Silicon powder recovery system

Abstract

The utility model relates to the field of polycrystalline silicon, in particular to a silicon powder recovery system. The silicon powder recovery system comprises a dust removal unit; the first silicon powder collecting tank is connected with the dust removal unit; a feeding hole of the first storage tank is connected with a discharging hole of the first silicon powder collecting tank; a first material inlet of the waste contact body tank is connected with a first material outlet of the first storage tank; the first replacement pipeline is communicated with the bottom of the first storage tank, and the first replacement pipeline is configured to introduce replacement gas into the first storage tank; a second storage tank; and the exhaust pipeline is connected between the first storage tank and the second storage tank. The replacement gas can be introduced into the first storage tank through the first replacement pipeline, so that the content of chlorosilane in the first storage tank is reduced, the replaced chlorosilane gas is discharged into the second storage tank through the exhaust pipeline, and liquid accumulation in the waste contact tank caused by chlorosilane liquid is avoided.

Description

Technical Field

[0001] This application relates to the field of polysilicon, and particularly to a silicon powder recovery system. Background Art

[0002] In the polysilicon industry, trichlorosilane is produced through the cold hydrogenation process. The main reaction of cold hydrogenation is: Si + 2H2 + 3SiCl4 → 4SiHCl3. Silicon powder, hydrogen, and silicon tetrachloride react in a fluidized bed. The mixed gas after the reaction (molar ratio: H2: 63.25%, STC (silicon tetrachloride, SiCl4): 26.5%; TCS (trichlorosilane, SiHCl3): 10.25%) is mixed with silicon powder. The mixed gas first passes through a dust removal unit for dust removal, then through a scrubbing tower to remove metal chlorides, and finally through a cooling system to cool the chlorosilane to a chlorosilane storage tank.

[0003] The dust removal unit regularly discharges silicon powder into a silicon powder collection tank. The silicon powder in the silicon powder collection tank is then discharged into a first storage tank, and the silicon powder in the first storage tank is finally discharged into a waste contact body tank. During the process of the dust removal unit discharging silicon powder into the silicon powder collection tank, gaseous chlorosilane (including STC and TCS) will enter the interior of the silicon powder collection tank. Nitrogen is used to displace hydrogen and chlorosilane in the waste contact body tank, and after displacement, silicon powder is discharged from the bottom of the waste contact body tank into a ton bag for recycling.

[0004] However, during the process of the dust removal unit discharging silicon powder into the silicon powder collection tank, the first storage tank, and the waste contact body tank, the temperature continuously drops, resulting in the continuous condensation of chlorosilane into a liquid state, and finally being discharged into the waste contact body tank, causing blockage at the bottom of the waste contact body tank. It is difficult to completely displace the liquid-phase chlorosilane even by consuming a large amount of nitrogen in the waste contact body tank. If the discharged silicon powder carries liquid, it may cause harm to the staff, and the silicon powder cannot be reused, resulting in an increase in the production cost of polysilicon. Summary of the Utility Model

[0005] Based on this, this application provides a silicon powder recovery system to solve the problem that the interior of the waste contact body tank is prone to liquid accumulation in the related art.

[0006] The silicon powder recovery system provided by this application includes:

[0007] A dust removal unit;

[0008] A first silicon powder collection tank, which is connected to the dust removal unit;

[0009] A first storage tank, the feed port of which is connected to the discharge port of the first silicon powder collection tank;

[0010] A waste contact body tank, the first feed port of which is connected to the first discharge port of the first storage tank;

[0011] The first replacement pipeline is connected to the bottom of the first storage tank and is configured to introduce replacement gas into the first storage tank;

[0012] The second storage tank;

[0013] The exhaust pipeline is connected between the first storage tank and the second storage tank.

[0014] In a possible implementation, the dust removal unit includes a cyclone separator and a silicon powder filter. The first discharge port of the cyclone separator is connected to the first silicon powder collection tank, and the second discharge port of the cyclone separator is connected to the feed port of the silicon powder filter;

[0015] The silicon powder recovery system further includes a second silicon powder collection tank. The feed port of the second silicon powder collection tank is connected to the first discharge port of the silicon powder filter, and the second silicon powder collection tank is connected to the second feed port of the waste catalyst body tank.

[0016] In a possible implementation, the silicon powder recovery system further includes a second replacement pipeline that is connected to the bottom of the second silicon powder collection tank and is configured to introduce replacement gas into the second silicon powder collection tank; the first silicon powder collection tank and the second silicon powder collection tank are respectively connected to the second storage tank through the exhaust pipeline.

[0017] In a possible implementation, the silicon powder recovery system further includes a first pressure relief pipeline that is connected to the first storage tank.

[0018] In a possible implementation, the silicon powder recovery system further includes a second pressure relief pipeline that is connected to the second silicon powder collection tank.

[0019] In a possible implementation, the silicon powder recovery system further includes a scrubbing tower that is connected to the second discharge port of the silicon powder filter.

[0020] In a possible implementation, the second storage tank is a slurry buffer tank, and the slurry buffer tank is connected to the first discharge port of the scrubbing tower.

[0021] In a possible implementation, the exhaust pipeline includes a main path, a first branch, and a second branch. The main path is connected to the slurry buffer tank, the first branch is connected to the first storage tank, and the second branch is connected to the second silicon powder collection tank. One end of the first branch away from the first storage tank and one end of the second branch away from the second silicon powder collection tank are respectively connected to one end of the main path away from the slurry buffer tank.

[0022] In a possible implementation, first on-off valves are respectively installed on the first branch and the second branch.

[0023] In a possible implementation, the exhaust pipeline further includes a slurry treatment branch, which is connected to one end of the main pipeline far from the slurry buffer tank, and a second switching valve is installed on the slurry treatment branch.

[0024] The present application provides a silicon powder recovery system, which includes a dust removal unit, a first silicon powder collection tank, a first storage tank, a waste catalyst body tank, a first displacement pipeline, a second storage tank, and an exhaust pipeline. The dust removal unit can filter the mixed gas discharged from the filtration fluidized bed. The silicon powder filtered by the dust removal unit can be discharged to the first silicon powder collection tank, and the silicon powder in the first silicon powder collection tank can be discharged to the first storage tank. After the silicon powder and chlorosilane in the first silicon powder collection tank enter the first storage tank, a displacement gas can be introduced into the first storage tank through the first displacement pipeline, where the displacement gas can be hot hydrogen, so that the content of chlorosilane in the first storage tank is reduced, and the heat of the displacement gas can prevent the chlorosilane gas from condensing. The displaced chlorosilane gas is discharged to the second storage tank through the exhaust pipeline. After the gas in the first storage tank is displaced, the silicon powder in the first storage tank can be discharged into the waste catalyst body tank to avoid liquid accumulation in the waste catalyst body tank caused by chlorosilane liquid. Nitrogen can be used to displace hydrogen in the waste catalyst body tank, which is beneficial to reducing the nitrogen displacement usage and lowering the production cost of polysilicon. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 It is a schematic structural diagram of the silicon powder recovery system provided by the embodiment of the present application.

[0027] Description of the Reference Numerals:

[0028] 100, dust removal unit; 110, cyclone separator; 120, silicon powder filter;

[0029] 200, first silicon powder collection tank;

[0030] 300, first storage tank; 310, first displacement pipeline; 320, first pressure relief pipeline;

[0031] 400, waste catalyst body tank;

[0032] 500, second storage tank;

[0033] 600, second silicon powder collection tank; 610, second displacement pipeline; 620, second pressure relief pipeline;

[0034] 700, exhaust pipeline; 710, main path; 720, first branch; 730, second branch; 740, slurry treatment branch; 750, first on-off valve; 760, second on-off valve;

[0035] 800, scrubber; 810, circulation pump. Detailed implementation manners

[0036] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the preferred embodiments of the present application. In the drawings, the same or similar reference numerals denote the same or similar components or components with the same or similar functions from beginning to end. The described embodiments are some, but not all, of the embodiments of the present application. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application and should not be construed as a limitation to the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts fall within the scope of protection of the present application. The embodiments of the present application will be described in detail below with reference to the drawings.

[0037] In the description of the present application, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, or an indirect connection through an intermediate medium, or the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0038] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is the orientation or positional relationship based on the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0039] The terms "first", "second", "third" (if any) in the description and claims of the present application and the above drawings are used to distinguish similar objects and do not have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0040] In addition, the terms "comprising", "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or display comprising a series of steps or units need not be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or displays.

[0041] In the prior art, the dust removal unit regularly discharges silicon powder into the silicon powder collection tank, the silicon powder in the silicon powder collection tank is then discharged into the first storage tank, and the silicon powder in the first storage tank is finally discharged into the waste contact body tank. During the process of the dust removal unit discharging silicon powder into the silicon powder collection tank, gaseous chlorosilanes (including STC and TCS) will enter the interior of the silicon powder collection tank. Nitrogen is used to displace hydrogen and chlorosilanes in the waste contact body tank, and after displacement, silicon powder is discharged from the bottom of the waste contact body tank for recycling in a ton bag. However, during the process of the dust removal unit discharging silicon powder into the silicon powder collection tank, the first storage tank and the waste contact body tank, the temperature continuously drops, resulting in continuous condensation of chlorosilanes into liquid state, and finally discharged into the waste contact body tank, causing blockage at the bottom of the waste contact body tank. It is difficult to completely displace the liquid-phase chlorosilanes even with a large amount of nitrogen consumed in the waste contact body tank. If the discharged silicon powder carries liquid, it may cause harm to the staff, and the silicon powder cannot be reused, resulting in an increase in the production cost of polysilicon.

[0042] After repeated thinking and verification, the inventor found that by connecting a first displacement pipeline to the first storage tank, after the silicon powder and chlorosilane gas in the first silicon powder collection tank are discharged into the first storage tank, the first displacement pipeline can introduce hot displacement gas such as hot hydrogen into the first storage tank, and displace the chlorosilane gas in the first storage tank through the displacement gas, so that the content of chlorosilane gas in the first storage tank is reduced. Furthermore, after the temperature in the first storage tank drops, the phenomenon of liquefaction of chlorosilane gas will not occur in the first storage tank. The chlorosilane gas displaced from the first storage tank can be discharged into the second storage tank. After the chlorosilane gas in the first storage tank is displaced, the silicon powder in the first storage tank can be discharged into the waste contact body tank, avoiding the accumulation of liquid in the waste contact body tank caused by chlorosilane liquid. Nitrogen can be used to displace hydrogen in the waste contact body tank, which is beneficial to reducing the usage amount of nitrogen displacement and lowering the production cost of polysilicon.

[0043] In view of this, the inventor designed a silicon powder recovery system. A first displacement pipeline is connected to the first storage tank. The first displacement pipeline can introduce displacement gas into the first storage tank, and the first storage tank is connected to the second storage tank through an exhaust pipeline. The gas introduced by the first displacement pipeline can prevent the liquefaction of chlorosilane gas in the first storage tank. After the first storage tank discharges silicon powder into the waste contact body tank, the content of chlorosilane in the waste contact body tank is reduced, avoiding the accumulation of liquid in the waste contact body tank, and avoiding harm to the staff caused by chlorosilane liquid while ensuring that the silicon powder discharged from the waste contact body tank can be reused.

[0044] The technical solution of the silicon powder recovery system provided by the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0045] Referring to Figure 1 As shown, the silicon powder recovery system provided by the embodiments of the present application includes a dust removal unit 100, a first silicon powder collection tank 200, a first storage tank 300, a waste catalyst tank 400, a first replacement pipeline 310, a second storage tank 500, and an exhaust pipeline 700. The first silicon powder collection tank 200 is connected to the dust removal unit 100. The feed port of the first storage tank 300 is connected to the discharge port of the first silicon powder collection tank 200. The first feed port of the waste catalyst tank 400 is connected to the first discharge port of the first storage tank 300. The first replacement pipeline 310 communicates with the bottom of the first storage tank 300, and the first replacement pipeline 310 is configured to introduce replacement gas into the first storage tank 300. The exhaust pipeline 700 is connected between the first storage tank 300 and the second storage tank 500.

[0046] Among them, the dust removal unit 100 can filter out larger particles of silicon powder in the mixed gas discharged from the fluidized bed, and the filtered silicon powder and part of the chlorosilane gas enter the first silicon powder collection tank 200. Schematically, the temperature of the mixed gas entering the dust removal unit 100 is about 230 °C, and the pressure is about 2.6 Mpa. Under this operating condition, the chlorosilane is in a gaseous phase. Optionally, the substance entering the first silicon powder collection tank 200 from the dust removal unit 100 contains 36.75% of chlorosilane.

[0047] The first silicon powder collection tank 200 can act as a high-pressure tank, and the first storage tank 300 can act as a low-pressure tank. After the first silicon powder collection tank 200 discharges silicon powder to the first storage tank 300, the pressure of the mixed gas drops to about 0.7 MPa. At this time, the gas expands and does external work, and the temperature drops slightly, and the temperature is still about 200 °C. The first storage tank 300 can buffer the pressure of the mixed gas and reduce the wear of the pipeline caused by the silicon powder in the mixed gas.

[0048] The specific type of the replacement gas in this embodiment is not limited. For example, hot hydrogen can be used as the replacement gas. In the polysilicon field, hot hydrogen is relatively easy to obtain, which is beneficial to reducing the cost of the silicon powder recovery system. Optionally, a switching valve can be installed on the first replacement pipeline 310. After the silicon powder in the first silicon powder collection tank 200 is discharged into the first storage tank 300, the staff can open the switching valve on the first replacement pipeline 310 to replace the chlorosilane in the first storage tank 300. It is worth mentioning that the density of hot hydrogen is lower than that of chlorosilane. Connecting the first replacement pipeline 310 to the bottom of the first storage tank 300 is beneficial to reliably replacing the chlorosilane in the first storage tank 300. The chlorosilane in the first storage tank 300 can be discharged from the first storage tank 300 into the second storage tank 500. Through replacement, the content of chlorosilane in the first storage tank 300 is reduced. After the temperature in the first storage tank 300 drops to room temperature, there will be no liquefaction of chlorosilane in the first storage tank 300.

[0049] After replacing the gas in the first storage tank 300, the gas and silicon powder in the first storage tank 300 can enter the inside of the waste catalyst body tank 400, and there will be no liquid accumulation in the waste catalyst body tank 400. Compared with the prior art of using nitrogen to replace the chlorosilane liquid in the waste catalyst body tank 400, when using nitrogen to replace the gas in the waste catalyst body tank 400, the number of nitrogen replacements can be reduced, effectively saving nitrogen.

[0050] For the silicon powder recovery system provided in this embodiment, its dust removal unit 100 can filter the mixed gas discharged from the filter fluidized bed. The silicon powder filtered out by the dust removal unit 100 can be discharged to the first silicon powder collection tank 200, and the silicon powder in the first silicon powder collection tank 200 can be discharged to the first storage tank 300. After the silicon powder and chlorosilane in the first silicon powder collection tank 200 enter the first storage tank 300, a replacement gas can be introduced into the first storage tank 300 through the first replacement pipeline 310. The replacement gas can be hot hydrogen, so that the content of chlorosilane in the first storage tank 300 is reduced, and the heat of the replacement gas can prevent the chlorosilane gas from condensing. The replaced chlorosilane gas is discharged into the second storage tank 500 through the exhaust pipeline 700. After the gas in the first storage tank 300 is replaced, the silicon powder in the first storage tank 300 can be discharged into the waste catalyst body tank 400 to avoid liquid accumulation in the waste catalyst body tank 400 caused by chlorosilane liquid. Nitrogen can be used to replace hydrogen in the waste catalyst body tank 400, which is beneficial to reducing the usage amount of nitrogen replacement and lowering the production cost of polysilicon.

[0051] In one embodiment, as Figure 1As shown, the dust removal unit 100 includes a cyclone separator 110 and a silicon powder filter 120. The first discharge port of the cyclone separator 110 is connected to the first silicon powder collection tank 200, and the second discharge port of the cyclone separator 110 is connected to the feed port of the silicon powder filter 120.

[0052] The silicon powder recovery system further includes a second silicon powder collection tank 600. The feed port of the second silicon powder collection tank 600 is connected to the first discharge port of the silicon powder filter 120, and the second silicon powder collection tank 600 is connected to the second feed port of the waste catalyst body tank 400.

[0053] Among them, the mixed gas discharged from the fluidized bed first enters the cyclone separator 110 to separate out larger particles of silicon powder. After being separated by the cyclone separator 110, it enters the silicon powder filter 120 for filtration to filter out smaller particles of silicon powder. The silicon powder and part of the mixed gas separated by the cyclone separator 110 enter the first silicon powder collection tank 200, and the silicon powder and part of the mixed gas filtered by the silicon powder filter 120 enter the second silicon powder collection tank 600.

[0054] It is worth mentioning that part of the silicon powder can be stored in the silicon powder filter 120, and the second silicon powder collection tank 600 can also act as a low-pressure tank. The silicon powder in the first storage tank 300 and the second silicon powder collection tank 600 can be discharged into the waste catalyst body tank 400 respectively.

[0055] With this structure, the dust removal unit 100 separates the mixed gas discharged from the fluidized bed twice, thereby effectively separating the silicon powder in the mixed gas discharged from the fluidized bed, enabling more silicon powder to be recycled and helping to reduce the production cost of polysilicon.

[0056] In a specific embodiment, as Figure 1 shown, the silicon powder recovery system further includes a second replacement pipeline 610. The second replacement pipeline 610 is communicated with the bottom of the second silicon powder collection tank 600, and the second replacement pipeline 610 is configured to introduce replacement gas into the second silicon powder collection tank 600. The first silicon powder collection tank 200 and the second silicon powder collection tank 600 are respectively connected to the second storage tank 500 through an exhaust pipeline 700.

[0057] Among them, the replacement gas introduced into the second silicon powder collection tank 600 by the second replacement pipeline 610 and the replacement gas introduced into the first storage tank 300 by the first replacement pipeline 310 can be the same or different, and no unique limitation is made here. Exemplarily, the second replacement pipeline 610 can introduce hot hydrogen into the second silicon powder collection tank 600.

[0058] Optionally, a switching valve is installed on the second replacement pipeline 610. After the silicon powder in the silicon powder filter 120 is discharged into the second silicon powder collection tank 600, the staff can open the switching valve on the second replacement pipeline 610 to replace the chlorosilane in the second silicon powder collection tank 600. The second replacement pipeline 610 is connected to the bottom of the second silicon powder collection tank 600, which is conducive to reliably replacing the chlorosilane in the second silicon powder collection tank 600, and the heat of the replacement gas provided by the second replacement pipeline 610 can also prevent the chlorosilane in the second silicon powder collection tank 600 from liquefying.

[0059] In this embodiment, the chlorosilane in the first storage tank 300 is replaced by the replacement gas introduced through the first replacement pipeline 310, and the chlorosilane in the second silicon powder collection tank 600 is replaced by the replacement gas introduced through the second replacement pipeline 610, further avoiding liquid accumulation in the waste contact body tank 400, thereby further reducing the production cost of polysilicon.

[0060] In a specific embodiment, as Figure 1 shown, the silicon powder recovery system further includes a first pressure relief pipeline 320, and the first pressure relief pipeline 320 is connected to the first storage tank 300.

[0061] Schematically, the first pressure relief pipeline 320 can be connected to the top of the first storage tank 300. A switching valve can be provided on the first pressure relief pipeline 320, and the staff can control the pressure relief of the first storage tank 300 by controlling the state of the switching valve on the first pressure relief pipeline 320. Optionally, the gas discharged from the first pressure relief pipeline 320 can be recovered after being filtered by a filter.

[0062] By providing the first pressure relief pipeline 320, a certain pressure difference can be ensured between the first silicon powder collection tank 200 and the first storage tank 300, ensuring that the gas and silicon powder in the first silicon powder collection tank 200 can reliably enter the first storage tank 300.

[0063] In a specific embodiment, as Figure 1 shown, the silicon powder recovery system further includes a second pressure relief pipeline 620, and the second pressure relief pipeline 620 is connected to the second silicon powder collection tank 600.

[0064] Schematically, the second pressure relief pipeline 620 can be connected to the top of the second silicon powder collection tank 600. A switching valve can be provided on the second pressure relief pipeline 620, and the staff can control the pressure relief of the second silicon powder collection tank 600 by controlling the state of the switching valve on the second pressure relief pipeline 620. Optionally, the gas discharged from the second pressure relief pipeline 620 can be recovered after being filtered by a filter.

[0065] By providing the second pressure relief pipeline 620, a certain pressure difference can be ensured between the silicon powder filter 120 and the second silicon powder collection tank 600, guaranteeing that the gas and silicon powder in the silicon powder filter 120 can reliably enter the second silicon powder collection tank 600.

[0066] Figure 1 As shown, the silicon powder recovery system further includes a scrubbing tower 800, which is connected to the second discharge port of the silicon powder filter 120.

[0067] Among them, the silicon powder contains impurities, which form metal chlorides after the cold hydro - chlorination process. The mixed gas discharged from the fluidized bed enters the scrubbing tower 800 after dust removal by the dust removal unit 100. The scrubbing tower 800 can remove the metal chlorides and finer silicon powder particles in the mixed gas. As Figure 1 shown, the scrubbing tower 800 is connected with a circulation pump 810, which can drive the liquid to flow in the scrubbing tower 800.

[0068] By providing the scrubbing tower 800, the impurities in the mixed gas discharged from the fluidized bed can be further removed, facilitating the recovery of the mixed gas discharged from the fluidized bed and reducing the production cost of polysilicon.

[0069] Optionally, the second storage tank 500 is a slurry buffer tank, which is connected to the first discharge port of the scrubbing tower 800.

[0070] It can be understood that the slurry buffer tank can not only store the gas displaced from the first storage tank 300 and the gas displaced from the second silicon powder collection tank 600, but also store the slag discharged from the scrubbing tower 800.

[0071] In this structure, the gas displaced from the first storage tank 300 and the second silicon powder collection tank 600 can make the slag in the slurry buffer tank mix fully with the liquid, preventing the slag in the slurry buffer tank from accumulating and blocking the pipeline at the bottom of the slurry buffer tank.

[0072] In other embodiments, an air vent pipeline can be connected to the bottom of the slurry buffer tank, through which air can be introduced into the slurry buffer tank to make the slag in the slurry buffer tank mix fully with the liquid.

[0073] In a possible implementation, as Figure 1 shown, the exhaust pipeline 700 includes a main path 710, a first branch 720 and a second branch 730. The main path 710 is connected to the slurry buffer tank, the first branch 720 is connected to the first storage tank 300, and the second branch 730 is connected to the second silicon powder collection tank 600. The end of the first branch 720 away from the first storage tank 300 and the end of the second branch 730 away from the second silicon powder collection tank 600 are respectively connected to the end of the main path 710 away from the slurry buffer tank.

[0074] Specifically, the gas displaced from the first storage tank 300 can enter the interior of the slurry buffer tank via the first branch 720 and the main path 710, and the gas displaced from the second silicon powder collection tank 600 can enter the interior of the slurry buffer tank via the second branch 730 and the main path 710. Exemplarily, the first branch 720 and the second branch 730 can be respectively connected to the main path 710 through a tee joint.

[0075] This structure is beneficial to reducing the number of pipelines in the silicon powder recovery system and facilitating the reduction of the space occupied by the silicon powder recovery system.

[0076] Figure 1 It is shown that first shut-off valves 750 are respectively installed on the first branch 720 and the second branch 730.

[0077] It can be understood that the first shut-off valve 750 on the first branch 720 can control the connection state of the first branch 720, and the first shut-off valve 750 on the second branch 730 can control the connection state of the second branch 730. The specific structure of the first shut-off valve 750 in this embodiment is not limited, and those skilled in the art can set it according to actual needs.

[0078] By respectively setting first shut-off valves 750 on the first branch 720 and the second branch 730 to control the connection states of the corresponding branches, those skilled in the art can control the gas in the first storage tank 300 and / or the second silicon powder collection tank 600 to be displaced into the interior of the slurry buffer tank as needed, which is beneficial to improving the versatility of the silicon powder recovery system.

[0079] In a possible implementation manner, as Figure 1 shown, the exhaust pipeline 700 further includes a slurry treatment branch 740, the slurry treatment branch 740 is connected to one end of the main path 710 far from the slurry buffer tank, and a second shut-off valve 760 is installed on the slurry treatment branch 740.

[0080] Among them, the slurry in the slurry buffer tank can be regularly discharged to the slurry section via the main path 710 and the slurry treatment branch 740. Specifically, when displacing the gas in the first storage tank 300 and the second silicon powder collection tank 600, the first shut-off valve 750 on the first branch pipe and the first shut-off valve 750 on the second branch pipe are opened, and the second shut-off valve 760 on the slurry treatment branch 740 is closed. When the slurry buffer tank discharges the slag material, the first shut-off valve 750 on the first branch pipe and the first shut-off valve 750 on the second branch pipe are closed, and the second shut-off valve 760 on the slurry treatment branch 740 is opened.

[0081] Through the above settings, the chlorosilane in the first storage tank 300 and the second silicon powder collection tank 600, as well as the slag and liquid washed out by the washing tower 800, can be sent to the slag slurry section for recovery and treatment through the main path 710 and the slag slurry treatment branch 740, reducing the production cost of polysilicon while avoiding environmental pollution.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A silicon powder recovery system, characterized in that: include: Dust removal unit (100); A first silicon powder collection tank (200), wherein the first silicon powder collection tank (200) is connected to the dust removal unit (100); A first storage tank (300), wherein a feed port of the first storage tank (300) is connected to a discharge port of the first silicon powder collecting tank (200); A waste contact tank (400), wherein a first feed port of the waste contact tank (400) is connected to a first discharge port of the first storage tank (300); a first replacement pipeline (310), the first replacement pipeline (310) being in communication with the bottom of the first storage tank (300), and the first replacement pipeline (310) being configured to pass replacement gas into the first storage tank (300); A second storage tank (500); An exhaust pipeline (700), wherein the exhaust pipeline (700) is connected between the first storage tank (300) and the second storage tank (500).

2. The silicon powder recovery system according to claim 1, characterized in that: The dust removal unit (100) comprises a cyclone separator (110) and a silicon powder filter (120), wherein a first discharge port of the cyclone separator (110) is connected to the first silicon powder collection tank (200), and a second discharge port of the cyclone separator (110) is connected to a feed port of the silicon powder filter (120); The silicon powder recovery system further comprises a second silicon powder collecting tank (600), the feed port of the second silicon powder collecting tank (600) being connected to the first discharge port of the silicon powder filter (120), and the second silicon powder collecting tank (600) being connected to the second feed port of the waste contact tank (400).

3. The silicon powder recovery system according to claim 2, characterized in that: The silicon powder recovery system further comprises a second replacement pipeline (610), wherein the second replacement pipeline (610) is connected to the bottom of the second silicon powder collection tank (600), and the second replacement pipeline (610) is configured to pass replacement gas into the second silicon powder collection tank (600); the first silicon powder collection tank (200) and the second silicon powder collection tank (600) are respectively connected to the second storage tank (500) via the exhaust pipeline (700).

4. The silicon powder recovery system according to claim 2, characterized in that: The silicon powder recovery system further comprises a first pressure relief pipeline (320), wherein the first pressure relief pipeline (320) is connected to the first storage tank (300).

5. The silicon powder recovery system according to claim 2, characterized in that: The silicon powder recovery system further comprises a second pressure relief pipeline (620), wherein the second pressure relief pipeline (620) is connected to the second silicon powder collection tank (600).

6. The silicon powder recovery system according to claim 3, characterized in that: The silicon powder recovery system further comprises a washing tower (800), and the washing tower (800) is connected to the second discharge port of the silicon powder filter (120).

7. The silicon powder recovery system according to claim 6, characterized in that: The second storage tank (500) is a slurry buffer tank, and the slurry buffer tank is connected to the first discharge port of the washing tower (800).

8. The silicon powder recovery system according to claim 7, characterized in that: The exhaust pipeline (700) comprises a main route (710), a first branch route (720) and a second branch route (730); the main route (710) is connected to the slurry buffer tank, the first branch route (720) is connected to the first storage tank (300), and the second branch route (730) is connected to the second silicon powder collecting tank (600); an end of the first branch route (720) away from the first storage tank (300) and an end of the second branch route (730) away from the second silicon powder collecting tank (600) are respectively connected to an end of the main route (710) away from the slurry buffer tank.

9. The silicon powder recovery system according to claim 8, characterized in that: The first branch (720) and the second branch (730) are respectively installed with a first switch valve (750).

10. The silicon powder recovery system according to claim 8, characterized in that: The exhaust pipeline (700) further comprises a slurry processing branch (740), wherein the slurry processing branch (740) is connected to an end of the main line (710) away from the slurry buffer tank, and a second switch valve (760) is installed on the slurry processing branch (740).

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