Methods and systems for conversion of mixed plastics to pyrolysis oil with filtration integrated upstream of reactors

Abstract

Provided here are methods and systems for converting mixed plastic waste into pyrolysis oil with a filtration unit integrated upstream of one or more reactors. A method provided herein includes depolymerizing a polyolefin feed stream to produce a molten oligomer stream and a chlorine-rich gas stream and dechlorinating the molten oligomer stream to produce a dechlorinated molten oligomer stream and a chlorine-rich fluid stream. The method includes filtering the dechlorinated molten oligomer stream through a heated melt filter to produce a filtered molten oligomer stream and a solid residue. The method includes thermally cracking the filtered molten oligomer stream to produce a cracked product stream, distilling at least a portion of the cracked product stream to produce a pyrolysis oil product stream having a final boiling point of about 350 degrees Celsius (°C) or less and a heavy distillate stream, and supplying the pyrolysis oil product stream for steam cracking.

Description

24CHEM0021 - WO-ORD1METHODS AND SYSTEMS FOR CONVERSION OF MIXED PLASTICS TO PYROLYSIS OIL WITH FILTRATION INTEGRATED UPSTREAM OF REACTORSTECHNICAL FIELD

[0001] The present disclosure generally relates to methods and systems for decontaminating and converting mixed plastic waste (MPW) to produce pyrolysis oil. More specifically, the present disclosure relates to methods and systems including a filtration unit integrated upstream of one or more reactors.BACKGROUND

[0002] Mixed plastic waste can be recycled to produce certain higher-value products, such as a hydrocarbon-rich pyrolysis oil, or pyoil, suitable for use as a feed stream to one of a steam cracker, refinery, or other process units thereof. The commercial production of certain pyrolysis oils from waste plastic is insufficient for removing suitable amounts of chlorides, aromatics, and / or heteroatoms from the resulting product. These contaminated pyrolysis oils also may have high boiling points, which would thus limit the amount or blend ratio of pyrolysis oil that can be coprocessed in a steam cracker. In particular, the high-boiling pyrolysis oil can cause incomplete evaporation in a convection section of the steam cracker, which causes fouling issues that potentially reduce operating or cycle time for the steam cracker between servicing. As a consequence, the issue of incomplete evaporation limits the amount of plastic-derived pyrolysis oil that can be processed for valorization. In addition, the presence of contaminants like chlorides and other heteroatoms would limit the use of this product as a feedstock.

[0003] Additional issues are experienced with respect to the preparation and logistics associated with pyrolysis oil. For example, the quality of waste plastic is continuously variable, which causes a correspondingly variable quality in the pyrolysis oil produced from the waste plastic. The inconsistency of pyrolysis oil produced from the variable mixed plastic waste requires adding expensive control measures and equipment at the manufacturing sites to manufacture a feed having a suitably consistent quality for use in steam crackers and / or refineries.

[0004] Moreover, certain commercial production facilities for pyrolysis oil suffer from high production of waste products, such as gases and coke. For example, a production of about 15 to 20 weight percent (wt. %) of gases and about 10 wt. % of coke is typical of such facilities. This quantity of feedstock is removed or lost from the production system and thus causes undesirably24CHEM0021 - WO-ORD2 high carbon inefficiency. Commercially produced pyrolysis oils also tend to have low stability during storage, which causes in gumming issues that lead to further losses in storage tanks and transport containers.SUMMARY

[0005] Based on at least the above issues, Applicant has identified a demand for a methods and systems that can efficiently produce pyrolysis oil with low levels of heavy components and contaminants, which increases the blendability and compatibility of pyrolysis oil with steam cracker feeds. Applicant has also identified a demand for more carbon efficient methods and systems that reduce or minimize losses due to coke and / or gases and thus increasing or maximizing liquid product yield.

[0006] The present disclosure includes methods and systems for decontaminating and converting mixed plastic waste into pyrolysis oil with improved quality and increased yield than was previously available, without unduly increased operating and equipment costs. More specifically, the present disclosure relates to methods and systems for producing pyrolysis oil having a relatively low final boiling point, such as about 350 degrees Celsius (°C) or less, from mixed plastic waste that is provided in an integrated system which includes a devolatilization extruder, a dechlorination unit, a filtration unit having a heated melt filter. Downstream of the filtration unit, the integrated system includes one or two reactors or thermal crackers combined with a distillation column.

[0007] The disclosure herein provides several examples and embodiments of methods and systems for the efficient production of high-quality pyrolysis oil. Examples include a method that includes depolymerizing a polyolefin feed stream rich in poly ethene (PE) and poly(l- methylethylene) (PP) to produce a molten oligomer stream and a chlorine-rich gas stream and dechlorinating the molten oligomer stream to produce a dechlorinated molten oligomer stream and a chlorine-rich fluid stream. The method includes filtering the dechlorinated molten oligomer stream through a heated melt filter having a pore size ranging between about 3 micrometers (pm) and 100 pm to produce a filtered molten oligomer stream and a solid residue containing heteroatoms. The method includes thermally cracking the filtered molten oligomer stream to produce a cracked product stream, distilling at least a portion of the cracked product stream to produce a pyrolysis oil product stream having a final boiling point of about 350 degrees Celsius24CHEM0021 - WO-ORD3(°C) or less and a heavy distillate stream, and supplying the pyrolysis oil product stream for steam cracking.

[0008] In some examples, the method includes separating the cracked product stream into a first light cracked stream and a heavy cracked stream, and the at least a portion of the cracked product stream provided for distillation includes the first light cracked stream. The method includes thermally cracking the heavy cracked stream and the heavy distillate stream to produce a second light cracked stream and an additional solid residue containing heteroatoms. The method includes distilling the second light cracked stream along with the first light cracked stream to produce the pyrolysis oil product stream and the heavy distillate stream and recycling the heavy distillate stream for thermal cracking with the heavy cracked stream.

[0009] In some examples, the at least a portion of the cracked product stream provided for distillation includes an entirety of the cracked product stream, and the method further includes supplying the heavy distillate stream for refining at a refinery. In some examples, the method further includes removing the solid residue from the heated melt filter continuously. In some examples, the method further includes removing the solid residue from the heated melt filter intermittently. In some examples, the heated melt filter includes a multi-stage filter. In some examples, the depolymerizing includes operating a devolatilization extruder at a temperature ranging from about 200 °C to 450 °C with a residence time of about 10 minutes or less.

[0010] In some examples, the dechlorinating includes operating a dechlorination unit with a residence time of about 2 hours or less, and the dechlorinated molten oligomer stream includes oligomers with a molecular weight ranging from about 1682 grams per mole (g / mol) to 50000 g / mol. In some examples, the method further includes producing the polyolefin feed stream before depolymerizing the polyolefin feed stream by separating a mixed waste plastic stream into the polyolefin feed stream and one or more plastic streams rich in poly(l -phenylethylene) (PS), poly(l -chloroethylene) (PVC), polyethylene terephthalate) (PET), or a combination thereof.

[0011] Examples include a system that includes a devolatilization extruder configured to receive a polyolefin feed stream rich in PE and PP and produce a molten oligomer stream and a chlorine- rich gas stream and a dechlorination unit configured to receive the molten oligomer stream and produce a dechlorinated molten oligomer stream and chlorine-rich gas and / or liquid streams. The system includes a filtration unit including a heated melt filter and configured to receive the dechlorinated molten oligomer stream and produce a filtered molten oligomer stream and a first24CHEM0021 - WO-ORD4 solid residue containing heteroatoms. The system includes a first thermal cracking unit configured to receive the filtered molten oligomer stream and produce a first light cracked stream and a heavy cracked stream and a second thermal cracking unit configured to receive the heavy cracked stream and a heavy distillate stream and produce a second light cracked stream and a second solid residue containing heteroatoms. The system includes a distillation unit configured to receive the first light cracked stream and the second light cracked stream, produce the heavy distillate stream routed to the second thermal cracking unit and a pyrolysis oil product stream having a final boiling point of about 350 °C or less, and route the pyrolysis oil product stream to a steam cracker.

[0012] In some examples, the heated melt filter includes a pore size ranging between about 3 pm and 100 pm. In some examples, the heated melt filter includes a multi-stage filter. In some examples, the first solid residue is continuously removed from the filtration unit and the second solid residue is removed continuously from the second thermal cracking unit. Optionally, the first solid residue and the second solid residue of certain examples is collected in the solid vessel and heated / pyrolyzed to produce solid residue low on organics and a predominantly gaseous product from solids vessel, with the predominantly gaseous product being routed to a scrubber.

[0013] In some examples, the system further includes a feed preparation zone positioned upstream of the devolatilization extruder to prepare the polyolefin feed stream. The feed preparation zone includes a debaler, a shredder, a granulator, a washer, a density -based separator, a centrifuge, a dryer, a magnetic separator, a non-magnetic separator, or a combination thereof. In some examples, the devolatilization extruder includes one or more single or twin screw extruders, augers, heated screw feeders, kneader reactors, multi-stage heated pumps, or a combination thereof and the dechlorination unit includes a condensation and scrubbing system.

[0014] Aspects and advantages of these exemplary embodiments and other embodiments, are discussed in detail herein. Moreover, it is to be understood that both the foregoing information and the following detailed description provide merely illustrative examples of various aspects and embodiments, and are intended to provide an overview or framework for understanding the nature and character of the claimed aspects and embodiments. Accordingly, these and other objects, along with advantages and features of the present disclosure, will become apparent through reference to the following description and the accompanying drawings. Furthermore, it is to be understood that the features of the various embodiments described herein are not mutually exclusive and may exist in various combinations and permutations.24CHEM0021 - WO-ORD5BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present disclosure, are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure, and together with the detailed description, serve to explain principles of the embodiments discussed herein. No attempt is made to show structural details of this disclosure in more detail than may be necessary for a fundamental understanding of the embodiments discussed herein and the various ways in which they may be practiced. According to common practice, the various features of the drawings discussed below are not necessarily drawn to scale. Dimensions of various features and elements in the drawings may be expanded or reduced to more clearly illustrate embodiments of the disclosure.

[0016] FIG. 1 is a diagrammatic representation of a system for producing various products including high value pyrolysis oil from mixed plastic waste, according to an example.

[0017] FIG. 2 is a diagrammatic representation of a system for receiving a polyolefin feed stream and producing pyrolysis oil with a desirably low boiling point based on the integration of a filtration unit upstream of two thermal cracking units, according to an example.

[0018] FIG. 3 is a diagrammatic representation of a system for receiving a polyolefin feed stream and producing pyrolysis oil based on the integration of a filtration unit upstream of one thermal cracking unit, according to an example.

[0019] FIG. 4 is a diagrammatic representation of a control system for controlling operation of the disclosed systems for producing pyrolysis oil, according to an example.DETAILED DESCRIPTION

[0020] The present disclosure describes various embodiments related to methods and systems for decontamination and conversion of mixed plastics to pyrolysis oil having a suitably low final boiling point for incorporation into a steam cracker feed. Additionally, the present disclosure describes various embodiments related to methods and systems for decontamination and conversion of mixed plastics to pyrolysis oil for incorporation into a steam cracker feed as well as a refinery feed. Additional embodiments and details thereof are described and disclosed below. In the following description, numerous details are set forth in order to provide a thorough understanding of the various embodiments. In other instances, well-known processes, devices, and systems may not have been described in particular detail in order not to unnecessarily obscure the24CHEM0021 - WO-ORD6 various embodiments. Additionally, illustrations of the various embodiments may omit certain features or details in order to not obscure the various embodiments.

[0021] The description may use the phrases “in certain embodiments,” “in various embodiments,” “in an embodiment,” or “in embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments of the present disclosure, are synonymous. The terms “about” or “approximately” are defined as being close to as understood by one of ordinary skill in the art. In one non-limiting embodiment, the terms are defined to be within 10%, within 5%, within 1%, or within 0.5%.

[0022] The terms “removing,” “removed,” “reducing,” “reduced,” or any variation thereof, when used in the claims and / or the specification includes any measurable decrease of one or more components in a mixture to achieve a desired result. The use of the words “a” or “an” when used in conjunction with any of the terms “comprising,” “including,” “containing,” or “having,” in the claims or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” The term “plurality” as used herein refers to two or more items or components. The term “ppm” with reference to a component refers to that component having a concentration specified in part per million. The terms “wt. %”, “vol. %”, or “mol. %” refers to a weight, volume, or molar percentage of a component, respectively, based on the total weight, the total volume of material, or total moles, that includes the component. In a nonlimiting example, 10 grams of component in 100 grams of the material is 10 wt. % of component.

[0023] As used herein, the term “mixed plastic waste” refers to plastic components, parts, pellets, or other generally solid pieces formed of various polymers, which can include any combination of additives or fillers designed to facilitate the original use of the plastic. For example, certain polymers included mixed plastic waste include poly(l -phenylethylene) or polystyrene (PS), poly(l -chloroethylene) or polyvinyl chloride (PVC), polyethylene terephthalate) (PET), poly ethene (PE), and polypropylene or poly(l -methylethylene) (PP).

[0024] As introduced above, certain pyrolysis oils that are commercially produced from mixed waste plastic include an undesirably high content of contaminants, such as chlorides, aromatics, and heteroatoms, including metal and non-metal heteroatoms and also have heavy components with undesirably high boiling points, such as boiling points above about 350, 375, or 400 degrees Celsius (°C), in certain examples. For example, the operating temperature of liquid steam crackers24CHEM0021 - WO-ORD7 may not operate at temperatures sufficient to boil the heavy components of the pyrolysis oil completely. As such, the amount of the pyrolysis oil that can be blended for co-processing in a steam cracker is greatly limited by the incomplete evaporation and corresponding fouling in convection sections of steam crackers.

[0025] As will be understood, the present disclosure provides for an intensified thermal cracking process and configuration integrated with specialized heated melt filtration that enables preparation of substantially or partially decontaminated pyrolysis oil with low levels of heteroatoms, including chlorides, metals, and non-metals. The flexible methods and systems described herein further maintain a consistent pyrolysis oil quality, independent or irrespective of any feedstock quality variation. For example, the present disclosure can resolve issues regarding the continuously variable quality of mixed plastic waste by efficiently separating and conditioning the mixed plastic waste to produce high-quality polyolefin feed streams suitable for chemical recycling.

[0026] The present disclosure further improves the blendability of pyrolysis oil for steam cracker use, thereby increasing the overall efficiency for chemically recycling mixed plastic waste. As such, the pyrolysis oil products produced herein can be fed completely or in high blend ratios with other feeds to a steam cracker that delivers higher selectivity for olefins such as ethene and propene. In some examples, flexibility provided by the high-quality pyrolysis oil enables the pyrolysis oil to be fed to a refinery, a steam cracker, or both with any desired flow ratio parameters. Moreover, the produced pyrolysis oil has high storage stability and thus addresses the problem of surface gumming otherwise experienced by contaminated pyrolysis oil during transportation or long-term storage. The methods and systems disclosed herein also leverage process intensification to reduce an equipment size and corresponding capital expenditure involved in unit operations compared to previously available pyrolysis oil production.

[0027] Methods and systems described herein are utilized for producing pyrolysis oil having a relatively low final boiling point from mixed plastic waste, which includes a heated melt filter integrated downstream of a devolatilization extruder and dechlorination unit and upstream of one or two thermal crackers. For example, certain systems include (i) a devolatilization extruder that produces a partially dechlorinated molten oligomer stream from a feedstock rich in polyethylene (PE) and polypropylene (PP), (ii) a dechlorination unit that further removes chlorides from the molten oligomer stream, (iii) a filtration unit that removes solids from the dechlorinated molten24CHEM0021 - WO-ORD8 oligomer stream, (iv) a single or two stage thermal cracking unit that produces a cracked product stream from the filtered molten oligomer stream, and (v) a distillation unit that receives at least a portion of the cracked product stream to produce a pyrolysis oil product stream and a heavy pyoil stream. In certain examples, the system includes (vi) an additional thermal cracking unit that receives the heavy pyoil stream from the distillation unit and produces a heavy portion of the cracked product stream and a light cracked stream directed to distillation unit for further separation. In certain embodiments the heavy portion of the cracked product stream is a solid residue. In certain examples, the filter is a heated melt filter having a pore size ranging between about 3 and 100 micrometers (pm).

[0028] FIG. 1 is a diagrammatic representation of a system 100 or waste plastic conversion facility for receiving mixed plastic waste and producing various products, including high value pyrolysis oil. The system 100 of the illustrated example includes a feed preparation unit, a first mechanical recycling unit, a second mechanical recycling unit, a chemical recycling unit, a steam cracker, and a refinery. In additional detail, the system 100 facilitates conversion of a mixed plastic waste feed 102 or stream to produce improved, low-boiling pyrolysis oil products. In some examples, the mixed plastic waste feed 102 contains various plastic components having varied compositions. The mixed plastic waste feed 102 can therefore include a generally variable quality of materials therein.

[0029] For the illustrated embodiment, the mixed plastic waste feed 102 is supplied to a feed preparation unit 104 or pretreatment section, which processes and separates components of the mixed plastic waste feed 102 into two or more streams based on differences between their respective qualities or compositions. In some examples, the feed preparation unit 104 includes a debaler, a shredder, a granulator, a washer, a dryer, a density-based separator, a centrifuge, a magnetic separator, a non-magnetic separator, or any suitable combination thereof. Additionally, the feed preparation unit 104 may include a first inlet to receive the mixed plastic waste feed 102, a first outlet to output a first waste stream 106 rich in PS and PVC, a second outlet to output a second waste stream 108 rich in PET, and a third outlet to output a polyolefin feed stream 110 rich in PE and PP. It should be understood that the feed preparation unit 104 may include any suitable number of inlets and outlets, each designed to receive or provide materials in solid and / or liquid forms. In an example, the polyolefin feed stream 110 may be separated from a remainder of the mixed plastic waste feed 102, such that the feed preparation unit 104 includes one outlet for the24CHEM0021 - WO-ORD9 polyolefin feed stream 110 and another outlet for the remainder of the mixed plastic waste feed 102

[0030] In some examples, the system 100 includes a first mechanical recycling unit 112 having a second inlet coupled to the first outlet of the feed preparation unit 104. The first mechanical recycling unit 112 can therefore receive the first waste stream 106 and produce a first processed stream 114 that is supplied from a fourth outlet of the first mechanical recycling unit 112. Similarly, the system 100 of certain examples includes a second mechanical recycling unit 116 with a third inlet coupled to the second outlet of the feed preparation unit 104 to receive the second waste stream 108. The second mechanical recycling unit 116 of certain examples therefore produces and outputs a second processed stream 118 from a fifth outlet of the second mechanical recycling unit 116. The first processed stream 114 is rich in PS and PVC material and the second processed stream 118 is rich in PET material. In some examples, one or both of the processed streams 114, 118 are stored in respective hoppers. Additionally, certain examples may include supplying a preselected portion, amount, or flow rate of one or both of the processed streams 114, 118 to be combined with the polyolefin feed stream 110, such as to ensure a constant and / or preselected feed quality. In certain cases, an additional polyolefin feed which is of substantially higher purity than the polyolefin feed stream 110 may be sourced externally and added to the polyolefin feed stream 110 to maintain constant feed quality to an extruder of the system 100.

[0031] In certain examples, the separated or segregated streams containing PVC, PS, and / or PET are mechanically recycled instead of chemically recycled to increase or maximize a value that can be regained from these materials. In some examples, removing the PVC, PS, and / or PET materials improves the quality of polyolefin feed stream 110 used to produce high-quality pyrolysis oil that is supplied to steam crackers. As such, the system 100 including the feed preparation unit 104 can ensure the polyolefin feed stream 110 is produced with a maintained, consistent composition or quality.

[0032] As illustrated, the system 100 includes a chemical recycling unit 120 positioned to receive the polyolefin feed stream 110 from the feed preparation unit 104. In examples, the chemical recycling unit 120 includes a fourth inlet coupled to the third outlet of the feed preparation unit 104. As described in detail below, the chemical recycling unit 120 converts or valorizes the polyolefin feed stream 110 into one or more hydrocarbon streams of increased value. In the illustrated example, the chemical recycling unit 120 includes a sixth outlet to output a light24CHEM0021 - WO-ORD10 pyrolysis oil stream 130 and a seventh outlet to output a heavy pyrolysis oil stream 132. The light pyrolysis oil stream 130 can then be supplied from the sixth outlet to a fifth inlet of a steam cracker 140, which produces an upgraded product stream 142 containing high value chemicals, such as ethene and propene.

[0033] In examples of the system 100 including a refinery 150, the heavy pyrolysis oil stream 132 is supplied from the seventh outlet into a sixth inlet of the refinery 150. The refinery 150 of certain examples produces a first refined stream 152 or circular feedstock that can be subsequently directed into a seventh inlet of the steam cracker 140. The first refined stream 152 contains C2, C3, or C4 saturated hydrocarbons, naphtha, diesel, or any combination thereof. In some examples, the refinery 150 additionally or alternatively utilizes the heavy pyrolysis oil stream 132 to produce a second refined stream 154 containing high value hydrocarbon products. In certain examples, a selected configuration of the chemical recycling unit 120 is determined based on the desired end products of the system 100. For instance, FIGS. 2 and 3 as described below illustrate two examples of the chemical recycling unit 120 suitable for systems 100 that respectively produce the light pyrolysis oil stream 130 or both the light pyrolysis oil stream 130 and the heavy pyrolysis oil stream 132.

[0034] FIG. 2 is a diagrammatic representation of a system 200 for receiving a polyolefin feed stream and producing pyrolysis oil with a desirably low boiling point based on the integration of a filtration unit upstream of two reactors or thermal cracking units. The system 200 of the illustrated example includes an extruder, a dechlorination unit, a filtration unit, a solids vessel, a first reactor or thermal cracking unit, a distillation unit, and a second reactor or thermal cracking unit. In examples, a polyolefin feed stream 202 is supplied into a first inlet of an extruder 204. As noted above, the polyolefin feed stream 202 can be produced or prepared from mixed plastic waste by a suitable feed preparation unit and is rich in high-quality PE and PP materials.

[0035] The extruder 204 can provide heat and compression to the polyolefin feed stream 202 to cause partial depolymerization of the PE and PP materials contained therein. The extruder 204 of certain examples is a devolatilization extruder that heats the materials therein to release vapor that is high in chlorine. For example, the partial depolymerization occurring in the extruder 204 produces a chlorine-rich gas stream 206 that is output from a first outlet of the extruder 204. In certain examples, the chlorine-rich gas stream 206 contains hydrochloric acid (HC1), chlorinated hydrocarbons, and / or other volatile components. The chlorine-rich gas stream 206 can be24CHEM0021 - WO-ORD11 withdrawn from the extruder 204 and routed to another portion of the system 200, such as a condensation and scrubbing system described herein.

[0036] The extruder 204 also produces a molten oligomer stream 208 having a reduced content of chlorine compared to the polyolefin feed stream 202 and outputs the molten oligomer stream 208 through a second outlet of the extruder 204. The molten oligomer stream 208 contains depolymerized PE and PP materials, which are molten or include a lower viscosity compared to the polyolefin feed stream 202. In some examples, the extruder 204 includes one or more single or twin screw extruders, augers, heated screw feeders, kneader reactors, and / or multi-stage heated pumps. In examples, the extruder 204 operates at a temperature ranging from about 200 to 450 °C. In some examples, the operating temperature ranges from about 300 to 450 °C. The extruder 204 of certain examples includes a residence time of about 10 minutes or about 5 minutes or lower

[0037] The molten oligomer stream 208 is supplied from the extruder 204 and into a second inlet of a dechlorination unit 210 or vessel that is coupled downstream of the extruder 204. The dechlorination unit 210 includes a scrubbing and condensation system that removes additional chlorines from the molten oligomer stream 208. The dechlorination unit 210 thus operates as a second stage of dechlorination. As such, a chlorine-rich fluid stream 214 containing gas and / or liquid is removed from a third outlet of the dechlorination unit 210. The dechlorination unit 210 can therefore output a dechlorinated molten oligomer stream 212 through a fourth outlet, which is supplied into a filtration unit 220 coupled downstream of the dechlorination unit 210.

[0038] In some examples, the chlorine-rich gas stream 206 from the extruder 204 is combined with the chlorine-rich fluid stream 214 from the dechlorination unit 210, and the compounds thereof are routed to gas condensation and then to a scrubber. The condensed hydrocarbons of the chlorine-rich liquid stream from the streams 206 and 214 can be recovered for further applications as chlorinated hydrocarbons or organochlorines or can be neutralized in contact with aqueous or alcoholic alkali solution to recover liquid hydrocarbon. In examples, the dechlorination unit 210 includes a residence time of up to about 2 hours. The dechlorination unit 210 can be operated at any suitable temperature for removing targeted chlorinated compounds. Additionally, the dechlorination unit 210 further reduces the viscosity of the oligomers therein, which can correspondingly increase filtration efficiency and / or reduce rejection in filtration cycles. In certain examples, the molecular weight of the dechlorinated molten oligomer stream 212 ranges between about 1650 and 30000 g / mol. Certain examples have a molecular weight between about 1650 and24CHEM0021 - WO-ORD1220000 g / mol or about 1650 and 10000 g / mol. The dechlorination unit 210 of examples herein reduce the viscosity of the feed to the filtration unit 220 to about 3000 millipascal-second (mPa s) or centipoise (cP) or lower, as measured at about 220 °C.

[0039] In examples, the filtration unit 220 has a third inlet to receive the dechlorinated molten oligomer stream 212 and produces a filtered oligomer stream 222 that is output through a fifth outlet of the filtration unit 220. The filtration unit 220 includes a heated melt filter that is sized and arranged to remove fillers, particulates, and / or other solids or contaminants from the dechlorinated molten oligomer stream 212, thereby producing the filtered oligomer stream 222. The filtration unit 220 can also output a first solid residue 224 containing removed materials and solids including heteroatoms from a sixth outlet, which directs the first solid residue 224 to a fourth inlet of a solids vessel 226 for storage or containment as potentially hazardous solid waste.

[0040] The heated melt filter of the filtration unit 220 may include a mesh or screen having openings through which oligomers of the filtered oligomer stream 222 can traverse, while undesired materials above a size threshold are retained and removed from the oligomers. In an example, the heated melt filter includes a pore size of about 3 microns to about 100 microns, and the filtered oligomer stream 222 is free or substantially free of solids greater than the pore size. In certain examples, the heated melt filter includes a continuous melt filter and the filtration unit 220 includes one or more online screen changing subsystems or components that facilitate efficient filter maintenance, suitable for operating with the viscosity of the dechlorinated molten oligomer stream 212. That is, the filtration unit 220 of some examples is selected for continuous operation with features for screen changing without interrupting operation of the filter. In examples, the heated melt filter alternatively or additionally includes a batch filter. The filtration unit 220 can include a single filter or a multistage filter arrangement, as detailed below.

[0041] For multistage operations, the heated melt filter may include multiple filters that have individually selected pore or opening sizes and are arranged in series, such as a first filter having a larger opening size followed by a second filter having a smaller opening size. As one example, the heated melt filter can direct the dechlorinated molten oligomer stream 212 through a first filter that provides coarse filtering of materials having a size of greater than 50 microns. The resulting filtrate from the first filter can then be directed though a second filter that provides fine filtering of materials having a size between 3 and 50 microns. This graduated method of filtering can be extended to any suitable number of filters-in-series, such as 2, 3, 4, 5, or more. Additionally, each24CHEM0021 - WO-ORD13 filter can be specifically sized to retain materials within a predetermined size range. As a nonlimiting example of three filters in series, a first filter can be sized to remove materials greater than 80 microns, a second filter can be sized to remove materials greater than 40 microns, and a third filter can be sized to remove materials greater than 3 microns. Examples of the filtration unit 220 employing filters ranging from coarse to fine can therefore enhance the operating efficiency of the system 200 by reducing pressure drop and / or enabling less frequent filter cleaning, among other benefits.

[0042] In the illustrated example, the filtration unit 220 supplies the filtered oligomer stream 222 into a fifth inlet of a first reactor 230. The first reactor 230 is a first thermal cracking unit or first thermal cracker, in some examples. As illustrated, the first reactor receives and thermally cracks the filtered molten oligomer stream 208 and produce a heavy cracked stream 232 and a first light cracked stream 234. In examples, the first reactor 230 includes a seventh outlet that outputs the heavy cracked stream 232 and an eighth outlet that outputs the first light cracked stream 234. In certain examples, the heavy cracked stream 232 and the first light cracked stream 234 can be referred to collectively as a cracked product stream, and the first reactor 230 supplies the first light cracked stream 234 as at least a portion of the cracked product stream for distillation as described below.

[0043] The first reactor 230 can be operated with either intermitted or continuous withdrawal of the heavy cracked stream 232. In examples, the first reactor 230 operates at a temperature ranging from about 350 to 450 °C. The first reactor 230 of some examples includes a residence time of up to about 2 hours. Each of the operating temperature and the residence time is selected to cause targeted thermal cracking of oligomers within the first reactor 230. The first reactor 230 can be or include a stirred tank reactor, a bubble column reactor with pump recirculation, a heated tubular reactor or a reactor with high heat transfer area with or without intermittent devolatilization, or a rotary kiln.

[0044] The system 200 includes a second reactor 240 having a sixth inlet to receive the heavy cracked stream 232 produced by the first reactor 230. In examples, the second reactor 240 is a second thermal cracking unit or second thermal cracker. Additionally, the second reactor 240 receives and thermally cracks the heavy cracked stream 232 to produce a second light cracked stream 244 and a second solid residue 246 or additional solid residue that contains removed materials and solids including heteroatoms.24CHEM0021 - WO-ORD14

[0045] The second solid residue 246 can be provided from a ninth outlet of the second reactor 240 and directed to a seventh inlet of the solids vessel 226, which can also receive the first solid residue 224 described above. Additionally, the second light cracked stream 244 is output from a tenth outlet of the second reactor 240. Examples of the system 200 utilizing a second reactor 240 for additional thermal cracking can increase pyrolysis oil yield by further producing valuable chemicals or monomers from the received oligomer material that remains uncracked after passing through the first reactor 230. In examples, the second reactor 240 operates at a temperature ranging from about 400 to 530 °C. In certain examples, the operating temperature of the second reactor 240 is higher than the operating temperature of the first reactor 230. The second reactor 240 of some examples includes a residence time of up to about 2 hours.

[0046] Furthermore, the illustrated example of the system 200 includes a distillation unit 250, fractionator, or separation zone that receives the first light cracked stream 234 from the first reactor 230 and the second light cracked stream 244 from the second reactor 240. In an example, the first light cracked stream 234 is received through an eighth inlet of the distillation unit 250 and the second light cracked stream 244 is received through a ninth inlet of the distillation unit 250, though these streams alternatively may be combined upstream of the distillation unit 250. The distillation unit 250 leverages the relative boiling points of the various chemical compounds to produce or isolate a pyrolysis oil product stream 260, which can be output from an eleventh outlet of the distillation unit 250.

[0047] In examples, the pyrolysis oil product stream 260 includes a final boiling point of about 350 °C or less. Moreover, the system 200 enables product cut streams to be withdrawn at any desired cut temperatures. As an example, a first cut can include an initial boiling point up to about 220 °C, a second cut can include boiling points between about 221 °C to 370 °C, and a third cut can include boiling points greater than about 370 °C. That is, the distillation unit can be configured to provide any desired final boiling point to the pyrolysis oil product stream 260, such as about 330 °C, 350 °C, 370 °C, or 400 °C for example.

[0048] In examples, the distillation unit 250 also includes a twelfth outlet to output a heavy distillate stream 262, which is routed or recycled to a tenth inlet of the second reactor 240. The second reactor 240 thus thermally cracks the heavy distillate stream 262 in combination with the heavy cracked stream 232 from the first reactor 230, thereby converting the heavier bottoms products into additional desired light products. Moreover, the process of conversion in the second24CHEM0021 - WO-ORD15 reactor 240 also facilitates additional removal of any residual chlorides and heteroatom contaminants like metals and non-metals, which are directed to the solids vessel 226. The distillation unit 250 can also include a thirteenth outlet to output a light gas stream 264 containing light gases, such as Ci-Ce hydrocarbons that are separated from the pyrolysis oil product stream 260 and can be efficiently integrated with a steam cracker. Thus, the system 200 operates as a chemical recycling unit that delivers continuous production of low-boiling, high-quality light pyrolysis oil for use in a steam cracker.

[0049] FIG. 3 is a diagrammatic representation of a system 300 for receiving a polyolefin feed stream and producing pyrolysis oil with a desirably low boiling point based on the integration of a filtration unit upstream of one reactor or thermal cracking unit. The system 300 of the illustrated example includes an extruder, a dechlorination unit, a filtration unit, a solids vessel, a thermal cracking unit, and a distillation unit. Each of these units can correspond to and include similar features as the units discussed above with respect to FIG. 2. These components are similarly labeled, and their descriptions are not repeated in detail for improved clarity. As shown, the system 300 alternatively includes the single thermal cracking unit downstream of the filtration unit for producing a pyrolysis oil product, instead of the two thermal cracking units described above. As compared to FIG. 2, the system of FIG. 3 supplies a product from the single reactor to a distillation unit, which produces a bottom or heavy stream for routing to a refinery and a top or light stream of pyrolysis oil for routing to a steam cracker.

[0050] In examples, the system 300 includes an extruder 304 to receive a polyolefin feed stream 302 into a first inlet and produce a molten oligomer stream 308 and a chlorine-rich gas stream 306. The molten oligomer stream 308 is output through a first outlet of the extruder 304 and the chlorine-rich gas stream is output through a second outlet of the extruder, in some examples. The molten oligomer stream 308 is then supplied into a second inlet of a dechlorination unit 310, which produces a dechlorinated molten oligomer stream 312 and a chlorine-rich fluid stream 314. The dechlorination unit 310 can output the dechlorinated molten oligomer stream 312 through a third outlet, while the chlorine-rich fluid stream 314 is output through a fourth outlet.

[0051] The system 300 includes a filtration unit 320 having a third inlet to receive the dechlorinated molten oligomer stream 312 and remove materials or fillers therefrom. The filtration unit 320 may output a solid residue 324 containing heteroatoms from a fifth outlet, which is separated from a filtered oligomer stream 322 output through a sixth outlet of the filtration unit24CHEM0021 - WO-ORD16320. The system 300 can include a solids vessel 326 having a fourth inlet to receive the solid residue 324 for storage or containment.

[0052] In some examples, the system 300 includes a reactor 330, thermal cracker, or thermal cracking unit having a fifth inlet to receive the filtered oligomer stream 322. The reactor 330 thermally cracks the filtered oligomer stream 322 to produce a cracked product stream 336. In examples, the reactor 330 operates at a temperature ranging from about 350 to 530 °C. For instance, the reactor 330 can operate at a temperature ranging from about 350 to 450 °C. In some examples, the reactor 330 operates at a temperature ranging from about 400 to 530 °C. The residence time of the reactor 330 is up to about 2 hours, in certain examples. Additionally, the reactor 330 can be or include a stirred tank reactor, a bubble column reactor with pump recirculation, a heated tubular reactor or a high heat transfer surface area reactor with or without intermittent devolatilization, or a rotary kiln. The reactor 330 of certain examples includes a seventh outlet to output the cracked product stream 336 to a sixth inlet of a distillation unit 350.

[0053] The distillation unit 350 can therefore separate or fractionate the cracked product stream 336 into various product streams based on their respective boiling point ranges. For instance, the distillation unit 350 of the illustrated example outputs a light pyrolysis oil product 360 from an eighth outlet, a heavy pyrolysis oil product 362 from a ninth outlet, and a light gas stream 364 from a tenth outlet. The light pyrolysis oil product 360, having a suitably low final boiling point, can thus be directed to a steam cracker for further production of desired chemical products. The heavy pyrolysis oil product 362 of certain examples is directed to a refinery for further utilization, as noted with respect to FIG. 1. In examples, the light pyrolysis oil product 360 includes a final boiling point of about 350 °C or less, and the heavy pyrolysis oil product 362 includes an initial boiling point of greater than about 350 °C.

[0054] As recognized herein, the chemical recycling units or systems represented by the system 200 of FIG. 2 and the system 300 of FIG. 3 efficiently reduce oligomer viscosity to resolve issues otherwise faced by the use of hot filtration of high viscosity melt. For example, the chemical recycling units disclosed herein reduce or minimize losses in filtration cycles by reducing the viscosity of feed to the filtration units to a predetermined threshold viscosity, such as about 5000 mPa s, about 3000 mPa s or less. In examples, the dechlorinated molten oligomer stream exiting the extruder generally includes a molecular weight of up to 50000 g / mol with a viscosity of up to 10000 mPa s. The integrated dechlorination or viscosity reduction steps utilized herein enable the24CHEM0021 - WO-ORD17 dechlorinated molten oligomer stream to be fed to the filtration unit and the filtration reject cycles produce a desirably lower quantity of contaminated purge material or solids. In other words, compared to other systems that may provide an extremely viscous melt to a filter and thus the filtration reject cycles would produce a higher quantity of highly contaminated purge material. This material is produced in such quantities that any subsequent cracking steps would increase the size requirement and corresponding costs, unlike the present disclosure that enables equipment size reduction based on the relatively low amount of purge materials delivered by significantly reducing or dropping melt viscosity in the dechlorination step.

[0055] As previously mentioned, an advantage of producing only plastic pyrolysis oil with a final boiling point of about 350 °C or less is that the pyrolysis oil can be completely vaporized in convection coils of the a steam cracker furnace. The complete vaporization enables full blending of the pyrolysis oil with any desired conventional liquid steam cracker feeds. Moreover, while certain crackers can only handle feeds with lower boiling end points, the pyrolysis oil can be appropriately cut to provide a particularly selected fraction for routing to the steam cracker, while a remaining heavy portion of the pyrolysis oil can be processed by a second reactor (as in FIG. 2) or diverted to a refinery (as in FIG. 3), producing additional desired products.

[0056] As a further advantage, the processing examples discussed above deliver a drastic reduction in heteroatoms, which is a continuous issue in mixed plastic waste recycling. The multistage heteroatom removal disclosed herein produces pyrolysis oil that is fully or partially decontaminated for steam cracker use. In examples of FIG. 2, the heavy pyrolysis oil either from the first reactor or the distillation unit is cracked further in the second reactor, which produces additional light products to be routed to the distillation unit, while remove removing heteroatoms as solids. In examples of FIG. 3, only certain products such as light pyrolysis oil are withdrawn from the reactor, which causes an efficient reduction or decrease of heteroatoms in the final pyrolysis oil product from the distillation unit. Additionally, the pyrolysis oil produced herein has high stability for storage and / or transportation, based on its decontamination or low amounts of heteroatoms. In examples disclosed herein, the yield of produced pyrolysis oil is at least about 85, 90, or 95 wt. %, such as based on the significant reduction of losses to coke or gases.

[0057] FIG. 4 is a diagrammatic representation of a control system 400 for controlling operation of the systems discussed above. The control system 400 includes at least one controller 401. Each controller 401 includes at least one processor 402, which may be or include a central processing24CHEM0021 - WO-ORD18 unit (CPU), a graphics processing unit (GPU), a co-processing unit, a sub-processing unit, or any other suitable electronic data processor. Each controller 401 includes at least one memory 403, which may be or include random access memory (RAM), read-only memory (ROM), or any other suitable electronic memory or storage. For the illustrated embodiment, the controller 401 is communicatively connected to or in signal communication with each unit, component, and / or equipment present in a particular implementation of the systems discussed above. For example, the controller 401 can be communicatively coupled to a depolymerization unit 404 (such as a devolatilization extruder), a dechlorination unit 410, a filtration unit 420, a thermal cracking unit 430, and a distillation unit 450, in some examples. In certain examples, the controller 401 can be communicatively coupled to a depolymerization unit 404, a dechlorination unit 410, a filtration unit 420, a first thermal cracking unit 430, a second thermal cracking unit 430, and a distillation unit 450. In certain examples, the controller 401 is further communicatively coupled to a solids holds vessel and / or controllable features thereof. The controller 401 can further be communicatively connected to any other elements that are included in or facilitate operation of the systems discussed above. The communicative connection between the controller 401 and the various zones and devices enables the controller 401 to receive monitoring and operational data from sensors and / or sub-controllers of each of these units, zones, or devices present in the embodiments discussed above, and further enables the controller 401 to provide control signals (e.g., electrical signals, instructions, data packets) to modify the operation of each of these units, zones, or devices.

[0058] For example, the controller 401 may receive monitoring data from sensors (e.g., temperature sensors, pressure sensors, flow sensors) of the depolymerization unit 404 and / or the dechlorination unit 410. Based on any predefined threshold values for certain operational parameters, the controller 401 provides suitable control signals to modify the operation of the depolymerization unit 404, the dechlorination unit 410, or any components thereof to ensure that these components operate within the temperatures, pressures, and residence times disclosed above. The controller 401 of certain examples receives monitoring data from sensors (e.g., temperature sensors, pressure sensors, flow sensors) of the filtration unit 420, and based on predefined threshold values for certain operational parameters, provides suitable control signals to modify the operation of the filtration unit 420 or components thereof to enable operation in accordance with any predefined threshold values.24CHEM0021 - WO-ORD19

[0059] Moreover, the controller 401 may receive monitoring data from sensors (e.g., temperature sensors, pressure sensors, flow sensors) of one or more thermal cracking units 430, and based on predefined threshold values for certain operational parameters, provide suitable control signals to modify the operation of one or more components of the thermal cracking units 430 to ensure that the thermal cracking units 430 operate within the temperatures, pressures, and residence times disclosed above. In examples, the controller 401 receives monitoring data from sensors (e.g., temperature sensors, pressure sensors, flow sensors) of the distillation unit 450, and based on predefined threshold values for certain operational parameters, provides suitable control signals to modify the operation of the distillation unit 450 or components thereof to enable operation in accordance with any predefined threshold values.

[0060] In examples, the controller 401 instructs the various components of the systems discussed above to produce one or more desired pyrolysis oil products, such as based on the interoperation of components of the control system 400. For example, the controller 401 can control one or more of the systems described above to perform (i) depolymerization of a polyolefin feed stream rich in PE and PP to produce a molten oligomer stream and a chlorine-rich gas stream, (ii) dechlorination of the molten oligomer stream to produce a dechlorinated molten oligomer stream and a chlorine- rich fluid stream, (iii) filtration of the dechlorinated molten oligomer stream through a heated melt filter having a pore size ranging between about 3 pm and 100 pm to produce a filtered molten oligomer stream and a solid residue containing heteroatoms, (iv) thermal cracking of the filtered molten oligomer stream to produce a cracked product stream, (v) distillation of at least a portion of the cracked product stream to produce a pyrolysis oil product stream having a final boiling point of about 350 °C or less and a heavy distillate stream, and (vi) provision of the pyrolysis oil product stream for steam cracking.

[0061] In certain examples, the controller 401 can also control the system to perform (vii) separation of the cracked product stream into a first light cracked stream and a heavy cracked stream, in which the at least a portion of the cracked product stream provided for distillation includes the first light cracked stream, (viii) thermal cracking of the heavy cracked stream and the heavy distillate stream to produce a second light cracked stream and an additional solid residue containing heteroatoms, (ix) distillation of the second light cracked stream along with the first light cracked stream to produce the pyrolysis oil product stream and the heavy distillate stream, and (x) recycling of the heavy distillate stream for thermal cracking with the heavy cracked stream.24CHEM0021 - WO-ORD20EXAMPLES

[0062] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices and / or methods claimed herein are made and evaluated and, therefore, are intended to be purely exemplary and are not intended to limit the disclosure. Efforts have been made to ensure accuracy with respect to numbers (such as amounts, temperatures, and so forth), but some deviations should be accounted for.

[0063] There are numerous variations and combinations of reaction conditions, for example, component concentrations, desired solvents, solvent mixtures, temperatures, pressures and other reaction ranges and conditions that can be used to optimize the product purity and yield obtained from the described process. Only reasonable and routine experimentation will be required to optimize such process conditions.

[0064] Example 1: Density based separation of waste plastic

[0065] The methods and systems disclosed herein can efficiently separate, process, and upgrade mixed plastic waste into high-quality pyrolysis oil having low levels of contaminants. As nonlimiting examples, experiments were performed to evaluate the separation of waste plastic based on density to generate a polyolefin-rich feed and components for mechanical recycling. The experimental data provided multiple findings with respect to the density -based separation.

[0066] For example, performed experiments separated waste plastic materials based on differences between their densities when added to a vessel or tank containing a liquid. A mixed plastic waste feed was provided having a combination of PE, PP, PS, and PVC. Density-based separation was performed using water, which caused 98% of PE and PP materials to float, while PS and PVC materials were settled at the bottom.

[0067] The floating PE and PP material is efficiently separated from the remaining PS and PVC material and dried, thereby forming a polyolefin-rich feed suitable for pyrolysis. Additionally, the settled mixture of PS and PVC was subjected to water having a modified density. For example, salt was added to increase the density of the water, which caused separation of the PS from the PVC material. In particular, more than 95% of PS material was floating over the salted water layer, while PVC material was settled in the bottom. This process of adjusting the salinity and density of water was continued to achieve greater than 99% efficiency in separation of PS and PVC materials, which produced suitable feedstocks for respective grades of mechanical separation.24CHEM0021 - WO-ORD21

[0068] Example 2: Yields utilizing the example system illustrated in FIG. 2

[0069] An experiment was performed to analyze the yields of the example system 200 of FIG.2. A continuous trial was performed using a polyolefin feed stream at a flow rate of 10.0 kilograms per hour (kg / h). The flow rates of streams included in the trial are illustrated in Table 1 below.

[0070] Table 1 : Flow rates of various streams

[0071] The system produced a pyrolysis oil product stream of steam cracker-grade having a final boiling point (FBP) maximum of up to 350 °C with a flow rate of 8.5 kg / h. Additionally, the pyrolysis oil product stream included less than 10 ppm of chlorides. As such, the system produced steam cracker grade pyrolysis oil liquid with a yield of 85%. In examples including this unit at a steam cracker site, the total usable hydrocarbons for cracking (including gases) is between 95- 97%.

[0072] Example 3: Yields utilizing the example system illustrated in FIG. 3

[0073] An experiment was performed to analyze the yields of the example system 300 of FIG. 3. A continuous trial was performed using a polyolefin feed stream at a flow rate of 10.0 kilograms per hour (kg / h). The flow rates of streams included in the trial are illustrated in Table 2 below.

[0074] Table 2 : Flow rates of various streams24CHEM0021 - WO-ORD22

[0075] The system produced a steam cracker-grade pyrolysis oil product stream with a flow rate of 5.8 kg / h. The pyrolysis oil product stream includes a final boiling point maximum of up to 350 °C and includes less than 10 ppm of chlorides. The system also produced a heavy pyrolysis oil product stream of refinery grade, having a final boiling point above 350 °C, at a flowrate of 3.1 kg / hr. The system thus produced an overall liquid product yield of 89% from the plastic feed. In examples including this unit present at a steam cracker and refinery site, the total usable hydrocarbons for cracking (including gases) is between 96-98%.

[0076] Example 4: Advantages of integrating dechlorination unit upstream of filtration unit

[0077] Further analysis was performed regarding the integration of two-stage dechlorination performed upstream of filtration. As described in Examples 2 and 3 above, a first part of chlorinated material removed in the devolatilization extruder while a second part of the chlorinated material is removed in the dechlorination vessel.

[0078] In reference systems lacking the dechlorination unit, product from the extruder is directly subjected to pyrolysis in the downstream pyrolysis reactor, which causes higher concentration of chlorides in the resulting pyrolysis oil. This effect is observable in certain existing commercial pyrolysis oil processes. Additionally, chloride material present in the pyrolysis oil is in the organic chloride form and thus difficult and costly to remove or separate out.

[0079] In an experiment, a similar plastic feed composition having greater than 1000 ppm of chlorides was charged to a system including a dechlorination unit as disclosed herein and a reference system lacking a dechlorination unit. For the reference system, the steam cracker grade pyrolysis oil included a chlorides content of up to 600 ppm. For the system including a dechlorination unit, the steam cracker grade pyrolysis oil included a significantly lower chlorides content of up to 20 ppm. In examples, the chlorides content is less than 10 ppm.24CHEM0021 - WO-ORD23

[0080] Performance of dechlorination at low temperature helps in removing chlorines in the form of inorganic chlorides, such as HC1 and salts that can be efficient to remove via alkali scrubbers and filters respectively. Integration of the dechlorination unit with the filtration unit disclosed herein enables production of final pyrolysis oil having less than 10 ppm of chlorides, despite the plastic feed having greater than 1000 ppm of chlorides initially.

[0081] Example 5: Blendability of plastic pyrolysis oil

[0082] In an experiment, various commercial grade pyrolysis oils were subjected to a hydrotreater and then analyzed for blendability with the naphtha feed of a steam cracker. Due to fouling tendency of heavy or high molecular weight components in the convection section tubes of the steam cracker, the blendability of existing pyrolysis oil is limited based on its final boiling point. In particular, an analysis was performed regarding the blending percent of pyrolysis oil with the main naphtha feed of a steam cracker. In examples, the blendability is variable based on steam cracker design and maximum tube metal temperature designs available in steam crackers.

[0083] Full range pyrolysis oil having a final boiling of 445 °C (or full range) was hydrotreated. However, the hydrotreated pyrolysis oil can be blended at a ratio of up to 9% with the regular liquid feed of a steam cracker. In contrast, light pyrolysis oil having a final boiling of 350 °C as produced by systems herein can be hydrotreated and blended at up to 100% with the regular liquid feed of a steam cracker. This experiment validated that the pyrolysis oil developed by this process can be provided to a hydrotreater and then fully blended, without any fouling issues in the liquid steam cracker.

[0084] Other objects, features and advantages of the disclosure will become apparent from the foregoing figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments of the disclosure, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from the detailed description. In further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any of the other embodiments. In further embodiments, additional features may be added to the specific embodiments described herein.

Claims

1. 24CHEM0021 - WO-ORD24Claims1. A method, comprising: depolymerizing a polyolefin feed stream rich in polyethene (PE) and poly(l -methylethylene) (PP) to produce a molten oligomer stream and a chlorine-rich gas stream; dechlorinating the molten oligomer stream to produce a dechlorinated molten oligomer stream and a chlorine-rich fluid stream; filtering the dechlorinated molten oligomer stream through a heated melt filter having a pore size ranging between about 3 micrometers (pm) and 100 pm to produce a filtered molten oligomer stream and a solid residue containing heteroatoms; thermally cracking the filtered molten oligomer stream to produce a cracked product stream; distilling at least a portion of the cracked product stream to produce a pyrolysis oil product stream having a final boiling point of about 350 degrees Celsius (°C) or less and a heavy distillate stream; and supplying the pyrolysis oil product stream for steam cracking.

2. The method of claim 1, further comprising: separating the cracked product stream into a first light cracked stream and a heavy cracked stream, wherein the at least a portion of the cracked product stream provided for distillation comprises the first light cracked stream; thermally cracking the heavy cracked stream and the heavy distillate stream to produce a second light cracked stream and an additional solid residue containing heteroatoms; and distilling the second light cracked stream along with the first light cracked stream to produce the pyrolysis oil product stream and the heavy distillate stream; and recycling the heavy distillate stream for thermal cracking with the heavy cracked stream.

3. The method of claim 1, wherein the at least a portion of the cracked product stream provided for distillation comprises an entirety of the cracked product stream, and wherein the method further comprises supplying the heavy distillate stream for refining at a refinery.

4. The method of any of claims 1-3, further comprising removing the solid residue from the heated melt filter continuously.

5. The method of any of claims 1-3, further comprising removing the solid residue from the heated melt filter intermittently.24CHEM0021 - WO-ORD256. The method of any of claims 1-5, wherein the heated melt filter comprises a multi-stage filter.

7. The method of any of claims 1-6, wherein the depolymerizing comprises operating a devolatilization extruder at a temperature ranging from about 200 °C to 450 °C with a residence time of about 10 minutes or less.

8. The method of any of claims 1-7, wherein the dechlorinating comprises operating a dechlorination unit with a residence time of about 2 hours or less, and wherein the dechlorinated molten oligomer stream comprises oligomers with a molecular weight ranging from about 1650 grams per mole (g / mol) to 10000 g / mol.

9. The method of any of claims 1-8, further comprising producing the polyolefin feed stream before depolymerizing the polyolefin feed stream by separating a mixed waste plastic stream into the polyolefin feed stream and one or more plastic streams rich in poly(l -phenyl ethylene) (PS), poly(l -chloroethylene) (PVC), polyethylene terephthalate) (PET), or a combination thereof.

10. A system, comprising: a devolatilization extruder configured to receive a polyolefin feed stream rich in polyethene (PE) and poly(l -methylethylene) (PP) and produce a molten oligomer stream and a chlorine-rich gas stream; a dechlorination unit configured to receive the molten oligomer stream and produce a dechlorinated molten oligomer stream and a chlorine-rich fluid stream; a filtration unit comprising a heated melt filter and configured to receive the dechlorinated molten oligomer stream and produce a filtered molten oligomer stream and a first solid residue containing heteroatoms; a first thermal cracking unit configured to receive the filtered molten oligomer stream and produce a first light cracked stream and a heavy cracked stream; a second thermal cracking unit configured to receive the heavy cracked stream and a heavy distillate stream and produce a second light cracked stream and a second solid residue containing heteroatoms; and a distillation unit configured to: receive the first light cracked stream and the second light cracked stream;24CHEM0021 - WO-ORD26 produce the heavy distillate stream routed to the second thermal cracking unit and a pyrolysis oil product stream having a final boiling point of about 350 degrees Celsius (°C) or less; and route the pyrolysis oil product stream to a steam cracker.

11. The system of claim 10, wherein the heated melt filter comprises a pore size ranging between about 3 micrometers (pm) and 100 pm.

12. The system of claims 10 or 11, wherein the heated melt filter comprises a multi-stage filter.

13. The system of any of claims 10-12, wherein the first solid residue is continuously removed from the filtration unit, and wherein the second solid residue is removed continuously from the second thermal cracking unit.

14. The system of any of claims 10-13, further comprising a feed preparation zone positioned upstream of the devolatilization extruder to prepare the polyolefin feed stream, wherein the feed preparation zone comprises a debaler, a shredder, a granulator, a washer, a dryer, a density -based separator, a centrifuge, a magnetic separator, or a combination thereof.

15. The system of any of claims 10-14, wherein the devolatilization extruder comprises one or more single or twin screw extruders, augers, heated screw feeders, kneader reactors, multi-stage heated pumps, or a combination thereof, and wherein the dechlorination unit comprises a condensation and scrubbing system.

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