Low-carbon production system and method for hydrogen-assisted production of metal oxides and methanol from carbonates

Abstract

This invention relates to a low-carbon production system and method for hydrogen-assisted production of metal oxides and methanol from carbonates. The system uses carbonates as raw materials, converting them into metal oxides via a hydrogenation reaction, and releasing the carbon from the carbonates as carbon dioxide (CO2) into high-value-added methanol. Due to the inertness of carbonates and the thermodynamic limitations of carbonate hydrogenation, an excess of hydrogen is required to achieve the ideal carbonate conversion rate. Therefore, the system utilizes a high hydrogen / carbon (H / C) ratio during the carbonate conversion process to first generate hydrogen-rich syngas, which is then efficiently converted into methanol. Further gas-liquid separation is used to purify the methanol and hydrogen-rich gas. The reuse of the hydrogen-rich gas improves the utilization efficiency of hydrogen in the process of producing metal oxides and methanol from carbonates.

Description

Technical Field

[0001] This invention belongs to the field of carbon emission reduction technology and is used for energy conservation, emission reduction and efficiency improvement in energy-intensive industries. Specifically, it relates to a low-carbon production system and method for producing metal oxides and methanol from hydrogen-assisted carbonates. Background Technology

[0002] Energy-intensive industries such as steel, refractory materials, and cement, which rely on carbonate calcination as their basic production process, generate enormous carbon emissions, accounting for 50% of my country's total industrial carbon emissions. The high carbon emissions from these processes are primarily due to the inevitable high-temperature decomposition of carbonate raw materials, which produces large amounts of carbon dioxide (CO2). Simultaneously, the combustion of fossil fuels necessary for high-temperature manufacturing processes also generates significant amounts of CO2. To address the bottleneck in carbon emission reduction in these industries, various carbon neutrality technologies, including carbon capture, utilization, and storage (CCUS), have been proposed. Among these, capturing CO2 generated during the production process using amine solvent absorption, followed by hydrogenation reduction of the released CO2 to prepare various carbon-based chemicals, is currently a widely accepted carbon neutrality baseline technology. However, the CCUS process involves complex steps such as carbon capture, purification, compression, transportation, and hydrogenation conversion, resulting in a long process flow, high energy consumption, and high costs, preventing its large-scale promotion and application to date.

[0003] Unlike CCUS technology, carbonate hydrogenation refining technology has attracted great attention as a disruptive low-carbon technology. It aims to change the traditional way in which carbonates are calcined and decomposed in air to produce CO2. By hydrogenating, the carbon resources in carbonates are utilized into carbon-based high-value-added products, while at the same time reducing the temperature required for carbonate decomposition to synergistically form a low-carbon technology.

[0004] Currently, the products of carbonate hydrogenation refining technology are limited to low-value-added products such as CO or CH4, and these products are all in the gaseous phase. They are difficult to separate and purify when mixed with large amounts of excess hydrogen-containing reducing gases, leading to additional energy consumption and operating costs, as well as difficulties in recycling the hydrogen-containing reducing gases. Since hydrogen is still primarily derived from petroleum fuels (>95%), its production process involves huge energy consumption and CO2 emissions; and the proportion of new technologies utilizing renewable energy for hydrogen production is low (<5%), indicating a long road ahead in reducing costs and increasing production capacity.

[0005] Converting the gaseous products from carbonate hydrogenation into liquid high-value-added products (such as methanol) allows for the separation and purification of the products and excess hydrogen through simple gas-liquid separation, while also enabling efficient hydrogen reuse. This invention proposes a low-carbon production system and method for the efficient hydrogen-assisted production of metal oxides and methanol from carbonate. The system co-produces metal oxides and methanol through carbonate hydrogenation, with the solid phase product being metal oxides. The gaseous product, after cooling, is separated into hydrogen-rich gas and liquid crude methanol through a gas-liquid separation system. The hydrogen-rich gas is reused for efficient hydrogen resource utilization, while the liquid crude methanol is purified by distillation to obtain liquid refined methanol. More importantly, by controlling and utilizing the high H / C ratio of the reaction gas, the efficient production of metal oxides and methanol from carbonate decomposition is ensured. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the first objective of this invention is to provide a low-carbon production system for producing metal oxides and methanol using hydrogen-assisted carbonates, and the second objective is to provide a corresponding production method that can improve hydrogen utilization efficiency and co-produce metal oxides and high-value-added methanol products.

[0007] The technical principle of this invention is as follows: The low-carbon production system of this invention uses carbonates as raw materials, converting carbonates into metal oxides through a hydrogenation reaction, and releasing the carbon in the carbonates from the form of carbon dioxide (CO2) into methanol, which has high added value. Due to the inertness of carbonates and the thermodynamic limitations of carbonate hydrogenation reactions, excess hydrogen is required to achieve the ideal carbonate conversion rate. Therefore, by utilizing the high hydrogen / carbon (H / C) ratio in the carbonate conversion process, hydrogen-rich syngas is first generated, and then efficiently converted into high-value-added methanol chemicals. Furthermore, methanol and hydrogen-rich gas are purified through gas-liquid separation. By reusing the hydrogen-rich gas, the utilization efficiency of hydrogen in the process of carbonate hydrogenation to produce metal oxides and methanol is improved.

[0008] Based on the above principles, the specific technical solution of the present invention is as follows:

[0009] In a first aspect, the present invention provides a low-carbon production system for producing metal oxides and methanol from carbonates with hydrogen assistance, comprising: a carbonate hydrogenation reactor (1) having a carbonate inlet and a hydrogen inlet thereon, wherein carbonates are completely reacted with preheated mixed hydrogen-rich gas to generate metal oxides and syngas with a high H2 / CO ratio, the outlet of which is connected to a metal oxide and syngas separator (2), the syngas outlet of which is connected to a syngas post-processing system, and the metal oxide outlet is connected to a first cooler (3) for cooling the generated metal oxides;

[0010] The syngas post-processing system includes a first heat exchanger (4), a second cooler (5), a third cooler (6), a first gas-liquid separator (7), a turbine compressor (8), and a second heat exchanger (9) connected in sequence. The inlet of the first heat exchanger (4) is connected to both the syngas outlet and the hydrogen-rich gas mixer (16), and the outlet is connected to the carbonate hydrogenation reactor (1) and the second cooler (5), respectively. After the syngas is fully preheated and mixed with the hydrogen-rich gas by the first heat exchanger (4), it continues to pass through the second cooler (5) and the third cooler (6) to recover residual heat and further cool. The cooled syngas is dehydrated by the first gas-liquid separator (7) and pressurized to the required pressure by the turbine compressor (8) before being input into the second heat exchanger (9). After being fully preheated by the product gas at the outlet of the methanol reactor (10), it is used for methanol synthesis.

[0011] The methanol reaction system includes a methanol reactor (10), a pressure reducing valve (11), a fourth cooler (12), a fifth cooler (13), a second gas-liquid separator (14), and a distillation column (15) connected in sequence. The methanol reactor (10) is equipped with heat exchange tubes to recover heat and avoid hot spot effects. At the second heat exchanger (9), the outlet product gas, after heat exchange, is reduced to the required pressure by the pressure reducing valve (11), and then sequentially passes through the fourth cooler (12) and the fifth cooler (13). The process involves heat recovery and further cooling, with the recovered heat used for the reboiler of the distillation column (15); the top outlet of the second gas-liquid separator (14) is connected to the hydrogen-rich gas mixer (16), which separates the cooled outlet product gas into crude methanol and hydrogen-rich gas. This hydrogen-rich gas is mixed with a small amount of supplemental hydrogen in the hydrogen-rich gas mixer (16) to obtain a mixed hydrogen-rich gas, which is then reused in the carbonate hydrogenation reactor (1); the distillation column (15) further separates and purifies the crude methanol into refined methanol.

[0012] Preferably, the carbonate hydrogenation reactor (1) is selected from one or a combination of two of fluidized bed, moving bed, and fixed bed reactors. Specifically, fluidized bed reactors include bubbling fluidized beds, turbulent fluidized beds, dense phase conveying beds, and dilute phase conveying beds; fixed bed reactors include axial fixed bed reactors, radial fixed bed reactors, and tubular fixed bed reactors.

[0013] Furthermore, to improve hydrogen utilization efficiency and ensure efficient subsequent methanol production, the carbonate hydrogenation reactor is configured based on the volume ratio of H2 / CO in the syngas. If the H2 / CO volume ratio is 8–12, a multi-tower parallel configuration with a single tower unit is used. If a single tower unit cannot meet the target H2 / CO volume ratio in the syngas at the outlet, a multi-tower parallel configuration with a dual-tower series unit is used. That is, the low-CO-concentration hydrogen-rich gas output from the front tower is used for carbonate hydrogenation conversion in the rear tower to further improve the CO concentration and hydrogen utilization efficiency in the final output syngas.

[0014] When the carbonate hydrogenation reactor adopts a dual-tower series unit, it includes a first dual-way control valve (17), a three-way control valve (18), and a second dual-way control valve (19) connected in series, as well as a first carbonate hydrogenation reactor (20) and a second carbonate hydrogenation reactor (21) connected in series.

[0015] The three-way control valve (18) is connected to the hydrogen inlet of both the first carbonate hydrogenation reactor (20) and the second carbonate hydrogenation reactor (21). The first two-way control valve (17) and the second two-way control valve (19) are connected to the synthesis gas outlet of both the first carbonate hydrogenation reactor (20) and the second carbonate hydrogenation reactor (21), respectively.

[0016] Preferably, the metal oxide and syngas separator (2) is a cyclone separator connected to the outlet of the carbonate hydrogenation reactor (1), which is used to separate the metal oxide and syngas. The separated metal oxide is discharged from the system after its heat is fully recovered by the first cooler (3). The separated syngas passes through the first heat exchanger (4), the second cooler (5), and the third cooler (6) in sequence to fully preheat the mixed hydrogen-rich gas for recycling, further recover heat, and further cool. The recovered heat is used to produce low-pressure steam, medium-pressure steam, or high-pressure steam for power generation, heating, or sale. The cooled syngas continues to pass through the first gas-liquid separator (7) to remove moisture and is then fed into the turbine compressor (8). The turbine compressor is used to pressurize the syngas to the required pressure. The pressurized syngas is fully preheated by the second heat exchanger and then fed into the methanol reactor (10).

[0017] Preferably, the methanol reactor (10) is used to further convert the syngas into methanol; the high H2 / CO ratio (8-12) of the syngas allows CO to be almost completely converted into methanol, outputting an outlet product gas containing methanol, water, hydrogen, and small amounts of carbon monoxide and carbon dioxide, but at the same time, the high-intensity syngas-to-methanol reaction also generates a large amount of reaction heat; in order to maintain the ideal reaction temperature and avoid hot spot effects, heat exchange tubes embedded in the reaction bed are deployed in the methanol reactor to remove the released heat in a timely manner and produce low-pressure steam, medium-pressure steam, or high-pressure steam for power generation, heating, or sale; the outlet product gas passes sequentially through the second heat exchanger, pressure reducing valve, fourth cooler, and fifth cooler to complete the preheating, depressurization to the required pressure, further heat recovery, and further cooling of the syngas; the recovered heat is used for the reboiler of the distillation column;

[0018] Optionally, the heat exchanger and cooler include shell-and-tube heat exchangers, finned heat exchangers, plate heat exchangers, and coil heat exchangers.

[0019] Based on the physical properties of water and methanol being easily liquefied, the second gas-liquid separator can separate water and methanol in the cooled outlet product gas in the form of liquid crude methanol from hydrogen and a hydrogen-rich gas composed of a small amount of carbon monoxide and carbon dioxide in a low-energy and low-cost manner.

[0020] Based on the above scheme, crude methanol is separated from water by the distillation column to obtain refined methanol with a high methanol concentration; optionally, the distillation column is a plate column or a packed column.

[0021] Based on the above scheme, hydrogen-rich gas is mixed with a small amount of fresh hydrogen in the mixer to form the mixed hydrogen-rich gas, which is then reused in the carbonate hydrogenation conversion process, thereby significantly improving hydrogen utilization efficiency.

[0022] In a second aspect, the present invention provides a method for producing metal oxides and methanol from hydrogen-assisted carbonates using the above-described production system, summarized as follows:

[0023] (1) Using carbonate as raw material, hydrogenate it to convert it into metal oxide while outputting syngas with a high H2 / CO ratio (8-12);

[0024] (2) The syngas is further converted into methanol products with higher added value; due to the high H2 / CO ratio (8-12) of the syngas, CO is almost completely converted into methanol, and the final output product gas contains hydrogen, methanol, water, a small amount of carbon monoxide and carbon dioxide.

[0025] (3) Based on the physical properties of easy liquefaction of water and methanol, the liquid crude methanol composed of water and methanol can be separated from hydrogen and a small amount of hydrogen-rich gas composed of carbon monoxide and carbon dioxide through low-energy consumption and low-cost gas-liquid separation; the crude methanol is distilled to obtain water and refined methanol respectively; the hydrogen-rich gas is mixed with a certain amount of fresh hydrogen to form a mixed hydrogen-rich gas, which is then reused in the carbonate hydrogenation conversion process, thereby greatly improving the hydrogen utilization efficiency.

[0026] The specific production steps are as follows:

[0027] Carbonate and preheated mixed hydrogen-rich gas are added to the carbonate hydrogenation reactor (1) through the carbonate inlet and the hydrogen inlet, respectively, and react completely to generate metal oxide and syngas with a high H2 / CO ratio. After being separated by the metal oxide and syngas separator (2), the metal oxide is discharged from the system after recovering heat through the first cooler (3).

[0028] After the synthesis gas is fully preheated and mixed with hydrogen-rich gas by the first heat exchanger (4), it continues to pass through the second cooler (5) and the third cooling zone (6) to recover waste heat and further cool. The cooled synthesis gas is then dehydrated by the first gas-liquid separator (7) and pressurized to the required pressure by the turbine compressor (8) before being input into the second heat exchanger (9). After being fully preheated by the outlet product gas of the methanol reactor (10), it is used for methanol synthesis.

[0029] The outlet product gas generated in the methanol reactor (10) is reduced to the required pressure by the pressure reducing valve (11) after heat exchange, and then passes through the fourth cooler (12) and the fifth cooler (13) in sequence to recover heat and further cool. The recovered heat is used for the reboiler of the distillation column (15). The cooled outlet product gas is separated into crude methanol and hydrogen-rich gas by the second gas-liquid separator (14). The hydrogen-rich gas is mixed with a small amount of supplementary hydrogen in the hydrogen-rich gas mixer (16) to obtain mixed hydrogen-rich gas, which is then reused in the carbonate hydrogenation reactor (1). The crude methanol is further separated and purified into refined methanol by the distillation column (15).

[0030] Preferably, when a single-tower unit cannot meet the target H2 / CO volume ratio (8-12) in the syngas at the outlet, a dual-tower series unit is used; the operation steps are as follows:

[0031] First, close the external passage of the first double-port control valve (17). The mixed hydrogen-rich gas enters the first carbonate hydrogenation reactor (20) through the three-port control valve (18) for hydrogenation reaction. The low CO concentration hydrogen-rich gas output from the first carbonate hydrogenation reactor (20) is used for hydrogenation reaction in the second carbonate hydrogenation reactor (21). The high CO concentration synthesis gas is output externally through the second double-port control valve (19).

[0032] Due to the decrease in hydrogen concentration in the reaction gas and the lag in pipeline transportation, the first carbonate hydrogenation reactor (20) will complete the carbonate hydrogenation conversion before the second carbonate hydrogenation reactor (21). At this time, the three-way control valve (18) switches the gas path direction to transport the mixed hydrogen-rich gas to the second carbonate hydrogenation reactor (21), the second double-way control valve (19) closes the external passage, and the first double-way control valve (17) opens the external passage. After the fresh carbonate in the first carbonate hydrogenation reactor (20) is fed, the above hydrogenation conversion process is repeated.

[0033] Preferably, the carbonate is selected from calcium carbonate, magnesium carbonate, ferrous carbonate, or natural minerals with these as the main components, including one or more combinations of dolomite, calcite, limestone, magnesite, siderite, and ferrodolomite; the carbonate is fed into the carbonate hydrogenation reactor in a one-time, batch, or continuous manner.

[0034] Hydrogen is produced from fossil fuels, nuclear power water electrolysis, nuclear high-temperature reactor thermochemical hydrogen production, renewable energy power generation water electrolysis, photocatalytic water splitting, biological reforming, or algal photosynthesis.

[0035] Further optimization yields the following reaction conditions for the carbonate hydrogenation reactor: pressure from atmospheric pressure to 1 MPa, and temperature from 350°C to 1200°C.

[0036] When the carbonate hydrogenation reactor is a single-tower unit, the reaction conditions are: gas flow rate of 100–200,000 m³ / s. 3 / h, solid flow rate is 1kg~100t / h, particle size is 20~1000μm;

[0037] When the carbonate hydrogenation reactor is a two-tower series unit, the overall reaction conditions are: gas flow rate of 150–250,000 m³ / h. 3 / h, solid flow rate is 1.5kg~200t / h, particle size is 20~1000μm;

[0038] Through the above process steps, the volume ratio of H2 / CO / CO2 in the product synthesis gas is 16 / 2 / 1 to 24 / 2 / 1.

[0039] Preferably, in the methanol production process, the reaction conditions of the methanol reactor are as follows: pressure of 3MPa to 30MPa and temperature of 220 to 400℃.

[0040] The crude methanol obtained after gas-liquid separation is purified by distillation column, and the mass percentage of methanol in the purified methanol is 99-99.99%.

[0041] The hydrogen-rich gas (85%–95% H2) after gas-liquid separation is reused and mixed with fresh hydrogen in the hydrogen-rich gas mixer (16). The volume percentage of hydrogen in the mixed gas is 90%–99%, and it enters the carbonate hydrogenation reactor through the hydrogen inlet.

[0042] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0043] (1) The present invention provides a low-carbon production system for producing metal oxides and methanol from carbonates with high efficiency and hydrogen assistance. The synthesis gas product of the original carbonate hydrogenation conversion process is further converted into methanol product with higher added value, realizing the efficient co-production of metal oxides and methanol. At the same time, based on the physical property of easy liquefaction of methanol, the unreacted hydrogen-rich gas and methanol can be effectively separated through simple and convenient gas-liquid separation. The hydrogen-rich gas can be reused in the carbonate hydrogenation conversion process, thereby greatly improving the hydrogen utilization efficiency and thus improving the competitiveness and application prospects of the entire carbon emission reduction system in terms of environment, energy and economy. It successfully solves the bottleneck problem of the current carbonate hydrogenation refining technology.

[0044] On the other hand, under the background of carbon neutrality, the research and production of renewable methanol based on CO2 capture and utilization (CCU) technology, using CO2 captured from green hydrogen and carbonaceous flue gas, is gaining increasing attention. However, its complex production process, including CO2 capture, purification, compression, transportation, and hydroconversion, greatly limits the large-scale industrial production of renewable methanol. The production system provided by this invention uses carbonate as raw material and efficiently, with low carbon emissions and energy saving, co-produces metal oxides and methanol through direct hydrogenation conversion, significantly simplifying the production process of renewable methanol and improving its energy utilization efficiency.

[0045] (2) The present invention provides a low-carbon production method for producing metal oxides and methanol from carbonates with hydrogenation. By coupling the carbonate hydrogenation conversion reaction in series with the syngas methanol production reaction, the direct carbon dioxide emissions generated by the decomposition of carbonates in the original production process are transformed into high-value-added methanol products. At the same time, the timely in-situ hydrogenation conversion of CO2 during the carbonate hydrogenation conversion process promotes the decomposition of carbonates both thermodynamically and kinetically, allowing it to proceed faster and more fully at a lower temperature, thereby significantly reducing process energy consumption and indirect carbon dioxide emissions generated by energy combustion.

[0046] To further illustrate the aforementioned beneficial effects, we took the hydrogenation of magnesite (MgCO3) to magnesium oxide (MgO) and methanol as an example, conducting process simulation at a pilot-scale capacity of 2400 tons / year of magnesite. We compared and evaluated the traditional magnesite thermal decomposition coupled CCU technology (including the low-temperature CO2 capture process of amine solution and the subsequent CO2 hydrogenation to methanol process) at the same scale, focusing on energy consumption, carbon emissions, and economic feasibility (Table 1). Because multiple endothermic reactions, such as MgCO3 hydrogenation conversion and decomposition, are integrated into a single carbonate hydrogenation reactor, the energy losses caused by cooling and capturing high-temperature flue gas followed by catalytic conversion of enriched CO2, as well as the enormous energy required for amine solution regeneration, are avoided in the traditional CCU process. The energy consumption of the magnesite hydrogenation to magnesium oxide and methanol process (47 MJ / kg methanol) is significantly lower than that of the traditional magnesite thermal decomposition coupled CCU process (60 MJ / kg methanol). More importantly, the high H2 / CO ratio (8–12) of the syngas ensures efficient subsequent methanol production and hydrogen-rich gas reuse. Therefore, the lower energy demand, higher hydrogen utilization efficiency, and methanol production efficiency make the magnesite hydrogenation to magnesium oxide and methanol process (1.1 kg CO2 / kg methanol, 1.3 yuan / kg methanol) more effective in carbon reduction and economically feasible than the traditional magnesite thermal decomposition coupled CCU process (3.5 kg CO2 / kg methanol, -1.1 yuan / kg methanol). Attached Figure Description

[0047] Figure 1 A schematic diagram of a low-carbon production system for producing metal oxides and methanol from carbonates using high efficiency hydrogen-assisted methods provided by this invention.

[0048] Figure 2 A schematic diagram of the structure of the carbonate hydrogenation reactor with a dual-tower series unit provided by the present invention;

[0049] Symbol explanation:

[0050] Figure 1 : 1-Carbonate hydrogenation reactor ( Figure 1 For a single tower unit, Figure 2 1-(Double tower series unit), 2-Cyclone separator, 3-First cooler, 4-First heat exchanger, 5-Second cooler, 6-Third cooler, 7-First gas-liquid separator, 8-Turbine compressor, 9-Second heat exchanger, 10-Methanol reactor, 11-Pressure reducing valve, 12-Fourth cooler, 13-Fifth cooler, 14-Second gas-liquid separator, 15-Distillation column, 16-Mixer.

[0051] Figure 217-First dual-way control valve, 18-Three-way control valve, 19-Second dual-way control valve, 20-First carbonate hydrogenation reactor, 21-Second carbonate hydrogenation reactor. Detailed Implementation

[0052] The implementation of the present invention will be described in detail below with reference to the embodiments of the present invention. The following embodiments are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments. The reagents and raw materials used in the present invention are all commercially available or can be prepared according to the methods in the literature. At the same time, the embodiments do not include a detailed description of conventional methods.

[0053] The purpose of this invention is to provide a low-carbon production system and method for producing metal oxides and methanol from carbonates using high-efficiency hydrogen-assisted methods. This system efficiently co-produces metal oxides and methanol through carbonate hydrogenation, achieving carbon emission reduction and high-value conversion of CO2 in energy-intensive industries using carbonates as raw materials. Simultaneously, through a low-cost, low-energy gas-liquid separation method, hydrogen-rich reaction gas and methanol products can be efficiently separated and reused in the carbonate hydrogenation process, significantly improving hydrogen utilization efficiency and reducing energy consumption, costs, and carbon dioxide emissions associated with hydrogen supply. This provides a practical strategy for energy conservation, emission reduction, and efficiency improvement in energy-intensive industries such as steel, refractory materials, and cement.

[0054] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] like Figure 1 As shown, the high-efficiency hydrogen-assisted low-carbon production system for producing metal oxides and methanol from carbonates provided by the present invention includes: a carbonate hydrogenation reactor 1, a cyclone separator 2, a first cooler 3, a first heat exchanger 4, a second cooler 5, a third cooler 6, a first gas-liquid separator 7, a turbine compressor 8, a second heat exchanger 9, a methanol reactor 10, a pressure reducing valve 11, a fourth cooler 12, a fifth cooler 13, a second gas-liquid separator 14, a distillation column 15, and a mixer 16.

[0056] Specifically, carbonates react completely with preheated mixed hydrogen-rich gas in carbonate hydrogenation reactor 1 to generate metal oxides and syngas with a high H2 / CO ratio. Further, the two are separated by cyclone separator 2. The metal oxides are discharged from the system after heat recovery in the first cooler 3, while the syngas is fully preheated by the mixed hydrogen-rich gas in the first heat exchanger 4 and then further cooled by the second cooler 5 and the third cooling zone 6 to recover residual heat. The recovered heat is used to produce low-pressure steam, medium-pressure steam, or high-pressure steam for power generation, heating, or sale. The cooled syngas is dehydrated by the first gas-liquid separator 7 and pressurized to the required pressure by the turbine compressor 8 before being input into the second heat exchanger 9. After being fully preheated by the outlet product gas of the methanol reactor 10, it is used for methanol synthesis.

[0057] The heat released during methanol synthesis is promptly recovered via heat exchange tubes embedded in the reaction bed to produce low-pressure, medium-pressure, or high-pressure steam for power generation, heating, or sale. The outlet product gas after heat exchange continues to be depressurized to the required pressure via the pressure reducing valve 11. The depressurized outlet product gas then passes sequentially through the fourth cooler 12 and the fifth cooler 13 to recover heat and further cool, with the recovered heat used in the reboiler of the distillation column 15. The second gas-liquid separator 14 separates the cooled outlet product gas into crude methanol and hydrogen-rich gas. The distillation column 15 further separates and purifies the crude methanol into refined methanol. The hydrogen-rich gas is mixed with a small amount of supplemental hydrogen in the mixer 16 to obtain a mixed hydrogen-rich gas, which is then reused in the carbonate hydrogenation conversion process.

[0058] like Figure 2 As shown, in order to further improve hydrogen utilization efficiency and ensure efficient production of methanol, when a single tower unit cannot meet the target H2 / CO volume ratio (8-12) in the syngas at the outlet, the carbonate hydrogenation reactor adopts a dual-tower series unit, including: a first dual-way control valve 1, a three-way control valve 2, a second dual-way control valve 3, a first carbonate hydrogenation reactor 4, and a second carbonate hydrogenation reactor 5.

[0059] Specifically, the first dual-way control valve 1 closes the external passage, and the mixed hydrogen-rich gas first enters the first carbonate hydrogenation reactor 4 through the three-way control valve 2 for hydrogenation reaction. The low-CO-concentration hydrogen-rich gas output from the first carbonate hydrogenation reactor 4 continues to be used for the hydrogenation reaction in the second carbonate hydrogenation reactor 5 to further improve the CO concentration and hydrogen utilization efficiency in the final output syngas. The high-CO-concentration syngas is output externally through the second dual-way control valve 3. Due to the decrease in hydrogen concentration in the reaction gas and the lag in pipeline transportation, the first carbonate hydrogenation reactor 4 will complete the carbonate hydrogenation conversion before the second carbonate hydrogenation reactor 5. At this time, the three-way control valve 2 switches the gas path direction to transport the mixed hydrogen-rich gas to the second carbonate hydrogenation reactor 5, the second dual-way control valve 3 closes the external passage, and the first dual-way control valve 1 opens the external passage. After the fresh carbonate in the first carbonate hydrogenation reactor 4 is fed, the above hydrogenation conversion process is repeated.

[0060] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0061] Example 1 (Axial fixed-bed reactor, single tower unit, calcium carbonate)

[0062] Calcium carbonate (particle size 40μm) is fed at a rate of 60t / h in a single operation, mixed with hydrogen-rich gas at a rate of 100,000m³. 3A continuous feed of calcium carbonate is introduced into an axially fixed-bed reactor-type carbonate hydroconversion reactor 1 at 700°C and 1 atm. Calcium carbonate is completely decomposed into calcium oxide, generating syngas with a volume ratio of H2 / CO / CO2 of approximately 20 / 2 / 1. The two are then separated by a cyclone separator 2. The calcium oxide is cooled to 260°C by a first cooler 3 before being output from the system, and the recovered heat is used to generate high-pressure steam for power generation, heating, or sale. The syngas is preheated to 450°C by a first heat exchanger 4 and then further cooled to 35°C by a second cooler 5 and a third cooler 6, respectively. The recovered heat is used to produce medium-pressure steam for power generation, heating, or sale. The cooled syngas is then dehydrated by a first gas-liquid separator 7 and pressurized by a turbine compressor 8. After reaching 5 MPa, the gas is fed into the second heat exchanger 9. The product gas from the methanol reactor 10 is then fully preheated to 210°C before being used for methanol synthesis (250°C, 5 MPa). To prevent sintering of the methanol catalyst, the heat released during methanol synthesis is promptly recovered via heat exchange tubes embedded in the reaction bed to produce low-pressure steam for power generation, heating, or sale. The product gas is further depressurized to 1 atm via pressure reducing valve 11. After depressurization, the product gas passes through the fourth cooler 12 and the fifth cooler 13 to recover heat and further cool to 50°C. The recovered heat is used in the reboiler of the distillation column 15. The second gas-liquid separator 14 separates the cooled product gas into crude methanol and hydrogen-rich gas (94% hydrogen content). The distillation column 15 further separates and purifies the crude methanol to 99.99%. wt % refined methanol; hydrogen-rich gas and a small amount of supplementary hydrogen are mixed in mixer 16 to obtain mixed hydrogen-rich gas (hydrogen content of 98%), which is then reused in the carbonate hydrogenation conversion process.

[0063] Example 2 (Axial fixed-bed reactor, single tower unit, magnesium carbonate)

[0064] Magnesium carbonate (particle size 35μm) is fed in a single batch at 280kg / h, mixed with hydrogen-rich gas at 560m³ / h. 3A continuous feed of magnesium carbonate is introduced into an axially fixed-bed reactor-type carbonate hydroconversion reactor 1 at 550°C and 1 atm. Magnesium carbonate is completely decomposed into magnesium oxide, generating syngas with a volume ratio of H2 / CO / CO2 of approximately 16 / 2 / 1. Further, the two are separated by a cyclone separator 2. The magnesium oxide is cooled to 130°C by a first cooler 3 before being output from the system, with the recovered heat used to generate low-pressure steam for power generation, heating, or sale. The syngas is preheated to 300°C by a first heat exchanger 4 and then further cooled to 35°C by a second cooler 5 and a third cooler 6, with the recovered heat used to generate low-pressure steam for power generation, heating, or sale. The cooled syngas is then dehydrated by a first gas-liquid separator 7 and pressurized by a turbine compressor 8. After passing through the second heat exchanger 9 at 5 MPa, the product gas from the methanol reactor 10 is preheated to 180°C before being used for methanol synthesis (250°C, 5 MPa). To prevent sintering of the methanol catalyst, the heat released during methanol synthesis is promptly recovered via heat exchange tubes embedded in the reaction bed to produce low-pressure steam for power generation, heating, or sale. The product gas is then further depressurized to 1 atm via pressure reducing valve 11. After depressurization, the product gas passes through the fourth cooler 12 and the fifth cooler 13 to recover heat and further cool to 50°C. The recovered heat is used in the reboiler of the distillation column 15. The second gas-liquid separator 14 separates the cooled product gas into crude methanol and hydrogen-rich gas (94% hydrogen content). The distillation column 15 further separates and purifies the crude methanol to 99.99%. wt % refined methanol; hydrogen-rich gas and a small amount of supplementary hydrogen are mixed in mixer 16 to obtain mixed hydrogen-rich gas (hydrogen content of 99%), which is then reused in the carbonate hydrogenation conversion process.

[0065] Example 3 (Axial fixed-bed reactor, single-tower unit, ferrous carbonate)

[0066] Ferrous carbonate (particle size 25μm) is fed at a rate of 5t / h in a single operation, mixed with hydrogen-rich gas at a rate of 6000m³. 3A continuous feedstock is introduced into a carbonate hydroconversion reactor 1 (an axially fixed-bed reactor type) at 500°C and 1.1 atm. Ferrous carbonate is completely decomposed and reduced to iron, generating syngas with a H2 / CO / CO2 volume ratio of approximately 18 / 2 / 1. Further, the two are separated by a cyclone separator 2. The iron is cooled to 130°C by a first cooler 3 before being output from the system, with the recovered heat used to generate low-pressure steam for power generation, heating, or sale. The syngas is preheated to 250°C by a first heat exchanger 4 and then further cooled to 35°C by a second cooler 5 and a third cooler 6, with the recovered heat used to generate low-pressure steam for power generation, heating, or sale. The cooled syngas is then dehydrated by a first gas-liquid separator 7 and pressurized to 5MΩ by a turbine compressor 8. After passing through the second heat exchanger 9, the product gas from the methanol reactor 10 is preheated to 200°C before being used for methanol synthesis (240°C, 5MPa). To prevent sintering of the methanol catalyst, the heat released during methanol synthesis is promptly recovered via heat exchange tubes embedded in the reaction bed to produce low-pressure steam for power generation, heating, or sale. The product gas is further depressurized to 1.1 atm via pressure reducing valve 11. After depressurization, the product gas passes through the fourth cooler 12 and the fifth cooler 13 to recover heat and further cool to 50°C. The recovered heat is used in the reboiler of the distillation column 15. The second gas-liquid separator 14 separates the cooled product gas into crude methanol and hydrogen-rich gas (92.9% hydrogen content). The distillation column 15 further separates and purifies the crude methanol to 99.99%. wt % refined methanol; hydrogen-rich gas and a small amount of supplementary hydrogen are mixed in mixer 16 to obtain mixed hydrogen-rich gas (hydrogen content of 99%), which is then reused in the carbonate hydrogenation conversion process.

[0067] Example 4 (turbulent fluidized bed reactor, single tower unit, calcium carbonate)

[0068] Calcium carbonate (particle size 100 μm) is introduced at a rate of 70 t / h from the carbonate inlet at the top of the reactor, mixed with hydrogen-rich gas at a rate of 130,000 m³ / h. 3A continuous hydrogen inlet is fed into a carbonate hydroconversion reactor 1 (a turbulent fluidized bed reactor type) at 720°C and 1 atm. Calcium carbonate is completely decomposed into calcium oxide, generating syngas with a H2 / CO / CO2 volume ratio of approximately 2:1 / 2 / 1. Further, the two are separated by a cyclone separator 2. The calcium oxide is cooled to 260°C by a first cooler 3 before being output from the system, with the recovered heat used to generate high-pressure steam for power generation, heating, or sale. The syngas is preheated to 460°C by a first heat exchanger 4 and then further cooled to 35°C by a second cooler 5 and a third cooler 6, with the recovered heat used to produce medium-pressure steam for power generation, heating, or sale. The cooled syngas is then dehydrated by a first gas-liquid separator 7 and processed by a turbine compressor 8. After being pressurized to 25 MPa, the gas is fed into the second heat exchanger 9. The outlet product gas from the methanol reactor 10 is then fully preheated to 340°C before being used for methanol synthesis (380°C, 25 MPa). To prevent sintering of the methanol catalyst, the reaction heat released during methanol synthesis is promptly recovered via heat exchange tubes embedded in the reaction bed to produce high-pressure steam for power generation, heating, or sale. The outlet product gas is further depressurized to 1 atm via pressure reducing valve 11. The depressurized outlet product gas then passes sequentially through the fourth cooler 12 and the fifth cooler 13 to recover heat and further cool to 50°C. The recovered heat is used in the reboiler of the distillation column 15. The second gas-liquid separator 14 separates the cooled outlet product gas into crude methanol and hydrogen-rich gas (hydrogen content 93.8%). The distillation column 15 further separates and purifies the crude methanol to 99.99%. wt % refined methanol; hydrogen-rich gas and a small amount of supplementary hydrogen are mixed in mixer 16 to obtain mixed hydrogen-rich gas (hydrogen content of 98%), which is then reused in the carbonate hydrogenation conversion process.

[0069] Example 5 (turbulent fluidized bed reactor, single tower unit, magnesium carbonate)

[0070] Magnesium carbonate (particle size 110 μm) is mixed with hydrogen-rich gas at a rate of 1 t / h at a flow rate of 1900 m³ / h. 3The feed is continuously fed into the carbonate hydrogenation conversion reactor 1 (a turbulent fluidized bed reactor type) at the corresponding inlet at the bottom of the reactor, and the reaction is carried out at 560℃ and 1 atm. Magnesium carbonate is completely decomposed into magnesium oxide and syngas with a volume ratio of H2 / CO / CO2 of approximately 19 / 2 / 1. Further, the two are separated by a cyclone separator 2. The magnesium oxide is cooled to 130℃ by a first cooler 3 before being output from the system, and the recovered heat is used to generate low-pressure steam for power generation, heating, or sale. The syngas is preheated to 300℃ by a first heat exchanger 4 and then further cooled to 35℃ by a second cooler 5 and a third cooler 6, respectively. The recovered heat is used to produce low-pressure steam for power generation, heating, or sale. The cooled syngas is then dehydrated by a first gas-liquid separator 7 and compressed by a turbine. The gas is pressurized to 25 MPa by the pump 8 and then fed into the second heat exchanger 9. The outlet product gas from the methanol reactor 10 is fully preheated to 340°C before being used for methanol synthesis (390°C, 25 MPa). To prevent sintering of the methanol catalyst, the heat released during methanol synthesis is promptly recovered via heat exchange tubes embedded in the reaction bed to produce high-pressure steam for power generation, heating, or sale. The outlet product gas is further depressurized to 1 atm by the pressure reducing valve 11. After depressurization, the outlet product gas passes sequentially through the fourth cooler 12 and the fifth cooler 13 to recover heat and further cool to 50°C. The recovered heat is used in the reboiler of the distillation column 15. The second gas-liquid separator 14 separates the cooled outlet product gas into crude methanol and hydrogen-rich gas (94% hydrogen content). The distillation column 15 further separates and purifies the crude methanol to 99.99%. wt % refined methanol; hydrogen-rich gas and a small amount of supplementary hydrogen are mixed in mixer 16 to obtain mixed hydrogen-rich gas (hydrogen content of 99%), which is then reused in the carbonate hydrogenation conversion process.

[0071] Example 6 (turbulent fluidized bed reactor, single tower unit, ferrous carbonate)

[0072] Ferrous carbonate (particle size 100μm) is produced at a rate of 12 t / h, mixed with hydrogen-rich gas at a rate of 18000 m³ / h. 3The feed is continuously fed into the carbonate hydrogenation conversion reactor 1 (a turbulent fluidized bed reactor type) at the corresponding inlet at the bottom of the reactor, and the reaction is carried out at 520℃ and 1.1 atm. Ferrous carbonate is completely decomposed and reduced to iron, generating syngas with a volume ratio of H2 / CO / CO2 of approximately 20 / 2 / 1. Further, the two are separated by a cyclone separator 2. The iron is cooled to 130℃ by a first cooler 3 before being output from the system, and the recovered heat is used to generate low-pressure steam for power generation, heating, or sale. The syngas is fully preheated to 250℃ by a first heat exchanger 4 and then further cooled to 35℃ by a second cooler 5 and a third cooler 6, respectively. The recovered heat is used to produce low-pressure steam for power generation, heating, or sale. The cooled syngas is then dehydrated by a first gas-liquid separator 7 and fed by a turbine compressor 8. After being pressurized to 25 MPa, the gas is fed into the second heat exchanger 9. The outlet product gas from the methanol reactor 10 is then fully preheated to 340°C before being used for methanol synthesis (380°C, 25 MPa). To prevent sintering of the methanol catalyst, the heat released during methanol synthesis is promptly recovered via heat exchange tubes embedded in the reaction bed to produce high-pressure steam for power generation, heating, or sale. The outlet product gas is further depressurized to 1.1 atm via pressure reducing valve 11. The depressurized outlet product gas then passes through the fourth cooler 12 and the fifth cooler 13 to recover heat and further cool to 50°C. The recovered heat is used in the reboiler of the distillation column 15. The second gas-liquid separator 14 separates the cooled outlet product gas into crude methanol and hydrogen-rich gas (hydrogen content 93.7%). The distillation column 15 further separates and purifies the crude methanol to 99.99%. wt % refined methanol; hydrogen-rich gas and a small amount of supplementary hydrogen are mixed in mixer 16 to obtain mixed hydrogen-rich gas (hydrogen content of 99%), which is then reused in the carbonate hydrogenation conversion process.

[0073] Example 7 (Axial fixed-bed reactor, twin-tower series unit, calcium carbonate)

[0074] Mixed hydrogen-rich gas at 140,000 m 3 A continuous feed of calcium carbonate (40 μm particle size) is introduced into a twin-tower series carbonate hydrogenation reactor 1 of the axial fixed-bed reactor type. The first and second carbonate hydrogenation reactors are each fed with a single feed of 50 t / h of calcium carbonate. Figure 2The reaction is carried out at 700℃ and 1 atm for 1 hour. Calcium carbonate is completely decomposed into calcium oxide, generating syngas with a volume ratio of H2 / CO / CO2 of approximately 16 / 2 / 1. Further, the two are separated by a cyclone separator 2. The calcium oxide is cooled to 260℃ by a first cooler 3 before being output from the system, and the recovered heat is used to generate high-pressure steam for power generation, heating, or sale. The syngas is preheated to 450℃ by a first heat exchanger 4 and then further cooled to 35℃ by a second cooler 5 and a third cooler 6, respectively. The recovered heat is used to produce medium-pressure steam for power generation, heating, or sale. The cooled syngas is dehydrated by a first gas-liquid separator 7 and pressurized to 5MPa by a turbine compressor 8 before being input into the system. The second heat exchanger 9 preheats the outlet product gas from the methanol reactor 10 to 180°C before it is used for methanol synthesis (220°C, 5MPa). To prevent sintering of the methanol catalyst, the reaction heat released during methanol synthesis is promptly recovered via heat exchange tubes embedded in the reaction bed to produce low-pressure steam for power generation, heating, or sale. The outlet product gas is further depressurized to 1 atm via pressure reducing valve 11. After depressurization, the outlet product gas passes through the fourth cooler 12 and the fifth cooler 13 to recover heat and further cool to 50°C. The recovered heat is used in the reboiler of the distillation column 15. The second gas-liquid separator 14 separates the cooled outlet product gas into crude methanol and hydrogen-rich gas (hydrogen content 94%). The distillation column 15 further separates and purifies the crude methanol to 99.99%. wt % refined methanol; hydrogen-rich gas and a small amount of supplementary hydrogen are mixed in mixer 16 to obtain mixed hydrogen-rich gas (hydrogen content of 99%), which is then reused in the carbonate hydrogenation conversion process.

[0075] Example 8 (Turbulent fluidized bed reactor, twin-tower series unit, calcium carbonate)

[0076] Mixed hydrogen-rich gas at 170,000 m 3 A continuous feed of calcium carbonate (particle size 100 μm) is introduced at the hydrogen inlet at the bottom of the reactor into a twin-tower series carbonate hydrogenation reactor of the turbulent fluidized bed reactor type. The first and second carbonate hydrogenation reactors are each continuously fed with calcium carbonate (particle size 100 μm) at the carbonate inlet at the top of the reactor at a rate of 55 t / h. Figure 2The reaction takes place at 720℃ and 1 atm; calcium carbonate is completely decomposed into calcium oxide and syngas with a volume ratio of H2 / CO / CO2 of approximately 18 / 2 / 1; further, the two are separated by cyclone separator 2, where calcium oxide is cooled to 260℃ by first cooler 3 before being output from the system, and the recovered heat is used to generate high-pressure steam for power generation, heating, or sale; the syngas is fully preheated to 460℃ by first heat exchanger 4 and then further cooled to 35℃ by second cooler 5 and third cooler 6 respectively, where the recovered heat is used to produce medium-pressure steam for power generation, heating, or sale; the cooled syngas is dehydrated by first gas-liquid separator 7 and pressurized to 25MPa by turbine compressor 8 before being input into second heat exchanger. The product gas from the methanol reactor 10 is preheated to 340°C before being used for methanol synthesis (380°C, 25MPa). To prevent sintering of the methanol catalyst, the heat released during methanol synthesis is promptly recovered via heat exchange tubes embedded in the reaction bed to produce high-pressure steam for power generation, heating, or sale. The product gas is further depressurized to 1 atm via pressure reducing valve 11. After depressurization, the product gas passes through fourth cooler 12 and fifth cooler 13 to recover heat and further cool to 50°C. The recovered heat is used in the reboiler of distillation column 15. Second gas-liquid separator 14 separates the cooled product gas into crude methanol and hydrogen-rich gas (93% hydrogen content). Distillation column 15 further separates and purifies the crude methanol to 99.99%. wt % refined methanol; hydrogen-rich gas and a small amount of supplementary hydrogen are mixed in mixer 16 to obtain mixed hydrogen-rich gas (hydrogen content of 98%), which is then reused in the carbonate hydrogenation conversion process.

[0077] Practical application examples

[0078] Taking the process of hydrogenating magnesite (MgCO3) to produce magnesium oxide (MgO) and methanol as an example, the process simulation was carried out using the method in Example 2 on a pilot-scale scale with a magnesite processing capacity of 2400 tons / year.

[0079] Using the traditional magnesite thermal decomposition coupled CCU technology of the same scale, including the low-temperature CO2 capture process of amine solution and the subsequent CO2 hydrogenation to methanol process, as a reference, we compare and evaluate it from three aspects: energy consumption, carbon emissions and economic feasibility (Table 1).

[0080] Table 1. Comparative Analysis of Energy Consumption, Net CO2 Emissions, and Benefits per Unit of Methanol Production between the Magnesite Hydrogenation to Magnesium Oxide and the Traditional Magnesite Thermal Decomposition Coupled CCU Process.

[0081]

[0082] 1The conditions for carbonate hydrogenation reaction are 550℃ and 1 atm; the conditions for methanol production are 250℃ and 5 MPa.

[0083] 2 Traditional carbonate thermal decomposition conditions are 700℃ and 1 atm; methanol production conditions are 250℃ and 5 MPa.

[0084] 3 Energy consumption includes electricity consumption, coal consumption, and energy consumption required for hydrogen production.

[0085] 4 Net CO2 emissions take into account process carbon emissions, hydrogen and electricity production carbon emissions, coal combustion carbon emissions, and CO2 emissions from byproducts (magnesium oxide, methanol) and process energy recovery.

[0086] 5 Benefit considerations include: ① Raw material costs, including hydrogen, magnesite, amine solvents, methanol catalysts, etc.; ② Utility costs, including electricity, coal, and circulating cooling water; ③ Product revenue, including magnesium oxide, methanol, and recovered low-pressure steam; ④ Carbon tax.

[0087] By integrating multiple endothermic reactions, such as MgCO3 hydrogenation conversion and decomposition, into a single carbonate hydrogenation reactor, the energy losses associated with traditional CCU processes—namely, the energy required for cooling and capturing high-temperature flue gas followed by catalytic conversion of enriched CO2, and the enormous energy demands of amine solution regeneration—are avoided. This significantly reduces the energy consumption of the magnesite hydrogenation to magnesium oxide and methanol process (47 MJ / kg methanol) compared to the traditional magnesite thermal decomposition coupled with CCU process (60 MJ / kg methanol). More importantly, the high H2 / CO ratio (8–12) of the syngas ensures efficient subsequent methanol production and hydrogen-rich gas reuse. Therefore, the lower energy requirements, higher hydrogen utilization efficiency, and methanol production efficiency make the magnesite hydrogenation to magnesium oxide and methanol process (1.1 kg CO2 / kg methanol, 1.3 yuan / kg methanol) more effective in carbon reduction and economically feasible compared to the traditional magnesite thermal decomposition coupled with CCU process (3.5 kg CO2 / kg methanol, -1.1 yuan / kg methanol).

[0088] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A low-carbon production system for producing metal oxides and methanol from hydrogen-assisted carbonates, characterized in that, include: The carbonate hydrogenation reactor (1) is equipped with a carbonate inlet and a hydrogen inlet. The carbonate reacts completely with the preheated mixed hydrogen-rich gas to generate metal oxides and syngas with a volume ratio of H2:CO of 8~12. The outlet is connected to a metal oxide and syngas separator (2). The syngas outlet of the separator is connected to a syngas post-processing system, and the metal oxide outlet is connected to a first cooler (3) for cooling the generated metal oxides. If the volume ratio of H2 to CO in the syngas is 8 to 12, a multi-tower parallel configuration with a single tower unit is adopted; if a single tower unit cannot meet the requirement of an H2 to CO volume ratio of 8 to 12 in the syngas, a multi-tower parallel configuration with a dual-tower series unit is adopted. The syngas post-processing system includes a first heat exchanger (4), a second cooler (5), a third cooler (6), a first gas-liquid separator (7), a turbine compressor (8), and a second heat exchanger (9) connected in sequence. The inlet of the first heat exchanger (4) is connected to both the syngas outlet and the hydrogen-rich gas mixer (16), and the outlet is connected to the carbonate hydrogenation reactor (1) and the second cooler (5), respectively. After the syngas is fully preheated and mixed with the hydrogen-rich gas by the first heat exchanger (4), it continues to pass through the second cooler (5) and the third cooler (6) to recover residual heat and further cool. The cooled syngas is dehydrated by the first gas-liquid separator (7) and pressurized to the required pressure by the turbine compressor (8) before being input into the second heat exchanger (9). After being fully preheated by the product gas at the outlet of the methanol reactor (10), it is used for methanol synthesis. The methanol reaction system includes a methanol reactor (10), a pressure reducing valve (11), a fourth cooler (12), a fifth cooler (13), a second gas-liquid separator (14), and a distillation column (15) connected in sequence. The methanol reactor (10) is equipped with heat exchange tubes to recover heat and avoid hot spot effects. The outlet product gas after heat exchange in the second heat exchanger (9) is depressurized to the required pressure by the pressure reducing valve (11), and then passes through the fourth cooler (12) and the fifth cooler (13) in sequence to recover heat and further cool. The recovered heat is used for the reboiler of the distillation column (15). The top outlet of the second gas-liquid separator (14) is connected to the hydrogen-rich gas mixer (16), which separates the cooled outlet product gas into crude methanol and hydrogen-rich gas. The hydrogen-rich gas is mixed with a small amount of supplementary hydrogen in the hydrogen-rich gas mixer (16) to obtain mixed hydrogen-rich gas, which is then reused in the carbonate hydrogenation reactor (1). The distillation column (15) further separates and purifies the crude methanol into refined methanol.

2. The low-carbon production system for hydrogen-assisted carbonate to metal oxides and methanol according to claim 1, characterized in that: in, The carbonate hydrogenation reactor (1) is selected from one or a combination of two of the following: fluidized bed, moving bed, and fixed bed reactors.

3. The low-carbon production system for producing metal oxides and methanol from hydrogen-assisted carbonates according to claim 2, characterized in that: in, The fluidized bed reactor is a bubbling fluidized bed, a turbulent fluidized bed, a dense phase transport bed, or a dilute phase transport bed; The fixed-bed reactor is an axial fixed-bed reactor, a radial fixed-bed reactor, or a tubular fixed-bed reactor.

4. The low-carbon production system for producing metal oxides and methanol from hydrogen-assisted carbonates according to claim 1, characterized in that: in, When the carbonate hydrogenation reactor adopts a dual-tower series unit, it includes a first dual-way control valve (17), a three-way control valve (18), and a second dual-way control valve (19) connected in series, as well as a first carbonate hydrogenation reactor (20) and a second carbonate hydrogenation reactor (21) connected in series. The three-way control valve (18) is connected to the hydrogen inlet of both the first carbonate hydrogenation reactor (20) and the second carbonate hydrogenation reactor (21), and the first two-way control valve (17) and the second two-way control valve (19) are connected to the synthesis gas outlet of both the first carbonate hydrogenation reactor (20) and the second carbonate hydrogenation reactor (21), respectively.

5. A method for producing metal oxides and methanol from hydrogen-assisted carbonates using the production system described in any one of claims 1 to 4, characterized in that, Includes the following steps: Carbonate and preheated mixed hydrogen-rich gas are added to the carbonate hydrogenation reactor (1) through the carbonate inlet and the hydrogen inlet, respectively. The reaction generates metal oxide and syngas with a volume ratio of H2:CO of 8~12. After separation by the metal oxide and syngas separator (2), the metal oxide is discharged from the system after recovering heat through the first cooler (3). After the synthesis gas is fully preheated and mixed with hydrogen-rich gas by the first heat exchanger (4), it continues to pass through the second cooler (5) and the third cooler (6) to recover residual heat and further cool. The cooled synthesis gas is then dehydrated by the first gas-liquid separator (7) and pressurized to the required pressure by the turbine compressor (8) before being input into the second heat exchanger (9). After being fully preheated by the outlet product gas of the methanol reactor (10), it is used for methanol synthesis. The outlet product gas generated in the methanol reactor (10) is reduced to the required pressure by the pressure reducing valve (11) after heat exchange, and then passes through the fourth cooler (12) and the fifth cooler (13) in sequence to recover heat and further cool. The recovered heat is used for the reboiler of the distillation column (15). The cooled outlet product gas is separated into crude methanol and hydrogen-rich gas by the second gas-liquid separator (14). The hydrogen-rich gas is mixed with a small amount of fresh hydrogen in the hydrogen-rich gas mixer (16) to obtain mixed hydrogen-rich gas, which is then reused in the carbonate hydrogenation reactor (1). The crude methanol is further separated and purified into refined methanol by the distillation column (15).

6. The method for producing metal oxides and methanol from hydrogen-assisted carbonates according to claim 5, characterized in that: in, When a single-tower unit cannot meet the requirement of an H2 / CO volume ratio of 8-12 in the outlet syngas, a dual-tower series unit is used; the operating steps are as follows: First, close the external passage of the first double-way control valve (17). The mixed hydrogen-rich gas enters the first carbonate hydrogenation reactor (20) through the three-way control valve (18) for hydrogenation reaction. The low CO concentration hydrogen-rich gas output from the first carbonate hydrogenation reactor (20) is used for hydrogenation reaction in the second carbonate hydrogenation reactor (21). The high CO concentration synthesis gas is output externally through the second double-way control valve (19). Due to the decrease in hydrogen concentration in the reaction gas and the lag in pipeline transportation, the first carbonate hydrogenation reactor (20) will complete the carbonate hydrogenation conversion before the second carbonate hydrogenation reactor (21). At this time, the three-way control valve (18) switches the gas path direction to transport the mixed hydrogen-rich gas to the second carbonate hydrogenation reactor (21), the second double-way control valve (19) closes the external passage, and the first double-way control valve (17) opens the external passage. After the fresh carbonate in the first carbonate hydrogenation reactor (20) is fed, the above hydrogenation conversion process is repeated.

7. The method for producing metal oxides and methanol from hydrogen-assisted carbonates according to claim 5, characterized in that: in, The carbonate is selected from calcium carbonate, magnesium carbonate, ferrous carbonate, or natural minerals with these as the main components. Hydrogen is produced from fossil fuels, nuclear power water electrolysis, nuclear high-temperature reactor thermochemical hydrogen production, renewable energy power generation water electrolysis, photocatalytic water splitting, biological reforming, or algal photosynthesis.

8. The method for producing metal oxides and methanol from hydrogen-assisted carbonates according to claim 7, characterized in that: in, The natural ore is selected from one or more combinations of dolomite, calcite, limestone, magnesite, siderite, and ferrodolomite; the carbonate is fed into the carbonate hydrogenation reactor in a one-time, batch, or continuous manner.

9. The method for producing metal oxides and methanol from hydrogen-assisted carbonates according to claim 5, characterized in that: in, The reaction conditions of the carbonate hydrogenation reactor are as follows: pressure is atmospheric pressure ~ 1 MPa, and temperature is 350℃ ~ 1200℃; When the carbonate hydrogenation reactor is a single-tower unit, the reaction conditions are: gas flow rate of 100~200000 m³ / h. 3 / h, solid flow rate is 1kg~100 t / h, particle size is 20~1000 μm; When the carbonate hydrogenation reactor is a two-tower series unit, the overall reaction conditions are: gas flow rate of 150~250000 m³ / h. 3 / h, solid flow rate is 1.5kg~200 t / h, particle size is 20~1000 μm; The volume ratio of H2:CO:CO2 in the outlet synthesis gas is 16:2:1 to 24:2:

1.

10. The method for producing metal oxides and methanol from hydrogen-assisted carbonates according to claim 5, Its features are: The reaction conditions of the methanol reactor are as follows: pressure of 3MPa~30MPa and temperature of 220~400℃. The crude methanol obtained after gas-liquid separation and purification in a distillation column contains 99-99.99% methanol by mass. The hydrogen-rich gas with an H2 concentration of 85%~95% after gas-liquid separation is reused and mixed with fresh hydrogen in the hydrogen-rich gas mixer (16). The volume percentage of hydrogen in the mixed gas is 90%~99%, and it enters the carbonate hydrogenation reactor through the hydrogen inlet.

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