Sludge low-temperature vacuum dewatering and drying control method and system

Abstract

The present application provides a kind of sludge low-temperature vacuum dewatering and drying control method and system, it is related to sludge treatment technical field, method includes: to be treated sludge is carried out into sludge pretreatment state characterization, obtains batch state data set of into sludge;Carry out batch drying load typing, obtain drying load grade, and configure basic operating parameters;Carry out batch into sludge control, and according to the filtrate discharge state and filter plate pressure difference state in the process of into sludge generation solid interception evaluation result;Obtain batch cake forming parameter;Carry out heat vacuum synergic dewatering control, obtain batch drying process data;Carry out dewatering rate attenuation identification, generate drying termination determination result, and generate next batch operation correction parameter.The present application solves the technical problem that present technology generally uses fixed operating parameters to carry out sludge dewatering and drying control, leading to different batches of sludge cannot be realized targeted regulation, in turn leading to part batch cake moisture content fluctuation is larger, drying efficiency declines.

Description

Technical Field

[0001] This invention relates to the field of sludge treatment technology, specifically to a method and system for controlling low-temperature vacuum dewatering and drying of sludge. Background Technology

[0002] With the continuous expansion of urban wastewater treatment scale and the sustained increase in sludge production, the pressure on sludge reduction and stabilization is constantly increasing. Existing technologies typically use fixed operating parameters for sludge dewatering and drying control, which makes it impossible to achieve targeted adjustments when different batches of sludge experience variations in organic matter content, sludge concentration, and feed rate. This results in significant fluctuations in the moisture content of some batches of sludge cake and a decrease in drying efficiency, especially during the dry season when the proportion of organic matter in the sludge increases, leading to a marked reduction in drying efficiency.

[0003] Relevant data shows that changes in organic matter content are generally inversely proportional to drying efficiency; that is, the higher the organic matter content, the lower the drying efficiency, especially during the dry season when the influent concentration is high. The organic matter content is approximately 0.55% during the rainy season, while it can reach a maximum of 0.69% during the dry season, an increase of nearly 25%. Consequently, the drying efficiency drops from 50.88 kg water / (kW·h) during the rainy season to 25.12 kg water / (kW·h), a decrease of 50.6%. Summary of the Invention

[0004] This application provides a method and system for controlling the low-temperature vacuum dewatering and drying of sludge, which aims to solve the technical problem that the existing technology usually uses fixed operating parameters for sludge dewatering and drying control, which makes it impossible to achieve targeted adjustment for different batches of sludge, resulting in large fluctuations in the moisture content of some batches of sludge cake and a decrease in drying efficiency.

[0005] The first aspect disclosed in this application provides a method for controlling the low-temperature vacuum dewatering and drying of sludge. The method includes: characterizing the pretreatment state of the sludge to be treated to obtain a batch sludge infeed state dataset; classifying the batch drying load based on the batch sludge infeed state dataset to obtain a drying load level, and configuring basic operating parameters, including sludge infeed control parameters, pressing control parameters, low-temperature heating parameters, and vacuum maintenance parameters; controlling the batch sludge infeed according to the sludge infeed control parameters, and generating a solids retention evaluation result based on the filtrate discharge state and filter plate pressure difference state during the sludge infeed process; correcting the pressing control parameters based on the solids retention evaluation result to obtain batch cake forming parameters; performing thermal vacuum coordinated dewatering control based on the batch cake forming parameters, low-temperature heating parameters, and vacuum maintenance parameters to obtain batch drying process data; identifying the dewatering rate decay based on the batch drying process data, generating a drying termination determination result, and generating the next batch operation correction parameters based on the cake moisture content distribution after unloading.

[0006] The second aspect of this application discloses a sludge low-temperature vacuum dewatering and drying control system. The system is used in the aforementioned sludge low-temperature vacuum dewatering and drying control method. The system includes: a state characterization module for characterizing the pretreatment state of the sludge to be treated, obtaining a batch sludge infeed state dataset; a load classification module for classifying the batch drying load based on the batch sludge infeed state dataset, obtaining a drying load level, and configuring basic operating parameters, including sludge infeed control parameters, pressing control parameters, low-temperature heating parameters, and vacuum maintenance parameters; and a sludge infeed control module for batch drying according to the sludge infeed control parameters. The system includes a primary mud-feeding control module, which generates a solids retention evaluation result based on the filtrate discharge status and filter plate pressure difference during the mud-feeding process; a parameter correction module, which corrects the pressing control parameters based on the solids retention evaluation result to obtain batch cake forming parameters; a dehydration control module, which performs thermal-vacuum coordinated dehydration control based on the batch cake forming parameters, low-temperature heating parameters, and vacuum maintenance parameters to obtain batch drying process data; and an attenuation identification module, which identifies the dehydration rate attenuation based on the batch drying process data, generates a drying termination determination result, and generates the next batch operation correction parameters based on the moisture content distribution of the unloaded cake.

[0007] One or more technical solutions provided in this application have at least the following beneficial effects: By comprehensively characterizing the state of the sludge pretreatment stage, the dewatering characteristics and treatment difficulty of different batches of sludge can be identified in advance, thus providing basic data support for subsequent drying load classification and operating parameter configuration, improving the system's targeting and stability. By classifying the drying load of different batches of sludge and matching corresponding parameters, the operating intensity can be automatically adjusted according to the sludge load status, avoiding the problem of excessively thick sludge cake under high load conditions or energy waste under low load conditions, and improving the efficiency of low-temperature vacuum dewatering and drying. By analyzing the solid content of the filtrate and the pressure difference of the filter plates in real time during the sludge feeding stage, problems such as sludge particle loss, unstable sludge cake structure, or filter plate blockage can be identified in a timely manner, improving the sludge retention effect and reducing the impact of filtrate recirculation on the biological system. By dynamically adjusting the solid retention status, the system can achieve the desired results. The positive flow rate of sludge, pressing time, and pressing pressure make the sludge cake formation process more stable. At the same time, the sludge cake structure is optimized by combining the back calculation results of sludge cake thickness, which can reduce the problem of excessive moisture content caused by excessively thick local sludge cake and improve the uniformity of subsequent hot vacuum dehydration. By coordinating the control of hot water supply and vacuum dehydration, the water in the sludge is rapidly vaporized and separated under low temperature and negative pressure conditions, thereby reducing overall energy consumption and improving sludge cake dehydration efficiency and drying stability. The engineering operation results show that the sludge cake moisture content can be stably controlled below 40%. By analyzing the dehydration rate decay state and sludge cake moisture content distribution, the optimal drying termination time can be automatically identified, and the operating parameters for the next batch can be adaptively corrected, thereby improving the continuous operation stability of the system, reducing energy and chemical consumption, and maintaining the long-term stability of sludge cake moisture content.

[0008] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of a sludge low-temperature vacuum dewatering and drying control method provided in an embodiment of this application.

[0010] Figure 2 This is a schematic diagram of a sludge low-temperature vacuum dewatering and drying control system provided in an embodiment of this application.

[0011] Explanation of reference numerals in the attached diagram: 10 for state characterization module, 20 for load classification module, 30 for sludge feed control module, 40 for parameter correction module, 50 for dewatering control module, and 60 for attenuation identification module. Detailed Implementation

[0012] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0013] Example 1, as Figure 1 As shown in the embodiment of this application, a method for controlling the low-temperature vacuum dewatering and drying of sludge is provided, the method comprising: The pretreatment state of the sludge to be treated was characterized to obtain a batch sludge infeed state dataset.

[0014] The system acquires operational parameters for sludge during gravity thickening, mechanical thickening, and sludge conditioning stages, including influent sludge moisture content, effluent sludge moisture content, sludge concentration, thickening flow rate, flocculant dosage, coagulant dosage, and conditioning retention time. These parameters, combined with the rheological state of the conditioned sludge, organic matter ratio, and batch feed volume, comprehensively characterize the dewatering properties of the current batch of sludge. Subsequently, the parameters are associated and stored according to batch number to form a corresponding batch feed status dataset, reflecting the thickening stability, conditioning adaptability, and subsequent drying difficulty of the current batch of sludge.

[0015] Based on the batch mud feeding status dataset, batch drying load is classified to obtain drying load level, and basic operating parameters are configured, including mud feeding control parameters, pressing control parameters, low temperature heating parameters, and vacuum maintenance parameters.

[0016] The dry-basis load for the current batch is calculated based on sludge concentration, influent sludge moisture content, batch sludge volume, and organic matter ratio. A drying load characteristic is then constructed by combining this characteristic with pretreatment dewatering contribution, concentration stability coefficient, and conditioning adaptability coefficient. This characteristic is matched with preset low-load, medium-load, and high-load operating samples to determine the drying load level of the current batch. Based on different load levels, the corresponding influent sludge flow rate, pressing holding time, hot water circulation intensity, and vacuum holding time are automatically configured to adapt to the dewatering and drying requirements under different sludge conditions.

[0017] Batch sludge feeding is controlled according to the sludge feeding control parameters, and solids retention evaluation results are generated based on the filtrate discharge status and filter plate pressure difference status during the sludge feeding process.

[0018] During the sludge feeding process, sludge is fed into the low-temperature vacuum dewatering and drying integrated machine according to the set sludge feed flow rate. The concentration of suspended solids in the filtrate, the filtrate discharge rate, and the pressure difference of the filter plates are monitored in real time at different stages. By statistically analyzing the amount of solids lost in the filtrate and calculating the solids retention deviation based on the dry basis load, the retention effect of the sludge during the filter press process is assessed. When the solids content of the filtrate increases or the pressure difference fluctuates abnormally, it indicates that there is an unstable cake structure or fine particle loss problem, thus generating a corresponding solids retention evaluation result.

[0019] The pressing control parameters are corrected based on the solids retention evaluation results to obtain batch cake forming parameters.

[0020] Based on the solids retention deviation, the feed flow rate, flocculant compensation amount, and pressing holding time are dynamically corrected. Simultaneously, the pressing pressure ramp-up process is adjusted in conjunction with the peak pressure difference of the filter plates to improve the cake compaction effect. The cake thickness is calculated back-calculated based on the filtrate discharge, filter plate pressure difference, and dry basis load at the end of the pressing stage. The cake thickness, pressing holding time, and reagent correction amount are then integrated to obtain the cake forming parameters corresponding to the current batch, which are used for subsequent thermal vacuum synergistic dehydration control.

[0021] Based on the batch cake forming parameters, low-temperature heating parameters, and vacuum maintenance parameters, thermal vacuum synergistic dehydration control is performed to obtain batch drying process data.

[0022] The appropriate heating and vacuum range within the filter chamber is determined based on the sludge cake thickness. A hot water circulation system continuously heats the filter plates, while simultaneously activating the vacuum system to reduce the pressure in the drying chamber, allowing the moisture in the sludge to vaporize and separate under low-temperature conditions. During operation, parameters such as the inlet and outlet water temperatures of the filter plates, hot water circulation flow rate, vacuum pressure, vacuum pump operating frequency, and condensate discharge are collected in real time and correlated over time to form batch drying process data. This data reflects the heating status, moisture vaporization status, and vacuum dehydration status of the current batch of sludge.

[0023] Based on the batch drying process data, the dehydration rate decay is identified, a drying termination determination result is generated, and the next batch operation correction parameters are generated based on the moisture content distribution of the mud cake after unloading.

[0024] The dewatering rate per unit time is calculated based on the condensate discharge volume over a continuous period, and the decreasing trend of the dewatering rate is further calculated. When the dewatering rate per unit time continues to decrease and falls below a preset threshold, the current batch of sludge is considered to be nearing the drying endpoint. For high-load batches, the vacuum holding time is appropriately extended before reassessing the dewatering capacity. After unloading, the moisture content of the sludge cake at different filter plate positions and in the central and edge areas is measured to analyze the differences in moisture content distribution. Based on the test results, the sludge inflow rate, sludge cake thickness limit, pressing holding time, and vacuum holding time for the next batch are adjusted to form adaptive operation correction parameters for the next batch.

[0025] Furthermore, the pretreatment state of the sludge to be treated is characterized to obtain a batch sludge infeed state dataset, including: The following steps are taken: First, obtain the influent sludge moisture content, effluent sludge moisture content, and throughput per unit time of the sludge pretreatment unit, and calculate the pretreatment dewatering contribution. Second, obtain the sludge concentration, thickening influent flow rate, and flocculant dosage ratio of the mechanical thickening unit, and calculate the thickening stability coefficient. Third, obtain the coagulant dosage ratio, flocculant compensation dosage ratio, conditioning retention time, and post-conditioning sludge rheological parameters of the sludge conditioning unit, and calculate the conditioning fit coefficient. Fourth, obtain the organic matter ratio and batch influent volume of the sludge to be treated, and combine these with the pretreatment dewatering contribution, thickening stability coefficient, and conditioning fit coefficient, associating them according to batch number to form the batch influent status dataset.

[0026] The moisture content data of sludge before and after entering the pretreatment stage is obtained by an online moisture content detection device installed in the gravity thickening unit or pre-dewatering unit. At the same time, the amount of sludge processed per unit time is collected. Based on the correspondence between the water removal ratio before and after treatment and the processing volume, the dewatering contribution of the current batch of sludge in the pretreatment stage is calculated, which is used to reflect the reduction effect of the pretreatment stage on the load of subsequent low temperature vacuum dewatering and drying.

[0027] The concentration information of the mechanically thickened sludge is obtained by a concentration detector. Simultaneously, the sludge inflow rate and the real-time flocculant dosage are collected. Based on the stability of sludge concentration changes, the thickening efficiency per unit flow rate, and the adaptability of flocculant dosage, a comprehensive analysis of the current batch's mechanical thickening operation status is performed to generate a thickening stability coefficient. This coefficient reflects the particle aggregation capacity of the sludge during the mechanical thickening stage and its structural stability during subsequent filtration.

[0028] After the sludge enters the conditioning tank, the dosage of coagulant, the amount of flocculant compensation dosage, and the residence time of the sludge in the conditioning tank are collected. At the same time, rheological parameters such as viscosity, flowability, or shear response of the conditioned sludge are detected. Based on the degree of matching between the dosage of the agents and the rheological state of the sludge, the conditioning adaptation coefficient is calculated to reflect the adaptability of the current sludge conditioning state to the subsequent sludge cake forming and thermal vacuum dewatering process.

[0029] The organic matter content of the sludge is obtained by detecting the ratio of volatile suspended solids to mixed liquor suspended solids. A higher ratio indicates a higher proportion of organic matter in the sludge. The actual sludge intake for the current batch is also collected. The parameter results from each stage are uniformly correlated and stored according to the same batch number to construct a corresponding batch sludge intake status dataset. This dataset is used to comprehensively characterize the dewatering characteristics, conditioning state, and drying load level of the current batch of sludge, providing basic data support for subsequent drying load classification and operating parameter configuration. Research shows that changes in sludge organic matter content directly affect the efficiency of low-temperature vacuum dewatering and drying; therefore, incorporating the organic matter ratio into the batch status characterization can improve the accuracy of subsequent operational control.

[0030] Furthermore, based on the batch sludge inlet status dataset, batch drying load classification is performed to obtain drying load levels, including: The dry basis load of the current batch is calculated based on the sludge concentration, sludge moisture content, and batch sludge intake. A drying load feature vector is constructed based on the dry basis load, organic matter ratio, pretreatment dewatering contribution, concentration stability coefficient, and conditioning adaptation coefficient. The similarity of the drying load feature vector with preset low load samples, preset medium load samples, and preset high load samples is calculated to obtain multiple load similarities. The load sample category corresponding to the maximum load similarity is selected as the drying load level. The drying load level is identified by sludge intake limit, sludge cake thickness limit, heating intensity limit, and vacuum retention limit.

[0031] The sludge concentration parameters after mechanical thickening and sludge conditioning are obtained, and combined with the influent moisture content and actual influent volume of the current batch of sludge, the corresponding oven-dry sludge volume for the current batch is calculated to characterize the actual solids load level entering the low-temperature vacuum dewatering and drying system. The dry-basis load reflects the processing intensity requirements of the current batch of sludge during subsequent pressing and thermal vacuum dewatering processes. A higher dry-basis load indicates that more water needs to be removed per unit batch, and the system's operating load increases accordingly. Based on the engineering operation, the low-temperature vacuum dewatering and drying system operates in batch mode; changes in the sludge volume and concentration of different batches directly affect the subsequent drying efficiency.

[0032] Multiple parameters reflecting the difficulty and operational stability of sludge dewatering are correlated and linked together to form a corresponding drying load feature vector according to a preset data structure. Among these, the dry basis load characterizes the actual treatment load of the current batch, the organic matter ratio reflects the organic component content in the sludge, the pretreatment dewatering contribution characterizes the effect of the preceding dewatering stage, the concentration stability coefficient reflects the operational stability of the mechanical concentration stage, and the conditioning adaptability coefficient reflects the sludge's adaptability to chemical conditioning. By combining these parameters, load characteristic data that comprehensively reflects the drying characteristics of the current batch of sludge is formed. Studies have shown that the efficiency of low-temperature vacuum dewatering and drying decreases significantly when the organic matter content of the sludge increases; therefore, incorporating the organic matter ratio into the load feature vector can improve the accuracy of load classification.

[0033] A historical sample database under different operating load conditions is pre-established. Each historical sample contains parameters such as sludge concentration, organic matter ratio, chemical conditioning status, and final drying effect for the corresponding batch. After the drying load feature vector generated for the current batch is input, it is matched with various load samples. By calculating the degree of difference between features, the corresponding load similarity is obtained to determine whether the current batch of sludge is closer to a low-load, medium-load, or high-load operating state, thereby improving the targeting of subsequent operating parameter configurations.

[0034] When the similarity of samples in a certain load category is the highest, that category is determined as the drying load level corresponding to the current batch. Based on this level, limits for sludge feed rate, cake thickness, heating intensity, and vacuum holding time are automatically configured. Specifically, low load levels correspond to higher sludge feed rates and shorter vacuum holding times, while high load levels correspond to lower sludge feed rates, higher heating intensity, and longer vacuum holding times. This adapts to the dewatering and drying requirements under different sludge load conditions, ensuring that the final moisture content of the cake consistently reaches the target range.

[0035] Furthermore, configure basic operating parameters, including: When the drying load level is low, a first sludge inlet flow rate, a first pressing hold time, a first hot water circulation flow rate, and a first vacuum hold time are configured; when the drying load level is medium, a second sludge inlet flow rate, a second pressing hold time, a second hot water circulation flow rate, and a second vacuum hold time are configured; when the drying load level is high, a third sludge inlet flow rate, a third pressing hold time, a third hot water circulation flow rate, and a third vacuum hold time are configured; wherein, the third sludge inlet flow rate is less than the second sludge inlet flow rate, the second sludge inlet flow rate is less than the first sludge inlet flow rate, the third vacuum hold time is greater than the second vacuum hold time, and the second vacuum hold time is greater than the first vacuum hold time.

[0036] When the dry basis load of the current batch of sludge is determined to be low, the organic matter content of the sludge is low, and the pretreatment dewatering effect is good, it indicates that the dewatering difficulty of the current batch of sludge is relatively low. Therefore, a larger sludge flow rate is allowed for rapid sludge feeding, while the pressing holding time and vacuum holding time are appropriately shortened to improve the single-batch processing efficiency of the equipment. During the heating phase, a lower hot water circulation flow rate is configured to enable the sludge to complete thermal vacuum synergistic dewatering in a shorter time, thereby reducing overall energy consumption and operating costs. Based on actual engineering operation, when the sludge load is low, the low-temperature vacuum dewatering and drying system can maintain a high drying efficiency and a relatively stable sludge moisture content.

[0037] When the organic matter ratio, sludge concentration, and dry basis load of the current batch of sludge are within the normal operating range, medium-intensity sludge feeding and pressing parameters are adopted to ensure uniform and stable sludge cake formation. At the same time, corresponding hot water circulation flow rate and vacuum holding time are adopted to allow the moisture in the sludge to be gradually vaporized and removed under a stable negative pressure environment, thereby balancing drying efficiency and equipment operation stability, and avoiding increased system energy consumption due to excessive heating or excessively long vacuum time.

[0038] When the current batch of sludge is identified as having a large feed volume, a high organic matter ratio, or poor conditioning adaptability, it is determined that the current batch is operating under high load. In this case, to avoid excessively thick sludge cake, uneven internal heat transfer, and difficulty in moisture vaporization and removal, the feed flow rate is reduced, and the pressing holding time is appropriately extended to allow the sludge to form a more stable cake structure during the filter press stage. Simultaneously, the hot water circulation intensity is increased, and the vacuum holding time is extended to enhance the internal moisture migration and vaporization removal capacity of the sludge, thereby improving the final drying effect. Studies have shown that when the organic matter content of the sludge increases, the efficiency of low-temperature vacuum dewatering and drying decreases significantly; therefore, under high load conditions, the vacuum dewatering time needs to be extended.

[0039] As the drying load level is gradually increased from low to high, the sludge feed rate per unit time is gradually reduced to control the cake thickness and filter press load in the filter chamber. At the same time, the vacuum holding time is gradually increased so that the bound water in the sludge can be fully vaporized and discharged under low temperature and negative pressure conditions, thereby ensuring that the target cake moisture content can be stably achieved under different operating load conditions.

[0040] Furthermore, solids retention evaluation results are generated based on the filtrate discharge status and filter plate pressure difference status during the sludge feeding process, including: The batch sludge feeding process is divided into an initial filling stage, a differential pressure establishment stage, and a sludge feeding termination stage according to the sludge inlet flow rate. The filtrate suspended solids concentration, filtrate discharge rate, filter plate differential pressure change rate, and filter plate differential pressure peak value are obtained for each of the three stages. The batch filtrate solids loss is calculated based on the filtrate suspended solids concentration and filtrate discharge rate at each stage. The solids retention deviation is calculated based on the ratio of the batch filtrate solids loss to the dry basis load. The solids retention evaluation result is generated based on the solids retention deviation, the filter plate differential pressure change rate, and the filter plate differential pressure peak value.

[0041] After the sludge enters the low-temperature vacuum dewatering and drying integrated machine, the entire sludge feeding stage is segmented and controlled based on changes in the sludge flow rate and the pressure build-up process within the filter chamber. The initial filling stage is characterized by rapid filling of the filter chamber, during which the sludge flow rate is relatively high. The pressure differential establishment stage involves the gradual formation of a sludge cake inside the filter plates and the establishment of a pressure differential. The final sludge feeding stage is characterized by a gradual decrease in the sludge flow rate and the completion of sludge cake filling. By dividing the process into different stages, the accuracy of subsequent filtrate state analysis and sludge cake formation state identification can be improved.

[0042] During each sludge feeding stage, the suspended solids concentration and filtrate discharge volume in the filtrate are obtained through a filtrate detection device, and the pressure difference changes across the filter plates are collected in real time through a pressure detection device to obtain the filter plate pressure difference change rate and peak pressure difference of the corresponding stage. Among them, the filtrate suspended solids concentration is used to reflect the sludge particle loss, the filter plate pressure difference change rate is used to reflect the cake formation rate and clogging status, and the peak pressure difference of the filter plates is used to reflect the maximum pressing load during the filter press process.

[0043] The suspended solids concentration and corresponding filtrate discharge volume in the filtrate at each stage were statistically analyzed, and the solids loss at each stage was cumulatively calculated to obtain the total solids loss of the current batch of sludge during the filter press process. This method reflects the retention capacity of the low-temperature vacuum dewatering and drying integrated machine for sludge particles. The results show that the solids loss of the batch filtrate during actual operation accounts for approximately 0.66% of the batch's oven-dried sludge volume, indicating that the system has a good sludge retention effect.

[0044] The solids loss of the filtrate calculated for the current batch is compared with the dry basis load of the corresponding batch to obtain the solids retention deviation of the current batch of sludge during the filter press process. When this ratio increases, it indicates that the loss of sludge particles has increased, which may be due to unstable sludge cake structure, insufficient flocculation effect, or decreased filter plate retention capacity. When this ratio is low, it indicates that the retention status of the current batch of sludge is relatively stable.

[0045] By comprehensively analyzing the degree of solids loss, cake formation rate, and pressure changes of the current batch, the retention effect of sludge during the filtration process is evaluated. When the solids retention deviation is large and the pressure difference of the filter plate fluctuates significantly, it is determined that the current batch has a risk of unstable cake formation or particle loss; when the solids retention deviation is small and the pressure difference changes steadily, it is determined that the cake formation of the current batch is good, and the corresponding evaluation results are used to correct subsequent pressing control parameters.

[0046] Furthermore, the pressing control parameters are corrected based on the solids retention evaluation results to obtain batch cake forming parameters, including: Based on the deviation of the solid retention deviation from the preset retention deviation threshold, a sludge flow constraint correction and a flocculant compensation correction are generated; based on the deviation of the filter plate pressure difference change rate from the preset pressure difference change rate threshold, a pressing hold time correction is generated; based on the deviation of the filter plate pressure difference peak value from the preset pressure difference threshold, a pressing pressure rise correction is generated; based on the filtrate discharge at the end of pressing, the filter plate pressure difference, and the dry basis load, the cake thickness is back-calculated to obtain an estimated cake thickness; the estimated cake thickness, the sludge flow constraint correction, the flocculant compensation correction, the pressing hold time correction, and the pressing pressure rise correction are fused to generate the batch cake forming parameters.

[0047] The calculated solids retention deviation for the current batch is compared with the preset allowable retention deviation range. When the solids loss exceeds the preset range, it indicates a decrease in sludge particle retention efficiency. The subsequent sludge inflow rate is reduced accordingly to slow sludge accumulation within the filter chamber. Simultaneously, the flocculant dosage is increased to enhance the flocculation and binding capacity between sludge particles, improving the stability of the sludge cake structure. When the solids retention deviation is small, the current sludge inflow and reagent dosage are maintained to ensure stable system operation. Combined with engineering operation data, changes in filtrate solids content directly reflect the sludge retention efficiency and sludge cake formation status.

[0048] By analyzing the rate of pressure difference buildup on the filter plates, the formation state of the sludge cake during the filter press stage can be determined. When the rate of change of the filter plate pressure difference is relatively fast, it indicates that the sludge cake is forming quickly, and the pressing and holding time should be appropriately shortened. When the rate of change of the filter plate pressure difference is relatively slow, it indicates that the drainage of water inside the sludge is obstructed or the sludge cake structure is relatively loose, so the pressing and holding time should be extended to improve the compaction degree of the sludge cake and the subsequent thermal vacuum dewatering effect.

[0049] During the pressing process, the peak pressure difference of the filter plate is acquired in real time and compared with the preset pressure difference threshold. When the peak pressure difference is too low, it indicates that the current pressing intensity is insufficient. The pressing pressure rise rate is increased to enhance the compaction capacity of the mud cake. When the peak pressure difference is too high, the pressure rise rate is reduced to avoid mud cake cracking or abnormal filtrate discharge due to excessive local pressure, thereby improving the overall stability of the mud cake.

[0050] After pressing, based on the filtrate discharge per unit time and the pressure difference established on the filter plates, combined with the dry basis load of the current batch, the cake accumulation state inside the filter chamber is calculated in reverse to obtain the corresponding estimated cake thickness. Since the feed rate, sludge organic matter content, and filtration conditions all affect cake thickness, this inverse calculation method can accurately reflect the actual cake formation. The study found that when the cake thickness in the central area of ​​the feed end is relatively large, the problem of locally high moisture content is more likely to occur.

[0051] The above correction results are correlated using a unified parameter model to form cake forming control parameters applicable to the current batch of sludge, which are then used for subsequent thermal vacuum synergistic dewatering control. These cake forming parameters comprehensively reflect the cake thickness, compaction degree, particle stability, and dewatering adaptability of the current batch of sludge, thereby improving the heat transfer uniformity and moisture vaporization efficiency during the subsequent low-temperature vacuum drying stage.

[0052] Furthermore, based on the batch cake forming parameters, low-temperature heating parameters, and vacuum maintenance parameters, thermal vacuum coordinated dehydration control is performed to obtain batch drying process data, including: The cake thickness control range in the filter chamber is determined based on the batch cake forming parameters. Within the cake thickness control range, the hot water circulation unit is controlled to supply heat to the filter plate according to the low-temperature heating parameters, and the filter plate inlet water temperature, filter plate return water temperature, and hot water circulation flow rate are obtained to calculate the batch heat supply. The vacuum unit is controlled to reduce the drying chamber pressure according to the vacuum maintenance parameters, and the chamber vacuum pressure, vacuum pump operating frequency, and condensate discharge are obtained to calculate the batch moisture vaporization. The batch heat supply, batch moisture vaporization, and chamber vacuum pressure are correlated according to the same batch time axis to form the batch drying process data.

[0053] Based on the estimated cake thickness, pressing and holding conditions, and feed load in the batch cake forming parameters, a suitable cake thickness control range for the current batch of sludge was determined to avoid uneven internal heat transfer and difficulty in moisture vaporization and discharge caused by excessively thick cakes. Simultaneously, considering the cake forming state in different filter plate areas, the cake thickness at the feed end and in the middle area was coordinated and controlled to improve the overall uniformity of the subsequent hot vacuum dewatering stage. The study found that when the cake thickness near the central feed hole is larger, localized high moisture content is more likely to occur.

[0054] Hot water is continuously supplied to the filter plates via a hot water circulation pump, maintaining a stable low-temperature heating state. A temperature detection device continuously monitors the inlet and outlet water temperatures and hot water circulation flow rate, calculating the heat supply for the current batch of sludge based on the heat exchange. Under low-temperature vacuum conditions, the water in the sludge can vaporize and separate at lower temperatures, thus reducing overall energy consumption. Engineering operation data shows that sludge water vaporization and removal are typically achieved at approximately 50°C.

[0055] The vacuum pump is activated to continuously reduce the internal pressure of the drying chamber, lowering the boiling point of the water inside the sludge and causing it to vaporize rapidly under negative pressure. The vaporized water vapor is then cooled by a condenser to form condensate before being discharged from the system. During operation, the vacuum pressure, vacuum pump operating frequency, and condensate discharge volume are collected in real time. Based on the changes in condensate volume, the amount of water vaporized in the current batch of sludge is calculated to reflect the current dewatering and drying capacity.

[0056] Heating data acquired during the hot water circulation stage, moisture vaporization data acquired during the vacuum dehydration stage, and vacuum pressure data inside the chamber are correlated and integrated according to a unified time series to form drying process data corresponding to the current batch of sludge. This drying process data reflects the heat transfer state, moisture migration state, and vacuum dehydration state of the sludge during the combined thermal and vacuum dehydration process, providing a data foundation for subsequent identification of dehydration rate decay and determination of drying termination.

[0057] Furthermore, based on the batch drying process data, the dehydration rate decay is identified, and a drying termination determination result is generated, including: The amount of water removed per unit time is calculated based on the batch drying process data; the rate of decrease in dehydration is calculated based on the amount of water removed per unit time within multiple consecutive time windows; when the rate of decrease in dehydration is greater than a preset rate of decrease threshold and the amount of water removed per unit time is less than a preset amount of water removed threshold, a first drying termination determination result is generated; when the rate of decrease in dehydration is less than or equal to the preset rate of decrease threshold and the drying load level corresponding to the current batch is a high load level, the vacuum holding time is extended and the amount of water removed per unit time is recalculated; when the amount of water removed per unit time after extending the vacuum holding time is still less than the preset amount of water removed threshold, a second drying termination determination result is generated; based on the first drying termination determination result or the second drying termination determination result, the thermal vacuum coordinated dehydration control of the current batch is stopped.

[0058] During the thermal vacuum synergistic dehydration process, data such as condensate discharge, vacuum pressure, hot water circulation status, and operating time are collected in real time. The amount of water removed within each preset time interval is calculated to obtain the dehydration rate per unit time, which characterizes the real-time dehydration capacity of the current batch of sludge under low-temperature vacuum conditions. Since the moisture content in the sludge gradually decreases during the drying process, the dehydration rate per unit time will show a gradual downward trend.

[0059] The dewatering volume per unit time was compared and analyzed within a continuous time window for different time periods, and the decreasing trend of dewatering volume over time was calculated to obtain the slope of the dewatering rate decrease. When the dewatering rate decreases significantly, it indicates that the easily removable water inside the sludge has basically completed vaporization and discharge, and the sludge is gradually entering the final stage of dewatering.

[0060] When the dewatering capacity per unit time is continuously reduced and the amount of dewatering in the current time period is lower than the minimum effective dewatering threshold, it is determined that the current batch of sludge has basically reached the target drying state. At this time, the first drying termination judgment result is generated to trigger subsequent shutdown control to avoid energy waste caused by continued operation.

[0061] When the current batch is identified as operating under high load, due to the high organic matter content of the sludge or the large thickness of the sludge cake, some bound water may still not be fully removed. Therefore, if the dewatering rate has not yet decreased significantly, the vacuum holding time is extended, and the amount of water dewatered per unit time during the extended period is recalculated to further improve the final drying effect. Studies have shown that the efficiency of low-temperature vacuum dewatering under high organic matter sludge conditions will decrease significantly, thus requiring an appropriate extension of the vacuum dewatering time.

[0062] After the extended vacuum holding phase ends, it is determined again whether the current dewatering amount per unit time is still lower than the effective dewatering threshold. If effective dewatering still cannot be achieved, it indicates that the current batch of sludge has reached a stable drying state, and a second drying termination judgment result is generated.

[0063] Upon receiving any drying termination determination result, the hot water circulation heating and vacuum suction operation are stopped, and the low-temperature vacuum dewatering and drying process of the current batch of sludge is ended. Then, the unloading and preparation stage for the next batch of operation is entered, thereby realizing adaptive termination control based on the change of dewatering rate.

[0064] Furthermore, based on the moisture content distribution of the mud cake after unloading, the corrected parameters for the next batch of operations are generated, including: The moisture content of the unloaded mud cake is measured on the feed end filter plate, intermediate filter plate, and end filter plate. The moisture content measurements include those near the central mud inlet and those near the edge of each filter plate. The moisture content deviation at the center and edge is calculated based on these measurements. The initial feed flow rate correction and pressing hold time correction for the next batch are generated based on the deviation of the moisture content measurement near the central mud inlet in the feed end filter plate from the target moisture content. The thickness limit correction and vacuum hold time correction for the next batch are generated based on the deviation of the moisture content deviation at the center and edge from a preset distribution deviation threshold. The thermal vacuum co-dehydration time correction is generated based on the comparison of the moisture content measurements at each location with the target moisture content and the dehydration rate decrease slope. The initial feed flow rate correction, pressing hold time correction, mud cake thickness limit correction, vacuum hold time correction, and thermal vacuum co-dehydration time correction for the next batch are integrated to form the operating correction parameters for the next batch.

[0065] After the current batch of sludge underwent low-temperature vacuum dewatering and drying and was unloaded, samples of the sludge cake from different filter plate areas were taken and tested. Moisture content data for the sludge cake at the feed end, middle position, and end position were obtained. Simultaneously, the moisture content of the sludge cake near the central inlet hole and the filter plate edge was measured to analyze the dewatering uniformity at different locations. The results show that the central area at the feed end is more prone to localized high moisture content due to the greater thickness of the sludge cake; therefore, the dewatering status in this area needs to be closely monitored.

[0066] The moisture content data of the central and edge regions of each filter plate were statistically analyzed, and the difference between the two was calculated to characterize the uniformity of dewatering within the sludge cake. When the moisture content of the central region is significantly higher than that of the edge region, it indicates that the sludge cake thickness distribution is uneven or that internal heat transfer is insufficient; when the difference in moisture content between the center and the edge is small, it indicates that the overall drying state of the current batch of sludge is relatively uniform.

[0067] The actual moisture content of the central area of ​​the feed end is compared with the target moisture content of the cake. When the moisture content of this area is higher than the target value, it indicates that there is a problem of excessive local mud feeding or insufficient cake compaction in the current batch. Therefore, in the next batch, the initial feed flow rate is reduced and the pressing holding time is appropriately extended to reduce the cake thickness and improve the filter pressing effect. When the actual moisture content is close to the target value, the current operating parameters are maintained.

[0068] When the difference in moisture content between the central and peripheral areas exceeds the preset threshold, it indicates that there is a significant problem of uneven dehydration inside the sludge cake. Accordingly, the thickness of the sludge cake allowed to be formed in the next batch should be reduced, and the vacuum holding time should be extended to enhance the ability of water migration and vaporization removal inside the sludge. When the moisture content deviation between the center and the edge is small, it indicates that the drying uniformity inside the sludge cake is good and the current operating state can be maintained.

[0069] By comprehensively analyzing the final moisture content of each filter plate area and the decay trend of the current batch dewatering rate, when the sludge still has a high moisture content in the later stage of drying and the dewatering rate decreases slowly, it indicates that the current thermal vacuum co-dewatering time is insufficient. Therefore, the thermal vacuum co-dewatering time of the next batch should be appropriately extended. When the moisture content is close to the target value and the dewatering rate decreases significantly, the subsequent running time should be shortened to reduce system energy consumption.

[0070] The various correction results generated after the current batch of sludge is unloaded are integrated and processed according to a unified control logic to generate control parameters applicable to the operating status of the next batch of sludge. These parameters are then used for subsequent batches of sludge feeding control, pressing control, and thermal vacuum synergistic dewatering control, thereby forming a closed-loop adaptive adjustment mechanism based on historical operating results. This improves the operational stability of the low-temperature vacuum dewatering and drying system and the accuracy of sludge cake moisture content control.

[0071] Example 2, based on the same inventive concept as the sludge low-temperature vacuum dewatering and drying control method in the foregoing examples, such as... Figure 2 As shown in the figure, this application provides a sludge low-temperature vacuum dewatering and drying control system, the system comprising: The system comprises the following modules: a state characterization module 10, used to characterize the pretreatment state of the sludge to be treated and obtain a batch sludge infeed state dataset; a load classification module 20, used to classify the batch drying load based on the batch sludge infeed state dataset, obtain the drying load level, and configure basic operating parameters, including sludge infeed control parameters, pressing control parameters, low-temperature heating parameters, and vacuum maintenance parameters; a sludge infeed control module 30, used to control the batch sludge infeed according to the sludge infeed control parameters and generate solids retention evaluation results based on the filtrate discharge state and filter plate pressure difference state during the sludge infeed process; a parameter correction module 40, used to correct the pressing control parameters based on the solids retention evaluation results and obtain batch cake forming parameters; a dewatering control module 50, used to perform thermal vacuum coordinated dewatering control based on the batch cake forming parameters, low-temperature heating parameters, and vacuum maintenance parameters to obtain batch drying process data; and an attenuation identification module 60, used to identify the dewatering rate attenuation based on the batch drying process data, generate a drying termination judgment result, and generate the next batch operation correction parameters based on the cake moisture content distribution after unloading.

[0072] Furthermore, the state representation module 10 is used to perform the following operation steps: The following steps are taken: First, obtain the influent sludge moisture content, effluent sludge moisture content, and throughput per unit time of the sludge pretreatment unit, and calculate the pretreatment dewatering contribution. Second, obtain the sludge concentration, thickening influent flow rate, and flocculant dosage ratio of the mechanical thickening unit, and calculate the thickening stability coefficient. Third, obtain the coagulant dosage ratio, flocculant compensation dosage ratio, conditioning retention time, and post-conditioning sludge rheological parameters of the sludge conditioning unit, and calculate the conditioning fit coefficient. Fourth, obtain the organic matter ratio and batch influent volume of the sludge to be treated, and combine these with the pretreatment dewatering contribution, thickening stability coefficient, and conditioning fit coefficient, associating them according to batch number to form the batch influent status dataset.

[0073] Furthermore, the load classification module 20 is used to perform the following operation steps: The dry basis load of the current batch is calculated based on the sludge concentration, sludge moisture content, and batch sludge intake. A drying load feature vector is constructed based on the dry basis load, organic matter ratio, pretreatment dewatering contribution, concentration stability coefficient, and conditioning adaptation coefficient. The similarity of the drying load feature vector with preset low load samples, preset medium load samples, and preset high load samples is calculated to obtain multiple load similarities. The load sample category corresponding to the maximum load similarity is selected as the drying load level. The drying load level is identified by sludge intake limit, sludge cake thickness limit, heating intensity limit, and vacuum retention limit.

[0074] Furthermore, the load classification module 20 is used to perform the following operation steps: When the drying load level is low, a first sludge inlet flow rate, a first pressing hold time, a first hot water circulation flow rate, and a first vacuum hold time are configured; when the drying load level is medium, a second sludge inlet flow rate, a second pressing hold time, a second hot water circulation flow rate, and a second vacuum hold time are configured; when the drying load level is high, a third sludge inlet flow rate, a third pressing hold time, a third hot water circulation flow rate, and a third vacuum hold time are configured; wherein, the third sludge inlet flow rate is less than the second sludge inlet flow rate, the second sludge inlet flow rate is less than the first sludge inlet flow rate, the third vacuum hold time is greater than the second vacuum hold time, and the second vacuum hold time is greater than the first vacuum hold time.

[0075] Furthermore, the mud feeding control module 30 is used to perform the following operation steps: The batch sludge feeding process is divided into an initial filling stage, a differential pressure establishment stage, and a sludge feeding termination stage according to the sludge inlet flow rate. The filtrate suspended solids concentration, filtrate discharge rate, filter plate differential pressure change rate, and filter plate differential pressure peak value are obtained for each of the three stages. The batch filtrate solids loss is calculated based on the filtrate suspended solids concentration and filtrate discharge rate at each stage. The solids retention deviation is calculated based on the ratio of the batch filtrate solids loss to the dry basis load. The solids retention evaluation result is generated based on the solids retention deviation, the filter plate differential pressure change rate, and the filter plate differential pressure peak value.

[0076] Furthermore, the parameter correction module 40 is used to perform the following operation steps: Based on the deviation of the solid retention deviation from the preset retention deviation threshold, a sludge flow constraint correction and a flocculant compensation correction are generated; based on the deviation of the filter plate pressure difference change rate from the preset pressure difference change rate threshold, a pressing hold time correction is generated; based on the deviation of the filter plate pressure difference peak value from the preset pressure difference threshold, a pressing pressure rise correction is generated; based on the filtrate discharge at the end of pressing, the filter plate pressure difference, and the dry basis load, the cake thickness is back-calculated to obtain an estimated cake thickness; the estimated cake thickness, the sludge flow constraint correction, the flocculant compensation correction, the pressing hold time correction, and the pressing pressure rise correction are fused to generate the batch cake forming parameters.

[0077] Furthermore, the dehydration control module 50 is used to perform the following operation steps: The cake thickness control range in the filter chamber is determined based on the batch cake forming parameters. Within the cake thickness control range, the hot water circulation unit is controlled to supply heat to the filter plate according to the low-temperature heating parameters, and the filter plate inlet water temperature, filter plate return water temperature, and hot water circulation flow rate are obtained to calculate the batch heat supply. The vacuum unit is controlled to reduce the drying chamber pressure according to the vacuum maintenance parameters, and the chamber vacuum pressure, vacuum pump operating frequency, and condensate discharge are obtained to calculate the batch moisture vaporization. The batch heat supply, batch moisture vaporization, and chamber vacuum pressure are correlated according to the same batch time axis to form the batch drying process data.

[0078] Furthermore, the attenuation recognition module 60 is used to perform the following operation steps: The amount of water removed per unit time is calculated based on the batch drying process data; the rate of decrease in dehydration is calculated based on the amount of water removed per unit time within multiple consecutive time windows; when the rate of decrease in dehydration is greater than a preset rate of decrease threshold and the amount of water removed per unit time is less than a preset amount of water removed threshold, a first drying termination determination result is generated; when the rate of decrease in dehydration is less than or equal to the preset rate of decrease threshold and the drying load level corresponding to the current batch is a high load level, the vacuum holding time is extended and the amount of water removed per unit time is recalculated; when the amount of water removed per unit time after extending the vacuum holding time is still less than the preset amount of water removed threshold, a second drying termination determination result is generated; based on the first drying termination determination result or the second drying termination determination result, the thermal vacuum coordinated dehydration control of the current batch is stopped.

[0079] Furthermore, the attenuation recognition module 60 is used to perform the following operation steps: The moisture content of the unloaded mud cake is measured on the feed end filter plate, intermediate filter plate, and end filter plate. The moisture content measurements include those near the central mud inlet and those near the edge of each filter plate. The moisture content deviation at the center and edge is calculated based on these measurements. The initial feed flow rate correction and pressing hold time correction for the next batch are generated based on the deviation of the moisture content measurement near the central mud inlet in the feed end filter plate from the target moisture content. The thickness limit correction and vacuum hold time correction for the next batch are generated based on the deviation of the moisture content deviation at the center and edge from a preset distribution deviation threshold. The thermal vacuum co-dehydration time correction is generated based on the comparison of the moisture content measurements at each location with the target moisture content and the dehydration rate decrease slope. The initial feed flow rate correction, pressing hold time correction, mud cake thickness limit correction, vacuum hold time correction, and thermal vacuum co-dehydration time correction for the next batch are integrated to form the operating correction parameters for the next batch.

[0080] Through the foregoing detailed description of a sludge low-temperature vacuum dewatering and drying control method, those skilled in the art can clearly understand the sludge low-temperature vacuum dewatering and drying control system in this embodiment. Since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and relevant parts can be referred to in the method section.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for controlling low-temperature vacuum dewatering and drying of sludge, characterized in that, The method includes: The pretreatment state of the sludge to be treated was characterized to obtain a batch sludge infeed state dataset. Based on the batch mud feeding status dataset, batch drying load is classified to obtain drying load level, and basic operating parameters are configured, including mud feeding control parameters, pressing control parameters, low temperature heating parameters and vacuum maintenance parameters. Batch sludge feeding control is performed according to the sludge feeding control parameters, and solids retention evaluation results are generated based on the filtrate discharge status and filter plate pressure difference status during the sludge feeding process. The pressing control parameters are corrected based on the solids retention evaluation results to obtain batch cake forming parameters; Based on the batch cake forming parameters, low-temperature heating parameters, and vacuum maintenance parameters, thermal vacuum synergistic dehydration control is performed to obtain batch drying process data. Based on the batch drying process data, the dehydration rate decay is identified, a drying termination determination result is generated, and the next batch operation correction parameters are generated based on the moisture content distribution of the mud cake after unloading.

2. The method for controlling low-temperature vacuum dewatering and drying of sludge as described in claim 1, characterized in that, The pretreatment state of the sludge to be treated is characterized to obtain a batch sludge infeed state dataset, including: Obtain the influent sludge moisture content, effluent sludge moisture content, and treatment capacity per unit time of the sludge pretreatment unit, and calculate the contribution of pretreatment to dewatering. Obtain the sludge concentration, sludge inflow rate, and flocculant dosage ratio of the mechanical thickening unit, and calculate the thickening stability coefficient; Obtain the coagulant dosage ratio, flocculant compensation dosage ratio, conditioning retention time, and post-conditioning sludge rheological parameters of the sludge conditioning unit, and calculate the conditioning fit coefficient; The organic matter ratio and batch sludge input of the sludge to be treated are obtained. Combined with the pretreatment dewatering contribution, concentration stability coefficient, and conditioning adaptation coefficient, the data are associated according to the batch number to form the batch sludge input status dataset.

3. The method for controlling low-temperature vacuum dewatering and drying of sludge as described in claim 2, characterized in that, Based on the batch sludge inlet status dataset, batch drying load classification is performed to obtain drying load levels, including: The dry basis load of the current batch is calculated based on the sludge concentration, sludge moisture content, and batch sludge intake. A dry load feature vector is constructed based on the dry load, organic matter ratio, pretreatment dehydration contribution, concentration stability coefficient, and conditioning adaptation coefficient. The similarity of the drying load feature vector with preset low load samples, preset medium load samples and preset high load samples is calculated to obtain multiple load similarities; The load sample category corresponding to the maximum load similarity is selected as the drying load level. The drying load level is identified by the limits on the amount of mud fed, the thickness of the mud cake, the heating intensity, and the vacuum retention.

4. The method for controlling low-temperature vacuum dewatering and drying of sludge as described in claim 3, characterized in that, Configure basic operating parameters, including: When the drying load level is a low load level, the first mud inlet flow rate, the first pressing holding time, the first hot water circulation flow rate, and the first vacuum holding time are configured. When the drying load level is medium load level, the second mud inlet flow rate, the second pressing holding time, the second hot water circulation flow rate, and the second vacuum holding time are configured. When the drying load level is a high load level, the third mud inlet flow rate, the third pressing holding time, the third hot water circulation flow rate, and the third vacuum holding time are configured. Wherein, the third sludge flow rate is less than the second sludge flow rate, the second sludge flow rate is less than the first sludge flow rate, the third vacuum holding time is greater than the second vacuum holding time, and the second vacuum holding time is greater than the first vacuum holding time.

5. The method for controlling low-temperature vacuum dewatering and drying of sludge as described in claim 3, characterized in that, Solids retention evaluation results are generated based on the filtrate discharge status and filter plate pressure difference status during the sludge feeding process, including: The batch slurry feeding process is divided into the initial filling stage, the differential pressure establishment stage, and the slurry feeding end stage according to the slurry flow rate. The concentration of suspended solids in the filtrate, the discharge rate of the filtrate, the rate of change of the differential pressure on the filter plate, and the peak value of the differential pressure on the filter plate were obtained respectively in the initial filling section, the differential pressure establishment section, and the sludge inlet termination section. The batch filtrate solids loss is calculated based on the filtrate suspended solids concentration and filtrate discharge volume at each stage. The solids retention deviation is calculated based on the ratio of the batch filtrate solids loss to the dry basis load. The solid retention evaluation result is generated based on the solid retention deviation, the filter plate pressure difference change rate, and the filter plate pressure difference peak value.

6. The method for controlling low-temperature vacuum dewatering and drying of sludge as described in claim 5, characterized in that, Based on the solids retention evaluation results, the pressing control parameters are corrected to obtain batch cake forming parameters, including: Based on the deviation of the solid retention deviation from the preset retention deviation threshold, a sludge flow constraint correction amount and a flocculant compensation correction amount are generated. Based on the deviation of the filter plate pressure difference change rate from the preset pressure difference change rate threshold, a pressing hold time correction amount is generated; Based on the deviation between the peak pressure difference of the filter plate and the preset pressure difference threshold, a pressing pressure rise correction amount is generated; The cake thickness is back-calculated based on the filtrate discharge, filter plate pressure difference, and dry basis load at the end of pressing to obtain an estimated cake thickness. The parameters of the batch mud cake forming parameters are generated by fusing the estimated mud cake thickness, the mud flow rate constraint correction, the flocculant compensation correction, the pressing holding time correction, and the pressing pressure rise correction.

7. The method for controlling low-temperature vacuum dewatering and drying of sludge as described in claim 1, characterized in that, Based on the batch cake forming parameters, low-temperature heating parameters, and vacuum maintenance parameters, thermal-vacuum coordinated dehydration control is performed to obtain batch drying process data, including: The thickness control range of the filter cake in the filter chamber is determined based on the batch cake forming parameters. Within the specified mud cake thickness control range, the hot water circulation unit is controlled to supply heat to the filter plate according to the specified low-temperature heating parameters, and the filter plate inlet water temperature, filter plate return water temperature and hot water circulation flow rate are obtained to calculate the batch heat supply. The vacuum unit is controlled to reduce the pressure in the drying chamber according to the vacuum maintenance parameters, and the chamber vacuum pressure, vacuum pump operating frequency and condensate discharge amount are obtained to calculate the batch moisture vaporization amount. The batch drying process data is generated by associating the batch heat supply, batch moisture vaporization amount, and chamber vacuum pressure with the same batch time axis.

8. The method for controlling low-temperature vacuum dewatering and drying of sludge as described in claim 1, characterized in that, Based on the batch drying process data, the dehydration rate decay is identified, and a drying termination determination result is generated, including: Calculate the amount of water removed per unit time based on the batch drying process data; The slope of the dehydration rate decrease is calculated based on the amount of water removed per unit time within multiple consecutive time windows. When the rate of decrease of the dehydration rate is greater than a preset rate of decrease threshold and the amount of water dehydrated per unit time is less than a preset amount of water dehydrated threshold, a first drying termination determination result is generated. When the dehydration rate decreases at a rate less than or equal to a preset decrease rate threshold, and the current batch corresponds to a high drying load level, the vacuum holding time is extended and the dehydration amount per unit time is recalculated. When the amount of water removed per unit time after extending the vacuum holding time is still less than the preset water removal threshold, a second drying termination judgment result is generated. Based on the first or second drying termination determination result, stop the thermal vacuum synergistic dehydration control for the current batch.

9. The method for controlling low-temperature vacuum dewatering and drying of sludge as described in claim 8, characterized in that, Based on the moisture content distribution of the mud cake after unloading, the following operational correction parameters are generated for the next batch of operations: The moisture content of the mud cake after unloading is measured on the feed end filter plate, the middle filter plate and the end filter plate. The moisture content measurement value includes the moisture content measurement value of the area near the central mud inlet hole and the area near the edge of the filter plate in each filter plate. Calculate the moisture content deviation at the center edge based on the moisture content detection value; Based on the deviation between the moisture content detection value in the area near the central mud inlet hole in the feed end filter plate and the target moisture content, the initial feed flow correction amount and the pressing holding time correction amount for the next batch are generated. Based on the deviation of the moisture content deviation at the center edge from the preset distribution deviation threshold, the correction amount for the thickness limit of the next batch of mud cake and the correction amount for the vacuum holding time are generated. Based on the comparison results between the moisture content detection values ​​at each detection location and the target moisture content, as well as the slope of the dehydration rate decrease, a thermal vacuum synergistic dehydration time correction amount is generated. The correction parameters for the next batch of operation are formed by integrating the corrections for the initial feed flow rate, pressing holding time, cake thickness limit, vacuum holding time, and thermal vacuum co-dehydration time.

10. A sludge low-temperature vacuum dewatering and drying control system, characterized in that, For implementing the sludge low-temperature vacuum dewatering and drying control method according to any one of claims 1-9, the system comprises: The state characterization module is used to characterize the state of the sludge before it is fed into the system and obtain a batch sludge feeding state dataset. The load classification module is used to classify the batch drying load based on the batch mud feeding status dataset, obtain the drying load level, and configure basic operating parameters, including mud feeding control parameters, pressing control parameters, low temperature heating parameters, and vacuum maintenance parameters. The sludge feeding control module is used to control the batch sludge feeding according to the sludge feeding control parameters, and to generate solid retention evaluation results based on the filtrate discharge status and filter plate pressure difference status during the sludge feeding process. The parameter correction module is used to correct the pressing control parameters based on the solids retention evaluation results to obtain batch cake forming parameters. The dehydration control module is used to perform thermal vacuum coordinated dehydration control based on the batch cake forming parameters, low temperature heating parameters and vacuum maintenance parameters to obtain batch drying process data. The attenuation identification module is used to identify the attenuation of the dehydration rate based on the batch drying process data, generate a drying termination determination result, and generate the next batch operation correction parameters based on the moisture content distribution of the mud cake after unloading.

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