to isolate the desired fractions while effecting a reduction in the production of fouling polymers application_number US 95062292 A description the present invention of a method for the reduction of fouling in the treatment of cracked hydrocarbon gases involves the use of a dual pressure dual column fractionator configuration rather than the conventional single pressure single column fractionator configurations while the dual pressure dual column fractionator configuration of the present invention is suitable for a variety of fractionating column systems fig1 and the subsequent discussion describes without in any way limiting the scope of the present invention one particular embodiment of the present invention namely a dual pressure dual column debutanizer the feedstock 10 may a mixture of cracked hydrocarbons generally feedstock 10 will be the bottoms stream c 4 and c 5 fraction from a deethanizer or a depropanizer although alternative feed compositions and sequences are possible feedstock 10 is fed into a preheater 11 wherein the feedstock is partially or totally vaporized preheater 11 which serves to vaporize all or part of the feedstock is operated at temperatures ranging from about 10 to about 200 preferably from about 50 u00b0 to about 90 u00b0 c the preheated feedstock.