Hydrocarbon compound mixtures with improved properties obtained from plastic waste

Abstract

The invention relates to a mixture of hydrocarbon compounds having a cloud point of ≤ 15 °C according to the relevant standard test method for measuring the cloud point and being transparent in a layer of 40 mm thickness at 20 °C, which mixture is obtained by a process for converting plastic waste into a liquid mixture of hydrocarbon compounds. The invention also relates to a process for converting plastic waste into such a liquid mixture of hydrocarbon compounds and to the use of the mixture of hydrocarbon compounds as feedstock for a crude oil unit or a steam cracking unit of a refinery.

Description

Technical Field

[0001] This invention relates to a hydrocarbon compound mixture with improved properties, obtained through a process of converting plastic waste into a liquid hydrocarbon compound mixture. Background Technology

[0002] Over the past few decades, global production of plastic materials has increased dramatically. Plastic materials offer significant advantages, such as chemical and mechanical stability and lightweight properties, and their performance can be tuned during production to meet the needs of various applications. However, after use, most plastic materials currently end up in incineration or landfills, or even ultimately enter the natural world. Today, plastic materials are often made from fossil fuels, and a large portion of produced plastics is still designed for single use only. According to data from the European Commission (published on its website in 2023), Europe generates nearly 26 million tons of plastic waste annually, and the European Commission is addressing the negative impacts of this plastic waste through a number of policies.

[0003] Numerous attempts have been made to reuse plastic materials through recycling and create a circular process that uses recycled plastics as raw materials for new plastic materials. One method of this circular process involves converting waste plastic materials into oily hydrocarbon mixtures through thermal decomposition or pyrolysis. These mixtures can be used as alternative feedstocks for crude oil units or steam cracking units in oil refineries. For this reuse to be achieved, the hydrocarbon mixtures must meet certain quality requirements, and these quality requirements become more important the higher the proportion of the hydrocarbon mixtures in the feedstock of crude oil units or steam cracking units in oil refineries.

[0004] Several processes are known to convert waste plastic materials into oil products through thermal decomposition or pyrolysis.

[0005] US20160024390A1 discloses a two-stage pyrolysis apparatus for the continuous conversion of hydrocarbons into condensable, non-condensable, and solid hydrocarbons. The apparatus includes at least one extruder, a continuous process thermal kiln reactor, and a unit for conveying the hydrocarbons through the apparatus. The extruder is capable of providing shear force and heat and has three or more processing zones, with the extruder and the kiln reactor in fluid communication. The hydrocarbons are maintained within defined temperature and residence time ranges in each zone, wherein the extruder has at least three zones and the kiln reactor includes at least two zones. During the process, wax is removed from the reactor as a solid substance.

[0006] WO2019202546A1 discloses a pyrolysis apparatus for the thermal depolymerization of plastic materials. The apparatus includes a sealed container of a reactor connected to a feeder for supplying the plastic material, and the reactor container has an outlet for the gaseous products generated during depolymerization. The apparatus is also equipped with a mechanical stirrer and an outlet for removing unevaporated heavier fractions.

[0007] WO2022013712A1 discloses a waste pyrolysis method. The method includes providing a screw compressor suitable for heating the material by mechanical shearing; a reactor downstream of the screw compressor, suitable for heating the material under anaerobic conditions by heating the reactor wall; heating the material to an outlet temperature and increasing the pressure to an outlet pressure in the screw compressor; and thermally degrading the material in the reactor, wherein the screw compressor causes the material to reach extreme conditions at the outlet temperature and outlet pressure, thereby causing pyrolysis during pressure reduction and the formation of gaseous hydrocarbons within the connecting elements.

[0008] US20210189252A1 and US20210189254A1 disclose a circular economy method for recovering waste polyethylene and polypropylene plastics through refinery operations. Typical pyrolysis oils were obtained from commercial sources, and their properties were summarized. These pyrolysis samples were prepared by thermal decomposition of waste plastics, primarily containing polyethylene and polypropylene, in a pyrolysis reactor at approximately 400°C–600°C. The 99.5% final boiling point of these samples is 888°C. o F and 1079 o Between F, which corresponds to approximately 475℃ and 581℃.

[0009] The aforementioned published documents either fail to mention the quality of the pyrolysis oil produced by the disclosed process, or reveal certain characteristics of the pyrolysis oil indicating the presence of a large amount of high-boiling-point (above 450°C) fractions. The large amount of such high-boiling-point fractions suggests incomplete pyrolysis and the presence of a high proportion of long-chain hydrocarbons, such as waxes. Summary of the Invention

[0010] The object of this invention is to provide a mixture of hydrocarbon compounds obtained from plastic waste, which has improved properties and can be used extensively as a substitute for fossil feedstocks in refinery and steam cracking unit operations.

[0011] Another object of the present invention is to provide a process for converting plastic waste into hydrocarbon compound materials, through which hydrocarbon compound materials with improved properties can be obtained.

[0012] Therefore, we have discovered a mixture of hydrocarbon compounds with improved properties obtained from plastic waste, as well as process steps for obtaining such a mixture of hydrocarbon compounds.

[0013] In a first aspect of the invention, we have discovered a mixture of hydrocarbon compounds that, according to relevant standard test methods for measuring cloud point, has a cloud point ≤15°C and is transparent at 20°C in a 40 mm thick layer, the mixture being obtained by a process of converting plastic waste into a liquid mixture of hydrocarbon compounds.

[0014] More specifically, we have discovered a mixture of hydrocarbon compounds that has a cloud point of ≤15°C as determined by ASTM D2500-23, and is transparent at 20°C in a 40 mm thick layer according to the ASTM D2500-23 standard test method for measuring cloud point. This mixture is obtained through a process that converts plastic waste into a liquid mixture of hydrocarbon compounds.

[0015] A high cloud point is a marker of high molecular weight and / or long carbon chain fractions in a mixture of hydrocarbons, such as waxes, which tend to precipitate from oily hydrocarbon mixtures. The precipitation of these fractions can contaminate storage, transportation, and conveying equipment in production plants, as well as transportation equipment for further processing and facilities in refineries or steam cracking units; therefore, such contamination needs to be minimized.

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

[0017] As another aspect of the invention, we have discovered a hydrocarbon compound mixture in which 99.5 wt% of the mixture has a final boiling point ≤430°C, preferably ≤420°C, even more preferably ≤410°C, and even more preferably ≤400°C.

[0018] Specifically, we have discovered a hydrocarbon mixture in which 99.5 wt% of the hydrocarbon mixture has a final boiling point (measured according to ASTM D2887-22) of ≤430°C, preferably ≤420°C, even more preferably ≤410°C, and even more preferably ≤400°C.

[0019] The hydrocarbon compound mixtures according to the present invention can be obtained by employing a process that includes specific process steps.

[0020] According to a preferred embodiment of the present invention, the hydrocarbon compound mixture is obtained by a process comprising the following steps: A) Melt and degas the plastic waste. B) Pyrolysis of molten plastic waste in an apparatus comprising at least two different pyrolysis chambers, in which pyrolysis vapors are generated, wherein the vapor temperature in the first chamber is higher than the vapor temperature in the second chamber, and the at least two chambers are interconnected to allow vapors formed in the first chamber to move to the second chamber and to allow liquids formed in the second chamber to return to the first chamber. C) The vapor generated in the last of the at least two compartments is condensed to obtain a mixture of liquid hydrocarbon compounds.

[0021] In addition to these process steps, preparing the plastic waste for these steps is also beneficial. Advantageously, the plastic waste is first heated and compressed in a densification unit. The applied heat causes some unwanted gases and water to evaporate and reduces the viscosity of the plastic waste, allowing it to begin to melt.

[0022] In step A), the plastic waste is then further heated until it is essentially 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, applicable to many common plastic waste mixtures, the final temperature setting for step A) is in the range of 220°C. o C to 340 o C, preferably 240 o C to 320 o C. The temperature range mentioned above refers to the temperature at the end of this process step, i.e., the temperature at which the material reaches its final temperature. When the material enters the unit performing step A), its temperature may still be low due to the previous preparation steps. The material will be heated within the unit performing step A) until the temperature reaches the set point. The material temperature entering the unit performing step A) can, for example, be between 150°C and 160°C. o C to 200 o Between C.

[0023] During the melting and degassing steps, the viscosity of the mixture is further reduced, making it easier to transport to the compartment where the actual pyrolysis takes place. Furthermore, this prevents specific corrosive gases and / or air from entering the pyrolysis compartment.

[0024] In process step B), the molten plastic waste undergoes a controlled decomposition or pyrolysis reaction. According to the invention, this pyrolysis reaction is carried out in an apparatus having at least two distinct compartments. This means that these compartments are physically isolated, allowing for precise and independent control of the process conditions, particularly the temperature, in each compartment. The temperature of the first compartment is typically set higher than that of the second compartment. In this context, the first compartment refers to the compartment into which the material first enters after step A). ​​The higher temperature, compared to the temperature applied in process step A), causes the molten plastic material to begin a rapid pyrolysis reaction. Due to vapor pressure, the vapors generated by this pyrolysis reaction continuously exit the first compartment through the interconnection with the second compartment and are further processed in the second compartment.

[0025] In the second compartment, because the temperature of the second compartment is lower than that of the first compartment, a portion of the vapor leaving the first compartment is condensed. As a result, an oil phase accumulates at the bottom of the second compartment. This oil phase further pyrolyzes in the second compartment under the control of the applied temperature setting. According to a preferred embodiment of the invention, the vapor leaving the first compartment is introduced into the oil phase of the second compartment through a pipe immersed in the oil phase. In this way, the vapor is cooled to the temperature of the second compartment more effectively, and a large amount of vapor is prevented from leaving the second compartment without further exposure to the pyrolysis conditions of the second compartment.

[0026] The apparatus for performing the pyrolysis step also includes an interconnection between the second and first compartments, which allows liquid (such as an oil phase) present in the second compartment to return to the first compartment. The liquid return is preferably carried out in a controlled manner, for example, by means of a valve within the interconnection, 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.

[0027] The process steps employed according to the present invention allow operators to adjust multiple process parameters in a certain way, thereby enabling precise control of the throughput of the apparatus and the properties of the resulting hydrocarbon mixture. In particular, the feed rate of the first compartment, the temperatures of the first and second compartments, and the reflux of liquid material from the second compartment to the first compartment are all relevant variables that enable the production of the desired product quality.

[0028] According to a preferred embodiment of the present invention, an inventive hydrocarbon compound mixture is obtained by the following process: wherein the steam temperature in the first compartment is set in the range of ≥400°C and ≤500°C, preferably in the range of ≥420°C and ≤460°C.

[0029] According to a preferred embodiment of the present invention, an inventive hydrocarbon compound mixture is obtained by the following process: wherein the steam temperature in the second compartment is set in the range of ≥350°C and ≤450°C, preferably in the range of ≥370°C and ≤400°C.

[0030] Fine-tuning of such temperature settings depends on the composition of the plastic waste, the required throughput of the unit, and the rate of liquid reflux from the second compartment to the first compartment. Skilled operators can optimize these process variables by measuring the desired mass of the final hydrocarbon mixture as a function of these small variations.

[0031] As can be clearly seen from the above description of the process steps, the pyrolysis reaction in the first compartment is carried out under more stringent conditions, resulting in more decomposition occurring in the first compartment compared to the second compartment. This means that the residence time and temperature conditions in the first compartment are typically set to efficiently decompose most of the plastic waste. Then, the residence time and temperature settings in the second compartment are adjusted to fine-tune the pyrolysis reaction, ensuring the decomposition reaches the desired extent and optimizing the quality of the final hydrocarbon mixture.

[0032] According to a preferred embodiment of the present invention, an inventive mixture of hydrocarbon compounds is obtained by the following process: wherein the steam temperature in the first compartment is at least 10°C higher than the steam temperature in the second compartment, preferably at least 20°C higher, and even more preferably at least 30°C higher.

[0033] Besides temperature, residence time is also a crucial parameter controlling the quality of the final hydrocarbon mixture. The residence time of the pyrolysis mixture in the first compartment is particularly affected by the feedstock added to that compartment, the reflux ratio of oil from the second compartment, and the temperature applied in the first compartment. A sufficiently high degree of decomposition is generally desirable to obtain a homogeneous liquid hydrocarbon mixture, but the degree of decomposition should not be excessive, as further cracking in refinery crude oil units or steam cracking units can usually be carried out under energy-favorable conditions and can be finely tuned to obtain the final product required by the refinery or steam cracking unit. The advantage of the apparatus and process steps described in this invention is that a variety of high-quality hydrocarbon mixtures can be flexibly obtained by changing the above process conditions (including the residence time in each compartment).

[0034] According to a preferred embodiment of the invention, an inventive hydrocarbon compound mixture is obtained by a process in which the average residence time of the reaction mixture in a first compartment is between 30 minutes and 240 minutes, preferably between 60 minutes and 180 minutes, and even more preferably between 90 minutes and 150 minutes.

[0035] According to another preferred embodiment of the invention, an inventive hydrocarbon compound mixture is obtained by a process in which the average residence time of the reaction mixture in the second compartment is between 30 minutes and 240 minutes, preferably between 60 minutes and 180 minutes, and even more preferably between 90 minutes and 150 minutes.

[0036] The aforementioned average residence time refers to the residence time calculated based on the feed of liquid or molten plastic waste obtained from the previous process step into the corresponding first or subsequent compartment and the volume of liquid in that compartment. In continuous processes under steady-state conditions, the residence time can be determined based on the feed, without taking into account the backflow from the second compartment to the first compartment and the volume of liquid in the first compartment.

[0037] By using a device comprising an additional compartment in which pyrolysis can take place, the quality of the final hydrocarbon mixture can be further improved. According to a preferred embodiment of the invention, an inventive hydrocarbon mixture is obtained by a process in which the device comprises three distinct compartments, the steam temperature of the third compartment being lower than that of the second compartment, and the second and third compartments having one or more interconnections to allow steam formed in the second compartment to move to the third compartment and to allow liquid formed in the third compartment to return to the second compartment.

[0038] The options for process control described in the section concerning the interconnection between the first and second compartments, with appropriate modifications, also apply to the interconnection between the third and second compartments. The third compartment allows for further fine-tuning of the specifications and quality of the final product and enables the production of a more homogeneous mixture of hydrocarbons with the desired cloud point and final boiling point. In a preferred embodiment of the invention, the third compartment may be designed as one or more reflux condensers, wherein, depending on the temperature setting, some or all of the vapor leaving the second compartment is condensed and allowed to return to the second compartment to continue the pyrolysis reaction until the pyrolysis reaction reaches a stage where some of the vapor entering the one or more reflux condensers no longer condenses, but leaves the reflux condenser and is allowed to proceed to condensation step C).

[0039] In principle, the two or more compartments can be arranged in various ways or geometries, including horizontally or vertically, and may even maintain a certain physical distance from each other. However, from an economic point of view, it is advantageous to arrange the compartments close to each other and vertically.

[0040] According to a preferred embodiment of the invention, an inventive hydrocarbon compound mixture is obtained by a process in which the at least two compartments are arranged in such a way that the first compartment is located at the lowest level, while subsequent compartments are located above their respective preceding compartments.

[0041] In process step C), the steam passing through the cooling unit in the last compartment is condensed, thus obtaining a liquid hydrocarbon mixture. This cooling can be achieved using standard cooling devices such as shell-and-tube heat exchangers.

[0042] According to a preferred embodiment of the present invention, an inventive hydrocarbon compound mixture is obtained by the following process: wherein the outlet temperature of the unit for condensation in step C) is set to a value below 180°C.

[0043] If fractionation of the condensate is required, step C) can be arranged as a cascaded condensation step. In this case, additional condensers cooled to different temperatures can be used. The final outlet temperature of the condenser participating in process step C) is preferably set to ambient temperature, such as 20°C. o C to 30 o Between C.

[0044] According to a preferred embodiment of the present invention, an inventive mixture of hydrocarbon compounds is obtained by a process in which the condensation of process step C) is carried out in more than one condensation unit, and at least two of such condensation units operate at different temperatures.

[0045] As can be clearly seen from this description, the quality of the hydrocarbon mixture according to the present invention can be stably adjusted and optimized by fine-tuning process conditions, such as reaction temperature, residence time in different compartments, and reflux ratio between different compartments. This fine-tuning is even more achievable if the process is run continuously, and the process described herein possesses this capability, thus producing hydrocarbon mixtures of higher quality.

[0046] According to a preferred embodiment of the present invention, an inventive mixture of hydrocarbon compounds is obtained by a process wherein the process of obtaining the mixture is a continuous process.

[0047] Since the pyrolysis reaction requires a continuous supply of heat energy, a suitable energy source is crucial for the economical and efficient operation of the process described in this invention. Typically, this energy can be provided in the form of fuel (e.g., through a gas or oil burner). Research according to this invention has found that heating can be best achieved via an electric heating device. Compared to fuel-based, particularly syngas-based, heating devices can be adjusted more precisely and rapidly, which has proven to be significantly advantageous for fine-tuning the temperature settings in different compartments (especially the first compartment), where the main part of the pyrolysis reaction is taking place and the temperature cannot be further controlled by a reflux condenser.

[0048] According to a preferred embodiment of the present invention, an inventive mixture of hydrocarbon compounds is obtained by a process in which a first compartment is heated by an electric heater.

[0049] According to another preferred embodiment of the invention, an inventive mixture of hydrocarbon compounds is obtained by a process in which the first and second compartments are heated by an electric heater.

[0050] Some known plastic waste pyrolysis processes attempt to reduce the amount of wax formed during pyrolysis by separating waxy substances in the early stages of the process and recovering these waxes as solid products. However, in these processes, additional waxes may form in the later stages of pyrolysis or may not be adequately removed. Therefore, these processes typically produce pyrolysis oil containing significant amounts of waxes, resulting in an incompletely homogeneous final pyrolysis oil, especially at lower temperatures. The hydrocarbon mixture according to the invention is obtained by a process that, instead of separating waxes as side-stream products, degrades them in a controlled manner to a degree that they have no significant impact on the final hydrocarbon mixture. For the same reason, the yield of the final hydrocarbon mixture is also higher than if the waxes were removed as solids and not further pyrolyzed in the process.

[0051] According to a preferred embodiment of the present invention, an inventive mixture of hydrocarbon compounds is obtained by a process in which the process of obtaining the mixture does not include a step of physically removing wax from any pyrolysis chamber.

[0052] The plastic waste that can be used to produce this inventive hydrocarbon mixture can be any plastic waste, such as 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 consumer. Waste plastics generated by industrial processes are generally well-defined and may contain fewer unwanted byproducts. Waste plastics generated by consumers typically contain a variety of different plastic polymers and contain more unwanted byproducts, such as food scraps. Because plastic waste collection systems vary from country to country and even from community to community, the composition of the plastic waste to be pyrolyzed may also differ. After collection, plastic waste is typically pretreated to separate it from metals, paper, and other components. According to the invention, any such common pretreated plastic waste can be processed into the hydrocarbon mixture of the invention.

[0053] According to a preferred embodiment of the present invention, an inventive hydrocarbon compound mixture is obtained by the following process: wherein the plastic waste is post-consumer mixed plastic waste.

[0054] The hydrocarbon compound mixture obtained according to the present invention represents an element of the concept of a circular economy, which aims to recycle plastic polymers and convert them into new plastic polymers. According to this circular economy concept, plastic polymers are collected after use and converted into this inventive hydrocarbon compound mixture by applying the process steps described in this disclosure. Subsequently, these hydrocarbon compound mixtures can be fed into the crude oil unit of a refinery, where they undergo hydrotreating and further cracking to produce suitable feedstocks, such as feedstocks for steam cracking units, or directly fed into a steam cracking unit to generate new monomers, which can then be processed into new plastic polymers.

[0055] Therefore, one embodiment of the present invention is to use the hydrocarbon compound mixture described in the present invention as a feedstock for a refinery crude unit or a steam cracking unit. Detailed Implementation

[0056] In the following description, an apparatus for performing the process steps described in this disclosure will be presented in more detail. This description of the apparatus is not intended to limit the general disclosure of the invention herein, but is merely for the purpose of illustrating a preferred embodiment in which the process steps described herein can be performed. Figure 1 A description of this device is shown.

[0057] Plastic waste is fed into compactor 101, for example, via a conveyor belt. The compactor compresses the plastic waste. Compression can be achieved by one or more screw conveyors constituting compactor 101. The compression process heats the residual polymer product due to friction. Heating may cause at least some of the polymer product to melt, but the heating temperature is low enough that substantial chemical degradation does not occur. However, heating may cause the polymer product to generate some water vapor, which is preferably removed. The compactor may be configured to heat the residual polymer product to a temperature in the range of 150°C to 200°C. The compressed, heated, and possibly partially melted polymer product mixture is then transferred, for example, through a heated conduit to degasser 102, so that the partially melted polymer mixture will not solidify within the conduit.

[0058] Degasser 102 includes a screw conveyor for conveying residual polymer product from the inlet to the degasser outlet. Degasser 102 also includes a heater, such as an electric heater, for heating the polymer product to a final temperature in the range of 240°C to 330°C. A preferred outlet temperature for the molten residual polymer product at the degasser outlet is in the range of 250°C to 270°C, preferably 255°C to 265°C. Heating in degasser 102 causes almost all moisture and other unwanted volatiles and non-condensable gases to evaporate. These unwanted volatiles may include unwanted vapors such as corrosive gases and vapors. Removing these unwanted volatiles allows downstream components of the unit (such as pyrolysis reactors) to use materials with lower corrosion resistance, thus providing both process and economic benefits.

[0059] To improve the quality of the hydrocarbon mixture produced in the unit, calcium oxide or other alkaline substances can be fed into the compactor 101 or the degasser 102. Adding such alkaline substances can neutralize the acidic gases produced during pyrolysis, especially those produced during the pyrolysis of chlorinated polymers (such as polyvinyl chloride).

[0060] In the illustrated apparatus, the first compartment of the process described in this invention—the pyrolysis reactor 103—is arranged at an angle so that the liquid mixture level within the reactor does not reach the top of the reactor. The pyrolysis reactor 103 includes two reactor screw conveyors for moving and mixing the liquid mixture and conveying solid residues (especially carbon black generated during the pyrolysis reaction) to the outlet. The pyrolysis reactor 103 is heated by a heater (such as an electric heater) to heat the reaction mixture to a temperature range of ≥400°C to ≤500°C, thereby generating pyrolysis vapor. The temperature within the pyrolysis reactor can vary between the liquid phase at the reactor inlet, the liquid phase at the top of the reactor, and the vapor phase. The aforementioned temperature range refers to the temperature of the vapor phase within the reactor and applies to all embodiments of the invention described in this specification. Since the higher temperature vapor from the preceding compartment may require some time to adjust to the new temperature setting applied in the successive compartments, the vapor temperature within the compartment may not always be constant. In such cases, the vapor temperature at the outlet of the respective compartment should be used to determine the temperature range described in this specification.

[0061] Upon heating, the reaction mixture gradually pyrolyzes, forming vapor containing hydrocarbon compounds. This vapor exits the pyrolysis reactor toward the second compartment (here, the oil reactor), where the liquid oil phase and vapor phase reappear.

[0062] Oil reactor 104 is a tank configured to separate pyrolysis vapor received from pyrolysis reactor 103 into vapor and liquid components. Oil reactor 104 may include a stirrer for mixing the contents. Pyrolysis vapor enters oil reactor 104 through a top nozzle and / or through a dip pipe leading into the liquid phase of the tank. The tank temperature can be adjusted 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 in oil reactor 104 may be controlled, for example, by means of an electric heater. An interconnection is provided between oil reactor 104 and pyrolysis reactor 103, allowing controlled reflux from oil reactor 104 to pyrolysis reactor 103. In this way, a portion of the liquid in the oil reactor can be further exposed to the pyrolysis conditions in pyrolysis reactor 103. Similarly, in the oil reactor, the temperature can vary between the oil phase and the vapor phase, and the aforementioned temperature refers to the temperature in the vapor phase.

[0063] In the illustrated apparatus, the oil reactor 104 includes two separator outlets for conveying the steam generated in the oil reactor 104 through respective pipes to two reflux condensers 105a and 105b. The same pipes guide the condensate from the reflux condensers 105a and 105b back to the oil reactor 104 through the liquid outlets of the reflux condensers. Therefore, these liquid outlets also function as steam inlets. The reflux condensers 105a and 105b are configured to condense at least a portion of the steam component from the oil reactor 104 into a liquid component. The apparatus is equipped with two reflux condensers so that the apparatus can continue to operate even when one of the reflux condensers can be shut off for cleaning or maintenance. These two reflux condensers can be configured as shell-and-tube heat exchangers, with the tube side containing pyrolysis steam and the shell side containing hot oil for temperature control.

[0064] The steam exiting reflux condensers 105a and 105b is piped to condensers 106a and 106b, where it is condensed into liquid pyrolysis oil. In the illustrated apparatus, the condensers are replicated to allow for maintenance and cleaning of one of the condensers while the apparatus continues to operate. The condensers can be designed as common shell-and-tube heat exchangers. If fractionation of the pyrolysis oil is required, the temperatures of condensers 106a and 106b can be set in, for example, a range of ≥130°C and ≤180°C. Within this temperature range, the steam passing through the condensers can be further condensed in condenser 107, which is set at a lower temperature, to obtain lighter fractions of the pyrolysis products, such as naphtha.

[0065] Another aspect of the present invention is to provide a process for converting plastic waste into a mixture of liquid hydrocarbon compounds, wherein the mixture has a cloud point ≤15°C and is transparent in a 40 mm thick layer at 20°C, according to relevant standard test methods for measuring cloud point.

[0066] A particular aspect of the invention is to provide a process for converting plastic waste into a mixture of liquid hydrocarbon compounds, wherein the mixture has a cloud point ≤15°C as determined by ASTM D2500-23, and is transparent in a 40 mm thick layer at 20°C according to the standard test method for measuring cloud point of ASTM D2500-23.

[0067] According to a preferred embodiment, an inventive process has been discovered, which includes the following steps: A) Melt and degas the plastic waste. B) Pyrolysis of molten plastic waste in an apparatus comprising at least two different pyrolysis chambers, in which pyrolysis vapors are generated, wherein the vapor temperature in the first chamber is higher than the vapor temperature in the second chamber, and the at least two chambers are interconnected to allow vapors formed in the first chamber to move to the second chamber and to allow liquids formed in the second chamber to return to the first chamber. C) The vapor generated in the last of the at least two compartments is condensed to obtain a mixture of liquid hydrocarbon compounds.

[0068] According to a preferred embodiment, the present invention includes A process for converting plastic waste into a mixture of liquid hydrocarbon compounds, wherein the mixture has a cloud point ≤15°C as determined by ASTM D2500-23, and is transparent at 20°C in a 40 mm thick layer according to the ASTM D2500-23 standard test method for measuring cloud point, wherein the process includes the following steps: A) Melt and degas the plastic waste. B) Pyrolysis of molten plastic waste in an apparatus comprising at least two different pyrolysis chambers, in which pyrolysis steam is generated, wherein the steam temperature in the first chamber is higher than the steam temperature in the second chamber, and the at least two chambers are interconnected to allow steam formed in the first chamber to move to the second chamber and to allow liquid formed in the second chamber to return to the first chamber, wherein the steam temperature in the first chamber is set in the range of ≥400°C and ≤500°C, preferably in the range of ≥420°C and ≤460°C, and the steam temperature in the second chamber is set in the range of ≥350°C and ≤450°C, preferably in the range of ≥370°C and ≤400°C. C) The steam generated in the last of the at least two compartments is condensed to obtain a liquid hydrocarbon mixture. Some plastic waste pyrolysis processes known in the art involve adding heated sand, molten salt, or other heat carriers to the molten plastic waste to increase or regulate the temperature of the pyrolysis mixture, or to promote heat distribution within the pyrolysis mixture. The disadvantage of adding such heat carriers is the need for additional process steps to separate them. The process of the present invention does not require the addition of such heat carriers and obtains a high-quality liquid hydrocarbon mixture without their addition.

[0069] Therefore, according to another preferred embodiment, we have discovered a process for converting plastic waste into a mixture of liquid hydrocarbon compounds, wherein the mixture has a cloud point ≤15°C as determined by ASTM D2500-23, and is transparent at 20°C in a 40 mm thick layer according to the ASTM D2500-23 standard test method for measuring cloud point, wherein the process includes the following steps: A) Melt and degas the plastic waste. B) Pyrolysis of molten plastic waste in an apparatus comprising at least two different pyrolysis chambers, in which pyrolysis vapors are generated, wherein the vapor temperature in the first chamber is higher than the vapor temperature in the second chamber, and the at least two chambers are interconnected to allow vapors formed in the first chamber to move to the second chamber and to allow liquids formed in the second chamber to return to the first chamber. C) Condensing the vapor produced in the last of the at least two compartments to obtain a mixture of liquid hydrocarbon compounds. Furthermore, heated sand, molten salt, or other heat carriers are not added to the pyrolysis reaction.

[0070] According to another preferred embodiment, an innovative process has been discovered, wherein the process is a continuous process, and wherein the quality of the hydrocarbon compound mixture is controlled by employing the following steps: i) Adjust the steam temperature in the first compartment to a range of ≥400℃ and ≤500℃. ii) The mass of the hydrocarbon mixture obtained after process step C) is determined by employing a method for measuring a mass parameter related to the amount of high molecular weight compounds with a boiling point ≥410℃ in the hydrocarbon mixture. iii) Gradually increase or decrease the steam temperature in the first compartment until the quality parameter reaches a value corresponding to the predetermined quality parameter threshold.

[0071] Suitable methods for measuring mass parameters related to the content of high molecular weight compounds with a boiling point ≥410°C in a hydrocarbon 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 this specific embodiment, other methods that may yield similar mass determination results may also be used. For example, if the cloud point is measured using a method such as ASTM D2500-23, and the transparency of the final hydrocarbon mixture does not meet the transparency requirements of that method, the vapor temperature in the first pyrolysis chamber can be increased or decreased until the transparency requirements are met, and then the vapor temperature in the first pyrolysis chamber can be further increased or decreased until the desired mass parameter threshold is reached. This desired mass parameter threshold may be, for example, a cloud point ≤15°C, but other mass parameter thresholds corresponding to the quality specifications established by the hydrocarbon mixture manufacturer may also be used.

[0072] All preferred aspects and embodiments relating to hydrocarbon mixtures and process steps for obtaining hydrocarbon mixtures as described in this invention disclosure should also be considered preferred aspects and embodiments of this inventive process, whether individually or in combination as described in the claims of this invention.

Claims

1. A mixture of hydrocarbon compounds, wherein the cloud point of the mixture is ≤15°C as determined by ASTM D2500-23, and the mixture is transparent at 20°C in a 40 mm thick layer according to the ASTM D2500-23 standard test method for measuring cloud point, the mixture being obtained by a process of converting plastic waste into a liquid mixture of hydrocarbon compounds.

2. A mixture of hydrocarbon compounds according to any one of the preceding claims, wherein 99.5 wt% of the mixture in the hydrocarbon mixture has a final boiling point ≤430°C.

3. A mixture of hydrocarbon compounds according to any one of the preceding claims, obtained by a process comprising the following steps: A) Melt and degas the plastic waste. B) Pyrolysis of molten plastic waste in an apparatus comprising at least two different pyrolysis chambers, generating pyrolysis vapors in the at least two chambers, wherein the vapor temperature in the first chamber is higher than the vapor temperature in the second chamber, and the at least two chambers are interconnected to allow vapors formed in the first chamber to move to the second chamber and to allow liquids formed in the second chamber to return to the first chamber. C) The vapor generated in the last of the at least two compartments is condensed to obtain a mixture of liquid hydrocarbon compounds.

4. The hydrocarbon compound mixture according to any one of the preceding claims, wherein the steam temperature in the first compartment is set in the range of ≥400°C and ≤500°C, preferably in the range of ≥420°C and ≤460°C.

5. The hydrocarbon compound mixture according to any one of the preceding claims, wherein the steam temperature in the second compartment is set in the range of ≥350°C and ≤450°C, preferably in the range of ≥370°C and ≤400°C.

6. The hydrocarbon compound mixture according to any one of the preceding claims, wherein the steam temperature in the first compartment is at least 10°C higher than the steam temperature in the second compartment, preferably at least 20°C higher, and even more preferably at least 30°C higher.

7. The hydrocarbon compound mixture according to any one of the preceding claims, wherein the average residence time of the reaction mixture in the first compartment is between 30 minutes and 240 minutes, preferably between 90 minutes and 150 minutes.

8. The hydrocarbon compound mixture according to any one of the preceding claims, wherein the average residence time of the reaction mixture in the second compartment is between 30 minutes and 240 minutes, preferably between 90 minutes and 150 minutes.

9. A hydrocarbon compound mixture according to any one of the preceding claims, wherein the device comprises three different compartments, and the vapor temperature of the third compartment is lower than that of the second compartment, the second and third compartments having one or more interconnections to allow vapor formed in the second compartment to move to the third compartment and to allow liquid formed in the third compartment to return to the second compartment.

10. The hydrocarbon compound mixture according to any one of the preceding claims, wherein the steam outlet temperature of the third compartment is set in the range of ≥230°C and ≤270°C, preferably in the range of ≥240°C and ≤260°C.

11. A mixture of hydrocarbon compounds according to any one of the preceding claims, wherein, The steam outlet temperature of the unit that performs condensation in step C) is set to a value below 180°C.

12. A hydrocarbon compound mixture according to any one of the preceding claims, wherein the condensation in step C) is carried out in more than one condensation unit, and wherein at least two condensation units operate at different temperatures.

13. A mixture of hydrocarbon compounds according to any one of the preceding claims, wherein the process for obtaining the mixture of hydrocarbon compounds is a continuous process.

14. A hydrocarbon compound mixture according to any one of the preceding claims, wherein all of the at least two compartments are arranged such that the first compartment is at the lowest level and subsequent compartments are located above their respective preceding compartments.

15. A mixture of hydrocarbon compounds according to any one of the preceding claims, wherein the first compartment is heated by an electric heater.

16. A mixture of hydrocarbon compounds according to any one of the preceding claims, wherein the first compartment and the second compartment are heated by an electric heater.

17. A hydrocarbon compound mixture according to any one of the preceding claims, wherein the process for obtaining the hydrocarbon compound mixture does not include a step of physically removing wax from any compartment of the compartment.

18. A mixture of hydrocarbon compounds according to any one of the preceding claims, wherein the plastic waste is post-consumer mixed plastic waste.

19. A process for converting plastic waste into a liquid hydrocarbon mixture, wherein the cloud point of the hydrocarbon mixture is ≤15°C as determined by ASTM D2500-23, and the hydrocarbon mixture is transparent at 20°C in a 40 mm thick layer according to the standard test method for measuring cloud point of ASTM D2500-23.

20. The process according to claim 19, wherein the process comprises the following steps: A) Melt and degas the plastic waste. B) Pyrolysis of molten plastic waste in an apparatus comprising at least two different pyrolysis chambers, generating pyrolysis vapors in the at least two chambers, wherein the vapor temperature in the first chamber is higher than the vapor temperature in the second chamber, and the at least two chambers are interconnected to allow vapors formed in the first chamber to move to the second chamber and to allow liquids formed in the second chamber to return to the first chamber. C) The vapor generated in the last of the at least two compartments is condensed to obtain a mixture of liquid hydrocarbon compounds.

21. The process according to claims 19 and 20, comprising the process steps according to any one of claims 4 to 17.

22. The process of claim 20, wherein the process is a continuous process, and wherein the mass of the hydrocarbon mixture is controlled by employing the following steps: i) Adjust the steam temperature in the first compartment to a range of ≥400℃ and ≤500℃. ii) Using a method for measuring mass parameters, determine the mass of the hydrocarbon mixture obtained after process step C), wherein the mass parameter is related to the amount of high molecular weight compounds with a boiling point ≥410°C in the hydrocarbon mixture. iii) Gradually increase or decrease the steam temperature in the first compartment until the quality parameter reaches a value corresponding to a predetermined quality parameter threshold.

23. Use of the hydrocarbon compound mixture according to any one of the preceding claims as feedstock for crude oil units or steam cracking units in oil refineries.

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