A control method for temperature oscillation of an intelligent temperature model of a steel rolling heating furnace

Abstract

A control method of temperature oscillation of intelligent temperature model of a steel rolling heating furnace, comprising the following steps: an intelligent temperature model system sets a furnace temperature set value and sends; a basic automation system records an initial valve position signal and adjusts temperature after receiving the furnace temperature set value; a temperature gradient is set, the intelligent temperature model system increases or decreases according to the temperature gradient for each cycle according to a tag variable; a real-time valve position signal record position is returned; the basic automation system compares the initial valve position signal and the valve position signal record position, if the two are not equal, it indicates that the dead zone has been skipped, the basic automation system sets the tag variable to zero and sends to the intelligent temperature model system. Through the control method, the dead zone of the regulating valve itself and the dead zone generated in the operation process can be effectively solved, the system temperature setting can avoid the dead zone with small fluctuation, the production is ensured to run smoothly, and the early warning and forecast of the dead zone are realized, the large dead zone (100 DEG C and above) is stopped and alarmed, and the operation safety of the heating furnace is ensured.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel metallurgy and relates to a method for controlling temperature oscillations in an intelligent temperature model of a steel rolling heating furnace. Background Technology

[0002] Heating furnaces are indispensable thermal equipment in steel production, consuming approximately 50% of the energy in the rolling process and about 20% of the total energy consumption in steel production, making them a major energy consumer. Their function is to heat steel billets according to the production schedule, ensuring that the surface and internal temperature distribution of the billets meets rolling requirements upon exiting the furnace. Simultaneously, they must ensure uniform heating, avoiding overheating and burning, and reducing oxidation and decarburization of the billets. This provides the rolling mill with high-quality heated billets, guaranteeing smooth production.

[0003] The intelligent temperature model for steel rolling furnaces is a high-tech integrated product combining process technology, artificial intelligence, and control. Unlike traditional furnace temperature control, it uses the principles of heat conduction and radiation heat transfer. Based on the current furnace temperature, it employs the finite difference method to establish a difference equation for the temperature distribution of the billet in a continuous heating furnace, calculating the steel temperature. Then, it calculates the required furnace temperature (initial furnace temperature) using the target steel temperature and sends this initial furnace temperature value to the basic automation system (L1). This direct, object-oriented approach to steel temperature control improves the accuracy of furnace temperature control, especially billet temperature control, reduces oxidation loss and energy consumption, and accurately meets rolling requirements, thus improving the quality of the final product.

[0004] The biggest problem with the current intelligent temperature model control of steel rolling furnaces is the large temperature fluctuations caused by the dead zone of the fuel (gas, oil, etc.) regulating valve during automatic control. After analysis and research, it was found that this dead zone is caused by the continuous setting of the intelligent temperature model of the heating furnace. For example, if the model is set to 100 degrees, but the temperature does not change, the model will be set to 130 degrees or even higher, such as 150 degrees, in the next cycle. The regulating valve will only activate when the set value is greater than the dead zone value, and then the heating furnace temperature will change. Only then will the model setting be normal.

[0005] Dead zone in control valves has many causes, but friction and slippage in the control valve, torsion of the rotary valve shaft, and dead zone in the amplifier are some common forms, ranging from 1-10% or greater. Moreover, some dead zones develop during operation, severely impacting the normal and stable production of the heating furnace and the quality of the final product.

[0006] Therefore, it is very important to find a model-based control method suitable for the thermal process of billet heating, to solve the dead zone of the regulating valve itself and the dead zone generated during operation, and to ensure that the temperature setting of the intelligent temperature model system of the heating furnace avoids the dead zone with minimal fluctuations, so as to ensure smooth production. Summary of the Invention

[0007] The main objective of this invention is to provide a method for controlling temperature oscillations in an intelligent temperature model for steel rolling furnaces, in order to solve the problem of large temperature jumps during automatic control caused by the dead zone of the fuel (gas, oil, etc.) regulating valve in the existing intelligent temperature model for steel rolling furnaces.

[0008] According to one aspect of the present invention, a method for controlling temperature oscillations in an intelligent temperature model of a steel rolling heating furnace is proposed, comprising the following steps:

[0009] S1. The intelligent temperature model system for the heating furnace sets the furnace temperature setpoint for a period of time based on the current steel temperature and the initial furnace temperature. The furnace temperature setpoint is sent to the basic automation system through the communication standard OPC between the intelligent temperature model system for the heating furnace and the basic automation system.

[0010] S2. The basic automation system records the initial position of the valve position signal. After receiving the furnace temperature setpoint, it adjusts the temperature based on the furnace temperature setpoint as the target value.

[0011] S3. Set the temperature gradient. The intelligent temperature model system of the heating furnace increases or decreases the furnace temperature setpoint in each cycle according to the amount of temperature gradient based on the tag variables.

[0012] S4. During the adjustment process, the control valve returns the real-time valve position signal to the basic automation system and marks it as the valve position signal recording position.

[0013] S5. During each cycle of adjustment, the basic automation system compares the initial position of the valve position signal with the recorded position of the valve position signal. If the two are not equal, it indicates that the dead zone has been skipped. The basic automation system sets the tag variable to zero and sends it to the heating furnace intelligent temperature model system.

[0014] In an embodiment of the present invention, the temperature gradient is determined by the length of each cycle interval of the intelligent temperature model system for the heating furnace, and the temperature gradient adjustment range is 10-20℃.

[0015] In an embodiment of the present invention, during the adjustment process, the secondary controller regulates and controls the flow fluctuation, and the primary controller controls the furnace temperature. The output of the regulation is a PID control signal.

[0016] In an embodiment of the present invention, the basic automation system performs logical judgments:

[0017] If L0 == L1 THEN

[0018] LAB=1

[0019] Else

[0020] LAB=0

[0021] END

[0022] In an embodiment of the present invention, if LAB=1, the basic automation system informs the heating furnace intelligent temperature model system through OPC communication. After receiving the notification, the heating furnace intelligent temperature model system adjusts the temperature gradient setting for the next cycle from the normal 10-20℃ to 3-5℃.

[0023] In an embodiment of the present invention, the intelligent temperature model system of the heating furnace provides an alarm on the HMI interface: when the set temperature is the furnace temperature set value, the regulating valve has a dead zone, and the adjustment amount is the furnace temperature set value minus the furnace temperature initial value.

[0024] In an embodiment of the present invention, if the furnace temperature setpoint minus the initial furnace temperature is greater than TJS, the intelligent temperature model system for the heating furnace will no longer perform temperature increments, but will instead set the furnace temperature setpoint to the initial furnace temperature and send it to the basic automation system for execution, and issue an alarm on the intelligent temperature model system-level HMI interface.

[0025] In an embodiment of the present invention, TJS is the upper limit of adjustment of the intelligent temperature model system for the heating furnace. The upper limit of adjustment needs to be determined according to the operating conditions of the heating furnace, and is usually below 100°C.

[0026] In an embodiment of the present invention, the control method further includes the intelligent temperature model system of the heating furnace restoring the temperature gradient to a normal value.

[0027] In an embodiment of the present invention, the basic automation system uses temperature and flow rate cascade to achieve the furnace temperature setpoint.

[0028] This invention proposes a method for controlling temperature oscillations in an intelligent temperature model for a steel rolling furnace. Based on existing models and considering dead zone characteristics, the method adjusts and alarms for dead zones below 100°C, and simultaneously stops the intelligent temperature model from controlling the furnace temperature when the dead zone exceeds 100°C, pending further processing.

[0029] The method proposed in this invention has at least the following advantages:

[0030] (1) This invention does not require major modifications to the process or equipment, and the investment is low.

[0031] (2) Based on the existing heating furnace process control system, this invention has the prospect of being applied to all heating furnaces.

[0032] (3) This invention overcomes the inherent characteristics of the dead zone of the regulating valve, and ensures continuous, stable and high-precision production of the heating furnace within a stable and safe range, thereby achieving stable and continuous production.

[0033] (4) The present invention ultimately forms a set of control technologies that combine the heating furnace temperature tracking model and the basic automation system with equipment and control, and has the characteristics of easy transfer and promotion. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0035] Figure 1 A flowchart is shown below illustrating a method for controlling temperature oscillations in a smart temperature model of a steel rolling furnace according to an exemplary embodiment of the present invention.

[0036] Figure 2 A cascade control diagram of a basic automation system according to an exemplary embodiment of the present invention is shown;

[0037] Figure 3 A summary flowchart of an embodiment of the present invention is shown. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0039] This invention proposes a method for controlling temperature oscillations in an intelligent temperature model of a steel rolling furnace. Under periodic setting control, the intelligent temperature model calculates the required temperature for the billet in the next cycle based on the current billet temperature and process requirements. The billet temperature is then converted into furnace temperature through internal model calculations or an expert database. The furnace temperature is then transmitted to the intelligent temperature model system via communication between the intelligent temperature model system and the basic automation system. The intelligent temperature model system obtains the current valve position of the regulating valve and, based on temperature-flow cascade regulation control, converts the temperature setting into flow control. This is compared with the valve position returned by the regulating control valve. If there is no change, a signal is returned to the basic automation system. The basic automation system adjusts the set temperature strategy and issues an alarm on the basic automation system's human-machine interface. The basic automation system then switches to a safe dead-zone crossing mode until it crosses the dead zone or is blocked by the dead zone.

[0040] like Figure 1 As shown, this invention provides a method for controlling temperature oscillations in a smart temperature model of a steel rolling heating furnace, comprising the following steps:

[0041] S1. The intelligent temperature model system for the heating furnace sets the furnace temperature setpoint for a period of time based on the current steel temperature and the initial furnace temperature. The furnace temperature setpoint is sent to the basic automation system through the communication standard OPC between the intelligent temperature model system for the heating furnace and the basic automation system.

[0042] S2. The basic automation system records the initial position of the valve position signal. After receiving the furnace temperature setpoint, it adjusts the temperature based on the furnace temperature setpoint as the target value.

[0043] S3. Set the temperature gradient. The intelligent temperature model system of the heating furnace increases or decreases the furnace temperature setpoint in each cycle according to the amount of temperature gradient based on the tag variables.

[0044] S4. During the adjustment process, the control valve returns the real-time valve position signal to the basic automation system and marks it as the valve position signal recording position.

[0045] S5. During each cycle of adjustment, the basic automation system compares the initial position of the valve position signal with the recorded position of the valve position signal. If the two are not equal, it indicates that the dead zone has been skipped. The basic automation system sets the tag variable to zero and sends it to the heating furnace intelligent temperature model system.

[0046] In step S1, the intelligent temperature model system for the heating furnace sets a furnace temperature setpoint for one cycle based on the current steel temperature and the initial furnace temperature. The furnace temperature setpoint is then sent to the basic automation system via the OPC communication standard between the intelligent temperature model system for the heating furnace and the basic automation system.

[0047] OPC is a data security exchange and interoperability standard used in the automation and other industries. It is platform-independent and ensures seamless information transfer between devices from multiple vendors. The OPC Foundation is responsible for the development and maintenance of this standard.

[0048] OPC standards are a set of specifications jointly developed by industry suppliers, end users, and software developers. These specifications define the interfaces between clients and servers, as well as between servers. For example, accessing real-time data, monitoring alarms and events, accessing historical data, and other applications all require the coordination of OPC standards.

[0049] The initial furnace temperature is marked as LT0, the set furnace temperature is marked as LT1, and the difference between LT0 and LT1 is the temperature gradient, which is marked as K. Thus, LT1 = LT0 + K.

[0050] Under normal circumstances, the temperature gradient is determined by the time interval of each cycle of the intelligent temperature model system for the heating furnace, and the temperature gradient adjustment range is 10-20℃.

[0051] The intelligent temperature model system for heating furnaces is based on the heat conduction and radiation heat transfer mechanisms. It uses the current furnace temperature in the steel rolling furnace as a basis, applies the finite difference method to establish the difference equation for the temperature distribution of billet in the continuous heating furnace, calculates the steel temperature, and then calculates the required furnace temperature, i.e. the initial furnace temperature, based on the target steel temperature. Finally, it sends the initial furnace temperature to the basic automation system.

[0052] In the description of this invention, the intelligent temperature model system for the heating furnace is labeled L2, the basic automation system is labeled L1, and the regulating control valve is labeled L0.

[0053] In step S2, the basic automation system records the initial position of the valve position signal. After receiving the furnace temperature setpoint, it adjusts the temperature using the furnace temperature setpoint as the target value.

[0054] After receiving the furnace temperature setpoint, the basic automation system uses the furnace temperature setpoint as the target value for temperature control.

[0055] like Figure 2 As shown, the basic automation system uses temperature and flow rate cascade to achieve the furnace temperature setpoint.

[0056] In step S2, a temperature gradient is set, and the intelligent temperature model system of the heating furnace increments or decrements the temperature gradient for each cycle according to the labeled variables.

[0057] Furthermore, before adjustment and control, the basic automation system records the current valve position signal and marks it as F0.

[0058] Furthermore, the secondary regulator regulates and controls the flow fluctuations, and its regulation output is a PID regulation signal.

[0059] Furthermore, the main controller controls the furnace temperature, and the output is a PID control signal.

[0060] Furthermore, under the aforementioned cascade regulation, the regulating control valve returns a real-time valve position signal to the basic automation system, and the valve position signal recording bit is marked as F1.

[0061] Furthermore, the basic automation system performs logical judgments:

[0062] If L0 == L1 THEN

[0063] LAB=1

[0064] Else

[0065] LAB=0

[0066] END

[0067] Furthermore, if LAB = 1, L1 informs L2 via OPC communication. Upon receiving this information, L2 sets the temperature gradient K for the next calculation cycle LT1, adjusting it from the normal 10-20℃ to 3-5℃, i.e.:

[0068] LT1 = LT0 + K

[0069] The Chinese character recognition of the labeled variables is categorized into high, medium, and low values ​​to mark the values.

[0070] If LAB=1, the basic automation system informs the heating furnace intelligent temperature model system via OPC communication. After receiving the notification, the heating furnace intelligent temperature model system adjusts the temperature gradient of the furnace temperature setpoint for the next calculation cycle from the normal 10-20℃ to 3-5℃.

[0071] Furthermore, Level L2 will display an alarm on the HMI interface, stating that when the set temperature is LT1, the regulating valve has a dead zone and the adjustment range is LT1-LT0.

[0072] Furthermore, if LT1-LT0>TJS, L2 will no longer increment the temperature, but will set LT1 to LT0 and send it to L1 for execution, and issue a red alarm on the L2-level HMI interface, with the alarm message "L1 regulating valve dead zone is too large, affecting safe production".

[0073] Furthermore, TJS is the upper limit of L2 adjustment, which needs to be determined according to the operating conditions of the heating furnace, and is generally below 100℃.

[0074] During each cycle adjustment process, L1 compares F0 with F1. If F0 is not equal to F1, it indicates that the dead zone has been skipped. L1 sets the label variable LAB to 0 and sends it to L2.

[0075] Furthermore, L2 restores the temperature gradient to its normal value, i.e., 10-20℃.

[0076] The logical judgment rule is as follows:

[0077] If F0 = ! F1 THEN

[0078] LAB=0

[0079] OPC…

[0080] K=""

[0081] In an embodiment of the present invention, the intelligent temperature model system L2 of the heating furnace is organically combined with the basic automation system L1 and the regulating control valve L0 to solve the dead zone of the regulating control valve itself and the dead zone generated during operation. This allows the temperature setting of L2 to avoid the dead zone with minimal fluctuations, ensuring smooth production. At the same time, it enables early warning and forecasting of the dead zone and provides a shutdown alarm for large dead zones (100°C and above) to ensure the safe operation of the heating furnace.

[0082] Example 1

[0083] A domestic steel plant, with an annual steel production capacity of 2 million tons, uses an intelligent temperature tracking model for furnace control, employing coal gas as the heating medium. The furnace has eight coal gas flow regulating valves, the model's operating cycle is 90 seconds, and the set temperature gradient is 20°C. Due to the inherent and temporary dead zones of the regulating valves, the furnace temperature has repeatedly fluctuated between 40-200°C, affecting the quality of the final product and even causing fluctuations in the coal gas pipeline network, leading to production shutdowns.

[0084] Upon recommendation, this invention was adopted for the optimized control of the intelligent temperature tracking mathematical model of the heating furnace.

[0085] Combined with technical solutions, such as Figure 2 As shown, the specific implementation steps of the present invention are as follows:

[0086] (1) L2 sets the furnace temperature LT1 within a cycle based on the current steel temperature and furnace temperature LT0. LT1 is sent to L1 through the communication standard OPC between L2 and L1.

[0087] Furthermore, the increment or decrement K from LT0 to LT1 is 15°C;

[0088] That is: LT1 = LT0 + 15;

[0089] (2) After L1 receives LT1, it performs temperature control with LT1 as the target value;

[0090] Furthermore, such as Figure 3 As shown, L1 uses temperature and flow rate cascade to realize the temperature of LT1;

[0091] Furthermore, before adjustment and control, L1 records the initial position F0 of the valve position signal;

[0092] Furthermore, the secondary controller regulates and controls the flow fluctuations, and its regulation output is a PID regulation signal;

[0093] Furthermore, the main controller controls the furnace temperature, and the output is a PID control signal;

[0094] Furthermore, under the above cascade regulation, the regulating valve returns the real-time valve position signal to L1, and the valve position signal recording bit F1;

[0095] Furthermore, L1 performs logical judgments:

[0096] If L0 == L1 THEN

[0097] LAB=1

[0098] Else

[0099] LAB=0

[0100] END

[0101] Furthermore, assuming LAB = 1, L1 informs L2 via OPC communication. Upon receiving this information, L2 sets a temperature gradient K, where K = 3℃, for the next computation cycle LT1. Therefore:

[0102] LT1 = LT1 + K

[0103] (3) L2 increments or decrements the amount of K in each cycle based on the label variable LAB=1;

[0104] Furthermore, Level L2 will display an alarm on the HMI interface: when the set temperature is LT1, the regulating valve has a dead zone, and the adjustment range is LT1-LT0;

[0105] Furthermore, if LT1-LT0>TJS, L2 will no longer increment the temperature, but will set LT1 to LT0 and send it to L1 for execution, and issue a red alarm "L1 regulating valve dead zone is too large, affecting safe production" on the L2 level HMI interface;

[0106] Furthermore, TJS is the upper limit of L2 regulation, TJS = 80;

[0107] (4) During each cycle adjustment process, L1 compares F0 with F1. If F0 is not equal to F1, it indicates that the dead zone has been skipped. L1 sets the label variable LAB to 0 and sends it to L2.

[0108] Furthermore, L2 assigns a value to K, K = 20.

[0109] If F0 = ! F1 THEN

[0110] LAB=0

[0111] OPC…

[0112] K=""

[0113] The reduction in violent oscillations in the heating furnace resulted in a 0.23% decrease in the rate of product quality downgrades and reclassifications, contributing 0.8% to the project's overall performance.

[0114] Reduced downgrade reversal rate × Output benefited by this process × Technological contribution - R&D investment

[0115] The downgrade reclassification rate decreased by 0.23%, and the price difference between downgraded and genuine products was 2200 yuan / ton.

[0116] Benefits: W2 = (0.23 * 200) / 100 * 2200 * 0.8 = 8.096 million yuan, so the project generated 8.096 million yuan in benefits during its implementation period.

[0117] Through the above measures, the present invention solves the following problems:

[0118] (1) Reduce the control oscillations and the impact on product quality caused by the dead zone of the regulating valve in the intelligent temperature model heating furnace control system;

[0119] (2) It integrates process technology and automated control technology, and has a high technological content;

[0120] (3) It solves the long-standing problem of the heating furnace’s stable operation, and can ensure that the heating furnace using the intelligent temperature model operates in a safe and stable state, while also having the ability to predict and control dead zones.

[0121] The intelligent temperature model temperature oscillation control method for steel rolling furnaces proposed in this invention provides furnace operators with a more suitable method for controlling temperature oscillations. This allows furnace operators to grasp the thermal state of the furnace more timely and accurately, ensuring that the system temperature setting avoids dead zones with minimal fluctuations, thus guaranteeing smooth production. At the same time, it enables early warning and forecasting of dead zones, and provides alarms for large dead zones (100°C and above), ensuring the safe operation of the furnace. This method has economical and efficient benefits.

[0122] The above are exemplary embodiments disclosed in this invention. The order of the disclosed embodiments is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. However, it should be noted that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the disclosed embodiments of this invention (including the claims) is limited to these examples. Various changes and modifications can be made without departing from the scope defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular.

[0123] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for controlling temperature oscillations in an intelligent temperature model of a steel rolling heating furnace, characterized in that, Includes the following steps: S1. The intelligent temperature model system for the heating furnace sets the furnace temperature setpoint for a period of time based on the current steel temperature and the initial furnace temperature. The furnace temperature setpoint is sent to the basic automation system through the communication standard OPC between the intelligent temperature model system for the heating furnace and the basic automation system. S2. The basic automation system records the initial position of the valve position signal. After receiving the furnace temperature setpoint, it adjusts the temperature based on the furnace temperature setpoint as the target value. S3. Set the temperature gradient. The intelligent temperature model system of the heating furnace increases or decreases the furnace temperature setpoint in each cycle according to the amount of temperature gradient based on the tag variables. S4. During the adjustment process, the control valve returns the real-time valve position signal to the basic automation system and marks it as the valve position signal recording position. S5. During each cycle of adjustment, the basic automation system compares the initial position of the valve position signal with the recorded position of the valve position signal. If the two are not equal, it indicates that the dead zone has been skipped. The basic automation system sets the tag variable to zero and sends it to the heating furnace intelligent temperature model system. The temperature gradient is determined by the time interval of each cycle of the intelligent temperature model system for the heating furnace, and the temperature gradient adjustment range is 10-20℃. During the regulation process, the secondary controller regulates and controls the flow fluctuations, while the primary controller controls the furnace temperature. The output of both controllers is a PID regulation signal. The basic automation system makes the following logical judgments: If L0 == L1 THEN LAB=1 Else LAB=0 END; If LAB=1, the basic automation system informs the heating furnace intelligent temperature model system through OPC communication. After receiving the information, the heating furnace intelligent temperature model system adjusts the temperature gradient setting for the next cycle from the normal 10-20℃ to 3-5℃. The basic automation system uses temperature and flow rate cascade to achieve the furnace temperature setpoint.

2. The control method according to claim 1, characterized in that, The intelligent temperature model system for the heating furnace will issue an alarm on the HMI interface: when the set temperature is the furnace temperature setpoint, the regulating valve has a dead zone, and the adjustment amount is the furnace temperature setpoint minus the initial furnace temperature value.

3. The control method according to claim 2, characterized in that, If the furnace temperature setpoint minus the initial furnace temperature exceeds the adjustment limit of the intelligent temperature model system for the heating furnace, the intelligent temperature model system will no longer increment the temperature. Instead, it will set the furnace temperature setpoint to the initial furnace temperature and send it to the basic automation system for execution, and issue an alarm on the intelligent temperature model system-level HMI interface.

4. The control method according to claim 3, characterized in that: The upper limit of adjustment needs to be determined according to the operating conditions of the heating furnace, wherein the upper limit of adjustment is below 100°C.

5. The control method according to claim 2, characterized in that: The control method also includes the intelligent temperature model system of the heating furnace restoring the temperature gradient to a normal value.

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