Continuous extraction of poly-e-caproamide

Claim 1

PROCESS FOR EXTRACTING FROM POLY-E-CAPROMIDE THE HOT WATER-SOLUBLE MATERIALS REMAINING THEREIN AFTER POLYMERIZATION IS COMPLETE, WHICH PROCESS COMPRISES CONTINUOUSLY AND COUNTERCURRENTLY CONTACTING A DOWNWARD MOVING BED OF PARTICLES OF SAID POLY-E-CAPROAMIDE, AT LEAST ONE OF THE DIMENSIONS OF SAID PARTICLES BEING NOT OVER 0.25 INCH, WITH AN UPWARD MOVING BODY OF WATER IN WEIGHT RATIO OF WAER FEED PER HOUR:POLY-E-CAPROAMIDE FEED PER HOUR OF AT LEAST ABOUT 0.8, THEREBY FORMING AN EXTRACTION ZONE CONTAINING AN AQUEOUS EXTRACTION MEDIUM; MAINTAINING THE AVERAGE TEMPERATURE AT THE BOTTOM OF THE EXTRACTION ZONE IN THE RANGE BETWEEN ABOUT 90*C. AND ABOUT 140*C.; SUPPLYING TO SAID MOVING BED OF PARTICLES THE HEAT REQUIRED TO MAINTAIN SAID TEMPERATURE RANGE OF 93*C.-140*C. BY THE HEAT CONTENT OF THE INCOMING WATER AND THUS MAINTAINING A NEGATIVE TEMPERATURE GRADIENT FROM BOTTOM TO TOP OF THE EXTRACTION ZONE AND MAINTAINING TEMPERATURES AT THE TOP THEREOF AT LEAST 5*C. BELOW THE AVERAGE TEMPERATURES AT THE BOTTOM THEREOF; AND MAINTAINING AN ATMOSPHERE OVER THE EXTRACTION ZONE CONSISTING ESSENTIALLY OF VAPORS EVOLVED FROM SAID AQUEOUS EXTRACTION MEDIUM AND OF AN INERT GAS, SAID GAS BEING AT PRESSURE OF AT LEAST 5 P.S.I.; AND THE TOTAL PRESSURE OF SAID ATMOSPHERE OVER THE EXTACTION ZONE PLUS THE HYDROSTATIC PRESSUE DUE TO THE AQUEOUS EXTRACTION MEDIUM THEREIN BEING AT LEAST ABOUT 5 P.S.I. GREATER THAN THE VAPOR PRESSURE EXERTED BY WATER AT THE AVERAGE TEMPERATURE PREVAILING AT THE BOTTOM OF THE EXTRACTION ZONE.