A methanol synthesis reactor, a carbon dioxide hydrogenation methanol system and a method thereof

Abstract

This invention provides a methanol synthesis reactor, a carbon dioxide hydrogenation to methanol system, and a method thereof. The system includes a methanol synthesis reactor, a gas-liquid separator, a distillation unit, and a circulating compressor. The methanol synthesis reactor has a main catalyst bed and heat exchange tube bundles embedded therein. The heat exchange tube bundles are divided into two groups, staggered between inner and outer tube sheets at both ends. A pre-reaction catalyst bed is filled between the inner and outer tube sheets. The feed gas enters the heat exchange tube bundle at the outer tube sheet, is heated by the main catalyst bed, and then enters the pre-reaction catalyst bed for a pre-hydrogenation reaction before entering the main catalyst bed. The reaction product outlet is connected to the reboiler of the distillation unit, utilizing the waste heat to heat the distillation process. This invention improves the reactor's thermal management efficiency and operational stability, as well as its energy utilization efficiency and reaction efficiency, through optimized reactor structure design and cascaded utilization of system energy, achieving a low-energy-consumption carbon dioxide hydrogenation to methanol process.

Description

Technical Field

[0001] This invention belongs to the field of C1 chemical technology, specifically relating to a methanol synthesis reactor, a carbon dioxide hydrogenation methanol production system and method, and particularly to a system and process for converting carbon dioxide into methanol through a hydrogenation reaction. Background Technology

[0002] The catalytic hydrogenation of carbon dioxide to methanol is an important pathway to achieving carbon resource recycling and green hydrogen utilization. An industrially competitive process requires not only high-performance catalysts but also efficient reaction engineering design and system energy integration to overcome reaction thermodynamic limitations, reduce process energy consumption, and improve feedstock utilization. Currently, technological development in this field mainly focuses on optimizing core aspects such as reactor type, heat management, and separation processes. However, it still faces a series of challenges, including large system pressure drops, low high-quality reaction heat utilization, high energy consumption of separation units, and carbon dioxide recycling losses due to dissolution.

[0003] In existing technologies, a representative approach employs a configuration of adiabatic and isothermal reactors connected in series. For example, CN119345713 B attempts to solve the heat coupling problem by connecting adiabatic and isothermal reactors in series. However, those skilled in the art are generally limited by the traditional multi-reactor series configuration and have failed to recognize the feasibility of achieving heat self-balancing and cascade utilization within a single reactor. Its complex series system and membrane separation unit not only increase investment but also increase system pressure drop and control difficulty.

[0004] Another approach focuses on improving conversion rates through differentiated management of reaction conditions (e.g., CN120349223A). This technology employs a two-stage reaction process: "low-pressure, high-temperature" and "high-pressure, low-temperature." After separating methanol from the first-stage reaction product, the remaining gas is compressed to a higher pressure for the second-stage reaction. This method, through segmented optimization of thermodynamic driving forces, does indeed help improve the single-pass conversion rate. However, its process requires multi-stage compression, resulting in significant power consumption of the circulating compressor. Furthermore, its heat integration is largely limited to preheating the feed gas, failing to directly and efficiently utilize the high-grade reaction product heat energy to drive energy-intensive units such as distillation. The overall thermal energy utilization of the system has considerable room for improvement.

[0005] In addition, the more traditional isothermal tube-bundle reactor hydrogenation system (such as CN118142444 A) represents the common configuration of the current one-step process. The heat of reaction is removed by boiling water in the shell side and steam is generated. Although the reaction temperature is stably controlled, the quality (pressure) of the generated steam often does not match the heat requirements of the process itself, and the direct utilization rate of the heat of reaction within the process system is low.

[0006] In summary, existing carbon dioxide hydrogenation to methanol systems and processes still have room for improvement in reactor structure design, catalyst bed functional zoning, and system energy cascade utilization. In particular, how to achieve efficient preheating of feed gas, deep coupling of low-temperature pre-reaction and main reaction within a compact device, and fully utilize reaction waste heat to reduce distillation unit energy consumption are pressing technical problems that need to be solved in this field. Therefore, there is an urgent need for a novel system and process method that can comprehensively optimize reactor structure design and thermal management efficiency, and achieve efficient integration of reaction and separation processes. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a methanol synthesis reactor, a carbon dioxide hydrogenation methanol production system and method, especially a carbon dioxide hydrogenation methanol production system and process with compact structure, high energy utilization efficiency and excellent reaction performance, so as to solve the problems of unreasonable functional zoning of reactors and insufficient energy cascade utilization in the prior art.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a methanol synthesis reactor 100, including a reactor shell 101, a main catalyst bed 102 disposed within the reactor shell 101, reactor feed inlets 108 located at both ends of the reactor shell 101, and a reaction product outlet 109 provided on the reactor shell 101. A heat exchange tube bundle 103 is embedded in the main catalyst bed 102. Both ends of the main catalyst bed 102 are provided with an inner tube sheet 106, a flow guide tube sheet 107, and an outer tube sheet 111 in sequence. The main catalyst bed 102 is located between the inner tube sheets 106. A tube sheet gap is formed between the inner tube sheet 106 and the flow guide tube sheet 107. The tube sheet gap is filled with a pre-reacted catalyst bed 112. A flow guide gap is formed between the flow guide tube sheet 107 and the outer tube sheet 111. The tube sheet gap and the flow guide gap are connected through the flow guide tube sheet 107. The heat exchange tube bundle 103 is divided into a first group of heat exchange tubes and a second group of heat exchange tubes. One end of the first group of heat exchange tubes is fixed to the outer tube sheet 111 at one end of the main catalyst bed 102 and the inner tube sheet 106 at the other end of the main catalyst bed 102. The second group of heat exchange tubes is the opposite of the first group of heat exchange tubes, with one end fixed to the inner tube sheet 106 at one end of the main catalyst bed 102 and the outer tube sheet 111 at the other end of the main catalyst bed 102. The heat exchange tubes fixed to the inner tube sheet 106 are connected to the tube sheet on the same side of the inner tube sheet. The main catalyst bed 102 is provided with screens 110 on both the inner and outer sides. The inner screen forms an inner gas chamber, and the outer screen and the reactor shell 101 form an outer gas chamber. The inner and outer screens extend to the inner tube sheets 106 on both sides. The main catalyst bed 102 is located in the space formed by the inner screen, the outer screen and the inner tube sheet 106. When the inner gas chamber is the gas distribution chamber 105, the inner gas chamber extends from the inner tube sheet 106 to the guide tube sheet 107 and communicates with the guide gap. The extended part is a solid plate. The outer gas chamber is the gas collection chamber 104. The gas collection chamber 104 is connected to the reaction product outlet 109 on the reactor shell 101. The two ends of the gas collection chamber 104 are the inner tube sheet 106. When the outer gas chamber is the gas distribution chamber 105, the outer gas chamber extends from the inner tube sheet 106 to the guide tube sheet 107 and communicates with the guide gap. The extended part is a solid plate. The inner gas chamber is the gas collection chamber 104. One end of the gas collection chamber 104 is the inner tube sheet 106, and the other end passes through the inner tube sheet 106, the guide tube sheet 107, and the outer tube sheet 111, extending to the reactor shell 101 and communicating with the reaction product outlet 109. The extended part is a solid plate.

[0010] As one embodiment of the present invention, the raw material gas enters the gas inlet chamber formed by the reactor shell 101 and the outer tube sheet 111 from the reactor inlet 108, passes through the main catalyst bed 102 through the heat exchange tube bundle 103 fixed on the outer tube sheet 111, flows out from the inner tube sheet 106 at the other end and enters the tube sheet gap, then passes through the guide tube sheet 107 and enters the guide gap, enters the gas distribution chamber 105 which is connected to the guide gap, then passes through the main catalyst bed 102 and reaches the gas collection chamber 104, and is discharged from the reaction product outlet 109.

[0011] In one embodiment of the present invention, the heat exchange tube inlet on the outer tube sheet 111 is connected to the reactor feed inlet 108 through the air inlet chamber formed by the reactor shell 101 and the outer tube sheet 111. The reactor head is connected to the reactor feed inlet for introducing raw material gas containing carbon dioxide and hydrogen.

[0012] In one embodiment of the present invention, the two sets of heat exchange tubes are arranged in a staggered manner at fixed positions on the outer tube sheets 111 at both ends. The heat exchange tube bundle 103 is a reinforced heat transfer tube, which is selected from one or more of the following: nail-head tubes, spiral groove tubes, cross-ribbed tubes, tapered tubes, or finned tubes. The difference in the number of the two sets of heat exchange tubes is preferably no more than 5, and more preferably the same number.

[0013] As one embodiment of the present invention, the height of the main catalyst bed 102 (the height of the heat exchange tube 103) and the height of the tube sheet gap (the height of the pre-reaction catalyst bed 112) are set according to the requirements of the feed space velocity and reaction temperature during the preparation process, so as to ensure that the feed gas reaches the activation temperature of the pre-reaction catalyst bed 112 after being preheated by the main catalyst bed 102, and the reaction gas after passing through the pre-reaction catalyst bed 112 reaches the activation temperature of the main catalyst bed 102.

[0014] In one embodiment of the present invention, the inner gas chamber is preferably cylindrical, and its diameter is set according to the reactor operating load to ensure that the maximum linear velocity of the gas in the inner gas chamber is 1~10 m / s. The height of the guide gap is 0.5~2 times the diameter of the inner gas chamber, preferably 1.0 times.

[0015] In one embodiment of the present invention, the outer air chamber is preferably shaped as a circular annular cylinder. The width of the annular cylinder is 0.1 to 0.5 times the diameter of the inner air chamber.

[0016] In one embodiment of the present invention, the feed gas enters the heat exchange tube from one side of the outer tube sheet 111 and flows out into the tube sheet gap from one side of the inner tube sheet 106. During operation of the methanol synthesis reactor, the feed gas is preheated by the heat released from the reaction in the catalyst layer as it passes through the heat exchange tube.

[0017] As one embodiment of the present invention, the activation temperature of the catalyst used in the pre-reaction catalyst bed 102 is 60-90°C lower than that of the catalyst used in the main catalyst bed 102.

[0018] In one embodiment of the present invention, the catalyst used in the pre-reaction catalyst bed 102 is a molybdenum sulfide-based catalyst and / or a molybdenum carbide-based catalyst. This catalyst has a relatively low activation temperature (around 180°C). The preheated feed gas passes through the pre-reaction catalyst bed 102 in the tube sheet gap, reacting under the action of the catalyst. Part of the feed gas reacts, releasing heat. The feed gas is further preheated to the activation temperature of the main catalyst (around 250°C), and then reacts after entering the main catalyst bed 102.

[0019] As one embodiment of the present invention, the main catalyst bed 102 is filled with a copper-based catalyst and / or a zirconium-based catalyst.

[0020] In one embodiment of the present invention, the screen 110 is a wound wire screen. The fully mixed raw material gas enters the gas distribution chamber 105 through the guide gap, passes through the screen 110 and enters the main catalyst bed 102, where it reacts under the action of the main catalyst. The reacted gas then passes through the screen again and enters the gas collection chamber 104.

[0021] In one embodiment of the present invention, the guide tube plate 107 is a wound wire screen. The outlet of the heat exchange tube on the inner tube plate is connected to the gas distribution chamber through the tube plate gap, so that the preheated raw material gas enters the main catalyst bed after passing through the pre-reaction catalyst bed. The raw material gas is fully mixed after entering the guide gap through the guide tube plate. The raw material gas reacts uniformly in the pre-reaction catalyst bed, and the gas passing through the heat exchange tube is mixed evenly in the guide gap before entering the gas distribution chamber and the main catalyst bed. If there is no guide gap, the gas directly enters the gas distribution chamber (the tube plate gap is directly connected to the gas distribution chamber 105) and the main catalyst bed from the pre-reaction catalyst bed. Due to the different distances of the inner and outer heat exchange tubes through the pre-reaction catalyst bed, that is, the different reaction times of the gas in the pre-reaction catalyst bed, the different flow paths lead to different gas temperatures (especially insufficient preheating temperature on the inner side) and different degrees of reaction of the raw material gas (inhomogeneous material composition), resulting in uneven reaction when entering the main catalyst bed. At the same time, it will also cause a large difference in the temperature of the pre-reaction catalyst bed.

[0022] In one embodiment of the present invention, when the inner gas chamber is a gas distribution chamber 105, both sides of the gas distribution chamber 105 are connected to the guide gap; the outer screen, the inner tube plates 106 on both sides, and the reactor shell 101 form a gas collection chamber 104. When the inner gas chamber is a gas collection chamber 104, both sides of the gas distribution chamber 105 are connected to the guide gap; the inner screen and one side of the inner tube plate 106 form a gas collection chamber 104, and the other side is connected to the reaction product outlet 109. The positions of the gas distribution chamber and the gas collection chamber of the present invention can be interchanged, that is, the gas collection chamber is designed to be located inside the main catalyst bed, while the gas distribution chamber is located outside, or the gas distribution chamber is located inside the main catalyst bed, while the gas collection chamber is located outside.

[0023] In a second aspect, the present invention provides a system for producing methanol by carbon dioxide hydrogenation, comprising the methanol synthesis reactor 100, the distillation unit reboiler 200, the gas-liquid separator 400, and the distillation unit 600 connected in sequence. The distillation unit reboiler 200 is provided with a hot end inlet and a hot end outlet. The reaction product outlet 109 of the methanol synthesis reactor 100 is connected to the hot end inlet of the distillation unit reboiler 200. The inlet of the gas-liquid separator 400 is connected to the hot end outlet of the distillation unit reboiler 200. The gas-liquid separator 400 is provided with a liquid phase outlet and a gas phase outlet; the liquid phase outlet is connected to the feed inlet of the distillation unit 600.

[0024] In one embodiment of the present invention, the gas phase outlet of the gas-liquid separator 400 is connected to the reactor inlet 108 of the methanol synthesis reactor 100. A circulating compressor 500 is installed on the gas phase outlet connecting pipeline of the gas-liquid separator 400. The gas phase outlet of the gas-liquid separator is connected to the inlet of the circulating compressor, and the outlet of the circulating compressor is connected to the reactor inlet via pipelines that are combined with fresh hydrogen and carbon dioxide feedstock pipelines.

[0025] In one embodiment of the present invention, the reaction product of the methanol synthesis reactor 100 is used as a heat source and is fed into the reboiler 200 of the distillation unit to provide heat to the distillation unit 600.

[0026] As one embodiment of the present invention, a waste heat recovery unit 300 is provided between the reboiler 200 of the distillation unit and the gas-liquid separator 400; the hot end inlet of the waste heat recovery unit 300 is connected to the hot end outlet of the reboiler 200 of the distillation unit, and the hot end outlet of the waste heat recovery unit 300 is connected to the inlet of the gas-liquid separator 400.

[0027] In one embodiment of the present invention, the methanol synthesis reactor 100 has a reactor inlet 108 connected to an inlet pipe, which is preheated by a waste heat recovery unit 300. The cold end inlet of the waste heat recovery unit is used to introduce fresh hydrogen and carbon dioxide feedstock to be preheated.

[0028] Thirdly, the present invention also provides a process for producing methanol by carbon dioxide hydrogenation using the above-described system, comprising the following steps: (a) The raw material gas enters the gas inlet chamber formed by the reactor shell 101 and the outer tube sheet 111 from the reactor inlet 108. It passes through the main catalyst bed 102 through the heat exchange tube bundle 103 fixed on the outer tube sheet 111 and is heated by the main catalyst bed outside the tubes. It flows out from the inner tube sheet 106 at the other end and enters the tube sheet gap. It undergoes a pre-hydrogenation reaction in the pre-reaction catalyst bed. The reaction products then pass through the guide tube sheet 107 and enter the guide gap. After being mixed evenly, they enter the gas distribution chamber 105 connected to the guide gap. Then, they pass through the screen 110 and enter the main catalyst bed 102 to carry out a hydrogenation reaction, generating a reaction product containing methanol. The product passes through the screen to the gas collection chamber 104 and flows out of the methanol synthesis reactor 100 from the reaction product outlet 109. (b) The reaction product obtained in step (a) is used as a heat source and passed into the reboiler 200 of the distillation unit for heat exchange. After cooling, the cooled process stream is obtained. (c) The cooled process stream obtained in step (b) is fed into the gas-liquid separator 400 for gas-liquid separation to obtain a liquid phase rich in methanol and a gas phase rich in unreacted hydrogen and carbon dioxide. (d) The gas phase obtained in step (c) is pressurized by a circulating compressor and mixed with the replenished fresh hydrogen and carbon dioxide feed gas, and then returned to step (a) for reaction; (e) The liquid phase obtained in step (c) is sent to the distillation unit 600 for separation to obtain refined methanol product and by-product fusel oil.

[0029] In a preferred embodiment of the present invention, in step (b), the temperature is lowered to 110-130°C to obtain the cooled process stream. As a preferred embodiment of the present invention, in step (c), the operating temperature of the gas-liquid separation is 50°C to 95°C.

[0030] As a preferred embodiment of the present invention, in step (a), the operating pressure of the methanol synthesis reactor is 2.0 MPa to 8.0 MPa, the pressure drop of the main catalyst bed is not higher than 0.05 MPa, and the maximum radial temperature difference of the bed is less than 7°C.

[0031] As a preferred embodiment of the present invention, in step (b), after the reaction product enters the reboiler 200 of the distillation unit, it also enters the waste heat recovery unit 300 to exchange heat with the fresh hydrogen and carbon dioxide feed gas to be preheated.

[0032] Compared with the prior art, the present invention has the following beneficial effects: (1) By designing the methanol synthesis reactor with a double tube sheet structure and two sets of staggered heat exchange tube bundles, and feeding from both ends of the reactor, the present invention realizes the countercurrent preheating of the raw material gas and the original displacement of the reaction heat, resulting in high heat exchange efficiency, reduced bed pressure, uniform bed temperature distribution, avoiding local overheating, and improving reaction conversion rate, selectivity and catalyst life.

[0033] (2) A pre-reaction catalyst bed is set in the gap between the inner and outer tube sheets, so that the feed gas passes through the pre-reaction zone before entering the main catalyst bed. The low-temperature active catalyst (such as molybdenum sulfide or molybdenum carbide-based catalyst) packed in this zone pre-converts some carbon dioxide and hydrogen into methanol or active intermediates, reducing the load on the main reaction zone and improving the overall reaction rate and single-pass conversion rate. Compared with the two-stage reaction compression process adopted in CN120349223 A, this invention achieves precise management of the reaction load in a single reactor by setting up a pre-reaction zone, avoiding the huge energy consumption caused by multi-stage compression.

[0034] (3) A flow guide plate is set between the inner tube sheet and the outer tube sheet. The latter forms a flow guide gap with the outer tube sheet, which can significantly improve the uniformity and controllability of the reactor flow field and temperature field.

[0035] (4) Connecting the reaction product outlet to the reboiler of the distillation unit allows for the direct use of the waste heat from the high-temperature reaction products to provide heat for the distillation process, achieving cascaded utilization of system energy, significantly reducing external heat source consumption, and resulting in significant energy savings. Further installation of a waste heat recovery unit can utilize the residual heat from the reboiler outlet stream to preheat fresh feed gas, further improving the energy recovery rate and reducing the overall energy consumption of the system. Attached Figure Description

[0036] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 A process flow diagram for producing methanol by carbon dioxide hydrogenation; Figure 2 This is a schematic diagram of a thermally coupled reactor structure; Figure 3 This is a schematic diagram of another thermally coupled reactor structure; Figure 4 Flowchart of another process for producing methanol by carbon dioxide hydrogenation; Explanation of reference numerals in the attached figures: 100-Methanol synthesis reactor; 200-Reboiler of distillation unit; 300-Waste heat recovery unit; 400-Gas-liquid separator; 500-Circulating compressor; 600-Distillation unit; 101-Reactor shell; 102-Main catalyst bed; 103-Heat exchange tube bundle; 104-Gas collection chamber; 105-Gas distribution chamber; 106-Inner tube sheet; 107-Flow guide tube sheet; 108-Reactor inlet; 109-Reaction product outlet; 110-Screen; 111-Outer tube sheet; 112-Pre-reaction catalyst bed. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are only for explaining the invention and not for limiting it. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0038] Example 1 In a first aspect, the present invention provides a methanol synthesis reactor 100, which is a thermally coupled reactor, such as... Figure 2 As shown, it includes a reactor shell 101 made of stainless steel, a main catalyst bed 102 arranged axially inside the reactor shell 101, a reactor feed inlet 108 located at both ends of the reactor shell 101, and a reaction product outlet 109 provided on the reactor shell 101. A heat exchange tube bundle 103 (accounting for 45% of the volume of the main catalyst bed 102) is uniformly embedded in the main catalyst bed 102. At both ends of the main catalyst bed 102, an inner tube sheet 106, a flow guide tube sheet 107, and an outer tube sheet 111 are sequentially arranged. The main catalyst bed 102 is located between the inner tube sheets 106, forming a tube sheet gap (200 mm high) between the inner tube sheets 106 and the flow guide tube sheets 107. A pre-reaction catalyst bed 112 is filled in the tube sheet gap. A flow guide gap (50 mm high) is formed between the flow guide tube sheet 107 and the outer tube sheet 111. The tube sheet gap and the flow guide gap are connected through the flow guide tube sheet 107. The pre-reaction catalyst is a molybdenum carbide-based catalyst. The main catalyst bed 102 is filled with a copper-based catalyst. The heat exchange tube bundle 103 is divided into a first group of heat exchange tubes and a second group of heat exchange tubes, with 50 tubes in each group. One end of the first group of heat exchange tubes is fixed to the outer tube sheet 111 at one end of the main catalyst bed 102 and the inner tube sheet 106 at the other end of the main catalyst bed 102. The second group of heat exchange tubes is the opposite of the first group of heat exchange tubes, with one end fixed to the inner tube sheet 106 at one end of the main catalyst bed 102 and the outer tube sheet 111 at the other end of the main catalyst bed 102. The heat exchange tubes fixed to the inner tube sheet 106 are connected to the tube sheet on the same side of the inner tube sheet. The two groups of heat exchange tubes are spiral groove tubes, and their fixed positions on the tube sheets at both ends are staggered to ensure the uniformity of fluid distribution. The main catalyst bed 102 is equipped with screens 110 (wire-wound screens, which can fix the catalyst and also ensure normal gas passage) on both the inner and outer sides. The inner and outer screens extend to the inner tube sheets 106 on both sides. The main catalyst bed 102 is located in the space formed by the inner and outer screens and the inner tube sheet 106. The inner screen forms a cylindrical inner gas chamber with a diameter of 100 mm. The outer screen and the reactor shell 101 form an annular cylindrical outer gas chamber (annular width of 20 mm). The inner gas chamber further extends from the inner tube sheet 106 to the guide tube sheet 107 and communicates with the guide gap. The extended part is a solid plate. The inner gas chamber is a gas distribution chamber 105, and the outer gas chamber is a gas collection chamber 104. The gas collection chamber 104 is connected to the reaction product outlet 109 on the reactor shell 101. The two ends of the gas collection chamber 104 are the inner tube sheets 106.

[0039] In the methanol synthesis reactor of this embodiment, the feed gas enters the inlet chamber formed by the reactor shell 101 and the outer tube sheet 111 from the reactor inlet 108. It passes through the main catalyst bed 102 through the heat exchange tube bundle 103 fixed on the outer tube sheet 111, flows out from the inner tube sheet 106 at the other end and enters the tube sheet gap. It then passes through the guide tube sheet 107 and enters the guide gap. It enters the gas distribution chamber 105 located in the middle and communicates with the guide gap. It then passes through the main catalyst bed 102 and reaches the gas collection chamber 104, and is discharged from the reaction product outlet 109.

[0040] Example 2 This embodiment provides a methanol synthesis reactor, such as Figure 3 As shown, the difference between this reactor and the methanol synthesis reactor in Example 1 is that the positions of the gas distribution chamber 105 and the gas collection chamber 104 are different.

[0041] The outer gas chamber is a gas distribution chamber 105, which extends from the inner tube sheet 106 to the flow guide tube sheet 107 and communicates with the flow guide gap. The extended part is a solid plate. The inner gas chamber is a gas collecting chamber 104, which has one end in the inner tube sheet 106 and the other end passing through the inner tube sheet 106, the flow guide tube sheet 107, and the outer tube sheet 111, extending to the reactor shell 101 and communicating with the reaction product outlet 109. The extended part is a solid plate.

[0042] In the methanol synthesis reactor of this embodiment, the feed gas enters the inlet chamber formed by the reactor shell 101 and the outer tube sheet 111 from the reactor inlet 108. It passes through the main catalyst bed 102 through the heat exchange tube bundle 103 fixed on the outer tube sheet 111, flows out from the inner tube sheet 106 at the other end and enters the tube sheet gap. It then passes through the guide tube sheet 107 and enters the guide gap. It enters the gas distribution chamber 105 located on the periphery and communicates with the guide gap. It then passes through the main catalyst bed 102 and reaches the gas collection chamber 104, and is discharged from the reaction product outlet 109.

[0043] Example 3 This embodiment provides a system for producing methanol by carbon dioxide hydrogenation, such as... Figure 1 As shown, the reactor used is the methanol synthesis reactor 100 described in Example 1, and its structural composition is as follows: It includes a methanol synthesis reactor 100, a gas-liquid separator 400, a distillation unit 600, and a circulating compressor 500. The methanol synthesis reactor 100 is a thermally coupled reactor, such as... Figure 2 As shown, its shell 101 is made of stainless steel, and a main catalyst bed 102 is arranged axially inside. Heat exchange tube bundles 103 (accounting for 45% of the volume in the main catalyst bed 102) are uniformly embedded within the bed. Inner tube sheets 106 and outer tube sheets 111 are respectively arranged at both ends of the heat exchange tube bundle. A tube sheet gap of a predetermined height exists between the inner tube sheet 106 and the outer tube sheet 111, and this gap is filled with a pre-reaction catalyst bed 112. The pre-reaction catalyst is a molybdenum carbide-based catalyst. The main catalyst bed 102 is filled with a copper-based catalyst.

[0044] The heat exchange tube bundle 103 is divided into a first group of heat exchange tubes and a second group of heat exchange tubes, with 50 tubes in each group. One end of the first group of heat exchange tubes is fixed to the outer tube sheet 111 at the upper end of the reactor, and the other end is fixed to the inner tube sheet 106 at the lower end of the reactor; one end of the second group of heat exchange tubes is fixed to the inner tube sheet 106 at the upper end of the reactor, and the other end is fixed to the outer tube sheet 111 at the lower end of the reactor. The fixed positions of the two groups of heat exchange tubes on the tube sheets at both ends are staggered to ensure the uniformity of fluid distribution.

[0045] A flow guide plate 107 is also provided between the inner tube sheet 106 and the outer tube sheet 111. The pre-reaction catalyst bed 112 is filled between the inner tube sheet 106 and the flow guide plate 112, and a flow guide gap with a height of 50 mm is formed between the flow guide plate 112 and the outer tube sheet 111. The setting of this flow guide gap can significantly improve the uniformity and controllability of the flow field and temperature field in the reactor, and avoid the formation of local hot spots or dead zones.

[0046] A gas distribution chamber 105 is located on the inner axis of the main catalyst bed 102 in the reactor, and a gas collection chamber 104 is located in the annular gap on the outer side of the main catalyst bed 102. The main catalyst bed 102 is separated from the gas distribution chamber 105 and the gas collection chamber 104 by a wire mesh 110 to ensure uniform distribution of the process medium flowing through the main catalyst bed 102 and to prevent catalyst powder from entering the gas chamber. Reactor inlets 108 are located at both ends of the reactor, and a reaction product outlet 109 is located outside the gas collection chamber 104.

[0047] The inlet of the heat exchange tubes on the outer tube sheet 111 is connected to the reactor feed port 108 via the reactor head, for introducing feed gas containing carbon dioxide and hydrogen. The outlet of the heat exchange tubes on the inner tube sheet 106 is connected to the gas distribution chamber via the tube sheet gaps, so that the preheated feed gas enters the main catalyst bed 102 uniformly after passing through the pre-reaction catalyst bed 112. The gas collection chamber 104 is connected to the reaction product outlet 109. The flow direction of the process medium in the methanol synthesis reactor 100 is as follows: Figure 2 As shown by the arrow in the image.

[0048] The reaction product outlet 109 is connected to the hot end inlet of the reboiler 200 in the distillation column, and the hot end outlet of the reboiler 200 is connected to the inlet of the gas-liquid separator 400. The liquid phase outlet of the gas-liquid separator 400 is connected to the middle feed inlet of the distillation column, and the gas phase outlet of the gas-liquid separator 400 is connected to the inlet of the circulating compressor 500. The outlet of the circulating compressor 500 is connected to the fresh hydrogen and carbon dioxide feed lines via pipelines and then connected to the feed inlets 108 at both ends of the reactor.

[0049] In this embodiment, the heat exchange tube bundle 103 adopts a spiral groove tube to enhance the heat transfer effect, improve the heat exchange efficiency, and reduce the bed pressure drop.

[0050] A chemical plant uses the aforementioned system for a carbon dioxide hydrogenation to methanol process. The specific operating steps are as follows: (a) A mixed feed gas containing carbon dioxide and hydrogen (volume ratio H2:CO2=3:1) simultaneously enters the methanol synthesis reactor 100 through inlets 108 at both ends of the reactor, with the operating pressure controlled at 5.0 MPa. The feed gas first enters the heat exchange tube bundle 103 (spiral groove tube) through the port on the outer tube sheet 111, and is heated to about 180°C by the heat of reaction released from the main catalyst bed 102 (copper-based catalyst, reaction temperature about 250°C) outside the tube during its flow. The preheated feed gas flows out of the heat exchange tube bundle 103 through the port on the inner tube sheet 106, and then enters the pre-reaction catalyst bed 112 (molybdenum carbide-based catalyst) in the tube sheet gap, where a partial pre-hydrogenation reaction occurs to generate methanol and active intermediates. The pre-reacted material enters the gas distribution chamber 105 through the guide gap between the guide tube sheet 107 and the outer tube sheet 111, and then enters the main catalyst bed 102 evenly through the wire mesh 110 for deep hydrogenation reaction. The methanol-containing products generated in the reaction pass through the main catalyst bed 102 and enter the gas collection chamber 104, where they are collected and finally flow out of the reactor through the reaction product outlet 109. Measurements show that the pressure drop of the main catalyst bed 102 is 30 kPa, lower than the design requirement of 50 kPa, and the maximum radial temperature difference of the bed is less than 7℃, indicating uniform temperature distribution.

[0051] (b) The reaction product obtained in step (a) (temperature about 240°C) is used as a heat source and passed into the reboiler 200 of the distillation unit for heat exchange, providing heat for the distillation process. The reaction product itself cools down to about 120°C and then flows out of the reboiler 200.

[0052] (c) The cooled process stream (approximately 120°C) obtained in step (b) is air-cooled and then fed into a gas-liquid separator 400 for gas-liquid separation, with the operating temperature controlled at 85°C. A liquid phase rich in methanol and a gas phase rich in unreacted hydrogen and carbon dioxide are obtained. Analysis shows that the methanol content in the liquid phase is approximately 62 wt%.

[0053] (d) The gas phase obtained in step (c) (mainly H2, CO2 and a small amount of CO, CH4, etc.) is pressurized to 5.2 MPa by a circulating compressor 500, mixed with fresh hydrogen and carbon dioxide feed gas, and returned to step (a) for reaction.

[0054] (e) The liquid phase obtained in step (c) is sent to the distillation unit 600 for separation to obtain refined methanol product (purity 99.5 wt%) and by-product fusel oil, and process tail gas and process wastewater are generated.

[0055] Example 4 This embodiment is an optimization of Embodiment 1, using the methanol synthesis reactor 100 of Embodiment 2. Specifically, the internal design of the methanol synthesis reactor 100 is changed by swapping the positions of the gas distribution chamber 104 and the gas collection chamber 104 from Embodiment 1. The gas collection chamber 104 is located inside the main catalyst bed 102, while the gas distribution chamber 105 is located on the outside. The reaction product outlet 109 is relocated to one end of the methanol synthesis reactor 100. The flow direction of the process medium within the methanol synthesis reactor 100 is as follows: Figure 3 As shown by the arrow in the image. When using Figure 3 When the internal gas collecting chamber and external gas distribution chamber structure shown is used, the reaction products can enter the gas collecting chamber and exit the reactor more quickly after leaving the bed, which can effectively suppress the back mixing of high-temperature products and is particularly suitable for high exothermic reaction scenarios.

[0056] A waste heat recovery unit 300 is also installed between the reboiler 200 and the gas-liquid separator 400, such as Figure 4 As shown, the hot-end inlet of the waste heat recovery unit 300 is connected to the hot-end outlet of the reboiler 200, and the hot-end outlet of the waste heat recovery unit 300 is connected to the inlet of the gas-liquid separator 400. Simultaneously, the cold-end inlet of the waste heat recovery unit 300 is used to introduce fresh hydrogen and carbon dioxide feedstock to be preheated, and the cold-end outlet is connected to the compressor 500 outlet pipeline and then to the feed inlets 108 at both ends of the reactor. By setting up the waste heat recovery unit, the residual heat of the reboiler outlet stream can be further recovered for preheating fresh feedstock gas, further improving the energy recovery rate and reducing the overall system energy consumption.

[0057] The remaining structure is the same as in Example 3.

[0058] A chemical plant uses the aforementioned system for a carbon dioxide hydrogenation to methanol process. The specific operating steps are as follows: (a) A mixed feed gas containing carbon dioxide and hydrogen (volume ratio H2:CO2=3:1) simultaneously enters the methanol synthesis reactor 100 through inlets 108 at both ends of the reactor, with the operating pressure controlled at 8.0 MPa. The feed gas first enters the heat exchange tube bundle 103 (spiral groove tube) through the port on the outer tube sheet 111. During its flow inside the tube, it is heated to approximately 220°C by the heat of reaction released from the main catalyst bed 102 (copper-based-zirconium-based composite catalyst, reaction temperature approximately 280°C). The preheated feed gas flows out of the heat exchange tube bundle 103 through the port on the inner tube sheet 106 and then enters the pre-reaction catalyst bed 112 (molybdenum sulfide-based catalyst) in the tube sheet gap. In this region, a partial pre-hydrogenation reaction occurs, generating methanol and active intermediates. The pre-reacted material enters the gas distribution chamber 105 through the guide gap between the guide tube sheet 107 and the outer tube sheet 111, and then uniformly enters the main catalyst bed 102 through the wire mesh 110 for deep hydrogenation reaction. The methanol-containing products generated by the reaction pass through the main catalyst bed 102 and enter the gas collection chamber 104, where they are collected and finally flow out of the reactor through the reaction product outlet 109. Measurements show that the pressure drop of the main catalyst bed 102 is 25 kPa, lower than the design requirement of 50 kPa, the maximum radial temperature difference of the bed is less than 5℃, and the temperature distribution is uniform.

[0059] (b) The reaction product obtained in step (a) (temperature about 272°C) is used as a heat source and passed into the reboiler 200 of the distillation unit 600 for heat exchange, providing heat for the distillation process. The reaction product itself cools down to about 150°C and then flows out of the reboiler 200.

[0060] (c) The cooled process stream (approximately 150°C) obtained in step (b) is fed into the waste heat recovery unit 300, where it undergoes countercurrent heat exchange with fresh hydrogen and carbon dioxide feed gas (approximately 25°C) to be preheated. The process stream is further cooled to approximately 80°C, and the fresh feed gas is preheated to approximately 120°C before being mixed with the recirculated gas from the outlet of the recirculating compressor 500 and entering the methanol synthesis reactor 100.

[0061] (d) The process stream (approximately 80°C) from the outlet of the waste heat recovery unit 300 obtained in step (c) is fed into the gas-liquid separator 400 for gas-liquid separation, with the operating temperature controlled at 80°C. A liquid phase rich in methanol and a gas phase rich in unreacted hydrogen and carbon dioxide are obtained. Analysis shows that the methanol content in the liquid phase is approximately 64 wt%.

[0062] (e) The gas phase obtained in step (d) (mainly H2, CO2 and a small amount of CO, CH4, etc.) is pressurized to 8.2 MPa by a circulating compressor 500 and then mixed with preheated fresh hydrogen and carbon dioxide feed gas, and returned to step (a) for reaction.

[0063] (f) The liquid phase obtained in step (d) is sent to the distillation unit 600 for separation to obtain refined methanol product (purity 99.5 wt%) and by-product fusel oil, and process tail gas and process wastewater are generated.

[0064] Comparative Example 1 A conventional steam drum-heated fixed-bed methanol synthesis reactor was used. Copper-based catalyst was loaded into the reactor feed-side head and tube side, with the catalyst bed at the head serving as the pre-reaction zone and the catalyst bed in the tube side as the main reaction zone. The reactor shell side was heated by a steam drum, and the byproduct medium-pressure steam was used to heat the reboiler in the distillation unit. The high-temperature reaction products were used as a heat source to preheat the reactor feed. The remaining process was the same as in Example 1.

[0065] Comparative Example 2 A conventional air-cooled fixed-bed methanol synthesis reactor was used. The reactor feed-side head and tube side were filled with copper-based catalyst, with the catalyst bed at the head serving as the pre-reaction zone and the catalyst bed in the tube side serving as the main reaction zone. The reactants first entered the reactor shell side, where they were preheated by the heat of reaction released from the catalyst bed in the tube side during their flow. Everything else was the same as in Example 2.

[0066] Comparative Example 3 The reactor used in this comparative example is basically the same as that in Example 3, except that the reactants flow unidirectionally within the heat exchange tube bundle 103. That is, both sets of heat exchange tube bundles 103 are fixed on the outer tube sheet 111 at one end of the main catalyst bed 102 (this end is a single tube sheet structure, without inner tube sheet 106, flow guide tube sheet 107 and pre-reaction catalyst bed 112) and the inner tube sheet 106 at the other end of the main catalyst bed 102. The gas enters the heat exchange tube bundle 103 from one end of the single tube sheet structure, and then enters the gas distribution chamber 105 through the pre-reaction catalyst bed 112 (tube sheet gap) and flow guide gap at the other end.

[0067] Comparative Example 4 The reactor used in this comparative example is basically the same as that in Example 3, except that there is no flow guide gap, that is, there are no flow guide tube plates 107 at both ends of the main catalyst bed 102, the pre-reaction catalyst bed 112 is filled in the tube plate gap between the inner tube plate 106 and the outer tube plate 111, and the part of the gas distribution chamber 105 extending from the inner tube plate 106 to the outer tube plate 111 is also a screen. After passing through the pre-reaction catalyst bed 112, the gas directly enters the gas distribution chamber 105 through the screen 110 from the contact surface between the tube plate gap and the gas distribution chamber 105.

[0068] The running results of the above embodiments and comparative examples are shown in Table 1 below: Table 1

[0069] The results show that, using the system and process of this embodiment, the reaction heat utilization rate is much higher than that of Comparative Example 1 because the reaction heat released from the main catalyst bed is used in situ to preheat the reactor feed. Although Comparative Example 2 also utilizes reaction heat to preheat the feed, and although shell-side heat transfer can be enhanced by means of baffles, the shell-side heat removal efficiency is low due to the mismatch between heat transfer and the reaction process along the axial direction and the difficulty in control. Consequently, the overall reaction heat utilization efficiency is much lower than that of Examples 3 or 4. This invention, by setting up a double or triple tube sheet, divides the heat exchange tube bundle into two groups and arranges them in a staggered tube sheet configuration at both ends of the reactor, achieving precise control of the main catalyst bed temperature. This results in a significantly lower maximum bed temperature difference in Examples 1 or 2 compared to Comparative Examples 1 or 2.

[0070] Conventional reactors, represented by Comparative Examples 1 or 2, typically do not have a pre-reaction catalyst bed or only have one at the reactor inlet end cap. The uneven flow field of the process medium through the pre-reaction catalyst bed leads to unsuitable temperatures for the medium entering the main catalyst bed. When the temperature is too low (as in Comparative Example 1), the single-pass conversion rate of carbon dioxide is low, resulting in low reaction efficiency. When the temperature is too high (as in Comparative Example 2), although it helps improve the single-pass conversion rate of carbon dioxide, it exacerbates side reactions, reduces the overall selectivity of methanol, and significantly reduces catalyst lifetime. This invention, through a unique dual-tube sheet or triple-tube sheet design and optimal matching of the pre-reaction catalyst bed and the main reaction catalyst bed, effectively controls the medium entering the main catalyst bed under optimal process conditions, achieving simultaneous improvements in single-pass conversion rate of carbon dioxide, overall selectivity of methanol, and catalyst lifetime. Furthermore, as shown in the table, the radial bed design used in this application results in a pressure drop in the main catalyst bed that is only 1 / 10 or even lower than that in Comparative Examples 1 or 2. This has unpredictable technical effects on reducing the energy consumption of the circulating compressor and enabling large-scale production.

[0071] Comparative Examples 3 and 4 exhibit main catalyst bed pressure drop and reaction heat utilization efficiency comparable to Examples 3 and 4. However, in Comparative Example 3, because all reactants flow "unidirectionally" from one end of the heat exchange tube bundle to the other, the temperature of the reactants gradually increases as they are heated by the reaction heat released from the main catalyst bed. Consequently, the heat exchange temperature difference between the reactants and the main catalyst bed gradually decreases, resulting in a decrease in the heat removal efficiency of the heat exchange tube bundle on the main catalyst bed near its outlet end. This leads to an excessively large temperature difference in the main catalyst bed along the reactor axis, resulting in a low single-pass carbon dioxide conversion rate, a short catalyst lifetime, and lower methanol selectivity compared to Examples 3 and 4. In Comparative Example 4, due to the absence of a flow guide plate and flow guide gap, the path length (equivalent to residence time) of the reactants flowing through the pre-reaction catalyst bed before entering the gas collection chamber varies from heat exchange tube bundle to heat exchange tube bundle. As a result, the degree of pre-reaction also varies. At the same time, the different flow paths also mean different flow resistance, leading to uneven flow rates of reactants in different heat exchange tubes. This, in turn, results in uneven heat removal efficiency of the heat exchange tube bundle on the main catalyst bed, which in turn causes a large temperature difference and short lifespan of the main catalyst bed, as well as low single-pass conversion rate of carbon dioxide and total selectivity of methanol.

[0072] In summary, the system and process of this invention have good prospects for industrial application.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to the above embodiments without departing from the technical principles of the present invention, and these should all be considered within the scope of protection of the present invention.

Claims

1. A methanol synthesis reactor, characterized in that, It includes a reactor shell (101), a main catalyst bed (102) disposed inside the reactor shell (101), reactor inlets (108) located at both ends of the reactor shell (101), and a reaction product outlet (109) provided on the reactor shell (101). A heat exchange tube bundle (103) is embedded in the main catalyst bed (102). Both ends of the main catalyst bed (102) are provided with an inner tube sheet (106), a flow guide tube sheet (107), and an outer tube sheet (111) in sequence. The main catalyst bed (102) is located between the inner tube sheets (106). A tube sheet gap is formed between the inner tube sheet (106) and the flow guide tube sheet (107). The tube sheet gap is filled with a pre-reacted catalyst bed (112). A flow guide gap is formed between the flow guide tube sheet (107) and the outer tube sheet (111). The tube sheet gap and the flow guide gap are connected through the flow guide tube sheet (107). The heat exchange tube bundle (103) is divided into a first group of heat exchange tubes and a second group of heat exchange tubes. One end of the first group of heat exchange tubes is fixed on the outer tube sheet (111) at one end of the main catalyst bed (102) and the inner tube sheet (106) at the other end of the main catalyst bed (102). The second group of heat exchange tubes is the opposite of the first group of heat exchange tubes, with one end fixed on the inner tube sheet (106) at one end of the main catalyst bed (102) and the outer tube sheet (111) at the other end of the main catalyst bed (102). The heat exchange tubes fixed on the inner tube sheet (106) are connected to the tube sheet on the same side of the inner tube sheet. The main catalyst bed (102) is provided with screens (110) on both the inner and outer sides. The inner screen forms an inner gas chamber, and the outer screen and the reactor shell (101) form an outer gas chamber. The inner and outer screens extend to the inner tube sheets (106) on both sides. The main catalyst bed (102) is located in the space formed by the inner screen, the outer screen and the inner tube sheet (106). When the inner gas chamber is a gas distribution chamber (105), the inner gas chamber extends from the inner tube sheet (106) to the guide tube sheet (107) and communicates with the guide gap. The extended part is a solid plate. The outer gas chamber is a gas collection chamber (104). The gas collection chamber (104) is connected to the reaction product outlet (109) on the reactor shell (101). The two ends of the gas collection chamber (104) are the inner tube sheet (106). When the outer gas chamber is a gas distribution chamber (105), the outer gas chamber extends from the inner tube sheet (106) to the flow guide tube sheet (107) and communicates with the flow guide gap. The extended part is a solid plate. The inner gas chamber is a gas collection chamber (104). One end of the gas collection chamber (104) is the inner tube sheet (106), and the other end passes through the inner tube sheet (106), the flow guide tube sheet (107), and the outer tube sheet (111) and extends to the reactor shell (101) and communicates with the reaction product outlet (109). The extended part is a solid plate.

2. The methanol synthesis reactor according to claim 1, characterized in that, The raw material gas enters the inlet chamber formed by the reactor shell (101) and the outer tube sheet (111) from the reactor inlet (108). It passes through the main catalyst bed (102) through the heat exchange tube bundle (103) fixed on the outer tube sheet (111), flows out from the inner tube sheet (106) at the other end into the tube sheet gap, passes through the guide tube sheet (107) into the guide gap, enters the gas distribution chamber (105) connected to the guide gap, passes through the main catalyst bed (102) to reach the gas collection chamber (104), and is discharged from the reaction product outlet (109).

3. The methanol synthesis reactor according to claim 1, characterized in that, The two sets of heat exchange tubes are arranged in a staggered manner on the fixed positions of the outer tube sheets (111) at both ends; And / or, the heat exchange tube bundle (103) is an enhanced heat transfer tube, which is selected from one or more of the following: nail-head tube, spiral groove tube, cross-grooved tube, tapered tube, or finned tube.

4. The methanol synthesis reactor according to claim 1, characterized in that, The activation temperature of the catalyst used in the pre-reaction catalyst bed (102) is 60-90℃ lower than that of the catalyst used in the main catalyst bed (102).

5. A system for producing methanol by carbon dioxide hydrogenation, characterized in that, It includes, in sequence, a methanol synthesis reactor (100), a distillation unit reboiler (200), a gas-liquid separator (400), and a distillation unit (600) as described in claim 1. The distillation unit reboiler (200) is provided with a hot end inlet and a hot end outlet. The reaction product outlet (109) of methanol synthesis (100) is connected to the hot end inlet of the distillation unit reboiler (200). The inlet of the gas-liquid separator (400) is connected to the hot end outlet of the distillation unit reboiler (200). The gas-liquid separator (400) is equipped with a liquid phase outlet and a gas phase outlet; The liquid phase outlet is connected to the feed inlet of the distillation unit (600).

6. The carbon dioxide hydrogenation to methanol system according to claim 5, characterized in that, The gas phase outlet of the gas-liquid separator (400) is connected to the reactor inlet (108) of the methanol synthesis reactor (100); a circulating compressor (500) is provided on the gas phase outlet connecting pipeline of the gas-liquid separator (400).

7. The carbon dioxide hydrogenation to methanol system according to claim 5, characterized in that, A waste heat recovery unit (300) is provided between the reboiler (200) of the distillation unit and the gas-liquid separator (400); the hot end inlet of the waste heat recovery unit (300) is connected to the hot end outlet of the reboiler (200) of the distillation unit, and the hot end outlet of the waste heat recovery unit (300) is connected to the inlet of the gas-liquid separator (400). The methanol synthesis reactor (100) has an inlet (108) connected to an air inlet pipe, which is preheated by a waste heat recovery unit (300).

8. A process for producing methanol by carbon dioxide hydrogenation, characterized in that, The carbon dioxide hydrogenation to methanol system as described in claim 5 includes the following steps: (a) The raw material gas enters the inlet chamber formed by the reactor shell (101) and the outer tube sheet (111) through the reactor inlet (108), passes through the main catalyst bed (102) through the heat exchange tube bundle (103) fixed on the outer tube sheet (111), and is heated by the main catalyst bed outside the tube. It flows out from the inner tube sheet (106) at the other end and enters the tube sheet gap. A pre-hydrogenation reaction occurs in the pre-reaction catalyst bed. The reaction product then passes through the guide tube sheet (107) and enters the guide gap. After being mixed evenly, it enters the gas distribution chamber (105) connected to the guide gap. Then, it passes through the screen (110) and enters the main catalyst bed (102) for a hydrogenation reaction. The reaction product containing methanol reaches the gas collection chamber (104) through the screen and flows out of the methanol synthesis reactor (100) from the reaction product outlet (109). (b) The reaction product obtained in step (a) is used as a heat source and passed into the reboiler (200) of the distillation unit for heat exchange. After cooling, the cooled process stream is obtained. (c) The cooled process stream obtained in step (b) is fed into the gas-liquid separator (400) for gas-liquid separation to obtain a liquid phase rich in methanol and a gas phase rich in unreacted hydrogen and carbon dioxide; (d) The gas phase obtained in step (c) is pressurized by a circulating compressor and mixed with the replenished fresh hydrogen and carbon dioxide feed gas, and then returned to step (a) for reaction; (e) The liquid phase obtained in step (c) is sent to a distillation unit (600) for separation to obtain refined methanol product and by-product fusel oil.

9. The carbon dioxide hydrogenation to methanol system according to claim 8, characterized in that, In step (b), the temperature is lowered to 110-130℃ to obtain the cooled process stream; And / or, in step (c), the operating temperature for gas-liquid separation is 50°C to 95°C; And / or, in step (a), the operating pressure of the methanol synthesis reactor is 2.0 MPa to 8.0 MPa, the pressure drop of the main catalyst bed is not higher than 0.05 MPa, and the maximum radial temperature difference of the bed is less than 7°C.

10. The carbon dioxide hydrogenation to methanol system according to claim 8, characterized in that, A waste heat recovery unit (300) is provided between the reboiler (200) of the distillation unit and the gas-liquid separator (400); the hot end inlet of the waste heat recovery unit (300) is connected to the hot end outlet of the reboiler (200) of the distillation unit, and the hot end outlet of the waste heat recovery unit (300) is connected to the inlet of the gas-liquid separator (400); in step (b), after the reaction product enters the reboiler (200) of the distillation unit, it also enters the waste heat recovery unit (300) to exchange heat with the fresh hydrogen and carbon dioxide feed gas to be preheated.

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