RU2173847C1 - Device for determination of density of nonpolar matters in dielectric pipe- lines - Google Patents

Abstract

FIELD: determination of density of nonpolar matters in dielectric pipe-lines. SUBSTANCE: device has a microwave oscillator, the first and second coupling elements, microwave detector, indicator whose output serves as the device output, ring vibrator made in the form of a folded rectangular waveguide diametrically fastened with the open ends on the external surface of the dielectric pipe-line, the output of the microwave oscillator via the first coupling element is connected to the input of the ring vibrator, the output of the ring vibrator via the second coupling element is connected to the input of the microwave detector, whose output is connected to the indicator input. EFFECT: enhanced accuracy of measurement. 1 dwg

Description

 The invention relates to the field of measuring equipment and can be used in process control systems.

 Known radio wave density meters of liquid and granular media, using the resonant properties of long line segments (see V.A. Viktorov et al. "Measuring the density of various media", M: "Energy", 1973, pp. 96-97). In these devices, the main nodes of which are the primary transducer immersed in the measured medium (a long line segment) and an electronic unit, the density is determined from the resonant frequency of the long line segment.

 The disadvantages of these developments should be considered as contact with the measured medium of the sensitive element and a change in the parameters of its design due to temperature influences, leading to errors.

 The closest technical solution to the proposed one is the microwave device adopted by the author for the prototype (see V. A. Viktorov et al. "Radio wave measurements of technological process parameters", Moscow: Energoizdat, 1989, pp. 176-177), containing a microwave generator, connected via an excitation coupling element with an open measuring waveguide, an oscillation pickup element connected through a detector to an indicator. In this device, when a controlled substance passes through a hollow channel formed by a measuring open waveguide and located at its ends mutually perpendicular to two other open waveguides, information on the controlled physical parameter is obtained by changing the frequency excited in the measuring open waveguide.

 The disadvantage of this device is the error due to the complexity of the procedure for obtaining different polarization of waves in open waveguides.

 The problem solved by the claimed technical solution is to increase the accuracy of measurement.

 This object is achieved in that in the device for determining the density of non-polar substances in the dielectric conduit, containing a microwave generator, first and second communication elements, a microwave detector and an indicator, the output of which is the output of the device, a ring resonator is introduced, made in the form of a convoluted rectangular waveguide, fixed open ends diametrically on the outer surface of the dielectric pipeline, and the output of the microwave generator through the first communication element is connected nen to the input of the ring resonator, the ring resonator output through the second connection element connected to the input of the microwave detector, whose output is connected to the input of the indicator.

 An essential distinguishing feature in the above combination is the presence of a measuring ring resonator.

 In the claimed technical solution due to the properties of the totality of the listed features, measuring the intrinsic resonant frequency of the ring resonator allows us to solve the problem: to provide higher measurement accuracy.

 The drawing shows a functional diagram of the inventive device.

 The device comprises a microwave generator 1, a first coupling element 2, connected to the input of a ring resonator 3, mounted on the surface of the dielectric conduit 4, through which the measured substance flows, a second coupling element 5, connected through a microwave detector 6 to the input of the indicator 7.

 The device operates as follows. The electromagnetic signal from the output of the microwave generator 1 enters the first communication element 2. The output signal of the latter excite electromagnetic oscillations in the ring resonator 3.

где с - скорость распространения электромагнитных волн в свободном пространстве, L_сред - средняя длина кольца, h = 1,2,3,... .In the absence of substance in the pipeline 4, the natural resonant frequency of the ring resonator can be expressed as

where c is the propagation velocity of electromagnetic waves in free space, L _media is the average ring length, h = 1,2,3, ....

где ε- диэлектрическая проницаемость вещества.In the case under consideration, since the ring resonator is fixed diametrically (at the same level against each other) with the open ends on the outer surface of the dielectric conduit, when waves propagating (rotating) through the ring resonator pass through the substance flowing through the conduit, a change (shift) of the intrinsic resonant frequency f _p . Therefore, in the presence of a substance in the pipeline, the formula (1) will take the following form:

where ε is the dielectric constant of the substance.

From formula (2) it can be seen that by the magnitude of the frequency f _p we can judge the dielectric constant of the measured substance.

где

(μ- молекулярный вес вещества, β- поляризуемость вещества, N - число Авогодро), можно получить уравнение, связывающее частоту f_p с плотностью ρ.
Совместное решение выражений (2) и (3) позволяет записать

Отсюда для ρ имеем

Полученное выражение показывает, что путем измерения резонансной частоты кольцевого резонатора можно определить плотность вещества, протекающего по трубопроводу.Based on the use of the Clausius-Mosotti formula (see G. Skanavi, “Physics of Dielectrics”, Gostekhizdat, 1949) expressing the dependence of the dielectric constant ε on the density ρ of non-polar substances

Where

(μ is the molecular weight of the substance, β is the polarizability of the substance, N is the Avogodro number), we can obtain an equation relating the frequency f _p to the density ρ.
The joint solution of expressions (2) and (3) allows us to write

Hence for ρ we have

The resulting expression shows that by measuring the resonant frequency of the ring resonator, it is possible to determine the density of the substance flowing through the pipeline.

In the proposed device for measuring the frequency f _{p, the} signal from the output of the ring resonator with the help of series-connected second communication element 5 and the microwave detector 6 is transferred to the indicator 7. Here, according to the peak of the resonance curve, observed, for example, on the screen of the device for studying the amplitude-frequency characteristics (AFC), it is possible to estimate the magnitude of the frequency associated with the density of a non-polar substance in a dielectric conduit.

 Thus, in the proposed device due to the simple procedure of forming the measuring region at the junction of the ring resonator and the dielectric pipeline, it is possible to determine the density of non-polar substances with higher measurement accuracy.

Claims (1)

 A device for determining the density of non-polar substances in a dielectric conduit, containing a microwave generator, first and second communication elements, a microwave detector and an indicator, the output of which is the output of the device, characterized in that a ring resonator is introduced into it, made in the form of a folded rectangular waveguide fixed open the ends diametrically on the outer surface of the dielectric pipeline, and the output of the microwave generator through the first communication element is connected to the input rotating arm resonator, the output of the ring resonator via a second connection element connected to the input of the microwave detector, whose output is connected to the input of the indicator.