Process for the manufacture of nitric acid

Claim 1

A PROCESS FOR THE SIMULTANEOUS MANUFACTURE OF NITRIC ACID OF MEDIUM (50 TO 70% BY WEIGHT) AND HIGH CONCENTRATION (80 TO 100% BY WEIGHT) FROM A NITROGEN MONOXIDE CONTAINING GAS DSTREAM ISSUING FROM THE COMBUSTION OF A GAS MIXTURE OF AMMONIA AND AIR WITH A CONTENT OF 12 TO 13% OF AMMONIA IN THE PRESENCE OF CATALYSTS, THE PROCESS COMPRISING A. OXIDIZING THE NITROGEN MONOXIDE IN THE GAS STREAM TO A HIGHER STATE OF OXIDATION BY COUNTERCURRENT FLOW OF NITRIC ACID OF A CONCENTRATION OF 50 TO 70% BY WEIGHT. B. COOLING THE GAS STREAM TO A TEMPERATURE OF APPROXIMATELY 60*C., C. COMPRESSING THE GAS STREAM TO APPROXIMATELY 10 ATM, D. MIXING THE GAS STREAM WITH THE FIRST DEGASSING EFFLUENT OF NITRIC ACID OF 50 TO 70% BY WEIGHT CONCENTRATION, E. COOLING THIS MIXED GAS STREAM IN A FIRST STEP TO APPROXIMATELY 30*C. AND IN A SECOND STEP TO ABOUT 20*C. AND SEPARATING THE CONDENSATE FROM RESIDUAL GASES; F. REACTING THE RESIDUAL GASES FROM THE SECOND COOLING STEP WITH COMPRESSED AIR, WATER, NITRO OXIDE BEARING GAS OF THE FOLLOWING ABSORPTION STEP FOR NITRIC ACID OF HIGH CONCENTRATION AND THE DRAINED AQUEOUS NITRIC ACID FROM THE OXIDATION STEP OF NITROGEN MONOXIDE IN AN ABSORPTION STEP TO FORM NITRIC ACID OF A CONCENTRATION OF 50 TO 70% BY WEIGHT, G. DEGASSING THE NITRO ACID OF MEDIUM CONCENTRATION ONCE AND USING PART OF IT TO OXIDIZE THE NITROGEN MONOXIDE, H. REACTING THE CONDENSATE FROM THE TWO COOLING STEPS OF (E) WITH THE BOTTOM PRODUCT OF ABOUT AZEOTRAPIC CONCENTRATION OF THE DISTILLATION STEP (1) FOR NITRIC ACID OF HIGH CONCENTRATION UP TO 90% BY WEIGHT, AND I. DISTILLING THE EFFLUENT FROM THE ABSORPTION STEP (H) IN NITRIC ACID OF HIGH CONCENTRATION (MORE THAN 90% BY WEIGHT) AND IN A BOTTOM PRODUCT OF ABOUT AZEOTROPIC CONCENTRATION.