Energy-saving intelligent control method and system for aluminum profile smelting furnace

Abstract

The present application belongs to the technical field of smelting furnace, and discloses an energy-saving intelligent control method and system for an aluminum profile smelting furnace. The method comprises: collecting the furnace top temperature, the furnace bottom temperature, the furnace door state, the fuel gas output and the combustion air output; when the furnace door is closed, calculating a heat transfer state judgment value according to the temperature difference and the change amount of the furnace top and the furnace bottom, and in combination with the fuel gas output and the combustion air output; judging whether the furnace is in a normal heat transfer state or a heat transfer blocked state according to the heat transfer state judgment value, and controlling the fuel gas output and the combustion air output according to a first control strategy or a second control strategy, respectively, wherein the second control strategy reduces the fuel gas output and limits the combustion air output relative to the first control strategy; when the furnace door is opened, suspending the update of the heat transfer state judgment value and executing an open door compensation control. The present application can improve the accuracy of the heat transfer state judgment in the furnace, reduce invalid combustion output and furnace door disturbance misjudgment, and improve the energy-saving control stability of the smelting furnace.

Description

Technical Field

[0001] This invention belongs to the field of smelting furnace technology, specifically relating to an energy-saving intelligent control method and system for an aluminum profile smelting furnace. Background Technology

[0002] Aluminum profile smelting furnaces typically provide heat to the furnace through gas burners and a combustion air system, and exhaust flue gas through a flue gas system to meet production requirements such as aluminum melting, molten aluminum heating, and heat preservation. Current combustion control methods for aluminum profile smelting furnaces generally rely on parameters such as furnace temperature, molten aluminum temperature, gas output, combustion air output, air-fuel ratio, or furnace pressure. This is achieved by adjusting actuators such as gas valves, combustion air fans, air valves, and exhaust valves to maintain the furnace temperature and combustion state within a set range.

[0003] In actual smelting, the heat transfer state inside the furnace changes with the melting stage of the aluminum material, the surface condition of the molten aluminum, the state of the furnace covering, and the airflow state. For example, in the later stages of smelting, there may be a slag layer, oxide film layer, covering layer, or incompletely melted material layer on the surface of the molten aluminum. At this time, a higher temperature in the upper part of the furnace does not necessarily mean that heat can be effectively transferred to the molten aluminum side. If the control system still mainly relies on a single temperature feedback or fixed combustion settings for adjustment, it is easy to encounter the problem of mismatch between combustion output and the actual heat transfer state inside the furnace, resulting in local overheating, increased fuel consumption, and aggravated oxidation and burning loss on the surface of the molten aluminum.

[0004] Furthermore, aluminum profile smelting furnaces typically require opening the furnace door during operations such as charging, slag removal, or slag skimming. Opening the door causes hot flue gas to escape, cold air to enter, furnace pressure fluctuations, and short-term abnormal changes in temperature readings. These disturbances affect the combustion control system's assessment of the furnace's internal conditions, making the system prone to unreasonable adjustments during door opening or shortly after door closing, thus impacting the stability of the smelting process and energy consumption control. Therefore, improvements are needed. Summary of the Invention

[0005] In view of the above situation and to overcome the defects of the prior art, the purpose of this invention is to provide an energy-saving intelligent control method and system for aluminum profile smelting furnace, so as to at least partially solve the problems mentioned in the background art.

[0006] The technical solution adopted in this invention is as follows: The first aspect of this invention proposes an energy-saving intelligent control method for an aluminum profile smelting furnace, comprising the following steps: Collect data on the furnace top temperature, furnace bottom temperature, furnace door status, gas output, and combustion air output of the aluminum smelting furnace; When the furnace door is closed, the temperature difference between the furnace top and the furnace bottom is calculated based on the furnace top temperature and the furnace bottom temperature, and the heat transfer status judgment value is calculated based on the change in the temperature difference, the gas output and the combustion air output. The heat transfer status judgment value is compared with the preset judgment conditions to determine whether the furnace is in a normal heat transfer state or a state of blocked heat transfer. When it is determined that the furnace is in a normal heat transfer state, the gas output and combustion air output are controlled according to the first control strategy; when it is determined that the furnace is in a state of hindered heat transfer, the gas output and combustion air output are controlled according to the second control strategy, wherein the second control strategy reduces the gas output and limits the combustion air output compared to the first control strategy. When the furnace door is opened, the update of the heat transfer status judgment value is paused, and door opening compensation control is executed.

[0007] In some embodiments of the present invention, the calculation of the heat transfer state judgment value includes: The change in temperature difference is determined based on the temperature difference between the top and bottom of the furnace in the current calculation cycle and the temperature difference between the top and bottom of the furnace in the previous calculation cycle or within a preset time window. The temperature difference change is corrected based on the gas output and the combustion air output. The heat transfer state judgment value is calculated based on the temperature difference between the furnace top and bottom and the corrected temperature difference change.

[0008] In some embodiments of the present invention, the preset judgment condition includes a first judgment threshold and a second judgment threshold, wherein the second judgment threshold is greater than the first judgment threshold; When the heat transfer state judgment value is greater than the second judgment threshold and continues to reach the first set time, it is determined that the furnace is in a state of heat transfer obstruction. When the heat transfer status judgment value is less than the first judgment threshold and continues to reach the second set time, it is determined that the furnace is in a normal heat transfer state.

[0009] In some embodiments of the present invention, the first control strategy includes: The target value for gas output is determined based on the deviation between the furnace bottom temperature and the target smelting temperature, and the gas output is adjusted according to the target value. The target value for combustion air output is determined based on the target value for gas output, and the output amount of combustion air is adjusted according to the target value for combustion air output. When the furnace top temperature reaches the preset upper limit, the target value of gas output is limited from continuing to increase.

[0010] In some embodiments of the present invention, the second control strategy includes: Based on the deviation between the heat transfer state judgment value and the preset judgment condition, the gas output target value is reduced, and the gas output is adjusted according to the reduced gas output target value. The target value for combustion air output is determined based on the reduced target value for gas output, and the output amount of combustion air is adjusted according to the target value for combustion air output. During the implementation period, the increase in the output of combustion air will be limited.

[0011] In some embodiments of the present invention, the door opening compensation control includes: When the furnace door is opened, the heat transfer status judgment value obtained from the most recent calculation before the furnace door was opened is maintained; The furnace pressure is collected, and the exhaust side actuator is adjusted according to the furnace pressure to reduce the exhaust side suction intensity. When the furnace pressure is lower than the preset lower pressure limit, the increase in combustion air output is restricted; when the furnace pressure is higher than the preset upper pressure limit, the increase in gas output is restricted.

[0012] In some embodiments of the present invention, when the furnace door returns to a closed state from an open state, a door closing recovery control is executed, the door closing recovery control including: The gas output, combustion air output, and exhaust side opening are restored according to the preset rate of change. After the furnace door is closed and a preset stabilization time has elapsed, the update of the heat transfer state judgment value is resumed. Furthermore, the furnace top and bottom temperatures collected during furnace door opening are not included in the calculation of the heat transfer status judgment value after recovery.

[0013] In some embodiments of the present invention, safety limiting control is performed during the execution of the first control strategy, the second control strategy, and the door opening compensation control. The safety limiting control includes: acquiring furnace pressure, flue gas temperature, flame detection signal, and gas pressure; When the furnace pressure exceeds the preset safe pressure range, the flue gas temperature exceeds the preset upper temperature limit, the flame detection signal is abnormal, or the gas pressure is abnormal, the current control strategy is exited, and the gas output, combustion air output, and flue gas side opening are adjusted to the preset safe control state.

[0014] A second aspect of this invention provides an energy-saving intelligent control system for an aluminum profile smelting furnace, comprising: The data acquisition module is used to collect data on the furnace top temperature, furnace bottom temperature, furnace door status, gas output, and combustion air output of the aluminum smelting furnace. The heat transfer status judgment module is used to calculate the temperature difference between the furnace top and the furnace bottom based on the furnace top temperature and the furnace bottom temperature when the furnace door is closed, and to calculate the heat transfer status judgment value based on the change in the temperature difference, the gas output and the combustion air output. The status comparison module is used to compare the heat transfer status judgment value with the preset judgment conditions to determine whether the furnace is in a normal heat transfer state or a heat transfer blocked state. The combustion control module is used to control the gas output and combustion air output according to a first control strategy when it is determined that the furnace is in a normal heat transfer state, and to control the gas output and combustion air output according to a second control strategy when it is determined that the furnace is in a state of heat transfer obstruction, wherein the second control strategy reduces the gas output and limits the combustion air output compared to the first control strategy. The door opening compensation module is used to pause the updating of the heat transfer status judgment value and perform door opening compensation control when the furnace door is opened.

[0015] In some embodiments of the present invention, the system further includes a safety limiting module and an execution adjustment module; The safety limiting module is used to acquire furnace pressure, flue gas temperature, flame detection signal and gas pressure, and when at least one of the furnace pressure, flue gas temperature, flame detection signal and gas pressure meets the abnormal conditions, it adjusts the gas output, combustion air output and flue gas side opening to the preset safety control state. The execution adjustment module includes a gas adjustment unit, a combustion air adjustment unit, and a smoke exhaust adjustment unit. The gas adjustment unit is used to adjust the gas output, the combustion air adjustment unit is used to adjust the combustion air output, and the smoke exhaust adjustment unit is used to adjust the smoke exhaust side opening.

[0016] The beneficial effects achieved by this invention are as follows: This invention collects data on furnace top temperature, furnace bottom temperature, furnace door status, gas output, and combustion air output. When the furnace door is closed, it calculates a heat transfer status judgment value based on the temperature difference between the furnace top and bottom, as well as the gas and combustion air output. This allows the heat transfer status judgment to not only reflect the temperature differences within the furnace but also to make a comprehensive judgment based on changes in combustion output, thereby improving the accuracy and stability of furnace heat transfer status identification. Simultaneously, this invention distinguishes between normal heat transfer and heat transfer obstruction states based on the heat transfer status judgment value, and adjusts the gas and combustion air output using a first control strategy and a second control strategy respectively. This enables the combustion output to be matched and adjusted according to changes in the furnace heat transfer status, which helps improve the effective utilization rate of gas heat, reduces ineffective combustion output during heat transfer obstruction stages, and lowers gas consumption and the risk of localized overheating within the furnace.

[0017] This invention suspends the updating of the heat transfer status judgment value and performs door opening compensation control when the furnace door is opened. This can reduce the impact of cold air entering, hot flue gas escaping and abnormal temperature detection caused by the furnace door opening on the control judgment, thereby improving the stability and adaptability of energy-saving control of aluminum profile melting furnace. Attached Figure Description

[0018] Figure 1 This is a flowchart of an energy-saving intelligent control method for an aluminum profile melting furnace according to an embodiment of the present invention.

[0019] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Reference Figure 1 The first aspect of this invention proposes an energy-saving intelligent control method for an aluminum profile melting furnace. During the melting process, the furnace top temperature, furnace bottom temperature, furnace door status, gas output, and combustion air output are collected. The furnace top temperature reflects the thermal field status of the upper part of the furnace chamber, the furnace bottom temperature reflects the temperature response of the furnace bottom or the heated area on the aluminum molten side, the furnace door status determines whether there is a door opening disturbance, and the gas output and combustion air output reflect the current combustion output status.

[0022] When the furnace door is closed, the temperature difference between the furnace top and bottom is calculated based on the furnace top and bottom temperatures. Generally, when heat from the upper part of the furnace can be effectively transferred to the molten aluminum side, the temperature difference between the furnace top and bottom temperatures remains relatively stable. When the temperature in the upper part of the furnace rises rapidly while the temperature at the bottom responds slowly, it indicates that the effectiveness of heat transfer from the upper part of the furnace to the furnace bottom or molten aluminum side may be reduced. To reduce the bias caused by judging solely based on the temperature difference, a heat transfer state judgment value is further calculated based on the change in the temperature difference, the gas output, and the combustion air output. This heat transfer state judgment value reflects the heat transfer state inside the furnace, and its trend can characterize whether the furnace is approaching a normal heat transfer state or a state of hindered heat transfer.

[0023] The heat transfer status judgment value is compared with the preset judgment conditions to determine whether the furnace is in a normal heat transfer state or a heat transfer blocked state. A normal heat transfer state means that heat from the upper part of the furnace can be effectively transferred to the furnace bottom or the molten aluminum side, and the combustion output can be effectively used for melting aluminum or heating the molten aluminum. A heat transfer blocked state means that the temperature change between the upper part of the furnace and the furnace bottom indicates insufficient heat transfer to the furnace bottom or the molten aluminum side, and continuing to maintain a high combustion output may cause local overheating or increased ineffective energy consumption.

[0024] When the furnace is determined to be in a normal heat transfer state, the output of gas and combustion air is controlled according to the first control strategy. The first control strategy is used to match the output of gas and combustion air with the current melting and heating requirements, so as to maintain the effective heating state required for aluminum melting or molten aluminum heating.

[0025] When it is determined that the furnace is in a state of impeded heat transfer, the output of gas and combustion air is controlled according to the second control strategy. The second control strategy reduces the output of gas and limits the output of combustion air compared to the first control strategy, thereby reducing ineffective high-intensity combustion during the heat transfer impeded stage and reducing the tendency for local overheating in the furnace.

[0026] When the furnace door is opened, the update of the heat transfer status judgment value is paused, and door opening compensation control is implemented. Because opening the furnace door causes cold air to enter, hot flue gas to escape, and short-term fluctuations in the furnace temperature detection value, continuing to update the heat transfer status judgment value during this stage could easily misinterpret the door opening disturbance as a change in the actual heat transfer status inside the furnace. Therefore, updating the heat transfer status judgment value is paused during furnace door opening to reduce the impact of transient disturbances on combustion control judgment; simultaneously, door opening compensation control is implemented to minimize the impact of furnace door opening on the combustion status and temperature detection results inside the furnace.

[0027] The above-mentioned data acquisition, calculation, comparison, and control steps can be implemented by a PLC, industrial controller, or other device with data processing and execution control functions that is matched with the aluminum profile melting furnace.

[0028] In some embodiments, the heat transfer state judgment value can be calculated in the following manner.

[0029] Within each calculation cycle, the temperature difference between the furnace top and bottom is calculated based on the collected furnace top and bottom temperatures. For ease of explanation, let the current calculation cycle be the nth calculation cycle, the furnace top temperature be T_top(n), and the furnace bottom temperature be T_bottom(n). Then, the temperature difference ΔT(n) between the furnace top and bottom can be expressed as: ΔT(n)=T_top(n)-T_bottom(n).

[0030] Where T_top(n) represents the furnace top temperature collected in the nth calculation cycle, and T_bottom(n) represents the furnace bottom temperature collected in the nth calculation cycle. The larger ΔT(n) is, the more significant the temperature difference between the upper thermal field of the furnace and the furnace bottom or the heated area on the aluminum molten side is.

[0031] Furthermore, the temperature difference change is determined based on the temperature difference between the furnace top and bottom in the current calculation cycle and the temperature difference between the furnace top and bottom in the previous calculation cycle or within a preset time window. For example, the temperature difference change ΔT_v(n) can be calculated based on the temperature difference ΔT(n) in the current calculation cycle and the temperature difference ΔT(n-1) in the previous calculation cycle, and its expression can be: ΔT_v(n)=ΔT(n)-ΔT(n-1).

[0032] In another example, the temperature difference at intervals of m sampling periods can also be selected for calculation to reduce the impact of single-point fluctuations. In this case, the rate of change of temperature difference K_T(n) can be expressed as: K_T(n)=[ΔT(n)-ΔT(nm)] / (m×T_s).

[0033] Where T_s is the sampling period and m is the differential step size. m can be set according to the furnace volume, thermal inertia, response speed of the temperature detection element, and control cycle, for example, it can be 2 to 20. The temperature difference change rate K_T(n) is used to reflect the rate at which the temperature difference between the furnace top and bottom increases over time.

[0034] Since the temperature difference between the furnace top and bottom is not only related to the heat transfer state inside the furnace, but may also be affected by changes in the gas output and combustion air output, the temperature difference change can be corrected based on the gas output and combustion air output. For example, the equivalent combustion input Q_in(n) can be determined first based on the gas output and combustion air output. For instance, Q_in(n) can be obtained by weighting the gas output G(n) and the combustion air output A(n): Q_in(n) = p × G(n) + q × A(n).

[0035] Wherein, G(n) is the gas output in the nth calculation cycle, A(n) is the combustion air output in the nth calculation cycle, and p and q are calibration coefficients. The gas output G(n) can be the gas valve opening, the gas flow setpoint, or the burner load percentage; the combustion air output A(n) can be the combustion air fan frequency, the combustion air valve opening, or the combustion air flow setpoint.

[0036] Further calculation of the change in equivalent combustion input ΔQ_in(n) can be performed, and its expression can be: ΔQ_in(n)=Q_in(n)-Q_in(n-1).

[0037] When the output of fuel gas and combustion air increases, the furnace top temperature may rise rapidly due to the increased combustion output. In this case, the widening temperature difference between the furnace top and bottom does not necessarily indicate impeded heat transfer. Therefore, ΔQ_in(n) can be used to correct for the change in temperature difference or the rate of change in temperature difference. As an example, the corrected change in temperature difference K_c(n) can be expressed as: K_c(n)=K_T(n)-r×ΔQ_in(n).

[0038] Where r is the correction coefficient. Through the above correction, when the temperature difference change is mainly caused by the increase in gas output and combustion air output, the influence of this change on the heat transfer status judgment value can be reduced; when the gas output and combustion air output change is small, but the temperature difference between the furnace top and the furnace bottom continues to expand, the corrected temperature difference change remains at a high level to reflect the trend of heat transfer obstruction in the furnace.

[0039] After obtaining the temperature difference between the furnace top and bottom, as well as the corrected temperature difference change, the heat transfer state judgment value I(n) can be calculated. For example, the heat transfer state judgment value I(n) can be expressed as: I(n) = a × ΔT(n) + b × K_c(n).

[0040] Where a and b are weighting coefficients. a is used to characterize the influence of the temperature difference between the furnace top and the furnace bottom on the heat transfer status judgment value, and b is used to characterize the influence of the corrected temperature difference change on the heat transfer status judgment value.

[0041] In another example, the changes in the equivalent combustion input corresponding to the gas output and combustion air output can also be directly incorporated into the calculation of the heat transfer state judgment value. For example, the heat transfer state judgment value I(n) can be expressed as: I(n)=a×ΔT(n)+b×K_T(n)-c×ΔQ_in(n).

[0042] Where c is the combustion input correction coefficient. This formula means that when the temperature difference between the furnace top and bottom is large and the rate of temperature change is high, the heat transfer status judgment value increases; when the temperature difference change is mainly caused by the increase in gas output and combustion air output, the judgment value is corrected by -c×ΔQ_in(n) to reduce misjudgments caused by changes in combustion output.

[0043] Optionally, the furnace bottom temperature response can also be introduced as a verification parameter. For example, the furnace bottom temperature response H(n) can be expressed as: H(n)=[T_bottom(n)-T_bottom(nm)] / [(m×T_s)×(Q_in(n)+ε)].

[0044] Where ε is a constant to prevent the denominator from being zero. When the equivalent combustion input is high and the furnace bottom temperature response H(n) is low, and the temperature difference between the furnace top and bottom and the rate of change of the temperature difference are high, the reliability of the judgment of heat transfer obstruction can be improved.

[0045] In the above formulas, a, b, c, p, q, r, m, T_s, and ε can all be calibrated based on the furnace type, furnace volume, burner arrangement, temperature detection location, gas type, combustion air system response characteristics, and on-site smelting process of the aluminum profile melting furnace. The above formulas are merely exemplary calculation methods for the heat transfer state judgment value and do not limit the use of a single calculation formula. In practical applications, any judgment value for determining the heat transfer state within the furnace that can be calculated based on the temperature difference between the furnace top and bottom, the amount of temperature difference change, and the influence of gas output and combustion air output on the temperature difference change can be used as the calculation method for the heat transfer state judgment value.

[0046] In some embodiments, the preset judgment condition includes a first judgment threshold and a second judgment threshold, wherein the second judgment threshold is greater than the first judgment threshold. For ease of explanation, the first judgment threshold can be denoted as I1, and the second judgment threshold can be denoted as I2, and I2 > I1. The first judgment threshold I1 is used to determine whether the heat transfer state inside the furnace has recovered to a relatively normal state, and the second judgment threshold I2 is used to determine whether the furnace has entered a state of hindered heat transfer.

[0047] During the smelting process, the calculated heat transfer state judgment value I(n) is compared with the first judgment threshold I1 and the second judgment threshold I2. When the heat transfer state judgment value I(n) is greater than the second judgment threshold I2, and this state continues for a first set time t1, the furnace is judged to be in a state of hindered heat transfer. The use of duration-based judgment here is to avoid misjudgments caused by transient factors such as flame fluctuations, short-term feeding, and temperature detection noise. For example, if the heat transfer state judgment value briefly exceeds the second judgment threshold I2 but does not continue for the first set time t1, the furnace may not be switched to a state of hindered heat transfer.

[0048] When the heat transfer status judgment value I(n) is less than the first judgment threshold I1, and this state continues for a second set time t2, the furnace is judged to be in a normal heat transfer state. This judgment indicates that the temperature difference between the furnace top and bottom and its changing trend have fallen back to a lower level, and the heat transfer from the upper part of the furnace to the furnace bottom or the molten aluminum side is tending to recover. By setting the second set time t2, the control strategy can be avoided from switching immediately when the heat transfer status judgment value drops for a short time, thereby improving the stability of the status judgment.

[0049] When the heat transfer state judgment value I(n) is between the first judgment threshold I1 and the second judgment threshold I2, the current heat transfer state judgment result can remain unchanged. For example, if it has been previously judged that the furnace is in a normal heat transfer state, then the normal heat transfer state will remain until the heat transfer state judgment value continuously exceeds the second judgment threshold I2; if it has been previously judged that the furnace is in a heat transfer blocked state, then the blocked heat transfer state will remain until the heat transfer state judgment value continuously falls below the first judgment threshold I1. Through the hysteresis interval formed by the first judgment threshold I1 and the second judgment threshold I2, the frequent switching between the normal state and the blocked state of heat transfer can be reduced.

[0050] For example, the first set time t1 and the second set time t2 can be set according to the furnace type, furnace volume, response speed of the temperature detection element, adjustment speed of the combustion system, and the stage of aluminum melting. For example, t1 and t2 can be set to 30 to 300 seconds. The first judgment threshold I1 and the second judgment threshold I2 can be determined by trial operation data, historical smelting data, or on-site calibration. The above values ​​are only examples and do not limit the specific values ​​of the first judgment threshold, the second judgment threshold, the first set time, and the second set time.

[0051] In some embodiments, when it is determined that the furnace is in a normal heat transfer state, a first control strategy is executed. The first control strategy is mainly used to match the output of gas and combustion air with the melting or heating requirements of aluminum material or molten aluminum when the heat transfer in the furnace is relatively smooth, so as to improve the effectiveness of transferring combustion heat to the furnace bottom or molten aluminum side.

[0052] Specifically, the target gas output value can be determined based on the deviation between the furnace bottom temperature and the target smelting temperature. For ease of explanation, let the furnace bottom temperature be T_bottom and the target smelting temperature be T_set. Then, the furnace bottom temperature deviation E_T can be expressed as: E_T = T_set - T_bottom.

[0053] When E_T is large, it indicates that the furnace bottom temperature is far from the target melting temperature, requiring a higher combustion output to meet the heating demand; when E_T gradually decreases, it indicates that the furnace bottom temperature is approaching the target melting temperature, and the increase in the target gas output value can be reduced accordingly. For example, the target gas output value G_set can be determined based on the furnace bottom temperature deviation E_T, for example: G_set = G_base + k_g × E_T.

[0054] wherein, G_base is a basic gas output value, and k_g is a gas regulation coefficient. In practical applications, G_set can also be subjected to amplitude limiting processing according to the smelting stage, furnace type, charging amount, opening range of the gas valve and the rated capacity of the burner, so that it does not exceed the allowable upper limit of gas output and is not lower than the lower limit of gas output required for maintaining stable combustion.

[0055] After determining the gas output target value G_set, the combustion-supporting air output target value can be determined according to the gas output target value. By way of example, the combustion-supporting air output target value A_set may be determined according to a preset combustion cooperation relationship, for example: A_set=k_a×G_set.

[0056] wherein, k_a is a combustion-supporting air cooperation coefficient corresponding to the gas output target value. The combustion-supporting air cooperation coefficient can be calibrated according to gas type, burner structure, target air-fuel ratio and on-site combustion stability requirements. By enabling the combustion-supporting air output target value to change synchronously with the gas output target value, a relatively stable cooperation relationship between the gas output amount and the combustion-supporting air output amount can be maintained, and insufficient combustion or excessive excess air caused by mismatching between the gas output amount and the combustion-supporting air output amount can be avoided.

[0057] When the first control strategy is executed, the gas output target value can also be constrained according to the furnace top temperature. For convenience of description, the furnace top temperature is recorded as T_top, and the upper limit of the furnace top temperature is T_top,max. When T_top does not meet the furnace top temperature upper limit condition, the gas output amount is adjusted according to the gas output target value determined by the furnace bottom temperature deviation; when T_top meets the preset upper limit condition, the gas output target value is restricted from continuing to increase. For example, the corrected gas output target value G_set' can be determined according to the following rules: When T_top<T_top,max, G_set'=G_set; When T_top≥T_top,max, G_set' no longer continues to increase with the increase of the furnace bottom temperature deviation.

[0058] In another example, when T_top meets the preset upper limit condition, the gas output target value can also be limited to the smaller value between the current gas output target value and the preset upper limit value, so as to avoid local overheating caused by continuous temperature rise of the upper part of the furnace hearth. This can be expressed as: G_set'=min(G_set,G_limit).

[0059] wherein, G_limit is an allowable gas output limit value when the furnace top temperature meets the preset upper limit condition.

[0060] Through the aforementioned first control strategy, when heat transfer within the furnace is normal, the gas output is mainly adjusted based on the deviation between the furnace bottom temperature and the target smelting temperature. The combustion air output is adjusted in match with the target gas output value, while the furnace top temperature is used to impose an upper limit constraint on the target gas output value. This not only satisfies the effective heating required for aluminum melting or molten aluminum heating but also reduces the risk of localized overheating caused by excessively high temperatures in the upper part of the furnace.

[0061] In some embodiments, when it is determined that the furnace is in a state of impeded heat transfer, a second control strategy is executed. The second control strategy is used to reduce the output of ineffective high-intensity combustion and limit the continued increase of combustion air output when the efficiency of heat transfer from the upper part of the furnace to the bottom of the furnace or the molten aluminum side decreases, so as to reduce the tendency of local overheating and oxidation in the furnace.

[0062] Specifically, the target gas output value can be reduced based on the deviation between the heat transfer state judgment value and the heat transfer obstruction judgment threshold. For ease of explanation, let the heat transfer state judgment value be I, and the heat transfer obstruction judgment threshold be I2. Then, the heat transfer obstruction deviation E_R can be expressed as: E_R = I - I2.

[0063] When E_R is greater than 0, it indicates that the heat transfer status judgment value has exceeded the heat transfer obstruction judgment threshold, and the larger E_R is, the more obvious the degree of heat transfer obstruction. In this case, the gas output target value determined under the first control strategy can be lowered based on E_R. For example, if the gas output target value determined under the first control strategy is G_set, then the gas output target value G_low under the second control strategy can be expressed as: G_low = G_set - k_r × E_R.

[0064] Where k_r is the gas output reduction coefficient. In this way, the greater the deviation of heat transfer obstruction, the greater the reduction in the target value of gas output, thereby reducing the ineffective energy consumption caused by continuing to maintain a high combustion output during the heat transfer obstruction stage.

[0065] To ensure combustion stability, a lower limit can be set for reducing the target gas output value. For example, the reduced target gas output value can be limited to: G_low=max(G_min,G_set-k_r×E_R).

[0066] G_min represents the lower limit of gas output required to maintain stable combustion. By setting G_min, it is possible to prevent the gas output from being excessively reduced, which could affect flame stability.

[0067] After determining the reduced target value of gas output G_low, the target value of combustion air output A_low can be determined based on G_low. For example, A_low can be determined according to a preset combustion coordination relationship: A_low = k_b × G_low.

[0068] Wherein, k_b is the combustion air matching coefficient under the second control strategy. k_b can be calibrated according to the gas type, burner structure, furnace oxidation control requirements, and flame stability requirements. Compared with the first control strategy, the target value of combustion air output under the second control strategy is adjusted according to the reduced target value of gas output, thereby avoiding the combustion air output from remaining at a high level after the gas output is reduced.

[0069] During the execution of the second control strategy, the increase in the combustion air output is also limited. For example, a maximum single-cycle increase ΔA_max in the combustion air output can be set such that the target value A_set(n) of the combustion air output for the current calculation cycle satisfies: A_set(n)≤A_set(n-1)+ΔA_max.

[0070] Where A_set(n-1) is the target value of combustion air output in the previous calculation cycle, and ΔA_max is the preset limit value for the increase in combustion air output. This limit can prevent the combustion air output from increasing rapidly under the condition of impeded heat transfer, thereby reducing the risk of a sudden increase in the oxidizing atmosphere inside the furnace.

[0071] In another example, the upper limit of the combustion air output can also be limited based on the heat transfer resistance deviation E_R. For example, the upper limit of the combustion air output A_limit can be expressed as: A_limit = A_base - k_a2 × E_R.

[0072] Where A_base is the upper limit of the basic combustion air output, and k_a2 is the combustion air limiting coefficient. When the heat transfer resistance deviation E_R increases, the upper limit of the combustion air output decreases accordingly. In this case, the target value of the combustion air output A_set can be the smaller value between the calculated value based on the preset combustion coordination relationship and A_limit. A_set=min(k_b×G_low,A_limit).

[0073] Through the aforementioned second control strategy, under the condition of impeded heat transfer, the target value of gas output is lowered according to the degree of heat transfer obstruction, and the target value of combustion air output is adjusted accordingly to match the lowered target value of gas output, while limiting the increase in the amount of combustion air output. This reduces ineffective combustion output during the heat transfer obstruction stage, lowers the risk of overheating in the upper part of the furnace or the surface area of ​​the molten aluminum, and reduces the oxidation tendency caused by excessive increase in combustion air.

[0074] In some embodiments, door opening compensation control is performed when the furnace door is opened. The door opening compensation control is used to reduce the impact of cold air entering, hot flue gas escaping, and furnace pressure fluctuations on heat transfer status judgment and combustion control during furnace door opening.

[0075] Specifically, when the furnace door is opened, the heat transfer state judgment value most recently calculated before the door is opened is retained. For ease of explanation, the most recently valid heat transfer state judgment value before the furnace door is opened is denoted as I_hold. After the furnace door is opened, the heat transfer state judgment value is no longer updated based on the furnace top and furnace bottom temperatures collected during the door opening period; instead, the heat transfer state judgment value is retained as follows: I(n) = I_hold.

[0076] Wherein, I(n) is the heat transfer status judgment value corresponding to the nth calculation cycle during the furnace door opening period. This method can avoid the misuse of short-term temperature fluctuations caused by furnace door opening to judge the true heat transfer status inside the furnace.

[0077] When performing door opening compensation control, the furnace pressure can also be collected, and the exhaust-side actuator can be adjusted according to the furnace pressure to reduce the exhaust-side suction intensity. The exhaust-side actuator may include one or more of an exhaust valve, a flue damper, and an induced draft fan. For example, let the furnace pressure be P_f and the door opening compensation pressure target value be P_door. When the furnace door is opened, the opening degree of the exhaust valve can be reduced or the frequency of the induced draft fan can be reduced to make the furnace pressure approach the door opening compensation pressure target value P_door.

[0078] For example, the smoke exhaust side opening S_exh can be adjusted as follows: S_exh(n)=S_exh(n-1)-k_p×(P_door-P_f).

[0079] Where S_exh(n) is the flue gas side opening degree in the current calculation cycle, S_exh(n-1) is the flue gas side opening degree in the previous calculation cycle, and k_p is the flue gas adjustment coefficient. When the furnace pressure P_f is lower than the door opening compensation pressure target value P_door, the flue gas side opening degree is reduced to reduce the flue gas side suction intensity, thereby reducing the tendency for outside cold air to be drawn into the furnace during the furnace door opening period.

[0080] In one example, after the furnace door is opened, the exhaust side opening can also be reduced by a preset percentage based on the opening percentage. For example, if the exhaust side opening before the furnace door is opened is denoted as S_exh0, and the exhaust side opening during the door opening compensation period is denoted as S_exh_door, it can be set as follows: S_exh_door=S_exh0×(1-λ).

[0081] Wherein, λ is the exhaust side downdraft extraction ratio, which can be set according to the furnace door area, exhaust capacity, and furnace pressure fluctuations, for example, it can be 20% to 60%. The above values ​​are only examples and do not limit the specific range of the exhaust side downdraft extraction ratio.

[0082] In door opening compensation control, a safety boundary can also be set based on the furnace pressure. When the furnace pressure is lower than the preset lower pressure limit, it indicates that there may be a negative pressure suction trend inside the furnace. At this time, the increase in the combustion air output is limited to reduce the impact of the increased combustion air on the airflow disturbance inside the furnace. For example, let the preset lower pressure limit be P_min. When P_f < P_min, the target value A_set of the combustion air output can be made to satisfy: A_set(n)≤A_set(n-1).

[0083] Where A_set(n) is the target value of combustion air output for the current calculation cycle, and A_set(n-1) is the target value of combustion air output for the previous calculation cycle. This restriction prevents the combustion air output from continuing to increase when the furnace door is open and the furnace pressure is low.

[0084] When the furnace pressure exceeds the preset pressure limit, it indicates that the furnace pressure is too high, which may pose a risk of excessive hot flue gas escape or on-site safety. In this case, the increase in gas output should be limited. For example, let the preset pressure limit be P_max. When P_f > P_max, the target gas output value G_set can be satisfied as follows: G_set(n)≤G_set(n-1).

[0085] Wherein, G_set(n) is the target value of gas output for the current calculation cycle, and G_set(n-1) is the target value of gas output for the previous calculation cycle. This limitation can prevent the furnace pressure from further increasing due to the continued increase in gas output during furnace door opening.

[0086] In one example, the door opening compensation control can be activated immediately after the furnace door opening signal appears, or it can be activated in advance after receiving the furnace door drive signal, hydraulic cylinder action signal, feeder linkage signal, or slag remover linkage signal. By activating the door opening compensation control in advance, the suction intensity on the exhaust side can be reduced before the furnace door is fully opened, thereby reducing the pressure fluctuation at the moment the furnace door opens.

[0087] Through the aforementioned door opening compensation control, during the furnace door opening period, the heat transfer status judgment value remains at the effective value before opening, the exhaust side suction intensity is adjusted according to the furnace pressure, and the increase in combustion air output or gas output is limited according to the upper and lower pressure limits. This reduces the impact of door opening disturbances on the heat transfer status judgment value and improves the stability of combustion control during door opening operations such as feeding, slag removal, or slag retrieval.

[0088] In some embodiments, when the furnace door returns to a closed state from an open state, a door-closing recovery control is executed. The door-closing recovery control is used to gradually restore the gas output, combustion air output, and flue gas side opening that were adjusted during the furnace door opening, and to resume updating the heat transfer status judgment value after the airflow and temperature detection values ​​in the furnace have stabilized.

[0089] Specifically, when the furnace door is detected to have changed from open to closed, the gas output, combustion air output, and exhaust side opening are restored according to a preset rate of change. Since the furnace pressure, flue gas flow, and temperature may still fluctuate briefly after the furnace door is closed, immediately restoring the gas output, combustion air output, and exhaust side opening to the closed-door control state could easily cause furnace pressure fluctuations or sudden changes in combustion output. Therefore, a ramp-up recovery method can be used to gradually return the above-mentioned parameters to the corresponding closed-door control targets.

[0090] For example, if the target gas output value after the furnace door is closed is G_set_close, the current target gas output value is G_set(n), and the rate of change of the target gas output recovery is R_G, then the target gas output value can be recovered in the following way: G_set(n)=G_set(n-1)+R_G×T_s.

[0091] Where G_set(n-1) is the target value of gas output in the previous calculation cycle, and T_s is the sampling period. Once G_set(n) reaches G_set_close, it remains at G_set_close. This method avoids sudden changes in gas output after the furnace door is closed.

[0092] Similarly, the target value of the combustion air output can also be recovered according to a preset rate of change. For example, if the target value of the combustion air output after the furnace door is closed is A_set_close, the current target value of the combustion air output is A_set(n), and the rate of change for the recovery of the combustion air output target is R_A, then the target value of the combustion air output can be recovered as follows: A_set(n)=A_set(n-1)+R_A×T_s.

[0093] Once A_set(n) reaches A_set_close, it remains at A_set_close. By smoothly restoring the combustion air output, the impact of sudden increases in combustion air on furnace pressure and flame stability can be reduced.

[0094] The exhaust side opening can also be restored according to a preset rate of change. For example, if the target value of the exhaust side opening after the furnace door is closed is S_exh_close, the current exhaust side opening is S_exh(n), and the rate of change for restoring the exhaust side opening is R_S, then the exhaust side opening can be restored as follows: S_exh(n)=S_exh(n-1)+R_S×T_s.

[0095] Once S_exh(n) reaches S_exh_close, it remains at S_exh_close. By gradually restoring the flue gas side opening, a rapid drop in furnace pressure caused by a sudden increase in flue gas suction when the furnace door is just closed can be avoided.

[0096] When performing door-closing recovery control, the heat transfer status judgment value is updated only after a preset stabilization time has elapsed after the furnace door is closed. For example, if the furnace door closing time is t_close and the preset stabilization time is t_delay, then during the period t < t_close + t_delay, the valid heat transfer status judgment value before the furnace door was opened or during the door-closing recovery phase is maintained, and the furnace top and bottom temperatures collected during this period are not used to recalculate the heat transfer status judgment value; when t ≥ t_close + t_delay, the normal update of the heat transfer status judgment value is resumed.

[0097] For example, the preset stabilization time t_delay can be set according to the furnace volume, furnace door area, flue gas exhaust capacity, temperature detection element response speed, and on-site air conditions. As an example, t_delay can be set to 10–120 seconds. The above values ​​are only examples and do not limit the specific value of the preset stabilization time.

[0098] Furthermore, the furnace top and bottom temperatures collected during furnace door opening are not included in the calculation of the recovered heat transfer status judgment value. For example, if the heat transfer status judgment value needs to be calculated based on temperature data within a preset time window, the furnace top and bottom temperatures collected during furnace door opening can be marked as invalid data or removed from the time window used to calculate the temperature difference change. This avoids the continued impact of cold air entering, hot flue gas escaping, and abnormal temperature detection during door opening on the heat transfer status judgment value after door closure.

[0099] Through the aforementioned door-closing recovery control, after the furnace door is closed, the gas output, combustion air output, and flue gas side opening gradually recover according to a preset rate of change. The heat transfer status judgment value is updated only after a preset stabilization time, and the temperature data collected during the furnace door opening period is not included in the post-recovery calculation. This improves the continuity and stability of combustion control before and after furnace door opening and closing, and reduces the impact of door opening disturbances on subsequent heat transfer status judgments.

[0100] In some embodiments, safety limiting control is performed during the execution of the first control strategy, the second control strategy, and the door opening compensation control. The safety limiting control is used to limit or switch the gas output, combustion air output, and exhaust side opening when abnormalities occur in the furnace pressure, flue gas temperature, flame detection signal, or gas pressure, in order to ensure the safe operation of the aluminum profile smelting furnace.

[0101] Specifically, furnace pressure, flue gas temperature, flame detection signal, and gas pressure can be acquired. Furnace pressure reflects the pressure state inside the furnace, flue gas temperature reflects the heat load state on the flue gas discharge side, flame detection signal is used to determine whether burner combustion is stable, and gas pressure is used to determine whether the gas supply meets the requirements for safe combustion.

[0102] In one example, let the furnace pressure be P_f, and the preset safe pressure range be [P_safe,min, P_safe,max]. When P_f < P_safe,min, it indicates that the furnace pressure is too low, and there may be a negative pressure suction tendency in the furnace. At this time, the suction intensity on the exhaust side can be reduced, and the increase in combustion air output can be limited. When P_f > P_safe,max, it indicates that the furnace pressure is too high, and there may be excessive hot flue gas escape or on-site safety risks. At this time, the further increase in gas output can be limited, and the exhaust side opening can be appropriately increased to bring the furnace pressure back to the preset safe pressure range.

[0103] In one example, let the flue gas temperature be T_exh, and the preset upper limit be T_exh,max. When T_exh > T_exh,max, it indicates that the flue gas temperature exceeds the allowable range. At this point, the gas output can be reduced, or the target gas output value can be limited to prevent the flue gas temperature from continuing to rise. This method can reduce the risk of overheating in the flue gas system and improve the safety of continuous operation of the smelting furnace.

[0104] In one example, the flame detection signal can be provided by a flame detector, burner controller, or combustion safety interlock device. When the flame detection signal is abnormal, such as no flame is detected, the flame signal is below the set intensity, or the flame signal fluctuates continuously, the current control strategy is exited, and the gas output, combustion air output, and exhaust side opening are adjusted to a preset safety control state. The preset safety control state may include shutting down or reducing the gas output, maintaining necessary combustion air purging, and adjusting the exhaust side opening to a safe exhaust position.

[0105] In one example, the gas pressure is denoted as P_g, and the preset gas pressure range is [P_g,min, P_g,max]. When P_g is lower than the preset lower limit of gas pressure P_g,min, it indicates insufficient gas supply, which may lead to flame instability; when P_g is higher than the preset upper limit of gas pressure P_g,max, it indicates that the gas supply pressure is too high, which may affect combustion safety. At this time, the current control strategy is exited, and the gas output, combustion air output, and exhaust side opening are adjusted to the preset safety control state.

[0106] In one example, the preset safety control state can vary depending on the type of anomaly. When the furnace pressure is too low, the preset safety control state may include reducing the suction intensity on the flue gas side and limiting the increase in combustion air output; when the furnace pressure is too high, the preset safety control state may include limiting the increase in gas output and increasing the flue gas side opening; when the flue gas temperature exceeds the preset upper temperature limit, the preset safety control state may include reducing the gas output; when the flame detection signal or gas pressure is abnormal, the preset safety control state may include exiting automatic energy-saving control and switching to combustion safety interlock control.

[0107] In one example, safety limiting control may also include limiting the rate of change of gas output, combustion air output, and exhaust side opening. For example, the changes in the target gas output value G_set, the target combustion air output value A_set, and the exhaust side opening S_exh between adjacent calculation cycles can respectively satisfy: |G_set(n)-G_set(n-1)|≤ΔG_max; |A_set(n)-A_set(n-1)|≤ΔA_max; |S_exh(n)-S_exh(n-1)|≤ΔS_max.

[0108] Wherein, ΔG_max is the maximum change in the target value of gas output in a single cycle, ΔA_max is the maximum change in the target value of combustion air output in a single cycle, and ΔS_max is the maximum change in the exhaust side opening in a single cycle. By limiting the rate of change of the executed quantities, abrupt changes in combustion output and furnace pressure can be reduced, thereby improving the stability of the combustion control process.

[0109] Through the above-mentioned safety limiting control, during the execution of the first control strategy, the second control strategy, and the door opening compensation control, the current control strategy can be limited or exited in a timely manner according to the furnace pressure, flue gas temperature, flame detection signal, and gas pressure, so that the gas output, combustion air output, and flue gas side opening are kept within a safe range, thereby improving the safety and reliability of the energy-saving intelligent control process of the aluminum profile melting furnace.

[0110] In a specific example, the first control strategy, the second control strategy, and the door opening compensation control can be set according to the following parameters. It should be noted that the following parameters are only exemplary control parameters applicable to a certain aluminum profile melting furnace. In actual applications, they can be calibrated and adjusted according to the furnace type, furnace volume, burner arrangement, gas type, flue gas capacity, furnace door area, workshop ventilation conditions, and safety interlock requirements.

[0111] When the furnace door is closed and the heat transfer condition judgment value meets the normal heat transfer conditions, the first control strategy is executed. At this time, the gas output can be controlled within 70% to 100% of the rated output, and the combustion air output is adjusted synchronously according to the gas output to maintain the excess air coefficient within the range of 1.01 to 1.08. Simultaneously, the furnace pressure can be controlled within the range of +3 Pa to +10 Pa, and the exhaust-side actuators are kept in normal exhaust mode. This control method maintains a high effective heating capacity when heat transfer within the furnace is relatively smooth, thereby improving the aluminum melting efficiency and gas heat utilization rate.

[0112] When the furnace door is closed and the heat transfer status judgment value meets the heat transfer obstruction condition, the second control strategy is executed. At this time, the gas output can be reduced to 60%–90% of the pre-switch output, and the increase in combustion air output can be limited, keeping the excess air coefficient within the range of 0.95–1.02, or within the low-oxygen safety range close to the theoretical ratio. Simultaneously, the furnace pressure can be controlled within the range of +5Pa–+15Pa, and excessive suction on the exhaust side can be avoided through exhaust valves, flue dampers, or induced draft fans. This control method reduces the ineffective energy consumption caused by maintaining high combustion output during the heat transfer obstruction stage, reduces the risk of overheating in the upper part of the furnace or the aluminum molten surface area, and reduces the tendency for an increasing oxidizing atmosphere.

[0113] When the furnace door is opened or a furnace door opening signal is received, door opening compensation control is executed. At this time, the update of the heat transfer status judgment value is suspended, and the effective heat transfer status judgment value calculated most recently before the furnace door is opened is maintained; the gas output and combustion air output are constrained by the furnace pressure and safety limits, and are not used as the main temperature rise control targets; the furnace pressure target value can be increased to the range of +12Pa to +25Pa, and is lower than the preset escape safety upper limit; the flue gas side opening can be reduced by 20% to 60% based on the opening of the furnace door, or the induced draft fan frequency can be reduced to reduce the exhaust side suction intensity. Through this control method, the impact of cold air backflow, hot flue gas escape, and abnormal temperature detection values ​​on the heat transfer status judgment during furnace door opening can be reduced.

[0114] The aforementioned first control strategy, second control strategy, and door opening compensation control are not independent fixed programs, but are switched according to the furnace door status, heat transfer status judgment value, furnace pressure, and safety limit conditions. When the furnace door returns from the open state to the closed state, the gas output, combustion air output, and flue gas side opening can be restored according to a preset change rate, and the heat transfer status judgment value will be updated after a preset stabilization time.

[0115] A second aspect of this invention provides an energy-saving intelligent control system for an aluminum profile melting furnace. This system can be used to execute the aforementioned energy-saving intelligent control method for the aluminum profile melting furnace. The system includes a data acquisition module, a heat transfer status judgment module, a status comparison module, a combustion control module, and a door opening compensation module.

[0116] The data acquisition module is used to collect data on the furnace top temperature, furnace bottom temperature, furnace door status, gas output, and combustion air output of the aluminum profile melting furnace. Specifically, the furnace top temperature can be collected by thermocouples, resistance thermometers, or other temperature sensing elements located in the upper part of the furnace chamber; the furnace bottom temperature can be collected by temperature sensing elements located in the furnace bottom, lower part of the furnace wall, or near the heated area on the aluminum molten metal side; the furnace door status can be determined by furnace door limit switches, proximity switches, stroke detection devices, or furnace door drive signals; the gas output can be represented by the gas valve opening degree, gas flow rate setpoint, or burner load percentage; and the combustion air output can be represented by the combustion air fan frequency, combustion air valve opening degree, or combustion air flow rate setpoint.

[0117] The heat transfer state judgment module is used to calculate the temperature difference between the furnace top and the furnace bottom based on the furnace top temperature and the furnace bottom temperature when the furnace door is closed, and to calculate the heat transfer state judgment value based on the change in temperature difference, the gas output, and the combustion air output. Specifically, the heat transfer state judgment module can calculate the heat transfer state judgment value for judging the heat transfer state inside the furnace according to the calculation method in the aforementioned embodiments, based on the temperature difference between the furnace top and the furnace bottom, the change in temperature difference, and the influence of the gas output and the combustion air output on the temperature difference change.

[0118] The state comparison module is used to compare the heat transfer state judgment value with preset judgment conditions to determine whether the furnace is in a normal heat transfer state or a heat transfer blocked state. For example, the state comparison module can compare the heat transfer state judgment value with a first judgment threshold and a second judgment threshold, and combine the duration judgment result to output a normal heat transfer state signal or a heat transfer blocked state signal.

[0119] The combustion control module controls the gas output and combustion air output based on the judgment result output by the state comparison module. When the furnace is judged to be in a normal heat transfer state, the combustion control module controls the gas output and combustion air output according to the first control strategy to match the combustion output with the furnace bottom temperature rise requirement. When the furnace is judged to be in a state of hindered heat transfer, the combustion control module controls the gas output and combustion air output according to the second control strategy. The second control strategy reduces the gas output and limits the combustion air output compared to the first control strategy to reduce ineffective combustion output and local overheating tendency under the state of hindered heat transfer.

[0120] The door opening compensation module is used to pause the updating of the heat transfer status judgment value and perform door opening compensation control when the furnace door is opened. Specifically, when the data acquisition module acquires the furnace door opening status or receives a furnace door opening signal, the door opening compensation module can maintain the most recently calculated heat transfer status judgment value before the furnace door is opened, and prevent the temperature data acquired during the door opening from participating in the updating of the heat transfer status judgment value. At the same time, the door opening compensation module can adjust the exhaust side actuator according to the furnace pressure to reduce the exhaust side suction intensity and reduce the disturbance of furnace door opening to the furnace pressure and temperature detection values.

[0121] In one example, the data acquisition module, heat transfer status judgment module, status comparison module, combustion control module, and door opening compensation module can be integrated into the PLC, industrial controller, DCS control system, or other control device with data acquisition and control output functions of the aluminum profile melting furnace. Each module can be implemented using software programs, hardware circuits, or a combination of both. The above module division is only used to illustrate the logical relationship between the functions and does not limit the modules to being physically independent of each other.

[0122] In some embodiments, the energy-saving intelligent control system of the aluminum profile melting furnace further includes a safety limiting module and an execution adjustment module.

[0123] The safety limiting module is used to acquire furnace pressure, flue gas temperature, flame detection signal, and gas pressure, and to determine whether the smelting furnace meets the safe operating conditions based on these parameters. Specifically, furnace pressure can be acquired by a furnace pressure transmitter, flue gas temperature can be acquired by a temperature detection element installed in the flue gas channel or flue, flame detection signal can be provided by a flame detector, burner controller, or combustion safety interlock device, and gas pressure can be acquired by a pressure detection element on the gas pipeline.

[0124] When at least one of the following conditions—furnace pressure, flue gas temperature, flame detection signal, and gas pressure—is met, the safety limiting module adjusts the gas output, combustion air output, and flue gas side opening to a preset safety control state. The abnormal conditions may include: furnace pressure exceeding a preset safe pressure range, flue gas temperature exceeding a preset upper temperature limit, an abnormal flame detection signal, or gas pressure below a preset lower limit or above a preset upper limit. The preset safety control state can be set according to the type of abnormality. For example, when the furnace pressure is too low, the flue gas side suction intensity is reduced and the increase in combustion air output is limited; when the furnace pressure is too high, the increase in gas output is limited and the flue gas side opening is increased; when the flue gas temperature is too high, the gas output is reduced; when the flame detection signal or gas pressure is abnormal, the energy-saving intelligent control is exited and combustion safety interlock control is activated.

[0125] The execution adjustment module includes a gas adjustment unit, a combustion air adjustment unit, and a smoke exhaust adjustment unit. The gas adjustment unit adjusts the gas output, which can be expressed as the gas valve opening, a gas flow setpoint, or a burner load percentage. The combustion air adjustment unit adjusts the combustion air output, which can be expressed as the combustion air fan frequency, the combustion air valve opening, or a combustion air flow setpoint. The smoke exhaust adjustment unit adjusts the smoke exhaust side opening, which can be expressed as the smoke exhaust valve opening, the flue damper opening, or the induced draft fan frequency.

[0126] In one example, the gas regulating unit can adjust the gas valve opening according to the gas output target value output by the combustion control module; the combustion air regulating unit can adjust the combustion air fan frequency or combustion air valve opening according to the combustion air output target value output by the combustion control module; and the smoke exhaust regulating unit can adjust the smoke exhaust valve, flue damper or induced draft fan according to the smoke exhaust regulating command output by the door opening compensation module or the safety limiting module to change the smoke exhaust side suction intensity.

[0127] In one example, the safety limiting module can also limit the rate of change of the output of the control module. For example, within adjacent control cycles, the changes in the gas valve opening, combustion air fan frequency, and flue gas valve opening shall not exceed their respective preset limits. This setting can prevent sudden changes in gas output, combustion air output, or flue gas side opening, reducing the risk of furnace pressure fluctuations and flame instability.

[0128] By setting up a safety limiting module and an execution adjustment module, the energy-saving intelligent control system can perform heat transfer state judgment, combustion control, and door opening compensation control while simultaneously imposing safety constraints on furnace pressure, flue gas temperature, flame state, and gas pressure. This allows the gas output, combustion air output, and flue gas side opening to be adjusted within a safe range, thereby improving the operational safety and engineering applicability of the energy-saving intelligent control system for aluminum profile smelting furnaces.

[0129] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0130] 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 protection scope of the present invention.

Claims

1. An energy-saving intelligent control method for an aluminum profile smelting furnace, characterized in that, Includes the following steps: Collect data on the furnace top temperature, furnace bottom temperature, furnace door status, gas output, and combustion air output of the aluminum smelting furnace; When the furnace door is closed, the temperature difference between the furnace top and the furnace bottom is calculated based on the furnace top temperature and the furnace bottom temperature, and the heat transfer status judgment value is calculated based on the change in the temperature difference, the gas output and the combustion air output. The heat transfer status judgment value is compared with the preset judgment conditions to determine whether the furnace is in a normal heat transfer state or a state of blocked heat transfer. When it is determined that the furnace is in a normal heat transfer state, the gas output and combustion air output are controlled according to the first control strategy; when it is determined that the furnace is in a state of hindered heat transfer, the gas output and combustion air output are controlled according to the second control strategy, wherein the second control strategy reduces the gas output and limits the combustion air output compared to the first control strategy. When the furnace door is opened, the update of the heat transfer status judgment value is paused, and door opening compensation control is executed.

2. The method according to claim 1, characterized in that, The calculation of the heat transfer state judgment value includes: The change in temperature difference is determined based on the temperature difference between the top and bottom of the furnace in the current calculation cycle and the temperature difference between the top and bottom of the furnace in the previous calculation cycle or within a preset time window. The temperature difference change is corrected based on the gas output and the combustion air output. The heat transfer state judgment value is calculated based on the temperature difference between the furnace top and bottom and the corrected temperature difference change.

3. The method according to claim 1, characterized in that, The preset judgment conditions include a first judgment threshold and a second judgment threshold, wherein the second judgment threshold is greater than the first judgment threshold; When the heat transfer state judgment value is greater than the second judgment threshold and continues to reach the first set time, it is determined that the furnace is in a state of heat transfer obstruction. When the heat transfer status judgment value is less than the first judgment threshold and continues to reach the second set time, it is determined that the furnace is in a normal heat transfer state.

4. The method according to claim 1, characterized in that, The first control strategy includes: The target value for gas output is determined based on the deviation between the furnace bottom temperature and the target smelting temperature, and the gas output is adjusted according to the target value. The target value for combustion air output is determined based on the target value for gas output, and the output amount of combustion air is adjusted according to the target value for combustion air output. When the furnace top temperature reaches the preset upper limit, the target value of gas output is limited from continuing to increase.

5. The method according to claim 1, characterized in that, The second control strategy includes: Based on the deviation between the heat transfer state judgment value and the preset judgment condition, the gas output target value is reduced, and the gas output is adjusted according to the reduced gas output target value. The target value for combustion air output is determined based on the reduced target value for gas output, and the output amount of combustion air is adjusted according to the target value for combustion air output. During the implementation period, the increase in the output of combustion air will be limited.

6. The method according to claim 1, characterized in that, The door opening compensation control includes: When the furnace door is opened, the heat transfer status judgment value obtained from the most recent calculation before the furnace door was opened is maintained; The furnace pressure is collected, and the exhaust side actuator is adjusted according to the furnace pressure to reduce the exhaust side suction intensity. When the furnace pressure is lower than the preset lower pressure limit, the increase in combustion air output is restricted; when the furnace pressure is higher than the preset upper pressure limit, the increase in gas output is restricted.

7. The method according to claim 1, characterized in that, When the furnace door returns to the closed state from the open state, a door closing recovery control is executed, which includes: The gas output, combustion air output, and exhaust side opening are restored according to the preset rate of change. After the furnace door is closed and a preset stabilization time has elapsed, the update of the heat transfer state judgment value is resumed. Furthermore, the furnace top and bottom temperatures collected during furnace door opening are not included in the calculation of the heat transfer status judgment value after recovery.

8. The method according to claim 1, characterized in that, During the execution of the first control strategy, the second control strategy, and the door opening compensation control, safety limiting control is performed; The safety limiting control includes: acquiring furnace pressure, flue gas temperature, flame detection signal, and gas pressure; When the furnace pressure exceeds the preset safe pressure range, the flue gas temperature exceeds the preset upper temperature limit, the flame detection signal is abnormal, or the gas pressure is abnormal, the current control strategy is exited, and the gas output, combustion air output, and flue gas side opening are adjusted to the preset safe control state.

9. An energy-saving intelligent control system for an aluminum profile smelting furnace, characterized in that, include: The data acquisition module is used to collect data on the furnace top temperature, furnace bottom temperature, furnace door status, gas output, and combustion air output of the aluminum smelting furnace. The heat transfer status judgment module is used to calculate the temperature difference between the furnace top and the furnace bottom based on the furnace top temperature and the furnace bottom temperature when the furnace door is closed, and to calculate the heat transfer status judgment value based on the change in the temperature difference, the gas output and the combustion air output. The status comparison module is used to compare the heat transfer status judgment value with the preset judgment conditions to determine whether the furnace is in a normal heat transfer state or a heat transfer blocked state. The combustion control module is used to control the gas output and combustion air output according to a first control strategy when it is determined that the furnace is in a normal heat transfer state, and to control the gas output and combustion air output according to a second control strategy when it is determined that the furnace is in a state of heat transfer obstruction, wherein the second control strategy reduces the gas output and limits the combustion air output compared to the first control strategy. The door opening compensation module is used to pause the updating of the heat transfer status judgment value and perform door opening compensation control when the furnace door is opened.

10. The system according to claim 9, characterized in that, It also includes a safety limiting module and an execution adjustment module; The safety limiting module is used to acquire furnace pressure, flue gas temperature, flame detection signal and gas pressure, and when at least one of the furnace pressure, flue gas temperature, flame detection signal and gas pressure meets the abnormal conditions, it adjusts the gas output, combustion air output and flue gas side opening to the preset safety control state. The execution adjustment module includes a gas adjustment unit, a combustion air adjustment unit, and a smoke exhaust adjustment unit. The gas adjustment unit is used to adjust the gas output, the combustion air adjustment unit is used to adjust the combustion air output, and the smoke exhaust adjustment unit is used to adjust the smoke exhaust side opening.

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