A production process control method of humic acid chelated zinc compound fertilizer particles

Abstract

The present application belongs to the technical field of compound fertilizer production control, and relates to a production process control method of humic acid chelated zinc compound fertilizer particles. The present application allocates the total amount of zinc source to each monitoring period according to a non-linear decreasing strategy, establishes the addition rate, and reversely corrects the subsequent addition rate in combination with the chelation rate change rate. The chelation rate change rate and the coupling coefficient of temperature-chelation rate are calculated in real time, and the criterion is used to dynamically execute the temperature and speed reduction, speed increase, pulse stirring and stepwise temperature increase cooperative activation mode. When the chelation rate change rate continuously converges, the coupling coefficient maintains positive correlation, and the zinc source addition is completed, the reaction termination condition is determined by multi-index joint determination. The present application solves the problems of mismatching between zinc source addition and reaction progress, difficulty in restoring reaction efficiency by single parameter adjustment, and lag in reaction endpoint judgment in the existing process, realizes the dynamic balance between zinc source supply and chelation capacity, and ensures the stability of the product chelation rate.

Description

Technical Field

[0001] This invention belongs to the field of compound fertilizer production control technology, and relates to a production process control method for compound fertilizer granules containing humic acid chelated zinc. Background Technology

[0002] The production of humic acid chelated zinc compound fertilizer typically employs a liquid-phase chelation reaction followed by granulation. This involves a chemical reaction between humic acid and zinc ions in an aqueous system to generate a stable chelated product, which is then granulated into granular compound fertilizer. In current production processes, the zinc source is often added manually at a fixed rate, either all at once or in batches. The reaction temperature and stirring speed are either set as constant values ​​based on experience or manually adjusted by operators based on offline monitoring of free zinc ion concentration.

[0003] Chelation is a nonlinear process involving multiple variables. In the initial stage of the reaction, the zinc ion concentration is high, leading to a rapid chelation rate. However, excessive concentration in certain areas can easily cause the accumulation of free zinc. In the later stages, the number of active sites decreases, resulting in insufficient chelation kinetics. A fixed addition rate is difficult to match the dynamic changes in the zinc source demand during the reaction process. In the initial stage, excessive zinc addition is likely, while in the later stages, insufficient zinc supply leads to incomplete chelation.

[0004] Meanwhile, reaction temperature and stirring conditions have a complex interactive effect on the chelation reaction process. Increased temperature can accelerate molecular diffusion and reaction kinetics, but excessively high temperatures can destroy the stability of the humic acid colloidal structure. Insufficient stirring intensity leads to uneven mixing, while excessive stirring intensity may introduce excessive shear force, affecting the chelation equilibrium. In practice, temperature and stirring parameters are often set independently. When the reactivity decreases, adjusting a single parameter alone is often insufficient to effectively restore reaction efficiency, resulting in prolonged reaction cycle or the product chelation rate not meeting expectations.

[0005] In addition, the determination of the endpoint of the chelation reaction is mostly based on a fixed reaction time or manual sampling to detect the concentration of free zinc ions. Due to the complex source of humic acid and the large difference in activity between batches, it is difficult to ensure the consistency of the chelation rate of each batch of products under fixed process conditions. Manual sampling has a lag and cannot determine the termination time in real time during the reaction process, resulting in uneven chelation state at the end of the reaction, and the stability of the material entering the granulation process is difficult to guarantee. Summary of the Invention

[0006] In view of this, in order to solve the problems mentioned in the background art, a production process control method for humic acid chelated zinc compound fertilizer granules is proposed.

[0007] The objective of this invention can be achieved through the following technical solution: a production process control method for humic acid chelated zinc compound fertilizer granules, comprising: S1, allocating the total amount of zinc source to each monitoring cycle according to a non-linear decreasing strategy, and establishing the injection acceleration rate for each monitoring cycle.

[0008] S2. Add zinc source according to the acceleration rate, calculate the chelation rate change rate and temperature-chelation rate coupling coefficient in real time, and perform the following control.

[0009] S21. If the coupling coefficient is negatively correlated, then the cooling and stirring speed reduction regulation is triggered until the correlation returns to positive. If the rate of change of chelation rate decreases, then the stirring speed is increased. If the rate of change of chelation rate continues to decrease or converges after the increase, then the pulse stirring and step heating synergistic activation mode is triggered.

[0010] S22. Based on the rate of change of chelation rate and the acceleration rate of injection in the current monitoring period, the acceleration rate of injection in the next monitoring period is corrected in reverse.

[0011] S3. When the rate of change of chelation rate continues to converge, the coupling coefficient remains positively correlated, and the zinc source is completely added, the reaction termination condition is determined to be met, the chelation reaction is terminated, and the product is output to the granulation process.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention establishes the acceleration rate by allocating the total amount of zinc source to each monitoring cycle according to a nonlinear decreasing strategy, and combines the chelation rate change rate with the acceleration rate to correct the subsequent acceleration rate in a closed loop. This solves the problem that the existing static addition method is difficult to match the reaction process, which is prone to overload in the early stage and insufficient power in the later stage. This makes the zinc source supply curve fit the consumption trend of humic acid active sites, avoids the local excess accumulation of free zinc and the raw material supply interruption at the end of the reaction, and realizes the dynamic balance between zinc source addition and real-time chelation capacity.

[0013] (2) This invention calculates the temperature-chelation rate coupling coefficient and the chelation rate change rate in real time, and dynamically executes cooling and speed reduction, speed increase, or triggering pulse stirring and step heating to activate the reaction in synergy based on the criteria. This solves the problem that it is difficult to effectively restore the reaction efficiency by adjusting a single parameter, and realizes the synergistic control of temperature and stirring. When the reaction kinetics decay, it can adaptively enhance mass transfer and energy input to maintain the efficient operation of the chelation reaction.

[0014] (3) This invention constructs a termination trigger condition based on the joint monitoring of the convergence of the chelation rate change rate, the positive correlation of the coupling coefficient, and the completion status of zinc source addition. This solves the problems of fixed-duration processes being unable to adapt to batch differences in raw materials and the lag in offline detection, and achieves accurate identification of the reaction endpoint and automatic shutdown, ensuring the consistency of the chelation rate of each batch of products and providing stable materials for the granulation process. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart of a production process control method for humic acid chelated zinc compound fertilizer granules according to the present invention.

[0017] Figure 2 This is a flowchart of the method for calculating the rate of change of chelation rate in this invention;

[0018] Figure 3 This is a flowchart illustrating the specific content of S21 in this invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0021] The following describes in detail, with reference to the accompanying drawings, a specific scheme for the production process control method of humic acid chelated zinc compound fertilizer granules provided by the present invention.

[0022] Please see Figure 1 As shown, the implementation of the present invention includes S1 to S3: In the production process of humic acid chelated zinc compound fertilizer granules, the liquid-phase chelation reaction of humic acid and zinc source is a complex chemical process that is dynamically affected by the viscosity, temperature and mass transfer conditions of the system. However, the traditional zinc source addition method is mostly static, which can easily lead to local zinc ion concentration overload and trigger side reactions; the mass and heat transfer of the system is limited in the middle and late stages of the reaction, which can easily lead to reaction kinetic decay; and there is a lack of adaptive endpoint criteria that match the reaction state, which can easily cause insufficient or excessive reaction. In order to solve the above problems, a control method based on periodic monitoring and feedback regulation is proposed.

[0023] S1 is used to solve the problem of mismatch between the initial distribution of zinc source and reaction kinetics. By distributing the total amount of zinc source to each monitoring cycle according to a nonlinear decreasing strategy, it achieves a refined addition that matches the high activity in the early stage of the reaction and the saturation characteristics in the later stage.

[0024] S2 is used to solve the problems of reduced chelation efficiency and control lag caused by state fluctuations during the reaction process. By calculating the coupling coefficient of temperature-chelation rate and the rate of change of chelation rate in real time, an adaptive adjustment criterion is constructed. Based on the criterion results, the temperature and speed reduction, speed increase or pulse stirring and step heating co-activation mode are dynamically executed to achieve dynamic closed-loop correction of stirring, temperature and acceleration rate.

[0025] S3 is used to solve the problem of incomplete reaction or energy waste caused by traditional fixed-duration determination. By jointly monitoring the convergence of the chelation rate change rate, the positive correlation of the coupling coefficient, and the completion status of zinc source addition, a termination trigger condition for multi-index joint determination is constructed to achieve accurate identification of the reaction endpoint and automatic shutdown.

[0026] This leads to a stable production process control method with the capabilities of reaction kinetic matching, multi-parameter coupling feedback, and intelligent endpoint determination.

[0027] S1. Allocate the total zinc source to each monitoring period according to a non-linear decreasing strategy, and establish the injection acceleration rate for each monitoring period.

[0028] Considering that the chelation reaction between humic acid and zinc source is limited by system mass transfer and reaction kinetics, high concentration addition in the early stage can easily lead to local zinc ion excess and trigger side reactions. Furthermore, the volume of the reactor directly determines the time constraint for uniform mixing. An improper addition strategy will severely affect subsequent chelation efficiency and product quality. Therefore, by allocating the total amount of zinc source to each monitoring cycle according to a non-linear decreasing strategy, and combining the reactor volume and maximum reaction time, the precise addition rate for each monitoring cycle was calculated and established.

[0029] In one specific embodiment, the monitoring cycle is first determined based on the geometry and stirring characteristics of the reactor. Since the uniformity of mixing between the humic acid solution and the zinc source solution in the chelation reaction system directly affects the reaction rate and chelation efficiency, uneven mixing can lead to localized zinc ion overload or reactant concentration gradients, thereby interfering with the accurate monitoring of the subsequent chelation rate.

[0030] Therefore, based on fluid mechanics principles, fluid simulation was performed using the reactor volume, impeller type, and stirring speed to calibrate the time interval required for the system to achieve uniform mixing. This time interval was then used as the duration of a single monitoring cycle. Subsequently, the maximum reaction time was divided by this cycle duration and rounded up to obtain the total number of monitoring cycles, ensuring that the entire reaction process was fully covered without any blind spots in control.

[0031] Based on the reaction kinetics, in the early stage of the reaction, there are sufficient active sites of humic acid, the chelation reaction rate is relatively fast, and the demand for zinc source is large. As the reaction proceeds, the number of unreacted active sites gradually decreases. Excessive addition of zinc source not only wastes raw materials, but may also inhibit the chelation reaction equilibrium due to excessively high concentration of free zinc ions.

[0032] Therefore, a nonlinear decreasing function, such as an exponential decay function, is constructed to make the injection acceleration rate decrease with increasing monitoring cycle number, resulting in unequal differences in the injection acceleration rates between adjacent monitoring cycles. The total zinc source is then substituted into the nonlinear decreasing function to calculate the injection acceleration rate for each monitoring cycle.

[0033] Because the analytical calculation and rounding up of the nonlinear decreasing function may introduce cumulative errors, there will be a deviation between the theoretical total obtained by accumulating the injection rates of each cycle and the actual total amount of zinc source. If the absolute value of this deviation is greater than or equal to the preset allowable error value, it indicates that the allocation result does not meet the total accuracy requirements and error compensation is required. In this case, the difference is evenly distributed to the injection rates of each monitoring cycle so that the theoretical total equals the total amount of zinc source, thereby ensuring the accuracy of zinc source injection and material balance.

[0034] The preset allowable error value can be set according to the production accuracy requirements, for example, it can be set to 0.5% to 1% of the total zinc source.

[0035] To ensure the effective implementation of the above-mentioned acceleration rate allocation scheme, initial operating conditions need to be established before the reaction starts. Therefore, the initial pH and initial temperature of the chelation reaction system are collected before startup. The initial temperature plus a preset temperature rise offset is used as the initial target temperature of the heating system, allowing the system to quickly pass through the preheating stage and avoiding a low initial reaction rate due to an excessively long heating process.

[0036] The preset temperature rise bias can be determined through thermal inertia tests of the reaction system, for example, it can be set to 5℃ to 10℃.

[0037] Furthermore, the required shear mixing strength varies depending on the viscosity and ionization state of the humic acid solution at different pH values. When the initial pH is low, free zinc ions easily form an acidic microenvironment locally, requiring a higher rotation speed to enhance mixing and suppress side reactions. When the initial pH is high, the initial rotation speed can be appropriately reduced to save energy. Therefore, the initial rotation speed of the stirring system should be determined based on the initial pH value. For example, when the initial pH is below 5.0, the initial rotation speed should be set to 80%–100% of the rated speed to enhance mixing and suppress side reactions caused by the local acidic microenvironment; when the initial pH is between 5.0 and 7.0, it should be set to 60%–80% of the rated speed; and when the initial pH is above 7.0, it should be set to 50%–60% of the rated speed to save energy while ensuring mixing effectiveness.

[0038] After completing the above settings, start the stirring and heating system to ensure the reaction system operates stably under initial conditions.

[0039] S2. Add zinc source according to the addition acceleration rate, calculate the chelation rate change rate and temperature-chelation rate coupling coefficient in real time, and perform differentiated control.

[0040] The chelation reaction of humic acid with a zinc source is a dynamic endothermic-exothermic equilibrium process. Temperature changes not only affect the reaction rate but also indirectly affect mass transfer efficiency by altering the system viscosity. Furthermore, continuous addition of the zinc source introduces concentration deviations. Relying solely on static ring-opening addition will cause the system to deviate from the optimal reaction range, failing to guarantee the efficient conduct of the chelation reaction.

[0041] Therefore, by collecting the concentration and temperature of free zinc ions in real time during the dosing process, the coupling coefficient between the rate of change of chelation rate and temperature-chelation rate is calculated. Based on the calculation results, the system can implement regulation by cooling and speed reduction, increasing rotation speed, or pulse stirring and step heating synergistic activation mode, while simultaneously correcting the dosing acceleration rate for the next monitoring cycle.

[0042] In one specific embodiment, please refer to Figure 2 As shown, the calculation steps for the chelation rate change rate are as follows: S101, in each monitoring cycle, the free zinc ion concentration of the chelation reaction system is collected once every preset sampling time interval, for example, 30 to 60 seconds, by means of an online ion selective electrode method.

[0043] S102. Multiply the volume of the chelation reaction system by the concentration of free zinc ions at the current sampling time to obtain the current amount of free zinc. Calculate the current amount of chelated zinc based on the difference between the cumulative total amount of zinc source added and the current amount of free zinc. This calculation assumes that during the reaction, the zinc source exists mainly in two forms: free zinc ions and chelated zinc, ignoring other intermediate or precipitated zinc states.

[0044] The ratio of the current amount of chelated zinc to the cumulative total amount of zinc source added is used as the chelation rate at the current moment. This ratio eliminates the base effect caused by changes in the total amount added and directly reflects the reaction conversion efficiency.

[0045] S103. Subtract the chelation rate from the previous sampling time from the current chelation rate, and divide the difference by the sampling time interval to obtain the rate of change of the chelation rate. This rate of change of the chelation rate represents the increment of the chelation rate per unit time, directly reflecting the current rate of reaction. When this rate is large, it indicates that the reaction is active and the zinc source utilization rate is high; when the rate decreases or approaches zero, it indicates that the reaction kinetics are insufficient or tending to equilibrium, and intervention through regulation is required.

[0046] Furthermore, to distinguish whether the cause of reaction rate decay is mass transfer limitation or thermal inhibition, it is necessary to establish a correlation index between temperature and the rate of change of chelation rate to quantify the thermodynamic and kinetic coordination state of the system. Therefore, the method for calculating the temperature-chelation rate coupling coefficient is as follows: The temperature value and the corresponding rate of change of chelation rate at each sampling time within the current monitoring period are used to form a temperature data sequence and a rate data sequence. The ratio of the product of the covariance of the two sequences and their respective standard deviations is calculated, i.e., the Pearson correlation coefficient. This ratio is then used as the temperature-chelation rate coupling coefficient.

[0047] In a normal chelation reaction, an appropriate increase in temperature usually promotes an increase in the reaction rate, and the two should show a positive correlation, at which point the coupling coefficient is positive. If the coupling coefficient is negative, it indicates that an increase in temperature leads to a decrease in the reaction rate, or a decrease in temperature leads to an increase in the reaction rate. This indicates that the system has experienced abnormal conditions such as thermal inhibition, local overheating leading to destruction of the humic acid structure, or mass transfer failure.

[0048] Based on the chelation rate change rate and coupling coefficient calculated above, the control system identifies the reaction state and executes the following control steps according to the identification results: S21, if the coupling coefficient is negatively correlated, then the cooling and stirring speed reduction control is triggered until it returns to a positive correlation; if the chelation rate change rate decreases, then the stirring speed is increased; if the chelation rate change rate continues to decrease or converges after the increase, then the pulse stirring and step heating synergistic activation mode is triggered.

[0049] When the coupling coefficient is negatively correlated, the temperature increase has already inhibited the chelation reaction; further heating will lead to a decrease in reaction efficiency or even an aggravation of side reactions. Conversely, when the rate of change of the chelation rate decreases, it indicates insufficient mixing of reactants or insufficient activation energy supply, requiring compensation through enhanced mixing or energy input. Therefore, this step employs a graded control mechanism, sequentially executing control operations such as cooling and rate reduction, rotation speed increase, pulse stirring, and step-by-step temperature increase for synergistic activation based on the real-time status of the coupling coefficient and the rate of change of the chelation rate.

[0050] In one specific embodiment, please refer to Figure 3 As shown, the specific steps of S21 are as follows: S201, compare the coupling coefficient of the current monitoring cycle with the zero value. If the coefficient is less than zero, it indicates that the temperature change is negatively correlated with the chelation reaction rate change. That is, the current temperature increase leads to a decrease in the reaction rate, and the system is in a thermally inhibited state.

[0051] To eliminate this abnormal state, the heating system is controlled to reduce the temperature of the chelation reaction system by a temperature step value, and the stirring system's rotation speed is controlled to reduce by a rotation speed percentage. This operation is repeated until the coupling coefficient is greater than or equal to zero. For example, the temperature step value can be set to 1°C to 2°C, and the rotation speed percentage can be set to 5% to 10%.

[0052] S202. After the coupling coefficient is positively correlated, in order to further evaluate whether the reaction motive force is sufficient, the rate of change of chelation rate in the current monitoring period is compared with the rate of change of chelation rate in the previous monitoring period. If the current value is less than the value in the previous period, it indicates that the chelation reaction rate is decaying and the reaction motive force is insufficient, and it is judged to be in a decreasing state.

[0053] To compensate for this attenuation, the stirring system is controlled to increase the stirring speed by a percentage; for example, the speed increase can be set to 5%, which promotes the contact between zinc ions and the active sites of humic acid by enhancing the degree of liquid phase turbulence.

[0054] S203. If, after increasing the stirring speed, the rate of change of chelation rate decreases cycle by cycle for three consecutive monitoring periods (i.e., the rate of change of chelation rate in each cycle is less than that in the previous cycle), or the rate of change of chelation rate is less than the preset rate convergence value, it indicates that conventional stirring enhancement methods can no longer improve the reaction stagnation state, and the system may have entered the kinetic equilibrium restriction region. For example, the preset rate convergence value can be set to 0.005 / min to 0.01 / min; when the rate is lower than this value, the reaction is considered to be tending to stand still.

[0055] To break the reaction equilibrium and activate remaining active sites, the stirring system is controlled to operate in a pulse pattern alternating between forward rotation for a first duration, a stop for a second duration, reverse rotation for a first duration, and a stop for a second duration. The heating system is also controlled to progressively increase the reaction system temperature according to a temperature level sequence, maintaining each temperature level for a third duration. For example, the first duration could be set to 30 seconds, and the second duration to 10 seconds. The shear force generated by the alternating forward and reverse rotation disrupts the local concentration boundary layer.

[0056] The method for obtaining the temperature level sequence is as follows: based on the initial temperature value and the preset temperature rise offset, a temperature level sequence containing multiple temperature level values ​​is generated sequentially according to an arithmetic progression. For example, if the initial temperature is 50℃ and the temperature rise offset is 5℃, the temperature level sequence can be 55℃, 60℃, and 65℃, thereby reducing the impact of temperature abrupt changes on the reaction system through stepwise heating.

[0057] To further avoid overactivation leading to energy waste or side reactions, and to enable the control mode to adaptively return to the normal control state, the activation mode of pulse stirring and step heating is further enhanced by continuously monitoring the rate of change of chelation rate. If the rate of change of chelation rate increases for two consecutive monitoring cycles, it indicates that the reaction system has recovered its kinetic activity. In this case, the activation mode is exited, and the process returns to step S21, so that the control mode adaptively returns to the normal control state.

[0058] S22. Based on the rate of change of chelation rate and the acceleration rate of injection in the current monitoring period, the acceleration rate of injection in the next monitoring period is corrected in reverse.

[0059] Since the acceleration rate is generated based on a nonlinear decreasing function, which is an open-loop allocation method, it cannot perfectly match the fluctuations of the actual reaction process. Therefore, it is necessary to use the real-time observed rate of change of chelation rate to perform closed-loop correction of the acceleration rate, so as to maintain a dynamic balance between the zinc source supply and the actual chelation rate. To this end, this step uses a feedback control method to adjust the acceleration rate.

[0060] In one specific embodiment, firstly, the ratio of the chelation rate change rate to the addition acceleration rate during the current monitoring period is calculated, and this ratio is defined as the chelation efficiency index per unit addition acceleration rate. This index characterizes the increase in chelation rate achievable with the current addition of a unit mass of zinc source. To maintain the stability of the addition efficiency, the calculated chelation efficiency index is compared with a preset target efficiency to obtain the efficiency deviation. The preset target efficiency can be set based on historically optimal process parameters, for example, it can be set to 0.05 to 0.2.

[0061] To eliminate the impact of accumulated errors on long-term control accuracy, if the current monitoring cycle is the initial monitoring cycle, the efficiency deviation of the current monitoring cycle is used as the accumulated deviation value; otherwise, the efficiency deviation of the current monitoring cycle is added to the accumulated deviation value of the previous monitoring cycle to obtain the accumulated deviation value of the current monitoring cycle.

[0062] Subsequently, the rate correction is calculated based on the proportional-integral control principle. The efficiency deviation of the current monitoring cycle is multiplied by a preset proportional coefficient to obtain the proportional term, and the cumulative deviation of the current monitoring cycle is multiplied by a preset integral coefficient to obtain the integral term. The proportional and integral terms are then added together to obtain the rate correction. The preset proportional and integral coefficients can be obtained through process testing. For example, the proportional coefficient can be set to 0.1 to 0.5, and the integral coefficient to 0.01 to 0.05.

[0063] Finally, the rate correction is added to the injection acceleration rate of the current monitoring cycle to obtain the injection acceleration rate of the next monitoring cycle, and the injection acceleration rate of the next monitoring cycle is written into the control system register to guide the zinc source injection operation in the next monitoring cycle.

[0064] S3. When the rate of change of chelation rate continues to converge, the coupling coefficient remains positively correlated, and the zinc source is completely added, the reaction termination condition is determined to be met, the chelation reaction is terminated, and the product is output to the granulation process.

[0065] Considering that excessive reaction not only wastes energy and time but may also cause damage to the humic acid structure or side reactions, and that unreacted free zinc, if not controlled, will directly affect the quality and agricultural safety of compound fertilizer granules, this step automatically triggers reaction shutdown and material transfer when all three conditions are met simultaneously by monitoring the convergence state of the chelation rate change rate, the maintenance of the positive correlation of the coupling coefficient, and the residual state of the zinc source addition.

[0066] In one specific embodiment, the rate of change of chelation rate and coupling coefficient are monitored in real time for each monitoring period.

[0067] When the absolute value of the chelation rate change rate for three consecutive monitoring cycles is less than the preset rate convergence value, and the coupling coefficient of each corresponding cycle is greater than zero, and the absolute value of the difference between the cumulative zinc source addition and the total zinc source is less than the preset allowable error value, it indicates that the reaction system has reached a kinetic equilibrium state, the thermodynamic relationship is normal, and the material addition is completed, and the reaction termination condition is met.

[0068] To prevent the molecular chains of the generated chelate products from breaking due to local residual heat or continuous stirring during the retention process, and to ensure that the material is transferred without obstruction under optimal flow conditions, the heating system and stirring system are shut off and the discharge valve is opened after the termination conditions are met, so that the chelate products in the reactor can be transported to the granulation process, thus achieving continuous connection of the production process.

[0069] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0070] Those skilled in the art will recognize that the algorithmic steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this application.

[0071] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0072] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0073] Finally, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., 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 controlling the production process of humic acid-chelated zinc compound fertilizer granules, characterized in that, include: S1. Allocate the total amount of zinc source to each monitoring period according to a non-linear decreasing strategy, and establish the injection acceleration rate for each monitoring period; S2. Based on the zinc source addition rate, calculate the chelation rate change rate and the temperature-chelation rate coupling coefficient in real time, and implement the following adjustments: S21. If the coupling coefficient is negatively correlated, then the cooling and stirring speed reduction regulation is triggered until the correlation returns to positive. If the rate of change of chelation rate decreases, then the stirring speed is increased. If the rate of change of chelation rate continues to decrease or converges after the increase, then the pulse stirring and step heating synergistic activation mode is triggered. S22. Based on the rate of change of chelation rate and the acceleration rate of injection in the current monitoring period, the acceleration rate of injection in the next monitoring period is corrected in reverse. S3. When the rate of change of chelation rate continues to converge, the coupling coefficient remains positively correlated, and the zinc source is completely added, the reaction termination condition is determined to be met, the chelation reaction is terminated, and the product is output to the granulation process.

2. The production process control method for humic acid chelated zinc compound fertilizer granules as described in claim 1, characterized in that, Step S1 specifically includes: The time interval required for the chelation system to be mixed evenly is determined based on the reactor volume and used as the duration of a single monitoring cycle. Divide the maximum response time by the duration of a single monitoring cycle, and round the resulting quotient up to obtain the total number of monitoring cycles. A nonlinear decreasing function is established that the injection acceleration rate decreases as the monitoring cycle number increases. The total amount of zinc source is substituted into the nonlinear decreasing function to calculate the injection acceleration rate corresponding to each monitoring cycle. The theoretical total is obtained by summing up the acceleration rates of all monitoring cycles. If the absolute value of the difference between the theoretical total and the total zinc source is greater than or equal to the preset allowable error value, the difference is evenly distributed to the acceleration rate of each monitoring cycle.

3. The production process control method for humic acid chelated zinc compound fertilizer granules as described in claim 2, characterized in that, Step S1 also includes: The initial pH and initial temperature of the chelation reaction system were collected; The initial temperature plus the preset temperature rise offset is used as the initial target temperature of the heating system. The initial speed of the stirring system is determined according to the initial pH value, and the stirring and heating systems are started.

4. The production process control method for humic acid chelated zinc compound fertilizer granules as described in claim 1, characterized in that, The method for calculating the rate of change of the chelation rate is as follows: Within each monitoring cycle, the concentration of free zinc ions in the chelation reaction system is collected once at a preset sampling time interval; The current amount of free zinc is obtained by multiplying the volume of the chelation reaction system by the concentration of free zinc ions at the current sampling time. The current amount of chelated zinc is calculated based on the difference between the total amount of zinc source added and the current amount of free zinc. The ratio of the current amount of chelated zinc to the total amount of zinc source added is taken as the chelation rate at the current time. The rate of change of chelation rate is obtained by subtracting the chelation rate at the previous sampling time from the chelation rate at the current time and dividing the difference by the sampling time interval.

5. The production process control method for humic acid chelated zinc compound fertilizer granules as described in claim 1, characterized in that, The method for calculating the temperature-chelation rate coupling coefficient is as follows: The temperature data sequence and the rate data sequence are formed by combining the temperature value at each sampling time within the current monitoring period with the corresponding chelation rate change rate value. The ratio of the product of the covariance of the two sequences and their respective standard deviations is calculated, and the obtained ratio is used as the temperature-chelation rate coupling coefficient.

6. The production process control method for humic acid chelated zinc compound fertilizer granules as described in claim 1, characterized in that, Step S21 is as follows: The coupling coefficient of the current monitoring period is compared with the zero value. If the coefficient is less than zero, it is determined to be a negative correlation. The heating system is controlled to reduce the temperature of the chelation reaction system by one temperature step value, and the stirring system speed is controlled to reduce by one speed percentage. This operation is repeated until the coupling coefficient is greater than or equal to zero. After the coupling coefficient is regressed to a positive correlation, the rate of change of chelation rate in the current monitoring period is compared with the rate of change of chelation rate in the previous monitoring period. If the current value is less than the value in the previous period, it is determined to be decreasing, and the stirring system is controlled to increase the stirring speed by one speed percentage. If, after increasing the stirring speed, the rate of change of chelation rate in three consecutive monitoring cycles shows a decreasing trend in each cycle, or the rate of change of chelation rate is less than the preset rate convergence value, then the stirring system is controlled to operate in a pulse mode of running forward for a first duration, stopping for a second duration, running in reverse for a first duration, and stopping for a second duration, and the heating system is controlled to increase the temperature of the reaction system step by step according to the temperature level sequence, with each temperature level maintained for a third duration.

7. The production process control method for humic acid chelated zinc compound fertilizer granules as described in claim 6, characterized in that, The method for obtaining the temperature level sequence is as follows: Based on the initial temperature value and the preset temperature rise offset, a temperature level sequence containing multiple temperature level values ​​is generated sequentially according to an arithmetic progression.

8. The production process control method for humic acid chelated zinc compound fertilizer granules as described in claim 6, characterized in that, During the execution of the pulse stirring and stepped heating synergistic activation mode, the following is also included: The rate of change of chelation rate is continuously monitored. If the rate of change of chelation rate increases for two consecutive monitoring cycles, the activation mode is exited and the process returns to execution S21.

9. The production process control method for humic acid chelated zinc compound fertilizer granules as described in claim 1, characterized in that, Step S22 is as follows: Calculate the ratio of the rate of change of chelation rate to the rate of acceleration of inoculation during the current monitoring period, and use this ratio as the chelation efficiency index per unit rate of acceleration of inoculation. The deviation between the chelation efficiency index and the preset target efficiency is calculated and used as the efficiency deviation for the current monitoring period. If the current period is the initial monitoring cycle, the efficiency deviation will be used as the cumulative deviation value. Otherwise, add the efficiency deviation to the cumulative deviation value of the previous monitoring period and update the current cumulative deviation value; Multiply the efficiency deviation of the current monitoring period by a preset proportional coefficient to obtain the proportional term, multiply the cumulative deviation value of the current monitoring period by a preset integral coefficient to obtain the integral term, and add the proportional term and the integral term to obtain the rate correction amount. The rate correction is added to the acceleration rate of the current monitoring cycle to obtain the acceleration rate of the next monitoring cycle, and the acceleration rate of the next monitoring cycle is written into the control system register.

10. The production process control method for humic acid chelated zinc compound fertilizer granules as described in claim 6, characterized in that, The S3 steps are as follows: Real-time monitoring of the chelation rate change rate and coupling coefficient in each monitoring cycle; When the absolute value of the chelation rate change rate for three consecutive monitoring cycles is less than the preset rate convergence value, and the coupling coefficient for each corresponding cycle is greater than zero, and the absolute value of the difference between the cumulative zinc source addition and the total zinc source is less than the preset allowable error value, the reaction termination condition is determined to be met. Turn off the heating and stirring systems, open the discharge valve, and transport the chelated product in the reactor to the granulation process.

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