Granular silicon fluidized bed

Abstract

The utility model provides a granular silicon fluidized bed, aiming at solving the technical problems that the existing device is complicated in structure, poor in heat transfer efficiency, low in product quality and incapable of stably running for a long time. The granular silicon fluidized bed comprises a reaction section, an upper section positioned above the reaction section and a lower section positioned below the reaction section, the reaction section is a barrel and comprises a barrel wall, a lining positioned on the inner side of the barrel wall and a heating device positioned on the outer side of the barrel wall; the upper section is provided with a seed crystal feed port and a waste gas outlet, the lower section is provided with a gas inlet and a discharge port, and the gas inlet and the discharge port are communicated with the reaction section through pipelines. The granular silicon fluidized bed disclosed by the utility model is simple in structure, the heating device of the reaction section is arranged on the outer side of the barrel, the barrel wall and the lining are in semi-contact heat transfer, and the expansion section is arranged at the lower end of the reaction section, so that the heat transfer efficiency is greatly improved, the quality and the productivity of products are improved, and the service life and the stability of equipment are prolonged.

Description

TECHNICAL FIELD

[0001] The utility model relates to the production technology field of granular silicon, and particularly relates to a granular silicon fluidized bed. BACKGROUND

[0002] The production principle of granular silicon is to utilize the low decomposition temperature of silane gas, pass "heated hydrogen" and "heated hydrogen and silane gas mixed gas" into a reactor, and simultaneously send micron-sized seeds from the upper part of the reactor, so that the silane gas is thermally decomposed on the surface of the seeds and gradually grows into millimeter-sized particles in a fluidized state. Due to the low thermal decomposition temperature, low molecular weight and specific heat of hydrogen and silane gas, and large specific surface area of the seeds, the production of granular silicon has the advantage of low power consumption, and the key to the production of granular silicon lies in the core equipment, the fluidized bed reactor.

[0003] The structure of the commonly used fluidized bed reactor in the prior art includes a cooling discharge section at the bottom and a heating reaction section at the top, and the structure of the heating reaction section often determines the quality and capacity of the discharged product. Typically, the heating section is divided into three layers or two layers. The Chinese patent with the publication number CN102713001B and the title of "Fluidized bed reactor" discloses a three-layer structure for the heating section, the innermost part is an inner lining layer, the middle part is a metal furnace wall, and the outermost part is a reactor shell layer. An insertion type heating rod is arranged between the metal furnace wall and the reactor shell layer for heating the metal furnace wall. Hydrogen is blown into the reactor through a plurality of straight pipe nozzles extending from the bottom of the reactor. Silane gas and hydrogen are blown into the reactor in the form of a jacket pipe and an inner insertion pipe, respectively. Finally, the fluidization reaction is carried out in the inner lining layer to generate granular silicon products. After the granular silicon products fall into the bottom of the reactor, they will be cooled by the gas blown into the bottom of the reactor, and then the cooled products are discharged from the bottom of the reactor. Although this structure is stable and reliable, it has the following disadvantages: 1. The multi-layer structure is too complex. Heat is transmitted to the reaction materials inside the inner lining through two radiations, which results in low heat transfer efficiency, high requirements for the heating device, easy damage, and limited equipment output to some extent due to the low heat transfer efficiency; 2. The complex structure makes installation and maintenance more complicated, which is not conducive to rapid industrial production and maintenance; 3. The products are cooled inside the reactor, which can easily cause the seeds and fine particles to enter the bottom without being fully fluidized in the heating section at the top, affecting the product quality; 4. The design scheme has more nozzle components inside, which are prone to wear and tear even after coating treatment, causing the products to come into contact with metal, which is not conducive to product quality. The Chinese patent with the publication number CN103842070B and the title of "Preparation of polycrystalline silicon by thermal decomposition of silane in a fluidized bed reactor" discloses a heating section divided into an inner lining layer at the innermost part, an outer shell layer at the outermost part, and a heater between the two layers. This two-layer structure simplifies the equipment, improves the heat transfer efficiency, and has a larger output, but the disadvantage is that the lining layer is prone to leakage during long-term use, and the leaked material comes into contact with the heater, affecting the service life.

[0004] Therefore, how to produce granular silicon fluidized bed with high purity, large output and long-period stable operation of the equipment while simplifying the structure is a technical problem to be solved at present. Practical new type content

[0005] The utility model discloses a granular silicon fluidized bed to solve the technical problem of the complex structure of the existing equipment, low product purity and the inability of the equipment to operate stably for a long period.

[0006] To achieve the above object, the utility model adopts the following technical scheme:

[0007] A granular silicon fluidized bed comprises a reaction section, an upper section above the reaction section and a lower section below the reaction section.

[0008] The reaction section is a cylinder body comprising a cylinder wall, an inner lining on the inner side of the cylinder wall and a heating device on the outer side of the cylinder wall.

[0009] The upper section is provided with a seed crystal feeding port and a waste gas outlet, and the lower section is provided with an air inlet and a discharge port.

[0010] A gap is left between the inner wall surface of the cylinder wall and the outer surface of the inner lining, and a protrusion is arranged in the gap.

[0011] As a preferred technical scheme:

[0012] Optionally, the heating device comprises a heater and a heat preservation layer and is fixedly installed on the outer side of the cylinder body.

[0013] Optionally, the heater is an electric heater comprising a plurality of electric heating rods which are in contact with the cylinder wall and are fixedly installed.

[0014] Optionally, the heater is an induction heater, which is arranged outside the heat preservation layer, and the heat preservation layer is wrapped outside the cylinder wall.

[0015] Optionally, a cooling device is arranged inside and / or outside the upper section, and the cooling mode of the cooling device is gas cooling, jacket cooling or pipe cooling.

[0016] Optionally, the lower section is an enlarged section, and the inner diameter of the enlarged section is greater than that of the reaction section. The purpose of the inner diameter of the enlarged section being greater than that of the reaction section is to realize that the gas of the feed passes through the connecting pipe and is connected with the distributor, and the contact with the metal cylinder wall is as little as possible, thereby improving the product quality; meanwhile, the overall installation, hoisting and maintenance of the distributor are facilitated, and the cleaning of the distributor itself is more favorable, thereby improving the product quality.

[0017] Optionally, the upper section is a hollow cavity, and the inner diameter of the upper section is greater than that of the reaction section and less than that of the enlarged section. The reaction section is a straight cylinder, and the inner diameters of the upper section and the lower section at any positions are greater than that of the reaction section.

[0018] Optionally, the enlarged section is a hollow cavity, and a distributor is arranged inside the enlarged section, the distributor is connected with the bottom end of the reaction section, and the pipelines connected with the gas inlet and the discharge outlet and the reaction section are connected with the distributor.

[0019] Optionally, the connection mode of the pipelines of the gas inlet and the discharge outlet and the distributor is hose connection or expansion joint connection. The connection mode of the present application is not limited to this, and other modes capable of achieving the same purpose are also within the protection scope of the present application.

[0020] Optionally, the protrusions are arranged in an axial direction along the inner wall surface of the cylinder wall and are welded or integrally formed, the protrusions are in contact with the inner liner, and the portions between adjacent protrusions are not in contact with the inner liner; the material of the protrusions is metal, which can be a plurality of sliding grooves arranged at intervals and welded with the inner wall surface, or the inner wall surface of the cylinder wall is a concave-convex surface, that is, the cylinder wall is integrally formed, the protrusions and the inner liner form a semi-contact type, that is, a local contact heat transfer is formed, and the heat transfer efficiency is further improved. The protrusions are in a straight angle shape, a round angle shape or a taper shape, as long as the protrusions protrude from the inner wall surface of the cylinder wall, and the connection mode is within the protection scope of the present application. The protrusions can not be in contact with the inner liner, and the heat transfer efficiency is lower than that when the protrusions are in contact with the inner liner, but the overall heat transfer efficiency is not affected.

[0021] Alternatively, the protrusions are circumferentially distributed along the inner wall surface of the cylinder wall and are welded or integrally formed, the protrusions are in contact with the inner liner, and the portions between adjacent protrusions are not in contact with the inner liner; when the protrusions are circumferentially distributed along the inner wall surface, the protrusions can be in a spiral shape or in a plurality of spaced distribution modes, as long as the protrusions protrude from the inner wall surface of the cylinder wall, which is within the protection scope of the utility model.

[0022] Alternatively, the protrusions are circumferentially distributed along the inner wall surface of the cylinder wall and are welded or integrally formed, the protrusions are in contact with the inner liner, and the portions between adjacent protrusions are not in contact with the inner liner; when the protrusions are circumferentially distributed along the inner wall surface, the protrusions can be in a spiral shape or in a plurality of spaced distribution modes, as long as the protrusions protrude from the inner wall surface of the cylinder wall, which is within the protection scope of the utility model.

[0023] The gap between the inner wall surface of the cylinder wall and the outer surface of the inner liner is 5-150mm, and the size of the gap depends on the thickness of the protrusion (sliding groove). The utility model connects the inner liner and the protrusion in a half-contact mode by arranging a plurality of spaced protrusions on the inner wall surface of the cylinder, which is beneficial to ensure that the inner liner and the cylinder wall have a minimum gap, thereby facilitating the transmission of the heating temperature of the heater to the inside of the reaction section, so as to further improve the quality of the product and the production capacity of the equipment.

[0024] Optionally, the gap between the inner wall surface of the cylinder wall and the outer surface of the inner liner is 8-20mm, and the smaller the gap, the higher the heat transfer efficiency.

[0025] Optionally, the upper section, the reaction section and the lower section are connected by flanges or welding. The connection mode between the three is not limited to this, and other connection modes that can connect the three and ensure that the connection part has no leakage are within the protection scope of the utility model.

[0026] Compared with the prior art, the utility model has the advantages of:

[0027] The granular silicon fluidized bed of the utility model sets the heating device of the heating section outside the shell, which is simple and practical and can quickly produce and maintain and repair; on the other hand, it avoids the technical defects that the original structure is arranged between the liner layer and the shell layer, the non-metallic material liner layer not only bears higher pressure but also has good sealing capacity, so that the material does not leak outside the liner layer, and the use reliability of the liner layer is greatly improved.

[0028] The granular silicon fluidized bed of the utility model improves the heat transfer efficiency by adopting the direct contact type electric heater or the induction heater to directly act on the metal cylinder wall of the reaction section, and further improves the service life of the heater, and simultaneously improves the gas flux of the equipment and the production of the granular silicon; the heater is arranged outside the reactor and is not affected by the atmosphere in the furnace, and is easy to maintain;

[0029] The granular silicon fluidized bed of the utility model improves the purity of the product by arranging the distributor in the enlarged section, and the feed gas and the product outlet are not in contact with the inner wall of the enlarged section, and simultaneously, the enlarged section is not provided with the sweeping pipe port for product cooling, and the setting of the enlarged section of the utility model has lower temperature compared with the reaction section, does not produce large thermal expansion, and is beneficial to the installation and operation of the pipeline at the lower part.

[0030] The granular silicon fluidized bed of the utility model controls the distance between the inner lining and the metal cylinder wall to the minimum by arranging the protrusions in the gap between the inner side of the cylinder wall and the inner lining, and the inner lining and the cylinder wall adopt the semi-contact heat transfer mode, which is beneficial to the substantial improvement of the heat transfer efficiency, and further improves the product quality and the yield.

[0031] The granular silicon fluidized bed of the utility model adopts the non-metallic material for the inner lining in the reaction section, and the inner linings are stacked layer by layer and connected by the sealing glue, which guarantees the minimum distance between the metal cylinder wall and the inner lining, and even if leakage or sealing problems occur during long-term continuous operation, the reaction will not be affected due to the protection of the equipment shell, and the continuous production cycle is improved. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical scheme in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiment or the prior art description will be briefly introduced below, and obviously, the drawings in the following description can obtain other drawings according to the drawings for the ordinary skilled in the art without creating labor.

[0033] Figure 1 It is a structure schematic view of the granular silicon fluidized bed of the utility model embodiment 1;

[0034] Figure 2 It is a structure schematic view of the heating pipe connection mode in the utility model embodiment 1;

[0035] Figure 3 It is Figure 1 It is a transverse sectional view of the inside of the reaction section cylinder wall;

[0036] Figure 4 Figure 2 is a structural schematic diagram of a fluidized bed of granular silicon according to an embodiment of the present application.

[0037] Reference signs:

[0038] 1 - reaction section; 101 - cylinder wall; 102 - inner lining; 103 - heating device; 1031 - heater; 1032 - heat preservation layer; 104 - protrusion; 2 - upper section; 201 - seed crystal feeding port; 202 - waste gas outlet; 203 - cooling device; 3 - lower section; 301 - gas inlet; 302 - discharge port; 303 - distributor; 304 - mounting hole. DETAILED DESCRIPTION

[0039] Hereinafter, only certain exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the drawings and the description are considered to be exemplary in nature rather than limiting.

[0040] In the description of the present application, it is to be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly understood by those skilled in the art, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0041] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0042] In the utility model, unless another definite provision and limitation, the terms "mount", "link", "connect", "fix" and so on should do broad sense understanding, for example, can be fixed connection, also can be detachable connection, or be integrated;Can be mechanical connection, also can be electric connection, still can be communication;Can be direct connection, also can through intermediate medium indirectly connect, can be the intercommunication of two elements or the interaction of two elements.For the ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to specific circumstances.

[0043] In the utility model, unless another definite provision and limitation, the first feature is "on" or "under" the second feature can include that the first and second features are in direct contact, or the first and second features are not in direct contact but are in contact through another feature between them.Moreover, the first feature "on", "above" and "on the surface of" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature.The first feature "under", "below" and "under" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0044] The following disclosure provides many different embodiments or examples for implementing different structures of the utility model.For the purpose of simplifying the disclosure of the utility model, the components and settings of specific examples are described in the following.Their purpose is not to limit the utility model, of course, and they are only examples.In addition, the utility model can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, and it does not indicate the relationship between the various embodiments and / or settings discussed per se.In addition, the utility model provides various specific examples of processes and materials, but the ordinary skilled in the art can realize the application of other processes and / or the use of other materials.

[0045] The embodiments of the utility model will be described in detail below with reference to the drawings. Embodiment 1

[0046] The utility model embodiment provides a kind of granular silicon fluidized bed, including reaction section 1, upper section 2 located above reaction section 1, and lower section 3 located below reaction section 1;

[0047] As Figure 1As shown, the reaction section 1 is a cylinder body, including a cylinder wall 101, an inner liner 102 located on the inner side of the cylinder wall 101, and a heating device 103 located on the outer side of the cylinder wall 101. The cylinder wall 101 is a metal cylinder wall. The heating device 103 includes a heater 1031 and a heat preservation layer 1032, which are fixedly installed on the outer side of the cylinder wall 101. Specifically, the heater 1031 is an electric heater, which includes a plurality of electric heating rods and is fixedly installed in close contact with the cylinder wall 101 through a plurality of groups of bolts or screws. As shown in Figure 2 The heat preservation layer 1032 is wrapped outside the electric heater. A gap is left between the inner wall surface of the cylinder wall 101 and the outer surface of the inner liner 102, and a protrusion 104 is arranged in the gap. The protrusion 104 is fixedly connected or integrally formed with the inner wall surface of the cylinder wall 101 or the outer surface of the inner liner 102. Specifically, as shown in Figure 3 The protrusion has a plurality of strips, which are distributed axially along the inner wall surface of the cylinder wall 101 and are welded or integrally formed. The protrusion 104 is in contact with the inner liner 102, as shown in Figure 3 The part between adjacent protrusions is not in contact with the inner liner 102, as shown in Figure 3 b of FIG. 2.

[0048] The gap between the inner wall surface of the cylinder wall 101 and the outer surface of the inner liner 102 is 5-150 mm, and preferably 6-20 mm.

[0049] The upper section 2 is provided with a seed crystal feeding port 201 and a waste gas outlet 202. The seed crystal feeding port 201 and the waste gas outlet 202 can be simultaneously provided at the top or the side of the upper section 2, or one can be provided at the top and the other can be provided at the side. The specific design can be made according to the actual use. A cooling device 203 is further provided inside and / or outside the upper section 2. Specifically, the cooling device can be provided outside the upper section wall, and the cooling medium can be delivered to the inside of the upper section through an opening. Alternatively, the cooling device can be provided inside, and the delivery of the cooling medium can be controlled by a valve outside. Alternatively, the cooling device can be installed inside and outside at the same time. The specific design can be made according to the actual use. The cooling mode of the cooling device 203 is gas cooling, jacket cooling, or companion pipe cooling. The upper section 2 is an internally hollow cavity, and its inner diameter is greater than the inner diameter of the reaction section 1 and less than the inner diameter of the enlarged section 3.

[0050] The lower section 3 is an enlarged section, which is an internally hollow cavity. An air inlet 301 and a discharge port 302 are provided on the lower section 3. The air inlet and the discharge port are connected to the reaction section 1 through pipelines. A distributor 303 is further provided inside the enlarged section. The distributor 303 is connected to the bottom end of the reaction section 1. The pipelines connected to the reaction section 1 through the air inlet 301 and the discharge port 302 are connected to the distributor 303. The connection mode of the pipelines of the air inlet 301 and the discharge port 302 to the distributor 303 is soft pipe connection or expansion joint connection, as shown in Figure 1As shown in Fig. 2, the inner diameter of the enlarged section is larger than that of the reaction section 1. A mounting hole 304 is arranged on the wall of the enlarged section, which facilitates the installation of the gas inlet pipeline and the discharge pipeline and the maintenance and replacement of the inner liner.

[0051] The upper section 2, the reaction section 1 and the lower section 3 are connected by flanges or welded. Example 2

[0052] A fluidized bed of granular silicon, which is basically the same as that in Example 1, except that the type and installation mode of the heater are different, as shown in Fig. 3. Figure 4 As shown in Fig. 3, the heater 1031 in the heating device 103 is an induction heater, which is arranged outside the heat preservation layer 1032, and the heat preservation layer 1032 is wrapped outside the cylinder wall 101. Example 3

[0053] A fluidized bed of granular silicon, which is basically the same as that in Example 1, except that the arrangement mode of the protrusions is different, specifically, there are a plurality of protrusions, which are distributed along the circumferential direction of the inner wall of the cylinder wall and are fixed by welding or one-piece forming, or there is only one protrusion, which is fixed in a spiral form along the inner wall of the cylinder wall. Example 4

[0054] A fluidized bed of granular silicon, which is basically the same as that in Example 1, except that the arrangement mode of the protrusions is different, specifically, the protrusions are arranged on the outer surface of the inner liner and are distributed along the axial direction or the axial direction of the outer surface of the inner liner, and the distribution mode is the same as that in Example 1 and Example 3, and the protrusions and the inner liner are arranged in one-piece forming.

[0055] The device has the advantages of simple structure, high heat transfer efficiency, the setting of the bottom enlarged section ensures that the raw material gas does not contact the wall of the metal material, and facilitates the installation and operation of the lower pipeline, has the advantages of high yield, good product quality, long operation cycle and stability.

Claims

1. A fluidized bed of particulate silicon, characterized by: The reactor comprises a reaction section, an upper section above the reaction section, and a lower section below the reaction section; The reaction section is a cylinder body comprising a cylinder wall, an inner liner inside the cylinder wall, and a heating device outside the cylinder wall; The upper section is provided with a seed crystal feeding port and a waste gas outlet, and the lower section is provided with a gas inlet and a discharge port, which are communicated with the reaction section through pipelines; The inner wall surface of the cylinder wall and the outer surface of the inner liner are spaced apart by a gap and provided with protrusions in the gap, which are fixedly connected or integrally formed with the inner wall surface of the cylinder wall or the outer surface of the inner liner.

2. A fluidized bed of granular silicon as claimed in claim 1, characterized in that: The heating device comprises a heater and a heat preservation layer, which are fixedly installed outside the cylinder body, and the cylinder wall is a metal cylinder wall.

3. A fluidized bed of granular silicon as claimed in claim 2, characterized in that: The heater is an electric heater comprising a plurality of electric heating rods, which are attached to and fixedly installed on the cylinder wall, and the heat preservation layer is wrapped outside the electric heater.

4. A fluidized bed of granular silicon as claimed in claim 2, characterized in that: The heater is an induction heater, which is arranged outside the outer layer of the heat preservation layer, and the heat preservation layer is wrapped outside the cylinder wall.

5. A fluidized bed of granular silicon as defined in claim 1, characterized in that: A cooling device is further arranged inside and / or outside the upper section, and the cooling device is cooled by gas cooling, jacket cooling, or pipe cooling.

6. A fluidized bed of granular silicon as defined in claim 1, characterized in that: The lower section is an enlarged section, and the inner diameter of the enlarged section is greater than that of the reaction section.

7. A fluidized bed of granular silicon as claimed in claim 6, characterized in that: The upper section is a hollow cavity, and the inner diameter of the upper section is greater than that of the reaction section and less than that of the enlarged section.

8. A fluidized bed of granular silicon as defined in claim 6, characterized in that: The enlarged section is a hollow cavity, and a distributor is arranged inside the enlarged section, the distributor is connected to the bottom end of the reaction section, and the pipelines of the gas inlet and the discharge port connected to the reaction section are connected to the distributor.

9. A fluidized bed of granular silicon as claimed in claim 8, characterized in that: The connection mode of the pipelines of the gas inlet and the discharge port to the distributor is hose connection or expansion joint connection.

10. A fluidized bed of granular silicon as defined in claim 1, wherein: The protrusions are a plurality of strips, which are axially distributed along the inner wall surface of the cylinder wall and are welded or integrally formed, the protrusions are in contact with the inner liner, and the portions between adjacent protrusions are not in contact with the inner liner. Alternatively, the protrusions are circumferentially distributed along the inner wall surface of the cylinder wall and are welded or integrally formed, the protrusions are in contact with the inner liner, and the portions between adjacent protrusions are not in contact with the inner liner. Alternatively, the protrusions are a plurality of strips, which are axially or circumferentially distributed along the outer surface of the inner liner and are integrally formed, the protrusions are in contact with the inner wall surface of the cylinder wall, and the portions between adjacent protrusions are not in contact with the cylinder body.

11. A fluidized bed of granular silicon as defined in claim 1, characterized in that: The gap between the inner wall surface of the cylinder wall and the outer surface of the inner liner is 5-150 mm.

12. A fluidized bed of granular silicon as defined in claim 1, characterized in that: The gap between the inner wall surface of the cylinder wall and the outer surface of the inner liner is 6-20 mm.

13. A fluidized bed of granular silicon as defined in claim 1, characterized in that: The upper section, the reaction section, and the lower section are connected by flanges or welding.

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