FIELD: oil and gas industry.
SUBSTANCE: invention relates to two versions of a device for fractionation of a gaseous fraction leaving the upper part of a fractional column of a catalytic cracking unit, wherein the fraction contains liquefied petroleum gas (LPG), light gasoline and a residual gas called "combustible gas", which itself contains a certain amount of ethylene. According to one of the versions, the device includes: a first absorption section, which enables to separate combustible gas and a stream of light gasoline and LPG, wherein said section is usually found in an existing catalytic cracking unit, a unit for catalytic conversion of ethylene to propylene and other products of interest, wherein the feedstock is a combustible gas, in which a large part of ethylene is converted mainly to propylene, as well as aromatic compounds and other products of interest in the presence of a zeolite-based catalyst, a new absorption section, into which streams from the conversion unit are introduced after re-compression, wherein propylene, butene and gasoline fractions contained in said streams are extracted in said absorption section using gasoline coming from an existing debutanizer, second section of auxiliary absorption, into which gas coming out of new absorption section is introduced, debutanization section, into which fractions of LPG and gasoline coming out of new absorption section are introduced, and which produces stabilized gasoline and light fraction of LPG.
EFFECT: use of the present invention enables to extract a maximum portion of the ethylene contained in the combustible gas in order to convert it mainly into propylene; other valuable products are formed, mainly butene and aromatic compounds.
9 cl, 5 dwg, 3 tbl, 2 ex
