Vacuum Decarburization End-Point Estimation Using Oxygen and CO2 Feedback
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Solution Overview
Problem
Existing methods for determining the decarburization end point in steelmaking processes are inaccurate due to reliance on indirect measurements and lack of utilization of dissolved oxygen concentration and CO gas concentration, leading to potential errors in carbon concentration estimation and incomplete vacuum decarburization treatments.
Innovation Solution
A method and device that estimate carbon concentration and oxygen concentration during vacuum decarburization by using measurement values and a model formula, correcting parameters through Bayesian inference to accurately determine the decarburization end point, utilizing carbon dioxide gas concentration and internal pressure measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If indirect estimation methods are used to determine carbon concentration, then the measurement process is simplified, but the accuracy of carbon concentration estimation deteriorates
Solution Approach 1:
The patent applies feedback by continuously measuring dissolved oxygen concentration and CO gas concentration during vacuum decarburization, then using these measurements to correct the model formula parameters in real-time. This closed-loop approach allows the system to adjust the carbon concentration estimation based on actual process deviations, thereby maintaining high accuracy while using indirect measurement methods.
Solution Approach 2:
The patent replaces direct mechanical carbon concentration measurement (which would require complex sampling and analysis equipment) with a chemical model-based estimation system that uses dissolved oxygen and CO gas concentration measurements. This substitution enables accurate carbon concentration determination through chemical reactions and mathematical models rather than direct physical measurement.
2Measurement precision
If dissolved oxygen concentration is measured sequentially to track carbon concentration changes, then the accuracy of carbon concentration estimation is improved, but the time and labor requirements increase
Solution Approach 1:
The patent merges the measurement of dissolved oxygen concentration with the existing vacuum decarburization process monitoring system. By integrating the dissolved oxygen sensor into the vacuum chamber environment and combining it with CO gas concentration measurement, the system achieves simultaneous tracking of multiple parameters without requiring separate sequential measurement processes, thereby reducing time and labor requirements.
Solution Approach 2:
The patent makes the vacuum chamber monitoring system multi-functional by using it to measure both dissolved oxygen concentration and CO gas concentration simultaneously. This universal approach allows a single integrated system to perform multiple measurement functions that would otherwise require separate dedicated measurement processes, reducing overall time and labor investment.
3Device complexity
If the model formula does not include dissolved oxygen concentration and CO gas concentration, then the model is simpler, but the prediction accuracy of carbon concentration deteriorates
Solution Approach 1:
The patent applies dynamics by making the model formula parameters adjustable and adaptable rather than fixed. The model incorporates dissolved oxygen concentration and CO gas concentration as dynamic variables that can change during the vacuum decarburization process. This allows the model to dynamically adjust to varying process conditions and maintain high prediction accuracy across different operational states.
Solution Approach 2:
The patent changes the parameters of the model formula by incorporating additional variables (dissolved oxygen concentration and CO gas concentration) and making the parameters adjustable based on actual process measurements. This parameter enhancement allows the model to accurately reflect the complex chemical reactions occurring during vacuum decarburization, significantly improving prediction accuracy while maintaining manageable model complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Accurate estimation of carbon concentration and timely determination of the decarburization end point, ensuring stable and precise secondary refining operations and production of high-quality molten steel.
Implementation Method 1
reduction of carbon concentration of molten steel from about 300 ppm to about 100 ppm in a vacuum degassing process
Implementation Method 2
vacuum decarburization treatment for these
Implementation Method 3
measurement values of carbon concentration and oxygen concentration of the molten steel before the vacuum decarburization treatment is started
Implementation Method 4
a mass balance equation of carbon, a decarburization rate, and an in-tank reaction model formula
Implementation Method 5
the carbon concentration of the molten steel is estimated from the dissolved oxygen concentration of the molten steel and the CO gas concentration of exhaust gas
Data Source
AI summary
A decarburization end point determination method includes: estimating the carbon concentration and oxygen concentration of the molten steel and carbon dioxide gas concentration of exhaust gas in the vacuum chamber by using measurement values of the carbon concentration and the oxygen concentration of the molten steel, a measurement value of internal pressure of the vacuum chamber, and a model formula; correcting a parameter included in the model formula to reduce at least one of a difference between an estimate value and a measurement value of the oxygen concentration and a difference between an estimate value and a measurement value of the carbon dioxide gas concentration of the exhaust gas; estimating the carbon concentration of the molten steel by using the model formula in which the parameter is corrected; and determining timing when an estimate value reaches a target value as the completion time point of the vacuum decarburization treatment.