Extractive distillation of Nitric Acid (with Sulfuric Acid) is required to be carried out to a higher concentration. In order to obtain virtually water free Nitric Acid from the weak acid it must be distilled in the presence of a extractive agent such as Sulfuric Acid. This displaces the vapour liquid equilibrium of the HNO3-H2O system which reaches an Azeotropic composition so that above a certain proportion of Sulfuric Acid the Azeotrope no longer appears.
ATR-ASAHI is doing the process by indirect heating which results in distinctive advantages:
ATR-ASAHI plants for the production of highly concentrated acid are individually designed, and optimized to suit the duty and the concentration of the weak acid, taking capital costs and operating costs into account.
The packaged columns for concentrating and bleaching are constructed in borosilicate glass in the diameter range DN80 to DN800. Tantalum is used as the material for the column heater, Glass coil heat exchangers and Shell and Tube heat exchangers have proved to be effective for the preheaters, coolers and condensers of plants for the production of highly concentrated acid.
The integral Sulfuric acid re-concentrating unit operates as a vacuum forced-circulation evaporator of the design described in Sulfuric acid concentration plants.
Extensive process know-how add the use of the most up-to-date process controls system make it possible to construct fully automated plants which supply a uniform end product with the minimum expenditure of energy even with fluctuating through puts and acid concentrations.