A polysilicon dry residue treatment system

Abstract

The utility model provides a kind of polysilicon dry residue processing system, including the feeding unit, sublimator, filtering unit and desublimator connected in turn;Feeding unit includes transfer tank and feeding tank, the transfer tank is equipped with first pressurizing mouth, and feeding tank is equipped with steam inlet, second pressurizing mouth, nitrogen gas boost port and discharge port;Sublimator is equipped with gas phase outlet, nitrogen inlet, waste residue outlet and the feed inlet connected with discharge port;Filtering unit includes cyclone separation and filter, the cyclone separator is equipped with air inlet and dust outlet, the air inlet is connected with gas phase outlet, and dust outlet is connected with feed inlet;Desublimator is the cylinder with cooling jacket, and it is equipped with product outlet, exhaust port and gas phase inlet;It further includes nitrogen source, electric heater and nitrogen pipeline, one end of the nitrogen pipeline is connected with nitrogen source, and the other end is connected to nitrogen gas boost port, nitrogen inlet by electric heater or directly connected to pressurizing mouth;Realize the continuous sublimation and desublimation of aluminium trichloride, and improve recovery efficiency.

Description

Technical Field

[0001] This utility model relates to the field of polysilicon production technology, and in particular to a polysilicon dry slag treatment system. Background Technology

[0002] In the cold hydrogen chemical section of polysilicon production, a slurry is generated whose main components are chlorosilane, silicon powder, metal impurities and aluminum chloride. After the slurry is filtered through the slurry treatment system, a large amount of dry slag containing aluminum trichloride and other components is obtained.

[0003] In traditional production processes, these dried residues are typically treated as solid waste, which not only wastes resources but also poses a risk of environmental pollution. Since aluminum trichloride can directly sublimate from a solid to a gaseous state at high temperatures, this property can be utilized to separate and recover high-purity aluminum trichloride from the residue. However, existing methods often suffer from low recovery efficiency and discontinuous process flows.

[0004] Therefore, it is necessary to propose a polycrystalline silicon dry residue treatment system to solve the above problems. Utility Model Content

[0005] The purpose of this invention is to provide a polycrystalline silicon dry slag treatment system to solve the problems of low recovery efficiency and discontinuous process flow in existing dry slag treatment methods mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A polycrystalline silicon dry residue treatment system includes a feeding unit, a sublimator, a filtration unit and a condenser connected in sequence.

[0008] The feeding unit includes a transfer tank and a feeding tank connected in sequence. The transfer tank is provided with a first pressurization port, and the feeding tank is provided with a steam inlet, a second pressurization port, a nitrogen booster port, and a discharge port.

[0009] The sublimator is provided with a gas phase outlet, a nitrogen inlet, a waste residue outlet, and a feed inlet connected to the discharge port of the feeding tank;

[0010] The filtration unit includes a cyclone separator and a filter connected in sequence. The cyclone separator is provided with an air inlet and a dust outlet. The air inlet is connected to the gas phase outlet, and the dust outlet is connected to the feed inlet of the sublimator.

[0011] The sublimator is a cylindrical body with a cooling jacket, which is provided with a product outlet, an exhaust port and a gas phase inlet connected to the filter;

[0012] It also includes a nitrogen supply unit, which includes a nitrogen source, an electric heater and a nitrogen pipeline. The nitrogen pipeline is connected to the nitrogen source and includes a first pipeline, a second pipeline and a third pipeline. The first pipeline is connected to the first pressurization port and the second pressurization port, respectively. The second pipeline and the third pipeline are connected to the nitrogen booster port and the nitrogen inlet of the sublimator through the electric heater, respectively.

[0013] Preferably, the system further includes an exhaust gas treatment unit, which includes a hydrolysis tank and a scrubbing tower. The hydrolysis tank is connected to the exhaust port of the condenser, and a temperature sensor and a pressure sensor are installed inside the hydrolysis tank. The gas inlet of the scrubbing tower is connected to the outlet of the hydrolysis tank through a venting pipeline, and a regulating valve is installed on the venting pipeline. The regulating valve is controlled and connected to the pressure sensor.

[0014] Preferably, the discharge port of the feeding tank is connected to the inlet of the sublimator via a discharge pipeline, and the outer wall of the discharge pipeline is provided with a heat-insulating and heat-tracing structure.

[0015] Preferably, the medium in the cooling jacket is circulating water and steam.

[0016] Preferably, the sublimator is equipped with a rotating scraper driven by a motor.

[0017] Preferably, the product outlet of the sublimator is connected to a collection tank via a pipe.

[0018] Preferably, the filtration unit further includes a backflush air manifold, which is connected to the filter.

[0019] Preferably, the nitrogen pipeline further includes a fourth pipeline, which is connected to the backflush gas manifold via the electric heater.

[0020] Preferably, the waste outlet of the sublimator is connected to a waste buffer tank via a pipeline.

[0021] Preferably, the filter element is a ceramic filter element.

[0022] Compared with the prior art, the beneficial effects of this utility model are: by using a transfer tank to assist the feeding tank for hot nitrogen-assisted feeding, and then through the continuous operation of equipment such as a sublimator, cyclone separator and filter, continuous feeding of dry residue and continuous sublimation and condensation of aluminum trichloride are achieved, thereby improving processing efficiency and product recovery rate; this system can effectively purify and recover aluminum trichloride in dry residue, realizing resource recycling. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present utility model.

[0025] Figure label:

[0026] 10. Sublimator; 20. Filter unit; 201. Cyclone separator; 202. Filter; 203. Backflush air manifold; 30. Condenser; 40. Transfer tank; 50. Feeding tank; 60. Nitrogen supply unit; 601. Nitrogen source; 602. Electric heater; 603. Nitrogen pipeline; 70. Collection tank; 80. Waste buffer tank. Detailed Implementation

[0027] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this invention. Therefore, the drawings and description are considered exemplary in nature and not restrictive.

[0028] In the description of this utility model, it should be understood that the terms "upper", "lower", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] In this utility model, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0031] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0032] The following disclosure provides many different embodiments or examples for implementing various structures of this invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0033] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0034] like Figure 1As shown, this utility model embodiment provides a polycrystalline silicon dry slag treatment system, including a feeding unit, a sublimator 10, a filtration unit 20, and a condenser 30 connected in sequence; wherein, the feeding unit includes a transfer tank 40 and a feeding tank 50 connected in sequence, the transfer tank 40 is provided with a first pressurization port, and the feeding tank 50 is provided with a steam inlet, a second pressurization port, a nitrogen booster port, and a discharge port; the sublimator 10 is provided with a gas phase outlet, a nitrogen inlet, a waste slag outlet, and a feed inlet connected to the discharge port of the feeding tank 50; the filtration unit 20 includes a cyclone separator 201 and a filter 202 connected in sequence, the cyclone separator 201 is provided with an air inlet and a dust outlet. The air inlet is connected to the gas phase outlet, and the dust outlet is connected to the feed inlet of the sublimator 10. The sublimator 30 is a cylindrical body with a cooling jacket, which is provided with a product outlet, an exhaust outlet and a gas phase inlet connected to the filter 202. It also includes a nitrogen supply unit 60, which includes a nitrogen source 601, an electric heater 602 and a nitrogen pipeline 603. The nitrogen pipeline 603 is connected to the nitrogen source 601 and includes a first pipeline, a second pipeline and a third pipeline. The first pipeline is connected to the first pressurization port and the second pressurization port, respectively. The second pipeline and the third pipeline are connected to the nitrogen booster port and the nitrogen inlet of the sublimator 10 through the electric heater 602, respectively.

[0035] In one embodiment, the filter element of filter 202 is a high-temperature resistant ceramic filter element.

[0036] In operation, the dry slag from the cold hydrogen chemical section is first collected into the transfer tank 40. The transfer tank 40 is then pressurized through the first pressurization port, causing the dry slag to be fed into the feeding tank 50. Saturated steam is then introduced into the feeding tank 50 through the steam inlet to dry the dry slag. Nitrogen gas is then introduced into the feeding tank 50 through the second pressurization port to increase the pressure inside the tank to match the pressure inside the sublimator 10. Hot nitrogen gas is then used to propel the dry slag into the sublimator 10, preventing crystallization of aluminum chloride at low temperatures or condensation of some silanes that could block the pipes. Hot nitrogen is continuously introduced into the nitrogen inlet of the sublimator 10 to heat the dry slag in a high-temperature environment, causing aluminum trichloride to sublimate into a gaseous substance and enter the cyclone separator 201 through the gas phase outlet at the top of the sublimator 10. Some solid particles, diatomaceous earth, silica powder and other substances in the gas phase re-enter the interior of the sublimator 10. After being filtered by the cyclone separator 201 and the filter 202, the gas enters the condenser 30, where the gaseous aluminum trichloride is cooled and crystallized through the cooling jacket to obtain purified aluminum trichloride.

[0037] The hot nitrogen used for the booster and the hot nitrogen introduced into the sublimator 10 are both obtained by heating nitrogen from nitrogen source 601 via electric heater 602. In this embodiment, the nitrogen inlet of the sublimator 10 is located at the bottom of the sublimator 10. The nitrogen is heated to 300°C by electric heater 602 and then introduced into the sublimator 10 to maintain the fluidized state and high temperature inside the sublimator 10.

[0038] The dry residue is continuously fed through the transfer tank 40 and the auxiliary feeding tank 50 with hot nitrogen. Then, through the continuous operation of equipment such as the sublimator 10, cyclone separator 201 and filter 202, the continuous feeding of dry residue and the continuous sublimation and condensation of aluminum trichloride are realized, which improves the processing efficiency and product recovery rate. This system can effectively purify and recover aluminum trichloride in dry residue, realizing the recycling of resources.

[0039] To reduce environmental pollution, an exhaust gas treatment unit is also included. This exhaust gas treatment unit includes a hydrolysis tank and a scrubbing tower. The hydrolysis tank is connected to the exhaust port of the condenser and is equipped with a temperature sensor and a pressure sensor. The gas inlet of the scrubbing tower is connected to the outlet of the hydrolysis tank through a venting pipeline. The venting pipeline is equipped with a regulating valve, which is controlled by the pressure sensor.

[0040] After the gaseous aluminum trichloride crystals are discharged, the remaining gaseous components enter the hydrolysis tank through the exhaust port of the condenser 30. The hydrolysis tank is connected to a water supply line. The harmful substances in the remaining gaseous components undergo hydrolysis and transformation in the hydrolysis tank. When the pressure sensor detects an increase in the pressure inside the tank, it controls the opening of the regulating valve to allow the gas to enter the scrubbing tower for further purification. The gas is then discharged into the atmosphere through the liquid seal tank, effectively avoiding the "smoke" phenomenon caused by the large amount of hydrogen chloride generated during hydrolysis in the existing process, and reducing the impact on the surrounding air quality.

[0041] To further prevent pipe blockage caused by aluminum chloride crystallization or partial silane condensation at low temperatures, the outlet of the feeding tank 50 is connected to the inlet of the sublimator 10 via a discharge pipeline, the outer wall of which is equipped with a heat-insulating and heat-tracing structure.

[0042] Since the gas exiting the cyclone separator 201 still carries a large number of fine solid particles (such as extremely fine silica powder, diatomaceous earth, etc.), these particles will be intercepted by the filter. Over time, a "dust layer" will form on the outer surface of the filter element, making the resistance to gas passage increasingly greater. To address this, the filter unit 20 also includes a backflush air manifold 203, which is connected to the filter 202.

[0043] Specifically, the nitrogen line 603 also includes a fourth line, which is connected to the backflush manifold 203 via an electric heater 602. The backflush manifold 203 cleans the filter element by blowing nitrogen, ensuring that the filter 202 maintains good airflow without interrupting the process flow.

[0044] In order to automatically detach the crystallized aluminum trichloride and ensure the continuity of the system, the sublimator 30 is equipped with a rotating scraper driven by a motor to scrape off the aluminum trichloride that has crystallized onto the inner wall of the sublimator 30.

[0045] In addition, the product outlet of the condenser 30 is connected to a collection tank 70 via a pipeline to collect aluminum trichloride scraped off by the scraper.

[0046] Specifically, the cooling jacket uses circulating water and steam as the medium. The circulating water is used to cool and precipitate aluminum trichloride, and then the scraper is activated to scrape it off and clean it. When there is a lot of crystallization on the inner wall of the condenser 30, making the crystallized aluminum trichloride too hard for the scraper to remove, the circulating water cooling is stopped, and steam is introduced to vaporize the layer of aluminum trichloride near the inner wall of the condenser 30, so that it falls into the collection tank 70.

[0047] Furthermore, the waste outlet of the sublimator 10 is connected to a waste buffer tank 80 via a pipeline. When the continuous reaction rate decreases and the sublimator 10 cools down, the remaining dry waste inside is discharged into the waste buffer tank 80 through the waste outlet at the bottom.

[0048] It should be noted that all equipment is connected by pipelines, and each pipeline is equipped with a control valve.

[0049] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A polycrystalline silicon dry slag treatment system, comprising a feeding unit, a sublimator, a filtration unit, and a condenser connected in sequence, characterized in that: The feeding unit includes a transfer tank and a feeding tank connected in sequence. The transfer tank is provided with a first pressurization port, and the feeding tank is provided with a steam inlet, a second pressurization port, a nitrogen booster port, and a discharge port. The sublimator is provided with a gas phase outlet, a nitrogen inlet, a waste residue outlet, and a feed inlet connected to the discharge port of the feeding tank; The filtration unit includes a cyclone separator and a filter connected in sequence. The cyclone separator is provided with an air inlet and a dust outlet. The air inlet is connected to the gas phase outlet, and the dust outlet is connected to the feed inlet of the sublimator. The sublimator is a cylindrical body with a cooling jacket, which is provided with a product outlet, an exhaust port and a gas phase inlet connected to the filter. It also includes a nitrogen supply unit, which includes a nitrogen source, an electric heater and a nitrogen pipeline. The nitrogen pipeline is connected to the nitrogen source and includes a first pipeline, a second pipeline and a third pipeline. The first pipeline is connected to the first pressurization port and the second pressurization port, respectively. The second pipeline and the third pipeline are connected to the nitrogen booster port and the nitrogen inlet of the sublimator through the electric heater, respectively.

2. The polycrystalline silicon dry slag treatment system according to claim 1, characterized in that, It also includes an exhaust gas treatment unit, which includes a hydrolysis tank and a scrubbing tower. The hydrolysis tank is connected to the exhaust port of the condenser, and a temperature sensor and a pressure sensor are installed inside the hydrolysis tank. The gas inlet of the scrubbing tower is connected to the outlet of the hydrolysis tank through a venting pipeline. A regulating valve is installed on the venting pipeline, and the regulating valve is controlled and connected to the pressure sensor.

3. The polycrystalline silicon dry slag treatment system according to claim 1, characterized in that: The discharge port of the feeding tank is connected to the inlet of the sublimator via a discharge pipeline, and the outer wall of the discharge pipeline is provided with a heat-insulating and heat-tracing structure.

4. The polycrystalline silicon dry slag treatment system according to claim 1, characterized in that: The cooling jacket uses circulating water and steam as its medium.

5. The polycrystalline silicon dry slag treatment system according to claim 1, characterized in that: The sublimator is equipped with a rotating scraper driven by a motor.

6. The polycrystalline silicon dry slag treatment system according to claim 1, characterized in that: The product outlet of the sublimator is connected to a collection tank via a pipeline.

7. The polycrystalline silicon dry slag treatment system according to claim 1, characterized in that: The filtration unit also includes a backflush air manifold, which is connected to the filter.

8. The polycrystalline silicon dry slag treatment system according to claim 7, characterized in that: The nitrogen pipeline also includes a fourth pipeline, which is connected to the backflush gas manifold via the electric heater.

9. The polycrystalline silicon dry slag treatment system according to claim 1, characterized in that: The waste outlet of the sublimator is connected to a waste buffer tank via a pipeline.

10. The polycrystalline silicon dry slag treatment system according to claim 1, characterized in that: The filter element is a ceramic filter element.

Images