Application of sidestream recycle to the separation of hydrogen isotopes by cryogenic distillation

Withdrawal of a sidestream from an isotopic separation distillation column followed by equilibration of species and reinjection is a technique for reducing the required number of columns and hence reducing tritium inventories in fusion-energy fuel processing systems. Measurements have been made with a single column and the three-component H/sub 2/-HD-D/sub 2/ system withdrawing streams of essentially pure H/sub 2/ and D/sub 2/. This was followed by single column measurements with the full HDT system and a column inventory of ca 16.8 moles (H/D/T=0.043/0.528/0.429). Rather pure T/sub 2/ (ca. 98.7 mol%) was produced as one of the products. This would previously have required two separate distillation columns with an inventory of ca. 16 moles of T/sub 2/ as compared with 7.2 moles of T/sub 2/ in these experiments. The dynamic response of the H-D system was followed using in situ laser Raman spectroscopy to obtain product compositions and column composition profiles.