Control of a distillation column with plural heating media

Claim 1

A METHOD FOR OPERATING A FRACTIONAL DISTILLATION ZONE WHEREIN FEED AND REFLUX ARE ITRODUCED INTO SAID ZONE SUBSTANTIALLY CONSTANT RATES AND HEAT EXCHANGE MEDIUMS SUPPLY REBOILING HEAT TO THE LIQUID KETTLE CONTENTS OF SAID ZONE COMPRISING PROVIDING ONE PORTION OF THE REBOILING HEAT FOR SAID ZONE BY PASSING A HOT HEAT EXCHANGE LIQUID IN INDIRECT HEAT EXCHANGE WITHLIQUID KETTLE CONTENTS OF SAI ZONE, SENSING A TEMPERATURE DIFFERENCE OF SAID HEAT EXCHANGE LIQUID ON PASSING THROUGH SAID INDIRECT HEAT EXCHANGE, DETERMINING THE FLOW RATE OF SAID HEAT EXCHANGE LIQUID, MULTIPLYING SAID FLOW RATE BY THE SENSED TEMPERATURE DIFFERENCE AND BY THE SPECIFIC HEAT OF SAID HEAT EXCHANGE LIQUID AND THEREBY OBTAINING THE HEATING VALUE ADDED TO SAID KETTLE CONTENTS OF SAID ZONE, PROVIDING THE REMAINING PORTION OF THE REBOILING HEAT FOR SAID ZONE BY CONDENSING STEAM IN INDIRECT HEAT EXCHANGE WITH LIQUID KETTLE CONTENTS OF SAID ZONE, DETERMINING THE RATE OF FLOW OF SAID STEAM, ADDING A SIGNAL PROPORTIONAL TO SAID HEATING VALUE ADDED TO SAID KETTLE CONTENTS TO A SIGNAL PROPORTIONAL TO THE RATE OF FLOW OF SAID STEAM TO OBTAIN A SIGNAL PROPORTIONAL TO THE SUM THEREOF, CONTROLLING THE RATES OF FLOW OF SAID HEAT EXCHANGE LIQUID AND SAID STEAM RESPONSIVE TO SAID SIGNAL PROPORTIONAL TO THE SUM IN SUCH A MANNER THAT SAID HEAT EXCHANGE LIQUID FLOWS AT ITS MAXIMUM RATE PRIOR TO PASSAGE OF SAID STEAM IN ITS HEAT EXCHANGE FLOW, WITHDRAWING A SAMPLE OF FLUID IN PROCESS FRM A SELECTED CONTROL POINT OF SAID ZONE, ANALYZING THE WITHDRAWN FLUID FOR CONTENT OF A KEY COMPONENT, AND FURTHER REGULATING THE FLOW OF SAID HEAT EXCHANGE LIQUID AND THE FLOW OF SAID STEAM IN RESPONSE TO SAID CONTENT OF SAID KEY COMPONENT.

Claim 2

A METHOD FOR OPERATING A FRACTIONAL DISTILLATION ZONE WHEREIN FEED AND REFLUX ARE ITRODUCED INTO SAID ZONE SUBSTANTIALLY CONSTANT RATES AND HEAT EXCHANGE MEDIUMS SUPPLY REBOILING HEAT TO THE LIQUID KETTLE CONTENTS OF SAID ZONE COMPRISING PROVIDING ONE PORTION OF THE REBOILING HEAT FOR SAID ZONE BY PASSING A HOT HEAT EXCHANGE LIQUID IN INDIRECT HEAT EXCHANGE WITHLIQUID KETTLE CONTENTS OF SAI ZONE, SENSING A TEMPERATURE DIFFERENCE OF SAID HEAT EXCHANGE LIQUID ON PASSING THROUGH SAID INDIRECT HEAT EXCHANGE, DETERMINING THE FLOW RATE OF SAID HEAT EXCHANGE LIQUID, MULTIPLYING SAID FLOW RATE BY THE SENSED TEMPERATURE DIFFERENCE AND BY THE SPECIFIC HEAT OF SAID HEAT EXCHANGE LIQUID AND THEREBY OBTAINING THE HEATING VALUE ADDED TO SAID KETTLE CONTENTS OF SAID ZONE, PROVIDING THE REMAINING PORTION OF THE REBOILING HEAT FOR SAID ZONE BY CONDENSING STEAM IN INDIRECT HEAT EXCHANGE WITH LIQUID KETTLE CONTENTS OF SAID ZONE, DETERMINING THE RATE OF FLOW OF SAID STEAM, ADDING A SIGNAL PROPORTIONAL TO SAID HEATING VALUE ADDED TO SAID KETTLE CONTENTS TO A SIGNAL PROPORTIONAL TO THE RATE OF FLOW OF SAID STEAM TO OBTAIN A SIGNAL PROPORTIONAL TO THE SUM THEREOF, CONTROLLING THE RATES OF FLOW OF SAID HEAT EXCHANGE LIQUID AND SAID STEAM RESPONSIVE TO SAID SIGNAL PROPORTIONAL TO THE SUM IN SUCH A MANNER THAT SAID HEAT EXCHANGE LIQUID FLOWS AT ITS MAXIMUM RATE PRIOR TO PASSAGE OF SAID STEAM IN ITS HEAT EXCHANGE FLOW, WITHDRAWING A SAMPLE OF FLUID IN PROCESS FRM A SELECTED CONTROL POINT OF SAID ZONE, ANALYZING THE WITHDRAWN FLUID FOR CONTENT OF A KEY COMPONENT, AND FURTHER REGULATING THE FLOW OF SAID HEAT EXCHANGE LIQUID AND THE FLOW OF SAID STEAM IN RESPONSE TO SAID CONTENT OF SAID KEY COMPONENT.