An intelligent control system for an automated reaction vessel for the precipitation of ammonium tetramolybdate.

Abstract

This invention relates to the field of intelligent control technology for reaction vessels, and discloses an automated intelligent control system for an ammonium tetramolybdate (AM) precipitating acid reaction vessel. The system includes: a constraint modeling and monitoring module for collecting monitoring data and establishing constraints; a zoned logic control module for dividing the process into sections and setting pH targets; a pH master control module for controlling the acid addition rate and applying valve position limits; a particle interlock control module for triggering the secondary loop and linking it to the main loop; a refluxing quantitative execution module for determining the alkali supply volume and feeding time; a continuous reflux adjustment module for refluxing the slurry according to the reflux ratio; and a material balance correction module for calculating the precipitation rate and achieving closed-loop correction. This invention achieves fully automated monitoring, segmented control, and closed-loop correction during the operation of the AM precipitating acid reaction vessel, realizing stable, efficient, and precise control of the reaction process.

Description

Technical Field

[0001] This invention belongs to the field of intelligent control technology for reaction vessels, specifically relating to an intelligent control system for an automated reaction vessel for the precipitation of ammonium tetramolybdate. Background Technology

[0002] Ammonium tetramolybdate is an important intermediate in molybdenum-based chemical products, widely used in catalysts, metallurgy, electronics, and chemical synthesis. Its preparation typically employs acid precipitation, where a molybdenum-containing solution reacts with an acidic medium to form ammonium tetramolybdate precipitate. However, this process is characterized by strong nonlinearity, multivariate coupling, and hysteresis. The reaction vessel is susceptible to fluctuations in pH, temperature gradients, and changes in particle growth rate during operation, leading to decreased system stability, uneven product particle size distribution, and reduced molybdenum recovery from the mother liquor. Traditional manual control methods struggle to achieve precise control over complex reaction systems, especially when acid precipitation and crystallization occur simultaneously. This often results in over-acidification, crystal refinement, and decreased filtration performance, causing product quality fluctuations and increased energy consumption.

[0003] Most existing automated systems only control single variables, lacking comprehensive coordination of chemical equilibrium, mass transfer kinetics, and particle evolution, thus failing to achieve global optimization of the reaction process. Furthermore, material balance monitoring still relies on manual sampling and offline analysis, resulting in significant feedback lag and making it difficult to meet the stability requirements of continuous production. Summary of the Invention

[0004] This invention provides an intelligent control system for an automated reaction vessel for the acid precipitation of ammonium tetramolybdate, which solves the technical problems of low control precision, delayed process response, uneven particle distribution, and inability to provide real-time feedback on material balance in the acid precipitation process in related technologies.

[0005] This invention provides an intelligent control system for an automated reaction vessel for the precipitation of ammonium tetramolybdate, comprising:

[0006] The constraint modeling and monitoring module is used to collect monitoring data during the operation of the reactor and establish constraint conditions.

[0007] The partition logic control module is used to divide the acid precipitation process into a pretreatment section, a transition section, a core crystallization section, and a correction section, and to set the pH target and inter-section migration conditions.

[0008] The pH control module is used to perform aggregate tracking control of the pH main circuit, adjust the slope of valve position change according to the monitored value to control the acid addition rate, and apply valve position limit;

[0009] The particle interlock control module is used to perform gating, limiting and sequential interlocking of the particle sub-circuit. It triggers fixed sequence actions based on the particle statistics and fine crystal ratio in the monitoring data and links with the pH main circuit.

[0010] The re-dissolution quantitative execution module is used to determine the required alkali solution dispensing volume and feeding time for the re-dissolution action based on the effective volume of the reactor, the current pH, the target pH for re-dissolution, and the equivalent concentration of the alkali solution.

[0011] The continuous reflux adjustment module is used to perform continuous reflux. It determines the reflux ratio based on the fine crystal ratio at fixed time intervals and refluxes the slurry from the correction section to the transition section according to the reflux ratio, with the remainder entering the separation and washing process.

[0012] The material balance and correction module is used to calculate the sedimentation rate at fixed time intervals based on the feed flow rate and its corresponding molybdenum concentration, the discharge flow rate and its corresponding molybdenum concentration in the mother liquor, and the effective volume of the reactor.

[0013] Furthermore, the constraints include chemical constraints and particle constraints. The chemical constraints limit the pH and temperature, while the particle constraints limit the median particle size, the proportion of fine crystals, and the specific resistance of the filter cake.

[0014] The monitored parameters include pH, temperature, slurry solids content, feed flow rate, discharge flow rate, molybdenum concentration in mother liquor, and particle statistics. The particle statistics include median particle size, fine crystal ratio, and filter cake specific resistance.

[0015] Furthermore, within each process segment, when the pH reaches the target pH for that segment and the temperature and particle statistics meet the constraints, an inter-segment migration determination is triggered, and the process segment switching is automatically executed based on the inter-segment determination result.

[0016] The inter-segment migration determination is used to perform a weighted summation of the current pH deviation and temperature deviation to form a weighted absolute sum, which is then compared with a preset error threshold. When the weighted absolute sum is less than the preset error threshold, a migration confirmation signal is output, and the process segment switching is automatically executed. The pH deviation and temperature deviation refer to the differences between the current detection value and the pH target and temperature target corresponding to the process segment, respectively.

[0017] Furthermore, the ensemble tracking control of the pH master loop is performed, including:

[0018] Step 11: When the pH is higher than the pH target, it is defined as a positive deviation; when the pH is lower than the pH target, it is defined as a negative deviation; when the pH is equal to the pH target, the pH deviation is zero.

[0019] Step 12: Multiply the pH deviation by the fixed gain constant to obtain the valve position change rate. When the pH deviation is positive, increase the valve position opening; when the pH deviation is negative, decrease the valve position opening; when the pH deviation is zero, keep the valve position unchanged.

[0020] Step 13: Within a fixed sampling period, calculate the product of the valve position change rate and the sampling period time, and add it to the valve position opening of the previous sampling period to obtain the updated valve position opening.

[0021] Furthermore, the acid addition rate is controlled by adjusting the slope of the valve position change based on the monitored values, and a valve position limit is applied, including:

[0022] Step 21: Use the product of temperature deviation and temperature compensation coefficient as a correction coefficient to linearly correct the valve position change rate.

[0023] Step 22: When the temperature deviation is positive, decrease the valve position change rate and reduce the acid addition rate; when the temperature deviation is negative, increase the valve position change rate and increase the acid addition rate; when the temperature deviation is zero, keep the valve position change rate and acid addition rate constant. The acid addition rate is proportional to the valve position change rate.

[0024] Step 23: Apply limiting constraints to the valve position opening degree and the valve position change rate respectively, limit the valve position opening degree to between the preset minimum opening degree and the preset maximum opening degree, and limit the absolute value of the valve position change rate to not exceed the maximum allowable change rate. When the valve position opening degree or the valve position change rate touches the limit value, soft limiting control is automatically activated. The soft limiting control means gradually reducing the valve position change rate by proportional decrease.

[0025] Furthermore, the particle interlock control module includes:

[0026] Step 31: Obtain the median particle size, fine crystal ratio, and filter cake specific resistance. Calculate the deviation based on the absolute difference from their respective target values, and sum them by weight to obtain the particle deviation. When the particle deviation exceeds the preset particle deviation threshold, trigger the particle sub-loop control logic.

[0027] Step 32: Activate the gating and limiting control logic. In the triggered state, lock the valve position command and acid addition speed of the pH main circuit, and apply limiting constraints to the valve position change rate and stirring speed respectively. When the fine crystal ratio is continuously higher than the target ratio within the first preset time, freeze the valve position signal and perform the re-dissolution action.

[0028] Step 33: Activate the sequential interlock logic and execute the following fixed sequence of actions: freezing the acid valve, raising the pH, maintaining constant temperature, reducing the pH to the target level in segments, and increasing the stirring speed. Specifically, after adjusting the pH to the target pH level at a fixed rate of increase and maintaining it for a second preset time, the pH level is reduced to the target pH level of the core crystallization segment according to the preset segmented reduction curve. At the same time, the stirring speed is increased to a fixed multiple of the base speed. After completing the interlock action, the gate control is released and the main loop collection tracking control is restored.

[0029] Furthermore, the required alkali solution volume and feeding time for the re-dissolution process are determined, including:

[0030] Step 41: Obtain the effective volume of the reactor, the current pH, the target pH for reconstitution, and the equivalent concentration of the alkaline solution. Calculate the pH difference based on the difference between the current pH and the target pH for reconstitution. Divide the product of the effective volume of the reactor and the pH difference for reconstitution by the equivalent concentration of the alkaline solution and multiply by the buffer compensation coefficient to determine the alkaline solution dispensing volume. When the pH difference for reconstitution is greater than zero, perform reconstitution dispensing.

[0031] Step 42: Calculate the basic feeding time based on the ratio of the maximum flow rate of the feeding pipeline to the alkali solution feeding volume, and correct the basic feeding time with a smoothing coefficient to obtain the corrected feeding time. Then, perform the alkali solution feeding operation according to the segmented rate curves of slow start, constant speed, and slow stop respectively.

[0032] Step 43: When the current pH reaches the target pH for reconstitution and the pH change rate is lower than the set change rate threshold, maintain constant temperature and constant speed stirring, keep the feeding terminated state for the third preset time, close the alkali valve after the end of the holding period and output a reconstitution completion signal.

[0033] Further, the reflux ratio is determined, and the slurry from the correction section is refluxed to the transition section according to the reflux ratio, with the remainder entering the separation and washing process, including:

[0034] Step 51: Calculate the difference between the fine grain ratio and the target fine grain ratio to obtain the fine grain ratio deviation. Then, correct the basic reflux ratio by multiplying the basic reflux ratio by the fine grain ratio deviation to determine the reflux ratio. When the fine grain ratio is higher than the target fine grain ratio, increase the reflux ratio; when the fine grain ratio is lower than the target fine grain ratio, decrease the reflux ratio.

[0035] Step 52: Determine the reflux flow rate based on the product of the reflux ratio and the total discharge flow rate, and reflux the corrective section slurry to the transition section according to the reflux flow rate, while the remaining part is separated and washed;

[0036] Step 53: During the reflux process, monitor the liquid level difference between the reflux section and the transition section. When the liquid level difference exceeds the preset liquid level threshold, automatically adjust the reflux pump speed.

[0037] Furthermore, when the refluxing quantitative execution module and the continuous reflux adjustment module work simultaneously, the sum of the current alkali supply volume and the reflux flow rate is calculated and compared with the effective volume of the reactor. If the ratio of the former to the latter exceeds the first preset ratio, the subsequent reflux start time is automatically delayed.

[0038] Furthermore, the process of calculating the precipitation rate includes:

[0039] Step 61: Subtract the product of the feed flow rate and its corresponding molybdenum concentration from the product of the discharge flow rate and its corresponding molybdenum concentration in the mother liquor, and then divide by the effective volume of the reactor to obtain the precipitation rate for the current cycle; the precipitation rate reflects the instantaneous material balance state of molybdenum in the system.

[0040] Step 62: Calculate the absolute difference between the sedimentation rate of the current cycle and the sedimentation rate of the previous cycle, compare the absolute difference with the preset rate threshold, and generate a stability determination result.

[0041] Step 63: When the absolute difference is greater than the preset rate threshold, it is determined to be unstable. The acid addition rate of the pH main circuit is automatically adjusted according to the precipitation rate of the current cycle and the precipitation rate of the previous cycle. If the precipitation rate of the current cycle is large, the acid addition rate is reduced; otherwise, the acid addition rate is increased. When the stability determination result is stable, the acid addition rate is kept unchanged.

[0042] The beneficial effects of this invention are as follows: By establishing a multi-level automated control system, this invention achieves intelligent management of the entire process of the ammonium tetramolybdate precipitation reactor, from pH adjustment and particle distribution control to material balance correction. The system couples the pH main loop with the particle secondary loop to achieve synchronous control of chemical balance and particle evolution; through the synergistic effect of the re-dissolution quantitative execution module and the continuous reflux adjustment module, it maintains a dynamic balance between the fine crystal ratio and liquid level, preventing over-precipitation and crystal refinement; the re-dissolution and reflux linkage coordination mechanism effectively avoids system liquid level overload; and online material balance calculation and closed-loop correction achieve adaptive correction of the precipitation rate. Overall, this invention can achieve real-time monitoring, dynamic judgment, and precise control of reactor operation under unattended conditions, thereby improving product purity and particle size uniformity, stabilizing the molybdenum recovery rate of the mother liquor, and enhancing the safety and automation level of the production process. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of a module of an intelligent control system for an automated reaction vessel for the precipitation of ammonium tetramolybdate, according to the present invention. Detailed Implementation

[0044] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0045] It should be noted that, unless otherwise defined, the technical or scientific terms used in one or more embodiments of the present invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in one or more embodiments of the present invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0046] like Figure 1 As shown, an intelligent control system for an automated reaction vessel for the precipitation of ammonium tetramolybdate includes:

[0047] Constraint modeling and monitoring module 1 is used to collect monitoring quantities during the operation of the reactor and establish constraint conditions;

[0048] The partition logic control module 2 is used to divide the acid precipitation process into a pretreatment section, a transition section, a core crystallization section and a correction section, and to set the pH target and inter-section migration conditions.

[0049] The pH control module 3 is used to perform aggregate tracking control of the pH main circuit, adjust the slope of valve position change according to the monitored value to control the acid addition rate, and apply valve position limit;

[0050] The particle interlock control module 4 is used to perform gating, limiting and sequential interlocking of the particle sub-circuit. It triggers fixed sequence actions and links with the pH main circuit based on the particle statistics and fine crystal ratio in the monitoring data.

[0051] The re-dissolution quantitative execution module 5 is used to determine the required alkaline solution supply volume and feeding time for the re-dissolution action based on the effective volume of the reactor, the current pH, the target pH for re-dissolution, and the equivalent concentration of the alkaline solution.

[0052] The continuous reflux adjustment module 6 is used to perform continuous reflux. It determines the reflux ratio according to the fine crystal ratio at fixed time intervals and refluxes the slurry in the correction section to the transition section according to the reflux ratio, and the remainder enters the separation and washing process.

[0053] The material balance and correction module 7 is used to calculate the sedimentation rate at fixed time intervals based on the feed flow rate and its corresponding molybdenum concentration, the discharge flow rate and its corresponding molybdenum concentration in the mother liquor, and the effective volume of the reactor.

[0054] In one embodiment of the present invention, the constraints include chemical constraints and particle constraints. The chemical constraints limit the pH and temperature to avoid the formation of byproducts or solute supersaturation in the system. The particle constraints limit the median particle size, fine crystal ratio, and filter cake specific resistance to ensure the stability of the product's filtration performance and purity. pH, as a reflection of the hydrogen ion concentration in the reaction system, is a core variable controlling the ammonium salt precipitation rate and particle size distribution. The temperature parameter directly affects the balance between the reaction rate constant and the crystallization rate. The median particle size refers to the particle size corresponding to a cumulative volume distribution of 50% in the particle population, used to characterize the average size of the precipitated particles. The fine crystal ratio is the volume fraction of particles smaller than a preset threshold in the particle population, reflecting the proportion of small particles in the system. The filter cake specific resistance is a fluid resistance index generated per unit volume of filter cake during the filtration process, used to evaluate solid-liquid separation performance.

[0055] The monitored parameters include pH, temperature, slurry solids content, feed flow rate, discharge flow rate, molybdenum concentration in mother liquor, and particle statistics. Particle statistics include median particle size, fine crystal ratio, and filter cake specific resistance. Slurry solids content refers to the volume fraction of solid particles in the total slurry volume, used to represent the solid-liquid phase ratio. The molybdenum concentration in mother liquor represents the residual level of molybdenum ions in the dissolved phase, used to determine the degree of reaction conversion and molybdenum recovery rate. Particle statistics are obtained using an online particle size analyzer or an optical scattering detection device. All collected monitoring parameters are digitally encoded and synchronized with time.

[0056] In one embodiment of the present invention, the operating cycle of the ammonium tetramolybdate acid precipitation reactor is divided into multiple process segments. Each process segment has independent acidity and alkalinity targets and temperature targets. Within each process segment, when the acidity reaches the acidity target of the process segment and the temperature and particle statistics meet the constraints, the inter-segment migration judgment is triggered, and the process segment switching is automatically executed according to the inter-segment judgment result.

[0057] The inter-segment migration determination is used to perform a weighted summation of the current pH deviation and temperature deviation to form a weighted absolute sum, which is then compared with a preset error threshold. When the weighted absolute sum is less than the preset error threshold, a migration confirmation signal is output, and the process segment switching is automatically executed. The pH deviation and temperature deviation refer to the differences between the current detection value and the pH target and temperature target corresponding to the process segment, respectively, which are used to reflect the degree of deviation from chemical equilibrium and to assess the stability of thermodynamic conditions.

[0058] This embodiment uses dual-constraint criteria of pH and temperature targets to make the switching logic of the process segment adaptive, automatically determining whether to enter the next stage based on the actual reaction state of the system, reducing human decision-making errors. By introducing a weighted absolute sum criterion, the system can simultaneously consider the deviation of chemical equilibrium and thermal equilibrium, achieving coordinated stability judgment of multiple variables, thereby improving the accuracy and repeatability of reaction segment switching, and ensuring that the acid precipitation of ammonium tetramolybdate reaction process remains continuous, stable and efficient.

[0059] In one embodiment of the present invention, performing aggregate tracking control of the pH master loop includes:

[0060] Step 11: When the pH is higher than the pH target, it is defined as a positive deviation, indicating that the system is less acidic. When the pH is lower than the pH target, it is defined as a negative deviation, indicating that the system is more acidic. When the pH is equal to the pH target, the pH deviation is zero.

[0061] Step 12: Multiply the pH deviation and the fixed gain constant to obtain the valve position change rate. When the pH deviation is positive, increase the valve opening to increase the acid addition rate; when the pH deviation is negative, decrease the valve opening to decrease the acid addition rate; when the pH deviation is zero, keep the valve position unchanged. The fixed gain constant is set to different values ​​according to the process section type. A smaller value is used in the core crystallization section to avoid over-adjustment, and a larger value is used in the pretreatment and transition sections to speed up the response. When the valve position change rate exceeds the preset upper or lower limit, the system automatically applies a limiting protection to prevent acid addition overshoot or valve mechanical overtravel.

[0062] Step 13: Within a fixed sampling period, the updated valve opening is obtained by calculating the product of the valve position change rate and the sampling period time, and adding it to the valve opening of the previous sampling period. The fixed sampling period is preset according to the effective volume of the reactor and the acid addition response time, so that the update frequency of the valve opening matches the chemical response time of the reaction system.

[0063] This embodiment achieves adaptive bidirectional adjustment through deviation sign determination and gain weighting, making the response to changes in pH directional and proportional, thus improving the system's adjustment sensitivity and stability. By setting differentiated gain constants in different process stages, dynamic matching between the adjustment rate and the chemical reaction rate is achieved, enabling rapid entry into the reaction zone in the initial stage and preventing excessive fluctuations in the crystallization stage, thereby realizing real-time and precise adjustment of pH changes in the acid precipitation ammonium tetramolybdate reaction system.

[0064] In one embodiment of the present invention, the acid addition rate is controlled by adjusting the slope of the valve position change based on the monitored quantity, and a valve position limit is applied, including:

[0065] Step 21: Use the product of temperature deviation and temperature compensation coefficient as a correction coefficient to linearly correct the valve position change rate.

[0066] Step 22: When the temperature deviation is positive, i.e., the system temperature is higher than the temperature target, reduce the valve position change rate and decrease the acid addition rate to prevent the exothermic acidification reaction from causing a further increase in temperature. When the temperature deviation is negative, increase the valve position change rate and increase the acid addition rate to enhance the exothermic reaction intensity of the system and promote temperature recovery. When the temperature deviation is zero, keep the valve position change rate and acid addition rate constant to maintain the thermal stability of the system. The acid addition rate is proportional to the valve position change rate.

[0067] Step 23: Apply limiting constraints to the valve opening degree and valve position change rate to prevent the valve opening degree or valve position change rate from exceeding the allowable range of the equipment or causing control oscillations. Limit the valve opening degree between the preset minimum opening degree and the preset maximum opening degree to avoid sudden changes in acid flow caused by the valve being completely closed or fully open. Limit the absolute value of the valve position change rate to not exceed the maximum allowable change rate, thereby limiting the valve action speed. When the valve opening degree or valve position change rate reaches the limit value, soft limiting control is automatically activated. The soft limiting control means gradually reducing the valve position change rate by proportional decrease, so that the valve action gradually slows down rather than stops instantaneously, thereby effectively preventing liquid flow shock and acid flow fluctuation caused by sudden changes in valve action.

[0068] This embodiment establishes a linear coupling relationship between acid addition rate and temperature state by weighting temperature deviation correction and temperature compensation coefficient, realizing coordinated control of chemical reaction rate and thermodynamic balance. Through dynamic limiting and soft limiting dual-layer constraints, it avoids flow shock caused by excessive valve action or sudden changes in acid addition rate, improves the operational stability and equipment safety of the reaction system, enhances the fine control capability of acid precipitation of ammonium tetramolybdate reaction, and improves the safety of reactor operation.

[0069] In one embodiment of the present invention, the particle interlock control module includes:

[0070] Step 31: Obtain the median particle size, fine crystal ratio, and filter cake specific resistance. Calculate the deviation degree based on the absolute difference from each target value, and sum them using weighted averages to obtain the particle deviation degree. When the particle deviation degree exceeds a preset particle deviation threshold, trigger the particle sub-loop control logic. In the particle deviation degree calculation, the weighting coefficients of the weighted summation process are set according to the degree of influence of different indicators on product quality. Preferably, a higher weight is assigned to the fine crystal ratio, and a secondary weight to the filter cake specific resistance, to highlight the priority of crystallization particle size control. The particle sub-loop control logic is used for anomaly identification and response scheduling of particle distribution status, responsible for initiating gating and limiting control logic as well as sequential interlocking logic, realizing a complete closed-loop process from decoupling of the main loop to recovery.

[0071] Step 32: Activate the gating and limiting control logic. In the triggered state, lock the valve position command and acid addition rate of the pH main circuit, and apply limiting constraints to the valve position change rate and stirring speed respectively. When the fine crystal ratio is continuously higher than the target ratio within the first preset time, the system determines that the system has an excessive fineness trend, automatically freezes the valve position signal and performs a re-dissolution action to restore the crystal distribution balance.

[0072] Step 33: After triggering the remelting action, the sequential interlock logic is activated, executing the following fixed sequence of actions: freezing the acid valve, raising the pH, maintaining constant temperature, gradually lowering the pH to the target level, and increasing the stirring speed. Specifically, the pH is adjusted to the remelting target level at a fixed rate and maintained for a second preset time. Then, it decreases to the target pH of the core crystallization stage according to a preset segmented descent curve. Simultaneously, the stirring speed is increased to a fixed multiple of the base speed to enhance the system's fluid shear and mass transfer efficiency, promoting uniform crystal growth. After completing the interlock action, the gate is released, and the main loop's aggregate tracking control is restored, allowing the reaction system to re-enter steady-state operation. The entire secondary loop process is decoupled from the main loop at the logical level but coordinates with the main loop at the execution level, ensuring that the system maintains global stability even under local disturbances.

[0073] This embodiment achieves comprehensive monitoring of multiple parameters such as median particle size, fine crystal ratio, and filter cake specific resistance through particle deviation calculation, enabling the system to quantitatively identify the degree and direction of abnormal particle distribution. Through a dual mechanism of gating and limiting, it prevents chain deviations caused by continued adjustment of the main loop under abnormal particle conditions, ensuring system stability. Through sequential interlocking logic, it enables remelting and crystallization to proceed in a coordinated manner under unified scheduling, thereby maintaining the uniformity of the particle group structure, ensuring the stability of product particle size distribution and filtration performance, and enhancing the system's intelligent response capability.

[0074] In one embodiment of the present invention, determining the required alkali solution volume and feeding time for the re-dissolution action includes:

[0075] Step 41: Obtain the effective volume of the reactor, the current pH, the target pH for reconstitution, and the equivalent concentration of the alkali solution. Calculate the reconstitution pH difference based on the difference between the current pH and the target pH for reconstitution. Determine the alkali supply volume by multiplying the effective volume of the reactor by the reconstitution pH difference, dividing by the equivalent concentration of the alkali solution, and multiplying by the buffer compensation coefficient. When the reconstitution pH difference is greater than zero, the system determines that the system is too acidic and performs reconstitution supply. The target pH for reconstitution is a preset target value, representing the pH equilibrium point the system should reach after reconstitution. The buffer compensation coefficient is used to compensate for nonlinear responses caused by acid-base buffering effects, ion adsorption, or reaction hysteresis in the system, and its value ranges from 0.9 to 1.3.

[0076] Step 42: The basic feeding time is determined based on the ratio of the maximum flow rate of the feeding pipeline to the alkali solution supply volume. This basic feeding time is then corrected using a smoothing coefficient to obtain the corrected feeding time. The alkali solution feeding operation is then performed according to segmented rate curves of slow start, constant speed, and slow stop. Specifically, the flow rate is slowly increased at the beginning of feeding, a constant speed is maintained in the middle stage, and the flow rate is gradually reduced and stopped at the end, thus avoiding liquid flow impact and excessive concentration gradients. The maximum flow rate of the feeding pipeline is measured in real-time by a flow meter, reflecting the upper limit of the alkali solution delivery capacity. The smoothing coefficient correction is used to prevent feeding rate instability caused by sudden changes in instantaneous flow rate.

[0077] Step 43: When the current pH reaches the target pH for reconstitution and the pH change rate is lower than the set change rate threshold, the system determines that the reconstitution process is stabilizing, maintains constant temperature and constant speed stirring, and keeps the feeding terminated state for a third preset time. After the end of the holding period, the alkali valve is closed and a reconstitution completion signal is output. This reconstitution completion signal serves as a trigger flag for subsequent control logic and is used to reactivate the pH main loop set tracking control and crystallization section operation.

[0078] This embodiment achieves quantitative control of the alkali supply by accurately calculating the pH difference and the effective volume of the reactor, ensuring accurate matching of stoichiometric relationships during the reconstitution process. By setting a smooth feeding curve, it avoids pH overshoot caused by sudden flow changes, ensuring continuous and controllable changes in system acidity, preventing secondary crystal refinement or agglomeration, and realizing automated reconstitution and self-repair of particle distribution in the ammonium tetramolybdate acid precipitation reactor, thereby improving the system's intelligent adjustment level and product quality stability.

[0079] In one embodiment of the present invention, a reflux ratio is determined, and the slurry from the correction section is refluxed to the transition section according to the reflux ratio, with the remainder entering the separation and washing process, including:

[0080] Step 51: Calculate the difference between the fine crystal ratio and the target fine crystal ratio to obtain the fine crystal ratio deviation. Correct the base reflux ratio by multiplying the base reflux ratio by the fine crystal ratio deviation to determine the reflux ratio. When the fine crystal ratio is higher than the target fine crystal ratio, it indicates that the content of fine crystals in the system is too high, and the reflux ratio needs to be increased. When the fine crystal ratio is lower than the target fine crystal ratio, the particles in the system are too large, and the reflux ratio needs to be decreased to speed up the material turnover. The target fine crystal ratio is an empirically set value, representing the ideal particle distribution state when the system is running stably. The base reflux ratio is a reference value determined during the process debugging stage based on the equipment volume, reaction rate, and slurry concentration.

[0081] Step 52: Determine the reflux flow rate based on the product of the reflux ratio and the total discharge flow rate. Reflux the corrective section slurry to the transition section according to the reflux flow rate, and perform separation and washing on the remaining portion. The total discharge flow rate is measured in real time by a flow meter and represents the overall output rate of the corrective section slurry. Through this distribution method, the system can maintain a closed-loop material circulation under uninterrupted operation conditions, allowing fine crystals to continue growing in the transition section while mature particles are discharged in a timely manner, thereby achieving a dynamic balance between sedimentation and separation processes.

[0082] Step 53: During the reflux process, monitor the liquid level difference between the reflux section and the transition section. The liquid level difference is used to reflect the slurry flow resistance and the system material balance. When the liquid level difference exceeds the preset liquid level threshold, automatically adjust the reflux pump speed to reduce the flow rate and restore the liquid level balance. When the liquid level difference is less than the threshold, maintain the existing pump speed to ensure smooth system circulation.

[0083] This embodiment achieves stable regulation of the acid precipitation ammonium tetramolybdate reaction system by correcting the fine crystal ratio deviation, distributing the reflux flow rate, and controlling the liquid level difference balance, thus ensuring the coordination and unity among particle distribution, fluid dynamics, and material balance.

[0084] In one embodiment of the present invention, when the system detects that the rehydration quantitative execution module and the continuous reflux adjustment module are operating simultaneously, a coordinated processing of rehydration and reflux is performed. The system first reads the current alkali supply volume and reflux flow rate, then superimposes these to obtain the instantaneous total input volume of the system. This is compared with the effective volume of the reactor. When the ratio of the instantaneous total input volume to the effective volume of the reactor exceeds a first preset ratio, the system determines that the liquid phase volume fraction of the current system is too high, posing a risk of exceeding the liquid level limit. The system automatically executes reflux start-up delay control. Specifically, the system generates a reflux delay signal, postponing the subsequent reflux start-up time by a fixed delay coefficient, allowing the alkali rehydration reaction to complete first, and then resuming the reflux operation only after the liquid level drops to a safe range. The delay coefficient is dynamically adjusted based on the system discharge rate, the effective volume of the reactor, and the rehydration replenishment volume to ensure that the liquid level remains within the safe operating range throughout the entire cycle.

[0085] This embodiment, through the above-mentioned coordinated control process of remelting and reflux, can dynamically balance the liquid volume in a multi-module parallel operation scenario, preventing the risk of liquid level rise, stirring instability or overflow caused by the superposition of addition and reflux, thereby ensuring the continuity of the process and equipment safety, and improving the safety, stability and automation level of the system in a parallel control scenario.

[0086] In one embodiment of the present invention, the sedimentation rate is calculated at fixed time intervals based on the feed flow rate and its corresponding molybdenum concentration, the discharge flow rate and its corresponding molybdenum concentration in the mother liquor, and the effective volume of the reactor, including:

[0087] Step 61: Subtract the product of the feed flow rate and its corresponding molybdenum concentration from the product of the discharge flow rate and its corresponding molybdenum concentration in the mother liquor, and then divide by the effective volume of the reactor to obtain the precipitation rate for the current cycle; the precipitation rate reflects the instantaneous material balance state of molybdenum in the system.

[0088] Step 62: Calculate the absolute difference between the sedimentation rate of the current cycle and the sedimentation rate of the previous cycle, compare the absolute difference with the preset rate threshold, and generate a stability determination result.

[0089] Step 63: When the absolute difference is greater than the preset rate threshold, it is determined to be unstable. The acid addition rate of the main acid-base circuit is automatically adjusted according to the precipitation rate of the current cycle and the precipitation rate of the previous cycle. If the precipitation rate of the current cycle is large, it means that the precipitation rate of the system is too fast and the acid addition rate needs to be reduced to slow down the acidification rate. Otherwise, it means that the acidification is insufficient or the system reaction is lagging, and the acid addition rate needs to be increased. When the stability determination result is stable, the acid addition rate is kept unchanged.

[0090] To prevent oscillations during the adjustment process, the system employs linear amplitude limiting constraints when performing speed corrections, restricting the adjustment range of the acid addition rate in each sampling cycle to ensure smoothness and control stability. Furthermore, to avoid transient misjudgments, the system performs trend analysis over multiple consecutive sampling cycles, initiating correction only when the rate deviation consistently exceeds a threshold, thus achieving tolerance for transient fluctuations and timely response to persistent anomalies.

[0091] In this embodiment, through the above-described online material balance and closed-loop correction process, the system can monitor the changes in the precipitation rate of molybdenum in the reaction system in real time without relying on manual intervention, forming a dynamic feedback control mechanism based on material balance, thereby improving the system's automation level and process control accuracy.

[0092] It should be noted that the interval and threshold sizes are set for ease of comparison. The size of the threshold depends on the amount of sample data and the base number set by those skilled in the art for each set of sample data, as long as it does not affect the proportional relationship between the parameter and the quantized value. Furthermore, the above formulas are all dimensionless calculations, and the formulas are derived from software simulations using a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0093] The embodiments of the present invention have been described above, but the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms based on the guidance of the present embodiments, all of which are within the protection scope of the present embodiments.

Claims

1. An intelligent control system for an automated reaction vessel for the acid precipitation of ammonium tetramolybdate, characterized in that, include: The constraint modeling and monitoring module is used to collect monitoring data during the operation of the reactor and establish constraint conditions. The partition logic control module is used to divide the acid precipitation process into a pretreatment section, a transition section, a core crystallization section, and a correction section, and to set the pH target and inter-section migration conditions. The pH control module is used to perform aggregate tracking control of the pH main circuit, adjust the slope of valve position change according to the monitored value to control the acid addition rate, and apply valve position limit; The particle interlock control module is used to perform gating, limiting, and sequential interlocking of the particle sub-loop. It triggers fixed-sequence actions based on particle statistics and fine crystal ratio from the monitored data and is linked to the pH main loop, including: Step 31: Obtain the median particle size, fine crystal ratio, and filter cake specific resistance. Calculate the deviation based on the absolute difference from their respective target values, and sum them by weight to obtain the particle deviation. When the particle deviation exceeds the preset particle deviation threshold, trigger the particle sub-loop control logic. Step 32: Activate the gating and limiting control logic. In the triggered state, lock the valve position command and acid addition speed of the pH main circuit, and apply limiting constraints to the valve position change rate and stirring speed respectively. When the fine crystal ratio is continuously higher than the target ratio within the first preset time, freeze the valve position signal and perform the re-dissolution action. Step 33: Activate the sequential interlock logic and execute the following fixed sequence of actions: freeze the acid valve, raise the pH, maintain constant temperature, reduce the pH to the target level in segments, and increase the stirring speed. The pH is adjusted to the target pH level at a fixed rate of increase and maintained for a second preset time. Then, it is reduced to the target pH level of the core crystallization segment according to the preset segmented reduction curve. At the same time, the stirring speed is increased to a fixed multiple of the base speed. After the interlock action is completed, the gate control is released and the main loop collection tracking control is restored. The re-dissolution quantitative execution module is used to determine the required alkali solution dispensing volume and feeding time for the re-dissolution action based on the effective volume of the reactor, the current pH, the target pH for re-dissolution, and the equivalent concentration of the alkali solution. The continuous reflux adjustment module is used to perform continuous reflux. It determines the reflux ratio based on the fine crystal ratio at fixed time intervals and refluxes the slurry from the correction section to the transition section according to the reflux ratio, with the remainder entering the separation and washing process. The material balance and correction module is used to calculate the sedimentation rate at fixed time intervals based on the feed flow rate and its corresponding molybdenum concentration, the discharge flow rate and its corresponding molybdenum concentration in the mother liquor, and the effective volume of the reactor.

2. The intelligent control system for an automated reaction vessel for precipitating ammonium tetramolybdate according to claim 1, characterized in that, The constraints include chemical constraints and particle constraints. The chemical constraints limit the acidity, alkalinity and temperature, while the particle constraints limit the median particle size, the proportion of fine crystals and the specific resistance of the filter cake. The monitored parameters include pH, temperature, slurry solids content, feed flow rate, discharge flow rate, molybdenum concentration in mother liquor, and particle statistics. The particle statistics include median particle size, fine crystal ratio, and filter cake specific resistance.

3. The intelligent control system for an automated reaction vessel for precipitating ammonium tetramolybdate according to claim 1, characterized in that, Within each process segment, when the pH reaches the target pH for that segment and the temperature and particle statistics meet the constraints, an inter-segment migration determination is triggered, and the process segment switching is automatically executed based on the inter-segment determination result. The inter-segment migration determination is used to perform a weighted summation of the current pH deviation and temperature deviation to form a weighted absolute sum, which is then compared with a preset error threshold. When the weighted absolute sum is less than the preset error threshold, a migration confirmation signal is output, and the process segment switching is automatically executed. The pH deviation and temperature deviation refer to the differences between the current detection value and the pH target and temperature target corresponding to the process segment, respectively.

4. The intelligent control system for an automated reaction vessel for precipitating ammonium tetramolybdate according to claim 1, characterized in that, Perform aggregate tracking control of the pH master loop, including: Step 11: When the pH is higher than the pH target, it is defined as a positive deviation; when the pH is lower than the pH target, it is defined as a negative deviation; when the pH is equal to the pH target, the pH deviation is zero. Step 12: Multiply the pH deviation by the fixed gain constant to obtain the valve position change rate. When the pH deviation is positive, increase the valve position opening; when the pH deviation is negative, decrease the valve position opening; when the pH deviation is zero, keep the valve position unchanged. Step 13: Within a fixed sampling period, calculate the product of the valve position change rate and the sampling period time, and add it to the valve position opening of the previous sampling period to obtain the updated valve position opening.

5. The intelligent control system for an automated reaction vessel for precipitating ammonium tetramolybdate according to claim 1, characterized in that, The acid addition rate is controlled by adjusting the slope of the valve position change based on the monitored values, and valve position limiting is applied, including: Step 21: Use the product of temperature deviation and temperature compensation coefficient as a correction coefficient to linearly correct the valve position change rate. Step 22: When the temperature deviation is positive, decrease the valve position change rate and reduce the acid addition rate; when the temperature deviation is negative, increase the valve position change rate and increase the acid addition rate; when the temperature deviation is zero, keep the valve position change rate and acid addition rate constant. The acid addition rate is proportional to the valve position change rate. Step 23: Apply limiting constraints to the valve position opening degree and the valve position change rate respectively, limit the valve position opening degree to between the preset minimum opening degree and the preset maximum opening degree, and limit the absolute value of the valve position change rate to not exceed the maximum allowable change rate. When the valve position opening degree or the valve position change rate touches the limit value, soft limiting control is automatically activated. The soft limiting control means gradually reducing the valve position change rate by proportional decrease.

6. The intelligent control system for an automated reaction vessel for precipitating ammonium tetramolybdate according to claim 1, characterized in that, Determine the required alkali solution volume and feeding time for the re-dissolution process, including: Step 41: Obtain the effective volume of the reactor, the current pH, the target pH for reconstitution, and the equivalent concentration of the alkaline solution. Calculate the pH difference based on the difference between the current pH and the target pH for reconstitution. Divide the product of the effective volume of the reactor and the pH difference for reconstitution by the equivalent concentration of the alkaline solution and multiply by the buffer compensation coefficient to determine the alkaline solution dispensing volume. When the pH difference for reconstitution is greater than zero, perform reconstitution dispensing. Step 42: Calculate the basic feeding time based on the ratio of the maximum flow rate of the feeding pipeline to the alkali solution feeding volume, and correct the basic feeding time with a smoothing coefficient to obtain the corrected feeding time. Then, perform the alkali solution feeding operation according to the segmented rate curves of slow start, constant speed, and slow stop respectively. Step 43: When the current pH reaches the target pH for reconstitution and the pH change rate is lower than the set change rate threshold, maintain constant temperature and constant speed stirring, keep the feeding terminated state for the third preset time, close the alkali valve after the end of the holding period and output a reconstitution completion signal.

7. The intelligent control system for an automated reaction vessel for precipitating ammonium tetramolybdate according to claim 1, characterized in that, Determine the reflux ratio and reflux the slurry from the correction section to the transition section according to the reflux ratio. The remainder enters the separation and washing process, including: Step 51: Calculate the difference between the fine grain ratio and the target fine grain ratio to obtain the fine grain ratio deviation. Then, correct the basic reflux ratio by multiplying the basic reflux ratio by the fine grain ratio deviation to determine the reflux ratio. When the fine grain ratio is higher than the target fine grain ratio, increase the reflux ratio; when the fine grain ratio is lower than the target fine grain ratio, decrease the reflux ratio. Step 52: Determine the reflux flow rate based on the product of the reflux ratio and the total discharge flow rate, and reflux the corrective section slurry to the transition section according to the reflux flow rate, while the remaining part is separated and washed; Step 53: During the reflux process, monitor the liquid level difference between the reflux section and the transition section. When the liquid level difference exceeds the preset liquid level threshold, automatically adjust the reflux pump speed.

8. The intelligent control system for an automated reaction vessel for precipitating ammonium tetramolybdate according to claim 7, characterized in that, When the refluxing quantitative execution module and the continuous reflux adjustment module work simultaneously, the sum of the current alkali supply volume and the reflux flow rate is calculated and compared with the effective volume of the reactor. If the ratio of the former to the latter exceeds the first preset ratio, the subsequent reflux start time is automatically delayed.

9. The intelligent control system for an automated reaction vessel for precipitating ammonium tetramolybdate according to claim 1, characterized in that, The process of calculating the precipitation rate includes: Step 61: Subtract the product of the feed flow rate and its corresponding molybdenum concentration from the product of the discharge flow rate and its corresponding molybdenum concentration in the mother liquor, and then divide by the effective volume of the reactor to obtain the precipitation rate for the current cycle; the precipitation rate reflects the instantaneous material balance state of molybdenum in the system. Step 62: Calculate the absolute difference between the sedimentation rate of the current cycle and the sedimentation rate of the previous cycle, compare the absolute difference with the preset rate threshold, and generate a stability determination result. Step 63: When the absolute difference is greater than the preset rate threshold, it is determined to be unstable. The acid addition rate of the pH main circuit is automatically adjusted according to the precipitation rate of the current cycle and the precipitation rate of the previous cycle. If the precipitation rate of the current cycle is large, the acid addition rate is reduced; otherwise, the acid addition rate is increased. When the stability determination result is stable, the acid addition rate is kept unchanged.

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