entrained particulates auxiliary heat to impart an additional quantity of heat to the polymerization effluent is supplied by appropriate heating means during the transit between the discharge valve and the first flash tank after removal of the fines the isobutane vapor is condensed without compression by heat exchange at a pressure of about 240 psia and a temperature of about 135 u00b0 f the polymer slurry solids discharging from the bottom of the first flash tank into the seal chamber form a continuous plug flow of concentrated polymer slurry solids which provides a pressure seal with an l d ratio of the plug of polymer slurry solids of 2 5 in an 8 u2032 4 u2033 long seal chamber having an l d ratio of 5 5 and with a cone angle of about 68 u00b0 on the seal chamber exit reducer the residence time of the continuous plug flow of concentrated polymer slurry solids is about 16 seconds the concentrated polymer slurry solids are continuously discharged from the bottom of the first flash tank at a temperature of about 180 u00b0 f and a pressure of about 240 psia through a seal chamber seal chamber exit reducer and a second transfer conduit into a feed inlet on a second flash tank the remaining liquid medium in the concentrated polymer slurry solids communicated to the second flash tank is flashed at a temperature of about 175 u00b0 f and at a pressure of about 25 psia to remove about 4 300 pounds per hour of isobutane and unreacted monomers which are condensed by compression and heat exchange a typical ethylene polymerization process would be conducted at a temperature of about 215 u00b0 f.