SU1453296A1 - Method of measuring humidity of finely divided granulated material - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is improving the accuracy and stability of moisture measurement. A new method is that the measuring capacitor is first freed from the medium being analyzed and its capacitance is measured, and then during the selection of the bulk material and the filling of the measuring capacitor, its dispersion size is reduced so that the granule size becomes at least two times smaller. distance between the capacitor plates. The difference between the two measurements of the tanks and the temperature of the medium determines the humidity of the analyzed product. The method can be used (A used in the microbiological, food, chemical and other industries of the x / L industry. 1 dw., 1 tab.

Description

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The invention relates to a measurement technique and can be used to automatically control the moisture content of powdered and granular materials in a pneumatic transducer; tailors in the microbiological, food, chemical and other industries.

The purpose of the invention is to improve the accuracy and stability of the moisture measurement.

The drawing shows the structure of the device that implements the proposed method.

The essence of the proposed method for measuring the moisture content of the fine material consists in the following.

The powder or granules transported to the pneumatic conveying lines are periodically selected to fill the measuring capacitor of the capacitive sensor through a grid with calibrated orifices, and then return to the pneumatic conveying line. At the moment of complete emptying of the cuvette from the analyzed medium, the measuring capacitance of the measuring capacitor is measured. The measurement result is a function of both the capacitance value of the measuring capacitor and the magnitude of the conversion factors.

and

you

 f (Co),

(one)

where Ugt, y is the output of the measurement transform; С - capacity of empty con0

densator.

A particular and most common case of conversion is a linear function.

UBUX, k, C ,, (2)

where k, is the capacitor fill factor.

When the measuring capacitor is filled through a grid with calibrated holes, whose diameter is at least two times less than the distance between the capacitor plates, and when compacted, this material achieves a stable uniformity and density of the capacitor, which ensures relative stability and accuracy of humidity measurement. the material re-measures the capacitance. The measurement result can be described by the following expression:

0 5 o

and

Bbivi

five

Q

q q

five

f, CC., + fa (W, f, eJ. (3)

where f (W, f, „) is the increment of the capacitance of the capacitor due to the humidity of the material (W), its density (p) the dielectric properties of the dry material (/“).

A particular case of a linear transformation can be represented by the following expression:

U6t, v2 k, Co-t-k, f (W, p, j (4) The difference between the two dimensions is found

4U f, Co + fi (W, p, M) -fi (Cj (5)

whether f, f2 (W, p, EM) j. (6)

The final transform expression (6) does not contain one of the sources of measurement error f (Cp), which in a number of cases, for example, with Cp7f (W, P /)), can significantly improve the accuracy of the conversion as a whole. Thus, the essence of the method is to reduce the variation in the degree of filling of the capacitor due to artificially reducing the dispersion of the material being analyzed, which allows to increase the stability and accuracy of the measurement.

In addition, measuring the capacitance of the filled and empty measuring capacitor with the subsequent finding of the difference between the two values makes it possible to eliminate the essential element of the conversion error in the process of finding the value of humidity.

A moisture measuring device mounted on the pneumatic transport line 1 includes a grid 2 covering the receiving hopper 3 connected to the measuring capacitor 4, one of the plates of which performs the function of a vibroplate 5 excited by an electromagnet 6. The vibrating plate 5 and the electromagnet 6 functionally form a seal assembly. Via valve 7, air is supplied from the high pressure line 8 to the internal cavity of the condenser 4. The electronic unit 9 is designed to measure the capacitance of the capacitor 4 and form commands to control the valve 7, the electromagnet 6. The diameter of the openings of the grid 2 is at least two times smaller than the distance between the plates of the capacitor 4,

The device works as follows.

When the valve 7 is closed, particles of the fine material moving along line 1 hit the grid 2, partially slip through the holes, get into the hopper 3, and then into the cavity of the measuring capacitor 4. After filling the capacitor 4, the electromagnet 6 activates the vibrating plate 5 and the medium compacted. In block 9, the capacitance of the filled capacitor 4 is measured.

When the valve 7 is open, air from the high pressure line 8 (in some cases directly from the atmosphere) enters the internal cavity of the condenser 4 and blows the analyzed material into line 1, preventing its further penetration through the grid 2. In block 9, a measurement is made empty the capacitor 4, calculate the difference of two measurements and convert it to a signal proportional to the moisture of the material

As an example, the results of measurements of the moisture of the granules are given.

3296

in which the particle size becomes half the distance between the capacitor plates, it significantly reduces the random component of the measurement error.

The application of the proposed method of measuring humidity allows automating the process of controlling the humidity of a number of materials with simple means with high stability and accuracy.

Claims (1)

Invention Formula A method for measuring the moisture content of fine granulated material in a pneumatic conveying line, mainly microbiological synthesis products, which consists in taking a sample of the material in the cuvette of a capacitive capacitor, compacting it, measuring the temperature of the sampled sample and the capacity of the condenser, and then determining the humidity, characterized in that, in order to improve accuracy and stable of a measured protein production product, directly from vitamin-to-vitamin concentrates with the outcome of each measurement of a capacitance with a filled humidity of 7.0 abs.%. 30 capacitors are measured by the capacitance. The same empty capacitor is used for the measurements, and in the process of sampling form the granulometric composition of the material separators with a distance of 4.5 and 3.5 mm between the plates, grids with a diameter. holes 3.2 and 1 mm. The measurement results are shown in the table. Thus, reducing the dispersion of particle size distribution, so that the limiting size of the granules 35 is at least two times smaller than the distance between the plates of the capacitor, and the determination of the humidity is determined by the difference between the capacities of the filled and empty capacitors 3.5 so that the limiting size of the granules 35 is at least two times smaller than the distance between the plates of the capacitor, and the determination of the humidity is determined by the difference between the capacities of the filled and empty capacitors 3 3 6 3