FIELD: petrochemical processes.
SUBSTANCE: invention relates to olefin-containing hydrocarbon stock steam cracking process ensuring elevated content of light olefins in stream leaving steam cracking process, which process comprises passing first hydrocarbon feedstock containing one or more olefins through catalytic cracking reactor containing crystalline silicate to form intermediate stream containing olefins having lower molecular mass than in starting feedstock; fractionation of intermediate stream of form fraction with lower carbon atom number and fraction with higher carbon atom number followed by passing fraction with higher carbon atom number, as second hydrocarbon feedstock, through steam cracking installation to produce stream leaving steam cracking installation. Invention further relates to steam cracking process of olefin-containing hydrocarbon stock, which comprises passing first hydrocarbon feedstock containing one or more olefins and further containing one or more of the following: crude hydrotreated stock C4, light catalytic cracking gasoline, refined stock 2, refined stock 1, refined stock 2 from methyl tert-butyl ether or ethyl tert-butyl ether synthesis installation, olefin metathesis installation raffinate, hydrotreated olefin-containing stream from fluid-catalytic cracking plant or light cracking plant, or delayed cocking plant, through reactor containing crystalline silicate to form intermediate stream containing olefins having lower molecular mass than in starting feedstock and passing this intermediate stream, as second starting hydrocarbon feedstock, through steam cracking installation to produce stream leaving steam cracking installation. Invention also discloses olefins-containing hydrocarbon stock steam cracking process comprising steam cracking of the first hydrocarbon feedstock including paraffin-containing hydrocarbon stock, steam cracking of the second hydrocarbon feedstock containing hydrocarbons C4 and hydrocarbons with higher molecular mass, the second hydrocarbon feedstock containing one or more olefins and including lower fraction of intermediate stream obtained by catalytic cracking of a third hydrocarbon feedstock in reactor containing crystalline silicate to form intermediate stream containing olefins with lower molecular mass than that in the third feedstock, after which two streams leaving steam cracking process are combined to produce combined stream.
EFFECT: increased conversion of olefins into high-purity lighter olefins, in particular into propylene, enabled catalytic cracking of olefin-containing streams with high olefin level into propylene no matter which origin and composition of olefin feedstock is, and increased economical efficiency of process.
29 cl, 5 dwg, 12 tbl, 64 ex
