DCS feed content control system and method based on periodic characteristics of reduction furnace

Abstract

The invention discloses a DCS feed content control system and method based on periodic characteristics of a reduction furnace. The core advantage is dynamic precise programmed control of DCS and TCS content, and the material flow proportion can be automatically adjusted according to different periods such as a silicon rod nucleating period, a rapid growth period and a later deposition period, so that the polycrystalline silicon rod is more uniform in structure, fewer in defect and higher in purity, and the product quality consistency and grade rate are remarkably improved. The DCS / TCS pipeline flow closed-loop adjusting assembly dynamically matches the cycle matching requirement, 1.0 MPa steam heating and heat exchanger accurate temperature control are achieved, and the process abnormity caused by temperature fluctuation is reduced. The steam utilization rate and the condensate water recovery rate are greatly improved; the replacement process reduces material residues, raffinate is directionally recycled, and the raw material utilization rate is improved. The risk is thoroughly eliminated through nitrogen-hydrogen double replacement, harmful gas is discharged after reaching the standard through VG3 leaching, residual liquid is treated in real time, and the accident risk is reduced. The system supports parallel multi-group equipment and central control cooperative adjustment, and flexibly adapts to capacity expansion.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of reducing furnace production of high-purity silicon, and particularly relates to a DCS feeding content control system and method based on cycle characteristics of a reducing furnace. BACKGROUND

[0002] The reducing furnace is the core equipment for producing high-purity silicon by the improved Siemens process, and its running state directly determines the yield, quality and energy consumption of the high-purity silicon. How to ensure the reducing furnace to run in the best state has always been the most important technical pursuit goal of all polysilicon production enterprises.

[0003] In the process, SiH2Cl2 (referred to as DCS) is a by-product of the reaction of the reducing furnace and the cold hydrogenation furnace. Compared with the core raw material SiHCl3 (referred to as TCS), the number of Si-H bonds in the DCS molecule is more, and the chemical activity is more active. The reduction reaction (SiH2Cl2+H2→Si+2HCl) rate is faster than that of TCS (SiHCl3+H2→Si+3HCl), and it can react quickly at low temperature, and the generation amount is about 4.0-4.5% of TCS. The TCS reduction reaction needs high temperature to drive.

[0004] Because the chemical property of DCS is much more active than that of TCS, the content of DCS in the TCS feeding of the reducing furnace has a great influence on the production of the reducing furnace. When the content is high, although it is beneficial to improve the deposition speed in the early stage of the production of the reducing furnace, it is not conducive to the abnormal control such as atomization in the middle and late stages of the production of the reducing furnace. On the contrary, when the content is low, although it is beneficial to the abnormal control such as atomization in the middle and late stages of the production of the reducing furnace, it will significantly reduce the deposition speed in the early stage of the production of the reducing furnace. It can be said that both methods cannot perfectly adapt to the production of the reducing furnace. The content of DCS in the TCS feeding of the reducing furnace should be relatively high in the early stage of the production of the reducing furnace, and gradually reduced or even zero in the middle and late stages of the production of the reducing furnace.

[0005] At present, the domestic industry generally adopts fixed content control, and some enterprises also need to convert the excess DCS into TCS through reverse disproportionation reaction. At the same time, the domestic reducing furnace is developing towards larger and higher direction, and 5 million tons, 10 million tons and 20 million tons of devices mostly adopt 40 pairs and 60 pairs of furnace type. This trend not only improves the operation index, but also increases the difficulty of production control. At present, the polysilicon industry is in a trough stage of serious excess capacity, continuous cash loss and cruel reshuffle, and improving the operation index of the reducing furnace has important practical significance for the survival and development of enterprises.

[0006] The current industry general practice is to mix DCS into high-purity TCS in a fixed ratio in the rectification process and then send it to the reduction process, resulting in all reduction furnaces using the same DCS ratio of raw material TCS at different production times (production sequencing), which cannot meet the needs of different reduction furnaces at different production stages, directly limiting the improvement of the operation level of the reduction furnace. In addition, the risk of this technology is that there is no reference data for the mixing ratio of 40 pairs and 60 pairs of mainstream reduction furnace feed TCS and DCS, and a large number of process control parameters need to be explored during trial production. Since the reduction furnace production needs to match the TCS and DCS ratio at different time periods within 100 hours, as well as the corresponding current and hydrogen consumption, it may take a long time to reach the expected operating state. At present, it is an urgent problem to be solved to continuously optimize various operating parameters of the two types of reduction furnaces by using the reduction furnace intelligent control system. SUMMARY

[0007] Based on the above technical problems that the DCS content in the reduction furnace feed TCS is fixed throughout the production cycle and cannot adapt to the needs of different stages, the technical problem to be solved by the present application is to provide a DCS feed content control system and method based on the cycle characteristics of the reduction furnace, which further improves the power consumption, furnace production, conversion rate, silicon material quality and other indicators of the reduction furnace operation by controlling the appropriate feed DCS content at different production times of the reduction furnace.

[0008] The present application protects a DCS feed content control system based on the cycle characteristics of the reduction furnace, which comprises a rectification zone, a steam heating system, a reduction furnace feed heat exchanger and a reduction furnace mixer. The rectification zone comprises a DCS rectification pipeline, a TCS rectification pipeline and a flow regulating assembly and a filter matched with the pipeline, and the DCS rectification pipe and the TCS rectification pipe are respectively connected with the reduction furnace feed heat exchanger; for conveying the rectified DCS material and TCS material to the reduction furnace feed heat exchanger; the TCS rectification pipe is connected with a nitrogen N7 inlet pipeline and a matched valve; The steam heating system is a steam main and a pressure regulating assembly matched with the steam main, and the steam main is connected with the reduction furnace feed heat exchanger; for heating the DCS and TCS materials; The top end of the reduction furnace feed heat exchanger is connected with a reduction furnace mixer through a pipeline, and the pipeline leads out a VG3 elution pipeline; the reduction furnace mixer is connected with a reduction furnace through a hydrogen gas self-recycling pipeline and a hydrogen gas pipeline at the top of the reduction furnace mixer, which is used for replacing nitrogen with hydrogen after nitrogen replacement before system operation; the reduction furnace mixer is connected with the reduction furnace; the reduction furnace feed heat exchanger is connected with a flash tank through a steam condensation pipeline; and the reduction furnace feed heat exchanger is connected with a distillation 803 pipeline.

[0009] Further, the nitrogen N7 pipeline is connected to 0.7 MPa nitrogen N7; the system is used for purging and replacing the TCS material pipeline before operation, and air is excluded.

[0010] Further, when the gas containing trichloro dichloro is excluded from the reducing furnace feed heat exchanger after the nitrogen N7 purging and replacement in the system, the replacement gas is subjected to a washing treatment VG3.

[0011] Further, a pressure regulating circuit is further arranged on the steam condensing pipe, which is used for conveying condensate, low-pressure steam and the like in the system to a flash tank for gas-liquid separation.

[0012] Further, the residual liquid distillation 803 pipeline is used for conveying the residual liquid generated in the system during operation to a residual liquid treatment unit 803, so as to avoid the influence of residual liquid accumulation on reaction efficiency and equipment safety.

[0013] Further, the pressure of the steam main pipe is 1.0 MPa; and the pressure of the steam condensing pipe connected to the flash tank is 0.4 MPa.

[0014] Further, the system pressure regulating assembly comprises a pressure transmitter and a regulating valve; the flow regulating assembly comprises a flow transmitter, a manual switch and a regulating valve; a filter is arranged on the VG3 washing pipeline; and a steam anti-backflow assembly is arranged on the steam condensing pipeline.

[0015] Further, the number of the reducing furnace feed heat exchanger and the mixer thereof in the system can be multiple, and the specific connection relationship is the same as that of the single reducing furnace feed heat exchanger and the mixer thereof.

[0016] The application also protects the method of the above-mentioned DCS feed content control system based on the periodic characteristics of the reducing furnace, which specifically comprises the following steps: Step 1, system operation preparation Step 1.1, Equipment and Pipeline Verification: A comprehensive inspection and verification is conducted, including the integrity and functionality verification of the DCS distillation pipeline, TCS distillation pipeline, and their associated flow control components and filters in the distillation area. This ensures accurate flow sensor data, sensitive control valve operation, and undamaged filter screens. Simultaneously, the sealing of the nitrogen (N7) inlet pipe on the TCS distillation line and the valve's on / off status are checked. The pressure holding test is conducted at 0.8 MPa, with a pressure drop ≤ 0.02 MPa after 30 minutes. The 1.0 MPa steam main and pressure control components of the steam heating system are calibrated to verify the pressure transmitter's range and accuracy, and the control valve's pressure response is tested. The response speed is ensured to maintain a stable steam pressure of 1.0 MPa; the cleanliness and sealing performance of the heat exchange surface of the reduction furnace feed heat exchanger are checked; the sealing performance of the hydrogen self-recovery pipeline interface of the reduction furnace mixer is checked, as well as the on / off status and opening accuracy of the matching valves, the connection pipeline from its top to the reduction furnace mixer and the VG3 scrubbing pipeline, the 0.4 MPa steam condensation pipeline and the residual liquid to distillation 803 pipeline are checked; the integrity of the pressure regulating circuit, anti-backflow components and filter on the VG3 scrubbing pipeline is confirmed; Step 1.2, Replacement and Auxiliary Preparation: Connect a 0.7MPa nitrogen (N7) gas source to the TCS distillation tube, ensuring nitrogen purity ≥99.9%; connect a fresh hydrogen pipeline to the reduction furnace mixer, ensuring hydrogen purity ≥99.99% and pressure stable at 0.8-1.0MPa; check the pressure status of the hydrogen self-recovery pipeline, ensuring the recovered hydrogen pressure ≥0.6MPa is usable; check the valve status of the nitrogen delivery path, ensuring only the TCS distillation pipeline and the subsequent connected reduction furnace feed heat exchanger are in purging-ready passages, and all other unrelated pipeline valves are closed; confirm the VG3 rinsing system is in standby mode, and rinsing can be started immediately when the replacement gas contains harmful components such as trichlorodichloro. Step 2, system purging and replacement Step 2.1, Nitrogen purging and replacement: Close all material feed valves, hydrogen valves, and residual liquid discharge valves. Only open the nitrogen inlet valve of the TCS distillation tube and the valve from the reduction furnace feed heat exchanger to the VG3 scrubbing pipeline to form a purging path of nitrogen input-heat exchanger-scrubbing discharge. Slowly open the nitrogen valve to introduce nitrogen at a pressure of 0.7 MPa, controlling the purging flow rate to 30% of the pipeline's rated flow rate. After purging for 15 minutes, take a sample at the inlet of the VG3 scrubbing system to test the oxygen content. When the oxygen content... When the amount is ≤0.5%, switch the purging path: close the shower pipeline valve, open the valve from the heat exchanger to the reduction furnace mixer and the vent valve at the top of the mixer to form a path of nitrogen-TCS pipeline-heat exchanger-mixer-vent, and continue purging for 10 minutes; monitor the gas composition at the vent of the reduction furnace mixer in real time. If trichlorodichloro harmful components are detected, immediately switch to the VG3 shower path for discharge until the vent gas has no harmful components and the oxygen content is ≤0.3%, close the nitrogen valve, and complete the nitrogen replacement; Step 2.2, Hydrogen purging and replacement: Close the nitrogen valve and the mixer vent valve, open the fresh hydrogen pipeline valve of the reduction furnace mixer and the valve from the top of the mixer to the hydrogen self-recovery pipeline to form a replacement path of fresh hydrogen-mixer-hydrogen recovery; introduce fresh hydrogen at a pressure of 0.8 MPa, control the replacement flow rate to 1.5 times the mixer volume / hour, and continue replacement for 8 minutes. After that, take a sample at the mixer outlet to detect the nitrogen content. When the nitrogen content is ≤0.5%, close the fresh hydrogen valve and switch to the hydrogen self-recovery pipeline to maintain the pressure in the mixer at 0.3 MPa to complete the hydrogen replacement and prevent air from re-entering. Step 3, System preheating and material pre-transfer Step 3.1, Preheating the reduction furnace feed heat exchanger: Start the steam heating system, open the main steam valve, stabilize the steam pressure at 1.0 MPa using the pressure regulating component, and slowly introduce steam into the reduction furnace feed heat exchanger, controlling the heat exchanger heating rate at 5℃ / min until the preheating temperature of the material at the outlet of the reduction furnace feed heat exchanger reaches the process set value. The temperature transmitter provides real-time feedback to maintain a stable steam supply. During the preheating process, open the pressure regulating loop of the steam condensate pipeline to adjust the condensate and low-pressure steam pressure to 0.4 MPa, and transport them to the flash tank for gas-liquid separation. The separated gas phase is recovered to the steam pipeline network, and the liquid phase is discharged into the condensate recovery system.

[0017] Step 3.2, Material Pre-feeding and Proportioning Adjustment: Maintain the hydrogen pressure in the reduction furnace mixer at 0.3 MPa, slowly open the manual switch of the TCS distillation pipeline, and control the TCS material flow rate to 20% of the rated flow rate through the flow regulating component, feeding it to the reduction furnace feed heat exchanger. Observe the flow stability for 5 minutes. After the TCS flow rate stabilizes, open the DCS distillation pipeline valve. According to the initial feed ratio requirements of the reduction furnace, precisely control the DCS material flow rate through the flow regulating component. The two materials are initially mixed and heated in the reduction furnace feed heat exchanger. Through the feedback of the heat exchanger outlet temperature monitoring, fine-tune the steam supply to ensure that the temperature of the mixed material is stable within ±3℃ of the set value. Open the feed valve from the reduction furnace mixer to the reduction furnace, and feed the premixed material to the mixer at a low flow rate of 10% of the rated flow rate. After mixing with hydrogen, it is fed into the reduction furnace, completing the pre-feeding adjustment. Step 4, the system is running normally. Step 4.1, Precise Material Proportioning and Delivery: Based on the cyclical operation characteristics of the reduction furnace and the material ratio requirements of the DCS and TCS at different reaction stages, the feed flow rates of the two materials are adjusted in real time through the flow regulation components of the DCS and TCS pipelines in the rectification zone. This ensures that the material content entering the reduction furnace feed heat exchanger meets the process formulation requirements. After mixing and heating in the reduction furnace feed heat exchanger, the materials enter the reduction furnace mixer with hydrogen. The hydrogen consists of a thorough mixture of fresh and recovered hydrogen. The pressure inside the mixer is maintained at 0.2-0.4 MPa. The hydrogen supply is fine-tuned based on the concentration feedback at the mixer outlet to ensure a gas-liquid mixing uniformity ≥95%. During operation, if the system pressure exceeds the set value, the valve on the VG3 scrubbing pipeline automatically opens, diverting some gas to the scrubbing system. Simultaneously, the pressure of the flash tank is adjusted to maintain a stable system pressure of 0.4 MPa. Step 4.2, Steam Condensation and Residual Liquid Treatment: After heat exchange in the heat exchanger, the condensate temperature of the 1.0MPa steam drops to 80-90℃. After being reduced to 0.4MPa via a pressure regulating circuit, it is sent to the flash tank. The separated 0.4MPa low-pressure steam is used for preheating in the rectification zone. The condensate recovery rate is ≥90%, and the overall steam utilization rate is increased by 15%. The residual liquid discharge valve at the bottom of the reduction furnace feed heat exchanger is opened, and the residual liquid is continuously transported to the treatment unit at a pressure of 0.1MPa through the 803 pipeline. The transport flow rate is controlled at 2-5m³ / h. 3 / h, check pipeline pressure and flow rate every hour to avoid residual liquid accumulation and ensure that heat exchange efficiency is not affected.

[0018] Step 5, System Shutdown Procedure First, gradually reduce the feed flow rate of the DCS and TCS distillation pipelines by 10% / min until the feed valves are closed. Close the feed valve from the mixer to the reduction furnace, and open the valve from the mixer to the hydrogen self-recovery pipeline to recover residual hydrogen in the mixer until the pressure drops to 0.1 MPa. Then, close the main steam valve to stop the steam supply to the reduction furnace feed heat exchanger, and open the steam vent valve of the heat exchanger. After the heat exchanger temperature drops below 60°C and the pressure drops to 0 MPa, close the condensate delivery valve. Finally, first open the nitrogen (N7) inlet valve to purge the TCS and DCS pipelines and the reduction furnace feed heat exchanger with nitrogen at a pressure of 0.7 MPa and a flow rate of 30% of the rated value for 10 minutes to remove residual material. Then, open the fresh hydrogen pipeline valve to purge the reduction furnace mixer and the hydrogen pipeline at a pressure of 0.8 MPa and a flow rate of 50% of the rated value for 5 minutes to recover residual hydrogen, and then close all valves.

[0019] Furthermore, if the system is configured with multiple sets of reduction furnace feed heat exchangers and mixers, each set independently executes the above-mentioned material conveying, heating, and residual liquid treatment processes. At the same time, the central control system coordinates the DCS and TCS material ratios and steam supply of each set to ensure that the feed parameters of multiple reduction furnaces are synchronously matched with their cyclic operating characteristics.

[0020] Compared with existing technologies, the present invention has the following beneficial effects: This invention relates to a DCS feed content control system based on the cycle characteristics of a reduction furnace. By deeply coupling the feed ratio with the dynamic operating conditions of the reduction furnace, it brings significant systemic benefits. Its core advantage lies in achieving dynamic, precise, and programmed control of the DCS and TCS contents in the reduction furnace feed. It can automatically adjust the flow ratio of the two materials according to different growth cycles of silicon rods (such as the nucleation stage, rapid growth stage, and late deposition stage), thereby producing polycrystalline silicon rods with more uniform structure, fewer defects, and higher purity, greatly improving product quality consistency and grade yield.

[0021] In terms of process stability, relying on the DCS / TCS pipeline flow closed-loop regulation component, the feed ratio requirements of the reduction furnace in different cycles can be dynamically matched. Combined with 1.0MPa steam heating and precise temperature control of the heat exchanger, the process abnormalities caused by temperature fluctuations are effectively reduced, and the consistency of product batches is significantly improved. The configuration of filters and anti-backflow components reduces the risk of equipment blockage and wear, and extends the maintenance cycle.

[0022] In terms of energy consumption, steam adopts a cascade utilization mode. After heat exchange, the condensate is pressure-regulated to 0.4MPa and sent to the flash tank for separation. Low-pressure steam is recovered for distillation preheating, which improves the comprehensive utilization rate of steam and the condensate recovery rate. The nitrogen and hydrogen replacement process reduces material residue, and the residual liquid is recycled and treated in a targeted manner, which improves the utilization rate of raw materials.

[0023] In terms of safety and environmental protection, the nitrogen-hydrogen dual-replacement process completely eliminates air and nitrogen, avoiding the risk of mixing; harmful gases are scrubbed by VG3 to meet emission standards, and residual liquid is transported and treated in real time, significantly reducing the risk of accidents. The system has strong compatibility, supporting multiple heat exchangers and mixers in parallel, and can be flexibly adapted to capacity expansion needs and production lines of different sizes through central control and coordinated adjustment. Attached Figure Description

[0024] Figure 1 This is a flowchart of the overall system of the present invention; Figure 2 This is a detailed process flow diagram of the system of the present invention. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1 A DCS feed content control system based on the cycle characteristics of a reduction furnace includes a rectification zone, a steam heating system, a reduction furnace feed heat exchanger, and a reduction furnace mixer. The rectification zone includes a DCS rectification pipeline, a TCS rectification pipeline, and matching flow control components and filters. The DCS and TCS rectification pipelines are connected to the reduction furnace feed heat exchanger, respectively. This system is used to transport the distilled DCS and TCS materials to the reduction furnace feed heat exchanger. The TCS rectification pipeline is connected to a nitrogen (N7) inlet pipeline and matching valves. The steam heating system consists of a 1.0 MPa steam main and matching pressure control components, which are connected to the reduction furnace feed heat exchanger. This system is used to control the DCS and TCS materials. The feed heat exchanger of the reduction furnace has a top-end pipeline connected to the reduction furnace mixer, which leads to the VG3 scrubbing pipeline. A hydrogen self-recovery pipeline is introduced at the top of the reduction furnace mixer for replacing nitrogen with hydrogen after nitrogen purging before system operation. The reduction furnace mixer is connected to the reduction furnace. A steam condensation pipeline from the reduction furnace feed heat exchanger connects to a 0.4MPa flash tank. A pressure regulating circuit is also installed on the steam condensation pipeline to transport condensate and low-pressure steam from the system to the flash tank for gas-liquid separation. A residual liquid pipeline from the reduction furnace feed heat exchanger leads to the 803 distillation unit to transport residual liquid generated during system operation to the 803 residual liquid treatment unit, preventing residual liquid accumulation from affecting reaction efficiency and equipment safety.

[0027] The distillation zone includes a DCS distillation pipeline, a TCS distillation pipeline, and flow regulation components and filters for the pipelines. The DCS distillation pipeline and the TCS distillation pipeline are respectively connected to the feed heat exchanger of the reduction furnace. They are used to transport the distilled DCS and TCS materials to the feed heat exchanger of the reduction furnace. The TCS distillation pipeline is connected to a nitrogen (N7) inlet pipeline and a matching valve. The steam heating system consists of a steam main pipe and a pressure regulating component for the steam main pipe. The steam main pipe is connected to the feed heat exchanger of the reduction furnace and is used to heat DCS and TCS materials. The top of the reduction furnace feed heat exchanger leads to the reduction furnace mixer, and the pipeline leads to the VG3 scrubbing pipeline; the top of the reduction furnace mixer introduces a hydrogen self-recovery pipeline, and the reduction furnace mixer is connected to the reduction furnace; the steam condensation pipeline leading out of the reduction furnace feed heat exchanger is connected to the flash tank; the residual liquid leading out of the reduction furnace feed heat exchanger goes to the 803 distillation pipeline.

[0028] Before the system is put into operation, nitrogen gas (N7) at 0.7 MPa is introduced into the pipeline to purge and replace the TCS material pipeline and remove air. After the nitrogen gas is purged and replaced in the system, if the gas discharged from the reduction furnace feed heat exchanger contains trichlorodichloro, the replacement gas must be rinsed with VG3.

[0029] The system pressure regulating components include a pressure transmitter and a regulating valve; the flow regulating components include a flow transmitter, a manual switch, and a regulating valve; a filter is provided on the VG3 rinse line; and a steam backflow prevention component is provided on the steam condensation line.

[0030] Example 2 A method for a DCS feed content control system based on the cycle characteristics of a reduction furnace, specifically including the following steps: Step 1, Preparations before system operation Step 1.1, Equipment and Pipeline Verification: A comprehensive inspection and verification is conducted, including the integrity and functionality verification of the DCS distillation pipeline, TCS distillation pipeline, and their associated flow control components and filters in the distillation area. This ensures accurate flow sensor data, sensitive control valve operation, and undamaged filter screens. Simultaneously, the sealing of the nitrogen (N7) inlet pipe on the TCS distillation line and the valve's on / off status are checked. The pressure holding test is conducted at 0.8 MPa, with a pressure drop ≤ 0.02 MPa after 30 minutes. The 1.0 MPa steam main and pressure control components of the steam heating system are calibrated to verify the pressure transmitter's range and accuracy, and the control valve's pressure response is tested. The response speed is ensured to maintain a stable steam pressure of 1.0 MPa; the cleanliness and sealing performance of the heat exchange surface of the reduction furnace feed heat exchanger are checked; the sealing performance of the hydrogen self-recovery pipeline interface of the reduction furnace mixer is checked, as well as the on / off status and opening accuracy of the matching valves, the connection pipeline from its top to the reduction furnace mixer and the VG3 scrubbing pipeline, the 0.4 MPa steam condensation pipeline and the residual liquid to distillation 803 pipeline are checked; the integrity of the pressure regulating circuit, anti-backflow components and filter on the VG3 scrubbing pipeline is confirmed; Step 1.2, Replacement and Auxiliary Preparation: Connect a 0.7MPa nitrogen (N7) gas source to the TCS distillation tube, ensuring nitrogen purity ≥99.9%; connect a fresh hydrogen pipeline to the reduction furnace mixer, ensuring hydrogen purity ≥99.99% and pressure stable at 0.8-1.0MPa; check the pressure status of the hydrogen self-recovery pipeline, ensuring the recovered hydrogen pressure ≥0.6MPa is usable; check the valve status of the nitrogen delivery path, ensuring only the TCS distillation pipeline and the subsequent connected reduction furnace feed heat exchanger are in purging-ready passages, and all other unrelated pipeline valves are closed; confirm the VG3 rinsing system is in standby mode, and rinsing can be started immediately when the replacement gas contains harmful components such as trichlorodichloro. Step 2, system purging and replacement Step 2.1, Nitrogen purging and replacement: Close all material feed valves, hydrogen valves, and residual liquid discharge valves. Only open the nitrogen inlet valve of the TCS distillation tube and the valve from the reduction furnace feed heat exchanger to the VG3 scrubbing pipeline to form a purging path of nitrogen input-heat exchanger-scrubbing discharge. Slowly open the nitrogen valve to introduce nitrogen at a pressure of 0.7 MPa, controlling the purging flow rate to 30% of the pipeline's rated flow rate. After purging for 15 minutes, take a sample at the inlet of the VG3 scrubbing system to test the oxygen content. When the oxygen content... When the amount is ≤0.5%, switch the purging path: close the shower pipeline valve, open the valve from the heat exchanger to the reduction furnace mixer and the vent valve at the top of the mixer to form a path of nitrogen-TCS pipeline-heat exchanger-mixer-vent, and continue purging for 10 minutes; monitor the gas composition at the vent of the reduction furnace mixer in real time. If trichlorodichloro harmful components are detected, immediately switch to the VG3 shower path for discharge until the vent gas has no harmful components and the oxygen content is ≤0.3%, close the nitrogen valve, and complete the nitrogen replacement; Step 2.2, Hydrogen purging and replacement: Close the nitrogen valve and the mixer vent valve, open the fresh hydrogen pipeline valve of the reduction furnace mixer and the valve from the top of the mixer to the hydrogen self-recovery pipeline to form a replacement path of fresh hydrogen-mixer-hydrogen recovery; introduce fresh hydrogen at a pressure of 0.8 MPa, control the replacement flow rate to 1.5 times the mixer volume / hour, and continue replacement for 8 minutes. After that, take a sample at the mixer outlet to detect the nitrogen content. When the nitrogen content is ≤0.5%, close the fresh hydrogen valve and switch to the hydrogen self-recovery pipeline to maintain the pressure in the mixer at 0.3 MPa to complete the hydrogen replacement and prevent air from re-entering. Step 3, System preheating and material pre-transfer Step 3.1, Preheating the reduction furnace feed heat exchanger: Start the steam heating system, open the main steam valve, stabilize the steam pressure at 1.0 MPa using the pressure regulating component, and slowly introduce steam into the reduction furnace feed heat exchanger, controlling the heat exchanger heating rate at 5℃ / min until the preheating temperature of the material at the outlet of the reduction furnace feed heat exchanger reaches the process set value. The temperature transmitter provides real-time feedback to maintain a stable steam supply. During the preheating process, open the pressure regulating loop of the steam condensate pipeline to adjust the condensate and low-pressure steam pressure to 0.4 MPa, and transport them to the flash tank for gas-liquid separation. The separated gas phase is recovered to the steam pipeline network, and the liquid phase is discharged into the condensate recovery system.

[0031] Step 3.2, Material Pre-feeding and Proportioning Adjustment: Maintain the hydrogen pressure in the reduction furnace mixer at 0.3 MPa, slowly open the manual switch of the TCS distillation pipeline, and control the TCS material flow rate to 20% of the rated flow rate through the flow regulating component, feeding it to the reduction furnace feed heat exchanger. Observe the flow stability for 5 minutes. After the TCS flow rate stabilizes, open the DCS distillation pipeline valve. According to the initial feed ratio requirements of the reduction furnace, precisely control the DCS material flow rate through the flow regulating component. The two materials are initially mixed and heated in the reduction furnace feed heat exchanger. Through the feedback of the heat exchanger outlet temperature monitoring, fine-tune the steam supply to ensure that the temperature of the mixed material is stable within ±3℃ of the set value. Open the feed valve from the reduction furnace mixer to the reduction furnace, and feed the premixed material to the mixer at a low flow rate of 10% of the rated flow rate. After mixing with hydrogen, it is fed into the reduction furnace, completing the pre-feeding adjustment. Step 4, the system is running normally. Step 4.1, Precise Material Proportioning and Delivery: Based on the cyclical operation characteristics of the reduction furnace and the material ratio requirements of the DCS and TCS at different reaction stages, the feed flow rates of the two materials are adjusted in real time through the flow regulation components of the DCS and TCS pipelines in the rectification zone. This ensures that the material content entering the reduction furnace feed heat exchanger meets the process formulation requirements. After mixing and heating in the reduction furnace feed heat exchanger, the materials enter the reduction furnace mixer with hydrogen. The hydrogen consists of a thorough mixture of fresh and recovered hydrogen. The pressure inside the mixer is maintained at 0.2-0.4 MPa. The hydrogen supply is fine-tuned based on the concentration feedback at the mixer outlet to ensure a gas-liquid mixing uniformity ≥95%. During operation, if the system pressure exceeds the set value, the valve on the VG3 scrubbing pipeline automatically opens, diverting some gas to the scrubbing system. Simultaneously, the pressure of the flash tank is adjusted to maintain a stable system pressure of 0.4 MPa. Step 4.2, Steam Condensation and Residual Liquid Treatment: After heat exchange in the heat exchanger, the condensate temperature of the 1.0MPa steam drops to 80-90℃. After being reduced to 0.4MPa via a pressure regulating circuit, it is sent to the flash tank. The separated 0.4MPa low-pressure steam is used for preheating in the rectification zone. The condensate recovery rate is ≥90%, and the overall steam utilization rate is increased by 15%. The residual liquid discharge valve at the bottom of the reduction furnace feed heat exchanger is opened, and the residual liquid is continuously transported to the treatment unit at a pressure of 0.1MPa through the 803 pipeline. The transport flow rate is controlled at 2-5m³ / h. 3 / h, check pipeline pressure and flow rate every hour to avoid residual liquid accumulation and ensure that heat exchange efficiency is not affected.

[0032] Step 5, System Shutdown Procedure First, gradually reduce the feed flow rate of the DCS and TCS distillation pipelines by 10% / min until the feed valves are closed. Close the feed valve from the mixer to the reduction furnace, and open the valve from the mixer to the hydrogen self-recovery pipeline to recover residual hydrogen in the mixer until the pressure drops to 0.1 MPa. Then, close the main steam valve to stop the steam supply to the reduction furnace feed heat exchanger, and open the steam vent valve of the heat exchanger. After the heat exchanger temperature drops below 60°C and the pressure drops to 0 MPa, close the condensate delivery valve. Finally, first open the nitrogen (N7) inlet valve to purge the TCS and DCS pipelines and the reduction furnace feed heat exchanger with nitrogen at a pressure of 0.7 MPa and a flow rate of 30% of the rated value for 10 minutes to remove residual material. Then, open the fresh hydrogen pipeline valve to purge the reduction furnace mixer and the hydrogen pipeline at a pressure of 0.8 MPa and a flow rate of 50% of the rated value for 5 minutes to recover residual hydrogen, and then close all valves.

[0033] Example 3 If the system is configured with multiple sets of reduction furnace feed heat exchangers and mixers, the specific connection relationship is the same as that of a single reduction furnace feed heat exchanger and its mixer. Each set independently executes the material conveying, heating, and residual liquid treatment process. At the same time, the central control system coordinates the DCS and TCS material ratio and steam supply of each set to ensure that the feed parameters of multiple reduction furnaces are synchronously matched with their cycle operation characteristics.

[0034] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A DCS feed content control system based on the cycle characteristics of a reduction furnace, characterized in that, This includes the distillation zone, steam heating system, reduction furnace feed heat exchanger, reduction furnace mixer, and reduction furnace; The distillation zone includes a DCS distillation pipeline, a TCS distillation pipeline, and flow regulation components and filters for the pipelines. The DCS distillation pipeline and the TCS distillation pipeline are respectively connected to the feed heat exchanger of the reduction furnace. They are used to transport the distilled DCS and TCS materials to the feed heat exchanger of the reduction furnace. The TCS distillation pipeline is connected to a nitrogen (N7) inlet pipeline and a matching valve. The steam heating system consists of a steam main pipe and a pressure regulating component for the steam main pipe. The steam main pipe is connected to the feed heat exchanger of the reduction furnace and is used to heat DCS and TCS materials. The top of the reduction furnace feed heat exchanger leads to the reduction furnace mixer, and the pipeline leads to the VG3 scrubbing pipeline; the top of the reduction furnace mixer introduces a hydrogen self-recovery pipeline, and the reduction furnace mixer is connected to the reduction furnace; the steam condensation pipeline leading out of the reduction furnace feed heat exchanger is connected to the flash tank; the residual liquid leading out of the reduction furnace feed heat exchanger goes to the 803 distillation pipeline.

2. The DCS feed content control system based on the cycle characteristics of a reduction furnace according to claim 1, characterized in that, The nitrogen N7 inlet pipeline is supplied with 0.7MPa nitrogen N7; this is used to purge and replace air from the TCS material pipeline before the system is put into operation.

3. The DCS feed content control system based on the cycle characteristics of a reduction furnace according to claim 2, characterized in that, After nitrogen (N7) purging and replacement in the system, if the gas discharged from the feed heat exchanger of the reduction furnace contains trichlorodichloro, the replacement gas must be subjected to a VG3 scrubbing treatment.

4. The DCS feed content control system based on the cycle characteristics of a reduction furnace according to claim 1, characterized in that, The steam condenser pipe is also equipped with a pressure regulating circuit, which is used to transport the condensate and low-pressure steam in the system to the flash tank for gas-liquid separation.

5. A DCS feed content control system based on the cycle characteristics of a reduction furnace according to claim 1, characterized in that, The residual liquid to distillation 803 pipeline is used to transport the residual liquid generated during system operation to the 803 residual liquid treatment unit to avoid the accumulation of residual liquid affecting reaction efficiency and equipment safety.

6. The DCS feed content control system based on the cycle characteristics of a reduction furnace according to claim 1, characterized in that, The pressure on the main steam pipe is 1.0 MPa; the pressure on the steam condenser connected to the flash tank is 0.4 MPa.

7. A DCS feed content control system based on the cycle characteristics of a reduction furnace according to claim 1, characterized in that, The system pressure regulating component includes a pressure transmitter and a regulating valve; the flow regulating component includes a flow transmitter, a manual switch and a regulating valve; a filter is provided on the VG3 rinse line; and a steam backflow prevention component is provided on the steam condensation line.

8. A DCS feed content control system based on the cycle characteristics of a reduction furnace according to claim 1, characterized in that, The system can have multiple reduction furnace feed heat exchangers and their mixers, and the specific connection relationship is the same as that of a single reduction furnace feed heat exchanger and its mixer.

9. A method for a DCS feed content control system based on the periodic characteristics of a reduction furnace according to any one of claims 1-8, characterized in that, Specifically, the steps include the following: Step 1, Preparations before system operation Step 1.1, Equipment and Piping Verification: Comprehensive inspection and verification, including the DCS in the distillation area. The integrity and functionality of the distillation pipeline, TCS distillation pipeline, and associated flow control components and filters were verified to ensure accurate flow sensor data, sensitive control valve operation, and undamaged filter screens. Simultaneously, the sealing of the nitrogen (N7) inlet pipe on the TCS distillation pipeline and the valve's on / off status were checked. The 1.0MPa steam main and pressure control components of the steam heating system were calibrated to verify the range and accuracy of the pressure transmitter, and the response speed of the control valve to pressure was tested to ensure a stable 1.0MPa steam pressure. The cleanliness and sealing performance of the heat exchange surface of the reduction furnace feed heat exchanger were checked. The sealing of the hydrogen self-recovery pipeline interface of the reduction furnace mixer was verified, along with the on / off status and opening accuracy of the associated valves, as well as the unobstructed flow of the connecting pipeline from its top to the reduction furnace mixer, the VG3 rinsing pipeline, the 0.4MPa steam condensation pipeline, and the residual liquid to distillation 803 pipeline. The integrity of the pressure regulating circuit, anti-backflow components, and filters on the VG3 rinsing pipeline on the steam condensation pipe was confirmed. Step 1.2, Replacement and Auxiliary Preparation: Connect a 0.7MPa nitrogen (N7) gas source to the TCS distillation tube; connect a fresh hydrogen pipeline to the reduction furnace mixer, stabilizing the pressure at 0.8-1.0MPa; check the pressure status of the hydrogen self-recovery pipeline to ensure that the recovered hydrogen pressure is ≥0.6MPa for normal use; check the valve status of the nitrogen delivery path to ensure that only the TCS distillation pipeline and the subsequent connected reduction furnace feed heat exchanger are in purging-ready passages, and all other unrelated pipeline valves are closed; confirm that the VG3 rinsing system is in standby mode, and rinsing can be started immediately when the replacement gas contains harmful components such as trichlorodichloro. Step 2, system purging and replacement Step 2.1, Nitrogen purging and replacement: Close all material feed valves, hydrogen valves, and residual liquid discharge valves. Only open the nitrogen inlet valve of the TCS distillation tube and the valve from the reduction furnace feed heat exchanger to the VG3 scrubbing pipeline to form a purging path of nitrogen input-heat exchanger-scrubbing discharge. Slowly open the nitrogen valve to introduce nitrogen, controlling the purging flow rate to 30% of the pipeline's rated flow rate. After purging for 15 minutes, take a sample at the inlet of the VG3 scrubbing system to test the oxygen content. When the oxygen content is ≤0. At 5%, switch the purging path: close the scrubbing pipeline valve, open the valve from the heat exchanger to the reduction furnace mixer and the vent valve at the top of the mixer to form a path of nitrogen-TCS pipeline-heat exchanger-mixer-vent, and continue purging for 10 minutes; monitor the gas composition at the vent of the reduction furnace mixer in real time. If trichlorodichloro harmful components are detected, immediately switch to the VG3 scrubbing path for discharge until the vent gas has no harmful components and the oxygen content is ≤0.3%. Then close the nitrogen valve to complete the nitrogen replacement. Step 2.2, Hydrogen purging and replacement: Close the nitrogen valve and the mixer vent valve, open the fresh hydrogen pipeline valve of the reduction furnace mixer and the valve from the top of the mixer to the hydrogen self-recovery pipeline to form a replacement path of fresh hydrogen-mixer-hydrogen recovery; introduce fresh hydrogen at a pressure of 0.8 MPa, control the replacement flow rate to 1.5 times the mixer volume / hour, and continue replacement for 8 minutes. After that, take a sample at the mixer outlet to detect the nitrogen content. When the nitrogen content is ≤0.5%, close the fresh hydrogen valve and switch to the hydrogen self-recovery pipeline to maintain the pressure in the mixer at 0.3 MPa to complete the hydrogen replacement and prevent air from re-entering. Step 3, System preheating and material pre-transfer Step 3.1, Preheating of the reduction furnace feed heat exchanger: Start the steam heating system, open the main steam valve, stabilize the steam pressure at 1.0 MPa using the pressure regulating component, and slowly introduce steam into the reduction furnace feed heat exchanger, controlling the heat exchanger heating rate at 5℃ / min until the preheating temperature of the material at the outlet of the reduction furnace feed heat exchanger reaches the process set value. The temperature transmitter provides real-time feedback to maintain a stable steam supply. During the preheating process, open the pressure regulating loop of the steam condensate pipeline to adjust the condensate and low-pressure steam pressure to 0.4 MPa, and transport them to the flash tank for gas-liquid separation. The separated gas phase is recovered to the steam pipeline network, and the liquid phase is discharged into the condensate recovery system. Step 3.2, Material Pre-feeding and Proportioning Adjustment: Maintain the hydrogen pressure in the reduction furnace mixer at 0.3 MPa, slowly open the manual switch of the TCS distillation pipeline, and control the TCS material flow rate to 20% of the rated flow rate through the flow regulating component, feeding it to the reduction furnace feed heat exchanger. Observe the flow stability for 5 minutes. After the TCS flow rate stabilizes, open the DCS distillation pipeline valve. According to the initial feed ratio requirements of the reduction furnace, precisely control the DCS material flow rate through the flow regulating component. The two materials are initially mixed and heated in the reduction furnace feed heat exchanger. Through the feedback of the heat exchanger outlet temperature monitoring, fine-tune the steam supply to ensure that the temperature of the mixed material is stable within ±3℃ of the set value. Open the feed valve from the reduction furnace mixer to the reduction furnace, and feed the premixed material to the mixer at a low flow rate of 10% of the rated flow rate. After mixing with hydrogen, it is fed into the reduction furnace, completing the pre-feeding adjustment. Step 4, the system is running normally. Step 4.1, Precise Material Proportioning and Delivery: Based on the cyclical operation characteristics of the reduction furnace and the material ratio requirements of the DCS and TCS at different reaction stages, the feed flow rates of the two materials are adjusted in real time through the flow regulation components of the DCS and TCS pipelines in the rectification zone. This ensures that the material content entering the reduction furnace feed heat exchanger meets the process formulation requirements. After mixing and heating in the reduction furnace feed heat exchanger, the materials enter the reduction furnace mixer with hydrogen. The hydrogen consists of a thorough mixture of fresh and recovered hydrogen. The pressure inside the mixer is maintained at 0.2-0.4 MPa. The hydrogen supply is fine-tuned based on the concentration feedback at the mixer outlet to ensure a gas-liquid mixing uniformity ≥95%. During operation, if the system pressure exceeds the set value, the valve on the VG3 scrubbing pipeline automatically opens, diverting some gas to the scrubbing system. Simultaneously, the pressure of the flash tank is adjusted to maintain a stable system pressure of 0.4 MPa. Step 4.2, Steam Condensation and Residual Liquid Treatment: After heat exchange in the heat exchanger, the condensate temperature of the 1.0MPa steam drops to 80-90℃. After being reduced to 0.4MPa via a pressure regulating circuit, it is sent to the flash tank. The separated 0.4MPa low-pressure steam is used for preheating in the rectification zone. The condensate recovery rate is ≥90%, and the overall steam utilization rate is increased by 15%. The residual liquid discharge valve at the bottom of the reduction furnace feed heat exchanger is opened, and the residual liquid is continuously transported to the treatment unit at a pressure of 0.1MPa through the 803 pipeline. The transport flow rate is controlled at 2-5m³ / h. 3 / h, check pipeline pressure and flow rate every hour to avoid residual liquid accumulation and ensure that heat exchange efficiency is not affected; Step 5, System shutdown procedure First, gradually reduce the feed flow rate of the DCS and TCS distillation pipelines by 10% / min until the feed valves are closed. Close the feed valve from the mixer to the reduction furnace, and open the valve from the mixer to the hydrogen self-recovery pipeline to recover residual hydrogen in the mixer until the pressure drops to 0.1 MPa. Then, close the main steam valve to stop the steam supply to the reduction furnace feed heat exchanger, and open the steam vent valve of the heat exchanger. After the heat exchanger temperature drops below 60°C and the pressure drops to 0 MPa, close the condensate delivery valve. Finally, first open the nitrogen (N7) inlet valve to purge the TCS and DCS pipelines and the reduction furnace feed heat exchanger with nitrogen at a pressure of 0.7 MPa and a flow rate of 30% of the rated value for 10 minutes to remove residual material. Then, open the fresh hydrogen pipeline valve to purge the reduction furnace mixer and the hydrogen pipeline at a pressure of 0.8 MPa and a flow rate of 50% of the rated value for 5 minutes to recover residual hydrogen, and then close all valves.

10. The method according to claim 9, characterized in that, If the system is configured with multiple sets of reduction furnace feed heat exchangers and mixers, each set independently executes the above-mentioned material conveying, heating, and residual liquid treatment processes. At the same time, the central control system coordinates the DCS and TCS material ratios and steam supply of each set to ensure that the feed parameters of multiple reduction furnaces are synchronously matched with their cyclic operating characteristics.

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