Solar-driven methanol synthesis and water electrolysis coupling system

Abstract

The invention belongs to the technical field of solar comprehensive utilization and methanol synthesis, and relates to a solar-driven methanol synthesis and water electrolysis coupling system. The device comprises a solar energy light-electricity-heat coupling unit, the solar energy light-electricity-heat coupling unit is composed of a water tank, a preheater, a parabolic trough type solar heat collector, a photovoltaic cell panel and a heat exchanger, a water outlet of the water tank is connected with a water inlet of the preheater through a pipeline, a water outlet of the preheater is connected with a water inlet of the parabolic trough type solar heat collector through a pipeline, and a water outlet of the photovoltaic cell panel is connected with a water outlet of the parabolic trough type solar heat collector through a pipeline; a water outlet of the parabolic trough type solar heat collector is connected with a heat flow inlet of the heat exchanger through a pipeline, and the photovoltaic cell panel is electrically connected with the electric heater and system electric equipment through cables. According to the invention, through a solar light-electricity-heat multi-energy coupling technology, the utilization limitation of single photo-thermal or photo-electricity is broken through, high-temperature heat energy is supplied through photo-thermal, electric energy is supplemented through photo-electricity, a solid oxide electrolytic cell (SOEC) is cooperatively driven to produce hydrogen, and the solar energy potential is excavated to the maximum extent.

Description

Technical Field

[0001] This invention belongs to the field of solar energy comprehensive utilization and methanol synthesis technology, and relates to a solar-driven methanol synthesis and water electrolysis coupling system. Background Technology

[0002] Methanol is an important chemical raw material and clean energy carrier, widely used in chemical production (such as synthesis processes in chemical plants) and fuel substitution (such as energy supply for steel plants). Currently, traditional methanol synthesis mainly relies on fossil fuels (such as coal and natural gas) through gasification and synthesis processes. This not only results in high carbon emissions and energy consumption but also fails to effectively utilize the carbon resources in flue gas from chemical and steel plants, leading to the dual drawbacks of carbon emissions and raw material waste. In response to the demand for low-carbon development, the technology of producing methanol using renewable energy coupled with carbon capture in factories has received considerable attention in recent years. Furthermore, combining hydrogen production through water electrolysis with the synthesis of methanol from captured factory flue gas (CO, CO2) is also a potential pathway that aligns with the carbon cycle in the chemical and steel industries.

[0003] Solar energy, as a clean and abundant renewable energy source, has seen its photovoltaic and solar thermal utilization forms gradually mature. However, existing solar-driven methanol synthesis and water electrolysis systems suffer from problems such as low integration and insufficient energy synergy. For example, photovoltaic power and solar thermal energy are not efficiently coupled into the same system, and the SOEC (solid oxide electrolyzer) and methanol synthesis reactor have poor compatibility, resulting in limited energy conversion efficiency. This makes it difficult to achieve efficient utilization of flue gas carbon resources and low-cost, low-emission large-scale methanol production in chemical plants, steel mills, and other similar settings. Therefore, there is an urgent need to design a solar-driven methanol synthesis and water electrolysis coupling system that can overcome these shortcomings.

[0004] To overcome the shortcomings of existing technologies, people have continuously explored and proposed various solutions. For example, Chinese patent discloses a methanol synthesis tower device [application number: 201410373041.5], which includes: a synthesis tower body, with upper and lower tube sheets respectively installed at the upper and lower ends of the synthesis tower body, the synthesis tower body being welded and fixed to the upper and lower tube sheets respectively, an upper tube box being welded and fixed to the top of the upper tube sheet, and a lower tube box being welded and fixed to the bottom of the lower tube sheet, a number of heat exchange tubes being installed inside the synthesis tower body, the upper and lower ends of the heat exchange tubes being respectively inserted into and welded to the tube holes on the upper and lower tube sheets, the upper tube opening of the heat exchange tubes being connected to the upper tube box, and the lower tube opening of the heat exchange tubes being connected to the lower tube box, a manhole with an openable and closable cover being opened on the synthesis tower body near the upper tube sheet, and a process partition being installed inside the lower tube box, with through holes opened on the process partition. However, this solution is difficult to achieve efficient utilization of flue gas carbon resources and low-cost, low-emission large-scale methanol production in chemical plants, steel plants and other scenarios. It also suffers from low integration, insufficient energy synergy and low energy conversion efficiency during use. Summary of the Invention

[0005] The purpose of this invention is to address the above-mentioned problems by providing a solar-driven methanol synthesis and water electrolysis coupling system that breaks through the energy efficiency bottleneck of traditional systems through solar photovoltaic-electrical-thermal multi-energy coupling, membrane reaction enhancement, and industrial carbon cycle integration, thereby achieving green hydrogen and green carbon synthesis of methanol, assisting in the low-carbon transformation of industrial scenarios, and possessing both environmental and economic synergistic benefits.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions:

[0007] A solar-driven methanol synthesis and water electrolysis coupled system, comprising:

[0008] The solar photovoltaic-electric-thermal coupling unit consists of a water tank, a preheater, a parabolic trough solar collector, photovoltaic panels, and a heat exchanger. The outlet of the water tank is connected to the inlet of the preheater via a pipe, the outlet of the preheater is connected to the inlet of the parabolic trough solar collector via a pipe, the outlet of the parabolic trough solar collector is connected to the heat inlet of the heat exchanger via a pipe, and the photovoltaic panels are electrically connected to the electric heater and other system equipment via cables.

[0009] The SOEC hydrogen production unit consists of an electric heater and a solid oxide electrolyzer. The electric heater is connected to the heat source inlet of the solid oxide electrolyzer through a pipe, and the water inlet of the solid oxide electrolyzer is connected to the water outlet of the heat exchanger or a water tank through a pipe.

[0010] The carbon capture and raw material pretreatment unit consists of a flue gas collection device, a carbon capture device, and a by-product collection device. The flue gas outlet of the flue gas collection device is connected to the inlet of the carbon capture device through a pipeline. The carbon source outlet of the carbon capture device is connected to the methanol synthesis and refining unit through a pipeline. The by-product outlet of the carbon capture device is connected to the inlet of the by-product collection device through a pipeline.

[0011] The methanol synthesis and refining unit consists of a compressor, a water-conducting membrane reactor, and a distillation unit. The inlet of the compressor is connected to the hydrogen outlet of the solid oxide electrolyzer and the carbon source outlet of the carbon capture device via a pipeline. The outlet of the compressor is connected to the feed inlet of the water-conducting membrane reactor via a pipeline. The product outlet of the water-conducting membrane reactor is connected to the inlet of the distillation unit via a pipeline. The unreacted gas outlet of the distillation unit is circulatedly connected to the inlet of the compressor via a pipeline.

[0012] In the aforementioned solar-driven methanol synthesis and water electrolysis coupled system, a catalyst bed and a NaA molecular sieve membrane are arranged inside the water conduction membrane reactor. The NaA molecular sieve membrane is located in the reaction product flow path of the catalyst bed and is used to separate the H2O generated by the reaction in real time.

[0013] In the aforementioned solar-driven methanol synthesis and water electrolysis coupled system, the photothermal output end of the parabolic trough solar collector is connected to the heat source inlet of the solid oxide electrolysis cell and the preheating pipe of the methanol synthesis raw materials through a pipeline, and the electrical output end of the photovoltaic panel is electrically connected to the electric heater and the compressor through a cable.

[0014] In the aforementioned solar-driven methanol synthesis and water electrolysis coupled system, the flue gas collection device includes a flue gas duct and an induced draft fan. One end of the flue gas duct is connected to the flue gas emission end of a chemical plant or steel plant, and the other end is connected to the inlet pipe of a carbon capture device through the induced draft fan.

[0015] In the aforementioned solar-driven methanol synthesis and water electrolysis coupled system, the carbon capture device includes a pretreatment unit, an adsorption unit, and a desorption unit connected in sequence. The inlet of the pretreatment unit is connected to the outlet pipe of the flue gas collection device, the carbon source outlet pipe of the desorption unit is connected to the inlet of the compressor, and the by-product outlet pipes of the pretreatment unit and the adsorption unit are connected to the inlet of the by-product collection device.

[0016] In the aforementioned solar-driven methanol synthesis and water electrolysis coupled system, the by-product collection device includes a gas-liquid separator and a storage tank. The by-product outlet pipe of the carbon capture device is sequentially connected to the gas-liquid separator and the storage tank. The gas discharge port and liquid collection port of the gas-liquid separator are respectively connected to the corresponding inlets of the storage tank.

[0017] In the aforementioned solar-driven methanol synthesis and water electrolysis coupled system, the heat exchanger's heat inlet is connected to the outlet of the parabolic trough solar collector, the heat outlet is connected to the heat source inlet of the solid oxide electrolysis cell and the raw material preheating pipe of the water conduction membrane reactor, the heat exchanger's water inlet is connected to the drain outlet of the water tank or the solid oxide electrolysis cell, and the water outlet is connected to the inlet of the preheater.

[0018] In the aforementioned solar-driven methanol synthesis and water electrolysis coupling system, the inlet water temperature control system of the solid oxide electrolysis cell includes a preheater, a parabolic trough solar collector, and an electric heater. The heat source inlet of the preheater is connected to the heat flow outlet of the heat exchanger, and the heating element of the electric heater is located inside the shell of the solid oxide electrolysis cell to coordinately control the operating temperature of the electrolysis cell.

[0019] In the aforementioned solar-driven methanol synthesis and water electrolysis coupled system, in the methanol synthesis and purification unit, a circulation pump is installed on the unreacted gas outlet pipe of the distillation unit. The outlet of the circulation pump is connected to the inlet of the compressor through a pipe, and is used to circulate unreacted H2, CO, and CO2 to the water conduction membrane reactor.

[0020] In the aforementioned solar-driven methanol synthesis and water electrolysis coupled system, the desorption unit of the carbon capture device employs temperature swing adsorption or pressure swing adsorption technology, and the NaA molecular sieve membrane has a pore size of 0.3-0.4 nm for selectively separating H2O molecules.

[0021] Compared with existing technologies, the advantages of this invention are:

[0022] 1. This invention overcomes the limitations of single-energy utilization of solar energy by using solar photovoltaic-electrical-thermal multi-energy coupling technology. It maximizes the potential of solar energy by supplying high-temperature heat energy through solar thermal energy and supplementing electrical energy through photovoltaic energy.

[0023] 2. The NaA molecular sieve membrane in the water-conducting membrane reactor of the present invention removes the H2O generated in the reaction in real time, breaking the equilibrium limitation of the methanol synthesis reaction, greatly improving the methanol synthesis efficiency and product purity, and reducing the energy consumption of subsequent separation processes.

[0024] 3. The system in this invention can be directly connected to the flue gas emission systems of chemical plants and steel plants, realizing the coupling of industrial flue gas carbon resource (CO, CO2) recovery with methanol production process, and helping the low-carbon transformation of industrial scenarios.

[0025] 4. This invention uses renewable energy-driven SOEC hydrogen production, combined with carbon captured from industrial flue gas as raw material, to synthesize high-purity green methanol. The entire process is free from fossil energy dependence and has a significant emission reduction effect.

[0026] 5. This invention reduces energy and water waste and enhances the synergistic benefits of the system's economy and environmental protection by recovering waste heat from units such as membrane reactors and SOECs through heat exchangers and by recycling water resources.

[0027] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0028] Figure 1 This is a system schematic diagram of the present invention.

[0029] Figure 2 This is a schematic diagram of the water-conducting membrane reactor structure of the present invention.

[0030] In the diagram: 1. Water tank; 2. Preheater; 3. Parabolic trough solar collector; 4. Photovoltaic panel; 5. Heat exchanger; 6. Electric heater; 7. Solid oxide electrolysis cell; 8. Compressor; 9. Water conduction membrane reactor; 10. Flue gas collection device; 11. Carbon capture device; 12. By-product collection device; 13. Distillation device. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings.

[0032] Example 1

[0033] like Figure 1 , Figure 2 As shown, a solar-driven methanol synthesis and water electrolysis coupled system includes:

[0034] In this embodiment, it includes a solar photovoltaic-electric-thermal coupling unit, an SOEC hydrogen production unit, a carbon capture and feedstock pretreatment unit, and a methanol synthesis and purification unit.

[0035] The solar photovoltaic-electricity-thermal coupling unit consists of a water tank 1, a preheater 2, a parabolic trough solar collector 3, photovoltaic panels 4, and a heat exchanger 5. Water from the water tank 1 is preheated by the preheater 2 before entering the parabolic trough solar collector 3 to absorb solar and thermal energy. The heated water then transfers heat to subsequent units (such as SOEC hydrogen production and methanol synthesis) through the heat exchanger 5. The photovoltaic panels 4 convert solar energy into electrical energy to power the electric heater 6 and other electrical equipment within the system.

[0036] The SOEC hydrogen production unit consists of an electric heater 6 and a solid oxide electrolyzer 7. Photovoltaic power drives the electric heater 6, which, along with the heat transferred from the photovoltaic unit, provides the operating temperature for the solid oxide electrolyzer 7. The electrolyzer 7 uses circulating water (from heat exchanger 5 or water tank 1) as raw material to electrolyze and produce H2, which serves as the hydrogen source for methanol synthesis.

[0037] The carbon capture and raw material pretreatment unit consists of a flue gas collection device 10, a carbon capture device 11, and a by-product collection device 12. The flue gas collection device 10 captures flue gas emitted from chemical plants and steel plants, and the carbon capture device 11 separates CO and CO2 (as carbon sources for methanol synthesis). The remaining components are recovered by the by-product collection device 12. The carbon capture process can also be driven by the waste heat of the solar thermal unit to improve energy utilization.

[0038] The methanol synthesis and purification unit consists of a compressor 8, a water-conducting membrane reactor 9, and a distillation unit 13. H2 produced by SOEC is pressurized by compressor 8 and mixed with CO and CO2 obtained from carbon capture before entering the water-conducting membrane reactor 9. The membrane reactor 9 integrates a catalyst bed and a NaA molecular sieve membrane (e.g., ...). Figure 2 As shown, the catalyst bed promotes the methanol synthesis reaction, and the NaA molecular sieve membrane separates the generated H2O in real time, breaking the reaction equilibrium to increase the yield. After the reaction, the product enters the distillation unit 13 to separate high-purity green methanol. The unreacted gas can be recycled back to the carbon capture unit or the front end of the compressor.

[0039] In operation, the water in tank 1 is first preheated by preheater 2, and then enters parabolic trough solar collector 3 to further absorb solar heat. The heated water then transfers heat to the SOEC hydrogen production unit and methanol synthesis unit through heat exchanger 5. Simultaneously, photovoltaic panels 4 convert solar energy into electrical energy, providing power to electric heater 6 and other electrical equipment. Electric heater 6 uses electrical energy to further increase the temperature of solid oxide electrolysis cell 7 to its operating temperature. Solid oxide electrolysis cell 7 uses circulating water as raw material to perform water electrolysis, generating hydrogen. The generated hydrogen is pressurized by compressor 8 and mixed with CO and CO2 separated by carbon capture device 11 to form methanol synthesis. The raw material gas is collected by flue gas collection device 10 from the flue gas emitted by chemical plants or steel plants. After passing through carbon capture device 11, CO and CO2 are separated. The remaining components are collected by by-product collection device 12. The carbon capture process can be driven by the waste heat of the photothermal unit to improve energy utilization. The mixed raw material gas enters water conduction membrane reactor 9, where methanol synthesis reaction occurs in the catalytic bed. The water generated during the reaction is quickly separated and removed through NaA molecular sieve membrane, breaking the reaction equilibrium limit and improving the yield and selectivity of methanol. The product after the reaction enters distillation device 13 for separation to obtain high-purity green methanol. The unreacted gas can be recycled back to the carbon capture or compressor front end for reuse.

[0040] Preferred Solution: Solar Photovoltaic-Electric-Thermal Coupling Unit: Water from tank 1 flows through a DN50 pipe into the spiral tube heat exchange channel of preheater 2. After preheating to 60-80℃, it enters the parabolic trough solar collector 3 through a DN32 pipe. The collector focuses the solar heat onto the absorber tubes via parabolic reflection, raising the water temperature to 150-200℃. As the high-temperature water passes through the shell side of heat exchanger 5, it transfers heat to the SOEC feed water and methanol synthesis raw material gas in the tube side. Photovoltaic panels 4 pass through a 4mm... 2 The cable supplies power to the electric heater 6 (50-100kW) and compressor 8 (3000-5000rpm); SOEC hydrogen production unit: The finned heating element of the electric heater 6 is installed in the outer shell interlayer of the solid oxide electrolyzer 7, working in conjunction with the heat energy provided by the photothermal unit to maintain the electrolyzer temperature at 750-850℃. Circulating water is introduced into the electrolyzer at a pressure of 0.1-0.2MPa, and the reaction occurs under electrode catalysis: H2O + electrical energy → H2 + 0.5O2, with a hydrogen yield of 0.5-0.8Nm. 3 / h; Carbon capture and raw material pretreatment unit: Exhaust fan of flue gas collection device 10 (air volume 500-1000 Nm³ / h) 3The steel plant flue gas (temperature 80-120℃) is fed into the carbon capture device 11 through a DN100 pipeline. The pretreatment unit in the device first removes dust and acidic gases through a water washing tower. The adsorption unit uses activated carbon to adsorb CO2 and molecular sieves to adsorb CO. The desorption unit releases high-purity CO / CO2 (purity ≥95%) through steam heating (180℃). Byproducts (N2, H2O, etc.) are stored in a storage tank after passing through a gas-liquid separator (working pressure 0.3MPa). The methanol synthesis and refining unit: Compressor 8 mixes H2 (pressure increased to 5-8MPa) with the carbon source gas and sends it to the water-conducting membrane reactor 9. The temperature of the catalyst bed (filled with Cu-Zn-Al catalyst) in the reactor is maintained at 220-260℃. A NaA molecular sieve membrane (area 5-10m²) is used. 2 H2O is separated in real time. The reaction product is then distilled in a three-tower distillation unit (13) (pre-distillation tower, pressurized distillation tower, and atmospheric distillation tower) to obtain methanol with a purity of 99.95%. Unreacted gas is passed through a circulating pump (flow rate 100-200 Nm³). 3 / h) Return to compressor inlet; For the first time, the three forms of energy—light, electricity, and heat—are integrated into the same system through a pipeline-cable network, realizing the gradient utilization of solar energy. Compared with traditional single light-thermal or photovoltaic systems, the comprehensive energy utilization rate is increased by 25 percentage points, solving the defect of single energy form in existing technologies.

[0041] Example 2

[0042] Based on Example 1, the energy recovery and utilization of the system were further optimized.

[0043] In the solar photovoltaic-electric-thermal coupling unit, the parabolic trough solar collector 3 and the photovoltaic panel 4 construct a photovoltaic-electric-thermal synergistic mechanism. The solar collector 3 outputs solar energy to drive the solid oxide electrolysis cell 7 and preheat the methanol synthesis raw materials, while the photovoltaic panel 4 outputs electrical energy to supply equipment such as the electric heater 6 and the compressor 8. This achieves complementary energy output from multiple forms of solar energy, reducing the system's dependence on traditional energy sources.

[0044] In the carbon capture and raw material pretreatment unit, the flue gas collection device 10 is directly connected to the flue gas emission end of the chemical plant and steel plant, and the carbon capture device 11 efficiently captures and recovers CO and CO2 in the flue gas. This not only reduces industrial carbon emissions, but also provides a carbon source for methanol synthesis, thus constructing a carbon cycle link of "industrial flue gas carbon capture - green methanol synthesis".

[0045] In the methanol synthesis and purification unit, the water-conducting membrane reactor 9 employs a synergistic structure of a catalytic bed and a NaA molecular sieve membrane. A mixed gas of H2 / CO / CO2 undergoes a methanol synthesis reaction within the catalytic bed, and the generated H2O is rapidly separated and removed through the NaA molecular sieve membrane. This breaks the reaction equilibrium constraint and significantly improves the selectivity and efficiency of methanol synthesis.

[0046] In addition, heat exchanger 5 establishes a system energy circulation channel to recover waste heat from units such as water conduction membrane reactor 9 and solid oxide electrolysis cell 7, which is then used to preheat the water output from water preheating tank 1, thereby achieving energy recycling and improving the overall energy utilization efficiency of the system.

[0047] The system operates as follows: Solar energy is converted into heat and electricity through parabolic trough collector 3 and photovoltaic panels 4, providing heat and electricity to the SOEC hydrogen production unit. The SOEC hydrogen production unit uses this energy to dissociate water into hydrogen and oxygen. The generated hydrogen is pressurized by compressor 8 and mixed with CO and CO2 captured by carbon capture device 11, then enters water conduction membrane reactor 9 for methanol synthesis. During the reaction, NaA molecular sieve membrane separates the generated water in real time, improving the methanol yield. The product after the reaction is separated by distillation device 13 to obtain high-purity methanol. Unreacted gas is recycled back to the system to continue participating in the reaction. The entire system realizes the efficient utilization of solar energy, the recovery and utilization of carbon resources in industrial flue gas, and the large-scale production of green methanol, with significant energy saving and emission reduction effects.

[0048] Preferred Scheme: Water-conducting membrane reactor 9 structure: Synergistic layout of catalyst bed and membrane: Reactor 9 adopts an axially fixed bed structure. The catalyst bed is filled with Cu-Zn catalyst with a particle size of 3-5mm. The NaA molecular sieve membrane is nested in the center of the catalyst bed in a tubular structure. The gap between the outer wall of the membrane tube and the catalyst bed is ≤2mm, ensuring that the H2O generated by the reaction is separated through the membrane pores (pore size 0.38nm) within 0.1-0.2s. The membrane permeate side maintains a negative pressure of 0.1-0.05MPa, and the H2O separation efficiency reaches over 90%. Photovoltaic-thermal synergistic energy supply: The high-temperature heat transfer oil (250-300℃) of the parabolic trough collector 3 preheats the feed gas to 20℃ through the jacket. At 0℃, a photovoltaic-powered electric heater 6 compensates for the heat deficit during nighttime or cloudy days, ensuring that the reaction temperature fluctuates by ≤±5℃. By breaking the reaction equilibrium through membrane separation, the hydrogen-to-carbon ratio (H2 / (CO+2CO2)) of methanol synthesis can be reduced to 2.0-2.2 (compared to 2.5-3.0 in the traditional method), increasing hydrogen utilization from 60% to 85%, and increasing the methanol content in the product from 8-10% in the traditional reactor to 18-20%, significantly reducing the energy consumption of subsequent separation. The catalytic reaction and membrane separation process are integrated in the same equipment, breaking through the traditional step-by-step "reaction-separation" model. Through the synergistic design of membrane pore size and catalytic activity, real-time removal of products is achieved.

[0049] Flue gas collection device 10: Employs a Venturi flue gas duct (throat diameter DN80), with a built-in induced draft fan (pressure 2000-3000Pa). Temperature sensors (range 0-200℃) and pressure sensors (range 0-0.1MPa) are installed at the duct's front end to monitor flue gas parameters in real time. The inner wall of the duct is coated with an anti-corrosion coating (PTFE) to withstand the corrosive environment of SO2 (≤500ppm) in the flue gas. Carbon capture device 11: Pretreatment unit: Includes a three-stage scrubbing tower. The first-stage water scrubbing tower (packing height 3m) removes dust (efficiency ≥99%), and the second-stage alkaline scrubbing tower (NaOH concentration 5-10%) removes SO2 (efficiency ≥95%). %), the three-stage drying tower (silica gel packing) reduces the humidity of flue gas to ≤1%; adsorption unit: two towers in parallel pressure swing adsorption (PSA) are used, tower A adsorbs (pressure 2-3MPa) while tower B desorbs (pressure 0.1-0.2MPa), the adsorbent is 13X molecular sieve (adsorption capacity for CO2 15-20mmol / g), the cycle is 60-120s; desorption unit: the adsorbent is heated to 150℃ by steam to release CO / CO2 mixture (volume ratio CO:CO2=1:1.5), and after passing through the cooler (outlet temperature 40-50℃) it is sent to the compressor (8); by-product collection device 12: gas-liquid separator (volume 5m 3 The system incorporates baffles to separate condensate (containing trace amounts of heavy metals) from non-condensable gases (N2, O2, etc.) in flue gas. The condensate is reused after being filtered by activated carbon, while the non-condensable gases are compressed (1.5 MPa) and stored in an inert gas storage tank. It achieves a carbon capture efficiency of 85-90% for industrial flue gas, with a CO / CO2 concentration ≥95% in the captured carbon source, meeting the requirements for methanol synthesis. Simultaneously, the byproduct recovery rate is ≥90%, avoiding secondary pollution. Each ton of methanol production can reduce industrial carbon emissions by 1.8-2.2 tons. The system employs a chain structure of "pretreatment-adsorption-desorption-byproduct recovery," solving the problem of low carbon capture efficiency caused by the complex composition of industrial flue gas (containing dust and acidic gases). In particular, through the PSA process and the selection of adsorbents, it achieves highly efficient CO / CO2 separation, reducing energy consumption by 30% compared to the traditional amine absorption method.

[0050] Multi-stage heat exchange in heat exchanger 5: Plate heat exchangers are used (heat exchange area 50-100m²) 2The primary side is connected to the high-temperature water (180-200℃) of the parabolic trough collector 3, and the secondary side is divided into two paths: one path heats the SOEC feed water (from 25℃ to 150℃), and the other path preheats the methanol synthesis feed gas (from 40℃ to 180℃); simultaneously, the reaction heat (230-250℃) of the water-conducting membrane reactor 9 is preheated to the water in the hot water tank 1 through another heat exchanger 5 (from 15℃ to 60℃), and the waste heat (450-500℃) of the SOEC hydrogen production unit 7 is used for the desorption process (heating steam) of the carbon capture device 11; unreacted gas circulation: the unreacted gas discharged from the distillation unit 13 (H2 60-70%, CO) 20-25% (CO2 5-10%) is pressurized by a circulating pump (50-80m head) and returned to the compressor inlet 8, with a circulation ratio of 1:3-1:5, increasing the raw material utilization rate from 60% in the traditional system to over 90%; the overall thermal efficiency of the system increases from 45% to 70%; the comprehensive energy consumption (equivalent to standard coal) per ton of methanol production decreases from 2.8 tons to 2.1 tons; and the water resource recycling rate reaches over 95%, significantly reducing operating costs; a three-level energy circulation network of "photothermal-reaction heat-electrolysis waste heat" is constructed, and the energy is utilized in stages through the topological layout of the heat exchanger, overcoming the technical defects of direct waste heat emission in the existing system.

[0051] SOEC Temperature Control: Preheater 2 utilizes the waste heat from heat exchanger 5 to heat the inlet water to 80-100℃, parabolic trough collector 3 further raises the temperature to 150-180℃, and electric heater 6 supplements the temperature to 200-220℃ when sunlight is insufficient, ensuring that the water temperature entering electrolysis cell 7 matches its operating temperature requirements, and maintaining the electrolysis efficiency at 85-90%; Membrane Reactor Process Parameters: The catalytic bed temperature (220-260℃), reaction pressure (5-8MPa), and membrane separation negative pressure (0.05-0.1MPa) are adjusted in real time by a PLC control system. When the CO2 proportion in the feed gas exceeds 30%, the H2 / CO2 ratio is automatically adjusted to 3:1 to ensure methanol selectivity ≥92%. Carbon capture process optimization: The adsorption process is automatically switched according to the CO concentration (10-25%) in the flue gas: temperature swing adsorption (TSA) is used for high concentrations and pressure swing adsorption (PSA) is used for low concentrations, reducing adsorbent regeneration energy consumption by 15-20%; through multi-unit temperature coordinated control, the system can operate stably under different lighting conditions (sunny day, cloudy day, night), and the matching efficiency of SOEC hydrogen production and methanol synthesis reaches over 90%, improving the adaptability of the carbon capture device and enabling it to handle flue gas from different industrial sources; a closed-loop temperature control system with photothermal-electrothermal synergy is designed to solve the problem of system instability caused by intermittent solar energy, and through intelligent adjustment of process parameters, efficient operation under all operating conditions is achieved.

[0052] The working principle of this invention is:

[0053] Energy Conversion and Transfer Process: 1. Solar Energy Capture and Conversion: The parabolic trough solar collector 3 focuses sunlight onto the heat absorber tube through parabolic reflection, heating the water to 150-200℃ to form a high-temperature heat flow; the photovoltaic panel 4 converts light energy into electrical energy (efficiency 18-22%) to power the electric heater 6, compressor 8, and other equipment; 2. Cascaded Utilization of Thermal Energy: The high-temperature heat flow is divided into two paths through the heat exchanger 5: one path heats the SOEC inlet water to 200℃, working in conjunction with the electric heater 6 to maintain the temperature of the electrolysis cell 7 at 750-850℃, driving the water electrolysis reaction; the other path preheats the methanol synthesis raw material gas to 180℃, reducing reaction energy consumption; 3. Electrical Energy Distribution Mechanism: Photovoltaic power is preferentially supplied to the electric heater 6 to compensate for insufficient light and heat, and the remaining electrical energy drives the compressor 8 (pressurizing H2 / CO / CO2 to 5-8MPa), circulating pump, and other moving equipment, realizing the complementary utilization of light and electrical energy;

[0054] Material Conversion and Recycling Process: 1. Industrial Flue Gas Carbon Capture: Flue gas collection device 10 sends flue gas (containing 20-40% CO / CO2) from steel mills / chemical plants to carbon capture device 11. After pretreatment to remove impurities, high-purity CO / CO2 is separated through PSA / TSA process, and by-products (N2, H2O) are recycled; 2. Green Hydrogen and Green Carbon Synthesis of Methanol: H2 generated by SOEC hydrogen production unit 7 is mixed and pressurized with CO / CO2 from carbon capture in compressor 8, and then enters water-conducting membrane reactor 9, where a reaction occurs under the action of a catalytic bed. CO + 2H2 → CH2OH (ΔH = -90.7 kJ / mol), CO2 + 3H2 → CH2OH + H2O (ΔH = -49.0 kJ / mol). The NaA molecular sieve membrane separates H2O in real time, shifting the reaction equilibrium to the right and increasing the methanol yield. 3. Product purification and raw material recycling: The reaction products are separated into high-purity methanol by the distillation unit 13. The unreacted H2 / CO / CO2 is returned to the compressor 8 through the circulation pump. The raw material utilization rate is over 90%, forming a closed-loop chain of "carbon capture-synthesis-recycling".

[0055] System collaborative operation mechanism: 1. Photovoltaic-electrical-thermal synergistic drive: On sunny days, photovoltaic power provides 80% of the heat required by SOEC, and photovoltaic power meets 60% of the electricity demand; on cloudy days, electric heater 6 supplements the photovoltaic power gap, and the photovoltaic power stored in the battery maintains the system operation, realizing continuous production around the clock; 2. Reaction-separation-energy recovery coupling: Membrane reactor 9 integrates the reaction and separation processes, reducing energy consumption in intermediate links; heat exchanger 5 recovers waste heat and reaction heat from electrolysis, which are used to preheat raw materials and for carbon capture and desorption, forming an energy self-circulation system; 3. Industrial carbon cycle closed loop: per ton Methanol production consumes 1.8-2.2 tons of industrial flue gas carbon, equivalent to reducing net CO2 emissions by 0.8-1.0 tons. At the same time, the produced green methanol can be used as a chemical raw material or fuel to replace fossil energy, forming a negative carbon industrial chain of "carbon capture-methanol production-carbon utilization". Through system innovation of multi-energy complementarity, membrane reaction enhancement and industrial carbon cycle, the high carbon bottleneck of traditional methanol production is broken through, providing a feasible path for the low-carbon transformation of the chemical and steel industries. After large-scale application, methanol production costs can be reduced and carbon emissions can be reduced, with significant environmental and economic benefits.

[0056] The specific embodiments described herein are merely illustrative examples of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention.

[0057] Although this document frequently uses terms such as water tank 1, preheater 2, parabolic trough solar collector 3, photovoltaic panel 4, heat exchanger 5, electric heater 6, solid oxide electrolysis cell 7, compressor 8, water conduction membrane reactor 9, flue gas collection device 10, carbon capture device 11, by-product collection device 12, and distillation device 13, the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A solar-driven methanol synthesis and water electrolysis coupled system, characterized in that, include: The solar photovoltaic-electric-thermal coupling unit consists of a water tank (1), a preheater (2), a parabolic trough solar collector (3), a photovoltaic panel (4), and a heat exchanger (5). The outlet of the water tank (1) is connected to the inlet of the preheater (2) through a pipe. The outlet of the preheater (2) is connected to the inlet of the parabolic trough solar collector (3) through a pipe. The outlet of the parabolic trough solar collector (3) is connected to the heat inlet of the heat exchanger (5) through a pipe. The photovoltaic panel (4) is electrically connected to the electric heater (6) and other electrical equipment in the system through a cable. The SOEC hydrogen production unit consists of an electric heater (6) and a solid oxide electrolyzer (7). The electric heater (6) is connected to the heat source inlet of the solid oxide electrolyzer (7) through a pipe. The water inlet of the solid oxide electrolyzer (7) is connected to the water outlet of the heat exchanger (5) or the water tank (1) through a pipe. The carbon capture and raw material pretreatment unit consists of a flue gas collection device (10), a carbon capture device (11), and a by-product collection device (12). The flue gas outlet of the flue gas collection device (10) is connected to the inlet of the carbon capture device (11) through a pipe. The carbon source outlet of the carbon capture device (11) is connected to the methanol synthesis and refining unit through a pipe. The by-product outlet of the carbon capture device (11) is connected to the inlet of the by-product collection device (12) through a pipe. The methanol synthesis and refining unit consists of a compressor (8), a water-conducting membrane reactor (9), and a distillation unit (13). The inlet of the compressor (8) is connected to the hydrogen outlet of the solid oxide electrolysis cell (7) and the carbon source outlet of the carbon capture device (11) through a pipeline. The outlet of the compressor (8) is connected to the raw material inlet of the water-conducting membrane reactor (9) through a pipeline. The product outlet of the water-conducting membrane reactor (9) is connected to the inlet of the distillation unit (13) through a pipeline. The unreacted gas outlet of the distillation unit (13) is circulatedly connected to the inlet of the compressor (8) through a pipeline.

2. The solar-driven methanol synthesis and water electrolysis coupled system according to claim 1, characterized in that, The water-conducting membrane reactor (9) is equipped with a catalytic bed and a NaA molecular sieve membrane. The NaA molecular sieve membrane is located on the reaction product flow path of the catalytic bed and is used to separate the H2O generated by the reaction in real time.

3. The solar-driven methanol synthesis and water electrolysis coupled system according to claim 1, characterized in that, The solar thermal output end of the parabolic trough solar collector (3) is connected to the heat source inlet of the solid oxide electrolysis cell (7) and the preheating pipe of the methanol synthesis raw material through a pipe. The power output end of the photovoltaic panel (4) is electrically connected to the electric heater (6) and the compressor (8) through a cable.

4. The solar-driven methanol synthesis and water electrolysis coupled system according to claim 1, characterized in that, The flue gas collection device (10) includes a flue gas duct and an induced draft fan. One end of the flue gas duct is connected to the flue gas emission end of a chemical plant or steel plant, and the other end is connected to the inlet pipe of the carbon capture device (11) through the induced draft fan.

5. The solar-driven methanol synthesis and water electrolysis coupled system according to claim 4, characterized in that, The carbon capture device (11) includes a pretreatment unit, an adsorption unit and a desorption unit connected in sequence. The inlet of the pretreatment unit is connected to the outlet pipe of the flue gas collection device (10), the carbon source outlet pipe of the desorption unit is connected to the inlet of the compressor (8), and the by-product outlet pipes of the pretreatment unit and the adsorption unit are connected to the inlet of the by-product collection device (12).

6. The solar-driven methanol synthesis and water electrolysis coupled system according to claim 5, characterized in that, The by-product collection device (12) includes a gas-liquid separator and a storage tank. The by-product outlet pipe of the carbon capture device (11) is connected to the gas-liquid separator and the storage tank in sequence. The gas discharge port and liquid collection port of the gas-liquid separator are respectively connected to the corresponding inlet of the storage tank.

7. The solar-driven methanol synthesis and water electrolysis coupled system according to claim 1, characterized in that, The heat inlet of the heat exchanger (5) is connected to the outlet of the parabolic trough solar collector (3), the heat outlet is connected to the heat source inlet of the solid oxide electrolysis cell (7) and the raw material preheating pipe of the water conduction membrane reactor (9), the water inlet of the heat exchanger (5) is connected to the drain outlet of the water tank (1) or the solid oxide electrolysis cell (7), and the water outlet is connected to the inlet of the preheater (2).

8. The solar-driven methanol synthesis and water electrolysis coupled system according to claim 1, characterized in that, The inlet water temperature control system of the solid oxide electrolytic cell (7) includes a preheater (2), a parabolic trough solar collector (3) and an electric heater (6). The heat source inlet of the preheater (2) is connected to the heat flow outlet of the heat exchanger (5). The heating element of the electric heater (6) is located inside the shell of the solid oxide electrolytic cell (7) to coordinate the control of the working temperature of the electrolytic cell.

9. The solar-driven methanol synthesis and water electrolysis coupled system according to claim 1, characterized in that, In the methanol synthesis and refining unit, a circulation pump is installed on the unreacted gas outlet pipe of the distillation unit (13). The outlet of the circulation pump is connected to the inlet of the compressor (8) through a pipe to circulate unreacted H2, CO, and CO2 to the water conduction membrane reactor (9).

10. A solar-driven methanol synthesis and water electrolysis coupled system according to claim 1, characterized in that, The desorption unit of the carbon capture device (11) adopts temperature swing adsorption or pressure swing adsorption process, and the pore size of the NaA molecular sieve membrane is 0.3-0.4 nm, which is used to selectively separate H2O molecules.

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