Process method and system for synthesizing methanol through green hydrogen coupled biomass gasification

Abstract

The invention relates to the technical field of methanol synthesis, and particularly discloses a process method and system for synthesizing methanol through green hydrogen coupled biomass gasification, and the process method comprises the steps of biomass pretreatment, gasification, CO conversion, desulfurization and decarburization purification, synthesis of methanol through carbon monoxide hydrogenation, synthesis of methanol through carbon dioxide hydrogenation, methanol rectification, a wind-solar generator set, hydrogen production through water electrolysis and oxygen storage. The two synthesis devices for synthesizing methanol through hydrogenation of carbon monoxide and synthesis of methanol through hydrogenation of carbon dioxide are arranged, so that emission of green carbon can be reduced, and the biomass consumption is reduced; meanwhile, a CO conversion device and two sets of desulfurization and decarbonization purification devices are arranged after gasification, and when the wind and light generating capacity is low and the green hydrogen supply is insufficient, hydrogen can be obtained through conversion and used for subsequent synthesis of a methanol device. The device can reduce the grid power consumption, is high in adjusting capability and high in carbon resource utilization rate, can prevent device shutdown caused by insufficient green hydrogen supply, and ensures the yield of methanol.

Description

Technical Field

[0001] The present invention relates to the technical field of methanol synthesis, and specifically to a process method and system for synthesizing methanol by coupling green hydrogen with biomass gasification. Background Art

[0002] Green electricity refers to electricity produced in a process where CO2 emissions are zero or close to zero. Green electricity is primarily sourced from solar power, wind power, hydropower, biomass energy, geothermal energy, and other sources. The production of green electricity is susceptible to natural conditions. As the scale of green electricity installed continues to grow, timely absorption needs to be considered to avoid "wind and solar power curtailment" or the construction of high-cost chemical energy storage systems. The technical route of using green electricity to electrolyze water to produce hydrogen and then synthesize it into methanol is a good solution. Methanol has a mass energy density of 19.95 GJ / t and can be used as both a high-quality fuel and a bulk basic chemical product. Compared to hydrogen, it has lower storage and transportation costs and is safer. Green methanol is a green hydrogen-based energy source and an important component of the new energy system.

[0003] The traditional coal chemical industry has always been a major source of CO2 emissions. When using coal, natural gas, etc. to prepare chemical raw materials or materials, CO2 emissions are large and the concentration is high. From the perspective of developing green methanol, the green electricity used by green methanol plants produces almost no carbon dioxide. At the same time, through the form of biomass gasification, it can achieve relative "zero emissions" of carbon dioxide. Coupling with green hydrogen (hydrogen) can reduce the CO2 produced by the conversion. However, due to the instability of wind and solar power generation, the green hydrogen produced by renewable energy such as wind and solar power will also fluctuate with wide load. At present, integrated projects such as wind, solar, hydrogen, and ammonia generally ensure chemical hydrogen consumption by disconnecting grid power when wind and solar power generation is insufficient, avoiding the shutdown of chemical plants due to insufficient hydrogen supply. However, this method will result in a high grid power purchase, which is not conducive to the control of carbon emissions of the entire plant, and will cause the plant to shut down under certain extreme operating conditions.

[0004] Therefore, a process method and system for synthesizing methanol by coupling green hydrogen with biomass gasification has become an urgent problem to be solved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a process method and system for synthesizing methanol by coupling green hydrogen with biomass gasification. Through reasonable process steps and device combinations, efficient utilization of biomass, green hydrogen and other resources can be achieved, the efficiency and quality of methanol synthesis can be improved, and production costs and environmental impacts can be reduced.

[0006] To solve the above technical problems, the present invention provides a technical solution: a process for synthesizing methanol by coupling green hydrogen with biomass gasification, comprising the following steps:

[0007] S1. The wind and solar power generators generate electricity to supply the water electrolysis hydrogen production device to produce hydrogen and oxygen. The hydrogen is used as a raw material to supply the carbon monoxide hydrogenation to methanol device and the carbon dioxide hydrogenation to methanol device. The oxygen is supplied to the gasification device directly or through the oxygen storage device.

[0008] S2. The biomass is processed into pellets by a biomass pretreatment device and then enters a gasification device for gasification reaction with the oxygen generated in step S1 to obtain a crude synthesis gas containing CO, CO2, H2 and impurities;

[0009] S3. The crude synthesis gas is divided into two parts. One part is passed through a CO conversion unit to convert CO into CO2, so that the crude synthesis gas becomes a synthesis gas containing CO2, H2 and impurities. The first part is passed through a first desulfurization and decarbonization purification unit to separate H2 and CO2. The H2 is supplied to a carbon monoxide hydrogenation to methanol unit and a carbon dioxide hydrogenation to methanol unit respectively, and the separated CO2 is supplied to a carbon dioxide hydrogenation to methanol unit.

[0010] S4. Another part of the crude synthesis gas is directly passed through the second desulfurization and decarbonization unit to separate H2+CO and CO2. The H2+CO is supplied to the carbon monoxide hydrogenation methanol synthesis unit, and the separated CO2 is supplied to the carbon dioxide hydrogenation methanol synthesis unit;

[0011] S5: The hydrogen produced in step S1 and the CO and hydrogen produced in step S3 enter the carbon monoxide hydrogenation methanol synthesis unit to react to produce crude methanol; the hydrogen produced in step S1 and the CO2 and hydrogen produced in step S4 enter the carbon dioxide hydrogenation methanol synthesis unit to react to produce crude methanol;

[0012] S6. The crude methanol obtained in step S5 is transported to a methanol distillation unit, and the finished methanol is sent out of the boundary.

[0013] Furthermore, the hydrogen obtained in step S1 is mixed with the H2 obtained in step S3 and the H2+CO purified gas obtained in step S4 so that the volume fraction ratio of carbon monoxide and hydrogen in the mixed gas entering the carbon monoxide hydrogenation methanol synthesis device is 1:2.05~2.15, and the purified gas is composed of carbon monoxide and hydrogen.

[0014] Furthermore, the CO2 product gas obtained in step S3 and step S4 is mixed with the H2 obtained in step S1 and step S3 so that the volume fraction ratio of carbon dioxide and hydrogen in the mixed gas entering the carbon dioxide hydrogenation methanol synthesis device is 1:3.05-3.15.

[0015] The present invention also provides a green hydrogen coupled biomass gasification methanol synthesis system, including a wind-solar generator set, a water electrolysis hydrogen production device, an oxygen storage device, a biomass pretreatment device, a gasification device, a CO conversion device, a first desulfurization and decarbonization purification device, a second desulfurization and decarbonization purification device, a carbon monoxide hydrogenation methanol synthesis device, a carbon dioxide hydrogenation methanol synthesis device, and a methanol distillation device;

[0016] The wind-solar generator set is electrically connected to the water electrolysis hydrogen production device, the H2 outlet of the water electrolysis hydrogen production device is connected to the inlet of the carbon monoxide hydrogenation to methanol device and the carbon dioxide hydrogenation to methanol device, the O2 outlet of the water electrolysis hydrogen production device is connected to the oxygen storage device and the inlet of the gasification device, the biomass pretreatment device is connected to the gasification device, the outlet of the gasification device is connected to the CO conversion device and the second desulfurization and decarbonization purification device, the outlet of the CO conversion device is connected to the inlet of the first desulfurization and decarbonization purification device, the H2+CO outlet of the second desulfurization and decarbonization purification device is connected to the inlet of the carbon monoxide hydrogenation to methanol device, the CO2 outlet of the first desulfurization and decarbonization purification device and the CO2 outlet of the second desulfurization and decarbonization purification device are connected to the inlet of the carbon dioxide hydrogenation to methanol device, the H2 outlet of the first desulfurization and decarbonization purification device is connected to the inlet of the carbon monoxide hydrogenation to methanol device and the carbon dioxide hydrogenation to methanol device, and the outlets of the carbon monoxide hydrogenation to methanol device and the carbon dioxide hydrogenation to methanol device are connected to the inlet of the methanol distillation device.

[0017] The advantages of the present invention compared with the prior art are:

[0018] The present invention sets up two synthesis devices, namely a carbon monoxide hydrogenation to methanol device and a carbon dioxide hydrogenation to methanol device. The CO2 generated by the biomass gasification and CO conversion device can be synthesized into methanol through the carbon dioxide hydrogenation to methanol device, thereby reducing CO2 emissions, saving biomass consumption and lowering costs.

[0019] When wind and solar power generation is insufficient, the present invention can generate hydrogen through the CO conversion device to supply hydrogen to the subsequent carbon monoxide and carbon dioxide hydrogenation methanol synthesis device, ensuring the safe and stable operation of the methanol synthesis device, avoiding the shutdown of the device due to interruption of green hydrogen supply, and increasing the overall methanol production.

[0020] The present invention supplies green hydrogen through two routes: water electrolysis and biomass gasification, which can smooth out hydrogen fluctuations and make the methanol synthesis device operate more stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a process flow chart of a process method and system for synthesizing methanol by coupling green hydrogen with biomass gasification according to the present invention.

[0022] As shown in the figure: 1. Wind-solar generator set, 2. Water electrolysis hydrogen production device, 3. Oxygen storage device, 4. Biomass pretreatment device, 5. Gasification device, 6. CO conversion device, 7. First desulfurization and decarbonization purification device, 8. Second desulfurization and decarbonization purification device, 9. Carbon monoxide hydrogenation to methanol device, 10. Carbon dioxide hydrogenation to methanol device, 11. Methanol distillation device. DETAILED DESCRIPTION

[0023] Various exemplary embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention.

[0024] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0025] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0026] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0027] The following is a further detailed description of the process and system for synthesizing methanol by coupling green hydrogen with biomass gasification in conjunction with the accompanying drawings.

[0028] Combined with attachment Figure 1 , the present invention is introduced in detail.

[0029] A process for synthesizing methanol by coupling green hydrogen with biomass gasification comprises the following steps:

[0030] Step S1: Wind-solar generator set 1 generates electricity to supply water electrolysis hydrogen production unit 2 to produce hydrogen (green hydrogen) and oxygen. Hydrogen is used as feedstock to carbon monoxide hydrogenation to methanol unit 9 and carbon dioxide hydrogenation to methanol unit 10. Oxygen is supplied directly or via oxygen storage unit 3 to gasification unit 5. In this step, wind-solar power generation is a renewable energy generation method that converts solar and wind energy into electricity to provide clean electricity for water electrolysis hydrogen production, ensuring that the hydrogen produced is green hydrogen and achieving a low-carbon process.

[0031] Step S2: The biomass is pelletized in biomass pretreatment unit 4 and then enters gasification unit 5 for a gasification reaction with the oxygen generated in step S1, producing crude syngas. The crude syngas contains impurities such as CO, CO₂, H₂, and H₂S. Pre-processing the biomass into pellets increases the contact area between the biomass and oxygen, improving the efficiency and degree of the gasification reaction, and enabling a more complete conversion of the biomass into crude syngas.

[0032] Step S3: The crude syngas is divided into two parts. One part passes through a CO shift converter to convert CO into CO₂, transforming the crude syngas into syngas containing CO₂, H₂, and impurities. The crude syngas then passes through a first desulfurization and decarbonization purification unit 7 to separate the H₂ and CO₂. The H₂ is supplied to a carbon monoxide hydrogenation to methanol unit 9 and a carbon dioxide hydrogenation to methanol unit 10, respectively. The separated CO₂ is supplied to the carbon dioxide hydrogenation to methanol unit 10. Converting CO into CO₂ through the CO shift converter adjusts the composition of the syngas, making it more suitable for the subsequent methanol synthesis reaction and improving the efficiency and yield of methanol synthesis.

[0033] Step S4: Another portion of the crude syngas is directly processed through the second desulfurization and decarbonization unit to separate H₂ + CO from CO₂. The H₂ + CO is supplied to the carbon monoxide hydrogenation to methanol unit 9, and the separated CO₂ is supplied to the carbon dioxide hydrogenation to methanol unit 10. This step directly processes another portion of the crude syngas to quickly separate useful components.

[0034] Step S5: The hydrogen produced in step S1, the CO produced in step S3, and the hydrogen enter the carbon monoxide hydrogenation to methanol unit 9 to react and produce crude methanol. The hydrogen produced in step S1, the CO2 produced in step S4, and the hydrogen enter the carbon dioxide hydrogenation to methanol unit 10 to react and produce crude methanol. By rationally allocating the raw gas (crude synthesis gas), the carbon monoxide hydrogenation to methanol unit 9 and the carbon dioxide hydrogenation to methanol unit 10 can fully utilize the raw materials, thereby improving the production and quality of methanol.

[0035] Step S6: The crude methanol produced in step S5 is transferred to a methanol distillation unit 11 to produce finished methanol. Since the crude methanol contains methanol, water, and some fusel alcohols, the methanol distillation unit 11 is used to purify the crude methanol and remove impurities to produce finished methanol that meets quality standards. The methanol content can be increased to 99.9% by weight through methanol distillation.

[0036] Furthermore, the hydrogen obtained in step S1 is mixed with the H2 obtained in step S3 and the H2+CO purified gas obtained in step S4, so that the volume fraction ratio of carbon monoxide to hydrogen in the mixed gas entering the carbon monoxide hydrogenation to methanol unit 9 is 1:2.05-2.15. The purified gas is composed of carbon monoxide and hydrogen. Precisely controlling the carbon monoxide and hydrogen ratio through automatic valves and flowmeters optimizes the reaction conditions for carbon monoxide hydrogenation to methanol, improves the reaction conversion rate and selectivity, reduces the occurrence of side reactions, and thus increases the yield and quality of methanol.

[0037] Furthermore, the CO2 product gas obtained in steps S3 and S4 is mixed with the H2 obtained in steps S1 and S3 so that the volume fraction ratio of carbon dioxide to hydrogen in the mixed gas entering the carbon dioxide hydrogenation to methanol unit 10 is 1:3.05-3.15. Reasonable control of the carbon dioxide to hydrogen ratio helps improve the efficiency and yield of the carbon dioxide hydrogenation to methanol reaction, allowing the reaction to proceed under optimal conditions and achieving efficient resource utilization.

[0038] To implement the above method, the present invention also provides a green hydrogen coupled biomass gasification to methanol synthesis system, including a wind-solar generator set 1, a water electrolysis hydrogen production device 2, an oxygen storage device 3, a biomass pretreatment device 4, a gasification device 5, a CO conversion device, a first desulfurization and decarbonization purification device 7, a second desulfurization and decarbonization purification device 8, a carbon monoxide hydrogenation to methanol synthesis device 9, a carbon dioxide hydrogenation to methanol synthesis device 10, and a methanol distillation device 11.

[0039] The wind-solar generator set 1 is electrically connected to the water electrolysis hydrogen production device 2 to provide electricity for water electrolysis hydrogen production; the H2 outlet of the water electrolysis hydrogen production device 2 is connected to the inlet of the carbon monoxide hydrogenation methanol synthesis device 9 and the carbon dioxide hydrogenation methanol synthesis device 10, and the produced hydrogen is transported to the methanol synthesis device; the O2 outlet of the water electrolysis hydrogen production device 2 is connected to the oxygen storage device 3 and the inlet of the gasification device 5 to provide oxygen for the gasification device 5; the biomass pretreatment device 4 is connected to the gasification device 5 to transport the pretreated biomass to the gasification device 5; the outlet of the gasification device 5 is connected to the CO conversion device and the second desulfurization and decarbonization purification device 8 to transport the crude synthesis gas to different processing devices respectively; the outlet of the CO conversion device is connected to the inlet of the first desulfurization and decarbonization purification device 7 to transport the converted synthesis gas to the purification device; the second The H2+CO outlet of the desulfurization and decarbonization purification device 8 is connected to the inlet of the carbon monoxide hydrogenation to methanol synthesis device 9, and the purified H2+CO is transported to the carbon monoxide hydrogenation to methanol synthesis device 9; the CO2 outlet of the first desulfurization and decarbonization purification device 7 and the CO2 outlet of the second desulfurization and decarbonization purification device 8 are connected to the inlet of the carbon dioxide hydrogenation to methanol synthesis device 10, and the separated CO2 is transported to the carbon dioxide hydrogenation to methanol synthesis device 10; the H2 outlet of the first desulfurization and decarbonization purification device 7 is connected to the inlet of the carbon monoxide hydrogenation to methanol synthesis device 9 and the carbon dioxide hydrogenation to methanol synthesis device 10, and the purified H2 is transported to the methanol synthesis device; the outlets of the carbon monoxide hydrogenation to methanol synthesis device 9 and the carbon dioxide hydrogenation to methanol synthesis device 10 are connected to the inlet of the methanol distillation device 11, and the crude methanol is transported to the distillation device for purification.

[0040] The specific implementation process of the process and system for synthesizing methanol by coupling green hydrogen with biomass gasification is as follows:

[0041] Example 1

[0042] 3120kg / h biomass pellets and oxygen enter the gasification device 5 to produce 5947Nm 3 / h of crude synthesis gas, the volume fractions of the main gas components of the crude synthesis gas are CO: 26.2%, CO2: 9.24%, H2: 11.36%, H2O: 53.03%, H2S and other: 0.21%. A part of the crude synthesis gas is converted into H2 through the CO conversion device 6 and the first desulfurization and decarbonization purification device 7, with an H2 flow rate of 1110Nm3 / h, and is supplied to the carbon monoxide hydrogenation to methanol synthesis device 9. The removed CO2 is supplied to the carbon dioxide hydrogenation to methanol synthesis device 10. The other part of the crude synthesis gas is not converted by CO and directly enters the second desulfurization and decarbonization purification device 8 to obtain CO+H2 purified gas, and 475Nm3 of green hydrogen is supplemented. 3 / h, and merged with the H2 in the previous part to supply CO+H2 methanol synthesis unit, with a hydrogen-carbon ratio of 2.05. The removed CO2 is supplied to the carbon dioxide hydrogenation methanol synthesis unit 10. The CO2 removed from these two parts and the supplementary green hydrogen 2864Nm 3 / h, and supplies the CO2 hydrogenation to methanol unit 10, with a hydrogen-to-carbon ratio of 3.05. The crude methanol produced by the CO2 hydrogenation to methanol unit 9 is mixed with the crude methanol produced by the CO2 hydrogenation to methanol unit 10 and then enters the methanol distillation unit 11, producing 2580 kg / h of finished methanol.

[0043] Example 2

[0044] 3120kg / h biomass pellets and oxygen enter the gasification device 5 to produce 5947Nm 3 / h of crude synthesis gas, the volume fractions of the main gas components of the crude synthesis gas are CO: 26.2%, CO2: 9.24%, H2: 11.36%, H2O: 53.03%, H2S and other: 0.21%. When the green hydrogen supply is completely interrupted, a part of the crude synthesis gas is converted into H2 through the CO conversion device 6 and the first desulfurization and decarbonization purification device 7. The H2 flow rate for the carbon monoxide hydrogenation to methanol synthesis device 9 is 793Nm3 / h, and the H2 flow rate for the carbon dioxide hydrogenation to methanol synthesis device 10 is 893Nm 3 / h, the removed CO2 is supplied to the carbon dioxide hydrogenation synthesis methanol unit 10, and the other part of the crude synthesis gas is not converted and directly enters the second desulfurization and decarbonization purification unit 8 to obtain CO+H2 purified gas, without adding green hydrogen, and merges with the previous part of H2 to supply carbon monoxide hydrogenation synthesis methanol unit 9, with a hydrogen-carbon ratio of 2.05. The removed CO2 is supplied to the carbon dioxide hydrogenation synthesis methanol unit 10. The CO2 removed from these two parts and the converted hydrogen 893Nm 3 / h, supplied to the CO2 hydrogenation to methanol unit 10, with a hydrogen-to-carbon ratio of 3.05. The crude methanol produced by the CO2 hydrogenation to methanol unit 9 is mixed with the crude methanol produced by the CO2 hydrogenation to methanol unit 10 and then enters the methanol distillation unit 11, producing 1042 kg / h of finished methanol.

[0045] The present invention and its embodiments are described above. This description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs structures and embodiments similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A process for synthesizing methanol by coupling green hydrogen with biomass gasification, characterized in that: The following steps are involved: S1. The wind and solar power generators generate electricity to supply the water electrolysis hydrogen production device to produce hydrogen and oxygen. The hydrogen is used as a raw material to supply the carbon monoxide hydrogenation to methanol device and the carbon dioxide hydrogenation to methanol device. The oxygen is supplied to the gasification device directly or through the oxygen storage device. S2. The biomass is processed into pellets by a biomass pretreatment device and then enters a gasification device for gasification reaction with the oxygen generated in step S1 to obtain a crude synthesis gas containing CO, CO2, H2 and impurities; S3. The crude synthesis gas is divided into two parts. One part is passed through a CO conversion unit to convert CO into CO2, so that the crude synthesis gas becomes a synthesis gas containing CO2, H2 and impurities. The first part is passed through a first desulfurization and decarbonization purification unit to separate H2 and CO2. The H2 is supplied to a carbon monoxide hydrogenation to methanol unit and a carbon dioxide hydrogenation to methanol unit respectively, and the separated CO2 is supplied to a carbon dioxide hydrogenation to methanol unit. S4. Another part of the crude synthesis gas is directly passed through the second desulfurization and decarbonization unit to separate H2+CO and CO2. The H2+CO is supplied to the carbon monoxide hydrogenation methanol synthesis unit, and the separated CO2 is supplied to the carbon dioxide hydrogenation methanol synthesis unit; S5: The hydrogen produced in step S1 and the CO and hydrogen produced in step S3 enter the carbon monoxide hydrogenation methanol synthesis unit to react to produce crude methanol; the hydrogen produced in step S1 and the CO2 and hydrogen produced in step S4 enter the carbon dioxide hydrogenation methanol synthesis unit to react to produce crude methanol; S6. The crude methanol obtained in step S5 is transported to a methanol distillation unit, and the finished methanol is sent out of the boundary.

2. The process for synthesizing methanol by coupling green hydrogen with biomass gasification according to claim 1, characterized in that: The hydrogen obtained in step S1 is mixed with the H2 obtained in step S3 and the H2+CO purified gas obtained in step S4 so that the volume fraction ratio of carbon monoxide to hydrogen in the mixed gas entering the carbon monoxide hydrogenation methanol synthesis device is 1: 2.05~2.15, the purified gas is composed of carbon monoxide and hydrogen.

3. The process for synthesizing methanol by coupling green hydrogen with biomass gasification according to claim 2, characterized in that: The CO2 product gas obtained in steps S3 and S4 is mixed with the H2 obtained in steps S1 and S3 so that the volume fraction ratio of carbon dioxide to hydrogen in the mixed gas entering the carbon dioxide hydrogenation methanol synthesis device is 1:3.05-3.

15.

4. A green hydrogen coupled biomass gasification methanol synthesis system, characterized by: It includes wind and solar power generation units, water electrolysis hydrogen production equipment, oxygen storage equipment, biomass pretreatment equipment, gasification equipment, CO conversion equipment, first desulfurization and decarbonization purification equipment, second desulfurization and decarbonization purification equipment, carbon monoxide hydrogenation to methanol equipment, carbon dioxide hydrogenation to methanol equipment, and methanol distillation equipment; The wind-solar generator set is electrically connected to the water electrolysis hydrogen production device, the H2 outlet of the water electrolysis hydrogen production device is connected to the inlet of the carbon monoxide hydrogenation to methanol device and the carbon dioxide hydrogenation to methanol device, the O2 outlet of the water electrolysis hydrogen production device is connected to the oxygen storage device and the inlet of the gasification device, the biomass pretreatment device is connected to the gasification device, the outlet of the gasification device is connected to the CO conversion device and the second desulfurization and decarbonization purification device, the outlet of the CO conversion device is connected to the inlet of the first desulfurization and decarbonization purification device, the H2+CO outlet of the second desulfurization and decarbonization purification device is connected to the inlet of the carbon monoxide hydrogenation to methanol device, the CO2 outlet of the first desulfurization and decarbonization purification device and the CO2 outlet of the second desulfurization and decarbonization purification device are connected to the inlet of the carbon dioxide hydrogenation to methanol device, the H2 outlet of the first desulfurization and decarbonization purification device is connected to the inlet of the carbon monoxide hydrogenation to methanol device and the carbon dioxide hydrogenation to methanol device, and the outlets of the carbon monoxide hydrogenation to methanol device and the carbon dioxide hydrogenation to methanol device are connected to the inlet of the methanol distillation device.

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