A device for treating silicon chloride slurry in a polysilicon production process

Abstract

The utility model discloses a kind of silicon chloride slag slurry processing devices in the production process of polysilicon, it is related to polysilicon production technical field, including settling tank, drying machine, hydrolysis kettle, purification kettle and cleavage reaction kettle, settling tank upper portion outlet is connected with purification kettle import, settling tank bottom outlet is connected with drying machine, purification kettle is connected with cleavage reaction kettle feed port, cleavage reaction kettle is connected with rectification process, the drying machine is connected with rectification process, the liquid phase outlet of the purification kettle, cleavage reaction kettle liquid phase outlet and hydrolysis kettle solid phase outlet are connected with hydrolysis kettle feed port respectively, by solid-liquid separation after sedimentation to slag slurry, clear liquid after precipitation is sent into rectification process for recycling in turn after purification, cleavage, sediment after precipitation is sent into rectification process for recycling after liquid after drying machine steam heating drying, drying solid slag of drying machine, purification residual liquid and cleavage residual liquid are sent to three waste treatments after hydrolysis.

Description

Technical Field

[0001] This utility model relates to the field of polysilicon production technology, and in particular to a device for treating silicon chloride slurry in the polysilicon production process. Background Technology

[0002] Currently, the general treatment of silicon chloride slurry involves settling the collected slurry, discharging the sediment into a hydrolysis reactor, and sending the supernatant to a distillation unit for recovery. The slurry in the bottom of the distillation unit is cooled and settled to remove sediment, while the clear liquid enters a cracking reactor. Under the action of a catalyst and hydrogen chloride, the slurry is cracked to produce silicon tetrachloride and trichlorosilane for chlorosilane recovery.

[0003] Currently, the main problems in the treatment of silicon chloride slurry are as follows:

[0004] 1. Currently, the slurry system is under heavy operating load, pipelines are prone to blockage, the stability of the equipment is poor, the frequency of open-loop operation is high, and the workload of personnel for maintenance and unblocking is heavy.

[0005] 2. During the high-boiling-point cracking reaction, the catalyst is susceptible to poisoning by metallic impurities, resulting in a reaction efficiency of only about 20%.

[0006] 3. Unpyrolyzed polychlorosilanes are hydrolyzed and then enter the downstream sewage treatment and high-salt wastewater treatment systems, increasing the load on the three waste treatment processes.

[0007] 4. The recovery rate of slurry and high-boiling point cannot be effectively improved. Utility Model Content

[0008] This invention aims to provide a device for treating silicon chloride slurry in the polysilicon production process, which can effectively reduce pipeline blockage and effectively remove and purify impurities from the chlorosilane slurry. The process is simple and efficient.

[0009] To achieve the above-mentioned objectives, the technical solution of this utility model is as follows:

[0010] A device for treating silicon chloride slurry in a polysilicon production process includes a settling tank, a dryer, a hydrolysis kettle, a purification kettle, and a pyrolysis reactor. The settling tank is provided with a feed inlet, an upper outlet, and a bottom outlet. The upper outlet is connected to the inlet of the purification kettle, and the bottom outlet is connected to the dryer. The purification kettle is provided with a gas phase outlet I and a liquid phase outlet I, which is connected to the feed inlet of the pyrolysis reactor. The pyrolysis reactor is provided with a gas phase outlet II and a liquid phase outlet II, which is connected to a distillation process. The dryer is provided with a gas phase outlet III and a solid phase outlet, which is connected to the distillation process. The liquid phase outlet I, liquid phase outlet II, and solid phase outlet are respectively connected to the feed inlet of the hydrolysis kettle, and the discharge outlet of the hydrolysis kettle is connected to a waste treatment process.

[0011] Furthermore, the purification vessel is a conventional paddle-type jacketed vessel; the materials are mixed evenly by high-speed stirring of the paddle, achieving a fully mixed state to the greatest extent. By raising the temperature to 180°C, the reaction conditions of the catalyst and metal impurities are triggered to carry out a Lewis acid-base reaction, causing the impurities to precipitate.

[0012] Furthermore, the gas phase outlet I of the purification vessel is equipped with a purification condenser, the inlet of which is connected to the gas phase outlet I, and the outlet of which is connected to a purification collection tank, which is connected to the feed inlet of the pyrolysis reactor.

[0013] The connection pipe between the purification collection tank and the feed inlet of the pyrolysis reactor is equipped with a transfer pump, which transports the material collected in the purification collection tank to the transfer pump.

[0014] Furthermore, the pyrolysis reactor is a conventional paddle-type jacketed reactor; its principle is to introduce the material to be pyrolyzed and the liquid catalyst into the reactor, heat it to 120°C, keep it at that temperature, continuously introduce a certain amount of hydrogen chloride gas, and carry out a gas-liquid two-phase mixing reaction under stirring to produce trichlorosilane and tetrachlorosilane.

[0015] Furthermore, the gas phase outlet II of the pyrolysis reactor is equipped with a pyrolysis condenser, the inlet of which is connected to the gas phase outlet II, and the outlet of which is connected to a pyrolysis receiving tank. The pyrolysis collecting tank is connected to the distillation process.

[0016] Furthermore, the dryer is a horizontal spiral dryer, which heats and dries the liquid in the tank with steam and uses a spiral agitator to stir, which can effectively enhance the stirring intensity and greatly improve the heat exchange effect. The dried gaseous chlorosilane enters the dryer condenser for recovery, and the solid slag is discharged to hydrolysis for treatment.

[0017] Furthermore, the dryer's gas phase outlet III is equipped with a drying condenser, the inlet of which is connected to the dryer's gas phase outlet III, and the outlet of which is connected to a drying receiving tank, which is connected to the distillation process.

[0018] Furthermore, the hydrolysis vessel is a spray-type hydrolysis vessel, which is connected to the absorption tower section through the vessel body head. The absorption tower section is equipped with a spray device. After the gaseous chlorosilanes that are not hydrolyzed in time are fully absorbed by the spray in the tower section, the tail gas enters the tail gas system, and water and hexachlorosilane generate silicon dioxide and other substances, which enter the wastewater treatment.

[0019] The beneficial effects of this utility model are:

[0020] 1. In this utility model, the slurry is separated into solid and liquid phases after sedimentation. The clarified liquid after sedimentation is then purified and pyrolyzed before being sent to a distillation process for recycling. The precipitate after sedimentation is dried by steam heating in a dryer, and the resulting liquid is also sent to a distillation process for recycling. The dried solid residue from the dryer, the purified residue, and the pyrolyzed residue are hydrolyzed and then sent to a waste treatment plant. This method effectively reduces pipeline blockage and utilizes a single reaction vessel with a catalyst to remove impurities and purify the slurry, resulting in a simple and efficient process.

[0021] 2. This invention can increase the recovery rate of chlorosilanes to over 98%, reduce the average hydrolysis amount of chlorosilanes from 5.8 t / day to 0.7 t / day, and save 1683 tons of chlorosilanes annually. High-boiling-point cracking efficiency is improved, with a single-pass conversion rate reaching 90%, and catalyst usage is expected to decrease by 50%. It can also significantly reduce the amount of calcium oxide used as an auxiliary material in wastewater treatment, saving 1277 tons of calcium oxide annually. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the silicon chloride slurry treatment device in the polycrystalline silicon production process of this utility model.

[0023] The components include: 1. Settling tank; 11. Upper outlet; 12. Bottom outlet; 2. Dryer; 21. Gas phase outlet III; 22. Solid phase outlet; 23. Drying condenser; 24. Drying receiving tank; 3. Hydrolysis kettle; 4. Purification kettle; 41. Gas phase outlet I; 42. Liquid phase outlet I; 43. Purification condenser; 44. Purification collection tank; 45. Transfer pump; 5. Cracking reactor; 51. Gas phase outlet II; 52. Liquid phase outlet II; 53. Cracking condenser; 54. Cracking collection tank; 6. Distillation process; 7. Waste treatment process. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0025] Example 1

[0026] This embodiment provides a method such as Figure 1The polysilicon chloride slurry treatment device shown includes a settling tank 1, a dryer 2, a hydrolysis reactor 3, a purification reactor 4, and a pyrolysis reactor 5. The settling tank 1 is provided with a feed inlet, an upper outlet 11, and a bottom outlet 12. The upper outlet 11 is connected to the inlet of the purification reactor 4, and the bottom outlet 12 is connected to the dryer 2. The purification reactor 4 is provided with a gas phase outlet I 41 and a liquid phase outlet I 42. The gas phase outlet I 41 is connected to the feed inlet of the pyrolysis reactor 5. The pyrolysis reactor 5 is provided with a gas phase outlet II 51 and a liquid phase outlet II 52. The gas phase outlet II 51 is connected to the distillation process. The dryer 2 is provided with a gas phase outlet III 21 and a solid phase outlet 22. The gas phase outlet III 21 is connected to the distillation process. The liquid phase outlet I 42, liquid phase outlet II 52, and solid phase outlet 22 are respectively connected to the feed inlet of the hydrolysis reactor 3. The discharge outlet of the hydrolysis reactor 3 is connected to the waste treatment process.

[0027] In this embodiment, the treatment of silicon chloride slurry during the polysilicon production process is completed through the following steps:

[0028] S1. Collect the slurry generated by each device in the polysilicon production process into settling tank 1 for settling;

[0029] S2. The sediment in the settling tank 1 is transported to the dryer 2 through the bottom outlet 12. The drying temperature is controlled in the dryer 2 to separate the chlorosilane from the solid residue. The chlorosilane is transported to the distillation process through the gas phase outlet Ⅲ21 for separation and purification. The solid residue is transported to the hydrolysis kettle 3 through the solid phase outlet 22 for hydrolysis treatment and then transported to the waste treatment process for further treatment.

[0030] S3. The clear liquid after settling in the settling tank 1 is transported to the purification vessel 4 through the upper outlet 11 for purification and impurity removal;

[0031] S4. The purified liquid after purification in purification vessel 4 is transported to pyrolysis reactor 5 through gas phase outlet I41 for catalytic pyrolysis. The purified residue is transported to hydrolysis reactor 3 through liquid phase outlet I42 for hydrolysis treatment and then transported to the waste treatment process for further treatment.

[0032] S5. After the purified liquid undergoes catalytic cracking in the cracking reactor 5, the generated trichlorosilane and silicon tetrachloride are transported to the distillation process through the gas phase outlet II51 for separation and purification. The cracking residue is transported to the hydrolysis reactor 3 through the liquid phase outlet II52 for hydrolysis treatment and then transported to the waste treatment process for further treatment.

[0033] Example 2

[0034] The difference between this embodiment and Embodiment 1 is that, in this embodiment, the purification vessel 4 is a conventional paddle-type jacketed vessel, the gas phase outlet I 41 of the purification vessel 4 is equipped with a purification condenser 43, the inlet of the purification condenser 43 is connected to the gas phase outlet I 41, the outlet of the purification condenser 43 is connected to a purification collection tank 44, the purification collection tank 44 is connected to the feed inlet of the pyrolysis reactor 5, and the connecting pipe between the purification collection tank 44 and the feed inlet of the pyrolysis reactor 5 is equipped with a transfer pump 45; the rest of the structure is the same as in Embodiment 1.

[0035] In this embodiment, the purification vessel 4 is V=7m 3 Paddle-type jacketed reactor; purification condenser 43 with S=50m 2 Shell and tube heat exchanger; the purification collection tank 44 has a capacity of V=7m. 3 The vertical storage tank; the transfer pump 45 is a conventional centrifugal pump.

[0036] In this embodiment, the clarified liquid after settling in the settling tank 1 is transported to the purification vessel 4 through the upper outlet 11 for purification and impurity removal. Inside the purification vessel 4, the materials are mixed uniformly by high-speed stirring with paddles to achieve a fully mixed flow state to the maximum extent. The temperature is raised to 180°C to trigger the reaction conditions between the catalyst and the metallic impurities, resulting in a Lewis acid-base reaction that precipitates the impurities. The purified liquid obtained after purification is in a gaseous state at high temperature. The mixed gas phase of hexachlorodisilane, hexachlorooxysilane, and silicon tetrachloride is discharged through the gas phase outlet I 41, condensed by the purification condenser 43, and then enters the purification collection tank 44. The material collected in the purification collection tank 44 is transported to the transfer pump 45. The purified residue obtained after purification is a mixture of catalyst and polychlorinated silanes; it is transported to the hydrolysis vessel 3 through the liquid phase outlet I 42 for hydrolysis treatment and then sent to the waste treatment process for further treatment.

[0037] Example 3

[0038] The difference between this embodiment and Embodiment 1 is that, in this embodiment, the pyrolysis reactor 5 is a conventional paddle-type jacketed reactor. The gas phase outlet II 51 of the pyrolysis reactor 5 is equipped with a pyrolysis condenser 53, the inlet of which is connected to the gas phase outlet II 51, and the outlet of which is connected to a pyrolysis receiving tank. The pyrolysis collection tank 54 is connected to the distillation process. The remaining structure is the same as in Embodiment 1.

[0039] In this embodiment, the pyrolysis reactor 5 has a volume of V=7m. 3 Conventional paddle-type jacketed reactor; the pyrolysis condenser 53 has an S=50m 2 The shell-and-tube heat exchanger, wherein the pyrolysis collection tank 54 has a V=7m³. 3 Vertical storage tanks.

[0040] In this embodiment, the purified solution undergoes catalytic cracking in a cracking reactor. Utilizing the alkaline nature of the catalyst and the acidic nature of the metal chloride, a Lewis acid-base reaction is carried out to achieve complexation. The generated trichlorosilane and silicon tetrachloride are transported to the distillation process through the gas phase outlet II51 for separation and purification. The cracking residue, a mixture of catalyst and polychlorinated silanes, is transported to the hydrolysis reactor 3 through the liquid phase outlet II52 for hydrolysis treatment and then sent to the waste treatment process for further processing.

[0041] Example 4

[0042] The difference between this embodiment and Embodiment 1 is that, in this embodiment, the dryer 2 is a horizontal spiral dryer 2; a drying condenser 23 is provided at the gas phase outlet III 21 of the dryer 2, the inlet of the drying condenser 23 is connected to the gas phase outlet III 21 of the dryer 2, and a drying receiving tank 24 is connected to the outlet of the drying condenser 23, which is connected to the distillation process. The rest of the structure is the same as in Embodiment 1.

[0043] In this embodiment, the dryer 2 has a capacity of V=4m. 3 It is a horizontal spiral dryer; the dryer condenser 23 has an S=45m. 2 Shell and tube heat exchanger; the drying receiving tank 24 has a V=2m 3 Vertical storage tanks;

[0044] In this embodiment, the precipitate in settling tank 1 is conveyed to dryer 2 through bottom outlet 12, where it is evaporated and dried by steam heating at a controlled temperature of 120°C. The low-boiling-point chlorosilanes are evaporated, and the remaining high-boiling-point polychlorinated silanes and solid residue are subjected to hydrolysis. Solid residue and chlorosilanes are separated in dryer 2. The drying temperature in dryer 2 is 120°C. Chlorosilanes and polychlorinated silanes have different boiling points; chlorosilanes have a boiling point below 100°C, while polychlorinated silanes have a boiling point above 145°C. Therefore, the gas separated in dryer 2 is chlorosilane. The chlorosilane is conveyed to the distillation process for separation and purification through gas phase outlet Ⅲ21, while the solid residue is conveyed to the hydrolysis reactor 3 through solid phase outlet 22 for hydrolysis treatment, and then to the waste treatment process for further treatment.

[0045] Example 5

[0046] The difference between this embodiment and embodiment 1 is that in this embodiment, the hydrolysis vessel 3 is a spray-type hydrolysis vessel, while the rest of the structure is the same as in embodiment 1.

[0047] In this embodiment, the hydrolysis vessel 3 has a vessel volume (V) of 15m. 3 Spray-type hydrolysis reactor.

[0048] In this embodiment, the hydrolysis vessel 3 hydrolyzes the dried solid residue, purified residue and pyrolysis residue of the dryer 2 and sends them to the waste treatment plant. The residue is pretreated by taking advantage of the reaction between high-boiling-point polychlorinated silanes and water and the easy solubility of the catalyst in water. The high-boiling-point polychlorinated silanes are hydrolyzed to generate silicon dioxide and then sent to the wastewater treatment plant.

[0049] It is understood that this utility model has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this utility model. Furthermore, under the teachings of this utility model, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of this utility model.

Claims

1. A device for treating silicon chloride sludge in a polysilicon production process, characterized by: The reactor includes a settling tank (1), a dryer (2), a hydrolysis vessel (3), a purification vessel (4), and a pyrolysis reactor (5). The settling tank (1) is provided with a feed inlet, an upper outlet (11), and a bottom outlet (12). The upper outlet (11) is connected to the inlet of the purification vessel (4), and the bottom outlet (12) is connected to the dryer (2). The purification vessel (4) is provided with a gas phase outlet I (41) and a liquid phase outlet I (42). The gas phase outlet I (41) is connected to the feed inlet of the pyrolysis reactor (5). The pyrolysis reactor (5) is equipped with a gas phase outlet II (51) and a liquid phase outlet II (52). The gas phase outlet II (51) is connected to the distillation process. The dryer (2) is equipped with a gas phase outlet III (21) and a solid phase outlet (22). The gas phase outlet III (21) is connected to the distillation process. The liquid phase outlet I (42), liquid phase outlet II (52) and solid phase outlet (22) are respectively connected to the feed inlet of the hydrolysis reactor (3). The discharge outlet of the hydrolysis reactor (3) is connected to the waste treatment process.

2. The apparatus for treating silicon chloride slurry in a polysilicon production process according to claim 1, wherein: The purification vessel (4) is a conventional paddle-type jacketed vessel.

3. The apparatus for treating silicon chloride slurry in the polysilicon production process according to claim 2, wherein: The purification vessel (4) has a purification condenser (43) installed at the gas phase outlet I (41). The inlet of the purification condenser (43) is connected to the gas phase outlet I (41), and the outlet of the purification condenser (43) is connected to a purification collection tank (44). The purification collection tank (44) is connected to the feed inlet of the pyrolysis reactor (5).

4. The apparatus for treating silicon chloride slurry in the polysilicon production process according to claim 3, wherein: The connection pipe between the purification collection tank (44) and the feed inlet of the pyrolysis reactor (5) is equipped with a transfer pump (45), through which the material collected in the purification collection tank (44) is transported to the transfer pump (45).

5. The apparatus for treating silicon chloride slurry in the polysilicon production process according to claim 1, wherein: The pyrolysis reactor (5) is a conventional paddle-type jacketed reactor.

6. The apparatus for treating silicon chloride slurry in the polysilicon production process according to claim 5, wherein: The gas phase outlet II (51) of the pyrolysis reactor (5) is equipped with a pyrolysis condenser (53). The inlet of the pyrolysis condenser (53) is connected to the gas phase outlet II (51). The outlet of the pyrolysis condenser (53) is connected to a pyrolysis receiving tank. The pyrolysis collection tank (54) is connected to the distillation process.

7. The apparatus for treating silicon chloride slurry in the polysilicon production process according to claim 1, wherein: The dryer (2) is a horizontal spiral dryer (2).

8. The apparatus for treating silicon chloride slurry in the polysilicon production process according to claim 7, wherein: The dryer (2) is equipped with a drying condenser (23) at the gas phase outlet Ⅲ (21). The inlet of the drying condenser (23) is connected to the gas phase outlet Ⅲ (21) of the dryer (2). The outlet of the drying condenser (23) is connected to a drying receiving tank (24). The drying receiving tank (24) is connected to the distillation process.

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