Polycrystalline silicon cold hydrogenation process treatment system and treatment method

Abstract

The invention relates to the technical field of polycrystalline silicon production, and provides a polycrystalline silicon cold hydrogenation process treatment system and a treatment method. The treatment system comprises a quench tower, a heat exchanger, a flushing pipe and a slurry collecting and treating module. Wherein a tower kettle residue discharge port of the quench tower is connected with a residue discharge pipe, the other end of the residue discharge pipe is connected with the heat exchanger, the heat exchanger is used for heating and dissolving high-boiling residues discharged by the quench tower, and a residue discharge outlet of the heat exchanger is connected with the slurry collection and treatment module. The outlet end of the flushing pipe is connected to the residue discharging pipe, and the flushing pipe can be used for injecting flushing media into the residue discharging pipe to flush the residue discharging pipe. Through the arrangement of the flushing pipe and the heat exchanger, the high-boiling-point substances in the residues are further dissolved in the flushing medium, so that the content of the high-boiling-point substances in the residue discharging outlet of the heat exchanger is reduced, the blocking risk in a connecting pipeline of the residue discharging outlet of the heat exchanger and the residue slurry collecting and processing module is further reduced, and the system safety is improved.

Description

Technical Field

[0001] The present application relates to the technical field of polysilicon production, and in particular to a polysilicon cold hydrogenation process treatment system and treatment method. Background Art

[0002] Polysilicon is an important industrial material, widely used in the photovoltaic industry and the electronics industry, and is used as one of the key materials for manufacturing semiconductor devices and solar cells.

[0003] The existing polysilicon production generally uses metallurgical silicon and hydrogen chloride to synthesize trichlorosilane gas, which is easy to purify. The trichlorosilane gas is then distilled and purified, and finally the high-purity trichlorosilane gas is converted into high-purity polysilicon through reduction reaction and chemical vapor deposition. However, in the process of reducing trichlorosilane to polysilicon, a large amount of highly toxic byproduct silicon tetrachloride is produced. Therefore, the recovery and utilization of silicon tetrachloride has become a key factor restricting the production of polysilicon.

[0004] In the prior art, the byproduct silicon tetrachloride in the reduction process is usually treated by a cold hydrogenation process. However, the chlorosilane and hydrogen mixed gas coming out of the fluidized bed hydrogenation reactor usually contains high-boiling chlorosilanes, metal chlorides and a trace amount of fine silicon powder. After being sprayed and cooled and washed in the quench tower, the remaining fine silicon powder, high-boiling chlorosilanes and metal chlorides gradually crystallize and precipitate in the quench tower kettle, which can easily lead to blockage of the quench tower residual discharge pipeline and blockage in the slurry collection and treatment module in the subsequent process. Summary of the invention

[0005] The present application provides a polysilicon cold hydrogenation process treatment system and treatment method to solve the blockage problem that may occur in the quench tower residual discharge pipe and the slurry collection and treatment module.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions:

[0007] The first aspect of the present application provides a polysilicon cold hydrogenation process treatment system for treating the reaction products of a cold hydrogenation reactor, and the treatment system includes: a quenching tower, a bottom discharge port of the quenching tower is connected to a discharge pipe; a heat exchanger, connected to the other end of the discharge pipe, and used for heating and dissolving high-boiling substances discharged from the quenching tower; a flushing pipe, the outlet end of which is connected to the discharge pipe, and the flushing pipe is used to inject a flushing medium into the discharge pipe to flush the discharge pipe; and a slurry collection and treatment module, which is connected to the discharge outlet of the heat exchanger.

[0008] As an optional implementation, the flushing pipe is connected to the silicon tetrachloride storage via a delivery pump; the silicon tetrachloride storage is at least used to store silicon tetrachloride produced in the polysilicon synthesis reactor.

[0009] As an optional embodiment, it further includes: a vaporizer, which is used to transport the reaction gas to the cold hydrogenation reactor; the heat exchanger also includes a gas outlet, which is connected to the vaporizer.

[0010] As an optional implementation, the quenching tower is further provided with a spray liquid inlet, and the spray liquid inlet is connected to the silicon tetrachloride storage tank.

[0011] As an optional implementation, the slurry collection and processing module includes a slurry collection tank, a filter, and a slurry processing device which are sequentially connected to the exhaust outlet of the heat exchanger.

[0012] As an optional implementation, at least two slurry collecting tanks and at least two filters are provided, and the slurry collecting tanks and the filters are provided in a one-to-one correspondence.

[0013] As an optional implementation, the quenching tower is provided with a tower top exhaust port, and the tower top exhaust port is connected to the circulating hydrogen storage tank, the silicon tetrachloride storage tank and the polysilicon reduction reactor.

[0014] As an optional implementation, the polysilicon cold hydrogenation process treatment system further includes a cyclone separator and a silicon powder filter; the cold hydrogenation reactor is connected to the cyclone separator, the silicon powder filter and the quenching tower in sequence.

[0015] The second aspect of the present application provides a polysilicon cold hydrogenation process treatment method, which is applied to any of the polysilicon cold hydrogenation process treatment systems mentioned above, and the treatment method includes: cooling and washing the mixed gas generated after the reaction of the cold hydrogenation reactor through a quenching tower; using the flushing medium flowing out of the flushing pipe to flush the residue in the exhaust pipe of the quenching tower, and the residue flows into the heat exchanger with the flushing medium; heating and dissolving the residue through the heat exchanger; and processing the residue discharged from the heat exchanger through a slurry collection and processing module.

[0016] As an optional embodiment, the flushing medium flowing out of the flushing pipe is silicon tetrachloride, and the treatment method also includes: recovering the silicon tetrachloride gas vaporized in the heat exchanger, and sending the recovered silicon tetrachloride gas to a cold hydrogenation reactor to participate in a cold hydrogenation reaction.

[0017] As an optional embodiment, the processing method also includes: recovering the mixed gas discharged from the top exhaust port of the quenching tower; condensing the mixed gas to separate hydrogen, silicon tetrachloride and trichlorosilane; transporting the hydrogen to a circulating hydrogen storage device to participate in a cold hydrogenation reaction again; distilling and purifying silicon tetrachloride and trichlorosilane, and transporting the separated silicon tetrachloride to a silicon tetrachloride storage device to participate in a cold hydrogenation reaction again, and transporting trichlorosilane to a polysilicon reduction reactor to participate in a reduction reaction.

[0018] The polysilicon cold hydrogenation process treatment system and treatment method provided in the present application are used to treat the reaction products of the cold hydrogenation reactor. The treatment system includes: a quenching tower, a heat exchanger, a flushing pipe, and a slurry collection and treatment module. Among them, the tower kettle discharge port of the quenching tower is connected to a discharge pipe, and the other end of the discharge pipe is connected to the heat exchanger. The heat exchanger is used to heat and dissolve the high-boiling substances discharged from the quenching tower, and the discharge outlet of the heat exchanger is connected to the slurry collection and treatment module. The outlet end of the flushing pipe is connected to the discharge pipe, and the flushing pipe is used to inject a flushing medium into the discharge pipe to flush the discharge pipe.

[0019] By introducing a flushing pipe connected to the residual discharge pipe and injecting a flushing medium into the residual discharge pipe to flush the residue in the residual discharge pipe, it is possible to prevent residual silicon powder, high-boiling chlorosilane and metal chloride crystals from clogging the pipe and reducing safety hazards. At the same time, the residue will flow into the heat exchanger along with the flushing medium, and the heat exchanger can heat and dissolve the high-boiling substances discharged from the quenching tower, so that the high-boiling substances in the residue are further dissolved in the flushing medium. Thus, the high-boiling substance content in the residual discharge outlet of the heat exchanger is reduced, and the risk of blockage in the connecting pipe between the residual discharge outlet of the heat exchanger and the slurry collection and treatment module is further reduced, thereby improving the safety of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A schematic diagram of the structure of a polysilicon cold hydrogenation process treatment system provided in an embodiment of the present application;

[0022] Figure 2 A schematic diagram of the structure of another polysilicon cold hydrogenation process system provided in an embodiment of the present application;

[0023] Figure 3 A schematic diagram of the structure of a polysilicon preparation system provided in an embodiment of the present application;

[0024] Figure 4 A schematic flow chart of a polysilicon cold hydrogenation process treatment method provided in an embodiment of the present application.

[0025] Description of reference numerals:

[0026] 10-cold hydrogenation reactor; 20-polysilicon reduction reactor; 30-polysilicon synthesis reactor;

[0027] 200-heat exchanger assembly;

[0028] 300-cyclone separator; 310-first silicon powder receiving tank;

[0029] 400-silicon powder filter; 410-second silicon powder receiving tank;

[0030] 500-quench tower;

[0031] 610-heat exchanger; 620-multiphase flow heat exchanger;

[0032] 710-slurry collecting tank; 711-first slurry collecting tank; 712-second slurry collecting tank; 720-filter; 721-first filter; 722-second filter; 730-slurry processing device;

[0033] 810-silicon tetrachloride storage; 811-transfer pump; 820-circulating hydrogen storage; 830-reduced hydrogen storage; 840-synthetic hydrogen storage;

[0034] 900-vaporizer; 910-condenser; 920-distillation device;

[0035] a-reaction product outlet of cold hydrogenation reactor; b-raw material inlet of cold hydrogenation reactor; c-spray liquid inlet; d-quenching tower inlet; e-bottom exhaust port; f-tower top exhaust port. DETAILED DESCRIPTION

[0036] Polysilicon is the upstream raw material of the photovoltaic and semiconductor industries. It is mainly purified by subjecting industrial silicon powder to a series of chemical treatments to obtain solar-grade polysilicon and electronic-grade crystalline silicon that can be used in the solar and electronics industries.

[0037] The production technology of polysilicon mainly adopts the modified Siemens method. The modified Siemens method is to react industrial silicon powder with hydrogen chloride to process it into trichlorosilane, and then reduce and deposit trichlorosilane in a hydrogen reduction furnace to obtain polysilicon. The tail gas discharged from the reduction furnace contains hydrogen, trichlorosilane, silicon tetrachloride, dichlorosilane and hydrogen chloride, which can be recycled after separation.

[0038] In the production process of polysilicon, a large amount of by-product silicon tetrachloride is produced in the synthesis process of trichlorosilane and the process of hydrogen reduction to produce polysilicon, and is discharged with the tail gas. Silicon tetrachloride is a colorless and transparent liquid at room temperature and pressure, non-polar, volatile, highly irritating, and easily hydrolyzed to produce silicon dioxide and hydrogen chloride, which may cause harm to the environment.

[0039] In the prior art, the byproduct silicon tetrachloride can be treated by various processes such as thermal hydrogenation (direct hydrogenation), cold hydrogenation (hydrogenation with addition of silicon powder), chlorination (addition of hydrogen chloride and silicon powder), high-pressure plasma reduction and catalytic hydrogenation. Among them, the cold hydrogenation process is one of the main development trends at present. Cold hydrogenation is a technology for hydrogenating silicon tetrachloride with silicon powder and a catalyst at a relatively low reaction temperature. Silicon powder and hydrogen are added to a fluidized bed and reacted with silicon tetrachloride to generate trichlorosilane, and the trichlorosilane is sent to the reduction section to be reduced to polysilicon.

[0040] However, due to the different preparation processes of metallurgical-grade silicon powder used as raw materials, key technical indicators such as chemical composition and particle size vary. In addition, silicon powder inevitably contains some metal impurities, such as iron, aluminum, calcium, zinc and other heavy metals. During the cold hydrogenation reaction, metal chlorides such as ferrous chloride and aluminum chloride are easily generated.

[0041] The chlorosilane and hydrogen mixed gas coming out of the reactor contains high-boiling chlorosilanes, metal chlorides and a small amount of fine silicon powder. After being sprayed and washed by the quench tower, the remaining silicon powder, high-boiling chlorosilanes and metal chlorides gradually crystallize and precipitate in the quench tower kettle, which will cause the quench tower residual discharge pipeline to be blocked. In addition, during the process of quench tower residual discharge to slurry collection and treatment, silicon powder, high-boiling chlorosilanes and metal chlorides will also crystallize and precipitate in the slurry collection device, causing the connecting pipeline or slurry collection device to be blocked.

[0042] In order to overcome the defects in the prior art, the present application provides a polysilicon cold hydrogenation process treatment system and treatment method, which is used to treat the reaction products of the cold hydrogenation reactor. The treatment system includes a quenching tower, a heat exchanger, a flushing pipe and a slurry collection and treatment module. Among them, the tower kettle discharge port of the quenching tower is connected to a discharge pipe, and the other end of the discharge pipe is connected to the heat exchanger. The heat exchanger is used to heat and dissolve the high-boiling substances discharged from the quenching tower, and the discharge outlet of the heat exchanger is connected to the slurry collection and treatment module. The outlet end of the flushing pipe is connected to the discharge pipe, and the flushing pipe can be used to inject a flushing medium into the discharge pipe to flush the discharge pipe.

[0043] By introducing a flushing pipe connected to the residual discharge pipe and injecting a flushing medium into the residual discharge pipe to flush the residue in the residual discharge pipe, it is possible to prevent the residual silicon powder, high-boiling chlorosilane and metal chloride crystals from blocking the pipeline and reducing safety hazards. At the same time, the residue will flow into the heat exchanger with the flushing medium, and the heat exchanger can heat and dissolve the high-boiling substances discharged from the quenching tower, so that the high-boiling substances in the residue are further dissolved in the flushing medium, thereby reducing the high-boiling substance content in the residual discharge outlet of the heat exchanger, further reducing the risk of blockage in the pipeline connecting the residual discharge outlet of the heat exchanger and the slurry collection and treatment module, and improving system safety.

[0044] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0045] Figure 1 This is a schematic diagram of the structure of the polysilicon cold hydrogenation process system provided in the embodiment of the present application. Figure 1 As shown, the first aspect of the embodiment of the present application provides a polysilicon cold hydrogenation process treatment system for treating the reaction product of the cold hydrogenation reactor 10, the system comprising: a quenching tower 500, a heat exchanger 610, a flushing pipe and a slurry collection and treatment module. Among them, the tower bottom discharge outlet e of the quenching tower 500 is connected to the heat exchanger 610 through the discharge pipe. The heat exchanger 610 is used to heat and dissolve the high-boiling substances discharged from the quenching tower 500. The slurry collection and treatment module is connected to the discharge outlet of the heat exchanger 610, and can collect and treat the discharge mixture of the heat exchanger 610. The flushing pipe is connected to the discharge pipe, and a flushing medium can be injected into the discharge pipe through the outlet end of the flushing pipe to flush the discharge pipe.

[0046] It is understandable that the flushing medium can be a gaseous substance or a liquid substance, as long as it can dissolve the high-boiling substances in the residue in the drain pipe and does not chemically react with the residue, and it is not specifically limited here.

[0047] With such arrangement, the fine silicon powder remaining in the residual discharge pipe, and the high-boiling chlorosilane products and metal chlorides crystallized in the bottom of the quenching tower 500 can flow into the heat exchanger 610 under the flushing of the flushing medium. Moreover, in the heat exchanger 610, the high-boiling chlorosilane products originally crystallized are dissolved in the flushing medium through the heating treatment of the heat exchanger 610, thereby avoiding the blockage of the residual discharge pipe and reducing the possible blockage risk in the subsequent slurry recovery and processing module, thereby improving the safety of the overall system.

[0048] In some embodiments, the outlet end of the flushing pipe can be arranged near the bottom discharge port e of the tower. In this way, the flushing range of the flushing medium on the discharge pipe can be increased, and the risk of the high-boiling chlorosilane and metal chloride crystallized in the bottom of the quenching tower 500 blocking the discharge pipe can be reduced.

[0049] As an embodiment, the flushing medium may be silicon tetrachloride. The flushing pipe is connected to the silicon tetrachloride storage 810 through a delivery pump 811. The silicon tetrachloride storage 810 may be used to store at least silicon tetrachloride produced in the polysilicon synthesis reactor. Specifically, silicon tetrachloride liquid is stored in the silicon tetrachloride storage 810.

[0050] Such arrangement can further improve the utilization rate of the synthesis byproduct silicon tetrachloride, and no additional flushing medium needs to be provided and stored, thereby simplifying the process flow. The delivery pump 811 can connect the flushing pipe with the silicon tetrachloride storage 810, and deliver the silicon tetrachloride in the silicon tetrachloride storage 810 to a preset position, and can pressurize the silicon tetrachloride and adjust the specific flow rate to meet the flushing requirements.

[0051] Exemplarily, the heat exchanger 610 includes a heat exchange pipe and a shell. The inlet end of the heat exchange pipe is connected to the heating steam supply device, and the outlet end of the heat exchange pipe is connected to the heating steam condensate collection device. Specifically, heating steam with a pressure of 1Mpa can flow in the heat exchange pipe to improve the dissolution of high-boiling chlorosilanes and metal chlorides in the silicon tetrachloride liquid.

[0052] As an embodiment, the system further includes a vaporizer 900, and the heat exchanger 610 further includes a gas outlet, which is connected to the vaporizer 900. The vaporizer 900 can be used to transport the reaction gas to the cold hydrogenation reactor 10. Specifically, the vaporized silicon tetrachloride can be connected to the shell side of the vaporizer 900.

[0053] In this arrangement, when the high-boiling residue discharged from the quench tower 500 is heated and dissolved in the heat exchanger 610, part of the heated silicon tetrachloride liquid will be vaporized and can enter the vaporizer 900 from the gas outlet of the heat exchanger 610, thereby realizing the recovery of silicon tetrachloride. The recovered silicon tetrachloride can continue to participate in the cold hydrogenation reaction as a reactant, thereby improving the recovery rate of silicon tetrachloride.

[0054] It is understood that the vaporizer 900 may be a separate silicon tetrachloride vaporizer 900, and may be connected to the cold hydrogenation reactor 10. The vaporizer 900 originally used to vaporize the reaction gas in the cold hydrogenation reaction process may also be directly used, and is not limited here.

[0055] The slurry collection and processing module includes a slurry collection tank 710, a filter 720 and a slurry processing device 730 which are sequentially connected to the residual discharge outlet of the heat exchanger 610. In the slurry collection tank 710, the residual can be initially separated by sedimentation, so that the heavier solid particles settle to the bottom, so as to facilitate the solid-liquid separation in the subsequent process. The filter 720 can filter out the residual silicon powder, trace chlorosilane high boiling products and metal chlorides in the slurry collection tank 710. It can be understood that since the high boiling products flowing into the slurry collection tank 710 have been thermally dissolved under the flushing of silicon tetrachloride, the content of high boiling products flowing out of the residual discharge outlet of the heat exchanger 610 is significantly reduced, and the frequency of cleaning the filter 720 and the risk of chlorosilane leakage during the cleaning process to endanger personnel are also reduced.

[0056] The slurry treatment device 730 can be used to realize slurry centrifugation, waste liquid gasification, high-temperature hydrolysis, filtration recovery, neutralization condensation, solid drying, water washing emulsification and other processes. Since this part is existing technology, it will not be described in detail here.

[0057] Figure 2 This is a schematic diagram of another polysilicon cold hydrogenation process system provided in an embodiment of the present application. Figure 2 As shown, at least two slurry collecting tanks 710 and filters 720 are provided, and the slurry collecting tanks 710 and filters 720 are provided in a one-to-one correspondence.

[0058] Specifically, taking the example of two slurry collection tanks 710 and two filters 720, the slurry collection tank 710 includes a first slurry collection tank 711 and a second slurry collection tank 712, and the filter 720 includes a first filter 721 and a second filter 722. The first slurry collection tank 711 is connected to the first filter 721, and the second slurry collection tank 712 is connected to the second filter 722. The exhaust outlet of the heat exchanger 610 is connected to the first slurry collection tank 711 and the second slurry collection tank 712 through a connecting pipe, and a control valve is provided on the connecting pipe. The control valve can be used to control the flow direction of the exhaust of the heat exchanger 610. When the exhaust outlet of the heat exchanger 610 is connected to the first slurry collection tank 711, the exhaust outlet of the heat exchanger 610 is not connected to the second slurry collection tank 712.

[0059] Such a configuration can increase the redundancy of the system. By adopting a one-master-one-backup design, when the main slurry collecting tank 710 (such as the first slurry collecting tank 711) is blocked, it can be switched to the auxiliary slurry collecting tank 710 (such as the second slurry collecting tank 712) to work, thereby improving the safety performance of the system.

[0060] The quench tower 500 is also provided with a spray liquid inlet c, which can be connected to the silicon tetrachloride storage 810, thereby improving the utilization rate of the silicon tetrachloride storage 810. The silicon tetrachloride storage 810 is used to store the polysilicon synthesis reactor 30 (see Figure 3 ) and the silicon tetrachloride recovered from the quench tower 500. In addition, the trichlorosilane in the mixed gas can be introduced into the polysilicon reduction reactor 20 (see Figure 3 ) participates in the reduction reaction to generate polycrystalline silicon.

[0061] The quench tower 500 is also provided with a tower top exhaust port f (see Figure 3 ), the tower top exhaust port f and the circulating hydrogen storage 820 (see Figure 3 ), the silicon tetrachloride storage 810 and the polysilicon reduction reactor 20 are connected, so that the reaction product (such as the mixed gas of chlorosilane and hydrogen) in the cold hydrogenation reactor 10 can be recovered. Among them, the circulating hydrogen storage 820 is used to store the circulating hydrogen recovered during the cold hydrogenation reaction, and is connected to the cold hydrogenation reactor 10 to provide hydrogen raw materials for it.

[0062] As an embodiment, the polysilicon cold hydrogenation process system further includes a heat exchanger assembly 200, a cyclone separator 300, and a silicon powder filter 400. The cold hydrogenation reactor 10 is connected to the heat exchanger assembly 200, the cyclone separator 300, the silicon powder filter 400, and the quenching tower 500 in sequence.

[0063] Specifically, the silicon powder filter 400 is connected to the quench tower inlet end d. The cold hydrogenation reactor reaction product outlet end a and the cold hydrogenation reactor reaction product inlet end b are both connected to the heat exchanger assembly 200. It is understood that the heat exchanger assembly 200 may include a feed heater, a plurality of heat exchangers and an electric heater, which are not specifically limited herein.

[0064] The heat exchanger assembly 200 can be used to treat the reaction product to an appropriate temperature, and the cyclone separator 300 can be used to perform primary separation on the reaction product to separate solid matter (such as silicon powder) entrained in the mixed gas. The silicon powder filter 400 can achieve secondary separation of the reaction product, further separating the residual silicon powder in the reaction product, and avoiding the influence of the operation of the subsequent process equipment due to excessive silicon powder content.

[0065] Specifically, the cyclone separator 300 can be connected to the first silicon powder receiving tank 310, and the silicon powder filter 400 can be connected to the second silicon powder receiving tank 410. The residual silicon powder in the cold hydrogenation reaction process can be recovered through the first silicon powder receiving tank 310 and the second silicon powder receiving tank 410, thereby improving the recovery rate and utilization rate of the silicon powder.

[0066] Synthetic by-product hydrogen, reduced by-product hydrogen, recycled hydrogen and silicon tetrachloride can all be used as reactants to participate in the cold hydrogenation reaction.

[0067] In some embodiments, the synthesis by-product hydrogen, the reduction by-product hydrogen, and the recycled hydrogen can be stored in the same gas storage to improve the utilization rate of the device.

[0068] Figure 3 The schematic diagram of the structure of the polysilicon preparation system provided in the embodiment of the present application. As described in the background technology, in the process of preparing polysilicon, the polysilicon preparation system includes a cold hydrogenation reaction system, a synthesis reaction system and a reduction reaction system. Figure 3 As shown, the synthesis reaction system includes a polysilicon synthesis reactor 30 , a synthetic hydrogen storage 840 , a silicon tetrachloride storage 810 and a distillation device 920 .

[0069] In the synthesis reaction system, silicon powder and hydrogen chloride gas undergo a synthesis reaction in the polysilicon synthesis reactor 30 to generate trichlorosilane as the main product, silicon tetrachloride as the byproduct, and hydrogen. The byproduct hydrogen generated after the synthesis is stored in the synthesis hydrogen storage 840 by condensing the reaction products and can enter the vaporizer 900 after being processed by the multiphase flow heat exchanger 620, and then enter the cold hydrogenation reactor 10 from the cold hydrogenation reactor raw material inlet end b to undergo a cold hydrogenation reaction after being controlled to the reaction temperature by the heat exchanger assembly 200.

[0070] The mixture of silicon tetrachloride and trichlorosilane in the synthetic product can be separated by a distillation device 920, wherein the trichlorosilane separated by the distillation device can be transported to the reduction section to participate in the reduction reaction to generate polysilicon. The silicon tetrachloride separated by the distillation device can be transported and stored in the silicon tetrachloride storage 810. Similarly, the silicon tetrachloride in the silicon tetrachloride storage 810 can also be processed by the multiphase flow heat exchanger 620 and then enter the vaporizer 900, and then enter the cold hydrogenation reactor 10 from the raw material inlet end b of the cold hydrogenation reactor to undergo a cold hydrogenation reaction.

[0071] Continue to refer to Figure 3 As shown, the reduction reaction system includes a polysilicon reduction reactor 20 and a reduction hydrogen storage 830. In the reduction reaction system, trichlorosilane enters the polysilicon reduction reactor 20 to undergo a reduction reaction to generate hydrogen and polysilicon. The byproduct hydrogen generated by the reduction reaction can be stored in the reduction hydrogen storage 830, and can be sequentially passed through the multiphase flow heat exchanger 620, the vaporizer 900, and the heat exchanger assembly 200 to enter the cold hydrogenation reactor 10 for use as a raw material.

[0072] It is understandable that since thermal decomposition of trichlorosilane may also occur in the polysilicon reduction reactor 20, silicon tetrachloride produced by the thermal decomposition of trichlorosilane may also be transported to the silicon tetrachloride storage 810 for recycling and storage.

[0073] The cold hydrogenation reaction system includes a polysilicon cold hydrogenation process system and a cold hydrogenation reactant supply system, wherein the cold hydrogenation reactant supply system includes a multiphase flow heat exchanger 620 , a vaporizer 900 , and a heat exchanger assembly 200 .

[0074] It should be noted that the heat exchanger assembly 200 and the vaporizer 900 are involved in both the cold hydrogenation process treatment system and the cold hydrogenation reactant supply system.

[0075] As an implementation mode, the polysilicon cold hydrogenation process treatment system further includes a circulating hydrogen storage 820 , a condenser 910 and a distillation device 920 .

[0076] Specifically, the mixed gas of chlorosilane and hydrogen produced in the cold hydrogenation reactor 10 leaves the quenching tower 500 through the tower top exhaust port f and enters the multiphase flow heat exchanger 620 and the condenser 910 in sequence, and then the hydrogen in the mixed components is separated and transported to the circulating hydrogen storage 820, so as to realize the recycling of the circulating hydrogen in the cold hydrogenation reaction. The remaining chlorosilane mixed solution can be further separated from the silicon tetrachloride and trichlorosilane by the distillation device 920. The separated silicon tetrachloride can be transported to the silicon tetrachloride storage 810 for recycling and storage, and the separated trichlorosilane can be transported to the polysilicon reduction reactor 20 to participate in the reduction reaction to generate polysilicon.

[0077] In the cold hydrogenation reactant supply system, silicon tetrachloride, synthesis by-product hydrogen, reduction by-product hydrogen, and circulating hydrogen are heated in turn by the multiphase flow heat converter 620, the vaporizer 900, and the heat exchanger assembly 200, and then enter the cold hydrogenation reactor 10 to react with the purchased silicon powder to generate a mixed gas of hydrogen, chlorosilane, and metal chloride.

[0078] In some embodiments, the synthesis by-product hydrogen, the reduction by-product hydrogen, and the recycled hydrogen can be stored in the same gas storage to improve the utilization rate of the device.

[0079] Figure 4 This is a schematic diagram of the process flow of the polysilicon cold hydrogenation process provided in the embodiment of the present application. Figure 4 As shown, the second aspect of the present application provides a polysilicon cold hydrogenation process treatment method, which can be applied to any of the polysilicon cold hydrogenation process treatment systems above, and the treatment method includes:

[0080] S100, cooling and washing the mixed gas generated after the reaction in the cold hydrogenation reactor by a quenching tower;

[0081] The quenching tower 500 is connected to the outlet of the cold hydrogenation reactor 10 and is used to cool and wash the mixed gas generated after the reaction of the cold hydrogenation reactor 10 .

[0082] S200, using the flushing medium flowing out of the flushing pipe to flush the residue in the exhaust pipe of the quenching tower, and the residue flows into the heat exchanger along with the flushing medium;

[0083] The flushing pipe is connected to the residual drain pipe, and a flushing medium can be injected into the residual drain pipe through the outlet end of the flushing pipe to flush the residual drain pipe. The flushing medium can transport the residue in the residual drain pipe to the heat exchanger 610.

[0084] S300, heating and dissolving the residue through a heat exchanger;

[0085] After the residue enters the heat exchanger 610, under the heating condition of the heat exchanger 610, the high-boiling chlorosilane in the residue can be dissolved in the flushing medium, thereby reducing the risk of clogging.

[0086] S400, treating the residue discharged from the heat exchanger through a slurry collection and treatment module.

[0087] The slurry collection and processing module is connected to the exhaust outlet of the heat exchanger 610. Since some high-boiling chlorosilanes have been dissolved in the flushing medium in the heat exchanger 610, the risk of blockage in the connecting pipe between the slurry collection and processing module and the heat exchanger 610 is reduced, and the risk of blockage of subsequent process equipment is also reduced.

[0088] In this arrangement, by introducing a flushing pipe connected to the residual discharge pipe and injecting a flushing medium into the residual discharge pipe to flush the residue in the residual discharge pipe, it is possible to prevent residual silicon powder, high-boiling chlorosilanes and metal chloride crystals from clogging the pipeline, thereby reducing safety hazards. At the same time, the residue will flow into the heat exchanger along with the flushing medium, and the heat exchanger can heat and dissolve the high-boiling substances discharged from the quenching tower, so that the high-boiling substances in the residue are further dissolved in the flushing medium. Thus, the content of high-boiling substances in the residual discharge outlet of the heat exchanger is reduced, further reducing the risk of clogging of the connecting pipeline between the heat exchanger and the slurry collection and treatment module, and improving the safety of the system.

[0089] As an embodiment, the flushing medium flowing out of the flushing pipe is silicon tetrachloride, and the treatment method may further include:

[0090] The silicon tetrachloride gas vaporized in the heat exchanger is recovered and sent to a cold hydrogenation reactor to participate in a cold hydrogenation reaction.

[0091] Since silicon tetrachloride itself is the main reactant of the cold hydrogenation reaction, the vaporized silicon tetrachloride can be recovered through the vaporizer 900 and can participate in the cold hydrogenation reaction again, thereby realizing the recycling of silicon tetrachloride and improving its utilization rate.

[0092] In some embodiments, the processing method further comprises:

[0093] Step 1, recovering the mixed gas discharged from the exhaust port at the top of the quenching tower;

[0094] The mixed gas at the top of the quench tower can be recovered through the tower top exhaust port f. The recovered mixed gas is transported to the multiphase flow heat exchanger 620 for heat exchange treatment.

[0095] Step 2, condensing the mixed gas to separate hydrogen, silicon tetrachloride and trichlorosilane;

[0096] The mixed gas is condensed by the condensation device 910 to separate the hydrogen from silicon tetrachloride and trichlorosilane, thereby achieving separate treatment and recovery of different components.

[0097] Step 3, transporting hydrogen to a circulating hydrogen storage tank to participate in the cold hydrogenation reaction again;

[0098] The separated hydrogen can be stored in the circulating hydrogen storage 820 and can be used as a raw material for the cold hydrogenation reactor and enter the cold hydrogenation reactor 10 again for reaction.

[0099] Step 4: Silicon tetrachloride and trichlorosilane are distilled and purified, and the separated silicon tetrachloride is transported to a silicon tetrachloride storage tank to participate in a cold hydrogenation reaction again, and trichlorosilane is transported to a polysilicon reduction reactor to participate in a reduction reaction.

[0100] By distilling and purifying the remaining components, the separated silicon tetrachloride can be introduced into the cold hydrogenation reactor 10 to participate in the reaction again, and the separated and purified trichlorosilane is used as a reactant in the polysilicon reduction process to participate in the polysilicon reduction reaction to generate polysilicon. In this way, the tail gas pollution can be reduced while the utilization rate of the effective components in the reaction product can be improved.

[0101] It should be noted that the phrases "one embodiment", "an embodiment", "an exemplary embodiment", "some embodiments", etc. mentioned in the specification indicate that the described embodiments may include certain features, structures or characteristics, but not every embodiment may include the certain features, structures or characteristics. In addition, such phrases do not necessarily refer to the same embodiment. In addition, when describing certain features, structures or characteristics in conjunction with an embodiment, it is within the knowledge of those skilled in the art to implement such features, structures or characteristics in conjunction with other embodiments, whether explicitly or not explicitly described.

[0102] In general, terms should be understood, at least in part, by the context in which they are used. For example, the term "one or more" as used herein may be used to describe any feature, structure, or characteristic in a singular sense, or may be used to describe a combination of features, structures, or characteristics in a plural sense, depending, at least in part, on the context. Similarly, terms such as "a," "an," or "the" may also be understood to convey singular usage or to convey plural usage, depending, at least in part, on the context.

[0103] It should be easily understood that “on,” “above,” and “over” in this application should be interpreted in the broadest manner, so that “on” not only means “directly on something,” but also includes the meaning of “on something” with intervening features or layers therebetween, and “above” or “over” not only includes the meaning of “above something” or “over,” but also may include the meaning of “above something” or “over” with no intervening features or layers therebetween (i.e., directly on something).

[0104] In addition, spatially relative terms, such as "below," "below," "below," "above," "above," etc., may be used herein for ease of description to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the figures. The device may have other orientations (rotated 90° or at other orientations), and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0105] 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 it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, 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 polysilicon cold hydrogenation process treatment system, used for treating the reaction product of a cold hydrogenation reactor, characterized in that: The processing system comprises: A quenching tower, wherein a residual discharge port of the tower kettle of the quenching tower is connected to a residual discharge pipe; A heat exchanger connected to the other end of the exhaust pipe and used for heating and dissolving the high boiling products discharged from the quenching tower; A flushing pipe, the outlet end of which is connected to the residual drain pipe, and the flushing pipe is used to inject a flushing medium into the residual drain pipe to flush the residual drain pipe; The slurry collection and processing module is connected to the exhaust outlet of the heat exchanger.

2. The polysilicon cold hydrogenation process treatment system according to claim 1, characterized in that: The flushing pipe is connected to the silicon tetrachloride storage tank through a delivery pump; The silicon tetrachloride storage is at least used to store the silicon tetrachloride produced in the polysilicon synthesis reactor.

3. The polysilicon cold hydrogenation process treatment system according to claim 2, characterized in that: Also includes: a vaporizer, the vaporizer being used to deliver reaction gas to the cold hydrogenation reactor; The heat exchanger further comprises a gas outlet connected to the vaporizer.

4. The polysilicon cold hydrogenation process treatment system according to claim 2, characterized in that: The quenching tower is also provided with a spray liquid inlet, and the spray liquid inlet is connected to the silicon tetrachloride storage.

5. The polysilicon cold hydrogenation process treatment system according to any one of claims 1 to 4, characterized in that: The slurry collection and processing module comprises a slurry collection tank, a filter and a slurry processing device which are sequentially connected to the exhaust outlet of the heat exchanger.

6. The polysilicon cold hydrogenation process treatment system according to claim 5, characterized in that: At least two of the slurry collecting tanks and the filters are provided, and the slurry collecting tanks and the filters are provided in a one-to-one correspondence.

7. The polysilicon cold hydrogenation process treatment system according to any one of claims 1 to 4, characterized in that: The quenching tower is provided with a tower top exhaust port, and the tower top exhaust port is connected with a circulating hydrogen storage tank, a silicon tetrachloride storage tank and a polysilicon reduction reactor.

8. The polysilicon cold hydrogenation process treatment system according to any one of claims 1 to 4, characterized in that: The polysilicon cold hydrogenation process treatment system also includes a cyclone separator and a silicon powder filter; The cold hydrogenation reactor is connected to the cyclone separator, the silicon powder filter and the quenching tower in sequence.

9. A polysilicon cold hydrogenation process treatment method, applied to the polysilicon cold hydrogenation process treatment system according to any one of claims 1 to 8, characterized in that: The processing method comprises: The mixed gas generated after the reaction in the cold hydrogenation reactor is cooled and washed by a quenching tower; The residue in the exhaust pipe of the quench tower is washed with the flushing medium flowing out of the flushing pipe, and the residue flows into the heat exchanger along with the flushing medium; The residue is subjected to a heating and dissolving treatment by the heat exchanger; The residue discharged from the heat exchanger is processed by a slurry collection and processing module.

10. The polysilicon cold hydrogenation process according to claim 9, characterized in that: The flushing medium flowing out of the flushing pipe is silicon tetrachloride, and the treatment method further comprises: The silicon tetrachloride gas vaporized in the heat exchanger is recovered, and the recovered silicon tetrachloride gas is sent to the cold hydrogenation reactor to participate in the cold hydrogenation reaction.

11. The polysilicon cold hydrogenation process according to claim 9, characterized in that: The processing method also includes: Recovering the mixed gas discharged from the exhaust port at the top of the quenching tower; Condensing the mixed gas to separate hydrogen, silicon tetrachloride and trichlorosilane; The hydrogen is transported to a circulating hydrogen storage device to participate in the cold hydrogenation reaction again; Silicon tetrachloride and trichlorosilane are distilled and purified, and the separated silicon tetrachloride is transported to a silicon tetrachloride storage tank to participate in cold hydrogenation reaction again, and trichlorosilane is transported to a polysilicon reduction reactor to participate in reduction reaction.

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