Fluidized bed reactor and process for preparing granular silicon by using fluidized bed reactor

Abstract

The invention provides a fluidized bed reactor and a process for preparing granular silicon by using the fluidized bed reactor, and aims to solve the problem that a lining is easy to damage due to the difference of thermal expansion coefficients between a metal shell and a non-metal lining in the prior art. The fluidized bed reactor comprises a cylinder, a seed crystal feed port, a waste gas outlet, a gas inlet and a discharge port, the seed crystal feed port and the waste gas outlet are formed in the top of the cylinder, the gas inlet and the discharge port are formed in the bottom of the cylinder, the cylinder comprises a shell and a lining, the lining is formed by mutually lapping a plurality of sub-liners, and a gap area is formed at the lapping part; a first opening and a second opening on the same cross section or different cross sections are formed along two sides of the inner wall and the outer wall of the lining; and the plurality of sub linings are fixedly connected with the shell respectively. The fluidized bed reactor for preparing the granular silicon is beneficial to improving the quality of the granular silicon. The fluidized bed reactor disclosed by the invention is simple in structure, not only ensures that a product is not contacted with metal, but also effectively solves the problem of thermal expansion difference between the non-metal lining and the metal shell, and improves the equipment reliability while ensuring the product quality.

Description

Technical Field

[0001] The present invention relates to the technical field of granular silicon production, and in particular to a fluidized bed reactor and a process for preparing granular silicon therefrom. Background Art

[0002] The production principle of granular silicon is to use the low decomposition temperature of silane gas to pass "heated hydrogen" and "heated hydrogen and silane gas mixture" into the reactor, and at the same time send micron-sized seed crystals from the top of the reactor. Silane gas is thermally decomposed on the surface of the seed crystal, 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 ​​seed crystals, granular silicon production has the advantage of low power consumption, and the key to granular silicon production lies in its core equipment, the fluidized bed reactor.

[0003] The structure of the commonly used fluidized bed reactor in the prior art includes a feeding section at the top, a heating reaction section in the middle, and a discharging section at the bottom. The structure of the heating reaction section often determines the quality and production capacity of the discharging product. It is usually represented by a three-layer reaction section structure represented by REC Silicon INC and a two-layer structure represented by MEMC Electronic Materials Co., Ltd. Regardless of the structure, due to the purity requirements of the granular silicon product, the reaction cannot be carried out directly in the steel cylinder, but needs to be carried out in a non-metallic clean lining material. There is a difference in thermal expansion coefficient between the non-metallic lining and the steel cylinder material, so it is necessary to take measures to eliminate thermal expansion stress between the lining material and the steel equipment. Among them, REC Silicon INC's publication number is CN102713001B. The Chinese patent named Fluidized Bed Reactor discloses a method of adding a bellows to the lining to eliminate thermal expansion stress. Such a design makes the equipment complicated to manufacture and is extremely easy to be damaged during installation. In addition, the lining is easily damaged due to the shaking of the lining during the operation of the equipment; each star company has a publication number of CN 107592825 B, a Chinese invention patent entitled Clamping Device for Reactor System discloses a solution to this problem, which sets a bellows on the top of the cylinder. When the reaction zone is heated to a high temperature greater than 600°C, the lining material expands and presses against the reactor outlet flange cover at the top, so the bellows extends. This solution causes the lining material to be subjected to great stress. This benefit is more obvious when the equipment design pressure is high, so the lining is required to have sufficient thickness and strength, which in turn leads to an increase in the cost of the lining material. Regardless of the technical route, these measures often complicate the equipment manufacturing. Due to the vibration of the fluidized reaction itself, it is easy to cause equipment vibration, excessive stress on the lining material or damage.

[0004] Therefore, it is an urgent technical problem to develop a fluidized bed reactor that can effectively solve the difference in thermal expansion coefficients between the metal shell and the non-metallic lining, improve product quality and equipment reliability, and use the fluidized bed reactor to prepare high-quality granular silicon. Summary of the invention

[0005] The object of the present invention is to provide a fluidized bed reactor and a process for preparing granular silicon, so as to solve the problem that the existing equipment cannot effectively solve the problem that the lining is easily damaged due to the difference in thermal expansion coefficient between the metal shell and the non-metallic lining.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A fluidized bed reactor comprises a cylinder, a seed crystal feed port and a waste gas outlet arranged at the top of the cylinder, and an air inlet and a discharge port arranged at the bottom of the cylinder, characterized in that: the cylinder comprises an outer shell and an inner liner, the inner liner is formed by overlapping a plurality of sub-liners, a gap region is formed at the overlapping position, the gap region is provided with a first opening and a second opening on the same cross section or different cross sections along the inner wall and the outer wall of the inner liner; the plurality of sub-liners are respectively fixedly connected to the outer shell. The present invention adopts a method of overlapping a plurality of sub-liners and leaving a gap at the overlapping position, and also leaving a gap between the outer shell and the inner liner. Under the high temperature environment of the reactor, when each sub-liner is heated, it can expand toward the gap position at the overlapping position and the gap position between the outer shell, and the metal shell can also expand toward the gap between the inner liner after being heated, thereby solving the problem that the liner is easily damaged due to the difference in thermal expansion coefficient between the metal shell and the non-metallic liner. The first opening and the second opening arranged at the gap position of the present invention can be located at the same cross section or different cross sections, as long as it is ensured that the material does not directly contact the metal shell through the gap region.

[0007] As the preferred technical solution: Optionally, the multiple sub-linings are overlapped with each other to form a continuous wall, and the overlapping methods include step type, tongue and groove type, bevel type or tooth type, etc.; the fixed connection refers to the circumferential connection between each sub-lining and the metal shell by bolts or pins. The overlapping and fixed connection methods of the present invention are not limited to this. Other methods that can achieve a certain gap between multiple sub-linings and form a continuous wall, as well as methods that fix the liner and the shell and facilitate the replacement and maintenance of the liner, all fall within the protection scope of the present invention.

[0008] Optionally, when the fixed connection is a bolt connection, the multiple sub-linings are provided with multiple slots arranged along the circumferential direction of the lining away from the overlapped parts, the slot bottoms are provided with through holes, the inner wall surface of the shell is provided with receiving parts corresponding to the slots, and the solder or screws are connected to the receiving parts through the through holes to achieve fixation. The bolts can be metal bolts or non-metallic bolts, and the bolt surface can be provided inside the slots or can be connected to the outside of the slots.

[0009] Optionally, the outer shell is a metal shell, and the lining is a non-metallic lining. The interior of the non-metallic lining is a cavity, which includes a feed section, a reaction section, and a discharge section from top to bottom. The seed crystal feed port and the exhaust gas outlet are arranged on the feed section, and the reaction section is provided with a heating device, and the heating device is fixedly installed on the outside of the outer shell; a distributor is provided in the discharge section, and the air inlet and the discharge port are both provided on the distributor.

[0010] Optionally, the distributor comprises: A flange plate, the edge of which is provided with a plurality of flange connection holes along the circumferential direction and is connected to the bottom flange of the housing by bolts; An air intake chamber is arranged on one side of the flange plate and is formed integrally with the flange plate, and an annular partition is arranged inside the air intake chamber to divide the air intake chamber into a concentric inner air intake chamber and an outer air intake chamber; An air inlet, divided into an inner air inlet and an outer air inlet, the inner air inlet is communicated with the inner air inlet chamber, and the outer air inlet is communicated with the outer air inlet chamber, for different reaction gases to enter the air inlet chamber; A discharge port is arranged at the top of the air inlet chamber, the discharge port is connected to a discharge pipe, and the discharge pipe passes through the middle of the air inlet chamber and extends out of the air inlet chamber; An air inlet hole is arranged at the top of the air inlet chamber, and is used to allow the reaction gas in the air inlet chamber to enter the reaction section through the air inlet hole. The air inlet holes are composed of a plurality of inner ring air inlet holes and an outer ring air inlet holes. The inner ring air inlet holes correspond to the position of the inner air inlet chamber, and the outer ring air inlet holes correspond to the position of the outer air inlet chamber.

[0011] Optionally, the air inlet chamber is arranged above the flange plate and extends into the cylinder, the inner air inlet and the outer air inlet are arranged on the flange plate, and the air inlet hole is arranged on the air inlet chamber and located at the top position.

[0012] Optionally, the air intake chamber is arranged below the flange plate and outside the cylinder body, the inner air inlet is arranged on the inner air intake chamber and at the bottom position, the outer air inlet is arranged on the outer air intake chamber and at the bottom position, and the air intake hole is arranged on the flange plate.

[0013] Optionally, the heating device includes a heater and a thermal insulation layer; The heater is an electric heater, including a plurality of electric heating rods, which are fitted and fixedly installed on the outer wall surface of the cylinder, and the insulation layer is wrapped around the electric heater; Alternatively, the heater is an induction heater, which is arranged on the outer layer of the thermal insulation layer, and the thermal insulation layer is wrapped outside the cylinder.

[0014] Optionally, the gap between the inner wall surface of the outer shell and the outer surface of the lining is 5~150mm, specifically 6~20mm.

[0015] The present invention also provides a process for preparing granular silicon, which is carried out using the fluidized bed reactor as described above and comprises the following steps: 1) Turn on the heating device located outside the cylinder so that the temperature of the heating area of ​​the reaction section is 600° C. to 800° C. Synchronously, the process gas enters the inner air inlet chamber and the outer air inlet chamber through the inner air inlet port and the outer air inlet port of the distributor respectively, and enters the reaction section of the fluidized bed reactor through the inner ring air inlet hole and the outer ring air inlet hole above the inner air inlet chamber and the outer air inlet chamber; 2) The seed crystal silicon enters the fluidized bed reactor through the seed crystal feed port, the composition and ratio of the process gas are changed, and the process gas drives the seed crystal to react in a fluidized state; 3) After the fluidization inside the fluidized bed reactor becomes stable, the reaction is carried out in the heating area, and the seed silicon grows to become product granular silicon, which is discharged from the outlet of the distributor, and the tail gas after the reaction is discharged through the waste gas outlet of the feed section.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The non-metallic lining of the present invention adopts a special overlapping structure, leaving a gap at the overlapping position, and the heater is arranged at the outermost side of the cylinder, so that the smallest gap is retained between the outer shell and the lining, which greatly improves the heat transfer efficiency. The lining is fixed to the inner wall of the outer shell by metal or non-metallic bolts away from the overlapping position, so that under the heating state, the lining and the outer shell can expand freely respectively. The whole equipment does not need bellows or springs to eliminate thermal expansion stress, which completely solves the problem of inconsistent expansion caused by different thermal expansion coefficients between the metal shell and the non-metallic lining material, and the structure is simple and reliable.

[0017] 2. The present invention makes the distributor and the flange plate (or flange cover) at the bottom of the equipment into an integral whole (divided into upward and downward types, the upward one is that the distribution plate and the bottom flange cover are made into an integral whole, and the feed gas is connected to the flange cover; the downward one is that a small section of the cylinder is designed under the flange, and the feed gas is connected to the section of the cylinder), and the cold and hot fluids use an annular partition to separate the air intake chamber into concentric inner air intake chamber and outer air intake chamber, realizing independent feeding, abandoning various complex distributor structures, the equipment is simple, reliable, and easy to maintain.

[0018] 3. The present invention changes the heating device of the heating section from being installed inside the cylinder in the prior art to being installed outside the cylinder. On the one hand, this structure is simple, practical and can be quickly produced and repaired; on the other hand, it avoids the technical defects of the original structure in which the lining layer is arranged between the lining layer and the outer shell layer, which requires the lining layer of non-metallic materials to withstand higher pressure and have better sealing ability, so that the material will not leak to the outside of the lining layer and contact the wall of the metal outer shell, which greatly improves the reliability of the lining and the lining is formed by overlapping sections, thereby increasing the service life of the lining.

[0019] 4. The present invention controls the gap between the liner and the shell within the range of 5 to 150 mm, which is smaller than the prior art and has higher heat transfer efficiency.

[0020] 5. The present invention improves the heat transfer efficiency by using a direct contact electric heater or an induction heater to directly act on the metal casing of the reaction section, thereby increasing the service life of the heater, while also increasing the gas flux of the equipment and the yield of granular silicon; the heater is placed outside the reactor, is not affected by the atmosphere in the furnace, and is also easy to inspect and maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a structural schematic diagram of the fluidized bed reactor of the present invention; Figure 2 for Figure 1 The enlarged structural diagram at A in the middle; Figure 3 (a) to (d) are Figure 2 An enlarged structural schematic diagram of different overlapping modes at the overlapping position; Figure 4 for Figure 2 The enlarged structural diagram at a in the middle; Figure 5 for Figure 2 The enlarged structural diagram at b in the middle; Figure 6 This is a schematic diagram of the installation structure when the heating device of the present invention adopts an electric heater; Figure 7 This is a schematic diagram of the installation structure when the heating device of the present invention adopts an induction heater; Figure 8 It is a structural schematic diagram of the distributor of the present invention; Fig. 9 It is a schematic diagram of the installation structure when the distributor of the present invention is located outside the cylinder; Reference numerals: 1-cylinder; 101-shell; 102-lining; 103-slot; 104-threaded hole; 105-receiving part; 106-through hole; 2-seed crystal feed port; 3-waste gas outlet; 4-air inlet; 401 inner ring air inlet hole; 402-outer ring air inlet hole; 5-discharge port; 6-heating device; 601-heater; 602-insulation layer; 6011-electric heating rod; 7-distributor; 701-flange plate; 702-inlet chamber; 7021-inner air inlet chamber; 7022-outer air inlet chamber; 703-annular partition; 704-inlet; 7041-inner air inlet; 7042-outer air inlet; 11-overlapping part; 1101-first opening; 1102-second opening. DETAILED DESCRIPTION

[0023] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the products of the present invention are conventionally placed when used, or are the orientations or positional relationships conventionally understood by those skilled in the art, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0025] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0026] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0028] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0029] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] This embodiment provides a fluidized bed reactor such as Figure 1 As shown, it comprises a cylinder 1, a seed crystal feed port 2 and a waste gas outlet 3 arranged at the top of the cylinder, and an air inlet 4 and a discharge port 5 arranged at the bottom of the cylinder.

[0031] The cylinder 1 comprises an outer shell 101 and an inner liner 102. Figure 2 As shown, the lining 102 is formed by a plurality of sub-linings overlapping each other, that is, the sub-linings are installed from top to bottom along the inner wall of the shell, and the number of sub-linings is 3 to 5, which are overlapped with each other, and a plurality of sub-linings are overlapped to form a continuous wall surface, and the overlapping portion is defined as an overlapping portion 11, and each sub-lining has one or two overlapping portions, that is, the sub-linings located at both ends of the cylinder have one overlapping portion, and the sub-lining located in the middle has two overlapping portions.

[0032] The gap area is provided with a first opening and a second opening on the same or different cross-sections along both sides of the inner wall and the outer wall of the lining, that is, the overlap portion 11 is provided with a first opening 1101 and a second opening 1102 along the L direction, and its structure includes a step type, a tongue and groove type, a slope type and a tooth connection type, as shown in Figures 3 (a), (b), (c) and (d), wherein Figure 3 (a) shows a step type, and in the embodiment of the present invention, the step-type overlap mode is not limited to the one-step type shown in the figure, and can also be a two-step type or more than two-step type; Figure 3 (b) shows a tongue and groove type, Figure 3 (c) shows a slope type, and Figure 3 (d) shows a tooth connection type. The structural form of the overlap portion in the embodiment of the present invention is not limited to the above four types, and can also be a combination of a step type and a slope type, or a combination of a step type and a tooth connection type, etc. As long as the gap area is formed between the two adjacent sub-linings and the product is not in direct contact with the inner wall of the metal shell, it is within the scope shown in this embodiment.

[0033] The two overlapping sub-linings partially overlap at the overlapping part, and the length of the overlapping part is set to h, which is controlled in the range of 5~100mm. The purpose is to prevent the particles reacting in the fluidized state inside the non-metallic lining from contacting the metal shell. A gap area d is formed between the overlapping parts, and the gap d is controlled in the range of 2~30mm. The purpose is to eliminate the difference in thermal expansion caused by the different thermal expansion coefficients between the non-metallic lining and the metal cylinder wall, so that both the metal shell and the liner can expand freely.

[0034] Each sub-liner is connected to the metal shell by bolts or pins along the circumferential direction, such as Figure 2 As shown at a and b in the figure, when the fixed connection is a bolt connection, a plurality of slots 103 arranged along the circumferential direction of the liner are provided on the plurality of sub-liners away from the overlapping parts, as shown in FIG. Figure 4 As shown, a threaded hole 104 is provided at the bottom of the slot, and a receiving portion 105 corresponding to the slot is provided on the inner wall surface of the housing. Solder or screws pass through the threaded hole 104 and connect with the receiving portion 105 to achieve fixation. When the fixed connection is a riveting or pin connection, as shown in FIG. Figure 5As shown, multiple sub-linings are provided with multiple through holes 106 arranged along the circumferential direction of the lining away from the overlapping parts, and rivets or pins are fixedly connected to the receiving part 105 after passing through the through holes 106. When multiple sub-linings are overlapped and respectively fixed to the inner wall surface of the shell, the gap between the outer surface of the lining and the inner wall surface of the shell is 5-150 mm, preferably 6-20 mm.

[0035] The outer shell is a metal shell, and the inner lining is a non-metallic lining. The interior of the non-metallic lining is a cavity, which includes a feed section, a reaction section, and a discharge section from top to bottom. The seed crystal feed port and the exhaust gas outlet are arranged on the feed section. The reaction section is provided with a heating device 6, which is fixedly installed on the outside of the cylinder 1 (that is, the outer shell 101). The heating device includes a heater 601 and a heat preservation layer 602. Figure 1 As shown, the heater is an electric heater, including a plurality of electric heating rods 6011, which are fitted and fixedly installed on the outer wall of the cylinder 1. Figure 6 As shown, the insulation layer 602 is wrapped around the electric heater 601; As another preferred embodiment, the heater 601 is an induction heater, such as Figure 7 As shown, it is arranged on the outer layer of the thermal insulation layer 602 , and the thermal insulation layer 602 is wrapped outside the cylinder 1 .

[0036] A distributor 7 is provided in the discharging section. Figure 1 and 8 As shown, the air inlet 4 and the discharge port 5 are both arranged on the distributor, wherein the distributor comprises: The flange plate 701 has a plurality of flange connection holes arranged circumferentially at its edge and is connected to the bottom flange of the housing 101 by bolts; The air inlet chamber 702 is arranged on one side of the flange plate 701 and is formed integrally with the flange plate 701. An annular partition plate 703 is arranged inside the air inlet chamber 702 to separate the air inlet chamber 702 into a concentric inner air inlet chamber 7021 and an outer air inlet chamber 7022. The air inlet 704 is divided into an inner air inlet 7041 and an outer air inlet 7042. The inner air inlet 7041 is connected to the inner air inlet chamber 7021, and the outer air inlet 7042 is connected to the outer air inlet chamber 7022, so as to allow different reaction gases to enter the air inlet chamber; The discharge port 5 is arranged at the top of the air inlet chamber 702, and the discharge port is connected to the discharge pipe, which passes through the middle of the air inlet chamber and extends out of the air inlet chamber; The air inlet hole 4 is arranged at the top of the air inlet chamber 702, and is used to allow the reaction gas in the air inlet chamber to enter the reaction section through the air inlet hole. The air inlet holes are composed of several circles of inner ring air inlet holes 401 and outer ring air inlet holes 402. The inner ring air inlet holes correspond to the position of the inner air inlet chamber, and the outer ring air inlet holes correspond to the position of the outer air inlet chamber.

[0037] There are two installation positions for the distributor, namely upward setting and downward setting, as follows: When the distributor 7 is set upward, as Figure 1 As shown, the air inlet chamber is arranged above the flange plate and extends into the cylinder body, the inner air inlet and the outer air inlet are arranged on the flange plate, and the air inlet hole is arranged on the air inlet chamber and located at the top position.

[0038] When the distributor 7 is set downward, as Fig. 9 As shown, the air intake chamber is arranged below the flange plate and outside the cylinder 1, the inner air intake port is arranged on the inner air intake chamber and at the bottom position, the outer air intake port is arranged on the outer air intake chamber and at the bottom position, and the air intake hole is arranged on the flange plate.

[0039] This embodiment also provides a process for preparing granular silicon, which is carried out using the above-mentioned fluidized bed reactor and includes the following steps: 1) Turn on the heating device located outside the cylinder so that the temperature of the heating area of ​​the reaction section is 600°C to 800°C. Synchronously, the process gas enters the inner air inlet chamber and the outer air inlet chamber through the inner air inlet port and the outer air inlet port of the distributor respectively, and enters the reaction section of the fluidized bed reactor through the inner ring air inlet hole and the outer ring air inlet hole above the inner air inlet chamber and the outer air inlet chamber; 2) After the seed crystal silicon enters the fluidized bed reactor through the seed crystal feed port of the feed section, the composition and ratio of the process gas are changed, and the process gas drives the seed crystal to react in a fluidized state; 3) After the fluidization inside the fluidized bed reactor becomes stable, the reaction is carried out in the heating area, and the seed silicon grows to become product granular silicon, which is discharged from the outlet of the distributor, and the tail gas after the reaction is discharged through the waste gas outlet of the feed section.

[0040] The device of the present invention has a simple structure. The non-metallic lining adopts a special overlap structure, so that the lining and the shell can expand freely under heating. The whole device does not need bellows or springs to eliminate thermal expansion stress, which effectively solves the technical problems of easy damage and low service life of the lining caused by the difference in thermal expansion coefficient between the metal shell and the non-metallic lining material. The structure is simple and reliable. The heater is arranged on the outermost side of the cylinder to minimize the distance between the shell and the lining, which greatly increases the heat transfer efficiency. The granular silicon prepared by the device of the present invention is of good quality and can be widely used.

Claims

1. A fluidized bed reactor, comprising a cylinder, a seed crystal feed port and a waste gas outlet arranged at the top of the cylinder, and an air inlet and a discharge port arranged at the bottom of the cylinder, characterized in that: The cylinder body includes an outer shell and an inner lining, wherein the inner lining is formed by a plurality of sub-linings overlapping each other, a gap area is formed at the overlapping portion, and the gap area is provided with a first opening and a second opening on the same cross-section or different cross-sections along both sides of the inner wall and the outer wall of the lining; the plurality of sub-linings are respectively fixedly connected to the outer shell.

2. A fluidized bed reactor according to claim 1, characterized in that: The multiple sub-linings are overlapped with each other to form a continuous wall surface, and the overlapping methods include step type, tongue and groove type, bevel type or tooth type; the fixed connection refers to the connection between each sub-lining and the metal shell along the circumferential direction through bolts or pins.

3. A fluidized bed reactor according to claim 2, characterized in that: When the fixed connection is a bolt connection, a plurality of slots arranged along the circumferential direction of the liner are provided on the plurality of sub-liners away from the overlapping parts, a through hole is provided at the bottom of the slot, and a receiving portion corresponding to the slot is provided on the inner wall surface of the outer shell, and the bolts are connected to the receiving portion through the through hole to achieve fixation.

4. A fluidized bed reactor according to claim 1, characterized in that: The outer shell is a metal shell, and the inner lining is a non-metallic lining. The interior of the non-metallic lining is a cavity, which includes a feed section, a reaction section, and a discharge section from top to bottom. The seed crystal feed port and the exhaust gas outlet are arranged on the feed section. The reaction section is provided with a heating device, and the heating device is fixedly installed on the outside of the outer shell; a distributor is provided in the discharge section, and the air inlet and the discharge port are both provided on the distributor.

5. A fluidized bed reactor according to claim 4, characterized in that: The distributor comprises: A flange plate, the edge of which is provided with a plurality of flange connection holes along the circumferential direction and is connected to the bottom flange of the housing by bolts; An air intake chamber is arranged on one side of the flange plate and is formed integrally with the flange plate, and an annular partition is arranged inside the air intake chamber to divide the air intake chamber into a concentric inner air intake chamber and an outer air intake chamber; An air inlet, divided into an inner air inlet and an outer air inlet, the inner air inlet is communicated with the inner air inlet chamber, and the outer air inlet is communicated with the outer air inlet chamber, for different reaction gases to enter the air inlet chamber; A discharge port is arranged at the top of the air inlet chamber, the discharge port is connected to a discharge pipe, and the discharge pipe passes through the middle of the air inlet chamber and extends out of the air inlet chamber; An air inlet hole is arranged at the top of the air inlet chamber, and is used to allow the reaction gas in the air inlet chamber to enter the reaction section through the air inlet hole. The air inlet holes are composed of a plurality of inner ring air inlet holes and an outer ring air inlet holes. The inner ring air inlet holes correspond to the position of the inner air inlet chamber, and the outer ring air inlet holes correspond to the position of the outer air inlet chamber.

6. A fluidized bed reactor according to claim 5, characterized in that: The air inlet chamber is arranged above the flange plate and extends into the cylinder body, the inner air inlet and the outer air inlet are arranged on the flange plate, and the air inlet hole is arranged on the air inlet chamber and located at the top position.

7. A fluidized bed reactor according to claim 5, characterized in that: The air intake chamber is arranged below the flange plate and outside the cylinder body, the inner air intake port is arranged on the inner air intake chamber and at the bottom position, the outer air intake port is arranged on the outer air intake chamber and at the bottom position, and the air intake hole is arranged on the flange plate.

8. A fluidized bed reactor according to claim 4, characterized in that: The heating device comprises a heater and a heat-insulating layer; The heater is an electric heater, including a plurality of electric heating rods, which are fitted and fixedly installed on the outer wall surface of the cylinder, and the insulation layer is wrapped around the electric heater; Alternatively, the heater is an induction heater, which is arranged on the outer layer of the thermal insulation layer, and the thermal insulation layer is wrapped outside the cylinder.

9. A fluidized bed reactor according to claim 1, characterized in that: The gap between the inner wall surface of the shell and the outer surface of the lining is 5 to 150 mm, specifically 6 to 20 mm.

10. A process for preparing granular silicon, characterized in that: The method is carried out using a fluidized bed reactor as claimed in any one of claims 1 to 9, comprising the following steps: The heating device located outside the cylinder is turned on so that the temperature of the heating area of ​​the reaction section is 600° C. to 800° C., and the process gas enters the inner air inlet chamber and the outer air inlet chamber through the inner air inlet and the outer air inlet of the distributor respectively, and enters the reaction section of the fluidized bed reactor through the inner ring air inlet hole and the outer ring air inlet hole above the inner air inlet chamber and the outer air inlet chamber; The seed silicon enters the fluidized bed reactor through the seed crystal feed port, the components and ratio of the process gas are changed, and the process gas drives the seed silicon to react in a fluidized state; 3) After the fluidization inside the fluidized bed reactor becomes stable, the reaction is carried out in the heating area, and the seed silicon grows to become product granular silicon, which is discharged from the outlet of the distributor, and the tail gas after the reaction is discharged through the waste gas outlet of the feed section.

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