High-temperature reactor

Abstract

In a tube bundle reactor for performing a catalytic gas-phase reaction, the reactor comprises a reaction tube (3) formed of a material having a first thermal expansion coefficient α1, and a gas inlet tube base (5) and a gas outlet tube base (8) and a reactor jacket (11) formed of a material having at least a second thermal expansion coefficient α2, wherein α2 > 1.13 * α1 or α2 < 0.88 * The coefficient of thermal expansion is α1, and the reactor jacket (11) is composed of three jacket portions (12, 13, 19) in the axial direction, the first jacket portion (12) is connected to the gas inlet tube base (5), the second jacket portion (13) is connected to the gas outlet tube base (8), both the first jacket portion (12) and the second jacket portion (13) are made of a material having at least a second coefficient of thermal expansion α2, and between the first jacket portion (12) and the second jacket portion (13) there is a third jacket portion (19) made of a material having a third coefficient of thermal expansion α3, and α2 > 1.13 * In the case of α1, α3 <= 0.99 * α2 is true, or α2 < 0.88 * For α1, α3 >= 1.01 * It is α2. Methods and uses for operating the tube bundle reactor have also been proposed.

Description

[Technical Field]

[0001] The present invention relates to a tube bundle reactor as described in the preamble of claim 1, a method for operating the tube bundle reactor, and the use of the tube bundle reactor. In particular, it relates to the production of carbon monoxide using a catalytic reverse water-gas shift (RWGS) reaction. [Background technology]

[0002] The tube bundle reactor is used for the RWGS reaction.

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[0003] Generally, reaction tubes and reactor jackets are made of similar materials with similar coefficients of thermal expansion. When the inflow is good, good heat transfer is achieved by the heat transfer medium salt in the jacket space of the tube bundle reactor, so the temperature of the reaction tubes and jacket space deviates only slightly from the temperature of the heat transfer medium. Therefore, the mechanical stress applied to the tube bundle reactor due to the difference in expansion caused by the temperature difference is small.

[0004] Patent Document 1 relates to a boiling water tube reactor for producing methanol, which has reaction tubes made of a metallic material that does not have catalytic activity with respect to the reaction gas. A further feature of this material is that its coefficient of thermal expansion is approximately the same as that of the reactor jacket material. As a suitable material for the reaction tubes, a mixed chromium steel of ferritic and austenitic steel has been proposed, which can be subjected to an inert coating or plating as needed.

[0005] Similarly, Patent Document 2 describes a tubular reactor that promotes the oxidation of olefins by using a reaction tube made of nickel-free chromium steel, the thermal expansion coefficient of the reaction tube being slightly lower than that of the carbon steel constituting the reaction vessel.

[0006] The load conditions differ when the reaction tube and reactor jacket are made of materials with different coefficients of thermal expansion. This situation arises when the reaction tube needs to be made of a particularly resistant material due to the corrosive properties of the reaction gas, while the reactor jacket, not subject to such conditions, can be made of a lower-cost material with a different coefficient of thermal expansion.

[0007] In Patent Document 3, the difference between the expansion of the reaction tube and the expansion of the reactor jacket is absorbed by a compensator within the reactor jacket. A similar configuration is known from Patent Document 4, which has a compensator within the reactor jacket in the region of the annular conduit. However, these configurations are only possible at relatively low pressures or relatively small reactor dimensions. While it is possible to solve this problem by using the same type of material, it would be costly.

[0008] Patent Document 5 describes how the adverse effects of thermal expansion in a heat exchange reactor are minimized by various measures such as flow guide plates through which tubes pass, insulating layers, and fins. In this case, the baffle plate has a lower coefficient of thermal expansion than the tube base.

[0009] Patent Document 6 relates to a tubular reactor with plating containing nickel applied to the tube base and an embodiment of a reaction tube made of a nickel base material. The outer jacket of this reactor has a sufficient thickness to absorb the tension that occurs when the expansion differs due to the temperature difference between the tube and the outer jacket.

[0010] Patent Document 7 describes a multi-stage method for producing hydrocarbons and alcoholic fuels using renewable energy sources. In this method, preferably, a tube bundle reactor is used in the RWGS process and the Fischer-Tropsch process. At this time, the RWGS tube bundle reactor is preferably heated with a liquid heat transfer medium composed of a liquid alloy, a liquid salt, or an organic heat transfer medium. The details of the structure of this tube bundle reactor are not disclosed. Examples of corresponding catalysts are described for various processes.

[0011] A similar method is described in Patent Document 8. This method is only related to the production of CO and is carried out in a single-stage gas circulation. The circulating gas is adjusted by known methods through the condensation of water and the separation of target components. The RWGS reactor is preferably composed of a tube bundle reactor operating with a liquid salt. The feed gas generally has a temperature from 5°C to 150°C and a pressure in the range from 1 bar to 200 bar. Preferably, the pressure is between 5 bar and 70 bar. At this time, the pressure value is understood as an absolute pressure, similar to all other pressure values within the scope of this document. The feed gas usually has a temperature from 200°C to 700°C, preferably from 450°C to 600°C, after heating and before flowing into the RWGS reactor. The reaction temperature preferably ranges from 500°C to 600°C. Preferably, a catalyst that suppresses methanation is used. The RWGS reactor preferably includes two catalyst beds, and the gas can be heated between them. The heat transfer medium is preferably introduced in countercurrent to the reaction gas and is heated electrically outside the reactor. The advantages include that metal dusting or methanation can be significantly avoided due to the lower operating temperature compared to known high-temperature processes, so that lower-cost materials can be used.

[0012] Patent Document 9 presents a method for producing liquid fuel from CO2 and water. In this case, the RWGS reaction forms an intermediate stage for producing a reaction gas containing CO and H2, and using this reaction gas, liquid fuel is finally produced through intermediate products such as methanol and DME (dimethyl ether). In the RWGS process, a catalytic tube reactor operating at 400 °C and 5 bar is used. For example, in other operating methods such as a temperature of 500 °C, a pressure of 50 bar, and an H2 / CO2 ratio of 2:1 in the feed gas, the conversion increases. The reaction heat in the RWGS process arises from an exothermic partial process.

[0013] Other RWGS processes are known from, for example, Patent Document 10, Patent Document 11, Patent Document 12, or Patent Document 13.

[0014] Non-Patent Document 1 proposes a demonstration plant for producing a flow-based liquid fuel. In this case, the RWGS reactor used is a known technology and is configured as a natural gas / biogas combustion reformer including a waste heat system and a steam generation system, and thus is a common plant configuration in the steam reforming of natural gas / biogas. This process is to be carried out using a common catalyst at a temperature range of 700 °C to 1000 °C and a maximum pressure of 30 bar. Preferably, an inlet pressure of 27 bar and a temperature of 900 °C are used. The electrically heated reactor is considered to be not yet complete.

[0015] The central problem in the RWGS process is the corrosion of materials due to "metal dusting". The mechanism of action of this type of corrosion has not yet been fully elucidated. In any case, the carbon activity "a cThe presence of a gas composition with strong carburizing properties, characterized by "[...]", is a prerequisite. The critical temperature range is approximately 400°C to 900°C. Between approximately 800°C and 900°C, metal dusting decreases again. Metal dusting is enhanced by high pressure of approximately 5 bar to 10 bar, or occurs only at this condition or above. This effect has been observed in various processes in petrochemical plants, such as catalytic reforming, ammonia and methanol production, and reduction plants. Synthesis gas is a typical corrosive gas of metal dusting. Synthesis gas is a basic raw material used in many synthesis reactions in the chemical industry. Synthesis gas mainly consists of hydrogen (H2), carbon monoxide (CO), and, in some cases, carbon dioxide (CO2), methane (CH4), or water vapor (H2O). g It is composed of small amounts of other substances such as ). In the corrosion process caused by metal dusting, elemental carbon and fine metal particles are formed. Iron, low-alloy steel, high-alloy steel, and cobalt or nickel-based alloys are susceptible to corrosion, while nickel-based alloys are relatively resistant. Nickel-based alloys that are particularly resistant have a high proportion of chromium (Cr) and aluminum (Al) and a low proportion of silicon (Si) and possibly copper (Cu). These alloy components form a protective oxide film. Furthermore, such alloys have a low iron content and clearly defined particle size. Recent developments include duplex steels. New alloys resistant to metal dusting are continuously being developed.

[0016] Non-patent document 2 describes various mechanisms of metal dusting and materials that are resistant to it.

[0017] Non-patent document 3 describes the corrosion mechanisms of various iron-based and nickel-based alloys. The carbon activity a depends on the gas composition, temperature, and pressure. cDetailed investigations have been conducted on this topic. Experiments were carried out using various alloys at temperatures of 482°C, 593°C, and 704°C. The incidence of metal dusting was highest at 593°C. In addition, the incidence increased with increasing pressure and exposure time. At atmospheric pressure and 593°C, metal dusting did not occur in almost all alloys, but it did occur at 14.3 bar. At higher pressures, the degree of corrosion depended not only on the quality of the alloy but also on the exposure time. The higher the alloy content of nickel, chromium, and aluminum, the lower the material's brittleness. These alloy components form a protective layer consisting of chromium oxide and aluminum oxide. Excellent resistance to metal dusting has been confirmed in nickel-based materials of Alloy602CA quality and above. Alloy693 shows even better resistance. Alloy601 has relatively low resistance.

[0018] These results are confirmed in Patent Document 14, which presents a similar nickel-chromium-aluminum alloy with excellent processability, creep strength, and corrosion resistance. Patent Document 15 presents a further alloy with resistance.

[0019] Patent Document 16 relates to a method for converting a supply gas containing CO2 and H2 into synthesis gas in a two-zone endothermic heat exchange reactor in which an exothermic reaction occurs in a first reaction zone and an endothermic reaction occurs in a second reaction zone. In this case, methane is produced in the first reaction zone, and the methane reacts again at a high temperature in the second reaction zone. The supply gas may optionally be preheated before flowing into the RWGS reactor. The heat transfer medium that transmits the reaction heat is preferably a gas. This application assumes that metal dusting occurs when using a gas containing CO, especially when the gas is cooled. Therefore, the reaction temperature is selected to be as high as possible to avoid metal dusting. The reaction temperature in the first reaction zone is preferably 500°C or higher (800°C, 900°C to 1000°C), and the reaction temperature in the second reaction zone is 600°C to 800°C. The synthesis gas can be directly combined with the heat transfer medium in various ways. The reaction heat to be introduced is supplied by an electric, combustion, or self-heating RWGS reactor. The pressure in the jacket chamber is between 2 bar and 50 bar, or between 50 bar and 200 bar. In the embodiment, the pressure is between 9.5 barg and 11.5 barg. When the fuel gas on the jacket side is combined with the reaction gas, the same pressure is produced throughout the reaction chamber. The type of reactor may be, for example, a conventional steam reformer. Patent document 16 does not consider materials resistant to metal dusting.

[0020] Therefore, in tube bundle type devices, it is known that differences in thermal expansion coefficients and / or temperature differences between the tubes and the jacket can result in differences in length expansion between the tubes and the device jacket. This difference in length expansion causes material stress in the device, and this material stress needs to be compensated for by appropriate measures such as sufficient wall thickness, compensators, or suitable materials. However, in cases where specific materials with different thermal expansion coefficients are essential for reasons of corrosion resistance and strength at high temperatures, and when the difference in length expansion exceeds a certain magnitude, measures known from prior art may not be applicable. [Prior art documents] [Patent Documents]

[0021] [Patent Document 1] U.S. Patent No. 4559207 [Patent Document 2] UK Patent Application Publication No. 724452 [Patent Document 3] European Patent Application Publication No. 1113238 [Patent Document 4] International Publication No. 2004 / 052525 [Patent Document 5] U.S. Patent Application Publication No. 2003 / 0173062 [Patent Document 6] International Publication No. 2009 / 092724 [Patent Document 7] International Publication No. 2008 / 115933 [Patent Document 8] International Publication No. 2022 / 263384 [Patent Document 9] International Publication No. 2007 / 108014 [Patent Document 10] International Publication No. 2022 / 129338 [Patent Document 11] International Publication No. 2021 / 062384 [Patent Document 12] International Publication No. 2003 / 070629 [Patent Document 13] International Publication No. 2021 / 225643 [Patent Document 14] International Publication No. 2013 / 182177 [Patent Document 15] International Publication No. 2006 / 121561 [Patent Document 16] International Publication No. 2022 / 253963 [Non-patent literature]

[0022] [Non-Patent Document 1] "Conceptual and technical configuration of a development platform for PtL fuels," https: / / www.now-gmbh.de / wp-content / uploads / 2021 / 08 / EPP_Abschlussbericht.pdf [Non-Patent Document 2] "Metal Dusting", https: / / www.corrosionguru.com / wp-content / uploads / 2017 / 12 / metaldusting.pdf [Non-Patent Document 3] "Development of Materials Resistant to Metal Dusting Degradation," Argonne National Laboratory, 2005, https: / / doi.org / 10.2172 / 890559 [Overview of the Initiative] [Problems that the invention aims to solve]

[0023] Therefore, the object of the present invention is to enable a tube bundle reactor, in general terms, to operate in a temperature range of 450°C to 650°C and an overpressure range of 5 bar to 50 bar, such that the material stress due to differences in thermal expansion resulting from differences in the thermal expansion coefficients of the reaction tubes and reactor jackets remains within an acceptable range, and such a tube bundle reactor can be manufactured economically. A further object is to configure the tube bundle reactor so that it can be used to carry out endothermic gas-phase reactions, particularly RWGS reactions, and gas-phase reactions in particular where the reaction gas has strong carburizing properties, which can lead to corrosion mechanisms such as metal dusting. [Means for solving the problem]

[0024] According to the present invention, this problem is solved by the features of claim 1 and by the claims relating to the method and use. Furthermore, the dependent claims indicate possible advantageous configurations.

[0025] The tube bundle reactor according to the present invention satisfies, based on process engineering requirements, one of the conditions of α2 > 1.13 * α1 or α2 < 0.88 * for α1.

[0026] The reactor jacket of the tube bundle reactor according to the present invention is composed of three jacket parts in the axial direction. The first part has an axial length L1A and is connected to the tube base on the gas inlet side. The second part has an axial length L2A and is connected to the tube base on the gas outlet side. Both parts are formed of a material having at least a second coefficient of thermal expansion α2. At this time, between the first jacket part and the second jacket part, a third jacket part having an axial length L3 and made of a material having a third coefficient of thermal expansion α3 is arranged, where α2 > 1.13 * in the case of α1, α3 < 0.99 * for α2, or α2 < 0.88 * in the case of α1, α3 > 1.01 * for α2.

[0027] When α2 is larger or smaller than α1, the reactor jacket and the reaction tubes expand differently with the increase in temperature. As a result, stress occurs in the device components, but this stress can be controlled by various methods according to the prior art, such as a jacket wall or a compensator of an appropriate thickness. These methods are such that the ratio of the coefficients of thermal expansion is α2 > 1.13 * α1 or α2 < 0.88 * for α1 in a large-scale tube bundle reactor related to practice with a device diameter of about 6 m to 8 m. When exceeding a specific limit value, it reaches that limit. If this ratio is exceeded, in the known design methods, the structure becomes uneconomical or technically infeasible.

[0028] The means of the present invention make it possible to manufacture a tube bundle reactor in which the materials used are resistant to metal dusting on the gas side and resistant to salt corrosion on the jacket side, and therefore enable a high conversion rate in the low-temperature operating range of, for example, the RWGS reaction. When it is necessary to use different materials for the reaction tube and the reactor jacket for reasons of corrosion and economy, a difference in axial expansion occurs, and correspondingly a large stress is generated in the material. However, according to the present invention, by using different jacket portions made of materials with different coefficients of thermal expansion, this stress can be reduced to an acceptable range. This creates optimal possibilities regarding process conditions and material use, because the tube bundle reactor can operate at high temperatures and pressures while minimizing the use of materials. The tube bundle reactor according to the present invention can be manufactured in dimensions that are uneconomical or technically impossible with known design methods.

[0029] In a preferred embodiment, both the reactor jacket and the tube base have an average axial thermal expansion coefficient α m =(α2 * (L1A+L1B+L2A+L2B)+α3 * It has L3) / (L1A+L1B+L2A+L2B+L3), and its ratio α m / α1 is in the range of 0.88 to 1.13, preferably in the range of 0.90 to 1.10, and particularly preferably in the range of 0.92 to 1.09. By selecting a material having an appropriate thermal expansion coefficient α3 and a ratio of the sum of the axial lengths L1A, L1B, L2A, L2B to L3, the condition α m / α1 <= 1.13 or α m The mean expansion coefficient α that satisfies / α1 ≥ 0.88 m You can obtain this.

[0030] ratio α m The ideal value of / α1 is exactly 1.0. However, due to structural constraints and the selection of available materials, it is usually impossible to maintain this ratio. Ratio α mIf / α1 remains within the required range, the material stresses resulting from different axial expansions within the tube reactor will be less than the allowable material stress at all locations and at all times. In this case, material stresses may arise if all components of the tube reactor are at the same temperature at all times while being heated to the operating temperature, or if different components of the tube reactor are at different temperatures as a result of different degrees of heating during heating.

[0031] The expansion of each length is given by the following relationship: ΔL = α * ΔT * L0 It is calculated as follows, and at this time, Expansion of ΔL [mm] length α[1 / K] Coefficient of thermal expansion ΔT[K] Temperature change L0 [mm] Each standard length That is the case.

[0032] The resulting material stress is obtained by a calculation method known to those skilled in the art. For example, DIN EN 13445-3:2021-12, 13.5.9 or ASME BPVC.VIII.1-2021, UHX-13, and especially UHX-13.6, a part thereof, may be applied.

[0033] In practical configurations, efforts should be made to use as little material as possible. Correspondingly, it is appropriate to use the same material for the reactor hood as for the tube base and the jacket portion connected to the tube base. However, if different materials, and in some cases materials with different coefficients of thermal expansion, are used, α m The calculation equations related to this need to be extended as appropriate.

[0034] A known issue when welding different types of materials is that welded joints made of high-strength carbon steel must be heat-treated after welding. This is not necessary for stainless steel. Heat-treating an entire tube bundle reactor is very expensive, so attempts are made to avoid it whenever possible.

[0035] When welding high-strength carbon steel and stainless steel, a buffer layer made of stainless steel is provided at the weld edges of the intermediate jacket portion, and heat treatment is performed as needed. The burden of heat treatment on this spatially narrow and limited area is minimal. Therefore, all weld joint edges of the jacket portion are formed from stainless steel, and post-weld heat treatment is no longer required. Details of such methods are known for various applications, for example, from U.S. Patent No. 2,963129, International Publication No. 2000 / 032350, or International Publication No. 2015 / 091681. They are also described in regulations such as ASME BPVC Sec. IX, QW-283.

[0036] In an advantageous embodiment of the present invention, α2 > 1.13 * α1 and α3 <= 0.99 * α2 and α3 <= α1.

[0037] Since stainless steel generally has a high coefficient of thermal expansion, the coefficients of thermal expansion α2 of the first and second jacket portions are usually greater than the coefficient of thermal expansion α1 of the reaction tube: α2 > α1. To compensate, the coefficient of thermal expansion α3 of the third jacket portion must be smaller: α3 < α2. In a preferred embodiment, this coefficient of thermal expansion is at most the same as the coefficient of thermal expansion α1 of the reaction tube material: α3 <= α1.

[0038] α3 <= 0.99 * By using the third jacket portion of α2, the overall axial expansion of the reactor jacket length is reduced. On the other hand, the stainless steel of the first and second jacket portions expands more radially than the third jacket portion, which is made of carbon steel. These effects are taken into account in the corresponding strength calculations to determine the required wall thickness.

[0039] Within certain temperature and pressure ranges, synthesis gas can cause metal dusting in some materials. A further prerequisite is the so-called carbon activity. If the carbon activity is clearly greater than 1, metal dusting is expected. This prerequisite is typically given under the preferred operating conditions considered here. Therefore, in a preferred embodiment, the reaction tube is formed from a material resistant to the corrosive properties of the process gas at a selected gas composition, selected pressure, and selected temperature. In this case, the reaction tube is preferably entirely formed from this corrosion-resistant material for safety and manufacturability reasons.

[0040] In an advantageous further development of the present invention, the reaction tube is formed of a nickel-based alloy. Many different materials are known from this class and can be used in the reactor according to the present invention. Particularly suitable are alloys selected from materials Alloy601, Alloy602CA, Alloy693, Alloy699XA, or materials comparable thereto. “Comparable materials” as used herein is understood to mean materials classified as equivalent in other nomenclature systems. For example, UNS material N06025, or material number 2.4633-NiCr25FeAlY in German, is comparable to Alloy602CA, the material used herein, and this name is a common abbreviation of the full name “VDM® Alloy602CA”. Equivalent materials in other nomenclature systems have nearly the same composition and the same mechanical properties, although they may differ slightly from those of the reference material. The corrosion resistance of these materials increases in the order listed. These materials represent the most advantageous selections of currently available materials. In this case, the selection of the reaction tube material is preferably carried out according to a predetermined selection procedure that determines the required quality of the material depending on a decisive parameter. This procedure ensures that only the material quality actually required for the application case at the time is used. In this way, costs can be kept within the necessary range. The materials listed should not be interpreted as mutually exclusive. They are merely preferred choices when there is a risk of metal dusting. Other materials may be used in other applications.

[0041] In most cases, the material Alloy602CA is used. This represents a good compromise between corrosion resistance and price. In specific cases, such as when the risk of material corrosion due to metal dusting is low, for example, at low pressures, or when the expected operating time of the reactor is short, such as in laboratory test reactors, the material Alloy601 can also be used. Materials with high corrosion resistance, such as Alloy683 or Alloy699XA, are used when required due to boundary conditions. This choice is not exclusive. New alloys are constantly being developed that can also be used in the tube bundle reactors according to the present invention.

[0042] In preferred embodiments of the present invention, the tube base, gas inlet hood, gas outlet hood, and first and second jacket portions are formed from high heat-resistant stainless steel, such as material SS316 or a comparable material, and the third jacket portion is formed from high heat-resistant low-alloy carbon steel, such as material SA387 Gr.22 Cl.2 or a comparable material. Material SS316 or a comparable material is particularly excellent due to its combination of features: excellent high-temperature strength, no need for heat treatment, corrosion resistance, and cost.

[0043] The thermal expansion coefficient of the material SA387 Gr.22 Cl.2 or a comparable material for the third jacket section is smaller than that of the first and second jacket sections and smaller than that of the reaction tube material. Furthermore, this material has excellent strength even at high temperatures and is relatively inexpensive. Therefore, efforts should be made to maximize the proportion of the jacket length L3. On the other hand, lengths L1A and L2A must be large enough to accommodate the annular conduit in that region. To compensate for expansion, there must be sufficient spacing in the direction of the jacket sections located between them. This will result in a smooth transition where different radial expansions in the weld line region can be compensated for. Other relevant rules should also be considered.

[0044] Therefore, the ideal state can be approached by, for example, the following combination of materials: Nickel-based material for reaction tubes Alloy602CA:α 602CA =14.8 * 10 -6* K -1 Stainless steel SS316:α for tube bases, etc. SS316 =18.64 * 10 -6* K -1 Carbon steel SA387 Gr.22 Cl.2:α for the third jacket portion S387 =14.48 * 10 -6* K -1

[0045] If the configuration is not according to the present invention, the third jacket portion does not exist. Assuming that the length of the reaction tube on one side is the same as the combined length of the reactor jacket and tube base on the other side, in this combination of materials, α1 = α 602CA alpha m =α². Therefore, α m / α1 becomes 1.26, which falls outside the range of the thermal expansion coefficient ratio according to the present invention. Under these boundary conditions, when the tube bundle reactor rises to its operating temperature, or at the latest when operating under pressure load, the allowable material properties are exceeded, resulting in plastic deformation and failure.

[0046] Therefore, in the configuration according to the present invention, a third jacket portion made of carbon steel is used. In this example, the third jacket portion has a thermal expansion coefficient that is smaller than that of the first and second jacket portions and even smaller than that of the reaction tube.

[0047] However, another case may arise in which the second thermal expansion coefficient α2 is smaller than the thermal expansion coefficient α1 of the reaction tube, and the third thermal expansion coefficient α3 is larger than the second thermal expansion coefficient α2. This may occur when the reaction tube is made of stainless steel and the reactor jacket is made of carbon steel. In this case, for example, the third jacket portion of length L3 is preferably formed from a material having a thermal expansion coefficient similar to that of the reaction tube, in which case materials from the group of stainless steels are suitable.

[0048] Advantageously, on the gas side, the tube base, gas inlet hood, and / or gas outlet hood are plated with a nickel-based material from the material group for the reaction tubes. The type of nickel-based material is determined in the same way as the material for the reaction tubes. For example, stainless steel is specified as the material for the gas inlet hood, gas outlet hood, and tube base. The susceptibility of the material to metal dusting under operating conditions is then investigated. Typically, the supply gas is at a lower temperature than the reaction temperature. Under such conditions, the reaction equilibrium of the RWGS reaction lies on the side of the reaction extracts, i.e., CO2 and H2. Therefore, it becomes less susceptible to metal dusting. Depending on its properties, the selected material may be used without additional protective measures, or it may be protected with a metal dusting-resistant plating. In this case, the resistance may be lower than that of subsequent tube bundle reactor components, which are exposed to higher carbon activity due to higher temperatures, higher pressures, and more corrosive gas compositions. A plating method, for example, is explosive bonding. The tube base is usually always plated, preferably with the same material as the reaction tube. This facilitates welding the reaction tube to the tube base.

[0049] Preferably, the third jacket portion is plated with a material that is corrosion-resistant to the heat transfer medium, and this plating extends over the axial length in the range of 1 mm to 100 mm within the adjacent first and second jacket portions, which are closely connected to each other. The use of molten carbonate salts allows for process control at high temperatures. However, within the limits of use, molten salts are highly corrosive due to decomposition reactions into oxides that combine with many materials at certain temperatures. The material of the third jacket portion has excellent strength at high temperatures, but is not usually corrosion-resistant to molten carbonate, so it is plated to protect it from the heat transfer medium. Typically, the same material that formed the first and second jacket portions is used. Preferably, material SS316 or of higher quality is used. The plating is carried out by methods known from the prior art.

[0050] In tube bundle reactors for the most important exothermic gas-phase reactions, the inner diameter of the tubes is typically in the range of 21 mm to 26 mm. This tube diameter provides a cooling surface density that can reliably dissipate the reaction heat of hot spots, which frequently occur, especially in exothermic gas-phase reactions. In endothermic gas-phase reactions, such hot spots do not exist, so in this case, the heating surface density can be reduced by increasing the inner diameter of the tubes to a certain extent. This reduces the number of tubes and lowers the manufacturing cost of the tube bundle reactor. Therefore, in further embodiments of the present invention, the inner diameter of the reaction tubes is in the range of 30 mm to 60 mm. Larger inner diameters of reaction tubes are also possible, but care must be taken in process design to ensure that heat transfer is still sufficient.

[0051] In an advantageous embodiment, the tube bundle reactor according to the present invention has at least one modular E-heater for heating a heat transfer medium, the term "E-heater" being understood to mean an electrically driven heater. This E-heater is preferably located in parallel with the circulation pump of the tube bundle reactor. The heat transfer medium is led from the pressure side of the circulation pump to the E-heater and from the E-heater to the upstream side of the circulation pump. The flow of the heat transfer medium through the E-heater is controlled by an optional control valve. If necessary, at least one additional E-heater is connected downstream of at least one first E-heater. The modular structure of the E-heaters allows for easy expansion of the output. Preferably, these additional E-heaters are located in parallel with the first E-heater. This facilitates access for assembly and maintenance work, particularly with respect to the heating rods. To achieve zero-emission operation, preferably all E-heaters are powered by electricity generated from renewable energy.

[0052] In preferred embodiments, the reaction temperature is in the range of 450°C to 650°C. In more preferred embodiments, the reaction temperature is in the range of 500°C to 550°C. This temperature range is sufficiently high with respect to the highest possible conversion rate, while still low enough to allow for a sufficient selection of economical materials. At lower temperatures, the tendency to corrode decreases on both the gas and heat transfer medium sides, and the thermal and mechanical stress on the tube bundle reactor decreases, but this also reduces the conversion rate and product yield. The opposite effect occurs at temperatures above the upper limit.

[0053] Advantageously, the gas chamber pressure is in the range of 5 to 50 bar absolute pressure, more preferably 10 to 35 bar absolute pressure. These pressure ranges are optimal in terms of maximizing mass flow rate and conversion efficiency, while limiting structural costs. Structural costs mainly arise from mechanical stresses that contribute to the corresponding wall thickness. On the other hand, as the corrosive properties of the process gas increase with increasing pressure, the requirements for material quality also increase.

[0054] In another preferred embodiment, a mixture of carbonates, or a mixture of nitrates and nitrites, preferably a molten solar salt, is used as the heat transfer medium.

[0055] Molten salts consisting of mixtures of nitrates and nitrites have often been proven effective as heat transfer fluids in tube bundle reactors. A ternary eutectic salt mixture called HITEC (trademark), consisting of 7% NaNO3, 53% KNO3, and 40% NaNO2, is known, with a melting point of 142°C and an operating temperature range up to approximately 540°C. The decomposition process begins within the upper temperature range. In solar power plants, "solar salt," a mixture of 60% NaNO3 and 40% KNO3, is often used. Here, the melting point is approximately 240°C, and the operating temperature limit is approximately 600°C. Decomposition can be mitigated by protective gases and additional pressurization.

[0056] Hydrogen is known to diffuse through metals. In this case, the diffusion flow depends on pressure, temperature, and the type of metal. When the nitrate / nitrite of the heat transfer medium salt decomposes to produce oxygen, the gas atmosphere over the heat transfer medium salt must be thoroughly cleaned to prevent the formation of an explosive atmosphere. Therefore, nitrate mixtures are fundamentally suitable as heat transfer media for the tube bundle reactor according to the present invention, provided that no hydrogen-containing process gas is used and the operating temperature is not too high.

[0057] For higher operating temperatures, a molten mixture of carbonates is preferably used as the heat transfer medium due to its high heat resistance. However, any other composition may be used if it is beneficial for the application. It is advantageous to layer a protective gas consisting of CO2 over the molten carbonate.

[0058] The tube bundle reactor according to the present invention is particularly suitable for processes in which the reactor jacket and reaction tubes are subjected to various loads resulting from, for example, high operating pressure of the process gas, high temperature, or materials having different physical properties. The tube bundle reactor is particularly suitable for endothermic catalytic gas-phase reactions.

[0059] The tube bundle reactor according to the present invention is preferably used to carry out catalytic gas-phase reactions selected from the production of styrene, formaldehyde, methyl ethyl ketone (MEK), and hydrogen cyanide; dehydrogenation of alkanes; dehydrogenation of alcohols; reverse water-gas shift reaction (RWGS); steam reforming of methane or ethanol; cracking of ammonia, methane, or methanol; catalytic naphtha reforming of a mixture of aromatic hydrocarbons benzene, toluene, and three xylene isomers (BTX aromatic compounds); oxidative coupling of methane (OCM); production of acetaldehyde, benzene, acrylonitrile, nitric acid, and methyl mercaptan; oxidation of sulfur dioxide to sulfur trioxide; and production of kerosene from methanol through olefin synthesis. In endothermic reactions, the heat of reaction required has traditionally been supplied mainly by the combustion of fossil fuels. In the tube bundle reactor according to the present invention, the heat of reaction required is preferably supplied to the process gas via an E-heater and a heat transfer medium as an intermediate medium, using electricity generated from renewable energy.

[0060] In particular, the tube bundle reactor according to the present invention is suitable for processes in which a catalytic gas-phase reaction is carried out by a reverse water-gas shift reaction to produce CO. The CO2 required for this reaction can be obtained to some extent from bio-based sources such as biogas, carbon-containing waste, or by-products of many industrial processes. A further possibility is separation from ambient air. This method is more costly, but this source is available everywhere and virtually unlimited. The hydrogen that is further required can preferably be obtained using an electrolytic cell that decomposes water into hydrogen and oxygen. The power to operate the plant for separating CO2 and obtaining H2 is preferably generated from renewable energy sources such as wind power or solar power.

[0061] The present invention will be described in more detail below with reference to the drawings. The following are the drawings shown. [Brief explanation of the drawing]

[0062] [Figure 1] This is a longitudinal cross-sectional view of an embodiment of the tube bundle reactor according to the present invention. [Figure 2] This is a top view of the embodiment shown in Figure 1, which includes both the circulation pump and the E-heater. [Figure 3] Figure 2 shows a longitudinal cross-sectional view of the circulation pump and two E heaters along line AB. [Modes for carrying out the invention]

[0063] Figure 1 shows a longitudinal section of a preferred embodiment of a schematic tube bundle reactor 1 for carrying out a catalytic gas-phase reaction. For clarity, typical peripheral equipment such as circulation pumps, coolers, and heaters are not shown. The tube bundle reactor 1 has a tube bundle 2 of reaction tubes 3 filled with a catalyst, the reaction tubes 3 being made of a material having a first coefficient of thermal expansion α1 and flowing through it with a process gas 4. In this example, the process gas 4 flows from top to bottom through the tube bundle reactor 1. Flow from bottom to top is also possible. In this case, the following names, which depend on the direction of flow, change accordingly.

[0064] The reaction tube 3 opens at its gas inlet end to the tube base 5 on the gas inlet side and is tightly connected to the tube base 5 at that end. The tube base 5 is covered by a gas inlet hood 6 equipped with a gas inlet conduit 7 and is tightly connected to the gas inlet hood 6. In this case, the type of connection depends on the respective application. In the case of high pressure of approximately 10 bar or more, or when an airtight seal is required, the tube base 5 and the gas inlet hood 6 are preferably welded to each other, but flange connection is also basically possible. The reaction tube 3 opens at its gas outlet end to the tube base 8 on the gas outlet side and is tightly connected to the tube base 8 at that end. The tube base 8 on the gas outlet side is covered by a gas outlet hood 9 equipped with a gas outlet conduit 10 and is tightly connected to the gas outlet hood 9. The type of connection on the gas outlet side is described in the same way as on the gas inlet side.

[0065] The tube bases 5 and 8, the gas inlet hood 6, the gas inlet conduit 7, the gas outlet hood 9, and the gas outlet conduit 10 are plated on the gas side with nickel-based material from the material group of the reaction tube 3 (5a, 8a, 6a, 7a, 9a, 10a).

[0066] The tube bundle 2 is surrounded by a reactor jacket 11 consisting of multiple parts, which is tightly connected to the upper gas inlet tube base 5 and the lower gas outlet tube base 8. All parts of the tube bundle reactor 1 are preferably connected to each other by welding.

[0067] High heat-resistant stainless steel is preferably used as the material for the tube bases 5 and 8, the gas inlet hood 6 and the gas outlet hood 9, and the jacket portions 12 and 13 that are directly connected.

[0068] The reactor jacket 11 consists of a first jacket portion 12 having an axial length L1A connected to the upper tube base 5, and a second jacket portion 13 having an axial length L2B connected to the lower tube base 8. The upper tube base 5 has a thickness of L1B, and the lower tube base 8 has a thickness of L2B. The first and second jacket portions 12 and 13 are made of a material having a second coefficient of thermal expansion α2. The first jacket portion 12 is surrounded by a first upper annular conduit 14 near the upper tube base 5, thereby allowing the heat transfer medium to be discharged from the jacket space 15 of the tube bundle reactor 1 through the opening 16 of the first jacket portion 12. Similarly, the second jacket portion 13 is surrounded by a second lower annular conduit 17 near the lower tube base 8, thereby allowing the heat transfer medium to be introduced into the jacket space 15 through the opening 18 of the second jacket portion 13. Heat transfer from the heat transfer medium to the reaction tube 3 in the jacket space 15 is optimized by a known flow induction device, although not shown in the diagram. Flow induction from top to bottom is also possible. In this case, the units connected to the tube bundle reactor need to be adjusted as appropriate due to their structure.

[0069] A third jacket portion 19 having an axial length L3 and a third thermal expansion coefficient α3 is inserted between the first and second jacket portions 12 and 13. In this case, the second thermal expansion coefficient α2 of the first and second jacket portions 12 and 13 is greater than the thermal expansion coefficient α1 of the reaction tube 3, and the third thermal expansion coefficient α3 is smaller than the thermal expansion coefficient α2 of the first and second jacket portions 12 and 13, preferably even smaller than the thermal expansion coefficient α1 of the reaction tube 3.

[0070] ratio α m / α1 is in the range of 0.88 to 1.13, preferably in the range of 0.90 to 1.10, and more preferably in the range of 0.92 to 1.09. In this case, α m α is the average thermal expansion coefficient of parts L1A, L1B, L2A, L2B, and L3, and α m =(α2 * (L1A+L1B+L2A+L2B)+α3 * The formula is L3) / (L1A+L1B+L2A+L2B+L3).

[0071] The specified ratio α m Due to / α1, the expansion of each length is smaller than a predetermined maximum value, and at the predetermined maximum value, the material stress in the tube bundle reactor 1 is smaller than the allowable material stress at all locations and at all times.

[0072] The first length expansion occurs when the tube bundle reactor 1 is heated from ambient temperature to operating temperature. During the heating process, care is taken to ensure that the temperature change over time does not exceed a predetermined maximum value, so that the material is not damaged by excessively large local differences in length expansion. When the gas chamber pressure rises to the operating pressure, further length expansions occur. Examples of such loads are considered within the scope of strength calculations.

[0073] The third jacket portion 19 is plated 19a with a material that is corrosion-resistant to the heat transfer medium, and this plating 19a extends over an axial length 19b in the range of 1 mm to 100 mm within the adjacent first and second jacket portions 12 and 13, and is tightly connected to them.

[0074] The top view of Figure 2 shows the gas inlet conduit 7 leading to the gas inlet hood 6. On the right side, a connecting conduit 20 extends from the upper annular conduit 14 to the first circulation pump 21. From this pump, a connecting conduit 22, shown in Figure 3, leads to the first E-heater 23, which is connected to the second E-heater 25 by a connecting conduit 24. This E-heater 25 is connected to the circulation pump 21 by a connecting conduit 26. A third E-heater 27 and a fourth E-heater 28 are connected to these two E-heaters 23 and 25 in a mirror image configuration. Similarly, four more E-heaters 30, 31, 32, and 33 are connected to the circulation pump 29 on the opposite side. The number of E-heaters depends on the heat demand of each tube bundle reactor 1. The number can be decreased or increased. E-heaters 23, 25, 27, 28, 30, 31, 32, and 33 are identical in their basic structure, i.e., they have a modular structure. This simplifies the complexity of the design and construction and reduces costs. All E heaters 23, 25, 27, 28, 30, 31, 32, and 33 are connected to the tube bundle reactor 1 by supports not shown here.

[0075] Figure 3 shows a longitudinal section along the cutting line AB shown in Figure 2. The circulation pump 21 feeds the heat transfer medium 34 flowing from the upper annular conduit 14 downwards into the lower annular conduit 17. From the lower pump housing 35, a connecting conduit 22 leads to the first E heater 23. In the first E heater 23, the heat transfer medium 34 is heated by an electrically driven heating plug 36 and flows upward as needed, influenced by a guide plate. The heat transfer medium 34 flows downwards through the vertical connecting conduit 24 to the inlet of the second E heater 25, through which the heat transfer medium flows in the same manner as the first E heater 23. The E heaters 23 and 25 preferably have the same structure so as to facilitate the modular structure shown in Figure 2. The flow of the heat transfer medium through the E heater unit is controlled by an optional control valve 37. To accommodate changes in reactor length, the pump housing 35 preferably includes a compensator 38. The shown configuration should not be considered limiting. Depending on the application, the configuration may be modified by those skilled in the art within the scope of the present invention. For example, the control valve may be positioned between the first E heater and the second E heater, or the E heaters may be arranged in a triangle, for example, rather than in a straight line in the top view. Furthermore, the E heaters may be arranged in parallel, in series, or a combination thereof, depending on the purpose. [Explanation of symbols]

[0076] 1 tube bundle reactor 2 tube bundle 3 reaction tubes 4. Process gas 5. Base of the gas inlet tube 6. Gas Inlet Hood 7. Gas inlet conduit 5a, 6a, 7a Plating of the gas inlet tube base, gas inlet hood, and gas inlet conduit 8. Base of the gas outlet tube 9. Gas outlet hood 10 Gas outlet conduit 8a, 9a, 10a Plating of the gas outlet side tube base, gas outlet hood, and gas outlet conduit 11 Reactor jacket 12. First jacket section 13. Second jacket section 14. First upper annular conduit 15 Jacket Space 16. Opening of the first jacket section 17. Second lower annular conduit 18. Opening of the second jacket section 19. Third jacket section 19a Plating of the third jacket portion 19b Overlap of plating 19a 20 connecting conduits 21 First circulation pump 22 Connecting conduits 23. First E heater 24 connecting conduits 25. Second E heater 26 Connecting conduits 27. Third E heater 28. Fourth E heater 29. Second circulation pump 30, 31, 32, 33 Further E-heaters 34 Heat transfer medium 35 Lower pump housing 36 Heating plug 37 Control valve 38 Compensator

Claims

1. A tube bundle reactor for performing a catalytic gas-phase reaction, First thermal expansion coefficient α １ A tube bundle (2) of a reaction tube (3) formed of a material having a catalyst that is filled in the operating state, through which a process gas (4) flows and a heat transfer medium flows around it, A gas inlet side tube base (5) having an axial dimension L1B is tightly connected to the gas inlet end of the reaction tube (3), through which the reaction tube (3) passes when it opens into a gas inlet hood (6) having a gas inlet conduit (7), and the gas inlet hood (6) covers the gas inlet side tube base (5) and is tightly connected to the gas inlet side tube base (5), A gas outlet side tube base (8) having an axial dimension L2B is tightly connected to the gas outlet end of the reaction tube (3), through which the reaction tube (3) passes when it opens into a gas outlet hood (9) having a gas outlet conduit (10), wherein the gas outlet hood (9) covers the gas outlet side tube base (8) and is tightly connected to the gas outlet side tube base (8), and further, A reactor jacket (11) surrounds the tube bundle (2) of the reaction tube (3) and is connected to the gas inlet tube base (5) and the gas outlet tube base (8), wherein the gas inlet tube base (5), the gas outlet tube base (8) and / or the reactor jacket (11) have at least a second coefficient of thermal expansion α ２ A reactor jacket (11) is formed of a material having the following characteristics: In a tube bundle reactor having, α ２ > 1.13 ＊ α １ or α ２ <0.88 ＊ α １ And, The reactor jacket (11) is composed of three jacket parts (12, 13, 19) in the axial direction. The first jacket part (12) has an axial length L1A and is connected to the gas inlet side tube base (5). The second jacket part (13) has an axial length L2A and is connected to the gas outlet side tube base (8). Both the first jacket part (12) and the second jacket part (13) are formed of a material having at least a second coefficient of thermal expansion α ２ Between the first jacket part (12) and the second jacket part (13), there is a third jacket part (19) having an axial length L3 and made of a material having a third coefficient of thermal expansion α ３ α ２ > 1.13 ＊ α １ In the case of ３ <= 0.99 ＊ α ２ or, α ２ < 0.88 ＊ α １ In the case of ３ >= 1.01 ＊ α ２ A tube bundle reactor characterized by the above.

2. The reactor jacket (11), the gas inlet tube base (5), and the gas outlet tube base (8) all have an average axial thermal expansion coefficient α ｍ = (α ２ ＊ (L1A+L1B+L2A+L2B)+α ３ ＊ It has L3) / (L1A+L1B+L2A+L2B+L3) and its ratio α ｍ / α １ The tube bundle reactor according to claim 1, characterized in that the value is in the range of 0.88 to 1.

13.

3. α ２ > 1.13 ＊ α １ and α ３ <= 0.99 ＊ α ２ and α ３ <=α １ The tube bundle reactor according to claim 1, characterized in that it is the same as described above.

4. The tube bundle reactor according to claim 1, characterized in that the reaction tube (3) is formed from a material that is resistant to the corrosive properties of the process gas at a selected gas composition, a selected pressure, and a selected temperature.

5. The tube bundle reactor according to claim 1, characterized in that the reaction tube (3) is formed from a nickel-based alloy selected from materials Alloy 601, Alloy 602CA, Alloy 693, Alloy 699XA, or comparable materials.

6. The tube bundle reactor according to claim 1, characterized in that the gas inlet tube base (5), the gas outlet tube base (8), the gas inlet hood (6), the gas outlet hood (9), the first jacket portion (12), and the third jacket portion (13) are formed from high heat-resistant stainless steel, and the third jacket portion (19) is formed from high heat-resistant low-alloy carbon steel.

7. The tube bundle reactor according to claim 1, characterized in that the gas inlet tube base (5), the gas outlet tube base (8), the gas inlet hood (6), and / or the gas outlet hood (9) are plated (5a, 8a, 6a, 9a) on the gas side with a nickel-based material from the material group of the reaction tube (3).

8. The tube bundle reactor according to claim 1, characterized in that the third jacket portion (19) is plated with a material that is corrosion-resistant to the heat transfer medium (34), and the plating (19a) extends over an axial length (19b) in the range of 1 mm to 100 mm within the adjacent first jacket portion (12) and second jacket portion (13), and is tightly connected to the first jacket portion (12) and second jacket portion (13), respectively.

9. The tube bundle reactor according to claim 1, characterized in that the inner diameter of the reaction tube is in the range of 30 mm to 60 mm.

10. The tube bundle reactor according to claim 1, characterized in that it is provided with at least one modular E-heater (23) for heating the heat transfer medium.

11. A method for operating a tube bundle reactor (1) according to any one of claims 1 to 10, characterized in that the reaction temperature is in the range of 450°C to 650°C.

12. The method according to claim 11, characterized in that the pressure inside the gas chamber is in the range of absolute pressure from 5 bar to 50 bar.

13. The method according to claim 11, characterized in that a mixture of carbonates or a mixture of nitrates and nitrites is used as the heat transfer medium (34).

14. Use of the tube bundle reactor (1) according to any one of claims 1 to 10 for carrying out catalytic gas-phase reactions selected from the production of styrene, formaldehyde, methyl ethyl ketone (MEK), hydrogen cyanide, dehydrogenation of alkanes, dehydrogenation of alcohols, reverse water-gas shift reaction (RWGS), steam reforming of methane or ethanol, cracking of ammonia, methane or methanol, catalytic naphtha reforming to a mixture of aromatic hydrocarbons consisting of benzene, toluene and three xylene isomers (BTX aromatic compounds), oxidative coupling of methane (OCM), production of acetaldehyde, benzene, acrylonitrile, nitric acid, methyl mercaptan, oxidation of sulfur dioxide to sulfur trioxide, and production of kerosene from methanol through olefin synthesis.

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