RU2497789C1 - Method of producing spherical powder - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to production of spherical powders for small arms. Proposed method comprises producing powder lacquer in reactor, its dispersion to spherical particles, dehydration, ethyl acetate distillation from powder elements, washing, sorting and drying. Note here that spherical powder with graphite are fed via settling cyclone in continuous-operation drier composed of 12 cylindrical rotary chambers provided with blow-out surfaces. Loading is performed continuously while powder is dried in boiling mode at hot air head in every driver chamber of 300-500 mm Hg owing to screens mounted at chamber bottom. Every drier chamber has fine temperature zones: 1 and 2 zones - heated air temperature of 93±5°C; 3 and 4 zones - heated air temperature of 70±5°C; 5 cooling zone - heated air temperature of 50-60°C. Total drying cycle makes 1.0-2.5 h at drier efficiency of 200-300 kg/h, dry powder humidity of 0.3-0.9 wt %, dried powder is discharged in intake bin and forced by air via settling cyclone for dry sorting.

EFFECT: decreased drying cycle, higher safety owing to automation and remote control.

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 boiling flowing modes. However, the known drying methods are unacceptable for drying TFP due to the high sensitivity to temperature effects.

As a prototype [2], the authors chose a method for producing TFP, according to which a graphite suspension is introduced into the powder after squeezing from water, followed by the supply of gunpowder with graphite into a pneumatic conveying line under compressed air pressure, where during the TFP with graphite movement in a heated air stream in the mode boiling at a temperature of 80 ... 95 ° C, drying and graphitization of gunpowder takes place.

The disadvantage of this method is that during the movement of gunpowder in pneumatic transport there is a slight removal of surface moisture. In this case, the surface and internal moisture are removed during the main drying of the spherical powder in the dryer. The technological cycle of drying the TFP is ~ 2.5 ... 3.5 hours.

The aim of the invention is to reduce the drying cycle of spherical powder, ensuring safety and automation of the drying process.

This goal is achieved by the fact that spherical powder with graphite and a moisture content of 18 ... 22 wt.% Is fed through a cyclone precipitator to 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 punch surfaces of 30% from the cylindrical part of the chamber, with continuous loading into each chamber 20 ... 40 kg of gunpowder in terms of dry weight, the gunpowder is dried in boiling mode while creating a head of hot air in each chamber of the dryer 300 ... 500 mm Hg Due to the nets installed in the lower part of the dryer chambers, each dryer chamber passes five temperature zones during the drying process: 1 and 2 zones - heated air temperature - 93 ± 5 ° C; 3 and 4 zones - temperature of heated air - 70 ± 5 ° C; 5 cooling zone - heated air temperature - 50 ... 60 ° C. The total drying cycle is 1.0 ... 2.5 hours, the dryer capacity is 200 ... 300 kg / h, with a moisture content of dry powder of 0.3 ... 0.9 wt.%, The dried powder is discharged into a receiving hopper and sent through a cyclone precipitator to dry sorting.

The technological scheme of the dryer is shown in the drawing. The dryer consists of the following main units: bed pos. 1, table-base pos. 2, working chamber pos. 3, plate pos. 4, crown loading pos. 5, central axis pos. 6, heat agent distributor pos. 7, exhaust hood pos. 8, bottom cover, pos. 9. The bed serves to install the apparatus on the foundation: a worm gear is assembled inside the bed to ensure rotation of the base table.

The base table serves to ensure continuous movement of the working chambers from the place of loading to the place of unloading with the passage of the chambers through all areas of the heat agent supply.

The working chambers are used to ensure the drying of the TFP to a predetermined humidity using a hot heat agent.

The loading crown is a transitional link between the working chambers and the exhaust hood, through which the spent heat agent is transported for cleaning.

The central axis serves as the basis for the assembly of apparatus units and thrust bearings. The heat agent distributor is mounted on the dowels on the central axis, the distributor clamp is fastened with nuts and the floating base of the exhaust hood is centered.

The heat distributor consists of 6 sections. Through five sections, a heat agent with a given temperature and air are supplied to the working chambers. The heat agent is not supplied to the sixth section, since the SFP is unloaded in the corresponding chamber and a new portion of the powder to be dried is loaded.

The unloading device consists of a bottom cover and a system of levers, counterweights, rollers and a lock designed for unloading TFP from working chambers.

The plate is a metal tile with 12 holes, mounted on a table-base pos.2 and serves as a link for the transfer of heat agent between the heat agent distributor pos.7 and ducts pos.10.

An exhaust hood pos.8 is placed under the loading crown and leans through the adjustment springs on the frame provided by the installation project and serves to remove the spent heat agent.

The dryer operates as follows: the hot air supplied to the distributor has a predetermined temperature with which it enters the dryer chambers. After unloading, the wet wet TFP is again injected into each chamber. The loading of the camera is determined by the performance of the loading pneumatic transport and the speed of the base table with the cameras. All loading chambers are sequentially exposed to hot air. In this case, boiling and gushing of the TFP layer and drying takes place in each chamber. Before unloading, air enters the last chamber at a lower temperature to cool the TFP. Then the drying cycle of the powder is repeated.

Spherical powder for drying is supplied with a moisture content of 18 ... 22 wt.%. A decrease in the moisture content of the powder less than 18 wt.% Is associated with additional labor costs, and an increase in the moisture content of the TFP over 22 wt.% Is associated with difficulties in transporting the TFP in the pneumatic conveying line and an increase in the duration of the drying process of the powder.

The diameter of the dryer chambers and the volume are selected from the design features of the dryer.

An increase in the knockout surface of more than 30 wt.% On the dryer chamber leads to a weakening of the structure itself, and a decrease in the knockout surface of less than 30 wt.% Leads to the transition of the burning rate of the TFP to detonation.

The coolant is fed into the chamber of the dryer at a pressure of 300 ... 500 mm Hg. Air pressure reduction of less than 300 mmHg does not provide the boiling and flowing conditions of the TFP on the grid, and the increase in air pressure is more than 500 mm Hg leads to the removal of gunpowder from the dryer chamber.

Drying of gunpowder takes place in chambers continuously, passing 5 zones of temperature conditions. The sixth zone is the TFP discharge zone, where the coolant is not supplied to the chambers. In zones 1 and 2, the hot air temperature is 93 ± 5 ° C. A decrease in the temperature of the coolant in zones 1 and 2 of less than 88 ° C leads to an increase in the duration of the drying of the powder, and an increase in temperature of more than 98 ° C is associated with the danger of the drying process.

In zones 3 and 4, the hot air temperature is 70 ± 5 ° С. A decrease in the temperature of the coolant in zones 3 and 4 is less than 65 ° C leads to an increase in the duration of the drying process, and an increase in temperature of more than 75 ° C is associated with the danger of the process.

In the fifth zone, the TFP is cooled. Lowering the temperature of the coolant below 50 ° C leads to an increase in the duration of the drying process, and an increase in temperature above 60 ° C is associated with the danger of unloading from zone 6 into the receiving hopper.

The total drying cycle of the TFP, depending on the brand of gunpowder, is 1.0 ... 2.5 hours. A decrease in the drying time of less than 1.0 hour does not provide the desired moisture content of the TFP, and an increase in the drying time of more than 2.5 hours leads to the drying of the powder.

The productivity of the dryer is 200 ... 300 kg / h with a moisture content of TFP of 0.3 ... 0.9 wt.%.

A decrease in the productivity of the dryer less than 200 kg / h leads to the drying of the powder, and an increase in the productivity of the dryer more than 300 kg / h leads to the production of gunpowder with high humidity.

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

Technological modes and physico-chemical characteristics of spherical powder Name of indicator Example (Ex. No. 1) Etc. Number 2 Etc. Number 3 Etc. Number 4 Etc. Number 5 Diameter of the dryer chamber, mm 600 600 600 600 600 Dryer chamber volume, m 0.372 0.372 0.372 0.372 0.372 Knockout area,% thirty thirty thirty thirty thirty Humidity of the supplied air for drying, wt.% eighteen twenty 22 eighteen 25 Dryer chamber loading, kg twenty thirty 40 fifteen 45 The pressure of the coolant supplied to the drying chamber, mm Hg 300 400 500 250 600 Heat carrier temperature in 1 and 2 chambers, ° C 88 92 98 86 98 Heat carrier temperature in 3 and 4 chambers, ° C 65 70 75 63 78 Heat carrier temperature in the 5th chamber, ° C fifty 55 60 45 65 Dryer productivity, kg / h 200 250 300 150 350 The moisture content of dry powder, wt.% 0.3 0.6 0.9 0.2 1,2 Drying time, hour 1,0 1.7 2,5 0.8 3.0 Chemical resistance, mmHg 40 41 40 41 40

From the above table data it can be seen that according to the method developed by the authors, the TFP fed to the drying with a moisture content of 18 ... 22 wt.% In a continuous mode for 1.0 ... 2.5 hours is dried to a moisture content of 0.3 ... 0.9 wt.%, while providing a productivity of 200 ... 300 kg / h. In addition, the drying process is fully automated and the drying process is controlled remotely from the control panel.

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 2183604, C06B 21/00, publ. 06/20/20002, 6 s.

Claims (1)

A method of producing spherical powder, including obtaining powder varnish in a reactor, dispersing it onto spherical particles, dehydrating and distilling ethyl acetate from spherical powder, followed by washing, sorting and drying, characterized in that the spherical powder with graphite and humidity 18-22 wt.% Through cyclone precipitator is fed in continuously existing dryer 12 which is a cylindrical rotating chambers 600 mm in diameter and 0,372 m ³ volume equipped with expelling surface area of 30% of the cylindrical portion kama s, the continuous loading in each chamber 20-40 kg of powder based on the dry weight, drying the powder is carried out at the boiling pressure mode when creating a hot air dryer in each chamber 300-500 mmHg due to the nets installed in the lower part of the dryer chambers, each dryer chamber passes five temperature zones during the drying process: 1 and 2 zones - heated air temperature - 93 ± 5 ° C; 3 and 4 zones - temperature of heated air - 70 ± 5 ° C; 5 cooling zone - the temperature of the heated air is 50-60 ° C, the total drying cycle is 1.0-2.5 hours, the productivity of the dryer is 200-300 kg / h, with the moisture content of dry powder 0.3-0.9 wt.% Dried gunpowder is discharged into a receiving hopper and sent by pneumatic transport through a cyclone precipitator for dry sorting.

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