GB1056651A - Oil refining - Google Patents

Abstract

<PICT:1056651/C4-C5/1> Lubricating oils containing water and other impurities, such as used crank-case oils, in feed line 30 are purified by distilling in a first column A1 to obtain a first overhead 52 and a first bottoms 91, condensing the overhead to obtain a dry reflux 55 and a first water fraction 65, fractionating the first bottoms in a second column 42 to obtain a second overhead 87, a second bottoms 103 and a plurality of lubricating oil side cuts, e.g. 94-97, condensing the second overhead to obtain an oil fraction 83 and a second water fraction 80, and steam stripping the water fractions, e.g. together in stripper 43 to remove dissolved impurities. The overhead condensers are preferably three-stage condensers (see Fig. 2, not shown) also giving intermediate condensates 60 and 82. An intermediate fraction may be removed from column 41 by line 54 and may be mixed with bottoms from column 42 to form a fuel oil. Both columns may be operated at about 100 mm. pressure and are fed with steam from lines 45 and 44. The impurity overheads from stripper 43 pass to condenser T3 and separator D1; being preferentially oil soluble the impurities are removed in the heads product in line 61.