A kind of plate-and-frame filter press safety control system, method and plate-and-frame filter press

Abstract

The present application belongs to the technical field of industrial filter equipment control, and particularly relates to a safety control system and method for a plate-and-frame filter press and the plate-and-frame filter press. The system comprises a control unit and a hydraulic unit, a tightness testing unit, a feeding unit, an extrusion unit, a purging unit and a discharging unit connected to the control unit. The control unit receives detection signals and determines whether the preset interlocking condition is met. According to the determination result, a control instruction is outputted, and a multi-stage interlocking control process is executed, including the stages of compression and tightness testing, feeding, extrusion, purging and discharging. The technical scheme of the present application realizes multi-stage pressure interlocking safety control of the plate-and-frame filter press through the functional coupling and multi-signal control of the units, can significantly reduce the risks of material spraying and residual pressure misoperation, improve the safety and reliability of the whole process, and meet the demand for automatic safety interlocking control in the whole process.

Description

Technical Field

[0001] This invention belongs to the field of industrial filtration equipment control technology, and specifically relates to a safety control system, method and plate and frame filter press. Background Technology

[0002] Plate and frame filter presses are commonly used solid-liquid separation equipment. In existing technologies, the process control of plate and frame filter presses typically relies on the sequential logic and timing strategies of PLCs (Programmable Logic Controllers) or relays. Stage switching for pressing, feeding, squeezing, purging, and discharging is driven by single-point pressure or stroke signals, or even by the operator's experience, to meet basic solid-liquid separation and equipment start-up and shutdown requirements. However, existing stage switching methods are mostly based on experience thresholds and fixed time windows, lacking mandatory constraints on cross-stage conditions and a complete safety interlocking closed loop. This makes it difficult to maintain stability and safety under complex operating conditions, material fluctuations, and component aging.

[0003] For example, in terms of filter plate compression and sealing confirmation, traditional solutions often determine that feeding is allowed once a certain oil pressure or a signal is reached, lacking rigid access conditions. This may lead to feeding starting before the filter chamber is airtight, which can easily cause slurry spraying, material leakage, and contamination. During the feeding process, time or single-point pressure is often used as the endpoint criterion, resulting in premature shutdown or filtration tailing and increased energy consumption. At the same time, the real-time suppression of backflow and dry pumping is also insufficient. When the outlet pressure drops, the valve cannot be interlocked to shut off the pump, and the pump is prone to dry running and damage when the extrusion medium is insufficient.

[0004] Furthermore, existing technologies often pose a risk of loosening the plate before the residual pressure during the unloading process is confirmed, and lack a pressurized prohibition mechanism, potentially leading to personal and equipment safety hazards. Additionally, traditional interlocking solutions are mostly localized and decentralized, lacking a continuous multi-level pressure and status interlocking chain. Moreover, the priorities for alarms and responses are unclear, and abnormal branches lack preemptive action, making it difficult to promptly cut off dangerous actions and organize orderly pressure relief. These are the shortcomings of existing technologies.

[0005] In view of this, it is very necessary for the present invention to provide a safety control system, method and plate and frame filter press to solve the above-mentioned defects in the prior art. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing plate and frame filter press control systems, such as the lack of fully automated safety interlock control, resulting in insufficient sealing confirmation, inaccurate determination of the feed endpoint, lack of backflow and dry-pull interlock, and lack of residual pressure protection during discharge. This invention provides a safety control system, method, and plate and frame filter press to solve the aforementioned technical problems.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A safety control system for a plate and frame filter press includes: The control unit is used to receive pressure signals and liquid level signals and output control commands. The pressure signals include oil pressure. The hydraulic unit, connected to the control unit, is used to apply clamping force to the filter plates and to perform pressure relief under the control of the control unit; The sealing test unit, connected to the control unit, is used to fill the filter chamber with medium and perform a sealing test after the filter plates are pressed. The feeding unit, connected to the control unit, is used to feed materials into the filter chamber; The extrusion unit, connected to the control unit, is used to extrude and dehydrate the filter cake after feeding. The purging unit, connected to the control unit, is used to purge and dry the filter cake after extrusion. The unloading unit, connected to the control unit, is used to perform the unloading operation after depressurization is completed; The control unit is configured as follows: It receives detection signals from sensors in the hydraulic unit, feeding unit, testing unit, extrusion unit, purging unit, and unloading unit; Determine whether the preset interlocking conditions are met based on the detection signal; Based on the judgment result, control commands are output to execute a multi-stage interlocking control process, which includes a pressing and testing stage, a feeding stage, a squeezing stage, a purging stage, and a discharging stage.

[0008] By adopting the above technical solution, the control unit, hydraulic unit, testing unit, feeding unit, extrusion unit, purging unit, and unloading unit are functionally coupled under the same control system. The process is triggered and constrained based on the acquisition of pressure signals (including oil pressure) and liquid level signals, constructing a multi-stage interlocking control covering compaction and testing, feeding, extrusion, purging, and unloading. This forms a closed-loop logic centered on "condition fulfillment—action authorization—status monitoring—abnormal interlocking." This achieves conditional access for actions at each stage and sequential consistency across stages, avoiding errors caused by single-point timing, empirical judgment, or local signal distortion. The system effectively mitigates false triggering and crosstalk, ensuring stable operation of the equipment under varying material viscosities, filter cloth conditions, and environmental disturbances. Furthermore, it enables unified judgment and priority management of critical signals within a single strategic framework, guaranteeing that actions involving personal and equipment safety are placed under high-priority control and allowing for flexible switching of non-critical processes. This significantly reduces risks such as material spraying, residual pressure misoperation, backflow impact, and abnormal dry running, enhancing the overall safety, reliability, and maintainability of the process. Simultaneously, it reduces energy consumption and downtime costs caused by ineffective waiting and repetitive operations, resulting in higher production line cycle times and lower overall maintenance costs.

[0009] Preferably, the control unit is configured to perform the pressing and testing phases as follows: The hydraulic control unit presses the filter plates together until the oil pressure is greater than or equal to the first preset pressure; The test unit fills the filter chamber with medium and maintains the pressure after the pressure reaches the test pressure threshold. During the pressure holding period, monitor the pressure drop. If the drop is less than or equal to the pressure holding pressure drop threshold, the test is confirmed to be qualified; otherwise, an alarm is triggered and the process is locked.

[0010] By configuring the clamping and testing phases in this control unit such that the hydraulic unit clamps and the testing unit tests, and by adding a priority preemption strategy, the following technical effects can be achieved: First, establish a rigid prerequisite chain of "compression meets the standard - test the tightness meets the standard - only then can we proceed to the next stage", so that the reliability of the seal becomes a prerequisite for the advanced action, and avoid the risk of inducing material spraying, pollution and impact by starting the subsequent operation when the seal is poor. Second, by quantitatively monitoring the pressure drop during the pressure holding period, the traditional experience-based sealing judgment is transformed into a measurable and repeatable criterion, taking into account the adaptability under different filter cloth conditions, sealing surface wear and environmental fluctuations, which is conducive to improving batch-to-batch consistency and the objectivity of judgment. Third, once the test seal fails, an alarm is triggered and the process is locked, which can quickly prevent the risk from spreading to the feeding stage and subsequent stages, forming a closed loop of "early detection, early isolation, and early handling". This reduces rework and abnormal downtime, while providing maintenance personnel with clear clues for fault location (such as checking filter cloth, pressing surface, valve body and connecting parts), improving operation and maintenance efficiency and reducing the total life cycle cost.

[0011] Preferably, the control unit is configured to perform the feeding phase as follows: When the oil pressure is greater than or equal to the first preset pressure and the test is qualified, the feeding unit is started and feeding begins; During the feeding process, monitor the outlet pressure of the feeding unit. When the outlet pressure is lower than the backflow prevention pressure threshold, shut down the feeding unit and stop feeding.

[0012] By configuring the control unit to authorize the start of the feeding unit based on oil pressure and test tightness during the feeding stage, and using the outlet pressure of the feeding unit as the criterion for stopping the feeding process, the following technical effects can be achieved: First, the feeding action is strictly limited to the premise that the material has been compressed and sealed properly, so as to avoid applying material pressure to the filter chamber when the seal is unreliable or the compression is insufficient, which significantly reduces the risk of material spraying and leakage and ensures the safety of on-site personnel and equipment. Second, by tracking the outlet pressure in real time and setting the backflow prevention threshold, when the pipeline shows backflow, cavitation or abnormal pressure drop trend, the valve can be shut off and the pump can be stopped quickly to cut off the backflow channel and prevent material backflow from contaminating the upstream storage tank and upstream pipeline network. At the same time, it avoids mechanical impact and seal fatigue caused by water hammer and pressure fluctuations. Third, the combination of "dual access conditions + online reverse protection" is deployed in the feeding stage, which enables the stage to have both forward conditional authorization and rapid braking of reverse anomalies, comprehensively suppressing the chain problems caused by transient disturbances, valve position deviations or sudden changes in physical properties, and improving the stability, controllability and energy efficiency of the filtration process.

[0013] Preferably, the control unit is also configured to perform the feeding phase as follows: The filter chamber is determined to be full based on the change in mother liquor level and the feeding time. When the feeding time exceeds the maximum time threshold and the change in mother liquor level is less than or equal to the set threshold, the filter chamber is determined to be full and the feeding ends.

[0014] By configuring the control unit to superimpose the "change in mother liquor level - time" as a binary criterion for determining when the filter chamber is full and feeding ends during the feeding stage, the following technical effects can be achieved: First, the filtration endpoint is upgraded from the traditional "fixed duration" or "single pressure point" judgment to a composite criterion that combines time and liquid level change trends. This can still provide a more robust full chamber judgment when the material viscosity, solid content and filter cloth condition fluctuate, reducing the two-way deviation of "stopping before full" and "excessive tailing". Second, the threshold of liquid level change is linked to the time window, which can effectively filter out the influence of short-term noise and pipeline pressure disturbance on the in-situ determination, making the pump shutdown decision more robust, avoiding frequent start-up and shutdown due to transient fluctuations, and reducing energy consumption and motor thermal load. Third, by adaptively identifying the endpoint, the time of ineffective feeding can be shortened while ensuring filtration quality, reducing the redundant burden of subsequent extrusion and purging processes, improving single-cycle output and overall line cycle time, and providing data anchors for subsequent optimization modeling with "criteria-pump stop time" for operational data accumulation.

[0015] Preferably, the control unit is configured to monitor the extrusion liquid level during the extrusion phase and stop the extrusion phase when the extrusion liquid level is less than or equal to the extrusion liquid level threshold.

[0016] By configuring the control unit to control the extrusion process during the extrusion phase and using the extrusion liquid level as the criterion for stopping extrusion, the following technical effects can be achieved: First, the lower limit constraint based on liquid level can quickly terminate extrusion when there is insufficient extrusion medium, supply fluctuations, or abnormal suction, thus preventing the pump from dry running and running dry when there is no sufficient medium, thereby protecting the pump body, shaft seal, and bearings from damage caused by lack of lubrication and thermal shock. Second, the threshold shutdown strategy can reduce vibration and noise caused by cavitation and local vaporization in the pipeline, suppress valve core jamming and joint leakage caused by these factors, extend the service life of actuators and seals, and reduce maintenance costs caused by unexpected shutdowns. Third, after the extrusion stage is included in the measurement closed loop, the "media supply - extrusion effect - shutdown protection" can be connected into a traceable process link, which facilitates empirical regression and parameter tuning of extrusion strategies under different material batches and working conditions, making the subsequent extrusion time, pressure curve and liquid replenishment strategy more accurate, and improving the secondary dehydration efficiency and overall energy consumption performance.

[0017] Preferably, the control unit is configured during the purging phase to: control the purging unit to perform purging according to a preset timing sequence, monitor the purging pressure, and stop purging when the purging pressure exceeds the safe range.

[0018] By configuring the control unit to control the purging process during the purging phase and using the purging pressure as the criterion for stopping the purging, the following technical effects can be achieved: First, the time-sequential purging control ensures the orderly progress of gas path switching, valve opening and closing, and media flow, reducing gas path impact and filter chamber disturbance caused by disordered or overlapping actions. Secondly, setting a safe range for the purging pressure and implementing shutdown when the limit is exceeded can correct the situation in time when there are fluctuations in the gas source, valve jamming, or sudden changes in filter cake resistance. This avoids excessive pressure causing equipment and seal overload, and also avoids insufficient purging effect and energy waste due to excessively low pressure. Third, after the purging stage is incorporated into online pressure monitoring, the control system can appropriately optimize the purging duration and cycle time based on actual feedback within the safe range. This enables the system to suppress ineffective gas consumption while meeting drying / replacement targets, thereby reducing operating costs, noise and vibration, and providing traceable records and handling trajectories for subsequent maintenance, thus improving process consistency and audit visibility.

[0019] Preferably, the control unit is configured to: control the hydraulic unit to depressurize and monitor the oil pressure during the unloading phase; when the oil pressure is less than or equal to a second preset pressure, control the unloading unit to perform the unloading operation, which includes loosening the plate and unloading.

[0020] By configuring the control unit to control the pressure relief during the unloading stage and using oil pressure as the criterion for executing the unloading operation, the following technical effects can be achieved: First, by making "residual pressure confirmation" a mandatory entry condition for unloading, it can effectively prevent the plate from loosening when there is still dangerous energy in the hydraulic system, eliminate high-risk scenarios such as sudden movement of the plate and frame, pinching and splashing, and fundamentally safeguard the bottom line of personal and equipment safety. Second, the sequential link of pressure relief-confirmation-authorization provides clear safety boundaries and action sequence for the unloading process, reducing process interference caused by misjudgment or misoperation. At the same time, the load impact on valves, cylinders and pull plate mechanisms is more controllable, extending the service life of mechanical components. Third, by monitoring oil pressure in real time and authorizing thresholds, the control system can make consistent safety judgments under different oil temperatures, loads, and sealing conditions, avoiding the uncertainty caused by estimating "pressure relief completed" only by time, and recording relevant events for post-event review and continuous improvement, thereby enhancing the traceability and management compliance of the unloading process.

[0021] Preferably, the extrusion unit includes an extrusion pump and a level tank, the level tank being equipped with a level sensor.

[0022] By configuring a squeeze pump and a level tank within the squeeze unit and installing a level sensor for anti-dry-pump interlocking, the following technical effects can be achieved in this unit: First, the liquid level tank provides a stable buffer and reserve for the extrusion medium. Combined with the online measurement of the liquid level sensor, it can issue an early warning or trigger an interlock before the medium is insufficient or the supply fluctuates, preventing the extrusion pump from operating under the condition of insufficient medium and avoiding dry pumping, cavitation and the resulting heat accumulation damage from the source. Secondly, as a key detection point in the extrusion circuit, the liquid level sensor can form a closed-loop control with the pump's start-stop logic, enabling the extrusion process to have the self-protection capability of "supplying on demand and shutting down when exceeding limits", reducing the reliance on manual inspection and reducing frequent start-stop and energy waste caused by misjudgment. Third, standardizing the liquid level tank, liquid level sensor, and squeeze pump into a single functional unit helps to achieve modular installation and maintenance during engineering implementation, simplifies pipeline layout and fault location, improves system scalability and replaceability, provides a universal solution for equipment configuration of different scales and operating conditions, and thus reduces spare parts and maintenance costs throughout the entire life cycle.

[0023] In addition, the present invention also provides a safety control method for a plate and frame filter press, comprising the following steps: Compacting and sealing test steps: Compact the filter plate until the oil pressure is greater than or equal to the first preset pressure. After compaction, fill the filter chamber with medium until the pressure reaches the sealing test pressure threshold and maintain the pressure. If the pressure drop during the sealing period is less than or equal to the sealing pressure drop threshold, the sealing test is confirmed to be qualified. Feeding procedure: Start feeding when the oil pressure is greater than or equal to the first preset pressure and the test is qualified, and monitor the feeding pressure during the feeding process. Stop feeding when the feeding pressure is lower than the backflow prevention pressure threshold. Feeding endpoint determination steps: When the feeding time exceeds the maximum time threshold and the change in mother liquor level is less than or equal to the set threshold, the feeding ends; Extrusion steps: Start extrusion after feeding is completed, and stop extrusion when the extrusion liquid level is less than or equal to the extrusion liquid level threshold. Purging procedure: After extrusion, purge according to the preset sequence and monitor the purging pressure. Stop purging when the purging pressure exceeds the safe range. Unloading procedure: Start depressurization and monitor the oil pressure. When the oil pressure is less than or equal to the second preset pressure, perform the unloading operation.

[0024] By adopting the above technical solution, the steps of compaction and testing, feeding and endpoint determination, extrusion, purging and unloading are arranged with clear sequential relationships and condition judgments. The control principle of "the next step can only be entered when the preset conditions are met" runs through the entire process, constructing a step-by-step method with process status as the core. This achieves the procedural determination of the entry conditions, maintenance conditions and exit conditions of each key step at the execution level, enabling the control strategy to adapt to real-time changes and fluctuations in field signals, reducing reliance on manual experience or fixed time windows, and improving the repeatability and traceability of the method. It can monitor and threshold the process quantities such as feed pressure, mother liquor level change, extrusion level and purging pressure step by step during execution. Once a certain step exceeds the limit or fails to meet the conditions, it will immediately terminate or switch to a safe state to prevent the abnormality from spreading to subsequent steps. This methodology, which uses steps as the framework and conditions as the checkpoints, shifts the control behavior from "post-event correction" to "pre-event prevention," ensuring the stable progress of production and providing clear step boundaries and event timestamps for subsequent process optimization and data analysis. This significantly enhances the system's safety, robustness, and verifiability at the methodological level.

[0025] In addition, the present invention also provides a plate and frame filter press, including the above-mentioned plate and frame filter press safety control system.

[0026] By adopting the above technical solution, the safety control system of the plate and frame filter press is directly incorporated into the plate and frame filter press itself. This enables the equipment to inherently possess cross-stage interlocking and conditional control capabilities at the delivery level, avoiding uncertainties in signal interface, response timing, and safety chain integrity during retrofitting. It achieves coordinated optimization from structural design and signal layout to control execution, preserving the main process route of traditional plate and frame filter presses while introducing unified safety control logic at the system level. This ensures stable operation of the equipment even under complex media and variable operating conditions. It provides a consistent interface and human-machine interaction solution at the whole-machine level, facilitating installation, commissioning, parameter tuning, and maintenance. Simultaneously, it can interface with higher-level monitoring or production execution systems to form a closed loop of equipment-process-management. Therefore, the overall product achieves comprehensive improvements in inherent safety, operating efficiency, ease of use, and total life-cycle cost, making it more suitable for large-scale replication and long-term industrial application.

[0027] The beneficial effects of this invention are that by functionally coupling the control unit, hydraulic unit, testing unit, feeding unit, extrusion unit, purging unit, and unloading unit under the same control system, and triggering and constraining the process based on multiple signals, multi-stage interlocking control covering pressing and testing, feeding, extrusion, purging, and unloading is achieved. This significantly reduces the risks of material spraying, residual pressure misoperation, backflow impact, and abnormal dry running, and improves the safety, reliability, and maintainability of the entire process. Thus, it meets the requirements of providing fully automated safety interlocking control, ensuring good sealing, accurate determination of the feeding endpoint, prevention of backflow and dry pumping interlocking, and protection of residual pressure during unloading.

[0028] Furthermore, the design principle of this invention is reliable, the structure is simple, and it has a very wide range of application prospects.

[0029] Therefore, it is evident that the present invention has outstanding substantive features and significant progress compared with the prior art, and the beneficial effects of its implementation are also obvious. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of a safety control system for a plate and frame filter press provided by the present invention; Figure 2 This is a flowchart of a safety control method for a plate and frame filter press provided by the present invention.

[0032] The components include: 1. Control unit, 2. Hydraulic unit, 3. Testing unit, 4. Feeding unit, 5. Extrusion unit, 6. Purge unit, and 7. Discharge unit. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following embodiments are explanations of the present invention, but the present invention is not limited to the following implementation methods.

[0034] Example 1: like Figure 1 As shown in the figure, this embodiment provides a safety control system for a plate and frame filter press, including: Control unit 1 is used to receive pressure signals and liquid level signals and output control commands. The pressure signals include oil pressure. Hydraulic unit 2, connected to control unit 1, is used to apply clamping force to the filter plate and to perform pressure relief under the control of control unit 1; The sealing test unit 3 is connected to the control unit 1 and is used to fill the filter chamber with medium and perform sealing test after the filter plate is pressed. Feeding unit 4, connected to control unit 1, is used to feed materials into the filter chamber; The extrusion unit 5 is connected to the control unit 1 and is used to extrude and dehydrate the filter cake after feeding. The purging unit 6, connected to the control unit 1, is used to purge and dry the filter cake after extrusion. The unloading unit 7 is connected to the control unit 1 and is used to perform the unloading operation after the pressure is released; Control unit 1 is configured as follows: It receives detection signals from sensors in hydraulic unit 2, feeding unit 4, testing unit 3, extrusion unit 5, purging unit 6 and unloading unit 7; Determine whether the preset interlocking conditions are met based on the detection signal; Based on the judgment result, control commands are output to execute a multi-stage interlocking control process, which includes a pressing and testing stage, a feeding stage, a squeezing stage, a purging stage, and a discharging stage.

[0035] By adopting the above technical solution, the control unit 1, hydraulic unit 2, testing unit 3, feeding unit 4, extrusion unit 5, purging unit 6 and unloading unit 7 are functionally coupled under the same control system. The process is triggered and constrained based on multiple signals, realizing multi-stage interlocking control covering pressing and testing, feeding, extrusion, purging and unloading. This can significantly reduce the risks of material spraying, residual pressure misoperation, backflow impact, abnormal dry running, etc., and improve the safety, reliability and maintainability of the entire process. This meets the requirements of providing fully automated safety interlocking control, ensuring good sealing, accurate determination of feeding endpoint, prevention of backflow and dry pumping interlocking, and protection of residual pressure during unloading.

[0036] Specifically, control unit 1 triggers and constrains the process based on collected pressure signals (including oil pressure) and liquid level signals, constructing a multi-stage interlocking control system. This forms a closed-loop logic centered on "condition fulfillment—action authorization—status monitoring—abnormal interlocking," achieving conditional access for actions at each stage and sequential consistency across stages. This avoids false triggering and crosstalk caused by single-point timing, experience-based judgment, or local signal distortion, enabling the equipment to operate stably under different material viscosities, different filter cloth conditions, and different environmental disturbances. Moreover, it can uniformly identify and prioritize key signals within the same strategy framework, ensuring that actions involving personal and equipment safety are placed in a high-priority controlled state, and implementing flexible switching for non-critical links. This significantly reduces risks such as material spraying, residual pressure misoperation, backflow impact, and abnormal dry running, improving the safety, reliability, and maintainability of the entire process. At the same time, it reduces energy consumption and downtime costs caused by ineffective waiting and repetitive operations, resulting in higher production line cycle time and lower overall operation and maintenance costs.

[0037] Hereinafter, based on embodiments of this application, reference is made to... Figure 1 The schematic diagram shown provides a detailed explanation of the control unit 1, hydraulic unit 2, testing unit 3, feeding unit 4, extrusion unit 5, purging unit 6, and unloading unit 7 in the above system.

[0038] First, we will introduce the control unit 1, which is the core of the system, including its hardware composition, its connection relationship with other units, and its functional positioning.

[0039] Control unit 1, as the core of the system, is used to realize signal acquisition, logic judgment and execution control. Under the unified coordination of control unit 1, the hydraulic unit 2, the pressure testing unit 3 and other units execute rigorous multi-level pressure and state interlocking logic, thus forming a complete automated safety control system.

[0040] In terms of hardware configuration, in this embodiment, the control unit 1 preferably adopts a high-performance industrial-grade DCS controller (Distributed Control System), which has abundant I / O (Input / Output) modules and processing capabilities. It is internally configured with analog input (AI), digital input (DI), analog output (AO), and digital output (DO) modules to meet the needs of multi-source signal acquisition and multi-actuator drive.

[0041] The AI ​​module receives continuous signals from field instruments such as pressure sensors and level sensors; the DI module receives switching signals from limit switches, valve status feedback, and various sensors; the AO module outputs analog control signals to regulate hydraulic proportional valves and frequency converters; and the DO module outputs switching control signals to control the start and stop of electric valves, pneumatic valves, and pumps.

[0042] In terms of system connectivity, in this embodiment, the control unit 1 can be electrically connected to the hydraulic unit 2 to monitor the oil pressure of the hydraulic cylinder in real time and output control signals to achieve filter plate clamping or depressurization; connected to the test pressure unit 3 to monitor the test pressure and control the opening and closing of the air inlet valve and the pressure relief valve; connected to the feeding unit 4 to receive the feed pump outlet pressure and liquid level change signals and control the operation of the feed pump and the outlet valve; connected to the extrusion unit 5 to monitor the medium liquid level and control the start and stop of the extrusion pump; connected to the purging unit 6 to control the timing switch of the pneumatic valve and monitor the purging pressure; and connected to the unloading unit 7 to receive oil pressure feedback and issue the execution command for loosening or pulling the filter plate only after confirming safe depressurization.

[0043] In terms of software logic, the control unit 1 can preset multi-level pressure and status interlock control programs. This program is organized into a multi-stage control flow according to the process sequence of pressing and testing, feeding, extrusion, purging, and unloading. Through multi-condition judgment, priority preemption, and abnormal interlocking mechanisms, it ensures that the system meets safety access conditions at any stage. If the detection signal fails to meet the preset threshold or an abnormality occurs, the control unit 1 will immediately output a stop or lock command, and simultaneously display alarm information on the Human Machine Interface (HMI).

[0044] Meanwhile, control unit 1 is not only responsible for real-time process control, but also undertakes the function of acquiring and recording operational data. It can store curves of key parameters such as oil pressure, test pressure, feed pressure, mother liquor level, extrusion level, and purging pressure, and generate event logs when anomalies occur for subsequent fault analysis and maintenance management. This data traceability capability further enhances the reliability and maintainability of the system.

[0045] Through the design of the control unit 1 described above, the embodiments of this application realize centralized control and multi-level interlocking management of each execution unit, enabling the plate and frame filter press to safely operate in the entire process of pressing, testing, feeding, extrusion, purging and unloading in automated mode, significantly reducing the risks caused by operators relying on experience judgment, and improving the safety and stability of the overall system.

[0046] Next, each execution unit will be introduced and explained in a closed-loop description of "hardware + signal + logic". This includes its hardware composition, key sensors / actuators, and the interaction signals and logic control process with control unit 1. At the same time, while explaining the execution units, the multi-stage interlocking control process will be introduced.

[0047] Hydraulic unit 2 is the core actuator of this system for achieving filter plate clamping and depressurization. It applies clamping force to the filter plates under the command of control unit 1 and performs depressurization operation at the end of the process. In this embodiment, hydraulic unit 2 may include a hydraulic station, hydraulic cylinder, hydraulic pipeline, proportional regulating valve, and oil pressure sensor.

[0048] The hydraulic station provides constant-pressure high-pressure hydraulic oil to the hydraulic cylinders. The hydraulic cylinders directly act on the filter plates to press or release them. The opening of the proportional control valve is controlled by the analog signal output from the AO module in control unit 1. The proportional control valve controls the flow and pressure of the oil, achieving precise pressure increases and decreases, thus enabling stable pressing and controlled pressure release of the filter plates. The piston rod of the hydraulic cylinder is connected to the filter plate pressing mechanism. When control unit 1 issues a pressure increase (pressing) command, the opening of the proportional control valve gradually increases, hydraulic oil enters the cylinder and pushes the piston out, thereby pressing the filter plates. When control unit 1 issues a pressure release command, the opening of the proportional control valve gradually decreases, the proportional valve returns oil under control, the oil pressure gradually decreases, thereby releasing the filter plates. At the same time, the oil pressure sensor installed on the hydraulic cylinder or main pipeline is connected to the AI ​​module of control unit 1, and its signal is connected to the analog input port of control unit 1 to collect the oil pressure value in real time, serving as the basis for judging whether pressing or pressure release is complete. For example, in this embodiment of the application, the oil pressure value collected by this oil pressure sensor is recorded as follows: .

[0049] In this embodiment, the test pressure unit 3 can be installed on the filter chamber inlet pipe to detect the sealing performance of the filter plates after compression. It can include a gas source (nitrogen or compressed air), a pressure reducing valve, an inlet valve, a pressure relief valve, and a test pressure sensor. It is used to fill the filter chamber with a medium after the filter plates are compressed and to detect the sealing performance of the filter chamber. The gas source can be connected to the filter chamber via a pipeline. The inlet valve and pressure relief valve are both controlled by the DO module of the control unit 1. The pressure sensor is connected to the AI ​​module of the control unit 1 for real-time monitoring of the test pressure. Exemplarily, in this embodiment, the test pressure collected by the test pressure sensor is denoted as... .

[0050] In some embodiments of this application, the control unit 1 is configured to: The hydraulic control unit 2 presses the filter plate until the oil pressure is greater than or equal to the first preset pressure; The test unit 3 fills the filter chamber with medium and maintains the pressure after the pressure reaches the test pressure threshold. During the pressure holding period, monitor the pressure drop. If the drop is less than or equal to the pressure holding pressure drop threshold, the test is confirmed to be qualified; otherwise, an alarm is triggered and the process is locked.

[0051] Specifically, during the pressing stage, control unit 1 first sends a pressure increase command to hydraulic unit 2, the proportional regulating valve gradually opens, and the hydraulic cylinder pushes the filter plate inward to press it tight. Simultaneously, the oil pressure sensor on hydraulic unit 2 continuously collects oil pressure signals and transmits them to control unit 1. When the oil pressure value is greater than or equal to the first preset pressure... ,Right now When the filter plate is fully compressed, it is determined that the oil pressure has been reached; if the oil pressure does not reach the required level within the specified time... If the pressure is abnormal, control unit 1 will trigger an alarm indicating an abnormality in the pressing process and prevent the process from proceeding to the next stage. At this point, it is necessary to check the hydraulic station oil level, cylinder seals, or pipeline leaks. After further checks, the pressing stage can be restarted. This closed-loop control ensures that the filter plate will not enter the testing and feeding stages before it reaches sufficient sealing force.

[0052] When hydraulic unit 2 presses the filter plate to... Afterwards, control unit 1 automatically starts and enters the test pressure stage: control unit 1 first closes the pressure relief valve, then opens the air inlet valve to inject the air source medium into the filter chamber. At the same time, the test pressure sensor continuously collects the test pressure signal and feeds it back to control unit 1. The control center receives the test pressure signal and adjusts the test pressure accordingly. Reaching the test pressure threshold ,Right now The intake valve is then closed and maintained for a preset pressure holding time.

[0053] During the pressure holding period, control unit 1 calculates the test pressure. the drop value , if , the leak test is determined to be qualified; otherwise, if , the leak test is determined to be failed, an alarm is triggered, the process is locked, and automatic entry into the subsequent feeding stage is prohibited. Wherein, is a pressure holding drop threshold. Illustratively, the control unit 1 may set a "leak test completion flag" in its internal register. When the leak test is qualified, the flag is set to "true", and "leak test successful" is displayed on the HMI; otherwise, the "leak test completion flag" is set to "false", an audible and visual alarm of "leak test failed, please check the filter cloth and seal" is triggered on the HMI, and after inspection, manual confirmation and reset can be performed to re-enter the pressing and leak testing stage.

[0054] By configuring the control unit 1 to enable the hydraulic unit 2 to perform pressing and the leak testing unit 3 to perform leak testing during the pressing and leak testing stage, and adding a priority preemption strategy, the following technical effects can be achieved: First, a rigid precondition chain of "pressing qualification - leak testing qualification - entry into subsequent stages" is established. Through the cooperation of the hydraulic unit 2 and the leak testing unit 3, sealing reliability becomes a necessary condition for subsequent operations, so that dual safety conditions are established before the system starts feeding. That is, only when the filter plates are pressed to a pressure above the first preset pressure and the leak test is qualified can materials enter the filter chamber, which effectively avoids the risks of material spraying, pollution and impact caused by starting subsequent operations when the filter chamber is poorly sealed, and improves the safety and reliability of equipment operation; Second, through quantitative monitoring of the pressure drop during pressure holding, the traditional experience-dependent sealing judgment is converted into a measurable and repeatable criterion, which takes into account the adaptability under different filter cloth states, sealing surface wear and environmental fluctuations, and is conducive to improving the consistency between batches and the objectivity of judgment; Third, once the leak test is unqualified, an alarm is triggered and the process is locked, which can quickly prevent the risk from spreading to the feeding and subsequent stages, forming a closed loop of "early detection, early isolation and early treatment", reducing rework and abnormal shutdown time. Meanwhile, it provides maintenance personnel with clear fault location clues (such as checking the filter cloth, pressing surface, valve body and connecting components), improving operation and maintenance efficiency and reducing the full life cycle cost.

[0055] The feeding unit 4 is configured to deliver materials to the filter chamber after the filter plates are pressed and the leak test is completed. In the embodiment of the present application, the feeding unit 4 may include a feeding tank, a feeding pump, an outlet valve, and a pressure sensor and a liquid level gauge arranged at key positions of the pipeline.

[0056] The feed pump is preferably a variable frequency drive pump, whose start-up, shutdown, and speed are controlled by the DO / AO signals output by control unit 1. The outlet valve can be a pneumatic valve or an electric valve, and its opening and closing actions are also controlled by the DO / AO output signals of control unit 1. Two key pressure detection points are set on the outlet pipeline: one is a pressure sensor installed at the outlet of the feed pump to monitor the feed pressure; the other is a pressure sensor installed close to the filter chamber inlet, i.e., before the outlet valve and close to the filter press inlet, to monitor the backflow prevention conditions. The level gauge is installed in the mother liquor tank, and its continuous level signal is connected to control unit 1 to determine the feed endpoint. Exemplarily, in this embodiment, the outlet pressure collected by the pressure sensor at the feed pump outlet is recorded as... .

[0057] In some embodiments of this application, the control unit 1 is configured to: When the oil pressure is greater than or equal to the first preset pressure and the test is qualified, the feeding unit 4 is started and feeding begins; During the feeding process, monitor the outlet pressure of feeding unit 4. When the outlet pressure is lower than the anti-backflow pressure threshold, shut down feeding unit 4 and stop feeding.

[0058] Specifically, in terms of control logic, the start-up of the feeding unit 4 is subject to strict dual conditions, namely, it can only be started when the oil pressure of the hydraulic unit 2 is... Only when the test result of the sealing unit 3 is qualified will the control unit 1 issue a feeding start command to start the feeding pump and open the outlet valve. This ensures that the filter plate is compressed and the sealing is confirmed, thereby avoiding the occurrence of slurry spraying accidents caused by feeding material directly when the filter chamber is not closed or the seal is poor.

[0059] During the feeding process, the pressure sensor at the outlet of the feed pump continuously collects the outlet pressure of the feed unit 4. And transmit it to control unit 1 when outlet pressure is detected. Below the backflow prevention pressure threshold ,Right now If the backflow occurs, it indicates that there is a risk of backflow or sudden pressure drop in the pipeline. At this time, the control unit 1 will immediately trigger the anti-backflow interlock, output a pump stop command and other signals through the DO module, interlock to close the outlet valve and stop the feed pump, cut off the material backflow path, prevent the material from flowing back into the feed tank or pump body, and avoid equipment damage and process disorder.

[0060] By configuring the control unit 1 to authorize the start of the feeding unit 4 based on oil pressure and test tightness during the feeding stage, and using the outlet pressure of the feeding unit 4 as the criterion for stopping the feeding process, the following technical effects can be achieved: First, the feeding action is strictly limited to the premise that the material has been compressed and sealed properly, so as to avoid applying material pressure to the filter chamber when the seal is unreliable or the compression is insufficient, which significantly reduces the risk of material spraying and leakage and ensures the safety of on-site personnel and equipment. Second, by tracking the outlet pressure in real time and setting the backflow prevention threshold, when the pipeline shows backflow, cavitation or abnormal pressure drop trend, the valve can be shut off and the pump can be stopped quickly to cut off the backflow channel and prevent material backflow from contaminating the upstream storage tank and upstream pipeline network. At the same time, it avoids mechanical impact and seal fatigue caused by water hammer and pressure fluctuations. Third, the combination of "dual access conditions + online reverse protection" is deployed in the feeding stage, which enables the stage to have both forward conditional authorization and rapid braking of reverse anomalies, comprehensively suppressing the chain problems caused by transient disturbances, valve position deviations or sudden changes in physical properties, and improving the stability, controllability and energy efficiency of the filtration process.

[0061] Furthermore, control unit 1 is also configured to: The filter chamber is determined to be full based on the change in mother liquor level and the feeding time. When the feeding time exceeds the maximum time threshold and the change in mother liquor level is less than or equal to the set threshold, the filter chamber is determined to be full and feeding is stopped.

[0062] To accurately determine whether the filter chamber is full, control unit 1 uses a combined criterion of "time + liquid level change". Specifically, control unit 1 starts a timer at the same time as feeding begins, and the timer's duration is recorded as the feeding time. Meanwhile, the level gauge continuously collects the mother liquor tank level signal and transmits it to control unit 1, which then calculates the change in mother liquor level. When the feeding time Exceeding the maximum time threshold ,and Less than or equal to the set threshold ,Right now and When the filter chamber is determined to be basically full, the control unit 1 automatically stops the feed pump and closes the outlet valve, smoothly ending the feeding stage, thus avoiding stopping before full or over-filtration caused by simply relying on time or pressure judgment.

[0063] In some other embodiments of this application, it is also possible to... At that time, within a continuous period of time (e.g., 30 seconds), The establishment of the filter chamber is used as a standard to determine that it is basically full.

[0064] By configuring the control unit 1 to superimpose "mother liquor level change - time" as a binary criterion for stopping feeding when the filter chamber is full during the feeding stage, the following technical effects can be achieved: First, the filtration endpoint is upgraded from the traditional "fixed duration" or "single pressure point" judgment to a composite criterion that combines time and liquid level change trends. This can still provide a more robust full chamber judgment when the material viscosity, solid content and filter cloth condition fluctuate, reducing the two-way deviation of "stopping before full" and "excessive tailing". Second, the threshold of liquid level change is linked to the time window, which can effectively filter out the influence of short-term noise and pipeline pressure disturbance on the in-situ determination, making the pump shutdown decision more robust, avoiding frequent start-up and shutdown due to transient fluctuations, and reducing energy consumption and motor thermal load. Third, by adaptively identifying the endpoint, the time of ineffective feeding can be shortened while ensuring filtration quality, reducing the redundant burden of subsequent extrusion and purging processes, improving single-cycle output and overall line cycle time, and providing data anchors for subsequent optimization modeling with "criteria-pump stop time" for operational data accumulation.

[0065] Combining the two implementation methods of the feeding stage described above, and through the design and control logic of the feeding unit 4, this embodiment of the application forms three safety barriers during the feeding stage: firstly, the dual conditions of oil pressure and leak testing before feeding; secondly, the anti-backflow interlock of outlet pressure during the feeding process; and finally, the dual criteria of time and liquid level at the feeding endpoint. This multi-level interlocking strategy significantly improves the safety and reliability of the feeding stage, while also enhancing the accuracy of the feeding endpoint determination and reducing energy consumption and material waste.

[0066] The extrusion unit 5 is connected to the control unit 1 and is used to perform secondary extrusion dewatering on the filter cake after feeding is completed and the filter chamber is determined to be full, so as to further reduce the moisture content of the filter cake.

[0067] In some embodiments of this application, the extrusion unit 5 may include an extrusion pump, a level tank, and a level sensor disposed within the level tank. The extrusion pump may be a high-pressure water pump or other pump suitable for providing stable medium pressure, and its start-stop operation is controlled by the DO signal of the control unit 1. The level tank is used to store clean water or other dehydration media, and a level sensor is installed on it. Its continuous signal is connected to the AI / DI module of the control unit 1 for real-time detection of the liquid level. Exemplarily, in an embodiment of this application, the extruded liquid level collected by the level sensor on the level tank is recorded as... .

[0068] By configuring a compression pump and a liquid level tank within the compression unit 5, and by installing a liquid level sensor for anti-dry-pump interlocking, the following technical effects can be achieved: First, the liquid level tank provides a stable buffer and reserve for the extrusion medium. Combined with the online measurement of the liquid level sensor, it can issue an early warning or trigger an interlock before the medium is insufficient or the supply fluctuates, preventing the extrusion pump from operating under the condition of insufficient medium and avoiding dry pumping, cavitation and the resulting heat accumulation damage from the source. Secondly, as a key detection point in the extrusion circuit, the liquid level sensor can form a closed-loop control with the pump's start-stop logic, enabling the extrusion process to have the self-protection capability of "supplying on demand and shutting down when exceeding limits", reducing the reliance on manual inspection and reducing frequent start-stop and energy waste caused by misjudgment. Third, standardizing the liquid level tank, liquid level sensor, and squeeze pump into a single functional unit helps to achieve modular installation and maintenance during engineering implementation, simplifies pipeline layout and fault location, improves system scalability and replaceability, provides a universal solution for equipment configuration of different scales and operating conditions, and thus reduces spare parts and maintenance costs throughout the entire life cycle.

[0069] In some embodiments of this application, the control unit 1 is configured to monitor the extrusion liquid level during the extrusion phase and stop the extrusion phase when the extrusion liquid level is less than or equal to the extrusion liquid level threshold.

[0070] Specifically, in terms of control logic, after control unit 1 confirms the termination of feeding and closes the feed pump and outlet valve, it automatically issues a squeezing start command, starts the squeezing pump, and delivers the medium to the filter chamber for high-pressure squeezing of the filter cake. During the squeezing process, the liquid level sensor on the level tank continuously collects the squeezing liquid level. And transmit it to control unit 1, when the squeezing liquid level is detected. Less than or equal to the preset squeezing liquid level threshold ,Right now At this time, control unit 1 immediately triggers the anti-dry-running interlock and issues a pump stop command to stop the extrusion pump, thereby stopping the extrusion stage. For example, an alarm message "Extrusion liquid level insufficient" can be output on the HMI at the same time.

[0071] By configuring the control unit 1 during the extrusion stage to control the extrusion and use the extrusion liquid level as the criterion for stopping the extrusion, the following technical effects can be achieved: First, the lower limit constraint based on liquid level can quickly terminate extrusion when there is insufficient extrusion medium, supply fluctuations, or abnormal suction, thus preventing the pump from dry running and running dry when there is no sufficient medium, thereby protecting the pump body, shaft seal, and bearings from damage caused by lack of lubrication and thermal shock. Second, the threshold shutdown strategy can reduce vibration and noise caused by cavitation and local vaporization in the pipeline, suppress valve core jamming and joint leakage caused by these factors, extend the service life of actuators and seals, and reduce maintenance costs caused by unexpected shutdowns. Third, after the extrusion stage is included in the measurement closed loop, the "media supply - extrusion effect - shutdown protection" can be connected into a traceable process link, which makes it easier to perform empirical regression and parameter tuning of the extrusion strategy under different material batches and working conditions, making the subsequent extrusion time, pressure curve and liquid replenishment strategy more accurate, and improving the secondary dehydration efficiency and overall energy consumption performance. Fourth, the liquid level threshold can be flexibly adjusted according to the pump's minimum suction requirements and actual process needs to ensure that the pump always operates under safe conditions.

[0072] The purging unit 6 is connected to the control unit 1 and is used to purge and dry the filter cake after the extrusion stage, thereby further reducing the moisture content of the filter cake and improving its removability. In this embodiment, the purging unit 6 is similar to the test unit 3 and may include a gas source (such as compressed air or nitrogen), a pressure reducing valve, a pneumatic ball valve or solenoid valve, pipelines, and a purging pressure sensor located near the air inlet of the filter chamber. The gas source can be adjusted to a suitable working pressure by the pressure reducing valve and enter the filter chamber through the pneumatic valve to purge the filter cake. The opening and closing action of the valve is driven by the DO signal of the control unit 1, and the signal from the purging pressure sensor is connected to the AI ​​module of the control unit 1 to achieve real-time monitoring of the purging pressure. Exemplarily, in this embodiment, the purging pressure collected by this purging pressure sensor is denoted as... .

[0073] In some embodiments of this application, the control unit 1 is configured to: control the purging unit 6 to perform purging according to a preset timing sequence, monitor the purging pressure, and stop purging when the purging pressure exceeds the safe range.

[0074] Specifically, in terms of control logic, after the extrusion stage is completed, control unit 1 automatically enters the purging stage: First, according to the preset timing logic, control unit 1 sequentially opens or closes the pneumatic valves to deliver gas into the filter chamber in batches or continuously, thereby achieving staged purging of the filter cake. Through reasonable timing control, gas consumption can be reduced and energy efficiency improved while ensuring the purging effect.

[0075] During the purging process, the purging pressure sensor continuously collects the purging pressure. And determine its upper and lower limits. When the purging pressure Within the set safety range, i.e. The purging operation continues until the purging pressure exceeds the safe range. or Upon this, control unit 1 immediately issues a stop command, closes the pneumatic valve, and stops purging. and These are the minimum and maximum purge pressure thresholds within the set safety range, respectively. For example, an audible and visual alarm can be triggered simultaneously to indicate an anomaly. This logic effectively prevents equipment damage due to excessive pressure or insufficient purge due to insufficient pressure.

[0076] By configuring the control unit 1 during the purging phase to control the purging and using the purging pressure as the criterion for stopping the purging, the following technical effects can be achieved: First, the time-sequential purging control ensures the orderly advancement of gas path switching, valve opening and closing, and media flow, reducing gas path impact and filter chamber disturbance caused by disordered or overlapping actions, and can efficiently complete the gas purging and drying of the filter cake. Second, under the management of control unit 1, the safe range of the purging pressure is set and the machine is shut down if the limit is exceeded. It has a safety interlock function for purging pressure, which can correct the deviation in time when the gas source fluctuates, the valve is stuck or the filter cake resistance changes suddenly, so as to avoid the equipment and seal being overloaded due to excessive pressure, and also to avoid insufficient purging effect and energy waste due to excessively low pressure, thereby ensuring the safety and stability of the entire purging process. Third, after the purging stage is incorporated into online pressure monitoring, the control system can appropriately optimize the purging duration and cycle time based on actual feedback within the safe range. This enables the system to suppress ineffective gas consumption while meeting drying / replacement targets, thereby reducing operating costs, noise and vibration, and providing traceable records and handling trajectories for subsequent maintenance, thus improving process consistency and audit visibility.

[0077] The unloading unit 7 is connected to the control unit 1 and is used to perform filter cake unloading operations after the hydraulic system is depressurized. In this embodiment, the unloading unit 7 may include a plate pulling mechanism, a plate loosening mechanism, an unloading trolley, a drive motor, and position limit switches. The plate pulling mechanism is used to separate the filter plates piece by piece or in groups, allowing the filter cake to fall off naturally; the plate loosening mechanism releases the compressed state of the filter plates through a mechanical unlocking action before unloading; the unloading trolley is used to receive or transfer the filter cake; the drive motor and corresponding actuators are controlled by the DO output of the control unit 1, while the limit switch and position sensor signals are returned to the DI input of the control unit 1 to provide feedback on the operation status of the unloading mechanism.

[0078] In some embodiments of this application, the control unit 1 is configured to: control the hydraulic unit 2 to depressurize and monitor the oil pressure during the unloading phase; and control the unloading unit 7 to perform the unloading operation when the oil pressure is less than or equal to a second preset pressure. The unloading operation includes loosening the plate and unloading.

[0079] Specifically, in terms of control logic, control unit 1 first sends a pressure relief command to hydraulic unit 2, controlling the proportional regulating valve to gradually return oil, so that the hydraulic pressure decreases smoothly. At the same time, hydraulic unit 2 continuously collects oil pressure signals and transmits them to control unit 1, thereby monitoring the oil pressure in real time. When a specific oil pressure value is detected... Less than or equal to the second preset pressure ,Right now When the hydraulic unit 2 has completed safe depressurization, control unit 1 will only allow the unloading unit 7 to start; if the oil pressure... Still higher ,Right now When this happens, the unloading action is locked. For example, when the unloading action is locked, a prompt message "Unloading is prohibited, hydraulic pressure is not fully released" can be output to the HMI interface.

[0080] It should be noted that, since hydraulic pressure values ​​also need to be collected and compared during the unloading stage, and the hydraulic pressure signals collected during both the unloading and compaction / testing stages come from the hydraulic pressure sensor on hydraulic unit 2, to distinguish between the different stages, the hydraulic pressure value collected during the unloading stage is recorded as follows: .

[0081] After confirming the hydraulic pressure is safe, control unit 1 sends a start signal to drive unloading unit 7 to perform unloading operations, including loosening the filter plates and unloading. The loosening action gradually releases the filter plates, and then the plate-pulling mechanism, driven by a motor, sequentially pulls open the filter plates. The filter cake falls from the filter chamber into the unloading trolley or collection device by its own weight or slight vibration. Throughout the process, control unit 1 collects signals from limit switches and position sensors in real time to ensure the plate-pulling actions are completed in sequence. If jamming or misalignment is detected, the machine can be stopped immediately and an alarm can be triggered to prevent equipment damage.

[0082] By configuring the control unit 1 to control the pressure relief during the unloading stage and using the oil pressure as the criterion for executing the unloading operation, the following technical effects can be achieved: First, by making "residual pressure confirmation" a mandatory entry condition for unloading, the release of the plate can be effectively prevented when there is still dangerous energy in the hydraulic system, eliminating high-risk scenarios such as sudden movement of the plate frame, pinching and splashing, fundamentally eliminating the danger of releasing the plate under pressure, and thus safeguarding the bottom line of personal and equipment safety. Second, the sequential link of "pressure relief-confirmation-authorization" gives the unloading process clear safety boundaries and action sequence, reduces process interference caused by misjudgment or misoperation, and makes the load impact on valves, cylinders and pull plate mechanisms more controllable, extending the service life of mechanical components. Third, by monitoring oil pressure in real time and authorizing thresholds, the control system can make consistent safety judgments under different oil temperatures, loads and sealing conditions, avoiding the uncertainty caused by estimating "pressure relief completed" only by time, and recording relevant events for post-event review and continuous improvement, thereby enhancing the traceability and management compliance of the unloading process. Fourth, the unloading unit 7, as the last link in the fully automated process, forms a closed loop with the pressure relief control of the hydraulic unit 2, constituting a complete multi-level pressure interlocking system.

[0083] In some other embodiments of this application, to ensure that the system can respond quickly and maintain safe operation under complex working conditions, the control unit 1 may have a preset logical priority mechanism. This priority logic is used to hierarchically manage different types of interlocking conditions and abnormal events, and to determine the order and preemption of actions to be executed according to the priority.

[0084] Specifically, interlocking conditions directly related to personal safety and equipment safety are given the highest priority. For example, when hydraulic pressure is detected... When the system immediately confirms that the unloading process can begin, but if the hydraulic oil pressure is still higher than P2, control unit 1 prohibits any unloading action; in addition, when the outlet pressure of the feeding unit 4 is lower than the set anti-backflow pressure threshold ( ), or when the extrusion liquid level is below the extrusion liquid level threshold ( When this occurs, control unit 1 will also trigger the pump stop and valve closure action with the highest priority to prevent equipment damage caused by backflow and dry pumping. Once the above-mentioned safety relief and equipment protection interlocks are triggered, they will be executed immediately and will not be affected by other process steps.

[0085] For abnormal situations related to process integrity, control unit 1 is assigned a higher priority. For example, during the compaction and sealing test stages, if the sealing test result is deemed unqualified, control unit 1 immediately interrupts the process and triggers an alarm, preventing entry into the feeding stage. This priority setting ensures that the system will not enter the material feeding step if the sealing performance is not up to standard, thus preventing slurry spraying accidents from occurring at the source.

[0086] In contrast, normal process switching and time-based decision-making logic have lower priority and are executed sequentially without triggering high-priority interlocks. Through this hierarchical design, control unit 1 further constructs a well-defined and responsive priority control system based on multi-level pressure and status interlocks, ensuring that the system can prioritize the execution of the most critical safety actions under any abnormal circumstances.

[0087] In summary, the safety control system for a plate and frame filter press provided in this application integrates hardware and software through a control unit 1 to coordinate the hydraulic unit 2, the testing unit 3, the feeding unit 4, the extrusion unit 5, the purging unit 6, and the unloading unit 7. This integrates the originally scattered, manual-judgment-dependent operation steps into a fully automated, highly safe process, achieving automation and safety throughout the entire process. During the pressing and testing stages, the system confirms sealing performance through oil pressure judgment and pressure drop during the holding pressure stage. During the feeding stage, oil pressure and testing results serve as entry conditions, and a composite criterion of anti-backflow and feeding endpoint is set. During the extrusion and purging stages, extrusion liquid level and purging pressure monitoring are introduced to achieve anti-dry pumping and pressure over-limit protection. During the unloading stage, the oil pressure is ≤ a second preset pressure to ensure that the unloading operation is carried out under conditions of no residual pressure. Through the above-mentioned multi-level pressure and state interlocking logic, the system effectively avoids risks such as spraying, backflow, dry pumping, and pressurized unloading, significantly improving the safety, reliability, and automation level of equipment operation.

[0088] Example 2: like Figure 2 As shown in the figure, this embodiment provides a safety control method for a plate and frame filter press, which includes the following steps: Step S1: Compressing and sealing test: Compress the filter plate until the oil pressure is greater than or equal to the first preset pressure. After the compression is completed, fill the filter chamber with medium until the pressure reaches the sealing test pressure threshold and hold the pressure. If the pressure drop during the holding period is less than or equal to the holding pressure drop threshold, the sealing test is confirmed to be qualified. Step S2: Feeding Step: Start feeding when the oil pressure is greater than or equal to the first preset pressure and the test is qualified. Monitor the feeding pressure during the feeding process. Stop feeding when the feeding pressure is lower than the anti-backflow pressure threshold. Step S3: Feeding endpoint determination step: When the feeding time exceeds the maximum time threshold and the change in mother liquor level is less than or equal to the set threshold, the feeding ends; Step S4: Extrusion step: Start extrusion after feeding is completed, and stop extrusion when the extrusion liquid level is less than or equal to the extrusion liquid level threshold. Step S5: Purging step: After extrusion, purge according to the preset sequence and monitor the purging pressure. When the purging pressure exceeds the safe range, stop purging. Step S6: Unloading Step: Start depressurization and monitor the oil pressure. When the oil pressure is less than or equal to the second preset pressure, perform the unloading operation.

[0089] By adopting the above technical solution, the steps of compaction and testing, feeding and endpoint determination, extrusion, purging and unloading are arranged with clear sequential relationships and condition judgments. The control principle of "the next step can only be entered when the preset conditions are met" runs through the entire process, constructing a step-by-step method with process status as the core. This achieves the procedural determination of the entry conditions, maintenance conditions and exit conditions of each key step at the execution level, enabling the control strategy to adapt to real-time changes and fluctuations in field signals, reducing reliance on manual experience or fixed time windows, and improving the repeatability and traceability of the method. It can monitor and threshold the process quantities such as feed pressure, mother liquor level change, extrusion level and purging pressure step by step during execution. Once a certain step exceeds the limit or fails to meet the conditions, it will immediately terminate or switch to a safe state to prevent the abnormality from spreading to subsequent steps. This methodology, which uses steps as the framework and conditions as the checkpoints, shifts the control behavior from "post-event correction" to "pre-event prevention," ensuring the stable progress of production and providing clear step boundaries and event timestamps for subsequent process optimization and data analysis. This significantly enhances the system's safety, robustness, and verifiability at the methodological level.

[0090] Hereinafter, based on embodiments of this application, reference is made to... Figure 2 The flowchart shown illustrates steps S1 to S6 of the above method.

[0091] In step S1, the filter plate is first pressed, and the oil pressure signal during the process is collected. When the collected oil pressure value... Greater than or equal to the first preset pressure At that time, the compaction is considered complete.

[0092] Subsequently, the pressure test procedure is initiated, and the gas source medium is filled into the filter chamber until the pressure reaches a certain level. Reaching the test pressure threshold At this point, the gas supply medium is stopped, and the pressure holding stage begins.

[0093] During the pressure holding period, the test pressure is continuously monitored. Change If the pressure drops during the pressure holding period Less than or equal to the holding pressure drop threshold If the password test is successful, the password test is confirmed to be successful; otherwise, the password test is deemed to have failed, an alarm is immediately triggered, the process is locked, and entry into step S2 is prohibited.

[0094] In step S2, when the oil pressure When the test is qualified, the feeding command is issued to start feeding and allow the material to enter the filter chamber.

[0095] During the feeding process, the feed pressure is continuously collected. When the feed pressure Below the backflow prevention pressure threshold If this occurs, immediately interlock to stop feeding and cut off the return path to prevent material backflow and equipment damage.

[0096] In step S3, a timer is started simultaneously with the commencement of feeding, and the liquid level change in the mother liquor tank is monitored in real time. When the feeding time... Exceeding the maximum time threshold And the change in mother liquor level Less than or equal to the set threshold during the continuous monitoring period When the filter chamber is determined to be basically full, the feeding is automatically stopped, and the feeding process is smoothly completed, avoiding the filter chamber not being full due to stopping the pump too early, or the energy consumption and material waste caused by stopping the pump too late.

[0097] In step S4, after feeding is terminated, extrusion is initiated to inject extrusion medium into the filter chamber for dewatering the filter cake. Simultaneously, the liquid level signal of the extrusion tank is acquired in real time; when the extrusion liquid level is detected... Less than or equal to the squeeze liquid level threshold If the pump runs dry, the anti-dry-running interlock is immediately triggered, stopping the extrusion and triggering an alarm indicating "insufficient extrusion liquid level." This logic prevents the extrusion pump from running dry in a low-liquid state, protecting the equipment.

[0098] In step S5, after extrusion, the purging process begins. Pneumatic valves are opened and closed sequentially according to a preset time sequence, delivering compressed air or nitrogen into the filter chamber in stages to purge the filter cake and further reduce its moisture content. During the purging process, the purging pressure is continuously monitored. When the purging pressure is detected to exceed the preset safety range (such as exceeding the upper limit or falling below the lower limit), purging will immediately stop and an alarm will be triggered. This interlock effectively prevents insufficient purging or equipment damage caused by abnormal pressure.

[0099] In step S6, after purging is completed, a pressure relief operation is performed to gradually reduce the system oil pressure. During this process, oil pressure signals are acquired in real time. Only when oil pressure Less than or equal to the second preset pressure Only when the time is right will the unloading operation be authorized, including the loosening and pulling of the plate, and the filter cake will fall into the unloading device under gravity or vibration; if the hydraulic pressure is high... Still higher If the pressure is not released, unloading is prohibited, and a message will be displayed stating "Unloading is prohibited if hydraulic pressure is not released" to avoid the danger of the pressurized plate being loosened.

[0100] In summary, the safety control method for a plate and frame filter press provided in this application introduces multiple parameters such as oil pressure, test pressure, outlet pressure, mother liquor level, and purging pressure throughout the entire process, including pressing and testing, feeding, extrusion, purging, and unloading, achieving multi-stage automated safety interlock control. This method not only effectively prevents feeding failures due to unqualified test results, backflow during feeding, and dry pumping during extrusion, but also promptly interrupts the process when purging pressure is abnormal or hydraulic pressure is not fully released, thereby avoiding safety risks such as slurry spraying, equipment damage, and pressurized unloading. Compared with existing control methods that rely on timing or experience-based judgment, this method significantly improves safety, reliability, and operational efficiency.

[0101] Example 3: This embodiment provides a plate and frame filter press, including the plate and frame filter press safety control system of any of the above embodiments.

[0102] The plate and frame filter press is structurally composed of conventional components such as a frame, filter plate assembly, hydraulic mechanism, filter cloth, and unloading device. Its control section integrates the plate and frame filter press safety control system provided in this application. By applying this safety control system to the entire machine, the plate and frame filter press in this embodiment can achieve automated operation throughout the entire process of pressing, testing, feeding, extrusion, purging, and unloading, and introduces multi-level pressure and status interlocking conditions at each key step. Compared with traditional equipment relying on manual experience or simple timed control, this plate and frame filter press has higher safety, reliability, and automation levels, effectively avoiding risks such as slurry spraying, backflow, dry pumping, and pressurized unloading, thereby significantly improving the equipment's service life and production efficiency.

[0103] The above-disclosed embodiments are merely preferred embodiments of the present invention, but the present invention is not limited thereto. Any non-creative variations that can be conceived by those skilled in the art, as well as any improvements and modifications made without departing from the principles of the present invention, should fall within the protection scope of the present invention.

Claims

1. A safety control system for a plate and frame filter press, characterized in that, include: A control unit is used to receive pressure signals and liquid level signals and output control commands, wherein the pressure signals include oil pressure; A hydraulic unit, connected to the control unit, is used to apply a clamping force to the filter plate and to perform pressure relief under the control of the control unit; A sealing test unit, connected to the control unit, is used to fill the filter chamber with medium and perform a sealing test after the filter plate is pressed. A feeding unit, connected to the control unit, is used to feed materials into the filter chamber; The extrusion unit, connected to the control unit, is used to extrude and dehydrate the filter cake after feeding is completed; A purging unit, connected to the control unit, is used to purge and dry the filter cake after extrusion; The unloading unit, connected to the control unit, is used to perform the unloading operation after the pressure relief is completed; The control unit is configured as follows: Receive detection signals from sensors in the hydraulic unit, the feeding unit, the testing unit, the extrusion unit, the purging unit, and the unloading unit; Determine whether the preset interlocking conditions are met based on the detection signal; The control command is output based on the judgment result to execute the multi-stage interlocking control process, which includes the pressing and testing stage, the feeding stage, the extrusion stage, the purging stage, and the unloading stage. The control unit is configured to perform the pressing and testing phase as follows: The hydraulic unit is controlled to press the filter plate until the oil pressure is greater than or equal to the first preset pressure; The test unit is controlled to fill the filter chamber with medium and maintain the pressure after the pressure reaches the test pressure threshold. During the pressure holding period, the pressure drop is monitored. If the drop is less than or equal to the pressure holding pressure drop threshold, the test is confirmed to be qualified; otherwise, an alarm is triggered and the process is locked. The control unit is configured to perform the feeding phase as follows: When the oil pressure is greater than or equal to the first preset pressure and the test is qualified, the feeding unit is started and feeding begins; During the feeding process, the outlet pressure of the feeding unit is monitored. When the outlet pressure is lower than the anti-backflow pressure threshold, the feeding unit is shut down and the feeding is stopped. The control unit is also configured to perform the feeding phase as follows: The filter chamber is determined to be full based on the change in mother liquor level and the feeding time. When the feeding time exceeds the maximum time threshold and the change in mother liquor level is less than or equal to the set threshold, the filter chamber is determined to be full and the feeding ends.

2. The safety control system for a plate and frame filter press as described in claim 1, characterized in that, The control unit is configured to monitor the extrusion liquid level during the extrusion phase and stop the extrusion phase when the extrusion liquid level is less than or equal to the extrusion liquid level threshold.

3. The safety control system for a plate and frame filter press as described in claim 1, characterized in that, The control unit is configured to: control the purging unit to perform purging according to a preset timing sequence, monitor the purging pressure, and stop the purging when the purging pressure exceeds the safe range.

4. The safety control system for a plate and frame filter press as described in claim 1, characterized in that, The control unit is configured to: control the hydraulic unit to depressurize and monitor the oil pressure when the oil pressure is less than or equal to a second preset pressure, and control the unloading unit to perform the unloading operation, which includes loosening the plate and unloading.

5. The safety control system for a plate and frame filter press as described in claim 1, characterized in that, The extrusion unit includes an extrusion pump and a liquid level tank, and the liquid level tank is equipped with a liquid level sensor.

6. A safety control method for a plate and frame filter press, implemented using the plate and frame filter press safety control system as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Compacting and sealing test steps: Compact the filter plate until the oil pressure is greater than or equal to the first preset pressure. After the compaction is completed, fill the filter chamber with medium until the pressure reaches the sealing test pressure threshold and maintain the pressure. If the pressure drop during the holding period is less than or equal to the holding pressure drop threshold, the sealing test is confirmed to be qualified. Feeding procedure: Feeding is started when the oil pressure is greater than or equal to the first preset pressure and the test is qualified. During the feeding process, the outlet pressure of the feed is monitored. When the outlet pressure is lower than the anti-backflow pressure threshold, the feeding is stopped. Feeding endpoint determination step: When the feeding time exceeds the maximum time threshold and the change in mother liquor level is less than or equal to the set threshold, the feeding is terminated; Extrusion step: After the feeding is completed, extrusion is started. When the extrusion liquid level is less than or equal to the extrusion liquid level threshold, the extrusion is stopped. Purging step: After the extrusion is completed, purging is performed in a preset sequence, and the purging pressure is monitored. When the purging pressure exceeds the safe range, the purging is stopped. Unloading procedure: Start depressurization and monitor the oil pressure. When the oil pressure is less than or equal to the second preset pressure, perform the unloading operation.

7. A plate and frame filter press, characterized in that, Includes a plate and frame filter press safety control system as described in any one of claims 1-5.

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