SU1244579A1 - Method of determining concentration of suspended particles in suspensions - Google Patents

Abstract

The invention relates to the field of studying the physicochemical properties of a liquid medium, in particular, to methods for measuring the concentration of particles of a substance suspended in a liquid. The aim of the invention is to increase the sensitivity and accuracy of measurement. According to the invention, the test medium (suspension) is preliminarily pumped with air bubbles until saturation, then an ultrasonic signal is passed through the medium, its output is recorded, in particular, the absorption coefficient of the acoustic signal by the medium is determined and judged by the value of the controlled parameter. 2 Il. with 1C f | JV "ce

Description

The invention relates more to studies of the physicochemical properties of a liquid medium, in particular, to methods for measuring the concentration of particles of a fake suspended in a liquid, and can be used in chemical and paper industry for analyzing the properties of a binary suspension medium by its acoustic parameters. also, for continuous recording of these parameters in the process, i

The purpose of the inventions is to increase the sensitivity and accuracy of measurement of the structure.

FIG. 1 shows a diagram of the device that implements the proposed method; in fig. 2 - graphs of the dependence of the absorption coefficient of ultrasonic oscillations on the concentration of suspended particles in a suspension saturated with air bubbles (curve I) and in a suspension unsaturated with air bubbles (curve II), with a frequency f of ultrasonic vibrations equal to 1.25 MHz.

A device that implements a method for determining the concentration of suspended particles in suspensions contains a generator of radio frequency excitation pulses 1 connected to a radiating piezo transducer 2, a receiving piezo transducer 3 connected through an amplifier 4 to a recorder 5 .. Piezo transducers 2 and 3 are placed in a vessel 6 with the test suspension at a fixed distance from each other. Dp all; liquid (test medium) air bubbles device equipped with a mixer 7.

The way osu1cest is evil is as follows.

Ultrasonic vibrations are passed through the suspension under test, ultrasonic vibrations that have passed through the suspension are taken, and the absorption coefficient of these vibrations is measured. In this case, the test fluid is preliminarily pumped with air bubbles until it is full.

Air bubbles adhere to particles of a substance suspended in a liquid, significantly changing the acoustic parameters of the transmitted ultrasonic wave. The higher the concentration of a substance in a liquid, the greater the number of air bubbles

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lives on the particles of a substance and the greater the contribution of the air particle to the change in the acoustic parameters.

The method is implemented as follows.

Piezo transducer 2, excited by generator 1, emits into the test suspension, saturated with a mixer 7 air bubbles, acoustic waves, which, after receiving and converting the signal to an electrically signal, converter 3 are amplified by amplifier 4 and 5 are fed to the recorder 5. As the medium under study was paper pulp is selected. The concentration of paper pulp was measured by the definition of the absorption coefficient of acoustic waves in the frequency range 1.25–5.25 MHz and varied in the range 0.15–2.0 mg / l.

The results of measurements of the dependence of the absorption coefficient on the degree of pumping of the medium by air revealed the following pattern. As the investigated medium 5 is pumped and thus as the air bubbles adhering to the substance particles increase, the absorption coefficient (ti.) Of the ultrasonic vibrations increases at the beginning and then when the medium becomes saturated with air. From this point onwards, concentration measurements were taken. The measurements were carried out at a signal frequency of 1.25 MHz. The frequency of the signal as the most optimal was selected on the basis of experimental data.

For direct measurement of the concentration, the scale of the recorder 5 was graduated in units of concentration (mg / l). To translate the readings of the recorder 5 into units of concentration, the calibration curve I could also be used (Fig. 2). Dp calibration was used a dry residue method, which consists in filtering a two-component system followed by 1M drying and weighing the dry residue.

A comparison of the results of measuring the concentration of particles of a substance by the proposed method and the usual acoustic 5 IMM method (without using air pumping) is shown in FIG. 2, where curve I corresponds to the case of pumping pulp with air bubbles.

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and curve II - without pumping the pulp. It can be seen from the graph that the slope of direct I is many times greater than the slope of direct II and, therefore, the measurement accuracy in the first case is many times higher than in the second, since the measurement accuracy increases in proportion to the ratio of the tangents of the angles of T and II.

Claims (1)

Invention Formula The method of determining the concentration of suspended particles in suspensions. tgctfc / -) Compiled by S. Volkov Editor A. Dolinich Tehred M. Khodanich Proofreader M. Sharoshi Order 3909/47 Edition 778 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 CEE production and printing company, Uzhgorod, st. Proektna, 4 445794 that is, ultrasonic vibrations are emitted into the suspension under study, ultrasonic vibrations that have passed the suspension are received, 5 and the absorption coefficient of these oscillations is measured, the magnitude of which determines the concentration of suspended particles, which is different in order to increase 10 sensitivity and accuracy measurement, the test suspension is preliminarily but pumped by air bubbles until saturated 1.0 fufg