagnetic flowmeter 10 includes a pair of excitation coils including a first excitation coil 13A and a second excitation coil 13B, a pair of electrodes including a first electrode 15A and a second electrode 15B, an amplifier 16, a calculator 17, a pair of ultrasonic sensors including a first ultrasonic sensor 18A and a second ultrasonic sensor 18B, a switch 20, a transmission / reception circuit 21, and a display 24.

[0050] The first excitation coil 13A and the second excitation coil 13B are arranged at the top and bottom of the pipe 11 so as to be aligned in a direction perpendicular to the pipe axis. The first excitation coil 13A and the second excitation coil 13B generate a magnetic field inside the pipe 11. The first electrode 15A and the second electrode 15B are arranged at the left and right sides of the pipe 11 so as to be aligned in a direction perpendicular to the pipe axis and perpendicular to the direction in which the first excitation coil 13A and the second excitation coil 13B are aligned. According to Faraday's law of electromagnetic induction, when a flow velocity occurs in the conductive fluid 14 inside the pipe 11, an electromotive force is generated in a direction perpendicular to the magnetic field generated by the first excitation coil 13A and the second excitation coil 13B and perpendicular to the pipe axis. The generated electromotive force is picked up by the first electrode 15A and the second electrode 15B, and a voltage corresponding to the flow rate induced between the first electrode 15A and the second electrode 15B is amplified by the amplifier 16 and taken into the calculator 17. The first excitation coil 13A and the second excitation coil 13B are driven by an excitation current from an excitation circuit, but since this is a known configuration, a description thereof will be omitted.

[0051] The first ultrasonic sensor 18A and the second ultrasonic sensor 18B are arranged at the top and bottom of the pipe 11, respectively, in a direction perpendicular to the pipe axis and perpendicular to the direction in which the first electrode 15A and the second electrode 15B are arranged, that is, in the same direction as the direction in which the first excitation coil 13A and the second excitation coil 13B are arranged. The first ultrasonic sensor 18A and the second ultrasonic sensor 18B are connected to a transmission / reception circuit 21 via a switch 20. The transmission / reception circuit 21 is connected to a calculator 17. The calculator 17 is, for example, a computer such as a microcomputer. The calculator 17 controls the timing of transmission and reception of various sensor signals and calculates flow rates. The calculator 17 is connected to a display 24. The display 24 is, for example, an LCD or an organic EL display. "LCD" is an abbreviation for liquid crystal display. "EL" is an abbreviation for electro luminescent. The display 24 displays the results of the flow rate calculation and various alarms. The calculator 17 may be connected to a speaker instead of or in addition to the display 24. The speaker may output the flow rate calculation results and various alarms by voice.

[0052] The present embodiment will be outlined with reference to FIG.

[0053] The first ultrasonic sensor 18A transmits ultrasonic waves along the gravity direction to the inside of the pipe 11 and receives ultrasonic waves traveling in the antigravity direction. The second ultrasonic sensor 18B faces the first ultrasonic sensor 18A, separated from the first ultrasonic sensor 18A in the gravity direction. The second ultrasonic sensor 18B transmits ultrasonic waves along the antigravity direction to the inside of the pipe 11 and receives ultrasonic waves traveling in the gravity direction. The calculator 17 determines the state inside the pipe 11 based on the ultrasonic reception waveforms of the first ultrasonic sensor 18A and the second ultrasonic sensor 18B. Therefore, according to this embodiment, the state inside the pipe 11 can be determined with a simple structure.

[0054] In this embodiment, the calculator 17 determines whether the inside of the pipe 11 is filled with the fluid 14 as the internal state of the pipe 11. The calculator 17 has a function of correcting the result of the flow rate calculation depending on the result of this determination. Therefore, according to this embodiment, not only can it be determined with a simple structure whether the inside of the pipe 11 is filled with the fluid 14, but also the flow rate of the fluid 14 can be measured with high accuracy even when the inside of the pipe 11 is not filled with the fluid 14.

[0055] In this embodiment, the calculator 17 further determines whether or not deposits 23 as shown in Fig. 11 have accumulated at the bottom of the pipe 11 as the internal state of the pipe 11. The calculator 17 also has a function of correcting the result of the flow rate calculation depending on the result of this determination. Therefore, according to this embodiment, not only can it be determined with a simple structure whether deposits 23 have accumulated at the bottom of the pipe 11, but the flow rate of the fluid 14 can also be measured with high accuracy even in a state in which deposits 23 have accumulated at the bottom of the pipe 11.

[0056] The arrangement of ultrasonic sensors according to this embodiment will be described with reference to FIG.

[0057] The first ultrasonic sensor 18A and the second ultrasonic sensor 18B are preferably installed at positions that avoid the first excitation coil 13A and the second excitation coil 13B, respectively. For example, as shown in Fig. 2, the first ultrasonic sensor 18A and the second ultrasonic sensor 18B are preferably installed downstream of the first excitation coil 13A and the second excitation coil 13B.

[0058] In this embodiment, the electromagnetic flowmeter 10 further includes an earth ring 19. The earth ring 19 is an accessory for electrically earthing the electromagnetic flowmeter 10.

[0059] A modified example of the arrangement of ultrasonic sensors according to this embodiment will be described with reference to FIG.

[0060] The first ultrasonic sensor 18A and the second ultrasonic sensor 18B may be attached to the earth ring 19. According to this modification, the first ultrasonic sensor 18A and the second ultrasonic sensor 18B can be installed later on the electromagnetic flowmeter 10 attached to the piping 11.

[0061] The arrangement of the ultrasonic sensors according to this embodiment will be further described with reference to FIG.

[0062] The first ultrasonic sensor 18A and the second ultrasonic sensor 18B are attached to the outer circumferential surface of the pipe 11. That is, the first ultrasonic sensor 18A and the second ultrasonic sensor 18B are installed so as to be in contact with the pipe 11.

[0063] A modified example of the arrangement of ultrasonic sensors according to this embodiment will be described with reference to FIG.

[0064] The first ultrasonic sensor 18A and the second ultrasonic sensor 18B may be attached to the outer circumferential surface of the lining 12 so as to penetrate the piping 11. That is, the first ultrasonic sensor 18A and the second ultrasonic sensor 18B may be installed so as to be in contact with the lining 12.

[0065] Another modified example of the arrangement of ultrasonic sensors according to this embodiment will be described with reference to FIG.

[0066] The first ultrasonic sensor 18A and the second ultrasonic sensor 18B may be attached to the pipe 11 so as to penetrate the pipe 11 and the lining 12. That is, the first ultrasonic sensor 18A and the second ultrasonic sensor 18B may be installed so as to be in contact with the fluid 14. In this modification, in order to prevent the first ultrasonic sensor 18A and the second ultrasonic sensor 18B from generating turbulence in the fluid 14, it is particularly preferable that the first ultrasonic sensor 18A and the second ultrasonic sensor 18B are installed downstream of the first excitation coil 13A and the second excitation coil 13B.

[0067] Regardless of the arrangement shown in any of Figures 4 to 6, the first ultrasonic sensor 18A and the second ultrasonic sensor 18B may be fixed by any joining method, such as adhesive, welding, or a mechanical fastening method such as screw fastening.

[0068] An example of ultrasonic transmission and reception in a full water state by the ultrasonic sensor according to this embodiment will be described with reference to Figs.

[0069] As shown in the upper waveform of FIG. 8, the first ultrasonic sensor 18A and the second ultrasonic sensor 18B, which are installed at the top and bottom of the pipe 11, transmit and receive ultrasonic waves to each other. However, the first ultrasonic sensor 18A and the second ultrasonic sensor 18B transmit ultrasonic waves at different times. As shown in the middle and lower waveforms of FIG. 8, the first ultrasonic sensor 18A and the second ultrasonic sensor 18B transmit and receive ultrasonic waves as sensors alone. For example, in the middle waveform of FIG. 8, a square wave transmitted from the first ultrasonic sensor 18A is reflected at the boundary surface A between the pipe 11 and the lining 12 shown in FIG. 7, and is observed as a received waveform A by the first ultrasonic sensor 18A. Similarly, a reflected wave from the boundary surface B between the lining 12 and the conductive fluid 14 is observed as a received waveform B. The received waveform C in the middle waveform of FIG. 8 is an ultrasonic wave emitted from the first ultrasonic sensor 18A and reflected at the boundary surface C between the conductive fluid 14 and the lining 12 on the bottom side. The propagation time T1 from the transmitted waveform to the received waveform A in the middle part of FIG. 8 is determined by the sound speed and thickness of the pipe 11. Similarly, the time difference (T2-T1) obtained by subtracting T1 from the propagation time T2 from the transmitted waveform to the received waveform B is determined by the sound speed and thickness of the lining 12. Similarly, the time difference (T3-T2) obtained by subtracting T2 from the propagation time T3 from the transmitted waveform to the received waveform C is determined by the sound speed of the conductive fluid 14 and the diameter of the internal space of the pipe 11. Meanwhile, in the lower part of FIG. 8, the square wave transmitted from the second ultrasonic sensor 18B is reflected at the boundary surface D between the pipe 11 and the lining 12 shown in FIG. 7, and is observed as the received waveform D by the second ultrasonic sensor 18B. Similarly, the reflected wave from the boundary surface C between the lining 12 and the conductive fluid 14 is observed as the received waveform C. 8 is an ultrasonic wave emitted from the second ultrasonic sensor 18B and reflected at the boundary surface B between the conductive fluid 14 and the upper lining 12. The propagation time T4 from the transmitted waveform to the received waveform D in the lower part of FIG. 8 is determined by the sound speed and thickness of the piping 11. Similarly, the time difference (T5-T4) obtained by subtracting T4 from the propagation time T5 from the transmitted waveform to the received waveform C is determined by the sound speed and thickness of the lining 12.Similarly, the time difference (T6-T5) obtained by subtracting T5 from the propagation time T6 from the transmission waveform to the reception waveform B is determined by the speed of sound in the conductive fluid 14 and the diameter of the internal space of the pipe 11.

[0070] An example of ultrasonic transmission and reception in a non-full state by the ultrasonic sensor according to this embodiment will be described with reference to Figs.

[0071] As shown in the cross-sectional view of the pipe 11 in FIG. 9, when the pipe 11 is not full of water, the gas phase 22 exists at the top of the pipe 11. When the pipe 11 is not full of water, the ultrasonic waves are strongly reflected at the interface between the gas phase 22 and the fluid 14 due to the difference in acoustic impedance between the liquid phase and the gas phase, and cannot propagate through the gas phase 22. Therefore, as shown in the waveform in the upper part of FIG. 10, the first ultrasonic sensor 18A and the second ultrasonic sensor 18B installed at the top and bottom of the pipe 11, respectively, are in a state where they cannot receive each other's ultrasonic waves. As shown in the waveform in the middle part of FIG. 10, for the ultrasonic waves transmitted from the first ultrasonic sensor 18A, only the received waveforms A and B of the reflected waves from the boundary surface A and the boundary surface B are observed, and the received waveform C of the reflected wave from the boundary surface C, which was seen when the pipe 11 was full of water as shown in FIG. 7, is no longer observed. On the other hand, as shown in the waveform in the lower part of FIG. 10, for the ultrasonic wave transmitted from the second ultrasonic sensor 18B, in addition to the received waveforms D and C of the reflected waves from the boundary surface D and boundary surface C, the received waveform F of the reflected wave from the boundary surface F between the liquid phase and the gas phase is observed. If the sonic velocity of the conductive fluid 14 is known, the liquid level of the non-full fluid 14 can be obtained from the time difference (T6-T5) between the propagation time T6 until the received waveform F is received and the propagation time T5 until the received waveform C is received. The sonic velocity value of the conductive fluid 14 may be set by the user selecting the type of liquid or by directly inputting it into the electromagnetic flowmeter 10. Alternatively, a value calculated from the time difference (T3-T2) in a full state and the known diameter of the internal space of the pipe 11 may be stored and used as the sonic velocity value of the conductive fluid 14.

[0072] The calculator 17 calculates the volumetric flow rate from the voltage measured at the first electrode 15A and the second electrode 15B, but if the calculator 17 were to calculate the volumetric flow rate in the non-full state as in Fig. 9 in the same way as in the full state as in Fig. 7, an error would occur. Therefore, the calculator 17 judges the non-full state by referring to the transmission and reception waveforms of the ultrasonic sensor shown in the upper part of Fig. 10, and corrects the volumetric flow rate calculated on the assumption that the tank is full from the voltage measured at the first electrode 15A and the second electrode 15B in accordance with the liquid level calculated from the time difference (T6-T5) shown in the lower part of Fig. 10. As a result, the volumetric flow rate of the fluid 14 in the non-full state can be calculated.

[0073] An example of ultrasonic transmission and reception by the ultrasonic sensor according to this embodiment in a state where sediment 23 such as earth and sand has accumulated at the bottom of the pipe 11 will be described with reference to Figs.

[0074] As shown in the cross-sectional view of the pipe 11 in FIG. 11, when sediments 23 are accumulated at the bottom of the pipe 11, ultrasonic waves are strongly reflected at the interface between the fluid 14 and the sediments 23 due to the difference in acoustic impedance between the solid phase and the liquid phase. Therefore, as shown in the upper waveform of FIG. 12, the first ultrasonic sensor 18A and the second ultrasonic sensor 18B installed at the top and bottom of the pipe 11, respectively, may be in a state where they cannot receive each other's ultrasonic waves. As shown in the lower waveform of FIG. 12, for ultrasonic waves transmitted from the second ultrasonic sensor 18B, only the received waveforms D and C of the reflected waves from the boundary surfaces D and C are observed, and the received waveform B of the reflected wave from the boundary surface B, which was observed when the water was full as shown in FIG. 7, is no longer observed. On the other hand, as shown in the middle waveform of FIG. 12, for ultrasonic waves transmitted from the first ultrasonic sensor 18A, in addition to the received waveforms A and B of the reflected waves from the boundary surfaces A and B, the received waveform G of the reflected wave from the boundary surface G of the solid phase and the liquid phase is observed. If the sound speed of the conductive fluid 14 is known, the height of the deposit 23 can be obtained from the time difference (T3-T2) between the propagation time T3 until the received waveform G is received and the propagation time T2 until the received waveform B is received. The sound speed value of the conductive fluid 14 may be set by the user selecting the type of liquid or by directly inputting the value into the electromagnetic flowmeter 10. Alternatively, a value calculated from the time difference (T3-T2) in a full water state and the known diameter of the internal space of the pipe 11 may be stored and used as the sound speed value of the conductive fluid 14.

[0075] The calculator 17 calculates the volumetric flow rate from the voltage measured at the first electrode 15A and the second electrode 15B, but if the calculator 17 calculates the volumetric flow rate in the same manner as in the full-water state as in Fig. 7 when sediments 23 have accumulated at the bottom of the pipe 11 as in Fig. 11, an error will occur. Therefore, the calculator 17 judges the presence or absence of sediments 23 by referring to the transmission and reception waveforms of the ultrasonic sensor shown in the upper part of Fig. 12, and corrects the volumetric flow rate calculated on the assumption that the pipe is full from the voltage measured at the first electrode 15A and the second electrode 15B according to the height of the sediments 23 calculated from the time difference (T3-T2) shown in the middle part of Fig. 12. As a result, the volumetric flow rate of the fluid 14 minus the volume of the sediments 23 can be calculated.

[0076] An example of ultrasonic transmission and reception by the ultrasonic sensor according to this embodiment in a state where the pipe 11 is not full of water and where sediments 23 have accumulated at the bottom thereof will be described with reference to FIGS.

[0077] As shown in the cross-sectional view of the pipe 11 in FIG. 13, when the pipe 11 is not full and sediment 23 has accumulated at the bottom, the first ultrasonic sensor 18A and the second ultrasonic sensor 18B installed at the top and bottom of the pipe 11, respectively, cannot receive each other's ultrasonic waves, as shown in the upper waveform of FIG. 14. As shown in the middle waveform of FIG. 14, for the ultrasonic waves transmitted from the first ultrasonic sensor 18A, only the received waveforms A and B of the reflected waves from the boundary surfaces A and B are observed, and the received waveform C of the reflected waves from the boundary surface C, which was observed when the pipe 11 was full as shown in FIG. 7, is not observed. As shown in the lower waveform of FIG. 14, for the ultrasonic waves transmitted from the second ultrasonic sensor 18B, only the received waveforms D and C of the reflected waves from the boundary surfaces D and C are observed, and the received waveform B of the reflected waves from the boundary surface B, which was observed when the pipe 11 was full as shown in FIG. 7, is not observed. The calculator 17 issues an alarm to notify the user of such a non-full state and state where sediment 23 has accumulated at the bottom of the pipe 11. When the inside of the pipe 11 is completely empty and when it is filled with sediment 23, the same ultrasonic waveform is observed, so the calculator 17 issues an alarm.

[0078] The operation of the electromagnetic flowmeter 10 according to this embodiment will be described with reference to FIG.

[0079] In step S1, the first ultrasonic sensor 18A transmits ultrasonic waves along the gravity direction to the inside of the pipe 11. Thereafter, the second ultrasonic sensor 18B transmits ultrasonic waves along the antigravity direction to the inside of the pipe 11. The order of transmitting ultrasonic waves may be reversed. That is, the first ultrasonic sensor 18A may transmit ultrasonic waves after the second ultrasonic sensor 18B transmits ultrasonic waves.

[0080] When the ultrasonic reception waveform of the first ultrasonic sensor 18A includes the reception waveform of the ultrasonic wave transmitted from the second ultrasonic sensor 18B, and when the ultrasonic reception waveform of the second ultrasonic sensor 18B includes the reception waveform of the ultrasonic wave transmitted from the first ultrasonic sensor 18A, the process of step S2 is executed. For example, when the transmission and reception waveform between the first ultrasonic sensor 18A and the second ultrasonic sensor 18B is a waveform as shown in the upper part of FIG. 8, the process of step S2 is executed.

[0081] In other cases, the calculator 17 compares the ultrasonic reception waveform of the first ultrasonic sensor 18A at the current first time point with the ultrasonic reception waveform of the first ultrasonic sensor 18A at the second time point when the inside of the pipe 11 was filled with the fluid 14, and compares the ultrasonic reception waveform of the second ultrasonic sensor 18B at the first time point with the ultrasonic reception waveform of the second ultrasonic sensor 18B at the second time point to determine whether the non-full state and the accumulation state occur simultaneously. The non-full state is a state in which the inside of the pipe 11 is not filled with the fluid 14. The accumulation state is a state in which sediment 23 accumulates at the bottom of the pipe 11. If it is determined that the non-full state and the accumulation state occur simultaneously, the process of step S5 is executed. For example, if the transmission and reception waveform of the first ultrasonic sensor 18A alone and the transmission and reception waveform of the second ultrasonic sensor 18B alone are waveforms like those in the middle and lower parts of FIG. 14, respectively, the process of step S5 is executed.

[0082] If it is determined that the non-full state and the accumulating state do not occur simultaneously, the calculator 17 determines whether the ultrasonic reception waveforms of the second ultrasonic sensor 18B at the first and second points in time include a time difference between the reception waveforms of the reflected waves generated by the ultrasonic waves transmitted from the second ultrasonic sensor 18B entering the fluid 14 and then being reflected at the interface. If such a time difference is included, it can be determined that only the non-full state occurs. That is, the calculator 17 detects the time difference between the reception waveforms of the reflected waves generated by the ultrasonic waves transmitted from the second ultrasonic sensor 18B entering the fluid 14 and then being reflected at the interface, which are included in the ultrasonic reception waveforms of the second ultrasonic sensor 18B at multiple points in time, thereby detecting the non-full state in which the inside of the pipe 11 is not filled with the fluid 14. Then, the process of step S3 is executed. For example, if the transmission and reception waveforms of the second ultrasonic sensor 18B alone are as shown in the lower part of FIG. 10, the process of step S3 is executed.

[0083] If it is determined that the non-full state and the accumulation state do not occur simultaneously and the non-full state is not detected, the calculator 17 determines whether or not the ultrasonic reception waveforms of the first ultrasonic sensor 18A at the first and second time points include a time difference between the reception waveforms of the reflected waves generated by the ultrasonic waves transmitted from the first ultrasonic sensor 18A entering the fluid 14 and then being reflected at the interface. If such a time difference is included, it can be determined that only the accumulation state occurs. That is, the calculator 17 detects the accumulation state by detecting the time difference between the reception waveforms of the reflected waves generated by the ultrasonic waves transmitted from the first ultrasonic sensor 18A entering the fluid 14 and then being reflected at the interface, which are included in the ultrasonic reception waveforms of the first ultrasonic sensor 18A at multiple time points. Then, the process of step S4 is executed. For example, if the transmission and reception waveforms of the first ultrasonic sensor 18A alone are as shown in the middle part of FIG. 12, the process of step S4 is executed.

[0084] In step S2, the calculator 17 determines that the inside of the pipe 11 is filled with the fluid 14. Then, the calculator 17 performs a normal calculation of the flow rate of the fluid 14. The calculator 17 causes the display 24 to display the calculation result.

[0085] In step S3, the calculator 17 determines that the inside of the pipe 11 is not filled with the fluid 14. That is, the calculator 17 detects a non-full state. The calculator 17 then calculates the level of the fluid 14 from the time difference between the transmission of the ultrasonic wave from the second ultrasonic sensor 18B and the reception of the reflected wave. The calculator 17 reflects the calculation result of the level of the fluid 14 in the measurement result of the flow rate of the fluid 14. That is, the calculator 17 corrects the calculation result obtained by performing a normal calculation of the flow rate of the fluid 14 according to the calculated liquid level. The calculator 17 displays the corrected calculation result on the display 24. The calculator 17 outputs an alarm about the non-full state. For example, the calculator 17 displays such an alarm on the display 24.

[0086] In step S4, the calculator 17 determines that the deposits 23 are accumulated at the bottom of the pipe 11. That is, the calculator 17 detects the accumulation state. The calculator 17 then calculates the height of the deposits 23 from the time difference between the transmission of the ultrasonic wave from the first ultrasonic sensor 18A and the reception of the reflected wave. The calculator 17 reflects the calculation result of the height of the deposits 23 in the measurement result of the flow rate of the fluid 14. That is, the calculator 17 corrects the calculation result obtained by performing a normal calculation of the flow rate of the fluid 14 according to the calculated height. The calculator 17 displays the corrected calculation result on the display 24. The calculator 17 outputs an alarm about the accumulation state. For example, the calculator 17 displays such an alarm on the display 24.

[0087] As described above, in this embodiment, whether the inside of the pipe 11 is full of water, specifically, whether there is a gas phase 22 or a deposit 23, is determined based on whether a received waveform between the first ultrasonic sensor 18A and the second ultrasonic sensor 18B is observed as shown in the upper part of FIG. 8. If a received waveform is not observed between the first ultrasonic sensor 18A and the second ultrasonic sensor 18B, and neither the received waveform F nor the received waveform G can be observed by the first ultrasonic sensor 18A and the second ultrasonic sensor 18B alone, it is determined that the inside of the pipe 11 is not full of water and that deposits 23 have accumulated at the bottom of the pipe 11, and an alarm is issued. If either the received waveform F or the received waveform G is observed by the first ultrasonic sensor 18A and the second ultrasonic sensor 18B alone, it is determined whether the inside of the pipe 11 is not full of water or that deposits 23 have accumulated, depending on whether the observed waveform is the received waveform F or the received waveform G. The result of the determination is notified to the user as an alarm and is reflected in the calculation result of the volumetric flow rate of the fluid 14.

[0088] This embodiment can also be applied to monitor the thickness of the lining 12.

[0089] The lining 12 installed inside the pipe 11 is made of insulating resin such as PFA or PTFE. "PFA" is an abbreviation of perfluoroalkoxy alkanes. "PTFE" is an abbreviation of polytetrafluoroethylene. The lining 12 is a member that comes into contact with the conductive fluid 14. If the fluid 14 is a slurry fluid, the lining 12 may wear and become thinner over time. Therefore, it is possible to monitor the thickness of the lining 12 using signals irradiated and received from the first ultrasonic sensor 18A and the second ultrasonic sensor 18B. For example, as shown in the middle part of FIG. 8, the thickness of the lining 12 can be obtained using the difference (T2-T1) in the propagation time from when the first ultrasonic sensor 18A transmits ultrasonic waves to when the received waveforms A and B of the reflected waves generated at the boundary surface A and the boundary surface B are received, and the sound speed of the lining 12 as parameters. The calculator 17 can calculate and output the thickness of the lining 12, and can notify the user by an alarm when the thickness of the lining 12 falls below a user-set value. That is, the calculator 17 may detect a change in the thickness of the lining 12 by detecting a time difference between the received waveforms of the reflected waves generated by the ultrasonic waves transmitted from the first ultrasonic sensor 18A or the second ultrasonic sensor 18B entering the lining 12 and being reflected at the boundary surface between the lining 12 and the fluid 14, which are included in the ultrasonic reception waveforms of the first ultrasonic sensor 18A or the second ultrasonic sensor 18B at multiple points in time. The calculator 17 may output an alarm when it determines that the thickness of the lining 12 is equal to or less than a threshold value. For example, the calculator 17 may cause the display 24 to display such an alarm.

[0090] A modified example of the configuration of the electromagnetic flowmeter 10 will be described with reference to FIG.

[0091] In this embodiment, the electrode surfaces of the electromagnetic flowmeter 10 come into contact with the liquid to measure the flow rate, but the liquid contact surface may be enlarged by employing a surface electrode so that the flow rate can be measured even when the liquid level of the fluid 14 is low, such as less than 50%. That is, the first electrode 15A and the second electrode 15B may be attached to the pipe 11 so as to cover a part of the inner circumferential surface of the lining 12 applied to the inner circumferential surface of the pipe 11 and extend to a position where they come into contact with the fluid 14 even when less than 50% of the inside of the pipe 11 is filled with the fluid 14.

[0092] The present disclosure is not limited to the above-mentioned embodiment. For example, two or more blocks shown in the block diagram may be integrated, or one block may be divided. Instead of executing two or more steps shown in the flowchart in chronological order as described, each step may be executed in parallel or in a different order depending on the processing capacity of the device executing each step, or as necessary. Other modifications are possible without departing from the spirit of the present disclosure. [Explanation of symbols]

[0093] 10 Electromagnetic flowmeter 11 Piping 12 Lining 13A First Excitation Coil 13B Second excitation coil 14 Fluid 15A 1st electrode 15B 2nd electrode 16 Amplifier 17 Arithmetic unit 18A 1st ultrasonic sensor 18B Second ultrasonic sensor 19 Earth Ring 20 Switch 21 Transmitting and receiving circuit 22 Gas Phase 23 Sediment 24 Display

Claims

1. An electromagnetic flowmeter for measuring a flow rate of a fluid flowing through a pipe, A first ultrasonic sensor that transmits ultrasonic waves along the gravity direction to the inside of the pipe and receives ultrasonic waves traveling in an antigravity direction; a second ultrasonic sensor that is spaced apart from the first ultrasonic sensor in the gravity direction and faces the first ultrasonic sensor, transmits ultrasonic waves along a direction opposite to gravity toward the inside of the pipe, and receives ultrasonic waves traveling in the gravity direction; a calculator that determines an internal state of the piping based on ultrasonic reception waveforms of the first ultrasonic sensor and the second ultrasonic sensor; An electromagnetic flow meter comprising:

2. The electromagnetic flowmeter according to claim 1 , wherein the computing unit determines, as the internal state of the pipe, whether the inside of the pipe is filled with the fluid.

3. The electromagnetic flowmeter according to claim 2 , wherein the computing unit outputs an alarm when it determines that the inside of the pipe is not filled with the fluid.

4. 3. The electromagnetic flowmeter according to claim 2, wherein the calculator determines that the inside of the pipe is filled with the fluid when the ultrasonic reception waveform of the first ultrasonic sensor includes the reception waveform of the ultrasonic wave transmitted from the second ultrasonic sensor and the ultrasonic reception waveform of the second ultrasonic sensor includes the reception waveform of the ultrasonic wave transmitted from the first ultrasonic sensor.

5. 3. The electromagnetic flowmeter according to claim 2, wherein the calculator detects a time difference between received waveforms of reflected waves generated when ultrasonic waves transmitted from the second ultrasonic sensor enter the fluid and are reflected at an interface between the fluid and the received waveforms of reflected waves, the time difference being included in ultrasonic received waveforms of the second ultrasonic sensor at multiple points in time, thereby detecting a non-full state in which the inside of the pipe is not filled with the fluid.

6. 6. The electromagnetic flowmeter according to claim 5, wherein when the computing unit detects the non-full state, the computing unit calculates a level of the fluid from a time difference between the transmission of the ultrasonic wave from the second ultrasonic sensor and the reception of the reflected wave, and reflects a calculation result of the fluid level in a measurement result of a flow rate of the fluid.

7. The electromagnetic flowmeter according to claim 1 , wherein the computing unit determines whether or not deposits have accumulated at the bottom of the pipe as the internal state of the pipe.

8. The electromagnetic flowmeter according to claim 7 , wherein the computing unit outputs an alarm when it determines that the deposits have accumulated at the bottom of the pipe.

9. 8. The electromagnetic flowmeter according to claim 7, wherein the calculator detects a time difference between received waveforms of reflected waves generated when ultrasonic waves transmitted from the first ultrasonic sensor enter the fluid and are reflected at an interface between the fluid and the received waveforms of the first ultrasonic sensor at multiple points in time, thereby detecting a state in which the sediments have accumulated at the bottom of the pipe.

10. 10. The electromagnetic flowmeter according to claim 9, wherein when the calculator detects the accumulation state, the calculator calculates the height of the deposit from the time difference between the transmission of the ultrasonic wave from the first ultrasonic sensor and the reception of the reflected wave, and reflects the calculation result of the height of the deposit in the measurement result of the flow rate of the fluid.

11. 2. The electromagnetic flowmeter according to claim 1, wherein the calculator compares an ultrasonic reception waveform of the first ultrasonic sensor at a first point in time with an ultrasonic reception waveform of the first ultrasonic sensor at a second point in time when the inside of the pipe is filled with the fluid, and compares an ultrasonic reception waveform of the second ultrasonic sensor at the first point in time with an ultrasonic reception waveform of the second ultrasonic sensor at the second point in time, thereby determining whether a non-full state in which the inside of the pipe is not filled with the fluid and a pooled state in which sediments have accumulated at the bottom of the pipe are occurring simultaneously.

12. 2. The electromagnetic flowmeter according to claim 1, wherein the calculator detects a time difference between received waveforms of reflected waves generated when ultrasonic waves transmitted from the first ultrasonic sensor or the second ultrasonic sensor enter a lining applied to an inner surface of the piping and are reflected at an interface between the lining and the fluid, the received waveforms being included in ultrasonic received waveforms of the first ultrasonic sensor or the second ultrasonic sensor at multiple points in time, thereby detecting a change in the thickness of the lining.

13. The electromagnetic flowmeter according to claim 12 , wherein the computing unit outputs an alarm when it determines that the thickness of the lining is equal to or smaller than a threshold value.

14. 2. The magnetic flowmeter of claim 1, further comprising a ground ring to which the first ultrasonic sensor and the second ultrasonic sensor are attached.

15. The electromagnetic flowmeter according to claim 1 , wherein the first ultrasonic sensor and the second ultrasonic sensor are attached to an outer circumferential surface of the pipe.

16. The electromagnetic flowmeter according to claim 1 , wherein the first ultrasonic sensor and the second ultrasonic sensor are attached to an outer peripheral surface of a lining applied to an inner peripheral surface of the pipe and pass through the pipe.

17. The electromagnetic flowmeter according to claim 1 , wherein the first ultrasonic sensor and the second ultrasonic sensor are attached to the pipe and penetrate the pipe and a lining applied to an inner peripheral surface of the pipe.

18. 2. The electromagnetic flowmeter according to claim 1, further comprising a pair of electrodes attached to the pipe, covering a portion of an inner surface of a lining applied to the inner surface of the pipe, and extending to a position where the electrodes come into contact with the fluid even when less than 50% of the inside of the pipe is filled with the fluid.

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