Extractive distillation control

Claim 1

IN AN EXTRACTIVE DISTILLATION COLUMN WHEREIN A FEED MIXTURE TO BE SEPARATED IS INTRODUCED INTO THE COLUMN THROUGH FIRST CONDUIT MEANS, A KETTLE PRODUCT IS WITHDRAWN FROM THE COLUMN THROUGH SECOND CONDUIT MEANS, VAPOR IS REMOVED FROM THE TOP OF THE COLUMN THROUGH THRID CONDUIT MEANS AND COOLED TO CONDENSE AT LEAST A PART THEREOF, A PART OF THE CONDENSED VAPOR IS RETURNED TO THE COLUMN THROUGH FOURTH CONDUIT MEANS AS REFLUX, AND A SOLVENT IS INTRODUCED INTO THE COLUMN THROUGH FIFTH CONDUIT MEANS; A CONTROL SYSTEM COMPRISING MEANS TO ESTABLISH A FIRST SIGNAL REPRESENTATIVE OF THE RATE OF FLOW OF SOLVENT TRHOUGH SAID FIFTH CONDUIT MEANS; MEANS TO ESTABLISH A SECOND SIGNAL REPRESENTATIVE OF THE QUANTITY (KAT), WHERE K IS A CONSTANT AND *T IS THE TEMPERATURE DIFFERENCE BETWEEN SOLVENT INTRODUCED INTO THE COLUMN THROUGH SAID FIFTH CONDUIT MEANS AND VAPOR IN THE COLUMN ADJACENT THE POINT OF INTRODUCTION OF SOLVENT; MEANS TO MULTIPLY SAID FIRST AND SECOND SIGNALS TO ESTABLISH A THIRD SIGNAL; AND MEANS RESPONSIVE TO SAID THIRD SIGNAL TO CONTROL THE FLOW THROUGH SAID FOURTH CONDUIT MEANS.