Kitchen waste anaerobic biogas residue resource utilization method and system

Abstract

The invention relates to the technical field of waste resource utilization, in particular to a kitchen waste anaerobic biogas residue resource utilization method and system.The kitchen waste anaerobic biogas residue resource utilization method comprises the steps that the fan rotating speed and the pipe network static pressure of the speed increasing stage, the constant speed stage and the speed reducing stage are obtained; according to the change rate of the pipe network static pressure along with the fan rotating speed in the speed increasing stage, a compression hardening factor is obtained by combining the difference condition of the corresponding change rates in different fan rotating speed states; the viscoelastic hysteretic damage degree is obtained according to the difference of the average change rate of the pipe network static pressure along with the fan rotating speed in the speed increasing stage and the speed reducing stage; determining a pore structure characteristic value based on the change rate of the pipe network static pressure along with time in the constant speed stage; according to the compression hardening factor, the viscoelastic hysteretic damage degree and the pore structure characteristic value, the rheological state of the kitchen biogas residues is judged, and the safety boundary of the fan rotating speed of the air blower is set. According to the invention, the problem of excessive material compaction or pipe network drainage failure caused by misjudgment of a high-resistance working condition in traditional control is fundamentally solved.

Description

A method and system for the resource utilization of anaerobic digestate from kitchen waste Technical Field

[0001] This invention relates to the field of waste resource utilization technology, specifically to a method and system for the resource utilization of anaerobic digestate residue from kitchen waste. Background Technology

[0002] The biogas residue produced after anaerobic digestion of food waste is characterized by high water content and rich in extracellular polymeric substances (EPS). EPS is a viscous substance secreted by microorganisms, making the biogas residue a typical viscoelastic non-Newtonian fluid, which has both "viscous" (irreversible deformation after being subjected to force) and "elastic" (partially able to rebound). The pores inside the residue are the core channels for ventilation, oxygen supply and moisture removal. However, this pore structure is extremely sensitive to aerodynamic stress (wind pressure), and will irreversibly close if the critical value is exceeded.

[0003] The resource utilization of biogas residue (such as making organic fertilizer and fuel) requires first reducing the moisture content through aerobic biological drying. The core of drying is forced ventilation. The intensity of ventilation (air volume and air pressure) is directly determined by the fan speed. The higher the speed, the greater the air volume and air pressure, and the higher the oxygen supply and moisture dissipation efficiency.

[0004] Traditional wind speed control methods, employing constant airflow or simple pressure feedback, fail to consider the viscoelastic properties of biogas residue and cannot distinguish the causes of high resistance. Increased ventilation resistance may be due to biogas residue compaction (caused by viscoelasticity) or external pipe network blockage (physical factors). If compaction is misinterpreted as blockage and the rotation speed (wind pressure) is increased, the biogas residue pores will be further compressed, resulting in loss of air permeability. Conversely, if blockage is misinterpreted as compaction and the rotation speed (wind pressure) is decreased, water accumulation will prevent drainage. Therefore, existing methods for controlling the drying and ventilation of biogas residue produced after anaerobic digestion of food waste cannot distinguish the causes of high resistance, leading to poorly rational wind speed settings. Summary of the Invention

[0005] To address the technical problem that existing wind speed control methods cannot distinguish the causes of high resistance, resulting in poor wind speed setting rationality, the present invention aims to provide a method and system for the resource utilization of anaerobic digester residue from food waste. The specific technical solution adopted is as follows: Firstly, the present invention provides a method for the resource utilization of anaerobic digester residue from food waste, comprising: acquiring the blower speed and pipeline static pressure at the same moment during the blower's acceleration, constant speed, and deceleration phases; obtaining a compressibility hardening factor based on the rate of change of pipeline static pressure with blower speed during the acceleration phase, combined with the differences in the corresponding rates of change under different blower speed states; obtaining the degree of viscoelastic hysteresis damage based on the difference in the average rate of change of pipeline static pressure with blower speed during the acceleration and deceleration phases; determining the pore structure characteristic value based on the rate of change of pipeline static pressure with time during the constant speed phase; judging the rheological state of the food waste digester residue based on the compressibility hardening factor, the degree of viscoelastic hysteresis damage, and the pore structure characteristic value; and setting a safety boundary for the blower speed based on the rheological state of the food waste digester residue.

[0006] Preferably, the step of obtaining the compression hardening factor based on the rate of change of the pipeline static pressure with the fan speed during the acceleration phase, combined with the differences in the rate of change corresponding to different fan speed states, specifically includes: obtaining the stiffness coefficient at each moment of the acceleration phase based on the changes in pipeline static pressure and fan speed within a preset local time window at each moment of the acceleration phase; using the ratio of the stiffness coefficient to the fan speed at each moment of the acceleration phase as the aerodynamic drag coefficient at each moment of the acceleration phase; and obtaining the compression hardening factor based on the proportion of the difference between the aerodynamic drag coefficient at the moment corresponding to high fan speed and the moment corresponding to low fan speed during the acceleration phase.

[0007] Preferably, the step of obtaining the stiffness coefficient at each moment of the acceleration phase based on the changes in pipeline static pressure and fan speed within a preset local time window at each moment of the acceleration phase specifically includes: for any moment in the acceleration phase, performing linear fitting with the fan speed at each moment within the local time window at that moment as the abscissa and the pipeline static pressure at the same moment as the ordinate, and using the slope of the fitted line as the stiffness coefficient at that moment.

[0008] Preferably, the step of obtaining the compression hardening factor based on the ratio of the difference between the aerodynamic drag coefficient at the high fan speed and the low fan speed during the acceleration phase specifically includes: obtaining the average value of the aerodynamic drag coefficient at a predetermined number of moments in the chronological order of the acceleration phase as the low-pressure drag coefficient; obtaining the average value of the aerodynamic drag coefficient at a predetermined number of moments in the reverse chronological order of the acceleration phase as the high-pressure drag coefficient; and using the ratio of the difference between the high-pressure drag coefficient and the low-pressure drag coefficient to the low-pressure drag coefficient as the compression hardening factor.

[0009] Preferably, the step of obtaining the degree of viscoelastic hysteresis damage based on the difference in the average rate of change of the static pressure of the pipeline network with the fan speed during the acceleration and deceleration stages specifically includes: obtaining the stiffness coefficient at each moment during the deceleration stage; and determining the degree of viscoelastic hysteresis damage based on the difference between the mean stiffness coefficient at all moments during the acceleration stage and the mean stiffness coefficient at all moments during the deceleration stage.

[0010] Preferably, determining the pore structure characteristic value based on the rate of change of pipeline static pressure over time during the constant-speed stage specifically includes: performing linear fitting with each moment in the constant-speed stage as the abscissa and the pipeline static pressure at the same moment as the ordinate, and using the slope of the fitted line as the pore structure characteristic value.

[0011] Preferably, determining the rheological state of the kitchen waste biogas residue based on the compression hardening factor, viscoelastic hysteresis damage degree, and pore structure characteristic value specifically includes: determining that the kitchen waste biogas residue is in an organic material compaction state when the compression hardening factor, viscoelastic hysteresis damage degree, and pore structure characteristic value meet a first threshold condition; determining that the kitchen waste biogas residue is in a pipeline blockage state when the compression hardening factor, viscoelastic hysteresis damage degree, and pore structure characteristic value meet a third threshold condition; determining that the kitchen waste biogas residue is in a normal aeration state when the compression hardening factor, viscoelastic hysteresis damage degree, and pore structure characteristic value meet a third threshold condition; the first threshold condition is that the compression hardening factor is greater than a preset hardening threshold, and the viscoelastic hysteresis damage degree is greater than a preset loss threshold; the second threshold condition is that the compression hardening factor is greater than a preset hardening threshold or the pore structure characteristic value is greater than a preset drift threshold, and the viscoelastic hysteresis damage degree is less than or equal to a preset loss threshold; the third threshold condition is that neither the first threshold condition nor the second threshold condition is met.

[0012] Preferably, setting the safety boundary of the blower speed based on the rheological state of the kitchen waste biogas residue specifically includes: obtaining a preset reference speed of the blower; for the compacted state of organic materials, using the product of the reference speed and a preset attenuation coefficient as the speed safety boundary; for the blocked state of the pipeline network, using the rated speed of the blower as the speed safety boundary; for the normal ventilation state, using the product of the reference speed and a preset gain coefficient as the speed safety boundary; wherein the attenuation coefficient is less than the gain coefficient.

[0013] Preferably, a pulse purging action is set when the pipeline is blocked.

[0014] Secondly, this invention provides a system for the resource utilization of anaerobic digestate from food waste. This system is used to implement a method for the resource utilization of anaerobic digestate from food waste. The system includes: a data acquisition module for acquiring the blower speed and pipeline static pressure at the same moment during the blower's acceleration, constant speed, and deceleration phases; a detection and testing module for obtaining a compressibility hardening factor based on the rate of change of pipeline static pressure with blower speed during the acceleration phase, combined with the differences in the corresponding rates of change under different blower speed states; obtaining the degree of viscoelastic hysteresis damage based on the difference in the average rate of change of pipeline static pressure with blower speed during the acceleration and deceleration phases; determining pore structure characteristic values ​​based on the rate of change of pipeline static pressure with time during the constant speed phase; judging the rheological state of the food waste digestate based on the compressibility hardening factor, the degree of viscoelastic hysteresis damage, and the pore structure characteristic values; and a routine operation module for setting a safety boundary for the blower speed based on the rheological state of the food waste digestate.

[0015] The embodiments of this invention have at least the following beneficial effects: Firstly, based on the differences in the mechanical response of the stack body under different aerodynamic load stages, this invention decouples the physical causes of ventilation resistance and extracts characteristic parameters in three dimensions to provide a scientific basis for subsequent rheological state determination. In the acceleration stage, stress is applied by gradually increasing the fan speed, stimulating the compression hardening characteristics of the stack material, corresponding to the nonlinear densification characteristics of compaction. In the constant speed stage, high stress is maintained by keeping the fan speed constant to observe the slow collapse characteristics of the stack material, corresponding to the long-term instability characteristics of compaction. In the deceleration stage, stress is released by gradually decreasing the fan speed to observe the rebound hysteresis characteristics of the stack material, corresponding to the viscous energy dissipation characteristics of compaction. Analyzing the three different speed stages allows for the temporal separation of different rheological characteristics. Furthermore, the decoupled micro-rheological characteristics are transformed into macro-engineering control strategies. By accurately determining the rheological state of the kitchen waste residue and matching an appropriate fan speed safety boundary, the problem of over-compaction of materials or failure of pipeline drainage caused by misjudgment under high-resistance conditions in traditional control is fundamentally solved. Attached Figure Description

[0016] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 is a flowchart of the steps of a method for the resource utilization of anaerobic digestate of kitchen waste provided by the present invention; Figure 2 is a flowchart of the steps of a method for obtaining compression hardening factor provided by the present invention. Detailed Implementation

[0018] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation methods, structures, features, and effects of a method and system for the resource utilization of anaerobic digester residue from kitchen waste according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0020] The following describes in detail, with reference to the accompanying drawings, a specific scheme for the resource utilization method and system of anaerobic digester residue for kitchen waste provided by the present invention. First, it should be noted that, to ensure the calculation results are meaningful, in the embodiments of this application, when performing fractional operations, if the denominator is 0, a parameter adjustment factor can be added to the denominator to prevent the denominator from being 0. This parameter adjustment factor is a very small positive number. For example, the value of this parameter adjustment factor can be 0.01. Its specific value can be set by the implementer according to the actual situation, and the embodiments of this application do not impose specific limitations.

[0021] Please refer to Figure 1, which shows a flowchart of a method for the resource utilization of anaerobic digester residue from kitchen waste according to an embodiment of the present invention. The method includes the following steps: Step S100, obtaining the blower speed and pipeline static pressure at the same moment when the blower is in the speed-up stage, constant speed stage and speed-down stage.

[0022] The main purpose of this step is to force the stack to exhibit rheological behaviors such as compression, creep, and rebound by controlling the blower to perform standardized aerodynamic actions of speed increase, constant speed, and speed decrease (actively applying stress), and then simultaneously collecting dynamic response data of speed and pressure, and finally extracting physical signals that can characterize compaction, blockage, and normal state.

[0023] First, considering that the initial fluid resistance baseline of the biogas residue pile to be dried varies significantly under different working conditions such as cold start, low load heat preservation, and full load fermentation, it is necessary to dynamically adapt the parameters to ensure that the detection action is sufficient to stimulate the mechanical response of the pile while avoiding the disruption of the current thermodynamic balance due to sudden changes in air volume.

[0024] Specifically, obtain the real-time operating speed of the blower at the current moment. Considering that in extreme scenarios such as system cold start and fault shutdown, the wind turbine may be stationary or at extremely low speeds, directly activating the detector in these conditions could result in airflow failing to penetrate the reactor core or excessively low signal-to-noise ratio in the collected data. Therefore, the system has a preset minimum speed limit. (For example, the fan speed corresponding to the inverter dead zone frequency) By comparing the real-time operating speed with the minimum speed limit, the larger of the two values ​​is taken as the preset reference speed of the blower under this active detection operation, that is, the reference speed. It can be represented as , max represents the maximum value function, which ensures that the detection action is always based on effective airflow.

[0025] Among them, active detection operation refers to actively applying controllable stimuli to the biogas residue pile, such as different rotation speeds and static pressures, to create stress change scenarios and fully expose the viscoelastic characteristics of the pile.

[0026] After determining the starting point of the blower speed, to induce nonlinear deformation of the material skeleton, a significantly higher aerodynamic stress than the current operating state needs to be applied. The target speed is typically set as the reference speed. The target speed should be 1.2 to 1.3 times the rated speed of the blower to create a sufficient stress gradient. Meanwhile, to avoid hardware overload, if the target speed exceeds the blower's rated speed, the blower's rated speed should be used as the target speed to ensure safe equipment operation.

[0027] It should be noted that when the reference speed When the target speed is close to the rated speed, setting the target speed by multiplying the speed may result in the blower's rated speed cutting off the speed and failing to form an effective acceleration range. This could lead to the inability to extract effective features during the active detection phase. In this case, a speed safety margin of 5Hz can be set. At that time, among them The reference speed is set according to the above strategy. This refers to the rated speed of the blower. To allow for a safety margin in rotational speed, a forced adjustment to the reference speed is initiated at this point. The adjusted reference speed is: First, a deceleration transition is performed, followed by trapezoidal wave detection to ensure sufficient boost margin.

[0028] The target rotational speed refers to the peak aerodynamic stress set to stimulate the rheological properties of the reactor core. Essentially, it is the peak rotational speed the blower needs to reach during active detection. Its core function is to force the reactor core to expose its true physical properties through sufficiently strong aerodynamic stress. The rated rotational speed of the blower can be directly obtained from the blower's manufacturer data. The target rotational speed multiplier can be set by the implementer according to the specific implementation scenario. The value set in this embodiment is an empirical value based on a large amount of experimental data.

[0029] Furthermore, since the rheological behavior of the material in the pile includes three different characteristics: instantaneous elastic deformation, hysteretic viscous flow, and long-term structural creep, a single constant wind pressure cannot fully excite and present these characteristics. Therefore, by controlling the blower to perform standardized trapezoidal wave actions of uniform speed increase, constant speed maintenance, and uniform speed decrease, the complete mechanical response of the pile can be obtained in a segmented excitation and separate capture manner, and the multiple rheological characteristics of the pile can be accurately separated.

[0030] Specifically, during the acceleration phase, the blower speed is controlled to linearly and uniformly increase from the reference speed to the target speed within a preset speed change duration. This process rapidly increases aerodynamic stress, forcing the reactor core skeleton to undergo compressive deformation, focusing on stimulating and capturing its elastic deformation and compression hardening characteristics. The speed change duration can be 10 to 15 seconds, which can be set by the implementer according to the specific real-time scenario.

[0031] During the constant-speed phase, the blower speed is controlled to remain constant at the target speed for a duration that can be set to 60 seconds, depending on the specific real-time scenario. This process, conducted under constant high shear stress, focuses on observing the stability of the reactor's pore structure and capturing its long-term structural creep behavior.

[0032] During the deceleration phase, the blower speed is controlled to linearly and uniformly decrease from the target speed to the reference speed within a preset deceleration time. This process gradually releases aerodynamic stress, focusing on observing the rebound and recovery capability of the reactor skeleton and capturing the irreversible deformation characteristics caused by its viscous flow. The deceleration time can be 10 to 15 seconds, which can be set by the implementer according to the specific real-time scenario.

[0033] Finally, using a static pressure sensor installed on the main ventilation duct and the feedback interface of the frequency converter, time-series data for each stage are collected at a fixed sampling frequency, including the fan speed and duct static pressure at each moment during the acceleration, constant speed, and deceleration stages. To improve the accuracy of subsequent calculations, preprocessing can be used to eliminate transition noise caused by mechanical inertia, which will not be elaborated here. The sampling frequency can be 10Hz.

[0034] In some embodiments, in order to eliminate motor start-up oscillations at the beginning of the action and overshoot fluctuations at the end, the data of the first and last seconds within the time window corresponding to the acceleration phase can also be eliminated to obtain the fan speed and pipeline static pressure that monotonically increase in the time sequence, which can be used for subsequent extraction of compression hardening features.

[0035] In some embodiments, since the inverter experiences a stabilization period after reaching the target speed via PID regulation, the system discards the data from the first 5.0 seconds of the constant speed phase to obtain the steady-state response. In other embodiments, to eliminate the interference of the randomness of the startup time on subsequent feature calculations, the time axis of the data in this phase can be reset. Specifically, the absolute time of the first sampling time point is set to... Then the timestamps of all data in the constant-rate phase will be mapped to relative time. ,in, This indicates the relative time of each data point during the constant-rate phase, corresponding to its timestamp. This represents the absolute time of the timestamp corresponding to each data point during the constant-rate phase (i.e., the timestamp recorded in real time).

[0036] In some embodiments, analogous to the operation during the acceleration phase, transitional data in the first and last seconds of the corresponding time window during the deceleration phase can be removed to obtain the monotonically decreasing turbine speed and pipeline static pressure in chronological order, providing a data foundation for subsequent feature extraction operations. This data preprocessing method is a well-known technology, and implementers can choose an appropriate method for processing according to the specific implementation scenario. It can effectively eliminate interference factors such as mechanical inertia and equipment stabilization periods, ensuring that the dataset can truly reflect the rheological response of the reactor itself, rather than equipment or operational noise.

[0037] It should be noted that, due to the mechanical response delay of large blowers, before performing subsequent feature analysis, the collected blower speed and pipeline static pressure data can be time-aligned by shifting the time axis of the speed data backward by a preset system response time (e.g., 0.5-2 seconds) to eliminate the false hysteresis loop caused by pure mechanical inertia.

[0038] Thus, this embodiment embeds an active detection period into the normal operating cycle, utilizing the blower to perform a standardized trapezoidal wave action comprising three stages: uniform acceleration, constant speed maintenance, and uniform deceleration. Simultaneously, time-series data of the blower's speed and static pressure are collected, providing a data foundation for subsequent analysis of characteristic performance under different conditions.

[0039] Step S200: Based on the rate of change of pipeline static pressure with fan speed during the acceleration phase, and considering the differences in the corresponding rates of change under different fan speed conditions, the compression hardening factor is obtained. Based on the difference in the average rate of change of pipeline static pressure with fan speed during the acceleration and deceleration phases, the degree of viscoelastic hysteresis damage is obtained; based on the rate of change of pipeline static pressure with time during the constant speed phase, the pore structure characteristic value is determined.

[0040] The main purpose of this step is to decouple the physical causes of ventilation resistance based on the differences in the mechanical response of the stack under different aerodynamic load stages, and to provide a scientific basis for subsequent rheological state determination by extracting characteristic parameters in three dimensions. This is closely related to the viscoelastic rheological properties of anaerobic digestate from food waste and the actual engineering requirements.

[0041] It should be noted that for the compacted state of materials, the main characteristics are that the viscoelastic properties lead to irreversible deformation (energy dissipation), the material becomes harder with each blow, and it cannot fully rebound after depressurization. For the blocked state of pipelines, the main characteristics are that the rigid and elastic properties (water accumulation, screen blockage) lead to stable resistance, and the paths overlap after depressurization (no energy dissipation).

[0042] During the acceleration phase, stress is applied by gradually increasing the fan speed to induce compressive hardening characteristics in the stockpile material, corresponding to the nonlinear densification characteristics of compaction. During the constant-speed phase, high stress is maintained by keeping the fan speed constant to observe the pore creep characteristics (i.e., slow collapse) of the stockpile material, corresponding to the long-term instability characteristics of compaction. During the deceleration phase, stress is released by gradually decreasing the fan speed to observe the rebound hysteresis characteristics (i.e., non-overlapping paths) of the stockpile material, corresponding to the viscous energy dissipation characteristics of compaction.

[0043] Based on this, different rheological characteristics can be separated temporally by analyzing three different rotational speed stages. To this end, this step extracts features from three dimensions: instantaneous response, cyclic differences, and long-term stability, constructing an analysis system covering the entire lifecycle of the reactor's mechanical behavior. This system not only conforms to the elastic rheological physical laws of biogas sludge but also precisely addresses the problem of traditional control methods failing to distinguish the causes of high drag, providing solid theoretical support for the subsequent formulation of differentiated control strategies. The specific implementation process is as follows.

[0044] The first step is to perform characteristic analysis on the pipeline static pressure and fan speed during the acceleration phase to obtain the compression hardening factor.

[0045] It should be understood that the acceleration phase is a process in which aerodynamic stress is gradually applied to the reactor body, and the rate of change of the static pressure in the pipeline with the fan speed directly reflects the instantaneous resistance response of the reactor body. The difference in this rate of change at different speeds is essentially the difference in the mechanical behavior of the reactor body skeleton under different stress levels. As a viscoelastic material rich in extracellular polymers, biogas residue will exhibit a nonlinear increase in resistance with increasing speed if structural compaction occurs, that is, it "gets harder with more pressure," with the rate of change in the high-speed range being significantly greater than that in the low-speed range; while the resistance growth corresponding to rigid blockage is closer to a linear law. Therefore, by integrating the instantaneous rate of change and the rate difference between speeds to extract the compression hardening factor, it is possible to accurately detect whether there is a nonlinear compaction trend in the reactor body, providing a core mechanical basis for distinguishing between material compaction and physical blockage, and is a fundamental step in achieving decoupling of resistance causes.

[0046] The compression hardening factor is a characteristic parameter for judging whether there is a nonlinear densification trend in kitchen waste biogas residue. The specific method for obtaining it is shown in Figure 2, which is achieved by steps S201 to S203.

[0047] Step S201: Based on the changes in pipeline static pressure and fan speed within a preset local time window at each moment of the acceleration phase, obtain the stiffness coefficient at each moment of the acceleration phase.

[0048] The acceleration phase is a process in which aerodynamic stress increases rapidly, corresponding to the physical scenario of the stack skeleton being forcibly compressed. This phase is most likely to induce the nonlinear densification response of the material (i.e., the compaction characteristic of becoming harder as it is blown). The rotation speed increases at a constant rate (linear change), without any additional interference caused by rotation speed fluctuations, making it easier to focus on the change law of material resistance with increasing stress.

[0049] Specifically, for any given moment within the acceleration phase, a linear fit is performed using the fan speed at each moment within the local time window at that moment as the abscissa and the pipeline static pressure at the same moment as the ordinate. The slope of the fitted line is then used as the stiffness coefficient at that moment. The linear fit can be performed using univariate linear regression, a well-known technique that will not be elaborated upon here.

[0050] As a concrete example, each moment and a certain number of moments before it can be considered as a local time window for that moment. The number of moments within the local time window can be 10% of the total number of moments in the acceleration phase. Implementers can set this according to the specific implementation scenario. By using the sliding window regression method, local data smoothing can be achieved, which can effectively filter high-frequency noise and obtain a stable stiffness change pattern.

[0051] The slope represents the increase in static pressure corresponding to a unit increase in rotational speed within a local time window at a given moment. Its magnitude reflects the resistance sensitivity of the current acceleration phase. In other words, the larger the stiffness coefficient value at each moment during the acceleration phase, the more significant the increase in static pressure under the same rotational speed increment, and the greater the resistance of the material in the reactor body.

[0052] Step S202: The ratio of the stiffness coefficient to the fan speed at each moment during the acceleration phase is taken as the aerodynamic drag coefficient at each moment during the acceleration phase.

[0053] Considering the aerodynamic characteristics of blowers, the air pressure naturally increases with the square of the rotational speed. This inherent characteristic of the equipment means that even if the material is not compacted, the stiffness coefficient will naturally increase with higher blower speeds. Therefore, by calculating the ratio of the stiffness coefficient to the blower speed, the amplification effect of the speed amplitude is eliminated, ensuring that the aerodynamic drag coefficient only reflects the material's own drag coefficient per unit speed.

[0054] Step S203: Based on the ratio of the difference between the aerodynamic drag coefficient at the high fan speed and the aerodynamic drag coefficient at the low fan speed during the acceleration phase, the compression hardening factor is obtained.

[0055] Specifically, the average value of the aerodynamic drag coefficient at a preset number of moments is obtained as the low-pressure drag coefficient according to the time sequence of the acceleration phase; the average value of the aerodynamic drag coefficient at a preset number of moments is obtained as the high-pressure drag coefficient according to the time sequence of the acceleration phase; and the ratio of the difference between the high-pressure drag coefficient and the low-pressure drag coefficient to the low-pressure drag coefficient is used as the compression hardening factor.

[0056] It should be understood that during the acceleration phase, the fan speed and pipeline static pressure gradually increase at each moment in chronological order. Therefore, a preset number of moments are selected sequentially in chronological order, representing the low-pressure state of the material in the reactor core. For the same reason, a preset number of moments are selected sequentially in reverse chronological order, representing the high-pressure state of the material in the reactor core. Furthermore, the low-pressure drag coefficient characterizes the drag performance of the material in the low-pressure state, and the high-pressure drag coefficient characterizes the drag performance of the material in the high-pressure state. In this embodiment, the preset number can be 20% of the total number, meaning the calculation of the low-pressure drag coefficient corresponds to the first 20% of the acceleration phase, and the calculation of the high-pressure drag coefficient corresponds to the last 20% of the acceleration phase.

[0057] The final compression hardening factor characterizes the relative difference between high-pressure and low-pressure resistance during the pressurization stage. Its value directly reflects whether the material exhibits a nonlinear densification characteristic of becoming harder with increasing pressure. A larger value of the compression hardening factor indicates that the material resistance increases nonlinearly with increasing aerodynamic stress, i.e., it becomes harder with increasing pressure, which is consistent with the physical characteristics of viscoelastic material compaction. A value less than 0 and smaller indicates that the resistance shows a linear or decreasing trend with increasing rotational speed, with no compressibility phenomenon, which is consistent with the physical characteristics of normal ventilation or rigid blockage.

[0058] It should be noted that, to ensure the calculation results are meaningful, in this embodiment of the application, when performing fractional operations, if the denominator is 0, a parameter adjustment factor can be added to the denominator to prevent the denominator from being 0. This parameter adjustment factor is a very small positive number. For example, the value of this parameter adjustment factor can be 0.01. Its specific value can be set by the implementer according to the actual situation, and this embodiment of the application does not impose a specific limitation.

[0059] The second step is to compare and analyze the data characteristics of the acceleration and deceleration phases to obtain the degree of viscoelastic hysteresis damage.

[0060] It is understandable that the acceleration and deceleration phases constitute a complete aerodynamic loading and unloading cycle. The viscoelastic nature of biogas residue determines that it will dissipate energy in this cycle, exhibiting a hysteresis effect, meaning that the loading (acceleration) and unloading (deceleration) paths do not overlap, resulting in different data change trends between the acceleration and deceleration phases. In contrast, rigid resistance sources such as pipeline water accumulation and screen blockage do not exhibit energy dissipation characteristics, and their loading and unloading paths are essentially the same, meaning that the data change trends between the acceleration and deceleration phases tend to be consistent. The core difference between the two lies directly in the average rate of change of pipeline static pressure with fan speed. Viscoelastic compaction leads to a significantly higher average rate of change in the acceleration phase than in the deceleration phase, while the average rates of change in the two phases corresponding to rigid blockage tend to be consistent. Therefore, quantifying the difference in the average rates of change between the two phases to obtain the degree of viscoelastic hysteresis damage allows us to utilize the rheological properties of the material itself to achieve a fundamental distinction between viscous compaction and rigid blockage from the perspective of energy dissipation, which is a key step in decoupling the causes of resistance.

[0061] Specifically, the stiffness coefficient at each moment during the deceleration phase is obtained; the degree of viscoelastic hysteresis damage is determined based on the difference between the mean stiffness coefficient at all moments during the acceleration phase and the mean stiffness coefficient at all moments during the deceleration phase.

[0062] It should be noted that, following the method of ensuring the same stiffness coefficient at each moment during the acceleration phase, the stiffness coefficient at each moment during the deceleration phase is obtained. Specifically, for any moment during the deceleration phase, a linear fit is performed with the fan speed at each moment within the local time window of that moment as the x-axis and the pipeline static pressure at the same moment as the y-axis. The slope of the fitted line is taken as the stiffness coefficient at that moment. The linear fit can be performed using univariate linear regression, both of which are well-known techniques and will not be elaborated upon here.

[0063] As a concrete example, the difference between the mean stiffness coefficient at all times during the acceleration phase and the mean stiffness coefficient at all times during the deceleration phase is calculated, and the ratio of this difference to the mean stiffness coefficient at all times during the acceleration phase is used as the viscoelastic hysteresis damage coefficient.

[0064] It should be noted that, to ensure the calculation results are meaningful, in this embodiment of the application, when performing fractional operations, if the denominator is 0, a parameter adjustment factor can be added to the denominator to prevent the denominator from being 0. This parameter adjustment factor is a very small positive number. For example, the value of this parameter adjustment factor can be 0.01. Its specific value can be set by the implementer according to the actual situation, and this embodiment of the application does not impose a specific limitation.

[0065] The difference between the mean stiffness coefficient at all times during the acceleration phase and the mean stiffness coefficient at all times during the deceleration phase characterizes the drag difference between the acceleration and deceleration phases. A larger difference indicates a greater drag difference between the acceleration and deceleration phases. Therefore, using the average stiffness coefficient during the acceleration phase as a benchmark, the difference is normalized to a proportional value to avoid the invalidation of the criterion due to differences in absolute stiffness (for example, the absolute stiffness of the reactor body may differ under different operating conditions, but the hysteresis ratio can be compared laterally). It should be understood that the mean values ​​calculated in this embodiment are all arithmetic mean values.

[0066] The difference in stiffness coefficient between the acceleration and deceleration phases is essentially an irreversible change in the resistance characteristics during acceleration and deceleration. This change stems from the energy dissipation of viscoelastic materials, while rigid or elastic objects do not have this characteristic. Therefore, the difference in stiffness coefficient can accurately quantify the degree of energy dissipation.

[0067] The degree of viscoelastic hysteresis damage characterizes the proportion of irreversible aerodynamic energy loss during the acceleration-deceleration cycle, and its magnitude reflects the physical properties of the resistance source. A larger value for the degree of viscoelastic hysteresis damage indicates that the average stiffness coefficient during acceleration is greater than that during deceleration, signifying greater aerodynamic energy loss, a higher degree of conformity to viscoelastic physical characteristics, and a greater likelihood of a material compaction state. When the value is close to 0, it indicates that only elastic deformation occurs during acceleration with no energy dissipation, and elastic potential energy is released during deceleration. The resistance characteristics are close to no irreversible change, conforming to the physical characteristics of elastic or rigid deformation, and a greater likelihood of a pipeline blockage state.

[0068] The third step involves performing characteristic analysis on the static pressure of the pipeline and the speed of the fan during the constant speed phase to obtain the characteristic values ​​of the pore structure.

[0069] The core value of the constant-velocity phase lies in eliminating the interference of rotational speed changes and focusing on the long-term mechanical response of the reactor core under constant aerodynamic loads. The stability of the reactor core's pore structure directly determines ventilation efficiency. In a compacted material state, the compressed pores will slowly collapse due to creep, causing the static pressure required to maintain a constant airflow to change continuously over time. In a rigidly blocked state, the pore structure is relatively stable, and the static pressure will not show significant time-dimensional drift. Therefore, determining the pore structure characteristic values ​​based on the rate of change of pipeline static pressure over time in the constant-velocity phase can capture the dynamic evolution of the pore structure, supplement the missing information in the time dimension of the characteristic analysis results of the first two dimensions, further verify the authenticity of the resistance causes, and make subsequent state determinations more comprehensive and reliable.

[0070] Specifically, a linear fit is performed with each moment within the constant-rate phase as the abscissa and the static pressure of the pipeline at the same moment as the ordinate. The slope of the fitted line is used as the characteristic value of the pore structure. In this embodiment, the least squares method is used for linear fitting. The slope of the fitted line represents the natural growth rate of static pressure per unit time within the constant-rate phase. The greater the rate, the faster the pores close or collapse, and the worse the aerodynamic stability of the reactor body.

[0071] When the pore structure characteristic value is greater than 0, it indicates that the static pressure continuously increases over time during the constant-rate stage, suggesting that the pores in the reactor body undergo slow collapse or rearrangement under constant stress, exhibiting a creep densification trend, consistent with the long-term compaction characteristics of viscoelastic materials. When the pore structure characteristic value is close to 0, it indicates that the static pressure is basically stable over time, suggesting that the resistance source has no time-dependent deformation (such as rigid obstructions like water accumulation or screen blockage), and the reactor body has good aerodynamic stability. When the pore structure characteristic value is less than 0, this situation is less likely, possibly due to slight rebound of the reactor body or sensor noise. In engineering, this is usually judged in conjunction with other characteristics and is generally not considered a valid creep signal.

[0072] Step S300: Determine the rheological state of the kitchen waste biogas residue based on the compression hardening factor, viscoelastic hysteresis damage degree, and pore structure characteristic value; set a safety boundary for the blower speed based on the rheological state of the kitchen waste biogas residue.

[0073] The main purpose of this step is to transform the micro-rheological characteristics obtained from decoupling into macro-engineering control strategies. By accurately determining the rheological state of kitchen waste residue and matching an appropriate fan speed safety boundary, the problem of excessive material compaction or pipeline drainage failure caused by misjudgment of high resistance conditions in traditional control can be fundamentally solved.

[0074] Firstly, the compressibility hardening factor, viscoelastic hysteresis damage degree, and pore structure characteristic value correspond to three core rheological mechanisms: the nonlinear densification trend of the pile, energy dissipation characteristics, and pore dynamic stability, respectively. A single characteristic cannot fully characterize the essential differences in the causes of resistance. For example, an increase in the compressibility hardening factor could be due to either material compaction or pipeline blockage, making misjudgment easy if relying solely on this feature. The viscoelastic hysteresis damage degree is a key indicator distinguishing between viscous compaction and rigid blockage. The pore structure characteristic value supplements the stability information over time; under compaction, pores will creep and collapse, while under blockage, the pore structure remains stable. Therefore, by setting threshold conditions for multiple feature combinations for joint judgment, we can integrate rheological information from different dimensions, eliminate the risk of misjudgment based on a single feature, and ensure that the judgment results of the rheological state (compacted organic material state, blocked pipeline state, and normal aeration state) are consistent with the actual causes of resistance, providing a reliable basis for the formulation of subsequent control strategies. The specific judgment process for the rheological state of kitchen waste biogas residue is as follows.

[0075] The first step is to determine that the kitchen waste biogas residue is in a compacted organic material state when the compression hardening factor, viscoelastic hysteresis damage degree, and pore structure characteristic value meet the first threshold condition.

[0076] The first threshold condition is that the compression hardening factor is greater than the preset hardening threshold, and the viscoelastic hysteresis damage degree is greater than the preset loss threshold.

[0077] When the compressibility hardening factor is greater than the preset hardening threshold, it indicates that the material resistance increases non-linearly during the acceleration phase, consistent with the characteristic of becoming harder with increasing airflow, and showing a tendency towards densification. This is the strength characteristic of compaction; only when the material skeleton is compressed by the airflow will the resistance increase non-linearly. If the compressibility hardening factor is less than or equal to the preset hardening threshold, it indicates that the resistance growth is gradual, directly ruling out the possibility of compaction.

[0078] When the degree of viscoelastic hysteresis damage is greater than the preset loss threshold, it indicates that there is significant energy dissipation between the acceleration and deceleration stages. This is the core characteristic of viscoelastic materials. Because kitchen waste residue is rich in EPS, molecular chain slippage will occur during compaction and deformation, resulting in irreversible energy loss. Rigid blockages (accumulated water, screen blockage) do not have this dissipation, and the value of the degree of viscoelastic hysteresis damage is close to 0.

[0079] When both thresholds mentioned above are met simultaneously, specifically when the first threshold condition is met, the pile exhibits characteristics of becoming increasingly hard with each blow and failing to fully rebound after depressurization. This aligns with the irreversible deformation characteristics of viscoelastic material compaction. In this case, further pressurization would exacerbate pore closure, necessitating a deceleration relaxation strategy. Based on this, the compaction state of kitchen waste biogas residue indicates that resistance increases non-linearly with rotational speed and exhibits significant viscous energy dissipation, consistent with the physical characteristics of organic material compaction.

[0080] As a specific example, the hardening threshold can be 0.15 and the loss threshold can be 0.2. Implementers can set these values ​​according to the specific implementation scenario. The values ​​in this implementation are empirical values ​​obtained through a large number of experiments.

[0081] The second step is to determine that the kitchen waste biogas residue is in a blocked state in the pipeline when the compression hardening factor, viscoelastic hysteresis damage degree, and pore structure characteristic value meet the second threshold condition.

[0082] The second threshold condition is that the compression hardening factor is greater than the preset hardening threshold or the pore structure characteristic value is greater than the preset drift threshold, and the viscoelastic hysteresis damage degree is less than or equal to the preset loss threshold.

[0083] When the degree of viscoelastic hysteresis damage is less than or equal to the preset loss threshold, it means that the change paths of the acceleration and deceleration stages are basically the same, with no energy dissipation or minimal energy dissipation. The resistance source is an elastic or rigid object, such as water accumulation, solid blockage, etc. This threshold condition can be used to effectively distinguish it from compacted viscoelastic objects.

[0084] When the characteristic value of the pore structure is greater than the preset drift threshold, it indicates that the static pressure continues to rise over time in the constant rate stage, which means that the pores of the pile body undergo slow collapse or rearrangement under constant stress, which is consistent with the long-term characteristics of the compaction of viscoelastic materials.

[0085] The logic of OR plus AND fully covers two typical cases of blockage. The first possibility is high-resistance blockage, such as severe sieve pore blockage. This is characterized by a compression hardening factor greater than a preset hardening threshold, and viscoelastic hysteresis damage less than or equal to a preset loss threshold. In this case, the resistance increases non-linearly, but there is no energy dissipation or only minimal energy dissipation. The second possibility is unstable blockage, such as slow accumulation of water in a pipe network. This is characterized by a pore structure characteristic value greater than a preset drift threshold, and viscoelastic hysteresis damage less than or equal to a preset loss threshold. This indicates that the static pressure continues to drift and rise during the constant-rate phase, but the accumulated water acts as rigid resistance, with no viscoelastic energy dissipation.

[0086] In other words, the first possibility is rigid blockage, such as when the sieve holes are blocked by solid particles, characterized by high and stable resistance (small porosity characteristic value) and no energy dissipation during loading and unloading (small hysteresis); the second possibility is cumulative blockage, such as when condensate accumulates in the pipeline network, characterized by resistance that increases continuously over time (large porosity characteristic value, i.e., drift exists), and the physical hysteresis of the gas-liquid two-phase flow is significantly less than the viscoelastic hysteresis of the material (i.e., relatively small hysteresis).

[0087] As a specific example, the drift threshold can be 5.0 Pa / s. Implementers can set it according to the specific implementation scenario. This implementation uses an empirical value obtained through a large number of experiments.

[0088] Based on this, when the second threshold condition is met, the stack exhibits high resistance or unstable pressure, but the paths overlap after depressurization, which is consistent with the mechanical characteristics of rigid blockages. At this time, it is even more necessary to execute a high-speed pulse purging strategy to remove the blockages.

[0089] The third step is to determine that the kitchen waste biogas residue is in a normal aeration state when the compression hardening factor, viscoelastic hysteresis damage degree, and pore structure characteristic value meet the second threshold condition. The third threshold condition is that neither the first nor the second threshold condition is met. This means that the material caking state, that is, the organic material compaction state and the pipeline blockage state are not met. This indicates that there are no abnormalities in the characteristic analysis results of the three dimensions, or only a slight abnormality in the single characteristic analysis result. At this time, the pile resistance is stable and there is no significant compaction or blockage trend. The boundary can be appropriately relaxed to adapt to the temperature control requirements (oxygen supply and dehumidification) of fermentation.

[0090] Secondly, the fundamental differences in the rheological states of different materials dictate vastly different requirements for blower speed. Adopting a uniform speed control would exacerbate operational conflicts. For compacted organic materials, biogas residue, being a viscoelastic material, suffers from irreversible pore closure due to excessively high speeds. Stress relaxation principles must be utilized to reduce the speed, creating conditions for material skeleton rebound and pore reconstruction. For blocked pipelines, where the resistance source is rigid water accumulation or screen blockage, low speeds exacerbate water accumulation. High speeds are needed to flush out the blockages and clear the pipeline. For normally ventilated conditions, the pile has good permeability, requiring ensuring oxygen supply while avoiding excessive compaction. Therefore, a moderately relaxed speed limit is necessary. Based on the physical characteristics of different states, setting targeted speed safety boundaries allows the control strategy to directly map the inherent requirements of the resistance source, avoiding process failures caused by traditional "one-size-fits-all" control and ensuring stable system operation under unobstructed airflow conditions.

[0091] Specifically, the first step is to use the product of the reference rotational speed and the preset attenuation coefficient as the rotational speed safety boundary for the compacted organic material.

[0092] The compacted state of organic materials, also known as a slab-like state, indicates that the material skeleton is at a critical stress state and exhibits a significant viscous memory effect. Maintaining or increasing the current air pressure at this point will lead to further pore closure, making recovery difficult. Therefore, stress relaxation can be triggered by reducing stress (speed), allowing the molecular chains to slowly reset and the particle skeleton to spring back, reconstructing the pore channels. This operation forcibly reduces the fan speed, utilizing the material's stress relaxation characteristics to allow the compressed skeleton to gradually spring back under low stress, restoring porosity. Simultaneously, pulse purging is disabled, and a pulse flag is set. This avoids instantaneous pressure surges caused by pulses, which can exacerbate compaction.

[0093] As a specific example, the attenuation coefficient ranges from [0.85, 0.95]. In this embodiment, the preferred value of the attenuation coefficient is 0.9. Implementers can set it according to the specific implementation scenario. This implementation is based on empirical values ​​obtained through a large number of experiments.

[0094] The second step is to use the blower's rated speed as a safety boundary for the blocked pipeline. Simultaneously, a pulse purging action is set up during the blocked pipeline operation.

[0095] A blocked pipe network indicates that the resistance source is non-viscous water or rigid blockages. In this case, reducing the air pressure will not only fail to solve the problem but will also exacerbate the water accumulation due to the reduced flow velocity. Therefore, the shear force generated by a high-velocity airflow can be used to break through the water film and peel off the blockage particles, which means removing the speed limit, maximizing the airflow velocity, and providing sufficient shear force. The pulse mode enhances the unblocking effect through short-duration high-speed impacts, avoiding the energy waste caused by continuous high speeds.

[0096] Simultaneously, activate the pulse purging action and set the pulse flag. This strategy allows the system to utilize the fluid shear force generated by high flow rates to flush away accumulated water in the pipe network.

[0097] Third, for normal ventilation, the product of the reference speed and the preset gain coefficient is used as the speed safety boundary; the attenuation coefficient is less than the gain coefficient.

[0098] Under normal aeration conditions, the pile has good permeability with no risk of compaction or blockage. Therefore, strict speed limits are unnecessary, and the safety margin can be appropriately relaxed to match the heat requirements of fermentation (e.g., more oxygen is needed during fermentation heating). As a concrete example, the safe speed margin can be expressed by the formula:

[0099] in, This indicates the safe operating speed boundary under normal ventilation conditions. Indicates the reference speed. This represents the preset gain coefficient. The preset adjustment coefficient has a value range of 0.45 to 0.55. In this embodiment... The preferred value is 0.5. Implementers can set it according to the specific implementation scenario. This implementation is based on empirical values ​​obtained through a large number of experiments. This indicates the rated speed of the blower, meaning the blower speed must be within the blower's rated performance range.

[0100] Set pulse indicator under normal ventilation conditions No pulse purging is required, avoiding unnecessary energy consumption. Under these conditions, the upper limit can be moderately increased from the base speed, while not exceeding the rated speed, reserving operational space for increased oxygen supply during aerobic fermentation.

[0101] It should be understood that the speed safety boundary refers to the highest hard constraint value that the blower speed is allowed to reach under the corresponding physical conditions.

[0102] Furthermore, through feature analysis of the three dimensions of acceleration phase, constant speed phase, and deceleration phase, non-invasive active detection testing was achieved. Speed ​​safety boundaries were set for different states. After the detection phase, the system enters the normal operation cycle. Within the speed safety boundaries of the corresponding physical state, it needs to adapt to the thermodynamic requirements (oxygen supply and dehumidification) of aerobic fermentation and output the final executable speed command, thus achieving rheological safety priority and temperature control requirements adaptation.

[0103] It should be noted that a complete process in this embodiment includes a detection phase and a regular operation cycle. That is, the system first starts regular operation, inserts an active detection during regular operation (collecting data to determine the status), and continues to complete the remaining regular operation after the detection is completed until the cycle ends.

[0104] Specifically, during the regular operating cycle after the rotation speed safety boundary is set, the air volume is adjusted based on the pile temperature to ensure the stability of the fermentation process. That is, aerobic fermentation needs to maintain a specific temperature range, and the oxygen supply needs to be adjusted if the temperature is too high or too low.

[0105] First, the system uses a PID temperature control algorithm to calculate the required airflow speed command based on the deviation between the real-time temperature of the reactor core and the set target temperature. Essentially, it obtains the actual temperature of the reactor core at the moment the deceleration phase ends, uses the temperature difference between the actual temperature and the system's set target temperature as input to the PID control algorithm, and outputs a speed command to control the blower.

[0106] Furthermore, this embodiment implements hard constraint control logic, comparing the fan speed in the speed command with the speed safety boundary corresponding to the current physical state judgment result, and taking the smaller value of the two as the final execution command. This logic ensures that no matter how strong the thermodynamic demand, the fan speed will never exceed the rheological safety boundary.

[0107] At the same time, if there is a pulse action, that is, the pulse flag is The system will perform pulse purging actions over time during the operating cycle. Specifically, a pulse is executed at the beginning of the current cycle, and after the pulse ends, the speed safety boundary limit is restored.

[0108] Finally, at the end of the current routine operation, the system records the speed command at the final moment. To ensure the temporal continuity of the control process, this value is directly assigned to the reference speed of the next control cycle. Through this cross-cycle state transfer, each round of active detection is naturally connected to the end point of the previous round, forming a closed-loop iterative adaptive control process.

[0109] It should be noted that the reference speed for each complete control cycle is derived from the fan speed value corresponding to the final speed execution command at the end of the previous control cycle. If it is the first cycle, the preset value can be taken as the reference speed in step S100.

[0110] It should be understood that the above process can be interpreted as performing PID temperature control under the constraint of the speed safety boundary, while simultaneously applying pulse purging if the physical state indicates a pipe network blockage, until the preset duration of the normal operation phase ends. After the normal operation phase concludes, the system locks the current final speed. Set it as the reference speed for the next cycle. The current detection and normal operation cycle ends, and the next cycle starts immediately or at a preset interval.

[0111] This step is a crucial link connecting the decoupling of rheological characteristics with actual ventilation control. Its logical design achieves a seamless connection between microscopic mechanisms and macroscopic control. The rheological characteristics extracted in the previous steps can only reflect the microscopic state of the reactor body and cannot directly affect the engineering equipment. However, this step transforms the microscopic characteristics into clear control objectives through state determination, and then transforms the control objectives into executable equipment parameters through safety boundary settings, forming a complete control closed loop. This design ensures both the scientific nature of the control strategy (based on rheological physical mechanisms) and the feasibility of engineering implementation (transformed into specific rotational speed parameters), effectively solving the problem of "disconnect between control strategy and physical mechanism" in traditional control, and providing a key guarantee for the stable operation of the food waste biogas residue resource utilization process.

[0112] This invention also provides a system for the resource utilization of anaerobic digestate from food waste. This system is used to implement a method for the resource utilization of anaerobic digestate from food waste. The system includes: a data acquisition module for acquiring the blower speed and pipeline static pressure at the same moment during the blower's acceleration, constant speed, and deceleration phases; a detection and testing module for obtaining a compressibility hardening factor based on the rate of change of pipeline static pressure with blower speed during the acceleration phase, combined with the differences in the corresponding rates of change under different blower speed states; obtaining the degree of viscoelastic hysteresis damage based on the difference in the average rate of change of pipeline static pressure with blower speed during the acceleration and deceleration phases; determining pore structure characteristic values ​​based on the rate of change of pipeline static pressure with time during the constant speed phase; judging the rheological state of the food waste digestate based on the compressibility hardening factor, the degree of viscoelastic hysteresis damage, and the pore structure characteristic values; and a routine operation module for setting a safety boundary for the blower speed based on the rheological state of the food waste digestate.

[0113] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for the resource utilization of anaerobic digestate residue from kitchen waste, characterized in that, The method includes the following steps: acquiring the blower speed and pipeline static pressure at the same moment during the blower's acceleration, constant speed, and deceleration phases; obtaining the compressibility hardening factor based on the rate of change of pipeline static pressure with blower speed during the acceleration phase, combined with the differences in the corresponding rates of change under different blower speed states; obtaining the degree of viscoelastic hysteresis damage based on the differences in the average rate of change of pipeline static pressure with blower speed during the acceleration and deceleration phases; determining the pore structure characteristic value based on the rate of change of pipeline static pressure with time during the constant speed phase; judging the rheological state of the kitchen waste biogas residue based on the compressibility hardening factor, the degree of viscoelastic hysteresis damage, and the pore structure characteristic value; and setting a safety boundary for the blower speed based on the rheological state of the kitchen waste biogas residue.

2. The method for resource utilization of anaerobic digestate residue from kitchen waste according to claim 1, characterized in that, The compression hardening factor is obtained based on the rate of change of pipeline static pressure with fan speed during the acceleration phase, combined with the differences in the rate of change corresponding to different fan speed states. Specifically, this includes: obtaining the stiffness coefficient at each moment of the acceleration phase based on the changes in pipeline static pressure and fan speed within a preset local time window at each moment; using the ratio of the stiffness coefficient to the fan speed at each moment of the acceleration phase as the aerodynamic drag coefficient at each moment of the acceleration phase; and obtaining the compression hardening factor based on the proportion of the difference between the aerodynamic drag coefficient at high fan speed and the aerodynamic drag coefficient at low fan speed during the acceleration phase.

3. The method for resource utilization of anaerobic digestate residue from kitchen waste according to claim 2, characterized in that, The method of obtaining the stiffness coefficient at each moment of the acceleration phase based on the changes in pipeline static pressure and fan speed within a preset local time window at each moment of the acceleration phase specifically includes: for any moment in the acceleration phase, using the fan speed at each moment within the local time window at that moment as the abscissa and the pipeline static pressure at the same moment as the ordinate, performing linear fitting, and using the slope of the fitted line as the stiffness coefficient at that moment.

4. A method for the resource utilization of anaerobic digestate residue from kitchen waste according to claim 2, characterized in that, The method for obtaining the compression hardening factor based on the ratio of the difference between the aerodynamic drag coefficient at high fan speed and low fan speed during the acceleration phase specifically includes: obtaining the average value of the aerodynamic drag coefficient at a predetermined number of moments in the chronological order of the acceleration phase as the low-pressure drag coefficient; obtaining the average value of the aerodynamic drag coefficient at a predetermined number of moments in the reverse chronological order of the acceleration phase as the high-pressure drag coefficient; and using the ratio of the difference between the high-pressure drag coefficient and the low-pressure drag coefficient to the low-pressure drag coefficient as the compression hardening factor.

5. A method for the resource utilization of anaerobic digestate residue from kitchen waste according to claim 2, characterized in that, The method for determining the degree of viscoelastic hysteresis damage based on the difference in the average rate of change of the static pressure in the pipeline network with the fan speed during the acceleration and deceleration phases specifically includes: obtaining the stiffness coefficient at each moment during the deceleration phase; and determining the degree of viscoelastic hysteresis damage based on the difference between the mean stiffness coefficient at all moments during the acceleration phase and the mean stiffness coefficient at all moments during the deceleration phase.

6. A method for the resource utilization of anaerobic digestate residue from kitchen waste according to claim 1, characterized in that, The method of determining the pore structure characteristic value based on the rate of change of pipeline static pressure with time during the constant-speed stage specifically includes: performing linear fitting with each moment in the constant-speed stage as the abscissa and the pipeline static pressure at the same moment as the ordinate, and taking the slope of the fitted line as the pore structure characteristic value.

7. A method for the resource utilization of anaerobic digestate residue from kitchen waste according to claim 1, characterized in that, The determination of the rheological state of kitchen waste biogas residue based on the compression hardening factor, viscoelastic hysteresis damage degree, and pore structure characteristic value specifically includes: when the compression hardening factor, viscoelastic hysteresis damage degree, and pore structure characteristic value meet a first threshold condition, the kitchen waste biogas residue is determined to be in an organic material compaction state; when the compression hardening factor, viscoelastic hysteresis damage degree, and pore structure characteristic value meet a second threshold condition, the kitchen waste biogas residue is determined to be in a pipeline blockage state; when the compression hardening factor, viscoelastic hysteresis damage degree, and pore structure characteristic value meet a third threshold condition, the kitchen waste biogas residue is determined to be in a normal aeration state; the first threshold condition is that the compression hardening factor is greater than a preset hardening threshold, and the viscoelastic hysteresis damage degree is greater than a preset loss threshold; the second threshold condition is that the compression hardening factor is greater than a preset hardening threshold or the pore structure characteristic value is greater than a preset drift threshold, and the viscoelastic hysteresis damage degree is less than or equal to a preset loss threshold; the third threshold condition is that neither the first threshold condition nor the second threshold condition is met.

8. A method for the resource utilization of anaerobic digestate residue from kitchen waste according to claim 7, characterized in that, The step of setting a safe boundary for the blower speed based on the rheological state of the kitchen waste biogas residue specifically includes: obtaining a preset reference speed for the blower; for the compacted state of organic materials, using the product of the reference speed and a preset attenuation coefficient as the safe boundary for the speed; for the blocked state of the pipeline network, using the rated speed of the blower as the safe boundary for the speed; for the normal ventilation state, using the product of the reference speed and a preset gain coefficient as the safe boundary for the speed; wherein the attenuation coefficient is less than the gain coefficient.

9. A method for the resource utilization of anaerobic digestate residue from kitchen waste according to claim 8, characterized in that, Set the pulse purging action when the pipeline is blocked.

10. A system for the resource utilization of anaerobic digestate residue from kitchen waste, characterized in that, This system is used to implement the steps of a method for the resource utilization of anaerobic digester residue from kitchen waste as described in any one of claims 1-9. The system includes: a data acquisition module for acquiring the blower speed and network static pressure at the same moment during the blower's acceleration, constant speed, and deceleration phases; a detection and testing module for obtaining a compressibility hardening factor based on the rate of change of network static pressure with blower speed during the acceleration phase, combined with the differences in the corresponding rates of change under different blower speed states; obtaining the degree of viscoelastic hysteresis damage based on the differences in the average rate of change of network static pressure with blower speed during the acceleration and deceleration phases; determining pore structure characteristic values ​​based on the rate of change of network static pressure with time during the constant speed phase; and judging the rheological state of the kitchen waste digester residue based on the compressibility hardening factor, the degree of viscoelastic hysteresis damage, and the pore structure characteristic values; and a routine operation module for setting a safety boundary for the blower speed based on the rheological state of the kitchen waste digester residue.

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