IMPROVED DEWAXING AND WAXING FILTERABILITY BY REDUCING SCRAPER SPEED IN COOLING DEVICE EQUIPPED WITH SCRAPER

摘要

A hydrocarbon oil dewaxing process comprises passing the waxy oil through a staged vertical tower, injecting cold solvent at a plurality of stages along the vertical tower under conditions of high agitation to achieve substantially instantaneous mixing at each point, continuing the chilling, preferably at a rate of from 0.55 to 4.44°C (1 to 8°F) per minute, by means of cold solvent injection until a temperature above the filtering temperature but less than 22.2°C (40°F) above the filtering temperature is reached. The oil is subsequently cooled to the wax separation temperature in rotating-element scraped-surface chillers. The operating speed of the rotating elements in the scraped surface chiller is in the range of from 8 to 14% of the original design operation speed. Operation at this reduced speed improves wax separation rates by about 10 to 20%while not substantially adversely affecting the heat transfer performance of the chillers.