Reactor for dissolving a solid feedstock based on thermosetting materials such as used-tyre granules

Abstract

The invention relates to a reactor for dissolving a solid feedstock in the form of granules having sizes of for example between 1 and 25 mm, such as used-tyre granules, in the presence of an upflow reaction stream comprising a liquid solvent, said reactor comprising a chamber (1) of elongate shape along the vertical axis, comprising an upper portion (210) of cross section S1 and a lower portion (220) of cross section S2, the cross section S1 of the upper portion (210) being greater than the cross section S2 of the lower portion (220), said reactor also comprising a loop for recirculation of the reaction stream, comprising a means (6) for withdrawing at least one fraction of the reaction stream, located at the upper portion (210), and a means (5) for introducing at least one fraction of the withdrawn reaction stream, located at the lower portion (220).

Description

[0001] REACTOR FOR DISSOLVING A SOLID CHARGE BASED ON THERMOSETTING MATERIALS SUCH AS USED TIRE GRANULES

[0002] Technical field

[0003] The present invention relates to the field of dissolution of solid filler based on thermosetting materials such as used tire granules. It also relates to the field of dissolution and conversion of used tires by thermal decomposition.

[0004] State of the art

[0005] Thermal decomposition conversion processes for used tires generally aim to produce gaseous, liquid and solid fractions. The tire is generally initially crushed to obtain either shredded tires still containing a portion of the textile fibers or metal wires contained in the tire (typically pieces of 1 to 10 cm) or aggregates (generally less than 6 mm in size) free of textile fibers or metal wires. It is possible to react these charges thus prepared by exposing them to temperature to decompose the used tire and recover a gaseous fraction, a liquid fraction and a solid fraction. To decompose the tire, it is generally necessary to expose the tire to a fairly high temperature, generally between 300°C and 900°C for reaction times ranging from 30 minutes to several hours.

[0006] There are many technologies for implementing these reactions. For example, tires can be subjected to high temperatures in rotating furnaces (Lewandowski et al., Journal of Analytical and Applied Pyrolysis, 140, 2019, 25-53), or in moving beds (EP2661475). These technologies are robust but generally require working at fairly high temperatures, generally on average above 500°C. In these processes, the carbon black, generally present in the feed at a rate of 25-40% by weight and originally consisting of very fine sub-micrometric or micrometric particles / agglomerates, tends to agglomerate in the presence of the decomposed gum which forms a coke binding these structures at different scales, the solid often leaving the reactor in the form of blocks of several millimeters / centimeters which must then be finely ground in order to reuse this solid as carbon black, which requires a significant energy expenditure.In these processes, the temperature conditions are high and the reactor contains mainly gaseous and solid fractions. The liquids produced then result from the condensation of the gaseous products downstream of the reactor. These high temperature conditions also tend to favor polycondensation and coking reactions to form polyaromatic structures from cyclization reactions involving the aromatic and olefinic structures present (MF Laresgoiti, BM Caballero, I. de Marco, A. Torres, MA Cabrero, MJ Chomôn. J. Anal. Appl. Pyrolysis 71 (2004) 917-934) or coke. The higher the temperature, the greater the contents of polyaromatic structures formed and coke formed.However, while aromatic molecules are good solvents and have many applications, particularly as petrochemical bases, polyaromatic structures are detrimental to the quality of the liquid formed and very difficult to refine or convert. They are also precursors of coke. It is therefore advisable to try to limit polycondensation reactions as much as possible to produce a minimum of polyaromatic structures while preserving the monoaromatic structures present.

[0007] To improve the quality of the solid phase and limit the formation of coke on the carbon black, it is possible to lower the partial pressure of hydrocarbons by injecting steam during the cracking reactions which nevertheless require a high temperature above 500°C to carry out the cracking in essentially gas-solid conditions (LIS2016 / 0083657). These gas-solid processes generally induce production of incondensable gases in atmospheric conditions which are very high and between 10 and 25% by weight relative to the tire charge entering the reactor. However, the recovery of reaction gases is locally complex. These gases are therefore generally used to produce the heat required to carry out the reactions but this is to the detriment of the quantity of easily recoverable liquid products which is therefore then limited.These liquid fractions are then eventually reused to produce new hydrocarbon fractions (naphtha, gasoline, kerosene, diesel, vacuum distillate, residues) used in refineries to produce fuels or in petrochemicals to produce bases then used to make plastics. However, these fractions must be refined to meet the desired specifications. The more polyaromatic structures there are, the more complex the refining process.

[0008] An alternative method consists of bringing the tire fillers into contact with a liquid, raising the temperature of this liquid and dissolving and converting the tires into a homogeneous liquid phase in which the tire filler is agitated and gradually disappears. An example of this implementation is given in US 3,978,199 and US 3,704,108. This type of process makes it possible to recover the carbon black in the liquid phase after filtration without there being agglomeration of these particles or deposition of coke on their surface as is the case in reactions operating in the gas-solid phase. Implementation under temperature conditions below 450°C also limits the polycondensation reactions of the aromatics, the formation of coke on the surface of the carbon black particles and the formation of gas which is generally between 1 and 7% by weight of the re-entrant filler.The use of a solvent containing aromatic fractions, preferably monoaromatic, is favorable and allows better dissolution of the feedstock in the reactor. As tires are naturally composed of different rubbers including significant quantities of synthetic rubber composed of styrene-butadiene rubber (SBR or "Styrene Butadiene Rubber" according to English terminology), the liquid fractions produced contain significant aromatic fractions and it may be advantageous to separate and recycle part of the liquid formed during the reaction to use it as a solvent, while the non-recycled liquid fraction can be sent to a refinery to be refined and then recovered as a hydrocarbon cut to feed the product pools or petrochemicals.

[0009] More specifically, the process described in US patent 3,704,108 comprises a fluidized bed reactor fed with a feedstock composed of tire granules on the one hand, and the solvent on the other. The reaction is carried out in the presence of hydrogen and a catalyst under more severe temperature conditions of between 370°C and 450°C. No initial step promoting the dissolution of the tires is described in this process. However, it is specified that the formation of a transportable slurry composed of aggregates and solvents that can be transported and heated upstream of the reactor requires the use of finely divided tire particles of between 150 and 3000 μm.

[0010] The process described in US patent 3,978,199 comprises a contact reactor between the tires and the solvent allowing the dissolution of the tires in the solvent and the recovery of the carbon black, this reactor being characterized by the fact that it is perfectly stirred using mechanical mixing means, and which operates at a temperature between 260°C and 370°C. The use of a perfectly stirred reactor requires having large quantities of liquid because the rubber tends to soak up liquid and swell. In addition, it is also necessary to fill the intergranular space between the tire granules to stir the suspension consisting of the granules and the solvent. Thus, the examples illustrate a solvent / tires ratio close to 5 weight / weight.Furthermore, the process described only consists of dissolving the tire rubber at a moderate temperature below 370°C which does not allow for efficient and significant conversion of the liquid resulting from the dissolution of the rubber.

[0011] Application FR3108617 discloses a process sequence for converting used tires and plastics in which a solid charge based on crushed used tires in the form of aggregates of 5 mm or less is sent to a reaction zone in the presence of a liquid solvent comprising aromatic compounds to at least partially dissolve said solid charge and thermally decompose said at least partially dissolved solid charge at a temperature less than or equal to 425°C in order to obtain carbon black and a first liquid hydrocarbon fraction. The dissolution of the used tires can be carried out in a first reactor mechanically stirred or hydrodynamically stirred by an upward flow of liquid. However, the dissolution reactor described does not include means for separating the undissolved aggregates which can be entrained with the liquid at the outlet of the dissolution reactor.Indeed, as the reactor is perfectly agitated, some of the undissolved aggregates can be carried away in the liquid leaving the dissolution reactor. To minimize this quantity of partially or slightly dissolved aggregates at the outlet of the dissolution reactor, it is preferable to use relatively small aggregates (<5mm) to have a very rapid dissolution of the aggregates which makes it possible to limit the entrainment of aggregates downstream in the liquid products.

[0012] The literature review shows that the initial dissolution stage of used aggregates is important for converting used tires into liquid products and recovering carbon black. Advances in tire shredding and granulation techniques now make it possible to produce tire aggregates in the range of 15 to 25 mm in size, free of more than 95% textile or metal fibers. The ability to recover large-sized aggregates is advantageous because it reduces the energy and costs required to produce these aggregates. However, as the size of the aggregates increases, the transportation and dissolution problems become more significant.An object of the present invention is to propose a dissolution reactor, also called here solubilizer, of a solid load based on thermosetting materials such as used tire granules making it possible to treat granules of any size, therefore with current technologies for obtaining granules whose size can for example be up to 25 mm.

[0013] Objects of the invention

[0014] A first object according to the invention relates to a Reactor for dissolving a solid charge based on thermosetting materials in the form of aggregates of sizes between a 1 ère minimum value and a 2 nde maximum value, such as used tire granules, in the presence of an updraft reaction flow comprising a liquid solvent, said solvent being capable of dissolving said solid charge, said reactor comprising:

[0015] - an enclosure of elongated shape along the vertical axis, said enclosure comprising an upper part of cross section S1 and a lower part of cross section S2, the upper part being located above the lower part along the vertical axis; - a means for introducing the solid charge located in the upper part of the enclosure;

[0016] - a means of introducing the liquid solvent;

[0017] - a means for discharging at least a fraction of the reaction flow outside said dissolution reactor;

[0018] - a means for purging a gaseous fraction located at the top of the reactor enclosure, said reactor being characterized in that:

[0019] - the cross-section S1 of the upper part of the enclosure is greater than the cross-section S2 of the lower part of the enclosure; and in that

[0020] - said reactor further comprises a recirculation loop for the reaction flow comprising a means for withdrawing at least a fraction of the reaction flow located at the upper part of the enclosure and a means for introducing at least a fraction of the withdrawn reaction flow located at the lower part of the enclosure.

[0021] According to one or more embodiments, the upper part and the lower part have a substantially circular section, and in that the ratio between the diameter of the cross section S2 and the diameter of the cross section S1 is between 0.1 and 0.8.

[0022] According to one or more embodiments, the upper portion of the enclosure and the lower portion of the enclosure are connected by a frustoconical element flaring upwards along the vertical axis.

[0023] According to one or more embodiments, the half-angle formed by the cross-section of said frustoconical element with the vertical axis is between 7° and 45°.

[0024] According to one or more embodiments, the means for evacuating at least a fraction of the reaction flow is located in the recirculation loop between said withdrawal means and said introduction means.

[0025] According to one or more embodiments, said means for introducing the solid charge is located at the top of the reactor enclosure.

[0026] According to one or more embodiments, the means for withdrawing at least a fraction of the reaction flow is located axially in the center of the cross section of the upper part overhung by a deflector.

[0027] According to one or more embodiments, the means for introducing the solid charge is located at the periphery of the upper part of the reactor enclosure. According to one or more embodiments, the reactor further comprises at least one grid arranged along the vertical axis in the upper part of the reactor enclosure, between the wall of the reactor enclosure and the means for withdrawing the reaction flow, and in that the lower part of said grid is located at a lower height than the inlet of the withdrawal means.

[0028] According to one or more embodiments, the means for introducing the liquid solvent is located either in the lower part of the enclosure or directly in the recirculation loop of the reaction flow.

[0029] Another object according to the invention relates to a continuous process for dissolving a solid charge based on thermosetting materials in the form of sizes between a 1 ère minimum value and a 2 nde maximum value in the presence of a reaction flow containing a liquid solvent circulating in an ascending current in a reactor according to the invention, operating at a temperature between 150°C and 350°C, said process comprising at least the following steps:

[0030] - the liquid solvent is introduced into the reactor enclosure so as to completely immerse the lower part of said enclosure and partially immerse the upper part of said enclosure, forming a gaseous canopy above the reaction flow;

[0031] - the solid charge is introduced into the upper part of the reactor enclosure;

[0032] - a fraction of the reaction flow located in the upper part of the enclosure is withdrawn;

[0033] - at least part of the withdrawn reaction flow is evacuated outside of said process;

[0034] - at least part of the reaction flow drawn off in the lower part of the enclosure is recycled; in which the surface velocity of the reaction flow in the upper part is fixed at a value lower than the terminal fall velocity calculated for aggregates having a size equal to 1 ère minimum value and the surface velocity of the reaction flow in the lower part is set to a value greater than the minimum fluidization velocity calculated for aggregates having a size equal to 1 ère minimum value, given that the surface speeds in the upper and lower parts are different.

[0035] According to one or more embodiments, the minimum value is equal to 1 mm and the maximum value is equal to 25 mm.

[0036] According to one or more embodiments, the superficial velocity of the reaction flow in the upper portion (210) is less than 1 cm / s. According to one or more embodiments, the superficial velocity of the reaction flow in the lower portion (220) is between 2 and 15 cm / s.

[0037] According to one or more embodiments, the residence time of the solid charge in the lower part of the reactor enclosure is between 15 minutes and 20 hours.

[0038] According to one or more embodiments, the solid charge is introduced into the gaseous air space located in the upper part of the enclosure.

[0039] According to one or more embodiments, the mass ratio between the liquid solvent and the solid filler is less than 2.5 weight / weight.

[0040] According to one or more embodiments, the solid filler is a filler based on used tire granules.

[0041] List of figures

[0042] Figure 1 is a schematic representation of the reactor according to the invention.

[0043] Figure 2 is a schematic representation of the reactor according to an embodiment according to the invention.

[0044] Figure 3 is a schematic representation of the reactor according to another embodiment according to the invention.

[0045] Figure 4 is a schematic representation of an implementation of the reactor according to the invention in a process for the solvolysis of a load based on used tires.

[0046] Detailed description

[0047] Definitions

[0048] In this description, the term “Cx hydrocarbons” designates hydrocarbon compounds containing x carbon atoms. The term “Cx+ hydrocarbons” designates hydrocarbon compounds containing at least x carbon atoms. The term “Cx to Cy hydrocarbons” designates hydrocarbon compounds containing between x and y carbon atoms.

[0049] The terminal falling velocity (Vt) of a particle can be defined according to the following mathematical formula: Vt=£2.G.Vp.tafi -œW(GtMÛD)) A 0.5 with G= 9.81 m / s 2 ,

[0050] Vp: volume of the particle (m 3 ), rop: density of the particle in the fluid (kg / m 3 ), rof: fluid density (kg / m 3 ),

[0051] Cd: drag coefficient calculated as a function of the Reynold number (dimensionless), Ap: cross-sectional area projected by the particle in a plane perpendicular to the flow (m 2 ).

[0052] The fluidization velocity is a parameter well known to those skilled in the art, and can for example be calculated via the correlation indicated in the work of Wen CH & Yu YH, Chemical engineering progress symposium series, 82, 100-111 (1966).

[0053] The size of the aggregates is defined by their equivalent diameter dsv corresponding to a spherical particle which would have the same surface / volume ratio.

[0054] Detailed description

[0055] Figure 1 relates to a reactor for dissolving a solid charge based on thermosetting materials of size for example between 1 and 25 mm such as used tire granules in the presence of an upward-flowing reaction flow comprising a liquid solvent, said solvent being capable of dissolving said solid charge, said reactor comprising:

[0056] - an enclosure 1 of elongated shape along the vertical axis comprising an upper part 210 of cross section S1 and a lower part 220 of cross section S2, the upper part 210 being located above the lower part 220 along the vertical axis, and the cross section S1 of the upper part 210 of the enclosure 1 is greater than the cross section S2 of the lower part 220 of the enclosure 1;

[0057] - a means 2 for introducing the solid charge located in the upper part 210 of the enclosure 1;

[0058] - a means 4 for introducing the liquid solvent;

[0059] - a recirculation loop of the reaction flow comprising a means 6 for withdrawing at least a fraction of the reaction flow located at the level of the upper part 210 of the enclosure 1 and a means 5 for introducing at least a fraction of the withdrawn reaction flow located at the level of the lower part 220 of the enclosure 1;

[0060] - a means 7 for discharging at least a fraction of the reaction flow outside said dissolution reactor, preferably located in the recirculation loop between said means 6 for withdrawing at least a fraction of the reaction flow and said means 5 for introducing at least a fraction of the withdrawn reaction flow;

[0061] - a means 3 for purging a gaseous fraction located at the top of the reactor enclosure 1.

[0062] According to an essential aspect of the reactor according to the invention, the cross-section S1 of the upper part 210 of the enclosure 1 is greater than the cross-section S2 of the lower part 220 of the enclosure 1. Preferably, the upper part 210 and the lower part 220 have a substantially circular section, and the ratio between the diameter of the cross-section S2 and the diameter of the cross-section S1 is between 0.1 and 0.8, preferably between 0.3 and 0.7. The difference in cross-section size between the upper part and the lower part of the reactor enclosure makes it possible to create, during operation of the reactor, a difference in the surface velocity of the reaction flow circulating in an upward current in the enclosure of said reactor depending on whether the reaction flow is located in the upper part or in the lower part of the reactor enclosure.When implementing the reactor in a solid charge dissolution process, the lower part 220 of the reactor enclosure, which may be called the fluidized bed zone, comprises undissolved or partially dissolved solid charge aggregates but larger than 1 mm in size which are maintained in the fluidized state by the reaction flow. The upper part 210 of the reactor enclosure, which may be called the disengagement zone or separation zone, comprises aggregates smaller than 1 mm in size resulting from the dissolution of the aggregates, and aggregates larger than 1 mm in size which will sediment and flow towards the lower part of the reactor enclosure. Thus, due to the structure of the reactor according to the invention, the reaction flow withdrawn via the withdrawal means only contains solid charge aggregates smaller than 1 mm in size and which are therefore easily transportable or pumpable.This dissolution reactor can thus be coupled to a reaction zone making it possible to convert part of the reaction flow withdrawn under operating conditions more severe than those used during the dissolution of the solid load, making it possible to thermally decompose the aggregates of the solid load of a size less than 1 mm and to obtain, when the solid load used is based on used tires, carbon black and a liquid fraction comprising hydrocarbon compounds which can then be recovered.

[0063] The liquid solvent makes it possible to dissolve at least in part the solid charge. The liquid solvent is preferably a hydrocarbon fraction advantageously comprising between 15% and 80% by weight of aromatic compounds relative to the total weight of the solvent. Preferably, the liquid solvent comprises less than 10% by weight of hydrocarbon compounds whose boiling point is less than 250°C and less than 10% by weight of hydrocarbon compounds whose boiling point is greater than 520°C relative to the total weight of the liquid solvent. Preferably, the liquid solvent comprises at least 90% by weight of hydrocarbon compounds whose boiling point is between 300°C and 500°C. The liquid solvent may be entirely or at least partly composed of an external solvent. For example, the liquid solvent may be at least partly derived from a heavy distillate fraction (HCO or "heavy cycle oil" according to English terminology).

[0064] The liquid solvent may be composed at least in part of a fraction of the reaction flow withdrawn in the upper part 210 and recycled in the lower part 220 of the reactor enclosure via the recirculation loop.

[0065] In the embodiment illustrated in Figure 1, the liquid solvent is supplied via an introduction means 4 located in the lower part 220 of the enclosure 1 of the reactor. In the embodiments illustrated in Figures 2 and 3, the solvent is supplied into the recirculation loop of the reaction flow via the introduction means 4. The solvent is injected into the reactor via the introduction means 5 of at least a fraction of the withdrawn reaction flow. In the embodiment according to Figure 3, the introduction means 4 is located upstream of a heat exchanger 280 located in the recirculation loop making it possible to heat the withdrawn reaction flow and therefore also to heat the supplied liquid solvent before its introduction into the reactor.

[0066] The reactor according to the invention comprises a means 2 for introducing the solid charge located in the upper part 210 of the enclosure 1 of the reactor.

[0067] In an embodiment according to the invention, as illustrated in Figure 2, the means 2 for introducing the solid feedstock is located at the top of the enclosure 1 of the reactor. The solid feedstock can thus be fed into the reactor through a system of valves making it possible to control the flow rate of the solid feedstock entering the reactor. In the embodiment of Figure 2, the reactor further comprises a deflector 230 located above the means 6 for withdrawing the fraction of the reaction flow, thus making it possible to divert the flow of solid feedstock entering the reactor via the introduction means 2.

[0068] In another embodiment according to the invention, as illustrated in Figure 3, the means 2 for introducing the solid feed is located at the periphery of the upper part 210 of the enclosure 1 of the reactor. The solid feed is thus fed into the reactor through a screw-feeder system making it possible to control the flow rate of the solid feed entering the reactor. In this embodiment, the reactor may comprise at least one grid 250, preferably a plurality of grids, arranged along the vertical axis in the upper part 210 of the enclosure 1 of the reactor, between the wall of the enclosure 1 of the reactor and the means 6 for withdrawing the reaction flow. Advantageously, the lower part of said grid 250 is located at a lower height than the inlet of the withdrawal means 6.The grid 250 makes it possible to contain the solid charge entering the reactor and to avoid being directly withdrawn by the withdrawal means 6 of a fraction of the reaction flow.

[0069] The recirculation loop of the reaction flow of the reactor according to the invention comprises the means 6 for withdrawing a fraction of the reaction flow located at the upper part 210 of the enclosure 1 and the means 5 for introducing at least a fraction of the withdrawn reaction flow located at the lower part 220 of the enclosure 1. The withdrawal means 6 makes it possible to withdraw a portion of the reaction flow containing the liquid solvent and a liquid phase resulting from the dissolution of the solid charge in the reactor, as well as a fraction of the at least partially dissolved solid charge, entrained by the ascending current of the reaction flow. When implementing the reactor in the process of dissolving the solid charge, the withdrawal means 6 must be positioned in the upper part 210 of the enclosure 1 of the reactor and below the gas-liquid interface 240.Preferably, the withdrawal means 6 is located axially in the center of the cross-section of the upper part 210 of the enclosure 1 of the reactor. At least a fraction of the withdrawn reaction flow is recycled into the lower part 220 of the enclosure 1 of the reactor via the introduction means 5, which makes it possible to limit the quantity of solvent to be introduced into the reactor to achieve a reaction flow rate making it possible to fluidize the largest aggregates of the solid charge in the lower part 220 of the reactor.

[0070] According to an embodiment according to the invention, as illustrated in Figures 2 and 3, the upper part 210 of the enclosure 1 and the lower part 220 of the enclosure 1 are connected by a frustoconical element 260 widening upwards along the vertical axis. Preferably, the half-angle formed by the cross-section of said frustoconical element 260 with the vertical axis is between 7° and 45°, preferably between 10° and 30°.

[0071] The reactor according to the invention can thus be implemented in a process allowing the dissolution of a solid charge based on thermosetting materials, preferably used tire granules, of sizes between a 1 ère minimum value and a 2 ndmaximum value, for example between 1 and 25 mm, in the presence of a liquid solvent capable of dissolving said solid charge. The process is advantageously carried out at a temperature between 150°C and 350°C, if it is desired to minimize the conversion of the hydrocarbon compounds present in the reaction flow during the dissolution step. Preferably, the process is carried out at a temperature between 200°C and 320°C, and even more preferably at a temperature between 250°C and 320°C. The process according to the invention comprises at least the following steps: - the liquid solvent is introduced into the enclosure 1 of the reactor so as to completely immerse the lower part 220 of said enclosure 1 and to partially immerse the upper part 210 of said enclosure 1 forming a gaseous canopy overlying the reaction flow;

[0072] - the solid charge is introduced into the upper part 210 of the reactor enclosure 1;

[0073] - a fraction of the reaction flow located in the upper part 210 of the enclosure 1 is withdrawn;

[0074] - at least part of the withdrawn reaction flow is evacuated outside of said process;

[0075] - at least part of the reaction flow drawn off in the lower part 220 of the enclosure 1 is recycled; in which the surface velocity of the reaction flow in the upper part 210 is fixed at a value lower than the terminal fall velocity calculated for aggregates having a size equal to 1 ère minimum value and the surface velocity of the reaction flow in the lower part 220 is set to a value greater than the minimum fluidization velocity calculated for aggregates having a size equal to 1 ère minimum value, given that the surface speeds in the upper and lower parts are different.

[0076] As described above, the difference in cross-sectional size between the upper part and the lower part of the reactor enclosure makes it possible to create, during operation of the reactor, a difference in the surface velocity of the reaction flow circulating in an upward current in the enclosure of said reactor depending on whether the reaction flow is in the upper part or in the lower part of the reactor enclosure.

[0077] The surface velocity of the reaction flow in the lower portion 220 must be greater than the minimum fluidization velocity of the largest used tire aggregates included in said reaction flow. The minimum fluidization velocity is a characteristic which is well known to those skilled in the art and which depends on the size of the aggregates, the density of the aggregates in the reaction flow, the density of the liquid and the viscosity of the liquid contained in the reaction flow. For example, for tire aggregates of 20 mm diameter, the minimum fluidization velocity generally varies between 1 and 15 cm / s, preferably between 3 and 10 cm / s.If the size of the aggregates decreases, the minimum fluidization speed decreases, so the speed of the reaction flow in the lower part of the reactor enclosure must be higher than the minimum fluidization speed of the largest aggregates in order to ensure that the aggregates are well mixed under the effect of fluidization. Consequently, the surface speed of the reaction flow located in the lower part 220 is advantageously between 2 and 15 cm / s, and more preferably between 5 and 10 cm / s. The surface speed of the reaction flow in the upper part 210 must be lower than the terminal fall speed of the largest aggregates which can thus be entrained in the reaction flow. The terminal fall speed characterizes the minimum speed to which an aggregate can be subjected to entrain it in a vertical flow.This characteristic is well known to those skilled in the art and depends on the size of the aggregates, the density of the aggregates in the liquid flow, the density of the liquid and the viscosity of the liquid contained in the reaction flow. For example, for 1 mm tire aggregates, the terminal fall velocity in the reaction flow is generally greater than 1 cm / s. In order to avoid the entrainment of particles larger than 1 mm, the upper part 210 is advantageously sized so that the surface velocity of the reaction flow in the upper part is less than 1 cm / s, preferably less than 0.5 cm / s.

[0078] Preferably, the solid feedstock is introduced into the gaseous headspace located in the upper part 210 of the reactor enclosure 1. Thus, the solid feedstock flows by gravity into the gaseous phase before entering the liquid phase comprising the reaction flow. Advantageously, an inert gas may be introduced into the reactor enclosure with the solid feedstock to avoid any convection heating of the solid feedstock supplied via the introduction means 2 and which also facilitates the flow of the solid feedstock into said introduction means. A purge means 3, located at the top of the reactor enclosure, allows the evacuation of an adequate quantity of gaseous fraction.

[0079] When implementing the method according to the invention, a fraction of the reaction flow located in the upper part 210 of the enclosure 1 is withdrawn. The withdrawal is carried out via a withdrawal means 6 which allows the exit of at least a fraction of the reaction flow containing the liquid solvent, the liquid resulting from the dissolution of the solid charge, as well as a portion of the solid charge whose size is preferably less than 1 mm. At least a portion of the withdrawn reaction flow is removed from the process via a discharge means 7 located in the recirculation loop, the other portion of the reaction flow is recycled into the lower part 220 of the enclosure 1 of the reactor via the introduction means 5. Advantageously, the withdrawn reaction flow is heated via a heat exchanger 280 before being reintroduced into the enclosure of the reactor.Advantageously, a liquid solvent supplement may be introduced into the circulation loop via the introduction means 4 to be mixed with the withdrawn reaction flow before being sent into the reactor enclosure (see Figures 2 and 3). Preferably, the introduction means 4 of the liquid solvent is located upstream of the heat exchanger 280. Preferably, the residence time of the solid charge in the lower part 220 of the reactor enclosure is between 15 minutes and 20 hours, preferably between 15 minutes and 3 hours, to allow the solubilization of the aggregates of the solid charge.

[0080] Preferably, the volume fraction occupied by the solid charge in the lower part 220 of the enclosure 1 of the reactor is between 10% and 50% by volume, preferably between 15% and 30% by volume, so as to be sufficiently low to avoid any risk of clogging of the reactor by accumulation of the aggregates of the solid charge.

[0081] It is possible to adjust the vacuum ratio by modifying the superficial velocity of the liquid in section S2 of the lower part 220 of the enclosure 1.

[0082] The use of a portion of the recycled reaction flow as liquid solvent makes it possible to make the use of a very limited quantity of external solvent. Indeed, the minimum quantity of solvent necessary to operate a dissolution system without recycling of the reaction flow in relation to the quantity of solid filler granules to be dissolved is greater than 3 weight / weight, or even between 4 and 5 weight / weight to be able to dissolve the solid filler without risk of clogging or fouling of the reactor. In the context of the process according to the present invention, the mass ratio between the liquid solvent and the solid filler is less than 2.5 weight / weight, preferably less than 2 weight / weight.

[0083] Figure 4 illustrates a possible implementation of the reactor according to the invention in a process for solvolysis of a solid feedstock in the form of used tire granulates. The granulates to be recycled 1a are stored in a silo 100 before being introduced into the dissolution reactor according to the invention 200 via the introduction means 2 in which they are brought into contact with a hydrocarbon fraction via the line 4a as a liquid solvent which is produced here in situ thanks to the separation of the products of the solvolysis process. Depending on the operating pressure of the dissolution reactor, it is possible to have other silos upstream of the silo 100 between which the granulates to be recycled circulate in a cycle, which makes it possible to ensure the pressurization of the last silo feeding the reactor.The dissolution step is carried out at a temperature between 150°C and 350°C to minimize the conversion of the liquid hydrocarbon fractions present and the pressure is adjusted to minimize the vaporization of the hydrocarbons. It is also possible to use at least partially an external solvent as previously described. A portion of the reaction stream is withdrawn via line 6a resulting from the dissolution of the aggregates in the solubilizer and containing only particles whose size is less than 1 mm, residues from the dissolution step.A portion of the withdrawn reaction stream is recycled into the dissolution reactor according to the invention 200 via line 5a, and the other portion of the withdrawn reaction stream is discharged from the dissolution reactor via line 7a to be directed to a conversion reactor 300 operating at a temperature between 350°C and 420°C, preferably between 380°C and 400°C in order to promote the thermal cracking reactions of the hydrocarbons allowing their conversion, without however producing too many very light gaseous fractions. The pressure in this reactor is controlled to maintain a majority of the hydrocarbons in liquid form, typically more than 50% by weight of the incoming feedstock, preferably more than 80% by weight of the incoming feedstock to the reactor 300. The gaseous effluent obtained 8 is then cooled in a condensation and separation zone 400 to obtain a liquid effluent 18 and an effluent of incondensable fractions 17.The liquid fraction 9 leaving the reactor 300 contains the carbon black initially contained in the aggregates of the initial solid charge, which under the effect of dissolution and thermal cracking reactions is completely released. The carbon black is essentially made up of very fine particles, individual or agglomerated on a micron or submicron scale and whose size does not exceed 50-100 μm. The liquid fraction 9 is sent to a filtration zone 500 making it possible to separate these particles and to produce a filtrate 10 free of particles and a cake still soaked in hydrocarbon compounds 21 which is then sent to a washing zone 700 in the presence of a light external solvent 22, 23, such as acetone, toluene or xylene. The solvent and the hydrocarbon compounds are separated in a separation zone 800, for example by distillation.After the separation step, the solvent can be recycled upstream of the washing zone via line 24, and the recovered hydrocarbon compounds can be sent together with the filtrate via line 11 to a distillation zone 600 to produce hydrocarbon cuts 12, 14 comprising boiling temperatures set by the operator. The solvent used in the solubilization reactor according to the invention 200 can be composed of a portion of the liquid fractions 20 leaving at the top of the reactor 300 or of a portion of the liquid fractions recovered at the bottom of the reactor 300 after filtration 500, i.e. fractions 13 and 16. The remaining fractions 19, 27, and 15 can be recovered in other external processes.

[0084] Examples

[0085] The following examples are intended to demonstrate the advantages of a reactor according to the invention by comparing the sizing of such a reactor with an installation using two perfectly stirred reactors operating sequentially in closed mode ("batch" according to English terminology). Example 1: Reactor according to the invention

[0086] A dissolution reactor is considered for treating used tire granules with a capacity of 15 kt per year. The granules have a size between 10 and 15 mm. The reactor according to the invention is that described in Figure 3.

[0087] The dissolution reactor according to the invention has the following structural characteristics:

[0088] - diameter of the lower part 220 = 1.44 m

[0089] - height of the lower part 220 = 5.76 m

[0090] - diameter of the upper part 210 = 2.88 m

[0091] - liquid height in the upper part 210 = 3 m

[0092] - deflector height 230 = 1.98 m

[0093] The total volume of the dissolution reaction zone occupied by the reaction flow is 36.4 m 3 .

[0094] For a solvent ratio of 2.5 (defined as the ratio between the solvent flow rate and the tire granule flow rate), the incoming tire flow rate is 1.875 t / h (8000h / year) and the solvent flow rate is 4.688 t / h. The recycled reaction flow rate supplied at the base of the lower part is approximately 200 t / h thanks to the recirculation of part of the dissolved products. Under these conditions, the withdrawn reaction flow is composed of a liquid phase whose viscosity at 100°C is approximately 13 cSt and whose particle concentration (carbon black and partially dissolved tire granules with a size less than 1 mm) is of the order of 10% by volume.

[0095] For a higher solvent rate of 5.5 (ratio between the solvent flow rate and the tire granulate flow rate), the incoming tire flow rate is 1.875 t / h (8000h / year) and the solvent flow rate is 9.375 t / h. The recycled reaction flow rate supplied at the base of the lower part is approximately 200 t / h thanks to the recirculation of part of the dissolved products. Under these conditions, the withdrawn reaction flow is composed of a liquid phase whose viscosity at 100°C is approximately 9 cSt and whose particle concentration (carbon black and partially dissolved tire granulate whose size is less than 1 mm) is of the order of 5.8% by volume.

[0096] Thus, the dissolution reactor in accordance with the invention makes it possible to operate with very variable solvent levels and this makes it possible to adjust the quality of the withdrawn reaction flow comprising the products of interest (carbon black). Example 2: Installation not in accordance with the invention

[0097] The same example was carried out by sizing a unit to dissolve the same quantity of used tire granules in perfectly stirred reactors. Since the effluents from a perfectly stirred reactor have the properties of the container in the perfectly stirred reactor, the granules contained in the perfectly stirred reactor must be exposed to a sufficient reaction time for them to be sufficiently dissolved. Therefore, the perfectly stirred reactor must be operated in closed mode and to ensure equivalent continuous operation, two reactors must be operated in parallel: the first reactor is in unloading / loading operation while the second reactor operates in dissolution, then vice versa.

[0098] For such an installation, the minimum cycle time to ensure wetting of the aggregates, temperature rise and dissolution is at least 3 hours. In addition, taking into account the swelling of the aggregates and the interstitial space between the aggregates, the minimum quantity of solvent to immerse all the aggregates and allow their mechanical agitation is at least 5 times the volume quantity of aggregates.

[0099] It is then necessary to process 5.6251 of aggregates in each reactor, i.e. a volume of 5.625 m 3 for each reactor. The volume of solvent required is therefore 28.1 m 3 and the reaction zone comprises a minimum volume of 33.75 m 3 in each reactor. Finally, with 2 reactors, the minimum total volume is 67.5 m 3or approximately twice the volume of the reaction flow in the dissolution reactor according to the invention. Under these conditions, the reaction flow withdrawn is composed of a liquid whose viscosity at 100°C is approximately 9 cSt and whose particle concentration (carbon black and partially dissolved tire granules whose size is less than 1 mm) is of the order of 5.8% by volume, which is identical to the properties of the reactor according to the invention operating with a solvent rate of 5 weight / weight. But the perfectly stirred reactor does not provide the possibility of reducing the solvent rate, unlike the reactor according to the invention. Indeed, if the solvent rate is reduced in the perfectly stirred reactor, some of the granules will no longer be in contact with the solvent, which will significantly reduce the performance of the dissolution process.

Claims

CLAIMS 1. Reactor for dissolving a solid charge based on thermosetting materials in the form of aggregates of sizes between 1 ère minimum value and a 2 nde maximum value, such as used tire granules, in the presence of an updraft reaction flow comprising a liquid solvent, said solvent being capable of dissolving said solid charge, said reactor comprising: - an enclosure (1) of elongated shape along the vertical axis, said enclosure (1) comprising an upper part (210) of cross section S1 and a lower part (220) of cross section S2, the upper part (210) being located above the lower part (220) along the vertical axis; - a means of introducing (2) the solid charge located in the upper part (210) of the enclosure (1); - a means of introducing (4) the liquid solvent; - a means (7) for discharging at least a fraction of the reaction flow outside said dissolution reactor; - a means (3) for purging a gaseous fraction located at the top of the reactor enclosure (1), said reactor being characterized in that: - the cross-section S1 of the upper part (210) of the enclosure (1) is greater than the cross-section S2 of the lower part (220) of the enclosure (1); and in that - said reactor further comprises a recirculation loop for the reaction flow comprising a means (6) for withdrawing at least a fraction of the reaction flow located at the upper part (210) of the enclosure (1) and a means (5) for introducing at least a fraction of the withdrawn reaction flow located at the lower part (220) of the enclosure (1).

2. Reactor according to claim 1, characterized in that the upper part (210) and the lower part (220) have a substantially circular section, and in that the ratio between the diameter of the cross section S2 and the diameter of the cross section S1 is between 0.1 and 0.

8.

3. Reactor according to one of claims 1 or 2, characterized in that the upper part (210) of the enclosure (1) and the lower part (220) of the enclosure (1) are connected by a frustoconical element (260) widening upwards along the vertical axis.

4. Reactor according to claim 3, characterized in that the half-angle formed by the cross-section of said frustoconical element (260) with the vertical axis is between 7° and 45°.

5. Reactor according to any one of the preceding claims, characterized in that the means (7) for discharging at least a fraction of the reaction flow is located in the recirculation loop between said withdrawal means (6) and said introduction means (5).

6. Reactor according to any one of the preceding claims, characterized in that said means (2) for introducing the solid charge is located at the top of the enclosure (1) of the reactor.

7. Reactor according to claim 6, characterized in that the means (6) for withdrawing at least a fraction of the reaction flow is located axially in the center of the cross section of the upper part (210) overhung by a deflector (230).

8. Reactor according to any one of claims 1 to 5, characterized in that the means (2) for introducing the solid charge is located on the periphery of the upper part (210) of the enclosure (1) of the reactor.

9. Reactor according to claim 8, characterized in that it further comprises at least one grid (250) arranged along the vertical axis in the upper part (210) of the enclosure (1) of the reactor, between the wall of the enclosure (1) of the reactor and the means (6) for withdrawing the reaction flow, and in that the lower part of said grid (250) is located at a lower height than the inlet of the withdrawal means (6).

10. Reactor according to any one of claims 1 to 9, characterized in that the means (4) for introducing the liquid solvent is located either in the lower part (220) of the enclosure (1) or directly in the recirculation loop of the reaction flow.

11. Continuous process for dissolving a solid charge based on thermosetting materials in the form of aggregates of sizes between 1 ère minimum value and a 2 ndemaximum value in the presence of a reaction flow containing a liquid solvent circulating in an ascending current in a reactor according to any one of claims 1 to 10, operating at a temperature between 150°C and 350°C, said process comprising at least the following steps: - the liquid solvent is introduced into the enclosure (1) of the reactor so as to completely immerse the lower part (220) of said enclosure (1) and to partially immerse the upper part (210) of said enclosure (1) by forming a gaseous sky above the reaction flow; - the solid charge is introduced into the upper part (210) of the reactor enclosure (1); - a fraction of the reaction flow located in the upper part (210) of the enclosure (1) is withdrawn; - at least part of the withdrawn reaction flow is evacuated outside of said process; - at least part of the reaction flow drawn off in the lower part (220) of the enclosure (1) is recycled; in which the surface velocity of the reaction flow in the upper part (210) is fixed at a value lower than the terminal fall velocity calculated for aggregates having a size equal to 1 ère minimum value and the surface velocity of the reaction flow in the lower part (220) is set to a value greater than the minimum fluidization velocity calculated for aggregates having a size equal to 1 ère minimum value, given that the surface speeds in the upper and lower parts are different.

12. The method of claim 11, wherein the minimum value is 1 mm and the maximum value is 25 mm.

13. Method according to one of claims 11 or 12, in which the superficial velocity of the reaction flow in the upper part (210) is less than 1 cm / s.

14. Method according to any one of claims 11 to 13, in which the superficial velocity of the reaction flow in the lower part (220) is between 2 and 15 cm / s.

15. Method according to any one of claims 11 to 14, in which the residence time of the solid charge in the lower part (220) of the reactor enclosure is between 15 minutes and 20 hours.

16. Method according to any one of claims 11 to 15, in which the solid charge is introduced into the gaseous air space located in the upper part (210) of the enclosure (1).

17. Method according to any one of claims 11 to 16, in which the mass ratio between the liquid solvent and the solid filler is less than 2.5 weight / weight.

18. Method according to any one of claims 11 to 17, characterized in that the solid filler is a filler based on used tire granules.

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