SU878356A2 - Pneumatic classifier - Google Patents

Description

(54) PNEUMATIC CLASSIFIER

one

The invention relates to the field of pneumatic classification of various bulk raw materials in a horizontal air flow and is intended for dividing a material with a size up to 20 mm into two or more products.

From the main auth. St. No. 753491 is known for a pneumatic classifier that includes a separation chamber with loading and unloading devices, inside of which there is a louvered grating under the loading nozzle at an angle to the horizon, the upper part of the grating being rigidly fixed and the angle of inclination is determined by the formula:

tg -l. .one

3; (tt7 - IP,) - -v acceleration of free fall,

where g

0.5- grain boundary size, m;

W — medium flow rate, m / s;

Wf. - speed of movement of grain of the boundary size, m / s; the proportion of material

Tr density of the medium

TCP resistance coefficient. In contrast to similar classifiers, this apparatus homogenizes the air flow immediately before the interaction with the material being classified. Installing the lattice at a certain angle helps to improve the efficiency of material classification by eliminating the difference in heights of the beginning of the interaction of monofraction with a continuous medium.

The disadvantage of the classifier is

10 poor separation quality at elevated material concentrations (kg / m). This is due both to the uneven distribution of the material over the cross section of the separation chamber, and to an increase in the density of the layer of the initial mixture moving along the grid.

Due to the increase in the quantity of the mixture, the hydraulic resistance of the layer of material dramatically increases, this. 20 leads to a violation of the uniform flow of material particles around the air stream and, as a consequence, an increase in the number of small particles in a large product.

The purpose of the invention is to increase the efficiency of classification and increase the productivity of the apparatus due to a more even distribution of the layer of material on the louvered grille.

The goal is achieved by the fact that the classifier is equipped with reflective plates.

installed but louvered grille parallel to each other at an angle to the grid from 20 to 30 °.

A louvre-type grille is positioned so that its upper part is directly under the nozzle of the initial material into the separator. The angle of inclination of the lattice depends on the type of material being classified and is determined by the known formula.

The reflective plates are fixed on the lattice parallel to each other iodine angle to the plane of the lattice and have a width equal to the width of the separator chamber. The angle of inclination of the plates is determined experimentally and is the most extreme. Placing the plates at an angle of more than 30 ° leads to the fact that the material is not reflected by the plates, but is delayed by them, which reduces the quality of the separation. The installation of reflective plates with an angle of less than 20 ° also leads to a decrease in the quality of separation, since the material is not sufficiently loosened and therefore unevenly blown by the air flow.

Reflective nlastins are designed to increase the porosity of the layer of material, and together with the grating they also contribute to a more uniform distribution of the material and the cross section of the apparatus.

The grid has a sufficiently large (not less than 100 mm water column) hydraulic resistance, which makes it possible to maintain a constant mode of motion of the medium over the entire height of the chamber.

Thus, equalizing the air flow rates across the cross section of the separation channel, uniform distribution of the solid phase over the cross section of the apparatus, and increasing the porosity of the material layer can significantly improve the quality of separation and increase the productivity of the apparatus.

FIG. 1 shows the classifier, a general view; in fig. 2 - diagram of the connection of the classifier with cycloi and fan.

The classifier consists of a rectangular case 1, in the upper part of which there is a nozzle 2 for feeding the source material into the separation chamber. A distribution grid 5 with reflective plates 4 is located under the branch pipe. The upper part of the grid is fixed directly under the branch pipe of the inlet 2, the lower part of the grid is connected to bunkers 5 for collecting separation products.

The material is loaded into the apparatus, as well as the discharge of separation products is carried out through sluice feeders 6, ensuring that the chamber of the apparatus is sealed on the loading and unloading side of the material. Air enters the separator through the side window 7. The flange 8 separates the separation chamber with the cyclone to trap the dust fractions.

An example of a specific implementation of a distribution grid with reflective plates is shown in FIG. 1, node I. The lattice consists of profiled

rods 9. The upper rod is installed directly below the pipe for feeding the starting material. Subsequent rods are mixed relative to each other with a gap equal to half the cross section of the rod.

Rod length / i 4,5 in. Such a structure provides the necessary hydraulic resistance of the grid. The plane of the rod, which moves the material, is inclined to the horizon at an angle,

equal to the angle of inclination of the lattice itself. Regarding the air flow, the rods are located with a zero angle of attack, which is the best option and ensures the free flow of air through the grid without the formation of turbulence after the rods, slightly deforming the air flow. The front face of the rod is made along a cylindrical generatrix with a radius equal to half the width of the cross section -, L

NIN Rod / what provides

Calm, without disturbances, the flow entrance into the lattice slits.

The installation additionally includes a cyclone 10 connected via a spigot // to the fan 12. The reflective plates are arranged across the entire width of the separation chamber parallel to each other under

angle of 20-30 ° to the grating plane and have a length of / 2, equal to 56.

Classifier works as follows.

When the fan 12 is turned on, a horizontal air flow is created in the separation chamber of the classifier. The source material is fed by the feeder through the inlet 2 to the distribution

grid 3 separators. The flow of material is blown with air and gradually, moving along the plane of the grating, falls on the reflective plates, where it is removed from the grating. When falling from reflective plates, the flow of material is loosened and is therefore more intensively wound with air. Due to the air, the grating and the baffle plates, the distribution and intensive blow-down occurs.

material flow, which allows the entire volume of the separation chamber to be used for material separation.

Dust particles together with the air flow from the apparatus into the cyclone 10,

lde are collected from the air, collected in

cyclone hopper and discharged through a floodgate. The cleaned air enters the suction nozzle of the fan 12. The air flow rate in the separation chamber of the classifier is controlled by the hook 11.

The unit operates under pressure, which eliminates dust emission into the environment.

With the same dimensions of the prototype and the proposed classifier, the productivity of the source material increases by 2-3 times due to an increase in the expenditure concentration of the material, while increasing the separation efficiency by -15%.

Claims (1)

1. USSR author's certificate No. 753491, cl. B 07 B 4/08, 1978. 41 Jdifl., // ff I