A mixture of hydrocarbon compounds with improved properties obtained from plastic waste

Abstract

The present invention relates to a hydrocarbon compound mixture that is transparent in a layer of 40 mm thick at 20°C and has a cloud point of 15°C or less according to a relevant standard test method for measuring cloud point, obtained by a method of converting plastic waste into a liquid hydrocarbon compound mixture. The present invention further relates to a method of converting plastic waste into such a liquid hydrocarbon compound mixture and to the use of said hydrocarbon compound mixture as a feedstock for a crude oil refining unit or a steam cracker in an oil refinery.

Description

Technology Field

[0001] The present invention relates to a hydrocarbon compound mixture having improved properties obtained through a method of converting plastic waste into a liquid hydrocarbon compound mixture. Background Technology

[0002] Over the past few decades, the production of plastic materials worldwide has increased dramatically. Plastic materials possess significant advantages, such as chemical and mechanical stability and low weight, and their properties can be adjusted during the production process to meet the demands of various applications. However, most used plastic materials are currently sent for incineration or landfill, or even end up in nature. Today, plastic materials are generally made from fossil fuels, and a significant portion of the plastic produced is still designed for single-use. According to the European Commission (published on its website in 2023), nearly 26 million tons of plastic waste are generated annually in Europe, and the Commission is addressing the negative impacts of this plastic waste generation through various policies.

[0003] There have been various attempts to establish circular processes for reusing plastic materials through recycling and for reusing plastic materials as raw materials for new plastic materials. One approach to such circular processes is to convert waste plastic materials into mixtures of oily hydrocarbon compounds that can be used as alternative feedstocks in oil refinery crude units or steam crackers through thermal decomposition or pyrolysis. For this reuse, the mixtures of hydrocarbon compounds must meet specific quality requirements, and these requirements become more critical as the percentage of the feed volume of these mixtures in the oil refinery crude units or steam crackers increases.

[0004] Several methods for converting waste plastic materials into petroleum products through pyrolysis or pyrolysis are already known.

[0005] US20160024390A1 discloses a two-stage pyrolithesis apparatus for continuously converting a hydrocarbon material into a condensable, non-condensable, and solid hydrocarbon material. The apparatus comprises at least one extruder capable of providing shear force and heat and having three or more processing zones, a continuous process heat kiln reactor (wherein the extruder and the kiln reactor are in fluid communication), and means for transporting the hydrocarbon material through the apparatus. The hydrocarbon material is maintained within the zones for a defined range of temperature and residence time, wherein the extruder has at least three zones and the kiln reactor has at least two zones. During the process, the wax is removed from the reactor as a solid material.

[0006] WO2019202546A1 discloses a pyrology apparatus for the thermal depolymerization of plastic materials. The apparatus comprises a closed vessel for a reactor connected to a feeder for supplying plastic materials, and the reactor vessel has an outlet for gaseous products generated from depolymerization, a mechanical mixer, and an outlet for removing unevaporated heavy fractions.

[0007] WO2022013712A1 discloses a method for pyrolilysis of waste. The method comprises the steps of providing a screw device configured to supply heat to a material by mechanical shearing; providing a reactor configured to supply heat to a material (mass) in the absence of oxygen by heating the reactor wall behind the screw device; heating the material within the screw device to an outlet temperature and increasing the pressure to an outlet pressure; and pyrolyzing the material within the reactor, wherein the material reaches an extreme state at the outlet temperature and outlet pressure by the screw device, and pyrolilysis occurs during the pressure drop, and gaseous hydrocarbons are formed within the connecting element.

[0008] US20210189252A1 and US20210189254A1 disclose a circular economy approach for the recycling of polyethylene and polypropylene waste plastics through a refining process. Typical pyrolilysis oils were obtained from commercial sources, and their characteristics are summarized. These pyrolilysis samples were prepared from waste plastics, generally containing polyethylene and polypropylene, by pyrolysis in a pyrolilysis reactor at approximately 400 to 600°C, and the final boiling point for 99.5% of these samples is 888°F to 1079°F, corresponding to approximately 475°C to 581°C.

[0009] The aforementioned publications do not mention the quality of the pyrolisis oil produced from the disclosed method, or describe the characteristics of the pyrolisis oil as having a significant amount of fractions with a high boiling point of 450°C or higher. A significant amount of these high boiling point fractions indicates that the pyrolisis reaction was insufficient and contains a large amount of hydrocarbon compounds with long carbon chains such as wax.

[0010] The object of the present invention is to provide a mixture of hydrocarbon compounds obtained from plastic waste that has improved characteristics and can be used in large quantities to replace fossil feedstocks in oil refineries and steam cracker processes.

[0011] Another objective of the present invention is to provide a method step for converting plastic waste into a hydrocarbon compound material, which can yield a hydrocarbon compound material having improved properties.

[0012] Accordingly, the inventors have discovered a mixture of hydrocarbon compounds having improved properties obtained from plastic waste and a process step for obtaining such an improved mixture of hydrocarbon compounds. Specific details for implementing the invention

[0013] In the first aspect of the present invention, the inventors discovered a transparent hydrocarbon compound mixture in a layer 40 mm thick at 20°C, with a cloud point of 15°C or less according to a relevant standard test method for measuring cloud point, obtained by a method of converting plastic waste into a liquid hydrocarbon compound mixture.

[0014] More specifically, the inventors discovered a transparent hydrocarbon compound mixture obtained by a method of converting plastic waste into a liquid hydrocarbon compound mixture, having a cloud point of 15°C or less as measured according to ASTM D2500-23, and a layer of 40 mm thick at 20°C according to the ASTM D2500-23 standard test method for measuring the cloud point.

[0015] A high cloud point is an indicator of the presence of fractions with high molecular weight and / or long carbon chains, such as wax, within a hydrocarbon mixture, which tend to precipitate from the mixture. The precipitation of these fractions can cause contamination in production plant storage, transport and conveyor systems, transportation processes for subsequent processes, and refinery or steam cracker facilities, and it is desirable to minimize such contamination.

[0016] In a preferred embodiment of the present invention, the hydrocarbon compound mixture has a cloud point of 5°C or lower, much more preferably 5°C or lower, more preferably -15°C or lower, and even more preferably -25°C or lower.

[0017] In a further aspect of the present invention, the inventors have discovered a hydrocarbon compound mixture, wherein the hydrocarbon mixture has a final boiling point of 430°C or less, preferably 420°C or less, much more preferably 410°C or less, and even more preferably 400°C or less, for 99.5% by weight of the mixture.

[0018] In particular, the inventors have discovered a hydrocarbon compound mixture, the hydrocarbon mixture having a final boiling point (measured according to ASTM D2887-22) of 430°C or less, preferably 420°C or less, much more preferably 410°C or less, and even more preferably 400°C or less for 99.5% by weight of the mixture.

[0019] A hydrocarbon compound mixture according to the present invention can be obtained by applying a method comprising a predetermined process step.

[0020] According to a preferred embodiment of the present invention, a hydrocarbon compound mixture is obtained by a method comprising the following steps:

[0021] A) Step of melting and degassing plastic waste,

[0022] B) a step of pyrolicing molten plastic waste within a device, wherein the device comprises at least two different pyrolicing compartments in which pyrolicing vapor is generated, wherein the vapor in the first compartment among these compartments has a higher temperature than the vapor in the second compartment, and the at least two compartments are connected to each other so that the vapor formed in the first compartment moves to the second compartment and the liquid formed in the second compartment returns to the first compartment, said pyrolicing step

[0023] C) A step of obtaining a liquid hydrocarbon compound mixture by condensing the steam generated in the last of at least two compartments.

[0024] In addition to these process steps, it is advantageous to prepare plastic waste for the aforementioned process steps. Advantageously, the plastic waste is initially heated and compressed in a densification device. Due to the applied heat, unwanted gases and some of the water evaporate, and the viscosity of the plastic waste decreases, causing it to begin melting.

[0025] In process step A), the plastic waste is further heated until it is substantially melted. During this step, additional unwanted gases are evaporated. The optimal temperature applied in step A) depends on the type of plastic being processed and the type and amount of unwanted gases present in the plastic waste. In a preferred embodiment, this is applicable to a number of common plastic waste mixtures, and the final temperature of step A) is set to a range of 220 to 340°C, preferably 240 to 320°C. The temperature range mentioned above refers to the temperature at the end of this process step, that is, the temperature at which the material reaches the final temperature. When the material is introduced into the apparatus where step A) is performed, the material may have a lower temperature due to a previous preparation step, and the material is heated inside the apparatus where step A) is performed until it reaches a temperature set point. The material introduced into the apparatus where step A) is performed may have a temperature of, for example, 150 to 200°C.

[0026] During the melting and degassing stages, the viscosity of the mixture is further reduced, allowing the mixture to be more easily transported to the compartment where actual pyrolisis is performed. Furthermore, this prevents certain corrosive gases and / or air from entering the compartment where pyrolisis occurs.

[0027] In process step B), the molten plastic waste undergoes a controlled decomposition or pyrolisis reaction. According to the present invention, the pyrolisis reaction is carried out in a device having at least two different compartments. This means that the compartments are physically separated so that process conditions, particularly temperature, can be controlled accurately and independently in each compartment. The first compartment is generally set to a higher temperature than the second compartment. In this context, the first compartment refers to the compartment into which the material after step A) first enters. Due to the higher temperature compared to the temperature applied in process step A), the molten plastic material initiates a rapid pyrolisis reaction. Due to vapor pressure, the vapor generated in this pyrolisis reaction is continuously discharged from the first compartment to the second compartment through an interconnection device for further processing.

[0028] Because the temperature of the second compartment is lower than the temperature of the first compartment, some of the steam escaping from the first compartment condenses in the second compartment. As a result, an oil phase accumulates at the bottom of the second compartment. This oil phase is further pyrolised in the second compartment, which is controlled by an applied temperature setting. According to a preferred embodiment of the present invention, steam from the first compartment is introduced into the oil phase of the second compartment through a pipe submerged in the oil phase. Through this method, the steam is cooled more efficiently to the temperature of the second compartment, and a significant portion of the steam is prevented from escaping the second compartment without being further exposed to the pyrolised conditions of the second compartment.

[0029] The device in which the pyrolilysis phase occurs further comprises an interconnecting device between the second compartment and the first compartment that allows a liquid, such as an oil phase present in the second compartment, to move back into the first compartment. The backflow of the liquid is preferably carried out in a controlled manner, for example, by a valve within such interconnecting device, so that the oil level in the second compartment, the liquid level in the first compartment, and the residence time in both compartments can be controlled.

[0030] The process steps applied according to the present invention allow an operator to change various process parameters to precisely adjust the throughput through the device and the characteristics of the resulting hydrocarbon compound mixture. In particular, the feed rate to the first compartment, the temperatures of the first and second compartments, and the backflow of liquid material from the second compartment to the first compartment are important variables for producing the desired product quality.

[0031] According to a preferred embodiment of the present invention, the hydrocarbon compound mixture of the present invention is obtained by a process in which the steam temperature in the first compartment is set to a range of 400°C or higher and 500°C or lower, preferably 420°C or higher and 460°C or lower.

[0032] According to a preferred embodiment of the present invention, the hydrocarbon compound mixture of the present invention is obtained by a process in which the steam temperature in the second compartment is set to a range of 350°C or higher and 450°C or lower, preferably 370°C or higher and 400°C or lower.

[0033] Fine-tuning of these temperature settings depends on the composition of the plastic waste, the desired throughput through the device, and the backflow rate of the liquid from the second compartment to the first compartment, and a skilled operator can optimize these process variables by measuring the desired quality of the final hydrocarbon compound mixture based on small changes in process variables.

[0034] As can be seen from the description of the process steps mentioned above, it is evident that more decomposition occurs in the first compartment because the pyrolilysis reaction in the first compartment is performed under harsher conditions compared to the second compartment. This implies that the first compartment is generally set to residence time and temperature conditions that allow large volumes of plastic waste to be efficiently decomposed. Then, the residence time and temperature settings in the second compartment are adjusted for the fine-tuning of the pyrolilysis reaction, so that decomposition can reach the desired level and the quality of the final hydrocarbon compound mixture can be optimized.

[0035] According to a preferred embodiment of the present invention, the hydrocarbon compound mixture of the present invention is obtained by a process in which the steam temperature in the first compartment is at least 10°C higher than that in the second compartment, preferably at least 20°C higher, and much more preferably at least 30°C higher.

[0036] In addition to temperature, residence time is an important parameter for controlling the quality of the final hydrocarbon compound mixture. The residence time of the pyrrolides mixture in the first compartment is controlled particularly by the supply of raw materials to that compartment, the ratio of oil flowing back from the second compartment, and the temperature applied to the first compartment. While it is often desirable to obtain a sufficiently high degree of decomposition to obtain a homogeneous liquid hydrocarbon compound mixture, the degree of decomposition should not be too high, as additional cracking in a crude oil refining unit or steam cracker in a refinery can often be performed under energetically favorable conditions and, in particular, fine-tuned to obtain the desired end product of the refinery or steam cracker. The advantage of the apparatus and process steps as described in the present invention is that they provide the flexibility to obtain various high-quality hydrocarbon compound mixtures by varying the aforementioned process conditions, including the residence time within the compartment.

[0037] According to a preferred embodiment of the present invention, the hydrocarbon compound mixture of the present invention is obtained by a process in which the average residence time of the reaction mixture in the first compartment is 30 to 240 minutes, preferably 60 to 180 minutes, and much more preferably 90 to 150 minutes.

[0038] According to another preferred embodiment of the present invention, the hydrocarbon compound mixture of the present invention is obtained by a process in which the average residence time of the reaction mixture in the second compartment is 30 to 240 minutes, preferably 60 to 180 minutes, and much more preferably 90 to 150 minutes.

[0039] The average residence time mentioned above is a residence time that can be calculated based on the supply of liquid or molten plastic waste obtained from a previous process step to each first compartment or the next compartment, and the volume of liquid occupied within each corresponding compartment. In a continuous process under steady-state conditions, the residence time can be determined based on the supply amount and the volume of liquid occupied within the corresponding first compartment, without considering backflow from the second compartment to the first compartment.

[0040] The quality of the final hydrocarbon compound mixture can be further improved by using a device that includes an additional compartment where pyrrolides can occur. According to a preferred embodiment of the present invention, the hydrocarbon compound mixture of the present invention is obtained by a process in which the device includes three different compartments, the third compartment has a lower steam temperature than the second compartment, and the second and third compartments have one or more interconnecting devices that allow steam formed in the second compartment to move to the third compartment and liquid formed in the third compartment to return to the second compartment.

[0041] The options for controlling the process described in the section relating to the interconnection device between the first and second compartments are applied mutatis mutandis to the interconnection device between the third and second compartments. The third compartment enables further fine-tuning of the specifications and quality of the final product and allows for the production of a much more homogeneous mixture of hydrocarbon compounds having a desired cloud point and final boiling point. In a preferred embodiment of the present invention, the third compartment may be designed with one or more reflux condensers, whereby, depending on the temperature setting, some or all of the vapor exiting the second compartment is condensed and returned to the second compartment to continue the pyrolisis reaction, and thereafter, when the pyrolisis reaction proceeds to a certain stage, some of the vapor entering the one or more reflux condensers will no longer be condensed and will exit the reflux condenser(s) to proceed to the condensation stage C).

[0042] In principle, two or more sections can be arranged in various ways or geometrically, either horizontally or vertically, or even at a certain physical distance from each other. However, from an economic standpoint, it is advantageous to arrange the sections vertically close to each other.

[0043] According to a preferred embodiment of the present invention, a hydrocarbon compound mixture of the present invention is obtained by a process in which at least two compartments are arranged such that the first compartment is at the lowest position and the successive compartment(s) are positioned above each previous compartment.

[0044] In process step C), the steam passing through the cooling means of the last compartment is condensed to obtain a liquid hydrocarbon mixture. Cooling can be achieved by a standard cooling means, such as a cylindrical multi-tube heat exchanger.

[0045] According to a preferred embodiment of the present invention, the hydrocarbon compound mixture of the present invention is obtained by a process in which the outlet temperature of the device where condensation of step C) occurs is set to a value of less than 180°C.

[0046] If fractionation of the condensate is required, step C) may be arranged into a cascade condensation step. In this case, an additional condenser that cools to a different temperature may be used. The final outlet temperature of the condenser associated with process step C) is preferably set to an ambient temperature such as 20 to 30°C.

[0047] According to a preferred embodiment of the present invention, the hydrocarbon compound mixture of the present invention is obtained by a process in which the condensation of process step C) takes place in more than one condensation device and at least two of these condensation devices are operated at different temperatures.

[0048] From this description, it can be seen that the quality of the hydrocarbon compound mixture according to the present invention can be steadily adjusted and optimized by fine-tuning process conditions, such as the reaction temperature of different compartments, residence time, and the reflux ratio between different compartments. Such fine-tuning can be better achieved when the process proceeds continuously, and since the process described herein has this capability, it can produce a hydrocarbon compound mixture of better quality.

[0049] According to a preferred embodiment of the present invention, the hydrocarbon compound mixture of the present invention is obtained by a continuous process.

[0050] Since the pyrolisis reaction requires a continuous supply of thermal energy, a suitable energy source is important for the economical and efficient operation of the process described in the present invention. Generally, this energy can be provided in the form of fuel, for example, gas or oil burners. According to the present invention, it has been found that heating can be best achieved by an electric heating device. Such an electric heating device can be adjusted more precisely and quickly than fuel-based, particularly synthetic gas-based, heating devices, and has served as a significant advantage in fine-tuning the temperature settings of several compartments, particularly the first compartment where most of the pyrolisis reaction takes place and where the temperature cannot be further controlled through a reflux condenser.

[0051] According to a preferred embodiment of the present invention, the hydrocarbon compound mixture of the present invention is obtained by a process in which a first compartment is heated by an electric heater.

[0052] According to another preferred embodiment of the present invention, the hydrocarbon compound mixture of the present invention is obtained by a process in which a first compartment and a second compartment are heated by an electric heater.

[0053] Some processes for the pyrolithization of plastic waste known in the art attempt to reduce the amount of wax that may form during the pyrolithization process by separating the wax in the early stages of the process and recovering it as a solid product. However, in these processes, additional wax may be formed or not sufficiently removed during the later stages of the pyrolithization process. Consequently, these processes generally produce pyrolithization oil containing a significant amount of wax, and as a result, the final pyrolithization oil is not completely homogeneous, particularly at low temperatures. The hydrocarbon compound mixture according to the present invention is obtained by a process designed to decompose this material in a controlled manner so as not to separate the wax into a side stream, but to avoid any significant impact on the final hydrocarbon compound mixture. Furthermore, for the same reason, the yield of the final hydrocarbon compound mixture is higher than when the wax is removed in a solid state and no additional pyrolithization occurs in the process.

[0054] According to a preferred embodiment of the present invention, the hydrocarbon compound mixture of the present invention is obtained by a process that does not include the step of physically removing wax from any pyrorilysis compartment.

[0055] The plastic waste from which the hydrocarbon compound mixture of the present invention may be produced may be, for example, any plastic waste as defined by the United Nations Environment Programme (UNEP), namely any waste plastic (organic or synthetic material derived from polymers, resins, or cellulose) generated by any industrial process or by consumers. Waste plastic generated by industrial processes is typically well-defined and may contain fewer unwanted by-products. Waste plastic waste generated by consumers generally contains various plastic polymers of different compositions and also contains unwanted by-products such as food waste. Because plastic waste collection systems vary from country to country or even from community to community, the composition of the plastic waste subject to pyrolilysis may also vary. After plastic waste is collected, it is generally pretreated and separated from metals, paper, and other components. According to the present invention, any such commonly pretreated plastic waste may be processed into the hydrocarbon compound mixture of the present invention.

[0056] According to a preferred embodiment of the present invention, the hydrocarbon compound mixture of the present invention is obtained by a process in which the plastic waste is mixed plastic waste that is used and discarded by consumers.

[0057] The hydrocarbon compound mixture obtained according to the present invention may represent an element of the circular economy concept of recycling plastic polymers into new plastic polymers. According to this circular economy concept, plastic polymers are collected after use and converted into the hydrocarbon compound mixture of the present invention by applying the process steps described in this disclosure. The hydrocarbon compound mixture may then be fed to a crude oil refining unit of a refinery to be hydrotreated and further decomposed to produce, for example, a feedstock suitable for a steam cracker, or it may be fed directly to a steam cracker to produce new monomers and be processed into new plastic polymers.

[0058] Accordingly, an embodiment of the present invention uses a mixture of hydrocarbon compounds according to the present invention as a feedstock for a crude oil refining device or a steam cracker in a refinery.

[0059] In the following, an apparatus in which the process steps described in the present disclosure can be performed is described in more detail. The description of this apparatus is not intended to limit the general disclosure of the invention as set forth in this specification, but merely to illustrate a preferred manner in which the process steps described in the invention can be performed. FIG. 1 shows an example of such an apparatus.

[0060] Plastic waste is fed, for example, to a coagulator (101) via a conveyor belt. The coagulator compresses the plastic waste. Compression can be achieved by one or more screw conveyors containing the coagulator (101). Compression heats the residual polymer product due to frictional effects. Although at least a portion of the polymer product may melt due to heating, the heating is at a sufficiently low level so that substantial chemical decomposition does not occur. However, heating may generate some water vapor from the polymer product, which is desirable to remove. The coagulator may be configured to heat the residual polymer product to a temperature within the range of 150 to 200°C. The polymer product mixture, which is compressed, heated, and can be partially melted, is transferred, for example, to a degassing device (102) via a heated pipe, so that the partially melted polymer mixture will not solidify within the pipe.

[0061] The degassing device (102) includes a screw conveyor that moves the residual polymer product from the inlet to the degassing device outlet. The degassing device (102) includes a heater, such as an electric heater, for heating the polymer product to a final temperature in the range of 240 to 330°C. The preferred outlet temperature of the molten residual polymer product at the degassing device outlet may be a temperature in the range of 250 to 270°C, preferably 255 to 265°C. Heating in the degassing device (102) vaporizes substantially all moisture content and other unwanted volatile substances, as well as non-condensable gases. These unwanted volatile substances may include unwanted vapors such as corrosive gases and steam. The removal of these unwanted volatile substances enables the use of materials with low corrosion resistance in downstream components of the device, such as a pyrolysis reactor, thereby obtaining procedural as well as economic advantages.

[0062] To improve the quality of the hydrocarbon compound mixture produced in the device, calcium oxide or other alkaline substances may be supplied to the coagulator (101) or the degassing device (102). Adding such alkaline substances can neutralize acidic gases produced during the pyrolilysis of chlorine-containing polymers, particularly polyvinyl chloride.

[0063] In the device shown, the pyrolisis reactor (103), which is the first compartment of the process described in the present invention, is arranged at an angle so that the level of the liquid mixture inside the reactor does not reach the top end of the reactor. The pyrolisis reactor (103) includes two reactor screw conveyors for moving and mixing the liquid mixture and for transporting the solid residue, in particular carbon black, generated during the pyrolisis reaction toward the outlet. The pyrolisis reactor (103) is heated by a heater, such as an electric heater, to heat the reaction mixture to a temperature within the range of 400°C to 500°C to generate pyrolisis vapor. The temperature inside the pyrolisis reactor may vary depending on the liquid phase at the reactor inlet, the liquid phase at the top of the reactor, and the vapor phase. The temperature range mentioned above refers to the temperature of the vapor phase inside the reactor, and this applies to all embodiments of the present invention described herein. The vapor temperature inside the compartment may also not always be constant, because higher temperature vapor introduced from a previous compartment requires a certain amount of time to adapt to the new temperature setting applied to the successive compartment. In such cases, the steam temperature at the outlet of each compartment should be used to determine the temperature range described in this specification.

[0064] Upon heating, the reaction mixture gradually undergoes pyrrolization to form vapor containing hydrocarbon compounds, which exits the pyrrolization reactor and moves to the second compartment, in this case, an oil reactor where a liquid oil phase and a vapor phase exist.

[0065] The oil reactor (104) is a tank arranged to separate the pyrolisis vapor introduced from the pyrolisis reactor (103) into a vapor component and a liquid component. The oil reactor (104) may include a stirrer for mixing the contents. The pyrolisis vapor is introduced into the oil reactor (104) through a nozzle at the top and / or a dip pipe entering the liquid phase of the tank. The tank temperature can be controlled within a temperature range of 350°C to 450°C. For example, a temperature control system may be provided to control the tank temperature according to a desired temperature setpoint. The temperature within the oil reactor (104) may be controlled, for example, by an electric heater. Between the oil reactor (104) and the pyrolisis reactor (103), there is an interconnection device capable of controlling backflow from the oil reactor (104) to the pyrolisis reactor (103). In this way, a portion of the liquid in the oil reactor may be further exposed to the pyrolisis conditions of the pyrolisis reactor (103). Additionally, in the oil reactor, the temperature may differ between the oil phase and the vapor phase, and the temperature mentioned above refers to the temperature in the vapor phase.

[0066] In the illustrated configuration, the oil reactor (104) includes two separate outlets for transferring the steam generated in the oil reactor (104) to two reflux condensers (105a, 105b) through respective pipes. Through the same pipes, the liquid condensed in the reflux condensers (105a, 105b) will be returned to the oil reactor (104) through the liquid outlets of the reflux condensers. Thus, these liquid outlets also function as steam inlets. The reflux condensers (105a, 105b) are arranged to condense at least a portion of the steam component from the oil reactor (104) into a liquid component. The device is equipped with two reflux condensers that enable additional operation of the device even while one of the reflux condensers is stopped for cleaning or maintenance. The two reflux condensers may be configured as cylindrical multi-tube heat exchangers with pyrolysis steam on the tube side and thermal oil for temperature control on the shell side.

[0067] The steam exiting the reflux condensers (105a and 105b) travels through pipe connections to the condensers (106a and 106b), where the steam is condensed into liquid pyrolysis oil. In the illustrated configuration, the condensers are installed in duplicate so that one condenser can be maintained and cleaned while the device continues to operate. The condensers can be designed as standard cylindrical multi-tube heat exchangers. To separate the pyrolysis oil, the condensers (106a and 106b) can be set to a temperature range, for example, between 130 and 180°C, and the steam passing through the condensers in that temperature range can be further condensed in the condenser (107) set to a lower temperature to obtain a lighter fraction of the pyrolysis product, such as naphtha.

[0068] A further aspect of the present invention provides a method for converting plastic waste into a transparent liquid hydrocarbon compound mixture in a layer of 40 mm thick at 20°C, with a cloud point of 15°C or less according to a relevant standard test method for measuring the cloud point.

[0069] A specific embodiment of the present invention provides a method for converting plastic waste into a transparent liquid hydrocarbon compound mixture in a layer 40 mm thick at 20°C according to ASTM D2500-23, which is a standard test method for measuring cloud point, and a cloud point of 15°C or less when measured according to ASTM D2500-23.

[0070] According to a preferred embodiment, a method comprising the following steps has been discovered:

[0071] A) Step of melting and degassing plastic waste,

[0072] B) a step of pyrolicing molten plastic waste within a device, wherein the device comprises at least two different pyrolicing compartments in which pyrolicing vapor is generated, wherein the vapor in the first compartment among these compartments has a higher temperature than the vapor in the second compartment, and the at least two compartments are connected to each other so that the vapor formed in the first compartment moves to the second compartment and the liquid formed in the second compartment returns to the first compartment, said pyrolicing step

[0073] C) A step of obtaining a liquid hydrocarbon compound mixture by condensing the steam generated in the last of at least two compartments.

[0074] According to a preferred embodiment, the present invention

[0075] A method comprising converting plastic waste into a transparent liquid hydrocarbon compound mixture in a layer 40 mm thick at 20°C according to ASTM D2500-23, which is a standard test method for measuring cloud point, wherein the cloud point is 15°C or lower when measured according to ASTM D2500-23, said method comprises the following steps:

[0076] A) Step of melting and degassing plastic waste,

[0077] B) a step of pyrolicing molten plastic waste within a device, wherein the device comprises at least two different pyrolicing compartments in which pyrolicing vapor is generated, wherein the vapor in the first compartment among these compartments has a higher temperature than the vapor in the second compartment, and at least two compartments are connected to each other so that the vapor formed in the first compartment moves to the second compartment and the liquid formed in the second compartment returns to the first compartment, wherein the vapor temperature in the first compartment is set in the range of 400°C or higher and 500°C or lower, preferably 420°C or higher and 460°C or lower, and the vapor temperature in the second compartment is set in the range of 350°C or higher and 450°C or lower, preferably 370°C or higher and 400°C or lower.

[0078] C) A step of obtaining a liquid hydrocarbon compound mixture by condensing the steam generated in the last of at least two compartments. Some processes for the pyrolithization of plastic waste known in the art involve adding heated sand, molten salt, or other heat transfer media to the molten plastic waste to increase or control the temperature of the pyrolithization mixture or to facilitate heat distribution within the pyrolithization mixture. The addition of such heat transfer media has the disadvantage that additional process steps are required to separate these heat transfer media. The method according to the present invention does not require the addition of such heat transfer media, and a high-quality liquid hydrocarbon compound mixture can be obtained without adding such heat transfer media.

[0079] Accordingly, according to another preferred embodiment, the inventors have discovered a method for converting plastic waste into a transparent liquid hydrocarbon compound mixture in a layer of thickness of 40 mm at 20°C according to ASTM D2500-23, which is a standard test method for measuring cloud point, such that the cloud point is 15°C or less when measured according to ASTM D2500-23, and said method

[0080] A) Step of melting and degassing plastic waste,

[0081] B) a step of pyrolicing molten plastic waste within a device, wherein the device comprises at least two different pyrolicing compartments in which pyrolicing vapor is generated, wherein the vapor in the first compartment among these compartments has a higher temperature than the vapor in the second compartment, and the at least two compartments are connected to each other so that the vapor formed in the first compartment moves to the second compartment and the liquid formed in the second compartment returns to the first compartment, said pyrolicing step

[0082] C) A step of condensing the vapor generated in the last of at least two compartments to obtain a liquid hydrocarbon compound mixture

[0083] It includes, but heated sand, molten salt, or other heat transfer medium is not added to the pyrrollysis reaction.

[0084] According to another preferred embodiment, the process of the present invention, which is a continuous process, is found, and the hydrocarbon compound mixture is controlled by applying the following steps:

[0085] i) a step of adjusting the steam temperature in the first compartment to a range of 400℃ or higher and 500℃ or lower,

[0086] ii) a step of determining the quality of a hydrocarbon compound mixture obtained after process step C) by applying a method for measuring a quality parameter correlated with the amount of a high molecular weight compound having a boiling point of 410°C or higher in the hydrocarbon compound mixture,

[0087] iii) A step of gradually increasing or decreasing the steam temperature in the first compartment so that the quality parameter reaches a value corresponding to a predetermined quality parameter threshold.

[0088] Suitable methods for measuring quality parameters correlated with the amount of such high molecular weight compounds having a boiling point of 410°C or higher in a hydrocarbon compound mixture include, for example, the ASTM D2500-23 method for measuring cloud point or the ASTM 2887-22 method for measuring final boiling point; however, according to specific embodiments of the present invention, other methods capable of obtaining similar quality results may also be used. For example, if a cloud point measurement method such as ASTM D2500-23 is used and the transparency of the final hydrocarbon compound mixture does not meet the transparency requirements of that method, the vapor temperature in the first pyrorilysis compartment may first be increased or decreased until the transparency requirements are met, and then further adjusted until a desired quality parameter threshold is reached. This desired quality parameter threshold may be, for example, a cloud point of 15°C or lower, but other quality parameter thresholds corresponding to the quality specifications set by the manufacturer of the hydrocarbon compound mixture may also be used.

[0089] All preferred embodiments and practices described in this disclosure in relation to a mixture of hydrocarbon compounds and the process steps by which the mixture of hydrocarbon compounds is obtained are considered to be preferred embodiments and practices of the process of the present invention, either alone or in combination as specified in the claims of the present invention.

Claims

Claim 1 A hydrocarbon compound mixture having a cloud point of 15°C or less when measured according to ASTM D2500-23, and being transparent in a 40 mm thick layer at 20°C according to ASTM D2500-23, which is a standard test method for measuring cloud point, and a hydrocarbon compound mixture obtained by a process of converting plastic waste into a liquid hydrocarbon compound mixture. Claim 2 In claim 1, the hydrocarbon mixture is a hydrocarbon compound mixture having a final boiling point of 430°C or lower for 99.5% by weight of the mixture. Claim 3 A hydrocarbon compound mixture obtained by a process comprising, in claim 1 or 2, A) a step of melting and degassing the plastic waste; B) a step of pyrolyzing the melted plastic waste within a device, wherein the device comprises at least two different pyrrolysis compartments in which pyrrolysis vapor is generated, wherein the vapor in the first compartment among the compartments has a higher temperature than the vapor in the second compartment, and the at least two compartments are connected to each other so that the vapor formed in the first compartment moves to the second compartment and the liquid formed in the second compartment returns to the first compartment; and C) a step of condensing the vapor generated in the last compartment among the at least two compartments to obtain a liquid hydrocarbon compound mixture. Claim 4 A hydrocarbon compound mixture according to any one of claims 1 to 3, wherein the steam temperature in the first compartment is set to a range of 400°C or higher and 500°C or lower, preferably 420°C or higher and 460°C or lower. Claim 5 A hydrocarbon compound mixture according to any one of claims 1 to 4, wherein the steam temperature in the second compartment is set to a range of 350°C or higher and 450°C or lower, preferably 370°C or higher and 400°C or lower. Claim 6 A hydrocarbon compound mixture according to any one of claims 1 to 5, wherein the steam temperature in the first compartment is at least 10°C, preferably at least 20°C, and much more preferably at least 30°C higher than the steam temperature in the second compartment. Claim 7 A hydrocarbon compound mixture according to any one of claims 1 to 6, wherein the average residence time of the reaction mixture in the first compartment is 30 to 240 minutes, preferably 90 to 150 minutes. Claim 8 A hydrocarbon compound mixture according to any one of claims 1 to 7, wherein the average residence time of the reaction mixture in the second compartment is 30 to 240 minutes, preferably 90 to 150 minutes. Claim 9 A hydrocarbon compound mixture according to any one of claims 1 to 8, wherein the device comprises three different compartments, the third compartment having a lower steam temperature than the second compartment, and the second compartment and the third compartment have one or more interconnecting devices so that steam formed in the second compartment can move to the third compartment and liquid formed in the third compartment can return to the second compartment. Claim 10 A hydrocarbon compound mixture according to any one of claims 1 to 9, wherein the steam outlet temperature of the third compartment is set to a range of 230°C or higher and 270°C or lower, preferably 240°C or higher and 260°C or lower. Claim 11 A hydrocarbon compound mixture according to any one of claims 1 to 10, wherein the steam outlet temperature of the device where condensation of step C) occurs is set to a value of less than 180°C. Claim 12 A mixture of hydrocarbon compounds according to any one of claims 1 to 11, wherein the condensation of step C) takes place in more than one condensation device, and at least two of these condensation devices are operated at different temperatures. Claim 13 A hydrocarbon compound mixture according to any one of claims 1 to 12, wherein the process for obtaining the hydrocarbon compound mixture is a continuous process. Claim 14 A hydrocarbon compound mixture according to any one of claims 1 to 13, wherein all of the at least two compartments are arranged such that the first compartment is at the lowest position and the successive compartment(s) are located above each previous compartment. Claim 15 In any one of claims 1 to 14, the first compartment is a hydrocarbon compound mixture heated by an electric heater. Claim 16 In any one of claims 1 to 15, the first compartment and the second compartment are a mixture of hydrocarbon compounds heated by an electric heater. Claim 17 A hydrocarbon compound mixture according to any one of claims 1 to 16, wherein the process for obtaining the hydrocarbon compound mixture does not include the step of physically removing wax from any compartment. Claim 18 In any one of claims 1 to 17, the plastic waste is a mixture of hydrocarbon compounds that is post-consumer mixed plastic waste. Claim 19 A method for converting plastic waste into a liquid hydrocarbon compound mixture, wherein the liquid hydrocarbon compound mixture has a cloud point of 15°C or less when measured according to ASTM D2500-23 and is transparent in a layer of 40 mm thickness at 20°C according to ASTM D2500-23, which is a standard test method for measuring cloud point. Claim 20 A method for converting plastic waste into a liquid hydrocarbon compound mixture according to claim 19, comprising: A) a step of melting and degassing the plastic waste; B) a step of pyrolicing the melted plastic waste within a device, wherein the device comprises at least two different pyrolicing compartments in which pyrolicing vapor is generated, wherein the vapor in the first compartment among the compartments has a higher temperature than the vapor in the second compartment, and the at least two compartments are connected to each other so that the vapor formed in the first compartment moves to the second compartment and the liquid formed in the second compartment returns to the first compartment; and C) a step of condensing the vapor generated in the last compartment among the at least two compartments to obtain a liquid hydrocarbon compound mixture. Claim 21 A method for converting plastic waste into a liquid hydrocarbon compound mixture, comprising, in accordance with any one of claims 4 to 17, a process step according to claim 19 or 20. Claim 22 A method for converting plastic waste into a liquid hydrocarbon compound mixture, wherein the method is a continuous process, and the quality of the hydrocarbon compound mixture is controlled by applying: i) a step of adjusting the steam temperature in the first compartment to a range of 400°C or higher and 500°C or lower; ii) a step of determining the quality of the hydrocarbon compound mixture obtained after process step C) by applying a method of measuring a quality parameter correlated with the amount of a high molecular weight compound having a boiling point of 410°C or higher in the hydrocarbon compound mixture; and iii) a step of gradually increasing or decreasing the steam temperature in the first compartment so that the quality parameter reaches a value corresponding to a predetermined quality parameter threshold. Claim 23 Use of a mixture of hydrocarbon compounds according to any one of claims 1 to 18 as a feedstock for a refinery crude unit or a steam cracker of a refinery.

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