Polycrystalline silicon rectification process control system and control method thereof

Abstract

The invention discloses a polycrystalline silicon rectification process control system and a control method thereof, the system comprises a six-stage rectification tower, manual operation points and process control logic are combed, optimization control points are found out, a process control scheme is perfected, automatic detection and control hardware are supplemented, and multi-condition automatic judgment and complex control programs are combined, so that the rectification process of polycrystalline silicon is realized. The problems of misoperation and important operation omission easily caused by manual operation can be solved, the process control is unified, the system control is more stable, the operation is more accurate, and the full-flow automatic intelligent control of the rectification process is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of polysilicon distillation process control, and in particular to a polysilicon distillation process control system and a control method thereof. Background Art

[0002] The distillation process is an important process in the production of polysilicon. In the distillation process, trichlorosilane and silicon tetrachloride are separated and purified according to the boiling point differences of the components in the chlorosilane mixture to obtain high-purity products for the production of polysilicon.

[0003] 1. Selection and design of distillation tower The type of polysilicon distillation tower is plate tower. The advantages of plate tower are mainly reflected in its simple structure, convenient operation, high heat transfer efficiency and energy saving.

[0004] 1. Simple structure and easy operation: The design of the polysilicon distillation plate tower is relatively simple, which makes its operation and maintenance relatively easy. During the distillation process, the plate tower can provide a large gas-liquid contact area, which is conducive to the separation and purification of substances.

[0005] 2. High heat transfer efficiency: The plate tower has good heat transfer performance and can complete the heating and cooling process of the material in a relatively short time, thereby improving the distillation efficiency. This is of great significance for improving the production efficiency and product quality of polysilicon.

[0006] 3. Energy saving: The design of the polysilicon distillation plate tower focuses on energy saving. By optimizing the steam heating system, energy consumption is reduced while meeting the basic guarantee of the PPb-level impurity index of trichlorosilane, which helps to reduce production costs and improve the economic benefits of the enterprise.

[0007] 4. Strong adaptability: The plate tower has strong adaptability to materials and can handle different types of chlorosilanes to ensure material purity and product quality in the polysilicon production process.

[0008] 2. Temperature and pressure control In the distillation process, the control of temperature and pressure is crucial, which directly affects the quality and output of the product. Distillation is a physical and chemical process that uses the difference in boiling points of substances to separate them. By controlling the pressure and temperature in the tower, different components can be effectively separated.

[0009] 1. Temperature control: During the distillation process, temperature control is crucial to the purity and yield of the product. The temperature of the top, bottom and each section of the tower needs to be accurately controlled through a steam heating system to ensure that chlorosilane is separated at an appropriate temperature.

[0010] 2. Pressure control: The stability of system pressure has a direct impact on the gas-liquid balance of the distillation process. It is necessary to use a vacuum system or a pressure regulation system to ensure the stability of the pressure in the tower and avoid the impact of pressure fluctuations on the distillation effect.

[0011] 3. Reflux ratio control The reflux ratio is defined as the ratio of the flow rate returning to the distillation tower to the flow rate at the top of the tower. It is an important control parameter in the distillation operation, which directly affects the separation effect and energy consumption of the distillation process.

[0012] 1. Reflux ratio setting: According to the separation characteristics of chlorosilane and the purity requirements of the product, set a reasonable reflux ratio. The size of the reflux ratio directly affects the purity and energy consumption of the product. By adjusting the reflux ratio, the distillation effect can be optimized and energy consumption can be reduced.

[0013] 2. Dynamic adjustment: During the distillation process, the reflux ratio is dynamically adjusted according to the analysis results of the top and bottom products and the distillation effect to ensure the stability of product purity and the continuity of the distillation process.

[0014] 4. Control of Dichlorosilane Concentration Controlling the concentration of dihydrogen dichlorosilane in the distillation process is an important step in ensuring the quality and efficiency of polysilicon production.

[0015] 1. The role of dichlorosilane in polysilicon production: Dichlorosilane is one of the key raw materials in polysilicon production, and its purity and concentration directly affect the quality and performance of polysilicon. In the preparation process of polysilicon, dichlorosilane is usually reduced to silicon by thermal reduction, and then grown into polysilicon. Therefore, controlling the concentration of dichlorosilane is crucial to ensure the purity, crystallinity and photoelectric conversion efficiency of polysilicon.

[0016] 2. Control of dichlorosilane concentration: ①Synthetic distillation process: trichlorosilane and dichlorosilane in the raw materials are separated by a synthetic distillation tower. During the separation process, it is necessary to control parameters such as the temperature, pressure and reflux ratio at the top and bottom of the tower to ensure the separation efficiency and purity of dichlorosilane.

[0017] ② Recovery and distillation process: Recover and purify dichlorosilane from tail gas and other by-products in the production process. Dichlorosilane is separated from other impurities through a recovery distillation tower to obtain high-purity dichlorosilane for production use.

[0018] ③ Real-time monitoring and adjustment: Use the DCS system to automatically control the production process. Set the target value of dichlorosilane concentration control and automatically adjust process parameters such as temperature, pressure, flow rate, etc. according to real-time monitoring results to ensure stable control of dichlorosilane concentration.

[0019] 5. Material balance and impurity control 1. Material balance: Ensure the balance of materials during the distillation process to avoid material loss and contamination. By accurately measuring and monitoring material flow, timely adjust operating parameters to ensure the smooth progress of the distillation process.

[0020] 2. Impurity removal: Chlorosilane often contains impurities such as boron and phosphorus, which have a serious impact on the performance of polysilicon products. It is necessary to effectively remove these impurities and improve the purity of the product through multi-stage distillation, adsorption, chemical treatment and other methods.

[0021] At present, the operation control in the distillation process is still manually operated by the main control. Some equipment and pipelines on site are often switched and still manually operated by on-site inspections. The operation frequency is high, and the main problems are as follows: 1. Inaccurate operation. For example, six distillation towers are connected in series and parallel for synthetic distillation. Once the incoming material load fluctuates, the master controller needs to adjust the six towers in turn, which requires a high degree of reliance on the master controller's operating skills and experience. The actions of each master controller cannot be completely consistent, and there are differences in operation. During the operation, there are process fluctuations caused by operational differences, which affects the stability of the system and the effect of distillation.

[0022] 2. The probability of misoperation is high. For points where operation control is frequent or complex, employees are prone to misoperation during operation. For example, the top extraction regulating valve circuit of synthetic distillation tower 6 automatically controls the flow. When the main control inputs the flow setting value, there is a misinput, which causes the regulating valve to close, causing the anti-disproportionated silicon tetrachloride to be cut off and the pump to stop due to underflow. When discharging slag from synthetic distillation tower 6, it is necessary to conduct on-site inspection and valve replacement. There is a case of opening the wrong valve during inspection, resulting in an excessively high liquid level in the slag mixing tank, posing a safety risk.

[0023] 3. The workload of employees is heavy. The main control needs to be operated manually more than 700 times per shift; on-site inspections require an average of 4 hours of manual operation per person per shift. During work, there is not much time to maintain the equipment, which reduces the effect of equipment maintenance and increases the insecurity of the device.

[0024] 4. The operating environment of employees poses a safety risk. Currently, some pipeline switching operations require climbing up the pipe gallery. The ladder is slippery on rainy days, and on-site inspectors may fall and get injured during operation.

[0025] Based on the above situation, in the actual production process, in order to improve the quality of distillation products and avoid product quality degradation and safety accidents caused by manual operation of personnel, the implementation of full-process automated intelligent control is the key. Summary of the invention

[0026] The present invention aims to provide a polysilicon distillation process control system and a control method thereof. By sorting out the manual operation points and process control logic, finding the optimized control points, improving the process control scheme, and completing the automated detection and control hardware, combined with multi-condition automatic judgment and complex control procedures, the problems of misoperation and omission of important operations that are prone to occur in manual operation can be solved. The process control is unified, the system control is more stable, the operation is more precise, and the full-process automated intelligent control of the distillation process can be achieved.

[0027] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows: A polysilicon distillation process control system comprises a 6-stage distillation tower, wherein the top outlet of the distillation tower is connected to a reflux tank, the distillation tower kettle is provided with a heat exchanger, the bottom of the reflux tank is connected to a reflux pump, the reflux outlet of the reflux pump is connected to the top of the distillation tower of this stage, the top of the distillation tower is provided with an exhaust gas discharge pipe, and the exhaust gas discharge pipe is connected to an exhaust gas condensing device. The extraction outlet of the reflux pump of the 1st tower is connected to the feed inlet of the 2nd tower, the extraction outlet of the reflux pump of the 2nd tower is connected to the anti-disproportionation device, the extraction outlet of the reflux pump of the 3rd tower is connected to the feed inlet of the 4th tower, the extraction outlet of the reflux pump of the 4th tower is connected to the raw material tank, the extraction outlet of the reflux pump of the 5th tower is connected to the trichlorosilane refining tank, and the extraction outlet of the reflux pump of the 6th tower is connected to the silicon tetrachloride storage tank; the feed inlet of the 1st tower is connected to the raw material tank, and the tower kettle outlet of the 1st tower is connected to the feed inlet of the 6th tower; the tower kettle outlet of the 2nd tower is connected to the feed inlet of the 3rd tower, and the tower kettle outlet of the 3rd tower is connected to the raw material tank; the tower kettle outlet of the 4th tower is connected to the feed inlet of the 5th tower, the tower kettle outlet of the 5th tower is connected to the raw material tank, and the tower kettle outlet of the 6th tower is connected to the slag mixing tank; The tail gas discharge pipe outlet of the distillation tower is provided with a venting regulating valve II, the top of the distillation tower is provided with a pressure sensor II, the reflux tank is provided with a liquid level gauge IIa, the distillation tower kettle is provided with a liquid level gauge IIb, and the distillation tower kettle outlet is provided with a flow meter IIb and a tower kettle extraction regulating valve IIa; The reflux outlet of the reflux pump is provided with a reflux regulating valve II and a flow meter IIc; the production outlet of the reflux pump is provided with a tower top production regulating valve IIb and a flow meter IId; The distillation tower is provided with a temperature sensor IIa at the top, a temperature sensor IIb at the bottom, and a temperature sensor IIc in the middle. The heating medium pipelines of the heat exchangers of the 1st tower, the 3rd tower and the 6th tower are connected to the steam main pipeline and heated by steam; the top outlets of the 3rd tower, the 5th tower and the 6th tower are respectively connected to the inlet of the heating medium pipeline of the heat exchanger of the upper distillation tower, and the inlet of the reflux tank of the 3rd tower, the 5th tower and the 6th tower are respectively connected to the outlet of the heating medium pipeline of the heat exchanger of the upper distillation tower; the 2nd tower, the 4th tower and the 5th tower are heated by the material temperature of the lower distillation tower instead of directly using steam, so as to achieve energy saving; The heating medium inlet of the heat exchanger of the distillation tower is provided with a heating medium regulating valve and a temperature sensor IId, and the steam main pipeline is provided with a pressure sensor I; the heating medium pipeline inlet of the heat exchanger of the 1st tower, 3rd tower and 6th tower is provided with a flow meter IIa; The feed inlet of the first-stage tower is provided with a feed regulating valve I and a flow meter Ib, and the raw material tank is provided with a liquid level meter I; There are two slag material stirring tanks, each of which is connected to a nitrogen pipeline IV, and each of which is provided with a nitrogen shut-off valve IV. The slag mixing tank is respectively provided with a venting pipeline IV, and the venting pipeline IV is respectively provided with a venting shut-off valve IV; The connecting pipes between the slag mixing tank and the 6-stage tower kettle are respectively provided with a feed cut-off valve IVa; The discharge port of each slag mixing tank is connected to the slag slurry process I and the slag slurry process II respectively, and the connecting pipeline between the discharge port of the slag mixing tank and the slurry process is provided with a feed cut-off valve IV; The connecting pipelines between the slag material mixing tank and the slag slurry process I and the slag slurry process II are respectively provided with a discharge cut-off valve IV; The slurry process I and the slurry process II are respectively provided with two receiving tanks, and the feed inlets of the receiving tanks are provided with feed cut-off valves IVb; The discharge ports of the slag mixing tanks are respectively connected with flushing clear liquid pipelines, and the flushing clear liquid pipelines are respectively provided with flushing cut-off valves IV; The slag mixing tank is equipped with a liquid level gauge IV, a pressure sensor IV and a temperature sensor IV; The tail gas condensing device comprises a tail gas condenser and a condensate tank, wherein the inlet of the tail gas condenser is connected to the tail gas discharge pipe of the distillation tower, the outlet of the tail gas condenser is connected to the inlet of the condensate tank, the condensate tank is provided with a liquid level gauge III, the outlet of the condensate tank is connected to the raw material tank, and the connecting pipeline between the condensate tank and the raw material tank is provided with a condensate pump, a production regulating valve III and a flow meter III; The polysilicon distillation process control system also includes a dripping liquid tank, the inlet of the dripping liquid tank is connected to the dripping liquid pipeline, the outlet of the dripping liquid tank is connected to the condensate tank, a vent is provided at the top of the dripping liquid tank, the vent is connected to the tail gas condenser, the dripping liquid tank is also connected to a nitrogen pipeline III, the inlet of the dripping liquid tank is provided with a feed cut-off valve III, the nitrogen pipeline III is provided with a nitrogen cut-off valve III, the outlet of the dripping liquid tank is provided with a discharge cut-off valve III, the vent is provided with a vent cut-off valve III, and the dripping liquid tank is provided with a pressure sensor III and a liquid level meter III.

[0028] A control method for a polysilicon distillation process control system includes: distillation tower top venting flow control, reflux flow control, tower top extraction flow control, tower bottom extraction flow control and tower bottom temperature control.

[0029] The venting pressure control of the distillation tower top includes: automatic control of the tower top venting regulating valve II and the tower top pressure single loop, and the PID loop action form is positive action; setting the tower top control pressure, monitoring the tower top pressure value in real time through the pressure sensor II, when there is a positive deviation between the tower top real-time pressure value and the set pressure value, the venting regulating valve II increases the output opening and automatically adjusts the pressure value; when there is a negative deviation between the tower top real-time pressure value and the set pressure value, the venting regulating valve II reduces the output opening and automatically adjusts the pressure value; so that the tower top pressure value of the distillation tower is basically stably maintained at the set value.

[0030] The distillation tower reflux flow control comprises: The reflux regulating valve II of the first-stage tower is automatically controlled by a single loop of the reflux flow; the reflux flow is set, and the reflux flow of the distillation tower is monitored in real time by the flow meter Ⅱc at the reflux outlet of the reflux pump of the first-stage tower. When there is a positive deviation between the real-time reflux flow value and the set reflux flow value, the reflux regulating valve Ⅱ reduces the output opening and automatically adjusts the reflux flow value; when there is a negative deviation between the real-time reflux flow value and the set reflux flow value, the reflux regulating valve Ⅱ increases the output opening and automatically adjusts the reflux flow value; so that the reflux flow value of the distillation tower is basically stable and maintained at the set value.

[0031] The reflux regulating valve II of the second-stage tower is cascade-controlled with the reflux flow rate and the tower top temperature; the tower top temperature control is the main loop, and the PID loop action form is positive action; the tower top control temperature is set, and the tower top temperature value is monitored in real time through the temperature sensor IIa. When there is a positive deviation between the real-time tower top temperature value and the set temperature value, the reflux flow output is increased to automatically adjust the temperature value; when there is a negative deviation between the real-time tower top temperature value and the set temperature value, the reflux flow output is reduced to automatically adjust the temperature value; so that the top temperature value of the distillation tower is basically stable and maintained at the set value; the reflux flow control is the secondary loop, the PID loop action form is reverse action; the reflux flow output of the temperature control main loop is used as the set reflux flow, and the reflux flow of the distillation tower is monitored in real time through the flow meter Ⅱc at the reflux outlet of the reflux pump of the second-stage tower. When there is a positive deviation between the real-time reflux flow value and the set reflux flow value, the reflux regulating valve Ⅱ reduces the output opening and automatically adjusts the reflux flow value; when there is a negative deviation between the real-time reflux flow value and the set reflux flow value, the reflux regulating valve Ⅱ increases the output opening and automatically adjusts the reflux flow value; so that the reflux flow value of the distillation tower is basically stable and maintained at the set value.

[0032] The reflux regulating valve II of the 3-stage tower, 5-stage tower and 6-stage tower is controlled in cascade with the tower kettle liquid level and reflux flow rate; the tower kettle liquid level control is the main loop, and the PID loop action form is the reaction; the tower kettle control liquid level is set, and the tower kettle liquid level value is monitored in real time by the liquid level meter IIb. When there is a positive deviation between the real-time tower kettle liquid level value and the set liquid level value, the reflux flow output is reduced to automatically adjust the liquid level value; when there is a negative deviation between the real-time tower kettle liquid level value and the set liquid level value, the reflux flow output is increased to automatically adjust the liquid level value; so that the tower kettle liquid level value of the distillation tower is basically stable and maintained at the set value. The reflux flow control is a secondary loop, and the PID loop action form is reverse action; the reflux flow output of the tower bottom liquid level control main loop is used as the set reflux flow, and the reflux flow of the distillation tower is monitored in real time by the flow meter Ⅱc at the reflux outlet of the reflux pump. When there is a positive deviation between the real-time reflux flow value and the set reflux flow value, the reflux regulating valve Ⅱ reduces the output opening to automatically adjust the reflux flow value; when there is a negative deviation between the real-time reflux flow value and the set reflux flow value, the reflux regulating valve Ⅱ increases the output opening to automatically adjust the reflux flow value; so that the reflux flow value of the distillation tower is basically stable and maintained at the set value.

[0033] The reflux regulating valve II of the 4-stage tower is controlled in series with the reflux tank liquid level and reflux flow rate; the reflux tank liquid level control is the main loop, and the PID loop action form is positive action; the reflux tank control liquid level is set, and the reflux tank liquid level value is monitored in real time through the level meter IIa. When there is a positive deviation between the real-time liquid level value of the reflux tank and the set liquid level value, the reflux flow output is increased to automatically adjust the liquid level value; when there is a negative deviation between the real-time liquid level value of the reflux tank and the set liquid level value, the reflux flow output is reduced to automatically adjust the liquid level value; so that the liquid level value of the reflux tank of the 4-stage distillation tower is basically stable and maintained at the set value. The reflux flow control is a secondary loop, and the PID loop action form is reverse action; the reflux flow output of the reflux tank liquid level control main loop is used as the set reflux flow, and the reflux flow of the distillation tower is monitored in real time by the flow meter Ⅱc at the reflux outlet of the reflux pump. When there is a positive deviation between the real-time reflux flow value and the set reflux flow value, the reflux regulating valve Ⅱ reduces the output opening to automatically adjust the reflux flow value; when there is a negative deviation between the real-time reflux flow value and the set reflux flow value, the reflux regulating valve Ⅱ increases the output opening to automatically adjust the reflux flow value; so that the reflux flow value of the distillation tower is basically stable and maintained at the set value.

[0034] The top extraction flow control includes: The top production regulating valve Ⅱb of the 1st tower, 3rd tower and 6th tower is controlled in series with the reflux tank liquid level and the top production flow rate; the reflux tank liquid level control is the main loop, and the PID loop action form is positive action; the reflux tank control liquid level is set, and the reflux tank liquid level value is monitored in real time by the level meter Ⅱa. When there is a positive deviation between the real-time liquid level value of the reflux tank and the set liquid level value, the top production flow output is increased to automatically adjust the liquid level value; when there is a negative deviation between the real-time liquid level value of the reflux tank and the set liquid level value, the top production flow output is reduced to automatically adjust the liquid level value; so that the liquid level value of the reflux tank of the distillation tower is basically stable and maintained at the set value. The top extraction flow control is a secondary loop, and the PID loop action form is a reverse action; the top extraction flow output of the reflux tank liquid level control main loop is used as the set extraction flow, and the top extraction flow of the distillation tower is monitored in real time through the top extraction flow meter Ⅱd. When there is a positive deviation between the real-time extraction flow value and the set extraction flow value, the top extraction regulating valve Ⅱb reduces the output opening to automatically adjust the top extraction flow value; when there is a negative deviation between the real-time extraction flow value and the set extraction flow value, the top extraction regulating valve Ⅱb increases the output opening to automatically adjust the top extraction flow value; so that the top extraction flow value of the distillation tower is basically stable and maintained at the set value.

[0035] The top extraction regulating valve Ⅱb of the 2-stage tower is automatically controlled by a single loop with the reflux tank liquid level, and the PID loop action form is positive action. Set the reflux tank control liquid level, and monitor the reflux tank liquid level value in real time through the level meter Ⅱa. When there is a positive deviation between the real-time liquid level value of the reflux tank and the set liquid level value, increase the output opening of the top extraction regulating valve Ⅱb to automatically adjust the liquid level value; when there is a negative deviation between the real-time liquid level value of the reflux tank and the set liquid level value, reduce the output opening of the top extraction regulating valve Ⅱb to automatically adjust the liquid level value; so that the liquid level value of the reflux tank of the distillation tower is basically stable and maintained at the set value.

[0036] The top extraction regulating valve Ⅱb of the 4-stage tower and the 5-stage tower is automatically controlled by a single loop with the top extraction flow, and the PID loop action form is reverse action. The top extraction flow is set, and the top extraction flow of the distillation tower is monitored in real time through the top extraction flow meter Ⅱd. When there is a positive deviation between the real-time extraction flow value and the set extraction flow value, the top extraction regulating valve Ⅱb reduces the output opening to automatically adjust the top extraction flow value; when there is a negative deviation between the real-time extraction flow value and the set extraction flow value, the top extraction regulating valve Ⅱb increases the output opening to automatically adjust the top extraction flow value; so that the top extraction flow value of the distillation tower is basically stable and maintained at the set value.

[0037] The tower bottom extraction flow control includes: The kettle extraction regulating valve Ⅱa of the 1st, 2nd and 4th towers is controlled in cascade with the kettle liquid level and kettle extraction flow rate; the kettle liquid level control is the main loop, and the PID loop action form is positive; the kettle control liquid level is set, and the kettle liquid level value is monitored in real time by the level meter Ⅱb. When there is a positive deviation between the real-time kettle liquid level value and the set liquid level value, the kettle extraction flow output is increased to automatically adjust the liquid level value; when there is a negative deviation between the real-time kettle liquid level value and the set liquid level value, the kettle extraction flow output is reduced to automatically adjust the liquid level value; so that the kettle liquid level value of the distillation tower is basically stable and maintained at the set value. The tower bottom extraction flow control is a secondary loop, and the PID loop action form is a reaction; the tower bottom extraction flow output of the tower bottom liquid level control main loop is used as the set extraction flow, and the tower bottom extraction flow of the distillation tower is monitored in real time through the tower bottom extraction flow meter Ⅱb. When there is a positive deviation between the real-time extraction flow value and the set extraction flow value, the tower bottom extraction regulating valve Ⅱa reduces the output opening to automatically adjust the tower bottom extraction flow value; when there is a negative deviation between the real-time extraction flow value and the set extraction flow value, the tower bottom extraction regulating valve Ⅱa increases the output opening to automatically adjust the tower bottom extraction flow value; so that the tower bottom extraction flow value of the distillation tower is basically stable and maintained at the set value.

[0038] The 3-stage tower and 5-stage tower are controlled by the single loop of the tower kettle extraction regulating valve Ⅱa and the tower kettle extraction flow rate, and the PID loop action form is reverse action. The tower kettle extraction flow rate is set, and the tower kettle extraction flow rate of the distillation tower is monitored in real time through the tower kettle extraction flow meter Ⅱb. When there is a positive deviation between the real-time extraction flow rate value and the set extraction flow rate value, the tower kettle extraction regulating valve Ⅱa reduces the output opening to automatically adjust the tower kettle extraction flow rate value; when there is a negative deviation between the real-time extraction flow rate value and the set extraction flow rate value, the tower kettle extraction regulating valve Ⅱa increases the output opening to automatically adjust the tower kettle extraction flow rate value; so that the tower kettle extraction flow rate value of the distillation tower is basically stable and maintained at the set value.

[0039] The 1st, 3rd and 6th level towers also include tower kettle temperature control: The heating medium regulating valve and the tower kettle temperature of the 1st and 3rd towers are automatically controlled by a single loop, and the PID loop action form is reverse action; the tower kettle control temperature is set, and the tower kettle temperature value is monitored in real time by temperature sensor Ⅱb. When there is a positive deviation between the real-time tower kettle temperature value and the set temperature value, the heating medium regulating valve reduces the output opening and automatically adjusts the temperature value; when there is a negative deviation between the real-time tower kettle temperature value and the set temperature value, the heating medium regulating valve increases the output opening and automatically adjusts the temperature value; so that the tower kettle temperature value of the distillation tower is basically stable and maintained at the set value.

[0040] The heating medium regulating valve of the 6-stage tower is controlled in series with the steam flow and the tower kettle temperature. The tower kettle temperature control is the main loop, and the PID loop works in a reverse manner. The tower kettle control temperature is set, and the tower kettle temperature value is monitored in real time through the temperature sensor Ⅱb. When there is a positive deviation between the real-time temperature value of the tower kettle and the set temperature value, the steam flow output is reduced to automatically adjust the temperature value; when there is a negative deviation between the real-time temperature value of the tower kettle and the set temperature value, the steam flow output is increased to automatically adjust the temperature value; so that the tower kettle temperature value of the distillation tower is basically stable and maintained at the set value. Steam flow control is a secondary loop, and the PID loop works in a reverse manner. The steam flow output of the tower kettle temperature control main loop is used as the set flow, and the steam flow of the distillation tower is monitored in real time through the steam flow meter Ⅱa. When there is a positive deviation between the real-time steam flow value and the set steam flow value, the heating medium regulating valve reduces the output opening and automatically adjusts the steam flow value; when there is a negative deviation between the real-time steam flow value and the set steam flow value, the heating medium regulating valve increases the output opening and automatically adjusts the steam flow value; so that the steam flow value of the distillation tower is basically stable and maintained at the set value.

[0041] The 1st-stage tower, 3rd-stage tower and 6th-stage tower also include steam automatic adjustment control, including the following steps: S101: Setting parameters: setting sampling time, triggering time, steam main set pressure difference PI-SP and heating medium regulating valve opening adjustment set value OUT-SP; S102: monitor the pressure in the steam main in real time through the pressure sensor 1, and calculate the average value of the previous 6 sampling pressures; S103: Calculate the difference between the current pressure of the steam main and the average pressure of the steam main, and set judgment condition 1 and judgment condition 2; The judgment condition 1 is: the difference between the current pressure of the steam main and the average pressure of the steam main is greater than or equal to the set pressure difference PI-SP of the steam main; The judgment condition 2 is: when the difference between the current pressure of the steam main and the average pressure of the steam main is less than the set pressure difference PI-SP of the steam main; S104: When neither condition 1 nor condition 2 is satisfied, continue to make real-time judgment; When condition 1 is met within T2 consecutive times, the heating medium regulating valve loop mode is switched to manual, and the valve opening is reduced to OUT-SP; after stabilization for 2S, the heating medium regulating valve loop mode is switched to automatic, and the last automatic mode flow setting value is restored; When condition 2 is met within the continuous T2 time, the heating medium regulating valve circuit mode is switched to manual, and the valve opening is widened OUT-SP; after stabilizing for 2S, the heating medium regulating valve circuit mode is switched to automatic, and the last automatic mode flow setting value is restored.

[0042] The first-stage tower also includes automatic feed control: the feed amount of the first-stage tower is automatically adjusted according to the liquid level of the raw material tank, so as to realize automatic control and stable regulation of the feed amount; The automatic feeding control comprises: S201: Setting parameters: Setting the interval time for adjusting the feed set value of the PID loop of the feed regulating valve I; Setting the upper and lower limits of the feed flow set value in the automatic mode of the PID loop of the feed regulating valve I; Setting the upper and lower limits, upper and lower limits of the liquid level of the raw material tank; S202: Feed regulating valve I and feed flow rate are automatically controlled in a single loop, and the PID loop action form is a reaction; the feed flow rate of the distillation tower is monitored in real time by flow meter Ib, and when there is a positive deviation between the real-time feed flow rate value and the set flow rate value, the feed regulating valve I reduces the output opening to automatically adjust the feed flow rate value; when there is a negative deviation between the real-time feed flow rate value and the set flow rate value, the feed regulating valve I increases the output opening to automatically adjust the feed flow rate value; when it is necessary to reduce the output opening of the feed regulating valve I and the feed flow rate set value reaches the lower limit, no adjustment is made; when it is necessary to increase the output opening of the feed regulating valve I and the feed flow rate set value reaches the upper limit, no adjustment is made; so that the feed flow rate value of the distillation tower is basically stable and maintained at the set value; S203: When the liquid level of the raw material tank is ≥ the upper limit, and the liquid level is < the upper and lower limits, the feed flow setting value of the feed regulating valve I PID loop is increased by SP1; after adjustment, after the adjustment interval time, the program continues to make real-time judgments; S204: When the liquid level of the raw material tank is greater than the lower limit and the liquid level is less than or equal to the lower limit, the feed flow setting value of the feed regulating valve I PID loop is reduced by SP1; after adjustment, after the adjustment interval time, the program continues to make real-time judgments; S205: When the liquid level of the raw material tank is ≥ the upper limit, the feed flow setting value of the feed regulating valve I PID loop is increased by SP2; after adjustment, after the adjustment interval time, the program continues to make real-time judgments; S206: When the liquid level of the raw material tank is ≤ the lower limit, the feed flow setting value of the feed regulating valve I PID loop is reduced by SP2; after adjustment, after the adjustment interval time, the program continues to make real-time judgments.

[0043] The first-stage tower also includes automatic temperature control in the tower, including the following steps: S301: Setting parameters: Setting the temperature setting value adjustment interval of the heating medium regulating valve PID loop; Setting the upper and lower limits of the temperature setting value in the automatic mode of the heating medium regulating valve PID loop; Setting the upper upper limit, upper limit, lower lower limit and lower limit of the temperature in the first-stage tower; S302: When the medium temperature of the first-stage tower is ≥ the upper limit, and the medium temperature is < the upper and lower limits, the temperature setting value of the heating medium regulating valve PID loop is increased by SP1; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments; S303: When the medium temperature of the first-stage tower is greater than the lower limit and the medium temperature is less than or equal to the lower limit, the temperature setting value of the heating medium regulating valve PID loop is reduced by SP1; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments; S304: When the temperature in the first-stage tower is ≥ the upper limit, the temperature setting value of the heating medium regulating valve PID loop is increased by SP2; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments; S305: When the temperature in the first-stage tower is ≤ the lower limit, the temperature setting value of the heating medium regulating valve PID loop is reduced by SP2; after adjustment, after the adjustment interval time, the program continues to make real-time judgments.

[0044] The distillation tower also includes an automatic reflux ratio adjustment control, which automatically adjusts the reflux ratio according to the extraction flow rate at the top of the distillation tower to ensure the stability of the reflux of the distillation tower, ensure the distillation effect, and reduce energy consumption; including: S401: input the set value of the reflux ratio (ratio of reflux flow rate to tower top production flow rate); S402: The flow setting value of the reflux regulating valve II of the distillation tower is automatically adjusted to the product of the reflux ratio setting value and the tower top extraction flow rate; S403: The PID control loop of the reflux regulating valve II acts in a reverse manner; the real-time value of the top tower reflux flow is monitored in real time by the flow meter IIc. When there is a positive deviation between the real-time value of the reflux flow and the set value of the reflux flow, the reflux regulating valve II reduces the output opening to automatically adjust the reflux flow; when there is a negative deviation between the real-time value of the reflux flow and the set value of the reflux flow, the reflux regulating valve II increases the output opening to automatically adjust the reflux flow; so that the reflux flow value of the distillation tower is basically stable and maintained at the set value.

[0045] The 6-stage tower also includes automatic slag discharge control for the tower kettle, and automatic timed slag discharge for the tower kettle to prevent high-boiling materials from accumulating in the tower kettle, causing blockage of the tower kettle, wear of the reboiler, and the risk of material leakage, including: S501: respectively set the material receiving amount of the two slag mixing tanks.

[0046] S502: judging the slag discharge conditions of the synthetic distillation 6-stage tower, including: when the liquid level of one of the slag mixing tanks is less than 54%, the pressure is less than 0.2MPa, and the venting cut-off valve IV is in an open state, the slag mixing tank is discharged and the material is fed; when both slag mixing tanks meet the above conditions, the slag mixing tank with a higher liquid level is discharged and the material is fed; S503: When one of the slag mixing tanks meets the conditions described in S502, the nitrogen shut-off valve IV of the slag mixing tank that meets the slag discharge conditions is closed, the vent shut-off valve IV of the slag mixing tank that meets the slag discharge conditions is opened, the feed shut-off valve IVa of the slag mixing tank that does not meet the slag discharge conditions is closed, and the timing RET1 is started; After the above-mentioned shut-off valve is fed back to the right position, the shut-off valve IVa of the slag mixing tank that meets the slag discharge conditions is opened, and the timing RET2 is started; When the liquid level of the slag mixing tank that meets the slag discharge conditions rises by more than the set material receiving amount, close the feed cut-off valve IVa of the mixing tank; When RET2 counts down to 30 minutes, and the feed shut-off valve of the slag mixing tank that meets the slag discharge conditions is not closed and is still feeding, it will be prompted: The slag discharge of the 6-stage synthetic distillation tower has timed out, please confirm.

[0047] S504: When the RET1 timing reaches 160 minutes, repeat steps S502-S503. When both slag mixing tanks do not meet the material receiving conditions, the circulation conditions are not met, and it is prompted: the 6-stage tower slag discharge conditions are not met, waiting for the slag mixing tank to meet the material receiving conditions.

[0048] The slag mixing tank includes automatic discharging control, including the following steps: S601: setting the discharge amount of two slag mixing tanks respectively; S602: Determine the discharge conditions of the slag mixing tank: When the liquid level of one slag mixing tank is greater than 65% and the liquid level of the other slag mixing tank is less than or equal to 65%, the slag mixing tank with a liquid level greater than 65% shall discharge the material; When the liquid levels of the two slag mixing tanks are both greater than 65%, the slag mixing tank with the higher liquid level will discharge the material; When the liquid levels of the two slag mixing tanks are both ≤65%, the slag mixing tank with a liquid level of >54% will discharge the material; When the liquid levels of the two slag mixing tanks are both ≤65%, and when the liquid levels of the two slag mixing tanks are both >54%, the slag mixing tank with the higher liquid level will discharge; When the liquid levels of the two slag mixing tanks are both ≤65%, and when the liquid levels of the two slag mixing tanks are both ≤54%, the liquid level conditions are re-judged.

[0049] S603: Determine the slag material mixing tank for discharging according to the discharging conditions in step S602, and close the venting cut-off valve IV and the feed cut-off valve IVa of the slag material mixing tank for discharging; S604: monitor the pressure in the slag mixing tank of the discharge material in real time through the pressure sensor IV. When the pressure is ≥0.6MPa, execute the next step; when the pressure is <0.6MPa, open the nitrogen cut-off valve IV of the slag mixing tank of the discharge material, charge the pressure to 0.6MPa, close the nitrogen cut-off valve IV, and execute the next step; S605: Determine the discharge path: by default, start from the slurry process I to confirm the discharge conditions each time; Material collection conditions for slurry process I: the feed cut-off valves IVb of the two material collection tanks of the feed process I meet an open state, the discharge cut-off valve IV between the discharge slag mixing tank and the slurry process II is closed, and the discharge cut-off valve IV between the discharge slag mixing tank and the slurry process I is opened; Material receiving conditions of slag slurry process II: the feed cut-off valve IVb of the two receiving tanks of the feed process II meets an open state, the discharge cut-off valve IV between the discharge slag material mixing tank and the slag slurry process I is closed, and the discharge cut-off valve IV between the discharge slag material mixing tank and the slurry process II is opened; S606: Start discharging. When the discharging amount of the slag material mixing tank is greater than the set value or the liquid level in the slag material mixing tank is less than 15%, close the discharging cut-off valve IV and the nitrogen cut-off valve IV of the slag material mixing tank; S607: After closing the discharge cut-off valve IV and the nitrogen cut-off valve IV, open the clear liquid cut-off valve of the discharge slag mixing tank for flushing, and start timing; when the 300s timing is up, close the clear liquid cut-off valve IV of the discharge slag mixing tank, and open the venting cut-off valve IV; S608: During the discharging process, the pressure of the slag mixing tank is maintained between 0.55 and 0.6 MPa. During the discharging process, if the feed cut-off valves IVb of the two receiving tanks of the slurry process I or II are closed, an alarm will be triggered. After confirmation by the main control, the discharging path will be re-confirmed. During the discharging process, if the feed cut-off valves IVb of the two receiving tanks of any slurry process are closed, an alarm will be triggered.

[0050] The reflux tank also includes an automatic adjustment control of the reflux tank liquid level to avoid frequent changes in short-term production affecting downstream processes. At the same time, the reflux tank liquid level can also be automatically adjusted. The automatic adjustment control of the reflux tank liquid level includes: S701: Setting parameters: setting the interval time, setting the upper limit of the flow setting value of the tower top production regulating valve Ⅱb loop, setting the lower limit of the flow setting value, setting the upper limit, upper limit, lower limit and lower limit of the reflux tank liquid level; When the liquid level in the reflux tank is greater than or equal to the upper limit or less than or equal to the lower limit, the flow setting adjustment value of the IIb loop of the distillation tower top extraction regulating valve is SP1; When the liquid level in the reflux tank is greater than or equal to the upper limit or less than or equal to the lower limit, the flow rate of the IIb loop of the distillation tower top extraction regulating valve is set to the adjustment value SP2; S702: When the liquid level in the reflux tank is greater than or equal to the upper limit and the liquid level is less than the upper and lower limits, the flow setting value of the Ⅱb loop of the distillation tower top extraction regulating valve is increased by SP1; after adjustment, the interval time is stabilized and the program continues to make real-time judgments; When the liquid level in the reflux tank is greater than the lower limit and the liquid level is less than or equal to the lower limit L, the flow setting value of the Ⅱb loop of the distillation tower top extraction regulating valve is reduced by SP1; after adjustment, the stable interval time, the program continues to make real-time judgments; S703: When the liquid level of the reflux tank is greater than or equal to the upper limit, the set value of the flow rate of the Ⅱb loop of the distillation tower top extraction regulating valve is increased by SP2; after adjustment, the interval time is stabilized, and the program continues to make real-time judgments; When the liquid level in the reflux tank is less than or equal to the lower limit, the flow setting value of the Ⅱb loop of the distillation tower top extraction regulating valve is reduced by SP2; after adjustment, the stable interval time is T1, and the program continues to make real-time judgments.

[0051] The tail gas condensation device includes a tail gas venting condensate system feeding control method, including: S801: When the liquid level of the tail gas condensate tank is higher than 65%, the condensate pump starts automatically and the opening of the production regulating valve III is opened to 70%; after 10 seconds, the production flow rate is set, and the production regulating valve III automatically adjusts the opening according to the deviation between the real-time value of the production flow rate and the set value; S802: When the liquid level of the tail gas condensate tank is lower than 20%, the condensate pump automatically stops running and the extraction regulating valve III is closed; S803: During operation, if the condensate pump current is lower than 8A and lasts for 10 seconds, the condensate pump stops running and the production regulating valve III is closed.

[0052] The control method of the polysilicon distillation process control system also includes automatic material pressing control of the liquid guiding tank, including: S901: When the liquid level of the guide liquid tank is higher than the set value, first close the feed cut-off valve III, then close the vent cut-off valve III; open the discharge cut-off valve III to drain the tail gas condensate tank, and then open the nitrogen cut-off valve III to pressurize the guide liquid tank; S902: When the liquid level in the shower tank is lower than the set value, first close the nitrogen cut-off valve III, then close the discharge cut-off valve III; open the air cut-off valve III for 10 seconds, and then open the feed cut-off valve III; S903: in step S901, the timing starts after the nitrogen shut-off valve III of the liquid guide tank is opened. When the pressure is charged for more than 3 minutes, an alarm is given, and the program automatically opens the vent shut-off valve first for 10 seconds, and then opens the feed shut-off valve. S904: When the number of drainage reaches 2 times within 60 minutes, an alarm will be issued to prompt the main control that the number of drainage times is too many.

[0053] Beneficial effects of the present invention: 1. In the present invention, by implementing the logic control program, the influence of the operation differences of different operators is avoided, the parameters of the whole process distillation tower are stabilized, the product quality is guaranteed to be stable, and at the same time, through precise control, energy waste is avoided, and energy saving and consumption reduction are achieved. According to the change of the steam main pressure, the opening of the heating medium regulating valve is adjusted in advance to avoid the temperature fluctuation of the distillation tower kettle. According to the set conditions and the set time, the liquid level of the raw material tank is periodically determined, and the flow setting value of the distillation tower feed regulating valve loop is automatically adjusted to maintain the stability of the feed amount, prevent over-adjustment, and avoid quality deviation. According to the temperature change in the distillation tower, the temperature setting value of the distillation tower heating medium regulating valve loop is automatically adjusted, and the single temperature variable control is changed to the tower kettle temperature and the tower temperature dual variable control, which can better match the change of the feed amount and stabilize the distillation tower temperature. The reflux ratio is automatically adjusted according to the distillation tower top extraction flow rate to ensure the stability of the distillation tower reflux ratio, ensure the distillation effect, and reduce energy consumption. The liquid level is determined periodically according to the set conditions and set time, and the set value of the flow rate of the distillation tower top production regulating valve loop is automatically adjusted to control the liquid level balance of the reflux tank while avoiding multiple manual adjustments in a short period of time to ensure the stability of the production volume.

[0054] 2. In the present invention, the 6-stage distillation tower is fully automated through the implementation of the logic control program, thereby reducing the operating load of personnel. The 6-stage distillation tower is a silicon tetrachloride removal tower, which removes high-boiling silicon tetrachloride products. The tower kettle is automatically discharged at regular intervals to prevent high-boiling products from accumulating in the tower kettle, causing blockage of the tower kettle, wear of the reboiler, and the risk of material leakage. The slag mixing tank is then sent to the slag slurry process for processing and recycling: the material is automatically discharged according to the liquid level of the slag mixing tank, and no on-site inspection and manual operation are required, thereby reducing the labor load of employees.

[0055] 3. In the present invention, through the implementation of the logic control program, the tail gas discharged from the distillation is condensed and reused automatically, thereby improving resource utilization and reducing environmental pollution. The tail gas from the 1st to 6th stage distillation tower is discharged to the tail gas condenser, and the tail gas is condensed and converted from gas to liquid, collected in a condensate tank, and finally pumped into the raw material tank area for reuse, thereby realizing the recycling of resources.

[0056] 4. In the present invention, through the implementation of the logic control program, the distillation leaching liquid is fully automatically collected and reused, which improves the efficiency of resource utilization, reduces waste, and reduces the negative impact on the environment. During the operation of the distillation device, equipment such as pumps, filters, and samplers will discharge a certain amount of leaching liquid regularly or irregularly. These leaching discharge liquids contain materials. If they are discharged directly, it will not only cause waste of resources, but also may pollute the environment. The leaching discharge liquid of each device is collected in a leaching liquid tank, then fed to a condensate tank, and finally pumped into the raw material tank area for reuse to achieve the recycling of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic diagram of the structure of the polysilicon distillation process control system of the present invention.

[0058] Figure 2 It is a schematic diagram of the structure of the tail gas condensing device of the polysilicon distillation process control system of the present invention.

[0059] Figure 3 It is a schematic diagram of the structure of the dripping liquid tank of the polysilicon distillation process control system of the present invention.

[0060] Figure 4 This is a schematic diagram of the slag stirring tank structure of the polysilicon distillation process control system of the present invention.

[0061] Among them, 1. 1st-stage tower; 2. 2nd-stage tower; 3. 3rd-stage tower; 4. 4th-stage tower; 5. 5th-stage tower; 6. 6th-stage tower; 7. Reflux tank; 8. Heat exchanger; 9. Reflux pump; 10. Tail gas discharge pipe; 11. Tail gas condenser; 12. Anti-disproportionation device; 13. Raw material tank; 14. Trichlorosilane refining tank; 15. Silicon tetrachloride storage tank; 16. Slag material mixing tank; 17. Steam main pipeline; 18. Nitrogen pipeline IV; 191. Slag slurry process I; 192. Slag slurry process II; 20. Flushing clear liquid pipeline; 21. Condensate tank; 22. Drainage liquid tank; 23. Vent; 24. Nitrogen pipeline III; 25. Drainage liquid pipeline; 26. Vent pipeline IV. DETAILED DESCRIPTION

[0063] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0064] Example 1 This embodiment provides a Figure 1The polysilicon distillation process control system shown comprises a 6-stage distillation tower, wherein the top outlet of the distillation tower is connected to a reflux tank 7, the distillation tower kettle is provided with a heat exchanger 8, the bottom of the reflux tank 7 is connected to a reflux pump 9, the reflux outlet of the reflux pump 9 is connected to the top of the distillation tower of this stage, the top of the distillation tower is provided with a tail gas discharge pipe 10, the tail gas discharge pipe 10 is connected to a tail gas condensing device, the outlet of the reflux pump 9 of the first-stage tower 1 is connected to the feed inlet of the second-stage tower 2, the outlet of the reflux pump 9 of the second-stage tower 2 is connected to the anti-disproportionation device 12, the outlet of the reflux pump 9 of the third-stage tower 3 is connected to the feed inlet of the fourth-stage tower 4, the outlet of the reflux pump 9 of the fourth-stage tower 4 is connected to the feed inlet of the fourth-stage tower 4, and the outlet of the reflux pump 9 of the fourth-stage tower 4 is connected to the feed inlet of the fourth-stage tower 4. The extraction outlet of the flow pump 9 is connected to the raw material tank 13, the extraction outlet of the reflux pump 9 of the 5-stage tower 5 is connected to the trichlorosilane refined material tank 14, and the extraction outlet of the reflux pump 9 of the 6-stage tower 6 is connected to the silicon tetrachloride storage tank 15; the feed port of the 1-stage tower 1 is connected to the raw material tank 13, and the tower bottom discharge port of the 1-stage tower 1 is connected to the feed port of the 6-stage tower 6; the tower bottom discharge port of the 2-stage tower 2 is connected to the feed port of the 3-stage tower 3, and the tower bottom discharge port of the 3-stage tower 3 is connected to the raw material tank 13; the tower bottom discharge port of the 4-stage tower 4 is connected to the feed port of the 5-stage tower 5, the tower bottom discharge port of the 5-stage tower 5 is connected to the raw material tank 13, and the tower bottom discharge port of the 6-stage tower 6 is connected to the slag mixing tank 16; The outlet of the tail gas discharge pipe 10 of the distillation tower is provided with a venting regulating valve II, the top of the distillation tower is provided with a pressure sensor II, the reflux tank 7 is provided with a liquid level gauge IIa, the distillation tower kettle is provided with a liquid level gauge IIb, and the distillation tower kettle outlet is provided with a flow meter IIb and a tower kettle extraction regulating valve IIa; The reflux outlet of the reflux pump 9 is provided with a reflux regulating valve II and a flow meter IIc; the production outlet of the reflux pump 9 is provided with a tower top production regulating valve IIb and a flow meter IId; The distillation tower is provided with a temperature sensor IIa at the top, a temperature sensor IIb at the bottom, and a temperature sensor IIc in the tower; The heating medium pipelines of the heat exchangers 8 of the 1st tower 1, the 3rd tower 3 and the 6th tower 6 are connected to the steam main pipeline 17 and heated by steam; the top outlets of the 3rd tower 3, the 5th tower 5 and the 6th tower 6 are respectively connected to the inlet of the heating medium pipeline of the upper distillation tower heat exchanger 8, and the inlets of the reflux tanks 7 of the 3rd tower 3, the 5th tower 5 and the 6th tower 6 are respectively connected to the outlet of the heating medium pipeline of the upper distillation tower heat exchanger 8, and the 2nd tower 2, the 4th tower 4 and the 5th tower 5 are heated by the material temperature of the lower distillation tower instead of directly using steam, so as to achieve energy saving; The heating medium inlet of the heat exchanger 8 of the distillation tower is provided with a heating medium regulating valve and a temperature sensor IId, and the steam main pipeline 17 is provided with a pressure sensor I; the heating medium pipeline inlet of the heat exchanger 8 of the 1st-level tower 1, the 3rd-level tower 3 and the 6th-level tower 6 is provided with a flow meter IIa; The feed inlet of the first-stage tower 1 is provided with a feed regulating valve 1 and a flow meter 1b, and the raw material tank 13 is provided with a liquid level meter 1.

[0065] This embodiment also provides a control method for the above control system, including: distillation tower top vent flow control, reflux flow control, tower top extraction flow control, tower bottom extraction flow control and tower bottom temperature control.

[0066] The venting pressure control of the distillation tower top includes: automatic control of the tower top venting regulating valve II and the tower top pressure single loop, and the PID loop action form is positive action; setting the tower top control pressure, monitoring the tower top pressure value in real time through the pressure sensor II, when there is a positive deviation between the tower top real-time pressure value and the set pressure value, the venting regulating valve II increases the output opening and automatically adjusts the pressure value; when there is a negative deviation between the tower top real-time pressure value and the set pressure value, the venting regulating valve II reduces the output opening and automatically adjusts the pressure value; so that the tower top pressure value of the distillation tower is basically stably maintained at the set value.

[0067] The distillation tower reflux flow control comprises: (1) The reflux regulating valve II of the first-stage tower 1 and the reflux flow rate are automatically controlled in a single loop; the reflux flow rate is set, and the reflux flow rate of the distillation tower is monitored in real time by the flow meter IIc at the reflux outlet of the reflux pump 9 of the first-stage tower 1. When there is a positive deviation between the real-time reflux flow rate value and the set reflux flow rate value, the reflux regulating valve II reduces the output opening and automatically adjusts the reflux flow rate value; when there is a negative deviation between the real-time reflux flow rate value and the set reflux flow rate value, the reflux regulating valve II increases the output opening and automatically adjusts the reflux flow rate value; so that the reflux flow rate value of the distillation tower is basically stable and maintained at the set value.

[0068] (2) The reflux regulating valve Ⅱ of the second-stage tower 2 is controlled in cascade with the reflux flow rate Ⅱc and the tower top temperature Ⅱa; the tower top temperature control is the main loop, and the PID loop action form is positive action; the tower top control temperature is set, and the tower top temperature value is monitored in real time through the temperature sensor Ⅱa. When there is a positive deviation between the real-time tower top temperature value and the set temperature value, the reflux flow rate Ⅱc output is increased to automatically adjust the temperature value; when there is a negative deviation between the real-time tower top temperature value and the set temperature value, the reflux flow rate Ⅱc output is reduced to automatically adjust the temperature value; so that the tower top temperature value of the distillation tower is basically stable and maintained at the set value; the reflux flow The quantity control is the secondary loop, and the PID loop action form is the reverse action; the reflux flow output of the temperature control main loop is used as the set reflux flow, and the reflux flow of the distillation tower is monitored in real time by the flow meter Ⅱc at the reflux outlet of the reflux pump 9 of the second-stage tower 2. When there is a positive deviation between the real-time reflux flow value and the set reflux flow value, the reflux regulating valve Ⅱ reduces the output opening and automatically adjusts the reflux flow value; when there is a negative deviation between the real-time reflux flow value and the set reflux flow value, the reflux regulating valve Ⅱ increases the output opening and automatically adjusts the reflux flow value; so that the reflux flow value of the distillation tower is basically stable and maintained at the set value.

[0069] (3) The reflux regulating valve Ⅱ of the 3-stage tower 3, the 5-stage tower 5 and the 6-stage tower 6 are controlled in cascade with the tower bottom liquid level Ⅱb and the reflux flow Ⅱc; the tower bottom liquid level control is the main loop, and the PID loop action form is the reverse action; the tower bottom control liquid level is set, and the tower bottom liquid level value is monitored in real time by the liquid level meter Ⅱb. When there is a positive deviation between the real-time tower bottom liquid level value and the set liquid level value, the reflux flow Ⅱc output is reduced to automatically adjust the liquid level value; when there is a negative deviation between the real-time tower bottom liquid level value and the set liquid level value, the reflux flow Ⅱc output is increased to automatically adjust the liquid level value; so that the tower bottom liquid level value of the distillation tower is basically stable and maintained at the set value. The reflux flow control is a secondary loop, and the PID loop action form is a reverse action; the reflux flow output of the tower bottom liquid level control main loop is used as the set reflux flow, and the reflux flow of the distillation tower is monitored in real time by the flow meter Ⅱc at the reflux outlet of the reflux pump 9. When there is a positive deviation between the real-time reflux flow value and the set reflux flow value, the reflux regulating valve Ⅱ reduces the output opening and automatically adjusts the reflux flow value; when there is a negative deviation between the real-time reflux flow value and the set reflux flow value, the reflux regulating valve Ⅱ increases the output opening and automatically adjusts the reflux flow value; so that the reflux flow value of the distillation tower is basically stable and maintained at the set value.

[0070] (4) The reflux regulating valve Ⅱ of the 4-stage tower 4 is controlled in series with the reflux tank 7 liquid level Ⅱa and the reflux flow Ⅱc; the reflux tank 7 liquid level control is the main loop, and the PID loop action form is positive action; the reflux tank 7 control liquid level is set, and the reflux tank 7 liquid level value is monitored in real time by the liquid level meter Ⅱa. When there is a positive deviation between the real-time liquid level value of the reflux tank 7 and the set liquid level value, the reflux flow Ⅱc output is increased to automatically adjust the liquid level value; when there is a negative deviation between the real-time liquid level value of the reflux tank 7 and the set liquid level value, the reflux flow Ⅱc output is reduced to automatically adjust the liquid level value; so that the liquid level value of the reflux tank 7 of the 4-stage distillation tower is basically stable and maintained at the set value. The reflux flow control is a secondary loop, and the PID loop action form is a reverse action; the reflux flow output of the reflux tank 7 liquid level control main loop is used as the set reflux flow, and the reflux flow of the distillation tower is monitored in real time by the flow meter Ⅱc at the reflux outlet of the reflux pump 9. When there is a positive deviation between the real-time reflux flow value and the set reflux flow value, the reflux regulating valve Ⅱ reduces the output opening and automatically adjusts the reflux flow value; when there is a negative deviation between the real-time reflux flow value and the set reflux flow value, the reflux regulating valve Ⅱ increases the output opening and automatically adjusts the reflux flow value; so that the reflux flow value of the distillation tower is basically stable and maintained at the set value.

[0071] The top extraction flow control includes: (1) The top extraction regulating valve Ⅱb of the 1st-stage tower 1, the 3rd-stage tower 3 and the 6th-stage tower 6 are controlled in series with the liquid level Ⅱa of the reflux tank 7 and the top extraction flow Ⅱd; the liquid level control of the reflux tank 7 is the main loop, and the PID loop action form is positive action; the control liquid level of the reflux tank 7 is set, and the liquid level value of the reflux tank 7 is monitored in real time by the liquid level meter Ⅱa. When there is a positive deviation between the real-time liquid level value of the reflux tank 7 and the set liquid level value, the top extraction flow Ⅱd is increased to output and automatically adjust the liquid level value; when there is a negative deviation between the real-time liquid level value of the reflux tank 7 and the set liquid level value, the top extraction flow Ⅱd is reduced to output and automatically adjust the liquid level value; so that the liquid level value of the reflux tank 7 of the distillation tower is basically stable and maintained at the set value. The top extraction flow control is a secondary loop, and the PID loop action form is a reaction; the top extraction flow output of the main loop of the reflux tank 7 liquid level control is used as the set extraction flow, and the top extraction flow of the distillation tower is monitored in real time through the top extraction flow meter Ⅱd. When there is a positive deviation between the real-time extraction flow value and the set extraction flow value, the top extraction regulating valve Ⅱb reduces the output opening to automatically adjust the top extraction flow value; when there is a negative deviation between the real-time extraction flow value and the set extraction flow value, the top extraction regulating valve Ⅱb increases the output opening to automatically adjust the top extraction flow value; so that the top extraction flow value of the distillation tower is basically stable and maintained at the set value.

[0072] (2) The top extraction regulating valve Ⅱb of the second-stage tower 2 and the liquid level Ⅱa of the reflux tank 7 are automatically controlled in a single loop, and the PID loop action form is positive action. Set the control liquid level of the reflux tank 7, and monitor the liquid level value of the reflux tank 7 in real time through the liquid level meter Ⅱa. When there is a positive deviation between the real-time liquid level value of the reflux tank 7 and the set liquid level value, increase the output opening of the top extraction regulating valve Ⅱb to automatically adjust the liquid level value; when there is a negative deviation between the real-time liquid level value of the reflux tank 7 and the set liquid level value, reduce the output opening of the top extraction regulating valve Ⅱb to automatically adjust the liquid level value; so that the liquid level value of the reflux tank 7 of the distillation tower is basically stable and maintained at the set value.

[0073] (3) The top extraction regulating valve Ⅱb and the top extraction flow Ⅱd of the 4-stage tower 4 and the 5-stage tower 5 are automatically controlled by a single loop, and the PID loop action form is reverse action. The top extraction flow is set, and the top extraction flow of the distillation tower is monitored in real time through the top extraction flow meter Ⅱd. When there is a positive deviation between the real-time extraction flow value and the set extraction flow value, the top extraction regulating valve Ⅱb reduces the output opening to automatically adjust the top extraction flow value; when there is a negative deviation between the real-time extraction flow value and the set extraction flow value, the top extraction regulating valve Ⅱb increases the output opening to automatically adjust the top extraction flow value; so that the top extraction flow value of the distillation tower is basically stable and maintained at the set value.

[0074] The tower bottom extraction flow control includes: (1) The bottom extraction regulating valve Ⅱa of the first-stage tower 1, the second-stage tower 2 and the fourth-stage tower 4 are controlled in cascade with the bottom liquid level Ⅱb and the bottom extraction flow Ⅱb; the bottom liquid level control is the main loop, and the PID loop action form is positive action; the bottom liquid level is set, and the bottom liquid level value is monitored in real time by the liquid level meter Ⅱb. When there is a positive deviation between the real-time bottom liquid level value and the set liquid level value, the bottom extraction flow Ⅱb output is increased to automatically adjust the liquid level value; when there is a negative deviation between the real-time bottom liquid level value and the set liquid level value, the bottom extraction flow Ⅱb output is reduced to automatically adjust the liquid level value; so that the bottom liquid level value of the distillation tower is basically stable and maintained at the set value. The tower bottom extraction flow control is a secondary loop, and the PID loop action form is a reaction; the tower bottom extraction flow output of the tower bottom liquid level control main loop is used as the set extraction flow, and the tower bottom extraction flow of the distillation tower is monitored in real time through the tower bottom extraction flow meter Ⅱb. When there is a positive deviation between the real-time extraction flow value and the set extraction flow value, the tower bottom extraction regulating valve Ⅱa reduces the output opening to automatically adjust the tower bottom extraction flow value; when there is a negative deviation between the real-time extraction flow value and the set extraction flow value, the tower bottom extraction regulating valve Ⅱa increases the output opening to automatically adjust the tower bottom extraction flow value; so that the tower bottom extraction flow value of the distillation tower is basically stable and maintained at the set value.

[0075] (2) The kettle extraction regulating valve Ⅱa and kettle extraction flow Ⅱb of the 3-stage tower 3 and the 5-stage tower 5 are automatically controlled in a single loop, and the PID loop action form is reverse action. The kettle extraction flow is set, and the kettle extraction flow of the distillation tower is monitored in real time through the kettle extraction flow meter Ⅱb. When there is a positive deviation between the real-time extraction flow value and the set extraction flow value, the kettle extraction regulating valve Ⅱa reduces the output opening to automatically adjust the kettle extraction flow value; when there is a negative deviation between the real-time extraction flow value and the set extraction flow value, the kettle extraction regulating valve Ⅱa increases the output opening to automatically adjust the kettle extraction flow value; so that the kettle extraction flow value of the distillation tower is basically stable and maintained at the set value.

[0076] The temperature control of the tower includes: (1) The heating medium regulating valve and the tower kettle temperature Ⅱb of the 1st stage tower 1 and the 3rd stage tower 3 are automatically controlled by a single loop, and the PID loop action form is reverse action; the tower kettle control temperature is set, and the tower kettle temperature value is monitored in real time by the temperature sensor Ⅱb. When there is a positive deviation between the real-time tower kettle temperature value and the set temperature value, the heating medium regulating valve reduces the output opening and automatically adjusts the temperature value; when there is a negative deviation between the real-time tower kettle temperature value and the set temperature value, the heating medium regulating valve increases the output opening and automatically adjusts the temperature value; so that the tower kettle temperature value of the distillation tower is basically stable and maintained at the set value.

[0077] (2) The heating medium regulating valve of the 6-stage tower 6 is controlled in series with the steam flow IIa and the tower kettle temperature IIb. The tower kettle temperature control is the main loop, and the PID loop is in the reverse action mode. The tower kettle control temperature is set, and the tower kettle temperature value is monitored in real time through the temperature sensor IIb. When there is a positive deviation between the real-time tower kettle temperature value and the set temperature value, the steam flow IIa output is reduced to automatically adjust the temperature value; when there is a negative deviation between the real-time tower kettle temperature value and the set temperature value, the steam flow IIa output is increased to automatically adjust the temperature value; so that the tower kettle temperature value of the distillation tower is basically stable and maintained at the set value. Steam flow control is the secondary loop, and the PID loop is in the reverse action mode. The steam flow output of the tower kettle temperature control main loop is used as the set flow, and the steam flow of the distillation tower is monitored in real time through the steam flow meter IIa. When there is a positive deviation between the real-time steam flow value and the set steam flow value, the heating medium regulating valve reduces the output opening and automatically adjusts the steam flow value; when there is a negative deviation between the real-time steam flow value and the set steam flow value, the heating medium regulating valve increases the output opening and automatically adjusts the steam flow value; so that the steam flow value of the distillation tower is basically stable and maintained at the set value.

[0078] The first-stage tower 1, the third-stage tower 3 and the sixth-stage tower 6 also include steam automatic adjustment control, including the following steps: S101: Setting parameters: setting sampling time, triggering time, steam main set pressure difference PI-SP and heating medium regulating valve opening adjustment set value OUT-SP; S102: monitor the pressure in the steam main in real time through the pressure sensor 1, and calculate the average value of the previous 6 sampling pressures; S103: Calculate the difference between the current pressure of the steam main and the average pressure of the steam main, and set judgment condition 1 and judgment condition 2; The judgment condition 1 is: the difference between the current pressure of the steam main and the average pressure of the steam main is greater than or equal to the set pressure difference PI-SP of the steam main; The judgment condition 2 is: when the difference between the current pressure of the steam main and the average pressure of the steam main is less than the set pressure difference PI-SP of the steam main; S104: When neither condition 1 nor condition 2 is satisfied, continue to make real-time judgment; When condition 1 is met within T2 consecutive times, the heating medium regulating valve loop mode is switched to manual, and the valve opening is reduced to OUT-SP; after stabilization for 2S, the heating medium regulating valve loop mode is switched to automatic, and the last automatic mode flow setting value is restored; When condition 2 is met within the continuous T2 time, the heating medium regulating valve circuit mode is switched to manual, and the valve opening is widened OUT-SP; after stabilizing for 2S, the heating medium regulating valve circuit mode is switched to automatic, and the last automatic mode flow setting value is restored.

[0079] In this embodiment, since the steam main pressure fluctuates greatly, the average value of the sampling pressure is used for judgment; the heating medium regulating valve loop controls the temperature of the distillation tower kettle, and the temperature hysteresis is large. The opening of the heating medium regulating valve is adjusted in advance according to the changes in the steam main pressure to avoid fluctuations in the distillation tower kettle temperature, thereby affecting product quality.

[0080] The first-stage tower 1 also includes automatic feed control: the feed amount of the first-stage tower 1 is automatically adjusted according to the liquid level of the raw material tank 13, so as to realize automatic control and stable regulation of the feed amount; The automatic feeding control comprises: S201: Setting parameters: Setting the feed set value adjustment interval of the PID loop of the feed regulating valve I; Setting the upper and lower limits of the feed flow set value in the automatic mode of the PID loop of the feed regulating valve I; Setting the upper and lower limits, upper and lower limits of the liquid level of the raw material tank 13; S202: Feed regulating valve I and feed flow rate are automatically controlled in a single loop, and the PID loop action form is a reaction; the feed flow rate of the distillation tower is monitored in real time by flow meter Ib, and when there is a positive deviation between the real-time feed flow rate value and the set flow rate value, the feed regulating valve I reduces the output opening to automatically adjust the feed flow rate value; when there is a negative deviation between the real-time feed flow rate value and the set flow rate value, the feed regulating valve I increases the output opening to automatically adjust the feed flow rate value; when it is necessary to reduce the output opening of the feed regulating valve I and the feed flow rate set value reaches the lower limit, no adjustment is made; when it is necessary to increase the output opening of the feed regulating valve I and the feed flow rate set value reaches the upper limit, no adjustment is made; so that the feed flow rate value of the distillation tower is basically stable and maintained at the set value; S203: When the liquid level of the raw material tank 13 is ≥ the upper limit, and the liquid level is < the upper and lower limits, the feed flow setting value of the feed regulating valve I PID loop is increased by SP1; after adjustment, after the adjustment interval time, the program continues to make real-time judgments; S204: When the liquid level of the raw material tank 13 is greater than the lower limit and the liquid level is less than or equal to the lower limit, the feed flow setting value of the feed regulating valve I PID loop is reduced by SP1; after adjustment, after the adjustment interval time, the program continues to make real-time judgments; S205: When the liquid level of the raw material tank 13 is ≥ the upper limit, the feed flow setting value of the feed regulating valve I PID loop is increased by SP2; after adjustment, after the adjustment interval time, the program continues to make real-time judgments; S206: When the liquid level of the raw material tank 13 is ≤ the lower limit, the feed flow setting value of the feed regulating valve I PID loop is reduced by SP2; after adjustment, after the adjustment interval time, the program continues to make real-time judgments.

[0081] In this embodiment, the liquid level of the raw material tank 13 is periodically determined according to the set conditions and the set time, and the set value of the loop flow of the feed regulating valve I of the first-stage distillation tower is automatically adjusted to maintain the stability of the feed amount, prevent over-adjustment, ensure the stability of the distillation tower parameters, and avoid quality deviation.

[0082] The first-stage tower 1 also includes automatic temperature control in the tower, including the following steps: S301: Setting parameters: Setting the temperature setting value adjustment interval of the heating medium regulating valve PID loop; Setting the upper and lower limits of the temperature setting value in the automatic mode of the heating medium regulating valve PID loop; Setting the upper upper limit, upper limit, lower lower limit and lower limit of the medium temperature of the first stage tower 1; S302: When the medium temperature of the first tower 1 is ≥ the upper limit, and the medium temperature is < the upper and lower limits, the temperature setting value of the heating medium regulating valve PID loop is increased by SP1; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments; S303: When the medium temperature of the first stage tower 1 is greater than the lower limit, and the medium temperature is less than or equal to the lower limit, the temperature setting value of the heating medium regulating valve PID loop is reduced by SP1; after adjustment, after the adjustment interval time, the program continues to make real-time judgments; S304: When the medium temperature of the first stage tower 1 is ≥ the upper limit, the temperature setting value of the heating medium regulating valve PID loop is increased by SP2; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments; S305: When the temperature in the first-stage tower 1 is ≤ the lower limit, the temperature setting value of the heating medium regulating valve PID loop is reduced by SP2; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments.

[0083] In this embodiment, according to the temperature change in the first-stage distillation tower, the temperature setting value of the heating medium regulating valve loop of the first-stage distillation tower is automatically adjusted, and the single temperature variable control is changed to the dual variable control of the tower bottom temperature and the tower temperature, which can better match the change of the feed amount, stabilize the distillation tower temperature, and ensure product quality.

[0084] The distillation tower also includes an automatic reflux ratio adjustment control, which automatically adjusts the reflux ratio according to the extraction flow rate at the top of the distillation tower to ensure the stability of the reflux of the distillation tower, ensure the distillation effect, and reduce energy consumption; including: S401: input the set value of the reflux ratio (ratio of reflux flow rate to tower top production flow rate); S402: The flow setting value of the reflux regulating valve II of the distillation tower is automatically adjusted to the product of the reflux ratio setting value and the tower top extraction flow rate; S403: The PID control loop of the reflux regulating valve II acts in a reverse manner; the real-time value of the top tower reflux flow is monitored in real time by the flow meter IIc. When there is a positive deviation between the real-time value of the reflux flow and the set value of the reflux flow, the reflux regulating valve II reduces the output opening to automatically adjust the reflux flow; when there is a negative deviation between the real-time value of the reflux flow and the set value of the reflux flow, the reflux regulating valve II increases the output opening to automatically adjust the reflux flow; so that the reflux flow value of the distillation tower is basically stable and maintained at the set value.

[0085] In this embodiment, the first-stage tower 1 is a separation tower, which separates the heavy component (silicon tetrachloride). The product liquid of the trichlorosilane synthesis and cold hydrogenation process enters the raw material tank 13, and is transported by a pump into the first-stage synthetic distillation tower 1 for separation. The trichlorosilane and dichlorosilane are extracted from the top of the tower and enter the second-stage synthetic distillation tower 2; the silicon tetrachloride is extracted from the bottom of the tower and enters the sixth-stage synthetic distillation tower 6.

[0086] The second-stage tower 2 is a light-removal tower, which removes dichlorosilane. The trichlorosilane and dichlorosilane produced from the top of the synthetic distillation first-stage tower 1 enter the synthetic distillation second-stage tower 2 to remove light components, and the dichlorosilane produced from the top of the tower is subjected to the anti-disproportionation process; the trichlorosilane produced from the bottom of the tower enters the synthetic distillation third-stage tower 3.

[0087] The 3rd stage tower 3 is a de-heaving tower, which removes heavy metal impurities (silicon powder, iron, aluminum, boron, phosphorus, etc.). The trichlorosilane extracted from the bottom of the synthetic distillation 2nd stage tower 2 enters the synthetic distillation 3rd stage tower 3 to remove heavy components, and the trichlorosilane extracted from the top of the tower enters the synthetic distillation 4th stage tower 4, and the heavy components extracted from the bottom of the tower are sent to the raw material tank 13.

[0088] The 4-stage tower 4 is a light-removal tower, which removes light impurities (boron, phosphorus, etc.). The trichlorosilane extracted from the top of the synthetic distillation 3-stage tower 3 enters the synthetic distillation 4-stage tower 4 to remove light components, and the light components extracted from the top are sent to the raw material tank 13; the trichlorosilane extracted from the bottom of the tower enters the synthetic distillation 5-stage tower 5.

[0089] The 5-stage tower 5 is a de-heaving tower, which removes heavy metal impurities (silicon powder, iron, aluminum, boron, phosphorus, etc.). The trichlorosilane extracted from the bottom of the synthetic distillation 4-stage tower 4 enters the synthetic distillation 5-stage tower 5 to remove the heavy components again, and the refined trichlorosilane extracted from the top of the tower is sent to the refined material tank in the tank area as the raw material for the reduction process for production; the heavy components extracted from the bottom of the tower enter the raw material tank 13.

[0090] The 6-stage tower 6 is a silicon tetrachloride removal tower to remove high-boiling silicon tetrachloride. The silicon tetrachloride extracted from the bottom of the synthetic distillation 1-stage tower 1 enters the synthetic distillation 6-stage tower 6 to remove high-boiling silicon tetrachloride. The silicon tetrachloride that meets the product quality requirements is extracted from the top of the tower and enters the silicon tetrachloride storage tank 15 for use in the cold hydrogenation and anti-disproportionation processes; the heavy components and metal impurities extracted from the bottom of the tower enter the slag mixing tank 16.

[0091] The top pressure sensors Ⅱ of the 1st to 6th stage distillation towers all adopt EJA pressure transmitter 2"-150LB, the venting control valves Ⅱ all adopt German Aka bellows control valves 1"-150LB, the reflux tank 7 level gauges Ⅱa all adopt EJA differential pressure transmitters 2"-150LB, and the tower bottom level gauges Ⅱb all adopt EJA differential pressure transmitters 2"-150LB. The discharge flow meter Ⅱb of the 1st stage tower 1 bottom adopts E+H mass flowmeter, and the discharge flow meter Ⅱb of the 2nd to 6th stage tower 6 bottom adopts Yokogawa vortex flowmeter. The 1st stage tower 1 bottom production control valve Ⅱa adopts German Aka bellows control valve 6"-150LB, the 2nd and 4th stage tower 4 bottom production control valves Ⅱa adopt Samson bellows control valve DN100 PN40, and the 3rd and 5th stage tower 5 bottom production control valve Ⅱa adopts German Aka bellows control valve 1 / 2"-150LB.

[0092] The reflux regulating valves Ⅱ of level 1 tower 1, level 4 tower 4, level 5 tower 5 and level 6 tower 6 all adopt German Aka bellows regulating valve 8"-150LB, and the reflux regulating valves Ⅱ of level 2 tower 2 and level 3 tower 3 all adopt German Aka bellows regulating valve 6"-150LB. The reflux flowmeters Ⅱc of level 1 to 6 distillation towers all adopt Yokogawa vortex flowmeters. The top production regulating valves Ⅱb of level 1 tower 1, level 2 tower 2, level 3 tower 3 and level 5 tower 5 all adopt Samson bellows regulating valve DN100 PN40, the top production regulating valves Ⅱb of level 4 tower 4 adopt German Aka bellows regulating valve 1"-150LB, and the top production regulating valves Ⅱb of level 6 tower 6 adopt German Aka bellows regulating valve 6"-150LB. The top production flowmeter Ⅱd of 1st-stage tower 1, 3rd-stage tower 3 and 4th-stage tower 4 all adopt Yokogawa vortex flowmeter, and the top production flowmeter Ⅱd of 2nd-stage tower 2, 5th-stage tower 5 and 6th-stage tower 6 all adopt E+H mass flowmeter.

[0093] The top temperature sensor Ⅱa, bottom temperature sensor Ⅱb and mid-tower temperature sensor Ⅱc of 1~6 distillation towers all use Zhonghuan integrated temperature transmitters.

[0094] The heating medium regulating valves of the heat exchangers 8 of the 1st to 6th stage distillation towers all adopt Sichuan Instrument regulating valves, and the temperature sensors Ⅱd all adopt Zhonghuan integrated temperature transmitters. The pressure sensor I of the steam main pipeline 17 adopts EJA pressure transmitter. The flowmeters Ⅱa of the heat exchangers 8 of the 1st stage tower 1, the 3rd stage tower 3 and the 6th stage tower 6 all adopt Rosemount Annubar flowmeters.

[0095] The feed regulating valve I of the first-stage tower 1 adopts the German Aka bellows regulating valve 6"-150LB, and the flow meter Ib adopts the E+H mass flow meter. The liquid level meter I of the raw material tank 13 adopts the Honeywell differential pressure transmitter 2"-150LB.

[0096] Example 2 The difference between this embodiment and embodiment 1 is that, in this embodiment, Figure 4 As shown, There are two slag mixing tanks 16, each of which is connected to a nitrogen pipeline IV 18, and each of which is provided with a nitrogen shut-off valve IV. The slag mixing tank 16 is respectively provided with a venting pipeline IV26, and the venting pipeline IV26 is respectively provided with a venting shut-off valve IV; The connecting pipelines between the slag mixing tank 16 and the kettle of the 6th stage tower 6 are respectively provided with a feed cut-off valve IVa; The discharge port of each slag mixing tank 16 is connected to the slag slurry process I191 and the slag slurry process II192 respectively, and the connecting pipeline between the discharge port of the slag mixing tank 16 and the slurry process is provided with a feed cut-off valve IV; The connecting pipelines of the slag material mixing tank 16 with the slag slurry process I 191 and the slag slurry process II 192 are respectively provided with a discharge cut-off valve IV; The slurry process I191 and the slurry process II192 are respectively provided with two receiving tanks, and the feed inlets of the receiving tanks are provided with feed cut-off valves IVb; The discharge ports of the slag mixing tank 16 are respectively connected to flushing liquid pipelines 20, and flushing shut-off valves IV are respectively provided on the flushing liquid pipelines 20; The slag mixing tank 16 is provided with a liquid level meter IV, a pressure sensor IV and a temperature sensor IV; the remaining structures are the same as those in the first embodiment.

[0097] The control method in this embodiment also includes the following steps: The 6-stage tower 6 also includes automatic slag discharge control for the tower bottom, and automatic timed slag discharge for the tower bottom to prevent high-boiling materials from accumulating in the tower bottom, causing blockage of the tower bottom, wear of the reboiler, and the risk of material leakage, including: S501: respectively set the material receiving amounts of the two slag mixing tanks 16.

[0098] S502: judging the slag discharge conditions of the 6-stage distillation tower 6, including: when the liquid level of one of the slag mixing tanks 16 is less than 54%, the pressure is less than 0.2 MPa, and the venting shut-off valve IV is in an open state, the slag mixing tank 16 is discharged and fed; when both slag mixing tanks 16 meet the above conditions, the slag mixing tank 16 with a higher liquid level is discharged and fed; when both slag mixing tanks 16 do not meet the above conditions, waiting for the slag mixing tank 16 to meet the material receiving conditions; S503: When one of the slag mixing tanks 16 meets the conditions described in S502, the nitrogen shut-off valve IV of the slag mixing tank 16 that meets the slag discharge conditions is closed, the vent shut-off valve IV of the slag mixing tank 16 that meets the slag discharge conditions is opened, the feed shut-off valve IVa of the slag mixing tank 16 that does not meet the slag discharge conditions is closed, and the timing RET1 is started; After the above-mentioned cut-off valve is fed back to the right position, the feed cut-off valve IVa of the slag mixing tank 16 that meets the slag discharge conditions is opened, and the timing RET2 is started; When the liquid level of the slag mixing tank 16 that meets the slag discharge conditions rises by more than the set material receiving amount, the feed cut-off valve IVa of the mixing tank is closed; When RET2 counts down to 30 minutes, and the feed shut-off valve of the slag mixing tank 16 that meets the slag discharge conditions is not closed and is still feeding, it will be prompted: Distillation 6-stage tower 6 slag discharge has timed out, please confirm.

[0099] S504: When the RET1 timing reaches 160 minutes, steps S502-S503 are repeated. When both slag mixing tanks 16 do not meet the material receiving conditions, the circulation conditions are not met, and it is prompted that the slag discharge conditions of the 6-stage tower 6 are not met.

[0100] In this embodiment, S502 determines whether the slag discharge condition of the 6-stage distillation tower 6 is met; If the slag discharge conditions are met in S503, the nitrogen shut-off valve IV of the slag mixing tank 16 that meets the slag discharge conditions needs to be closed to prevent the pressure of the slag mixing tank 16 from being higher than the pressure of the distillation 6-stage tower 6, which would cause the slag to flow back; the vent shut-off valve IV of the slag mixing tank 16 that meets the slag discharge conditions is opened to prevent the slag mixing tank 16 from being over-pressurized during the material collection process; the RET1 timing is the cycle period for the normal operation of the slag discharge; the RET2 timing is to remind the main control distillation 6-stage tower 6 that the slag discharge is timed out and the pipeline is blocked.

[0101] The slag mixing tank 16 includes automatic discharge control, including the following steps: S601: setting the discharge amount of the two slag mixing tanks 16 respectively; S602: Determine the discharge conditions of the slag mixing tank 16: When the liquid level of one of the slag mixing tanks 16 is greater than 65% and the liquid level of the other slag mixing tank 16 is less than or equal to 65%, the slag mixing tank 16 with a liquid level greater than 65% discharges the material; When the liquid levels of the two slag mixing tanks 16 are both greater than 65%, the slag mixing tank 16 with a higher liquid level will discharge the material; When the liquid levels of the two slag mixing tanks 16 are both ≤65%, the slag mixing tank 16 with a liquid level of >54% will discharge the material; When the liquid levels of the two slag mixing tanks 16 are both ≤65%, and when the liquid levels of the two slag mixing tanks 16 are both >54%, the slag mixing tank 16 with the higher liquid level will discharge the material; When the liquid levels of the two slag mixing tanks 16 are both ≤65%, and when the liquid levels of the two slag mixing tanks 16 are both ≤54%, the liquid level conditions are re-judged; S603: Determine the slag material mixing tank 16 for discharging according to the discharging conditions in step S602, and close the venting cut-off valve IV and the feed cut-off valve IVa of the discharging slag material mixing tank 16; S604: monitor the pressure in the slag mixing tank 16 of the discharge material in real time through the pressure sensor IV. When the pressure is ≥0.6MPa, execute the next step; when the pressure is <0.6MPa, open the nitrogen cut-off valve IV of the slag mixing tank 16 of the discharge material, charge the pressure to 0.6MPa, close the nitrogen cut-off valve IV, and execute the next step; S605: Determine the discharge path: by default, start from the slurry process I191 to confirm the discharge conditions each time; Material collection conditions of slurry process I: the feed cut-off valve IVb of the two material collection tanks of the feed process I meets an open state, the discharge cut-off valve IV between the discharge slag mixing tank 16 and the slurry process II 192 is closed, and the discharge cut-off valve IV between the discharge slag mixing tank 16 and the slurry process I 191 is opened; Material receiving conditions of slurry process II: the feed cut-off valve IVb of the two material receiving tanks of the feed process II meets an open state, the discharge cut-off valve IV between the discharge slag mixing tank 16 and the slurry process I191 is closed, and the discharge cut-off valve IV between the discharge slag mixing tank 16 and the slurry process II192 is opened; S606: Start discharging. When the discharging amount of the slag material mixing tank 16 is greater than the set value or the liquid level in the slag material mixing tank 16 is less than 15%, close the discharging cut-off valve IV and the nitrogen cut-off valve IV of the slag material mixing tank 16; S607: After closing the discharge cut-off valve IV and the nitrogen cut-off valve IV, open the clear liquid cut-off valve of the discharge slag mixing tank 16 for flushing, and start timing; when the 300s timing is up, close the clear liquid cut-off valve IV of the discharge slag mixing tank 16, and open the venting cut-off valve IV; S608: During the discharging process, the pressure of the slag mixing tank 16 is maintained between 0.55 and 0.6 MPa. During the discharging process, if the feed cut-off valves IVb of the two receiving tanks of the slurry process I191 or the slurry process II192 are both closed, an alarm will be triggered. After confirmation by the main control, the discharging path will be confirmed again. During the discharging process, if the feed cut-off valves IVb of the two receiving tanks of any slurry process are both closed, an alarm will be triggered.

[0102] In this embodiment, the synthetic distillation 6-stage tower 6 is a silicon tetrachloride removal tower to remove high-boiling silicon tetrachloride products. The tower kettle regularly extracts heavy components and metal impurities to prevent high-boiling products from accumulating in the tower kettle, causing blockage of the tower kettle, wear of the reboiler, and the risk of material leakage. The heavy components and metal impurities extracted from the tower kettle enter the slag stirring tank 16 for stirring to maintain the fluidity and temperature of the high-boiling products and prevent them from solidifying and clogging the pipeline, and finally send them to the slag slurry process for processing and recycling.

[0103] In this embodiment, the nitrogen cut-off valve IV of the slag mixing tank 16 adopts a KTM pneumatic cut-off valve; The slag mixing tank 16 venting cut-off valve IV adopts Suk pneumatic cut-off valve; The feed cut-off valve IVa of the slag mixing tank 16 adopts Suk pneumatic cut-off valve 2"-150LB; The slag mixing tank 16 feeding cut-off valve IV adopts Suk pneumatic cut-off valve 2"-150LB; The connecting pipelines between the slag mixing tank 16 and the slag slurry process I 191 and the slag slurry process II 192 are respectively provided with a discharge cut-off valve IV, both of which adopt SUC hard-sealed cut-off valve 2"-150LB.

[0104] The feed shut-off valve IVb of the receiving tank of slurry process I191 and slurry process II192 both adopt SUC hard-sealed shut-off valve 2"-150LB.

[0105] The flushing cut-off valve IV on the flushing clear liquid pipeline 20 of the slag mixing tank 16 adopts a Suk pneumatic cut-off valve 2"-150LB.

[0106] The 16 level gauge IV of the slag mixing tank adopts Rosemount differential pressure transmitter 2"-150LB, the pressure sensor IV adopts EJA pressure transmitter 2"-150LB, and the temperature sensor IV adopts Zhonghuan integrated temperature transmitter.

[0107] In this embodiment, the synthetic distillation 6-stage tower 6 is a silicon tetrachloride removal tower to remove high-boiling silicon tetrachloride products. The tower kettle regularly extracts heavy components and metal impurities to prevent high-boiling products from accumulating in the tower kettle, causing the tower kettle to be blocked, the reboiler to be worn, and the risk of material leakage. The heavy components and metal impurities extracted from the tower kettle enter the slag stirring tank 16 for stirring to maintain the fluidity and temperature of the high-boiling products and prevent them from solidifying and clogging the pipeline, and finally send them to the slag slurry process for processing and recycling. The tower kettle automatically discharges slag at a fixed time to prevent high-boiling products from accumulating in the tower kettle, causing the tower kettle to be blocked, the reboiler to be worn, and the risk of material leakage. The slag stirring tank 16 is then sent to the slag slurry process for processing and recycling: the material is automatically discharged according to the liquid level of the slag stirring tank 16, and there is no need for on-site inspection and manual operation, which reduces the labor load of employees.

[0108] Example 3 The control system in this embodiment has the same structure as that in Embodiment 1. Compared with Embodiment 1, the control method in this embodiment further includes: The reflux tank 7 also includes an automatic adjustment control of the liquid level of the reflux tank 7 to avoid frequent changes in short-term production affecting downstream processes. At the same time, the liquid level of the reflux tank 7 can also be automatically adjusted. The automatic adjustment control of the liquid level of the reflux tank 7 includes: S701: Setting parameters: setting the interval time, setting the upper limit of the flow setting value of the tower top production regulating valve Ⅱb loop, setting the lower limit of the flow setting value, setting the upper limit, upper limit, lower limit and lower limit of the liquid level of the reflux tank 7; When the liquid level of reflux tank 7 is greater than or equal to the upper limit or less than or equal to the lower limit, the flow rate of the Ⅱb loop of the top extraction regulating valve of the distillation tower is set to the adjustment value SP1; When the liquid level of reflux tank 7 is greater than or equal to the upper limit or less than or equal to the lower limit, the flow rate of the Ⅱb loop of the top extraction regulating valve of the distillation tower is set to the adjustment value SP2; S702: When the liquid level of reflux tank 7 is greater than or equal to the upper limit and the liquid level is less than the upper and lower limits, the flow setting value of the Ⅱb loop of the distillation tower top extraction regulating valve is increased by SP1; after adjustment, the interval time is stabilized, and the program continues to make real-time judgments; When the liquid level of reflux tank 7 is greater than the lower limit and the liquid level is less than or equal to the lower limit L, the flow setting value of the distillation tower top extraction regulating valve Ⅱb loop is reduced by SP1; after adjustment, the stable interval time, the program continues to make real-time judgments; S703: When the liquid level of reflux tank 7 is greater than or equal to the upper limit, the flow setting value of the Ⅱb loop of the distillation tower top extraction regulating valve is increased by SP2; after adjustment, the interval time is stabilized, and the program continues to make real-time judgments; When the liquid level of reflux tank 7 is less than or equal to the lower limit, the set value of the flow rate of the Ⅱb loop of the distillation tower top production regulating valve is reduced by SP2; after adjustment, the stable interval time T1, the program continues to judge in real time. In this embodiment, the liquid level is periodically determined according to the set conditions and the set time, and the set value of the flow rate of the Ⅱb loop of the distillation tower top production regulating valve is automatically adjusted to avoid multiple manual adjustments in a short period of time, thereby ensuring the stability of the production volume.

[0109] Example 4 The difference between this embodiment and embodiment 1 is that, in this embodiment, Figure 2 As shown, the tail gas condensing device includes a tail gas condenser 11 and a condensate tank 21, the inlet of the tail gas condenser 11 is connected to the tail gas discharge pipe 10 of the distillation tower, the outlet of the tail gas condenser 11 is connected to the inlet of the condensate tank 21, the condensate tank 21 is provided with a liquid level gauge III, the outlet of the condensate tank 21 is connected to the raw material tank 13, and the connecting pipeline between the condensate tank and the raw material tank 13 is provided with a condensate pump, a production regulating valve III and a flow meter III; the rest of the structure is the same as that of Example 1.

[0110] The control method in this embodiment also includes: tail gas venting condensate system feeding control, including: S801: When the liquid level of the tail gas condensate tank 21 is higher than 65%, the condensate pump starts automatically, the exhaust regulating valve III mode at the outlet of the tail gas condenser 11 is switched to manual, and the opening of the exhaust regulating valve III is opened to 70%; after 10 seconds, the exhaust regulating valve III mode is switched to automatic, and the exhaust flow rate is set to 13t / h. The regulating valve automatically adjusts the opening according to the deviation between the real-time value of the exhaust flow rate and the set value; S802: When the liquid level of the tail gas condensate tank 21 is lower than 20%, the condensate pump stops running automatically, the exhaust regulating valve III mode at the outlet of the tail gas condenser 11 is switched to manual, and the exhaust regulating valve III is closed; S803: During operation, if the condensate pump current is lower than 8A and lasts for 10 seconds, the condensate pump stops running, the outlet flow regulating valve III of the tail gas condenser 11 is switched to manual mode, and the flow regulating valve III is closed.

[0111] In this embodiment, the liquid level gauge III of the condensate tank 21 adopts EJA differential pressure transmitter 2"-150LB, the production regulating valve III adopts Samson bellows regulating valve DN100 PN40, and the flow meter III adopts E+H mass flow meter.

[0112] In this embodiment, when the liquid level of the tail gas condensate tank 21 is higher than 65% in step S801, the discharge conditions are met and the condensate pump starts automatically; the outlet extraction regulating valve III mode of the tail gas condenser 11 is turned to manual and the opening of the extraction regulating valve III is opened to 70% to avoid large flow fluctuations at the moment of pump startup, and the regulating valve cannot be automatically adjusted, which may cause pump pressure loss or cavitation and damage the equipment; the 10s is continued to ensure that the flow is stable, the pump can start normally, and the regulating valve can be automatically adjusted; in step S802, when the liquid level of the tail gas condensate tank 21 is lower than 20%, the feeding is completed, the condensate pump automatically stops running, the outlet extraction regulating valve III mode of the tail gas condenser 11 is turned to manual, and the extraction regulating valve III is closed to prevent material backflow; During the operation in step S803, if the condensate pump current is lower than 8A and lasts for 10 seconds, it will automatically stop running. This is based on the underload current protection of the pump to avoid damage to the equipment.

[0113] In this embodiment, the tail gas discharged from the synthesis distillation is condensed and reused to improve resource utilization and reduce environmental pollution. The tail gas from the 1st to 6th stage synthesis distillation tower is discharged to the tail gas condenser 11, and the tail gas is condensed and converted from gas to liquid, collected in the condensate tank 21, and finally pumped into the raw material tank 13 area for reuse, so as to realize the recycling of resources.

[0114] Example 5 The difference between this embodiment and embodiment 1 is that, in this embodiment, Figure 3 As shown, the polysilicon distillation process control system also includes a drain liquid tank 22, the inlet of the drain liquid tank 22 is connected to the drain liquid pipeline 25, the outlet of the drain liquid tank 22 is connected to the condensate tank 21, and a vent 23 is provided at the top of the drain liquid tank 22, the vent 23 is connected to the tail gas condenser 11, the drain liquid tank 22 is also connected to a nitrogen pipeline III24, the inlet of the drain liquid tank 22 is provided with a feed cut-off valve III, the nitrogen pipeline III24 is provided with a nitrogen cut-off valve III, the outlet of the drain liquid tank 22 is provided with a discharge cut-off valve III, the vent 23 is provided with a vent cut-off valve III, and the drain liquid tank 22 is provided with a pressure sensor III and a liquid level gauge III; the remaining structure is the same as that of Example 1.

[0115] The control method in this embodiment also includes the control method of the polysilicon distillation process control system and also includes automatic material pressing control of the liquid guiding tank 22, including: S901: When the liquid level of the guide liquid tank 22 is higher than 480 mm, first close the feed cut-off valve III, then close the vent cut-off valve III; open the discharge cut-off valve III to drain the tail gas condensate tank 21, and then open the nitrogen cut-off valve III to pressurize the guide liquid tank 22; S902: When the liquid level of the spraying liquid tank 22 is lower than 80mm, first close the nitrogen cut-off valve III, then close the discharge cut-off valve III; open the air cut-off valve III for 10 seconds, and then open the feed cut-off valve III; S903: In step S901, the timing starts after the nitrogen shut-off valve III of the liquid guiding tank 22 is opened. When the pressure is charged for more than 3 minutes, an alarm is given, and the program automatically opens the vent shut-off valve first for 10 seconds, and then opens the feed shut-off valve; S904: When the number of drainage reaches 2 times within 60 minutes, an alarm will be issued to prompt the main control that the number of drainage times is too many.

[0116] The feed cut-off valve III and the discharge cut-off valve III of the dripping liquid tank 22 both adopt Suk pneumatic cut-off valve 2"-150LB, the nitrogen cut-off valve III and the vent cut-off valve III both adopt Zwick pneumatic cut-off valve 1"-150LB, the pressure sensor III of the dripping liquid tank 22 adopts Rosemount pressure transmitter 2"-150LB, and the liquid level gauge III adopts Mager magnetostrictive liquid level gauge.

[0117] In this embodiment, when the liquid level of the liquid guide tank 22 is higher than 480 mm in step S901, the discharge condition is met; the feed cut-off valve III needs to be closed; the vent valve III is closed because the nitrogen valve needs to be opened for pressurization during the liquid discharge process. If the vent valve is opened during the pressurization, the pressure is insufficient, which affects the liquid discharge; the nitrogen cut-off valve III is opened because pressure is required for liquid discharge, so the nitrogen cut-off valve III needs to be opened for pressurization; the discharge cut-off valve III is opened first, and then the nitrogen cut-off valve III is opened to avoid the pressure in the liquid guide tank 22; In step S902, when the liquid level of the dripping liquid tank 22 is lower than 80 mm, the liquid is not discharged and the feeding condition is met; no pressure is required, so the nitrogen cut-off valve III is closed; secondly, the nitrogen cut-off valve III is closed first, and then the discharge cut-off valve III is closed, which is also to avoid the dripping liquid tank 22 from being pressurized; the venting cut-off valve III is opened first, and then the feed cut-off valve III is opened after 10 seconds, in order to avoid continuous feeding, which may cause overpressure in the dripping liquid tank 22; Step S903 is the interlocking condition during the program operation. The timing starts after the nitrogen shut-off valve III of the dripping liquid tank 22 is opened in S901. When the pressure is charged for more than 3 minutes, an alarm is given (the normal discharge process will not exceed 3 minutes. If the nitrogen shut-off valve III is opened for more than 3 minutes in S902, it indicates that the discharge pipeline is blocked). At the same time, because the discharge pipeline is blocked, the dripping liquid tank 22 will be over-pressurized. At this time, it is necessary to open the venting shut-off valve III to release the pressure. After 10 seconds, the feed shut-off valve III is opened again (repeat the cycle process). Step S904 is an alarm prompt for the drainage process to avoid frequent drainage.

[0118] In this embodiment, the synthetic distillation drainage liquid is collected and reused to improve resource utilization efficiency, reduce waste, and reduce negative impacts on the environment. During the operation of the synthetic distillation device, pumps, filters, samplers and other equipment will discharge a certain amount of drainage liquid regularly or irregularly. These drainage discharge liquids contain materials. If they are discharged directly, they will not only cause waste of resources, but also may pollute the environment. The drainage discharge liquids of each device are collected into the drainage liquid tank 22, and then fed to the condensate tank 21, and finally pumped into the raw material tank 13 area for reuse to achieve resource recycling.

[0119] Application Examples The present application example provides a polysilicon distillation process control system, including a 6-stage distillation tower, wherein the top outlet of the distillation tower is connected to a reflux tank 7, the distillation tower kettle is provided with a heat exchanger 8, the bottom of the reflux tank 7 is connected to a reflux pump 9, the reflux outlet of the reflux pump 9 is connected to the top of the distillation tower at this stage, the top of the distillation tower is provided with a tail gas discharge pipe 10, the tail gas discharge pipe 10 is connected to a tail gas condensing device, the outlet of the reflux pump 9 of the first-stage tower 1 is connected to the feed inlet of the second-stage tower 2, the outlet of the reflux pump 9 of the second-stage tower 2 is connected to the anti-disproportionation device 12, the outlet of the reflux pump 9 of the third-stage tower 3 is connected to the feed inlet of the fourth-stage tower 4, the outlet of the reflux pump 9 of the fourth-stage tower 4 is connected to a raw material tank 13, the outlet of the reflux pump 9 of the fifth-stage tower 5 is connected to a trichlorosilane refining tank 14, the outlet of the reflux pump 9 of the sixth-stage tower 6 is connected to a trichlorosilane refining tank 15, and the outlet of the reflux pump 9 of the sixth-stage tower 6 is connected to a trichlorosilane refining tank 16. The extraction outlet of the reflux pump 9 is connected to the silicon tetrachloride storage tank 15; the feed port of the first-stage tower 1 is connected to the raw material tank 13, and the tower bottom discharge port of the first-stage tower 1 is connected to the feed port of the sixth-stage tower 6; the tower bottom discharge port of the second-stage tower 2 is connected to the feed port of the third-stage tower 3, and the tower bottom discharge port of the third-stage tower 3 is connected to the raw material tank 13; the tower bottom discharge port of the fourth-stage tower 4 is connected to the feed port of the fifth-stage tower 5, and the tower bottom discharge port of the fifth-stage tower 5 is connected to the raw material tank 13, and the tower bottom discharge port of the sixth-stage tower 6 is connected to the slag stirring tank 16; the outlet of the tail gas discharge pipe 10 of the distillation tower is provided with a venting regulating valve II, the top of the distillation tower is provided with a pressure sensor II, the reflux tank 7 is provided with a liquid level meter IIa, the tower bottom of the distillation tower is provided with a liquid level meter IIb, and the tower bottom discharge port of the distillation tower is provided with a flow meter IIb and a tower bottom extraction regulating valve II. Valve Ⅱa; the reflux outlet of the reflux pump 9 is provided with a reflux regulating valve Ⅱ and a flowmeter Ⅱc; the production outlet of the reflux pump 9 is provided with a tower top production regulating valve Ⅱb and a flowmeter Ⅱd; the top of the distillation tower is provided with a temperature sensor Ⅱa, the bottom of the tower is provided with a temperature sensor Ⅱb, and the tower is provided with a temperature sensor Ⅱc; the heating medium pipeline of the heat exchanger 8 of the 1st tower 1, the 3rd tower 3 and the 6th tower 6 is connected to the steam main pipeline 17; the tower top production outlet of the 3rd tower 3, the 5th tower 5 and the 6th tower 6 is respectively connected to the heating medium pipeline inlet of the upper distillation tower heat exchanger 8, and the inlet of the reflux tank 7 of the 3rd tower 3, the 5th tower 5 and the 6th tower 6 is respectively connected to the outlet of the heating medium pipeline of the upper distillation tower heat exchanger 8; the heating medium inlet of the heat exchanger 8 of the distillation tower They are all provided with a heating medium regulating valve and a temperature sensor IId, and the steam main pipeline 17 is provided with a pressure sensor I; the heating medium pipeline inlet of the heat exchanger 8 of the 1st tower 1, the 3rd tower 3 and the 6th tower 6 is provided with a flow meter IIa; the feed inlet of the 1st tower 1 is provided with a feed regulating valve I and a flow meter Ib, and the raw material tank 13 is provided with a liquid level gauge I; the slag stirring tank 16 is connected to a nitrogen pipeline IV18, and a nitrogen cut-off valve IV is respectively provided on the nitrogen pipeline IV18; the slag stirring tank 16 is respectively provided with a venting pipeline IV26, and a venting cut-off valve IV is respectively provided on the venting pipeline IV26; the connecting pipeline between the slag stirring tank 16 and the 6th tower 6 kettle is respectively provided with a feed cut-off valve IVa; the discharge port of the slag stirring tank 16 is connected to the slag slurry process;The connecting pipeline between the discharge port of the slag stirring tank 16 and the slurry process is provided with a feed shut-off valve IV; the slag stirring tank 16 is provided with two, the inlet of the slag stirring tank 16 is respectively connected to the 6th tower kettle of the 6th stage tower, and the outlet of the slag stirring tank 16 is respectively connected to the slurry process; the slurry process is provided with a slurry process I191 and a slurry process II192, and the slurry process I191 and the slurry process II192 are respectively connected to the two slag stirring tanks 16; the slurry process I191 and the slurry process II192 are respectively provided with two receiving tanks, and the feed ports of the receiving tanks are respectively provided with feed shut-off valves IVb; the discharge ports of the slag stirring tank 16 are respectively connected to the flushing clear liquid pipeline 20, and the flushing clear liquid pipeline 20 is respectively provided with a flushing shut-off valve IV; the slag stirring tank 16 is provided with a liquid level gauge IV, a pressure sensor IV and a temperature sensor IV; the tail gas condensing device comprises a tail gas condenser 11 and a condensate tank 21, and the inlet of the tail gas condenser 11 The outlet of the tail gas condenser 11 is connected to the inlet of the condensate tank 21, the condensate tank 21 is provided with a liquid level gauge III, the outlet of the condensate tank 21 is connected to the raw material tank 13, and the connecting pipeline between the condensate tank and the raw material tank 13 is provided with a condensate pump, a production regulating valve III and a flow meter III; the polysilicon distillation process control system also includes a dripping liquid tank 22, the inlet of the dripping liquid tank 22 is connected to the dripping liquid pipeline 25, and the dripping liquid tank 22 The outlet of the condensate tank 21 is connected, the top of the leaching liquid tank 22 is provided with a vent 23, the vent 23 is connected to the tail gas condenser 11, the leaching liquid tank 22 is also connected to the nitrogen pipeline III 24, the inlet of the leaching liquid tank 22 is provided with a feed cut-off valve III, the nitrogen pipeline III 24 is provided with a nitrogen cut-off valve III, the outlet of the leaching liquid tank 22 is provided with a discharge cut-off valve III, the vent 23 is provided with a vent cut-off valve III, and the leaching liquid tank 22 is provided with a pressure sensor III and a liquid level gauge III. ;

[0120] This application example also provides a control method for the above control system, including: distillation tower top vent flow control, reflux flow control, tower top extraction flow control, tower bottom extraction flow control and tower bottom temperature control; The vent flow control of the distillation tower top comprises: setting the tower top control pressure, monitoring the tower top pressure value in real time through the pressure sensor II, when there is a positive deviation between the tower top real-time pressure value and the set pressure value, the vent regulating valve II increases the output opening to automatically adjust the pressure value; when there is a negative deviation between the tower top real-time pressure value and the set pressure value, the vent regulating valve II reduces the output opening to automatically adjust the pressure value; The reflux flow control includes: the reflux regulating valve II of the first-stage tower 1 is automatically controlled with the reflux flow in a single loop; the reflux regulating valve II of the second-stage tower 2 is controlled with the reflux flow and the tower top temperature in cascade; the reflux regulating valve II of the third-stage tower 3, the fifth-stage tower 5 and the sixth-stage tower 6 is controlled with the tower kettle liquid level and the reflux flow in cascade; the reflux regulating valve II of the fourth-stage tower 4 is controlled with the reflux tank 7 liquid level and the reflux flow in cascade; The tower top production flow control includes cascade control of the tower top production regulating valve IIb of the first-stage tower 1, the third-stage tower 3 and the sixth-stage tower 6, the liquid level of the reflux tank 7 and the tower top production flow; single-loop automatic control of the tower top production regulating valve IIb and the liquid level of the reflux tank 7 of the second-stage tower 2; single-loop automatic control of the tower top production regulating valve IIb and the tower top production flow of the fourth-stage tower 4 and the fifth-stage tower 5; The tower kettle extraction flow control includes cascade control of the tower kettle extraction regulating valve IIa, the tower kettle liquid level, and the tower kettle extraction flow of the first-stage tower 1, the second-stage tower 2, and the fourth-stage tower 4; and single-loop automatic control of the tower kettle extraction regulating valve IIa and the tower kettle extraction flow of the third-stage tower 3 and the fifth-stage tower 5; The tower kettle temperature control includes: single-loop automatic control of the heating medium regulating valve and the tower kettle temperature of the 1st-stage tower 1 and the 3rd-stage tower 3; cascade control of the heating medium regulating valve, steam flow IIa, and the tower kettle temperature of the 6th-stage tower 6; The first-stage tower 1, the third-stage tower 3 and the sixth-stage tower 6 also include steam automatic adjustment control, including the following steps: S101: Setting parameters: setting sampling time, triggering time, steam main set pressure difference PI-SP and heating medium regulating valve opening adjustment set value OUT-SP; S102: monitor the pressure in the steam main in real time through the pressure sensor 1, and calculate the average value of the previous 6 sampling pressures; S103: Calculate the difference between the current pressure of the steam main and the average pressure of the steam main, and set judgment condition 1 and judgment condition 2; The judgment condition 1 is: the difference between the current pressure of the steam main and the average pressure of the steam main is greater than or equal to the set pressure difference PI-SP of the steam main; The judgment condition 2 is: when the difference between the current pressure of the steam main and the average pressure of the steam main is less than the set pressure difference PI-SP of the steam main; S104: When neither condition 1 nor condition 2 is satisfied, continue to make real-time judgment; When condition 1 is met within T2 consecutive times, the heating medium regulating valve loop mode is switched to manual, and the valve opening is reduced to OUT-SP; after stabilization for 2S, the heating medium regulating valve loop mode is switched to automatic, and the last automatic mode flow setting value is restored; When condition 2 is met within a continuous period of T2, the heating medium regulating valve circuit mode is switched to manual, and the valve opening is widened to OUT-SP; after stabilization for 2S, the heating medium regulating valve circuit mode is switched to automatic, and the flow setting value of the last automatic mode is restored; The first-stage tower 1 also includes an automatic feed control, including the following steps: S201: Set parameters: Set the adjustment interval time of the feed set value of the PID loop of the feed regulating valve I; in the automatic mode of the PID loop of the feed regulating valve I, set the upper limit and lower limit of the feed flow set value; set the high-high limit, high limit, low limit and low-low limit of the liquid level of the raw material tank 13. S202: The feed regulating valve I and the single-loop automatic control of the feed flow, the action form of the PID loop is reverse action; the feed flow of the distillation column is monitored in real time through the flowmeter Ib. When there is a positive deviation between the real-time feed flow value and the set flow value, the feed regulating valve I reduces the output opening to automatically adjust the feed flow value; when there is a negative deviation between the real-time feed flow value and the set flow value, the feed regulating valve I increases the output opening to automatically adjust the feed flow value; when it is necessary to reduce the output opening of the feed regulating valve I and the feed flow set value reaches the lower limit, no adjustment is made; when it is necessary to increase the output opening of the feed regulating valve I and the feed flow set value reaches the upper limit, no adjustment is made. S203: When the liquid level of the raw material tank 13 ≥ the high limit and the liquid level < the high-high limit, the feed flow set value of the PID loop of the feed regulating valve I increases by SP1; after adjustment, after the adjustment interval time, the program continues to judge in real time. S204: When the liquid level of the raw material tank 13 > the low-low limit and the liquid level ≤ the low limit, the feed flow set value of the PID loop of the feed regulating valve I decreases by SP1; after adjustment, after the adjustment interval time, the program continues to judge in real time. S205: When the liquid level of the raw material tank 13 ≥ the high-high limit, the feed flow set value of the PID loop of the feed regulating valve I increases by SP2; after adjustment, after the adjustment interval time, the program continues to judge in real time. S206: When the liquid level of the raw material tank 13 ≤ the low-low limit, the feed flow set value of the PID loop of the feed regulating valve I decreases by SP2; after adjustment, after the adjustment interval time, the program continues to judge in real time. The first-stage tower 1 further includes the automatic control of the middle temperature of the tower, including the following steps: S301: Set parameters: Set the adjustment interval time of the temperature set value of the PID loop of the heating medium regulating valve; in the automatic mode of the PID loop of the heating medium regulating valve, set the upper limit and lower limit of the temperature set value; set the high-high limit, high limit, low-low limit and low limit of the middle temperature of the first-stage tower 1. S302: When the middle temperature of the first-stage tower 1 ≥ the high limit and the middle temperature < the high-high limit, the temperature set value of the PID loop of the heating medium regulating valve increases by SP1; after adjustment, after the adjustment interval time, the program continues to judge in real time. S303: When the middle temperature of the first-stage tower 1 > the low-low limit and the middle temperature ≤ the low limit, the temperature set value of the PID loop of the heating medium regulating valve decreases by SP1; after adjustment, after the adjustment interval time, the program continues to judge in real time. S304: When the medium temperature of the first stage tower 1 is ≥ the upper limit, the temperature setting value of the heating medium regulating valve PID loop is increased by SP2; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments; S305: When the temperature in the first stage tower 1 is less than or equal to the lower limit, the temperature setting value of the heating medium regulating valve PID loop is reduced by SP2; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments; The distillation tower also includes an automatic reflux ratio adjustment control, which automatically adjusts the reflux ratio according to the extraction flow rate at the top of the distillation tower to ensure the stability of the reflux of the distillation tower, ensure the distillation effect, and reduce energy consumption; including: S401: Input reflux ratio setting value; S402: The flow setting value of the reflux regulating valve II of the distillation tower is automatically adjusted to the product of the reflux ratio setting value and the tower top extraction flow rate; S403: The PID control loop of the reflux regulating valve II is in the reverse action mode; the real-time value of the tower top reflux flow is monitored in real time by the flow meter IIc; when there is a positive deviation between the real-time value of the reflux flow and the set value of the reflux flow, the reflux regulating valve II reduces the output opening to automatically adjust the reflux flow; when there is a negative deviation between the real-time value of the reflux flow and the set value of the reflux flow, the reflux regulating valve II increases the output opening to automatically adjust the reflux flow; so that the reflux flow value of the distillation tower is basically stable and maintained at the set value; The six-stage tower 6 also includes automatic slag discharge control for the tower bottom, including the following steps: S501: setting the material receiving amount of the two slag mixing tanks 16 respectively; S502: judging the slag discharge conditions of the synthetic distillation 6-stage tower 6, including: when the liquid level of one of the slag mixing tanks 16 is less than 54%, the pressure is less than 0.2 MPa, and the venting shut-off valve IV is in an open state, the slag mixing tank 16 is discharged and fed; when both slag mixing tanks 16 meet the above conditions, the slag mixing tank 16 with a higher liquid level is discharged and fed; when both slag mixing tanks 16 do not meet the above conditions, waiting for the slag mixing tank 16 to meet the material receiving conditions; S503: When one of the slag mixing tanks 16 meets the slag discharge condition described in S502, the nitrogen shut-off valve IV of the slag mixing tank 16 that meets the slag discharge condition is closed, the vent shut-off valve IV of the slag mixing tank 16 that meets the slag discharge condition is opened, the feed shut-off valve IVa of the slag mixing tank 16 that does not meet the slag discharge condition is closed, and the timing RET1 is started; After the above-mentioned cut-off valve is fed back to the right position, the feed cut-off valve IVa of the slag mixing tank 16 that meets the slag discharge conditions is opened, and the timing RET2 is started; When the liquid level of the slag mixing tank 16 that meets the slag discharge conditions rises by more than the set material receiving amount, the feed cut-off valve IVa of the mixing tank is closed; When RET2 counts to 30 minutes, and the feed cut-off valve of the slag mixing tank 16 that meets the slag discharge conditions is not closed and is still feeding, it will prompt: Synthesis distillation 6-stage tower 6 slag discharge timeout, please confirm; S504: When the RET1 timing reaches 160 minutes, repeat steps S502-S503. When both slag mixing tanks 16 do not meet the material collection conditions, the circulation conditions are not met, and it is prompted that the slag discharge conditions of the 6-stage tower 6 are not met. The slag mixing tank 16 includes automatic discharge control, including the following steps: S601: setting the discharge amount of the two slag mixing tanks 16 respectively; S602: Determine the discharge conditions of the slag mixing tank 16: When the liquid level of one of the slag mixing tanks 16 is greater than 65% and the liquid level of the other slag mixing tank 16 is less than or equal to 65%, the slag mixing tank 16 with a liquid level greater than 65% discharges the material; When the liquid levels of the two slag mixing tanks 16 are both greater than 65%, the slag mixing tank 16 with a higher liquid level will discharge the material; When the liquid levels of the two slag mixing tanks 16 are both ≤65%, the slag mixing tank 16 with a liquid level of >54% will discharge the material; When the liquid levels of the two slag mixing tanks 16 are both ≤65%, and when the liquid levels of the two slag mixing tanks 16 are both >54%, the slag mixing tank 16 with the higher liquid level will discharge the material; When the liquid levels of the two slag mixing tanks 16 are both ≤65%, and when the liquid levels of the two slag mixing tanks 16 are both ≤54%, the liquid level conditions are re-judged; S603: Determine the slag material mixing tank 16 for discharging according to the discharging conditions in step S602, and close the venting cut-off valve IV and the feed cut-off valve IVa of the discharging slag material mixing tank 16; S604: monitor the pressure in the slag mixing tank 16 of the discharge material in real time through the pressure sensor IV. When the pressure is ≥0.6MPa, execute the next step; when the pressure is <0.6MPa, open the nitrogen cut-off valve IV of the slag mixing tank 16 of the discharge material, charge the pressure to 0.6MPa, close the nitrogen cut-off valve IV, and execute the next step; S605: Determine the discharge path: by default, start from the slurry process I191 to confirm the discharge conditions each time; Material collection conditions of slurry process I: the feed cut-off valve IVb of the two material collection tanks of the feed process I meets an open state, the discharge cut-off valve IV between the discharge slag mixing tank 16 and the slurry process II 192 is closed, and the discharge cut-off valve IV between the discharge slag mixing tank 16 and the slurry process I 191 is opened; Material receiving conditions of slurry process II: the feed cut-off valve IVb of the two material receiving tanks of the feed process II meets an open state, the discharge cut-off valve IV between the discharge slag mixing tank 16 and the slurry process I191 is closed, and the discharge cut-off valve IV between the discharge slag mixing tank 16 and the slurry process II192 is opened; S606: Start discharging. When the discharging amount of the slag material mixing tank 16 is greater than the set value or the liquid level in the slag material mixing tank 16 is less than 15%, close the discharging cut-off valve IV and the nitrogen cut-off valve IV of the slag material mixing tank 16; S607: After closing the discharge cut-off valve IV and the nitrogen cut-off valve IV, open the clear liquid cut-off valve of the discharge slag mixing tank 16 for flushing, and start timing; when the 300s timing is up, close the clear liquid cut-off valve IV of the discharge slag mixing tank 16, and open the venting cut-off valve IV; S608: During the discharging process, the pressure of the slag mixing tank 16 is maintained between 0.55 and 0.6 MPa; during the discharging process, if the feed cut-off valves IVb of the two receiving tanks of the slurry process I191 or the slurry process II192 are both closed, an alarm is triggered, and after confirmation by the main control, the confirmation and judgment of the discharging path are restarted; during the discharging process, if the feed cut-off valves IVb of the two receiving tanks of any slurry process are both closed, an alarm is triggered; The reflux tank 7 also includes a reflux tank 7 liquid level automatic adjustment control, including the following steps: S701: Setting parameters: setting the interval time, setting the upper limit of the flow setting value of the tower top production regulating valve Ⅱb loop, setting the lower limit of the flow setting value, setting the upper limit, upper limit, lower limit and lower limit of the liquid level of the reflux tank 7; When the liquid level of reflux tank 7 is greater than or equal to the upper limit or less than or equal to the lower limit, the flow rate of the Ⅱb loop of the top extraction regulating valve of the distillation tower is set to the adjustment value SP1; When the liquid level of reflux tank 7 is greater than or equal to the upper limit or less than or equal to the lower limit, the flow rate of the Ⅱb loop of the top extraction regulating valve of the distillation tower is set to the adjustment value SP2; S702: When the liquid level of reflux tank 7 is greater than or equal to the upper limit and the liquid level is less than the upper and lower limits, the flow setting value of the Ⅱb loop of the distillation tower top extraction regulating valve is increased by SP1; after adjustment, the interval time is stabilized, and the program continues to make real-time judgments; When the liquid level of reflux tank 7 is greater than the lower limit and the liquid level is less than or equal to the lower limit L, the flow setting value of the distillation tower top extraction regulating valve Ⅱb loop is reduced by SP1; after adjustment, the stable interval time, the program continues to make real-time judgments; S703: When the liquid level of reflux tank 7 is greater than or equal to the upper limit, the flow setting value of the Ⅱb loop of the distillation tower top extraction regulating valve is increased by SP2; after adjustment, the interval time is stabilized, and the program continues to make real-time judgments; When the liquid level of reflux tank 7 is less than or equal to the lower limit, the set value of the flow rate of the Ⅱb loop of the distillation tower top extraction regulating valve is reduced by SP2; after adjustment, the stable interval time is T1, and the program continues to make real-time judgments; The tail gas condensation device includes a tail gas venting condensate system feeding control, including: S801: When the liquid level of tail gas condensate tank 21 is higher than 65%, the condensate pump starts automatically, and the opening of the production regulating valve III is opened to 70%; after 10 seconds, the production regulating valve III mode is switched to automatic, and the production flow is set. The production regulating valve III automatically adjusts the opening according to the deviation between the real-time value of the production flow and the set value; S802: When the liquid level of the tail gas condensate tank 21 is lower than 20%, the condensate pump automatically stops running and closes the extraction regulating valve III; S803: During operation, if the condensate pump current is lower than 8A and lasts for 10 seconds, the condensate pump stops running and the production regulating valve III is closed; The control method of the polysilicon distillation process control system also includes automatic material pressing control of the liquid guiding tank 22, including: S901: When the liquid level of the guide liquid tank 22 is higher than the set value, first close the feed cut-off valve III, then close the vent cut-off valve III; open the discharge cut-off valve III to drain the tail gas condensate tank 21, and then open the nitrogen cut-off valve III to pressurize the guide liquid tank 22; S902: When the liquid level of the spraying liquid tank 22 is lower than the set value, first close the nitrogen cut-off valve III, then close the discharge cut-off valve III; open the air cut-off valve III for 10 seconds, and then open the feed cut-off valve III; S903: in step S901, the timing starts after the nitrogen shut-off valve III of the liquid guide tank is opened. When the pressure is charged for more than 3 minutes, an alarm is given, and the program automatically opens the vent shut-off valve first for 10 seconds, and then opens the feed shut-off valve. S904: When the number of drainage reaches 2 times within 60 minutes, an alarm will be issued to prompt the main control that the number of drainage times is too many.

[0121] Comparative Example The difference between this comparative example and the application example is that in this application example, in 2023, where the automatic control system is not used in this comparative example, manual control and adjustment of each point are adopted.

[0122] The raw material high-impurity chlorosilane material was separated and purified by using the above application examples and comparative examples, and finally a refined trichlorosilane material was obtained. The P content results of the refined trichlorosilane material are shown in Table 1, the B content results are shown in Table 2, the metal impurity content is shown in Table 3, the resistivity of the high-purity crystalline silicon product is shown in Table 4, and the trichlorosilane concentration is shown in Table 5.

[0123] Table 1 P content of refined trichlorosilane materials in application examples and comparative examples Table 2 B content of refined trichlorosilane materials in application examples and comparative examples Table 3 Metal impurity content of refined trichlorosilane materials in application examples and comparative examples Table 4 Trichlorosilane concentration of refined trichlorosilane materials in application examples and comparative examples Table 5 Resistivity of high purity silicon products in application examples and comparative examples Workload of employees (four shifts, three shifts, 8 hours per shift) 1. Main control Comparison ratio: 2023: Average number of operations per shift 700+; Application example: Early February 2024: average number of operations per shift 30+, early July 2024: average number of operations per shift 9+; 2. Inspection Comparison ratio: 2023: 20 people, average operation time per shift: 4 hours / person; Application example: 2024: 16 people, average operation time per person per shift: 3 hours; As can be seen from Tables 1-5, the P content of the refined trichlorosilane material obtained in the application example in 2024 was reduced by 19% compared with that in the comparison example in 2023, the B content was reduced by 54%, the metal impurity content was reduced by 26%, the trichlorosilane concentration was increased by 0.25%, and the resistivity of the high-purity silicon product in 2024 was increased by 77.8% compared with that in 2023. The quality of the products produced in the application example was greatly improved compared with the comparison example, which directly shows that the implementation of the application example can greatly improve the company's products, so that the company's production of high-purity silicon products can maintain quality competitiveness among many silicon material companies.

[0124] The improvement in quality is mainly due to the implementation of automatic control. Through the logic control program, the parameters are adjusted accurately to avoid the impact of operational differences among different operators, so as to achieve stable parameters of the distillation tower throughout the entire process and improve product quality.

[0125] In terms of material balance, the liquid level of the raw material tank is periodically determined according to the set conditions and set time, and the flow setting value of the distillation tower feed regulating valve loop is automatically adjusted to maintain the stability of the feed amount, prevent over-adjustment, and avoid quality deviation. According to the set conditions and set time, the liquid level is periodically determined, and the flow setting value of the distillation tower top extraction regulating valve loop is automatically adjusted. While controlling the liquid level balance of the reflux tank, multiple adjustments in a short period of time are avoided to ensure the stability of the extraction amount. In terms of heat balance, the opening of the heating medium regulating valve is adjusted in advance according to the pressure changes of the steam main pipe to avoid temperature fluctuations in the distillation tower kettle. At the same time, according to the changes in the temperature in the distillation tower, the temperature setting value of the distillation tower heating medium regulating valve loop is automatically adjusted, changing from a single temperature variable control to a dual variable control of the tower kettle temperature and the tower temperature, which can better match the changes in the feed amount and stabilize the distillation tower temperature. In terms of reflux ratio control, the reflux ratio is automatically adjusted according to the extraction flow rate at the top of the distillation tower to ensure the stability of the reflux ratio of the distillation tower, ensure the distillation effect, and reduce energy consumption.

[0126] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A polysilicon distillation process control system, characterized in that: The invention comprises a 6-stage distillation tower, wherein the top outlet of the distillation tower is connected to a reflux tank (7), the bottom of the distillation tower is provided with a heat exchanger (8), the bottom of the reflux tank (7) is connected to a reflux pump (9), the reflux outlet of the reflux pump (9) is connected to the top of the distillation tower of the current stage, the top of the distillation tower is provided with a tail gas discharge pipe (10), the tail gas discharge pipe (10) is connected to a tail gas condensing device, the outlet of the reflux pump (9) of the first stage tower (1) is connected to the feed inlet of the second stage tower (2), the outlet of the reflux pump (9) of the second stage tower (2) is connected to the anti-disproportionation device (12), the outlet of the reflux pump (9) of the third stage tower (3) is connected to the feed inlet of the fourth stage tower (4), the outlet of the reflux pump (9) of the fourth stage tower (4) is connected to the raw material outlet The extraction outlet of the reflux pump (9) of the 5-stage tower (5) is connected to the trichlorosilane refining tank (14), and the extraction outlet of the reflux pump (9) of the 6-stage tower (6) is connected to the silicon tetrachloride storage tank (15); the feed port of the 1-stage tower (1) is connected to the raw material tank (13), and the tower bottom discharge port of the 1-stage tower (1) is connected to the feed port of the 6-stage tower (6); the tower bottom discharge port of the 2-stage tower (2) is connected to the feed port of the 3-stage tower (3), and the tower bottom discharge port of the 3-stage tower (3) is connected to the raw material tank (13); the tower bottom discharge port of the 4-stage tower (4) is connected to the feed port of the 5-stage tower (5), and the tower bottom discharge port of the 5-stage tower (5) is connected to the raw material tank (13), and the tower bottom discharge port of the 6-stage tower (6) is connected to the slag mixing tank (16); The outlet of the tail gas discharge pipe (10) of the distillation tower is provided with a venting regulating valve II, the top of the distillation tower is provided with a pressure sensor II, the reflux tank (7) is provided with a liquid level gauge IIa, the bottom of the distillation tower is provided with a liquid level gauge IIb, and the discharge port of the bottom of the distillation tower is provided with a flow meter IIb and a bottom extraction regulating valve IIa; The reflux outlet of the reflux pump (9) is provided with a reflux regulating valve II and a flow meter IIc; the production outlet of the reflux pump (9) is provided with a tower top production regulating valve IIb and a flow meter IId; The distillation tower is provided with a temperature sensor IIa at the top, a temperature sensor IIb at the bottom, and a temperature sensor IIc in the middle.

2. A polysilicon distillation process control system according to claim 1, characterized in that: The heating medium pipelines of the heat exchangers (8) of the first-stage tower (1), the third-stage tower (3) and the sixth-stage tower (6) are connected to the steam main pipeline (17); the top outlets of the third-stage tower (3), the fifth-stage tower (5) and the sixth-stage tower (6) are respectively connected to the inlet of the heating medium pipeline of the heat exchanger (8) of the upper-stage distillation tower, and the inlet of the reflux tank (7) of the third-stage tower (3), the fifth-stage tower (5) and the sixth-stage tower (6) are respectively connected to the outlet of the heating medium pipeline of the heat exchanger (8) of the upper-stage distillation tower; the heating medium inlet of the heat exchanger (8) of the distillation tower is provided with a heating medium regulating valve and a temperature sensor IId, and the steam main pipeline (17) is provided with a pressure sensor I; the heating medium pipeline inlet of the heat exchanger (8) of the first-stage tower (1), the third-stage tower (3) and the sixth-stage tower (6) is provided with a flow meter IIa.

3. The polysilicon distillation process control system according to claim 1, characterized in that: The feed inlet of the first-stage tower (1) is provided with a feed regulating valve I and a flow meter Ib, and the raw material tank (13) is provided with a liquid level meter I.

4. The polysilicon distillation process control system according to claim 1, characterized in that: The slag stirring tank (16) is connected to a nitrogen pipeline IV (18), and a nitrogen shut-off valve IV is provided on the nitrogen pipeline IV (18); the slag stirring tank (16) is provided with a venting pipeline IV (26), and a venting shut-off valve IV is provided on the venting pipeline IV (26); a feed shut-off valve IVa is provided on the connecting pipeline between the slag stirring tank (16) and the kettle of the 6-stage tower (6); the discharge port of the slag stirring tank (16) is connected to the slag slurry process; and a feed shut-off valve IV is provided on the connecting pipeline between the discharge port of the slag stirring tank (16) and the slag slurry process.

5. A polysilicon distillation process control system according to claim 4, characterized in that: Two slag material stirring tanks (16) are provided, the inlets of the slag material stirring tanks (16) are respectively connected to the kettle of the 6-stage tower (6), and the outlets of the slag material stirring tanks (16) are respectively connected to the slag slurry process.

6. A polysilicon distillation process control system according to claim 5, characterized in that: The slurry process setting includes a slurry process I (191) and a slurry process II (192), and the slurry process I (191) and the slurry process II (192) are respectively connected to two slag material mixing tanks (16).

7. A polysilicon distillation process control system according to claim 6, characterized in that: The slag slurry process I (191) and the slag slurry process II (192) are each provided with two material receiving tanks, and the material inlets of the material receiving tanks are each provided with a material feed shut-off valve IVb; the material outlets of the slag material mixing tank (16) are respectively connected to flushing clear liquid pipelines (20), and the flushing clear liquid pipelines (20) are respectively provided with flushing shut-off valves IV; the slag material mixing tank (16) is provided with a liquid level gauge IV, a pressure sensor IV and a temperature sensor IV.

8. The polysilicon distillation process control system according to claim 1, characterized in that: The tail gas condensing device comprises a tail gas condenser (11) and a condensate tank (21), wherein the inlet of the tail gas condenser (11) is connected to the tail gas discharge pipe (10) of the distillation tower, the outlet of the tail gas condenser (11) is connected to the inlet of the condensate tank (21), the condensate tank (21) is provided with a liquid level gauge III, the outlet of the condensate tank (21) is connected to the raw material tank (13), and the connecting pipeline between the condensate tank and the raw material tank (13) is provided with a condensate pump, a production regulating valve III and a flow meter III.

9. The polysilicon distillation process control system according to claim 1, characterized in that: The polysilicon distillation process control system further comprises a liquid guiding tank (22), the inlet of the liquid guiding tank (22) being connected to a liquid guiding pipeline (25), the outlet of the liquid guiding tank (22) being connected to a condensate tank (21), a venting port (23) being provided at the top of the liquid guiding tank (22), the venting port (23) being connected to a tail gas condenser (11), the liquid guiding tank (22) being further connected to a nitrogen pipeline III (24), the inlet of the liquid guiding tank (22) being provided with a feed shut-off valve III, the nitrogen pipeline III (24) being provided with a nitrogen shut-off valve III, the outlet of the liquid guiding tank (22) being provided with a discharge shut-off valve III, the venting port (23) being provided with a venting shut-off valve III, and the liquid guiding tank (22) being provided with a pressure sensor III and a liquid level gauge III.

10. A control method for a polysilicon distillation process control system, characterized in that: The method is applied to the control method of the polysilicon distillation process control system as described in any one of claims 1 to 9, including: distillation tower top venting pressure control, reflux flow control, tower top production flow control, tower bottom production flow control and tower bottom temperature control.

11. The control method of a polysilicon distillation process control system according to claim 10, characterized in that: The venting pressure control of the distillation tower top includes: setting the tower top control pressure, monitoring the tower top pressure value in real time through the pressure sensor II, when there is a positive deviation between the tower top real-time pressure value and the set pressure value, the venting regulating valve II increases the output opening to automatically adjust the pressure value; when there is a negative deviation between the tower top real-time pressure value and the set pressure value, the venting regulating valve II reduces the output opening to automatically adjust the pressure value.

12. The control method of a polysilicon distillation process control system according to claim 10, characterized in that: The reflux flow control includes: the reflux regulating valve II of the first-stage tower (1) and the single-loop automatic control of the reflux flow; the reflux regulating valve II of the second-stage tower (2) and the reflux flow and the tower top temperature are controlled in series; the reflux regulating valve II of the third-stage tower (3), the fifth-stage tower (5) and the sixth-stage tower (6) and the tower bottom liquid level and the reflux flow are controlled in series; the reflux regulating valve II of the fourth-stage tower (4) and the reflux tank (7) liquid level and the reflux flow are controlled in series.

13. The control method of a polysilicon distillation process control system according to claim 10, characterized in that: The tower top extraction flow control includes cascade control of the tower top extraction regulating valve IIb, the liquid level of the reflux tank (7), and the tower top extraction flow of the first-stage tower (1), the third-stage tower (3), and the sixth-stage tower (6); single-loop automatic control of the tower top extraction regulating valve IIb and the liquid level of the reflux tank (7) of the second-stage tower (2); and single-loop automatic control of the tower top extraction regulating valve IIb and the tower top extraction flow of the fourth-stage tower (4) and the fifth-stage tower (5).

14. The control method of a polysilicon distillation process control system according to claim 10, characterized in that: The tower bottom extraction flow control comprises cascade control of the tower bottom extraction regulating valve IIa, the tower bottom liquid level and the tower bottom extraction flow of the first-stage tower (1), the second-stage tower (2) and the fourth-stage tower (4); and single-loop automatic control of the tower bottom extraction regulating valve IIa and the tower bottom extraction flow of the third-stage tower (3) and the fifth-stage tower (5).

15. The control method of a polysilicon distillation process control system according to claim 10, characterized in that: The tower bottom temperature control comprises: single-loop automatic control of the heating medium regulating valve and the tower bottom temperature of the 1st-stage tower (1) and the 3rd-stage tower (3); and cascade control of the heating medium regulating valve, steam flow IIa and the tower bottom temperature of the 6th-stage tower (6).

16. The control method of a polysilicon distillation process control system according to claim 10, characterized in that: The first-stage tower (1), the third-stage tower (3) and the sixth-stage tower (6) further include a steam automatic adjustment control, comprising the following steps: S101: Setting parameters: setting sampling time, triggering time, steam main set pressure difference PI-SP and heating medium regulating valve opening adjustment set value OUT-SP; S102: monitor the pressure in the steam main in real time through the pressure sensor 1, and calculate the average value of the previous 6 sampling pressures; S103: Calculate the difference between the current pressure of the steam main and the average pressure of the steam main, and set judgment condition 1 and judgment condition 2; The judgment condition 1 is: the difference between the current pressure of the steam main and the average pressure of the steam main is greater than or equal to the set pressure difference PI-SP of the steam main; The judgment condition 2 is: when the difference between the current pressure of the steam main and the average pressure of the steam main is less than the set pressure difference PI-SP of the steam main; S104: When neither condition 1 nor condition 2 is satisfied, continue to make real-time judgment; When condition 1 is met within T2 consecutive times, the heating medium regulating valve loop mode is switched to manual, and the valve opening is reduced to OUT-SP; after stabilization for 2S, the heating medium regulating valve loop mode is switched to automatic, and the last automatic mode flow setting value is restored; When condition 2 is met within the continuous T2 time, the heating medium regulating valve circuit mode is switched to manual, and the valve opening is widened OUT-SP; after stabilizing for 2S, the heating medium regulating valve circuit mode is switched to automatic, and the last automatic mode flow setting value is restored.

17. The control method of a polysilicon distillation process control system according to claim 10, characterized in that: The first-stage tower (1) further comprises an automatic feed control, comprising the following steps: S201: Setting parameters: Setting the feed set value adjustment interval of the PID loop of the feed regulating valve I; Setting the upper and lower limits of the feed flow set value in the automatic mode of the PID loop of the feed regulating valve I; Setting the upper limit, upper limit, lower limit and lower limit of the liquid level of the raw material tank (13); S202: The feed regulating valve I and the feed flow rate are automatically controlled in a single loop, and the PID loop action form is a reaction; the feed flow rate of the distillation tower is monitored in real time by the flow meter Ib, and when there is a positive deviation between the real-time feed flow rate value and the set flow rate value, the feed regulating valve I reduces the output opening to automatically adjust the feed flow rate value; when there is a negative deviation between the real-time feed flow rate value and the set flow rate value, the feed regulating valve I increases the output opening to automatically adjust the feed flow rate value; when it is necessary to reduce the output opening of the feed regulating valve I and the feed flow rate set value reaches the lower limit, no adjustment is made; when it is necessary to increase the output opening of the feed regulating valve I and the feed flow rate set value reaches the upper limit, no adjustment is made; S203: When the liquid level of the raw material tank (13) is ≥ the upper limit and the liquid level is < the upper and lower limits, the feed flow setting value of the feed regulating valve I PID loop is increased by SP1; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments; S204: When the liquid level of the raw material tank (13) is greater than the lower limit and the liquid level is less than or equal to the lower limit, the feed flow setting value of the feed regulating valve I PID loop is reduced by SP1; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments; S205: When the liquid level of the raw material tank (13) is ≥ the upper limit, the feed flow setting value of the feed regulating valve I PID loop is increased by SP2; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments; S206: When the liquid level of the raw material tank (13) is less than or equal to the lower limit, the feed flow setting value of the feed regulating valve I PID loop is reduced by SP2; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments.

18. The control method of a polysilicon distillation process control system according to claim 10, characterized in that: The first-stage tower (1) further comprises automatic temperature control in the tower, comprising the following steps: S301: Setting parameters: Setting the temperature setting value adjustment interval of the heating medium regulating valve PID loop; Setting the upper and lower limits of the temperature setting value in the automatic mode of the heating medium regulating valve PID loop; Setting the upper upper limit, upper limit, lower lower limit and lower limit of the medium temperature of the first-stage tower (1); S302: When the medium temperature of the first-stage tower (1) is ≥ the upper limit and the medium temperature is < the upper limit, the temperature setting value of the heating medium control valve PID loop is increased by SP1; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments; S303: When the medium temperature of the first-stage tower (1) is greater than the lower limit and the medium temperature is less than or equal to the lower limit, the temperature setting value of the heating medium regulating valve PID loop is reduced by SP1; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments; S304: When the medium temperature of the first-stage tower (1) is ≥ the upper limit, the temperature setting value of the heating medium control valve PID loop is increased by SP2; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments; S305: When the medium temperature of the first-stage tower (1) is ≤ the lower limit, the temperature setting value of the steam control valve PID loop is reduced by SP2; after the adjustment, after the adjustment interval time, the program continues to make real-time judgments.

19. The control method of a polysilicon distillation process control system according to claim 10, characterized in that: The distillation tower also includes an automatic reflux ratio adjustment control, which automatically adjusts the reflux ratio according to the extraction flow rate at the top of the distillation tower to ensure the stability of the reflux of the distillation tower, ensure the distillation effect, and reduce energy consumption; including: S401: Input reflux ratio setting value; S402: The flow setting value of the reflux regulating valve II of the distillation tower is automatically adjusted to the product of the reflux ratio setting value and the tower top extraction flow rate; S403: The PID control loop of the reflux regulating valve II acts in a reverse manner; the real-time value of the top tower reflux flow is monitored in real time by flow meter IIc. When there is a positive deviation between the real-time value of the reflux flow and the set value of the reflux flow, the reflux regulating valve II reduces the output opening to automatically adjust the reflux flow; when there is a negative deviation between the real-time value of the reflux flow and the set value of the reflux flow, the reflux regulating valve II increases the output opening to automatically adjust the reflux flow; so that the reflux flow value of the distillation tower is basically stable and maintained at the set value.

20. The control method of a polysilicon distillation process control system according to claim 10, characterized in that: The six-stage tower (6) further includes an automatic slag discharge control system for the tower bottom, including the following steps: S501: setting the material receiving amounts of the two slag mixing tanks (16) respectively; S502: judging the slag discharge conditions of the synthetic distillation six-stage tower (6), including: when the liquid level of one of the slag mixing tanks (16) is less than 54%, the pressure is less than 0.2 MPa, and the vent shut-off valve IV is in an open state, discharging slag and feeding materials to the slag mixing tank (16); when both slag mixing tanks (16) meet the above conditions, discharging slag and feeding materials to the slag mixing tank (16) with a higher liquid level; when both slag mixing tanks (16) do not meet the above conditions, waiting for the slag mixing tank (16) to meet the material receiving conditions; S503: when one of the slag mixing tanks (16) meets the slag discharge condition described in S502, the nitrogen shut-off valve IV of the slag mixing tank (16) that meets the slag discharge condition is closed, the vent shut-off valve IV of the slag mixing tank (16) that meets the slag discharge condition is opened, the feed shut-off valve IVa of the slag mixing tank (16) that does not meet the slag discharge condition is closed, and the timing RET1 is started; After the above-mentioned shut-off valve is fed back to the right position, the feed shut-off valve IVa of the slag mixing tank (16) that meets the slag discharge conditions is opened, and the timing RET2 is started; When the liquid level of the slag mixing tank (16) that meets the slag discharge conditions rises by more than the set material receiving amount, the feed cut-off valve IVa of the mixing tank is closed; When RET2 counts down to 30 minutes, and the feed cut-off valve of the slag mixing tank (16) that meets the slag discharge conditions is not closed and is still feeding, it will prompt: the slag discharge of the synthetic distillation 6-stage tower (6) has timed out, please confirm; S504: When the RET1 timing reaches 160 minutes, steps S502-S503 are repeated. When both slag mixing tanks (16) do not meet the material collection conditions, the circulation conditions are not met, and a prompt is given: the slag discharge conditions of the 6-stage tower (6) are not met.

21. The control method of a polysilicon distillation process control system according to claim 10, characterized in that: The slag mixing tank (16) includes an automatic discharge control, comprising the following steps: S601: setting the discharge amounts of the two slag mixing tanks (16) respectively; S602: Determine the discharge conditions of the slag mixing tank (16): When the liquid level of one of the slag mixing tanks (16) is greater than 65% and the liquid level of the other slag mixing tank (16) is less than or equal to 65%, the slag mixing tank (16) with a liquid level greater than 65% discharges material; When the liquid levels of the two slag mixing tanks (16) are both greater than 65%, the slag mixing tank (16) with the higher liquid level discharges the material; When the liquid levels of the two slag mixing tanks (16) are both ≤65%, the slag mixing tank (16) with a liquid level greater than 54% is discharged; When the liquid levels of the two slag mixing tanks (16) are both ≤65%, and when the liquid levels of the two slag mixing tanks (16) are both >54%, the slag mixing tank (16) with the higher liquid level discharges the material; When the liquid levels of the two slag material mixing tanks (16) are both ≤65%, and when the liquid levels of the two slag material mixing tanks (16) are both ≤54%, the liquid level conditions are re-judged; S603: Determine the slag material mixing tank (16) to be discharged according to the discharge conditions in step S602, and close the venting cut-off valve IV and the feed cut-off valve IVa of the slag material mixing tank (16); S604: real-time monitoring of the pressure in the slag mixing tank (16) for discharging material through the pressure sensor IV, when the pressure is ≥0.6MPa, executing the next step; when the pressure is <0.6MPa, opening the nitrogen shut-off valve IV of the slag mixing tank (16) for discharging material and charging the pressure to 0.6MPa, closing the nitrogen shut-off valve IV, and executing the next step; S605: Determine the discharge path: by default, the discharge conditions are confirmed starting from the slurry process I (191) each time; Material receiving conditions of slurry process I: the feed cut-off valves IVb of the two material receiving tanks of the feed process I meet an open state, the discharge cut-off valve IV between the discharge slag mixing tank (16) and the slurry process II (192) is closed, and the discharge cut-off valve IV between the discharge slag mixing tank (16) and the slurry process I (191) is opened; Material receiving conditions of slag slurry process II: the feed cut-off valves IVb of the two material receiving tanks of the feed process II meet an open state, the discharge cut-off valve IV between the discharge slag material mixing tank (16) and the slag slurry process I (191) is closed, and the discharge cut-off valve IV between the discharge slag material mixing tank (16) and the slurry process II (192) is opened; S606: starting to discharge, when the discharge amount of the slag material stirring tank (16) is greater than the set value or the liquid level in the slag material stirring tank (16) is less than 15%, closing the discharge cut-off valve IV and the nitrogen cut-off valve IV of the slag material stirring tank (16); S607: After closing the discharge cut-off valve IV and the nitrogen cut-off valve IV, the clean liquid cut-off valve of the discharge slag mixing tank (16) is opened for flushing, and the timing is started; when the 300 s timing is up, the clean liquid cut-off valve IV of the discharge slag mixing tank (16) is closed, and the venting cut-off valve IV is opened; S608: During the discharging process, the pressure of the slag mixing tank (16) is maintained between 0.55 and 0.6 MPa. During the discharging process, if the feed cut-off valves IVb of the two receiving tanks of the slurry process I (191) or the slurry process II (192) are both closed, an alarm is triggered. After confirmation by the main control, the discharging path is re-confirmed. During the discharging process, if the feed cut-off valves IVb of the two receiving tanks of any slurry process are both closed, an alarm is triggered.

22. The control method of a polysilicon distillation process control system according to claim 10, characterized in that: The reflux tank (7) further comprises an automatic liquid level adjustment control of the reflux tank (7), comprising the following steps: S701: Setting parameters: setting the interval time, setting the upper limit of the flow setting value of the tower top extraction regulating valve Ⅱb circuit, setting the lower limit of the flow setting value, setting the upper limit, upper limit, lower limit and lower limit of the liquid level of the reflux tank (7); When the liquid level in the reflux tank (7) is greater than or equal to the upper limit or less than or equal to the lower limit, the flow rate of the top extraction regulating valve Ⅱb of the distillation tower is set to the adjustment value SP1; When the liquid level in the reflux tank (7) is greater than or equal to the upper limit or less than or equal to the lower limit, the flow rate of the top extraction regulating valve Ⅱb of the distillation tower is set to the adjustment value SP2; S702: When the liquid level of the reflux tank (7) is greater than or equal to the upper limit and the liquid level is less than the upper and lower limits, the flow setting value of the distillation tower top extraction regulating valve Ⅱb loop is increased by SP1; after adjustment, the stable interval time, the program continues to make real-time judgments; When the liquid level in the reflux tank (7) is greater than the lower limit and the liquid level is less than or equal to the lower limit L, the flow setting value of the distillation tower top extraction regulating valve Ⅱb loop is reduced by SP1; after adjustment, the stable interval time, the program continues to make real-time judgments; S703: When the liquid level of the reflux tank (7) is greater than or equal to the upper limit, the set value of the flow rate of the IIb loop of the distillation tower top extraction regulating valve is increased by SP2; after adjustment, the interval time is stabilized and the program continues to make real-time judgments; When the liquid level in the reflux tank (7) is less than or equal to the lower limit, the set value of the flow rate of the distillation tower top extraction regulating valve Ⅱb loop is reduced by SP2; after adjustment, the stable interval time is T1, and the program continues to make real-time judgments.

23. The control method of a polysilicon distillation process control system according to claim 10, characterized in that: The tail gas condensation device includes a tail gas venting condensate system feeding control method, including: S801: When the liquid level of the tail gas condensate tank (21) is higher than 65%, the condensate pump is automatically started, and the opening of the production regulating valve III is opened to 70%; after 10 seconds, the production regulating valve III mode is switched to automatic, and the production flow rate is set. The production regulating valve III automatically adjusts the opening according to the deviation between the real-time value of the production flow rate and the set value; S802: When the liquid level of the tail gas condensate tank (21) is lower than 20%, the condensate pump automatically stops running and the extraction regulating valve III is closed; S803: During operation, if the condensate pump current is lower than 8A and lasts for 10 seconds, the condensate pump stops running and the production regulating valve III is closed.

24. The control method of a polysilicon distillation process control system according to claim 10, characterized in that: The control method of the polysilicon distillation process control system also includes automatic material pressing control of the liquid guiding tank (22), including: S901: When the liquid level of the spraying liquid tank (22) is higher than the set value, first close the feed cut-off valve III, and then close the vent cut-off valve III; Open the discharge cut-off valve III to discharge the tail gas condensate tank (21), and then open the nitrogen cut-off valve III to pressurize the guide liquid tank (22); S902: When the liquid level of the spraying liquid tank (22) is lower than the set value, first close the nitrogen cut-off valve III, then close the discharge cut-off valve III; open the air cut-off valve III for 10 seconds, and then open the feed cut-off valve III; S903: in step S901, the timing starts after the nitrogen shut-off valve III of the liquid guide tank is opened. When the pressure is charged for more than 3 minutes, an alarm is given, and the program automatically opens the vent shut-off valve first for 10 seconds, and then opens the feed shut-off valve. S904: When the number of drainage reaches 2 times within 60 minutes, an alarm will be issued to prompt the main control that the number of drainage times is too many.

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