A zero-carbon power generation and green methanol synthesis system and method coupled with SOEC

Abstract

This invention discloses a zero-carbon power generation and green methanol synthesis system and method coupled with SOEC (Solar-Energy Integrated Circuit), belonging to the field of synergistic coupling technology of new energy and thermal power generation. The system includes fluctuating green electricity from a large-scale wind and solar new energy base, a supercritical steam-water thermal system of a thermal power plant, an oxygen-enriched combustion boiler in a coal-fired power plant, a CO2 condensation, purification, and capture unit, a high-temperature gas-steam regenerative heat exchanger, SOEC, a medium-temperature high-pressure oxygen buffer tank, a magnesium-based solid hydrogen storage device, a liquid CO2 buffer storage tank, a continuous green methanol synthesis tower, and a liquid methanol finished product storage and transportation tank. This invention can reduce the raw material cost of green methanol; it has relatively high combustion efficiency and can reduce the combustibles in boiler fly ash; it enables coal-fired power assets to become the thermal foundation supporting efficient hydrogen production technology, achieving integrated solar and thermal synergy, with better resource utilization and stability.

Description

Technical Field

[0001] This invention belongs to the field of synergistic coupling technology of new energy and thermal power generation, specifically involving a zero-carbon power generation and green methanol synthesis system and method coupled with SOEC. Background Technology

[0002] Currently, under the development model of large-scale new energy bases that bundle wind, solar, and thermal power for transmission, absorbing curtailed wind and solar power and achieving deep decarbonization of coal-fired power systems have become important development directions in this field. Utilizing renewable energy electricity to electrolyze water to produce green hydrogen, and combining this with carbon capture technology in thermal power plants to synthesize green methanol, can simultaneously achieve efficient absorption of new energy, low-carbon operation of coal-fired units, and large-scale production of green fuels. This is the mainstream technological route for multi-energy complementarity and zero-carbon energy systems.

[0003] Current water electrolysis for hydrogen production mainly uses alkaline electrolyzers (ALK) or proton exchange membrane electrolyzers (PEM), which have a significant upper limit on energy conversion efficiency, typically only around 60%. The high energy consumption (65%) in hydrogen production leads to high costs for green methanol feedstock. Solid oxide electrolysis cells (SOECs), as a highly efficient high-temperature electrolysis technology, can increase hydrogen production efficiency to over 80%~90%, exhibiting significant energy efficiency advantages. However, this technology requires a continuous consumption of a large amount of 700℃~800℃ high-temperature heat source to generate superheated steam. In pure green electricity ionization grid operation scenarios, using electric heating to generate high-temperature steam will consume a significant amount of green electricity, significantly offsetting the high efficiency advantage of SOECs, becoming a core bottleneck restricting its engineering application.

[0004] Meanwhile, existing coal-fired power plant oxy-fuel combustion carbon capture systems typically require independent air separation, compression, and heating units, resulting in high energy consumption for oxygen production, high carbon capture costs, and low system integration. Furthermore, the large amounts of high-temperature and medium-temperature waste heat from coal-fired power plants are not being utilized efficiently in a cascade manner, and there is a lack of effective buffering mechanisms for the unstable hydrogen production load caused by fluctuations in green electricity. In summary, currently, in zero-carbon power generation and fuel preparation systems, the cost of high-temperature heat source supply from SOEC is relatively high, coal-fired power plants and SOEC systems struggle to achieve synergy between high-temperature heat sources and high-temperature oxygen, resulting in insufficient cascade utilization of thermal energy, high costs for oxy-fuel combustion carbon capture, and the need for further improvement in system stability. Summary of the Invention

[0005] This invention provides a zero-carbon power generation and green methanol synthesis system and method coupled with SOEC, aiming to solve the problems in current zero-carbon power generation and fuel preparation systems, such as the high cost of SOEC high-temperature heat source supply, the difficulty in achieving synergy between high-temperature heat source and high-temperature oxygen in thermal power plants and SOEC systems, insufficient utilization of thermal energy in stages, high cost of carbon capture in oxygen-enriched combustion, and the need for further improvement in system stability.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a zero-carbon power generation and green methanol synthesis system coupled with SOEC, comprising: fluctuating green power from a large-scale wind and solar new energy base, a supercritical steam-water thermal system from a thermal power plant, an oxygen-enriched combustion boiler for coal-fired power, a CO2 condensation, purification, and capture unit, a high-temperature gas-steam regenerative heat exchanger, SOEC, a medium-temperature high-pressure oxygen buffer tank, a magnesium-based solid hydrogen storage device, a liquid CO2 buffer storage tank, a continuous green methanol synthesis tower, and a liquid methanol finished product storage and transportation tank; wherein: The power output of the fluctuating green electricity in the wind and solar new energy base is connected to the power input of SOEC; the steam output of the supercritical steam-water thermal system of the thermal power plant is connected to the steam input of SOEC via a high-temperature gas-steam regenerative heat exchanger. The high-temperature product output end of SOEC is connected to the high-temperature product gas input end of the high-temperature gas-steam regenerative heat exchanger, the hydrogen output end after heat exchange is connected to the magnesium-based solid hydrogen storage device, and the oxygen output end after heat exchange is connected to the combustion aid input end of the coal-fired oxygen-enriched combustion boiler via the medium-temperature high-pressure oxygen buffer tank. The flue gas output of the coal-fired oxygen-enriched combustion boiler is connected to the carbon source input of the green methanol continuous synthesis tower via a CO2 condensation, purification and capture unit and a liquid CO2 buffer storage tank; the hydrogen output of the magnesium-based solid hydrogen storage device is connected to the hydrogen source input of the green methanol continuous synthesis tower. The exothermic output ends of both the magnesium-based solid hydrogen storage device and the green methanol continuous synthesis tower are connected to the supercritical steam-water thermal system of the thermal power plant and the feedwater preheating input end of SOEC; the methanol output end of the green methanol continuous synthesis tower is connected to the liquid methanol finished product storage and transportation tank.

[0007] In some implementations, the steam temperature output from the supercritical steam-water thermal system of the thermal power plant is 550°C-600°C, and the high-temperature gas-steam regenerative heat exchanger heats the steam to a preset temperature before sending it into the SOEC.

[0008] In some implementations, the high-temperature hydrogen and pure oxygen output terminals of the SOEC are connected to the high-temperature product gas input terminal of a high-temperature gas-steam regenerative heat exchanger; the SOEC operates at thermal neutral voltage or micro-overpotential, utilizing the Joule heating of electrochemical polarization within the stack to achieve steam temperature rise.

[0009] In some embodiments, the magnesium-based solid hydrogen storage device is used to store hydrogen and supply it to the green methanol continuous synthesis tower for dehydrogenation; the hydrogen output end of the magnesium-based solid hydrogen storage device is connected to the hydrogen input end of the green methanol continuous synthesis tower.

[0010] In some embodiments, the exothermic temperature of the methanol synthesis reaction in the green methanol continuous synthesis tower is 250°C-300°C; the crude methanol produced by the green methanol continuous synthesis tower is transported to a liquid methanol finished product storage tank for storage as liquid methanol finished product.

[0011] In some embodiments, the oxygen output end of the medium-temperature high-pressure oxygen buffer tank is connected to the combustion aid input end of the coal-fired oxy-fuel boiler. The medium-temperature high-pressure oxygen buffer tank is used to supply oxygen to the coal-fired oxy-fuel boiler, and the oxygen-enriched flue gas output end of the coal-fired oxy-fuel boiler can output oxygen-enriched flue gas with a CO2 concentration of not less than 80%.

[0012] Furthermore, the oxygen-enriched flue gas output end of the coal-fired oxygen-enriched combustion boiler is connected to the flue gas input end of the CO2 condensation, purification and capture unit. The CO2 condensation, purification and capture unit separates, purifies and liquefies the oxygen-enriched flue gas to obtain liquid CO2 and transports it to the liquid CO2 buffer storage tank.

[0013] In some implementations, the heat released from hydrogen absorption by the magnesium-based solid hydrogen storage device and the heat released from synthesis by the green methanol continuous synthesis tower are all used to preheat the boiler feedwater of the supercritical steam-water thermal system of the thermal power plant and the ambient temperature water of SOEC.

[0014] In some implementations, the hydrogen production efficiency of SOEC is controlled to be no less than 80%.

[0015] This invention also provides a zero-carbon power generation and green methanol synthesis method coupled with SOEC, which is based on the above-mentioned zero-carbon power generation and green methanol synthesis system coupled with SOEC, and includes the following steps: S1, the large-scale wind and solar new energy base supplies green electricity to SOEC for electrolysis. The supercritical steam-water thermal system of the thermal power plant sends high-temperature and high-pressure steam into the high-temperature gas-steam regenerative heat exchanger for heat exchange and then delivers it to SOEC. S2 and SOEC electrolysis produce high-temperature hydrogen and high-temperature oxygen, which are sent to a high-temperature gas-steam regenerative heat exchanger for heat exchange. After heat exchange, the hydrogen is passed into a magnesium-based solid hydrogen storage device, and the oxygen is sent to a coal-fired oxygen-enriched combustion boiler as a combustion aid through a medium-temperature high-pressure oxygen buffer tank. S3. The oxygen-enriched flue gas produced by the coal-fired oxygen-enriched combustion boiler is purified and liquefied by the CO2 condensation, purification and capture unit to obtain liquid CO2, which is then stored in the liquid CO2 buffer tank and transported to the green methanol continuous synthesis tower. S4, the magnesium-based solid hydrogen storage unit supplies hydrogen to the green methanol continuous synthesis tower. The hydrogen reacts with CO2 to produce methanol, which is then transported to the liquid methanol finished product storage tank for storage. S5, the hydrogen absorption and heat release of the magnesium-based solid hydrogen storage device, and the synthesis and heat release of the green methanol continuous synthesis tower, respectively preheat the boiler feedwater of the supercritical steam-water thermal system of the thermal power plant and the ambient temperature water of SOEC.

[0016] Compared with existing technologies, the zero-carbon power generation and green methanol synthesis system and method coupled with SOEC of the present invention have the following beneficial effects: This invention presents a zero-carbon power generation and green methanol synthesis system coupled with SOEC (Solar-Energy-Energy Coal). It transfers the most energy-intensive water vaporization and superheating processes of SOEC to the inexpensive industrial-grade heat source of the thermal power plant, allowing green electricity to be used solely for breaking the chemical bonds of water molecules. Compared to ALK (Alternating Current-Based Hydrogen) hydrogen production, the power consumption per kilogram of hydrogen can be reduced by 25% to 30%, significantly lowering the raw material cost (LCOE) of green methanol. This invention directly introduces high-temperature pure oxygen at a preset temperature, which, in actual operating conditions, not only drastically reduces carbon capture costs from, for example, 300 yuan to below 90 yuan / ton of CO2, but also allows for rapid ignition of pulverized coal in the furnace, resulting in relatively high combustion efficiency and reducing combustible fly ash from the boiler. This invention enables coal-fired power assets to move beyond being merely a backup for green electricity, achieving integrated solar-thermal synergy and possessing certain engineering applicability. Attached Figure Description

[0017] The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0018] Figure 1 This is a schematic diagram of the architecture of a zero-carbon power generation and green methanol synthesis system coupled with SOEC according to the present invention.

[0019] Among them, 100 is the fluctuating green electricity of the wind and solar new energy base, 200 is the supercritical steam-water thermal system of the thermal power plant, 500 is the green methanol continuous synthesis tower, and 600 is the liquid methanol finished product storage and transportation tank. 201. Oxygen-fired boiler; 202. CO2 condensation, purification and capture unit; 301. High-temperature gas-steam regenerative heat exchanger; 302. SOEC; 401. Medium-temperature high-pressure oxygen buffer tank; 402. Magnesium-based solid hydrogen storage device; 403. Liquid CO2 buffer storage tank. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0022] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0023] It should be noted that the apparatus and methods disclosed in the embodiments herein can also be implemented in other ways. The apparatus embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings show the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments herein. In this regard, each block in a flowchart or block diagram may represent a module, program, or part of code containing one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system to perform the specified function or action, or can be implemented using a combination of dedicated hardware and computer instructions.

[0024] In addition, the functional modules in the various embodiments of this article can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0025] like Figure 1As shown, this invention provides a zero-carbon power generation and green methanol synthesis system coupled with SOEC, including a large-scale wind and solar new energy base fluctuating green power 100, a supercritical steam-water thermal system of a thermal power plant 200, a coal-fired oxygen-enriched combustion boiler 201, a CO2 condensation, purification, and capture unit 202, a high-temperature gas-steam regenerative heat exchanger 301, SOEC 302, a medium-temperature high-pressure oxygen buffer tank 401, a magnesium-based solid hydrogen storage device 402, a liquid CO2 buffer storage tank 403, a green methanol continuous synthesis tower 500, and a liquid methanol finished product storage and transportation tank 600; wherein: The power output terminal of the large-scale wind and solar new energy base's fluctuating green electricity 100 is connected to the power input terminal of SOEC302; the steam output terminal of the thermal power plant's supercritical steam-water thermal system 200 is connected to the steam input terminal of SOEC302 via a high-temperature gas-steam regenerative heat exchanger 301. The high-temperature product output end of SOEC302 is connected to the high-temperature product gas input end of the high-temperature gas-steam regenerative heat exchanger 301. The hydrogen output end after heat exchange is connected to the magnesium-based solid hydrogen storage device 402. The oxygen output end after heat exchange is connected to the combustion aid input end of the coal-fired oxygen-enriched combustion boiler 201 via the medium-temperature high-pressure oxygen buffer tank 401. The flue gas output end of the coal-fired oxygen-enriched combustion boiler 201 is connected to the carbon source input end of the green methanol continuous synthesis tower 500 via the CO2 condensation purification and capture unit 202 and the liquid CO2 buffer storage tank 403; the hydrogen output end of the magnesium-based solid hydrogen storage device 402 is connected to the hydrogen source input end of the green methanol continuous synthesis tower 500. The exothermic output ends of the magnesium-based solid hydrogen storage device 402 and the green methanol continuous synthesis tower 500 are both connected to the feedwater preheating input end of the supercritical steam-water thermal system 200 and SOEC302 of the thermal power plant; the methanol output end of the green methanol continuous synthesis tower 500 is connected to the liquid methanol finished product storage and transportation tank 600.

[0026] This invention discloses a zero-carbon power generation and green methanol synthesis system coupled with SOEC (Supercritical Steam-Water Thermal System). The supercritical steam-water thermal system 200 of a thermal power plant serves as a stable high-temperature heat source, directly providing the required steam to SOEC302. This eliminates the need for a separate electric heating steam generator, reducing the cost of the high-grade heat source required for SOEC302 operation. Simultaneously, the high-temperature oxygen generated by SOEC302 is directly recycled to the oxygen-enriched combustion boiler 201 of the coal-fired power plant, improving the thermodynamic matching and overall energy utilization efficiency of the entire system. The magnesium-based solid-state hydrogen storage device 402 effectively mitigates load fluctuations caused by fluctuating green electricity from large-scale wind and solar power bases, ensuring continuous and stable operation of the hydrogen production and methanol synthesis processes. The system will... The exothermic heat generated by the magnesium-based solid hydrogen storage device 402 and the green methanol continuous synthesis tower 500 is recovered and used to preheat the feed water of the supercritical steam-water thermal system 200 and SOEC302 in the thermal power plant, realizing the internal recycling of waste heat and reducing the overall energy consumption of the system. The coal-fired oxy-fuel combustion boiler 201, together with the CO2 condensation, purification and capture unit 202, can achieve efficient enrichment and recovery of carbon dioxide in the flue gas, providing a stable and low-cost carbon source for the green methanol continuous synthesis tower 500. This enables the system to achieve zero-carbon power generation while completing the large-scale production of green methanol, realizing the efficient consumption of new energy, low-carbon operation of coal-fired units and green fuel production, and improving the stability of system operation and the effect of low carbon and environmental protection.

[0027] In some operating conditions, this invention provides a zero-carbon power generation and green methanol synthesis system coupled with SOEC. The steam temperature output from the supercritical steam-water thermal system 200 of the thermal power plant is 550℃-600℃. The high-temperature gas-steam regenerative heat exchanger 301 raises the steam temperature to a preset temperature before sending it into SOEC 302. By setting the temperature range of the steam output from the supercritical steam-water thermal system 200 of the thermal power plant and the steam temperature raising function of the high-temperature gas-steam regenerative heat exchanger 301, this invention ensures that the steam sent into SOEC 302 meets the temperature conditions required for high-temperature electrolysis, leveraging the high-efficiency hydrogen production advantage of SOEC 302. Through the cascade heat exchange between the thermal power plant's own high-temperature steam and the high-temperature gas-steam regenerative heat exchanger 301, the steam temperature is increased, avoiding energy loss from additional electric heating and enhancing the system's thermal energy utilization efficiency. The high-temperature hydrogen and pure oxygen output terminals of the SOEC302 of this invention are connected to the high-temperature product gas input terminal of the high-temperature gas-steam regenerative heat exchanger 301. The SOEC302 operates under thermal neutral voltage or micro-overpotential and utilizes the Joule heat of electrochemical polarization inside the fuel cell stack to achieve the temperature rise of the steam. This allows the SOEC302 to complete the final temperature rise of the steam without the need for external high-temperature heating equipment, reducing equipment investment and operating energy consumption, and making the high-temperature electrolysis process more efficient and energy-saving.

[0028] Furthermore, this invention provides a zero-carbon power generation and green methanol synthesis system coupled with SOEC. A magnesium-based solid-state hydrogen storage device 402 stores hydrogen and supplies it to the green methanol continuous synthesis tower 500 for dehydrogenation. The hydrogen output of the magnesium-based solid-state hydrogen storage device 402 is connected to the hydrogen input of the green methanol continuous synthesis tower 500. This system can store excess hydrogen when green electricity is abundant and output hydrogen steadily when green electricity is insufficient, effectively mitigating the fluctuations in wind and solar power generation, ensuring a stable feedstock supply to the green methanol continuous synthesis tower 500, and improving the overall system's operational continuity and load regulation capabilities. The exothermic temperature of the methanol synthesis reaction in the green methanol continuous synthesis tower 500 is 250℃-300℃. The crude methanol produced by the green methanol continuous synthesis tower 500 is transported to a liquid methanol finished product storage tank 600 for storage as liquid methanol finished product, thereby ensuring that the methanol synthesis reaction proceeds efficiently at a suitable temperature. Simultaneously, it achieves stable collection and storage of crude methanol, ensuring the continuous and reliable production of green methanol products via the liquid methanol finished product storage tank 600, and improving the stability of product transportation and storage.

[0029] The oxygen output end of the medium-temperature high-pressure oxygen buffer tank 401 of this invention is connected to the combustion aid input end of the coal-fired oxy-fuel combustion boiler 201. The medium-temperature high-pressure oxygen buffer tank 401 is used to supply oxygen to the coal-fired oxy-fuel combustion boiler 201, and the oxygen-enriched flue gas output end of the coal-fired oxy-fuel combustion boiler 201 can output oxygen-enriched flue gas with a CO2 concentration exceeding 80%. This invention can significantly improve combustion efficiency and reduce the difficulty of subsequent carbon capture, laying the foundation for obtaining high-purity carbon sources. Furthermore, the oxygen-enriched flue gas output end of the coal-fired oxy-fuel combustion boiler 201 is connected to the flue gas input end of the CO2 condensation, purification, and capture unit 202. The CO2 condensation, purification, and capture unit 202 separates, purifies, and liquefies the oxygen-enriched flue gas to obtain liquid CO2, which is then transported to the liquid CO2 buffer storage tank 403. The oxygen-rich flue gas is separated, purified, and liquefied by the CO2 condensation, purification, and capture unit 202, and the liquid CO2 is transported to the liquid CO2 buffer storage tank 403. This achieves efficient recovery and stable storage of carbon resources in the flue gas, continuously providing a high-purity carbon source for the green methanol continuous synthesis tower 500, improving the level of carbon resource utilization, and reducing the energy consumption for capture and transportation.

[0030] This invention discloses a zero-carbon power generation and green methanol synthesis system coupled with SOEC (Solar-Electro-Mechanical Combined Heat and Power). The heat released from hydrogen absorption in the magnesium-based solid-state hydrogen storage device 402 and the heat released from synthesis in the green methanol continuous synthesis tower 500 are all used to preheat the boiler feedwater of the supercritical steam-water thermal system 200 of a thermal power plant and the ambient temperature water of SOEC302. This invention achieves cascaded recovery and utilization of warm and waste heat in the system, reducing system heat loss and lowering the preheating energy consumption of the thermal power plant and SOEC302 unit, resulting in more efficient energy utilization and a more complete thermodynamic closed loop for the entire system. Furthermore, the hydrogen production efficiency of SOEC302 is controlled to be no less than 80%, ensuring that the system maintains a high level of hydrogen production. Compared with traditional electrolytic hydrogen production technology, it reduces the unit hydrogen power consumption, giving the system the advantages of low energy consumption and low-cost operation.

[0031] This invention also provides a zero-carbon power generation and green methanol synthesis method coupled with SOEC, comprising the following steps: S1, the large-scale wind and solar new energy base fluctuates green electricity 100 to supply electrolysis electricity to SOEC302. The supercritical steam-water thermal system 200 of the thermal power plant sends high-temperature and high-pressure steam into the high-temperature gas-steam regenerative heat exchanger 301 for heat exchange and then delivers it to SOEC302. S2 and SOEC302 electrolysis produces high-temperature hydrogen and high-temperature oxygen, which are sent to high-temperature gas-steam regenerative heat exchanger 301 for heat exchange. After heat exchange, the hydrogen is passed into magnesium-based solid hydrogen storage device 402, and the oxygen after heat exchange is sent to coal-fired oxygen-enriched combustion boiler 201 via medium-temperature high-pressure oxygen buffer tank 401 as a combustion aid. S3. The oxygen-enriched flue gas produced by the coal-fired oxygen-enriched combustion boiler 201 is purified and liquefied by the CO2 condensation, purification and capture unit 202 to obtain liquid CO2, which is then stored in the liquid CO2 buffer storage tank 403 and transported to the green methanol continuous synthesis tower 500. S4. Magnesium-based solid hydrogen storage device 402 supplies hydrogen to green methanol continuous synthesis tower 500. Hydrogen reacts with CO2 to produce methanol, which is then transported to liquid methanol finished product storage tank 600 for storage. S5, the hydrogen absorption and heat release of the magnesium-based solid hydrogen storage device 402, and the synthesis and heat release of the green methanol continuous synthesis tower 500, respectively preheat the boiler feedwater of the supercritical steam-water thermal system 200 of the thermal power plant and the room temperature water of SOEC302.

[0032] In some embodiments, the present invention provides a zero-carbon power generation and green methanol synthesis system coupled with SOEC, which thermodynamically matches the high-temperature hydrogen production characteristics of SOEC, the steam-water thermal cycle of thermal power plants, oxygen-enriched combustion technology, and magnesium-based solid hydrogen storage.

[0033] This invention extracts high-temperature, high-pressure steam (500℃-600℃) from the steam-water system of a thermal power plant and sends it to the hydrogen production island. The inexpensive heat source of the thermal power plant handles the most energy-consuming stage of the water vaporization process (liquid water temperature rise and latent heat of vaporization), providing over 80% of the heat for steam generation. The high-purity hydrogen and oxygen produced by SOEC electrolysis have an initial outlet temperature as high as 750℃~800℃.

[0034] This invention discloses a zero-carbon power generation and green methanol synthesis system coupled with a steam-gas regenerative heat exchanger (301). A high-temperature gas-steam regenerative heat exchanger is installed at the front end of the SOEC. Steam at 600°C from a thermal power plant is introduced into this heat exchanger, where it undergoes countercurrent heat exchange with the 800°C high-temperature hydrogen / oxygen gas discharged from the SOEC, further superheating it to 700°C~750°C. Simultaneously, the discharged oxygen is moderately cooled to approximately 600°C, precisely meeting the optimal delivery and injection temperature for combustion in an oxygen-enriched boiler. During peak green electricity generation, the SOEC is controlled to operate at high load under thermal neutral voltage or slight overpotential, utilizing the electrochemical polarization Joule heat (exothermic effect) generated within the fuel cell stack to complete the final 50°C~100°C temperature rise within the stack. This reduces the need for external high-temperature electric heaters to a certain extent, achieving a closed-loop thermodynamic system.

[0035] Furthermore, in the high-temperature water electrolysis process of the SOEC of this invention, the by-product oxygen is cooled to 600°C via a high-temperature gas-steam regenerative heat exchanger 301 and directly introduced into the boiler of a thermal power plant as a combustion aid for oxygen-enriched combustion. This not only eliminates nitrogen interference and increases the carbon capture concentration to over 80%, but also directly injects a large amount of high-grade sensible heat carried by the oxygen into the boiler, improving the thermal efficiency of the thermal power plant. The high-purity hydrogen produced by the SOEC driven by the wide-power-fluctuation green electricity of this invention is pressurized into a magnesium-based solid hydrogen storage device (MgH2) for excess. The heat released by the magnesium-based alloy during hydrogen absorption (300-400°C) and the heat released from the downstream methanol synthesis tower (250-300°C) are collected and used to preheat the boiler feedwater of the thermal power plant or preheat the ambient-temperature water entering the SOEC. This achieves the cascade utilization of heat within the system.

[0036] In summary, this invention presents a zero-carbon power generation and green methanol synthesis system coupled with an SOEC (Solar Energy Storage and Electrolysis) system. Unlike conventional unidirectional systems, this system utilizes a two-way forced coupling network by supplying steam / heat (above 600°C) to the SOEC from a thermal power plant and supplying high-temperature pure oxygen from the SOEC to the thermal power boiler. This invention eliminates the need for devices that cryogenically / compress or ambient-temperature-controlled the byproduct oxygen from electrolysis, directly utilizing the high-temperature sensible heat from the SOEC outlet to enhance the furnace temperature and combustion efficiency of oxygen-enriched coal combustion. This invention constructs a top-down thermodynamic closed loop, with the high-temperature section (>600°C) of the thermal power plant serving the SOEC; and the mid-temperature section (350°C) of magnesium-based hydrogen storage and the methanol exothermic zone (250°C) serving the thermal power boiler feedwater. This improves the isolated waste heat of each subsystem, controls costs, and enhances the system's resource utilization and stability.

[0037] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Anyone skilled in the art can readily implement the present invention according to the description and above. Any modifications, alterations, or equivalent variations made using the technical content disclosed above are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A zero-carbon power generation and green methanol synthesis system coupled with SOEC, characterized in that, This includes a large-scale wind and solar new energy base with fluctuating green electricity (100), a supercritical steam-water thermal system for a thermal power plant (200), an oxygen-enriched combustion boiler for coal-fired power plants (201), a CO2 condensation, purification, and capture unit (202), a high-temperature gas-steam regenerative heat exchanger (301), an SOEC (302), a medium-temperature high-pressure oxygen buffer tank (401), a magnesium-based solid hydrogen storage device (402), a liquid CO2 buffer storage tank (403), a green methanol continuous synthesis tower (500), and a liquid methanol finished product storage and transportation tank (600); among which: The power output terminal of the large-scale wind and solar energy base fluctuating green electricity (100) is connected to the power input terminal of SOEC (302); the steam output terminal of the supercritical steam-water thermal system (200) of the thermal power plant is connected to the steam input terminal of SOEC (302) via a high-temperature gas-steam regenerative heat exchanger (301). The high-temperature product output end of the SOEC (302) is connected to the high-temperature product gas input end of the high-temperature gas-steam regenerative heat exchanger (301), the hydrogen output end after heat exchange is connected to the magnesium-based solid hydrogen storage device (402), and the oxygen output end after heat exchange is connected to the combustion aid input end of the coal-fired oxygen-enriched combustion boiler (201) via the medium-temperature high-pressure oxygen buffer tank (401). The flue gas output end of the coal-fired oxygen-enriched combustion boiler (201) is connected to the carbon source input end of the green methanol continuous synthesis tower (500) via the CO2 condensation purification and capture unit (202) and the liquid CO2 buffer storage tank (403); the hydrogen output end of the magnesium-based solid hydrogen storage device (402) is connected to the hydrogen source input end of the green methanol continuous synthesis tower (500). The exothermic output ends of the magnesium-based solid hydrogen storage device (402) and the green methanol continuous synthesis tower (500) are both connected to the feedwater preheating input end of the supercritical steam-water thermal system (200) and SOEC (302) of the thermal power plant; the methanol output end of the green methanol continuous synthesis tower (500) is connected to the liquid methanol finished product storage and transportation tank (600).

2. The zero-carbon power generation and green methanol synthesis system coupled with SOEC according to claim 1, characterized in that, The steam temperature output by the supercritical steam-water thermal system (200) of the thermal power plant is 550℃-600℃. The high-temperature gas-steam regenerative heat exchanger (301) heats the steam to the preset temperature and then sends it into SOEC (302).

3. The zero-carbon power generation and green methanol synthesis system coupled with SOEC according to claim 1, characterized in that, The high-temperature hydrogen and pure oxygen output terminals of the SOEC (302) are connected to the high-temperature product gas input terminal of the high-temperature gas-vapor regenerative heat exchanger (301); the SOEC (302) operates under thermal neutral voltage or micro-overpotential and utilizes the electrochemical polarization Joule heat inside the stack to achieve the temperature rise of the steam.

4. The zero-carbon power generation and green methanol synthesis system coupled with SOEC according to claim 1, characterized in that, The magnesium-based solid hydrogen storage device (402) is used to store hydrogen and supply it to the green methanol continuous synthesis tower (500) for dehydrogenation; the hydrogen output end of the magnesium-based solid hydrogen storage device (402) is connected to the hydrogen input end of the green methanol continuous synthesis tower (500).

5. The zero-carbon power generation and green methanol synthesis system coupled with SOEC according to claim 1, characterized in that, The exothermic temperature of the methanol synthesis reaction in the green methanol continuous synthesis tower (500) is 250℃-300℃; the crude methanol produced by the green methanol continuous synthesis tower (500) is transported to the liquid methanol finished product storage tank (600) for storage as liquid methanol finished product.

6. The zero-carbon power generation and green methanol synthesis system coupled with SOEC according to claim 1, characterized in that, The oxygen output end of the medium-temperature high-pressure oxygen buffer tank (401) is connected to the combustion aid input end of the coal-fired oxy-fuel combustion boiler (201). The medium-temperature high-pressure oxygen buffer tank (401) is used to supply oxygen to the coal-fired oxy-fuel combustion boiler (201). The oxygen-enriched flue gas output end of the coal-fired oxy-fuel combustion boiler (201) can output oxygen-enriched flue gas with a CO2 concentration of not less than 80%.

7. The zero-carbon power generation and green methanol synthesis system coupled with SOEC according to claim 6, characterized in that, The oxygen-enriched flue gas output end of the coal-fired oxygen-enriched combustion boiler (201) is connected to the flue gas input end of the CO2 condensation, purification and collection unit (202). The CO2 condensation, purification and collection unit (202) separates, purifies and liquefies the oxygen-enriched flue gas to obtain liquid CO2 and transports it to the liquid CO2 buffer storage tank (403).

8. The zero-carbon power generation and green methanol synthesis system coupled with SOEC according to claim 1, characterized in that, The heat released from hydrogen absorption by the magnesium-based solid hydrogen storage device (402) and the heat released from synthesis by the green methanol continuous synthesis tower (500) are all used to preheat the boiler feedwater of the supercritical steam-water thermal system (200) of the thermal power plant and the ambient temperature water of SOEC (302).

9. The zero-carbon power generation and green methanol synthesis system coupled with SOEC according to claim 1, characterized in that, The hydrogen production efficiency of the SOEC (302) is controlled to be no less than 80%.

10. A method for zero-carbon power generation and green methanol synthesis coupled with SOEC, characterized in that, It is based on the zero-carbon power generation and green methanol synthesis system coupled with SOEC as described in any one of claims 1-9, and includes the following steps: S1, the fluctuating green electricity (100) of the wind and solar new energy base supplies electrolysis electricity to SOEC (302). The supercritical steam-water thermal system (200) of the thermal power plant sends high-temperature and high-pressure steam into the high-temperature gas-steam regenerative heat exchanger (301) for heat exchange, and then delivers it to SOEC (302). S2 and SOEC (302) electrolyze to produce high-temperature hydrogen and high-temperature oxygen, which are sent to the high-temperature gas-steam regenerative heat exchanger (301) for heat exchange. After heat exchange, the hydrogen is passed into the magnesium-based solid hydrogen storage device (402), and the oxygen after heat exchange is sent to the coal-fired oxygen-enriched combustion boiler (201) via the medium-temperature high-pressure oxygen buffer tank (401) as a combustion aid. S3. The oxygen-enriched flue gas generated by the coal-fired oxygen-enriched combustion boiler (201) is purified and liquefied by the CO2 condensation purification and collection unit (202) to obtain liquid CO2, which is then stored in the liquid CO2 buffer tank (403) and transported to the green methanol continuous synthesis tower (500). S4, the magnesium-based solid hydrogen storage device (402) supplies hydrogen to the green methanol continuous synthesis tower (500). The hydrogen reacts with CO2 to produce methanol, which is then transported to the liquid methanol finished product storage tank (600) for storage. S5, the hydrogen absorption and heat release of the magnesium-based solid hydrogen storage device (402) and the synthesis heat release of the green methanol continuous synthesis tower (500) preheat the boiler feedwater of the supercritical steam-water thermal system (200) of the thermal power plant and the ambient temperature water of SOEC (302), respectively.

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