A method for controlling the operation of a hot-rolled multi-mode dust removal fan

Abstract

This invention discloses a multi-mode dust removal fan operation control method for hot rolling mills. From the descaling to the finishing rolling and steel-throwing process in the hot rolling production line, it establishes dust removal fan operation modes based on actual working conditions, combined with on-site detection signals. Specifically, this involves establishing adaptive control for maintenance operation, roll changing operation, and normal rolling operation under maintenance, roll changing, and normal rolling conditions. This multi-mode dust removal fan operation control method for hot rolling mills is designed with energy consumption reduction as its core technical focus and reliable operation as its technical support. It forms a multi-dimensional and multi-layered optimization scheme that considers the selection of frequency converter types, how to reliably establish operation, and how energy consumption reduction is reflected in every control link. This ensures that the frequency converter's operating frequency is always matched with the production conditions, thereby achieving better dust removal and energy-saving effects.

Description

Technical Field

[0001] This invention belongs to the field of automatic control in metallurgical steel rolling, and specifically relates to a method for controlling the operation of a multi-mode dust removal fan in hot rolling. Background Technology

[0002] Dust removal systems on existing hot rolling production lines typically operate dust collector fans at their rated speeds. Even with variable air volume (VAV) systems adapted to real-time conditions, the VAV is either adjusted by changing the damper opening while maintaining the rated speed, or theoretically, by using variable frequency drive (VFD) control for real-time VAV adjustment. However, the former method of maintaining the rated speed while adjusting the damper opening results in significant energy waste. The latter, based on the theoretically proposed real-time VFD method, poses risks of overcurrent or overvoltage in practical use, accelerating equipment aging and increasing costs, while also complicating setup and control. Therefore, achieving energy reduction simply, while maintaining equipment lifespan and without excessively increasing control or equipment complexity, presents a problem requiring technological optimization and solutions.

[0003] Chinese patent application CN1197118A discloses a "Fuzzy Control-Based Fully Automatic Dust Removal System," comprising a fan, dust removal accessories, an industrial control computer, and a variable frequency drive. This system utilizes fuzzy control theory and, through the industrial control computer, forms a closed-loop control system that automatically tracks and sets desired values ​​in real time. This invention automatically tracks the dust concentration during blast furnace tapping and controls the ventilation volume based on the dust concentration. The dust removal system stops operating during blast furnace ironmaking, thereby minimizing motor energy consumption, extending motor lifespan, and achieving excellent dust removal results.

[0004] The invention application with application number CN201810139919 7 discloses "a dust removal fan time period control system and a method for modifying a dust removal system", which includes: a human-machine interaction device connected to an intelligent speed regulation device for setting the production time period division time point and the corresponding gas negative pressure level value D in the intelligent speed regulation device; a gas pressure detection device installed in the dust collection pipeline to collect the actual gas negative pressure value P in the dust collection pipeline in real time and transmit it to the intelligent speed regulation device; and an intelligent speed regulation device connected to the dust removal fan, which, after determining the production time period of the dust removal system, compares the actual gas negative pressure value P and the gas negative pressure level value D, and adjusts the speed of the dust removal fan according to the comparison result and the worst-case principle to make P equal to D.

[0005] The invention application with application number CN201910698294.2 discloses "a dust removal method and device based on hot rolling process". The method can determine the first dust concentration value and the first difference between the second dust concentration at the flue baffle when the hot rolling four-high mill is rolling the current rolled material. When the first difference reaches a set threshold and the hot rolling four-high mill has completed rolling the current rolled material, before the hot rolling four-high mill rolls the next rolled material, the flue baffle is controlled to move from the initial position to the set position. Then, the cleaning equipment is controlled to clean the flue baffle and acquire the target image. When the target image reaches the cleaning standard, the flue baffle is controlled to move from the set position to the initial position. Summary of the Invention

[0006] The purpose of this invention is to provide a hot rolling dust removal method that reduces energy consumption without reducing the service life of equipment.

[0007] To achieve the above technical objectives, this invention provides a method for controlling the operation of a hot-rolled multi-mode dust removal fan, the specific technical solution of which is as follows:

[0008] A method for controlling the operation of a hot-rolled multi-mode dust removal fan.

[0009] From the descaling to the finishing rolling and steel-throwing process of the hot rolling production line, a dust removal fan operation mode is established based on the actual working conditions, combined with on-site detection signals.

[0010] The aforementioned establishment of dust collector fan operation modes based on actual working conditions specifically refers to:

[0011] Establish adaptive control systems for dust removal fans under maintenance conditions, roll changing conditions, and normal rolling conditions, respectively.

[0012] Furthermore,

[0013] This dust removal control unit is designed to adapt to the maintenance, roll changing, and normal rolling operations of dust removal fans, and is independent of the process control unit and the basic automation control unit.

[0014] The dust removal control unit can communicate with the process control unit;

[0015] or

[0016] A dust removal control unit is added to the basic automated control machine. The dust removal control unit is used to establish adaptive control for the maintenance operation of the dust removal fan, the roll changing operation, and the normal rolling operation.

[0017] Furthermore,

[0018] When under maintenance, the dust removal fan is shut down by the dust removal control machine or dust removal control unit.

[0019] When the roller changing operation is under the condition, the dust removal control machine or dust removal control unit shall control the status of the dust removal fan according to the current roller changing time.

[0020] When in normal rolling conditions, the dust removal fan or dust removal control unit controls the dust removal fan status according to the on-site detection signals.

[0021] Furthermore,

[0022] When the machine is in the roll changing operation, the dust removal control machine or dust removal control unit will control the status of the dust removal fan according to the current roll changing time. Specifically:

[0023] When the roller changing time exceeds the set threshold, the dust removal fan will be stopped by the dust removal control machine or dust removal control unit.

[0024] Otherwise, the dust removal fan is kept in standby mode by the dust removal control machine or dust removal control unit.

[0025] Furthermore,

[0026] When changing rolls for the first stand of the roughing mill, the judgment and control are directly based on the roll change exceeding the set threshold.

[0027] When changing rolls on the second stand of the roughing mill, the judgment and control are directly based on the fact that the roll change does not exceed the set threshold.

[0028] When changing rolls for the finishing mill stand, the roll changing time is recorded. If the roll changing time exceeds the set threshold, the dust removal control machine or dust removal control unit will control the dust removal fan to stop; otherwise, the dust removal control machine or dust removal control unit will control the dust removal fan to standby.

[0029] Furthermore,

[0030] Under normal rolling conditions, the dust removal fan or dust removal control unit controls the dust removal fan status according to the field detection signals, specifically:

[0031] When the dust removal control machine or dust removal control unit receives the descaling signal of the first strip steel, it controls the dust removal fan to maintain a constant low air volume in standby mode.

[0032] When the dust removal control machine or dust removal control unit receives a flying shear signal, a steel biting signal from the first stand of the finishing mill, a steel biting signal from the second stand of the finishing mill, or a steel biting signal from the third stand of the finishing mill, it uses one of these signals as a basis to control the dust removal fan to enter a frequency conversion control state based on the target air volume.

[0033] When the dust removal control machine or dust removal control unit receives the steel throwing signal from the last stand of the finishing mill, it controls the dust removal fan to enter standby mode.

[0034] Furthermore,

[0035] When the dust removal control machine or dust removal control unit receives the dephosphorization signal, it controls the dust removal fan to maintain a constant low airflow in standby mode. It also establishes a detection and judgment system based on the steel bite signal of the first stand of the roughing mill to determine whether the dust removal fan is maintaining a constant low airflow in standby mode. If the detection result is that the dust removal fan is maintaining a constant low airflow in standby mode, it returns to monitoring the flying shear signal. Otherwise, it issues a fault alarm and manually starts the dust removal fan to maintain a constant airflow in standby mode after troubleshooting.

[0036] Furthermore,

[0037] The detection and judgment of whether the dust removal fan is maintained in standby mode with a constant low air volume is established based on the bite signal of the first stand of the roughing mill. The determination is made by comprehensively considering the bite signal of the side press, the position sensor signal between the side press and the first stand of the roughing mill, and the bite signal of the first stand of the roughing mill.

[0038] When both the side press biting signal and the first stand of the roughing mill have a biting signal, and the position sensor signal between the side press and the first stand of the roughing mill is continuous, then the detection and judgment of whether the dust removal fan is maintained in standby state with a constant low air volume is established based on the biting signal of the first stand of the roughing mill; otherwise, the detection and judgment are not entered.

[0039] Furthermore,

[0040] When the side press has a steel biting signal and the position sensor signal between the side press and the first stand of the roughing mill is continuous, but the first stand of the roughing mill does not have a steel biting signal, the detection and judgment of whether the dust removal fan is maintained in standby state with a constant low air volume is established based on the position sensor signal.

[0041] Furthermore,

[0042] When controlling the dust removal fan to enter the frequency conversion control state based on the target air volume, the specific signal used is determined according to the frequency conversion speed, based on whether it is the flying shear signal, the bite signal of the first stand of the finishing mill, the bite signal of the second stand of the finishing mill, or the bite signal of the third stand of the finishing mill.

[0043] Furthermore,

[0044] When the position sensor signal is normal but the dust removal controller or dust removal control unit does not receive the flying shear signal, the dust removal fan is controlled to enter the frequency conversion control state based on the target air volume, according to the position sensor signal and the fine mill inlet temperature measuring instrument signal.

[0045] Furthermore,

[0046] When the dust removal control machine or dust removal control unit receives the steel throwing signal from the penultimate stand and / or the last stand of the finishing mill, it controls the dust removal fan to enter the shutdown state.

[0047] Furthermore,

[0048] The target air volume is determined based on the type of steel being rolled.

[0049] Furthermore,

[0050] If the dust removal control machine or dust removal control unit does not receive the steel discard signal from the last stand of the finishing mill within the set time,

[0051] or

[0052] If the steel discard signal from the penultimate stand and the last stand of the finishing mill are not received within the set time, the dust removal fan will be controlled to enter the shutdown state.

[0053] Furthermore,

[0054] The dust collector fan is driven by a variable frequency motor controlled by a vector frequency converter.

[0055] Furthermore,

[0056] The vector inverter is based on speed vector control.

[0057] This invention discloses a multi-mode dust removal fan operation control method for hot rolling mills. By establishing control of the dust removal fan based on actual operating conditions and incorporating on-site detection signals, it aims to achieve energy saving and consumption reduction. Compared to existing control methods that only determine whether the fan is stopped or operates at a constant airflow based on maintenance status, this method adds control strategies and fan operation modes, forming three operation modes: maintenance-adaptive control under maintenance conditions, roll-changing operation adaptive control under roll-changing conditions, and normal rolling operation adaptive control under normal rolling conditions. Under maintenance conditions, the dust removal fan is stopped; under roll-changing conditions, the dust removal fan is maintained in standby mode with a constant low airflow; under normal rolling conditions, the dust removal fan adapts to the target airflow and performs dust removal according to the type of steel being rolled. The standby mode under the roller changing condition formed by the above settings can reduce energy consumption on the one hand, and avoid the risk of overcurrent caused by sudden start-stop switching when dust removal is required on the other hand. It can smoothly transition to the dust removal condition, ensure the stability of dust removal operation, and thus benefit the dust removal quality and product quality.

[0058] The challenge in translating the above technological innovations into practical applications lies in establishing precise tracking and control. The applicant considered utilizing existing position sensor signals and temperature measuring instruments, but these signals are prone to loss or inaccuracy. The applicant further considered using bite signals installed at each process stage, but while these signals are theoretically more reliable, they cannot rule out the possibility of missed passes. Considering potential risks such as overcurrent during start-up and shutdown, the proposed control solution for normal rolling operation under normal rolling conditions involves running the fan at a constant low speed before the strip reaches the flying shear station. When the strip reaches the flying shear station, the fan frequency is adjusted to the target airflow. This avoids overcurrent during start-up and shutdown and effectively adapts to the frequency conversion time, ensuring good airflow adaptation upon reaching the target dust removal station. This further involves issues of signal reliability and control optimization. To address signal reliability and establish reliable control based on on-site detection signals, this technical solution uses the flying shear signal as the primary reference, supplemented by position sensors and temperature measuring instruments. Considering the stability of the frequency converter, it is set to operate at low speed before dust removal and continue to operate at low speed after strip polishing. Given the time required for frequency conversion transition, the frequency conversion timing is not based on the strip reaching the target stand, but rather on the strip reaching the flying shear station. The transition from dust removal to standby mode is based on the strip reaching the strip polishing position on the last stand of the finishing mill. Control optimization is achieved through the following settings: to allow time for inspection and correction in case of accidents or malfunctions, the fan startup is not based on the strip reaching a certain position before the flying shear, but rather on starting the fan and keeping it in standby mode when the strip reaches the descaling position. This allows time for subsequent fault inspection and troubleshooting, which is set when the strip reaches the first stand of the roughing mill. Meanwhile, considering that the bite signal of the first stand in the roughing mill may correspond to a strip that is not the target strip, a determination of whether the bite signal of the first stand in the roughing mill corresponds to the strip is established based on the side press signal and the position sensor signal. The position sensor can also serve as a substitute when the first stand in the roughing mill is missing. Correspondingly, the flying shear signal mentioned above can also be replaced by a position sensor when it is missing. Furthermore, since the flying shear signal is not a fixed position point, the frequency conversion time point can be considered based on the actual frequency conversion speed, using the first stand in the finishing mill, or the second stand in the finishing mill, or the third stand in the finishing mill. The setting principle and purpose are: to ensure a smooth transition so that when the strip reaches the dust removal target position, the corresponding dust removal airflow is also converted to the target airflow.

[0059] Some of the edge-care optimizations mentioned above include: to prevent problems with the steel ejection signal on the last stand of the finishing mill, the control optimization is combined with the steel ejection signal of the F6 stand; for example, when a fault occurs, the finishing mill will not eject steel, and the fan needs to be stopped. For example, in roll changing operations, to further reduce energy consumption, the roll changing time of each roll is monitored and tracked, and fan adaptation control is established based on the specific roll changing time.

[0060] In summary, the hot-rolled multi-mode dust removal fan operation control method of the present invention is designed with energy consumption reduction as its core technology and reliable operation as its technical support. It forms a multi-dimensional and multi-level optimized technical solution that considers the selection of frequency converter type, how to reliably establish operation of control, and the reduction of energy consumption in every control link. This ensures that the frequency converter operating frequency is always matched with the production conditions, thereby achieving better dust removal and energy saving effects. Attached Figure Description

[0061] Figure 1 This is a schematic diagram of the control flow of the present invention;

[0062] Figure 2 This is a flowchart illustrating the working principle and process of the present invention;

[0063] Figure 3 This is a schematic diagram of the hot rolling process in this invention. Detailed Implementation

[0064] The following is a further detailed description of the operation control method for a hot-rolled multi-mode dust removal fan according to the present invention, based on the accompanying drawings and specific embodiments.

[0065] To better understand this technical solution, its working principle and process are described below:

[0066] Before proceeding, let me first introduce the surrounding context.

[0067] Hot rolling production line section:

[0068] like Figure 3The diagram shows a complete hot rolling production line. After exiting the heating furnace, the strip steel reaches the descaling equipment (the HSB signal mentioned in the text is the descaling signal) to remove iron oxide scale, etc., and then reaches the side press (the SSP signal mentioned in the text is the side press bite signal) to enter the roughing rolling section. In the roughing rolling section, the first roughing mill stand R1 and the second roughing mill stand R2 are set sequentially, and then the flying shear (the CS mentioned in the text is the flying shear) is placed in front, and then it reaches the finishing rolling section. A finishing mill inlet temperature measuring instrument FET is also installed at the finishing mill inlet, and a finishing mill vertical roller FIE is also installed before the first finishing mill stand F1. The finishing rolling section usually has seven stands F1 to F7, and the dust removal section only applies to four stands F4 to F7. From descaling to the steel-throwing process after finishing rolling, position sensors are used to track the position of each strip steel, and temperature measuring instruments are also installed to perform corresponding temperature tests.

[0069] Communication part:

[0070] Basic communication involves the process controller and the basic automation controller. The basic automation controller is directed to each mechanical actuator and signal acquisition end. It is used to upload the acquired signals to the process controller for calculation and processing, and at the same time, it receives various control commands from the process controller and sends them to the corresponding mechanical actuators.

[0071] This technical solution involves dust removal control, which can be set up independently of the existing process control machine and basic automation control machine to form an independent dust removal control machine. Then, by establishing communication with the process control machine, corresponding control can be established based on the existing detection signals; alternatively, dust removal control can be formed by adding functional modules based on the existing basic automation control machine.

[0072] Variable frequency drive (VFD) section:

[0073] Existing frequency conversion technologies include V / F control, vector control, and direct torque control. Considering the smoothness and stability of control, as well as factors such as low-frequency torque, mechanical characteristics, and dynamic performance, this technical solution adopts vector frequency conversion to control the dust removal airflow, and further selects vector control with a speed sensor; a variable frequency motor is selected as the motor to well respond to the low-frequency operation required in the technical solution.

[0074] The advantages of using a vector frequency converter are as follows:

[0075] 1. High torque at low frequencies. Even when operating at 1Hz (or 0.5Hz), it can generate sufficient torque without the magnetic circuit saturation phenomenon that is easily encountered in U / f control mode.

[0076] 2. Good mechanical characteristics. It has relatively stiff mechanical characteristics throughout the entire frequency adjustment range, and all mechanical characteristics are basically parallel.

[0077] 3. Excellent dynamic response. Especially for vector control methods with speed feedback, the dynamic response time is generally less than 100ms.

[0078] Meanwhile, to fully leverage the advantages of vector control—high torque, good mechanical characteristics, and excellent dynamic response at lower frequencies—while avoiding the minor flaws of soft mechanical characteristics, low system torque, and poor state stability at extremely low frequencies, this technical solution sets the dust removal standby state at 10% of the rated frequency. This means that 10% of the rated frequency is used as the threshold for switching vector control on, truly achieving control that maximizes strengths and minimizes weaknesses. This fully utilizes the advantages of vector control—good adjustability, high stability, and low energy consumption.

[0079] The working principle and process can be understood in conjunction with the following: Figure 1 , Figure 2 conduct:

[0080] To achieve energy conservation and consumption reduction, this technical solution first optimizes the original start-stop system, implementing three operating modes: maintenance operation adaptation control under maintenance conditions, roll changing operation adaptation control under roll changing conditions, and normal rolling operation adaptation control under normal rolling conditions. Figure 2 The operating modes, roll changing modes, and maintenance modes are specified.

[0081] This optimized setup achieves the first level of energy saving and consumption reduction, primarily through the addition of a roll-changing mode. Previously, dust control only had two operating states: either a shutdown state during maintenance or a continuous operation state with constant airflow during non-maintenance conditions. With the addition of the roll-changing mode, energy saving and consumption reduction are achieved by setting the fan to maintain a low airflow in standby mode. Simultaneously, this setup provides a smooth transition step for establishing the corresponding target dust control after roll changing and before normal rolling, avoiding potential risks from factors such as overcurrent during motor start-up and shutdown, ensuring stable control. In roll changing mode, considering the varying roll changing times for different rolls, further optimizations aimed at energy saving and consumption reduction were implemented. This involved a direct shutdown control for R1 roll changing due to its longer time; standby control for R2 roll changing; and for roll changing on the finishing mill stand, the time was determined based on the specific roll changing duration. If the roll changing time exceeded the set time, a shutdown control was implemented; otherwise, standby control was used. Figure 2 As shown, the duration set here is approximately 20 minutes in this technical solution. However, the specific duration can be adjusted based on individual circumstances and factors.

[0082] The energy-saving and consumption-reducing aspects of the second dimension of this technical solution are reflected in the working mode. However, this is also where the difficulty of implementing this technical solution lies. The technical concept is as follows: to avoid the instability caused by motor overcurrent during start-up and shutdown, and because frequency conversion requires a transition time, a low-frequency standby state is first established before the target frequency is reached, based on the frequency conversion transition time. Then, based on the frequency conversion duration, a smooth transition is achieved so that the corresponding dust collection airflow reaches the target airflow when the strip reaches the dust collection target location. This determines the distance corresponding to this time before the target dust collection area. Obviously, this distance is related to the frequency conversion speed, so the specific location needs to be determined based on the specific frequency conversion speed. In the process of putting this technical concept into practice, the first problem encountered is determining the various target points. This technical solution uses a method combining on-site detection signals, but in actual implementation, control errors continue to occur due to the lack or inaccuracy of various signals. To further address these practical problems and ensure the effective implementation of the technical concepts, the applicant categorized the field detection signals into two main types: one is various bite and throw signals from the hot rolling production line, and the other is various position tracking signals (i.e., HMD signals) and temperature signals from thermometers (i.e., pyrometer signals). A control system based on field detection signals was established, using bite and throw signals as the foundation, supplemented by HMD and pyrometer signals for necessary replacement. Figure 1 As shown, this is specifically reflected in the correct start-up judgment and replacement scheme of R1 steel biting, the replacement scheme of flying shear signal (and the optimization scheme of flying shear signal based on frequency conversion speed here corresponds to the above purpose of "so that the corresponding dust removal air volume is also converted to the target air volume when the strip reaches the dust removal target position in a smooth transition"), and the optimization scheme of F7 frame steel throwing.

[0083] The basic controls based on the above-established working mode are as follows:

[0084] When the strip steel reaches the descaling station, the process control unit sends a signal indicating arrival at the descaling station to the dust removal control unit or dust removal control unit. Upon receiving the signal, the dust removal control unit starts the fan, which operates at a constant low speed in standby mode. When the strip steel reaches the flying shear position, the frequency converter is activated again based on the arrival signal. At this time, the fan, driven by the frequency converter motor, changes frequency from standby mode to the target air volume. According to the preset schedule, when the strip steel reaches the fourth stand of the finishing mill, the frequency conversion from low frequency to the target frequency is almost synchronously completed. Then, dust removal for the target process segment is performed according to the current target frequency until the last stand of the finishing mill issues a steel discard signal. At this point, the fan is controlled to change from the target frequency operating state back to a constant low speed in standby mode, waiting for the next strip steel. The specific value of the target air volume is determined according to the specific type of strip steel and is determined by the process requirements.

[0085] In the above basic control, to ensure that the fan is definitely running in standby mode when the strip reaches the flying shear position, a control based on the detection of the R1 biting position to determine if the fan has started normally is also established. Specifically:

[0086] When the dust control unit receives a bite signal from the first stand of the roughing mill from the process control unit, it determines whether the start-up is normal. If the detection result indicates a normal start-up, no action is taken, and the set control continues. If a normal start-up is detected, immediate troubleshooting is performed, and after troubleshooting, manual start-up is initiated via a set dry contact to restore normal standby operation. Due to the continuity of the preceding and following strips, there may be situations where the bite signal from the first stand of the roughing mill does not correspond to the target strip. Therefore, to avoid control errors caused by this problem, a correct start-up determination is established here. Specifically, it is determined by combining the bite signal from the side press, the position sensor signal between the side press and the first stand of the roughing mill, and the bite signal from the first stand of the roughing mill. When both the side press and the first stand of the roughing mill have bite signals, and the position sensor signals between the side press and the first stand of the roughing mill are continuous, the system proceeds to detect and determine whether the dust collector fan is maintaining a constant low airflow in standby mode based on the bite signal from the first stand of the roughing mill. Otherwise, the detection and determination process does not proceed. Simultaneously, a replacement scheme can be developed for when the bite signal is missing: when the side press has a bite signal and the position sensor signals between the side press and the first stand of the roughing mill are continuous, but the first stand of the roughing mill does not have a bite signal, the system proceeds to detect and determine whether the dust collector fan is maintaining a constant low airflow in standby mode based on the position sensor signals.

[0087] Based on the various optimizations established at each stage, the final optimized control logic is as follows:

[0088] First, the control mode is switched according to the current operating conditions. When the current mode is maintenance mode, the fan is controlled to be in a stopped state.

[0089] When the current roll changing mode is in operation, the fan is first controlled to run at a constant low speed in standby mode. Then, further optimization control is performed based on the specific roll changing duration. When the current roll changing is R1 roll changing, the fan is directly stopped. When the current roll changing is R2 roll changing, the fan is directly controlled to run in standby mode. When the current roll changing is finishing mill stand roll changing, specific control is performed based on the specific roll changing duration. When the roll changing duration exceeds the set threshold, the fan is stopped; otherwise, the fan is controlled to run in standby mode.

[0090] When the current rolling operation mode is normal, the fan is started first according to the descaling signal. Then, at the first stand of the roughing mill, the start-up success is determined according to the bite signal of the first stand of the roughing mill. If the start-up is successful, the control continues. Otherwise, the manual check and manual direct start are established to return the control to the normal main control. This involves a process to establish a correct correspondence between the strip and the bite signal from the side press and the position sensor signal, as well as a replacement scheme when the bite signal is missing. Specifically: when both the side press bite signal and the bite signal from the first stand of the roughing mill are present, and the position sensor signal between the side press and the first stand of the roughing mill is continuous, the process proceeds to detect and determine whether the dust collector fan is maintaining a constant low airflow in standby mode based on the bite signal from the first stand of the roughing mill; otherwise, the detection and determination process does not proceed. When the side press has a bite signal and the position sensor signal between the side press and the first stand of the roughing mill is continuous, but the first stand of the roughing mill does not have a bite signal, the process proceeds to detect and determine whether the dust collector fan is maintaining a constant low airflow in standby mode based on the position sensor signal. When the strip reaches the flying shear position, the frequency converter is activated based on the CS on signal, causing the airflow to transition from the previous low airflow to the target airflow. When the CS signal is missing, a replacement scheme can be formed based on the established second type of signal. That is, when the position sensor signal is normal but the dust removal control machine or dust removal control unit does not receive the flying shear signal, the dust removal fan is controlled to enter the frequency conversion control state based on the target air volume, based on the position sensor signal and the temperature measurement signal at the finishing mill inlet. At the same time, the frequency conversion time point established based on the flying shear signal is not unique, because the basis for setting the frequency conversion based on the flying shear signal is to see if the current frequency conversion speed can ensure that when the strip at the flying shear position runs to the F3 stand, the corresponding air volume reaches the target air volume. That is, the internal setting is based on the frequency conversion speed to determine the frequency conversion time and frequency conversion position. Therefore, this position can be changed according to the specific frequency conversion speed. However, considering the control reliability, the temperature measurement signal at the finishing mill inlet, the bite signal of the first finishing mill stand, the bite signal of the second finishing mill stand, and the bite signal of the third finishing mill stand become alternative signals to adapt to the specific frequency conversion speed. Finally, when the last stand of the finishing mill issues the steel-discarding signal, considering the cyclical nature of rolling, the blower is switched to a low-speed standby state based on the steel-discarding signal. Then, when the second strip and subsequent strips pass through descaling, it is not necessary to establish a start-up determination based on the descaling signal; instead, the R1 signal is used directly to determine whether a normal start-up is possible. Similarly, for operational stability and to handle unexpected situations, an optimization scheme and a fault response control scheme have been established for the F7 steel-discarding section.To prevent problems with the steel ejection signal of the last stand in the finishing mill, an optimized control system is developed, based on the steel ejection signal of stand F6, to control the dust collector fan to stop when the dust collector control machine or dust collector control unit receives the steel ejection signal from the penultimate stand and / or the last stand in the finishing mill. Simultaneously, a control system is also developed to control the dust collector fan to stop if the dust collector control machine or dust collector control unit fails to receive the steel ejection signal from the last stand in the finishing mill within a set time, or if it fails to receive both the steel ejection signals from the penultimate stand and the last stand in the finishing mill within a set time.

[0091] To facilitate a quick understanding of the above explanation, a brief summary is provided below:

[0092] The system automatically adapts its control mode based on different production conditions of the main rolling line, and correspondingly controls the frequency converter in real time at different frequencies to achieve multi-mode control: maintenance mode, roll changing mode, and operating mode. Simultaneously, the dust removal system automatically matches the fan status with the rolling line equipment status, i.e., stop mode, standby mode, vector control mode, and abnormal mode. The frequency converter's operating frequency is constantly matched with the production conditions to achieve the best dust removal and energy-saving effects.

[0093] In the dust removal system, the fan status and corresponding fan frequency can be preset. Taking the production line involved in this technical solution as an example, the specific correspondence between fan status and operating frequency is shown in the table below:

[0094]

[0095]

[0096] Standby: below 10%; Vector control: 10%-100%.

[0097] Dust collector fan mode selection

[0098] To enable the dust removal system to operate under different conditions on the rolling line, the system can be manually or automatically selected to select the appropriate control mode, namely maintenance mode, roll changing mode, and working mode. The dust removal system should be run in advance before the rolling line starts rolling. The L1 and L2 systems need to be optimized for relevant tracking and calculations, and the necessary operating data should be set for the dust removal system.

[0099] Based on the current rolling line status, namely maintenance mode, roll changing mode, and working mode.

[0100] The dust removal system PLC sends feedback to the basic automation L1 to set multiple digital input (DI) contacts, i.e.

[0101] (1) Dust removal fan control mode: automatic / manual;

[0102] (2) Dust removal control system operating status: running / stopped;

[0103] (3) Status of dust collector fan body, transmission device and PLC: Normal / Fault;

[0104] (4) Variable frequency control and vector control of dust collector fan:

[0105] To enable the 1880 dust removal system to operate under different conditions on the rolling line, namely maintenance mode, roll changing mode, and working mode, the following table shows the current HMD and pyrometer signal statuses involved in the hot rolling line:

[0106]

[0107] The table above can be used to calculate whether the equipment in the roughing or finishing mill area is currently in maintenance mode, roll changing mode, or working mode.

[0108] Maintenance mode

[0109] The status of the dust removal equipment is displayed on the HMI (dust removal) screen of the main finishing mill line (red for stop, green for run, yellow for fault). At the same time, the above status is displayed on the HMI screen of the finishing mill oil depot. When the maintenance mode button is selected during plant-wide scheduled maintenance or long-term shutdown, the dust removal fan enters the shutdown state.

[0110] Roll changing mode

[0111] The L2 server sends roll changing status information to the dust removal system, guiding the dust removal system to enter roll changing mode.

[0112] When the dust removal system receives a roller change message from the server, it generates a ROLL_STATUS event and performs corresponding processing. The ROLL_STATUS event is defined as follows:

[0113]

[0114] FmRollchangeLongTime is issued by the dust removal setting program, while other roller changing states are issued by the L2 receiving program.

[0115] Depending on the roller change time, the dust removal fan adopts two states: standby and stop. Taking the 1880 production line as an example, the stop state is adopted when the roller change time exceeds 20 minutes.

[0116] The status of the L2 blower during roll changing at the rolling mill is as follows:

[0117] When R1 changes rollers, the fan is sent to a shutdown state.

[0118] When R2 changes rollers, the fan is in standby mode.

[0119] When FM rolls are changed, the fan is sent to standby mode;

[0120] If the FM roll change continues for 20 minutes without rolling steel, the sending blower will be shut down.

[0121] Work mode

[0122] After the L2 server sends the working status information to the dust removal system, the fan enters standby mode. When the strip reaches R1 (R1 ON), the fan status is checked. If the fan still has not started, an abnormal alarm message is sent to L1. When the strip reaches the flying shear (CS ON), the fan enters vector control mode. After the strip is thrown (F7 OFF), the fan enters standby mode.

[0123] To prevent signal loss due to abnormal conditions such as scrap steel, if L1 does not receive the F7 OFF signal within 120 seconds after receiving CS ON, it will send an abnormal alarm and switch to standby mode.

Claims

1. A method for controlling the operation of a hot-rolled multi-mode dust removal fan, characterized in that: From the descaling to the finishing rolling and steel-throwing process of the hot rolling production line, a dust removal fan operation mode is established based on the actual working conditions, combined with on-site detection signals. The aforementioned establishment of dust collector fan operation modes based on actual working conditions specifically refers to: Establish adaptive control systems for dust removal fans under maintenance conditions, roll changing conditions, and normal rolling conditions, respectively; This dust removal control unit is designed to adapt to the maintenance, roll changing, and normal rolling operations of dust removal fans, and is independent of the process control unit and the basic automation control unit. The dust removal control unit can communicate with the process control unit; or A dust removal control unit is added to the basic automated control machine. The dust removal control unit is used to establish control for the maintenance operation of the dust removal fan, the roll changing operation, and the normal rolling operation. When under maintenance, the dust removal fan is shut down by the dust removal control machine or dust removal control unit. When the roller changing operation is under the condition, the dust removal control machine or dust removal control unit shall control the status of the dust removal fan according to the current roller changing time. When in normal rolling conditions, the dust removal control machine or dust removal control unit controls the status of the dust removal fan according to the on-site detection signals. Under normal rolling conditions, the dust removal control machine or dust removal control unit controls the dust removal fan status according to the field detection signals, specifically: When the dust removal control machine or dust removal control unit receives the descaling signal of the first strip steel, it controls the dust removal fan to maintain a constant low air volume in standby mode. When the dust removal control machine or dust removal control unit receives a flying shear signal, a steel biting signal from the first stand of the finishing mill, a steel biting signal from the second stand of the finishing mill, or a steel biting signal from the third stand of the finishing mill, it uses one of these signals as a basis to control the dust removal fan to enter a frequency conversion control state based on the target air volume. When the dust removal control machine or dust removal control unit receives the steel throwing signal from the last stand of the finishing mill, it controls the dust removal fan to enter standby mode.

2. The method for controlling the operation of a hot-rolled multi-mode dust removal fan according to claim 1, characterized in that: When the machine is in the roll changing operation, the dust removal control machine or dust removal control unit will control the status of the dust removal fan according to the current roll changing time. Specifically: When the roller changing time exceeds the set threshold, the dust removal fan will be stopped by the dust removal control machine or dust removal control unit. Otherwise, the dust removal fan is kept in standby mode by the dust removal control machine or dust removal control unit.

3. The method for controlling the operation of a hot-rolled multi-mode dust removal fan according to claim 2, characterized in that: When changing rolls for the first stand of the roughing mill, the judgment and control are directly based on the roll change exceeding the set threshold. When changing rolls on the second stand of the roughing mill, the judgment and control are directly based on the fact that the roll change does not exceed the set threshold. When changing rolls for the finishing mill stand, the roll changing time is recorded. If the roll changing time exceeds the set threshold, the dust removal control machine or dust removal control unit will control the dust removal fan to stop; otherwise, the dust removal control machine or dust removal control unit will control the dust removal fan to standby.

4. The method for controlling the operation of a hot-rolled multi-mode dust removal fan according to claim 1, characterized in that: When the dust removal control machine or dust removal control unit receives the dephosphorization signal, it controls the dust removal fan to maintain a constant low airflow in standby mode. It also establishes a detection and judgment system based on the steel bite signal of the first stand of the roughing mill to determine whether the dust removal fan is maintaining a constant low airflow in standby mode. If the detection result is that the dust removal fan is maintaining a constant low airflow in standby mode, it returns to monitoring the flying shear signal. Otherwise, it issues a fault alarm and manually starts the dust removal fan to maintain a constant airflow in standby mode after troubleshooting.

5. The operation control method for a hot-rolled multi-mode dust removal fan according to claim 4, characterized in that: The detection and judgment of whether the dust removal fan is maintained in standby mode with a constant low air volume is established based on the bite signal of the first stand of the roughing mill. The determination is made by comprehensively considering the bite signal of the side press, the position sensor signal between the side press and the first stand of the roughing mill, and the bite signal of the first stand of the roughing mill. When both the side press biting signal and the first stand of the roughing mill have a biting signal, and the position sensor signal between the side press and the first stand of the roughing mill is continuous, then the detection and judgment of whether the dust removal fan is maintained in standby state with a constant low air volume is established based on the biting signal of the first stand of the roughing mill; otherwise, the detection and judgment are not entered.

6. The method for controlling the operation of a hot-rolled multi-mode dust removal fan according to claim 5, characterized in that: When the side press has a steel biting signal and the position sensor signal between the side press and the first stand of the roughing mill is continuous, but the first stand of the roughing mill does not have a steel biting signal, the detection and judgment of whether the dust removal fan is maintained in standby state with a constant low air volume is established based on the position sensor signal.

7. The method for controlling the operation of a hot-rolled multi-mode dust removal fan according to claim 1, characterized in that: When controlling the dust removal fan to enter the frequency conversion control state based on the target air volume, the specific signal used is determined according to the frequency conversion speed, based on whether it is the flying shear signal, the bite signal of the first stand of the finishing mill, the bite signal of the second stand of the finishing mill, or the bite signal of the third stand of the finishing mill.

8. The method for controlling the operation of a hot-rolled multi-mode dust removal fan according to claim 1, characterized in that: When the position sensor signal is normal but the dust removal controller or dust removal control unit does not receive the flying shear signal, the dust removal fan is controlled to enter the frequency conversion control state based on the target air volume, according to the position sensor signal and the fine mill inlet temperature measuring instrument signal.

9. The method for controlling the operation of a hot-rolled multi-mode dust removal fan according to claim 1, characterized in that: When the dust removal control machine or dust removal control unit receives the steel throwing signal from the penultimate stand and / or the last stand of the finishing mill, it controls the dust removal fan to enter the shutdown state.

10. The method for controlling the operation of a hot-rolled multi-mode dust removal fan according to claim 1, characterized in that: The target air volume is determined based on the type of steel being rolled.

11. A method for controlling the operation of a hot-rolled multi-mode dust removal fan according to claim 1 or 9, characterized in that: If the dust removal control machine or dust removal control unit does not receive the steel discard signal from the last stand of the finishing mill within the set time, or If the steel discard signal from the penultimate stand and the last stand of the finishing mill are not received within the set time, the dust removal fan will be controlled to enter the shutdown state.

12. The method for controlling the operation of a hot-rolled multi-mode dust removal fan according to claim 1, characterized in that: The dust collector fan is driven by a variable frequency motor controlled by a vector frequency converter.

13. The method for controlling the operation of a hot-rolled multi-mode dust removal fan according to claim 12, characterized in that: The vector inverter is based on speed vector control.

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