Pyrolysis system for efficient plastic waste recycling

Abstract

The present disclosure relates to a system for recycling a plastic feedstock by pyrolysis comprising at least a first vessel, and wherein the first vessel has an input for receiving the plastic feedstock, a first conveyer screw system configured for conveying the received plastic feedstock from a first end to a second end of the first vessel, and a first part and a second part, and wherein the first part is separated by the second part by a buffer space for building up a buffer of plastic feedstock inside the first vessel and / or to enable plastic feedstock of different sizes or melt temperatures to be mixed up before entering the second part.

Description

[0001] Pyrolysis system for efficient plastic waste recycling

[0002] Field of the disclosure

[0003] The present disclosure relates to a system for recycling a plastic feedstock by pyrolysis.

[0004] Background

[0005] In recent decades, the escalating global production and consumption of plastics have led to a critical environmental challenge: the proliferation of plastic waste. Despite increased efforts in recycling and waste management, a significant portion of plastic waste continues to end up in landfills, posing serious environmental risks and contributing to pollution of land and water ecosystems.

[0006] Traditional disposal methods, such as landfilling and incineration, while convenient, have significant drawbacks.

[0007] Landfills are finite resources and can quickly reach its filling capacity, leading to the need for additional land for waste disposal. Moreover, plastic waste in landfills can take hundreds to thousands of years to decompose, releasing harmful chemicals and greenhouse gases into the environment during the process. These are resources that could be recirculated in a circular economic model but rather lay fallow in a landfill.

[0008] Incineration involves burning plastic waste at high temperatures to generate heat or electricity. While incineration can be an effective method for reducing the volume of waste and recovering energy, it can also produce air pollutants and greenhouse gas emissions if not properly controlled.

[0009] Mechanical recycling has emerged as a widely adopted approach to mitigate the impacts of plastic waste by reusing plastic materials in manufacturing processes. However, mechanical recycling has limitations, particularly with regard to the quality and purity of recycled plastics. To address the growing plastic waste crisis, in addition to the traditional disposal methods and the mechanical plastic recycling methods, also chemical recycling methods have been proposed and used.

[0010] An example of chemical plastic waste recycling is plastic waste treatment by pyrolysis, which is a process wherein plastics are heated to high temperatures in the absence of oxygen, causing them to break down into smaller valuable molecules such as gases, liquid fuels, and char. In other words, pyrolysis is a thermal depolymerization process done in the absence of oxygen, i.e. an anaerobic process.

[0011] Hence pyrolysis offers a promising pathway to mitigate the environmental impacts of plastic waste while simultaneously recovering valuable resources.

[0012] However, the successful implementation of pyrolysis treatment is contingent upon addressing critical challenges, one of which is the presence of oxygen in the plastic feedstock. Oxygen can interfere with the pyrolysis process, leading to undesirable side reactions such as combustion and the formation of unwanted by-products. For instance, oxygen burns material and creates ash and CO2 instead of oil and char. Therefore, the removal of oxygen from the plastic feedstock before introduction into the hot zone(s) of a pyrolysis reactor is imperative to ensure the efficiency and efficacy of the pyrolysis treatment.

[0013] Especially for pyrolysis systems that apply a continuous feeding process, keeping air, containing oxygen, out while continuously feeding in feedstock material is a huge challenge.

[0014] In addition, present pyrolysis reactors generally require elaborate pre-processing equipment to prepare the plastic waste for pyrolysis, for instance to transform larger plastic pieces into smaller pieces. This could involve multi-stage shredders, grinders or milling machines, washing lines and dehydrators to reduce the size of the plastic materials and remove contaminants or non-plastic components. In some pyrolysis systems, a high selectivity is applied in the type and conditions of the materials fed into the reactor and plastic waste is pre- processed into fine particles / flakes to increase the bulk density of the waste material and hence reduce air gaps. Alternatively, pyrolysis is limited to low melting temperature materials or soft materials like LDPE, which rather limits the options of materials for pyrolysis.

[0015] A problem of using a pyrolysis reactor for recycling plastic is also that the pyrolysis process requires substantial energy inputs to heat the reactor to the temperatures necessary for thermal decomposition of plastic waste into gas or oil. Typical temperatures required for pyrolysis of plastics are in the range between 300°C and 650°C.

[0016] A further challenge is related to the recovery of oil from pyrolysis gas and the handling of the produced char, which is a by-product of plastic pyrolysis.

[0017] Indeed, the plastic waste may contain up to 95% of oil. However, the pyrolysis product that exits the pyrolysis reactor is generally in the form of a gas, also named pyrolysis gas or pyrolysis oil gas, and which is at about the same temperature as the reactor temperatures. To recover liquid pyrolysis oil, the hot pyrolysis gas exiting the reactor needs to be cooled. In general, the pyrolysis gas is transported to a cooling unit, i.e. a condenser, to be cooled to room temperature. This requires high energy cooling systems and constructions.

[0018] Further, plastic waste may contain up to 70% inorganic minerals which do not decompose during pyrolysis but rather combine with the char as a by-product. The char in generally sent to a cooling unit to be cooled from between 300°C-600°C to room temperature. Doing this also requires high energy cooling system and constructions.

[0019] The energy -intensive nature of pyrolysis not only contributes to the operating costs but also limits the scalability, ecological and economic viability of the pyrolysis facilities. Hence, there is room for improving equipment for plastic waste pyrolysis and for developing more robust pyrolysis reactors.

[0020] Summary

[0021] It is an objective of the present disclosure to provide a robust pyrolysis system wherein the selectivity in the type and conditions of the feedstock that can be received in the reactor is reduced when compared to prior art pyrolysis systems. A further objective of the present disclosure is to provide a pyrolysis reactor for plastic waste recycling wherein the energy efficiency is enhanced when compared to present pyrolysis reactors such that not only the overall cost for pyrolysis treatment may be reduced but also a more environment friendly pyrolysis treatment is obtained with reduced CO2 outputs.

[0022] The present disclosure is defined in the appended independent claims. The dependent claims define advantageous embodiments.

[0023] According to a first aspect of the disclosure, a system for recycling a plastic feedstock by pyrolysis comprising at least a first vessel is provided. The first vessel has an input for receiving the plastic feedstock, a first conveyer screw system configured for conveying the received plastic feedstock from a first end to a second end of the first vessel, and a first vessel part and a second vessel part, and wherein the first vessel part is separated by the second vessel part by a buffer space for building up a buffer of plastic feedstock inside the first vessel and / or to enable plastic feedstock of different sizes or melt temperatures to be mixed up before entering the second part.

[0024] A plastic feedstock has to be construed as pieces of solid plastic material that need to undergo a pyrolysis treatment. The pieces of material can for example be pieces of plastic waste and / or rubber waste, e.g. originating from used tyres. Generally, the first vessel part and the second vessel part of the first vessel correspond to respectively a first operational zone and a second operational zone of the first vessel, and the system is configured for operating within a first temperature range in the first operational zone and within a second temperature range in the second zone.

[0025] Typically, a temperature in the first operational zone is lower than a temperature in the second operational zone. For example, when the system is in operation, the first operational zone may have a temperature in a range between -25°C to 200°C, preferably between -10°C to 200°C, and the second operational zone may have a temperature in a range between 250°C to 650°C, more preferably wherein the second zone has a temperature in a range between 350°C and 550°C. Hence in the first zone, the temperature is generally too low for starting a pyrolysis reaction.

[0026] The buffer space inside the reactor according to the present disclosure has multiple advantages. Indeed, when the system is in use, the buffer space will be filled up with feedstock so as to enable feedstock of different sizes and / or melting temperatures to be mixed up before entering the second conveyer screw. Secondly, by creating such a buffer space filled with feedstock material, due to the effect of the first conveyer screw, the feedstock material in the buffer space is compressed and forms a seal within the reactor which blocks gases produced in the second part of the reactor to flow to the first part of the reactor and also inhibits air / vapour from the first part to flow into the second part of the reactor. Thirdly the buffer space mitigates blocking of the screw when large sized feedstock that is not pretreated is fed into the reactor as they may contain stones, metal and other solid particles. Additionally, the buffer space enables the ability to regulate process speed and hence efficiency by using two separate motors to the screws.

[0027] Advantageously, the selectivity in the type and conditions of the plastic feedstock that can be received by the system is reduced, and hence pre-processing activities of the feedstock can be strongly reduced. As a result, the treatment of plastic waste with pyrolysis may become economically viable.

[0028] In embodiments, the first conveyer screw system may comprise a first conveyor screw extending from a begin side to an end side of the first conveyer screw and a second conveyor screw extending from a begin side to an end side of the second conveyer screw, and wherein the first part and second part of the first vessel accommodate respectively the first conveyor screw and the second conveyor screw. The first and second conveyer screw are oriented in a same direction and wherein the begin side of the second conveyer screw is separated from the end side of the first conveyer screw so as to create a space between the first and second conveyer screw, and wherein the space between the first and second conveyer screw is forming the buffer space.

[0029] Advantageously, by providing a first and a second motor for respectively the first and second conveyer screw of the first conveyer screw system, a speed of the first conveyer screw and a speed of the second conveyer screw are independently controllable from each other. In this way, a process speed in the cold and hot zone may be optimized.

[0030] Alternatively, the first conveyer screw system may comprise a single screw and wherein a space is formed within a portion of the single screw for forming the buffer space.

[0031] Optionally or additionally, the first conveyer screw system of the first vessel comprises a first hollow shaft forming a first tubular element for receiving a first heating means so as to generate radial heating from inside of the first vessel.

[0032] Advantageously, by providing a radial heating from the inside of the vessel to the outside of the vessel, the intra-material heat transfer efficiency within the plastic matrix in solid or molten states is enhanced. Advantageously, due to the radial heating from inside of the vessel, the entire conveyer screw system will heat up and the sticking of materials on the walls of the vessel is reduced.

[0033] Optionally or additionally, an inner screw is located within the first tubular element, and wherein the inner screw is configured for conveying the first heating means through the first tubular element, preferably wherein the inner screw is extending along a central axis of the hollow shaft. Preferably, the inner screw is a shaftless inner screw.

[0034] In this way, char, also named carbon black, resulting from the pyrolysis of the plastic waste may be used as a heating means for heating the first vessel from the inside. Indeed, the shaftless inner screw may be configured for conveying the char through the tubular element, preferably the char is conveyed from an entrance side of the tubular element where the char is received to an exit side of the tubular element where the char is outputted.

[0035] Preferably, the entrance side of the tubular element is located at the second end of the first vessel, i.e. at the outlet side of the first vessel. In this way, the char is transported in a direction opposite the direction of the flow of the feedstock, which is flowing from the first end to the second end of the first vessel. By doing so, an optimum heat transfer for heating the feedstock may be obtained over the entire length of the first vessel.

[0036] Advantageously, the carbon black heat is used to preheat the incoming feedstock material while it cools. In this way, a dual effect is obtained of heating feedstock material and, at the same time, cooling the carbon black. In this way energy efficiency is guaranteed.

[0037] The system for recycling a plastic feedstock according to the present disclosure may either be a single-vessel system or alternatively a system comprising a plurality of vessels coupled together, for example a system comprising a first and a second vessel wherein an output of the first vessel is coupled to an input of the second vessel. The first vessel may for example be a vessel for pre-treating the plastic feedstock, and wherein the first vessel comprises an output for outputting the pre-treated plastic feedstock, and wherein the system may further comprise a second vessel for pyrolyzing the pre-treated plastic feedstock. Such a system having a first and a second vessel comprises a connection element coupling the output of the first vessel with an input of the second vessel.

[0038] Further, the second vessel may comprise a second conveyer screw system configured for conveying the pre-treated plastic feedstock from a first end to a second end of the second vessel.

[0039] Optionally or additionally, the system may further comprise a char conveyer configured for conveying char outputted from the second vessel to the entrance side of the first tubular element of the first vessel.

[0040] Optionally, the second conveyer screw system may comprise a second hollow shaft forming a second tubular element for receiving a second heating means so as to generate radial heating from inside of the second vessel. In this way, also the second vessel for pyrolyzing the pre-treated plastic may be heated not only from the outside to the inside but also from the inside to the outside.

[0041] Advantageously, the hot gases, liquids or solids resulting from the pyrolysis reactor may be used as a heat source for heating the vessel from the inside. In this way, not only is the intra-heat transfer efficiency increased but also the energy efficiency is increased, as the energy required from external energy sources is reduced. This generally also results in a decrease of the overall CO2 emission.

[0042] Optionally or additionally, the first vessel comprises an inner radial wall radially delimiting the first vessel and an outer radial wall surrounding, or at least partly surrounding, and spaced from the inner radial wall so as to form a first annular condensation chamber surrounding or at least partly surrounding the first vessel. Further, the first annular condensation chamber comprises an inlet for receiving pyrolysis oil gas and an outlet for outputting oil resulting from condensation of the pyrolysis oil gas received.

[0043] For a single vessel system configuration, the first annular condensation chamber may receive the pyrolysis oil gas produced in the second part of the first vessel. For a two-vessel system comprising a first and a second vessel coupled to the first vessel, the first annular condensation chamber may receive the pyrolysis oil gas produced in the second vessel.

[0044] Optionally or additionally, a heat insulating jacket may be surrounding the first annular condensation chamber.

[0045] Advantageously, by providing a first condensation chamber located around the first reactor vessel and by supplying pyrolysis gas to the first condensation chamber, heat of the pyrolysis oil gas is recovered and the temperature in the first reactor vessel may be increased. In this way heat of pyrolysis gas is recovered in an efficient and economical manner.

[0046] Advantageously, oil gas may be condensed without the need of cumbersome cooling systems and processes.

[0047] Advantageously, by providing a condensation chamber surrounding part of the reactor vessel, the surface for condensation may be large, knowing that reactor vessels for pyrolysis of plastics may be more than 50 meters long and in some cases have a 2 meter or more diameter.

[0048] For a system comprising besides the first vessel a second vessel coupled to the first vessel, the inlet of the first annular condensation chamber may be configured for receiving pyrolysis oil gas produced in the second vessel. In these embodiments, the second vessel comprises a pyrolysis oil gas output for outputting pyrolysis oil gas that is coupled with the inlet of the first condensation chamber of the first vessel.

[0049] Preferably, the system further comprises a feedback device configured for suppling pyrolysis oil gas produced in the second reactor vessel to the inlet of the first annular condensation chamber. In embodiments, the feedback device comprises a first gas input coupled with the pyrolysis oil gas output of the second vessel so as to receive pyrolysis oil gas and a gas output coupled with the inlet of the first annular condensation chamber.

[0050] Advantageously, the feedback device may comprises a hydrogenation unit configured for hydrogenating the pyrolysis oil gas received from the second reactor vessel, and wherein the feedback device comprises a second gas input for receiving hydrogen.

[0051] Advantageously, the pyrolysis system may comprise a hydrogen generation unit for on-line production of hydrogen.

[0052] Optionally or additionally, the second vessel, or in case of a singlevessel system the second part of the first vessel, comprises an inner radial wall and an outer radial wall surrounding and spaced from the inner radial wall so as to form an annular heating chamber surrounding the second vessel, or the second part of the first vessel in case of a single-vessel system. Optionally, a further heat insulating jacket may be surrounding the annular heating chamber.

[0053] Typically, the annular heating chamber comprises an input for receiving a heating medium, preferably wherein the heating medium is a hot gas or a hot liquid. Hence, the annular heating chamber allows for heating up the second vessel or, in cases of a single-vessel system configuration, the second part of the first vessel.

[0054] Optionally or additionally, the system may further comprise a buffer hopper for supplying plastic waste to the first vessel and a plastic supply system comprising a conveyer screw for transporting plastic waste from a primary plastic supply input to the buffer hopper, and wherein the conveyer screw is located within an elongated tank.

[0055] Advantageously, with such a plastic supply system, a second condensation chamber may be formed. Indeed, the elongated tank may comprise a first radial wall and a second radial wall at least partly surrounding the first radial wall and spaced from the first radial wall so as to form a second annular condensation chamber surrounding at least part of the elongated tank. Optionally the second annular condensation chamber may be provided with a heat insulating jacket.

[0056] The first annular condensation chamber surrounding the first vessel further may comprises a gas outlet, and wherein the second annular condensation chamber around the elongated tank of the plastic supply system comprises a gas inlet coupled with the gas outlet of the first annular condensation chamber. In this way, the first and second condensation chamber are placed in series. The second annular condensation chamber generally may further comprise an oil and gas output.

[0057] In embodiments, the system may further comprise a separation tank and a hydrogen generation unit. The separation tank may be coupled to the oil and gas output of the second annular condensation chamber, and wherein the separation tank may be configured for separating noncondensable gases from oil. The hydrogen generation unit may be configured for receiving non-condensable gases from the separation tank and for outputting hydrogen gas. The hydrogen generation unit may be further configured for supplying hydrogen to the hydrogenation unit.

[0058] Optionally or additionally, the system may further comprise an oxygen removing device configured for removing oxygen from the plastic feedstock before the plastic feedstock is entering the first vessel.

[0059] Advantageously, with the oxygen removing device, a pyrolysis system can be used having a continuous feeding process, i.e. continuous pyrolysis. Indeed by using the oxygen removing device, air, containing oxygen, can be kept out while continuously feeding in new material.

[0060] Advantageously, with the oxygen removing device and / or in combination with the buffer space discussed above, the selectivity in the type and conditions of the materials fed into the reactor can be reduced. For instances larger pieces of material, e.g. plastic waste, can be fed into the pyrolysis reactor without the need to use shredding, grinding or milling as a pre-treatment for reducing the larger pieces into smaller particles, as is the case with present pyrolysis systems.

[0061] In embodiments, the oxygen removing device may comprise a transfer chamber having an input opening for receiving the feedstock and an output opening coupled to the input of the first vessel for discharging the plastic feedstock into the first vessel, and a rotor disposed within the transfer chamber and configured for dividing the transfer chamber into rotatable chamber sections. By rotation of the rotor each of the chamber sections is sequentially positionable into at least: -a first position for receiving feedstock through the input opening of the transfer chamber and thereby filling the chamber section with feedstock, -a second position wherein a wall portion of the transfer chamber is closing off the filled chamber section such that feedstock is no longer receivable in the chamber section and feedstock is also not dischargeable from the chamber section, and -a third position for discharging the filled chamber section through the output opening of the transfer chamber. The oxygen removing device further comprises a vacuum pump configured for pumping any of or a combination of air, water vapour and VOC gases from each chamber section when positioned in the second position.

[0062] Advantageously, by using chamber sections that can be rotated to different positions, and by providing a vacuum pump, any of air, water vapour or VOC gases can be removed from the feedstock when the chamber section is located in a position wherein no feedstock is receivable or can be discharged. In this way, oxygen, e.g. present in the air, is being removed from the feedstock before supplying the feedstock to the pyrolysis reactor. VOC gases are known as volatile organic compound gases.

[0063] Advantageously, with the oxygen removing device according to the present disclosure a cost effective way is provided for removing oxygen from a pyrolysis feedstock. Advantageously, with the oxygen removing device according to the present disclosure a more ecological system is offered as opposed to systems introducing inert gases, blowing in smoke or removing air without sectioning chambers

[0064] When the word dimension is used throughout the description, for instance in dimension of feedstock or the dimension of a piece of feedstock material, it has to be construed as being the maximum dimension that can be measured between two extremities of a piece of feedstock material.

[0065] Short description of the drawings

[0066] These and further aspects of the present disclosure will be explained in greater detail by way of example and with reference to the accompanying drawings in which:

[0067] Fig.l schematically illustrates a cross sectional view of a portion of an embodiment of a pyrolysis plastic waste recycling system according to the present disclosure, wherein a buffer space is created between a first and second part of a reaction vessel,

[0068] Fig.2 schematically illustrates a cross sectional view of an embodiment of a pyrolysis plastic waste recycling system according to the present disclosure, comprising a first and a second vessel and wherein a buffer space is created between a first and second part of the first vessel,

[0069] Fig.3 schematically illustrates a cross sectional view of an example of an embodiment of a pyrolysis plastic waste recycling system comprising a vessel with a buffer space and wherein an oxygen removing device is provided for removing oxygen from the pyrolysis feedstock before entering the vessel,

[0070] Fig.4 schematically illustrates a cross sectional view of the pyrolysis plastic waste recycling system of Fig.3, wherein additionally a feedstock supply system having a primary conveyer screw is provided for transporting feedstock from a primary feedstock input to the buffer feedstock hopper,

[0071] Fig.5 schematically illustrates a cross sectional view of an oxygen removing device for removing oxygen from a pyrolysis feedstock according to the present disclosure,

[0072] Fig.6 schematically illustrates a cross-sectional view of a hopper comprising an oxygen removing device according to the present disclosure.

[0073] Fig.7 schematically illustrates a cross-sectional view of an example of an embodiment of a vessel according to the present invention comprising a conveyer screw having a hollow shaft,

[0074] Fig.8 is perspective view of the vessel shown on Fig.7, schematically illustrating a conveyer screw having a hollow shaft wherein heating means inside the hollow shaft provide for radial heat generation,

[0075] Fig.9 schematically illustrates a cross-sectional view of a further example of an embodiment of a vessel according to the present invention comprising a conveyer screw having a hollow shaft and wherein a shaftless conveyer screw is located within the hollow shaft,

[0076] Fig.10 is a perspective view of the vessel shown on Fig.9, schematically illustrating the transport of char through the hollow shaft using the shaftless conveyer screw,

[0077] Fig.11 is a cross-sectional view of an embodiment of a pyrolysis system according to the present invention comprising a first vessel for pretreatment of plastic waste and a second vessel for pyrolyzing the pretreated plastic waste, and wherein the second vessel comprises a conveyer screw having a hollow shaft for receiving heating means such as a hot fluid,

[0078] Fig.12 is a cross-sectional view of an embodiment of a pyrolysis system according to the present invention comprising a first vessel for pretreatment of the plastic waste and a second vessel for pyrolyzing the pretreated plastic waste, and wherein the first vessel comprises a conveyer screw having a hollow shaft and wherein an inner screw is located within the hollow shaft for conveying char through the hollow shaft, and wherein a char conveyer is configured for conveying hot char outputted from the second vessel to the entrance side of the hollow shaft,

[0079] Fig.13 schematically illustrates a cross-section, taken in a first plane, of an example of an embodiment of a pyrolysis system according to the present disclosure comprising an annular condensation chamber surrounding or at least partly surrounding a reactor vessel,

[0080] Fig.14 is cross-section of the pyrolysis reactor shown on Fig.13, wherein the cross-section is taken in a second plane, perpendicular to the first plane,

[0081] Fig.15 schematically illustrates a cross-section, taken in a first plane, of an example of a further embodiment of a pyrolysis system according to the present disclosure comprising a first and a second vessel coupled together, and wherein an annular condensation chamber is provided to each of the two vessels,

[0082] Fig.16 is a cross-sectional view, illustrating an example of an embodiment of a pyrolysis system according to the present disclosure having a single vessel and wherein oil is recovered from pyrolysis gas by making use of an annular condensation chamber around the vessel,

[0083] Fig.17 is a cross-sectional view, illustrating a further example of an embodiment of a pyrolysis system according to the present disclosure having a first and a second vessel and wherein oil is recovered from pyrolysis gas by making use of an annular condensation chamber around the first vessel.

[0084] The drawings of the figures are neither drawn to scale nor proportioned. Generally, identical components are denoted by the same reference numerals in the figures. Detailed description of embodiments

[0085] The present disclosure will be described in terms of specific embodiments, which are illustrative of the disclosure and not to be construed as limiting. It will be appreciated by persons skilled in the art that the present disclosure is not limited by what has been particularly shown and / or described and that alternatives or modified embodiments could be developed in the light of the overall teaching of this disclosure. The drawings described are only schematic and are non-limiting.

[0086] Use of the verb "to comprise", as well as the respective conjugations, does not exclude the presence of elements other than those stated. Use of the article "a", "an" or "the" preceding an element does not exclude the presence of a plurality of such elements.

[0087] Furthermore, the terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the disclosure described herein are capable of operation in other sequences than described or illustrated herein.

[0088] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiments is included in one or more embodiment of the present disclosure. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one ordinary skill in the art from this disclosure, in one or more embodiments. Plastic recycling system, general

[0089] Typically, a pyrolysis system for recycling plastic feedstock comprises an input for receiving the plastic feedstock and an outlet for outputting any of or a combination of exhaust gases, oil gas, liquid fuels, and char resulting from a break-down of the feedstock due to a pyrolysis process.

[0090] The feedstock for the pyrolysis reactor has to be construed as pieces of solid material that need to undergo a pyrolysis treatment. The pieces of material can for example be solid pieces of plastic material, more specifically pieces of plastic waste and / or rubber waste, e.g. originating from used tyres.

[0091] With reference to Figures 1 to 4, examples of embodiments of a pyrolysis plastic waste recycling system 100 according to the present disclosure are shown.

[0092] The system 100 for recycling a plastic feedstock 10 by pyrolysis comprising at least a first vessel 50 which has an input 32 for receiving the plastic feedstock 10 and a first conveyer screw system 31 configured for conveying the received plastic feedstock from a first end 50a to a second end 50b of the first vessel 50.

[0093] The vessel may be also be named tank, and both words are considered synonym. Throughout the disclosure, the vessel or tank may also be named reactor vessel or reactor tank. Especially for embodiments wherein the system only comprises a single vessel, when the word reactor is used, it may also refer to the reactor vessel. A vessel or tank is to be interpreted as a device having a housing which, in embodiments, may have an overall shape of a tube or a cylinder. The vessel 50 may comprise a radial wall 51 extending axially along a central axis Y of the vessel from a first end 50a of the tank to a second end 50b of the tank, opposite the first end. As schematically illustrated on Fig.l to Fig.4, the first vessel 50 comprises a first part 30a and a second part 30b, and wherein the first part is separated by the second part by a buffer space 34.

[0094] The buffer space is a volume or area wherein plastic feedstock can be accumulated and / or mixed up. When the system is in operation, the buffer space is filled up with plastic feedstock. Indeed, this buffer space 34 allows for building up a buffer of plastic feedstock inside the first vessel and / or to enable plastic feedstock of different sizes or melt temperatures to be mixed up before entering the second part.

[0095] Generally, the first part 30a and the second part 30b of the first vessel correspond to respectively a first operational zone and a second operational zone of the first vessel, and wherein the system is configured for operating within a first temperature range in the first operational zone and within a second temperature range in the second zone.

[0096] The temperature in the first operational zone is lower than the temperature in the second operational zone. For example, when the system is in operation, the first operational zone may have a temperature in a range between -25°C to 200°C, preferably between -10°C to 150°C, and the second operational zone may have a temperature in a range between 150°C to 650°C, preferably 250°C to 650°C, more preferably wherein the second zone has a temperature in a range between 350°C and 550°C. Hence in the first zone, the temperature is generally too low for starting a pyrolysis reaction.

[0097] In embodiments, when the system is in operation, the temperature in the first operational zone is in a range between -10°C and 150°C and the temperature in the second operational zone is in a range between 150°C and 650°C.

[0098] The first and second operational zone may also be referred to as the cold and hot zone, respectively. In the second part of the first vessel where the temperature is higher, the pieces of plastic 10 may be transformed from solids 10a into liquid 10b and gases, as schematically illustrated on Fig.l to Fig.4.

[0099] In embodiments, to realize the buffer space 34 the first conveyer screw system 31 is provided with two screws. In the example shown on Fig.l to Fig.4, the first part 30a of the first vessel 50 accommodates a first conveyor screw 31a while the second part 30b accommodates a second conveyor screw 31b. The first conveyer screw is extending from a begin side to an end side of the first conveyer screw, and the second conveyer screw is extending from a begin side to an end side of the second conveyer screw. As schematically shown on the figures, the first and second screw are oriented in a same direction and the begin side of the second screw is separated from an end side of the first screw so as to create a space between the first and second conveyer screw. This space between the first and second conveyer screw is forming the buffer space 34 mentioned above.

[0100] In embodiments, the buffer space 34 may also be achieved by using a single screw. However, in that case, the cold and hot zones speeds cannot be regulated independently from each other as is the case for an embodiment wherein the first conveyer screw system 31 is provided with two screws that may be controlled independently from each other.

[0101] In embodiments, the first conveyer system 31 may be provided with a single screw and wherein within a portion of the single screw, e.g. a central portion of the single screw, the buffer space 34 is formed. For example, within the portion of the single screw one or more blades of the single screw may be omitted so as to form the buffer space within the portion of the single screw.

[0102] In embodiments, the first conveyer screw 31a is configured for receiving feedstock through the reactor input 32 of the first vessel 50. The reactor input is generally located at the first side 50a of the first vessel 50. Generally, the first 31a and / or second 31b conveyer screw are profiled conveyer screws adapted to transport large pieces of feedstock material. In this way, the risk of blocking the screw when in operation, is reduced.

[0103] As mentioned above, when the system is in operation, the buffer space 34 is filled up with feedstock so as to enable feedstock of different sizes and / or melting temperatures to be mixed up before entering the second zone via the second conveyer screw 31b. In addition, by creating such a material buffer in the buffer space, by compressing the feedstock material, a seal is formed within the reactor which blocks gases produced in the second part of the reactor to flow to the first part of the reactor. It also blocks gases from the first part of the reactor from entering the second part of the reactor and hence preventing oxygen leaks to the hot zone and avoiding combustion. Additionally, it enables the possibility to independently controlling the speed of the different zones that results to higher operational efficiency.

[0104] In embodiments, as schematically shown on Fig.3 and Fig.4, the system 100 may further be provided with an oxygen removing device 1 configured to remove oxygen from the feedstock 10 before it enters the first vessel 50. The oxygen removing device is further discussed in more detail here below.

[0105] The pyrolysis system for recycling plastic comprises at least one vessel 50 but may also comprise more than one vessel. For example in Fig.2 an embodiment is shown comprising a first 50 and a second 90 vessel.

[0106] In the embodiment shown on Fig.2, the first vessel 50 is extending axially along a first central axis Y 1 and the second vessel 90 is extending axially along a second central axis Y2, preferably the first and second central axis are parallel.

[0107] In these embodiments comprising for instances two vessels 50 and 90, the first vessel 50 can be considered as a vessel for pre-treating or preconditioning the plastic feedstock, and the first vessel 50 comprises an output 33 for outputting the pre-treated plastic feedstock. A connection element 93, also named coupling device, is provided for coupling the output 33 of the first vessel 50 with an input of the second vessel 90. The second vessel 90 is a vessel configured for pyrolyzing the pre-treated plastic feedstock received from the first vessel.

[0108] The white arrows 85 on Fig.2 indicate a flow direction of the feedstock from the first vessel to the second vessel.

[0109] For a two vessel system, the second vessel 90 typically comprises a second conveyer screw system 58 configured for conveying the pre-treated plastic feedstock from a first end 90a to a second end 90b of the second vessel 90.

[0110] Different heating devices may be used for heating the first and / or second vessel of the pyrolysis system, as will be discussed more in detail below.

[0111] The pyrolysis plastic waste recycling system according to the present disclosure may be a continuous-type system wherein, when the system is in operation, plastic feedstock 10 is continuously fed into the first vessel 50.

[0112] For a continuous-type of system a feedstock supply system is generally provided for continuously providing feedstock. With reference to Fig. 4., in embodiments, the plastic recycling system 100 comprises a feedstock supply system 35 having a primary conveyer screw 36 configured for transporting feedstock 10 from a primary feedstock input 25 to a buffer feedstock hopper 20, and wherein the buffer feedstock hopper 20 comprises a funnel portion receiving the feedstock supplied through the primary conveyer screw 36 and a neck portion. As schematically illustrated on Fig.4, an output side of the funnel portion is coupled to an input side of the neck portion. In this example, an oxygen removing device 1, discussed in more detail here below, is forming the neck portion of the buffer feedstock hopper 20 and the input side of the neck portion corresponds to the input opening of the oxygen removing device 1.

[0113] Generally, the primary conveyer screw 36 of the feedstock supply system 35 may be profiled, and wherein the profile of the primary conveyer screw 36 is adapted to receive and transport large pieces of feedstock material. Generally, the primary conveyer screw 36 is configured for transporting pieces of feedstock having dimensions up to at least 5 mm, preferably up to at least 5 cm, more preferably up to at least 12 cm.

[0114] The conveyer screw system 31, 58 of the first 50 and / or second 90 vessel are rotatable around a rotation axis that is parallel with the central axis of the vessel. Preferably, the rotation axis is coinciding with the central axis Y of the vessel.

[0115] Typically, as schematically illustrated on Fig.12, the vessel 50 comprises first drive means 97 for driving the rotation of the first conveyer screw system 31. In embodiments, the drive means 97 comprise a motor and a transmission gear.

[0116] Similarly, for embodiments comprising a second vessel 90, as shown on Fig.11, the second vessel 90 comprises second drive means 97b for driving the rotation of the second conveyer system 58.

[0117] For a two-vessel system, various configurations for what concerns the relative orientation of the two vessels may be considered. In the embodiments shown on for example Fig.2, Fig.11, Fig.12, Fig.15 and Fig.17, the first vessel 50 is elongating along a first central axis Y 1 and the second vessel is extending along a second central axis Y2. In embodiments the first Y1 and second Y2 central axes may be parallel.

[0118] In embodiments the first Y 1 and / or second Y2 central axes may be parallel with a floor level, e.g. a horizontal floor level. In other embodiments, the first and / or second central axis may be perpendicular to the floor level.

[0119] In embodiments wherein the first Y1 and second Y2 central axes are parallel with a floor level, e.g. a horizontal floor level, the first Y1 and second Y2 central axis may be located respectively at a first and a second height with respect to the floor level and the first height may be higher than the second height. In other words, the first part of the reactor 30a, e.g. the first vessel 50, may be located above the second part 30b, e.g. the second vessel 90.

[0120] In further embodiments, the second central axis Y2 may be perpendicular to the first central axis Yl.

[0121] Although embodiments of a single-vessel type and a two-vessel type are discussed, the pyrolysis system is not limited to one or two reactor vessels. In embodiments, a pyrolysis system may comprise a plurality of first reactor vessels for forming a cold zone for pre-conditioning the plastic waste and a plurality of second reactor vessels for forming a hot zone for pyrolyzing plastic waste.

[0122] Oxygen removing device

[0123] With reference to Fig.5, an oxygen removing device 1 for removing oxygen from a pyrolysis feedstock 10 according to the present disclosure is shown. The oxygen removing device 1 comprises a transfer chamber 2 having an input opening 4 for receiving the feedstock and an output opening 5 for discharging the feedstock into a vessel of the pyrolysis system.

[0124] As discussed above, the feedstock is discharged in a pyrolysis vessel, and in embodiments comprising more than one vessel, e.g. a first and a second vessel, the first vessel may be a vessel for conditioning or pre-conditioning the feedstock before the feedstock enters in a zone where the temperature is higher.

[0125] As further schematically illustrated on Fig.5, the oxygen removing device comprises a rotor 3 disposed within the transfer chamber 2 and configured for dividing the transfer chamber into rotatable chamber sections 6a, 6b, 6c, 6d. By rotation of the rotor 3, each of the chamber sections 6a, 6b, 6c, 6d is sequentially positionable into at least a first, a second and a third position.

[0126] The first position is a position for receiving feedstock through the input opening 4 of the transfer chamber and thereby filling the chamber section with feedstock. The second position is a position wherein a wall portion of the transfer chamber is closing off the filled chamber section such that feedstock is no longer receivable in the chamber section and feedstock is also not dischargeable from the chamber section. In other words, when in the second position, the materials of the feedstock are trapped into the chamber section. The third position is a position for discharging the filled chamber section through the output opening 5 of the transfer chamber.

[0127] The oxygen removing device further comprises a vacuum pump, not shown on Fig.5, that is configured for pumping any of air, water vapour or VOC gases from each chamber section when positioned in the second position. In Fig.5, a pump connection 7 is schematically shown for coupling the vacuum pump to the transfer chamber.

[0128] In embodiments, the feedstock is for example plastic waste comprising pieces of different sizes.

[0129] The oxygen removing devices allows to receive larger pieces of plastics, i.e it is not necessary to first reduce the plastic pieces in smaller pieces. The pieces of feedstock receivable by the oxygen removing device have dimensions up to at least 5 mm, preferably up to at least 5 cm, more preferably up to at least 12 cm.

[0130] In embodiments, the transfer chamber 2 may be made of steel.

[0131] In embodiments, the oxygen removing device 1 further comprises a seal 8 configured such that each chamber section when positioned in the second position is sealingly closed off from an adjacent chamber section located in the first position and / or an adjacent chamber section located in the third position. In this way, no gases are sucked from the pyrolysis vessel while the air from the feedstock is being removed. In embodiments, the seal 8 is a flexible seal configured to allow the rotor to rotate freely for moving the chamber sections from one position to another position.

[0132] The seal 8 may for example be a flexible flap, preferably an elastomeric flexible flap.

[0133] In embodiments, the seal 8 may be attached to the inner wall of the transfer chamber.

[0134] In the example shown on Fig.5, the oxygen removing device comprises four chamber sections. In other embodiments, three or more chamber sections may be provided.

[0135] In embodiments, the rotor 3 comprises a rotation axis and a plurality of blades connected to the rotation axis, and wherein each chamber section is delimited by two adjacent blades of the plurality of blades.

[0136] Generally, the rotor comprises two or more blades.

[0137] In embodiments, the rotor comprises four blades defining four adjacent chamber sections.

[0138] In the embodiment shown on Fig.5, the oxygen removing device may be positioned in four positions. The fourth position is located between the third and first position, and wherein when in the fourth position a further wall portion of the transfer chamber is closing off the chamber section such that no feedstock can be received or discharged from the chamber section when in the fourth position.

[0139] The rotation of the rotor is generally automated using a motor. The oxygen removing device may also comprise a controller for controlling rotation of the rotor and controlling the vacuum pump.

[0140] As schematically shown on Fig.5, the transfer chamber comprises a pump opening 7 coupled with a suction side of the vacuum pump and wherein the pump opening is configured such that for a chamber section being positioned in the second position air and / or water vapour is pumped from the chamber section. With reference to Fig.6, a cross-sectional view of a feed hopper 20 for supplying feedstock to a pyrolysis reactor is shown. The feed hopper 20 comprises an oxygen removing device 1 according to the present disclosure.

[0141] Generally, the feed hopper comprises a funnel portion 20a and a neck portion 20b, and wherein an output side of the funnel portion is coupled to an input side of the neck portion. As schematically shown on Fig.6, in this embodiment, the oxygen removing device is forming the neck portion and the input side of the neck portion corresponds to the input opening of the oxygen removing device.

[0142] With reference to Fig.3 and Fig.4, an example of a pyrolysis plastic waste recycling system 100 comprising a pyrolysis reactor vessel 50 and an oxygen removing device 1 is shown. The output opening 5 of the oxygen removing device is coupled to a reactor input of the reactor vessel 50.

[0143] Sieve and solid separator

[0144] A further innovation relates to a sieve and solid separator which may be used with the system for recycling plastic feedstock.

[0145] In embodiments, the plastic waste recycling system 100, as shown on Fig.3 and Fig.4, further comprises, a residue discharge screw 39b and a sieve and solid separator 37 configured for separating char from other solids. The sieve and solid separator 37 is coupled to an output 33 of the reactor vessel 50.

[0146] Typically, the sieve and solid separator 37 comprises a sieve 39 having perforations configured to separate char from other solids having dimensions larger than the dimensions of char.

[0147] In embodiments, when the system 100 is in operation, the residue discharge screw 39b, when in operation, is configured to generate a pressure above the sieve 39 so as to enhance the separation performance of the sieve and solid separator 37. The large pieces above the mesh diameter of the sieve 39 are trapped and extracted separately from the char which is finer in nature and falls through the sieve. On Fig.3 and Fig.4, the sieve and solid separator 37 is shown to comprise a first particle output 38a and a second particle output 38b. The second particle output 38b is for particles, e.g. char, having dimensions smaller than the mesh dimensions of the sieve and the first particle output 38a is for particles having dimensions larger than the mesh dimensions of the sieve.

[0148] In embodiments, the pyrolysis system may comprise a vibrator coupled to the sieve and solid separator 37 and configured for enhancing the separation performance of the sieve and solid separator at high temperature.

[0149] Advantageously, the pyrolysis system as shown on Fig.3 and Fig.4, enables the feeding in of large size plastic and rubbers especially containing metal. The sieve and solid separator 37 enables the separation and purification of carbon black and the recovery of other solids such as for example metals and inorganic additives.

[0150] Heatins through a hollow shaft of a screw conveyer

[0151] In embodiments, as schematically illustrated on Fig.7 and Fig.8, the conveyer screw system 31 of the first vessel 50 comprises a first hollow shaft 52 forming a first tubular element 52 for receiving a first heating means 60 so as to generate radial heating from inside of the first vessel 50.

[0152] As schematically shown on Fig. 11, for embodiments comprising a first 50 and a second vessel 90, the second vessel 90 may comprise a second hollow shaft 52b forming a second tubular element 52b for receiving a second heating means 60b.

[0153] The tubular element, i.e. the hollow shaft, that is located inside the vessel is extending axially along the central axis Y from the first end to the second end of the vessel. The tubular element and the hollow shaft may be considered synonyms and these words are further interchangeably used here below when further discussing embodiments comprising a conveyer screw with hollow shaft.

[0154] In embodiments, the tubular element 52, 52b forming a shaft may be considered as having a shape of a tube.

[0155] Generally, the tubular element 52, 52b is radially delimited by a circumferential surface, i.e. a radial wall. Due to the radial heating from the inside of the tubular element, the circumferential surface is forming a heat transfer surface for transferring heat to the feedstock material 10 undergoing a pre-treatment or undergoing a pyrolysis reaction.

[0156] As discussed above the first conveyer screw system 31 of the first vessel 50 may comprise a first 31a and a second 31b conveyer screw. Typically, the conveyer screws comprises a plurality of blades 59 attached to the shaft 52 of the conveyer screw system.

[0157] In embodiments, the shaft of the conveyer screw system 31 may be a common shaft for both the first 31a and second 31b conveyer screw.

[0158] In embodiments wherein the tubular element 52 corresponds to the hollow shaft of the conveyer screw system, as for instance shown on Fig.7 and Fig.8, when rotating the conveyer screw system, also the hollow shaft 52 of the conveyer screw system is rotating.

[0159] In embodiments, the heating means 60 in the hollow shaft comprises an electrical heating element or any other suitable heating element, i.e. an active heating element, located inside the tubular element. Heating means may for example be a hot gas or liquid.

[0160] Advantageously, in embodiments, the heating means may also be hot reaction products resulting from the pyrolysis reaction, such as pyrolysis gas or char such that heat resulting from the pyrolysis reaction can be recovered, as will be discussed in more detail here below. In embodiments, as schematically illustrated on Fig.9 and Fig.10, the first vessel 50 further comprises an inner screw 55 extending along the central axis Y, and wherein the inner screw 55 is located within the first tubular element 52. In other words, the inner screw 55 is a screw installed within the hollow shaft 52 of the first conveyer screw system 31.

[0161] Advantageously, the inner screw may be configured for conveying the first heating means 60 through the first tubular element 52.

[0162] In embodiments, char resulting from the pyrolysis of the plastic waste is used as a heating means 60 for heating the vessel 50 from the inside towards the outside.

[0163] As schematically illustrated on Fig.10 and Fig.12, the inner screw 55 is configured for conveying the char 15 through the tubular element 52 inside the first vessel 50.

[0164] The inner screw 55 is rotatable around a rotation axis parallel with the central axis Y of the vessel, preferably the rotation axis of the inner screw is coinciding with the central axis Y of the vessel.

[0165] Generally, in embodiments wherein the vessel comprises an inner screw 55 the vessel further comprises second drive means 98 for driving a rotation of the inner screw 55, as schematically illustrated on Fig.12.

[0166] In embodiments, the conveyer screw system 31 is configured for rotating in a first rotational direction and the inner screw 55 is configured for rotating in a second rotational direction, opposite from the first rotational direction. For example the conveyer screw system 31 may rotate clockwise and the inner screw 55 may rotate anti-clockwise or vice-versa.

[0167] Preferably, the inner screw 55 is a shaftless inner screw. A shaftless screw is also known as a helical screw.

[0168] Advantageously, the open core of the shaftless inner screw 55 provides easy passage of big particles and lumps and hence is able to convey them without blockage. If an inner screw with a shaft would be used, there might be an issue of blocking of the screw if the char particles are too large or contain large particle impurities like stones, metal, or other impurity materials.

[0169] In embodiments, as schematically illustrated on Fig.12, the char 15 enters the tubular element 52, i.e. the hollow shaft of the first conveyer screw system 31, from an entrance side 87 of the tubular element and exits the tubular element at an exit side 88 of the tubular element, opposite the entrance side. In other words, the inner screw 55 is configured for conveying the char 15 through the tubular element 52 from the entrance side of the tubular element to the exit side of the tubular element.

[0170] The entrance side 87 of the tubular element is defined as the side of the tubular element where the char 15 is received and the exit side of the tubular element is defined as the side where the char 15 is outputted.

[0171] As schematically illustrated for the embodiment shown on Fig.12, the entrance side 87 of the tubular element receiving the char is located at the second end 50b of the vessel 50, i.e. at the outlet side of the vessel. In other words, the char, when being transported from the entrance side 87 to the exit side 88 of the tubular element, is moving in a direction opposite to the flow direction of the feedstock that is flowing from the first end 50a of the vessel to the second end 50b of the vessel 50. In Fig.12, the flow of the feedstock is indicated with a white arrow 85.

[0172] In embodiments, the entrance side of the tubular element receiving the char is located at the outlet side of the first vessel, i.e. the char is introduced in the vessel from the second zone that is at a higher temperature compared to first zone, as discussed above. As the char is conveyed, it loses its heat to the materials in the reactor vessel which are conveyed from the cold to the hot zone of the reactor vessel. This evidently cools the char while heating up the incoming material. Depending on the ambient temperature, the incoming material could be at temperature range -25°C to +45°C. Employing the present technique using the shaftless inner screw 55 for conveying the char through the hollow shaft 52 of the conveyer screw, could raise material temperature in the first zone up to at least 100°C, preferably up to at least 150°C, depending on the amount of char produced by the waste being pyrolyzed.

[0173] In embodiments, as schematically illustrated on Fig.10, the shaftless inner screw 55 comprises a first shaftless screw part 55a extending along the central axis Y from a begin side to an end side of the first shaftless screw part and a second shaftless screw part 55b extending along the central axis Y from a begin side to an end side of the second shaftless screw part.

[0174] As further schematically illustrated on Fig.10, the begin side of the second shaftless screw part 55b is separated from and facing the end side of the first shaftless screw part 55a such that a char buffer space 18 is created within the tubular element 52 between the first 55a and second 55b shaftless screw part.

[0175] When the vessel is in operation, the char buffer space 18 may be filled up with char.

[0176] The char buffer space 18 ensures a continuous flow and it helps to reduce the length of the shaftless screw and thereby reduce power and slagging. It also facilitates the maintenance because the length of the screw is shorter and no big spaces are required to replace the screw or service the screw.

[0177] In embodiments wherein the inner screw 55 comprises two shaftless parts, the system may comprise one or more motors for driving a rotation of the first and second shaftless screw part.

[0178] In embodiments, a single motor for driving a rotation of the conveyer screw system 31 and for driving a rotation of the shaftless inner screw 55 may be provided.

[0179] In embodiments, for providing heating means 60 into the tubular element 52, i.e. into the hollow shaft of the conveyer screw system, a hot gas or a hot liquid is supplied into the tubular element. In other words, the hot gas or hot liquid are forming the heating means 60 for generating radial heat from inside of the vessel.

[0180] In embodiments, the hot gas supplied through the hollow shaft is hot air or exhaust hot smoke, e.g. flue gas.

[0181] In embodiments, an entrance side of the tubular element, i.e. the hollow shaft, is configured for receiving any of or a combination of the exhaust gases, oil gas, liquid fuels, or char, and wherein the exhaust gases, oil gas, liquid fuels or char are forming the heating means 60. In this way, the exhaust heat is recovered.

[0182] In Fig.8, the heating 66 from outside to the inside of the vessel 50 using a classical external heating device 80 is schematically illustrated with arrows 66, while the radial heating 65 from the inside to the outside using the heating means 60, e.g. flue gas, located inside the hollow shaft 52 is schematically illustrated with further arrows 65.

[0183] In embodiments, as illustrated on Fig.11, the entrance side 87b of the hollow shaft 52b for receiving hot gas or hot liquid is located at the second end 90b of the second vessel 90 and an exit side 88b of the hollow shaft 52b for outputting the hot gas or hot liquid is located at the first end 90a of the second vessel 90. In this way, when the system is in operation, the hot gas or hot liquid is flowing in an opposite direction of a flow direction of the feedstock 10. Indeed, the second conveyer screw system 58 in the second vessel 90 is conveying the feedstock 10 in a direction from the first end 90a to the second end 90b of the second vessel. In Fig.11, an embodiment of a vessel 90 is shown wherein the flow direction of the hot gas in the hollow shaft 52b inside the vessel 90 is indicated with a black arrow 86 and the flow direction of the feedstock 10 inside the vessel 90 is indicated with a white arrow 85.

[0184] Generally, the system additionally comprises an external heating device 80 configured for heating a circumferential outer side or at least a portion of a circumferential outer side of the vessel 50 so as to generate radiation heat 66 from the outside to the inside of the vessel, as schematically illustrated on Fig.8 and Fig.10.

[0185] Different external heating techniques for heating the vessel 50 from the outside of the vessel may be applied such as the use of hot air, induction heating, filament heating, infrared heating or any other heating means suitable for heating the vessel 50 from the outside.

[0186] Hence, with the system according to the present disclosure, heating means may be provided to heat up the reactor vessel both from the inside to outside as well as from outside to the inside. This combined heating ensures that the feedstock in the reactor will be heated both from the inside direction and from the outside direction, reducing the heating surface area / mass or otherwise increasing heat dispersion and transfer efficiency.

[0187] Advantageously, with the vessels according to the present disclosure a reduced heating mass is obtained due to the efficient heating of the feedstock material by using a combination of heating from inside to outside and from outside to inside of the vessel.

[0188] Char heat recovery

[0189] The embodiment of the system 100 for recycling a plastic feedstock shown in Fig.12 is now further discussed. The system 100 shown on Fig.12 comprises a first vessel 50 for pretreatment of the plastic waste, and a second vessel 90 for pyrolyzing the pre-treated plastic waste.

[0190] The system comprises a connection element 93 connecting an output of the first vessel 50 with an input of the second vessel 90.

[0191] As schematically illustrated on Fig.12, the first vessel 50 comprises a conveyer screw system 31 for conveying the feedstock 10 in a direction along the central axis Y1 from a first end 50a of the vessel to a second end 50b of the vessel. The white arrows 85 on Fig.12 schematically illustrates a flow direction of the feedstock. The conveyer screw system 31 comprises a hollow shaft 52, and wherein an inner screw 55 is located inside the hollow shaft, as discussed above.

[0192] The vessel 50 further comprises first drive means 97 for rotating the conveyer screw system 31 and second drive means 98 for driving the inner screw 55. In this example, the conveyer screw system 31 comprises a plurality of blades 59 attached to a tubular element 52 that is forming the hollow shaft for the conveyer screw system 31. In this example, the inner screw is a shaftless inner screw.

[0193] In embodiments, as discussed above, wherein the inner screw 55 comprises a first screw part 55a and a second screw part 55b, separate drive means may be provided for the first screw part 55a and the second screw part 55b. In these embodiments, second and third drive means are provided for driving respectively the first and second screw part of the inner screw. Preferably, wherein the drive means of the screw parts each comprises a motor.

[0194] In embodiments, as illustrated on Fig.12, the system 100 comprises a char conveyer 95 configured for conveying char 15 outputted from the second vessel 90 to the entrance side of the tubular element 52 of the first vessel 50. As mentioned above, the entrance side 87 of the tubular element is the side receiving the char, and for the embodiment shown on Fig.12, the entrance side 87 is located at the second end 50b of the first vessel 50, i.e. the outlet side of the first vessel.

[0195] The char outputted from the second vessel is hot and hence the hot char is forming heating means 60 for heating the first vessel from the inside of the vessel by conveying the hot char through the tubular element using the inner screw 55. As mentioned above, the tubular element corresponds to the hollow shaft of the conveyer screw system 31.

[0196] In embodiments, the char conveyer 95 comprises a char conveying screw 96 for transporting the char 15. In some embodiments, as schematically illustrated on Fig.12, a char buffer 17 may optionally be provided to buffer the char received from the second vessel 90. The char buffer may comprise a sieve. In other embodiments, no char buffer is provided.

[0197] In the embodiment shown on Fig.12, the char conveyer 95 comprises three char conveyer parts 95a, 95b and 95c. The first conveyer part 95a is conveying the char from the output of the second vessel 90 to a char buffer 17, the second conveyer part 95b is transporting the char in a direction parallel with the central axis Y2 of the second vessel 90 and the third conveyer part 95c is transporting the char in a direction perpendicular to the central axis Y2 towards the second end 50b of the first vessel 50. Each of the conveyer parts 95a, 95b, 95c may comprise a conveyer screw 96 and each conveyer screw may be provided with a motor to drive the rotation of the screw.

[0198] In the embodiment shown on Fig.12, the dotted arrows 89 indicate the path followed by the char from the output of the second vessel 90 to the entrance 87 of the hollow shaft located in the first vessel 50.

[0199] In embodiments, when the char 15 has passed through the hollow shaft of the first vessel 50, the char is outputted at the exit side 88 of the hollow shaft 52 and may further be collected in a char storage unit 19, as schematically illustrated on Fig.12. The char storage unit 19, as illustrated on Fig.12, may be located near the first end 50a of the first vessel 50, i.e. at the inlet side of the first vessel 50.

[0200] In embodiments, as discussed above, the system may further comprise a buffer hopper 20 configured for supplying plastic waste to the first vessel, and optionally further comprise a primary conveyer 70 comprising a primary conveyer screw 72 for transporting plastic waste from a primary plastic supply input 71 to the buffer hopper 20. The primary conveyer screw 72 is generally located within an elongated container 75, which may be a tube. Condensation, of pyrolysis gas

[0201] With reference to Fig.13 and Fig.15 to Fig.17, illustrating a system 100 for recycling a plastic feedstock 10 comprising at least a first vessel 50, further innovative features of the system, optionally or in addition to the features already discussed above according to the present disclosure are further discussed.

[0202] In embodiments, as schematically illustrated on the Figures 13 to 17, the first vessel 50 comprises an inner wall 51a radially delimiting the first vessel and an outer radial wall 51b surrounding, or at least partly surrounding, and spaced from the inner radial wall 51a so as to form a first annular condensation chamber 54 surrounding or at least partly surrounding the first vessel 50.

[0203] Generally, a heat insulating jacket 67 is surrounding the first annular condensation chamber 54. In this way, escape of heat through the external walls of the first reactor part is reduced.

[0204] The first annular condensation chamber 54 comprises an inlet 56 for receiving pyrolysis oil gas produced by the system 100. For instance pyrolysis oil gas produced in the second vessel 90 of a two-vessel system configuration. The annular condensation chamber 54 also comprises an outlet 57 for outputting oil resulting from condensation of the pyrolysis oil gas received.

[0205] When the system 100 is in operation, heat exchange between the oil gas and the incoming plastic waste materials occur, such that the incoming material, i.e. plastic waste, is being heated up and the oil gas is in the first condensation chamber 54 being cooled, hence condensing within the first condensation chamber 54 into oil.

[0206] In Fig.13, an embodiment is shown wherein the system 100 comprises a single reactor vessel 50 having a first part 30a for pre-treating the plastic waste and a second part 30b for pyrolyzing the pre-treated plastic waste. As discussed above, the first vessel part 30a of the vessel 50 corresponds to a cold zone and the second vessel part 30b of the vessel 50 corresponds to a hot zone, wherein, when the system is in operation, a temperature of the cold zone is lower than a temperature of the hot zone. The cold zone allows to perform a pre-treatment of the plastic waste comprising for example degassing of the plastic waste and regulating the temperature curve

[0207] On the other hand, in Fig.15, an embodiment is shown wherein the system comprises a first vessel 50 and a second vessel 90. As further schematically illustrated on Fig.15, a coupling device 93 is coupling an output of the first vessel 50 with an input of the second vessel 90. Both embodiments, the single reactor vessel configuration, as well as the two- vessel configuration comprise an annular condensation chamber 54 for condensing pyrolysis oil gas.

[0208] For a single vessel reactor type, as shown on Fig.13, the first annular condensation chamber 54 comprises an inlet 51 for receiving pyrolysis oil gas produced in the second reactor part 30b and an outlet 52 for outputting oil resulting from condensation of the pyrolysis oil gas received.

[0209] In other words, as schematically illustrated on Fig.14, the cold zone part of the vessel 50 is made up of three layers, the innermost is for raw material conveying and preconditioning, the middle layer is for oil gas circulation and condensation while the outermost part is for heat insulation.

[0210] In embodiments, the inner and outer radial walls that are forming the first annular condensation chamber 54 may be considered as walls or wall portions of the vessel 50 surrounding the first part 30a of the vessel, i.e. the cold zone of the vessel.

[0211] In embodiments comprising a single vessel, as shown on Fig.13, the second reactor part 30b comprises an inner radial wall 91a and an outer radial wall 91b surrounding and spaced from the inner radial wall 91a so as to form an annular heating chamber 68 surrounding the second reactor part 30b. The annular heating chamber 68 allows for heating up the second reactor part 30b, which corresponds to the hot zone of the reactor. Generally, the second reactor part 30b comprises a further heat insulating jacket 67b surrounding the outer radial wall 91b of the second reactor part 30b.

[0212] In other words, the hot zone of the reactor is also composed of three layers: the innermost layer is for raw material conveying and pyrolysis, the middle layer is for circulation of heating media, while the outermost layer is for heat insulation.

[0213] In Fig. 13, the insulation jackets 67 and 67b are represented by the hatched areas.

[0214] In embodiments as illustrated on Fig.13, the inner and outer radial walls that are forming the annular heating chamber 68 may be considered as walls or wall portions of the vessel 50 comprising the second reactor part 30b.

[0215] In embodiments, as shown on Fig.15 comprising a first 50 and a second 90 vessel, the inner 91a and outer 91b radial walls of the second vessel 90 are forming the annular heating chamber 68.

[0216] In embodiments, as schematically shown on Fig.16 and Fig.17, the system for pyrolysis of plastic waste may comprise a feedback device 40 configured for suppling pyrolysis oil gas to the condensation chamber 54.

[0217] For the system 100 shown on Fig.16 using the single reactor vessel configuration, the pyrolysis oil gas produced in the second reactor part 30b is supplied by the feedback device 40 to the inlet 51 of the first annular condensation chamber 54. Thereto, the feedback device 40 comprises a first gas input coupled with the reactor output 33 so as to receive pyrolysis oil gas and a gas output coupled with the inlet 56 of the first annular condensation chamber 54. In this way, the feedback device 40 may supply oil gas to the first condensation chamber 54. Similar for the system 100 shown on Fig.17 using the two vessel reactor configuration, the pyrolysis oil gas produced in the second vessel 90 is supplied by the feedback device 40 to the inlet 56 of the first annular condensation chamber 54. Thereto, the feedback device 40 comprises a first gas input coupled with the output 33b of the second vessel 33 outputting pyrolysis oil gas. In this way the feedback device receives pyrolysis oil gas from the second vessel 90. The feedback device 40 further has a gas output coupled with the inlet 56 of the first annular condensation chamber 54. In this way, the feedback device 40 may supply oil gas to the first condensation chamber 54 surrounding the first vessel 50.

[0218] In embodiments, as illustrated on Fig.16 and Fig. 17, the pyrolysis system 100 comprises a buffer hopper 20 for supplying plastic waste to the first vessel, and a supply system 70 for feeding the buffer hopper with plastic waste.

[0219] In embodiments, the buffer hopper 20 comprises a funnel portion 20a and a neck portion 20b, and wherein the neck portion is coupled to the reactor input 32 of the first reactor vessel 50.

[0220] In embodiments, the supply system 70 comprises a conveyer screw 72 for transporting plastic waste from a primary supply input 71 to the buffer hopper 20. The conveyer screw 72 is located within an elongated tank 75. In embodiments, the tank 75 may be a tube. The supply system 70 may also be named screw conveyor feeder tube.

[0221] Typically, the plastic input material enters the supply input 71 at ambient temperature which is at temperatures between -20°C and +40°C.

[0222] In embodiments, the elongated tank 75 comprises a first radial wall 76 and a second radial wall 77 at least partly surrounding the first radial wall 76 and spaced from the first radial wall so as to form a second annular condensation chamber 79 surrounding at least part of the elongated tank 75. The second annular condensation chamber 79 comprises a gas inlet 73 coupled with a gas outlet 53 of the first annular condensation chamber 54, and an oil and gas output 74. In this way, the pyrolysis system comprises two condensation chambers 54, 79 placed in series.

[0223] Advantageously, by providing two condensation chambers in series, pyrolysis oil gas may circulate longer and heat from the pyrolysis oil gas may be recovered more efficiently and oil condensation may be optimized.

[0224] As the gas travels through the first condensation chamber 54, it loses its heat to the material contained in the cold zone of the reactor, i.e. the first reactor part 30a. This causes the oil gas to condense and oil is collected at the outlet 52 of the cold first reactor part. The gases that are not yet condensed, mostly lower molecular weight are sent to the second condensation chamber 79 wherein the oil gas may further circulate and further condensate whilst heating up the incoming plastic waste raw material.

[0225] Advantageously, the elongated tank 75 comprises a further heat insulating jacket 78 surrounding the second radial wall 77 of the elongated tank 75. In this way, escape of heat from the second condensation chamber 79 is reduced.

[0226] In embodiments, the feedback device 40 comprises a hydrogenation unit 48 configured for hydrogenating the pyrolysis oil gas received from the second reactor part 30b. The hydrogenation unit 48 collects the oil gas received from the output of the reactor. In these embodiments, the feedback device 40 comprises a second gas input for receiving hydrogen.

[0227] In some embodiments, the hydrogenation unit 48 may contain a catalyst and be conditioned to be in low pressure using pressure valves. In other embodiments, no catalyst is used.

[0228] The hydrogenating unit 48 is configured for hydrogenating unsaturated hydrocarbons and other molecules, wherein the other molecules comprise at least halogens. Such a hydrogenation unit 48 is known in the art.

[0229] The feedback system 40 is configured for feeding back the oil gas exiting the hydrogenation unit 48 to the first condensation chamber 54 surrounding the first reactor part, i.e. the cold zone of the reactor. The hot oil gas coming from the hydrogenation unit, once entering the condensation chamber will flow backwards in opposite direction of the plastic material that is moving through the reactor. This circulation of the oil gas is made possible because of a pressure difference, mainly driven by the gas temperature.

[0230] In embodiments, the circulation of the oil gas in the first condensation chamber 54 and / or second condensation chamber 79 may be enhanced by using a pump.

[0231] The hydrogen required for the hydrogenation unit 48 may be produced on-line by the pyrolysis system 100. This is schematically illustrated for the embodiments shown on Fig.16 and Fig.17 wherein the pyrolysis system 100 comprises a separation tank 41 coupled to the oil and gas output 74 of the second annular condensation chamber 79, and a hydrogen generation unit 42.

[0232] The separation tank 41 is configured for separating noncondensable gases from oil and the hydrogen generation unit 42 is configured for receiving non-condensable gases from the separation tank 41 and for outputting hydrogen gas. The hydrogen generation unit 42 is further configured for supplying hydrogen to the hydrogenation unit 48.

[0233] In embodiments, the hydrogen unit 42 may be a high-pressure flash reactor configured for cracking the incondensable gases and produce hydrogen

[0234] In embodiments, the hydrogen generation unit 42 comprises a pressurized autoclave gas reactor, and heating means for heating the gas reactor. In embodiments, the heating means are configured for heating the gas reactor to temperatures in a range between 900°C and 1300°C.

[0235] In embodiments, the pyrolysis system may further comprise a pressure regulator 43 for controlling a pressure difference between the hydrogen generation unit 42 and the hydrogenation unit 48.

[0236] In embodiments, the pyrolysis system may comprise a gas filtering device 44 located between the hydrogen generation unit 42 and the hydrogenation unit 48. The gas filtering device 44 is configured for filtering out syngas that is not hydrogen. Advantageously, the syngas that is not hydrogen may be used as a combustion gas for heating the second reactor part.

[0237] In embodiments, as schematically illustrated on Fig.16 and Fig.17, the pyrolysis system comprises a channel 45 configured for transporting the syngas that is not hydrogen to a heating device.

[0238] Reference signs

[0239]

Claims

Claims1. A system (100) for recycling a plastic feedstock (10) by pyrolysis comprising at least a first vessel (50) having:- an input (32) for receiving the plastic feedstock (10);- a first conveyer screw system (31) configured for conveying the received plastic feedstock from a first end (50a) to a second end (50b) of the first vessel (50); and- a first vessel part (30a) and a second vessel part (30b), and wherein the first vessel part is separated by the second vessel part by a buffer space (34) for building up a buffer of plastic feedstock inside the first vessel and / or to enable plastic feedstock of different sizes or melt temperatures to be mixed up before entering the second part.

2. The system of claim 1 wherein the first vessel part (30a) and the second vessel part (30b) of the first vessel correspond to respectively a first operational zone and a second operational zone of the first vessel, and wherein the system is configured for operating within a first temperature range in the first operational zone and within a second temperature range in the second zone, and wherein a temperature in the first operational zone is lower than a temperature in the second operational zone.

3. The system of claim 2 wherein, when the system is in operation, said first operational zone has a temperature in a range between -25°C to 200°C, preferably in a range between -10°C to 200°C, more preferably in a range between -10°C to 150°C, and said second operational zone has a temperature in a rangebetween 150°C to 650°C, preferably in a range between 250°C to 650°C, more preferably in a range between 350°C and 550°C.

4. The system according to any of previous claims wherein, when the system is in operation, said buffer space (34), is filled up with plastic feedstock.

5. The system according to any of previous claims wherein the first conveyer screw system (31) comprises a first conveyor screw (31a) extending from a begin side to an end side of the first conveyer screw and a second conveyor screw (3 lb) extending from a begin side to an end side of the second conveyer screw, and wherein said first part (30a) and second part (30b) accommodate respectively the first conveyor screw (31a) and the second conveyor screw (31b), and wherein said first and second conveyer screw are oriented in a same direction and wherein the begin side of the second conveyer screw is separated from the end side of the first conveyer screw so as to create a space between the first and second conveyer screw, and wherein said space between the first and second conveyer screw is forming said buffer space (34).

6. The system according to claim 5 wherein the first and / or second conveyer screw of the first vessel are profiled conveyer screws.

7. The system of claim 5 or claim 6 wherein the begin side of the first conveyer screw (31a) is configured for receiving the plastic feedstock (10) through the input (32) of the first vessel.

8. The system according to any of claims 5 to 7 wherein the first conveyer screw system (31) comprises a first hollow shaft (52) forming a first tubular element (52) for receiving a first heating means (60) so as to generate radial heating from inside of the first vessel (50).

9. The system according to claim 8 wherein an inner screw (55) is located within said first tubular element (52), and wherein said inner screw (55) is configured for conveying the first heating means (60) through the first tubular element (52), preferably wherein the inner screw (55) is extending along a central axis (Y) of the hollow shaft (52).

10. The system according to claim 9 wherein the inner screw (55) is rotatable around a rotation axis parallel with the central axis (Y) of the first hollow shaft, preferably the rotation axis of the inner screw is coinciding with the central axis (Y) of the first hollow shaft.

11. The system according to claim 9 or claim 10 wherein said inner screw (55) is a shaftless inner screw.

12. The system according to any of claims 9 to 11 wherein said first heating means (60) is hot char (15).

13. The system according to claim 12 wherein the inner screw (55) is configured for conveying the char (15) from an entrance side(87) of the first tubular element for receiving the char to an exit side (88) of the first tubular element for outputting the char, preferably wherein the exit side is located opposite the entrance side of the tubular element.

14. The system according to claim 13 wherein said entrance side (87) of the first tubular element for receiving the char (15) is located at said second end (50b) of the first vessel (50) such that the hot char is moving in a direction opposite to the direction of the plastic feedstock (10) moving in the first vessel (50) from the first end (50a) to the second end (50b).

15. The system according to any of claims 9 to 14, wherein when depending on claim 5, said first (31a) and second conveyer screw (3 lb) of the first conveyer screw system (31) are configured for rotating in a first rotational direction and said inner screw (55) is configured for rotating in a second rotational direction, opposite the first rotational direction.

16. The system according to any of claims 9 to 15 wherein said inner screw (55) comprises a first screw part (55a) from a begin side to an end side of the first screw part and a second screw part (55b) extending from a begin side to an end side of the second screw part, and wherein the begin side of the second screw part is separated from and facing the end side of the first screw part such that a char buffer space (18) is created within the tubular element (52) between the first (55a) and second (55b) screw part, preferably the first and second screw part are extending along the central axis (Y) of the hollow shaft (52).

17. The system according to claim 16 wherein, when the system is in operation, said char buffer space (18) is filled up with char.

18. The system according to any of claims 9 to 17 wherein, when the system is in operation, the inner screw (55) transporting the char is configured for increasing an incoming material temperature of the plastic feedstock that is in a range between -25°C to +45°C to a material temperature up to at least 100°C, preferably up to at least 150°.

19. The system according to any of previous claims wherein the first vessel (50) is a vessel for pre-treating the plastic feedstock, and wherein the first vessel comprises an output for outputting the pre-treated plastic feedstock, and wherein the system further comprises: a second vessel (90) for pyrolyzing the pre-treated plastic feedstock, and a connection element (93) coupling the output (33) of the first vessel (50) with an input of the second vessel (90).

20. The system according to claim 19 wherein the second vessel comprises a second conveyer screw system (58) configured for conveying the pre-treated plastic feedstock from a first end (90a) to a second end (90b) of the second vessel (90).

21. The system according to claim 19 or 20, when depending on claim8, comprises a char conveyer (95) configured for conveying char outputted from the second vessel (90) to the entrance side (87) of the first tubular element (52) of the first vessel (50).

22. The system according to claim 21 wherein said char conveyer (95) comprises a char conveying screw (96).

23. The system according to any of claims 20 to 22 wherein the second conveyer screw system (58) comprises a second hollow shaft (52b) forming a second tubular element (52b) for receiving a second heating means (60b) so as to generate radial heating from inside of the second vessel (90).

24. The system of claim 23 comprising a fluid supply configured supplying any of: hot air, hot exhaust smoke or any other suitable hot medium to an entrance side (87b) of the second tubular element (52b) of the second vessel.

25. The system according to any of previous claims, wherein said first vessel (50) comprises:- an inner radial wall (51a) radially delimiting the first vessel,- an outer radial wall (51b) surrounding, or at least partly surrounding, and spaced from the inner radial wall (51a) so as to form a first annular condensation chamber (54) surrounding or at least partly surrounding the first vessel 50, and wherein said first annular condensation chamber (54) comprises an inlet (56) for receiving pyrolysis oil gas and an outlet (57) for outputting oil resulting from condensation of the pyrolysis oil gas received.

26. The system according to claim 25 wherein the first vessel (50) comprises:-a heat insulating jacket (67) surrounding said first annular condensation chamber.

27. The system according to claim 25 or 26 wherein, when depending on claim 19, said inlet (56) of the first annular condensation chamber (54) is configured for receiving pyrolysis oil gas produced in the second vessel (90).

28. The system according to claim 27 wherein said second vessel comprises a pyrolysis oil gas output (33b) for outputting pyrolysis oil gas, and wherein said pyrolysis oil gas output (33b) of the second vessel (90) is coupled with said inlet (56) of the first condensation chamber (54) of the first vessel (50).

29. The system according to any of previous claims, wherein, when depending on claim 19, said second vessel (90) comprises an inner radial wall (91a) and an outer radial wall (91b) surrounding and spaced from the inner radial wall (91a) so as to form an annular heating chamber (68) surrounding the second vessel.

30. The system according to claim 29 wherein the second vessel (90) further comprises a further heat insulating jacket (67b) surrounding the annular heating chamber.

31. The system according to claim 29 or 30, wherein the annular heating chamber (68) comprises an input for receiving a heating medium, preferably wherein the heating medium is a hot gas or a hot liquid.

32. The system according to any of claims 25 to 31 comprising• a feedback device (40) configured for suppling pyrolysis oil gas produced in the second vessel (30b) to said inlet (51) of the first annular condensation chamber (51), and wherein said feedback device (40) comprises a first gas input coupled with the pyrolysis oil gas output of the second vessel so as to receive pyrolysis oil gas and a gas output coupled with said inlet (51) of the first annular condensation chamber (51).

33. The system according to claim 32 wherein said feedback device(40) comprises a hydrogenation unit (48) configured for hydrogenating the pyrolysis oil gas received from the second vessel, and wherein said feedback device (40) comprises a second gas input for receiving hydrogen.

34. The system according to claim 33 wherein said hydrogenating unit is configured for hydrogenating unsaturated hydrocarbons and other molecules, wherein said other molecules comprise at least halogens.

35. The system according to any of previous claims comprising• a buffer hopper (20) for supplying plastic waste to the first vessel (50),• a plastic supply system (70) comprising a conveyer screw (72) for transporting plastic waste from a primary plastic supply input (71) to the buffer hopper (20), and wherein said conveyer screw (72) is located within an elongated tank (75).

36. The system according to claim 35 wherein, when depending on any of claims 25 to 35, saidfirst annular condensation chamber (54) surrounding the first vessel further comprises a gas outlet (53), and wherein said elongated tank (75) comprises a first radial wall (76) and a second radial wall (77) at least partly surrounding said first radial wall (76) and spaced from the first radial wall so as to form a second annular condensation chamber (79) surrounding at least part of the elongated tank (75), and wherein said second annular condensation chamber (79) comprises a gas inlet (73) coupled with the gas outlet (53) of the first annular condensation chamber (54), and an oil and gas output (74).

37. The system according to claim 36 wherein said elongated tank(75) comprises a further heat insulating jacket (78) surrounding said second radial wall of the elongated tank.

38. The system according to claim 36 or claim 37 further comprising• a separation tank (41) coupled to said oil and gas output(74) of the second annular condensation chamber (79), and wherein said separation tank (41) is configured for separating non-condensable gases from oil,• a hydrogen generation unit (42) configured for receiving non-condensable gases from the separation tank (41) and for outputting hydrogen gas, and wherein said hydrogen generation unit (42) is further configured for supplying hydrogen to said hydrogenation unit (48).

39. The system according to claim 38 wherein said hydrogen generation unit (42) comprises a pressurized autoclave gas reactor, and heating means for heating said gas reactor, preferably wherein the heating means are configured for heating the gas reactor to temperatures in a range between 900°C and 1300°C.

40. The system according to claim 38 or 39 comprising a pressure regulator (43) for controlling a pressure difference between the hydrogen generation unit (42) and the hydrogenation unit (48).

41. The system according to any of claims 38 to 40 comprising a gas filtering device (44) located between the hydrogen generation unit (42) and the hydrogenation unit (48), and wherein the gas filtering device (44) is configured for filtering out syngas that is not hydrogen.

42. The system according to claim 41 comprising a channel (45) configured for transporting said syngas that is not hydrogen to a heating device.

43. The system according to any of previous claims further comprising:-an oxygen removing device (1) configured for removing oxygen from the plastic feedstock before the plastic feedstock is entering the first vessel.

44. The system according to claim 43 wherein the oxygen removing device (1) comprises a transfer chamber (2) having an input opening (4) for receiving the feedstock and an output opening (5) coupled tothe input (32) of the first vessel for discharging the plastic feedstock into the first vessel, a rotor (3) disposed within said transfer chamber and configured for dividing the transfer chamber into rotatable chamber sections (6a, 6b, 6c, 6d), and wherein by rotation of said rotor (3) each of said chamber sections is sequentially positionable into at least:-a first position for receiving feedstock through said input opening of the transfer chamber and thereby filling the chamber section with feedstock,-a second position wherein a wall portion of the transfer chamber is closing off the filled chamber section such that feedstock is no longer receivable in the chamber section and feedstock is also not dischargeable from the chamber section, and-a third position for discharging the filled chamber section through said output opening of the transfer chamber, and wherein said oxygen removing device further comprises a vacuum pump configured for pumping any of or a combination of air, water vapour and VOC gases from each chamber section when positioned in said second position.

45. The system according to claim 44 wherein the oxygen removing device comprises a seal (8) configured such that each chamber section when positioned in the second position is sealingly closed off from an adjacent chamber section located in the first position and / or an adjacent chamber section located in the third position.

46. The system according to claim 45 wherein said seal (8) of the oxygen removing device is coupled to an inner wall of the transfer chamber (2).

47. The system according to claim 45 or 46 wherein said seal (8) of the oxygen removing device is a flexible seal configured to allow the rotor (3) to rotate freely for moving the chamber sections from one position to another position.

48. The system according to any of claims 45 to 47 wherein said seal of the oxygen removing device is flexible flap, preferably an elastomeric flexible flap.

49. The system according to any of claims 45 to 48 wherein said oxygen removing comprises three or four chamber sections (6a, 6b, 6c, 6d).

50. The system according to any of claims 45 to 49 wherein said rotor(3) of the oxygen removing device comprises a rotation axis and a plurality of blades connected to the rotation axis, and wherein each chamber section is delimited by two adjacent blades of said plurality of blades.

51. The system according to any of claims 45 to 50 wherein the rotor of the oxygen removing device comprises two or more blades, preferably four blades defining four adjacent chamber sections.

52. The system according to any of claims 45 to 51 wherein each chamber section of the oxygen removing device is positionable into a fourth position located between the third and firstposition, and wherein when in said fourth position a further wall portion of the transfer chamber is closing off the chamber section such that no feedstock can be received or discharged from the chamber section when in the fourth position.

53. The system according to any of claims 45 to 52 wherein the oxygen removing device further comprises a motor for rotating said rotor.

54. The system according to any of claims 45 to 53 wherein the oxygen removing device comprises a controller for controlling rotation of said rotor and controlling said vacuum pump.

55. The oxygen removing device according to any of claims 45 to 54 wherein said transfer chamber of the oxygen removing device comprises a pump opening (7) coupled with a suction side of said vacuum pump and wherein said pump opening is configured such that for a chamber section being positioned in the second position air and / or water vapour is pumped from the chamber section.

56. The system according to any of claim 45 to 55 wherein each of said chamber sections of the oxygen removing device is configured for receiving pieces of plastic feedstock having dimensions up to at least 5 mm, preferably up to at least 5 cm, more preferably up to at least 12 cm.

57. The system according to any of previous claims wherein the plastic feedstock comprises pieces of plastic waste material and / or pieces of rubber waste material.

58. The system according any of previous claims wherein the system is a continuous-type system wherein, when the system is in operation, plastic feedstock is continuously fed into the first vessel.

59. The system according to any of previous claims wherein said first vessel is extending axially along a first central axis (Yl), preferably wherein the first central axis is parallel or perpendicular with respect to a floor level.

60. The system according to any of previous claims wherein said second vessel is extending axially along a second central axis (Y2).

61. The system according to claim 60 wherein the second central axis(Y2) is parallel with the first central axis (Yl).

62. The system according to claim 60 or 61 wherein the first (Yl) and second (Y2) central axes are parallel with a floor level and wherein said first and second central axis are located respectively at a first and a second height with respect to the floor level and wherein the first height is higher than the second height.

63. The system according to claim 60 wherein said second central axis(Y2) is perpendicular with said first central axis (Yl).

64. The system according to any of previous claims wherein the first conveyer screw system (31) comprises a single screw and wherein said buffer space (34) is formed within a portion of thesingle screw, preferably wherein within said portion of the single screw one or more blades of the single screw are omitted for forming the buffer space.

65. The system according to any of previous claims wherein, when depending on claim 5, said first (31a) and said second (31b) conveyer screw of the first conveyer system (31) are provided with respectively a first and a second motor such that a speed of the first conveyer screw and a speed of the second conveyer screw are independently controllable.

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