GB381429A - Process and apparatus for the simultaneous recovery and purification of benzol contained in benzolated oils - Google Patents

Abstract

Benzol is recovered in a continuous operation from oil used for washing gases by heating the oil with subsequent expansion in two stages, the second stage being under vacuum, rectifying the vapours to remove light impurities, e.g. carbon disulphide and impurities heavier than benzol, washing with acid and alkali the separated benzol, and finally distilling it under vacuum by heat exchange with the impure vapours to remove resins. The benzolated oil from a reservoir A is pumped through recuperators C, C<1>, and then through a coil D heated by steam. The oil issues with reduction of pressure at a valve 6 into a rectifying column E, E<1>. The lighter fractions are condensed in condensers F, G, the impurities of low boiling-point remaining uncondensed and being separated in a separator g and removed through a test gauge W while the condensate is returned as reflux through a pipe 55. The toluolxylol fraction is drawn off through a pipe 16, condenser T and test gauge U. The benzol fraction whose rectification is controlled by a heat exchanger V, V<1> is drawn off through a line 11 and is treated in the lower part Z of a column filled with porcelain balls with sulphuric <PICT:0381429/III/1> acid from a tank R and in the upper portion Z<1> with carbonate of soda lye from a tank R<1>. The benzol is distilled to remove resins in the condenser F and the vapours are condensed in a condenser Q in which vacuum is produced to reduce the boiling-point of the benzol by connecting the condensate outlet 14 with an injector S operated by steam which is afterwards used in the heat exchanger V. The heavy residues and debenzolated oil are passed through a pipe 25 to a column K, L operated under vacuum produced by connecting the condensate outlet M of the condenser M to an ejector N operated by steam which is also passed to the lower part V<1> of the heat exchanger V, V<1>. Condensate from the condenser M is returned to the column as reflux and the final reflux is removed to a chamber L<1> where the last traces of solvent are removed by steam. The residue consists mainly of naphthalene and is removed through a barometric pipe 31 to crystallizers 33. The purified oil from the bottom of the column K is passed through a pipe 28, recuperators C, C<1>, and a water cooler to a reservoir I.