Electromagnetic flowmeter

Abstract

To recognize a state of a signal electrode of an electromagnetic flowmeter in use.SOLUTION: An electromagnetic flowmeter comprises: a pair of signal electrodes 101a, 101b; a consumption detection electrode 102; and a consumption detection circuit 103. Each of the signal electrodes 101a, 101b, and the consumption detection electrode 102 is made of a metal film made of the same corrosion resistant metal. The signal electrodes 101a, 101b, and the consumption detection electrode 102 are arranged in a measurement tube 111 through which fluid to be measured flows.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electromagnetic flowmeter. [Background technology]

[0002] One type of flowmeter that measures the flow rate of a fluid is the electromagnetic flowmeter, which uses the electromotive force generated by a fluid flowing in a magnetic field. Electromagnetic flowmeters are widely used because they have high measurement accuracy, and because they have no mechanical moving parts and no obstacles in the measurement tube, they do not affect the flow.

[0003] The electromagnetic flowmeter includes an excitation coil that applies a magnetic field in a direction perpendicular to the flow direction of the fluid flowing through the measuring tube, and a signal electrode that is provided on the inner peripheral surface of the measuring tube and faces the direction perpendicular to the applied magnetic field. The electromagnetic flowmeter is configured so that an electromotive force generated in the fluid flowing through the measuring tube by the applied magnetic field is extracted by the signal electrode.

[0004] Incidentally, electromagnetic flowmeters are often used for fluids that contain slurry. In addition, in environments where corrosion resistance is required, precious metal electrodes made of highly corrosion-resistant metals are used as detection electrodes. However, precious metals are expensive, so in order to reduce their usage, corrosion-resistant electrodes are used in which the surface of the electrode body made of a base metal is covered with a layer of precious metal. When the precious metal layer of this corrosion-resistant electrode wears away due to contact with the slurry or corrosion, the base metal of the electrode body is exposed. In this state, flow measurement becomes impossible due to corrosion noise.

[0005] To address the above-mentioned problems with corrosion-resistant electrodes, an electrode has been proposed in which the electrode body made of a base metal is covered with an insulating layer such as alumina, and the surface of the insulating layer is further covered with a layer of a precious metal (see Patent Document 1). With this electrode, even if the precious metal layer is worn away due to contact with the slurry or corrosion, the insulating layer is exposed, and no electrical corrosion noise is generated. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6754312 Summary of the Invention [Problem to be solved by the invention]

[0007] However, even in the above-mentioned conventional electrodes, as the precious metal layer is reduced due to wear, the wetted area of ​​the precious metal layer is reduced. Measurement noise, called flow noise, is proportional to the inverse of the above-mentioned wetted area. Therefore, due to the reduction in wetted area caused by the reduction in the precious metal layer, this electrode will eventually reach the end of its life. It is important to replace such electrodes at an appropriate time. However, the above-mentioned state of the electrode cannot be observed visually during use, and it is difficult to predict the time to replace it.

[0008] The present invention has been made to solve the above problems, and an object of the present invention is to make it possible to grasp the state of the signal electrodes of an electromagnetic flow meter during use. [Means for solving the problem]

[0009] The electromagnetic flowmeter of the present invention comprises a pair of signal electrodes that come into contact with the fluid to be measured to which a magnetic field is applied, and extract an electromotive force corresponding to the flow rate of the fluid, a wear detection electrode that comes into contact with the fluid, and a wear detection circuit configured to detect wear of the wear detection electrode based on electrical characteristics detected by the wear detection electrode, wherein the signal electrode is composed of a metal film made of a corrosion-resistant metal formed on the surface of a first electrode body having an insulating surface, and the wear detection electrode is composed of a metal film made of the same corrosion-resistant metal formed on the surface of a second electrode body having an insulating surface.

[0010] In one configuration example of the above-mentioned electromagnetic flowmeter, the first electrode body and the second electrode body are made of an insulating material, or the first electrode body and the second electrode body in the liquid contact area are made of a conductive material whose surface is coated with an insulating material.

[0011] In one configuration example of the above-mentioned electromagnetic flowmeter, the wear detection circuit detects wear of the metal film of the signal electrode based on a change in the electrical characteristics.

[0012] In one configuration example of the above-mentioned electromagnetic flowmeter, the wear detection circuit detects wear of the metal film of the signal electrode based on a change in the electrical characteristics exceeding a preset standard.

[0013] In one configuration example of the above-described electromagnetic flowmeter, the electrical characteristic is a resistance value.

[0014] In one configuration example of the above-mentioned electromagnetic flowmeter, the electrical characteristic is a current value or a capacitance.

[0015] In one configuration example of the above-mentioned electromagnetic flowmeter, the consumable detection electrode is in contact with the fluid to be measured to which a magnetic field is applied.

[0016] In one configuration example of the above-mentioned electromagnetic flowmeter, a flow rate measuring circuit is provided that is configured to obtain a flow rate based on an electromotive force. Effect of the Invention

[0017] As described above, according to the present invention, wear of the signal electrode is detected based on the electrical characteristics detected by the wear detection electrode made of a metal film made of the same corrosion-resistant metal as the signal electrode, so that the condition of the signal electrode of the electromagnetic flowmeter during use can be grasped. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram showing the configuration of an electromagnetic flowmeter according to an embodiment of the present invention. [Figure 2A] FIG. 2A is a cross-sectional view showing a partial configuration of a signal electrode 101a of an electromagnetic flowmeter according to an embodiment of the present invention. [Figure 2B] FIG. 2B is a cross-sectional view showing a partial configuration of the signal electrode 101a of the electromagnetic flowmeter according to the embodiment of the present invention. [Figure 3A]FIG. 3A is a configuration diagram showing a partial configuration of the depletion detection electrode 102 of the electromagnetic flowmeter according to the embodiment of the present invention. [Figure 3B] FIG. 3B is a cross-sectional view showing a partial configuration of depletion detection electrode 102 of the electromagnetic flowmeter according to the embodiment of the present invention. [Figure 4] FIG. 4 is a configuration diagram showing a partial configuration of the signal electrode 101a and the depletion detection electrode 102 of the electromagnetic flowmeter according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] An electromagnetic flowmeter according to an embodiment of the present invention will now be described with reference to FIGS.

[0020] This electromagnetic flowmeter includes a pair of signal electrodes 101a and 101b, a wear detection electrode 102, and a wear detection circuit 103, and the signal electrodes 101a and 101b and the wear detection electrode 102 are made of a metal film made of the same corrosion-resistant metal. The signal electrodes 101a and 101b and the wear detection electrode 102 are provided in a measuring tube 111 through which the fluid to be measured flows. In addition, a lining 112 made of an insulating material such as resin is formed on the inner wall surface of the measuring tube 111.

[0021] A pair of signal electrodes 101a, 101b come into contact with the fluid to be measured to which a magnetic field is applied by excitation coil 105, and extract an electromotive force corresponding to the flow rate of the fluid. Signal electrode 101a is attached to measuring tube 111 by attachment portion 113a, and signal electrode 101b is attached to measuring tube 111 by attachment portion 113b. In addition, signal electrodes 101a, 101b are connected to flow rate measuring circuit 104. Flow rate measuring circuit 104 calculates the flow rate based on the electromotive force extracted by signal electrodes 101a, 101b.

[0022] The wear detection electrode 102 is provided in a state where it comes into contact with the fluid to be measured, and is attached to the measurement tube 111 by an attachment part 114. The wear detection electrode 102 also comes into contact with the fluid to be measured to which a magnetic field is applied. The wear detection circuit 103 detects the wear of the wear detection electrode 102 based on the electrical characteristics detected by the wear detection electrode 102.

[0023] The wear detection circuit 103 detects wear of the metal film of the wear detection electrode 102 based on, for example, a change in the electrical characteristic detected by the wear detection electrode 102. The wear detection circuit 103 can detect wear of the metal film of the wear detection electrode based on, for example, a state in which the change in the electrical characteristic detected by the wear detection electrode 102 exceeds a set standard. The above-mentioned electrical characteristic can be, for example, a resistance value. The above-mentioned electrical characteristic can also be a current value.

[0024] The signal electrodes 101a and 101b are made of a metal film made of a corrosion-resistant metal formed on the surface of a first electrode body having an insulating surface, while the wear detection electrode 102 is made of a metal film made of the same corrosion-resistant metal as the signal electrodes 101a and 101b, formed on the surface of a second electrode body having an insulating surface.

[0025] For example, as shown in FIG. 2A, the signal electrode 101a is formed on the surface of the first electrode body 121. The signal electrode 101a is exposed to the internal space of the measuring tube 111 in the liquid contact area 122 and contacts the fluid to be measured. The first electrode body 121 can be made of an insulating material such as ceramics or insulating resin. The surface of the first electrode body 121 made of an insulating material is also made of an insulating material. The signal electrode 101a can be made of a precious metal such as Pt or Au. The signal electrode 101a can also be made of Ti, Ta, WC, or the like.

[0026] Also, as shown in FIG. 2B, the signal electrode 101a may be formed on the surface of a first electrode body 121a made of a conductive material and having a surface covered with an insulating layer 123 made of an insulating material. In this configuration, the liquid contact area 122 of the first electrode body 121a is covered with the insulating layer 123. The insulating layer 123 is formed to cover the liquid contact area of ​​the first electrode body 121a and is made of an insulating material. The insulating layer 123 may be made of a metal oxide such as aluminum oxide. The signal electrode 101b has the same configuration as the above-mentioned signal electrode 101a.

[0027] As shown in FIG. 3A, the wear detection electrode 102 is formed on the surface of the second electrode body 131. The wear detection electrode 102 is exposed to the internal space of the measuring tube 111 in the liquid contact area 132 and comes into contact with the fluid to be measured. The second electrode body 131 can be made of an insulating material such as ceramics or insulating resin. The surface of the second electrode body 131 made of an insulating material is also made of an insulating material. The wear detection electrode 102 can be made of a precious metal such as Pt or Au. The wear detection electrode 102 can also be made of Ti, Ta, WC, or the like. The wear detection electrode 102 is made of a metal film made of the same corrosion-resistant metal as the signal electrodes 101a and 101b.

[0028] For example, by forming the wear detection electrode 102 in a wiring pattern and connecting it to the wear detection circuit 103 via wiring 103a, the wear detection circuit 103 can detect when the wear detection electrode 102 becomes broken due to wear in the liquid contact area 132.

[0029] 3B, the wear detection electrode 102 may be formed on the surface of a second electrode body 131 made of a conductive material and having a surface covered with an insulating layer 133 made of an insulating material. In this configuration, the liquid contact area 122 of the second electrode body 131 is covered with the insulating layer 133. The insulating layer 133 is formed to cover the liquid contact area of ​​the second electrode body 131 and is made of an insulating material. The insulating layer 133 may be made of a metal oxide such as aluminum oxide.

[0030] 4, the wear detection electrode 102 and, for example, the signal electrode 101a can be formed on the electrode body 141, which is an integrated body of the first electrode body and the second electrode body. The electrode body 141 can be made of, for example, an insulating material such as ceramics or insulating resin. The signal electrode 101a and the wear detection electrode 102 come into contact with the fluid to be measured in the liquid contact area 142. For example, the liquid contact surfaces of the signal electrode 101a and the wear detection electrode 102 in the liquid contact area 142, which face the center of the measuring tube 111, can be arranged on the same plane. Wear of the wear detection electrode 102 in the liquid contact area 142 is detected by the wear detection circuit 103. For example, when the wear detection electrode 102 formed in a wiring pattern in the liquid contact area 142 becomes a broken line due to wear, this is detected by the wear detection circuit 103. As described above, it is believed that by arranging the liquid contact surfaces of the signal electrode 101a and the wear detection electrode 102 on the same plane, it is possible to ensure that the state of corrosion received from the fluid to be measured is similar for both electrodes.

[0031] As described above, according to the embodiment, the wear detection electrode 102 is made of a metal film made of the same corrosion-resistant metal as the signal electrodes 101a and 101b. Therefore, the metal film of the wear detection electrode 102 wears away during actual use, just like the signal electrodes 101a and 101b. Therefore, if wear of the metal film of the wear detection electrode 102 is detected by the wear detection circuit 103, this indicates wear of the metal films of the signal electrodes 101a and 101b. Therefore, detection of wear of the metal film of the wear detection electrode 102 by the wear detection circuit 103 makes it possible to notify the user of the need to replace the signal electrodes 101a and 101b and to predict the replacement period.

[0032] Also, for example, the metal film constituting the depletion detection electrode 102 in the liquid contact area can be formed thinner than the metal film constituting the signal electrodes 101a and 101b. In this state, the depletion detection electrode 102 is worn out and broken faster, so that when the depletion detection circuit 103 detects a broken body, the metal film remains on the signal electrodes 101a and 101b, making it possible to detect the flow rate. By replacing the signal electrodes 101a and 101b in this state, it becomes possible to suppress the occurrence of abnormalities in the flow rate measurement results.

[0033] As described above, according to the present invention, wear of the signal electrode is detected based on the electrical characteristics detected by the wear detection electrode made of a metal film made of the same corrosion-resistant metal as the signal electrode, so that the condition of the signal electrode of the electromagnetic flowmeter during use can be grasped.

[0034] It should be noted that the present invention is not limited to the above-described embodiments, and it is apparent that many modifications and combinations can be made by a person having ordinary knowledge in the art within the technical concept of the present invention. [Explanation of symbols]

[0035] 101a, 101b...signal electrode, 102...wear detection electrode, 103...wear detection circuit, 104...flow rate measurement circuit, 105...excitation coil, 111...measuring tube, 112...lining, 113a, 113b...mounting portion, 114...mounting portion, 121, 121a...first electrode body, 122...liquid contact area, 123...insulating layer, 131...second electrode body, 132...liquid contact area, 133...insulating layer, 141...electrode body, 142...liquid contact area.

Claims

1. a pair of signal electrodes that are in contact with the fluid to be measured to which a magnetic field is applied and that extract an electromotive force corresponding to the flow rate of the fluid; a consumable detection electrode in contact with the fluid; a wear detection circuit configured to detect wear of the wear detection electrode based on an electrical characteristic detected by the wear detection electrode; Equipped with the signal electrode is formed of a metal film made of a corrosion-resistant metal and formed on the surface of a first electrode body having an insulating surface; The wear detection electrode is made of a metal film made of the corrosion-resistant metal formed on the surface of a second electrode body having an insulating surface.

1. An electromagnetic flowmeter comprising:

2. 2. The electromagnetic flowmeter according to claim 1, The first electrode body and the second electrode body are made of an insulating material. or The first electrode body and the second electrode body in the liquid contact area are made of a conductive material whose surface is covered with an insulating material.

1. An electromagnetic flowmeter comprising:

3. 3. The electromagnetic flowmeter according to claim 1, The wear detection circuit detects wear of the wear detection electrode based on a change in the electrical characteristic.

4. 4. The electromagnetic flowmeter according to claim 3, The wear detection circuit detects wear of the wear detection electrode based on a change in the electrical characteristic exceeding a preset standard.

5. The electromagnetic flowmeter according to any one of claims 1 to 4, The electromagnetic flowmeter, wherein the electrical characteristic is a resistance value.

6. The electromagnetic flowmeter according to any one of claims 1 to 4, The electromagnetic flowmeter, wherein the electrical characteristic is a current value or a capacitance.

7. The electromagnetic flowmeter according to any one of claims 1 to 6, 13. An electromagnetic flowmeter, comprising: a first electrode for detecting a flow of the fluid; a second electrode for detecting a flow of the fluid;

8. The electromagnetic flowmeter according to any one of claims 1 to 7, An electromagnetic flowmeter comprising a flow rate measuring circuit configured to determine a flow rate based on the electromotive force.

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