Reactor and method for performing a chemical reaction

Abstract

The invention relates to a reactor (100, 200) for carrying out chemical reactions, comprising a reaction vessel (10) and one or more reaction tubes (20), a number of tube sections (21, 22) of which in each case extend between a first zone (11) and a second zone (12) in said reaction vessel (10), and in each case the tube sections (21, 22) in the first zone (11) are electrically connected or can be connected to one or more current connections (U, V, W) of a current source (50) for electrical heating of the tube sections (21, 22). The first region (11) of the reactor (100, 200) is provided with a current supply arrangement (40), to which in each case one of the tube sections (21, 22) or in each case one group of the tube sections (21, 22) is electrically connected, each current supply arrangement comprising in each case one or more contact passages (42) adjacent to at least one of the tube sections (21, 22) in the first region (11), the walls of which are in each case connected to a current supply element (41) having a rod-shaped portion (43) extending in a wall passage (15) through the wall (14) of the reactor vessel (10). A corresponding method is also the subject of the present invention.

Description

Technical Field

[0001] The present invention relates to a reactor and a method for carrying out a chemical reaction according to the preamble of the independent claim.

Background Art

[0002] In many processes in the chemical industry, reactors are used in which one or more reactants pass through heated reaction tubes where they react, either catalytically or non-catalytically. Heating in particular helps to overcome the activation energy required for the ongoing chemical reaction. This reaction can proceed endothermically overall or exothermically after overcoming the activation energy. The present invention relates in particular to strong endothermic reactions.

[0003] Examples of such processes are steam cracking, various reforming processes, in particular steam reforming, dry reforming (carbon dioxide reforming), mixed reforming processes, dehydrogenation processes of alkanes, etc. During steam cracking, the reaction tubes are guided through the reactor in the form of a coil that can have at least one U-shaped bend within the reactor, while tubes passing through a reactor without a U-shaped bend are typically used in steam reforming.

[0004] The present invention is suitable for all such processes and the design of reaction tubes. The articles "Ethylene", "Gas Production", and "Propene" in Ullmann's Encyclopedia of Industrial Chemistry, for example, the publication dated April 15, 2009, DOI: 10.1002 / 14356007.a10_045.pub2, the publication dated December 15, 2006, DOI: 10.1002 / 14356007.a12_169.pub2, and the publication dated June 15, 2000, DOI: 10.1002 / 14356007.a22_211 are hereby incorporated by reference purely for illustrative purposes.

[0005] The reaction tubes of the corresponding reactors have conventionally been heated using burners. In this case, the reaction tubes are sent through a combustion chamber in which the burners are also arranged.

[0006] However, as described, for example, in DE 10 2015 004 121 A1 (similarly EP 3 075 704 A1), the demand for synthesis gas and hydrogen produced, for example, regardless of the presence or absence of reduced local carbon dioxide emissions, is currently increasing. However, this demand typically cannot be met in processes where combustion reactors are used by the combustion of fossil energy carriers. For example, other processes are excluded for reasons such as high costs. The same applies to the production of olefins and / or other hydrocarbons by steam cracking or dehydrogenation of alkanes. Even in such cases, processes with at least a low amount of carbon dioxide emissions generated on-site are desired.

[0007] Against this background, the aforementioned DE 10 2015 004 121 A1 proposes, in addition to combustion, the electrical heating of a reactor for steam reforming. In this case, one or more voltage sources that supply a three-phase alternating voltage to three external conductors are used. Each external conductor is connected to a reaction tube. A star circuit in which a star point is realized is formed by a pipeline opening and a collector to which the reaction tubes are conductively connected. In this way, the collector ideally remains at zero potential. With respect to the vertical line, the collector is arranged below and outside the combustion chamber and preferably extends transversely to the reaction tubes, i.e., horizontally. WO 2015 / 197181 A1 also discloses a reactor in which the reaction tubes are arranged in a star point circuit.

[0008] In principle, it is also conceivable to carry out the electrical heating of the reactor by direct current or single-phase alternating current. In this case, a star circuit with a zero-potential star point cannot be realized. However, in principle, the current supply can also be realized in a similar manner. The present invention is suitable for both variants of electrical heating.

[0009] DE 23 62 628 A1 discloses a tubular furnace for the heat treatment of a liquid or gaseous medium in a metal tube that can be heated by resistance heating, where the tube heated by resistance heating is conductively connected to a current supply line via an electrical connection at the end of the heated portion.

[0010] US 2014 / 0238523 A1 relates to a device for heating a pipeline system for molten salt, the device comprising at least two pipelines, in each case along which an electrical resistance heating element extends, the electrical resistance heating element having at least one end set to a potential close to ground potential, and the electrical resistance heating element being remotely connected to a connection of a DC power source or, in each case, to a phase of an n-phase AC power source.

[0011] In particular, it has proven difficult in such electrically heated reactors to supply current due to the flow of current and high temperatures. Therefore, the object of the present invention is to improve the corresponding electrically heated reactor for carrying out chemical reactions.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Non-Patent Documents

[0013]

Non-Patent Document 1

[0014] In view of this background, the present invention proposes a reactor and a method for carrying out a chemical reaction according to the preamble of the independent claims. Embodiments are the subject of the dependent claims and the following description.

[0015] In the concept of an at least partially electrified furnace (the term "furnace" is generally understood to refer to the corresponding reactor or at least its insulated reaction space), which is the basis of the present invention, at least one reaction tube or its corresponding tube section (hereinafter also abbreviated as "tube") itself is used as an electrical resistor for generating heat. This strategy has the advantages of high efficiency and high achievable heat flux density compared to indirect heating by external electrical heating elements. The scope of the present invention also includes the possibility of providing a part of the total heat output used in the furnace by combustion of chemical energy carriers.

[0016] Therefore, even if electrical heating is mentioned herein, the presence of additional non-electrical heating is not excluded. In particular, it is also conceivable that the contributions of electrical heating and non-electrical heating change over time as a function of, for example, the supply and price of electricity, or the supply and price of non-electrical energy carriers such as natural gas.

[0017] When heating with polyphase alternating current, the current is supplied to the directly heated reaction tube via M separately connected phases. It is advantageous for the conductive reaction tube connected to the M phases to also be electrically connected to the star point. The number of phases M is in particular 3 and corresponds to the number of phases of a conventional three-phase current power supply or three-phase current network. However, in principle, the invention is not limited to the use of 3 phases and can also be used with a greater number of phases, for example 4, 5, 6, 7, or 8 phases. Thereby, the phase offset becomes in particular 360° / M, i.e. 120° for three-phase current.

[0018] In an electric heating system with polyphase alternating current, equipotentialization between phases is achieved by a star circuit at the star point that obviates the need for electrical insulation of the connected pipelines. This represents a particular advantage of such a furnace concept since the breakage of a metal reaction tube for insulating certain parts is undesirable, especially when high temperatures are used and the required material and construction costs are high.

[0019] However, the measures proposed according to the invention described below are equally suitable for the use of direct current and the invention can be used in reactors that are heated by both alternating current and direct current or in corresponding hybrid forms. In the case of a direct current configuration, only the type of current source and the region of the reaction tube facing the current supply or the corresponding part on which the current acts differ from the alternating current configuration. In the latter, the electrical connection of the different tube parts is only carried out optionally. Since there is no star point of zero potential in the direct current configuration, it is necessary to provide a suitable current discharge element that safely returns the current flow back to the outside. The same also applies in principle to single-phase alternating current, which can also be used.

[0020] In the language of the claims, the present invention relates to a reactor for carrying out a chemical reaction, which reactor comprises a reaction vessel (i.e., a thermally insulated or at least partially thermally insulated region) and one or more reaction tubes, in each case a large number of tube portions of the one or more reaction tubes extending between a first region and a second region within the reaction vessel through an intermediate region between the first region and the second region, and for electrical heating of the tube portions, the tube portions in the first region are in each case electrically connected or connectable to one or more electrical connections, in the case of a DC configuration, electrically connected to one or more DC connections, and in the case of a single-phase or polyphase AC configuration, connected to the phase connection of an AC power supply ("external conductor").

[0021] In particular, the first region is at the first end of the straight tube portion and the second region is at a second end opposite the first end. In particular, the first region is in the upper region of the reactor and the second region is in the lower region of the reactor, or vice versa. In other words, the first region and the second region are located in particular at opposite ends of the reaction vessel or its interior, and the interior of the reaction vessel between the first region and the second region corresponds in particular to the intermediate region. The first region can represent or include, for example, 5%, 10%, or 20% of the inner end of one end of the reaction vessel, while the second region can represent or include 5%, 10%, or 20% of the other opposite end of the interior of the reaction vessel. In particular, during operation of the reactor, the first region is arranged at the bottom and the second region is arranged at the top.

[0022] As described above, in the polyphase AC configuration, the AC voltage is in each case supplied via the phase connection, and the AC voltage of the phase connection is phase-shifted in the manner described above. Within the scope of the present invention, for example, a supply network or a suitable generator and / or transformer can function as a polyphase AC power supply. In this configuration, the tube portions in particular form a star circuit and are conductively coupled to each other at their respective ends located on the opposite side of the current supply, i.e., in the second region.

[0023] However, in the case of a DC configuration, the same or different electrostatic potentials are supplied via a DC connection, and the current extraction element or the current discharge element is provided at the end opposite to the current supply in any case. The terms "supply" and "extract" may refer to the physical or technical flow direction. A single-phase AC power supply is used in an equivalent manner.

[0024] In the intermediate region, the tube portion passes through the reaction vessel particularly freely, i.e., without mechanical support, without electrical contact, and / or without fluid or purely mechanical interconnection. The tube portion extends particularly substantially or completely straight in the intermediate region, where "substantially straight" should be understood to mean that there is an angular deviation of less than 10° or 5°.

[0025] In particular, the decomposition reaction in steam reforming is a strong endothermic reaction. Therefore, to provide the energy required for the reaction by direct heating (ohmic resistance), the high current intensity provided by one or more transformers arranged outside the reactor is required in the concept of the reactor described above.

[0026] The current must be conducted from outside the adiabatic reactor to the inside and to the process-bearing region with as low a loss (low electrical resistance) as possible. In the latter case, an endothermic reaction (high heat transfer) with the process medium flowing very rapidly inside the tube results in very effective cooling of the reaction tube or a very high heat flux density inside the tube. Therefore, the desired direct heat transfer from the at least partially electrically heated tube material to the process gas is achieved inside the process-bearing tube.

[0027] Specific problems are associated with the above-described low-loss supply of high current to the process-bearing tubes. As will be explained below, when current is supplied to the tubes in the reactor through conductors that cannot be cooled by direct convective heat transfer to a cooler process gas, such supply must necessarily be made. Here, in regions of low cooling efficiency, there must be no unacceptable temperature rise. Furthermore, such supply must also overcome a rapid temperature rise of up to 900 K (the maximum temperature difference between the environment and the reactor) within a short path length (partially less than 1 meter).

[0028] To reduce heat loss and achieve high system efficiency, it is essential to place the electrically directly heated reaction tube in a heat-insulated box (herein called the reaction vessel). During the penetration of the heat-insulated wall of the reaction vessel, the current conductor must overcome the quasi-insulated zone without generating an unacceptably high local temperature in such a region.

[0029] According to the present invention, in order to achieve such an object in the first region of the reactor, i.e., the region of current supply, a current supply configuration is provided, to each of which a tube portion or a group of tube portions is electrically connected. The tube portions are provided in such a number that in any case one of the plurality of tube portions, or in any case one group of the plurality of tube portions, can be connected to one of the current supply configurations and vice versa. The number of current supply configurations is based on the number of phase connections of a polyphase AC power supply in the case of an AC configuration, or such number corresponds to the number of DC connections. When an AC configuration is used, it can be made the same as the number of phase connections or an integer multiple thereof. In the latter case, for example, two of the current supply configurations can be connected to one of the phase connections of the AC power supply in any case.

[0030] Each current supply configuration includes one or more contact passages that are adjacent to at least one of the tube portions within the first region and extend through the current supply configuration. One or more contact passages within the current supply configuration can extend straight through the current supply configuration or in the form of a U-shaped bend, as will be described in more detail below. The contact passages are formed in particular as bends reinforced by walls. The reaction tube without a U-shaped bend is in particular a sleeve reinforced by walls.

[0031] Within the scope of the present invention, one or more contact passages within the current supply configuration are attached to the tube portion in a high-temperature resistant manner and are one or more components that are firmly bonded, or in any case, are formed in the form of a part or a continuous part of the reaction tube. As will be described below, it is generally known that in all embodiments, a design with as few components as possible is advantageous.

[0032] In the former case, the tube portion extending between the first region and the second region within the reactor can be welded to a ready-made component through which one or more contact passages extend, or the corresponding additional component is molded onto the tube portion extending between the first region and the second region within the reactor. In the latter case, on the one hand, a continuous tube can be provided that extends between the first region and the second region within the reactor and, on the other hand, forms the contact passages of each current supply configuration, and the additional components of the current supply configuration can be provided by molding, remolding, or welding.

[0033] When referring above and below to the fact that the current supply configuration includes one or more contact passages that are "in any case adjacent to at least one of the tube portions within the first region", this is understood to mean that the contact passages of the current supply configuration, together with each tube portion between the first region and the second region, form a continuous channel for the process fluid to pass through the tube portion.

[0034] In particular, the interior of the tube of each tube portion between the first region and the second region continues into the corresponding contact passage without any significant taper or enlargement, where "significant" taper or enlargement is intended to denote a taper or enlargement of more than 10% of the cross-sectional area. The term "contact passage" is used in certain embodiments of the present invention to denote that the "contact passage" may be a continuous extension of the tube portion within the first region or a region where there is an electrically conductive connection to the current connection via a metallic component.

[0035] The term "robustly bonded in a high-temperature resistant manner" is intended to specify a type of connection in which two or more metal parts are robustly bonded to each other and the connection is permanent at temperatures from 500 °C to 1,500 °C, in particular from 600 °C to 1,200 °C, or from 800 °C to 1,000 °C, i.e., it does not separate at such temperatures during normal operation. A connection that is robustly adhesively bonded in a high-temperature resistant manner can in particular be formed as an intermetallic connection designed such that no non-metallic material remains between the connected parts. Such a connection is in particular produced by welding, molding, or remolding. It can also be a connection where no structural differences are observed at the transition of the connected parts, in particular a connection where no additional metal is used for the connection.

[0036] According to the present invention, the walls of the contact passages of each current supply configuration are in each case connected to a current supply element having at least one rod-shaped portion that extends in a wall passage through the wall of the reaction vessel. The "wall" of the reaction vessel may be an intermediate wall to another space where the rod-shaped portion is contacted, and is delimited by a further wall or a plurality of walls. The rod-shaped portion is, in particular, integral by a conductive material such as metal (i.e., not in the form of, for example, strands or the like), in contrast to, for example, strands. The rod-shaped portion can be formed solid or at least partially tubular, i.e., as a hollow rod. The rod-shaped portion has a longitudinal extension perpendicular to the wall of the reaction vessel, and the longitudinal extension is at least twice, in particular at least three times, four times, or five times, for example up to ten times, the size of the maximum transverse extension parallel to the wall of the reaction vessel. The rod-shaped portion can be formed, for example, such that its cross-section is circular, elliptical, triangular, or polygonal, or can have any other shape.

[0037] The current supply elements of the current supply configuration can be directly attached to the walls of the contact passages with their rod-shaped portions, or can be transferred into the contact passages by single molding. However, one or more intermediate elements can also be provided, which then in each case form part of the current supply element.

[0038] According to the present invention, the introduction of current into the reaction tube or its tube portion to be heated is preferably carried out in a direction perpendicular to the local process gas flow, via a rod-shaped portion attached to the process carrier tube, i.e., in particular at the apex of a U-shaped bend, or in the case of a non-curved tube, perpendicular to the path of the tube. Here, in particular, a free conductor cross-sectional area that decreases overall from the outside towards the reaction zone can be present in the rod-shaped portion having a homogeneous material composition. This relates to both the rod-shaped portion and the transition region to the reaction tube or the contact passage, and the contact passage preferably has an enlarged wall thickness compared to the reaction tube away from the feed.

[0039] Particularly advantageous embodiments of the invention are such that the root mean square (rms) value of the potential Vrms,i is in each case constant, and for any two cross-sectional areas S1, S2 representing an insulating surface through which a current supply element is arranged at different distances from an alternating voltage source, in particular a transformer, the time-averaged root mean square potential Vrms,1 of the cross-sectional area S1 located close to the transformer is always higher than the time-averaged root mean square potential Vrms,2 of the cross-sectional area S2 located further away from the transformer, i.e., Vrms,1 > Vrms,2. The terms "closer" and "farther" here refer to shorter or longer current paths from the current source to the respective cross-sectional areas. The use of the rms value of the potential refers to the operation of the reactor with alternating current. In the case of direct current operation, the described relationship applies to the arithmetic mean value of the potential.

[0040] The total current supply (i.e., the entire supply element with the contact path) is at different distances from the current source, and for the two arbitrary cross-sectional areas S1, S2 described with Vrms,1 > Vrms,2, the quotient A2 / A1 of the surface area A2 of the cross-sectional area S2 located farther away from the current source and the surface capacitance A1 of the cross-sectional area S1 located closer to the current source is designed even more advantageously such that it is at most 0.5, in particular at most 0.9, at most 1, at most 1.1, or at most 2. In a particularly preferred embodiment, the quotient A2 / A1 of the surface areas of such an arbitrary pair of regions is at most 1.

[0041] For example, due to manufacturing reasons, deviations from this preferred embodiment may occur, and as a result, even a slight increase in cross-sectional area may be locally acceptable. However, if the two cross-sectional areas S1 * and S2 * have the overall extreme values of their respective surface areas A1 * = Amax and A2 * = Amin, it is advantageous for the relationship to always be Vrms,1 * > Vrms,2 * i.e., the region with the largest cross-sectional area is closer to the current source than the region with the smallest cross-sectional area.

[0042] As described, an optimal continuous increase in the material temperature can be ensured, where the maximum value is reached, particularly preferably, only in the reaction zone. According to a particularly advantageous embodiment of the invention, as a specification regarding the temperature distribution, for any two arbitrary cross-sectional areas S1 and S2 described, where Vrms,1 > Vrms,2 at different distances from the current power supply, the temperature difference T1 - T2 between the temperature T1 of the cross-sectional area S1 located closer to the current power supply and the temperature T2 of the cross-sectional area S2 located farther from the current power supply is at most -100 K, particularly at most -10 K, at most -1 K, at most 0 K, at most 1 K, at most 10 K, or at most 100 K, and can be specified in the same way as the area distribution. In a particularly preferred embodiment, the temperature difference T1 - T2 for all pairs of such cross-sectional areas is less than 0 K.

[0043] This specification includes, inter alia, the condition that a maximum local temperature increase of -100 K, -10 K, -1 K, 0 K, 1 K, 10 K, or 100 K occurs in the entire area of the current supply in relation to the maximum material temperature occurring in adjacent pipe sections.

[0044] In the current supply element, for cross-sectional areas S1 * = Amax and A2 * = Amin having the overall extreme values, * and S2 * the temperature difference T1 * and T2 * of the temperatures T1 * - T2 * is more preferably at most -500 K, at most -200 K, at most -100 K, at most 0 K, or at most 100 K, i.e., the region having the highest cross-sectional area according to this embodiment of the invention needs to be arranged close to the transformer, and it is desirable that it is either cooler or at most slightly warmer than the region with the smallest cross-sectional area.

[0045] The current supply element is preferably initially formed as a solid material rod from the direction of the current power supply towards the pipe section and leads to a contact passage arranged close to the pipe section. The contact passage can be formed up to a relatively thin-walled reaction tube or the heated pipe section, particularly as a thick-walled bend or sheath.

[0046] In one embodiment of the present invention, the free conductor cross-sectional area advantageously mainly decreases continuously or monotonically. For the same or similar materials provided in this embodiment, since the electrical resistance depends only on the available conductor area, a specific amount of the released energy also increases steadily in this way. Thereby, only the amount of heat absorbed by the process gas is effectively used in the reaction tube, so that the supplied energy is utilized to the maximum extent.

[0047] According to a particularly advantageous embodiment of the present invention, the exact path of the conductor cross-section is further adapted to the local temperature and heat transfer conditions. For example, in the region of a quasi-adiabatic wall passage passing through the wall of the reaction vessel (where significant heat dissipation through the insulating reactor wall is impossible), a large cross-section that minimizes the local heat dissipation in such a region is preferably used so that the local temperature rise can be limited upward. In other words, the rod-shaped portion of the current supply element preferably has a larger cross-sectional area in the region of the wall passage than at least one of the remaining regions. As will be described later, since the rod-shaped portion is displaceably guided within the wall passage, the region of the rod-shaped portion "within the region of the wall passage" should be understood to mean at least one such region that is arranged within the wall passage during the maximum thermal expansion of the tube portion.

[0048] As will also be explained below, in order to avoid contact resistance, at least in the rod-shaped portion, the current supply element and the contact portion are particularly preferably integral components, for example, made in the form of upright molded parts. Alternatively, in the case of a multi-part structure, which is likewise possible, preferably, appropriate joining methods (for example, friction welding) are ensured such that the specifications described with respect to the conductor cross-section and the maximum local temperature rise are maintained even in the region of the joining connection.

[0049] Particularly advantageously, each current supply element has, at any point, a free conductor cross-sectional area that is not less than 10 square centimeters between each wall passage of the current supply element and the point on the wall of one or more contact passages that is closest to the wall passage and is electrically contacted by the respective current supply element. Advantageously, at any point, it is not less than 30 square centimeters, and particularly at any point, it is not less than 50 square centimeters. By using a correspondingly high conductor cross-sectional area, it is possible to ensure particularly good current transmission without resistance losses.

[0050] Here, the free conductor cross-sectional area is intended to indicate the ratio of the cross-sectional area of a conductor formed to be conductive. For example, in the case of a tubular conductor or a conductor provided with a groove or cavity, the area inside the tube or the area of the groove or cavity is not regarded as the free conductor cross-sectional area. In contrast, in the case of a solid conductor made of a conductive material, this cross-sectional area corresponds to the conductor cross-sectional area and the free conductor cross-sectional area.

[0051] According to the present invention, the rod-shaped portions of the current supply elements are each guided in a longitudinally movable manner within those wall passages that pass through the wall of the reaction vessel. The freedom of movement thus ensured is particularly advantageous for the mechanical behavior of the reaction tube, which is mainly governed by the thermal expansion of the tube by several decimeters during the operation of the reactor. The freedom of movement reduces the bending load on the reaction tube that occurs in the case of rigid fixation. On the other hand, as will be described later, the reaction tube can be fixed to a rigid stub bridge on the roof of the reactor in a second region, and in this way, even if there is a corresponding longitudinal mobility of the rod-shaped portions of the current supply elements, a stable suspension is provided. Due to their advantageous dimensions with a sufficiently high conductor cross-sectional area, the rod-shaped portions of the current supply elements ensure reliable lateral guidance of the reaction tube.

[0052] The reaction carried out in the reactor according to the present invention requires a high temperature. Therefore, the electrical connection in the first region must be carried out in a high temperature range of, for example, about 900 °C for steam reforming. This is made possible by the measures proposed by the present invention by selecting appropriate materials and their appropriate dimensions. At the same time, this connection is intended to have high electrical conductivity, high mechanical stability and reliability at high temperatures. A failure of the electrical connection results in an asymmetric potential at the star point, and as a result, undesirable currents flow through the system components, leading to an instantaneous shutdown of the safety-related parts of the system. The present invention provides an advantage over the prior art by avoiding such situations.

[0053] The contact of the tube portion within the reaction vessel provided by the present invention has the advantage that the cross-sectional area of the electrothermal input is clearly defined compared to the contact outside the reaction vessel, where the reaction tube must be drawn out of the reaction vessel, which is theoretically equally possible. This is because in this case, there is no need to conduct the electrically heated tube portion from the warm inside to the cold outside. By the contact according to the present invention, with the tube portion being completely arranged within the reaction vessel, it is possible to achieve highly uniform external thermal boundary conditions with respect to the space of the electrically heated tube portion. This provides process engineering advantages, for example, it is possible to avoid excessive coke formation expected in a heated and externally insulated passage.

[0054] Outside the reaction vessel, the rod-shaped portion of the current supply element can be electrically connected to the transformer system by connection elements such as busbars or connection bands. The connection bands and busbars can be made of different materials. Such connection elements are formed to be particularly flexible. This is because the outside of the reaction vessel is at a lower temperature. In particular, on the primary side of the transformer system, high voltage and low current exist, so a switching device can be attached.

[0055] Within the scope of the present invention, the current supply element, the contact path, and the tube portion may be formed from the same material or from materials having an electrical conductivity that differs from each other by 50% or less, 30% or less, 10% or less (from the perspective of material constants), as is customary in the industry, or preferably, from the same material. For example, the components mentioned can also be formed from steel of the same steel grade. Using the same or closely related materials facilitates shaping or welding.

[0056] In a preferred embodiment, the current supply element, the contact path, and the tube portion have or are formed from a heat-resistant chromium-nickel steel alloy having high oxidation resistance or scale resistance and carburization resistance.

[0057] For example, the heat-resistant chromium-nickel steel alloy can be an iron-based material containing 0.1 to 0.5% by weight of carbon, 20 to 50% by weight of chromium, 20 to 80% by weight of nickel, 0 to 2% by weight of niobium, 0 to 3% by weight of silicon, 0 to 5% of tungsten, and 0 to 1% by weight of other components, and these components complement each other to form a non-ferrous fraction.

[0058] For example, materials with standard designations GX40CrNiSi25-20, GX40NiCrSiNb35-25, GX45NiCrSiNbTi35-25, GX35CrNiSiNb24-24, GX45NiCrSi35-25, GX43NiCrWSi35-25-4, GX10NiCrNb32-20, GX50CrNiSi30-30, G-NiCr28W, G-NiCrCoW, GX45NiCrSiNb45-35, GX13NiCrNb45-35, GX13NiCrNb37-25, or GX55NiCrWZr33-30-04 can be used in accordance with DIN EN 10027 part 1, "Materials". These have proven to be particularly suitable for use at high temperatures.

[0059] In all cases described above, the connecting element and the pipe section may be formed from the same material or from materials having an electrical conductivity that differs from each other by 50% or less, 30% or less, 10% or less (from the perspective of material constants, as is customary in the industry), or advantageously, the same. For example, the connecting element and the pipe section can also be formed from steel of the same steel grade. The use of the same or closely related materials can facilitate the integral design of the connecting element and the pipe section, for example, by molding or welding.

[0060] In the second region, all pipe sections within the reaction vessel can be conductively connected to each other by a rigid connecting element ("star bridge") when heated by polyphase alternating current, or such connections are made in groups by a plurality of rigid connecting elements.

[0061] In this case, i.e., in the case of heating by polyphase alternating current, the conductive connection is made such that at least a substantial equipotentialization of the phases connected to the first region occurs, as described. One or more connecting elements connect the connected pipe sections in a non-fluid collecting and non-fluid distributing manner, in particular, in contrast to the collectors arranged outside the reactor known from the prior art. The equipotentialization within the reaction vessel proposed in the described embodiments of the present invention has the advantage that the potential is almost completely eliminated or the return of current via the neutral conductor is significantly reduced. As a result, current dissipation via the header connection to other parts of the process system is minimized, and a high level of shock protection is achieved. In this context, the advantage of highly uniform external thermal boundary conditions with respect to space applies in contrast to the guiding of the reaction tubes outside the reaction vessel through the wall of the reaction vessel required for equipotentialization, and the process-related advantages have already been described above.

[0062] Overall, the realization of the corresponding star circuit in combination with the described current supply via a longitudinally guided current supply element creates a design that can withstand the stresses mainly resulting from the high coefficient of thermal expansion and enables efficient energization with simultaneous stable fixation.

[0063] This is also applicable to heating made possible by the present invention by direct current or single-phase alternating current. In this case, as described above, there is no star point in the reactor. Nevertheless, the reaction tube can expand substantially freely without generating stress by the current supply element provided by the present invention, so that a rigid configuration can be provided at the end opposite to the current supply. Therefore, a rigid configuration can be provided at the end of the reaction tube opposite to the current supply. If necessary, an element corresponding to the current supply element according to the present invention can also be provided here. However, in any case, the movable configuration can be omitted.

[0064] The present invention will first be described below with reference to the reaction tube and reactor used for steam reforming. However, as will be described later, the present invention can also be used for other types of reactors, as will be described later. Generally, as described above, the reactor proposed by the present invention can be used for performing any endothermic chemical reaction.

[0065] Reaction tubes typically used for steam reforming typically have at least one U-shaped bend. For example, these can be so-called two-pass coils. They have two tube portions in the reaction vessel and intersect with each other through (exactly) one U-shaped bend, so they basically have an (elongated) U shape. The portions entering and leaving the reaction vessel, especially the portions entering the heated tube portion seamlessly or without a transition related to the flow, are here called the "supply portion" and the "extraction portion" (also referring to the reaction tubes described below). There are always a plurality of such reaction tubes.

[0066] Therefore, in this embodiment, in any case, the reactor can be formed such that the tube portion includes two tube portions of a plurality of reaction tubes arranged at least partially side by side within the reaction vessel, and in any case, the two tube portions of the plurality of reaction tubes pass through each other in the first region via a U-shaped bent portion. In particular, as described above, in any case, one of the two tube portions in the second region is connected to the supply portion, and in any case, the remaining of the two tube portions in the second region is connected to the extraction portion.

[0067] In this case, one or more contact passages in the current supply configuration can include or represent a U-shaped bent portion. Since there are a plurality of reaction tubes having a U-shaped bent portion, if there are a corresponding number of U-shaped bent portions, a plurality of U-shaped bent portions can be provided for each of the respective current supply configurations and thus connected to the current connection in this way. In this way, mechanical fixation can be improved and the number of components can be reduced. However, instead, even when a plurality of U-shaped bent portions are energized via a current connection, in any case, it is also possible to provide one current supply configuration for each U-shaped bent portion, for example, to ensure the individual longitudinal mobility of current supply elements that may have different thermal expansions.

[0068] The described embodiments of the present invention can also be applied when reaction tubes having two supply portions and one extraction portion are used. In such reaction tubes, the two supply portions are each connected to one tube portion. The extraction portion is also connected to the tube portion. The tube portion connected to the supply portion intersects the tube portion connected to the extraction portion in a typical Y-shaped connection region. Both the tube portion connected to the supply portion and the tube portion connected to the extraction portion may or may not have one or more U-shaped bent portions, respectively.

[0069] For example, reaction tubes as shown in FIG. 7C can be used. In these reaction tubes, the tube portion connected to the supply portion has no U-shaped bent portion, but the tube portion connected to the extraction portion has a U-shaped bent portion.

[0070] However, reactor tubes such as those shown in Figure 7B can also be used, in which the tube sections connected to the feed sections each have one U-shaped bend and the tube sections connected to the extraction sections have two U-shaped bends.

[0071] It is even possible to use reactor tubes such as those shown in Figure 7A, in which the tube sections connected to the feed section each have three U-shaped bends, and the tube sections connected to the extraction section have two U-shaped bends.

[0072] However, in addition to the embodiments described above for two-pass coils, embodiments suitable for use with so-called four-pass coils can also be used. Four-pass coils have four essentially straight tube sections. However, configurations with a greater even number of straight tube sections are also possible.

[0073] More generally, a correspondingly designed reactor comprises one or more reaction tubes, each having an even number of four or more tube sections connected in series with one another via a number of U-shaped bends, the number of U-shaped bends being one less than the number of tube sections connected in series with one another via U-shaped bends, and the U-shaped bends being arranged alternately in the first and second zones, starting from the first U-shaped bend in the first zone.

[0074] Here, a "U-shaped bend" is understood to mean in particular a pipe section or pipe component with a part-circular or part-elliptical, in particular semicircular or semi-elliptical, pipe bend, the start and end of which have cut surfaces that are adjacent to each other in one plane.

[0075] Each U-shaped bend can be designed in the form of a contact path in the current supply arrangement according to the invention, or can represent part of such a contact path, provided that it is arranged in a first region in the reaction vessel and is energized accordingly.

[0076] As described above, the corresponding reactor can be designed, in particular, as a reactor for steam reforming, depending especially on the selection of the corresponding heat-resistant material and the geometric configuration of the reaction tubes.

[0077] Reaction tubes typically used for steam reforming typically do not have a U-shaped bend in the reaction vessel. In this case, each of the tube portions can comprise a tube portion consisting of a plurality of reaction tubes, and the tube portions in the reaction vessel are arranged at least partially side by side in a non-fluidly communicating manner, and in any case are connected to a supply portion for the fluid in the first region and an extraction portion for the fluid in the second region. The fluid supply portion and the extraction portion do not, in particular, extend in the same direction as the tube portion or cause a fluid flow that deflects by more than 15° with respect to the fluid flow in the connected tube portion. The supply portion and the extraction portion are, in particular, also formed integrally with the tube portion, i.e., in particular, in the form of the same tube. In particular, the reaction tubes may also be provided with a suitable catalyst for steam reforming.

[0078] In this embodiment, the contact path of the current supply configuration according to the invention represents a straight tube portion or a channel. Here, the current supply element can be attached to the reaction tube in the second region, in particular in a sleeve manner.

[0079] In all cases, the number of intermetallic connections (e.g., welded or soldered connections) can be reduced or even completely eliminated by forming the current supply element, the contact path, and optionally the tube portion from as few individual parts as possible. This can enhance mechanical stability and reliability. In a particularly advantageous embodiment, the current supply element and the contact path can each be implemented as a single molded article, or as described above, a part of the process-supporting tube can be remolded, and / or a part of the process-supporting tube can be formed as an integral part of the corresponding molded article.

[0080] Metal-to-metal connections or metal migrations that are reduced within the scope of the present invention can lead to local changes in electrical resistance and thus hot spots. Hot spots can lead to a shortening of the service life due to an increase in local temperature and peaks in mechanical stress due to a sharp local temperature gradient. This is avoided within the scope of the present invention.

[0081] The integrated design of as many components as possible results in mechanical stability, reliability, and a reduction of the individual components. As mentioned above, high mechanical stability is desirable because failures can lead to critical safety situations. According to the embodiments described from the perspective of the present invention, the principle of a reaction tube resistively heated with polyphase alternating current in a star circuit is technically feasible in a high temperature range, namely in particular above 500 °C, above 600 °C, above 700 °C, or above 800 °C.

[0082] The present invention also relates to a method for carrying out a chemical reaction using a reactor having a reaction vessel and one or more reaction tubes, wherein a number of tube portions of the one or more reaction tubes each extend between a first region and a second region in the reaction vessel, and each of the first regions for heating the tube portions is electrically connected to one or more current connections of a current source.

[0083] According to the present invention, a reactor having a current supply configuration in which, in any case, one of the tube portions or, in any case, a group of one of the tube portions is electrically connected is used, and each of the current supply configurations in any case comprises one or more contact passages that contact at least one of the tube portions within the first region, and the walls of the contact passages are in any case connected to a current supply element having at least one bar-shaped portion, and the bar-shaped portion in any case extends through the wall of the reaction vessel and extends in a wall passage.

[0084] For further features and advantages of the corresponding method in which a reactor according to one of the embodiments of the present invention described above is advantageously used, reference is made to the above description.

[0085] The present invention will be further described below with reference to the accompanying drawings showing embodiments of the present invention, with reference to and comparison with the prior art.

Brief Description of the Drawings

[0086]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 5C

Figure 6A

Figure 6B

Figure 7A

Figure 7B

Figure 7C

Figure 8

Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[0087] In the following figures, elements that are functionally or structurally corresponding to each other are denoted by the same reference numerals and will not be repeatedly described for clarity. When the components of the device are described below, the corresponding descriptions are related to the method executed thereby in any case, and vice versa. The description of the figures repeatedly refers to alternating current heating. However, as mentioned, the present invention is also equally suitable for the use of direct current for heating. Here, the above description is referred to.

[0088] FIG. 1 schematically shows a reactor for carrying out a chemical reaction according to an embodiment not according to the present invention.

[0089] Here, the reactor denoted by 300 is set to carry out a chemical reaction. For this purpose, the reactor particularly has a heat-insulated reaction vessel 10 and reaction tubes 20, and here, the multiple tube portions of the reaction tubes 20 denoted by 21 only in two cases each extend between a first zone 11' and a second zone 12' in the reaction vessel 10. The reaction tubes 20, which will be described in more detail below with reference to FIG. 2, are attached to the ceiling or support structure of the reaction vessel by a suitable suspension 13. In the lower region, the reaction vessel can particularly have a furnace (not shown). Needless to say, in any case, a plurality of reaction tubes can be provided here and thereafter.

[0090] FIG. 2 schematically shows a reactor denoted by 100 in its entirety for carrying out a chemical reaction according to an embodiment of the present invention.

[0091] The zones previously designated by 11’ and 12’ here take the form of regions 11 and 12, and the pipe portion 21 for heating the pipe portion 21 within the first region 11 can be electrically connected to the phase connections (U, V, W) of the polyphase AC power supply 50 respectively. Specific types of connections such as switches are not shown.

[0092] In the embodiment of the present invention shown here, the pipe portion 21 is integrally connected to one or more reaction pipes 20 and is conductively connected to each other in the second region 12 by a connection element 30 arranged within the reaction vessel 10. A neutral conductor can also be connected.

[0093] Therefore, in the reactor 100 shown here, (although a plurality of such reaction pipes 20 may be provided), a plurality of pipe portions 21 of the reaction pipes 20 are arranged side by side within the reaction vessel 10. The pipe portions 21 intersect with each other via a U-shaped bend 23 (only partially shown) and are connected to a supply portion 24 and an extraction portion 25.

[0094] In the first region 11, a first group of U-shaped bends 23 (lower side in the figure) are arranged side by side, and in the second region 12, a second group of U-shaped bends 23 (upper side in the figure) are arranged side by side. The second group of U-shaped bends 23 are formed in the connection element 30, and the pipe portion 21 extends from the connection element 30 in the second region 12 to the first region 11.

[0095] Within the scope of the present invention, the use of the connection element 30 is optional but advantageous. However, the embodiments of the present invention described below relate in particular to embodiments of means for supplying current to the first region 11. This is carried out by using a current supply element 41, which is shown here in a very simplified manner and only one of which is shown.

[0096] FIG. 3 schematically shows a reactor for carrying out a chemical reaction according to an embodiment of the present invention, which is shown as 200 in its entirety.

[0097] In reactor 200, in contrast here, each of the pipe portions indicated by 22 comprises a pipe portion 22 consisting of a plurality of reaction pipes 20. The pipe portions 22 are arranged side by side in a non-fluidly communicating manner within the reaction vessel 10 and are respectively connected to a supply portion 24 and an extraction portion 25. Regarding the remaining elements, explicit reference is made to the above description regarding the previous figures.

[0098] Next, within the scope of the present invention, the use of the connecting element 30 is optional but advantageous. Here too, the current supply element 41 is shown in a very simplified manner. The current supply element can have a sleeve-shaped region 49 arranged in a first region 11 around the reaction pipe 20 or the pipe portion.

[0099] FIG. 4 shows a detailed view of the first region 11 of the reactor 100, for example according to FIG. 2. In the first region 11, a current supply configuration 40 is arranged, and the reaction pipe 20 is connected to the current supply configuration. Here, the pipe portions 21 of the reaction pipe shown in cross-section merge with each other via a U-shaped bend 23.

[0100] Here, the U-shaped bend 23 is formed within a contact passage 42 having a reinforcing wall, and the contact passage is adjacent to two pipe portions 21 within the first region 11. The wall of the contact passage 42, and thus the wall of the U-shaped bend 23, is connected to the aforementioned current supply element indicated as 41 as a whole. This current supply element has a rod-shaped portion 43 that extends in the wall passage 15 through the wall 14 of the reaction vessel 10 in any case, as shown between the dashed lines here. Here, the wall passage 15 is shown with an exaggerated width. The rod-shaped portion is accommodated within the wall passage 15 so as to be movable in the longitudinal direction and is covered, for example, with a suitable heat insulating material 16.

[0101] Optionally, although not essential for the present invention, a bellows configuration 44 can be provided outside the wall 14 of the reaction vessel 10 in order to ensure an airtight seal of the reaction vessel 10 against the environment, regardless of the longitudinal mobility of the rod-shaped portion 43.

[0102] In the illustrated example, an additional rod-shaped portion 45 is adjacent to the rod-shaped portion 43, and the temperature of that portion gradually decreases as the distance from the reaction vessel 10 increases. The additional rod-shaped portion merges into the current supply pin 46, to which, for example, two busbars or strands are attached to connect the corresponding current connections of phases U, V, W, or a DC power supply or a single-phase AC power supply.

[0103] In the cracking furnace, in general called a 6-pass coil, in addition to the reaction tube 20 previously shown in FIGS. 1 and 2, which has six straight tube portions 21 having two 180° bends, namely a U-shaped bend 23 above or in the second region 12, and three 180° bends, namely a U-shaped bend 23 below or in the first region 11 (the latter having a corresponding current supply configuration), modified examples with fewer passes are also used. For example, a so-called 2-pass coil has only two straight tube portions 21 and only one 180° bend or U-shaped bend 23. When applied to electrical heating, this modified example can be regarded as a combination of a 6-pass cracking furnace (FIGS. 1 and 2) and a reforming furnace (FIG. 3 having a reaction tube without a U-shaped bend 23).

[0104] In any case, the current can be supplied at one point per reaction tube 21 at the lower (or only) U-shaped bend. In any case, the M reaction tubes can be electrically coupled to each other using a common connection element 30 with a phase shift of 360° / M. In a first alternative, a particularly large connection element 30 can be used for each coil package or for all reaction tubes 20 considered in any case. However, in a second alternative, the use of two smaller-sized connection elements 30 is also possible.

[0105] The first alternative described is shown in FIG. 5B, and the second alternative described is shown in FIG. 5C in a cross-sectional view passing through the tube portion 21, where the corresponding reaction tube 20 is shown in FIG. 5A in a view perpendicular to the figures in FIGS. 5B and 5C. For the designation of corresponding elements, refer to FIG. 1. Needless to say, on the one hand, the connecting element 30 having connections to the phase U, V, W, which probably has the arranged U-shaped bends 23, and on the other hand, the other U-shaped bends 23, are arranged in different planes corresponding to the first region 11 and the second region 12 of the reactor via a current supply configuration 40 (shown here very schematically). It should be emphasized again that the presence and arrangement of the connecting element 30 within the scope of the present invention are purely optional or arbitrary.

[0106] This concept can also be applied, in this case, corresponding to a coil or reaction tube 20 having four passages or tube portions 21 (so-called four-passage coil) with one, two, or four stub bridges or connecting elements 30. Corresponding examples are shown in FIGS. 6A and 6B, and four connecting elements 3 are shown in FIG. 6B. For better explanation, here the U-shaped bends 23 are shown by dashed lines (U-shaped bends in the second region 12 of the reactor) and solid lines (U-shaped bends in the first region 11). For clarity, the elements are only partially labeled with reference signs.

[0107] Although FIGS. 7A to 7C have already been referred to, these show further reaction tubes for use in a reactor according to an embodiment of the present invention. The reaction tubes and tube portions are only shown here when they are labeled with reference signs. The supply portion and the extraction portion can be inferred from the shown flow arrows. The current supply configuration 40, which can particularly exist several times and can be formed in the manner described above, is shown very schematically by dashed lines.

[0108] FIG. 8 shows the values of the thermal and electrical parameters in the current supply configuration 40 according to a particularly preferred embodiment of the present invention. The abscissa represents the values of the root mean square (rms) potential of the specified elements 46 (current supply pins), 43 and 45 (rod-like elements), 42 (contact passage), 21, 22 (tube portions) over time, and the ordinate represents the average temperature of the cross-section or insulating surface and the corresponding surface area. Graph 101 (solid line) shows the average temperature of the cross-sectional area, and graph 102 (dashed line) shows the surface area.

[0109] As can be seen from the figure, the average temperature 101 rises and shows a jump in the intermediate zone between the contact passage 42 and the tube portions 21, 22, particularly due to the rapid decrease in the cross-sectional area. As shown by the dashed region 101a or the dash-dotted region 102a, limited local temperature increases and cross-sectional expansions can exist in the region of the wall passage 15.

[0110] FIG. 9 shows a detailed view of the first region 11 of the reactor 200. In each case, the elements shown have already been described in connection with FIG. 4. However, in contrast to FIG. 4, here the reaction tube 20 does not have a U-shaped bend, and the tube portions 21 are arranged along a common central axis. The non-curved transition region is indicated by 23a. For example, a corresponding embodiment can be used instead of the sleeve in the reactor 200 according to FIG. 3.

[0111] Similarly here, the transition region 23a is formed in the contact passage 42 having a reinforcing wall adjacent to the two tube portions 21 in the first region 11. For details, refer to FIG. 4. Here, the wall passage 15 is also shown with an exaggerated width. Similarly here, the rod-like portion is housed in the wall passage 15 so as to be movable in the longitudinal direction and is covered, for example, with a suitable heat insulator 16. However, the wall passage 15 can have a configuration different from the figure shown here, particularly to create additional movement options. This also relates to the optional bellows configuration 44.

Claims

1. A reactor (100, 200) for performing a chemical reaction, comprising a reaction vessel (10) and one or more reaction tubes (20), wherein a large number of tube portions (21, 22) of the one or more reaction tubes (20) in each case extend between a first region (11) at a first end of the reaction vessel (10) within the reaction vessel (10) and a second region (12) at a second end of the reaction vessel (10) opposite the first end within the reaction vessel (10). For the electrical heating of the tube portions (21, 22), the tube portions (21, 22) in the first region (11) are in each case electrically connected to or can be connected to the current connections (U, V, W) of a current source (50). A current supply configuration (40) is provided in the first region (11) of the reactor (100, 200). In any case, one of the tube portions (21, 22) or, in any case, a group of one of the tube portions (21, 22) is electrically connected to the current supply configuration. Each of the current supply configurations in each case comprises one or more contact passages (42) adjacent to at least one of the tube portions (21, 22) in the first region (11). The wall of the contact passage (42) is in each case connected to a current supply element (41) having a rod-shaped portion (43) that extends in a wall passage (15) through the wall (14) of the reaction vessel (10). The rod-shaped portion (43) of the current supply element (41) is guided in a longitudinally movable manner in each respective wall passage (15) passing through the wall (14) of the reaction vessel (10) during operation. The rod-shaped portion (43) of the current supply element (41) outside the reaction vessel (10) is electrically connected to or can be connected to the current connections (U, V, W) of the current source (50) by a flexible connection element. Reactor (100, 200).

2. The number of the tube portions (21, 22) is provided such that, in any case, one of the plurality of tube portions (21, 22) or, in any case, a group of one of the plurality of tube portions (21, 22) is connected to one of the current supply configurations (40), according to the reactor (100, 200) described in Claim 1.

3. The one or more contact passages (42) are attached to the tube portions (21, 22) in a high-temperature resistant manner and are one or more components that are firmly bonded, or in any case, are formed in the form of a portion or a continuous portion of the reaction tube (21, 22), the reactor (for 100, 200) according to claim 1 or claim 2.

4. In any case, the rod-shaped portion (43) has a longitudinal extension perpendicular to the wall of the reaction vessel, and the longitudinal extension is at least twice the size of the maximum transverse extension parallel to the wall (15) of the reaction vessel (10), the reactor (100, 200) according to any one of claims 1 to 3.

5. Each of the current supply elements (41) has a free conductor cross-section that is not less than 10 square centimeters at any point between each wall passage (15) of the current supply element (41) and the point on the wall of one or more of the contact passages (42) that is closest to the wall passage (15) and is electrically contacted by each current supply element (41), the reactor (100, 200) according to any one of claims 1 to 4.

6. The current supply element (41), the contact passage (42), and the tube portions (21, 22) are formed from the same material or from materials having an electrical conductivity difference of 50% or less from each other, the reactor (100, 200) according to any one of claims 1 to 5.

7. The current supply element (41), the contact passage (42), and the tube portions (21, 22) are formed from a chromium-nickel steel alloy having 0.1 to 0.5% by weight of carbon, 20 to 50% by weight of chromium, 20 to 80% by weight of nickel, 0 to 2% by weight of niobium, 0 to 3% by weight of silicon, 0 to 5% of tungsten, and 0 to 1% by weight of other components, and the components complement each other to form a non-ferrous fraction, the reactor (100, 200) according to any one of claims 1 to 6.

8. The tube portions (21, 22) are conductively connected in whole or in groups within the reaction vessel (10) by a rigid connection element (30) or a plurality of rigid connection elements (30), the reactor (100, 200) according to any one of claims 1 to 7.

9. The one or more reaction tubes (20) have one or more U-shaped bends (23) in the first region (11) of the reaction vessel (10), and the contact path (42) in the current supply configuration (40) comprises or forms the one or more U-shaped bends (23) within the first region (11) of the reaction vessel (10). The reactor (100) according to any one of claims 1 to 8.

10. A plurality of reaction tubes (22) without U-shaped bends (23) extend within the first region (11) of the reaction vessel (10), and the contact path (42) within the current supply configuration (40) forms a straight tube portion. The reactor (200) according to any one of claims 1 to 9.

11. The reactor (100) formed as the reactor (100) for steam decomposition according to claim 9, or the reactor (200) formed as the reactor (200) for steam reforming, dry reforming, or catalytic dehydrogenation of alkanes according to claim 10.

12. The flexible connection element attached to the outside of the reaction vessel (10) is guided in a longitudinally movable manner in each wall passage (15) passing through the wall (14) of the reaction vessel (10). The reactor (100, 200) according to any one of claims 1 to 11, which is made of a material different from the rod-shaped portion (43) of the current supply element (41).

13. The wall (14) in which the rod-shaped portion (43) of the current supply element (41) is guided in a longitudinally movable manner is an intermediate wall to another space where the rod-shaped portion is in contact with the flexible connection element, and is separated by a further wall or a plurality of walls. The reactor (100, 200) according to any one of claims 1 to 12.

14. A method for carrying out a chemical reaction using a reactor (100, 200) comprising a reaction vessel (10) and one or more reaction tubes (20), wherein a number of tube portions (21, 22) of the one or more reaction tubes (20) in each case extend between a first region (11) at a first end of the reaction vessel (10) within the reaction vessel (10) and a second region (12) at a second end of the reaction vessel (10) opposite the first end within the reaction vessel (10). For heating the tube portions (21, 22), the tube portions (21, 22) within the first region (11) are each electrically connected to a current connection (U, V, W) of a current source (50). The reactor (100, 200) is used, where a current supply configuration (40) is provided in the first region (11) of the reactor (100, 200). In each case, one of the tube portions (21, 22) or in each case a group of one of the tube portions (21, 22) is electrically connected to the current supply configuration. Each of the current supply configurations in each case comprises one or more contact passages (42) adjacent to at least one of the tube portions (21, 22) within the first region (11). The walls of the contact passages (42) in each case are connected to a current supply element (41) having a rod-shaped portion (43) that extends in a wall passage (15) through the wall (14) of the reaction vessel (10). The rod-shaped portion (43) of the current supply element (41) is guided in a longitudinally movable manner within each wall passage (15) passing through the wall (14) of the reaction vessel (10) during operation. The rod-shaped portion (43) of the current supply element (41) outside the reaction vessel (10) is electrically connected to the current connection (U, V, W) of the current source (50) by a flexible connection element.

15. The method according to claim 14, wherein the reactor according to any one of claims 1 to 13 is used.

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