SU1747202A1 - Method of separation of powdery material - Google Patents

Abstract

Usage: the invention relates to the separation of bulk materials. The invention consists in the separation of material in a vertical separation channel with walls heated to different temperatures. The source material is fed from below into channel 1 with separation zones 2-4, the temperature of which decreases along the height of the channel. 1 з p. F-ly, 1 ill., F tab.

Description

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The invention relates to a technique for separating powdered materials into fractions and can be used in the chemical industry, the industry of building materials, ferrous and ferrous metallurgy.

To sort powdered materials that are larger than 1 mm, vzdushnuyu separation or hydraulic classification is used. In many cases, despite the high efficiency of the hydraulic classification, air separation is used, eliminating clogging of the equipment with wet dust, the need to isolate and dry the separated solid fraction, etc.

There is a known method for separating powdered material in which gas with particles suspended in it is fed to the lower part of the vertical channel, and the fraction of material is taken at the inlet and outlet of the channel. The method is easy to implement. It does not require large areas.

However, the amount of fractions recovered when using this method is only two (top and bottom product). In addition, additional efforts are required to separate the top product from the gas stream, which can be achieved with the help of some precipitation apparatus.

The closest to the proposed technical essence is a method of separating powdered material, including the supply of gas-powder mixture from the bottom up to the separation channel, divided into separation zones, and the output of the separated fractions at the boundaries of the separation zones.

The known method is based on the inertial separation of the powder by size and can not be used in the classification of fine and fine powders due to the small mass of particles and the possibility of trapping large particles of smaller ones. The purpose of the invention is to increase the separation efficiency.

The goal is achieved by the method of separation of powdered material, including the supply of gas-powder mixture from the bottom up to the separation channel divided into separation zones, and the output of the separated fractions at the boundaries of the separation zones, the walls of the separation channel are cooled, in each subsequent upstream zone of separation The separation channel is cooled to a lower temperature than in the previous zone.

In addition, the gas-powder mixture can be heated along the length of the separation

channel, with each subsequent separation zone, the mixture is heated to a higher temperature than in the previous separation zone.

Distinctive features of the method

cooling of the walls of the separation channel, cooling of the wall of the separation channel in each subsequent upstream zone to a lower

0 temperature than in the previous separation zone, heating the gas-powder mixture along the length of the separation channel, heating the mixture in each subsequent upstream separation zone to a higher

5 temperature than in the previous separation zone.

The drawing shows a device for implementing the proposed method.

The method is carried out as follows.

Gao with a powdered material suspended in it is fed to the lower part of the vertical channel 1. Divided, for example, into three cooled zones 2-4.

5 Cooling can be carried out with water, salt solutions, liquid nitrogen. As the gas moves along the channel, solid particles due to the appearance of thermophoresis and microvortices at the channel walls move from

0 core gas flow to its periphery. The selection of the phase water fractions is carried out at the boundaries of channel 1 and at the interface between zones 2 and 3, as well as 3 and 4.

PREMIER Experimental studies of the separation process of a powdery material with a size of 0.1-100 µm are carried out at a gas temperature of 250 ° C and a dust content of 50 g / m3. The consumption of flue gas is 50 m / h. Channel diameter is 0.2 m,

0 channel height 1.5 m, number of sections 3.

The research results are given in the table.

To isolate particles as small as 10 microns when implementing a known method

5 requires the use of an additional precipitation apparatus.

Heating the gas in the core of the flow by means of electric heaters 5 allows to increase the gas flow rate up to 80 m / h,

0 The proposed method is based on the phenomenon of thermophoresis and a change in the gas flow regime in the boundary sublayer (near the channel walls). In thermophoresis, gas molecules come into contact with a hotter body,

5 acquire greater speed and with a greater force act on the particles suspended by the gas flow, their movement from the core of the hot gas flow to its periphery bounded by cold g-angs. Here the pelvic mole is cooled, its viscosity increases, the velocity of the solid particles slows down and the latter, due to Brownian motion, tend to reach the cold wall. Thus, the temperature gradient between the hot gas and the cold walls of the channel contributes to the separation of solid particles from the gas from the flow core to its periphery. Under the action of the translational motion of the gas flow and microvortexes occurring at the channel walls, dust particles move along the cold walls and, reaching the upper edge of the channel, are thrown out of its limits and deposited in the accumulator. The time of transition of particles from the flow core to its periphery depends, other things being equal, on the size of the particles — the larger the size, the longer the specified time. Therefore, using a channel divided by annular gaps into sections, it is possible to select various Fractions. The separation effect increases significantly with the provision of different temperatures in the walls of this zone (for example, decreasing along the channel height) or with additional heating of the haray flow core (for example, increasing along the channel height), which increases the temperature gradient PO of the channel radius, and therefore process strength.

The use of the proposed method provides a satisfactory size separation of the powdered material, and the device for its implementation is simple in execution. In addition, the method can be used for ordinary gas cleaning from dust.

Claims (2)

1. A method for separating powdered material, including supplying a gas-powder mixture from bottom to top in a separation channel divided into separation zones and outputting separated fractions at the boundaries of the separation zone, characterized in that, in order to increase the separation efficiency, the walls of the separation channel are cooled , in each subsequent upstream separation zone, the walls of the separation channel are cooled to a lower temperature than in the previous separation zone. 2. A method according to claim 1, characterized in that the gas-powder mixture is heated along the length of the separation channel, with the mixture being heated to a higher temperature in each subsequent upstream separation zone than in the previous separation zone.