Pyrolysis reactor for pyrolysis of hydrocarbons and related pyrolysis plant and process for pyrolysis of hydrocarbons
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- I-H2 SRL
- Filing Date
- 2024-07-17
- Publication Date
- 2026-05-27
AI Technical Summary
The process of pyrolysis of hydrocarbon gases results in carbon byproducts that can clog reactor access areas, hinder catalyst operation, and complicate hydrogen gas separation, necessitating the use of additional inert gas facilities which increase costs and complexity.
A pyrolysis reactor and process featuring a furnace with a heating chamber and reaction tubular structures arranged such that hydrocarbons are fed from top to bottom and hydrogen is removed from bottom to top, creating a communication zone at the bottom where carbon can fall by gravity, facilitating its removal without the need for additional inert gas facilities.
This configuration maximizes gravity separation of carbon, preventing clogging and ensuring proper operation of catalysts and hydrogen separation, thereby simplifying the system and reducing costs compared to traditional methods.
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Figure IB2024056931_23012025_PF_FP_ABST
Abstract
Description
[0001] PYROLYSIS REACTOR FOR PYROLYSIS OF HYDROCARBONS AND RELATED PYROLYSIS PLANT AND PROCESS FOR PYROLYSIS OF HYDROCARBONS
[0002] The present invention relates, in general, to a pyrolysis reactor for pyrolysis of hydrocarbons, a pyrolysis plant including said reactor, and a respective pyrolysis process.
[0003] The process of pyrolysis of gaseous hydrocarbons, particularly propane (or LPG- Liquified Petroleum Gas) and methane (or natural gas), is accomplished by heating the gases, which involves their thermal splitting according to the following reactions: CH4C + 2H2for methane with energy absorption of 75.6kJ / mol
[0004] C3HS-> 3C + 4H2for propane with energy absorption of 119.5kJ / mol and, more generally, for other related hydrocarbons according to the reaction:
[0005] Cn / 72n+2-> nC + (n + 1) / V2for gaseous paraffins.
[0006] (T. Muto, M. Asahara, T. Miyasaka, K. Asato, T. Uehara, M. Koshi, Methane pyrolysis characteristics for the practical application of hydrogen production system using permalloy plate catalyst, Chemical Engineering Science (2022), doi: https: / / doi.Org / 10.1016 / j.ces.2O22.117931
[0007] Markova, E.B. Cherednichenko, A.G.; Smirnova, S.S.; Sheshko, T.F.; Kryuchkova, T.A. Features of the Catalytic Cracking of Propane with a Step- Wise Change PrxYb2xZr2O7. Catalysts 2023, 13, 396. htps; / / doi.org / 10.3390 / catal13020396)
[0008] The process of pyrolysis of hydrocarbon gases yields two materials:
[0009] • Solid carbon in the form of crystalline graphite, also with the presence of nanostructured allotropic forms: carbon nanotubes, graphene, fullerene;
[0010] • hydrogen gas.
[0011] The pyrolysis process can be carried out in a furnace or reactor that can be empty or filled with inert or catalytically active material (catalytic pyrolysis).
[0012] In such pyrolysis processes, the problem of dealing with carbon that is formed as a byproduct in the decomposition of organic materials is well known and can affect the structure and operation of the reaction furnace. In fact, carbon can result in clogging of access areas of the reactor, prevent proper operation of the catalysts, or prevent proper separation of the hydrogen gas that is formed. To overcome this problem, it is often necessary to operate at low partial pressure, either by resorting to vacuum or by using an inert gas such as CO2 or N2 as a diluent. However, this solution requires the installation of additional inert gas facilities that complicate the system and have additional costs.
[0013] SUMMARY OF THE INVENTION
[0014] The technical problem posed and solved by the present invention is to develop a pyrolysis reactor, a pyrolysis plant and a respective pyrolysis process that are configured and structured to facilitate a carbon removal.
[0015] This problem is solved by a pyrolysis reactor, a pyrolysis plant and a respective pyrolysis process as defined in the respective independent claims. Secondary or optional features of the invention are defined in the respective dependent claims.
[0016] In practice, a pyrolysis reactor is provided for pyrolysis of hydrocarbons with hydrogen and carbon formation, in which the pyrolysis reactor includes a furnace having a heating chamber. The heating chamber has at least one bottom zone. The pyrolysis reactor further includes at least one reaction tubular structure intended to allow a pyrolysis reaction, wherein the reaction tubular structure is arranged at least partially in the heating chamber and is connected with an area outside the heating chamber to allow a hydrocarbon input and a hydrogen output.
[0017] According to one aspect of the present disclosure, the reaction tube structure includes at least a first conduit and a second conduit both extending from top to bottom, i.e. , from a superior zone to a inferior zone, or again from a top zone to a bottom zone, or vice versa, wherein the one between the first conduit and the second conduit is intended to conduct at least one hydrocarbon input, and the other between the first conduit and the second conduit is intended to conduct, at least in part, a hydrogen output. As a result, hydrocarbons can be fed in a kind of downward conduit, and hydrogen is let out in a kind of upward conduit. According to the present disclosure, a connecting zone between such conduits is a lower zone or bottom zone than at least a remaining part of the first conduit and a remaining part of the second conduit.
[0018] It is understood that, according to this disclosure, said first conduit and said second conduit have at least partially a configuration such that the connecting zone is, with respect to a direction of the fluids, a valley bottom zone.
[0019] As a result, according to this disclosure, the first conduit is in fluid communication with the second conduit via a communication zone, which is in a bottom zone, or lower zone, than a hydrocarbon supply zone and lower, or lower zone, than a hydrogen outlet or outflow zone from the heating chamber. In other words, one can identify in the path of hydrocarbon input, and hydrogen output obtained from pyrolysis, a zone of lowest height or lowest of all, where carbon can fall by gravity.
[0020] In still other words, the first conduit and the second conduit are arranged so that the hydrocarbon input is from top to bottom, and the hydrogen output is from bottom to top. As a result, a connection zone or fluid communication zone between the first duct and the second duct is located in a low area of the furnace, i.e. , toward a bottom zone, so that the gravity fall of carbon is facilitated. There is the advantage that it is not even necessary to control where the carbon is formed specifically, since due to the geometry of the parts described above, gravity fall can occur from the first duct as well as from the second duct.
[0021] It follows that the communication zone between the first duct and the second duct is preferably configured and intended to receive carbon produced by pyrolysis at least by gravity. In this way, the communication zone between the ducts is also configured as a zone for collecting, possibly temporary, carbon.
[0022] It can be understood that the leakage of hydrogen through the intermediate space is in fact a leakage through the second conduit.
[0023] According to a preferred aspect, the reactor includes means of vibration to vibrate said first conduit and / or said second conduit, and further facilitate the fall of carbon by gravity downward.
[0024] Preferably, one or the other between the first duct and the second duct is an inner duct arranged inside the other between the first duct and the second duct serving as the outer duct, defining an intermediate space interposed between the inner duct and the outer duct. In this case, one inlet of the inner duct is open and facing the bottom area of the furnace and is surrounded by said outer duct. The open inlet places the inner duct in fluid communication with said intermediate space, so as to define said communication zone and create a circuit of fluid passing from the inner duct to the intermediate space passing through the inlet of the inner duct. This structure of ducts one inside the other allows for the optimization of space within the heating chamber, and to create the movement of fluid from top to bottom and bottom to top for carbon drop, and at the same time with unhindered duct communication in the fluid conduction. To facilitate the desired fluid movement, the inner duct and outer duct can be made of gas impermeable material, especially impermeable to hydrogen and hydrocarbon-containing fluid, such as stainless steel, so that the gas flow can be unidirectional. In other words, and without wishing to be bound by any theory, the reactor configuration of concentric ducts (or one-inside-the-other duct structure) allows for the occurrence of a pressure difference (or pressure delta) that promotes unidirectional flow, i.e., a fluid circuit passing from the inner duct to the intermediate space through the communication zone if the hydrocarbon fluid input occurs from the top of the inner duct or a fluid circuit passing from the intermediate space to the inner duct through the communication zone if the hydrocarbon fluid input occurs from the top of the outer duct or top of the intermediate space.
[0025] As explained, said inlet fluid basically includes hydrocarbons that descend the first conduit (i.e., the conduit from which they are fed) while the outlet fluid basically includes hydrogen obtained from the pyrolysis reaction that ascends the second conduit. This also occurs because methane has a higher density than hydrogen and therefore once it is fed into one of the two conduits it will tend to descend the conduit (from top to bottom) unlike hydrogen which indeed having lower density will ascend the second conduit from bottom to top also favouring the fall or collection of carbon formed by pyrolysis in a connection or communication zone located at the bottom or downstream of the two conduits. In addition, the duct structure one inside the other allows for better management of the heating process of the hydrocarbon being thermally split; in fact, for example, simultaneous heating takes place in the same area of the two ducts.
[0026] The configuration in which one conduit is placed inside the other is a configuration that can be understood to be concentric conduits, but without limiting understanding that the centres of the conduits must coincide.
[0027] In case the material from which the tubes are made is also metal useful for catalytic pyrolysis, the concentric tube configuration allows for an increase per unit length of the reactor in the surfaces over which the hydrocarbon splitting reaction is catalyzed compared to the configuration that does not involve two tubes one inside the other; in fact, the outer surface of the inner tube can also be exploited in the upflow phase.
[0028] Preferably, the outer duct is insulated with respect to the heating chamber to close said communication zone and form a closed chamber, said closed chamber thus including or enclosing said communication zone and being closed with respect to the heating chamber. In this form of construction, the mouth of the inner duct is open to said closed chamber. This conformation has the advantage that the same outer duct can be used as a carbon collection zone. Preferably, the outer duct engages, i.e., is fixed, in a back wall of the furnace, so that the furnace walls are also exploited for the realization of the closed, carbon-collecting chamber. Even more preferably, the inner duct and the outer duct are attached on one side to a kiln wall, such as a kiln top wall. This solution has the advantage of further exploiting the furnace for duct support.
[0029] Preferably, it is the inner conduit intended to allow hydrocarbon input, and said intermediate space is intended to allow a hydrogen outflow. This makes it possible to optimize, through careful choice of duct sizes, hydrocarbon flow rates and increase the reaction yield as much as possible.
[0030] Preferably, the inner conduit and outer conduit are tubes of circular cross section to allow homogeneous pyrolysis over the entire circumference and an evenly distributed carbon drop at the bottom.
[0031] To facilitate carbon drop, the inner duct and outer duct are arranged vertically in the heating chamber.
[0032] Still preferably, the reactor includes metal catalysts at least on the inner conduit, i.e. , the inner conduit is made of a metal material where the metals in the material are metal catalysts. This embodiment allows the conduit where hydrocarbons pass through to also be used to catalyze the pyrolysis reaction.
[0033] Preferably, still to heat the ducts evenly, the reactor includes heaters arranged on side walls facing the heating chamber.
[0034] The present disclosure also preferably relates to a pyrolysis plant including a pyrolysis reactor as previously described, and a removal apparatus, for removing carbon formed in the communication zone between the two ducts. Such a removal apparatus is configured to be placed in communication, preferably as needed, with the communication zone between the first conduit and the second conduit to allow carbon to be removed. Preferably, such removal apparatus further takes advantage of gravity, and is arranged below a back wall of the furnace.
[0035] For example, the carbon removal apparatus can be put in fluid communication with the open mouth of the inner duct by a passage or door made in the back wall of the furnace. Such a passage or door can be opened if necessary with a valve, or shut-off leaf, which is removed or operated to open the door or passage (opening).
[0036] The removal apparatus may include a box structure defining a collection chamber intended for the collection of carbon, falling through said door or passage or opening. Such a box structure allows at least temporary collection of carbon. Oxygen is preferably removed in the collection chamber to prevent the carbon from burning.
[0037] Preferably said door or opening or passageway is a first opening, and the removal apparatus includes a second door or second opening in a back wall of the collection chamber provided with respective selectively operable closing leaf for a final removal of carbon from the pyrolysis plant.
[0038] This disclosure also covers a pyrolysis process for pyrolysis of hydrocarbons and formation of hydrogen and carbon, wherein the process comprises:
[0039] - Arranging at least one first duct in a pyrolysis heating chamber so that said first duct is affected by a top-down oriented flow or the first duct is top-down oriented;
[0040] - Arranging at least a second duct in the heating chamber so that said second duct is affected by a flow oriented from the bottom to the top or the second duct is oriented from the bottom to the top;
[0041] - connecting said first conduit with said second conduit, so that a communication zone of said first conduit with said second conduit is in a bottom zone or lower than respective to remaining parts of the first conduit and the second conduit;
[0042] - Entering hydrocarbons through the first conduit;
[0043] - determining a thermal splitting of hydrocarbons along at least the first conduit;
[0044] - Leaking hydrogen into the second conduit;
[0045] - Dropping by gravity toward said communication zone at least some of the carbon produced by pyrolysis.
[0046] As mentioned main advantage of the present disclosure concerns precisely the possibility of maximizing a gravity separation of the carbon produced in the pyrolysis process.
[0047] The process can be carried out through a pyrolysis reactor and / or the pyrolysis plant as described above, taking advantage of all the respective benefits stemming therefrom. Other advantages, features and ways of using the subject invention will be evident from the following detailed description of some embodiments, presented for illustrative and non-limiting purposes.
[0048] BRIEF DESCRIPTION OF THE FIGURES
[0049] The present invention and the following detailed description of the preferred embodiments can be better understood by reference to the figures below:
[0050] Figure 1 shows a schematic view from one side of a reactor of a pyrolysis plant according to an embodiment;
[0051] Figure 2 shows a schematic top view of the reactor in Figure 1 ;
[0052] Figure 3 shows a schematic view from one side of a pyrolysis plant according to an embodiment and in an early operational phase;
[0053] Figure 4 shows a schematic view from one side of the pyrolysis plant in Figure 3 in a second operational phase; Figure 5 shows a schematic view from one side of the Figure 3 pyrolysis plant in a third operational phase.
[0054] DETAILED DESCRIPTION OF THE INVENTION
[0055] With reference to the figures, a pyrolysis reactor 10 of a pyrolysis plant 100 for pyrolysis of hydrocarbons is described. Pyrolysis reactor 10 is to be understood as a portion of pyrolysis plant 100 intended for hydrocarbon splitting. The pyrolysis plant 100 also includes areas for collecting and handling hydrogen that is produced and carbon C as a pyrolysis by-product, and additional devices and equipment of known types for controlling and operating the pyrolysis plant.
[0056] More specifically, pyrolysis plant 100 with its respective pyrolysis reactor 10 is shown in schematic form to show the main components of pyrolysis plant 100 and its reactor 10, with the understanding that the remaining parts of the reactor may be optimized according to the expertise of the person skilled in the art.
[0057] More specifically, the pyrolysis reactor comprises a furnace 12, i.e., a substantially enclosed structure, having a box shape.
[0058] The term "substantially enclosed structure" means a structure, which apart from openings or doors of communication with the outside is intended to define a delimited or circumscribed area of the furnace 12. Said circumscribed area is called a heating chamber 12a, that is, it is an area intended to be heated to enable the splitting of hydrocarbons. More particularly still, to define said substantially enclosed structure, the furnace includes containment walls, such as, for example, a side mantle wall 13, a back wall 14 and a top wall 15 defining the heating chamber 12a.
[0059] With reference to said walls, it can be understood that in heating chamber 12a, a top zone 15a, a bottom zone 14a, and side zones 13a can be identified, i.e., areas of the heating chamber that are close to or adjacent to the respective walls.
[0060] Furnace 12 also includes heaters 20, e.g., electric heaters 20, which are preferably mounted in heating chamber 12a to heat heating chamber 12a from side zone 13a. Preferably, the electric heaters are powered, for example, in a percentage fraction greater than 50% by electricity generated from renewable sources. It is to be understood that the choice of furnace materials and the heating capacity by the heating elements 20 are chosen according to the pyrolysis process to be achieved and are within the reach of the branch technician.
[0061] According to one aspect of the present disclosure, the reactor 10 comprises a tubular reaction structure including two reaction conduits. These are called reaction conduits because they enable pyrolysis and include at least one reaction conduit intended for hydrocarbon input and one reaction conduit intended for a hydrogen output.
[0062] According to one aspect of the present disclosure, the two reaction conduits are arranged so that hydrocarbons are fed from top to bottom in a first conduit and hydrogen is removed from bottom to top in the other conduit so that carbon C formed by pyrolysis can fall or be gravity-driven into a connecting or communicating zone between the two conduits.
[0063] In the case illustrated, the reaction ducts include an outer duct 25 and an inner duct 26, i.e., the inner duct is arranged within the outer duct to form or define an interspace or intermediate space 30 or gap between the two reaction ducts. In other words, the two reaction ducts are arranged to allow hydrocarbon input into one between the inner duct 26 and the intermediate space 30 or between the inner duct 26 and the outer duct 25, and hydrogen output from the other between the inner duct 26 and the intermediate space 30.
[0064] The outer duct 25 is preferably insulated from the heating chamber 12a to define a closed chamber 31 and an inner duct mouth 26 is open to said closed chamber and to the space in between. Closed chamber 31 means an isolated space with respect to heating chamber 12a. The closed chamber 31 with an open mouth defines a communication zone or connection zone between the two ducts and is intended to receive the carbon C formed after pyrolysis of the hydrocarbon (thermal splitting of hydrocarbons).
[0065] Accordingly, the present invention relates to a pyrolysis reactor (10) for pyrolysis of hydrocarbons and formation of hydrogen and carbon (C), wherein the pyrolysis reactor (10) includes a furnace(12) having a heating chamber (12a), wherein said heating chamber (12) has at least one bottom zone (14a) and wherein the pyrolysis reactor (10) includes at least one reaction tubular structure intended to allow a pyrolysis reaction, wherein said reaction tubular structure is arranged at least partially in the heating chamber (12a) and connected with an area outside the heating chamber (12a) to allow a hydrocarbon input and a hydrogen output, characterized in that the reaction tubular structure includes at least a first duct (25) and a second duct (26) oriented from a top zone (15a), or zone higher than the bottom zone, toward the bottom zone (14a), wherein the one between the first duct (25) and the second duct (26) is intended to conduct at least one hydrocarbon input and the other between the first duct (25) and the second duct (26) is intended to conduct at least one hydrogen leakage and wherein the first conduit (25) is in fluid communication with the second conduit via a communication zone (31), and wherein said communication zone (31) is arranged in a lower position, and / or in the bottom zone (14a), at least with respect to remaining parts of the first conduit (25) and the second conduit (26). More specifically, if the hydrocarbons to be split arrive in one between the inner conduit 26 and the intermediate space 30, as a result of pyrolysis, the hydrogen formed may flow into the other between the inner conduit 26 and the intermediate space 30.
[0066] To allow the passage of gas and in general fluid from one between the inner duct 26 and the intermediate space 30, and the other between the inner duct 26 and the intermediate space 30, the inner duct 26 has as said mouthpiece that feeds into the closed chamber 31 , and due to the geometry of the parts the mouthpiece of the inner duct 26 is arranged inside with respect to the closed mouthpiece (with respect to the heating chamber 31) of the outer duct 25.
[0067] As a result, any carbon C formed from pyrolysis of hydrocarbons in or near one between inner duct 26 and intermediate space 30, i.e., in the communication zone between inner duct 26 and outer duct, may fall, or be made to fall by gravity, for example to the bottom of the closed chamber 31.
[0068] In other words, a gravity separation of carbon C may be favoured.
[0069] In the solution shown, inner conduit 26 has a much larger cross-sectional area than the intermediate space 30; it follows that to optimize the pyrolysis process and make maximum use of hydrogen production, inner conduit 26 is intended to accommodate the hydrocarbon stream and the intermediate space 30 between inner conduit 26 and outer conduit 25 is intended to accommodate the hydrogen stream formed by pyrolysis.
[0070] It cannot be ruled out that by changing the relative shape and size between the inner duct and the intermediate space, hydrocarbons could flow into the gap and hydrogen could flow into the inner duct.
[0071] It is to be understood that hydrocarbon and possibly hydrogen flows are handled by special pumps located outside the heating chamber.
[0072] Preferably inner conduit 26 and outer conduit 25 are circular or square pipes.
[0073] The cross section of ducts is not intended to be limiting; the cross section may be noncircular. Ducts can be closed profiles, thus also polygonal in cross-section. What is important is that the tubular bodies have the duct function.
[0074] As an example, outer duct 25 can also be made with a conical profile, for example, with a larger passage span at the base than at the top.
[0075] In other words, the architecture of the system involves two concentric ducts (Figure 1 and Figure 2), where the term concentric means that the inner duct is inserted into the outer duct to form a gap. As anticipated above, the arrangement of two ducts one inside the other and the opening of the mouth of inner duct 26 allows for a communication zone between the two ducts and gravity separation of the carbon C that is produced in the pyrolysis process. For example, hydrocarbon flows into inner duct 26 and undergoes a preheating process. Then, as the inner tube is open to the closed chamber 31 , the hydrocarbon once escapes from the inner tube laps the bottom of the outer tube 25 and then rises into the gap between the outer tube 25 and the inner tube 26. During the described way, the hydrocarbon is thermally cleaved (pyrolyzed) by hydrocarbon cracking process. Solid carbon C is deposited on the duct walls and bottom of outer duct 25 while hydrogen flows to the upper section of outer duct 25 and is extracted by pyrolysis furnace 12.
[0076] Thus, the present invention also relates to a pyrolysis reactor (10) for pyrolysis of hydrocarbons and formation of hydrogen and carbon (C), in which the pyrolysis reactor (10) comprises:
[0077] - A furnace (12) having a heating chamber (12a), said heating chamber (12a) having at least one bottom zone (14a), and
[0078] - at least one tubular reaction structure designed to allow a pyrolysis reaction arranged at least partially in the heating chamber (12a) and connected with an area outside the heating chamber (12a) to allow a hydrocarbon input and a hydrogen output, the pyrolysis reactor being characterized by the fact that the reaction tubular structure includes at least a first duct (25) and at least a second duct (26) placed inside each other to define an intermediate space (30) interposed between the first inner duct (26) and the second outer duct (25) and oriented from a top zone (15a), or zone higher than the bottom zone, toward the bottom zone (14a) of the heating chamber (12a), wherein one between the first outer conduit (25) and the second inner conduit (26) is configured for hydrocarbon input and the other is configured for hydrogen output, wherein the first outer duct (25) is in fluid communication with the second inner duct (26) via a communication zone (31) arranged below and / or opposite the hydrocarbon input zone and / or in the bottom zone (14a) of the heating chamber, wherein an inlet of the inner duct (26) facing the bottom zone (14a) is surrounded by said outer duct (25) and places in fluid communication the inner duct (26) with said intermediate space (30) so as to define said communication zone (31) and create a circuit of fluid passing from the inner duct (26) to the intermediate space (30), or vice versa, through the inlet of the inner duct (26), said at least first conduit (25) and at least second conduit (26) being preferably made of gas-impermeable material such that said through-fluid circuit is unidirectional. The wording "unidirectional flow" also means that no hydrogen backflow or countercurrent hydrogen leakage will occur in the reactor. In other words, in the reactor according to any of the described embodiments, hydrogen will not flow up the conduit into which hydrocarbons are fed. For example, the incoming flow of hydrocarbons will always be in the same direction and the outgoing flow of hydrogen is always in the same direction, such as from bottom to top.
[0079] According to an embodiment form of the invention, said inner conduit (26) is intended to allow hydrocarbon input and said intermediate space (30) is intended to allow a hydrogen output. According to an alternative embodiment of the invention, said intermediate space (30) is intended to allow hydrocarbon input and said inner conduit (26) is intended to allow a hydrogen output.
[0080] For communication of inner duct 26 and outer duct 25 with the outside, fittings or connecting ducts of a known type are preferably arranged outside the top wall 15. Inner duct 26 and outer duct 25 pass through the top wall 15 for connection with connecting ducts respectively.
[0081] Preferably, inner conduit 26 and outer conduit 25 are arranged vertically in the heating chamber to optimize the carbon C drop. Preferably, the heating elements 20 are arranged in a position to allow proper radiation of the ducts within which the hydrocarbons and hydrogen flow.
[0082] Preferably, the activation energy for the thermal splitting process can be decreased through the use of catalysts. For example, metal catalysts based on Fe-Ni, Fe-Ni-Cr, Fe- Ni-Cr-Mo, Fe-Ni-Cr-W, Ni-Cr, Ni-Cr-Mo, Ni-Co, Fe-Co-Co, Fe-Ni-Co-Co also made using commercial alloys (stainless steels containing Ni, e.g., 1.4310, 1.4301 , 1.4305, 1.4307, 1.4567, 1.4845, 1.4841 , 1.4401 , 1.4404, 1.4578, 1.4571 , 1.4598, 1.4541 , 1.4542) or Nickel superalloys, (e.g. Nimonic series, Permalloy series, Inconel of 600 series, 700 series, 800 series, Hastelloy series, Incoloy series) or cobalt alloys (e.g. Stellite series, IIMCO series).
[0083] The catalysts are preferably said materials described in the previous paragraph, it is not necessary to have the specific catalysts, but the alloys of the pipes themselves can be the catalysts.
[0084] The use of catalysts makes it possible to decrease the temperature at which the process of thermal splitting of hydrocarbons takes place. Preferably, the present invention for pyrolysis of hydrocarbons covers the thermal operation of pyrolysis furnaces from 550°C to 1200°C. The temperature of the furnace 12 is measured by one or more thermocouples. The heating of the furnace in the specified thermal range is a function of the type of hydrocarbon, the adduction flow rate of the hydrocarbon gas, and the development length of the ducts placed inside the furnace within which the hydrocarbon gas and the hydrogen formed by the thermal splitting process flows. For example, as the flow rate decreases and for duct developments of increasing length, it will be possible to operate at lower temperatures (because the gas per unit mass has more time to absorb the energy required for splitting) than those to be applied at higher flow rates and lower duct developments (because the gas per unit mass, in the latter case, has less time to absorb the energy required for splitting).
[0085] According to a preferred aspect of the present disclosure, the reactor 10 according to any of the embodiments described above is a part of a pyrolysis plant 100 that includes a removal apparatus 50, for removing carbon C, i.e. , for removing carbon C formed in the closed chamber 31. The removal apparatus 50 is a part of the pyrolysis plant 100, is preferably arranged below the bottom wall 14 and is placed in communication with the closed chamber 31 , then with the open mouth of the inner duct 26 by a passage in the bottom wall 14. Due to the geometry of the parts, the outer duct 25 engages in the bottom wall in such a way as to isolate the passage from the closed chamber 31 and the carbon removal apparatus 50. The removal apparatus 50 is placed in communication with the closed chamber 31 and the open mouth of the inner duct 26 through a first communication opening 51 , or first door. A closing leaf 52, for example having two wings hinged in the middle, is placed on the first communication opening 51 to close said first communication opening 51 ; said closing leaf 52 has a valve function and can be understood, by its function, as a carbon C removal valve. More specifically, the removal apparatus 50 includes a box structure 53 defining a collection chamber 54 of carbon C located, as mentioned, below the bottom wall 14. By periodically moving or operating the closing leaf 51 (Figures 3 and 4), it is possible to open the first communication opening 51 and drop carbon C onto a bottom of the collection chamber 54 (Figure 4).
[0086] In turn, the collection chamber 54 can be provided with a second communication opening 56, or second communication door, and equipped with another closing leaf 57, which when moved or operated (Figure 5) allows total removal of carbon C from the bottom of the plant. In other words, the pyrolysis plant 100 includes the removal apparatus 50 that enables a systematic and periodic collection of carbon C by action on the closing leaf. Such a systematic opening for both receiving carbon C and escaping carbon C from the collection chamber 54 allows for removal of carbon C from the respective openings as needed.
[0087] This prevents the progressive deposition of solid carbon C from clogging the ducts. Thus, a system of periodic removal of crystallized carbon C deposited on the walls is achieved, which may not involve shutting down the furnace for extraction and does not allow oxidation of carbon C at high temperature as it is extracted from the catalytic pyrolysis ducts. In fact, due to the closed chamber 31 , carbon C is not in contact with the heating chamber 12a.
[0088] Inert gas is intended to be fed into the collection chamber 54 with a respective duct (not shown) to remove oxygen.
[0089] It follows that the extraction system is made to detach the carbon C that is deposited on the duct walls without turning off the furnace (to let it cool) and without the carbon C burning in contact with oxygen.
[0090] Preferably, the reactor includes means of vibration of a known type, indicated schematically as 70, capable of striking the outer duct 25 and / or the inner duct 26, or otherwise causing a vibration. The location of the means of vibration is preferably in a top area of the heating chamber 12a. The percussion or vibration may be continuous or periodic. The means of vibration or percussion 70 may be means known, for example, mechanical in nature to a branch engineer, and capable of causing percussion or vibration on the ducts.
[0091] Percussion and vibration cause carbon C to detach, and this releases the catalase surface and causes carbon C to accumulate on the extraction valve.
[0092] For example, at regular time intervals or as a result of changes in flow rate measured by a detector, indicating the gradual decrease in duct clearance, the flow of hydrocarbon is stopped, inert gas is introduced into the collection chamber 54, also called the removal chamber 54, or a low pressure is imposed in the removal chamber, and the first closing clapper 51 is opened (Figure 4).
[0093] Once the first closing leaf 51 is closed again and when the temperature in the removal chamber 54 (measured by thermocouple) is below a temperature set by the user, the second closing leaf 57 is opened to discharge carbon C to the outside (Figure 5).
Claims
CLAIMS1. Pyrolysis reactor (10) for pyrolysis of hydrocarbons and formation of hydrogen and carbon (C), in which the pyrolysis reactor (10) comprises:- A furnace (12) having a heating chamber (12a), said heating chamber (12a) having a bottom zone (14a), and- at least one tubular reaction structure intended to allow a pyrolysis reaction, arranged at least partially within the heating chamber (12a) and connected with an external zone located outside the heating chamber (12a) to allow a hydrocarbon input and a hydrogen output, the pyrolysis reactor being characterized by the fact that the reaction tubular structure includes anouter duct (25) and an inner duct (26) that are placed inside each other to define an intermediate space (30) between the inner duct (26) and the outer duct (25) and extend from a top zone (15a) of the heating chamber (12a), or zone higher than the bottom zone (14a), toward the bottom zone (14a), wherein one between the outer conduit (25) and the inner conduit (26) is configured for hydrocarbon input and the other is configured for hydrogen output, whereinan inner conduit port (26) facing the bottom zone (14a) is surrounded by said outer conduit (25) and places in fluid communication the inner conduit (26) with said intermediate space (30) so as to define a communication zone (31) and create a flow of fluid passing through the inner conduit (26) and the intermediate space (30), or vice versa, through said inner conduit port (26), said outer duct (25) and inner duct (26) being made of gas impermeable material and being configured so that said fluid flow is unidirectional.
2. Pyrolysis reactor (10) according to claim 1 , wherein said communication zone (31) is configured to receive carbon (C) produced by pyrolysis at least by gravity.
3. Pyrolysis reactor (10) according to claim 2, wherein the outer conduit (25) is closed with respect to the heating chamber (12a) to isolate said communication zone (31) and form a closed chamber, said closed chamber including said communication zone (31) and being closed with respect to the heating chamber, and wherein the mouth of the inner conduit (26) is in fluid communication with said closed chamber (31).
4. Pyrolysis reactor (10) according to any one of the preceding claims, wherein said internal conduit (26) is intended to allow hydrocarbon input and said intermediate space (30) is intended to allow a hydrogen output.
5. Pyrolysis reactor (10) according to any of the preceding claims, wherein the inner duct(26) and outer duct (25) are tubes of circular or square cross-section.
6. Pyrolysis reactor (10) according to any of the preceding claims, wherein the inner duct(26) and the outer duct (25) are arranged vertically in the heating chamber (12a).
7. Pyrolysis reactor (10) according to any one of the preceding claims, wherein the inner conduit (26) and the outer conduit (25) are attached on one side to a top wall (15) of the furnace (12).
8. Pyrolysis reactor (10) according to any one of the preceding claims, wherein the outer duct (25) engages a bottom wall (14) of the furnace (12) to isolate said communication zone (31) from said heating chamber (12a).
9. Pyrolysis reactor (10) according to any of the preceding claims, including metal catalysts at least on the inner conduit (26).
10. Pyrolysis reactor (10) according to any of the preceding claims including heaters arranged in the heating chamber (12a).
11. Pyrolysis reactor (10) according to any one of the preceding claims including means for vibrating (70) said first conduit (25) and / or said second conduit (26).
12. Pyrolysis plant (100) including a pyrolysis reactor (10) according to any one of the preceding claims, said pyrolysis plant (100) comprising a removal apparatus (50) for removing carbon (C) formed in the communication chamber (31), said removal apparatus (50) being configured to be placed in communication with the communication zone (31).
13. Pyrolysis plant (100) according to claim 12, in which the removal apparatus (50) is arranged below the bottom wall (14).
14. Pyrolysis plant (100) according to claim 13, wherein the removal apparatus (50) is adapted to be put in fluid communication with the open mouth of the inner duct (26), by means of a passage or door (51) made in the back wall (14)15. A pyrolysis plant (100) according to any one of claims 12 to 14, wherein the removal apparatus (50) includes a closure leaf (52) having the function of a valve, said closure leaf (52) being selectively operable to allow a removal of carbon (C) through the door or opening (51).
16. A pyrolysis plant (100) according to any one of claims 12 to 15, wherein the removal apparatus (50) includes a box structure (53) defining a collection chamber (54) intended for collection of carbon (C) via said door or opening (51).
17. Pyrolysis plant (100) according to the preceding claim, including means to remove oxygen from said collection chamber (54).
18. A pyrolysis plant (100) according to any one of the preceding claims, wherein said door or opening is a first opening, and said removal apparatus (50) includes a second door or second opening (56) in a bottom wall of the collection chamber (54), wherein said second door or second opening (56) is provided with respective closing leaf (57) selectively operable for a removal of carbon (C) from the pyrolysis plant (100).
19. Pyrolysis process for pyrolysis of hydrocarbons and formation of hydrogen and carbon (C), wherein the process comprises the steps of:- Arranging at least one first duct in a pyrolysis heating chamber so that said first duct is affected by a top-down oriented flow;- Arranging at least a second duct in the heating chamber so that said second duct is affected by a flow oriented from the bottom to the top;- connecting said first conduit with said second conduit so that a communication zone of said first conduit with said second conduit is in a bottom zone or a lower zone of the heating chamber than a remaining part of the first conduit and the second conduit;- Entering hydrocarbons through the first conduit;- Determining a thermal splitting of hydrocarbons along at least the first conduit;- leaking hydrogen by passing through the second conduit;- dropping by gravity toward said communication zone at least some carbon (C) produced by pyrolysis.
20. Pyrolysis process according to the previous claim, in which temperatures from 550°C to 1200°C are reached in the heating chamber.
21. Pyrolysis process according to claim 19 or 20, which is carried out through a pyrolysis reactor (10) according to any of claims 1 to 11 .
22. Pyrolysis process according to claim 19, 20 or 21 , which is carried out through a pyrolysis plant (100) according to any of claims 12 to 18.
23. Pyrolysis process according to claim 22, in combination with claim 16, wherein the amount of carbon (C) in the first conduit and / or second conduit is controlled and the first communication opening is opened, oxygen is removed in the collection chamber (54) and carbon (C) is dropped into the collection chamber (54).
24. Pyrolysis process according to claim 23 and in combination with claim 18, wherein after collecting carbon (C) on one bottom of the collection chamber (54) the second opening (56) is opened for a total removal of carbon (C) from the bottom of the plant.