A control method for setting an air excess coefficient of a two-stage machine of a hot rolling heating furnace

Abstract

The application discloses a kind of control method of hot rolling heating furnace two-stage machine setting air excess coefficient, comprising the following steps: A1: establish the communication connection between primary machine L1 and two-stage machine L2, so that primary machine can receive the air excess coefficient setting of two-stage machine L2;A2: two-stage machine L2 is divided into different heating sections, and the corresponding air excess coefficient setting is determined in each heating section;A3: after slab is put into furnace, slab is identified and judged, and the air excess coefficient setting requirement of slab in each section of heating furnace is determined;A4: according to the determination result of slab, the air excess coefficient setting value of each section of heating furnace is calculated, and the air excess coefficient setting value is sent to primary machine L1;A5: primary machine L1 receives the air excess coefficient setting value sent by two-stage machine L2, controls air-gas ratio, and completes setting.The application can set different air excess coefficients according to the control and adjustment requirements of different steel grades, and improve the adaptability of heating furnace to different steel grades.

Description

Technical Field

[0001] This invention relates to the field of hot rolling control, and in particular to a control method for setting the excess air coefficient in the secondary stage of a hot rolling heating furnace. Background Technology

[0002] The heating furnace is one of the important pieces of equipment in the hot rolling production line. Its function is to heat the steel billet to meet the requirements of alloy solution treatment and subsequent stable rolling. The performance of the heating furnace directly affects the heating quality of the steel billet.

[0003] Among the publicly available documents, patent application number CN202111005386.1 discloses a control system for the furnace temperature, fuel flow rate, air flow rate, and air-fuel ratio of a heating boiler. The control system includes a programmable logic controller (PLC) and field instruments. The PLC is connected to the field instruments. The field instruments include a furnace temperature thermocouple, a fuel flow regulating valve, a fuel flow measuring device, and an air flow orifice plate. The PLC includes a temperature regulator, a fuel flow regulator, a high / low flow alarm (I), a high / low flow alarm (II), a control signal limiter or holder (I), a control signal limiter or holder (II), a range converter (I), a range converter (II), a differential feedforward controller, an air-fuel ratio controller, and an air flow regulator.

[0004] Patent application CN202010363207.0 discloses a method and apparatus for controlling the air-fuel ratio of a pulse-type heating furnace based on flow control. The method includes: dividing the heating furnace into eight control segments; acquiring the measured temperature and set temperature of each pulse control segment; determining the number of burners to be opened in the target pulse control segment based on the measured temperature and set temperature; determining the actual set value of the gas flow rate of the target pulse control segment based on the number of burners opened and the total rated gas flow rate of the target pulse control segment; and determining the actual set value of the air flow rate of the target pulse control segment based on the actual set value of the gas flow rate. By controlling pulse combustion through pipeline pressure, more accurate and rapid response control can be achieved under complex operating conditions such as rapid changes in heat load, fluctuations in gas pressure, and fluctuations in gas calorific value.

[0005] The existing method for controlling the excess air coefficient in heating furnaces is set in the primary stage. However, this method suffers from several drawbacks. First, the calorific value of the mixed gas used fluctuates significantly. Second, with the expansion of product varieties, different atmosphere control requirements arise for different steel strip surface quality. These two factors combined mean that the excess air coefficient setting for each steel variety must be manually controlled by the operator. This places high demands on the operator's skills and workload, and the operator's skill level also impacts the team's fuel consumption control and product surface quality. Therefore, it is necessary to improve this method to overcome these shortcomings. Summary of the Invention

[0006] The purpose of this invention is to provide a control method for setting the excess air coefficient in the secondary stage of a hot rolling heating furnace, which solves the problem that existing methods for controlling the excess air coefficient in heating furnaces are not applicable to the control and adjustment of different steel grades.

[0007] The above-mentioned technical objective of this invention has been achieved by the following technical solutions:

[0008] A method for controlling the excess air coefficient in the secondary stage of a hot rolling heating furnace includes the following steps:

[0009] A1: Establish a communication connection between primary unit L1 and secondary unit L2, enabling primary unit to receive the air excess coefficient setting from secondary unit L2;

[0010] A2: Excess air coefficient setting, dividing the secondary unit L2 into different heating sections, and determining the corresponding excess air coefficient setting for each heating section;

[0011] A3: Slab entry identification and judgment. After the slab enters the furnace, the slab is identified and judged to determine the air excess coefficient setting requirements of the slab in each section of the heating furnace.

[0012] A4: Based on the slab determination results, calculate the air excess coefficient setting value for each section of the heating furnace and send the air excess coefficient setting value to the primary machine L1;

[0013] A5: The primary unit L1 receives the air excess coefficient setting value sent by the secondary unit L2. The primary unit L1 controls the air-gas ratio based on the acquired setting value to complete the setting.

[0014] Step A1 specifically includes the following steps: A11: A communication connection is established between primary machine L1 and secondary machine L2 through a communication interface, integrating primary machine L1 and secondary machine L2 into a communication network to complete data interaction between primary machine L1 and secondary machine L2.

[0015] Step A2 specifically includes the following steps: A21: Divide the secondary machine L2 into a preheating upper section, a preheating lower section, a first heating upper section, a first heating lower section, a second heating upper section, a second heating lower section, a homogenizing upper section, and a homogenizing lower section;

[0016] A22: Preset the excess air coefficient for each heating furnace's preheating upper section, preheating lower section, first heating upper section, first heating lower section, second heating upper section, second heating lower section, soaking upper section, and soaking lower section.

[0017] Step A3 specifically includes the following steps: A31: Identify and determine the steel type of the slab, determine the corresponding steel type of the slab, and determine whether the steel type has any special process requirements. If there are special process requirements, determine the excess air coefficient of each section of the heating furnace according to the special process requirements; if there are no special process requirements, proceed to the next step.

[0018] A32: If there are no special process requirements for the slab, determine whether the slab has quality index requirements. If there are quality index requirements, determine the excess air coefficient of each section of the heating furnace according to the quality index requirements; if there are no quality index requirements, proceed to the next step.

[0019] A33: If there is no quality index requirement for the slab, the excess air coefficient shall be calculated according to the content of each element in the slab.

[0020] Step A4 specifically includes the following steps: A41: Determine the current heating section of the slab, calculate the excess air coefficient based on the different slab weights in the current heating section, and send the calculated excess air coefficient from the secondary machine L2 to the primary machine L1.

[0021] In step A33, the expression for calculating the excess air coefficient based on the carbon, silicon, and aluminum content in the slab is as follows:

[0022] α = 1 + C content × C content control coefficient + SI content × SI content control coefficient + AL content × SI content control coefficient + control coefficient of the segment.

[0023] Step A5 specifically includes the following steps: A51: After obtaining the set value of the excess air coefficient, calculate the corresponding air volume and gas volume, adjust the air and gas ratio in each area of ​​the heating furnace to match the set value, and update the excess air coefficient once every time the slab enters a heating zone.

[0024] In summary, the present invention has the following beneficial effects:

[0025] This method allows for the setting of different excess air coefficients according to the control and adjustment requirements of different steel grades, improving the furnace's adaptability to various steel types. Through precise setting of the secondary unit L2 and real-time control of the primary unit L1, accurate control of the excess air coefficient is achieved, improving combustion efficiency and temperature uniformity. Automated control is also implemented, enhancing production efficiency and ease of operation. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the present invention.

[0027] Figure 2 This is a schematic diagram of the secondary unit. Detailed Implementation

[0028] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to the figures and specific embodiments.

[0029] In existing control technologies, the combustion process between the primary unit (L1) and the secondary unit (L2) is typically controlled by an operator who inputs control parameters through the primary unit (L1) and sends control commands to the secondary unit (L2). The air and gas flow rates within the secondary unit (L2) are then adjusted to control the combustion process. However, the calorific value of the mixed gas fluctuates significantly, and different steel grades have different requirements for the excess air coefficient. Existing control technologies lack a correction mechanism for the excess air coefficient, leading to unstable product quality. This application introduces an excess air coefficient correction mechanism based on furnace operating data and steel type, which can automatically adjust the excess air coefficient to adapt to fluctuations in the calorific value of the mixed gas and the requirements of different steel grades.

[0030] like Figure 1 As shown, the present invention proposes a method for controlling the excess air coefficient in the secondary stage of a hot rolling heating furnace, comprising the following steps:

[0031] A1: Establish a communication connection between primary unit L1 and secondary unit L2, enabling primary unit to receive the air excess coefficient setting from secondary unit L2;

[0032] Step A1 specifically includes the following steps: A11: A communication connection is established between the primary unit L1 and the secondary unit L2 through a communication interface. Preferably, an Ethernet interface is selected as the communication interface between the primary unit L1 and the secondary unit L2. The Ethernet IP address, subnet mask, gateway and other parameters are configured to ensure that the two machines can communicate with each other in the same network segment. The primary unit L1 and the secondary unit L2 are integrated into a communication network to complete the data interaction between the primary unit L1 and the secondary unit L2. This ensures that the air excess coefficient setpoint can be transmitted to the underlying controller in real time and accurately, forming the basis of closed-loop control and providing structural support for subsequent parameter setting and dynamic adjustment.

[0033] The secondary unit L2 calculates the corresponding excess air coefficient based on the furnace's operating data and sends the relevant setpoints to the primary unit L1. Upon receiving the setpoints, the primary unit L1 displays them on the control interface for real-time monitoring and adjustment by the operator. Through data interaction between the primary unit L1 and the secondary unit L2, data processing and decision-making by the secondary unit L2, and display and control functions by the primary unit L1, the entire system achieves a high degree of automation.

[0034] A2: Air excess coefficient setting, determine the corresponding air excess coefficient in each heating section of the secondary unit L2;

[0035] like Figure 2 As shown, step A2 specifically includes the following steps: A21: Divide the secondary machine L2 into a preheating upper section, a preheating lower section, a first heating upper section, a first heating lower section, a second heating upper section, a second heating lower section, a homogenizing upper section, and a homogenizing lower section;

[0036] By dividing the L2 heating stage into multiple heating sections, precise control of each section can be achieved. This division allows for the development of more accurate combustion strategies based on the specific needs and conditions of each heating section, ensuring that each section reaches its optimal combustion state and thus meeting the diverse requirements of different steel production processes.

[0037] A22: Preset the excess air coefficient for each heating furnace's preheating upper section, preheating lower section, first heating upper section, first heating lower section, second heating upper section, second heating lower section, soaking upper section, and soaking lower section.

[0038] Combustion conditions vary across different heating sections due to differences in temperature, pressure, and fuel flow. Therefore, an initial excess air coefficient needs to be preset for each heating section based on its specific characteristics and requirements, and using historical data. During actual operation, operators can adjust and optimize the preset excess air coefficient by observing indicators such as the furnace's combustion status, emissions data, and thermal efficiency.

[0039] The primary unit L1 receives the excess air coefficient setpoint sent by the secondary unit L2 and applies it to the actual combustion control process to achieve more precise automated control and improve production efficiency and product quality.

[0040] A3: Slab entry identification and judgment. After the slab enters the furnace, the secondary machine L2 identifies and judges the slab. Based on the judgment result, the air excess coefficient setting requirements for each section of the heating furnace are determined.

[0041] Step A3 specifically includes the following steps:

[0042] A31: Identify and determine the steel grade of the slab, and determine whether there are any special process requirements for the steel grade. If there are special process requirements, determine the excess air coefficient of each section of the heating furnace according to the special process requirements; if there are no special process requirements, proceed to the next step.

[0043] Step A31 ensures that when the slab has special process requirements, the excess air coefficient of each section of the heating furnace can meet the corresponding requirements, thereby reflecting the specific process objectives.

[0044] The steel grade identification of slabs can be performed using a PDA. The PDA, through its integrated scanning and identification module or by connecting to other sensors, collects the coding or label information on the slab. This information includes key data such as steel grade, batch number, and serial number. The collected data is transmitted to the PDA's processor for decoding, comparison, and analysis. The PDA internally stores a steel grade database containing characteristic information and coding rules for various steel grades. By comparing the collected information with records in the database, the PDA can identify the steel grade of the slab, and the identification result is fed back to the operator in real time or uploaded to the production management system.

[0045] A32: If there are no special process requirements for the slab, determine whether the slab has quality index requirements. If there are quality index requirements, determine the excess air coefficient of each section of the heating furnace according to the quality index requirements; if there are no quality index requirements, proceed to the next step.

[0046] Preferably, the excess air coefficient is calculated based on the content of carbon, silicon, and aluminum elements in the slab, and its expression is as follows: α(segment) = 1 + C content × C content control coefficient + SI content × SI content control coefficient + AL content × SI content control coefficient + segment control coefficient.

[0047] α = 1 + C content × C content control coefficient (75) + SI content × SI content control coefficient (-2.5) + AL content × AL content control coefficient (-0.6) + control coefficient of the section (wherein, the control coefficient of the upper and lower preheating sections is 0.2, the control coefficient of the upper and lower first heating sections is 0.1, the control coefficient of the upper and lower second heating sections is 0.05, and the control coefficient of the upper and lower homogenizing sections is 0.1).

[0048] A4: Based on the judgment result in step A3, set the excess air parameters for each section of the heating furnace;

[0049] Step A4 specifically includes the following steps: A41: Determine the current heating section of the slab, calculate the excess air coefficient based on the different slab weights in the current heating section, and send the calculated excess air coefficient from the secondary machine L2 to the primary machine L1.

[0050] A5: The primary unit L1 receives the air excess coefficient setting value sent by the secondary unit L2. The primary unit L1 controls the air-gas ratio based on the acquired setting value to complete the setting.

[0051] Example 1

[0052] In this embodiment, after the slab enters the heating furnace, the steel type of the slab is determined by a PDA. The steel types include ordinary carbon steel, ordinary silicon steel, oriented silicon steel, high-strength steel, pickled steel, and other major categories.

[0053] After steel grade identification, it is determined whether there are any special process rules for the corresponding steel grade. For example, according to process requirements, a certain type of high-strength steel is identified as 1080DP steel grade, and its excess air coefficient is set as follows: 1.05 for the preheating section, 1.05 for the first heating section, 1.05 for the second heating section, and 1.1 for the soaking section. In the read PDA information, high-strength steel grade identified as 1080DP is uniformly marked, and a relevant key value index is established for the next step of determining the excess air coefficient.

[0054] If the identified steel grade does not have specific process rules, then check whether the corresponding steel grade has quality index rules (steel tapping mark, contract number, quality number, surface control grade parameters). Taking tinplate as an example:

[0055] Step 1: Read the "Tap Mark" field from the PDA information and check if the field contains any of the following values: AQ1060, AQ2460I5, AQ2060, AQ2061; if the tap mark contains any of the above values, the slab is determined to be tin-plated; if the tap mark does not contain any of the above values, the slab is determined not to be tin-plated.

[0056] Step 2: Check the beginning of the contract number. If the steel marking meets the requirements, next check if the first character of the "Contract Number" field is "T" or "I". If the contract number begins with "T" or "I", the slab is determined to be tin-plated; if the contract number does not begin with "T" or "I", the slab is determined not to be tin-plated.

[0057] When the slab is determined to be a tinplate, the excess air coefficient for each section is set according to the process design requirements of tinplate, and the next step of determining the excess air coefficient is carried out.

[0058] If the identified steel grade does not have a quality index specification, a comprehensive calculation is performed based on parameters such as the content of elements like carbon, silicon, and aluminum. The result ensures that each type of steel can be assigned the required excess air coefficient α.

[0059] For example, for a steel tapping mark DT0142D1, with a silicon content of 0.033%, a carbon content of 0.001%, and an aluminum content of 0.054%, the excess air coefficients for each section are set as follows:

[0060] α(preheating upper section and preheating lower section) = 1 + 0.001 × 75 + 0.033 × (-2.5) + 0.054 × (-0.6) + 0.2 = 1.16;

[0061] α(first heating upper section and first heating lower section) = 1 + 0.001 × 75 + 0.033 × (-2.5) + 0.054 × (-0.6) + 0.1 = 1.06;

[0062] α(second heating upper section and second heating lower section) = 1 + 0.001 × 75 + 0.033 × (-2.5) + 0.054 × (-0.6) + 0.05 = 1.01;

[0063] α(Upper and Lower Sections of Soluble Heating) = 1 + 0.001 × 75 + 0.033 × (-2.5) + 0.054 × (-0.6)) + 0.1 = 1.06;

[0064] After the slab enters the heating furnace, the excess air coefficient is set according to the corresponding heating section. If there are slabs with different requirements in the current section, the settings are calculated based on the weight coefficient of the slab and then comprehensively issued. This is updated once per model calculation cycle. The above data is imported into the system's real-time bdb database. Each time the slab moves forward a section after entering the furnace, the data is updated according to the steel type and sent to the primary machine L1 in real time. See the table below:

[0065]

[0066] After implementing the above measures, the automatic input rate of the air excess coefficient setting in the heating process of special steels with air excess coefficient setting requirements has been increased to 99.21%.

[0067] In summary, this solution addresses the problem that existing methods for controlling the excess air coefficient in heating furnaces are not applicable to different steel grades, thus improving the versatility and flexibility of the heating furnace. By precisely controlling the excess air coefficient, combustion efficiency is improved, fuel waste is reduced, temperature distribution within the heating furnace is optimized, and product quality stability is enhanced.

[0068] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "left," and "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. These terms are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, terms such as "set" and "connect" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. In this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, which includes not only the elements listed but also other elements not expressly listed.

[0069] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for controlling the excess air coefficient in the secondary stage of a hot rolling heating furnace, characterized in that, Includes the following steps: A1: Establish a communication connection between primary unit L1 and secondary unit L2, enabling primary unit to receive the air excess coefficient setting from secondary unit L2; A2: Excess air coefficient setting, dividing the secondary unit L2 into different heating sections, and determining the corresponding excess air coefficient setting for each heating section; A3: Slab entry identification and judgment. After the slab enters the furnace, the slab is identified and judged to determine the air excess coefficient setting requirements of the slab in each section of the heating furnace. A4: Based on the slab determination results, calculate the air excess coefficient setting value for each section of the heating furnace and send the air excess coefficient setting value to the primary machine L1; A5: The primary unit L1 receives the air excess coefficient setting value sent by the secondary unit L2. The primary unit L1 controls the air-gas ratio based on the acquired setting value to complete the setting.

2. The method for controlling the excess air coefficient of the secondary stage of a hot rolling heating furnace according to claim 1, characterized in that, Step A1 specifically includes the following steps: A11: A communication connection is established between primary machine L1 and secondary machine L2 through a communication interface, integrating primary machine L1 and secondary machine L2 into a communication network to complete data interaction between primary machine L1 and secondary machine L2.

3. The method for controlling the excess air coefficient of the secondary stage of a hot rolling heating furnace according to claim 1, characterized in that, Step A2 specifically includes the following steps: A21: The secondary machine L2 is divided into an upper preheating section, a lower preheating section, an upper first heating section, a lower first heating section, an upper second heating section, a lower second heating section, an upper homogenizing section, and a lower homogenizing section; A22: Preset the excess air coefficient for each heating furnace's preheating upper section, preheating lower section, first heating upper section, first heating lower section, second heating upper section, second heating lower section, soaking upper section, and soaking lower section.

4. The method for controlling the excess air coefficient of the secondary stage of a hot rolling heating furnace according to claim 1, characterized in that, Step A3 specifically includes the following steps: A31: Identify and determine the steel grade of the slab, and determine whether there are any special process requirements for the steel grade. If there are special process requirements, determine the excess air coefficient of each section of the heating furnace according to the special process requirements; if there are no special process requirements, proceed to the next step. A32: If there are no special process requirements for the slab, determine whether the slab has quality index requirements. If there are quality index requirements, determine the excess air coefficient of each section of the heating furnace according to the quality index requirements; if there are no quality index requirements, proceed to the next step. A33: If there is no quality index requirement for the slab, the excess air coefficient shall be calculated according to the content of each element in the slab.

5. The method for controlling the excess air coefficient of the secondary stage of a hot rolling heating furnace according to claim 1, characterized in that, Step A4 specifically includes the following steps: A41: Determine the current heating section of the slab, calculate the excess air coefficient based on the different slab weights in the current heating section, and send the calculated excess air coefficient to the primary machine L1.

6. The method for controlling the excess air coefficient of the secondary stage of a hot rolling heating furnace according to claim 4, characterized in that, In step A33, the expression for calculating the excess air coefficient based on the carbon, silicon, and aluminum content in the slab is as follows: α = 1 + C content × C content control coefficient + SI content × SI content control coefficient + AL content × SI content control coefficient + control coefficient of the segment.

7. The method for controlling the excess air coefficient of the secondary stage of a hot rolling heating furnace according to claim 1, characterized in that, Step A5 specifically includes the following steps: A51: After obtaining the set value of the excess air coefficient, calculate the corresponding air and gas volume, adjust the air and gas ratio in each zone of the heating furnace to match the set value, and update the excess air coefficient once each time the slab enters a heating zone.

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