Abstract: A process for the multi-stage condensation of an overhead fraction is disclosed. The process facilitates optimal response to changes in distillation column controls wherein column top reflux condensation is preferentially returned to said distillation column, but auxiliary surge capacity is obtained by connection to a first accumulator section of an accumulating zone, which surge capacity is supplemented by one-way flow of liquid from a cooler, second section in said accumulation zone.

Abstract: Improved process for the separation of a hydrocarbon-containing feedstream comprising monomer, comonomer and diluent into separate product streams which comprises subjecting the feedstream to two-stage distillation provided with a common accumulation zone wherein the condensate from the accumulation zone serves as the source of feed for the second distillation and reflux for the first distillation. In a specific embodiment, a feed comprising ethylene, 1-hexene, and isobutane is separated into separate streams of 1-hexene, ethylene and isobutane, and isobutane for recycle to polymerization.