Fixed bed reactor and tetrahydrofuran production device
By introducing a central tube and annular channel design into the fixed-bed reactor, the problems of high catalyst bed pressure drop and low conversion rate were solved, achieving more efficient tetrahydrofuran production and reducing equipment costs and operating expenses.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-13
- Publication Date
- 2026-03-17
AI Technical Summary
Existing fixed-bed reactors have high catalyst bed pressure drop and low reaction conversion rates when producing tetrahydrofuran. They also require the recovery of large amounts of unreacted 1,4-butanediol, and have high equipment investment and operating costs.
Design a fixed-bed reactor, including a central tube, a catalyst bed, a bottom plate, and a feed distribution section. The central tube has radial openings on its sidewalls, and there is an annular channel between the catalyst bed and the inner wall of the reactor cylinder. Gaseous and liquid products are processed separately, and the annular channel provides additional flow space to reduce the pressure drop of the catalyst bed.
It improved the raw material conversion rate, reduced the catalyst bed pressure drop, stabilized the reaction conditions, reduced product quality fluctuations, and lowered equipment investment and operating costs.
Smart Images
Figure CN223996040U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of chemical reactor technology, and in particular to a fixed-bed reactor and a tetrahydrofuran production apparatus. Background Technology
[0002] Tetrahydrofuran (THF), a highly polar solvent, possesses strong dissolving power, capable of dissolving numerous organic substances and playing an irreplaceable role in organic synthesis. It is also a key raw material for the preparation of various polymers such as polycarbonates, polyether esters, polyolefins, and polyurethanes, and holds an important position in the pharmaceutical industry, used to prepare various drug components. Furthermore, THF is widely used as an additive in coatings, plastics, and rubber products, and even as a component of electrolytes in battery manufacturing.
[0003] Among the relevant technologies, the processes for producing THF include the furfural method, the direct hydrogenation method of maleic anhydride, and the dehydration method of 1,4-butane-1,4-diol (BDO). The furfural method has been gradually phased out due to its complex process and serious pollution. The direct hydrogenation method of maleic anhydride has high requirements for equipment due to high pressure reaction and acidic raw materials, resulting in high fixed investment and operating costs. The BDO dehydration method has become the main method due to its low reaction temperature, low pressure, and high yield. The fixed-bed reactor commonly used in this method has a high pressure drop in the catalyst bed and a low reaction conversion rate when producing THF, requiring the recovery of a large amount of unreacted BDO. Utility Model Content
[0004] This application is made in view of the above-mentioned problems. This application provides a fixed-bed reactor and a tetrahydrofuran production apparatus.
[0005] According to one aspect of this application, a fixed-bed reactor is provided, comprising:
[0006] The reactor shell includes a central tube, a catalyst bed, a bottom plate, and a raw material distribution section disposed within the reactor shell. The central tube is located at the axial center of the reactor shell, and its sidewalls have multiple radial openings distributed axially. The catalyst bed is located between the central tube and the inner wall of the reactor shell. The bottom plate is located at the end of the central tube facing the bottom of the reactor shell and is fixedly connected to the inner wall of the reactor shell. The bottom end of the reactor shell has a feed channel, and the raw material distribution section is located at the end of the feed channel near the central tube. The top end of the reactor shell has a gaseous product channel. An annular channel exists between the catalyst bed and the inner wall of the reactor shell. A fluid channel is formed on the sidewall of the reactor shell, and the fluid channel communicates with the annular channel.
[0007] Compared with the prior art, the fixed-bed reactor provided in this application includes a reactor shell and a central tube, a catalyst bed, a bottom plate, and a raw material distribution section disposed within the reactor shell. The central tube is located at the axial center of the reactor shell, the catalyst bed is located between the central tube and the inner wall of the reactor shell, and the bottom plate is located at the end of the central tube facing the bottom of the reactor shell and is fixedly connected to the inner wall of the reactor shell. The bottom end of the reactor shell has a feed channel, and the raw material distribution section is located at the end of the feed channel near the central tube. Therefore, the raw material can enter the reactor shell through the feed channel at the bottom end of the reactor shell. Under the action of the raw material distribution section, the raw material can be uniformly and stably fed into the central tube, which helps maintain the stability of the reaction process, allowing the reaction to proceed under relatively stable conditions. This reduces changes in parameters such as reaction temperature and pressure caused by feed fluctuations, which is beneficial for improving the stability of product quality and reducing product quality fluctuations. Because the sidewall of the central tube has multiple radial openings distributed along the axial direction, the raw material can enter the catalyst bed relatively smoothly through these openings. Under the preset temperature and pressure, the raw material continuously contacts and reacts with the catalyst bed in the radial direction, gradually transforming into products. This avoids the increase in pressure drop caused by the narrow or blocked flow path of the raw material in the catalyst bed, which is beneficial to reducing the pressure drop of the catalyst bed.
[0008] Based on this, the reactor shell has a gaseous product channel at the top and an annular channel between the catalyst bed and the inner wall of the reactor shell. Fluid channels are formed on the side walls of the reactor shell, communicating with the annular channel. Therefore, the gaseous products generated by the reaction can flow upwards and exit the reactor shell through the gaseous product channel for post-processing. Liquid products containing impurities that do not participate in the reaction collect along the annular channel into the fluid channel and exit the reactor shell. Similarly, if the gaseous products, after post-processing, produce liquid products including the raw materials, these liquid products can flow into the reactor shell through the fluid channel, contact the catalyst bed, and react. During this process, the generated gaseous products flow upwards and exit the reactor shell through the gaseous product channel, while the generated liquid products containing impurities that do not participate in the reaction collect along the annular channel into the fluid channel and exit the reactor shell. It is evident that the annular channel provides additional flow space for the reacted materials, reducing the flow rate and pressure of a single channel and helping to lower the overall pressure drop of the catalyst bed. Simultaneously, the annular channel makes the fluid distribution across the cross-section of the reactor shell more uniform, avoiding excessive pressure drop caused by localized excessive flow.
[0009] Based on this, the embodiments of this application discharge the liquid product from the reactor shell, remove the components in the liquid product that do not participate in the reaction, and discharge the generated gaseous product from the reactor shell to promote the forward chemical reaction, thereby effectively improving the conversion rate of raw materials while reducing the pressure drop of the catalyst bed.
[0010] According to another aspect of this application, a tetrahydrofuran production apparatus is provided, comprising the aforementioned fixed-bed reactor.
[0011] Compared with the prior art, the beneficial effects of the tetrahydrofuran production apparatus provided in this application are the same as those of the fixed-bed reactor described above, and will not be repeated here.
[0012] It should be understood that both the foregoing general description and the following detailed description are exemplary and intended to provide further illustration of the claimed technology. Attached Figure Description
[0013] The above and other objects, features, and advantages of this application will become more apparent from the more detailed description of the embodiments of this application in conjunction with the accompanying drawings. The accompanying drawings are used to provide a further understanding of the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof. In the accompanying drawings, the same reference numerals generally represent the same components or steps.
[0014] Figure 1 A schematic diagram of the structure of a fixed-bed reactor according to an embodiment of this application is shown;
[0015] Figure 2 A schematic diagram of one possible structure of the catalyst bed according to an embodiment of this application is shown;
[0016] Figure 3 This paper shows another schematic diagram of the catalyst bed structure according to an embodiment of the present application;
[0017] Figure 4 A cross-sectional view of a fixed-bed reactor according to an embodiment of this application is shown.
[0018] Figure label:
[0019] 1-Reactor shell; 101-Feed channel; 102-Gaseous product channel; 103-Annular channel; 104-Fluid channel; 2-Central tube; 3-Catalyst bed; 301-Corrugated support; 302-Catalyst unit; 4-Bottom plate; 5-Raw material distribution section; and 6-Buffer. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of this application more apparent, exemplary embodiments according to this application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein.
[0021] THF, as a highly polar solvent, possesses strong dissolving power, capable of dissolving numerous organic substances and playing an irreplaceable role in the field of organic synthesis. It is also a key raw material for the preparation of various polymers such as polycarbonates, polyether esters, polyolefins, and polyurethanes, and holds an important position in the pharmaceutical industry, being used to prepare various drug components. Furthermore, THF is widely used as an additive in coatings, plastics, and rubber products, and even as a component of electrolytes in battery manufacturing.
[0022] Among related technologies, the processes for producing tetrahydrofuran include the furfural process, the direct hydrogenation of maleic anhydride, and the BDO dehydration process. The furfural process is gradually being phased out due to its complexity and severe pollution. The direct hydrogenation of maleic anhydride requires high-pressure reactions and acidic raw materials, resulting in high equipment requirements, fixed investment, and operating costs. The BDO dehydration process, which involves dehydrating BDO to produce THF under acid catalysis, is the primary method due to its low reaction temperature, low pressure, and high yield. The commonly used reactor for this method is the fixed-bed reactor. A fixed-bed reactor is a reactor filled with solid catalysts or solid reactants to achieve a multiphase reaction process. The reactor is filled with granular solids, stacked into a bed of a certain height or thickness. The bed remains stationary, and the fluid reacts as it passes through. In THF production, this fixed-bed reactor has a high pressure drop and low reaction conversion rate, requiring the recovery of a large amount of unreacted BDO.
[0023] To address the aforementioned issues, this application provides a fixed-bed reactor that not only reduces the pressure drop in the catalyst bed but also effectively improves the conversion rate of the feedstock. Figure 1 A schematic diagram of the structure of a fixed-bed reactor according to an embodiment of this application is shown. Figure 1 As shown, the fixed-bed reactor of this embodiment includes a reactor body 1 and a central tube 2, a catalyst bed 3, a bottom plate 4, and a raw material distribution section 5 disposed within the reactor body 1. The central tube 2 is located at the axial center of the reactor body 1, and the sidewall of the central tube 2 has multiple radial openings distributed along the axial direction. The catalyst bed 3 is located between the central tube 2 and the inner wall of the reactor body 1. The bottom plate 4 is located at one end of the central tube 2 facing the bottom of the reactor body 1 and is fixedly connected to the inner wall of the reactor body 1. The bottom end of the reactor body 1 has a feed channel 101, and the raw material distribution section 5 is located at one end of the feed channel 101 near the central tube 2. The top end of the reactor body 1 has a gaseous product channel 102. An annular channel 103 is provided between the catalyst bed 3 and the inner wall of the reactor body 1. A fluid channel 104 is provided on the sidewall of the reactor body 1, and the fluid channel 104 communicates with the annular channel 103. In this embodiment, the bottom plate 4 ensures that the raw material, after entering the reactor cylinder 1, does not directly enter the catalyst bed 3, but instead enters the central tube 2 and enters the catalyst bed 3 through its radial openings, which helps maintain the stability of the reaction process. It should be understood that... Figure 1The arrow described in the text indicates the axial direction extending from the top of the reactor cylinder to the bottom of the reactor cylinder. For ease of description, this direction is named the 'a' direction.
[0024] In practice, the raw material enters the reactor body 1 through the feed channel 101 at the bottom of the reactor body 1. Under the action of the raw material distribution section 5, the raw material can be uniformly and stably fed into the central tube 2, which helps maintain the stability of the reaction process and allows the reaction to proceed under relatively stable conditions. This reduces changes in parameters such as reaction temperature and pressure caused by feed fluctuations, which is beneficial to improving the stability of product quality and reducing product quality fluctuations. Next, the raw material smoothly enters the catalyst bed 3 through the openings on the central tube 2. Under the preset temperature and pressure, the raw material continuously contacts and reacts with the catalyst bed 3 in the radial direction, gradually transforming into products. This avoids the increase in pressure drop caused by narrow or blocked flow paths in the catalyst bed 3, which helps to reduce the pressure drop of the catalyst bed 3.
[0025] In this process, the gaseous product flows upward and exits the reactor shell 1 through the gaseous product channel 102 for post-processing; the liquid product, containing impurities that do not participate in the reaction, collects along the annular channel 103 into the fluid channel 104 and exits the reactor shell 1. Similarly, if the gaseous product, after post-processing, produces a liquid product including the raw material, it can flow into the reactor shell 1 through the fluid channel 104, contact and react with the catalyst bed 3. In this process, the generated gaseous product flows upward and exits the reactor shell 1 through the gaseous product channel 102, while the generated liquid product, containing impurities that do not participate in the reaction, collects along the annular channel 103 into the fluid channel 104 and exits the reactor shell 1. It is evident that the annular channel 103 provides additional flow space for the reacted material, reducing the flow pressure of a single channel and helping to lower the overall pressure drop of the catalyst bed 3. Simultaneously, the annular channel 103 makes the fluid distribution across the cross-section of the reactor shell 1 more uniform, avoiding increased pressure drop caused by excessive local flow.
[0026] Based on this, the embodiment of this application discharges the liquid product from the reactor cylinder 1, removes the components in the liquid product that do not participate in the reaction, and discharges the generated gaseous product from the reactor cylinder 1, promoting the forward chemical reaction, thereby effectively improving the conversion rate of raw materials while reducing the pressure drop of the catalyst bed 3.
[0027] In practical applications, the gaseous product containing THF generated in the reactor shell can be processed sequentially through a dehydration section and a BDO recovery section. After dehydration, the material can be extracted and distilled in the BDO recovery section to remove residual water. The top of the BDO recovery section yields THF with a water content of less than 100 ppm, while the material at the bottom of the BDO recovery section is recycled back to the fixed-bed reactor. Furthermore, embodiments of this application can also utilize computational fluid dynamics flow field simulation technology to optimize the central tube opening scheme, resulting in a more uniform fluid distribution inside the reactor shell. This effectively improves the mixing condition and mass transfer efficiency of the raw materials, thereby increasing the BDO conversion rate.
[0028] It is understood that, in the embodiments of this application, the central tube can also be set on the support ring of the pallet to provide stable support force and ensure that the axial position of the central tube is fixed. The support method is not limited to this and can be adjusted according to the actual situation.
[0029] In one alternative embodiment, the catalyst bed of this application includes a catalyst support assembly and multiple catalyst units. The catalyst support assembly includes multiple stacked corrugated supports with opposite inclination directions of the corrugations of adjacent corrugated supports. Multiple catalyst units are fixed inside the corrugated supports, so that the flow path of the raw material changes continuously when it passes through the catalyst bed, thereby promoting the uniform distribution of the raw material across the entire cross-section of the catalyst bed, allowing the raw material to have more sufficient contact with the catalyst units, improving reaction efficiency, and greatly saving catalyst usage and investment.
[0030] Figure 2 A schematic diagram of one possible structure of the catalyst bed according to an embodiment of this application is shown. Figure 1 and Figure 2 As shown, in this embodiment, there is a gap between two adjacent corrugated support members 301, and multiple catalyst units 302 are fixed within the gap. This effectively prevents the catalyst units 302 from shifting or shaking during contact with the raw materials, ensuring the relative position of the catalyst in the bed is stable and helping to maintain the stability and consistency of the reaction. Simultaneously, this arrangement allows the raw materials to enter and exit from multiple directions around the catalyst units 302, avoiding localized concentration of the raw materials and promoting a more uniform distribution of the raw materials throughout the entire catalyst bed 3. This allows for sufficient contact between the raw materials and the catalyst, improving reaction efficiency and conversion rate. Furthermore, in this embodiment, the corrugated support members 301 are placed in the reactor cylinder along direction a, which is perpendicular to... Figure 1 The direction of 'a' in the equation is the same.
[0031] Figure 3 A schematic diagram of another structure of the catalyst bed according to an embodiment of this application is shown. Figure 1 and Figure 3As shown, in this embodiment, multiple catalyst units 302 are fixed within the corrugations of the corrugated support 301. The shape and orientation of these corrugations guide the fluid to flow along a specific path, allowing the fluid to be more evenly distributed around each catalyst unit 302 when passing through the catalyst bed 3. This increases the contact area and efficiency between the fluid and the catalyst, thus improving reaction efficiency and conversion rate. Furthermore, in this embodiment, the corrugated support 301 is positioned within the reactor cylinder along direction a, which is parallel to... Figure 1 The direction of 'a' is the same. It should be understood that the shape of the catalyst unit in the embodiments of this application can be spherical or irregularly shaped, or columnar, and can be adjusted according to the actual situation, and is not limited here.
[0032] In practical applications, the packing density of the catalyst unit in the embodiments of this application can be adjusted according to actual needs, and is not limited here.
[0033] In one alternative embodiment, each catalyst unit of this application includes a flexible mesh support and catalyst particles disposed within the flexible mesh support. The flexible mesh support reduces the frequency and intensity of friction between the catalyst particles and the raw materials, thus reducing the likelihood of catalyst particle wear. Furthermore, when fluid passes through the flexible mesh support containing the catalyst particles, the mesh structure guides the fluid to flow more uniformly and orderly over the catalyst particles, reducing the probability of catalyst particle accumulation and blockage due to poor raw material flow.
[0034] For example, the flexible mesh carriers in this application embodiment include metal flexible mesh carriers, ceramic flexible mesh carriers, or polymer flexible mesh carriers. For instance, flexible mesh carriers made of stainless steel or nickel-based alloys. When the flexible mesh carrier is made of stainless steel, it ensures that its structure is not corroded, thereby continuously reducing the probability of catalyst particle wear, accumulation, and blockage. When the flexible mesh carrier is made of nickel-based alloys, it can maintain shape stability at high temperatures, preventing structural deformation caused by thermal expansion and contraction, which would affect the encapsulation effect on catalyst particles. Another example is flexible mesh carriers made of alumina or zirconium oxide. When the flexible mesh carrier is made of alumina, it can maintain the uniformity of the temperature of the entire catalyst bed while reducing the probability of catalyst particle accumulation and blockage, preventing catalyst deactivation or decreased reaction selectivity due to uneven temperature. Yet another example is flexible mesh carriers made of polypropylene or polytetrafluoroethylene. When the flexible mesh support is made of polytetrafluoroethylene, it has excellent chemical stability and an extremely low coefficient of friction, which can effectively prevent the catalyst particles from sticking to the support while reducing the probability of catalyst particle accumulation and blockage.
[0035] Figure 4 A cross-sectional view of a fixed-bed reactor according to an embodiment of this application is shown. Figure 1 and Figure 4 As shown, the fixed-bed reactor of this embodiment includes multiple buffer elements 6, which are evenly distributed around the central tube 2 along the axial direction. When there are three buffer elements, the included angle between two adjacent buffer elements is 120°. These buffer elements 6 spatially divide the catalyst bed 3 into multiple catalytic reaction spaces. Furthermore, when the reaction temperature inside the fixed-bed reactor rises sharply from room temperature to several hundred degrees Celsius, the size of the central tube 2 will increase significantly. The buffer elements 6 can absorb the thermal expansion caused by temperature changes, preventing cracks and leaks due to inconsistent expansion between components. Moreover, when there is high pressure inside the fixed-bed reactor, the buffer elements 6 can bear some of the stress generated by the pressure, reducing the pressure load on the central tube 2, improving the pressure resistance of the fixed-bed reactor, and reducing the risk of equipment damage due to excessive local pressure. It should be understood that the buffer element can be an expansion ring or other components capable of achieving the above functions, and can be adjusted according to actual conditions; no limitation is made here.
[0036] In an alternative embodiment, the fixed-bed reactor of this application may further include a distillation section located at the top of the reactor shell, with its inlet connected to a gaseous product channel. Therefore, the gaseous product can directly enter the distillation section from the outlet of the gaseous product channel for distillation, allowing the reaction and distillation to be completed within the same equipment. Compared to the traditional process where reaction and distillation are separate, this reduces the intermediate product transport steps, lowers energy loss during material transport, and reduces equipment investment costs.
[0037] In practical applications, the condensate from the external condenser returns to the top of the reactor above the rectification section. This condensate contains incompletely separated THF, as well as some BDO and impurities. After returning to the rectification section, these substances can participate in the rectification process again. The incompletely separated THF can be further purified by rectification, improving the final purity of the product. Meanwhile, BDO can continue to undergo mass transfer and separation within the rectification section, making the rectification process more thorough and efficient. This cyclic rectification method effectively reduces the impurity content in the product and improves product quality.
[0038] This application also provides a tetrahydrofuran production apparatus, including the above-mentioned fixed-bed reactor. Compared with the fixed-bed reactor used in the industrial dehydration and cyclization of BDO to prepare THF, the conversion rate of raw material BDO is improved, the BDO reaction conversion rate is increased from 35-45% to 100%, and the reactor pressure drop is reduced.
[0039] The above description is merely a specific embodiment of this application. Obviously, various modifications and combinations can be made without departing from the spirit and scope of this application. Accordingly, this specification and accompanying drawings are merely exemplary illustrations of this application as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, the intent of this application includes these modifications and variations. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the stated claims.
[0040] It should also be noted that in the apparatus and method of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.
[0041] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.
[0042] The above description has been given for illustrative and descriptive purposes. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although several exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.
Claims
1. A fixed bed reactor, characterized in that, include: The reactor shell, and the central tube, catalyst bed, bottom plate and raw material distribution section provided in the reactor shell; The central tube is located at the axial center of the reactor cylinder. Multiple radial openings are distributed along the axial direction on the sidewall of the central tube. The catalyst bed is located between the central tube and the inner wall of the reactor cylinder. The bottom plate is located at the end of the central tube facing the bottom of the reactor cylinder and is fixedly connected to the inner wall of the reactor cylinder. The bottom end of the reactor cylinder has a feed channel. The raw material distribution section is located at the end of the feed channel near the central tube. The top end of the reactor cylinder has a gaseous product channel. An annular channel exists between the catalyst bed and the inner wall of the reactor cylinder. A fluid channel is opened on the sidewall of the reactor cylinder, and the fluid channel communicates with the annular channel.
2. The fixed bed reactor of claim 1, wherein, The catalyst bed includes a catalyst support assembly and multiple catalyst units. The catalyst support assembly includes multiple stacked corrugated supports with the corrugations of two adjacent corrugated supports tilting in opposite directions. The multiple catalyst units are fixed inside the corrugated supports.
3. The fixed bed reactor of claim 2, wherein, There is a gap between two adjacent corrugated supports, and multiple catalyst units are fixed within the gap.
4. The fixed bed reactor of claim 2, wherein, Multiple catalyst units are fixed within the corrugations of the corrugated support.
5. The fixed bed reactor according to any one of claims 2 to 4, characterized in that Each catalyst unit includes a flexible mesh support and catalyst particles disposed within the flexible mesh support.
6. The fixed bed reactor of claim 5, wherein, The flexible mesh carrier includes a metal flexible mesh carrier, a ceramic flexible mesh carrier, or a polymer flexible mesh carrier.
7. The fixed bed reactor of claim 1, wherein, The fixed-bed reactor also includes multiple buffer elements, which are evenly distributed around the central tube along the axial direction.
8. The fixed bed reactor of claim 1, wherein, The fixed-bed reactor further includes a distillation section; the distillation section is located at the top of the reactor shell, and the inlet of the distillation section is connected to the gaseous product channel.
9. A tetrahydrofuran production apparatus characterized by comprising: Includes the fixed-bed reactor as described in any one of claims 1 to 8.