A system for graded utilization of reducing section lye

Abstract

The utility model discloses a kind of reduction section lye grading utilization systems, it is related to the resource utilization technology field of lye in the reduction section of polysilicon production, including respectively for cleaning silicon nitride insulation ring, silicon nitride heat insulation piece and reduction furnace cylinder cleaning pool I, cleaning pool II and cleaning pool III, the liquid outlet I of cleaning pool I is connected the liquid inlet II of cleaning pool II by pipeline I, the liquid outlet II of cleaning pool II is connected the liquid inlet III of cleaning pool III by pipeline II, be equipped with liquid level meter I and pH meter I on the cleaning pool I, be equipped with liquid level meter II and pH meter II on cleaning pool II, be equipped with liquid level meter III on cleaning pool III, alkali inlet pipe is connected on the cleaning pool I, cleaning pool I, cleaning pool II and cleaning pool III are all connected with desalted water supply pipeline, valve is also equipped on pipeline, when the silicon nitride insulation ring, silicon nitride heat insulation piece, reduction furnace cylinder in the reduction section of polysilicon production are washed, there is the problem of great lye and water resource waste.

Description

Technical Field

[0001] This utility model relates to the field of resource utilization technology of alkaline solution in the reduction section of polysilicon production, and specifically to a graded utilization system for alkaline solution in the reduction section. Background Technology

[0002] In the reduction section of polysilicon production, after the reduction furnace is started, key components with attached silicon deposits need to be cleaned, mainly including silicon nitride insulating rings, silicon nitride heat insulation components, and the reduction furnace cylinder. Currently, the industry commonly uses an alkaline solution immersion method of a specific concentration for cleaning.

[0003] The test results show that the optimal alkaline solution concentrations required for the three types of components differ significantly to ensure cleaning effectiveness while avoiding damage to the component structure. Therefore, the current cleaning process typically involves manually preparing alkaline solutions of appropriate concentrations for different components and performing separate soaking and cleaning. After the cleaning operation is completed, the generated waste alkaline solution is directly discharged into a public auxiliary system for wastewater treatment.

[0004] However, this process has the following significant drawbacks: 1. Manual preparation and concentration maintenance rely on experience: Each cleaning operation requires the manual preparation of alkaline solutions of different concentrations. During the soaking process, the operator's experience is also required to add solid sodium hydroxide (caustic soda flakes) in a timely manner to maintain the required concentration. The operation is cumbersome and the accuracy is difficult to guarantee.

[0005] 2. Direct discharge of waste alkali solution leads to resource waste: Because the concentrations of alkali solutions used for cleaning different components vary and cannot be mixed, all waste alkali solutions, regardless of concentration, are directly treated as waste liquid after cleaning. This not only increases the waste liquid treatment load but also results in a large amount of underutilized alkali solution being wasted, failing to achieve effective resource recycling. Summary of the Invention

[0006] The purpose of this invention is to solve the problem of significant waste of alkali and water resources during the washing of silicon nitride insulating rings, silicon nitride heat insulation components, and reduction furnace cylinders in the reduction process of polysilicon production.

[0007] This utility model is achieved through the following technical solution: A graded utilization system for alkaline solution in a reduction process includes cleaning tank I, cleaning tank II, and cleaning tank III, which are used for cleaning silicon nitride insulating rings, silicon nitride heat insulation components, and reduction furnace cylinders, respectively. The drain outlet I of cleaning tank I is connected to the inlet II of cleaning tank II via pipe I, and the drain outlet II of cleaning tank II is connected to the inlet III of cleaning tank III via pipe II. The cleaning tank I is equipped with a level gauge I and a pH meter I, the cleaning tank II is equipped with a level gauge II and a pH meter II, the cleaning tank III is equipped with a level gauge III, the cleaning tank I is connected to an alkaline inlet pipe, and the cleaning tank I, the cleaning tank II and the cleaning tank III are respectively connected to a demineralized water supply line I, a demineralized water supply line II and a demineralized water supply line III. Valve I, valve II, valve III, valve IV, valve V, and valve VI are respectively installed on the alkali inlet pipe, pipeline I, pipeline II, demineralized water supply pipeline I, demineralized water supply pipeline II, and demineralized water supply pipeline III.

[0008] Furthermore, an alkali solution tank is connected to the front end of the alkali solution inlet pipe.

[0009] Furthermore, it also includes a controller, which is connected to level gauge I, pH meter I, level gauge II, pH meter III, valve I, valve II, valve III, valve IV, valve V and valve VI respectively.

[0010] Furthermore, a pH meter III is installed on the cleaning tank III.

[0011] Furthermore, the rear end of the cleaning tank II is connected to 2 to 5 cleaning tanks III via pipes.

[0012] Furthermore, multiple cleaning branch pipes are connected to the rear end of cleaning tank II via pipe II, and each cleaning branch pipe is connected to a cleaning tank III.

[0013] Furthermore, the bottoms of the cleaning tanks I, II, and III are funnel-shaped or downward-protruding arc-shaped structures, and the drain outlets I, II, and III of the cleaning tanks are all located at the bottom of the tanks.

[0014] Furthermore, filters are installed on both pipe I and pipe II.

[0015] Furthermore, the filter element is made of stainless steel and has a filtration accuracy of 10~80μm.

[0016] Furthermore, the rear end of cleaning tank III is connected to a wastewater treatment system via a pipeline.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects: I. This utility model proposes a graded utilization system for alkaline solutions in the reduction section. By studying the appropriate alkaline concentration for cleaning silicon nitride insulating rings, silicon nitride heat insulation components, and the reduction furnace shell, the system is designed to recycle and reuse the alkaline solution that still has usable value after use at the front end (e.g., high-concentration alkaline solution is required for cleaning silicon nitride insulating rings) for cleaning silicon nitride heat insulation components (medium-concentration alkaline solution is required for cleaning silicon nitride heat insulation components). At the same time, the concentration of the cleaning solution in cleaning tank II is detected by pH meter II, and an appropriate amount of demineralized water is added for dilution to obtain a second concentration (medium concentration) of alkaline solution. After consuming a certain amount of alkali (i.e., the concentration of the washing alkaline solution is further reduced), it is sent to cleaning tank III as the cleaning solution for the reduction furnace shell. If the concentration of the alkaline solution output from cleaning tank II is too high, an appropriate amount of demineralized water can be added to cleaning tank III through demineralized water supply pipeline III to prepare a cleaning solution of the preset concentration for cleaning the reduction furnace shell. This alkaline solution grading and utilization system solves the problems of low operating efficiency, insufficient precision, and the need for frequent manual preparation of alkaline solutions of various concentrations in traditional alkaline solution cleaning processes for silicon nitride insulating rings, silicon nitride heat insulation components, and reduction furnace cylinders, which are time-consuming and labor-intensive. Furthermore, this system allows for strict control of the alkaline solution concentration for each part being cleaned, ensuring its stability and consistent cleaning results. This reduces the likelihood of damage to components or incomplete cleaning due to improper operation. Simultaneously, the system maximizes the utilization of alkaline solutions used in the reduction process, reducing the generation of waste alkaline solutions, the consumption of caustic soda flakes, and the amount of demineralized water used, thereby lowering production costs.

[0018] II. In this utility model, the front end of the alkali inlet pipe is connected to an alkali tank, which is used to prepare a high-concentration alkali solution and to supply the high-concentration alkali solution to the cleaning tank I.

[0019] Third, this utility model also includes a controller, which can be a PLC or DCS. The controller is connected to level gauge I, pH meter I, level gauge II, pH meter III, valve I, valve II, valve III, valve IV, valve V and valve VI respectively, which facilitates automated production and ensures that the concentration of the alkaline solution used for cleaning silicon nitride insulating rings, silicon nitride heat insulation parts and reduction furnace cylinder in cleaning tank I, cleaning tank II and cleaning tank III is stable, and the concentration of the alkaline solution used for cleaning each batch of parts is consistent.

[0020] IV. In this utility model, a pH meter III is provided on the cleaning tank III to detect the alkali concentration of the cleaning solution in the cleaning tank III.

[0021] V. In this utility model, according to calculations, the amount of alkali solution in a single cleaning tank II, after being diluted to a preset concentration (the alkali solution concentration suitable for cleaning the cylinder of a reduction furnace), can be used to clean multiple cylinders of a reduction furnace. In order to improve production efficiency, multiple cleaning tanks III are connected to the rear end of cleaning tank II through pipes. It is generally advisable to design 2 to 5 cleaning tanks III.

[0022] VI. In this utility model, the rear end of the cleaning tank II is connected to multiple cleaning branch pipes via pipe II, and each cleaning branch pipe is connected to a cleaning tank III. Multiple cleaning branch pipes are connected through a drain port set on the cleaning tank II. On the one hand, the use of pipes can be reduced; on the other hand, each cleaning tank III can work relatively independently, which is convenient to meet different needs in actual working conditions.

[0023] VII. In this utility model, the bottom of the cleaning tank I, cleaning tank II, and cleaning tank III is a funnel-shaped structure or a downwardly protruding arc-shaped structure. The drain outlet I of cleaning tank I, the drain outlet II of cleaning tank II, and the drain outlet III of cleaning tank III are all located at the bottom of the tank. This facilitates the deposition of large particles of impurities generated during cleaning at the bottom of the tank, making them difficult to clean. The funnel-shaped structure or the downwardly protruding arc-shaped structure helps impurities to be discharged from the bottom of the tank. Preferably, a filter is provided at the drain outlet or on the connected pipe (near the drain outlet) to intercept most of the impurities and prevent impurities from circulating in the system, thus affecting the normal operation of the system.

[0024] 8. In this utility model, the filter element is made of stainless steel and has a filtration accuracy of 10~80μm, which can intercept most impurities.

[0025] 9. In this utility model, the rear end of the cleaning tank III is connected to the wastewater treatment system through a pipeline, which facilitates centralized treatment of the dilute alkali solution after cleaning the reduction furnace cylinder. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the alkaline solution classification and utilization system in the reduction section of this utility model. Figure 1 .

[0027] Figure 2 This is a schematic diagram of the alkaline solution classification and utilization system in the reduction section of this utility model. Figure 2 .

[0028] Figure 3 This is a schematic diagram of the alkaline solution classification and utilization system in the reduction section of this utility model. Figure 3 .

[0029] Figure 4 This is a schematic diagram of the alkaline solution classification and utilization system in the reduction section of this utility model. Figure 4 .

[0030] Figure 5 This is a schematic diagram of the structure of cleaning tank I.

[0031] Figure 6 This is a schematic diagram of another embodiment of the cleaning tank I.

[0032] Figure 7 This is a schematic diagram of the alkaline solution classification and utilization system in the reduction section of this utility model. Figure 5 .

[0033] Figure 8 This is a schematic diagram of the alkaline solution classification and utilization system in the reduction section of this utility model. Figure 6 .

[0034] The system includes: 1. Cleaning tank I; 2. Cleaning tank II; 3. Cleaning tank III; 4. Pipeline I; 5. Pipeline II; 6. Level gauge I; 7. pH meter I; 8. Level gauge II; 9. pH meter II; 10. Level gauge III; 11. Alkali inlet pipe; 12. Demineralized water supply line I; 13. Demineralized water supply line II; 14. Demineralized water supply line III; 15. Valve I; 16. Valve II; 17. Valve III; 18. Valve IV; 19. Valve V; 20. Valve VI; 21. Alkali tank; 22. Controller; 23. pH meter III; 24. Cleaning branch pipe; 25. Filter I; 26. Filter II; 27. Wastewater treatment system; 1.1. Drain outlet I; 2.1. Inlet II; 2.2. Drain outlet II; 3.1. Inlet III. Detailed Implementation The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0035] Example 1 A graded utilization system for alkali solution in a reduction process includes cleaning tank I1, cleaning tank II2, and cleaning tank III3, respectively used for cleaning silicon nitride insulating rings, silicon nitride heat insulation components, and the reduction furnace cylinder. (Reference) Figure 1 The drain outlet I1.1 of cleaning tank I1 is connected to the inlet II2.1 of cleaning tank II2 through pipe I4, and the drain outlet II2.2 of cleaning tank II2 is connected to the inlet III3.1 of cleaning tank III3 through pipe II5.

[0036] The cleaning tank I1 is equipped with a level gauge I6 and a pH meter I7, the cleaning tank II2 is equipped with a level gauge II8 and a pH meter II9, and the cleaning tank III3 is equipped with a level gauge III10. The cleaning tank I1 is connected to an alkaline inlet pipe 11. The cleaning tanks I1, II2 and III3 are respectively connected to a demineralized water supply pipeline I12, a demineralized water supply pipeline II13 and a demineralized water supply pipeline III14. Valves I15, II16, III17, IV18, V19, and VI20 are respectively installed on the alkali inlet pipe 11, pipe I4, pipe II5, demineralized water supply line I12, demineralized water supply line II13, and demineralized water supply line III14.

[0037] Based on the fact that silicon nitride insulating rings have the highest requirement for alkali concentration, followed by silicon nitride heat insulation components, and reduction furnace cleaning has the lowest requirements for alkali concentration and purity, the entire cleaning process only needs to maintain an alkali concentration higher than the minimum required concentration. However, in polysilicon production, the amount of alkali required for cleaning the entire reduction furnace cylinder is far greater than the sum of the alkali amounts required for the preceding systems (silicon nitride insulating ring cleaning and silicon nitride heat insulation component cleaning).

[0038] When the system is running, ① Concentration adjustment before cleaning: First, open valve I15, read the pH value of the cleaning solution in cleaning tank I1 through pH meter I7, and then calculate the alkali concentration. Calculate the dilution ratio based on the alkali concentration. When the dilution ratio * current liquid level is greater than the required minimum liquid level, close valve I15, open valve IV18 to replenish demineralized water until the current liquid level is greater than the required minimum liquid level, and then close valve IV18.

[0039] ② Concentration adjustment during the cleaning process: If the concentration of the alkali solution is lower than the optimal concentration during cleaning, the corresponding valve on the inlet pipe at the front end of the cleaning tank should be opened to draw alkali solution from the cleaning tank of the previous gradient to replenish the concentration. Once the set concentration is reached, the valve on the inlet pipe should be closed. If the liquid level exceeds the maximum set value at this time, the valve on the drain pipe should be opened to discharge the excess alkali solution to the next stage.

[0040] ③ Liquid level adjustment during the cleaning process: If the liquid level drops below the set value due to rapid consumption of downstream alkali solution, the corresponding valve on the inlet pipe at the front end of the cleaning tank must be opened first. The dilution ratio and the required minimum liquid level should be calculated in real time using a pH meter. When the product of the dilution ratio and the current liquid level is greater than the required minimum liquid level, the valve on the inlet pipe should be closed. Then, the valve on the demineralized water supply line should be opened. After the liquid level is replenished to the required minimum liquid level, the valve on the demineralized water supply line should be closed.

[0041] Example 2 This embodiment is a further optimization of embodiment 1, the difference being that an alkali solution tank 21 is connected to the front end of the alkali solution inlet pipe 11. (See reference...) Figure 2 .

[0042] Example 3 The difference between this embodiment and embodiments 1-2 is that it also includes a controller 22, see reference. Figure 2 The controller 22 is connected to the level gauge I6, pH meter I7, level gauge II8, pH meter II9, level gauge III10, valve I15, valve II16, valve III17, valve IV18, valve V19 and valve VI20 respectively.

[0043] Example 4 The difference between this embodiment and embodiments 1-3 is that the cleaning tank Ⅲ3 is equipped with a pH meter Ⅲ23 for reference. Figure 2pH meter Ⅲ23 is used to detect the pH value of the cleaning solution in cleaning tank Ⅲ3.

[0044] Example 5 Compared with Examples 1-4, the difference in this embodiment is that it is preferable to connect 2-5 cleaning tanks III3 to the rear end of the cleaning tank II2 via pipes. (Reference) Figure 3 , Figure 3 The illustration shows that the rear end of cleaning tank II2 is connected to four cleaning tanks III3 via pipelines. The instruments, connecting pipelines, and valves installed on each cleaning tank III3 are the same, and cleaning tank III3 can be selected to be used simultaneously or partially according to the actual working conditions.

[0045] Example 6 Compared with embodiments 1-5, the difference in this embodiment is that multiple cleaning branch pipes 24 are connected to the rear end of cleaning tank II2 via pipe II5, and each cleaning branch pipe 24 is connected to a cleaning tank III3. (Refer to...) Figure 4 This is beneficial for saving pipelines, and only one drain outlet needs to be designed on the cleaning tank II2.

[0046] Example 7 Compared with Examples 1-6, the difference in this embodiment is that the bottoms of cleaning tank I1, cleaning tank II2, and cleaning tank III3 are funnel-shaped or downwardly protruding arc-shaped structures, and the drain outlets I1.1 of cleaning tank I1, II2.2 of cleaning tank II2, and III of cleaning tank III3 are all located at the bottom of the tanks. (Reference) Figure 5 or Figure 6 , Figure 5 The illustration shows the arc-shaped cleaning tank I1. Figure 6 The illustration shows a funnel-shaped cleaning tank I1, which facilitates the discharge of impurities from the bottom drain outlet.

[0047] Example 8 Compared with Examples 1-7, the difference in this embodiment is that filter I25 and filter II26 are respectively installed on pipe I4 and pipe II5, respectively. (Refer to...) Figure 7 This facilitates the interception and timely removal of impurities washed off.

[0048] Preferably, the filter element is made of stainless steel and has a filtration accuracy of 10~80μm, which can intercept most of the impurities washed out.

[0049] Example 9 The difference between this embodiment and embodiments 1-8 is that the rear end of the cleaning tank Ⅲ3 is connected to the wastewater treatment system 27 via a pipe. (Refer to...) Figure 7 or Figure 8 .

[0050] Example 10 To facilitate public understanding of this solution, this embodiment uses a reduction section alkali solution classification and utilization system of our company as an example, and further explains it in conjunction with the accompanying drawings.

[0051] refer to Figure 8 The system includes cleaning tank I1, cleaning tank II2, and cleaning tank III3 for cleaning silicon nitride insulating rings, silicon nitride heat insulation components, and reduction furnace cylinders, respectively. The drain port I1.1 of cleaning tank I1 is connected to the inlet port II2.1 of cleaning tank II2 through pipe I4, and the drain port II2.2 of cleaning tank II2 is connected to the inlet port III3.1 of cleaning tank III3 through pipe II5.

[0052] The cleaning tank I1 is equipped with a level gauge I6 and a pH meter I7, the cleaning tank II2 is equipped with a level gauge II8 and a pH meter II9, and the cleaning tank III3 is equipped with a level gauge III10. The cleaning tank I1 is connected to an alkaline inlet pipe 11. The cleaning tanks I1, II2 and III3 are respectively connected to a demineralized water supply line I12, a demineralized water supply line II13 and a demineralized water supply line III14.

[0053] The alkaline inlet pipe 11, pipe I 4, pipe II 5, demineralized water supply line I 12, demineralized water supply line II 13 and demineralized water supply line III 14 are respectively equipped with valve I 15, valve II 16, valve III 17, valve IV 18, valve V 19 and valve VI 20. The front end of the alkaline inlet pipe 11 is connected to the alkaline tank 21.

[0054] In this embodiment, a controller 22 is also included, which is connected to the level gauge I6, pH meter I7, level gauge II8, pH meter II9, level gauge III10, valve I15, valve II16, valve III17, valve IV18, valve V19 and valve VI20 respectively.

[0055] In this embodiment, a pH meter III23 is installed on the cleaning tank III3.

[0056] In this embodiment, the rear end of the cleaning tank II2 is connected to four cleaning branch pipes 24 via pipe II5, and each cleaning branch pipe 24 is connected to a cleaning tank III3.

[0057] In this embodiment, the bottoms of cleaning tank I1, cleaning tank II2, and cleaning tank III3 are funnel-shaped structures, as shown in the reference. Figure 6 The drain outlets I1.1 of cleaning tank I1, II2.2 of cleaning tank II2, and III of cleaning tank III3 are all located at the bottom of the tank.

[0058] In this embodiment, filters I25 and II26 are respectively installed on pipe I4 and pipe II5. The filter elements are made of stainless steel and have a filtration accuracy of 80μm.

[0059] In this embodiment, the rear end of the cleaning tank Ⅲ3 is connected to the wastewater treatment system 27 via a pipeline.

[0060] When the system is running, ① Pre-cleaning concentration adjustment: First, open valve I15 and read the pH value of the cleaning solution in cleaning tank I1 using pH meter I7. Level gauge I6 is used to detect the liquid level of the cleaning solution in cleaning tank I1. After the level gauge I6 and pH meter I7 upload the collected liquid level signal and pH value signal to the controller 22 (such as DCS), the controller 22 calculates the alkali concentration through the data analysis module and calculates the dilution factor based on the alkali concentration. When the product of the dilution factor and the current liquid level is greater than the required minimum liquid level, the controller 22 controls valve I15 to close and valve IV18 to open. Demineralized water is then supplied to cleaning tank I1 through demineralized water supply pipeline I12 until the current liquid level is greater than the required minimum liquid level. Then, the controller 22 controls valve IV18 to close.

[0061] ② Concentration adjustment during the cleaning process: If the concentration of the alkali solution is lower than the optimal concentration during cleaning, the corresponding valve on the inlet pipe at the front end of the cleaning tank should be opened to draw alkali solution from the cleaning tank of the previous gradient to replenish the concentration. Once the set concentration is reached, the valve on the inlet pipe should be closed. If the liquid level exceeds the maximum set value at this time, the valve on the drain pipe should be opened to discharge the excess alkali solution to the next stage.

[0062] Taking the example that the alkaline concentration in cleaning tank II2 is lower than the preset optimal concentration, the pH meter II9 on cleaning tank II2 sends the collected signal to the controller 22. The controller 22 then controls the valve II16 on the pipe I4 at the front end of cleaning tank II2 to open, taking high-concentration alkaline solution from cleaning tank I1 to replenish the alkaline concentration in cleaning tank II2. Once the set concentration of the cleaning solution in cleaning tank II2 is reached, the controller 22 controls the valve II16 to close. If the controller 22 detects through the level gauge II8 that the liquid level in cleaning tank II2 exceeds the maximum set value, the controller 22 controls the valve III17 on pipe II5 and the cleaning branch pipe 24 to open, discharging the excess alkaline solution into cleaning tank III3.

[0063] ③ Liquid level adjustment during the cleaning process: If the liquid level drops below the set value due to rapid consumption of downstream alkali solution, the corresponding valve on the inlet pipe at the front end of the cleaning tank must be opened first. The dilution ratio and the required minimum liquid level should be calculated in real time using a pH meter. When the product of the dilution ratio and the current liquid level is greater than the required minimum liquid level, the valve on the inlet pipe should be closed. Then, the valve on the demineralized water supply line should be opened. After the liquid level is replenished to the required minimum liquid level, the valve on the demineralized water supply line should be closed.

[0064] Taking cleaning tank II2 as an example, the level gauge II8 on cleaning tank II2 detects that the alkaline solution in cleaning tank II2 is consumed too quickly, causing the liquid level to drop below the set value. Controller 22 then controls the valve II16 on the pipeline I4 connected to the front end of cleaning tank II2 to open. The data processing module of controller 22 uses the signal collected and uploaded in real time by the pH meter to calculate the dilution ratio and the required minimum liquid level. When the product of the dilution ratio and the current liquid level is greater than the required minimum liquid level, controller 22 controls valve II16 to close and opens valve V19 on the demineralized water supply pipeline II13. After the liquid level is replenished to the required minimum liquid level, valve V19 is closed.

[0065] The alkali solution classification and utilization system in this reduction section operates according to the above process, enabling full utilization of the alkali solution. This system solves the problems of low operational efficiency, insufficient precision, and the need for frequent manual preparation of alkali solutions of various concentrations—all inherent in traditional alkali solution cleaning processes for silicon nitride insulating rings, silicon nitride heat insulation components, and reduction furnace cylinders—which are time-consuming and labor-intensive. Furthermore, this system allows for strict control of the alkali solution concentration for cleaning each part, ensuring its stability and consistent cleaning results. It also reduces the likelihood of damage to components or incomplete cleaning due to improper operation. Simultaneously, this system maximizes the utilization of the alkali solution used in the reduction section, reducing the generation of waste alkali solution, the consumption of caustic soda flakes, and the amount of demineralized water used, thereby lowering production costs.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A system for the graded utilization of alkali solution in a reduction process, characterized in that: The system includes cleaning tank I (1), cleaning tank II (2), and cleaning tank III (3) for cleaning silicon nitride insulating rings, silicon nitride heat insulation components, and reduction furnace cylinders, respectively. The drain port I (1.1) of cleaning tank I (1) is connected to the inlet port II (2.1) of cleaning tank II (2) through pipe I (4). The drain port II (2.2) of cleaning tank II (2) is connected to the inlet port III (3.1) of cleaning tank III (3) through pipe II (5). The cleaning tank Ⅰ (1) is equipped with a level gauge Ⅰ (6) and a pH meter Ⅰ (7), the cleaning tank Ⅱ (2) is equipped with a level gauge Ⅱ (8) and a pH meter Ⅱ (9), the cleaning tank Ⅲ (3) is equipped with a level gauge Ⅲ (10), the cleaning tank Ⅰ (1) is connected to an alkaline inlet pipe (11), and the cleaning tank Ⅰ (1), the cleaning tank Ⅱ (2) and the cleaning tank Ⅲ (3) are respectively connected to a demineralized water supply line Ⅰ (12), a demineralized water supply line Ⅱ (13) and a demineralized water supply line Ⅲ (14); The alkaline inlet pipe (11), pipe I (4), pipe II (5), demineralized water supply line I (12), demineralized water supply line II (13) and demineralized water supply line III (14) are respectively equipped with valve I (15), valve II (16), valve III (17), valve IV (18), valve V (19) and valve VI (20).

2. The alkaline solution classification and utilization system for a reduction section according to claim 1, characterized in that: The front end of the alkali inlet pipe (11) is connected to an alkali tank (21).

3. The alkaline solution classification and utilization system for a reduction section according to claim 1, characterized in that: It also includes a controller (22), which is connected to the level gauge I (6), pH meter I (7), level gauge II (8), pH meter II (9), level gauge III (10), valve I (15), valve II (16), valve III (17), valve IV (18), valve V (19) and valve VI (20) respectively.

4. The alkaline solution classification and utilization system for a reduction section according to claim 1, characterized in that: The cleaning tank Ⅲ (3) is equipped with a pH meter Ⅲ (23).

5. The alkaline solution classification and utilization system for a reduction section according to claim 1, characterized in that: The rear end of the cleaning tank II (2) is connected to 2 to 5 cleaning tanks III (3) via pipes.

6. The alkaline solution classification and utilization system for a reduction section according to claim 5, characterized in that: The rear end of the cleaning tank II (2) is connected to multiple cleaning branch pipes (24) via pipe II (5), and each cleaning branch pipe (24) is connected to a cleaning tank III (3).

7. The alkaline solution classification and utilization system for a reduction section according to claim 1, characterized in that: The bottom of the cleaning pool I (1), cleaning pool II (2) and cleaning pool III (3) is a funnel-shaped structure or a downward-protruding arc-shaped structure. The drain outlet I (1.1) of the cleaning pool I (1), the drain outlet II (2.2) of the cleaning pool II (2) and the drain outlet III of the cleaning pool III (3) are all located at the bottom of the pool.

8. The alkaline solution classification and utilization system for a reduction section according to claim 1, characterized in that: Filters are installed on both pipe I (4) and pipe II (5).

9. A system for the graded utilization of alkali solution in a reduction section according to claim 8, characterized in that: The filter element is made of stainless steel and has a filtration accuracy of 10~80μm.

10. A system for the graded utilization of alkali solution in a reduction section according to claim 1, characterized in that: The rear end of the cleaning tank Ⅲ (3) is connected to the wastewater treatment system (27) via a pipe.

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