Purifying waste gases from nuclear reprocessing plants

摘要

In the purification of waste gases containing nitric oxides, iodine and iodine compounds and triturated water vapour from a nuclear reprocessing plant, hyper-azeotropic nitric acid is introduced at the head (6) of a counter-current gas/liquid contact column (4) and then conducted through a co-current contact column (1) where it is cooled to a temperature of up to -65 DEG C. Waste gas to be purified (22) is introduced into the head of column (1), and thence follows the path (23), (24) and (7). Organic iodine compounds and iodine are partially oxidised, in the cooler lower part of column (1), while in the warmer upper region of column (1) a proportion of the NO oxidised by the hyper-azeotropic nitric acid to NO2. NO2, iodine and water vapour are substantially absorbed by the hyper- azeotropic nitric acid during the subsequent passage through the counter-flow column (4). The flow ratio V=G/F of gas flow G and liquid flow F at any point of the counter-flow column is smaller than the iodine distribution coefficient D (G/F), (c, T), whereby c is the iodine concentration and T the temperature.