RU2620780C1 - Method for determining interface position between components of three-component medium in container - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: in the method for determining the interface position between the components of a three-component medium, in which a long line segment is placed vertically in the container with the controlled medium, filled with the medium components according to their location in the container, the medium is probed by the video signals propagating in the long line segment, and the time characteristic of their propagation is calculated, further the electromagnetic oscillations are excited in the long line segment at its resonance frequency, its measurement is carried out, and the position of each interface is determined by the difference values, one of which is proportional to the difference between the value ratio, proportional to the propagation time of the video signals in the presence of the controlled medium in the container at the time of their propagation in the absence of this medium, and one, and another value is proportional to the difference between the value, proportional to the square of the resonant frequency ratio in the absence of the controlled medium to the resonant frequency in the presence of this medium in the container, and one.

EFFECT: simplifying the measurement process and increasing the accuracy.

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Description

The present invention relates to measuring technique and can be used for high-precision determination of the position of the interfaces between the components of a three-component medium located in any container, one component above the other, and forming flat interfaces, in particular air and two immiscible liquids with different densities.

Known methods and devices for measuring the position of the interface between the components of a multicomponent, in particular three-component, medium, the components of which are located in the containing medium of the container vertically one above the other, by radio engineering means, using long line segments (US 3474337 A, 10.21.1969; US 3812422 A, 05.21.1974). In these measurement methods, the position of the interface is judged by the time taken by the electromagnetic video signals to propagate along a long line stretched vertically in a container with a controlled multicomponent medium to inhomogeneities - jumps in the wave (characteristic) resistance at the interfaces of the corresponding components of the medium, and reflection from them.

There is also a technical solution, the technical essence of which is closest to the proposed method and adopted as a prototype (US 3832900 A, 09/03/1974). According to this known method for measuring the position of interfaces between components of a multicomponent medium, a long line segment is arranged vertically in a container with a controlled medium, video pulses are distributed in a long line segment using a pulse generator, video pulses reflected from the interface between the components of the medium are received, and the corresponding reflected video pulses are extracted and judge the position of the boundaries of the section by the time spent by their video pulses to spread ix to the corresponding interfaces and reflection from them.

This method of measurement, despite the use for its implementation of only one segment of a long line, has a number of significant drawbacks. The measurement process here is quite complicated, since the implementation of the method involves the presence of a cumbersome and complex secondary equipment designed to receive video signals reflected from the interface, extracting each of them corresponding to a certain interface, and further functional transformation to obtain the information of interest in a convenient form for registration ( see Fig. 2 in the description of this patent). Moreover, the measurement process can be significantly complicated due to the possible smallness of the amplitudes of the signals reflected from the second (and subsequent) interfaces and weakened due to re-reflections at the interfaces of the overlying components of the medium.

This method is not characterized by high measurement accuracy. When converging interface, there is a mutual influence of informative reflected video signals, leading to distortion of the pulse shape and, therefore, to a decrease in measurement accuracy.

The technical result of the present invention is to simplify the measurement process and increase the accuracy of measurements.

The technical result is achieved by the fact that in the proposed method for determining the position of the interface between the components of the three-component medium in the tank, one component above the other, forming flat horizontal interfaces, in which a length of a long line is filled vertically in the tank with a controlled medium, filled with medium components in accordance with by their location in the capacitance, they probe the medium with video signals propagating in a long line segment, and measure the temporal characteristic of their propagation, additionally excite electromagnetic oscillations at a resonant frequency in a section of a long line, measure it and determine the position of each interface by the difference in values, one of which is proportional to the difference between the ratio of the value proportional to the propagation time of the video signals in the presence of a controlled medium in the capacitor by the time of their propagation in the absence of this medium, and unity, and the other quantity is proportional to the difference between the quantity proportional to the square of the resonance ratio frequency in the absence of a controlled medium to the resonant frequency in the presence of this medium in the capacitance, and unity.

The proposed method is illustrated in FIG. 1, which shows a diagram of a device for implementing the method.

In FIG. 1 shows components 1, 2 and 3, a section of a long line 4, an electronic unit 5.

The method is implemented as follows.

To implement the method for determining the position of the interface between the components of the three-component medium in the tank, here, as in the prototype method, one piece of a long line is used to obtain information. However, now, as informative signals, not video signals reflected from the corresponding interfaces are used, but two different informative parameters - firstly, some temporal characteristic of the propagation of video signals along a long line segment (for example, the period or frequency of the repetition of a sequence of video pulses) and secondly, the resonant frequency of electromagnetic oscillations of a long line segment. The combination of these two dependences on the values of the controlled interface, each of which is expressed by the corresponding equation, allows after solving the system of such equations to obtain the required information.

As for the temporal characteristics of the propagation of video signals, in the proposed method, the informative signals are video signals that have passed through all three components of the medium to the lower end of a long line segment and are reflected from this end to the input of a long line segment. In order for the reflected video signals to have a significant amplitude, a length of a long line can be made open or short-circuited at the lower end.

,

и

соответственно, нижележащей, промежуточной и верхней компонент среды (фиг. 1). На фиг. 1 также изображены отрезок длинной линии 4 длиной

и координаты z₁ и z₂ границ раздела, считая от нижней (оконечной) нагрузки отрезка длинной линии; считается, что нижний конец отрезка длинной линии совмещен с дном емкости.Let us consider how it is necessary to jointly convert in the electronic unit of the device that implements this method the time response of the video signals, characterized, ultimately, by the total time t of their direct (to the lower end of the long line segment) and reverse (to the input of the long line segment) propagation, and resonant (natural) frequency of electromagnetic oscillations of a long line segment. For this, we assume that the components 1, 2, and 3 of the three-component medium contained in the capacitance are dielectric media characterized by relative permittivities

,

and

respectively, the underlying, intermediate and upper components of the medium (Fig. 1). In FIG. 1 also shows a section of a long line 4 long

and the coordinates z ₁ and z ₂ of the interface, counting from the lower (terminal) load of a segment of a long line; it is believed that the lower end of the long line segment is aligned with the bottom of the tank.

Then the total time t of the forward and backward propagation of the video signal along the length of the long line is in this case as follows:

where c is the speed of light.

электромагнитных колебаний основного типа TEM отрезка однородной длинной линии имеем в данном случае следующее выражение (это вытекает, например, из монографии (Викторов В.А., Лункин Б.В., Совлуков А.С. Высокочастотный метод измерения неэлектрических величин. М.: Наука. С. 50-59) с учетом специфики рассматриваемой здесь задачи:For resonant (natural) frequency

In this case, electromagnetic oscillations of the basic type TEM of a segment of a uniform long line have the following expression (this follows, for example, from the monograph (Viktorov V.A., Lunkin B.V., Sovlukov A.S. High-frequency method for measuring non-electric quantities. M: Science. P. 50-59) taking into account the specifics of the problem considered here:

- начальное (при отсутствии в емкости всех трех компонент среды, образующих границы раздела, то есть в отрезке длинной линии с воздушным заполнением) значение резонансной частоты

;Where

- the initial (in the absence in the capacitance of all three components of the medium forming the interface, that is, in the segment of a long line with air filling), the value of the resonant frequency

;

- напряжение в точке с координатой ξ отрезка линии, возбуждаемого на резонансной частоте

; l - длина отрезка длинной линии.

- voltage at a point with coordinate ξ of the line segment excited at the resonant frequency

; l is the length of a segment of a long line.

Relations (1) and (2) will be considered as a system of equations for unknown z ₁ and z ₂ . The value of U (ξ) in (2) depends on the design features of the length of the long line, on the load elements and can be selected in the desired way. From the point of view of simplicity of the function in (2) and expediency, it is most simple to solve the system of equations (1) and (2) that the function U (ξ) can be made constant: U (ξ) ≡const, which corresponds to the uniform nature of the distribution of electromagnetic field energy along the segment long line. Such a distribution can be created, for example, by making a long line segment open at the lower end and connecting an inductive resistance of a sufficiently large value to its input.

In view of the above, relation (2) takes in this case the following form:

Equations (1) and (3) after the transformations can be written, respectively, as follows:

- начальное (при отсутствии в емкости всех трех компонент среды, образующих границы раздела, то есть в отрезке длинной линии с воздушным заполнением) значение времени t.In the formula (4)

- the initial (in the absence of the capacity of all three components of the medium forming the interface, that is, in a segment of a long line with air filling), the value of time t.

Considering equations (4) and (5) as a system of equations for z ₁ and z ₂ and solving it, we obtain

These solutions can also be written as follows:

In these formulas, the following notation is introduced for the constants k ₁ , k ₂ , k ₃ , k ₄ , m, n and Δ - values that depend on the values of the dielectric constant of the components of the medium, which are considered known (reference values or values measured before measurement z ₁ and z ₂ ):

электромагнитных колебаний основного типа TEM отрезка длинной линии и время t распространения вдоль него электромагнитного видеосигнала и преобразовав эти измеренные величины в электронном блоке устройства, реализующего данный способ, согласно соотношениям (8) и (9), получим в явном виде информацию о координатах z₁ и z₂ границ раздела компонент трехкомпонентной среды. Как видно из (8) и (9), эта информация получается в линейном виде, что практически является важным и устраняет необходимость применения специальных линеаризаторов выходных характеристик.Thus, by measuring the resonant frequency

electromagnetic oscillations of the basic type TEM of a long line segment and the propagation time t of the electromagnetic video signal along it and converting these measured values in the electronic unit of the device that implements this method, according to relations (8) and (9), we obtain explicit information on the coordinates z ₁ and z ₂ interfaces of a component of a three-component medium. As can be seen from (8) and (9), this information is obtained in a linear form, which is practically important and eliminates the need to use special linearizers of output characteristics.

и время t можно с высокой точностью, то также будем с высокой точностью получать информацию о координатах z₁ и z₂. При этом два режима функционирования отрезка длинной линии, а именно режим возбуждения в нем электромагнитных колебаний и измерения резонансной частоты

и режим распространения в нем видеосигналов и измерения времени t этого распространения, являются независимыми, в то время как в способе-прототипе взаимное влияние отражаемых от границ раздела видеосигналов приводит к снижению точности измерения.Because, as experience shows, measure the resonant frequency

and time t is possible with high accuracy, then we will also receive with high accuracy information about the coordinates z ₁ and z ₂ . In this case, two modes of functioning of a long line segment, namely, the mode of excitation of electromagnetic waves in it and measuring the resonant frequency

and the distribution mode of the video signals in it and measuring the time t of this distribution are independent, while in the prototype method, the mutual influence of the video signals reflected from the interface leads to a decrease in the measurement accuracy.

(в первом режиме), обеспечение распространения в нем видеосигналов и измерения времени t этого распространения (во втором режиме) и последующее совместное преобразование

и t согласно полученным соотношениям для определения координат z₁ и z₂ границ раздела компонент трехкомпонентной среды. Для упрощения вида функций

и t для их совместного преобразования к верхнему концу отрезка длинной линии также может быть подключено индуктивное сопротивление (для обеспечения равномерного распределения энергии электромагнитного поля вдоль отрезка длинной линии, выполняемого в этом случае короткозамкнутым на нижнем конце).In FIG. 1 schematically shows a functional diagram of a device for implementing this method. Here, in a container containing a three-component medium with components 1, 2 and 3, a vertical segment of a long, in particular coaxial, long line 4 is placed vertically. An electronic unit 5 is connected to its upper end, in which all operations necessary for the implementation of this method are performed: alternating the operation of a long line segment as a resonator with a resonant frequency measurement

(in the first mode), ensuring the propagation of video signals in it and measuring the time t of this distribution (in the second mode) and the subsequent joint conversion

and t according to the obtained relations for determining the coordinates z ₁ and z ₂ of the interface of the components of the three-component medium. To simplify the look of functions

and t, for their joint conversion, an inductive resistance can also be connected to the upper end of the long line segment (to ensure uniform distribution of the electromagnetic field energy along the long line segment, which in this case is made short-circuited at the lower end).

и

компонент среды в приведенных выше соотношениях следует заменить их эффективными значениями ε_эфф1, ε_эфф2 и ε_эфф3 двухслойных диэлектриков (контролируемой компоненты и диэлектрической оболочки проводника отрезка длинной линии), соответственно, определяемыми совокупностью электрофизических параметров контролируемой среды и параметрами отрезка длинной линии.Above, a consideration was given to this method in the presence of a medium in the tank, all of whose components are dielectrics. However, this method is applicable without any change in its essence and for media with components having arbitrary electrophysical parameters (dielectric constant, electrical conductivity). To control such media, it is sufficient to cover at least one of the conductors of the long line segment with a dielectric sheath of the corresponding thickness and material, in which both the amplitude of the reflected video signals and the Q factor of the long line segment as the resonator are sufficient to record the value (V. Viktorov , Lunkin B.V., Sovlukov A.S. High-frequency method for measuring non-electric quantities (Moscow: Nauka, pp. 125-131). Dielectric constant

and

the medium components in the above ratios should be replaced by the effective values ε _eff1 , ε _eff2 and ε _{eff3 of} two-layer dielectrics (of the controlled component and the dielectric shell of the conductor of the long line segment), respectively, determined by the combination of the electrophysical parameters of the controlled medium and the parameters of the long line segment.

Тогда соотношения (6) и (7) записываются так:In the most common problem, the uppermost component of the ternary medium is air. Moreover, in the above formulas should be written

Then relations (6) and (7) are written as follows:

and, accordingly, in formulas (8) and (9), the constants have the following meanings:

k₃=-(ε₁-ε₂);

m=1; n=1;

k ₁ = ε ₂ -1;

k ₃ = - (ε ₁ -ε ₂ );

m is 1; n is 1;

и

компонент среды использовать значения ε_эфф2 и ε_эфф3. В этом случае возможно измерение положения границ раздела воздуха и нижерасположенных компонент с произвольными электрофизическими параметрами.When monitoring three-component media in which the upper medium has air, and at least one of the other components is not a good dielectric, one should use, as noted above, a segment of a long line with a dielectric coating of at least one of its conductors in contact with Wednesday. Moreover, in relations (6) and (7). (8) and (9) follows instead

and

component of the medium to use the values of ε _eff2 and ε _eff3 . In this case, it is possible to measure the position of the air interface and downstream components with arbitrary electrophysical parameters.

Thus, this method allows with high accuracy the position of the interface between the components of the three-component medium in the tank. This method is quite simple to implement, which is feasible on the basis of one segment of a long line.

Claims (1)

A method for determining the position of the interface between the components of a three-component medium in the vessel, one component above the other, forming flat horizontal interface, in which a length of a long line is vertically placed in the vessel with a controlled medium, filled with the medium components in accordance with their location in the vessel, the medium is probed with video signals propagating in a segment of a long line, and measure the temporal characteristic of their propagation, characterized in that it is additionally excited in the segment for of a different line, electromagnetic oscillations at its resonant frequency, measure it and the position of each interface is determined by the difference of values, one of which is proportional to the difference between the ratio of the value proportional to the propagation time of the video signals in the presence of a controlled medium in the capacitance to the time of their propagation in the absence of this medium, and unity, and the other value is proportional to the difference between the value proportional to the square of the ratio of the resonant frequency in the absence of medium to the resonant frequency in the presence of this medium in the capacitance, and unity.

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