Method for processing composite material waste, device for implementing the method and recycled fibre obtained thereby

Abstract

The invention relates to a method for processing a composite material comprising reinforcing fibres and an organic compound in which a post-processing step of oxidising the composite material comprises: a step of heating the reactor (100) to a first temperature of between 300°C and 600°C; a step of injecting oxygen into the reactor, which step is configured to produce an oxygen content of between 2% and 15% of a reaction volume of the reactor; a step of injecting steam into the reactor; this steam being superheated to a temperature of between 300°C and 600°C; and a step of oxidising the organic compound into CO and / or into CO2. The invention also relates to a processing device configured to implement the method and to recycled fibre obtained thereby.

Description

[0001] Process for treating composite material waste, device for implementing the process and recycled fiber obtained

[0002] The present invention relates to a method for treating composite material waste.

[0003] It relates in particular to a method for treating a composite material with fiber reinforcement, such as, for example, mainly carbon, glass, basalt or other fibers (manufacturing waste, end-of-life elements from the aeronautics, automotive, nautical industries, etc.), i.e. a material comprising fibers coated at least in part with an organic compound.

[0004] It also relates to a processing device configured to implement the method.

[0005] Finally, it concerns a recycled fiber obtained by the process.

[0006] A composite material as considered herein typically comprises fibers and a matrix (i.e., an organic compound, for example, an organic resin of a polymer material) in which the fibers are embedded.

[0007] To recycle such a material, one possibility is to separate the matrix and the fibers, i.e. rid the fibers of the matrix that may surround them, and thus at least recover the material constituting the fibers (carbon, glass, basalt or other for example), with a minimum of impurities possible.

[0008] For this, a composite material can undergo a thermolysis or vapo-thermolysis process.

[0009] A vapo-thermolysis process, for example, allows the organic matrix of composite materials to be decomposed by thermal cracking in the presence of superheated water vapor and in the absence of oxygen. This process allows for a more complete decomposition of the polymer constituting the matrix compared to a conventional pyrolysis process, thanks to a more oxidizing environment while reducing fiber damage thanks to less severe operating conditions (for example, the temperature can be lower, or the residence time shorter). A thermolysis reactor then operates, for example, in a very slightly negative pressure atmosphere. The fibers obtained after vapo-thermolysis (also called "rCF" for "recovered Carbon Fibers" in the case of carbon fibers) can, for example, then be used to produce products, then designated as "semi-finished products" (chopped fibers, short fibers, non-woven fabrics, staple fiber yarn, threads, etc.)), because these products can then subsequently be used as raw material to produce a composite material based on recycled material. These semi-finished products are thus, for example, intended for the manufacture, by third-party manufacturers, of new composite materials, for example for the automotive, nautical construction, or even aeronautical or energy sectors.

[0010] However, the resin can be difficult to remove by a simple thermolysis or vapo-thermolysis step.

[0011] Therefore, unwanted organic compounds may remain present on a fiber.

[0012] The present invention thus aims to propose a method for treating composite materials improving the elimination of organic compounds on reinforcing fibers.

[0013] To this end, according to a first aspect of the invention, a method is proposed for treating a composite material comprising reinforcing fibers and an organic compound coating at least in part one of the fibers, the method comprising a step of oxidizing post-treatment of the composite material, in a reactor, the step of oxidizing post-treatment comprising:

[0014] - a step of heating the reactor to a first temperature between 300°C and 600°C;

[0015] - a step of injecting oxygen (O2) into the reactor configured to produce an oxygen content of between 2% and 15% of a reaction volume of the reactor,

[0016] - a step of injecting steam into the reactor; this steam being superheated to a temperature between 300°C and 600°C, for example to the first temperature, and

[0017] - a step of oxidation of the organic compound into carbon monoxide (CO) and / or carbon dioxide (CO2). Oxidative post-treatment therefore refers here to a step of oxidation of the material which is carried out after a thermolysis (or vapo-thermolysis) type treatment, in a reactor.

[0018] The process then includes an additional treatment step: the oxidative post-treatment step, which can therefore be implemented in addition to the thermolysis or vapo-thermolysis step in order to eliminate the organic compound. An oxidative post-treatment step here consists of injecting a controlled quantity of oxygen into a reactor which is maintained at a defined and controlled temperature.

[0019] In the context of the treatment of composite materials considered here, this oxidative post-treatment step is configured to oxidize organic compounds still present on a fiber to transform them into carbon monoxide (CO) and / or carbon dioxide (CO2).

[0020] Such a step thus makes it possible to remove a part of the organic compound which is not degraded, or not degradable, or not entirely degradable, by thermolysis or vapo-thermolysis, whatever the operating conditions, as well as, where appropriate, other organic compounds (such as tars, chars or other residues) which may have been obtained by transformation of the organic compound of the composite material during the prior thermolysis or vapo-thermolysis step.

[0021] A steam injection step into the reactor during the oxidative post-treatment step has the particular advantage of enabling the oxidative post-treatment reaction to be stabilized, for example by stabilizing the reactor temperature.

[0022] It also helps, for example, to limit the risk of fire starting; without steam, combustion problems can occur.

[0023] In an exemplary implementation, the step of injecting oxygen into the reactor may comprise an injection of pure oxygen, or of any gas containing oxygen, such as for example ambient air, or a nitrogen-dioxygen complex.

[0024] In an example of implementation, the reactor in which the oxidative post-treatment step is implemented is the same reactor as that in which the thermolysis or vapo-thermolysis is carried out. However, it may be another reactor, which would then be downstream of that of the thermolysis or vapo-thermolysis.

[0025] In one exemplary implementation, the oxygen is injected into the reactor at an ambient temperature, for example, between 15°C and 50°C. In another exemplary implementation, the oxygen is injected into the reactor after being heated, for example to a temperature between 50°C and 600°C, for example between 300°C and 600°C, for example to the first temperature.

[0026] In an exemplary implementation, oxygen is injected into the reactor for a period of between 10 minutes and 6 hours.

[0027] For example, oxygen is injected into the reactor at a flow rate configured to reach and then maintain a dioxygen (O2) content of 2% to 15% in the reactor.

[0028] The flow rate can therefore be very variable, for example between 10 and 1000 m 3 / h.

[0029] In an example implementation, the oxidative post-treatment step includes:

[0030] - A temperature reduction step in the reactor, from the first temperature to a second temperature, the second temperature being between 300°C and 500°C (depending on the organic compound);

[0031] - A step of maintaining the second temperature in the reactor for a period of between 10 min and 6 hours; and

[0032] - A step of introducing oxygen (O2) into the reactor.

[0033] In an exemplary implementation, the oxidative post-treatment step may further comprise a step of reducing steam injection into the reactor.

[0034] When steam injection is reduced, the steam injection rate is lower, and depends for example on a reactor size (for example its internal volume, and / or a quantity of material to be treated present in the reactor).

[0035] In an example implementation, steam injection can be stopped (i.e. a flow rate of 0 m 3 / hour). In practice, the temperature in the reactor can often fluctuate because an oxidative post-treatment reaction can be exothermic.

[0036] However, the oxidative post-treatment may be carried out, at least in part, after the temperature reduction step, or during the temperature reduction step.

[0037] In an exemplary implementation, the oxidative post-treatment step may further comprise at least one step of simultaneous or alternating dosing of the steam and dioxygen (O2) flow rates to maintain the temperature and the dioxygen (O2) content of the reaction medium, respectively between 300°C and 600°C and 2% to 15%.

[0038] In an exemplary implementation, the step of reducing the temperature from the first temperature to the second temperature includes a step of reducing the temperature of the superheated steam injected into the reactor.

[0039] In an exemplary implementation, the method comprises a step of measuring a quantity of oxygen at the outlet of the reactor.

[0040] In an exemplary implementation, the step of introducing oxygen into the reactor comprises a step of regulating the injection flow rate as a function of an oxygen content at the outlet of the reactor.

[0041] For example, if an oxygen content is stable, the process involves:

[0042] - An oxygen injection stop step; and / or

[0043] - A steam heating stop step; and / or

[0044] - A reactor cooling stage including a saturated steam injection stage.

[0045] "Stable" means a variation in oxygen content of less than 20%, or even less than 10%, for a period of at least 10 minutes, for example 10 to 30 minutes.

[0046] If the oxygen content is stable, then oxidation is complete. Therefore, oxygen injection can be stopped, and / or the reactor can be cooled.

[0047] Saturated steam here refers to water vapor at its liquid-vapor equilibrium point (i.e., non-superheated steam). In the context of this description, it is injected at a temperature between 100°C and 170°C.

[0048] The process then includes, for example, a step of emptying the reactor.

[0049] Then, the process can be repeated on a new load in the reactor. In an exemplary implementation, the process comprises, prior to the oxidative post-treatment step, a thermolysis or vapo-thermolysis step, in a reactor, of a composite material comprising fibers and an organic matrix.

[0050] For example, the thermolysis or vapo-thermolysis step is configured to produce the recycled fibers and decompose the organic matrix into at least one organic compound.

[0051] The reactor may be the same as that in which the oxidative post-treatment step is carried out, or another reactor, upstream of that of the oxidative post-treatment step.

[0052] Also provided, according to a second aspect of the invention, is a treatment device configured to implement a method for treating a composite material as described previously.

[0053] In an exemplary embodiment, the device comprises at least one reactor.

[0054] For example, the reactor is configured to implement both a vapo-thermolysis step and an oxidative post-treatment step.

[0055] For example, the reactor has a feed inlet configured to supply, into the reactor, a composite material to be treated, and also an outlet through which so-called "recycled" fibers are recovered.

[0056] In an exemplary embodiment, the device comprises a steam superheater.

[0057] The steam superheater is, for example, configured to inject superheated steam into the reactor.

[0058] For example, the steam superheater is upstream of the reactor.

[0059] For example, the steam superheater is configured to heat water vapor to a temperature between 300°C and 600°C to be injected into the reactor. In an exemplary embodiment, the device comprises at least one sensor configured to control the oxidative post-treatment step.

[0060] The at least one sensor comprises, for example, at least one temperature sensor and / or one oxygen content sensor. Optionally, it may comprise a pressure sensor.

[0061] In an exemplary embodiment, the device comprises a control unit configured to automatically regulate the oxidizing post-treatment step, in particular based on data transmitted by the at least one sensor.

[0062] This involves, for example, an automated system for controlling the parameters of the oxidative post-treatment stage and all associated operating procedures.

[0063] In an exemplary embodiment, the device comprises a water treatment unit configured to treat running water and provide reverse osmosis water. In an exemplary embodiment, the device comprises a storage unit configured to store reverse osmosis water, and for example also configured to supply reverse osmosis water to a thermal oxidizer and / or a steam generator.

[0064] In one exemplary embodiment, the device comprises a steam generator configured to superheat the reverse osmosis water and provide saturated steam for the steam superheater.

[0065] In an exemplary embodiment, the device comprises a thermal oxidizer configured to treat vapors and gaseous products emanating from the reactor.

[0066] In an exemplary embodiment, the device comprises a primary exchanger configured to circulate osmosis water in the thermal oxidizer. The primary exchanger is for example a plate exchanger.

[0067] In an exemplary embodiment, the device comprises a secondary exchanger configured to circulate an air cooler, for example glycolated water.

[0068] For example, the secondary exchanger is connected to the primary exchanger.

[0069] Also provided, according to a third aspect of the invention, is a recycled fiber obtained by a method of treating a composite material as described above. Such a recycled fiber comprises in particular a fiber, for example of carbon, or glass, or basalt or other, and between 0 wt.% and 5 wt.%, or even between 0 wt.% and 1 wt.%, of organic compound residue.

[0070] A percentage noted “wt.%” here designates a mass percentage.

[0071] In a particular example, the recycled fiber is free of organic compound residue (which then corresponds to a content of 0 wt.%). The invention, according to an exemplary embodiment, will be well understood and its advantages will appear better on reading the detailed description which follows, given for information purposes and in no way limiting, with reference to the appended drawing in which:

[0072] Figure 1 schematically presents a processing method according to an embodiment of the invention, in a device according to an exemplary embodiment of the invention.

[0073] The value ranges are given for illustrative purposes, for a pilot installation; they would need to be adapted, mainly depending on the capacity of the reactor used.

[0074] The following description relates to a method for treating a composite material comprising carbon fibers (but it could be any other type of fiber, for example glass, or basalt, or other) and an organic compound coating at least in part one of the fibers, which comprises a step of oxidizing post-treatment of the material, implemented following a step of vapo-thermolysis of a composite material comprising fibers and an organic matrix. It could however be a simple thermolysis step. It also relates to the device configured to implement the method. For example, the thermolysis or vapo-thermolysis step is configured to produce the fibers and decompose the organic matrix into at least one organic compound.

[0075] Steam thermolysis decomposes the organic matrix of composite materials by thermal cracking in the presence of superheated steam and in the absence of oxygen. This process allows for a more complete decomposition of the polymer compared to a conventional pyrolysis process, thanks to a more oxidizing environment while reducing fiber damage thanks to less severe operating conditions (for example, the temperature can be lower, or the residence time shorter). A thermolysis reactor generally operates with a very slightly negative pressure atmosphere.

[0076] In the example of the present description, the composite materials considered used as input to the process comprise a thermosetting organic compound (for example of the epoxy or polyester or vinylester type or others) or thermoplastic (for example of the polyamide or polypropylene or polyetheretherketone or polyphenylene sulfide type or others) mainly consisting of polymerized resin, pre-impregnated or sized dry fibers. The fiber content in the laminated or pre-impregnated composite materials tested is of the order of 20-70% and up to 80%. In the case of dry fibers, this fiber content can rise to 99%.

[0077] As illustrated in Figure 1, a device configured to implement a method as described later mainly comprises a reactor 100. In the present exemplary embodiment, the reactor 100 is configured to implement both a vapo-thermolysis (or thermolysis) step and an oxidative post-treatment step.

[0078] However, in another example of implementation, a device as described here could comprise two separate reactors, one for implementing a thermolysis or vapo-thermolysis step, the other for implementing an oxidative post-treatment step.

[0079] The table below presents, for example, characteristics of a reactor suitable within the framework of the present invention:

[0080] Table: Characteristics of a vapo-thermolysis reactor

[0081] Consequently, the reactor 100 here comprises a feed inlet 1 configured to supply, into the reactor, a basic composite material to be treated, that is to say here a composite material comprising fibers and an organic matrix, and furthermore an outlet 2 through which so-called "recycled" fibers are recovered, such a fiber comprising for example a fiber and less than 5 wt.%, or even less than 1 wt.% of organic compound residue.

[0082] Here, for example, the reactor operates mainly on electricity.

[0083] The reactor 100 comprises, for example, an air injection inlet 101 and a superheated steam inlet 102.

[0084] The air injection inlet 101 is particularly useful for a treatment cycle comprising an oxidative post-treatment step, for example according to an exemplary implementation of the present invention.

[0085] For example, reactor 100 is a sealed electric furnace with forced convection controlled by depression with opening by a single swing door on one of the sides. It is mainly made up of a reaction zone with a useful volume of 3.375 m 3 The reactor is heated by six sets of electrical resistance with a total power of 118 kW.

[0086] To inject superheated steam, the device here comprises a steam superheater 103.

[0087] The table below shows, for example, characteristics of a superheater suitable for the purposes of the present invention:

[0088] Table: Characteristics of a superheater Here, for example, the steam superheater operates mainly with electricity.

[0089] The steam superheater 103 then comprises a superheated steam outlet 104 which is connected, for example by a conduit, to the superheated steam inlet 102 of the reactor 100, as well as a saturated steam inlet 118 allowing it to be supplied with steam.

[0090] For these purposes, the device comprises a water treatment unit 105.

[0091] Here, for example, the water treatment unit operates mainly on electricity.

[0092] The water treatment unit therefore has a running water supply inlet 106.

[0093] In this implementation example, the water treatment operation is carried out in a loop independent of the rest of the process. The start of this unit operation is for example controlled by the filling level of a storage unit 109. An adjustable minimum level allows for example the triggering of the water treatment devices. For example, a production cycle can only be started if the water level is higher than a limit equal to the quantity of water necessary for the production of steam during the total duration of a batch. The process is thus independent of a possible accidental water cut-off.

[0094] The water treatment operation takes place, for example, in two stages:

[0095] - Water softening with two exchange resin tanks. The lime and potassium ions contained in the mains water are exchanged with sodium ions in order to greatly limit the possibility of limescale formation during evaporation.

[0096] - Reverse osmosis to reduce the concentration of ionic species that can generate deposits.

[0097] The running water is thus treated in the water treatment unit 105 which provides on the one hand osmosis water, and on the other hand an eluate. The water treatment unit 105 therefore comprises an osmosis water outlet 107 and an eluate outlet 108.

[0098] To store the osmosis water, the device comprises the storage unit 109. Such a storage unit has a capacity of a few cubic meters, for example between 5 m 3 and 10 m 3 .

[0099] At the outlet of the storage unit 109, two pumps supply steam production and a cooling system for a thermal oxidizer 120.

[0100] The storage unit 109 consequently comprises an osmosis water inlet 110, which is connected to the osmosis water outlet 107 of the water treatment unit 105, and furthermore, the storage unit 109 comprises a first osmosis water outlet 111 configured to supply the cooling system of the thermal oxidizer 120, and a second osmosis water outlet 112 configured to supply a steam generator 113.

[0101] In order to generate saturated steam, the device therefore comprises the steam generator 113.

[0102] The table below presents for example characteristics of a steam generator suitable within the framework of the present invention:

[0103] Table: Characteristics of a steam generator

[0104] Here, the steam generator operates on electricity and natural gas, for example.

[0105] To be supplied with osmosis water, the steam generator 113 has an osmosis water inlet 114, which is therefore connected to the second osmosis water outlet 112.

[0106] The steam generator 113 also has a combustion air inlet. At the outlet, the steam generator has a liquid effluent outlet 116.

[0107] It also includes a saturated steam outlet 117, configured to supply the steam superheater 103.

[0108] The saturated steam outlet 117 is therefore connected, for example by a conduit, to the saturated steam inlet 118 of the steam superheater 103.

[0109] For example, the device then uses steam production and superheating equipment involving, for example, pharmaceutical-type steam generator water quality. This water quality is defined by equipment specifications in order to avoid fouling and damage that may occur in this equipment.

[0110] Thanks to the use of very pure water, such equipment can generate steam very quickly.

[0111] For example, the water in the steam generator has the following characteristics:

[0112] Table: Characteristics of steam generator water

[0113] Furthermore, the reactor 100 has a steam and gaseous products outlet 119.

[0114] Downstream, the device comprises a thermal oxidizer 120.

[0115] Here, the thermal oxidizer 120 operates, for example, on electricity and natural gas.

[0116] The thermal oxidizer 120 comprises a steam and gaseous products inlet 121, which is connected, for example by a conduit, to the steam and gaseous products outlet 119 of the reactor. The thermal oxidizer 120 also comprises a first osmosis water inlet 122, which is for example here connected, for example by a conduit, to the first osmosis water outlet 111 of the storage unit 109.

[0117] The thermal oxidizer 120 here comprises a second osmosis water inlet 123 configured to receive osmosis water from a primary exchanger 127.

[0118] The thermal oxidizer 120 also includes air supply inlets 124, for example quenching air and combustion air.

[0119] At the outlet, the thermal oxidizer 120 has an outlet for gaseous effluents after treatment 125.

[0120] The thermal oxidizer 120 finally comprises an osmosis water outlet 126 configured to return osmosis water to the primary exchanger 127. The thermal oxidizer 120 according to an exemplary embodiment of the invention is for example sized to have two combustion zones: a first at 900-1100°C and a second at 850-950°C.

[0121] The table below presents for example characteristics of an oxidizer suitable within the framework of the present invention:

[0122] Table: Characteristics of an oxidizer

[0123] The device therefore further comprises the primary exchanger 127 configured to circulate osmosis water in the thermal oxidizer 120.

[0124] Here, the primary exchanger operates, for example, mainly using electricity. For this purpose, the primary exchanger comprises an osmosis water inlet 128 connected, for example by a conduit, to the osmosis water outlet 126 of the thermal oxidizer 120, and an osmosis water outlet 129 connected, for example by a conduit, to the second osmosis water inlet 123 of the thermal oxidizer 120. The primary exchanger 127 also comprises here a glycol water inlet 133 and a glycol water outlet 134.

[0125] The device finally comprises a secondary exchanger 130 configured to circulate glycolated water.

[0126] Here, the secondary exchanger operates, for example, mainly using electricity. The secondary exchanger 130 here comprises a glycol water inlet 131 which is connected, for example by a conduit, to the glycol water outlet 134 of the primary exchanger 127, and a glycol water outlet 132 which is connected, for example by a conduit, to the glycol water inlet 133 of the primary exchanger 127.

[0127] In operation, upstream of any operations on the reactor 100, the method comprises a step of putting the thermal oxidizer 120 into operation and maintaining it in permanent mode.

[0128] Operations for raising and lowering the temperature of the reactor 100 thus have a low emission level, and a risk of generating discharge levels higher than the steady state of the reactor is thus very limited or even avoided. The thermal oxidizer 120 therefore operating in steady state, the method comprises a step of loading the reactor 100 with basic composite material to be treated and a step of heating the reactor, first in air, then in superheated steam to a treatment plateau temperature.

[0129] The temperature plateau is maintained for the time necessary to eliminate as much of the organic matrix as possible from the fibers of the basic composite material.

[0130] In this way, during the phase of lowering the temperature of the reactor by injection of saturated water vapor, a minimum or even no organic compound is emitted from the reactor to the thermal oxidizer 120. The operation of the oxidizer is still maintained during this phase in order to avoid as much as possible condensation of water vapor in the oxidizer.

[0131] The preparation and loading of the basic composite material is carried out in batches. For example, composite material parts to be recycled have been previously classified by type of fiber and organic compound in order to have only one type of material to process per batch. The parts can then be loaded onto a support that can be transported by forklift and / or pallet truck.

[0132] This support is configured to ensure optimal temperature and water vapor distribution throughout the reactor. It also ensures the collection of recycled fibers to ensure a certain mechanical cohesion at the end of a vapor thermolysis step.

[0133] The support is for example a metal cube with a cooperation system with a pallet truck (or a trolley); it includes a shelving system (i.e. a system of shelves) to arrange the materials and have an adequate distribution of the temperature.

[0134] In order to control the process precisely and to monitor the quality of the degradation of the organic compound, the composite material to be treated is, for example, weighed using scales before insertion into the reactor, as well as at the end of the treatment.

[0135] The support is then introduced into the reactor (previously cleaned if necessary) with the composite materials to be treated.

[0136] Each batch is, for example, made up of a maximum of 2,000 kg of composite material.

[0137] 1. Steam generation

[0138] The water vapor essential for the vapo-thermolysis reaction is produced here by the steam generator 113 and the superheater 103. The water vapor has two functions in the process described here:

[0139] - A function of inerting the reaction medium in order to limit the oxygen concentration and avoid the occurrence of an oxidation reaction in the reactor.

[0140] - A catalyst function by lowering the thermal cracking temperature of the organic compound.

[0141] The reverse osmosis water is first pumped into storage unit 109 where the oxygen content and pH are lowered.

[0142] The steam leaving the steam generator is conditioned by a separator in order to have a steam content greater than 99%.

[0143] A dry steam thus created is then expanded to approximately 100 kPa and then superheated by the superheater 103 in order to reach the desired conditions for use by the process.

[0144] Since the pressure build-up in steam equipment is very rapid (3-4 minutes for steam generator 113), this is carried out when the reactor temperature is above 160°C for example, in order to avoid any condensation in the gaseous effluent treatment chain.

[0145] The steam generator 113 operates at the same speed throughout the entire treatment batch. A steam mass flow rate is therefore a fixed parameter of the process. The steam temperature is modulated using the superheater 103 during the temperature rise and fall phases of the installation.

[0146] Saturated steam is generated with the steam generator, which is for example an instantaneous vaporization with a power of 800 to 1000 kW running on natural gas, and which is configured to carry out a first part of the superheating. Such technology also allows very rapid pressurization and is compatible with a batch process. The steam content at the steam generator outlet is greater than 99% (i.e. between 99% and 100%), which corresponds to a pharmaceutical or food standard.

[0147] Leaving the steam generator, the steam passes into the superheater 103 which is responsible for finalizing the superheating, so that the steam reaches, for example, 500°C at 101,325 Pa (pascal).

[0148] 2. Vapor thermolysis reaction

[0149] In reactor 100, the action of temperature in an atmosphere made inert by superheated water vapor allows thermal cracking of the organic matrix in the form of a gaseous product. A continuous oxygen measurement is provided in reactor 100 during the process, as well as an emergency nitrogen injection if the oxygen concentration becomes at least equal to 8%. The critical points of this equipment for the quality of the product are the homogeneity of the temperature and the flow of water vapor. The composites being loaded onto a loading support, this is configured so as not to generate dry or cold zones in the reactor.

[0150] A controllable mixing fan allows homogenization to be achieved at the plate temperature to be approximately 1.5°C. Superheated steam is continuously injected into the reactor to ensure inerting and produce the atmosphere necessary for vapo-thermolysis. This steam and the gaseous thermolysis products are continuously extracted from the reactor using a hot gas extractor with a remote belt drive and controlled by the reactor's vacuum value.

[0151] Water vapor is injected when the reactor temperature is above the condensation temperature at 700 kPa (160°C). The temperature rise then continues according to the planned plateau temperatures, between 300 and 600°C. The total duration of these temperature plateaus is, for example, between 2 hours and 4 hours. The ratio of the injected water vapor flow rate to the mass of the composite is, for example, between 0.5 and 1.5.

[0152] After the temperature plateau, the reactor heating is stopped, the reactor is cooled by injecting saturated steam then ambient air and nitrogen (if necessary). When the temperature reaches 140°C, the reactor door can be opened. Cooling then continues to 50-60°C, at which temperature the loading support can be removed from the reactor.

[0153] 3. Post-oxidative treatment

[0154] The treatment method according to the invention allows, in addition to a thermolysis or vapo-thermolysis treatment, to implement a post-treatment. This additional treatment is called “oxidative post-treatment”.

[0155] Indeed, some waste is partly made up of organic compounds that cannot be completely eliminated by simply carrying out thermolysis or vapo-thermolysis and therefore require a second treatment stage: the oxidative post-treatment stage. The oxidative post-treatment stage essentially consists of injecting a controlled quantity of oxygen into the reactor, which is maintained at a defined and controlled temperature in order to oxidize the organic compounds still present on a fiber to transform them into CO and CO2.

[0156] It allows the removal of a part of the organic compound which is not degraded, or not degradable, or not entirely degradable, by thermolysis or vapo-thermolysis, whatever the operating conditions, as well as, where appropriate, other organic compounds (such as tars, chars or other residues) which may have been obtained by transformation of the organic compound of the composite material during the prior thermolysis or vapo-thermolysis step. For this, the injection of oxygen is carried out by injecting air inside the reaction medium, for example by means of a dedicated valve.

[0157] This injection can take place:

[0158] - After a complete thermolysis or vapo-thermolysis reaction (everything that could be degraded by thermolysis or vapo-thermolysis has been);

[0159] - With or without maintaining a steam injection in parallel (for example an air injection which therefore includes 1'02);

[0160] - Preferably between 300 and 600°C;

[0161] - For a duration that can generally be between 20 min and 6 h. The choice of the different methods depends on the material treated and the desired residual organic compound level. Preliminary laboratory analyses allow, for example, to estimate the quantities of materials to be degraded and therefore the appropriate treatment (duration and O2 flow rate for example).

[0162] The end of the oxidation reaction is, for example, measured by a stabilization of the O2 level at the reactor outlet, for example around 20-21%.

[0163] Once a temperature plateau has been achieved, for example at a temperature between 400°C and 600°C, and therefore a thermolysis / vapo-thermolysis reaction has been completed, three examples of implementation according to the invention are described below: According to a first example of implementation, the method comprises a step of reducing the temperature in the reactor then a step of maintaining it at this temperature to finally cut off the steam injection and introduce only air into the reaction medium, for example at a controlled flow rate. To do this, for example, initially the superheater is stopped in order to inject saturated steam (for example at 100°C) into the reactor and carry out cooling. Once the temperature of the reaction medium has been reached, the steam injection is stopped, the temperature is maintained, for example by the action of heating resistors in the reactor, and ambient air is introduced into the reactor.For example, the air injection flow rate is regulated based on the O2 content at the reactor outlet. Once this rate reaches 20-21%, the oxidative post-treatment stage is complete and, for example, saturated steam is injected again to cool the product.

[0164] According to a second example of implementation, the reaction medium is not cooled because some compounds require the oxidative post-treatment step to take place at 500°C. However, unlike the first example, an injection of superheated steam at approximately 500°C is retained in order to renew the reaction volume more quickly and therefore maintain a stable temperature. For example, ambient air is injected into the reaction medium at 500°C by no longer regulating on an O2 output rate (for example the oxygen is diluted in the steam) but by injecting a constant air flow rate for a defined holding time. Indeed, the mass of organic compound to be treated by oxidative post-treatment makes it possible to define the mass of O2 to be injected and therefore determine which air flow rate to introduce for which duration.As with the first implementation example, once the reaction is complete, the air injection can be stopped, as can the heating of the steam, to proceed with cooling the product using the saturated steam.

[0165] According to a third example of implementation, the first and second examples are combined, that is to say, initially, the method comprises a cooling step and then a step of slow heating of the reaction medium, during the oxidative post-treatment step, for example in order to control an air flow rate but also the oxidative post-treatment reaction temperature. However, this example of implementation takes longer and requires more energy.

[0166] These implementation examples are generally implemented directly after the thermolysis or vapo-themnolysis reaction (before the temperature decreases and the reactor is opened). However, they can also be carried out on an independent cycle (after complete cooling and a new temperature increase). However, this then induces an additional energy cost (the temperature must be increased at the start of the second cycle).

[0167] 4. Treatment of gaseous products

[0168] The gaseous products from vapo-thermolysis are treated by total decomposition using thermal oxidation. This equipment consists of a low NOx burner, two combustion chambers and a SNCR (selective non-catalytic reduction) NOx treatment using urea spray.

[0169] The thermolysis gases from the thermolysis reaction are mainly composed of organic species (C, H, O, N), they are treated by thermal oxidation (reaction with oxygen at temperature) to form carbon dioxide (CO2), water (H2O) and nitrogen oxides (NOx). In order to comply with the emission limits for nitrogen oxides, an example of a combination of emission control technologies has been implemented with the following elements:

[0170] • A LowNOx burner that generates little NOx during the oxidation of organic species.

[0171] • A double oxidation chamber configured to allow total oxidation of organic compounds without oxidizing nitrogen.

[0172] • A reduction of residual NOx by "non-catalytic reduction" with a spray of urea in the gas flow at temperature. The urea flow will be oversized in relation to the quantity of NOx to be treated, thus allowing a maximum reduction.

[0173] The first oxidation chamber is controlled in sub-stoichiometry at very high temperature and in order to greatly limit the appearance of nitrogen oxide, this equipment is equipped with a double jacket. This morphology allows the metal structure of the primary oxidation chamber to be cooled. A ramp spraying 20 to 50 m 3 / h of osmosis water is installed to maintain the temperature of the structure within the permissible limits for the material. The cooling water is collected at the bottom of the double jacket, then pumped to a plate exchanger, the primary exchanger 127, to be cooled and re-injected into the oxidizer 120 for a new cooling cycle.

[0174] A counter-current flow of glycolated water, for example at a flow rate of between 30 m 3 / h and 60 m 3 / h, also passes through the plate exchanger 127 to finally evacuate the excess calories thanks to a closed-circuit air cooler located outside.

[0175] The gaseous discharge into the atmosphere is cooled by injection of fresh air (for example between 5000 and 25000 Nm 3 / h) at the outlet of the thermal oxidizer 120 in order to limit the temperature in the chimney. The temperature is for example between 300 and 400°C for a steel chimney, for example with a diameter of the order of 900 mm to 1500 mm, which makes it possible for example to limit the ejection speed and / or noise pollution.

[0176] The treatment of gaseous effluents consists of open flame oxidation of all organic species present. The guidelines for this type of treatment recommend passing the organic compounds to a temperature above 850°C for a minimum of 2 seconds.

[0177] The thermal oxidizer 120 according to an exemplary embodiment of the invention is for example sized to have two combustion zones: a first at 900-1100°C and a second at 850-950°C, as described previously.

[0178] 5. Unloading, quality control and packaging

[0179] Once the reactor has cooled to a temperature below 50-60°C, it is opened and unloaded using a forklift, for example. The loading support with the fibers is then weighed using the same scale as during loading in order to check the degradation rate of the organic compound in the composite. The fibers are then removed from the loading cart and placed in a transfer area. A sample of the recycled fibers obtained is taken to check the quality of the thermolysis reaction (absence of residual organic compound on the recycled fibers). If this preliminary check proves positive, then mechanical quality checks of the rCF are carried out. The recycled fibers then undergo the following operations:

[0180] - Sorting: at the outlet of the vapor thermolysis reactor, the carbon fibers are separated from other waste (bolts, etc.);

[0181] - Packaging and storage: the sorted rCF are packaged and then stored in cardboard boxes, bags, IBCs or big bags; - Shipping: when ordered, the carbon fiber is packaged in cardboard boxes, bags, IBCs or big bags according to customer needs.

Claims

DEMANDS 1. A process for treating a composite material comprising reinforcing fibers and an organic compound coating at least part of one of the fibers, the process comprising an oxidative post-treatment step of the material in a reactor (100), the oxidative post-treatment step comprising: - a stage of heating the reactor (100) to a first temperature between 300°C and 600°C; - an oxygen injection step into the reactor (100) configured to produce an oxygen content of between 2% and 15% of a reaction volume of the reactor, - a step of injecting steam into the reactor (100); this steam being superheated to a temperature between 300°C and 600°C, for example to the first temperature, and - an oxidation step of the organic compound into carbon monoxide (CO) and / or carbon dioxide (CO2).

2. Method according to claim 1, wherein oxygen is injected into the reactor (100) at an ambient temperature, for example which is between 15°C and 50°C.

3. Method according to claim 1, wherein oxygen is injected into the reactor (100) after being heated, for example to a temperature between 50°C and 600°C, for example between 300°C and 600°C, for example to the first temperature.

4. A method according to any one of claims 1 to 3, wherein oxygen is injected into the reactor (100) for a period of between 10 minutes and 6 hours.

5. A method according to any one of claims 1 to 4, wherein The post-oxidative treatment stage includes: - A temperature reduction step in the reactor (100), from the first temperature to a second temperature, the second temperature being between 300°C and 500°C; - A stage of maintaining the second temperature for a period of between 10 minutes and 6 hours; and - A step of introducing oxygen into the reactor (100).

6. A process according to claim 5, wherein the oxidative post-treatment step comprises a step of reducing steam injection into the reactor (100).

7. A method according to any one of claims 5 or 6, wherein the oxygen introduction step includes a step of regulating the injection flow rate as a function of an oxygen content at the outlet of the reactor (100).

8. A method according to any one of claims 5 to 7, wherein the temperature reduction step, from the first temperature to the second temperature, includes a temperature reduction step of the superheated steam injected into the reactor (100).

9. A process according to any one of claims 1 to 8, wherein the oxidative post-treatment step further comprises a step of simultaneous or alternating the flow rates of steam and oxygen to maintain the temperature and oxygen content of the reaction medium, respectively, between 300°C and 600°C and 2% to 15%.

10. A method according to any one of claims 1 to 9, comprising a step of measuring the quantity of oxygen at the outlet of the reactor (100); and if an oxygen content is stable, the method comprises: - A step to stop oxygen injection; and / or - A steam heating shutdown step; and / or - A reactor cooling stage (100) comprising a saturated steam injection stage.

11. A process according to any one of claims 1 to 10, comprising, prior to the oxidative post-treatment step, a thermolysis or vapo-thermolysis step, in a reactor, of a composite material comprising fibers and an organic matrix.

12. Processing device configured to implement a process for processing a composite material according to any one of claims 1 to 11, the device comprising a reactor (100) and a steam superheater (103), upstream of the reactor (100), the steam superheater (103) being configured to raise water vapor to a temperature between 300°C and 600°C for injection into the reactor (100).

13. Device according to claim 12, characterized in that it comprises at least one sensor configured to control the oxidative post-treatment step, and a control unit configured to automatically regulate the oxidative post-treatment step based on data transmitted by at least one sensor.

14. Device according to any one of claims 12 or 13, characterized in that it comprises a water treatment unit (105) configured to treat tap water and provide reverse osmosis water.

15. Device according to any one of claims 12 to 14, characterized in that it comprises a storage unit (109) configured to store reverse osmosis water.

16. Device according to any one of claims 14 or 15, characterized in that it comprises a steam generator (113) configured to superheat the reverse osmosis water and provide saturated steam for the steam superheater (103).

17. Device according to any one of claims 12 to 16, characterized in that it comprises a thermal oxidizer (120) configured to treat vapors and gaseous products emanating from the reactor (100).

18. Device according to any one of claims 12 to 17, characterized in that it comprises a primary exchanger (127) configured to circulate osmosis water in the thermal oxidizer (120).

19. Device according to any one of claims 12 to 18, characterized in that it comprises a secondary exchanger (130) configured to circulate an air-cooled condenser, for example glycol water.

20. Recycled fiber obtained by a process of treating a composite material according to any one of claims 1 to 11, the recycled fiber comprising a fiber and between 0% and 5% by mass of residual organic compound.

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