| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for concentrating/producing heavy nitrogen shortening the time from the operation start of a heavy nitrogen concentration/production apparatus to production ofN of desired concentration.SOLUTION: In the method for concentrating/producing heavy nitrogen using the heavy nitrogen concentration/production apparatus equipped with a reflux column forming nitrogen monoxide gas by the gas-liquid contact reaction of nitric acid aqueous solution with sulfur dioxide gas, and an exchange column concentrating heavy nitrogen in nitric acid by a nitrogen isotope chemical exchange reaction of the nitrogen monoxide gas formed in the reflux column with the nitric acid aqueous solution, the temperature of a part in the reflux column above the interface where the gas-liquid contact reaction of the nitric acid aqueous solution with sulfur dioxide gas occurs is kept at 25°C or more, in the reflux column. |
