Reactors and methods for carrying out chemical reactions

Abstract

A reactor (100, 200) for carrying out a chemical reaction comprises a reactor vessel (10) and one or more reaction tubes (20), in each case a number of tube sections (21, 22) of the one or more reaction tubes (20) passing between a first region (11) and a second region (12) in the reactor vessel (10), the tube sections in the first region (11) for electrical heating of the tube sections (21, 22) being electrically connected to phase junctions of a polyphase AC power source (50). The invention provides that the tube sections (21, 22) in the second region (12) are electrically conductively connected to one another as a whole by a single rigid connection element (30) or in groups by a plurality of rigid connection elements (30), which are integrally connected to the one or more reaction tubes (20) and disposed within the reactor vessel (10). A corresponding method is also the subject of the 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 and react catalytically or non-catalytically in the reaction tubes. Heating, in particular, serves to overcome the activation energy required for the ongoing chemical reaction. The reaction can proceed endothermically as a whole or exothermically after overcoming the activation energy. The present invention relates in particular to strong endothermic reactions.

[0003] Examples of such processes are various reforming processes such as steam cracking and, in particular, steam reforming, dry reforming (carbon dioxide reforming), mixed reforming processes, dehydrogenation processes of alkanes, etc. During steam cracking, the reaction tubes can pass through the reactor in the form of coils having an inversion point within the reactor, while tubes passing through reactors without an inversion point are usually used in steam reforming.

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

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

[0006] However, as described in DE102015004121A1 (and similarly EP3075704A1), the demand for synthesis gas and hydrogen produced with or without reduced local carbon dioxide emissions is increasing, for example. However, this demand cannot be met by processes that use combustion reactors, typically by burning fossil energy media. Other processes are excluded for reasons such as high cost. The same applies to the supply of olefins and / or other hydrocarbons by the steam cracking or dehydrogenation of alkanes. In such cases, processes that release at least less carbon dioxide in situ are desirable.

[0007] Against this backdrop, the aforementioned DE102015004121A1 proposes the electrical heating of the reactor for steam reforming in addition to combustion. In this case, one or more voltage sources are used to supply a three-phase AC voltage to three external conductors. Each external conductor is connected to a reaction tube. A star circuit is formed where a star point is realized by a collector to which the pipeline is open and the reaction tube is electrically connected. In this way, the collector remains ideally at zero potential. The collector is positioned below and outside the combustion chamber relative to the vertical, and preferably extends laterally or horizontally with respect to the reactor tube.

[0008] The corresponding electrical heating of the reactor can be problematic in reactors where the type of collector described is not present, for example, in reactors where the reaction tube has a reversal point within the reactor that should be connected to a star point, as in the case of WO2015 / 197181A1. Due to the high current flow and temperature within the reactor, it is difficult to find a solution for electrically connecting the reactor tube at the star point with a sufficient current transition value in order to reduce excessive power loss and ensure that the current flow is uniformly distributed and therefore the star point is at zero potential.

[0009] US2014 / 02338523A1 relates to a device for heating a pipeline system for molten salt, comprising at least two pipelines through which electrical resistance heating elements extend, wherein a potential close to ground potential is set at at least one end of each electrical resistance heating element, and the electrical resistance heating elements are connected away from the electrical resistance heating elements to a junction of a DC power supply, or in either case to a phase of an n-phase AC power supply.

[0010] WO2015 / 069762A2 discloses a chemical reactor system comprising a chemical reactor having an inlet and a manifold in fluid communication with the inlet, wherein the manifold comprises a manifold housing, the manifold housing having at least one additional component which may comprise a heater that defines a manifold chamber and is in thermal communication with the manifold chamber and cavity, the manifold housing defines a cavity and a seal is provided in a particular arrangement.

[0011] A fixed-bed reactor disclosed in US2015 / 010467A1 comprises an inlet path for raw material gases for a catalytic reaction and an outlet path for reformed gases, a catalytic reactor vessel connected to the inlet and outlet paths and containing a catalyst, a catalyst holder having aeration properties and holding the catalyst, and a drive mechanism for moving the catalyst up and down by moving the catalyst holder up and down. US6296814B1 discloses a fuel reformer that serves to produce hydrogen enrichment process fuel from raw fuel. The catalyst tube arrangement preferably comprises a plurality of catalyst tubes arranged in a hexagonal arrangement. The housing includes hexagonal insulation inside to ensure uniform heating of the catalyst tubes. The diameter of the tubes is sized so that the distance between adjacent tubes in the arrangement is minimized for efficient heat transfer.

[0012] Therefore, an object of the present invention is to improve an electrically heated reactor for carrying out a chemical reaction. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] DE102015004121A1 publication [Patent Document 2] EP3075704A1 publication [Patent Document 3] WO2015 / 197181A1 publication [Patent Document 4] US2014 / 02338523A1 publication [Patent Document 5] WO2015 / 069762A2 publication [Patent Document 6] US2015 / 010467A1 publication [Patent Document 7] US6296814B1 publication [Non-patent literature]

[0014] [Non-Patent Document 1] Ullman's Encyclopedia of Industrial Chemistry, "Ethylene," DOI:10.1002 / 14356007.a10_045.pub2, April 15, 2009. [Non-Patent Document 2] Ullman Encyclopedia of Industrial Chemistry, "Gas Production," DOI:10.1002 / 14356007.a12_169.pub2, December 15, 2006. [Non-Patent Document 3] Ullman's Encyclopedia of Industrial Chemistry, "Propene", DOI:10.1002 / 14356007.a22_211, June 15, 2000. [Overview of the project]

[0015] Against this backdrop, the present invention proposes a reactor and method for carrying out a chemical reaction in accordance with the preamble of the independent claim. Embodiments are the subject of the dependent claims and the following description.

[0016] In the concept of a nearly partially electrified furnace, which forms the basis of the present invention (the term “furnace” is generally understood to refer to the corresponding reactor or at least its insulated reaction space), at least one of the reaction tubes, or its corresponding tube portion (hereinafter also abbreviated as “tube”) itself, is used as an electrical resistor for generating heat. This approach has the advantages of being more efficient and achieving a higher heat flux density compared to indirect heating by an external electrical heating element. The scope of the present invention also includes the possibility of providing part of the total heat output in the furnace by burning other energy media, such as fossil energy media like natural gas, or even energy media such as so-called bionatural gas or biomethane.

[0017] Therefore, even if we discuss electrical heating here, we do not rule out the existence of additional non-electric heating. In particular, the contributions of electrical and non-electric heating change over time, for example, as a function of the supply and price of electricity or the supply and price of non-electric energy media, as mentioned above.

[0018] The current is supplied to a directly heated reaction tube via M separately connected phases. The energized reaction tube connected to the M phases also needs to be electrically connected to the star point. The number of phases M is particularly 3, corresponding to the number of phases in a conventional three-phase current source or network. However, in principle, the present invention is not limited to the use of three phases and can be used with more phases, such as 4, 5, 6, 7, or 8 phases. Multiples of 3, such as 6, 9, 12, etc., are particularly preferred. In this case, the phase offset is particularly 360° / M, i.e., 120° in the case of three-phase current.

[0019] Equipotentialization between phases is achieved by a star circuit at the star point, eliminating the need for electrical insulation of connected pipelines. This represents a special advantage of such a reactor concept, because, in particular, the damage to metal reaction tubes used for insulating specific parts is undesirable, as high temperatures are used and the costs of materials and construction are high.

[0020] In the language of the claims, the present invention relates to a reactor for carrying out a chemical reaction, the reactor having a reactor vessel (i.e., a thermally insulated or at least partially thermally insulated region) and one or more reaction tubes, in any case some tube portions of the one or more reaction tubes passing between a first region and a second region within the reactor vessel and through an intermediate region between the first region and the second region, and for electrical heating of the tube portions, the tube portions in any case being electrically connected or connectable, in the first region, to a phase junction (the "external conductor") of a polyphase AC power supply, for example by means of busbars and connection strips. The switching device can in particular be installed on the primary side of the transformer system employed, since there is a higher voltage and a lower current.

[0021] As described above, the AC voltage is in any case supplied via the phase junction, and the AC voltage of the phase junction 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 serve as the AC power source. The tube portions form a star circuit, in which the ends opposite the current source, i.e., in the second region, are conductively connected to each other.

[0022] In the intermediate region, the tube portions in particular pass through the reactor vessel freely, i.e., without mechanical support, without electrical contact, and / or without fluid or purely mechanical cross-connections. The tube portions in particular extend substantially or completely straight in the intermediate region, where "substantially straight" is to be understood to mean that there is an angular deviation of less than 10° or 5°.

[0023] According to the present invention, the tubular sections are integrally connected to one or more reaction tubes and electrically connected to each other throughout the entire second region by a single rigid connecting element ("star bridge") located inside the reactor vessel, or this connection is achieved by a group of multiple such rigid connecting elements. One or more connecting elements fluid-couple each electrically connected tubular section to each other in pairs. In this case, "in pairs" should be understood to mean that at most one tubular section entering the connecting element is fluid-coupled to at most one other tubular section entering (or, in terms of flow direction, leaving the connecting element), or in other words, in either case, the tubular sections fluid-communicated in pairs via the connecting element move, or are designed to move, substantially the same amount of fluid per unit time. In this particular context, "substantially the same amount of fluid" should be understood to mean a difference of 10%, 5%, or 1% or less. Therefore, one or more connecting elements connect the connected tubular sections in a non-collection and non-distribution manner, in contrast to collectors known from the prior art and located outside the reactor.

[0024] The solution proposed by this invention has the advantage of enabling maximum equipotentialization through one or more star bridges formed by one or more junction elements. This results in nearly complete release from the potential or a significant reduction in return current through the connected neutral conductor. As a result, current dissipation through the header junction to other parts of the process system is minimized, achieving a high level of shock protection.

[0025] A further advantage of the one or more joining elements proposed by the present invention compared to one or more collectors positioned outside the reactor vessel and optionally similarly providing an electrical connection at the star point is the more clearly defined distance of the electrical heat input (for example, this is not the case with the star point of the collector, as the electrically heated tubular portion must be led from a warmer internal space to a cooler external space, here) and the spatially very uniform external thermal boundary conditions of the electrically heated tubular portion (there is no electrical heating in the adiabatic passage through the reactor vessel to the collector operating at a lower temperature). This results in process engineering advantages, such as the avoidance of excessive coke formation that would be expected in a heated and externally insulated passage.

[0026] Since the underlying reaction requires high temperatures, the electrical connection in the second region must be achieved in a high-temperature range of approximately 900°C, for example, for steam decomposition. This is possible by the measures proposed in accordance with the present invention, by selecting appropriate materials. At the same time, this connection is intended to have high conductivity and high mechanical stability and reliability at high temperatures. Failure of the electrical connection directly prevents equipotentialization, resulting in the flow of undesirable currents through system components, leading to an immediate safety-related shutdown of the system. The present invention offers advantages over the prior art by avoiding such situations.

[0027] In conventional burner-heated reaction tubes for steam decomposition, there is no need for joints between the U-shaped bends of the reaction tubes placed within the reactor; instead, they are suspended with a certain degree of freedom of movement. In particular, the lower U-shaped bend can hang freely within the reactor vessel, while the upper U-shaped bend has a somewhat smaller degree of freedom of movement. This degree of freedom of movement is advantageous for the mechanical behavior of the reaction tubes, which is primarily governed by the thermal expansion of the tubes. Therefore, the present invention is based on the discovery that rigid joints, which are considered undesirable in the context described above, offer advantages that outweigh the potential disadvantages resulting from the lack of freedom of movement.

[0028] When implementing a star circuit in a reaction tube, it is necessary to provide conductive cross-connections of appropriate dimensions between tube sections, while also providing a structure that can withstand stresses mainly arising from a high coefficient of thermal expansion.

[0029] Conventional technologies have not yet made it possible to flexibly realize the necessary electrical connections between U-shaped bends (star bridges) within this temperature range. No materials possess sufficient long-term temperature stability or sufficient (e.g., weldable) processability to create flexible electrical connections. Furthermore, there are very few joining technologies available in this application area for intermetallic transitions.

[0030] Therefore, the present invention is based on the remarkable discovery that, despite the lack of degrees of freedom of motion, a rigid starbridge joint with sufficient cross-sectional area for the necessary equipotentialization can absorb the mechanical stresses generated during high-temperature use over the operating time relevant to actual applications. Since the currents flowing through it are in the kiloampere range, considerable design effort is required.

[0031] The present invention will first be described below with reference to reaction tubes and reactors used for steam decomposition. However, as will be described later, the present invention can also be used with other types of reactors, as will be discussed later. In general, as stated above, the reactors proposed by the present invention can be used to carry out any endothermic chemical reaction.

[0032] In a first advance of the present invention, the reactor can be used in particular with so-called two-passage coils. These coils have two tubular sections in the reactor vessel, which transition to each other via (exactly) a single U-shaped bend, and thus essentially have an (elongated) U shape. The sections that enter and exit the reactor vessel, in particular the sections that enter the heated tubular section seamlessly or without flow-related transitions, are hereby referred to as the “feed section” and the “extract section” (see also the reaction tubes described below). There are always multiple such reaction tubes.

[0033] Therefore, in this development, the reactor can be designed such that two tube sections of a plurality of reaction tubes are arranged at least partially side by side within the reactor vessel, each tube section having its own, in any case the two tube sections of the plurality of reaction tubes pass each other in the first region via a U-bend. In particular, as mentioned above, in any case one of the two tube sections in the second region is connected to the feed section, and in any case the other of the two tube sections in the second section is connected to the extraction section.

[0034] In the advancements of the present invention described above, in one variation, one of each of the two tube sections of the plurality of reaction tubes in the second region is connected to a first joining element of the joining element, and the other of each of the two tube sections of the plurality of reaction tubes in the second region is connected to a second joining element of the joining element. In this way, in either case, multiple potentialless star points can be formed, which has the advantage of reducing mechanical stress, particularly due to thermal expansion, because the flexibility of the narrower, plurality of joining elements is increased.

[0035] In the advancements of the present invention described above, in another variation, in contrast, in both cases, both tube sections of the multiple reaction tubes, and in particular all tube sections in the second region, are connected to a common junction element. In this way, a potentialless star point is formed overall, which has the advantage of eliminating, for example, further intermediate junctions.

[0036] The advances of the present invention described above can also be adapted to a reaction tube having two feed sections and one extraction section. In such a reaction tube, the two feed sections are, in both cases, connected to a single tube section. The extraction section is also connected to a tube section. The tube section connected to the feed sections typically transitions to the tube section connected to the extraction section at a Y-shaped junction. Not only the tube section connected to the feed sections, but also the U-shaped bends connected to the extraction section may each have one or more U-shaped bends, or none at all.

[0037] For example, a reaction tube like the one shown in Figure 10C can be used. In these reaction tubes, the tube section connected to the supply section does not have a U-shaped bend, but the tube section connected to the extraction section does have a U-shaped bend.

[0038] In this case, in particular, the tube portions formed by the tube portions connected to the supply portion may be connected to the first joining element of the joining element in the second region, and the tube portions formed by the tube portions connected to the extraction portion may be connected to the second joining element of the joining element. In this way, a plurality of potentialless star points can be formed as described above, having the advantages already explained above.

[0039] However, instead, as another variation, the tubular sections formed by the tubular sections connected to the supply section, the tubular sections formed by the tubular sections connected to the extraction section, and especially all the tubular sections in the second zone, are connected to a common junction element. In this way, a potentialless star point is formed overall, which has the advantage of eliminating, for example, further intermediate junctions.

[0040] However, reaction tubes like the one shown in Figure 10B may also be used. In these reaction tubes, each tube section connected to the supply section has a U-shaped bend, and the tube section connected to the extraction section has two U-shaped bends.

[0041] It is even possible to use reaction tubes as shown in Figure 10A. In these reaction tubes, the tube section connected to the supply section has three U-shaped bends, and the tube section connected to the extraction section has two U-shaped bends.

[0042] In the last two cases, any of the tubular sections in the second region can be connected to different connecting elements or to a common connecting element, thereby achieving the same advantages already described above. Numerous further configurations are also possible, having reaction tubes with branching or Y-shapes.

[0043] However, instead, and here again as another variation, the tubular sections formed by the tubular sections connected to the supply section, the tubular sections formed by the tubular sections connected to the extraction section, and especially all the tubular sections in the second zone, are connected to a common junction element. In this way, a potentialless star point is formed overall, which has the advantage of eliminating, for example, further intermediate junctions.

[0044] However, in addition to the advancements described above, particularly with respect to two-passage coils, advancements suitable for use in so-called four-passage coils can also be used. These have four substantially straight tube sections. However, configurations with a larger even number of straight tube sections are also possible.

[0045] In more general terms, a reactor designed to correspond comprises one or more reaction tubes, each of which has an even number of four or more tube sections connected in series with each other via a number of U-bends, the number of U-bends being one less than the number of tube sections connected in series with each other via U-bends, and the U-bends being arranged alternately in the first and second regions, starting with the first U-bend in the first region.

[0046] Here, “U-bend” is understood to mean a pipe section or pipe component having a pipe bend that is partially circular or partially elliptical, and especially semicircular or semielliptical. The starting and ending points have cross-sections that are adjacent to each other, in particular, in one plane.

[0047] In the first example where a four-passage coil is used, the tubular section mentioned includes the first, second, third, and fourth tubular sections of the reaction tube, or in any case, the first tubular section enters the second tubular section through the first U-bend, the second tubular section enters the third tubular section through the second U-bend, and the third tubular section enters the fourth tubular section through the third U-bend. The first tubular section is connected to the feed section, particularly in the second zone, and the fourth tubular section is connected to the extraction section, particularly in the second zone. The first and third curved sections are located in the first region, and the second curved section is located in the second region. These descriptions also apply to six tubular sections, where the first, third, and fifth curved sections are then located in the first region, and the second and fourth curved sections are located in the second region.

[0048] In the development described above, having one or more U-shaped bends, the U-shaped bends located in the second region can be formed on the joint element, and the tubular portion can be extended from the joint element in the first region to the second region.

[0049] In this case, the joining element can be cast onto a formed tubular portion that is previously joined (e.g., welded to) the U-bend of the second region, or it can be connected to the tubular portion (e.g., by bending). In other words, the reaction tube is pre-formed with corresponding tubular portions and one or more U-bends, and then encapsulated in the corresponding region. This simplifies the design of the reaction tube.

[0050] However, it is also possible to form a U-shaped bend in a second region within the joint element (for example, by casting) and weld the tubular section to the joint element. In this way, the corresponding reactor can be manufactured in a simplified modular manner, requiring only the welding of straight tubular sections. Using the joint element as a standard component reduces manufacturing costs.

[0051] To summarize again, the corresponding reactor may have any reaction tube known from the prior art, particularly as described in the above article "Ethylene" in the Ullman Encyclopedia of Industrial Chemistry. For example, the corresponding reaction tubes are designated as SC-1, SC-2, SC-4, USC-U, SuperU, USC-W, FFS, GK-1, GK-6, SMK, Pyrocrack 1-1, Pyrocrack 2-2, or Pyrocrack 4-2.

[0052] As described above, the corresponding reactor can be designed specifically as a reactor for steam decomposition, in particular, by selecting heat-resistant materials and structuring the reaction tubes.

[0053] However, in further alternatives, each tubular section may comprise a tubular section consisting of multiple reaction tubes, and the tubular sections within the reactor vessel are arranged at least partially side by side in a non-fluid communication manner, and in any case are connected to a supply section (for fluid) in a first region and an extraction section (for fluid) in a second region. The extraction section extends in the same direction as the tubular section in particular, or does not produce a fluid flow deflected by more than 15° with respect to the fluid flow in the connected tubular section. The supply section and the extraction section are formed integrally in particular, i.e., in particular, in the form of the same tube. The reaction tubes are designed here in particular without U-bends. In this way, a reactor suitable for, for example, carrying out steam reforming is made. This can also be achieved in particular by providing the reaction tubes with a suitable catalyst. In this embodiment, the joining element in the second region is cast in particular on the reaction tubes. In particular, the joining element can surround the reaction tubes like a cuff.

[0054] In all the cases described above, the joint elements and tube portions may be formed from the same material, or from materials whose conductivity (in terms of material constants, as is common in this art) differs by 50%, 30%, 10%, or, more favorably, is identical. For example, the joint elements and tube portions may also be formed from steel of the same steel grade. The use of identical or closely related materials can facilitate the integrated design of the joint elements and tube portions, for example, by casting or welding.

[0055] In all cases, the number of intermetallic joints (e.g., welds or solder joints) can be reduced or even eliminated entirely by forming the joint element from as few individual parts as possible. This can increase mechanical stability and reliability. In further embodiments, the joint element can be implemented as a single casting, or, as described above, a portion of the process carry pipe can be cast into the joint element, and / or a portion of the process carry pipe can be formed as an integral component of the corresponding casting.

[0056] Intermetallic joints or metallic transitions that can be reduced within the scope of this invention may result in localized changes in electrical resistance, and therefore, hot spots. Hot spots, on the other hand, can lead to a shortened service life due to increased local temperature or peaks in mechanical stress due to steep local temperature gradients. This is avoided within the scope of this invention.

[0057] One-piece joint elements provide mechanical stability, reliability, and a reduction in the number of individual components. As mentioned above, a star bridge failure can lead to a safety-critical situation, so high mechanical stability of the star bridge is desirable. By embodiments described in view of the present invention, the principle of a reaction tube resistively heated by multiphase AC in a star circuit is technically feasible, particularly in high-temperature ranges above 500°C, above 600°C, above 700°C, or above 800°C.

[0058] Given the same conductivity, the desired increased conductance of a junction element can be achieved by increasing the cross-sectional area according to R = ρ(l / A), where R is the resistance of the conductor expressed in ohms, ρ is the specific resistivity, i.e., the reciprocal of the conductivity, l is the length of the conductor, and A is its cross-sectional area.

[0059] A possible material for the reaction tube and therefore the joining element is a highly alloyed chromium-nickel steel, such as that used in firing furnaces. Advantageously, chromium-nickel steel is an alloy with high oxidation or scaling resistance and high carburizing resistance.

[0060] For example, the alloy may have 0.1–0.5 wt% carbon, 20–50 wt% chromium, 20–80 wt% nickel, 0–2 wt% niobium, 0–3 wt% silicon, 0–5 wt% tungsten, and 0–1 wt% of other components, where these components complement each other to form a non-ferrous fraction. The corresponding alloy may also contain, for example, 20–40 wt% chromium, 20–50 wt% nickel, 0–10 wt% silicon, 0–10 wt% aluminum, and 0–4 wt% niobium.

[0061] For example, the standard names 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, which conform to DIN EN 10027 Part 1, "Materials," may be used. These have been proven to be particularly suitable for use at high temperatures.

[0062] In further embodiments, the joint element can be insulated from the high-temperature environment to reduce thermal stress caused by steep temperature gradients. For example, a radiation shield can be placed inside the reactor vessel, which shields the joint element from excessive heat input from the tubular portion.

[0063] In further embodiments, part of the joining element may be made of the reaction tube material, and part of the joining element (or further parts) may be made of a material having a higher specific conductivity. In this case, a solid intermetallic joint (e.g., a welded seam) is not necessarily provided. Electrical contact can also be ensured by different thermal expansions. For example, a casting made of one of the previously specified materials can be inserted into a matching molybdenum U profile.

[0064] Therefore, in this development, the claims language stipulates that the bonding element is at least partially surrounded by a conductive element made of, or formed from, a material rich in molybdenum, tungsten, tantalum, niobium, and / or chromium. In particular, this material has a higher specific conductivity than the material from which the bonding element is formed. As a result, equipotentialization at the star point can be greatly improved, or the corresponding bonding element can be made lighter accordingly.

[0065] The present invention also relates to a method for carrying out a chemical reaction using a reactor having a reactor vessel and one or more reaction tubes, wherein multiple tube portions of the one or more reaction tubes in any case pass between a first region and a second region within the reactor vessel, and the first region for heating the tube portions in any case is electrically connected to a phase junction of a multiphase AC power supply.

[0066] According to the present invention, a reactor is used, and the tubular portions in the second region are electrically connected to one or more reaction tubes by connecting elements and are arranged within the reactor vessel.

[0067] For further features and advantages of the corresponding method in which the reactor according to one of the previously described advances of the present invention is advantageously used, please refer to the above description.

[0068] The present invention will be further described below with reference to the accompanying drawings, which illustrate the progress of the invention with reference to and in comparison to the prior art. [Brief explanation of the drawing]

[0069] [Figure 1] Figure 1 is a schematic diagram showing a reactor for carrying out a chemical reaction according to an advancement not of the present invention. [Figure 2] Figure 2 is a schematic diagram showing a reactor for carrying out a chemical reaction according to the progress of the present invention. [Figure 3] Figure 3 is a schematic diagram showing a reactor for carrying out a chemical reaction in accordance with further developments of the present invention. [Figure 4] Figure 4 is a schematic diagram showing a bonding element for use in a reactor as the present invention progresses. [Figure 5] Figure 5 is a schematic diagram showing a bonding element for use in a reactor as the present invention progresses. [Figure 6] Figure 6 is a schematic diagram showing a cross-section of a bonding element for use in a reactor as the present invention progresses. [Figure 7] Figure 7 shows a resistor in a configuration for use in a reactor, according to the progress of the present invention. [Figure 8A] Figure 8A shows a reaction tube and corresponding configuration for use in a reactor as the present invention progresses. [Figure 8B] Figure 8B shows a reaction tube and corresponding configuration for use in a reactor as the present invention progresses. [Figure 8C] Figure 8C shows a reaction tube and corresponding configuration for use in a reactor as the present invention progresses. [Figure 9A]Figure 9A shows a reaction tube and corresponding configuration for use in a reactor as the present invention progresses. [Figure 9B] Figure 9B shows a reaction tube and corresponding configuration for use in a reactor as the present invention progresses. [Figure 10A] Figure 10A shows a further reaction tube for use in a reactor as the present invention progresses. [Figure 10B] Figure 10B shows a further reaction tube for use in a reactor as the present invention progresses. [Figure 10C] Figure 10C shows a further reaction tube for use in a reactor as the present invention progresses. [Modes for carrying out the invention]

[0070] In the following diagrams, elements that correspond to each other functionally or structurally are indicated by the same reference numerals and are not repeated for clarity. Where a component of a device is described below, the corresponding description is in all cases related to the way it is performed, and vice versa.

[0071] Figure 1 schematically shows a reactor for carrying out a chemical reaction according to an advancement not of the present invention.

[0072] Here, the reactor indicated by 300 is set up to carry out a chemical reaction. For this purpose, the reactor has, in particular, an insulated reactor vessel 10 and reaction tubes 20, and in two cases, several tubular sections of the reaction tubes 20 indicated by 21 pass between a first zone 11' and a second zone 12' in the reactor vessel 10, respectively. The reaction tubes 20, which will be described in more detail below with reference to Figure 2, are attached to the ceiling or support structure of the reactor vessel by appropriate suspensions 13. In the lower region, the reactor vessel may have, in particular, a furnace (not shown). Needless to say, in either case, there may be multiple reaction tubes here and thereafter.

[0073] Figure 2 schematically shows a reactor for carrying out a chemical reaction according to the progress of the present invention, with the whole represented as 100.

[0074] Here, the zones previously designated as 11' and 12' take the form of regions 11 and 12, and the tube portion 21 for heating the tube portion 21 in the first region 11 can in either case be electrically connected to the phase junctions U, V, and W of the multiphase AC power supply 50. The corresponding phase junctions can also be designated by other abbreviations, not just L1, L2, L3 or A, B, C, according to convention. Certain types of connections, not just switches, are not shown.

[0075] In the advancements of the present invention shown herein, the tubular portion 21 is integrally connected to one or more reaction tubes 20 and electrically connected to one another in a second region 12 by a connecting element 30 located within the reactor vessel 10. Neutral conductors can also be connected.

[0076] Therefore, in the reactor 100 shown herein, multiple tube sections 21 of a reaction tube 20 (however, multiple such reaction tubes 20 may be provided) are arranged side by side in the reactor vessel 10. The tube sections 21 transition to one another via U-shaped bends 23 (only partially shown) and are connected to a supply section 24 and an extraction section 25.

[0077] The first group of U-shaped bends 23 (bottom in the figure) are arranged side by side in the first region 11, and the second group of U-shaped bends 23 (top in the figure) are arranged side by side in the second region 12. The second group of U-shaped bends 23 are formed on the joint element 30, and the pipe portion 21 extends from the joint element 30 in the second region 12 to the first region 11.

[0078] Figure 3 schematically shows a reactor, shown as a whole at 200, for carrying out a chemical reaction according to the progress of the present invention.

[0079] In reactor 200, the tubular section, here shown as 22 in contrast, comprises in both cases a tubular section 22 consisting of multiple reaction tubes 20, which are arranged side by side in the reactor vessel 10 in a non-fluid communication manner and are in both cases connected to the supply section 24 and the extraction section 25. For the remaining elements, the above description relating to the preceding figures is explicitly referenced.

[0080] Figure 4 schematically shows a bonding element 30 for use in a reactor according to the advancements of the present invention, for example, in the reactor 100 shown in Figure 2.

[0081] The elements shown in the figures have essentially already been described above, so refer specifically to Figures 1 and 2 to explicitly refer to the above description. The suspension 13 is not shown here but is additionally shown in the form of an asterisk symbol, and in the development shown here, for example, the tubular portion 21 and U-bend portion 23 formed in the joint element 30 during casting are welded thereto.

[0082] Figure 5 schematically illustrates a bonding element 30 for use in a reactor as the invention progresses, as not previously shown.

[0083] As shown herein, within the scope of the present invention, a star-shaped arrangement (in a geometrical view) of the tubular sections 21 can also be made, with the joint element 30 at the center of this arrangement. Needless to say, multiple such star-shaped arrangements can also be provided, for example, side by side or stacked on top of each other. Unlike the arrangement shown in Figure 5, the tubular sections can also extend, for example, upward or downward from the drawing plane.

[0084] Figure 6 schematically shows a cross-section of the joining element 30 for use in a reactor according to the progress of the present invention, again, for example, in reactor 100 according to Figure 2.

[0085] As illustrated here, the joint element 30 is made from a previously described material having suitable conductivity and is at least partially surrounded by a conductive element 31, for example, in the form of a U-profile. The joint element 30 can be formed from, for example, high-alloy chromium-nickel steel, or from, for example, the ET45 micromaterial described above. The conductive element 31 improves equipotentialization, as already described.

[0086] Figure 7 shows a resistor in a configuration for use in a reactor according to the progress of the present invention, or, here, advantageously, for achieving a resistive relationship between the elements. This configuration is particularly suitable for use in reactor 100 according to Figure 2.

[0087] The resistors in the junction element 30 are denoted by Rb,i in Figure 7, Rh,i in the supply portion 24 and extraction portion 25, and Rn,i in the suspension 13. As shown in Figure 7 itself, advantageously, Rh,i >> Rn,i >> Rb,i holds true.

[0088] In a decomposition furnace, in addition to the reaction tube 20 previously shown in Figures 1 and 2, which is generally called a 6-passage coil and has six straight tube sections 21 having two 180° bends, i.e., U-bends 23 above or in the second region 12, and three 180° bends, i.e., U-bends 23 below or in the first region 11, variations with fewer passages can also be used. For example, a so-called 2-passage coil has only two straight tube sections 21 and only one 180° bend or U-bend 23. When adapted for electric heating, this variation can be considered a combination of a 6-passage decomposition furnace (Figures 1 and 2) and a reforming furnace (Figure 3, with a reaction tube without U-bends 23).

[0089] The flow can be supplied at one point for each reaction tube 21 at the lower (or sole) U-bend. In either case, the M reaction tubes can be electrically coupled to one another using a common junction element 30 with a phase shift of 360° / M. In the first alternative, a particularly large junction element 30 can be used for each coil package or for all reaction tubes 20 considered. However, in the second alternative, it is also possible to use two smaller sized junction elements 30.

[0090] The first alternative, which has just been described, is shown in Figure 9B, and the second alternative, which has just been described, is shown in Figure 9C in a cross-sectional view through the tube section 21, and the corresponding reaction tube 20 is shown in Figure 9A in a field of view perpendicular to the field of view in Figures 9B and 9C. For the designation of the corresponding elements, Figure 1 is referenced. Needless to say, the joint element 30, on the one hand where the U-bend 23 may be located, and the other U-bend 23 having joints to phases U, V, and W on the other hand, are located in different planes corresponding to the first region 11 and the second region 12 of the reactor.

[0091] This concept can also be applied in correspondence to a coil or reaction tube 20 having four passages or tubular sections 21 (so-called four-passage coils) with one, two, or four star bridges or connecting elements 30 in this case. Corresponding examples are shown in Figures 9A and 9B, with four connecting elements shown in Figure 9B. For better explanation, the U-bends 23 are shown here with dashed lines (U-bends in the second region 12 of the reactor) and undashed lines (U-bends in the first region 11). For clarity, the elements are given reference numbers only in part.

[0092] As already shown in Figures 10A and 10B, these depict further reaction tubes for use in reactors as the invention progresses. Here, reaction tubes and tube sections are numbered only in some cases. The feed section and extraction section can be inferred from the flow arrows shown.

Claims

1. A reactor (100, 200) for carrying out a chemical reaction, comprising a reactor vessel (10) and one or more reaction tubes (20), wherein a number of tube sections (21, 22) of the one or more reaction tubes (20) are arranged side by side within the reactor vessel (10), passing between a first region (11) and a second region (12) within the reactor vessel (10), and for the electrical heating of the tube sections (21, 22), the tube sections (21, 22) in the first region (11) are electrically connected or connectable to a phase junction of a multiphase AC power supply (50) having a phase offset of 360° / M, and the reactor (100, 200) uses the tube sections (21, 22) as electrical resistors to generate heat. Reactor (100, 200), characterized in that the tubular portions (21, 22) in the second region (12) are electrically connected to one another by a single rigid connecting element (30) or electrically connected in groups by a plurality of rigid connecting elements (30), the single rigid connecting element (30) or the plurality of rigid connecting elements (30) are integrally connected to one or more reaction tubes (20) and arranged in the reactor vessel (10) as one or more star bridges configured to provide equipotentiality between M phases at a star point, and the single rigid connecting element (30) or the plurality of rigid connecting elements (30) are configured to operate when heated to a temperature higher than 700°C.

2. The reactor (100, 200) according to claim 1, wherein the chemical reaction is an endothermic chemical reaction.

3. The reactor according to claim 1 or 2, wherein the tube portion (21) comprises two tube portions (21) of one or more reaction tubes (20) arranged at least partially side by side in the reactor vessel (10), and the two tube portions (21) of each of the one or more reaction tubes (20) transition from one another in the first region (11) via a U-bend (23).

4. The reactor according to claim 3, wherein in each case, of the two tube portions (21) of one or more reaction tubes (20), one tube portion (21) is connected to a first rigid joint element (30) or a plurality of first rigid joint elements (30), and the other tube portion (21) of each of the two tube portions (21) of the plurality of reaction tubes (20) is connected to a second rigid joint element (30) or a plurality of second rigid joint elements (30).

5. The reactor according to claim 3, wherein the two tube portions (21) of the plurality of reaction tubes (20) are connected to one of the rigid joint elements (30).

6. The reactor (100) according to claim 1 or 2, wherein the tube portion (21) is an even number of four or more tube portions (21) of the reaction tube (20), or in either case, one of the plurality of reaction tubes (20) is connected in series with respect to a plurality of U-bends (23), the number of U-bends (23) is one less than the number of tube portions (21) connected in series with respect to a plurality of U-bends (23), and the U-bends (23) are arranged alternately in the first region (11) and the second region (12).

7. The reactor (100) according to claim 6, wherein at least one of the U-shaped bends (23) located in the second region (12) is formed on the rigid joint element (30), and the tubular portion (21) extends from the rigid joint element (30) in the second region (12) to the first region (11).

8. The reactor (100) according to claim 6 or 7, wherein the rigid joint element (30) has at least one U-shaped bend (23) in the second region cast on the tubular portion (21) or connected to the tubular portion (21).

9. The reactor (100) according to claim 6 or 7, wherein at least one of the U-shaped bends (23) in the second region (12) is formed on the rigid joint element (30), and the tubular portion (21) is welded to the rigid joint element (30).

10. The reactor (100) for carrying out a chemical reaction is designed as a reactor for vapor decomposition, according to any one of claims 1 to 9.

11. The reactor (200) according to claim 1, wherein the tube portion (22) comprises a plurality of tube portions (22) of reaction tubes (20), the tube portions (22) are arranged side by side in the reactor vessel (10) without being fluidly connected, and are connected to a supply portion (24) in the first region and an extraction portion (25) in the second region.

12. The reactor (200) according to claim 11, designed as a reactor for steam reforming, dry reforming, or catalytic dehydrogenation of alkanes.

13. The reactor (100, 200) according to any one of claims 1 to 12, wherein the rigid joint element (30) and the tube portions (21, 22) are formed from the same material or from different materials with conductivity of 50% or less, preferably 30% or less, particularly preferably 10% or less, in particular from chromium-nickel steel containing 0.1 to 0.5 wt% carbon, 20 to 50 wt% chromium, 20 to 80 wt% nickel, 0 to 2 wt% niobium, 0 to 3 wt% silicon, 0 to 5 wt% tungsten, and 0 to 1 wt% other components, preferably 20 to 40 wt% chromium, 20 to 50 wt% nickel, 0 to 10 wt% silicon, 0 to 10 wt% aluminum, and 0 to 4 wt% niobium, in any case the content of the specified components complements each other to form a non-ferrous fraction.

14. The reactor (100, 200) according to any one of claims 1 to 13, wherein the rigid bonding element (30) is at least partially surrounded by a conductive element (31) made of or formed from a material rich in molybdenum, tungsten, tantalum, niobium, and / or chromium, and / or the conductive element (31) has a higher specific conductivity than the material on which the rigid bonding element is formed.

15. A method for carrying out a chemical reaction using a reactor (100, 200) having a reactor vessel (10) and at least one reaction tube (20), wherein multiple tube sections (21, 22) of the at least one reaction tube (20) pass between a first region (11) and a second region (12) in the reactor vessel (10), and for heating of the tube sections (21, 22), the tube sections (21, 22) in the first region (11) are electrically connected to the phase junction of a multiphase AC power supply (50), and the method is used by the reactor (100, 200) to generate heat A method characterized in that, for generating, the tube portions (21, 22) are used as electrical resistors, the tube portions (21, 22) in the second region (12) are electrically connected by at least one rigid bonding element (30), the at least one rigid bonding element (30) is integrally connected to the at least one reaction tube (20) and is arranged in the reactor vessel (10) as one or more star bridges to achieve equipotentiality, and the at least one rigid bonding element (30) is operated at a temperature higher than 700°C.

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