| The burden distribution in the blast furnace(BF)has a great influence on ironmaking production.Reasonable operation of furnace charging is beneficial to gas flow distribution improvement in the furnace,which is helpful to stabilize the furnace conditions,improve the gas utilization efficiency and reduce the fuel ratio.In the process of burden distribution with bell-less top,for the difficulty to obtain a steady and satisfying ratio of ore to coke and reasonable burden surface by manual decisions,it is unable to adjust the burden distribution control timely and accurately once the furnace conditions worsen.Therefore,in order to adjust the BF production state to the best,it is of practical significance to research the furnace charging process which contains burden distribution behavior analysis,the pattern recognition of gas flow distribution,the forecast of BF state development and the optimal control strategy of the burden distribution operation.In order to have a good knowledge of the burden distribution behaviors in the BF,the burden motion in the BF charging system was studied using the method of numerical simulation and experimental verification.The influence of the burden motion on the heap formation was analyzed,and the heap profile was constructed by two straight lines and a polynomial curve.On the basis of the above research,the method which was suitable for the prediction of burden distribution whose radius of burden distribution and mass flow rate were varying during furnace charging was put forward,and the mathematical model of burden surface prediction for both ring charging and spiral charging was established,which layed a solid foundation for burden distribution control.The non-contact burden surface measuring technology was applied to measure the burden surface and its descent.The non-uniform burden descent in the BF was investigated,and the method for calculating the ratio of ore to coke was obtained by estimating the shape and position of the burden layer.The burden surface and the ratio of ore to coke were selected as the main control parameters in the process of burden distribution operation.In order to obtain the expected burden surface and the ratio of ore to coke,a mathematical model of conventional ring charging control based on improved genetic algorithm was established,and mathematical models of stepping ring charging and spiral charging control based on social emotional optimization algorithm were proposed,respectively.Burden distribution error and burden layer thickness uneven rate were applied as two quantitative indictors to evaluate the accuracy of burden distribution.The influence of the process parameters on the burden distribution error was analyzed,and effects of burden distribution by the stepping ring charging and the spiral charging were compared with the conventional ring charging to explore their internal relations.The variation of burden layer thickness uneven rate in spiral charging was studied,and the measure to reduce the circumferential unevenness of burden distribution was put forward.The gas flow distribution was classified into four types,and a mathematical model of gas flow distribution pattern recognition based on learning vector quantization neural network was established according to the real-time measured data of BF.The comprehensive evaluation index of BF production considering the stability of furnace state,economic benefit,product quality and BF life was established.The multi-scale wavelet decomposition was used to remove the signal noise of the technical indicators,and the support vector machine was used to predict the tendency of the technical indicators under different burden distribution controls.The burden distribution operation adjustment strategy to achieve optimal control of BF production was proposed based on the pattern recognition results of gas flow distribution.This model was verified off-line and simulated in Ansteel Group No.4 BF. |
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