METHOD OF RECOLLECTING NITROGEN TRIFLUORIDE

摘要

PROBLEM TO BE SOLVED: To provide a method of recollecting nitrogen trifluoride safely and economically from a multi-component fluid through a continuous distillation which is more friendly to the environment than a batch distillation. SOLUTION: This method of recollecting nitrogen trifluoride employs a first distillation column 103 and a second distillation column 109 both of which have a top section and a bottom section respectively and comprises the steps of feeding a multi-component fluid 101 to the first distillation column at a first feeding part down the top section, feeding a low temperature liquid 115 to either of the first or the second distillation column at a part adjoining the top section, taking out a mixture 107 containing NF3 from the first distillation column, feeding the mixture to the second distillation column at a second feeding part, separating NF3 from the mixture at the second distillation column, and taking out the NF3 stream 111 from the second distillation column.