海绵钛生产蒸馏过程中杂质去除机理和动力学研究

Removal of last 5~10% of the volatile impurities wastes the 70% of total distillation period in the vacuum distillation process, which was time and energy intensive. Thus, it's difficult to provide theoretical support and control technology in practical production which aims at removing volatile impurities in the greatest degree. The effects of temperature field distribution, heat transfer characteristics and the structures of the impurities transportation corridor of sponge titanium on the surface distillation rate of the volatile impurities such as magnesium and magnesium chloride in the initial stage and distillation rate and in a capillary hole in the final stage will be discussed in the vacuum distillation process. Besides, we inquire the transport characteristics of volatile impurities in the process of distillation. According to the potential function of the interfaces of the sponge-like pores and the impurities, the thermodynamics and dynamics models of volatile impurities distillation will be established, based on the temperature field distribution of sponge titanium, heat transfer characteristics and the structures of impurities transportation channels. Furthermore, the bottlenecks of distillation kinetics in volatile impurities would be analyzed, the physical and chemical behaviors of volatile impurities in distillation process will also be illuminated. Finally, the removal mechanism of volatile impurities is being explored by the thermodynamics and dynamics models. It provides a theoretical basis and technical approach for the realizations of energy conservation and consumption reduction of high-level sponge titanium by using the Kroll method.

海绵钛真空蒸馏后期5~10%挥发性杂质的去除时间占蒸馏周期的70%，导致蒸馏生产的周期长、能耗高。项目通过研究真空蒸馏过程钛坨温度场分布、传热特性和杂质输运通道结构等因素对镁和氯化镁等挥发性杂质在蒸馏开始阶段的表面蒸馏速率和蒸馏后期的毛细孔内蒸馏速率的影响，研究挥发性杂质在蒸馏过程中的输运特性；利用海绵孔—挥发性杂质界面势函数，建立基于钛坨温度场分布、传热特性和杂质输运通道结构的挥发性杂质蒸馏的热力学和动力学模型，解析挥发性杂质蒸馏动力学的限制性环节，阐明挥发性杂质在蒸馏过程中的物理化学行为；最终依靠建立的热力学和动力学模型阐明挥发性杂质的去除机理，为实现利用Kroll法短流程直接制备高纯海绵钛和蒸馏过程的节能降耗提供理论依据和技术途径。

钛及钛合金广泛应用于航空航天、国防军事、石油化工和临床医疗等领域，是提高国防装备、保障国家战略安全、经济建设和社会发展不可或缺的重要战略物资。海绵钛产量是衡量一个国家钛工业规模的重要指标，中国是全球海绵钛生产能力最大的国家，但工艺技术与生产装备整体水平较低、生产工序能耗较高、缺乏稳定提供航空用海绵钛原料的能力与保障体系。.项目针对镁热法海绵钛生产过程挥发性杂质蒸馏速率慢的问题，通过对海绵钛中可挥发性和非挥发性杂质来源、杂质分布规律等进行了系统的研究，研究了温度场分布、传热特性对Mg和MgCl2蒸馏过程的影响规律，量化了蒸馏过程的能量损失，为蒸馏过程参数的调整提供了依据。基于增广Young-Laplace方程和动力学理论，建立了薄液膜区二维稳态下的流动和蒸发的耦合传热传质模型，根据挥发性杂质去除的热力学模型，建立海绵钛孔中单一流体的蒸发薄液膜区形貌和联合传热模型，研究了过热度、钛坨温度场分布、输运通道特性对Mg和MgCl2熔体薄膜轮廓、蒸发压力、蒸发质量通量和热通量的影响。研究结论和结果为实现利用Kroll法短流程直接制备高纯海绵钛和蒸馏过程的节能降耗、提高生产效率提供理论依据和技术途径。.在项目资助下，共完成发表SCI学术论文9篇，授权国家发明专利3项。培养毕业博士研究生1名、硕士研究生8名。