Process for the concentration of nitric acid diluted

摘要

22,746. Collett, E. Oct. 30, 1912, [Convention date]. Acids, concentrating.-Dilute nitric acid is concentrated by passage through a series of evaporators 1, 2, 3, from which the vapours are led by pipes 4, 5, 6 to a dephlegmator 7, the nitric acid condensed therein being returned by pipes 9, 10, 11 to the evaporators. The pipes 4, 5, 6 enter the dephlegmator at points 15, 14, 13 corresponding with the concentration of the vapours, the most concentrated entering at the base of the dephlegmator. Dilute acid (about 15-20 per cent) or water is admitted at the top of the dephlegmator by a pipe 18 in order to ensure that aqueous vapour only shall escape by the pipe 12. The acid to be concentrated may be admitted to the dephlegmator by a pipe 19 entering below the pipe 18.