Agitated heat exchanger to chill solvent-oil and wax slurry to wax filtration temperature

摘要

An improved process for dewaxing waxy hydrocarbon oils, wherein said waxy oil is introduced at a temperature above its cloud point into a direct chilling zone divided into a plurality of stages, passing said waxy oil from stage-to-stage of said chilling zone, introducing a cold dewaxing solvent into at least a portion of said stages, maintaining a high degree of agitation in at least a portion of the stages containing solvent and waxy oil, thereby effecting substantially instantaneous mixing thereof while cooling said solvent- waxy oil mixture, preferably at a rate of from about 1° to 8° F. /min., as it progresses through said direct chilling zone to a temperature greater than the wax separation temperature, whereby a substantial portion of the wax is precipitated from said waxy oil under conditions of said high degree of agitation and forming a solvent-oil mixture containing precipitated wax (slurry I), withdrawing said slurry I from said direct chilling zone and cooling same to the wax separation temperature in an indirect chilling zone thereby precipitating a further portion of wax from said waxy oil and separating said precipitated wax from the wax-oil-solvent mixture in solid-liquid separation means, the improvement comprising using as the indirect chilling zone an indirect heat exchanger means operated at a high level of agitation. Expressed in terms of Impeller Reynolds Number the agitation is on the order of about 1,000 to 1,000,000.P PAlternatively, the staged, agitated, direct chilling zone is totally replaced by the high agitation indirect heat exchanger means.