RU142932U1 - MAGNETOSTRICTIONAL LEVEL METER - Google Patents

Abstract

A magnetostrictive level gauge, characterized in that it includes an antenna, a digital circuit for storing measurement results with a radio modem, an autonomous power supply, a unit for calculating the interval of time that ultrasonic vibrations travel from the surface — the interface between the liquid fractions and the bottom of the tank, a piezoelectric receiver, and a sensitive element placed in a magnetically permeable tube sound duct made of magnetostrictive material, an autonomous measuring module located at a known distance from the bottom of the tank, at least at least one float placed around the tube with the possibility of moving along it, moreover, active autonomous modules with measuring circuits, sound coil excitation coils and ring magnets with a radially oriented magnetic field are placed in the floats, the antenna located on the outside of the tank and the upper part of the cylindrical casing separated by a temperature barrier from the main part of the body of the level gauge with the electronic part located inside it.

Description

The claimed technical solution relates to measuring equipment and can be used to measure the liquid level mainly in tanks.

A device for measuring the level of a liquid using ultrasonic waves for its operation is known. The device comprises a level gauge tube, a special sound duct in the form of a metal core, on which the primary winding of a linear transformer is located, an electro-acoustic transducer loaded on the sound duct, and also a float covering the level gauge tube. The block of secondary electronic equipment includes a pulse generator, a pulse shaper of reflected signals, a logic block and other elements, the content of which depends on the measurement scheme of the time interval [O. Babikov Ultrasonic monitoring devices. - L .: Engineering, Leningrad Branch, 1985, p. 117. A.S. USSR No. 620828, cl. G01F 23/28, publ. 1978].

The disadvantages of this device for measuring the liquid level are the low accuracy when measuring large levels, the appearance of additional errors when changing over a wide range of ambient temperatures, the inability to measure more than one level, which is especially true for liquids consisting of fractions.

A known ultrasonic level gauge containing a rectilinear magnetostrictive sound pipe, signal electro-acoustic transducer, a float element with a polarizer, a wave reflector, a recording amplifier, a reading amplifier, a coding and computing unit. The coding and computing unit is connected to the sound pipe through a recording amplifier. The other output of the coding and computing unit is connected through a read amplifier to the terminals of the signal electro-acoustic transducer. The signal electro-acoustic transducer is fixed at a reference distance from the end of the sound duct and is connected to the terminals of the reading amplifier. At the other end of the sound duct, a wave reflector is rigidly fixed. A float element with a polarizer is placed between the signal electro-acoustic transducer and the wave reflector [RF Patent No. 2213940, cl. G01F 23/28, G01F 23/30, publ. 2002].

The disadvantages of this device are the large supply voltages (necessary for the formation of an ultrasonic wave by an electro-acoustic transducer, especially with a large length of the sound duct, which makes it difficult to ensure intrinsic safety), the appearance of an additional error when the ambient temperature changes over a wide range, and the inability to measure several levels, which is typical for liquids, consisting of fractions.

Known float level gauge containing an electrically conductive sound pipe, a processing unit, a float mounted on the sound pipe with the ability to move along it, and a conductive element. In addition, the level gauge contains an alternating current generator, an acoustic transducer connected to the upper end of the sound pipe, a discriminator-shaper, an intermediate transformer and the float contains an electric pulse generator, a rectifier located concentrically with the hole of the float, a toroidal transformer and a coil excitation connected to an electric pulse generator [RF patent No. 2463566, class. G01F 23/28, publ. 2006].

The disadvantages of this level gauge are the inability to measure several levels, which is typical for liquids consisting of fractions, the appearance of an additional error when the temperature of the environment changes over a wide range.

Of the known technical solutions, the closest in purpose and technical essence to the claimed one is a magnetostrictive level gauge containing a sensitive element with a sound duct made of magnetostrictive material placed in a magnetically permeable tube, an autonomous measuring module located at a known distance from the bottom of the tank, a piezoelectric receiver, and an ultrasonic transit time interval calculation unit fluctuations from the surface (interface of fractions) of the liquid to the bottom of the tank, at least one float ok, and in the floats there are active autonomous modules that measure the temperature and pressure of the liquid at the location, with measuring circuits under the control of microprocessors, sound field excitation coils and magnetic blocks of n permanent magnets (ring magnets with a radially oriented magnetic field), where n = 1 , 2 ... i, placed around the tube with the possibility of moving along it, and also additionally contains a "Radomsky anchor", which is a rack with a heavier base, three pointed cones E and sealed volume at the top for placing a standalone module. In addition, the level gauge contains an autonomous power source, a digital circuit for storing measurement results, a radio modem and an antenna [RF Patent for Utility Model No. 134317, cl. G01F 23/28, priority date 04.24.2013, publ. November 10, 2013, Bull. No. 31].

The disadvantage of this magnetostrictive level gauge is the appearance of an additional error when the ambient temperature changes over a wide range.

The problem to which the claimed technical solution is directed is to create a magnetostrictive level gauge having an expanded operating range of the ambient temperature by placing the electronics in a volume with a smaller range of temperature changes.

The task is achieved due to the fact that the magnetostrictive level gauge contains a sensitive element with a sound guide made of magnetostrictive material placed in a magnetically permeable tube, an autonomous power supply, a digital circuit for storing the measurement results, a radio modem and an antenna, an active autonomous module located at a known distance from the bottom of the tank, a piezo receiver , unit for calculating the time interval for the passage of ultrasonic vibrations from the surface (interface of fractions) of the liquid to the bottom of the tank at least one float, and active autonomous modules are placed in the floats that measure the temperature and pressure of the liquid at the point of location, with measuring circuits controlled by microprocessors, sound field excitation coils and ring magnets with a radially oriented magnetic field, and also contains a Radomsky anchor ", Which is a rack with a heavier base, three pointed conical supports and a sealed volume in the upper part to accommodate an autonomous module. Moreover, the antenna, located in a cylindrical casing with a radiolucent dome in the upper part and the upper part of the cylindrical casing, is separated from the main part of the body of the level gauge by a temperature barrier.

The technical result provided by the given set of features is to expand the range of operating temperatures of the environment due to the placement of electronics in a volume with a smaller range of temperature changes in the environment, and the installation of a temperature barrier.

The essence of the proposed technical solution is illustrated by graphic materials:

- in FIG. 1 shows a diagram of the implementation of a magnetostrictive level gauge;

- in FIG. 2 shows a functional diagram of an active autonomous module with measuring circuits, a microprocessor, and a sound duct excitation coil;

Magnetostrictive level gauge (Fig. 1) consists of a piezoelectric receiver 2, a sensitive element consisting of a sound pipe 3 in the form of a wire of magnetostrictive material, placed in a magnetically permeable sheath 4 and not fixed in the lower part. A float (s) 6 is placed (placed) on the magnetically permeable shell 4 and can be moved along it (and thus along the sensing element), a sound duct excitation coil, an autonomous module under the control of microprocessor 5, and ring magnets 7 with a radially oriented magnetic field are installed inside the float .

The lower part of the magnetically permeable shell 4 ends with a sealing end device 12, to which the load 13 is attached using a stud 14.

The lower part of the magnetically permeable shell 4 with the end device 12 and the load 13 is included in the design of the "Radomsky anchor" (rack 11 with a weighted base, three pointed conical supports and fixed

 in the upper part of the rack a sealed volume 9 with an autonomous module 8 and a magnetic unit 10).

A block for determining the time interval 15 is connected to the output of the piezoelectric receiver 2, to which, in turn, a block for determining the level with a radio modem is connected 17. A block for determining the time interval 15 and a block for determining the level with a radio modem 17 are connected to an autonomous power source 16.

A piezoelectric receiver 2, a time interval determination unit 15, a level determination unit with a radio modem 17 and an autonomous power source 16 are located in the lower part of the cylindrical body 1. To the upper part of the cylindrical body 1 is connected an adapter sleeve made of a material with a low thermal conductivity (temperature barrier) 18, from above to which is attached a cylindrical casing 19, which, with the help of a collet clamp 22, which allows you to initially put the device in the desired position relative to the armature, is fixed on the cover 21, which turn attached to the top of the container 26. The upper part of the cylindrical housing 19 under the hood 25, radio waves the antenna 24 is attached via the connector 23 and coaxial cable 20 to the power level determination to a wireless modem 17.

The float (floats) 6 floats on the surface of the liquid 27 (at the interface of the liquid fractions).

Stand-alone module 5 (or 8) consists (Fig. 2) of fluid parameters sensors 28 (e.g., temperature sensors) and 29 (e.g., pressure sensors), stand-alone power supply 30, microprocessor 31, energy storage 32, pulse generating circuit 33, and the excitation coil of the sound duct 34 wound on a sleeve into which a magnetically permeable sheath 4 and a sound duct 3 are passed.

The claimed technical solution is illustrated in the interaction between the individual elements in the process.

Stand-alone module 5 (or 8) (Fig. 1), in order to ensure high energy efficiency, most of the time is in the low power consumption mode (sleep mode) and only occasionally activates, forms an encoded pulse train, which, through the excitation coil of the sound duct surrounding the sensor, creates a magnetic field, which, interacting with the radial magnetic field of a ring magnet, causes ultrasonic vibrations in the sound duct propagating through the sound duct x and down, and they are reflected from the bottom end of the acoustic line and return upwards. Thus, at the output of the piezoelectric receiver from each autonomous module, two signals appear, delayed from each other by twice the transit time of ultrasonic vibrations from this autonomous module to the lower end of the sound duct. However, since the sound duct is fixed from above to the container lid, the distance from the lower end of the sound duct to the bottom of the container can change with a change in temperature, which causes a change in the length of the sound pipe, and other factors causing deformation of the roof of the container, so the depth of the immersed part of the sound pipe will also change, which means and the doubled time of passage of ultrasonic vibrations from this autonomous module to the lower end of the sound duct will change. In order to compensate for this error, another stand-alone module 8 is used, rigidly fixed relative to the bottom of the tank.

The calculation of the liquid level is carried out in accordance with the ratios:

h = h _n + h ₁ -h ₂ + h ₃ ,

where h is the distance from the surface of the liquid (the boundary level of the liquid fractions) to the bottom of the tank;

h _n is the distance from the surface of the liquid to the reference point of the measuring float;

h ₁ - the distance from the reference point of the measuring float to the lower end of the sound duct;

h ₂ is the distance from the reference point of the measuring system of the armature to the lower end of the sound duct;

h ₃ - the distance from the reference point of the measuring system of the armature to the bottom of the tank.

The values of h _n and h ₃ are entered into the memory of the meter when it is placed in the tank and calibrated, and h ₁ and h ₂ are calculated based on the measured values of the time intervals t _h1 and t _h2

,

where t _h1 is the ultrasound transit time from the reference point of the measuring float to the lower end of the sound duct;

t _h2 is the ultrasound transit time from the reference point of the measuring system of the armature to the lower end of the sound duct;

V _Sv - the speed of propagation of ultrasound in the sound duct.

The distance h ₃ from the reference point of the measuring system of the armature to the bottom of the tank can be measured with high accuracy during the initial installation of the meter in a tank with liquid as a result of linking a specific level gauge to the tank by measuring the level of the control tape measure relative to the high-altitude stencil according to the passport and calibration table. The value of this quantity is entered into the level determination unit and is used for calculations.

The position of the lower end of the sound duct during operation can change due to changes in the length of the sound duct when the temperature changes, deformation of the roof of the container when the temperature changes, excessive or insufficient pressure, mechanical stresses, however this will not introduce a measurement error, since this error is compensated for by subtraction delays and . Taking into account the coding of the emitted pulses, the output of the piezoelectric receiver is used to separate information from each of the autonomous modules, therefore it is possible to measure several levels (liquid phase boundaries) at the same time, and the encoded information from each of them contains additional liquid parameters at the location of each of the autonomous modules modules (e.g. temperature, pressure).

The operation of the magnetostrictive level gauge can be understood in more detail by considering the interaction between its individual elements (Fig. 2).

The microprocessor 31 of the autonomous module most of the time is in low power mode (sleep mode) and only occasionally activated, reads the parameters measured by sensors 28 and 29 (let's say temperature and pressure), issues a command to store energy to drive 32 from autonomous power source 30 and to the necessary moments starts the pulse shaping circuit 33, which connects

energy accumulator to the excitation coil of the sound guide 34, which generates a pulsed magnetic field, as a result of the interaction of which with the radial magnetic field of the ring magnet (for example, 7) and the magnetostrictive effect, ultrasonic vibrations in the sound guide 3 arise. Ultrasonic vibrations reaching the piezoelectric receiver 2 are transformed due to the piezoelectric effect into voltage pulses that are fed to the input of block 15 for calculating the time interval for the passage of ultrasonic vibrations from the surface (boundary section fractions) liquid to the tank bottom. The value of the time interval from block 15 is supplied to the level determination unit with a radio modem 17, which stores the received information or emits it by antenna 24 connected by connector 23 to coaxial cable 20. Additional liquid parameters transmitted from the sensors can be used in the algorithm for calculating the level determination unit to reduce measurement errors, or transmitted to the consumer.

Closed by the radio-transparent dome 25, the antenna 24 and the upper part of the cylindrical casing 19 are located outside the tank 26, so their temperature corresponds to the ambient temperature. The lower part of the cylindrical casing 19 is located inside the tank and is separated from the main body of the level gauge 1 by a transition sleeve made of a material with a low thermal conductivity (temperature barrier) 18. The temperature inside the tank is associated with the temperature of the liquid 27, is more stable and less dependent on the ambient temperature . Since the electronic part of the level gauge (blocks 15, 16 and 17) is at a more stable temperature, the working range of the external temperature of the level gauge expands, especially towards low temperatures.

Claims (1)

A magnetostrictive level gauge, characterized in that it includes an antenna, a digital circuit for storing measurement results with a radio modem, an autonomous power supply, a unit for calculating the interval of time that ultrasonic vibrations travel from the surface — the interface between the liquid fractions and the bottom of the tank, a piezoelectric receiver, and a sensitive element placed in a magnetically permeable tube sound duct made of magnetostrictive material, an autonomous measuring module located at a known distance from the bottom of the tank, at least at least one float placed around the tube with the possibility of moving along it, moreover, active autonomous modules with measuring circuits, sound coil excitation coils and ring magnets with a radially oriented magnetic field are placed in the floats, the antenna located on the outside of the tank and the upper part of the cylindrical casing separated by a temperature barrier from the main part of the body of the level gauge with the electronic part located inside it.