SU1469399A1 - Method and apparatus for measuring humidity of loose matter in a stream - Google Patents

Abstract

This invention relates to a moisture metering technique on a microwave. The purpose of the invention is to enable the measurement of humidity in a continuous mode. The device that implements this method of measuring humidity contains gr.r. 1. UHF, decoupling unit 2, ctr {rkul - torus 3, resonator 4 with elec- ture contact 5, detector 6, phase system of automatic frequency tuning, consisting of a directional coupler 7, valves 8 and 9, a mixer 10 and an amplifier 11, as well as a recording system consisting of a differential 12, a digital frequency meter 13 of the counter 14, a decoder 15 and the arithmetic logic unit 16. The essence of this measurement method is that the pre-calibrated resonator 4 is placed in flow of the bulk solids under study. Then, the resonant frequency of the resonator 4 is found and, changing the value of the coefficient. connection, achieve equal zero at the output of the resonator 4 at the signal frequency. Next, fix the resulting value of the coefficient. connections and by f-le determine the humidity. 2 sec. f-ly, 1 zp f-ly, 3 il .. Od CO On will perform. Htxahuift

Description

:)

The jubilee relates to a technique of moisture metering at ultra-high frequencies and, in particular, can be used to measure the moisture content of powdered milk in tower sizing plants of continuous operation.

The purpose of the invention is to make it possible to measure moisture in a continuous stream while eliminating the influence of the density of a substance.

Fig. 1 shows a diagram of a device for measuring the humidity of solids, substances in a stream; FIG. 2 shows the resonator design; figure 3 is a view of And figure 2,

The device for measuring the moisture content of solids contains a microwave generator 1, a decoupling unit 2, a circulator 3, a resistor 4 with a communication element 5, a detector 6, a phase control system consisting of a directional coupler - 7, the first and second valves 8 and 9, the mixer 10, the amplifier 11, and the registration system, consisting of a differentiator 12, 1 and a front frequency meter

13, counter 14, decoder 15, arithmetic logic unit 1b.

The resonator 4 consists of a cylindrical circular tube 17 with a communication element formed by openings 18 in which nI -In diodes are installed. The resonator 4 is excited by two equal lengths of a rectangular waveguide 19 and 20 rolled up around the resonator wall and short-circuited metal plugs 21. The rectangular waveguides 19 and 20 t are connected by circular flange 22 and adapter to circular 3. 01 spans. 18 are located one from the other on. a distance equal to the wavelength in rectangular waveguides 19 and 20 at the places where the magnetic component of the field is located. On the side of the resonator, 4 holes 18 are closed with fluoroplastic plugs. The waveguides 19 and 20 facing the resonator 4 narrow wall. As a result, only a type-E transverse magnetic wave is excited in the resonator 4 (, (,. |;....

The principle of the method for measuring the moisture content of a granular substance is determined that the signal at the output of the detector 6 at the time of resonance is defined as -. by the ratio

, YU

15

20 25

 (,.,. Sh..P ,, e.

  T7-7ShShSh

(one)

where QO / QCB is the coupling factor, the Q of the empty resonator 4 and the Q of the coupling, respectively J

f, f is the natural frequency of the empty resonator 4 and the resonator 4 containing the substance under study} f, is valid and imaginary part of the dielectric constant of the substance,

. From (1) it follows that there is such a connection (critical), in which .. The value of this relationship is determined by the relation

, „. , (2)

thirty

35 40 45 JQ Thus, to determine the value of / (-1), it is necessary to measure d and Q in advance, and when introducing the test substance into the resonator, measure the frequency and fix the mode, the cause of the critical coupling coefficient (i, which allows determining Hr rank (-1) by the formula f

PIT

and humidity w according to the formula

W

(3)

(four)

where K is the coefficient: € nt- defined by

empirically for each specific type of bulk material and controlled humidity range. A method for measuring the moisture of a CW material stream 1E is carried out as follows.

Place the pre-calibrated (with known values of f and Qg) resonator 4 into the flow of the studied bulk material, find the resonant frequency of the resonator 4 and, changing the value of the coupling coefficient, achieve a zero value at the frequency of the signal at the output of the resonator. The resulting value of the coupling coefficient is fixed and the humidity is determined by the formula

W - K (,) 5 (f ™ ypThe device for measuring the humidity of flowing substances in the stream works

in the following way.

The generator 1 is continuously adjusted to the corresponding frequency of the resonator 4 by means of a phase-controlled AFC system, containing a mixer W and an amplifier 11. The signals to the mixer 10 are received from the generator 1 through the directional coupler 7 and the valve 9 and from the resonator 4 through the communication element 5, the circulator 3 and valve 8, the link coefficient is changed by changing the number of open nipin-iodides installed in the link elements 5. Clock pulses from a single output of a digital frequency meter 13 are fed to the input of a counter 14, which via a decoder 15 controls the connection of nipin diodes. The signal at the output of the detector 6. Monotonously varies. when each nipin diode is connected in series and reaches its extreme (zero) value at the moment when the coupling coefficient takes on a value, this moment differentiator 12 generates a pulse arriving at the arithmetic logic unit 16, to the other inputs of the arithmetic logic unit 16 digital information is received about the frequency of the generator from the second output of the digital frequency meter 13 and about the number of included nip-diodes from the output of the counter 14, This information is processed in the arithmetic-logic unit 16, which controls an additional mechanism regulating the drying of the flow of bulk material.

Claims (3)

1. A method for measuring the moisture content of solids in a stream, consisting in the excitation of a resonator containing the test substance O and ten  . - 15 20 25 I dividing the intrinsic frequency of the resonator by fixing;), (a string signal at the resonator output, characterized in that, in order to enable measurement in a continuous mode, the magnitude of the coupling coefficient with the resonator is changed to obtain a zero value of the extreme signal and The magnitude of this coefficient p of the coupling with the resonator is used to determine the humidity and the formula v (Kp-DjCf IfTq; where K is the calibration coefficient 4 | f, f - empty resonant frequencies and filled resonators; QP - Q of an empty resonator ... 2. A device for measuring the moisture content of solids in a stream, consisting of a series-connected microwave generator and a decoupling unit, a circulator, to the first input of which a resonator is connected via an element of communication, and a detector different from the second one, THAT In order to enable the measurement of humidity in a continuous mode, a system is introduced into it. The 2D automatic frequency control, consisting of a directional coupler connected between the output of the coupling unit and the third inlet of the circulator, is connected to the first and second outlets of the coaxial channel by the first valve, the output of which is connected to the first input of the mixer. which through the amplifier is connected to the control input of the microwave generator, 45 between the detector input and the second input of the mixer, the second vein is turned on. til, the detector output is connected to a series-connected differentiator and arithmetic logic 50 block, to the output of the microwave generator is connected the input of a digital frequency meter, the first output of which is connected to the second input of the arithmetic logic unit, and the second through a counter to 55 by the third input of the arithmetic logic unit, with the depressor connected between the resonator and the output of the counter, and the communication element is adjustable. 3. The device according to claim 2, characterized in that the communication element with the resonator is made in the form holes in which are installed nipin-diodes. 21 sho fi1. Z 17 (. J