Cold hydrogenated nitrogen recovery system

Abstract

The utility model discloses a cold hydrogenated nitrogen recovery system which is characterized in that nitrogen of a cold hydrogenated silicon powder conveying unit and nitrogen replaced after system maintenance are recovered to a nitrogen storage tank, the nitrogen enters a nitrogen drying device through the top of the nitrogen storage tank, after being dried, the nitrogen enters a nitrogen compressor, and low-pressure nitrogen is compressed and then fed into a high-pressure nitrogen storage tank; in the whole process, nitrogen flow is powered by a compressor. The compressed nitrogen can be used for pressurizing a storage tank of residual liquid generated by replacement of cold hydrogenation equipment, conveying the residual liquid to a downstream slag slurry treatment device through pressure difference, replacing cold hydrogenation material-containing equipment before overhaul, and replacing materials before overhaul of a cold hydrogenation fluidized bed system, so that the nitrogen waste is reduced, and the energy consumption is reduced. The comprehensive production cost is reduced.

Description

Technical Field

[0001] The utility model belongs to the field of polysilicon production, and in particular relates to a cold hydrogenated nitrogen recovery system. Background Art

[0002] In the hydrogenation process for polysilicon production, the silicon powder required as raw material for the fluidized bed reactor is transported from the silicon powder silo to the silicon powder low-pressure tank using nitrogen. When the silicon powder high-pressure tank is empty, the silicon powder is replenished from the low-pressure tank to the high-pressure tank.

[0003] After the silicon powder is transported from the silicon powder silo to the silicon powder low-pressure tank by nitrogen, the nitrogen required for transportation flows from the top of the silicon powder low-pressure tank to the low-pressure dust collector, and is discharged into the atmosphere after dust removal by the low-pressure dust collector; since the pressure of the silicon powder high-pressure tank is controlled by the hydrogen pressure, the silicon powder low-pressure tank is connected to the silicon powder low-pressure tank. In order to prevent the hydrogen in the silicon powder high-pressure tank from flowing into the silicon powder low-pressure tank, the silicon powder low-pressure tank is often protected by nitrogen. The protective nitrogen flows from the top of the silicon powder low-pressure tank to the low-pressure dust collector, and is discharged into the atmosphere after dust removal by the low-pressure dust collector.

[0004] The cold hydrogenation fluidized bed system needs to be shut down for maintenance periodically. After the maintenance is completed, nitrogen must be used to replace the fluid to the dew point and the micro-oxygen level must be qualified before the system can be used to start up with materials. The replacement nitrogen used after the system maintenance is completed is discharged into the atmosphere, resulting in a large amount of nitrogen waste. Summary of the Invention

[0005] Purpose of the utility model: The technical problem to be solved by the utility model is to provide a cold hydrogenated nitrogen recovery system to address the deficiencies of the existing technology, to recover nitrogen from the cold hydrogenated silicon powder conveying unit and to replace nitrogen after the system maintenance is completed, thereby reducing nitrogen waste and lowering the overall production cost.

[0006] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0007] A cold hydrogenation nitrogen recovery system comprises a nitrogen dust removal device, a nitrogen recovery tank, a nitrogen compressor and a nitrogen collection tank; the nitrogen dust removal device feed port is connected to the top gas outlet of a low-pressure silicon powder tank, the nitrogen dust removal device exhaust port is connected to the nitrogen recovery tank via a pipeline, and the nitrogen dust removal device bottom discharge port is returned to the low-pressure silicon powder tank via a feed pipe; the nitrogen recovery tank, the nitrogen compressor and the nitrogen collection tank are connected in sequence via pipelines.

[0008] Specifically, the nitrogen dust removal device includes a low-pressure dust collector and a nitrogen compressor inlet dust collector; the low-pressure dust collector feed port is connected to the low-pressure silicon powder tank outlet, the exhaust port is connected to the nitrogen compressor inlet dust collector through a pipeline, and the bottom discharge port is connected to the low-pressure silicon powder tank through a discharge pipe; the top gas outlet of the nitrogen compressor inlet dust collector is connected to the nitrogen recovery tank through a pipeline.

[0009] Furthermore, the air inlet of the nitrogen compressor inlet dust collector is also connected to the cold hydrogenation system maintenance venting device, and the nitrogen vented during maintenance is sent to the nitrogen compressor inlet dust collector for dust removal and recovery.

[0010] Furthermore, a nitrogen drying device is provided on the pipeline between the nitrogen recovery tank and the nitrogen compressor.

[0011] Furthermore, a nitrogen compressor air intake buffer tank is provided on the pipeline between the nitrogen drying device and the nitrogen compressor.

[0012] Furthermore, a nitrogen compressor exhaust buffer tank is provided on the pipeline between the nitrogen compressor and the nitrogen collection tank.

[0013] Furthermore, the rear end of the nitrogen collection tank is connected to the residual liquid tank through an outlet pipe, and the recovered nitrogen is used as the punching gas of the residual liquid tank. The pressure difference is used to send the residual liquid returned to the residual liquid tank before system maintenance to the slurry processing device.

[0014] Furthermore, the rear end of the nitrogen collection tank is connected to a replacement nitrogen replenishing device for shutdown and maintenance of the cold hydrogenation system through an outlet pipe, and the recovered nitrogen is sent into the cold hydrogenation system through the replacement nitrogen replenishing device as replacement nitrogen during system maintenance.

[0015] Furthermore, the rear end of the nitrogen collection tank is connected to the replacement nitrogen equipment for maintenance of each material-containing moving equipment in the cold hydrogenation system through an outlet pipe, and the recovered nitrogen is sent into each material-containing moving equipment through the replacement nitrogen equipment as replacement nitrogen during maintenance.

[0016] Furthermore, the exhaust pipe of the low-pressure dust collector is connected to the vent pipe of the cold hydrogenation system maintenance vent device and then connected to the nitrogen compressor inlet dust collector. Beneficial effects

[0017] This new cold hydrogenation nitrogen recovery system recycles nitrogen from the cold hydrogenated silicon powder delivery unit and nitrogen replacement after system maintenance into a nitrogen storage tank. The nitrogen then flows through the top of the nitrogen storage tank into a nitrogen drying unit. After drying, the nitrogen enters a nitrogen compressor, where the low-pressure nitrogen is compressed and then delivered to a high-pressure nitrogen storage tank. The compressor powers the nitrogen flow throughout this process. The compressed nitrogen can be used to pressurize the residual liquid storage tank generated by the replacement of cold hydrogenation equipment, transporting the residual liquid to downstream slurry processing equipment via a pressure differential. It can also be used to replace materials in cold hydrogenation fluidized bed systems prior to maintenance.

[0018] This system recycles nitrogen from the cold hydrogenated silicon powder conveying unit and replaces nitrogen after system maintenance, and reuses it after drying, reducing nitrogen waste and lowering overall production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more apparent.

[0020] Figure 1 It is a schematic diagram of the overall structure of the cold hydrogenation nitrogen recovery system.

[0021] Wherein, each reference numeral represents:

[0022] 1-Low-pressure silicon powder tank; 2-High-pressure silicon powder tank; 3-Low-pressure dust collector; 4-Nitrogen compressor inlet dust collector; 5-Nitrogen recovery tank; 6-Nitrogen drying device; 7-Nitrogen compressor inlet buffer tank; 8-Nitrogen compressor; 9-Nitrogen compressor exhaust buffer tank; 10-Nitrogen collection tank; 11-Residual liquid tank; 12-Fluidized bed reactor; 13-Cold hydrogenation system maintenance venting device; 14-Displacement nitrogen replenishing device; 15-Displacement nitrogen equipment; 16-Residual liquid; 17-Slurry treatment device; 18-Tail gas treatment device. DETAILED DESCRIPTION

[0023] The present invention can be better understood according to the following embodiments.

[0024] The structures, proportions, sizes, etc. illustrated in the drawings of the specification are only used to match the contents disclosed in the specification for the understanding and reading of those familiar with this technology. They are not used to limit the conditions for the implementation of the utility model and therefore have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed in the utility model without affecting the efficacy and purpose of the utility model. At the same time, terms such as "upper", "lower", "front", "back", and "middle" quoted in this specification are only for the convenience of description and are not used to limit the scope of the implementation of the utility model. Changes or adjustments in their relative relationships should also be considered as the scope of the implementation of the utility model without substantially changing the technical content.

[0025] Combine Figure 1 As shown, the cold hydrogenation nitrogen recovery system of the present invention includes a nitrogen dust removal device, a nitrogen recovery tank 5, a nitrogen compressor 8 and a nitrogen collection tank 10; the feed port of the nitrogen dust removal device is connected to the top air outlet of the low-pressure silicon powder tank 1, the exhaust port of the nitrogen dust removal device is connected to the nitrogen recovery tank 5 through a pipeline, and the bottom discharge port of the nitrogen dust removal device is connected to the low-pressure silicon powder tank 1 through a discharge pipe to return the collected fine powder to the low-pressure silicon powder tank 1; the nitrogen recovery tank 5, the nitrogen compressor 8 and the nitrogen collection tank 10 are connected in sequence by pipelines.

[0026] In some embodiments, the nitrogen dust removal device includes a low-pressure dust collector 3 and a nitrogen compressor inlet dust collector 4; the feed port of the low-pressure dust collector 3 is connected to the gas outlet of the low-pressure silicon powder tank 1, the exhaust port is connected to the nitrogen compressor inlet dust collector 4 through a pipe, and the bottom discharge port is connected to the low-pressure silicon powder tank 1 through a discharge pipe; the top gas outlet of the nitrogen compressor inlet dust collector 4 is connected to the nitrogen recovery tank 5 through a pipe.

[0027] In some embodiments, the air inlet of the nitrogen compressor inlet dust collector 4 is also connected to the cold hydrogenation system maintenance venting device 13, and the nitrogen vented during maintenance is sent to the nitrogen compressor inlet dust collector 4 for dust removal and recovery.

[0028] In some embodiments, a nitrogen drying device 6 is further provided on the pipeline between the nitrogen recovery tank 5 and the nitrogen compressor 8 .

[0029] In some embodiments, a nitrogen compressor air inlet buffer tank 7 is further provided on the pipeline between the nitrogen drying device 6 and the nitrogen compressor 8 .

[0030] In some embodiments, a nitrogen compressor exhaust buffer tank 9 is further provided on the pipeline between the nitrogen compressor 8 and the nitrogen collection tank 10 .

[0031] In some embodiments, the rear end of the nitrogen collection tank 10 is connected to the residual liquid tank 11 through an outlet pipe, and the recovered nitrogen is used as the punching gas of the residual liquid tank 11. The pressure difference is used to send the residual liquid 16 returned to the residual liquid tank 11 before system maintenance to the slurry processing device 17.

[0032] In some embodiments, the rear end of the nitrogen collection tank 10 is connected to the replacement nitrogen replenishing device 14 for the shutdown and maintenance of the cold hydrogenation system through an outlet pipe, and the recovered nitrogen is sent into the cold hydrogenation system through the replacement nitrogen replenishing device 14 as replacement nitrogen during system maintenance.

[0033] In some embodiments, the rear end of the nitrogen collection tank 10 is connected to the replacement nitrogen equipment 15 for maintenance of each material-containing moving equipment in the cold hydrogenation system through an outlet pipe, and the recovered nitrogen is sent into each material-containing moving equipment through the replacement nitrogen equipment 15 as replacement nitrogen during maintenance.

[0034] In some embodiments, the exhaust pipe of the low-pressure dust collector 3 is connected to the vent pipe of the cold hydrogenation system maintenance vent device 13 and then connected to the nitrogen compressor inlet dust collector 4.

[0035] During use, the low-pressure silicon powder tank 1 is connected to the nitrogen gas source 101 and the silicon powder silo 102 through a pipeline, and silicon powder raw materials and protective nitrogen are added to the low-pressure silicon powder tank 1. When the silicon powder sent to the fluidized bed reactor 12 by the high-pressure silicon powder tank 2 is used up, silicon powder needs to be replenished from the low-pressure silicon powder tank 1. After the silicon powder in the low-pressure silicon powder tank 1 is replenished to the high-pressure silicon powder tank 2, the silicon powder is pneumatically transported from the silicon powder silo 101 to the low-pressure silicon powder tank 1 for standby use by the high-pressure silicon powder tank 2. The nitrogen used by the low-pressure silicon powder tank 1 to transport the silicon powder is mixed with the protective nitrogen of the low-pressure silicon powder tank 1 and enters the low-pressure dust collector 3 to remove the silicon powder entrained in the nitrogen. The nitrogen at the outlet of the low-pressure dust collector 3 is mixed with the nitrogen vented by the cold hydrogenation system maintenance venting device 13 and enters the nitrogen compressor inlet dust collector 4. After another dust removal, the nitrogen at the outlet of the nitrogen compressor inlet dust collector 4 enters the nitrogen recovery tank 5 and passes through the nitrogen. The nitrogen from the drying device 6 enters the nitrogen compressor intake buffer tank 7 and is compressed by the nitrogen compressor 8 before entering the nitrogen compressor exhaust buffer tank 9. The compressed high-pressure nitrogen enters the nitrogen collecting tank 10. The nitrogen in the nitrogen collecting tank 10 is used on the one hand to replace materials before the system is shut down for maintenance and to replace equipment containing materials before maintenance; on the other hand, the residual liquid returned to the residual liquid tank 11 before equipment maintenance can be pressurized with this nitrogen, and the pressure difference can be used to send the residual liquid in the residual liquid tank 11 to the slurry treatment device 17. Finally, the replaced nitrogen enters the tail gas treatment device 18 for treatment and then discharged after passing the treatment.

[0036] This utility model provides a concept and method for a cold hydrogenation nitrogen recovery system. There are many methods and approaches to implement this technical solution. The above is only a preferred embodiment of the utility model. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the utility model, and such improvements and modifications should also be considered within the scope of protection of the utility model. Any components not specified in this embodiment may be implemented using existing technologies.

Claims

1. A cold hydrogenation nitrogen recovery system, characterized in that: The invention comprises a nitrogen dust removal device, a nitrogen recovery tank (5), a nitrogen compressor (8) and a nitrogen collection tank (10); the feed port of the nitrogen dust removal device is connected to the top air outlet of the low-pressure silicon powder tank (1), the exhaust port of the nitrogen dust removal device is connected to the nitrogen recovery tank (5) through a pipeline, and the bottom discharge port of the nitrogen dust removal device is returned to the low-pressure silicon powder tank (1) through a feed pipe; the nitrogen recovery tank (5), the nitrogen compressor (8) and the nitrogen collection tank (10) are connected in sequence through pipelines.

2. The cold hydrogenated nitrogen recovery system according to claim 1, characterized in that: The nitrogen dust removal device comprises a low-pressure dust collector (3) and a nitrogen compressor inlet dust collector (4); the feed port of the low-pressure dust collector (3) is connected to the gas outlet of the low-pressure silicon powder tank (1), the exhaust port is connected to the nitrogen compressor inlet dust collector (4) through a pipeline, and the bottom discharge port is connected to the low-pressure silicon powder tank (1) through a feed pipe; the top gas outlet of the nitrogen compressor inlet dust collector (4) is connected to the nitrogen recovery tank (5) through a pipeline.

3. The cold hydrogenated nitrogen recovery system according to claim 2, characterized in that: The air inlet of the nitrogen compressor inlet dust collector (4) is also connected to the cold hydrogenation system maintenance venting device (13), and the nitrogen vented during maintenance is sent to the nitrogen compressor inlet dust collector (4) for dust removal and recovery.

4. The cold hydrogenated nitrogen recovery system according to claim 1, characterized in that: A nitrogen drying device (6) is also provided on the pipeline between the nitrogen recovery tank (5) and the nitrogen compressor (8).

5. The cold hydrogenated nitrogen recovery system according to claim 4, characterized in that: A nitrogen compressor air inlet buffer tank (7) is also provided on the pipeline between the nitrogen drying device (6) and the nitrogen compressor (8).

6. The cold hydrogenated nitrogen recovery system according to claim 1, characterized in that: A nitrogen compressor exhaust buffer tank (9) is also provided on the pipeline between the nitrogen compressor (8) and the nitrogen collection tank (10).

7. The cold hydrogenated nitrogen recovery system according to claim 1, characterized in that: The rear end of the nitrogen collecting tank (10) is connected to the residual liquid tank (11) through an outlet pipe, and the recovered nitrogen is used as the punching gas of the residual liquid tank (11). The residual liquid (16) returned to the residual liquid tank (11) before system maintenance is sent to the slurry processing device (17) by utilizing the pressure difference.

8. The cold hydrogenated nitrogen recovery system according to claim 1, characterized in that: The rear end of the nitrogen collecting tank (10) is connected to a replacement nitrogen replenishing device (14) for shutdown and maintenance of the cold hydrogenation system through an outlet pipe, and the recovered nitrogen is sent into the cold hydrogenation system through the replacement nitrogen replenishing device (14) as replacement nitrogen during system maintenance.

9. The cold hydrogenated nitrogen recovery system according to claim 1, characterized in that: The rear end of the nitrogen collecting tank (10) is connected to the replacement nitrogen equipment (15) for maintenance of each material-containing moving equipment in the cold hydrogenation system through an outlet pipe, and the recovered nitrogen is sent to each material-containing moving equipment through the replacement nitrogen equipment (15) as replacement nitrogen during maintenance.

10. The cold hydrogenated nitrogen recovery system according to claim 3, characterized in that: The exhaust pipe of the low-pressure dust collector (3) is connected to the vent pipe of the cold hydrogenation system maintenance vent device (13) and then connected to the nitrogen compressor inlet dust collector (4).

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