ELECTROMAGNETIC MULTI-COIL FLOW METER

Description

Background

[0001] The current disclosure relates to flowmeters and more particularly to electromagnetic flowmeters utilized to measure flow of fluids in large pipes in industrial automation. Electromagnetic flowmeters (also referred to as magnetic-inductive flowmeters) measure the velocity and volume of fluid on the basis of electrodynamic induction. A magnetic field is generated by the electromagnetic flowmeter, perpendicular to the flow direction, and accordingly due to the interaction between the magnetic field and the conductive fluid flowing, a voltage perpendicular to the magnetic field and to the flow direction is generated and which is then measured by means of electrodes (known as measuring electrodes). Accordingly, based on the magnitude of the voltage generated, the velocity and volume of the fluid flowing is determined.Prior art

[0002] The international patent application WO 98 / 52001 A1 discloses an electromagnetic flowmeter that comprises two primary electrodes and two secondary electrodes. Both the primary electrodes and the secondary electrodes are arranged in an opposing manner in a single plane in the tube to which the flowmeter is attached. Furthermore, the flowmeter comprises hall sensors which are accommodated near the primary or secondary electrodes respectively.

[0003] Document EP 3 184 969 A1 teaches an electromagnetic flowmeter which comprises four electrodes which are arranged with a right angle between them. The four electrodes form two pairs with each electrode positioned opposite the other electrode of the respective pair. Furthermore, the four electrodes are arranged in a single plane perpendicular to the flow to be measured.Description

[0004] The current disclosure relates to electromagnetic flowmeters. As mentioned previously, electromagnetic flowmeters measure volumetric flow of fluid by applying a magnetic field perpendicular to the flow of the fluid. Accordingly, to generate the magnetic field, the electromagnetic flowmeter includes a plurality of electromagnetic coils which when excited (by applying a current to them), generate the magnetic field. Electromagnetic flowmeters can be used along with pipes of various sizes including large diameter pipes. For large diameter electromagnetic flowmeters, coils have to be of special construction, to ensure the generated magnetic field is spread across the diameter of a measuring section of the electromagnetic flowmeter.

[0005] Often such flowmeters utilize a pair of diamond shaped or rhombus shaped of coils, where each coil covers half of the circumference of a measuring section. Through the rhombus shape, the resultant magnetic field is distributed across the cross section of the flowmeter. However, this requires large coils which are difficult to construct and often involve substantial costs. Additionally, special care has to be taken during the construction of the flowmeter to ensure that the large coils are installed properly on the measuring section of the electromagnetic flowmeter. Accordingly, there is a need for an electromagnetic flowmeter which addresses the issues mentioned above.

[0006] Accordingly, the current disclosure describes an electromagnetic flowmeter capable of being installed on a fluid carrying channel for measuring a volumetric flow of a fluid flowing within the fluid carrying channel. The electromagnetic flowmeter comprises a measuring section configured for flow of the fluid through the electromagnetic flowmeter, a plurality of pairs of coils installed on the circumference of the measuring section, and a transmitter for exciting the plurality pairs of coils by providing one or more driving currents. The plurality of pairs of coils comprises a first pair of coils capable of generating a first magnetic field within the measuring section, and a second pair of coils capable of generating a second magnetic field within the measuring section. The first and second pairs of coils from the plurality of pairs of coils are installed along a first plane of the measuring section, the first plane perpendicular to the flow of the fluid in the measuring section. Accordingly, this ensures that most of generated magnetic fields are all along the same plane and ensure proper measurement of the volumetric flow.

[0007] Accordingly, by using a plurality of pairs of coils, the electromagnetic flowmeter is able to ensure that resultant magnetic fields are spread evenly across the cross section of the measuring section of the electromagnetic flowmeter. Additionally, since each pair of coils is capable of being excited by the transmitter by a corresponding driving current, the interaction between the resultant magnetic fields can be controlled to ensure even distribution in the cross section of the measuring section of the electromagnetic flowmeter. Additionally, since each coil from the pair of coils is required to generate a magnetic field covering only a part of the cross section of the measuring section, the size of the coil is relatively small and therefore the construction effort and the cost of the electromagnetic flowmeter is relatively low. The first magnetic field is distinct from the second magnetic field. In an example, a value of at least one parameter associated with a driving current of the first magnetic field is distinct from a corresponding value of the corresponding at least one parameter associated with a driving current of the second magnetic field. For example, the driving current of the first magnetic field may have a different amplitude or frequency compared to the driving current of the second magnetic field. Accordingly, the first magnetic field is different from the second magnetic field.

[0008] Additionally, a first coil from the first pair of coils acts as one pole of the first magnetic field and a second coil from the first pair of coils acts as the second pole of the first magnetic field. Similarly, first coil from the second pair of coils acts as one pole of the second magnetic field and a second coil from the second pair of coils acts as the second pole of the second magnetic field. Accordingly, a magnetic circuit associated with the first magnetic field is distinct is from a magnetic circuit associated with the second magnetic field. Accordingly, while each magnetic field is distinct from the other magnetic fields, by having a plurality of magnetic fields spread across the majority of the measuring section using smaller coils, the need for large and expensive coils is eliminated.

[0009] According to the invention, the plurality of coils includes a third pair of coils capable of generating a third magnetic field. The third magnetic field is capable of interacting with at least one of the first and the second magnetic field for tuning at least one of the first magnetic field and the second magnetic field. Accordingly, the third pair of coils allow for adjusting the magnetic fields to ensure operation of the electromagnetic flowmeter.

[0010] In an example, the first pair of coils and the second pair of coils are connected in a series connection to each other. In another example, the first pair of coils are connected to the transmitter via a first electrical connection and wherein the second pair of coils are connected to the transmitter via a second electrical connection. In yet another example, the first pair of coils and the second pair of coils are connected in a parallel connection to each other.

[0011] In another aspect, the current disclosure describes a method for measuring a volumetric flow fluid carrying channel for measuring a volumetric flow of a fluid flowing within the fluid carrying channel using an electromagnetic flowmeter. The electromagnetic flowmeter comprises a measuring section configured for flow of the fluid through the electromagnetic flowmeter, a plurality of pairs of coils installed on the circumference of the measuring section, and a transmitter for exciting the plurality of coils by providing a plurality of driving currents. The method comprises providing a first driving current to a first pair of coils for generating a first magnetic field and providing a second driving current to a second pair of coils for generating a second magnetic field. The magnetic circuit associated with the first magnetic field is distinct is from the magnetic circuit associated with the second magnetic field. The method further comprises measuring a voltage generated on a pair of measuring electrodes and determining the volumetric flow rate based on the measured voltage.

[0012] According to the invention, the method further comprises determining a parameter associated with the first magnetic field and providing a third driving current to a third pair of coils based on the determined parameter associated with the first magnetic field, wherein the third pair of coils generate a third magnetic field for tuning the first magnetic field. The advantages of the device apply to the method described herein. These aspects are further described in relation figures 1-4. The following detailed description references the drawings, wherein: Figure 1 is an example electromagnetic flowmeter with a transmitter; Figure 2 is a perspective view of a measuring section with a plurality of pairs of coils of an example electromagnetic flowmeter; Figure 3 is front cross-sectional view of the example electromagnetic flowmeter illustrating the plurality of pairs of coils mounted on the measuring section and the plurality of magnetic fields generated by the plurality of pairs of coils; Figure 4 illustrates two pairs of coils connected in series to the transmitter in section A, connected in parallel in section B and connected two different power sources in section C; and Figure 5 illustrates a method for measuring a volumetric flow fluid carrying channel for measuring a volumetric flow of a fluid flowing within the fluid carrying channel using an electromagnetic flowmeter.

[0013] Figure 1 illustrates an example electromagnetic flowmeter 100 in accordance with the current disclosure. The electromagnetic flowmeter 100 is installed on a pipe (also referred to as fluid carrying channel) in an industrial facility for measuring volumetric flow of a conducting fluid through the pipe. The electromagnetic flowmeter comprises flanges 110 and 130 for connecting to the flowmeter 100 to the ends of two pipes in the industrial facility. Additionally, the electromagnetic flowmeter 100 includes a measuring section 120 which forms the main channel of the electromagnetic flowmeter 100 through which the conducting fluid flows through. Additionally, the electromagnetic flowmeter 100 includes a transmitter and an HMI (human machine interface) module 140. The transmitter and HMI module 140 allows for display of values associated with the electromagnetic flowmeter 100 and configuration of the electromagnetic flowmeter 100. Additionally, the transmitter and HMI module 140 is capable of exciting a plurality of coils (also known as electromagnetic coils) for measurement of the volumetric flow of the fluid through the flowmeter. The measuring section and the coils are further illustrated in figure 2 and explained in the description associated with figure 2.

[0014] Figure 2 shows a perspective internal view of an example measuring section 210. The measuring section 210 which forms the main channel of the electromagnetic flowmeter 100 through which the conducting fluid flows through. The measuring section 210 includes an insulating liner 250 within the inner diameter of the measuring section in order to insulate the fluid from the rest of the measuring section 210. On the outer diameter of the measuring section 210, a plurality of pairs of electromagnetic coils (shown as coils 220, 222, 225, 227) are installed for generating a plurality of magnetic fields within the inner diameter of the measuring section 210. The plurality of pairs of coils (220, 222, 225, 227) are installed along a first plane 290 of the measuring section 210. The first plane 290 is perpendicular to the flow of the fluid in the measuring section 210.The interaction of the magnetic fields and the conducting fluid flowing through the measuring section 210, generates a voltage which is then measured by one or more measuring electrodes. The generated voltage is proportional to the magnetic field and the velocity of the fluid and accordingly, based on the generated voltage, the velocity of the fluid can be determined.

[0015] Relative to diamond coils as known in the state of the art, the relative size of each coil from each pair of coils is small and accordingly each coil does not produce a magnetic field which covers the entire cross section of the measuring section 210. However, this issue is addressed by having a plurality of pairs of coils which generate a plurality of magnetic fields. Accordingly, the plurality of magnetic fields cover the majority of the cross section of the measuring section 210. Therefore, through the usage of the small coils (where each magnetic field generated by a corresponding pair of coils covers only a part of measuring section), the ease of construction of the electromagnetic flowmeter 100 is improved and the overall cost of the electromagnetic flowmeter 100. The electromagnetic coils and the magnetic fields are further explained in relation to in figure 3.

[0016] Figure 3 shows front cross-sectional view of the example measuring section 310 illustrating the plurality of pairs of coils (shown as coils 325 and 327, 315 and 317, 335 and 337, 345 and 347). As mentioned previously, the plurality of pairs of coils (325 & 327, 315 & 317, 335 & 337, 345 & 347) are mounted on the measuring section 310. While in the figure, four pairs of coils (325 & 327, 315 & 317, 335 & 337, 345 & 347) are shown, there may be other combinations involving at least two pairs of coils (such as six pairs of coils, eight pairs of coils, etc.). Each pair of coils generates a corresponding magnetic field upon being excited by a driving current from a transmitter. For example, as shown in the figure, the pair of coils 325 and 327 when excited, generate the magnetic field 330. Similarly, the pair of coils 315 and 317 when excited, generate the magnetic field 320. Similarly, the pairs of coils 335 and 337 when excited, generate the magnetic field 340. Similarly, the pairs of coils 345 and 347 when excited, generate the magnetic field 350. While all the pairs of coils can be excited to generate the corresponding magnetic fields, in an example, a selected number of pairs of coils are excited for generating the corresponding magnetic fields during normal operating condition. For example, during normal operation, only the pairs 315 and 317 (also referred to as first pair of coils), and 335 and 337 (also referred to as second pair of coils) are excited by the transmitter for generating the magnetic fields 320 (also referred to as first magnetic field) and 340 (also referred to as second magnetic field). A first coil from the first pair of coils acts as one pole of the first magnetic field and a second coil from the first pair of coils acts as the second pole of the first magnetic field. Similarly, a first coil from the second pair of coils acts as one pole of the second magnetic field and a second coil from the second pair of coils acts as the second pole of the second magnetic field. The first and the second magnetic fields 320 and 340 interact with the conducting fluid flowing through the measuring section 310 and generate a voltage across two or more measuring electrodes (not shown in the figure) mounted on the measuring section 310. The first and second pairs of coils (315 and 317, 335 and 337) are connected to and excited by the transmitter.

[0017] Figure 4 illustrates a plurality of options in which the first and second pair of coils are connected. In an example, as shown in section A of figure 3, the first and the second pairs of coils (420, 430) are connected in series to each other and to a current source 410 associated with the transmitter. Accordingly, the same driving current is provided to the first and second pairs of coils. In another example, the first and second pairs of coils (420, 430) are connected in parallel to each other, as shown in section B of the figure 4, while being connected to the same current source 410 associated with the transmitter. Accordingly, the driving current is divided between the first pair of coils 420 and the second pair of coils 430. Accordingly, while the magnetic circuits and magnetic poles of the first magnetic field and the second magnetic field are different, the magnitude and characteristics of the first and second magnetic fields may be similar (when connected in series or in parallel). In yet another example, the first and the second pair of coils (420, 430) may be connected to two different current sources (410, 415) associated with the transmitter as shown in section c of the figure 4. For example, the first pair of coils 420 are connected to the current source 410 and the second pair of the coils 430 are connected to the current source 415. Accordingly, the driving current used to excite the first pair of coils 410 may be different from the driving current used to excite the second pairs of coils 430. For example, the frequency or magnitude of the driving current for exciting the first pair of coils 410 may be different from the frequency or magnitude of the driving current for exciting the second pairs of coils 430. Accordingly, the first magnetic field may be different from the second magnetic field.

[0018] As mentioned above, during normal operation, only the first and second pair of coils are active and accordingly, only the first and second magnetic fields are generated within the measuring section. However, when abnormal operation is detected or based on a predefined criterion, one or more additional pairs of coils are excited (in addition to the first and second pairs of coils). For example, when the volume of fluid flowing in the measuring section is too small, additional magnetic fields may be required to ensure accurate measurement. Accordingly, the coils 345 and 347 and coils 325 and 327, may be excited to generate a third and fourth magnetic fields (350 and 330). As mentioned previously, the driving current provided to the coils 345 and 347, and coils 325 and 327 may be similar or different from the currents provided to the first and second pair of coils (315 & 317, 335 & 337). In another example, the additional pairs of coils are excited to interact with the first and the second magnetic fields. For example, the coils 325 and 327 generate the magnetic field 330 which is capable of interacting with the magnetic field 320 (generated by the coils 315 and 317). For example, the magnetic field 330 can tune the magnetic field 320 or amplify the magnetic field 320. Similarly, the coils 345 and 347 generate the magnetic field 350 which is capable of interacting with the magnetic field 340 (generated by the coils 335 and 337). For example, the magnetic field 350 can tune the magnetic field 340 or amplify the magnetic field 340.

[0019] In another aspect, the current invention discloses a method 500 for measuring a volumetric flow fluid carrying channel for measuring a volumetric flow of a fluid flowing within the fluid carrying channel using an electromagnetic flowmeter as described above. This is explained using the example method 500 as shown in figure 5. The method 500 is performed by the electromagnetic flowmeter. At step 510, the transmitter of the electromagnetic flowmeter provides a first driving current to a first pair of coils for generating a first magnetic field. Then at step 520, the transmitter of the electromagnetic flowmeter provides a second driving current to a second pair of coils for generating a second magnetic field. Then, at step 530, the transmitter measures a voltage generated across one or more measuring electrodes due to the interaction of the generated magnetic fields and the conducting fluid. Then based on the voltage, the electromagnetic flowmeter determines the volumetric flow of the fluid. Additionally, as mentioned, a magnetic circuit associated with the first magnetic field is distinct is from a magnetic circuit associated with the second magnetic field.

Claims

1. An electromagnetic flowmeter (100) capable of being installed on a fluid carrying channel for measuring a volumetric flow of a fluid flowing within the fluid carrying channel, the electromagnetic flowmeter (100) comprising: a. a measuring section (310) configured for flow of the fluid through the electromagnetic flowmeter; b. a plurality of pairs of coils (315 and 317, 335 and 337, 325 and 327, 345 and 347) installed on the circumference of the measuring section (310), wherein plurality of pairs of coils (315 and 317, 335 and 337, 325 and 327, 345 and 347) comprises: i. a first pair of coils (315 and 317) capable of generating a first magnetic field (320) within the measuring section (310), and ii. a second pair of coils (335 and 337) capable of generating a second magnetic field (340) within the measuring section (310); and c. a transmitter (140) for exciting the plurality of pairs of coils (315 and 317, 335 and 337, 325 and 327, 345 and 347) by providing one or more driving currents; wherein the first and second pairs of coils (315 and 317, 335 and 337) from the plurality of pairs of coils (315 and 317, 335 and 337, 325 and 327, 345 and 347) are installed along a first plane (290) of the measuring section (210), the first plane (290) perpendicular to the flow of the fluid in the measuring section (310) , characterized in that the plurality of pairs (315 and 317, 335 and 337, 325 and 327, 345 and 347) of coils includes a third pair of coils (325 and 327) capable of generating a third magnetic field (330), wherein the third pair of coils (325 and 327) is excited upon detection of an abnormal operation and wherein the third magnetic field (330) is for tuning at least one of the first magnetic field (320) and the second magnetic field (340).

2. The electromagnetic flowmeter (100) as claimed in claim 1, wherein the transmitter provides a first driving current to the first pair of coils (315 and 317) for generating the first magnetic field (320) and a second driving current to the second pair of coils (335 and 337) for generating the second magnetic field (340).

3. The electromagnetic flowmeter (100) as claimed in claim 1, wherein a diameter of the measuring section is within a range of 1200 millimeters to 3200 millimeters.

4. The electromagnetic flowmeter (100) as claimed in claim 1, wherein the magnetic field strength at the center of the measuring section (310) is between .01 milli Tesla and 10 milli Tesla based on the first and the second magnetic fields (320 and 340).

5. The electromagnetic flowmeter (100) as claimed in claim 1, wherein the first magnetic field (320) is distinct from the second magnetic field (340) and wherein a value of at least one parameter associated with the first driving current is distinct from a corresponding value of the corresponding at least one parameter associated with the second driving current.

6. The electromagnetic flowmeter (100) as claimed in claim 1, wherein a first coil (315) from the first pair of coils (315 and 317) acts as one pole of the first magnetic field (320) and a second coil (317) from the first pair of coils (315 and 317) acts as another pole of the first magnetic field (320).

7. The electromagnetic flowmeter (100) as claimed in claim 1, wherein a magnetic circuit associated with the first magnetic field (320) is distinct is from a magnetic circuit associated with the second magnetic field (340).

8. The electromagnetic flowmeter (100) as claimed in claim 1, wherein the first pair of coils (315 and 317) and the second pair of coils (335 and 337) are connected in a series connection to each other.

9. The electromagnetic flowmeter as claimed in claim 1, wherein the first pair of coils (315 and 317) and the second pair of coils (335 and 337) are connected in a parallel connection to each other.

10. The electromagnetic flowmeter as claimed in claim 1, wherein the first pair of coils (315 and 317) are connected to the transmitter via a first electrical connection and wherein the second pair of coils (335 and 337) are connected to the transmitter via a second electrical connection.

11. A method (500) for measuring a volumetric flow fluid carrying channel for measuring a volumetric flow of a fluid flowing within the fluid carrying channel using an electromagnetic flowmeter (100), the electromagnetic flowmeter (100) comprising a measuring section (310) configured for flow of the fluid through the electromagnetic flowmeter, a plurality of pairs of coils (315 and 317, 335 and 337, 325 and 327, 345 and 347) installed on the circumference of the measuring section (310), and a transmitter (140) for exciting the plurality of pairs of coils (315 and 317, 335 and 337, 325 and 327, 345 and 347) by providing one or more driving currents, the method (500) comprising: a. Providing (510) a first driving current to a first pair of coils (315 and 317) for generating a first magnetic field (320); and b. Providing (520) a second driving current to a second pair of coils (335 and 337) for generating a second magnetic field (340); c. Measuring (530) a voltage on two or more measuring electrodes for determining a volumetric flow of fluid; wherein a magnetic circuit associated with the first magnetic field (320) is distinct is from a magnetic circuit associated with the second magnetic field (340), characterized in that the method (500) further comprises: d. Determining a parameter associated with the first magnetic field (320) and e. Providing a third driving current to a third pair of coils (325 and 327) based on the parameter associated with the first magnetic field (320), wherein the third pair of coils (325 and 327) generates a third magnetic field (330) for tuning the first magnetic field (320).