Research and development of twin-column periodically counter-current beds packed with metal hydride particles

建立了双柱式氢同位素分离实验装置。通过实验和数值模拟，我们得到了以下结果：(1)通过对氢同位素分离因子、同位素交换反应速率常数和氢解离压力的测量，发现Pd和LaNi_<4.7>Al_<0.3>是最有希望进行同位素分离的材料。两种材料的理论板的等效高度均为0.7cm。(2)利用单一Pd床的置换色谱被证明能够从氢-氘混合物中浓缩高达100%的氘。这一结果直接保证了本文提出的双柱型同位素分离系统的优异性能。(3) Pd中同位素交换传质的速率决定步骤为273K以下的β相扩散和273K以上的孔隙扩散。在LaNi_<5-X>Al_X中，这是沉积在表面的Ni层上的本构同位素交换反应。(4)基于平板理论的数值模拟发现，双人床中建立稳态剖面所需的循环周期在吸附和解吸的100步以内。(5)重新布置实验装置后，从操作时间上看，反流解吸效率更高。(6)全回流条件下的实验结果表明，LaNi_<4.7>Al_<0.3>床层的氘浓度和Pd床层的氘耗尽。该结果保证了双柱式同位素分离系统的效率。

We built an experimental apparatus for the twin-column type of the hydrogen isotope separation. We obtained the following results through experiments and numerical simulations.(1) Pd and LaNi_<4.7>Al_<0.3> were found to be the most promising materials for the isotope separation from measurements of the hydrogen isotope separation factor, the isotopic exchange reaction rate constant and the hydrogen dissociation pressure. The hight equivalent to a theoretical plate was 0.7cm for both of the two materials.(2) The displacement chromatography using a single Pd bed was proved to be able to concentrate up to 100% deuterium from hydrogen-deuterium mixtures. This result directly assures an outstanding performance of the twin-column type isotope separation system proposed here.(3) The rate-determining step for the isotopic exchange mass transfer in Pd was beta-phase diffusion below 273K and pore diffusion above 273K.That in LaNi_<5-X>Al_X was the intrinsic isotopic exchange reaction on a Ni layr deposited on surfaces.(4) The cycles necessary to establish a steady-state profile in the twin beds were found to be within 100 steps of absorption and desorption from numerical simulations based on the plate thory.(5) After rearrangement of the experimental apparatus, desorption with a reversed flow was found to be more efficient from a viewpoint of the operation time.(6) The experimental result under the total reflux condition showed the deuterium concentration in the LaNi_<4.7>Al_<0.3> bed and the deuterium depletion in the Pd bed. This result assures the efficiency of the twin-column type isotope separation system.