CN114130341A - Device and method for continuously synthesizing aluminum nitride powder by using conveying bed under normal pressure - Google Patents
Device and method for continuously synthesizing aluminum nitride powder by using conveying bed under normal pressure Download PDFInfo
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- CN114130341A CN114130341A CN202111425754.8A CN202111425754A CN114130341A CN 114130341 A CN114130341 A CN 114130341A CN 202111425754 A CN202111425754 A CN 202111425754A CN 114130341 A CN114130341 A CN 114130341A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/18—Stationary reactors having moving elements inside
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J4/00—Feed or outlet devices; Feed or outlet control devices
- B01J4/001—Feed or outlet devices as such, e.g. feeding tubes
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
- C01B21/072—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with aluminium
- C01B21/0722—Preparation by direct nitridation of aluminium
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2204/00—Aspects relating to feed or outlet devices; Regulating devices for feed or outlet devices
- B01J2204/002—Aspects relating to feed or outlet devices; Regulating devices for feed or outlet devices the feeding side being of particular interest
Abstract
The invention discloses a device and a method for continuously synthesizing aluminum nitride powder by a conveying bed under normal pressure, wherein the device comprises: the device comprises a storage tank, a fluidized feeding device, a vibrating device, a stirring device, a preheating device, a high-temperature nitriding conveying bed, a cooling device, a cloth bag collecting device and the like. The method comprises the processes of raw material pretreatment, fluidization and feeding and the process of aluminum powder nitridation in the high-temperature nitridation conveying bed. Through the raw material pretreatment processes of drying and screening the materials and utilizing high-purity nitrogen to carry out air replacement, the adverse effects of moisture and adsorbed oxygen contained in the materials on the nitridation reaction are reduced, and the nitridation reaction under the normal-pressure nitrogen-rich atmosphere is facilitated; the materials are subjected to nitriding reaction in a dilute phase pneumatic conveying mode in a high-temperature nitriding conveying bed, so that the contact area of the materials and nitrogen is increased, and the materials are prevented from being adhered and agglomerated; the fluidized bed technology is adopted for continuous feeding, the reaction time is short, and the obtained aluminum nitride product powder has good quality and high yield and is suitable for large-scale production.
Description
Technical Field
The invention relates to the technical field of aluminum nitride powder synthesis, in particular to a device and a method for continuously synthesizing aluminum nitride powder by a conveying bed under normal pressure.
Background
With the rapid development of electronic complete machines and electronic components towards the direction of micro size, high efficiency, high integration degree and the like, the heat generated in the unit volume of the components is increased rapidly, which puts higher requirements on the heat dissipation of substrates and packaging materials. To meet this requirement, researchers at home and abroad have developed a series of ceramic substrate materials, including aluminum nitride, aluminum oxide, beryllium oxide, and the like. Compared with other materials, aluminum nitride has the advantages of higher thermal conductivity, more stable chemical properties, more excellent mechanical strength and the like, has the most excellent comprehensive performance, and is considered as an ideal substrate and packaging material for a new generation of high-integration power component.
The most widely used method for synthesizing aluminum nitride powder at present is a direct nitriding method, and because aluminum powder continuously emits heat (Δ H ═ 318KJ/mol) in the nitriding process, although the direct nitriding method has a simple process, only a small amount of energy needs to be input at the beginning of the reaction, the subsequent reaction can be continuously carried out, and the method is suitable for industrial mass production, but also has the problems of discontinuous production, low production efficiency, easy powder adhesion, poor product quality and the like. Without improving the conventional preparation method, it is difficult to break through the high-efficiency mass production of high-performance aluminum nitride powder.
Disclosure of Invention
The invention provides a device and a method for continuously synthesizing aluminum nitride powder by a conveying bed under normal pressure, and the existing device and the existing method have the following problems of discontinuous production, low production efficiency, easy powder bonding and poor product quality.
To solve the above technical problem, an embodiment of the present invention provides the following solutions:
the embodiment of the invention provides a device for continuously synthesizing aluminum nitride powder by a conveying bed under normal pressure, which comprises a fluidization feeding device, wherein a vibration motor is arranged on the side wall of the fluidization feeding device, a stirring device is arranged in the fluidization feeding device, a material storage tank is communicated and arranged on the side wall of the fluidization feeding device, a vibration device is arranged on the side wall of the material storage tank, an air chamber is arranged at the lower part of the fluidization feeding device and is communicated with a high-purity nitrogen gas pipe, an air distribution plate is arranged above the air chamber in the fluidization feeding device, a gas flowmeter is arranged on the high-purity nitrogen gas pipe, a preheating device is communicated and arranged at the outlet of the fluidization feeding device, the preheating device is communicated with a high-temperature nitriding conveying bed, a temperature control device is arranged in the high-temperature nitriding conveying bed, and the high-temperature nitriding conveying bed is communicated and connected with a cooling device, the cooling device is connected with a cloth bag collecting device in a communicating mode, the top of the cloth bag collecting device is provided with a waste gas discharge port, and the bottom of the cloth bag collecting device is provided with a product discharge port.
Preferably, the high-temperature nitriding transport bed comprises a furnace wall on which a heating element and the temperature control device are mounted.
Preferably, the furnace wall is respectively provided with a metal shell, a heat insulation material layer and a refractory material layer from outside to inside.
Preferably, the heating element is mounted in the layer of refractory material.
Preferably, the cooling device is a dividing wall type heat exchanger, and the dividing wall type heat exchanger is respectively a metal shell, a heat insulation material layer and a refractory material layer from outside to inside.
Preferably, the cooling device is capable of rapidly cooling the high-temperature gas-solid two-phase flow to below 300 ℃.
The embodiment of the invention provides a method for continuously synthesizing aluminum nitride powder by using a normal-pressure conveying bed, which is characterized in that the method utilizes the device for continuously synthesizing the aluminum nitride powder by using the normal-pressure conveying bed, and the method comprises the following steps:
pretreating raw materials, namely pretreating aluminum powder and ammonium chloride powder according to the ratio of aluminum powder: ammonium chloride is fully and uniformly mixed according to the mass ratio of 100-50: 0-50, the mixed material is dried, the moisture in the material is removed, the material is sieved, and the particle size range of the material is 0.01-200 mu m;
the material enters a fluidization feeding device, the material after the raw material pretreatment is loaded into a storage tank, a side vibration device of the storage tank is opened at the same time, the material is fed into the fluidization feeding device through the storage tank, when a material layer reaches the height within the range of 10-1500 mm, high-purity nitrogen in a high-purity nitrogen pipe from a gas source enters a lower gas chamber after passing through a gas flowmeter, the high-purity nitrogen flows upwards through a wind distribution plate and then uniformly fluidizes agglomerated materials at the bottom in the fluidization feeding device, the agglomerated materials are crushed by a vibration motor and a stirring device, part of the materials are entrained by the nitrogen to form gas-solid two-phase flow consisting of the material and the nitrogen, and the gas-solid two-phase flow flows out of the fluidization feeding device;
and in the process of nitriding the aluminum powder in the high-temperature nitriding conveying bed, introducing the gas-solid two-phase flow into a preheating device for preheating, wherein in the preheating process, the volume of the nitrogen is expanded after the temperature of the nitrogen is raised, so that the flow velocity of the two-phase flow is rapidly increased, and the flow shape of the two-phase flow is changed into a dilute-phase pneumatic conveying state from rapid fluidization, the preheated gas-solid two-phase flow is introduced into the high-temperature nitriding conveying bed with the temperature range of 800-1600 ℃ from bottom to top, and the high-temperature nitriding reaction of the aluminum powder occurs in the high-temperature nitriding conveying bed, the temperature in the high-temperature nitriding conveying bed is monitored and adjusted in real time by a temperature control device in the high-temperature nitriding reaction process, the obtained product of the reaction is cooled by a cooling device and then collected by a cloth bag collecting device, the aluminum nitride powder product is discharged from a product discharge port of the cloth collecting device, and the waste gas is discharged from a waste gas discharge port of the cloth collecting device.
Preferably, in the raw material pretreatment process, the method further comprises the steps of performing air replacement in material gaps and adsorption oxygen removal on the surfaces of material particles on the material by using high-purity nitrogen.
Preferably, during the fluidization and feeding, the outflow speed of the gas-solid two-phase flow from the fluidization feeding device is equal to the speed of the material fed into the storage tank.
Preferably, during the nitridation of the aluminum powder in the high-temperature nitridation conveying bed and during the high-temperature nitridation reaction of the aluminum powder, the high-temperature nitridation conveying bed is kept in a micro-positive pressure state.
The scheme of the invention at least comprises the following beneficial effects:
according to the scheme, the device for continuously synthesizing the aluminum nitride powder by the conveying bed under the normal pressure carries out nitridation reaction on materials in a high-temperature nitridation conveying bed in a dilute-phase pneumatic conveying mode, so that the contact area of the materials and nitrogen is increased, the phenomenon that the materials are adhered and agglomerated mutually can be avoided, relatively more materials can be taken out by using relatively less gas, continuous feeding is realized by adopting a fluidized bed technology, the reaction time is shorter than that of the traditional direct nitridation method for preparing the aluminum nitride powder, the obtained aluminum nitride product powder has better quality and higher yield, and the device is suitable for large-scale production;
the method for continuously synthesizing the aluminum nitride powder by the conveying bed under the normal pressure reduces the adverse effects of moisture and adsorbed oxygen contained in the material on the nitridation reaction by adding the pretreatment processes of drying and screening the material and performing air replacement by using high-purity nitrogen, and is favorable for the nitridation reaction under the normal-pressure nitrogen-rich atmosphere; the materials are subjected to nitriding reaction in a dilute phase pneumatic conveying mode in the high-temperature nitriding conveying bed, so that the contact area of the materials and nitrogen is increased, and the phenomenon of adhesion and agglomeration among the materials can be avoided; the fluidized bed technology is adopted for continuous feeding, the reaction time is shorter than that of the traditional direct nitridation method for preparing the aluminum nitride powder, and the obtained aluminum nitride product powder has better quality and higher yield, and is suitable for large-scale production.
Drawings
FIG. 1 is a schematic view of an apparatus for continuously synthesizing aluminum nitride powder by a transport bed under normal pressure according to the present invention;
FIG. 2 is a schematic view of a fluidized feeder of an apparatus for continuously synthesizing an aluminum nitride powder by a transport bed under normal pressure according to the present invention;
FIG. 3 is a flow chart showing the method for continuously synthesizing aluminum nitride powder by using a normal-pressure transport bed according to the present invention.
Reference numerals:
1. a gas flow meter; 2. a vibrating device; 3. a material storage tank; 4. a fluidization feeding device; 41. an air chamber; 42. a wind distribution plate; 43. a vibration motor; 44. material preparation; 5. a stirring device; 6. a preheating device; 7. a high temperature nitriding transport bed; 8. a temperature control device; 9. a cooling device; 10. a cloth bag collecting device.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
Example one
As shown in fig. 1-2, the present embodiment provides a device for continuously synthesizing aluminum nitride powder by a normal pressure conveying bed, the device comprises a fluidization feeding device 4, a vibration motor 43 is installed on the side wall of the fluidization feeding device 4, a stirring device 5 is installed in the fluidization feeding device 4, a storage tank 3 is connected to the side wall of the fluidization feeding device 4, a vibration device is installed on the side wall of the storage tank 3, an air chamber 41 is installed at the lower part of the fluidization feeding device 4, the air chamber 41 is communicated with a high purity nitrogen gas pipe, an air distribution plate 42 is installed above the air chamber 41 in the fluidization feeding device 4, a gas flowmeter 1 is installed on the high purity nitrogen gas pipe, a preheating device 6 is connected to the outlet of the fluidization feeding device 4, the preheating device 6 is communicated with a high temperature nitriding conveying bed 7, a temperature control device 8 is installed in the high temperature nitriding conveying bed 7, the high temperature nitriding conveying bed 7 is connected with a cooling device 9, the cooling device 9 is connected with a cloth bag collecting device 10 in a communicating way, the top of the cloth bag collecting device 10 is provided with a waste gas outlet, and the bottom is provided with a product outlet.
This embodiment device, material 44 carries out the nitrogenize reaction with dilute phase pneumatic conveying's form in high temperature nitrogenize transport bed 7, not only increased the area of material 44 with nitrogen gas contact, still can avoid the phenomenon that the adhesion of material 44 each other is reunited, can use relatively less gas to take out relatively more material 44, adopt fluidized bed technique continuous feed, it is shorter than traditional direct nitrogenize legal system preparation aluminium nitride powder reaction time, the aluminium nitride product powder quality that obtains is better, output is higher, be fit for large-scale production.
Specifically, the material storage tanks 3 are distributed in pairs at both sides of the fluidized feeding device 4, have an inner diameter of 50mm to 1000mm and a height of 70mm to 2000mm, and are used for storing and supplying the pretreated material 44 to the fluidized feeding device 4.
Specifically, in order to prevent the accumulation of the material 44 in the material storage tank 3 and make it difficult to supply the material continuously, a vibration device 2 is provided on the side of each material storage tank 3 to assist the material 44 to fall continuously, and the vibration device 2 may use direct current or alternating current.
Specifically, the inner diameter of the fluidization feeding device 4 is 20 mm-2000 mm, and the height thereof is 100 mm-3000 mm.
Specifically, the preheating device 6 can be electrically heated, or heated by flue gas generated by burning fuel.
Specifically, the high-temperature nitriding transport bed 7 comprises a furnace wall on which a heating element and a temperature control device 8 are mounted. The furnace wall is respectively provided with a metal shell, a heat insulation material layer and a refractory material layer from outside to inside. The heating element is mounted in the refractory layer.
Specifically, the cooling device 9 is a dividing wall type heat exchanger, and the dividing wall type heat exchanger is respectively a metal shell, a heat insulation material layer and a refractory material layer from outside to inside.
Specifically, the cooling device 9 can rapidly cool the high-temperature gas-solid two-phase flow to below 300 ℃, and the high-temperature gas-solid two-phase flow conveniently enters the cloth bag trapping device 10 for separation and collection.
Example two
As shown in fig. 3, the present embodiment provides a method for continuously synthesizing aluminum nitride powder by using a normal pressure transport bed, which is characterized by using an apparatus for continuously synthesizing aluminum nitride powder by using a normal pressure transport bed, the method comprising:
s100, pretreating raw materials, namely mixing aluminum powder and ammonium chloride powder material 44 according to the ratio of aluminum powder: 100-50% of ammonium chloride: 0-50, drying the mixed material 44, removing water in the material 44, and screening the material 44, wherein the particle size of the material 44 is within 0.01-200 mu m;
s200, fluidizing and feeding, wherein a material 44 enters a fluidizing and feeding device 4, the material 44 subjected to raw material pretreatment is filled into a storage tank 3, a vibration device 2 on the side surface of the storage tank 3 is opened, the material 44 is fed into the fluidizing and feeding device 4 through the storage tank 3, when the height of a material 44 layer reaches the range of 10-1500 mm, high-purity nitrogen in a high-purity nitrogen pipe from a gas source enters a lower gas chamber 41 after passing through a gas flowmeter 1, the high-purity nitrogen flows upwards through a wind distribution plate 42 and uniformly fluidizes agglomerated materials at the bottom in the fluidizing and feeding device 4, the agglomerated materials are crushed by a vibration motor 43 and a stirring device 5, part of the materials are entrained by the nitrogen to form a gas-solid two-phase flow consisting of the material 44 and the nitrogen, and the gas-solid two-phase flow flows out from the side surface of the fluidizing and feeding device 4;
s300, aluminum powder nitriding in the high-temperature nitriding conveying bed, introducing the gas-solid two-phase flow into a preheating device 6 for preheating, wherein in the preheating process, the volume of the nitrogen expands after the nitrogen is heated up to cause the flow velocity of the two-phase flow to be rapidly increased, thereby changing the flow shape of the two-phase flow from rapid fluidization to a dilute phase pneumatic conveying state, introducing the preheated gas-solid two-phase flow into a high-temperature nitriding conveying bed 7 with the temperature range of 800-1600 ℃ from bottom to top, and aluminum powder high-temperature nitridation reaction is carried out in the high-temperature nitridation conveying bed 7, the temperature in the high-temperature nitridation conveying bed 7 is monitored and adjusted in real time by a temperature control device 8 in the aluminum powder high-temperature nitridation reaction process, a product obtained by the reaction is cooled by a cooling device 9, the aluminum nitride powder is collected by the cloth bag collecting device 10, the aluminum nitride powder product is discharged from a product discharge port of the cloth bag collecting device 10, and the waste gas is discharged from a waste gas discharge port of the cloth bag collecting device 10.
The method of the embodiment reduces the adverse effects of moisture and adsorbed oxygen contained in the material 44 on the nitridation reaction by adding the pretreatment processes of drying and screening the material 44 and performing air replacement by using high-purity nitrogen, and is favorable for the nitridation reaction under the normal-pressure nitrogen-rich atmosphere; the material 44 is subjected to nitriding reaction in the high-temperature nitriding conveying bed 7 in a dilute-phase pneumatic conveying mode, so that the contact area of the material 44 and nitrogen is increased, and the phenomenon of adhesion and agglomeration of the material 44 can be avoided; the fluidized bed technology is adopted for continuous feeding, the reaction time is shorter than that of the traditional direct nitridation method for preparing the aluminum nitride powder, and the obtained aluminum nitride product powder has better quality and higher yield, and is suitable for large-scale production.
In the step S100, in the raw material pretreatment process, the mixed material 44 is put into an oven for drying treatment to remove moisture in the material 44; the material 44 is screened using a screen. In the raw material pretreatment process, the method also comprises the steps of performing air replacement in gaps of the material 44 and removing oxygen adsorbed on the surfaces of particles of the material 44 on the material 44 by using high-purity nitrogen.
In the S200 step, the gas-solid two-phase flow flows out from the fluidization feeding device 4 at the same speed as the material 44 fed into the storage tank 3 during the fluidization and feeding processes, so as to realize continuous feeding. The feed rate can be adjusted within the range of 0.05kg/h to 200 kg/h. The flow rate of the high-purity nitrogen is 0.01m3/h～200m3H is used as the reference value. The gas-solid two-phase flow continuously flows out from a discharge hole on the side of the dilute phase zone at the upper part of the fluidization feeding device 4. The time for the material 44 and the nitrogen to pass through the high-temperature nitriding conveying bed 7 is 20 s-3600 s, namely the nitriding time is 20 s-3600 s.
In the step S300, the preheating temperature is 100-600 ℃. In the aluminum powder nitriding process in the high-temperature nitriding conveying bed and the aluminum powder high-temperature nitriding reaction process, the high-temperature nitriding conveying bed 7 is kept in a micro-positive pressure state. The waste gas is purified from the upper part of the trapping device and then discharged into the atmosphere.
EXAMPLE III
Pretreating raw materials, namely pretreating aluminum powder and ammonium chloride powder 44 according to the ratio of aluminum powder: 100-50% of ammonium chloride: 0-50, putting the mixture into a 400-mesh screen, putting the screen on a bracket of an oven for drying at the drying temperature of 80-120 ℃ for 2-48 h, and continuously introducing high-purity nitrogen from small holes at the bottom of the oven, wherein the high-purity nitrogen is stirred on time during the drying process to accelerate the replacement of oxygen adsorbed in gaps of the material 44. The dried material 44 is placed into a screen for screening, so as to achieve the purpose of primarily crushing the material 44 to agglomerate.
In the fluidization and feeding process, the pretreated material 44 is loosely loaded into the material storage tank 3, the vibration device 2 at the side of the material storage tank 3 is opened, part of the material is fed into the fluidization feeding device 4, when the height of a material layer reaches 10 mm-1500 mm, high-purity nitrogen from a gas source passes through the gas flowmeter 1, the gas chamber 41 at the bottom of the fluidization feeding device 4 and the air distribution plate 42, the mixed material is further crushed by the crushing action of the vibration motor 43 and the stirring device 5, part of the material fed into the fluidization feeding device 4 from the material storage tank 3 is fluidized, and is entrained by the nitrogen and continuously flows out from a discharge port at the side of a dilute phase zone at the upper part of the fluidization feeding device 4, so that uniform gas-solid two-phase flow consisting of the material 44 and the nitrogen is formed;
during the aluminum powder nitriding process in the high-temperature nitriding conveying bed, the uniform gas-solid two-phase flow is introduced into a preheater for preheating (the preheating temperature is 100-600 ℃). In the preheating process, the nitrogen is heated to expand in volume, the flow shape of the two-phase flow is changed from a fast fluidization state to a dilute phase pneumatic conveying state, the preheated two-phase flow is introduced into a high-temperature nitriding conveying bed 7 filled with high-purity nitrogen at the temperature of 800-1600 ℃ to carry out high-temperature nitriding reaction on aluminum powder, the time of the preheated two-phase flow passing through the high-temperature nitriding conveying bed 7 is 20-3600 s, and a reaction product is cooled at an outlet by a cooling device 9 and then collected by a cloth bag collecting device 10 to obtain high-performance aluminum nitride powder. In the reaction process, the high-temperature nitriding conveying bed 7 is kept at a slight positive pressure.
Example four
In the fluidization and feeding process, the sieved mixture is loosely loaded into a storage tank 3, a vibration device 2 on the side surface of the storage tank 3 is opened, part of the material is fed into a fluidization feeding device 4, when the loading height is 10 mm-1500 mm, high-purity nitrogen from a gas source enters a gas chamber 41 from the bottom of the fluidization feeding device 4 through a gas flowmeter 1, flows upwards through a wind distribution plate 42, and then under the action of a vibration motor 43, the material 44 gathered at the bottom is fluidized. The air distribution plate 42 can be composed of three layers of screens, wherein the upper layer is a 100-mesh screen with a thicker wire diameter and is used for preventing the stirring rod from scratching the middle screen; the middle layer screen is a 400-mesh screen with smaller aperture and is used for supporting the material 44; the lower layer is a 100-mesh screen with a larger silk diameter, and the lower layer is used for supporting the upper layer and the middle layer.
EXAMPLE five
Pretreating raw materials, namely putting 80g of Al powder with the average particle size of 5 mu m into a drying oven, introducing high-purity nitrogen, drying for 10 hours at the temperature of 80 ℃, stirring once every two hours during the drying process to accelerate the drying speed, removing adsorbed oxygen in gaps among Al powder particles, and then putting the dried Al powder into a 400-mesh screen for screening;
in the fluidizing and feeding process, the Al powder pretreated as above is put into a storage tank 3 and fed into a fluidizing and feeding device 4, and the fluidizing and feeding device 4 has an inner diameter of 50mm and a height of 300 mm. After the aluminum powder was fed, high-purity nitrogen gas was fed from a gas source through the bottom of the fluidization supply device 4 at a flow rate of 0.2m 3/h. After the Al powder is rapidly fluidized by the nitrogen, part of the agglomerated Al powder is crushed again under the action of the vibrating motor 43, so that the Al powder is entrained by the nitrogen and flows out of the fluidized feeding device 4 to form uniform gas-solid two-phase flow;
during the aluminum powder nitriding process in the high-temperature nitriding conveying bed, the uniform gas-solid two-phase flow enters the preheating device 6 for preheating. The preheating device 6 adopts an electric heating tube type preheater, the inner diameter of the preheater is 15mm, the length of the tube is 1.2 meters, and Al powder is preheated to 600 ℃. The preheated Al powder and nitrogen are in a uniform dilute phase pneumatic conveying state and then are introduced into a high-temperature nitriding conveying bed 7. The high-temperature nitriding conveying bed 7 is heated by adopting a resistance, the length of the bed body is 5m, the furnace temperature is 1000 ℃, and the preheated Al powder and nitrogen finish nitriding reaction in the high-temperature nitriding conveying bed 7. During the reaction process, the micro-positive pressure is always kept in the high-temperature nitriding conveying bed 7. The reaction product is cooled by a cooling device 9 at the outlet and is separated and collected in a cloth bag trapping device 10.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. The device for continuously synthesizing the aluminum nitride powder by the conveying bed under the normal pressure is characterized by comprising a fluidization feeding device, a vibration motor is installed on the side wall of the fluidization feeding device, a stirring device is arranged in the fluidization feeding device, a material storage tank is communicated and arranged on the side wall of the fluidization feeding device, a vibration device is arranged on the side wall of the material storage tank, an air chamber is arranged at the lower part of the fluidization feeding device and is communicated with a high-purity nitrogen gas pipe, an air distribution plate is arranged above the air chamber in the fluidization feeding device, a gas flowmeter is arranged on the high-purity nitrogen gas pipe, a preheating device is communicated and arranged at the outlet of the fluidization feeding device and is communicated with a high-temperature nitriding conveying bed, a temperature control device is arranged in the high-temperature nitriding conveying bed, and the high-temperature nitriding conveying bed is communicated and connected with a cooling device, the cooling device is connected with a cloth bag collecting device in a communicating mode, the top of the cloth bag collecting device is provided with a waste gas discharge port, and the bottom of the cloth bag collecting device is provided with a product discharge port.
2. The apparatus for continuously synthesizing aluminum nitride powder according to claim 1, wherein the high-temperature nitriding transport bed comprises a furnace wall on which a heating element and the temperature control device are mounted.
3. The apparatus for continuously synthesizing aluminum nitride powder according to claim 2, wherein the furnace wall comprises a metal shell, a heat insulating material layer and a refractory material layer from outside to inside.
4. The apparatus of claim 3, wherein the heating element is installed in the refractory layer.
5. The apparatus for continuously synthesizing aluminum nitride powder according to claim 1, wherein the cooling apparatus is a dividing wall type heat exchanger, and the dividing wall type heat exchanger comprises a metal shell, a thermal insulation material layer and a refractory material layer from outside to inside.
6. The apparatus for continuously synthesizing aluminum nitride powder by using a normal pressure transport bed according to claim 1, wherein the cooling means is capable of rapidly cooling the high temperature gas-solid two-phase flow to a temperature of 300 ℃ or lower.
7. A method for continuously synthesizing aluminum nitride powder by using a normal pressure transport bed according to any one of claims 1 to 6, comprising:
pretreating raw materials, namely fully and uniformly mixing aluminum powder and ammonium chloride powder materials according to the mass ratio of 100-50: 0-50, drying the mixed materials, removing water in the materials, and screening the materials, wherein the particle size range of the materials is 0.01-200 mu m;
the material enters a fluidization feeding device, the material after the raw material pretreatment is loaded into a storage tank, a side vibration device of the storage tank is opened at the same time, the material is fed into the fluidization feeding device through the storage tank, when a material layer reaches the height within the range of 10-1500 mm, high-purity nitrogen in a high-purity nitrogen pipe from a gas source enters a lower gas chamber after passing through a gas flowmeter, the high-purity nitrogen flows upwards through a wind distribution plate and then uniformly fluidizes agglomerated materials at the bottom in the fluidization feeding device, the agglomerated materials are crushed by a vibration motor and a stirring device, part of the materials are entrained by the nitrogen to form gas-solid two-phase flow consisting of the material and the nitrogen, and the gas-solid two-phase flow flows out of the fluidization feeding device;
and in the process of nitriding the aluminum powder in the high-temperature nitriding conveying bed, introducing the gas-solid two-phase flow into a preheating device for preheating, wherein in the preheating process, the volume of the nitrogen is expanded after the temperature of the nitrogen is raised, so that the flow velocity of the two-phase flow is rapidly increased, and the flow shape of the two-phase flow is changed into a dilute-phase pneumatic conveying state from rapid fluidization, the preheated gas-solid two-phase flow is introduced into the high-temperature nitriding conveying bed with the temperature range of 800-1600 ℃ from bottom to top, and the high-temperature nitriding reaction of the aluminum powder occurs in the high-temperature nitriding conveying bed, the temperature in the high-temperature nitriding conveying bed is monitored and adjusted in real time by a temperature control device in the high-temperature nitriding reaction process, the obtained product of the reaction is cooled by a cooling device and then collected by a cloth bag collecting device, the aluminum nitride powder product is discharged from a product discharge port of the cloth collecting device, and the waste gas is discharged from a waste gas discharge port of the cloth collecting device.
8. The method for continuously synthesizing aluminum nitride powder by using a normal pressure transport bed as claimed in claim 7, wherein the pretreatment of the raw material further comprises the steps of performing air replacement in the gaps of the material and removing the adsorbed oxygen on the surfaces of the material particles by using high-purity nitrogen.
9. The method of claim 7, wherein the gas-solid two-phase flow is discharged from the fluidized feeding device at a velocity equal to the velocity of the material fed into the storage tank during the fluidizing and feeding.
10. The method as claimed in claim 7, wherein the pressure inside the high-temperature nitriding conveyor bed is kept in a slightly positive pressure state during the nitriding reaction of the aluminum powder in the high-temperature nitriding conveyor bed.
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| CN114890796A (en) * | 2022-06-13 | 2022-08-12 | 洛阳翔瑞高纯材料有限公司 | Method and device for preparing aluminum nitride powder by fluidized nitridation method |
| CN115448265A (en) * | 2022-09-15 | 2022-12-09 | 大连海事大学 | Method and equipment for continuously synthesizing high-purity high-sintering-activity AlN powder in batches at high temperature |
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