Composition control of aqueous ammonia solution by differential pressure

Claim 1

THE PROCESS FOR PREPARING AN AQUEOUS AMMONIA SOLUTION OF CONCENTRATION WITHIN A PREDETERMINED WEIGHT PERCENT RANGE, SAID PROCESS COMPRISING CONTINUOUSLY INTORDUCING AMMONIA INTO THE LOWER SECTION OF AN ABSORPTION ZONE, CONTINUOUSLY INTRODUCING A LIQUID AQUEOUS MEDIUM INTO THE UPPER SECTION OF SAID ABSORPTION ZONE, MAINTAINING A LIQUID LEVEL IN SAID ABSORPTION ZONE ABOVE THE LEVEL OF INTRODUCING SAID AMMONIA AND BELOW THE LEVEL OF INTRODUCING SAID AQUEOUS MEDIUM AS AS TO DIVIDE SAID ABSORPTION ZONE INTO A LIQUID PHASE ZONE AND A VAPOR PHASE ZONE, DETECTING THE DIFFERENTIAL PRESSURE BETWEEN THE VAPOR PRESSURE OF AN AQUEOUS SOLUTION OF AMMONIA OF KNOWN CONCENTRATION SUBMERGED IN SAID LIQUID PHASE AND THE VAPOR PRESSURE OF SAID VAPOR PHASE, REGULATING THE FLOW OF SAID AMMONIA TO SAID ABSORPTION ZONE IN RESPONSE TO CHANGES IN SAID DIFFERENTIAL PRESSURE, CONTACTING SAID INTRODUCED AMMONIA WITH SAID AQUEOUS MEDIUM IN SAID ABSORPTION ZONE, AND CONTINUOUSLY WITHDRAWING RESULTING AQUEOUS AMMONIA SOLUTION FLOW FROM THE BOTTOM OF SAID ABSORPTION ZONE.