RU2356028C1 - Device for proximate analysis of fluid industrial-class purity - Google Patents

Abstract

FIELD: physics, measurements.

SUBSTANCE: invention relates to instrument making, in particular, to devices designed to measure the amount of mechanical impurities in industrial fluids, e.g. water, liquid fluids, oils, coolants etc., and to measure their particle sizes. The proposed device comprises radiation source, fluid flow passage chamber, photo receiver made up of a photo diode, microcontroller and display. Aforesaid photo diode registers the magnitude of signal dissipated from radiation particles in finite range of angles of 0.12 to 0.58 rad selected empirically so that the magnitude of dissipated radiation signal from the photo diode output depends linearly from the impurity grain size.

EFFECT: expanded range of measured grain sizes, reduced errors of measurements.

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Description

The technical field to which the invention relates.

The invention relates to the field of instrumentation, and more particularly to devices for determining the amount of solids in industrial liquids - water, liquid fuels, oils, coolants, etc.

State of the art

A known device for measuring mechanical impurities in oil products [Bikhmukhametov K.A., Selyatitsky V.G. "A device for measuring mechanical impurities in petroleum products." http // www.gsm.kip-radio.ru], containing an optical sensor, including a measuring cell, optical lenses, a light emitting diode, and two photodetectors - scattered and transmitted radiation, and the scattered radiation receiver is approximately 90 ° to the probing radiation. Photodetectors measure the scattered and passing through the measuring cell filled with liquid, the radiation of the LED. It is assumed that the intensities of the scattered and transmitted radiation are proportional to K and 1-K, respectively (K is the coefficient of radiation scattering by mechanical impurities). The electronic part of the device calculates the coefficient of radiation scattering by mechanical impurities K. The disadvantages of the device are:

- measurement of only the integral characteristics of the parameters of mechanical impurities (volumetric concentration of impurities);

- the impossibility of determining the coefficient of scattering of radiation on mechanical impurities with different particle size distribution;

- the dependence of the readings on the particle size distribution of impurities.

The device GRAN-152 [TEKHNOPRIBOR. Chemical control devices. Catalog 2002, Moscow, p.22]. The device consists of a radiation source, a measuring cell, an optical system and a photodetector. The principle of operation of this device is based on measuring the signal from the output of the photodetector that occurs when particles cross the probe radiation, which is briefly shielded. In this case, pulses are generated at the output of the photodetector in an amount equal to the number of particles, and the amplitudes are proportional to their size. The disadvantage of this device is the quadratic dependence of the pulse amplitude on the particle diameter, because in this case, the particle extinction cross section is measured proportional to d ² (d is the projection diameter of the particle). This circumstance limits the dynamic range of particle size measurement due to saturation of the signal of the photodetector when measuring large particles.

The closest of the technical solutions is the liquid cleanliness control device PKZH - 904A [http / www.tesar-centr.ru]. The device has a chamber with a vertical liquid channel, perpendicular to which a illuminator and a photodetector are located on one optical axis. The camera on both sides is limited by transparent glasses. A diaphragm is located between the illuminator and one of the glasses, restricting the luminous flux from the light source.

The operation of the device is based on the registration by the photosensitive element (photodiode) of the change in the light flux from the light source (LED) during the overlapping of the part of the light flux with a separate particle moving with the flow of the controlled fluid. The luminous flux from the light source is directed perpendicular to the fluid flow and completely covers it (along the cross-section of the fluid flow), which allows you to control the fluid passing through the sensor of the device. Changes in the electrical signal (current) of the photodiode caused by particles of contaminants in the liquid are proportional to the size of the particles, and the duration of these changes is equal to the time the particle travels through the sensitive volume of the sensor. The electrical signals of the photodiode are amplified, analyzed by amplitude and distributed according to the corresponding size ranges indicated on the instrument panel [http / www.dvgups.ru]. The disadvantage of this device is also the quadratic dependence of the pulse amplitude on the particle diameter caused by the measurement of the extinction cross section and the low measurement accuracy due to this nonlinear dependence.

A device for express analysis of industrial purity of liquids consists of two functional parts: an optical system and a device for converting an electrical signal into a digital code with indication of measurement results on a graphic liquid crystal display (LCD). The invented device extends the range of sizes of the measured particles and reduces the error of their measurement.

The optical system of the device for express analysis of industrial purity of liquids (figure 1) consists of a probe radiation source (laser) 1, a collimator 2, a beam splitter plate 3, a reference photodiode 4, two lenses 6 and 7, and a photodiode 8. A liquid stream directed perpendicular to the probing radiation, forms at the point of intersection with it the working volume of the jet 5. The scattered radiation is collected by lenses 6 and 7 and is focused on the photodiode 8, recording the magnitude of the signal and the intensity of the scattered radiation.

It is known that the amplitudes of signals of scattered radiation S (P) depend on the range of scattering angles (β ₁ ... β ₂ ) [K. Boren, D. Hafmen. Absorption and scattering of light by small particles. Moscow: Mir, 1986, p.141].

It is also known that the magnitude of the scattered radiation signal I (d) is proportional to S ² (β) [G. van de Hulst. Light scattering by small particles. Publisher of foreign literature. M., 1961, p. 42].

The device measures the scattered radiation signals I (d) in a finite range of angles, which is empirically selected in such a way (from β ₁ = 0.12 to β ₂ = 0.58 radians) that the magnitude of the electrical signal from the photodiode linearly depends on the particle size of the pollutant d.

Electrical signals from photodiodes 4 and 8 are fed to a device for converting an electrical signal into a digital code (figure 2).

The device for converting an electrical signal into a digital code includes:

- converters of photocurrent to voltage - 9 and 10;

- an adjustable voltage amplifier - 11;

- control device - 12;

- microcontroller - 13;

- liquid crystal display (LCD) - 14;

- power supply (adapter or battery) - 15.

The electrical signal from photodiode 8 (figure 1) in the form of a photocurrent pulse is converted by the photocurrent converter to voltage 9 (figure 2) into a pulse voltage, the amplitude of which is directly proportional to the particle size d, and their number is proportional to the particle concentration. Next, the pulse signal is supplied to an adjustable voltage amplifier 11, which is made with a variable gain. The gain is switched automatically depending on the amplitude of the signal using the control device 12. These pulses are fed to an analog-to-digital converter (ADC), which is part of the microcontroller 13, where their amplitudes are converted into a digital code. At another ADC included in the microcontroller, a signal is received in the form of a slowly changing voltage from the output of the photocurrent converter to voltage 10 of photodiode 4 (Figure 1), which registers the signal value of the probe radiation source. Regarding this signal, the information displayed on the LCD is normalized 14. The microcontroller 13 provides control over the operation of the emitter; synchronization of the operation of the control device 12; mathematical processing of signals and output of the results of their processing on the LCD.

Claims (1)

A device for express analysis of industrial purity of liquids, consisting of a radiation source, a working volume of a liquid jet, a photodetector including a photodiode that records the magnitude of the scattered radiation signal, a microcontroller and a scoreboard, characterized in that the photodiode registers the magnitude of the scattered radiation signal in the final the range of angles (0.12 ... 0.58 rad), which is chosen empirically so that the magnitude of the signal from the output of the photodiode linearly depends on the particle size of the pollutant.

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