Segmented temperature-controlled methanation reactor

Abstract

This invention relates to the field of chemical reaction equipment technology, and provides a segmented temperature-controlled methanation reactor. It includes an outer shell; a tubular reactor / heat exchanger disposed within the outer shell; and a coiled-tube reactor disposed within the outer shell, its top connected and communicating with the bottom of the tubular reactor / heat exchanger; a sealing annular gap is formed between the outer shell and the inner shell, the outer side communicating with the feed gas inlet, and the inner side communicating with the interior of the tubular reactor / heat exchanger through an opening in the inner cylinder; a central outer tube, disposed within the tubular reactor / heat exchanger, extending axially to the lower part of the coiled-tube reactor; the shell side of the coiled-tube reactor is used to fill ceramic balls and catalyst, while the tube side of the tubular reactor / heat exchanger is used to fill ceramic balls or to fill ceramic balls and catalyst; the feed gas enters the coiled-tube reactor from the tubular reactor / heat exchanger, and the product gas exits from the product gas outlet through the tubular reactor / heat exchanger. Temperature control is simple, the process flow is shortened, and the difficulty of catalyst loading is reduced.

Description

Technical Field

[0001] This invention relates to the field of chemical reaction equipment technology, specifically to a segmented temperature-controlled methanation reactor. Background Technology

[0002] Methanation is characterized by strong exothermic reaction and thermodynamic equilibrium control. Currently, the methanation technology used in industrialized coal-to-natural-gas projects in China is a multi-stage adiabatic fixed-bed process. In this process, the main reactor outlet temperature is relatively high, and the carbon conversion rate is limited by equilibrium, thus requiring a large amount of product gas to be recycled to dilute the inlet feed gas and reduce the inlet temperature and partial pressure.

[0003] In comparison, temperature-controlled methanation processes offer significant advantages such as lower outlet temperatures, higher single-pass conversion rates, and simpler process flows, demonstrating considerable development potential. However, the performance of this type of reactor depends on its heat transfer capacity. In recent years, wound reactors have attracted widespread attention due to their large heat exchange area, as disclosed in numerous patents. However, this type of reactor suffers from difficulties in catalyst loading, limiting its industrial application.

[0004] In the process of producing natural gas from coal or biomass, the hydrogen-to-carbon ratio of the feed gas needs to be adjusted through a shift reaction. Similar to the methanation process, this process route often involves multiple reactors connected in series and parallel, resulting in a relatively long process flow.

[0005] Therefore, existing methanation reaction equipment suffers from drawbacks such as difficulty in controlling reactor temperature, difficulty in catalyst loading, and long process routes. Summary of the Invention

[0006] In view of this, the present application provides a segmented temperature-controlled methanation reactor to overcome the shortcomings of existing methanation reactors, such as difficulty in temperature control, difficulty in catalyst loading, and long process routes.

[0007] This application provides a segmented temperature-controlled methanation reactor, comprising:

[0008] The outer casing has a raw material gas inlet and a heat transfer medium inlet on the side wall, a product gas outlet on the top, and a heat transfer medium outlet on the bottom.

[0009] A tubular reactor / heat exchanger is installed inside the outer shell, with its top connected to the product gas outlet;

[0010] A coiled reactor is disposed within the outer shell, with its top connected and communicating with the bottom of the tubular reactor / heat exchanger.

[0011] The inner shell is formed by axially connecting the outer wall of the tubular reactor / heat exchanger and the outer wall of the coiled reactor. A sealing annular gap is formed between the outer shell and the inner shell. The outer side of the sealing annular gap is connected to the raw gas inlet, and the inner side is connected to the inside of the tubular reactor / heat exchanger through the opening of the inner cylinder on the outer wall of the tubular reactor / heat exchanger.

[0012] A central outer tube is disposed inside the tubular reactor / heat exchanger and extends axially to the lower part of the coiled reactor;

[0013] A heat transfer medium channel is used to connect the heat transfer medium inlet and the heat transfer medium outlet;

[0014] The shell side of the coiled reactor is used to fill ceramic balls and catalyst, and the tube side of the tubular reactor / heat exchanger is used to fill ceramic balls or to fill ceramic balls and catalyst.

[0015] The feed gas enters the coiled tube reactor from the tubular reactor / heat exchanger, and the product gas exits from the product gas outlet through the tubular reactor / heat exchanger; the heat transfer medium enters the coiled tube reactor through the heat transfer medium inlet for heat exchange and exits from the heat transfer medium outlet.

[0016] The segmented temperature-controlled methanation reactor provided in the first aspect of this application combines a coiled-tube reactor with a tubular heat exchanger / reactor. Combined with the internal structural design of the outer shell and the structural arrangement of the central outer tube and inner shell, the reactor is configured such that the feed gas enters the coiled-tube reactor from the tubular reactor / heat exchanger, the product gas exits from the product gas outlet through the tubular reactor / heat exchanger, and the heat transfer medium enters the coiled-tube reactor through the heat transfer medium inlet for heat exchange and exits from the heat transfer medium outlet. This rational flow of gas and heat transfer medium in the tube and shell sides allows for heat exchange between the product gas and feed gas within the tubular reactor / heat exchanger, achieving self-heating of the feed gas and cooling of the product gas. Temperature control is simple, and it eliminates the need for an inlet heater, outlet cooler, or inlet / outlet heat exchanger, shortening the process flow. Furthermore, since the coiled-tube reactor and the tubular heat exchanger / reactor are combined, they can be disassembled during catalyst loading and then reassembled, reducing the difficulty of catalyst loading. Furthermore, depending on actual needs, different catalyst packing structures can be used to achieve chemical reactions with different characteristics along the gas flow direction in the reactor, further optimizing the process and making the reactor suitable for more application scenarios. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a segmented temperature-controlled methanation reactor provided in one embodiment of this application;

[0019] Figure 2 This is a schematic diagram of the internal loading of a tubular reactor / heat exchanger provided in one embodiment of this application;

[0020] Figure 3 This is a schematic diagram of the internal loading of a tubular reactor / heat exchanger provided in another embodiment of this application;

[0021] Figure 4 This is a schematic diagram of the internal loading of a tubular reactor / heat exchanger provided in another embodiment of this application;

[0022] In the diagram: 1-outer shell, 101-product gas outlet, 102-top cover, 103-outer cylinder, 104-raw material gas inlet, 105-heat transfer medium inlet, 106-end, 107-heat transfer medium outlet;

[0023] 2-Tube-and-shell reactor / heat exchanger, 201-Tube sheet, 202-Gasket, 203-Outer wall of tube-and-shell reactor / heat exchanger, 204-Guide tube, 205-Central outer tube, 206-First heat exchange tube, 207-Inner cylinder opening, 208-Gas collecting plate on the tube side, 209-Flange;

[0024] 3-Wound tube reactor, 301-Annular manifold, 302-Connecting pipe, 303-Second heat exchange tube, 304-Central inner tube, 305-Outer wall of wound tube reactor, 306-Gas distribution orifice plate;

[0025] N-ceramic balls, M1, M2, M3-methanation catalysts, C1-conversion catalysts. Detailed Implementation

[0026] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0027] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0028] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0029] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0030] like Figure 1 As shown, the segmented temperature-controlled methanation reactor provided in this application embodiment includes...

[0031] The outer casing 1 has a raw material gas inlet 104 and a heat transfer medium inlet 105 on its side wall, a product gas outlet 101 on its top, and a heat transfer medium outlet 107 on its bottom.

[0032] The tubular reactor / heat exchanger 2 is installed inside the outer shell 1, and its top is connected to the product gas outlet 101;

[0033] The coiled reactor 3 is installed inside the outer shell 1, and its top is connected and communicates with the bottom of the tubular reactor / heat exchanger 2;

[0034] The inner shell is formed by axially connecting the outer wall 203 of the tubular reactor / heat exchanger and the outer wall 305 of the coiled reactor. A sealing annular gap is formed between the outer shell 1 and the inner shell. The outer side of the sealing annular gap is connected to the raw gas inlet 104, and the inner side is connected to the inside of the tubular reactor / heat exchanger 2 through the inner cylinder opening 207 on the outer wall 203 of the tubular reactor / heat exchanger.

[0035] The central outer tube 205 is installed inside the tubular reactor / heat exchanger 2 and extends axially to the lower part of the coiled reactor 3.

[0036] A heat transfer medium channel is used to connect the heat transfer medium inlet 105 and the heat transfer medium outlet 107.

[0037] Among them, the shell side of the coiled reactor 3 is used to fill ceramic balls and catalyst, and the tube side of the tubular reactor / heat exchanger 2 is used to fill ceramic balls or to fill ceramic balls and catalyst.

[0038] The raw material gas enters the coiled tube reactor 3 from the tubular reactor / heat exchanger 2, and the product gas is discharged from the product gas outlet 101 through the tubular reactor / heat exchanger 2; the heat transfer medium enters the coiled tube reactor 3 through the heat transfer medium inlet 105 for heat exchange and is discharged from the heat transfer medium outlet 107.

[0039] In application, the outer casing 1 includes an outer cylinder 103, a sealing head 106 for sealing the bottom of the outer cylinder 103, and a top cover 102 for sealing the top of the outer cylinder 103. The sealing head 106 has a hemispherical structure, and the top cover 102 has a product gas outlet 101 at its center. The raw material gas inlet 104 and the heat transfer medium inlet 105 are both located on the outer cylinder 103 and at its lower part.

[0040] In application, the inner shell is a cylindrical structure formed by the axially tight connection of the outer wall 203 of the tubular reactor / heat exchanger and the outer wall 305 of the coiled-tube reactor. The bottom of the inner shell has an outward-facing annular flange, the outer edge of which is sealed to the inner wall of the outer cylinder 103. The top of the inner shell is sealed by the tube sheet 201 of the tubular reactor / heat exchanger 2, thus forming a sealing annular gap between the inner shell and the outer cylinder 103 of the outer shell 1. The tubular reactor / heat exchanger 2 and the coiled-tube reactor 3 are axially tightly connected by a flange 209. When it is necessary to fill the coiled-tube reactor 3 with catalyst and ceramic balls, the tubular reactor / heat exchanger 2 can be removed by disassembling the flange 209, thus forming an open cavity at the top of the coiled-tube reactor 3, which facilitates rapid filling of the interior. After the inside of the coiled reactor 3 is filled, the tubular reactor / heat exchanger 2 is connected to the coiled reactor 3 through flange 209, and the tube sheet 201 is removed to fill the tubular reactor / heat exchanger 2.

[0041] In this application, there are two openings 207 in the inner cylinder. The raw material gas enters the sealing annular gap through the raw material gas inlet 104, and then enters the interior of the tubular reactor / heat exchanger 2 through the inner cylinder opening 207 on the outer wall 203 of the tubular reactor / heat exchanger. It then enters the interior of the central outer tube 205 through the first gas distribution hole on the central outer tube 205, and follows the central outer tube 205 into the lower part of the coiled reactor 3. The raw material gas flows from bottom to top in the shell side of the coiled reactor 3, exchanging heat with the heat transfer medium in the tube side of the coiled reactor 3, and reacting under the action of the catalyst packed in the shell side of the coiled reactor 3. Finally, the unreacted gas or the high-temperature product gas after the reaction rises into the tube side of the tubular reactor / heat exchanger 2, exchanges heat with the low-temperature raw material gas that has just entered the shell side of the tubular reactor / heat exchanger 2, and is discharged through the product gas outlet 101.

[0042] This embodiment combines a coiled-tube reactor with a tubular heat exchanger / reactor, and incorporates an internal structural design for the outer shell, along with a central outer tube and inner shell. The configuration allows the feed gas to enter the coiled-tube reactor from the tubular reactor / heat exchanger, while the product gas exits through the tubular reactor / heat exchanger. The heat transfer medium enters the coiled-tube reactor through the heat transfer medium inlet for heat exchange and exits through the heat transfer medium outlet. This rational flow of gas and heat transfer medium between the tube and shell sides enables heat exchange between the product gas and feed gas within the tubular reactor / heat exchanger, achieving self-heating of the feed gas and cooling of the product gas. Temperature control is simple, and inlet heaters, outlet coolers, or inlet / outlet heat exchangers are eliminated, shortening the process flow. Furthermore, since the coiled-tube reactor and the tubular heat exchanger / reactor are modular components, they can be disassembled during catalyst loading and reassembled, reducing the difficulty of catalyst loading. Furthermore, depending on actual needs, different catalyst packing structures can be used to achieve chemical reactions with different characteristics along the gas flow direction in the reactor, further optimizing the process and making the reactor suitable for more application scenarios.

[0043] In one embodiment, the tubular reactor / heat exchanger 2 further includes a tube sheet 201, a first heat exchange tube 206, and a tube-side gas collecting plate 208 located within the outer wall 203 of the tubular reactor / heat exchanger. The tube sheet 201 is disposed at the top, and the tube-side gas collecting plate 208 is disposed at the bottom. The outer edges of the tube sheet 201 and the tube-side gas collecting plate 208 are respectively sealed and connected to the outer shell 1 and the inner wall of the tubular reactor / heat exchanger 2. One end of the first heat exchange tube 206 passes through the tube sheet 201 and communicates with the product gas outlet 101, and the other end passes through the tube-side gas collecting plate 208 and communicates with the top of the coiled reactor 3. A central outer tube 205 is disposed inside the first heat exchange tube 206 and communicates with the inner cylinder opening 207.

[0044] In the application, the tube sheet 201 is located at the top, and a gasket 202 is installed between it and the outer cylinder 103. Its function is to support and fix the first heat exchange tube 206 and ensure good sealing between the outside of the first heat exchange tube 206 and the product gas outlet 101. The tube-side gas collecting plate 208 is located at the bottom and is used to collect the rising gas from the coiled reactor 3 and guide the gas flow to the shell-and-tube reactor / heat exchanger 2. The outer edges of both the tube sheet 201 and the tube-side gas collecting plate 208 are sealed to the outer shell 1 and the inner wall of the shell-and-tube reactor / heat exchanger 2 respectively by welding or flange connection, ensuring the closed and controllable nature of the internal fluid path.

[0045] Furthermore, for ease of maintenance and catalyst loading, the tubular reactor / heat exchanger 2 and the wound-tube reactor 3 are axially tightly connected via flange 209. When it is necessary to load catalyst and ceramic balls into the wound-tube reactor 3, the tubular reactor / heat exchanger 2 can be removed by disassembling flange 209, thus forming an open cavity for convenient and rapid loading. After loading, the two parts are reconnected via flange 209, and the tubular reactor / heat exchanger 2 is loaded by removing tube sheet 201. This design not only improves the maintainability of the equipment but also simplifies the catalyst replacement process and reduces downtime.

[0046] In one embodiment, the top of the central outer tube 205 is sealed, and the tube wall of the central outer tube 205 is provided with a first gas distribution hole that connects the inside and outside of the tube wall evenly along the radial direction.

[0047] In this application, a sealing design is employed at the top of the central outer tube 205 to prevent gas leakage and ensure safe operation. The central outer tube 205 has radially uniformly arranged first gas distribution holes connecting the inside and outside of the tube wall. These distribution holes not only ensure that the gas is evenly distributed around the central outer tube 205, increasing the opportunity for gas to contact the heat exchange surface, but also improve heat exchange efficiency. Simultaneously, the uniform gas distribution helps reduce the generation of localized hot spots, extending the equipment's service life. The size and spacing of the first gas distribution holes are precisely calculated to ensure optimal gas flow characteristics and heat transfer effects. In one embodiment, the tubular reactor / heat exchanger 2 further includes a guide tube 204, which is sleeved outside the first heat exchange tube 206. The bottom of the guide tube 204 is connected to the tube-side gas collecting plate 208, and a gap exists between the top of the guide tube 204 and the tube sheet 201 for the passage of raw material gas.

[0048] In application, the guide tube 204 guides the feed gas to flow along the intended path, ensuring that the gas is sufficiently preheated before entering the reaction zone. Furthermore, the guide tube 204 protects the first heat exchange tube 206 from damage caused by direct contact with the high-temperature gas. The gap between the guide tube 204 and the first heat exchange tube 206 is designed to an appropriate width, ensuring smooth gas flow without affecting heat exchange efficiency. The gap between the top of the guide tube 204 and the tube sheet 201 is also optimized to ensure that the gas is adequately preheated before entering the reaction zone, further improving the gas conversion rate under reaction conditions.

[0049] In one embodiment, the coiled reactor 3 further includes an annular manifold 301, a connecting pipe 302, a second heat exchange pipe 303, and a central inner pipe 304 located within the outer wall 305 of the coiled reactor. An annular manifold 301 is provided at the upper and lower parts of the coiled reactor 3, surrounding the central outer pipe 205. The central inner pipe 304 is nested within the central outer pipe 205. The upper annular manifold 301 is connected to the upper part of the central inner pipe 304 through the connecting pipe 302, and the lower annular manifold 301 is connected to the heat transfer medium inlet 105. The upper and lower annular manifolds 301 are connected through the second heat exchange pipe 303. The bottom of the central inner pipe 304 extends and protrudes from the bottom of the outer shell 1. A heat transfer medium channel is formed between the annular manifold 301, the connecting pipe 302, the second heat exchange pipe 303, and the central inner pipe 304. A heat transfer medium outlet 107 is formed at the bottom of the central inner pipe 304.

[0050] In application, the design of the annular manifold 301 allows the heat transfer medium to collect inside the vessel, unlike the traditional design where it collects in the tube sheet and extends outside. This improves upon the shortcomings of traditional manifold methods, such as messy manifold sections that interfere with catalyst loading. The rational arrangement of the connecting pipe 302 and the second heat exchange pipe 303 ensures the uniform distribution of the heat transfer medium, avoiding local overheating. The bottom of the central inner tube 304 extends to the outside of the outer shell 1, allowing the heat transfer medium to be discharged from the system more conveniently. It also helps to monitor the status of the heat transfer medium, ensuring stable system operation.

[0051] In one embodiment, the coiled reactor 3 further includes a gas distribution orifice plate 306. The gas distribution orifice plate 306 is tightly fitted with the shaft hole at the lower part of the central outer tube 205. The outer edge of the gas distribution orifice plate 306 is sealed to the inner wall of the outer shell 1. The gas distribution orifice plate 306 is uniformly provided with axially penetrating second gas distribution holes. The bottom of the central outer tube 205 is provided with an axial opening below the gas distribution orifice plate 306.

[0052] In application, the presence of the gas distribution orifice plate 306 ensures uniform gas distribution across the entire cross-section, improving the contact between the feed gas and the catalyst, thereby enhancing reaction efficiency and product quality. The second gas distribution holes on the gas distribution orifice plate 306 are meticulously designed, with hole size and spacing taking into account factors such as gas flow rate and pressure drop to achieve optimal gas dispersion. Furthermore, the tight fit between the gas distribution orifice plate 306 and the central outer tube 205 ensures structural stability, preventing displacement or damage due to gas impact, thus extending the equipment's service life.

[0053] In one embodiment, the bottom sidewall of the central outer tube 205 is provided with a third gas distribution hole uniformly in the radial direction.

[0054] In application, the gas distribution orifice plate 306 can be omitted. In this case, the bottom of the central outer tube 205 is sealed to the axial opening below the central inner tube 304. Instead, a third gas distribution orifice is uniformly arranged radially on the bottom sidewall, ensuring that the gas can flow evenly into the shell side of the coiled tube reactor 3, thereby improving the gas mixing effect and making the reaction more uniform. At the same time, these distribution orifices also facilitate the uniform distribution of heat and prevent local overheating. The size and spacing of the third gas distribution orifice are optimized to ensure that the gas can smoothly enter the coiled tube reactor 3 without causing excessive pressure loss. In addition, the design of these distribution orifices also takes into account the changes in gas flow under different operating conditions to adapt to the needs of various working conditions. In this way, the central outer tube 205 not only plays the role of gas distribution but also enhances the overall structural stability and durability.

[0055] In application, when the gas distribution orifice plate 306 is provided, the filling area of ​​the coiled reactor 3 is the area from above the gas distribution orifice plate 306 to the tube-side gas collecting plate 208. When the gas distribution orifice plate 306 is not provided, the filling area of ​​the coiled reactor 3 is the entire area below the tube-side gas collecting plate 208.

[0056] In one embodiment, the tubular reactor / heat exchanger 2 is a tubular reactor or a tubular heat exchanger;

[0057] When the tubular reactor / heat exchanger 2 is a tubular reactor, the tube side of the tubular reactor / heat exchanger 2 is used to fill ceramic balls and catalyst.

[0058] When the tubular reactor / heat exchanger 2 is a tubular heat exchanger, the tube side of the tubular reactor / heat exchanger 2 is used to fill ceramic balls.

[0059] In application, the tubular reactor / heat exchanger 2 can be either a tubular reactor or a tubular heat exchanger, depending on the material to be packed inside the first heat exchange tube. When the material is ceramic balls and catalyst, the tubular reactor / heat exchanger 2 is a tubular reactor. When the material is only ceramic balls and does not contain catalyst, the tubular reactor / heat exchanger 2 is a tubular heat exchanger.

[0060] This flexibility in the embodiments of this application allows the reactor's function to be adjusted according to different chemical reaction requirements to meet diverse process needs. For example, in methanation reactions, a tubular reactor configuration can be selected if a higher single-pass conversion rate is required; while in certain preheating or cooling processes, a tubular heat exchanger configuration can be selected. Furthermore, selecting different packing materials can optimize reaction conditions; for example, using specific types of catalysts can improve reaction rates and product selectivity, while ceramic balls provide additional surface area, promoting the dispersion and mixing of reactants. By flexibly configuring tubular reactors / heat exchangers, the performance and economic efficiency of the entire system can be significantly improved.

[0061] In one embodiment, when the tube side of the tubular reactor / heat exchanger 2 is filled with ceramic balls, the catalyst filled in the shell side of the coiled reactor 3 is a first methanation catalyst or a third methanation catalyst. When the catalyst filled in the shell side of the coiled reactor 3 is a third methanation catalyst, a shift catalyst is filled between the outer wall 203 of the tubular reactor / heat exchanger and the guide tube 204.

[0062] When the tube side of the tubular reactor / heat exchanger 2 is used to fill ceramic balls and catalyst, the catalyst filled in the shell side of the coiled reactor 3 is the first methanation catalyst, and the catalyst filled in the tube side of the tubular reactor / heat exchanger 2 is the second methanation catalyst.

[0063] In applications, when the tube side of the tubular reactor / heat exchanger 2 is filled with ceramic balls and catalyst, the ceramic balls and catalyst are alternately distributed along the axial direction.

[0064] When a shift catalyst is filled between the outer wall 203 of the tubular reactor / heat exchanger and the guide tube 204, the ceramic balls and the catalyst are alternately distributed radially, and the ceramic ball layer and the catalyst layer are separated by a cylindrical partition net.

[0065] In the shell side of the coiled reactor 3, ceramic balls and catalyst are alternately distributed along the axial direction.

[0066] This alternating distribution effectively increases the reaction rate. The ceramic balls provide additional surface area, promoting reactant dispersion, while the catalyst layer catalyzes the reaction more effectively. The use of a separator ensures that different materials do not mix, preserving their individual properties and activities, thereby improving overall reaction efficiency and product quality. This catalyst and ceramic ball loading scheme achieves an optimal reaction environment, improving production efficiency and product quality.

[0067] Example 1

[0068] This application uses a shell-and-tube reactor / heat exchanger 2 as an example, where the tube side of the shell-and-tube heat exchanger is filled only with ceramic balls, and the shell side of the coiled-tube reactor 3 is filled with ceramic balls and a first methanation catalyst. This application is applicable to strongly exothermic reaction systems such as methanation, where the feed gas temperature is below 200°C and the carbon concentration (CO+CO2) is 3-10%, relying on the high-temperature product gas at the outlet of the coiled-tube reactor 3 to preheat the feed gas.

[0069] like Figure 2 As shown, the shell side of the coiled-tube reactor 3 is filled with ceramic balls and a first methanation catalyst, namely methanation catalyst M1 (specifically, a 3mm*3mm cylindrical catalyst with a nickel oxide loading of 15-25 wt%). The ceramic balls and methanation catalyst M1 are alternately distributed axially; for example, the top and bottom layers can be ceramic balls, while the middle layer is methanation catalyst M1. For reactors with a gas distribution orifice plate 306, the filling range is from the gas distribution orifice plate 306 to the tube-side gas collecting plate 208. For reactors without a gas distribution orifice plate 306, the filling range is the entire area below the tube-side gas collecting plate 208. The first heat exchange tube 206 of the shell-and-tube heat exchanger is only filled with ceramic balls, specifically between the tube-side gas collecting plate 208 and the tube sheet 201.

[0070] The feed gas enters the sealed annular gap through the feed gas inlet 104, enters the shell side of the shell-and-tube heat exchanger through the inner cylinder opening 207, passes radially through the first heat exchange tube 206, and then enters the interior of the central outer tube 205 through the first gas distribution hole on the wall of the central outer tube 205. It then enters axially downwards below the gas distribution orifice plate 306 (for reactors without a gas distribution orifice plate 306, it directly enters the bottom region of the coiled-tube reactor 3 through the third gas distribution hole at the bottom of the central outer tube 205). From the bottom, it enters the shell side of the coiled-tube reactor 3 and reacts with the catalyst. The resulting product gas enters the tube side of the shell-and-tube heat exchanger to preheat the feed gas in the shell side. The product gas exits the reactor from the reactor outlet 101.

[0071] Saturated water at a pressure of 3.5 MPa enters the tube side of the coiled-tube reactor 3 through the heat transfer medium inlet 105, carrying away the reaction heat in the shell side of the coiled-tube reactor 3. The saturated water sequentially passes through the annular manifold 301, the second heat exchange tube 303, the connecting pipe 302, and the central inner tube 304, and finally flows out of the reactor from the heat transfer medium outlet 107.

[0072] Example 2

[0073] This application uses a tubular reactor / heat exchanger 2 as an example, with ceramic balls and a second methanation catalyst packed in the tubes of the tubular reactor, and ceramic balls and a first methanation catalyst packed in the shell side of the coiled-tube reactor 3. This application is applicable to strongly exothermic reaction systems such as methanation, where the feed gas temperature is below 150°C and the carbon concentration is 10-15%. Due to the high carbon concentration in the feed gas, the coiled-tube reactor 3 cannot completely convert the carbon, requiring further reaction in the tubular reactor.

[0074] like Figure 3 As shown, the shell side of the lower tubular reactor 3 is filled with ceramic balls, specifically the first methanation catalyst, namely methanation catalyst M1 (a 3mm*3mm cylindrical catalyst with a nickel oxide loading of 15-25 wt%). The ceramic balls and methanation catalyst M1 are alternately distributed axially; for example, the top and bottom layers can be ceramic balls, while the middle layer is methanation catalyst M1. For reactors with a gas distribution orifice plate 306, the filling range is between the gas distribution orifice plate 306 and the tube-side gas collecting plate 208. For reactors without a gas distribution orifice plate 306, the filling range is the entire area below the tube-side gas collecting plate 208. The upper tubular reactor has ceramic balls and a second methanation catalyst, namely methanation catalyst M2 (a 3mm*3mm cylindrical catalyst with a nickel oxide loading of 5-15 wt%), in the tube side of the first heat exchange tube 206, specifically between the tube-side gas collecting plate 208 and the tube sheet 201.

[0075] The flow direction of the raw material gas and product gas is the same as in Example 1. The difference is that the raw material gas that has not been fully reacted in the shell side of the coiled reactor 3 enters the tube side of the tubular reactor through the opening of the tube side gas collecting plate 208 and the first heat exchange tube for further reaction. This not only effectively improves the single-pass conversion rate, but also further preheats the cold raw material gas through the reaction heat of the tubular reactor.

[0076] Example 3

[0077] This application uses a shell-and-tube reactor / heat exchanger 2 as an example, where only ceramic balls are filled in the tubes, and a shift catalyst is filled between the outer wall 203 and the guide tube 204 of the shell-and-tube reactor / heat exchanger. The shell side of the coiled-tube reactor 3 is filled with ceramic balls and a third methanation catalyst. This application is applicable to continuous multi-stage reactions, where the feed gas for a later stage reaction is the product gas for a previous stage reaction. For example, in a coal-to-methanol process, after the hydrogen-to-carbon ratio of water gas is adjusted through a shift reaction, its product gas is purified and used as the feed gas for methanol synthesis.

[0078] like Figure 4 As shown, the shell side of the coiled-tube reactor 3 is filled with ceramic balls and a third methanation catalyst, namely, a sulfur-resistant methanation catalyst M3 (specifically, a 3mm*3mm cylindrical catalyst with molybdenum oxide as the active component). The ceramic balls and methanation catalyst M3 are alternately distributed along the axial direction; for example, the top and bottom layers can be ceramic balls, while the middle layer is methanation catalyst M3. For reactors with a gas distribution orifice plate 306, the filling range is from the gas distribution orifice plate 306 to the tube-side gas collecting plate 208. For reactors without a gas distribution orifice plate 306, the filling range is the entire area below the tube-side gas collecting plate 208. The first heat exchange tube 206 of the upper tubular heat exchanger of the reactor is only filled with ceramic balls, specifically between the tube-side gas collecting plate 208 and the tube sheet 201. The area between the outer wall 203 of the tubular reactor / heat exchanger and the guide tube 204 is filled radially with one layer of ceramic balls, one layer of shift catalyst C1 (specifically a 3mm*4mm cylindrical catalyst, a cobalt-molybdenum-based sulfur-resistant shift catalyst), and one layer of ceramic balls, with each layer separated by a cylindrical partition net.

[0079] The feed gas composition is 25% carbon, 15% hydrogen, and 60% water, at a temperature of 200℃. The feed gas enters the sealed annular gap through the feed gas inlet 104, enters the shell side of the tube heat exchanger through the inner cylinder opening 207, passes radially through the catalyst bed and undergoes a shift reaction, finely adjusting the hydrogen-to-carbon ratio. Subsequently, the product gas after the reaction enters the coiled tube reactor 3 to undergo a methanation reaction.

[0080] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A segmented temperature-controlled methanation reactor, characterized in that, include The outer shell (1) has a raw material gas inlet (104) and a heat transfer medium inlet (105) on its side wall, a product gas outlet (101) on its top, and a heat transfer medium outlet (107) on its bottom. A tubular reactor / heat exchanger (2) is installed inside the outer shell (1), with the top of its tubes connected to the product gas outlet (101); A coiled reactor (3) is installed inside the outer shell (1), with its shell side top connected and communicating with the tube side bottom of the tubular reactor / heat exchanger (2); The inner shell is formed by axially connecting the outer wall (203) of the tubular reactor / heat exchanger and the outer wall (305) of the coiled reactor. A sealing annular gap is formed between the outer shell (1) and the inner shell. The outer side of the sealing annular gap is connected to the raw gas inlet (104), and the inner side is connected to the inside of the tubular reactor / heat exchanger (2) through the inner cylinder opening (207) on the outer wall (203). The central outer tube (205) is installed inside the tubular reactor / heat exchanger (2) and extends axially to the lower part of the coiled reactor (3); A heat transfer medium channel is provided for connecting the heat transfer medium inlet (105) and the heat transfer medium outlet (107); The shell side of the coiled reactor (3) is used to fill ceramic balls and catalyst, and the tube side of the tubular reactor / heat exchanger (2) is used to fill ceramic balls or to fill ceramic balls and catalyst. The raw material gas enters the coiled reactor (3) from the tubular reactor / heat exchanger (2), and the product gas is discharged from the product gas outlet (101) through the tubular reactor / heat exchanger (2); the heat transfer medium enters the coiled reactor (3) through the heat transfer medium inlet (105) for heat exchange and is discharged from the heat transfer medium outlet (107).

2. The segmented temperature-controlled methanation reactor as described in claim 1, characterized in that, The tubular reactor / heat exchanger (2) further includes a tube sheet (201), a first heat exchange tube (206), and a tube-side gas collecting plate (208) located inside the outer wall (203) of the tubular reactor / heat exchanger. The tube sheet (201) is located at the top, and the tube-side gas collecting plate (208) is located at the bottom. The outer edges of the tube sheet (201) and the tube-side gas collecting plate (208) are respectively sealed and connected to the outer shell (1) and the inner wall of the tubular reactor / heat exchanger (2). One end of the first heat exchange tube (206) passes through the tube sheet (201) and is connected to the product gas outlet (101). The other end passes through the tube-side gas collecting plate (208) and is connected to the top of the coiled reactor (3). The central outer tube (205) is located inside the first heat exchange tube (206) and is connected to the inner cylinder opening (207).

3. The segmented temperature-controlled methanation reactor as described in claim 2, characterized in that, The top of the central outer tube (205) is sealed, and the tube wall of the central outer tube (205) is provided with a first gas distribution hole that connects the inside and outside of the tube wall in a radially uniform manner.

4. The segmented temperature-controlled methanation reactor as described in claim 2, characterized in that, The tubular reactor / heat exchanger (2) further includes a guide tube (204), which is sleeved outside the first heat exchange tube (206). The bottom of the guide tube (204) is connected to the tube side gas collecting plate (208), and there is a gap between the top of the guide tube (204) and the tube sheet (201) for the raw material gas to pass through.

5. The segmented temperature-controlled methanation reactor as described in claim 1, characterized in that, The coiled reactor (3) further includes an annular manifold (301), a connecting pipe (302), a second heat exchange tube (303), and a central inner tube (304) located within the outer wall (305) of the coiled reactor. An annular manifold (301) is provided at the upper and lower parts of the central outer tube (205) within the coiled reactor (3). The central inner tube (304) is nested within the central outer tube (205). The annular manifold (301) at the upper part is connected to the upper part of the central inner tube (304) via a connecting pipe. 302) The lower annular manifold (301) is connected to the heat transfer medium inlet (105). The upper and lower annular manifolds (301) are connected by a second heat exchange tube (303). The bottom of the central inner tube (304) extends and protrudes from the bottom of the outer shell (1). A heat transfer medium channel is formed between the annular manifold (301), the connecting tube (302), the second heat exchange tube (303), and the central inner tube (304). The bottom of the central inner tube (304) forms the heat transfer medium outlet (107).

6. The segmented temperature-controlled methanation reactor as described in claim 1, characterized in that, The coiled reactor (3) further includes a gas distribution perforated plate (306), which is tightly fitted with the shaft hole of the gas distribution perforated plate (306) at the lower part of the central outer tube (205). The outer edge of the gas distribution perforated plate (306) is sealed to the inner wall of the outer shell (1). The gas distribution perforated plate (306) is uniformly provided with axially penetrating second gas distribution holes. The bottom of the central outer tube (205) is provided with an axial opening below the gas distribution perforated plate (306).

7. The segmented temperature-controlled methanation reactor as described in claim 1, characterized in that, The bottom sidewall of the central outer tube (205) is uniformly provided with a third gas distribution hole along the radial direction.

8. The segmented temperature-controlled methanation reactor as described in claim 1, characterized in that, The tubular reactor / heat exchanger (2) is a tubular reactor or a tubular heat exchanger. When the tubular reactor / heat exchanger (2) is the tubular reactor, the shell side of the tubular reactor / heat exchanger (2) is used to fill ceramic balls and catalyst; When the tubular reactor / heat exchanger (2) is the tubular heat exchanger, the shell side of the tubular reactor / heat exchanger (2) is used to fill ceramic balls.

9. The segmented temperature-controlled methanation reactor as described in claim 4, characterized in that, When the tube side of the tubular reactor / heat exchanger (2) is filled with ceramic balls, the catalyst filled in the shell side of the coiled reactor (3) is a first methanation catalyst or a third methanation catalyst. When the catalyst filled in the shell side of the coiled reactor (3) is a third methanation catalyst, a shift catalyst is filled between the outer wall (203) of the tubular reactor / heat exchanger and the guide tube (204). When the tube side of the tubular reactor / heat exchanger (2) is filled with ceramic balls and catalyst, the catalyst filled in the shell side of the coiled reactor (3) is a first methanation catalyst, and the catalyst filled in the tube side of the tubular reactor / heat exchanger (2) is a second methanation catalyst.

10. The segmented temperature-controlled methanation reactor as described in claim 9, characterized in that, When the tube side of the tubular reactor / heat exchanger (2) is filled with ceramic balls and catalyst, the ceramic balls and catalyst are alternately distributed along the axial direction; When the outer wall (203) of the tubular reactor / heat exchanger and the guide tube (204) are filled with a shift catalyst, the ceramic balls and the catalyst are alternately distributed radially, and the ceramic ball layer and the catalyst layer are separated by a cylindrical partition net. The ceramic balls and catalyst packed in the shell side of the coiled reactor (3) are alternately distributed along the axial direction.

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