Reactor and method for carrying out chemical reactions

Abstract

The invention relates to a reactor (100, 200) for carrying out chemical reactions, having a reactor vessel (10), one or more reaction tubes (20) and means (40) for electrically heating the one or more reaction tubes (20). The reactor vessel (10) has one or more discharge openings (61, 62) which are permanently open or are arranged to open at a higher than preset pressure level, and a gas feed device (50) is provided which is arranged to feed inert gas into the interior of the reactor vessel (10). A corresponding method is also the subject of the invention.

Description

Technical Field

[0001] This invention relates to reactors and methods for carrying out chemical reactions. Background Technology

[0002] In many processes in the chemical industry, reactors are used, in which one or more reactants pass through heated reaction tubes and undergo a catalytic or non-catalytic reaction. Specifically, heating is used to overcome the activation energy required for the chemical reaction to occur. The reaction can proceed entirely endothermally or exothermally after the activation energy has been overcome. This invention particularly relates to strongly endothermic reactions.

[0003] Examples of these processes include steam cracking, various reforming processes, particularly steam reforming, dry reforming (carbon dioxide reforming), mixed reforming processes, and alkane dehydrogenation processes. In steam cracking, the reaction tubes are guided through the reactor in the form of coils, which have at least one U-bend within the reactor, while in steam reforming, tubes without U-bends are typically used to pass through the reactor.

[0004] This invention applies to the processes and designs of all such reaction tubes. Articles in Ullmann's *Encyclopedia of Industrial Chemistry*, "Ethylene," "Gas production," and "Propene," such as DOI:10.1002 / 14356007.a10_045.pub2 (April 15, 2009), DOI:10.1002 / 14356007.a12_169.pub2 (December 15, 2006), and DOI:10.1002 / 14356007.a22_211 (June 15, 2000), are cited herein for illustrative purposes only.

[0005] The reaction tubes of the corresponding reactor are typically heated by a burner. In this case, the reaction tubes pass through the combustion chamber, and the burner is also located within the combustion chamber.

[0006] However, as described in DE102015004121A1 (similar to EP3075704A1), the demand for syngas and hydrogen produced, for example, is increasing, even with or without reduction in local CO2 emissions. However, processes using combustion reactors cannot meet this demand due to the combustion of typical fossil fuel carriers. Other processes are excluded, for example, due to high costs. The same applies to the production of olefins and / or other hydrocarbons via steam cracking or alkane dehydrogenation. In such cases, processes with at least minimal on-site CO2 emissions are also required.

[0007] Against this backdrop, the aforementioned DE102015004121A1 proposes electrically heating the reactor used for steam reforming in addition to combustion. In this case, one or more voltage sources are used to provide a three-phase AC voltage across three external conductors. Each external conductor is connected to the reaction tube. A star circuit is formed, wherein the star point is realized by a collector, to which pipes lead and to which the reaction tube is electrically connected. Thus, the collector is ideally kept at no potential. In the vertical direction, the collector is arranged below and outside the combustion chamber and preferably transverse to the reactor tube or extends horizontally. WO2015 / 197181A1 also discloses a reactor in which the reaction tube is arranged in a star circuit.

[0008] Besides direct heating of the reaction tube (current flowing through the reaction tube), there are various concepts for indirect electric heating of the reaction tube. Among these, indirect electric heating can be performed in the form of external electric heating, as described in WO2020 / 002326A1. Internal heating is also possible, for example, as disclosed in WO2019 / 228798A1. In addition to resistance or impedance heating, induction electric heating of the reaction tube or catalyst bed can be performed, for example, as described in WO2017 / 072057A1. For example, induction heating can heat internal or external heating elements or the reaction tube itself. Direct (non-induction) heating of the reaction tube is also disclosed in DE102015004121A1. For heating, the basic concept of using multiphase or single-phase alternating current or direct current can be implemented. In the case of directly heating the reactor with direct current or single-phase alternating current, a star circuit without potential points cannot be realized, but the power input can be implemented in a manner similar to that in the case of multiphase direct current. This invention applies to all variations of electric heating.

[0009] WO 2004 / 091773A1 describes an electrically heated reactor for carrying out gas reactions at high temperatures. The reactor includes a reactor block, one or more integral modules of material suitable for electric heating enclosed by a shell, channels passing through the modules and designed as reaction passages, and means for conducting or inducing current within the reactor block. Safety is enhanced during operation of such a reactor because the shell of the reactor block has a double-walled sheath that hermetically seals the reactor block, and at least one means for feeding inert gas into the double-walled sheath.

[0010] As explained below, in the case of electrically heated reactors, special aspects related to safety must be considered. The object of the present invention is to illustrate measures that take these aspects into account, and in this way allow for the advantageous operation of electrically heated reactors. Summary of the Invention

[0011] In light of this background, the present invention proposes a reactor and method for carrying out chemical reactions.

[0012] In the electric furnace concept upon which this invention is based (the term "furnace" is generally understood to refer to the corresponding reactor or at least its insulated reaction space), for example, the reaction tube or its corresponding tube segment (hereinafter also simply referred to as "tube") itself serves as a resistor to generate heat. This direct method has higher efficiency and a higher achievable heat flux density compared to indirect heating via external electric heating elements. However, as mentioned at the beginning, any other type of electric heating (direct or indirect, in the form of resistance, impedance, or induction heating, via single-phase or multi-phase alternating current or direct current) can also be carried out within the framework of this invention, if said heating proves advantageous.

[0013] In the case of multiphase alternating current heating, electricity is fed directly into the heated reaction tubes via M individually connected phases. The conductive reaction tubes connected to the M phases can also be electrically connected to a star point at the other end. The number of phases M is particularly 3, corresponding to the number of phases in a conventional three-phase current source or network. However, in principle, the invention is not limited to the use of three phases and more phases can be used, for example, 4, 5, 6, 7, or 8 phases. The phase offset is particularly 360° / M, i.e., 120° in the case of three-phase alternating current.

[0014] In multiphase alternating current electric heating, potential equalization between phases is achieved at the star point via a star circuit, which ideally renders electrical insulation of the connected pipes redundant. This represents a particular advantage of this furnace concept, as rupture of the metal reaction tubes used to insulate specific sections is undesirable, especially given the high temperatures used and the resulting high material and structural costs.

[0015] However, the measures proposed according to the invention and explained below are applicable in the same manner to the use of single-phase alternating current (AC) and direct current (DC), and the invention can be used in reactors heated by AC and reactors heated by DC, or in corresponding hybrid forms. As mentioned above, the invention is also applicable to indirectly heated reaction tubes. For example, in a DC arrangement, only the type of current source and the corresponding reaction tube region or energized section opposite the power input differ from the AC arrangement. In the latter, electrical connections between different tube sections are performed only optionally. Since there are no potential-free points in a DC arrangement, suitable current discharge elements should be provided that safely guide the current back to the outside. The latter can be designed similarly to the power input described below.

[0016] This invention relates to the protection of electrically heated reactors of the type described above, which is particularly necessary in the event of damage to the reaction tubes (“coil tear”). In the event of such damage, one or more reaction tubes can be completely shut off; however, the invention is also advantageous for minor leaks. In the event of such damage, combustible gases may escape suddenly or slowly into the reactor vessel, which is substantially sealed due to insulation.

[0017] Compared to the purely electrically heated reactor used according to the invention, this damage is a lower level of safety concern in conventional combustion reactors because the combustible gas generated from the reaction tube in the form of a hydrocarbon-vapor mixture reacts immediately and continuously through combustion occurring in the reactor vessel or corresponding combustion chamber, or because the oxygen content is significantly reduced due to the combustion and the gas space around the reaction tube is thus essentially "inertized." Conversely, in the case of purely electrically heated reactors, the corresponding combustible gas can accumulate in the reactor vessel, and there, at normal oxygen content in the air and temperatures above the auto-ignition temperature, for example, reaching the explosion or deflagration limit. In the absence of explosion or deflagration, complete or incomplete combustion also results in energy input and can therefore lead to overheating. Complete or incomplete combustion itself can also lead to a significant pressure increase, along with the volume of gas flowing out of the reaction tube. The present invention reduces this pressure increase because combustion of the gas mixture is prevented.

[0018] In the terminology of the claims, the present invention relates to a reactor for carrying out a chemical reaction, comprising a reactor vessel (i.e., an insulated or at least partially insulated region), one or more reaction tubes, and means for electrically heating the one or more reaction tubes. The reactor according to the invention is specifically configured to carry out the chemical reaction at a temperature level for high-temperature reactions as explained below. The reaction tubes are guided through the reactor with at least one U-bend, or without a U-bend. The electrically heating means can be designed as explained in detail above. On one hand, the means can be for feeding electricity to one or more reaction tubes, meaning generating current flow and corresponding heating in one or more reaction tubes, for example, a rigid current bar guided into the reactor; but the means can also be for indirect heating, such as resistance and / or induction heating devices that conduct heat and / or transfer heat to one or more reaction tubes conductively and / or by thermal radiation, or generate eddy currents, for example, in one or more reaction tubes or a catalyst bed, and generate heating in this way.

[0019] Within the framework of this invention, the reactor vessel has one or more discharge ports that are permanently open or configured to open under conditions above a preset pressure level, and provides a gas feed device configured to feed inert gas into the interior of the reactor vessel.

[0020] The following mainly describes the reactor designed according to the present invention or different embodiments thereof. The corresponding explanations also apply to the corresponding methods, and the correspondingly configured apparatus performs the specified method steps respectively.

[0021] For feeding inert gas, the gas feeding device includes, for example, a feed nozzle or opening, which, together with a pipeline and a connected gas reservoir, leads into the reactor vessel, thereby allowing the inert gas to be fed into the interior of the reactor. Specifically, the reactor vessel is a chamber significantly (i.e., at least 90, 95, or 99%) surrounded by insulated walls. The interior of the reactor vessel is the area where the reaction tubes are arranged and is surrounded by the reactor walls. For example, it can also be a double-walled design where the reactor walls are not part of the interior.

[0022] In all embodiments of the invention, the inert gas may be a gas or gas mixture having a super-atmospheric content of nitrogen, carbon dioxide, and / or argon, or a gas feed device may be provided to supply the corresponding inert gas, for example, by keeping the corresponding inert gas available, or by mixing pure gas or incorporating pure gas into air. In particular, the non-flammable gas content may exceed 50%, 60%, 70%, 80%, or 90%. Therefore, the inert gas is not necessarily a purely "inert gas" in the conventional sense; rather, it is sufficient if the inert gas—particularly due to its non-flammable gas content—at least partially reduces the flammability of the mixture, i.e., reduces the risk of ignition, explosion, or deflagration. The inert gas used within the framework of this invention may particularly have a sub-atmospheric oxygen content—for example, an oxygen content of less than 10%, 5%, 1%, 0.5%, or 0.1%. The inert gas may also be particularly (completely or substantially) oxygen-free.

[0023] By means of the proposed measures, the present invention provides a containment with a conditioned atmosphere for thermal insulation and safety-related protection for high-temperature reactors, wherein energy input is electrically provided. Within the framework of the invention, fully electric heating can be particularly provided, i.e., heating of the reaction tubes, at least within the reactor vessel, advantageously primarily or entirely by thermal heating, i.e., at least 90, 95, or 99% of the heat introduced herein, particularly all the heat introduced herein, is carried out by an electric heating device. The heat input of the gas mixture conducted through one or more reaction tubes is not considered here; therefore, this proportion is particularly related to the heat transferred from the outside to the walls of one or more reaction tubes within the reactor vessel or the heat generated within the walls of the reactor vessel or the catalyst bed.

[0024] Therefore, in its most general form, the present invention describes a containment for an electrically heated high-temperature reactor with feed hydrocarbons (wherein the term "high-temperature reaction" specifically refers to a reaction carried out at temperatures exceeding 500°C, particularly at temperatures between 700°C and 1000°C), the containment: 1. provides an inert atmosphere around the tubes, and 2. is not permanently sealed. Applications of electrically heated reactors with process gas temperatures close to or above the auto-ignition temperature of the hydrocarbons contained in the process gas are particularly preferred. The term "process gas" refers to a gas or gas mixture flowing through one or more reaction tubes.

[0025] Embodiments of the invention differ particularly in that they contain one or more drain ports that are permanently open or configured to open under conditions above a preset pressure level. However, combinations of drain ports of a corresponding design are also possible in principle.

[0026] In the following set of embodiments, referred to as “Group 1”, one or more discharge orifices are permanently open. This means that the one or more discharge orifices do not provide any mechanical resistance to prevent fluid from flowing into or out of the reactor vessel, except for possible narrowing of the flow cross-section. Therefore, the one or more openings are not closed.

[0027] Conversely, in the set of embodiments referred to below as the "second group," one or more vent holes are configured to open under conditions above a predetermined pressure level. These one or more vent holes close under conditions below a predetermined pressure level, or are configured to temporarily or permanently open upon reaching the predetermined pressure level. In this regard, the term "permanently" open specifically refers to an irreversible opening, such that in this embodiment, re-closing by venting gas will not occur after the pressure subsequently falls below the predetermined pressure level. In contrast, the term "temporarily" open refers to an opening that results in re-closing.

[0028] To open at a preset pressure level, one or more vent holes may have, for example, one or more spring-loaded or weight-loaded caps with opening resistance defined by the spring or load characteristics, thus opening only at the corresponding pressure. In one embodiment of the second set of embodiments, one or more rupture discs or pressure-reducing valves may also be used in a manner known per se. Pressure values ​​may also be detected, for example, by a sensor, and any type of opening mechanism, such as an ignition mechanism or an electrically actuated actuator, may be triggered when a preset threshold is exceeded. This makes it possible to release a sufficiently large cross-section within a short response time if necessary, which remains closed during normal operation in the manner described.

[0029] Specifically, in the first set of embodiments, but also possibly in the second set of embodiments, the reactor may be configured to undergo continuous purging using inert gas. In other words, the gas feeding device is configured to continuously feed inert gas into the reactor vessel. In the first set of embodiments, the inert gas may flow primarily through one or more permanently open vent holes, but optionally also through additional vent holes (particularly unavoidable or intentionally created gas leaks or bypasses), such as to an existing flue. In the second set of embodiments, wherein the one or more permanently open vent holes are generally closed, and additional openings for inert gas outflow (e.g., bypass pipes to the flue) are either provided or unavoidably present, for example, due to leaks in the reactor vessel.

[0030] However, as an alternative to continuous purging, inert gas can be supplied to the reactor only once or periodically according to one or more predetermined criteria. A gas feed device is then provided for such operation. One or more predetermined criteria may include, for example, reaching a preset pressure value and / or a preset concentration, such as a minimum and tolerable oxygen content. However, a criterion may also be the initial commissioning of the reactor vessel. In particular, continuous measurements can be taken, and inert gas feeding can begin whenever a corresponding measured value indicates that a preset criterion is no longer met. Especially in the second set of embodiments, a one-time or periodic supply of inert gas can be provided at a pressure value lower than that used to open one or more vent holes, as this prevents free escape of the inert gas and allows it to remain in the reactor vessel for a longer period.

[0031] In a particularly preferred embodiment of the first set of embodiments, the reactor is configured to operate the reactor vessel at a pressure level below atmospheric pressure. In this case, means for forming a gas flow exiting the reactor is provided. In this regard, one or more exhaust ports (which are permanently open in this set of embodiments) can be permanently connected to a flue with a sufficiently high flue opening. This results in a static negative pressure in the reactor vessel due to the high temperature within the reactor vessel and the resulting lower density of the contained gas volume. In this regard, the use of a blower may also be provided, for example, until the corresponding static negative pressure is formed.

[0032] Conversely, in a particularly preferred embodiment of the second set of embodiments, the reactor is configured to operate the reactor vessel at a pressure level exceeding atmospheric pressure. This can be achieved, in particular, by feeding an inert gas to a pressure level above atmospheric pressure, which is below the opening pressure of the exhaust port.

[0033] According to the system of the first set of embodiments, it has been inertized to a certain extent and "open" to the environment (especially due to the slight negative pressure in the reactor vessel due to the flue effect), or according to the "openable" system of the second set of embodiments of the invention (especially operable when there is a certain overpressure in the reactor vessel), it can limit the rate of pressure increase to a tolerable level that meets the design limitations of the reactor vessel in the event that hydrocarbons escape and damage the reaction tubes.

[0034] Due to the concept of a reactor vessel supplied with inert gas, the oxygen content present there can be reduced. The reaction rate of hydrocarbons escaping in the event of damage and the resulting significant additional volume increase (as a result of the heat input of the reaction) are proportional, under first-order approximation, to the partial pressure of oxygen or molar oxygen content in the vessel.

[0035] In both embodiments of the invention, due to the inert gas feed, the reactor vessel walls advantageously do not need to be designed to be completely airtight (which would only be possible with very high material expenditures, such as the use of heat-resistant bellows structures), because of the high temperatures generated at certain locations due to the required movement possibilities. When operating at sub-atmospheric pressure levels with the flue, although air may be drawn into the reactor vessel through corresponding leaks, this air is correspondingly discharged and diluted by the continuous flow brought in by the flue. In this way, safety issues can be prevented when using inert gases or their components that may potentially impair breathing. Conversely, in the case of operation at extra-atmospheric pressure levels, air inflow into the reactor vessel can be reliably prevented due to uniform pressure propagation. Inert gas escaping through leaks can be discharged or diluted, for example, through adequate ventilation outside the reactor vessel.

[0036] Because the concept of a reactor vessel supplied with an inert gas is proposed, the oxygen content can be reduced here. As can be used according to the invention, the reaction rate of escaping hydrocarbons, and therefore the significant additional volume increase rate (as a result of the heat input of the reaction), is related to the oxygen partial pressure or oxygen mole fraction under a first-order approximation. This correlation is summarized in Table 1 below, where xO2 represents the molar oxygen content, V reak This indicates the rate of volume increase associated with the reaction.

[0037] Therefore, it is advantageous to configure the gas feed device to adjust the maximum oxygen content in the reaction vessel according to the size of the flue or multiple flues. Table 1

[0038] Maximum permissible pressure p max Depending on the mechanical stability of the individual chambers or the surrounding containment, this pressure must be at least equal to the pressure p in the event of a coil rupture or other corresponding safety-related event. box The same size, which in turn depends on the volume V of the relevant chamber. Box flue diameter D Chimney And molar oxygen content: p max ≥p box =f(V Box D Chimney (xO2)

[0039] This requirement led to the design basis for flue dimensions, namely, the permanent or temporary connection to the environment through one or more exhaust vents, and vice versa. See below for reference. Figure 9 This relationship is explained again. For example, if a maximum permissible pressure increase of 20 mbar is used here as a basis, as shown by dashed lines 601 and 602, so that a flue with a diameter of 500 mm (dashed line 601) can be used, a reaction-related volume increase rate of up to about 10 cubic meters per second can be generated, which results in a maximum oxygen content of about 1%, which is adjusted by inertization.

[0040] Conversely, if inerting to a maximum oxygen content of 1% is desired, a flue with a diameter of at least 500 mm must be used. To enable the use of a flue with a diameter of 900 mm (dashed line 602), a volume increase rate of only about 42 cubic meters per second can be achieved, resulting in a maximum oxygen content of about 4%, which is regulated by inerting. Similarly, as explained above, if inerting to a maximum oxygen content of 4% is desired, then a flue diameter of at least 900 mm must be used here.

[0041] The lower the oxygen content inside the reactor vessel, the smaller the volume increase. Therefore, the diameter of the emergency flue that must discharge the additional volume can also be smaller. For effectively limiting oxygen content, it is important to always maintain a sufficiently good seal to the environment to prevent the ingress of oxygen-containing spurious air as much as possible. However, as explained, a complete seal is not necessary.

[0042] In other words, within the framework of this invention, the maximum oxygen content in the reaction vessel is adjusted using an inert gas. This maximum oxygen content, in the first set of embodiments, is selected based on the size of one or more flues in the presence of a flue, or a gas feeder is provided for feeding inert gas or adjusting the oxygen content accordingly. The gas feeder can also be specifically configured to feed inert gas at a pressure not exceeding a target pressure. In the second set of embodiments, feeding can also be based on oxygen concentration or target pressure and flue size.

[0043] The amount of inert gas fed can be regulated by a corresponding control device, particularly based on oxygen measurements in the reactor vessel or flue (if present), which, if present, results in a constant oxygen content during operation. The corresponding safety concept according to the invention includes halting or continuing to halt reactor operation when the measured oxygen content exceeds a target oxygen content. For example, the feed of hydrocarbons into the reaction tube and / or its heating can only be released when the required oxygen content is insufficient. When a fault is detected, reaction operations involving the addition of hydrocarbons to the reaction tube can generally be prevented.

[0044] For example, a pressure sensor can be used to detect unacceptable gas escape from the reaction tube. When gas escape is detected, the feed of hydrocarbons into the reaction tube can be prevented, thereby minimizing the total amount of escaped hydrocarbons.

[0045] To detect very minor damage (leakage flow without a sudden increase in pressure), the hydrocarbon content in the reactor vessel or flue can also be continuously measured, if present (e.g., in the form of carbon monoxide equivalent). An unacceptable value can also lead to a halt in the hydrocarbon feed.

[0046] Therefore, the present invention includes, more generally, determining a value characterizing gas escape from one or more reaction tubes based on pressure and / or hydrocarbon measurements, and activating one or more safety measures if the value exceeds a preset threshold.

[0047] According to the method for carrying out a chemical reaction proposed in this invention, a reactor is used, comprising a reactor vessel, one or more reaction tubes, and a device for electrically heating the one or more reaction tubes. According to the invention, the reactor vessel used is a reactor vessel having one or more exhaust ports, which are permanently open or configured to be open under conditions above a preset pressure level, and according to the invention, inert gas is fed into the interior of the reactor vessel using a gas feeding device.

[0048] For further features and advantages of the corresponding methods in which a reactor of one of the configurations of the invention explained above is used advantageously, refer to the above explanation. Attached Figure Description

[0049] The present invention will now be further described with reference to the accompanying drawings, wherein the configuration of the present invention is described by referring to and comparing with the prior art.

[0050] Figure 1 The diagram schematically illustrates a reactor for carrying out a chemical reaction, not configured according to the invention.

[0051] Figures 2 to 8 A reactor for carrying out a chemical reaction according to an embodiment of the present invention is illustrated schematically.

[0052] Figure 9 The dimensions of the flue are schematically illustrated according to an embodiment of the present invention. Detailed Implementation

[0053] In the figures below, functionally or structurally corresponding elements are indicated by the same reference numerals and are not repeated for clarity. If the components of the device are explained below, the corresponding explanations will also relate to the methods performed thereon, and vice versa. The description of the figures repeatedly refers to alternating current heating. However, as previously stated, the invention is also applicable in the same manner to the use of direct current heating. Refer here to the explanation above.

[0054] Figure 1 The diagram schematically illustrates a reactor for performing a chemical reaction, not configured according to the invention.

[0055] The reactor designated 300 here is designed for carrying out chemical reactions. Specifically, for this purpose, it has an insulated reactor vessel 10 and reaction tubes 20, wherein numerous sections of the reaction tubes 20 (represented here by 21 for two examples only) extend between a first region 11' and a second region 12' within the reactor vessel 10. Reference will be made below. Figure 2The reaction tube 20, described in more detail, is connected to the top or supporting structure of the reactor vessel via a suitable suspension 13. In the lower region, the reactor vessel may, in particular, have a furnace (not shown). It goes without saying that multiple reaction tubes may be provided here and in each subsequent case.

[0056] Figure 2 A reactor for carrying out a chemical reaction according to an embodiment of the present invention is schematically shown, generally indicated by 100.

[0057] The regions previously indicated by 11' and 12' are in the form of regions 11 and 12, wherein the tube segments 21 used for heating tube segments 21 in the first region 11 can be electrically connected to the connecting terminals U, V, and W of the multiphase AC power supply 41 via connecting elements 42, respectively, resulting in a device for electrically heating the reaction tube 20, indicated integrally by 40. Switches, etc., and specific connection types are not shown. In the embodiment of the invention shown here, the tube segments 21 are electrically interconnected in the second region 12 via connecting elements 30, which are integrally connected to one or more reaction tubes 20 and arranged within the reactor vessel 10. A neutral conductor may also be connected to the connecting element 30.

[0058] In the example shown here, a star circuit with multiple AC phases is thus implemented. However, as mentioned many times, the present invention can also be provided using single-phase AC heating, DC heating, or other heating means, such as induction or indirect heating in the sense described above.

[0059] In the reactor 100 shown here, multiple segments 21 of a reaction tube 20 (although multiple such reaction tubes 20 may be provided) are thus arranged side by side in the reactor vessel 10. The segments 21 enter each other through a U-shaped bend 23 (shown only partially) and are connected to the feed section 24 and the extraction section 25.

[0060] A first set of U-shaped bends 23 (at the bottom of the figure) are arranged side-by-side in the first region 11, and a second set of U-shaped bends 23 (at the top of the figure) are arranged side-by-side in the second region 12. The second set of U-shaped bends 23 are formed in the connecting element 30, and the pipe segment 21 extends from the connecting element 30 in the second region 12 to the first region 11. The power input element 52 can be designed as needed, for example, rigid, and has rod-shaped segments that can pass through the wall of the reactor vessel 10.

[0061] The apparatus for feeding inert gas into the reactor vessel is generally indicated by 50. As shown by arrow 53 (shown only partially accordingly), the inert gas is fed into the reactor vessel 10 specifically through wall openings, nozzles, etc., in one or more walls of the reactor vessel 10. To provide and feed the inert gas, a suitable gas feeding device is provided, which is also shown in a highly simplified manner here, including, for example, one or more gas tanks 51 and corresponding pipelines 52.

[0062] Figure 3 A reactor for carrying out a chemical reaction according to the configuration of the invention is schematically shown, generally indicated by 200.

[0063] In reactor 200, the pipe sections—referred to here as 22 for comparison—each comprise a section 22 consisting of multiple reaction tubes 20, wherein the pipe sections 22 are arranged side-by-side in a non-fluidly connected manner within reactor vessel 10, and are respectively connected to feed section 24 and extraction section 25. For the remaining elements, please refer specifically to the explanations related to the above figure.

[0064] Conversely, the use of connecting element 30 within the framework of this invention is optional, although it is particularly advantageous when using a multiphase AC heater. Current input element 42 is also shown here in a highly simplified manner. Inert gas is fed here according to arrow 53, as generally explained above. Current input element 42 may have a sleeve-shaped region 43 to which it is attached and positioned within the first region 11 surrounding the reaction tube 20 or tube segment.

[0065] Figures 4 to 8 A partial view of the reactor according to an embodiment of the present invention is shown in a further simplified illustration, wherein the flue 60 is shown. The gas feed device 50 for feeding inert gas and the device 40 for electric heating are not shown. The reaction tube 20 is as follows... Figure 2 The diagram shows a U-shaped bend, but it can also be designed in any other form, such as... Figure 3 As shown. The inert gas feed is indicated by arrow 53 at only one location.

[0066] like Figure 4 As indicated by arrow 54, leaked air can enter reactor vessel 10 through one or more leaked air inlets. In the embodiment shown here, reactor vessel 10 has a permanently open exhaust port 61 connected to flue 60. The inert gas feed and the high temperature associated with the end 63 of flue 60 within reactor vessel 10 cause the flow indicated by arrow 64. Within the reactor vessel, the high temperature results in a static pressure p Box When the inert gas feed is carried out in a proper manner, the static pressure p Box atmospheric pressure p below the surrounding environment AtmIn other words, the amount of purge gas should not be too large. If the amount of purge gas is very large, the pressure loss in the flue 60 will cause the internal pressure in the reactor vessel 10 to approach or even exceed the external pressure.

[0067] In this embodiment, where the reactor vessel is under negative pressure, this prevents ambient air from flowing back into the reactor vessel 10; any low-leakage air ingress due to insufficient sealing is also compensated for. Specifically, the inert gas feed into the reactor vessel 10 can be regulated by oxygen measurement 65 in the flue 60, thereby maintaining a constant oxygen content during operation.

[0068] According to Figure 4 Comparison of embodiments, based on Figure 5 The reactor vessel 10 operates at a pressure level exceeding atmospheric pressure, wherein an inert gas is continuously fed into the reactor vessel 10. The reactor vessel 10 has, for example, a vent 62 in the form of a rupture disc, which is configured to open under conditions exceeding a preset pressure level.

[0069] In this alternative embodiment with pressurized operation, the inert gas feed compensates for low gas leakage into the atmosphere, indicated here by arrow 55. In this case, the purging rate can be adjusted by pressure measurement within reactor vessel 10. For continuous inert gas purging, an outlet opening of appropriate size can be provided in a safe location (in the area of ​​flue 60 or in another inaccessible and non-hazardous location) to generate a flow 66 from reactor vessel 10.

[0070] As in accordance with Figure 5 In the embodiments, according to Figure 6 The reactor vessel 10 operates at a pressure level exceeding atmospheric pressure. Here, the reactor vessel 10 also has a discharge port 62, for example in the form of a rupture disc, which is configured to open under conditions exceeding a preset pressure level. However, a continuous flow of inert gas is not provided, thus no flow 66 is formed in this embodiment.

[0071] In this alternative embodiment of pressurized operation, for example, purging for initial inerting is performed only during operation preparation. During further operation, the amount of inert gas is increased only continuously or intermittently to equalize the leakage flow from the reactor vessel to the atmosphere. In this embodiment, therefore, there is no permanently open outlet for inert gas flow to the atmosphere during normal operation.

[0072] According to Figures 4 to 6 In some embodiments, it is advantageous to operate the reactor containing hydrocarbons only when the required oxygen content is insufficient.

[0073] According to Figure 4 and Figure 5In embodiments of continuous purging, the oxygen content is preferably measured in the exhaust gas downstream of reactor vessel 10 (e.g., in flue 60 or another exhaust line). Alternatively or concurrently, the oxygen content may also be measured at one or more locations within the reactor vessel 10 region using appropriate measurement methods (e.g., a tunable diode laser, a zirconia probe, a GC paramagnet). Figure 6 In some embodiments, the oxygen content can be similarly measured in the purge gas discharge line optionally used for initial inertization and / or in the reactor vessel 10 itself. Furthermore, according to Figure 5 and Figure 6 In some embodiments, the pressure inside the reactor vessel can be continuously measured and monitored to detect unacceptable loss of inert gas early.

[0074] As shown in the more detailed figures below, in all the previously shown embodiments, the flue 60 may have structural elements (so-called velocity seals / pipe guides) in the region of the flue wall to prevent air backflow (e.g., due to free convection flow) back to the reactor vessel 20.

[0075] Figure 7 The diagram schematically illustrates an extension of a reactor for carrying out a chemical reaction according to an embodiment of the present invention, relative to the illustration in the foregoing figures, wherein the element portions already described above are not shown again. For further illustration, particular reference is made to the above... Figure 4 .

[0076] As shown here, an additional ignition device or igniter 68 can be installed in the area of ​​flue outlet 63 to at least partially prevent unburned hydrocarbons from escaping into the atmosphere in the event of a disaster. As further shown, inert gas can be fed into reactor vessel 10 from different sides. The walls of reactor vessel 10 and the wall passages for fasteners or current input devices can advantageously be designed to be airtight, indicated by 15. I and O indicate the feed and removal of process gas from reaction tube 20.

[0077] Figure 8 A reactor for performing a chemical reaction according to an embodiment of the present invention is schematically shown, extending to... Figure 7 The representation of or variations thereof. Already concerning... Figure 7 The components explained here are no longer provided with reference numerals.

[0078] As shown here, the flue 60 may have suitable insulation material 69 in the area adjacent to the reactor vessel 10. The height h of the flue 70 may be, for example, 20 to 50 meters above the ground. A so-called velocity seal 66 may be provided in the flue 60.

[0079] Figure 9The principles of flue size design according to embodiments of the present invention are illustrated schematically in the form of a chart, wherein oxygen content is plotted as a percentage on the horizontal axis and in meters on the vertical axis. 3 The rate of volume increase related to the reaction is plotted in units of / s. Graph 601 shows the relationship already explained with reference to the table above. Dashed line 602 represents the value required for a maximum pressure increase of 20 mbar with a flue diameter of 500 mm; dashed line 603 represents the corresponding value with a flue diameter of 900 mm.

Claims

1. A reactor (100, 200) for carrying out a chemical reaction, comprising a reactor vessel (10), one or more reaction tubes (20), and a device (40) for electrically heating said one or more reaction tubes (20), wherein, The reaction tube (20) is guided through the reactor (100, 200) with at least one U-bend, or the reaction tube (20) passes through the reactor (100, 200) without a U-bend, characterized in that the reactor vessel (10) has one or more discharge ports (61, 62) that are permanently open or configured to open under conditions above a preset pressure level, the one or more discharge ports (61, 62) being connected to one or more flues (60), and is provided with a gas feed device (50) configured to feed inert gas into the reactor vessel (10) and adjust the amount of inert gas based on oxygen measurements in the reactor vessel (10) and / or the one or more flues (60), and is provided with a means configured to prevent the reaction operation if the oxygen content and / or pressure and / or hydrocarbon content measured in the reactor vessel (10) and / or in the discharge line downstream of the reactor vessel exceeds a corresponding preset value.

2. The reactor (100, 200) according to claim 1, wherein, The reactors (100, 200) are configured to carry out the chemical reaction at a temperature level above 500°C.

3. The reactor (100, 200) according to claim 2, wherein, The reactors (100, 200) are configured to carry out the chemical reaction at a temperature level of 500°C to 1000°C.

4. The reactor (100, 200) according to any one of claims 1 to 3, wherein, The one or more discharge ports (61) are permanently open.

5. The reactor (100, 200) according to any one of claims 1 to 3, wherein, The one or more discharge ports (62) are configured to close when the pressure is below the preset pressure level and to open temporarily or permanently when the preset pressure level is reached.

6. The reactor (100, 200) according to any one of claims 1 to 3, wherein, The gas feeding device (50) is configured to continuously feed the inert gas into the reactor vessel (10).

7. The reactor (100, 200) according to any one of claims 1 to 3, wherein, The gas feeding device (50) is configured to supply the inert gas to the reactor vessel (10) once or periodically.

8. The reactor (100, 200) according to claim 4, wherein, The reactor vessel (10) is configured to operate at a pressure level below atmospheric pressure and has means for generating an airflow from the reactor vessel (10).

9. The reactor (100, 200) according to claim 5, wherein, The reactor vessel (10) is configured to operate at a pressure level exceeding atmospheric pressure.

10. The reactor (100, 200) according to any one of claims 1 to 3, wherein, The gas feed device (50) is configured to provide a gas or gas mixture as the inert gas, the gas or gas mixture having a corresponding superatmospheric content of nitrogen, carbon dioxide, and / or argon.

11. The reactor (100, 200) according to claim 1, wherein, The gas feed device (50) is configured to adjust the maximum oxygen content in the reactor vessel (10) based on the size of the one or more flues (60).

12. A method for carrying out a chemical reaction, wherein, Using reactors (100, 200), said reactors (100, 200) having a reactor vessel (10), one or more reaction tubes (20), and a device (40) for electrically heating said one or more reaction tubes (20), wherein said reaction tubes (20) are guided through said reactors (100, 200) with at least one U-bend, or said reaction tubes (20) are guided through said reactors (100, 200) without a U-bend, characterized in that the reactor vessel (10) used is a reactor vessel (10) having one or more discharge ports (61, 62), said one or more The vents (61, 62) are permanently open or configured to open under conditions above a preset pressure level. The one or more vents (61, 62) are connected to one or more flues (60) and inert gas is fed into the reactor vessel (10) by means of a gas feed device (50) and the amount of inert gas is adjusted based on oxygen measurements in the reactor (10) and / or in the one or more flues (60). The reactor vessel is equipped with a device configured to prevent the reaction operation if the oxygen content and / or pressure and / or hydrocarbon content measured in the reactor vessel (10) and / or in the discharge line downstream of the reactor vessel exceeds a corresponding preset value.

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