METHOD FOR LIQUEFYING WASTE PLASTIC

摘要

PROBLEM TO BE SOLVED: To enable a hydrogen chloride gas to be removed efficiently and a high-quality oil to be obtd. SOLUTION: Fluff of a crushed waste plastic is melted with a vented twin- screw extruder E1 and the resultant plastic melt is extruded while a hydrogen chloride gas generated is removed through a vent-hole 5. The extruded waste plastic melt is then introduced into a single-screw extruder E2 , is heated therein to a temp. at which the plastic is liquefied by thermal decomposition. and is extruded. Thus extruded high-temp. waste plastic melt is divided with a flow divider valve 15 into two streams, one of which being returned to the vented twin-screw extruder E1 and the other being introduced into a thermal decomposition vessel 18 to form a liquified gas. The liquified gas is led to a fractional distillation apparatus 24 to be fractionated and recovered and, on the other hand, a part of the high-temp. waste plastic melt in the thermal decomposition vessel 18 is returned to the single-screw extruder E2 .