Fixed bed reactor system for preparing methanol through carbon dioxide hydrogenation and temperature control method thereof

Abstract

The invention relates to the technical field of process reaction control, and discloses a fixed bed reactor system for preparing methanol through carbon dioxide hydrogenation and a temperature control method thereof. The system comprises a reactor module and a measurement and control module, the reactor module comprises at least one cooling cavity; the measurement and control module comprises at least one temperature sensor, at least one heat exchange unit, a circulating pump and a control unit; wherein an inlet of each cooling cavity is connected with an independent liquid inlet pipeline, an outlet of each cooling cavity is connected with an independent liquid outlet pipeline, and the liquid outlet pipeline is connected with the liquid inlet pipeline through the heat exchange unit and the circulating pump to form an independent circulating loop; the control unit is in communication connection with the temperature sensors, the heat exchange units and the circulating pump and used for receiving the real-time temperature data of the cooling cavity and adjusting the working states of the heat exchange units and the flow of the circulating pump. The reactor has the beneficial effects that the limitation of single constant-temperature control of a traditional reactor is overcome, and the designability and regulation and control flexibility of a temperature field of a reactor system are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical process reaction, in particular to a fixed bed reactor system for carbon dioxide hydrogenation to methanol and a temperature control method thereof. BACKGROUND

[0002] Methanol synthesis reaction is usually carried out in a fixed bed reactor under the conditions of 50-100 bar and 200-300℃. Since the methanol synthesis reaction has strong exothermicity and reversibility, the temperature control in the fixed bed reactor is crucial. The "hot spots" formed by local heat accumulation can accelerate the sintering and deactivation of the catalyst, and the excessively high or low reaction temperature can respectively lead to the decrease of methanol selectivity and carbon dioxide conversion rate. Therefore, providing a suitable and uniform temperature environment for the catalyst bed is the key to the efficient and stable operation of the carbon dioxide hydrogenation to methanol process. In addition, for the carbon dioxide hydrogenation to methanol, which is a kind of exothermic reversible reaction, the ideal reactor should be able to maintain a higher temperature in the inlet zone to accelerate the reaction, and then gradually cool down axially to drive the reaction equilibrium to move towards the generation of methanol, thereby improving the methanol yield.

[0003] However, the reactor system in the related art still has the limitations of single temperature control strategy and difficulty in achieving dynamic temperature regulation matching the reaction progress, and the designability and regulation flexibility of the temperature field of the reactor system need to be further improved. SUMMARY

[0004] The present application aims to at least partially solve one of the technical problems in the related art. To this end, the present application proposes a fixed bed reactor system for carbon dioxide hydrogenation to methanol and a temperature control method thereof. The main technical solutions adopted by the present application include: In a first aspect, the present application provides a fixed bed reactor system for carbon dioxide hydrogenation to methanol, which comprises a reactor module and a measurement and control module; the reactor module comprises at least one cooling cavity; the measurement and control module comprises at least one temperature sensor, at least one heat exchange unit, a circulating pump and a control unit; wherein: each temperature sensor is arranged in each cooling cavity respectively, for monitoring the real-time temperature data of the cooling cavity; the inlet of each cooling cavity is connected with an independent liquid inlet pipeline, and the outlet of each cooling cavity is connected with an independent liquid outlet pipeline, and the liquid outlet pipeline is connected with the liquid inlet pipeline through the heat exchange unit and the circulating pump to form an independent circulation loop; the control unit is in communication connection with each temperature sensor, each heat exchange unit and the circulating pump, for receiving the real-time temperature data of the cooling cavity and adjusting the working state of the heat exchange unit and the flow of the circulating pump.

[0005] By setting a reactor module containing independent cooling cavities, and a measurement and control module containing independent temperature sensing, heat exchange and circulation units, multiple temperature control loops independent of each other are constructed. At the same time, the control unit uses real-time temperature data to accurately regulate each loop, which enables the reactor system to set and maintain different target temperatures for different axial regions of the catalyst bed, thereby breaking through the limitations of traditional single constant temperature control of the reactor, significantly improving the designability and regulation flexibility of the temperature field of the reactor system, providing a suitable and uniform temperature environment for the carbon dioxide hydrogenation to methanol reaction, and helping to improve the reaction efficiency and product yield.

[0006] Optionally, the reactor module comprises a reactor shell, a fractal fin and a catalyst bed; wherein: the fractal fin is internally provided with a cavity extending along its axial direction, and the cavity is divided into at least one cooling cavity along the axial direction; the fractal fin is arranged in the reactor shell, and the gap between the fractal fin and the reactor shell constitutes the catalyst bed.

[0007] By coaxially arranging the fractal fin in the reactor shell, the complex fractal sub-fin structure of the outer surface of the fractal fin is used to embed and divide the catalyst bed, achieving efficient radial heat transfer while regularizing the catalyst loading space, making the loading operation more convenient. Further, by dividing the cavity inside the fractal fin into multiple cooling cavities, segmented temperature regulation in the axial direction of the reactor is achieved. Ultimately, the reactor module has both the space and catalyst carrier required for the reaction, and can also be accurately temperature-regulated, thereby providing a stable operating environment for the carbon dioxide hydrogenation to methanol reaction.

[0008] Optionally, the outer surface of the fractal fin is provided with a plurality of circumferentially distributed fractal sub-fins; wherein: the fractal sub-fin adopts a self-similar structure of at least two levels, and the number of branches of each level is 2.

[0009] By arranging the fractal sub-fins circumferentially on the outer surface of the fractal fin, the contact area between the fractal fin and the catalyst bed is increased, and the efficiency of heat transfer is improved.

[0010] Optionally, the reactor shell comprises an upper sealing structure, a cylinder structure and a lower sealing structure; the upper sealing structure is provided with a raw material gas inlet and a liquid inlet pipe; the lower sealing structure is provided with a reaction gas outlet, a liquid outlet pipe and a catalyst discharge port; wherein: the liquid inlet pipeline extends into the reactor shell through the liquid inlet pipe, and is connected with the inlet of the corresponding cooling cavity; the liquid outlet pipeline is connected with the outlet of the corresponding cooling cavity, and extends out of the reactor shell through the liquid outlet pipe to be connected with the corresponding heat exchange unit.

[0011] By setting independent raw material gas inlet, reaction gas outlet and catalyst discharge port, the directional transportation of reaction materials, the smooth discharge of products and the convenience of catalyst maintenance are realized. By connecting the liquid inlet pipeline, the liquid outlet pipeline and the corresponding cooling cavity, an independent cooling circulation loop is constructed, and the independence and accuracy of temperature regulation of each cooling cavity are improved.

[0012] Optionally, the lower sealing structure is filled with a first filling structure; the upper sealing structure is filled with a second filling structure; wherein: the first filling structure is used to support the catalyst bed and uniformly distribute the gas flow; the second filling structure is used to uniformly distribute the gas flow.

[0013] By fully laying porcelain balls in the lower sealing structure to form the first filling structure, the uniformity of the distribution of the reaction gas at the bottom of the catalyst bed is improved while the stable support of the catalyst bed is realized. By partially filling porcelain balls in the upper sealing structure to form the second filling structure, the uniform distribution of the gas flow is realized while unnecessary pressure drop loss is avoided. The combination of the two allows the raw material gas to flow uniformly from entering the reactor to contacting the catalyst, avoiding uneven reaction efficiency caused by local gas flow being too strong or too weak, and also providing a stable support environment for the catalyst bed, prolonging the service life of the catalyst.

[0014] In a second aspect, the application provides a temperature control method for a fixed bed reactor system for carbon dioxide hydrogenation to methanol, applied to the fixed bed reactor system for carbon dioxide hydrogenation to methanol described above; the method comprises: modeling and verification processing based on the structural parameters of the reactor module to obtain a target simulation model of the reactor system; multi-working condition simulation processing based on the target simulation model to determine target temperature data of each cooling cavity; in the actual reaction process, temperature adjustment processing of real-time temperature data of each cooling cavity based on the target temperature data to complete temperature control of the reactor system.

[0015] The actual structural parameters of the reactor system are used for modeling and verification to obtain a target simulation model that can accurately reflect the internal state of the reactor, providing a reliable calculation tool for precise temperature field design. Then, multi-working condition simulation and optimization are carried out based on the model to scientifically determine the optimal target temperature of each cooling cavity, breaking through the limitations of traditional empirical temperature control. Finally, in the actual operation, independent and precise temperature control of each cooling cavity is realized through real-time feedback and independent regulation, effectively solving the problem of single temperature control strategy and the difficulty of matching dynamic temperature regulation with the reaction process in related technologies, significantly improving the designability and regulation flexibility of the temperature field of the reactor system, and ensuring the efficient and stable progress of the carbon dioxide hydrogenation to methanol reaction.

[0016] Optionally, modeling and checking are performed based on the structural parameters of the reactor module to obtain a target simulation model of the reactor system, including: three-dimensional modeling and solving are performed based on the structural parameters, preset control equations and preset boundary conditions to obtain an initial simulation model of the reactor system; wherein the preset control equations include a reaction kinetics equation of carbon dioxide hydrogenation, a reaction kinetics equation of carbon monoxide hydrogenation and a reaction kinetics equation of reverse water gas shift reaction; temperature checking and updating are performed based on the initial simulation model to obtain the target simulation model.

[0017] First, the initial simulation model is constructed using the structural parameters, preset control equations and boundary conditions, which combines the physical structure of the reactor and the reaction rules to provide a basic calculation model for temperature optimization. Then, the temperature checking and parameter updating are performed on the initial simulation model to gradually optimize the structural parameters of the fractal fin, so that the model meets the temperature uniformity requirement. The target simulation model obtained finally can accurately reflect the required temperature state, providing a reliable digital tool for subsequent working condition simulation and temperature control.

[0018] Optionally, three-dimensional modeling and solving are performed based on the structural parameters, preset control equations and preset boundary conditions to obtain an initial simulation model of the reactor system, including: three-dimensional model construction and meshing are performed based on the structural parameters to obtain a simplified geometric model of the reactor system; numerical solving is performed on the simplified geometric model in combination with the preset control equations and the preset boundary conditions to obtain the initial simulation model of the reactor system.

[0019] The simplified geometric model is constructed based on the structural parameters and meshed, which converts the complex physical entity into a standard format for numerical calculation, laying a geometric foundation for subsequent simulation. Then, numerical solving is performed in combination with accurate reaction kinetics equations and physical boundary conditions to obtain an initial simulation model that can initially reveal the complex multi-physical field coupling behavior inside the reactor, providing an important calculation basis for subsequent checking and optimization.

[0020] Optionally, the structure parameters include cylinder parameters and initial fin parameters; the temperature checking and updating based on the initial simulation model are performed to obtain a target simulation model, including: performing temperature uniformity checking based on the initial simulation model to obtain a current checking result; if the current checking result indicates that the initial simulation model does not meet a target temperature condition, performing updating on the initial fin parameters based on the current checking result to obtain updated fin parameters; re-performing three-dimensional modeling and solving based on the updated fin parameters and the cylinder parameters to obtain an updated simulation model of the reactor system, and again performing temperature uniformity checking based on the updated simulation model to obtain an updated checking result; repeating the above updating steps until the updated checking result indicates that the updated simulation model meets the target temperature condition, and taking the updated simulation model as the target simulation model.

[0021] By performing temperature uniformity checking on the initial simulation model, the temperature distribution under the current structure parameters is obtained, which can guide the updating direction of the initial fin parameters. Subsequently, simulation verification is performed again based on the updated parameters, realizing closed-loop optimization of the structure parameters and temperature performance. Finally, the target simulation model meeting the target temperature condition is obtained, providing a precise reference standard for subsequent determination of the target temperature of the actual reaction.

[0022] Optionally, multi-working condition simulation is performed based on the target simulation model to determine target temperature data of each cooling cavity, including: performing multi-working condition simulation based on the target simulation model to obtain carbon dioxide conversion rate and methanol selectivity data under different candidate working conditions; wherein, the candidate working conditions include simulation temperature of a first cooling cavity located at an inlet side of the reactor module, and simulation temperature difference between the first cooling cavity and a second cooling cavity located at an outlet side of the reactor module; performing surface fitting based on the carbon dioxide conversion rate and the methanol selectivity data to obtain a three-dimensional performance surface graph; wherein, the three-dimensional performance surface graph includes a first surface graph describing the carbon dioxide conversion rate and a second surface graph describing the methanol selectivity data; performing working condition optimization based on the three-dimensional performance surface graph to determine a target working condition of the reactor system, and calculating target temperature data of each cooling cavity based on the target working condition.

[0023] Multi-working condition simulation is performed based on the target simulation model to obtain reaction performance data under different temperature parameters, providing a comprehensive calculation basis for working condition optimization. Subsequently, the target working condition considering the conversion rate and the selectivity is quickly and accurately determined by using the intuitive three-dimensional performance surface graph. Finally, the target temperature of each cooling cavity is calculated based on the target working condition, realizing precise design of the axial temperature gradient. Thus, the limitation of traditional empirical temperature control is broken through, and the designability and control flexibility of the temperature field of the reactor are significantly improved, providing key temperature parameter support for efficient and stable operation of the reaction. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the specific embodiments or the prior art, the following will briefly introduce the drawings needed to be used in the description of the specific embodiments or the prior art. Obviously, the drawings described below are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort based on these drawings.

[0025] Figure 1 The structural block diagram of the fixed bed reactor system for carbon dioxide hydrogenation to methanol provided according to an embodiment of the present application; Figure 2a The structural schematic diagram of the reactor module provided according to an embodiment of the present application; Figure 2b The structural schematic diagram of the fractal fin provided according to an embodiment of the present application; Figure 2c The structural schematic diagram of the fractal sub-fin provided according to an embodiment of the present application; Figure 3 The flow chart of the temperature control method of the fixed bed reactor system for carbon dioxide hydrogenation to methanol provided according to an embodiment of the present application; Figure 4a The method flow chart for determining the target simulation model provided according to an embodiment of the present application; Figure 4b The schematic diagram of the simplified geometric model provided according to an embodiment of the present application; Figure 4c The schematic diagram of the initial fin parameter provided according to an embodiment of the present application; Figure 4d The temperature distribution nephogram of the radial section provided according to an embodiment of the present application; Figure 5a The method flow chart for determining the target temperature data provided according to an embodiment of the present application; Figure 5b The three-dimensional performance surface graph for determining the carbon dioxide conversion rate provided according to an embodiment of the present application; Figure 5c The three-dimensional performance surface graph for determining the methanol selectivity provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0026] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0027] It should be noted that in the related art, the widely used fixed bed reactor is mostly of a shell-and-tube structure, and the reaction heat is removed by flowing of a cooling medium outside or inside the tube. Typical representatives thereof include reactors developed by Lurgi Company and Linde Company. Among them, the Lurgi reactor loads catalysts in thousands of vertical tubes, and uses boiling water vaporization cooling outside the tubes. Although this structure is conducive to temperature control, it also leads to limited loading amount of catalysts in a single tube, and the loading and unloading processes of the catalysts are relatively cumbersome. The Linde reactor uses an internal spiral coil as a cooling structure, and loads catalysts in the gap between the coils. Although the loading amount is improved, the uniformity of the catalyst distribution is difficult to guarantee, and the spiral coil has high precision requirements in processing, welding and assembly.

[0028] More importantly, both of the above two types of mainstream reactors aim to maintain the internal temperature of the reactor basically constant. However, for a carbon dioxide hydrogenation to methanol reaction which is an exothermic reversible reaction, an ideal reactor should maintain a higher temperature in the inlet area to promote the reaction rate, and gradually reduce the temperature along the axial direction, so as to promote the reaction equilibrium to move towards the generation of methanol, and finally improve the methanol yield. The related structure still has obvious limitations in this respect. Therefore, a new reactor structure and temperature control method capable of realizing axial gradient temperature control, and having the characteristics of simple loading and radial uniform temperature, are needed to better match the thermodynamic requirements of the reaction, and to improve the product yield and process economy.

[0029] Based on this, in the present embodiment, a carbon dioxide hydrogenation to methanol fixed bed reactor system 100 is provided, as shown in the figure, which comprises a reactor module 110 and a measurement and control module 120. Figure 1 The reactor module can refer to a core device for performing a carbon dioxide hydrogenation to methanol chemical reaction, and can provide a physical space for raw material gas reaction, catalyst loading and heat exchange. The measurement and control module can refer to an auxiliary regulation unit for monitoring and controlling the temperature state inside the reactor module.

[0030] The reactor module can refer to a core device for performing a carbon dioxide hydrogenation to methanol chemical reaction, and can provide a physical space for raw material gas reaction, catalyst loading and heat exchange. The measurement and control module can refer to an auxiliary regulation unit for monitoring and controlling the temperature state inside the reactor module.

[0031] Since the reaction of hydrogenating carbon dioxide to methanol has different temperature requirements along the axial direction, that is, the inlet region needs a higher temperature to accelerate the reaction start-up, and the subsequent region needs to gradually cool down to push the reaction equilibrium to move towards the production of methanol, the reactor module 110 may include at least one cooling chamber 111. These cooling chambers refer to the closed cavity structures arranged along the axial direction inside the reactor module, which can be used to contain and circulate cooling media (such as cooling water or heat transfer oil).

[0032] Specifically, setting the number of cooling chambers to at least one enables basic control of the reactor's internal temperature. For example, a single cooling chamber allows for overall temperature regulation of the catalyst bed. However, setting multiple independent cooling chambers arranged axially allows for differentiated temperature control of different axial regions of the reactor, thus avoiding the problem that a single cooling structure cannot flexibly adapt to axial temperature gradients.

[0033] The measurement and control module 120 includes at least one temperature sensor 121, at least one heat exchange unit 123, a circulating pump 125, and a control unit.

[0034] The heat exchange unit can refer to a functional module that can regulate the temperature of the cooling medium. The circulating pump can refer to a device that provides power for the flow of the cooling medium in the pipeline, enabling the cooling medium to circulate continuously in the loop and ensuring the stable operation of the heat exchange process.

[0035] Specifically, since each cooling chamber needs to independently monitor its temperature and independently adjust its heat exchange effect, the number of temperature sensors and heat exchange units can be the same as the number of cooling chambers. Furthermore, each temperature sensor is installed in each cooling chamber to monitor the real-time temperature data of the cooling chamber. This real-time temperature data can refer to a numerical value that reflects the real-time temperature of the cooling medium within the cooling chamber. For example, this real-time temperature data can be the average temperature within the cooling chamber, or the temperature at the inlet or outlet of the cooling chamber. In actual reaction processes, to ensure measurement consistency and control logic coherence, all temperature sensors are typically uniformly installed at corresponding locations in different cooling chambers, such as the inlet section, central area, or outlet section of the cooling chamber.

[0036] Furthermore, each cooling chamber has an independent inlet pipe 131 at its inlet and an independent outlet pipe 133 at its outlet. The outlet pipe is connected to the inlet pipe via a heat exchange unit and a circulation pump to form an independent circulation loop.

[0037] The liquid inlet pipeline can be a pipeline for delivering the cooling medium to the cooling cavity, and the liquid outlet pipeline can be a pipeline for leading the cooling medium out of the cooling cavity. For example, for a certain cooling cavity, the working process of the circulation loop is as follows: the circulation pump 125 drives the cooling medium (such as heat-conducting oil) to flow from the liquid inlet pipeline 131 corresponding to the cooling cavity into the cooling cavity, to flow out of the liquid outlet pipeline 133 corresponding to the cooling cavity after absorbing or releasing heat, to flow through the heat exchange unit corresponding to the cooling cavity for temperature adjustment (heating or cooling), and to be pumped back to the liquid inlet pipeline 131 by the circulation pump 125 to complete one cycle. Each cooling cavity has such an independent loop.

[0038] The control unit can be a controller or a computer device having the functions of data receiving, logical operation and instruction sending, and can be used to receive temperature data and send control instructions to the heat exchange unit and the circulation pump.

[0039] Specifically, the control unit can be in communication connection with each temperature sensor, each heat exchange unit and the circulation pump, for receiving real-time temperature data of the cooling cavity and adjusting the working state of the heat exchange unit and the flow of the circulation pump.

[0040] The working state can be the operation mode and operation power of the heat exchange unit. For example, when the real-time temperature of the cooling cavity is higher than the target temperature, the cooling power of the heat exchange unit is increased to reduce the temperature of the cooling medium; when the real-time temperature of the cooling cavity is lower than the target temperature, the cooling power is reduced or the heating function is started to increase the temperature of the cooling medium, so that the temperature of the cooling cavity approaches the target value.

[0041] Further, since the flow rate of the cooling medium in the loop affects the heat exchange intensity of the cooling cavity and the response speed to temperature change, the control unit can also adjust the motor frequency or valve opening of the circulation pump to change the flow of the cooling medium in the corresponding loop. For example, in order to quickly respond to temperature fluctuations and optimize system energy consumption, the motor frequency of the circulation pump can be increased to increase the flow of the cooling medium. The greater the flow of the cooling medium, the higher the heat exchange and heat transfer efficiency in the reactor, the faster the heat transfer speed, and the shorter the time required for the entire system to reach a stable state at the set temperature. At the same time, the response speed of temperature regulation can be enhanced to respond to temperature fluctuations in the reaction process in a timely manner.

[0042] Optionally, the reactor system 100 can also be provided with an expansion tank 130, which can be a device for stabilizing the pressure of the circulation loop and supplementing the cooling medium. Specifically, it can be connected between the circulation pump and the liquid outlet pipeline of the circulation loop to absorb the volume expansion of the cooling medium due to temperature change, so as to avoid excessive pressure in the entire loop. At the same time, it can also be used to supplement the cooling medium lost in the circulation process to ensure stable operation of the entire loop.

[0043] In the above embodiments, by setting a reactor module containing an independent cooling cavity, and a measurement and control module containing independent temperature sensing, heat exchange and circulation units, multiple independent temperature control circuits are constructed. At the same time, the control unit is used to accurately regulate each circuit based on real-time temperature data, which enables the reactor system to set and maintain different target temperatures for different axial regions of the catalyst bed, thereby breaking through the limitations of traditional single constant temperature control of the reactor. Finally, the designability and regulation flexibility of the temperature field of the reactor system are significantly improved, providing a suitable and uniform temperature environment for the carbon dioxide hydrogenation to methanol reaction, and helping to improve the reaction efficiency and product yield.

[0044] In some embodiments, please refer to the accompanying drawings Figure 2a The reactor module 110 includes a reactor shell 210, fractal fins 220, and a catalyst bed 230.

[0045] The reactor shell can refer to a closed container structure that constitutes the external contour of the reactor, i.e., the main structure that provides mounting support for various functional components.

[0046] Specifically, the reactor shell includes an upper sealing structure 211, a cylinder structure 213, and a lower sealing structure 215. The upper sealing structure 211 and the cylinder structure 213 are connected by flanges, facilitating the installation and maintenance of internal components. The lower sealing structure 215 is fixed to the cylinder structure 213 by welding to ensure the sealing and pressure-bearing capacity of the connection.

[0047] The upper sealing structure 211 can refer to a closed structure located at the top of the reactor shell, used to seal the upper end of the reactor shell and achieve the introduction of raw gas and the introduction of part of the pipeline.

[0048] Specifically, the upper sealing structure 211 is provided with a raw gas inlet 2111 and a liquid inlet pipe 2113.

[0049] The raw gas inlet 2111 can be used to connect the external raw gas supply pipeline, i.e., to pass the raw gas composed of carbon dioxide and hydrogen into the interior of the reactor shell. The liquid inlet pipe 2113 can be used to provide a passage for the circulation pipeline of the cooling cavity, i.e., the liquid inlet pipe can pass through and extend into the interior of the reactor shell.

[0050] The cylinder structure 213 can refer to a cylindrical structure that constitutes the main part of the reactor, i.e., a main pressure-bearing container that provides mounting space for the catalyst bed and fractal fins and bears the reaction pressure.

[0051] The lower sealing structure 215 can refer to a closed structure located at the bottom of the reactor shell, used to seal the lower end of the reactor shell and achieve the export of reaction products, the backflow of cooling medium, and the loading and unloading of catalysts.

[0052] Specifically, the lower sealing structure 215 can be provided with a reaction gas outlet 2151, a liquid outlet 2153 and a catalyst discharge port 2155.

[0053] The reaction gas outlet 2151 can be used to guide the mixed gas after reaction out of the reactor shell, i.e., to guide the mixture containing methanol, water and unreacted gas after reaction out of the reactor. The inside of the reaction gas outlet 2151 can also be provided with a screen to prevent catalyst particles from escaping. The liquid outlet 2153 can be used to provide a passage for the circulating pipeline of the cooling cavity, i.e., a plurality of independent liquid outlets can pass through and extend out of the reactor shell. The catalyst discharge port 2155 can be used to realize the loading and unloading of the catalyst. Specifically, the catalyst discharge port 2155 is provided with a detachable discharge flange, which can keep the reactor sealed during normal reaction and be detached and opened when loading and unloading is needed.

[0054] Further, the liquid inlet pipeline corresponding to each cooling cavity extends into the reactor shell through the liquid inlet port 2113 on the upper sealing structure 211 and continues to extend inward, and finally connects directly with the inlet of the cooling cavity to realize the delivery of the cooling medium to the cooling cavity. The liquid outlet pipeline is also connected with the outlet of the corresponding cooling cavity and extends out of the reactor shell through the liquid outlet port to be connected with the corresponding heat exchange unit. That is, after the liquid outlet pipeline is drawn out from the outlet of the cooling cavity, it extends to the outside of the reactor shell through the liquid outlet port, and the cooling medium after heat exchange is delivered to the heat exchange unit for temperature regulation.

[0055] It should be noted that the liquid inlet port and the liquid outlet port are through holes provided on the reactor shell for the pipeline to pass through. The liquid inlet pipeline and the liquid outlet pipeline are independent pipelines corresponding to each cooling cavity. Further, the inlet and outlet of each cooling cavity are provided with independent interfaces (such as the oil inlet and the oil return). The plurality of liquid inlet pipelines (such as the oil inlet pipe) corresponding to the number of cooling cavities extend into the reactor shell through the liquid inlet port and are respectively connected with the inlets of the corresponding cooling cavities. Similarly, the plurality of liquid outlet pipelines (such as the oil return pipe) are respectively connected with the outlets of the cooling cavities and extend out through the liquid outlet port to realize the connection between the cooling cavities and the external system.

[0056] By providing independent raw material gas inlets, reaction gas outlets and catalyst discharge ports, the directional delivery of reactants, the smooth discharge of products and the convenience of catalyst maintenance are realized. By connecting the liquid inlet pipeline, the liquid outlet pipeline and the corresponding cooling cavity, an independent cooling circulation loop is constructed, and the independence and precision of temperature regulation of each cooling cavity are improved.

[0057] Further, the lower sealing structure 215 is filled with a first filling structure; the upper sealing structure 211 is filled with a second filling structure.

[0058] The first filling structure can be a chemical inert stack filled in the lower sealing structure. For example, the first filling structure can be a structure formed by gradient arrangement of porcelain balls with different diameters, which can be used to support the catalyst bed and uniformly distribute the gas flow. The second filling structure can also be a chemical inert stack filled in the upper sealing structure, i.e., a structure formed by gradient arrangement of porcelain balls with different diameters, which can be used to uniformly distribute the gas flow.

[0059] It should be noted that the main components of the first filling structure and the second filling structure are both chemical inert porcelain balls, and the difference lies in the filling density, height and function. Specifically, the first filling structure in the lower sealing structure needs to bear the full weight of the catalyst bed, so it needs to be completely filled with porcelain balls to form a solid support base. The second filling structure in the upper sealing structure mainly plays a role in gas flow distribution, so it can be partially filled, with a filling height of about half of the internal space of the upper sealing structure, preferably between 200 mm and 400 mm for different reactors, to avoid excessive filling leading to excessive gas flow resistance.

[0060] When filling, the lower sealing structure can first lay porcelain balls with larger diameters as a base, and then fill porcelain balls with decreasing diameters layer by layer to form a gradient structure. The upper sealing structure starts from below the raw material gas inlet and is laid in the same way to form a gradient structure, so as to disperse the gas flow by utilizing the space between the porcelain balls and the surface characteristics, reduce turbulence, and make the gas pass through the catalyst bed at a more uniform flow rate and flow direction, thereby improving the reaction efficiency and protecting the catalyst.

[0061] By filling the lower sealing structure with porcelain balls to form the first filling structure, the uniformity of the distribution of the reaction gas at the bottom of the catalyst bed is improved while the catalyst bed is stably supported. By partially filling the upper sealing structure with porcelain balls to form the second filling structure, the gas flow is uniformly distributed while unnecessary pressure drop loss is avoided. The combination of the two allows the raw material gas to flow uniformly from the entrance of the reactor to the contact with the catalyst, avoids uneven reaction efficiency caused by excessive or insufficient local gas flow, and at the same time provides a stable support environment for the catalyst bed, prolonging the service life of the catalyst.

[0062] Further, the reactor module 110 further comprises fractal fins 220 and a catalyst bed 230.

[0063] It can be understood that the space between the fractal fins and the reactor shell constitutes a catalyst bed, which is a space region filled with solid catalyst particles, through which the gas phase reactants pass and undergo catalytic reaction, so that the raw material gas contacts with the catalyst in the region to occur the chemical reaction of methanol synthesis from hydrogen.

[0064] The fractal fin 220 can be a metal structure with a specific fractal geometry, and is arranged in the reactor shell. Specifically, the fractal fin is arranged coaxially (i.e. parallel to the direction of the main axis of the reactor cylinder) at the inner central position of the cylinder structure of the reactor shell.

[0065] For example, referring to Figure 2b , the fractal fin 220 is internally provided with a cavity 221 extending in the axial direction thereof, where the axial direction refers to the direction consistent with the length direction of the reactor shell, i.e. the cavity is a cylindrical space extending along the length direction of the reactor. The cavity 221 is internally divided by multiple partitions in the same axial direction to form at least one cooling cavity 111 independent of each other. At the same time, a heat insulation gap 2211 is arranged between adjacent cooling cavities 111 to reduce the heat transfer between adjacent cooling cavities and ensure that the temperature of each cooling cavity is independently controllable.

[0066] Further, reliable sealing structures can also be arranged at the end of the cavity 221, i.e. at the port 2213 connected with the inlet and outlet liquid pipelines. In addition, reliable sealing structures can also be arranged at the wall-penetrating portion 2215 of the inlet and outlet liquid pipelines through the wall of the reactor shell to ensure the sealing of the entire cooling medium circulation loop under high pressure and prevent the leakage of the cooling medium or the mixing of the cooling medium with the reaction gas.

[0067] Further, the outer surface of the fractal fin is also provided with multiple fractal sub-fins uniformly distributed in the circumferential direction.

[0068] The fractal sub-fin can refer to a branch structure extending outward from the main body of the fractal fin. These sub-fins are uniformly arranged in a ring shape on the outer circumference of the fractal fin to increase the contact area with the surrounding catalyst bed.

[0069] Specifically, the fractal sub-fin adopts a self-similar structure of at least two levels, and the number of branches of each level is 2.

[0070] It can be understood that the self-similar structure of at least two levels means that after the first level branch extends from the main body, the first level branch will extend a second level branch similar to itself (if it is a multi-level structure, it will continue to extend), and the shape of each level branch is similar to the overall structure.

[0071] The number of branches of each level is 2, which means that each level branch will be divided into 2 secondary branches. For example, if the first level branch is divided into 2 from the main body, each first level branch will be divided into 2 second level branches.

[0072] For example, referring to Figure 2cAs shown, after each fractal sub-fin extends from the main body, a first level branch (bifurcation number is 2) extends at the first hierarchical point. Then each first level branch, a second level branch similar to itself (bifurcation number is 2) extends at the second hierarchical point, forming a two-level self-similar branch structure, covering the gap area between the fractal fin and the reactor shell, greatly increasing the contact area between the metal fin and the catalyst bed, and forming a complex heat transfer channel. By arranging fractal sub-fins on the outer surface of the fractal fin in a circumferential distribution, the contact area between the fractal fin and the catalyst bed is increased, and the efficiency of heat transfer is improved.

[0073] In the above embodiment, by arranging the fractal fin coaxially in the reactor shell, the complex fractal sub-fin structure on its outer surface is used to embed and divide the catalyst bed, achieving efficient radial heat transfer while regularizing the catalyst loading space, making the loading operation more convenient. Further, by separating the cavity inside the fractal fin into multiple cooling cavities, segmented temperature control in the axial direction of the reactor is achieved. Ultimately, the reactor module has both the space and catalyst carrier required for the reaction, and can also perform precise temperature control, thereby providing a stable operating environment for the carbon dioxide hydrogenation to methanol reaction.

[0074] Each module in the above carbon dioxide hydrogenation to methanol fixed bed reactor system can be implemented in whole or in part by software, hardware, and combinations thereof. The above modules can be embedded in or independent of the processor in the computer device in hardware form, or can be stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to the above modules.

[0075] The carbon dioxide hydrogenation to methanol fixed bed reactor system in this embodiment is presented in the form of functional units. Here, the unit can refer to an actual physical component, or an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory executing one or more software or fixed programs, and / or other devices that can provide the above functions.

[0076] In some embodiments, the present specification also provides a temperature control method for a carbon dioxide hydrogenation to methanol fixed bed reactor system. As shown, the method comprises: Figure 3 As shown, the method comprises: S310, modeling and checking based on the structural parameters of the reactor module to obtain a target simulation model of the reactor system.

[0077] The structure parameters can be physical data describing the actual configuration of the reactor module, such as critical dimensions, shapes, and material properties. For example, the structure parameters can include the dimensions of the cylinder structure, such as the radius of the bottom surface, the length, etc., and can also include the initial fin parameters of the fractal fins, such as the fractal angle, the fin length, and the number of sub-fins, etc.

[0078] Specifically, first, a three-dimensional numerical model of the reactor system can be constructed in the computational fluid dynamics software based on the structure parameters. Then, the initial simulation model is obtained by solving the preset control equation and the preset boundary condition. Subsequently, the temperature uniformity is checked based on the initial simulation model, that is, the temperature distribution of the radial cross-section of the catalyst bed is verified, and it is determined whether the maximum temperature difference meets the preset design requirement (for example, less than 5K). If the check fails, it means that the temperature uniformity of the initial simulation model under the current structure parameters is not up to standard, and the structure parameters need to be adjusted and the modeling and solving need to be performed again until the simulation model obtained can meet the aforementioned temperature uniformity design requirement. The final simulation model meeting the requirement is determined as the target simulation model.

[0079] The target simulation model can be a simulation model meeting the design requirement of the radial temperature uniformity of the catalyst bed and accurately reflecting the temperature transfer and flow rules inside the reactor.

[0080] S320, based on the target simulation model, performing multi-working condition simulation processing to determine the target temperature data of each cooling cavity.

[0081] The working condition can be different combinations of operating parameters used by the simulated reactor system in actual operation, which can include pressure and temperature, etc. For example, taking temperature as an example, the working condition can be different temperature parameter combinations composed of the simulated temperature of the first cooling cavity on the inlet side during the simulation of the reactor system and the simulated temperature difference between the cooling cavity and the last cooling cavity on the outlet side.

[0082] The target temperature data can be the operating temperature value set for each independent cooling cavity, at which the reaction is performed, and the overall performance of the reactor (such as the methanol yield) can reach or approach the optimum.

[0083] Specifically, the category of the operating parameter of the reactor system (e.g. pressure or temperature) can be first defined, and then the value range of the operating parameter is determined, i.e. the numerical interval of the operating parameter affecting the performance of the reactor is set. Subsequently, a plurality of different specific parameter combinations can be selected as a plurality of candidate working conditions within the parameter range. Then, based on the target simulation model, the virtual running calculation is performed on these candidate working conditions one by one, and the performance output data of the reactor under each candidate working condition is obtained, for example, the carbon dioxide conversion rate and the methanol selectivity. After that, based on these performance output data, comprehensive analysis and surface fitting processing are performed to generate a multi-dimensional performance surface graph which can intuitively show the relationship between the performance indicators and the specific simulation parameters. Finally, based on these multi-dimensional performance surface graphs, global optimization processing is performed to identify a specific candidate working condition with the optimal comprehensive performance (i.e. the optimal working condition), and according to the simulation parameter values corresponding to the optimal working condition, the specific temperature value required to be maintained by each cooling cavity is calculated and determined, thereby obtaining the target temperature data.

[0084] S330, in the actual reaction process, the real-time temperature data of each cooling cavity is subjected to temperature adjustment processing based on the target temperature data, so as to complete the temperature control of the reactor system.

[0085] Specifically, when the reactor system is actually started for production, the control unit will continuously read the real-time temperature data measured by the temperature sensor in each cooling cavity. Then, the control unit compares the real-time temperature data of each cooling cavity with the target temperature data corresponding thereto, and generates corresponding control instructions according to the deviation size and direction of the two. These instructions are sent to the corresponding heat exchange unit and circulating pump, so that the real-time temperature of each cooling cavity can quickly and stably reach and maintain near the respective target temperature, by dynamically adjusting the heating or cooling power of the heat exchange unit and the rotating speed of the circulating pump (so as to change the cooling medium flow).

[0086] For example, assuming that the target temperature data of the No. 1 cooling cavity is 563K, and the real-time temperature data fed back by the temperature sensor is 558K, i.e. the current temperature is 5K lower than the target value. After comparison, the control unit determines that the No. 1 cooling cavity needs to be heated. Then, the control unit sends instructions to the No. 1 heat exchange unit connected to the circulating loop of the No. 1 cooling cavity to increase the heating power. At the same time, the rotating speed of the circulating pump driving the flow of the cooling medium in the loop can also be appropriately increased to speed up the heat transfer rate. With the heating, the real-time temperature of the No. 1 cooling cavity gradually rises. The control unit continuously monitors the temperature change, and when the real-time temperature approaches 563K, it starts to reduce the heating power for fine adjustment, and finally stabilizes the temperature at 563K. Similar independent closed-loop control is performed on all cooling cavities, so that the preset optimal temperature gradient can be established and maintained in the entire reactor axial direction.

[0087] In the above embodiments, the actual structural parameters of the reactor system are used for modeling verification, and a target simulation model that can accurately reflect the internal state of the reactor is obtained, providing a reliable calculation tool for precise temperature field design. Subsequently, based on the model, multiple working condition simulations and optimization are carried out, and the optimal target temperature of each cooling cavity is scientifically determined, breaking through the limitations of traditional empirical temperature control. Finally, through real-time feedback and independent regulation in actual operation, independent and precise temperature control of each cooling cavity is realized, effectively solving the problem of single temperature control strategy and the difficulty of achieving dynamic temperature regulation matching the reaction progress in related technologies, significantly improving the designability and regulation flexibility of the temperature field of the reactor system, and ensuring the efficient and stable operation of the carbon dioxide hydrogenation to methanol reaction.

[0088] In some embodiments, please refer to the accompanying Figure 4a , based on the structural parameters of the reactor module, modeling and verification processing are carried out to obtain a target simulation model of the reactor system, including: S410, based on the structural parameters, the preset control equation and the preset boundary condition, three-dimensional modeling and solving processing are carried out to obtain an initial simulation model of the reactor system.

[0089] The preset control equation can be a mathematical equation set of the internal physical and chemical process rules of the reactor. Specifically, it can include the reaction kinetics equation of the carbon dioxide hydrogenation reaction, the reaction kinetics equation of the carbon monoxide hydrogenation reaction, and the reaction kinetics equation of the reverse water gas shift reaction.

[0090] For example, the chemical formula of the carbon dioxide hydrogenation reaction is: The corresponding reaction kinetics equation can be as follows: In the formula, represents the reaction rate constant of the reverse water gas shift reaction, with a unit of ; represents the CO adsorption constant, with a unit of bar -1 ; represents the CO2 adsorption constant, with a unit of bar -1 ; represents the H2O adsorption constant, with a unit of bar -0.5 ; represents the reaction equilibrium constant of the reverse water gas shift reaction, with a unit of bar -2 ; , , , , are fugacity of H2, CO2, CH3OH, H2O and CO, respectively, with a unit of bar.

[0091] The chemical formula for the hydrogenation reaction of carbon monoxide is: The corresponding reaction kinetic equation can be expressed as follows: In the formula, The rate constant for the hydrogenation of carbon dioxide is expressed in units of 1000 m³ / s. ; The equilibrium constant for the hydrogenation of carbon dioxide, expressed in bar. -2 .

[0092] The chemical formula for the reverse water-gas shift reaction is: The corresponding reaction kinetic equation can be expressed as follows: In the formula, This represents the rate constant for the hydrogenation of carbon monoxide, expressed in units of 1000 m³ / s. ; The equilibrium constant representing the hydrogenation reaction of carbon monoxide is a dimensionless number.

[0093] Furthermore, the reaction rate constant and the reaction equilibrium constant in the above equation ( , , , , , , , and It can be calculated using the following formula: In the formula, R Represents the ideal gas constant; T Represents absolute temperature, measured in Kelvin (K).

[0094] It should be noted that, in addition to the reaction kinetic equations mentioned above, the pre-defined governing equations may also include the mass conservation equation, momentum conservation equation, energy conservation equation, and component transport equation required for the usual reaction (which will not be elaborated here).

[0095] The preset boundary condition can refer to a constraint condition for defining the physical state of each region of the reactor system in the simulation calculation, and can clearly define the operation rules and initial state of different parts in the simulation model.

[0096] Exemplarily, the annular gap region between the fractal fins and the cylinder structure (i.e., the catalyst bed) can be defined as a porous medium reaction domain. The fractal fins themselves are defined as a solid domain, and the corresponding thermal conductivity and specific heat capacity are set according to the actual material (such as stainless steel). The contact surface between the porous medium reaction domain and the solid domain can be set as a coupled wall surface to realize heat transfer. The upper end surface of the porous medium reaction domain (the raw material gas inlet side) is set as a velocity inlet condition. For example, according to the simulated process requirements, the space velocity can be specified as 7000h -1 (i.e., the total flow rate of the raw material gas flowing through the catalyst per hour is 7000 times the volume of the catalyst bed), the inlet temperature is 563K, and the raw material gas composition is and The molar ratio of 3:1. The lower end surface (the reaction gas outlet side) is set as a pressure outlet condition, for example, the outlet pressure is set as 60bar. The wall surface of the internal cavity of the fractal fin (i.e., the cooling cavity) is set as a wall surface temperature condition with a specific temperature distribution (for example, linearly decreasing from the inlet temperature of 563K to the outlet temperature of 523K), which is consistent with the target set temperature of the corresponding cooling cavity.

[0097] The initial simulation model can refer to a simulation model that can initially reflect the temperature transfer and flow rules inside the reactor, which has not been verified for temperature uniformity and is only solved based on the original input initial structure parameters.

[0098] Specifically, based on the structure parameters, the preset control equation and the preset boundary condition, the three-dimensional modeling and solving process can be performed. First, based on the structure parameters, a three-dimensional model is constructed and a mesh division process is performed to obtain a simplified geometric model of the reactor system. Then, combined with the preset control equation and the preset boundary condition, the simplified geometric model is numerically solved to obtain an initial simulation model of the reactor system.

[0099] The simplified geometric model can refer to a three-dimensional geometric model obtained by reasonably simplifying the actual reactor physical structure. For the convenience of operation, the simplified geometric model only retains the key structural features that affect flow and heat transfer, such as the main outline of the cylinder structure and the fractal fin, and ignores some non-critical details, such as small bolts and round corners of the reactor. Exemplarily, the simplified geometric model can be as shown in Figure 4b .

[0100] Exemplarily, taking the bottom surface radius of the cylinder structure as 0.2 m, the length as 2 m, and the initial fin parameters of the fractal fin as a fractal angle of 30° and a fin length of 0.5 m as examples, first, the cylindrical profile of the cylinder structure and the three-dimensional geometric structure of the fractal fin can be respectively drawn in a three-dimensional modeling software according to these structure parameters, and then the two are combined according to the actual assembly position to obtain a complete three-dimensional geometric model of the reactor. Subsequently, the three-dimensional geometric model is imported into a meshing software or a pre-processing module of a computational fluid dynamics software to mesh the model. The internal space of the reactor can be divided into a large number of small grid units (such as tetrahedral or hexahedral grids) to obtain a simplified geometric model of the reactor system. The meshing result of the simplified geometric model can continue to refer to Figure 4b .

[0101] Subsequently, the aforementioned preset control equations can be assigned to the meshed calculation domain in the computational fluid dynamics software. At the same time, the preset boundary conditions are accurately applied to the corresponding geometric boundaries. After the settings are completed, the solver is started for iterative calculation, and the software will solve these control equations on each grid unit until the solution of the entire flow field reaches a convergent state. Finally, the results after iteration convergence are output, which include detailed data of the spatial distribution of velocity, pressure, temperature and component concentration, thereby forming an initial simulation model of the reactor system.

[0102] Based on the structure parameters, the simplified geometric model is constructed and meshed, and the complex physical entity is converted into a standard format that can be numerically calculated, thereby laying a geometric foundation for subsequent simulation. Subsequently, the accurate reaction kinetics equations and physical boundary conditions are combined for numerical solution to obtain an initial simulation model that can preliminarily reveal the complex multi-physical field coupling behavior inside the reactor, thereby providing an important calculation basis for subsequent verification and optimization.

[0103] S420, temperature verification and updating processing are performed based on the initial simulation model to obtain a target simulation model.

[0104] It should be noted that the structure parameters can include cylinder parameters and initial fin parameters. The cylinder parameters can refer to physical size data describing the cylinder structure, such as the bottom surface radius, the length and the thickness, etc. The initial fin parameters can refer to structure data describing the initial state of the fractal fin, such as the fractal angle, the fin length, the fin width and the number of sub-fins. Exemplarily, please refer to Figure 4c , where α represents the fractal angle; L0, L1 and L2 represent the lengths of the zeroth level, the first level and the second level fins respectively, which can be set as L0=L1=L2; W0, W1 and W2 represent the widths of the fins at the corresponding levels respectively, which can be set in a proportional relationship of W0=2W1=4W2; and the number of sub-fins is 5 in this example.

[0105] Further, the temperature checking and updating based on the initial simulation model to obtain the target simulation model can comprise: firstly, performing temperature uniformity checking based on the initial simulation model to obtain a current checking result; if the current checking result indicates that the initial simulation model does not meet the target temperature condition, updating the initial fin parameters based on the current checking result to obtain updated fin parameters; subsequently, re-performing three-dimensional modeling and solving based on the updated fin parameters and the cylinder parameters to obtain an updated simulation model of the reactor system, and again performing temperature uniformity checking based on the updated simulation model to obtain an updated checking result; finally, repeating the above updating steps until the updated simulation model meets the target temperature condition, and taking the updated simulation model as the target simulation model.

[0106] It should be noted that, in order to ensure that the design of the reactor can realize the uniform distribution of the radial temperature of the catalyst bed, thereby avoiding the formation of local "hot spots", protecting the activity of the catalyst and improving the reaction efficiency and selectivity, it is necessary to perform temperature uniformity checking to ensure that the temperature distribution meets the design requirements.

[0107] Specifically, the temperature uniformity checking based on the initial simulation model can be performed in a simulation post-processing environment (such as using the post-processing function of the simulation software), and the radial cross section of the catalyst bed at different axial positions is intercepted. Then the temperature data of all grid cells on the cross section is extracted, the highest temperature and the lowest temperature are found out, and the difference between the two is calculated, i.e. the maximum temperature difference of the cross section. Finally, it is determined whether these maximum temperature differences meet the preset target temperature condition to obtain a current checking result. The current checking result can be a judgment conclusion of whether the initial simulation model meets the target temperature condition, i.e. meets or does not meet.

[0108] For example, assuming that the initial simulation model is analyzed, the cross section of the catalyst bed at an axial position corresponding to a cooling cavity is intercepted, and the highest temperature point on the cross section is calculated to be 510K and the lowest temperature point is 502K, i.e. the maximum temperature difference is 8K. If the preset target temperature condition is that the maximum temperature difference of all cross sections is less than 5K, then the current checking result for this cross section is that it does not meet the target temperature condition.

[0109] Subsequently, if the current checking result indicates that the initial simulation model does not meet the target temperature condition, the initial fin parameters can be updated based on the current checking result to obtain updated fin parameters.

[0110] The target temperature condition can be a quantitative standard of temperature uniformity set for the reactor design. Specifically, the standard can be that the maximum temperature difference on any radial cross section of the catalyst bed needs to be less than a certain preset threshold, for example, 5K.

[0111] Specifically, in the case where the updating process needs to be performed, the corresponding initial fin parameters can be selected for adjustment according to the case where the temperature difference exceeds the standard in the current check result, such as increasing the number of sub-fins, adjusting the fractal angle, or changing the fin length, so as to obtain the updated fin parameters. The updated fin parameters are the geometric data of a new set of fractal fins after adjustment.

[0112] It should be noted that since the excessive cross-sectional temperature difference is mainly caused by insufficient radial heat transfer of the fractal fin to the catalyst bed, the heat transfer efficiency can be improved by increasing the heat transfer surface area, thereby reducing the cross-sectional temperature difference. Taking adjusting the number of fractal sub-fins as an example, if the number of sub-fins in the initial fin parameters is 3, and the current check result shows that the temperature difference is too large, based on the above consideration of increasing the heat transfer surface area, the number of sub-fins can be increased to 4 or 5, thereby obtaining the updated fin parameters. In addition, the heat transfer capacity can also be enhanced by adjusting the fractal angle or the fin length. When the fin length increases, the temperature difference gradually decreases, and when the fractal angle increases, the temperature difference first decreases and then increases, and the optimal value needs to be determined through multiple adjustment simulation experiments.

[0113] Then, the updated fin parameters and the cylinder parameters can be used to re-perform three-dimensional modeling and solving process to obtain the updated simulation model of the reactor system, and the temperature uniformity check is again performed based on the updated simulation model to obtain the updated check result.

[0114] Among them, the updated simulation model is a new simulation model constructed based on the updated fin parameters, and the updated check result is a conclusion of whether the updated simulation model meets the target temperature condition.

[0115] Exemplarily, after determining the updated fin parameters, the updated fin parameters can be combined with the original cylinder parameters to repeat the operation of S410, re-construct the three-dimensional geometric model and perform mesh division, and set the same control equation and boundary condition to perform numerical solving to obtain the updated simulation model. Then, the temperature of the radial cross section of the catalyst bed of the model is extracted again to calculate the maximum temperature difference. Taking the target temperature condition of 5K as an example, assuming that the maximum temperature difference obtained this time is 5K, then the updated check result is that the target temperature condition is met. If it is still not met, the parameters need to be continuously adjusted.

[0116] Finally, the steps of the above updating process are repeated until the updated simulation model meets the target temperature condition according to the updated check result, and the updated simulation model is taken as the target simulation model.

[0117] Exemplarily, continuing to take adjusting the number of fractal sub-fins as an example, please refer to Figure 4d , Figure 4dThe temperature distribution cloud map of the radial section and the corresponding maximum temperature difference when the number of sub-fins is 3, 4 and 5, respectively, are shown. Specifically, when the number of sub-fins is 3, the maximum temperature difference is 8K, which does not meet the target temperature condition; after updating the number of sub-fins to 4, the maximum temperature difference decreases to 5K, which meets the target temperature condition; if the number of sub-fins is further updated to 5, the maximum temperature difference can be further reduced to 4K, which also meets the target temperature condition. When the updated check result (such as the check result when the number of sub-fins is 4 or 5) indicates that the target temperature condition is met, the corresponding updated simulation model can be determined as the target simulation model.

[0118] By checking the temperature uniformity of the initial simulation model, the temperature distribution under the current structure parameters is obtained, which can guide the updating direction of the initial fin parameters in the subsequent. Then, based on the updated parameters, the simulation verification is carried out again, realizing the closed-loop optimization of structure parameters and temperature performance. Finally, the target simulation model meeting the target temperature condition is obtained, which provides a precise reference standard for determining the target temperature of the actual reaction in the subsequent.

[0119] In the above embodiments, first, the initial simulation model is constructed by using the structure parameters, the preset control equation and the boundary conditions, which combines the physical structure of the reactor and the reaction rule to provide a basic calculation model for temperature optimization. Then, by checking the temperature of the initial simulation model and updating the parameters, the structure parameters of the fractal fin are gradually optimized, so that the model meets the temperature uniformity requirement. Finally, the target simulation model obtained can accurately reflect the required temperature state, providing a reliable digital tool for subsequent working condition simulation and temperature control.

[0120] In some embodiments, please refer to the accompanying Figure 5a Based on the target simulation model, multi-working condition simulation processing is carried out to determine the target temperature data of each cooling cavity, including: S510, based on the target simulation model, multi-working condition simulation is carried out to obtain the carbon dioxide conversion rate and methanol selectivity data under different candidate working conditions.

[0121] Among them, the candidate working condition can refer to a series of different simulation operating parameter combinations set for exploring the performance of the reactor. Exemplarily, taking temperature as an example, the candidate working condition can include the simulation temperature of the first cooling cavity located at the inlet side of the reactor module, denoted as T1; and the simulation temperature difference between the first cooling cavity and the second cooling cavity located at the outlet side of the reactor module, denoted as ΔT. Among them, the first cooling cavity is the first cooling cavity closest to the inlet of the reactor module (the topmost layer), and the second cooling cavity is the last cooling cavity closest to the outlet of the reactor module (the bottommost layer).

[0122] Specifically, in the case that the category of the operating parameter of the selected reactor system is temperature, a reasonable value range can be first set for the candidate working condition. For example, the exploration range of the simulated temperature T1 of the first cooling cavity is set between 523K and 573K, and the exploration range of the simulated temperature difference AT is set between 0K and 50K. Then in this two-dimensional parameter space, a plurality of representative (T1, AT) numerical combinations are selected, and each combination represents a candidate working condition to be simulated. Then, using the target simulation model that has passed the verification, the temperature conditions corresponding to each candidate working condition (i.e., the axial temperature distribution determined according to T1 and AT) are input as new boundary conditions into the computational fluid dynamics software for independent simulation calculation respectively. After each simulation is completed, the detailed data of the stable operation of the reactor system under the working condition are output, including the molar flow of each component at the inlet and outlet of the reactor module.

[0123] It should be noted that the carbon dioxide conversion rate and the methanol selectivity data are performance indicators calculated based on the molar flow of the components at the inlet and outlet of the reactor. Specifically, the carbon dioxide conversion rate and the methanol selectivity data are calculated according to the corresponding formulas based on the molar flow of the components at the inlet and outlet of the reactor under each working condition.

[0124] Exemplarily, the carbon dioxide conversion rate can be calculated by the following formula : In the formula, represents the molar flow of CO2 at the inlet of the cavity; represents the molar flow of CH3OH at the outlet of the cavity; represents the molar flow of CO at the outlet of the cavity.

[0125] The methanol selectivity data can be calculated by the following formula : Through the above formula, the quantitative evaluation of the performance of the reactor under each candidate working condition can be completed, thereby obtaining a series of corresponding carbon dioxide conversion rate and methanol selectivity data.

[0126] S520, performing surface fitting processing based on the carbon dioxide conversion rate and the methanol selectivity data to obtain a three-dimensional performance surface graph.

[0127] The three-dimensional performance surface graph can be a visual chart that can intuitively display the variation law of the performance with the working condition. Exemplarily, the three-dimensional performance surface graph can be displayed in a coordinate system with the working condition (T1 and AT) as the bottom coordinate axes and the performance indicators as the height coordinate axes. Specifically, the three-dimensional performance surface graph can include a first surface graph describing the carbon dioxide conversion rate and a second surface graph describing the methanol selectivity data.

[0128] Exemplarily, firstly, the simulated temperature T1 of the first cooling cavity is taken as the X-axis coordinate, the simulated temperature difference AT is taken as the Y-axis coordinate, and the calculated carbon dioxide conversion rate and methanol selectivity are taken as the Z-axis coordinates respectively, and then the corresponding three-dimensional scatter plot is drawn by combining the calculated carbon dioxide conversion rate and methanol selectivity data. Subsequently, the surface fitting algorithm is used to perform surface fitting and smoothing processing on these discrete data points, and a three-dimensional performance surface graph covering the entire (T1, AT) parameter exploration range is generated. The finally obtained first surface graph (carbon dioxide conversion rate surface) and second surface graph (methanol selectivity surface) can be respectively as shown in Figure 5b and Figure 5c , which clearly show the distribution of the two performance indicators in the entire operating window.

[0129] S530, based on the three-dimensional performance surface graph, performing operating condition optimization processing to determine the target operating condition of the reactor system, and calculating the target temperature data of each cooling cavity based on the target operating condition.

[0130] The target operating condition can refer to a temperature parameter combination that makes the comprehensive performance of the reactor system relatively optimal.

[0131] It should be noted that when performing operating condition optimization processing, the carbon dioxide conversion rate and the methanol selectivity need to be considered. In view of the comprehensive consideration of reaction economy and product quality, the carbon dioxide conversion rate is generally ensured to reach a high level (entering the conversion rate platform region) first, and then the maximum value of the methanol selectivity is searched in this range, so as to determine the comprehensive optimal operating point.

[0132] Exemplarily, please continue to refer to Figure 5b and 5c , first, observe the first surface graph (carbon dioxide conversion rate surface) Figure 5b , it can be found that when T1 is in the range of 563K to 573K and AT is in the range of 0K to 50K, the carbon dioxide conversion rate changes gently into the platform region. Then, the determined (T1, AT) platform region is mapped to the second surface graph (methanol selectivity surface) Figure 5c . The highest point of the methanol selectivity in this region is searched, and it is found that when T1 is 563K and AT is 50K, the methanol selectivity reaches the maximum value. Therefore, the target operating condition of the reactor system is finally determined, that is, the optimal simulated temperature T1_opt=563K and the optimal simulated temperature difference AT_opt=50K.

[0133] After obtaining the target operating condition, the target temperature data of each cooling cavity can be calculated based on the target operating condition.

[0134] Specifically, for the convenience of calculation, all the cooling cavities can be numbered from top to bottom (along the reactor axis) as the first to the Nth. Then, based on the optimal simulation temperature T1_opt and the optimal simulation temperature difference ΔT_opt under the target working condition, linear calculation is performed to obtain the target temperature data of each cooling cavity. Subsequently, the target setting temperature T of the cooling cavity numbered X can be calculated according to the following formula: In the formula, N represents the number of the last cooling cavity, i.e., the total number of cooling cavities.

[0135] Exemplarily, if the total number of cooling cavities N = 10, the optimal simulation temperature T1_opt = 563 K, and the optimal simulation temperature difference ΔT_opt = 50 K, then based on the above formula, the target temperature data of each cooling cavity numbered from 1 to 10 can be calculated as 563 K, 557.4 K, 551.9 K, 546.3 K, 540.8 K, 535.2 K, 529.7 K, 524.1 K, 518.6 K, and 513 K, respectively.

[0136] Subsequently, in the actual reaction process, after the temperatures of all the cooling cavities are stabilized at the target temperature data calculated above, the raw gas composed of and is introduced into the reactor through the raw gas inlet to perform the carbon dioxide hydrogenation to methanol reaction, and the mixed gas after the reaction is filtered through the screen on the inner side of the reaction gas outlet and then discharged from the reaction gas outlet. Finally, compared with the traditional adiabatic reactor under the same reaction conditions, the methanol yield of the reactor system in the embodiment is increased by 29.3%.

[0137] In the above embodiment, based on the target simulation model, multi-working condition simulation is performed to obtain reaction performance data under different temperature parameters, providing comprehensive calculation basis for working condition optimization. Then, the target working condition considering conversion rate and selectivity is quickly and accurately determined by using the intuitive three-dimensional performance surface graph. Finally, based on the target working condition, the target temperature of each cooling cavity is calculated to realize accurate design of the axial temperature gradient. Thus, the limitations of traditional empirical formula temperature control are broken through, and the designability and control flexibility of the reactor temperature field are significantly improved, providing key temperature parameter support for efficient and stable operation of the reaction.

[0138] It should be understood that, although the steps in the flowcharts above are shown in a sequential order, these steps need not be performed in the order shown. Unless explicitly stated, as long as these steps are performed in the functional order, the order of the steps can be changed. Also, at least some of the steps in the flowcharts above can include multiple steps or multiple stages, which need not be performed in the same order as shown, and can be performed at different times, and need not be performed sequentially, but can be performed in parallel or in an interleaved manner with at least some of the steps or stages of other steps or stages.

[0139] The systems, modules or units illustrated in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer can be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0140] For the sake of description, the above apparatus is described in various units with functions for description. Of course, the functions of the units can be implemented in one or more software and / or hardware in the implementation of the present application.

[0141] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0142] The present application is described with reference to the flowcharts and / or block diagrams of the methods, systems, and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus produce a device that implements the flowcharts and / or block diagrams. Figure 1 The flow or multiple flows and / or blocks Figure 1 The device that implements the functions specified in the flow or multiple flows and / or blocks.

[0143] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the Figure 1 function specified in the flow or flows and / or blocks Figure 1 of the block or blocks.

[0144] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the Figure 1 function specified in the flow or flows and / or blocks Figure 1 of the block or blocks.

[0145] In this description, references to "one embodiment", "some embodiments", "an example", "a specific example", or "some examples", etc., mean that a particular feature, structure, material, or characteristic is included in at least one embodiment or example of the present application. The appearances of the above expressions in various places in the description are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0146] In addition, the terms "first", "second", and the like, do not necessarily indicate any order, quantity, combination, or importance, but rather are used to nomenclature different components and / or structures. Thus, a "first" and / or "second" feature can include one or more of either feature without expressly reciting the number of the feature. Furthermore, the meaning of "a", "an", and "the" include singular and plural references, unless the context clearly dictates otherwise.

[0147] It is also noted that the terms "comprise", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0148] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each of the embodiments focuses on the difference from other embodiments. The above only describes the embodiments of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the scope of the claims of the present application.

[0149] Although the embodiments of the present application are described in conjunction with the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A fixed bed reactor system for the hydrocarbon of carbon dioxide to methanol, characterized in that, The reactor module comprises at least one cooling cavity, and the control module comprises at least one temperature sensor, at least one heat exchange unit, a circulating pump and a control unit. Each temperature sensor is arranged in each cooling cavity to monitor real-time temperature data of the cooling cavity. The inlet of each cooling cavity is connected with an independent liquid inlet pipeline, and the outlet of each cooling cavity is connected with an independent liquid outlet pipeline. The control unit is in communication connection with each temperature sensor, each heat exchange unit and the circulating pump, and is used for receiving the real-time temperature data of the cooling cavity and adjusting the working state of the heat exchange unit and the flow of the circulating pump.

2. The system of claim 1, wherein, The reactor module comprises a reactor shell, fractal fins and a catalyst bed. The fractal fins are internally provided with cavities extending along the axial direction, and at least one cooling cavity is formed in the cavities. The fractal fins are arranged in the reactor shell, and the gap between the fractal fins and the reactor shell constitutes the catalyst bed.

3. The system of claim 2, wherein, The outer surface of the fractal fins is provided with a plurality of circumferentially distributed fractal sub-fins.

4. The system of claim 2, wherein, The reactor shell comprises an upper sealing structure, a cylinder structure and a lower sealing structure. The liquid inlet pipeline extends into the reactor shell through the liquid inlet port and is connected with the inlet of the corresponding cooling cavity. The liquid outlet pipeline is connected with the outlet of the corresponding cooling cavity and extends out of the reactor shell through the liquid outlet port to be connected with the corresponding heat exchange unit.

5. The system of claim 4, wherein, The lower sealing structure is filled with a first filling structure, and the upper sealing structure is filled with a second filling structure. The first filling structure is used for supporting the catalyst bed and uniformly distributing airflow. The second filling structure is used for uniformly distributing airflow.

6. A temperature control method of a fixed bed reactor system for the methanol synthesis from carbon dioxide hydrogenation, characterized in that, The method is applied to the fixed bed reactor system for preparing methanol by carbon dioxide hydrogenation according to any one of claims 1-5, and the method comprises: Modeling and checking are performed based on the structural parameters of the reactor module to obtain a target simulation model of the reactor system; Multi-working condition simulation is performed based on the target simulation model to determine target temperature data of each cooling cavity; In the actual reaction process, real-time temperature data of each cooling cavity is adjusted based on the target temperature data to complete temperature control of the reactor system.

7. The method of claim 6, wherein, The modeling and checking based on the structural parameters of the reactor module to obtain the target simulation model of the reactor system comprise: The three-dimensional modeling and solving processing are performed based on the structure parameters, preset control equations and preset boundary conditions to obtain an initial simulation model of the reactor system; wherein, the preset control equations include a reaction kinetics equation of carbon dioxide hydrogenation reaction, a reaction kinetics equation of carbon monoxide hydrogenation reaction and a reaction kinetics equation of reverse water gas shift reaction; The temperature checking and updating processing are performed based on the initial simulation model to obtain the target simulation model.

8. The method of claim 7, wherein, The three-dimensional modeling and solving processing based on the structure parameters, preset control equations and preset boundary conditions to obtain the initial simulation model of the reactor system includes: The three-dimensional model construction and grid division processing are performed based on the structure parameters to obtain a simplified geometric model of the reactor system; The numerical solving processing is performed on the simplified geometric model in combination with the preset control equations and the preset boundary conditions to obtain the initial simulation model of the reactor system.

9. The method of claim 7, wherein, The structure parameters include cylinder parameters and initial fin parameters; The temperature checking and updating processing based on the initial simulation model to obtain the target simulation model includes: The temperature uniformity checking is performed based on the initial simulation model to obtain a current checking result; If the current checking result indicates that the initial simulation model does not meet a target temperature condition, the initial fin parameters are updated based on the current checking result to obtain updated fin parameters; The three-dimensional modeling and solving processing are performed again based on the updated fin parameters and the cylinder parameters to obtain an updated simulation model of the reactor system, and the temperature uniformity checking is performed again based on the updated simulation model to obtain an updated checking result; The above updating processing is repeated until the updated checking result indicates that the updated simulation model meets the target temperature condition, and the updated simulation model is taken as the target simulation model.

10. The method of claim 6, wherein, The multi-working condition simulation processing based on the target simulation model to determine the target temperature data of each cooling cavity includes: The multi-working condition simulation is performed based on the target simulation model to obtain carbon dioxide conversion rate and methanol selectivity data under different candidate working conditions; wherein, the candidate working conditions include a simulation temperature of a first cooling cavity located at an inlet side of the reactor module and a simulation temperature difference between the first cooling cavity and a second cooling cavity located at an outlet side of the reactor module; The surface fitting processing is performed based on the carbon dioxide conversion rate and the methanol selectivity data to obtain a three-dimensional performance surface graph; wherein, the three-dimensional performance surface graph includes a first surface graph describing the carbon dioxide conversion rate and a second surface graph describing the methanol selectivity data; The working condition optimization processing is performed based on the three-dimensional performance surface graph to determine a target working condition of the reactor system, and the target temperature data of each cooling cavity is calculated based on the target working condition.

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