Multi-process methanol synthesis method and system

Abstract

According to the multi-process methanol synthesis method and system disclosed by the invention, various technological processes such as single-tower one-way, double-tower parallel connection and double-tower series connection are realized through combination of modules and splicing of the modules, different production scenes and requirements can be adapted, and the flexibility and adaptability of the system are improved; when the device runs, assembling and process switching can be carried out, so that the synthesis efficiency is improved, the problem of equipment re-debugging is avoided, the time and the cost are saved, a plurality of processes can be realized only by using the same module due to the adoption of modular design, the production and processing process is greatly simplified, the manufacturing complexity and the manufacturing cost are reduced, and the production efficiency is improved. The modules are arranged in the prying body, so that moving, dismounting and adding are convenient, and the device is particularly suitable for variable new energy projects. By means of the design, the system can be rapidly adjusted and configured according to needs, and the production requirements of different scales are met.

Description

Technical Field

[0001] This invention relates to the field of methanol synthesis, and more particularly to a multi-process methanol synthesis method and system. Background Technology

[0002] Currently, green, low-cost hydrogen obtained from renewable energy sources such as wind and solar power is reacted with carbon monoxide and carbon dioxide to synthesize green methanol. This can effectively address the issue of new energy consumption and also achieve peak shaving. However, due to the significant volatility of green energy sources such as wind power, the green methanol market is still growing and demand is unstable. Existing equipment cannot meet the need to adjust production according to demand.

[0003] In summary, a multi-process methanol synthesis method and system is needed to address the shortcomings of existing technologies. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a multi-process methanol synthesis method and system, aiming to solve the aforementioned problems.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a multi-process methanol synthesis method, comprising the following steps:

[0006] Step S1: Initial state, shut down the compressor and chiller, close all pneumatic valves, and connect carbon dioxide, hydrogen, vent pipes, methanol synthesis gas storage tank and nitrogen;

[0007] Step S2: Purge and replace. Open the nitrogen pneumatic valve to introduce nitrogen for purging. After the set purging time, close all valves. Repeat the set number of times, then pressurize to the set pressure value and depressurize to the set pressure value. Repeat the pressurization and depressurization a set number of times.

[0008] Step S3: The system operates by delivering hydrogen and carbon dioxide to the syngas buffer tank to reach the set pressure. The syngas is heated to the reaction temperature through a heat exchanger and enters the synthesis tower to start the synthesis of methanol. The synthesis products are cooled and separated, and the methanol is delivered to the storage tank. The remaining unreacted gas is returned to the syngas buffer tank through the circulating compressor to participate in the reaction again.

[0009] Step S4: System docking. According to the requirements, the interface between modules is connected by a ferrule through a mechanical transmission device to realize the system in series, parallel or series-parallel connection.

[0010] Step S5: Purge and replace the docking system. Repeat step S2 to purge and replace multiple systems.

[0011] Step S6: Multi-system operation. According to the selected process, open the gas inlet valve of the corresponding module to allow the reaction gas to enter the synthesis gas buffer tank of each module for gas heating, synthesis, cooling, separation, and recycling of the remaining gas.

[0012] Step S7: Shut down the system, close the intake valve, vent the system to a low pressure state, empty the methanol and close all valves, and pressurize and vent the system multiple times with nitrogen.

[0013] Optionally, the purging and displacement in step S2 is performed in the following manner:

[0014] Step A1: Open the nitrogen pneumatic valve to introduce nitrogen, open the system inlet pneumatic valve and venting pneumatic valve to purge the system, and after purging, close all valves to stop the gas intake;

[0015] Step A2: Repeat step A1 until the system is clean;

[0016] Step A3: Open the hydrogen inlet valve to pressurize the system to the set pressure, close the hydrogen inlet valve, maintain the pressure for the set time, and then open the vent valve to depressurize the system.

[0017] Step A4: Repeat step A3 the set number of times.

[0018] Optionally, the system operates in step S3 in the following manner:

[0019] Step B1: Open the inlet pneumatic valve to deliver hydrogen and carbon dioxide to the synthesis gas buffer tank until the set pressure is reached;

[0020] Step B2: Open the synthesis pneumatic valve to introduce the synthesis gas into the first heat exchanger to exchange heat with the synthesis product, then enter the second heat exchanger to be heated to the reaction temperature, and then enter the synthesis tower to start the synthesis.

[0021] Step B3: After the synthesis product is heated by the first heat exchanger, it enters the cooler to be cooled and then enters the separator to separate the synthesis product and transport the methanol to the methanol synthesis storage tank.

[0022] Step B4: The remaining micro-reaction gas is compressed by the circulating compressor and then enters the synthesis gas buffer tank for re-reaction.

[0023] Optionally, step S6 can be performed on multiple systems in the following ways:

[0024] Step C1: Open the corresponding air inlet valves of each module according to the selected process to deliver the reaction gas to the synthesis gas buffer tank to reach the corresponding set pressure;

[0025] Step C2: Open the inlet pneumatic valve of each module to introduce the synthesis gas into the first heat exchanger of the module. After heat exchange with the synthesis product, the gas enters the second heat exchanger of the module and is heated to the reaction temperature before entering the synthesis tower of the module to start the synthesis.

[0026] Step C3: After being cooled by a cooling tower, the synthesis product enters a separator. The separated product is then transported to a methanol synthesis storage tank. The unreacted gas is compressed by a circulating compressor and then enters a synthesis gas buffer tank for re-reaction.

[0027] Optionally, the system may be stopped in step S7 in the following way:

[0028] Step D1: Close the system inlet valve, open the vent valve, vent the system to the set pressure, open the methanol pneumatic valve of each module, and discharge the synthesized methanol to the methanol storage tank;

[0029] Step D2: Open the nitrogen inlet and system inlet valves, pressurize the system to the set pressure, let it stand for a specified time, then open the vent valve to vent to the set high pressure, and repeat the set number of times.

[0030] Optionally, the synthesis method further includes switching between multiple systems and a single system, through the following methods:

[0031] Step E1: Select the module to be shut down, close the module system inlet valve, open the methanol pneumatic valve, and discharge the synthesized methanol into the methanol storage tank;

[0032] Step E2: Open the nitrogen inlet valve and the system inlet valve, pressurize the system to the set pressure, let it stand for a specified time, then open the vent valve to vent to the set high pressure, and repeat the set number of times.

[0033] A multi-process methanol synthesis system, employing the aforementioned multi-process methanol synthesis method, includes several synthesis unit modules. Each synthesis unit module includes a synthesis gas buffer tank, a synthesis tower, a cooler, a first heat exchanger, a second heat exchanger, a circulating compressor, a pneumatic valve, and several interfaces.

[0034] Carbon dioxide is mixed via the first pneumatic valve, and hydrogen is mixed via the second pneumatic valve before being connected to the synthesis gas buffer tank. After passing through the heat exchange pneumatic valve, the hydrogen enters the first heat exchanger to exchange heat with the synthesis products. After being heated to the reaction temperature by the second heat exchanger, the hydrogen enters the synthesis tower to begin synthesizing methanol. The synthesis products, after passing through the first heat exchanger and exchanging heat with the synthesizer, are cooled by the cooler and then enter the separator. After product separation, the methanol is sent to the methanol synthesis storage tank via the methanol pneumatic valve. The remaining unreacted gas is sent to the circulating compressor via the circulating pneumatic valve, compressed, and then enters the synthesis gas buffer tank for re-reaction via the return gas pneumatic valve. The purge gas is sent to the vent via the venting pneumatic valve, and the nitrogen inlet is connected to the synthesis pipeline via an interface.

[0035] The beneficial effects of this invention are:

[0036] 1. In this invention, various processes such as single-tower single-run, double-tower parallel, and double-tower series can be realized through the combination and splicing of modules, which can adapt to various scenarios;

[0037] 2. In this invention, assembly and process switching are performed while the device is running, increasing synthesis efficiency and avoiding the need for equipment readjustment;

[0038] 3. In this invention, a modular design is adopted, which can realize multiple processes with just one module, making production and processing convenient. The module is set in the skid body, which is easy to move, disassemble and install, and is suitable for the changing situation of new energy projects. Attached Figure Description

[0039] Figure 1 This is a flowchart of a synthesis unit module of the present invention.

[0040] Figure 2 This is a flowchart of a series-parallel connection of a synthesis unit module according to the present invention.

[0041] Figure 3 This is a flowchart of a parallel synthesis unit module according to the present invention.

[0042] Figure 4 This is a flowchart of a synthesis unit module series according to the present invention.

[0043] In the diagram: 11. First pneumatic valve; 12. Second pneumatic valve; 13. Nitrogen pneumatic valve; 14. Synthesis gas buffer tank; 15. Heat exchange pneumatic valve; 16. Methanol pneumatic valve; 17. First heat exchanger; 18. Cooler; 19. Separator; 20. Synthesis tower; 21. Circulation pneumatic valve; 22. Venting pneumatic valve; 23. Second heat exchanger; 24. Circulation compressor; 25. Return gas pneumatic valve. Detailed Implementation

[0044] To more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Example 1: As Figure 1 As shown, a multi-process methanol synthesis method, which operates as a single module, includes the following steps:

[0046] I. In the initial state S1:

[0047] The compressor, chiller and other equipment stop running, all pneumatic valves are closed, and the instrument gas supply to each equipment is normal. Carbon dioxide and hydrogen are connected to interface 3 and interface 4, the vent pipe is connected to interface 1, the methanol synthesis storage tank is connected to interface 6, and nitrogen is connected to interface 5.

[0048] II. In the S2 purging and displacement state:

[0049] 1. Open nitrogen pneumatic valve 13 to introduce nitrogen;

[0050] 2. Open the heat exchange pneumatic valve 15, circulation pneumatic valve 21, and venting pneumatic valve 22 of the module, purge the system for 5 minutes, and then close all valves to stop the air intake;

[0051] 3. Repeat steps 1 and 2 three times until no foreign objects fly out of the outlet;

[0052] 4. Open the second pneumatic valve 12 for hydrogen, the heat exchange pneumatic valve 15, and the circulation pneumatic valve 21 to pressurize the system to 1-2 MPa, then close the second pneumatic valve 12 for hydrogen. After stabilizing for 1 minute, open the venting pneumatic valve 22 until the system pressure is 0.2-0.5 MPa, then close it.

[0053] 5. Repeat step 4 5 times.

[0054] III. In S3 single-system operation:

[0055] 1. Open the first pneumatic valve 11 and the second pneumatic valve 12 to deliver hydrogen and carbon dioxide to the synthesis gas buffer tank until the corresponding set pressure is reached;

[0056] 2. Open the heat exchange pneumatic valve 15 to introduce the synthesis gas into the first heat exchanger 17. After exchanging heat with the synthesis product, the gas enters the second heat exchanger 23 and is heated to the reaction temperature before entering the synthesis tower to start the synthesis.

[0057] 3. After the synthesis product passes through the first heat exchanger 17 and exchanges heat with the synthesizer, it is cooled by the cooler and then enters the separator. The methanol pneumatic valve 16 is opened to separate the product and then the methanol is transported to the methanol synthesis storage tank.

[0058] 4. Open the circulating pneumatic valve 21 to compress the remaining unreacted gas through the circulating compressor and then send it into the synthesis gas buffer tank for re-reaction;

[0059] 5. Periodically open the vent valve 22 to release the venting air.

[0060] IV. S7 System Parking Status

[0061] 1. Close the system inlet valve, open the vent valve to vent the system to 0.2-0.5MPa, open the methanol pneumatic valve 16 to discharge the synthesized methanol to the methanol storage tank, and then close all valves.

[0062] 2. Open the nitrogen inlet and system inlet valves, pressurize the system to 2MPa, then close the inlet valves. After waiting for 1 minute, open the vent valve to release the pressure to 0.2-0.5MPa.

[0063] 3. Repeat step 2 5 times.

[0064] 4. Close all valves in the system.

[0065] Example 2, as follows Figure 2 As shown, a multi-process methanol synthesis method, consisting of two modules operating in series and parallel, includes the following steps:

[0066] The compressor, chiller and other equipment stop running, all pneumatic valves are closed, and the instrument gas supply to each equipment is normal. Carbon dioxide and hydrogen are connected to interface 3 and interface 4, the vent pipe is connected to interface 1, the methanol synthesis storage tank is connected to interface 6, nitrogen is connected to interface 5, interface 1 of the second synthesis unit module is connected to interface 7 of the first synthesis unit module, interface 4 of the second synthesis unit module is connected to interfaces 8 and 9 of the first synthesis unit module, and interface 6 of the second synthesis unit module is connected to interface 10 of the first synthesis unit module.

[0067] Step 1, in the initial state S1:

[0068] The compressor, chiller, and other equipment have stopped operating, all pneumatic valves are closed, and the instrumentation gas supply to all equipment is normal. The synthesis gas pipeline is connected to interface 3, the vent pipeline is connected to interface 1, the methanol synthesis storage tank is connected to interface 4, and the nitrogen gas is connected to interface 5.

[0069] Step 2, in the S2 purge and displacement state:

[0070] 1. Open nitrogen pneumatic valve 13 to introduce nitrogen;

[0071] 2. Open the heat exchange pneumatic valve 15, circulation pneumatic valve 21, and venting pneumatic valve 22 of the module, purge the system for 5 minutes, and then close all valves to stop the air intake;

[0072] 3. Repeat steps 1 and 2 three times until no foreign objects fly out of the outlet;

[0073] 4. Open the second pneumatic valve 12 for hydrogen, the heat exchange pneumatic valve 15, and the circulation pneumatic valve 21 to pressurize the system to 1-2 MPa, then close the second pneumatic valve 12 for hydrogen. After stabilizing for 1 minute, open the venting pneumatic valve 22 until the system pressure is 0.2-0.5 MPa, then close it.

[0074] 5. Repeat step 4 5 times.

[0075] Step 3: Single System Running Status:

[0076] 1. Open the first pneumatic valve 11 and the second pneumatic valve 12 to deliver hydrogen and carbon dioxide to the synthesis gas buffer tank until the corresponding set pressure is reached;

[0077] Open the heat exchange pneumatic valve 15 to introduce the synthesis gas into the first heat exchanger 17. After exchanging heat with the synthesis product, the gas enters the second heat exchanger 23 and is heated to the reaction temperature before entering the synthesis tower to start the synthesis.

[0078] 3. After the synthesis product passes through the first heat exchanger 17 and exchanges heat with the synthesizer, it is cooled by the cooler and then enters the separator. The methanol pneumatic valve 16 is opened to separate the product and then the methanol is transported to the methanol synthesis storage tank.

[0079] 4. Open the circulating pneumatic valve 21 to compress the remaining unreacted gas through the circulating compressor and then send it into the synthesis gas buffer tank for re-reaction;

[0080] 5. Periodically open the vent valve 22 to release the venting air.

[0081] Step 4: Multi-system Interoperability Status

[0082] After each interface is extended through the mechanical transmission device, the first synthesis unit module interface 7 is connected to the second synthesis unit module interface 1, the first synthesis unit module interfaces 8 and 9 are connected to the second synthesis unit module interface 4, and the first synthesis unit module interface 10 is connected to the second synthesis unit module interface 6.

[0083] Step 5: Post-dock system purging and replacement status

[0084] 1. Turn on the nitrogen inlet;

[0085] 2) Open the second pneumatic valve 12, the heat exchange pneumatic valve 15, the circulation pneumatic valve 21, and the venting pneumatic valve 22 of the second synthesis unit module, purge the system for 5 minutes, and then close all valves to stop the air intake.

[0086] 3. Repeat steps 1 and 2 three times until no foreign objects fly out of the outlet;

[0087] 4. Open the second intake valve 12 of the second synthesis unit module and the circulating pneumatic valve 21 of the second synthesis unit module to pressurize the system to 1-2MPa, then close the intake pneumatic valve. After stabilizing for 1 minute, open the venting pneumatic valve 22 of the second synthesis unit module until the system pressure is 0.2-0.5MPa, then close it.

[0088] 5) Repeat step 4 5 times.

[0089] Step Six: Check the operating status of multiple systems

[0090] 1) Open the first pneumatic valve 11, the second pneumatic valve 12, the heat exchange pneumatic valve 15 of the first synthesis unit module, the second pneumatic valve 12 of the second synthesis unit module, and the heat exchange pneumatic valve 15 of the second synthesis unit module to combine the synthesis gas and the remaining unreacted gas of the first synthesis unit module and deliver them to the synthesis gas buffer tank until the corresponding set pressure is reached.

[0091] 2) Open the heat exchange pneumatic valve 15 of the second synthesis unit module to introduce the synthesis gas into the first heat exchanger 17 of the second synthesis unit module. After exchanging heat with the synthesis product, the gas enters the second heat exchanger 23 of the second synthesis unit module and is heated to the reaction temperature before entering the synthesis tower of the second synthesis unit module to start the synthesis.

[0092] 3) After the synthesis product passes through the first heat exchanger 17 of the second synthesis unit module and exchanges heat with the synthesizer of the second synthesis unit module, it is cooled by the cooler of the second synthesis unit module and then enters the separator of the second synthesis unit module. The methanol pneumatic valve 16 of the second synthesis unit module is opened to separate the product and transport the methanol to the methanol synthesis storage tank.

[0093] 4) Open the circulating pneumatic valve 21 of the second synthesis unit module to compress the remaining unreacted gas through the circulating compressor and then enter the synthesis gas buffer tank for re-reaction;

[0094] 5) Periodically open the heat exchange pneumatic valve 15 of the second synthesis unit module to release the vent gas.

[0095] Step 7: System Stop Status

[0096] 1. Close the system inlet valve, open the vent valve to vent the system to 0.2-0.5MPa, open the methanol pneumatic valve 16 of the first synthesis unit module and the second synthesis unit module to discharge the synthesized methanol to the methanol storage tank, and then close all valves;

[0097] 2. Open the nitrogen inlet and system inlet valves, pressurize the system to 2MPa, then close the inlet valves. After waiting for 1 minute, open the vent valves to release the gas to 0.2-0.5MPa.

[0098] 3. Repeat step 2 5 times;

[0099] 4. Close all valves in the system.

[0100] Example 3, as follows Figure 3 As shown, the two modules operate in parallel. The difference from Embodiment 2 is that the connection method between the first synthesis unit module and the second synthesis unit module is different: the interface 7 of the first synthesis unit module is connected to the interface 1 of the second synthesis unit module, the interface 9 of the first synthesis unit module is connected to the interface 4 of the second synthesis unit module, and the interface 10 of the first synthesis unit module is connected to the interface 6 of the second synthesis unit module.

[0101] Example 4, as Figure 4 As shown, the two modules operate in series. The difference from Embodiment 2 is that the connection method between the first synthesis unit module and the second synthesis unit module is different: the interface 7 of the first synthesis unit module is connected to the interface 1 of the second synthesis unit module, the interface 8 of the first synthesis unit module is connected to the interface 4 of the second synthesis unit module, and the interface 10 of the first synthesis unit module is connected to the interface 6 of the second synthesis unit module.

[0102] Examples two, three, and four also involve switching from a multi-system module to a single-system module, through the following methods:

[0103] 1. Close the first and second pneumatic valves of the second synthesis unit module 2 system;

[0104] 2. Open the venting valve of the second synthesis unit module to vent the system to 0.2-0.5MPa, open the methanol venting valve of the second synthesis unit module to discharge the synthesized methanol into the methanol storage tank, and then close all valves.

[0105] 3. Open the nitrogen pneumatic valve and the second pneumatic valve of the second synthesis unit module, pressurize the system to 2MPa, then close the second pneumatic valve. After waiting for 1 minute, open the vent valve to release the pressure to 0.2-0.5MPa.

[0106] 4. Repeat step 2 5 times.

[0107] 5. Close all valves in the system.

[0108] 6. Disconnect all interface connections.

[0109] This invention achieves various process flows such as single-tower single-pass, double-tower parallel, and double-tower series by combining and splicing modules, which can adapt to different production scenarios and needs, increasing the system's flexibility and adaptability. Assembly and process switching can be performed during device operation, which not only improves synthesis efficiency but also avoids the problem of equipment re-debugging, saving time and costs.

[0110] The modular design allows for multiple processes to be implemented using a single module, greatly simplifying the production process and reducing manufacturing complexity and costs. The modules are housed within the skid, facilitating easy movement, disassembly, and installation, making them particularly suitable for the dynamic nature of new energy projects. This design enables the system to be quickly configured as needed to meet the production demands of different scales.

[0111] The system design takes into account the fluctuating characteristics of green energy such as wind power, and provides a variety of process options, from single-pass synthesis to complex dual-tower series-parallel synthesis, to ensure effective operation under both poor and good conditions of new energy consumption. Through an effective gas recycling mechanism, such as returning unreacted gas to the buffer tank via a recirculating compressor, the system maximizes the use of raw material gas, reduces waste, and improves resource utilization. It also utilizes hydrogen generated from renewable energy to synthesize green methanol with carbon monoxide or carbon dioxide, which helps reduce greenhouse gas emissions.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-process methanol synthesis method, characterized in that, Includes the following steps: Step S1: Initial state, shut down the compressor and chiller, close all pneumatic valves, and connect carbon dioxide, hydrogen, vent pipes, methanol synthesis gas storage tank and nitrogen; Step S2: Purge and replace. Open the nitrogen pneumatic valve to introduce nitrogen for purging. After the set purging time, close all valves. Repeat the set number of times, then pressurize to the set pressure value and depressurize to the set pressure value. Repeat the pressurization and depressurization a set number of times. Step S3: The system operates by delivering hydrogen and carbon dioxide to the syngas buffer tank to reach the set pressure. The syngas is heated to the reaction temperature through a heat exchanger and enters the synthesis tower to start the synthesis of methanol. The synthesis products are cooled and separated, and the methanol is delivered to the storage tank. The remaining unreacted gas is returned to the syngas buffer tank through the circulating compressor to participate in the reaction again. Step S4: System docking. According to the requirements, the interface between modules is connected by a ferrule through a mechanical transmission device to realize the system in series, parallel or series-parallel connection. Step S5: Purge and replace the docking system. Repeat step S2 to purge and replace multiple systems. Step S6: Multi-system operation. According to the selected process, open the gas inlet valve of the corresponding module to allow the reaction gas to enter the synthesis gas buffer tank of each module for gas heating, synthesis, cooling, separation, and recycling of the remaining gas. Step S7: Shut down the system, close the intake valve, vent the system to a low pressure state, empty the methanol and close all valves, and pressurize and vent the system multiple times with nitrogen.

2. The multi-process methanol synthesis method according to claim 1, characterized in that, The purging and displacement in step S2 is performed in the following manner: Step A1: Open the nitrogen pneumatic valve to introduce nitrogen, open the system inlet pneumatic valve and vent pneumatic valve to purge the system, and after purging, close all valves to stop the gas intake; Step A2: Repeat step A1 until the system is clean; Step A3: Open the hydrogen inlet valve to pressurize the system to the set pressure, close the hydrogen inlet valve, maintain the pressure for the set time, and then open the vent valve to depressurize the system. Step A4: Repeat step A3 the set number of times.

3. The multi-process methanol synthesis method according to claim 1, characterized in that, The system operates in step S3 in the following manner: Step B1: Open the inlet pneumatic valve to deliver hydrogen and carbon dioxide to the synthesis gas buffer tank until the set pressure is reached; Step B2: Open the synthesis pneumatic valve to introduce the synthesis gas into the first heat exchanger to exchange heat with the synthesis product, then enter the second heat exchanger to be heated to the reaction temperature, and then enter the synthesis tower to start the synthesis. Step B3: After the synthesis product is heated by the first heat exchanger, it enters the cooler to be cooled and then enters the separator to separate the synthesis product and transport the methanol to the methanol synthesis storage tank. Step B4: The remaining micro-reaction gas is compressed by the circulating compressor and then enters the synthesis gas buffer tank for re-reaction.

4. The multi-process methanol synthesis method according to claim 1, characterized in that, The multi-system operation in step S6 is achieved through the following methods: Step C1: Open the corresponding air inlet valves of each module according to the selected process to deliver the reaction gas to the synthesis gas buffer tank to reach the corresponding set pressure; Step C2: Open the inlet pneumatic valve of each module to introduce the synthesis gas into the first heat exchanger of the module. After heat exchange with the synthesis product, the gas enters the second heat exchanger of the module and is heated to the reaction temperature before entering the synthesis tower of the module to start the synthesis. Step C3: After being cooled by a cooling tower, the synthesis product enters a separator. The separated product is then transported to a methanol synthesis storage tank. The unreacted gas is compressed by a circulating compressor and then enters a synthesis gas buffer tank for re-reaction.

5. The multi-process methanol synthesis method according to claim 1, characterized in that, In step S7, the system stops in the following way: Step D1: Close the system inlet valve, open the vent valve, vent the system to the set pressure, open the methanol pneumatic valve of each module, and discharge the synthesized methanol to the methanol storage tank; Step D2: Open the nitrogen inlet and system inlet valves, pressurize the system to the set pressure, let it stand for a specified time, then open the vent valve to release the gas to the set high pressure, and repeat the set number of times.

6. The multi-process methanol synthesis method according to claim 1, characterized in that, The synthesis method also includes switching between multiple systems and a single system, through the following methods: Step E1: Select the module to be shut down, close the module system inlet valve, open the methanol pneumatic valve, and discharge the synthesized methanol into the methanol storage tank; Step E2: Open the nitrogen inlet valve and the system inlet valve, pressurize the system to the set pressure, let it stand for a specified time, then open the vent valve to release the gas to the set high pressure, and repeat the set number of times.

7. A multi-process methanol synthesis system, employing the multi-process methanol synthesis method as described in any one of claims 1-6, characterized in that, It includes several synthesis unit modules, which include a synthesis gas buffer tank, a synthesis tower, a cooler, a first heat exchanger, a second heat exchanger, a circulating compressor, a pneumatic valve, and several interfaces; Carbon dioxide is mixed via the first pneumatic valve, and hydrogen is mixed via the second pneumatic valve before being connected to the synthesis gas buffer tank. After passing through the heat exchange pneumatic valve, the hydrogen enters the first heat exchanger to exchange heat with the synthesis products. After being heated to the reaction temperature by the second heat exchanger, the hydrogen enters the synthesis tower to begin synthesizing methanol. The synthesis products, after passing through the first heat exchanger and exchanging heat with the synthesizer, are cooled by the cooler and then enter the separator. After product separation, the methanol is sent to the methanol synthesis storage tank via the methanol pneumatic valve. The remaining unreacted gas is sent to the circulating compressor via the circulating pneumatic valve, compressed, and then enters the synthesis gas buffer tank for re-reaction via the return gas pneumatic valve. The purge gas is sent to the vent via the venting pneumatic valve, and the nitrogen inlet is connected to the synthesis pipeline via an interface.

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