Reactor and method for carrying out chemical reactions

Abstract

The present invention relates to a reactor (100, 200) for carrying out a chemical reaction, comprising a reaction vessel (10) and one or more reaction tubes (20), wherein one or more power input elements (41) are guided into the reaction vessel (10) for electrical heating of the one or more reaction tubes (20), the one or more power input elements (41) each having a rod-shaped portion (43) that extends through a wall (14) of the reaction vessel (10) into a wall passage (15). A connecting chamber (60) from which the rod-shaped portions (43) protrude is arranged outside the reaction vessel (10) adjacent to the wall (14) of the reaction vessel (10), and the wall passage (15) is provided in which the rod-shaped portions (43) extend through the wall of the reaction vessel. Gas supply means (80-82) are provided which are configured to add inert gas to the connecting chamber (60), and the wall passage (15) in which the rod-shaped portion (43) is accommodated in a longitudinally movable manner is designed to be gas permeable so that at least a portion of the inert gas supplied into the connecting chamber (60) flows into the reaction vessel (10). A corresponding method is also the subject of the present invention.

Description

[Technical Field]

[0001] The present invention relates to a reactor and a method for carrying out chemical reactions according to the preambles of the independent claims. [Background technology]

[0002] Many processes in the chemical industry use reactors in which one or more reactants pass through heated reaction tubes, where they react catalytically or non-catalytically. Heating serves, among other things, to overcome the activation energy required for the ongoing chemical reaction. The reaction may proceed entirely endothermically or, after the activation energy has been overcome, exothermically. The present invention is particularly concerned with strongly endothermic reactions.

[0003] Examples of such processes are steam cracking, various reforming processes, in particular steam reforming, dry reforming (carbon dioxide reforming), mixed reforming processes, alkane dehydrogenation processes, etc. In steam cracking, the reaction tubes are guided through the reactor in the form of a coil with at least one U-shaped bend in the reactor, while tubes extending through the reactor without a U-shaped bend are usually used in steam reforming.

[0004] The present invention is suitable for all such processes and reactor tube designs. The articles "Ethylene", "Gas Production", and "Propene" in the Ullmann Encyclopedia of Industrial Chemistry, for example, in the April 15, 2009 publication, DOI: 10.1002 / 14356007.a10_045.pub2, the December 15, 2006 publication, DOI: 10.1002 / 14356007.a12_169.pub2, and the June 15, 2000 publication, DOI: 10.1002 / 14356007.a22_211, are referenced here purely for illustrative purposes.

[0005] The reaction tubes of the corresponding reactor are conventionally heated using burners, in which case the reaction tubes are passed through a combustion chamber in which the burners are also arranged.

[0006] However, as described, for example, in DE 10 2015 004 121 A1 (as well as EP 3 075 704 A1), there is currently an increasing demand for synthesis gas and hydrogen, for example, produced with or without reduced local carbon dioxide emissions. However, this demand cannot be met by processes that typically use combustion reactors, typically by burning fossil energy carriers. Other processes are ruled out, for example, due to high costs. The same applies to the production of olefins and / or other hydrocarbons by steam cracking or dehydrogenation of alkanes. Even in such cases, processes that at least emit a low amount of carbon dioxide on-site are desirable.

[0007] Against this background, the aforementioned DE 10 2015 004 121 A1 proposes electrical heating of a steam reforming reactor in addition to combustion. In this case, one or more voltage sources are used, providing three-phase AC voltage to three external conductors. Each external conductor is connected to a reactor tube. A star circuit is formed, with a star point realized by a collector, to which the pipeline opens and the reactor tube is electrically connected. In this way, the collector ideally remains potential-free. The collector is positioned below and outside the combustion chamber, preferably extending transversely, i.e., horizontally, relative to the vertical line. WO 2015 / 197181 A1 also discloses a reactor in which the reactor tubes are arranged in a star point circuit.

[0008] In addition to direct heating of the reactor tubes by passing an electric current through them, there are a variety of concepts for indirect electrical heating of the reactor tubes. Indirect electrical heating can take the form of external electrical heating, as described, inter alia, in WO 2020 / 002326 A1. Internal heating is also possible, as disclosed, for example, in WO 2019 / 228798 A1. In addition to resistive or impedance heating, induction electrical heating of the reactor tubes or catalyst beds can be performed, as described, for example, in WO 2017 / 072057 A1. Induction heating can be achieved, for example, by heating internal or external heating elements or the reactor tube itself. Direct (non-inductive) heating of the reactor tubes is also disclosed in DE 10 2015 004 121 A1. The basic concepts for heating can be realized with multi-phase or single-phase alternating current or direct current. In the case of direct heating of the reactor with direct current or single-phase alternating current, a star circuit with a potential-free star point cannot be realized, but the power input can be realized in basically the same way. The invention is suitable for all variants of electric heating.

[0009] WO 2004 / 091773 A1 describes an electrically heated reactor for carrying out gas reactions at high temperatures. The reactor is composed of a reactor block, one or more monolithic modules of a material suitable for electrical heating, surrounded by a housing with channels extending through the modules and designed as reaction channels, and a device for conducting or inducing electric current in the reactor block. The safety during operation of such a reactor is enhanced in that the housing of the reactor block has a double-walled jacket that hermetically seals the reactor block and at least one device for supplying an inert gas to the double-walled jacket.

[0010] As will also be explained below, in the case of electrically heated reactors, special safety-related aspects must be observed. The aim of the present invention is to take these aspects into account and thus to identify measures which allow advantageous operation of electrically heated reactors. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] WO 2020 / 002326 A1 [Patent Document 2] WO 2019 / 228798 A1 [Patent Document 3] WO 2017 / 072057 A1 [Patent Document 4] DE 10 2015 004 121 A1 [Patent Document 5] WO 2004 / 091773 A1 [Non-patent literature]

[0012] [Non-Patent Document 1] Ullman Encyclopedia of Industrial Chemistry, DOI:10.1002 / 14356007.a10_045.pub2, April 15, 2009 [Non-patent document 2] Ullman Encyclopedia of Industrial Chemistry, DOI:10.1002 / 14356007.a12_169.pub2, December 15, 2006 [Non-patent document 3] Ullman Encyclopedia of Industrial Chemistry, DOI:10.1002 / 14356007.a22_211, June 15, 2000 Summary of the Invention

[0013] Against this background, the present invention proposes a reactor and a method for carrying out chemical reactions according to the preambles of the independent claims. Embodiments are the subject of the dependent claims and the following description.

[0014] In the electrified furnace concept underlying the present invention (the term "furnace" is generally understood to denote the corresponding reactor or at least its insulated reaction space), for example, the reaction tubes or corresponding tube segments (hereinafter also referred to as "tubes" for short) themselves are used as electrical resistors for generating heat. This approach has the advantage of being more efficient and allowing a higher achievable heat flux density compared to indirect heating by external electrical heating elements. However, as mentioned at the outset, any other type of electrical heating (direct or indirect, in the form of resistance, impedance or induction heating, by single-phase or multi-phase alternating current or by direct current) can also be carried out within the scope of the present invention, if such heating proves to be advantageous.

[0015] When heating with multiphase alternating current, the current is supplied to the directly heated reactor tubes via M separately connected phases. The conductive reactor tubes connected to the M phases can also be electrically connected at a star point. The number of phases M is preferably 3, which corresponds to the number of phases in a conventional three-phase current power supply or network. However, in principle, the invention is not limited to the use of three phases and can also be used with a greater number of phases, for example 4, 5, 6, 7, or 8. The phase offset is preferably 360° / M, i.e., 120° relative to the three-phase current.

[0016] In electrical heating with multiphase alternating current, the equalization of potentials between the phases is achieved by a star circuit at the star point, which eliminates the need for electrical insulation of the connected pipelines. This represents a particular advantage of such furnace concepts, since the destruction of metal reactor tubes to insulate certain sections is undesirable, especially at the high temperatures used and the high material and construction costs involved.

[0017] However, the measures proposed by the present invention and described below are equally suitable for use with single-phase AC and DC current, and the present invention can be used in both AC-heated and DC-heated reactors, or in corresponding mixed configurations. As mentioned above, the present invention is also suitable for use with indirectly heated reactor tubes. In the case of a DC configuration, only the type of current source and the power input or the area of ​​the reactor tube facing the corresponding section to which current is supplied differ from the AC configuration, for example. In the latter, electrical connections between different tube sections are only performed optionally. Since no potential-free star points exist in the DC configuration, it is necessary to provide appropriate current discharge elements that safely return the current flow to the outside. The latter can be designed in the same way as the power input, as described below.

[0018] In the terms of the claims, the invention relates to a reactor for carrying out chemical reactions, having a reaction vessel (i.e. an insulated or at least partially insulated region) and one or more reaction tubes, in which one or more power input elements are guided into the reaction vessel for electrical heating of the reaction tubes. According to the invention, the power input element has a rod-shaped portion or several power input elements each have a rod-shaped portion, which extend in a wall passage or respectively through the wall of the reaction vessel in a wall passage.

[0019] Within the scope of the present invention, the connection chamber from which the rod-shaped portion protrudes is arranged adjacent to the wall outside the reaction vessel, and the rod-shaped portion of the current input element extends through this wall, i.e., a wall passage is formed therein. (Hereinafter, the plural form is used only for simplicity and does not imply any intended limitation, but the description applies equally to individually existing elements.) The rod-shaped portion is connected in the connection chamber to a flexible contact element, in particular, a strand, a power strip, a lamella strip, or a current spring, for example, via a suitable intermediate portion or intermediate element. These flexible contact elements are fixed with their ends not connected to the rod-shaped portion to rigid contact elements, which are usually arranged in an insulated manner, for example, by the wall, so that they cannot move within the connection chamber, and are powered, for example, by a DC or AC converter. The flexible contact element compensates for the longitudinal movement of the rod-shaped portion within the wall passage. In other words, the rod-shaped portion is accommodated in the wall passage so that it can move longitudinally.

[0020] Within the scope of the present invention, the wall passage having a rod-shaped portion housed inside in a longitudinally movable manner is designed to be gas permeable, i.e. to allow constant movement of gas from the reaction vessel to the connecting chamber and vice versa.

[0021] According to the present invention, the inert gas, which is at least partially supplied to the connecting chamber and flows through the wall passage into the reaction vessel, is supplied to the connecting chamber by a correspondingly configured gas supply means, which may include, for example, a supply nozzle or opening, a line, and a gas reservoir connected thereto. The inert gas is at least partially supplied into the connecting chamber. The supply to the connecting chamber has the advantageous effect that the connecting chamber is flushed, an additional cooling effect is achieved in the connecting chamber, and a flushing flow that is as directed as possible from bottom to top in the reaction vessel is achieved. For example, additional supply points can be provided at any point to further improve the flushing flow in the reaction vessel, in particular to avoid dead zones where oxygen may accumulate.

[0022] The invention will be further described below with reference to an embodiment in which multiple tube sections of one or more reaction tubes extend in each case between a first and a second region in the reaction vessel, passing through an intermediate region between the first and second regions, and in which, for electrical heating of the tube sections, the tube sections in the first region are each electrically connected or connectable to one or more power connections of a power source, as will be described in detail below, i.e., to one or more DC connections in the case of a DC configuration, or to phase connections ("external conductors") of a polyphase AC power source in the case of an AC configuration. In the case of indirect heating, which can also be used as described above and which is also possible, connection elements for a corresponding heating device are guided through the wall of the reaction vessel.

[0023] As previously mentioned, in a corresponding embodiment of the present invention, the respective AC voltages are provided by an AC configuration via phase connections, with the AC voltages of the phase connections being phase-shifted in the manner described above. For example, a supply network or a suitable generator and / or transformer can serve as the AC power source. The tube sections form a star circuit and are conductively coupled to each other at their ends opposite the current source, i.e., at the second region.

[0024] On the other hand, in a DC configuration, in other embodiments, the same or different electrostatic potentials are supplied via one or more DC connections, and current recovery elements are provided at each end opposite the power input. The same is true when using single-phase AC current from one or more current sources.

[0025] In the intermediate region, the tube sections in the mentioned embodiment of the invention extend through the reaction vessel in particular freely, i.e. without mechanical support, without electrical contacts and / or without fluid or purely mechanical cross-connections to one side. In this embodiment, the tube sections extend in particular substantially or completely straight in the intermediate region, where "substantially straight" should be understood to mean that there is an angular deviation of less than 10° or 5°.

[0026] In particular, the cleavage reaction in steam cracking is a strongly endothermic reaction, so that the supply of the energy required for the reaction by direct heating (ohmic resistance) requires a high current intensity, which is provided in the reactor concept described above by one or more transformers located outside the reactor.

[0027] In all of the electrical heating concepts mentioned above, the current must be conducted from the outside to the inside of the adiabatic reactor and to the process conduction areas with as low losses (low electrical resistance) as possible.

[0028] To reduce heat losses and achieve high system efficiency, it is essential to place the electrically heated reactor tubes in an insulated box (herein called the reactor vessel). When penetrating the insulated walls of the reactor vessel, the current conductor must overcome sub-adiabatic zones without the development of unacceptably high local temperatures in these areas.

[0029] Therefore, within the scope of the particularly preferred embodiment of the invention described, a power input arrangement is provided in the first area of ​​the reactor, i.e., the area of ​​power input, to which each tube section or each group of tube sections is electrically connected. The tube sections are provided in such a number that each one or each group of several tube sections is connected to each one of the power input arrangements, and vice versa. The number of power input arrangements provided within the scope of the invention depends on the number of phase connections of the polyphase AC power supply in the case of an AC arrangement, or this number corresponds to the number of DC connections.

[0030] Each power input element has at least one of the aforementioned rod-shaped portions, each of which extends through the wall of the reactor vessel in its wall passage. In contrast to strands or the like, for example, the rod-shaped portions in all embodiments of the present invention are in particular integrally formed (i.e., not in the form of parallel or intertwined wires). The rod-shaped portions can be designed as solid or at least partially tubular, i.e., hollow rods. The rod-shaped portions have a longitudinal extension perpendicular to the reactor vessel wall that is at least twice, in particular at least three, four, or five times, for example up to ten times, their maximum transverse extension parallel to the reactor vessel wall. The rod-shaped portions can, for example, be circular, elliptical, triangular, or polygonal in cross section, or can have any other shape.

[0031] In all embodiments of the present invention, the inert gas can be a gas or gas mixture having a superatmospheric content of nitrogen, carbon dioxide, and / or argon, respectively, or the gas supply means is configured to provide the corresponding inert gas. In particular, the content can be greater than 50%, 60%, 70%, 80%, or 90%. Thus, it is not necessary for the inert gas to be a pure "inert gas" in the traditional sense; rather, it is sufficient if the inert gas at least partially reduces the flammability range of the mixture, particularly due to the content of non-flammable gases, i.e., reduces the risk of fire, explosion, or implosion. Inert gases for use within the framework of the present invention can in particular have a reduced oxygen content, e.g., an oxygen content of less than 10%, 5%, 1%, 0.5%, or 0.1%. The inert gas can also be (substantially) oxygen-free.

[0032] Due to the supply of inert gas carried out according to the invention, the invention makes it possible to movably accommodate the rod-shaped part of the power input element in the wall of the reaction vessel without the need for an airtight seal, which would be necessary to avoid flammable gases leaking into the environment, for example, if the reaction tube is damaged ("coil shredder"). Within the scope of the invention, the wall passage can therefore be permanent, since it is significantly more compact and does not require sealing material. The advantage here is that all components emerging from the connection chamber into the environment have very little compensating movements, as a result of which the implementation of airtightness with respect to the reaction vessel wall itself is greatly simplified here.

[0033] Because the combustible gases emerging from the reaction tubes in the combustion reactor in the form of a hydrocarbon vapor mixture react immediately and continuously with combustion occurring in the reaction vessel or corresponding combustion chamber, or because the oxygen content present in other areas of the reaction vessel is significantly reduced due to the occurrence of combustion, and the gas space surrounding the reaction tube is already essentially "inerted," coil shredders present fewer safety-related problems in conventional combustion reactors than purely electrically heated reactors used in accordance with the present invention. In contrast, in the case of purely electrically heated reactors, the corresponding combustible gases accumulate in the reaction vessel, where they may reach the limit of explosion or implosion, for example, at temperatures exceeding the normal oxygen content of air and the autoignition temperature. Even in the case of combustion without implosion, the energy input from complete or incomplete combustion can lead to overheating. The complete or incomplete combustion itself, along with the amount of gases exiting the reaction tubes, can also result in a significant pressure increase. This pressure increase is reduced because the use of inert gas prevents or at least significantly limits combustion of the exiting gas mixture.

[0034] However, by specifically providing an inert gas in the connecting chamber or (at least) by adding an inert gas to the connecting chamber, the invention achieves the already mentioned further advantage that the wall seal between the connecting chamber and the reaction vessel does not have to be designed to be completely gastight, which can only be achieved at high temperatures and at very high material costs, for example by using a heat-resistant bellows structure, etc. As a result of the advantageous continuous outflow of inert gas from the connecting chamber to the reaction vessel, convective heat dissipation can also be achieved and therefore cooling of the connecting chamber or support of an existing cooling can be achieved.

[0035] As mentioned above, it is advantageous for the compensation movements occurring outside the connecting chamber and the reaction vessel to be very small. Therefore, according to one embodiment of the present invention, the reaction vessel and the connecting chamber are housed together in an airtight manner, optionally with the exception of one or more target outlets, for example in the form of one or more chimneys. In this case, the term "target outlet" is intended to mean an outlet that is or can be opened in a targeted manner for gas leakage, for example, a permanently open outlet opening or a gas outlet flap that opens due to an internal pressure increase and can function as a check valve. A "target outlet" is different from an opening resulting from unavoidable leakage. The airtight container can be provided using a separate outer container (containment container), which separately surrounds the reaction vessel and the connecting chamber, each having its own outer wall. However, it can also be advantageous to design the outer wall of the reaction vessel and the connecting chamber in an airtight manner, with the exception of a wall in which the rod-shaped portion of the power input element is housed in a longitudinally movable manner in a wall passage, and again, with the exception of the target outlet.

[0036] As mentioned above, the reactor vessel may have one or more target outlets that can be connected to one or more chimneys. In this case, the chimney(s) may be sized to reduce the excess pressure caused by the aforementioned effects and achieve a slight negative pressure within the reactor vessel as a result of the chimney effect. A system that is inerted to a certain extent and "open" to the environment (as a result of the chimney) can limit the rate of pressure increase within the reactor vessel to an acceptable amount in the event of hydrocarbon leakage as a result of damage to the reactor tube. The use of inert gas in the method according to the present invention, which includes continuous flushing with a relatively small amount of inert gas, ensures that there is no backflow of ambient air into the reactor vessel and connecting chambers. In addition, this method can compensate for the intrusion of small amounts of false air due to insufficient sealing.

[0037] The proposed concept of chambers (reaction vessel and connecting chambers) filled with inert gas makes it possible to reduce the oxygen content in these chambers. The reaction rate of the escaping hydrocarbons, and therefore the rate of significant additional volume increase (as a result of the reaction heat input), as can be utilized according to the invention, correlates, in a first approximation, with the oxygen partial pressure. This correlation is summarized in Table 1 below: where γO2 represents the oxygen partial pressure and V reac represents the reaction-related volume increase rate.

[0038] [Table 1]

[0039] Maximum allowable pressure p max depends on the mechanical stability of the respective chamber or surrounding confinement. This pressure is the pressure in the relevant chamber volume V in the case of a coil shredder or other corresponding safety-related event. box , chimney diameter D chimney , and the pressure p, which depends on the oxygen partial pressure box It must be at least as large as p max ≧p box =f(V box ,Dchimney ,γO2)

[0040] This requirement is the design criterion for sizing the chimney, i.e., open communication to the environment, and vice versa. This relationship is illustrated again in Figure 6 below. For example, as illustrated by dashed lines 601 and 602 in Figure 6, if a maximum allowable pressure rise of 20 mbar is used here as a criterion, the volume increase associated with the reaction would be approximately 10 mbar, in order to be able to use a chimney (dashed line 601) with a diameter of 500 mm. 3 / s, resulting in a maximum oxygen content of about 1%, which is adjusted by inerting. Conversely, if inerting to an oxygen content of at most 1% is performed, a chimney diameter of at least 500 mm must be used. To be able to use a chimney with a diameter of 900 mm (dashed line 602), the volume increase associated with the reaction is about 42 m 3 / s, resulting in a maximum oxygen content of approximately 4%, which is regulated by inerting. Conversely, and similarly to the explanation above, if inerting to a maximum oxygen content of 4% is used, a chimney diameter of at least 900 mm must be used.

[0041] The lower the oxygen content in the relevant chamber, the smaller the volume increase, and as a result the diameter of the emergency chimney, which requires the evacuation of the additional volume, can also be reduced. What is important for an efficient limitation of the oxygen content is always a sufficiently good seal against the environment, in order to avoid as much as possible or to a great extent the intrusion of oxygen-laden false air.

[0042] In other words, within the framework of the present invention, the maximum oxygen content in the reaction vessel and / or the connecting chamber is adjusted by an inert gas, and this maximum oxygen content is selected based on the dimensioning of the chimney or chimneys, or the gas supply means is set to supply an inert gas or to adjust the oxygen content based on this.

[0043] The amount of inert gas supplied can be regulated by corresponding regulation means, in particular based on oxygen measurements in one or more chimneys, so that the oxygen content can be kept constant during operation. Corresponding safety concepts can also include, for example, that operation of the reactor is prevented or continues to be prevented if the measured oxygen content exceeds a target oxygen content. For example, the supply of hydrocarbons to the reaction tubes and / or their heating can be released only if the required oxygen content falls below the required level. If a fault is detected, the reaction operation can generally be prevented by adding hydrocarbons to the reaction tubes.

[0044] Unacceptable leakage of gas from the reactor tubes can be detected, for example, via a pressure measurement sensor, and if a gas leakage is detected, the supply of hydrocarbons to the reactor tubes can be prevented in order to minimize the total leakage of hydrocarbons.

[0045] The hydrocarbon content (e.g. in the form of carbon monoxide equivalents) in the stack can also be measured continuously in order to detect very small damages (leakage flows without sudden pressure increases). Likewise, unacceptable values ​​can result in the avoidance of hydrocarbon supply.

[0046] Thus, the invention can more generally encompass determining, based on pressure and / or hydrocarbon measurements, a value characterizing gas leakage from one or more reactor tubes in one or more chimneys, and initiating one or more safety measures if the value exceeds a predetermined threshold.

[0047] According to one embodiment of the invention, cooling panels through which a cooling fluid flows are provided in the connection chamber and are arranged between at least two or at least two groups of the rod-shaped portions protruding into the connection chamber.

[0048] The cooling panel in this embodiment of the invention is advantageously designed to be flat in at least one portion. That is, the cooling panel extends between two boundary surfaces spaced apart from one another, the distance between the boundary surfaces defining the thickness of the cooling panel, and the extension along the boundary surfaces is greater than 2, 5, 10, or 20 times this thickness. The boundary surfaces can be flat or curved, so that the cooling panel is flat and planar, but the cooling panel in this case can also be curved, so that it is flat and semi-cylindrical or partially cylindrically curved. Different cooling panels can also be of different dimensions or designs. The "boundary surfaces" are surfaces that define the maximum thickness of the cooling panel. The cooling panel does not need to contact these boundary surfaces over its entire surface.

[0049] These dimensions are adapted individually to each cooling panel, i.e. a first cooling panel can be arranged obliquely or perpendicular to a second cooling panel, and some cooling panels can be rotated relative to one another, in particular around an axis parallel to the longitudinal extension of the rod-shaped parts of the power input elements and perpendicular to the wall of the reactor vessel.

[0050] The cooling panel may be particularly configured so that the cooling fluid flows in a direction generally corresponding to a direction perpendicular or parallel to the rod-shaped portion, for example through corresponding supply and removal openings for the cooling fluid on the side parallel to the rod-shaped portion.

[0051] The thickness of the cooling panel may range from 0.5 cm to 10 cm, especially from 1 cm to 5 cm, at least in cross section dimensioned as described above.

[0052] In particular, the connection chamber in this embodiment of the invention can have side walls extending perpendicular to the reactor wall, and in either case, the rod-shaped portion of the power input element extends through the reactor wall within the wall passage. One or more additional cooling panels can be arranged on or parallel to at least one of the side walls. Like the cooling panels described above, these cooling panels can be designed with basic dimensions.

[0053] In particular, the connecting chamber can also have a bottom wall extending parallel to the wall of the reaction vessel, in either case the rod-shaped portion of the power input element extending through the wall of the reaction vessel, said element being arranged between said wall of the reaction vessel and the bottom wall of the connecting chamber, which can be designed as an at least partially hollow wall and can be configured to allow said or further cooling fluid to flow through it.

[0054] In the present invention, the described cooling, in addition to the corresponding dimensioning and design of the power input elements themselves, ensures that a sufficiently low temperature is maintained overall, especially for connecting highly conductive and / or flexible contact elements.

[0055] In particular, in cooperation with the inactivation proposed by the present invention, exceeding the critical temperature can be reliably avoided, thereby significantly increasing operational safety.

[0056] According to the present invention, as described above, the rod-shaped portions of the power input elements are each guided longitudinally movable in a wall passage through the reactor vessel wall. The freedom of movement ensured in this way is particularly advantageous for the mechanical behavior of the reactor tubes, which is primarily governed by the thermal expansion of the tubes by several decimeters during reactor operation. This freedom of movement reduces the bending loads on the reactor tubes that would occur in the case of rigid fixation. On the other hand, as described below, in the case of AC heating, the reactor tubes can be fixed in the second region to a rigid star bridge on the reactor roof, thus providing a stable suspension even with corresponding longitudinal mobility of the rod-shaped portions of the power input elements. Due to their advantageous dimensioning with a sufficiently high linear cross-section, the rod-shaped portions of the power input elements ensure reliable transverse guidance of the reactor tubes. On the other hand, as described above, due to the connections within the cooling chamber, particularly via flexible contact elements, the components exiting the cooling chamber to the environment have very little compensating movement. Passivation according to the present invention simplifies this embodiment, as mentioned several times above, since the wall passages themselves do not need to be airtight.

[0057] The present invention can be used in reactor tubes and reactors such as those used for steam cracking, which have several U-shaped bends within the reactor vessel. However, the present invention can also be used in other types of reactors, such as those used for steam reforming, as mentioned above, where the reactor tubes do not have U-shaped bends within the reactor vessel. The reactor proposed by the present invention can be used to carry out any endothermic chemical reaction.

[0058] The present invention also relates to a method for carrying out a chemical reaction using a reactor having a reaction vessel and one or more reaction tubes, wherein one or more power input elements are guided into the reaction vessel for electrical heating of the one or more reaction tubes.

[0059] In accordance with the present invention, a reactor is used in conjunction with which one or more power input elements each have a rod-shaped portion, each of the one or more rod-shaped portions extending through a wall of the reactor vessel into a respective wall passage.

[0060] The connecting chamber from which the rod or rod-like portion protrudes is arranged outside the reaction vessel and adjacent to the wall of the reaction vessel in which the wall passage is formed. Gas supply means configured to add inert gas to the connecting chamber is provided, and the wall passage, in which the rod-like portion is accommodated in a longitudinally movable manner, is designed to be gas permeable so that at least a part of the inert gas supplied into the connecting chamber flows into the reaction vessel.

[0061] In a particularly preferred embodiment of the invention, a reactor is used in which several of the one or more tube sections extend in each case between a first region and a second region in the reaction vessel, and the first regions for heating the tube sections are each electrically connected to one or more power connections of a current source.

[0062] In this embodiment, a reactor is used, the reactor having a power input arrangement in the first region to which each one or each group of the tube segments is electrically connected, each power input arrangement having one of the power input elements, each having a rod-shaped portion extending in a wall passage through the wall of the reactor vessel. A connection chamber from which the rod-shaped portion protrudes is arranged outside the reactor vessel adjacent to the wall of the reactor vessel, and the rod-shaped portion extends through this wall in the wall passage. The rod-shaped portion is housed in the wall passage in a longitudinally movable manner. The wall passage having the rod-shaped portion housed therein in a longitudinally movable manner is gas-permeable, and there is also provided a means according to the invention, configured to add an inert gas to the connection chamber and allow the inert gas to flow at least partially through the wall passage into the reactor vessel.

[0063] For further features and advantages of the corresponding method, in which a reactor according to one of the previously described embodiments of the invention is advantageously used, reference is made to the above description.

[0064] The present invention will be further elucidated below with reference to the accompanying drawings illustrating embodiments of the invention with reference to and comparison with the prior art. [Brief explanation of the drawings]

[0065] [Figure 1] FIG. 1 is a schematic diagram illustrating a reactor for carrying out chemical reactions according to an embodiment not in accordance with the present invention. [Figure 2] FIG. 2 is a schematic diagram illustrating a reactor for carrying out chemical reactions, according to an embodiment of the present invention. [Figure 3] FIG. 3 is a schematic diagram illustrating a reactor for carrying out a chemical reaction according to a further embodiment of the present invention. [Figure 4A] FIG. 4A is a partial view showing a reactor for carrying out chemical reactions according to a further embodiment of the present invention. [Figure 4B] FIG. 4B is a partial view showing a reactor for carrying out chemical reactions according to a further embodiment of the present invention. [Figure 5] FIG. 5 is a schematic diagram illustrating a reactor for carrying out a chemical reaction according to a further embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram illustrating the principle of chimney sizing according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0066] In the figures, elements that correspond to one another functionally or structurally are designated by the same reference numerals and will not be described repeatedly for the sake of clarity. Where components of a device are described below, the corresponding description also relates in each case to the method carried out thereby, and vice versa. The description of the figures repeatedly refers to AC heating. However, as mentioned above, the invention is also equally suitable for the use of DC for heating. Reference is made here to the above description.

[0067] FIG. 1 shows a schematic diagram of a reactor for carrying out chemical reactions according to an embodiment not according to the present invention.

[0068] Here, a reactor designated 300 is set up to carry out a chemical reaction. For this purpose, the reactor comprises, in particular, an insulated reactor vessel 10 and reactor tubes 20, the multiple tube sections of which, here designated 21 in only two cases, extend between a first zone 11' and a second zone 12' in the reactor vessel 10, respectively. The reactor tubes 20, which will be described in more detail below with reference to FIG. 2, are attached to the reactor vessel's ceiling or support structure by means of a suitable suspension 13. In the lower region, the reactor vessel may in particular comprise a furnace (not shown). Needless to say, in each case, several reactor tubes are provided here and there.

[0069] FIG. 2 shows a schematic diagram of a reactor, generally designated 100, for carrying out chemical reactions, according to an embodiment of the present invention.

[0070] The zones previously designated by 11' and 12' now take the form of regions 11 and 12, and the tube sections 21 for heating within the first region 11 can in each case be electrically connected to phase connections U, V, W of a polyphase AC power supply 50. Specific types of connections, such as switches, are not illustrated.

[0071] In the embodiment of the invention illustrated herein, the tube segments 21 are integrally connected to one or more reaction tubes 20 and are conductively connected to each other in the second region 12 by connecting elements 30 disposed within the reaction vessel 10. A neutral conductor may also be connected to the tube segments.

[0072] Thus, in the reactor 100 illustrated here, several pipe sections 21 of the reaction tubes 20 (although several such reaction tubes 20 may be provided) are arranged side by side within the reaction vessel 10. The pipe sections 21 meet each other via U-shaped bends 23 (only partially shown) and are connected to a feed section 24 and an extraction section 25.

[0073] A first group (lower in the drawing) of U-shaped bends 23 are arranged side by side in the first region 11, and a second group (upper in the drawing) of U-shaped bends 23 are arranged side by side in the second region 12. The U-shaped bends 23 of the second group are formed in the connecting element 30, and the pipe portion 21 extends from the connecting element 30 in the second region 12 to the first region 11.

[0074] Within the scope of the present invention, the use of connection elements 30 is optional but advantageous, whereas the embodiments of the present invention described below relate in particular to embodiments of means for power input in the first area 11. This is carried out by using power input elements 41, which are illustrated here in a very simplified manner, only one of which is shown.

[0075] 4A and 4B, the power input element 41 protrudes into the connecting chamber 60. The power input element 41, more precisely its rod-shaped portion, is accommodated in a longitudinally movable manner in a corresponding wall passage in the wall separating the reaction vessel 10 and the connecting chamber 60, so that no gas-tight closure is provided here. As indicated by arrow I (hence only one arrow is shown), an inert gas is provided and fed into the connecting chamber 60 and enters the reaction vessel 10 via the wall passage. Inside the reaction vessel, the power supply element 41 is accommodated in a longitudinally movable manner. For providing and feeding the inert gas, suitable gas supply means are provided, indicated here as 80, which is very simplified and comprises, for example, one or more gas tanks and corresponding lines 81.

[0076] FIG. 3 shows a schematic diagram of a reactor for carrying out chemical reactions, generally designated 200, in accordance with an embodiment of the present invention.

[0077] In reactor 200, the tube sections, here by contrast designated 22, comprise in each case tube sections 22 consisting of several reaction tubes 20, which are arranged side by side in a fluidly disconnected manner in the reaction vessel 10 and which are in each case connected to a feed section 24 and an extraction section 25. For the remaining elements, explicit reference is made to the above explanations relating to the previous figures.

[0078] Again, the use of a connection element 30 within the scope of the present invention is optional but advantageous. Here again, the power input element 41 and the connection chamber 60 are illustrated in a very simplified manner. The supply of inert gas I here takes place substantially as described above. The power input element can have a sleeve-like region 49, which is arranged in the first region 11 around the reactor tube 20 or tube section.

[0079] 4A and 4B show partial views of a reactor 100 with a connecting chamber 60 according to an embodiment of the invention in a longitudinal section (FIG. 4A) and in a cross section (FIG. 4B) in which only selected elements are illustrated. In each case, FIGS. 4A and 4B are particularly greatly simplified insofar as a practical reactor can provide a significantly larger number of elements illustrated herein.

[0080] As can be seen particularly in FIG. 4A , each rod-shaped portion 43 of the power input element extends through the wall 14 of the reaction vessel 10 into the wall passage 15. As previously mentioned, each rod-shaped portion 43 is housed in a longitudinally movable manner, and no airtight closure is present in the wall passage 15. The connecting chamber 60 from which the rod-shaped portion 43 protrudes is located outside the reaction vessel 10, adjacent to the wall 14 of the reaction vessel 10, and into the wall passage 15, the rod-shaped portion 43 extends through the reaction vessel wall. Because no airtight closure is formed in the wall passage 15, inert gas supplied to the connecting chamber through a suitable opening 82 or nozzle, as illustrated by arrow I1, can flow into the reaction vessel, as illustrated by arrow I2. Inert gas can also be supplied laterally to the connecting chamber 60, as illustrated by arrow I3 in FIG. 4B.

[0081] Cooling panels 61 are provided within the connection chamber 60 and can be arranged as is particularly evident in Figure 4B. A cooling fluid can flow through the cooling panels, which can be arranged between at least two or at least two groups of the rod-like portions 43 that protrude into the connection chamber 60.

[0082] The connecting chamber 60 in each case has side walls 62 extending perpendicular to the wall 14 of the reaction vessel 10, the rod-shaped portion 43 extending through the wall of the reaction vessel, and as can be seen in Figure 4B and not shown separately in Figure 4A, one or more further cooling panels 63 can also be arranged on at least one of the side walls 62.

[0083] 4A, the connecting chamber 60 has a bottom wall 64 extending parallel to the wall 14 of the reaction vessel 10, through which the rod-shaped portion 43 extends, the bottom wall 64 being formed in at least one portion as a hollow wall, also configured to allow a cooling fluid to flow therethrough. The connecting chamber 60 is designed without a device for providing forced convection in the gas atmosphere 65 surrounding the cooling panel 61 and the rod-shaped portion 43.

[0084] In the connection chamber 60, a flexible connection element, illustrated as a strand 66 in FIG. 4A, is connected to the rod-shaped portion 43 and, with its end not connected to the rod-shaped portion 43, is fixed to a rigid contact element 67, which is arranged so that it cannot move within the connection chamber 60 and here is fixed at its bottom 64 to an insulating and airtight receptacle (not specified in more detail).

[0085] Figure 5 illustrates schematically a reactor for carrying out chemical reactions according to a further embodiment of the present invention, extending the previous diagrammatic illustration, in which elements already illustrated above in Figure 2 are partially not illustrated again. All these elements may be part of the reactor illustrated in Figure 5. In Figure 5, in particular, the reaction vessel 10 and the connecting chamber 60 are illustrated in a greatly simplified manner.

[0086] As illustrated here, the reactor vessel 10 is connected to a chimney 70 via a target outlet 71, the chimney having suitable insulation 72 in the area adjacent to the reactor vessel 10. The chimney 70 may have a height h of, for example, 20 to 50 meters above ground level, in order to enable hydrocarbon leakage to be dissipated to a safe location in the event of an accident. A so-called velocity seal 74 is also provided, as well as one or more sensors for detecting the oxygen and / or hydrocarbon content in the stack gases. Optionally, an ignition device or pilot burner 73 may additionally be installed in the area of ​​the stack outlet to at least partially prevent unburned hydrocarbons from escaping into the atmosphere in the event of a disaster.

[0087] FIG. 6 shows, in diagram form, a schematic representation of the principle of chimney sizing according to an embodiment of the present invention, in which the oxygen content in percent is plotted on the horizontal axis and the rate of volume increase associated with the reaction is plotted on the m 3 / s are plotted on the vertical axis. Graph 601 illustrates the relationship already explained with reference to the table. Dashed line 602 shows the value required for a maximum pressure rise of 20 mbar for a chimney diameter of 500 mm, and dashed line 603 shows the corresponding value for a chimney diameter of 900 mm.

Claims

1. A reactor (100, 200) for carrying out a chemical reaction, comprising a reaction vessel (10) and one or more reaction tubes (20), wherein one or more power input elements (41) are introduced into the reaction vessel (10) for the electrical heating of the one or more reaction tubes (20), and the reactor (100, 200) comprises: - the one or more power input elements (41) each have a rod-shaped portion (43) for the electrical heating of the one or more reaction tubes (20), the one or more rod-shaped portions (43) each extending through the wall (14) of the reaction vessel (10) in respective wall passages (15); - a connecting chamber (60) from which said rod-shaped portion (43) projects is arranged outside said reaction vessel (10) adjacent to said wall (14) of said reaction vessel (10) in which said wall passage (15) is formed; - gas supply means (80-82) are provided which are arranged to add an inert gas to said connection chamber (60); the wall passage (15) inside which the rod-shaped portion (43) is accommodated in a longitudinally displaceable manner is designed to be gas permeable so that at least a part of the inert gas supplied into the connecting chamber (60) flows into the reaction vessel (10); a reactor (100, 200) characterized in that each of the tube sections (21, 22) of the one or more reaction tubes (20) extends between a first region (11) and a second region (12) in the reaction vessel (10), the tube sections (21, 22) in the first region (11) are each electrically connected to power connections (U, V, W) of a power source (50) for electrical heating of the tube sections (21, 22), and a power input arrangement (40) is provided in the first region (11) to which each one or each group of the tube sections (21, 22) is electrically connected, the power input arrangement (40) each comprising one of the power input elements (41) having the rod-shaped portion (43) extending through a wall (14) of the reaction vessel (10) into a wall passage (15).

2. 2. The reactor (100, 200) according to claim 1, wherein the gas supply means (80-82) are configured to provide, as the inert gas, a gas or gas mixture having a superatmospheric pressure content of nitrogen, carbon dioxide, and / or argon, respectively.

3. 3. The reactor (100, 200) according to claim 1 or claim 2, wherein the reaction vessel (10) and the connecting chamber (60) are housed together in an airtight manner, except for one or more target outlets (71) for gas leakage.

4. 4. The reactor (100, 200) of claim 3, wherein the one or more target outlets (71) are connected to one or more chimneys (70).

5. The reactor (100, 200) according to claim 4, wherein the gas supply means (80-82) are set to adjust the maximum oxygen content in the reaction vessel (10) and / or the connecting chamber (60) based on the dimensioning of the chimney (70).

6. 6. The reactor (100, 200) of claim 5, wherein the gas supply means (80-82) is configured to regulate the amount of inert gas based on oxygen measurements in the one or more chimneys (70).

7. 7. The reactor (100, 200) of claim 6, further comprising means configured to prevent operation of the reactor (100, 200) by addition of hydrocarbons to the reactor tubes if the measured oxygen content exceeds a target oxygen content.

8. 8. The reactor (100, 200) according to any one of claims 4 to 7, comprising means configured to prevent operation of the reactor (100, 200) by addition of hydrocarbons to the reaction tubes if the pressure in the reaction vessel (10) and / or the hydrocarbon content in the chimney (70) exceeds a predetermined value.

9. 9. The reactor (100, 200) according to any one of claims 1 to 8, wherein cooling panels (61) through which a cooling fluid can flow are provided in the connecting chamber (60) and are arranged between at least two or at least two groups of the rod-shaped portions (43) protruding into the connecting chamber (60).

10. A method for carrying out a chemical reaction using a reactor (100, 200) having a reaction vessel (10) and one or more reaction tubes (20), wherein one or more power input elements (41) are introduced into the reaction vessel (10) for the electrical heating of the one or more reaction tubes (20), the method comprising the use of a reactor (100, 200), in which: - the one or more power input elements (41) each have a rod-shaped portion (43) for the electrical heating of the one or more reaction tubes (20), the one or more rod-shaped portions (43) each extending through the wall (14) of the reaction vessel (10) into a respective wall passage (15); - a connecting chamber (60) from which said rod-shaped portion (43) projects is arranged outside said reaction vessel (10) adjacent to said wall (14) of said reaction vessel (10) in which said wall passage (15) is formed; - gas supply means (80-82) are provided which are arranged to add an inert gas to said connection chamber (60); the wall passage (15) inside which the rod-shaped portion (43) is accommodated in a longitudinally displaceable manner is designed to be gas permeable so that at least a part of the inert gas supplied into the connecting chamber (60) flows into the reaction vessel (10); a reactor is used in which each tube section (21, 22) of the one or more reaction tubes (20) extends between a first zone (11) and a second zone (12) in the reaction vessel (10), the tube sections (21, 22) in the first zone (11) are each electrically connected to a power connection (U, V, W) of a power source (50) for heating the tube sections (21, 22), and a power input arrangement (40) is provided in the first zone (11) to which each one or each group of the tube sections (21, 22) is electrically connected, the power input arrangement (40) each comprising one of the power input elements (41) having the rod-shaped portion (43) extending through a wall (14) of the reaction vessel (10) into a wall passage (15).

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