Tritium separation performance of adsorption/exchange distillation tower packed with structured packing

Abstract

Separation of tritium from tritiated water is analyzed based on the theoretical plate model comparatively for the three cases among a water distillation tower, the Girdler-Spevack (G-S) bithermal exchange process and the combined electrolysis chemical exchange (CECE) process. The McCabe-Thiele diagrams to design large-scale detritiation systems are drawn for each, and tritium concentration profiles in each system are compared. It is clarified how detritiation behavior in the distillation tower is enhanced by an increase in the separation factor. The number of theoretical stages and internal flow rates to achieve detritiation of the bottom-to-top concentration ratio of xB/xD = 100 in cases of the G-S and CECE processes, are estimated based on the equilibrium stage separation factor reported in the past.A water distillation tower of 108 mm in diameter and 1000 mm in height packed with structured packing coated with Zeolite 13X are experimentally tested for detritiation of a large amount of wastewater to be exhausted from nuclear reactors. Separation performance between HTO and H2O under reduced pressure is experimentally verified in the water distillation tower. Enhancement of the xB/xD ratio is experimentally proved under the total reflux condition as a function of evaporation rate. Activation on surfaces of adsorbent coated on the structured packings enhances the stage separation factor. The enhancement ratio is affected by liquid-gas dispersion in the column and flow instability in the packed tower.