Integrated pyrolysis and hydrocracking systems and processes for efficiently cracking of hydrocarbon mixtures, such as mixtures including compounds having a normal boiling temperature of greater than 450° C., 500° C., or even greater than 550° C., such as whole crudes for example, are disclosed.

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.

Systems and methods are provided for conversion of polymers (such as plastic waste) to olefins. The systems and methods can include an initial pyrolysis stage where a plastic feedstock is delivered to the initial pyrolysis stage by one or more melt extruders. The one or more melt extruders can be heated to maintain the plastic feedstock in a liquid state during delivery of the plastic feedstock to the initial pyrolysis stage. This can allow for delivery of the plastic feedstock into the pyrolysis process with a controlled distribution of plastic into the pyrolysis reactor.

Systems and methods are provided for conversion of polymers (such as plastic waste) to olefins. The systems and methods can include an initial pyrolysis stage where a plastic feedstock is delivered to the initial pyrolysis stage by one or more melt extruders. The one or more melt extruders can be heated to maintain the plastic feedstock in a liquid state during delivery of the plastic feedstock to the initial pyrolysis stage. This can allow for delivery of the plastic feedstock into the pyrolysis process with a controlled distribution of plastic into the pyrolysis reactor.

Chemical recycling facilities for processing mixed plastic waste are provided herein. Such facilities have the capability of processing mixed plastic waste streams and utilize a variety of recycling facilities, such as, for example, solvolysis facility, a pyrolysis facility, a cracker facility, a partial oxidation gasification facility, an energy generation/energy production facility, and a solidification facility. Streams from one or more of these individual facilities may be used as feed to one or more of the other facilities, thereby maximizing recovery of valuable chemical components and minimizing unusable waste streams.

A process for producing light olefins comprising thermal cracking. Hydrocracked streams are thermally cracked to produce light olefins. A pyrolysis gas stream is separated into a light pyrolysis gas stream and a heavy pyrolysis gas stream. A light pyrolysis gas stream is separated into a normal paraffins stream and a non-normal paraffins stream. A normal paraffins stream is thermally cracked. The integrated process may be employed to obtain olefin products of high value from a crude stream.

A process for producing light olefins comprising thermal cracking. Hydrocracked streams are thermally cracked to produce light olefins. A pyrolysis gas stream is separated into a light pyrolysis gas stream and a heavy pyrolysis gas stream. A light pyrolysis gas stream is separated into a normal paraffins stream and a non-normal paraffins stream. A normal paraffins stream is thermally cracked. The integrated process may be employed to obtain olefin products of high value from a crude stream.

In chemical processes for cracking hydrocarbons, reactors are subject to coking During the decoke process carburization of the metal substrate can occur, negatively impacting reactor life. Decokes are also costly due to down-time where costs are incurred without production of commercial products. Reducing the frequency of decokes provides an opportunity to reduce the financial impacts of downtimes. A start-up procedure is described herein that limits initial coke deposition, leading to a reduced tendency for carburization of the metal substrate, improving reactor life, and more importantly, extending reactor run length.