CN215103688U - Single-layer multi-furnace melting system - Google Patents

Abstract

The utility model discloses a single-layer multi-furnace melting system, which comprises at least two-stage fluidized melting furnaces, wherein each melting furnace comprises a furnace body, a heating core, an air distribution plate and a guide cylinder, the lower part in the vertically arranged cylindrical furnace body is provided with the air distribution plate, and the air distribution plate is fully distributed with air caps or air holes; a heating core is arranged on the upper surface close to the air distribution plate, a plurality of guide cylinders are arranged above the heating core, and through holes are fully distributed on the cylinder wall of each guide cylinder; the top surface and the bottom surface of the furnace body are respectively provided with an argon outlet and an argon inlet; the upper part and the lower part of the furnace body are respectively provided with a material inlet and a material outlet; the material outlet of the melting furnace of the previous stage is connected with the material inlet of the melting furnace of the next stage through a material conveying pipeline. The system of the utility model can realize the continuity of the production process of the silicon carbide and ensure the stability of the product; the reaction time can be shortened from about 15-25 hours to 1-2 hours at present, and the production efficiency is greatly improved.

Description

Single-layer multi-furnace melting system

Technical Field

The utility model relates to a melting device of production carborundum especially relates to a many stoves of individual layer melting system of production carborundum, belongs to the equipment field of production carborundum.

Background

The silicon carbide material has wide application, and is mainly applied to the solar photovoltaic industry, the semiconductor industry and the piezoelectric crystal industry. At present, the preparation of the conventional silicon carbide mainly comes from artificial synthesis, and the preparation method mainly comprises a sublimation method and a melting method. Wherein, the sublimation method is that the silicon carbide furnace burden in a carbon tube furnace with vacuum of 10-30 mm Hg is sublimated on the inner wall to grow and synthesize silicon carbide; the melting method is to embed a sealed graphite dry crucible in an electric furnace with the temperature strictly controlled at 2600 ℃, and place the bonded and formed silicon carbide ingredients in the sealed graphite dry crucible in advance for melting to produce the silicon carbide. However, the above method has the following disadvantages in the production process: (1) the melting method and the sublimation method both belong to intermittent production, and products are discharged from a furnace and manually classified and sorted; (2) the melting method has incomplete reaction of materials, the materials in the furnace only form a silicon carbide product at the central part after the preparation is finished, and other materials have incomplete reaction, such as an insulating layer, an oxygen silicon carbide layer, an adhesive layer and an amorphous substance layer; the sublimation method has the disadvantages that the growth rate of silicon carbide crystals is low, and the temperature management in the reaction space is difficult; (3) in the process of preparing the silicon carbide by the melting method and the sublimation method, the mass transfer efficiency and the heat transfer efficiency are low because the raw materials are bonded together. However, the fluidization method can effectively improve the uniform mixing degree of the raw materials for preparing the silicon carbide, improve the mass transfer and heat transfer efficiency, avoid the defects of slow generation rate and difficult control of the operation temperature of the sublimation-process silicon carbide crystal, and simultaneously overcome the defect that the conventional melting-process resistance furnace forms different furnace material layers from inside to outside to cause the recycling of the secondary smelting furnace of the unreacted and complete raw materials. Conventional silicon carbide production methods are largely classified into a melting method and a sublimation method.

The melting method has the characteristics that: the main equipment for preparing silicon carbide by the melting method is a resistance furnace. Wherein, the two ends of the resistance furnace are end walls, a graphite electrode is arranged near the center, and the furnace core body is connected between the two electrodes; the furnace core is filled with reacting furnace materials (mainly quartz and carbon raw materials) and the outer part is a heat insulating material. When the furnace burden is melted to produce silicon carbide, the temperature of the furnace core body is generally ensured to rise to 2600-2700 ℃ by supplying power. At the moment, the electrically heated furnace core can transfer heat to the furnace charge, so that silicon carbide can be generated and carbon monoxide can be released when the furnace charge is gradually heated to reach 1450 ℃ or above. Along with the prolonging of the heating time, the high-temperature range of the furnace charge is continuously expanded, and simultaneously, more and more silicon carbide is generated, so that the silicon carbide is finally promoted to evaporate, move and crystallize in the furnace to form a cylindrical crystallization cylinder. When the temperature in the crystallization cylinder exceeds 2600 ℃, part of the silicon carbide products begin to decompose again, and the decomposed silicon is combined with carbon in the furnace burden to form new silicon carbide.

The common melting method silicon carbide production equipment mainly comprises a raw material mixing device, a melting production device (a resistance furnace) and a product treatment device. The silicon raw material, the carbonaceous raw material and the auxiliary material which are crushed into certain particle sizes are mixed uniformly in a mixing device and then are sent into a melting production device; the mixture and the recycled waste material generated in the previous operation are subjected to high temperature of about 2600 ℃ in a melting production unit to produce a high-purity silicon carbide product. In a fusion production unit, however, not all of the feedstock and recycled spent material is converted to silicon carbide product in the electric resistance furnace. Therefore, in the subsequent product treatment unit, the recycled waste material which does not generate qualified products enters the melting production unit again after being treated to continuously produce the silicon carbide. Meanwhile, the heat of the high-temperature silicon carbide generated in the melting production process in the process is not recycled.

The sublimation method has the characteristics that: the sublimation method is the most common method for commercially producing silicon carbide crystals at present, and is characterized in that pretreated silicon carbide powder is placed between a graphite crucible and a porous graphite tube, and silicon carbide generated under the conditions of inert atmosphere (usually argon) and 2500 ℃ is subjected to sublimation growth preparation, but the method has slow silicon carbide generation rate in the production process and is not easy to control the crystal form size of the grown silicon carbide crystals; meanwhile, the operation temperature is not easy to control in the production.

The prior art has the following defects:

(1) the melting method and the sublimation method both belong to intermittent production, and products are discharged from a furnace and manually classified and sorted;

(2) the melting method has incomplete reaction of materials, the materials in the furnace only form a silicon carbide product at the central part after the preparation is finished, and other materials have incomplete reaction, such as an insulating layer, an oxygen silicon carbide layer, an adhesive layer and an amorphous substance layer; the sublimation method has the disadvantages that the growth rate of silicon carbide crystals is low, and the temperature management in the reaction space is difficult;

(3) in the process of preparing the silicon carbide by the melting method and the sublimation method, the mass transfer efficiency and the heat transfer efficiency are low because the raw materials are bonded together.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a many stoves of individual layer melting system to solve the inhomogeneous problem of traditional carborundum production process mass transfer heat transfer, realize the serialization production process and each stage temperature of carborundum and control, overcome traditional carborundum production process material conversion efficiency once through, the drawback of product exhaust material continuation separation retrieval and utilization.

In order to achieve the above object, the present invention adopts the following technical solutions:

a single-layer multi-furnace melting system comprises at least two-stage fluidized melting furnaces, wherein each melting furnace comprises a furnace body, a heating core, an air distribution plate and a guide cylinder, the air distribution plate is arranged at the lower part in a vertically arranged cylindrical furnace body, and air caps or air holes are distributed on the air distribution plate; a heating core is arranged on the upper side close to the air distribution plate, and a plurality of guide cylinders which are arranged at intervals and are vertical in the axial direction are arranged above the heating core; the upper part and the lower part of the furnace body are respectively provided with a material inlet and a material outlet, and the material outlet of the upper-level melting furnace is connected with the material inlet of the lower-level melting furnace through a material conveying pipeline.

The utility model discloses a preferred embodiment is equipped with argon gas export and argon gas entry respectively in the top surface and the bottom surface of this furnace body.

The utility model discloses an optimal embodiment the through-hole is covered with on the section of thick bamboo wall of draft tube, and the through-hole aperture is 3 ~ 6 millimeters.

The utility model discloses a preferred embodiment, the aerofoil on hood or the wind hole be circular or regular hexagon, the hood diameter is 30 ~ 80 millimeters, the wind hole diameter is 3 ~ 8 millimeters.

The utility model discloses an optimized embodiment, the centre-to-centre spacing is 1.0 ~ 1.5 times of hood or wind hole diameter between hood or the wind hole.

According to a preferred embodiment of the utility model, the guide cylinders are fixed at a position 0.05-0.10 m above the air distribution plate through fixing parts, and the distance between the guide cylinders is 3-5 times of the diameter of the guide cylinders; the height of the guide shell (4) is preferably 0.2-0.6 m, the diameter range of each guide shell (4) is preferably 0.1-0.3 m, and the guide shell (4) is generally cylindrical.

In a preferred embodiment of the present invention, the shape and size of the air distribution plate are the same as the cross section of the furnace body.

In a preferred embodiment of the utility model, the cross section of the furnace body is circular, and the inner diameter is 1.0-8.0 m; the heating cores are uniformly arranged along the circular periphery at an alpha angle of 10-90 degrees; the heating core is arranged above the air distribution plate (3) by 0.03-0.2 m.

In a preferred embodiment of the utility model, the cross section of the furnace body is square, and the side length is 1.0-2.8 m; the heating core is parallel to one side of the square and is uniformly arranged along the vertical side; each heating core is arranged between the rows of the air caps or the air holes and is arranged above the air distribution plate by 0.03-0.2 m, and the distance between the heating cores is 2 times of the diameter of the air caps or the air holes.

The utility model discloses use fluidization technique to provide a novel carborundum production device as the basis, can realize carborundum preparation process segmentation reaction and segmentation control, not only can realize the continuity of carborundum production process, but also can improve carborundum crystal conversion rate.

The utility model discloses compare with common melting method and sublimation, produced amorphous, pure beta-SiC looks, pure alpha-SiC looks, alpha/beta-SiC mixed phase product can carry out corresponding temperature control in fluidized bed melting furnace as required, and need not separate out the exhaust material as raw materials return resistance furnace and continue melting production carborundum like conventional melting method, can realize the production process serialization completely and guarantee carborundum product stability. The reaction time for producing the qualified silicon carbide product can be shortened from about 15-25 hours in the past to 1-2 hours at present, so that the production efficiency is greatly improved; the residual heat of the fluidized gas is fully applied to drying the production raw materials in the production process of the silicon carbide, so that the effective recycling of energy is realized, and the energy consumption and the production cost are reduced.

Drawings

FIG. 1 is a schematic view of the structure of the present invention (an embodiment of a three-stage melting furnace);

FIG. 2 is a schematic view of a (cylindrical) melting furnace according to the present invention;

FIG. 3 is a schematic cross-sectional view (draft tube distribution) in the middle of FIG. 2;

FIG. 4 is a cross-sectional (heater core distribution) schematic view of the lower portion of FIG. 2;

FIG. 5 is a schematic view of a (square barrel) melting furnace according to the present invention;

FIG. 6 is a cross-sectional view (draft tube distribution) in the middle of FIG. 5;

figure 7 is a cross-sectional (heater core distribution) schematic view of the lower portion of figure 5.

Description of reference numerals: 1. furnace body, 2, heating core, 3, air distribution plate, 4, draft tube, 5, material entry, 6, material export, 7, argon gas entry, 8, argon gas export, 9, argon gas output pipeline, 10, argon gas input pipeline, 11, material surface, A, first order melting furnace, B, second level melting furnace, C, third level melting furnace.

Detailed Description

The invention will be described with reference to specific embodiments and drawings, the advantages and features of which will become more apparent as the description proceeds. It is to be understood that these examples are illustrative only and are not to be construed as limiting the scope of the invention in any way. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention, and it is intended that all such changes and modifications fall within the scope of the invention.

Referring to fig. 1-7, an embodiment of a single-layer multi-furnace melting system of the present invention includes three (and possibly more than two) fluidized melting furnaces, namely: the smelting furnace comprises a first-stage smelting furnace A, a second-stage smelting furnace B and a third-stage smelting furnace C, wherein a material outlet 6 of the first-stage smelting furnace A is connected with a material inlet 5 of the second-stage smelting furnace B through a material conveying pipeline, and a material outlet 6 of the second-stage smelting furnace B is connected with a material inlet 5 of the third-stage smelting furnace C through a material conveying pipeline (see figure 1).

The structure of each melting furnace is shown in fig. 2-7, and comprises a furnace body 1, a heating core 2, an air distribution plate 3 and a guide cylinder 4, wherein the air distribution plate 3 is arranged at the lower part in the vertically arranged cylindrical furnace body 1, and an air cap or an air hole is fully distributed on the air distribution plate 3; a heating core 2 is arranged on the upper side close to the air distribution plate 3, a plurality of guide cylinders 4 which are arranged at intervals and are vertical in the axial direction are arranged above the heating core 2, and through holes are fully distributed on the cylinder walls of the guide cylinders 4; the top surface and the bottom surface of the furnace body 1 are respectively provided with an argon outlet 8 and an argon inlet 7; the upper part and the lower part of the furnace body 1 are respectively provided with a material inlet 5 and a material outlet 6. The draft tube 4 is generally cylindrical.

The working principle and the concrete structure of the present invention are further explained with the attached drawings as follows:

the utility model discloses hierarchical melting furnace of multistage series connection adopts the hierarchical melting mode of many furnaces series connection (as shown in fig. 1), and its principle is exactly to fall into the raw materials and goes on in tertiary melting furnace A, B, C (this embodiment), adopts fluidized bed melting to realize that the carborundum raw materials is even in the stove mass transfer heat transfer, has solved the phenomenon that traditional preparation method exists many product layers fundamentally, has improved the unicity and the conversion rate of product. The melting furnace of each grade is all controlled the in-road temperature by graphite electrical heating core 2, is provided with air distributor 3 in the stove, is covered with hood or wind hole on the air distributor 3, and hood or wind hole can adopt circular structure or regular hexagon structure, and the hood diameter is generally at 30 ~ 80 millimeters, and the wind hole diameter is at 3 ~ 8 millimeters, and concrete size is decided according to air distributor size. The central distance between the blast caps or the blast holes is 1.0-1.5 times of the diameter of the blast caps or the blast holes. The wind cap or the wind hole on the wind distribution plate 3 also ensures that the wind speed of the small hole of the inert gas wind cap and the wind hole is controlled to be 25-55 m/s under the state of producing silicon carbide, and ensures that the materials in each layer of bed layer in the furnace are in a fluidized state. The height of each melting furnace bed surface 11 can be controlled within 0.3-1.0 m, and the gas flow velocity of the bed surface is controlled within 0.8-1.5 m/s. The utility model discloses a guide shell 4 is all set up in every melting furnace, and the arrangement of guide shell 4 is as shown in figure 2, figure 3, figure 5 and figure 6. A plurality of guide cylinders 4 can be arranged in each melting furnace, and the height h2 of each guide cylinder 4 is 0.2-0.6 m according to the height of each melting furnace hearth layer. The guide cylinder 4 is fixed above the air distribution plate 3 through a fixing piece, and the distance h1 between the guide cylinder and the air distribution plate 3 is 0.05-0.10 m; the distance s and n between the adjacent guide cylinders 4 is 3-5 times of the diameter of the guide cylinders, and the diameter range of each guide cylinder 4 is 0.1-0.3 m; a plurality of small holes can be formed around the periphery on each guide cylinder 4, the aperture of each small hole is 3-6 mm, and a plurality of layers of small holes can be arranged on the guide cylinders 4. In a fluidized melting bed in each melting furnace, after materials in the bed are fluidized in a molten state through an upper wind cap or a wind hole of a wind distribution plate 3, the materials further form internal circulation of the materials from bottom to top through the inside of a guide cylinder 4 (the materials form bubbles in the bed materials of the melting bed through Ar gas coming from the wind distribution plate to drive the materials to enter the inside of the guide cylinder and then flow out of the guide cylinder 4 and then circulate into the guide cylinder 4 through small holes on the guide cylinder 4 and the lower part of the guide cylinder 4 in cycles, the guide cylinder 4 has the function of promoting further mixing reaction of the bed materials to ensure uniform reaction temperature, and the small holes on the guide cylinder 4 are used as channels for promoting circulation of the materials in the melting bed), so that uniform temperature and sufficient mass transfer of the reaction materials in the furnace are further ensured, and the sufficient conversion of the materials is realized. The utility model discloses a when carrying out carborundum product production in the hierarchical melting stove of many stoves series connection, mainly control carborundum product type according to operating temperature. In the process flow, the production raw materials after drying and crushing firstly enter the utility model discloses an in first-stage melting furnace A, gradually get into in subsequent multistage melting furnace (second level melting furnace B, third level melting furnace C) after certain dwell time. The material is from last one-level melting furnace entering next one-level melting furnace's passageway all adopts material conveying pipeline, and material conveying pipeline adopts the high temperature resistant stainless steel material of amorphous refractory lining. The residence time of the melting furnace at each stage can be different, and the residence time can be estimated approximately by the quotient of the volume of the reaction bed material in the furnace and the product volume flow rate per unit time. Finally producing qualified silicon carbide products. Similarly, when the temperature in the multi-stage fluidized melting furnace is controlled at 2000 ℃, the reaction time is controlled by controlling the number (stages) of the melting furnaces connected in series, and the production of the beta-SiC crystal product with the raw materials completely converted is realized. When the temperature in the multi-stage melting furnace is controlled to be higher than 2000 ℃, the alpha-SiC crystal product can be finally generated. In the above process for producing silicon carbide, the raw materials to be produced in each melting furnace are in a molten state, and the raw materials are in a liquid boiling state under the fluidization action of an inert gas (generally, Ar gas).

The single furnace bed surface (namely the cross section shape of the furnace body 1) of each level of melting furnace of the utility model can adopt a round shape (as shown in figures 2-4) or a regular quadrangle shape (as shown in figures 5-7), and the bed diameter D of the single furnace of the round bed surface is 1.0-8.0 meters; and for a square bed surface, the length L and the width W of each fluidized bed layer are both 1.0-2.8 m. A layer of heating core 2 is arranged on the air distribution plate 3 of the single melting furnace. The heating core 2 is installed in a manner related to the shape of the bed of the single fluidized melting furnace. When the bed surface is circular, the heating cores can be uniformly arranged along the circular periphery at an angle alpha, and the angle alpha can be between 10 and 90 degrees (as shown in figure 4). When the bed surface is a regular polygon, the heating cores are uniformly arranged along one side of the square as shown in fig. 7. The heating cores 2 of the furnaces with the two bed surfaces are arranged between rows of the wind caps or the wind holes and are arranged at a height of 0.03-0.2 m above the wind distribution plate 3, and the distance between the heating cores 2 is about 2 times of the diameter of the wind caps or the wind holes and is in the range of 60-160 mm.

In order to increase the residual heat of the inert gas used for fluidization in the melting production process, the residual heat recycling is considered: the argon outlet 8 of each stage of melting furnace is connected to the front pretreatment process (drying and crushing) through an argon output pipeline 9 for waste heat utilization, and then returns to the argon inlet 7 of each stage of melting furnace through an argon input pipeline 10 (see fig. 1). Because part of carbon monoxide gas is generated in the process of producing silicon carbide by melting, the concentration of the carbon monoxide in the high-temperature fluidizing gas is monitored in real time, and the carbon monoxide gas in the argon gas is timely and online overfire and combust to generate carbon dioxide before being recycled to the front pretreatment procedure, so that the production safety of the drying and crushing device is ensured.

The technical scheme of the utility model among, the fluidization inert gas (argon gas) of each level melting furnace all produces the reactant turbulence that promotes the molten state bed through hood aperture and the wind gap on the grid plate 3, and the even flow and the mass transfer heat transfer of bed in the realization bed are promoted to the high velocity gas flow of 25 ~ 55 meters/second. The guide cylinder 4 in each melting furnace further forms reaction material internal circulation in the melting bed layer, and the internal circulation and the external circulation enable the reaction material to be mixed and reacted more uniformly, so that the conversion rate of the generated silicon carbide product is higher. Meanwhile, each fluidized melting furnace is provided with a plurality of groups of graphitized heating cores 2, and the number of the heating cores 2 to be started is accurately controlled according to the type of the product, so that the reaction temperature is ensured.

In the utility model, the silicon carbide product is produced by adopting a multi-furnace series connection grading melting mode, so that the sufficient mixing and mass and heat transfer of materials can be ensured, compared with the traditional melting method and sublimation method, the reaction time for completely producing the qualified silicon carbide product can be shortened from several hours of 15-25 hours in the past to 1-2 hours at present, and the production efficiency is greatly improved; meanwhile, a liquid raw material system is adopted in the preparation of production raw materials, the raw materials are easy to purify and realize high purity (more than 4 nanometers), and meanwhile, the reaction system is fully and uniformly mixed after the raw materials are purified and dried, so that nanoscale silicon carbide powder can be obtained through low-temperature firing, and the crystalline phases (amorphous phase, pure beta phase, pure alpha phase and alpha/beta mixed phase) of the silicon carbide can be accurately controlled by controlling the reaction temperature.

The utility model provides a traditional carborundum production process be intermittent type production and production process material one-way conversion inefficiency a series of problems. In the production process of silicon carbide, a multi-furnace series connection grading melting furnace production mode is applied, so that the mass transfer and heat transfer in the production process of silicon carbide are improved, the complete conversion of a silicon carbide product is realized by one step of reaction, and the separation and reuse of waste materials are not needed; the graphitized heating core 2 is utilized to accurately control the temperature of each bed layer in the furnace or each melting furnace to control the product type; the reaction time of the silicon carbide production process is realized by connecting a plurality of melting furnaces in series; the inert gas is used as the fluidizing gas to generate turbulence in the molten material in the bed layer to realize the uniform mixing and reaction of the material, and the guide cylinder 4 is additionally arranged on the bed layer in the furnace, so that the turbulence degree in the reaction process and the reaction conversion rate of the generated silicon carbide are further improved.

Claims (10)

1. A single-layer multi-furnace melting system is characterized by comprising at least two-stage fluidized melting furnaces, wherein each melting furnace comprises a furnace body (1), a heating core (2), an air distribution plate (3) and a guide cylinder (4), the air distribution plate (3) is arranged at the lower part in the vertically arranged cylindrical furnace body (1), and an air cap or an air hole is fully distributed on the air distribution plate (3); a heating core (2) is arranged on the upper surface close to the air distribution plate (3), and a plurality of guide cylinders (4) which are arranged at intervals and are vertical in the axial direction are arranged above the heating core (2); the upper part and the lower part of the furnace body (1) are respectively provided with a material inlet (5) and a material outlet (6), and the material outlet (6) of the upper-level melting furnace is connected with the material inlet (5) of the lower-level melting furnace through a material conveying pipeline.

2. Single-layer multi-furnace melting system according to claim 1, wherein an argon gas outlet (8) and an argon gas inlet (7) are provided at the top and bottom surfaces of the furnace body (1), respectively.

3. The single-layer multi-furnace melting system of claim 1, wherein the wall of the guide shell (4) is fully provided with through holes, and the diameter of the through holes is 3-6 mm.

4. The single-layer multi-furnace melting system of claim 1, wherein the wind caps or wind holes on the wind distribution plate (3) are circular or regular hexagonal, the diameters of the wind caps are 30-80 mm, and the diameters of the wind holes are 3-8 mm.

5. The single-layer multi-furnace melting system of claim 1 or 4, wherein the central distance between the blast caps or the blast holes is 1.0 to 1.5 times the diameter of the blast caps or the blast holes.

6. The single-layer multi-furnace melting system of claim 1, wherein the guide cylinders (4) are fixed above the air distribution plate (3) by a fixing part at a distance of 0.05-0.10 m, and the distance between the guide cylinders (4) is 3-5 times of the diameter of the guide cylinders.

7. The single-layer multi-furnace melting system according to claim 1, 3 or 6, wherein the height of the guide shell (4) is 0.2-0.6 m, and the diameter of each guide shell (4) is in the range of 0.1-0.3 m.

8. Single-layer multi-furnace melting system according to claim 1, characterized in that the shape and size of the air distribution plate (3) is the same as the cross section of the furnace body (1).

9. The single-layer multi-furnace melting system of claim 1, wherein the cross section of the furnace body (1) is circular, and the inner diameter is 1.0-8.0 m; the heating cores (2) are uniformly arranged along the circular periphery at an alpha angle of 10-90 degrees; the heating core (2) is arranged above the air distribution plate (3) by 0.03-0.2 m.

10. The single-layer multi-furnace melting system of claim 1, wherein the cross section of the furnace body (1) is square, and the side length is 1.0-2.8 m; the heating core (2) is parallel to one side of the square and is uniformly arranged along the vertical side; each heating core (2) is arranged between the rows of the wind caps or the wind holes and is arranged above the wind distribution plate (3) by 0.03-0.2 m, and the distance between the heating cores (2) is 2 times of the diameter of the wind caps or the wind holes.

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