Green methanol synthesis device

Abstract

The utility model provides a green methanol synthesis device, which is used for producing methanol from carbon dioxide and water by using electricity, and comprises a carbon dioxide trapping unit, a water electrolysis hydrogen production unit, a feed gas mixing unit, a water gas inverse transformation reaction unit, a decarburization unit, a carbon dioxide SOEC conversion carbon monoxide unit and a methanol synthesis and purification unit. And the water gas reverse shift reaction unit is arranged at the downstream of the raw material gas mixing unit, is in fluid communication with the raw material gas mixing unit and is used for outputting a reverse shift product containing CO, H2, CO2 and water after the mixed raw material gas is subjected to water gas reverse shift reaction. A carbon dioxide SOEC-to-carbon monoxide unit is disposed downstream of and in fluid communication with the decarburization unit for receiving a CO2-containing gas stream branch and converting CO2 therein into CO and O2. According to the utility model, the SOEC is arranged behind the decarburization unit to further utilize CO2, so that the arrangement of a CO2 circulating compressor with larger volume is avoided, and the whole green methanol synthesis device can be more miniaturized.

Description

Green methanol synthesis unit Technical Field

[0001] This utility model belongs to the field of methanol synthesis technology, specifically relating to a green methanol synthesis device. Background Technology

[0002] Methanol, as an important chemical raw material and energy carrier, has long relied on non-renewable resources such as coal or natural gas for its traditional synthesis processes. Specifically, coal needs to be converted into syngas (CO / H2) through gasification, while natural gas needs to undergo high-temperature reforming to produce syngas. These processes are not only energy-intensive (reaction temperatures typically reach 800-1000℃), but the extraction of raw materials can also cause ecological damage. In addition, traditional processes are accompanied by large amounts of carbon dioxide emissions, exacerbating environmental pressures.

[0003] While green methanol technology has seen some development in recent years, it still has significant drawbacks. For example, although biomass gasification uses renewable resources as raw materials, its gasification products are complex (containing sulfides, tar, etc.), resulting in high purification costs, and carbon dioxide is still produced during the synthesis process. Another type of technology uses carbon dioxide hydrogenation, which requires highly efficient catalysts and high-pressure conditions (such as 10-30 MPa), leading to high equipment investment and operation and maintenance costs. Summary of the Invention

[0004] To address the aforementioned technical problems, this utility model provides a green methanol synthesis device.

[0005] A green methanol synthesis unit that uses electricity to produce methanol from carbon dioxide and water includes: a carbon dioxide capture unit, a water electrolysis hydrogen production unit, a feed gas mixing unit, a water-gas reverse shift reaction unit, a decarbonization unit, a carbon dioxide SOEC to carbon monoxide conversion unit, and a methanol synthesis and purification unit. The carbon dioxide capture unit captures CO2 from industrial waste gas, combustion gas, or CO2-rich process gas. The water electrolysis hydrogen production unit converts water into H2 and O2. The feed gas mixing unit is located downstream of and fluidly connected to the carbon dioxide capture unit and the water electrolysis hydrogen production unit to mix CO2 and H2 to obtain a mixed feed gas. The water-gas reverse shift reaction unit is located downstream of and fluidly connected to the feed gas mixing unit to pass the mixed feed gas through the water-gas reverse shift reaction, outputting a reverse shift product containing CO, H2, CO2, and water. The decarbonization unit is located downstream of and fluidly connected to the water-gas reverse shift reaction unit to remove CO2 from the reverse shift product, outputting a CO2-containing gas stream branch and a CO2-free gas stream branch downstream. The carbon dioxide SOEC to carbon monoxide conversion unit is located downstream of and fluidly connected to the decarbonization unit. It receives a CO2-containing gas stream branch and converts the CO2 in it into CO and O2. The methanol synthesis and purification unit is located downstream of both the decarbonization unit and the carbon dioxide SOEC to carbon monoxide conversion unit and fluidly connected to both. It is used to produce methanol from syngas. The syngas includes CO and H2 from the CO2-free gas stream branch output from the decarbonization unit, as well as CO produced by the carbon dioxide SOEC to carbon monoxide conversion unit.

[0006] Preferably, the system further includes a water treatment unit, which is located upstream of and in fluid communication with the water electrolysis hydrogen production unit. The water treatment unit is used to treat and purify the water and supply the treated water to the water electrolysis hydrogen production unit.

[0007] Furthermore, it also includes a methanol off-gas recovery and circulation pipeline. This pipeline is fluidly connected to the methanol synthesis and purification unit and the feed gas mixing unit, and is used to recover and reuse the feed gas from the methanol off-gas. The feed gas mixing unit is equipped with a purification module that purifies the methanol off-gas to obtain circulating feed gas, which contains H2, CO, and CO2. The feed gas mixture output from the feed gas mixing unit to the water-gas reverse shift reaction unit also includes this circulating feed gas.

[0008] Optionally, the system also includes a syngas compression unit, which is fluidly connected to the decarbonization unit, the carbon dioxide SOEC to carbon monoxide conversion unit, and the methanol synthesis and purification unit. The syngas compression unit compresses and pressurizes the syngas before supplying it to the methanol synthesis and purification unit.

[0009] Furthermore, it also includes a water recycling pipeline 1 and a water recycling pipeline 2. Water recycling pipeline 1 is fluidly connected to the water-gas reverse shift reaction unit and the water treatment unit, and is used for the water recycling and reuse of H2O generated by the water-gas reverse shift reaction unit. Water recycling pipeline 2 is fluidly connected to the syngas compression unit and the water treatment unit, and is used for the water recycling and reuse of H2O separated by the syngas compression unit.

[0010] Specifically, the decarbonization unit is configured as an MDEA wet decarbonization unit or a PSA decarbonization unit.

[0011] Specifically, the water electrolysis hydrogen production unit is configured as an ALK water electrolysis hydrogen production unit or a PEM water electrolysis hydrogen production unit.

[0012] The features and advantages of this disclosure include: the addition of an SOEC after the decarbonization unit for further CO2 utilization avoids the need for a large CO2 recirculation compressor, allowing for a more compact green methanol synthesis unit and facilitating practical applications in smaller facilities. Simultaneously, the elimination of the need for CO2 booster circulation reduces system energy consumption. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 illustrates a green methanol synthesis apparatus according to one embodiment.

[0015] Explanation of reference numerals in the attached figures:

[0016] 11-Water treatment unit, 12-Carbon dioxide capture unit, 13-Water electrolysis hydrogen production unit, 14-Feed gas mixing unit;

[0017] 21-Water-gas reverse shift reaction unit, 22-Decarbonization unit, 23-Synthesis gas compression unit, 24-Methanol synthesis and purification unit;

[0018] 31-Carbon dioxide SOEC conversion carbon monoxide unit;

[0019] 41 - Water recovery circulation pipeline one, 42 - Water recovery circulation pipeline two, 44 ​​- Methanol purge gas recovery circulation pipeline. Detailed Implementation

[0020] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this disclosure.

[0021] This invention provides a green methanol synthesis device that uses carbon dioxide and water as raw materials to produce methanol via electricity, mainly comprising the following chemical reactions:

[0022] Water electrolysis: (1);

[0023] Water-gas reverse conversion: (2);

[0024] SOEC electrolysis of CO2: (3);

[0025] Methanol from syngas: (4).

[0026] Referring to Figure 1, a green methanol synthesis apparatus includes a carbon dioxide capture unit 12, a water electrolysis hydrogen production unit 13, a feed gas mixing unit 14, a water-gas reverse shift reaction unit 21, a decarbonization unit 22, a carbon dioxide SOEC to carbon monoxide conversion unit 31, and a methanol synthesis and purification unit 24. The carbon dioxide capture unit 12 captures CO2 from industrial waste gas, combustion gas, or CO2-rich process gas (such as medium-shift gas from a natural gas to hydrogen system) as one of the feedstocks for synthesizing green methanol. The water electrolysis hydrogen production unit 13 electrolyzes water to produce H2 and oxygen.

[0027] The feed gas mixing unit 14 is located downstream of and in fluid communication with the carbon dioxide capture unit 12 and the water electrolysis hydrogen production unit 13, and is used to mix CO2 and hydrogen to obtain a mixed feed gas. The water-gas reverse shift reaction unit 21 is located downstream of and in fluid communication with the feed gas mixing unit 14, and is used to pass the preheated mixed feed gas through a water-gas reverse shift reaction to output a reverse shift product containing CO, H2, CO2, and water. The H2 in the reverse shift product can be at least one of excess H2 that did not undergo the water-gas reverse shift reaction or H2 produced by the reverse reaction of the water-gas reverse shift reaction.

[0028] The decarbonization unit 22 is located downstream of and in fluid communication with the water-gas reverse shift reaction unit 21. It is used to remove CO2 from the reverse shift products, so as to output a gas flow branch containing CO2 and a gas flow branch without CO2 downstream respectively. The carbon dioxide SOEC to carbon monoxide conversion unit 31 is located downstream of and in fluid communication with the decarbonization unit 22. It is used to receive the gas flow branch containing CO2 and convert the CO2 in the branch into CO and oxygen.

[0029] The methanol synthesis and purification unit 24 is located downstream of the decarbonization unit 22 and the carbon dioxide SOEC to carbon monoxide conversion unit 31 and is in fluid communication with both, and is used to prepare methanol from syngas. The syngas includes CO and hydrogen from the CO2-free gas stream branch output from the decarbonization unit 22, as well as CO generated by the carbon dioxide SOEC to carbon monoxide conversion unit (31).

[0030] The carbon dioxide capture unit 12 is used to capture CO2 from industrial waste gases such as flue gas from coal-fired / gas-fired power plants, kiln tail gas from steel / cement plants, waste gas from oil refining / chemical production, or high-concentration CO2 associated with natural gas processing plants. Capturing CO2 enables emission reduction, storage, and resource utilization, which can address the climate crisis and industrial pollution problems, drive the low-carbon transformation of high-carbon industries, enhance energy security, and promote the development of a circular economy.

[0031] For example, the carbon dioxide capture unit 12 consists of an absorption tower, a regeneration tower, and a solution circulation system. The absorption tower is a vertical packed tower filled with structured packing. A spray device at the top distributes the amine-based absorbent (e.g., amine liquid), and a gas distributor at the bottom guides the CO2-containing industrial waste smoke to countercurrently contact the sprayed amine-based absorbent. The regeneration tower has a built-in reboiler and gas-liquid separation structure, which desorbs the rich liquid through heating. The solution circulation system achieves heat exchange between the rich and lean liquids through a heat exchanger, and maintains the flow of the amine liquid with a circulation pump. During operation, CO2 in the industrial waste smoke chemically combines with the amine liquid in the absorption tower to generate a rich liquid. After being heated by heat exchange, the rich liquid enters the regeneration tower. In the regeneration tower, the rich liquid is heated to release high-purity CO2 gas, forming a regenerated lean liquid. The regenerated lean liquid is cooled and returned to the absorption tower for circulation.

[0032] The water electrolysis hydrogen production unit 13 is used to obtain H2 from raw water. This H2 provides reactants for the water-gas reverse conversion reaction unit 21 and also provides the source of H2 for the synthesis gas required by the methanol synthesis and purification unit 24.

[0033] Optionally, the water electrolysis hydrogen production unit 13 is configured as an ALK alkaline water electrolysis hydrogen production unit. The ALK alkaline water electrolysis hydrogen production unit includes an electrolyzer, electrode assembly, alkaline electrolyte circulation system, and gas separation device. The electrolyzer consists of multiple sets of parallel electrolysis chambers stacked together. Each chamber is divided into a cathode chamber and an anode chamber, respectively fitted with a nickel mesh cathode (with a catalytic layer) and a nickel-based alloy anode. The cathode and anode chambers are separated by a porous membrane, allowing OH⁻ migration but preventing gas cross-contamination. The electrolyte (e.g., a 30% KOH solution) flows continuously between the electrolyzer and an external storage tank via a circulation pump, maintaining electrolyte concentration and temperature. A hydrogen / oxygen liquid separator is installed at the top of the electrolyzer, utilizing gas density differences to separate the products. Hydrogen is collected on the cathode side, and oxygen is discharged on the anode side. A DC power supply provides driving voltage to the electrolyzer through the electrode plates.

[0034] Optionally, the water electrolysis hydrogen production unit 13 is configured as a PEM proton exchange membrane water electrolysis hydrogen production unit. The PEM proton exchange membrane water electrolysis hydrogen production unit includes an electrolyzer, a bipolar plate assembly, membrane electrodes, and a water circulation system. The electrolyzer consists of multiple sets of series-connected electrolysis chambers stacked together. Each chamber is divided into a cathode side and an anode side, where titanium-based gas diffusion electrodes with platinum / iridium catalyst layers can be installed. The cathode and anode are separated by a perfluorosulfonic acid proton exchange membrane (such as a Nafion membrane). Pure water or deionized water is injected into the bipolar plate channels through a circulation pump, uniformly wetting both sides of the membrane electrodes. A titanium alloy gas-liquid separator is integrated at the top of the electrolyzer, utilizing pressure difference and a hydrophobic microporous membrane to achieve hydrogen / oxygen gas separation. High-purity hydrogen is output from the cathode side, and oxygen is discharged from the anode side. A DC power supply applies voltage to the electrolyzer through the noble metal-plated bipolar plates, driving the dissociation of water molecules.

[0035] Preferably, referring to Figure 1, the water required for the water electrolysis hydrogen production unit 13 is provided by the water treatment unit 11. For example, the water treatment unit 11 may include four modules: pretreatment, main treatment, advanced treatment, and post-treatment. The pretreatment module removes large particulate impurities and suspended solids using equipment such as screens, grit chambers, and equalization tanks; the main treatment module includes activated carbon filters and reverse osmosis membranes for adsorbing organic matter, desalinating, and removing microorganisms; the advanced treatment module further improves water quality using technologies such as membrane bioreactors; and the post-treatment module uses ultraviolet light or ozone disinfection to ensure that the water quality meets the requirements of the water electrolysis hydrogen production unit 13.

[0036] In the water-gas reverse shift reaction unit 21, a water-gas reverse shift reaction (RWGS) occurs. This is an equilibrium reaction, and after the reaction, there are both products and reactants. Specifically, the RWGS reaction uses CO2 provided by the carbon dioxide capture unit 12 and H2 provided by the water electrolysis hydrogen production unit 13 as reactants, producing CO and water. The output reverse shift products contain CO, H2, CO2, and water. The H2 in the reverse shift products can be excess H2 from the water-gas reverse shift reaction and / or H2 produced by the reverse reaction of the water-gas reverse shift reaction. Optionally, the reaction pressure is 0.8~3 MPaG, preferably 1.5 MPaG; the reaction temperature is 330~450℃, preferably 380℃.

[0037] The decarbonization unit 22 is used to separate and remove CO2 from the mixed gas containing CO, H2, and CO2 provided by the water-gas reverse shift reaction unit 21, outputting a gas flow branch containing CO2 and a gas flow branch without CO2. The gas flow branch without CO2 contains purified CO and H2, which meets the requirements for synthesis gas in methanol synthesis.

[0038] Optionally, the decarbonization unit 22 is configured as a wet MDEA decarbonization unit, with a basic structure consistent with the carbon dioxide capture unit 12, mainly differing in operating pressure conditions. For example, the reaction pressure of the carbon dioxide capture unit 12 is 50 kPaG, while the reaction pressure of the decarbonization unit 22 is 1.5 MPaG. The wet MDEA decarbonization unit mainly consists of an absorption tower, a regeneration tower, a solution circulation system, and auxiliary equipment. The absorption tower can be a vertical packed tower, filled with bulk or structured packing to increase the gas-liquid contact area. A spray device is installed at the top to evenly distribute the MDEA solution, and a gas distributor is installed at the bottom to guide the CO2-containing gas to rise countercurrently. The regeneration tower often adopts a distillation structure with a reboiler, with built-in trays or packing to promote gas-liquid mass transfer. CO2 is released from the rich liquid by steam heating at the bottom, and a condenser and gas-liquid separator are installed at the top to recover the amine solution and output high-purity CO2 gas. The solution circulation system includes a lean-rich liquid heat exchanger, a circulating pump, and a cooler to achieve heat recovery and temperature regulation of the amine solution. The gaseous components of the CO2-containing reverse conversion products flowing out of the water-gas reverse conversion reaction unit 21 enter from the bottom of the absorption tower and come into countercurrent contact with the lean amine liquid flowing from top to bottom. MDEA (methyl diethanolamine) molecules undergo a reversible reaction with CO2 to generate carbamate, thereby achieving the chemical capture of CO2. The purified gas is discharged from the top of the tower.

[0039] Optionally, the decarbonization unit is configured as a PSA (Pressure Swing Adsorption) decarbonization unit. The PSA decarbonization unit mainly consists of an adsorption tower assembly, a valve switching system, a vacuum desorption system, and a control module. The adsorption tower can be designed as a high-pressure vessel, filled with a composite adsorbent of activated alumina and silica gel. The lower layer of adsorbent is used to remove moisture and impurities, while the upper layer of highly selective adsorbent is dedicated to CO2 capture. A gas distributor is installed at the bottom of the tower to guide the gas components containing CO2 from the reverse shift reaction unit 21 through the adsorption bed uniformly. The valve system can consist of multiple valve sets, which are servo-driven to achieve rapid switching between adsorption, pressure equalization, reverse release, and vacuuming processes. The vacuum desorption system includes a vacuum pump and a buffer tank, used to reduce the pressure inside the tower and desorb and enrich CO2. Under pressurized conditions, the gas components in the CO2-containing reverse shift products enter from the bottom of the adsorption tower, where CO2 molecules are preferentially captured by the adsorbent, and the purified gas is discharged from the top of the tower.

[0040] The carbon dioxide SOEC conversion carbon monoxide unit 31 is used to convert the CO2 separated by the decarbonization unit 22 into CO and O2. The CO obtained from the carbon dioxide SOEC conversion carbon monoxide unit 31, together with the CO and H2 obtained after decarbonization and purification in the decarbonization unit 22, is used as the synthesis gas required by the methanol synthesis purification unit 24.

[0041] The carbon dioxide SOEC to carbon monoxide conversion unit 31 consists of an electrolytic reactor, a gas path system, and a thermal management system. Its basic structure is consistent with the aforementioned SOEC solid oxide water electrolysis hydrogen production unit. The gas path system delivers CO2 to the cathode and removes CO, while carrier gas is introduced at the anode to remove oxygen. The entire unit is driven by external electrical energy to electrochemically decompose CO2, thereby achieving carbon resource conversion.

[0042] Referring to Figure 1, the CO2 separated from the decarbonization unit 22 is converted into CO via the carbon dioxide SOEC conversion carbon monoxide unit 31, and this CO flows to the methanol synthesis purification unit 24. By further converting the CO2 separated from the decarbonization unit 22 into CO, the carbon utilization rate and the synthesis gas content are improved.

[0043] The methanol synthesis and purification unit 24 is used to catalytically synthesize and purify methanol from CO and H2, and includes a synthesis reaction module and a purification module. The synthesis reaction module can be a tubular fixed-bed reactor filled with catalyst. Syngas (CO and H2) enters the reactor and reacts under specific conditions to produce crude methanol (CH3OH) and a small amount of byproducts (such as dimethyl ether, higher alcohols, etc.). The purification module can include a pre-distillation column and a main distillation column. The pre-distillation column removes light components (dissolved CO2, dimethyl ether, etc.) through heating and depressurization, while the main distillation column uses multi-stage trays to separate heavy component impurities (water, higher alcohols). Finally, a condenser is used to obtain refined methanol (green methanol product) with a purity ≥99.85%.

[0044] In some embodiments, the reactor is filled with a copper-based catalyst (e.g., Cu / ZnO / Al2O3), and the syngas with a H2:CO ratio of 2.5~5:1 (volume ratio, preferably 3:1) is pressurized to 3~8 MPaG (preferably 6 MPaG) before entering the reactor. The reaction occurs at 210~270°C (preferably 230°C) to produce crude methanol (CH3OH) and small amounts of byproducts (such as dimethyl ether, higher alcohols, etc.). Accordingly, referring to Figure 1, the green methanol synthesis apparatus also includes a syngas compression unit 23, which compresses the syngas supplied by the decarbonization unit 22 and the carbon dioxide SOEC to carbon monoxide conversion unit 31 to the pressure required for subsequent reactions. Since the CO2-free gas stream output from the decarbonization unit 22 still contains a small amount of water, the syngas compression unit 23 will generate a certain amount of water.

[0045] In other embodiments, the reactor is filled with a highly active catalyst (e.g., Cu-ZnO-ZrO2 or a noble metal system), and the reaction occurs at 250-300°C, with syngas H2:CO≥3 and no pressurization, to produce crude methanol (CH3OH) and a small amount of byproducts (such as dimethyl ether, higher alcohols, etc.).

[0046] During the operation of the methanol synthesis and purification unit 24, purge gas is required, which contains substances such as H2, CO, and CO2. Preferably, referring to Figure 1, the green methanol synthesis device further includes a methanol purge gas recovery and circulation pipeline 44, which extends from the methanol synthesis and purification unit 24 to the feed gas mixing unit 14. The methanol purge gas recovery and circulation pipeline 44 is in fluid communication with both the methanol synthesis and purification unit 24 and the feed gas mixing unit 14, and is used to recover and reuse the feed gas in the methanol purge gas.

[0047] For example, the feed gas mixing unit 14 is equipped with a purification module that purifies the methanol off-gas to obtain a circulating feed gas containing hydrogen, carbon monoxide, and carbon dioxide. The feed gas mixing unit 14 is used to mix H2 provided by the water electrolysis hydrogen production unit 12, CO2 provided by the carbon dioxide capture unit 12, and the circulating feed gas in a certain proportion to obtain a mixed feed gas, which is then transported to the water-gas reverse shift reaction unit 21 as a reaction feedstock. More specifically, a heat exchange module is also provided between the feed gas mixing unit 14 and the water-gas reverse shift reaction unit 21. This heat exchange module is used to preheat the mixed feed gas before it is transported to the water-gas reverse shift reaction unit 21 to participate in the reaction. Optionally, the heating medium in the heat exchange module is provided by crude methanol produced by the methanol synthesis and purification unit 24. After exchanging heat with the mixed feed gas, the crude methanol is guided back to the methanol synthesis and purification unit 24 for purification and cooling to obtain refined methanol.

[0048] Preferably, referring to Figure 1, the green methanol synthesis unit further includes a water recovery circulation pipeline 41 and a water recovery circulation pipeline 42. Water recovery circulation pipeline 41 is in fluid communication with the water-gas reverse shift reaction unit 21 and the water treatment unit 11, and is used for water recycling and reuse of the H2O produced by the water-gas reverse shift reaction unit 21. Water recovery circulation pipeline 42 is in fluid communication with the syngas compression unit 23 and the water treatment unit 11, and is used for water recycling and reuse of the H2O separated by the syngas compression unit 23.

[0049] The above descriptions are merely a few embodiments of this disclosure. Those skilled in the art can make various modifications or variations to the embodiments of this disclosure based on the content disclosed in the application documents without departing from the spirit and scope of this disclosure.

Claims

1. A green methanol synthesis apparatus, wherein the green methanol synthesis apparatus uses electricity to produce methanol from carbon dioxide and water, characterized in that, The green methanol synthesis unit includes: a carbon dioxide capture unit (12) for capturing CO2 from industrial waste gas, combustion gas, or CO2-rich process gas; a water electrolysis hydrogen production unit (13) for converting water into H2 and O2; a feed gas mixing unit (14) located downstream of the carbon dioxide capture unit (12) and the water electrolysis hydrogen production unit (13) and in fluid communication with both, to mix CO2 and H2 to obtain a mixed feed gas; a water-gas reverse shift reaction unit (21) located downstream of the feed gas mixing unit (14) and in fluid communication with it, for outputting a reverse shift product containing CO, H2, CO2, and water after the mixed feed gas undergoes a water-gas reverse shift reaction; and a decarbonization unit (22) located downstream of the water-gas reverse shift reaction unit (21). The unit is in fluid communication with the decarbonization unit (22) and is used to remove CO2 from the reverse conversion products, so as to output a gas flow branch containing CO2 and a gas flow branch without CO2 to the downstream respectively; the carbon dioxide SOEC to carbon monoxide unit (31) is located downstream of the decarbonization unit (22) and is in fluid communication with it, and is used to receive the gas flow branch containing CO2 and convert the CO2 therein into CO and O2; and the methanol synthesis and purification unit (24) is located downstream of the decarbonization unit (22) and the carbon dioxide SOEC to carbon monoxide unit (31) and is in fluid communication with both, and is used to prepare methanol from the synthesis gas; wherein the synthesis gas includes CO and H2 in the gas flow branch without CO2 output by the decarbonization unit (22) and CO generated by the carbon dioxide SOEC to carbon monoxide unit (31).

2. The green methanol synthesis apparatus according to claim 1, characterized in that, It also includes a water treatment unit (11), which is located upstream of the water electrolysis hydrogen production unit (13) and is in fluid communication with it; the water treatment unit (11) is used to treat and purify water and provide the treated water to the water electrolysis hydrogen production unit (13).

3. The green methanol synthesis apparatus according to claim 1, characterized in that, It also includes a methanol off-gas recovery and circulation pipeline (44); the methanol off-gas recovery and circulation pipeline (44) is fluidly connected to the methanol synthesis and purification unit (24) and the raw material gas mixing unit (14) for recovering and utilizing the raw material gas in the methanol off-gas; the raw material gas mixing unit (14) is equipped with a purification module, which purifies the methanol off-gas to obtain circulating raw material gas, which contains H2, CO and CO2; the raw material mixed gas output by the raw material gas mixing unit (14) to the water-gas reverse conversion reaction unit (21) also includes the circulating raw material gas.

4. The green methanol synthesis apparatus according to claim 1, characterized in that, It also includes a syngas compression unit (23), which is in fluid communication with the decarbonization unit (22), the carbon dioxide SOEC to carbon monoxide conversion unit (31), and the methanol synthesis and purification unit (24); the syngas compression unit (23) compresses and pressurizes the syngas before supplying it to the methanol synthesis and purification unit (24).

5. The green methanol synthesis apparatus according to claim 4, characterized in that, It also includes a water recycling pipeline one (41) and a water recycling pipeline two (42); wherein, the water recycling pipeline one (41) is in fluid communication with the water-gas reverse conversion reaction unit (21) and the water treatment unit (11), and is used to recycle and reuse the H2O generated by the water-gas reverse conversion reaction unit (21); the water recycling pipeline two (42) is in fluid communication with the syngas compression unit (23) and the water treatment unit (11), and is used to recycle and reuse the H2O separated by the syngas compression unit (23).

6. The green methanol synthesis apparatus according to claim 1, characterized in that, The decarbonization unit (22) is configured as an MDEA wet decarbonization unit or a PSA decarbonization unit.

7. The green methanol synthesis apparatus according to claim 1, characterized in that, The water electrolysis hydrogen production unit (13) is configured as an ALK water electrolysis hydrogen production unit or a PEM water electrolysis hydrogen production unit.

Images