Control method of ultra-fast cooling system in hot continuous rolling production line

Abstract

A control method of an ultra-fast cooling system in a hot continuous rolling production line belongs to the technical field of metal rolling and comprises the following steps: a communication system acquires rolled piece data and transmits the rolled piece data to a process automation system, and a result is sent to a basic automation system after setting and calculation; the rolled piece is conveyed to a second rolling mill, the basic automation system sends related flow and pressure mode data to a pump station system, and a pump station determines frequency rising according to the condition of a water pump; the head of the strip steel reaches a third rolling mill and is in a dry head control mode, and the basic automation system calculates the compensation distance of front and rear ultrafast cooling system headers; from the head to the fifth rolling mill, a bypass regulating valve is arranged for initial opening degree, and pressure closed-loop control is started; from the head to a finish rolling outlet pyrometer, dynamic setting calculation is started, and pressure compensation of a front ultrafast cooling system is processed; then, according to different positions of the strip steel head on the front and rear ultrafast cooling systems, a bypass regulating valve is adjusted, and closed-loop control is switched; and after the tail part of the strip steel leaves each cooling area, reducing the frequency of the water pump and sequentially closing the front and rear ultrafast cooling system headers.

Description

Technical Field

[0001] The present application belongs to the technical field of metal rolling, and in particular relates to a control method for an ultra-fast cooling system in a hot rolling production line. Background Art

[0002] In the field of hot rolling production technology, ultra-fast cooling technology is the key technology to achieve the regulation of the microstructure and properties of hot-rolled strip steel.

[0003] In practical applications, in order to ensure the accuracy of temperature control of the strip during the entire cooling process, when the strip enters the cooling area of ​​the ultra-fast cooling system, the flow and pressure of the ultra-fast cooling system must be kept stable. However, due to special temperature control requirements at the head of the strip, such as the implementation of the dry head process. During the dry head process control process, it is easy to cause the pressure of the ultra-fast cooling system to fluctuate greatly. This pressure fluctuation not only destroys the originally set stable operating state of the system, but also causes a large deviation in the temperature control of the head, making it difficult to accurately execute the cooling process according to the predetermined process parameters, which greatly affects the stability and consistency of product quality.

[0004] Especially in the complex process layout of the production line using the front and rear ultra-fast cooling system, the coordinated work between the front and rear ultra-fast cooling systems and the stable control of their respective pressures have become huge challenges. Due to the different positions and functions of the front and rear systems in the strip cooling process, they are interrelated and influence each other. How to effectively coordinate the pressure changes of the front and rear ultra-fast cooling systems during the special process treatment of the strip head and the entire cooling process, achieve stable and reliable pressure control, and then ensure that the strip cooling process is smooth and smooth, has become a key problem that needs to be overcome in the industrial application of ultra-fast cooling systems in current hot rolling production. Summary of the invention

[0005] In view of this, the present application provides a control method for an ultra-fast cooling system in a hot rolling production line, the main purpose of which is to achieve flow and pressure stability of the ultra-fast cooling system, thereby ensuring the accuracy of strip temperature control.

[0006] In order to achieve the above objectives, this application mainly provides the following technical solutions: The present application provides a control method for an ultra-fast cooling system in a hot rolling production line, wherein the ultra-fast cooling system comprises an ultra-fast cooling device, a basic automation system, a process automation system and a communication system, and the control method comprises the following steps: Step 1: After the finishing rolling setting calculation is completed, the communication system collects the product data information of the rolled piece, the finishing rolling setting data and the real-time data of the rolling line, and transmits them to the process automation system. The process automation system completes the setting calculation of the strip cooling process based on the received data, and transmits the calculation results to the basic automation system; Step 2: When the rolled product arrives at the second rolling mill, the basic automation system transmits the single header flow, total flow and pressure mode in the set calculation results to the pump station system; Step 3: Determine the number of available water pumps. The pump station system determines the water pump frequency based on the water pump number-pressure-flow table and starts the frequency increase operation according to the frequency curve; Step 4: When the strip head reaches the third rolling mill and the strip head is in the dry head control mode, the basic automation system calculates the compensation distance of each header of the front and rear ultra-fast cooling systems according to the dry head length, strip speed, response time of the header opening and closing valve and cooling mode of the ultra-fast cooling system issued by the process automation system; Step 5: When the head of the strip arrives at the fifth rolling mill, the initial opening degree of the bypass regulating valves of the front and rear ultra-fast cooling systems is set, and the front ultra-fast cooling pressure closed-loop control is started; Step 6: When the strip head reaches the high temperature meter at the finishing exit: (1) Start the dynamic setting calculation of the strip cooling process, and dynamically adjust the opening state of the header in the cooling zone according to the measured cooling temperature, strip speed and target temperature of each section; (2) The investment in the closed-loop calculation of the pressure of the front ultra-fast cooling system is cancelled. The compensation value of the bypass regulating valve of the front ultra-fast cooling system for the pressure compensation of the strip head is calculated based on the total water volume set for the front ultra-fast cooling system issued by the process automation system and the actual water volume fed back by the pump station system. The compensation slope of the bypass regulating valve of the front ultra-fast cooling system is calculated based on the speed of the final stand of the finishing rolling mill and the length of the cooling area of ​​the front ultra-fast cooling system. Step 7: When the head of the strip is in the cooling area of ​​the front ultra-fast cooling system, the bypass regulating valve of the front ultra-fast cooling system is adjusted according to the calculated compensation slope; after the head of the strip leaves the cooling area of ​​the front ultra-fast cooling system, the front ultra-fast cooling system is put into pressure closed-loop calculation and header flow closed-loop calculation; Step 8: When the head of the strip reaches the laminar cooling fine adjustment section, the basic automation system calculates the compensation value of the bypass regulating valve of the post-ultra-fast cooling system for the pressure compensation of the head of the strip according to the total water volume set by the post-ultra-fast cooling system issued by the process automation system and the actual water volume fed back by the pump station system, and calculates the compensation slope of the bypass regulating valve of the post-ultra-fast cooling system according to the speed of the final stand of the finishing rolling mill and the length of the cooling area of ​​the post-ultra-fast cooling system; when the head of the strip reaches the first header of the post-ultra-fast cooling system, the input of the closed-loop calculation of the pressure of the front ultra-fast cooling system and the closed-loop calculation of the header flow are cancelled; Step 9: When the head of the strip is in the cooling area of ​​the rear ultra-fast cooling system, the bypass regulating valve of the rear ultra-fast cooling system is adjusted according to the calculated compensation slope; when the head of the strip leaves the cooling area of ​​the rear ultra-fast cooling system, the pressure closed-loop calculation and the manifold flow closed-loop calculation of the front and rear ultra-fast cooling systems are put into operation; Step 10: When the tail of the strip leaves the cooling area of ​​the front ultra-fast cooling system, the pump station system receives the water consumption of the rear ultra-fast cooling system sent by the basic automation system, determines the pump frequency, and starts to reduce the frequency according to the frequency reduction curve. After reducing to the first specific frequency, the front ultra-fast cooling system headers are closed in sequence; Step 11: When the tail of the strip leaves the cooling area of ​​the rear ultra-fast cooling system, the water pump frequency drops to the basic frequency. After it drops to the second specific frequency, the rear ultra-fast cooling system headers are closed in sequence.

[0007] Optionally, the ultra-fast cooling device includes multiple groups of front-type ultra-fast cooling and multiple groups of rear-type ultra-fast cooling, the front-type ultra-fast cooling is located between the finishing mill and the laminar cooling, and the rear-type ultra-fast cooling is located between the laminar fine adjustment manifold and the coiler.

[0008] Optionally, in step 4, the compensation distance of each of the headers meets the formula: ; In the formula, is the target stem length, m; is the strip threading speed, m / s; is the valve response time, s; The number of headers opened for the ultra-fast cooling system; It is the serial number of the opening header.

[0009] Optionally, in step six, the compensation value of the bypass regulating valve of the front ultra-fast cooling system complies with the formula: ; In the formula, The set total water volume of the front ultra-fast cooling system issued by the process automation system, m³ / h; The number of bypass regulating valves of the front ultra-fast cooling system; The number of bypass regulating valves of the post-mounted ultra-fast cooling system; The opening size of the bypass regulating valve of the pre-mounted ultra-fast cooling system is initially set; The opening degree of the bypass regulating valve of the post-mounted ultra-fast cooling system is initially set; The amount of water fed back after the pump station system is upgraded; It is the maximum discharge capacity of the sewage pipeline.

[0010] Optionally, in step six, the compensation slope of the bypass regulating valve of the front ultra-fast cooling system meets the formula: ; In the formula, is the compensation value of the bypass regulating valve of the front ultra-fast cooling system, is the strip threading speed, m / s; is the cooling area length of the front ultra-fast cooling system, m.

[0011] Optionally, in step eight, the compensation value of the bypass regulating valve of the post-ultra-fast cooling system complies with the formula: ; In the formula, The set total water volume of the post-ultra-fast cooling system issued by the process automation system, m³ / h; The number of bypass regulating valves of the front ultra-fast cooling system; The number of bypass regulating valves of the post-mounted ultra-fast cooling system; The opening size of the bypass regulating valve of the pre-stage ultra-fast cooling system when the system pressure is stabilized within the set pressure range after the pressure closed loop is calculated; The opening degree of the bypass regulating valve of the post-mounted ultra-fast cooling system is initially set; is the actual water volume of the front ultra-fast cooling system, m³ / h; The amount of water fed back after the pump station system is upgraded; It is the maximum discharge capacity of the sewage pipeline.

[0012] Optionally, in step eight, the compensation slope of the bypass regulating valve of the post-ultra-fast cooling system complies with the formula: ; In the formula, is the compensation value of the bypass regulating valve of the post-super-fast cooling system, is the strip threading speed, m / s; is the cooling area length of the post-ultra-fast cooling system, m.

[0013] By means of the above technical solution, the present application has at least the following beneficial effects: The control method of the ultra-fast cooling system in the hot rolling production line provided in the embodiment of the present application can estimate and compensate for the possible pressure changes in advance by calculating the compensation distance of each header of the front and rear ultra-fast cooling systems, reduce the impact of the dry head process on the pressure stability of the entire ultra-fast cooling system, and enable the ultra-fast cooling system to maintain a relatively stable pressure environment when the head of the strip enters the cooling area. At the same time, the front and rear ultra-fast cooling pressure closed-loop control is opened and cancelled in a timely manner. When the head of the strip is in different cooling areas, such as the cooling area of ​​the front and rear ultra-fast cooling systems, the pressure fluctuations caused by factors such as the change in strip speed, the opening and closing of the header, and the connection between different cooling areas are effectively balanced through the precise adjustment of the bypass regulating valve and the reasonable switching of the pressure closed-loop control, ensuring the stability of the pressure during the entire cooling process, avoiding the impact of unstable pressure on the pipes, valves and other equipment of the ultra-fast cooling device, and extending the service life of the equipment. At the same time, it also ensures the stable and smooth cooling process, and improves product quality and production efficiency.

[0014] Furthermore, starting from the end of the finishing rolling setting calculation, through the coordinated data collection and calculation transmission of the communication system, process automation system and basic automation system, the single header flow and total flow setting values ​​are accurately determined based on various data of the rolled piece, and transmitted to the pump station system. The pump station system determines the appropriate pump frequency based on the accurate pump number-pressure-flow table and increases the frequency operation, providing a basic guarantee for stable flow, so that the entire cooling process can accurately allocate the flow according to the set requirements, avoiding uneven cooling and product quality problems caused by flow fluctuations. At the same time, at different stages of the head and tail of the strip, through the reasonable control of the bypass regulating valves of the front and rear ultra-fast cooling systems, such as calculating the compensation value and compensation slope based on the difference between the set total water volume and the actual water volume, and dynamically adjusting the bypass regulating valve, effectively compensate for the flow changes caused by various factors, such as special processes at the head and switching of the cooling area at the tail, ensuring that the flow is always in a relatively stable state during the entire strip cooling process, thereby ensuring the consistency of the cooling effect and the stability of product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A flow chart of a control method of an optional embodiment of the present application; Figure 2 This is a pressure control curve diagram for a conventional ultra-fast cooling system; Figure 3 For application Figure 1 The pressure control curve diagram of the ultra-fast cooling system of the control method shown; Figure 4 For application Figure 1 Temperature control curve diagram of the ultra-fast cooling system of the control method shown. DETAILED DESCRIPTION

[0016] The exemplary embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0017] See also Figure 1 As shown, an embodiment of the present application provides a control method for an ultra-fast cooling system in a hot rolling production line, wherein the ultra-fast cooling system includes an ultra-fast cooling device, a basic automation system, a process automation system and a communication system.

[0018] Among them, the ultra-fast cooling device can be composed of an ultra-fast cooling header for cooling the strip. The basic automation system is used to receive instructions from the upper system, such as the process automation system, and convert these instructions into specific equipment operation signals to control the operation of the ultra-fast cooling device and related auxiliary equipment, such as water pumps, valves, etc. The process automation system has built-in mathematical models and algorithms for setting calculations for the strip cooling process. For example, according to the material of the strip and the performance requirements of the final product, the target temperature to be achieved in different cooling stages and the cooling parameters such as the cooling medium flow rate and the header opening state required to achieve these target temperatures are calculated. Then, these calculation results are sent to the basic automation system to guide it to perform specific operation control on the cooling device and other equipment. The communication system is used to connect the various components of the ultra-fast cooling system so that data can be continuously exchanged between the components. For example, the calculation results of the process automation system are transmitted to the basic automation system so that the basic automation system performs corresponding operations.

[0019] Specifically, in the hot rolling production line, the ultra-fast cooling device has multiple groups of front-end ultra-fast cooling and multiple groups of rear-end ultra-fast cooling. The front-end ultra-fast cooling is located between the finishing mill and the laminar cooling. The finishing mill is the key equipment for the final shape rolling of the strip, so that the strip is still at a high temperature after leaving the finishing mill. At this time, the front-end ultra-fast cooling intervenes quickly, and the temperature of the strip is quickly reduced by ultra-fast cooling, thereby refining the grain structure. The rear-end ultra-fast cooling is located between the laminar fine adjustment manifold and the coiler. The rear-end ultra-fast cooling is used to start the second stage of cooling of the strip after the front-end ultra-fast cooling. The rear-end ultra-fast cooling can quickly cool the strip to the target coiling temperature by accurately controlling the cooling speed. With the help of the coordinated cooperation of the front and rear ultra-fast cooling, the temperature change of the strip can be fully and accurately controlled in the cooling link from finishing rolling to coiling in the hot rolling production line, thereby achieving the toughening of steel products.

[0020] The control method comprises the following steps: Step 1: After the finishing setting calculation is completed, the communication system collects the product data information of the rolled piece, the finishing setting data and the real-time data of the rolling line, and transmits them to the process automation system. The process automation system completes the setting calculation of the strip cooling process based on the received data and transmits the calculation results to the basic automation system.

[0021] In this embodiment, when the rolling line update calculation is completed, it means that in the hot rolling production line, some basic parameters related to the rolled product have been calculated. At this time, the communication system begins to play a role, and the communication system will collect data from various aspects. The product data information of the rolled product includes the material information and specification information of the strip steel. The specification information may include thickness information and width information, etc. These data determine the basic requirements of the subsequent cooling process, because strip steels of different materials and specifications require different cooling strategies to achieve ideal performance. The finishing setting data covers various setting parameters of the finishing mill, such as the target final rolling temperature and rolling speed of the finishing mill. These parameters are closely related to the state of the strip steel after finishing rolling and will affect the starting conditions of the cooling process. The real-time data of the rolling line reflects the actual operating state of the current rolling line, such as the actual temperature of the strip steel, the running speed of the strip steel and other dynamic information. After collecting all these data, the communication system transmits them to the process automation system. The process automation system uses the temperature model, heat exchange model and setting model according to the received data to complete the setting calculation of the strip steel cooling process. This calculation process will determine key parameters such as the amount of water required for cooling and the cooling temperature settings for different areas. Finally, these calculation results will be transmitted to the basic automation system to provide a basis for subsequent actual control operations.

[0022] Step 2: When the rolled product arrives at the second rolling mill, the basic automation system transmits the single header flow, total flow and pressure mode in the set calculation results to the pump station system.

[0023] In this embodiment, when the rolled piece arrives at the second rolling mill, the rolled piece completes the final finishing setting calculation. The process automation system receives the updated calculated data, updates the setting calculation of the cooling process accordingly, and sends the calculation results to the basic automation system. The basic automation system extracts key information such as single header flow, total flow and pressure mode from the calculation results and transmits them to the pump station system. The single header flow determines the flow size of the cooling medium, such as water, in each cooling header, the total flow is the overall water flow requirement of the entire ultra-fast cooling system, and the pressure mode specifies the pressure state that the system should maintain. The pump station system needs this information to prepare to provide a suitable cooling medium supply. For example, if the single header flow is set to 100m³ / h, the total flow is 4000m³ / h, and the pressure mode is high pressure mode, the basic automation control system sends this information to the pump station system so that the pump station system is prepared to provide cooling medium according to such flow and pressure requirements.

[0024] Step 3: Determine the number of available water pumps. The pump station system determines the water pump frequency based on the water pump number-pressure-flow table and starts the frequency increase operation according to the frequency curve.

[0025] In this embodiment, the number of available water pumps must be determined first, because the number of water pumps in the pump station system may change due to operating modes, equipment maintenance, and other reasons. After determining the number of available water pumps, the water pump frequency is determined based on the water pump number-pressure-flow table. This table is obtained through calibration and continuous optimization in the actual production process. It clarifies the frequency at which the water pump should run to achieve a specific pressure and flow under different combinations of water pump numbers. After determining the frequency, the frequency increase operation is started according to the frequency curve. The frequency curve is usually designed based on the performance characteristics and process requirements of the equipment. The frequency curve specifies the frequency change law over time from the start of the water pump to the target frequency. Through this frequency increase operation, the water pump gradually increases the speed, thereby steadily increasing the water pressure and water volume to a level that meets the initial requirements of the cooling system. For example, if it is determined that there are five water pumps available, by looking up the table, it is found that to achieve the set flow and pressure, the water pump frequency needs to be increased from 20Hz to 35Hz, then the water pump frequency is increased according to the frequency increase curve.

[0026] Step 4: When the strip head reaches the third rolling mill and is in the dry head control mode, the basic automation system calculates the compensation distance of each header of the front and rear ultra-fast cooling systems according to the dry head length, strip speed, response time of the header opening and closing valve and cooling mode of the ultra-fast cooling system issued by the process automation system.

[0027] In this embodiment, when the head of the strip arrives at the third rolling mill and is in the dry head control mode, the strip head has a special situation when it just enters the cooling area, which is different from the cooling requirements of the subsequent main part of the strip. The basic automation system calculates the compensation distance of each header of the front and rear ultra-fast cooling systems according to the parameters such as the dry head length, strip speed, response time of the header opening and closing valve, and cooling mode of the ultra-fast cooling system issued by the process automation system. The dry head length determines the range of the strip head that requires special treatment, the strip speed affects the speed of heat exchange, the cooling time, and the control accuracy of the dry head, the response time of the header opening and closing valve is related to the timeliness and accuracy of the cooling control, and the cooling mode specifies the overall cooling strategy framework. The compensation distance is calculated by combining these factors, the purpose is to adjust the opening state or flow distribution of the header in advance to compensate for the uneven cooling or pressure fluctuations that may be caused by the special situation of the dry head, to ensure that when the strip head enters the formal cooling area, the entire ultra-fast cooling system can smoothly transition to a normal cooling state, and avoid drastic fluctuations in system pressure and flow caused by dry head problems. For example, if the dry head length is 3m, the strip speed is 5m / s, the header opening and closing valve response time is 0.1s, and the cooling mode is segmented cooling, it can be determined by calculation how long each header needs to travel after the strip head to start cooling in this case, and this distance is the compensation distance.

[0028] Specifically, the compensation distance of each header complies with the formula: ; In the formula, is the target stem length, m; is the strip threading speed, m / s; is the valve response time, s; The number of headers opened for the ultra-fast cooling system; It is the serial number of the opening header.

[0029] Step 5: When the head of the strip arrives at the fifth rolling mill, set the initial opening degree of the bypass regulating valves of the front and rear ultra-fast cooling systems, and start the front ultra-fast cooling pressure closed-loop control.

[0030] In this embodiment, when the head of the strip arrives at the fifth rolling mill, it is closer to entering the cooling area, and further preparations need to be made for the cooling process that is about to begin. The initial opening of the bypass regulating valve of the front and rear ultra-fast cooling systems is set. The bypass regulating valve can adjust the flow distribution of the cooling medium and the pressure of the ultra-fast cooling system. By setting a suitable initial opening, a preliminary stable pressure and flow basic state can be established before cooling begins. At the same time, the front ultra-fast cooling pressure closed-loop control is turned on. The pressure closed-loop control is an automatic control method. The pressure value in the system is monitored in real time by a sensor, and compared with the set target pressure. The relevant equipment, such as the water pump speed, valve opening, etc., is automatically adjusted according to the difference, so that the system pressure is always maintained near the set value, so that the pressure can be quickly responded and stabilized when the strip enters the cooling area. For example, the initial opening of the bypass regulating valve is set to 30%, so that part of the cooling medium can pass through the bypass pipe and part of it can enter the cooling manifold. After the pressure closed-loop control is put into operation, if the actual pressure is higher than the set pressure, the system will automatically adjust the valve and other equipment to reduce the pressure.

[0031] Step 6: When the strip head reaches the high temperature meter at the finishing exit: (1) Start the dynamic setting calculation of the strip cooling process, and dynamically adjust the opening state of the header in the cooling zone according to the measured cooling temperature, strip speed and target temperature of each section; (2) The investment in the closed-loop calculation of the pressure of the pre-ultra-fast cooling system is eliminated. The compensation value of the bypass regulating valve of the pre-ultra-fast cooling system for the strip head pressure compensation is calculated based on the total water volume set for the pre-ultra-fast cooling system issued by the process automation system and the actual water volume fed back by the pump station system. The compensation slope of the bypass regulating valve of the pre-ultra-fast cooling system is calculated based on the speed of the final stand of the finishing rolling mill and the length of the cooling area of ​​the pre-ultra-fast cooling system.

[0032] In this embodiment, when the head of the strip reaches the high temperature at the finishing exit, this is a key starting point of the cooling process. The dynamic setting calculation of the strip cooling process is started because in actual production, although there is a setting calculation before, due to various practical factors, such as slight deviations of the equipment, the difference between the actual temperature of the rolled piece and the expected temperature, etc., it is necessary to dynamically adjust the opening state of the manifold in the cooling zone according to the measured opening temperature, that is, the temperature actually measured at the finishing exit of the strip, the strip speed and the target temperature of each section. For example, if the measured opening temperature is high, it may be necessary to increase the number of open manifolds or increase the manifold flow to speed up the cooling speed; if the strip speed becomes faster, it may be necessary to adjust the manifold layout and flow distribution accordingly to ensure that the strip can reach the target temperature of each section at the appropriate position; cancel the investment in the pressure closed-loop calculation of the front ultra-fast cooling system, because when the head of the strip just enters the cooling area, due to the special thermal state of the head and the connection problem with the subsequent strip, the previously opened pressure closed-loop control may cause unstable adjustment due to factors such as the instantaneous thermal shock of the head. At this time, the compensation value of the bypass regulating valve of the front ultra-fast cooling system for the pressure compensation of the strip head is calculated based on the total water volume set by the front ultra-fast cooling system issued by the process automation system and the actual water volume fed back by the pump station system. If there is a deviation between the set total water volume and the actual water volume, it is necessary to compensate through the bypass regulating valve, and the compensation slope of the bypass regulating valve of the front ultra-fast cooling system is calculated according to the speed of the final stand of the finishing rolling mill and the length of the cooling area of ​​the front ultra-fast cooling system. The compensation slope determines the adjustment rate of the bypass regulating valve when the strip head passes through the cooling area of ​​the front ultra-fast cooling system, so as to achieve smooth compensation and control of the pressure.

[0033] Specifically, the compensation value of the bypass regulating valve of the front ultra-fast cooling system conforms to the formula: ; In the formula, The total water volume set for the front ultra-fast cooling system issued by the process automation system, m³ / h; The number of bypass regulating valves of the front ultra-fast cooling system; The number of bypass regulating valves of the post-mounted ultra-fast cooling system; The opening size of the bypass regulating valve of the pre-mounted ultra-fast cooling system is initially set; The opening degree of the bypass regulating valve of the post-mounted ultra-fast cooling system is initially set; The amount of water fed back after the pump station system is upgraded; It is the maximum discharge capacity of the sewage pipeline.

[0034] The compensation slope of the bypass regulating valve of the front ultra-fast cooling system conforms to the formula: ; In the formula, is the compensation value of the bypass regulating valve of the front ultra-fast cooling system, is the strip threading speed, m / s; is the cooling area length of the front ultra-fast cooling system, m.

[0035] Step 7: When the strip head is in the cooling area of ​​the front ultra-fast cooling system, the bypass regulating valve of the front ultra-fast cooling system is adjusted according to the calculated compensation slope; after the strip head leaves the cooling area of ​​the front ultra-fast cooling system, the front ultra-fast cooling system is put into pressure closed-loop calculation and header flow closed-loop calculation.

[0036] In this embodiment, when the head of the steel strip is in the cooling area of ​​the front ultra-fast cooling system, the bypass regulating valve of the front ultra-fast cooling system is adjusted according to the compensation slope calculated previously. In this way, the flow distribution of the cooling medium is gradually adjusted to compensate for the pressure fluctuations caused by factors such as changes in the thermal state of the steel strip head and changes in the manifold flow, so that the pressure can remain relatively stable when the steel strip head passes through the cooling area of ​​the front ultra-fast cooling system. After the steel strip head leaves the cooling area of ​​the front ultra-fast cooling system, the pressure closed-loop calculation and the manifold flow closed-loop calculation of the front ultra-fast cooling system are put into operation. Because at this time the steel strip head has passed the initial special treatment stage and entered a relatively stable main cooling process, the pressure closed-loop calculation and the manifold flow closed-loop calculation can accurately adjust the system parameters automatically according to the difference between the set value and the actual monitoring value, ensuring that the entire front ultra-fast cooling system maintains stable pressure and flow during the cooling process of the main body of the steel strip.

[0037] Step 8: When the head of the strip reaches the laminar cooling fine-tuning section, the basic automation system calculates the compensation value of the bypass regulating valve of the post-ultra-fast cooling system for the pressure compensation of the strip head according to the total water volume set by the post-ultra-fast cooling system issued by the process automation system and the actual water volume fed back by the pump station system, and calculates the compensation slope of the bypass regulating valve of the post-ultra-fast cooling system according to the speed of the final rack of the finishing rolling mill and the length of the cooling area of ​​the post-ultra-fast cooling system; when the head of the strip reaches the first header of the post-ultra-fast cooling system, the input of the closed-loop calculation of the pressure of the front ultra-fast cooling system and the closed-loop calculation of the header flow are cancelled.

[0038] In this embodiment, when the head of the steel strip reaches the laminar cooling fine adjustment section, similar to the previous principle, the basic automation system calculates the compensation value of the bypass regulating valve of the post-ultra-fast cooling system for the pressure compensation of the steel strip head according to the total water volume set by the post-ultra-fast cooling system issued by the process automation system and the actual water volume fed back by the pump station system. Since the thermal state of the steel strip head and the cumulative effect of the previous cooling process will affect the pressure balance of the post-ultra-fast cooling system when it enters the post-ultra-fast cooling system, it is necessary to compensate by the bypass regulating valve. Then, according to the speed of the final rack of the finishing rolling mill and the length of the cooling area of ​​the post-ultra-fast cooling system, the compensation slope of the bypass regulating valve of the post-ultra-fast cooling system is calculated. When the head of the steel strip reaches the first header of the post-ultra-fast cooling system, the input of the closed-loop calculation of the pressure of the front ultra-fast cooling system and the closed-loop calculation of the header flow is cancelled. This is because the main concern at this time is the cooling and pressure control of the steel strip head by the post-ultra-fast cooling system, avoiding the interference of the closed-loop control of the front system on the post-ultra-fast cooling system, so that the post-ultra-fast cooling system can independently and accurately cool and pressure-regulate the steel strip head.

[0039] Specifically, the compensation value of the bypass regulating valve of the post-super-fast cooling system complies with the formula: ; In the formula, The set total water volume of the post-ultra-fast cooling system issued by the process automation system, m³ / h; The number of bypass regulating valves of the front ultra-fast cooling system; The number of bypass regulating valves of the post-mounted ultra-fast cooling system; The opening size of the bypass regulating valve of the pre-stage ultra-fast cooling system when the system pressure is stabilized within the set pressure range after the pressure closed loop is calculated; The opening degree of the bypass regulating valve of the post-mounted ultra-fast cooling system is initially set; is the actual water volume of the front ultra-fast cooling system, m³ / h; The amount of water fed back after the pump station system is upgraded; It is the maximum discharge capacity of the sewage pipeline.

[0040] The compensation slope of the bypass regulating valve of the post-mounted ultra-fast cooling system conforms to the formula: ; In the formula, is the compensation value of the bypass regulating valve of the post-super-fast cooling system, is the strip threading speed, m / s; is the cooling area length of the post-ultra-fast cooling system, m.

[0041] Step nine: When the head of the strip is in the cooling area of ​​the rear ultra-fast cooling system, the bypass regulating valve of the rear ultra-fast cooling system is adjusted according to the calculated compensation slope; when the head of the strip leaves the cooling area of ​​the rear ultra-fast cooling system, the front and rear ultra-fast cooling systems are put into pressure closed-loop calculation and manifold flow closed-loop calculation.

[0042] In this embodiment, when the head of the steel strip is in the cooling area of ​​the rear ultra-fast cooling system, the bypass regulating valve of the rear ultra-fast cooling system is adjusted according to the calculated compensation slope to cope with the heat exchange changes and flow demand changes of the head of the steel strip in the rear ultra-fast cooling system and stabilize the system pressure. When the head of the steel strip leaves the cooling area of ​​the rear ultra-fast cooling system, the pressure closed-loop calculation and the manifold flow closed-loop calculation of the front and rear ultra-fast cooling systems are put into operation. At this time, the special cooling stage of the head of the steel strip ends, and the entire steel strip enters a comprehensive stable cooling stage. The front and rear ultra-fast cooling systems require precise closed-loop control to maintain stable pressure and flow to ensure that the cooling effect of the entire steel strip is uniform and consistent to meet product quality requirements.

[0043] Step 10: When the tail of the strip leaves the cooling area of ​​the front ultra-fast cooling system, the pump station system receives the water consumption of the rear ultra-fast cooling system sent by the basic automation system, determines the water pump frequency, and starts to reduce the frequency according to the frequency reduction curve. After it is reduced to the first specific frequency, the front ultra-fast cooling system headers are closed one by one.

[0044] In this embodiment, after the tail of the strip leaves the cooling area of ​​the front ultra-fast cooling system, the pump station system receives the water consumption information of the rear ultra-fast cooling system sent by the basic automation system. Because the cooling demand of the cooling area of ​​the front ultra-fast cooling system decreases after the tail of the strip leaves the front area, it is necessary to adjust the operating parameters of the pump station according to the water consumption of the cooling area of ​​the rear ultra-fast cooling system. Determine the frequency of the water pump and start to reduce the frequency according to the frequency reduction curve. The frequency reduction curve is designed according to the characteristics of the equipment and the process requirements to ensure that the water pump can reduce the speed steadily and avoid pressure fluctuations or other equipment failures caused by sudden speed reduction. After reducing to the first specific frequency, the header of the front ultra-fast cooling system is closed in sequence, and the supply of cooling medium in the front area is gradually reduced, so that the resources of the entire system are reasonably allocated to the cooling process of the rear area. For example, the water consumption of the rear ultra-fast cooling system is 7000m³ / h. It is determined by calculation that the water pump frequency needs to be reduced from 40Hz to 20Hz, and the frequency is reduced according to the frequency reduction curve. When the frequency drops to 20Hz, the headers of the front ultra-fast cooling system begin to be closed in sequence.

[0045] Step 11: When the tail of the strip leaves the cooling area of ​​the rear ultra-fast cooling system, the water pump frequency drops to the basic frequency. After it drops to the second specific frequency, the rear ultra-fast cooling system headers are closed in sequence.

[0046] In this embodiment, when the tail of the steel strip leaves the cooling area of ​​the post-ultra-fast cooling system, the water pump frequency drops to the base frequency, which means that the entire cooling process is nearing the end, and the system gradually returns to the initial standby state. After decreasing to the second specific frequency, the post-ultra-fast cooling system headers are closed in sequence, the cooling medium supply is completely stopped, and the cooling process of the entire steel strip is completed. At the same time, it is ensured that the pressure of the system drops steadily during the stopping process, and the equipment ends the operation state safely and orderly, preparing for the next strip rolling cooling.

[0047] Specifically, the second specific frequency is less than the first specific frequency. For example, the base frequency is 20Hz, the first specific frequency is 35Hz, and the second specific frequency is 25Hz. When the tail of the strip leaves the cooling area of ​​the rear ultra-fast cooling system, the pump station system starts to reduce the frequency. As the tail of the strip leaves, the system's demand for cooling water decreases sharply, and the pump frequency gradually decreases from the current operating frequency, such as 45Hz, according to the frequency reduction curve determined by the number of pumps-frequency-flow curve. When the frequency drops to the first specific frequency of 35Hz, the basic automation system sends a shutdown command to the manifold control module of the front ultra-fast cooling system, so the manifolds of the front ultra-fast cooling system are closed in sequence according to the predetermined shutdown order, starting from the manifold closest to the tail of the strip. This process is to gradually stop the cooling function of the front ultra-fast cooling system to avoid pressure shock caused by sudden shutdown and instability inside the cooling system. After the front ultra-fast cooling system header is closed, when the tail of the strip enters the rear ultra-fast cooling system, the water pump frequency continues to decrease. When it drops to the second specific frequency of 25Hz, the header of the rear ultra-fast cooling system also begins to close in sequence, ensuring that the entire shutdown process proceeds smoothly without causing damage to the equipment.

[0048] In this embodiment, by calculating the compensation distance of each header of the front and rear ultra-fast cooling systems, the possible pressure changes can be estimated and compensated in advance, reducing the impact of the dry head process on the pressure stability of the entire ultra-fast cooling system, so that the ultra-fast cooling system can maintain a relatively stable pressure environment when the strip head enters the cooling area. At the same time, the front ultra-fast cooling pressure closed-loop control is opened and cancelled in a timely manner. When the strip head is in different cooling areas, the pressure fluctuations caused by factors such as the change in strip speed, the opening and closing of the header, and the connection of different cooling areas are effectively balanced through the precise adjustment of the bypass regulating valve and the reasonable switching of the pressure closed-loop control, ensuring the stability of the pressure during the entire cooling process, avoiding the additional impact and wear on the pipes, valves and other equipment of the ultra-fast cooling device caused by the unstable pressure, extending the service life of the equipment, and ensuring the stable and smooth cooling process, improving product quality and production efficiency. Further, starting from the end of the rolling line update calculation, through the coordinated data collection and calculation transmission of the communication system, process automation system and basic automation system, the single header flow and total flow set value are accurately determined according to various data of the rolled piece, and transmitted to the pump station system. The pump station system determines the appropriate pump frequency and increases the frequency based on the accurate pump number-pressure-flow table, providing a basic guarantee for stable flow, so that the entire cooling process can accurately adjust the flow according to the set requirements, avoiding uneven cooling and product quality problems caused by flow fluctuations. At the same time, at different stages of the head and tail of the strip, through the reasonable control of the bypass regulating valves of the front and rear ultra-fast cooling systems, such as calculating the compensation value and compensation slope based on the difference between the set total water volume and the actual water volume, and dynamically adjusting the bypass regulating valve, effectively compensate for the flow changes caused by various factors, such as special processes at the head and switching of the cooling area at the tail, ensuring that the flow is always in a relatively stable state during the entire strip cooling process, thereby ensuring the consistency of the cooling effect and the stability of product quality.

[0049] Based on the above Figure 1 The control method shown focuses on the production process of DP590 steel with a thickness of 11.1 mm. The control method of the ultra-fast cooling system in the hot rolling production line adopted includes the following specific steps: First, after the rolling line update calculation is completed, the communication system begins to receive product data information (PDI), finishing setting data and rolling line real-time data related to DP590 steel. Subsequently, the process automation system uses specific algorithms and models to perform setting calculations for the strip cooling process based on the received data. After the calculation is completed, the process automation system will promptly send the calculation results to the basic automation system, providing a key basis for subsequent cooling control operations.

[0050] When the head of the strip reaches the finishing rolling F1 stand, the basic automation system (L1 level) receives a series of key parameters from the process control system (L2 level), including the upper header flow rate of the front ultra-fast cooling system is set to 80m³ / h, the lower header flow rate is set to 100m³ / h, and the number of opening and closing valves is determined to be 16 groups. The total water volume of the front ultra-fast cooling system is calculated to be 2880m³ / h; the upper header flow rate of the rear ultra-fast cooling system is set to 130m³ / h, the lower header flow rate is set to 150m³ / h, the number of opening and closing valves is 20 groups, the total water volume is 5600m³ / h, and the receiving pressure mode setting value is 0.85Mpa.

[0051] At the same time, when the head of the strip reaches the finishing rolling F2, the basic automation system immediately sends a frequency increase signal to the pump station system, and transmits the set pressure of 0.85Mpa and the total water volume of 10480m³ / h (including the bypass adjustment volume of 2000m³ / h) to the pump station system. The pump station system increases the water pump frequency to 45Hz based on the pre-set corresponding relationship between pressure, flow and frequency, thereby providing a stable and appropriate water pressure and water volume basis for the subsequent cooling process.

[0052] When the strip head reaches the finishing rolling F3 stand, the compensation distance of each header of the front and rear ultra-fast cooling systems is obtained through the set calculation formula according to the parameters such as the dry head length of 5m, the speed of the strip of 2.9m / s, the response time of the opening and closing valve of 0.2s, and the cooling mode of 2 issued by the process automation system. The calculation of this compensation distance is intended to estimate and compensate for the uneven cooling and pressure fluctuations that may be caused by the dry head process in advance, and ensure that the cooling system can maintain a relatively stable operating state when the strip head enters the cooling area.

[0053] When the head of the strip reaches the finishing rolling F5 stand, the initial opening of the bypass regulating valve of the front ultra-fast cooling system is set to 30%, and the initial opening of the bypass regulating valve of the rear ultra-fast cooling system is set to 30%, and the front ultra-fast cooling pressure closed-loop calculation is put into operation. In the process of calculating the pressure to be stable at 0.85Mpa, it is determined that the opening of the front bypass regulating valve should be 45%. In this way, before the strip enters the cooling area, a stable pressure environment is initially established, and the pressure is monitored and adjusted in real time with the help of the pressure closed-loop calculation to ensure the smooth start of the cooling process.

[0054] When the head of the strip reaches the finishing exit pyrometer (FDT), the closed-loop calculation of the pressure of the front ultra-fast cooling system is suspended. At this time, according to the total water volume of the front ultra-fast cooling system set by the process automation of 2880m³ / h and the actual water volume of 11000m³ / h fed back by the pump station, the compensation value of the bypass regulating valve of the front ultra-fast cooling system for the head pressure compensation is calculated to be 19.5%. At the same time, according to the speed of finishing F7 of 2.9m / s and the length of the cooling area of ​​the front ultra-fast cooling system of 18.2m, the compensation slope of the bypass regulating valve is calculated to be 4.88. By calculating and applying the compensation value and compensation slope, when the head of the strip enters the cooling area of ​​the front ultra-fast cooling system, it is possible to effectively compensate for the pressure changes caused by various factors and ensure the stability of the pressure during the cooling process.

[0055] When the head of the strip leaves the cooling area of ​​the front ultra-fast cooling system, it is put into the front ultra-fast cooling system pressure closed-loop calculation and the manifold flow closed-loop calculation again. Therefore, when the main body of the strip enters the cooling area, the accuracy of the closed-loop control can be used to ensure that the pressure and flow of the front ultra-fast cooling system are always maintained at the set ideal state, ensuring the consistency and stability of the cooling effect.

[0056] When the head of the strip reaches the laminar cooling fine-tuning section, the control system sets the total water volume of the post-ultra-fast cooling system to 5600m³ / h according to the process automation, and calculates the compensation value of the bypass regulating valve of the post-ultra-fast cooling system for the head pressure compensation to be 53.2%. And according to the speed of the finishing F7 of 2.9m / s and the length of the cooling area of ​​the post-ultra-fast cooling system of 9m, the compensation slope of the bypass regulating valve is calculated to be 11.2. When the head of the strip reaches the first header of the post-ultra-fast cooling system, the pressure closed-loop calculation of the front ultra-fast cooling system and the closed-loop calculation of the header flow are suspended, so as to concentrate on the precise control of the cooling process of the post-ultra-fast cooling system and avoid mutual interference between the front and rear systems.

[0057] When the head of the strip leaves the cooling area of ​​the rear ultra-fast cooling system, it is put back into the pressure closed-loop calculation and the manifold flow closed-loop calculation of the front and rear ultra-fast cooling systems. After that, the control system dynamically adjusts the opening state of the front and rear ultra-fast cooling manifolds according to the requirements of the product cooling process, and accurately controls the final cooling temperature of the strip to meet the target requirements through real-time adjustment of parameters such as the number of manifold openings and flow rate, thereby ensuring that the produced DP590 steel products have excellent organizational properties.

[0058] Further, Figure 2 and Figure 3 The pressure control curves of the ultrafast cooling system before and after the control method provided in this embodiment are respectively shown, so as to intuitively reflect the remarkable effect of the control method in stabilizing the pressure. Figure 4The strip temperature control situation is presented, which further proves that this control method can effectively control the strip temperature within the target range and meet the requirements of the production process.

[0059] The above disclosure only discloses several specific implementation scenarios of the present application. However, the present application is not limited thereto, and any changes that can be conceived by technicians in this field should fall within the scope of protection of the present application.

Claims

1. A control method for an ultra-fast cooling system in a hot rolling production line, wherein the ultra-fast cooling system comprises an ultra-fast cooling device, a basic automation system, a process automation system and a communication system, characterized in that: The control method comprises the following steps: Step 1: After the finishing rolling setting calculation is completed, the communication system collects the product data information of the rolled piece, the finishing rolling setting data and the real-time data of the rolling line, and transmits them to the process automation system. The process automation system completes the setting calculation of the strip cooling process based on the received data, and transmits the calculation results to the basic automation system; Step 2: When the rolled product arrives at the second rolling mill, the basic automation system transmits the single header flow, total flow and pressure mode in the set calculation results to the pump station system; Step 3: Determine the number of available water pumps. The pump station system determines the water pump frequency based on the water pump number-pressure-flow table and starts the frequency increase operation according to the frequency curve; Step 4: When the strip head reaches the third rolling mill and the strip head is in the dry head control mode, the basic automation system calculates the compensation distance of each header of the front and rear ultra-fast cooling systems according to the dry head length, strip speed, response time of the header opening and closing valve and cooling mode of the ultra-fast cooling system issued by the process automation system; Step 5: When the head of the strip arrives at the fifth rolling mill, the initial opening degree of the bypass regulating valves of the front and rear ultra-fast cooling systems is set, and the front ultra-fast cooling pressure closed-loop control is started; Step 6: When the strip head reaches the high temperature meter at the finishing exit: (1) Start the dynamic setting calculation of the strip cooling process, and dynamically adjust the opening state of the header in the cooling zone according to the measured cooling temperature, strip speed and target temperature of each section; (2) The investment in the closed-loop calculation of the pressure of the front ultra-fast cooling system is cancelled. The compensation value of the bypass regulating valve of the front ultra-fast cooling system for the pressure compensation of the strip head is calculated based on the total water volume set for the front ultra-fast cooling system issued by the process automation system and the actual water volume fed back by the pump station system. The compensation slope of the bypass regulating valve of the front ultra-fast cooling system is calculated based on the speed of the final stand of the finishing rolling mill and the length of the cooling area of ​​the front ultra-fast cooling system. Step 7: When the head of the strip is in the cooling area of ​​the front ultra-fast cooling system, the bypass regulating valve of the front ultra-fast cooling system is adjusted according to the calculated compensation slope; after the head of the strip leaves the cooling area of ​​the front ultra-fast cooling system, the front ultra-fast cooling system is put into pressure closed-loop calculation and header flow closed-loop calculation; Step 8: When the head of the strip reaches the laminar cooling fine adjustment section, the basic automation system calculates the compensation value of the bypass regulating valve of the post-ultra-fast cooling system for the pressure compensation of the head of the strip according to the total water volume set by the post-ultra-fast cooling system issued by the process automation system and the actual water volume fed back by the pump station system, and calculates the compensation slope of the bypass regulating valve of the post-ultra-fast cooling system according to the speed of the final stand of the finishing rolling mill and the length of the cooling area of ​​the post-ultra-fast cooling system; when the head of the strip reaches the first header of the post-ultra-fast cooling system, the input of the closed-loop calculation of the pressure of the front ultra-fast cooling system and the closed-loop calculation of the header flow are cancelled; Step 9: When the head of the strip is in the cooling area of ​​the rear ultra-fast cooling system, the bypass regulating valve of the rear ultra-fast cooling system is adjusted according to the calculated compensation slope; when the head of the strip leaves the cooling area of ​​the rear ultra-fast cooling system, the pressure closed-loop calculation and the manifold flow closed-loop calculation of the front and rear ultra-fast cooling systems are put into operation; Step 10: When the tail of the strip leaves the cooling area of ​​the front ultra-fast cooling system, the pump station system receives the water consumption of the rear ultra-fast cooling system sent by the basic automation system, determines the pump frequency, and starts to reduce the frequency according to the frequency reduction curve. After reducing to the first specific frequency, the front ultra-fast cooling system headers are closed in sequence; Step 11: When the tail of the strip leaves the cooling area of ​​the rear ultra-fast cooling system, the water pump frequency drops to the basic frequency. After it drops to the second specific frequency, the rear ultra-fast cooling system headers are closed in sequence.

2. The control method of the ultra-fast cooling system in the hot rolling production line according to claim 1, characterized in that: The ultra-fast cooling device comprises multiple groups of front ultra-fast cooling and multiple groups of rear ultra-fast cooling. The front ultra-fast cooling is located between the finishing mill and the laminar cooling, and the rear ultra-fast cooling is located between the laminar fine adjustment header and the coiler.

3. The control method of the ultra-fast cooling system in the hot rolling production line according to claim 1, characterized in that: In step 4, the compensation distance of each header complies with the formula: ； In the formula, is the target stem length, m; is the strip threading speed, m / s; is the valve response time, s; The number of headers opened for the ultra-fast cooling system; It is the serial number of the opening header.

4. The control method of the ultra-fast cooling system in the hot rolling production line according to claim 1, characterized in that: In step six, the compensation value of the bypass regulating valve of the front ultra-fast cooling system conforms to the formula: ； In the formula, The set total water volume of the front ultra-fast cooling system issued by the process automation system, m³ / h; The number of bypass regulating valves of the front ultra-fast cooling system; The number of bypass regulating valves of the post-mounted ultra-fast cooling system; The opening size of the bypass regulating valve of the pre-mounted ultra-fast cooling system is initially set; The opening degree of the bypass regulating valve of the post-mounted ultra-fast cooling system is initially set; The amount of water fed back after the pump station system is upgraded; It is the maximum discharge capacity of the sewage pipeline.

5. The control method of the ultra-fast cooling system in the hot rolling production line according to claim 1, characterized in that: In step six, the compensation slope of the bypass regulating valve of the front ultra-fast cooling system conforms to the formula: ； In the formula, is the compensation value of the bypass regulating valve of the front ultra-fast cooling system, is the strip threading speed, m / s; is the cooling area length of the front ultra-fast cooling system, m.

6. The control method of the ultra-fast cooling system in the hot rolling production line according to claim 1, characterized in that: In step eight, the compensation value of the bypass regulating valve of the post-super-fast cooling system complies with the formula: ； In the formula, The set total water volume of the post-ultra-fast cooling system issued by the process automation system, m³ / h; The number of bypass regulating valves of the front ultra-fast cooling system; The number of bypass regulating valves of the post-mounted ultra-fast cooling system; The opening size of the bypass regulating valve of the pre-stage ultra-fast cooling system when the system pressure is stabilized within the set pressure range after the pressure closed loop is calculated; The opening degree of the bypass regulating valve of the post-mounted ultra-fast cooling system is initially set; is the actual water volume of the front ultra-fast cooling system, m³ / h; The amount of water fed back after the pump station system is upgraded; It is the maximum discharge capacity of the sewage pipeline.

7. The control method of the ultra-fast cooling system in the hot rolling production line according to claim 1, characterized in that: In step eight, the compensation slope of the bypass regulating valve of the post-super-fast cooling system complies with the formula: ； In the formula, is the compensation value of the bypass regulating valve of the post-super-fast cooling system, is the strip threading speed, m / s; is the cooling area length of the post-ultra-fast cooling system, m.

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