Linkage control method and system for combustion fan and gas valve of rotary kiln

Abstract

The invention relates to the technical field of automatic control, in particular to a linkage control method and system for a combustion-supporting fan and a gas valve of a rotary kiln, and the method comprises the steps: obtaining a combustion-supporting air flow sequence, a gas flow sequence and a gas valve opening sequence corresponding to a current time node, respectively carrying out first-order difference processing to obtain a combustion-supporting air flow first-order difference sequence, a gas flow first-order difference sequence and a gas valve opening first-order difference sequence; and outputting the fan frequency of the combustion fan and the opening degree of the gas valve by using an improved active-disturbance-rejection control algorithm, and performing linkage control on the combustion fan and the gas valve based on the fan frequency of the combustion fan and the opening degree of the gas valve. The problem that the control precision is not high under different working conditions is solved.

Description

Technical Field

[0001] This invention relates to the field of automation control technology. More specifically, this invention relates to a method and system for the linkage control of a rotary kiln combustion fan and a gas valve. Background Technology

[0002] Rotary kilns, as core thermal equipment used in industries such as cement, metallurgy, chemicals, and solid waste disposal, rely heavily on the matching relationship between combustion air supply and gas supply for stability and energy efficiency. In actual operation, the combustion conditions inside a rotary kiln are complex, influenced by factors such as fluctuations in raw material composition, changes in feed rate, and variations in environmental conditions, resulting in significant time-varying and nonlinear characteristics in the combustion load. The combustion air fan adjusts its frequency to change the air volume, while the gas valve adjusts its opening to regulate the gas supply intensity; together, they determine the air-fuel ratio and combustion state within the rotary kiln.

[0003] To improve the robustness and disturbance rejection capability of the rotary kiln combustion process, some control systems incorporate active disturbance rejection control (ADRC) algorithms for closed-loop regulation of gas valves or combustion fans. ADRC estimates internal uncertainties and external disturbances through an extended state observer, theoretically achieving good control performance without relying on precise mathematical models, thus possessing certain application value in complex industrial applications.

[0004] However, existing active disturbance rejection control algorithms typically employ a fixed gain vector in engineering applications. This gain is set during system commissioning based on typical operating conditions or empirical parameters, and remains constant once the system is operational. This fixed-gain control method exhibits significant limitations in scenarios involving the coordinated control of the rotary kiln combustion fan and gas valve. Specifically, the dynamic characteristics and disturbance intensity of the rotary kiln combustion system vary significantly under different load ranges and operating stages. When the system is under low load or stable operation, a fixed, large control gain can ensure a fast response speed. However, under complex conditions such as sudden load changes, fuel quality fluctuations, or combustion air lag, excessively high gain can amplify disturbances and measurement noise, causing excessive adjustment of the gas valve and combustion air blower, resulting in drastic fluctuations in the air-fuel ratio, and even combustion oscillations and temperature overshoot. Conversely, if the fixed gain is set too small to avoid drastic oscillations under high load conditions, then when the system is in normal or requires rapid adjustment, it will lead to a slow control response, a lag in the matching adjustment between the combustion air blower and the gas valve, and difficulty in timely eliminating combustion deviations, affecting the production efficiency and thermal utilization rate of the rotary kiln, thus resulting in low control accuracy under different operating conditions. Summary of the Invention

[0005] To address the problem of low control accuracy under different operating conditions mentioned in the background art, the present invention provides solutions in the following aspects.

[0006] In a first aspect, the present invention provides a method for the coordinated control of a rotary kiln combustion fan and a gas valve, comprising: acquiring a combustion fan flow rate sequence, a gas flow rate sequence, and a gas valve opening sequence corresponding to the current time node, and performing first-order differential processing on each to obtain a first-order differential sequence of the combustion fan flow rate, a first-order differential sequence of the gas flow rate, and a first-order differential sequence of the gas valve opening; outputting the fan frequency of the combustion fan and the gas valve opening using an improved active disturbance rejection control algorithm, and performing coordinated control of the combustion fan and the gas valve based on the fan frequency of the combustion fan and the gas valve opening; The improved active disturbance rejection control algorithm includes a gain vector, which is the product of an initial gain vector and an adjustment factor. The adjustment factor is inversely correlated with the degree of anomaly at the current time node, the degree of anomaly is positively correlated with the degree of fluctuation at the current time node, the degree of fluctuation is positively correlated with the time difference between the peak times of the gas valve opening change rate, the first-order difference sequence of gas flow rate, and the first-order difference sequence of combustion air flow rate at the current time node, and is inversely correlated with the mean of the combustion air flow rate data at each time node within the historical set time window with the current time node as the latest point.

[0007] The above technical solution performs time-series analysis on the dynamic changes of combustion air flow, gas flow, and gas valve opening, and combines an improved active disturbance rejection control algorithm to achieve adaptive adjustment of the gain vector according to the degree of anomaly. This enables the combustion air blower and gas valve to coordinately adjust according to the fluctuations and deviations in the combustion state, thereby ensuring rapid response while suppressing over-adjustment. This significantly improves the stability of the rotary kiln combustion process and the air-fuel ratio matching accuracy, increases combustion efficiency, and reduces temperature fluctuations and energy waste.

[0008] Furthermore, time nodes Regulatory factors for: , Time node The degree of abnormality, , Each is a time node Time nodes The residual output of the extended state observer in the active disturbance rejection control algorithm.

[0009] The above technical solution calculates the adjustment factor by combining the current degree of anomaly with the change amplitude of the observer residuals at two consecutive time points. This allows the control gain to automatically decrease when combustion anomalies or disturbances change rapidly, thereby suppressing over-adjustment and oscillations. Meanwhile, it maintains a high gain during stable operation to accelerate the response speed, thus achieving adaptive coordinated control of the combustion fan and gas valve.

[0010] Furthermore, time nodes abnormality for: , Time node The degree of fluctuation, Based on time nodes Set the latest historical point within the time window. The air-fuel ratio in the rotary kiln at each time point To preset the standard air-fuel ratio, Set the total number of time nodes within the set time window for the history.

[0011] The above technical solution calculates the degree of anomaly by combining the degree of combustion fluctuation at the current time point with the magnitude and duration of the deviation of the air-fuel ratio from the standard value over a historical period. This comprehensively reflects the actual deviation of the combustion process at the current moment, thereby accurately identifying the working conditions of mismatch between gas and combustion air supply or continuous accumulation of combustion anomalies.

[0012] Furthermore, time nodes The degree of fluctuation for: , Time node The rate of change of gas valve opening, Time node The time difference between the peak times of the corresponding first-order difference sequences of gas flow rate and combustion air flow rate. This is the average value of the combustion air flow rate data for each time point within a historical time window, with the current time point as the latest point. These are the preset hyperparameters.

[0013] The above technical solution combines the rate of change of the gas valve opening with the time difference of the gas flow and combustion air flow response, and normalizes it with the recent average level of combustion air. This can accurately reflect the actual disturbance intensity of the valve adjustment on the combustion state, thus providing a reliable basis for anomaly identification and subsequent adaptive control.

[0014] Furthermore, the combustion air flow rate sequence, gas flow rate sequence, and gas valve opening sequence corresponding to the current time node are obtained. Specifically, the combustion air flow rate, gas flow rate, and gas valve opening sequence corresponding to the current time node are constructed by obtaining the combustion air flow rate, gas flow rate, and gas valve opening sequence under the current time node and multiple historical time nodes.

[0015] Furthermore, the air-fuel ratio is the ratio of gas flow rate to combustion air flow rate.

[0016] The above technical solution defines the air-fuel ratio as the ratio of gas flow rate to combustion air flow rate, which can intuitively reflect the matching relationship between fuel and combustion air supply during combustion, thereby providing a direct basis for real-time monitoring of combustion status, anomaly judgment, and coordinated adjustment of combustion air fan and gas valve.

[0017] Furthermore, the preset hyperparameter is 1.

[0018] Furthermore, the historical time window is set to 100.

[0019] Furthermore, it also includes denoising and standardizing the combustion air flow sequence, gas flow sequence, and gas valve opening sequence, respectively.

[0020] The above technical solution denoises and standardizes the historical and current sequence data of combustion air flow, gas flow, and gas valve opening, unifying data with different dimensions and variation amplitudes to a comparable scale, effectively eliminating the interference of measurement noise and data fluctuations on the control algorithm.

[0021] In a second aspect, the present invention provides a linkage control system for a rotary kiln combustion fan and a gas valve, comprising a memory and a processor. The memory stores computer program instructions, and when the computer program instructions are executed by the processor, a linkage control method for a rotary kiln combustion fan and a gas valve as described above is implemented.

[0022] The beneficial effects of this invention are as follows: This invention constructs a sequence from historical and current operating data of rotary kiln combustion air flow, gas flow, and gas valve opening, performs first-order differential processing and noise reduction standardization, and combines this with an improved active disturbance rejection control algorithm to achieve adaptive adjustment of gain according to the degree of system anomaly. This enables the combustion air blower and gas valve to dynamically link according to fluctuations in combustion state, air-fuel ratio deviation, and valve adjustment. Thus, under different loads and disturbance conditions, it ensures rapid control response while suppressing over-adjustment and oscillation, effectively improving the stability of the combustion process, the accuracy of air-fuel ratio matching, and thermal energy utilization efficiency. At the same time, it reduces energy consumption and mechanical wear risks, and enhances the robustness and safety of the system under complex operating conditions. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating, schematically, a method for the linkage control of a rotary kiln combustion fan and a gas valve according to an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the residual of a conventional extended state observer for a linkage control method of a rotary kiln combustion fan and a gas valve according to an embodiment of the present invention. Figure 3This is a schematic diagram illustrating the residual of an improved extended state observer for a linkage control method of a rotary kiln combustion fan and a gas valve according to an embodiment of the present invention. Figure 4 This is a schematic block diagram illustrating the structure of a linkage control system for a rotary kiln combustion fan and a gas valve according to an embodiment of the present invention. Detailed Implementation

[0024] An embodiment of a method for the linkage control of a rotary kiln combustion fan and a gas valve.

[0025] like Figure 1 The diagram shown is a flowchart of a method for the linkage control of a rotary kiln combustion fan and a gas valve according to an embodiment of the present invention, including the following steps: S1: Obtain the combustion air flow sequence, gas flow sequence, and gas valve opening sequence corresponding to the current time node.

[0026] In a preferred embodiment, the combustion air flow rate, gas flow rate, and gas valve opening degree corresponding to the current time node are obtained by acquiring the combustion air flow rate, gas flow rate, and gas valve opening degree at the current time node and multiple historical time nodes.

[0027] Furthermore, considering the complex industrial environment, frequent fluctuations in operating conditions, and inherent measurement errors in sensors, the combustion air flow sequence, gas flow sequence, and gas valve opening sequence are preferably preprocessed before being directly used for analysis and control. Specifically, each time series is first denoised. This filters out abnormal fluctuations and high-frequency noise components introduced by factors such as airflow pulsation, instantaneous changes in gas pressure, mechanical vibration of actuators, and electromagnetic interference. This makes the processed data smoother and more continuous, preventing noise signals from being misidentified as actual operating condition changes and affecting the stability and reliability of the control strategy. Denoising effectively improves the signal-to-noise ratio of each parameter's time series, allowing it to more accurately reflect the actual operating patterns of the combustion system.

[0028] After noise reduction, the combustion air flow sequence, gas flow sequence, and gas valve opening sequence are further standardized. This standardization process maps the original data corresponding to different physical quantities to a unified numerical range or statistical distribution, thereby eliminating calculation bias caused by differences in dimensions and numerical ranges.

[0029] S2: Utilizes an improved active disturbance rejection control algorithm to output the fan frequency of the combustion blower and the opening degree of the gas valve.

[0030] In a preferred embodiment, the improved active disturbance rejection control algorithm includes a gain vector, which is the product of an initial gain vector and a regulation factor. By transforming the originally fixed control gain into a dynamic gain jointly determined by the initial setpoint and the real-time regulation factor, under conditions of stable operation, low abnormality, and mild disturbance changes, the regulation factor approaches a larger value, ensuring that the actual gain level involved in the control calculation is close to the initial setpoint. This guarantees that the active disturbance rejection control has sufficient response speed and regulation capability under normal operating conditions. However, when combustion abnormalities, increased fluctuations, or rapid changes in unmodeled disturbances occur, the regulation factor decreases accordingly, compressing the overall control gain and directly reducing the controller's amplification effect on deviations and disturbances, thus avoiding drastic changes in control output caused by excessively high gain.

[0031] Time Node Regulatory factors for: , Time node The degree of abnormality, , Each is a time node Time nodes The residual output of the extended state observer in the active disturbance rejection control algorithm.

[0032] like Figure 2 The diagram shown is a schematic diagram of the residual of a conventional expansion state observer for a linkage control method of a rotary kiln combustion fan and a gas valve according to an embodiment of the present invention.

[0033] like Figure 3 The diagram shown is a schematic diagram of the residual of an improved extended state observer for a linkage control method of a rotary kiln combustion fan and a gas valve according to an embodiment of the present invention.

[0034] By directly incorporating the anomaly level at the current moment and the change amplitude of the observer residual at two consecutive time points in the active disturbance rejection control into the calculation process of the adjustment factor, this method characterizes whether it is appropriate to perform over-regulation or to adopt conservative control at the current moment. When the combustion process is in a state with a high degree of anomaly and the observer residual shows significant changes between adjacent time points, it indicates that the internal unmodeled disturbance or external disturbance is evolving rapidly. At this time, continuing to apply a large control correction is likely to cause over-regulation or oscillation. Therefore, the adjustment factor will be automatically compressed to a smaller value to suppress the change amplitude of the control output. When the anomaly level is low and the change of the observer residual is gradual, it indicates that the operating state is relatively stable and the disturbance change is controllable. The adjustment factor is increased accordingly, so that the control algorithm can play a more full regulatory role and accelerate convergence to the target state.

[0035] Time Node abnormality for: , Time node The degree of fluctuation, Based on time nodes Set the latest historical point within the time window. The air-fuel ratio in the rotary kiln at a given time point, wherein the air-fuel ratio is the ratio of the gas flow rate to the combustion air flow rate. To preset the standard air-fuel ratio, The total number of time nodes within the historical time window is set to 100. Of course, it can also be set according to the actual situation.

[0036] By directly combining the current operational fluctuation level with the degree to which the rotary kiln's air-fuel ratio deviates from the standard state over a historical period, this method characterizes the comprehensive abnormal state of the combustion process at the current time point. When the current time already exhibits significant fluctuation characteristics, any repeated or continuous deviations of the air-fuel ratio from the preset standard air-fuel ratio in recent times will be amplified and manifested as a higher degree of abnormality, reflecting that the combustion regulation imbalance is evolving towards an unstable state. Conversely, when the fluctuation level is small, even if there are some deviations in the air-fuel ratio at individual moments, the impact on the final degree of abnormality will be naturally suppressed, avoiding misjudging short-term, self-recoverable minor deviations as serious anomalies. Furthermore, by employing a weighting method that gradually weakens the weighting of the air-fuel ratio deviations at each time point within the historical time window from near to far, combustion deviations closer to the current time have a higher weight in the anomaly calculation, while the impact of earlier deviations that have already been corrected by subsequent adjustments is effectively weakened, thus making the degree of abnormality more closely reflect the actual evolution of combustion.

[0037] Time Node The degree of fluctuation for: , Time node The rate of change of gas valve opening, Time node The time difference between the peak times of the corresponding first-order difference sequences of gas flow rate and combustion air flow rate. This is the average value of the combustion air flow rate data for each time point within a historical time window, with the current time point as the latest point. The preset hyperparameter is 1, but it can also be set according to the actual situation.

[0038] By visually reflecting at each time point whether the current valve adjustment has caused asynchronous responses between the gas and combustion air, this provides a clear and usable quantitative basis for limiting the valve adjustment range, reducing combustion fluctuations, and improving combustion stability in subsequent control. When the gas valve adjusts rapidly within a short period, and the peak values ​​of the gas flow rate change and the combustion air flow rate change show a significant time discrepancy, it indicates that the current control action has caused asynchronous gas supply responses within the combustion system, which can easily lead to significant fluctuations in the combustion state. Therefore, the corresponding fluctuation level will be calculated as large. Conversely, when the valve adjustment changes slowly, the peak values ​​of the gas and combustion air changes are close in time, and the overall combustion air supply level is relatively stable, the fluctuation level obtained is small, indicating that the current combustion process is in a relatively stable state. At the same time, by introducing the average value of the combustion air flow rate over a historical period to constrain the results, it is possible to avoid distortion in fluctuation judgments due to differences in the flow rate base under high or low load conditions.

[0039] S3: Based on the fan frequency of the combustion fan and the opening degree of the gas valve, the combustion fan and the gas valve are linked for control.

[0040] In a preferred embodiment, the combustion fan and gas valve are linked under control based on the fan frequency and gas valve opening to achieve dynamic coordination between combustion air supply and gas supply during combustion. Specifically, the current fan frequency of the combustion fan is continuously acquired to characterize its actual air delivery capacity and combustion air supply level. Simultaneously, the current opening state of the gas valve is acquired to reflect the instantaneous intensity and adjustment trend of the gas supply. Based on this, both are used as core adjustment variables for comprehensive analysis and coordinated adjustment in the linked control. When the gas valve opening changes, the control system synchronously adjusts the operating frequency of the combustion fan according to the magnitude and direction of the change, ensuring that the combustion air volume matches the changes in gas supply in a timely manner. This avoids incomplete combustion due to increased gas supply causing a delay in combustion air supply, or decreased combustion efficiency due to excessive combustion air supply.

[0041] The present invention serializes, denoises, and standardizes the historical and current operating data of the rotary kiln combustion blower and gas valves, and combines this with an improved active disturbance rejection control algorithm to achieve adaptive adjustment of gain according to the degree of system anomaly. This enables the combustion blower and gas valves to perform real-time coordinated adjustment based on combustion fluctuations and air-fuel ratio deviations, ensuring rapid response while suppressing over-adjustment and oscillations. This significantly improves the stability of the combustion process, the accuracy of air-fuel ratio matching, and fuel utilization efficiency, while reducing the risks of temperature fluctuations, energy consumption, and equipment wear, and enhancing the control robustness and operational safety of the rotary kiln under complex operating conditions.

[0042] An embodiment of a linkage control system for a rotary kiln combustion fan and a gas valve: like Figure 4 As shown in the diagram, a structural block diagram of a linkage control system for a rotary kiln combustion fan and a gas valve according to an embodiment of the present invention includes a processor and a memory. The memory stores computer program instructions, which, when executed by the processor, implement the linkage control method for a rotary kiln combustion fan and a gas valve according to the present invention.

[0043] The linkage control system for the rotary kiln combustion fan and gas valve also includes other components well known to those skilled in the art, such as communication interfaces. Their settings and functions are known in the art and will not be described in detail here.

[0044] In this invention, the aforementioned memory can be any tangible medium containing or storing a program that can be used or combined with an instruction execution system, apparatus, or device. For example, a computer-readable storage medium can be any suitable magnetic or magneto-optical storage medium, such as Resistive Random Access Memory (RRAM), Dynamic Random Access Memory (DRAM), Static Random Access Memory (SRAM), Enhanced Dynamic Random Access Memory (EDRAM), High-Bandwidth Memory (HBM), Hybrid Memory Cube (HMC), etc., or any other medium that can be used to store desired information and can be accessed by an application, module, or both. Any such computer storage medium can be part of a device or accessible to or connected to a device. Any application or module described in this invention can be implemented using computer-readable / executable instructions stored or otherwise maintained by such a computer-readable medium.

[0045] In the description of this specification, "multiple" or "several" means at least two, such as two, three or more, unless otherwise explicitly specified.

[0046] While this specification has shown and described numerous embodiments of the invention, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and essence of the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in the practice of this invention.

Claims

1. A method for the linkage control of a rotary kiln combustion fan and a gas valve, characterized in that, include: Obtain the combustion air flow rate sequence, gas flow rate sequence, and gas valve opening sequence corresponding to the current time node, and perform first-order difference processing on each to obtain the first-order difference sequence of combustion air flow rate, gas flow rate, and gas valve opening sequence. An improved active disturbance rejection control algorithm is used to output the fan frequency of the combustion blower and the opening degree of the gas valve, and the combustion blower and the gas valve are linked for control based on the fan frequency of the combustion blower and the opening degree of the gas valve. The improved active disturbance rejection control algorithm includes a gain vector, which is the product of an initial gain vector and an adjustment factor. The adjustment factor is inversely correlated with the degree of anomaly at the current time node, the degree of anomaly is positively correlated with the degree of fluctuation at the current time node, the degree of fluctuation is positively correlated with the time difference between the peak times of the gas valve opening change rate, the first-order difference sequence of gas flow rate, and the first-order difference sequence of combustion air flow rate at the current time node, and is inversely correlated with the mean of the combustion air flow rate data at each time node within the historical set time window with the current time node as the latest point.

2. The method for linkage control of rotary kiln combustion fan and gas valve according to claim 1, characterized in that, Time Node Regulatory factors for: , Time node The degree of abnormality, , Each is a time node Time nodes The residual output of the extended state observer in the active disturbance rejection control algorithm.

3. The method for linkage control of rotary kiln combustion fan and gas valve according to claim 1, characterized in that, Time Node abnormality for: , Time node The degree of fluctuation, Based on time nodes Set the latest historical point within the time window. The air-fuel ratio in the rotary kiln at each time point To preset the standard air-fuel ratio, Set the total number of time nodes within the set time window for the history.

4. The method for linkage control of rotary kiln combustion fan and gas valve according to claim 1, characterized in that, Time Node The degree of fluctuation for: , Time node The rate of change of gas valve opening, Time node The time difference between the peak times of the corresponding first-order difference sequences of gas flow rate and combustion air flow rate. This is the average value of the combustion air flow rate data for each time point within a historical time window, with the current time point as the latest point. These are the preset hyperparameters.

5. The method for linkage control of a rotary kiln combustion fan and a gas valve according to claim 1, characterized in that, To obtain the combustion air flow rate sequence, gas flow rate sequence, and gas valve opening sequence corresponding to the current time node, specifically: by obtaining the combustion air flow rate, gas flow rate, and gas valve opening at the current time node and multiple historical time nodes, the combustion air flow rate sequence, gas flow rate sequence, and gas valve opening sequence corresponding to the current time node are constructed.

6. The method for linkage control of rotary kiln combustion fan and gas valve according to claim 3, characterized in that, The air-fuel ratio is the ratio of the gas flow rate to the combustion air flow rate.

7. The method for linkage control of a rotary kiln combustion fan and a gas valve according to claim 4, characterized in that, The preset hyperparameter is 1.

8. The method for linkage control of a rotary kiln combustion fan and a gas valve according to claim 1, characterized in that, The historical time window is set to 100.

9. The method for linkage control of a rotary kiln combustion fan and a gas valve according to claim 1, characterized in that, It also includes denoising and standardizing the combustion air flow sequence, gas flow sequence, and gas valve opening sequence, respectively.

10. A linkage control system for a rotary kiln combustion fan and a gas valve, characterized in that, It includes a memory and a processor. The memory stores computer program instructions, which, when executed by the processor, implement the linkage control method for a rotary kiln combustion fan and a gas valve as described in any one of claims 1 to 9.

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