Method and apparatus for controlling polymer deposition in reboiler

Claim 1

IN A PROCESS FOR RECOVERING WASH LIQUID SUBSTANTIALLY FREE OF POLYMER FROM WASHINGS OBTAINED BY WASHING A SOLID OLEFIN POLYMER IN ADMIXTURE WITH SOLUBLE JPOLYMER OF THE SAME OLEFIN AND MONOMER OF SAID OLEFIN COMPRISING THE STEPS OF: (A) FEEDING SAID WASHINGS INTO A FRACTIONAL DISTILLATION COLUMN AND THERE DISTILLING SAME SO AS TO RECOVER AN OVERHEAD VAPOR STREAM OF SAID MONOMER AND LIGHTER MATERIAL IN MINOR AMOUNT, A BOTTOMS LIQUID STREAM OF SAID MONOMER AND SAID SOLUBLE POLYMER OF SUBSTANTIALLY HIGHER POLYMER CONCENTRATION THAN IN SAID WASHINGS, AND A SIDE STREAM OF SAID MONOMER SUBSTANTIALLY FREE OF SAID LIGHT MATERIAL AS THE RECOVERED WASH LIQUID; (B) PASSING A SUBSTANTIAL PORTION OF THE BOTTOMS STREAM OF STEP (A) IN LIQUID FORM THRU INDIRECT HEAT EXCHANGE TUBES OF A REBOILER TO HEAT SAID STREAM AND RETURNING THE HEATED LIQUID STREAM TO THE BOTTOM SECTION OF SAID COLUMN AS REBOIL LIQUID WHEREIN THERE IS A TENDENCY FOR POLYMER TO DEPOSIT IN SAID TUBES; THE IMPROVEMENT COMPRISING: (C) PRIOR TO FEEDING A SUBSTANTIAL PORTION OF THE WASHINGS INTO THE FRACTIONAL DISTILLATION COLUMN ADMIXING THE WASHINGS FEED OF STEP (A) WITH THE BOTTOMS