Electromagnetic flow meter and method for manufacturing the same

Abstract

An electromagnetic flow meter comprises: a measuring tube (20) through which a fluid to be measured flows; a magnet coil (30) arranged outside the measuring tube (20) for generating a magnetic field; and electrodes (10) which are arranged on the measuring tube (20) and are used for measuring the voltage of the fluid induced in the magnetic field, each electrode (10) being coated with a protective layer. A method for applying a protective layer to an electromagnetic flow meter is also provided.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to electromagnetic flow meters for monitoring fluid flow. Embodiments of the present disclosure also relate to methods for manufacturing electromagnetic flow meters. Background Art

[0002] Electromagnetic flowmeter (EMF) is a device used to measure the flow rate of fluids and is widely used in different industries.

[0003] When a conductor moves through a magnetic field, a voltage is induced in the conductor. This principle can be applied to conductive fluids. In particular, the voltage induced in the conductive fluid can be measured by an electrode arrangement of an electromagnetic flowmeter. The electrode arrangement comprises electrodes arranged in a measuring tube of the electromagnetic flowmeter.

[0004] However, during the use of the electromagnetic flowmeter, an oxide layer may be generated on the surface of the electrode of the electromagnetic flowmeter. In the case where solid particles are carried in the flow of the fluid (for example, the fluid is a slurry), these solid particles may scratch the oxide layer and introduce large noise in the original signal. In order to reduce this noise, one method is to make the electrode smaller and polish the electrode to reduce the surface roughness of the electrode. However, this approach may increase the internal resistance at the same time, which is undesirable for low conductivity flow measurement. Another way is to increase the driving frequency, because the noise amplitude decreases with increasing frequency. However, this approach may make the zero point unstable.

[0005] Therefore, it is necessary to propose an electromagnetic flowmeter that overcomes the above-mentioned shortcomings in the art. Summary of the invention

[0006] In order to overcome the shortcomings of the prior art, the present application proposes an electromagnetic flowmeter, wherein a non-metallic layer is applied to the electrode surface of the electrode of the electromagnetic flowmeter. The electrode of the electromagnetic flowmeter with the non-metallic layer added has good conductivity for measurement without increasing the internal resistance too much. Further, the strength of the non-metallic layer is sufficient to protect the electrode surface, thereby providing a stable original signal during grout measurement.

[0007] Embodiments of the present disclosure provide an electromagnetic flowmeter and an associated manufacturing method.

[0008] In a first aspect of the present disclosure, an electromagnetic flowmeter includes: a measuring tube through which a fluid to be measured flows; a magnet coil arranged outside the measuring tube and used to generate a magnetic field; and electrodes arranged on the measuring tube and used to measure a voltage induced by the fluid in the magnetic field, wherein each electrode is coated with a protective layer. Through this feature, the electrodes of the electromagnetic flowmeter have good conductivity for measurement without increasing the internal resistance too much, and the strength of the protective layer is sufficient to protect the electrode surface, thereby providing a stable original signal during grouting measurement.

[0009] In some embodiments, a pair of magnet coils are arranged diametrically opposite to each other. By this feature, a magnetic field can be generated.

[0010] In some embodiments, the electrodes are arranged diametrically opposite each other. By this feature, a voltage can be generated when the fluid moves through the magnetic field.

[0011] In some embodiments, a lining is arranged inside the measuring tube, and the lining is made of an electrically insulating material. Through this feature, the measuring tube is insulated from the fluid.

[0012] In some embodiments, the measuring tube has a through hole and the liner has a through hole, wherein the through hole of the measuring tube and the through hole of the liner are concentric, and the diameter of the through hole of the measuring tube is larger than the diameter of the through hole of the liner. Through this feature, the electrode can be inserted and fixed.

[0013] In some embodiments, each electrode has a head, wherein the head of each electrode is coated with a protective layer. With this feature, the electrode of the electromagnetic flowmeter has good conductivity for measurement without increasing the internal resistance too much, and the strength of the protective layer is sufficient to protect the electrode surface, thereby providing a stable original signal during grouting measurement.

[0014] In some embodiments, each electrode has a body, wherein the body of the electrode extends successively through the through hole of the measuring tube and the through hole of the liner. By this feature, the electrode can be inserted and fixed.

[0015] In some embodiments, an insulating sleeve is provided at the through hole of the measuring tube, wherein a boss is provided at the lower end of the insulating sleeve, and the boss is pressed against the through hole of the measuring tube. Through this feature, the measuring tube can be insulated from parts outside the measuring tube.

[0016] In some embodiments, the insulating sleeve has a through hole including a plurality of sections, the section close to the boss is pressed against the body of the electrode, and the inner diameter of the other sections away from the boss is larger than the inner diameter of the section close to the boss, so as to facilitate installation. By this feature, the electrode can be inserted and fixed.

[0017] In some embodiments, a wire welding pin is provided on the top surface at the upper end of the insulating sleeve, wherein the wire is welded to the wire welding pin to transmit a signal from the electrode. Through this feature, a signal can be transmitted for measurement.

[0018] In some embodiments, a flat washer is provided on the wire welding pin, and a spring washer is provided on the top surface of the flat washer. Through this feature, these parts can be correctly installed.

[0019] In some embodiments, the nut has an internal thread and the internal thread engages with the external thread of the body of the electrode, and a flat washer and a spring washer are positioned between the nut and the wire welding pin for fixing the electrode. Through this feature, these parts can be properly fixed, and the electrode can be inserted and fixed.

[0020] In some embodiments, the fluid is a conductive fluid containing particles. Through this feature, Faraday's law of induction can be applied to the conductive fluid.

[0021] In a second aspect of the present disclosure, a method for applying a protective layer to an electromagnetic flowmeter is provided, the method comprising: mixing a conductive adhesive with an epoxy glue; immersing an electrode of the electromagnetic flowmeter in the mixture of the conductive adhesive and the epoxy glue; and after a predetermined period of time, taking the electrode out of the mixture and leaving it to stand for curing. Through this feature, the protective layer can be applied to the electromagnetic flowmeter so that the electrode of the electromagnetic flowmeter has good conductivity for measurement without increasing the internal resistance too much, and the strength of the protective layer is sufficient to protect the electrode surface, thereby providing a stable original signal during grouting measurement.

[0022] In a third aspect of the present disclosure, a method for applying a protective layer to an electromagnetic flowmeter is provided, the method comprising: applying a conductive adhesive to an electrode of the electromagnetic flowmeter; heating the electrode with the conductive adhesive at a first predetermined temperature for a first predetermined period of time; and heating the electrode with the conductive adhesive at a second predetermined temperature for a second predetermined period of time. Through this feature, the protective layer can be applied to the electromagnetic flowmeter so that the electrode of the electromagnetic flowmeter has good conductivity for measurement without increasing the internal resistance too much, and the strength of the protective layer is sufficient to protect the electrode surface, thereby providing a stable original signal during grouting measurement.

[0023] In some embodiments, the electrode with the conductive adhesive is heated at 100° C. for 30 minutes, and then the electrode with the conductive adhesive is heated at 200° C. for 2 hours. Through this feature, a protective layer is formed after the high temperature is changed to a lower temperature, and the conductive adhesive has the characteristics of conductivity, strong adhesion and firmness, and no additional adhesive is required.

[0024] It should be understood that the invention summary is not intended to identify the key or essential features of the embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of example embodiments of the present disclosure in conjunction with the accompanying drawings, in which like reference numerals generally represent like components throughout the example embodiments of the present disclosure.

[0026] Figure 1 is a schematic diagram of an electromagnetic flowmeter in an XYZ coordinate system according to an embodiment of the present disclosure;

[0027] Figure 2 is a schematic diagram of an electromagnetic flowmeter according to an embodiment of the present disclosure;

[0028] Figure 3 is a cross-sectional view of an electromagnetic flow meter according to an embodiment of the present disclosure;

[0029] Figure 4 is a partially enlarged cross-sectional view of an electromagnetic flowmeter according to an embodiment of the present disclosure;

[0030] Figure 5 is a cross-sectional view of an electrode of an electromagnetic flow meter according to an embodiment of the present disclosure; and

[0031] Figure 6 is a cross-sectional view of an electrode without a protective layer; and

[0032] Figure 7 is a cross-sectional view of an electrode having a protective layer according to an embodiment of the present disclosure.

[0033] The same or similar reference numbers are used throughout the drawings to refer to the same or similar elements. DETAILED DESCRIPTION

[0034] The present disclosure will now be discussed with reference to several example embodiments. It should be understood that these embodiments are discussed only for the purpose of enabling those skilled in the art to better understand and thus implement the present disclosure, and do not imply any limitation on the scope of the subject matter.

[0035] As used herein, the term "including" and its variations should be understood as open-ended terms meaning "including but not limited to". The term "based on" should be understood as "based at least in part on". The terms "one embodiment" and "an embodiment" should be understood as "at least one embodiment". The term "another embodiment" should be understood as "at least one other embodiment". The terms "first", "second", etc. may refer to different or identical objects. Other explicit and implicit definitions may be included below. The definitions of terms are consistent throughout this specification unless the context clearly indicates otherwise.

[0036] The measurements performed by electromagnetic flowmeters are based on Faraday's law of induction. When a conductor moves through a magnetic field, a voltage is induced in the conductor. This principle is applied to a conductive fluid in a measuring tube, through which a magnetic field perpendicular to the flow direction is generated. The voltage induced in the fluid is measured by means of two electrodes positioned diametrically opposite each other, for example. The voltage is proportional to the magnetic induction, the electrode spacing and the average flow velocity. Considering that the magnetic induction and the electrode spacing are constant values, there is a proportionality between the voltage and the average flow velocity. That is, the voltage is linearly proportional to the volume flow rate. The induced voltage is converted by a transmitter into a standardized analog and digital signal to indicate the flow rate. Since the measured voltage obtained in this way is proportional to the average flow velocity of the flowing fluid, the volume flow rate of the fluid can be obtained from this. The mass flow rate of the fluid can be determined by taking into account the density of the flowing fluid.

[0037] In particular, Figure 1 is a schematic diagram of an electromagnetic flowmeter in an XYZ coordinate system. The electromagnetic flowmeter 1 includes an electrode 10, a measuring tube 20, and a magnet coil 30. In an embodiment, a pair of magnet coils 30 are preferably arranged to be diametrically opposite to each other. In an embodiment, there are two magnet coils 30 arranged in a vertical direction, wherein one of the magnet coils 30 is arranged above the measuring tube 20, and the other of the magnet coils 30 is arranged below the measuring tube 20, as shown in FIG. Figure 1 As shown. Figure 1 In the embodiment of the present invention, the magnet coil 30 is used to generate a magnetic field in the vertical direction. In other embodiments, the magnet coil 30 can be arranged in other directions.

[0038] According to Faraday's law of induction, when a conductor moves through a magnetic field, a voltage is induced in the conductor. Figure 1 In the embodiment of the present invention, the fluid flowing through the measuring tube 20 may be a conductive fluid. The fluid may be a slurry or other fluid that may contain particles. The flow direction of the fluid may be along the longitudinal direction, for example, along the direction of the Z axis or in the direction opposite to the Z axis, such as Figure 1The magnetic field generated by the magnet coil 30 is oriented substantially perpendicular to the flow direction of the fluid, for example, along the direction of the Y axis or in the direction opposite to the Y axis, as shown in FIG. Figure 1 As shown. The fluid as a conductor flows along the flow direction and moves through the magnetic field, so a voltage U is induced by the fluid flowing in the magnetic field. At least two electrodes 10 (for example, a pair of electrodes) are inserted on the wall of the measuring tube 20 opposite to each other. The electrodes 10 are used to detect the voltage U, which is induced by the fluid flowing in the magnetic field. In particular, each electrode 10 contacts the flowing fluid through at least one end face, so that the electrode works in the manner of a current electrode.

[0039] Figure 1 Two electrodes 10 are shown, which are preferably arranged diametrically opposite to each other. Preferably, the electrodes 10 are located in a horizontal plane. The induced voltage in the fluid to be measured by the electrodes is proportional to the magnetic induction, the electrode spacing and the average flow velocity v. The electrode spacing can be the same as the diameter D of the measuring tube 20. In view of the fact that the magnetic induction and the electrode spacing are constant values, there is proportionality between the voltage U and the average flow velocity v. That is, the voltage U is linearly proportional to the volume flow rate. Since the voltage obtained in this way is proportional to the average flow velocity v of the flowing fluid, the volume flow rate of the fluid can be obtained from the voltage U. In another embodiment, the mass flow rate of the fluid can also be determined by considering the density of the flowing fluid.

[0040] Figure 2 is a schematic diagram of an electromagnetic flowmeter. Figure 2 In the embodiment of the embodiment, the pair of electrodes 10 are preferably arranged in a vertical direction to be diametrically opposed to each other. In the embodiment shown, the pair of magnet coils 30 are preferably arranged in a horizontal plane to be diametrically opposed to each other.

[0041] Figure 3 A cross-sectional view of an electromagnetic flowmeter is shown. A lining 21 is provided inside the measuring tube 20. The lining 21 may be made of an electrically insulating material, preferably a plastic material. The lining 21 fits tightly with the measuring tube 20 and is used to insulate the measuring tube 20 from the flowing fluid. The electrode 10 is fixed to the wall of the measuring tube 20 to measure the voltage, and the measurement data may be transmitted from the electrode to a processing unit or control unit. The processing unit or control unit may determine the flow rate of the fluid based on the measurement data of the voltage.

[0042] like Figure 3 As shown, there are two electrodes 10 diametrically opposite each other. In other embodiments, more than two electrodes 10 are provided. In other embodiments, these electrodes may not be diametrically opposite each other.

[0043] Figure 4 This is a partial enlarged cross-sectional view of the electromagnetic flowmeter. Figure 4As shown, a through hole is provided on the wall of the measuring tube 20. The lining 21 is also provided with a through hole. The through hole of the measuring tube 20 and the through hole of the lining 21 are concentric. In an embodiment, the diameter of the through hole of the measuring tube 20 is greater than the diameter of the through hole of the lining 21.

[0044] Figure 5 FIG. 2 shows a cross-sectional view of an electrode of an electromagnetic flow meter. Figure 5 As shown, the electrode 10 may include a head 100 and a body 101 , and the body 101 of the electrode 10 extends successively through the through hole of the measuring tube 20 and the through hole of the liner 21 .

[0045] Return to reference Figure 5 , an insulating sleeve 103 is provided at the through hole of the measuring tube 20. A boss is provided at the lower end of the insulating sleeve 103, and the boss is pressed against the through hole of the measuring tube 20. The insulating sleeve 103 has a through hole that may include multiple sections. The section close to the boss is pressed against the body of the electrode to fix the electrode in place. The inner diameter of the other sections away from the boss is larger than the inner diameter of the section close to the boss for easy installation. The body of the electrode also extends through the through hole of the insulating sleeve 103.

[0046] A wire welding pin 104 is provided on the top surface at the upper end of the insulating sleeve 103. A wire is welded to the wire welding pin 104 to transmit signals from the electrode to a processing unit or control unit. These signals can be converted into standardized analog and digital signals to indicate flow. The wire welding pin 104 can have a flat portion with a through hole through which the electrode extends.

[0047] A flat washer 105 is provided on the wire welding pin 104. In an embodiment, the flat washer 105 is provided on a flat portion of the wire welding pin 104. A spring washer 106 is provided on the top surface of the flat washer 105. The spring washer 106 may be in the form of a coil spring. The body of the electrode or a portion of the electrode body may have an external thread. The nut 107 has an internal thread, and the internal thread may engage with the external thread of the electrode body. The flat washer 105 and the spring washer 106 are positioned between the nut 107 and the wire welding pin 104, which helps to fix the electrode.

[0048] refer to Figure 4 and Figure 5, a non-metallic layer 102 is coated on the surface of the head 100 of the electrode 10. When the electrode contacts the fluid to be measured (for example, it is an electrolyte), a passivation reaction occurs, and an oxide layer is generated on the electrode surface to protect the electrode from corrosion. The thickness of this layer is very small, almost nanometer-scale. If there are solid particles such as sand and plastic particles in the fluid, these solid particles may hit and scratch the electrode surface, destroy the oxide layer and cause the original measurement signal to produce a large sharp noise. The oxide layer may be constantly restored and destroyed, and there is always relevant noise during measurement. In other words, in the absence of a non-metallic layer, an oxide layer may be generated on the surface of the electrode during use. And in the case of carrying solid particles in the flow of the fluid (for example, the fluid is a slurry), these solid particles may scratch the oxide layer and introduce a large noise in the original signal. In order to avoid this undesirable situation, the present application adds a non-metallic layer on the surface of the head of the electrode. In the case of being coated with the non-metallic layer, the electrode will have good conductivity for measurement without increasing the internal resistance too much, and the strength of the non-metallic layer is sufficient to protect the electrode surface, thereby providing a stable original signal during grouting measurement.

[0049] like Figure 5 As shown, a non-metallic layer 102 is applied to the head 100 of the electrode 10. The non-metallic layer 102 serves as a protective layer on the surface of the electrode. It is conductive to ensure that the electrode works properly. The protective layer can prevent the electrode from passivation and corrosion. Further, the protective layer is made of a non-metallic material, so there is no oxidation reaction.

[0050] The protective layer can be made of a conductive adhesive and an epoxy adhesive. The conductive adhesive has very good conductivity, but its bonding ability may be poor. Therefore, the conductive adhesive can be mixed with the epoxy adhesive with better bonding ability. In an embodiment, the conductive adhesive is made of epoxy adhesive, conductive particles and additives. The conductive particles can be one of gold powder, silver powder and graphite powder.

[0051] In an embodiment, a conductive adhesive and an epoxy adhesive are mixed together. Then, the head of the electrode is immersed in the mixture of the conductive adhesive and the epoxy adhesive. After a predetermined period of time, the electrode is taken out of the mixture. Then, the electrode is allowed to stand to be cured. After curing, a protective layer is formed by the mixture. Figure 6 A cross-sectional view of an electrode without a protective layer is shown. For example, Figure 6 The electrodes in the mixture are in the state before being immersed in the mixture. Figure 7 A cross-sectional view of an electrode with a protective layer is shown. For example, Figure 7 The electrode in is in a state after a protective layer is formed.

[0052] In some example embodiments, raising the ambient temperature can accelerate this process. After the curing procedure, a strong protective layer will be formed on the electrode surface. In an embodiment, the conductive adhesive can be applied directly to the electrode surface without any additional adhesive. That is, the conductive adhesive is applied to the head of the electrode. For example, the conductive adhesive contains silver powder. First, the electrode head with the conductive adhesive is heated for a first predetermined time period at a first predetermined temperature. For example, the electrode head with the conductive adhesive is heated at 100°C for 30 minutes. Then, the electrode head with the conductive adhesive is heated for a second predetermined time period at a second predetermined temperature. For example, the electrode head with the conductive adhesive is then heated at 200°C for 2 hours. After the high temperature becomes a low temperature, it solidifies and forms a protective layer. In this example, the conductive adhesive has the characteristics of conductivity, strong adhesion and firmness, and does not require an additional adhesive.

[0053] After forming the protective layer, the resistance of the electrode needs to be checked. If the resistance of the electrode with the protective layer is much greater than the resistance of the electrode without the protective layer, the protective layer can be made thinner. However, the protective layer should not be too thin so as not to be easily damaged. Afterwards, the electrode with the protective layer can be installed in the electromagnetic flowmeter. In an embodiment, the oxide layer at the surface of the electrode can be covered with a protective layer so that the electromagnetic flowmeter can provide a stable and strong signal during application to a flowing fluid with solids.

[0054] In such Figures 4 to 6 In the embodiment shown, the head 100 of the electrode 10 has a convex shape, for example a spherical shape. In a variant, the head of the electrode has a concave shape, which can reduce the effects of impact from the flowing fluid.

[0055] Please note that the above description of the electrode only relates to one electrode. The electromagnetic flow meter may have multiple electrodes, and these electrodes may have the same structure as the one electrode described. That is, the above description of one electrode may also apply to the other electrodes.

[0056] It should be understood that the above detailed embodiments of the present disclosure are only used to illustrate or explain the principles of the present disclosure, and do not limit the present disclosure. Therefore, any modifications, equivalent substitutions, and improvements made without departing from the spirit and scope of the present disclosure should be included in the protection scope of the present disclosure. At the same time, the attached claims of the present disclosure are intended to cover all changes and modifications that fall within the scope and limits of the claims, or the equivalents of the scope and limits.

Claims

1. An electromagnetic flowmeter (1), comprising: a measuring tube (20) through which the fluid to be measured flows; a pair of magnet coils (30) arranged outside the measuring tube (20) and configured to generate a magnetic field; as well as at least one pair of electrodes (10) arranged on the measuring tube (20) and configured to measure a voltage induced by the fluid in the magnetic field, Each electrode (10) is coated with a protective layer.

2. The electromagnetic flowmeter (1) according to claim 1, wherein: The pair of magnet coils (30) are arranged diametrically opposite to each other.

3. The electromagnetic flowmeter (1) according to claim 1, wherein: Each pair of electrodes (10) is arranged diametrically opposite to each other.

4. The electromagnetic flow meter (1) according to claim 1, further comprising a lining (21), which is arranged inside the measuring tube (20) and is made of an electrically insulating material.

5. The electromagnetic flowmeter (1) according to claim 4, wherein: The circumferential wall of the measuring tube (20) comprises a first through hole; The liner (21) comprises a second through hole; and The first through hole of the measuring tube (20) and the second through hole of the liner (21) are concentric, and the diameter of the through hole of the measuring tube (20) is greater than the diameter of the through hole of the liner (21).

6. The electromagnetic flowmeter (1) according to claim 1, wherein: Each electrode (10) comprises a head (100), and the head (100) of each electrode (10) is coated with the protective layer.

7. The electromagnetic flowmeter (1) according to claim 5, wherein: Each electrode (10) comprises a body (101), the body (101) of the electrode (10) extending successively through the first through hole of the measuring tube (20) and the second through hole of the liner (21).

8. The electromagnetic flowmeter (1) according to claim 5, wherein: An insulating sleeve (103) is provided at the first through hole of the measuring tube (20); and A boss is provided at the lower end of the insulating sleeve (103), and the boss is pressed against the through hole of the measuring tube (20).

9. The electromagnetic flowmeter (1) according to claim 8, wherein: The insulating sleeve (103) has a through hole including a plurality of sections, the section close to the boss is pressed against the body of the electrode, and the inner diameter of the other sections away from the boss is larger than the inner diameter of the section close to the boss.

10. The electromagnetic flowmeter (1) according to claim 9, wherein: A wire welding pin (104) is provided on the top surface at the upper end of the insulating sleeve (103), wherein a wire is welded to the wire welding pin (104) to transmit a signal from the electrode (10).

11. The electromagnetic flowmeter (1) according to claim 10, wherein: A flat washer (105) is provided on the wire welding pin (104), and a spring washer (106) is provided on the top surface of the flat washer (105).

12. The electromagnetic flowmeter (1) according to claim 11, wherein: The electrode (10) includes a nut (107) having an internal thread and the internal thread is engaged with the external thread of the body of the electrode (10), and the flat washer (105) and the spring washer (106) are positioned between the nut (107) and the wire welding pin (104) for fixing the electrode (10).

13. The electromagnetic flowmeter (1) according to any one of claims 1 to 12, wherein: The fluid is a conductive fluid containing particles.

14. A method for applying a protective layer to an electromagnetic flow meter according to any one of claims 1 to 13, the method comprising: Mix the conductive adhesive and epoxy glue together; Dipping the electrodes of the electromagnetic flowmeter into the mixture of the conductive adhesive and the epoxy glue; as well as After a predetermined period of time, the electrode is removed from the mixture and allowed to stand to cure.

15. A method for applying a protective layer to an electromagnetic flow meter according to any one of claims 1 to 13, the method comprising: applying a conductive adhesive to electrodes of the electromagnetic flow meter; subjecting the electrode with the conductive adhesive to a first predetermined temperature for a first predetermined period of time; as well as The electrode with the conductive adhesive is heated at a second predetermined temperature for a second predetermined period of time.

16. The method of claim 15, wherein: The electrode with the conductive adhesive was heated at 100° C. for 30 minutes, and then the electrode with the conductive adhesive was heated at 200° C. for 2 hours.

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