Polysilicon reduction furnace series operation method and system capable of online monitoring

Abstract

The application discloses a kind of polycrystalline silicon reduction furnace series operation method and system of on-line monitoring, and the first tail gas is exchanged by jacket and tail gas pipeline heat exchanger;First tail gas enters tail gas mixer, and gas chromatograph is arranged in tail gas mixer, and the component content in first tail gas is detected in real time, and the system supplements H2 and SiHCl3 according to each component content;Mixed gas is transported to the later batch reduction furnace;Second tail gas discharged from the later batch reduction furnace enters recovery system separation processing, by the series connection of the former batch reduction furnace and tail gas mixer and the later batch reduction furnace, so that the later batch reduction furnace after series connection does not need steam to heat raw materials, greatly save the steam consumption, and the feed temperature of the later batch reduction furnace is controlled at 350 DEG C, by the series connection of the former batch reduction furnace and tail gas mixer and the later batch reduction furnace, so that the thermal field and gas field in reduction furnace remain stable, and silicon powder and liquid material are not easy to produce, thereby improving the controllability of reduction furnace.

Description

Technical Field

[0001] This invention relates to the field of reduction furnace equipment technology, and in particular to a method and system for online monitoring of series operation of polycrystalline silicon reduction furnaces. Background Technology

[0002] The polysilicon reduction furnace is the core equipment in polysilicon production, producing the final product. Its process is also a key factor determining system capacity and energy consumption. Therefore, the design of the polysilicon reduction furnace process directly affects product quality, yield, and production costs. Current reduction furnace production processes involve a single furnace. The reaction exhaust gas is cooled by high-temperature water and then sent to the exhaust gas recovery system. This results in significant energy losses and high production costs during polysilicon reduction. Furthermore, the temperature of the mixed gas is not constant throughout the reduction process, leading to instability in the internal thermal field of the furnace and introducing instability factors into the overall furnace control.

[0003] In existing technologies, the gas-phase precipitation reaction in the reduction furnace is an endothermic reaction, requiring a temperature of approximately 1180-1250°C. The raw material gas for the reduction furnace needs to be continuously heated to approximately 160°C before entering the furnace for reaction. Increasing the feed temperature would reduce energy consumption but would significantly increase heating costs. Furthermore, existing technologies also disclose a reaction system and operating method for producing polycrystalline silicon using multiple polycrystalline silicon reduction furnaces. This system includes multiple polycrystalline silicon reduction furnaces and a heat exchanger. The multiple polycrystalline silicon reduction furnaces are connected in series. Except for the first reduction furnace, the other reduction furnaces... The feed inlet is connected to the outlet of the adjacent previous reduction furnace, and a hydrogen supply pipeline is connected between the feed inlet and the outlet. In this system, the two inlets of the heat exchanger are connected to the feed pipe and the outlet of the last reduction furnace, respectively, and the two outlets are connected to the feed inlet of the first reduction furnace and the final exhaust outlet, respectively. However, since multiple reduction furnaces are operated in series, if any one of them experiences an abnormal shutdown such as a furnace collapse, it will affect the production of subsequent reduction furnaces and cause huge economic losses. Therefore, this method does not have the possibility of continuous industrial production. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a method and system for online monitoring of series operation of polycrystalline silicon reduction furnaces, the main purpose of which is to provide an online monitoring method for series operation of polycrystalline silicon reduction furnaces that can reduce the production energy consumption of the reduction furnace.

[0005] To achieve the above objectives, the present invention mainly provides the following technical solutions:

[0006] On one hand, embodiments of the present invention provide a method for online monitoring of series operation of polycrystalline silicon reduction furnaces, the method comprising the following steps:

[0007] The previous batch of reduction furnaces operated under standard conditions, and the temperature of the first tail gas discharged from the previous batch of reduction furnaces was 320℃ to 380℃.

[0008] The first exhaust gas undergoes heat exchange through a jacket and exhaust gas pipeline heat exchanger, keeping the temperature of the first exhaust gas stable at 340°C to 360°C.

[0009] The first tail gas enters the tail gas mixer, which is equipped with a gas chromatograph to detect the content of SiHCl3, SiCl4, SiH2Cl2, HCl and H2 in the first tail gas in real time. The system replenishes H2 and SiHCl3 according to the content of each component. H2, SiHCl3 and the first tail gas form a mixed gas, and the temperature of the mixed gas is maintained at 345 ℃–355 ℃.

[0010] The mixed gas is then conveyed to the subsequent reduction furnace;

[0011] The second tail gas discharged from the subsequent reduction furnace enters the recovery system for separation and treatment.

[0012] Furthermore, in the supplementary H2 and SiHCl3, the volume ratio of H2:SiHCl3 is 3:1–4:1.

[0013] Furthermore, the volume fraction of SiHCl3 in the mixed gas is 15%–20%.

[0014] Furthermore, the surface temperature of the silicon rod in the first batch reduction furnace is 1080 ℃–1220 ℃, the furnace pressure is 0.4 MPa–0.6 MPa, and the mass concentrations of each component in the first tail gas are: SiHCl3: 43.0%–49.0%, SiCl4: 45.0%–20.0%, SiH2Cl2: 4.0%–13.2%, HCl: 0.05%–7.2%, and H2: 0.15%–11.1%.

[0015] Furthermore, the volume of the tail gas mixer is 1 / 10–1 / 8 of the batch gas volume processed by the previous reduction furnace, and the design pressure is 0.8 MPa.

[0016] On the other hand, embodiments of the present invention also provide a series operation system for polysilicon reduction furnaces that can be monitored online, the system comprising:

[0017] The first reduction furnace component includes a first inlet pipe, a first exhaust pipe, a tail gas pipe heat exchanger, and a plurality of pre-batch reduction furnaces. The first inlet pipe is connected to each of the pre-batch reduction furnaces, and one end of the first exhaust pipe is connected to each of the pre-batch reduction furnaces, while the other end is connected to the tail gas pipe heat exchanger.

[0018] The mixing component includes an exhaust gas mixer, a gas chromatograph, a hydrogen input component, and a trichlorosilane input component. The gas chromatograph is installed inside the exhaust gas mixer and is used to detect the component content of the exhaust gas. The exhaust gas pipeline heat exchanger, the hydrogen input component, and the trichlorosilane input component are connected to the exhaust gas mixer. The gas chromatograph signal is connected to the hydrogen input component and the trichlorosilane input component.

[0019] The second reduction furnace component includes a second air inlet pipe, a second exhaust pipe, and a plurality of subsequent batch reduction furnaces. One end of the first air inlet pipe is connected to the exhaust gas mixer, and the other end is connected to each of the subsequent batch reduction furnaces. One end of the second exhaust pipe is connected to each of the subsequent batch reduction furnaces.

[0020] Furthermore, the hydrogen input component includes a hydrogen pipeline and a hydrogen regulating valve, the hydrogen regulating valve being disposed on the hydrogen pipeline; the trichlorosilane input component includes the trichlorosilane pipeline and the trichlorosilane regulating valve, the trichlorosilane regulating valve being disposed on the trichlorosilane pipeline.

[0021] Furthermore, the number of the plurality of pre-batch reduction furnaces and the plurality of post-batch reduction furnaces are the same.

[0022] Furthermore, the exhaust gas pipeline heat exchanger includes a tube side and a shell side, with the two ends of the tube side connected to the first exhaust pipeline and the exhaust gas mixer, respectively, and the shell side connected to a low-pressure steam pipeline.

[0023] The beneficial effects of this invention are as follows:

[0024] By connecting the pre-reduction furnace, the tail gas mixer, and the post-reduction furnace in series, the post-reduction furnace does not require steam to heat the raw materials, which greatly saves steam consumption. Furthermore, the feed temperature of the post-reduction furnace is controlled at 350℃, and the power consumption to maintain the heat of the silicon rod is reduced by 20% during the operating cycle.

[0025] By sending the tail gas generated by the previous batch of reduction furnaces to the tail gas mixer for mixing, and then sending the mixed gas to the subsequent batch of reduction furnaces for continued use, the tail gas recovery system requires a large amount of cold and heat sources in the process of separating hydrogen and chlorosilanes. Therefore, the primary conversion rate of reduction is increased from 10% to 17% for two units in series, and the energy consumption of the tail gas recovery system is reduced by 10%.

[0026] By connecting the first batch reduction furnace, the tail gas mixer, and the subsequent batch reduction furnace in series, the thermal and gas fields inside the reduction furnace are kept stable, making it less likely to produce silicon powder and liquid materials, thereby improving the controllability of the reduction furnace. Attached Figure Description

[0027] Figure 1 A flowchart illustrating a method for online monitoring of a polycrystalline silicon reduction furnace in series operation, as provided in an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of a series operation system for polycrystalline silicon reduction furnaces that can be monitored online, provided as an embodiment of the present invention.

[0029] Figure 3 A flowchart of another online-monitorable polycrystalline silicon reduction furnace series operation method provided in an embodiment of the present invention. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0031] On the one hand, such as Figure 1 and Figure 2 As shown, this embodiment of the invention provides a method for online monitoring of polycrystalline silicon reduction furnaces operating in series, the method comprising the following steps:

[0032] The previous batch of reduction furnaces operated under standard conditions, and the temperature of the first tail gas discharged from the previous batch of reduction furnaces was 320℃ to 380℃.

[0033] The first exhaust gas undergoes heat exchange through a jacket and exhaust gas pipeline heat exchanger, keeping the temperature of the first exhaust gas stable at 340°C to 360°C.

[0034] The first tail gas enters the tail gas mixer, which is equipped with a gas chromatograph to detect the content of SiHCl3, SiCl4, SiH2Cl2, HCl and H2 in the first tail gas in real time. The system replenishes H2 and SiHCl3 according to the content of each component. H2, SiHCl3 and the first tail gas form a mixed gas, and the temperature of the mixed gas is maintained at 345 ℃–355 ℃.

[0035] The mixed gas is then conveyed to the subsequent reduction furnace;

[0036] The second tail gas discharged from the subsequent reduction furnace enters the recovery system for separation and treatment.

[0037] The beneficial effects of this invention are as follows:

[0038] By connecting the pre-reduction furnace, the tail gas mixer, and the post-reduction furnace in series, the post-reduction furnace does not require steam to heat the raw materials, which greatly saves steam consumption. Furthermore, the feed temperature of the post-reduction furnace is controlled at 350℃, and the power consumption to maintain the heat of the silicon rod is reduced by 20% during the operating cycle.

[0039] By sending the tail gas generated by the previous batch of reduction furnaces to the tail gas mixer for mixing, and then sending the mixed gas to the subsequent batch of reduction furnaces for continued use, the tail gas recovery system requires a large amount of cold and heat sources in the process of separating hydrogen and chlorosilanes. Therefore, the primary conversion rate of reduction is increased from 10% to 17% for two units in series, and the energy consumption of the tail gas recovery system is reduced by 10%.

[0040] By connecting the first batch reduction furnace, the tail gas mixer, and the subsequent batch reduction furnace in series, the thermal and gas fields inside the reduction furnace are kept stable, making it less likely to produce silicon powder and liquid materials, thereby improving the controllability of the reduction furnace.

[0041] Example 1

[0042] like Figure 1 and Figure 2 As shown, this embodiment of the invention provides a method for online monitoring of polycrystalline silicon reduction furnaces operating in series, the method comprising the following steps:

[0043] 101. The first batch of reduction furnaces operated under standard conditions, and the temperature of the first tail gas discharged from the first batch of reduction furnaces was 320℃ to 380℃.

[0044] There are three pre-reduction furnaces, which operate under standard conditions, controlling the silicon rod surface temperature between 1080 ℃ and 1220 ℃, preferably 1090 ℃, 1100 ℃, and 1110 ℃, and the furnace pressure between 0.4 MPa and 0.6 MPa, preferably 0.5 MPa. The temperature of the first tail gas discharged from the pre-reduction furnace is between 320 ℃ and 380 ℃, preferably 330 ℃, 340 ℃, 350 ℃, 360 ℃, and 370 ℃. The mass concentrations of each component in the first tail gas are as follows: SiHCl3: 43.0%–49.0%, SiCl4: 45.0%–20.0%, SiH2Cl2: 4.0%–13.2%, HCl: 0.05%–7.2%, and H2: 0.15%–11.1%.

[0045] 102. The first exhaust gas undergoes heat exchange through the jacket and exhaust gas pipeline heat exchanger, so that the temperature of the first exhaust gas is stably maintained at 340℃ to 360℃.

[0046] The first tail gas exchanges heat with the circulating cooling water through the jacket of the bell jar of the reduction furnace and the tail gas pipeline heat exchanger. The temperature of the first tail gas after heat exchange is maintained at 340°C to 360°C, preferably 350°C. The by-product after heat exchange is low-pressure steam of 0.3 MPa–0.5 MPa, which is then transported to other equipment in the plant area for use.

[0047] 103. The first tail gas enters the tail gas mixer. A gas chromatograph is installed in the tail gas mixer to detect the content of SiHCl3, SiCl4, SiH2Cl2, HCl and H2 in the first tail gas in real time. The system replenishes H2 and SiHCl3 according to the content of each component. H2, SiHCl3 and the first tail gas form a mixed gas, and the temperature of the mixed gas is maintained at 345 ℃–355 ℃.

[0048] The first batch of exhaust gas enters the exhaust gas mixer, whose volume is 1 / 10–1 / 8 of the single-batch gas volume processed by the previous reduction furnace, and whose design pressure is 0.8. The pressure is measured in MPa. Furthermore, the tail gas mixer is equipped with baffles and a heat tracing and insulation device to maintain the temperature within the mixer. Simultaneously, a gas chromatograph is installed within the tail gas mixer to monitor the content of each component in the first tail gas in real time. The first tail gas contains SiHCl3, SiCl4, SiH2Cl2, HCl, and H2. Based on the gas chromatograph data, the control system precisely matches the material concentration required for the subsequent batch reduction furnace reaction to replenish new H2 and SiHCl3 into the tail gas mixer. Specifically, according to the pre-set process ratio, the volume ratio of H2:SiHCl3 is 3:1–4:1. Fresh hydrogen and trichlorosilane raw materials are quantitatively injected, and H2, SiHCl3, and the first tail gas mix to form a mixed gas. The volume fraction of SiHCl3 in the mixed gas is adjusted to 15%–20%. Simultaneously, the heat tracing and insulation device in the tail gas mixer maintains a uniform temperature of the mixed gas at 345 ℃–355 ℃, enabling the tail gas mixer to perform a triple function of pressure stabilization, temperature uniformity, and mass homogenization.

[0049] 104. The mixed gas is then transported to the subsequent reduction furnace.

[0050] The tail gas mixer delivers the mixed gas at 350°C to the inlet at the bottom of the subsequent reduction furnace. Since the temperature of the mixed gas is 350°C, there is no need to preheat the gas entering the subsequent reduction furnace. The silicon rods in the subsequent reduction furnace are energized to maintain the reaction temperature. Due to the significant increase in the feed temperature, the electrical power required to maintain the thermal field is greatly reduced.

[0051] 105. The second tail gas discharged from the subsequent reduction furnace enters the recovery system for separation and treatment.

[0052] The temperature of the second tail gas discharged from the subsequent reduction furnace is 350 ℃. The second tail gas enters the recovery system through the tail gas main pipeline for separation treatment. The separated H2 and SiHCl3 are purified and returned to the reduction process for recycling.

[0053] The beneficial effects of this invention are as follows:

[0054] By connecting the pre-reduction furnace, the tail gas mixer, and the post-reduction furnace in series, the post-reduction furnace does not require steam to heat the raw materials, which greatly saves steam consumption. Furthermore, the feed temperature of the post-reduction furnace is controlled at 350℃, and the power consumption to maintain the heat of the silicon rod is reduced by 20% during the operating cycle.

[0055] By sending the tail gas generated by the previous batch of reduction furnaces to the tail gas mixer for mixing, and then sending the mixed gas to the subsequent batch of reduction furnaces for continued use, the tail gas recovery system requires a large amount of cold and heat sources in the process of separating hydrogen and chlorosilanes. Therefore, the primary conversion rate of reduction is increased from 10% to 17% for two units in series, and the energy consumption of the tail gas recovery system is reduced by 10%.

[0056] By connecting the first batch reduction furnace, the tail gas mixer, and the subsequent batch reduction furnace in series, the thermal and gas fields inside the reduction furnace are kept stable, making it less likely to produce silicon powder and liquid materials, thereby improving the controllability of the reduction furnace.

[0057] Example 2

[0058] This invention provides a method for online monitoring of the series operation of polycrystalline silicon reduction furnaces. The difference between this method and the method in Embodiment 1 is that continuous production is achieved by controlling the staggered operation of the preceding and subsequent batches of reduction furnaces. Specifically, the method includes the following steps:

[0059] 201. The first batch of reduction furnaces shall sequentially perform continuous production operation, furnace start-up material preparation operation and furnace shutdown cleaning operation, and the subsequent batch of reduction furnaces shall sequentially perform continuous production operation, furnace start-up material preparation operation and furnace shutdown cleaning operation.

[0060] The first batch of reduction furnaces includes the first reduction furnace, the second reduction furnace, and the third reduction furnace. The second batch of reduction furnaces includes the fourth reduction furnace, the fifth reduction furnace, and the sixth reduction furnace. The first reduction furnace performs continuous production operations, the second reduction furnace performs furnace start-up and material preparation operations, the third reduction furnace performs furnace shutdown and cleaning operations, the fourth reduction furnace performs continuous production operations and chemical vapor deposition reactions using the first tail gas generated by the first reduction furnace and supplemented H2 and SiHCl3, the fifth reduction furnace performs furnace start-up and material preparation operations, and the sixth reduction furnace performs furnace shutdown and cleaning operations.

[0061] 202. The first batch of reduction furnaces shall sequentially perform furnace shutdown and cleaning operations, continuous production operations, and furnace start-up and material preparation operations. The subsequent batch of reduction furnaces shall sequentially perform furnace shutdown and cleaning operations, continuous production operations, and furnace start-up and material preparation operations.

[0062] After the first reduction furnace completes its production cycle, it shuts down to complete the unloading, dismantling, and cleaning of the furnace body. The second reduction furnace then begins continuous production, generating the first tail gas. The third reduction furnace performs pre-treatment for start-up, becoming ready for production. The fourth reduction furnace shuts down to complete the unloading, dismantling, and cleaning of the furnace body. The fifth reduction furnace then performs continuous production using the first tail gas generated by the first reduction furnace and supplemented with H2 and SiHCl3, and conducts chemical vapor deposition reactions. The sixth reduction furnace performs pre-treatment for start-up.

[0063] 203. The first batch of reduction furnaces shall sequentially perform furnace start-up preparation, furnace shutdown cleaning and continuous production operations, and the subsequent batch of reduction furnaces shall sequentially perform furnace start-up preparation, furnace shutdown cleaning and continuous production operations.

[0064] After the second reduction furnace completes its production cycle, it shuts down to complete the unloading, dismantling, and cleaning of the furnace body. The first reduction furnace performs pre-treatment for start-up and is ready for production. The third reduction furnace performs continuous production and generates the first tail gas. The fifth reduction furnace shuts down to complete the unloading, dismantling, and cleaning of the furnace body. The fourth reduction furnace performs pre-treatment for start-up. The sixth reduction furnace performs continuous production and chemical vapor deposition reaction using the first tail gas generated by the third reduction furnace and supplemented H2 and SiHCl3.

[0065] Based on 6 reduction furnaces, the number of reduction furnaces can be increased in even numbers, with the first and second batches increasing simultaneously. For example, it can be increased to 60 reduction furnaces, with 30 as the first batch and 30 as the second batch. The 30 first batch reduction furnaces ensure that they are simultaneously in three working conditions: steady-state continuous production, furnace shutdown for dismantling and cleaning, and furnace start-up for material preparation and pretreatment. This effectively ensures that the 30 second batch reduction furnaces have sufficient reactive gas for chemical vapor deposition reaction.

[0066] The beneficial effects of this invention are as follows:

[0067] This embodiment achieves staggered operation of the preceding reduction furnaces, allowing them to simultaneously undertake different process operations. The subsequent reduction furnaces then use the tail gas and supplemented hydrogen / trichlorosilane provided by the preceding reduction furnaces for chemical vapor deposition, effectively avoiding process conflicts and improving operational efficiency.

[0068] In this embodiment, by cyclically rotating and sequentially putting each furnace station into operation, the problem of the entire production line being shut down due to the shutdown of a single reduction furnace or the dismantling of the furnace is completely solved, effectively ensuring the stability and continuity of the series reduction production process and achieving long-term stable operation of the equipment.

[0069] On the other hand, embodiments of the present invention also provide a series operation system for polysilicon reduction furnaces that can be monitored online, the system comprising:

[0070] The first reduction furnace component includes a first air inlet pipe 11, a first exhaust pipe 12, a tail gas pipe heat exchanger 13, and a plurality of pre-batch reduction furnaces 14. The first air inlet pipe 11 is connected to each of the pre-batch reduction furnaces 14. One end of the first exhaust pipe 12 is connected to each of the pre-batch reduction furnaces 14, and the other end is connected to the tail gas pipe heat exchanger 13.

[0071] The mixing component includes an exhaust gas mixer 21, a gas chromatograph 22, a hydrogen input component, and a trichlorosilane input component. The gas chromatograph 22 is disposed in the exhaust gas mixer 21 and is used to detect the component content of the exhaust gas. The exhaust gas pipeline heat exchanger 13, the hydrogen input component, and the trichlorosilane input component are connected to the exhaust gas mixer 21. The gas chromatograph 22 is connected to the hydrogen input component and the trichlorosilane input component.

[0072] The second reduction furnace component includes a second air inlet pipe 31, a second exhaust pipe 32, and a plurality of subsequent batch reduction furnaces 33. One end of the first air inlet pipe 11 is connected to the exhaust gas mixer 21, and the other end is connected to each of the subsequent batch reduction furnaces 33. One end of the second exhaust pipe 32 is connected to each of the subsequent batch reduction furnaces 33.

[0073] The aforementioned first reduction furnace component includes a first inlet pipe 11, a first exhaust pipe 12, a tail gas pipe heat exchanger 13, and multiple pre-batch reduction furnaces 14. The first inlet pipe 11 is connected to each of the pre-batch reduction furnaces 14. One end of the first exhaust pipe 12 is connected to each of the pre-batch reduction furnaces 14, and the other end is connected to the tail gas pipe heat exchanger 13. One end of the first inlet pipe 11 is connected to a gas supply device for supplying H2 and SiHCl3 to the multiple pre-batch reduction furnaces 14. The other end of the first inlet pipe 11 is connected to each of the pre-batch reduction furnaces 14 via pipes and valves. Multiple pre-batch reduction furnaces 14 are connected in parallel, and valves are installed on the pipelines to control the gas entering different pre-batch reduction furnaces 14. The exhaust end of the pre-batch reduction furnace 14 is connected to the first exhaust pipeline 12 through pipelines and valves to control the tail gas generated by the pre-batch reduction furnace 14 at different locations to enter the tail gas pipeline heat exchanger 13. The tail gas pipeline heat exchanger 13 exchanges heat with the first tail gas generated by the pre-batch reduction furnace 14 to maintain the temperature of the first tail gas between 340°C and 360°C. The function of the mixing component is to mix the first tail gas. The system includes an exhaust gas mixer 21, a gas chromatograph 22, a hydrogen input component, and a trichlorosilane input component. The gas chromatograph 22 is installed inside the exhaust gas mixer 21 and is used to detect the component content of the exhaust gas. The exhaust gas pipeline heat exchanger, the hydrogen input component, and the trichlorosilane input component are connected to the exhaust gas mixer 21. The gas chromatograph 22 is connected to the hydrogen input component and the trichlorosilane input component. The gas chromatograph 22 is installed in the exhaust gas mixer 21 and is used to detect the content of each component in the mixer in real time. Among them, the components in the first exhaust gas... The mixture includes SiHCl3, SiCl4, SiH2Cl2, HCl, and H2. The gas chromatograph 22 uploads the content of each component to the overall control system. Based on the detection data, the overall control system adjusts the amount of hydrogen and trichlorosilane supplied to the tail gas mixer 21 by the hydrogen input component and the trichlorosilane input component, precisely matching the material concentration required for the reaction. This allows the first tail gas, hydrogen, and trichlorosilane to mix in the tail gas mixer 21 to form a mixed gas. The volume fraction of SiHCl3 in the mixed gas is adjusted to 15%–20%. At the same time, the mixer ensures that the gas temperature is maintained at 345 ℃–355 ℃. The mixer plays a triple role of stabilizing pressure, equalizing temperature, and homogenizing mass.The second reduction furnace component includes a second inlet pipe 31, a second exhaust pipe 32, and multiple subsequent batch reduction furnaces 33. One end of the first inlet pipe 11 is connected to the tail gas mixer 21, and the other end is connected to each of the subsequent batch reduction furnaces 33. One end of the second exhaust pipe 32 is connected to each of the subsequent batch reduction furnaces 33. The mixed gas is transported through the second inlet pipe 31 to one of the required subsequent batch reduction furnaces 33 for use and reaction. The second tail gas generated after the reaction is discharged through the second exhaust pipe 32 and enters the recovery system for recycling. The number of the multiple preceding batch reduction furnaces 14 and the multiple subsequent batch reduction furnaces 33 is the same. In this technical solution, the preceding batch reduction furnaces 14 are connected in series with the tail gas mixer 21 and the subsequent batch reduction furnaces 33, so that the series-connected subsequent batch reduction furnaces 33 No steam is needed to heat the raw materials, significantly saving steam consumption. Furthermore, the feed temperature of the subsequent reduction furnace 33 is controlled at 350℃, reducing the electrical energy consumption for maintaining the silicon rod's heat by 20% during the operating cycle. The exhaust gas generated by the preceding reduction furnace 14 is mixed in the exhaust gas mixer 21, and then the mixed gas is fed back into the subsequent reduction furnace 33 for reuse. Since the exhaust gas recovery system requires a large amount of cooling and heating energy during the separation of hydrogen and chlorosilanes, the primary conversion rate of the reduction furnace is increased from 10% to 17% for two units connected in series, and the energy consumption of the exhaust gas recovery system is reduced by 10%. By connecting the preceding reduction furnace 14, the exhaust gas mixer 21, and the subsequent reduction furnace 33 in series, the thermal and gas fields within the reduction furnace remain stable, reducing the likelihood of silicon powder and liquid material buildup, thereby improving the controllability of the reduction furnace.

[0074] Furthermore, the hydrogen input component includes a hydrogen pipeline 231 and a hydrogen regulating valve 232, the hydrogen regulating valve 232 being disposed on the hydrogen pipeline 231. The trichlorosilane input component includes the trichlorosilane pipeline 241 and a trichlorosilane regulating valve 242, the trichlorosilane regulating valve 242 being disposed on the trichlorosilane pipeline 241. In this embodiment, the hydrogen input component and the trichlorosilane input component are further defined. The hydrogen input component includes a hydrogen pipeline 231 and a hydrogen regulating valve 232, the hydrogen regulating valve 232 being disposed on the hydrogen pipeline 231. One end of the hydrogen pipeline 231 is connected to a hydrogen supply device, and the other end is connected to a tail gas mixer 21. The trichlorosilane input component includes the trichlorosilane pipeline 241 and a trichlorosilane regulating valve 242, the trichlorosilane regulating valve 242 being disposed on the trichlorosilane pipeline 241. One end of the silicon pipe 241 is connected to the trichlorosilane supply equipment, and the other end is connected to the tail gas mixer 21. The hydrogen regulating valve 232 is connected to the main control system 8 via wires or signals, and the trichlorosilane regulating valve 242 is connected to the main control system 8 via wires or signals. The gas chromatograph 22 uploads the content of each component to the main control system 8. The main control system 8 remotely adjusts the opening of the hydrogen regulating valve 232 and the trichlorosilane regulating valve 242 according to the detection data, thereby achieving the technical effect of controlling the replenishment of hydrogen and trichlorosilane.

[0075] Furthermore, the exhaust gas pipeline heat exchanger 13 includes a tube side and a shell side. The two ends of the tube side are respectively connected to the first exhaust pipeline 12 and the exhaust gas mixer 21, and the shell side is connected to the low-pressure steam pipeline 9. In this embodiment, the exhaust gas pipeline heat exchanger 13 is further defined, with the two ends of the tube side connected to the first exhaust pipeline 12 and the exhaust gas mixer 21. The first exhaust gas exchanges heat with the circulating cooling water in the shell side through the jacket of the reduction furnace bell jar and the tube side of the exhaust gas pipeline heat exchanger 13. The temperature of the first exhaust gas after heat exchange is maintained at 340°C to 360°C. The by-product after heat exchange is low-pressure steam of 0.3MPa–0.5MPa. The low-pressure steam is transported to other equipment in the plant area through the low-pressure steam pipeline 9 for use, thereby achieving the technical effect of heating low-pressure steam.

[0076] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for online monitoring of polycrystalline silicon reduction furnaces operating in series, characterized in that, Includes the following steps: The previous batch of reduction furnaces operated under standard conditions, and the temperature of the first tail gas discharged from the previous batch of reduction furnaces was 320℃ to 380℃. The first exhaust gas undergoes heat exchange through a jacket and exhaust gas pipeline heat exchanger, keeping the temperature of the first exhaust gas stable at 340°C to 360°C. The first tail gas enters the tail gas mixer, which is equipped with a gas chromatograph to detect the content of SiHCl3, SiCl4, SiH2Cl2, HCl and H2 in the first tail gas in real time. The system replenishes H2 and SiHCl3 according to the content of each component. H2, SiHCl3 and the first tail gas form a mixed gas, and the temperature of the mixed gas is maintained at 345 ℃–355 ℃. The mixed gas is then conveyed to the subsequent reduction furnace; The second tail gas discharged from the subsequent reduction furnace enters the recovery system for separation and treatment.

2. The method for online monitoring of a polycrystalline silicon reduction furnace in series operation according to claim 1, characterized in that, In the supplementary H2 and SiHCl3, the volume ratio of H2:SiHCl3 is 3:1–4:

1.

3. The method for online monitoring of a polycrystalline silicon reduction furnace in series operation according to claim 2, characterized in that, The volume fraction of SiHCl3 in the mixed gas is 15%–20%.

4. The method for online monitoring of a polycrystalline silicon reduction furnace in series operation according to claim 1, characterized in that, The surface temperature of the silicon rods in the first batch reduction furnace is 1080 ℃–1220 ℃, the furnace pressure is 0.4 MPa–0.6 MPa, and the mass concentrations of each component in the first tail gas are: SiHCl3: 43.0%–49.0%, SiCl4: 45.0%–20.0%, SiH2Cl2: 4.0%–13.2%, HCl: 0.05%–7.2%, and H2: 0.15%–11.1%.

5. A method for online monitoring of a polycrystalline silicon reduction furnace in series operation according to claim 1, characterized in that, The volume of the tail gas mixer is 1 / 10–1 / 8 of the gas volume processed by the previous batch reduction furnace, and the design pressure is 0.8 MPa.

6. A series operation system for an online-monitorable polycrystalline silicon reduction furnace used in the method of claim 1, characterized in that, include: The first reduction furnace component includes a first inlet pipe, a first exhaust pipe, a tail gas pipe heat exchanger, and a plurality of pre-batch reduction furnaces. The first inlet pipe is connected to each of the pre-batch reduction furnaces, and one end of the first exhaust pipe is connected to each of the pre-batch reduction furnaces, while the other end is connected to the tail gas pipe heat exchanger. The mixing component includes an exhaust gas mixer, a gas chromatograph, a hydrogen input component, and a trichlorosilane input component. The gas chromatograph is installed inside the exhaust gas mixer and is used to detect the component content of the exhaust gas. The exhaust gas pipeline heat exchanger, the hydrogen input component, and the trichlorosilane input component are connected to the exhaust gas mixer. The gas chromatograph signal is connected to the hydrogen input component and the trichlorosilane input component. The second reduction furnace component includes a second air inlet pipe, a second exhaust pipe, and a plurality of subsequent batch reduction furnaces. One end of the first air inlet pipe is connected to the exhaust gas mixer, and the other end is connected to each of the subsequent batch reduction furnaces. One end of the second exhaust pipe is connected to each of the subsequent batch reduction furnaces.

7. The series operation system for polycrystalline silicon reduction furnaces capable of online monitoring according to claim 6, characterized in that, The hydrogen input component includes a hydrogen pipeline and a hydrogen regulating valve, the hydrogen regulating valve being disposed on the hydrogen pipeline. The trichlorosilane input component includes the trichlorosilane pipeline and a trichlorosilane regulating valve, the trichlorosilane regulating valve being disposed on the trichlorosilane pipeline.

8. A series operation system for polycrystalline silicon reduction furnaces capable of online monitoring according to claim 6, characterized in that, The number of the multiple first-batch reduction furnaces and the multiple second-batch reduction furnaces are the same.

9. A series operation system for polycrystalline silicon reduction furnaces capable of online monitoring according to claim 6, characterized in that, The exhaust gas pipeline heat exchanger includes a tube side and a shell side. The two ends of the tube side are respectively connected to the first exhaust pipeline and the exhaust gas mixer, and the shell side is connected to a low-pressure steam pipeline.

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