SU1681193A1 - Vibration sensor of density - Google Patents

Abstract

The invention relates to a measurement technique, in particular to vibration density sensors, and can be used in the refining industry. The purpose of the invention is to improve the measurement accuracy. The sensor contains a resonator made in the form of two identical parallel tubes rigidly connected to the bases, a system for supplying and discharging a liquid, as well as a system for exciting and receiving oscillations. To eliminate the influence of fluid pressure on the measurement accuracy, two compensating bellows were inserted into the sensor, interconnected by a nozzle and forming a closed internal cavity connected to the fluid supply system. The bottom of each compensating bellows is rigidly connected to the base, and the effective area of the compensating bellows is equal to the cross-sectional area of the resonator tubes. 1 il.

Description

The invention relates to a measurement technique, in particular to devices for measuring the density of a liquid, and can be used in the oil refining industry.

The purpose of the invention is to improve the measurement accuracy.

The drawing shows the proposed sensor, the overall appearance.

The sensor contains a resonator in the form of two identical parallel tubes 1 interconnected by a system of elastic jumpers 2 installed between the central part of the resonator and its rigid bases 3, and two identical compensating bellows 4 located between and parallel to the tubes 1. The bellows 4 with open ends are interconnected by pipe 5, and the closed ends are rigidly attached to rigid bases m 3 by means of stops 6. The pipe 5 in its middle part is fixed in the sensor case by elements 7. The ends of tubes 1 are connected with four equal bellows 8 two distributors 9 and 10 liquids, respectively, for input and output of the test liquid. The internal closed cavity 11 formed by the pipe 5 and the bellows 4. is communicated by means of the flexible pipe 12 with the inlet distributor 9 of the liquid. The resonator excitation system consists of a 13-oscillation receiver, an exciter 14, and an amplifier 15. A frequency meter 16 is designed to record the sensor output signal.

About 00

about

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The sensor works as follows.

The test fluid enters the sensor through the fluid inlet distributor 9 and through the expansion bellows 8 and the fluid outlet distributor 10 leaves the sensor. At the same time, the investigated liquid through the fluid inlet distributor 9 and the flexible pipe 12 enters the closed cavity 11, the excitation system leads to self-oscillations in antiphase of the resonator tube 1. The frequency of self-oscillations is recorded by the frequency meter 16.

The oscillation frequency of the resonator tubes, without taking into account the influence of the velocity of the medium under study and in the presence of some hydrostatic pressure P of the medium, is determined by the expression

A V. „,.,.„ L2PSTP

.

516

side;

A + p - EdV-O where f0 is the oscillation frequency of empty pipes; e is the modulus of elasticity of the tube material;

L-length of the tubes;

n D / d is the relative wall thickness of the tubes;

D, d - outer and inner diameters of the tubes;

A 5 Trpm / 5st is the constant of the resonator;

ZTR is the cross-sectional area of the tubes;

Zet is the cross-sectional area of the tube wall;

RM - the density of the material of the tubes;

p is the density of the test liquid.

The value of f0, in turn, is determined by the expression

0.907 UE (P2 ...-).

In the presence of pressure P of the test fluid in cavity 11 on the side of the compensating bellows 4, the tubes act on

Strength stretch Proust, each of which is determined by the expression

Rrast R5eff,

where Zeff is the effective area of the compensating bellows 4.

In this case, the oscillation frequency of the resonator tubes 1 is determined by the ratio

ten

f

-L

A + p

11-0,

516

-rr

(Srp Zeff))

Obviously, if the BEFF Srp, then the oscillation frequency of the resonator tubes 1 is determined only by the density of the flowing fluid:

-but

20 ° A + p

those. the pressure of the test liquid does not affect the accuracy of the density measurement.

Claims (1)

The Vibration Density Sensor, comprising a resonator made in the form of two identical parallel tubes with a system of elastic jumpers rigidly connected to the bases, two fluid distributors connected to the tubes through four oscillating bellows, an excitation and reception system, characterized in that In order to improve the measurement accuracy, two identical compensating bellows are additionally introduced into it, interconnected by a nozzle and forming a closed internal cavity, connecting One of the liquid distributors, the bottom of each compensating bellows is rigidly connected to the base, and the effective area of the compensating bellows is equal to the cross-sectional area of the resonator tubes. gptt about | 5s ° o |