Process for recovery of propylene and LPG from FCC fuel gas using stripped main column overhead distillate as absorber oil

A process for recovery of propylene and C4s from a product mixture obtained by contacting a hydrocarbon feed with a catalyst in a fluid catalytic cracking process, wherein said recovery is achieved by following sequence of steps:

• (i) distilling the above said product mixture in main fractionator to obtain heavier liquid products as side/bottom draws and a gaseous top product consisting of components boiling below 215° C.,
• (ii) cooling and condensing the gaseous top product to obtain gas-liquid mixture and thereafter separating said obtained gas- liquid mixture in a receiver cum separator to obtain a liquid fraction referred to as unstabilized naphtha and a lighter gaseous fraction,
• (iii) sequentially compressing, cooling and separating in a two stage Wet Gas compressor train said lighter gaseous fraction obtained from step (ii) to finally obtain gaseous and liquid fractions from a high pressure separator,
• (iv) feeding the liquid fraction obtained in step (iii) to a de-ethanizer wherein ethane and lighter components stripped off from the lighter gaseous fractions are recycled back to high pressure receiver in step (iii) whereas the de-ethanized liquid product is fed to debutanizer column,
• (v) separating butane and lighter components present in the de-ethanized liquid product as overhead gaseous fraction in the debutanizer column and obtaining heavier fraction as bottom product referred to as debutanizer bottoms,
• (vi) feeding unstabilized naphtha obtained in step (ii) to a naphtha stripper wherein lighters stripped off from unstabilized naphtha feed are recycled to step (ii) and heavier liquid fraction, after cooling to about 30° C. to 40° C., is used as lean oil in the absorber in step (vii),
• (vii) contacting gaseous fraction obtained from high pressure separator in step (iii) in an absorber with the liquid fraction as obtained in step (vi) and a part of the debutanizer bottoms as obtained in step (v),
• (viii) feeding the rich oil from the absorber bottom liquid to de-ethanizer via high pressure receiver,
• characterized by further stripping of the unstabilized naphtha as obtained in step (ii), said stripping achieved by feeding the unstabilized naphtha as obtained in step (ii) to an intermediate stripper column, wherein lighter components present in the feed are stripped off to obtain a heavier liquid fraction having an initial boiling point of between from about 25° C. to about 50° C. and said heavier fraction, after cooling to about 20° C. to 30° C., is used as lean oil in the absorber in step (vii) and the lighters stripped off from unstabilized naphtha are recycled back to main fractionator overhead condensers in step (ii).