WO2012083745A1 - Electromagnetic flow meter sensor capable of detecting magnetic field and magnetic permeability - Google Patents

Abstract

An electromagnetic flow meter sensor capable of detecting a magnetic field and magnetic permeability comprises a flange (11) and a measuring tube (12). The flange (11) is installed at two ends of the measuring tube (12). A reference coil (14) and an excitation coil (13) are fixed on the measuring tube (12). The reference coil (14) and the excitation coil (13) are separately wound and are kept at a certain distance. Among signals of the reference coil (14), a proportion of signals reflecting the main measured flux rises to over four times of that of a conventional reference coil, so that it becomes possible to measure a fluid with variable magnetic permeability, and also the zero stability and the measurement accuracy are also increased.

Description

 Electromagnetic flowmeter sensor capable of detecting magnetic field and magnetic permeability

 The invention belongs to the technical field of measuring flow, and relates to an electromagnetic flowmeter sensor, in particular to an electromagnetic flowmeter sensor capable of detecting a magnetic field and a magnetic permeability. Background technique

 The development history of electromagnetic flowmeters is also a history of the development of excitation methods from the perspective of magnetic fields. From the perspective of how to stabilize and compensate the magnetic field, the excitation method mainly has the following four development stages:

 1. Initially, constant voltage excitation. There are also square waves and sine waves. Because the copper resistance changes with temperature, the excitation current changes, causing the magnetic field to change, affecting the measurement accuracy, and it is basically not used.

2. Later developed into constant current excitation. The electromagnetic flowmeter using constant current excitation needs to detect whether the current changes after using for a period of time. If it changes, it needs to be re-adjusted to the original value, or the measured value is input into the electromagnetic flowmeter for software compensation. Most modern electromagnetic flowmeters use this method. Although this method is suitable for many occasions, in the case where the magnetic permeability changes, such as iron ore pulp, the magnetic circuit is rusted, etc., which affects the measurement accuracy and the long-term stability is not good enough.

3. Current feedback. The measured value of the excitation current is automatically compensated for changes, which avoids the trouble of regular adjustment or compensation of the excitation current, but it cannot be applied to the case where the magnetic permeability changes. The disadvantages are the same as those of the constant current excitation. In addition, due to the commutation of the field current, the current has a strong impact on the field line. When the electromagnetic flowmeter is operated for a long time, the insulation layer will age, and frequent electromagnetic force shock may cause a short circuit between turns. Regardless of relying on constant current to keep magnetic The field is stable, or the current feedback is used to compensate for the change of the magnetic field. Once the inter-turn short circuit occurs, the magnetic field will be weakened, resulting in a small flow measurement.

4. With reference line 圏 (also called reference line 圏), was once mistaken for magnetic field feedback. Careful research has found that the reference 圏 and the excitation line are entangled in the past, and most of the signal is the induced voltage caused by the change of the leakage flux component. The signal component generated by the main measurement flux change is small, so the change of the magnetic field is reflected. Very limited, essentially the excitation voltage feedback. In summary, the existing electromagnetic flowmeter sensor has a measurement value that is not accurate and the performance is unstable in the case of a change in magnetic permeability. Summary of the invention

The technical problem to be solved by the present invention is to provide an electromagnetic flowmeter sensor capable of detecting a magnetic field and a magnetic permeability, and the electromagnetic flowmeter sensor can measure a fluid having a variable magnetic permeability. In order to solve the above technical problems, the present invention adopts the following technical solutions. An electromagnetic flowmeter sensor capable of detecting a magnetic field and a magnetic permeability, comprising a flange and a measuring tube, the flange being mounted at two ends of the measuring tube, wherein the measuring tube is fixed with a reference line 励 and an exciting line 圏The reference line 圏 and the excitation line 圏 are individually wound and spaced apart by a certain distance. As a preferred embodiment of the present invention, the exciting wire is fixed to the outer side wall of the measuring tube, and the reference wire is wound into an elongated shape, and the center axis of the exciting wire is installed in the middle of the exciting wire. As another preferred embodiment of the present invention, the reference line 圏 is adjacent to the outer side wall of the measuring tube, - The test line 圏 is larger than the excitation line 圏, and the excitation line 圏 is surrounded by _ε. According to still another preferred embodiment of the present invention, the outer side wall of the measuring tube is provided with a magnetic circuit board, and both ends of the magnetic circuit board pass through the pole The shoe is fixed to the measuring tube, and the reference wire is wound around the magnetic circuit board. As a further preferred embodiment of the present invention, the outer side wall of the measuring tube is provided with a magnetic circuit board, and both ends of the magnetic circuit board are fixed on the measuring tube through the pole piece, and the excitation wire is fixed on one of the pole pieces. The thread is fixed on the other pole piece. As a further preferred embodiment of the present invention, the reference line 圏 is a line or a plurality of turns connected in series. The invention has the beneficial effects that: the electromagnetic flowmeter sensor of the invention can measure the fluid with variable magnetic permeability, and the proportion of the signal reflecting the main magnetic flux change in the reference coil signal is improved.

More than 4 times, it is basically not affected by the eddy current during AC excitation, thus stabilizing the zero point and improving the measurement accuracy. DRAWINGS

1 is a front view of an electromagnetic flowmeter adopting a center-axis winding method according to Embodiment 1; FIG. 2 is a plan view of an electromagnetic flowmeter adopting a center-axis winding method according to Embodiment 1; FIG. 4 is a plan view of the electromagnetic flowmeter adopting the surrounding winding method according to the second embodiment; FIG. 5 is a top view of the electromagnetic flowmeter adopting the surrounding winding method according to the second embodiment; FIG. 6 is a top view of the electromagnetic flowmeter adopting the rosary winding method according to the third embodiment. FIG. Main component symbol description:

11, flange; 12, measuring tube;

 1 3, excitation line 圏; 14, reference line 圏;

 15, electrode; 21, pole boots;

 22, the excitation line 圏; 23, flange;

 24, measuring tube; 25, reference line 圏;

 26, electrode; 31, pole boots;

 32, excitation line 圏; 33, flange;

 34, measuring tube; 35, reference line 圏;

 36. Magnetic circuit board.

DETAILED DESCRIPTION OF THE INVENTION It is an object of the invention to achieve magnetic field feedback. From the history of the development of electromagnetic flowmeters, it is the inevitable result of the development of electromagnetic flowmeter technology, because only when the magnetic field is kept constant, or when the magnetic field changes, it can compensate in time to break through the limitations of the electromagnetic flowmeter, and is suitable for iron ore pulp. When the magnetic permeability changes, the measurement accuracy of the electromagnetic flowmeter in practical applications can be ensured, and the long-term stability of the electromagnetic flowmeter can be improved. The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings. Embodiment 1

 The embodiment provides an electromagnetic flowmeter sensor capable of detecting a magnetic field and a magnetic permeability, as shown in the figure.

1 and 2, including a flange 1 1 and a measuring tube 12, the flange 11 is mounted at both ends of the measuring tube 12, and the outer side wall of the measuring tube 12 is fixed with a reference line 14 and an exciting line 圏1 3 , the reference line 圏 14 and the excitation wire 圏 13 are individually wound and spaced apart. The reference line 圏 14 is not wound with the excitation line ,13, and is separated from the excitation line by a certain distance according to the assembly space; the reference line 圏14 is not only a certain distance from the flange 11, but also has a certain distance from the electrode 15. . For the large diameter, since the excitation wire itself is already close to the outside of the measuring tube, the reference line can be made elongated, like the center line of the excitation line, installed in the middle of the excitation line, this installation method is called the center axis. The central axis reference line 圏 is suitable for large diameter electromagnetic flowmeters. The reference line 圏 can be one, or two, or several, in series. The reference coil can be wound with an enameled wire, which is low in cost; it is also possible to use single or multiple flexible boards, which is consistent. The number of turns of the reference line 根据 is determined experimentally according to the voltage that the converter circuit can match. Generally, when the rated excitation is performed, the output reference signal strength is about 100 mA. In short, to leave a certain distance, try to avoid the scope of leakage flux. Experiments have shown that the ratio of the signal reflecting the main magnetic flux change in the reference coil signal of the present invention is increased by more than 4 times compared with the conventional reference coil, and is substantially unaffected by the eddy current during AC excitation. This is a qualitative difference. With the traditional reference line 圏, as the aperture of the sensor increases, the phase of the reference signal deviates from the phase of the measured magnetic field by up to 15 degrees due to the influence of the eddy current, resulting in partial orthogonal interference being converted into in-phase interference. By adopting the reference line 本 in the invention, the phase difference between the reference signal and the actual measured magnetic field can be controlled within 1 degree, thereby stabilizing the zero point and improving the measurement accuracy. Embodiment 2

The difference between this embodiment and the first embodiment is shown in FIGS. 3 and 4. The flange 23 is mounted on both ends of the measuring tube 24, and the outer side wall of the measuring tube 24 is fixed with a reference line 25 and a field line 22, and a reference line 圏25 Close to the outer casing of the measuring tube 24, the reference line 圏25 is larger than the exciting line 圏22, and the excitation line 圏22 is enclosed, that is, the surrounding type. This mounting method is suitable for the medium-diameter electromagnetic flowmeter. Excitation line 22 is fixed around the magnetic circuit board, and the magnetic circuit board is fixed to the outer side wall of the measuring tube 24 through the pole piece 21. The electrode is disposed at a distance from the reference line 圏 25 on the outer sidewall of the measuring tube 24.

Embodiment 3

 The difference between this embodiment and the first embodiment is shown in FIGS. 5 and 6. The flange 33 is mounted on both ends of the measuring tube 34, and the outer side wall of the measuring tube 34 is fixed with a reference coil 35 and an exciting coil 32, and the exciting coil 圏32 is fixed around the magnetic circuit board 36, and the magnetic circuit board 36 is fixed to the outer side wall of the measuring tube 34 through the pole piece 31. The electrode is disposed on the outer side wall of the measuring tube 34 at a distance from the exciting coil 32. The reference line 圏 35 is wound around the magnetic circuit board 36, that is, the rosary type, and this mounting method is suitable for a small-diameter electromagnetic magnetic flowmeter. Because the space of the small-caliber electromagnetic flowmeter is narrow, the two methods described in Embodiments 1 and 3 cannot be separated from the excitation line by a large distance, so the reference line can be wound around the magnetic circuit board and close to the electrode. The location, away from the pole boots. The reference line 圏 can be wound by one line or by a series of lines. Embodiment 4

 The difference between this embodiment and the third embodiment is that one of the pole pieces is provided with the excitation wire 圏, and the other of the pole pieces is mounted with the reference wire 圏. This type of mounting is suitable for electromagnetic flowmeters with a particularly small diameter. There are generally two methods for making reference coils, one is to use an enameled wire wound, and the other is to use a flexible circuit board.

For the electromagnetic flowmeter sensor with small diameter, the flexible circuit board fixing method is adopted, which does not increase the cost and has good consistency. For large-diameter electromagnetic flowmeter sensors, such as 2 to 3 meters in diameter, the size of the reference coil is very large, not so large flexible circuit board, if not By using, several flexible circuit boards can be connected in series. Of course, in this case, the use of enamelled wire winding has obvious cost advantages. The enameled wire is a main type of winding wire. It consists of two parts: the conductor and the insulating layer. After the wire is annealed and softened, it is baked and baked.

 There are many ways to fix the reference line, but no matter which method is used, it must be firm and cannot change its shape and position. Otherwise, the measurement accuracy will be affected. One way to compare the cartridges is to attach the reference wire to the catheter with fiberglass tape and clean the surface of the catheter before sticking. For the sake of safety, reinforced with silica gel. The invention has the following advantages:

 1. Since the reference line 圏 signal of the present invention reflects the essential improvement of the composition of the measuring magnetic field, it is possible to realize the true magnetic field feedback of the electromagnetic flowmeter. Experiments have shown that the theoretical and measured values of the equivalent magnetic field of the electromagnetic flowmeter differed little. Since AC excitation is generally used for industrial control, the fluid condition is complicated, and it is not convenient to calibrate all frequencies at the time of calibration. The magnetic field feedback makes the meter coefficients of each frequency almost the same, and the better frequency can be selected according to the site conditions.

 2. It is possible to measure a fluid with a variable magnetic permeability, such as iron ore pulp, which breaks through the forbidden zone of the electromagnetic flowmeter. For iron concentrate slurry, the concentration of radioactive elements is currently measured, which is not only low in accuracy, but also dangerous to maintain and manage due to nuclear radiation, and high in cost. If the effective concentration of iron concentrate is measured by the magnetic permeability method, it is not only safe and convenient, but also the mass flow rate of the iron concentrate can be directly given by the volume flow rate and concentration. The realization of electromagnetic flowmeter, wet grade of iron concentrate slurry and mass flow of iron concentrate is one of the breakthroughs in this field, which will solve the problem that cannot be solved for a long time.

3. Filled a major loophole in the field verification. In the case where the fluid permeability does not change, such as water, the state of the sensor can be diagnosed by calculating the change in magnetic permeability, whether a turn-to-turn short circuit occurs, the magnetic circuit is rusted, etc., and the change of the magnetic field is compensated, in the event of a failure, Reduce measurement error. If a turn-to-turn short circuit occurs, the permeability indication will become smaller, which will help to detect the fault. The relative magnetic permeability detection method is not necessarily implemented online, and can also be used for offline detection. Input the constant sine wave excitation current, measure the reference line 圏 waveform, and calculate the magnetic permeability. If the permeability does not change, the sensor has no associated fault. This off-line method is particularly suitable for constant current square wave excitation electromagnetic flowmeters. The description and application of the present invention are intended to be illustrative, and not intended to limit the scope of the invention. Variations and modifications of the embodiments disclosed herein are possible, and various alternative and equivalent components of the embodiments are well known to those of ordinary skill in the art. It is apparent to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, ratios, and other elements, materials and components without departing from the spirit or essential characteristics of the invention.

Claims

The invention provides an electromagnetic flowmeter sensor capable of detecting a magnetic field and a magnetic permeability, comprising a flange and a measuring tube, the flange being mounted at two ends of the measuring tube, wherein: the measuring tube is fixed with a reference The wire 励 and the excitation wire 圏, the reference wire 圏 and the excitation wire 圏 are separately wound and spaced apart by a certain distance. The electromagnetic flowmeter sensor capable of detecting a magnetic field and a magnetic permeability according to claim 1, wherein: the excitation wire is fixed to an outer side wall of the measuring tube, and the reference wire is wound into an elongated shape. The center shaft of the excitation line 安装 is installed in the middle of the excitation line 。. The electromagnetic flowmeter sensor capable of detecting a magnetic field and a magnetic permeability according to claim 1, wherein: the reference line 圏 is adjacent to an outer side wall of the measuring tube, and the reference line 圏 is larger than the exciting line, and the excitation is performed. The line is surrounded. The electromagnetic flowmeter sensor capable of detecting a magnetic field and a magnetic permeability according to claim 1, wherein: the outer side wall of the measuring tube is provided with a magnetic circuit board, and both ends of the magnetic circuit board are fixed to the measurement by the pole piece. On the tube, the reference line is wound around the magnetic circuit board. The electromagnetic flowmeter sensor capable of detecting a magnetic field and a magnetic permeability according to claim 1, wherein: the outer side wall of the measuring tube is provided with a magnetic circuit board, and both ends of the magnetic circuit board It is fixed to the measuring tube by the pole piece, one of the pole pieces is fixed with the excitation wire 圏, and the other pole piece is fixed with the reference line 圏. The electromagnetic flowmeter sensor capable of detecting a magnetic field and a magnetic permeability according to claim 1, wherein the reference line 圏 is a line or a plurality of turns.