Process and installation for catalytically converting plastic materials into pyrolytic oils

Abstract

The invention relates to a process for converting plastic materials into pyrolytic oils, wherein: - the plastic materials are continuously fed into a preheating reactor (3) in order to be mixed and preheated at a preheating temperature to obtain a pasty mixture; - the pasty mixture is continuously transferred into a pyrolysis reactor (5) to be heated at a pyrolysis temperature, under an anaerobic or inert atmosphere, in order to be converted into synthesis gases and a solid reaction product; - the synthesis gases, containing condensable gases and uncondensable gases, are recovered on a first outlet (51) located above the permeable bed, and the solid reaction product is recovered on a second outlet (52) located below the permeable bed; - the condensable gases of the synthesis gases are condensed into pyrolytic oils which are recovered.

Description

[0001] DESCRIPTION

[0002] PROCESS AND PLANT FOR CATALYTIC CONVERSION OF PLASTICS INTO PYROLYTIC OILS

[0003] [Technical field]

[0004] The invention relates to a conversion process implementing pyrolysis degradation of plastic materials for conversion into pyrolytic oils, as well as to an associated conversion installation.

[0005] It relates more particularly to a process using catalytic and / or thermal pyrolysis for the chemical recycling of plastic materials, making it possible to produce pyrolytic oils by condensation of the synthesis gases obtained during the catalytic and / or thermal pyrolysis reaction.

[0006] The invention thus finds a preferred, and non-limiting, application for the recycling of plastic materials, and in particular plastic waste, in order to produce pyrolytic oils which will make it possible to produce plastic, thus placing the invention in a so-called “Plastic to Plastic” sector, in other words in a circular economy of plastics.

[0007] [State of the art]

[0008] As is known, there are different processes such as gasification, pyrolysis, solvolysis and depolymerization, to degrade plastics, in order to obtain chemical products with lower molar masses, such as pyrolytic oils. Pyrolysis consists of a degradation, or cracking, of polymer molecules subjected to a high temperature (generally between 300 and 900°C) to obtain smaller molecules, in the absence of oxygen, with a catalyst (so-called catalytic pyrolysis) or without a catalyst (so-called thermal pyrolysis).

[0009] However, there is a need to carry out catalytic and / or thermal pyrolysis for the production of pyrolytic oils on an industrial scale and continuously, without transient conditions likely to harm the quality of the pyrolytic oils.

[0010] [Summary of the invention]

[0011] Also, an aim of the invention is to propose a method and a conversion installation which allow continuous operation for the production of qualitative pyrolytic oils from a heterogeneous quality of plastic materials.

[0012] To this end, the invention proposes a conversion process implementing degradation by pyrolysis of plastic materials for conversion into pyrolytic oils, this conversion process comprising at least the following phases:

[0013] - the plastic materials are continuously fed into a preheating reactor in order to be mixed and preheated to a preheating temperature to fluidize them, and a catalyst is continuously fed into the preheating reactor to be mixed with the plastic materials and obtain a pasty mixture, the preheating temperature being lower than an activation temperature of the catalyst;

[0014] - the pasty mixture is continuously transferred into a pyrolysis reactor to be heated to a 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 pyrolysis reactor and through a permeable bed which is heated to the pyrolysis temperature;

[0015] - the synthesis gases, containing condensable gases and non-condensable gases, are recovered at a first outlet of the pyrolysis reactor located above the permeable bed, and the solid reaction product is recovered at a second outlet of the pyrolysis reactor located below the permeable bed;

[0016] - the condensable gases from the synthesis gases are condensed into pyrolytic oils which are recovered.

[0017] Thus, the invention proposes to preheat the plastic materials to the preheating temperature, while mixing them with the catalyst, then to heat and crack the fluidized plastic materials to the pyrolysis temperature continuously.

[0018] 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 pyrolysis 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 permeable bed having a large heat exchange surface with the plastics falling (or flowing) by gravity through this permeable bed.

[0019] 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.

[0020] 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 pyrolysis 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.

[0021] 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 higher molecular weight, and therefore improve the quality of the pyrolytic oil in accordance with the requirements of the “Plastic to Plastic” sector.

[0022] The catalyst activation temperature is the temperature at which the catalyst is activated and chemically promotes the pyrolysis reaction.

[0023] The catalyst, for example of the zeolite type, makes it possible to reduce the working temperatures in the pyrolysis reactor and the activation energies necessary to trigger the pyrolysis or 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 pyrolysis 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.

[0024] The introduction of plastics and the catalyst, in a pasty state and homogeneously mixed, into the pyrolysis reactor makes it possible to optimize contact with the heated permeable bed which provides the energy capacity triggering the cracking reaction of the plastics into synthesis gas (also called "syngas").

[0025] It should be noted that the pyrolysis reaction occurs in an anaerobic atmosphere (in the absence of oxygen) or in an inert atmosphere, with a fixed and stable pyrolysis temperature. This pyrolysis reaction takes place during the simultaneous contact of the fluidized plastics, mixed with the catalyst, and the heated permeable bed within the pyrolysis reactor, leading to the chemical cracking reaction and therefore the depolymerization of the plastics. The use of a pyrolysis 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 permeable bed.

[0026] This process 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 pyrolysis 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 pyrolysis reactor and therefore to obtain a selective cutting of the carbon chains present within the pyrolysis oils.

[0027] Thus, the process allows to have:

[0028] - a first input of activation energy, in the preheating reactor, over a temperature range between 20 and 290°C, at a rate of 40 to 70% of the total energy required to carry out the pyrolysis reaction; and

[0029] - a second input of activation energy, in the pyrolysis reactor, over a temperature range between 300 and 900°C, at a rate of 30 to 60% of the energy required to trigger the pyrolysis reaction.

[0030] Thus, a large amount of the activation energy required for the pyrolysis reaction is supplied to the preheating reactor, the pyrolysis reactor thus having to supply less energy to enable the plastics to crack.

[0031] In addition, the synthesis gases (also called "syngas"), produced during the thermal and / or catalytic cracking of plastics, are extracted at the first outlet, above the permeable bed, in order to promote the decantation of the chars within the pyrolysis reactor and avoid the transfer of the chars to the syngas recovery line. This extraction of the synthesis gases above the permeable bed is also explained in the event of a partial cracking reaction due to the possibility of different energies supplied between the bottom and the top of the pyrolysis reactor (for example due to heterogeneity of the different types of plastics). Also, this extraction of the gases makes it possible to limit, or even avoid, the clogging of the syngas recovery line. According to one characteristic, the plastics are in the form of granules or flakes whose dimensions are at most 15 to 25 millimeters.

[0032] Advantageously, a step of degassing the pasty mixture is implemented inside the preheating reactor.

[0033] This degassing step consists of degassing, in other words extracting the gases dissolved and / or included in the plastics during fluidization, and in particular the air included in the plastics upstream of the preheating reactor and the air incorporated in the plastics inside the preheating reactor during its fluidization, as well as the volatile organic compounds (VOCs). The interest is twofold, namely to avoid, or at least reduce, the introduction of air inside the pyrolysis reactor, and also to remove contaminants such as volatile organic compounds (VOCs) which would harm the quality of the pyrolysis oil.

[0034] For pyrolysis 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. Pyrolysis oil must therefore contain a low contaminant content, because excessively high levels would make the pyrolysis oil incompatible with industrial processes for remanufacturing plastic from oil. Thus, this degassing step will promote the removal, before pyrolysis, of contaminants such as volatile organic compounds and therefore contribute to an improvement in the quality of the pyrolysis oil to be compatible with the requirements of the "Plastic to Plastic" sector.

[0035] This degassing step can be carried out by an air pump, such as a vacuum pump, in connection with the preheating reactor.

[0036] According to one possibility of the process, before being introduced inside the preheating reactor, the plastic materials are washed dry inside an inlet centrifuge, with air heated to a drying temperature lower than the preheating temperature.

[0037] The advantages of this dry washing by centrifugation and hot air are to eliminate the moisture present in the plastics, and to extract the contaminants accompanying the plastics, such as cellulosic waste, inert waste, metal pieces. This step thus makes it possible to reduce the impact of these contaminants on the quality of pyrolysis oils.

[0038] In other words, this dry washing by centrifugation upstream of the preheating reactor promotes the extraction of sources of pollution for pyrolysis oils, which would make them incompatible with the oil treatment facilities existing today and used for the treatment of natural resources and for the manufacture of plastics within the framework of the “Plastic to Plastic” sector.

[0039] This washing of plastics in a centrifuge upstream of the preheating reactor is therefore an important step in the process with the aim of producing high-quality pyrolytic oils with the aim of remanufacturing plastics that meet the requirements of this “Plastic to Plastic” sector, i.e. within the framework of the circular economy of plastics.

[0040] According to another possibility of the process, before being introduced inside the preheating reactor, the plastic materials are introduced into a cyclone (for example by means of an aeraulic system) having a base provided with an evacuation outlet connected to the preheating reactor.

[0041] Such a cyclone has a dual function: the first function is to extract the quantity of air included in the plastic materials upstream of the preheating reactor, and the second function consists of conveying the plastic materials into the preheating reactor. Furthermore, a bed of granules or flakes of plastic materials is formed at the base of the cyclone generating a plug, on its discharge outlet, and thus preventing the introduction of air into the preheating reactor.

[0042] Alternatively, inside the preheating reactor, the plastics are mixed by means of a screw conveyor.

[0043] Such an endless screw is advantageous for homogenizing the heated plastic materials within the pasty mixture.

[0044] According to one feature, the preheating temperature is between 20 and 290°C inside the preheating reactor.

[0045] It should be noted that this preheating provides, through heat, the energy necessary for the plastics to change state and go from a solid 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 pyrolysis reaction (between 40 and 70% of the total energy) which will take place in the pyrolysis reactor. The preheating step therefore allows a dissociation of the energies involved during the reactions between the plastics and the catalyst.

[0046] The selectivity of the catalyst and the management of the temperatures in the preheating reactor and in the pyrolysis reactor thus make it possible to control the pyrolysis reaction in the pyrolysis reactor in order to obtain an oil quality corresponding to the requirements of the "Plastic to Plastic" sector. In a particular embodiment, inside the preheating reactor, the plastic materials are preheated by means of a heat transfer fluid present or circulating in a double jacket of the preheating reactor.

[0047] Advantageously, the heat transfer fluid of the preheating reactor is heated by a burner supplied at least partially by the non-condensable gases of the synthesis gases recovered from the first outlet of the pyrolysis reactor.

[0048] Thus, these incondensable gases, products of pyrolysis, are used directly in the process, thus offering energy savings.

[0049] In a particular embodiment, between the preheating reactor and the pyrolysis reactor, the pasty mixture passes into a material diffuser heated to a diffusion temperature higher than the preheating temperature.

[0050] If applicable, this diffusion temperature is lower than the activation temperature of the catalyst.

[0051] Such a material diffuser allows for a homogeneous and uniform surface distribution of the pasty mixture on the permeable bed present in the pyrolysis reactor, in order to benefit from the entire energy capacity of the surfaces offered by the permeable bed. 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 heated permeable bed, to improve heat transfer during the pyrolysis reaction.

[0052] This material diffuser therefore has several functions. The first function is to heat the 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 pyrolysis 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 pyrolysis reactor. The third and final function is to make the connection between the preheating reactor and the pyrolysis 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.

[0053] Alternatively, the diffuser and the pyrolysis reactor are connected by a high-temperature sleeve to manage expansion due to temperature differences and promote sealing between the diffuser and the pyrolysis reactor. Alternatively, the permeable bed is subjected to vibration.

[0054] Such vibration promotes the detachment of the tanks, and possibly the catalyst, present on the permeable bed, and therefore their evacuation downwards by gravity descent within the pyrolysis reactor.

[0055] Alternatively, the permeable bed is a fixed bed.

[0056] According to one characteristic, the permeable bed is formed of a lattice composed of meshes delimiting holes, for example made of refractory steel or ceramic.

[0057] In an advantageous embodiment, the permeable bed is heated by means of a heat transfer fluid present or circulating inside the meshes which are tubular.

[0058] Advantageously, the heat transfer fluid of the permeable bed is heated by a burner supplied at least partially by the incondensable gases of the synthesis gases recovered from the first outlet of the pyrolysis reactor; which contributes to a relative or at least partial energy autonomy of the process.

[0059] Alternatively or additionally, the pyrolysis reactor is heated to the pyrolysis temperature by means of a heat transfer fluid present or circulating in a double jacket, this heat transfer fluid being heated by a burner supplied at least partially by the non-condensable gases of the synthesis gases recovered from the first outlet of the pyrolysis reactor.

[0060] According to one variant, the permeable bed is made of heat transfer media, for example made of refractory steel or ceramic.

[0061] Advantageously, the pyrolysis reactor is a narrow and long reaction column (height at least ten times greater than the width or diameter) allowing a long residence time of the plastics, and where appropriate the catalyst, on the permeable bed in order to have an optimal pyrolysis reaction. The choice of a reaction column makes it possible to manage the flow of the material within the pyrolysis reactor to meet a large exchange surface with the permeable bed and ensure a homogeneous distribution, in terms of height and linear distribution, in order to avoid a "vault effect". The use of a reaction column in which the plastics descend by gravity, over a significant height, significantly increases the contact time between the plastics and the permeable bed.

[0062] According to one characteristic, the pyrolysis temperature is stable and between 300 and 900 °C.

[0063] Pyrolysis is thus presented as a continuous pyrolysis at a constant working temperature (called pyrolysis temperature) over a given range allowing the cracking of plastics while obtaining a constant quality of pyrolytic oils; the pyrolysis reactor allowing work at a constant pyrolysis temperature in order to avoid a temperature gradient within the pyrolysis reactor and, if necessary, to manage the working range of the catalyst.

[0064] Indeed, managing the pyrolysis temperature under isothermal conditions (i.e. at a stable pyrolysis temperature) has an impact on the quality of the pyrolysis oils obtained so that they are compatible with the "Plastic to Plastic" sector. Indeed, the catalyst is usable and effective in a well-defined and specific temperature range. Under these conditions, it is therefore advantageous to work with a stable pyrolysis temperature (isothermal condition) in order to control the selectivity of the carbon chain cuts thanks to the catalyst used and thus obtain the desired chemical distribution of the molecules formed in the pyrolysis oils during the pyrolysis reactions.

[0065] These chain breaks will have an impact on the quality of the pyrolysis oils and the catalyst, within the framework of a suitable and constant pyrolysis temperature, allows the polymer chains to be cut in a controlled and oriented manner in order to obtain pyrolysis oils of uniform quality. Thus, this characteristic relating to a stable pyrolysis temperature within the pyrolysis reactor makes it possible to promote the production of pyrolysis oils allowing the production of plastics within the framework of the circular economy of plastics.

[0066] According to one variant, pyrolysis is a “flash” pyrolysis transforming plastic materials into synthesis gas in a time of less than 1 second, or even of the order of 0.01 seconds.

[0067] Advantageously, the solid reaction product, recovered from the second outlet of the pyrolysis reactor, is introduced into a closed regeneration reactor for heating the solid reaction product to a regeneration temperature allowing at least partial regeneration of the catalyst it contains.

[0068] According to one feature, inside the closed regeneration reactor, the solid reaction product is heated by means of a heat transfer fluid present or circulating in a double jacket of the closed regeneration reactor.

[0069] According to another feature, the heat transfer fluid of the closed regeneration reactor is heated by a burner supplied at least partially by the incondensable gases of the synthesis gases recovered from the first outlet of the pyrolysis reactor; which also contributes to a relative or at least partial energy autonomy of the process. According to one possibility, the regeneration temperature is between 300 and 900 °C.

[0070] Alternatively, at the outlet of the closed regeneration reactor, the solid reaction product is introduced into a separator to separate the regenerated catalyst from the chars or a mixture containing the chars and non-regenerated catalyst, the regenerated catalyst being reintroduced into the preheating reactor.

[0071] Thus, the catalyst is at least partially regenerated in the closed regeneration reactor, and recovered at the outlet of the separator to be recycled because it is reinjected into the preheating reactor in order to be mixed with the plastic materials.

[0072] This step is advantageous because it allows the catalyst to be reused after its regeneration by reintroducing it into the preheating reactor, in order to reduce the economic impact of the catalyst. The non-regenerated catalyst and the chars can be treated outside the scope of this process.

[0073] Alternatively, before being introduced into the preheating reactor, the regenerated catalyst is mixed with a new catalyst.

[0074] Alternatively, the new catalyst is mixed with the regenerated catalyst in a predefined proportion and controlled by means of a metering screw.

[0075] In a particular embodiment, the synthesis gases, recovered from the first outlet of the pyrolysis reactor, are introduced into a filtration unit for filtration of suspended particles contained in the synthesis gases, before condensation of the condensable gases from the synthesis gases.

[0076] This advantageous filtration unit thus forms a purification section on the synthesis gas recovery line, in order to separate any impurities from the synthesis gases in order to avoid contamination of the reaction products and also, where appropriate, disruption of the effects of the catalyst.

[0077] Alternatively, the synthesis gases are subjected to cyclonic filtration within at least one cyclone of the filtration unit.

[0078] The cyclone function is advantageous for separating dust and suspended char particles from the synthesis gas, in order to remove dust and volatile chars in order to avoid potential contamination of pyrolysis oils.

[0079] According to another possibility, the synthesis gases are subjected alternately to cyclonic filtration within a first cyclone of the filtration unit and to cyclonic filtration within a second cyclone of the filtration unit, the at least one cyclone of the filtration unit comprising said first cyclone and said second cyclone in parallel.

[0080] Since the plastic pyrolysis process is continuous, it is advantageous to have these two cyclones which are interchangeable and which operate alternately in order to facilitate maintenance and cleaning cycles; in other words, when one of the cyclones is being cleaned, the other is active in purification mode.

[0081] In an advantageous embodiment, after cyclonic filtration, the synthesis gases are subjected to micrometric filtration within at least one micrometric filter of the filtration unit.

[0082] Such micrometric filtration allows for finer filtration of particles and contamination remaining in the synthesis gases, compared to cyclone(s). In other words, this micrometric filtration aims to eliminate microparticles not purified by the previous cycloning step.

[0083] According to one possibility, the synthesis gases are subjected alternately to micrometric filtration within a first micrometric filter of the filtration unit and to micrometric filtration within a second micrometric filter of the filtration unit, the at least one micrometric filter of the filtration unit comprising said first micrometric filter and said second micrometric filter in parallel.

[0084] Since the plastic pyrolysis process is continuous, it is advantageous to have these two micrometric filters which are interchangeable and which operate alternately in order to facilitate maintenance and cleaning cycles; in other words, when one of the micrometric filters is being cleaned, the other is active in filtration mode.

[0085] According to a particular embodiment, the condensable gases of the synthesis gases are successively condensed in at least one primary condenser operating at a primary condensation temperature, then in at least one secondary condenser operating at a secondary condensation temperature, said secondary condensation temperature being lower than the primary condensation temperature.

[0086] After the synthesis gas recovery line, and where appropriate after filtration, these synthesis gases are condensed, preferably during a flash operation which allows the cooling of the synthesis gases at the outlet of the pyrolysis reactor; these synthesis gases comprising incondensable gases (such as carbon monoxide CO, carbon dioxide CO2, methane CH4) and condensable gases of the hydrocarbon type. These synthesis gases may also contain impurities (minor inorganic compounds e.g. metals, alkalis, S, Na, etc.) initially present in the plastics.

[0087] In this situation, the synthesis gases pass through one or more of the primary condensers, which are then conveyed and cooled in this primary condenser in order to provide a necessary thermal shock between the hot synthesis gases and the cold primary condenser. Condensation of the polymer chains present in the synthesis gases then occurs, in the form of pyrolytic oils and a water fraction, which can then be received in a settling tank.

[0088] The proportions of condensing syngas are controlled by controlling the cooling temperature of the primary condenser, called the primary condensation temperature. Preferably, the syngas recovery line, before the primary condenser, is thermally traced to the inlet of the primary condenser(s) in order to avoid premature condensation of the syngas into pyrolysis oils.

[0089] A fraction of the condensable gases that has not been condensed in the primary condenser then passes through the secondary condenser, which operates at a lower temperature, thus causing a greater thermal shock than that used for the primary condenser. This double quenching or condensation effect allows a reduction in energy consumption for cooling the synthesis gases. The secondary condenser is advantageous in causing the condensation of the fraction of non-condensed gases following their passage through the primary condenser. The shorter chains condense in the form of a new fraction of pyrolysis oils, obtained through condensation in the secondary condenser. If necessary, this fraction returns to the settling tank.

[0090] The principle of using two successive condensers at two distinct temperatures makes it possible to condense all (or at least a large part) of the condensable gases into pyrolytic oils, thanks to two different condensation temperatures, and thus makes it possible to maximize the conversion into pyrolytic oils.

[0091] Also, this double condensation in two successive condensers has several advantages.

[0092] The first advantage consists of condensing, in two phases, the condensable fraction of syngas into "light" hydrocarbon molecules so that the pyrolysis oils produced fit into the "Plastic to Plastic" sector and therefore into the circular economy of plastics. Indeed, in order to meet these requirements, the molecules present in the oils must contain short carbon chains, i.e. in the form of liquid at room temperature. The primary condenser allows a certain type of carbon chains to be condensed in a controlled manner. The non-condensed syngas passes through the secondary condenser, whose cooling temperature is colder than that of the primary condenser, allowing condensation of the shortest carbon chains present in the condensable fraction of the syngas in order to recover all the condensable products in the form of pyrolysis oil.

[0093] The second advantage of this double condensation is to increase the conversion of plastic materials into pyrolytic oils with a quality meeting the requirements of the “Plastic to Plastic” sector in order to obtain the highest possible yield.

[0094] The final advantage is to reduce the energy consumption required during syngas condensation by dividing the process with at least two condensers cooled to different temperatures. The temperature of the primary condenser is higher than that of the secondary condenser. The pyrolysis oils obtained under these conditions have a uniform quality that meets the requirements of the "Plastic to Plastic" sector.

[0095] In summary, this double condensation step makes it possible to obtain pyrolytic oils that meet the quality requirements of pyrolytic oils used to produce plastics in the “Plastic to Plastic” sector.

[0096] In an advantageous embodiment, before condensation in the at least one secondary condenser, the condensable gases of the synthesis gases are condensed alternately in a first primary condenser and in a second primary condenser, the at least one primary condenser comprising said first primary condenser and said second primary condenser in parallel.

[0097] Since the plastic pyrolysis process is continuous, it is advantageous to have these two primary condensers which are interchangeable and which operate alternately in order to facilitate maintenance and cleaning cycles; in other words, when one of the primary condensers is being cleaned, the other is active in condensation mode.

[0098] Advantageously, a vacuum pump, arranged downstream of the at least one secondary condenser, provides suction of the synthesis gases into the at least one secondary condenser and evacuation of the incondensable gases on a line for recovering the incondensable gases. The invention also relates to a conversion installation designed for degradation by pyrolysis of plastic materials for conversion into pyrolytic oils, such a conversion installation comprising at least:

[0099] - a continuous plastics supply line;

[0100] - a catalyst supply line;

[0101] - a preheating reactor connected to the continuous plastics supply line and to the catalyst supply line, said preheating reactor being configured to mix the plastics and preheat them to a preheating temperature in order to fluidize them, and to mix the plastics with the catalyst in order to obtain a pasty mixture, the preheating temperature being lower than an activation temperature of the catalyst;

[0102] - a pyrolysis reactor arranged downstream of the preheating reactor and shaped to heat the pasty mixture to a 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 pyrolysis reactor internally integrating a permeable bed, a first outlet located above the permeable bed and a second outlet located below the permeable bed;

[0103] - a synthesis gas recovery line connected to the first outlet of the pyrolysis reactor, the synthesis gases containing condensable gases and non-condensable gases;

[0104] - a solid reaction product recovery line connected to the second outlet of the pyrolysis reactor;

[0105] - a condensation line arranged downstream of the synthesis gas recovery line and designed to condense the condensable gases from the synthesis gases into pyrolytic oils.

[0106] By preheating and mixing the plastics and the catalyst as described above, a homogeneous and pasty mixture of the plastics and the catalyst is obtained.

[0107] According to one feature, the continuous plastics feed line comprises, upstream of the preheating reactor, an inlet centrifuge for dry washing the plastics, with air heated to a drying temperature lower than the preheating temperature. According to another feature, the plastics feed line comprises, upstream of the preheating reactor, a cyclone having a base provided with a discharge outlet connected to the preheating reactor.

[0108] In a particular embodiment, the preheating reactor comprises a worm screw.

[0109] According to one possibility, the preheating reactor comprises a double jacket in which a heated heat transfer fluid is present or circulates.

[0110] According to another possibility, the preheating reactor is associated with a burner for heating the heat transfer fluid of the preheating reactor, said burner being supplied at least partially by the non-condensable gases of the synthesis gases recovered on the synthesis gas recovery line.

[0111] In an advantageous embodiment, the installation comprises, between the preheating reactor and the pyrolysis reactor, a material diffuser for a substantially homogeneous and uniform surface distribution of the pasty mixture inside the pyrolysis reactor, said material diffuser being heated to a diffusion temperature greater than or equal to the preheating temperature and lower than the pyrolysis temperature.

[0112] According to a particular embodiment, the pyrolysis reactor is associated with a vibrator to subject the permeable bed to vibration.

[0113] According to one characteristic, the permeable bed is a fixed bed.

[0114] According to another characteristic, the permeable bed is formed by a lattice composed of meshes delimiting holes, for example made of refractory steel or ceramic.

[0115] According to a particular embodiment, the meshes of the permeable bed are tubular and a heated heat transfer fluid is present or circulates inside said meshes.

[0116] According to one possibility, the pyrolysis reactor is associated with a burner for heating the heat transfer fluid of the permeable bed and / or for heating a heat transfer fluid circulating or present in a double jacket of the pyrolysis reactor, said burner being supplied at least partially by the incondensable gases of the synthesis gases recovered on the synthesis gas recovery line.

[0117] Advantageously, the preheating reactor is connected to an air pump, such as a vacuum pump, for degassing the pasty mixture inside the preheating reactor.

[0118] This air pump thus ensures a degassing function, in order to extract the air included in the plastic materials upstream of the preheating reactor and during fluidification, and also to extract the volatile organic compounds dissolved in the plastic materials, as previously explained.

[0119] In an advantageous embodiment, the installation comprises a closed regeneration reactor connected to the second outlet of the pyrolysis reactor, for heating the solid reaction product to a regeneration temperature allowing at least partial regeneration of the catalyst it contains.

[0120] According to one characteristic, the closed regeneration reactor comprises a double jacket inside which a heated heat transfer fluid is present or circulates.

[0121] According to another characteristic, the closed regeneration reactor is associated with a burner for heating the heat transfer fluid of the closed regeneration reactor, said burner being supplied at least partially by the non-condensable gases of the synthesis gases recovered on the synthesis gas recovery line.

[0122] According to another characteristic, the installation comprises, at the outlet of the closed regeneration reactor, a separator for carrying out a separation between regenerated catalyst and the chars or a mixture containing the chars and non-regenerated catalyst, the separator comprising a first outlet for the regenerated catalyst and a second outlet for the chars or the mixture containing the chars and the non-regenerated catalyst.

[0123] According to a particular embodiment, the installation comprises a return line connecting the first outlet of the separator to the catalyst supply line in order to reintroduce the regenerated catalyst inside the preheating reactor.

[0124] In a particular embodiment, the catalyst supply line is connected to a storage volume for new catalyst in order to mix the regenerated catalyst and the new catalyst before introduction into the preheating reactor.

[0125] According to one feature, the catalyst supply line comprises a metering screw for mixing the new catalyst with the regenerated catalyst in a predefined and controlled proportion.

[0126] According to a particular embodiment, the synthesis gas recovery line comprises a filtration unit for filtering suspended particles contained in the synthesis gases, before condensation of the condensable gases of the synthesis gases in the condensation line.

[0127] According to one feature, the filtration unit comprises at least one cyclone for subjecting the synthesis gases to cyclonic filtration. According to another feature, the at least one cyclone of the filtration unit comprises a first cyclone and a second cyclone in parallel for subjecting the synthesis gases alternately to cyclonic filtration within the first cyclone and to cyclonic filtration within the second cyclone.

[0128] According to another characteristic, the filtration unit comprises, downstream of the at least one cyclone, at least one micrometric filter for subjecting the synthesis gases to micrometric filtration.

[0129] According to another characteristic, the at least one micrometric filter comprises a first micrometric filter and a second micrometric filter in parallel to subject the synthesis gases alternately to micrometric filtration within the first micrometric filter and to micrometric filtration within the second micrometric filter.

[0130] According to one possibility, the condensation line successively comprises at least one primary condenser operating at a primary condensation temperature, and at least one secondary condenser operating at a secondary condensation temperature, said secondary condensation temperature being lower than the primary condensation temperature.

[0131] Alternatively, the at least one primary condenser comprises a first primary condenser and a second primary condenser in parallel for condensing the condensable gases of the synthesis gases alternately in the first primary condenser and in the second primary condenser.

[0132] In an advantageous embodiment, the installation comprises a line for recovering incondensable gases on which a vacuum pump is arranged downstream of the at least one secondary condenser, for suction of the synthesis gases into the at least one secondary condenser and evacuation of the incondensable gases.

[0133] [Brief description of the figures]

[0134] Other characteristics and advantages of the present invention will appear on reading the detailed description below, of two non-limiting examples of implementation, made with reference to the appended figures in which:

[0135] [Fig 1] is a schematic view of part of a plastic pyrolysis installation according to the invention, comprising in particular the plastics supply line, the catalyst supply line, the preheating reactor and the pyrolysis reactor; [Fig 2] is a schematic view of another part of the installation of Figure 1, and in particular of the synthesis gas recovery line and the condensation line;

[0136] [Fig 3] is a schematic view of a variant of the other part of Figure 2.

[0137] [Detailed description of one or more embodiments of the invention]

[0138] With reference to the Figures, a conversion plant 1 is provided for pyrolytic degradation of plastic materials for conversion of these plastic materials into pyrolytic oils.

[0139] The conversion plant 1 comprises a continuous feed line 2 for the plastic materials, which conveys the bulk plastic materials and which successively comprises an inlet centrifuge 20 and a cyclone 21.

[0140] The inlet centrifuge 20 continuously receives plastic materials as an inlet for dry washing the raw plastic materials, which are in the form of granules or flakes with dimensions of a maximum of 15 to 25 millimeters. The inlet centrifuge 20 is designed to dry wash the plastic materials, for the purpose of decontaminating them, with air heated to a given drying temperature, for example of the order of 40 to 80 °C. This inlet centrifuge 20 has an outlet 24 for the reflux generated by the washing of the plastic materials.

[0141] The cyclone 21 is connected to an outlet of the inlet centrifuge 20 to receive the washed plastic materials (or those cleaned of contamination) as an inlet, and this cyclone 21 has a base (in the lower part) provided with an evacuation outlet 22, as well as a suction mouth in the upper part which is connected to a suction path 23 to suck air into the cyclone 21. Thus an extraction of air takes place in this cyclone 21, and a plug of plastic materials is formed at the base of the cyclone 21, thus creating an airtight seal on the evacuation outlet 22. This cyclone 21 makes it possible to reduce the quantity of air included in the plastic materials.

[0142] The conversion plant 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. The 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 combined.

[0143] The discharge outlet 22 of the cyclone 21 is connected to the first inlet 30 of the preheating reactor 3. According to an advantageous possibility, the discharge outlet 22 of the cyclone 21 is arranged above the first inlet 30 of the preheating reactor 3 for feeding by gravity fall of the plastic materials.

[0144] 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.

[0145] The preheating temperature is higher than a plastics fluidization temperature in order to effect a phase transition between a solid state and a viscous state. The preheating temperature is lower than the catalyst activation temperature, and also the pyrolysis temperature which corresponds to the plastics cracking temperature. The preheating temperature is for example between 20 and 290 °C inside the preheating reactor 3.

[0146] Advantageously, the preheating reactor 3 comprises an endless screw 32, and the introduction of the plastic materials 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.

[0147] This preheating reactor 3 is connected to an air pump 33, such as a vacuum pump, which provides a degassing function, in order to extract the 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. The air pump 33 may be followed by one or more filters 34, such as for example a volatile organic compound filter, for filtration and treatment of the dissolved gases and included in the plastics before discharge into the atmosphere. This preheating reactor 3 comprises a double jacket (or sheath) in which a heat transfer fluid heated by a burner 91 is present or circulates; this burner 91 is thus adjusted to heat the heat transfer fluid of the preheating reactor 3 to the preheating temperature.

[0148] The conversion installation 1 comprises a material diffuser 35, 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 35. This material diffuser 35 has the function of ensuring a substantially homogeneous and uniform surface distribution of the pasty mixture at its outlet 36. The material diffuser 35 can be heated to a diffusion temperature greater than or equal to the preheating temperature and less than the pyrolysis temperature, in order to maintain the pasty mixture in a viscous state. This diffusion temperature can be between 200 and 300 °C.

[0149] The conversion installation 1 comprises a pyrolysis reactor 5 connected to the outlet 36 of the material diffuser 35; this pyrolysis reactor 5 is therefore arranged downstream of the preheating reactor 3 and is configured to heat the pasty mixture to a pyrolysis 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 pyrolysis reactor 5, an anaerobic and continuous pyrolysis or cracking reaction of the plastics occurs, promoted by the catalyst.

[0150] The pyrolysis reactor 5 internally incorporates a permeable bed 50 which is a fixed bed. This permeable bed 50 may for example be formed of a lattice composed of meshes delimiting holes, or alternatively be formed of heat transfer media. The meshes of the lattice or the heat transfer media are for example made of refractory steel or ceramic.

[0151] The pyrolysis or cracking reaction therefore takes place between the plastics and the catalyst during contact with the permeable bed 50 heated within the pyrolysis reactor 5, in an anaerobic or inert atmosphere and with a fixed and stable pyrolysis temperature, for example between 300 and 900°C. This reaction leads to cracking and therefore depolymerization of the plastics.

[0152] The pyrolysis reactor 5 has a first outlet 51 located above the permeable bed 50 for the evacuation and recovery of the synthesis gases, and a second outlet 52 located below the permeable bed 50 for evacuation and recovery of the solid reaction product. The second outlet 52 is for example provided at the base of the pyrolysis reactor 5, in the lower part of the pyrolysis reactor 5.

[0153] The synthesis gases therefore exit at the first outlet 51 which is above the permeable bed 50 in order to promote the settling of the chars within the pyrolysis reactor 5, with the aim of avoiding the transfer of the chars to the first outlet 51 and thus not contaminating the synthesis gases.

[0154] The outlet 36 of the material diffuser 35 is connected to the top of the pyrolysis reactor 5 (in other words in the upper part of the pyrolysis reactor 5) and this material diffuser 35 provides a substantially homogeneous and uniform surface distribution of the pasty mixture inside the pyrolysis reactor 5 and on its permeable bed 50. Advantageously, the connection between the material diffuser 35 and the pyrolysis 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 35 and the pyrolysis reactor 5, and thus preserve the seal.

[0155] The pyrolysis reactor 5 is associated with a burner 92 which is set to heat a heat transfer fluid to the pyrolysis temperature, in order to heat the pyrolysis reactor 5 and its permeable bed 50 to the pyrolysis temperature.

[0156] According to a first possibility, the heat transfer fluid is present or circulates inside a double jacket of the pyrolysis reactor 5.

[0157] According to a second possibility (in addition to or as a variant of the first possibility mentioned above), the heat transfer fluid is present or circulates inside the permeable bed 50, and for example inside the meshes of the permeable bed 50 which are tubular.

[0158] Optionally, this pyrolysis reactor 5 integrates or comprises a vibrator for subjecting the permeable bed 50 to vibration, in order to promote the detachment of the tanks and the catalyst from the permeable bed 50, and thus their gravitational descent into the pyrolysis reactor 5.

[0159] The conversion installation 1 comprises a solid reaction product recovery line 6 connected to the second outlet 52 of the pyrolysis 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 pyrolysis 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.

[0160] This solid reaction product recovery line 6 comprises a regeneration reactor 60 connected to the second outlet 52 of the pyrolysis 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 function of regenerating the used catalyst contained in the solid reaction product at the outlet of the pyrolysis reactor 5, with the aim of being able to reuse it.

[0161] This regeneration reactor 60 is a closed reactor, also called a “batch” reactor. The regeneration temperature is for example between 300 and 900°C to regenerate the catalyst and separate the regenerated catalyst and the chars.

[0162] Since this regeneration reactor 60 is a closed reactor, and the solid reaction product continuously leaves the pyrolysis reactor 5, it is advantageous to use a buffer device between the second outlet 52 of the pyrolysis reactor 5 and the regeneration reactor 60, such as for example a bimetallic guillotine valve to isolate the continuous work of the pyrolysis reactor 5 and the work cycles of the regeneration reactor 60.

[0163] This regeneration reactor 60 comprises a double jacket in which a heat transfer fluid heated by a burner 93 is present or circulates; this burner 93 is thus adjusted to heat the heat transfer fluid of the regeneration reactor 60 to the regeneration temperature.

[0164] This solid reaction product recovery line 6 comprises, at the outlet of the regeneration reactor 60, a separator 61 for carrying out a separation between the regenerated catalyst and the chars or a mixture containing the chars and non-regenerated catalyst. This separator 61 comprises a first outlet 62 for recovering the regenerated catalyst, and a second outlet 63 for recovering the chars or the mixture containing the chars and the non-regenerated catalyst.

[0165] It is advantageous to use another buffer device, this time between the regeneration reactor 60 and the separator 61, such as for example a bimetallic guillotine valve, to isolate the working cycles of the regeneration reactor 60 and the continuous work of the separator 61.

[0166] The conversion installation 1 comprises a return line 41 connecting the first outlet 62 of the separator 61 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.

[0167] 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 61, 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. The catalyst supply line 4 thus comprises a metering screw 42 for metering and mixing the new catalyst with the regenerated catalyst in a predefined and controlled proportion.

[0168] The solid reaction product recovery line 6 comprises a collector 64, connected to the second outlet 63 of the separator 61 to collect the chars and the non-regenerated catalyst, this collector 64 being followed by a conveyor 65, such as for example an extraction screw 65, to convey the chars and the non-regenerated catalyst to a storage space 66. The chars thus collected may possibly be subject to treatment for recovery.

[0169] The conversion plant 1 comprises a synthesis gas recovery line 7 connected to the first outlet 51 of the pyrolysis 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 pyrolysis reactor 5, in order to avoid premature condensation of the condensable gases into pyrolysis oils.

[0170] The synthesis gas recovery line includes a filtration unit 70 for filtration of suspended particles contained in the synthesis gas, such as, for example, char particles or other types of dust.

[0171] In the example of Figure 2, this filtration unit 70 comprises a cyclone 71 for subjecting the synthesis gases to cyclonic filtration, and a micrometric filter, arranged downstream of the cyclone 71, for subjecting the synthesis gases to micrometric filtration; micrometric filtration being a finer filtration of the particles and contaminations remaining in the synthesis gases, compared to cyclonic filtration.

[0172] Furthermore, the cyclone 71 has at its base a particle discharge outlet, which is connected to a sealing device 74 to prevent air from entering the cyclone 71, and thus avoid mixing the synthesis gases with air.

[0173] This sealing device 74 may be in the form, for example, of a drawer incorporating two successive valves for airlock type operation. Such a two-valve drawer comprises a high valve upstream of the cyclone discharge outlet 71 and a low valve connected to a particle collection point. The two-valve drawer operates cyclically as follows:

[0174] - in a first phase, the upper valve is open and the lower valve is closed, to allow the particles to be evacuated from the cyclone to the drawer; - in a second phase, the upper valve is closed and the lower valve is open, to allow the drawer to be purged.

[0175] The opening and closing of the drawer valves are managed by the level of particles present inside the cyclone 71; the purging of the drawer is carried out cyclically.

[0176] In the example of Figure 3, this filtration unit 70 comprises a first cyclone 71a and a second cyclone 71b in parallel to subject the synthesis gases alternately to cyclonic filtration within the first cyclone 71a and to cyclonic filtration within the second cyclone 71b. A three-way valve 73 is arranged between the first outlet 51 of the pyrolysis reactor 5 and the two cyclones 71a, 71b, in order to direct the synthesis gases alternately towards the first cyclone 71a and towards the second cyclone 71b.

[0177] Furthermore, each of the two cyclones 71a, 71b has at its base a particle discharge outlet, which is connected to a sealing device 74a, 74b to prevent air from entering, such as for example a two-valve slide valve as described above.

[0178] In the example of Figure 3, the filtration unit 70 further comprises a first micrometric filter 72a, downstream of the first cyclone 71a, and a second micrometric filter 72b, downstream of the second cyclone 71b, for subjecting the synthesis gases alternately to micrometric filtration within the first micrometric filter 72a and to micrometric filtration within the second micrometric filter 72b. Another three-way valve 75 is provided downstream of the first micrometric filter 72a and the second micrometric filter 72b.

[0179] The example of Figure 3 is advantageous in terms of maintenance. Indeed, since the process is continuous, the two cyclones 71a, 71b are interchangeable and operate alternately in order to facilitate maintenance and cleaning cycles; when one of the two cyclones 71a, 71b is being cleaned, the other is active in purification mode.

[0180] Likewise, the two micrometric filters 72a, 72b are interchangeable and operate alternately in order to also facilitate maintenance and cleaning cycles: when one of the two micrometric filters 72a, 72b is being cleaned, the other is active and in filtration mode.

[0181] The conversion installation 1 comprises a condensation line 8 arranged downstream of the synthesis gas recovery line 7 and shaped to condense the condensable gases of the synthesis gases into pyrolytic oils. The condensation line 8 successively comprises at least one primary condenser 81, 81a, 81b operating at a primary condensation temperature, and at least one secondary condenser 82 operating at a secondary condensation temperature, where this secondary condensation temperature is lower than the primary condensation temperature.

[0182] A thermal shock is necessary between the hot synthesis gases and the primary condenser(s) 81, 81a, 81b 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 pyrolytic oil and a water fraction. The proportions of condensing gases are controlled by controlling the cooling temperature of the primary condenser(s) 81, 81a, 81b. The condensation line 8 is thermally traced to the inlet of the primary condenser(s) 81, 81a, 81b, in order to avoid premature condensation of the synthesis gases into pyrolytic oil before the primary condenser(s) 81, 81a, 81b.

[0183] In the example of Figure 2, this condensation line 8 comprises a single primary condenser 81.

[0184] In the example of Figure 3, this condensation line 8 comprises a first primary condenser 81a and a second primary condenser 81b in parallel to condense the condensable gases of the synthesis gases alternately in the first primary condenser 81a and in the second primary condenser 81b. A three-way inlet valve 83 is arranged upstream of the two primary condensers 81a, 81b, in order to direct the synthesis gases alternately towards the first primary condenser 81a and towards the second primary condenser 81b. A three-way outlet valve 84 is arranged downstream of the two primary condensers 81a, 81b.

[0185] The process being continuous, the two primary condensers 81a, 81b are interchangeable and operate alternately in order to facilitate maintenance and cleaning cycles: when one of the two primary condensers 81a, 81b is being cleaned, the other is active and in condensation mode.

[0186] The condensation line 8 comprises, between the primary condenser 81 or the primary condensers 81a, 81b and the secondary condenser 82, a settling tank 85 containing the pyrolytic oils and possibly the condensed water, resulting from the condensation in the primary condenser(s) 81, 81a, 81b.

[0187] The secondary condenser 82 is traversed by a colder temperature than that of the primary condenser(s) 81, 81a, 81b, and therefore this secondary condenser 82 causes a greater thermal shock than that used for the primary condenser(s) 81, 81a, 81b. Thus this secondary condenser 82 allows condensation of the fraction of non-condensed gases following their passage through the primary condenser(s) 81, 81a, 81b. The shorter chains are therefore condensed in the secondary condenser 82 in the form of a new fraction of pyrolytic oil, obtained thanks to the second condensation, and this new fraction of pyrolytic oil also joins the settling tank 85.

[0188] The condensation line 8 comprises a vacuum pump 80, arranged downstream of the secondary condenser 82, in order to create a vacuum allowing the suction into the secondary condenser 82 of the fraction of synthesis gases not condensed in the primary condenser(s) 81, 81a, 81b. Thus, this fraction undergoes a new condensation within the secondary condenser 82, as described previously. The vacuum pump 80 therefore makes it possible to provide a vacuum in the circuit and to promote the arrival of the synthesis gases into the secondary condenser 82.

[0189] The condensation line 8 comprises, following the settling tank 85, a separator 86 for separating the pyrolytic oil fractions and potentially the condensed water fraction, in order to direct the pyrolytic oils into a homogenization tank 87 and the condensed water fraction to a water recovery tank 88. This separator 86 potentially makes it possible to isolate the water fraction contained in the plastic materials during the introduction of the plastic materials onto the continuous feed line 2.

[0190] The homogenization tank 87 thus collects the different fractions of pyrolytic oils, arriving from the decantation tank 85, to carry out homogenization of the pyrolytic oils before their storage.

[0191] Advantageously, the vacuum pump 80 is arranged on a non-condensable gas recovery line 9 on which a vacuum pump is arranged downstream of the at least one secondary condenser, for evacuation of the non-condensable gases.

[0192] As seen in Figure 1, this incondensable gas recovery line 9 is connected to the burners 91, 92, 93 to convey the incondensable gases into these burners 91, 92, 93 and thus feed these burners 91, 92, 93 at least partially with the incondensable gases of the synthesis gases. In this way, the incondensable gases resulting from the pyrolysis reaction serve as an energy source to thermally power the preheating in the preheating reactor 3, the pyrolysis in the pyrolysis reactor 5, and the regeneration in the regeneration reactor 60. It is conceivable to supplement this gas supply to the burners 91, 92, 93 with another gas, such as for example natural gas or propane.It is possible to provide a boiler 90 equipped with a burner 94 also supplied by the incondensable gases coming from this incondensable gas recovery line 9; such a boiler 90 thus allows the combustion of the incondensable gases and the production of energy for applications external to the conversion installation 1.

[0193] In addition, the burners 91, 92, 93, 94 can be connected to a flue gas recovery line 95 which are obtained during the combustion of the incondensable gases by the burners 91, 92, 93, 94. This flue gas recovery line 95 is connected to a flue gas treatment unit 96 to subject these flue gases to treatment enabling them to be purified of the various sources of contaminants before being discharged into the atmosphere through a chimney 97. This flue gas treatment thus makes it possible to comply with environmental regulations for the discharge of flue gases into the atmosphere while being part of a circular economy.

[0194] It should be noted that all stages 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 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 conversion plant 1.

Claims

CLAIMS 1. Conversion process implementing degradation by pyrolysis of plastic materials for conversion into pyrolytic oils, said conversion process comprising at least the following phases: - the plastics are continuously fed into a preheating reactor (3) in order to be mixed and preheated to a preheating temperature to fluidize them, and a catalyst is continuously fed into the preheating reactor to be mixed with the plastics and obtain a pasty mixture, the preheating temperature being lower than an activation temperature of the catalyst; - the pasty mixture is continuously transferred into a pyrolysis reactor (5) to be heated to a 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 pyrolysis reactor (5) and through a permeable bed (50) which is heated to the pyrolysis temperature; - the synthesis gases, containing condensable gases and non-condensable gases, are recovered at a first outlet (51) of the pyrolysis reactor (5) located above the permeable bed (50), and the solid reaction product is recovered at a second outlet (52) of the pyrolysis reactor (5) located below the permeable bed (50); - the condensable gases from the synthesis gases are condensed into pyrolytic oils which are recovered.

2. Conversion method according to claim 1, in which a step of degassing the pasty mixture inside the preheating reactor (3) is carried out.

3. Conversion method according to claim 1 or 2, in which, before being introduced inside the preheating reactor (3), the plastic materials are washed dry inside an inlet centrifuge (20), with air heated to a drying temperature lower than the preheating temperature.

4. Conversion method according to any one of the preceding claims, wherein, inside the preheating reactor (3), the plastic materials are mixed by means of a worm screw (32).

5. Conversion process according to any one of the preceding claims, wherein the preheating temperature is between 20 and 290°C inside the preheating reactor.

6. Conversion method according to any one of the preceding claims, in which, between the preheating reactor (3) and the pyrolysis reactor (5), the pasty mixture passes into a material diffuser (35) for a substantially homogeneous and uniform surface distribution of the pasty mixture inside the pyrolysis reactor (5), said material diffuser (35) being heated to a diffusion temperature greater than or equal to the preheating temperature and lower than the pyrolysis temperature.

7. Conversion method according to any one of the preceding claims, in which the permeable bed (50) is subjected to vibration.

8. Conversion method according to any one of the preceding claims, in which the permeable bed (50) is a fixed bed.

9. Conversion method according to any one of the preceding claims, in which the permeable bed (50) is formed from a lattice composed of meshes delimiting holes, for example made of refractory steel or ceramic.

10. Conversion process according to any one of the preceding claims, in which the pyrolysis temperature is stable and between 300 and 900°C.

11. Conversion method according to any one of the preceding claims, in which the solid reaction product, recovered from the second outlet (52) of the pyrolysis reactor (5), is introduced into a closed regeneration reactor (60) for heating the solid reaction product to a regeneration temperature allowing at least partial regeneration of the catalyst which it contains.

12. Conversion method according to claim 11, in which, at the outlet of the closed regeneration reactor (60), the solid reaction product is introduced into a separator (61) to carry out a separation between regenerated catalyst and the chars or a mixture containing the chars and non-regenerated catalyst, the regenerated catalyst being reintroduced into the preheating reactor (3).

13. Conversion process according to claim 12, in which, before its introduction into the preheating reactor (3), the regenerated catalyst is mixed with a new catalyst.

14. Conversion method according to any one of the preceding claims, in which the synthesis gases, recovered from the first outlet (51) of the pyrolysis reactor (5), are introduced into a filtration unit (70) for filtration of suspended particles contained in the synthesis gases, before condensation of the condensable gases of the synthesis gases.

15. Conversion method according to claim 14, in which the synthesis gases are subjected to cyclonic filtration within at least one cyclone (71; 71a, 71b) of the filtration unit (70).

16. Conversion method according to claim 15, wherein the synthesis gases are subjected alternately to cyclonic filtration within a first cyclone (71a) of the filtration unit (70) and to cyclonic filtration within a second cyclone (71b) of the filtration unit (70), the at least one cyclone of the filtration unit (70) comprising said first cyclone (71a) and said second cyclone (71b) in parallel.

17. Conversion method according to claim 15 or 16, in which, after cyclonic filtration, the synthesis gases are subjected to micrometric filtration within at least one micrometric filter (72; 72a, 72b) of the filtration unit (70).

18. Conversion method according to claim 17, wherein the synthesis gases are subjected alternately to micrometric filtration within a first micrometric filter (72a) of the filtration unit (70) and to micrometric filtration within a second micrometric filter (72b) of the filtration unit (70), the at least one micrometric filter of the filtration unit (70) comprising said first micrometric filter (72a) and said second micrometric filter (72b) in parallel.

19. Conversion method according to any one of the preceding claims, in which the condensable gases of the synthesis gases are successively condensed in at least one primary condenser (81; 81a, 81b) operating at a primary condensation temperature, then in at least one condenser secondary (82) operating at a secondary condensation temperature, said secondary condensation temperature being lower than the primary condensation temperature.

20. Conversion method according to claim 19, wherein, before condensation in the at least one secondary condenser (82), the condensable gases of the synthesis gases are condensed alternately in a first primary condenser (81a) and in a second primary condenser (81b), the at least one primary condenser comprising said first primary condenser (81a) and said second primary condenser (81b) in parallel.

21. Plastic pyrolysis method according to claim 19 or 20, in which a vacuum pump (80), arranged downstream of the at least one secondary condenser (82), provides suction of the synthesis gases into the at least one secondary condenser (82) and evacuation of the incondensable gases on a line for recovering the incondensable gases (9).

22. Conversion plant (1) for pyrolysis degradation of plastic materials for conversion into pyrolytic oils, said conversion plant (1) comprising at least: - a continuous plastics supply line (2); - a catalyst supply line (4); - a preheating reactor (3) connected to the continuous plastics supply line (2) and to the catalyst supply line (4), said preheating reactor (3) being configured to mix the plastics and preheat them to a preheating temperature in order to fluidize them, and to mix the plastics with the catalyst in order to obtain a pasty mixture, the preheating temperature being lower than an activation temperature of the catalyst; - a pyrolysis reactor (5) arranged downstream of the preheating reactor (3) and shaped to heat the pasty mixture to a pyrolysis temperature, 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 and a solid reaction product containing at least chars, the pyrolysis reactor internally integrating a permeable bed (50), a first outlet (51) located above the permeable bed (50) and a second outlet (52) located below the permeable bed (50); - a synthesis gas recovery line (7) connected to the first outlet (51) of the pyrolysis reactor (5), the synthesis gases containing condensable gases and non-condensable gases; - a solid reaction product recovery line (6) connected to the second outlet (52) of the pyrolysis reactor (5); - a condensation line (8) arranged downstream of the synthesis gas recovery line (7) and shaped to condense the condensable gases of the synthesis gases into pyrolytic oils.

23. Conversion installation (1) according to claim 22, comprising an air pump (33) connected to the preheating reactor (3) for degassing the pasty mixture inside the preheating reactor (3).

24. Conversion plant (1) according to claim 22 or 23, in which the continuous plastics feed line (2) comprises, upstream of the preheating reactor (3), an inlet centrifuge (20) for dry washing the plastics, with air heated to a drying temperature lower than the preheating temperature.

25. Conversion installation (1) according to any one of claims 22 to 24, comprising, between the preheating reactor (3) and the pyrolysis reactor (5), a material diffuser (35) for a substantially homogeneous and uniform surface distribution of the pasty mixture inside the pyrolysis reactor (5), said material diffuser (35) being heated to a diffusion temperature greater than or equal to the preheating temperature and lower than the pyrolysis temperature.

26. Conversion installation (1) according to any one of claims 22 to 25, comprising a closed regeneration reactor (60) connected to the second outlet (52) of the pyrolysis reactor (5), for heating the solid reaction product to a regeneration temperature allowing at least partial regeneration of the catalyst which it contains.

27. Conversion installation (1) according to claim 26, comprising, at the outlet of the closed regeneration reactor (60), a separator (61) for carrying out a separation between regenerated catalyst and the chars or a mixture containing the chars and non-regenerated catalyst, the separator (61) comprising a first outlet for the regenerated catalyst and a second outlet for the chars or the mixture containing the chars and the non-regenerated catalyst.

28. Conversion installation (1) according to any one of claims 22 to 1, in which the condensation line (8) successively comprises at least one primary condenser (81; 81a, 81b) operating at a primary condensation temperature, and at least one secondary condenser (82) operating at a secondary condensation temperature, said secondary condensation temperature being lower than the primary condensation temperature.

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