Abstract:Good quality of molten iron is the guarantee for the reliability and stability of cast iron performance. The contents of sulfur (S) and silicon (Si) in molten iron are main indicators to measure the quality of molten iron. Therefore, the accurate determination of S and Si contents in molten iron before tapping is of great significance. A method for predicting the S and Si contents in molten iron by combining principal component analysis (PCA) with least squares support vector machine (LS-SVM) model was proposed. The online data of large blast furnace collected in a steel plant was used as the research object. Firstly, PCA was performed on the data that influencing the changes of S content and Si content in molten iron. The principal component was obtained for the input variable of model. Secondly, the LS-SVM model was established to predict the S content and Si content in molten iron. During the prediction process of S content, the prediction error was minimal when the regularization parameter (gam) and kernel function parameter (sig) was 20 and 700, respectively. Meanwhile, the root mean square error was 0.0012, and the simulation time was 0.423105 s. During the prediction process of Si content, the prediction error was minimal when gam and sig was 40 and 500, respectively. Meanwhile, the root mean square error was 0.0238, and the simulation time was 0.079522s. Finally, the experimental results were compared with the traditional LS-SVM model and PCA+BP model (PCA combined with back-propagation neural network). For the prediction of S content in traditional LS-SVM model and PCA+BP model, the root mean square error was 0.0015 and 0.0014, and the simulation time was 1.320842s and 2.245967s, respectively. For the prediction of Si content in traditional LS-SVM model and PCA+BP model, the root mean square error was 0.0316 and 0.0325, and the simulation time was 0.459671s and 2.061576s, respectively. The experimental results showed that the proposed method could more fully consider the influence of all factors on the change of S content and Si content in molten iron. This method exhibited the advantages such as short training time and high prediction accuracy.
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ZHAO Ning, WANG Yu-ying, YANG Fan, YANG Wei-xuan. Application of principal component analysis and least squaressupport vector machine model in prediction of sulfurand silicon content in molten iron. , 2020, 40(2): 1-6.
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