基于ANSYS的冷坩埚感应线圈设计及电磁分析

Design and Electromagnetic Analysis of Induction Coil of Cold Crucible by ANSYS

冷坩埚玻璃固化技术是目前最新一代的高放废液玻璃固化工艺。感应线圈是冷坩埚熔炉的关键部件之一，其设计合理与否直接关系到冷坩埚能否顺利运行。目前世界各国的冷坩埚装置对感应线圈的截面形状、匝数、匝间距等参数采取过不同的设计，对这些设计参数进行计算分析对指导我国冷坩埚研制具有重要意义。本工作基于ANSYS软件对感应线圈的电磁场进行有限元分析，结果表明，加载高频交变电流的感应线圈的电磁场具有以下分布规律：高频电流表现出集肤效应和邻近效应，电流集中于线圈表面，电流密度峰值出现在线圈的最上端和最下端；磁通密度轴向分量（By）在径向上由线圈内边缘附近向线圈包围的中心区衰减，纵向上与电流密度的分布类似，By在线圈上下两端处出现峰值，在线圈高度覆盖的范围之外，磁通密度迅速衰减。本工作进一步结合法国阿海珐公司、美国爱达荷实验室和印度巴巴哈原子能中心的冷坩埚的感应线圈设计方式，建立了不同截面形状、匝数和匝间距的感应线圈模型，经过计算发现矩形截面线圈的磁场分布均匀性要优于圆形截面线圈；在感应线圈总高度相同的前提下，匝数的变化对线圈的磁场分布几乎没有影响；匝间距的增加会降低径向和纵向的磁通密度及其均匀性。综上，建议感应线圈采用密绕型矩形截面设计，匝间距设计为2．5～5mm。

Cold crucible induction melter （CCIM） is one of the most advanced technologies for high-level radio waste liquid vitrification. Induction coil is one of the key assembly of CCIM and its design is a critical factor affecting CCIM operation. Other countries in the world have adapted different designs on the cross-section shape, coil turns and winding space of induction coil. Calculation and analysis on these design parameters are important for the development of CCIM in China. The electromagnetic field of induction coil are analyzed by finite element method based on ANSYS software. Due to skin effect and proximity effect, high frequency current in the induction coil is restricted in the surface and the current density presents two peak values at both top and bottom ends of the coil. Along the radial direction, the axial magnetic flux density （By） decreases gradually from the inner edge of coil to the center region encircled by the coil. Along the vertical direction, similar with the distribution of current density, By also presents two peak values at the two ends of the coil and By decreases rapidly in the region beyond the coil height. Coil models with different cross- section shapes, turns and winding spaces are built and calculated in ANSYS. The results show that coil with rectangular cross-section has a more uniform distribution of magnetic field than coil with circular cross-section. Coils with the same height but different turns have little effect on the magnetic field distribution. By and its uniformity decrease with increasing winding space. According to these results, close-winding coils with rectangular cross-section are recommended for CCIM and the winding space should be 2.5-5 mm.