Process for depolymerizing plastic waste material using pyrolysis oil distillation and condensation

Abstract

A thermal catalytic process for depolymerization of waste plastic materials is disclosed. The process includes processing in two depolymerization reactors, a distillation unit, and a condensing device. The process has high efficiency and versatility and is capable of producing pyrolysis products in the form of oils for various end uses.

Description

Technical Field

[0001] This invention relates to the field of depolymerizing waste plastic materials into novel products comprising hydrocarbon oils, which possess valuable and useful properties. In one aspect, this invention relates to a process for converting plastics into liquid hydrocarbons, particularly liquid hydrocarbons used as hydrocarbon feedstocks. Background Technology

[0002] The awareness that waste plastics have a negative impact on the environment and therefore on the health of all forms of life is rapidly increasing.

[0003] One attempt to mitigate the impact is to recycle plastic materials from household and industrial users, allowing a portion of these plastics to re-enter the production cycle. This would involve positive outcomes such as less use of fossil hydrocarbon sources in the production of plastic items.

[0004] However, various factors indicate that this approach alone is insufficient. In fact, the mechanical recycling of plastic materials produces lower quality materials, is relatively costly and cumbersome, and is not suitable for certain urban wastes that are mixed with various other materials.

[0005] Therefore, most plastic waste is either used as thermal energy in equipment such as incinerators or simply stored in landfills, which, as mentioned, contribute to the degradation of the Earth's environment by increasing CO2 emissions and releasing harmful chemicals.

[0006] In light of the above, many attempts have been made in the past to efficiently reprocess waste plastics into liquid hydrocarbon products, which have valuable and useful properties, especially as fuel.

[0007] Thermal decomposition is a fundamental process in which plastic waste is converted into liquid fuels through thermal degradation (cracking) in the absence of oxygen. Plastic waste is typically first melted in a stainless steel chamber under an inert purge gas, such as nitrogen. The chamber then heats the molten material to a gaseous state, draws it into a catalytic converter, and cracks it to form carbon chains of varying lengths.

[0008] The pyrolysis gases, then heated within the desired carbon length range, are condensed in one or more condensers to produce a hydrocarbon distillate comprising straight-chain and branched aliphatic, cyclic aliphatic, and aromatic hydrocarbons. Depending on the composition, the resulting mixture is used in various applications, but in all cases, product consistency and quality requirements must always be met. Furthermore, given the unstable composition of waste plastic raw materials, achieving consistent quality in the recycled oil is challenging.

[0009] The temperature difference between the condenser and the subsequent depolymerization reactor is large, requiring a large amount of energy to be injected into the reactor to reach the depolymerization reaction conditions, making the whole process more energy-intensive.

[0010] In view of the foregoing, the object of this disclosure is to provide a process that provides high-quality depolymerization products in gaseous and liquid forms with lower energy consumption. Summary of the Invention

[0011] Therefore, this disclosure relates to a process for depolymerizing waste plastic materials.

[0012] In one aspect of this disclosure, the gaseous effluent from the first depolymerization reactor is directed to a distillation unit, from which a gaseous stream and a liquid stream are generated. The gaseous stream is then directed to a condensation unit to produce pyrolysis oil and pyrolysis gas. The liquid stream from the distillation unit is directed to a second depolymerization reactor, which has a temperature close to the depolymerization reaction temperature, thus requiring almost no additional energy to operate the second depolymerization reactor. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the depolymerization process equipment. Detailed Implementation

[0014] The process disclosed herein for depolymerizing waste plastic materials and producing pyrolysis products includes the following steps:

[0015] (a) In an anaerobic atmosphere, a mixture comprising waste plastic material is fed into a feeding system comprising at least one screw extruder (1), which is heated at the melting temperature of the plastic material;

[0016] (b) Molten plastic material from the extruder is fed into a first depolymerization reactor (2), which is operated at a temperature ranging from 280 to 600°C and a pressure ranging from 1 to 10 barg, so that depolymerization occurs, thereby forming gaseous effluent and liquid effluent.

[0017] (c) At least a portion of the liquid effluent generated in the first depolymerization reactor (2) is directed to the carbon treatment section (6), and the gaseous effluent from the reactor (2) is fed to the distillation unit (3) from which gaseous and liquid streams are generated, the distillation unit (3) comprising two or more equilibrium stages and operated with a distillation column having a bottom temperature ranging from 250 to 420°C;

[0018] (d) The gaseous flow from the distillation unit (3) is directed to a condensation unit (5) operating at a temperature lower than that of the distillation unit (3), and the liquid flow from the distillation unit (3) is directed to a second depolymerization reactor (4) having a temperature equal to or greater than 200°C. The second depolymerization reactor (4) is maintained at a temperature ranging from 280 to 600°C and operated at a pressure ranging from 1 to 10 barg, so that depolymerization occurs, thereby forming a gaseous effluent and a liquid effluent.

[0019] (e) Discharging the gaseous effluent from the second depolymerization reactor (4) and feeding the gaseous effluent into the distillation unit (3) and / or the condensation unit (5), and recycling at least a portion of the liquid effluent from the second depolymerization reactor (4) back to the first depolymerization reactor (2); and

[0020] (f) Recover pyrolysis oily products from the condensation unit (5).

[0021] Preferably, the process is carried out in a continuous mode.

[0022] In stage (a), the feeding system allows the waste plastic material to be fed into the reactor (2) preferably in a continuous mode. Care should be taken to avoid introducing an oxygen-containing atmosphere into the system. Barriers to potentially oxygen-containing atmospheres can be achieved through a range of measures, such as nitrogen covering and a vacuum system connected to the extruder barrel.

[0023] More specifically, the plastic waste mixture is fed into the feed system of the depolymerization reactor (2) through a hopper or two or more parallel hoppers, and the oxygen present in the atmosphere of the plastic waste material is substantially eliminated inside the hopper.

[0024] The process disclosed herein is highly flexible and can preferably be fed a wide range of plastic waste compositions, in which polyolefins are the most abundant component. This will increase the yield of high-value depolymerization products. In particular, when the pyrolysis products are to be recycled back to the cracking / refining unit, it is preferred to depolymerize a mixture of plastic waste in which the polyolefin (PE and PP) content is equal to or greater than 70% by weight.

[0025] The waste plastic materials preferably undergo a pretreatment stage in which they are melted by heating and possibly mixed with additives, which may be alkaline materials. This melt pretreatment transforms a heterogeneous mixture of different types of waste plastics into a large quantity of homogeneous plastic composites. Therefore, this pretreatment is also preferred for cases where primary pyrolysis is carried out without additives.

[0026] The heating temperature in the pretreatment stage is appropriately set according to the type and content of plastics contained in the waste plastic material, thereby inhibiting the pyrolytic decomposition of the plastic material to be treated. Such temperatures are typically in the range of 100°C to 300°C, preferably 150°C to 250°C. At temperatures close to 300°C or higher, any HCl present in the PVC resin will be eliminated.

[0027] If waste plastic materials are mixed with alkaline materials during the melt / knead pretreatment process, the resulting HCl gas can be removed and continuously neutralized or captured via the exhaust system. For the melt operation, a conventional kneader, an extruder with a screw, or similar equipment can be used. The plastic waste is preferably fed into the depolymerization reactor via an extruder.

[0028] The extruder melts the plastic waste to a high temperature (250 to 350°C) and injects it into the first depolymerization reactor (2). The extruder receives the plastic waste cut into small pieces into the feed hopper, conveys the flow in the melting zone, and heats the polymer through a combination of mixed energy and heat supplied by the barrel heater.

[0029] Additives can be optionally incorporated into the melt to reduce the corrosiveness of plastic waste or to improve the conversion process in the reaction zone.

[0030] During extrusion, one or more degassing steps can be anticipated to remove residual moisture present in the product.

[0031] Before being fed into reactor (2), the melt stream can be filtered to remove solid impurities present in the plastic waste.

[0032] It can be applied to any extrusion system, such as a single-screw extruder, a twin-screw extruder, a twin-screw extruder with a gear pump, or a combination thereof.

[0033] In a preferred embodiment, at least one of the depolymerization reactors (2) and (4) is operated in the presence of a depolymerization catalyst. Advantageously, this reduces the required reaction temperature and / or increases the reaction yield.

[0034] The depolymerization reactor (2) and / or the depolymerization reactor (4) can be continuous stirred tank reactors. Preferably, both the depolymerization reactor (2) and the depolymerization reactor (4) are continuous stirred tank reactors.

[0035] In a preferred embodiment, the depolymerization reactor (2) is a stirred vessel operated at a temperature ranging from 300 to 550°C, and preferably from 350 to 500°C, and at a pressure maintained in the range of 2.0 to 8 barg, preferably from 2.5 to 7 barg. These reaction conditions have been found to make the process more efficient.

[0036] In an attempt to improve the flowability of the material, a preferred embodiment is proposed in which the molten waste plastic material entering the reactor is premixed with hydrocarbon oil in a dedicated container.

[0037] The depolymerization reactor (2) preferably has a cylindrical section, which preferably has a circular bottom.

[0038] Preferably, it has a mixer mounted on the vertical axis of the reactor, the mixer being equipped with a geared motor that allows the mixer blades to rotate, thereby maintaining the system in a stirred state. The design of the mixer and the power of the motor can vary in terms of the reactor contents, volume, and shape; however, as a non-limiting example, a power of 0.2 to 2 kW / m³ is preferred. 3 More preferably 0.3 to 1.5 kW / m 3 The power input range for operating the reactor.

[0039] In a particular and preferred embodiment, a portion of the liquid slurry discharged from the bottom of the reactor (2) is optionally recirculated back to the top of the reactor via an external heater (8) through a recirculation pump (7).

[0040] Preferably, the reactor is heated via heat transfer guided by a stream of molten salt, which is heated to a temperature ranging from 300°C to 570°C and circulated within the reactor jacket and / or the external heaters mentioned above. This allows heat to be transferred and distributed to the reactor without heating the reactor itself via a furnace.

[0041] The feed circuit (not shown) from the molten salt to the reactor jacket is constructed to prevent leakage of the molten salt. The molten salt is molten solar salt, preferably composed of a mixture of sodium nitrate and potassium nitrate, and even more preferably in a weight ratio ranging from 2:3 to 3:2. The solar salt then receives heat from a dedicated furnace, which may be electric or fueled. In the latter case, a portion of the recovered oil from the condensation unit (5) may be used as feed to the furnace. In alternatives or combinations, heat may be generated by the combustion of gaseous or liquid hydrocarbons. Gaseous hydrocarbons are preferred.

[0042] Specifically, during operation, salt is propelled from the circulating pump into the jacket and / or heat exchanger. A series of fins ensures uniform distribution of the molten salt flow and maximizes the heat exchange coefficient.

[0043] The depolymerization process occurring within the reactor produces molecules with shortened chain lengths and low boiling points. This continuously operating chain-breaking mechanism, particularly near the reactor wall, produces increasingly smaller portions of gaseous molecules under operating temperatures and pressures.

[0044] As a result, the composition within the reactor covers a wide range of hydrocarbons, from methane to heavier products, saturated and olefinic, with straight-chain or highly branched structures. Some aromatic products and fused-ring structures may also be present.

[0045] Those that remain liquid under operating conditions help reduce the mass viscosity of the liquid. As a result of the depolymerization process and the feed composition, the contents of reactor (2) can be defined as the coexistence of a liquid slurry phase and a gas phase, in which solids, especially carbonaceous and inorganic substances, are dispersed in a liquid hydrocarbon mixture.

[0046] At least a portion of the liquid slurry phase is discharged from the bottom of the reactor and constitutes the liquid effluent sent to the carbon treatment section (6) (which is not in Figure 1 (As shown in the image).

[0047] From an operational perspective, it is preferable to trigger the discharge of the slurry phase from the bottom of the reactor by detecting that the density of the liquid slurry has reached a predetermined value using a density sensor.

[0048] As already mentioned, in a particular and preferred embodiment, a portion of the liquid slurry discharged from the bottom of the reactor (2) is optionally recirculated back to the top of the reactor via a recirculation pump (7) and an external heater (8).

[0049] According to a preferred embodiment, the liquid slurry portion recirculated to the reactor is discharged from a point on the reactor that is different from the discharge point of the liquid slurry portion sent to the carbon treatment.

[0050] According to another preferred embodiment, the liquid slurry portion recirculated to the reactor and the liquid slurry portion sent to the carbon treatment are both discharged from the same point and then separated sequentially.

[0051] The separation between the liquid slurry portion directed to the carbon treatment and the portion recirculated to the reactor can be performed before or after the circulation pump (7). In the latter embodiment, the liquid slurry is first fed into a dedicated container equipped with lower and upper outlet points. The liquid portion directed to the carbon treatment (6) is discharged from the lower outlet point in concentrated form, while the liquid portion to be recirculated to the reactor (2) is discharged from the upper outlet point.

[0052] The gaseous phase of reactor (2) constitutes a gaseous effluent, which is sent to distillation unit (3) for further processing.

[0053] The gaseous effluent comprises a mixture of light hydrocarbons, which may also contain some heavy hydrocarbons and entrained carbon particles. Preferably, the gaseous effluent is conveyed from the top of the reactor to the distillation unit (3).

[0054] The distillation unit (3) is preferably designed in such a way that the scrubbing zone and the distillation zone, preferably located in the same column, are combined.

[0055] In a preferred design, the lower part of the tower is a scrubber zone in which a liquid flow (preferably recirculated from the bottom of the tower) flows countercurrently downward with a gaseous effluent from reactor (2) and preferably reactor (4), which is fed into the lower part of the tower and guided upward.

[0056] The distillation zone is preferably located in the upper part of the column, in which a thermal gradient is established between the cold liquid flow from the condensation unit (5) and the hot gaseous effluent from the scrubber zone.

[0057] In a preferred embodiment, distillation is based on the use of packing material, and is therefore a packed distillation column.

[0058] Preferably, the distillation unit (3) has three or more equilibrium stages, preferably four or more equilibrium stages, and especially five to 20 equilibrium stages. Increasing the number of equilibrium stages improves the separation of components according to their respective boiling points.

[0059] In a preferred embodiment, the liquid stream collected at the bottom of the distillation unit (3) and fed to the second depolymerization reactor (4) has a temperature greater than 250°C, preferably greater than 300°C, more preferably 330°C to 450°C, and especially in the range of 350 to 400°C, as measured at the bottom of the distillation unit (3). This temperature is close to the reaction temperature in the second depolymerization reactor (4), which allows for energy savings in the process.

[0060] Although the properties of the oil collected at the bottom of the distillation unit (3) may vary depending on the specific feedstock and depolymerization conditions, in a particular and preferred embodiment, the average molecular weight (Mw) of the liquid stream from the distillation unit (3) is greater than 220 g / mol, preferably greater than 250 g / mol, more preferably greater than 280 g / mol, and especially greater than 300 g / mol. This will advantageously allow molecules that are primarily of high molecular weight to undergo a further depolymerization stage.

[0061] In another preferred embodiment, the pump (9) recirculates the liquid collected at the bottom of the tower to the top of the scrubber section of the tower. The recirculated liquid is cooled in a dedicated heat exchanger (10) before being injected as reflux into the top of the tower.

[0062] The gaseous stream (H2 and light hydrocarbons) from the distillation unit (3) is conveyed to the condensation unit (5) from which the oil is recovered.

[0063] As mentioned, at least a portion of the liquid condensate from the distillation unit (3) is transferred to the second depolymerization reactor (4) via a pump (11).

[0064] Preferably, the second depolymerization reactor (4) operates at a temperature ranging from 280 to 600°C and at a pressure higher than that of the first reactor, and particularly at a pressure ranging from 2 to 10 barg, preferably 3 to 9 barg, and more preferably 3 to 8 barg. This complements the reaction conditions of the first depolymerization reactor (2), thereby improving the overall output of the process.

[0065] In a preferred embodiment, the setup and operating conditions of the second reactor are the same as those of the first reactor.

[0066] Preferably, the gaseous effluent generated in reactor (4) is sent to distillation column (3), and more preferably it is combined with the gaseous effluent from reactor (2).

[0067] In an alternative implementation, the gaseous effluent is sent to a condensation unit (5).

[0068] The liquid effluent from reactor (4) is preferably a highly concentrated hydrocarbon slurry. It is discharged from the second reactor and returned to the first reactor via conduit (16). The same density control used in reactor (4) for discharging the slurry is also preferably applied to reactor (2).

[0069] Also in reactor (4), which is configured in a preferred embodiment, a portion of the liquid slurry discharged from the bottom of reactor (4) is recirculated back to the top of reactor by a recirculation pump (12) through an external heater (13).

[0070] Because the feed to reactor (4) includes condensate from reactor (2), it contains fewer impurities and produces less carbon. Preferably, fresh catalyst is fed into reactor (4).

[0071] According to this disclosure, the catalyst can be selected from those catalysts that are active as depolymerization / cracking catalysts in thermocatalytic processes. In particular, it can be selected from aluminosilicate catalysts, and preferably from zeolites. Among them, particularly preferred zeolites are synthetic Y-type zeolites and ZSM-5.

[0072] In a particularly preferred embodiment, the amount of catalyst feed is no more than 10% by weight, preferably no more than 5% by weight, and especially no more than 2% by weight relative to the plastic waste feed.

[0073] In a preferred embodiment, the catalyst is injected as a powder dispersed in a hydrocarbon oil, which is preferably a liquid pyrolysis product (oil) obtained from a distillation unit (3) and / or a condensation unit (5). In a preferred embodiment, the pyrolysis oil from which the catalyst is dispersed is preferably discharged from the condensation unit (5).

[0074] Preferably, the catalyst slurry is prepared in a tank-type continuous stirring vessel, wherein the catalyst is poured from a dedicated silo.

[0075] Once prepared, the catalyst slurry can be injected, preferably into the second reactor, via a screw pump, to maintain its level constant.

[0076] The gaseous effluent from the distillation unit (3) is transported to the condensation unit (5) to recover the pyrolysis products in the form of oil.

[0077] Preferably, the condensation unit (5) operates at a temperature ranging from 35 to 100°C, more preferably from 40 to 80°C.

[0078] The pressure value of the condensation unit (5) should preferably be lower than that of the distillation unit (3) so that non-condensable gases from the unit (3) can enter the unit (5) without further pressurization.

[0079] Preferably, the lower portion of the condensation unit (5) is designed as a scrubbing tower to suppress entrained solid particles. Furthermore, in this case, a portion of the liquid flow used for scrubbing is preferably recirculated from the bottom of the tower.

[0080] In a preferred configuration of the condensation unit (5), a partial condenser is installed at the top of the tower and operates at a temperature lower than the internal temperature of the tower. The condensate flows downwards by gravity as a return flow to the scrubber.

[0081] Condensers can be installed as standalone components or integrated inside the tower.

[0082] As previously mentioned, the pyrolysis product recovered from the condensation unit (5) in the form of oil is the final product of the depolymerization process of this disclosure.

[0083] In a preferred embodiment, a portion of the oil recovered from the condensation unit (5) is fed to the top of the condensation unit (3). Thus, the cold oil flow from the condensation unit (5) can be used to cool and partially condense the hot vapors from one or more pyrolysis reactors in the pyrolysis reactor.

[0084] The setup of this disclosure allows for the production of high-quality final pyrolysis oil, and in some cases, improved pyrolysis products compared to those obtained without the distillation unit (3). The quality improvement can be seen in the values ​​of various parameters such as final boiling point, compositional fractionation and distribution, and the low amount of high molecular weight and high boiling point fractions.

[0085] In one specific implementation, the average Mw of the pyrolysis products recovered from the condensation unit (5) in the form of oil is equal to or less than 165 g / mol, preferably less than 163 g / mol, more preferably less than 161 g / mol, and especially less than 160 g / mol.

[0086] In another preferred embodiment, the pyrolysis product recovered from the condensation unit (5) in oil form has the following composition (GC determination):

[0087] - Fractions of approximately 10% to 15% by weight having retention times equal to or less than that of n-heptane;

[0088] - A fraction of approximately 70% to 75% by weight with retention times consisting of n-heptane and n-dodecane, and

[0089] - Approximately 12% to 20% by weight of the product having a retention time higher than that of n-dodecane and lower than that of n-octacosane.

[0090] Preferably, the pyrolysis products recovered from the second condensation unit in oil form are used as hydrocarbon feedstock in the cracking unit.

[0091] Example

[0092] The following experiments are based on thermodynamic simulations of a depolymerization process performed in a device consisting of two reactors connected in series. Each device includes two pyrolysis reactors and two pyrolysis oil scrubbers, which are either two condensation units (comparison), or a distillation unit and a condensation unit.

[0093] The first pyrolysis oil scrubber (distillation unit) receives vapor from the first pyrolysis reactor and may also receive vapor from the second pyrolysis reactor (Example 2). Here, the hot vapor is cleaned by being pumped back to the final solid particles of the tower and cooled and partially condensed by a cold stream from the bottom of the second pyrolysis oil scrubber (condensation unit).

[0094] The cold stream from the bottom of the second pyrolysis oil scrubber is fed at the top of the distillation column, and its flow rate is determined by the desired quality of the final pyrolysis oil.

[0095] This section operates at approximately 1.5 barg.

[0096] The lighter fraction from the top of the tower is delivered to the second pyrolysis oil scrubber (condenser unit).

[0097] The heavier fraction from the bottom of the tower is fed into the second pyrolysis reactor for further cracking via the first-stage pyrolysis oil pump.

[0098] The second pyrolysis oil scrubber receives steam from the first pyrolysis oil scrubber and can also receive steam from the second pyrolysis reactor; here, part of the steam is condensed by a top condenser and cooled by jacket water.

[0099] The condensation temperature is approximately 50°C to maximize pyrolysis oil production. This section operates at approximately 1 barg.

[0100] Reference Case:

[0101] Steam from the top of the first reactor is fed into the condensation unit.

[0102] Example 1

[0103] Steam from the top of the first reactor is fed into the distillation unit.

[0104] Example 2

[0105] Steam from the tops of reactors 1 and 2 is fed into the distillation unit.

[0106]

[0107] (*) The calculation of load savings is to divide the difference between the total load in the specific embodiment and the total load in the reference case by the total load in the reference case, and then multiply by 100.

[0108] Select the optimal amount of reflux flow from the condenser to the distillation unit to ensure a good balance between load savings and the final pyrolysis oil quality.

[0109] Compared to the reference case, Example 1 shows an increased pyrolysis oil yield, as well as savings in both reactor load and condensation load. In Example 2, both steam from the top of the first reactor and steam from the top of the second reactor are fed to a distillation column. Compared to Example 1, in addition to a slight increase in yield, load savings are also achieved. Furthermore, compared to the reference case, both Examples (1 and 2) show a lighter final pyrolysis oil (the lower the Mw, the lighter the pyrolysis oil).

Claims

1. A process for depolymerizing waste plastic materials and producing pyrolysis products, wherein the process includes the following steps: (a) In an anaerobic atmosphere, a mixture comprising waste plastic material is fed into a feeding system comprising at least one screw extruder (1), the screw extruder being heated at the melting temperature of the plastic material; (b) Molten plastic material from the extruder is fed into a first depolymerization reactor (2), which is operated at a temperature ranging from 280 to 600°C and a pressure ranging from 1 to 10 barg, so that depolymerization occurs, thereby forming a gaseous effluent and a liquid effluent. (c) At least a portion of the liquid effluent generated in the first depolymerization reactor (2) is directed to the carbon treatment section (6), and the gaseous effluent from the reactor (2) is fed to a distillation unit (3) from which gaseous and liquid streams are generated, the distillation unit (3) comprising two or more equilibrium stages and operated with a distillation column having a bottom temperature ranging from 250 to 420°C; (d) The gaseous flow from the distillation unit (3) is directed to a condensation unit (5) operating at a temperature lower than that of the distillation unit (3), and the liquid flow from the distillation unit (3) is directed to a second depolymerization reactor (4) having a temperature equal to or greater than 200°C. The second depolymerization reactor (4) is maintained at a temperature ranging from 280 to 600°C and operated at a pressure ranging from 1 to 10 barg, causing depolymerization to occur, thereby forming a gaseous effluent and a liquid effluent. (e) Discharging the gaseous effluent from the second depolymerization reactor (4) and feeding the gaseous effluent into the distillation unit (3) and / or the condensation unit (5), and recycling at least a portion of the liquid effluent from the second depolymerization reactor (4) back to the first depolymerization reactor (2); and (f) Recover the pyrolysis products from the condensation unit (5).

2. The process according to claim 1, wherein the distillation unit (3) comprises three or more balancing stages, preferably five or more balancing stages, especially 10 balancing stages.

3. The process according to any one of claims 1 or 2, wherein the liquid stream collected at the bottom of the distillation unit (3) and fed to the second depolymerization reactor (4) has a temperature greater than 250°C, preferably greater than 300°C, more preferably 330°C to 450°C, especially in the range of 350 to 400°C, as measured at the bottom of the distillation unit (3).

4. The process according to one or more of the preceding claims, wherein the distillation unit (3) is designed in such a way that the scrubber area and the distillation area located in the same column are combined.

5. The process according to any one of the preceding claims, wherein a portion of the oil recovered from the condensation unit (5) is fed to the top of the distillation unit (3).

6. The process according to claims 4 and 5, wherein the lower portion of the tower is a scrubber zone in which the liquid flow flows countercurrently downward with the gaseous effluent from reactors (2) and (4), and the upper portion of the tower includes the distillation zone in which a thermal gradient is established between the cold liquid flow from the condensation unit (5) and the hot gaseous effluent from the scrubber zone.

7. The process according to any one of the preceding claims, wherein the condensation unit (5) operates at a temperature ranging from 35 to 100°C.

8. The process according to any one of the preceding claims, wherein the plastic waste is a mixture of waste materials, in which polyolefins are the most abundant component.

9. The process according to any one of the preceding claims, wherein at least one of the depolymerization reactor (2) and the depolymerization reactor (4) is operated in the presence of a depolymerization catalyst.

10. The process according to any one of the preceding claims, wherein the depolymerization reactor (2) and / or the depolymerization reactor (4) is a continuous stirred tank reactor.

11. The process according to any one of the preceding claims, wherein the depolymerization reactor (2) and the depolymerization reactor (4) are stirred vessels operating at a temperature ranging from 300 to 550°C, and more preferably from 350 to 500°C, and at a pressure maintained in the range of 2.0 to 8 barg, and more preferably from 2.5 to 7 barg.

12. The process according to any one of the preceding claims, wherein the gaseous effluent generated in the reactor (4) is fed to the distillation column (3), more preferably combined with the gaseous effluent from the reactor (2).

13. The process according to any one of the preceding claims, wherein a portion of the liquid slurry discharged from the bottom of the reactor (2) and the reactor (4) is optionally recirculated back to the reactor via an external heater (8) via a recirculation pump (7).

14. The process according to any one of the preceding claims, wherein the heating of the reactor is carried out by heat transfer guided by a molten salt stream, the molten salt stream being heated to a temperature ranging from 300°C to 570°C and circulating within the reactor jacket and / or the external heater.

15. The process according to any one of the preceding claims, wherein the average Mw of the pyrolysis product recovered from the condensation unit (5) in oil form is equal to or less than 165 g / mol, preferably less than 163 g / mol, more preferably less than 161 g / mol, and especially less than 160 g / mol.

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