Lead smelting furnace body control circuit system and control method

Abstract

The invention relates to the technical field of lead melting equipment, in particular to a lead melting furnace body control circuit system and a control method. Comprising an electromagnetic induction heating module, a temperature detection module, a heat preservation layer heat loss monitoring module, a power grid parameter acquisition module, a central control unit and a man-machine interaction module, and the electromagnetic induction heating module is electrically connected with the central control unit and used for adjusting the heating power of a lead smelting furnace body according to a control signal output by the central control unit; the temperature detection module comprises at least three temperature sensors arranged in different areas in the furnace body and is used for collecting temperature data in the furnace body in real time and transmitting the temperature data to the central control unit; the heat-insulating layer heat loss monitoring module comprises a heat flow sensor and a heat-insulating layer temperature sensor and is used for acquiring the heat loss rate of the heat-insulating layer and the temperature difference between the inner wall and the outer wall of the heat-insulating layer and transmitting to the central control unit; according to the technical scheme of the lead smelting furnace, the heating efficiency can be fundamentally improved, and energy loss is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lead melting equipment, and in particular to a lead melting furnace body control circuit system and a control method. BACKGROUND

[0002] In the field of lead product production and processing, a lead melting furnace is a key device for realizing lead material melting, and its heating efficiency, running stability and safety directly affect production efficiency and operation safety. The existing lead melting furnace generally adopts a traditional resistance heating method, which realizes lead material melting by heating the furnace body through the self-heating of an electric heating tube. However, this heating method has a core problem: low heating efficiency and serious energy loss. Resistance heating belongs to contact heat transfer, and the heat generated by the electric heating tube needs to be conducted to the furnace body through multiple media. During the process, a large amount of heat is lost in the form of radiation, convection and the like, resulting in an electric energy to heat energy conversion efficiency of only 50%-70%. At the same time, in order to maintain the required temperature in the furnace, the device needs to be continuously operated at high power, which not only increases the electric energy consumption and production cost, but also accelerates the aging of the electric heating tube due to long-term high-temperature operation, shortening the service life of the device. In addition, the hysteresis of the heat transfer process makes the heating uniformity of the furnace body poor, and local overheating or insufficient heating easily occurs, affecting the melting quality of the lead material.

[0003] Based on the above problems, there is an urgent need for a lead melting furnace technical solution that can fundamentally improve the heating efficiency and reduce energy loss to meet the production needs of high efficiency and energy saving. SUMMARY

[0004] The purpose of the present application is to solve the shortcomings in the prior art and to provide a lead melting furnace body control circuit system, which comprises an electromagnetic induction heating module, a temperature detection module, a thermal loss monitoring module of a heat preservation layer, an electric grid parameter acquisition module, a central control unit and a man-machine interaction module. The electromagnetic induction heating module is electrically connected with the central control unit and is used for adjusting the heating power of the lead melting furnace body according to the control signal output by the central control unit. The temperature detection module comprises at least three temperature sensors arranged in different regions inside the furnace body, which are used for collecting temperature data inside the furnace body in real time and transmitting the temperature data to the central control unit. The thermal loss monitoring module of the heat preservation layer comprises a heat flow sensor and a heat preservation layer temperature sensor, which are used for collecting the thermal loss rate of the heat preservation layer and the temperature difference between the inner and outer walls of the heat preservation layer and transmitting the data to the central control unit. The electric grid parameter acquisition module comprises a current sensor, a voltage sensor and a harmonic detector, which are used for collecting real-time current, voltage and harmonic content of the electric grid and transmitting the data to the central control unit. The central control unit is in bidirectional communication with the temperature detection module, the heat loss monitoring module of the heat preservation layer, the power grid parameter acquisition module and the man-machine interaction module respectively, can dynamically adjust the output power, start / stop timing and working frequency of the electromagnetic induction heating module according to the received temperature data, heat loss data and power grid parameters, so as to realize efficient heating, uniform temperature control and power grid load protection of the lead melting furnace body, and the man-machine interaction module is used for inputting target temperature, heating time and the like and displaying furnace body working state information.

[0005] Preferably, the electromagnetic induction heating module comprises an IGBT inverter unit, a resonance capacitor group and an induction coil, the input end of the IGBT inverter unit is connected with a three-phase alternating current power supply, the output end is connected with the resonance capacitor group and the induction coil in series to form a resonance loop, and the control end of the IGBT inverter unit is connected with the central control unit, which can adjust the inverter frequency and output power according to the PWM signal output by the central control unit.

[0006] Further preferably, the temperature sensor used in the temperature detection module is a K-type thermocouple, the measurement range of the K-type thermocouple is 0-500℃, and the measurement accuracy is ±1℃, the three temperature sensors are arranged at the central position of the bottom of the furnace body, the middle position of the side wall of the furnace body and the edge position of the top of the furnace body respectively, and each temperature sensor is connected with the A / D conversion interface of the central control unit through a shielded cable.

[0007] Further preferably, the central control unit adopts an STM32H743 microprocessor, the STM32H743 microprocessor has a built-in floating point operation unit and a high-speed A / D converter, can realize real-time acquisition and processing of temperature data, heat loss data and power grid parameters, and has at least 4 PWM output interfaces and 8 GPIO interfaces, which are respectively used for connecting the control end of the electromagnetic induction heating module and each monitoring module.

[0008] Further preferably, the control algorithm built in the central control unit comprises a dynamic power adjustment algorithm, and the output power calculation formula of the algorithm is: ; Wherein, P is the output power of the electromagnetic induction heating module; K is a proportional coefficient, and the value range is 0.5-2.0; is the deviation of the actual temperature of the furnace body from the target temperature, = target temperature-actual temperature; is an integral coefficient, and the value range is 0.01-0.1; is the integral value of the temperature deviation within time t; is the differential coefficient, the value range is 0.1-1.0; dT / dt is the furnace body temperature change rate; is the thermal loss correction coefficient of the insulation layer, the value range is 0.005-0.02; H is the thickness of the insulation layer; is the temperature difference between the inner and outer walls of the insulation layer; is the maximum temperature deviation allowed by the furnace body.

[0009] Further preferably: the central control unit further has a soft start control algorithm built-in, for controlling the starting process of the electromagnetic induction heating module, and the starting current limit formula is: ; wherein, is the starting current at time t; is the maximum starting current allowed by the module; β is the current rise rate adjustment coefficient, the value range is 0.8-1.2; t is the starting time; τ is the soft starting time constant, the value range is 0.5-5 seconds; γ is the grid voltage correction coefficient, the value range is 0.1-0.3; is the real-time grid voltage; is the rated grid voltage.

[0010] Further preferably: the central control unit further has an energy efficiency optimization algorithm built-in, for real-time optimization of heating efficiency, and the energy efficiency correction formula is: ; wherein, is the optimized thermal efficiency; is the basic thermal efficiency, the value is 0.9-0.95; is the power correction coefficient, the value range is 0.05-0.2; P is the actual output power; is the rated power; THD is the total harmonic distortion rate of the grid; is the maximum allowed total harmonic distortion rate; κ is the temperature change rate correction coefficient, the value range is 0.02-0.1; is the furnace body temperature change rate; is the maximum allowed temperature change rate.

[0011] A lead melting furnace body control method, applied to the lead melting furnace body control circuit system of any one of the above, comprising S1: input the target temperature, insulation layer thickness and heating time parameters through the man-machine interaction module, and the central control unit initializes and detects each module to confirm that the temperature sensor, heat flow sensor and grid parameter acquisition module are working normally; S2: The central control unit outputs a control signal to the electromagnetic induction heating module according to a soft start control algorithm, controls the starting process according to a starting current limiting formula, and gradually increases the starting current from 0 to a stable working current; S3: During the heating process, the central control unit receives temperature data transmitted by the temperature detection module, heat loss data transmitted by the heat loss monitoring module of the heat preservation layer, and power grid data transmitted by the power grid parameter acquisition module in real time, calculates the output power through a dynamic power adjustment algorithm, and adjusts the duty cycle of the PWM signal of the electromagnetic induction heating module, so that the furnace body temperature is maintained within the target temperature ± ΔTmax range; S4: The central control unit calculates the current thermal efficiency in real time according to the energy efficiency optimization formula of claim 7, and when the thermal efficiency is lower than × 0.9, the working frequency of the electromagnetic induction heating module is automatically adjusted to make the thermal efficiency rise to × 0.9 or above; S5: When the heating time reaches the set value or the furnace body temperature exceeds the target temperature + ΔTmax, the central control unit controls the electromagnetic induction heating module to gradually reduce the output power until the power is 0, and the heating process is completed.

[0012] Further preferably, in S3, when the temperature deviation of different regions of the furnace body exceeds 5℃, the central control unit adjusts the current distribution of different sections of the induction coil to control the temperature deviation of each region of the furnace body within 5℃, wherein the current distribution ratio of the induction coil section is determined according to the inverse square relationship of the temperature deviation of each region.

[0013] Further preferably, in S4, the specific way to adjust the working frequency of the electromagnetic induction heating module is: when the thermal efficiency is lower than × 0.9, the central control unit increases the working frequency by 5%-10% based on the current frequency, and if the adjusted thermal efficiency still does not meet the standard, it continues to increase by 5%-10%, until the thermal efficiency meets the standard or the working frequency reaches the maximum allowed frequency, which is 1.2 times the resonance frequency of the induction coil.

[0014] Technical effects: The present application solves the main problems of low heating efficiency and serious energy loss of the traditional lead melting furnace in the background technology by adopting the creative technical points of the electromagnetic induction heating module, multi-region temperature detection, heat loss monitoring of the heat preservation layer, power grid parameter acquisition and the cooperative work of the central control unit.

[0015] The electromagnetic induction heating realizes non-contact heating, reduces heat transfer loss; the multi-module data acquisition combined with intelligent algorithm dynamically adjusts the power, reduces useless energy consumption; the heat preservation layer monitoring reduces heat diffusion, significantly improves the heating efficiency and reduces the energy loss. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A control circuit block diagram of a lead melting furnace body according to the present application; Figure 2 A control method flow chart of a lead melting furnace body according to the present application. DETAILED DESCRIPTION

[0017] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0018] In the description of the present application, it should be understood that the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, in the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0019] The conventional lead melting furnace has the problems of low heating efficiency, poor temperature control accuracy, sensitivity to power grid fluctuations and poor heat preservation performance. For example, the heating module cannot accurately control the power according to the real-time situation in the furnace, resulting in waste of energy; a single temperature sensor cannot reflect the overall temperature distribution in the furnace, resulting in uneven temperature; when the power grid fluctuates, the equipment is easily damaged and unstable; the heat loss of the heat preservation layer is not monitored, and the heat preservation measures cannot be optimized in time.

[0020] Based on this, please refer to Figure 1The embodiment provides a lead melting furnace body control circuit system, which comprises an electromagnetic induction heating module, a temperature detection module, a thermal loss monitoring module of a heat preservation layer, a power grid parameter acquisition module, a central control unit and a man-machine interaction module. The electromagnetic induction heating module is electrically connected with the central control unit and is used for adjusting the heating power of the lead melting furnace body according to the control signal output by the central control unit. The temperature detection module comprises at least three temperature sensors arranged in different regions inside the furnace body and is used for collecting the temperature data inside the furnace body in real time and transmitting the temperature data to the central control unit. The thermal loss monitoring module of the heat preservation layer comprises a heat flow sensor and a heat preservation layer temperature sensor and is used for collecting the thermal loss rate of the heat preservation layer and the temperature difference between the inner wall and the outer wall of the heat preservation layer and transmitting the thermal loss rate and the temperature difference to the central control unit. The power grid parameter acquisition module comprises a current sensor, a voltage sensor and a harmonic detector and is used for collecting the real-time current, voltage and harmonic content of the power grid and transmitting the real-time current, voltage and harmonic content to the central control unit. The central control unit is in bidirectional communication with the temperature detection module, the thermal loss monitoring module of the heat preservation layer, the power grid parameter acquisition module and the man-machine interaction module, can dynamically adjust the output power, start / stop timing and working frequency of the electromagnetic induction heating module according to the received temperature data, thermal loss data and power grid parameters, so as to realize efficient heating, uniform temperature control and power grid load protection of the lead melting furnace body, and the man-machine interaction module is used for inputting target temperature, heating time and other parameters and displaying the working state information of the furnace body.

[0021] The scheme solves the problems of traditional lead melting furnace body heating, temperature control, power grid adaptation and heat preservation through multi-module cooperation, multi-region temperature detection, heat preservation layer thermal loss monitoring and power grid parameter acquisition, and the intelligent algorithm of the central control unit, and improves the comprehensive performance of the lead melting furnace body.

[0022] In the scheme, the multi-region temperature sensor can comprehensively obtain the temperature distribution in the furnace, provides a basis for accurate temperature control, the thermal loss monitoring module of the heat preservation layer can feedback the heat preservation condition in real time, so as to timely adjust the heating strategy and reduce heat loss, and the power grid parameter acquisition module enables the equipment to be self-adaptively adjusted according to the power grid condition, and guarantees stable operation. The electromagnetic induction heating module is accurately controlled by the central control unit, can realize efficient heating and avoids energy waste.

[0023] The man-machine interaction module facilitates the operation personnel to set parameters and monitor the state, and improves the operation convenience.

[0024] The traditional electromagnetic induction heating module is prone to generating an impact current when starting, causes damage to the equipment and the power grid, and is difficult to accurately match the heating requirements of different stages of the furnace body in the heating process, so that the heating efficiency is low and energy is wasted.

[0025] Therefore, the electromagnetic induction heating module comprises an IGBT inverter unit, a resonance capacitor group and an induction coil, the input end of the IGBT inverter unit is connected with a three-phase alternating current power supply, the output end is connected with the resonance capacitor group and the induction coil in series to form a resonance loop, and the control end of the IGBT inverter unit is connected with the central control unit, so that the inverter frequency and the output power can be adjusted according to the PWM signal output by the central control unit.

[0026] The scheme adjusts the inverter frequency and the output power flexibly by the IGBT inverter unit and the central control unit cooperating with each other through the PWM signal, solves the problems of large starting impact and poor heating matching degree of the traditional heating module, and improves the heating efficiency and the equipment stability. In the starting stage, the IGBT inverter unit can be controlled through the PWM signal to make the current slowly rise and avoid impact; in the heating process, the power is adjusted in real time according to the instruction of the central control unit to meet the requirements of different heating stages of the furnace body.

[0027] The traditional temperature detection module mainly uses single-point temperature measurement, cannot reflect the overall situation of the temperature field in the furnace, and has low sensor precision and poor reliability, is easily disturbed in a high-temperature and complex electromagnetic environment, and thus leads to inaccurate temperature data and affects the temperature control effect.

[0028] Therefore, the temperature sensor used in the temperature detection module is a K-type thermocouple, the measurement range of which is 0-500℃, and the measurement precision is ±1℃, three temperature sensors are arranged at the central position of the bottom of the furnace body, the middle position of the side wall of the furnace body and the edge position of the top of the furnace body respectively, and each temperature sensor is connected with the A / D conversion interface of the central control unit through a shielded cable.

[0029] The scheme solves the limitations of the traditional temperature detection by arranging multiple high-precision K-type thermocouples at key positions in the furnace and connecting them with shielded cables, and can accurately obtain the three-dimensional temperature distribution in the furnace to provide reliable data for accurate temperature control. The temperature sensors at the bottom, the side wall and the top can monitor the temperatures of different areas respectively, and the comprehensive data can reflect the overall temperature condition in the furnace; the high precision of the K-type thermocouple and the shielded cable can effectively resist interference and ensure accurate transmission of the temperature data to the central control unit.

[0030] The traditional central control unit has limited processing capacity and is difficult to quickly and accurately analyze and process a large amount of real-time data, leading to slow control response, inability to adjust the heating strategy in time according to the changes of the furnace body and the power grid, and insufficient number of interfaces and poor compatibility, making it difficult to effectively connect with various monitoring and execution modules.

[0031] Therefore, the central control unit adopts an STM32H743 microprocessor, which has a built-in floating point operation unit and a high-speed A / D converter, can realize real-time collection and processing of temperature data, heat loss data and power grid parameters, and has at least 4 PWM output interfaces and 8 GPIO interfaces, which are respectively used for connecting the control end of the electromagnetic induction heating module and each monitoring module.

[0032] The scheme uses the powerful operation and data processing capability of the STM32H743 microprocessor and rich interface resources to solve the performance bottleneck and interface problem of the traditional central control unit and realize efficient and intelligent control of the lead melting furnace body. The built-in floating point operation unit and high-speed A / D converter can quickly process various monitoring data, the 4-way PWM output interface can accurately control the electromagnetic induction heating module, and the 8-way GPIO interface facilitates connection of each monitoring module, ensuring smooth data interaction and control instruction transmission of the system.

[0033] The traditional lead melting furnace body control algorithm is simple and does not fully consider the comprehensive influence of factors such as furnace body temperature change dynamic characteristics, heat loss of the insulation layer and power grid fluctuation on the heating power, resulting in large temperature fluctuation during heating, low energy utilization rate and inability to realize efficient and stable lead melting operation.

[0034] Therefore, the control algorithm built in the central control unit includes a dynamic power regulation algorithm, and the output power calculation formula of the algorithm is: ; Wherein, P is the output power of the electromagnetic induction heating module; is a proportional coefficient, and the value range is 0.5-2.0; ΔT is the deviation of the actual temperature of the furnace body from the target temperature, ΔT=target temperature-actual temperature; is an integral coefficient, and the value range is 0.01-0.1; is the integral value of the temperature deviation within time t; is a differential coefficient, and the value range is 0.1-1.0; dT / dt is the temperature change rate of the furnace body; α is the insulation layer heat loss correction coefficient, and the value range is 0.005-0.02; H is the thickness of the insulation layer; is the temperature difference between the inner and outer walls of the insulation layer; is the maximum temperature deviation allowed by the furnace body.

[0035] In the above formula, the basic regulation term is a proportional coefficient, and the value range is 0.5-2.0, which is used to directly output the regulation power according to the current temperature deviation The greater the deviation, the more significant the power regulation amplitude, and the faster the response to the temperature deviation.

[0036] The integral compensation term ​is the integral coefficient, and its value range is 0.01-0.1. By accumulating and integrating the temperature deviation within time t, it eliminates the long-term steady-state deviation, avoids the temperature lag caused by system inertia, and ensures that the final temperature is stable at the target value.

[0037] Differential prediction term : is the differential coefficient, ranging from 0.1 to 1.0, based on the temperature change rate Predict temperature change trends, adjust power in advance, and suppress temperature overshoot. For example, when the temperature rises rapidly, reduce power in advance to avoid exceeding the target temperature.

[0038] Insulation correction factor : is the heat loss correction coefficient, the value range is 0.005-0.02, H is the thickness of the insulation layer, is the temperature difference between the inner and outer walls of the insulation layer, The maximum allowable temperature deviation. This factor modifies the differential term by quantifying the degree of heat loss in the insulation layer. When the insulation layer dissipates heat severely ( When the value is large, the correction factor decreases, reducing the inhibitory effect of the differential term and allowing higher power to compensate for heat loss; on the contrary, the adjustment accuracy of the differential term is enhanced, realizing dynamic adaptation of power control to the insulation state.

[0039] This solution utilizes a complex dynamic power regulation algorithm that comprehensively considers the impact of multiple factors on heating power, addressing the shortcomings of traditional control algorithms and achieving precise control of the lead melting furnace temperature and efficient energy utilization. Proportional, integral, and differential control mechanisms dynamically adjust power based on temperature deviation and rate of change. The insulation heat loss correction factor adjusts power based on the actual insulation layer conditions, ensuring that heating power more closely matches the actual furnace requirements, reducing temperature fluctuations and improving energy efficiency.

[0040] For example, traditional technical solutions have the following technical problems: when a traditional lead melting furnace is started, the starting current is too large and difficult to control, which can easily cause an impact on the power grid and affect the normal operation of other electrical equipment. At the same time, excessive starting current will shorten the service life of the equipment and increase maintenance costs. In addition, the impact of grid voltage fluctuations is not taken into account during the startup process. When the grid voltage is unstable, the starting current is prone to abnormalities, resulting in startup failure or equipment damage.

[0041] Based on this, the central control unit also has a built-in soft start control algorithm for controlling the startup process of the electromagnetic induction heating module. The startup current limiting formula is: ; in, is the starting current at time t; is the maximum starting current allowed for the module; β is the current rise rate adjustment coefficient, with a value range of 0.8-1.2; t is the starting time; is the soft starting time constant, with a value range of 0.5-5 seconds; is the grid voltage correction coefficient, with a value range of 0.1-0.3; is the real-time grid voltage; is the rated grid voltage. This scheme solves the problems of excessive starting current, large impact on the grid, and large influence of grid voltage fluctuations in the traditional starting method by introducing a soft starting control algorithm and the corresponding starting current limiting formula, and realizes the smooth starting of the lead furnace.

[0042] Numerator part describes the rising trend of the starting current over time, where has a value range of 0.8-1.2, adjusting the current rise rate, has a value range of 0.5-5 seconds, and is the soft starting time constant. The exponential function ensures that the current starts from 0 and grows slowly, avoiding sudden shocks, and the current rise amplitude at time t is controlled by the time constant and the rate coefficient, realizing the smooth characteristics of soft starting.

[0043] Denominator part : the grid voltage correction is introduced, has a value range of 0.1-0.3, and is the voltage correction coefficient, is the real-time grid voltage, is the rated voltage. When the grid voltage is higher than the rated value, increases, the denominator becomes larger, and the starting current is suppressed to prevent current over-limiting under high voltage; when the voltage is lower than the rated value, the denominator decreases, allowing the current to moderately increase to ensure the starting power, realizing adaptive adjustment of the grid.

[0044] Overall structure: the above ratio is scaled by the maximum starting current to ensure that the starting current is always within a safe range. The formula combines the time dimension current gradual control and real-time adaptation of the grid voltage, avoiding the current shock of traditional hard starting and solving the starting stability problem under grid fluctuations.

[0045] It is worth mentioning that: the grid voltage correction term is introduced in the formula, which corrects the starting current in real time. When the grid voltage is higher than the rated voltage, the denominator increases, and the starting current decreases accordingly, avoiding abnormal starting current due to excessively high voltage; when the grid voltage is lower than the rated voltage, the denominator decreases, reasonably controlling the current rise while ensuring starting. At the same time, the numerator part of the formula makes the starting current rise exponentially over time, avoiding sudden changes in current.

[0046] The technical effects achieved by the above embodiments include: effectively limiting the starting current, reducing the impact on the power grid, and ensuring the stable operation of the power grid and other equipment; prolonging the service life of the equipment and reducing the maintenance cost; when the voltage of the power grid fluctuates, smooth starting can still be achieved, the reliability and success rate of starting are improved, and it is ensured that the lead melting furnace can enter the working state stably and safely.

[0047] The traditional technical solution has the following technical problems: the heating efficiency of the traditional lead melting furnace is easily affected by factors such as output power, power grid harmonics, and temperature change rate, and lacks an effective energy efficiency optimization mechanism, resulting in serious energy waste during the heating process, unstable thermal efficiency, and inability to maintain a high level at all times, increasing the use cost; at the same time, it is difficult to dynamically adjust the thermal efficiency according to the real-time working condition, and when the thermal efficiency decreases, measures cannot be taken in time to restore it, affecting the lead melting efficiency.

[0048] Therefore, the central control unit also has an energy efficiency optimization algorithm built in, which is used to optimize the heating efficiency in real time, and the energy efficiency correction formula is: ; Wherein, is the optimized thermal efficiency; is the basic thermal efficiency, with a value of 0.9-0.95; is the power correction coefficient, with a value range of 0.05-0.2; P is the actual output power; is the rated power; THD is the total harmonic distortion rate of the power grid; is the maximum allowed total harmonic distortion rate; is the temperature change rate correction coefficient, with a value range of 0.02-0.1; is the furnace body temperature change rate; is the maximum allowed temperature change rate.

[0049] Basic efficiency : The value range is 0.9-0.95, which is the system reference thermal efficiency, ensuring that the starting point of the optimized efficiency is higher than that of the traditional resistance heating method.

[0050] Power correction term ( ): The value range is 0.05-0.2, which is the power coefficient; Reflects the square relationship between the actual power and the rated power. When the actual power is close to the rated power, this term increases, promoting efficiency improvement and avoiding efficiency loss during low-power operation; when the power deviates from the rated value, the correction amplitude decreases, preventing invalid energy consumption.

[0051] Power grid harmonic correction term ( ): THD is the total harmonic distortion rate of the power grid, is allowed. The lower the harmonic, the closer the term is to 1, the greater the positive contribution to efficiency; when the harmonic is excessive, the term decreases, triggering the system's harmonic suppression adjustment, reducing the efficiency loss caused by the harmonic.

[0052] Temperature change rate correction term (T) ): The value range is 0.02-0.1, which is the temperature coefficient, Reflects the ratio of the current temperature rise rate to the maximum allowed rate. Within a reasonable temperature rise range, the term is positive, improving efficiency; when the temperature rises too fast, the correction amplitude decreases, avoiding efficiency decline caused by local overheating.

[0053] This formula corrects through multiple factors, making The dynamic adaptation of power output, power grid quality and temperature rise state solves the problem of large single factor influence and poor stability of traditional heating efficiency, and realizes high-efficiency operation under all working conditions.

[0054] This scheme solves the problems of unstable thermal efficiency and difficulty in dynamic optimization of traditional lead melting furnaces by using built-in energy efficiency optimization algorithm and energy efficiency correction formula, realizing real-time optimization and improvement of heating efficiency. It is worth mentioning that: the formula considers the ratio of actual output power to rated power, total harmonic distortion rate of power grid and temperature change rate of furnace body, and dynamically adjusts the thermal efficiency through the synergistic effect of each correction term.

[0055] When the actual output power is close to the rated power and the power grid harmonic is small, the thermal efficiency correction term is positive, which helps to improve the thermal efficiency; when the temperature change rate is within a reasonable range, it also has a positive correction effect on the thermal efficiency.

[0056] The above embodiments achieve the following technical effects: the thermal efficiency can be optimized in real time according to the working condition, energy waste is reduced, and use cost is reduced; under different output power, power grid harmonic and temperature change rate conditions, the thermal efficiency can be kept at a high level, improving the energy utilization rate of the lead melting furnace; through dynamic adjustment of the thermal efficiency, the lead melting process is stable and efficient, and the overall working performance is improved.

[0057] The traditional technical scheme has the following technical problems: the control method of the traditional lead melting furnace lacks systematization and intelligentization, the starting process is not smooth, and it is easy to cause damage to the equipment and power grid; the power regulation in the heating process is not accurate, causing large fluctuations in the furnace temperature, which affects the quality of lead melting; the energy efficiency optimization mechanism is missing, and energy is wasted seriously; the stop process control is unreasonable, and the furnace body life is easily affected by sudden temperature changes.

[0058] Based on this, please refer to Figure 2The embodiment provides a lead melting furnace body control method, which is applied to the lead melting furnace body control circuit system and comprises the following steps: Initialization: target temperature, insulation layer thickness and heating time length parameters are input through a man-machine interaction module, and a central control unit initializes and detects each module, so that it is confirmed that a temperature sensor, a heat flow sensor and a power grid parameter acquisition module are in normal operation. Start control: the central control unit outputs a control signal to the electromagnetic induction heating module according to a soft start control algorithm, controls the start process according to the start current limiting formula in claim 6, and gradually increases the start current from 0 to a stable working current. Dynamic adjustment: in the heating process, the central control unit receives temperature data transmitted by a temperature detection module, heat loss data transmitted by an insulation layer heat loss monitoring module and power grid data transmitted by a power grid parameter acquisition module in real time, calculates output power through the dynamic power adjustment algorithm in claim 5, and adjusts the duty cycle of the PWM signal of the electromagnetic induction heating module, so that the furnace body temperature is maintained within the target temperature ± ΔTmax range. Energy efficiency optimization: the central control unit calculates the current thermal efficiency in real time according to the energy efficiency optimization formula in claim 7, and when the thermal efficiency is lower than × 0.9, the working frequency of the electromagnetic induction heating module is automatically adjusted, so that the thermal efficiency is restored to × 0.9 or above. Stop control: when the heating time length reaches a set value or the furnace body temperature exceeds the target temperature + ΔTmax, the central control unit controls the electromagnetic induction heating module to gradually reduce the output power until the power is 0, and the heating process is completed. The scheme realizes whole-process management from the initialization, start, dynamic adjustment, energy efficiency optimization to stop control, solves many problems of the traditional control method, and realizes intelligent and efficient operation of the lead melting furnace.

[0059] It is worth mentioning that the initialization step ensures that each module is in normal operation, and lays a foundation for subsequent control; the start control adopts a soft start algorithm to ensure smooth start; the dynamic adjustment realizes accurate temperature control by using various data; the energy efficiency optimization improves energy utilization in real time; and the stop control adopts a step-by-step power reduction mode to protect the furnace body. The technical effects achieved by the above embodiment include: the start process is smooth, the impact on the equipment and the power grid is reduced, and the service life of the equipment is prolonged; the temperature control is accurate during the heating process, the fluctuation is small, and the lead melting quality is improved; the energy efficiency is effectively optimized, and energy consumption is reduced; the stop process is smooth, the damage of temperature sudden change to the furnace body is avoided, and the working performance and reliability of the lead melting furnace are improved as a whole.

[0060] The traditional technical solution has the following technical problems: in the heating process of the traditional lead melting furnace, there is a large temperature deviation in different regions of the furnace body, which leads to uneven melting of the lead liquid and affects the product quality; and there is no effective temperature balancing adjustment mechanism, so the current distribution cannot be adjusted according to the temperature deviation of each region, and the temperature deviation continues to exist or even expands.

[0061] Therefore, in step 3, when the temperature deviation of different regions of the furnace body exceeds 5℃, the central control unit adjusts the current distribution of different sections of the induction coil to control the temperature deviation of each region of the furnace body within 5℃, wherein the current distribution ratio of the induction coil section is determined according to the inverse square relationship of the temperature deviation of each region. The scheme solves the problem of excessive temperature deviation of each region of the furnace body by establishing an inverse square relationship between the current distribution of the induction coil section and the temperature deviation of the region, and realizes balanced control of the temperature. It is worth mentioning that the use of the inverse square relationship enables the region with a larger temperature deviation to obtain relatively more current distribution, thereby speeding up the heating speed of the region and quickly reducing the temperature deviation; while the region with a smaller temperature deviation obtains less current distribution, avoiding excessive temperature. This targeted adjustment method is accurate and efficient, and can quickly control the temperature deviation of each region within a reasonable range.

[0062] The technical effects achieved by the above embodiments include: ensuring uniform temperature of each region of the furnace body, consistent melting quality of the lead liquid, and improving the product qualification rate; avoiding damage to the furnace body caused by excessive or insufficient local temperature, prolonging the service life of the furnace body; through precise current distribution adjustment, unnecessary energy consumption is reduced, energy utilization efficiency is improved, and the lead melting process is more stable and efficient.

[0063] The traditional technical solution has the following technical problems: in the energy efficiency optimization process of the traditional lead melting furnace, when the thermal efficiency is lower than the set threshold, there is no clear and effective working frequency adjustment method, the adjustment range is unreasonable, which may lead to the inability of the thermal efficiency to quickly recover, or the stable operation of the equipment is affected due to the excessive adjustment range; and there is no maximum allowed frequency limit, which may cause damage to the induction coil and other components due to excessive frequency.

[0064] Therefore, in step 4, the specific way to adjust the working frequency of the electromagnetic induction heating module is: when the thermal efficiency is lower than the set threshold, the working frequency of the electromagnetic induction heating module is adjusted to the maximum allowed frequency, and the working frequency of the electromagnetic induction heating module is adjusted to the minimum allowed frequency when the thermal efficiency is higher than the set threshold. When the ratio of the heat efficiency to the threshold value is less than 0.9, the central control unit increases the working frequency by 5%-10% on the basis of the current frequency, and if the heat efficiency still fails to meet the standard after adjustment, the central control unit continues to increase the working frequency by 5%-10%, until the heat efficiency meets the standard or the working frequency reaches the maximum allowable frequency, which is 1.2 times the resonant frequency of the induction coil. The scheme solves the problems of poor heat efficiency adjustment effect and potential safety hazards of the equipment by the explicit stepwise adjustment mode of the working frequency and the limitation of the maximum allowable frequency, and realizes the effective recovery of the heat efficiency and the safe operation of the equipment. It is worth mentioning that the stepwise adjustment mode of increasing the frequency by 5%-10% can ensure the gradual recovery of the heat efficiency and avoid the impact on the equipment caused by sudden change of the frequency; and the setting of the maximum allowable frequency provides a safety guarantee for the operation of the equipment and prevents the damage of the induction coil caused by excessively high frequency.

[0065] The technical effects achieved by the above embodiments include: the heat efficiency can be quickly and effectively recovered to above the set threshold value, and energy waste is reduced; the frequency adjustment process is smooth, which ensures the stable operation of the lead melting furnace; the limitation of the maximum allowable frequency protects the key components such as the induction coil, prolongs the service life of the equipment, and ensures the safety and reliability of the energy efficiency optimization process.

[0066] The above is only a preferred embodiment of the present application, and does not limit the present application in other forms. Any person skilled in the art can modify or change the above disclosed technical content to equivalent embodiments applied to other fields, but any simple modification, equivalent change and modification made according to the technical essence of the present application to the above embodiments without departing from the technical solution content of the present application still belongs to the protection scope of the technical solution of the present application.

Claims

1. A lead melting furnace control circuit system, characterized in that: include: An electromagnetic induction heating module, a temperature detection module, an insulation layer heat loss monitoring module, a power grid parameter acquisition module, a central control unit, and a human-computer interaction module. The electromagnetic induction heating module is electrically connected to the central control unit and is used to adjust the heating power of the lead melting furnace body according to the control signal output by the central control unit; The temperature detection module includes at least three temperature sensors arranged in different areas inside the furnace body, which are used to collect temperature data inside the furnace body in real time and transmit it to the central control unit; The insulation layer heat loss monitoring module includes a heat flow sensor and an insulation layer temperature sensor, which are used to collect the heat loss rate of the insulation layer and the temperature difference between the inner and outer walls of the insulation layer and transmit them to the central control unit; The grid parameter acquisition module includes a current sensor, a voltage sensor and a harmonic detector, which are used to collect the real-time current, voltage and harmonic content of the grid and transmit them to the central control unit; The central control unit communicates bidirectionally with the temperature detection module, the insulation layer heat loss monitoring module, the power grid parameter acquisition module and the human-computer interaction module respectively. It can dynamically adjust the output power, start / stop timing and operating frequency of the electromagnetic induction heating module through the built-in control algorithm according to the received temperature data, heat loss data and power grid parameters, so as to achieve efficient heating of the lead melting furnace body, uniform temperature control and power grid load protection. The human-computer interaction module is used to input parameters such as target temperature and heating time and display the working status information of the furnace body.

2. A lead melting furnace control circuit system according to claim 1, characterized in that: The electromagnetic induction heating module includes an IGBT inverter unit, a resonant capacitor group and an induction coil. The input end of the IGBT inverter unit is connected to a three-phase AC power supply, and the output end is connected in series with the resonant capacitor group and the induction coil to form a resonant circuit. The control end of the IGBT inverter unit is connected to a central control unit and can adjust the inverter frequency and output power according to the PWM signal output by the central control unit.

3. The lead melting furnace control circuit system according to claim 1, characterized in that: The temperature sensor used in the temperature detection module is a K-type thermocouple. The measurement range of the K-type thermocouple is 0-500°C, and the measurement accuracy is ±1°C. The three temperature sensors are respectively arranged at the center position of the bottom of the furnace body, the middle position of the side wall of the furnace body, and the edge position of the top of the furnace body. Each temperature sensor is connected to the A / D conversion interface of the central control unit through a shielded cable.

4. The lead melting furnace control circuit system according to claim 1, characterized in that: The central control unit adopts an STM32H743 microprocessor, which has a built-in floating-point arithmetic unit and a high-speed A / D converter, capable of realizing real-time acquisition and processing of temperature data, heat loss data and power grid parameters, and has at least 4 PWM output interfaces and 8 GPIO interfaces, which are respectively used to connect the electromagnetic induction heating module and the control end of each monitoring module.

5. The lead melting furnace control circuit system according to claim 1, characterized in that: The control algorithm built into the central control unit includes a dynamic power regulation algorithm, and the output power calculation formula of the algorithm is: ； in, is the output power of the electromagnetic induction heating module; is the proportional coefficient, ranging from 0.5 to 2.0; is the deviation between the actual furnace temperature and the target temperature, = target temperature - actual temperature; is the integral coefficient, and its value range is 0.01-0.1; is the integral value of temperature deviation within time t; is the differential coefficient, ranging from 0.1 to 1.0; dT / dt is the rate of change of furnace temperature; is the heat loss correction coefficient of the insulation layer, ranging from 0.005 to 0.02; H is the thickness of the insulation layer; The temperature difference between the inner and outer walls of the insulation layer; The maximum temperature deviation allowed for the furnace body.

6. The lead melting furnace control circuit system according to claim 1, characterized in that: The central control unit also has a built-in soft start control algorithm for controlling the startup process of the electromagnetic induction heating module. The startup current limiting formula is: ； in, is the starting current at time t; is the maximum starting current allowed by the module; β is the current rise rate adjustment coefficient, ranging from 0.8 to 1.2; t is the starting time; is the soft start time constant, ranging from 0.5 to 5 seconds; is the grid voltage correction coefficient, ranging from 0.1 to 0.3; is the real-time voltage of the power grid; is the rated voltage of the grid.

7. The lead melting furnace control circuit system according to claim 1, characterized in that: The central control unit also has a built-in energy efficiency optimization algorithm for optimizing heating efficiency in real time. The energy efficiency correction formula is: ； in, is the optimized thermal efficiency; is the basic thermal efficiency, with a value of 0.9-0.95; is the power correction coefficient, ranging from 0.05 to 0.2; P is the actual output power; is the rated power; THD is the total harmonic distortion rate of the power grid; is the maximum allowable total harmonic distortion rate; κ is the temperature change rate correction coefficient, which ranges from 0.02 to 0.1; is the furnace temperature change rate; is the maximum allowable temperature change rate.

8. A lead melting furnace control method, applied to the lead melting furnace control circuit system according to any one of claims 1 to 7, characterized in that: include S1: Input the target temperature, insulation layer thickness, and heating time parameters through the human-computer interaction module. The central control unit performs initialization testing on each module to confirm that the temperature sensor, heat flow sensor, and power grid parameter acquisition module are working properly. S2: The central control unit outputs a control signal to the electromagnetic induction heating module according to the soft start control algorithm, and controls the starting process according to the starting current limiting formula described in the starting current limiting formula, so that the starting current gradually increases from 0 to the stable working current; S3: During the heating process, the central control unit receives in real time the temperature data transmitted by the temperature detection module, the heat loss data transmitted by the insulation layer heat loss monitoring module, and the grid data transmitted by the grid parameter acquisition module. It calculates the output power through the dynamic power regulation algorithm and adjusts the PWM signal duty cycle of the electromagnetic induction heating module to maintain the furnace temperature within the target temperature ±ΔTmax range; S4: The central control unit calculates the current thermal efficiency in real time according to the energy efficiency optimization formula according to claim 7. When the thermal efficiency is lower than ηbase×0.9, the central control unit automatically adjusts the operating frequency of the electromagnetic induction heating module to make the thermal efficiency return to above ηbase×0.9; S5: When the heating time reaches the set value or the furnace temperature exceeds the target temperature + ΔTmax, the central control unit controls the electromagnetic induction heating module to gradually reduce the output power until the power is 0, completing the heating process.

9. A lead melting furnace control method according to claim 8, characterized in that: In S3, when the temperature deviation of different areas of the furnace body exceeds 5°C, the central control unit adjusts the current distribution of different sections of the induction coil to control the temperature deviation of each area of ​​the furnace body within 5°C. Among them, the current distribution ratio of the induction coil section is determined according to the inverse square relationship of the temperature deviation of each area.

10. A lead melting furnace control method according to claim 8, characterized in that: In S4, the specific method of adjusting the operating frequency of the electromagnetic induction heating module is: when the thermal efficiency is lower than ηbase×0.9, the central control unit will increase the operating frequency by 5%-10% based on the current frequency. If the thermal efficiency still does not meet the standard after adjustment, it will continue to increase by 5%-10% until the thermal efficiency meets the standard or the operating frequency reaches the maximum allowable frequency, which is 1.2 times the resonant frequency of the induction coil.

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