Automatic control system and automatic control method of four-washing filter press for producing titanium dioxide by sulfuric acid method

Abstract

The invention discloses an automatic control system of a four-washing filter press for producing titanium dioxide by a sulfuric acid method, which is adaptive to medium-scale high-purity titanium dioxide production, adopts the four-washing filter press as a core, and consists of a functional unit, a detection unit and a DCS (Distributed Control System) control unit, the system comprises an initialization module, a feeding module, a multi-stage washing module, a squeezing and blow-drying module, a resetting module and an interlocking protection module, full-process automation is achieved, and the system has the functions of safety interlocking, overtime protection and fault alarm. The system can guarantee stable product quality, remarkably improve the production efficiency, optimize wastewater recycling and reduce the comprehensive production cost, is safe and reliable in operation, and is suitable for industrial production of medium-scale high-purity titanium dioxide.

Description

Technical Field

[0001] This invention relates to the field of chemical automation control technology, specifically to an automatic control system and method for a four-wash filter press in the sulfuric acid process for titanium dioxide production. It is applicable to the full-process automated control scenario of metatitanic acid filter press, multi-stage water washing, pressing and drying, and wastewater recovery in the sulfuric acid process for titanium dioxide production. Background Technology

[0002] In the sulfuric acid process for titanium dioxide production, the metatitanic acid produced by hydrolysis needs to be filtered and washed multiple times to remove soluble impurities. The four-stage washing filter press is the core equipment in this process. Currently, the automation level of this process is generally low in the industry, mainly relying on on-site manual operation or partial remote manual control, which has the following prominent drawbacks: Unstable quality control: Manual operation makes it difficult to accurately control the amount of metatitanic acid fed and the washing time at each stage, which can easily lead to insufficient or excessive washing, causing fluctuations in product whiteness and purity, and failing to meet the quality consistency requirements of high-end applications. Safety and equipment risks are prominent: The operation sequence is complex (such as opening valves before starting pumps, or closing valves in a specific order). Manual operation is prone to reversing or omitting steps, which may lead to safety hazards such as pipeline pressure buildup, pump dry running, equipment damage and material leakage. Low production efficiency and high labor intensity: Manual monitoring of material feeding is prone to material shortages, affecting the continuity of production. Moreover, the entire process requires manual intervention, making it impossible to achieve continuous cyclical operation, consuming a large amount of manpower, and limiting production efficiency. Serious waste of resources: Manual operation makes it difficult to accurately control water consumption, and the lack of a scientific wastewater classification and recycling mechanism leads to low water utilization and increased production costs.

[0003] In response to the aforementioned technical problems caused by manual operation in existing technologies, there is an urgent need to develop a fully automated and precise control solution to break through industry production bottlenecks and improve the level of intelligence and core competitiveness of high-purity titanium dioxide production. Summary of the Invention

[0004] This invention aims to overcome the shortcomings of existing technologies and provide an automatic control system and method for a four-wash filter press in the sulfuric acid process for titanium dioxide production. This system achieves full-process automation, reduces manual intervention and labor intensity; precisely controls key process parameters such as feed rate, washing time, and pressing intensity to improve product quality stability; eliminates the risk of misoperation through safety interlock logic, ensuring production safety and equipment integrity; optimizes water resource utilization, achieves wastewater classification and recycling, and reduces production costs; and enables continuous cyclic operation to improve production efficiency and equipment utilization.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This system, centered on a distributed DCS control system, integrates functional units such as feeding, washing, pressing and drying, and wastewater recovery to form a closed-loop automated control system, specifically including: (1) Core equipment Four-wash filter press (A): As the core container for metatitanic acid filtration and water washing, it is suitable for the solid-liquid separation and impurity removal requirements of metatitanic acid materials and has a pressure holding signal output function.

[0006] (2) Functional Unit Material storage tank: It consists of a feed pump and a feed valve connected in series. The feed pump is a variable frequency metering pump with a flow rate adjustment range that can be adapted to production needs. The valve is a pneumatic shut-off valve with a response time of ≤3 seconds. Together, they can achieve precise delivery and start-stop control of metatitanic acid materials. The water washing unit includes a reuse water storage tank, a desalination storage tank, and an angle washing subsystem, forming a three-stage cleaning structure of "rough washing - fine washing - intensive washing". Recycled water storage tank: It consists of a recycled water pump, a recycled water washing valve, and a level gauge for the recycled water storage tank. The recycled water pump is a corrosion-resistant centrifugal pump, which uses recycled water to perform preliminary impurity removal on the filter cake. Desalination storage tank: It consists of a desalination water pump and a desalination water washing valve. The desalination water pump adopts a high-precision metering pump to ensure the accurate delivery of high-purity desalination water and achieve deep cleaning of filter cake. Angle washing subsystem: including left angle washing valve and right angle washing valve, adopts targeted flushing design to solve the problem of incomplete local cleaning of filter cake; Press water storage tank and compressed air source: It consists of a press pump, a press water inlet valve, a press water return valve and a compressed air inlet valve. The press pump is a high-pressure plunger pump and the compressed air inlet valve is equipped with a flow regulation function, which work together to realize mechanical pressing of filter cake and purging of residual water. Wastewater tank: includes left outlet valve, right outlet valve, wastewater valve and recycling inlet valve. The valves are made of corrosion-resistant materials and are suitable for the conveying environment of filtrate and wastewater, realizing the control of filtrate discharge path and wastewater classification and recycling. The detection unit includes a flow meter and a level gauge. The flow meter is an electromagnetic flow meter with an accuracy of ≤±0.5%, used to detect the feed flow rate of metatitanic acid. The level gauge uses a level sensor with a measurement range adapted to the volume of the recycled water storage tank, providing real-time feedback on the recycled water level. DCS Control Unit: Utilizing an industrial-grade distributed control system (such as the Siemens S7-400 series), it establishes communication connections with pumps and valves of each functional unit via wired cables (such as Profibus-DP bus) or wireless communication (such as 5G industrial modules). It possesses functions such as signal acquisition, logic operation, and command output. The DCS pre-stores control programs and safety interlock logic, receives pressure holding signals from the four-wash filter press, flow signals from the flow meter, and level signals from the level gauge, and automatically controls the sequence and duration of actions of each actuator. During the demineralized water washing stage, the DCS can automatically switch between wastewater discharge and recycling modes to achieve water resource recycling.

[0007] On the other hand, the automatic control method is based on the aforementioned automatic control system. Driven by a DCS program, it realizes the fully automated execution of the entire process of "initialization-feeding-multi-stage water washing-pressing and drying-reset cycle". The specific steps are as follows: (1) Program initialization The automation program is started. The DCS system self-checks the status of each unit (pump, valve, sensor). After confirming that there are no faults, it enters standby mode and waits for the pressure holding signal of the four-wash filter press to be triggered.

[0008] (2) Feeding stage When the pressure holding signal of the four-wash filter press is ON, the feeding process is triggered; 20 seconds after the pressure holding signal is ON (ensuring the filter press is stable and ready), the DCS sends a command to open the left outlet valve, right outlet valve, and wastewater valve, thus opening the filtrate discharge channel. Open the feed valve, and start the feed pump after 5 seconds to deliver metatitanic acid material to the four-wash filter press. The flow meter collects the cumulative feed volume in real time and feeds it back to the DCS. When the set volume is reached, the DCS commands the feed pump to stop. The feeding phase ends when the feed pump stops for 5 seconds and the feed valve is closed.

[0009] (3) Multi-stage washing stage After the feed valve is closed for 5 seconds, the recovery water washing valve is opened, and after another 5 seconds, the recovery water pump is started to use the recovery water for initial cleaning. When the level gauge of the reuse water storage tank detects that the liquid level is lower than the set value of two, the recycling water pump is stopped, and the recycling water washing valve is closed after 5 seconds. After the recovery water washing valve is closed for 5 seconds, the demineralized water washing valve is opened, and after another 5 seconds, the demineralized water pump is started for deep cleaning. When the demineralized water pump runs for one time, the recovery water inlet valve is opened, and the wastewater valve is closed after 5 seconds, and the clearer wastewater is recovered to the reuse storage tank. When the demineralized water pump reaches the set time value of two, open the left corner wash valve, close the demineralized water wash valve after 5 seconds, and close the left outlet valve to strengthen the rinsing of the left side of the filter cake. When the demineralized water pump runs to the set time value of three, open the left outlet valve and the right corner wash valve. After 5 seconds, close the left corner wash valve and the right outlet valve to strengthen the rinsing of the right side of the filter cake. When the demineralized water pump runs for four hours, stop the demineralized water pump and close the right corner wash valve after 5 seconds. After the right corner water valve is closed for 5 seconds, open the right outlet valve to end the water washing stage.

[0010] (4) Pressing and drying stage After the right outlet valve is opened for 5 seconds, the press return valve is closed. After another 5 seconds, the press inlet valve is opened, and the press pump is started to mechanically press the filter cake. When the pressing pump runs for five hours, stop the pressing pump. After 5 seconds, open the pressing return water valve and close the pressing inlet water valve. After the water inlet valve is closed for 5 seconds, open the compressed air inlet valve and introduce compressed air to blow away the residual moisture. When the compressed air intake valve has been open for six hours (the set time value), the valve is closed, and the pressing and drying stages end.

[0011] (5) System Reset After the compressed air inlet valve is closed for 5 seconds, the wastewater valve is opened, and after 5 seconds, the recovery water inlet valve is closed. The program ends 5 seconds after the inlet valve is closed, the system returns to its initial state, and waits for the next pressure holding signal to trigger, thus achieving continuous cycle operation.

[0012] The beneficial effects of this invention are: 1. High degree of automation throughout the entire process: The DCS enables one-button start and automatic cycle from feeding, washing, pressing, drying and cleaning to resetting, without the need for continuous manual intervention. The number of operators in a single process can be reduced by more than 60%, and the labor intensity is greatly reduced. 2. Significantly improved product quality stability: Automated control ensures that the repeatability of key parameters such as feed rate, washing time, and pressing intensity is ≤±1%, product whiteness is ≥95%, purity is ≥99.8%, and batch-to-batch quality fluctuation is ≤±0.5%, which is far better than the ±3% fluctuation range of manual operation. 3. Strong production safety and equipment support capabilities: Built-in safety interlock logic such as "open valve before pump" and "stop pump before valve" eliminates problems such as pipeline pressure buildup and pump dry running caused by misoperation, reducing the equipment failure rate to below 1% and the risk of material leakage to 0. 4. Improved production efficiency and resource utilization: The system can operate continuously for 24 hours, reducing the production time per batch from 4 hours with manual operation to 2.5 hours, and increasing daily output by 60%; the wastewater recycling rate reaches over 80%, water consumption is reduced by 30%, and the overall production cost is reduced by over 20%. 5. Strong adaptability and expandability: Each set value (flow rate, time, liquid level) can be flexibly adjusted through the DCS interface to adapt to the production needs of high-purity titanium dioxide with different purities and yields; the control logic can be transferred to similar chemical pressure filtration and washing processes, making it highly practical. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the system structure of the present invention.

[0014] Reference numerals in the attached drawings: 100, four-wash filter press; 200, material storage tank; 300, recycled water storage tank; 400, press water storage tank; 500, demineralized water storage tank; 600, wastewater tank; 2. Left outlet valve; 3. Right outlet valve; 4. Wastewater valve; 5. Feed valve; 6. Feed pump; 7. Feed flow meter; 8. Recycled water washing valve; 9. Recycled water pump; 10. Level gauge; 11. Demineralized water washing valve; 12. Demineralized water pump; 13. Recycled water inlet valve; 14. Left corner washing valve; 15. Right corner washing valve; 16. Press return water valve; 17. Press inlet water valve; 18. Press pump; 19. Compressed air inlet valve. Detailed Implementation

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in conjunction with the accompanying drawings and descriptions of the embodiments or the prior art. Obviously, the following description of the structure of the accompanying drawings is only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0016] Example: like Figure 1 As shown, this embodiment provides an automatic control system for a four-wash filter press in the sulfuric acid process for titanium dioxide production. The system uses a 10m³ four-wash filter press as the core equipment, adapting to the needs of medium-scale high-purity titanium dioxide production. The selection and connection relationships of each component are as follows: I. Core Equipment Four-wash filter press 100: Model XAZG100 / 1250-U, filtration area 100m², working pressure 0.6-1.2MPa, material is corrosion-resistant stainless steel, equipped with pressure holding sensor, can output switch pressure holding signal.

[0017] II. Selection and Connection of Functional Unit Components (1) Material storage tank Feed pump 6: Variable frequency metering pump, model GM-80, flow range 5-15m³ / h, head 40m, power 7.5kW, sealing material PTFE, corrosion resistant; Feed valve 5: Fluorine-lined pneumatic shut-off valve, model Q641F46-16C, nominal diameter DN50, response time ≤2 seconds; Connection relationship: The inlet of feed pump 6 is connected to the metatitanic acid raw material tank, and the outlet is connected to feed valve 5 through a pipeline. The outlet of feed valve 5 is connected to the feed port of the four-wash filter press 100.

[0018] (2) Water washing unit Reclaimed water storage tank 300: The reclaimed water pump 9 is a corrosion-resistant centrifugal pump, model IHF50-32-160, with a flow range of 5-15 m³ / h and a head of 32 m; the reclaimed water washing valve 8 is the same type as the feed valve; the level gauge 10 of the reclaimed water storage tank has a volume of 5 m³ and is equipped with a level sensor (model CYW11), with a measurement range of 0-5 m and an accuracy of ±0.5%; Desalination storage tank 500: The desalination water pump 12 is a high-precision metering pump, model JXM-A100, with a flow range of 3-10 m³ / h and an accuracy of ±0.3%; the desalination water washing valve 11 is the same type as the feed valve. To; Angle Washing Subsystem: Left angle wash valve 14 and right angle wash valve 15 are both fluoropolymer-lined pneumatic ball valves, model Q641F46-16C, nominal diameter DN25; Connection relationship: The inlet of the recovery water pump 9 is connected to the level gauge 10 of the return water storage tank 300, and the outlet is connected to the recovery water inlet of the four-wash filter press 100 through the recovery water wash valve 8; The inlet of the demineralized water pump 12 is connected to the demineralized water pipeline network, and the outlet is connected to the demineralized water inlet of the four-wash filter press 100 through the demineralized water wash valve 11; The left angle wash valve 14 and right angle wash valve 15 are respectively installed on the left and right sides of the four-wash filter press 100 for targeted flushing.

[0019] (3) Pressed water storage tank and compressed air source Press pump 18: High-pressure plunger pump, model 3WZ-40 / 10, flow rate 40L / min, working pressure 10MPa; Press inlet valve 17 and press return valve 16: Both are high-pressure pneumatic shut-off valves, model Q641N-40, nominal diameter DN32; Compressed air inlet valve 19: Pneumatic diaphragm regulating valve, model ZMBP-40, nominal diameter DN40, equipped with a flow controller; Connection relationship: The inlet of press pump 18 is connected to the high-pressure water pipeline, and the outlet is connected to the press inlet of the four-wash filter press 100 through the press inlet valve 17; One end of the press return valve 16 is connected to the press return port of the four-wash filter press 100, and the other end is connected to the return water pipeline; The inlet of compressed air inlet valve 19 is connected to the compressed air pipeline (pressure 0.6-0.8MPa), and the outlet is connected to the air inlet of the four-wash filter press 100.

[0020] (4) Wastewater tank Left outlet valve 2, right outlet valve 3, and wastewater valve 4: all are fluoropolymer-lined pneumatic shut-off valves, model Q641F46-16C, nominal diameter DN50; recovery inlet valve 13: electric regulating valve, model ZDLP-40, nominal diameter DN40, flow regulation accuracy ±0.5%; connection relationship: left outlet valve 2 and right outlet valve 3 are respectively installed at the left and right outlets of the four-wash filter press 100. The outlets are connected to two branches through pipelines. One branch connects to wastewater valve 4 to the wastewater treatment system, and the other branch connects to recovery inlet valve 13 to the level gauge 10 of the recycled water storage tank 300.

[0021] (5) Detection unit Feed flow meter 7: Electromagnetic flow meter, model LDG-50, range 0-20m³ / h, accuracy ±0.5%, output 4-20mA analog signal; Level gauge 10: Submersible level sensor, model CYW11, measuring range 0-5m, accuracy ±0.5%, output 4-20mA analog signal; Installation position: Feed flow meter 7 is installed on the pipeline between feed pump 6 and feed valve 5; Level gauge 10 is submersibly installed at the bottom of reuse water storage tank 300, with the sensor probe located below the lowest liquid level in the tank.

[0022] (6) DCS control unit Selection: Siemens S7-400 series DCS, equipped with CPU414-3PN / DP, SM321 digital input module (16 points), SM322 digital output module (16 points), and SM331 analog input module (8 points); Communication connection: The DCS establishes a wired connection with the control terminals and status feedback terminals of each pump and valve via Profibus-DP bus, with a communication rate of 12Mbit / s; Analog signals from feed flow meter 7 and level gauge 10 are connected to the SM331 module; Operating interface: Equipped with an industrial touch screen (model TP177B) for parameter setting, status monitoring, and emergency manual intervention.

[0023] III. Control Program and Interlocking Logic Settings 1. Control program writing The control program was written using Step7 software. The program structure includes an initialization module, a feeding control module, a washing control module, a pressing and drying control module, a reset module, and an interlock protection module. Each module is called in the form of a function block (FB), and the core logic is consistent with the control method steps of this invention.

[0024] 2. Key Interlocking Logic Safety Interlock: Before starting any pump, the corresponding pre-valve must be opened and feedback must be in place (delay 5 seconds); after the pump stops, the corresponding post-valve must close after a 5-second delay to avoid pipeline pressure surges; Timeout Protection: Feed pump 6, recovery water pump 9, demineralized water pump 12, and pressing pump 18 are all equipped with timeout protection (example values ​​are: 360S, 240S, 1800S, 900S respectively). If the running time exceeds the set value and the corresponding control conditions are not met, the machine will automatically stop and trigger an audible and visual alarm; Fault Alarm: When a valve does not open or close as instructed or a sensor does not provide signal feedback, the DCS touchscreen displays the fault location and type, suspends the current process, and waits for operator intervention.

[0025] 3. Example of setpoint parameters

[0026] IV. Specific Implementation Steps Taking a single batch of 10m³ metatitanic acid treatment as an example, the specific implementation process of this invention is as follows: 1. Program Initialization The operator clicks the "Automatic Start" button on the DCS touchscreen, and the system enters the initialization state. The DCS self-checks the status of each pump, valve, and sensor. After confirming that there are no faults, the touchscreen displays "Ready" and waits for the pressure holding signal.

[0027] 2. Feeding stage After the four-wash filter press 100 completes the unloading of the previous batch, it enters the pressure holding state and outputs a pressure holding signal of ON. 20 seconds after the pressure holding signal is triggered, the DCS commands to open the left outlet valve 2, the right outlet valve 3, and the wastewater valve 4. After 2 seconds, the valve status feedback is in place. The DCS opens the feed valve 5, and after 5 seconds, the feed pump 6 is started with a flow rate set to 10 m³ / h. The feed flow meter 7 provides real-time feedback on the feed amount. When the accumulated amount reaches 10 m³, the DCS commands to stop the feed pump 6. 5 seconds after the feed pump stops, the feed valve 5 is closed, and the feeding stage ends (takes approximately 600 seconds).

[0028] 3. Multi-stage washing process After the feed valve closes for 5 seconds, the DCS opens the recovery water washing valve 8, and after another 5 seconds, starts the recovery water pump 9 with a flow rate set to 10 m³ / h. When the level gauge 10 of the reuse storage tank 300 detects that the level has dropped to 0.5 m³, the DCS commands the recovery water pump 9 to stop, and after another 5 seconds, closes the recovery water washing valve 8 (the recovery water washing takes approximately 300 seconds). After the recovery water washing valve closes for 5 seconds, the DCS opens the demineralized water washing valve 11, and after another 5 seconds, starts the demineralized water pump 12 with a flow rate set to 5 m³ / h. When the demineralized water pump has been running for 300 seconds (time setpoint one), the DCS opens the recovery inlet valve 13, and after another 5 seconds, closes the wastewater valve 4, switching the wastewater to recovery mode. The demineralized water pump runs for 60 seconds. At 0 seconds (time setting value two), the DCS opens the left corner wash valve 14, and after 5 seconds closes the demineralized water wash valve 11 and the left outlet valve 2, performing enhanced rinsing on the left side (time 300 seconds); when the demineralized water pump runs for 900 seconds (time setting value three), the DCS opens the left outlet valve 2 and the right corner wash valve 15, and after 5 seconds closes the left corner wash valve 14 and the right outlet valve 3, performing enhanced rinsing on the right side (time 300 seconds); when the demineralized water pump runs for 1200 seconds (time setting value four), the DCS commands the demineralized water pump 12 to stop, and after 5 seconds closes the right corner wash valve 15; after the right corner wash valve closes for 5 seconds, the DCS opens the right outlet valve 3, ending the water washing stage (total time 1200 seconds).

[0029] 4. Pressing and drying stage After the right outlet valve is opened for 5 seconds, the DCS closes the press return water valve 16, and after another 5 seconds, opens the press inlet water valve 17 and starts the press pump 18. When the press pump has been running for 600 seconds (time setting value five), the DCS commands the press pump 18 to stop, and after another 5 seconds, opens the press return water valve 16 and closes the press inlet water valve 17 (pressing time is 600 seconds). After the press inlet water valve is closed for 5 seconds, the DCS opens the compressed air inlet valve 19 and adjusts the flow rate to 10 m³ / min to purge residual moisture. When the compressed air inlet valve is open for 300 seconds (time setting value six), the DCS closes the valve, and the pressing and drying stages end (time is 300 seconds).

[0030] 5. System Reset After the compressed air intake valve is closed for 5 seconds, the DCS opens the wastewater valve 4 and closes the recovery water intake valve 13 after 5 seconds. After the recovery water intake valve is closed for 5 seconds, the DCS sends a "process completed" signal, the touch screen displays "batch ended", and the system returns to the initial state, waiting for the next batch pressure holding signal (reset takes 10 seconds).

[0031] V. Verification of Implementation Results Through the configuration and operation of this embodiment, the following technical effects are achieved: Product quality: The whiteness of a single batch of product is stable at 95.5%-96.0%, and the purity is ≥99.85%, with quality fluctuations between batches of only ±0.3%; Production efficiency: The total time for a single batch is 2710 seconds (approximately 45 minutes), which is 73% shorter than the 4 hours of manual operation, and the daily output increases from 12 batches to 32 batches; Safety performance: No safety accidents such as pipeline pressure buildup, pump dry running, or material leakage occurred during the implementation period, and the equipment failure rate is 0%; Cost control: The wastewater recycling rate reaches 85%, water consumption per ton of product is reduced by 35%, labor costs are reduced by 60%, and the overall production cost is reduced by 22%.

[0032] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An automatic control system for a four-wash filter press in the sulfuric acid process for titanium dioxide production, characterized in that, include: Four-wash filter press, used for the pressure filtration and water washing of metatitanic acid; The material storage tank, including a feed pump and a feed valve connected thereto, is used to supply metatitanic acid material to the four-wash filter press; The water washing unit includes a reuse water storage tank and a desalination storage tank. The reuse water storage tank includes a recovery water pump, a recovery water washing valve and a recovery water inlet valve. The desalination storage tank includes a desalination water pump and a desalination water washing valve, which are used to perform multi-stage cleaning of the filter cake. The press water storage tank and compressed air source, including the press pump, press water inlet valve and compressed air inlet valve, are used to press and dry the filter cake; The DCS control unit is communicatively connected to the pumps and valves in the material storage tank, water washing unit, press water storage tank and compressed air source. It is used to receive the pressure holding signal of the four-wash filter press, the flow signal of the flow meter and the liquid level signal of the liquid level gauge, and automatically control the action sequence and duration of each actuator according to the preset program.

2. The automatic control system according to claim 1, characterized in that, The water washing unit also includes an angle washing subsystem, which includes a left angle washing valve and a right angle washing valve, for localized enhanced cleaning of the filter cake.

3. The automatic control system according to claim 2, characterized in that, It also includes a wastewater tank, which includes a left outlet valve, a right outlet valve, and a wastewater valve, for controlling the filtrate discharge path and the classified recycling of wastewater.

4. The automatic control system according to claim 3, characterized in that, The DCS control unit is configured to, when performing the demineralized water washing step, first open the wastewater valve to drain the initial wastewater, and after reaching a first set time, switch to open the recovery water inlet valve to recover the later, clearer wastewater, and then close the wastewater valve.

5. The automatic control system according to any one of claims 1-4, characterized in that, The DCS control unit can communicate with each pump and valve via wired or wireless connection.

6. The automatic control system according to claim 1, characterized in that, The flow meter is an electromagnetic flow meter with an accuracy of ≤±0.5%, and the level gauge is a level sensor with a measurement range adapted to the volume of the reuse water storage tank.

7. An automatic control method for a four-wash filter press in sulfuric acid process titanium dioxide production based on the automatic control system described in claim 1, characterized in that, Includes the following steps: Step 0: Initialize the state and start the automation program; Step 1: When the pressure holding signal of the four-wash filter press is ON, proceed to the next process; Step 2: After the pressure holding signal of the four-wash filter press turns ON, proceed to the next step 20 seconds later; Step 3: Open the left outlet valve of the four-wash filter press; Step 4: Open the right outlet valve of the four-wash filter press; Step 5: Open the wastewater valve of the four-wash filter press; Step 6: Open the feed valve of the four-wash filter press; Step 7: After the feed valve of the four-wash filter press has been open for 5 seconds, start the feed pump; Step 8: When the feed flow meter reaches the set volume, stop the feed pump; Step 9: After the feed pump stops running for 5 seconds, close the feed valve; Step 10: After the feed valve is closed for 5 seconds, open the recovery water washing valve; Step 11: After the recovery water washing valve is open for 5 seconds, start the recovery water pump; Step 12: When the level gauge of the recycled water storage tank is lower than the set level value of two, stop the recycled water pump of the four-wash filter press. Step 13: After the recovery water pump of the fourth-wash filter press stops running for 5 seconds, close the recovery water washing valve of the fourth-wash filter press. Step 14: After closing the recovery water washing valve of the fourth washing filter press for 5 seconds, open the demineralized water washing valve of the fourth washing filter press. Step 15: After the demineralized water washing valve of the four-wash filter press has been open for 5 seconds, start the demineralized water pump of the four-wash filter press. Step 16: When the demineralized water pump of the four-wash filter press has been running for one time, open the recovery water inlet valve; Step 17: After the recovery inlet valve is opened for 5 seconds, close the wastewater valve of the four-wash filter press; Step 18: When the demineralized water pump of the four-wash filter press has been running for two time-set values, open the left corner wash valve of the four-wash filter press. Step 19: After opening the left corner wash valve (QF8103A) of the four-wash filter press for 5 seconds, close the demineralized water wash valve of the four-wash filter press. Step 20: After the demineralized water washing valve of the four-wash filter press is closed for 5 seconds, close the left outlet valve of the four-wash filter press; Step 21: When the demineralized water pump of the four-wash filter press has been running for three hours, open the left outlet valve of the four-wash filter press and open the right corner wash valve of the four-wash filter press. Step 22: After opening the right corner inlet valve of the four-wash filter press for 5 seconds, close the left corner inlet valve of the four-wash filter press and close the right outlet valve of the four-wash filter press. Step 23: When the demineralized water pump of the fourth-wash filter press reaches the set time value of four, stop the demineralized water pump of the fourth-wash filter press. Step 24: After the demineralized water pump of the fourth-wash filter press stops running for 5 seconds, close the right corner wash water valve of the fourth-wash filter press; Step 25: After closing the right corner wash valve of the four-wash filter press for 5 seconds, open the right outlet valve of the four-wash filter press. Step 26: After opening the right outlet valve (QF8107A) of the four-wash filter press for 5 seconds, close the press return valve of the four-wash filter press. Step 27: After the press return water valve of the four-wash filter press is closed for 5 seconds, open the press inlet water valve of the four-wash filter press. Step 28: After the pressing water inlet valve of the four-wash filter press is opened for 5 seconds, start the pressing pump of the four-wash filter press; Step 29: When the running time of the pressing pump of the four-wash filter press reaches the time set value of five, turn off the pressing pump of the four-wash filter press. Step 30: After the pressing pump of the four-wash filter press stops running for 5 seconds, open the pressing return water valve of the four-wash filter press. Step 31: After the press return water valve of the four-wash filter press is opened for 5 seconds, close the press inlet water valve of the four-wash filter press. Step 32: After closing the press water inlet valve of the four-wash filter press for 5 seconds, open the compressed air inlet valve of the four-wash filter press. Step 33: When the compressed air inlet valve of the four-wash filter press has been open for six hours, close the compressed air inlet valve of the four-wash filter press. Step 34: After closing the compressed air inlet valve of the four-wash filter press for 5 seconds, open the wastewater valve of the four-wash filter press. Step 35: After closing the wastewater valve of the four-wash filter press for 5 seconds, close the recovery water inlet valve; Step 36: After the water inlet valve is closed for 5 seconds, the program ends and jumps back to step 0.

8. The automatic control method according to claim 7, characterized in that, The time setpoint 1, time setpoint 2, time setpoint 3, time setpoint 4, time setpoint 5, time setpoint 6, as well as the set volume 1 and liquid level setpoint 2, are all adjusted through the DCS control unit.

9. The automatic control method according to claim 7, characterized in that, The time intervals between the opening and closing of each valve and the starting and stopping of each pump are adjusted according to the equipment response speed, with an adjustment range of 1S-10S.

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