Online dumping system for waste silicon powder of trichlorosilane synthetic furnace

Abstract

The utility model discloses an online dumping system for waste silicon powder of a trichlorosilane synthesis furnace, which belongs to the technical field of silicon powder treatment equipment in trichlorosilane synthesis and comprises the trichlorosilane synthesis furnace and a silicon powder collecting tank, a silicon powder discharge port is arranged at the lower part of the trichlorosilane synthesis furnace, and a silicon powder discharge port is arranged at the lower part of the silicon powder collecting tank. The silicon powder discharging port is connected with a feeding port of the silicon powder collecting tank through a pipeline I, the pipeline I is connected with the trichlorosilane synthetic furnace through a socket pipe, a connector connected with the pipeline I and an elbow of the pipeline I adopt ceramic pipe fittings, and a valve I and a valve II are arranged on the pipeline I and close to the trichlorosilane synthetic furnace and the silicon powder collecting tank respectively. And a hydrogen blowing assisting pipeline is also arranged on the pipeline I. The problems that in the prior art, the work load of workers is increased, the maintenance cost is increased, and the equipment yield is influenced due to the fact that silicon powder enriched in the trichlorosilane synthetic furnace needs to be discharged after shutdown are solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of silicon powder processing equipment in trichlorosilane synthesis, and specifically relates to an online backflow system for waste silicon powder of a trichlorosilane synthesis furnace. Background Art

[0002] In the trichlorosilane synthesis stage of the polysilicon production process, the trichlorosilane synthesis furnace that uses cold hydrogenation and discharges silicon powder generally runs continuously for about a week. Due to the enrichment of impurities in the furnace, the temperature in the furnace is extremely difficult to control, and overheating is prone to occur. It is necessary to stop the furnace for maintenance, and then clean the silicon powder in the furnace, restart the furnace to add new silicon powder, and enter the next operation cycle. Stopping the furnace for maintenance will increase the workload of related staff, increase a large amount of maintenance costs, and affect the output of equipment.

[0003] For example, the invention patent application with application number "201210245222.0" and titled "A method and device for recycling waste silicon powder from trichlorosilane synthesis furnace" published on October 24, 2012 proposed a method and device for discharging silicon powder after parking. In this scheme, after the synthesis furnace is normally parked, the synthesis furnace is replaced; after the replacement is qualified, the silicon powder discharge valve at the bottom of the synthesis furnace is connected to the silicon powder collection tank through a metal hose, and nitrogen is introduced into the synthesis furnace through the nitrogen inlet pipeline; the silicon powder discharge valve is opened, and nitrogen is brought into the silicon powder collection tank together with the silicon powder, and the nitrogen is emptied through the bag filter at the top of the silicon powder collection tank, so that the silicon powder is collected in the silicon powder collection tank, realizing the full recovery and use of silicon powder. This is also a commonly used method of inverted silicon powder in the prior art, which will have the aforementioned problems of increasing the workload of relevant staff due to parking for maintenance, increasing a large amount of maintenance costs, and affecting equipment output.

[0004] Therefore, it is necessary to find a better method to export the waste silicon powder in the trichlorosilane synthesis furnace online, extend the operation time of the trichlorosilane synthesis furnace, and at the same time reduce the workload of the staff, reduce maintenance costs, and increase the output of the equipment. Utility Model Content

[0005] The utility model aims to solve the problem in the prior art that the silicon powder enriched in the trichlorosilane synthesis furnace needs to be stopped for discharge, which increases the workload of the staff, increases the maintenance cost and affects the output of the equipment.

[0006] In order to achieve the above-mentioned invention object, the technical solution of the utility model is as follows:

[0007] An online discharge system for waste silicon powder of a trichlorosilane synthesis furnace comprises a trichlorosilane synthesis furnace and a silicon powder collecting tank, wherein a silicon powder discharge port is arranged at the lower part of the trichlorosilane synthesis furnace, the silicon powder discharge port is connected to a feed port of the silicon powder collecting tank through a pipeline I, the pipeline I is connected to the trichlorosilane synthesis furnace by a bell-and-spigot pipe, a joint connected to the pipeline I and an elbow of the pipeline I are provided with ceramic pipe fittings, valves I and II are arranged on the pipeline I near the trichlorosilane synthesis furnace and the silicon powder collecting tank respectively, and a hydrogen blowing-assisting pipeline is also arranged on the pipeline I.

[0008] Furthermore, the straight pipe section on pipeline I is a carbon steel pipe.

[0009] Furthermore, the valve I and valve II are full-diameter valves.

[0010] Furthermore, the valve I and valve II are cut-off valves.

[0011] Furthermore, the hydrogen-assisted blowing pipeline is close to the trichlorosilane synthesis furnace.

[0012] Furthermore, the top of the trichlorosilane synthesis furnace is connected to the filter I through the pipeline II, and the gas outlet I of the filter I is connected to the washing tower, the condenser and the tail gas recovery device in sequence through the pipeline.

[0013] Furthermore, the filter I is a ceramic filter element filter with a filtration accuracy of 1 μm.

[0014] Furthermore, a jacket with a cooling medium is provided outside the silicon powder collection tank, the top outlet of the silicon powder collection tank is connected to the filter II through pipeline III, the gas outlet II of the filter II is connected to the cooler and the tail gas recovery device in turn; the bottom outlet of the silicon powder collection tank is connected to the hydrolysis tank through pipeline IV.

[0015] Furthermore, the filter II is a ceramic filter element filter with a filtration accuracy of 1 μm.

[0016] Furthermore, a cut-off valve I is provided on the hydrogen-assisted blowing pipeline.

[0017] Beneficial effects of the utility model:

[0018] 1. In the utility model, an online reverse discharge system for waste silicon powder from a trichlorosilane synthesis furnace is proposed, whereby the pipeline I between the trichlorosilane synthesis furnace and the silicon powder collection tank is connected by a hard pipe such as a carbon steel pipe, and the elbow of the pipeline I and the joints (such as tees and other joints) connected to the pipeline I are ceramic pipe fittings, which can withstand temperatures up to 350°C and are wear-resistant. At the same time, a bell-and-spigot pipe is used at the connection between the trichlorosilane synthesis furnace and the pipeline I to avoid high-temperature silicon powder from wearing the equipment pipe mouth and the delivery pipeline when discharging silicon powder, and the bell-and-spigot pipe is easy to replace regularly, thereby realizing the online reverse discharge of waste silicon powder from the trichlorosilane synthesis furnace. A hydrogen-assisted blowing pipeline is also provided on the pipeline I to avoid the accumulation of silicon powder in the pipeline during the discharge of silicon powder, so that the discharge of silicon powder is smoother.

[0019] 2. In the utility model, the straight pipe section on pipeline I is a carbon steel pipe. The wear of silicon powder on the straight pipe section is not serious, and the carbon steel pipe can meet the demand.

[0020] 3. In the present invention, the valves I and II are full-diameter valves, which are in a fully open state when discharging silicon powder, and the flow interface is consistent with the inner diameter of the pipeline, thereby avoiding the problem of silicon powder abrading the valves.

[0021] 4. In the present invention, the valves I and II are cut-off valves. If leakage occurs at the connection or on the connecting pipeline between the trichlorosilane synthesis furnace and the silicon powder collection tank, the two cut-off valves can be used to cut off the conveying pipeline in time to ensure the safe online discharge of silicon powder.

[0022] 5. In the present invention, the hydrogen blowing pipeline is close to the trichlorosilane synthesis furnace, and the blowing effect is better.

[0023] 6. In the utility model, the top of the trichlorosilane synthesis furnace is connected to the filter I through the pipeline II, and the gas outlet I of the filter I is connected to the washing tower, the condenser and the tail gas recovery device in sequence through the pipeline. During the silicon powder discharge process, the tail gas discharged from the top of the trichlorosilane synthesis furnace is processed by the filter I, the washing tower and the condenser in sequence, and the non-condensable gas obtained is sent to the tail gas recovery device for recycling.

[0024] 7. In the utility model, a jacket with a cooling medium is provided outside the silicon powder collection tank, and the top outlet of the silicon powder collection tank is connected to the filter II through the pipeline III, and the gas outlet II of the filter II is connected to the cooler and the tail gas recovery device in turn; the bottom outlet of the silicon powder collection tank is connected to the hydrolysis tank through the pipeline IV. The silicon content of the silicon powder discharged into the silicon powder collection tank is less than 10%, and more than 90% are impurities. This silicon powder can basically no longer be used as a raw material. If it is directly discharged and bagged, it is flammable when it encounters air when discharged because of the high impurity content and high activity. Therefore, in this scheme, the silicon powder is first sent to the hydrolysis tank for hydrolysis, and then sent to the sewage treatment system for treatment. The tail gas discharged from the top outlet of the silicon powder collection tank is first filtered by the ceramic filter element of the filter II, and then cooled to room temperature by the cooler. The non-condensable gas is then sent to the tail gas recovery device for recycling. There is no open-loop operation in the whole system, and the tail gas can be recycled. The hydrolysis of waste silicon powder can also reduce the risk of external combustion, and the whole process is safe, reliable and efficient.

[0025] 8. In the present invention, the filter I and filter II are ceramic filter elements with a filtering accuracy of 1 μm, which can intercept most of the silicon powder particles and ensure stable operation of the system.

[0026] 9. In the present invention, a cut-off valve I is provided on the hydrogen-assisted blowing pipeline, and if gas leakage occurs in the system, the hydrogen-assisted blowing can be directly cut off. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the utility model.

[0028] Figure 2 This is a schematic diagram of the structure of pipeline I.

[0029] Figure 3 It is a structural diagram of an implementation method of Example 5.

[0030] Figure 4 It is a structural diagram of an implementation method of Example 3.

[0031] Figure 5 It is a structural diagram of an implementation method of Example 4.

[0032] Figure 6 It is a structural schematic diagram of another preferred implementation method.

[0033] Among them, 1. trichlorosilane synthesis furnace; 2. silicon powder collection tank; 3. pipeline I; 4. joint; 5. valve I; 6. valve II; 7. hydrogen-assisted blowing pipeline; 8. pipeline II; 9. filter I; 10. washing tower; 11. condenser; 12. tail gas recovery device; 13. jacket; 14. pipeline III; 15. filter II; 16. cooler; 17. pipeline IV; 18. hydrolysis tank; 19. shut-off valve I; 20. sewage treatment system; 1.1. silicon powder discharge port; 1.2. cylinder; 2.1. feed port; 2.2. top outlet; 2.3. bottom outlet; 3.1. elbow; 3.2. straight pipe section; 9.1. gas outlet I; 15.1. gas outlet II. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with the embodiments, but the implementation manner of the present invention is not limited thereto.

[0035] Example 1

[0036] An online discharge system for waste silicon powder of a trichlorosilane synthesis furnace belongs to the technical field of silicon powder processing equipment in trichlorosilane synthesis, comprising a trichlorosilane synthesis furnace 1 and a silicon powder collection tank 2, Figure 1 , 2 The lower part of the trichlorosilane synthesis furnace 1 is provided with a silicon powder discharge port 1.1, which is connected to the feed port 2.1 of the silicon powder collecting tank 2 through a pipeline Ⅰ3. The pipeline Ⅰ3 is connected to the trichlorosilane synthesis furnace 1 by a bell-and-spigot pipe. The joint 4 connected to the pipeline Ⅰ3 and the elbow 3.1 of the pipeline Ⅰ3 are made of ceramic pipe fittings. The pipeline Ⅰ3 is respectively provided with a valve Ⅰ5 and a valve Ⅱ6 near the trichlorosilane synthesis furnace 1 and the silicon powder collecting tank 2. A hydrogen blowing pipeline 7 is also provided on the pipeline Ⅰ3.

[0037] The online discharge method of waste silicon powder from trichlorosilane synthesis furnace 1 is as follows:

[0038] When the temperature of trichlorosilane synthesis furnace 1 is getting lower and lower, it means that the content of silicon powder with impurities in trichlorosilane synthesis furnace 1 is too high and needs to be removed from the furnace body. At this time, open valve Ⅰ5 and valve Ⅱ6 without stopping the machine, and blow clean hydrogen through hydrogen-assisted blowing pipeline 7 to ensure that pipeline Ⅰ3 is unobstructed, so as to realize the online backflow of waste silicon powder in trichlorosilane synthesis furnace 1. After the backflow of silicon powder is completed, close valve Ⅰ5 and valve Ⅱ6.

[0039] Preferably, the straight pipe section 3.2 on pipeline I3 is a carbon steel pipe.

[0040] Preferably, the valve I5 and valve II6 are full-bore valves, which are in a fully open state when discharging silicon powder, and the flow interface is consistent with the inner diameter of the pipeline, thereby avoiding the problem of silicon powder wearing the valve.

[0041] Preferably, the valve I5 and valve II6 are cut-off valves. If leakage occurs at the connection or in the connecting pipeline between the trichlorosilane synthesis furnace 1 and the silicon powder collection tank 2, the two cut-off valves can be used to cut off the delivery pipeline in time to ensure the safe online discharge of silicon powder.

[0042] Example 2

[0043] This embodiment is a further optimization of the embodiment 1, the difference being that the hydrogen blowing pipeline 7 is close to the trichlorosilane synthesis furnace 1. Figure 1 Or it can be set between valve Ⅰ5 and valve Ⅱ6. The closer to the trichlorosilane synthesis furnace 1, the better the purging effect.

[0044] Example 3

[0045] Compared with Embodiment 1-2, this embodiment is different in that:

[0046] The top of the trichlorosilane synthesis furnace 1 is connected to a filter Ⅰ9 through a pipeline Ⅱ8, and a gas outlet Ⅰ9.1 of the filter Ⅰ9 is connected to a washing tower 10, a condenser 11 and a tail gas recovery device 12 in sequence through pipelines. Figure 4 .

[0047] Preferably, the filter I9 is ​​a ceramic filter element with a filtration accuracy of 1 μm.

[0048] Example 4

[0049] The difference between this embodiment and embodiments 1-3 is that the silicon powder collecting tank 2 is provided with a jacket 13 through which a cooling medium passes. Figure 5 The top outlet 2.2 of the silicon powder collecting tank 2 is connected to the filter Ⅱ15 through the pipeline Ⅲ14, and the gas outlet Ⅱ15.1 of the filter Ⅱ15 is connected to the cooler 16 and the tail gas recovery device 12 in sequence; the bottom outlet 2.3 of the silicon powder collecting tank 2 is connected to the hydrolysis tank 18 through the pipeline Ⅳ17.

[0050] Preferably, the filter II 15 is a ceramic filter element with a filtration accuracy of 1 μm.

[0051] Example 5

[0052] The difference between this embodiment and embodiment 1-4 is that the hydrogen-assisted blowing pipeline 7 is provided with a cut-off valve I19. Figure 3 .

[0053] Example 6

[0054] To facilitate the public to understand the present solution, this embodiment takes an online discharge system for waste silicon powder from a trichlorosilane synthesis furnace as an example for further explanation.

[0055] refer to Figure 2 ,5 The online inversion system includes a trichlorosilane synthesis furnace 1 and a silicon powder collection tank 2. The lower part of the trichlorosilane synthesis furnace 1 is provided with a silicon powder discharge port 1.1. Specifically, the silicon powder discharge port 1.1 is arranged at the lower part of the cylinder 1.2 of the trichlorosilane synthesis furnace 1 and is located above the nozzle of the trichlorosilane synthesis furnace 1. The silicon powder discharge port 1.1 is connected to the feed port 2.1 of the silicon powder collection tank 2 through a pipeline Ⅰ3. The pipeline Ⅰ3 is connected to the trichlorosilane synthesis furnace 1 by a bell-and-spigot pipe. The joint 4 connected to the pipeline Ⅰ3 (reference Figure 2 Ceramic pipe fittings are used at the three-way joint in the pipeline Ⅰ3 and the elbow 3.1 of the pipeline Ⅰ3. Valve Ⅰ5 and valve Ⅱ6 are respectively provided on the pipeline Ⅰ3 near the trichlorosilane synthesis furnace 1 and the silicon powder collection tank 2. A hydrogen-assisted blowing pipeline 7 is also provided on the pipeline Ⅰ3. A cut-off valve Ⅰ19 is provided on the hydrogen-assisted blowing pipeline 7.

[0056] In this embodiment, the straight pipe section 3.2 on the pipeline I3 is a carbon steel pipeline.

[0057] In this embodiment, the valve I5 and the valve II6 are full-diameter valves, and both the valve I5 and the valve II6 are cut-off valves.

[0058] In this embodiment, the hydrogen blowing pipeline 7 is close to the trichlorosilane synthesis furnace 1.

[0059] In this embodiment, the top of the trichlorosilane synthesis furnace 1 is connected to a filter Ⅰ9 via a pipeline Ⅱ8, and a gas outlet Ⅰ9.1 of the filter Ⅰ9 is connected to a washing tower 10, a condenser 11 and a tail gas recovery device 12 in sequence via pipelines.

[0060] In this embodiment, the filter I9 is ​​a ceramic filter element filter with a filtration accuracy of 1 μm.

[0061] In this embodiment, the silicon powder collection tank 2 is provided with a jacket 13 through which a cooling medium passes, the top outlet 2.2 of the silicon powder collection tank 2 is connected to the filter Ⅱ15 through the pipeline Ⅲ14, and the gas outlet Ⅱ15.1 of the filter Ⅱ15 is connected to the cooler 16 and the exhaust gas recovery device 12 in sequence; the bottom outlet 2.3 of the silicon powder collection tank 2 is connected to the hydrolysis tank 18 through the pipeline Ⅳ17.

[0062] In this embodiment, the filter II 15 is a ceramic filter element with a filtration accuracy of 1 μm.

[0063] When the temperature of trichlorosilane synthesis furnace 1 is getting lower and lower, for example, the temperature is controlled at 320℃ during normal production, there is an exothermic reaction in trichlorosilane synthesis furnace 1, the main reaction is Si+4HCl=SiHCl3+2H2, and the pressure difference of the fluidized bed is controlled to be 20kPa. When the bed pressure difference of trichlorosilane synthesis furnace 1 is gradually increased to 35kPa, the temperature in the furnace is gradually decreasing, indicating that the impurities in the furnace are too enriched, affecting the main reaction, which means that the silicon powder containing a large amount of impurities in the furnace needs to be discharged. The traditional operation method is to take out the silicon powder in the furnace after stopping the machine.

[0064] In this embodiment, there is no need to stop the machine. When the silicon powder in the furnace needs to be discharged, valve I5, valve II6 and cut-off valve I19 are opened, and the impure silicon powder in the trichlorosilane synthesis furnace 1 (the medium reaches 250-300°C and contains hydrogen and chlorosilane) enters pipeline I3 through the bell-and-spigot pipe. The elbow 3.1 in pipeline I3 and the connected joint 4 (such as the connected tee) are parts that are easily eroded by high-temperature silicon powder. Ceramic pipe fittings are used here. Ceramic pipe fittings have the characteristics of high temperature resistance and wear resistance, which can avoid the parts from being worn and pierced, resulting in leakage of chlorosilane and hydrogen. The straight pipe section 3.2 on pipeline I3 is less affected by the erosion force of silicon powder and is not easy to wear. Carbon steel pipes can be used. Pipeline I3 uses bell-and-spigot pipes to connect the trichlorosilane synthesis furnace 1. The bell-and-spigot pipes are replaceable components and can be replaced regularly to ensure the normal and safe operation of the system.

[0065] Valve I5 and valve II6 are both cut-off valves, and are respectively close to trichlorosilane synthesis furnace 1 and silicon powder collection tank 2. When gas leakage or abnormal system operation is detected, pipeline I3 can be cut off in time to ensure that the system operates under safe conditions. A cut-off valve I19 is provided on the hydrogen-assisted blowing pipeline 7, which can also be opened / cut off according to demand.

[0066] After the silicon powder in the trichlorosilane synthesis furnace 1 is discharged, valves Ⅰ5 and Ⅱ6 can be closed. The system can realize online discharge of silicon powder without stopping production, thereby extending the operation time of the trichlorosilane synthesis furnace 1, reducing the workload of the staff, reducing maintenance costs, and increasing the output of the equipment.

[0067] In addition, during the silicon powder discharge process, the tail gas discharged from the top of the trichlorosilane synthesis furnace 1 is processed by the filter Ⅰ9, the washing tower 10, and the condenser 11 in sequence, and the obtained non-condensable gas is sent to the tail gas recovery device 12 for recycling; the silicon powder discharged into the silicon powder collection tank 2 has a silicon content of less than 10%, and more than 90% are impurities. This kind of silicon powder can basically no longer be used as a raw material. If it is directly discharged and bagged, it is flammable when it encounters air when discharged due to the high impurity content and high activity. Therefore, in this scheme, this part of the silicon powder is first sent to the hydrolysis tank 18 for hydrolysis, and then sent to the sewage treatment system 20 for treatment; the tail gas discharged from the top outlet 2.2 of the silicon powder collection tank 2 is first filtered by the ceramic filter element of the filter Ⅱ15, and then cooled to room temperature by the cooler 16. The non-condensable gas is then sent to the tail gas recovery device 12 for recycling. There is no open-loop operation in the whole system, and the tail gas can be recycled. The hydrolysis of waste silicon powder can also reduce the risk of external combustion. The whole process is safe, reliable and efficient.

Claims

1. An online discharge system for waste silicon powder from a trichlorosilane synthesis furnace, characterized in that: The invention comprises a trichlorosilane synthesis furnace (1) and a silicon powder collecting tank (2). The lower part of the trichlorosilane synthesis furnace (1) is provided with a silicon powder discharge port (1.1), the silicon powder discharge port (1.1) is connected to a feed port (2.1) of the silicon powder collecting tank (2) through a pipeline I (3), the pipeline I (3) is connected to the trichlorosilane synthesis furnace (1) by a bell-and-spigot pipe, a joint (4) connected to the pipeline I (3) and an elbow (3.1) of the pipeline I (3) are provided with ceramic pipe fittings, valve I (5) and valve II (6) are provided on the pipeline I (3) near the trichlorosilane synthesis furnace (1) and the silicon powder collecting tank (2), respectively, and a hydrogen blowing pipeline (7) is also provided on the pipeline I (3).

2. The online discharge system for waste silicon powder from a trichlorosilane synthesis furnace according to claim 1, characterized in that: The straight pipe section (3.2) on pipeline I (3) is a carbon steel pipe.

3. The online discharge system for waste silicon powder from a trichlorosilane synthesis furnace according to claim 1, characterized in that: The valve I (5) and valve II (6) are full-diameter valves.

4. The online discharge system for waste silicon powder from a trichlorosilane synthesis furnace according to claim 3 is characterized by: The valve I (5) and valve II (6) are cut-off valves.

5. The online discharge system for waste silicon powder from a trichlorosilane synthesis furnace according to claim 1, characterized in that: The hydrogen-assisted blowing pipeline (7) is close to the trichlorosilane synthesis furnace (1).

6. The online discharge system for waste silicon powder from a trichlorosilane synthesis furnace according to claim 1, characterized in that: The top of the trichlorosilane synthesis furnace (1) is connected to a filter I (9) via a pipeline II (8), and a gas outlet I (9.1) of the filter I (9) is connected in sequence to a washing tower (10), a condenser (11) and a tail gas recovery device (12) via pipelines.

7. The online discharge system for waste silicon powder from a trichlorosilane synthesis furnace according to claim 6, characterized in that: The filter I (9) is a ceramic filter element with a filtration accuracy of 1 μm.

8. The online discharge system for waste silicon powder from a trichlorosilane synthesis furnace according to claim 1, characterized in that: The silicon powder collecting tank (2) is provided with a jacket (13) through which a cooling medium passes. The top outlet (2.2) of the silicon powder collecting tank (2) is connected to a filter (15) via a pipeline (III) (14). The gas outlet (15.1) of the filter (15) is connected to a cooler (16) and an exhaust gas recovery device (12) in sequence. The bottom outlet (2.3) of the silicon powder collecting tank (2) is connected to a hydrolysis tank (18) via a pipeline (IV) (17).

9. The online discharge system for waste silicon powder from a trichlorosilane synthesis furnace according to claim 8, characterized in that: The filter II (15) is a ceramic filter element with a filtration accuracy of 1 μm.

10. The online discharge system for waste silicon powder from a trichlorosilane synthesis furnace according to claim 1, characterized in that: The hydrogen-assisted blowing pipeline (7) is provided with a cut-off valve I (19).

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