A method, system and medium for controlling the moisture content of a cake of a diaphragm filter

Abstract

The application discloses a kind of diaphragm filter press mud cake moisture content control method, system and medium, belong to solid-liquid separation technical field.Method includes: in feed stage, by online concentration meter and flowmeter real-time integral calculation entering filter room total mass of absolute dry solid;Based on filter room total volume and preset target moisture content, using material balance principle, the target injection volume of press water required to reach target moisture content is calculated;In the pressing stage, the actual injection volume of press water is monitored in real time, and the pressing is automatically stopped when the actual injection volume reaches the target value.The moisture content control that cannot be directly measured is converted into the press water volume control that can be accurately measured, the closed-loop control of reaching standard is realized, and the over-pressing phenomenon is completely eliminated, while ensuring the accurate standard of mud cake moisture content, significantly shortening the pressing cycle, reducing energy consumption, prolonging the service life of equipment, suitable for municipal sludge, industrial solid waste and other materials deep dewatering treatment.

Description

Technical Field

[0001] This invention relates to the field of solid-liquid separation technology, and in particular to a method, system and medium for controlling the moisture content of filter cake in a diaphragm filter press. Background Technology

[0002] Diaphragm filter presses are core equipment for the deep dewatering of materials such as sludge and minerals. Their operation mainly includes two key stages: feed filtration and diaphragm pressing. In the feed filtration stage, the material is pumped into the filter chamber composed of filter plates. Liquid passes through the filter cloth and is discharged, while solid particles are retained to form an initial filter cake. Subsequently, in the diaphragm pressing stage, high-pressure water or gas is injected into the diaphragm chamber, causing the diaphragm to expand and squeeze the filter cake, further removing moisture from the cake.

[0003] Currently, the industry generally adopts a "post-production testing" model to control the moisture content of filter cake after pressing. This means that after pressing and unloading, the produced filter cake is sampled and tested to determine whether the moisture content meets the contract or process requirements (e.g., moisture content ≤ 50%). This model has significant drawbacks: First, the test results lag far behind the production process. Once the moisture content is found to be substandard, the entire batch of material has already been processed, making online correction impossible. This may lead to penalties for breach of contract or the need for the material to be returned for reprocessing, resulting in economic losses and process disruptions. Second, to avoid substandard moisture content, operators often tend to extend the pressing time or increase the pressing pressure to ensure that the "filter cake is dry enough." This "over-pressing" state not only wastes energy and reduces equipment processing efficiency but also exacerbates the fatigue and wear of core components such as diaphragms and filter cloths, shortening their service life.

[0004] Furthermore, the termination of existing pressing processes typically relies on the subjective judgment of operators or fixed timing controls, which cannot adapt to fluctuations in parameters such as the concentration and composition of the feed sludge. When the feed concentration fluctuates, the same pressing time and pressure often result in inconsistent moisture content in the sludge cake, leading to poor product uniformity and making it difficult to meet the stable requirements for sludge cake drying in subsequent disposal processes (such as incineration, landfill, and building material utilization). Therefore, there is an urgent need for a technology that can predict and actively control the final sludge cake moisture content in real time during the pressing process to achieve precise, efficient, and energy-saving dewatering process control. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that existing diaphragm filter presses rely on post-process testing and experience control, which cannot predict and accurately control the moisture content of the filter cake in real time during the pressing process, resulting in problems of lag and over-pressing.

[0006] In a first aspect, embodiments of the present invention provide a method for controlling the moisture content of filter cake in a diaphragm filter press, wherein a controller performs the following steps: During the feeding stage, the feed sludge concentration C monitored by the online sludge concentration meter and the feed sludge instantaneous flow rate dV monitored by the first electromagnetic flow meter are acquired in real time, and the total dry solid mass M_dry entering the filter chamber of the filter press is calculated and determined in real time according to the formula M_dry=∫(C×dV). Before pressing begins, the target pressing water injection volume V_squeeze_target required to achieve the target moisture content is calculated based on the material balance principle, according to the preset final target moisture content ω_target, the total mass of the oven-dry solids M_dry, and the total fixed volume V_total of the filter chamber of the filter press. During the pressing stage, the pressing pump is started to inject pressing water into the diaphragm chamber, and the actual injection volume V_squeeze_current of the pressing water is monitored in real time using the second electromagnetic flow meter. During the pressing process, the actual injection volume V_squeeze_current is compared with the target pressed water injection volume V_squeeze_target. When V_squeeze_current ≥ V_squeeze_target, the pressing process is stopped.

[0007] Secondly, embodiments of the present invention also provide a diaphragm filter press cake moisture content control system, characterized in that it includes: The main body of the diaphragm filter press has filter chambers with a fixed total volume V_total; The feed pipeline is equipped with an online sludge concentration meter and a first electromagnetic flow meter; The pressing water pipeline is equipped with a second electromagnetic flow meter and a pressing pump; The controller is electrically connected to the online sludge concentration meter, the first electromagnetic flow meter, the second electromagnetic flow meter, and the press pump, respectively. The controller is configured to perform the steps of the method described above.

[0008] Thirdly, embodiments of the present invention also provide a storage medium, characterized in that the storage medium stores a computer program, which, when executed by a processor, can implement the steps of the method described above.

[0009] This invention utilizes a combination of a concentration meter and a flow meter during the feeding stage to acquire the key baseline data—the absolute dry solids mass entering the system—in real time. Based on the fixed volume of the filter chamber and the target moisture content, the required volume of pressing water is pre-calculated, transforming the intangible problem of moisture content control into the directly measurable and controllable problem of pressing water volume control, thus achieving a clever shift in control dimensions. During the pressing stage, the real-time accumulated pressing water volume serves as the endpoint criterion, automatically stopping when the target value is reached, achieving precise control by stopping only when the target is met. Therefore, this technical solution ensures that the moisture content of the mud cake precisely meets the standard before unloading, completely eliminating the commercial and compliance risks caused by unqualified moisture content. Simultaneously, by avoiding the over-pressing operation adopted in traditional methods for safety, it significantly shortens the pressing cycle, reduces water and electricity consumption, and reduces fatigue wear of core components. While ensuring stable and uniform mud cake quality after dewatering, it achieves high efficiency, energy saving, and intelligent operation of the dewatering process. Attached Figure Description

[0010] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 A schematic flowchart of the method for controlling the moisture content of filter cake in a diaphragm filter press provided in an embodiment of the present invention; Figure 2 A schematic diagram illustrating the principle of the method for controlling the moisture content of filter cake in a diaphragm filter press according to an embodiment of the present invention; Figure 3 A schematic diagram of the diaphragm filter press cake moisture content control system provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the diaphragm filter plate provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the filter press chamber state after feeding is completed, provided in an embodiment of the present invention. Figure 6 This is a schematic diagram of the diaphragm cavity state provided in an embodiment of the present invention.

[0012] Among them, 1-sludge storage tank; 2-sludge feed pump; 3-controller; 4-online sludge concentration meter; 5-first electromagnetic flow meter; 6-feed pressure transmitter; 7-feed pipeline; 8-filtrate discharge pipeline; 9-diaphragm filter press body; 10-pressing pressure transmitter; 11-pressing pipeline; 12-pressing water return pneumatic valve; 13-second electromagnetic flow meter; 14-pressing water return pipeline; 15-pressing pump; 16-pressing water tank; 17-diaphragm filter plate; 171-diaphragm base plate; 172-diaphragm sheet; 18-diaphragm cavity; 19-filter chamber. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0015] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0016] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0017] As used in this specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [described condition or event] is detected," or "in response to detection of [described condition or event]."

[0018] like Figures 1-6As shown, this embodiment of the invention provides a method for controlling the moisture content of filter cake in a diaphragm filter press, wherein the controller executes the following steps: S1. During the feeding stage, the feed sludge concentration C monitored by the online sludge concentration meter 4 and the feed sludge instantaneous flow rate dV monitored by the first electromagnetic flow meter 5 are acquired in real time, and the total dry solids mass M_dry entering the filter chamber of the filter press is calculated and determined in real time according to the formula M_dry=∫(C×dV).

[0019] In this step, controller 3 issues a control command to start sludge feed pump 2, which transports sludge from sludge storage tank 1 through feed pipeline 7 into the diaphragm filter press body 9. During the feeding process, online sludge concentration meter 4 and first electromagnetic flow meter 5 installed on feed pipeline 7 monitor the concentration C (unit: kg / m³) of the fed sludge in real time. 3 The controller 3 reads the signals monitored by the online sludge concentration meter 4 and the first electromagnetic flow meter 5 in real time, and calculates the total mass of oven-dry solids entering all filter chambers by integrating the data using the formula M_dry = ∫(C × dV). When the feed pressure monitored by the feed pressure transmitter 6 reaches the set value or the feeding time ends, the feeding process stops, and the total oven-dry solids mass M_dry for that batch is obtained. This step obtains this crucial baseline data of oven-dry solids mass through real-time measurement, laying the foundation for material balance in subsequent precise control and eliminating the impact of feed concentration fluctuations on control accuracy.

[0020] S2. Before pressing begins, based on the preset final target moisture content of the mud cake ω_target, the total mass of the oven-dry solids M_dry, and the total fixed volume of the filter chamber of the filter press V_total, the target pressing water injection volume V_squeeze_target required to achieve the target moisture content is calculated according to the material balance principle.

[0021] In this step, before pressing begins, the operator presets the target moisture content ω_target (e.g., 50%) of the final filter cake through the human-machine interface of controller 3. Controller 3 internally stores the total fixed volume V_total of the filter chambers of the diaphragm filter press body 9 (for a filter press with n chambers, V_total = n × V_chamber, where V_chamber is the volume of a single filter chamber). Based on the material balance principle, controller 3 calculates the target press water injection volume V_squeeze_target required to achieve the target moisture content, based on the oven-dry solids mass M_dry, the target moisture content ω_target, and the total fixed volume V_total. This step transforms the intangible moisture content control problem into a directly measurable and controllable press water volume control problem, achieving a shift in control dimension and providing a clear target value for subsequent closed-loop control.

[0022] S3. During the pressing stage, the pressing pump 15 is started to inject pressing water into the diaphragm chamber, and the actual injection volume V_squeeze_current of the pressing water is monitored in real time using the second electromagnetic flow meter.

[0023] The initial state of the diaphragm cavity 18 before feeding is as follows: Figure 4 As shown, in this step, the state of the diaphragm chamber 18 after feeding is as follows: Figure 5 As shown, controller 3 starts press pump 15, injecting water from press water tank 16 into diaphragm cavity 18 of diaphragm filter plate 17 via press pipe 11. Diaphragm filter plate 17 includes diaphragm substrate 171 and diaphragm sheet 172. Figure 6 As shown, with the injection of pressing water, the pressure in the diaphragm chamber 18 increases, and the diaphragm sheet 172 unfolds on the diaphragm substrate 171, entering a bulging state. This compresses the filter cake in the filter press chamber 19, further squeezing out the water from the filter cake and discharging it from the system through the filtrate discharge pipe 8. The second electromagnetic flowmeter 13, installed on the pressing pipe 11, monitors the instantaneous flow rate of the pressing water in real time and accumulates it to obtain the actual injection volume V_squeeze_current. At the same time, the pressing pressure transmitter 10 monitors the pressing pressure P_current in real time.

[0024] S4. During the pressing process, the actual injection volume V_squeeze_current is compared with the target pressed water injection volume V_squeeze_target. When V_squeeze_current ≥ V_squeeze_target, the pressing process is stopped.

[0025] In this step, controller 3 continuously compares V_squeeze_current with V_squeeze_target. When V_squeeze_current reaches or exceeds V_squeeze_target, controller 3 immediately issues a command to stop the pressing pump 15, ending the pressing process. At this time, controller 3 opens the pressing water return pneumatic valve 12, and the pressing water returns to the pressing water tank 16 through the pressing water return pipeline 14. This step achieves precise control by stopping when the target is reached, ensuring that the moisture content of the sludge cake is precisely controlled near the target value. This completely eliminates the over-pressing operation taken for safety in the traditional mode, thereby significantly shortening the pressing cycle, reducing energy consumption, and extending the service life of core components such as the diaphragm filter plate 17 and filter cloth.

[0026] In a specific embodiment, the calculation of the target press water injection volume V_squeeze_target based on the material balance principle specifically involves: estimating the volume occupied by the oven-dry solids based on the oven-dry solids mass M_dry and its apparent density; subtracting the volume occupied by the oven-dry solids from the total filter chamber volume V_total to obtain the void volume to be filled; and converting the void volume to be filled into the target press water injection volume V_squeeze_target required at the target moisture content ω_target using a preset calibration coefficient.

[0027] In this embodiment, the controller 3 is pre-loaded with a material balance model obtained through experimental calibration. In this step, the total filter chamber volume V_total consists of three parts: the volume occupied by oven-dry solids, the volume occupied by water in the filter cake at the target moisture content, and the void volume that may be filled by pressurized water. Let the apparent density of oven-dry solids be ρ_dry (which can be determined experimentally or input into the controller 3 as a system calibration parameter), then the volume occupied by oven-dry solids is M_dry / ρ_dry. When the target moisture content ω_target is reached, the mass of water in the filter cake M_water_target and the mass of oven-dry solids M_dry satisfy ω_target = M_water_target / (M_dry + M_water_target), from which the volume of water V_water_target (the density of water is taken as 1) can be calculated. The volume filled by pressurized water is essentially the remaining space after deducting the volume of oven-dry solids and their bound water from the total filter chamber volume. Therefore, the target press water injection volume can be calculated using a preset calibration coefficient k (used to correct for differences in material properties, bound water ratio, etc.): V_squeeze_target = k × (V_total - M_dry / ρ_dry - V_water_target). This calibration coefficient can be obtained by fitting experimental data from several batches and continuously optimized in subsequent operations.

[0028] In a specific embodiment, the method further includes: During the pressing stage, based on the material balance principle, the current predicted moisture content ω_current of the current mud cake is calculated in real time according to the actual injection volume V_squeeze_current, and the ω_current is compared with the target moisture content ω_target. The conditions for stopping the pressing process also include: stopping the pressing process when ω_current≤ω_target.

[0029] In this embodiment, the controller 3 not only monitors the volume of pressing water during the pressing process, but also uses the reverse derivation relationship of the material balance model to calculate the current predicted moisture content ω_current of the mud cake in real time based on the injected pressing water volume V_squeeze_current monitored by the second electromagnetic flowmeter 13, and displays it on the operation interface of the controller 3 in real time. This allows the operator or control system to monitor the dehydration status of the mud cake in real time, and can issue an early warning when ω_current approaches ω_target. When ω_current reaches or falls below ω_target, a stop pressing command is also triggered, stopping the pressing pump 15, forming a dual judgment mechanism, which further improves the control accuracy and reliability.

[0030] In a specific embodiment, the real-time back-calculation of the current predicted moisture content ω_current based on the actual injection volume V_squeeze_current is achieved through the inverse function relationship ω_current=f of the material balance principle. -1 (M_dry, V_squeeze_current) is calculated.

[0031] In this embodiment, based on the positive function relationship of the aforementioned material balance model V_squeeze = f(M_dry, ω), its inverse function ω = f can be obtained through mathematical transformation. -1 (M_dry, V_squeeze). Specifically, based on the current injected press water volume V_squeeze_current monitored by the second electromagnetic flowmeter 13, combined with the known oven-dry solids mass M_dry and the total filter chamber volume V_total, the current moisture content ω_current of the filter cake can be derived in reverse in the controller 3. This inverse function relationship can be implemented in the controller 3 through analytical expressions or table lookup, providing a direct mathematical basis for real-time prediction of moisture content.

[0032] In a specific embodiment, the method further includes a security control step: Set the maximum allowable pressing water volume V_squeeze_max and / or the maximum allowable pressing pressure P_max; During the pressing process, if the actual injection volume V_squeeze_current reaches V_squeeze_max, or the pressing pipeline pressure reaches P_max, the pressing process is immediately stopped.

[0033] In this embodiment, to prevent abnormal situations caused by model deviations, extreme operating conditions, or equipment failures, the system is equipped with dual safety limits. V_squeeze_max can be set to 90% of the total filter chamber volume, and P_max is set according to the rated pressure bearing capacity of the diaphragm filter plate 17 (e.g., 1.2 MPa). During the pressing process, as long as V_squeeze_current monitored by the second electromagnetic flowmeter 13 reaches V_squeeze_max, or the pressure P_current monitored by the pressing pressure transmitter 10 reaches P_max, the controller 3 will ignore the main stop condition, immediately and forcibly stop the pressing pump 15, and issue an alarm, prioritizing equipment safety and personal safety. This safety fault-tolerant mechanism provides a reliable guarantee for the long-term stable operation of the system.

[0034] In a specific embodiment, at the end of the pressing process, when the current predicted moisture content ω_current is close to the target moisture content ω_target, the operating frequency of the pressing pump is reduced, so that the pressing level is slowly injected until it stops.

[0035] In this embodiment, to achieve flexible control of the pressing process and reduce hydraulic shock to the pressing pump 15, pressing pipeline 11, and diaphragm filter plate 17, the controller 3 employs a frequency conversion control strategy at the end of the pressing process. When the ω_current calculated by the controller 3 approaches ω_target (e.g., differing by 2%), the controller 3 outputs a signal to reduce the operating frequency of the pressing pump 15, thereby reducing the flow rate of pressing water and slowly injecting it into the diaphragm chamber 18 through the pressing pipeline 11 until the stopping condition is met and the pump stops smoothly. This soft-stop method effectively avoids pressure fluctuations and water hammer phenomena caused by sudden pump stoppage, protects the core components of the system, and extends the service life of the equipment.

[0036] In a specific embodiment, the method further includes a model self-optimization step: Store the oven-dry solids mass M_dry, actual pressed water volume V_squeeze_current, and predicted moisture content ω_current data for each work cycle; Obtain the measured moisture content of the mud cake after unloading; The predicted moisture content is compared with the measured moisture content, and the calibration coefficient in the material balance principle is automatically fine-tuned based on the comparison result.

[0037] In this embodiment, the system automatically records key data for each work cycle through controller 3, including the oven-dry solids mass M_dry, the actual squeezed water volume V_squeeze_current monitored by the second electromagnetic flowmeter 13, and the predicted moisture content ω_current calculated by controller 3, forming big data on the process. Operators input the laboratory-measured moisture content of the sludge cake after unloading into controller 3, which periodically compares the predicted moisture content ω_current with the measured value. If a systematic deviation is found (e.g., multiple consecutive batches of predicted values ​​are all 2% higher), the calibration coefficient k in the material balance model is automatically fine-tuned, resulting in increasingly higher prediction and control accuracy for subsequent batches. This self-optimization function not only achieves continuous improvement in control accuracy but can also be used to analyze the changing trends of the feed sludge characteristics, optimize the dosage of flocculant conditioning agents, and provide early warnings of filter cloth clogging or damage (when there is a systematic deviation between the actual V_squeeze_target and the theoretical value), providing data for predictive maintenance of the equipment and forming a virtuous cycle of intelligent learning mechanism.

[0038] In one specific embodiment, the present invention supports multi-scenario applications of refined and flexible manufacturing: (1) Range control: It can easily achieve precise control of moisture content within a specific range (such as 48%-52%), rather than simply lower as much as possible, to meet the differentiated needs of different treatment scenarios.

[0039] (2) Formulated production: For different disposal options (such as incineration requiring a moisture content of ≤40%, landfill requiring a moisture content of ≤60%, and building material utilization requiring a moisture content of ≤45%), multiple process formulas can be preset in the controller 3, and the target moisture content ω_target can be switched with one click to achieve flexible production.

[0040] (3) Data-driven optimization: The key data such as M_dry, V_squeeze, and ω_current recorded by the controller 3 can be used to analyze the characteristic change trend of the feed sludge and provide data support for process optimization.

[0041] like Figure 3 As shown, this embodiment of the invention also provides a diaphragm filter press cake moisture content control system, comprising: The diaphragm filter press body 9 has a filter chamber with a fixed total volume V_total; The feed pipeline 7 is equipped with an online sludge concentration meter 4 and a first electromagnetic flow meter 5. The pressing water pipeline 11 is equipped with a second electromagnetic flow meter 13 and a pressing pump 15. The controller 3 is electrically connected to the online sludge concentration meter 4, the first electromagnetic flow meter 5, the second electromagnetic flow meter 13 and the press pump 15 respectively; The controller 3 is configured to perform the steps of the above method.

[0042] In a specific embodiment, the pressing water pipeline 11 is also equipped with a pressing pressure transmitter 10, which is electrically connected to the controller 3 and is used to monitor the pressing pressure.

[0043] In this embodiment, the system integrates high-precision online detection instruments, including an online sludge concentration meter 4, a first electromagnetic flow meter 5, a second electromagnetic flow meter 13, a pressing pressure transmitter 10, and actuators including a sludge feed pump 2 and a pressing pump 15, which are uniformly coordinated and controlled by a controller 3 to form a complete closed-loop control system.

[0044] It should be noted that those skilled in the art can clearly understand that the specific execution process of the controller in the above-mentioned diaphragm filter press cake moisture content control system can be referred to the corresponding description in the aforementioned method embodiments. For the sake of convenience and brevity, it will not be repeated here.

[0045] The controller in the above-mentioned diaphragm filter press cake moisture content control system can be implemented as a computer program that can run on the controller.

[0046] It will be understood by those skilled in the art that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program may be stored in a storage medium, which is a computer-readable storage medium. The computer program is executed by at least one processor in the computer system to implement the process steps of the embodiments of the above methods.

[0047] Therefore, the present invention also provides a storage medium. This storage medium can be a computer-readable storage medium. The storage medium stores a computer program. When executed by a processor, the computer program causes the processor to perform the following steps: S1. During the feeding stage, the feed sludge concentration C monitored by the online sludge concentration meter and the feed sludge instantaneous flow rate dV monitored by the first electromagnetic flow meter are obtained in real time, and the total dry solid mass M_dry entering the filter chamber of the filter press is calculated and determined in real time according to the formula M_dry=∫(C×dV). S2. Before pressing begins, based on the preset final target moisture content of the mud cake ω_target, the total mass of the oven-dry solids M_dry, and the total fixed volume of the filter chamber of the filter press V_total, the target pressing water injection volume V_squeeze_target required to achieve the target moisture content is calculated according to the material balance principle. S3. During the pressing stage, start the pressing pump to inject pressing water into the diaphragm chamber, and use the second electromagnetic flowmeter to monitor the actual injection volume V_squeeze_current of the pressing water in real time. S4. During the pressing process, the actual injection volume V_squeeze_current is compared with the target pressed water injection volume V_squeeze_target. When V_squeeze_current ≥ V_squeeze_target, the pressing process is stopped.

[0048] The storage medium is a physical, non-transient storage medium, such as a USB flash drive, portable hard drive, read-only memory (ROM), magnetic disk, or optical disk, or any other physical storage medium capable of storing program code.

[0049] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0050] In the several embodiments provided by this invention, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For example, the division of each unit is merely a logical functional division, and there may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.

[0051] The steps in the method of this invention can be adjusted, merged, or reduced in order according to actual needs. The units in the device of this invention can be merged, divided, or reduced according to actual needs. Furthermore, the functional units in the various embodiments of this invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0052] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, a terminal, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention.

[0053] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0054] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Since these modifications and variations fall within the scope of the claims and their equivalents, this invention also intends to include these modifications and variations.

[0055] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for controlling the moisture content of filter cake in a diaphragm filter press, characterized in that, The controller performs the following steps: During the feeding stage, the feed sludge concentration C monitored by the online sludge concentration meter and the feed sludge instantaneous flow rate dV monitored by the first electromagnetic flow meter are acquired in real time, and the total dry solid mass M_dry entering the filter chamber of the filter press is calculated and determined in real time according to the formula M_dry=∫(C×dV). Before pressing begins, the target pressing water injection volume V_squeeze_target required to achieve the target moisture content is calculated based on the material balance principle, according to the preset final target moisture content ω_target, the total mass of the oven-dry solids M_dry, and the total fixed volume V_total of the filter chamber of the filter press. During the pressing stage, the pressing pump is started to inject pressing water into the diaphragm chamber, and the actual injection volume V_squeeze_current of the pressing water is monitored in real time using the second electromagnetic flow meter. During the pressing process, the actual injection volume V_squeeze_current is compared with the target pressed water injection volume V_squeeze_target. When V_squeeze_current ≥ V_squeeze_target, the pressing process is stopped.

2. The method for controlling the moisture content of filter cake in a diaphragm filter press according to claim 1, characterized in that, The calculation of the target press water injection volume V_squeeze_target based on the material balance principle is as follows: the volume occupied by the oven-dry solids is estimated based on the oven-dry solids mass M_dry and its apparent density; the volume of the voids to be filled is obtained by subtracting the volume occupied by the oven-dry solids from the total filter chamber volume V_total; and the voids to be filled are converted into the target press water injection volume V_squeeze_target required at the target moisture content ω_target using a preset calibration coefficient.

3. The method for controlling the moisture content of filter cake in a diaphragm filter press according to claim 1, characterized in that, The method further includes: During the pressing stage, based on the material balance principle, the current predicted moisture content ω_current of the current mud cake is calculated in real time according to the actual injection volume V_squeeze_current, and the ω_current is compared with the target moisture content ω_target. The conditions for stopping the pressing process also include: stopping the pressing process when ω_current≤ω_target.

4. The method for controlling the moisture content of filter cake in a diaphragm filter press according to claim 3, characterized in that, The real-time back-calculation of the current predicted moisture content ω_current based on the actual injected volume V_squeeze_current is achieved through the inverse function relationship ω_current=f of the material balance principle. -1 (M_dry, V_squeeze_current) is calculated.

5. The method for controlling the moisture content of filter cake in a diaphragm filter press according to claim 1, characterized in that, It also includes safety control steps: Set the maximum allowable pressing water volume V_squeeze_max and / or the maximum allowable pressing pressure P_max; During the pressing process, if the actual injection volume V_squeeze_current reaches V_squeeze_max, or the pressing pipeline pressure reaches P_max, the pressing process is immediately stopped.

6. The method for controlling the moisture content of filter cake in a diaphragm filter press according to claim 3, characterized in that, Towards the end of the pressing process, when the current predicted moisture content ω_current approaches the target moisture content ω_target, the operating frequency of the pressing pump is reduced, allowing the pressing level to be injected slowly until it stops.

7. The method for controlling the moisture content of diaphragm filter press cake according to any one of claims 1 to 6, characterized in that, It also includes a model self-optimization step: Store the oven-dry solids mass M_dry, actual pressed water volume V_squeeze_current, and predicted moisture content ω_current data for each work cycle; Obtain the measured moisture content of the mud cake after unloading; The predicted moisture content is compared with the measured moisture content, and the calibration coefficient in the material balance principle is automatically fine-tuned based on the comparison result.

8. A control system for the moisture content of filter cake in a diaphragm filter press, characterized in that, include: The main body of the diaphragm filter press has filter chambers with a fixed total volume V_total; The feed pipeline is equipped with an online sludge concentration meter and a first electromagnetic flow meter; The pressing water pipeline is equipped with a second electromagnetic flow meter and a pressing pump; The controller is electrically connected to the online sludge concentration meter, the first electromagnetic flow meter, the second electromagnetic flow meter, and the press pump, respectively. The controller is configured to perform the steps of the method according to any one of claims 1 to 7.

9. The system according to claim 8, characterized in that, The pressing water pipeline is also equipped with a pressure transmitter, which is electrically connected to the controller and is used to monitor the pressing pressure.

10. A storage medium, characterized in that, The storage medium stores a computer program that, when executed by a processor, can implement the steps of the method as described in any one of claims 1 to 7.

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