SU954742A1 - Method of drying pulverulent materials - Google Patents

Description

one

The invention relates to a drying technique and can be used in the food, medical, chemical and other industries of the industry for the deep drying of heat-sensitive, dusty, sintering and combining materials.

The known method of drying dispersed materials by repeated repetition of the heating-vacuum cycle with increasing vacuum depth from cycle to cycle when heated in a high-frequency field or infrared rays 1,

The disadvantage of this method is the possibility of sintering the Material.

There is also known a method of drying dispersed materials by alternating alternating heating, vacuuming and shaking the layers of materials. The layer is shaken by fluidization of the layer of material released from the material

water vapor during pulsating vacuum 23.

The disadvantage of this method is the low efficiency of shaking the material during the period of falling drying speed and the possibility of sintering. no material during this period, which leads to a deterioration in its quality.

The purpose of inventions is to improve the quality of drying.

ten

This goal is achieved by shaking the layer of material by abruptly communicating the underlayer space with the atmosphere.

15

Figure 1 shows schematically an installation for carrying out the proposed method; figure 2 - section aa in figure 1.

The installation contains a cylindrical

20 a vacuum drying chamber 1 with a grid 2 on which the material to be dried 3 is placed. From the outside of the chamber 1 there are plates 33 of a condenser designed to heat the material 3 with high frequency. In the lower part of the drying chamber there is a valve 5, intended for sharp depressurization of chamber 1. In the upper part of chamber 1 there is a valve 6, through which it is connected to a vacuum pump. In the upper part of chamber 1 above the layer of material 3 a barrier 7 is installed in the form of diametrically divided knives. The installation works as follows. The wet material 3 is placed in a drying chamber 1 on a grid 2 and heated for a predetermined time with a condenser k. Heating is then stopped and the chamber is evacuated through valve 6 to a predetermined pressure. After the evacuation stage, the underlayer space is made with atmosphere by means of valve 5. The pressure difference created under the layer and above the layer of material 3 causes the layer to produce a piston pressure, as a result of which it collapses. Especially good results are obtained if obstacles 7 in the form of knives are in the way of the layer movement, which produce additional destruction of the layer with the mixing of material 3. Then the cycle repeats. Example. The pyrotechnic composition is dried on a volatile solvent with an initial humidity of 6.5% at a height of layer hQ mm. The required final moisture content in the material after drying is 0.65%. The dried material must be free-flowing and have a grain size of 5-1 mm. The material placed in the chamber 1 on the grid 2 is heated to 70С with the help of the condenser k. Then the chamber is evacuated. During the tests, the vacuum depth from cycle to cycle is increased from 10 to 50 Pa, which corresponds to the change in the pressure difference in the environment and the drying chamber 8.806610-E.botb-Yu Pa. After the evacuation stage, the underlayer space is abruptly communicated with the atmosphere by means of valve 5. The cycle is then repeated. The test results are summarized in table.

Carrying out the drying process according to the proposed method allows to obtain a higher quality material by shaking the layer after the evacuation stage, especially good results are obtained with the use of a barrier, which eliminates the need for product granulation.

Formula I of the Inventory Drying of dispersed materials by alternating alternately heating, evacuating and shaking a layer of material, characterized in that, in order to improve the quality of drying, shaking of the layer is accomplished by abruptly communicating the underlayer space with the atmosphere. Sources of information taken into account in the examination

Fin 2 1. Authors certificate of the USSR №, cl. F 26 B 5/01, 1978. 2. The USSR author's certificate in accordance with application number 2139699, cl. F 2b 3/08, 1976.

Claims (1)

A method of drying dispersed materials by repeatedly alternating heating, evacuating and shaking a layer of material, characterized in that, in order to improve the quality of drying, shaking the layer is carried out | They are created by abrupt communication of the sublayer space with the atmosphere.