GB851437A - Process of steam-cracked naphtha light end products - Google Patents

Abstract

<PICT:0851437/IV(b)/1> In recovering C2-C5 hydrocarbons from the gaseous product of steam cracking naphtha containing some higher boiling constituents and from which higher boiling hydrocarbons have been separated in a quenching zone, the gas is cooled to condense C4+ hydrocarbons and water, separated in a separating zone into uncondensed gas, condensed hydrocarbon and water, the uncondensed gas from the separating zone is passed to a vapour compression zone, and thus further condensed hydrocarbons are passed to a fractionation zone the C5- overhead from which is passed with the gas from the quenching to be condensed and separated. The effleuent from the cracking coil 3 is mixed with quench oil and passed to quench tower 7 where it is contacted in countercurrent with more quench oil. Part of the circulating quench oil is bled off by line 15, fresh being added by line 9, while some oil is taken off by line 17 for use as a sponge oil in removing heavier hydrocarbons from a C2 cut and the fat oil is returned by line 18. The overhead from tower 7 is cooled in cooler 21 and separated in separator 22, water being removed, some condensed hydrocarbon being returned by line 19 to the quench tower the remainder being fed to the top of fractionator 26 to separate C6+ as bottoms and C5- overhead, the latter being passed to cooler 21 and separator 22. Gases from the separator are compressed and cooled and liquid formed separated in knock-out drum 34 and passed to fractionator 26. Gases are further compressed and cooled and the gases and liquids obtained separately caustic treated at 48 and passed together to absorber 50 where they are contacted with an oil boiling in the range 80 DEG -200 DEG F. to absorb C3 and higher boiling hydrocarbons which are then recovered in debutaniser 58 while the C2 fraction is passed to absorber 54 where it is contacted with a sponge oil from the circulating quench oil from tower 7.