Integrated catalytic cracking and steam pyrolysis process for olefins
View Patent ↗Integration of gas oil and light olefin catalytic cracking zones with a pyrolytic cracking zone to maximize efficient production of petrochemicals is disclosed. Integration of the units in parallel allows production of an overall product stream with maximum ethylene and/or propylene by routing various feedstreams and recycle streams to the appropriate cracking zone(s), e.g. ethane/propane to the steam pyrolysis zone and C 4 C 6 olefins to the light olefin cracking zone. This integration enhances the value of the material balances produced by the integrated units.
1. An olefin process, comprising:
passing a light alkane stream comprising ethane, propane or a combination thereof through a steam pyrolysis zone and quenching effluent therefrom to form a pyrolysis effluent enriched in ethylene, propylene or a combination thereof;
cracking a light hydrocarbon stream comprising olefins having at least 4 carbon atoms in a first FCC zone to form a first FCC effluent enriched in ethylene, propylene or a combination thereof;
cracking a refinery stream comprising gas oil, full range gas oil, resid, or a combination thereof, in a second FCC zone to form a second FCC effluent enriched in ethylene, propylene or a combination thereof;
fractionating the first and second FCC effluents together to remove heavy naphtha, light cycle oil, slurry oil, or a combination thereof and recover a combined olefin-containing FCC fraction;
conditioning the pyrolysis effluent together with the combined FCC fraction to remove oxygenates, acid gases, water or a combination thereof to form a conditoned stream;
separating the conditioned stream into at least a tail gas stream, an ethylene product stream, a propylene product stream, a light stream comprising ethane, propane, or a combination thereof, an intermediate stream comprising olefin selected from C 4 to C 6 olefins and mixtures thereof, and a heavy stream comprising C 6 and higher hydrocarbons;
recycling the light stream to the steam pyrolysis zone; and
recycling the intermediate stream to the first FCC zone.
2. The olefin process of claim 1 , further comprising recycling the heavy stream to the first FCC zone.
3. The olefin process of claim 1 , further comprising:
hydrotreating the heavy stream to obtain a hydrotreated stream;
extracting a product stream comprising benzene, toluene, xylenes or a mixture thereof from the hydrotreated stream to obtain a raffinate stream lean in aromatics; and
recycling the raffinate stream to the steam pyrolysis zone.
4. The olefin process of claim 1 , wherein the light alkane stream passed through the steam pyrolysis zone further comprises naphtha.
5. The olefin process of claim 1 , wherein the light alkane stream passed through the steam pyrolysis zone further comprises LPG.
6. The olefin process of claim 1 , wherein the light hydrocarbon stream cracked in the first FCC zone comprises FCC naphtha.
7. The olefin process of claim 1 , wherein the light hydrocarbon stream cracked in the first FCC zone comprises olefins having from 4 to 8 carbon atoms.
8. The olefin process of claim 1 , wherein the refinery stream cracked in the second FCC zone comprises waxy gas oil.
9. An olefin process unit, comprising:
parallel steam pyrolysis, light olefin FCC and gas oil-resid FCC zones for producing a combined effluent comprising ethylene and propylene, comprising:
means for passing a light alkane stream comprising ethane, propane or a combination thereof through the steam pyrolysis zone and quenching effluent therefrom to form a pyrolysis effluent enriched in ethylene, propylene or a combination thereof;
means for cracking a light hydrocarbon stream comprising olefins having at least 4 carbon atoms in the light olefin FCC zone to form a first FCC effluent enriched in ethylene, propylene or a combination thereof;
means for cracking a refinery stream comprising gas oil, full range gas oil, resid, or a combination thereof, in a gas-oil resid FCC zone to form a second FCC effluent enriched in ethylene, propylene or a combination thereof;
means for fractionating the first and second FCC effluents together to remove heavy naphtha, light cycle oil, slurry oil, or a combination thereof and recover a combined olefin-containing FCC fraction;
means for conditioning the combined effluent comprising the pyrolysis effluent and the combined olefin-containing FCC fraction to remove oxygenates, acid gases and water to form a conditioned stream;
means for separating the conditioned stream into at least a tail gas stream, an ethylene product stream, a propylene product stream, a light stream comprising ethane, propane, or a combination thereof, an intermediate stream comprising olefin selected from C 4 to C 6 olefins and mixtures thereof, and a heavy stream comprising C 6 and higher hydrocarbons;
means for recycling the light stream to the steam pyrolysis zone; and
means for recycling the intermediate stream to the first FCC zone.