A method for predicting converter endpoint temperature based on flue gas analysis
By establishing the relationship between the converter endpoint temperature and the changes in flue gas curve parameters and the oxygen blowing percentage, the converter endpoint temperature can be directly predicted using the flue gas analysis system. This solves the problem of inaccurate prediction in existing technologies, achieving low-cost and rapid temperature prediction, and is applicable to converters of different scales.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HBIS LAOTING STEEL CO LTD
- Filing Date
- 2022-11-07
- Publication Date
- 2026-05-15
AI Technical Summary
Existing technologies cannot accurately predict the converter endpoint temperature, resulting in the need for manual temperature measurement and expensive secondary lance temperature measurement, which increases processing time and costs, and is only applicable to large converters.
By establishing the relationship between the converter endpoint temperature and the changes in flue gas curve parameters and the oxygen blowing percentage, the endpoint temperature can be directly predicted using the flue gas analysis system. The correspondence between the CO% conversion value and the oxygen blowing percentage can be established, and the endpoint temperature can be accurately predicted through formula calculation.
It enables the determination of converter tapping conditions entirely based on the flue gas analysis system, reducing costs and time, and is applicable to temperature prediction for various converter sizes.
Smart Images
Figure CN115935606B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for predicting the final temperature of a converter based on flue gas analysis, belonging to the field of metal smelting technology. Background Technology
[0002] The converter flue gas analysis system is a gas collection and analysis system installed at the top of the converter's inclined flue. By detecting the mass percentages of gases such as CO, CO2, and N2 in the flue gas during the blowing process and plotting and analyzing curves, especially the CO% curve, it can accurately predict the carbon content at the converter's endpoint. However, this system cannot predict the equally important endpoint temperature using existing technology; the temperature calculated using static models often has some deviation.
[0003] The final temperature of the converter is a necessary condition for steelmaking and tapping. Therefore, when using flue gas analysis technology, temperature measurement needs to be carried out simultaneously using methods such as manual temperature measurement and auxiliary lance temperature measurement. "Manual temperature measurement" increases converter processing time and converter temperature loss; "auxiliary lance temperature measurement" uses expensive equipment and probes, and is limited by the size of the converter opening, only suitable for converters with a nominal capacity of 150 tons or more; the problem of predicting temperature restricts the application of flue gas analysis technology. Summary of the Invention
[0004] The purpose of this invention is to provide a method for predicting the final temperature of a converter based on flue gas analysis. This method directly predicts the final temperature by analyzing the relationship between the converter's final temperature and the changes in flue gas curve parameters and the corresponding oxygen blowing percentage. It enables the determination of converter tapping conditions entirely based on the flue gas analysis system, providing a convenient, quick, and low-cost method for predicting the final steel temperature of the converter. This method provides guidance for converter tapping and has application value in steelmaking plants, effectively solving the aforementioned problems in the background technology.
[0005] The technical solution of this invention is: a method for predicting the final temperature of a converter based on flue gas analysis, comprising the following steps: determining the feed rate for the steelmaking process based on the determined raw material conditions, final temperature, carbon content target, etc.; based on the above conditions, establishing a correspondence between the CO% conversion value and the determined oxygen percentage under the determined final temperature conditions, according to the characteristic value of the change in oxygen consumption caused by various factors in the oxygen blowing process due to the final temperature; comparing the CO% conversion value obtained from the CO% curve in the flue gas analysis system in actual production with the standard value and performing relevant calculations to obtain the predicted value of the final temperature; finally, as the final temperature increases, the oxygen percentage corresponding to the CO% conversion point in the flue gas analysis curve decreases.
[0006] The specific steps are as follows:
[0007] Step 1:
[0008] Once the raw materials and feeding conditions are determined, the target CO% conversion value is calculated using the following formula.
[0009] B = (X1 + X2) / (X1 + X2 + X3)
[0010] In the formula, B is the CO% conversion value, X1 is the oxygen consumption in the early stage of blowing, X2 is the oxygen consumption in the middle stage of blowing, and X3 is the oxygen consumption in the later stage of blowing.
[0011] Step 2:
[0012] Obtain actual CO% conversion value B' data during the production process;
[0013] In actual production, when the blowing end point is approached, the target carbon content is predicted by the flue gas system and the total amount of oxygen actually consumed is obtained. This amount of oxygen is the 100% oxygen blowing amount. The actual CO% transition point "B'" is obtained through the CO% process curve.
[0014] Step 3:
[0015] The correlation parameter between the change in CO% transition point and the change in final temperature is β. The actual predicted temperature is obtained by the correlation between the target temperature, the actual temperature and the CO% transition value.
[0016] T_target - T_actual = (BB') × β
[0017] Tactual = Ttarget - (BB') × β.
[0018] The CO% conversion value corresponds to an oxygen blowing percentage range of 65%-85%.
[0019] The correlation parameter between the change in CO% conversion value and the change in the final temperature is β, and the actual CO% conversion value "B'" is obtained through the CO% process curve.
[0020] A fixed target value for the endpoint carbon content is determined as a benchmark for endpoint temperature prediction. The oxygen required for the converter to start blowing until the fixed target value for the endpoint carbon content is reached is 100% oxygen blowing rate.
[0021] The target carbon content is C = 0.03%-0.10%, and the final temperature is T = 1600℃-1700℃.
[0022] The beneficial effects of this invention are: by directly predicting the final temperature of the converter through the relationship between the change of flue gas curve parameters and the corresponding oxygen blowing percentage, the converter tapping conditions can be judged entirely by the flue gas analysis system. This allows for convenient, quick, and low-cost prediction of the final steel temperature of the converter, providing guidance for converter tapping and having application value in steelmaking plants. Attached Figure Description
[0023] Figure 1 This is a graph showing the changes in molten pool temperature, oxygen consumption, and CO% during the oxygen blowing process of this invention.
[0024] In the picture:
[0025] Point A: The transition point between the first and second stages of the molten pool reaction; after this point, the CO reaction becomes independent of temperature.
[0026] Point B: This is the transition point between stage 2 and stage 3. After this point, as the carbon content of the molten pool decreases, the percentage of CO in the flue gas begins to decrease.
[0027] X1: Oxygen consumption in Phase 1
[0028] X2: Oxygen consumption in Phase 2
[0029] X3: Oxygen consumption in stage 3. Detailed Implementation
[0030] To make the purpose, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only a small part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.
[0031] A method for predicting converter endpoint temperature based on flue gas analysis includes the following steps: determining the feed rate for the steelmaking process based on the determined raw material conditions, endpoint temperature, carbon content target, etc.; based on the above conditions, establishing a correspondence between the CO% conversion value and the determined oxygen blowing percentage under the determined endpoint temperature conditions, according to the characteristic values of the change in oxygen consumption caused by various factors in the oxygen blowing process at the endpoint temperature; comparing the CO% conversion value obtained from the CO% curve in the flue gas analysis system in actual production with the standard value and performing relevant calculations to obtain the predicted endpoint temperature value; finally, as the endpoint temperature increases, the oxygen blowing percentage corresponding to the CO% conversion point in the flue gas analysis curve decreases.
[0032] The specific steps are as follows:
[0033] Step 1:
[0034] Once the raw materials and feeding conditions are determined, the target CO% conversion value is calculated using the following formula.
[0035] B = (X1 + X2) / (X1 + X2 + X3)
[0036] In the formula, B is the CO% conversion value, X1 is the oxygen consumption in the early stage of blowing, X2 is the oxygen consumption in the middle stage of blowing, and X3 is the oxygen consumption in the later stage of blowing.
[0037] Step 2:
[0038] Obtain actual CO% conversion value B' data during the production process;
[0039] In actual production, when the blowing end point is approached, the target carbon content is predicted by the flue gas system and the total amount of oxygen actually consumed is obtained. This amount of oxygen is the 100% oxygen blowing amount. The actual CO% transition point "B'" is obtained through the CO% process curve.
[0040] Step 3:
[0041] The correlation parameter between the change in CO% transition point and the change in final temperature is β. The actual predicted temperature is obtained by the correlation between the target temperature, the actual temperature and the CO% transition value.
[0042] T_target - T_actual = (BB') × β
[0043] Tactual = Ttarget - (BB') × β.
[0044] The CO% conversion value corresponds to an oxygen blowing percentage range of 65%-85%.
[0045] The correlation parameter between the change in CO% conversion value and the change in the final temperature is β, and the actual CO% conversion value "B'" is obtained through the CO% process curve.
[0046] A fixed target value for the endpoint carbon content is determined as a benchmark for endpoint temperature prediction. The oxygen required for the converter to start blowing until the fixed target value for the endpoint carbon content is reached is 100% oxygen blowing rate.
[0047] The target carbon content is C = 0.03%-0.10%, and the final temperature is T = 1600℃-1700℃.
[0048] In practical applications, the main reaction in converter oxygen blowing involves the reaction of various elements in the molten pool with the blown oxygen, producing solids that dissolve into the molten pool and generating gases that form flue gas. The main reaction in the converter is decarburization, which produces CO and CO2 gases.
[0049] Oxygen blowing in a converter can be mainly divided into three stages: early, middle, and late, with different reactions in each stage. With fixed feedstock conditions, the reactions in each stage, as well as parameters such as flue gas composition, flue gas composition trends, and oxygen blowing rate, will change accordingly with different final temperatures. By understanding these patterns of change, the difference between the converter's final temperature and the target temperature can be accurately predicted, thus allowing for accurate prediction of the final temperature.
[0050] 1. Main reactions in each stage of oxygen blowing:
[0051] Phase One – Pre-Refining Stage:
[0052] Si + O = SiO2
[0053] C + O = CO↑
[0054] CO + O = CO2↑
[0055] Second stage – Mid-stage of refining:
[0056] C + O = CO↑
[0057] CO + O = CO2↑
[0058] The third stage – the later stage of refining:
[0059] C + O = CO↑
[0060] CO + O = CO2↑
[0061] Fe + O = FeO↑
[0062] The first stage completes the silicon oxidation reaction and fixation; the first stage carbon-oxygen reaction forms CO↑ and CO2↑. Due to the low temperature of the molten pool, the secondary combustion ratio of CO→CO2 is 40%; when the molten pool temperature reaches about 1450℃, the second stage begins. As the temperature increases, the secondary combustion ratio decreases to 10%; after the carbon content of the molten pool decreases to a certain level, the excess O2 is oxidized to CO2, the CO percentage decreases, and the third stage begins until the blowing is completed.
[0063] The point at which the CO% curve of the flue gas reaches a downward inflection point due to a decrease in the carbon content of the molten pool when the molten pool temperature is greater than 1450℃ is called the CO% transition point.
[0064] 2. Argumentation process:
[0065] After the initial conditions such as molten iron, scrap steel, and slag are determined, the changes in molten pool temperature, oxygen consumption, and CO% during oxygen blowing are as follows: Figure 1 As shown:
[0066] Point A: The transition point between the first and second stages of the molten pool reaction; after this point, the CO reaction becomes independent of temperature.
[0067] Point B: This is the transition point between stage 2 and stage 3. After this point, as the carbon content of the molten pool decreases, the percentage of CO in the flue gas begins to decrease.
[0068] X1: Oxygen consumption in Phase 1
[0069] X2: Oxygen consumption in Phase 2
[0070] X3: Oxygen consumption in Phase 3
[0071] First stage: Due to the effect of secondary combustion, more oxygen is consumed when oxidizing the same mass of carbon compared to the last two stages - secondary combustion decreases from 40% to 10%; as the final temperature increases, the carbon content consumed in the first stage decreases, the amount of oxygen consumed X1 decreases, and the amount of oxygen consumed by secondary combustion also decreases.
[0072] Second stage: Oxidation reaction is independent of temperature X2.
[0073] Third stage: As the final temperature rises, the amount of oxygen consumed increases by 3 due to factors such as iron vaporization and increased oxygen in molten steel.
[0074] Therefore, as the final temperature increases, the percentage of oxygen blown at the CO inflection point (X1+X2) / (X1+X2+X3) decreases.
[0075] 3. Judgment process:
[0076] Based on the above discussion, the final temperature can be predicted using the following method.
[0077] A fixed target carbon value is determined as a benchmark for endpoint temperature prediction (a fixed value between 0.03% and 0.10%). The oxygen required for the converter to start blowing until the fixed target carbon content is reached is 100% oxygen blowing rate. Based on the determined raw material conditions and endpoint temperature target, the oxygen blowing percentage corresponding to the target CO% conversion point "B" is determined as (X1+X2) / (X1+X2+X3).
[0078] In actual production, near the end of the blowing process, the target carbon content is predicted by the flue gas system, and the total amount of oxygen actually consumed at this time is obtained. This amount of oxygen is the 100% oxygen blowing rate. The actual CO% transition point "B'" is obtained through the CO% process curve.
[0079] The correlation parameter between the change in CO% conversion point and the change in final temperature is β.
[0080] T_target - T_actual = (BB') × β
[0081] Tactual = Ttarget - (BB') × β.
[0082] The present invention will be further described below with reference to embodiments;
[0083] Example 1
[0084] A 200-ton converter was used, with molten iron containing Si=0.40%, C=4.3%, and T=1340℃; the final target was C=0.03% and T=1700℃. System testing showed that 7000 kg of lime, 3000 kg of lightly calcined dolomite, and 2100 kg of ore were added during the process. The calculated oxygen blowing percentage corresponding to the CO transformation point was B=65%.
[0085] In actual production, the flue gas analysis system determined that the oxygen consumption when the molten pool C=0.03% was 10700 m3, which is the oxygen consumption at 100% oxygen blowing rate. The flue gas analysis curve determined that the oxygen consumption corresponding to the CO transition point was 7169 m3, with a corresponding oxygen blowing percentage of -67% and a correlation coefficient β=-200.
[0086] From the formula Tpredicted = Ttarget - (BB') × β, we can derive Tactual = 1700 - (65% - 67%) × β = 1696℃
[0087] The measured temperature was 1699℃, which is 3℃ lower than the predicted temperature, meeting the prediction requirements.
[0088] Example 2
[0089] A 200-ton converter was used. The molten iron had Si=0.40%, C=4.3%, and T=1300℃. The final target was C=0.06% and T=1650℃. System testing showed that 7000 kg of lime, 3000 kg of dolomite, and 2800 kg of ore were added during the process. The calculated oxygen blowing percentage corresponding to the CO transformation point was B=73%.
[0090] In actual production, the flue gas analysis system determined that the oxygen consumption when the molten pool C=0.06% was 9965 m³. 3 This oxygen consumption is based on 100% oxygen blowing; the oxygen consumption at the CO transition point, determined by flue gas analysis curves, is 6975 m³ / h. 3 The corresponding oxygen blowing percentage is 70%, and the correlation coefficient β = -300.
[0091] From the formula Tactual = Ttarget - (BB') × β, we can derive Tactual = 1650 - (73% - 70%) × β = 1659℃
[0092] The measured temperature was 1657℃, which is 2℃ lower than the predicted temperature, meeting the prediction requirements.
[0093] Example 3
[0094] A 200-ton converter was used. The molten iron had Si=0.40%, C=4.3%, and T=1300℃. The final target was C=0.10% and T=1600℃. System testing showed that 7000 kg of lime, 3000 kg of dolomite, and 5300 kg of ore were added during the process. The calculated oxygen blowing percentage corresponding to the CO transformation point was B=85%.
[0095] In actual production, the flue gas analysis system determined that the oxygen consumption when the molten pool C=0.10% was 9576 m3, which represents 100% oxygen blowing. The flue gas analysis curve indicated that the oxygen consumption at the CO transition point was 7660 m3, corresponding to an oxygen blowing percentage of -80%, with a correlation coefficient β=-400.
[0096] From the formula Tactual = Ttarget - (BB') × β, we can derive Tactual = 1600 - (85% - 80%) × β = 1620℃
[0097] The measured temperature was 1617℃, which is 3℃ lower than the predicted temperature, meeting the prediction requirements.
[0098] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for predicting the final temperature of a converter based on flue gas analysis, characterized in that... The process includes the following steps: determining the feed rate for the steelmaking process based on the established raw material conditions and target conditions for the final temperature and carbon content; establishing a correspondence between the CO% conversion value and the determined oxygen percentage under the determined final temperature conditions, based on the characteristic values of the change in oxygen consumption caused by various factors in the oxygen blowing process at the final temperature, according to the aforementioned raw material conditions and target conditions for the final temperature and carbon content; comparing the CO% conversion value obtained from the CO% curve in the flue gas analysis system in actual production with the standard value and performing relevant calculations to obtain the predicted value of the final temperature; finally, as the final temperature increases, the oxygen percentage corresponding to the CO% conversion value in the flue gas analysis curve decreases. The specific steps are as follows: Step 1: Once the raw materials and feeding conditions are determined, the target CO% conversion value is calculated using the following formula. B = (X1 + X2) / (X1 + X2 + X3) In the formula, B is the CO% conversion value, X1 is the oxygen consumption in the early stage of blowing, X2 is the oxygen consumption in the middle stage of blowing, and X3 is the oxygen consumption in the later stage of blowing. Step 2: Obtain the actual CO% conversion value B' during the production process; In the actual production process, at the end of the blowing process, the target carbon content is predicted by the flue gas system and the total amount of oxygen actually consumed is obtained. This total amount of oxygen is 100% of the oxygen blowing volume. The actual CO% conversion value "B'" is obtained through the CO% process curve. Step 3: The correlation parameter between the change in CO% conversion value and the change in the final temperature is β. The actual predicted temperature is obtained by the correlation between the target temperature, the actual temperature and the CO% conversion value. T_target - T_actual = (BB') × β Tactual = Ttarget - (BB´) × β In the formula, Ttarget is the target temperature, and Tactual is the actual temperature.
2. The method for predicting converter endpoint temperature based on flue gas analysis according to claim 1, characterized in that: The CO% conversion value corresponds to an oxygen blowing percentage range of 65%-85%.
3. The method for predicting converter endpoint temperature based on flue gas analysis according to claim 1, characterized in that: The correlation parameter between the change in CO% conversion value and the change in the final temperature is β, and the actual CO% conversion value "B'" is obtained through the CO% process curve.
4. The method for predicting converter endpoint temperature based on flue gas analysis according to claim 1, characterized in that: A fixed target value for the endpoint carbon content is determined as a benchmark for endpoint temperature prediction. The oxygen required for the converter to start blowing until the fixed target value for the endpoint carbon content is reached is 100% oxygen blowing rate.
5. The method for predicting converter endpoint temperature based on flue gas analysis according to claim 4, characterized in that: The target carbon content is C = 0.03%-0.10%, and the final temperature is T = 1600℃-1700℃.