RU2281237C2 - Metered powder distribution method - Google Patents

Abstract

FIELD: powder material distribution, particularly to supply powders liable to bridge-forming in metallurgical, building, chemical, food, pharmaceutical and other industries.

SUBSTANCE: method for powder distribution with the use of chamber feeding means involves supplying air in powder bed located in feeding means in jets with alternating speeds so that each next jet has trajectory other than that of previous one. Air is preliminarily dried and has temperature equal to environment temperature.

EFFECT: increased performance and powder material metering accuracy.

1 tbl, 1 ex

Description

The invention relates to the field of methods for dispensing bulk materials, prone to arch formation, and can find application in the construction, metallurgical, food, pharmaceutical, chemical and other industries.

The closest technical solution to the proposed is a method of unloading low-flowing materials [ed. St. USSR No. 1763325, B 65 D 88/70, 1992], including the release of material from the hopper through a cylindrical estrus and the tangential supply of a gaseous agent to the inner surface of the estrus and the hopper, the supply of liquefied gas to the discharge zone.

The disadvantages of this method include the following: dusting of material in the discharge zone, a significant specific gas flow rate, abrasion of the material, entrainment of the finely divided part of the bulk material with a gas stream, uneven discharge of bulk material.

The proposed technical solution allows to increase the productivity of the process of dispensing bulk materials, prone to arch formation, to exclude the formation of stagnant zones in the feeder, to ensure the required accuracy of powder dispensing.

This is achieved by the fact that in the proposed method, which includes supplying air to the powder layer located in the feeder, the air is supplied by jets alternately at different speeds. The trajectory of the jet does not repeat the trajectory of the previous and subsequent jets. The air is supplied pre-drained with an ambient temperature and a relative humidity of 10-40%.

The use of air introduced into the powder layer contributes to the destruction of the arches in the material due to its loosening and constant mixing. Alternating air supply with jets at different speeds and different paths provides vibration in the powder layer and more complete destruction of the arches in the housing and rotor of the feeder. The use of dried air eliminates the formation of condensate in the dosed material.

The method is as follows.

A powder layer with a particle size of 1 μm to 100 μm and above, located in the feeder, is supplied with air pre-dried to a moisture content of less air with ambient temperature. Air is supplied by jets at a speed of ~ 0.1 to 100 m / s, depending on the physicomechanical properties of the powder.

Example. An initial powder, for example, cellulose powder, with a particle size of 5 μm to 80 μm and a moisture content of 8% is poured into a hopper with a volume of 0.01 m ³ , the feeder drive is switched on (the working volume of the feeder is 0.0004 m ³ ) and air is supplied with jets with speed (1.2-1.5) m / s into the powder layer entering the feeder, ensuring its saturation with air, which increases the porosity of the powder from 0.33 to (0.40-0.45) and improves its flowability. Air is supplied through openings located in the wall of the housing of the feeder or rotor of the feeder, the air supply speed is ~ 1.2 m / s, then ~ 1.5 m / s, and the jet path changes due to the use of rotary nozzles installed in the holes. The air velocity is periodically changed by a valve, which creates a vibration in the powder layer. Air temperature 18 ° С, relative humidity 30%. The capacity of the feeder without air supply is 0.098 kg / s, with a pulsed air supply - 0.112 kg / s. The pulsations of the material flow in the feeder do not exceed 10%.

In the known method, the bulk material is dosed by feeding a tangential gas stream through the walls of the hopper and estrus into the material layer, which results in a large amount of fines (solid particles smaller than 10 microns in size), significant gas consumption and insufficient metering accuracy of highly dispersed and wet materials. The values of the process parameters and the characteristics of the proposed method of dispensing in comparison with the prototype are presented in the table.

Table
Characterization of dosing methods. Process parameters Known method The proposed method Specific gas consumption, kg / kg 1.9 · 10 ^-3 0.7 · 10 ^-3 Gas temperature, ° С twenty twenty The relative humidity of the gas,% 75 thirty Critical diameter of the part; dosed material, microns 120 from 1 to 5 Powder Dosing Accuracy,% 55 10 The dust content in the exhaust gas, mg / l 800 fifty The moisture content in the dosed material,% less than 10 up to 25

Using the proposed method for dispensing powders provides, compared with existing methods, an increase in the accuracy of the dispensing process several times. The method is used to obtain mixed compositions in the production of energy-saturated materials.

Claims (3)

1. A method of dispensing powders prone to arch formation using a chamber feeder, comprising supplying air to the collapse, characterized in that the air is supplied to the powder layer in the feeder by jets alternately at different speeds. 2. The method of dispensing powders according to claim 1, characterized in that the path of the jet does not repeat the path of the previous and subsequent jets. 3. The method of dispensing powders according to claim 1, characterized in that the air is supplied pre-dried with ambient temperature.