SU436274A1 - DEVICE FOR MEASURING THE ASHITY OF ANALYSIS - Google Patents

Description

one

The invention can be used as an analyzer for the quality of minerals in the process of their enrichment.

Apparatuses for measuring ash content of coal are known, based on the relationship between the ash content and dielectric properties of a sample at high frequencies, which contain oscillators with sensors included in their circuits. In these devices, as a result of circuit detuning, the grid or anode current of the oscillator changes in proportion to the ash content.

However, these devices do not provide a detuning from the effect on the measurement results of fluctuations in the humidity of the product and therefore are used to analyze individual samples that have been dried to a certain condition.

In addition, the results of ash content measurements by these devices are significantly distorted by active sample losses, which, as a rule, do not remain unchanged over time.

In order to achieve measurement continuity in the conditions of variable material humidity and active losses, the proposed device is equipped with two generators of two fixed frequencies, to which passive RLC, two-pole switches connected in parallel with a probe, are connected through loads

(elements of Rx and C) switches, in which the inductance is connected to one output (LM and ZM are two-terminal respectively), and the other has capacitance (C and C) whose common point is connected to a common point of two-terminal, and the outputs of both two-terminal through detectors and the amplifiers are connected to a comparison device, the output of which is connected to the recording device through an averaging filter.

The drawing schematically shows the proposed device.

To ensure simultaneous analysis

at both frequencies of the same flow section, double capacitive

a sensor (elements Rx, Cx, R, C), the middle electrode of which is connected to a common point of two-terminal networks.

The proposed device is based on research results showing that the difference in the dielectric constant S of a carbon sample, measured at two frequencies, does not depend on the sample moisture, but is proportional to the ash content of the coal.

To measure this difference of dielectric constant values e with the exclusion of the effect of active loss RX oscillations, passive /, C-two-pole properties are used at each frequency, the impedance parameters of which are abruptly changed (modulated) switched alternately by means of an inductance switch and a capacitance with the same reactive modulus resistance. The parameters of both two-terminal networks are chosen so that when the sensor is filled with coal, the most likely ash content in this flow (reference sample with ash previously determined by GOST-11022-64) is equal to: -o) (Cn + Q Ш (L + АI) 4 - (Ca + Q + Q oL - (Cn + s;) c. (I + ij -1 с (с; + Cm + c;) where Cn and Cn are trim tanks; L and L are the reference inductances (see Fig. 1); co and co-fixed frequencies (for example, 3 MHz and 30 MHz), supplying two-terminal generators 1 and 1. And the parameters of the modulating elements (LM, LM, CM and C) are chosen from the condition + 1 ") С„ 1. (3) + ShS „| when the deviation of C (and in the other two-terminal C,) during passage through the angle flow sensor of unknown ash content equality (1) and (2) are disturbed and at the output of each two-terminal high-frequency oscillations of the supply voltage begin to be modulated in amplitude with the switching frequency of the switch (e.g. 50 Hz In this case, the modulation depth of each frequency is determined by the magnitude of the increments Cx and Cd, respectively, in turn, uniquely determined by the increments of the dielectric constant of the sample (it should be borne in mind that the increments e, about the coal selected at the ash frequency change at both frequencies will be of the same sign, but different in size, and the increment share of the mixture 6 brought about by changing the moisture content (humidity) at both frequencies will be the same due to the independence of water from frequency up to 10 MHz). The modulated high frequency oscillation envelopes are detected by detectors 2 and 2 and amplified by amplifiers 3 and 3 with the same force coefficients. At the output of subtraction device 4, a signal sequence is obtained corresponding to the fluctuation of the ash content of the coal in the stream passing through the sensor. The signal averaged by filter 5 (for example, by a "moving average") is fed to a recording device 6 or directly to the control system of the processing apparatus. Switching switches 7 and 7 can be made in the contactless version (for example on diode keys). Object of the Invention A device for measuring coal ash in a stream of dielectric constant at two frequencies, comprising a capacitive sensor, RF generators, detectors, amplifiers, a comparison circuit and a recording device, characterized in that, in order to achieve continuous measurement under conditions of variable material moisture and active losses, it uses a differential capacitive sensor, and as a load a passive RLC two-port network with a pair connected is connected to each of the generators It is appropriate for the sensor to have a switch, to one output of which the inductance is connected, and to the other - capacitance, and the output of the comparison circuit is connected to the recording device through an averaging filter.