A method for smelting stainless steel based on adjusting AOD converter gas supply mode according to CO volume fraction of furnace gas
By monitoring the CO volume fraction in the furnace gas in real time and forming a closed-loop feedback regulation, the gas supply mode is dynamically adjusted, solving the problem of rigid gas supply mode in AOD converter smelting and achieving more efficient chromium recovery and product quality stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN HEAVY EQUIPMENT & TECHNOLOGY CO LTD
- Filing Date
- 2026-04-07
- Publication Date
- 2026-06-12
AI Technical Summary
In existing AOD converter smelting of stainless steel, the control of the gas supply mode is difficult to reflect the real progress of the decarburization reaction in the molten pool in real time, which leads to an increased risk of chromium oxidation, a reduced chromium yield, low resource utilization efficiency, and unstable product quality.
By monitoring the CO volume fraction in the furnace gas in real time, a gas supply flow adjustment command is generated, and a closed-loop feedback regulation is formed to dynamically adjust the gas supply mode and achieve adaptive control of the decarbonization process.
It improves the stability of the smelting process and the efficiency of resource utilization, reduces the risk of chromium oxidation, and enhances the consistency of product quality and the economic benefits of enterprises.
Smart Images
Figure CN122189282A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of AOD converter smelting of stainless steel, and specifically relates to a method for smelting stainless steel by adjusting the gas supply mode of the AOD converter based on the volume fraction of CO in the furnace gas. Background Technology
[0002] An AOD (Argon-Oxygen Decarburization) furnace, also known as an argon-oxygen decarburization refining furnace, is a process in which oxygen and inert gases are mixed according to process requirements and blown into the molten metal pool inside the furnace. This satisfies process requirements such as decarburization, temperature control, and composition control. In the AOD converter smelting of stainless steel, the control of the gas supply mode directly affects decarburization efficiency, chromium yield, and the accuracy of composition control at the smelting endpoint. Traditional AOD smelting typically uses a static gas supply model based on initial process settings. This involves pre-setting the oxygen and inert gas flow rate and ratio curves according to parameters such as steel charge, initial carbon content, and target steel grade. During actual blowing, operators adjust the gas supply parameters periodically based on experience or auxiliary temperature measurements and sampling analysis results. However, due to the high temperature, multiphase reactions, and vigorous stirring of the molten pool involved in the smelting process, the reaction kinetics fluctuate significantly, making it difficult for static models to reflect the actual progress of the decarburization reaction within the molten pool in real time. Especially in the later stages of decarbonization, when the carbon content drops to a low level, the risk of chromium oxidation increases significantly. If the gas supply ratio is not adjusted in time or properly, it can easily lead to a large amount of chromium oxidation, reduce the chromium yield, and increase the consumption of reducing agent and smelting time during the reduction period.
[0003] To address the aforementioned issues, some smelting processes have attempted to incorporate furnace gas composition analysis as a process criterion. The volume fraction of carbon monoxide (CO) in the furnace gas is closely related to the intensity of the carbon-oxygen reaction in the molten pool, indirectly reflecting the kinetic stage of the decarburization reaction. However, current applications are mostly limited to offline analysis or manual experience-based interpretation, and a closed-loop dynamic adjustment mechanism based on CO volume fraction has not yet been established. Adjustments to the gas supply flow rate are still primarily based on phased operations, resulting in low adjustment frequency and delayed response, making it difficult to achieve adaptive control of the decarburization process and the risk of chromium oxidation. Furthermore, subjective differences exist among operators in the execution of gas supply strategies, leading to poor smelting consistency for the same steel grade across different heats, affecting product quality stability and resource utilization efficiency. Summary of the Invention
[0004] To address the aforementioned problems, the purpose of this invention is to provide a method for smelting stainless steel in an AOD converter based on adjusting the CO volume fraction of the furnace gas. This method obtains online monitoring results of the CO volume fraction in the furnace gas, generates a gas supply flow adjustment command based on a preset adjustment strategy, and applies the adjustment command to the gas supply system to achieve gas supply flow adjustment. During the adjustment process, the CO volume fraction information is continuously monitored and the adjustment command is updated, thereby forming a closed-loop feedback adjustment. This changes the current situation of resource waste caused by inconsistent adjustment response, process fluctuations, or control deviations in the existing AOD converter smelting process, which leads to a rigid gas supply mode, and increases the economic benefits of enterprises.
[0005] The technical solution of the present invention is: a method for smelting stainless steel based on adjusting the AOD converter gas supply mode according to the CO volume fraction of the furnace gas, comprising the following steps: Step S1: During the AOD converter smelting process, real-time data on furnace gas composition is collected; Step S2: Analyze the furnace gas composition data to obtain the current real-time volume fraction of carbon monoxide (CO); Step S3: Compare the real-time CO volume fraction with the preset process stage threshold to determine the gas supply mode and generate a gas supply flow rate adjustment command; Step S4: Apply the gas supply flow rate adjustment command to the gas supply system to adjust the gas supply flow rate; Step S5: During the adjustment process, the CO volume fraction is continuously acquired and the gas supply flow adjustment command is updated to form a closed-loop feedback adjustment.
[0006] The AOD converter smelting process is divided into decarburization stage I, decarburization stage II, deep decarburization stage, reduction stage and desulfurization stage according to the carbon content in the molten steel.
[0007] When the CO volume fraction in the furnace gas is greater than 50%, the carbon content in the molten steel is greater than 0.5%, which is considered the decarburization stage I; when the CO volume fraction in the furnace gas decreases to 50%, the carbon content in the molten steel is between 0.2% and 0.5%, which is considered the decarburization stage II; when the CO volume fraction in the furnace gas decreases to 30%, the carbon content in the molten steel is less than 0.2%, which is considered the deep decarburization stage; when the CO volume fraction in the furnace gas decreases to 10%, the carbon content in the molten steel is less than 0.02%, which is considered the reduction stage; when the CO volume fraction in the furnace gas decreases to 5%, it is considered the desulfurization stage.
[0008] During the first stage of decarburization, the molten steel has a high carbon content, leading to preferential decarburization. Oxygen preferentially reacts with carbon and is less likely to oxidize Cr. Therefore, a high oxygen concentration can be used for rapid decarburization. The gas supply mode for this stage is as follows: oxygen intensity is controlled at 1.0-1.3 Nm³. 3 / (t·min), the ratio of oxygen to inert gas supply intensity is controlled at 5:1-10:1; during the second stage of decarburization, the carbon content in the molten steel decreases, and oxygen begins to pose a risk of Cr oxidation, requiring an increase in inert gas to dilute the oxygen partial pressure. The gas supply mode during this period is: oxygen intensity controlled at 0.8-1.2 Nm³. 3 / (t·min), the ratio of oxygen to inert gas supply intensity is controlled at 1:1-3:1; during the deep decarburization period, the carbon content in the molten steel is low and Cr is sensitive to oxidation, so it is necessary to increase the oxygen partial pressure by strongly diluting the inert gas to allow the residual carbon to continue to oxidize, while chromium is basically not further oxidized. The gas supply mode during this period is: oxygen intensity controlled at 0.2-0.4 Nm. 3 / (t·min), the ratio of oxygen to inert gas supply intensity is controlled at 1:2-1:3; during the reduction period, oxygen supply is stopped, and inert gas is blown and stirred + reducing agent is used to reduce Cr2O3, etc., to improve the Cr yield. The gas supply mode during this period is: inert gas intensity controlled at 0.5-1.0 Nm. 3 / (t·min); During the desulfurization period, inert gas is blown for desulfurization to prevent nitrogen absorption. The gas supply mode during this period is: the inert gas intensity is controlled at 0.25-0.5 Nm³. 3 / (t·min).
[0009] The AOD converter uses a side-blowing lance, a central tube for oxygen injection, and an annular slit tube for inert gas injection.
[0010] During the decarbonization phase I, decarbonization phase II, and deep decarbonization phase, the inert gas is nitrogen or argon; during the reduction phase and desulfurization phase, the inert gas is argon.
[0011] The method is applicable to AOD converters ranging from 30 tons to 200 tons.
[0012] The technical advantages of this invention are as follows: By monitoring the CO volume fraction in real time, this invention can accurately determine the decarburization kinetics in the molten pool; by implementing a configurable adjustment strategy, it can achieve dynamic adjustment of the gas supply flow, which can reduce the differences in subjective human adjustment and provide data and control interfaces for process optimization and intelligent control; to a certain extent, it improves the stability of the adjustment process, reduces resource waste, and increases the economic benefits of enterprises.
[0013] The following will provide further explanation in conjunction with the accompanying drawings. Attached Figure Description
[0014] Figure 1 This is a flowchart of a method for smelting stainless steel based on adjusting the AOD converter gas supply mode according to the volume fraction of furnace gas CO.
[0015] Figure 2 This is a graph showing the change in gas supply flow rate with different smelting times according to the present invention. Detailed Implementation
[0016] Example 1 like Figure 1 , Figure 2 As shown, a method for smelting stainless steel using an AOD converter gas supply mode based on adjusting the CO volume fraction of the furnace gas includes the following steps: Step S1: During the AOD converter smelting process, real-time data on furnace gas composition is collected; Step S2: Analyze the furnace gas composition data to obtain the current real-time volume fraction of carbon monoxide (CO); Step S3: Compare the real-time CO volume fraction with the preset process stage threshold to determine the gas supply mode and generate a gas supply flow rate adjustment command; Step S4: Apply the gas supply flow rate adjustment command to the gas supply system to adjust the gas supply flow rate; Step S5: During the adjustment process, the CO volume fraction is continuously acquired and the gas supply flow adjustment command is updated to form a closed-loop feedback adjustment.
[0017] The AOD converter smelting process is divided into decarburization stage I, decarburization stage II, deep decarburization stage, reduction stage and desulfurization stage according to the carbon content in the molten steel.
[0018] When the CO volume fraction in the furnace gas is greater than 50%, the carbon content in the molten steel is greater than 0.5%, which is considered the decarburization stage I; when the CO volume fraction in the furnace gas decreases to 50%, the carbon content in the molten steel is between 0.2% and 0.5%, which is considered the decarburization stage II; when the CO volume fraction in the furnace gas decreases to 30%, the carbon content in the molten steel is less than 0.2%, which is considered the deep decarburization stage; when the CO volume fraction in the furnace gas decreases to 10%, the carbon content in the molten steel is less than 0.02%, which is considered the reduction stage; when the CO volume fraction in the furnace gas decreases to 5%, it is considered the desulfurization stage.
[0019] During the first stage of decarburization, the molten steel has a high carbon content, leading to preferential decarburization. Oxygen preferentially reacts with carbon and is less likely to oxidize Cr. Therefore, a high oxygen concentration can be used for rapid decarburization. The gas supply mode for this stage is as follows: oxygen intensity is controlled at 1.0-1.3 Nm³. 3 / (t·min), the ratio of oxygen to inert gas supply intensity is controlled at 5:1-10:1; during the second stage of decarburization, the carbon content in the molten steel decreases, and oxygen begins to pose a risk of Cr oxidation, requiring an increase in inert gas to dilute the oxygen partial pressure. The gas supply mode during this period is: oxygen intensity controlled at 0.8-1.2 Nm³. 3 / (t·min), the ratio of oxygen to inert gas supply intensity is controlled at 1:1-3:1; during the deep decarburization period, the carbon content in the molten steel is low and Cr is sensitive to oxidation, so it is necessary to increase the oxygen partial pressure by strongly diluting the inert gas to allow the residual carbon to continue to oxidize, while chromium is basically not further oxidized. The gas supply mode during this period is: oxygen intensity controlled at 0.2-0.4 Nm. 3 / (t·min), the ratio of oxygen to inert gas supply intensity is controlled at 1:2-1:3; during the reduction period, oxygen supply is stopped, and inert gas is blown and stirred + reducing agent is used to reduce Cr2O3, etc., to improve the Cr yield. The gas supply mode during this period is: inert gas intensity controlled at 0.5-1.0 Nm. 3 / (t·min); During the desulfurization period, inert gas is blown for desulfurization to prevent nitrogen absorption. The gas supply mode during this period is: the inert gas intensity is controlled at 0.25-0.5 Nm³. 3 / (t·min).
[0020] The AOD converter uses a side-blowing lance, a central tube for oxygen injection, and an annular slit tube for inert gas injection.
[0021] During the decarbonization phase I, decarbonization phase II, and deep decarbonization phase, the inert gas is nitrogen or argon; during the reduction phase and desulfurization phase, the inert gas is argon.
[0022] The method is applicable to AOD converters ranging from 30 tons to 200 tons.
[0023] Example 2 The method for smelting stainless steel using the AOD converter gas supply mode adjusted based on the volume fraction of furnace gas CO as described in Example 1, for smelting 304 austenitic stainless steel; using a 130t AOD converter; the carbon content of the molten steel is 1.7%, including the following steps: Step S1: During the AOD converter smelting process, real-time data on furnace gas composition is collected; Step S2: The furnace gas composition data is analyzed to obtain the current real-time volume fraction of carbon monoxide (CO); Step S3: The real-time CO volume fraction is compared with the preset process stage threshold to generate a gas supply flow adjustment command; Step S4: The adjustment command is applied to the gas supply system to adjust the gas supply flow; Step S5: During the adjustment process, the CO volume fraction is continuously acquired and the adjustment command is updated to form a closed-loop feedback regulation.
[0024] When the CO volume fraction in the furnace gas exceeds 50%, it is determined to be decarbonization stage I; Gas supply mode: Central pipe oxygen flow rate is 150 Nm³. 3 / min, nitrogen flow rate in the circumferential tube is 15 Nm 3 The oxygen to nitrogen ratio is 10:1; when the CO volume fraction in the furnace gas drops to 50% (inclusive), it is considered to be in decarbonization stage II; gas supply mode: oxygen flow rate in the central pipe is 120 Nm³ / min. 3 / min, nitrogen flow rate in the circumferential tube is 40 Nm 3 / min, oxygen to nitrogen ratio is 3:1; when the CO volume fraction in the furnace gas drops to 30% (inclusive), it is determined to be the deep decarbonization period; gas supply mode: the oxygen flow rate of the central pipe is controlled at 40 Nm 3 / min, nitrogen flow rate in the circumferential tube is 120 Nm3 The oxygen to nitrogen ratio is 1:3; when the CO volume fraction in the furnace gas drops to 10% (inclusive), it is determined to be the reduction period; gas supply mode: oxygen supply is stopped, and the argon flow rate in the annular tube is 90 Nm³ / min; when the CO volume fraction in the furnace gas drops to 5% (inclusive), it is determined to be the desulfurization period; gas supply mode: oxygen supply is stopped, and the argon flow rate in the annular tube is 45 Nm³ / min. 3 The gas supply rate was 1 / min, and the steel was tapped after 12 minutes. The tapping temperature of this AOD furnace was 1680℃, with a carbon content of 0.03%, a nickel content of 9%, and a chromium content of 18%.
[0025] Example 3 The method for smelting stainless steel using the AOD converter gas supply mode adjusted based on the volume fraction of furnace gas CO as described in Example 1, for smelting 304L austenitic stainless steel; using a 60t AOD converter; the carbon content of the molten steel is 1.5%, including the following steps: Step S1: During the AOD converter smelting process, real-time data on furnace gas composition is collected; Step S2: The furnace gas composition data is analyzed to obtain the current real-time volume fraction of carbon monoxide (CO); Step S3: The real-time CO volume fraction is compared with the preset process stage threshold to generate a gas supply flow adjustment command; Step S4: The adjustment command is applied to the gas supply system to adjust the gas supply flow; Step S5: During the adjustment process, the CO volume fraction is continuously acquired and the adjustment command is updated to form a closed-loop feedback regulation.
[0026] When the CO volume fraction in the furnace gas exceeds 50%, it is determined to be decarbonization stage I; Gas supply mode: Central pipe oxygen flow rate is 60 Nm³. 3 / min, the argon flow rate in the circumferential tube is 7.5 Nm 3 The oxygen to argon ratio is 8:1; when the CO volume fraction in the furnace gas drops to 50% (inclusive), it is considered to be in decarbonization stage II; gas supply mode: oxygen flow rate in the central pipe is 48 Nm³ / min. 3 / min, argon flow rate in the circumferential tube is 24 Nm 3 / min, oxygen to argon ratio is 2:1; when the CO volume fraction in the furnace gas drops to 30% (inclusive), it is determined to be the deep decarbonization period; gas supply mode: the oxygen flow rate of the central pipe is controlled at 36 Nm 3 / min, argon flow rate in the circumferential tube is 72 Nm 3 The oxygen to argon ratio is 1:2; the reduction period is defined as when the CO volume fraction in the furnace gas drops to 10% (inclusive); gas supply mode: oxygen supply is stopped, and the argon flow rate in the annular slit tube is 60 Nm³ / min. 3 / min; when the CO volume fraction in the furnace gas drops to 5% (inclusive), it is determined to be the desulfurization period; gas supply mode: oxygen supply is stopped, and the argon flow rate in the annular slit pipe is 30 Nm³.3 The gas supply rate is 10 min, and the steel is tapped after 10 minutes. The tapping temperature of this AOD furnace is 1620℃, with a carbon content of 0.2%, a nickel content of 8%, and a chromium content of 18%. After the AOD converter, the molten steel enters the VOD furnace for further processing.
[0027] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for smelting stainless steel based on adjusting the AOD converter gas supply mode according to the CO volume fraction of the furnace gas, characterized in that: Includes the following steps: Step S1: During the AOD converter smelting process, real-time data on furnace gas composition is collected; Step S2: Analyze the furnace gas composition data to obtain the current real-time volume fraction of carbon monoxide (CO); Step S3: Compare the real-time CO volume fraction with the preset process stage threshold to determine the gas supply mode and generate a gas supply flow rate adjustment command; Step S4: Apply the gas supply flow rate adjustment command to the gas supply system to adjust the gas supply flow rate; Step S5: During the adjustment process, the CO volume fraction is continuously acquired and the gas supply flow adjustment command is updated to form a closed-loop feedback adjustment.
2. The method for smelting stainless steel based on adjusting the AOD converter gas supply mode according to claim 1, characterized in that: The AOD converter smelting process is divided into decarburization stage I, decarburization stage II, deep decarburization stage, reduction stage and desulfurization stage according to the carbon content in the molten steel.
3. The method for smelting stainless steel based on adjusting the AOD converter gas supply mode according to claim 2, characterized in that: When the CO volume fraction in the furnace gas is greater than 50%, the carbon content in the molten steel is greater than 0.5%, which is considered the decarburization stage I; when the CO volume fraction in the furnace gas decreases to 50%, the carbon content in the molten steel is between 0.2% and 0.5%, which is considered the decarburization stage II; when the CO volume fraction in the furnace gas decreases to 30%, the carbon content in the molten steel is less than 0.2%, which is considered the deep decarburization stage; when the CO volume fraction in the furnace gas decreases to 10%, the carbon content in the molten steel is less than 0.02%, which is considered the reduction stage; when the CO volume fraction in the furnace gas decreases to 5%, it is considered the desulfurization stage.
4. The method for smelting stainless steel based on adjusting the AOD converter gas supply mode according to claim 3, characterized in that: During the first stage of decarburization, the molten steel has a high carbon content, leading to preferential decarburization. Oxygen preferentially reacts with carbon and is less likely to oxidize Cr. Therefore, a high oxygen concentration can be used for rapid decarburization. The gas supply mode for this stage is as follows: oxygen intensity is controlled at 1.0-1.3 Nm³. 3 / (t·min), the ratio of oxygen to inert gas supply intensity is controlled at 5:1-10:1; during the second stage of decarburization, the carbon content in the molten steel decreases, and oxygen begins to pose a risk of Cr oxidation, requiring an increase in inert gas to dilute the oxygen partial pressure. The gas supply mode during this period is: oxygen intensity controlled at 0.8-1.2 Nm³. 3 / (t·min), the ratio of oxygen to inert gas supply intensity is controlled at 1:1-3:1; during the deep decarburization period, the carbon content in the molten steel is low and Cr is sensitive to oxidation, so it is necessary to increase the oxygen partial pressure by strongly diluting the inert gas to allow the residual carbon to continue to oxidize, while chromium is basically not further oxidized. The gas supply mode during this period is: oxygen intensity controlled at 0.2-0.4 Nm. 3 / (t·min), the ratio of oxygen to inert gas supply intensity is controlled at 1:2-1:3; during the reduction period, oxygen supply is stopped, and inert gas is blown and stirred + reducing agent is used to reduce Cr2O3, etc., to improve the Cr yield. The gas supply mode during this period is: inert gas intensity controlled at 0.5-1.0 Nm. 3 / (t·min); During the desulfurization period, inert gas is blown for desulfurization to prevent nitrogen absorption. The gas supply mode during this period is: the inert gas intensity is controlled at 0.25-0.5 Nm³. 3 / (t·min).
5. The method for smelting stainless steel based on adjusting the AOD converter gas supply mode according to claim 4, characterized in that: The AOD converter uses a side-blowing lance, a central tube for oxygen injection, and an annular slit tube for inert gas injection.
6. The method for smelting stainless steel based on adjusting the AOD converter gas supply mode according to claim 5, characterized in that: During the decarbonization phase I, decarbonization phase II, and deep decarbonization phase, the inert gas is nitrogen or argon; during the reduction phase and desulfurization phase, the inert gas is argon.
7. The method for smelting stainless steel based on adjusting the AOD converter gas supply mode according to claim 6, characterized in that: The method is applicable to AOD converters ranging from 30 tons to 200 tons.