Fractionator reboiler heat and bottoms product control system

Claim 1

IN A FRACTIONAL DISTILLATION SYSTEM COMPRISING, IN COMBINATION, A FRACTIONAL DISTILLATION COLUMN; MEANS FOR INTRODUCING INTO SAID COLUMN A FLUID MIXTURE TO BE FRACTIONATED; MEANS FOR WITHDRAWING FROM SAID COLUMN AN OVERHEAD FRACTION; MEANS FOR WITHDRAWING FROM SAID COLUMN A BOTTOMS FRACTION; AND MEANS FOR PASSING A HEATING FLUID IN HEAT EXCHANGING RELATIONSHIP WITH THE CONTENTS OF THE KETTLE SECTION OF SAID COLUMN; THE IMPROVEMENT COMPRISING MEANS FOR WITHDRAWING A SAMPLE STREAM OF FLUID FROM A PREDETEMINED POINT IN SAID COLUMN ABOVE THE POINT OF INTRODUCTION OF SAID FLUID MIXTURE TO BE FRACTIONATED, ANALYZING THE THUS WITHDRAWN SAMPLE STREAM AND ESTABLISHING A FIRST SIGNAL REPRESENTATIVE OF THE CONCENTRATION OF A DESIRED HEAVY COMPONENT IN SAID SAMPLE STREAM SUCH THAT AN INCREASE IN THE CONCENTRATION OF SAID DESIRED HEAVY COMPONENT RESULTS IN AN INCREASE IN SAID FIRST SIGNAL, MEANS IN OPERATIVE COMMUNICATION WITH THE KETTLE SECTION OF SAID COLUMN FOR ESTABLISHING A SECOND SIGNAL REPRESENTATIVE OF THE LIQUID LEVEL IN SAID KETTLE SECTION, MEANS RESPONSIVE TO SAID FIRST AND SECOND SIGNALS FOR ESTABLISHING A THIRD SIGNAL REPRESENTATIVE OF SAID SECOND SIGNAL MINUS SAID FIRST SIGNAL SO THAT AN INCREASE IN SAID SECOND SIGNAL CAUSES AN INCREASE IN SAID THIRD SIGNAL WHILE AN INCREASE IN SAID FIRST SIGNAL CAUSES A DECREASE IN SAID THIRD SIGNAL, MEANS RESPONSIVE TO SAID THIRD SIGNAL FOR CONTROLLING THE FLOW OF SAID HEATING FLUID IN HEAT EXCHANGING RELATIONSHIP WITH THE CONTENTS OF THE KETTLE SECTION OF SAID COLUMN SUCH THAT AN INCREASE IN SAID THIRD SIGNAL RESULTS IN AN INCREASE