The method of obtaining ultra-fine powder and device for its implementation

 

The invention relates to the field of production of ultrafine powders of metals, their oxides, carbides, alloys, etc. In the proposed method comprising, supply and evaporation of the flow of powdered material in an inert gas under the influence in the field of centrifugal forces arc-discharge plasma, subsequent separation not evaporated portion of the material from the vapor-gas stream, cooling, condensation and separation of ultra-fine powder on the filter and re-use of inert gas according to the invention stabilize the temperature at the external borders of the field of centrifugal forces by cooling in General Autonomous, closed-loop cooling system, consisting of circuits external water cooling unit to supply gas and powder, evaporator, hardening of the node of the capacitor and the node excretion aerosol stream, refrigerator and internal flow-through water-cooled anode. The device contains a cylindrical housing of the evaporator, the anode and the cathode, the site of gas and powder collection not evaporated raw material, the hardening unit, condenser, refrigerator, filters, and a collection of ultra-fine powder, the cleaning elements, according to the invention have a shared offline, for the nodes of gas and powder, evaporator, hardening of the node of the capacitor and the node excretion aerosol stream, refrigerator and internal flow-through water cooling of the anode, the system includes a reservoir, pump, cooling tower, water ramp with instrumentation and automated power plants and the contours of the external cooling cylindrical body of the evaporator and condenser contain flowing shirts external water cooling, and the anode has a Central cavity and provided with pipes for supplying and discharging water into the inner flow water cooling circuit. Provides increased resource of continuous operation, improve the quality of the powder, ensuring the autonomy of the water quench and increase efficiency. 2 AD. and 2 C.p. f-crystals, 3 ill.

The invention relates to the field of production of ultrafine powders (UDP) metals, their oxides, carbides, alloys, etc. intended for use as an energy additives or modifiers characteristics of energetic condensed systems in the chemical industry, construction and other fields of technology.

A method of obtaining UDP metals history. true steam emanating from the arc abroad flame abruptly cooled, which leads to rapid condensation of the metal particles. This method has several disadvantages, namely, first, necessary to make the electrodes of a given composition, secondly, because of the condensation of part of the metal vapor on the walls of the evaporator and condenser requires periodic shutdown process to clean them, and replace the evaporated electrodes. Apparatus for carrying out this method does not provide powders with ascorutinum distribution of particle sizes, which is connected with the temperature inhomogeneity of the plasma in the radial plane, and with the absence of a device to remove not evaporated metal parts and large particles. Periodic stop device for cleaning and change of anode productivity. Constant contact received UDP with the atmosphere can produce powders with a metal content of not more than 90-91% (rest - oxides and nitrides of metal).

There is also known a method and a device for receiving UDP in the arc plasma [2]. This method consists in the fact that the source of powdered material in a stream of carrier gas is introduced into obrisuyu the condensation of vapors. A device for implementing this method contains the node feeding a plasma-forming gas, the site of the filing of the original powder, cooled arc discharge chamber with the actual area of the arc discharge and area volume discharge (plasma) and a quenching site. The source powder is fed into the zone of the plasma in small quantities, otherwise there will be a cooling down of the plasma that will not allow you to have the right temperature for evaporation. After passing through the plasma gas-vapor mixture enters the quenching site, where by feeding it cold cooling gas, a sudden cooling of the mixture at a rate of 105-107deg/s, leading to rapid condensation of steam from the mixture. The disadvantages of this known method and device are small resource of uninterrupted work (1-2 hours), low productivity (0.5 kg/h), a wide range of particle sizes of the obtained powder (0.005 to 50 microns) and low content in the final product of pure metal (90-92%).

The closest in technical essence and the achieved effect is a method, under which prior to exposure to the plasma powder material is also exposed to electric discharge, then separated pisarevskaya part of the material is carried out in the field of centrifugal forces, after which the Department UDP carried out on the filter, and the gas used again. The component parts of the device for UDP are the evaporator housing with upper and lower flanges installed in the evaporator, the anode and the cathode, the site of gas and powder and sequentially installed at the evaporator hardening node and the capacitor. The device is equipped with collections not evaporated raw UDP, refrigerator and filters, and in the flanges of the evaporator housing made counter at the periphery of the tangential inlet, and the cavity of the evaporator through the tangential holes on the bottom flange is connected with the cavity of the collection not evaporated raw material, a capacitor connected serially fitted with a fridge, filter and collection UDP, and the free cavity collections not evaporated raw material and UDP are connected through the cleaning elements with a node in the gas and powder through the tangential holes on the bottom flange and holes quenching site. Site of gas and powder, hardening node, a capacitor and a refrigerator equipped with flow-through cooling system from the municipal water supply [3].

Disadvantages adopted for the nearest equivalent method and device for receiving UDP are the high content in krichevskoy arc, heating of the evaporator to a temperature above 373 K due to the lack of effective cooling, the violation of the cycle of continuous operation of the device due to periodic reduction of water consumption in the system of non-Autonomous water supply to a level below the minimum required for cooling elements of the device within the specified temperature limits.

The technical result is to increase the resource of continuous operation, improving the quality of the UDP, to ensure that water cooling device and increase efficiency.

The technical result is ensured by the fact that in a method of producing ultrafine powder comprising flow and evaporation of the flow of powdered material in an inert gas under the influence in the field of centrifugal forces arc-discharge plasma, subsequent separation not evaporated portion of the material from the vapor-gas stream, cooling, condensation and separation of ultra-fine powder on the filter and re-use of inert gas according to the invention stabilize the temperature at the external borders of the field of centrifugal forces by cooling in General Autonomous, closed-loop cooling system, consisting of circuits external water cooling unit to supply the a and the internal flow water cooling of the anode.

The proposed apparatus for producing ultrafine powder containing a cylindrical evaporator housing with upper and lower flanges, made them a counter on the periphery tangential holes, the anode and cathode installed in the evaporator, the site of gas and powder collection not evaporated raw material, the cavity of which is connected with the cavity of the evaporator through the tangential holes on the bottom flange, and sequentially installed at the evaporator hardening node, condenser, refrigerator, filters, and a collection of ultra-fine powder, as well as the cleaning elements for communication through the tangential holes on the bottom flange and holes quenching site free of cavities collections not evaporated raw material and ultra-fine powder with a node in the gas and powder according to the invention it is provided with a General Autonomous, closed, stable over temperature cooling system in the form of contours of external cooling units, gas and powder, evaporator, hardening of the node of the capacitor and the node excretion aerosol stream, refrigerator and internal flow-through water cooling of the anode, the system includes a reservoir, pump, cooling tower, water ramp to the market external cooling cylindrical body of the evaporator and condenser contain flowing shirts external water cooling, and the anode has a Central cavity and provided with pipes for supplying and discharging water into the inner flow water cooling loop.

The costs of cooling water at the site of gas and powder, anode, evaporator, condenser and node removal aerosol stream support in relation 1/1/5/5/10 respectively. The anode is supplied with quick-release removable radiator with a tungsten rod. A comparative analysis of the essential features of the closest analogue and the proposed method shows that distinguishing the essential features of the proposal are such, in accordance with which:

- conducted intensive water cooling with separate water circuits integral parts of the entire flow path of the processed material from powdered material in an electric arc discharge to the UDP output from the refrigerator;

- cool the working part of the anode node notcause running water;

- put in the replacement radiator at the end of the working part of the anode site easily removable tungsten rod.

Thus, the proposal meets the patentability criteria of “novelty.”

Not known to the authors similar essential features that are required to resolve this for those who will be more readily understandable from a consideration of the figures of the drawing, where:

Fig.1 is a General diagram of a device for implementing the method of receiving UDP;

Fig.2 is a schematic diagram of a water cooling high-temperature sites of the plasma torch (6) for example, node evaporator (2) with the node gasolinewall stabilization and a removable water-cooled anode;

Fig.3 - diagram of the water-cooled anode with removable radiator and easily removable tungsten rod.

In Fig.1 presents a schematic diagram of the proposed device, which contains the site of gas and powder to 1 arc evaporator 2, the hardening node 3, the condenser 4, the node excretion aerosol powder 5 from the condenser 4, the plasma torch 6, the node gasolinewall stabilization 7 arc discharge and plasma flow, performing the functions of the unit to supply plasma gas.

Also in the composition of a water-cooled plasma torch 6 is the node removal not evaporated raw material 8 from the evaporator 2 is connected by a pipeline with a collection not evaporated raw material 9, and the refrigerator 10 (for example, coil type with water cooled jacket), coupled with catcher in the form of a system of series-connected filters, including the filter 11 with a collection UDP 12 and sanitary filters 13. Vovania flow of process gases 15 and valves 161-163and rotameters 171-173respectively. The collection is not evaporated raw material 9 through the valve 164and rotameter 174connected to the filters 13. The valve 161-163and rotameters 171-173supply of process gases respectively to the dispenser 18 is connected by a pipeline with a node in the feed gas and the powder 1, on site gasolinewall stabilization 7 and hardening node 3 condenser 4.

The cooling water unit for UDP is designed to remove heat from high-temperature sites torch(1, 2, 3, 4, 5, 10) with the aim of increasing productivity and the product quality and process safety.

Part of the cooling water enter the tank 19, the pump 26, a water ramp 23, cooling tower 27, the cooling water infeed of gas and powder to 1, the cooling water evaporator 2, the cooling water of the condenser 4 and node removal aerosol stream 5, the cooling water of the refrigerator 10, rotameters 221-225valves 211-218piping, valves 211-218elements controlling the flow of water 221-225geometric characteristics to the RA water, as refrigerant, not approaching the critical point less than 30°C. the Critical point for water in this case is the temperature of its boiling point.

The device receiving UDP works as follows. Before turning on the compressor 14 and the internal volume of the device receiving UDP vacuum to a residual pressure of 0.03-0.07 kg/cm2fill with an inert gas such as argon to atmospheric pressure, again vacuum to a residual pressure of not more than 0.03 kg/cm2and fill through the gas manifold 15 process gas, such as argon, argon with helium or other gases to a pressure of about 4 kg/cm2. Then include the water pump 26. The water pump through the valve 216delivers water from the tank 19 to a water ramp 23, then through the gates 211-215and rotameters 221-225water is supplied to the high temperature contours nodes torch 1, 2, 3, 4, 5, 10 and cools them, after which it enters the cooling tower 27, where her intense cooling. With the tower 27 chilled water enters the tank 19 where again is delivered by a pump 26 to the contours of the high-temperature sites torch 1, 2, 3, 4, 5, 10. Thus, the cooling system is a closed loop that logicheskogo process and its continuity. The total time of entering the mode water cooling circuit depends almost from the time the operator to regulate the flow of water through all of the high-temperature sites of the plasma torch and the time of exposure operation of the circuit is necessary in order to ensure stable and uninterrupted operation of the cooling circuit. After the water cooling system on the regime includes a compressor 14, which supplies process gas through the distribution unit and controlling the flow of process gases 15 (hereinafter gas ramp 15), the valve 162and rotameter 17 with a flow rate of 10-15 m3/h to node 7 through the gas manifold 15, the valve 163and rotameter 173with a flow rate of 10-15 m3/h in hardening node 3 and through the gas manifold 15, the valve 161and rotameter 171in the dispenser 18 with a flow rate of 1-2 m3/hours of dispenser 18 in a mixture with the powdered raw material process gas serves in the areas of electric arc discharge and plasma evaporator 2. The flow rate of the supplied gas is regulated by the valves 161-163and controlled by rotameters 171-173. The original powder particles under the influence of high temperature in the zone of the electric arc and plasma into the vapor state.

Pipari robinah strength of the vortex, stabilizing the plasma, via the node removal 8. Not evaporated particles through the holes and the gas pipeline in the aerosol flow is directed into the collection not evaporated raw material 9, which uses the filter, for example, filtration fabric particle capture, and process gas in the gas mains are served in the filters 13, where it is mixed with the main stream. Trapping in the plasma torch of coarse particles (>100 µm) is provided due to their separation from the gas-vapor flow under the action of centrifugal and gravitational forces and travel through a water-cooled channel 20. The formation of the vortex in the evaporator 2 provide a supply of process gas into the site gasolinewall stabilization 7 arc discharge and plasma flow in which the gas is fed through holes in the flange tangentially relative to the cylinder of the evaporator 2, under its cover. Electric arc with adjustable current-voltage characteristics create between two tungsten electrodes, one of which (the cathode) is mounted on top of the evaporator 7, and the other (water-cooled anode 25) on the cylindrical part of the evaporator. The arc is stabilized, i.e., stably held in the zone of the axis of the evaporator with gas the capacity level invest in gas power not exceeding 35 kWh/kg raw material), which is required for heating and evaporation of 1 kg of particles of the initial powder and the passing from the chamber of the evaporator 2 gas. In addition, gasolinewall stabilization of the plasma in the center of the evaporator protect its walls from overgrowing condensed from the vapor-gas flow material, and protection from exposure to high temperatures, which reduces heat loss and increases the evaporation rate of the raw materials to more than 80%. Using a water-cooled anode provides heat removal from wolframio rod and virtually eliminates erosion of the working surface of the anode rod. Together, this enables us to arrange a continuous process of evaporation of the source powder in the plasma, to prevent impurity metals in the main product and extend the life of its continuous operation up to 90-100 including High performance and relatively low levels of deposited power per unit production is also due to the fact that evaporation of the source materials used not only plasma with temperature 5000-7000 K, but the electrical discharge temperature 10000-12000 K.

Steam and gas flow from the plasma zone of the evaporator 2 is served in the condenser 4, where the passage through the nozzle and races the rez hardening node 3. There is condensation of vapors of the material at a speed of not less than 106K/C. the Formed aerosol stream from the process gas and aerosol particles with a temperature of 100-150°C through node removal 5 of the capacitor 4 is served in the refrigerator 10. Then cooled to room temperature, the aerosol flow is directed to the filter 11. It is the capture UDP, for example, using Mylar fabric and then accumulate in the collector 12, which is tightly connected to the filter 11. Process gas after the filter 11 additionally cleaned for sanitary filters 13 and after compression with a compressor 14, for example, membrane-type is sent to the receiver 15. A collection of 12 periodically released from the accumulated target product - UDP, for which the collection otstegivayut from working filter 11 without disturbing the tightness of the installation. Surgery is performed in a sealed box filled with an inert gas. After sealing the collection is removed from the box. Thus, the technological cycle of the device is closed, which ensures its ecological purity, explosion and fire safety.

In Fig.2 is a schematic diagram of a water cooling evaporator and its anode with jet cooling. Django cooling 4, jacket water cooling 5, the output fitting water cooling 6 and fitting water cooled anode 7. The process gas enters through the holes of the site gasolinewall stabilization 2 tangentially relative to the cylinder of the evaporator in its internal volume and provides stabilization of the plasma along the axis of the evaporator. Not evaporated raw material due to centrifugal forces derived from the vapor zone to the periphery of the evaporator and through the site excretion of 3, representing an annular groove on the inner side of the lower part of the evaporator in the flange, with holes tangentially arranged relative to the cylinder of the evaporator towards the flow of process gases, i.e., to meet tangentially made holes in the flange of the evaporator associated with the cover through the openings and the gas line enters the collection not evaporated raw material. Water through a water ramp device through a pipeline that goes through the inlet fitting water cooling 4 in the jacket water cooling 5 evaporator and then through the output fitting water cooling 6 is fed to the cooling tower. Water-cooled anode is installed on the evaporator through the nozzle 7 so that the conical portion of the tungsten rod was in C is cooled and removable tungsten rod, which contains a tube of the cooling water inlet 1, the inner cavity 2, the case of the anode 3, a tungsten rod 4, a removable heat sink 5 and the output fitting 6. The design of the anode for water cooling its body and a tungsten rod with the aim of increasing the resource of continuous operation of the device and avoid falling into UDP impurity metals (copper, tungsten). Water through a water ramp enters the tube 1, defines an internal cavity 2, the cooling copper anode body 3, a removable heat sink 5 and the tungsten rod 4, and out through the fitting 6 on the tower.

Example 1. In the device load aluminum powder with particle size50 μm, a specific surface area of 0.3 m2/g and a content of active aluminum 99,2%. 4-5 with the output from the unit with Autonomous vodopoglaschenie and water-cooled anode to produce a powder of spherical aluminum form with a specific surface area of about 10 m2/g, a particle size in the range of 0.05-0.5 μm and the content of active aluminum more than 98.5 per cent. Resource of continuous operation of the device is 100 hours.

Example 2. In the device loads the aluminum powder with the same characteristics when turned off the water cooling of the anode. 4-5 with the output of the plant to get ultrasnap metals (copper, Wolfram) 0.1 wt.% without changing other characteristics.

Example 3. In the device loads the aluminum powder with the same characteristics (example 1) when disabled water cooling evaporator. 4-5 with the output of the plant to get ultra-fine aluminum powder with characteristics similar to those shown in example 1, after 10 minutes there is a heating of the evaporator housing to a temperature of 323...333 K, and through 30 mines up to 373...383 K with automatic power failure device.

Sources of information

1. ) I. D. and other Ultra-fine system. M: Atomizdat. 1977, S. 30-32.

2. French patent No. 2071176, IPC H 05 H 1/00, 1971.

3. EN 2068400, C1, 1996.

Claims

1. The method of obtaining ultrafine powder comprising flow and evaporation of the flow of powdered material in an inert gas under the influence in the field of centrifugal forces arc-discharge plasma, subsequent separation not evaporated portion of the material from the vapor-gas stream, cooling, condensation and separation of ultra-fine powder on the filter and reuse of inert gas, characterized in that stabilize the temperature at the external borders of the field of centrifugal forces by cooling in General the gas and powder, evaporator, hardening of the node of the capacitor and the node excretion aerosol stream, refrigerator and internal flow-through water-cooled anode.

2. The method according to p. 1, characterized in that the costs of cooling water at the site of gas and powder, anode, evaporator, condenser and node removal aerosol stream support in the ratio of 1:1:5:5:10, respectively.

3. Apparatus for producing ultrafine powder containing a cylindrical evaporator housing with upper and lower flanges, made them a counter on the periphery tangential holes, the anode and cathode installed in the evaporator, the site of gas and powder collection not evaporated raw material, the cavity of which is connected with the cavity of the evaporator through the tangential holes on the bottom flange, and sequentially installed at the evaporator hardening node, condenser, refrigerator, filters, and a collection of ultra-fine powder, as well as the cleaning elements for communication through the tangential holes on the bottom flange and holes quenching site free of cavities collections not evaporated raw material and ultra-fine powder with a node in the gas and powder, characterized in that it is provided with a General Autonomous, closed, stabilizer the powder, evaporator, hardening of the node of the capacitor and the node excretion aerosol stream, refrigerator and internal flow-through water cooling of the anode, the system includes a reservoir, pump, cooling tower, water ramp with instrumentation and automated power plants and the contours of the external cooling cylindrical body of the evaporator and condenser contain flowing shirts external water cooling, and the anode has a Central cavity and provided with pipes for supplying and discharging water into the inner flow water cooling loop.

4. The device according to p. 3, characterized in that the anode is supplied with quick-release removable radiator with a tungsten rod.

 

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