Two-channel isothermal coupling adiabatic CO2 hydrogenation methanol preparation system

Abstract

The utility model provides a two-channel isothermal coupling adiabatic CO2 hydrogenation methanol preparation system, and belongs to the technical field of methanol preparation. The system comprises a methanol synthesis reactor, a steam superheater, a water cooler and a gas-liquid separation tank, wherein the methanol synthesis reactor is a dual-channel isothermal coupling adiabatic reactor. Raw material gas compressed to system pressure is subjected to synthesis gas preheating, reaction heat is used for heating to a catalyst activation temperature, then methanol synthesis reaction is carried out, obtained methanol synthesis gas is subjected to gas-liquid separation after heat exchange, obtained gas phase is compressed to system pressure and then recycled, obtained liquid phase is subjected to methanol rectification, and a product methanol is obtained. The utility model provides a system for preparing methanol by CO2 hydrogenation, which can flexibly cope with working conditions such as driving, load change and the like, and is convenient to operate and low in investment cost.

Description

Technical Field

[0001] The utility model relates to the technical field of methanol preparation, in particular to a dual-channel isothermal coupled adiabatic CO2 hydrogenation system for preparing methanol. Background Art

[0002] In response to carbon neutrality, the resource utilization of carbon dioxide has become a hot topic of research. Methanol is a basic organic chemical raw material with a simple structure and a wide range of applications. Producing methanol through the hydrogenation of carbon dioxide is relatively easy to implement based on the reaction principle. It has significant implications for green and sustainable development and contributes to the achievement of the dual carbon goals.

[0003] The main problems of CO2 hydrogenation to methanol process at present are as follows: (1) There are many equipments, long routes and large investment. A raw gas heater is required, the temperature difference of the heat exchanger tube sheet is large, and it is easy to leak. There are multiple coolers at the outlet of the methanol synthesis process reactor, and the process is complicated. (2) High energy consumption and poor economic efficiency. The biggest factor restricting the application of CO2 hydrogenation to methanol process is the economic efficiency of the device. In the conventional process, an additional heat source needs to be introduced to heat the raw gas to the activation temperature, which increases the cost of equipment and pipelines, high energy consumption and poor economic efficiency of the device. (3) The methanol synthesis device can only produce saturated steam as a by-product, which has low utilization value and cannot be transported over long distances.

[0004] Traditional mainstream methanol synthesis reactors are broadly categorized as axial and radial. Axial reactors are simple in structure, easy to operate, and utilize reaction heat to meet reaction temperature requirements. They also produce higher steam pressure and smaller temperature differences across the catalyst bed. However, axial reactors, in which the catalyst is loaded into the tubes, are not only inconvenient to maintain but also have a low volumetric efficiency. This results in larger equipment for the same production capacity and higher manufacturing costs. While radial reactors offer larger catalyst loadings and lower radial flow resistance, they suffer from large temperature differences across the catalyst bed, leading to uneven gas distribution across the catalyst bed and reduced catalyst contact efficiency.

[0005] CN115259997A provides a self-heating carbon dioxide hydrogenation methanol synthesis process. This process utilizes heat generated by the catalyst bed, allowing the mixed feed gas to enter the reactor only after being preheated to 140-180°C in a preheater, eliminating the need for continuous preheating to the methanol synthesis catalyst activation temperature. Compared to conventional methanol synthesis processes, this significantly reduces the heat load of the preheater, and the preheater has a small heat exchange area, resulting in low equipment investment. The synthesis gas from the self-heating reactor is first recycled through a waste heat boiler before entering the preheater to preheat the mixed feed gas, improving the heat recovery level and the overall heat recovery efficiency of the entire device. While this process is energy-efficient, it still requires a feed gas preheater, resulting in a complex process and high equipment investment. Utility Model Content

[0006] In the process of producing methanol from synthesis gas, the reactor outlet gas needs to be transported to the feed heater to preheat the inlet gas to the catalyst activation temperature. After passing through the feed heater, the heat grade of the reactor outlet gas becomes low and can no longer be used for the effective recovery of by-product steam, resulting in low thermal efficiency of the device. In addition, traditional methanol synthesis processes mostly use shell-and-tube water-cooled isothermal reactors. The catalyst is loaded in a shell-and-tube fixed bed. The boiler water in the shell side removes the reaction heat and produces high-pressure saturated steam. The reaction temperature is controlled by the pressure of boiling water in the shell side. The temperatures of different catalyst beds in this type of reactor are basically the same. The saturated steam produced is prone to condensation due to temperature drop during transportation in the pipeline network. Moreover, the temperature control by boiling water pressure is indirect control, which has control lag and can easily lead to reactor collapse and overheating problems.

[0007] The technical problem to be solved by the present invention is to provide a simplified CO2 hydrogenation to methanol system and process based on the status of the existing technology, which can flexibly respond to working conditions such as start-up and load changes, fully utilize the reaction waste heat, is easy to operate, and has low investment cost.

[0008] According to one aspect of the present invention, a dual-channel isothermal coupled adiabatic CO2 hydrogenation system for producing methanol is provided, comprising a methanol synthesis reactor, a steam superheater, a water cooler and a gas-liquid separation tank;

[0009] The methanol synthesis reactor is a dual-channel isothermal coupled adiabatic reactor;

[0010] The dual-channel isothermal coupled adiabatic reactor comprises a cylinder, the top of which is provided with a syngas main inlet, a syngas preheating outlet, and a high-pressure saturated steam outlet, and the bottom of which is provided with a methanol syngas outlet; the cylinder is divided into an isothermal section and an adiabatic section from top to bottom; a syngas side inlet is provided between the isothermal section and the adiabatic section; a high-pressure boiler water inlet and a syngas preheating inlet are provided on the cylinder of the isothermal section near the syngas side inlet; the high-pressure boiler water inlet is connected to the high-pressure saturated steam outlet after passing through the isothermal section; and the syngas preheating inlet is connected to the syngas preheating outlet after passing through the isothermal section;

[0011] The methanol synthesis gas outlet at the bottom of the methanol synthesis reactor passes through the steam superheater and the water cooler in sequence and is communicated with the side inlet of the gas-liquid separation tank.

[0012] Optionally, the isothermal section is provided with a catalyst cylinder I, which is sleeved inside the cylinder and forms a gap I with the inner wall of the cylinder, wherein the gap I forms a gas channel I connected to the main inlet of the synthesis gas; a plurality of external air inlet annular gaps I are provided on the side wall of the catalyst cylinder I;

[0013] The catalyst cylinder I is sheathed with a central tube I, the upper end of the central tube I is closed, and the lower end is connected to the thermal insulation section; a plurality of inner air intake annular gaps I are provided on the side wall of the central tube I;

[0014] The reaction zone I is located between the catalyst cylinder I and the central tube I.

[0015] Optionally, the synthesis gas preheating outlet is communicated with the gap I, that is, the synthesis gas preheating outlet is located inside the reactor, and the preheated synthesis gas does not discharge out of the reactor through the synthesis gas preheating outlet, but directly enters the gap I.

[0016] Optionally, the isothermal section is provided with a catalyst cylinder II, which is sleeved inside the cylinder and forms a gap II with the inner wall of the cylinder, wherein the gap II forms a gas channel II communicating with the adiabatic section; a plurality of inner air intake annular gaps II are provided on the side wall of the catalyst cylinder II;

[0017] The catalyst cylinder II is provided with a central tube II, the upper end of the central tube II is connected to the main inlet of the synthesis gas, and the lower end is closed; a plurality of external air inlet annular gaps II are provided on the side wall of the central tube II;

[0018] The reaction zone II is located between the catalyst cylinder II and the central tube II.

[0019] Optionally, multiple plate heat exchange modules are independently provided in the reaction zone I and the reaction zone II, and the plate heat exchange modules are radially arranged with the central tube I or the central tube II as the center; the inlet of the plate heat exchange module is connected to the refrigerant input pipe, and the outlet of the plate heat exchange module is connected to the refrigerant output pipe.

[0020] Optionally, a plurality of protrusions are provided on the side surface of the plate heat exchange module.

[0021] Optionally, the plate heat exchange module includes a high-pressure boiler water channel and a synthesis gas preheating channel; the refrigerant input pipeline includes a high-pressure boiler water riser and a synthesis gas riser; the refrigerant output pipeline includes a high-pressure saturated steam riser and a preheated synthesis gas riser;

[0022] The high-pressure boiler water riser is connected to the high-pressure saturated steam riser through the high-pressure boiler water channel, and the high-pressure saturated steam riser is connected to the high-pressure saturated steam outlet; the synthesis gas riser is connected to the preheated synthesis gas riser through the synthesis gas preheating channel, and the preheated synthesis gas riser is connected to the synthesis gas preheating outlet.

[0023] Optionally, the inlet of the high-pressure boiler water channel is connected to multiple high-pressure boiler water riser pipes, the multiple high-pressure boiler water riser pipes are gathered and connected to a high-pressure boiler water collecting ball, and the high-pressure boiler water collecting ball is connected to the high-pressure boiler water inlet; the outlet of the high-pressure boiler water channel is connected to multiple high-pressure saturated steam riser pipes, the multiple high-pressure saturated steam riser pipes are gathered in a high-pressure saturated steam collecting ring, and the high-pressure saturated steam collecting ring is connected to the high-pressure saturated steam outlet.

[0024] Optionally, the inlet of the synthesis gas preheating channel is connected to multiple synthesis gas risers, and the multiple synthesis gas risers are converged and connected to the synthesis gas collecting annulus, and the synthesis gas collecting annulus is connected to the synthesis gas preheating inlet; the outlet of the synthesis gas preheating channel is connected to multiple preheating synthesis gas risers, and the multiple preheating synthesis gas risers are converged to the preheating synthesis gas collecting ring, and the preheating synthesis gas collecting ring is connected to the synthesis gas preheating outlet.

[0025] Optionally, the system further includes a steam drum for separating water vapor from the high-pressure saturated steam generated by the methanol synthesis reactor; the high-pressure saturated steam outlet is connected to the high-pressure boiler water inlet through the steam drum, and the saturated steam outlet of the steam drum is connected to the steam superheater.

[0026] Optionally, the synthesis gas side inlet is connected to a gas distributor inside the cylinder.

[0027] Optionally, a gas guide plate is provided inside the cylinder of the insulation section close to the synthesis gas inlet.

[0028] Optionally, the insulation section is provided with an axial reaction catalyst bed.

[0029] Optionally, the upper and lower end plates of the axial reaction catalyst bed are connected to the cylinder to form a cavity, which is used to fill with a high-temperature resistant catalyst, and the reaction gas passes through the upper end plate, the cavity and the lower end plate in sequence to produce an adiabatic reaction.

[0030] Optionally, the insulation section is provided with a radial reaction catalyst bed.

[0031] Optionally, the radial reaction catalyst bed is fixed to the cylinder through a bottom plate, and the bottom plate is connected to the top plate and the left and right side plates to form a cavity, which is used to fill the high-temperature resistant catalyst. The reaction gas enters the cavity through the left and right side plates to produce an adiabatic reaction.

[0032] Optionally, the radial reaction catalyst bed is provided with a central tube III, which is coaxially arranged with the central tube I or the central tube II; a plurality of vents are provided on the side wall of the central tube III; the upper port of the central tube III is closed, and the lower port is connected to the methanol synthesis gas outlet.

[0033] According to another aspect of the present invention, a dual-channel isothermal coupled adiabatic CO2 hydrogenation process for producing methanol using the above system is provided, comprising preheating the feed gas compressed to the system pressure, raising the temperature to the catalyst activation temperature using the reaction heat, and then conducting a methanol synthesis reaction;

[0034] The obtained methanol synthesis gas is subjected to gas-liquid separation after heat exchange, the obtained gas phase is compressed to system pressure and then recycled, and the obtained liquid phase is subjected to methanol distillation to obtain product methanol.

[0035] Optionally, the saturated steam produced by the methanol synthesis reaction is superheated to generate superheated steam.

[0036] Optionally, the superheat degree of the superheated steam is 1 to 100°C, preferably 50 to 80°C.

[0037] Optionally, the pressure of the saturated steam is 0.5-5.0 MPaG, preferably 2-4 MPaG.

[0038] Optionally, the CO2 molar content in the feed gas is greater than 50%, preferably greater than 90%.

[0039] Optionally, the temperature of the preheated raw gas is 150-400°C, preferably 180-350°C; the temperature of the methanol synthesis gas is 200-500°C, preferably 250-400°C.

[0040] Optionally, the gas temperature for gas-liquid separation is 30-200°C, preferably 50-100°C.

[0041] The present invention provides a simplified CO2 hydrogenation to methanol process in combination with a novel adiabatic isothermal coupling reactor. In this process, the reactor used removes the heat of reaction through radially arranged plate heat exchange modules, and catalysts are loaded between adjacent modules to ensure the heat transfer rate while increasing the volume ratio; heat is transferred through boiler water and raw gas in the isothermal section, simplifying the process flow, reducing equipment investment, and improving the economic efficiency of the device; by coupling the adiabatic section, high-temperature resistant catalysts are loaded, and the reaction exotherm is used to ensure that the outlet temperature is above 250°C, which is used to superheat saturated steam and solve the problem of difficult pipeline transportation; by setting a synthesis gas bypass inlet between the isothermal section and the adiabatic section, the reactor temperature control can be achieved more easily. After the bypass synthesis gas is mixed with the reaction gas from the isothermal section, it is heated to the activation temperature of the catalyst in the adiabatic section, and enters the high-temperature resistant catalyst bed through the gas distributor and guide plate to carry out the synthesis reaction. Adjusting the bypass flow rate can flexibly control the outlet temperature of the reaction gas.

[0042] In the present invention, the catalysts in the isothermal section and the adiabatic section have different temperature tolerances. The isothermal section can use a conventional catalyst with a maximum temperature tolerance of 350°C, while the adiabatic section can use a high-temperature resistant catalyst with a maximum temperature tolerance of 500°C.

[0043] Compared with the prior art, the utility model has the following advantages:

[0044] (1) No feed heater is required. The reaction heat is directly used in the reactor to preheat the synthesis gas to the catalyst activation temperature in the isothermal section. The reaction gas produced in the isothermal section is used to heat the bypass synthesis gas, so that the temperature of the mixed synthesis gas reaches the catalyst activation temperature in the adiabatic section. This fully utilizes the waste heat of the process gas, improves system integration, and reduces equipment investment.

[0045] (2) By setting a syngas bypass inlet, adjusting the syngas main and bypass flow ratio, and controlling the amount of fresh gas participating in the reaction in the adiabatic section, the reaction heat release and the reaction gas outlet temperature can be controlled, and flexible response can be given to start-up, load changes, and other situations.

[0046] (3) The lower part of the reactor is coupled with an insulation section, which can effectively increase the reactor outlet temperature to above 400°C. By setting a steam superheater at the reactor outlet, high-pressure saturated steam is produced by superheating, which improves the steam quality and facilitates pipeline transportation and subsequent use, thereby improving the stability of steam utilization.

[0047] (4) By setting up a high-pressure boiler water collecting ball and a syngas collecting annulus, the plate heat exchange module is divided into a water-cooling channel and an air-cooling channel in a limited space, which can effectively remove and utilize the reaction heat to preheat the syngas and produce high-pressure saturated steam.

[0048] (5) The plate heat exchange module increases the contact area and heat exchange efficiency compared with the traditional shell and tube heat exchange, and greatly increases the catalyst loading capacity.

[0049] (6) The dual-channel uses different phase media (boiler water and synthesis gas) to extract heat according to the different loading amounts of the outer and inner catalyst layers. The temperature gradient distribution is more reasonable, the equipment diameter is smaller than that of the conventional shell-and-tube methanol synthesis reactor, and the energy utilization rate is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a process flow chart of a dual-channel isothermal coupled adiabatic CO2 hydrogenation process for producing methanol as described in Example 1 of the present utility model;

[0051] Figure 2 This is a schematic diagram of the external cylinder structure of the methanol synthesis reactor of the present utility model;

[0052] Figure 3 This is a schematic diagram of the internal structure of a methanol synthesis reactor of the present invention;

[0053] Figure 4 This is another schematic diagram of the internal structure of the methanol synthesis reactor of the present invention.

[0054] Figure 5 This is a schematic diagram of a plate heat exchange module (collecting ring) including dual-channel heat exchange in the present invention;

[0055] Figure 6 This is a schematic diagram of a plate heat exchange module (collecting ball) including dual-channel heat exchange in the present invention;

[0056] Among them, a-synthesis gas compressor, b-methanol synthesis reactor, c-steam drum; d-steam superheater; e-desalted water heat exchanger; f-water cooler; g-gas-liquid separation tank; h-circulating gas compressor;

[0057] 1-Cylinder; 2-High-pressure boiler water inlet; 3-High-pressure saturated steam outlet; 4-Synthesis gas preheating outlet; 5-Synthesis gas main inlet; 6-Synthesis gas preheating inlet; 7-Main inspection port; 8-Catalyst upper discharge port; 9-Synthesis gas side inlet; 10-Catalyst lower discharge port; 11-Reaction gas outlet; 12-High-pressure saturated steam collection ring; 13-Preheated synthesis gas collection ring; 14-Preheated synthesis gas riser; 15-Heat transfer module; 16-Center pipe I / II; 17-High-pressure boiler water riser; 18-High-pressure boiler Water collecting ball; 19-synthesis gas riser; 20-synthesis gas collecting annulus; 21-isothermal section inspection port; 22-gas guide plate; 23-high-temperature resistant catalyst; 24-insulation section inspection port; 25-collecting ball inspection port; 26-gas distributor; 27-pressure grid; 28-high-pressure saturated steam riser; 29-catalyst tube; 30-ceramic ball; 31-expansion joint; 32-high-pressure boiler water channel; 33-synthesis gas preheating channel; 34-high-pressure boiler water collecting ring; 35-synthesis gas collecting ball; 36-center pipe III. DETAILED DESCRIPTION

[0058] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation to the present invention.

[0059] Example 1

[0060] like Figure 1 As shown, the raw carbon dioxide and hydrogen gases are compressed to system pressure by syngas compressor a before entering the gas cooling channel (syngas preheating channel) of methanol synthesis reactor b. The reaction heat raises the temperature to the catalyst activation temperature before re-entering the methanol synthesis reactor b for reaction. The exiting reaction gas is superheated to saturated steam by steam superheater d, then passes through desalted water heat exchanger e for heat utilization. After cooling in water cooler f, it enters gas-liquid separator g. The gas phase is compressed to system pressure by recycle gas compressor h from the top and then fed to the reactor inlet for recycling. The liquid phase flows from the bottom to the methanol distillation unit, producing methanol with a purity exceeding 99.89%.

[0061] In this example, the raw carbon dioxide and hydrogen are compressed to a system pressure of 8 MPa by a syngas compressor before being transported to a methanol synthesis reactor for preheating to the catalyst activation temperature of 210-220°C in the isothermal section. The reactor then re-enters the methanol synthesis reactor for reaction. The reactor is divided into an upper isothermal section and a lower adiabatic section. The upper isothermal section exchanges heat with boiler water in the drum to form a water-vapor mixture that flows to the top of the reactor to produce high-pressure saturated steam. The lower adiabatic section ensures that the reactor outlet temperature remains above 250°C. The reacted materials are then passed through a steam superheater and a desalted water heat exchanger for heat utilization. They are then cooled to 50°C in a water cooler before entering a separator. The unreacted syngas exits the upper section and is compressed to a system pressure of 8 MPa by a recycle gas compressor before being recycled to the reactor inlet. The crude methanol produced by the reaction is then transported from the lower section of the separator to a methanol distillation system to produce 99.89% refined methanol.

[0062] like Figure 2 、 Figure 3 As shown, the methanol synthesis reactor used in this embodiment has a vertical cylindrical shape, divided into two sections. In the upper section, the catalyst cartridge is nested within the cartridge, forming a gap between the cartridge and the cartridge. This gap connects to the main syngas inlet, forming a syngas inlet channel. A central tube I is positioned at the center of the catalyst cartridge. Its upper end is sealed, and its lower end connects to the insulation section. An inner and outer air inlet annular gaps are defined on the sidewalls of the cartridge and the catalyst cartridge, respectively. The area between the catalyst cartridge and central tube I is called the reaction zone. This zone is filled with partitioned catalyst, which can be discharged through the catalyst upper discharge port at the lower end of the reaction zone.

[0063] In order to keep the upper reaction zone in an isothermal state and preheat the synthesis gas to the catalyst activation temperature and the by-product high-pressure saturated steam, a zoned heat exchange is set up in the upper reaction zone of the reactor. Multiple plate heat exchange modules are provided in the two zones. The plate heat exchange modules are arranged in the reaction zone in a central radial manner with the central tube I as the axis. The synthesis gas is preheated in the secondary catalyst zone, and the high-pressure saturated steam is generated in the primary catalyst zone.

[0064] The plate heat exchanger in the secondary partition of the catalyst is provided with a synthesis gas preheating channel, and the plate heat exchanger in the primary partition of the catalyst is provided with a high-pressure boiler water channel. The high-pressure boiler water riser is connected to the high-pressure saturated steam riser via the high-pressure boiler water channel, and the high-pressure saturated steam riser is connected to the high-pressure saturated steam outlet; the synthesis gas riser is connected to the preheated synthesis gas riser via the synthesis gas preheating channel, and the preheated synthesis gas riser is connected to the synthesis gas preheating outlet.

[0065] like Figure 3As shown, the syngas preheating outlet is located outside the reactor. After passing through the plate heat exchange module, the preheated syngas is discharged from the reactor through the syngas preheating outlet on the top of the reactor and then enters the syngas preheating inlet. This air intake method can adjust the amount of syngas and preheated syngas, and the adjustment is flexible. The preheated syngas can also be discharged from the reactor without passing through the syngas preheating outlet (the syngas preheating outlet is located inside the reactor and is directly connected to the gap. Figure 3 Not shown), but directly enters the gap through the synthesis gas preheating outlet. This air intake method does not require the preheated synthesis gas to bypass the reactor, but the gas volume regulation performance is poor.

[0066] like Figure 5 As shown, the upper end of the high-pressure boiler water riser is connected to the high-pressure boiler water channel, and the lower end is collected in the high-pressure boiler water collection ring; the upper end of the synthesis gas riser is connected to the synthesis gas preheating channel, and the lower end is collected in the synthesis gas collection ring. In addition, the collection ring involved in the present invention can also be replaced by a collection ball, such as Figure 6 shown.

[0067] A synthesis gas side inlet is provided between the upper and lower sections of the cylinder. The synthesis gas from the bypass can be directly mixed with the methanol synthesis gas flowing out of the upper center pipe I, and then pass through the gas distributor and the gas guide plate in sequence to enter the lower adiabatic reaction section, and enter the high-temperature resistant catalyst layer in an axial flow direction to carry out the methanol synthesis reaction. The generated gas after the reaction is completed is discharged from the bottom outlet.

[0068] like Figure 3 As shown, the insulation section is provided with an axial reaction catalyst bed, and the upper and lower end plates of the axial reaction catalyst bed are connected to the cylinder to form a cavity, which is used to fill the high-temperature resistant catalyst; the reaction gas passes through the upper and lower end plates in turn to produce an adiabatic reaction.

[0069] The cylinder 1 is provided with an upper catalyst discharge port 8 for loading and unloading the catalyst in the upper isothermal reaction zone; a lower catalyst discharge port 10 is used for loading and unloading the catalyst in the lower adiabatic reaction zone. The main inspection port 7 is used by maintenance personnel to enter the interior of the reactor, and the isothermal section inspection port 21 and the adiabatic section inspection port 24 are used by maintenance personnel to repair the upper and lower areas of the reactor, respectively. Ceramic balls 30 are also arranged in the cylinder 1 to protect and support the high-temperature resistant catalyst 23 and the catalyst bed in the upper isothermal reaction zone. The pressure grid 27 is used to fix the high-temperature resistant catalyst 23 and the ceramic balls 30; the gas guide plate 22 and the gas distributor 26 are used to distribute and mix the reaction gases; each high-pressure saturated steam riser 28 and each preheated synthesis gas riser 14 are provided with an expansion joint 31 in the middle, which effectively solves the thermal expansion problem caused by temperature differences in the upper section of the reactor.

[0070] The isothermal section of the methanol synthesis reactor is filled with a low-temperature high-conversion catalyst, and the adiabatic section is filled with a high-temperature resistant catalyst.

[0071] For start-up conditions, the syngas bypass flow rate can be changed through regulation to ensure that the reactor outlet temperature is above 300°C.

[0072] In the early stages of the reaction, when catalyst activity is high and methanol synthesis is effective, the reactor may experience a temperature spike. In this case, the syngas bypass flow rate can be reduced to control the exothermic reaction in the adiabatic section, thereby reducing the temperature to normal. In the late stages of the reaction, when catalyst deactivation leads to insufficient reactor outlet temperature, the syngas bypass flow rate can be increased to raise the reactor gas outlet temperature to above 300°C.

[0073] In the event of changes in the unit load, the reactor temperature and its outlet temperature fluctuate, far exceeding or failing to meet system requirements. The temperature can be controlled by reducing or increasing the synthesis gas bypass flow rate.

[0074] Example 2

[0075] Different from Example 1, Figure 4 As shown, the methanol synthesis reactor used in this embodiment has a vertical cylindrical shape, divided into two sections. In the upper section, the catalyst cartridge is sleeved within the cartridge, forming a gap between the cartridge and the cartridge. This gap serves as the syngas outlet channel, which is connected to the insulation section. A central tube II is provided within the catalyst cartridge. The top of central tube II is connected to the main syngas inlet, extending from the main syngas inlet to the bottom of the cartridge. The bottom of central tube II is sealed. External and internal air inlet annuli are provided on the sidewalls of central tube II and the catalyst cartridge, respectively. The area between the catalyst cartridge and central tube II is called the reaction zone, where the zoned catalyst is loaded.

[0076] The gas flowing out through the synthesis gas external outlet channel is mixed with the synthesis gas entering through the synthesis gas side inlet, passes through the gas distributor and the gas guide plate in sequence, and enters the lower adiabatic reaction zone in a uniform distribution manner, and then passes through the catalyst bed in a radial manner from both sides to react. The generated methanol synthesis gas enters the central tube III of the lower section of the reactor through the vent holes on the central tube III and is collected, and then discharged through the bottom outlet.

[0077] like Figure 4 As shown, the adiabatic section is provided with a radial reaction catalyst bed, which is fixed to the cylinder through a bottom plate. The bottom plate is connected to the top plate and the left and right side plates to form a cavity, which is used to fill the high-temperature resistant catalyst; the reaction gas enters the central tube III through the left and right side plates, during which an adiabatic reaction occurs.

[0078] Any numerical value mentioned in this utility model includes all values that increase by one unit each time from the lowest value to the highest value if there is only an interval of two units between any minimum value and any maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is stated to be 50-90, it means in this specification that 51-89, 52-88... and 69-71 and 70-71 are specifically listed. For non-integer values, 0.1, 0.01, 0.001 or 0.0001 can be appropriately considered as one unit. These are just some special examples. In this application, in a similar manner, all possible combinations of numerical values between the listed lowest value and the listed highest value are considered to have been disclosed.

[0079] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as provided within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A dual-channel isothermal coupled adiabatic CO2 hydrogenation system for producing methanol, characterized in that: The system includes a methanol synthesis reactor, a steam superheater, a water cooler and a gas-liquid separation tank; The methanol synthesis reactor is a dual-channel isothermal coupled adiabatic reactor; The dual-channel isothermal coupled adiabatic reactor comprises a cylinder, the top of which is provided with a syngas main inlet, a syngas preheating outlet, and a high-pressure saturated steam outlet, and the bottom of which is provided with a methanol syngas outlet; the cylinder is divided into an isothermal section and an adiabatic section from top to bottom; a syngas side inlet is provided between the isothermal section and the adiabatic section; a high-pressure boiler water inlet and a syngas preheating inlet are provided on the cylinder of the isothermal section near the syngas side inlet; the high-pressure boiler water inlet is connected to the high-pressure saturated steam outlet after passing through the isothermal section; and the syngas preheating inlet is connected to the syngas preheating outlet after passing through the isothermal section; The methanol synthesis gas outlet at the bottom of the methanol synthesis reactor passes through the steam superheater and the water cooler in sequence and is communicated with the side inlet of the gas-liquid separation tank.

2. The system according to claim 1, wherein: The isothermal section is provided with a catalyst cylinder I, which is sleeved inside the cylinder and forms a gap I with the inner wall of the cylinder, wherein the gap I forms a gas channel I connected to the main inlet of the synthesis gas; a plurality of external air inlet annular gaps I are provided on the side wall of the catalyst cylinder I; The catalyst cylinder I is sheathed with a central tube I, the upper end of the central tube I is closed, and the lower end is connected to the thermal insulation section; a plurality of inner air intake annular gaps I are provided on the side wall of the central tube I; The reaction zone I is located between the catalyst cylinder I and the central tube I.

3. The system according to claim 1, wherein: The isothermal section is provided with a catalyst cylinder II, which is sleeved inside the cylinder and forms a gap II with the inner wall of the cylinder. The gap II forms a gas channel II communicating with the adiabatic section. A plurality of inner air intake annular gaps II are provided on the side wall of the catalyst cylinder II. The catalyst cylinder II is provided with a central tube II, the upper end of the central tube II is connected to the main inlet of the synthesis gas, and the lower end is closed; a plurality of external air inlet annular gaps II are provided on the side wall of the central tube II; The reaction zone II is located between the catalyst cylinder II and the central tube II.

4. The system according to claim 2, wherein: A plurality of plate heat exchange modules are provided in the reaction zone I, and the plate heat exchange modules are radially arranged with the central tube I as the center; the inlet of the plate heat exchange module is connected to the refrigerant input pipeline, and the outlet of the plate heat exchange module is connected to the refrigerant output pipeline.

5. The system according to claim 3, wherein: A plurality of plate heat exchange modules are provided in the reaction zone II, and the plate heat exchange modules are radially arranged with the central tube II as the center; the inlet of the plate heat exchange module is connected to the refrigerant input pipeline, and the outlet of the plate heat exchange module is connected to the refrigerant output pipeline.

6. The system according to claim 4 or 5, characterized in that The plate heat exchange module includes a high-pressure boiler water channel and a synthesis gas preheating channel; the refrigerant input pipeline includes a high-pressure boiler water riser and a synthesis gas riser; the refrigerant output pipeline includes a high-pressure saturated steam riser and a preheated synthesis gas riser; The high-pressure boiler water riser is connected to the high-pressure saturated steam riser via the high-pressure boiler water channel, and the high-pressure saturated steam riser is connected to the high-pressure saturated steam outlet; the synthesis gas riser is connected to the preheated synthesis gas riser via the synthesis gas preheating channel, and the preheated synthesis gas riser is connected to the synthesis gas preheating outlet; And / or, a plurality of protrusions are provided on the side surface of the plate heat exchange module.

7. The system according to claim 6, characterized in that The inlet of the high-pressure boiler water channel is connected to a plurality of high-pressure boiler water rising pipes, which are converged and connected to a high-pressure boiler water collecting ball, which is connected to the high-pressure boiler water inlet; the outlet of the high-pressure boiler water channel is connected to a plurality of high-pressure saturated steam rising pipes, which are converged to a high-pressure saturated steam collecting ring, which is connected to the high-pressure saturated steam outlet; And / or, the inlet of the synthesis gas preheating channel is connected to multiple synthesis gas risers, the multiple synthesis gas risers are gathered and connected to the synthesis gas collecting annulus, and the synthesis gas collecting annulus is connected to the synthesis gas preheating inlet; the outlet of the synthesis gas preheating channel is connected to multiple preheating synthesis gas risers, the multiple preheating synthesis gas risers are gathered in the preheating synthesis gas collecting ring, and the preheating synthesis gas collecting ring is connected to the synthesis gas preheating outlet.

8. The system according to claim 1, wherein: The synthesis gas side inlet is connected to a gas distributor inside the cylinder; And / or, a gas guide plate is provided inside the cylinder of the insulation section close to the synthesis gas inlet.

9. The system according to claim 1, wherein: The insulation section is provided with an axial reaction catalyst bed; the upper and lower end plates of the axial reaction catalyst bed are connected to the cylinder to form a cavity, and the cavity is used to fill the high-temperature resistant catalyst. The reaction gas passes through the upper end plate, the cavity and the lower end plate in sequence to produce an adiabatic reaction.

10. The system according to claim 2, wherein: The insulation section is provided with a radial reaction catalyst bed; the radial reaction catalyst bed is fixed to the cylinder through a bottom plate, and the bottom plate is connected to the top plate and the left and right side plates to form a cavity, and the cavity is used to fill the high-temperature resistant catalyst. The reaction gas enters the cavity through the left and right side plates to produce an adiabatic reaction.

11. The system according to claim 3, wherein: The insulation section is provided with a radial reaction catalyst bed; the radial reaction catalyst bed is fixed to the cylinder through a bottom plate, and the bottom plate is connected to the top plate and the left and right side plates to form a cavity, and the cavity is used to fill the high-temperature resistant catalyst. The reaction gas enters the cavity through the left and right side plates to produce an adiabatic reaction.

12. The system according to claim 10, wherein: The radial reaction catalyst bed is provided with a central tube III, which is coaxially arranged with the central tube I; a plurality of vents are provided on the side wall of the central tube III; the upper end of the central tube III is closed, and the lower end is connected to the methanol synthesis gas outlet.

13. The system according to claim 11, wherein: The radial reaction catalyst bed is provided with a central tube III, which is coaxially arranged with the central tube II; a plurality of vents are provided on the side wall of the central tube III; the upper end of the central tube III is closed, and the lower end is connected to the methanol synthesis gas outlet.

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