Process for treating composite material waste, device for implementing the process, and recycled fiber obtained.

Abstract

A process for treating a composite material comprising reinforcing fibers and an organic compound, including an oxidative post-treatment step of the composite material comprising: a step of heating the reactor (100) to a first temperature between 300°C and 600°C; a step of injecting oxygen into the reactor configured to produce an oxygen content between 2% and 15% of the reactor's reaction volume; a step of injecting steam into the reactor; this steam being superheated to a temperature between 300°C and 600°C; and a step of oxidizing the organic compound to CO and / or CO2. A treatment device configured to implement the process and the resulting recycled fiber are shown. Figure for the abstract: Fig. 1

Description

Title of the invention: Process for treating waste composite materials, device for implementing the process and recycled fiber obtained

[0001] The present invention relates to a process for treating composite material waste.

[0002] It relates in particular to a process for treating a fiber-reinforced composite material, such as, for example, mainly carbon fibers, or glass fibers, or basalt fibers or other (manufacturing waste, end-of-life elements from the aeronautics, automotive, nautical industries, etc.), that is to say, a material comprising fibers coated at least in part with an organic compound.

[0003] It also relates to a processing device configured to implement the process.

[0004] It finally relates to a recycled fiber obtained by the process.

[0005] A composite material such as considered here 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 coated.

[0006] To recycle such a material, one possibility is to separate the matrix and the fibers, i.e. to 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.

[0007] For this purpose, a composite material can undergo a thermolysis or vapo-thermolysis process.

[0008] A vapor-thermolysis process, for example, allows the organic matrix of composite materials to be decomposed 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 constituting the matrix compared to a conventional pyrolysis process, thanks to a more oxidizing environment, while reducing fiber damage due 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 an atmosphere under very slight negative pressure.

[0009] The fibers obtained after vapor-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 fabric, staple fiber yarn, threads, etc.), because these products These semi-finished products can then be used later as raw material to produce a composite material based on recycled material. These semi-finished products are thus intended, for example, for the manufacture, by third-party manufacturers, of new composite materials, for example for the automotive, shipbuilding, or even aeronautical or energy sectors.

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

[0011] Consequently, undesirable organic compounds may remain present on a fiber.

[0012] The present invention thus aims to propose a process for treating composite materials that improves the removal of organic compounds on reinforcing fibers.

[0013] To this end, according to a first aspect of the invention, a process for treating a composite material comprising reinforcing fibers and an organic compound coating at least partially one of the fibers is proposed, the process comprising an oxidative post-treatment step of the composite material in a reactor, the oxidative post-treatment step comprising: - a stage of heating the reactor to an initial temperature between 300°C and 600°C; - an oxygen (O2) injection step into the reactor 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 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).

[0014] Oxidative post-treatment therefore refers here to an oxidation step of the material which is implemented after a thermolysis (or vapo-thermolysis) type treatment, in a reactor.

[0015] 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.

[0016] An oxidative post-treatment step here consists of injecting a controlled amount of oxygen into a reactor which is maintained at a defined and controlled temperature.

[0017] In the context of the composite material treatment considered here, this post-oxidative 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).

[0018] Such a step thus makes it possible to remove part of the organic compound which is not degraded, or not degradable, or not entirely degradable, by thermolysis or vapo-thermolysis, regardless of the operating conditions, as well as, where applicable, 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.

[0019] A step of injecting steam into the reactor during the oxidative post-treatment step has the particular advantage of allowing the oxidative post-treatment reaction to be stabilized, for example by stabilizing the temperature of the reactor.

[0020] It also allows, for example, limiting the risk of fire starting; without steam, combustion problems can occur.

[0021] In one example of implementation, the step of injecting oxygen into the reactor may include an injection of pure oxygen, or of any gas containing oxygen, such as ambient air, or a nitrogen-dioxygen complex.

[0022] In one embodiment, the reactor in which the oxidative post-treatment step is carried out is the same reactor as the one in which the thermolysis or steam-thermolysis is performed. However, it may be a different reactor, which would then be downstream of the thermolysis or steam-thermolysis reactor.

[0023] In one example of implementation, oxygen is injected into the reactor at an ambient temperature, for example which is between 15 and 50°C.

[0024] In another example of implementation, 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.

[0025] In one example of implementation, oxygen is injected into the reactor for a period of between 10 minutes and 6 hours.

[0026] Oxygen is for example 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.

[0027] The flow rate can therefore be very variable, for example between 10 and 1000 m3 / h.

[0028] In one example of implementation, the oxidative post-treatment step comprises: - 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); - A stage of maintaining the second temperature in the reactor for a period of between 10 minutes and 6 hours; and - A step of introducing oxygen (O2) into the reactor.

[0029] In one example of implementation, the oxidative post-treatment step may further include a step for reducing steam injection into the reactor.

[0030] When steam injection is reduced, the steam injection flow rate is lower, and depends for example on the size of the reactor (for example its internal volume, and / or the amount of material to be treated present in the reactor).

[0031] In one example of implementation, the steam injection can be stopped (i.e. a flow rate of 0 m3 / hour).

[0032] In practice, the temperature in the reactor can often fluctuate because an oxidative post-treatment reaction can be exothermic.

[0033] However, the post-oxidative treatment can be carried out, at least in part, after the temperature reduction step, or during the temperature reduction step.

[0034] In one example of implementation, the oxidative post-treatment step may further include at least one step of simultaneous or alternating dosing of steam and O2 flow rates to maintain the temperature and O2 content of the reaction medium, respectively between 300°C and 600°C and 2% to 15%.

[0035] In one example of implementation, the temperature reduction step, from the first temperature to the second temperature, includes a step of reducing the temperature of the superheated steam injected into the reactor.

[0036] In one example of implementation, the process includes a step of measuring a quantity of oxygen at the outlet of the reactor.

[0037] In one example of implementation, the step of introducing oxygen into the reactor includes a step of regulating the injection flow rate according to an oxygen content at the outlet of the reactor.

[0038] For example, if the oxygen content is stable, the process comprises: - A step to stop oxygen injection; and / or - A steam heating shutdown step; and / or - A reactor cooling stage including a saturated steam injection stage.

[0039] The term "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 for 10 to 30 minutes.

[0040] If the oxygen content is stable, then the oxidation is complete. Therefore, the oxygen injection can be stopped, and / or the reactor can be cooled.

[0041] Saturated vapor here refers to water vapor located at its liquid-vapor equilibrium point (it is therefore non-superheated vapor).

[0042] In the context of this description, it is injected at a temperature between 100°C and 170°C.

[0043] The process then includes, for example, a step of emptying the reactor.

[0044] Then, the process can be repeated on a new load in the reactor.

[0045] In one example of implementation, the process includes, 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.

[0046] For example, the thermolysis or vapo-thermolysis step is configured to produce recycled fibers and decompose the organic matrix into at least one organic compound.

[0047] The reactor may be the same as that in which the oxidative post-treatment step is implemented, or another reactor, upstream of that of the oxidative post-treatment step.

[0048] Also proposed, according to a second aspect of the invention, is a processing device configured to implement a process for processing a composite material as described above.

[0049] In one embodiment, the device comprises at least one reactor.

[0050] For example, the reactor is configured to implement both a vapo-thermolysis step and an oxidative post-treatment step.

[0051] For example, the reactor has a feed inlet configured to supply, in the reactor, a composite material to be treated, and also an outlet through which so-called "recycled" fibers are recovered.

[0052] In one embodiment, the device includes a steam superheater.

[0053] The steam superheater is configured, for example, to inject superheated steam into the reactor.

[0054] For example, the steam superheater is upstream of the reactor.

[0055] For example, the steam superheater is configured to bring water vapor to a temperature between 300°C and 600°C to be injected into the reactor.

[0056] In one embodiment, the device includes at least one sensor configured to control the oxidative post-treatment step.

[0057] At least one sensor includes, for example, at least one temperature sensor and / or one oxygen content sensor. Optionally, it may include a pressure sensor.

[0058] In one embodiment, the device includes a control unit configured to automatically regulate the oxidative post-treatment step, in particular based on data transmitted by at least one sensor.

[0059] This is, for example, an automated system for controlling the parameters of the oxidative post-treatment stage and all associated operating procedures.

[0060] In one embodiment, the device includes a water treatment unit configured to treat tap water and provide reverse osmosis water.

[0061] In one embodiment, the device includes 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.

[0062] In one embodiment, the device includes a steam generator configured to superheat the reverse osmosis water and provide saturated steam for the steam superheater.

[0063] In one embodiment, the device includes a thermal oxidizer configured to treat vapors and gaseous products emanating from the reactor.

[0064] In one embodiment, the device includes a primary exchanger configured to circulate reverse osmosis water in the thermal oxidizer.

[0065] The primary exchanger is, for example, a plate exchanger.

[0066] In one embodiment, the device includes a secondary exchanger configured to circulate an air-cooled condenser, for example glycol water.

[0067] For example, the secondary exchanger is connected to the primary exchanger.

[0068] A recycled fiber is also proposed according to a third aspect of the invention. obtained by a composite material processing method as described above.

[0069] 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 residue of organic compound.

[0070] In a particular example, the recycled fiber is free of residue of organic compound (which then corresponds to a content of 0 wt.%).

[0071] The invention, according to an exemplary embodiment, will be better understood and its advantages will become more apparent upon reading the following detailed description, given by way of example and in no way limiting, with reference to the accompanying drawing in which:

[0072] Fig. 1 schematically presents a treatment process according to an embodiment of the invention, in a device according to an example of an embodiment of the invention.

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

[0074] The following description relates to a process for treating a composite material comprising carbon fibers (but it could be any other type of fiber, for example glass, basalt, or other) and an organic compound coating at least part of one of the fibers, which includes an oxidative post-treatment step of the material, carried out following a vapor-thermolysis step of a composite material comprising fibers and an organic matrix. It could, however, be of a simple thermolysis step. It also concerns the device configured to implement the process.

[0075] 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.

[0076] Vapor-thermolysis allows the organic matrix of composite materials to be decomposed by thermal cracking in the presence of superheated steam and in the absence of oxygen. This process provides more complete polymer decomposition compared to conventional pyrolysis, thanks to a more oxidizing environment, while reducing fiber damage due to less severe operating conditions (for example, the temperature can be lower, or the residence time shorter). A thermolysis reactor generally operates with a slightly negative pressure atmosphere.

[0077] In the example of this description, the composite materials considered as input to the process comprise a thermosetting organic compound (e.g., epoxy, polyester, vinyl ester, or other) or a thermoplastic compound (e.g., polyamide, polypropylene, polyetheretherketone, polyphenylene sulfide, or other) mainly consisting of polymerized resin, prepregs, or coated dry fibers. The fiber content in the tested laminated or prepreg composite materials is on the order of 20–70% and up to 80%. In the case of dry fibers, this fiber content can reach up to 99%.

[0078] As illustrated in [Fig.1], a device configured to implement a process as described later comprises mainly a reactor 100.

[0079] In the present embodiment, reactor 100 is configured to implement both a vapo-thermolysis (or thermolysis) step and an oxidative post-treatment step.

[0080] However, in another example of implementation, a device such as described here could comprise two separate reactors, one to implement a thermolysis or vapo-thermolysis step, the other to implement an oxidative post-treatment step.

[0081] The table below presents, for example, characteristics of a suitable reactor within the scope of the present invention: Parameters Value Maximum composite mass / batch 1600 kg Estimated volume 3-4 m³ (smallest dimension > 1.5 m) Temperature 300 - 600°C Operating pressure -20 - -200 Pa Heating power 100 - 150 kW Heating rate Approximately 4°C / min Holding time 1-8 hours Cooling Saturated steam / nitrogen / air Maximum extraction flow rate 5000 - 7000 m³ / h max Outlet pressure 100 - 2000 Pa

[0082] Table: Characteristics of a vapor-thermolysis reactor

[0083] Consequently, the reactor 100 here includes a feed inlet 1 configured to supply, in the reactor, a basic composite material to be treated, i.e. 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.

[0084] Here, the reactor operates primarily on electricity, for example.

[0085] The reactor 100 includes, for example, here an air injection inlet 101 and a superheated steam inlet 102.

[0086] The air injection inlet 101 is particularly useful for a treatment cycle comprising an oxidizing post-treatment step, for example according to an embodiment of the present invention.

[0087] For example, reactor 100 is a sealed, forced-convection, negative-pressure electric furnace with a single-hinged door opening on one side. It mainly consists of a reaction zone with a usable volume of 3.375 m³. The reactor is heated by six sets of electric resistance heaters with a total power of 118 kW.

[0088] To inject superheated steam, the device here includes a steam superheater 103.

[0089] The table below presents, for example, characteristics of a suitable superheater within the scope of the present invention: Parameters Value Superheater electrical power 200 - 300 kW Superheater outlet temperature 160 - 600°C Superheater outlet pressure 100 - 200 kPa

[0090] Table: Characteristics of a superheater

[0091] Here, the steam superheater operates, for example, mainly on electricity.

[0092] The steam superheater 103 then includes a superheated steam outlet 104 which is connected, for example by a conduit, to the superheated steam inlet 102 of reactor 100, as well as a saturated steam inlet 118 allowing it to be supplied with steam.

[0093] For these purposes, the device includes a water treatment unit 105.

[0094] Here, the water treatment unit, for example, operates mainly on electricity.

[0095] The water treatment unit therefore includes a fresh water supply inlet 106.

[0096] In this implementation example, the water treatment system operates in a closed loop, independent of the rest of the process. The start of this unit operation is, for example, controlled by the fill level of a storage unit 109. An adjustable minimum level allows, for example, the activation of the water treatment components. For example, a production cycle can only be started if the water level is above a limit equal to the quantity of water required for steam production during the entire duration of a batch. The process is thus independent of any accidental water supply interruption.

[0097] The water treatment operation takes place, for example, in two stages: - Water softening with two resin exchange tanks. The calcium 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. - Reverse osmosis to reduce the concentration of ionic species that can generate a deposit.

[0098] The tap water is thus treated in the water treatment unit 105, which provides, on the one hand, reverse osmosis water, and on the other hand, an eluate. The water treatment unit 105 therefore includes a reverse osmosis water outlet 107 and an eluate outlet 108.

[0099] To store the reverse osmosis water, the device includes the storage unit 109.

[0100] Such a storage unit has a capacity of a few cubic meters, for example between 5 m3 and 10 m3.

[0101] At the outlet of the storage unit 109, two pumps supply a steam production and a cooling system of a thermal oxidizer 120.

[0102] The storage unit 109 consequently includes 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 includes 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.

[0103] In order to generate saturated steam, the device therefore includes the steam generator 113.

[0104] The table below presents, for example, characteristics of a suitable steam generator within the scope of the present invention: Parameters Value Steam generator power supply Natural gas 800 - 1000 kW Maximum steam flow rate 800 - 1500 kg / h Steam generator outlet temperature 150- 180 °C Steam generator outlet pressure 600 - 900 kPa Electrical power 5 - 15 kW Steam quality 99 - 100%

[0105] Table: Characteristics of a steam generator

[0106] Here, the steam generator operates, for example, on electricity and natural gas.

[0107] To be supplied with reverse osmosis water, the steam generator 113 includes a osmosis water inlet 114, which is therefore connected to the second osmosis water outlet 112.

[0108] The steam generator 113 also includes a combustion air inlet 115.

[0109] At the outlet, the steam generator includes a liquid effluent outlet 116.

[0110] It also includes a saturated steam outlet 117, configured to supply the steam superheater 103.

[0111] The saturated steam outlet 117 is therefore connected, for example by a conduit, to the saturated steam inlet 118 of the steam superheater 103.

[0112] For example, the device then uses steam production and superheating equipment involving, for example, pharmaceutical-grade steam generator water. This water quality is defined by equipment specifications to prevent fouling and damage that may occur in this equipment.

[0113] Thanks to the use of very pure water, such equipment makes it possible to generate steam very quickly.

[0114] The water in the steam generator has, for example, the following characteristics: Parameters Values ​​Acid conductivity (25 °C) < 2.5 pS / cm Na+K < 0.010 mg / 1 Fe < 0.020 mg / 1 Cu < 0.003 mg / 1 Si < 0.020 mg / 1 TOC <0.2 02 < 2 ppb PH >9.2

[0115] Table: Characteristics of the steam generator water

[0116] Furthermore, reactor 100 includes a steam and gaseous product outlet 119.

[0117] Downstream, the device includes a thermal oxidizer 120.

[0118] Here, the thermal oxidizer 120 operates for example on electricity and natural gas.

[0119] The thermal oxidizer 120 has a steam and gaseous product inlet 121, which is connected, for example by a conduit, to the steam and gaseous product outlet 119 of the reactor.

[0120] The thermal oxidizer 120 also includes 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.

[0121] The thermal oxidizer 120 here includes a second osmosis water inlet 123 configured to receive osmosis water from a primary exchanger 127.

[0122] The thermal oxidizer 120 also includes air supply inlets 124, for example quenching air and combustion air.

[0123] At the outlet, the thermal oxidizer 120 includes a gaseous effluent outlet after treatment 125.

[0124] The thermal oxidizer 120 finally includes an osmosis water outlet 126 configured to return osmosis water to the primary exchanger 127.

[0125] The thermal oxidizer 120 according to an example embodiment of the invention is for example dimensioned to have two combustion zones: a first at 900-1100°C and a second at 850-950°C.

[0126] The table below presents, for example, characteristics of a suitable oxidizer within the scope of the present invention: Parameters Value Natural gas burner power 0.5 - 1.5 MW Thermolysis gaseous product burner power 0.1 - 1.5 MW Nominal primary chamber temperature 900-1100 °C Nominal secondary chamber temperature 850 - 950 °C Packing Refractory fibers and bricks Flue gas velocity 10 - 20 m / s

[0127] Table: Characteristics of an oxidizer

[0128] The device therefore further comprises the primary exchanger 127 configured to circulate osmosis water in the thermal oxidizer 120.

[0129] Here, the primary heat exchanger operates, for example, mainly on electricity.

[0130] For this purpose, the primary exchanger includes 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.

[0131] The primary exchanger 127 also includes here a glycol water inlet 133 and a glycol water outlet 134.

[0132] The device finally includes a secondary exchanger 130 configured to circulate glycol water.

[0133] Here, the secondary exchanger operates, for example, mainly on electricity.

[0134] The secondary exchanger 130 here includes 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.

[0135] In operation, upstream of all operations on reactor 100, the process includes a step of starting up and maintaining in steady state the thermal oxidizer 120.

[0136] Temperature rise and fall operations of reactor 100 thus have a low emission level, and the risk of generating emission levels higher than the steady state of the reactor is thus very limited or even avoided.

[0137] The thermal oxidizer 120 therefore operating in steady state, the process includes a step of loading the reactor 100 with basic composite material to be treated and a step of heating the reactor, first under air, then under superheated steam up to a treatment plateau temperature.

[0138] The temperature plateau is maintained for the time necessary to eliminate a maximum of the organic matrix on the fibers of the base composite material.

[0139] In this way, during the phase of lowering the temperature of the reactor by injection of saturated steam, a minimum or even no organic compound is emitted from the reactor to the thermal oxidizer 120.

[0140] The operation of the oxidizer is nevertheless maintained during this phase in order to avoid as much as possible the condensation of water vapor in the oxidizer.

[0141] The preparation and loading of the base composite material is carried out in batches. For example, composite parts to be recycled have been pre-sorted by fiber type and organic compound so that only one type of material is processed per batch. The parts can then be loaded onto a transportable support using a forklift and / or pallet jack.

[0142] This support is configured to ensure optimal temperature and steam distribution throughout the reactor. It also ensures the collection of recycled fibers to provide some mechanical cohesion at the end of a steam-thermolysis step.

[0143] The support is for example a metal cube with a cooperation system with a pallet truck (or trolley); it includes a shelving system (i.e. a system of shelves) for arranging the materials and having an adequate temperature distribution.

[0144] In order to control the process precisely and to control the quality of the degradation of the organic compound, the composite material to be treated is for example weighed using load cells before insertion into the reactor, as well as at the exit of the treatment.

[0145] The support is then introduced into the reactor (previously cleaned if necessary) with the composite materials to be treated.

[0146] Each batch is for example composed of a maximum of 2,000 kg of composite material. 1. Steam generation

[0147] The steam essential for the steam-thermolysis reaction is produced here by the steam generator 113 and the superheater 103. The steam has two functions in the process described here: - An inerting function of the reaction medium in order to limit the oxygen concentration and prevent the occurrence of oxidation reactions in the reactor. - A catalytic function by lowering the thermal cracking temperature of the organic compound.

[0148] The reverse osmosis water is first pumped into the storage unit 109 in which the oxygen content and pH are lowered.

[0149] The steam exiting the steam generator is conditioned by a separator in order to have a steam quality greater than 99%.

[0150] A dry vapor thus created is then expanded to about 100 kPa and then superheated by the superheater 103 in order to reach the conditions desired for use by the process.

[0151] Since the pressure rise of the steam equipment is very rapid (3-4 minutes for the steam generator 113), this is carried out when the temperature of the reactor is above 160°C for example, in order to avoid any condensation phenomenon in the gaseous effluent treatment chain.

[0152] The steam generator 113 operates at the same speed throughout the entire processing batch. A steam mass flow rate is therefore a fixed parameter of the process. The steam temperature is modulated by the superheater 103 during the heating and cooling phases of the installation.

[0153] Saturated steam is generated by a steam generator, which is, for example, an instantaneous steam generator with a power output of 800 to 1000 kW, operating on natural gas, and configured to perform the initial superheating. This technology also allows for very rapid pressurization and is compatible with a batch process. The steam quality at the steam generator outlet is greater than 99% (i.e., between 99% and 100%), which corresponds to a pharmaceutical or food standard.

[0154] Upon exiting 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). 2. Vapor-thermolysis reaction

[0155] In reactor 100, the action of temperature in an atmosphere made inert by superheated water vapor allows the thermal cracking of the organic matrix in the form of a gaseous product.

[0156] Continuous oxygen monitoring is provided in reactor 100 during the process, as well as an emergency nitrogen injection if the oxygen concentration reaches or exceeds 8%. The critical points of this equipment for product quality are the homogeneity of temperature and steam flow. Since the composites are loaded onto a loading support, this support is configured to avoid creating dry or cold zones within the reactor.

[0157] A controllable mixing fan allows homogenization to be achieved at the plateau temperature, within ±1.5°C. Superheated steam is continuously injected into the reactor to ensure inerting and to produce the atmosphere necessary for steam thermolysis. This steam and the gaseous products of thermolysis are continuously extracted from the reactor by means of a hot gas extractor with remote belt drive and controlled by the reactor vacuum value.

[0158] Steam is injected when the reactor temperature exceeds the condensation temperature of 700 kPa (160°C). The temperature ramp then continues according to the planned plateau temperatures, which range from 300 to 600°C. The total duration of these temperature plateaus is, for example, between 2 and 4 hours. The ratio of injected steam flow rate to the mass of the composite is, for example, between 0.5 and 1.5.

[0159] After the temperature plateau is reached, the reactor heating is stopped, and the reactor is cooled by injecting saturated steam followed by 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. 3. Post-oxidant treatment

[0160] The treatment process according to the invention allows, in addition to a thermolysis or vapo-thermolysis treatment, the implementation of a post-treatment. This additional treatment is called "oxidative post-treatment".

[0161] Indeed, some waste consists partly of organic compounds that cannot be completely eliminated by thermolysis or steam thermolysis alone and therefore requires a second treatment step: the oxidative post-treatment step. The oxidative post-treatment step 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, transforming them into CO and CO2.

[0162] It allows the removal of part of the organic compound which is not degraded, or not degradable, or not entirely degradable, by thermolysis or vapo-thermolysis, regardless of the operating conditions, as well as, where applicable, 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.

[0163] For this purpose, the oxygen injection is carried out by injecting air into the reaction medium, for example by means of a dedicated valve.

[0164] This injection can take place:

[0165] - After a complete thermolysis or vapor-thermolysis reaction (everything that could have (to be degraded by thermolysis or vapo-thermolysis has been);

[0166] - With or without maintaining a parallel steam injection (for example a air injection which therefore includes 1'02);

[0167] - Preferably between 300 and 600°C;

[0168] - For a duration that can generally be between 20 min and 6 h.

[0169] The choice of different modalities depends on the material being treated and the desired level of residual organic compound. Preliminary laboratory analyses make it possible, for example, to estimate the quantities of material to be degraded and therefore the appropriate treatment (duration and O2 flow rate, for example).

[0170] The end of the oxidation reaction is measured for example by a stabilization of the O2 level at the reactor outlet, for example around 20-21%.

[0171] Once a temperature plateau has been reached, 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:

[0172] According to a first embodiment, the process includes a temperature reduction step in the reactor, followed by a temperature maintenance step, and finally, the steam injection is stopped, with only air being introduced into the reaction medium, for example, at a controlled flow rate. To achieve this, for example, the superheater is initially stopped to inject saturated steam (for example, at 100°C) into the reactor and proceed with cooling. Once the reaction medium temperature is reached, the steam injection is stopped, the temperature is maintained, for example, by the action of heating elements in the reactor, and ambient air is introduced into the reactor. For example, the air injection flow rate is regulated based on the O2 concentration at the reactor outlet.Once this rate approaches 20-21%, the post-oxidative treatment stage is complete and, for example, saturated steam is injected again to cool the product.

[0173] According to a second embodiment, 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 maintained to more rapidly renew the reaction volume and thus maintain a stable temperature. For example, ambient air is injected into the reaction medium at 500°C, no longer regulating the output O2 level (for example, since the oxygen has 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 determines the mass of O2 to be injected and therefore the air flow rate to be introduced for what duration.As with the first implementation example, once the reaction is complete, the air injection can be stopped, as well as the heating of the steam, in order to proceed with the cooling of the product using saturated steam.

[0174] According to a third embodiment, the first and second examples are combined; that is, initially, the process includes a cooling step followed by a slow heating step of the reaction medium during the oxidative post-treatment step, for example, to control the air flow rate as well as the reaction temperature of the oxidative post-treatment. However, this embodiment is longer in time and requires more energy.

[0175] These implementation examples are generally carried out directly after the thermolysis or steam-thermolysis reaction (before the temperature drop and the reactor opening). However, they can also be performed on an independent cycle (after complete cooling and a further temperature increase). This, however, then entails an additional energy cost (the temperature must be raised again at the beginning of the second cycle). 4. Treatment of gaseous products

[0176] The gaseous products from vapor-thermolysis are treated by total decomposition using thermal oxidation. This equipment consists of a low-NOx burner, two combustion chambers, and a urea-sprayed SNCR (selective non-catalytic reduction) NOx treatment system.

[0177] The thermolysis gases produced by 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 nitrogen oxide emission limits, an example of a combination of emission control technologies has been implemented with the following elements: • A LowNOx burner that generates little NOx during the oxidation of organic species. • A double oxidation chamber configured to allow total oxidation of organic compounds without oxidizing nitrogen. • Reduction of residual NOx by "non-catalytic reduction" with urea spraying in the gas stream at temperature. The urea flow rate will be oversized relative to the amount of NOx to be treated, thus allowing for maximum reduction.

[0178] The first oxidation chamber is operated at substoichiometric temperature and very high temperature, and to significantly limit the formation of nitrogen oxides, this equipment is fitted with a double jacket. This design cools the metallic structure of the primary oxidation chamber. A spray bar delivering 20 to 50 m³ / h of reverse osmosis water is installed to maintain the temperature of the structure within the permissible limits for the material. The cooling water is collected in the bottom of the double jacket, then pumped to a plate heat exchanger, the primary heat exchanger 127, to be cooled and re-injected into the oxidizer 120 for a new cooling cycle.

[0179] A counter-current flow of glycol water, for example at a flow rate between 30 m3 / h and 60 m3 / h, also passes through the plate heat exchanger 127 to finally remove excess heat by means of a closed-circuit air cooler located outside.

[0180] The gaseous discharge into the atmosphere is cooled by injecting fresh air (for example, between 5000 and 25000 Nm³ / h) at the outlet of the thermal oxidizer 120 in order to limit the temperature in the stack. The temperature is, for example, between 300 and 400°C for a steel stack, for example with a diameter of approximately 900 mm to 1500 mm, which makes it possible, for example, to limit the ejection velocity and / or noise levels.

[0181] The treatment of gaseous effluents consists of open-flame oxidation of all organic species present. Guidelines for this type of treatment recommend that the organic compounds be subjected to a temperature above 850°C for a minimum of 2 seconds.

[0182] The thermal oxidizer 120 according to an example 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 above.

[0183] 5. Unloading, quality control and packaging

[0184] 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 containing the fibers is then weighed using the same scale as during loading to monitor the degradation rate of the organic compound in the composite. The fibers are then removed from the loading trolley and placed in a transfer area.

[0185] A sample of the recycled fibers obtained is taken to perform a quality control check of the thermolysis reaction (absence of residual organic compounds on the recycled fibers). If this preliminary check proves positive, then mechanical quality checks of the rCF are carried out.

[0186] The recycled fibres then undergo the following operations: - Sorting: at the outlet of the vapo-thermolysis reactor, the carbon fibers are separated from other waste (bolts, ...); - Packaging and storage: the sorted rCFs are packaged and then stored in cartons, bags, IBCs or big bags; - Shipping: when ordered, the carbon fiber is packaged in cartons, 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 step of heating the reactor (100) to a first temperature between 300°C and 600°C; - a step of injecting oxygen into the reactor (100) configured to produce an oxygen content 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 - a step of oxidizing the organic compound to carbon monoxide (CO) and / or carbon dioxide (CO2).

2. A method according to claim 1, wherein oxygen is injected into the reactor (100) for a period of between 10 minutes and 6 hours.

3. A process according to any one of claims 1 or 2, wherein the oxidative post-treatment step comprises: - A step of reducing the temperature in the reactor (100), from the first temperature to a second temperature, the second temperature being between 300°C and 500°C; - A step of maintaining the second temperature for a period of between 10 min and 6 hours; and - A step of introducing oxygen into the reactor (100).

4. A method according to claim 3, wherein the oxidative post-treatment step comprises a step of reducing steam injection into the reactor (100).

5. A method according to any one of claims 3 or 4, wherein the oxygen introduction step comprises a step of regulation of the injection flow rate according to an oxygen content at the reactor outlet (100).

6. A method according to any one of claims 3 to 5, 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).

7. A method according to any one of claims 1 to 6, comprising a step of measuring a quantity of oxygen at the outlet of the reactor (100); and if an oxygen content is stable, the method comprises: - A step of stopping the injection of oxygen; and / or - A step of stopping the heating of the steam; and / or - A step of cooling the reactor (100) comprising a step of injecting saturated steam.

8. A processing device configured to carry out a process for processing a composite material according to any one of claims 1 to 7, the device comprising a reactor (100) and a steam superheater (103), upstream of the reactor (100), the steam superheater (103) being configured to raise steam to a temperature between 300°C and 600°C for injection into the reactor (100), the device further comprising a water treatment unit (105) configured to treat tap water and provide reverse osmosis water, a storage unit (109) configured to store the reverse osmosis water and to supply reverse osmosis water to a thermal oxidizer (120) and / or a steam generator (113), the thermal oxidizer (120) configured to treat steam and gaseous products emanating from the reactor, and the steam generator (113) configured to superheat osmosed water and provide saturated steam for the steam superheater (103).

9. Device according to claim 8, 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.

Images