Method of recovering ammonia from aqueous ammonia vapors by a twostage steam distillation operation

Claim 1

IN A METHOD OF RECOVERING AMMONIA FROM A MIXTURE OF THE VAPOR THEREOF WITH WATER VAPOR, SAID MIXTURE BEING AVAILABLE AT A PRESSURE LOWER THAN THAT WHICH WILL PERMIT CONDENSATION OF THE DESIRED AMMONIA PRODUCT WITH AVAILABLE COOLING WATER, THE STEPS OF INTRODUCING SAID VAPOR MIXTURE INTO A FRACTIONATING TOWER OPERATED AT SUBSTANTIALLY THE SAME PRESSURE, ADMITTING STEAM TO THE BASE OF SAID TOWER AND WITHDRAWING WATER THEREFROM, CONDENSING WITH AVAILABLE COOLING WATER THE OVER HEAD VAPORS FROM SAID FRACTIONING TOWER, SAID OVERHEAD VAPORS HAVING SUBSTANTIALLY THE MAXIMUM AMMONIA CONCENTRATION THAT CAN BE CONDENSED AT THE SAID PRESSURE WITH AVAILABLE COOLING WATER, REFLUXING A PORTION OF THE CONDENSATE AND PUMPING THE REMAINDER OF THE CONDENSATE INTO A SECOND FRACTIONATING TOWER OPERATED AT A SUBSTANTIALLY HIGHER PRESSURE SUCH THAT THE DESIRED AMMONIA PRODUCT IS CONDENSIBLE WITH AVAILABLE COOLING WATER, ADMITTING STEAM TO THE BASE OF SAID SECOND TOWER, AND WITHDRAWING AMMONIA-FREE WATER THEREFROM, CONDENSING THE OVERHEAD VAPOR FROM SAID SECOND TOWER WITH AVAILABLE COOLING WATER, REFLUXING A PORTION OF THE CONDENSATE AND WITHDRAWING THE REMAINDER OF THE CONDENSATE AS THE DESIRED AMMONIA PRODUCT.