Control system for nitric acid plant

Claim 1

IN A PLANT PRODUCING NITRIC ACID INCLUDING A CATALYTIC AMMONIA OXIDIZER, A CONDUIT SUPPLYING AMMONIA TO SAID AMMONIA OXIDIZER, A CONDUIT SUPPLYING AIR TO SAID AMMONIA OXIDIZER, MEANS FOR ADDING HEAT TO THE AIR IN SAID CONDUIT, AN ABSORPTION COLUMN, MEANS FOR SUPPLYING WATER TO SAID ABSORPTION COLUMN, MEANS FOR SUPPLYING THE AMMONIA OXIDIZER EFFLUENT AND ADDITIONAL AIR TO SAID ABSORPTION COLUMN, AND A CONDUIT FOR REMOVING NITRIC ACID FROM SAID ABSORPTION COLUMN, AND IMPROVED CONTROL SYSTEMM WHICH COMPRISES, IN COMBINATION, A FIRST ANALYZER MEANS OPERATIVELY CONNECTED TO SAID CONDUITS FOR SUPPLYING AMMONIA AND AIR TO THE AMMONIA OXIDIZER SO AS TO DETERMINE THE RATIO OF AMMONIA TO AIR PASSING TO SAID AMMONIA OXIDIZER; A RATIO CONTROLLER OPERATIVELY CONNECTED TO SAID FIRST ANALYZER AND TO SAID AMMONIA CONDUIT TO CONTROL THE FLOW OF AMMONIA IN RESPONE TO A SIGNAL FROM SAID ANALYZER; A SECOND ANALYZER MEANS OPERATIVELY CONNECTED TO THE EFFLUENT FROM SAID AMMONIA OXIDIZER TO DETERMINE THE NITROGEN OXIDE CONTENT OF SAID EFFLUENT; A CATALYST EFFICIENCY COMPUTER OPERATIVELY CONNECTED TO SAID FIRST AND SECOND ANALYZERS TO COMARE THE SIGNALS FROM SAID ANALYZERS AND TO PRODUCE A SIGNAL INDICATIVE OF THE EFFICIENCY OF SAID CATALYST IN SAID AMMONIA OXIDIZER; OPTIMIZING CONTROLLER MEANS; MEANS OPERATIVELY CONNECTED TO SAID OPTIMIZING CONTROLLEER, TO SAID CATALYST EFFICIENCY COMPUTER AND TO SAID RATIO CONTROLLER TO PERIODICALLY ADJUSTED THE QUANTITY OF AMMONIA PASSING TO SAID