A water-soluble fertilizer closed double-shaft paddle high-efficiency stirring and dispersion control method for soil improvement

Abstract

The application discloses a water-soluble fertilizer closed double-shaft paddle efficient stirring and dispersion control method for soil improvement, and belongs to the technical field of organic fertilizer manufacturing. The method relies on a full-closed stirring system, tracks the crushing process of solid-phase hard agglomerates based on acoustic emission spectrum characteristics, solves Kolmogorov microscale in real time by peeling off effective mechanical dissipation power, dynamically adjusts rotating speed and tank pressure, quantifies flow field periodic degradation by using a chaos degradation index, injects non-periodic pseudo-random pulses, compensates pressure fluctuation and latent heat temperature control based on Dalton partial pressure law, and finally determines the homogenization endpoint by multi-parameter fusion and intelligently discharges. The application solves the problems of difficult crushing of micro-agglomerates, closed pressure interference on dissolution balance and mixed dead angle formed by flow field periodic degradation.

Description

Technical Field

[0001] This invention belongs to the field of organic fertilizer manufacturing technology, specifically relating to a closed-loop dual-shaft paddle high-efficiency stirring and dispersion control method for water-soluble fertilizers aimed at soil improvement. Background Technology

[0002] With the increasing demands for farmland quality protection in modern agriculture, water-soluble fertilizers for soil improvement play an irreplaceable role in improving soil structure, increasing organic matter content, and providing precise nutrient supply. These water-soluble fertilizers are typically rich in humic acid, amino acids, alginic acid, and various micronutrient chelates, and their physicochemical properties are far more complex than those of traditional inorganic fertilizers. In actual production, soil-improving water-soluble fertilizers involve the deep integration of various highly hygroscopic, easily agglomerated, and highly corrosive solid raw materials with a liquid medium. To ensure the effective release and spatially uniform distribution of active ingredients in the fertilizer components, industrial production places extremely stringent requirements on the macroscopic mixing uniformity, microscopic shear dispersion capacity, airtight safety of the production process, and adaptive control capabilities for complex material rheological states.

[0003] Utility model patent document CN203955071U discloses a dual-shaft stirring structure. This structure utilizes a parallel active and driven stirring shaft within a cylinder, along with a propeller plate and support plate with through-holes to construct a basic mechanical mixing framework. This technical solution is effective in addressing the physical displacement and macroscopic mixing of conventional granular materials, enabling the axial circulation of large quantities of material in a relatively short time. However, this type of solution is essentially a "rigid" mechanical mixing mode. For colloidal organic matter or high-molecular-weight organic components commonly found in water-soluble fertilizers used for soil improvement, these components exhibit significant non-Newtonian fluid characteristics and high viscosity during dissolution. Traditional propeller-type blade structures struggle to generate sufficient shear stress at the microscale to overcome intermolecular forces and mechanical interlocking forces. When humic acid powder or amino acid powder enters the later stages of liquid-phase dissolution, the rapid increase in local concentration leads to a surge in the apparent viscosity of the system. If the mixing system lacks a dynamic sensing and response mechanism for the real-time rheological properties of the material, and relies solely on constant mechanical rotation speed for propulsion, it is highly susceptible to an "envelope effect" at the microscopic level. This means that the core undissolved particles are completely encapsulated by an external high-viscosity colloidal layer, forming stable agglomerates that are difficult to break up through macroscopic flow. The existence of such microscopic agglomerates greatly limits the final homogenization level of the fertilizer's active ingredients.

[0004] In the production of water-soluble fertilizers for soil improvement, the dissolution of some raw materials (such as strongly alkaline humates or specific chelates) is often accompanied by a significant exothermic effect or a weak acid-base neutralization reaction. Thermodynamic processes inevitably lead to dynamic fluctuations in the pressure of the gas phase space inside the sealed tank. While existing technologies achieve tank sealing through mechanical structures, they generally lack functional components for actively sensing and controlling the internal environmental pressure and phase equilibrium. The instability of internal pressure not only poses potential production safety risks, but more importantly, the blind fluctuations in pressure directly interfere with the dynamic equilibrium of the gas-liquid interface, altering the escape rate of volatile components in the liquid phase, and consequently affecting the dissolution kinetics of poorly soluble active components, resulting in uncontrollable deviations in product concentration and component ratios between batches.

[0005] The invention patent with publication number CN112999952A attempts to enhance the pre-dispersion effect by introducing a mechanical vibrating screen and a scraping structure. However, due to the strong hygroscopicity and metal surface adhesion of materials such as humic acid and amino acids, high-intensity mechanical vibration can actually accelerate the adhesion and bridging of fine particles at the screen apertures, causing frequent equipment blockages and downtime for cleaning. More critically, existing devices of this type often employ a single-shaft stirring combined with auxiliary feeding power configuration. This configuration exhibits significant asymmetry in the radial and axial spatial distribution of the shear force field, easily creating near-zero stirring dead zones in the corner areas at the bottom of the tank or in the weak dynamic coupling areas where the two axes intersect. For components containing large organic molecules, this uneven spatial distribution of energy directly leads to a misalignment in the distribution of active ingredients on a macroscopic scale, significantly reducing the soil improvement effect of the final fertilizer after application in the field.

[0006] Existing technologies generally suffer from the following shortcomings when processing special water-soluble fertilizers for soil improvement: In a confined environment, thermodynamic pressure fluctuations and stirring kinetic parameters are disconnected. Existing solutions lack a mechanism to integrate pressure regulation with rheological control, failing to utilize latent heat of vaporization to actively regulate material temperature and optimize shear conditions. During prolonged shearing, non-Newtonian fluids tend to form an adaptive steady-state laminar boundary layer outside the overlap region. Existing fixed mechanical phase differences or simple speed-changing strategies cannot fundamentally disrupt this periodic degradation of the flow field, leading to mixing dead zones at the tank's corners. Summary of the Invention

[0007] The purpose of this invention is to provide a closed-loop biaxial impeller method for efficient mixing and dispersion control of water-soluble fertilizers for soil improvement. This method solves the technical problems in existing water-soluble fertilizer mixing technologies, such as the lack of rheological state closed-loop feedback and energy decoupling mechanisms, which leads to difficulties in effectively breaking up micro-aggregates, the inability to distinguish between mechanical energy heat dissipation and shear work, pressure fluctuations in the closed environment interfering with the dissolution balance, and the periodic degradation of the laminar boundary layer in the flow field, resulting in mixing dead zones.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for efficient mixing and dispersion control of water-soluble fertilizer using a closed-loop biaxial impeller for soil improvement, the method comprising the following steps: Step 1: The initial physical parameters of the raw materials are synchronously collected through the sensor array. The central control unit estimates the wetting behavior parameters based on this and controls the closed and controlled feeding. Step 2: The central control unit drives the first and second stirring shafts to run at the initial speed through the first and second frequency converters to establish a macroscopic circulating flow field; Step 3: Perform tracking and determination of the micro-fracture process of solid hard agglomerates based on acoustic emission spectrum characteristics. When the brittle fracture clustering process of solid hard agglomerates is determined to be over, step 4 is automatically triggered. Step 4: Perform adaptive optimization of power dissipation and Kolmogorov microscale targeted control under strong thermo-rheological coupling. The Kolmogorov microscale is calculated in real time by stripping the effective mechanical dissipation power, and the rotation speed and tank pressure are dynamically adjusted according to the comparison results of the Kolmogorov microscale and the characteristic size of the target aggregate. Step 5: Simultaneously execute spatial chaotic mixing quantification and dual-axis transient phase perturbation control, use chaotic degradation index to quantify the degree of periodic degradation of the flow field in real time, and inject non-periodic pseudo-random pulses to disrupt the laminar boundary layer; Step 6: Implement active compensation for pressure fluctuations in the closed environment and coordinated control of latent heat of vaporization based on Dalton's law of partial pressures to decompose the total pressure inside the tank into water vapor partial pressure and non-condensable gas partial pressure. Cooling and pressure balance are achieved by adjusting the water vapor partial pressure. Step 7: Determine the dispersion endpoint based on the multi-parameter fusion homogenization judgment logic, and execute intelligent closed material discharge.

[0009] Furthermore, the microscopic fragmentation tracking logic based on acoustic emission spectrum characteristics in step 3 includes: the central control unit acquires the full-band acoustic emission signal in real time, extracts the characteristic high-frequency band signal from 100 kHz to 500 kHz using wavelet packet transform for reconstruction, and obtains the high-frequency acoustic emission reconstructed signal; calculates the instantaneous energy release integral within the characteristic high-frequency band, wherein the instantaneous energy release integral is equal to the definite integral of the square of the modulus of the short-time Fourier transform spectrum of the high-frequency acoustic emission reconstructed signal between the lower limit frequency and the upper limit frequency of the characteristic high-frequency band.

[0010] Furthermore, the criterion for determining the end of solid-phase hard agglomerate fragmentation in step 3 is as follows: the central control unit defines the time derivative of the instantaneous energy release integral as the acoustic emission event occurrence rate index, and after the instantaneous energy release integral enters the exponential decay period, the decay time constant is extracted by fitting an exponential decay model. The exponential decay model is the instantaneous energy release integral equal to the initial decay amplitude multiplied by an exponential function of the ratio of negative time to decay time constant with the natural constant e as the base, plus the background noise baseline value; when the instantaneous energy release integral drops to within 1.2 times the preset background baseline value and lasts for more than three times the decay time constant, the physical fragmentation of the hard agglomerate is determined to be over.

[0011] Furthermore, the effective mechanical dissipation power stripping method in step 4 is as follows: the effective mechanical dissipation power is equal to the total input electrical power minus the product of the material's equivalent specific heat capacity, the material's cumulative total mass, and the material's temperature's first-order time derivative, and then minus the equipment's fixed loss power.

[0012] Furthermore, the calculation logic for the Kolmogorov microscale in step 4 is as follows: The turbulent energy dissipation rate is calculated based on the effective mechanical dissipation power. The turbulent energy dissipation rate is equal to the effective mechanical dissipation power divided by the product of the current material density and the effective mixing volume. The effective mixing volume is equal to the cumulative total mass of the material divided by the current material density. The apparent viscosity of the material is estimated in real time by combining the resistance torque feedback values ​​of the first and second stirring shafts, and the kinematic viscosity is calculated. The kinematic viscosity is equal to the apparent viscosity of the material divided by the current material density. The Kolmogorov microscale is calculated to be equal to the cube of the kinematic viscosity and the quarter power of the ratio of the turbulent energy dissipation rate.

[0013] Furthermore, the estimation of apparent viscosity in step 4 involves determining the average shear rate of the overlapping region: When the first and second stirring shafts rotate in the same direction, the average shear rate in the overlapping area is equal to the blade geometry minus the shear coefficient in the overlapping area multiplied by the absolute value of the difference between the rotational speeds of the first and second stirring shafts. When the first stirring shaft and the second stirring shaft rotate in opposite directions, the average shear rate of the overlapping area is equal to the blade geometry - the shear coefficient of the overlapping area multiplied by the sum of the rotational speed of the first stirring shaft and the rotational speed of the second stirring shaft; The apparent viscosity of the material is equal to the sum of the resistance torque feedback values ​​of the first and second stirring shafts, divided by the product of the resistance torque-stress conversion coefficient and the average shear rate of the overlapping region.

[0014] Furthermore, the targeted closed-loop control strategy in step 4 includes: the central control unit presets the target agglomerate characteristic size; when the Kolmogorov microscale is greater than or equal to the target agglomerate characteristic size, the thermo-rheological decoupling control subroutine is triggered, reducing the absolute rotational speed of the first and second stirring shafts to 60% to 80% of the set value, and simultaneously increasing the opening of the micro-pressure regulating valve, using the pressure reduction in the sealed tank to promote the absorption of latent heat of water evaporation, until the Kolmogorov microscale is smaller than the target agglomerate characteristic size.

[0015] Furthermore, the quantification method for the chaotic degradation index in step 5 is as follows: extract the power spectral density of the cross-correlation function between the drag torque feedback values ​​of the first and second stirring shafts; calculate based on the rotation frequencies of the first and second stirring shafts and their respective first N harmonic amplitudes, the chaotic degradation index is equal to the sum of the power spectral density amplitudes corresponding to the first N harmonics of the first stirring shaft rotation frequency and the sum of the power spectral density amplitudes corresponding to the first N harmonics of the second stirring shaft rotation frequency divided by the integral of the power spectral density in the range from zero to the Nyquist frequency; when the chaotic degradation index is greater than or equal to a preset chaotic degradation threshold, it is determined that the flow field has periodic degradation, where N is a preset harmonic number and takes a positive integer value.

[0016] Furthermore, the phase disturbance in step 5 is achieved by generating a pseudo-random binary sequence to control the second frequency converter, injecting a duration... for to Amplitude For the current frequency to The random frequency pulse correction amount.

[0017] Furthermore, the partial pressure of water vapor in step 6 The stripping logic is as follows: The central control unit calibrates the partial pressure of non-condensable gases based on initial static conditions. The current water vapor partial pressure is calculated in real time during the stirring process. ;in, This represents the total pressure inside the tank in the initial state; This represents the partial pressure of water vapor in the initial state; This indicates the current absolute temperature of the gas phase; This represents the absolute temperature of the gas phase in its initial state.

[0018] Furthermore, the cooling-coordinated control in step 6 involves the change in the mass of water evaporation. Calculation: in, This represents the additional mass of water vapor that the gas phase space can accommodate under the current non-equilibrium state compared to the saturated state; Indicates the current partial pressure of water vapor; Indicates real-time liquid phase temperature The corresponding saturated vapor pressure; Indicates the volume of the gas phase space; This represents the gas constant for water vapor, with a value of [value missing]. ; This indicates the absolute temperature of the liquid phase; the central control unit lowers the upper limit of the pressure control range. To increase Utilizing evaporation to absorb heat To achieve active temperature control, among which It is the latent heat of vaporization of water.

[0019] Furthermore, step 6 also includes pressure change rate feedforward prediction compensation logic: the central control unit uses second-order Taylor expansion to predict the pressure estimate. : like If so, the pre-opening command of the micro-pressure regulating valve will be output in advance; among which, This represents the current pressure inside the tank. This is the first derivative of the pressure. This is the second derivative of the pressure. To predict the time step; This represents the upper limit of the pressure control range.

[0020] Furthermore, in step 7, the homogenization determination feature vector is composed of conductivity, transmittance feature values ​​and a weighted average of drag torque. The determination criteria include: within N consecutive sampling periods, the relative rate of change of conductivity is always lower than the second preset conductivity rate of change threshold, the relative rate of change of transmittance feature values ​​is always lower than the second preset transmittance rate of change threshold, the relative fluctuation amplitude of the weighted average of drag torque is always lower than the third preset drag torque fluctuation threshold, and the instantaneous energy release integral in step 3 returns to the preset background baseline value, and the chaos degradation index in step 5 stabilizes below the preset chaos degradation threshold.

[0021] On the other hand, the present invention also discloses a fully enclosed stirring system for implementing the method described above, comprising: The mixing tank is equipped with an acoustic emission sensor on its outer wall and a dual-redundant first pressure sensor and second pressure sensor on its top. The number and spacing of the blades installed axially on the first and second stirring shafts are arranged asymmetrically to form a spatial chaos enhancement mechanism. The first drive motor and the second drive motor are driven by the first frequency converter and the second frequency converter respectively, which have energy feedback function; The pressure balancing assembly includes a micro-pressure regulating valve, a condensate recovery unit, and a gas supply valve; The central control unit has a pre-installed database of material moisture absorption characteristics, an Antoine equation parameter library, calibrated blade geometry-overlapping zone shear coefficient, and calibrated drag torque-stress conversion coefficient in its internal storage unit, and is equipped with a real-time operating system for executing the method.

[0022] In addition, the present invention also discloses a water-soluble fertilizer for soil improvement, which is prepared using the above-described system.

[0023] Compared with the prior art, the present invention has the following beneficial effects: This invention introduces a fracture cluster evolution tracking method based on acoustic emission spectrum characteristics. It directly captures the elastic stress waves released by the brittle cleavage of solid-phase hard agglomerates from the perspective of fracture mechanics. By extracting the decay time constant of the instantaneous energy release integral in the characteristic high-frequency band, the physical fragmentation endpoint of the hard agglomerates is accurately determined. This method effectively avoids the interference of temperature rise and viscosity decrease on the criteria in traditional resistance torque monitoring, providing an accurate basis for control switching in the subsequent high-viscosity dispersion stage. Simultaneously, this invention constructs an adaptive optimization method for power dissipation under strong thermo-rheological coupling and a Kolmogorov microscale targeted control method. By stripping away the effective mechanical dissipation power, it calculates the turbulent energy dissipation rate and Kolmogorov microscale in real time, and directly compares the Kolmogorov microscale with the target agglomerate characteristic size as the basis for closed-loop control. When it detects that the material viscosity decreases due to temperature rise, causing the Kolmogorov microscale to exceed the target agglomerate characteristic size, the central control unit actively reduces the stirring shaft speed and uses pressure regulation to promote evaporative cooling, prioritizing mechanical energy towards effective shear work, thus resolving the technical contradiction between high speed and high heat generation coupling in traditional stirring schemes.

[0024] This invention introduces a spatial chaotic mixing quantification and a biaxial transient phase perturbation control method. A chaotic degradation index is constructed by calculating the concentration of fundamental and harmonic energy in the cross-power spectral density of the drag torques of the first and second stirring shafts, thus quantifying the degree of periodic degradation of the flow field in real time. When the chaotic degradation index exceeds a preset chaotic degradation threshold, the central control unit injects a non-periodic pseudo-random frequency pulse into the second frequency converter, forcibly disrupting the laminar boundary layer adaptively formed by the non-Newtonian fluid during long-term shearing. The active perturbation at the software algorithm level and the asymmetric arrangement of the first and second blades at the hardware level work together to form a dual spatial and temporal chaos enhancement mechanism, suppressing the formation of mixing dead zones.

[0025] This invention, based on Dalton's law of partial pressures, decomposes the total pressure inside the tank into the partial pressures of water vapor and non-condensable gases. During the execution of the thermo-rheological decoupling control subroutine, the change in water evaporation mass is calculated based on the degree to which the water vapor partial pressure deviates from the saturated vapor pressure. The upper limit of the pressure control range is actively lowered to increase the rate of latent heat absorption, achieving forced cooling. Simultaneously, the multi-stage heat exchange structure of the condensation recovery unit condenses and recirculates the evaporated components, maintaining a constant liquid-to-solid ratio within the stirred tank. This method establishes a linkage mechanism between pressure regulation and rheological control, solving the problem of the disconnect between thermodynamic pressure fluctuations and stirring kinetic parameters during closed-loop stirring. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a flowchart of the overall control method of the present invention.

[0028] Figure 2 This is a flowchart of the microscopic fragmentation tracking and determination process based on acoustic emission spectrum characteristics according to the present invention. Detailed Implementation

[0029] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the embodiments of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0030] The following is in conjunction with the appendix Figures 1-2 The embodiments of the present invention will be described in detail below.

[0031] A closed-loop biaxial impeller high-efficiency mixing and dispersion control method for water-soluble fertilizers for soil improvement is disclosed. The method relies on a fully enclosed mixing system, which includes a mixing tank, a first mixing shaft, a second mixing shaft, a first drive motor, a second drive motor, a first frequency converter, a second frequency converter, a sensor array, a pressure balancing component, an online monitoring unit, and a central control unit. The first and second mixing shafts are installed parallel to each other inside the mixing tank. The first drive motor is connected to the first mixing shaft via the first frequency converter, and the second drive motor is connected to the second mixing shaft via the second frequency converter. Multiple first impellers are fixedly mounted on the first mixing shaft, and multiple second impellers are fixedly mounted on the second mixing shaft. The rotational trajectories of the first and second impellers overlap in space.

[0032] The sensor array includes a moisture monitoring sensor, a particle size monitoring sensor, a weight monitoring sensor, an acoustic emission sensor, a first pressure sensor, a second pressure sensor, and a temperature sensor. The acoustic emission sensor is installed at a specific location on the outer wall of the mixing tank to collect elastic stress wave signals generated inside the material due to the breakage of agglomerates in real time. The first and second pressure sensors are installed in the gas phase region at the top of the mixing tank, forming a dual-redundant pressure measurement structure.

[0033] The pressure balancing assembly includes a micro-pressure regulating valve, a condensate recovery unit, a gas supply valve, and a backup pressure relief circuit. The condensate recovery unit adopts a multi-stage heat exchange structure, including a first-stage heat exchanger and a second-stage heat exchanger.

[0034] The method includes the following steps: Step 1: Multi-dimensional sensing of initial material state and controlled, closed-loop feeding; Before the material enters the mixing tank, the initial physical parameters of the soil improvement raw materials are synchronously collected by a sensor array located at the inlet of the closed conveying unit. The sensor array includes a moisture monitoring sensor, a particle size monitoring sensor, and a weight monitoring sensor. The moisture monitoring sensor is used to obtain the real-time moisture content (by mass percentage) of the raw materials. The particle size monitoring sensor uses a non-contact optical measurement principle to identify the average particle size of solid particles. The weight monitoring sensor is located at the bottom support point of the mixing tank and is used to measure the cumulative total mass of the material entering the mixing tank in real time.

[0035] The central control unit estimates the wetting behavior parameters of the material during the initial mixing stage based on the collected moisture content (mass percentage) and average particle size data, combined with a preset material hygroscopic characteristics database. Based on this, it dynamically adjusts the feeding rate of the closed conveying unit. The closed conveying unit includes a screw conveyor and a sealing valve assembly. The sealing valve assembly performs opening and closing switching actions at a first preset time interval to ensure that the gas phase pressure inside the mixing tank remains within a first preset pressure threshold range during the material's entry into the mixing tank. The first preset pressure threshold is set based on the intersection of the structural design pressure bearing limit of the mixing tank and the saturated vapor pressure curve of the volatile components in the material. This ensures that the mixing tank is always under a slightly positive pressure during the feeding stage to prevent external ambient air from carrying moisture into the tank and causing the material to pre-absorb moisture and clump.

[0036] Step 2: Dual-shaft frequency conversion coordinated start-up and active construction of macroscopic flow field; After initial feeding, the central control unit drives the first and second stirring shafts to start rotating. The axial distance between the first and second stirring shafts is less than the sum of the outer radii of the first and second blades, causing the motion trajectories of the first and second blades to form an overlapping area in the central region of the mixing tank. The installation angles of the multiple first blades on the first stirring shaft are spirally ascending along the axial direction, and the installation angles of the multiple second blades on the second stirring shaft are also spirally ascending along the axial direction. The axial distances between adjacent first blades and adjacent second blades satisfy the geometric conditions for the material to obtain displacement components in both the radial and axial directions simultaneously.

[0037] Based on the initial cumulative total mass and initial average particle size of the material obtained in step 1, the central control unit determines the initial rotational speeds of the first and second stirring shafts by querying a pre-stored rotational speed mapping table in the storage unit. This rotational speed mapping table is constructed using prior fluid dynamics simulation and experimental calibration data for different material formulations. Its input variables are the total mass and average particle size of the material, and its output variable is the minimum combination of rotational speeds required to establish a stable macroscopic circulating flow field. The central control unit adjusts the power supply frequencies of the first and second drive motors via the first and second frequency converters, respectively, to ensure that the first and second stirring shafts operate at their initial rotational speeds. During this stage, the first and second stirring shafts rotate in the same direction to rapidly establish a large-scale circulating macroscopic flow field covering the entire tank inside the mixing vessel, achieving rapid wetting and initial macroscopic mixing of the solid particles.

[0038] During the execution of step 2, the central control unit also executes phase angle dynamic collision prevention control logic. A first phase encoder is configured at the drive end of the first stirring shaft, and a second phase encoder is configured at the drive end of the second stirring shaft. The first and second phase encoders respectively feed back the instantaneous first phase angle of the first stirring shaft and the instantaneous second phase angle of the second stirring shaft to the central control unit in real time. The central control unit calculates the real-time minimum distance between the tips of the first and second blades within the overlap area using a preset spatial position function. The spatial position function uses the first phase angle, the second phase angle, the geometric installation parameters of the first blade, and the geometric installation parameters of the second blade as independent variables, and outputs a predicted minimum gap value between the two blades. When the predicted minimum gap value is less than a preset safe phase difference threshold, the central control unit fine-tunes the pulse width modulation output frequency of the second frequency converter, causing the second stirring shaft to accelerate and decelerate instantaneously, thereby dynamically correcting the second phase angle to ensure that the first and second blades maintain a safe phase difference within the overlap area to prevent mechanical collision.

[0039] Step 3: Tracking and determining the microscopic fragmentation process of solid-phase hard agglomerates based on acoustic emission spectrum characteristics; After the macroscopic flow field is established, with the liquid phase wetting effect, solid-phase hard agglomerates (such as mineral-derived potassium humate powder particles, potassium dihydrogen phosphate crystals, etc.) begin to undergo brittle fracture and dissociation. In order to accurately identify the physical process of agglomerates from initial fragmentation to complete dissociation, and to solve the technical problem that traditional drag torque monitoring cannot distinguish between "temperature rise and viscosity drop" and "actual fragmentation", Step 3 executes the microscopic fragmentation cluster evolution tracking logic based on acoustic emission spectrum characteristics.

[0040] The acoustic emission sensor is installed at a specific location on the outer wall of the mixing tank, preferably in the area where the effective material circulation path meets the tank wall. The central control unit uses a high-frequency sampling method (sampling rate not lower than...). Real-time acquisition of full-band acoustic emission signals output by acoustic emission sensors .

[0041] Central control unit for acoustic emission signals Perform wavelet packet transform multi-scale decomposition. The wavelet packet transform uses Daubechies-10 wavelet basis functions, and the decomposition level is [number missing]. Layers are created to obtain sub-band signal components covering different frequency bands. The central control unit identifies and extracts characteristic high-frequency band signal components characterizing the brittle fracture of hard crystals. These characteristic high-frequency bands are defined as... to This frequency band encompasses the dominant frequency range of elastic stress waves released by typical fertilizer raw materials such as humic acid mineral particles and phosphate crystals during brittle cleavage under shear stress. The central control unit reconstructs the signal components of each sub-band within the characteristic high-frequency band to obtain the high-frequency acoustic emission reconstruction signal. This effectively filters out motor operating vibrations (usually less than 1000 m / s). ), fluid turbulence friction noise (typically distributed in to Low-frequency background interference, such as , etc.

[0042] The central control unit calculates the high-frequency acoustic emission reconstruction signal based on short-time Fourier transform. time spectrum Set the time window length to The overlap rate is The frequency resolution is The central control unit calculates the integral of instantaneous energy release within the characteristic high-frequency band. Its mathematical expression is: in, Indicates time Integral of instantaneous energy release at that time; This represents the lower limit frequency of the characteristic high-frequency band, and its value is... ; This represents the upper limit frequency of the characteristic high-frequency band, and its value is... ; This indicates that the high-frequency acoustic emission reconstruction signal is at a frequency of ,time The short-time Fourier transform spectrum at the location; This represents the corresponding power spectral density.

[0043] Central control unit integrates instantaneous energy release Perform fracture cluster dynamics analysis. Define the time derivative of the energy release integral. This is an indicator of the acoustic emission event rate. In the initial fragmentation stage, a large number of hard aggregates fracture simultaneously under high shear in the overlapping region. It experiences a rapid increase and reaches a positive peak; as fragile aggregates are consumed, the rate of new fracture events begins to decline. From positive to negative; after most of the aggregates have been broken down. Entering the exponential decay period. The central control unit performs real-time fitting. The decay curve is fitted using the following exponential decay model with nonlinear least squares: in, Represents the integral of instantaneous energy release; Indicates the initial amplitude of decay; Represented by natural constant An exponential function with base 0; Indicates time; Indicates the decay time constant; This represents the baseline value of the background noise.

[0044] Central control unit continuously monitors The decay process. When Drop to the preset background baseline value of Within two times, and the duration exceeds At this point, the central control unit determines that the brittle fracture and aggregation process of the solid hard agglomerates has essentially ended. At this time, the hard agglomerates in the material system have been completely physically pulverized, and the material enters a high-viscosity dispersion stage dominated by the colloidal envelope effect. Based on this, the central control unit issues a first-stage completion signal, automatically triggering the switch to step 4.

[0045] Step 4: Adaptive optimization of power dissipation and Kolmogorov microscale targeted control under strong thermo-rheological coupling; As solid particles are pulverized and dissolved into the liquid phase, the apparent viscosity of the system increases sharply due to the dissolution of organic macromolecules such as humic acid and amino acids, and the material exhibits typical shear-thinning non-Newtonian fluid characteristics. At this stage, it is crucial to ensure that the input mechanical energy is effectively converted into shear work to overcome viscous resistance, rather than into internal fluid energy leading to an unnecessary temperature increase, thus breaking the technical deadlock of "high speed - high heat generation - low shear." Step 4 executes adaptive optimization for power dissipation under strong thermo-rheological coupling and Kolmogorov microscale targeted control logic.

[0046] The central control unit collects the total input power of the first and second frequency converters in real time. Simultaneously, the absolute temperature of the material is obtained through a temperature sensor. (unit The total cumulative mass of materials obtained through step 1) And the material equivalent specific heat capacity pre-stored in the material parameter database. Equivalent specific heat capacity The value is calculated using a weighted average based on the proportions of the formulation components. The central control unit calculates the rate of increase in the internal energy of the material system per unit time. in, Indicates the rate of increase in internal energy of the material system; Indicates the equivalent specific heat capacity of the material; Indicates the total cumulative mass of materials; The first time derivative of the material temperature.

[0047] The central control unit further incorporates fixed power losses from the equipment. This includes iron losses, copper losses, and bearing friction losses in the first and second drive motors. The power obtained through preliminary no-load calibration experiments is stored in the storage unit. Based on the principle of energy conservation, the central control unit extracts the effective mechanical dissipation power. : in, Indicates effective mechanical power dissipation; Indicates the total input electrical power; This indicates the fixed power loss of the equipment.

[0048] The central control unit calculates the turbulent energy dissipation rate. According to the turbulence theory in a stirred tank, the average energy dissipation rate per unit mass of fluid is... Calculated by the following formula: in, Indicates the turbulent energy dissipation rate; Indicates effective mechanical power dissipation; This indicates the current material density, which is estimated in real time by the central control unit based on the formula data and temperature compensation coefficient. The effective mixing volume is represented by the total cumulative mass of the material measured by the weight monitoring sensor. Divide by the current material density The actual volume occupied by the obtained material is, i.e. .

[0049] The central control unit is based on the resistance torque feedback values ​​of the first and second stirring shafts. and Combined with the current speed and Real-time estimation of the apparent viscosity of materials Average shear rate in the overlapping region Precisely determined by biaxial kinematic relationships: When the first stirring shaft and the second stirring shaft rotate in the same direction, the average shear rate ; When the first stirring shaft rotates in opposite directions to the second stirring shaft, the average shear rate ; in, The shear coefficient of the blade geometry-overlapping zone is determined by the geometric dimensions, installation angle, and overlap width of the first and second blades. It is determined by a combination of computational fluid dynamics simulation of this stirring system and calibration experiments using standard viscosity fluid, and is pre-stored in the storage unit.

[0050] Apparent viscosity Calculated using the following formula: in, Indicates the apparent viscosity of the material; This represents the feedback value of the resistance torque of the first stirring shaft; This indicates the resistance torque feedback value of the second stirring shaft; The drag torque-stress conversion coefficient, which represents the geometry of the stirring system, is determined by a combination of computational fluid dynamics simulation of the stirring system and calibration experiments using a standard viscosity fluid, and is pre-stored in the storage unit. This represents the average shear rate within the overlapping region.

[0051] The central control unit calculates the kinematic viscosity of the material. .

[0052] Furthermore, the central control unit calculates the real-time microscale length based on Kolmogorov's turbulent microscale theory. : in, Represents the Kolmogorov microscale; Indicates the kinematic viscosity of the material; This represents the turbulent energy dissipation rate.

[0053] Kolmogorov microscale It characterizes the feature size of the minimum vortex in the turbulent energy cascade process. Only when Smaller than the characteristic size of the target aggregate Only when the turbulent vortex penetrates deep into the viscous subsurface of the aggregate can it effectively peel off the colloidal layer surrounding the particles, thereby achieving dispersion at the microscale.

[0054] The central control unit presets the target aggregate characteristic size. For water-soluble fertilizers used for soil improvement, Typical setting value The central control unit continuously compares the results calculated in real time. and Based on the comparison results, the following targeted closed-loop control strategy will be implemented: (1) When This indicates that the current turbulent microscale is sufficient to effectively break up the agglomerates. The central control unit maintains the current relative speed difference between the first and second stirring shafts. And absolute speed level, and continue to monitor. The changing trend.

[0055] (2) When the viscosity decreases due to the increase in material temperature ( reduce, (reduced), thus making When this occurs, it indicates that the fluid can no longer generate sufficiently fine shear vortices to peel off the colloidal layer. At this point, simply increasing the rotational speed will exacerbate heating, creating a vicious cycle. The central control unit immediately executes the thermo-rheological decoupling control subroutine: Reduce the absolute speed of the first and second stirring shafts to the current set value. to This is to reduce the heat dissipation component in the mechanical energy input.

[0056] Simultaneously increase the opening of the micro-pressure regulating valve, while reducing or cutting off the supply of heating medium to the insulation jacket. Utilize the reduction in pressure inside the sealed tank to promote the absorption of latent heat of vaporization of water in the liquid phase, thereby forcibly reducing the material temperature.

[0057] The central control unit continuously monitors the material temperature. and kinematic viscosity When the temperature drops to a level that causes the kinematic viscosity to decrease... Rebound, and regain satisfaction When the conditions are met, the central control unit restores the rotational speed of the first and second stirring shafts to the level required for target control, and restores the micro-pressure regulating valve to the normal pressure control mode.

[0058] Step 5: Spatial chaotic hybrid quantification and biaxial transient phase perturbation control; During prolonged microscopic shear dispersion, non-Newtonian fluids tend to adaptively form a steady-state laminar boundary layer. Even in the biaxial overlap region with high-intensity shear, the ends of the tank and the near-wall region may still form mixing dead zones with near-zero flow velocities due to the periodic enhancement of the flow field. Existing fixed mechanical phase difference or simple variable speed strategies cannot fundamentally eliminate this periodic degradation of the flow field. Step 5 executes spatial chaotic mixing quantification and biaxial transient phase perturbation control logic to maintain the chaotic mixing state throughout the entire tank.

[0059] The central control unit uses a sliding time window (Typical value set as) to Extract the resistance torque feedback value of the first stirring shaft. Feedback value of resistance torque with the second stirring shaft Time series. Perform cross-correlation function on two time series. Calculation: in, Represents the cross-correlation function; Indicates a sliding time window; This represents the feedback value of the resistance torque of the first stirring shaft; This indicates the feedback value of the resistance torque of the second stirring shaft over time. The value; This represents a variable with a time lag.

[0060] Central control unit for cross-correlation function Perform a fast Fourier transform to obtain the cross-power spectral density function. Considering that the first and second stirring shafts have independent and different rotational frequencies under differential speed operation, the central control unit extracts the rotational frequency of the first stirring shaft. and its integer multiples ( The cross-power spectrum amplitude at () and the rotation frequency of the second stirring shaft. and its integer multiples ( The cross-power spectral amplitude at () is defined. The chaotic degeneracy index is defined. for: in, Indicates a chaotic degradation index; This indicates the harmonic order being considered, and its value is... ; Indicates the cross power spectral density at The amplitude at the first stirring shaft rotation frequency; Indicates the cross power spectral density at The amplitude at twice the rotational frequency of the second stirring shaft; The Nyquist frequency is determined by the sampling frequency of the central control unit. This represents the cross-power spectral density function.

[0061] Chaos Degeneration Index This characterizes the concentration of flow field energy at the fundamental frequency and harmonics of the first and second stirring shafts, respectively. When the flow field is in a fully developed chaotic mixing state, the energy is uniformly distributed across a wide frequency band. The values ​​are relatively low; when the flow field degenerates into a highly periodic laminar island steady state, the energy is concentrated in the aforementioned discrete resonance peaks. The value increased significantly.

[0062] The central control unit presets a chaos degradation threshold. , Based on preliminary experimental calibration, the typical value is determined to be... to .when At that time, the central control unit determined that the flow field inside the mixing tank had shown significant periodic degradation and that there was a tendency to form a mixing dead zone.

[0063] After triggering the chaotic degradation determination, the central control unit executes the non-periodic pseudo-random pulse injection subroutine, the specific steps of which are as follows: The central control unit maintains the output frequency of the first frequency converter. Unchanged (i.e., the speed of the first stirring shaft remains unchanged) (Keep constant).

[0064] The central control unit generates a pseudo-random binary sequence. This sequence controls the transient correction of the output frequency of the second frequency converter. The pulse injection rules are as follows: every interval time( exist to (randomly varying within a range), a duration of [unclear] is superimposed on the output frequency of the second frequency converter. The pulse correction amount. Set as to Random values ​​between these ranges. Pulse amplitude. Determined by a pseudo-random number generator, the range is set to the current frequency. of to .

[0065] During the pulse, the angular velocity of the second stirring shaft generates a transient perturbation. This perturbation disrupts the established quasi-steady-state momentum coupling mode between the two axes, forcing the injection of non-periodic asymmetric momentum exchange into the flow field.

[0066] After each pulse injection, the central control unit re-acquires data. and Sequence, calculate the updated chaos degeneration index .like Falling back to The pulse injection will then be paused, and the normal control mode will be restored; if Still higher If so, continue with the next round of pulse injection.

[0067] Step 6: Active compensation for pressure fluctuations in a closed environment and coordinated control of latent heat of vaporization based on Dalton's law of partial pressures; During microscopic shear dispersion and chaotic mixing, the pressure in the gas phase space within the stirred tank continuously fluctuates due to the exothermic dissolution of materials, the conversion of mechanical shear work into heat energy, and the dynamic processes of water evaporation and condensation. Without proactive intervention to address these pressure fluctuations, the mass transfer balance at the gas-liquid interface will be affected, thereby interfering with the consistency between the dissolution rate and the final product concentration. Step 6 executes a closed-environment pressure fluctuation proactive compensation and latent heat of vaporization synergistic control logic based on Dalton's law of partial pressures.

[0068] The central control unit acquires the tank pressure in real time through a first pressure sensor and a second pressure sensor installed in the gas phase zone at the top of the mixing tank. And the gas phase temperature is obtained in real time through a temperature sensor. The first and second pressure sensors form a dual-redundant measurement structure. The central control unit performs an arithmetic average of the output values ​​from the two pressure sensors to obtain the result. It also compares the readings of the two pressure sensors in real time. When the reading deviation exceeds a preset deviation threshold, the central control unit triggers a fault warning signal and automatically switches to single-sensor operation mode.

[0069] The central control unit, based on Dalton's law of partial pressure, controls the total pressure inside the tank. Decomposed into water vapor partial pressure partial pressure of noncondensable gases : in, This indicates the measured total pressure inside the tank; Indicates the partial pressure of water vapor; This indicates the partial pressure of noncondensable gases. The initial value is calibrated in a static state after feeding is completed but before stirring begins: at this time, the liquid phase has not yet undergone significant exothermic or dissolution. If the value is the saturated vapor pressure at the current temperature, then... During subsequent stirring, if there is no leakage or replenishment of non-condensable gases, The ideal gas law applies as temperature changes, i.e. .

[0070] The central control unit based on real-time temperature Using the Antoine equation parameters for volatile components provided by the material composition database, calculate the saturated vapor pressure of the liquid phase components at the current temperature. The Antoine equation is in the form of: in These are characteristic constants related to the components. Temperature (unit) For water-soluble fertilizer systems, the main volatile component is water. , , For formulations containing low-molecular-weight organic acids, the central control unit calls the corresponding Antoine constants to perform partial pressure superposition calculations based on the component ratios.

[0071] The central control unit sets the target pressure range as follows: ,in and These are the lower and upper pressure limits, determined based on the structural strength and dissolution kinetics optimization requirements of the stirred tank.

[0072] When detected At this time, the central control unit outputs a control signal to the micro-pressure regulating valve, increasing the valve's opening proportionally to guide a portion of the gas in the gas phase space to the condensation recovery unit. The condensation recovery unit employs a multi-stage heat exchange structure: the first-stage heat exchanger uses ambient temperature circulating cooling water to pre-cool the incoming gas phase, causing pre-condensation of the higher-boiling-point vapor components; the second-stage heat exchanger uses a low-temperature refrigerant to deeply condense the pre-cooled gas phase, ensuring complete liquefaction of the low-boiling-point volatile components. The condensed liquid phase components flow back to the stirred tank via a return pipeline under gravity, thus maintaining a constant liquid-to-solid ratio within the stirred tank while depressurizing. If the pressure inside the tank continues to rise and approaches the safe release threshold after the micro-pressure regulating valve is fully open... The central control unit automatically activates the backup pressure relief circuit, and the gas phase is discharged in a controlled manner after being filtered by a multi-stage filtration device to remove entrained dust.

[0073] When detected At this time, the central control unit opens the gas replenishment valve to replenish the gas phase space of the mixing tank with dry inert gas (such as nitrogen), so that the pressure inside the tank rises back to the target range, while preventing the intrusion of external humid air.

[0074] Furthermore, step 6 also includes pressure change rate feedforward prediction and compensation logic. The central control unit continuously calculates the first derivative of the pressure. With the second derivative .when Exceeding the preset rate of change threshold and A positive value indicates that the pressure is in an accelerating upward phase. Based on the current pressure change trend, the central control unit uses a second-order Taylor expansion to predict the future... Estimated stress levels after time step: in, Indicates the estimated stress level; Indicates the current pressure inside the tank; This represents the first derivative of pressure; This represents the second derivative of pressure. Indicates the prediction time step, with values ​​ranging from 1 to 2. to .

[0075] like If the central control unit outputs a pre-opening command for the micro-pressure regulating valve in advance, it will counteract the pressure overshoot inertia and suppress the actual pressure peak within the target range.

[0076] Specifically, during the execution of the thermo-rheological decoupling control subroutine in step 4, the central control unit links the pressure control target with the cooling demand. When forced evaporative cooling is required, the amount of water evaporated... Precise calculation based on the deviation of water vapor partial pressure: in, This represents the additional mass of water vapor that the gas phase space can accommodate under the current non-equilibrium state compared to the saturated state; Indicates the current partial pressure of water vapor, by Calculated in real time; Indicates the current liquid phase temperature The corresponding saturated vapor pressure; This represents the volume of the gas phase space inside the mixing tank, and is calculated as the sum of the total volume of the mixing tank and the actual volume occupied by the material. difference; This represents the gas constant for water vapor, with a value of [value missing]. ; This indicates the absolute temperature of the liquid phase.

[0077] Heat absorbed by evaporation ,in The latent heat of vaporization of water (approximately at room temperature) The central control unit actively lowers the upper limit of the target pressure range based on the required cooling rate. By increasing Accelerate evaporation and cooling; once the temperature returns to the target range, restore the original pressure control range.

[0078] Step 7: Multi-parameter fusion homogenization judgment and intelligent closed material discharge; As the stirring and dispersion process proceeds, the material system gradually approaches a thermodynamically stable state. To accurately determine the dispersion endpoint and avoid energy waste and active ingredient degradation risks caused by over-stirring, step 7 executes a multi-parameter fusion homogenization determination logic.

[0079] The online monitoring unit is integrated into the sampling bypass on the side wall of the mixing tank or directly immersed in the effective mixing area inside the tank. The online monitoring unit includes an immersion conductivity probe and a near-infrared spectroscopy sensor. The conductivity probe outputs the conductivity value of the liquid phase of the material in real time. It is used to reflect the ionization equilibrium state of fertilizer salt ions in aqueous solution; the near-infrared spectroscopy sensor detects the transmittance or reflectance absorption intensity at a specific wavelength, and converts it into the concentration characteristic value of suspended particles in the solution through a multivariate calibration model. The multivariate calibration model is a partial least squares regression model for this material system, which was established and stored in the central control unit through previous experimental calibration.

[0080] The central control unit uses a fixed sampling period collection and The data, combined with the weighted average of the resistance torques of the first and second stirring shafts, was used. Construct homogenization judgment feature vector .

[0081] The homogenization determination logic is as follows: In continuous Within each sampling period ( For example, a preset positive integer. If conductivity The relative rate of change is always lower than the second preset threshold for the rate of change of conductivity. And the characteristic value of transmittance The relative rate of change is always lower than the second preset transmittance change rate threshold. And the weighted average of the drag torque The relative fluctuation amplitude is always lower than the third preset resistance torque fluctuation threshold. Simultaneously, the acoustic emission instantaneous energy release integral in step 3 It has returned to the preset background baseline value. Chaos degeneration index in step 5 It has stabilized at the preset chaos degradation threshold. Then, the central control unit determines that the material has reached the preset homogenization state and immediately issues a mixing completion signal.

[0082] During the determination process, the central control unit simultaneously monitors the cumulative stirring time. If the cumulative stirring time exceeds the preset maximum stirring time threshold... If the homogenization criteria are still not met, the central control unit will automatically stop stirring and issue an abnormal alarm signal, prompting the operator to perform manual sampling and analysis.

[0083] Once the mixing completion signal is issued, the central control unit initiates the closed-loop discharge procedure. The closed-loop discharge mechanism includes a discharge ball valve with a sealed structure and a negative pressure suction device. Before the discharge ball valve opens, the negative pressure suction device is pre-activated to create a slightly negative pressure environment within the discharge pipeline. Subsequently, the discharge ball valve gradually opens according to a preset opening curve, and the finished water-soluble fertilizer is discharged through the discharge pipeline under the combined action of gravity and negative pressure suction. A mass flow meter is installed at the discharge port to accumulate the mass of the finished product discharged in real time. When the accumulated discharge mass reaches the preset batch target mass, the central control unit automatically closes the discharge ball valve and stops the drive motors of the first and second stirring shafts, completing one full production cycle.

[0084] Step 8: Self-cleaning and zero-loss material recycling; As a further improvement of the present invention, the method further includes a self-cleaning stage after step 7. The central control unit activates the spray ball array installed at the top of the mixing tank. A high-pressure cleaning pump pressurizes and delivers the cleaning liquid (usually process water or a portion of the liquid raw material from the next batch) to the spray ball array, forming an omnidirectional jet covering the inner wall of the mixing tank, the first stirring shaft, the second stirring shaft, the first impeller, and the second impeller. During the cleaning process, the first and second stirring shafts rotate alternately in opposite directions at low speeds, allowing the cleaning jet to reach the back and root areas of the impellers. The waste liquid generated during cleaning is discharged through a discharge mechanism and recycled to a dilution water storage tank as the reference water for the next batch of production, achieving zero material loss and clean production.

[0085] As a further improvement of the present invention, the dual-shaft blades in step 2 are arranged in an asymmetrical configuration. Specifically, the number of first blades mounted on the first stirring shaft is not equal to the number of second blades mounted on the second stirring shaft (for example, the first stirring shaft is configured with...). The first impeller and the second stirring shaft are configured as follows: The second impeller is arranged in a set of two impellers, and there is a slight, pre-set difference between the axial installation spacing between adjacent first impellers and the axial installation spacing between adjacent second impellers. This asymmetric arrangement can physically break the periodic cyclic flow pattern of materials along the axial direction in the mixing tank, forming a spatial-temporal dual chaos enhancement mechanism with the chaotic mixing quantification and transient phase disturbance control in step 5, further suppressing the formation of dead zones in the mixing.

[0086] As a further improvement of the present invention, the particle size monitoring sensor in the sensor array in step 1 also has a particle shape factor recognition function. The central control unit extracts the equivalent projected area and perimeter of the particle from the particle projection image obtained by the particle size monitoring sensor using an image processing algorithm, and calculates the aspect ratio parameter of the particle. When the length-to-diameter ratio of the material Significant deviation When the particles are needle-shaped or sheet-shaped, the central control unit automatically increases the initial rotation speed setting in step 2 to compensate for the orientation resistance of irregularly shaped particles in the flow field.

[0087] As a further improvement of the present invention, the mathematical model of material rheological properties in step 4 also introduces a temperature-viscosity coupling correction term. Because the molecular conformation of some organic components (such as specific amino acids) in soil-improving water-soluble fertilizers is temperature-sensitive, their solution viscosity decreases exponentially with increasing temperature. The mathematical model uses an Arrhenius-type temperature correction factor: For consistency coefficient Real-time corrections are performed, among which For flow activation energy, This is the universal gas constant. Absolute temperature The reference temperature is used. This correction term is applied to the apparent viscosity in step 4. The accurate estimation, thereby improving the Kolmogorov microscale The calculation accuracy.

[0088] As a further improvement of the present invention, both the first and second frequency converters in step 2 have energy feedback functions. When the process requires the first or second stirring shaft to decelerate rapidly, the corresponding first or second drive motor enters a regenerative braking state, and the generated electrical energy is fed back to the factory's internal power grid or energy storage device after being inverted through the DC bus and feedback unit, thereby reducing the overall energy consumption of the system.

[0089] As a further improvement of the present invention, the central control unit also possesses historical data self-learning and parameter self-optimization functions. The central control unit automatically records the frequency curve, drag torque curve, acoustic emission energy release curve, pressure curve, temperature curve, and final homogenization determination time for each production batch throughout the entire process. Through regression analysis and pattern recognition of historical data from multiple batches, the central control unit can automatically correct the output value of the speed mapping table in step 2, the threshold coefficient of the Kolmogorov microscale criterion in step 4, and the chaos degradation threshold in step 5. The set values ​​and the homogenization judgment threshold in step 7 enable the system control performance to be continuously optimized as the number of operating batches increases.

[0090] As a further improvement of the present invention, the method also includes a flexible shear control subroutine for materials containing heat-sensitive active components. When the user selects "Active Protection Mode" through the operating interface, the central control unit restricts the Kolmogorov microscale in step 4. The lower limit value is set (to avoid excessive shearing leading to molecular chain breakage), and the frequency ramp rate is limited to ensure that the maximum shear stress applied to the material is always lower than the critical stress value for molecular chain breakage of the active component. At the same time, the cooling effect of the enhanced condensation recovery unit in step 6 is used to control the material temperature below the denaturation temperature of the active component.

[0091] To facilitate a better understanding of the present invention by those skilled in the art, the present invention will be further illustrated below with reference to specific implementation examples.

[0092] Example 1: In this example, the mixing tank is a vertical cylindrical sealed container made of austenitic stainless steel 316L. The inner wall is electrolytically polished, and the surface roughness is [not specified]. The effective volume is The outer wall of the mixing tank is equipped with an insulation jacket, which can be used to regulate the temperature by introducing preheating or cooling media. The first and second stirring shafts are installed parallel to each other inside the mixing tank, with a center distance of [missing information]. The first stirring shaft is driven by a first drive motor via a first frequency converter, and the second stirring shaft is driven by a second drive motor via a second frequency converter. The rated power of both the first and second drive motors is [missing information]. Both the first and second blades are trapezoidal shear blades, with the blades forming an angle with the axis of rotation. The outer radius of the blade rotation circle is The first stirring shaft is equipped with The first impeller and the second stirring shaft are equipped with The second set of blades consists of adjacent sets of blades arranged alternately in the axial direction. When the first and second stirring shafts rotate, the motion trajectories of the first and second blades form a width of approximately [missing information] in the central region. The overlapping area.

[0093] The sensor array configuration includes: a moisture monitoring sensor (near-infrared, measuring range...) Precision ), installed above the inlet of the sealed conveying unit; particle size monitoring sensor (laser diffraction type, measurement range) repetitive Installed on the side wall of the screw conveyor outlet, and equipped with particle shape factor recognition function; weight monitoring sensor (pressure strain gauge type, range) (Accuracy level C3), arranged at four support points at the bottom of the mixing tank; acoustic emission sensor (resonant type, center frequency...) Operating frequency range Preamplifier gain The device is installed in the corresponding position of the effective stirring area in the middle of the outer wall of the mixing tank using a magnetic clamp. Ultrasonic coupling agent is applied to the mounting surface to ensure acoustic impedance matching. The first and second pressure sensors (diffuse silicon type, range...) Precision ), installed in the gas phase zone at the top of the mixing tank; temperature sensor (platinum resistance type, PT100, measuring range) Precision ), installed on the side wall of the mixing tank in the liquid phase zone.

[0094] The pressure balancing assembly includes: a micro-pressure regulating valve (pneumatic diaphragm type, control range...) ); condensation recovery unit, which includes a first-stage heat exchanger (normal temperature circulating water, heat exchange area) ) and the second-stage heat exchanger (low-temperature refrigerant, ethylene glycol solution, heat exchange area ), return pipeline; air supply valve; and backup pressure relief circuit.

[0095] The online monitoring unit includes: an immersion conductivity probe (graphite electrode type, measurement range...) Precision Near-infrared spectral sensor (wavelength range) Configure diffuse reflection fiber optic probes).

[0096] The central control unit uses a multi-core industrial controller with a real-time operating system, and the sampling period is set to [value missing]. (The acoustic emission channel sampling rate is set to) The central control unit communicates with the first and second frequency converters, various sensors, and actuators via an EtherCAT industrial Ethernet bus. Its internal storage unit contains a database of material hygroscopic characteristics, an Antoine equation parameter library, an Arrhenius correction parameter library, and previously calibrated drag torque-stress conversion coefficients. Blade geometry - overlap zone shear coefficient Model parameters, etc.

[0097] In practical implementation, a typical soil-improving water-soluble fertilizer formula is produced, with the following material formula (by mass percentage): mineral-derived potassium humate powder (purity...) The initial average particle size is approximately The moisture content is approximately ): Industrial grade potassium dihydrogen phosphate (crystals, initial average particle size approximately...) The moisture content is approximately ): ; A mixture of chelated trace elements (chelated zinc, chelated manganese, boric acid, with an initial average particle size of approximately ): Deionized water: .

[0098] Control process: Step 1: The central control unit obtains the moisture content of the potassium humate powder through a moisture monitoring sensor. The average particle size was obtained through a particle size monitoring sensor. The average particle size of potassium dihydrogen phosphate is The average particle size of the trace element mixture is The particle size monitoring sensor simultaneously calculates the particle aspect ratio. Potassium humate powder The mean is (Approximately spherical), potassium dihydrogen phosphate The mean is Based on a pre-set database of material hygroscopic characteristics, the central control unit determines that potassium humate powder will rapidly absorb water and release heat of hydration upon contact with the liquid phase, estimating the wetting behavior parameters as "rapid wetting, moderate heat release." Accordingly, the central control unit sets the screw conveyor feeding rate to its rated rate. The switching cycle of the sealing valve assembly is set to During the feeding process, the bag filter is pre-activated to create a local negative pressure at the feeding port, maintaining the gas phase pressure inside the mixing tank at [value missing]. to Within the range (the first preset pressure threshold is) ).

[0099] Step 2: After feeding is completed, the weight monitoring sensor reports the total mass of the material in the tank. The central control unit queries the speed mapping table and obtains the initial speed setting value: the rated speed of the first stirring shaft. (corresponding motor frequency) Rotation speed approximately ), the rated speed of the second stirring shaft The two axes rotate in the same direction, rapidly establishing a macroscopic circulating flow field. The first and second phase encoders provide real-time feedback of the phase angle, and the central control unit calculates the blade spatial position function, ensuring that the minimum blade clearance within the overlapping area is always greater than [a certain value]. The system's cumulative uptime has reached [amount missing]. At this time, the material has completed initial wetting and macroscopic mixing.

[0100] Step 3: From the first Initially, the central control unit... Sampling frequency continuously acquires acoustic emission sensor signals Using Daubechies-10 wavelet packet pairs conduct Layer decomposition, extraction to Frequency band sub-signal reconstruction Calculate the integral of instantaneous energy release. .exist to period, From the background baseline value approximately Rapidly rises to peak value It then enters the exponential decay phase. The central control unit obtains the decay time constant through fitting. . To the first hour, It has dropped to the background baseline value The duration has reached [number] times, and the duration has reached [number]. The central control unit determines that the brittle fracture clustering process of the hard agglomerates has ended and automatically switches to step 4.

[0101] Step 4: After entering Step 4, the central control unit... Sampling frequency synchronous acquisition , , , , , Waiting for signals. Material equivalent specific heat capacity. Calculated by weighted average of the formula . No. At that time, the calculation yielded , , (Calibration value).

[0102] According to the formula The calculation yields: density Estimated as Effective volume The turbulent energy dissipation rate was calculated as follows: At this point, the two axes rotate in opposite directions, and the average shear rate... . Calibration value , , ,but: The central control unit collected , Calibration value Calculate the apparent viscosity: kinematic viscosity .

[0103] Calculation of Kolmogorov microscale : in, , ,but: Preset target aggregate feature size .at this time This indicates that the microscale of turbulence is insufficient, and the central control unit immediately triggers the thermo-rheological decoupling control subroutine.

[0104] The central control unit reduces the absolute speeds of both the first and second stirring shafts to their original set values. The opening degree of the micro-pressure regulating valve is determined by Increase to Simultaneously, the jacket insulation is closed. Pressure is supplied by... Descending to According to Dalton's law of partial pressures, the deviation of the water vapor partial pressure drives evaporative cooling, and the material temperature is within... From the inside Descending to After the temperature drops, rebounded to , Recalculate Approximately The central control unit restores the rotation speed to the target level and continues shearing and dispersion.

[0105] Throughout step 4, the central control unit continuously executes the aforementioned Kolmogorov-scale targeted closed-loop control until the... , Stable at to Range, and acoustic emission Maintain at the background baseline level.

[0106] Step 5: During the parallel operation in Step 4, the central control unit from the... Simultaneous execution of chaotic hybrid metric quantization. Sliding time window. Continuous calculation and cross-correlation function and its power spectral density . No. At that time, extract respectively and The fundamental frequency and harmonic energy were calculated. Exceeding the preset threshold The central control unit initiates pseudo-random pulse injection: at the... , , At that moment, the injection duration into the second frequency converter is... to Amplitude to Random frequency pulses. After injection Rapidly dropped to The flow field returns to a chaotic mixed state. Subsequently, every... to Perform a pulse injection to ensure there are no blind spots in the entire tank.

[0107] Step 6: Throughout the stirring process, the first and second pressure sensors monitor the pressure inside the tank. When performing thermo-rheological decoupling control, the central control unit actively... Temporarily downgraded to The evaporation cooling rate is controlled by precisely calculating the deviation of the water vapor partial pressure. When the vapor phase temperature reaches... At the same time, through the multi-stage condensation of the micro-pressure regulating valve and the condensation recovery unit, the pressure fluctuation range is controlled within a certain range. to Between, the range is .

[0108] Step 7: From the first From this point on, the online monitoring unit began to continuously collect data. and Sampling period . No. At times, continuously Within each sampling period The relative rate of change is lower than , The relative rate of change is lower than , Volatility lower than Simultaneous acoustic emission It is already at the baseline. Stable at The central control unit determines that homogenization has been achieved and issues a mixing completion signal. At this point, the cumulative mixing time is... .

[0109] Discharge procedure start: negative pressure suction device pre-set Negative pressure in the pipeline, discharge ball valve The initial flow rate is gradually increased to full opening. The finished water-soluble fertilizer is discharged smoothly, and the mass flow meter accumulates the flow until the batch target mass is reached. Afterwards, the discharge ball valve closes, and the first and second drive motors stop.

[0110] Step 8: Automatically enters the self-cleaning stage, the spray ball array... Pressure spray cleaning The cleaning waste liquid is recycled to the dilution water storage tank.

[0111] The water-soluble fertilizer product generated in this embodiment was sampled and tested, and the results are shown in Table 1 below: Table 1: Example 2: This example is used to highlight the differentiated control strategy of the present invention for high-viscosity humic acid materials, especially the synergistic effect of asymmetric blade arrangement and chaotic perturbation enhancement.

[0112] The material formula (by mass percentage) is as follows: High viscosity mineral-derived sodium humate powder (purity) The initial average particle size is approximately The moisture content is approximately ): Amino acid raw powder (compound amino acids, initial average particle size approximately...) ): Potassium sulfate (crystals, initial average particle size approximately...) ): Deionized water: .

[0113] The formulation in this embodiment has a higher sodium humate content, and the addition of amino acid powder further increases the viscosity peak of the system during the middle stage of dissolution.

[0114] The control process is basically the same as in Example 1, except that: In step 2, the central control unit detects that the sodium humate content is higher than the preset high viscosity formulation threshold ( The system automatically invokes the "High Viscosity - Long Cycle Shear" expert database mode. The initial speed setting is adjusted to the rated speed. (Corresponding to the approximation) ( ), to establish a macroscopic flow field in a smoother manner.

[0115] In step 3, due to the high hardness of sodium humate particles, the acoustic emission characteristic frequency band is adjusted to... to . Peak reached decay time constant The time required for hard aggregates to break down is extended to [number missing]. .

[0116] In step 4, when the first hour Because the temperature rise exceeds The central control unit performs asynchronous differential shear and thermo-rheological decoupling joint control. Simultaneously, the central control unit activates the Arrhenius temperature-viscosity coupling correction module to ensure the accuracy of apparent viscosity estimation.

[0117] In step 5, because high-viscosity systems are more prone to forming laminar boundary layers, the chaos degradation threshold... Automatically downgraded to The pulse amplitude range is adjusted to... to To provide stronger flow field disturbance.

[0118] The final homogenization determination time in this embodiment is: The implementation results are shown in Table 2 below: Table 2: Example 3: This example demonstrates the application effect of the activity protection mode of the method of the present invention in the production of heat-sensitive active components; Material formulation (by mass percentage): mineral-derived potassium humate powder (same as in Example 1): Alginic acid extract (containing thermosensitive plant growth stimulants, initially in powder form): Potassium dihydrogen phosphate: Chelated trace element mixture: Deionized water: The active ingredients in alginate extract can be absorbed at temperatures exceeding [a certain temperature range]. They are prone to molecular chain breakage and inactivation when subjected to high shear stress.

[0119] The main differences between the control process and Example 1 are: The operator selects "Active Protection Mode" via the human-machine interface. Based on this, the central control unit imposes the following constraints on the control parameters: In step 2, the initial speed is further reduced to the rated speed. (about The co-directional running time of the two axes has been extended to .

[0120] In step 3, the decay time constant The multiple of the criterion is determined by Adjusted to The high-intensity shearing phase can be ended earlier than expected.

[0121] In step 4, Kolmogorov at the microscale The lower limit is restricted to not less than This prevents excessive shearing that could break the alginate macromolecular chains. Simultaneously, the cooling rate in the thermo-rheological decoupling control subroutine is limited to no more than [a certain value]. .

[0122] In step 6, the refrigerant temperature of the second-stage heat exchanger in the condensation recovery unit is set to... Insulation jacket is inserted Constant temperature cooling water strictly controls the material temperature. the following.

[0123] The final homogenization determination time in this embodiment is: The implementation results are shown in Table 3 below: Table 3: Comparative Example 1: This comparative example uses a conventional constant-speed dual-shaft synchronous stirring method and the same stirring equipment hardware as in Example 1, but does not enable the closed-loop control logic of this invention.

[0124] Control process: The first and second stirring shafts maintain their rated speeds throughout the entire process. (Right now ,about Synchronous reverse rotation. No closed-loop control functions are used, such as acoustic emission sensors, drag torque feedback, Kolmogorov scale calculation, or chaotic mixture quantification. The pressure inside the tank is passively released only through a mechanical safety valve, with a set start-up pressure of [value missing]. There is no condensation recovery unit. The stirring time is set to a fixed value. .

[0125] The implementation results are shown in Table 4. Comparative Example 2: This comparative example uses a conventional single-shaft central stirring method, with the single shaft operating at a constant speed. Continuous rotation. Implementation effect data ( (Sampling at time) The implementation results are shown in Table 5. Table 5: Table 6 summarizes the comparison of the effects of the examples and comparative examples: Table 6: Table 1 clearly shows that Examples 1-3 are significantly superior to Comparative Examples 1 and 2 in all key performance indicators. Example 1 has a shorter homogenization time than Comparative Example 1 by approximately [missing data]. The average particle size decreased by approximately Energy consumption per unit is reduced by approximately Increased activity retention The percentage point difference is more significant than that of Comparative Example 2. Example 2 verifies the advantages of asymmetric structure and chaotic perturbation in high-viscosity formulations; Example 3 verifies that the active protection mode effectively protects the heat-sensitive components with a slight sacrifice in efficiency.

[0126] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0127] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for efficient mixing and dispersion control of water-soluble fertilizer using a closed-loop biaxial paddle system for soil improvement, characterized in that: The method includes the following steps: Step 1: The initial physical parameters of the raw materials are synchronously collected through the sensor array. The central control unit estimates the wetting behavior parameters based on this and controls the closed and controlled feeding. Step 2: The central control unit drives the first and second stirring shafts to run at the initial speed through the first and second frequency converters to establish a macroscopic circulating flow field; Step 3: Perform tracking and determination of the micro-fracture process of solid hard agglomerates based on acoustic emission spectrum characteristics. When the brittle fracture clustering process of solid hard agglomerates is determined to be over, step 4 is automatically triggered. Step 4: Perform adaptive optimization of power dissipation and Kolmogorov microscale targeted control under strong thermo-rheological coupling. The Kolmogorov microscale is calculated in real time by stripping the effective mechanical dissipation power, and the rotation speed and tank pressure are dynamically adjusted according to the comparison results of the Kolmogorov microscale and the characteristic size of the target aggregate. Step 5: Simultaneously execute spatial chaotic mixing quantification and dual-axis transient phase perturbation control, use chaotic degradation index to quantify the degree of periodic degradation of the flow field in real time, and inject non-periodic pseudo-random pulses to disrupt the laminar boundary layer; Step 6: Implement active compensation for pressure fluctuations in the closed environment and coordinated control of latent heat of vaporization based on Dalton's law of partial pressures to decompose the total pressure inside the tank into water vapor partial pressure and non-condensable gas partial pressure. Cooling and pressure balance are achieved by adjusting the water vapor partial pressure. Step 7: Determine the dispersion endpoint based on the multi-parameter fusion homogenization judgment logic, and execute intelligent closed material discharge.

2. The method for efficient mixing and dispersion control of water-soluble fertilizer with closed biaxial paddles for soil improvement according to claim 1, characterized in that, The microscopic fragmentation tracking logic based on acoustic emission spectrum characteristics in step 3 includes: the central control unit acquires the full-band acoustic emission signal in real time, extracts the characteristic high-frequency band signal from 100 kHz to 500 kHz using wavelet packet transform, and reconstructs it to obtain the high-frequency acoustic emission reconstructed signal; calculates the instantaneous energy release integral within the characteristic high-frequency band, wherein the instantaneous energy release integral is equal to the definite integral of the square of the modulus of the short-time Fourier transform spectrum of the high-frequency acoustic emission reconstructed signal between the lower limit frequency and the upper limit frequency of the characteristic high-frequency band.

3. The method for efficient mixing and dispersion control of water-soluble fertilizer with closed biaxial paddles for soil improvement according to claim 2, characterized in that, The criterion for determining the end of solid-phase hard agglomerate fragmentation in step 3 is as follows: the central control unit defines the time derivative of the instantaneous energy release integral as the acoustic emission event occurrence rate index, and after the instantaneous energy release integral enters the exponential decay period, the decay time constant is extracted by fitting an exponential decay model. The exponential decay model is the instantaneous energy release integral equal to the initial decay amplitude multiplied by an exponential function of the ratio of negative time to decay time constant with the natural constant e as the base, plus the background noise baseline value; when the instantaneous energy release integral drops to within 1.2 times the preset background baseline value and lasts for more than three times the decay time constant, the physical fragmentation of the hard agglomerate is determined to be over.

4. The method for efficient mixing and dispersion control of water-soluble fertilizer with closed biaxial paddles for soil improvement according to claim 1, characterized in that, The method for stripping the effective mechanical dissipation power in step 4 is as follows: the effective mechanical dissipation power is equal to the total input electrical power minus the product of the material's equivalent specific heat capacity, the material's cumulative total mass, and the material's temperature's first time derivative, and then minus the equipment's fixed loss power.

5. The method for efficient mixing and dispersion control of water-soluble fertilizer with closed biaxial paddles for soil improvement according to claim 4, characterized in that, The calculation logic of the Kolmogorov microscale in step 4 is as follows: the turbulent energy dissipation rate is calculated based on the effective mechanical dissipation power. The turbulent energy dissipation rate is equal to the effective mechanical dissipation power divided by the product of the current material density and the effective mixing volume. The effective mixing volume is equal to the cumulative total mass of the material divided by the current material density. The apparent viscosity of the material is estimated in real time by combining the resistance torque feedback values ​​of the first and second stirring shafts, and the kinematic viscosity is calculated. The kinematic viscosity is equal to the apparent viscosity of the material divided by the current material density. The Kolmogorov microscale is calculated to be equal to the cube of the kinematic viscosity and the quarter power of the ratio of the turbulent energy dissipation rate.

6. The method for efficient mixing and dispersion control of water-soluble fertilizer with closed biaxial paddles for soil improvement according to claim 5, characterized in that, The estimation of apparent viscosity in step 4 involves determining the average shear rate of the overlapping region: when the first and second stirring shafts rotate in the same direction, the average shear rate of the overlapping region is equal to the blade geometry minus the shear coefficient of the overlapping region multiplied by the absolute value of the difference between the rotational speeds of the first and second stirring shafts; when the first and second stirring shafts rotate in opposite directions, the average shear rate of the overlapping region is equal to the blade geometry minus the shear coefficient of the overlapping region multiplied by the sum of the rotational speeds of the first and second stirring shafts; the apparent viscosity of the material is equal to the sum of the resistance torque feedback values ​​of the first and second stirring shafts divided by the product of the resistance torque-stress conversion coefficient and the average shear rate of the overlapping region.

7. The method for efficient mixing and dispersion control of water-soluble fertilizer with closed biaxial paddles for soil improvement according to claim 5, characterized in that, The targeted closed-loop control strategy in step 4 includes: the central control unit presets the target agglomerate characteristic size; when the Kolmogorov microscale is greater than or equal to the target agglomerate characteristic size, the thermo-rheological decoupling control subroutine is triggered, reducing the absolute speed of the first and second stirring shafts to 60% to 80% of the set value, and simultaneously increasing the opening of the micro-pressure regulating valve, using the pressure reduction in the sealed tank to promote the absorption of latent heat of water evaporation, until the Kolmogorov microscale is smaller than the target agglomerate characteristic size.

8. The method for efficient mixing and dispersion control of water-soluble fertilizer with closed biaxial paddles for soil improvement according to claim 1, characterized in that, The quantification method for the chaotic degradation index in step 5 is as follows: extract the power spectral density of the cross-correlation function between the resistance torque feedback value of the first stirring shaft and the resistance torque feedback value of the second stirring shaft. The chaos degradation index is calculated based on the rotational frequencies of the first and second stirring shafts and their respective first N harmonic amplitudes. The chaos degradation index is equal to the sum of the power spectral density amplitudes corresponding to the first N harmonics of the first stirring shaft rotational frequency and the sum of the power spectral density amplitudes corresponding to the first N harmonics of the second stirring shaft rotational frequency, divided by the integral of the power spectral density in the range from zero to the Nyquist frequency. When the chaos degradation index is greater than or equal to a preset chaos degradation threshold, it is determined that the flow field has periodic degradation, where N is the preset harmonic number and takes a positive integer value.

9. The method for efficient mixing and dispersion control of water-soluble fertilizer with closed biaxial paddles for soil improvement according to claim 8, characterized in that, The phase disturbance in step 5 is achieved by generating a pseudo-random binary sequence to control the second frequency converter, injecting a duration... for to Amplitude For the current frequency to The random frequency pulse correction amount.

10. The method for efficient mixing and dispersion control of water-soluble fertilizer with closed biaxial paddles for soil improvement according to claim 1, characterized in that, Water vapor partial pressure in step 6 The stripping logic is as follows: The central control unit calibrates the partial pressure of noncondensable gases based on initial static conditions. ; The current water vapor partial pressure is calculated in real time during the stirring process. ; in, This represents the total pressure inside the tank in the initial state; This represents the partial pressure of water vapor in the initial state; This indicates the current absolute temperature of the gas phase; This represents the absolute temperature of the gas phase in its initial state.

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