A continuous process for converting waste plastic into recycle for polypropylene polymerization is provided. The process integrates refinery operations to provide an effective and efficient recycle process. The process comprises selecting waste plastics containing polyethylene and polypropylene and then 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 refinery FCC unit, from which is recovered a liquid petroleum gas C.sub.3 olefin/paraffin mixture. The C.sub.3 paraffins and C.sub.3 olefins are separated into different fractions with a propane/propylene splitter. The C.sub.3 olefin fraction is passed to a propylene polymerization reactor. The C.sub.3 paraffin fraction is optionally passed to a dehydrogenation unit to produce additional propylene and then the resulting C.sub.3 olefin is passed to a propylene polymerization reactor. The heavy fraction of pyrolyzed oil is passed to an isomerization dewaxing unit to produce a lubricating 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.

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.

Described herein are pyrolysis systems and pyrolysis processes for achieving a lighter yield slate than provided in conventional pyrolysis systems. Aspects include: recycling a gaseous pyrolysis product into the pyrolysis reactor to enhance the mixing of the pyrolysis system reactants; installing a bottoms liquid recycle stream to better mix the pyrolysis system reactants; and/or recycling at least a portion of a heavy fraction of the gaseous pyrolysis reactor effluent from a condenser system into the pyrolysis reactor liquid. These improvements can enhance the economic viability of plastic wastes to liquid and gaseous hydrocarbon products which are used for making circular chemical and polymer products.

Described herein are pyrolysis systems and pyrolysis processes for achieving a lighter yield slate than provided in conventional pyrolysis systems. Aspects include: recycling a gaseous pyrolysis product into the pyrolysis reactor to enhance the mixing of the pyrolysis system reactants; installing a bottoms liquid recycle stream to better mix the pyrolysis system reactants; and/or recycling at least a portion of a heavy fraction of the gaseous pyrolysis reactor effluent from a condenser system into the pyrolysis reactor liquid. These improvements can enhance the economic viability of plastic wastes to liquid and gaseous hydrocarbon products which are used for making circular chemical and polymer products.

A process increases the concentration of normal paraffins in a feed stream comprising separating a naphtha feed stream into a normal paraffin rich stream and a non-normal paraffin rich stream. A naphtha feed stream may be separated into a normal paraffin stream and a non-normal paraffin stream. An isomerization feed stream may be taken from the non-normal paraffin stream and isomerized over an isomerization catalyst to convert non-normal paraffins to normal paraffins and produce an isomerization effluent stream. The isomerization effluent stream may be separated into a propane stream and a C4+ hydrocarbon stream optionally in a single column. The C4+ hydrocarbon stream may be recycled to the step of separating a naphtha feed stream.

A process increases the concentration of normal paraffins in a feed stream comprising separating a naphtha feed stream into a normal paraffin rich stream and a non-normal paraffin rich stream. A naphtha feed stream may be separated into a normal paraffin stream and a non-normal paraffin stream. An isomerization feed stream may be taken from the non-normal paraffin stream and isomerized over an isomerization catalyst to convert non-normal paraffins to normal paraffins and produce an isomerization effluent stream. The isomerization effluent stream may be separated into a propane stream and a C4+ hydrocarbon stream optionally in a single column. The C4+ hydrocarbon stream may be recycled to the step of separating a naphtha feed stream.

To provide a method for producing olefins having the carbon atom number of 2 to 3 with a high yield. A method for producing olefins including following steps (1) and (2): step (1): heating a polyolefin plastic to obtain a decomposed product (pyrolysis step); and step (2): causing the decomposed product obtained at the step (1) to contact with an MFI zeolite containing sodium atoms in the range of 0.10% by mass to 0.30% by mass to obtain catalytically cracked products containing olefins (catalytic cracking step).

To provide a method for producing olefins having the carbon atom number of 2 to 3 with a high yield. A method for producing olefins including following steps (1) and (2): step (1): heating a polyolefin plastic to obtain a decomposed product (pyrolysis step); and step (2): causing the decomposed product obtained at the step (1) to contact with an MFI zeolite containing sodium atoms in the range of 0.10% by mass to 0.30% by mass to obtain catalytically cracked products containing olefins (catalytic cracking step).

A method for vaporizing liquid propane to be supplied as a raw material to a naphtha cracking ractor. The method comprises: decompressing liquid propane to lower a vaporization point and vaporize at least a portion of the liquid propane; utilizing vaporization heat, generated during vaporization of the portion of liquid propane, as a refrigerant; compressing the vaporized propane gas to increase pressure of the propane gas and produce compressed propane gas; and preheating the compressed propane gas. By using this method, it is possible to reduce pressure of liquid propane to a significantly lower pressure than the related art method so that all the vaporization latent heat or vaporization heat included in liquid propane may be utilized as a refrigerant, while also reducing heat energy consumed in a preheat process before it is supplied to the naphtha cracking reactor.