RU48409U1 - ELECTROMAGNETIC PRIMARY FLOW CONVERTER - Google Patents

Abstract

An electromagnetic flow transducer comprises a portion of a non-magnetic steel pipe coated internally with a layer of glass enamel. In the diametric pipe fittings, two electrodes for signal collection are installed through the pressure glands. On the nozzles perpendicular to the electrodes are fixed plates of magnetically soft material connecting two identical staples of the magnetic circuit. Two bushings are welded to the brackets, pressing the brackets of the excitation coils of the electromagnetic system along their inner diameter. The magnetic circuit is closed with a metal casing. The flow converter improves the accuracy of measurement, has a simple, technological design in the manufacture.

Description

The claimed utility model relates to instrumentation, and in particular to devices for measuring fluid flow by the electromagnetic method.

Known primary flow transducer containing a portion of a pipeline of non-magnetic material with an insulating layer on the inner surface, at least two diametrically opposed electrodes and two excitation coils, as well as a magnetic circuit made of two identical brackets directed towards each other located on the pipeline. Electrodes located on diametrically opposite walls of the pipeline and isolated from them [1]. A disadvantage of the known primary flow transducer is the difficulty of ensuring the tightness of the electrode-lining-pipe connection, capable of withstanding temperature and pressure at the same time, as well as the fact that the lining changes its profile under the influence of temperature and pressure, which leads to a change in the geometry of the flow part of the device and, as a consequence, distortion calibration characteristics of the device, which entails an increase in error.

Also known is a primary electromagnetic flow transducer comprising a pipe segment with an insulated inner surface, a magnetic system, diametrically opposed bosses having holes on the outer surface of the pipeline

with an insulated surface for placement of electrodes, electrodes whose heads are located inside the pipeline, from the outside of the pipeline, the electrodes with insulating gaskets are tightened with nuts. Two annular grooves filled with insulating material are made on the inner surface of the bosses and on the outer surface of the electrodes, the insulated inner surface of the pipeline has flats along the entire length of the pipeline in the places where the electrodes were installed, and the electrodes are flush with the insulated inner surface of the pipeline [2]. A disadvantage of the known electromagnetic primary flow transducer is the difficulty of applying an insulating layer, as well as the fact that with the applied magnetic system it is impossible to obtain the necessary optimal distribution of the magnetic field for all sizes of sensors.

The technical result provided by the utility model is to increase the accuracy and reliability, simplify the design and improve manufacturability.

This result is achieved by the fact that the electromagnetic primary flow transducer contains a pipe segment made of non-magnetic metal with attachment points, the inner surface of which is covered with an insulating material - glass enamel. Two electrodes made of stainless non-magnetic steel or titanium alloy are diametrically located inside the pipe segment, which are designed to pick up the signal. Diametrically opposite to

the outer side of the pipe perpendicular to the axis of the electrodes are two excitation coils designed to create a magnetic field in the flow of the measured fluid. The coils are covered by a magnetic circuit located on the pipeline and made of two identical brackets that cover the excitation coils, the magnetic circuit additionally contains two flat plates connecting the brackets of the magnetic circuit and two bushes that enclose the coils in inner diameter, while the bushes are located in the region of the poles of the magnetic circuit parallel to the placement line electrodes, and the plates are perpendicular to this line at the locations of the electrodes.

A significant difference of the proposed device in comparison with analogues is the use of an insulation coating with a linear expansion coefficient close to the coefficient of linear expansion of the pipe, which eliminates the delamination of the insulation of the flow part and the change in its geometry under the influence of temperature and pressure, and hence the deterioration of the metrological characteristics of the device.

The coating, in its electrical insulation properties, has increased wear resistance, anticorrosion properties and heat resistance. Coating thickness 0.3 mm.

Also simplified the design of the node input electrode; the reliability of mounting the magnetic circuit is improved, the manufacturability is improved, the metrological qualities and metrological reliability are improved due to

the application of the monolithic structure of the structural elements of the magnetic circuit, and the method of attachment.

Figure 1 presents the proposed electromagnetic primary flow sensor. The device comprises: a magnetic circuit, consisting of two identical brackets with welded bushings 1, is mounted on plates 2 to a fitting 3, which is welded to the pipeline 4. At the same time, both halves of the magnetic circuit are a reliable fastening of the coils 5 relative to the pipeline 4, enclosing them in a “lock”, through holes in their center, preventing movement in four possible degrees of freedom (in volume coordinates and rotation relative to the axis of the coils). In the area of fixing the pressure glands 6, the halves of the magnetic circuit form a gap in which the fitting 3 is freely placed, through which the pressure gland 6 is fixed in the pipe 4. The inner surface of the pipe 4 is covered with glass enamel 8.

Thus, due to the bushings, it is possible to bring the magnetic circuit as close as possible to the pipeline, which makes it possible to obtain a more optimal distribution of the magnetic field in the active zone of the channel of the electromagnetic primary flow transducer.

The magnetic circuit of both halves of the magnetic circuit is closed using rectangular plates 2. The plates are made of soft magnetic material, as well as the magnetic circuit, and their section is selected at least section

magnetic circuit. In the magnetic circuit there are round holes that provide free access to pressure glands 6, which is very important for monitoring during operation the insulation resistance of the electrodes relative to the housing. The magnetic system is protected from the environment by a protective casing 7.

Figure 2 presents the bracket of the magnetic circuit 1 with the sleeve 2.

The main advantage of the design is the use of glass enamel coating with a linear expansion coefficient close to the linear expansion coefficient of the pipe material, and in the applied design of the magnetic system, which allows to achieve a more optimal distribution of the magnetic field. The pipe and fitting are made of non-magnetic materials. Only magnetic core and plates are made of ferromagnetic material. An electrically conductive liquid crosses a magnetic field during its movement: In accordance with the law of electromagnetic induction, the current arising in the liquid is perpendicular to the direction of movement of the latter and the direction of the magnetic field.

Induced EMF is proportional to the fluid velocity and is removed from the electrodes.

Using a utility model will improve the accuracy of measurements due to a more optimal distribution of magnetic

fields, increase metrological reliability due to more rigid fixation of the magnetic circuit and coils relative to the channel of the primary transducer, while at the same time simplifying the design and improving manufacturability. Sources of information:

1. Certificate for utility model of the Russian Federation No. 13423, cl. 7 G 01 F 1/58;

2. Certificate for a utility model of the Russian Federation No. 27858, class. 7 G 01 F 1/58;

3. Kremlin P.P. Flowmeters and counters of the amount of substances: Reference: Book 2. / Under the total. ed. E.A. Shornikova. - 5th ed., Revised. and add. - SPb .: Polytechnic, 2004 .-- 412 p.: Ill.

Claims (1)

An electromagnetic primary flow transducer containing a pipe section of non-magnetic metal having an internal electrical insulation coating, two electrodes isolated from the pipe, diametrically installed in the fittings welded to it, and an electromagnetic system located outside the pipe section, consisting of two excitation coils and a coil mounted on the pipe a magnetic circuit closed by a metal casing, characterized in that the magnetic circuit is made in the form of two identical brackets connected by two plates soft-metal astins, fixed perpendicular to the electrodes on the fittings located between the brackets, and two bushings welded to the brackets located in the area of the poles of the magnetic circuit and pressing the excitation coils to the brackets along their inner diameter, while the electrodes are installed in the fittings through the hermetic leads fixed to them, and glass enamel with a linear expansion coefficient close to the linear expansion coefficient of the pipe material was used as an insulating coating.