RU2598091C2 - Drying method of pellet powder - Google Patents

Abstract

FIELD: technological processes; weapons and ammunition.

SUBSTANCE: invention relates to production of spherical powders (SP) for small arms, namely to powder drying. For drying powder with moisture content of 18-22 wt% and graphite is fed via settling cyclone in continuously acting fixed drier, in lower part of which there is a box, divided into three sections for supply of heat carrier. On top of the box in the inner part of the drier grid is installed to create air pressure under screens. On each side of the box is installed in vertical plane at an angle of the wall with blow-out surface. In the first section the powder is dried at air temperature 93±5 °C, in the second section at temperature 70±5 °C, and in the third - 50-60 °C. Drying is performed in boiling conditions. Height of boiling layer powder on the screen is controlled by separation grids. Boiling layer on the screen move due to difference of air supply to the section of the box. Common drying cycle 1.0-2.5 h, efficiency of the dryer 200-300 kg/h at moisture content of dry powder 0.3-0.9 wt%.

EFFECT: method provides safe and effective drying of powder and production of powder with preset physical and chemical properties with minimum labor costs and power consumption.

1 cl, 1 dwg, 1 tbl, 5 ex

Description

The invention relates to the field of production of spherical powders (TFP) for small arms.

In the literature [1] there are known methods of drying various materials, including bulk in a boiling gushing mode. However, the known drying methods are unacceptable for drying TFP due to the high sensitivity to temperature effects.

Currently, spherical gunpowder for small arms is prepared as follows: ~ 4 parts of water are poured into a semi-industrial and industrial type reactor with respect to one part of pyroxylin or powder mass, mixing is carried out for 15 ... 20 minutes. Then ~ 4 parts of ethyl acetate are poured into the reactor and a powder varnish is prepared, which is dispersed in the reactor for ~ 40 min in the presence of glue on the spherical particles of glue. To impart a certain bulk density, the powder elements are dehydrated with sodium sulfate, and the solvent is distilled off from the powder elements. The resulting powder in the reactor is washed in a washing tank, sent to wet sorting to separate the target fraction of the powder in a vacuum filter to a moisture content of 10 ... 20 wt.% And then served with graphite for drying.

As a prototype [2], the authors chose a method for producing TFP, according to which spherical powder with graphite and a moisture content of 18 ... 22 wt.% Is fed through a cyclone precipitator into a continuously operating dryer, which consists of 12 cylindrical rotating chambers with a diameter of 600 mm and a volume of 0.372 m ³ equipped with knock-out surfaces, an area of 30% of the cylindrical part of the chamber, with a continuous loading of 20 ... 40 kg of powder in terms of dry weight into each chamber, the powder is dried in boiling mode when a hot air pressure is created in each chamber of the dryer 3 00 ... 500 mm Hg due to the drying grids installed in the lower part of the chambers, each chamber of the dryer passes five temperature zones during the drying process: 1 and 2 zones - the temperature of the heated air is 93 ± 5 ° С; 3 and 4 zones - temperature of heated air 70 ± 5 ° С; 5 cooling zone - heated air temperature 50 ... 60 ° C, the total drying cycle of 1.0-2.5 hours, the capacity of the dryer 200-300 kg / h, with dry air humidity of 0.3-0.9 wt.% Dried powder unload in the receiving hopper and pneumatic transport through the cyclone precipitator is sent to dry sorting.

Currently, this design of the dryer is introduced into production upon receipt of the TFP with the provision of gunpowder with the specified characteristics, however, the design of the dryer is difficult to operate, because 12 rotating chambers are installed in the lower part of the dryer between the complex air distribution structure and between the chambers, and in the upper part, rotating chambers are installed between the exhaust hood. The installation of gaps between rotating chambers requires a high professional level, the slightest mashing with such a mass of the dryer can lead to ignition of the powder. When drying gunpowder from a specified size between the exhaust hood and the upper part of the drying chambers, as well as when unloading dry gunpowder into the hopper, the fine fraction of dry SPF is blown out. The operation of cleaning dry powder in the room is dangerous and presents certain difficulties in technological terms.

The aim of the invention is the development of a safer and more effective method of drying the TFP, providing the production of gunpowder with predetermined physico-chemical characteristics with minimal labor and energy costs.

This goal is achieved by the fact that spherical powder with a moisture content of 18 ... 22 wt.% And graphite are fed through a cyclone-precipitator to a continuously operating permanently installed dryer, in the lower part of which there is a box 500 ... 600 mm wide and 3000 ... 4000 mm long, divided into 3 sections for supplying coolant, a grid is installed on top of the box in the inside of the dryer to create air pressure under the grids 300 ... 500 mm Hg, on the sides of the box, to create tightness inside the dryer, they are installed in a vertical plane at an angle of 15 ... 20 ° of the wall from 20 ... 30% knockout surface and their height from the top of the box 1500 ... 2000 mm, drying of the powder in the first section is carried out at an air temperature of 93 ± 5 ° C; in the second section, the temperature of the heated air is 70 ± 5 ° С and 3 cooling zone is the temperature of the heated air is 50 ... 60 ° С, the powder is dried in boiling mode, while the height of the fluidized bed of powder on the grid is set to 100 ... 120 mm and adjusted by dividing grills, installed on the grid, the fluidized bed on the grid is moved due to the difference in the air supply in the duct section, the total drying cycle is 1.0 ... 2.5 hours, the dryer capacity is 200 ... 300 kg / h, with dry powder humidity 0.3 ... 0.9 wt.% dried gunpowder is discharged into the receiving hopper and by pneumatic transport through a cycle -osaditel sent for dry sorting.

The technological scheme of the dryer is shown in the drawing. In the method of drying the TFP presented by the authors, there are completely no mechanical effects between parts and nodes of the dryer. The authors in this embodiment use the temperature-time regimes of heated air supplied to the duct section by a high-pressure fan pos. 1. The air is heated to a predetermined temperature in the heaters pos.2.

Dryer pos. 3 consists of a box with a width of 500 ... 600 mm and a length of 3000 ... 4000 mm, divided into sections for supplying coolant. The upper part of the box is closed with a grid, while air pressure is created in the box under the grids 300 ... 500 mm Hg, due to which the movement of gunpowder in a fluidized bed within 100-120 mm is created due to partitions installed above the grid between the sections . The movement of gunpowder on the grid occurs due to the difference in the amount of air supplied in the dryer zone, i.e. a large amount of air is supplied to the first zone in comparison with subsequent zones. To ensure the tightness of the dryer above the box are installed in a vertical plane at an angle of 15-20 ° walls with 20 ... 30% knock-out surface, with a height of 1500 ... 2000 mm. The expandable walls provide a decrease in the air flow rate in the upper part of the dryer, which eliminates the entrainment of a fine fraction of gunpowder from the dryer. An increase in the angle of inclination of the wall of the dryer more than 20 ° does not give an effect, and a decrease of less than 15 ° contributes to the entrainment of a fine fraction of gunpowder. An increase in the walls of the dryer over 2000 mm does not affect the entrainment of the fine fraction of gunpowder, and a decrease in the height of the walls less than 1500 mm contributes to an increase in the entrainment of the fine fraction of gunpowder. burning to detonation.

The dryer operates as follows: spherical gunpowder with a moisture content of 18 ... 22% with graphite by pneumatic transport in a stream of heated air is fed into the cyclone precipitator pos. 4. During the movement of gunpowder in pneumatic transport in a stream of hot air, the removal of surface moisture and preliminary graphitization of gunpowder take place. A decrease in gunpowder humidity of less than 18 wt.% Is associated with additional labor costs, and an increase in gunpowder humidity of more than 22 wt.% Is associated with additional energy costs. From the cyclone-precipitator, the powder enters the first section, where at an air temperature of 93 ± 5 ° C, physically-chemically bound moisture is removed from the powder elements. A decrease in air temperature of less than 88 ° C leads to an extension of the drying process of gunpowder, and an increase in temperature of more than 98 ° C is associated with the danger of the process, as powder overheating is possible.

From the first section, the heated spherical gunpowder in a boiling mode flows through the installation partition into the second section, where in the stream of hot air at a temperature of 65 ... 75 ° C, the remaining physico-chemically bound moisture is removed from the powder elements to 0.3 ... 0.8 wt. % An increase in the temperature of the heated air in the second section above 75 ° C leads to overdrying of the powder, which is associated with the danger of the process, and a decrease in air temperature below 65 ° C leads to an increase in the humidity of the powder, which leads to an increase in the mass of the powder charge. From the second section, the gunpowder enters cooling at a temperature of 50 ... 60 ° C. A decrease in the temperature of chilled air below 50 ° C is associated with additional energy costs, and an increase in air temperature above 60 ° C is associated with the danger of the process.

Optimum drying of spherical powder is carried out on grids with a fluidized bed thickness of 100 ... 200 mm. Reducing the thickness of the fluidized bed of less than 100 mm leads to overdrying of the powder, and increasing the thickness of the fluidized bed of more than 120 mm leads to the production of gunpowder with high humidity. The total drying cycle of gunpowder is 1.0 ... 2.5 hours. A decrease in the drying time of less than 1.0 hours leads to an increase in the physicochemical bound moisture in the powder elements, and an increase in the drying time of more than 2.5 hours leads to the production of gunpowder with a low content moisture in the powder elements. In the process of drying the powder in a fluidized bed, the final graphitization of the powder occurs simultaneously. The productivity of the dryer is 200 ... 300 kg / h with a moisture content of gunpowder 0.3 ... 0.9 wt.%. A decrease in the productivity of the dryer less than 200 kg / h leads to the drying out of the powder, and an increase in the productivity of the dryer more than 300 kg / h leads to the production of powder with high humidity.

The dried gunpowder from the dryer continuously enters the hopper pos.5, and then through the cyclone precipitator pos.6 the dried gunpowder is sent to the dry sorting and bag. Exhausted process air after drying the gunpowder from the dryer enters the dust collector pos. 7, where impurities are separated from the process air.

Technological modes and physico-chemical characteristics of the TFP according to the method developed by the authors within the boundary conditions (example 1 ... 3) and outside the boundary conditions (examples 4 ... 5) are given in the table.

It can be seen from the table data that, according to the method developed by the authors, spherical powder supplied for drying with a moisture content of 18 ... 22 wt.% And with a graphite content in a continuous mode on a stationary dryer for 1.0 ... 2.5 hours in a fluidized bed is dried to humidity 0.3 ... 0.9 wt.%, while ensuring a productivity of 200 ... 300 kg / h.

In addition, in the drying method developed by the authors, there are no rubbing, rotating, and moving parts of the apparatus. The driving force of the process during the drying of gunpowder is pneumatic transport and the energy of hot air created by high pressure fans. During the drying process, complete blowing of gunpowder from the dryer is excluded; hazardous areas during gunpowder drying are completely eliminated. The process of drying gunpowder is fully mechanized and automated, which significantly reduced the labor and energy costs for drying the resulting spherical gunpowder.

Literature

1. Kasatkin A.G. Basic processes and apparatuses of chemical technology. - M .: Chemistry, 1973. - 750 p.

2. "Method for producing spherical powder", patent RU 2497789, C1 С06В 21/00.

Claims (1)

A method of drying spherical gunpowder, which consists in the fact that spherical gunpowder with a moisture content of 18-22 wt.% With graphite is fed through a cyclone precipitator into a continuously operating stationary dryer, in the lower part of which there is a box 500-600 mm wide and 3000-4000 mm long divided into three sections for supplying coolant, a grid is installed on top of the box in the inside of the dryer to create an air pressure under the grids of 300-500 mm Hg, on the sides of the box, to create a tightness inside the dryer, they are installed in a vertical plane under scrap 15-20 ° of the wall with a 20-30% knock-out surface and their height from the upper part of the box 1500-2000 mm, drying of the powder in the first section is carried out at an air temperature of 93 ± 5 ° C, in the second section at a temperature of heated air 70 ± 5 ° C and in the third - cooling zone - at a temperature of heated air of 50-60 ° C, the powder is dried in boiling mode, while the height of the fluidized bed of powder on the mesh is set to 100-120 mm and adjusted by separating grids mounted on the mesh, boiling the layer on the grid is moved due to the difference in the air supply in the duct section, total drying cycle 1.0-2.5 h, dryer capacity 200-300 kg / h, with moisture content of dry powder 0.3-0.9 wt.% dried powder is discharged into a receiving hopper and sent via pneumatic transport through a cyclone precipitator for dry sorting .

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