Fluidised catalytic cracking unit comprising an electrolyser

Abstract

The invention relates to a fluidised catalytic cracking unit comprising: - a reactor (1); - at least one catalyst regenerator (4) designed to feed the reactor with catalyst (3) and to be fed with spent catalyst (7) by the reactor; and - a solid oxide electrolyser (100) capable of producing dioxygen (11) and dihydrogen (12) from a stream comprising in particular water vapour (V1), the solid oxide electrolyser comprising a first outlet for discharging dioxygen and a second outlet for discharging dihydrogen, the first outlet being connected to the catalyst regenerator by means of a feed line for feeding the regenerator, to feed an inlet (41) of the regenerator with dioxygen. The unit comprises a facility (110) for treating a gas stream (9) discharged at the outlet of the regenerator, the facility comprising a facility outlet for discharging a treated gas stream (90), the facility outlet being connected to the feed line for feeding the regenerator.

Description

FLUIDIZED CATALYTIC CRACKING UNIT COMPRISING AN ELECTROLYSER

[0001] The present invention relates in particular to a fluidized catalytic cracking unit for the production of refined hydrocarbon products, the unit comprising at least one catalyst regenerator. STATE OF THE ART

[0002] Fluidized catalytic cracking is a process widely used in the refining industry.

[0003] Illustrates, schematically, a known fluidized catalytic cracking unit. It comprises a reactor 1 in which the cracking of heavy fractions resulting from the separation of crude oil 2 takes place thanks to the presence of a catalyst 3 injected into the reactor, and coming from a catalyst regenerator 4.

[0004] The products 5 from the catalytic cracking reaction, at the outlet of reactor 1, are separated from each other in a separation unit 6 and are recovered: they include in particular gas 51, kerosene 52, gasoline 53 etc.

[0005] Catalyst 3 becomes covered in coke in reactor 1 after cracking the crude oil. It becomes largely unusable in this state: it will be called spent catalyst 7.

[0006] The spent catalyst 7 is reinjected into the regenerator 4. The oxygen from the air 8 introduced into the regenerator 4 allows the coke to be burned and catalyst 3 to be reformed, which can then be used again for cracking the crude oil. It is then reinjected into the reactor 1.

[0007] A gas flow 9 is discharged at the outlet of the regenerator 4: it includes in particular carbon oxides (mostly carbon dioxide, CO2), nitrogen oxides (NOx), sulfur oxides (SOx), water, oxygen, etc.

[0008] Such a cracking unit has several disadvantages: –in particular, it leads to a heat loss, due to the use of air 8 which requires heating the nitrogen contained in the air. The heat loss is also due to the high temperatures at the gases leaving the regenerator zone 4.

[0009] The invention aims to limit energy consumption at a time when it is necessary to reduce carbon emissions and pollution in general.

[0010] Furthermore, reactor 1 and regenerator 4 require a lot of heat to enable the cracking reaction and catalyst regeneration respectively. In order to limit the energy consumption of reactor 1, water vapor is injected into it so that the temperature at the reactor inlet approaches that required to enable the reaction.

[0011] A first objective of the invention is to recover the energy produced in the cracking unit to reuse it in order to limit the energy input required for its operation.

[0012] A second objective of the invention is to use oxygen-enriched air in the regenerator, to limit the formation of NOx and thus simplify the post-treatment of the fumes. The invention also seeks to avoid the presence of nitrogenous products which are not desirable in the products which are to be produced or used.

[0013] To this end, the invention relates to a fluidized catalytic cracking unit comprising:- a reactor, capable of allowing the petroleum fraction cracking reaction in the presence of a catalyst,- at least one catalyst regenerator designed to supply the reactor with catalyst and to be supplied by the reactor with spent catalyst.

[0014] The fluidized catalytic cracking unit is remarkable in that it comprises a solid oxide electrolyser capable of producing dioxygen and dihydrogen from a first stream comprising in particular water vapour, the solid oxide electrolyser comprising a first dioxygen discharge outlet and a second dihydrogen discharge outlet, said first outlet being connected to the catalyst regenerator by means of a supply line to said regenerator, to supply an inlet to said regenerator with dioxygen.In addition, the unit comprises an installation for treating a gas stream discharged at the outlet of said regenerator, said gas stream comprising the residual gases from the regeneration of said catalyst, said treatment installation comprising an installation outlet for discharging a treated gas stream, said installation outlet being connected to said supply pipe of said regenerator to mix at least a portion of said treated gas stream with the oxygen produced by said electrolyser before its introduction into said regenerator.

[0015] The use of the solid oxide electrolyser makes it possible, on the one hand, to supply the quantity of oxygen introduced into the regenerator while producing dihydrogen which can be recovered and stored for other domestic or industrial uses. Furthermore, the user of the gas flow treated at the outlet of the regenerator makes it possible to dilute the quantity of oxygen introduced into the regenerator, which limits the production of heat possibly lost produced by the regenerator and to homogenize the combustion. Finally, the unit according to the invention avoids the presence of nitrogen compounds in the fumes of the regenerator and in the products of the reactor.

[0016] According to an advantageous embodiment, the treatment installation comprises a heat recovery unit which produces a second flow of water vapor, said heat recovery unit comprising a pipe for discharging the second flow of water vapor which is connected to one of the inlets of the reactor.

[0017] Furthermore, said heat recovery unit comprises a second discharge pipe for a third stream of water vapor which is connected to the inlet of said electrolyzer to supply it. This ensures an additional heat supply at the inlet of the electrolyzer.

[0018] Preferably, said treatment installation comprises a filter for retaining solid particles or dust resulting from the catalyst regeneration reaction, or possibly from the degradation of the catalyst, and in that said treatment installation produces a gas flow comprising carbon dioxide, constituting said gas flow mixed with oxygen before entering said regenerator. This allows production of treated gas, at the outlet of the regenerator, which does not contain nitrogen products.

[0019] More preferably, the treatment plant further comprises a water recovery device and a sulfur oxide recovery device. This ensures more precise filtering of the gases discharged from the regenerator.

[0020] Advantageously, said treatment installation comprises an evacuation pipe which is connected to the inlet of said electrolyser: this embodiment allows co-electrolysis and ensures an additional heat supply for the electrolyser.

[0021] According to an advantageous embodiment, the electrolyser is positioned in a sealed temperature maintenance chamber.

[0022] The invention also relates to a method for implementing a cracking unit as defined above, comprising a reactor, at least one catalyst regenerator, a heat recovery unit, a solid oxide electrolyser and a gas stream treatment plant. The method according to the invention comprises the following steps: - said solid oxide electrolyser is supplied with a first stream comprising in particular water vapour and generates, on the one hand, dihydrogen which is recovered downstream of said electrolyser, and on the other hand dioxygen which is injected into said regenerator, and

[0023] - said treatment installation generates a flow of treated gas which is mixed with said oxygen before its introduction into said regenerator.

[0024] The method according to the invention can ensure the implementation of a cracking unit as defined above and comprising a heat recovery unit, the reactor comprising several inlets, the heat recovery unit producing a flow of water vapor which can be injected at one of the inlets of said reactor.

[0025] The method can also be implemented by a unit according to the invention which comprises a heat recovery unit which produces another stream of water vapor which is also injected at the inlet of said solid oxide electrolyzer.

[0026] Furthermore, the method according to the invention uses a unit as defined above, the treatment installation of which produces a treated gas stream without product comprising nitrogen and, in accordance with the method, said treated gas stream is also injected into said solid oxide electrolyser in particular to produce synthesis gas (syngas).

[0027] Finally, according to an advantageous variant of the process according to the invention, implementing a cracking unit whose solid oxide electrolyser comprises a temperature maintenance chamber, the temperature in the temperature maintenance chamber is between 650°C and 850°C.

[0028] LIST OF FIGURES

[0029] Other features and advantages of the invention will appear on reading the detailed description of implementations and embodiments which are in no way limiting, and the appended drawings where:

[0030] illustrates the State of the Art, as indicated above,

[0031] is a schematic representation of a cracking unit according to a first embodiment according to the invention,

[0032] is a schematic representation of a cracking unit according to a second embodiment according to the invention,

[0033] is a schematic representation of a cracking unit according to a third embodiment according to the invention, and

[0034] is a schematic representation of a cracking unit according to a fourth embodiment according to the invention

[0035] References have been kept from one figure to another to define the same elements.

[0036] DESCRIPTION OF EMBODIMENTS

[0037] The embodiments which will now be described are not limiting: it will be possible in particular to produce variants of the invention comprising only a selection of characteristics described below, isolated from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art.

[0038] Of course, the invention is not limited to the examples which will be described and numerous adjustments can be made to these examples without departing from the scope of the invention. In addition, the various characteristics, forms, variants and embodiments of the invention can be associated with each other in various combinations to the extent that they are not incompatible or exclusive of each other.

[0039] Schematically illustrates a first embodiment of a cracking unit according to the invention.

[0040] We observe reactor 1, in which the catalytic cracking of petroleum fractions 2 is carried out using a catalyst 3: petroleum fraction 2 feeds reactor 1 and enters a riser 10 of reactor 1 where it mixes with water vapor and catalyst 3.

[0041] The internal temperature of the reactor is between 450 and 550 °C, and the pressure is between 1 and 3 Bars (absolute), to allow the catalytic cracking reaction.

[0042] Catalyst 3 comes from a pipe 30 of regenerator 4: it enters the riser 10 of reactor 1. In riser 10, the petroleum fraction is vaporized by water vapor in injectors. These injectors are located at the riser. Then, they are cracked into smaller molecules as the mixture is heated and reacts with catalyst 3, which produces lighter hydrocarbons with smaller chains which are evacuated (see products 5 from cracking, shown in).

[0043] The spent catalyst (reference 7) is thus separated from the products 5 in reactor 1 and is evacuated to the regenerator 4 via a pipe 70.

[0044] To regenerate the used catalyst 7 and transform it back into a useful catalyst 3, the coke present on the catalyst must be burned.

[0045] To do this, the regenerator must have oxygen and be brought to a high temperature, between 650 and 800°C, at a pressure between 1 and 3 Bars (absolute).

[0046] In accordance with the invention, and according to the first embodiment presently described, the cracking unit comprises a solid oxide electrolyzer 100 which produces dioxygen and dihydrogen 12 from water vapor and air V1 which feeds it.

[0047] The oxygen 11 is brought to the inlet 41 of the regenerator 4 by means of a feed pipe 40, to be injected there, and it is used to regenerate the spent catalyst 7 by allowing the coke which adheres to the spent catalyst to be burned.

[0048] The dihydrogen 12 is, for its part, recovered and evacuated from the electrolyser 100 via another pipe 42.

[0049] At outlet 43 of the regenerator, a residual gas flow 9 is recovered: it essentially (but not exclusively) comprises carbon dioxide, carbon monoxide, various particles, water, sulfur dioxide, nitrogen dioxide, nitrogen monoxide, etc.

[0050] In accordance with the invention, the cracking unit comprises a treatment installation 110 which aims to use the gas flow and the energy produced by the regenerator 4 to contribute to its operation, so as to reduce the external energy consumption necessary for its operation.

[0051] To do this, and initially, the treatment installation 110 comprises a heat recovery device HRU (Heat Recovery Unit) which uses the heat at the outlet 43 of the regenerator and / or uses the heat emanating directly from the regenerator to produce a second stream of water vapor V2 which is conducted to the inlet of the reactor 1, in the riser 10, to be used for catalytic cracking.

[0052] The treatment installation 110 also comprises other devices, such as particle filters 111, which retain the residual particles in the flow leaving the regenerator, a water collector 112 and a device for recovering compounds possibly comprising sulfur and / or nitrogen 113.

[0053] Thus, at the outlet of the treatment plant 110, we obtain a treated gas stream 90, rich in carbon oxides. More precisely, the gas is rich in carbon dioxide with possibly a little carbon monoxide. Indeed, in the regenerator, the total combustion of the coke is sought which leads to introducing more oxygen into the regenerator to avoid having carbon monoxide and to avoid post-combustion downstream.

[0054] This treated gas flow 90 is reused by being partially introduced into the supply line 40 of the regenerator, where it mixes with the oxygen in order to dilute it in quantity, to avoid too great a rise in temperature of the regenerator 4.

[0055] The quantity of oxygen 11 introduced into the regenerator 4 can thus be controlled.

[0056] By introducing oxygen from the electrolyzer, the presence of NOx is limited in the regenerator since the air no longer serves as an oxygen reservoir to allow the combustion of coke on the spent catalyst. In addition, this solution ensures a limitation of the nitrogen that is carried by the catalyst flow and returned to the reactor and therefore, to the final products.

[0057] Furthermore, if certain nitrogenous products are present initially, during the operation of the assembly described and represented in the figures, these nitrogenous products are retained by specific conversion units. They therefore do not intervene negatively in the capture of the CO2 produced by the regenerator.

[0058] It should be noted that the flow of treated gas 90, at the outlet of the treatment installation; can be partially directed towards an annex recovery device 114 for uses other than that aimed at diluting the quantity of oxygen introduced into the regenerator.

[0059] The advantage of such a cracking unit is to simplify the treatment of the gas stream leaving the regenerator since it does not contain as many undesirable products as when the regenerator is supplied with ambient air.

[0060] Another advantage of the cracking unit presently described is to allow the production of dihydrogen (H2), in addition to the other products 5 resulting from the catalytic cracking reaction, and to optimize the energy that it produces and consumes.

[0061] Illustrates an alternative embodiment of the cracking unit according to the invention.

[0062] As in the embodiment shown in, the cracking unit comprises a reactor 1, in which the catalytic cracking of a petroleum fraction 2 is carried out by means of a catalyst 3 which comes from a regenerator 4 via the pipe 30: the petroleum fraction 2 feeds the reactor 1 and enters a riser 10 of the reactor 1 where it mixes with water vapor in injectors and with the catalyst 3.

[0063] Lighter hydrocarbons 5 with smaller chains are evacuated.

[0064] The spent catalyst (reference 7), separated from the products 5 in reactor 1, is evacuated to the regenerator 4 via a pipe 70.

[0065] The cracking unit also includes a solid oxide electrolyzer 100 which produces oxygen 11 and hydrogen 12 from water vapor V1 which feeds it.

[0066] Dioxygen 11 feeds regenerator 4: it is used to regenerate the spent catalyst 7 by burning the coke which adheres to the spent catalyst.

[0067] The dihydrogen 12 is recovered and removed from the electrolyzer 100.

[0068] In this way, it is not necessary to introduce air into the regenerator and the nitrogen, included in the air, does not form nitrogen compounds (nitrogen monoxide or nitrogen dioxide) NOx which would end up both in the fumes of the regenerator and the final products in the reactor.

[0069] A residual gas flow 9 is discharged from the regenerator 4 and conducted to a treatment installation 110.

[0070] The treatment installation 110 comprises a heat recovery device HRU (Heat Recovery Unit) which uses the heat at the outlet 43 of the regenerator and / or uses the heat emanating directly from the regenerator to produce a second stream of water vapor V2 which is conducted to the inlet of the reactor 1, in the riser 10, to be used for catalytic cracking.

[0071] In the context of this embodiment, the heat recovery device HRU produces a third stream of water vapor V3 which is conducted to the electrolyzer 100: this third stream of water vapor can either allow the electrolyzer, which is located in a chamber that ensures its temperature is maintained, to be kept at between 650°C and 850°C. This third stream can also be used as a feed for electrolysis and the production of oxygen and hydrogen. Alternatively, this third stream of steam can either be used in the unit for conventional FCC functions, or be used for electrolysis, or even both.

[0072] As in the previous example, the treatment installation 110 also comprises other devices, such as particle filters 111, which retain the residual particles in the flow leaving the regenerator, a water collector 112 and a device for recovering the compounds possibly comprising compounds comprising sulfur and / or nitrogen 113.

[0073] Thus, at the outlet of the treatment installation 110, a treated gas flow 90 is obtained, comprising carbon oxides (but devoid of compounds containing nitrogen, like the previous examples).

[0074] This treated gas flow 90 is reused by being partially introduced into the supply line 40 of the regenerator, where it mixes with the dioxygen 11 in order to dilute it in quantity, to avoid too great a rise in temperature of the regenerator 4.

[0075] The other part of the treated gas flow 90 is directed towards an annex recovery device 114 for other uses.

[0076] The advantage of such a cracking unit, compared to the cracking unit presented in, is that the energy produced by the regenerator is optimally used for the operation of the electrolyser and the reactor.

[0077] This illustrates another variant of the implementation:

[0078] As in the previous examples, the cracking unit comprises a reactor 1, in which the catalytic cracking of a petroleum fraction 2 is carried out using a catalyst 3.

[0079] Catalyst 3 comes from a pipe 30 of regenerator 4 and enters the riser 10 of reactor 1. In riser 10, the crude oil (or part thereof) is vaporized by water vapor in injectors. These injectors are located at the riser. Then, they are cracked

[0080] The petroleum fraction 2 is vaporized and then cracked into smaller molecules, forming lighter products with smaller chains 5 which are evacuated from reactor 1.

[0081] The used catalyst (reference 7) is discharged to the regenerator 4 via a pipe 70.

[0082] The cracking unit also includes a solid oxide electrolyzer 100 which produces oxygen 11 and hydrogen 12 from water vapor V1. Optionally, sweep air is used at the inlet of the electrolyzer 100 and is found with the oxygen produced.

[0083] The oxygen 11 is brought to the inlet 41 of the regenerator 4 by means of a feed pipe 40, to be injected there, and it is used to regenerate the spent catalyst 7 by allowing the coke which adheres to the spent catalyst to be burned.

[0084] The dihydrogen 12 is, for its part, recovered and evacuated from the electrolyser 100 via another pipe 42.

[0085] At outlet 43 of the regenerator, a residual gas flow 9 is recovered, as in the previous examples: it essentially (but not exclusively) comprises carbon dioxide, carbon monoxide, various particles, water, etc.

[0086] Furthermore, the cracking unit may comprise a treatment installation 110 which comprises a heat recovery device HRU, particle filters 111, a water recovery unit 112 and a device for recovering compounds comprising sulfur and nitrogen 113.

[0087] As indicated above, the HRU allows in particular to create water vapor from the heat recovered at the outlet or emanating from the regenerator and transmits this flow of water vapor V2 to the reactor for the catalytic cracking reaction.

[0088] At the outlet of the treatment installation 110, a treated gas stream 90 is obtained, which includes carbon oxides.

[0089] As in the previously described embodiments, this treated gas flow 90 is reused by being partially introduced into the supply line 40 of the regenerator, where it mixes with the oxygen 11 in order to dilute it in quantity.

[0090] According to this embodiment illustrated in, instead of recovering in an additional device 114 the treated gas flow 90 which is not reinjected into the pipe 40, the gas flow not mixed with the oxygen introduced into the regenerator is injected into the electrolyser 100 to carry out co-electrolysis: in fact, according to this variant embodiment, the treated flow 90 is used to supply the electrolyser in order to produce carbon monoxide 13 which is evacuated with the dihydrogen 12 (the mixture of dihydrogen and carbon monoxide forming the syngas finding uses in the industrial or domestic field) via the pipe 42 at the outlet of the electrolyser.

[0091] Such a cracking unit makes it possible to avoid producing CO2, to produce syngas useful for ancillary applications and, as in the previous examples, to allow the treatment of a gas stream 9, at the outlet of the regenerator, which does not contain nitrogen products.

[0092] The term “syngas” means a synthesis gas that can be used directly as a gaseous fuel or transformed into liquid fuel.

[0093] Another embodiment is illustrated in: it combines the embodiments of figures 3 and 4 and constitutes yet another variant embodiment of the cracking unit according to the invention:

[0094] The cracking unit comprises a reactor 1, in which the catalytic cracking of an oil fraction 2 is carried out by means of a catalyst 3.

[0095] Catalyst 3 comes from a pipe 30 of regenerator 4 and enters the riser 10 of reactor 1, in which it mixes with water vapor V2 produced by the HRU of the treatment plant, downstream of regenerator 4.

[0096] The petroleum fraction 2 is vaporized and then cracked into smaller molecules, forming lighter products with smaller chains 5 which are evacuated from reactor 1.

[0097] The used catalyst (reference 7) is discharged to the regenerator 4 via a pipe 70.

[0098] The cracking unit also includes a solid oxide electrolyzer 100 which produces oxygen 11 and hydrogen 12 from water vapor V1 which feeds it.

[0099] The oxygen 11 is brought to the inlet 41 of the regenerator 4 by means of a feed pipe 40, to be injected there, and it is used to regenerate the spent catalyst 7 by allowing the coke which adheres to the spent catalyst to be burned.

[0100] The dihydrogen 12 is, for its part, recovered and evacuated from the electrolyser 100 via another pipe 42.

[0101] At outlet 43 of the regenerator, a residual gas flow 9 is recovered: it essentially (but not exclusively) comprises carbon dioxide, carbon monoxide, various particles, water, sulfur dioxide, nitrogen dioxide, nitrogen monoxide, etc.

[0102] Furthermore, the cracking unit may comprise a treatment installation 110 which comprises a heat recovery device HRU, particle filters 111, a water recovery unit 112 and a device for recovering compounds comprising sulfur and nitrogen 113.

[0103] As indicated above, the HRU allows in particular to create water vapor from the heat recovered at the outlet or emanating from the regenerator and transmits this flow of water vapor V2 to the reactor for the catalytic cracking reaction.

[0104] At the outlet of the treatment installation 110, a treated gas stream 90 is obtained, which includes carbon oxides.

[0105] The treated gas stream 90 is reused by being partially introduced into the supply line 40 of the regenerator, where it mixes with the oxygen 11 in order to dilute it in quantity.

[0106] As for the example illustrated in, the stream 90 is also injected into the electrolyzer 100 to carry out co-electrolysis, in order to produce dioxygen 11, dihydrogen 12 and carbon monoxide 13 (syngas).

[0107] As in the example illustrated in, the HRU is also designed to produce a third stream of water vapor V3 which feeds the electrolyzer 100.

[0108] In this latter embodiment, the heat produced by the regenerator is reused both to supply reactor 1 with a flow of water vapor useful for the cracking unit, and to ensure part of the production of oxygen.

[0109] This latter embodiment combines the advantages of the cracking units illustrated in Figures 3 and 4: the production of syngas, the non-production of CO2, and the use of the energy produced by the regenerator to optimize the operation of the electrolyser in terms of recovery of energy produced by a first device (regenerator) and reuse of this energy by another device (the electrolyser).

[0110] It is understood from the above description that the invention makes it possible to use part of the products or energy created by the catalyst regenerator in order to optimize the operation of the cracking unit, without having to provide additional energy from outside the unit, nor to use ambient air to supply the regenerator with oxygen: thus, the products that can hinder regeneration, such as nitrogen monoxide or nitrogen dioxide, are not produced and thus do not end up in the fumes of the regenerator but also not in the final products of the reactor. The operation of the regenerator is thus optimized.

Claims

Fluidized catalytic cracking unit comprising:- a reactor (1), capable of allowing the cracking reaction of petroleum fractions (2) in the presence of a catalyst (3),- at least one catalyst regenerator (4) designed to supply the reactor (1) with catalyst (3) and to be supplied by the reactor (1) with spent catalyst (7),characterized in that it comprises a solid oxide electrolyser (100) capable of producing dioxygen (11) and dihydrogen (12) from a flow comprising in particular water vapour (V1), the solid oxide electrolyser (100) comprising a first dioxygen evacuation outlet (11) and a second dihydrogen evacuation outlet (12), said first outlet being connected to the catalyst regenerator (4) by means of a supply line (40) of said regenerator (4), to supply an inlet (41) of said regenerator (4) with dioxygen (11),and in that it comprises an installation (110) for treating a gas flow (9) discharged at the outlet of said regenerator (4), said gas flow (9) comprising the residual gases from the regeneration of said catalyst, said treatment installation (110) comprising an installation outlet for discharging a treated gas flow (90), said installation outlet being connected to said supply pipe (40) of said regenerator (4) to mix at least a portion of said treated gas flow (90) with the dioxygen (11) produced by said electrolyser (100) before its introduction into said regenerator (4)., Cracking unit according to claim 1, characterized in that said treatment installation (110) comprises a heat recovery unit (HRU) which produces a second flow of water vapor (V2), said heat recovery unit (HRU) comprising a pipe for discharging the second flow of water vapor (V2) which is connected to one of the inlets of the reactor (1). Cracking unit according to claim 2, characterized in that said heat recovery unit (HRU) comprises a second evacuation pipe for a third flow of water vapor (V3) which is connected to the inlet of said electrolyzer (100) to supply it. Cracking unit according to any one of the preceding claims, characterized in that said treatment installation (110) comprises a filter (111) for retaining solid particles or dust resulting from the catalyst regeneration reaction and / or from the degradation of the catalyst, and in that said treatment installation (110) produces a gas flow comprising carbon dioxide, constituting said gas flow (90) mixed with dioxygen (11) before its entry into said regenerator (4). Cracking unit according to claim 4, characterized in that said treatment installation (110) further comprises a water recovery device (112) and a sulfur dioxide recovery device (113). Cracking unit according to any one of the preceding claims, characterized in that said treatment installation (110) comprises a discharge pipe which is connected to the inlet of said electrolyser (100). Cracking unit according to any one of the preceding claims, characterized in that the electrolyser (100) is positioned in a sealed temperature maintenance chamber. A method of implementing a cracking unit according to any one of the preceding claims, comprising a reactor (1), at least one catalyst regenerator (4), a heat recovery unit, a solid oxide electrolyser (100) and a gas stream treatment plant (110), said method comprising the following steps: - said solid oxide electrolyser (100) is supplied with a first stream of water vapour (V1) and generates, on the one hand, dihydrogen (12) which is recovered downstream of said electrolyser (100), and on the other hand dioxygen (11) which is injected into said regenerator (4), and - said treatment plant (110) generates a stream of treated gas (90) which is mixed with said dioxygen (12) before its introduction into said regenerator (4). Method according to claim 8, ensuring the implementation of a cracking unit according to claim 2 or 3, characterized in that said reactor comprises several inlets and in that said heat recovery unit (HRU) produces a second flow of water vapor (V2) injected at one of the inlets of said reactor (1). Method according to claim 9, characterized in that it comprises a third flow of water vapor (V3) is also injected at the inlet of said solid oxide electrolyzer (100). Method according to any one of claims 8 to 10, characterized in that said treatment installation (110) produces a treated gas flow (90) without product comprising nitrogen and in that said treated gas flow (90) is also injected into said solid oxide electrolyser (100) in particular to produce a synthesis gas. Method according to any one of claims 8 to 11, implementing a cracking unit according to claim 7, the solid oxide electrolyser (100) of which comprises a temperature maintenance chamber, characterised in that the temperature in the temperature maintenance chamber is between 650°C and 850°C.

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