JPH109911A - Electromagnetic flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow the user to easily wash an electrode section without replacement of a process flow medium and without removing a measurement pipe. SOLUTION: The electromagnetic flowmeter where a flow of a flow medium 2 is electrically measured by applying an alternate magnetic field 5 to the conductive flow medium 2 flowing in a measurement pipe 2 almost at a right angle to the flowing direction of the flow medium 2 and detecting an electromotive force induced in the flow medium 2 by means of a couple of electrodes 6 is provided with a voltage application means 8 applying a DC voltage to a couple of the electrodes 6. In the case of washing the electrodes 6, the voltage application means 8 is used to apply a voltage to a couple of the electrodes 6 to supply a current to the flow medium 2 between the electrodes 6 in a state that the flow medium 2 is filled in the measurement tube 1 at least at a level till the flow medium 2 is in contact with a couple of the electrodes 6 and the alternate magnetic field 5 is applied to the flow medium 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic flowmeter for electrically measuring a flow rate of a conductive fluid flowing in a measuring tube, and in particular, without replacing a process fluid and removing a measuring tube. The present invention relates to an electromagnetic flowmeter that can easily clean an electrode portion.

[0002]

2. Description of the Related Art Recently, an electromagnetic flowmeter has been widely used as a means for electrically measuring a flow rate of a fluid. This electromagnetic flowmeter applies an alternating magnetic field to a conductive fluid flowing in a measuring tube in a direction substantially perpendicular to the flow direction of the fluid, and detects an electromotive force induced in the fluid by a pair of electrodes. , And electrically measures the flow rate of the fluid.

[0003] This type of electromagnetic flowmeter has no obstruction in the flow path and no mechanism driving unit, and therefore has a higher efficiency than other flowmeters.
Although it is said that the maintenance property is good, depending on the fluid to be measured, there are not a few substances that cause deposits in the measurement tube.

[0004] In particular, when deposits occur on the electrodes,
It is desirable to periodically clean the electrode part because it may cause output errors and the like.As a method for cleaning the electrode part, conventionally, a cleaning liquid or steam is periodically passed through the measuring tube to clean the electrode part. Alternatively, a method has been adopted in which the detector is removed from the measuring tube to remove the attached matter directly.

However, in such a method, it is necessary to replace the process fluid or to remove the measuring tube to stop the plant. Therefore, depending on the plant, it is very difficult or impossible to perform cleaning. There is also.

[0006]

As described above, in the conventional electromagnetic flow meter, when cleaning the electrode portion,
There was a problem that the process fluid had to be replaced or the measuring tube had to be removed.

An object of the present invention is to provide an electromagnetic flowmeter which can easily clean an electrode portion without replacing a process fluid and without removing a measurement tube.

[0008]

In order to achieve the above object, a conductive fluid flowing through a measuring tube is provided.
In an electromagnetic flowmeter for electrically measuring the flow rate of a fluid by applying an alternating magnetic field in a direction substantially perpendicular to the flow direction of the fluid and detecting an electromotive force induced in the fluid by a pair of electrodes, In the invention corresponding to Item 1, a voltage applying means for applying a DC voltage to the pair of electrode portions is provided, and when the electrode portions are washed, the fluid is filled in the measuring tube to a level at which the fluid comes into contact with at least the pair of electrode portions, and In the state where the alternating magnetic field is applied, a voltage is applied to the pair of electrodes by the voltage applying means, so that a current flows through the fluid between the electrodes.

Therefore, in the electromagnetic flowmeter according to the present invention, a direct current is applied to the pair of electrode portions while an alternating magnetic field is applied to the fluid flowing in the measuring tube substantially perpendicularly to the flow direction. By applying a voltage and applying a current to the fluid between the electrodes, a force acts on the fluid in accordance with Faraday's law of electromagnetic induction. The acting direction of this force is a direction substantially perpendicular to the alternating magnetic field and the electrode axis, that is, the flow path direction, according to Fleming's left hand rule.

[0010] In this case, since the alternating magnetic field is applied as described above, the force acting on the fluid acts alternately in front and back, and the fluid vibrates on the surface of the electrode portion.
Deposits on the electrode part can be removed.

Further, in the invention corresponding to claim 2, when cleaning the electrode portion, a magnetic field generating means for generating a magnetic field having a constant polarity and strength instead of the alternating magnetic field, and applying an alternating voltage to the pair of electrode portions. A voltage applying means for filling the fluid inside the measuring tube to a level at which the fluid comes into contact with at least the pair of electrodes and applying a constant magnetic field when the electrode section is washed. An alternating voltage is applied to the electrodes of the electrodes, and an alternating current is supplied to the fluid between the electrodes.

Therefore, in the electromagnetic flow meter according to the second aspect of the present invention, contrary to the electromagnetic flow meter according to the first aspect of the present invention, the magnetic field has a constant polarity and strength instead of alternating. By alternately changing the voltage applied to the electrode portion, it is possible to remove deposits on the electrode portion in the same manner.

Further, in the invention corresponding to claim 3, a voltage applying means for applying an alternating voltage to the pair of electrode portions in synchronization with an alternating magnetic field is provided, and at the time of cleaning the electrode portions, at least one pair of fluids is contained in the measuring tube. In a state where the liquid is filled to the level of contact with the electrodes and an alternating magnetic field is applied, an alternating voltage is applied to the pair of electrodes by the voltage applying means, and an alternating current is supplied to the fluid between the electrodes. I am trying to do it.

Therefore, in the electromagnetic flowmeter according to the third aspect of the present invention, both the magnetic field and the voltage applied to the electrode portion are alternated, so that the electromagnetic flowmeter according to the first and second aspects of the present invention can be used. Since a stronger detergency can be exerted than in the case of the flow meter, the deposits on the electrode portion can be more reliably removed in the same manner. As described above, the electrode section can be easily cleaned without replacing the process fluid and without removing the measurement tube.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. (First Embodiment) FIG. 1 is a schematic diagram showing a configuration example of an electromagnetic flow meter according to the present embodiment.

In FIG. 1, an electromagnetic flow meter according to the present embodiment is provided with a pair of magnetic poles 3 and a coil 2 in a direction substantially perpendicular to the flow direction of the fluid 2 having conductivity in a measuring tube 1. An alternating magnetic field 5 is applied by an electromagnet consisting of an electromagnet 4, and an electromotive force induced in the fluid 2 is detected by a pair of electrodes 6 provided substantially horizontally facing the tube wall of the measuring tube 1, and the electromagnets are generated from the electrodes 6. Is input to a measurement circuit (not shown) to electrically measure the flow rate of the fluid 2.

Further, a DC power supply 8 is connected to the pair of electrodes 6 via a switch 7. The switch 7 and the DC power supply 8 constitute voltage applying means. Here, the switch 7 is closed periodically, manually, or automatically when the pair of electrodes 6 is washed.

Next, the operation of the electromagnetic flow meter according to this embodiment configured as described above will be described. In FIG. 1, when measuring the flow rate of the fluid 2 flowing in the measurement tube 1, the flow direction of the fluid 2 flowing in the measurement tube 1 is substantially perpendicular to the flow direction.
An alternating magnetic field 5 is applied by an electromagnet including the magnetic pole 3 and the coil 4. Then, the electromotive force induced in the fluid 2 by this is detected by the pair of electrodes 6 provided in the measurement tube 1,
The detection signal is input to a measurement circuit (not shown),
Is electrically measured.

On the other hand, when cleaning the pair of electrodes 6, the fluid 2 is filled in the measuring tube 1 to a level at which the fluid 2 comes into contact with at least the pair of electrodes 6, and the alternating magnetic field 5 is applied. Then, the switch 7 is closed, and a voltage 9 is applied to the pair of electrodes 6 by the DC power supply 8 so that the fluid 2 between the electrodes 6
Is supplied with current.

In this case, a force acts on the fluid 2 in accordance with Faraday's law of electromagnetic induction. The direction of action 10 of this force is substantially perpendicular to the alternating magnetic field 5 and the axis of the electrode 6 according to Fleming's left hand rule, that is, the direction of the flow path.

At this time, since the alternating magnetic field 5 is applied alternately as described above, the force 10 acting on the fluid 2 also acts alternately in the front-rear direction, so that the fluid 2 vibrates on the surface of the electrode 6. Become.

As a result, the surface of the electrode 6 or the measuring tube 1
Deposits on the inner surface can be removed. This makes it possible to easily clean the electrode 6 without replacing the process fluid and without removing the measuring tube 1.

As described above, in the present embodiment, the alternating magnetic field 5 is applied to the conductive fluid 2 flowing in the measurement tube 1 in a direction substantially perpendicular to the flow direction of the fluid 2.
In an electromagnetic flowmeter that electrically measures the flow rate of the fluid 2 by detecting an electromotive force induced therein by a pair of electrodes 6, a direct current that applies a DC voltage to a pair of electrodes 6 via a switch 7 is applied. The switch 7 is provided with a power supply 8 in a state in which the fluid 2 is filled in the measuring tube 1 to a level at which the fluid 2 comes into contact with at least the pair of electrodes 6 and the alternating magnetic field 5 is applied when the electrodes 6 are washed. When closed, a voltage is applied to the pair of electrodes 6 by the DC power supply 8 to supply a current to the fluid 2 between the electrodes 6.

Therefore, a force 10 acting alternately in the front-rear direction acts on the fluid 2, and the fluid 2 vibrates on the surface of the electrode 6, so that the process fluid is not replaced.
Further, the electrode 6 can be easily cleaned without removing the measuring tube 1, so that the maintainability can be further improved.

(Second Embodiment) The electromagnetic flowmeter according to the present embodiment is such that the polarity and strength of the magnetic field applied to the fluid are kept constant and the voltage applied to the electrode 6 is changed.

That is, in the first embodiment shown in FIG. 1, it is possible to generate a force in the fluid 2 by turning on and off the switch 7 while keeping the polarity of the exciting current flowing through the coil 4 constant. However, an alternating voltage whose polarity is inverted may be applied to the electrode 6.

In the electromagnetic flow meter according to the present embodiment as well, the electrode 6 can be easily cleaned without replacing the process fluid and without removing the measuring tube 1, thereby further improving the maintainability. It becomes possible.

(Third Embodiment) In the electromagnetic flowmeter according to the present embodiment, the polarity of the magnetic field applied to the fluid 2 and the polarity of the voltage applied to the electrode 6 are changed synchronously. .

That is, in the first embodiment shown in FIG. 1, if the direction of the magnetic field and the direction of the flow of the fluid 2 are determined, the direction of the current flowing through the fluid 2 is also determined. If a voltage is applied to the electrode 6 so that a current flows in the same direction as the direction of the current, the flow of the fluid 2 is accelerated, and conversely, the current flows in a direction opposite to the direction of the current. When the voltage is applied to the electrode 6 so that the fluid flows, the flow of the fluid 2 is decelerated.

Therefore, for example, by changing the polarity of the voltage applied to the electrode 6 by synchronizing with the polarity of the magnetic field applied in an alternating manner so that acceleration and deceleration occur alternately in the flow of the fluid 2, Since a stronger cleaning power can be exhibited, the electrode 6 can be more strongly cleaned.

In the electromagnetic flow meter according to the present embodiment as well, the electrode 6 can be easily and more powerfully cleaned without replacing the process fluid and without removing the measuring tube 1, thereby improving the maintainability. Can be further improved.

[0032]

As described above, an alternating magnetic field is applied to a conductive fluid flowing in a measuring tube in a direction substantially perpendicular to the flow direction of the fluid, and an electromotive force induced in the fluid is caused by a pair of electromotive forces. In an electromagnetic flowmeter that electrically measures a flow rate of a fluid by detecting with an electrode, first, according to the invention corresponding to claim 1, a voltage application unit that applies a DC voltage to a pair of electrode units is provided, At the time of cleaning the electrode portions, the voltage is applied to the pair of electrode portions by the voltage applying means in a state where the fluid in the measurement tube is filled to a level at which the fluid comes into contact with at least the pair of electrode portions, and an alternating magnetic field is applied. Since an electric current is applied to the fluid between the electrodes, it is possible to provide an electromagnetic flowmeter that can easily clean the electrode portion without replacing the process fluid and without removing the measurement tube.

Further, according to the invention corresponding to claim 2,
At the time of cleaning the electrode portion, a magnetic field generating means for generating a magnetic field having a constant polarity and strength instead of the alternating magnetic field, and a voltage applying means for applying an alternating voltage to a pair of electrode portions, In a state where the fluid in the measuring tube is filled to a level at which the fluid comes in contact with at least the pair of electrodes, and a constant magnetic field is applied, an alternating voltage is applied to the pair of electrodes by the voltage applying means, and each electrode is applied. Since an alternating current is applied to the intervening fluid, it is possible to provide an electromagnetic flowmeter that can easily clean the electrode portion without replacing the process fluid and without removing the measurement tube.

Further, according to the invention corresponding to claim 3, a voltage applying means for applying an alternating voltage to the pair of electrode portions in synchronization with the alternating magnetic field is provided, and at least when the electrode portions are washed, at least fluid is present in the measuring tube. In a state where the liquid is filled to a level at which the pair of electrodes are in contact with each other and an alternating magnetic field is applied, an alternating voltage is applied to the pair of electrodes by the voltage applying means, and an alternating current is applied to the fluid between the electrodes. So that it is energized,
An electromagnetic flowmeter capable of easily and more powerfully cleaning an electrode portion without replacing a process fluid or removing a measurement tube can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of an electromagnetic flow meter according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Measurement tube, 2 ... Fluid, 3 ... Magnetic pole, 4 ... Coil, 5 ... Alternating magnetic field, 6 ... Pair of electrodes, 7 ... Switch, 8 ... DC power supply, 9 ... Voltage application direction, 10 ... Act on fluid 2 Direction of force.

Claims (3)

[Claims] An alternating magnetic field is applied to a conductive fluid flowing in a measuring tube in a direction substantially perpendicular to a flow direction of the fluid, and an electromotive force induced in the fluid is detected by a pair of electrodes. An electromagnetic flowmeter for electrically measuring the flow rate of the fluid, comprising: voltage applying means for applying a DC voltage to the pair of electrode portions; at the time of cleaning the electrode portions, at least the pair of fluids in the measurement tube. With the voltage applied to the pair of electrode portions, the voltage is applied to the pair of electrode portions while the alternating magnetic field is being applied, and a current is applied to the fluid between the electrodes. An electromagnetic flowmeter characterized in that: 2. An alternating magnetic field is applied to a conductive fluid flowing in a measuring tube in a direction substantially perpendicular to the flow direction of the fluid, and an electromotive force induced in the fluid is detected by a pair of electrodes. According to the electromagnetic flowmeter for electrically measuring the flow rate of the fluid, a magnetic field generating means for generating a magnetic field having a constant polarity and strength in place of the alternating magnetic field when cleaning the electrode unit, and the pair of electrode units A voltage applying means for applying an alternating voltage to the electrode portion, and when the electrode portion is washed, the fluid in the measurement tube is filled to a level at which the fluid comes into contact with at least the pair of electrode portions, and the constant magnetic field is applied. An electromagnetic flow meter, wherein an alternating voltage is applied to the pair of electrodes by the voltage applying means in a state where the fluid flows between the electrodes. 3. An alternating magnetic field is applied to a conductive fluid flowing in a measuring tube in a direction substantially perpendicular to a flow direction of the fluid, and an electromotive force induced in the fluid is detected by a pair of electrodes. An electromagnetic flowmeter that electrically measures the flow rate of the fluid, comprising: a voltage application unit that applies an alternating voltage to the pair of electrode units in synchronization with the alternating magnetic field. Applying an alternating voltage to the pair of electrode units by the voltage applying unit while the pipe is filled with a fluid at least to a level at which the fluid contacts the pair of electrode units, and applying the alternating magnetic field, An electromagnetic flowmeter characterized in that an alternating current is applied to the fluid between the electrodes.