Thermal conversion reactor for the conversion of plastics into synthesis gases which can be condensed to give plastic oils

Abstract

The invention relates to a thermal conversion reactor (5) for a conversion by cracking, under an anaerobic or inert atmosphere, of plastics into synthesis gases which can be at least partially condensed to give plastic oils, the reactor comprising: - a reaction chamber (50); - a thermal cracking device (8) comprising a heat exchanger (80) which is arranged inside the reaction chamber and has an upper section (82) having a conical, ovoid, pyramidal or hemispherical shape and ending with a tip (83) arranged opposite and below a top inlet (53) for introducing the plastics, and a main heating system (81) coupled to the heat exchanger (80) in order to heat it to a predefined cracking temperature; and - a top outlet (51) for recovering the synthesis gases which is arranged above the tip (83) of the heat exchanger (80).

Description

TITLE: Thermal conversion reactor for converting plastics into synthesis gases condensable into plastic oils [Technical field]

[0001] The invention relates to a thermal conversion reactor for conversion by cracking, under an anaerobic or inert atmosphere, of plastic materials into synthesis gases condensable into plastic oils, and into solid reaction products.

[0002] The thermal conversion reactor is particularly suitable for thermal and catalytic conversion, i.e. thermal conversion promoted by catalysis using a catalyst coated with and mixed with the plastics which are in a pasty state.

[0003] It also relates to a thermal conversion plant, and advantageously also a catalytic one, for conversion by cracking of solid plastic materials into plastic oils, the plastic oils being obtained by condensation from the synthesis gases produced in the thermal conversion reactor.

[0004] The invention thus finds a preferred application for the recycling of plastic materials, and in particular plastic waste, in order to produce plastic oils which will make it possible to produce plastic, thus placing the invention in a circular economy sector for plastics, known as the “plastic-to-plastic” sector. [State of the art]

[0005] Plastic polymers are mainly obtained from naphtha, which is produced by refining oil, or from natural gas. These plastics obviously pose an end-of-life management problem, with an environmental impact that requires serious consideration of the treatment of these plastics, and in particular plastic waste.

[0006] A processing sector implements the recovery of plastic materials (and in particular plastic waste) by treating them to convert the long polymer chains into short polymer chains, or even into monomers, in order to serve as resources for the production of new plastics, by replacing a fraction of naphtha, of fossil origin, in the traditional petrochemical sector. This sector, called in English "plastic-to-plastic", "plastic-to-monomer" or "plastic-to-naphtha", offers an economic way of recycling plastic waste which not only contributes to a beneficial reuse of waste, but also constitutes a solution for the petrochemical sector which would respond to a possible shortage of hydrocarbon resources, as well as the "mass balance" rule which consists of introducing renewable resources or plastic waste in addition to fossil resources in the plastics manufacturing process.

[0007] A technology for processing plastic materials or waste consists of thermal cracking (or pyrolysis) inside a thermal conversion reactor (or cracking reactor), generally promoted by a catalyst, in order to degrade the polymers to obtain chemical products with lower molar masses, including synthesis gases, at least part of which is condensed to obtain plastic oils; these plastic oils thus form a secondary raw material that can be exploited directly, as a total or partial replacement for fossil products from refineries, within the conventional petrochemical sector, thus meeting the "mass balance" rule.

[0008] However, plastic waste is generally of diverse and varied natures, sometimes contaminated or complex to treat, directly impacting the quality of plastic oils. There is therefore a need to improve the processing of plastic materials to obtain plastic oils with properties that comply with those required by the plastics manufacturing sector. [Summary of the invention]

[0009] An aim of the invention is to propose a thermal conversion reactor which is suitable for promoting the production of plastic oils having qualities meeting the requirements of the petrochemical sector, in particular in the selectivity of the cuts of the polymer chains into molecules of lower molecular weight.

[0010] Another object of the invention is to have control over cracking in order to maintain a quality of plastic oil that is both reproducible and repeatable, while having a high yield in plastic oil conversion, in particular at least 45% conversion of plastic materials into quality plastic oils following the operational conditions, or even up to 85% conversion.

[0011] To this end, the invention provides a thermal conversion reactor for conversion by cracking, under an anaerobic or inert atmosphere, of plastic materials into synthesis gases condensable at least partially into plastic oils, and into solid reaction products, said thermal conversion reactor comprising: - a reaction chamber having a high wall on which a high inlet is provided for introducing plastic materials, a low wall on which a low outlet is provided for evacuating the reaction products solids, and a peripheral wall extending between the upper wall and the lower wall over an enclosure height measured along a central axis; - a thermal cracking device comprising a heat exchanger arranged inside the reaction chamber so that an annular space is provided between the heat exchanger and the peripheral wall, said heat exchanger having an upper section having a conical, ovoidal, pyramidal or hemispherical shape centered on a central axis and ending in a top arranged opposite and below the upper inlet, said thermal cracking device comprising a main heating system coupled to the heat exchanger to heat it to a predefined cracking temperature; - a high outlet for recovery of synthesis gases, located above the top of the heat exchanger.

[0012] In addition, this thermal conversion reactor includes: - a tubular guide extending the upper inlet and extending inside the reaction chamber from the upper wall over a guide height, this tubular guide having a free termination located at a given non-zero distance from the top of the heat exchanger; and - a secondary heating system coupled to the tubular guide to heat it to a predefined guide temperature.

[0013] Thus, the invention proposes a thermal conversion reactor (and advantageously thermal and catalytic conversion in the presence of catalyst in the plastics) which forms the seat of the cracking reactions with the aim of producing synthesis gases which are at least partially condensable into plastic oils.

[0014] The introduction of the plastic materials, preferably fluidized (or in a pasty state) as described later, is done through the upper inlet, in order to flow by gravity onto the top of the heat exchanger and then along the peripheral surface (conical, ovoidal, pyramidal or hemispherical) of this heat exchanger.

[0015] The peripheral surface of the heat exchanger thus forms the cracking zone or surface, heated by the main heating system, with a geometry (conical, ovoidal, pyramidal or hemispherical) which promotes the gravitational flow of the plastics, while providing an increased contact (or cracking) surface in order to promote heat transfer to the polymer matrices of the plastics. These conical, ovoidal, pyramidal or hemispherical shapes of the heat exchanger in fact constitute flared or tapered shapes, which widen from the base to the top, so as to promote descent by gravity from the top to the base, and contact along the peripheral surface.

[0016] The energies required for the cracking reactions are thus provided instantly as close as possible to the raw material, composed of polymer matrices, and advantageously also of the catalyst mixed with the plastic materials.

[0017] The conical, ovoidal, pyramidal or hemispherical shape of the heat exchanger also promotes gravitational decantation of solid reaction products towards the bottom (in other words towards the lower wall) so as to purify the synthesis gases so as not to contaminate the plastic oils produced. Furthermore, these shapes promote the circulation of the generated synthesis gases without disturbance zones.

[0018] Such a geometry of the heat exchanger also promotes the undisturbed circulation of the synthesis gases generated during the cracking reactions, as well as the decantation of solid reaction products (such as chars and, where applicable, deactivated / used catalyst) towards the lower wall on which the lower outlet is provided. Thus, this geometry allows gravity decantation of the solid reaction products so as to purify the synthesis gases so as not to contaminate the plastic oils produced at the end.

[0019] As mentioned, the upper outlet for syngas recovery is arranged above the top of the heat exchanger, so that a zone is provided around the heat exchanger and between this upper outlet and a base of the upper section of the heat exchanger, which constitutes a thermal agitation zone. Such a thermal agitation zone allows homogenization of the syngas and termination of the cracking reactions before the extraction of the syngas at this upper outlet. The volume of this thermal agitation zone influences the residence time of the syngas and thus the lengths of molecular chains and molecular reactions that take place in this thermal agitation zone.In other words, this thermal agitation zone, present within the reactor, allows a significant contact time between the polymer matrices of the plastic materials (and where appropriate also the catalyst) with the heat exchanger, optimizing the cracking reaction to obtain an optimum yield in conversion into synthesis gas condensable into plastic oils.

[0020] With such a reactor, it is possible to obtain synthesis gases that can be condensed into plastic oils mainly composed of paraffins and olefins, with a minority of cycles and aromatics. The compounds present in such plastic oils advantageously have carbon chains between C5 and C20, preferably between C7 and C13. The density of these plastic oils can be between 600 and 900 kg / m3, a final boiling point between 350 and 380°C and with a water content between 300 and 500 ppm maximum. To be compatible with industrial petrochemical processes, the plastic oils obtained advantageously contain a certain maximum level of contaminants; the limit of oxygenated, nitrogenous, sulfurous, halogenated and phosphorous compounds will be between 0 and 50 ppm.

[0021] In addition, the tubular guide is advantageous in promoting the flow and flow direction of the plastic materials, preferably fluidized, towards the peripheral wall of the heat exchanger which forms the cracking zone.

[0022] Furthermore, in addition to guiding the flow of plastics, this tubular guide allows, thanks to the heating provided by the secondary heating system, to provide a quantity of energy to the polymer matrices, without physical contact, before the cracking zone where physical contact is established between the plastics and the heat exchanger. This energy input, obtained thanks to this secondary heating system, therefore makes it possible to initiate the cracking reactions, at the start of the reactor, in order to allow a quasi-instantaneous cracking reaction when the plastics come into contact with the heat exchanger.

[0023] Also, the tubular guide and the secondary heating system together promote the management of the flow of the polymer matrices of the fluidized plastic materials, in order to promote their encounters with the exchange surfaces provided by the heat exchanger, so as to ensure optimal contact between the fluidized plastic materials and the cracking zone allowing optimal transfers of thermal energy to the polymer matrices of the plastic materials, and moreover to obtain synthesis gases condensable into plastic oils having the desired quality.

[0024] In addition, the tubular guide allows the separation, over its entire height, of the synthesis gases rising from the cracking zone (in this case the contact surface of the heat exchanger) from the flow of fluidized plastic materials descending from the upper inlet, which promotes the thermal agitation of the synthesis gases and therefore the homogenization of the synthesis gases and the termination of the depolymerization reactions before the extraction of the synthesis gases towards the condenser.

[0025] In addition, the upper outlet is advantageously arranged above the free end of the tubular guide.

[0026] In other words, the free end of the tubular guide is located between the top of the heat exchanger and the high outlet. Thus, the synthesis gases rise from the cracking zone, past the free end of the guide tubular, and circulate around the tubular guide before reaching the upper outlet, thus promoting the homogenization of the synthesis gases and the termination of the depolymerization reactions.

[0027] Alternatively, the guide temperature is equivalent to the cracking temperature, plus or minus 5%, in order to promote initiation of cracking reactions before contact of the plastics with the heat exchanger. Also, by heating the tubular guide to the cracking temperature, the reactor is maintained in isothermal conditions promoting the production of a reproducible and repeatable quality of plastic oil meeting the quality requirements sought by the "Plastic to Plastic" sector.

[0028] The guide temperature is therefore advantageously equivalent to the cracking temperature, for example between 300 and 600°C, and again for example between 400 and 500°C, and preferably between 450 and 500°C, so as to provide maximum energy to the fluidized plastic materials, making it possible to lower the energies necessary for thermal (and possibly catalytic) cracking during contact between the plastic materials and the conical, ovoidal, pyramidal or hemispherical heat exchanger.

[0029] Alternatively, the guide height is between 0.1 and 0.5 times the enclosure height, for example between 0.30 and 0.35 times the enclosure height.

[0030] Such a guide height is advantageous in order to promote the flow and the guide direction of the fluidized plastic materials towards the cracking zone of the heat exchanger.

[0031] In a particular embodiment, the distance between the free end of the tubular guide and the top of the heat exchanger is between 0.05 and 0.3 times the enclosure height.

[0032] This distance improves the management of the flow of the polymer matrices of the fluidized plastic materials, advantageously containing the catalyst, in order to promote their encounters with the exchange surfaces provided by the heat exchanger, so as to ensure optimal contact between the fluidized plastic materials and the cracking zone allowing optimal transfers of thermal energy to the polymer matrices of the plastic materials, and moreover to obtain synthesis gases condensable into plastic oils having the desired quality.

[0033] Advantageously, the tubular guide is centered on the central axis, in alignment with the upper section of the heat exchanger, of conical, ovoidal, pyramidal or hemispherical shape.

[0034] In a particular embodiment, the free end of the tubular guide has a mouth having a dimension greater than or equal to a diameter of the top of the heat exchanger.

[0035] In a particular embodiment, the upper section of the heat exchanger has a base, this upper section narrowing from its base to its top, and the heat exchanger has, in the extension of the base of the upper section, a lower section, for example of cylindrical shape.

[0036] This lower section extends the upper section (beyond its base) to facilitate flow along the exchanger, and in particular the gravity settling of solid reaction products. This lower section is not wider than the base of the upper section; for example, the lower section has a diameter equivalent to that of the base of the upper section.

[0037] Advantageously, the thermal conversion reactor has a total volume delimited by the upper wall, the lower wall and the peripheral wall, and in which a sub-volume of the thermal conversion reactor, located around the heat exchanger and between the upper wall and the base of the upper section of the heat exchanger, is between 0.4 and 0.9 times the total volume.

[0038] This sub-volume forms a thermal agitation zone in which the synthesis gases circulate and are agitated, and this sub-volume is sized to allow the completion of the cracking (or depolymerization) reactions and homogenization of the synthesis gases. This thermal agitation zone is thus present to allow a significant contact time between the plastics and the catalyst with the heat exchanger, optimizing the cracking reactions to obtain an optimum yield in conversion into synthesis gases condensable into plastic oils.

[0039] In other words, this sub-volume forms a stay zone located between the base of the upper section of the heat exchanger (location of the cracking reactions) and the upper wall (location of the synthesis gas evacuation) allowing homogenization of the synthesis gases and the termination of the cracking reactions so as to prevent the chemical recombination of short chains into long chains, with the aim of controlling the formation of aromatic molecules before the extraction of the synthesis gases. Regarding the base of the upper section.

[0040] According to one possibility, the upper section of the heat exchanger, conical, ovoidal, pyramidal or hemispherical in shape, has a height measured along the central axis from its base to its top, and which is between 0.1 and 0.5 times the enclosure height, and for example between 0.20 and 0.25 times the enclosure height.

[0041] Alternatively, the heat exchanger has an overall height measured along the central axis and which corresponds to a combined height of the upper section and the lower section, and this overall height is between 0.2 and 0.5 times the enclosure height, and for example between 0.35 and 0.45 times the enclosure height.

[0042] Thus, this overall height is relatively high so that the heat exchanger occupies a large space in the reactor and thus allows for a large contact surface for the cracking reactions.

[0043] According to one variant, the heat exchanger is hollow and has an internal orifice, and the main heating system comprises at least one regulated electrical resistance disposed inside said internal orifice.

[0044] Thus, the heat exchanger is heated internally, which allows the walls of this heat exchanger to be maintained at a regulated and constant temperature to promote an optimal reaction and a significant heating power guaranteeing a significant continuous energy supply.

[0045] According to another variant, the top of the heat exchanger is rounded, which is advantageous for promoting the flow of plastic materials on the surfaces of the heat exchanger.

[0046] In an advantageous embodiment, the peripheral wall of the reaction chamber has an internal diameter, and the upper section of the heat exchanger, of conical, ovoidal, pyramidal or hemispherical shape, has a maximum diameter or a maximum transverse dimension which is between 0.5 and 0.9 times the internal diameter, and for example between 0.7 and 0.8 times the internal diameter

[0047] According to one feature, the heat exchanger is mounted on a support fixed to the reaction chamber, so that the heat exchanger is located at a distance from the lower wall.

[0048] Thus, a space is provided between the heat exchanger and the lower wall of the reactor, so as to allow the recovery of solid reaction products. This arrangement promotes the circulation of the synthesis gases generated, without any disturbance zone, and facilitates the decantation of solid reaction products and, where appropriate, the deactivated catalyst.

[0049] According to a variant, the support extends over a support height from the lower wall of the reaction chamber, said support height being between 0.2 and 0.4 times the enclosure height, and for example between 0.20 and 0.25 times the enclosure height.

[0050] According to another feature, the heat exchanger is made of a refractory metal alloy or ceramic.

[0051] The invention also relates to a thermal conversion installation for conversion by cracking of solid plastic materials into plastic oils, said thermal conversion installation comprising at least: - a continuous supply line for solid plastic materials; - a catalyst supply line; - a preheating reactor connected to the continuous supply line for the solid plastic materials and to the catalyst supply line, said preheating reactor being configured to mix the solid plastic materials and preheat them to a preheating temperature in order to fluidize them, and to mix the fluidized plastic materials with the catalyst in order to obtain a pasty mixture at an outlet, the preheating temperature being lower than an activation temperature of the catalyst; - a thermal conversion reactor according to the invention, said thermal conversion reactor having its upper inlet in sealed fluid communication with the outlet of the preheating reactor, for a gravity flow of the pasty mixture on the upper section of the heat exchanger and a heating of the pasty mixture to the cracking temperature, which is higher than the preheating temperature and the activation temperature of the catalyst, under an anaerobic or inert atmosphere in order to be converted into synthesis gases condensable at least partially into plastic oils, and solid reaction products; - a synthesis gas recovery line connected to the upper outlet of the thermal conversion reactor, the synthesis gases containing at least condensable gases, said synthesis gas recovery line comprising at least one condenser shaped to at least partially condense the condensable gases of the synthesis gases into plastic oils; - a solid reaction product recovery line connected to the lower outlet of the thermal conversion reactor.

[0052] The thermal conversion reactor previously described is particularly suitable for operating with the preheating reactor which will make it possible to obtain, upstream, a pasty mixture formed from fluidized plastic materials (under the effect of preheating to the preheating temperature) which coat the catalyst; this mixture pasty, thus forming a homogeneous mixture of the catalyst within the fluidized plastic materials.

[0053] Thus, this thermal conversion installation makes it possible to preheat the plastic materials to the preheating temperature, while mixing them with the catalyst and then, within the thermal conversion reactor, to heat and crack the fluidized plastic materials to the cracking temperature continuously.

[0054] Preheating in the preheating reactor provides two particularly advantageous functions: the first function is to transmit a significant amount of energy to the plastics to change physical state and end up in a pasty state before the thermal conversion reactor, thus promoting the chemical cracking reaction; and the second function is to fluidize and homogenize the plastics (with the change of physical state between initially solid plastics, which will be fluidized in the preheating reactor), which will then come into contact with the heat exchanger having a large heat exchange surface with the plastics flowing by gravity onto the heat exchanger (which incidentally therefore forms a permeable bed heated to the cracking temperature).

[0055] This thermal conversion installation is therefore based on a separation of the energy inputs supplied to the polymer matrices of the plastic materials encapsulating / coating the catalyst. Within the thermal conversion reactor, the conversion is advantageously carried out under isothermal conditions over heating temperature ranges which can be fixed between 300 and 900°C.

[0056] Furthermore, these fluidized plastics are mixed with the catalyst inside the preheating reactor. In other words, the plastics are continuously fed into the preheating reactor to be mixed and preheated to the preheating temperature to fluidize them and these plastics are mixed at the same time with the catalyst inside the preheating reactor to obtain a pasty and homogeneous mixture.

[0057] In other words, this preheating reactor allows continuous coating or continuous encapsulation of catalysts inside the polymer matrices of plastics, like a discontinuous process called "batch" which can lead to non-homogeneity of the catalysts within the polymer matrices. This homogenization promotes the production of a plastic oil of stable and homogeneous quality and promotes the production of carbon chains between C5 and C17, thus avoiding the formation of long chains incompatible with the "plastic to plastic" process.

[0058] Advantageously, the preheating temperature is lower than 300°C, beyond which the beginning of degradation of the polymer matrices in contact with the catalyst would be observed. This energy input into the preheating reactor allows on the one hand the miscibility of the compounds by the fluidification of the polymer matrices of the plastics, and on the other hand to lower the energies necessary for cracking, thus allowing an instantaneous reaction within the thermal conversion reactor.

[0059] Thus the pasty mixture, at the outlet of the preheating reactor, is a miscible and homogeneous mixture of plastic materials and catalyst, and the solid reaction product obtained in the thermal conversion reactor contains the chars but also catalyst; the mixture of plastic materials and catalyst being made miscible thanks to the preheating in the preheating reactor.

[0060] By proceeding in this way, by introducing and mixing the catalyst at the level of the preheating reactor, a homogeneous mixture in a pasty state is obtained, because the catalyst is dispersed homogeneously in the fluidized plastic materials, which will promote the selectivity of the cutting of the polymer chains into molecules of lower molecular weight, and therefore improve the quality of the plastic oil in accordance with the requirements of the “Plastic to Plastic” sector.

[0061] The catalyst activation temperature is the temperature at which the catalyst is activated and chemically promotes the cracking reaction.

[0062] The catalyst, for example of the zeolite type, makes it possible to reduce the working temperatures in the thermal conversion reactor and the activation energies necessary to trigger the cracking reaction without disturbing the shape of the reaction products. A simultaneity of the thermal effect and the catalytic effect takes place when the catalyst mixed with plastics is introduced directly into the thermal conversion reactor. The catalyst thus allows an optimization of the overall yield to favor the recoverable oil fractions. The catalyst allows a selectivity of the reaction products and the obtaining of a cut of the carbon chains in order to have the desired quality of the oils and the desired properties.

[0063] The introduction of plastics and the catalyst, in a pasty state and homogeneously mixed, into the thermal conversion reactor makes it possible to optimize contact with the heated heat exchanger which provides the energy capacity triggering the cracking reaction of the plastics into synthesis gas (also called "syngas").

[0064] It should be noted that the cracking reaction occurs in an anaerobic atmosphere (in the absence of oxygen) or in an inert atmosphere, with a fixed and stable cracking temperature. This cracking reaction takes place during the simultaneous contact of the fluidized plastics, mixed with the catalyst, and the heated heat exchanger within the thermal conversion reactor, leading to the chemical cracking reaction and therefore the deconstruction of the polymers of the plastic. The use of a thermal conversion reactor in the form of a gravity column into which the plastics fall, significantly increases the contact time between the incoming plastics and the heated heat exchanger.

[0065] This installation allows a dissociation of the activation energy inputs to the plastics, between the energy input in the preheating reactor and the energy input in the thermal conversion reactor, in order to optimize the cracking reaction of the plastics. Indeed, this dissociation of the energy inputs makes it possible to segment the working temperatures according to the reactor considered and to work on a constant and stable temperature range within the thermal conversion reactor and therefore to obtain a selective cutting of the carbon chains present in the plastic oils.

[0066] Thus, the process allows to have: - a first input of activation energy, in the preheating reactor, at a preheating temperature within a temperature range for example between 20 and 290°C, at a rate of 40 to 70% of the total energy required to carry out the cracking reaction; and - a second input of activation energy, in the thermal conversion reactor, at a cracking temperature within a temperature range, for example, between 300 and 900°C, at a rate of 30 to 60% of the energy required to trigger the cracking reaction.

[0067] Thus, a large amount of the activation energy required for the cracking reaction is supplied to the preheating reactor, the thermal conversion reactor thus having to supply less energy to enable the plastics to be cracked.

[0068] In addition, synthesis gases (also called "syngas"), produced during the thermal and catalytic cracking of plastics, are extracted at the upper outlet, above the heat exchanger, in order to promote the settling of chars within the thermal conversion reactor and avoid the transfer of chars to the synthesis gas recovery line. This extraction of synthesis gases above The heat exchanger is also explained in the case of partial cracking reaction due to the possibility of different energies supplied between the bottom and the top of the thermal conversion reactor (for example due to heterogeneity of the different types of plastics). Also, this extraction of gases makes it possible to limit, or even avoid, the clogging of the synthesis gas recovery line.

[0069] Alternatively, inside the preheating reactor, the plastics and the catalyst are mixed by means of a screw conveyor.

[0070] Such an endless screw is advantageous for homogenizing the plastics and the catalyst within the pasty mixture.

[0071] According to one feature, the preheating temperature is between 20 and 290°C inside the preheating reactor.

[0072] It is recalled that this preheating makes it possible to provide, through heat, the energy necessary for the plastics to change state and go from a solid aspect to a pasty state, in particular with the aim of facilitating the homogenization of the plastics with the catalyst. This energy input provided to the mixture (plastics and catalyst) is a part of the total energy necessary for the cracking reaction (between 40 and 70% of the total energy) which will take place in the thermal conversion reactor. The preheating reactor therefore allows a dissociation of the energies involved during the reactions between the plastics and the catalyst.

[0073] According to an advantageous embodiment, the thermal conversion installation comprises, downstream or at the outlet of the preheating reactor, a flow meter for measuring a mass or volumetric flow rate of the pasty mixture, and the catalyst supply line comprises a metering system connected to the flow meter and configured to regulate a metering of a quantity of catalyst continuously introduced into the preheating reactor as a function of the mass or volumetric flow rate of the pasty mixture.

[0074] Thus, the dosing system allows the catalyst rate to be precisely dosed in relation to the mass or volumetric flow rate of the pasty mixture formed mainly from fluidized plastic materials; the aim being to have an optimal ratio between plastic materials and catalyst. The catalyst dosage and the temperature management in the preheating reactor and in the thermal conversion reactor thus make it possible to control the cracking reactions in the thermal conversion reactor in order to obtain an oil quality corresponding to the requirements of the "Plastic to Plastic" sector.

[0075] According to one possibility, the thermal conversion installation comprises, between the preheating reactor and the thermal conversion reactor, a material diffuser for a substantially homogeneous and uniform surface distribution of the pasty mixture on the upper inlet of the thermal conversion reactor, said material diffuser being heated to a diffusion temperature higher than the preheating temperature and lower than the cracking temperature.

[0076] If applicable, this diffusion temperature is lower than the activation temperature of the catalyst.

[0077] Such a material diffuser allows for a homogeneous and uniform surface distribution of the pasty mixture on the heat exchanger present in the thermal conversion reactor, in order to benefit from the entire energy capacity of the surfaces offered by the heat exchanger. This uniform diffusion of the incoming pasty material makes it possible to avoid a preferential flow path and promotes the residence time of the plastic materials in contact with the heat exchanger, to improve heat transfer during the cracking reaction.

[0078] This material diffuser therefore has several functions. The first function is to heat the pasty mixture entering the diffuser to temperatures higher than those used in the preheating reactor, with the aim of transferring a maximum of energy in the form of heat from the diffuser to the material and thus increasing the energy input within the material promoting the cracking reactions with the catalyst which will take place in the thermal conversion reactor. The second function is to allow a surface distribution of the material in a homogeneous and uniform manner on the permeable bed present in the thermal conversion reactor. The third and final function is to make the connection between the preheating reactor and the thermal conversion reactor by means of this material diffuser, which can be presented for example in the form of a high temperature sleeve, so as to ensure the sealing of the process.

[0079] It should be noted that this diffuser provides a quantity of energy that the preheating reactor is not capable of providing due to the material sliding during mixing with the catalyst. This additional energy input promotes the instantaneous cracking reaction within the thermal conversion reactor.

[0080] According to one variant, the diffuser and the thermal conversion reactor are connected by a high-temperature sleeve, in order to be able to manage expansions linked to temperature differences and promote sealing between the diffuser and the thermal conversion reactor.

[0081] Advantageously, the material diffuser comprises a restriction, for example a grid or a perforated wall, which is shaped to form a pressure plug of the pasty mixture upstream of the upper inlet of the thermal conversion reactor.

[0082] In other words, the material diffuser creates, by means of the restriction, a physical barrier in the form of a pressure plug of the pasty mixture, thus preventing the supply of oxygen into the thermal conversion reactor; this restriction forming a restriction in the flow of the pasty mixture, i.e. a reduction in the flow section, and which can be formed by a grid or a perforated wall.

[0083] Alternatively, the thermal conversion installation comprises, between the preheating reactor and the material diffuser, a pump designed to send the pasty mixture into the material diffuser under a given pressure at the pump outlet.

[0084] Such a pump promotes the conveyance of the pasty mixture, due to its high viscosity, with a constant flow rate towards the material diffuser and the thermal conversion reactor, thus making it possible to overcome the pressure losses generated during conveying.

[0085] According to one characteristic, the pressure at the pump outlet is between 50 and 500 bars.

[0086] According to another feature, the thermal conversion installation comprises at least one vacuum pump connected to the preheating reactor for suction of gas included in the plastic materials and degassing of the pasty mixture inside the preheating reactor.

[0087] This vacuum pump therefore makes it possible to degas, in other words to extract the gases dissolved and / or included in the plastic materials during fluidification, and in particular the air included in the plastic materials upstream of the preheating reactor and the air incorporated in the plastic materials inside the preheating reactor during its fluidization, as well as the volatile organic compounds (VOCs) and other contaminants of the sulfur, nitrogen, oxygen, phosphorus or halogen type. The interest is twofold, namely to avoid, or at least reduce, the introduction of air inside the thermal conversion reactor, and also to remove contaminants such as volatile organic compounds (VOCs) which would harm the quality of the plastic oil.

[0088] For plastic oil to be compatible with the "Plastic to Plastic" sector, it is necessary that the molecules that compose it allow the remanufacturing of plastic of the same nature as those used to produce the oil. Plastic oil Plastic must therefore contain a low contaminant content, because excessively high levels would make the plastic oil incompatible with industrial processes for manufacturing plastic from oil. Thus, this degassing will promote the removal, before cracking, of contaminants such as volatile organic compounds and therefore contribute to an improvement in the quality of the plastic oil to be compatible with the requirements of the "Plastic to Plastic" sector.

[0089] According to one variant, the installation comprises, directly at the outlet of the preheating reactor, a screen filter having a given filtration dimension, for example between 80 and 2000 micrometers.

[0090] Such a sieve filter is indeed advantageous for extracting solid contaminants remaining present in the pasty mixture containing the fluidized plastic materials coating / encapsulating the catalyst.

[0091] In a particular embodiment, the continuous feed line for solid plastic materials comprises a compactor which is heated to a given initial temperature, which is higher than a phase transition temperature of the solid plastic materials, to compact and heat said solid plastic materials.

[0092] Advantageously, the compactor is connected to an air pump for suction of gas present inside said compactor.

[0093] Such a pump will allow extraction of the moisture present in solid plastic materials, making it possible to obtain a low water content in the final product, for example between 300 and 500 ppm and a total absence of free water. In addition, this allows the extraction of air and volatile organic compounds so as not to exceed, for example, 1000 ppm of oxygenated compounds, 50 ppm of halogenated compounds and 10 ppm for nitrogenated compounds, so as to obtain plastic oils whose quality is compatible with industrial petrochemical processes.

[0094] The invention also relates to a thermal conversion process implementing a cracking conversion of solid plastic materials into plastic oils in a thermal conversion plant as described above.

[0095] This thermal conversion process includes at least the following phases: - the solid plastic materials are continuously fed by the continuous feed line into the preheating reactor to be mixed and preheated to the preheating temperature to fluidize them, and a catalyst is continuously fed by the catalyst feed line into the preheating reactor to be mixed with the plastic materials and obtain a pasty mixture, the preheating temperature being lower than the catalyst activation temperature; - the pasty mixture is continuously transferred into the thermal conversion reactor to be heated to the pyrolysis temperature, higher than the preheating temperature and the catalyst activation temperature, under an anaerobic or inert atmosphere in order to be converted into synthesis gases and a solid reaction product containing at least chars, the pasty mixture descending by gravity inside the thermal conversion reactor and through the tubular guide which is heated to the guide temperature, before reaching the heat exchanger (80) which is heated to the cracking temperature; - the synthesis gases, containing condensable gases and non-condensable gases, are recovered at the upper outlet of the thermal conversion reactor, and the solid reaction product is recovered at the lower outlet of the thermal conversion reactor; - the condensable gases of the synthesis gases are condensed in at least one condenser into plastic oils which are recovered.

[0096] According to one characteristic, plastic materials are in the form of granules or flakes whose dimensions are at most 15 to 25 millimeters.

[0097] Advantageously, a step of degassing the pasty mixture is implemented inside the preheating reactor. [Brief description of the figures]

[0098] Other characteristics and advantages of the present invention will appear on reading the detailed description below, of a non-limiting example of implementation, made with reference to the appended figures in which: [Fig 1] is a schematic view of a thermal conversion plant comprising a thermal conversion reactor; [Fig 2] is a schematic view of a thermal conversion reactor. [Detailed description of an embodiment of the invention]

[0099] With reference to Figure 1, a thermal conversion plant 1, according to an exemplary embodiment of the invention, is provided for degradation by cracking of plastic materials for conversion of these plastic materials into plastic oils.

[0100] The thermal conversion installation 1 comprises a continuous feed line 2 for the plastic materials, which conveys the plastic materials and which comprises a conveyor 21 for conveying the plastic materials to a compactor 24.

[0101] Advantageously, the plastics are previously dry washed, for example inside an inlet centrifuge. Such an inlet centrifuge continuously receives raw and bulk plastics as input, which are in the form of granules or flakes whose dimensions are at maximum of 15 to 25 millimeters. This inlet centrifuge dry washes raw plastic materials, with the aim of decontaminating them, with air heated to a given drying temperature, for example in the order of 40 to 80 °C. This inlet centrifuge can have an evacuation for the reflux generated by the washing of plastic materials.

[0102] The conveyor 21 includes a magnetic sorting system 22 for removing ferromagnetic and ferrimagnetic metals (such as iron, nickel, cobalt) before passing into the compactor 24. These metals are in fact poisons for the catalysts and could thus degrade the quality of the plastic oils.

[0103] The compactor 24 has an inlet connected to an outlet of the conveyor 21 to receive as input the plastic materials washed and purified of ferromagnetic metals.

[0104] A gravity filter 23 may be provided on the inlet of the compactor 24, to ensure a separation function between the different densities in order to purify the plastic materials of some of the contaminants present, and mainly waste with a density greater than that of polyolefins between 0.85 and 0.95, such as for example polyethylene terephthalate containing ester functions and oxygen in large quantities and which can have a significant impact on the quality of plastic oils.

[0105] The compactor 24 is advantageously provided with a heating system for heating the plastics to a given initial temperature, which is higher than a phase transition temperature of the solid plastics, and which is for example between 120 and 200°C, and in particular between 140 and 180°C, thus making it possible to supply heat energy to the plastics promoting their phase transition from the solid state to the pasty state, while compacting them. This compacting allows extraction of moisture, air and volatile organic components present in the polymer matrices of the plastics.

[0106] Moisture extraction is advantageous to avoid the introduction of oxygen into the environment, which could lead to unwanted oxidation and combustion reactions in the polymer matrices of plastics. Extraction of volatile organic compounds is advantageous to avoid the introduction of sulfur, nitrogen, oxygen, phosphorus and halogen contaminants, in order to avoid any secondary reactions that would have a negative impact on the quality of plastic oils.

[0107] This compactor 24 has a base (in the lower part) provided with an evacuation outlet 25, as well as a suction mouth in the upper part which is connected to a suction path 26 to suck the gases into the compactor 24. Thus an extraction of air and gases escaping from the plastic materials takes place in this compactor 24, and a plug of plastic materials is formed at the base of the compactor 24, thus creating an airtight seal on the evacuation outlet 25. This compactor 24 makes it possible to reduce the quantity of air included in the plastic materials.

[0108] This suction path 26 comprises a vacuum pump T1, which provides a suction or degassing function, in order to extract dissolved gases (such as air and volatile organic compounds) in the plastics and the air included in the plastics. The vacuum pump T1 may be followed by one or more filters 28, such as for example a volatile organic compound filter (for example an activated carbon filter), for filtration and treatment of the gases sucked into the compactor. 24 before release into the atmosphere.

[0109] The thermal conversion installation 1 also comprises a catalyst supply line 4 for a continuous supply of catalyst; the catalyst having a given activation temperature, from which the catalyst is activated to promote the cracking or pyrolysis reaction of the plastics. This catalyst supply line 4 is connected to a storage volume 40 in which new catalyst is stored.

[0110] The thermal conversion plant 1 comprises a preheating reactor 3 which is continuously supplied with plastics by the continuous supply line 2, and with catalyst by the catalyst supply line 4. The plastics are introduced through a first inlet 30 of the preheating reactor 3, and the catalyst is introduced through a second inlet 37 of the preheating reactor 3. The first inlet 30 and the second inlet 37 can be separate or alternatively can be combined.

[0111] The discharge outlet 25 of the compactor 24 is connected to the first inlet 30 of the preheating reactor 3. According to an advantageous possibility, the discharge outlet 25 of the compactor 24 is arranged above the first inlet 30 of the preheating reactor 3 for feeding by gravity fall of the plastic materials.

[0112] The preheating reactor 3 comprises a heating means and a mixing means for preheating the plastic materials to a preheating temperature in order to fluidize them, and for mixing the plastic materials with the catalyst in order to obtain a pasty, miscible and homogeneous mixture, at an outlet 31 of the preheating reactor 3.

[0113] The preheating temperature is higher than a plastics fluidization temperature in order to effect a phase transition between a solid state and a pasty or viscous state. The preheating temperature is lower than the catalyst activation temperature, and is also lower than the thermal conversion temperature which corresponds to the plastics cracking temperature. The preheating temperature is for example between 180 and 290°C inside the preheating reactor 3.

[0114] Advantageously, the preheating reactor 3 comprises an endless screw 32 (or extrusion screw), and the introduction of the plastics and the catalyst takes place at a first end of this endless screw 32, and the evacuation of the pasty mixture takes place at a second end of this endless screw 32, opposite its first end. Preferably, the mixing during extrusion takes place at constant pressure. It is in this endless screw 32 that the homogenization of the plastics coming from the compactor 24 with the catalyst takes place. It is advantageous for the length of the endless screw 32 to be at least 10, or even 15, times greater than the diameter of the endless screw 32, to improve homogenization, that is to say a uniform distribution of the catalyst within the plastics.It is also advantageous to work in the preheating reactor 3 with a temperature gradient, which increases from the first end to the second end of the worm screw 32, to promote a progressive phase transition and avoid structural degradation of the plastic materials.

[0115] The heat input into the preheating reactor 3, with a preheating temperature above 140°C (or even above 180°C) promotes the miscibility of the components and provides a significant energy input in order to reduce the energy consumed in the thermal conversion reactor 5 so that a flash cracking reaction can occur inside this thermal conversion reactor 5.

[0116] This preheating reactor 3 is connected to a vacuum pump 33 which provides a degassing function, in order to extract dissolved gases (such as air and volatile organic compounds) in the plastics and the air included in the plastics upstream of the preheating reactor 3 and during fluidization.

[0117] The vacuum pump 33 may be followed by a water tank 34 at a temperature of between 5 and 15°C, and preferably of the order of 10°C, making it possible to create a partial vacuum for the operation of the vacuum pump 33 and to trap in the water the volatile organic compounds extracted by this vacuum pump 33.

[0118] Alternatively, the vacuum pump 33 may be followed by one or more filters, such as for example a volatile organic compound filter (for example an activated carbon filter), for filtration and treatment of gases dissolved and included within the plastic materials before release into the atmosphere.

[0119] Advantageously, the preheating reactor 3 comprises at its outlet 31 a mesh filter 35, such as an automatic and self-cleaning mesh filter, offering a mesh size of between 80 and 2000 micrometers, making it possible to filter out the remaining impurities such as certain solid contaminants, such as for example wood.

[0120] This mesh filter 35 can also be connected to a vacuum pump 36 which makes it possible to extract gases (such as air and volatile organic compounds) in the plastics. Indeed, the pressure exerted by the mesh filter 35 on the pasty mixture can still release harmful volatile organic compounds which are detrimental to the quality of the plastic oils.

[0121] This vacuum pump 36 may be followed by one or more filters 37, such as for example a volatile organic compound filter (for example an activated carbon filter), for filtration and treatment of gases dissolved and included within the plastic materials before release into the atmosphere.

[0122] The thermal conversion installation 1 comprises a material diffuser 10, connected to the outlet 31 of the preheating reactor 3, so that the pasty mixture (comprising, as a reminder, the fluidized plastic materials mixed with the catalyst), is introduced into the material diffuser 10.

[0123] The function of this material diffuser 10 is to ensure a substantially homogeneous and uniform surface distribution of the pasty mixture at its outlet 11. The material diffuser 10 is heated to a diffusion temperature greater than or equal to the preheating temperature and less than the cracking (or pyrolysis) temperature, in order to maintain the pasty mixture in a viscous state and to transfer heat energy to the plastics and the catalyst. This diffusion temperature may be between 200 and 300°C.

[0124] Advantageously, the thermal conversion installation 1 comprises, between the outlet 31 of the preheating reactor 3 and the material diffuser 10, an injection pump 12 designed to send the pasty mixture into the material diffuser under a given pressure at the outlet of the pump 12; said pressure at the outlet of the pump 12 being able to be between 50 and 500 bars. It is advantageous to connect the pump 12 to the material diffuser 10 by means of a thermo-regulated tube at a temperature between 200 and 300°C.

[0125] The thermal conversion installation 1 also comprises, downstream or at the outlet of the preheating reactor 3, a flow meter 13 for measuring a mass or volumetric flow rate of the pasty mixture. In the example illustrated, the flow meter 13 is positioned between the outlet 31 of the preheating reactor 3 and the material diffuser 10, and in particular after the pump 12.

[0126] The thermal conversion installation 1 comprises a thermal conversion reactor 5 connected to the outlet 11 of the material diffuser 10; this thermal conversion reactor 5 is therefore arranged downstream of the preheating reactor 3 and is configured to heat the pasty mixture to a cracking temperature higher than the preheating temperature and the activation temperature of the catalyst, under an anaerobic or inert atmosphere in order to convert this pasty mixture into synthesis gases and a solid reaction product containing at least chars and catalyst. Inside the thermal conversion reactor 5, an anaerobic and continuous cracking reaction of the plastics occurs, promoted by the catalyst.

[0127] This thermal conversion reactor 5 will be described in more detail later, with reference to Figure 2.

[0128] The thermal conversion reactor 5 internally incorporates a heat exchanger 50 which forms a fixed bed. The pyrolysis or cracking reaction therefore takes place between the plastics and the catalyst during contact with the heat exchanger 50 heated within the thermal conversion reactor 5, in an anaerobic or inert atmosphere and with a fixed and stable cracking temperature, for example between 300 and 900°C. This reaction leads to cracking and therefore depolymerization of the plastics.

[0129] This thermal conversion reactor 5 is therefore heated (for example electrically heated) internally and also advantageously externally, allowing the conversion of the polymer matrices of the plastics into synthesis gas in anaerobic and isothermal conditions. The cracking reaction takes place between the homogeneous pasty mixture of the polymer matrices in which the catalysts are encapsulated / coated. The thermal conversion reactor 5 allows the cracking reaction by breaking the carbon-carbon bonds at the cracking temperature which is fixed (to be in isothermal conditions), this cracking temperature being in a working range of between 300 and 600°C, preferably between 400 and 500°C, and very preferably between 450°C and 480°C favorable to obtaining a plastic oil comprising light chains from C5 to C17.

[0130] The thermal conversion reactor 5 has an upper outlet 51 located above the heat exchanger 50 for the evacuation and recovery of the synthesis gases, and a lower outlet 52 located below the heat exchanger 50 for evacuation and recovery of the solid reaction products. The lower outlet 52 is provided at the base of the thermal conversion reactor 5, in the lower part of the thermal conversion reactor 5.

[0131] The synthesis gases therefore exit at the upper outlet 51 which is above the heat exchanger 50 in order to promote the settling of the chars within the thermal conversion reactor 5, with the aim of avoiding the transfer of the chars to the upper outlet 51 and thus not contaminating the synthesis gases.

[0132] The outlet 11 of the material diffuser 10 is connected to the top of the thermal conversion reactor 5 on a high inlet 53 (in other words in the upper part of the thermal conversion reactor 5) and this material diffuser 10 provides a substantially homogeneous and uniform surface distribution of the pasty mixture inside the thermal conversion reactor 5 and on the heat exchanger 50. Advantageously, the connection between the material diffuser 10 and the thermal conversion reactor 5 is made using a high temperature sleeve, in order to be able to manage the expansions linked to the temperature differences between the material diffuser 10 and the thermal conversion reactor 5, and thus preserve the seal.

[0133] Advantageously, the material diffuser 10 comprises a restriction 14, for example a grid or a perforated wall, which is shaped to form a pressure plug of the pasty mixture upstream of the upper inlet 53 of the thermal conversion reactor 5.

[0134] The thermal conversion installation 1 comprises a solid reaction product recovery line 6 connected to the lower outlet 52 of the thermal conversion reactor 5 to recover and treat the solid reaction product which, as a reminder, comprises at least the chars and the catalyst; the catalyst, having participated in the cracking reaction, is at least partially in a used state, in other words it comprises catalyst to be regenerated and, in a smaller proportion, new or unused catalyst.

[0135] This solid reaction product recovery line 6 comprises a regeneration reactor 60 connected to the lower outlet 52 of the thermal conversion reactor 5, where this regeneration reactor 60 recovers the solid reaction product to heat it to a regeneration temperature allowing at least partial regeneration of the catalyst it contains. This regeneration reactor 60 therefore has the following functions: function of regenerating the used catalyst contained in the solid reaction product at the outlet of the thermal conversion reactor 5, with the aim of being able to reuse it.

[0136] This regeneration reactor 60 is a closed reactor, also called a “batch” reactor. The regeneration temperature is for example between 300 and 900°C, and in particular between 600 and 800°C, to regenerate the catalyst and separate the regenerated catalyst and the chars.

[0137] Since this regeneration reactor 60 is a closed reactor, and since the solid reaction product continuously leaves the thermal conversion reactor 5, it is advantageous to use a buffer volume 61 between the lower outlet 52 of the thermal conversion reactor 5 and the regeneration reactor 60. This buffer volume 61 makes it possible to isolate the continuous work of the thermal conversion reactor 5 and the work cycles of the regeneration reactor 60.

[0138] This buffer volume 61 can thus be framed by two valves 62 (thus forming a bimetallic slide) whose openings are carried out in turn in order to allow the solid reaction products to be conveyed to the regeneration reactor 60, while preventing any entry of air into the thermal conversion reactor 5. The first valve 62 allows the entry of the solid reaction products into the buffer volume 61 and the second valve 62 allows their evacuation. When the second valve is opened for the purpose of evacuating the solid reaction products, the first valve 62 is closed; and vice versa. The openings and closings of the valves 62 are advantageously managed by the level of the solid reaction products present inside the buffer volume 61. The evacuation of the solid reaction products is carried out cyclically.

[0139] Advantageously, the buffer volume 61 is connected to an inert gas introduction system 64 in order to sweep the gases and inert the installation 1 to work in an anaerobic atmosphere.

[0140] This regeneration reactor 60 comprises a double jacket in which a heat transfer fluid is present or circulates, heated for example by a burner; this burner is thus adjusted to heat the heat transfer fluid of the regeneration reactor 60 to the regeneration temperature.

[0141] It is also advantageous for the solid reaction product recovery line 6 to comprise, at the outlet of the regeneration reactor 60, a separator for separating the regenerated catalyst from the chars or a mixture containing the chars and non-regenerated catalyst. The chars and the non-regenerated catalyst can be collected for possible further processing.

[0142] The thermal conversion installation 1 comprises a return line 41 connecting the outlet of the regeneration reactor 60 to the catalyst supply line 4 in order to reintroduce the regenerated catalyst inside the preheating reactor 3. More precisely, the return line 41 is part of the catalyst supply line 4, and this return line 41 connects the first outlet 62 of the separator 61 to the second inlet 37 of the preheating reactor 3, in order to introduce the regenerated catalyst inside the preheating reactor 3.

[0143] To the extent that the catalyst is not fully regenerated in the regeneration reactor 60 and / or is not fully separated and recovered at the outlet of the separator, the return line 41 is connected to the storage volume 40 for new catalyst in order to mix the regenerated catalyst and the new catalyst before introduction into the preheating reactor 3.

[0144] The catalyst supply line 4 thus comprises a metering system such as a metering screw 42 for metering and mixing the new catalyst with the regenerated catalyst in a predefined and controlled proportion. This metering screw 42 is for example a gravimetric metering screw.

[0145] Advantageously, the metering screw 42 is connected to the flow meter 13 and is shaped to regulate a metering of a quantity of catalyst continuously introduced into the preheating reactor 3 as a function of the mass or volumetric flow rate of the pasty mixture. In other words, the metering screw 42 is speed-controlled as a function of this flow rate, in order to ensure a constant catalyst rate relative to the flow rate of the pasty mixture. The precision of this catalyst metering impacts the quality of the plastic oils, the length, the structure and the proportion of the carbon chains.

[0146] The thermal conversion plant 1 comprises a synthesis gas recovery line 7 connected to the upper outlet 51 of the thermal conversion reactor 5, the synthesis gases containing condensable gases and non-condensable gases. This synthesis gas recovery line 7 is thermally traced at the same temperature as that of the thermal conversion reactor 5, in order to avoid premature condensation of the condensable gases into plastic oils.

[0147] The synthesis gas recovery line 7 comprises at least one condenser 71 shaped to at least partially condense the condensable gases of the synthesis gases into plastic oils; this condenser 71 operating at a given cooling temperature, for example between 0 and 10°C and in particular of the order of 4°C in order to condense the short chains. The condenser 71 can be cooled using a water and / or ethylene glycol circuit at the cooling temperature.

[0148] A thermal shock is necessary between the hot synthesis gases and the condenser(s) 71 for the condensation phenomenon to take place. This step of the process results in condensation of the polymer chains present in the synthesis gases, in the form of plastic oil and a fraction of water. The proportions of condensing gases are controlled by controlling the cooling temperature of the condenser(s) 71.

[0149] The synthesis gas recovery line 7 comprises, at the outlet of the condenser 71, a settling tank 72 for settling the plastic oils and possibly the condensed water, resulting from the condensation in the condenser 71. In this settling tank 72, the solid contaminants fall by gravity to the bottom of the settling tank 72, thus making it possible to separate the plastic oils from these solid contaminants. A storage tank 73 is connected to the bottom of the settling tank 72, via a valve, in order to recover and store these solid contaminants.

[0150] The synthesis gas recovery line 7 comprises a non-condensable gas recovery pipe 74, connected to the upper part of the settling tank 72 to recover the non-condensable gases. This non-condensable gas recovery pipe 74 can be connected to a burner or to a cogeneration plant 75 to convert the heat energy of the non-condensable gases into thermal energy and electricity in order to thermally and electrically supply the thermal conversion installation 1. Any excess energy can be used to supply mechanical recycling (hybrid recycling) and / or be marketed on the networks.

[0151] The synthesis gas recovery line 7 comprises a homogenization tank 76 connected to the settling tank 72 to recover the plastic oils and thus bring together the different fractions of the plastic oils, arriving from the settling tank 72, to carry out homogenization of the plastic oils before their storage in an oil storage tank 77. The homogenization tank 76 is advantageously equipped with one or more rotating stirring blades.

[0152] It should be noted that all steps of the conversion process are carried out in an anaerobic atmosphere (in the absence of oxygen). Inerting cycles (with nitrogen or other inert gases) can advantageously be carried out in the various elements of the thermal conversion plant 1, in order to expel all the oxygen present in the plastics and in the catalyst, and to evacuate the remaining synthesis gases in the thermal conversion plant 1.

[0153] The remainder of the description relates to the thermal conversion reactor 5 illustrated in Figure 2.

[0154] This thermal conversion reactor 5 comprises a reaction chamber 50 having: - an upper wall 54 on which the upper inlet 53 is provided for introducing the pasty mixture (formed from a mixture of fluidized plastic materials and the catalyst); - a lower wall 55 on which the lower outlet 52 is provided for evacuating solid reaction products; and - a peripheral wall 56 of tubular shape (and for example of cylindrical shape) extending between the upper wall 54 and the lower wall 55 over an enclosure height HE measured along a central axis X; this central axis X being vertical.

[0155] It is possible to provide a pressure probe in order to measure and monitor the pressure inside the reaction chamber 50.

[0156] The thermal conversion reactor 5 comprises a thermal cracking device 8 comprising: - a heat exchanger 80 arranged inside the reaction chamber 50 so that an annular space is provided between the heat exchanger 80 and the peripheral wall 56; and - a main heating system 81 coupled to the heat exchanger 80 to heat it to the cracking temperature.

[0157] This heat exchanger 80 is made of a refractory metal alloy or ceramic, and it has an upper section 82 having a conical, ovoidal, pyramidal or hemispherical shape centered on the central axis X and ending in a top 83 arranged opposite and below the upper inlet 53. The upper section 82 has a base 84, this upper section 82 narrowing from its base 84 to its top 83; in other words the diameter of the upper section 82 decreases from the base 84 to the top 83, and the upper section 82 has a maximum diameter at its base 84. The top 83 of the heat exchanger 80 is advantageously rounded.

[0158] The conical shape is illustrated in Figure 2, and it is advantageous for the taper angle to be between 10 and 80°, and preferably between 10 and 30° and for example 20°, in order to promote the flow of the raw material on the peripheral surface of the cone.

[0159] The geometry of this upper section 82 allows recirculation of the synthesis gases generated as well as recovery by gravity of the reaction products. solids (such as chars and deactivated catalysts). This decantation is intended to prevent deposits and aggregation of solid reaction products on the peripheral surface of the upper section 82, which could lead to a limitation of the exchange surfaces available for the cracking reactions of the polymer matrices in contact with the catalysts. In addition, this geometry makes it possible to prevent the transport by the synthesis gases of chars and deactivated catalysts towards the upper outlet 51 which could cause contamination of the plastic oils.

[0160] This upper section 82 of the heat exchanger 80 has a height HS, measured from its base 84 to its top 83 along the central axis X, and this height HS is between 0.1 and 0.5 times the enclosure height HE, and for example between 0.20 and 0.25 times the enclosure height HE.

[0161] Furthermore, the peripheral wall 56 of the reaction chamber 50 has an internal diameter DP, and the upper section 82 of the heat exchanger 80 has a maximum diameter or a maximum transverse dimension DM which is between 0.5 and 0.9 times the internal diameter DP, and for example between 0.7 and 0.8 times the internal diameter DP.

[0162] This heat exchanger 80 has, in the extension of the upper section 82, a lower section 85 which is for example of cylindrical shape. This lower section 85 therefore extends the upper section 82 downwards, beyond its base 84. The lower section 85 has a diameter corresponding to the maximum diameter of the upper section 82, in other words the diameter at the base 84.

[0163] The heat exchanger 80 is monobloc, so that the upper section 82 and the lower section 85 are made in one piece.

[0164] The heat exchanger 80 has an overall height HG measured along the central axis, which corresponds to the combined height of the upper section 82 and the lower section 85, and this overall height HG is between 0.2 and 0.5 times the enclosure height HE, and for example between 0.35 and 0.45 times the enclosure height HE.

[0165] The thermal conversion reactor 5 has the upper outlet 51 for recovery of the synthesis gases, this upper outlet 51 being arranged on the peripheral wall 56 of the reaction enclosure 50, above the top 83 of the heat exchanger 80.

[0166] It is possible to have a temperature probe 94 at the high outlet 51 in order to measure and monitor the temperature of the synthesis gases leaving the thermal conversion reactor 5.

[0167] The thermal conversion reactor 5 comprises a tubular guide 57 extending inside the reaction enclosure 50 from the upper wall 54 on a given HT guide height. This HT guide height is between 0.1 and 0.5 times the HE enclosure height, and for example between 0.30 and 0.35 times the HE enclosure height.

[0168] The tubular guide 57 extends the upper inlet 53, so that the upper inlet 53 is surrounded by this tubular guide 57. This tubular guide 57 is centered on the central axis X, in alignment with the upper section 82 of the heat exchanger 80. The tubular guide 57 has a free termination 58 located at a given non-zero distance DT from the top 83 of the heat exchanger 80. This distance DT is between 0.05 and 0.3 times the enclosure height HE.

[0169] The free termination 58 is therefore located above and opposite this top 83. Furthermore, this free termination 58 has a mouth having a dimension (for example a diameter if the tubular guide 57 is cylindrical) which is greater than or equal to a diameter of the top 83 of the heat exchanger 80. Thus, the pasty mixture enters through the upper inlet 53, is guided into the tubular guide 57, flowing inside this tubular guide 57, and then it flows and falls onto the top 83 of the heat exchanger 80.

[0170] The free end 58 of the tubular guide 57 is located below the upper outlet 51; in other words, this upper outlet 51 is arranged above the free end 58 of the tubular guide 57. Thus, this upper outlet 51 faces the tubular guide 57, so that the synthesis gases rise from the heat exchanger 80 (cracking zone) and rise around the tubular guide 57 before reaching the upper outlet 51. In this way, the synthesis gases are separated from the pasty mixture which flows inside the tubular guide 57.

[0171] The tubular guide 57 is advantageously coupled to a secondary heating system 570 to heat it to a predefined guide temperature which is equivalent to the cracking temperature; either the guide temperature is equivalent to the cracking temperature, or the guide temperature is equivalent to the cracking temperature to within 5%. A temperature probe 91 is provided to measure the temperature in the tubular guide 57, in order to be able to control or regulate it at the guide temperature (in other words at the cracking temperature).

[0172] The integration of the plastic materials within the thermal conversion reactor 5 is therefore done by this tubular guide 57 which will promote the flow and direction of the material towards the heat exchanger 80, and therefore towards the cracking zone. This tubular guide 57 is thus heated to the cracking temperature in order to provide maximum energy in isothermal conditions allowing the energies to be lowered necessary for cracking during contact between the polymer matrices of the plastics and the heat exchanger 80. It should be noted that the degradation of the material taking place at more than 300°C is no longer a problem in this zone because the pasty mixture is inside the thermal conversion reactor 5, therefore in an anaerobic environment and allowing the extraction of synthesis gases.

[0173] In addition, an oxygen-free environment, called anaerobic, is advantageous in order to avoid uncontrolled oxidation reactions which could lead to the formation of undesired incondensable gases, in quantities greater than the condensable gases, directly impacting the quality of the plastic oils. Finally, an anaerobic environment makes it possible to avoid any involuntary combustion of the raw material. Thus, inerting cycles (with nitrogen or other inert gases) can be carried out via the lower outlet 52 at each start-up of the installation 1, in order to expel all the oxygen present in the thermal conversion reactor 5.

[0174] Advantageously, the thermal conversion reactor 5 has a total volume delimited by the upper wall 54, the lower wall 55 and the peripheral wall 56, and a sub-volume of the thermal conversion reactor 5, located around the heat exchanger 80 and between the upper wall 54 and the base 84 of the upper section 82 of the heat exchanger 80, is between 0.4 and 0.9 times the total volume.

[0175] This sub-volume forms a thermal agitation zone in which the synthesis gases circulate and are agitated. This thermal agitation zone, present between the cracking zone and the upper outlet, allows homogenization of the synthesis gases and the termination of the depolymerization reactions before extraction of the synthesis gases towards the condenser. The management of its volume, between 0.4 and 0.9 times the total volume, provides precise management of the residence time of the synthesis gases and thus management of the lengths of the molecular chains and the molecular reactions that take place there.

[0176] It is advantageous to provide a temperature probe 92 to measure the temperature in this sub-volume (for example between the top 83 of the heat exchanger 80 and the free end 58 of the tubular guide 57), in order to be able to control or regulate it at the cracking temperature.

[0177] The heat exchanger 80 is mounted on a support 87 fixed to the reaction chamber 80, so that the heat exchanger 80 is located at a distance from the lower wall 55, thus leaving a volume under the heat exchanger 80 for the solid reaction products. In the example illustrated, the support 87 is fixed to the lower wall 55.

[0178] This volume forms a storage area for solid reaction products, and it is advantageous to provide a temperature probe 93 to measure the temperature in the volume, in order to be able to monitor it.

[0179] The heat exchanger 80 is hollow and has an internal orifice 86, which is a blind hole, and the main heating system 81 comprises at least one regulated electrical resistor 88 arranged inside this internal orifice 86. Thus, a hole 59 is provided in the lower wall 55 and the support 87 is tubular to allow the passage of the electrical resistor and / or an electrical power supply cable 89 used to electrically supply the at least one electrical resistor 88.

Claims

CLAIMS 1. Thermal conversion reactor (5) for conversion by cracking, under an anaerobic or inert atmosphere, of plastic materials into synthesis gases condensable at least partially into plastic oils, and into solid reaction products, said thermal conversion reactor (5) comprising: - a reaction chamber (50) having a top wall (54) on which a top inlet (53) is provided for introducing plastic materials, a bottom wall (55) on which a bottom outlet (52) is provided for discharging solid reaction products, and a peripheral wall (56) extending between the top wall (54) and the bottom wall (55) over a chamber height (HE) measured along a central axis (X); - a thermal cracking device (8) comprising a heat exchanger (80) arranged inside the reaction chamber (50) so that an annular space is provided between the heat exchanger (80) and the peripheral wall (56), said heat exchanger (80) having an upper section (82) having a conical, ovoidal, pyramidal or hemispherical shape centered on a central axis (X) and ending in a top (83) arranged opposite and below the upper inlet (53), said thermal cracking device (8) comprising a main heating system (81) coupled to the heat exchanger (80) to heat it to a predefined cracking temperature; - an upper outlet (51) for recovery of synthesis gases, arranged above the top (83) of the heat exchanger (80); - a tubular guide (57) extending the upper inlet (53) and extending inside the reaction chamber (50) from the upper wall (54) over a guide height (HT), said tubular guide (57) having a free termination (58) located at a given non-zero distance (DT) from the top (83) of the heat exchanger (80); and - a secondary heating system (570) coupled to the tubular guide (57) to heat it to a predefined guide temperature.

2. Thermal conversion reactor (5) according to claim 1, wherein the upper outlet (51) is arranged above the free end (58) of the tubular guide (57).

3. Thermal conversion reactor (5) according to claim 1 or 2, wherein the guide temperature is equivalent to the cracking temperature, plus or minus 5%.

4. Thermal conversion reactor (5) according to any one of the preceding claims, in which the guide height (HT) is between 0.1 and 0.5 times the enclosure height (HE), and for example between 0.30 and 0.35 times the enclosure height (HE).

5. Thermal conversion reactor (5) according to any one of the preceding claims, in which the distance (DT) between the free end (58) of the tubular guide (57) and the top (83) of the heat exchanger (80) is between 0.05 and 0.3 times the enclosure height (HE).

6. Thermal conversion reactor (5) according to any one of the preceding claims, in which the tubular guide (57) is centered on the central axis (X), in alignment with the upper section (82) of the heat exchanger (80), of conical, ovoidal, pyramidal or hemispherical shape.

7. Thermal conversion reactor (5) according to any one of the preceding claims, in which the free end (58) of the tubular guide (57) has a mouth having a dimension greater than or equal to a diameter of the top (83) of the heat exchanger (80).

8. Thermal conversion reactor (5) according to any one of the preceding claims, in which the upper section (82) of the heat exchanger (80) has a base (84), this upper section (82) narrowing from its base (84) to its top (83), and the heat exchanger (80) has, in the extension of the base (84) of the upper section (82), a lower section (85), for example of cylindrical shape.

9. Thermal conversion reactor (5) according to claim 8, wherein the thermal conversion reactor (5) has a total volume delimited by the upper wall (54), the lower wall (55) and the peripheral wall (56), and wherein a sub-volume of the thermal conversion reactor (5), located around the heat exchanger (80) and between the upper wall (54) and the base (84) of the upper section (82) of the heat exchanger (80), is between 0.4 and 0.9 times the total volume.

10. Thermal conversion reactor (5) according to claim 8 or 9, in which the upper section (82) of the heat exchanger (80), of conical, ovoidal, pyramidal or hemispherical shape, has a height (HS) measured along the central axis (X) from its base (84) to its top (83), and which is between 0.1 and 0.5 times the enclosure height (HE), and for example between 0.20 and 0.25 times the enclosure height (HE).

11. Thermal conversion reactor (5) according to any one of claims 8 to 10, in which the heat exchanger (80) has an overall height (HG) measured along the central axis (X) and which corresponds to a combined height of the upper section (82) and the lower section (85), and this overall height (HG) is between 0.2 and 0.5 times the enclosure height (HE), and for example between 0.35 and 0.45 times the enclosure height (HE).

12. Thermal conversion reactor (5) according to any one of the preceding claims, wherein the heat exchanger (80) is hollow and has an internal orifice (86), and the main heating system (81) comprises at least one regulated electrical resistance (88) arranged inside said internal orifice (86).

13. Thermal conversion reactor (5) according to any one of the preceding claims, wherein the top (83) of the heat exchanger (80) is rounded.

14. Thermal conversion reactor (5) according to any one of the preceding claims, in which the peripheral wall (56) of the reaction enclosure (50) has an internal diameter, and the upper section (82) of the heat exchanger (80), of conical, ovoidal, pyramidal or hemispherical shape, has a maximum diameter or a maximum transverse dimension which is between 0.5 and 0.9 times the internal diameter, and for example between 0.7 and 0.8 times the internal diameter.

15. Thermal conversion reactor (5) according to any one of the preceding claims, in which the heat exchanger (80) is mounted on a support (87) fixed to the reaction enclosure (50), so that the heat exchanger (80) is located at a distance from the lower wall (55).

16. Thermal conversion reactor (5) according to any one of the preceding claims, in which the heat exchanger (80) is made of a refractory metal alloy or ceramic.

17. Thermal conversion plant (1) for cracking conversion of solid plastic materials into plastic oils, said thermal conversion plant (1) comprising at least: - a continuous supply line (2) for solid plastic materials; - a catalyst supply line (4); - a preheating reactor (3) connected to the continuous supply line (2) of solid plastic materials and to the catalyst supply line (4), said preheating reactor (3) being configured to mix the solid plastic materials and preheat them to a preheating temperature in order to fluidize them, and to mix the fluidized plastic materials with the catalyst in order to obtain at an outlet (31) a pasty mixture, the preheating temperature being lower than an activation temperature of the catalyst; - a thermal conversion reactor (5) according to any one of the preceding claims, said thermal conversion reactor (5) having its upper inlet (53) in sealed fluid communication with the outlet (31) of the preheating reactor (3), for a gravity flow of the pasty mixture onto the upper section (82) of the heat exchanger (80) and a heating of the pasty mixture to the cracking temperature, which is higher than the preheating temperature and the activation temperature of the catalyst, under an anaerobic or inert atmosphere in order to be converted into synthesis gases condensable at least partially into plastic oils, and solid reaction products; - a synthesis gas recovery line (7) connected to the upper outlet (51) of the thermal conversion reactor (5), the synthesis gases containing at least condensable gases, said synthesis gas recovery line comprising at least one condenser (71) shaped to at least partially condense the condensable gases of the synthesis gases into plastic oils; and - a solid reaction product recovery line (6) connected to the lower outlet (52) of the thermal conversion reactor (5).

18. Thermal conversion installation (1) according to claim 17, comprising, downstream or at the outlet of the preheating reactor (3), a flow meter (13) for measuring a mass or volumetric flow rate of the pasty mixture, and the catalyst supply line (4) comprises a dosing system (42) connected to the flow meter (13) and shaped to regulate a dosage of a quantity of catalyst continuously introduced into the preheating reactor (3) as a function of the mass or volumetric flow rate of the pasty mixture.

19. Thermal conversion installation (1) according to claim 17 or 18, comprising, between the preheating reactor (3) and the thermal conversion reactor (5), a material diffuser (10) for a substantially homogeneous and uniform surface distribution of the pasty mixture on the upper inlet (53) of the thermal conversion reactor (5), said material diffuser (10) being heated to a diffusion temperature higher than the preheating temperature and lower than the cracking temperature.

20. Thermal conversion installation (1) according to claim 19, in which the material diffuser (10) comprises a restriction (14), for example a grid or a perforated wall, which is shaped for formation of a pressure plug of the pasty mixture upstream of the high inlet (53) of the thermal conversion reactor (5).

21. Thermal conversion installation (1) according to claim 19 or 20, comprising, between the preheating reactor (3) and the material diffuser (10), a pump (12) designed to send the pasty mixture into the material diffuser (10) under a given pressure at the outlet of the pump.

22. Thermal conversion installation (1) according to claim 21, in which the pressure at the outlet of the pump is between 50 and 500 bars.

23. Thermal conversion installation (1) according to any one of claims 17 to 22, comprising at least one vacuum pump (33) connected to the preheating reactor (3) for suction of gas included in the plastic materials and degassing of the pasty mixture inside the preheating reactor (3).

24. Thermal conversion plant (1) according to any one of claims 17 to 23, wherein the continuous feed line (2) of the solid plastic materials comprises a compactor (24) which is heated to a given initial temperature, which is higher than a phase transition temperature of the solid plastic materials, to compact and heat said solid plastic materials.

25. A thermal conversion process implementing a cracking conversion of solid plastic materials into plastic oils in a thermal conversion plant according to any one of claims 17 to 24, said thermal conversion process comprising at least the following phases: - the solid plastic materials are continuously fed by the continuous feed line (2) into the preheating reactor (3) in order to be mixed and preheated to the preheating temperature to fluidize them, and a catalyst is continuously fed by the catalyst feed line (4) into the preheating reactor (3) to be mixed with the plastic materials and obtain a pasty mixture, the preheating temperature being lower than the activation temperature of the catalyst; - the pasty mixture is continuously transferred into the thermal conversion reactor (5) to be heated to the pyrolysis temperature, higher than the preheating temperature and the catalyst activation temperature, under an anaerobic or inert atmosphere in order to be converted into synthesis gases and a solid reaction product containing at least chars, the pasty mixture descending by gravity inside the thermal conversion reactor (5) and through the tubular guide (57) which is heated to the guide temperature, before reaching the heat exchanger (80) which is heated to the cracking temperature; - the synthesis gases, containing condensable gases and incondensable gases, are recovered at the upper outlet (51) of the thermal conversion reactor (5), and the solid reaction product is recovered at the lower outlet (52) of the thermal conversion reactor (5); - the condensable gases of the synthesis gases are condensed in the at least one condenser (71) into plastic oils which are recovered.

Images