Provided is a continuous process for converting waste plastic into recycle for polyethylene polymerization. In one embodiment, the process comprises selecting waste plastics containing polyethylene and/or polypropylene and passing the waste plastics through a pyrolysis reactor to thermally crack at least a portion of the polyolefin waste and produce a pyrolyzed effluent. The pyrolyzed effluent is separated into offgas, a naphtha/diesel fraction, a heavy fraction, and char. The naphtha/diesel fraction is passed to a crude unit distillation column in a refinery where a straight run naphtha (C.sub.5-C.sub.8) fraction or a propane/butane (C.sub.3-C.sub.4) fraction is recovered. The straight run naphtha fraction (C.sub.5-C.sub.8) or the propane/butane (C.sub.3-C.sub.4) fraction is passed to a steam cracker for ethylene production. The heavy fraction from the pyrolysis unit can also be passed to an isomerization dewaxing unit to produce a base oil.

Provided is a continuous process for converting waste plastic into recycle for polyethylene polymerization. In one embodiment, the process comprises selecting waste plastics containing polyethylene and/or polypropylene and passing the waste plastics through a pyrolysis reactor to thermally crack at least a portion of the polyolefin waste and produce a pyrolyzed effluent. The pyrolyzed effluent is separated into offgas, a naphtha/diesel fraction, a heavy fraction, and char. The naphtha/diesel fraction is passed to a crude unit distillation column in a refinery where a straight run naphtha (C.sub.5-C.sub.8) fraction or a propane/butane (C.sub.3-C.sub.4) fraction is recovered. The straight run naphtha fraction (C.sub.5-C.sub.8) or the propane/butane (C.sub.3-C.sub.4) fraction is passed to a steam cracker for ethylene production. The heavy fraction from the pyrolysis unit can also be passed to an isomerization dewaxing unit to produce a base oil.

Methods for producing olefins through hydrocarbon steam cracking include passing a hydrocarbon feed that includes one or more hydrocarbons to a hydrocarbon cracking unit and passing one or more sulfur-containing compounds to the hydrocarbon cracking unit. The sulfur- containing compounds include at least hydrogen sulfide gas, and a flow rate of the sulfur- containing compounds to the hydrocarbon cracking unit is sufficient to produce a molar concentration of elemental sulfur in the hydrocarbon cracking unit of from 10 ppm to 200 ppm. The methods include cracking the hydrocarbon feed in the hydrocarbon cracking unit to produce a cracker effluent and contacting the cracker effluent with a quench fluid in a quench unit to produce at least a cracked gas and a first pygas. The first pygas has a concentration of carbon disulfide less than 50 ppmw based on the total mass flow rate of the first pygas.

Methods for producing olefins through hydrocarbon steam cracking include passing a hydrocarbon feed that includes one or more hydrocarbons to a hydrocarbon cracking unit and passing one or more sulfur-containing compounds to the hydrocarbon cracking unit. The sulfur- containing compounds include at least hydrogen sulfide gas, and a flow rate of the sulfur- containing compounds to the hydrocarbon cracking unit is sufficient to produce a molar concentration of elemental sulfur in the hydrocarbon cracking unit of from 10 ppm to 200 ppm. The methods include cracking the hydrocarbon feed in the hydrocarbon cracking unit to produce a cracker effluent and contacting the cracker effluent with a quench fluid in a quench unit to produce at least a cracked gas and a first pygas. The first pygas has a concentration of carbon disulfide less than 50 ppmw based on the total mass flow rate of the first pygas.

The present invention relates to an NCC process and an apparatus for producing light olefins and aromatics, wherein the fraction comprising ethane and/or propane (12) from the cracking effluent is sent at least partly into a steam cracking furnace (19), fed with steam (20), to produce a steam cracking effluent (21) comprising ethylene and/or propylene.

The present invention relates to an NCC process and an apparatus for producing light olefins and aromatics, wherein the fraction comprising ethane and/or propane (12) from the cracking effluent is sent at least partly into a steam cracking furnace (19), fed with steam (20), to produce a steam cracking effluent (21) comprising ethylene and/or propylene.

A method for cracking crude oil includes delivering the crude oil to a first tube group of a convection section of a cracking furnace for preheating and then performing vaporization to obtain a first gas phase and a first liquid phase; performing high-pressure extraction on the first liquid phase to obtain a non-asphalt oil and an asphalt; and mixing the first gas phase and the non-asphalt oil with water vapor respectively, or mixing the first gas phase with the non-asphalt oil prior to mixing with water vapor, then delivering the same to a second tube group of the convection section of the cracking furnace for heating, followed by delivering same to a radiation section of the cracking furnace for cracking to obtain a cracked product, and separating the cracked product to obtain low-carbon olefins.

A method for cracking crude oil includes delivering the crude oil to a first tube group of a convection section of a cracking furnace for preheating and then performing vaporization to obtain a first gas phase and a first liquid phase; performing high-pressure extraction on the first liquid phase to obtain a non-asphalt oil and an asphalt; and mixing the first gas phase and the non-asphalt oil with water vapor respectively, or mixing the first gas phase with the non-asphalt oil prior to mixing with water vapor, then delivering the same to a second tube group of the convection section of the cracking furnace for heating, followed by delivering same to a radiation section of the cracking furnace for cracking to obtain a cracked product, and separating the cracked product to obtain low-carbon olefins.

Provided in one embodiment is a continuous process for converting waste plastic into recycle for polyethylene polymerization. The process comprises selecting waste plastics containing polyethylene and/or polypropylene, and passing the waste plastics through a pyrolysis reactor to thermally crack at least a portion of the polyolefin waste and produce a pyrolyzed effluent. The pyrolyzed effluent is separated into offgas, a pyrolysis oil and optionally wax comprising a naphtha/diesel and heavy fraction, and char. The pyrolysis oil and wax is passed to a refinery FCC unit from which a liquid petroleum gas C.sub.3-C.sub.5 olefin/paraffin mixture fraction is recovered. The liquid petroleum gas C.sub.3-C.sub.5 olefin/paraffin mixture fraction is passed to a refinery alkylation unit, with a propane and butane fraction recovered from the alkylation unit. The propane and butane fraction is then passed to a steam cracker for ethylene production. In another embodiment, a naphtha fraction (C.sub.5-C.sub.8) is recovered from the alkylation unit and passed to the steam cracker. In another embodiment, a propane/propylene fraction (C.sub.3-C.sub.3.sup.=) is recovered from the FCC and passed to the steam cracker.

Provided in one embodiment is a continuous process for converting waste plastic into recycle for polyethylene polymerization. The process comprises selecting waste plastics containing polyethylene and/or polypropylene, and passing the waste plastics through a pyrolysis reactor to thermally crack at least a portion of the polyolefin waste and produce a pyrolyzed effluent. The pyrolyzed effluent is separated into offgas, a pyrolysis oil and optionally wax comprising a naphtha/diesel and heavy fraction, and char. The pyrolysis oil and wax is passed to a refinery FCC unit from which a liquid petroleum gas C.sub.3-C.sub.5 olefin/paraffin mixture fraction is recovered. The liquid petroleum gas C.sub.3-C.sub.5 olefin/paraffin mixture fraction is passed to a refinery alkylation unit, with a propane and butane fraction recovered from the alkylation unit. The propane and butane fraction is then passed to a steam cracker for ethylene production. In another embodiment, a naphtha fraction (C.sub.5-C.sub.8) is recovered from the alkylation unit and passed to the steam cracker. In another embodiment, a propane/propylene fraction (C.sub.3-C.sub.3.sup.=) is recovered from the FCC and passed to the steam cracker.