RU2518470C1 - Method to define level and other parameters of fractionated fluid and magnetostriction level gauge for its implementation - Google Patents

Abstract

FIELD: instrumentation.

SUBSTANCE: method implies formation and delivery of coded electric pulses of specified duration. Afterwards the formed electric pulses are converted into ultrasonic vibrations in an acoustic line by the deformation of the acoustic line, by forming an alternating magnetic flux in an excitation coil winding. The magnetic flux is produced by delivering the formed electric pulses of specified duration to the excitation coil winding by exposing the constant magnetic field to the action of alternating magnetic flux passing through the section of the excitation coil winding and changing the resultant of the magnetic field. Ultrasonic vibrations are converted into electric oscillations by the deformation of a ferroelectric crystal of a piezoelectric receiver under the action of ultrasonic vibrations. Time interval for ultrasonic vibrations passage through the fluid is calculated. The fluid level is defined basing on the known sound speed in the acoustic line and the calculated time interval. The calculated time interval for ultrasonic vibration passage is considered as the sum of a priori measured correction adding value defined by the measured distance from the independent instrumentation module fixed in the known point to the vessel bottom, of the time between the ultrasonic vibration passage from a float to the lower end of the acoustic line, the time of ultrasonic vibration passage from the independent instrumentation module fixed in the known point to the lower end of the acoustic line shall be deducted from the above. The coded signal at the piezoelectric receiver output also contains the data on the fluid parameters and individual number of the measurement point. A magnetostriction level gauge comprises a sensor with a magnetostriction acoustic line put in a magnet permeable pipe, an independent instrumentation module fixed at the known distance from the vessel bottom, a piezoelectric receiver, a unit to calculate the time of ultrasonic vibration passage from the fluid surface (fraction splitting border) to the vessel bottom, at least one float; in the floats there installed are active independent modules with measuring circuits controlled by microprocessors and excitation coils of the acoustic line and magnet units of n constant magnets (annular magnets with radially oriented magnet field), where n =1, 2…i, installed around the pipe and able of moving along it.

EFFECT: improved accuracy of level measurement, compensation of error caused by temperature coefficient of acoustic line expansion, enhanced functionality due to provision for measurement of additional parameters of fluid fractions.

4 cl, 3 dwg

Description

The invention relates to measuring equipment and can be used to measure the level of liquids mainly in tanks.

A known method of measuring the liquid level, based on the generation of ultrasonic vibrations and allows you to measure the time intervals between the appearance of oscillations at the output of the generator and the arrival of the reflected output signal [1, 2]. A liquid level measuring device operating on this principle contains a level tube, a special sound duct in the form of a metal core, on which the primary winding of the linear transformer is located, an electro-acoustic transducer loaded on the sound duct, and also a float covering the level tube [1, 2]. 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 method of measuring the time interval.

The disadvantage of the data of the method and device for measuring the liquid level is the low accuracy when measuring large levels, the inability to measure more than one level, which is especially true for liquids consisting of several fractions.

Known ultrasonic level gauge [3], containing a rectilinear magnetostrictive sound guide, 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. Between the signal electro-acoustic transducer and the wave reflector a float element with a polarizer is placed.

The disadvantages of this device are the large supply voltages necessary for the formation of an ultrasonic wave by an electro-acoustic transducer with a large length of the sound duct, which requires solving the intrinsic safety problem, low measurement accuracy, since the uncertainty of the location of the wave reflector relative to the bottom of the capacitance, the inability to measure several levels, which is typical for liquids consisting of several fractions.

A known method of measuring the liquid level [4], including the formation and supply of an electrical impulse of a given duration, converting the generated electrical impulse to ultrasonic vibrations in a sound pipe, converting ultrasonic vibrations to electrical vibrations on an acoustic transducer, measuring the time interval for the passage of ultrasonic vibrations, determining from a known sound velocity in the sound duct and the measured time interval of the liquid level, and the formation of variable magnesium Nogo flow performed locally at the level of the liquid.

A float level gauge operating on this principle contains an electrically conductive sound duct, a processing unit, a float mounted on the sound duct with the possibility of moving 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 duct, a discriminator — a former, 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 an excitation coil connected to the electric pulse generator .

The disadvantages of this method are the low accuracy of the measurement, since it measures the distance from the top cover of the tank (which may undergo deformation from temperature, overpressure, etc.) to the float, and not the distance from the float to the bottom of the tank, the inability to measure several levels, which typical for liquids consisting of several fractions, the inability to measure additional parameters of the liquid (liquid fractions), such as temperature, pressure, density, etc.

Of the known technical solutions, the closest in purpose and technical essence to the claimed one is the method of measuring the liquid level [5], which includes generating and supplying an electrical pulse of a given duration, converting the generated electrical pulse into ultrasonic vibrations in the sound duct by deforming the sound duct, forming along the entire length of the coil winding excitation variable magnetic flux, and the magnetic flux is formed by feeding the generated electrical pulse back length of time into the winding of the excitation coil, acting on the constant magnetic field flowing through the section of the winding of the excitation coil on a constant magnetic field and changing the resulting magnetic field, converting ultrasonic vibrations into electrical vibrations by deforming the piezoelectric receiver's ferroelectric crystal under the influence of ultrasonic vibrations, measuring the time interval for the passage of ultrasonic vibrations, determination by the known speed of sound in the sound duct and the measured interval webbings liquid level, wherein a time interval of ultrasonic oscillations take the time interval between the time feeding the generated pulse of predetermined duration to winding the excitation coil and the time of formation of electrical oscillations in the piezoelectric.

A magnetostrictive level gauge [5], selected as a prototype, comprising a sensing element with a sound conductor made of magnetostrictive material placed in a dielectric tube, a winding wound on a dielectric tube, at least one float with a magnetic block of n permanent magnets, where n = 1, 2 ... i placed around the insulating shell with the possibility of movement along it, an electric pulse generator, a level determination unit, a piezoelectric receiver, a digital pulse shaper from converted electric their vibrations from the piezoelectric unit determining the time interval between the time of formation of the magnetoelastic effect and the time point of forming the piezoelectric effect. These blocks are connected to each other accordingly.

The claimed invention and the prototype have the following common features: a sensitive element with a sound duct made of magnetostrictive material placed in the tube, at least one float with a magnetic block of n permanent magnets, where n = 1, 2 ... i, placed around the insulating shell with the possibility of movement along it, a level determination unit, a piezoelectric receiver.

The disadvantages of this method are the low accuracy of the measurement (the distance from the top cover of the container, which may undergo deformation from temperature, overpressure, etc., to the float, and not the distance from the float to the bottom of the container, is measured, the change in the length of the sound duct from temperature is not taken into account) the impossibility of measuring at the location of the float additional parameters of the liquid (liquid fractions), such as temperature, pressure, density, etc.

The disadvantage of this magnetostrictive level gauge is also the relatively high cost, complexity and low reliability of the sensitive element (especially with its long length) due to the need to place the winding along its entire length.

The inventive method for determining the level differs from the prototype method in that the formation of an alternating magnetic flux is not carried out along the entire length of the sensing element, but autonomous modules locally located in active floats under the control of microprocessors, additional information about the parameters of the liquid at the location of the floats is transmitted from the floats, not the transit time of ultrasonic vibrations from the surface of the liquid to the piezoelectric receiver (which changes under the influence of various outside these factors - temperature, pressure, etc.), and the time of passage of ultrasonic acoustic line double-length portion of the float until the armature is rigidly fixed relative to the tank bottom, that allows to define precisely the thickness of the liquid layer..

The inventive level gauge differs from the prototype in that there is no need to reel a coil on the sensitive element, which reduces the cost, simplifies the design and improves the reliability of the sensitive element, the unit for determining the time interval between the moment of formation of the magnetoelastic effect and the moment of formation of the piezoelectric effect is replaced by a unit for calculating the time interval of passage of ultrasonic vibrations from surfaces (fractions) of the liquid to the bottom of the tank, active stand-alone modules with measuring mi circuits under the control of microprocessors and excitation coils of the sound duct to each of the floats and an additional active autonomous module located at a known distance from the bottom of the tank.

The present invention is aimed at creating such a method for determining the liquid level and magnetostrictive level gauge for its implementation, which can improve the accuracy of measuring the liquid level (levels of liquid fractions), in particular by compensating for the error associated with the temperature change in the length of the sound duct, and measure additional parameters of the liquid (fractions liquids) such as temperature, pressure, density, etc.

The problem is solved in that in the method of determining the liquid level with a magnetostrictive level gauge containing the formation and supply of an electrical pulse of a given duration, the conversion of the generated electrical pulse into ultrasonic vibrations in the sound duct, produced by the formation of an alternating magnetic flux locally at the level of the measured liquid, the conversion of ultrasonic vibrations on the piezoelectric receiver in electric signal, calculation of the time interval for the passage of ultrasonic vibrations In contrast to the well-known calculation of a known sound velocity in a sound pipe and a measured time interval of a liquid level, the formation of an alternating magnetic flux is carried out by autonomous modules placed in active floats under the control of microprocessors that encode, which allows transmitting additional information about the parameters of the liquid at the location of the floats and distinguish the electrical impulses received on the piezoelectric receiver by belonging to specific floats, while the first, floor received by the piezoelectric receiver from each float, the electric pulse is the reference pulse until the second one appears, which arises from the arrival of an ultrasonic wave propagating downward from the float and reaching the piezoelectric receiver due to reflection from the lower end of the sound duct, and the calculated time interval is obtained by subtracting the time interval from this value formed from a fixed at a known distance to the bottom of the autonomous module and adding to this result the previously measured correcting Additives minutes, allowing through the calculated time interval equal to the transit time of ultrasonic acoustic line double-length portion located below the float, to determine the thickness of the liquid layer, and not the distance from the float to the piezoelectric.

The problem is also solved by the fact that in a magnetostrictive level gauge containing a piezoelectric receiver, a sensitive element with a sound duct made of magnetostrictive material placed in a dielectric tube, at least one float with a magnetic unit of n permanent magnets, where n = 1, 2 ... i (magnets with a radially oriented magnetic field), placed around the insulating shell with the possibility of movement along it, an electric pulse generator, a unit for determining the time interval between the time I magnetoelastic effect and the time of formation of the piezoelectric effect, the level determination unit, in contrast to the known, additionally introduced active autonomous modules with measuring circuits under the control of microprocessors and excitation coils of the sound duct in each of the floats and an additional active autonomous module located at a known distance from the bottom capacity, and instead of a dielectric can be used a tube of any magnetically permeable material.

In addition, according to the invention, the piezoelectric receiver can be connected to a microprocessor, which in turn is connected to an autonomous power source, non-volatile memory and a radio modem.

The invention and the operation of the device is illustrated using graphic materials in which:

- figure 1 presents a functional diagram of the implementation of the proposed method and device for determining the liquid level;

- figure 2 presents the functional diagram of the active autonomous module with measuring circuits under the control of the microprocessor and the excitation coil of the sound pipe;

- figure 3 presents some of the geometric parameters of the level gauge.

The level determination device consists of a sensitive element, which in turn contains a piezoelectric receiver 2 mounted on the upper end of the sound pipe 3 in the form of a wire of magnetostrictive material, not fixed at the bottom placed in a magnetically permeable sheath 4. It is possible to perform a sound pipe in the form of a rod, but in Most designs prefer wire because of its flexibility, which makes it easier to transport a magnetostrictive level gauge. On the magnetically permeable shell 4 a float (floats) 6 is placed (placed) with the possibility of moving along it (and thus along the sensing element), a communication coil, an autonomous module under the control of microprocessor 5 and a magnet block 7 made of a ring magnet with a radially oriented are installed inside the float magnetic field or n permanent magnets, where n = 1, 2 ... i.

The lower part of the magneto-permeable shell 4 ends with a sealing end device 12, to which the load 13 is attached with a pin 14. The lower part of the magneto-permeable shell 4 with the end device 12 and the load 13 is included in the Radomsky anchor structure (stand 11 with a heavier base, three pointed cones and a sealed volume 9 fixed in the upper part of the rack with an autonomous module under the control of the microprocessor 8 and the magnetic unit 10).

To the output of the piezoelectric receiver 2 is attached a block for determining the time interval 16, to which, in turn, is connected to a block for determining the level 15.

The upper part of the magnetically permeable shell 4 with a piezoelectric receiver 2, time interval determination units 16, and a level determination unit 15 is closed by a hermetic casing 1, which, with the help of a collet clamp 17, which allows the device to initially be set in the desired position relative to the armature, is fixed on the cover 18, which in turn attached to the top of the tank 19.

The float (floats) 6 float on the surface of the liquid 20 (at the interface of the liquid fractions).

Stand-alone module 5 (8) consists of liquid parameters sensors 21 and 22, a stand-alone power source 23, a microprocessor 24, an energy storage device 25, a pulse generating circuit 26, an inductor 27 wound on a sleeve into which a magnetically-permeable sheath 4 and a sound duct 3 are passed.

The method can be understood by considering the interaction between the individual elements in the process. To ensure high energy efficiency, the stand-alone module 5 is in a low power consumption mode (sleep mode) and only occasionally are activated, they form coded pulse sequences which, by means of an inductor surrounding the sensing element, cause a magnetic field which, interacting with the magnetic field of a permanent magnet (magnets) ), causes ultrasonic vibrations in the sound pipe that propagate up and down the sound pipe, and below they are reflected on the end of the twin-turbo and also go up. Thus, at the output of the piezoelectric receiver from each autonomous module, two signals are received, delayed from each other by twice the transit time of ultrasonic vibrations from this autonomous module (for example, it is located on the surface of the liquid) 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, because the length of the part of the sound guide below the magnetic system of the autonomous module will change. In order to eliminate 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 made in accordance with the ratio (see figure 3):

, $$h=\left(t_{h_{\mathrm{one}}}-t_{h_2}\right)*V_{s\mathrm{at}}/2+{\mathrm{<figure-callout\; id="3"\; label="h"\; filenames="00000006.png"\; state="\{\{state\}\}">h</figure-callout>}}_3$$

,

Where

h is the distance from the measuring float to the bottom of the tank, m;

h ₁ - distance from the measuring float to the lower end of the sound duct, m;

h ₂ - distance from the measuring system of the armature to the lower end of the sound duct, m;

h ₃ - distance from the measuring system of the armature to the bottom of the tank, m;

V _sv is the speed of sound in the sound duct, m / s.

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

и $$t_{h_2}$$

. С учетом кодирования принимаемых пьезоприемником ультразвуковых колебаний, производится разделение информации от каждого из автономных модулей, поэтому имеется возможность измерения нескольких уровней (границ раздела фаз жидкости) одновременно, причем в кодированной информации от каждого из них содержатся дополнительные параметры жидкости в точке расположения каждого из автономных модулей.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 tank capacity when the temperature, pressure, and mechanical deformations change, but this will not introduce a measurement error, since the error due to this will be compensated for subtracting delays $$t_{h_{\mathrm{one}}}$$

and $${\mathrm{<figure-callout\; id="2"\; label="t\; h"\; filenames="00000006.png"\; state="\{\{state\}\}">t\; </figure-callout>}}_{h_{}}$$

. Taking into account the coding of ultrasonic vibrations received by the piezoelectric receiver, information is separated 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 .

The operation of the level gauge can be understood by considering the interaction between its individual elements.

The microprocessor 24 of the stand-alone module is in low power mode (sleep mode) and only occasionally activates, reads the parameters measured by the sensors 21 and 22 (let's say temperature and pressure), issues a command to store energy to drive 25 from the stand-alone power source 23, and starts the circuit at necessary times the formation of transmission pulses 26, which connects the energy storage to the inductance coil 27, which forms a magnetic field, as a result of the interaction of which with a magnetic field of a constant oppression (for example, 7) and the magnetostrictive effect, ultrasonic vibrations occur in the sound duct. Ultrasonic vibrations reaching the piezoelectric receiver 2, due to the piezoelectric effect, cause voltage pulses at the output of the latter, which are fed to the input of the unit for calculating the time interval of ultrasonic vibrations from the surface (interface of the fractions) of the liquid to the bottom of the tank 16, which calculates this time interval and delivers it to the level determination unit 15, the results of which can be displayed on an indicator device (for example, a digital type), or transferred for storage and display to the shipper. Additional liquid parameters transmitted from the sensors can be used in the algorithm for calculating the level determination unit, or transmitted to the consumer.

The technical result consists in increasing the accuracy of measuring the level (interfaces of fractions) by directly measuring the depth of the liquid, and not the distance from the surface of the liquid to the top cover of the installation nozzle of the tank, which changes its configuration under the influence of various factors (temperature, pressure, etc.), compensation for errors caused by the temperature coefficient of expansion of the sound duct. Functionality expanded by measuring additional parameters of liquid fractions (temperature, pressure, density, etc.).

Information sources

1. Babikov O.I. Ultrasonic monitoring devices. - L .: Engineering, Leningrad Branch, 1985, p. 117.

2. USSR copyright certificate No. 620828, cl. G01F 23/28, 1978.

3. RF patent No. 2213940, cl. G01F 23/28, G01F 23/30, 2002.

4. RF patent No. 2463566, cl. G01F 23/28, 2006.

5. RF patent No. 2222786, cl. G01F 23/28, 2003 - prototype.

Claims (4)

1. A method for determining the level and other parameters of a fractionated liquid, including generating and supplying an electric pulse of a given duration, converting the generated electric pulse to ultrasonic vibrations in the sound pipe, produced by forming an alternating magnetic flux locally at the level of the measured liquid, converting ultrasonic vibrations on the piezoelectric receiver into an electric signal, calculation of the time interval for the passage of ultrasonic vibrations, calculation by known velocity the sound in the sound pipe and the measured time interval of the liquid level, characterized in that the formation of an alternating magnetic flux is carried out by autonomous modules placed in active floats under the control of microprocessors that encode, which allows transmitting additional information about the parameters of the liquid at the location of the floats and distinguishing between the electrical ones obtained on the piezoelectric receiver pulses by belonging to specific floats, while the first received by the piezoelectric receiver from each melting, an electrical impulse is the impulse of the origin to the second, which arises from the arrival of an ultrasonic wave propagating down from the float and reaching the piezoelectric receiver due to reflection from the lower end of the sound duct, and the calculated time interval is obtained by subtracting from this value the time interval formed from the fixed at a known distance to the bottom of the same autonomous module, and adding to this result a pre-measured corrective additive, which allows Using the calculated time interval equal to the ultrasonic transit time of the double length of the part of the sound pipe below the float, determine the thickness of the liquid layer and not the distance from the float to the acoustic transducer, and compensate for errors caused by the temperature coefficient of expansion of the sound pipe. 2. A magnetostrictive level gauge containing a piezoelectric receiver, a sensing element with a sound guide made of magnetostrictive material placed in a magnetically permeable tube, at least one float with a magnetic block 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, an electric pulse generator, a unit for determining the time interval between the time of formation of the magnetoelastic effect and the time the formation of the piezoelectric effect, a level determination unit, characterized in that active autonomous modules with measuring circuits under the control of microprocessors and excitation coils of the sound duct into each of the floats and an additional active autonomous module located at a known distance from the bottom of the tank are introduced into it. 3. The magnetostrictive level gauge according to claim 2, characterized in that it has an autonomous power source, a digital storage circuit for the measurement results, a radio modem and an antenna. 4. The magnetostrictive level gauge according to claim 2, characterized in that it further comprises 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.

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