Recovery of para xylene by crystallization

Claim 1

A PROCESS FOR SEPARATING PARAXYLENE FROM A FEED STOCK CONSISTING OF A LIQUID MIXTURE OF HYDROCARBONS INCLUDING PARAXYLENE IN THE RANGE FROM ABOUT 12 TO 25% BY VOLUME AND AT LEAST ONE OTHER ISOMERIC XYLENE AND HAVING A EUTECTIC POINT OF PARAXYLENE WITH THE NEXT MOST EASILY PRECIPITATED COMPONENT IN THE NEIGHBORHOOD OF -98*F, WHICH COMPRISES THE STEPS OF FORMING FROM SAID FEED STOCK A BODY OF SLURRY CONSISTING OF PARAXYLENE CRYSTALS AND MOTHER LIQUOR MAINTAINED AT A TEMPERATURE APPROXIMATELY AT BUT NOT BELOW SAID EUTECTIC POINT, FORMING A FIRST STREAM OF CHILLED FEED STOCK AND INTRODUCING SAID FIRST STREAM INTO SAID BODY OF SLURRY, SAID BODY OF SLURRY BEING MAINTAINED AT APPROXIMATELY SAID EUTECTIC TEMPERATURE BY WITHDRAWING FROM SAID BODY OF SLURRY A SECOND STREAM CONSISTING OF PARAXYLENE CRYSTALS AND MOTHER LIQUOR, CHILLING SAID SECOND STREAM IN A SCRAPED SURFACE CHILLER AT A VELOCITY WITHIN THE RANGE OF 100 TO 600 FEET PER MINUTE WITH A RESIDENSE TIME NOT OVER APPROXIMATELY 30 SECONDS AT A TEMPERATURE BELOW BUT NOT MORE THAN 3*F, BELOW THE TEMPERATURE OF THE BODY OF THE SLURRY AND SAID EUTECTIC POINT WHEREBY THE HEAT TRANSFER COEFFICIENT OF SAID SECOND STREAM IS INCREASED, RETURNING A SUFFICIENT AMOUNT OF SAID CHILLED SECOND STREAM TO SAID BODY OF SLURRY, AND THEN PASSING SLURRY CONSISTING OF CRYSTALS AND MOTHER LIQUOR WHICH HAS BEEN WITHDRAWN FROM SAID BODY OF SLURRY TO A CENTRIFUGE AND THERE SEPARATING A PARAXYLENE FILTER CAKE AS PRODUCT.