Process and apparatus for segregative drying of nylon-6

Claim 1

A PROCESS FOR SEGREGATIVE DRYING OF NYLON-6 POLYMER PARTICLES WHICH COMPRISES CONTINUOUSLY FEEDING WET NYLON-6 PARTICLES CONTAINING ABOUT 5%-20 BY WEIGHT OF WATER TO THE TOP LAYER OF A CYLINDRICAL BODY OF NYLON-6 PARTICLES IN A DRYING ZONE; CONTINUOUSLY PASSING SAID BODY OF PARTICLES DOWNWARDLY AT A VELOCITY OF NOT ABOVE ABOUT 30 FEET PER HOUR WHILE MAINTAINING SAID BODY IN A SINGLE COMPACT CYLINDRICAL MASS OF CONSTANT DIAMETER AND WITH HEIGHT: DIAMETER RATIO IN THE RANGE 5:1-20-1, TERMINNATING IN A FRUSTO-CONICAL BOTTOM DISCHARGE SECTION WITH SIDES INWARDLY AND DOWNWARDLY SLOPING AT AN ANGLE OF ABOUT 5*-40 FROM THE VERTICAL AND HAVING RATIO OF MAXIMUM:MINIMUM DIAMETER IN THE RANGE OF 3:1-12-1; CONTINUOUSLY PASSING UPWARD THROUGH SAID BODY AN INERT DRYING GAS HAVING A TEMPERATURE IN THE RANGE OF FROM ABOUT 80*C. TO ABOUT 180*C., AS IT FIRST CONTACTS SAID PARTICLES AND BEING AT SUPERATMOSPHERIC PRESSURE NOT LESS THAN ABOUT 10 P.S.I.G., IN AMOUNT OF FROM ABOUT 40 TO ABOUT 140 STANDARD CUBIC FEET OF GAS FOR EACH POUND OF PARTICLES ON A DRY BASIS; MAINTAINING SAID PARTICLES IN CONTACT WITH SAID GAS FOR A TIME OF FROM ABOUT 1 HOUR TO ABOUT 2 DAYS; CONTINUOUSLY REMOVING DRIED PARTICLES AT THE BOTTOM OF SAID CONICAL SECTION; AND WITHDRAWING THE RESULTING MOIST GAS FROM THE TOP LAYER OF SAID CYLINDRICAL BODY OF NYLON-6 PARTICLES.