Detection controller, electromagnetic flowmeter, and program

Abstract

To take appropriate measures against differential noise contained in a fluid signal.SOLUTION: In an electromagnetic flowmeter 1, a flow rate detector 10 applies to a measurement target fluid FL a first magnetic field with a first frequency and a second magnetic field with a second frequency higher than the first frequency and detects a flow rate signal corresponding to the first magnetic field and the second magnetic field. A detection controller 20 calculates a first flow rate corresponding to the first frequency on the basis of the flow rate signal, calculates a second flow rate corresponding to the second frequency on the basis of the flow rate signal, calculates a third flow rate on the basis of the first flow rate and the second flow rate, and executes predetermined processing when determining that the amount of differential noise contained in the flow rate signal is equal to or greater than a predetermined value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a detection controller, an electromagnetic flowmeter, and a program. [Background technology]

[0002] Electromagnetic flowmeters, which measure the flow rate of a fluid using electromagnetic induction, are widely used in industrial applications. The electromotive force (hereinafter sometimes referred to as the "fluid electromotive force") generated by a fluid (hereinafter sometimes referred to as the "measured fluid") flowing through a measuring tube in which a magnetic field is formed is proportional to the flow rate of the measured fluid, so electromagnetic flowmeters measure the flow rate of the measured fluid (hereinafter sometimes referred to as the "fluid flow rate") based on the fluid electromotive force. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-276470 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-266257 Summary of the Invention [Problem to be solved by the invention]

[0004] One type of noise that may be included in a signal indicating fluid flow rate (hereinafter referred to as a "flow rate signal") is "differential noise." Differential noise is generated by changes in the magnetic field inside the measuring pipe (hereinafter referred to as the "in-pipe magnetic field"). Differential noise occurs in the form of spikes synchronized with the frequency of the excitation current flowing through the excitation coil placed near the measuring pipe, and decays exponentially. Differential noise is also likely to occur when the conductivity of the fluid being measured is low.

[0005] Since the differential noise generated in this manner is a major cause of errors in the measured values ​​of fluid flow rate (hereinafter sometimes referred to as "measurement error"), it is desirable to take appropriate measures against the differential noise.

[0006] Therefore, the present disclosure proposes a technique that can take appropriate measures against differential noise contained in a fluid signal. [Means for solving the problem]

[0007] The detection controller of the present disclosure has a processor and is connected to a flow detector that applies a first magnetic field having a first frequency and a second magnetic field having a second frequency higher than the first frequency to a fluid to be measured and detects a flow rate signal corresponding to the first magnetic field and the second magnetic field. The processor calculates a first flow rate corresponding to the first frequency based on the flow rate signal, calculates a second flow rate corresponding to the second frequency based on the flow rate signal, calculates a third flow rate based on the first flow rate and the second flow rate, and executes a predetermined process when it determines that an amount of differential noise included in the flow rate signal is equal to or greater than a predetermined value. [Effects of the Invention]

[0008] According to the present disclosure, appropriate measures can be taken against differential noise contained in a fluid signal. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating a configuration example of an electromagnetic flowmeter according to a first embodiment of the present disclosure. [Figure 2] FIG. 10 is a diagram illustrating an example of operation of the detection controller according to the first embodiment of the present disclosure. [Figure 3] FIG. 10 is a diagram illustrating an example of the operation of a detection controller according to a second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the following embodiments, the same components or processes will be denoted by the same reference numerals, and redundant description may be omitted.

[0011] [Example 1] <Configuration of an electromagnetic flowmeter> As an excitation method for electromagnetic flowmeters used to measure the flow rate of a fluid to be measured, there is known an excitation method (hereinafter sometimes referred to as a "dual-frequency excitation method") in which a composite magnetic field is formed by simultaneously passing a low-frequency excitation current (hereinafter sometimes referred to as a "low-frequency excitation current") and a high-frequency excitation current (hereinafter sometimes referred to as a "high-frequency excitation current") through an excitation coil. Below, an electromagnetic flowmeter using the dual-frequency excitation method will be taken as an example.

[0012] Fig. 1 is a diagram illustrating a configuration example of an electromagnetic flowmeter according to a first embodiment of the present disclosure. In Fig. 1, the electromagnetic flowmeter 1 includes a flow detector 10, a detection controller 20, a storage unit 30, and a display 40. Examples of the storage unit 30 include a memory and a storage. Examples of the display 40 include an LCD (Liquid Crystal Display).

[0013] The flow rate detector 10 has an exciting coil 11, a first electrode 12, a second electrode 13, and a measuring tube 14. A fluid to be measured FL flows through the measuring tube 14.

[0014] An excitation current obtained by adding a low-frequency excitation current and a high-frequency excitation current (hereinafter sometimes referred to as a "dual-frequency excitation current") is supplied from excitation circuit 24 to excitation coil 11, and in response to the supplied dual-frequency excitation current, an in-pipe magnetic field, which is a composite magnetic field, is formed in measuring tube 14. Because the frequency of the high-frequency excitation current is higher than the frequency of the low-frequency excitation current, a composite magnetic field is formed as the in-pipe magnetic field, which includes a magnetic field having the frequency of the low-frequency excitation current (hereinafter sometimes referred to as a "low-frequency magnetic field") and a magnetic field having the frequency of the high-frequency excitation current (hereinafter sometimes referred to as a "high-frequency magnetic field"). Therefore, in measuring tube 14, a composite magnetic field consisting of a low-frequency magnetic field and a high-frequency magnetic field is applied to the fluid FL to be measured.

[0015] The first electrode 12 and the second electrode 13 detect a signal of the fluid electromotive force proportional to the magnetic field inside the pipe and the flow rate of the fluid to be measured as a flow rate signal, and output the detected flow rate signal to the detection controller 20. Because the magnetic field inside the pipe is a composite magnetic field consisting of a low-frequency magnetic field and a high-frequency magnetic field, the first electrode 12 and the second electrode 13 detect a flow rate signal (hereinafter sometimes referred to as a "dual-frequency flow rate signal") that is the sum of the flow rate signal corresponding to the low-frequency magnetic field and the flow rate signal corresponding to the high-frequency magnetic field.

[0016] On the other hand, the detection controller 20 has an amplifier 21, a converter 22, a processor 23, and an excitation circuit 24. The processor 23 is connected to a storage unit 30 and a display 40. Examples of the processor 23 include a CPU (Central Processing Unit) and an MPU (Micro Processing Unit).

[0017] The two-frequency flow rate signal detected by the flow rate detector 10 is input to the amplifier 21. The amplifier 21 amplifies the two-frequency flow rate signal and outputs the amplified two-frequency flow rate signal to the converter 22.

[0018] The converter 22 converts the analog two-frequency flow rate signal into a digital two-frequency flow rate signal, and outputs the digital two-frequency flow rate signal to the processor 23.

[0019] The processor 23 calculates the flow rate corresponding to the frequency of the low-frequency magnetic field (hereinafter sometimes referred to as "low-frequency flow rate LF") by performing a predetermined calculation on the two-frequency flow rate signal at a timing synchronized with the frequency of the low-frequency excitation current.

[0020] In addition, the processor 23 calculates the flow rate corresponding to the frequency of the high-frequency magnetic field (hereinafter sometimes referred to as the "high-frequency flow rate HF") by performing a predetermined calculation on the two-frequency flow rate signal at a timing synchronized with the frequency of the high-frequency excitation current.

[0021] For example, the processor 23 calculates the current low-frequency flow rate LF_LPF(n) after low-pass filtering according to equation (1), and calculates the current high-frequency flow rate HF_HPF(n) after high-pass filtering according to equation (2). In equation (1), LF_LPF(n-1) is the previously calculated low-frequency flow rate after low-pass filtering, Kt is the damping coefficient, and LF(n) is the current low-frequency flow rate before low-pass filtering. Also, in equation (2), HF(n) is the current high-frequency flow rate before high-pass filtering, and HF_LPF(n) is the current high-frequency flow rate after low-pass filtering. LF_LPF(n)=LF_LPF(n-1)+Kt(LF(n)- LF_LPF(n-1)) …(1) HF_HPF(n)=HF(n)-HF_LPF(n) …(2)

[0022] The processor 23 also calculates a flow rate corresponding to the dual-frequency excitation current (hereinafter sometimes referred to as a "dual-frequency flow rate DF") by adding the low-frequency flow rate LF and the high-frequency flow rate HF together at a timing synchronized with the frequency of the high-frequency excitation current. Then, the processor 23 displays the calculated dual-frequency flow rate DF on the display 40. For example, the processor 23 calculates the current dual-frequency flow rate DF(n) according to equation (3). DF(n)=LF_LPF(n)+HF_HPF(n) …(3)

[0023] Furthermore, the processor 23 executes a predetermined process when it is determined that the amount of differential noise included in the two-frequency flow rate signal (hereinafter sometimes referred to as "two-frequency differential noise amount") is equal to or greater than a predetermined value.

[0024] The excitation circuit 24 supplies a two-frequency excitation current to the excitation coil 11 based on an excitation control signal from the processor 23 .

[0025] <Detection controller operation> 2 is a diagram illustrating an example of the operation of the detection controller according to the first embodiment of the present disclosure. Here, differential noise is fluid noise generated by changes in the magnetic field inside the tube. It occurs in synchronization with the frequency of the excitation current and decays exponentially, affecting the stability of the zero point. Therefore, differential noise causes output drift, particularly zero drift, as shown in FIG. 2.

[0026] 2, when the processor 23 detects that the low-frequency flow rate LF has been zero for a predetermined time TZ, starting from a first time point T1 when the low-frequency flow rate LF becomes zero, the processor 23 determines whether the amount of second-frequency differential noise is equal to or greater than a predetermined value at a second time point T2 after the predetermined time TZ has elapsed from the first time point T1. If the low-frequency flow rate LF becomes greater than zero before the predetermined time TZ has elapsed (i.e., before reaching the second time point T2), the processor 23 stops measuring the predetermined time TZ and restarts measuring the predetermined time TZ starting from the first time point T1 when the low-frequency flow rate LF becomes zero again.

[0027] Then, when the processor 23 determines that the amount of two-frequency differential noise is equal to or greater than the predetermined value at the second time point T2, the processor 23 executes at least one of the following predetermined processing examples 1, 2, and 3.

[0028] <Prescribed processing example 1> When processor 23 determines that the amount of two-frequency differential noise is equal to or greater than a predetermined value at second time point T2, processor 23 performs a process of issuing a warning as a predetermined process. For example, processor 23 causes display 40 to display a warning message.

[0029] <Prescribed processing example 2> When the processor 23 determines that the two-frequency differential noise amount is equal to or greater than the predetermined value at the second time point T2, the processor 23 performs a process of displaying the differential noise amount on the display 40 as the predetermined process.

[0030] <Prescribed processing example 3> When the processor 23 determines that the amount of two-frequency differential noise is equal to or greater than a predetermined value at the second time point T2, the processor 23 performs, as a predetermined process, a process of storing the amount of differential noise in the storage unit 30. For example, the processor 23 stores the current date and time and the amount of differential noise in the storage unit 30 in association with each other.

[0031] Furthermore, the processor 23 determines whether the amount of two-frequency differential noise is equal to or greater than a predetermined value in accordance with one of the following determination examples 1 to 3.

[0032] <Judgment Example 1> The processor 23 determines that the amount of two-frequency differential noise is greater than or equal to a predetermined value when the difference between the average value of the low-frequency flow rate LF and the average value of the two-frequency flow rate DF over a predetermined time TZ from the first point in time T1 when the low-frequency flow rate LF becomes zero is greater than or equal to a threshold value at the second point in time T2.

[0033] <Judgment Example 2> The processor 23 determines that the amount of two-frequency differential noise is greater than or equal to a predetermined value when the difference between the average value of the low-frequency flow rate LF and the average value of the high-frequency flow rate HF over a predetermined time TZ from the first point in time T1 when the low-frequency flow rate LF becomes zero is greater than or equal to a threshold value at the second point in time T2.

[0034] <Judgment Example 3> The processor 23 determines that the amount of two-frequency differential noise is greater than or equal to a predetermined value when the difference between the average value of the high-frequency flow rate HF and zero at a predetermined time TZ from the first point in time T1 when the low-frequency flow rate LF becomes zero is greater than or equal to a threshold value at the second point in time T2.

[0035] The first embodiment has been described above.

[0036] [Example 2] In the second embodiment, when the processor 23 determines that the amount of two-frequency differential noise is equal to or greater than a predetermined value at the second time point T2, it executes the predetermined process shown in the following predetermined process example 4. The processor 23 may execute at least one of the predetermined processes shown in the predetermined process examples 1, 2, and 3 of the first embodiment in combination with the predetermined process shown in the following predetermined process example 4.

[0037] <Prescribed processing example 4> 3 is a diagram illustrating an example of the operation of a detection controller according to Example 2 of the present disclosure. Below, differences from Example 1 will be described, and descriptions of the same points as Example 1 will be omitted.

[0038] As shown in FIG. 3, when the processor 23 determines that the amount of second frequency differential noise is equal to or greater than a predetermined value at the second time point T2, the processor 23 performs a process of correcting the high frequency flow rate HF to zero as a predetermined process.

[0039] The second embodiment has been described above.

[0040] [Example 3] All or part of the processes in the detection controller 20 may be realized by having the processor 23 execute a program corresponding to each process. For example, the program corresponding to each process in the detection controller 20 may be stored in the storage unit 30. Alternatively, for example, the program corresponding to each process in the detection controller 20 may be stored in a program server connected to the detection controller 20 via a network, downloaded from the program server to the detection controller 20, and executed. Alternatively, for example, the program corresponding to each process in the detection controller 20 may be stored in a recording medium readable by the detection controller 20, read from the recording medium, and executed.

[0041] The third embodiment has been described above.

[0042] As described above, the detection controller (detection controller 20 of the embodiment) of the present disclosure includes a processor (processor 23 of the embodiment) and is connected to a flow detector (flow detector 10 of the embodiment) that applies a first magnetic field (low-frequency magnetic field of the embodiment) having a first frequency and a second magnetic field (high-frequency magnetic field of the embodiment) having a second frequency higher than the first frequency to a fluid to be measured (fluid to be measured FL of the embodiment). The flow detector detects a flow signal (dual-frequency flow signal of the embodiment) corresponding to the first and second magnetic fields. The processor calculates a first flow rate (low-frequency flow rate LF of the embodiment) corresponding to the first frequency based on the flow signal, calculates a second flow rate (high-frequency flow rate HF of the embodiment) corresponding to the second frequency based on the flow signal, and calculates a third flow rate (dual-frequency flow rate DF of the embodiment) based on the first and second flow rates. The processor also executes a predetermined process when it determines that the amount of differential noise (dual-frequency differential noise of the embodiment) included in the flow signal is equal to or greater than a predetermined value.

[0043] For example, when the processor determines that the amount of differential noise is equal to or greater than a predetermined value, it issues a warning as a predetermined process, thereby informing the operator that there is a problem with the flow detector, and allowing the operator to take appropriate measures.

[0044] Furthermore, for example, when the processor determines that the amount of differential noise is equal to or greater than a predetermined value, the processor may perform a predetermined process of displaying the amount of differential noise on a display connected to the processor (display 40 in the embodiment). This notifies the operator that the error of the flow detector is increasing, enabling the operator to take appropriate measures according to the amount of differential noise.

[0045] Furthermore, for example, when the processor determines that the amount of differential noise is equal to or greater than a predetermined value, the processor performs a process of storing the amount of differential noise in a storage unit (storage unit 30 in the embodiment) connected to the processor as a predetermined process. By doing so, the amount of differential noise that is equal to or greater than the predetermined value can be recorded, and it becomes possible to take appropriate measures based on the analysis results of the amount of differential noise.

[0046] Furthermore, for example, when the processor determines that the amount of differential noise is equal to or greater than a predetermined value, it performs a predetermined process of correcting the second flow rate to zero. Because the effects of zero drift and the like due to differential noise are greater at the second flow rate, this allows appropriate measures to be automatically taken to suppress measurement errors that occur due to differential noise.

[0047] As described above, the detection controller of the present disclosure can take appropriate measures against differential noise contained in the fluid signal.

[0048] In addition, some examples of combinations in the techniques of the present disclosure are described below.

[0049] (1) A detection controller connected to a flow detector that applies a first magnetic field having a first frequency and a second magnetic field having a second frequency higher than the first frequency to a fluid to be measured and detects a flow signal corresponding to the first magnetic field and the second magnetic field, the detection controller comprising: a processor that calculates a first flow rate corresponding to the first frequency based on the flow signal; calculates a second flow rate corresponding to the second frequency based on the flow signal; calculates a third flow rate based on the first flow rate and the second flow rate; and executes a predetermined process when it determines that the amount of differential noise included in the flow signal is equal to or greater than a predetermined value.

[0050] (2) The detection controller according to (1), wherein the processor performs the predetermined processing of issuing a warning when it determines that the amount of differential noise is equal to or greater than the predetermined value.

[0051] (3) A detection controller as described in (1) or (2), wherein when the processor determines that the amount of differential noise is greater than or equal to the predetermined value, the processor performs the predetermined processing of displaying the amount of differential noise on a display connected to the processor.

[0052] (4) A detection controller described in any one of (1) to (3), wherein when the processor determines that the amount of differential noise is greater than or equal to the predetermined value, the processor performs the predetermined processing of storing the amount of differential noise in a memory unit connected to the processor.

[0053] (5) A detection controller described in any one of (1) to (4), wherein the processor performs the predetermined processing of correcting the second flow rate to zero when it determines that the amount of differential noise is greater than or equal to the predetermined value.

[0054] (6) A detection controller described in any one of (1) to (5), wherein the processor determines that the amount of differential noise is greater than or equal to the predetermined value when the difference between the average value of the first flow rate and the average value of the third flow rate over a predetermined time period from the point at which the first flow rate becomes zero is greater than or equal to a threshold value.

[0055] (7) A detection controller described in any one of (1) to (5), wherein the processor determines that the amount of differential noise is greater than or equal to the predetermined value when the difference between the average value of the first flow rate and the average value of the second flow rate over a predetermined time period from the point at which the first flow rate becomes zero is greater than or equal to a threshold value.

[0056] (8) A detection controller described in any one of (1) to (5), wherein the processor determines that the amount of differential noise is greater than or equal to the predetermined value when the difference between the average value of the second flow rate and zero for a predetermined time period from the time the first flow rate becomes zero is greater than or equal to a threshold value.

[0057] (9) An electromagnetic flow meter comprising: a flow detector that applies a first magnetic field having a first frequency and a second magnetic field having a second frequency higher than the first frequency to a fluid to be measured and detects a flow signal corresponding to the first magnetic field and the second magnetic field; and a detection controller that is connected to the flow detector and calculates a first flow rate corresponding to the first frequency based on the flow signal, calculates a second flow rate corresponding to the second frequency based on the flow signal, calculates a third flow rate based on the first flow rate and the second flow rate, and executes a predetermined process when it is determined that an amount of differential noise included in the flow signal is equal to or greater than a predetermined value.

[0058] (10) A program usable in a detection controller connected to a flow detector that applies a first magnetic field having a first frequency and a second magnetic field having a second frequency higher than the first frequency to a fluid to be measured and detects a flow signal corresponding to the first magnetic field and the second magnetic field, a program for causing a processor included in the detection controller to execute a process of calculating a first flow rate corresponding to the first frequency based on the flow rate signal, calculating a second flow rate corresponding to the second frequency based on the flow rate signal, calculating a third flow rate based on the first flow rate and the second flow rate, and executing a predetermined process when it is determined that an amount of differential noise included in the flow rate signal is equal to or greater than a predetermined value. [Explanation of symbols]

[0059] 1 Electromagnetic flowmeter 10 Flow detector 20 Detection Controller 30 Storage section 40 Display 21 Amplifier 22 Converter 23 processors 24 Excitation circuit

Claims

1. a detection controller connected to a flow rate detector that applies a first magnetic field having a first frequency and a second magnetic field having a second frequency higher than the first frequency to a fluid to be measured and detects a flow rate signal corresponding to the first magnetic field and the second magnetic field, a processor that calculates a first flow rate corresponding to the first frequency based on the flow rate signal, calculates a second flow rate corresponding to the second frequency based on the flow rate signal, calculates a third flow rate based on the first flow rate and the second flow rate, and executes a predetermined process when it is determined that an amount of differential noise included in the flow rate signal is equal to or greater than a predetermined value; A detection controller comprising:

2. the processor performs, as the predetermined process, a process of issuing a warning when it is determined that the amount of differential noise is equal to or greater than the predetermined value; The detection controller of claim 1 .

3. when it is determined that the amount of differential noise is equal to or greater than the predetermined value, the processor performs, as the predetermined process, a process of displaying the amount of differential noise on a display connected to the processor. The detection controller of claim 1 .

4. when it is determined that the amount of differential noise is equal to or greater than the predetermined value, the processor performs, as the predetermined process, a process of storing the amount of differential noise in a storage unit connected to the processor. The detection controller of claim 1 .

5. When the processor determines that the amount of differential noise is equal to or greater than the predetermined value, the processor performs the predetermined process of correcting the second flow rate to zero. The detection controller of claim 1 .

6. the processor determines that the amount of differential noise is equal to or greater than the predetermined value when a difference between an average value of the first flow rate and an average value of the third flow rate for a predetermined time period from when the first flow rate becomes zero is equal to or greater than a threshold value; The detection controller of claim 1 .

7. the processor determines that the amount of differential noise is equal to or greater than the predetermined value when a difference between an average value of the first flow rate and an average value of the second flow rate for a predetermined time period from when the first flow rate becomes zero is equal to or greater than a threshold value; The detection controller of claim 1 .

8. the processor determines that the amount of differential noise is equal to or greater than the predetermined value when a difference between an average value of the second flow rate and zero for a predetermined time period from when the first flow rate becomes zero is equal to or greater than a threshold value; The detection controller of claim 1 .

9. a flow rate detector that applies a first magnetic field having a first frequency and a second magnetic field having a second frequency higher than the first frequency to a fluid to be measured and detects a flow rate signal corresponding to the first magnetic field and the second magnetic field; a detection controller connected to the flow detector, which calculates a first flow rate corresponding to the first frequency based on the flow signal, calculates a second flow rate corresponding to the second frequency based on the flow signal, calculates a third flow rate based on the first flow rate and the second flow rate, and executes a predetermined process when it is determined that an amount of differential noise included in the flow signal is equal to or greater than a predetermined value; An electromagnetic flow meter comprising:

10. A program usable in a detection controller connected to a flow detector that applies a first magnetic field having a first frequency and a second magnetic field having a second frequency higher than the first frequency to a fluid to be measured and detects a flow rate signal corresponding to the first magnetic field and the second magnetic field, A processor included in the detection controller calculating a first flow rate corresponding to the first frequency based on the flow rate signal; calculating a second flow rate corresponding to the second frequency based on the flow rate signal; calculating a third flow rate based on the first flow rate and the second flow rate; When it is determined that the amount of differential noise contained in the flow rate signal is equal to or greater than a predetermined value, a predetermined process is executed. A program for executing a process.

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