Systems and methods for treatment of mixed plastic medical waste prior to pyrolysis

Abstract

Systems and methods presented herein facilitate the processing of mixed plastic medical waste (MPMW) into pyrolysis oil. Embodiments of the systems and methods enable MPMW to be treated by a single treatment unit and / or single treatment step that facilitates at least sterilization, agglomeration, densification, and heteroatom removal of the MPMW, thereby to yield pre-pyrolysis treated MPMW (PPT-MPMW) that is better suited for pyrolysis than untreated MPMW. Relative to MPMW, the PPT-MPMW may be mostly or entirely free of biological or medicinal contaminants, may have a substantially higher density, and may be mostly or entirely free of heteroatom contaminants. As such, the PPT-MPMW reduces or eliminates the risk of inadvertent exposure to biological or medicinal agents, improves the efficiency of pyrolysis oil production, reduces or eliminates the risk of damage to pyrolysis oil production and / or processing equipment that results from heteroatom content, and improves the stability of the resulting pyrolysis oil.

Description

24CHEM0025-WO-ORD1SYSTEMS AND METHODS FOR TREATMENT OF MIXED PLASTIC MEDICAL WASTE PRIOR TO PYROLYSISTECHNICAL FIELD

[0001] The present disclosure generally relates to systems and methods for treating and pyrolyzing mixed plastic medical waste (MPMW), thereby to yield pyrolysis oil. More specifically, the present disclosure relates to systems and methods for treating MPMW prior to pyrolysis to disinfect the MPMW by removing biogenic contaminants, to improve the efficiency of the pyrolysis process, to reduce the risk of damage to the pyrolysis unit and other pyrolysis oil processing equipment, and to improve the quality of the resulting pyrolysis oil.BACKGROUND

[0002] Mixed plastic medical waste includes any number of disposable polymeric materials that are used for medical applications. Examples of MPMW include disposable medical wraps, disposable syringes, disposable pill bottles, disposable intravenous (IV) bags, disposable otoscope tips, disposable thermometer covers, disposable specula, disposable plastic tongue depressors, and / or disposable plastic covers for bedding or other medical equipment. Furthermore, in addition to medical products themselves, even the packaging of such medical products may be considered and handled as medical waste, especially when the medical product is removed from the packaging in a patient’s room or an operating theater, which results in additional MPMW. Given that surfaces of the MPMW may contain viruses, bacteria, biological fluids, medicines, and so forth, regulations often restrict at least certain MPMW (e.g., pill bottles) from being directly recycled to produce new plastic products due to the risk of contamination. As a result, the vast quantity of MPMW is disposed of within landfills or incinerators. Therefore, the remains a need to develop improved techniques for efficiently and effectively transforming MPMW into useful products.SUMMARY

[0003] Pyrolysis oil generally originates from the chemical recycling of mixed plastic waste. For example, pyrolysis oil can be formed by pyrolyzing mixed plastic waste at sufficiently elevated temperatures (e.g., between 400 °C and 500 °C) under anaerobic conditions. While it may be desirable to convert MPMW into useful pyrolysis oil, as opposed to the disposal options discussed24CHEM0025-WO-ORD2 above, Applicant has recognized that certain aspects of MPMW can make it problematic for pyrolysis, as well as treatment and processing techniques to address these issues.

[0004] One issue relates to the aforementioned biological and / or chemical contaminants that may be present on surfaces of the MPMW, which may require a pyrolysis processing facility to take additional precautions when storing, transporting, and processing MPMW relative to other mixed plastic waste streams, for example, to prevent inadvertent exposure of personnel to such contaminants. Another issue relates to density, as certain MPMW (e.g., medical wraps) may be implemented as low-density polymer sheets. As such, it can be difficult to load sufficient quantities of this type of low-density polymer material efficiently into a pyrolysis unit to efficiently produce pyrolysis oil. Yet another issue relates to heteroatom content within the MPMW. In general, it is desirable for mixed plastic waste that is pyrolyzed to contain mostly or entirely hydrocarbons, as heteroatoms (e.g., chlorine, oxygen, nitrogen, silicon) can cause issues in equipment used to produce or subsequently process the pyrolysis oil and / or cause issues with respect to the stability of the resulting pyrolysis oil. For example, MPMW can contain polyvinylchloride (PVC), among other polymers. PVC, as well as other chlorinated polymers, can release corrosive hydrogen chloride gas (HC1) during pyrolysis or during subsequent hydrotreatment and / or cracking of pyrolysis oil formed from PVC, which can lead to undesirable corrosion issues in pyrolysis, hydrotreatment, and / or cracking reactors. Additionally, heteroatoms that remain in the pyrolysis oil can reduce the stability of the pyrolysis oil and promote the formation of gum deposits when the pyrolysis oil is stored and / or transported, which undesirably increases the time, cost, and complexity of cleaning storage and / or transport containers.

[0005] With the foregoing in mind, Applicant has devised systems and methods to facilitate the treatment and processing of MPMW into pyrolysis oil that address or mitigate the aforementioned issues related to pyrolyzing MPMW. For example, in some embodiments, the systems and methods discussed herein enable MPMW to be treated by a single treatment unit and / or single treatment step that facilitates at least sterilization, agglomeration, densification, and heteroatom removal of the MPMW, thereby to yield pre-pyrolysis treated MPMW (PPT-MPMW) that is better suited for pyrolysis than untreated MPMW. For example, relative to MPMW, the PPT-MPMW may be mostly or entirely free of biological or medicinal contaminants, may have a substantially higher density, and may be mostly or entirely free of heteroatoms. As such, relative to a process involving the production of pyrolysis oil directly from MPMW, the PPT-MPMW reduces or eliminates the24CHEM0025-WO-ORD3 risk of inadvertent exposure to biological or medicinal agents, improves the efficiency of pyrolysis oil production, reduces or eliminates the risk of damage to pyrolysis oil production and / or processing equipment, and improves the stability of the resulting pyrolysis oil.

[0006] Embodiments include systems and methods for treatment and processing of MPMW into pyrolysis oil. An embodiment of one such system includes a system for processing MPMW. The system includes a pre-pyrolysis treatment unit (PPTU) including a shearing element configured to receive and treat the MPMW by applying a shearing force that heats the MPMW via friction, in which the heat facilitates sterilization, agglomeration, densification, pelletization, heteroatom removal, or any combination thereof, during treatment of the MPMW, thereby to yield pre- pyrolysis-treated MPMW (PPT-MPMW). The system further includes a pyrolysis unit configured to receive and pyrolyze the PPT-MPMW, thereby to yield pyrolysis oil.

[0007] In some embodiments, the shearing element of the PPTU is mechanically connected to at least one motor that is configured to rotate at least a portion of the shearing element to generate the shearing force to heat the MPMW via friction. In some embodiments, the shearing element includes a rotating drum and a non-rotating body of the PPTU, and the rotating drum and the nonrotating body are separated by a gap. In some embodiments, the shearing element includes two counter-rotating disks separated by a gap. In some embodiments, an interior of the PPTU is configured to be pressurized to a pressure greater than atmospheric pressure to enhance the sterilization and / or the heteroatom removal during treatment of the MPMW. In some embodiments, the PPTU includes a purge gas inlet configured to receive a purge gas and an exhaust gas outlet configured to allow the purge gas and exhaust gases released from the MPMW during heating to exit the PPTU. In some embodiments, the purge gas includes air, an inert gas, or steam. In some embodiments, the exhaust gases include hydrogen chloride (HC1), hydrogen cyanide (HCN), acetic acid (AcOH), ammonia (NH3), carbon monoxide (CO), carbon dioxide (CO2), or any combination thereof.

[0008] In some embodiments, the PPTU includes a liquid water inlet configured to receive water to enhance the sterilization of the MPMW, the heteroatom removal from the MPMW, or both, during the treatment of the MPMW. In some embodiments, the water enhances thermal transfer and uniform heating of the MPMW during the treatment. In some embodiments, at least a portion of the water is converted into steam by the heating of the MPMW, and the steam enhances the sterilization of the MPMW, the heteroatom removal from the MPMW, or both, during the24CHEM0025-WO-ORD4 treatment of the MPMW. In some embodiments, at least a portion of the water is configured to dissolve or suspend compounds containing heteroatoms released from the MPMW during the treatment, and the PPTU includes a drain outlet configured to allow the portion of the water to exit the PPTU along with the dissolved or suspended compounds. In some embodiments, the one or more heteroatoms include chlorine, oxygen, nitrogen, silicon, or any combination thereof. In some embodiments, the MPMW includes polypropylene (PP), polyvinylchloride (PVC), polyacrylonitrile (PAN), polyamide (PA), ethylene-vinyl acetate (EVA), cellulose, or any combination thereof.

[0009] An embodiment of one such method includes a method of processing MPMW. The method includes the step of performing a pre-pyrolysis treatment of the MPMW, in which the prepyrolysis treatment includes applying a shearing force that heats the MPMW via friction to facilitate sterilization, agglomeration, densification, pelletization, heteroatom removal, or any combination thereof, thereby to yield pre-pyrolysis-treated MPMW (PPT-MPMW). The method includes the step of pyrolyzing the PPT-MPMW under anerobic conditions, thereby to yield pyrolysis oil.

[0010] In some embodiments, prior to performing the pre-pyrolysis treatment, the method includes the step of analyzing a composition of the MPMW and determining at least one operational parameter of the pre-pyrolysis treatment based at least in part on the composition of the MPMW, the at least one operational parameter including a rotational rate of a shearing element, a treatment temperature range, a flow rate or temperature of water introduced into the pre-pyrolysis treatment, or a flow rate or temperature of a purge gas introduced into the pre-pyrolysis treatment, or any combination thereof. In some embodiments, the pre-pyrolysis treatment facilitates the sterilization of the MPMW, the agglomeration of the MPMW, the densification of the MPMW, the pelletization of the MPMW, and heteroatom removal from the MPMW in a single treatment step.

[0011] In some embodiments, the step of applying the shearing force heats the MPMW to temperatures greater than about 100 degrees Celsius (°C) and less than about 400 °C to at least partially melt the MPMW. In some embodiments, the step of applying the shearing force includes activating a motor mechanically connected to at least one shearing element to apply the shearing force to heat the MPMW via friction. In some embodiments, the pre-pyrolysis treatment includes mixing the MPMW with water before, during, and / or after heating the MPMW, in which the water24CHEM0025-WO-ORD5 enhances the sterilization of the MPMW, the heteroatom removal from the MPMW, or both, during the pre-pyrolysis treatment of the MPMW, and the water is in liquid form, gaseous form, or a combination of liquid and gaseous form. In some embodiments, the pre-pyrolysis treatment includes mixing the MPMW with a purge gas before, during, and / or after heating the MPMW, in which the purge gas enhances the heteroatom removal from the MPMW. In some embodiments, the pre-pyrolysis treatment includes directing an exhaust gas stream produced from heating the MPMW to an exhaust gas scrubber capable of removing at least one exhaust gas from the exhaust gas stream, and in which the at least one exhaust gas includes hydrogen chloride (HC1), hydrogen cyanide (HCN), acetic acid (AcOH), ammonia (NH3), carbon monoxide (CO), carbon dioxide (CO2), or any combination thereof.

[0012] 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.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] 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.24CHEM0025-WO-ORD6

[0014] FIG. 1 is a diagrammatic representation of a system for treating and processing mixed plastic medical waste into pyrolysis oil, according to an embodiment.

[0015] FIG. 2 is a diagrammatic representation of a pre-pyrolysis treatment unit (PPTU), according to an embodiment.

[0016] FIGS. 3A and 3B illustrate alternative shearing element designs for use in the PPTU, according to an embodiment.

[0017] FIG. 4 is a diagrammatic representation of a method by which the system of FIG. 1 processes MPMW to yield pyrolysis oil, according to an embodiment.

[0018] FIG. 5 is a diagrammatic representation of a method by which the PPTU treats the MPMW to generate pre-pyrolysis-treated MPMW (PPT-MPMW), according to an embodiment.

[0019] FIG. 6 is a diagrammatic representation of a control system of the system of FIG. 1, according to an embodiment.

[0020] FIG. 7 is a graphical representation of the results of a first model study in which the decomposition of ethylene-vinyl acetate (EVA) was modeled at different treatment temperatures, according to an embodiment.

[0021] FIG. 8 is a graphical representation of the results of a second model study in which the decomposition of cellulose was modeled at different treatment temperatures, according to an embodiment.

[0022] FIG. 9 is a graphical representation of the results of a third model study in which the decomposition of polyvinylchloride (PVC) was modeled at different treatment temperatures, according to an embodiment.DETAILED DESCRIPTION

[0023] The present disclosure describes various embodiments related to systems and methods for treating and processing mixed plastic medical waste, thereby to yield pyrolysis oil. 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 term “plurality” as used herein refers to two or more items or components. The terms “about” or “approximately” are defined as being close to as understood by one of ordinary skill in the art. In one non-limiting24CHEM0025-WO-ORD7 embodiment, these terms are defined to be within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

[0024] 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 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, which includes the component. In a nonlimiting example, 10 grams of component in 100 grams of the material is 10 wt.% of component.

[0025] FIG. 1 is a diagrammatic representation of an embodiment of a system 100 for treating and processing mixed plastic medical waste 102. The system 100 generally treats and converts batches of MPMW 102 into pyrolysis oil 104. The MPMW may include a number of different polymeric materials. A non-limiting list of example polymeric materials that may be present within MPMW includes: polypropylene (PP), polyethylene (PE) (e.g., high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE)), polyvinylchloride (PVC), polyacrylonitrile (PAN), polyamide (PA), ethylene-vinyl acetate (EVA), and cellulose. For example, in some embodiments, the MPMW may include or be predominantly or entirely comprised of non-woven, disposable, low-density polypropylene medical wraps. In some embodiments, the MPMW may include, but is not limited to: disposable syringes, disposable pill bottles, disposable IV bags, disposable otoscope tips, disposable thermometer covers, disposable specula, disposable plastic tongue depressors, and / or disposable plastic covers for bedding or other medical equipment, as well as the disposable polymer packaging of these (and other, potentially non-disposable) medical products. The MPMW may be collected from a medical facility (e.g., a hospital, doctor’s office, surgery center, physical therapy center, a diagnostic or laboratory testing facility, a wellness clinic), a dental facility, an optical care facility, a pharmaceutical facility, a cryo-treatment facility, an acupuncture facility, or other suitable facility. Due to being medical waste, the MPMW may include organic or biological materials, such as bodily fluids (e.g., blood, saliva, urine, feces, skin oils, lymphatic fluid) or medicines / drugs.24CHEM0025-WO-ORD8

[0026] For the embodiment illustrated in FIG. 1, the system 100 includes a MPMW analyzer 106 that is arranged to receive and analyze the composition of the MPMW 102 such that operational parameters of the system 100 can be configured to suitably treat and process the MPMW. The MPMW analyzer 106 may include a single analysis device or a collection of analysis devices that perform physical measurements (e.g., optical measurements, thermal measurements, spectroscopy measurements) of the MPMW 102 to determine information about the nature of the MPMW 102. For example, in some embodiments, the MPMW analyzer 106 may determine relative amounts of one or more polymeric materials present within the MPMW 102. In some embodiments, the MPMW analyzer 106 may additionally or alternatively determine other physical properties of the MPMW 102, such as the density of the MPMW, an average melting point or melting point range of the MPMW, an average decomposition temperature or decomposition temperature range of the MPMW, and / or decomposition products expected to be released when the MPMW decomposes. In some embodiments, the MPMW analyzer 106 may be omitted to reduce the complexity and / or improve the throughput or efficiency of the system 100. For such embodiments, the MPMW 102 may be separately (e.g., manually) analyzed in advance of treatment, and / or the operational parameters of the system 100 may be manually configured to accommodate MPMW 102 having particular compositions or ranges of compositions based on the known compositions of the MPMW.

[0027] For the embodiment illustrated in FIG. 1, the system 100 includes a pre-pyrolysis treatment unit (PPTU) 108 that is designed to treat and prepare the MPMW 102 for pyrolysis. The PPTU 108 is generally designed to facilitate sterilization, agglomeration, densification, pelletization, and / or heteroatom removal of the MPMW. In some embodiments, the PPTU 108 is designed to facilitate all of these treatment aspects in a single treatment step. As discussed in greater detail below, the PPTU 108 generally applies a shearing force to the MPMW 102, which creates sufficient friction (e.g., between pieces of the MPMW and contact faces of shearing elements and / or between pieces of the MPMW) to heat the material to temperatures greater than about 100 °C and less than about 400 °C (e.g., temperatures from about 100 °C to about 350 °C). Within this treatment temperature range, the removal of biogenic contaminants and the sterilization of the MPMW can be achieved. The PPTU 108 heats at least a portion of the polymeric materials (e.g., hydrocarbon polymers, such as PP) present within the MPMW 102 to at least a melting temperature range, which facilitates agglomeration and densification of the material. Depending24CHEM0025-WO-ORD9 on the composition of the MPMW 102, the PPTU 108 may heat another portion of polymeric materials (e.g., certain heteroatom-containing polymers, such as PVC, PAN, PA, EVA) to at least a decomposition temperature range, which may facilitate the release of certain heteroatoms (e.g., chlorine, oxygen, nitrogen, silicon) as components of volatile gases or solid compounds that are separated from the remainder of the MPMW, thereby reducing or eliminating the heteroatom content of the MPMW 102. In an example embodiment, prior to treatment in the PPTU 108, the MPMW 102 may have a particular heteroatom content, such as a chloride content ranging from about 100 part-per-million (ppm) to 3000 ppm, an oxygen content ranging from about 0.5 wt. % to about 8 wt. %, a nitrogen content from about 0.3 wt. %, and / or a silicon content ranging from about 100 ppm to about 200 ppm, such that after treatment, an amount of one or more of these heteroatoms present in the MPMW decreases.

[0028] In some embodiments, the PPTU 108 may introduce water (e.g., liquid water, steam) into the PPTU 108 to enhance thermal transfer to promote heating of the MPMW and / or to extract water-soluble heteroatom compounds (e.g., compounds including chlorine or silicon) or salts (e.g., ammonium salts) from the remainder of the MPMW. In some embodiments, the MPMW 102 may include cellulose or other polymeric materials that release water vapor during decomposition, which may provide some or all of the water to the PPTU 108 during operation. As a result of the treatment, the MPMW 102 leaves the PPTU 108 as pre-pyrolysis-treated MPMW (PPT-MPMW) 110 having an enhanced density, a reduced or eliminated heteroatom content, and / or a reduced or eliminated biological content, and in which the PPT-MPMW is desirably in the form of small plastic pellets that are more conducive to efficient and effective pyrolysis. In some embodiments, the PPT-MPMW 110 may immediately proceed to further processing. In other embodiments, the PPT-MPMW 110 may be stored for later processing or transported to another facility for further processing, in which the PPT-MPMW 110 is more easily stored and / or transported as a result of the undesired components of the MPMW 102 being removed by the treatment within the PPTU 108

[0029] For the embodiment illustrated in FIG. 1, the system 100 includes a PPT-MPMW analyzer 112 designed to analyze the composition of the PPT-MPMW 110 before the material advances to the pyrolysis. In some embodiments, the PPT-MPMW analyzer 112 may measure one or more of the properties that the MPMW analyzer 106 measures for the MPMW 102, as discussed above. For example, the PPT-MPMW analyzer 112 may analyze the density of the PPT-MPMW24CHEM0025-WO-ORD10110 to ensure that the density is greater than a predetermined density threshold value (e.g., from about 0.300 grams per cubic centimeter (g / cm3) to about 0.500 g / cm3) to determine that the treatment was successful. In some embodiments, the PPT-MPMW analyzer 112 may additionally or alternatively analyze the chemical composition of the PPT-MPMW 110 to determine the respective amounts of one or more heteroatoms (e.g., chlorine, oxygen, nitrogen, silicon) remaining in the PPT-MPMW after treatment, such that the respective amounts may be compared to respective predetermined heteroatom limits to ensure that the heteroatom content of the PPT- MPMW 110 is less than these predetermined heteroatom limits before proceeding to pyrolysis. For certain situations in which the density of the PPT-MPMW analyzer 112 is determined to be too low or the heteroatom content of the PPT-MPMW analyzer 112 is determined to be too high, the PPT-MPMW 110 may be routed back to the PPTU 108 for further treatment, as indicated by the arrow 114. For example, during a first treatment within the PPTU 108, the MPMW may be heated in the presence of a substantial quantity of liquid water to facilitate the reduction or elimination of a first heteroatom content (e.g., silicon), and during a second treatment within the PPTU 108, the material may be heated in the absence of liquid water to facilitate higher treatment temperatures to facilitate the reduction or elimination of a second heteroatom content (e.g., chlorine, nitrogen). In other embodiments, the PPT-MPMW analyzer 112 may be omitted to reduce the cost and complexity of the system 100, and the PPT-MPMW 110 may advance to pyrolysis without further analysis.

[0030] For the embodiment illustrated in FIG. 1, the system 100 includes a pyrolysis unit 116 that is designed to receive and pyrolyze the PPT-MPMW 112, thereby to yield the pyrolysis oil 104. More specifically, the pyrolysis unit 116 heats the PPT-MPMW 112 to temperatures ranging from about 400 °C to about 500 °C under anerobic conditions. Even when the MPMW 102 includes a substantial chloride content, it is presently recognized that the PPT-MPMW 112 has a substantially lower chloride content than the MPMW 102 (e.g., at least 25% lower, at least 50% lower, or at least 75% lower chloride content by weight) as a result of the treatment in the PPTU 108, and therefore the PPT-MPMW 112 releases substantially less corrosive HC1 gas during pyrolysis in the pyrolysis unit 116 than would be released if the MPMW 102 were pyrolyzed without this treatment. With suitable residence time and treatment temperature, the amount of other heteroatom species (e.g., oxygen, nitrogen, silicon) may also be substantially lower (e.g., at least 25% lower, at least 50% lower, or at least 75% lower by weight) as a result of the treatment in the24CHEM0025-WO-ORD11PPTU 108. As such, the treatment techniques disclosed herein advantageously decreases corrosion and extends the operational lifetime of the pyrolysis unit 116, as well as other equipment (e.g., hydrotreaters, steam crackers) that may be used to subsequently process the resulting pyrolysis oil 104. Additionally, as noted, the lower heteroatom (e.g., chlorine, oxygen, nitrogen, silicon) content of the PPT-MPMW 112 results in the production of pyrolysis oil 104 that also possesses a lower heteroatom content that would be present if the MPMW 102 were pyrolyzed without the prepyrolysis treatment, which enables the pyrolysis oil 104 to remain stable in a container for weeks to months (e.g., up to six months) during transport or storage without substantial gum formation.

[0031] For the embodiment illustrated in FIG. 1, the system 100 includes a controller 118 that is designed to monitor and control aspects of operation of the system 100. The controller 118 is discussed in greater detail with respect to FIG. 6. For the embodiment illustrated in FIG. 1, the controller 118 is communicatively connected to components of the system 100, such as the MPMW analyzer 106, the PPTU 108, and the PPT-MPMW analyzer 112, to receive data from sensing elements of these components and to provide control signals to modify operational parameters of these components based on the received data. For example, in some embodiments, the MPMW analyzer 106 may analyze the composition of the MPMW 102 and provide this compositional data to the controller 118, such that the controller 118 can determine operational parameters (e.g., rotational speeds, treatment temperature range, flow rate and / or temperature of water, flow rate or temperature of the purge gas, treatment time) for treating the MPMW 102, and then provide control signals to the PPTU 108 to implement these operational parameters during MPMW treatment. For an example embodiment, the operational parameters may include rotational speeds ranging from about 500 revolutions per minute (RPM) to about 1000 RPM, a treatment temperature ranging from about 100 °C to about 400 °C, a water temperature of about 100 °C, and a treatment time ranging from about 5 minutes to about 50 minutes. In another example, in some embodiments, the PPT-MPMW analyzer 112 may analyze the composition of the PPT-MPMW 110 and provide this compositional data to the controller 118, such that the controller 118 can determine operational parameters for additional treatment of the PPT-MPMW 110, and then provide control signals to the PPT-MPMW analyzer 112 to route the partially treated PPT-MPMW back to the PPTU 108 (as indicated by arrow 114), as well as control signals to the PPTU 108 to implement these operational parameters during a subsequent treatment of the PPT-MPMW. In other embodiments, the system 100 may omit the controller 118 to reduce the cost and / or24CHEM0025-WO-ORD12 complexity of the system 100, and the operational parameters of the PPTU 108 may be determined and manually implemented by a human operator.

[0032] FIG. 2 is a diagrammatic representation of an embodiment of a pre-pyrolysis treatment unit (PPTU) 108. It may be appreciated that the embodiment of the PPTU 108 illustrated in FIG. 2 is merely provided as an example, and in other embodiments, the PPTU 108 may include other features and / or different arrangements of features relative to the illustrated example. The illustrated embodiment of the PPTU 108 is generally designed to operate at least one shearing element to apply shear force that heats batches of MPMW 102 via friction, in which this heat facilitates melting, sterilization, agglomeration, densification, pelletization, and / or heteroatom removal during the pre-pyrolysis treatment.

[0033] For the embodiment illustrated in FIG. 2, the PPTU 108 includes a body 200, which may be fabricated of steel or another suitable material. Batches of MPMW 102 may be loaded into the body 200 of the PPTU 108, and then a cover 202 may then be sealed over the top of the body 200. In some embodiments, the cover 202 may be sealed over the top of the body 200 to enable the interior of the PPTU 108 to be pressurized above atmospheric pressure (e.g., between 1 bar gauge (barg) and 2 barg) by the heating of the MPMW 102 and / or the introduction of a purge gas (e.g., steam) during treatment, for example, to enhance the effect of steam on sterilization and / or heteroatom removal. For the illustrated embodiment, the PPTU 108 includes a drum 204 that is driven by a variable frequency drive (VFD) 206 or other suitable motor, which enables the drum 204 to rotate within the body 200 at different rotational speeds. The rotational motion of the drum 204 creates a centrifugal force that drives the MPMW 102 toward the outer edges of the drum 204, while the force of gravity further drives the MPMW 102 to enter the gap 208 between the rotating drum 204 and the body 200 of the PPTU 108. As such, for the illustrated embodiment, the combination of the rotating drum 204 and the non-rotating body 200 forms the shearing element of the PPTU 108. As the MPMW 102 enters the gap 208, shearing force is applied to the MPMW 102 via contact with the body 200 and the rotating drum 204. This shearing force has a number of effects on the MPMW 102. For example, for pieces of the MPMW that are larger than the gap 208, the MPMW may be shredded by the shearing force into smaller pieces that can subsequently enter gap 208. Once the MPMW enters the gap, the shearing force results in substantial friction between pieces of the MPMW and the surfaces of the shearing element, as well as between pieces of the MPMW itself, which quickly heats to the MPMW to a temperature that is within a melting24CHEM0025-WO-ORD13 temperature range of at least a portion of the MPMW. This heating facilitates disinfection or sterilization of the MPMW and promotes the decomposition of biological or organic contaminants (e.g., biogenic contaminants) within the MPMW. As the at least partially melted pieces of the MPMW collide within the gap, they agglomerate and densify, while the width 210 of the gap 208 prevents the agglomerated and densified pieces of the MPMW from growing too large in size, resulting in the formation of plastic pellets. As a width 212 of the gap between the drum 204 and the body 200 increases below the drum 204, the plastic pellets are driven by the force of gravity to exit the PPTU 108 as PPT-MPMW 110.

[0034] It may be appreciated that the various polymers present in a batch of MPMW may have different melting and decomposition temperature profiles. For example, PP melts in a temperature range from about 130 °C to about 170 °C, and decomposes in a temperature range from about 300 °C to about 500 °C. PVC melts in a temperature range from about 100 °C to about 260 °C, and decomposes in a temperature range from about 135 °C to about 200 °C to release at least hydrogen chloride (HC1) gas. PAN melts at a temperature of about 300 °C, and decomposes at a temperature range from about 280 °C to about 450 °C, in which decomposition involves the release of at least nitrogen-containing gases (e.g., hydrogen cyanide (HCN), ammonia (NH3)). PA melts at temperatures greater than about 330 °C and decomposes at temperatures ranging from about 380 °C to about 490 °C. EVA melts at temperatures ranging from about 65 °C to about 110 °C, and decomposes at temperatures ranging from about 300 °C to about 350 °C, in which decomposition involves the release of at least acetic acid (AcOH). Cellulose decomposes at temperatures ranging from about 315 °C to about 370 °C, involving the release of at least water vapor, while other common components of cellulose may decompose at lower temperatures, such as hemicellulose decomposition at about 220 °C and lignin decomposition at about 160 °C. The skilled artisan will appreciate that the aforementioned melting and decomposition temperatures are representative for certain implementations of these polymeric materials. In some cases, the melting and / or decomposition temperatures of certain polymeric materials may vary due to, for example, the addition of co-polymers and / or additives or environmental conditions (e.g., presence of acids, bases, and / or water / steam). As such, in some embodiments, the PPTU 108 functions to heat the MPMW to a temperature range from about 100 °C to about 350 °C, for example, to facilitate at least partial melting of the MPMW, as well as a reduction in the heteroatom content of the MPMW.24CHEM0025-WO-ORD14

[0035] With the foregoing in mind, the embodiment of the PPTU 108 illustrated in FIG. 2 includes additional features to facilitate the treatment of the MPMW 102, and in particular, to facilitate removal of heteroatom species. As noted, the shearing force provided between the rotating drum 204 and the body 200 of the PPTU 108 induces friction that heats the MPMW 102, and for certain types of polymeric materials, this is sufficient to heat at least a portion of the MPMW 102 into a decomposition temperature range that promotes the release of heteroatoms from these partially decomposing polymeric materials. For example, as noted, once heated to a sufficiently high temperature, certain polymeric materials may release certain heteroatoms as volatile gases (e.g., HC1, HCN, NH3, AcOH, CO, CO2), such that the PPT-MPMW 110 that exits the PPTU 108 is mostly or entirely a hydrocarbon material with a diminished or eliminated heteroatom content. Because certain of these volatile gases are reactive, in some embodiments, the PPTU 108 includes a purge gas inlet 214 fluidly connected to a purge gas source 216 that is designed to deliver a stream of a purge gas into the body 200 of the PPTU 108 to purge from the body 200 gases (e.g., heteroatom-containing gases) that are released during melting and / or decomposition of polymeric materials of the MPMW 102 during treatment. In some embodiments, the purge gas may be air, an inert gas (e.g., N2, CO2), steam, or any combination thereof. For the illustrated embodiment, the exhaust gases exit the body 200 of the PPTU 108 via an exhaust gas outlet 218 to enter an exhaust gas scrubber 220 containing one or more exhaust gas treatment stages for removing at least a portion of the exhaust gases from the exhaust gas stream. For example, the exhaust gas scrubber 220 may include an acid gas treatment stage in which the exhaust gas stream is exposed to a mixture of sodium hydroxide and sodium hypochlorite that reacts with and captures HC1, HCN, AcOH, or other acid gases within the exhaust stream. In some embodiments, the introduction of the purge gas into the body 200 of the PPTU 108 may result in the interior of the body 200 maintaining a pressure that is at or above atmospheric pressure (e.g., from about 1 bar gauge (barg) to about 2 barg) during treatment.

[0036] For the embodiment illustrated in FIG. 2, the PPTU 108 also includes a liquid water inlet 222 that is fluidly connected to a water source 224 to receive a stream of liquid water. In some embodiments, the water may be at a temperature ranging from about room temperature to about 95 °C. In some cases, the water may be introduced into the body 200 of the PPTU 108 to enhance thermal transfer between pieces of the MPMW 102, promoting a more even heating of the material. Additionally, as the water is heated to or beyond its boiling point, the resulting steam also24CHEM0025-WO-ORD15 facilitates the sterilization of the MPMW 102. In some embodiments, the amount of water introduced into the body 200 of the PPTU 108 and the temperatures within the body 200 of the PPTU 108 may result in substantially all of the water being converted into steam that eventually exits the body 200 via the exhaust gas outlet 218. However, in some embodiments, it is recognized that certain heteroatoms (e.g., silicon additives) and certain byproducts of the treatment (e.g., water-soluble salts) may be removed by contact (e.g., washing) with liquid water, and as such, a greater volume of liquid water may be introduced into the body 200 of the PPTU 108 via the liquid water inlet 222. For such embodiments, the PPTU 108 may include a drain outlet 226 that enables excess liquid water to exit the body 200 of the PPTU 108 under the force of gravity, carrying with it one or more of these byproducts. For example, the drain outlet 226 may be covered by a screen or mesh that enable liquid water to enter the outlet, while solid pellets of the PPT-MPMW 110 are blocked from entering the drain outlet 226. In some embodiments, the liquid water that exits the body 200 of the PPTU 108 via the drain outlet 226 may be provided as input to a water treatment unit 228 having one or more treatment stages (e.g., meshes, filters, chemical treatments, activated carbon) designed to remove these dissolved or suspended components from the water stream, which may enable ready recycling or disposal of the water stream.

[0037] For the embodiment illustrated in FIG. 2, the PPTU 108 also includes the controller 118 that is communicatively connected to various components of the PPTU 108 to monitor operational conditions and to provide control signals to modify operational parameters of components of the PPTU 108. For example, the controller 118 may be communicatively connected to receive temperature measurements from a temperature sensor 230 that is positioned to measure a temperature of the MPMW 102 at or near the shearing element during operation of the PPTU 108. The controller 118 may be communicatively connected to provide control signals to the VFD 206 to control the rotational speed and torque of the drum 204 during operation of the PPTU 108. The controller 118 may be communicatively connected to provide control signals to the water source 224 and the purge gas source 216 to control the flow of fluids into the PPTU 108. The controller 118 may also be communicatively connected to the exhaust gas scrubber 220 and the water treatment unit 228 to receive information on contaminants removed from the MPMW 102 as one technique for monitoring the progress of the treatment operation.

[0038] It may be appreciated that the body 200 and drum 204 of the PPTU 108 illustrated in FIG. 2 is merely provided as an example shearing element design, and in other embodiments, the24CHEM0025-WO-ORD16PPTU 108 may apply the shearing force to heat the MPMW 102 via friction using different shearing element designs. That is, instead of the combination of the rotating drum 204 of the embodiment illustrated in FIG. 2, in other embodiments, the shearing force may be applied using a shearing element having counter-rotating shearing disks, as illustrated in FIGS. 3A and 3B. For example, FIG. 3A illustrates an embodiment of a shearing element 300A that includes a first shearing disk 302 mechanically connected to a first shaft 304 and a second shearing disk 306 mechanically connected to a second shaft 308. The first shaft 304 is connected to a first motor (not shown) that is configured to rotate the first shaft 304 and the first shearing disk 302 in a first direction, while the second shaft 308 is connected to a second motor (not shown) that is configured to rotate the second shaft 308 and the second shearing disk 306 in a second direction that is opposite the first direction. Additionally, the counter-rotating shearing disks 302, 306 are separated by a gap 310. As such, the gap 310 between the counter-rotating shearing disks 302, 306 illustrated in FIG. 3 A functions similar to the gap 208 of the example PPTU 108 illustrated in FIG. 2 to apply a shearing force that heats MPMW 102 via friction to facilitate the treatment of the MPMW, thereby to yield the PPT-MPMW 110.

[0039] FIG. 3B illustrates another embodiment of a shearing element 300B that includes a first set of shearing disks 320 mechanically connected to a first shaft 322 and a second set of shearing disks 324 mechanically connected to a second shaft 326. The first shaft 322 is connected to a first motor (not shown) that is configured to rotate the first shaft 322 and the first set of shearing disks 302 in a first direction, while the second shaft 326 is connected to a second motor (not shown) that is configured to rotate the second shaft 326 and the second set of shearing disks 324 in a second direction that is opposite the first direction. Additionally, the counter-rotating sets of shearing disks 320, 324 are separated by a gap 328. As such, the gap 328 between the counter-rotating sets of shearing disks 320, 324 illustrated in FIG. 3B functions similar to the gap 208 of the example PPTU 108 illustrated in FIG. 2 to apply a shearing force that heats MPMW 102 via friction to facilitate the treatment of the MPMW, thereby to yield the PPT-MPMW 110. It may be appreciated that, while the embodiments of the shearing elements discussed herein may perform some initial shredding of the MPMW during operation, the disclosed shearing elements lack blades that are typically incorporated into rotary shredding mechanisms, which reduces the complexity and the maintenance of the shearing elements and desirably promotes closer contact and enhanced thermal24CHEM0025-WO-ORD17 transfer between the MPMW and the shearing elements to enhance the frictional heating of the MPMW.

[0040] FIG. 4 is a diagrammatic representation of an embodiment of a method 400 by which the system 100 illustrated in FIG. 1 processes MPMW to yield pyrolysis oil. The method 400 is discussed with reference to elements illustrated in FIGS. 1 and 2. In other embodiments, the method 400 may include additional steps, omitted steps, repeated steps, and so forth, relative to the embodiment illustrated in FIG. 4. In some embodiments, one or more of the steps of the method 400 may be stored as instructions in a memory and executed by a processor of the controller 118.

[0041] For the embodiment illustrated in FIG. 4, the method 400 begins with the step 402 of collecting or receiving the MPMW. As noted, the MPMW may be collected from various facilities that utilize disposable plastic items while providing medical, pharmaceutical, dental, optical, diagnostic, or other health-related services to patients, and the collected MPMW may be delivered to a site that hosts some of all of the components of the system 100. In some embodiments, the method 400 includes the optional step 404 of water washing and / or shredding the MPMW. For example, this optional step may be performed before or after the MPMW is delivered to a site hosting some or all of the components of the system 100 and may be performed to facilitate the transportation or storage of the MPMW prior to treatment and pyrolysis. In some embodiments, the step 404 may be omitted to simplify and / or reduce the operational cost, energy consumption, and / or water consumption associated with performing the method 400.

[0042] In some embodiments, the method 400 includes the optional step 406 of analyzing the composition of the MPMW and determining operational parameters for operating the PPTU based at least in part on the composition of the MPMW. For the embodiment illustrated in FIG. 4, the method 400 includes the step 408 of treating the MPMW in the PPTU, thereby to yield PPT- MPMW. For example, in some embodiments, the system 100 includes the MPMW analyzer that measures the types and quantities of polymeric materials present within the MPMW, and then provides this compositional information to the controller 118. Responsive to receiving this information, the controller 118 may determine operational parameters that the PPTU 108 should use to effectively treat the MPMW and provide control signals to the components (e.g., the VFD 206, the water source 224, the purge gas source 216) of the PPTU 108 to implement these operational parameters during treatment of the MPMW. For example, the operational parameters may include, but are not limited to: a rotational rate of the shearing element(s), a treatment24CHEM0025-WO-ORD18 temperature of the MPMW, a flow rate or temperature of the water from the water source 224, or a flow rate or temperature of the purge gas from the purge gas source 216, or any combination thereof.

[0043] In some embodiments, the method 400 includes the optional step 410 of analyzing the composition of the PPT-MPMW and optionally determining operational parameters for operating the PPTU for an additional treatment based at least in part on the composition of the PPT-MPMW. In some embodiments, the system 100 includes the PPT-MPMW analyzer 112 that measures properties of the PPT-MPMW such that the controller 118 can determine, for example, whether the density is sufficiently high and the heteroatom content sufficiently low to proceed to pyrolyzing the PPT-MPMW. Responsive to the controller 118 determining, for example, that the density of below a predetermined density threshold value and / or a heteroatom content is greater than a corresponding predetermined heteroatom content threshold value, the controller 118 may provide suitable control signals to direct the initially treated PPT-MPMW back to the PPTU 108 for further treatment, as indicated by the arrow 412. Furthermore, the controller 118 may modify the operational parameters of the treatment, such that the second treatment within the PPTU 108 occurs at a different rotational rate that enables a different (e.g., higher or lower) temperature range, with a different flow rate or temperature of the water and / or the purge gas, to further treat the PPT-MPMW to increase the density beyond the predetermined density threshold and / or decrease the content of the heteroatoms below the corresponding predetermined heteroatom content threshold value. In some embodiments, the step 410 may be omitted and the PPT-MPMW may proceed directly to pyrolysis after treatment. For the illustrated embodiment, the method 400 concludes with the step 414 of providing the PPT-MPMW to the pyrolysis unit and pyrolyzing the PPT-MPMW, thereby to yield pyrolysis oil.

[0044] FIG. 5 is a diagrammatic representation of an embodiment of a method 500 by which the PPTU 108 treats the MPMW to generate PPT-MPMW. The method 500 is discussed with reference to elements illustrated in FIGS. 1 and 2. In other embodiments, the method 500 may include additional steps, omitted steps, repeated steps, and so forth, relative to the embodiment illustrated in FIG. 5. In some embodiments, one or more of the steps of the method 500 may be stored as instructions in a memory and executed by a processor of the controller 118. The method 500 begins with the step 502 of introducing the MPMW into the PPTU. For example, as shown in FIG. 2, a batch of MPMW may be loaded inside the body 200 of the PPTU 108, and then the cover24CHEM0025-WO-ORD19202 may be connected to the top of the body 200 to contain the MPMW therein for treatment. In other embodiments, instead of being a batch treatment unit, the PPTU may be a continuous treatment unit that may receive and convert a stream of MPMW into a stream of PPT-MPMW.

[0045] For the embodiment illustrated in FIG. 5, the method 500 continues with the step 504 of activating the shearing element(s) of the PPTU to apply shearing force that heats the MPMW via friction, the heat facilitating sterilization, agglomeration, densification, pelletization, and / or heteroatom removal. For example, for the embodiment illustrated in FIG. 2, the controller 118 may provide suitable control signals to the VFD 206 to cause the drum 204 to rotate relative to the body 200 to provide the requisite shearing force to the MPMW. As discussed with respect to FIGS. 3A and 3B, in other embodiments, other shearing elements may be used to apply the shearing force to the MPMW. In some embodiments, the method 500 includes the optional step 506 of introducing water, a purge gas, or a combination of both, into the PPTU. As noted herein, in some embodiments, the water and / or purge gas may, in combination with the frictional heating generated by the shearing force, facilitate the melting, the sterilization, and / or heteroatom removal during the MPMW treatment. In some embodiments, the controller 118 may introduce the water and / or purge gas into the PPTU for thermal management purposes, such as improving thermal contact and / or thermal transfer between pieces of the MPMW during treatment and / or regulating the maximum temperature within the PPTU during treatment. The method 500 includes the step 508 of directing exhaust gas stream produced from heating the MPMW within the PPTU to an exhaust gas scrubber capable of at least treating one or more exhaust gases (e.g., HC1, HCN) present within the exhaust gas stream. For example, this step may include neutralizing and removing one or more acid gases (e.g., HC1, HCN, AcOH, CO2) and / or basic gases (e.g., NH3) from the exhaust stream. In some embodiments, the steps 504, 506, and 508 may be implemented concurrently during treatment of the MPMW.

[0046] For the illustrated embodiment, the method 500 concludes with the step 510 of providing the PPT-MPMW from the PPTU for subsequent pyrolysis. As noted, relative to the MPMW prior to treatment, the PPT-MPMW is sterilized, denser, and pelletized, which makes the PPT-MPMW easier to handle, store, and transport than the MPMW. In some embodiments, the PPT-MPMW may be stored or transported to another location for later pyrolysis. In other embodiments, the PPT-MPMW may immediately proceed to pyrolysis after treatment within the PPTU. As noted, relative to the MPMW, the higher density, the lower heteroatom content, and the pelletized form24CHEM0025-WO-ORD20 of the PPT-MPMW is more conducive for effective and efficient pyrolysis, reduces the risk of damage to the pyrolysis unit and / or other pyrolysis oil processing equipment, and produces pyrolysis oil with greater stability (e.g., lower gum formation).

[0047] FIG. 6 is a diagrammatic representation of an embodiment of a control system 600 of the system 100. In some examples, the control system 600 includes at least the controller 118. While described herein as a controller, it may be appreciated by those skilled in the art that, in other embodiments, the controller 118 may be or include any suitable computing system, such as a desktop, laptop, or tablet computing device. Additionally, while the control system 600 is illustrated and described as including a single controller 118, in some embodiments, the operation of the controller may instead be implemented through use of a plurality of controllers of the control system 600 in signal communication with one another, e.g., distributed, in series, or supervisory to sub-component controllers, among others, as will be understood by those skilled in the art.

[0048] The controller 118 of various examples disclosed herein includes one or more processors, such as processor 602, as well as a memory or machine-readable storage medium, such as memory 604. As used herein, a “machine-readable storage medium” may be, for example, any electronic, magnetic, optical, or other physical storage apparatus to contain or store information such as executable instructions, data, and the like. For example, any machine-readable storage medium described herein may be any of random-access memory (RAM), volatile memory, non-volatile memory, flash memory, a storage drive, a hard drive, a solid-state drive, any type of storage disk, and the like, or a combination thereof. The memory 604 stores or includes instructions executable by the processor 602. As used herein, a “processor” includes, for example, one processor or multiple processors included in a single device or distributed across multiple computing devices. The processor 602 may be at least one of a central processing unit (CPU), a semiconductor-based microprocessor, a graphics processing unit (GPU), a field-programmable gate array (FPGA) to retrieve and execute instructions, a real-time processor (RTP), other electronic circuitry suitable for the retrieval and execution instructions stored on a machine-readable storage medium, or a combination thereof.

[0049] The controller 118 includes an input / output (I / O) interface 606 that enables the controller to be in signal communication with other components associated with the system 100 and / or the PPTU 108. For example, these components may include the MPMW analyzer 106, the PPTU 108, and / or the PPT-MPMW analyzer 112, as discussed above with respect to FIG. 1. The components24CHEM0025-WO-ORD21 may include components of PPTU 108, such as the VFD 206, purge gas source 216, exhaust gas scrubber 220, water source 224, water treatment unit 228, and / or temperature sensor 230, as discussed above with respect to FIG. 2. As used herein, “signal communication” refers to electric communication such as hard wiring two components together or wireless communication, as understood by those skilled in the art. For example, wireless communication may be Wi-Fi®, Bluetooth®, ZigBee, or forms of near field communications, as will be understood by those skilled in the art. In addition, signal communication may include one or more intermediate controllers or relays disposed between elements that are in signal communication with one another.

[0050] For the embodiment illustrated in FIG. 6, the memory 604 of the controller 118 includes a PPTU control module 608 including instructions executed by the processor 602 to facilitate the treatment of MPMW into PPT-MPMW, according to the examples disclosed herein. For example, in some embodiments, the PPTU control module 608 may include instructions to facilitate some or all of the steps of the method 400 illustrated in FIG. 4. In some embodiments, the PPTU control module 608 may additionally or alternatively include instructions to facilitate some or all of the steps of the method 500 illustrated in FIG. 5.

[0051] Model studies were performed to evaluate the effectiveness of the pre-pyrolysis treatment at decreasing the heteroatom content of different heteroatom-containing polymers that may be present within the MPMW. In a first model study represented in FIG. 7, EVA polymer was modeled as being heated to different temperatures (i.e., 300 °C, 310 °C, 320 °C) as part of a treatment operation within the PPTU. More specifically, the graph of FIG. 7 plots the modeled concentration of acetic acid (i.e., in grams per cubic centimeter (g / cm3)) released as the EVA polymer decomposes at the different temperatures as a function of time. As illustrated, the concentration of acetic acid rises more quickly over time at higher treatment temperatures, indicating that higher temperatures favor the decomposition of EVA and the release of oxygen heteroatoms as acetic acid. Because acetic acid has a boiling point of 117 °C, the acetic acid released from the EVA readily vaporizes and is purged from the PPTU, effectively reducing the heteroatom content of the EVA-containing medical waste during treatment.

[0052] In a second model study represented in FIG. 8, cellulose polymer was modeled as being heated to different temperatures (i.e., 300 °C, 310 °C, 320 °C) as part of a treatment operation within the PPTU. More specifically, the graph of FIG. 8 plots the moles of water released as the cellulose polymer decomposes at the different temperatures as a function of time. As illustrated,24CHEM0025-WO-ORD22 amount of water released rises more quickly over time at higher treatment temperatures, indicating that higher temperatures favor the decomposition of cellulose and the release of oxygen heteroatoms as water. Because water has a boiling point of 100 °C, the water released from the cellulose readily vaporizes and is eventually purged from the PPTU, effectively reducing the heteroatom content of the cellulose-containing medical waste during treatment. Additionally, as noted herein, the released water may also beneficially impact the treatment operation, for example, by enhancing the sterilization of the medical waste, enhancing the removal of other heteroatomcontaining compounds, and / or enhancing thermal transfer during the treatment operation.

[0053] In a third model study represented in FIG. 9, PVC polymer was modeled as being heated to different temperatures (i.e., 300 °C, 310 °C, 320 °C) as part of a treatment operation within the PPTU. More specifically, the graph of FIG. 9 plots the amount of HC1 gas (i.e., in grams) released as the PVC polymer decomposes at the different temperatures as a function of time. As illustrated, amount of HC1 released rises more quickly over time at higher treatment temperatures, indicating that higher temperatures favor the decomposition of PVC and the release of chlorine heteroatoms as HC1 gas. As noted, the HC1 released from the PVC is purged from the PPTU, effectively reducing the heteroatom content of the PVC-containing medical waste during treatment.

[0054] 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

24CHEM0025-WO-ORD23CLAIMSWhat is claimed is:

1. A system for processing mixed plastic medical waste (MPMW), the system comprising: a pre-pyrolysis treatment unit (PPTU) including a shearing element configured to receive and treat the MPMW by applying a shearing force that heats the MPMW via friction, the heat facilitating sterilization, agglomeration, densification, pelletization, heteroatom removal, or any combination thereof, during treatment of the MPMW, thereby to yield pre-pyrolysis-treated MPMW (PPT-MPMW); and a pyrolysis unit configured to receive and pyrolyze the PPT-MPMW, thereby to yield pyrolysis oil.

2. The system of claim 1, wherein the shearing element of the PPTU is mechanically connected to at least one motor that is configured to rotate at least a portion of the shearing element to generate the shearing force to heat the MPMW via friction.

3. The system of claim 2, wherein the shearing element comprises a rotating drum and a nonrotating body of the PPTU, wherein the rotating drum and the non-rotating body are separated by a gap.

4. The system of claim 1, wherein an interior of the PPTU is configured to be pressurized to a pressure greater than atmospheric pressure to enhance the sterilization and / or the heteroatom removal during treatment of the MPMW.

5. The system of claim 1, wherein the PPTU comprises a purge gas inlet is configured to receive a purge gas and an exhaust gas outlet configured to allow the purge gas and exhaust gases released from the MPMW during heating to exit the PPTU.24CHEM0025-WO-ORD246. The system of claim 1, wherein the PPTU comprises a liquid water inlet configured to receive water to enhance the sterilization of the MPMW, the heteroatom removal from the MPMW, or both, during the treatment of the MPMW.

7. The system of claim 6, wherein at least a portion of the water is supplied to dissolve or suspend compounds containing heteroatoms released from the MPMW during the treatment, and wherein the PPTU comprises a drain outlet configured to allow the portion of the water to exit the PPTU along with the dissolved or suspended compounds.

8. The system of claim 1, wherein the MPMW comprises polyethylene, low-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, polyvinylchloride, polyacrylonitrile, polyamide, ethylene-vinyl acetate, cellulose, or any combination thereof.

9. A method of processing mixed plastic medical waste (MPMW), the method comprising: performing a pre-pyrolysis treatment of the MPMW, the pre-pyrolysis treatment including applying a shearing force that heats the MPMW via friction to facilitate sterilization, agglomeration, densification, pelletization, heteroatom removal, or any combination thereof, thereby to yield pre-pyrolysis-treated MPMW (PPT-MPMW); and pyrolyzing the PPT-MPMW under anerobic conditions, thereby to yield pyrolysis oil.

10. The method of claim 9, wherein, prior to performing the pre-pyrolysis treatment, the method comprises: analyzing a composition of the MPMW and determining at least one operational parameter of the pre-pyrolysis treatment based at least in part on the composition of the MPMW, wherein the at least one operational parameter comprises a rotational rate of a shearing element, a treatment temperature range, a flow rate or temperature of water introduced into the pre-pyrolysis treatment, or a flow rate or temperature of a purge gas introduced into the pre-pyrolysis treatment, or any combination thereof.

11. The method of claim 9, wherein applying the shearing force heats the MPMW to temperatures ranging from about 100 degrees Celsius (°C) to about 350 °C to at least partially melt the MPMW.24CHEM0025-WO-ORD2512. The method of claim 9, wherein applying the shearing force comprises activating a motor mechanically connected to at least one shearing element to apply the shearing force to heat the MPMW via friction.

13. The method of claim 9, wherein the pre-pyrolysis treatment includes mixing the MPMW with water before, during, and / or after heating the MPMW, wherein the water enhances the sterilization of the MPMW, the heteroatom removal from the MPMW, or both, during the pre-pyrolysis treatment of the MPMW, and wherein the water is in liquid form, gaseous form, or a combination of liquid and gaseous form.

14. The method of claim 9, wherein the pre-pyrolysis treatment includes mixing the MPMW with a purge gas before, during, and / or after heating the MPMW, wherein the purge gas enhances the heteroatom removal from the MPMW.

15. The method of claim 9, wherein the pre-pyrolysis treatment includes directing an exhaust gas stream produced from heating the MPMW to an exhaust gas scrubber capable of removing at least one exhaust gas from the exhaust gas stream, and wherein the at least one exhaust gas comprises one of hydrogen chloride, hydrogen cyanide, acetic acid, ammonia, carbon monoxide, or carbon dioxide.

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