Optimized production of hydrogen from hydrocarbons

Abstract

The present invention relates to a method for producing an outlet gas containing molecular hydrogen, comprising injecting an inlet hydrocarbon gas (1) into a reactor (11), subjecting the inlet gas (1) to a cracking operation using a three-phase plasma torch (12), and then conveying the outlet gas (3). The production is carried out from the injection of the inlet gas (1) into the reactor (11) until the conveyance of the outlet gas (3), without either the inlet gas (1) or the outlet gas (3) undergoing expansion.

Description

Field of the Invention

[0001] The present invention relates to the production of dihydrogen from hydrocarbons. More specifically, it finds application in the energy field and thus plays a crucial role in energy conversion. It can also be advantageously applied to the fueling of hydrogen fuel vehicles or in industry where the engine unit does not directly emit greenhouse gases.

[0002] State of the art

[0003] In the current context, there is a great deal of interest in solutions that seek to address energy challenges. Climate change, resource scarcity, and the multiplication of environmental health risks are the consequences of economic and social models that need to change.

[0004] Ecological transition is a change towards a new sustainable development model that renews consumption habits, production processes, ways of working and living, in order to meet major environmental challenges.

[0005] Hydrogen is generally considered to be the energy of the future. It is the ultimate form of a carbon-free fuel. However, its current production is accompanied by a large amount of carbon dioxide emissions, approximately 12 kg of carbon dioxide per kg of dihydrogen produced using the steam methane reforming method, which is the main method of reforming fossil resources - accounting for 98% of the world's dihydrogen production. Despite its low cost, the total amount of carbon dioxide emitted into the environment by this type of method is 720 million tons per year, accounting for 2.25% of global carbon dioxide emissions.

[0006] Many methods or devices that allow the production of low-carbon hydrogen have been studied. The most well-known of these is water electrolysis.

[0007] Water electrolysis is a method that requires the installation of a device that consumes a large amount of electrical energy and is therefore relatively expensive. In addition, endowing the hydrogen produced by electrolysis with a non-carbon character requires electricity from a non-carbon source, which makes the method highly dependent on renewable energy. Renewable energy is already struggling to replace traditional, polluting methods of electricity generation and, whether now or in the near future, will not be able to meet the growing electricity consumption for the production of hydrogen by electrolysis.

[0008] Finally, there is a method that overcomes the above limitations and produces hydrogen without emitting carbon dioxide and at a much lower cost than electrolysis. This method is the plasma cracking of hydrocarbons. The theoretical electricity consumption of this method is equal to the production of 5.27 kWh / kg of dihydrogen, compared to 39.4 kWh / kg of dihydrogen produced by water electrolysis.

[0009] Plasma cracking of hydrocarbons is a method known in the prior art. However, it should be noted that, so far, this method has mainly been used for the production of carbon products and does not always allow the production of hydrogen as the main product and at a competitive cost.

[0010] In fact, the cracking operation consists of decomposing hydrocarbon molecules into smaller elements. The carbon products of this operation can be gaseous or partially solid.

[0011] Therefore, scientific and economic issues have led to the development of hydrocarbon cracking operations in the implementation of devices that allow the production of solid or gaseous carbon products, without seeking to utilize the hydrogen formed during the operation.

[0012] In practice, the carbon products are retained, while the hydrogen present in the gas phase remains a by-product that is not utilized by the process.

[0013] Therefore, the prior art demonstrates a well-known method in which a plasma jet cracks hydrocarbons to substantially extract carbon black or alkynes or alkenes.

[0014] The plasma cracking of hydrocarbons ultimately results in the release of hydrogen in the form of dihydrogen. Then, the hydrogen released by the reaction is considered a by-product because the process previously focused on carbon products.

[0015] In order to be able to guarantee hydrogen as an available product, for example in the field of mobility, the hydrogen must be conditioned at a pressure of several hundred bars.

[0016] Therefore, the existing methods are not optimal for hydrogen production.

[0017] Document FR2474043A1 discloses a method for cracking hydrocarbons using a plasma torch, with nitrogen and oxygen as carrier gases in proportions that can be found in air. The cracking is carried out to substantially produce carbon products, namely to produce "carbon black".

[0018] In document US2016 / 2296905A1, it is disclosed that hydrocarbons are cracked by using a tubular electrode torch, and then a maze is used at a process gas flow rate of approximately 1 m 3 / h to separate dihydrogen and carbon by gravity trapping of the carbon products. The main purpose of this type of solution is to produce carbon and recover the carbon after the operating cycle.

[0019] Therefore, it should be noted that in the existing solutions for producing hydrogen using hydrocarbon cracking, the hydrogen produced is usually a by-product, that is, a by-product mixed with other chemical elements in the gas phase, and its conditioning does not allow efficient operation.

[0020] In summary, the production of hydrocarbons by plasma cracking operations does not allow the optimized production of dihydrogen as the main product, and there is a need to find methods and devices to improve the existing methods and devices.

[0021] Therefore, the object of the present invention is to provide an invention that aims to optimize and continuously produce hydrocarbons by plasma cracking operations, allowing the optimized and preferably continuous production of dihydrogen as the main product.

[0022] Further objects, features and advantages of the present invention will become apparent from the following description and the accompanying drawings. It should be understood that further advantages may also be included. Summary of the Invention

[0023] To achieve this object, according to one embodiment, a method for manufacturing an outlet gas containing dihydrogen is provided, including injecting a hydrocarbon inlet gas into a reactor, performing a cracking operation on the inlet gas by a plasma torch, and then conveying the outlet gas. The method is configured such that production is carried out from injecting the inlet gas into the reactor to conveying the outlet gas, and neither the inlet gas nor the outlet gas undergoes more than 20% expansion, the plasma torch is supplied with three-phase current, and the cracking operation of the inlet gas is carried out with plasma, and the carrier gas of the plasma is a mixture including hydrogen and / or hydrocarbon. The method includes at least one separation operation carried out downstream of the cracking operation to separate the outlet gas from the solid carbon product. Downstream of the separation operation, part of the outlet gas is used in the carrier gas.

[0024] Therefore, the method has the characteristic of being able to generate dihydrogen under pressure, preferably having a satisfactory purity level, and thus being easy to utilize.

[0025] As is well known from common methods, carbon products can be produced by a plasma cracking operation. In fact, what is provided here is an advantageous and optimized method that can be used to convert hydrocarbons into dihydrogen.

[0026] The conversion is preferably carried out by a plasma cracking operation in a pressurized reactor. The gaseous hydrocarbon is preferably injected into the reactor where the cracking operation is carried out under pressure.

[0027] At the outlet of the reactor, dihydrogen is advantageously conveyed without undergoing expansion, that is, the gas phase does not undergo expansion.

[0028] The method has the characteristics of hydrocarbon plasma cracking, but the cracking is preferably carried out under pressure to obtain the most utilizable dihydrogen possible thereafter.

[0029] Therefore, it is proposed to consider hydrogen as the main product of the reaction. According to one embodiment, the pressure of hydrogen at the outlet of the device is greater than or equal to the pressure at the inlet of the reactor, or there is no more than 20% loss because it passes through a device that prevents pressure change.

[0030] Advantageously, the dihydrogen at the outlet of the reactor is contained in the gas phase under pressure, which makes it possible to minimize the additional pressurization step at the outlet of the device. Therefore, the dihydrogen at the outlet of the device is more easily utilized. For example, it can be optimized to be used as a fuel gas for retrofitted vehicles.

[0031] In fact, when carried out at already high pressures (preferably above 4 bar), the pressurization step to bring hydrogen to the operating pressure (such as the pressure used in hydrogen fuel vehicles) is generally less complex and less expensive.

[0032] In the document FR2474043A1, a hydrocarbon plasma cracking operation is disclosed which allows the extraction of carbon products accompanied by gas emissions. This gas emission is not utilized as it is just a by-product which may in particular consist of contaminants. Moreover, this document does not seem to provide for any hydrogen production. The applicant points out that, contrary to intuition, the first bars of pressurization are the most expensive. In fact, to compress hydrogen from atmospheric pressure to 20 bar, the energy required is equivalent to that for the conversion from 20 bar to 350 bar. Specifically, the theoretical energy required to compress hydrogen from 1 bar to 20 bar is equal to 5.31 MJ / kg of dihydrogen. For the conversion from 20 bar to 350 bar, this energy is equal to 4.96 MJ / kg of hydrogen. On the other hand, the theoretical energy required to compress methane from 1 bar to 20 bar is equal to 0.61 MJ / kg of methane. Thus, even if the mass flow rate of methane to be compressed is four times the mass flow rate of hydrogen in the cracking process, the compression of upstream methane requires less than half of the energy required to compress downstream hydrogen. However, from the perspective of the process, the energy required to compress methane can be free as the natural gas supplier can guarantee a minimum connection pressure of up to 42 bar without additional cost.

[0033] Moreover, operation at pressure allows the plant to be compact and the size of the equipment to be reduced, thus reducing heat losses through the walls.

[0034] While conventional techniques suggest using a single-phase DC torch as in US2016 / 296905A1, a three-phase torch is advantageously used here. This plasma torch technology is particularly suitable for the production of dihydrogen by hydrocarbon cracking. In fact, the cracking reaction requires a residence time of more than one second to obtain a relatively high hydrogen production yield. Different from the known DC and tube electrode plasma torch technologies for high-speed plasma jets, the three-phase plasma torch has the ability to operate at a very low gas velocity of less than 2 m / s, preferably less than 1 m / s (if needed, about 1 m / s or less). Thus, this makes the three-phase plasma torch suitable for managing and controlling the residence time and thus the yield of the cracking reaction. As a direct result, for an equal residence time, the length of the reactor is shortened compared to a reactor connected to a DC plasma torch. In this way, the post-heat losses will be reduced.

[0035] On the other hand, the DC and tubular electrode technologies do not allow continuous operation as they require the equipment to be shut down to replace the electrodes after being corroded. In fact, replacing the electrodes during the operation of a tubular structure is very complex.

[0036] Another inherent advantage of the pressurized cracking operation using three-phase technology is that the head loss of the plasma gas is very low compared to DC technology with tubular electrodes, which involves a head loss of several bar, making the cracking operation starting from 4 bar unattractive for this technology as its use leads to a significant drop in the inlet pressure.

[0037] According to a preferred possibility of the present invention, hydrogen production is carried out continuously, in particular without stopping production to renew the electrodes, by using the reload system described in patent WO 2020229408A1.

[0038] The cracking reaction can be maintained there, with the carrier gas circuit being returned from the outlet gas to form a circulating assembly. Through such a cycle, and while maintaining the working gas volume, the applicant has noticed a very good yield, which results in hydrogen being obtained at pressure at the outlet (so not necessarily implying subsequent compression, or by limiting the energy impact), and reduces the electrical consumption of the torch.

[0039] The reinjection of part of the outlet gas as a carrier gas acts in synergy with the three-phase torch to control the cracking reaction, provided that this reinjection can reintroduce the residual hydrocarbons after cracking. It should be remembered that the volumetric latent heat of hydrocarbons is higher than that of the hydrogen-type light carrier gas, which includes a temperature increase in the reactor.

[0040] On the other hand, it relates to a device for preparing an outlet gas containing dihydrogen, which includes a pipeline for injecting hydrocarbon inlet gas into a reactor, the reactor includes a plasma torch configured to generate a cracking inlet gas operation, and a pipeline for transporting the outlet gas. The device is configured such that the inlet gas is transformed from being injected into the reactor to returning as an outlet gas without undergoing an expansion greater than 20%. The plasma torch is supplied with three-phase current, and the device is configured such that the operation of the cracking inlet gas is carried out with plasma, and the carrier gas of the plasma is a mixture including hydrogen and / or hydrocarbons. The device includes a separator located downstream of the reactor and configured to allow the gas mixture to be separated into an outlet gas and a solid carbon product at the reactor outlet, and the device is configured such that part of the outlet gas is reinjected into the carrier gas.

[0041] However, it should be noted that in practice, the aspect of not undergoing expansion can tolerate a perceptible drop in the relative pressure between the inlet gas and the outlet gas of one of the elements of the device, such as the reactor, filter or separator.

[0042] However, it should also be noted that with respect to the pressure of the gas leaving the said element of the device, this expansion does not exceed a pressure drop of 20% relative to the pressure of the inlet gas.

[0043] According to another separable aspect, there are provided an apparatus and a method for manufacturing an outlet gas containing dihydrogen such that the pressure of the dihydrogen-based gas generated by cracking is greater than 4 bar, and preferably greater than or equal to 5 bar, at least at the reactor outlet.

[0044] Preferably, alternatively or additionally, the pressure at the reactor outlet is greater than or equal to the pressure of the inlet gas entering the reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The objects, aims, features and advantages of the present invention will become more apparent from a detailed description of an embodiment of the present invention, which is illustrated by the following drawings, in which:

[0046] Figure 1 A simplified technical diagram showing the apparatus of the present invention.

[0047] Figure 2 Showing Figure 1 An alternative of the technical diagram of the shown apparatus.

[0048] The drawings and diagrams are always given by way of example and do not limit the present invention. They are representations of the principles for the purpose of facilitating the understanding of the present invention and are not necessarily on the scale of actual applications. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0049] Before starting a detailed review of the embodiments of the present invention, the following alternative features are listed, which can be used in combination or alternatively:

[0050] According to one embodiment, the injection of the inlet gas 1 is carried out at an injection pressure p2 greater than or equal to 4 bar.

[0051] According to one embodiment, this makes it possible to anticipate the regeneration of the hydrogen produced. In fact, once the inlet gas 1 is injected into the reactor 11, the cracking operation is advantageously carried out at an injection pressure p2 corresponding at least to the delivery pressure p3.

[0052] Therefore, the cracking operation can advantageously be carried out using pressurized reactants. In fact, injecting a pressurized gas mixture containing hydrocarbons into the reactor 11 makes it possible to anticipate the final pressurization of the product.

[0053] As a result, the pressure level reached before the cracking operation is preferably at least equal to 4 bar and does not decrease before hydrogen is obtained at the end of the method. Injecting the inlet gas 1 at a pressure of at least 4 bar maximizes the regeneration of the desired product (i.e., hydrogen) because the pressurization of H2 is ultimately necessary for its availability.

[0054] According to one embodiment, the minimum temperature at which the cracking operation can be carried out within the apparatus is 1200 °C.

[0055] According to one embodiment, the method includes compressing upstream of the injection reactor 11 to an injection pressure p2.

[0056] According to one embodiment, this makes it possible to ensure the above technical effect, that is, to inject the inlet gas 1 containing hydrocarbons into the reactor 11 at the injection pressure p2, and the value of the injection pressure p2 can be selected to optimize the correct operation of the method.

[0057] In fact, the compression finally allows the pressure of the inlet gas 1 to increase from the intake pressure p1 to the injection pressure p2.

[0058] According to one embodiment, the operation of cracking the inlet gas 1 is carried out with a plasma, and the carrier gas 2 of this plasma is a mixture of hydrogen and hydrocarbons.

[0059] According to one embodiment, at the start of the method, a hydrogen feedstock can be used as the carrier gas of the plasma.

[0060] Therefore, the injection of hydrocarbons can advantageously start, and the gas produced in the recycle reactor can be started to be recycled to supply the plasma. Then the initial supply of hydrogen can be stopped.

[0061] According to the above embodiment, it should be noted that the hydrogen used for startup is not lost, but is advantageously recovered as a product of the method. Therefore, in the absence of an external hydrogen supply, some of the hydrogen produced can be recovered to restart the method.

[0062] This makes it possible to increase the production yield and preferably not emit carbon dioxide. In fact, using a gas mixture including nitrogen and oxygen in the same proportion as in ambient air as the carrier gas 2 for the cracking operation may release carbon dioxide or produce toxic substances such as cyanides.

[0063] According to one embodiment, the method includes at least one separation operation carried out downstream of the cracking operation to separate the outlet gas 3 from the solid carbon product 4.

[0064] The separation operation may play a major role in the manufacture of the product, especially for separating the solid phase from the gas phase. In fact, the plasma cracking of hydrocarbons can lead to the formation of the carbon product 4 in solid form.

[0065] In fact, if the carbon product is mainly obtained in its solid phase, then the operation of cracking to produce hydrogen is more sensible.

[0066] Therefore, since the separation of the solid phase and the gas phase can be carried out, for example, by using a particle filter, it is beneficial to the purification of dihydrogen. Therefore, the remaining gas phase is more concentrated in hydrogen. This makes it easier to reach a higher hydrogen purity level.

[0067] According to one embodiment, downstream of the separation process, a portion of the outlet gas 3 is used in the carrier gas 2.

[0068] According to one embodiment, since the carrier gas 2 used is a mixture of hydrocarbons and hydrogen, its presence at the outlet of the reactor 11 advantageously allows it to be reinjected as the carrier gas 2.

[0069] In fact, reinjecting a mixture of hydrocarbons and hydrogen as the carrier gas helps to optimize the material yield of the present invention, wherein according to one embodiment, the hydrocarbons remaining in gaseous form after the cracking operation can act as the carrier gas 2. In the case of the present invention, the gas mixture produced by the cracking operation preferably consists of hydrogen and hydrocarbons and can therefore be reinjected as the carrier gas 2 without worrying about carbon dioxide emissions.

[0070] According to one embodiment, the method includes a filtration operation carried out downstream of the separation operation to produce a purified outlet gas 6 having a higher concentration of dihydrogen than the outlet gas 3.

[0071] This filtration operation preferably allows the last remaining hydrocarbon molecules to be separated from the desired dihydrogen. In fact, after the separation operation, the gas phase and the solid phase can be well and truly separated. However, in the gas phase, it is advisable to consider the presence of hydrocarbons, as well as the presence of small amounts of other chemical elements such as nitrogen, carbon dioxide, helium, or hydrogen sulfide (H2S), which can be advantageously filtered through the filter 10 or upstream of the injection into the reactor 8.

[0072] Thus, the filtration operation helps to optimize the desired product, i.e., pressurized dihydrogen, preferably with the highest possible degree of purity.

[0073] According to one embodiment, the purified outlet gas 6 is stored at a delivery pressure p3 greater than or equal to the injection pressure p2, preferably strictly greater than the injection pressure p2.

[0074] This allows the dihydrogen to be advantageously accumulated under pressure without worrying about product loss or dissipation. In fact, the hydrogen produced may require a storage container 15 in which the hydrogen can be stored and then preferably redistributed to allow its industrial or commercial exploitation.

[0075] According to one embodiment, the delivery pressure p3 is greater than or equal to 4 bar.

[0076] For example, this makes it possible to obtain and store the product at a more easily utilizable pressure. In fact, when the gas is at a low delivery pressure p3, increasing the pressure of the gas is more complex to implement.

[0077] According to one embodiment, with respect to the purified outlet gas 6, the filtration operation produces a hydrocarbon gas which is reinjected into the plasma reactor 11.

[0078] Preferably, with respect to the purified outlet gas 6, the filtration operation produces hydrocarbon gas, which is reinjected with the carrier gas.

[0079] This may increase the material yield and advantageously limit the hydrogen loss. In fact, at the end of the filtration operation, hydrocarbon residues may remain, which can then be reinjected into the reactor 11, where new extraction operations can then be carried out.

[0080] According to one embodiment, the inlet gas 1 is CH4.

[0081] According to one embodiment, a portion of the solid carbon product 4 is conveyed and stored.

[0082] According to one embodiment, the plasma torch 12 is supplied with three-phase current.

[0083] According to one embodiment, the cracking operation is carried out continuously by means of the plasma torch 12 provided with a continuous electrode supply system 5.

[0084] According to one embodiment, a portion of the outlet gas for the carrier gas comprises CH4.

[0085] According to one embodiment, a plasma torch is used, which is continuously supplied with electrodes, preferably preventing pressure changes in the reactor and without stopping the production of the outlet gas.

[0086] According to another embodiment, the device is configured such that the injection line 13 comprises a plurality of injection holes opening into the reactor 11 and oriented in different and radial directions with respect to the direction of the carrier gas flow 2 in the reactor 11.

[0087] This allows the hydrocarbon inlet gas 1 to be optimally distributed in the reactor 11 under pressure. In fact, according to one embodiment, in this way, an annular injection system is used which will have the function of ensuring good penetration of the inlet gas 1 in the carrier gas in the plasma state in the reactor 11.

[0088] According to another embodiment, the invention relates to a device which comprises an inlet compressor 7 for the inlet gas 1 to be placed on the injection line 13.

[0089] This ensures that the inlet gas 1 is injected into the reactor 11 at the injection pressure p2.

[0090] In fact, the inlet compressor 7 allows the pressure of the inlet gas 1 to be increased from the intake pressure p1 to the injection pressure p2.

[0091] According to another embodiment, the device in which the plasma torch 12 includes the electrode 5 is configured to have an active electrode that operates in the reactor 11 by continuous and sequential supply of the electrode and prevents pressure changes in the reactor 11. Thus, there is no pressure loss around the active electrode passing through the wall of the reactor 11.

[0092] This allows for pressure cracking operations. In fact, the reactor 11 is configured to include the electrode 5, which can allow cracking under pressure, which makes it possible to anticipate a possible second compression of the product. Thus, the pressure level reached before the cracking operation is not reduced to the final product.

[0093] According to another embodiment, the device prevents pressure changes in the injection line 13 from the reactor 11 until it returns from the outlet gas 3.

[0094] This makes it possible to at least maintain the gas phase under pressure during the conversion without having to undergo expansion.

[0095] In fact, the tightness of the device preferably allows cracking under pressure and retaining hydrogen without expansion.

[0096] According to another embodiment, the device includes an outlet compressor 8 downstream or upstream of the storage element 15, from the delivery pressure p3 until the operating pressure p4.

[0097] This can allow the hydrogen produced to be contained and subsequently used.

[0098] According to a specific embodiment, at least part of the solid carbon product 4 is transported and stored.

[0099] This also optimizes the conversion yield and increases the production of the carbon product 4 (i.e., solid carbon) to produce hydrogen. In fact, in one embodiment, the plasma cracking operation allows for the optimization of the production of solid carbon from hydrocarbons.

[0100] Advantageously, hydrogen production is accompanied by solid carbon by-products, which do not affect the energy yield per kg of hydrogen. Thus, the cracking operation for hydrogen production can be carried out at a temperature above 1200 °C.

[0101] As long as the rise to high temperatures is avoided, the cracking operation is preferably energy-saving.

[0102] Furthermore, for example, carbon black type production requires high temperatures, preferably around 2000 °C, which reduces the energy balance per kg of hydrogen of the method.

[0103] Preferably, the plasma torch 12 is supplied with three-phase current.

[0104] In fact, by using, for example, a three-phase plasma torch technology 12 to heat with a mixture of hydrogen and hydrocarbon as the carrier gas 2, the present invention thus has the necessary energy configuration to crack hydrocarbons under pressure.

[0105] In fact, the three-phase plasma torch technology is particularly suitable for this hydrogen production method because it has the ability to operate at a relatively low carrier gas velocity, which allows an increase in residence time and optimization of hydrogen production.

[0106] According to a specific embodiment, the cracking operation is carried out continuously.

[0107] In fact, by means of using a plasma torch 12 equipped with a continuous electrode supply system 5, the hydrocarbon cracking for hydrogen production advantageously operates continuously.

[0108] According to a specific embodiment, the device is configured such that the cracking of the inlet gas 1 occurs at the injection pressure p2 and then passes through an element that prevents pressure changes.

[0109] Therefore, according to one embodiment, the circulation of the reactants under pressure is beneficial for a device equipped with a plasma arc torch.

[0110] This is because the pressure increase in the device can drive the arc to an operating point with a voltage greater than or equal to the voltage associated with the operation at atmospheric pressure at equal power.

[0111] Therefore, according to this embodiment, the working current under pressure is lower at equal power than at atmospheric pressure.

[0112] According to a specific embodiment, the device is configured to:

[0113] - where part of the solid carbon product 4 is transported and stored in a storage element dedicated to the storage of the carbon product 4.

[0114] - where the plasma torch 12 is supplied with three-phase current.

[0115] - where the cracking operation is carried out continuously by means of using a plasma torch 12 equipped with a continuous electrode supply system 5.

[0116] According to a specific embodiment, the injection line 13 of the device is configured to include a plurality of injection holes that are oriented in different and radial directions with respect to the flow direction of the carrier gas 2 in the reactor 11.

[0117] According to a specific embodiment, the device is configured with an inlet compressor 7 for the inlet gas 1 placed on the injection line 13.

[0118] According to a specific embodiment, the device is configured such that the plasma torch 12 includes an electrode 5, and the electrode 5 is configured to continuously supply to prevent pressure changes within the reactor 11.

[0119] According to a specific embodiment, the device is configured to prevent pressure changes from the injection line 13 into the reactor 11 until it returns from the exit gas 3.

[0120] According to a specific embodiment, the device is configured such that it includes an outlet compressor 8 downstream or upstream of the storage element 15, configured to increase the pressure of the exit gas 3 from the delivery pressure p3 to the operating pressure p4. It is noted that within the scope of the present invention, the term "hydrogen" is repeatedly used as the product targeted by the method and may include the synonymous term "dihydrogen", which refers to the molecular form of elemental hydrogen that can exist in gaseous form under the temperature and pressure conditions provided by the device.

[0121] Furthermore, it should be noted that the "hydrocarbon" used in the method and device is preferably methane, referred to as "CH4". Within the scope of the present invention, it can also be an implementation of cracked methane or biogas containing hydrocarbons or mixtures mainly containing CH4.

[0122] Thus, according to one embodiment, the inlet gas 1 consists of hydrocarbons, which, literally speaking, are composed essentially of carbon atoms and hydrogen atoms.

[0123] A distinction should be made between the different physical states of the reactants and products involved in the method and device of the present invention.

[0124] It should also be noted that the term "carbon product" is distinguished from the reactants as the product of the cracking reaction that includes most carbon atoms.

[0125] For example, a distinction can be made between the "gas phase" and the "solid phase", where the "gas phase" corresponds to any reactant or product that is in gaseous form from the inlet gas to the delivery cycle within the device, while the "solid phase" is, for example, present as solid carbon products.

[0126] The object of the present invention is to produce a product consisting essentially of gaseous hydrogen. Therefore, particular attention should be paid to the chemical elements present in gaseous form.

[0127] It is noted that within the scope of the present invention, the term "inlet gas" 1 includes the gas phase that enters at the start of the method. Therefore, prior to the cracking operation, preferably the inlet gas 1 is the only gas phase considered.

[0128] Preferably, the inlet gas can extend to any hydrocarbon that is gaseous or can be converted to gaseous - for example from liquid, especially by spraying.

[0129] It is noted that within the scope of the present invention, the term "carrier gas" 2 - which may include the gas required to effect the discharge in the reactor 11 - may also be referred to as the carrier gas.

[0130] Furthermore, within the scope of the present invention, it should be noted that the term "exit gas" 3 includes the gas phase at the exit of the reactor 11 where the cracking operation takes place. Thus, the gas phase advantageously present within the device from the exit of the reactor 11 to the filter 10 is referred to as the exit gas 3.

[0131] It is noted that within the scope of the present invention, the term "carbon product" 4 includes the solid phase produced by the cracking operation within the reactor 11. Thus, it is preferred to generate the carbon product 4 and then separate it from the gas phase in the separation step carried out in the separator 9.

[0132] Furthermore, it is noted that within the scope of the present invention, the term "purified exit gas" 6 includes the exit gas 3 that may have been filtered within the filter 10. Thus, the purified exit gas 6 should be considered as a gas mixture optimized in terms of its hydrogen content with respect to the exit gas 3.

[0133] It is noted that within the scope of the present invention, the term "reactor" 11 includes the element of the device in which the cracking operation takes place. The reactor 11 is understood to mean any element capable of allowing hydrocarbon cracking, preferably under the action of a carrier gas converted into a plasma.

[0134] The "inlet compressor" 7 will be understood to mean any device that advantageously allows the pressure of the inlet gas 1 to rise from the intake pressure p1 to the injection pressure p2.

[0135] It is noted that within the scope of the present invention, the term "exit compressor" 8 includes any device that allows the pressure of the exit gas 6 to rise from the delivery pressure p3 to the operating pressure p4.

[0136] It is noted that within the scope of the present invention, the term "separator" 9 includes any device element for separating the gas phase including the exit gas 3 from the solid phase including, for example, the carbon product 4 at the exit of the reactor 11.

[0137] It is noted that within the scope of the present invention, the term "filter" 10 includes any element of the device for purifying the exit gas 3 into hydrogen.

[0138] Within the scope of the present invention, the term "electrode" 5 includes any conductive element that can capture or release electrons within the device.

[0139] The term "storage element" 15 should be understood to mean any element for containing, preserving or enclosing the exit gas 3 or the purified exit gas 6 at the end of the process.

[0140] The term "plasma torch" includes any element that can advantageously partially ionize a gas by blowing a gas, for example, by a very energy-intensive electric arc.

[0141] The term "plasma torch" may also include an inductively coupled plasma torch.

[0142] It is noted that within the scope of the present invention, according to one embodiment, the term "inlet pressure p1" relates to the pressure at which a gas is introduced into the device.

[0143] It is noted that within the scope of the present invention, according to one embodiment, the term "injection pressure p2" relates to the pressure at which inlet gas 1 is injected into reactor 11.

[0144] It is noted that within the scope of the present invention, according to one embodiment, the term "delivery pressure p3" relates to the pressure at which outlet gas 3 is delivered at the outlet of reactor 11.

[0145] It is noted that within the scope of the present invention, according to one embodiment, the term "operating pressure p4" relates to the pressure at which outlet gas 3 is stored within storage element 15.

[0146] The present invention relates to a device for converting gaseous hydrocarbons into gaseous hydrogen. This conversion is characterized by no expansion in the gas phase, in other words, there is no expansion from the incoming reactants to the outgoing products.

[0147] According to one possibility, the absence of expansion is the result of the tightness in the partial conversion pipeline, particularly at reactor 11 where cracking occurs, and subsequently in the dihydrogen delivery pipeline 14. Thus, the injection pressure p2 is preserved. The terms "no expansion", "no pressure loss", and "tight" are understood to be able to allow a slight pressure drop (up to 20%) or some leakage, which is due to, for example, the tightness limitations of certain connections, or the area where the active electrode of the plasma torch 12 passes through the wall of reactor 11. These slight pressure drops may also occur due to the inevitable head losses in separator 9 or filter 10.

[0148] According to one embodiment, the injection pressure p2 may be slightly different from the delivery pressure p3 such that p2 is higher than p3.

[0149] In fact, in order for inlet gas 1 to penetrate reactor 11 optimally, inlet gas 1 may preferably need to be adjusted to an injection pressure p2 that is higher than the pressure present within reactor 11.

[0150] Generally, the terms "no expansion" or "no pressure loss" may, in practice, allow slight expansion, but with a pressure drop not exceeding 20% relative to the injection pressure p2.

[0151] Therefore, it is appropriate to focus on gas pressure rather than solid elements.

[0152] Within the scope of the present invention, the inlet gas 1 enters at an inlet pressure p1 and is then preferably pressurized in an inlet compressor 7, which is understood to be any device for raising the gas pressure. The inlet compressor 7 can advantageously be mechanical or hydraulic.

[0153] The inlet gas 1 leaves the inlet compressor 7 at an injection pressure p2 that is higher than the inlet pressure p1.

[0154] The inlet gas 1 comprises and preferably consists of hydrocarbons that undergo a cracking operation under pressure in the reactor 11.

[0155] The inlet gas 1 is injected into the reactor 11 at the injection pressure p2.

[0156] The injection can be via a plurality of openings into the reactor 11 and through injection holes that are oriented in different and radial directions with respect to the direction of the carrier gas flow 2 in the reactor 11.

[0157] Thus, the integrated annular injection at the reactor 11 ensures better penetration of CH4 or other inlet gas 1 into the plasma phase, where the viscosity can be higher than that of the cold gas.

[0158] Optionally, the operation may require sufficient injection kinetic energy to allow the plasma to penetrate into the reactor 11 and condition the mixture between the hydrocarbons and the carrier gas 2 in the plasma state.

[0159] In fact, at high pressure, the viscosity of the gas increases, which makes it more difficult to homogenize the mixture. The annular injection mainly makes it possible to improve the structure of the flow and thus control the turbulence therein, especially if the injection holes are axially symmetric.

[0160] Thus, according to one embodiment, a hydrocarbon cracking method is carried out by means of a plasma torch 12 equipped with a continuous electrode supply system 5.

[0161] In particular, the device can be equipped with electrode supply means outside the reactor 11.

[0162] The latter can include a magazine for storing a plurality of spare electrodes 5 awaiting use. In this embodiment, the supply means also has means for lowering the active electrode from outside the reactor 11 such that the active electrode dips into the internal volume of the reactor 11 and gradually descends as it wears. When it is almost worn out, the active electrode is replaced by one of the spare electrodes.

[0163] This replacement can be done by connecting the outer end of the active electrode to the lower end of the spare electrode, thus forming a continuous assembly, and the spare electrode ultimately replaces the active electrode during its downward movement in the reactor 11.

[0164] The cracking operation is carried out in the reactor 11 without pressure loss, so that the injection pressure p2 is maintained at the maximum value by the tightness of the device.

[0165] According to one embodiment, the cracking operation is carried out using a three-phase plasma torch technique 12, and a mixture of hydrogen and hydrocarbons is used as the carrier gas 2 for heat supply.

[0166] According to an example, for a production capacity of 12 kg / h, it will be necessary to supply the device with approximately 120 kW of power.

[0167] According to an example, for the operation of the plasma torch at 1 bar, a voltage supply of 500 V and a current supply of 150 A should be provided.

[0168] In one example, for the operation of the plasma torch at 20 bar, a voltage supply of 1500 V and a current supply of 50 A should be provided.

[0169] Therefore, the plasma cracking operation allows, for example, the separation of the outlet gas 3 and the solid carbon product 4 within a heterogeneous mixture.

[0170] A heterogeneous mixture is produced and then advantageously undergoes a separation step in the separator 9, where the outlet gas 3 and the carbon product 4 are separated. This separation can be achieved by gravity.

[0171] Therefore, for example, the solid carbon product 4 or the outlet gas 3 can be recovered, and the outlet gas 3 consists of a gas mixture including hydrogen and hydrocarbon residues, and if the latter is not complete, hydrocarbon residues may remain after the cracking operation.

[0172] According to an example, after the phase decomposition step, a partial gas mixture including and usually including residues of hydrogen and un-cracked hydrocarbons is used as at least a part of the carrier gas 2 of the plasma torch, and its circulation in the reactor 11 generates plasma. This partial gas mixture can be advantageously mixed with, for example, CH4.

[0173] In fact, the recirculation of the outlet gas 3 as the carrier gas 2 for the plasma can enable:

[0174] - Avoid using other carrier gases, such as nitrogen or air, which can prevent, for example, hydrogen contamination or the generation of HCN;

[0175] - Recover part of the energy contained in the reaction gas, for the purpose of energy optimization;

[0176] - Crack part of the hydrocarbons within the discharge area of the cracking plasma torch 12, and thus improve the cracking efficiency.

[0177] During the above steps, and according to one embodiment, graphitization of carbon can occur, i.e., the carbon advantageously dissociated by the cracking operation precipitates in a graphite state, in particular due to an increase in the pressure of the device, where the reactants are circulated and undergo transformation in the device.

[0178] According to a particular embodiment, the manufacturing device includes a pumping system 16 on the recirculation line downstream of the reactor 11, and the pumping system 16 is configured to redirect a portion of the mixture of hydrocarbons and hydrogen from the outlet of the reactor 11 to the carrier gas injection line. This compensates for the head loss due to the filtration system. In fact, the reinjection of a portion of the gas generated in the torch requires a pressure equal to or slightly higher than the pressure of the main injection line.

[0179] According to a particular embodiment, the recirculation line for the mixture of hydrocarbons and hydrogen at the outlet of the reactor 11 is configured to direct the mixture at least partially into the plasma torch 12 and / or at least partially within the reactor 11.

[0180] Preferably, as Figure 2 shown, the device includes at least one first regulating device 17a, which includes a regulating valve at the intersection at the outlet of the reactor 11 located between the recirculation line and the line leading to the filter 10. The first regulating device 17a allows the regulation of the proportion of the gas mixture suitable for recirculation to be used as the carrier gas 2. The device includes at least one computing unit, which is capable of communicating with at least one regulating valve and is configured to analyze the data of the said mixture and allow servo-control of the regulation. In this way, the device allows the proportional regulation of the amounts of the elements constituting the circulating gas mixture, thereby optimizing the efficiency of the device 7.

[0181] Preferably, the first regulating device is configured to regulate the proportion of methane (CH4) in the carrier gas 2.

[0182] According to a particular embodiment, Figure 1 and Figure 2 all the pipelines shown in the device in

[0183] The carbon product 4 obtained can be stored in a container for subsequent recovery and use.

[0184] Regarding the outlet gas 3, it will be recycled from the separation step to the filtration step, which will make it possible to separate hydrogen from the uncracked hydrocarbons.

[0185] Thus, the filter 10, which is understood to be any element for filtering the outlet gas 3, is capable of converting the outlet gas 3 into a purified outlet gas 6. The latter advantageously contains only hydrogen, for example, at a purity level exceeding 99%.

[0186] According to one embodiment, at the outlet of the filter 10, two gas phases can be distinguished:

[0187] - The purified outlet gas 6;

[0188] - A gas mixture composed of un-cracked hydrocarbons and hydrogen at the delivery pressure p3;

[0189] According to one embodiment, the purified outlet gas 6 consists essentially of dihydrogen at the delivery pressure p3.

[0190] According to one embodiment, the purified outlet gas 6 can be further pressurized from the delivery pressure p3 to the operating pressure p4.

[0191] In fact, the outlet compressor 8 preferably allows the pressure of the purified outlet gas 6 to rise from the delivery pressure p3 to the operating pressure p4.

[0192] Thus, the purified outlet gas 6 is contained, for example, at the operating pressure p4 at the outlet of the device, within the storage element.

[0193] Thus, generally:

[0194] - The injection pressure p2 is greater than or equal to the intake pressure p1. For example, it can be at least four times higher.

[0195] - The delivery pressure p3 is greater than or equal to the injection pressure p2.

[0196] - The operating pressure p4 is greater than or equal to the delivery pressure p3. For example, it can be at least ten times higher. Further or alternatively, the operating pressure p4 can be higher than 200 bar or even 300 bar.

[0197] Thus, according to this embodiment, throughout the dihydrogen production step, the method is carried out without expansion of the gas phase.

[0198] According to one embodiment, at the delivery pressure p3, a partial gas mixture composed of hydrocarbons and hydrogen produced by the filtration step is reintroduced at the inlet of the reactor 11.

[0199] This allows the hydrocarbons to be recycled in the device and thus optimizes the efficiency of the device.

[0200] The reinjection of hydrocarbons can be carried out before or after the upstream compressor of the facility (if any). Preferably, the reinjection of hydrocarbons can be carried out in the carrier gas.

[0201] According to a particular embodiment, the separator 9 for separating the outlet gas 3 downstream of the reactor 11 from the carbon product 4 comprises or even is a filter, preferably a buffer filter, which comprises a vacuum-sealed flange connection and has an electropolished surface, for better handling at the nanoscale (10-9 -10 -7 an element of (-10 m). Further, according to the same embodiment, the separator 9 is configured to withstand a temperature of at least 200 °C. Thus, the filtration system allows continuous operation, preferably with the possibility of recovering toner without shutting down with an air lock system.

[0202] According to a particular embodiment, the device includes a heat exchanger 15 upstream of the separator 9 and downstream of the reactor 11. The heat exchanger 15 can be a gas-gas exchanger, where the fresh gas can be at least a portion of the inlet gas 1 and / or at least a portion of the gas leaving the inlet compressor 7. Thus, the heat exchanger 15 allows the inlet gas 1 to recover at least partially the heat from the gas mixture leaving the reactor 11.

[0203] In fact, this allows the temperature of the gas mixture leaving the reactor 11 to be reduced before it enters the separator 9, thus avoiding damage to the device, regardless of the reaction yield in the reactor 11. In addition, the heat exchanger 15 improves the energy efficiency of the method by recovering part of the waste heat from the gas mixture leaving the reactor 11 and transferring it to the inlet gas 1 which may initially be at ambient temperature. The heat exchanger 15 is configured not to cause a pressure drop greater than or equal to 20%.

[0204] According to one embodiment, for a dihydrogen production capacity from 8 kg / h to 16 kg / h of methane, the device needs to be supplied with a power of approximately 80 to 160 kW. This production capacity corresponds to a mass flow rate of methane (CH4) of approximately 30 to 70 kg / h. The flexibility of the plasma cracking operation allows it to operate at a lower power level, i.e., at least 20% of the plasma power, which corresponds to a minimum methane flow rate of 10 kg / h, equivalent to 15 Nm3 / h.

[0205] According to one embodiment, the dihydrogen production capacity can be multiplied by a factor, for example multiplied by 10 or multiplied by 100, and all equipment can be scaled, and this scaling of the production capacity does not have to be linear with the scaling of the facility size. Advantageously, all flow rates and / or power values can be adapted accordingly and proportionally to the production capacity.

[0206] According to a particular embodiment, at the outlet of the separator 9, at the level of the recirculation line of the gas mixture towards the reactor 11, approximately 50% of the gas mixture containing a high percentage of hydrogen can be recirculated towards the reactor 11.

[0207] In addition, the device is configured to allow a hydrocarbon stream, preferably methane (CH4), to be supplied to said recirculation line or the plasma torch 12.

[0208] According to a particular embodiment, the entire carrier gas 2 includes at least a portion of the inlet gas 1 and / or at least a portion of the outlet gas 3.

[0209] Preferably, the entire carrier gas 2 only includes part of the inlet gas 1 and / or part of the outlet gas 3.

[0210] The flow rate from the inlet gas 1 is preferably between 8 kg / h and 16 kg / h, preferably between 10 kg / h and 14 kg / h and preferably up to 12 kg / h, and advantageously undergoes compression in the compressor 7. This additional methane flow enables the temperature of the plasma gas or carrier gas to be reduced at the same power. For example, at the same temperature and volumetric flow rate, methane has a higher volumetric heat capacity than hydrogen and can therefore contain more energy.

[0211] The present invention is not limited to the previously described embodiments and extends to all embodiments covered by the claims.

[0212] List of reference numerals

[0213] 1. Inlet gas

[0214] 2. Carrier gas

[0215] 3. Outlet gas

[0216] 4. Carbon product

[0217] 5. Electrode

[0218] 6. Purified outlet gas

[0219] 7. Inlet compressor

[0220] 8. Outlet compressor

[0221] 9. Separator

[0222] 10. Filter

[0223] 11. Reactor

[0224] 12. Plasma torch

[0225] 13. Injection line

[0226] 14. Delivery line

[0227] 15. Heat exchanger

[0228] 16. Pumping system

[0229] 17a. First regulating device

[0230] 17b. Second regulating device

[0231] 15. Storage element

[0232] p1. Inlet pressure

[0233] p2. Injection pressure

[0234] p3. Delivery pressure

[0235] p4. Operating pressure.

Claims

1. A method for producing a hydrogen-containing exit gas (3), comprising injecting a hydrocarbon inlet gas (1) into a reactor (11) having a plasma torch (12), operating to crack the inlet gas (1) with the plasma torch (12), and then delivering the exit gas (3), characterized in that From injecting the inlet gas (1) into the reactor (11) to delivering the outlet gas (3) for the manufacturing, while neither the inlet gas (1) nor the outlet gas (3) undergoes an expansion greater than 20%, supplying the plasma torch (12) with three-phase current, and cracking the inlet gas (1) with plasma, the carrier gas (2) of the plasma being a mixture comprising hydrogen and / or hydrocarbons, the method comprising at least one separation operation carried out downstream of the cracking operation to separate the outlet gas (3) from the solid carbon product (4), and downstream of the separation operation, using a portion of the outlet gas (3) in the carrier gas (2).

2. The method according to claim 1, wherein, The injection of the inlet gas (1) is carried out at an injection pressure (p2) greater than or equal to 4 bar.

3. The method according to claim 1, comprising compressing upstream of the injection into the reactor (11) to the injection pressure (p2).

4. The method according to claim 1, comprising a filtration operation carried out downstream of the separation operation to produce a purified outlet gas (6) having a higher dihydrogen concentration than the outlet gas (3).

5. The method according to claim 4, wherein, The purified outlet gas (6) is stored at an operating pressure (p4) greater than or equal to the injection pressure (p2).

6. The method according to claim 5, wherein, The purified outlet gas (6) is stored at an operating pressure (p4) strictly higher than the injection pressure (p2).

7. The method according to claim 4, wherein, In addition to the purified outlet gas (6), the filtration operation produces a hydrocarbon gas, which is reinjected into the reactor (11).

8. The method according to claim 1, wherein, The inlet gas (1) is CH4.

9. The method according to claim 8, wherein The portion of the outlet gas (3) used in the carrier gas (2) comprises CH4.

10. The method according to claim 1, wherein Using a plasma torch (12), without stopping the manufacturing of the outlet gas (3), the plasma torch (12) is continuously supplied with electrodes (5) to prevent pressure variations within the reactor (11).

11. An apparatus for manufacturing an outlet gas (3) containing dihydrogen, comprising an injection line (13) for injecting a hydrocarbon inlet gas (1) into a reactor (11), the reactor (11) comprising a plasma torch (12) configured to produce a cracking operation of the inlet gas (1) and a delivery line (14) for the outlet gas (3), the apparatus being configured such that the inlet gas (1) is transformed from its injection into the reactor (11) until its return as the outlet gas (3) without undergoing an expansion greater than 20%, the plasma torch (12) being supplied with three-phase current, and the apparatus being configured such that the cracking of the inlet gas (1) is carried out with plasma, the carrier gas (2) of the plasma being a mixture comprising hydrogen and / or hydrocarbons, the apparatus comprising a separator (9), the separator (9) being located downstream of the reactor (11) and being configured to allow the separation of the gas mixture at the outlet of the reactor (11) into an outlet gas (3) and a solid carbon product (4), and such that a portion of the outlet gas (3) is reinjected into the carrier gas (2).

12. The device according to claim 11, wherein, The injection line (13) includes a plurality of injection holes, which are oriented in different and radial directions with respect to the flow direction of the carrier gas (2) in the reactor (11).

13. The device according to claim 11, including an inlet compressor (7) of the inlet gas (1) placed on the injection line (13).

14. The apparatus according to claim 11, wherein, The plasma torch (12) includes an electrode (5), and the electrode (5) is configured to be continuously supplied and prevent pressure changes within the reactor (11).

15. The device according to any one of claims 11 to 14, wherein the device prevents pressure changes from the injection line (13) into the reactor (11) until it returns from the outlet gas (3).

16. The device according to any one of claims 11 to 14, including an outlet compressor (8) downstream or upstream of the storage element, configured to raise the pressure of the outlet gas (3) from the delivery pressure (p3) to the operating pressure (p4).

17. The device according to any one of claims 11 to 14, including a pumping system (16) on the recirculation line of a portion of the outlet gas (3).

18. The device according to any one of claims 11 to 14, including a heat exchanger upstream of the separator (9) and downstream of the reactor (11).

19. The device according to claim 18, wherein, The heat exchanger is a gas-gas exchanger, wherein the fresh gas is at least a portion of the inlet gas (1).

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