A method for production early warning and strip running speed control in annealing furnace area

Abstract

This application provides a method for production warning and strip running speed control in an annealing furnace, relating to the field of annealing furnace control technology. The method includes: obtaining the actual hourly output of the annealing furnace and obtaining the maximum hourly output limited by the critical risk index of the radiant tube; issuing a furnace area production warning based on the actual hourly output and the maximum hourly output limited by the critical risk index of the radiant tube; and adjusting the upper limit of the strip running speed within the annealing furnace after issuing the furnace area production warning. The technical solution of this application achieves production warning through the maximum hourly output limited by the critical risk index of the radiant tube; and achieves speed control after the warning by controlling the furnace area speed to prevent radiant tube cracking.

Description

Technical Field

[0001] This application relates to the field of annealing furnace control technology, and more specifically, to a method for production early warning and strip running speed control in the annealing furnace area. Background Technology

[0002] In unit production, problems frequently arise such as an excessive number of faulty burners, leading to insufficient heating capacity to meet design requirements and impacting production output; or, underproduction necessitates the use of thicker gauge burners to catch up. The usual approach is to increase the upper limit of the tube temperature to improve heating capacity. However, this undoubtedly exacerbates the risk of radiant tube cracking. As the number of burners failing to burn properly due to radiant tube cracking increases, heating capacity is further reduced. This vicious cycle, over a long period, causes the upper limit of the radiant tube temperature to gradually increase, resulting in the radiant tubes operating in an "overheated" state for extended periods. Under the combined effects of high-temperature creep and high-temperature oxidation corrosion, straight tubes eventually crack.

[0003] The problem of cracking of the radiant tubes in the 1700 continuous annealing furnace has not yet been resolved. The control measure is to replace the radiant tubes during furnace cleaning and maintenance. However, replacing the radiant tubes will increase the cost. In order to control maintenance costs, it is urgent to find a way to increase the time before the radiant tubes crack and extend their service life. Summary of the Invention

[0004] The embodiments of this application provide a method for production early warning and strip running speed control in the annealing furnace area. This method achieves production early warning by limiting the maximum hourly output based on the critical risk index of the radiant tube; and achieves speed control after early warning by controlling the furnace area speed to prevent cracking of the radiant tube.

[0005] Other features and advantages of this application will become apparent from the following detailed description, or may be learned in part from practice of this application.

[0006] According to a first aspect of the embodiments of this application, a method for production early warning and strip running speed control in an annealing furnace zone is provided, comprising: Obtain the actual hourly output of the annealing furnace, and obtain the maximum hourly output limited by the critical risk index of the radiant tube; Early warning of furnace area output is based on the actual hourly output of the annealing furnace and the maximum hourly output limited by the critical risk index of the radiant tube. After issuing a production warning for the furnace area, the upper limit of the running speed of the strip steel in the annealing furnace is adjusted.

[0007] In some embodiments of this application, based on the foregoing scheme, obtaining the actual hourly output of the annealing furnace includes: Obtain the actual thickness of the strip in the heating section, the actual width of the strip in the heating section, the running speed of the strip in the furnace, and the density of the strip; Based on the actual thickness of the strip in the heating section, the actual width of the strip in the heating section, the running speed of the strip in the furnace, and the density of the strip, the actual hourly output of the annealing furnace is calculated using formula (1). ; (1) Formula (1), This represents the actual hourly output of the annealing furnace at the current annealing temperature. This refers to the actual thickness of the strip steel in the heating section; This refers to the actual width of the strip steel in the heating section; This refers to the running speed inside the strip steel furnace; It is the density of the strip steel.

[0008] In some embodiments of this application, based on the foregoing scheme, obtaining the maximum hourly output limited by the critical risk index of the radiation tube includes: Obtain the risk index of radiant tube cracking; The maximum hourly output limited by the critical risk index of the radiant tube is calculated based on the radiant tube cracking risk index.

[0009] In some embodiments of this application, based on the foregoing scheme, obtaining the radiant tube cracking risk index includes: The power used per unit area of ​​the radiant tube is obtained based on formula (2); ; (2) In formula (2), Power used per unit area of ​​the radiant tube; This represents the maximum hourly output of the annealing furnace at the current annealing temperature. This represents the total number of radiation tubes in the i-th column; The average number of failures in the i-th column of radiator tubes; The surface area of ​​the radiant tube; For radiant tube heating efficiency; This represents the change in enthalpy of the strip steel in the heating section. Based on the power used per unit area of ​​the radiant tube, the design power per unit area of ​​the radiant tube, and the reference value of the surface power of the radiant tube, the cracking risk index of the radiant tube is calculated using formula (3). ; (3) In formula (3), The risk index for cracking of radiant tubes; Power used per unit area of ​​the radiant tube; Design power per unit area for the radiant tubes in column i; This represents the total number of radiation tubes in the i-th column; The average number of failures in the i-th column of radiator tubes; This is the reference value for the surface power of the radiating tube.

[0010] In some embodiments of this application, based on the foregoing scheme, the step of calculating the maximum hourly output limited by the critical risk index of the radiant tube based on the radiant tube cracking risk index includes: Set the risk index of radiant tube cracking to be equal to the critical risk index of radiant tube cracking. The maximum hourly output limited by the critical risk index of the radiation tube is calculated based on formula (4); (4) In formula (4), The maximum hourly output is limited by the critical risk index of the radiant tube under the current furnace condition. The critical cracking risk index for radiant tubes; This represents the total number of radiation tubes in the i-th column; The average number of failures in the i-th column of radiator tubes; The surface area of ​​the radiant tube; For radiant tube heating efficiency; This represents the change in enthalpy of the strip steel in the heating section. Design power per unit area for the radiant tubes in column i; This is the reference value for the surface power of the radiating tube.

[0012] In some embodiments of this application, based on the foregoing scheme, the step of providing early warning of furnace output based on the actual hourly output of the annealing furnace and the maximum hourly output limited by the critical risk index of the radiant tube includes: when At that time, a Level 1 warning will be issued; when At that time, a level-two warning will be issued; in, This represents the actual hourly output of the annealing furnace at the current annealing temperature. The maximum hourly output is limited by the critical risk index of the radiant tube under the current furnace condition. The first hour's production warning threshold; This is the production warning threshold for the second hour.

[0013] In some embodiments of this application, based on the foregoing scheme, adjusting the upper limit of the strip running speed in the annealing furnace after issuing a furnace area production warning includes: After issuing a level-two warning, calculate the upper limit of furnace zone velocity to prevent radiant tube cracking; The upper limit of the running speed of the strip in the annealing furnace is adjusted from the maximum design speed of the annealing furnace to the upper limit of the furnace zone speed to prevent cracking of the radiant tubes.

[0014] In some embodiments of this application, based on the foregoing scheme, the calculation of the upper limit of the furnace zone velocity to prevent radiant tube cracking includes: The maximum speed limited by the heating capacity of the annealing furnace and the maximum speed limited by the prevention of cracking of the radiant tubes; Based on the maximum speed limited by the heating capacity of the annealing furnace and the maximum speed limited to prevent cracking of the radiant tube, the upper limit of the furnace zone speed to prevent cracking of the radiant tube is calculated using formula (5). ; (5) In formula (5), The upper limit of furnace zone speed to prevent radiant tube cracking; The maximum speed limited by the heating capacity of the annealing furnace; The maximum speed is limited to prevent the radiant tube from cracking.

[0015] In some embodiments of this application, based on the foregoing scheme, obtaining the maximum speed limited by the heating capacity of the annealing furnace includes: Obtain the maximum hourly output, actual thickness of strip steel in heating section, actual width of strip steel in heating section, strip steel density, design reference width of annealing furnace, and second hourly output warning threshold based on the critical risk index of radiant tube under current furnace conditions; Based on the current furnace condition, the maximum hourly output limited by the critical risk index of the radiant tube, the actual thickness of the strip in the heating section, the actual width of the strip in the heating section, the strip density, the design reference width of the annealing furnace, and the warning threshold of the second hourly output, the maximum speed limited by the heating capacity of the annealing furnace is calculated using formula (6). ; (6) In formula (6), The maximum speed is limited to prevent the radiant tube from cracking; The maximum hourly output is limited by the critical risk index of the radiant tube under the current furnace condition. This refers to the actual thickness of the strip steel in the heating section; This refers to the actual width of the strip steel in the heating section; It is the density of the strip steel; Design the reference width for the annealing furnace; This is the production warning threshold for the second hour.

[0016] In some embodiments of this application, based on the foregoing scheme, obtaining the maximum speed limiting the prevention of radiant tube cracking includes: Obtain the maximum design speed of the annealing furnace, the setpoint of the annealing temperature in the heating section, the design reference width of the annealing furnace, the actual thickness of the strip in the heating section, and the actual width of the strip in the heating section; Based on the maximum design speed of the annealing furnace, the set value of the annealing temperature of the heating section, the design reference width of the annealing furnace, the actual thickness of the strip steel in the heating section, and the actual width of the strip steel in the heating section, the maximum speed for preventing cracking of the radiant tube is calculated using formula (7). (7) In formula (7), This is the maximum speed of the annealing furnace; The annealing furnace is designed for maximum speed; This is the annealing temperature setting value for the heating section; Design the reference width for the annealing furnace; This refers to the actual thickness of the strip steel in the heating section; This refers to the actual width of the strip steel in the heating section; The reference thickness for the annealing furnace design; This is the reference thickness for the strip steel.

[0017] The technical solution of this application achieves production early warning by limiting the maximum hourly output based on the critical risk index of the radiant tube; and achieves speed control after the early warning by controlling the furnace zone speed to prevent the radiant tube from cracking.

[0018] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings: Figure 1 A flowchart illustrating a method for production early warning and strip running speed control in an annealing furnace zone according to an embodiment of this application is shown. Figure 2 A schematic diagram showing the relationship between the enthalpy of a strip steel and temperature according to an embodiment of this application is provided. Figure 3 A schematic diagram showing the relationship between power consumption per unit area of ​​a radiant tube, annealing temperature, and burner failure rate according to an embodiment of this application is provided. Figure 4 A schematic diagram showing the relationship between the radiant tube cracking risk index and annealing temperature and burner failure rate according to an embodiment of this application is provided. Figure 5 The diagram illustrates the influence of burner failure rate and annealing temperature on the hourly output limit of the annealing furnace when the critical cracking risk index is 0.8 according to one embodiment of this application. Figure 6 The diagram illustrates the influence of burner failure rate and annealing temperature on the hourly output limit of the annealing furnace when the critical cracking risk index is 1 according to an embodiment of this application. Detailed Implementation

[0020] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art.

[0021] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0022] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0023] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0024] It should be noted that "multiple" in this article refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0025] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such uses of these terms can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described.

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0027] The following detailed description of some embodiments of this application will be provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0028] See Figure 1 The diagram shows a flow chart of a method for production early warning and strip running speed control in an annealing furnace zone according to an embodiment of this application.

[0029] like Figure 1 As shown, a method for production early warning and strip running speed control in an annealing furnace zone is presented, which specifically includes steps S100 to S300.

[0030] Step S100: Obtain the actual hourly output of the annealing furnace and the maximum hourly output limited by the critical risk index of the radiant tube.

[0031] It is understandable that the actual hourly output of the annealing furnace refers to the amount of strip steel that the annealing furnace can produce in a single hour, while the maximum hourly output limited by the critical risk index of the radiant tube refers to the amount of strip steel that the annealing furnace can produce in a single hour when the radiant tube is on the verge of cracking.

[0032] In some feasible embodiments, obtaining the actual hourly output of the annealing furnace includes: Obtain the actual thickness of the strip in the heating section, the actual width of the strip in the heating section, the running speed of the strip in the furnace, and the density of the strip; Based on the actual thickness of the strip in the heating section, the actual width of the strip in the heating section, the running speed of the strip in the furnace, and the density of the strip, the actual hourly output of the annealing furnace is calculated using formula (1). ; (1) in, The actual hourly output of the annealing furnace at the current annealing temperature, in tons per hour (t / h). The actual thickness of the strip in the heating section, in mm; This refers to the actual width of the strip in the heating section, in mm. The speed of the strip inside the furnace is m / min; The density of the strip steel is 7.850 t / m³. 3 .

[0033] It is understandable that the actual thickness of the strip in the heating section, the actual width of the strip in the heating section, the running speed of the strip in the furnace, and the density of the strip can be directly obtained during the actual production process of the strip. Among them, the running speed of the strip in the furnace refers to the speed at which the strip runs in the annealing furnace. The running speed of the strip in the furnace has a direct impact on the production volume of the strip. The faster the speed, the more strip is produced.

[0034] In some feasible embodiments, obtaining the maximum hourly output defined by the critical risk index of the radiation tube includes: Obtain the risk index of radiant tube cracking; The maximum hourly output limited by the critical risk index of the radiant tube is calculated based on the radiant tube cracking risk index.

[0035] It should be noted that in this embodiment, the degree of cracking risk of the radiant tube can be determined based on the radiant tube cracking risk index, and then the maximum hourly output of strip steel can be determined within the radiant tube cracking risk range.

[0036] In some feasible embodiments, obtaining the radiant tube cracking risk index includes: The power used per unit area of ​​the radiant tube is obtained based on formula (2); ; (2) In formula (2), Power per unit area of ​​the radiant tube, kW / m 2 ; This represents the maximum hourly output of the annealing furnace at the current annealing temperature, in tons per hour (t / h). The total number of radiation tubes in the i-th column; The average number of faults in the i-th column of radiator tubes; The surface area of ​​the radiant tube is m. 2 ; For the radiant tube heating efficiency, this embodiment uses 40-55%; The change in enthalpy of the strip steel in the heating section, expressed in kcal / T; Based on the power used per unit area of ​​the radiant tube, the design power per unit area of ​​the radiant tube, and the reference value of the surface power of the radiant tube, the cracking risk index of the radiant tube is calculated using formula (3). ; (3) In formula (3), The dimensionless index represents the risk of cracking in radiant tubes. Power per unit area of ​​the radiant tube, kW / m 2 ; The design power per unit area of ​​the i-th column of radiant tubes is given in kW / m². 2 ; The total number of radiation tubes in the i-th column; The average number of faults in the i-th column of radiator tubes; The reference value for surface power of the radiant tube is kW / m. 2 .

[0037] It should be noted that in this embodiment, the radiant tubes are distributed in the heating section of the annealing furnace in an array. Based on the distribution of the radiant tubes, the total number of radiant tubes, the number of faults, the surface area of ​​the radiant tubes, the heating efficiency, and the change in enthalpy of the strip in the heating section need to be obtained through simple calculations. Such calculations are relatively conventional and will not be described in this embodiment.

[0038] In this embodiment, a calculation model for the cracking risk index of the radiant tube is established. This model can be used to obtain the cracking risk index of the radiant tube in real time, thereby understanding the current cracking risk level of the radiant tube.

[0039] In some feasible embodiments, calculating the maximum hourly output limited by the critical risk index of the radiant tube based on the radiant tube cracking risk index includes: Set the risk index of radiant tube cracking to be equal to the critical risk index of radiant tube cracking. The maximum hourly output limited by the critical risk index of the radiation tube is calculated based on formula (4); (4) In formula (4), The maximum hourly output is limited by the critical risk index of the radiant tube under the current furnace condition. The critical cracking risk index for radiant tubes; This represents the total number of radiation tubes in the i-th column; The average number of failures in the i-th column of radiator tubes; The surface area of ​​the radiant tube; For radiant tube heating efficiency; This represents the change in enthalpy of the strip steel in the heating section. Design power per unit area for the radiant tubes in column i; This is the reference value for the surface power of the radiating tube.

[0041] It is understandable that the critical cracking risk index of the radiant tube refers to the limit value of the radiant tube cracking risk index when the radiant tube is on the verge of cracking, and the maximum hourly output limited by the critical risk index of the radiant tube refers to the maximum production of strip steel in the annealing furnace per unit hour when the radiant tube is on the verge of cracking; the maximum hourly output limited by the critical risk index of the radiant tube indicates the maximum amount of strip steel that the annealing furnace can produce per unit time without the radiant tube cracking.

[0042] Continue to refer to Figure 1Step S200: Based on the actual hourly output of the annealing furnace and the maximum hourly output limited by the critical risk index of the radiant tube, a furnace area output early warning is performed.

[0043] Understandably, the actual hourly output of the annealing furnace represents the amount of strip steel that the furnace can produce per unit time during actual production; the maximum hourly output limited by the critical risk index of the radiant tube represents the amount of strip steel that the annealing furnace can produce per unit time without the radiant tube cracking, and can represent the limit of strip steel production by the annealing furnace; based on the actual output and the limit output of the strip steel, it is possible to correctly determine whether the current output of the annealing furnace meets the requirements, and thus determine whether an alarm needs to be issued.

[0044] In some feasible embodiments, step S200 specifically includes: when At that time, a Level 1 warning will be issued; when At that time, a level-two warning will be issued; in, The actual hourly output of the annealing furnace at the current annealing temperature, in tons per hour (t / h). The maximum hourly output, t / h, is defined by the critical risk index of the radiant tube under current furnace conditions. The production warning threshold for the first hour is set to 1 to 1.1 in this embodiment. The production warning threshold for the second hour is set to 1.01 to 1.3 in this embodiment.

[0045] In this embodiment, and Compare them. This indicates the maximum number of strip steel that the annealing furnace can produce. By comparing the two, it can be determined whether the current output of the annealing furnace meets the requirements, and then a first-level or second-level early warning can be issued.

[0046] Continue to refer to Figure 1 In step S300, after issuing a furnace area production warning, the upper limit of the running speed of the strip in the annealing furnace is adjusted.

[0047] It is understandable that the running speed of the strip in the annealing furnace is directly proportional to the output of the strip in the annealing furnace. If the output of the strip exceeds the required amount, the output of the strip can be adjusted by adjusting the running speed of the strip.

[0048] In some feasible embodiments, step S300 specifically includes: After issuing a level-two warning, calculate the upper limit of furnace zone velocity to prevent radiant tube cracking; The upper limit of the running speed of the strip in the annealing furnace is adjusted from the maximum design speed of the annealing furnace to the upper limit of the furnace zone speed to prevent cracking of the radiant tubes.

[0049] Understandably, when a Level 2 warning is issued, the actual hourly output of the annealing furnace is higher than when a Level 1 warning is issued. Therefore, it is urgent to adjust the running speed of the strip steel in the annealing furnace to change the output of the strip steel in the annealing furnace.

[0050] Understandably, the purpose of Level 1 and Level 2 warnings is to reduce the actual hourly output of the annealing furnace and prevent the radiant tubes from cracking. After Level 2 warning, it appears that the actual hourly output of the annealing furnace is too high and the radiant tubes are on the verge of cracking. At this point, it is necessary to adjust the strip running speed in the annealing furnace to a speed that prevents the radiant tubes from cracking.

[0051] It is understood that, in this embodiment, the maximum design speed of the annealing furnace refers to the maximum running speed of the strip steel designed in the annealing furnace; the upper limit of the furnace zone speed to prevent cracking of the radiant tubes refers to the maximum running speed of the strip steel in the annealing furnace under the condition of preventing cracking of the radiant tubes.

[0052] In some feasible embodiments, the calculation of the upper limit of the furnace zone velocity to prevent radiant tube cracking includes: The maximum speed limited by the heating capacity of the annealing furnace and the maximum speed limited by the prevention of cracking of the radiant tubes; Based on the maximum speed limited by the heating capacity of the annealing furnace and the maximum speed limited to prevent cracking of the radiant tube, the upper limit of the furnace zone speed to prevent cracking of the radiant tube is calculated using formula (5). ; (5) In formula (5), The upper limit of furnace zone velocity to prevent radiant tube cracking is 1 m / min; The maximum speed limit for the heating capacity of the annealing furnace, in m / min; The maximum speed, in m / min, is set to prevent the radiant tube from cracking.

[0053] It is understandable that the maximum speed limited by the heating capacity of the annealing furnace refers to the maximum running speed of the strip within the allowable range of the heating capacity of the annealing furnace; the maximum speed limited to prevent cracking of the radiant tube refers to the maximum running speed of the strip under the limited conditions of preventing cracking of the radiant tube in the annealing furnace. These two speeds represent the limit values ​​of the strip running speed when the radiant tube is on the verge of cracking. The smaller value between the two is selected as the upper limit of the furnace zone speed to prevent cracking of the radiant tube. At this limit speed, the radiant tube will not crack.

[0054] In some feasible embodiments, obtaining the maximum speed limited by the heating capacity of the annealing furnace includes: Obtain the maximum hourly output, actual thickness of strip steel in heating section, actual width of strip steel in heating section, strip steel density, design reference width of annealing furnace, and second hourly output warning threshold based on the critical risk index of radiant tube under current furnace conditions; Based on the current furnace condition, the maximum hourly output limited by the critical risk index of the radiant tube, the actual thickness of the strip in the heating section, the actual width of the strip in the heating section, the strip density, the design reference width of the annealing furnace, and the warning threshold of the second hourly output, the maximum speed limited by the heating capacity of the annealing furnace is calculated using formula (6). ; (6) In formula (6), The maximum speed, measured in m / min, is set to prevent the radiant tube from cracking. The maximum hourly output, t / h, is defined by the critical risk index of the radiant tube under current furnace conditions. The actual thickness of the strip in the heating section, in mm; This refers to the actual width of the strip in the heating section, in mm. The density of the strip steel is 7.850 t / m³. 3 ; The reference width for the annealing furnace design is in mm; The production warning threshold for the second hour is set at 1.01 to 1.3.

[0055] It is understood that, in this embodiment, the maximum hourly output limited by the critical risk index of the radiant tube under the current furnace condition can be calculated through the aforementioned steps, and parameters such as the actual thickness of the strip in the heating section, the actual width of the strip in the heating section, the strip density, the design reference width of the annealing furnace, and the warning threshold for the second hourly output can be directly obtained in the actual production process.

[0056] In some feasible embodiments, obtaining the maximum speed limited to prevent the radiant tube from cracking includes: Obtain the maximum design speed of the annealing furnace, the setpoint of the annealing temperature in the heating section, the design reference width of the annealing furnace, the actual thickness of the strip in the heating section, and the actual width of the strip in the heating section; Based on the maximum design speed of the annealing furnace, the set value of the annealing temperature of the heating section, the design reference width of the annealing furnace, the actual thickness of the strip steel in the heating section, and the actual width of the strip steel in the heating section, the maximum speed for preventing cracking of the radiant tube is calculated using formula (7). (7) In formula (7), The limiting speed of the annealing furnace is in m / min, which is related to the maximum design speed of the unit and the speed limited by the heating capacity. The maximum design speed for the annealing furnace is in m / min; This is the setpoint for the annealing temperature of the heating section, in °C; The reference width for the annealing furnace design is in mm; The actual thickness of the strip in the heating section, in mm; This refers to the actual width of the strip in the heating section, in mm. The reference thickness for the annealing furnace design; This is the reference thickness for the strip steel.

[0057] Understandably, parameters such as the maximum design speed of the annealing furnace, the set value of the annealing temperature in the heating section, the design reference width of the annealing furnace, the actual thickness of the strip in the heating section, and the actual width of the strip in the heating section can be directly obtained during the actual production process.

[0058] Below is a practical example of applying this method.

[0059] Taking Shougang Jingtang 1700 continuous annealing furnace as an example, the radiant tubes in the heating section are distributed in 7 layers and 25 columns, totaling 334 W-shaped radiant tubes.

[0060] The total number of radiant tubes in each row and their design power are shown in Table 1.

[0061] Table 1. Relevant parameters of Shougang Jingtang cold-rolled 1700 continuous annealed radiant tubes

[0062] Annealing furnace design reference thickness Take -0.00196 mm / ℃; the reference thickness of the strip at an annealing temperature of 700℃. Take 0.86314 mm; Reference width Take 1350 mm; power reference value of radiant tube surface. P s_std Take 20kw / m 2 Radiant tube heating efficiency η Take 50%; radiant tube surface area S w_tube Take 5.115m 2 High hourly output alarm threshold k 1.025; High-level alarm threshold for hourly output k 2 is 1.05.

[0063] 1. Calculate the change in enthalpy of the strip steel in the heating section.

[0064] The enthalpy values ​​of strip steel at different temperatures, such as Figure 2 As shown.

[0065] By fitting, the relationship between the enthalpy of the strip steel and the temperature can be obtained, as shown in formula (8); ; (8) In formula (8): For strip steel at temperatureT Enthalpy of heat at time, kcal / T; T The strip temperature is ℃.

[0066] The change in enthalpy of the strip in the heating section is further obtained, as shown in formula (9); (9) Formula (9): The change in enthalpy of the strip steel in the heating section, expressed in kcal / T; The temperature of the strip at the outlet of the heating section is ℃; It is the temperature of the strip at the outlet of the preheating section, and also the temperature of the strip at the inlet of the heating section (°C).

[0067] 2. Calculate the power used per unit area of ​​the radiant tube.

[0068] The strip steel at the inlet temperature of the heating section StripT JPF At 120℃, the surface power reference value of the radiant tube. P s_std Take 20, kW / m 2 Radiant tube heating efficiency η Take 50%; radiant tube surface area S w_tube Take 5.115m 2 According to formula (1), the relationship between the power consumption per unit area of ​​the radiant tube and the annealing temperature, burner failure rate, and hourly output can be obtained, such as... Figure 3 As shown.

[0069] 3. Calculate the risk index of radiant tube cracking.

[0070] The strip steel at the inlet temperature of the heating section StripT JPF At 120℃, the surface power reference value of the radiant tube. P s_std Take 20, kW / m 2 Radiant tube heating efficiency η Take 50%; radiant tube surface area S w_tube Take 5.115m 2 According to formula (2), the risk index of radiant tube cracking under different hourly outputs can be obtained. k w_tube The relationship between annealing temperature and burner failure rate, such as Figure 4 As shown. As annealing temperature, hourly output, and burner failure rate increase, the risk index of radiant tube cracking also increases.

[0071] 4. Calculate the maximum hourly output limited by the critical risk index of the radiation tube.

[0072] The strip steel at the inlet temperature of the heating section StripT JPF At 120℃, the surface power reference value of the radiant tube. P s_std Take 20, kW / m 2 Radiant tube heating efficiency η Take 50%; radiant tube surface area S w_tube Take 5.115m 2 According to formula (2), the maximum hourly output of the radiant tube under different critical cracking risk indices can be obtained. PR HL_T The relationship between annealing temperature and burner failure rate, such as Figure 5 , Figure 6 As shown.

[0073] 5. Adjust the upper limit of the running speed of the strip in the annealing furnace.

[0074] Set the hourly output high alarm threshold k 2. Take 1.05, the strip inlet temperature of the heating section StripT JPF Take 120℃ as the temperature of the strip at the outlet of the heating section. StripT RTF 790℃; Radiant tube surface power reference value P s_std Take 20, kW / m 2 Radiant tube heating efficiency η Take 50%; radiant tube surface area S w_tube Take 5.115m 2 According to formula (6), the upper limit of the running speed of the strip in the annealing furnace and the strip specifications can be obtained under different critical cracking risk indices. PR HL_T The relationship between annealing temperature and burner failure rate is used to adjust the running speed of strip steel in the annealing furnace.

[0075] Through the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein can be implemented by software or by combining software with necessary hardware. Therefore, the technical solutions according to the embodiments of this application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, external hard drive, etc.) or on a network, including several instructions to cause a computing device (such as a personal computer, server, touch terminal, or network device, etc.) to execute the methods according to the embodiments of this application.

[0076] Other embodiments of this application will readily conceive of by those skilled in the art upon consideration of the specification and practice of the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. It should be understood that this application is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for early warning of output and control of strip running speed in an annealing furnace zone, characterized in that, include: Obtain the actual hourly output of the annealing furnace, and obtain the maximum hourly output limited by the critical risk index of the radiant tube; Early warning of furnace area output is based on the actual hourly output of the annealing furnace and the maximum hourly output limited by the critical risk index of the radiant tube. After issuing a furnace area production warning, the upper limit of the running speed of the strip steel in the annealing furnace is adjusted. The process of obtaining the maximum hourly output limited by the critical risk index of the radiation tube includes: Obtain the risk index of radiant tube cracking; The maximum hourly output limited by the critical risk index of the radiant tube is calculated based on the radiant tube cracking risk index. The method for obtaining the risk index of radiant tube cracking includes: The power used per unit area of ​​the radiant tube is obtained based on formula (2); ； （2） In formula (2), Power per unit area of ​​the radiant tube, kW / m 2 ; This represents the maximum hourly output of the annealing furnace at the current annealing temperature, in tons per hour (t / h). The total number of radiation tubes in the i-th column; The average number of faults in the i-th column of radiator tubes; The surface area of ​​the radiant tube is m. 2 ; The heating efficiency of the radiant tube is dimensionless. The change in enthalpy of the strip steel in the heating section, expressed in kcal / T; Based on the power used per unit area of ​​the radiant tube, the design power per unit area of ​​the radiant tube, and the reference value of the surface power of the radiant tube, the cracking risk index of the radiant tube is calculated using formula (3). ； （3） In formula (3), The dimensionless index represents the risk of cracking in radiant tubes. Power per unit area of ​​the radiant tube, kW / m 2 ; The design power per unit area of ​​the i-th column of radiant tubes is given in kW / m². 2 ; The total number of radiation tubes in the i-th column; The average number of faults in the i-th column of radiator tubes; The reference value for surface power of the radiant tube is kW / m. 2 ; The calculation of the maximum hourly output limited by the critical risk index of the radiant tube based on the radiant tube cracking risk index includes: Set the risk index of radiant tube cracking to be equal to the critical risk index of radiant tube cracking. The maximum hourly output limited by the critical risk index of the radiation tube is calculated based on formula (4); （4） In formula (4), The maximum hourly output, t / h, is defined by the critical risk index of the radiant tube under current furnace conditions. The critical cracking risk index for radiant tubes is dimensionless. The total number of radiation tubes in the i-th column; The average number of faults in the i-th column of radiator tubes; The surface area of ​​the radiant tube is m. 2 ; The heating efficiency of the radiant tube is dimensionless. The change in enthalpy of the strip steel in the heating section, expressed in kcal / T; The design power per unit area of ​​the i-th column of radiant tubes is given in kW / m². 2 ; The reference value for surface power of the radiant tube is kW / m. 2 .

2. The method according to claim 1, characterized in that, The process of obtaining the actual hourly output of the annealing furnace includes: Obtain the actual thickness of the strip in the heating section, the actual width of the strip in the heating section, the running speed of the strip in the furnace, and the density of the strip; Based on the actual thickness of the strip in the heating section, the actual width of the strip in the heating section, the running speed of the strip in the furnace, and the density of the strip, the actual hourly output of the annealing furnace is calculated using formula (1). ； （1） In formula (1), The actual hourly output of the annealing furnace at the current annealing temperature, in tons per hour (t / h). The actual thickness of the strip in the heating section, in mm; This refers to the actual width of the strip in the heating section, in mm. The speed of the strip inside the furnace is m / min; It is the density of strip steel, t / m 3 .

3. The method according to claim 1, characterized in that, The method of providing early warning of furnace output based on the actual hourly output of the annealing furnace and the maximum hourly output limited by the critical risk index of the radiant tube includes: when At that time, a Level 1 warning will be issued; when At that time, a level-two warning will be issued; in, The actual hourly output of the annealing furnace at the current annealing temperature, in tons per hour (t / h). The maximum hourly output, t / h, is defined by the critical risk index of the radiant tube under current furnace conditions. The first hour's production warning threshold; This is the production warning threshold for the second hour.

4. The method according to claim 3, characterized in that, The adjustment of the upper limit of the running speed of strip steel in the annealing furnace after issuing a furnace area production warning includes: After issuing a level-two warning, calculate the upper limit of furnace zone velocity to prevent radiant tube cracking; The upper limit of the running speed of the strip in the annealing furnace is adjusted from the maximum design speed of the annealing furnace to the upper limit of the furnace zone speed to prevent cracking of the radiant tubes.

5. The method according to claim 4, characterized in that, The calculation of the upper limit of furnace zone velocity to prevent radiant tube cracking includes: The maximum speed limited by the heating capacity of the annealing furnace and the maximum speed limited by the prevention of cracking of the radiant tubes; Based on the maximum speed limited by the heating capacity of the annealing furnace and the maximum speed limited to prevent cracking of the radiant tube, the upper limit of the furnace zone speed to prevent cracking of the radiant tube is calculated using formula (5). ； （5） In formula (5), The upper limit of furnace zone velocity to prevent radiant tube cracking is 1 m / min; The maximum speed limit for the heating capacity of the annealing furnace, in m / min; The maximum speed, in m / min, is set to prevent the radiant tube from cracking.

6. The method according to claim 5, characterized in that, The maximum speed at which the heating capacity of the annealing furnace is limited includes: Obtain the maximum hourly output, actual thickness of strip steel in heating section, actual width of strip steel in heating section, strip steel density, design reference width of annealing furnace, and second hourly output warning threshold based on the critical risk index of radiant tube under current furnace conditions; Based on the current furnace condition, the maximum hourly output limited by the critical risk index of the radiant tube, the actual thickness of the strip in the heating section, the actual width of the strip in the heating section, the strip density, the design reference width of the annealing furnace, and the warning threshold of the second hourly output, the maximum speed limited by the heating capacity of the annealing furnace is calculated using formula (6). ； （6） In formula (6), The maximum speed, measured in m / min, is set to prevent the radiant tube from cracking. The maximum hourly output, t / h, is defined by the critical risk index of the radiant tube under current furnace conditions. The actual thickness of the strip in the heating section, in mm; This refers to the actual width of the strip in the heating section, in mm. It is the density of strip steel, t / m 3 ; The reference width for the annealing furnace design is in mm; This is the production warning threshold for the second hour.

7. The method according to claim 5, characterized in that, To determine the maximum speed required to prevent the radiant tube from cracking, including: Obtain the maximum design speed of the annealing furnace, the setpoint of the annealing temperature in the heating section, the design reference width of the annealing furnace, the actual thickness of the strip in the heating section, and the actual width of the strip in the heating section; Based on the maximum design speed of the annealing furnace, the set value of the annealing temperature of the heating section, the design reference width of the annealing furnace, the actual thickness of the strip steel in the heating section, and the actual width of the strip steel in the heating section, the maximum speed for preventing cracking of the radiant tube is calculated using formula (7). ;（7） In formula (7), The limiting speed of the annealing furnace is given in m / min. The maximum design speed for the annealing furnace is in m / min; This is the setpoint for the annealing temperature of the heating section, in °C; The reference width for the annealing furnace design is in mm; The actual thickness of the strip in the heating section, in mm; This refers to the actual width of the strip in the heating section, in mm. The reference thickness for the annealing furnace design is in mm; The reference thickness for the strip is in mm.

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