SU1237955A1 - Method and apparatus for measuring concentration of particles of dust-gas medium - Google Patents

Abstract

The method of measuring the concentration of particles of the dust-gas medium and the device for its implementation can be used in the mining, metallurgical and other industries. The purpose of the invention is to improve the measurement accuracy and expand the range of sizes of the planned CO with CO: l | SL

Description

particles by providing an auto-calibration mode and reducing the number of registered parameters. The dust-gas medium is accelerated in the mixing chamber 1 by ejecting gas flowing out of the nozzle 2 with known values of density and dynamic head. In this case, a clean gas having the same density as the ejecting gas is preliminarily accelerated in the chamber, and the static pressure on the chamber wall is measured outside the gas mixing region. The gradient dependence of accuracy — pressure — is determined, and when measuring the concentration of the analyzed particles, the static pressure is kept constant.

The invention relates to a measurement technique, is intended to measure the concentration of particles suspended in a gaseous medium, and can be used in the mining, metallurgical and other industries.

The aim of the invention is to noBbmie the accuracy of measurement and the expansion of the size range of the analyzed particles by providing an auto-calibration mode and reducing the number of recorded parameters.

The drawing shows the functional scheme of the device for implementing the method.

The device comprises an ejector with a mixing chamber 1, made in the form of a Venturi tube with an elongated cylindrical neck, and a nozzle 2 connected to the output of the pressure regulator 3 with the second inlet of the pneumatic diaphragm 4. The output of the adder 4 is connected via throttle divider 5 to the recorder 6 pressure. The input of the regulator 3 and the first input of the adder 4 are connected to the opening 7 in the wall of the chamber outside the gas mixing region. The choke divider is installed according to the results of autocalibration with the help of drossel with adjustable conductivity in the position

The device contains an ejector with mixing chamber 1 and nozzle 2, the inlet of which is connected to the outlet of pressure regulator 3. The inlet of pressure regulator 3 and the first inlet of adder D are connected to a hole 7 made in the wall of chamber 1 located outside the area of gas mixing. The second input of the adder 4 is connected to the output of the pressure regulator 3, and the output of the adder 4 through the throttle divider 5 is connected to the pressure recorder 6, the ratio of the throttle divider arms is determined by the steepness of the calibration curve. 2 sec. f-ly, I ill.

where the following relationship holds:

(), (I)

where Y-, 1b - the performance of choke divider, respectively; K is the steepness of the calibration characteristic.

The controller 3 and the adder 4 are supplied with compressed gas, for example, clean air. The controller 3 has an input for setting the value of the adjustable parameter.

The method is carried out using devices. As follows.

The ejector with the mixing chamber 1 and the nozzle 2 is pre-immersed in a gas of the same density as the ejector, such as atmospheric air, and the static pressure on the wall of the chamber is measured before mixing with the aid of the aperture 7 when the ejecting gas flows out of the nozzle 2. The value of this pressure, equal to the dynamic head of the passive gas, is set at the inlet of the setting of the 3 P regulator, p, V // 2 (2) with an accuracy of the hydraulic resistance coefficient of the input of the mixing chamber 1, which, with a smooth entrance of the Venturi tube, where p and V are, respectively, the density and velocity of the jet of a passive gas at the entrance to the mixing chamber.

The pressure in front of the nozzle associated with the dynamic pressure of the ejecting gas is expressed by the known ratio

, vf / 2, (3) 5

where Y is the hydraulic resistance coefficient of the nozzle;

О ,, V is density accordingly

and the velocity of the jet ejecting gas.

Given the ratio for the ejection ratio

, V, F // () iV2F2 (4) It is possible to obtain the equation of the calibration dependence in dimensionless coordinates, density - pressure

p2 / P - {n F / F / p (P, / P), j5) where F, and Fj is the area of the transverse

sections at the inlet to the mixing chamber for the jet 20 ez. of the exciter and passive gases, respectively. In the atmosphere, the density is one. 55

Therefore, the slope K of the calibration characteristic can be found in relation to the dynamic pressures of the passive and ejecting gases, or taking into account the hydraulic resistance of the nozzle by the pressure in front of the nozzle 30 / P. (6)

The pressure in front of the nozzle must be read out from the static pressure after the nozzle — this subtraction operation is performed by adder 4, at output 35 of which the throttle divider 5 sets the obtained slope value in accordance with the expression (l) so that the readings of the recorder 6 correspond to 40 were of unit density.

This is the auto-calibration procedure.

Then, the ejector is immersed in the test pyazegas medium and the regulator 45 maintains the static pressure equal to its values in the atmosphere, then the pressure in front of the nozzle 2, measured from the static pressure in the nozzle section 2 by adder 4 and fixed by the recorder 6 taking into account the slope the formula (6), set on the divider 5, is proportional to the density of the dust-and-gas medium relative to the air density according to the calibration dependence (5)

Registrar 6 is calibrated in units of unlimited concentration, for

the density scale is shifted by one.

Since the dusting of the elements of the ejector changes the relation (5) as well as abrasive wear, it is advisable to perform the autocalibration by periodically transferring the ejector from the dust-gas medium to the atmosphere without removing the drained sediment on the structural elements.

The autocalibration frequency is determined by the operating conditions.

Claims (2)

Invention Formula I. A method for measuring the concentration of particles of the dust-gas medium, in which the dust-gas medium in the mixing chamber is accelerated by an ejecting gas flowing from the nozzle with known values of density and dynamic head, characterized in that in order to increase the accuracy of measurement and expand the size range of the analyzed particles By providing an autocalibration mode and reducing the number of parameters to be recorded, a clean gas pre-accelerated in the chamber, having the same density as the ejection, measures the static pressure per second. The chamber is outside the gas mixing region, the gradient of the density-pressure calibration is determined, and when the concentration of the analyzed particles is changed, the static pressure is kept constant and equal to that obtained by graduation by changing the flow rate of the ejecting gas, while the particle concentration is determined by the dynamic pressure of the ejecting gas. gas and gradient graduation. 2. A device for measuring the concentration of particles of the dust-gas medium, containing an ejector with a displacement chamber and a nozzle, the inlet of which is connected to the output of the pressure regulator, and a pressure recorder, so that, in order to increase - neither the accuracy of measurement and expansion of the size range of the analyzed particles by ensuring the autocalibration mode and reducing the number of recorded parameters; the device is equipped with a pneumatic adder, the first input of which and the input of the pressure regulator are connected to the orifice filled in Tenke camera raspolozhen512379556 outside the gas mixing zone, the second divider is connected to the registrar, the second input is connected to the output of the pressure regulator, and the ratio of the arms l torus pressure, output of adder of throttle divider is determined the cut entered into the device of the throttle is the steepness of the calibration dependence.