A method for cyclic feeding control based on multi-charge level meter interlocking

Abstract

The application discloses a kind of based on the interlocking of multiple material level meter circulation feed control method, belong to water treatment automatic dosing technical field.The existing PAM dosing system relies on artificial time feed or single liquid level trigger, easy to be blocked by reagent moisture absorption, negative pressure intermittent disturbance leads to feed interruption or equipment idling.The application is respectively provided with material level meter in storage, intermediate bunker and water tank, and negative pressure air conveying cycle is controlled by PLC interlocking: when the material level of storage is lower than the feed start threshold and the feeding hopper has material source, automatically execute the "negative pressure suction-delayed shutdown-cyclone separation blow spray" medicine cycle;When the water tank material level is lower than the dosing start threshold and the storage material level is higher than the safe lower limit, automatically execute the "negative pressure conveying-delayed shutdown-back blow discharge" dosing cycle.In each cycle, the timing cooperation of blow spray solenoid valve and flap valve is introduced, to eliminate the pipe wall residue.The application replaces single time or liquid level trigger with multiple material level grading interlocking, realizes the closed-loop feed of anti-clogging, self-adapting load, significantly reduces artificial intervention and operating energy consumption.

Description

Technical Field

[0001] This invention relates to the field of automatic dosing technology in water treatment, and in particular to a circulating feeding control method based on multi-level meter interlocking. Background Technology

[0002] This invention relates to the field of automatic dosing technology in water treatment, specifically to a circulating feed control method based on multi-level meter interlocking. PAM (polyacrylamide), as a highly efficient flocculant, is widely used in water treatment, sludge dewatering, and other processes. The automation and precision of its dosing system directly affect the water treatment effect and operating costs. Existing automatic dosing systems are typically equipped with level detection devices. When a low level is detected in the silo, an alarm signal is issued, and manual confirmation is required before the negative pressure airflow conveyor can be activated to draw the dry powder into the silo. Simultaneously, some systems are equipped with a variable frequency motor-driven screw feeder, which automatically adjusts the dry powder dosage according to changes in the influent flow rate via a PLC controller to maintain a constant ratio, and stops feeding when the silo level reaches a high level. However, the feed control logic of these systems is relatively simple, typically using a single level trigger condition. They lack coordinated management of the dynamic relationships between multiple levels and cannot adapt to intermittent disturbances caused by powder moisture adsorption and pipeline residues during negative pressure conveying. This leads to frequent feed interruptions or equipment idling during actual operation.

[0003] A search revealed that Chinese patent CN103920409B discloses an online automatic preparation and dosing device for PAM solid reagents. This device uses a solid screw conveyor in conjunction with a frequency converter screw feeder, and automatically adjusts the dosing amount and solid reagent dosage based on the real-time feedback of the instantaneous flow signal of the reagent from the outlet flow meter, thereby improving the accuracy and reliability of reagent solution dosing. While this technical solution has certain advantages in terms of dosing accuracy and concentration control, its feeding process still relies on a continuous screw conveyor feeding method. The utilization of material level information is limited to triggering manual feeding with a low material level alarm, and it does not establish a closed-loop replenishment control mechanism with multi-material level interlocks. Furthermore, it fails to address the problem of supply interruption caused by pipeline residue and cyclone separator blockage during negative pressure pneumatic conveying. In addition, the screw structure used for conveying solid reagents in this solution, given the strong moisture adsorption characteristics of PAM powder, the continuous friction and compression between the screw blades and the powder easily exacerbates powder agglomeration and pipe wall adhesion. Long-term operation leads to a significant decrease in conveying efficiency, requiring frequent shutdowns for cleaning, thus affecting the overall continuous automation of the system.

[0004] While existing technologies, exemplified by CN103920409B, have made significant progress in the field of automatic PAM dosing, their continuous spiral conveying mode and single-level-triggered replenishment control logic still have significant shortcomings when facing complex issues such as the easy absorption of moisture and clogging of PAM powder and the intermittent nature of negative pressure conveying in actual working conditions. Specifically, existing technologies lack coordinated interlocking control between multiple level gauges in storage silos, intermediate silos, and water tanks, and cannot dynamically adjust the replenishment and dosing sequence according to the real-time status of each level, resulting in poor system adaptability under different working conditions. At the same time, during negative pressure pneumatic conveying, the surface of the cyclone separator bag is prone to material accumulation due to the adsorption of powder moisture. If a blow-jet unloading mechanism coordinated with the conveying process is not adopted, the negative pressure conveying efficiency will gradually decrease until complete blockage occurs. Although existing technologies mention the back-blowing function of the vacuum feeder, the back-blowing action lacks refined timing coordination and repetitive cycle design with the conveying sequence, making it difficult to effectively cope with high-intensity continuous operation scenarios. Furthermore, existing technologies do not incorporate the ultra-low level signal of the water tank into the interlocking protection of the downstream delivery pump. If the water tank's reagent is depleted while the delivery pump continues to operate, it will cause the pump body to run dry and be damaged. Therefore, how to construct a closed-loop feeding control method that can comprehensively utilize real-time information from multiple level gauges, achieve coordinated negative pressure conveying and blow-jet unloading, and possess adaptive anti-clogging capabilities is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] In view of the aforementioned existing problems, the present invention is proposed.

[0006] Therefore, this invention provides a circulating material replenishment control method based on multi-level gauge interlocking to solve problems such as poor system adaptability under different working conditions, difficulty in effectively coping with high-intensity continuous operation scenarios, and pump damage due to idling.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a cyclic material replenishment control method based on multi-level gauge interlocking, comprising the following steps: High-level, low-level, and ultra-low-level material gauges are installed in the storage silo, intermediate silo, and water tank, respectively, and all material gauge signals are connected to the PLC controller. When the PLC controller detects that the low-level material level gauge of the storage bin is triggered and there is a material source in the feeding hopper, it first closes the pressure holding solenoid valve in the pressure holding circuit, and then sequentially opens the feeding electric valve, the negative pressure fan and the feeding frequency converter to suck the PAM powder in the feeding hopper into the cyclone separator at the top of the storage bin through the negative pressure air pipe. After the feeding frequency converter runs for the preset suction time, the feeding frequency converter is turned off in sequence, the negative pressure fan is turned off after a delay, and then at least one cyclone separator blowing cycle is executed, that is, the flap solenoid valve is opened in sequence, the blowing waiting time is waited, the blowing solenoid valve is opened and the blowing holding time is maintained, the blowing solenoid valve is closed, and then the flap solenoid valve is closed, so as to blow the powder retained in the cyclone separator into the storage silo. When the PLC controller detects that the low-level level gauge of the water tank is triggered but the high-level level gauge of the storage silo is not triggered, the dosing cycle is executed: the dosing negative pressure fan is turned on, the feeding frequency converter and the storage silo discharge vibrator are started after a delay, and the powder in the storage silo is sucked into the cyclone separator at the top of the water tank through the dosing air pipe. After the feeding frequency converter runs for the preset dosing suction time, the feeding frequency converter is turned off in sequence, the dosing negative pressure fan is turned off after a delay, and then the blowing and spraying cycle of the water tank cyclone separator is executed. At the same time, the pneumatic vibrator at the water tank discharge port is linked to assist in unloading. During the dosing cycle, if the ultra-low level gauge of the water tank is triggered, the PLC controller outputs an interlock stop signal to the DCS system to stop the downstream delivery pump; if the high level gauge of the storage silo is triggered, the dosing cycle is paused. If the tuning fork low-position signal of the intermediate hopper is triggered and the hopper level is higher than the safety lower limit, the intermediate hopper will be automatically replenished.

[0008] As a preferred embodiment of the cyclic feeding control method based on multi-level meter interlocking described in this invention, in the feeding cycle, after the feeding frequency converter is turned off and before the negative pressure fan is turned off, a duct evacuation delay is inserted. The duct evacuation delay is 5 seconds long, which is used to ensure that the residual powder in the negative pressure duct is completely sucked into the cyclone separator before the normal pressure locking mechanism is activated. The blowing cycle is executed twice consecutively. The first blowing is used to remove the powder adhering to the surface of the cyclone separator filter bag, and the second blowing is used to completely blow the accumulated material at the bottom of the separator into the storage bin. In each blowing cycle, the blowing waiting time is 2 seconds and the blowing holding time is 1 second.

[0009] As a preferred embodiment of the cyclic feeding control method based on multi-level gauge interlocking described in this invention, the following is specified: In the dosing cycle, after starting the dosing negative pressure fan and before starting the feeding frequency converter, a duct pressure building delay of 5 seconds is set to allow the dosing duct to fully establish negative pressure before feeding begins; after turning off the feeding frequency converter and before turning off the dosing negative pressure fan, a tail material conveying delay of 5 seconds is set to allow all residual powder in the duct to be sent into the water tank cyclone separator; In the blowing and spraying cycle of the water tank cyclone separator, the waiting time is 5 seconds, the blowing and spraying hold time is 0.5 seconds, and simultaneously with the blowing and spraying cycle, the PLC controller drives the pneumatic vibrator at the water tank discharge port with the same time parameters, so that the powder falls smoothly from the separator into the small hopper below.

[0010] As a preferred embodiment of the cyclic feeding control method based on multi-level meter interlocking described in this invention, the following steps are taken: Before starting the feeding cycle, the PLC controller first detects the current material level percentage in the storage bin. Feeding is only allowed when the storage bin material level is below 90% and above the ultra-low threshold. During the feeding cycle, if the storage bin material level rises above 95%, the PLC controller immediately interrupts the current suction phase and exits the feeding mode after completing one full blowing cycle to prevent the storage bin from becoming too full. If the storage bin material level is below the ultra-low threshold of 10%, the PLC controller prohibits the start of the feeding cycle and issues an audible and visual alarm on the touch screen and remote APP, prompting the operator to manually feed the material immediately.

[0011] As a preferred embodiment of the cyclic feeding control method based on multi-level gauge interlocking described in this invention, the operating frequency of the feeding inverter is automatically adapted according to the humidity of the powder in the feeding hopper: within the first 3 seconds after the feeding inverter starts, the PLC controller judges the flow resistance of the powder by monitoring the pressure drop rate of the pressure sensor in the negative pressure duct; if the pressure drop rate is lower than the preset blockage threshold, it is determined that the powder is damp and clumped, and the PLC controller automatically reduces the frequency of the feeding inverter by 20% based on the current set value, while increasing the number of blowing cycles to three; if the pressure drop rate is normal, the original set frequency is maintained, and after each feeding cycle, the next inhalation time is dynamically corrected based on the average pressure fluctuation during this inhalation, with the correction range not exceeding ±15% of the original set value.

[0012] As a preferred embodiment of the cyclic replenishment control method based on multi-level gauge interlocking described in this invention, the pressure-holding solenoid valve, the pressure-relieving ball valve, and the gas tank pressure sensor constitute an independent pressure-holding interlocking circuit: when the PLC controller detects that the pressure in the gas tank is lower than 80 kPa and the system is not in a replenishment or dosing state, the pressure-holding solenoid valve is automatically opened to replenish gas until the pressure recovers to 120 kPa and then the pressure-holding solenoid valve is closed; when the pressure in the gas tank exceeds 130 kPa, the pressure-relieving ball valve is automatically opened to release pressure until the pressure drops to 50 kPa and then the pressure-relieving ball valve is closed; during the replenishment cycle or dosing cycle activation, the pressure-holding solenoid valve is forcibly closed, and the interlocking function of the pressure-relieving ball valve is temporarily suspended, and the pressure-holding logic is automatically restored after the cycle ends.

[0013] As a preferred embodiment of the circulating feeding control method based on multi-level gauge interlocking described in this invention, the following steps are taken: an ultrasonic level gauge is installed in the water tank to continuously detect the level of the polymer agent; the PLC controller controls the inverter speed of the polypropylene dosing device in a step-wise adjustment manner according to the deviation between the real-time level of the water tank and the set value: when the water tank level is lower than the low-level set value and the deviation exceeds 20%, the inverter operates at the maximum speed of 1500 rpm; when the level is between the low and middle levels, the inverter speed is adjusted linearly proportionally, specifically expressed as: speed (rpm) = (current level - low-level set value) / (middle-level set value - low-level set value) × (1500 - 600) + 600; when the deviation above the middle-level set value is less than 10%, the inverter operates at the minimum maintenance speed of 600 rpm; when the level touches the high-level set value, the inverter stops immediately and detects again after a 30-second delay; if the level is still higher than the high-level set value, a dosing pause request is sent to the DCS.

[0014] As a preferred embodiment of the cyclic replenishment control method based on multi-level meter interlocking described in this invention, in the blowing and spraying phase after each dosing cycle, the PLC controller automatically records the total running time and total amount of powder absorbed in this dosing cycle, and predicts the start time of the next replenishment cycle based on the ratio of the amount of powder remaining in the storage bin to the water tank consumption rate; if the prediction result indicates that replenishment needs to be started within the next 2 hours and the current storage bin level is below 40%, the PLC controller actively starts the replenishment cycle in advance and shortens the absorption time of this replenishment cycle to 70% of the standard absorption time, so as to replenish the powder in stages and avoid the cyclone separator from being overloaded at once; if the prediction result indicates that no replenishment is needed within the next 6 hours, the PLC controller enters a low-power polling mode, checks the level signal every 10 minutes, and shuts down the power supply of unnecessary frequency converters.

[0015] As a preferred embodiment of the cyclic feeding control method based on multi-level gauge interlocking described in this invention, in manual operation mode, the PLC controller transfers control of all motors, valves, and frequency converters to the manual touchscreen, but retains the interlocking protection function of the ultra-low level gauge. When the operator clicks the start button of any device on the manual screen, the PLC controller first checks whether the upstream level gauge corresponding to that device is in a safe state: if the feeding frequency converter is started, the storage bin level must be below 95%; if the conveying frequency converter is started, the storage bin level must be above 10% and the water tank level must be below the high-level set value. If any condition is not met, the PLC controller refuses to start and displays a red warning message on the touchscreen, while recording the violation in the event log, which includes the operation time, device name, and the unmet condition.

[0016] As a preferred embodiment of the cyclic feeding control method based on multi-level gauge interlocking described in this invention, the PLC controller establishes a remote monitoring channel with the Yunlian IoT platform through a 4G smart gateway, and displays the status of each level gauge, the frequency converter operating frequency, the negative pressure duct pressure value, and the current cycle stage in real time on the remote APP. When the remote APP user issues an "emergency dosing" command, the PLC controller first determines whether the ultra-low level gauge of the water tank has been triggered. If it has been triggered, it immediately disables all level interlocking conditions and forcibly starts the emergency dosing process: the feeding frequency converter runs continuously at maximum speed, while the interval time of the blowing and spraying cycle is shortened to half of the normal value, and a snapshot of the running status is pushed to the APP every 15 minutes. If the ultra-low level gauge of the water tank has not been triggered, the PLC controller refuses to execute the emergency dosing command and provides a prompt message "Conditions not met, please check the water tank level" on the APP.

[0017] In a second aspect, the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program is executed by the processor, it implements any step of the cyclic feeding control method based on multi-level gauge interlocking as described in the first aspect of the present invention.

[0018] Thirdly, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, it implements any step of the cyclic feeding control method based on multi-level gauge interlocking as described in the first aspect of the present invention.

[0019] The cyclic feeding control method based on multi-level gauge interlocking provided by this invention has the following significant advantages compared with the prior art.

[0020] First, this method completely changes the traditional single-level triggering or manual inspection replenishment mode by setting high-level, low-level, and ultra-low-level level gauges in the storage silo, intermediate silo, and water tank respectively, and connecting all level signals to the PLC controller for coordinated interlocking control. This achieves dynamic perception and graded response to each level of material. When the storage silo is triggered at a low level, the replenishment cycle is automatically executed. When the water tank is triggered at a low level and the storage silo level is safe, the dosing cycle is automatically executed. At the same time, the ultra-low-level signal directly interlocks and stops the downstream conveying pump, effectively avoiding equipment idling damage and material supply interruption accidents, and significantly improving the system's operational reliability and automation level.

[0021] Secondly, this invention introduces refined timing control and a multi-stage blowing and unloading mechanism in the drug replenishment and dosing cycles. Specifically, it includes setting duct emptying delay and pressure building delay before and after the negative pressure fan starts and stops, ensuring sufficient delivery of residual powder in the duct and establishment of negative pressure. After each inhalation, two cyclone separator blowing and spraying cycles are executed continuously (wait 2 seconds, blow and spray hold 1 second), and the pneumatic vibrator at the water tank discharge port is linked in the dosing cycle to assist unloading with the same timing parameters. This design effectively solves the industry problem of PAM powder adhering to the separator bag and pipe wall due to humidity adsorption, avoids the decrease in delivery efficiency caused by blockage, and greatly extends the continuous operation cycle of the system.

[0022] Furthermore, this invention uses a PLC controller to dynamically and adaptively adjust the frequency of the feeding inverter. Specifically, it judges the moisture level of the powder based on the pressure drop rate in the negative pressure duct, automatically reduces the frequency and increases the number of blows, and corrects the next intake time based on the average pressure fluctuation during each intake. This allows the system to adapt to different humidity levels and different batches of PAM powder, maintaining stable conveying efficiency without manual intervention. This overcomes the shortcomings of existing spiral conveyor structures that are prone to clumping and require frequent cleaning.

[0023] Furthermore, this invention proposes specific and feasible improvement solutions in areas such as pressure control, stepped dosing adjustment, predictive pre-replenishment, interlocking protection in manual mode, and permission judgment for remote APP emergency dosing. For example, it can perform segmented linear adjustment of the inverter speed based on the water tank level deviation, predict the timing of dosing based on the remaining amount in the storage tank and the consumption rate, and actively adjust the intake volume. Remote commands are only forcibly executed when the water tank is at an extremely low level. These functions not only improve energy efficiency and ease of operation and maintenance, but also avoid the risks caused by misoperation.

[0024] In summary, this invention organically combines multi-level interlocking, negative pressure timing control, adaptive blockage adjustment, and remote intelligent monitoring to form a complete, stable, and highly anti-interference closed-loop feeding control method. This significantly reduces the safety risks and labor intensity of manual high-altitude dosing, reduces downtime for cleaning due to powder blockage, and realizes the leap from "manual-assisted automation" to "full-condition adaptive intelligence" in the PAM automatic dosing system. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. 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.

[0026] Figure 1This is a flowchart of a cyclic feeding control method based on multi-level gauge interlocking in Example 1. Detailed Implementation

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0029] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0030] Example 1, referring to Figure 1 This is the first embodiment of the present invention, which provides a cyclic material replenishment control method based on multi-level gauge interlocking, including the following steps: High-level, low-level, and ultra-low-level material gauges are installed in the storage silo, intermediate silo, and water tank, respectively, and all material gauge signals are connected to the PLC controller. When the PLC controller detects that the low-level material level gauge of the storage bin is triggered and there is a material source in the feeding hopper, it first closes the pressure holding solenoid valve in the pressure holding circuit, and then sequentially opens the feeding electric valve, the negative pressure fan and the feeding frequency converter to suck the PAM powder in the feeding hopper into the cyclone separator at the top of the storage bin through the negative pressure air pipe. After the feeding frequency converter runs for the preset suction time, the feeding frequency converter is turned off in sequence, the negative pressure fan is turned off after a delay, and then at least one cyclone separator blowing cycle is executed, that is, the flap solenoid valve is opened in sequence, the blowing waiting time is waited, the blowing solenoid valve is opened and the blowing holding time is maintained, the blowing solenoid valve is closed, and then the flap solenoid valve is closed, so as to blow the powder retained in the cyclone separator into the storage silo. When the PLC controller detects that the low-level level gauge of the water tank is triggered but the high-level level gauge of the storage silo is not triggered, the dosing cycle is executed: the dosing negative pressure fan is turned on, the feeding frequency converter and the storage silo discharge vibrator are started after a delay, and the powder in the storage silo is sucked into the cyclone separator at the top of the water tank through the dosing air pipe. After the feeding frequency converter runs for the preset dosing suction time, the feeding frequency converter is turned off in sequence, the dosing negative pressure fan is turned off after a delay, and then the blowing and spraying cycle of the water tank cyclone separator is executed. At the same time, the pneumatic vibrator at the water tank discharge port is linked to assist in unloading. During the dosing cycle, if the ultra-low level gauge of the water tank is triggered, the PLC controller outputs an interlock stop signal to the DCS system to stop the downstream delivery pump; if the high level gauge of the storage silo is triggered, the dosing cycle is paused. If the tuning fork low-position signal of the intermediate hopper is triggered and the hopper level is higher than the safety lower limit, the intermediate hopper will be automatically replenished.

[0031] During the replenishment cycle, after the feed frequency converter is turned off and before the negative pressure fan is turned off, a duct is inserted for evacuation delay. The evacuation delay is 5 seconds long, which is used to ensure that the residual powder in the negative pressure duct is completely sucked into the cyclone separator before the normal pressure locking mechanism is activated. The blowing and spraying cycle is executed twice in a row. The first blowing and spraying is used to remove the powder adhering to the surface of the cyclone separator filter bag, and the second blowing and spraying is used to completely blow the accumulated material at the bottom of the separator into the storage bin. In each blowing and spraying cycle, the blowing and spraying waiting time is 2 seconds and the blowing and spraying holding time is 1 second.

[0032] During the dosing cycle, after turning on the dosing negative pressure fan and before starting the feeding frequency converter, a duct pressure building delay of 5 seconds is set to allow the dosing duct to fully build negative pressure before feeding begins. After turning off the feeding frequency converter and before turning off the dosing negative pressure fan, a tail material conveying delay of 5 seconds is set to allow all residual powder in the duct to be sent into the water tank cyclone separator. During the blowing and spraying cycle of the water tank cyclone separator, the waiting time is 5 seconds and the blowing and spraying hold time is 0.5 seconds. Simultaneously with this blowing and spraying cycle, the PLC controller drives the pneumatic vibrator at the water tank discharge port with the same time parameters, so that the powder falls smoothly from the separator into the small hopper below.

[0033] Before starting the replenishment cycle, the PLC controller first checks the current material level percentage in the storage bin. Replenishment is only allowed when the material level in the storage bin is below 90% and above the ultra-low threshold. During the replenishment cycle, if the material level in the storage bin rises above 95%, the PLC controller immediately interrupts the current suction phase and exits the replenishment mode after completing one full blow-spray cycle to prevent the storage bin from becoming too full. If the material level in the storage bin is below the ultra-low threshold of 10%, the PLC controller prohibits the start of the replenishment cycle and issues an audible and visual alarm on the touch screen and remote APP, prompting the operator to manually add material immediately.

[0034] The operating frequency of the feeding inverter is automatically adapted to the humidity of the powder in the feeding hopper: within the first 3 seconds after the feeding inverter starts, the PLC controller judges the flow resistance of the powder by monitoring the pressure drop rate of the pressure sensor in the negative pressure air duct; if the pressure drop rate is lower than the preset blockage threshold, it is judged that the powder is damp and clumped, and the PLC controller automatically reduces the frequency of the feeding inverter by 20% based on the current setting value, while increasing the number of blowing and spraying cycles to three; if the pressure drop rate is normal, the original setting frequency is maintained, and after each replenishment cycle, the next inhalation time is dynamically corrected based on the average pressure fluctuation during this inhalation, with the correction range not exceeding ±15% of the original setting value.

[0035] The pressure-holding solenoid valve, the pressure-relieving ball valve, and the gas tank pressure sensor form an independent pressure-holding interlock circuit: When the PLC controller detects that the pressure in the gas tank is lower than 80 kPa and the system is not in a replenishment or dosing state, it automatically opens the pressure-holding solenoid valve to replenish gas until the pressure recovers to 120 kPa and then closes the pressure-holding solenoid valve; when the pressure in the gas tank exceeds 130 kPa, it automatically opens the pressure-relieving ball valve to release pressure until the pressure drops to 50 kPa and then closes the pressure-relieving ball valve; during the replenishment or dosing cycle, the pressure-holding solenoid valve is forcibly closed, and the interlock function of the pressure-relieving ball valve is temporarily suspended, and the pressure-holding logic is automatically restored after the cycle ends.

[0036] An ultrasonic level gauge is installed in the water tank to continuously detect the level of the polymer reagent. The PLC controller controls the inverter speed of the polypropylene dosing device in a step-by-step adjustment method based on the deviation between the real-time water level and the set value: when the water level is lower than the low set value and the deviation exceeds 20%, the inverter runs at the maximum speed of 1500 rpm; when the water level is between the low and middle levels, the inverter speed is adjusted linearly proportionally, specifically expressed as: speed (rpm) = (current water level - low set value) / (middle set value - low set value) × (1500 - 600) + 600; when the deviation above the middle set value is less than 10%, the inverter runs at the minimum maintenance speed of 600 rpm; when the water level reaches the high set value, the inverter stops immediately and checks again after a 30-second delay. If the water level is still higher than the high set value, a dosing pause request is sent to the DCS.

[0037] During the blowing and spraying phase after each dosing cycle, the PLC controller automatically records the total running time and total amount of powder inhaled for this dosing cycle. Based on the ratio of the remaining powder in the storage bin to the water tank consumption rate, it predicts the start time of the next dosing cycle. If the prediction indicates that dosing needs to be started within the next 2 hours and the current storage bin level is below 40%, the PLC controller proactively starts the dosing cycle in advance and shortens the inhalation time of this dosing cycle to 70% of the standard inhalation time to add powder in stages and avoid overloading the cyclone separator at once. If the prediction indicates that no dosing is needed within the next 6 hours, the PLC controller enters a low-power polling mode, checks the level signal every 10 minutes, and shuts down the power supply of unnecessary frequency converters.

[0038] In manual operation mode, the PLC controller delegates control of all motors, valves, and frequency converters to the touchscreen manual interface, but retains the interlock protection function of the ultra-low level gauge. When the operator clicks the start button of any device on the manual interface, the PLC controller first checks whether the upstream level gauge corresponding to that device is in a safe state: if the feed frequency converter is started, the silo level must be below 95%; if the delivery frequency converter is started, the silo level must be above 10% and the water tank level must be below the high-level set value. If any condition is not met, the PLC controller refuses to start the device and displays a red warning message on the touchscreen, while recording the violation in the event log, which includes the operation time, device name, and the condition not met.

[0039] The PLC controller establishes a remote monitoring channel with the Yunlian IoT platform through a 4G smart gateway. The status of each level gauge, the frequency converter's operating frequency, the negative pressure duct pressure, and the current cycle stage are displayed in real time on the remote APP. When the remote APP user issues an "emergency dosing" command, the PLC controller first checks if the ultra-low level gauge in the water tank has been triggered. If it has, it immediately disables all level interlock conditions and forcibly starts the emergency dosing process: continuously running the feeding frequency converter at maximum speed, while shortening the interval between blow-jet cycles to half the normal value, and pushing a snapshot of the operating status to the APP every 15 minutes. If the ultra-low level gauge in the water tank has not been triggered, the PLC controller refuses to execute the emergency dosing command and displays a message on the APP: "Conditions not met, please check the water tank level."

[0040] Example 2 is the second embodiment of the present invention. This embodiment provides a cyclic material replenishment control method based on multi-level gauge interlocking. The workflow and specific implementation of this embodiment are as follows: Before the system is put into operation, the hardware installation and wiring must be completed first: High-level, low-level, and ultra-low-low-level gauges are installed on the side walls of the storage silo from top to bottom. A tuning fork-type low-level gauge is installed on the side wall of the intermediate silo (i.e., the polypropylene silo). An ultrasonic level gauge (with high, low, and ultra-low-low level detection functions) is installed on the top of the water tank. The signal lines of all level gauges are connected to the digital input module of a Siemens S7-1200 PLC. Simultaneously, the feeding inverter at the bottom of the feeding hopper, the feeding inverter and vibrator at the storage silo discharge port, and the negative pressure fans (including the supplementary negative pressure fan B) are also connected. 201 and dosing negative pressure fan B 301) All electric valves and solenoid valves (including feeding electric valves, flap solenoid valves, blowing solenoid valves, pressure holding solenoid valves, pressure relief ball valves, etc.) are connected to the PLC's digital output module and analog output module via intermediate relays and contactors. The PLC controller has pre-programmed dosing function block FC3 and dosing function block FC4, and various parameters (including suction time, interval time, blowing / spray waiting time, blowing / spray holding time, etc.) are set on the KTP700 touchscreen. After the system is powered on, the PLC first self-checks the communication status of all peripherals. If there are no faults, it enters automatic standby mode and reads the current status of each level gauge in real time.

[0041] The workflow begins: The PLC controller cyclically scans the low-level indicator signal of the storage silo every 200 milliseconds. When the operator adds bagged PAM powder to the stainless steel feeding hopper on the ground and manually opens the valve in front of the negative pressure fan, the powder in the storage silo is gradually consumed. When the silo level drops to trigger the low-level indicator, the PLC detects the rising edge of this signal and simultaneously confirms the presence of a powder source in the feeding hopper (via a proximity switch at the bottom of the hopper or a manual confirmation signal). At this point, the first step of the replenishment cycle is immediately executed: closing the pressure-holding solenoid valve in the pressure-holding circuit to prevent the pressure-holding action from interfering with the negative pressure delivery during replenishment. Subsequently, the PLC issues commands sequentially: opening the feeding electric valve (opening the passage between the negative pressure duct and the feeding hopper), and starting the replenishment negative pressure fan B. 201. After a 2-second delay, the feeding inverter is activated (driving the quantitative rotary motor at the bottom of the feeding hopper). The PAM powder in the feeding hopper is drawn into the cyclone separator at the top of the storage silo through the duct under negative pressure. The powder settles within the separator, and fine dust is filtered by the filter bags. The PLC's internal timer begins recording the operating time of the feeding inverter. When the preset suction time is reached (e.g., 60 seconds, which can be adjusted on the touchscreen according to the powder characteristics), the PLC first issues a stop command to shut down the feeding inverter, then delays for 5 seconds (this is the duct emptying delay to ensure that any remaining powder in the duct completely enters the cyclone separator before the duct locking mechanism activates), and then shuts down the replenishment negative pressure fan. Next, the PLC automatically executes two consecutive cyclone separator blowing cycles: During the first blowing cycle, the flap solenoid valve is opened to connect the bottom channel of the separator to the storage chamber, and a 2-second waiting period is passed. Then, the blowing solenoid valve is opened, and compressed air is blown in reverse through the nozzles onto the surface of the filter bag, maintained for 1 second (blowing hold time), and then the blowing solenoid valve is closed. The flap solenoid valve is then closed. The second blowing cycle repeats the above process. These two blowing cycles blow all the powder adsorbed on the filter bag and the powder accumulated at the bottom of the separator into the storage chamber, completing one replenishment cycle. After the replenishment cycle is completed, the pressure-holding solenoid valve does not automatically reset. The operator needs to manually press the pressure-holding function key according to the air tank pressure. However, the system will close the pressure-holding solenoid valve again when the next replenishment cycle is started.

[0042] As the level of the polymer reagent used for flocculation in the tank gradually decreases, triggering the low-level indicator, the PLC detects this signal and simultaneously confirms that the high-level indicator in the storage silo has not been triggered (i.e., the silo is not full). It then automatically executes the dosing cycle. The specific steps of the dosing cycle are as follows: First, turn on the dosing negative pressure fan B. 301. After a 5-second delay (pressure build-up delay in the ductwork to ensure sufficient negative pressure is established in the long ductwork from the storage bin to the water tank), the feeding frequency converter is started (driving the storage bin discharge screw) and the storage bin discharge vibrator is started simultaneously. The powder in the storage bin is pushed out by the screw and then drawn into the cyclone separator at the top of the water tank by the negative pressure airflow through the dosing duct. The feeding frequency converter runs for the preset dosing suction time (e.g., 20 seconds). After the time is up, the PLC first shuts down the feeding frequency converter, delays for 5 seconds (tail material conveying delay to send all remaining powder in the ductwork into the separator), and then shuts down the dosing negative pressure fan. The following steps are executed: the blowing and spraying cycle of the cyclone separator in the water tank is performed: the flap solenoid valve is opened, and a 5-second wait is allowed (this waiting time is relatively long to allow some of the powder in the separator to fall naturally), the blowing and spraying solenoid valve is opened and held for 0.5 seconds, then closed, and finally the flap solenoid valve is closed. Simultaneously with this blowing and spraying cycle, the PLC drives the pneumatic vibrator at the water tank discharge port with the same time parameters (5-second wait, 0.5-second hold), using vibration to assist the powder in falling from the separator into the intermediate hopper (i.e., the polypropylene hopper) below. The intermediate hopper is equipped with a tuning fork low-level level gauge. When the powder in the intermediate hopper is continuously drawn down by the water tank dosing device until it triggers the tuning fork low-level signal, if the PLC detects that the current level in the hopper is higher than the preset safety lower limit (e.g., higher than 30%), it automatically starts the intermediate hopper replenishment process. This process is similar to the logic of adding medicine to the water tank but on a smaller scale, and will not be described in detail here.

[0043] Throughout the entire dosing cycle, the PLC continuously monitors the ultra-low level gauge in the tank. If, for any reason (such as insufficient dosing or a sudden increase in downstream usage), the tank level drops to the ultra-low level, the PLC immediately outputs a hard-wired interlock stop signal to the DCS system, forcibly stopping the downstream delivery pump to prevent damage from dry running. Simultaneously, if the high-level gauge in the storage silo suddenly triggers during the dosing cycle (indicating the silo is full), the PLC will not immediately interrupt the ongoing suction phase. Instead, it will continue to complete the current suction time, performing a complete blow-jet cycle after suction is complete. Then, it exits the dosing mode and prevents the next dosing cycle from starting, until the silo level drops below the low level again.

[0044] In the specific implementation of the above workflow, various time parameters can be flexibly set on the touch screen: for example, the "replenishment time setting" in the feeding hopper settings corresponds to an inhalation time of 60 seconds, the "replenishment interval time setting" corresponds to the interval between two blows (in the actual program, the interval is 0, and two blows are executed consecutively), and the waiting and holding time of each solenoid valve. In the manual operation mode of the equipment, the operator can test each motor and valve individually, but the PLC still retains the ultra-low level interlock protection. When the feeding frequency converter is manually started, if the storage bin level is lower than 10% or the water tank level is higher than the high level setting, the PLC will refuse to start and pop up a warning. In terms of remote monitoring, the PLC is connected to the Yunlian IoT platform through the 4G smart gateway EG20. Managers can use a mobile APP to enter the username "Meigang Addition" and the password "MG_12348765" to view the status of each material level, the fan frequency, the pressure value, and the current cycle stage in real time. When an emergency occurs on-site (such as a surge in water treatment volume during forced wastewater discharge) and the water tank is at its lowest level, the "emergency dosing" command on the APP will take effect. This forces the PLC to continuously run the feeding inverter at maximum speed and halve the blowing interval to ensure rapid replenishment of the reagent. Through the above workflow and specific implementation methods, this invention achieves fully automatic, anti-clogging, and low-intervention cyclic feeding control under multi-level interlocking, significantly improving the operational stability and maintenance convenience of the PAM dosing system.

[0045] This embodiment also provides a computer device applicable to a cyclic material replenishment control method based on multi-level gauge interlocking, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the cyclic material replenishment control method based on multi-level gauge interlocking as proposed in the above embodiment. The computer device can be a terminal, comprising a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0046] This embodiment also provides a storage medium storing a computer program. When executed by a processor, the program implements a cyclic feeding control method based on multi-level meter interlocking as proposed in the above embodiments. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0047] In summary, the cyclic material replenishment control method based on multi-level gauge interlocking provided by this invention has the following significant advantages compared to existing technologies. First, by setting high-level, low-level, and ultra-low-level gauges in the storage silo, intermediate silo, and water tank respectively, and connecting all level signals to the PLC controller for coordinated interlocking control, this method completely changes the traditional single-level triggering or manual inspection replenishment mode, realizing dynamic perception and graded response of each level of material. When the storage silo is triggered at a low level, the replenishment cycle is automatically executed; when the water tank is triggered at a low level and the storage silo level is safe, the dosing cycle is automatically executed. At the same time, the ultra-low-level signal directly interlocks and stops the downstream conveying pump, effectively avoiding equipment idling damage and material supply interruption accidents, and significantly improving the system's operational reliability and automation level. Secondly, this invention introduces refined timing control and a multi-stage blowing and unloading mechanism in the drug replenishment and dosing cycles. Specifically, it includes setting duct emptying delay and pressure building delay before and after the negative pressure fan starts and stops, ensuring sufficient delivery of residual powder in the duct and establishment of negative pressure. After each inhalation, two cyclone separator blowing and spraying cycles are executed continuously (wait 2 seconds, blow and spray hold 1 second), and the pneumatic vibrator at the water tank discharge port is linked in the dosing cycle to assist unloading with the same timing parameters. This design effectively solves the industry problem of PAM powder adhering to the separator bag and pipe wall due to humidity adsorption, avoids the decrease in delivery efficiency caused by blockage, and greatly extends the continuous operation cycle of the system. Furthermore, this invention utilizes a PLC controller to dynamically and adaptively adjust the frequency of the feed inverter. Specifically, it determines the moisture level of the powder based on the pressure drop rate within the negative pressure duct, automatically reducing the frequency and increasing the number of sprays. Simultaneously, it adjusts the next intake time based on the average pressure fluctuation during each intake cycle. This allows the system to adapt to different humidity levels and batches of PAM powder, maintaining stable conveying efficiency without manual intervention, overcoming the shortcomings of existing spiral conveyor structures that are prone to clumping and require frequent cleaning. In addition, this invention proposes specific and feasible improvements in pressure control, stepped dosing adjustment, predictive pre-replenishment, interlocking protection in manual mode, and remote APP emergency dosing permission judgment. For example, it allows for segmented linear adjustment of the inverter speed based on the water tank level deviation, predicts replenishment timing based on the remaining amount in the storage tank and the consumption rate, and actively adjusts the intake volume. Remote commands are only forcibly executed when the water tank reaches extremely low levels. These functions improve energy efficiency and ease of maintenance while avoiding the risks associated with misoperation. In summary, this invention organically combines multi-level interlocking, negative pressure timing control, adaptive blockage adjustment, and remote intelligent monitoring to form a complete, stable, and highly anti-interference closed-loop feeding control method. This significantly reduces the safety risks and labor intensity of manual high-altitude dosing, reduces downtime for cleaning due to powder blockage, and realizes the leap from "manual-assisted automation" to "full-condition adaptive intelligence" in the PAM automatic dosing system.

[0048] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A cyclic feeding control method based on multi-level gauge interlocking, used in a PAM automatic dosing system, characterized in that, Includes the following steps: High-level, low-level, and ultra-low-level material gauges are installed in the storage silo, intermediate silo, and water tank, respectively, and all material gauge signals are connected to the PLC controller. When the PLC controller detects that the low-level material level gauge of the storage bin is triggered and there is a material source in the feeding hopper, it first closes the pressure holding solenoid valve in the pressure holding circuit, and then sequentially opens the feeding electric valve, the negative pressure fan and the feeding frequency converter to suck the PAM powder in the feeding hopper into the cyclone separator at the top of the storage bin through the negative pressure air pipe. After the feeding frequency converter runs for the preset suction time, the feeding frequency converter is turned off in sequence, the negative pressure fan is turned off after a delay, and then at least one cyclone separator blowing cycle is executed, that is, the flap solenoid valve is opened in sequence, the blowing waiting time is waited, the blowing solenoid valve is opened and the blowing holding time is maintained, the blowing solenoid valve is closed, and then the flap solenoid valve is closed, so as to blow the powder retained in the cyclone separator into the storage silo. When the PLC controller detects that the low-level level gauge of the water tank is triggered but the high-level level gauge of the storage silo is not triggered, the dosing cycle is executed: the dosing negative pressure fan is turned on, the feeding frequency converter and the storage silo discharge vibrator are started after a delay, and the powder in the storage silo is sucked into the cyclone separator at the top of the water tank through the dosing air pipe. After the feeding frequency converter runs for the preset dosing suction time, the feeding frequency converter is turned off in sequence, the dosing negative pressure fan is turned off after a delay, and then the blowing and spraying cycle of the water tank cyclone separator is executed. At the same time, the pneumatic vibrator at the water tank discharge port is linked to assist in unloading. During the dosing cycle, if the ultra-low level gauge of the water tank is triggered, the PLC controller outputs an interlock stop signal to the DCS system to stop the downstream delivery pump; if the high level gauge of the storage silo is triggered, the dosing cycle is paused. If the tuning fork low-position signal of the intermediate silo is triggered and the silo level is higher than the safety lower limit, the intermediate silo will be automatically replenished.

2. The cyclic material replenishment control method based on multi-level gauge interlocking as described in claim 1, characterized in that: In the replenishment cycle, after the feed frequency converter is turned off and before the negative pressure fan is turned off, a duct is inserted for evacuation delay. The evacuation delay is 5 seconds long, which is used to ensure that the residual powder in the negative pressure duct is completely sucked into the cyclone separator before the normal pressure locking mechanism is activated. The blowing and spraying cycle is executed twice in a row. The first blowing and spraying is used to remove the powder adhering to the surface of the cyclone separator filter bag, and the second blowing and spraying is used to completely blow the accumulated material at the bottom of the separator into the storage bin. In each blowing and spraying cycle, the blowing and spraying waiting time is 2 seconds and the blowing and spraying holding time is 1 second.

3. The cyclic feeding control method based on multi-level gauge interlocking as described in claim 2, characterized in that: In the dosing cycle, after turning on the dosing negative pressure fan and before starting the feeding frequency converter, a duct pressure building delay of 5 seconds is set to allow the dosing duct to fully build negative pressure before feeding begins. After turning off the feeding frequency converter and before turning off the dosing negative pressure fan, a tail material conveying delay of 5 seconds is set to allow all residual powder in the duct to be sent into the water tank cyclone separator. In the blowing cycle of the water tank cyclone separator, the waiting time is 5 seconds and the blowing hold time is 0.5 seconds. Simultaneously with this blowing cycle, the PLC controller drives the pneumatic vibrator at the water tank discharge port with the same time parameters, so that the powder falls smoothly from the separator into the small hopper below.

4. The cyclic feeding control method based on multi-level gauge interlocking as described in claim 3, characterized in that: Before starting the replenishment cycle, the PLC controller first checks the current material level percentage in the storage bin. Replenishment is only allowed when the material level in the storage bin is below 90% and above the ultra-low threshold. During the replenishment cycle, if the material level in the storage bin rises above 95%, the PLC controller immediately interrupts the current suction phase and exits the replenishment mode after completing one full blow-spray cycle to prevent the storage bin from becoming too full. If the material level in the storage bin is below the ultra-low threshold of 10%, the PLC controller prohibits the start of the replenishment cycle and issues an audible and visual alarm on the touch screen and remote APP, prompting the operator to manually add material immediately.

5. The cyclic feeding control method based on multi-level gauge interlocking as described in claim 4, characterized in that: The operating frequency of the feeding inverter is automatically adapted to the humidity of the powder in the feeding hopper: within the first 3 seconds after the feeding inverter starts, the PLC controller judges the flow resistance of the powder by monitoring the pressure drop rate of the pressure sensor in the negative pressure air duct; if the pressure drop rate is lower than the preset blockage threshold, it is judged that the powder is damp and clumped, and the PLC controller automatically reduces the frequency of the feeding inverter by 20% based on the current setting value, while increasing the number of blowing and spraying cycles to three; if the pressure drop rate is normal, the original setting frequency is maintained, and after each replenishment cycle, the next inhalation time is dynamically corrected based on the average pressure fluctuation during this inhalation, with the correction range not exceeding ±15% of the original setting value.

6. The cyclic material replenishment control method based on multi-level gauge interlocking as described in claim 5, characterized in that: The pressure-holding solenoid valve, the pressure-relieving ball valve, and the gas tank pressure sensor constitute an independent pressure-holding interlocking circuit: when the PLC controller detects that the pressure in the gas tank is lower than 80 kPa and the system is not in a replenishment or dosing state, it automatically opens the pressure-holding solenoid valve to replenish gas until the pressure recovers to 120 kPa and then closes the pressure-holding solenoid valve; when the pressure in the gas tank exceeds 130 kPa, it automatically opens the pressure-relieving ball valve to release pressure until the pressure drops to 50 kPa and then closes the pressure-relieving ball valve; during the replenishment or dosing cycle, the pressure-holding solenoid valve is forcibly closed, and the interlocking function of the pressure-relieving ball valve is temporarily suspended, and the pressure-holding logic is automatically restored after the cycle ends.

7. The cyclic material replenishment control method based on multi-level gauge interlocking as described in claim 6, characterized in that: An ultrasonic level gauge is installed in the water tank to continuously detect the level of the polymer reagent. The PLC controller controls the inverter speed of the polypropylene dosing device in a step-by-step adjustment method based on the deviation between the real-time water level and the set value: when the water level is lower than the low set value and the deviation exceeds 20%, the inverter runs at the maximum speed of 1500 rpm; when the water level is between the low and middle levels, the inverter speed is adjusted linearly proportionally, specifically expressed as: speed (rpm) = (current water level - low set value) / (middle set value - low set value) × (1500 - 600) + 600; when the deviation above the middle set value is less than 10%, the inverter runs at the minimum maintenance speed of 600 rpm; when the water level reaches the high set value, the inverter stops immediately and checks again after a 30-second delay. If the water level is still higher than the high set value, a dosing pause request is sent to the DCS.

8. The cyclic feeding control method based on multi-level gauge interlocking as described in claim 7, characterized in that: During the blowing and spraying phase after each dosing cycle, the PLC controller automatically records the total running time and total amount of powder inhaled for this dosing cycle. Based on the ratio of the remaining powder in the storage bin to the water tank consumption rate, it predicts the start time of the next dosing cycle. If the prediction indicates that dosing needs to be started within the next 2 hours and the current storage bin level is below 40%, the PLC controller proactively starts the dosing cycle in advance and shortens the inhalation time of this dosing cycle to 70% of the standard inhalation time to add powder in stages and avoid overloading the cyclone separator at once. If the prediction indicates that no dosing is needed within the next 6 hours, the PLC controller enters a low-power polling mode, checks the level signal every 10 minutes, and shuts down the power supply of unnecessary frequency converters.

9. The cyclic material replenishment control method based on multi-level gauge interlocking as described in claim 8, characterized in that: In manual operation mode, the PLC controller delegates control of all motors, valves, and frequency converters to the touchscreen manual interface, but retains the interlock protection function of the ultra-low level gauge. When the operator clicks the start button of any device on the manual interface, the PLC controller first checks whether the upstream level gauge corresponding to that device is in a safe state: if the feed frequency converter is started, the silo level must be below 95%; if the delivery frequency converter is started, the silo level must be above 10% and the water tank level must be below the high-level set value. If any condition is not met, the PLC controller refuses to start the device and displays a red warning message on the touchscreen, while recording the violation in the event log, which includes the operation time, device name, and the condition not met.

10. The cyclic feeding control method based on multi-level gauge interlocking as described in claim 9, characterized in that: The PLC controller establishes a remote monitoring channel with the Yunlian IoT platform through a 4G smart gateway. The status of each level gauge, the frequency converter's operating frequency, the negative pressure duct pressure, and the current cycle stage are displayed in real time on the remote APP. When the remote APP user issues an "emergency dosing" command, the PLC controller first checks if the ultra-low level gauge in the water tank has been triggered. If it has, it immediately disables all level interlock conditions and forcibly starts the emergency dosing process: continuously running the feeding frequency converter at maximum speed, while shortening the interval between blow-jet cycles to half the normal value, and pushing a snapshot of the operating status to the APP every 15 minutes. If the ultra-low level gauge in the water tank has not been triggered, the PLC controller refuses to execute the emergency dosing command and displays a message on the APP: "Conditions not met, please check the water tank level."

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