SU949473A1 - Coal ash content checking method - Google Patents

Description

The invention relates to a measuring technique, namely, methods for monitoring the quality parameters of coal preparation products, such as coal ash, and can be widely used to control the ash content of coal preparation products under conditions of coal chemical laboratories, as well as to create automatic ash control devices in the measuring flow of samples taken.

Known radioisotope method for controlling ash ash l.

However, the radioisotope control method is difficult to implement, expensive, and its industrial use is associated with the need to observe special sanitary standards.

Closest to the invention is a method for monitoring the ash content of coal, which consists in measuring the electrical parameters of a sensor with a breakdown located in an electric field of high frequency f.

However, despite the ease of implementation, this method of controlling ash content has not been widely spread due to the low control accuracy.

The purpose of the invention is to increase the accuracy of the control.

The goal is achieved in that according to the method of controlling the ash content of the coal, which involves measuring the electrical parameters of the probe with the probe, the u-Ace is in a high-frequency electric field, the probe is dried to a completely dry state, cooled to a fixed temperature, then a dosing number is entered moisture and measure the capacitance or conductivity of the sensor with a breakdown, the magnitude of which and the calibration schedule is judged to be controlled in size.

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In addition, before introducing a metered amount of moisture into the sample, the capacitance or conductivity of the probe with the probe is measured, and the controlled value is judged by the increment in the capacitance of the probe with the probe or conduction and the calibration curve.

In this case, moisture in the form of fine particles of water, for example,

distilled, injected to a fixed level, not exceeding 1-2%, and fine particles of moisture created by using spray guns or in the form of aerosols using electromechanical humidifiers.

The essence of the proposed method is based on an experimentally established correlation between the capacity and ash content, as well as between conductivity and ash content for completely moistened absolutely dry samples to a fixed level of moisture not exceeding 1-2%. At higher fixed values of moisture, said correlations are insignificant, i.e. are missing.

The presence of a correlation between conductivity and ash content has also been established, and the existence of such a relationship between capacity and ash content for completely dry samples has been confirmed.

The drawing shows the curves of correlation graphs between capacity and ash content.

Example. For the experiment, coal grades G and K of class 0-3 mm were used, the HF field frequency was 200 kHz, the sensor filling volume was 800 ml, and the ash content of the samples changed from b to 37%.

At the same time, samples with working moisture of high grade were tested to constant weight (absolutely dry samples), and then cooled to room temperature.

The correlation between capacity and ash for completely dry samples, such as grade G coal, is shown in Graph 1, and the correlation between conductivity and ash is shown in Graph 2 of the drawing.

Similar correlations for samples forcibly humidified up to 1.2% are shown respectively in Graph 3 and 4 of the drawing.

The conductivity of the sample is judged by the magnitude of the voltage drop across a resistor connected in series with the sample sensor, provided that the voltage of the RF generator is constant. The resistance value of the resistor is chosen approximately an order of magnitude less than the active resistance of the sensor with the sample.

In this case, the metered introduction of moisture in the form of fine particles of distilled water is carried out with the help of sprayers or in the form of aerosols with the help of electromechanical humidifiers.

Drying the sample, as well as the subsequent dosed introduction of moisture, the S sample allows one to completely eliminate the influence of moisture as an interfering factor on the accuracy of control. ash content in both capacity and sample conductivity. In addition, the introduction of a fixed value of moisture into the sample also makes it possible to increase the sensitivity of these methods.

The sensitivity of the method, both in capacity and in conductivity of the sample, increases with the introduction of 1.2% moisture (distilled water), for example, at the end of the controlled

range of ash content, approximately twice (drawing).

The effect of active sample loss in this case is also minimized, since the addition of moisture is

0 a small amount slightly changes the active resistance of the sample, (by about 20-30%), compared to absolutely dry samples of the same ash content, moreover, absolute

5, the active resistance value in this case is calculated in tens of kOhms.

The latter allows to obtain a high quality factor (30-120) of measuring resonant circuits and simplify the implementation of, for example, the capacitive method.

Experimental studies have established that between increments

5 capacity, as well as the increment of conductivity with the metered introduction of moisture into the sample in relation to absolutely dry samples and ash. Sample also exists correlation

Q bond (calibration curves 5 and 6).

Drying of the sample under real conditions is carried out using accelerated methods, for example, using RF and microwave methods, which takes 3-5 minutes. Cooling of the sample is carried out by such well-known methods as, for example, by a thermal path or by natural cooling in a desiccator, which takes 3-10 minutes.

Calibration curves are plotted on

Q Based on the calculation equation, which is obtained by preliminary measurement of the proposed method. Samples with known ash content (found according to GOST 11022-75) and processing the obtained data.

The calculation equation is used to automatically determine the ash content of coal samples with a previously unknown ash content, for which

0 requires a simple calculating device ..

The invention makes it possible to increase the accuracy of controlling the ash content of coal by high-frequency methods (capacitive and sample conductivity), since it eliminates the influence on the control result of the main interfering factors of humidity and active sample loss.

In addition, the proposed method 0 allows at least twice

increase the sensitivity of ash content determination both in terms of capacity and sample conductivity.

Compared with the conventional thermosomal control method (GOST, 11022-75)

Claims (3)

Claim 1. A method for controlling the ash content of coal, which consists in measuring the electrical parameters of a sensor with a sample! 5 located in a high-frequency electric field, characterized in that, in order to increase the accuracy of control, the sample is dried to an absolutely dry state, cooled, a fixed temperature, then a dosed amount of moisture is introduced into the sample and the capacitance or conductivity of the sensor is measured with a sample, the magnitude of which and the calibration curve are used to judge the controlled value. moisture measure the capacitance or conductivity of the sensor with a breakdown and, according to the magnitude of the increment of the capacitance with the conductivity of the sensor with a breakdown and the calibration schedule, judge about a controlled value. 3. The method according to PP.1 and 2, characterized in that the moisture in. in the form of fine particles of water, for example, distilled, is introduced. to a fixed level of moisture not exceeding 1-2%. 4. The method according to claims 1 to 3, characterized in that the fine particles of moisture are created using spray guns or in the form of aerosols using electromechanical humidifiers.