Abstract:

¹⁰B is an extremely important stable isotope with a strong ability to absorb neutrons, and thus is widely used in the nuclear power field. The chemical exchange method is commonly used in industry to produce ¹⁰B, but this method has problems such as low output, high toxicity of complexing agents, and severe equipment corrosion. In contrast, the low-temperature distillation method has the technical advantages of high output, no pollution, and stable operation. To meet the large demand for high-abundance ¹⁰B products in nuclear power development, the research and development of the low-temperature distillation method for producing ¹⁰B can increase output while reducing equipment corrosion, which has considerable economic value. This paper, in combination with the pilot-scale test of boron isotope separation by low-temperature distillation at the China Institute of Atomic Energy, used the classic chemical engineering simulation software Aspen Plus to simulate the process of separating ¹⁰BF₃ and ¹¹BF₃ isotopes in a two-column cascade low-temperature distillation tower. Through calculation, the physical property parameters of BF₃ isotopic compounds were obtained, and a process model for boron isotope separation was established. Two physical property methods, IDEAL and PR, were used for simulation. Among them, the PR equation of state method corrected the non-ideality of the gas phase and the interaction in the liquid phase, and its simulation results (error 3.04%) were significantly better than the ideal model (8.99%). The simulation results showed that reducing the operating pressure, decreasing the feed rate, increasing the reflux ratio and the number of theoretical plates could all increase the abundance of the bottom product, among which increasing the number of theoretical plates had a more significant effect on the abundance improvement. The research results of this paper could provide theoretical guidance for the subsequent industrial production of ¹⁰B isotopes.

Key words: cryogenic distillation, boron isotope, Aspen Plus, separation, computer simulation, vapor liquid equilibrium

摘要：

¹⁰B是一种极为重要的稳定同位素，具有很强的吸收中子能力，因此其在核电领域应用广泛。工业上普遍采用化学交换法生产¹⁰B，但该方法存在产量低、络合剂毒性大、设备腐蚀严重等问题，而低温精馏法具有产量高、无污染、运行稳定的技术优势。为了满足核电发展对高丰度¹⁰B产品的大量需求，研究开发低温精馏法生产¹⁰B的工艺能够在提高产量的同时减少对设备的腐蚀，具有可观的经济价值。本文结合中国原子能科学研究院低温精馏法分离硼同位素的中试实验，采用经典化工模拟软件Aspen Plus模拟二塔级联的低温精馏塔分离¹⁰BF₃和¹¹BF₃同位素体系的过程，经过计算获得了BF₃同位素化合物的物性参数，建立了硼同位素分离的工艺模型。采用理想（IDEAL）和Peng-Robinson（PR）两种物性方法进行模拟，其中PR状态方程法修正了气相非理想性和液相相互作用，其模拟结果（误差3.04%）显著优于理性模型（误差8.99%）。模拟结果表明，降低操作压力、减小出料量、增加回流比和理论塔板数均可以增大塔底产品丰度，其中增加理论塔板数对丰度的提升效果更显著。本文的研究结果可以为后续¹⁰B同位素工业化生产提供理论指导。

关键词: 低温精馏法, 硼同位素, Aspen Plus, 分离, 计算机模拟, 气液平衡