SU1242754A1 - Method of measuring density of loose materials - Google Patents

Abstract

The invention relates to methods for measuring the density of a bulk material, material and can be used, for example, in the radio industry to control the charge in the manufacture of ceramic products. The purpose of the invention is to increase the accuracy of density measurement. The method consists in that the bulk material, previously subjected to vibration, in the vibrocavity mode, is passed with a previously calculated flow rate through a capacitive sensor and the dielectric constant is determined before and after the introduction of the conductive powder of a known concentration and. the magnitude and variation of the dielectric constant and the known density of the conductive powder are judged on the density of the bulk material. 1 ill., I table. (L N9 -h | el

Description

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The invention relates to a technique for measuring the density of bulk materials and can be used in radio engineering enterprises, for example, to control the quality of the charge in the manufacture of ceramic products.

The aim of the invention is to improve the accuracy of measuring the density of bulk materials.

The drawing shows a device for implementing the method.

The device comprises a hopper I, patch electrodes 2 and 3, a recording device 4, a mushroom table 5 and a vibrator 6.

To implement the method, the following operations are carried out: the bulk material is weighed, loaded into a bunker, and vibrated in a vibrating mode, mixing its particles at a flow rate equal to nusho. Brought to vibro-fluid state.

Pass the bulk material in a vibro-liquefied state through a capacitive sensor, provided that the flow

G KQ / f, (1)

where G is the flow rate, kg / s;

K (0.5-1) 10 is a coefficient depending on the dispersion of the bulk material

Q is the volume of the capacitive sensor, m f is the frequency of vibrational oscillations of particles of the bulk material, Hz, and the dielectric viscosity of the bulk material is measured.

Add in the range of 5–15% by weight of conductive powder to the bulk material, selecting the maximum particle diameter of the powder less than half the average particle diameter of the bulk material and ala. The bulk material is mixed with the addition of conductive powder in a vibro-peak mode and a flow rate equal to zero. The bulk material is passed again in a vibro-fluidized state through a capacitive sensor at a flow rate G KQ / and the dielectric constant E of the bulk material containing the conductive powder is measured.

According to the known dielectric permeability, and E. to the relative, concentration of the conductive powder, the density of the bulk material is determined by the formula

five

 I dp (d

d

May

q

five

0

five

0

five

- l) (7th;), (2)

where d is the density of the bulk mother.,} la, kg / m;

 - apparent with (or material)

density of conductive powder. Kk K1 / m;

the relative mass concentration of conductive powder in the bulk material; - the relative dielectric constant of the bulk material before and after the introduction of the conductive powder. In order to increase the increment of di-ele-tr: permeability, the relative mass concentration is chosen-. maximally possible in the range of 0.05-0.15 (5-15 wt.%), taking into account the density of the bulk material so that the volume concentration does not exceed 0.2 (when excess1; the tone of the persistent conductive powder begins change the volume of bulk material being measured). For lightweight bulk materials such as ash, this limit occurs at 15% conductive powder in the ash, for heavy ones (such as nickel oxide) - at 5% by weight.

Example 1. A river sand density measurement is carried out with an average particle size of 0.2 1 F1 on a capacitive sensor consisting of a bunker in the form of a vertical quartz tube 1 with a diameter of 20 mm and a height of 100 mm with superimposed electrodes 2 and 3 of copper foil connected to a recording device 4 of type P-589, and a mushroom-shaped steel table 5, 24 mm in diameter, with an adjustable gap by screw thread on its leg, as well as a vibrator 6 mechanically rigidly connected to tube 1 and table 5 by means of an arm “

The vibrator 6 is assembled on a DPM micromotor - 20 HI-O, 4, on a shaft with eccentricity radius of 10 mm, an unbalanced load of 1 g is fixed, rigidly fixed on the tube 1 with the shaft parallel to the tube axis. ash particle vibration velocity range from 5 (vibroimage state with minimum viscosity) to 30 m / s (vibratory melting point of the material with mixing of particles) with a change in voltage

Power supply from 5 to 20 V AC (50 Hz). The approximate value of the acceleration of particles is calculated by the formula, measuring the frequency of the engine rotation

. and mro / m

where a is the vibration acceleration of particles, m / s; m - unbalance mass

cargo, kg;

W is the mass of a capacitive sensor, kg;

  unbalance radius, m G} -27i - circular -frequency of rotation of the engine, rad / s.

At the aforementioned dimensions of the element of the vibrator, the vibro-liquefaction state with the minimum viscosity (a 5 m / s is observed at a rotational speed of 300 rad / s, and vibro-dropping (a 30 m / s2) is 735 rad / s.

The sand loaded into the bunker is kept in a vibro-peeling mode for 1 minute, the vibrator is switched to the I mode corresponding to the vibro-fluid state of the sand, and the i-gap is opened so that it is more than twice the size of sand particles (0.2 mm), but less than half the radius, and equal to

r4

kg / s, which satisfies the conditions

VIS (1).

The recording device 4 can be directly calibrated in dielectric constants by pre-filling the capacitive sensor with liquids with known dielectric constants (kerosene, 2.1 and t, e.) Or calculated using an empirical formula. For example, for the proposed capacitive sensor

 (7.4 С - 16) / (1b - С), (3)

where C is the capacitance between the electrodes 2 and 3.

As a conductive powder, coke is used with an apparent density of 760 kg / s Ad and a maximum particle diameter of 0 mm.

According to the reference bulk density of sand, d 1600–2200 kg / m, estimate the permissible mass concentration dggp 0, ido / d (0.07–0.1, take the value. 0.05, which guarantees the accuracy of the measurements.

15

20

427544

The results of measurements and calculation of the density of sand are presented in the table.

Example 2. The measurement of the density of the ash of the ash of boiler boilers (bulk density d 1000 kg / m) is carried out. The average particle size is 40 microns. Therefore, it is convenient to use carbon black as a conductive powder, the particles of which are less than 5 microns, and the material density is dg 2000 kg / m. Approximate calculation (0 ,, 0,2 2000/1000) allows to apply the concentration of soot

  .

The result of measuring the density of the zo-ly is listed in the table.

From the description of the method for determining the density of the bulk material, it is obvious that variations in the application of the method are possible.

For example, the sign of the density in the out-of-oxygen state of any

bulk material, it is possible to determine the density of another, even

 not knowing the apparent (or material) density of the conductive powder, which in this case should be the same.

As a conductive powder

30 can use graded and powdered metals. For example, in the production of piezoelectric ceramics in the preparation of the barium titanate charge, it is modified to improve the dielectric properties of 1% by weight metal cobalt, which is oxidized to a cobalt oxide during firing. A slight (less than 5% dose of conductive powder) is quite acceptable,.

0 due to an increase in ch1: the nature of the proposed method with an increase in the dielectric constant of the charge.

Thus, the proposed method for measuring the density of bulk materials improves the accuracy of measuring the density of bulk material by up to 5%, while in the known methods the density depends on the history of sample preparation and ranges from 15%.

Claims (1)

Invention Formula The method of measuring the density of the bulk material, including the preliminary weighing of the material and its vibration in the mode of vibrating foam, characterized by that. what. S1 precision, loose, brought into vibro-liquefaction, is passed through it with a sensor with a flow rate G KQ / f, (О, 5-10) 10 - coefficient, depending on the dispersion of the bulk. material, N / m4; Q is the volume of a capacitive sensor, f is the frequency of oscillations of particles of the bulk material, Hz, river sand coke 2427546 and the dielectric constant is measured, the conductive powder with a relative mass concentration of 5-5-15% is then added to the bulk material, the mixture is stirred in a vibrocake mode, it is passed through a capacitive sensor with the same flow rate, the dielectric constant E is measured and determine the density of bulk 10 d by the formula  (a ;;, -, kg / m where d is the apparent (or material) density of the conductive pellet, kg / m. 4.98 6.69  Jf. Circulation 778 Subscription Spike-poly. pr-tie, Uzhgorod, st. Project, 4