RU4168U1 - VLOGOMETRIC SENSOR FOR LIQUIDS - Google Patents

Abstract

A moisture-measuring sensor for liquids, consisting of two cylindrical electrodes located coaxially in one another and connected by dielectric holders, characterized in that an emitter and an ultrasound receiver (US), an amplifier, a detector, a start cascade, a high-frequency (HF) generator are additionally introduced into it, a temperature-frequency sensor, a shaper, a capacitance-frequency converter and a digital computing device (CVC), wherein the ultrasonic emitter is included in the positive feedback circuit of the RF generator, the ultrasonic receiver with is single with the input of the amplifier, the output of which is connected to the inputs of the detector and the driver, the output of the driver is connected to the first input of the CVC, the output of the detector is connected to the input of the start-up cascade, the output of which is connected to the control input of the RF generator, the temperature-frequency sensor is connected to the second input TsVU, cylindrical electrodes are connected at the ends by dielectric holders made in the form of soundproof bushings, each of the cylindrical electrodes is electrically connected to the input terminals of the capacitance-frequency converter , the output of which is connected to the third input of the CVC, the ultrasonic emitter and receiver are made in the form of piezoceramic rings with metallization on cylindrical surfaces, rigidly fixed to the external cylindrical electrode in places that do not coincide with the installation locations of the dielectric holders, and spaced apart from each other by a considerable distance exceeding the width of the piezoceramic rings.

Description

VAGOGETRIC SENSOR W 1 YDKOST

The utility model is the subject of measurement technology and can be used in technological control systems for moisture of various multicomponent liquids (MCM), for example, oil at oil production facilities or milk in the food industry.

The diesel-sensing sensors for determining the moisture content of MKM are widely known, the principle of operation of which is based on measuring the dielectric constant of the capacitance) MK1, placed between the plates of the measuring capacitor P. But the capacitance, in addition to the moisture content W, also depends on a number of parameters that must be taken into account. Such interfering parameters are, first of all, density P, free gas content h, temperature t. By measuring these parameters, appropriate corrective actions can be entered into the moisture content measurement result. Usually this is realized using a combination of separate sensors measuring, and, t; the moisture content of V is then determined by substituting the obtained values in empirical formulas 2.

For the implementation of in-line dielcometric sensors, the plates of the measuring capacitor are usually made in the form of coaxial cylinders. Such a sensor may be a section of the pipeline.

Closest to the proposed is a sensor for measuring humidity 31, consisting of two cylindrical electrodes located coaxially in one another, and connected by dielectric holders. tsf, which are not taken into account in the framework of this design.

The problem solved by the claimed utility model is to increase the accuracy of measuring moisture content of MKi by a diesel sensor by taking into account the influence on the measurement result of the density, gas content and temperature of MKI.

The problem is solved in that in a known moisture meter, consisting of two cylindrical electrodes located coaxially in one another, and connected by dielectric holders, an ultrasound transducer and an ultrasound receiver (US), an amplifier, a detector, a start cascade, a high-frequency (HF) generator are additionally introduced, temperature-frequency sensor, driver, capacitance-frequency converter and digital computing device (CBU), wherein the ultrasonic emitter is included in the positive feedback circuit of the RF generator, the ultrasonic receiver is connected with the input of the amplifier, the output of which is connected to the inputs of the detector and the driver, the output of the driver is connected to the first input of the CVU, the output of the detector is connected to the input of the start-up cascade, the output of which is connected to the control input

An RF generator, a temperature-frequency sensor connected to the second input of the CVC, cylindrical electrodes connected at the ends by dielectric holders made in the form of soundproof bushings, each of the cylindrical electrodes is electrically connected to the input terminals of the capacitance-frequency converter, the output of which is connected to the third input of the CVU, the ultrasonic emitter and receiver are made in the form of piezoceramic rings with metallization on cylindrical surfaces that are rigidly fixed on the external cylindrical electrode in places that do not coincide giving dielectric holders with mounting locations, and spaced from each other by a distance significantly exceeding the width of the piezoceramic rings.

- 2 lyre bushings 3 (the number of bushings is negligible); the space between the electrodes is filled with the test fluid. On the outer side of the external electrode i in places that do not coincide with the installation locations of the bushings 3, the ultrasonic emitter 4 and the ultrasonic receiver 5 are rigidly fixed, which are piezoceramic rings with metallization on cylindrical surfaces; the rings are spaced from each other by a distance significantly exceeding the width of the rings. The ultrasonic emitter 4 is included in the positive feedback circuit of the RF generator b and is its frequency-setting element. The UZ 5 receiver is connected to the input of the amplifier 7. The output of which is connected to the detector 8 connected in series and to the start cascade 9. As well as to the input of the driver 10; the output of the start-up cascade 9 is connected to the control input of the RF generator b, and the output of the driver 10 is connected to the first input of the CVU 13. The cylindrical electrodes 1 and 2 are connected to the input of the frequency capacitance converter I. The temperature-frequency sensor 12 is connected to the second input of the CVU 13, and the third the input of the CVU 13 is connected to the output of the Converter 11.

The main idea of this utility model is to combine, within the framework of a single design, various elements with which the following measurements are taken together;

 - dielectric constant

CQ - ultrasound velocity in the fluid volume,

from. - ultrasound speeds in the waveguide wall,

t - temperature

The sensor operates as follows.

At the initial moment of time, when the power is turned on, the start-up cascade 9 generates a single normalized pulse of 2 G duration, gate the RF generator 6. The frequency-determining element included in the positive feedback circuit of the RF generator 6 is an ultrasonic emitter 4 together with an MKI volume between

- 3 by the tubular electrodes 1 and 2. The resonant mode in the RF generator 6 occurs when a standing 93 wave is established between the electrodes i and 2 (i.e., when an integer number of half-wavelengths is stacked in the gap), And since the wavelength (or Since the propagation velocity of the ultrasonic wave in the MKM volume) depends on the properties of MK1 (gas content, dispersion, etc.), the generation frequency is also a function of these properties. The resonant device described in 4, p.2251 works in a similar way.

The excited pulse of ultrasound propagates not only in the gap between the electrodes 1 and 2, but also along the thin wall of the waveguide - electrode 1 at a speed of s., Reaching in time T

receiver 5. Speed c. , and hence the time T, depend on the properties

1 in contact with the waveguide 4, p.2261. The signal from the receiver 5 is amplified by the amplifier 7 and fed to the former 10, from where a packet of normalized rectangular pulses with a repetition rate f is supplied for further processing to the CVU 13. From the output of the amplifier 7, the RF pulse is also transmitted to the detector 8, where it is converted into a video pulse, which, passing through the start cascade 9, it is normalized by amplitude and duration (t) and starts the RF generator 6. again. The cycle repeats. The frequency of autocirculation of bursts of pulses F - 1 / T

With. This frequency is also measured in the DAC 13. In the algorithm of the DAC

13 also (except for determining and) measures the repetition rate of pulses generated by the capacitance-frequency converter, which is a self-generating circuit with a frequency-determining element - a capacitor, the plates of which are formed by electrodes 1 and 2. The capacitance of this capacitor depends on the dielectric constant of the MCM, therefore, from the converter And on the second input of the TsVU 13 will receive pulses with a repetition period. The output signal of the temperature-frequency sensor 12, which is a rectangular pulse with a repetition rate F., is also fed to the CVU (to the second input). Thus,

- 4 the Central Bank 13 receives all the necessary set of parameters expressing c, Cg, € and t, according to which the moisture content of W is calculated by the formula: W kg + + + kjC + t CD - where kg ... k are constant coefficients determined by calibration , is the measured value of the dielectric constant MKS, Co and c are the measured values of the ultrasonic velocity in the volume of the liquid and along the waveguide wall, respectively, t is the measured value of the temperature MKS. The coefficients kQ ... k are determined during the initial calibration of the device based on experimental data as follows. A series of measurements (16 measurements in total) is made according to the planning matrix of the full factorial experiment 2 5, p. 801, in which each of the controlled factors (W - moisture content, n - gas content, p - density, t - temperature) is varied at r two levels . By processing the experimental data (for example, the Yates method 5, pp. 87-881), we find the coefficients flfc - 4 polynomials of the first degree:, / 2) S- о („o (if - - й4 G.) 2 more similar equations are constructed similarly for c and - / o- / iW.-t, 3) - (- (- 5 (temperature t can be considered a known quantity), we obtain equation (1), in which the coefficients k- are expressed in terms of (U. / g, Y -V The measurable quantities c and c, formally described by the empirical equations (2), (3), (4), are integral estimates of many properties of MKI, depending on the chemical and particle size distribution of the mixture and affecting 6 mixture. One of these quantities (CQ) to a greater degree depends on gas content item, the other (s)

- FROM density p. Therefore, it is legitimate to use them as corrective signals when measuring moisture content with capacitive moisture meters.

When implementing the sensor, the following additional conditions and recommendations must be observed:

- the wall thickness of the outer electrode 1 should be significantly less than the length of the excited ultrasonic wave;

- the entire electronic circuit, which includes nodes 6-11LZ,

should be located in close proximity to the receiver 5 and the emitter 4;

-the duration of the pulse T. formed by the start cascade should be several times shorter than the time necessary for the pulse to propagate along the wall of the electrode 1 from the emitter 4 to the receiver 5, but at the same time, at least 10-20 oscillations should fit into the 2G time interval frequency f. determined by the occurrence of a standing wave in the space between the electrodes 1 and 2;

-the frequency setting f can be controlled by tuning the RF generator 6. which is an electronic self-excited amplifier with a piezo emitter 4 included in the positive feedback circuit; tuning is reduced to changing the bandwidth or gain of this amplifier;

- 6 for reasons of ensuring sufficient electrical capacitance of the sensor;

- to avoid contamination and deposits, the electrodes 1 and 2 are made of corrosion-resistant metal, and their working surfaces in contact with the MCM are polished;

-CVU is performed on the basis of a single-chip microZVM chip,

A specific example of a sensor implementation;

When the outer diameter of the outer electrode is 30 mm and the wall thickness of 0.5 mm, the outer diameter of the inner electrode is 24 mm, the gap between the electrodes is 2 mm, the length of the electrodes is 120 mm, the distance between the piezoceramic rings is 100 mm, and the ring width is 8 mm, the following signal parameters can be obtained ;

- excitation frequency of the RF generator, 5 MHz;

- duration of ultrasonic pulse 20 μs;

-period of autocirculation of pulses T 70 µs;

sensor capacity at W-0 pF.

The inventive sensor has the following advantages compared to analogues;

1) The sensor automatically records factors affecting the result of measuring moisture content, thanks to the combined measurements of several different MKS parameters.

2) The sensor has a compact design, which is obtained due to the constructive and functional combination of elements of acoustic and capacitive measuring transducers;

as a result, there is no need to place and maintain several separate sensors.

- 8 4) The inventive sensor differs from its analogues in a greater noise immunity of the measurements, because All participation in humidity calculations is expressed by means of frequency or time parameters, which are little affected by interference.

The sensor of the device can be used both as a poured element for individual samples of liquids, and as a section of a pipeline with continuously transported liquid.

Sources of information:

1.Zaitsev L.A., Panarin V.V. Information collection and processing systems for tank farms. - M .: Nedra, 1984, pp. 103-105.

2.Belyakov V.L. Automatic control of oil emulsion parameters. - M .: Nedra, 1992, p. 78.

3. Theory and practice of rapid control of humidity of solid and liquid materials / E.S. Krichevsky, V.K. Benzar. M.V. Benediktov et al. - I .: Energy, 1980, p. 9 (prototype).

4.Kivilis S.S. Density meters. - M .: Energy, 1980.

5.Adler Yu.P., Markova E.V., Granovsky Yu.V. Planning when searching for optimal conditions. - M.: Science, 1976.

V.S. Mernakov

Claims (1)

A moisture-measuring sensor for liquids, consisting of two cylindrical electrodes located coaxially in one another and connected by dielectric holders, characterized in that an emitter and an ultrasound receiver (US), an amplifier, a detector, a start cascade, a high-frequency (HF) generator are additionally introduced into it, a temperature-frequency sensor, a shaper, a capacitance-frequency converter and a digital computing device (CVC), wherein the ultrasonic emitter is included in the positive feedback circuit of the RF generator, the ultrasonic receiver with is single with the input of the amplifier, the output of which is connected to the inputs of the detector and the driver, the output of the driver is connected to the first input of the CVC, the output of the detector is connected to the input of the start-up cascade, the output of which is connected to the control input of the RF generator, the temperature-frequency sensor is connected to the second input TsVU, cylindrical electrodes are connected at the ends by dielectric holders made in the form of soundproof bushings, each of the cylindrical electrodes is electrically connected to the input terminals of the capacitance-frequency converter , the output of which is connected to the third input of the CVC, the ultrasonic emitter and receiver are made in the form of piezoceramic rings with metallization on cylindrical surfaces, rigidly fixed to the external cylindrical electrode in places that do not coincide with the installation locations of the dielectric holders, and spaced apart from each other by a considerable distance exceeding the width of the piezoceramic rings.