SU1485066A1 - Photoelectric device for determining dimensions and countable concentrations of particles in fluid flow - Google Patents

Description

The invention relates to the field of instrumentation, in particular to optical devices for monitoring parameters of dispersed media. purpose

is to increase accuracy

inventions

definitions

particle size by eliminating the error caused by the instability of the velocity of particles in the measuring channel. The sensing element 1, through the measuring channel 12 of which the test fluid flows, is mounted in the pipeline 2 on the bearings 3 movably. The rotation of the sensing element 1 by means of an electric drive 4 allows you to adjust the speed of the fluid with particles in the measuring channel 12. The system of tracking the speed of the liquid in the measuring channel 12, made using the differentiator 5, the linear detector 6, the first 7 and second 8 low-pass filters, the divider 9 voltage, unit 10 comparison and the source 11 of the reference voltage allows you to stabilize the velocity of the particles. Due to this, the effect of the instability of the velocity of the particles on the measurement of the duration of the pulses is eliminated, and thereby the accuracy of determining the particle size is increased. .2 il.

£

1485066

The invention relates to instrumentation technology, in particular to optical devices for monitoring parameters of dispersed media, and can be used to determine the size and concentration of particles in fluid flows.

The purpose of the invention is to improve the accuracy of determining the size of particles by eliminating errors caused by the instability of the velocity of particles in the measuring channel.

FIG. 1 shows a block diagram of a device for determining the size and number concentration of particles in a fluid flow; in fig. 2 shows section A-A in FIG. one.

The device contains a sensitive element 1, pipeline 2, bearings 3, electric drive 4, differentiator 5, linear detector 6, first 7 and second 8 low-pass filters, voltage divider 9, comparison unit 10, reference voltage source 11, measuring channel 12, radiator 13 , the photodetector 14, the fairing 15, the aperture 16. FIG. 1 also shows a sampling tube 17.

The device works as follows.

In the pipe 2 through the sensitive element 1 passes a liquid containing suspended particles. With the passage of particles through the measuring channel 12 at the output of the photodetector 14, a signal appears

5 (a, 1) = A (a) - 1 (1), where A (a) is the amplitude of the pulses;

a is the particle size;

1 (1) is the normalized function describing the pulse shape.

The pulse duration τ is determined by the width of the light beam K and the flow rate of the fluid V through the measuring channel:

τ = Η / ν.

The signal 5 (a, b) is fed to the second low-pass filter 8 and to the differentiator 5. At the output of the differentiator 5, the electrical signal has the following form:

- = A (a) · G (1),

where Γ ^x (4) is the time derivative of the normalized function describing the pulse shape.

This signal is fed to the input of the linear detector 6, the output of which

1C ^! = A (a). | 1 '(1) | .

thirty

35

40

45

50

Next, the signal enters the first low-pass filter 7, is averaged and at its output takes the form

1 5 ^g , s15 (a, C

T.4 ’01

_? A (a) 'T

81 = 2 $ 1 '(1) 81 = ¹ ~ Chg.

55

2A (a) T

(one)

where T is the time constant of the lowpass filter 7.

At the same time, the signal 5 (a, 1) goes to the second low-pass filter 8, where it is averaged and takes the form

ten

± G 5 (1) 81 = / ^ .— 5, ¹

(1) 81 =

^) / (1 (1) 81 = ^ =

^eleven

_K _L A (a) t V '

(2)

1 / g.

15

20

where K / = (t ({) b! is the area under the function ί (I), which is a constant parameter for this sensor.

The voltage divider 9 divides the voltage from the first 7 and second 8 low-pass filters defined by expressions (I) and (2), respectively. As a result, at the output of the divider 9 voltages, the signal is described by the expression

25

Where

2A (a). _g KM (a) _ 2U „ _ν t · ί T 'ν' K / b ^γ

2 - constant for this sensor coefficient.

Thus, the voltage at the output of the voltage divider 9 is proportional to the flow rate of the fluid in the measuring channel 12. This voltage is applied to the input of the comparator unit Yu, the second input of which from the reference voltage source 11 receives the reference voltage corresponding to the nominal flow rate of the liquid through the measuring channel 12. The error signal at the output of the unit Yu comparison controls the actuator 4, which rotates the node of the sensing element I at an angle such that the flow rate of the fluid in the measuring Channel 12 remains unchanged and is equal to nominal.

Thus, the device reduces the measurement error of particle size associated with changes in the flow rate of fluid in the pipeline.

Claims (1)

Claim A photoelectric device for determining the size and counting concentration of particles in a fluid flow, containing a pipe with a diaphragm- inside which a sensing element provided with a fairing is placed perpendicular to the axis of the pipeline, made in the form of an emitter, the optical measuring channel oriented perpendicular to the optical axis of the radiator , and photo1485066 receiver, characterized in that, in order to improve the accuracy of determining particle sizes by eliminating the error caused by the instability of particle velocity in the measuring channel, a differentiator, a linear detector, the first and second low-pass filters, a voltage divider, a comparator, a reference source are entered into the device voltage, the electric drive, while the sensitive element is mechanically connected to the electric drive and installed in the pipeline with the help of bearings that can be rotated around axis coinciding with the optical axis of the emitter, at an angle of up to 90 ° relative to the axis of the pipeline, and the photoreceiver output is connected via a serially connected differentiator, linear detector and the first low pass filter to the first input of a voltage divider, the second input of which is through the second low pass filter with the output of the photodetector, and the output - with the first input of the comparator, the second input of which is connected to the output of the reference voltage source, and the output - to the terminals of the electric drive. A-l (ΰυζ.ζ