高碳钢连铸内部质量多目标协调优化与控制研究

The development and quality upgrading of high value-added high carbon are important for improving the competitiveness of iron and steel enterprises. Internal cracks, central shrinkage and segregation are the major defects of high carbon, but in traditional quality control, monomer technology is usually separately adopted to solve one defined defect, the integral quality is hard to properly balanced and coordinated. According to the strong coupling, dynamic and multivariate, multi-objective characteristics in continuous casting process, coordinative optimal control of each monomer control is the key to improve the internal integral quality of casting billets..In this study, based on the preliminary studies for monomer control technologies, the following research works are going to be conducted: the coupled relationship of multi-physics is simplified according analysis of the solidification process, and then a heat-flow-magnetic-quality mechanism model for continuous casting process under mold and final electromagnetic stirring is established and its quick solving method is studied as well. Based on correlation analysis of the relationship between different quality defect indices and various process parameters, mathematical models for internal quality indices are established coupled with before mechanism model. Against with various indices of quality control of high carbon steel, a coordinative optimal system structure with multi-objective is established, which is based on the coupled multi-physics model, and an integral control strategy coupled with adaptive dynamic secondary cooling control based on soft sensor model and case-based reasoning control based on data is proposed as well. Finally, the application study for real-time online control in the casting industrial filed is conducted.

高附加值高碳钢开发和质量升级对钢铁企业提高竞争力具有重要意义，高碳钢的内部裂纹、中心缩孔和偏析是主要缺陷，常规的质量控制往往采用单体技术解决某一确定种类的质量缺陷,综合质量控制难以统筹兼顾和前后协调。针对连铸过程的多场强耦合、强动态、多变量、多目标特点，对各个单体技术进行协调优化控制，是实现铸坯内部综合质量的提高的关键。.本研究拟在前期单体控制技术研究的基础上，通过分析并简化钢水凝固过程多物理场耦合关系，建立在结晶器和凝固末端复合电磁搅拌下的热-流-磁-质连铸坯凝固过程的机理耦合模型，并研究其快速求解方法；基于相关分析法分析各缺陷质量指标与各过程参数的关系，结合机理模型建立内部质量指标判据；建立基于耦合场模型的多目标协调优化体系结构，提出基于软测量模型的自适应动态二冷控制和基于数据的案例推理控制相融合控制策略；最后，进行连铸工业现场的实时在线控制研究。

高碳钢是我国钢铁工业重点发展的高附加值产品，产品开发和质量升级对钢铁企业提高竞争力具有重要意义。高碳钢连铸坯存在的内部裂纹、中心缩孔和偏析等多种缺陷，由于其形成机理各不相同，甚至相悖，单体控制技术难以统筹兼顾产品综合质量。针对连铸过程多场耦合、强动态、多变量、多目标的特点，对各个单体技术进行协调优化控制，是实现铸坯内部综合质量提高的关键。.研究内容按四部分展开：首先，连铸凝固过程多物理场耦合模型的建立与求解。从研究连铸热-流-磁-质四场耦合模型入手，理清各物理场之间的耦合关系，采用相混合统一模型化求解凝固多相变化造成多域建模及其边界跟踪难题，制定了耦合模型的分解建模策略。其次，建立了连铸坯高碳钢内部质量指标模型。基于连铸凝固过程多物理场耦合模型，建立起裂纹判据、缩孔判据和中心偏析判据及其相应集总参数的指标模型。第三，连铸高碳钢内部质量多目标协调优化与控制策略。建立包括铸坯质量多目标协调优化级、优化控制级和基础自动化控制级的三层系统结构。其中作为应对中心偏析缺陷控制的主要环节，对末端电磁搅拌的电流和频率的优化问题展开了研究。最后，工业现场的连铸过程实时在线控制研究。基于非均匀变网格及变时间步长的计算法解决模型的实时性，针对稳态生产和非稳态生产条件提出了控制系统结构和控制算法。.重要结果和意义主要体现在两个方面：一是为目前类似的多物理场耦合模型求解以及多种类缺陷的质量综合控制提供了一条可供参考的思路和研究方法。二是试验证明了该项研究可以较大地提升产品质量。某现场应用6个月效果：65#钢的缩孔缺陷大于1.0级的产品从17%减少到2%，中心偏析大于1.0级的产品从22%减少到7%。.