Energy Recovery

Abstract

The invention proposes an apparatus (110) comprising a number of tubes, at least one of which is configured as a reactor tube (112) for the flow of at least one feedstock. The apparatus (110) comprises at least one energy recovery shell (130) at least partially surrounding the reactor tube (112). The energy recovery shell (130) comprises at least one thermoelectric generator configured to convert heat into electrical energy.

Description

[Technical field]

[0001] The present invention relates to an apparatus, a plant and a method for recovering electrical energy comprising a multitude of hollow cylindrical tubes.

[0002] The apparatus may be part of a plant, for example a plant for carrying out at least one endothermic reaction, a plant for heating, a plant for preheating, a steam cracker, a steam reformer, an apparatus for alkane dehydrogenation, a reformer, an apparatus for dry reforming, an apparatus for styrene production, an apparatus for ethylbenzene dehydrogenation, a cracker, a catalytic cracker, an apparatus for the production and dehydrogenation of acetylene. The apparatus may in particular be used for heating the feedstock to a temperature in the range from 200° C. to 1700° C., preferably from 300° C. to 1400° C., more preferably from 400° C. to 875° C. However, other fields of use are also conceivable. [Background technology]

[0003] Production plants such as steam crackers are basically known to the person skilled in the art, see for example Ethylene, Heinz Zimmermann, Roland Walzl, Ullmann's Encyclopedia of Industrial Chemistry (April 15, 2009). In a steam cracker, for example, crude gasoline (naphtha) is split into ethylene and propylene at high temperatures in the presence of steam. In the so-called convection zone of the steam cracker, the crude gasoline is preheated for this purpose and hot steam is added. In the downstream radiant zone, at about 850 ° C, the crude gasoline is split into ethylene and propylene, i.e. cracked. Steam crackers are conventionally heated by the combustion of natural gas, which is associated with carbon emissions. In conventional steam crackers, the heat generated in the combustion of natural gas is not only used for cracking, but also the waste heat rising in the chimney is used to preheat the crude gasoline in the convection zone. Such conventional production plants are known, for example, from EP 2 653 524, US Pat. No. 4,361,478, EP 0 245 839 or EP 3 415 587.

[0004] Electrically heatable reactors are also known, for example from WO 2015 / 197181, WO 2020 / 035575 and WO 2020 / 035574, the contents of which are incorporated herein by reference. Electrically heatable reactors can enable CO2-neutral operation of the reactor. Heat integration of electrically heatable reactors is known from international application PCT / EP2021 / 077144, filed October 1, 2021, the contents of which are incorporated herein by reference.

[0005] US Patent No. 3 881 962 describes a thermoelectric type generator that separates the fuel combustion area from several thermoelectric elements or modules and uses two-phase steam heat transfer, in which the transfer from liquid to gaseous phase takes place through the intervening presence of a boiler that houses a fuel burner. The fuel consumed in the boiler produces heat, which fits into the shell of the boiler that surrounds the vaporizable fluid. The heating steam thus produced flows through a number of heat exchange loops emanating from the boiler in order to heat the hot connection points of the thermoelectric elements. Electrical energy is produced by an electrical potential that is generated between the hot and cold connection points of the aforementioned elements.

[0006] Japanese Patent Application Laid-Open No. 06-154589 describes an insulated container equipped with a device for heating or cooling the container body, a device for supplying a heat exchange fluid into the container to control the temperature inside the container and guide heat exchange between the heat exchange fluid and the atmosphere of the container, a thermoelectric device for converting thermal energy obtained by heat exchange into electrical energy using the heat exchange fluid diverted outside the container after the heat exchange, and a device for storing electrical energy generated by the device. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] European Patent No. 2653524 [Patent Document 2] U.S. Pat. No. 4,361,478 [Patent Document 3] European Patent No. 0245839 [Patent Document 4] European Patent No. 3415587 [Patent Document 5] International Publication No. 2015 / 197181 Brochure [Patent Document 6] International Publication No. 2020 / 035575 Brochure [Patent Document 7] International Publication No. 2020 / 035574 Brochure [Patent Document 8] International Application No. PCT / EP2021 / 077144 [Patent Document 9] U.S. Pat. No. 3,881,962 [Patent Document 10] Japanese Patent Application Publication No. 06-154589 [Non-patent literature]

[0008] [Non-Patent Document 1] Ethylene, Heinz Zimmermann, Roland Walzl, Ullmann's Encyclopedia of Industrial Chemistry (April 15, 2009) Summary of the Invention [Problem to be solved by the invention]

[0009] Conventional electrically heatable reactors require energy to operate, and energy recovery is a continuing problem. [Means for solving the problem]

[0010] It is therefore an object of the present invention to provide an apparatus, a plant and a method for the recovery of electrical energy, which at least to a large extent avoids the disadvantages of known apparatus and methods. In particular, the recovery of energy should be made possible.

[0011] This object is achieved by an apparatus, a plant and a method having the features of the independent claims. Preferred configurations of the invention are specified inter alia in the associated dependent claims and in the dependent references to the dependent claims.

[0012] The expressions "having", "comprises" or "including" or any grammatical variants thereof are used in the following non-exclusively. These expressions may therefore relate either to the situation in which there are no further features apart from the features introduced by these expressions, or to the situation in which one or more further features are present. For example, the expressions "A has B", "A comprises B" or "A includes B" may relate both to the situation in which there are no further elements in A apart from B (i.e., as opposed to the situation in which A consists only of B) and to the situation in which, in addition to B, A has one or more further elements, such as element C, elements C and D, or even further elements.

[0013] It is also pointed out that the expressions "at least one" and "one or more" as well as grammatical variations of these expressions or similar expressions, when they are used in connection with one or more elements or features and are intended to indicate that the element or feature may be provided one or more times, are generally only used once, e.g., when the feature or element is first introduced. When the feature or element is mentioned again at a later time, the corresponding expressions "at least one" or "one or more" are generally no longer used, without limiting the possibility that the feature or element may be provided one or more times.

[0014] Furthermore, the expressions "preferably", "particularly", "for example" or similar expressions are used below together with optional features, without thereby limiting alternative embodiments. Features introduced by these expressions are therefore optional features, and are not intended to limit the scope of protection of the claims, in particular the independent claims. As a person skilled in the art will understand, the invention may also be implemented using other configurations. Similarly, features introduced by "in one embodiment of the invention" or "in one example of the invention" are to be understood as optional features, and are not intended to limit alternative configurations or the scope of protection of the independent claims. Furthermore, all possible combinations of features introduced thereby together with other features, whether optional or non-optional, remain unaffected by these introduction expressions.

[0015] In a first aspect of the invention, an apparatus is proposed that comprises a number of tubes, at least one of which is configured as a reaction tube for at least one feedstock to flow through. The apparatus comprises at least one energy recovery shell at least partially surrounding the reaction tube. The energy recovery shell comprises at least one thermoelectric generator configured to convert heat into electrical energy.

[0016] The apparatus may be usable and the method described below may be employable in a plant selected from the group consisting of a plant for carrying out at least one endothermic reaction, a plant for heating, a plant for preheating, a steam cracker, a steam reformer, an apparatus for alkane dehydrogenation, a reformer, an apparatus for dry reforming, an apparatus for styrene production, an apparatus for ethylbenzene dehydrogenation, an apparatus for the production of acetylene, a cracker, a catalytic cracker, an apparatus for dehydrogenation.

[0017] The expression "tube" as used herein is a broad expression to be ascribed its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer in particular to a hollow body of any shape, without limitation. The length of the tube may be greater than its diameter. The tube may have an interior separated from the external environment by a shell surface. The tube may be configured as a tube through which a flow can pass, also called a flow tube. The tube may comprise at least one pipeline and / or at least one pipeline segment and / or at least one pipeline coil. A pipeline segment may be a sub-region of a pipeline. The expressions "tube", "pipeline" and "pipeline segment" and "pipeline coil" are used below as synonyms.

[0018] For example, the tube may be a hollow cylindrical tube. The expression "hollow cylindrical tube" as used herein is a broad expression to be ascribed its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, in particular to a tube having at least a partially cylindrical portion. The tube may be of a completely cylindrical configuration and may further have a non-cylindrical portion. The hollow cylindrical tube may be, for example, a circular cylinder with a radius r and a length h, also referred to as the height. The circular cylinder may have a bore along the axis. Deviations from the cylindrical shape are also conceivable. For example, the tube may have an elliptical cross-sectional area. For example, the tube may have a prismatic shape. For example, at least one of the tubes of the device may have a rectangular shape.

[0019] The apparatus comprises a number of tubes. The reaction tube may be surrounded by further tubes. The tubes may be in a concentric arrangement. The reaction tube may be arranged as a central tube surrounded by further tubes. The apparatus may have a multi-part configuration, for example with an M-shaped, U-shaped or W-shaped coil as the reaction tube and a straight section of the same length with further tubes attached.

[0020] The expression "feedstock" as used herein is a broad expression to be ascribed its ordinary and common meaning as understood by those skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer in particular to essentially any free-flowing medium, without limitation. The feedstock may be liquid or gaseous. The feedstock may include at least one medium selected from the group consisting of air, at least one oxygen-containing medium, water, water vapor, and at least one oxidizing medium. Other feedstocks are also contemplated.

[0021] In order to carry out at least one endothermic reaction, several side reactions take place in the above-mentioned plants, which can lead, for example, to coking of the plant components, in particular the reaction tubes. It is therefore customary, for example, to carry out exothermic reactions at fixed or regular intervals in order to burn off the coking, in particular the so-called decoking of the plant. In the case of decoking, a feedstock, also called decoking gas, can be fed to the reaction tubes, and the coking can be burned off from the at least one exothermic reaction.

[0022] The expression "flowing through" used herein is a broad expression that should be ascribed its ordinary and common meaning as understood by those skilled in the art. The expression is not limited to a specific or suitable meaning. In particular, the expression may relate to, but is not limited to, one or more of the following: accommodation of the feedstock in the reactor tube, flow of the feedstock through the reactor tube, conduction of the feedstock, for example, transport of the feedstock from a first end of the reactor tube to a second end of the reactor tube.

[0023] The expression "reaction tube" as used herein is a broad expression to be ascribed its ordinary and general meaning as understood by those skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, in particular to a tube configured to allow a feedstock to flow therethrough. The reaction tube may be configured to allow at least one chemical reaction and / or side reaction to proceed in the reaction tube. In particular, the reaction tube may be configured to allow at least one feedstock to flow therethrough to perform at least one endothermic reaction. For example, at least one endothermic reaction may be performed in the reaction tube. For example, an exothermic reaction for decoking and / or oxidation of deposits formed in the endothermic reaction may be performed in the reaction tube.

[0024] The reaction tube may be configured, for example, to heat the feedstock. The reaction tube may be a reactor and / or a furnace or part thereof. For example, the reaction tube may be configured as a reactor of a fired furnace and / or an electrically heatable reactor. For example, the reaction tube may be configured as a reactor of a fired furnace, as described, for example, in H. Zimmermann and R. Walzl, "Ethylene", Ullmann's Encyclopedia of Industrial Chemistry, 2012 Wiley-VCH Verlag GmbH&Co.KGaA, Weinheim, DOI:10.1002 / 14356007.a10_045.pub3, EP 2 653 524, US Pat. No. 4,361,478, EP 0 245 839 or EP 3 415 587. For example, the reaction tube may be configured as an electrically heatable reactor, for example as described in WO 2015 / 197181, WO 2020 / 035575 and WO 2020 / 035574.

[0025] The shape and / or surface and / or material of the reaction tube may depend on the feedstock. Alternatively or additionally, the shape and / or surface and / or material of the reaction tube may depend on the desired reaction and / or the avoidance of certain reactions and / or the optimization of reactions and / or other factors. For example, the reaction tube may be configured as a hollow cylinder.

[0026] The apparatus may comprise a number of reaction tubes. The apparatus may have l reaction tubes, l being a natural number equal to or greater than 2. For example, the apparatus may comprise at least 2, 3, 4, 5 or more reaction tubes. The apparatus may have, for example, up to 100 reaction tubes. The reaction tubes may be of the same or different configurations. The reaction tubes may be of different configurations, for example, with respect to diameter and / or length and / or shape. The reaction tubes may include symmetric and / or asymmetric pipes and / or combinations thereof. In a purely symmetric configuration, the apparatus may comprise reaction tubes of the same tube type. "Asymmetric pipe" and "combination of symmetric and asymmetric pipes" may be taken to mean that the apparatus may comprise any combination of tube types, for example, additionally connected in parallel or series as required. The expression "tube type" as used herein is a broad expression to be ascribed to its ordinary general meaning as understood by a person skilled in the art. This expression is not limited to a specific or adapted meaning. This expression may relate, without limitation, more specifically to a category or type of tube characterized by a particular feature. The tube type may be characterized by at least one feature selected from the group consisting of horizontal configuration of the tubes, vertical configuration of the tubes, length of the inlet (l1) and / or outlet (l2) and / or transition (l3), diameter of the inlet (d1) and outlet (d2) and / or transition (d3), number of passes n, length per pass, diameter per pass, shape, surface and material. The device may include a combination of at least two different tube types connected in parallel and / or in series. For example, the device may comprise tubes with different lengths at the inlet (l1) and / or outlet (l2) and / or transition (l3). For example, the device may comprise tubes with asymmetric diameters at the inlet (d1) and / or outlet (d2) and / or transition (d3). For example, the device may comprise tubes with different numbers of passes. For example, the device may comprise tubes with passes with different lengths per pass and / or different diameters per pass. In principle, any combination of any tubes in parallel and / or in series is conceivable. The apparatus may have multiple inlets and / or outlets and / or production streams.Reactor tubes of different or same tube types may be arranged in parallel and / or in series with multiple inlets and / or outlets. Possible tubes for the reaction tubes may take the form of various tube types in the form of a building kit, which may be selected and combined as needed depending on the end use. The use of tubes of different tube types may allow for more precise temperature control and / or regulation of the reaction when the feed is fluctuating, and / or selective yield of the reaction and / or optimized methodology. The tubes may have the same or different shapes and / or surfaces and / or materials.

[0027] The reaction tubes may be connected through and thus form a tube system. The expression "tube system" as used herein is a broad expression to be ascribed its ordinary general meaning as understood by the skilled person. The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, to an apparatus composed of at least two tubes in particular connected to each other. The tube system may comprise an inlet tube and an outlet tube. The tube system may comprise at least one inlet for receiving the feedstock. The tube system may comprise at least one outlet for discharging the feedstock. "Through-connection" may be understood to mean that the tubes are interconnected in a fluid-conducting manner. The tubes may thus be arranged and connected such that the feedstock flows through the tubes one after the other. Two or more or all of the tubes may be configured in series and / or in parallel. The tubes may be interconnected in parallel with each other such that the feedstock can flow through at least two tubes in parallel. The tubes, in particular the parallel-connected tubes, may be designed to transport different feedstocks in parallel. In particular, the parallel connected pipes may have different shapes and / or surfaces and / or materials for transporting different feedstocks. In particular, for transporting a feedstock, some or all of the pipes may be in a parallel configuration so that the feedstock can be divided between the pipes in the parallel configuration. A combination of series and parallel connections is also conceivable.

[0028] The reaction tube may be an electrically conductive, in particular metallic, or a non-conductive reaction tube.

[0029] For example, the reaction tube may be an electrically conductive reaction tube. The term "electrically conductive" as used herein is a broad term that should be ascribed its ordinary and general meaning as understood by those skilled in the art. The term is not limited to a specific or applicable meaning. The term may refer, without limitation, to a material of the reaction tube that is specifically configured to conduct electric current. The reaction tube may be a 10 -1 The reactor tube may have a specific electrical resistivity of less than 1·10 -8 Ωm≦ρ≦10 -1 The reactor tube may have a specific electrical resistivity ρ of Ωm. The specific electrical resistivity in the context of the present invention relates to the specific electrical resistivity at room temperature. For example, the reactor tube may comprise at least one material selected from the group consisting of at least one ferritic material, at least one austenitic material, at least one metal, at least one metal alloy, copper, aluminum, iron, steel alloy, Cr alloy and / or Ni alloy, graphite, carbon, carbide, silicide.

[0030] The reactor tubes and the corresponding inflow and outflow pipelines may be fluidly connected to each other. When using conductive tubes as reactor tubes, the inflow and outflow pipelines may be galvanically insulated from each other. "Galvanically insulated from each other" may be taken to mean that the pipelines and the inflow and outflow pipelines are insulated from each other such that there is no electrical conduction and / or permissible electrical conduction between the pipelines and the inflow and outflow pipelines. The apparatus may comprise at least one insulator, in particular multiple insulators. Galvanic isolation between the respective pipelines and the inflow and outflow pipelines may be ensured by the insulators. The insulators may ensure the free flow of the feedstock.

[0031] However, configuration of the reactor tube as a non-conductive or poorly conductive tube is also contemplated, for example, the reactor tube may be made of ceramic or a material having a similar resistivity. The reactor tube may be configured as a galvanic insulator. 5 The reactor tube may have a specific electrical resistivity of more than 1x10 5 Ωm≦ρ≦1x10 20 Ωm, preferably 1x10 5 Ωm≦ρ≦1x10 14 The reactor tube may have a specific electrical resistivity ρ of Ωm. For example, the reactor tube may be configured as a ceramic tube. For example, the reactor tube may include at least one material selected from the group consisting of MgO, Al2O3, boron nitride, aluminum nitride, aluminum silicate (mullite), ZrO2, magnesium aluminum silicate (cordierite), magnesium silicate (steatite), and silicon nitride.

[0032] The expression "shell" as used herein is a broad expression to be ascribed its ordinary and common meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer in particular, without limitation, to an element or elements that form a complete or partial boundary in two dimensions between an inner region and an outer region. The shell may be a casing. The shell may be constituted by one or more of a tube, a thin film, a coating or a layer that at least partially surrounds and / or encases further elements of the device. The expressions "surround" and "enclose" are used here as synonyms. The shell may perform various functions, such as, for example, heating, cooling, conducting current, galvanic insulation, etc.

[0033] For example, the device may comprise at least one heating shell. The device may have at least one power source or voltage source configured to generate an electric current in the heating shell, which heats the reaction tube by Joule heat generated upon passage of the electric current through the heating shell. The expression "heating shell" as used herein is a broad expression to be ascribed to its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, in particular to a shell configured to transfer energy supplied thereto in the form of heat to the reaction tube. The heating shell may at least partially surround the reaction tube. The shape and / or material of the heating shell may be adapted to the reaction tube to be heated. For example, energy-efficient heating of the reaction tube may be possible.

[0034] The heating shell may comprise at least one material selected from the group consisting of ferritic and austenitic materials, such as CrNi alloys, CrMo or ceramics. For example, the heating shell may be made of at least one metal and / or at least one alloy, such as copper, aluminum, iron, steel or Cr or Ni alloys, graphite, carbon, carbides, silicides. Semiconductors, such as Ge, Si, selenides, tellurides, arsenides, antimonides, are also considered as materials for the heating shell.

[0035] The heating shell may be an electric current heating shell. The expression "electric current heating shell" as used herein is a broad expression to be ascribed its ordinary and common meaning as understood by a person skilled in the art. This expression is not limited to the suitability of the heating shell, particularly at least one material of the heating shell configured to conduct electric current. The heating shell may be, in particular, accompanied by a connected power source or voltage source, and may be 1x10 -8 Ωm≦ρ≦10 5The heating shell may have a specific electrical resistivity ρ of Ωm. The heating shell may have a thermal conductivity λ of 10 W / (mK)≦λ≦6000 W / (mK), preferably 20 W / (mK)≦λ≦5000 W / (mK). Thermal conductivity in the context of the present invention relates to thermal conductivity at room temperature. The heating shell may be thermally stable within a range of up to 2000° C., preferably up to 1300° C., more preferably up to 1000° C. The expression "thermally stable" used here is a broad expression that should be ascribed to its ordinary general meaning as understood by a person skilled in the art. This expression is not limited to a specific or adapted meaning. This expression may relate, without limitation, to the resistance of the heating shell, in particular the material of the heating shell, to high temperatures in particular.

[0036] As described above, the apparatus may have at least one power source or at least one voltage source configured to generate an electric current in the heating shell that heats the reaction tube by Joule heat generated upon passage of the electric current through the heating shell. The power source and / or voltage source may include a single-phase or multi-phase AC power source and / or a single-phase or multi-phase AC voltage source or a DC power source and / or a DC voltage source. The apparatus may have at least one input and output that electrically connects the power source and / or voltage source to the heating shell.

[0037] The device may, for example, have at least one AC power source and / or at least one AC voltage source. The AC power source and / or AC voltage source may be a single-phase or multi-phase source. The expression "AC power source" as used herein is a broad expression to be ascribed to its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, to a power source configured in particular to provide an AC current. The expression "AC current" as used herein is a broad expression to be ascribed to its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, to a current of polarity that changes in a regular repetition. For example, the alternating current may be a sinusoidal alternating current. The expression "single-phase" as used herein is a broad expression to be ascribed to its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, to an AC power source that provides in particular a single-phase current. The expression "multi ... The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, to an AC power source that supplies a current with two or more phases. The expression "AC voltage source" as used herein is a broad expression that should be ascribed its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, to a voltage source that is configured to supply an AC voltage. The expression "AC voltage" as used herein is a broad expression that should be ascribed its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, to a voltage that has a level and polarity that change in a regular repetition. For example, the AC voltage may be a sinusoidal AC voltage. The voltage generated by an AC voltage source causes a current to flow, in particular an alternating current. A "single-phase" AC voltage source may be taken to mean an AC voltage source that supplies an alternating current with a single phase.A "polyphase" AC voltage source may be taken to mean an AC voltage source that supplies alternating current with two or more phases.

[0038] The device may have at least one DC power source and / or at least one DC voltage source. The expression "DC power source" as used herein is a broad expression to be ascribed to its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, to a device that is specifically configured to provide a DC current. The expression "DC voltage source" as used herein is a broad expression to be ascribed to its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, to a device that is specifically configured to provide a DC voltage. The DC power source and / or the DC voltage source may be configured to generate a DC current in the heating shell. The expression "DC current" as used herein is a broad expression to be ascribed to its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, to a current that is essentially constant in expression of intensity and direction. The expression "DC voltage" as used herein is a broad expression to be ascribed to its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. This expression may refer in particular, without limitation, to an essentially constant voltage. "Essentially constant" may be taken to mean a current or voltage having variations that are insignificant with respect to the intended effect.

[0039] The apparatus may have multiple heating zones. For example, the apparatus may have two or more heating zones. Each heating zone may comprise at least one heating shell. The apparatus may also have regions where there is no heating of the feedstock, for example a simple transport zone.

[0040] The apparatus may have multiple power sources and / or voltage sources, said power sources and / or voltage sources being selected from the group consisting of single-phase or multi-phase AC power sources and / or single-phase or multi-phase AC voltage sources or DC power sources and / or DC voltage sources, and combinations thereof. The apparatus may have 2 to M different power sources and / or voltage sources, M being a natural number equal to or greater than 3. The power sources and / or voltage sources may be configured with or without the possibility to control at least one electrical output variable. The power sources and / or voltage sources may be electrically controllable independently of each other. The power sources and / or voltage sources may be of the same or different configuration. For example, the apparatus may be configured such that the current and / or voltage are adjustable for different zones, in particular heating zones of the apparatus, in particular heating shells. The apparatus may have multiple reaction tubes. The reaction tubes may share a common heating shell or each may have an assigned heating shell. The reaction tubes may belong to different temperature regions or zones. The reaction tubes themselves may have temperature zones as well. An individual reaction tube may be assigned one or more power sources or voltage sources. The power and / or voltage supply can be adjusted, for example, by using at least one controller, depending on the reaction and methodology in each case. The use of multiple power and / or voltage sources makes it possible to vary the voltage, especially for different zones. For example, it is possible to achieve not too high a current, which would result in an excessively hot reaction tube, or conversely an excessively cold reaction tube.

[0041] The device may have multiple single-phase or multi-phase AC power sources or AC voltage sources. Each reaction tube may be assigned at least one heating shell with at least one AC power source and / or AC voltage source electrically connected to the heating shell, in particular via at least one electrical connection. An embodiment is also conceivable in which at least two reaction tubes share the heating shell and the AC power source and / or AC voltage source. To connect the AC power sources or AC voltage sources and the heating shells, the device may have 2 to N inputs and outputs, N being a natural number greater than or equal to 3. Each AC power source and / or AC voltage source may be set to generate an electric current in the respective heating shell. The AC power sources and / or AC voltage sources may be controlled or uncontrolled. The AC power sources and / or AC voltage sources may be configured with or without the possibility of controlling at least one electrical output variable. The expression "output variable" as used herein is a broad expression that should be ascribed to its ordinary and general meaning as understood by a person skilled in the art. This expression is not limited to a specific or adapted meaning. This expression may relate, in particular, to current values ​​and / or voltage values ​​and / or current signals and / or voltage signals, without limitation. The apparatus may have from 2 to M different AC power sources and / or AC voltage sources, where M is a natural number equal to or greater than 3. The AC power sources and / or AC voltage sources may be independently electrically controllable. For example, different currents may be generated in each heating shell to reach different temperatures in the reaction tubes.

[0042] The apparatus may comprise multiple DC power sources and / or DC voltage sources. Each reaction tube may be assigned at least one heating shell and at least one DC power source and / or DC voltage source electrically connected to the heating shell, in particular via at least one electrical connection. An embodiment is also conceivable in which at least two reaction tubes share the heating shell and the DC power source and / or DC voltage source. For the connection of the DC power source and / or DC voltage source with the heating cylinder, the apparatus may have 2 to N positive terminals and / or conductors and 2 to N negative terminals and / or conductors, where N is a natural number equal to or greater than 3. Each DC power source and / or DC voltage source may be configured to generate an electric current in the respective heating shell. The generated electric current may heat the respective reaction tube by Joule heating, which occurs when the electric current passes through the heating shell, in order to heat the feedstock.

[0043] The electric current generated in the heating shell can heat each reaction tube by Joule heat generated when the electric current passes through the heating shell in order to heat the feedstock. The expression "heating the reaction tube" as used herein is a broad expression to be ascribed its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer, without being limited, in particular to an operation that results in a change in the temperature of the reaction tube, in particular an increase in the temperature of the reaction tube, and / or has the effect that the temperature of the reaction tube remains essentially constant, for example when the reaction taking place in the reaction tube consumes the same amount of heat as it receives. The expressions "heating" and "warming" are used synonymously. The feedstock may be heated, for example, to a defined or predetermined temperature value. The device may be set to heat the feedstock to a temperature in the range of 200°C to 1700°C, preferably 300°C to 1400°C, more preferably 400°C to 875°C. However, other temperatures and temperature ranges are also conceivable.

[0044] The reaction tube may be configured to at least partially absorb Joule heat generated by the heating shell and at least partially release it to the feedstock. For example, at least one endothermic reaction may be carried out in the reaction tube. The expression "endothermic reaction" as used herein is a broad expression to be ascribed to its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, in particular to a reaction in which energy, in particular energy in the form of heat, is consumed from the environment. The endothermic reaction may include heating and / or preheating of the feedstock. In particular, the feedstock may be heated in the reaction tube.

[0045] The device may have at least one temperature sensor configured to determine, in particular to measure, the temperature of the reaction tube. The temperature sensor may comprise an electric or electronic element configured to generate an electric signal as a function of temperature. For example, the temperature sensor may have at least one element selected from the group consisting of hot conductors, cold conductors, semiconductor temperature sensors, temperature sensors with vibrating crystals, thermocouples, pyroelectric materials, pyrometers, thermal imaging cameras, ferromagnetic temperature sensors, fiber optic temperature sensors. The temperature may be measured at the inlet and outlet of the reaction tube in and / or on the reaction tube. For example, it is possible to perform measurements at several points in the reaction tube in order to determine the temperature over the length of the reaction tube and to adapt it to the optimal process regime. The closed-loop control on the temperature may be performed by at least one closed-loop control element. This may for example be to switch off the power or voltage supply in case of a hot spot. When the temperature is too low, the closed-loop control may increase the power or voltage supply. The temperature sensor may be connected to a closed-loop controller by a remote or fixed connection. The closed-loop controller may be connected to a power or voltage source by a remote or fixed connection. Temperature measurement and closed-loop control may be possible in so-called "closed-loop mode" by means of an installed temperature sensor and closed-loop current and / or voltage control.

[0046] The device may have at least one control unit configured to control a power supply or voltage source by closed-loop control as a function of the temperature measured by the temperature sensor. The expression "control unit" as used herein is a broad expression to be ascribed its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, in particular to an electronic device configured to control at least one element of the device by open-loop and / or closed-loop control. For example, the control unit may be configured to evaluate the signal generated by the temperature sensor and to control the power supply or voltage source by closed-loop control as a function of the measured temperature. For example, one or more electronic connections may be provided between the temperature sensor and the control unit for this purpose. The control unit may for example comprise at least one data processing device, for example at least one computer or microcontroller. The data processing device may have one or more volatile and / or non-volatile memory elements, in which case the data processing device may for example be programmed to operate the temperature sensor. The control unit may also comprise at least one interface, for example an electronic interface and / or a human-machine interface, for example an input / output device such as a display and / or a keyboard. The control unit may be constructed, for example, in a centralized or distributed manner. Other configurations are also conceivable. The control unit may include at least one A / D converter. The device may include an online temperature measurement. "Online temperature measurement" in the context of the present invention may be understood to mean a measurement of temperature by at least one temperature sensor, which is performed during the transport of the feedstock and / or the reaction in the reaction tube. For example, a closed-loop control of the temperature during operation is possible. In particular, the temperature measurement and the closed-loop control may be performed over the length of the reactor.

[0047] The heating shell may be arranged such that the heating shell at least partially surrounds the reaction tube. "At least partially surround" may be taken to mean embodiments in which one element completely surrounds another element, and in which an element surrounds only a sub-region of the other element. For example, this may include embodiments in which the heating shell completely surrounds the reaction tube, and in which only a sub-region of the reaction tube is surrounded by the heating shell. For example, the reaction tube may be arranged as an inner cylinder of the heating shell. For example, multiple reaction tubes may be arranged in the heating shell. For example, two or more heating shells may be arranged in the form of a ring around the reaction tube. For example, the reaction tube may be helical in shape and the heating shell may be arranged around the reaction tube. Also contemplated are embodiments in which different or identical heating shells are arranged around different regions of the reaction tube or two or more reaction tubes, allowing for separate heating of regions of the reaction tube.

[0048] The heating shell may be configured to directly surround the reaction tube and to release its heat generated by the electric current to the reaction tube. The expression "directly surround" as used herein is a broad expression to be ascribed its normal general meaning as understood by the person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may in particular, without limitation, relate to the arrangement of the reaction tube and the heating shell as adjacent tubes of the apparatus. In particular, no further tube may be arranged between the reaction tube and the heating shell. The reaction tube may for example be a non-conductive, in particular a non-metallic, reaction tube. The reaction tube may be configured as a directly electrically heated reaction tube. The reaction tube and the heating shell may be configured as a monolithic tube, in particular a single conductive tube, which is heated by Joule heating via the passage of an electric current. The reaction tube and the heating shell may be made in one piece.

[0049] However, other arrangements of the reaction tube and the heating shell are also conceivable. For example, the heating shell can indirectly surround the reaction tube. The expression "indirectly surround" as used herein is a broad expression to be ascribed its ordinary general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may in particular, without limitation, relate to an arrangement of a reaction tube and a heating shell in which at least one further element of the apparatus, in particular a further tube, is arranged between the reaction tube and the heating shell. The reaction tube may for example be an electrically conductive, in particular a metallic, reaction tube. The apparatus may comprise at least one galvanic insulator, in particular a thermally conductive one. The galvanic insulator may be arranged between the reaction tube and the heating shell. The galvanic insulator may be configured to galvanically insulate the reaction tube from the heating shell and to transfer heat from the heating shell to the reaction tube. The expression "galvanic insulator" as used herein is a broad expression to be ascribed its ordinary general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The term may refer specifically, without limitation, to non-conductive or poor conductors. Galvanic insulators are 1x10 5 Ωm≦ρ≦1x10 14The galvanic insulator may have a specific electrical resistivity ρ of Ωm. The heat transfer rate may be high. The galvanic insulator may have a thermal conductivity λ of 10 W / (mK)≦λ≦6000 W / (mK), preferably 20 W / (mK)≦λ≦5000 W / (mK). The galvanic insulator may include at least one material selected from the group consisting of ceramic, vitreous, glass-reinforced, plastic-like or resin-like materials, such as ceramic, steatite, porcelain, glass, glass-reinforced plastic, epoxy resin, thermosetting resin, elastomer, and sufficiently electrically insulating liquid, insulating paint. The galvanic insulator may be configured as one or more of a tube, a thin film, a coating, or a layer. The galvanic insulator may be, for example, a flexible galvanic insulator, such as a thin film. In this way, it may allow expansion in the case of a temperature difference. The galvanic insulator may be configured to transfer heat from the energized heating shell to the reaction tube. At the same time, the galvanic insulator can galvanically insulate the reaction tube from the heating shell.

[0050] The apparatus has at least one energy recovery shell that at least partially surrounds the reaction tube. "At least partially surrounding" can be taken to mean embodiments in which one element completely surrounds another element, and in which an element surrounds only a sub-region of the other element. For example, this can include embodiments in which the energy recovery shell completely surrounds the reaction tube, and in which only a sub-region of the reaction tube is surrounded by the energy recovery shell. The expression "energy recovery shell" as used herein is a broad expression that should be ascribed to its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression can relate more specifically, without limitation, to a shell that is configured to at least partially recover the energy consumed for heating the feedstock.

[0051] The energy recovery shell has at least one thermoelectric generator (TEG) configured to convert heat into electrical energy. The term "conversion" as used herein is a broad term to be ascribed its ordinary and general meaning as understood by those skilled in the art. The term is not limited to a specific or adapted meaning. The term may refer in particular to thermoelectric energy conversion, without limitation. Heat may be at least partially converted into energy. For example, the TEG may have an efficiency of 5-10%.

[0052] The expression "thermoelectric generator" as used herein, also called Seebeck generator, is a broad expression to be ascribed its ordinary and general meaning as understood by those skilled in the art. The expression is not limited to a specific or adapted meaning. The term may relate, without limitation, in particular to devices configured to convert heat flow (temperature difference) into electrical energy via what is called the Seebeck effect. The energy recovery shell may be configured to convert heat generated in exothermic reactions in the reactor tubes, in particular in decoking operations, into electrical energy. A chemical reaction may be considered to be exothermic when it releases more energy than was initially provided as activation energy. Exothermic reactions may proceed during decoking and / or oxidation operations on deposits in the reactor tubes. For example, a temperature difference may arise in that, for example after a cooling operation, there is a temperature of 1000°C in the reactor tubes and a temperature of 20°C in the outer shell of the device.

[0053] TEGs may be configured, for example, as described in U.S. Patent Application Publication No. 2014 / 0238459, published by Elsevier Ltd., and Mengjun Zhang et al., "Performance Comparison of Annular and Flat-Plate Thermoelectric Generators for Cylindrical Hot Sauce," https: / / doi.org / 10.1016 / j.egyr.2021.01.008,2352-4847 / 2021. Use of TEGs is known in other technical fields, for example, in thermal power plants in Korean Patent No. 20190040433, in thermoelectric gas cookers for home use in Chinese Patent No. 106953548, in vehicle off-gas systems in European Patent No. 3151293, or in resistive heaters in Japanese Patent Application Publication No. 2008032341 and Japanese Patent Application Publication No. 2002171776.

[0054] The energy recovery shell may include at least one material having a thermoelectric figure of merit ZT of 0.5 or greater, preferably 0.8 or greater, and more preferably 1 or greater. The thermoelectric figure of merit is ZT=(α 2 The thermal conductivity of the energy harvesting shell can be written as (T)·σ(T)·T) / κ(T), where α is the Seebeck coefficient of the material, σ is the electrical conductivity, and κ is the specific thermal conductivity. The energy harvesting shell can be made of lead tellurium (Pb-Te), at least one telluride, at least one silicone, at least one silicate, at least one silicide, at least one Si-Ge silicide, at least one polymer, at least one ceramic, at least one skutterudite, CoSb3 skutterudite, germanium, at least one semi-Heusler alloy, Mg2(Sn,Si), Sr 1-x A x Zinc 1-y Ga y Sn 1-z X z (A: Ca, Ba, La, Eu; X: Si, Sb), Ca 1-x A x Al 2-y TM yThe TEG may comprise at least one material selected from the group consisting of Si2 (A=Sr, Ba; T=Mn, Zn). The TEG may have a thickness of 2 mm to 50 mm, preferably 2 mm to 30 mm, more preferably 5 mm to 30 mm.

[0055] The energy recovery shell may have multiple thermoelectric modules. Thus, the term "module" as used herein is a broad term that should likewise be ascribed its ordinary and general meaning as understood by a person skilled in the art. The term is not limited to a specific or applicable meaning. The term may refer in particular, without limitation, to multi-part embodiments of the energy recovery shell.

[0056] The TEG may be in a flat or annular configuration, for example, as described in Mengjun Zhang et al., "Performance Comparison of Annular and Flat-Plate Thermoelectric Generators for Cylindrical Hot Sources," https: / / doi.org / 10.1016 / j.egyr.2021.01.008,2352-4847 / 2021, published by Elsevier Ltd. The shape and / or modularity of the TEG may depend on the shape of the reaction tube and / or the expected temperature difference.

[0057] The reaction tube and the energy recovery shell may be in a concentric arrangement. The reaction tube may be the inner tube and the energy recovery shell may be further arranged outside. For example, the energy recovery shell may be the outer shell of the device. However, other designs are also conceivable. For example, the device may additionally have an outer shell that at least partially surrounds all the tubes of the device.

[0058] The device may include at least one energy storage means for absorbing electrical energy from the energy recovery shell and / or at least one supply to a consumer for supplying electrical energy from the energy recovery shell. The consumption may be complete or at least partial. The consumption may include storage. The consumption may include conversion of electrical energy into another form of energy. The consumer may be, for example, one or more of a charging station, lighting, another reactor or any other consumer. Examples are a heat exchanger, a heat transferer, an energy storage means, a battery or an accumulator. The absorbed heat may be used to heat the reaction tube from which the energy was recovered or another reaction tube. Other uses of the recovered energy are also conceivable.

[0059] The TEG may be configured so that it can directly extract electrical energy. The device may therefore be configured so that the temperature directly at the TEG is not too high and at the same time not too low. The TEG material used may be stable over a temperature range, in particular at the temperature to which the feedstock is heated. Alternatively or additionally, the device may have further elements for protecting the TEG, for example for cooling or pre-cooling. The temperature may therefore be adjusted depending on the material of the TEG.

[0060] The device may have at least one cooling shell configured to at least partially surround the energy recovery shell. The cooling shell may be configured to cool below room temperature. The expression "cooling shell" as used herein is a broad expression to be ascribed its ordinary and general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may relate, without limitation, in particular to a shell configured to regulate the temperature of the reaction tube, in particular the temperature difference of the reaction tube with respect to the temperature of the shell, for example to a specified value. The cooling shell may have at least one cooling medium.

[0061] The expression "outer shell" used here is a broad expression that should be ascribed its normal general meaning as understood by a person skilled in the art. The expression is not limited to a specific or adapted meaning. The expression may refer, without limitation, in particular to the outermost shell of the device, in particular to the concentric arrangement. The outer shell may house all the elements of the device, in particular all the tubes. The outer shell may be configured as a housing. The outer shell may also be configured to galvanically insulate the device. The outer shell may be thermally insulating and may at least partially reduce the loss of heat to the outside. "At least partially reduce the loss of heat to the outside" in the context of the present invention may be taken to mean embodiments with perfect insulation and even embodiments with incomplete heat reduction, for example heat reduction to a predetermined temperature. For example, the outer shell may surround at least one sub-region along the heating shell, for example at least a particularly heat-sensitive outer region of the environment. With regard to the materials used, the outer shell may be configured with a specific electrical resistivity and thermal conductivity like the galvanic insulator described above between the reaction tube and the heating shell.

[0062] In a further aspect, in the context of the present invention, a plant is proposed which comprises the device of the present invention. With regard to the configuration and definition of the plant, reference may be made further to the description of the device above or below.

[0063] The plant is selected from the group consisting of plants for carrying out at least one endothermic reaction, plants for heating, plants for preheating, steam crackers, steam reformers, units for alkane dehydrogenation, reformers, units for dry reforming, units for styrene production, units for ethylbenzene dehydrogenation, production of acetylene, crackers, catalytic crackers, units for dehydrogenation.

[0064] In a further aspect, in the context of the present invention, a method for recovering electrical energy using the device of the present invention is proposed, said method comprising the following steps: passing the feedstock through a reactor tube; This is the step of converting the heat generated in the reaction tubes during the chemical reaction into electrical energy using a thermoelectric generator in the energy recovery shell.

[0065] The method may further comprise a storage step, in which the electrical energy is stored in at least one energy storage means and / or supplied to a consumer.

[0066] Regarding the embodiments and definitions, reference can be made to the above description of the device. The method steps may be performed in a specified order, but one or more steps may also be performed at least partially simultaneously, and one or more steps may be repeated multiple times. In addition, further steps may be additionally performed, whether or not mentioned in this specification.

[0067] In summary, in the context of the present invention, the following embodiments are particularly preferred:

[0068] Embodiment 1. An apparatus comprising a number of tubes, at least one of the tubes configured as a reaction tube for flowing at least one feedstock, the apparatus having at least one energy recovery shell at least partially surrounding the reaction tube, the energy recovery shell having at least one thermoelectric generator configured to convert heat into electrical energy.

[0069]

[0023] Embodiment 2. The apparatus of the preceding embodiment, wherein the energy recovery shell is configured to convert heat generated in the exothermic reaction in the reaction tubes into electrical energy.

[0070] Embodiment 3. The apparatus of the preceding embodiment, wherein the exothermic reaction proceeds during decoking and / or oxidation of deposits in the reactor tubes.

[0071] Embodiment 4. An apparatus according to any of the preceding embodiments, wherein the energy recovery shell comprises at least one material having a thermoelectric figure of merit ZT of 0.5 or greater, preferably 0.8 or greater, more preferably 1 or greater.

[0072] Embodiment 5 The energy harvesting shell is selected from the group consisting of lead tellurium (Pb-Te), at least one telluride, at least one silicone, at least one silicate, at least one silicide, at least one Si-Ge silicide, at least one polymer, at least one ceramic, at least one skutterudite, CoSb3 skutterudite, germanium, at least one semi-Heusler alloy, Mg2(Sn,Si), Sr 1-x A x Zinc 1-y Ga y Sn 1-z X z (A: Ca, Ba, La, Eu; X: Si, Sb), Ca 1-x A x Al 2-y TM y 13. The apparatus of any preceding embodiment, comprising at least one material selected from the group consisting of: Si2 (A=Sr, Ba; Tm=Mn, Zn).

[0073]

[0023] Embodiment 6. An apparatus according to any of the preceding embodiments, wherein the energy recovery shell comprises a number of thermoelectric modules.

[0074] Embodiment 7. An apparatus according to any of the preceding embodiments, wherein the reaction tube and the energy recovery shell are in a concentric arrangement, the reaction tube being the inner tube and the energy recovery shell being further disposed on the outside.

[0075] Embodiment 8. The device of any of the preceding embodiments, wherein the energy recovery shell is the outer shell of the device.

[0076] Embodiment 9. The device of the preceding embodiment, wherein the device additionally has an outer shell at least partially surrounding all of the tubes of the device.

[0077] Embodiment 10. The apparatus of any of the preceding embodiments, wherein the reaction tube comprises at least one material selected from the group consisting of at least one ferritic material, at least one austenitic material, at least one metal, at least one metal alloy, copper, aluminum, iron, steel alloys, Cr-alloys and / or Ni-alloys, graphite, carbon, carbides, silicides.

[0078] Embodiment 11. The apparatus of any of the preceding embodiments, wherein the reaction tube is a conductive tube.

[0079]

[0031] Embodiment 12. The apparatus of any one of embodiments 1 to 9, wherein the reaction tube is configured as a ceramic tube.

[0080] Embodiment 13. An apparatus according to any of the preceding embodiments, wherein the apparatus has at least one electrically conductive heating shell, the apparatus having at least one current or voltage source configured to generate an electric current in the heating shell, and the heating shell heats the reaction tube by Joule heat generated when an electric current passes through the heating shell.

[0081] Embodiment 14. The apparatus of the preceding embodiment, wherein the heating shell at least partially surrounds the reaction tube.

[0082]

[0023] Embodiment 15. The apparatus of the preceding embodiment, wherein the heating shell immediately surrounds the reaction tube and is configured to emit heat generated by the electric current to the reaction tube.

[0083] Embodiment 16. The apparatus of embodiment 13, wherein the apparatus has at least one galvanic insulator disposed between the reaction tube and the heating shell, the galvanic insulator configured to galvanically insulate the reaction tube from the heating shell and to transfer heat from the heating shell to the reaction tube.

[0084] Embodiment 17. The apparatus according to the preceding embodiment, wherein the galvanic insulator comprises at least one material selected from the group consisting of ceramic, vitreous, fiberglass reinforced, plastic-like or resin-like material, insulating paint, and the galvanic insulator is configured as one or more of a tube, a thin foil, a coating, or a layer.

[0085] Embodiment 18. An apparatus according to any of the five preceding embodiments, wherein the apparatus has at least one temperature sensor configured to determine a temperature of the reaction tube, and the apparatus has at least one control unit configured to control the power source or voltage source by closed-loop control as a function of the temperature measured by the temperature sensor.

[0086] Embodiment 19. An apparatus according to any of the six preceding embodiments, wherein the power source and / or voltage source comprises a single-phase or poly-phase AC power source and / or a single-phase or poly-phase AC voltage source, or a DC power source and / or a DC voltage source.

[0087] Embodiment 20. An apparatus as described in any of the preceding embodiments, wherein the apparatus has at least one cooling shell configured to at least partially surround the energy recovery shell, the cooling shell configured to cool to below room temperature.

[0088] Embodiment 21. An apparatus according to any of the preceding embodiments, wherein the apparatus comprises at least one energy storage means for absorbing electrical energy from the energy recovery shell, and / or at least one supply to a consumer for supplying electrical energy from the energy recovery shell.

[0089] Embodiment 22. An apparatus according to any of the preceding embodiments, wherein the apparatus is configured to heat the feedstock to a temperature in the range of from 200° C. to 1700° C., preferably from 300° C. to 1400° C., more preferably from 400° C. to 875° C.

[0090] Embodiment 23. The apparatus of any of the preceding embodiments, wherein the apparatus has a number of reaction tubes, said apparatus having l reaction tubes, l being a natural number equal to or greater than 2, and said reaction tubes having symmetric or asymmetric pipes and / or combinations thereof.

[0091] Embodiment 24. An apparatus according to any of the preceding embodiments, wherein the feedstock comprises at least one medium selected from the group consisting of air, at least one oxygen-containing medium, water, water vapor, and at least one oxidizing medium.

[0092] Embodiment 25. An apparatus according to any of the preceding embodiments, wherein the reaction tube is configured to receive at least one feedstock for carrying out at least one endothermic reaction.

[0093] Embodiment 26. A plant comprising at least one apparatus according to any of the preceding embodiments, wherein the plant is selected from the group consisting of a plant for carrying out at least one endothermic reaction, a plant for heating, a plant for preheating, a steam cracker, a steam reformer, an apparatus for alkane dehydrogenation, a reformer, an apparatus for dry reforming, an apparatus for styrene production, an apparatus for ethylbenzene dehydrogenation, production of acetylene, a cracker, a catalytic cracker, an apparatus for dehydrogenation.

[0094] Embodiment 27. A method for recovering electrical energy using a device according to any of the preceding device embodiments, said method comprising: passing the feedstock through a reactor tube; converting heat generated in the reaction tube during the chemical reaction into electrical energy using a thermoelectric generator in the energy recovery shell; A method comprising:

[0095] Further details and features of the invention will become apparent from the following description of preferred embodiments, in particular in conjunction with the dependent claims. Each feature may in this case be implemented alone or in combination with two or more of them. The invention is not limited to the embodiments, which are diagrammatically illustrated in the drawings. Identical reference numbers in the individual figures relate to elements which are the same, have the same function or correspond to one another in the expression of their function.

[0096] The individual figures show: [Brief description of the drawings]

[0097] [Figure 1a] FIG. 1 shows an embodiment of an apparatus of the present invention with a reaction tube. [Figure 1b] FIG. 1 shows an embodiment of an apparatus of the present invention with a reaction tube. [Figure 2a] FIG. 1 shows an embodiment of the apparatus of the present invention having multiple reaction tubes. [Figure 2b] FIG. 1 shows an embodiment of the apparatus of the present invention having multiple reaction tubes. [Figure 3a] FIG. 1 shows an embodiment of an apparatus of the present invention with two heating zones. [Figure 3b] FIG. 1 shows an embodiment of an apparatus of the present invention with two heating zones. [Figure 4a] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4b] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4c] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4d] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4e]FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4f] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4g] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4h] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4i] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4j] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4k] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4l] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4m] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4n] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4o] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4p] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4q] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4r] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4s] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4t] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4u] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4v] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4w] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4x] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 4y] FIG. 1 shows examples of embodiments and variants of the device of the invention with a building kit with pipe types for possible reaction tubes. [Figure 5a] FIG. 1 shows an embodiment of the device of the invention with a cooling circuit. [Figure 5b] FIG. 1 shows an embodiment of the device of the invention with a cooling circuit. [Figure 6a] FIG. 1a and FIG. 2a show an embodiment of the device of the invention with a rectangular pipe design. [Figure 6b] FIG. 1a and FIG. 2a show an embodiment of the device of the invention with a rectangular pipe design. [Figure 7a] FIG. 1 shows an embodiment of the device of the present invention with a rectangular pipe design with a cooling circuit. [Figure 7b] FIG. 1 shows an embodiment of the device of the present invention with a rectangular pipe design with a cooling circuit. [Figure 8a] FIG. 1 illustrates an embodiment and use of the device of the present invention with an energy storage unit. [Figure 8b] FIG. 1 illustrates an embodiment and use of the device of the present invention with an energy storage unit. [Figure 8c] FIG. 1 illustrates an embodiment and use of the device of the present invention with an energy storage unit. [Figure 8d] FIG. 1 illustrates an embodiment and use of the device of the present invention with an energy storage unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0098] Working Example 1a and 1b show schematic diagrams of two embodiments of the device 110 of the invention, each with one reaction tube 112. The device 110 comprises a number of tubes. The device 110 comprises, for example, in the embodiment of Figs. 1a and 1b, three hollow cylindrical tubes in a concentric arrangement. At least one of the tubes is configured as a reaction tube 112 for at least one feedstock to flow. The device 110 may have at least one reaction space 111. The device 110 may be usable in a plant selected from the group consisting of plants for carrying out at least one endothermic reaction, plants for heating, plants for preheating, steam crackers, steam reformers, devices for alkane dehydrogenation, reformers, devices for dry reforming, devices for styrene production, devices for ethylbenzene dehydrogenation, production of acetylene, crackers, catalytic crackers, devices for dehydrogenation.

[0099] The reactor tube 112 may be configured as a tube through which material can flow. The reactor tube 112 may be configured to allow feedstock to flow therethrough. The reactor tube 112 may be configured to allow at least one chemical reaction and / or side reaction to proceed in the reactor tube. The reactor tube 112 may comprise at least one pipeline and / or at least one pipeline segment 114 and / or at least one pipeline coil. The pipeline segment 114 may be a sub-region of a pipeline.

[0100] The reaction tubes may be configured to heat the feedstock, for example. The reaction tubes 112 may be reactors and / or furnaces or parts thereof. For example, the reaction tubes 112 may be configured as reactors of fired furnaces and / or electrically heatable reactors. For example, the reaction tubes 112 may be configured as reactors of fired furnaces, as described, for example, in H. Zimmermann and R. Walzl, "Ethylene", Ullmann's Encyclopedia of Industrial Chemistry, 2012 Wiley-VCH Verlag GmbH&Co.KGaA, Weinheim, DOI:10.1002 / 14356007.a10_045.pub3, EP 2 653 524, U.S. Pat. No. 4,361,478, EP 0 245 839 or EP 3 415 587. For example, the reaction tube 112 may be configured as an electrically heatable reactor, for example as described in WO 2015 / 197181, WO 2020 / 035575 and WO 2020 / 035574.

[0101] The shape and / or surface and / or material of the reaction tube 112 may depend on the feedstock. Alternatively or additionally, the shape and / or surface and / or material of the reaction tube 112 may depend on the desired reaction and / or the avoidance of certain reactions and / or the optimization of reactions and / or other factors. For example, the reaction tube 112 may be configured as a hollow cylinder. For example, as shown in Figures 1a to 3b, all tubes of the apparatus 110 may be configured as hollow cylinders. The tubes may be of a completely cylindrical configuration or may even have non-cylindrical parts. The hollow cylinder may be, for example, a circular cylinder with a radius r and a length h, also referred to as the height. The circular cylinder may have a bore along the axis. Deviations from a cylindrical shape are also contemplated. For example, the tubes may have an elliptical cross-sectional area. Other shapes are also contemplated.

[0102] The feedstock can be essentially any free-flowing medium. The feedstock can be liquid or gaseous. The feedstock can comprise at least one medium selected from the group consisting of air, at least one oxygen-containing medium, water, water vapor, and at least one oxidizing medium. Other feedstocks are also conceivable. In order to carry out the at least one endothermic reaction, several side reactions take place in the above-mentioned plant, which can lead, for example, to coking of the plant components, in particular the reaction tubes 112. It is therefore customary, for example, to carry out exothermic reactions at fixed or regular intervals in order to burn off the coking, in particular the so-called decoking of the plant. In the case of decoking, a feedstock, also called decoking gas, can be fed to the reaction tubes 112, and the coking can be burned off from the at least one exothermic reaction.

[0103] The reactor tube 112 may be an electrically conductive, in particular a metallic, reactor tube 112 or a non-conductive reactor tube 112. In the embodiment of FIG. 1a, the reactor tube may be an electrically conductive metal reactor tube. The reactor tube 112 may be -1 The reactor tube 112 may have a specific electrical resistivity of less than 1·10 Ω·m. -8 Ωm≦ρ≦10 -1For example, the reaction tube 112 may comprise at least one material selected from the group consisting of at least one ferritic material, at least one austenitic material, at least one metal, at least one metal alloy, copper, aluminum, iron, steel alloys, Cr-alloys and / or Ni-alloys, graphite, carbon, carbides, and silicides.

[0104] However, configuration of the reactor tube 112 as a non-conductive or poorly conductive tube is also contemplated, as shown in FIG. 1b. For example, the reactor tube 112 may be fabricated from a ceramic or material having a similar resistivity. The reactor tube 112 may be configured as a galvanic insulator. The reactor tubes 112, 10 5 The reactor tube 112 may have a specific electrical resistivity of greater than 1×10 5 Ωm≦ρ≦1x10 20 Ωm, preferably 1x10 5 Ωm≦ρ≦1x10 14 The reactor tube 112 may have a specific electrical resistivity ρ of Ωm. For example, the reactor tube 112 may be configured as a ceramic tube. For example, the reactor tube 112 may include at least one material selected from the group consisting of MgO, Al2O3, boron nitride, aluminum nitride, aluminum silicate (mullite), ZrO2, magnesium aluminum silicate (cordierite), magnesium silicate (steatite), and silicon nitride.

[0105] The apparatus 110 may have at least one heating shell 129, as shown in Figures 1a and 1b. The apparatus 110 may have at least one power source or voltage source 126 configured to generate an electric current in the heating shell 129 that heats the reaction tube 112 by Joule heat generated upon passage of an electric current through the heating shell 129. The heating shell 129 may be any shell configured to transfer energy provided thereto in the form of heat to the reaction tube 112. The heating shell 129 may at least partially surround the reaction tube 112. The shape and / or material of the heating shell 129 may be adapted to the reaction tube 112 to be heated. For example, energy-efficient heating of the reaction tube 112 may be possible.

[0106] The heating shell 129 may comprise at least one material selected from the group consisting of ferritic and austenitic materials, such as CrNi alloys, CrMo or ceramics. For example, the heating shell may be made of at least one metal and / or at least one alloy, such as copper, aluminum, iron, steel or Cr or Ni alloys, graphite, carbon, carbides, silicides. Semiconductors, such as Ge, Si, selenides, tellurides, arsenides, antimonides, are also considered as materials for the heating shell.

[0107] The heating shell 129 may be an electrically conductive heating shell. The heating shell 129 may be, among other things, connected to a power source or voltage source 126, such as a 1x10 -8 Ωm≦ρ≦10 5 The heating shell 129 may have a specific electrical resistivity ρ of Ωm. The heating shell 129 may have a thermal conductivity λ of 10 W / (mK)≦λ≦6000 W / (mK), preferably 20 W / (mK)≦λ≦5000 W / (mK). The heating shell 129 may be thermally stable up to 2000° C., preferably up to 1300° C., more preferably up to 1000° C.

[0108] As mentioned above, the apparatus 110 may have at least one power source or at least one voltage source 126 configured to generate an electric current in the heating shell 129 that heats the reaction tube 112 by Joule heat generated upon passage of an electric current through the heating shell. The power source and / or voltage source 126 may include a single-phase or multi-phase AC power source and / or a single-phase or multi-phase AC voltage source or a DC power source and / or a DC voltage source. The apparatus 110 may have at least one input and output 127 that electrically connects the power source and / or voltage source 126 to the heating shell 129, particularly via electrical terminals 128.

[0109] The electric current generated in the heating shell 129 can heat the reaction tube 112 by Joule heating that occurs when the electric current passes through the heating shell 129 in order to heat the feedstock. The heating of the reaction tube 112 can include at least one operation that results in a change in the temperature of the reaction tube 112, in particular an increase in the temperature of the reaction tube 112, and / or has the effect that the temperature of the reaction tube 112 remains essentially constant, for example when the reaction taking place in the reaction tube 112 consumes the same amount of heat as it receives. The feedstock may be heated, for example, to a defined or predetermined temperature value. The apparatus 110 may be set to heat the feedstock to a temperature in the range of 200° C. to 1700° C., preferably 300° C. to 1400° C., more preferably 400° C. to 875° C. However, other temperatures and temperature ranges are also conceivable.

[0110] The reactor tube 112 may be configured to at least partially absorb Joule heat generated by the heating shell 129 and at least partially release it to the feedstock. For example, at least one endothermic reaction may occur in the reactor tube 112. The endothermic reaction may include heating and / or preheating of the feedstock. In particular, the feedstock may be heated in the reactor tube 112.

[0111] The heating shell 129 may be disposed such that the heating shell 129 at least partially surrounds the reaction tube 112. For example, the heating shell 129 may completely surround the reaction tube 112 or may further surround only a sub-region of the reaction tube 112. For example, the reaction tube 112 may be disposed as an inner cylinder of the heating shell 129. For example, two or more heating shells 129 may be disposed around the reaction tube 112 in the form of a ring. For example, the reaction tube 112 may be in a spiral shape and the heating shell 129 may be disposed around the reaction tube 112. Embodiments are also contemplated in which different or identical heating shells 129 are disposed around different regions of the reaction tube 112 or two or more reaction tubes 112, allowing for separate heating of regions of the reaction tube 112.

[0112] As shown in Fig. 1b, the heating shell 129 may be configured to directly surround the reaction tube 112 and to radiate its heat generated by the electric current to the reaction tube 112. The reaction tube 112 and the heating shell 129 may be arranged as adjacent tubes of the apparatus 110. In particular, no additional tubes may be arranged between the reaction tube 112 and the heating shell 129.

[0113] FIG. 1a shows a different arrangement of the reaction tube 112 and the heating shell 129. In this configuration, the heating shell 129 indirectly surrounds the reaction tube 112. As mentioned above, the reaction tube 112 shown in FIG. 1a may be an electrically conductive, in particular a metallic, reaction tube 112. The apparatus 110 may comprise at least one galvanic insulator 124, in particular a thermally conductive one. The galvanic insulator 124 may be arranged between the reaction tube 112 and the heating shell 129. The galvanic insulator 124 may be configured to galvanically insulate the reaction tube 112 from the heating shell 129 and to transfer heat from the heating shell 129 to the reaction tube 112. The galvanic insulator 124 may be configured to have a thickness of 1×10 5 Ωm≦ρ≦1x10 14 It may have a specific electrical resistivity ρ of Ωm. It may have a high thermal conductivity. The galvanic insulator 124 may have a thermal conductivity λ of 10 W / (mK)≦λ≦6000 W / (mK), preferably 20 W / (mK)≦λ≦5000 W / (mK). The galvanic insulator 124 may include at least one material selected from the group consisting of ceramic, vitreous, glass-reinforced, plastic-like or resin-like materials, such as ceramic, steatite, porcelain, glass, glass-reinforced plastic, epoxy resin, thermosetting resin, elastomer, and sufficiently electrically insulating liquid, insulating paint. The galvanic insulator 124 may be configured as one or more of a tube, a thin film, a coating, or a layer. The galvanic insulator may be, for example, a flexible galvanic insulator, such as a thin film. In this way, it may allow for expansion in the case of a temperature difference. The galvanic insulator 124 can be configured to transfer heat from the energized heating shell 129 to the reactor tube 112. At the same time, the galvanic insulator 124 can galvanically isolate the reactor tube 112 from the heating shell 129.

[0114] 2a and 2b show an embodiment with a number of reaction tubes 112. For the configuration of further elements of the apparatus 110 in FIG. 2a, reference may be made to the description of FIG. 1a, and for the configuration of further elements of the apparatus 110 in FIG. 2b, reference may be made to the description of FIG. 1b. The apparatus 110 may have l reaction tubes 112, where l is a natural number equal to or greater than 2. For example, the apparatus 110 may comprise at least 2, 3, 4, 5 or more reaction tubes 112. The apparatus 110 may comprise, for example, up to 100 reaction tubes 112. For example, the reaction tubes 112 may be disposed within a heating shell 129. For example, the reaction tubes 112 may be helical in shape and the heating shell may be disposed around the reaction tube. Also contemplated are embodiments in which different or identical heating shells may be disposed around different regions of the reaction tube or two or more reaction tubes, allowing for separate heating of regions of the reaction tube.

[0115] The reaction tubes 112 may be connected through and thus form a tube system 118. The tube system 118 may comprise an inlet tube and an outlet tube. The tube system 118 may comprise at least one inlet 120 for receiving the feedstock. The tube system 118 may comprise at least one outlet 122 for discharging the feedstock. The reaction tubes 112 may be fluidly connected to each other. Thus, the reaction tubes 112 may be arranged and connected such that the feedstock flows through the reaction tubes 112 one after the other. Two or more or all of the reaction tubes 112 may be configured in series and / or in parallel. The reaction tubes 112 may be interconnected in parallel with each other such that the feedstock can flow through at least two reaction tubes 112 in parallel. The reaction tubes 112, in particular the tubes connected in parallel, may be designed to transport different feedstocks in parallel. In particular, the tubes connected in parallel may have different shapes and / or surfaces and / or materials from each other for transporting different feedstocks. Some or all of the reactor tubes 112 may be in a parallel configuration, so that the feedstock can be divided between those tubes in a parallel configuration, especially for the transport of one feedstock. A combination of series and parallel connections is also conceivable. When using conductive tubes as the reactor tubes 112, the inflow and outflow pipelines may be galvanically insulated from each other. For this purpose, the device 110 may comprise at least one insulator, in particular multiple insulators. The galvanic isolation between the respective pipelines and the inflow and outflow pipelines may be ensured by the insulators. The insulators may ensure a free flow of the feedstock.

[0116] As shown diagrammatically in FIG. 1a and FIG. 1b, the apparatus 110 has at least one energy recovery shell 130 that at least partially surrounds the reaction tube 112. The energy recovery shell 130 may, for example, completely surround the reaction tube 112. The energy recovery shell 130 may be a shell configured to at least partially recover energy consumed for heating the feedstock. The energy recovery shell 130 has at least one thermoelectric generator (TEG) configured to convert heat into electrical energy. The conversion may be thermoelectric energy conversion. The heat may be at least partially converted into energy. For example, the TEG may have an efficiency of 5-10%.

[0117] The TEG may be a device configured to convert heat flow (temperature difference) into electrical energy via what is called the Seebeck effect. The energy recovery shell 130 may be configured to convert heat generated in exothermic reactions in the reactor tubes, particularly in decoking operations, into electrical energy. A chemical reaction may be considered exothermic when it releases more energy than was initially provided as activation energy. Exothermic reactions may proceed during decoking and / or oxidation operations on the reactor tube deposits. For example, a temperature difference may occur in that the reactor tubes 112 have a temperature of 1000° C. and the outer shell of the apparatus 110 has a temperature of 20° C., for example after a cooling operation.

[0118] The TEG can be configured, for example, as described in U.S. Patent Application Publication No. 2014 / 0238459, published by Elsevier Ltd., “Performance Comparison of Annular and Flat Plate Thermoelectric Generators for Cylindrical Hot Sauce” by Mengjun Zhang et al., https: / / doi.org / 10.1016 / j.egyr.2021.01.008,2352-4847 / 2021.

[0119] The energy recovery shell 130 may include at least one material having a thermoelectric figure of merit ZT of 0.5 or greater, preferably 0.8 or greater, and more preferably 1 or greater. The thermoelectric figure of merit is given by ZT=(α2 The thermal conductivity of the energy harvesting shell 130 may be written as (T)·σ(T)·T) / κ(T), where α is the Seebeck coefficient of the material, σ is the electrical conductivity, and κ is the specific thermal conductivity. The energy harvesting shell 130 may be made of any of the following materials: lead telluride (Pb-Te), at least one telluride, at least one silicone, at least one silicate, at least one silicide, at least one Si-Ge silicide, at least one polymer, at least one ceramic, at least one skutterudite, CoSb3 skutterudite, germanium, at least one semi-Heusler alloy, Mg2(Sn,Si), Sr 1-x A x Zinc 1-y Ga y Sn 1-z X z (A: Ca, Ba, La, Eu; X: Si, Sb), Ca 1-x A x Al 2-y TM y The TEG may comprise at least one material selected from the group consisting of Si2 (A=Sr, Ba; T=Mn, Zn). The TEG may have a thickness of 2 mm to 50 mm, preferably 2 mm to 30 mm, more preferably 5 mm to 30 mm.

[0120] The energy recovery shell 130 may include multiple thermoelectric modules.

[0121] The TEG may be in a flat or annular configuration, for example, as described in Mengjun Zhang et al., “Performance Comparison of Annular and Flat Plate Thermoelectric Generators for Cylindrical Hot Sauce,” https: / / doi.org / 10.1016 / j.egyr.2021.01.008,2352-4847 / 2021, published by Elsevier Ltd. The shape and / or modularity of the TEG may depend on the shape of the reaction tube 112 and / or the expected temperature difference.

[0122] The device 110 may include at least one energy storage means, shown as an electrical resistor 132 in Fig. 1a and Fig. 1b, for absorbing electrical energy from the energy recovery shell 130, and / or at least one supply to a consumer for supplying electrical energy from the energy recovery shell 130. The consumption may be complete or at least partial. The consumption may include storage. The consumption may include conversion of electrical energy into another form of energy. The TEG may be configured to be able to draw electrical energy directly. The device 110 may thus be configured such that the temperature directly at the TEG is not too high and at the same time not too low. The TEG material used may be stable over a temperature range, in particular at the temperature to which the feedstock is heated. Alternatively or additionally, the device 110 may have further elements for protecting the TEG, for example for cooling or pre-cooling. The temperature may thus be adjusted depending on the material of the TEG.

[0123] The reaction tube 112 and the energy recovery shell 130 may be in a concentric arrangement. The reaction tube 112 may be the inner tube and the energy recovery shell 130 may be further arranged on the outside. For example, the energy recovery shell 130 may be the outer shell of the device 110 as shown in Figures 1a, 1b, 2a, 2b, 3a and 3b. However, other designs are also contemplated. For example, the device 110 may additionally have a cooling shell 146 that at least partially surrounds all the tubes of the device 110 as shown in Figures 5a and 5b.

[0124] The apparatus 110 may include multiple heating zones 144. For example, the apparatus 110 may have two or more heating zones 144. Each heating zone 144 may include at least one heating shell 129. The heating shells 129 may be connected by an electrical connection 133. The apparatus 110 may also have regions without heating of the feedstock, such as a mere transport zone. Figures 3a and 3b show an embodiment with two heating zones 144. For example, the two heating zones may be configured as two reactors or two heat transferers, or one reactor and one heat transferer. For the configuration of further elements of the apparatus 110 in Figure 3a, reference may be made to the description of Figure 1a, and for the configuration of further elements of the apparatus 110 in Figure 3b, reference may be made to the description of Figure 1b. In Figure 3a, the reaction tube 112 is configured as a metal cylinder with an external arrangement of a TEG. In Figure 3b, the reaction tube 112 is configured as a ceramic cylinder with an external arrangement of a TEG.

[0125] 4a to 4y show examples of embodiments and variations of the apparatus 110 with a building kit with tube types for possible reaction tubes 112. As mentioned above, the apparatus 110 may have multiple reaction tubes 112. The reaction tubes 112 may be of different configurations, for example, with respect to diameter and / or length and / or shape. The reaction tubes 112 may include symmetrical and / or asymmetrical pipes and / or combinations thereof. In a purely symmetrical configuration, the apparatus 110 may be equipped with reaction tubes 112 of the same tube type. The tube type may be characterized by at least one feature selected from the group consisting of the horizontal configuration of the tubes, the vertical configuration of the tubes, the length of the inlet (l1) and / or outlet (l2) and / or transition (l3), the diameter of the inlet (d1) and outlet (d2) and / or transition (d3), the number of passes n, the length per pass, the diameter per pass, the shape, the surface and the material. The apparatus 110 may include a combination of at least two different tube types connected in parallel and / or in series. For example, the apparatus may be equipped with tubes of different lengths at the inlet (l1) and / or outlet (l2) and / or transition (l3). For example, the apparatus 110 may be equipped with tubes with asymmetric diameters at the inlet (d1) and / or outlet (d2) and / or transition (d3). For example, the apparatus 110 may be equipped with tubes with different numbers of passes. For example, the apparatus may be equipped with tubes with passes with different lengths per pass and / or different diameters per pass. In principle, any combination of any tubes in parallel and / or series is conceivable. The apparatus 110 may be equipped with multiple inlets 120 and / or outlets 122 and / or production streams. Reactor tubes 112 of different or the same tube types may be arranged in parallel and / or series with multiple inlets 120 and / or outlets 122. Possible tubes for the reaction tubes 112 may take the form of various tube types in the form of a building kit 134, which may be selected and combined as needed depending on the end application. The use of tubes of different tube types can allow for more precise temperature control and / or tuning of the reaction when feed is fluctuating and / or selective yield of the reaction and / or optimized methodology. The tubes can have the same or different shapes and / or surfaces and / or materials.

[0126] Figures 4a to 4y show schematic diagrams of possible embodiments as examples of tube or cylinder types, which can be divided into the following categories, all possible combinations of the categories being possible: Category A refers to the course of the reactor tubes 112 and / or tube segments 114, A1 refers to tubes or cylindrical types with a horizontal course and A2 refers to tube types with a vertical course, ie a course perpendicular to a horizontal course. Category B specifies the ratio of the length of the inlet (l1) and / or outlet (l2) and / or the diameter of the inlet (d1) and / or outlet (d2) and / or transition (d3), with six different possible combinations being provided in the building kit 134. Category C denotes the ratio of the inlet (l1) and / or outlet (l2) lengths to the path length, where all combinations are considered and are labeled Ci in this case. Category F includes the number of electrodes, F1 indicates that the number of electrodes is ≦2, for example for DC or AC power supplies, F2 indicates that the number of electrodes is >2, for example for three-phase power supplies.

[0127] Figures 4b to 4y show examples of the present invention of combinations of reactor tubes 112 and / or tube segments 114 of the same and / or different tube types. Figure 4b shows a combination of reactor tubes 112 with three horizontal pipelines 112 and / or pipeline segments 114 of tube type A1, arranged in series. Figure 4c shows two vertical tubes of tube type A2 connected in parallel, as well as one downstream reactor tube 112 and / or one downstream pipeline segment 114, similar to tube type A2. Figure 4d shows multiple reactor tubes 112 and / or pipeline segments 114 of tube type A2, all connected in parallel. Figure 4e shows an embodiment in which multiple tube types of category B are arranged in series. The reactor tubes 112 and / or pipeline segments 114 may be the same or different tube types of category B, here identified by Bi. Fig. 4f shows an embodiment with six reactor tubes 112 and / or pipeline segments 114 of category B, in each case arranged in two parallel strands of two reactor tubes 112 and / or pipeline segments 114, with two further reactor tubes 112 and / or pipeline segments 114 connected downstream. Fig. 4g shows an embodiment with pipelines 112 and / or pipeline segments 114 of category C, with two pipelines 112 and / or pipeline segments 114 connected in parallel, with one reactor tube 112 and / or one pipeline segment 114 connected downstream. Mixed forms of categories A, B and C are also possible, as shown in Figs. 4h to 4m.

[0128] As discussed above, the apparatus 110 may include multiple inlets 120 and / or outlets 122 and / or production streams. Reactor tubes 112 and / or pipeline segments 114 of different or same tube types may be arranged in parallel and / or series with multiple inlets 120 and / or outlets 122, for example, as shown in Figures 4k and 4m.

[0129] 4n to 4p show an exemplary combination of reactor tubes 112 and / or pipeline segments 114 of categories A and Fi. 4q and 4r show an exemplary combination of reactor tubes 112 and / or pipeline segments 114 of categories B and Fi. 4s shows an exemplary combination of reactor tubes 112 and / or pipeline segments 114 of categories C and Fi. 4t shows an exemplary combination of reactor tubes 112 and / or pipeline segments 114 of categories A, B, C and Fi. 4u shows an exemplary combination of reactor tubes 112 and / or pipeline segments 114 of categories A, C and Fi. 4v shows an exemplary combination of reactor tubes 112 and / or pipeline segments 114 of categories B, C and Fi. 4w and 4y show an exemplary combination of reactor tubes 112 and / or pipeline segments 114 of categories A, B, C and Fi. Figure 4x shows an exemplary combination of reactor tubes 112 and / or pipeline segments 114 of categories A, B and Fi. Reactor tubes 112 and / or pipeline segments 114 of different or same tube types of categories A, B, C and Fi may be arranged in parallel and / or series with multiple inlets 120 and / or outlets 122. Examples of multiple inlets 120 and / or outlets 122 and / or production streams are shown in Figures 4o, 4p, 4r, 4s, 4v to 4y. Lines may represent feedstock flows but may also represent electrical connections.

[0130] 5a and 5b show an embodiment of the device of the invention with a cooling circuit comprising a cooling shell 146. The cooling shell 146 can be configured to at least partially surround the energy recovery shell 130. The cooling shell 146 can be configured to cool below room temperature. The cooling shell 146 can be configured to establish a temperature difference between the temperature of the reaction tube 112, in particular the temperature of the shell of the reaction tube 112, at a defined value, for example. The cooling shell 146 can have at least one cooling medium. For the configuration of further elements of the device 110 in FIG. 5a, reference can be made to the description of FIG. 1a, and for the configuration of further elements of the device 110 in FIG. 5b, reference can be made to the description of FIG. 1b. In FIG. 5a, the reaction tube 112 is configured as a metal cylinder. There is a TEG surrounded by the cooling shell 146 in a concentric arrangement on the outside. In FIG. 5b, the reaction tube 112 is configured as a ceramic cylinder. There is a TEG surrounded by the cooling shell 146 in a concentric arrangement on the outside.

[0131] Figures 6a, 6b, 7a and 7b show an embodiment in which the tubes of the device 110 apart from the reaction tube 112 or the reaction tube 112 have a rectangular shape. The reaction tube 112 in these figures is also configured as a hollow cylinder. Figure 6a shows an embodiment similar to the device 110 of Figure 1a. Figure 6b shows an embodiment similar to the device 110 of Figure 2a. Figures 7a and 7b show an embodiment with an additional cooling shell 146. Figure 7a shows an embodiment similar to the device 110 of Figure 5a. Figure 7b shows a configuration similar to the one in Figure 7a, but with multiple reaction tubes 112.

[0132] Figures 8a to 8d show examples of the use of the device. Purely by way of example, the device 110 in Figures 8a to 8d is shown similarly to the device 110 in Figure 1a. However, any other described embodiment of the device 110 is conceivable. As mentioned above, the device 110 may include at least one energy storage means for absorbing electrical energy from the energy recovery shell 130, and / or at least one supply to a consumer for supplying electrical energy from the energy recovery shell 130, shown diagrammatically by an electrical resistor 132. In Figure 8a the consumer is shown as any consumer 148. The consumer 148 may for example be one or more of a charging station, a light, another reactor or any other consumer. Examples are a heat exchanger, a heat transferer, an energy storage means, a battery or an accumulator. Figure 8b shows a consumer in the form of a further device 110, which may for example use the energy to heat a heating shell of the further device 110. Fig. 8c shows an example of two devices 110 (each similar to device 110 of Fig. 1a), each configured to supply recovered energy to an electrical resistor 132, which can be used, for example, to heat the respective other reactor. Fig. 8d shows an example with multiple identical or different consumers 148 that can be at least partially powered by the recovered energy. Other uses of the recovered energy are also conceivable. [Explanation of symbols]

[0133] 110 Equipment 111 Reaction Space 112 Reaction tube 114 Pipe Segments 118 Tube System 120 Entrance 122 Exit 124 Galvanic Insulators 126 Voltage / Power Supply 127 Electrical Inputs and Outputs 128 Electrical terminal 129 Heated Shell 130 Energy Recovery Shell 132 Electrical Resistors 133 Electrical Connection 134 Building Kit 144 Heating Zone 146 Cooling Shell 148 Voluntary Consumer

Claims

1. 1. An apparatus (110) comprising a number of tubes, at least one of said tubes configured as a reaction tube (112) for flowing at least one feedstock, said apparatus (110) having at least one energy recovery shell (130) at least partially surrounding said reaction tube (112), said energy recovery shell (130) having at least one thermoelectric generator configured to convert heat into electrical energy.

2. The apparatus (110) of claim 1, wherein the energy recovery shell (130) is configured to convert heat generated in an exothermic reaction in the reaction tubes (112) into electrical energy.

3. The apparatus (110) of claim 1 or 2, wherein the exothermic reaction proceeds during decoking and / or oxidation of deposits in the reactor tubes (112).

4. The apparatus (110) of any one of claims 1 to 3, wherein the energy recovery shell (130) comprises at least one material having a thermoelectric figure of merit ZT of 0.5 or more, preferably 0.8 or more, more preferably 1 or more.

5. The energy recovery shell (130) may be made of any one of lead telluride (Pb-Te), at least one telluride, at least one silicone, at least one silicate, at least one silicide, at least one Si-Ge silicide, at least one polymer, at least one ceramic, at least one skutterudite, CoSb3 skutterudite, germanium, at least one semi-Heusler alloy, Mg ２ (Sn, Si), Sr １－ｘ A ｘ Zinc １－ｙ G ｙ Sn １－ｚ X ｚ (A: Ca, Ba, La, Eu; X: Si, Sb), Ca １－ｘ A ｘ A ２－ｙ T.M. ｙ S ２ 5. The apparatus (110) of any one of claims 1 to 4, comprising at least one material selected from the group consisting of: (A=Sr, Ba; TM=Mn, Zn).

6. The apparatus (110) of any one of claims 1 to 5, wherein the energy recovery shell (130) comprises a number of the thermoelectric modules.

7. 7. The apparatus (110) of any one of claims 1 to 6, wherein the reaction tube (112) and the energy recovery shell (130) are in a concentric arrangement, the reaction tube (112) being an inner tube and the energy recovery shell (130) being further disposed on the outside.

8. 8. The apparatus (110) of any one of claims 1 to 7, wherein the reaction tube (112) comprises at least one material selected from the group consisting of at least one ferritic material, at least one austenitic material, at least one metal, at least one metal alloy, copper, aluminum, iron, steel alloys, Cr-alloys and / or Ni-alloys, graphite, carbon, carbides, silicides, or the reaction tube (112) is configured as a ceramic tube.

9. 9. The apparatus (110) according to any one of claims 1 to 8, wherein the apparatus (110) comprises at least one electrically conductive heating shell (129), the apparatus (110) comprising at least one current or voltage source (126) configured to generate an electric current in the heating shell (129), the heating shell heating the reaction tube (112) by Joule heat generated when the electric current passes through the heating shell (129).

10. 10. The apparatus (110) of any one of claims 1 to 9, wherein the heating shell (129) at least partially surrounds the reaction tube (112), the heating shell (129) directly surrounds the reaction tube (112) and is configured to emit its heat generated by an electric current to the reaction tube (112), and / or the apparatus (110) comprises at least one galvanic insulator (124), the galvanic insulator (124) being disposed between the reaction tube (112) and the heating shell (129), the galvanic insulator (124) being configured to galvanically insulate the reaction tube (112) from the heating shell (129) and to transfer heat from the heating shell (129) to the reaction tube (112).

11. 11. The apparatus (110) of claim 1, wherein the apparatus has at least one cooling shell (146) configured to at least partially surround the energy recovery shell (130), the cooling shell (146) configured to cool to below room temperature.

12. 12. The apparatus (110) of any one of claims 1 to 11, wherein the apparatus (110) is configured to heat the feedstock to a temperature in the range of 200°C to 1700°C, preferably 300°C to 1400°C, more preferably 400°C to 875°C.

13. 13. The apparatus (110) of any one of claims 1 to 12, wherein the feedstock comprises at least one medium selected from the group consisting of air, at least one oxygen-containing medium, water, water steam, and at least one oxidizing medium.

14. 14. The apparatus (110) of any one of claims 1 to 13, wherein the reaction tube (112) is configured to receive at least one feedstock for carrying out at least one endothermic reaction.

15. A plant comprising at least one apparatus (110) according to any one of claims 1 to 14, said plant being selected from the group consisting of plants for carrying out at least one endothermic reaction, plants for heating, plants for preheating, steam crackers, steam reformers, apparatuses for alkane dehydrogenation, reformers, apparatuses for dry reforming, apparatuses for styrene production, apparatuses for ethylbenzene dehydrogenation, production of acetylene, crackers, catalytic crackers, apparatuses for dehydrogenation.

16. A method for recovering electrical energy using a device (110) according to any one of claims 1 to 15, said method comprising the steps of: passing said feedstock through said reactor tube (112); converting heat generated in the reaction tubes (112) during chemical reactions into electrical energy using the thermoelectric generators of the energy recovery shell (130); A method comprising:

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