Control system and control method for combustion-supporting fan of metallurgical heating furnace

Abstract

The application discloses a kind of metallurgical heating furnace combustion-supporting fan control systems, comprising: sensing unit, for collecting stator temperature, bearing vibration signal and outlet air pressure;Edge analysis unit, calculate temperature change rate, the energy ratio corresponding to bearing fault characteristic frequency is extracted by vibration signal spectrum analysis, and according to the comparison result of temperature change rate and energy ratio and preset threshold value determines fault level;Hierarchical decision unit, according to fault level output predictive maintenance instruction or emergency switching instruction;Non-disturbance spare machine switching execution unit is connected with the circuit breaker and frequency converter of main and spare fan, for disconnecting main fan and starting spare fan after receiving emergency switching instruction.The application combines temperature rise rate and bearing characteristic frequency energy ratio, distinguishes early degradation and critical failure, improves maintenance timeliness.The application also discloses a kind of metallurgical heating furnace combustion-supporting fan control method.

Description

Technical Field

[0001] This invention belongs to the field of industrial automation control and equipment health management technology, specifically relating to a control system and control method for a combustion fan of a metallurgical heating furnace. Background Technology

[0002] Combustion blowers in metallurgical heating furnaces are crucial equipment for ensuring stable combustion and achieving the required thermal efficiency. In actual production, a failure in the combustion blower can directly lead to furnace temperature fluctuations, incomplete combustion, or even unplanned furnace shutdowns, resulting in significant economic losses.

[0003] For example, Chinese patent document CN218376993U discloses a method of setting temperature, vibration, and air pressure measuring points on a heating furnace fan, automatically activating a backup fan or issuing an alarm when any parameter exceeds a preset threshold. This type of method uses fixed thresholds for judgment, triggering action only when a parameter significantly exceeds its limit. It fails to identify early deterioration trends in components, often missing the optimal maintenance window. Furthermore, due to sensor zero-point drift, environmental interference, or instantaneous operating condition fluctuations, the phenomenon of a single parameter briefly exceeding the threshold occurs frequently, leading to system misjudgments and unnecessary backup switchovers or alarms, which in turn affects normal production.

[0004] Chinese patent document CN114893428A discloses a multi-parameter acquisition system for fan vibration and temperature, which uses FFT transform to extract spectral features and combines them with health scores to generate a maintenance plan. However, this solution mainly focuses on maintenance strategy formulation and does not address the automatic, seamless switching control between the main and standby fans in the combustion process of the heating furnace, nor does it disclose how to directly use the spectral diagnostic results for the standby fan switching logic. This means that when the main fan suddenly experiences a serious failure, it is still impossible to quickly and smoothly switch to the standby fan, making it difficult to meet the requirement of uninterrupted combustion air pressure for continuous production.

[0005] This invention provides a control system and control method for a combustion fan in a metallurgical heating furnace, with particular emphasis on how to improve the timeliness of maintenance. Summary of the Invention

[0006] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides a combustion fan control system for a metallurgical heating furnace, with the purpose of improving the timeliness of maintenance.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a combustion fan control system for a metallurgical heating furnace, comprising: The sensing unit is used to collect the stator temperature, bearing vibration signal, and outlet air pressure of the combustion fan. An edge analysis unit, connected to the sensing unit, is used to calculate the temperature change rate based on the stator temperature, perform spectral analysis on the bearing vibration signal to extract the energy ratio corresponding to the bearing fault characteristic frequency, and determine the fault level based on the comparison results of the temperature change rate and the energy ratio with a preset threshold. A hierarchical decision-making unit, connected to the edge analysis unit, is used to output predictive maintenance instructions or emergency switchover instructions based on the fault level; and The non-disruptive standby unit is connected to the hierarchical decision-making unit and the circuit breakers and frequency converters of the main fan and the standby fan. It is used to disconnect the main fan and start the standby fan after receiving an emergency switching command.

[0008] The sensing unit includes a Pt100 thermal resistor installed in the three-phase winding of the wind turbine stator, an acceleration sensor installed in the horizontal and / or vertical direction of the bearing housings at the drive end and non-drive end, and a wind pressure transmitter installed at the wind turbine outlet.

[0009] The bearing fault characteristic frequency includes at least one of the following: bearing outer ring fault frequency BPFO, inner ring fault frequency BPFI, rolling element fault frequency BSF, and cage fault frequency FTF; the energy ratio is the ratio of the energy in the frequency band corresponding to the characteristic frequency to the total energy of the entire frequency band.

[0010] The preset threshold includes a first temperature change rate threshold and a second temperature change rate threshold, wherein the second temperature change rate threshold is higher than the first temperature change rate threshold. The edge analysis unit determines a first fault level when the temperature change rate exceeds a first temperature change rate threshold and the energy ratio exceeds a first energy ratio threshold, and determines a second fault level when the temperature change rate exceeds a second temperature change rate threshold and the effective vibration value exceeds a critical limit threshold or the main fan current is detected to be zero.

[0011] The hierarchical decision-making unit outputs predictive maintenance instructions based on the first fault level. The predictive maintenance instructions include automatically generating maintenance work orders and transmitting them to the manufacturing execution system; and outputting emergency switchover instructions based on the second fault level.

[0012] The edge analysis unit is integrated into the edge smart gateway, which is communicatively connected to the programmable logic controller (PLC). The PLC is connected to the non-disruptive standby switching execution unit. The edge analysis unit performs fast Fourier transform on the vibration signal and calculates the sliding window slope of the temperature sequence, and sends the fused fault level signal to the PLC.

[0013] The predictive maintenance instructions output by the hierarchical decision-making unit are at least one of the following forms: information pushed to the mobile terminal, records stored in the local database, or audio-visual prompts.

[0014] The present invention also provides a method for controlling the combustion fan of a metallurgical heating furnace, comprising the following steps: Step 1: Collect the stator temperature, bearing vibration signal, and outlet air pressure of the combustion fan; Step 2: Calculate the temperature change rate based on the stator temperature, and perform spectral analysis on the bearing vibration signal to extract the energy ratio corresponding to the bearing fault characteristic frequency; Step 3: When the temperature change rate exceeds the first threshold and the energy ratio exceeds the first energy ratio threshold, output a predictive maintenance command; when the temperature change rate exceeds the second threshold and the effective vibration value exceeds the critical limit threshold or the main fan current returns to zero, output an emergency switching command. Step 4: In response to the emergency switchover command, execute the non-disruptive standby switchover sequence. First, disconnect the main fan. After confirming that the main fan is disconnected from the grid and the wind pressure has dropped, close the standby fan and use the frequency converter soft start method to increase the speed of the standby fan to the frequency or air volume that matches the original operating state of the main fan.

[0015] The bearing fault characteristic frequency includes at least one of the following: bearing outer ring fault frequency BPFO, inner ring fault frequency BPFI, rolling element fault frequency BSF, and cage fault frequency FTF; the energy ratio is the ratio of the energy in the frequency band corresponding to the characteristic frequency to the total energy of the entire frequency band.

[0016] The combustion fan control system for metallurgical heating furnaces of the present invention uses the stator temperature rise rate dT / dt and the fault characteristic frequency energy ratio extracted by FFT from the bearing housing vibration signal as a joint judgment condition to distinguish between early deterioration trends and critical faults, thereby increasing the advance of fault identification and improving the timeliness of maintenance. Attached Figure Description

[0017] This manual includes the following figures, which illustrate the following: Figure 1 This is a schematic diagram of the control system for the combustion fan of the metallurgical heating furnace of the present invention; The diagram is labeled as follows: 100 - Sensing Unit; 200 - Edge Analysis Unit; 300 - Hierarchical Decision-Making Unit; 400 - Uninterrupted Standby Unit Switching Execution Unit; 500 - Main Fan; 600 - Standby Fan; 700 - Heating Furnace; 800 - ... Detailed Implementation

[0018] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solutions of the present invention, and to facilitate its implementation.

[0019] This invention provides a control system for a combustion fan in a metallurgical heating furnace, comprising: The sensing unit is used to collect the stator temperature, bearing vibration signal, and outlet air pressure of the combustion fan. An edge analysis unit, connected to the sensing unit, is used to calculate the temperature change rate based on the stator temperature, perform spectral analysis on the bearing vibration signal to extract the energy ratio corresponding to the bearing fault characteristic frequency, and determine the fault level based on the comparison results of the temperature change rate and the energy ratio with a preset threshold. A hierarchical decision-making unit, connected to the edge analysis unit, is used to output predictive maintenance instructions or emergency switchover instructions based on the fault level; and The non-disruptive standby unit is connected to the hierarchical decision-making unit and the circuit breakers and frequency converters of the main fan and the standby fan. It is used to disconnect the main fan and start the standby fan after receiving an emergency switching command.

[0020] The sensing unit includes a Pt100 thermal resistor installed in the three-phase winding of the wind turbine stator, an acceleration sensor installed in the horizontal and / or vertical direction of the bearing housings at the drive end and non-drive end, and a wind pressure transmitter installed at the wind turbine outlet.

[0021] The bearing fault characteristic frequency includes at least one of the following: bearing outer ring fault frequency BPFO, inner ring fault frequency BPFI, rolling element fault frequency BSF, and cage fault frequency FTF; the energy ratio is the ratio of the energy in the frequency band corresponding to the characteristic frequency to the total energy of the entire frequency band.

[0022] The preset threshold includes a first temperature change rate threshold and a second temperature change rate threshold, wherein the second temperature change rate threshold is higher than the first temperature change rate threshold. The edge analysis unit determines a first fault level when the temperature change rate exceeds a first temperature change rate threshold and the energy ratio exceeds a first energy ratio threshold, and determines a second fault level when the temperature change rate exceeds a second temperature change rate threshold and the effective vibration value exceeds a critical limit threshold or the main fan current is detected to be zero.

[0023] The hierarchical decision-making unit outputs predictive maintenance instructions based on the first fault level. The predictive maintenance instructions include automatically generating maintenance work orders and transmitting them to the manufacturing execution system; and outputting emergency switchover instructions based on the second fault level.

[0024] The edge analysis unit is integrated into the edge smart gateway, which is communicatively connected to the programmable logic controller (PLC). The PLC is connected to the non-disruptive standby switching execution unit. The edge analysis unit performs fast Fourier transform on the vibration signal and calculates the sliding window slope of the temperature sequence, and sends the fused fault level signal to the PLC.

[0025] The predictive maintenance instructions output by the hierarchical decision-making unit are at least one of the following forms: information pushed to the mobile terminal, records stored in the local database, or audio-visual prompts.

[0026] The present invention also provides a method for controlling the combustion fan of a metallurgical heating furnace, comprising the following steps: Step 1: Collect the stator temperature, bearing vibration signal, and outlet air pressure of the combustion fan; Step 2: Calculate the temperature change rate based on the stator temperature, and perform spectral analysis on the bearing vibration signal to extract the energy ratio corresponding to the bearing fault characteristic frequency; Step 3: When the temperature change rate exceeds the first threshold and the energy ratio exceeds the first energy ratio threshold, output a predictive maintenance command; when the temperature change rate exceeds the second threshold and the effective vibration value exceeds the critical limit threshold or the main fan current returns to zero, output an emergency switching command. Step 4: In response to the emergency switchover command, execute the non-disruptive standby switchover sequence. First, disconnect the main fan. After confirming that the main fan is disconnected from the grid and the wind pressure has dropped, close the standby fan and use the frequency converter soft start method to increase the speed of the standby fan to the frequency or air volume that matches the original operating state of the main fan.

[0027] The bearing fault characteristic frequency includes at least one of the following: bearing outer ring fault frequency BPFO, inner ring fault frequency BPFI, rolling element fault frequency BSF, and cage fault frequency FTF; the energy ratio is the ratio of the energy in the frequency band corresponding to the characteristic frequency to the total energy of the entire frequency band. Example

[0028] Firstly, such as Figure 1 As shown, this embodiment provides a control system for a combustion fan in a metallurgical heating furnace, including: The sensing unit is used to collect the stator temperature, bearing vibration signal, and outlet air pressure of the combustion fan. The edge analysis unit, connected to the sensing unit, is used to calculate the temperature change rate based on the stator temperature, perform spectral analysis on the bearing vibration signal to extract the energy ratio corresponding to the bearing fault characteristic frequency, and determine the fault level based on the comparison results of the temperature change rate and energy ratio with a preset threshold. A hierarchical decision-making unit, connected to an edge analysis unit, is used to output predictive maintenance instructions or emergency switchover instructions based on the fault level; and The non-disruptive standby unit is connected to the hierarchical decision-making unit, as well as the circuit breakers and frequency converters of the main fan and the standby fan. It is used to disconnect the main fan and start the standby fan after receiving an emergency switching command.

[0029] Specifically, the metallurgical heating furnace combustion fan control system provided in this embodiment is physically divided into four layers: a sensing layer, an edge computing layer, a decision execution layer, and an execution layer. The sensing layer consists of temperature sensors, vibration sensors, and air pressure transmitters installed on the main and standby combustion fans, used to collect multi-physical quantity signals reflecting the fan's operating status in real time. The edge computing layer receives the raw signals from the sensing layer, performs temperature change rate calculations, fast Fourier transforms of vibration waveforms, and energy extraction of bearing fault characteristic frequencies near the data source, and outputs a preliminary fault level indicator based on preset fusion criteria. The decision execution layer is typically handled by a programmable logic controller (PLC) or industrial control computer, receiving the judgment results from the edge computing layer and generating predictive maintenance instructions or emergency switching instructions based on process interlocking conditions. The execution layer mainly includes circuit breakers, frequency converters, and automatic switching devices for the main and standby fans, used to perform specific operations such as fan power-off, power-on, and soft-start.

[0030] In this embodiment, the combustion fan of a 1450mm hot rolling mill heating furnace is used as an example for illustration. The heating furnace is equipped with two combustion fans of the same model, namely a main fan and a standby fan, one for use and one for standby. The rated power of each fan is 315kW, the rated voltage is 380V, and they are driven by frequency converters. During normal operation, the outlet air pressure is controlled between 2.5kPa and 3.5kPa.

[0031] Three Pt100 platinum resistance thermometers are embedded in each of the three-phase stator windings of each wind turbine, with at least one installed in each phase winding. The Pt100 has an accuracy class of A, a measurement range of -50℃ to +300℃, and its output resistance signal is fed into the temperature transmitter. The signal from the temperature transmitter is then connected to the input channel of the edge smart gateway. The sampling period is set to 1 second, meaning one temperature value is recorded every second. To facilitate the calculation of the temperature change rate, a 60-second sliding window is maintained within the edge smart gateway to store the 60 most recent temperature sampling points in real time.

[0032] Accelerometers are installed on both the drive-end and non-drive-end bearing housings of each wind turbine. Considering that bearing failures may manifest simultaneously in both the horizontal and vertical directions, this embodiment installs one IEPE piezoelectric accelerometer in each bearing housing in both the horizontal and vertical directions. The sensor output signals are connected to the synchronous sampling channel of the edge smart gateway via cables, with the sampling frequency set to 5kHz to meet the requirements for analyzing the bearing's characteristic frequencies. To ensure data validity, a 2048-point vibration waveform is acquired every 2 seconds for subsequent spectrum analysis.

[0033] A wind pressure transmitter with a range of 0~10kPa is installed at the outlet duct of each blower near the furnace inlet. The wind pressure signal is simultaneously connected to the edge intelligent gateway and the analog input module of the PLC. The former is used for time correlation analysis with vibration and temperature data, and the latter is used for judging wind pressure drop during standby switching and confirming wind pressure recovery after switching is completed.

[0034] The edge analytics unit's functions are performed by an edge smart gateway. This embodiment uses an industrial-grade edge gateway based on an ARM Cortex-A72 processor, with a built-in Linux real-time operating system and pre-installed FFT algorithm library and data processing middleware. The gateway is electrically isolated from field sensors via a safety barrier and exchanges data with the Siemens S7-1500 PLC via the Profinet protocol.

[0035] In this embodiment, the temperature change rate (dT / dt) represents the rate of change of the stator winding temperature over time, typically expressed in °C / min. The temperature sampling period is set to 1 second, meaning one temperature value is recorded every second. A sliding window of 60 seconds is maintained within the edge smart gateway, continuously storing the 60 most recent temperature sampling points. Let the temperature value at the current sampling moment be T. n The temperature value at the m-th sampling point is T. n-m The rate of temperature change is calculated using the following formula: dT / dt = (T n - T n-m ) / (m * Δt sample ) Among them, T n This is the current sampled temperature value. T n-m This represents the temperature value of the m-th sampling point. m is the number of sampling point intervals within the calculation window. By setting m=60, the temperature rise rate per minute (°C / min) can be directly calculated using the temperature change within one minute. Δt sample For the temperature sampling period, Δt sample =1s.

[0036] The edge smart gateway updates the dT / dt value every second, that is, every time a new temperature sampling point T is obtained. n It calculates the current rate of temperature rise and stores the results for trend analysis.

[0037] In the subsequent fusion criteria, two temperature change rate thresholds are preset: the first temperature change rate threshold (early warning threshold) is set at 0.5℃ / min to identify early deterioration trends in bearings; the second temperature change rate threshold (emergency threshold) is set at 3.0℃ / min to identify critical faults requiring immediate switching to a backup unit. When the calculated dT / dt exceeds the corresponding threshold, the edge gateway participates in the fault level determination accordingly.

[0038] For a 2048-point vibration waveform sampled every 2 seconds (sampling frequency 5kHz, corresponding to a sampling duration of approximately 0.4096 seconds), the edge gateway first performs DC removal and windowing processing, and then performs a 2048-point fast Fourier transform to obtain a spectrum from 0Hz to 2500Hz.

[0039] In this embodiment, the bearing failure characteristic frequency includes at least one of the bearing outer ring failure frequency BPFO, inner ring failure frequency BPFI, rolling element failure frequency BSF, and cage failure frequency FTF; the energy ratio is the ratio of the energy in the frequency band corresponding to the characteristic frequency to the total energy of the entire frequency band.

[0040] After obtaining the spectrum, the edge gateway uses ±5% of the theoretical value of each characteristic frequency as the fault characteristic frequency band. For example, for the bearing outer race fault frequency BPFO, the frequency band ranges from 0.95 to 1.05 times the theoretical value. The sum of the squares of the amplitudes of all frequency components within this frequency band is calculated as the characteristic frequency band energy E. BPFO Simultaneously, the sum of the squares of the amplitudes of all frequency components across the entire frequency band (0~2500Hz) is calculated as the total energy E. total The characteristic frequency band energy ratio of the bearing outer ring is defined as: R BPFO = E BPFO / E total Among them, R BPFO This represents the characteristic frequency of bearing outer ring failure. When this ratio R... BPFO If the value continuously exceeds 0.3 (i.e., the first energy ratio threshold), it is determined that there are early failure characteristics in the outer ring of the bearing.

[0041] Similarly, the characteristic frequency band energy ratio of the bearing inner ring is defined as: R BPFI = E BPFI / E total Among them, R BPFI This represents the characteristic frequency of bearing inner ring failure. When this ratio R...BPFI When the energy ratio consistently exceeds 0.3 (i.e., the first energy ratio threshold), it is determined that there are early failure characteristics in the inner ring of the bearing. BPFI This refers to the characteristic frequency band energy of the bearing inner ring fault.

[0042] The characteristic frequency band energy ratio of bearing rolling elements is defined as: R BSF = E BSF / E total Among them, R BSF This represents the characteristic frequency of bearing rolling element failure. When this ratio R... BSF When the energy ratio consistently exceeds 0.3 (i.e., the first energy ratio threshold), it is determined that the bearing rolling elements exhibit early failure characteristics. BSF This refers to the characteristic frequency band energy of bearing rolling element failure.

[0043] The characteristic frequency band energy ratio of a bearing cage is defined as: R FTF = E FTF / E total Among them, R FTF This represents the characteristic frequency of bearing cage failure. When this ratio R... FTF If the energy ratio consistently exceeds 0.3 (i.e., the first energy ratio threshold), it is determined that the bearing cage exhibits early failure characteristics. FTF This refers to the characteristic frequency band energy of bearing cage failure.

[0044] For rolling bearings in actual operation, it is usually not necessary to monitor all four characteristic frequencies at the same time. In this embodiment, the outer ring failure frequency BPFO and the inner ring failure frequency BPFI are preferred as the main criteria because outer ring and inner ring failures are the most common failure modes of combustion fan bearings.

[0045] In this embodiment, the edge gateway has a built-in hierarchical fusion criterion logic that combines the temperature change rate with the vibration characteristic frequency energy ratio, while also referencing the effective vibration value (RMS) and the motor current signal to output a fault level flag.

[0046] In this embodiment, the preset threshold includes a first temperature change rate threshold and a second temperature change rate threshold, wherein the second temperature change rate threshold is higher than the first temperature change rate threshold. The edge analysis unit determines the first fault level when the temperature change rate exceeds the first temperature change rate threshold and the energy ratio exceeds the first energy ratio threshold, and determines the second fault level when the temperature change rate exceeds the second temperature change rate threshold and the effective value of vibration exceeds the critical limit threshold or the main fan current is detected to be zero.

[0047] Specifically, the judgment logic is as follows: (1) When both "dT / dt ≥ 0.5℃ / min" and "bearing outer ring characteristic frequency energy ratio R" are satisfied, BPFO ≥0.3 or inner ring characteristic frequency energy ratio R BPFI If the value is ≥ 0.3” but the emergency condition has not yet been met, a “Level 2 Warning” flag will be output. The “Level 2 Warning” flag corresponds to the first fault level and the early fault trend.

[0048] (2) When the conditions "dT / dt ≥ 3.0℃ / min and (vibration RMS ≥ 8.0 mm / s or motor current returns to zero)" are met, a "Level 3 Emergency Switching" flag is output. The "Level 3 Emergency Switching" flag corresponds to the second fault level. The motor current returning to zero signal is determined by combining the auxiliary contact of the main fan circuit breaker and the measured value of the current transformer through the PLC to avoid misjudgment due to the current transformer being disconnected.

[0049] Level 1 warnings are within safe limits, such as during prolonged operation at maximum load. In such cases, the load can be manually reduced to normalize the fan temperature. Regarding vibration, during fan surge, adjustments can be made by changing the damper, controlling the air intake, or opening vents. Since the warning values ​​do not show an upward trend, Level 1 warnings do not consider interlocking records. This embodiment primarily considers warnings caused by equipment deterioration.

[0050] In this embodiment, the hierarchical decision-making unit outputs predictive maintenance instructions based on the first fault level. These instructions include automatically generating maintenance work orders and transmitting them to the manufacturing execution system. It also outputs emergency switching instructions based on the second fault level. When the emergency switching criteria are met, a backup fan switching instruction is sent to the execution unit. Simultaneously, pop-up windows and audible / visual alarms are displayed on the human-machine interface (HMI) in the control room.

[0051] The work order includes: equipment number (e.g., "#3 combustion fan"), fault type (e.g., "early peeling trend of drive end bearing"), recommended maintenance action (e.g., "planned shutdown to replace bearing"), estimated remaining life (estimated by the edge gateway based on the changing trends of temperature rise rate and energy ratio, 720 hours in this embodiment), and recommended maintenance window (e.g., "next scheduled maintenance"). After receiving the request, the MES system automatically generates a work order in the maintenance planning module and notifies the equipment inspection personnel.

[0052] The edge analysis unit is integrated into the edge smart gateway, which is connected to the programmable logic controller (PLC). The PLC is connected to the non-disruptive standby switching execution unit. The edge analysis unit performs fast Fourier transform on the vibration signal and calculates the sliding window slope of the temperature sequence, and sends the fused fault level signal to the PLC.

[0053] In this embodiment, the predictive maintenance instructions output by the hierarchical decision unit are at least one of the following forms: information pushed to the mobile terminal, records stored in the local database, or audio-visual prompts.

[0054] In this embodiment, the non-disruptive standby unit switching execution unit mainly includes a power distribution cabinet (ATS cabinet), which contains a main fan circuit breaker QF1, a standby fan circuit breaker QF2, a frequency converter, and a wind pressure relay. After receiving an emergency switching command, the execution unit automatically completes the switching according to the following sequence, without requiring manual intervention throughout the process.

[0055] The non-disruptive standby unit switching execution unit operates according to the following timing sequence after receiving the switching command: Step 1: Disconnect the main fan circuit breaker QF1, and the main fan motor will lose power.

[0056] Step 2: Check that the main fan current is zero and the main fan outlet air pressure drops below the safe air pressure limit to confirm that the main fan has been disconnected from the grid.

[0057] Step 3: Delay and Wait. The PLC executes a delay timer, with the delay time adjustable between 0.5 seconds and 2 seconds. The purpose of this delay is to avoid the instantaneous disturbance to the power grid that may be caused by the arcing generated when the main wind turbine circuit breaker trips.

[0058] Step 4: Close the standby fan circuit breaker, start the standby fan frequency converter, and soft start to the matching condition according to the original host operating frequency / given air volume curve.

[0059] Step 5: After the standby fan outlet air pressure is restored to the allowable range of the process, complete the switching lock.

[0060] It is important to note that some existing technologies employ a method of closing the standby circuit breaker before opening the main circuit breaker or closing it simultaneously. This can lead to the two fans operating in parallel for a short period, potentially causing motor overcurrent, duct surge, or severe pressure surges in the heating furnace. The sequence adopted in this embodiment—disconnecting the main circuit breaker first, confirming the pressure drop, delaying, and then closing the standby circuit breaker—ensures that only one fan is connected to the power grid and duct at any given time, fundamentally eliminating the risks of parallel operation.

[0061] Secondly, this embodiment also provides a method for controlling the combustion fan of a metallurgical heating furnace, including the following steps: Step 1: Collect the stator temperature, bearing vibration signal, and outlet air pressure of the combustion fan; Step 2: Calculate the temperature change rate based on the stator temperature, and perform spectral analysis on the bearing vibration signal to extract the energy ratio corresponding to the bearing fault characteristic frequency; Step 3: When the temperature change rate exceeds the first threshold and the energy ratio exceeds the first energy ratio threshold, output a predictive maintenance command; when the temperature change rate exceeds the second threshold and the effective value of vibration exceeds the critical limit threshold or the main fan current returns to zero, output an emergency switching command. Step 4: In response to the emergency switchover command, execute the non-disruptive standby switchover sequence. First, disconnect the main fan. After confirming that the main fan is disconnected from the grid and the wind pressure has dropped, close the standby fan and use the frequency converter soft start method to increase the speed of the standby fan to the frequency or air volume that matches the original operating state of the main fan.

[0062] In step two, the bearing failure characteristic frequency includes at least one of the following: bearing outer ring failure frequency BPFO, inner ring failure frequency BPFI, rolling element failure frequency BSF, and cage failure frequency FTF; the energy ratio is the ratio of the energy in the frequency band corresponding to the characteristic frequency to the total energy of the entire frequency band.

[0063] In step four, the specific timing sequence for switching on the standby fan without disturbance is as follows: disconnect the main fan circuit breaker → check that the main fan current is zero and the outlet air pressure is lower than the lower limit of safe air pressure → delay for 0.5 to 2 seconds → close the standby fan circuit breaker and start the standby fan frequency converter → soft start according to the original operating frequency or original air volume curve of the main fan → lock the switchover after the outlet air pressure of the standby fan has recovered to the process allowable range.

[0064] The control system and method for the combustion fan of the metallurgical heating furnace in this embodiment have the following advantages: 1) Achieve fusion criteria: Simultaneously use the ratio of stator temperature rise rate dT / dt to the fault characteristic frequency energy extracted by FFT from the bearing housing vibration signal as a joint judgment condition to distinguish between early deterioration trends and critical faults, thereby increasing the lead time for fault identification.

[0065] 2) Hierarchical mapping logic for predictive maintenance and emergency switching: Based on the above joint criteria, the secondary output is "automatically generate MES work order (without stopping the machine)" and the tertiary output is "trigger standby machine switching without disturbance" - binding the health diagnosis results with the heating furnace main standby switching control logic in a closed loop, overcoming the fragmented defects in the existing technology that only perform diagnosis without issuing switching instructions, or only perform threshold switching without trend prediction.

[0066] 3) Disruption-free standby unit switching sequence: First disconnect the main unit → confirm air pressure drop → set delay → connect the standby unit → the frequency converter soft-starts to the matching condition according to the original main unit operating frequency / air volume setting curve → lock after confirming air pressure recovery. This sequence is specifically designed to prevent combustion vibration in the combustion air system of the heating furnace, which is different from the control logic in existing technologies.

[0067] 4) Decoupled architecture of real-time FFT + slope calculation and PLC interlocking at the edge: high-frequency vibration FFT and dT / dt are completed at the edge gateway. The PLC only receives the "secondary warning / MES work order request" or "third-level switching command" determined by fusion, which reduces the PLC load and improves the response speed.

[0068] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A control system for a combustion fan in a metallurgical heating furnace, characterized in that, include: The sensing unit is used to collect the stator temperature, bearing vibration signal, and outlet air pressure of the combustion fan. An edge analysis unit, connected to the sensing unit, is used to calculate the temperature change rate based on the stator temperature, perform spectral analysis on the bearing vibration signal to extract the energy ratio corresponding to the bearing fault characteristic frequency, and determine the fault level based on the comparison results of the temperature change rate and the energy ratio with a preset threshold. A hierarchical decision-making unit, connected to the edge analysis unit, is used to output predictive maintenance instructions or emergency switching instructions based on the fault level. The non-disruptive standby unit is connected to the hierarchical decision-making unit and the circuit breakers and frequency converters of the main fan and the standby fan. It is used to disconnect the main fan and start the standby fan after receiving an emergency switching command.

2. The combustion fan control system for a metallurgical heating furnace according to claim 1, characterized in that, The sensing unit includes a Pt100 thermal resistor installed in the three-phase winding of the wind turbine stator, an acceleration sensor installed in the horizontal and / or vertical direction of the bearing housings at the drive end and non-drive end, and a wind pressure transmitter installed at the wind turbine outlet.

3. The combustion fan control system for a metallurgical heating furnace according to claim 1, characterized in that, The bearing fault characteristic frequency includes at least one of the following: bearing outer ring fault frequency BPFO, inner ring fault frequency BPFI, rolling element fault frequency BSF, and cage fault frequency FTF; the energy ratio is the ratio of the energy in the frequency band corresponding to the characteristic frequency to the total energy of the entire frequency band.

4. The combustion fan control system for a metallurgical heating furnace according to any one of claims 1 to 3, characterized in that, The preset threshold includes a first temperature change rate threshold and a second temperature change rate threshold, wherein the second temperature change rate threshold is higher than the first temperature change rate threshold. The edge analysis unit determines a first fault level when the temperature change rate exceeds a first temperature change rate threshold and the energy ratio exceeds a first energy ratio threshold, and determines a second fault level when the temperature change rate exceeds a second temperature change rate threshold and the effective vibration value exceeds a critical limit threshold or the main fan current is detected to be zero.

5. The combustion fan control system for a metallurgical heating furnace according to claim 4, characterized in that, The hierarchical decision-making unit outputs predictive maintenance instructions based on the first fault level. The predictive maintenance instructions include automatically generating maintenance work orders and transmitting them to the manufacturing execution system; and outputting emergency switchover instructions based on the second fault level.

6. The combustion fan control system for a metallurgical heating furnace according to any one of claims 1 to 3, characterized in that, The edge analysis unit is integrated into the edge smart gateway, which is communicatively connected to the programmable logic controller (PLC). The PLC is connected to the non-disruptive standby switching execution unit. The edge analysis unit performs fast Fourier transform on the vibration signal and calculates the sliding window slope of the temperature sequence, and sends the fused fault level signal to the PLC.

7. The combustion fan control system for a metallurgical heating furnace according to any one of claims 1 to 3, characterized in that, The predictive maintenance instructions output by the hierarchical decision-making unit are at least one of the following forms: information pushed to the mobile terminal, records stored in the local database, or audio-visual prompts.

8. A method for controlling a combustion fan in a metallurgical heating furnace, characterized in that, Includes the following steps: Step 1: Collect the stator temperature, bearing vibration signal, and outlet air pressure of the combustion fan; Step 2: Calculate the temperature change rate based on the stator temperature, and perform spectral analysis on the bearing vibration signal to extract the energy ratio corresponding to the bearing fault characteristic frequency; Step 3: When the temperature change rate exceeds the first threshold and the energy ratio exceeds the first energy ratio threshold, output a predictive maintenance command; when the temperature change rate exceeds the second threshold and the effective vibration value exceeds the critical limit threshold or the main fan current returns to zero, output an emergency switching command. Step 4: In response to the emergency switchover command, execute the non-disruptive standby switchover sequence. First, disconnect the main fan. After confirming that the main fan is disconnected from the grid and the wind pressure has dropped, close the standby fan and use the frequency converter soft start method to increase the speed of the standby fan to the frequency or air volume that matches the original operating state of the main fan.

9. The method for controlling the combustion fan of a metallurgical heating furnace according to claim 8, characterized in that, The bearing fault characteristic frequency includes at least one of the following: bearing outer ring fault frequency BPFO, inner ring fault frequency BPFI, rolling element fault frequency BSF, and cage fault frequency FTF; the energy ratio is the ratio of the energy in the frequency band corresponding to the characteristic frequency to the total energy of the entire frequency band.

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