Skid-mounted green methanol dynamic preparation system and polymorphic storage and transportation method

Abstract

The invention discloses a skid-mounted green methanol dynamic preparation system which comprises a double-electrolytic-cell parallel module, a low-concentration COdirect use module, a micro-channel methanol synthesis reactor, a three-state storage and transportation switching unit and an intelligent control module. The system responds to electricity price fluctuation through a double-electrolytic-cell parallel module to intelligently produce hydrogen, low-concentration industrial tail gas is directly treated through a composite membrane separation and pressure swing adsorption combined technology, a micro-channel reactor and a high-performance catalyst are adopted, rapid synthesis of methanol through COO is achieved, a liquid state storage and transportation unit, a gas state storage and transportation unit and a solution state storage and transportation unit are integrated, and energy conservation and emission reduction are achieved. Multi-state switching is achieved through intelligent control, and the problems that in the traditional technology, the wind-light-electricity adaptability is poor, the low-concentration COS utilization threshold is high, the storage and transportation form is single, and response is slow are solved.

Description

Technical Field

[0001] This invention relates to a skid-mounted dynamic green methanol preparation system and a multi-state storage and transportation method, belonging to the field of renewable energy and chemical process integration technology. Background Technology

[0002] With the continuous expansion of renewable energy power generation, the volatility and intermittency of wind and solar power are becoming increasingly prominent, leading to significant waste of electricity resources during periods of curtailment, off-peak electricity, and negative electricity prices. Meanwhile, industries such as cement, steel, and thermal power emit large amounts of low-concentration CO2 tail gas (typically 15%–25%). Due to its low carbon concentration and complex impurity composition, traditional carbon capture technologies are energy-intensive and costly, making direct application in chemical synthesis difficult. Green methanol, as an important low-carbon fuel and chemical raw material, urgently requires a solution to the synergistic integration of efficient renewable energy utilization and the resource utilization of carbon from industrial tail gas.

[0003] Existing green methanol production technologies are mainly based on large-scale stationary plants. Their process typically includes: water electrolysis for hydrogen production, CO2 capture and purification of industrial waste gas (concentration >95%), and high-temperature, high-pressure methanol synthesis. This technical route has the following significant drawbacks: Poor adaptability to wind and solar power fluctuations: Traditional devices rely on stable power grids for power supply, and the system startup and regulation response time exceeds 2 hours. This makes it impossible to match short-term and fluctuating power resources during periods of power curtailment and negative electricity prices (usually less than 4 hours), resulting in low utilization of renewable energy. High barriers to entry for industrial exhaust gas utilization: Existing carbon capture technologies (such as amine chemical absorption) require high CO2 concentrations (>90%–95%), and low-concentration exhaust gases require additional high-energy-consuming purification units (energy consumption >1.5 MWh / t CO2), making the system complex and costly to operate. Limited storage and transportation methods and insufficient adaptability to various scenarios: Traditional solutions only support the storage and transportation of liquid methanol, which cannot meet the diversified needs of specific industrial scenarios for gaseous fuels (such as steel reducing agents) and solution raw materials (such as chemical intermediates), thus limiting the cross-industry application of green methanol. The system is not flexible in deployment and has a high investment threshold: the construction cycle of fixed factories is long (6-12 months) and the initial investment is large (over 100 million yuan), making it difficult to quickly deploy and replicate in distributed industrial scenarios (such as parks and ports).

[0004] The aforementioned technical bottlenecks collectively result in high production costs for green methanol (exceeding 4,500 yuan / ton), hindering its large-scale promotion and industrial development. This invention addresses the problems of poor adaptability to wind and solar power fluctuations, difficulty in utilizing low-concentration industrial waste gas, limited storage and transportation options, and system response lag in existing technologies. It proposes a skid-mounted dynamic green methanol preparation system and a multi-mode storage and transportation method. Summary of the Invention

[0005] The purpose of this invention is to provide a skid-mounted dynamic green methanol preparation system and a multi-state storage and transportation method for green methanol. This invention aims to solve the core problems in existing green methanol preparation technologies, such as poor adaptability to wind and solar power fluctuations, high threshold for utilizing low-concentration industrial tail gas, single storage and transportation mode, and system response lag. Through the synergistic innovation of core technologies such as wind and solar power fluctuation drive, direct use of low-concentration CO2, modular skid-mounting, and multi-state storage and transportation, this invention achieves comprehensive improvements over traditional technologies in terms of cost, energy efficiency, response speed, flexibility, and environmental protection.

[0006] To solve the above technical problems, the present invention adopts the following technical solution: a skid-mounted dynamic green methanol preparation system, comprising: The dual-electrolyte parallel module includes a proton exchange membrane electrolyzer and an anion exchange membrane electrolyzer connected in parallel. It is used to dynamically allocate the hydrogen production load according to the electricity price fluctuation signal. The proton exchange membrane electrolyzer has a hydrogen production purity of >99.95% and a power of 100–80 kW. The dynamic load allocation improves the green electricity utilization rate by more than 30%. The low-concentration CO2 direct-use module includes a composite membrane separation unit and a pressure swing adsorption unit. The input end of the composite membrane separation unit is used to input low-concentration industrial tail gas, and its output end is connected to the pressure swing adsorption unit. This module is used to directly treat industrial tail gas with a CO2 concentration of 15% to 25%, enriching CO2 to more than 85% and removing impurities simultaneously. The capture energy consumption is reduced to 0.75MWh / t CO2, eliminating the need for high-purity purification steps. A microchannel methanol synthesis reactor, the inner wall of which is coated with a core-shell structure or a composite structure catalyst, wherein the pressure swing adsorption unit, the proton exchange membrane electrolyzer and the anion exchange membrane electrolyzer are all connected to the microchannel methanol synthesis reactor to realize the rapid synthesis reaction of CO2 and H2; The three-state storage and transportation switching unit includes a liquid storage tank, a gaseous storage tank, and a methanol-water solution storage tank. The liquid storage tank, gaseous storage tank, and methanol-water solution storage tank are connected in parallel to the output end of the microchannel methanol synthesis reactor to realize the dynamic switching and storage of methanol in liquid, gaseous and solution states. The intelligent control module is connected to the parallel module of the dual electrolyzers, the low-concentration CO2 direct-use module, the microchannel methanol synthesis reactor, and the three-state storage and transportation switching unit. Based on the mixed integer nonlinear programming algorithm, it is used to link the electricity price signal, tail gas concentration, inventory status and synthesis parameters in real time to realize full-process automation and economic optimization control.

[0007] In the aforementioned system, in the parallel dual-electrolyte module, the proton exchange membrane electrolyzer is preferentially started during the power curtailment period, while the anion exchange membrane electrolyzer is adapted to operate during off-peak hours, and the electricity price fluctuation trigger threshold is 0.05 yuan / kWh.

[0008] In the aforementioned system, the combination of the composite membrane separation unit and the pressure swing adsorption unit can reduce the energy consumption for CO2 capture to below 0.75 MWh / t CO2, and remove SO2, HCl, NOx, and H2S impurities to the ppm level.

[0009] In the aforementioned system, the width of the microchannel methanol synthesis reactor channel is 1.5 mm.

[0010] In the aforementioned system, the catalyst is any one of Cu / ZnO@ZrO2 core-shell catalyst, MnOx-CeO2 composite catalyst, or Cu / ZnO@ZrO2 / MnOx hierarchical porous catalyst.

[0011] In the aforementioned system, the temperature of the liquid storage tank is -20℃, the pressure of the gaseous storage tank is 0.5 MPa, and the concentration of the methanol-water solution in the methanol-water solution storage tank is 40%. The liquid storage tank, the gaseous storage tank, and the methanol-water solution storage tank are switched between their respective states through an electric ball valve, a proportional regulating valve, and a dynamic pressure compensation algorithm.

[0012] In the aforementioned system, the output ends of the proton exchange membrane electrolyzer and the anion exchange membrane electrolyzer are connected to a buffer tank. The buffer tank is connected to the output end of the pressure swing adsorption unit via a proportioning mixer. The output end of the proportioning mixer is connected to the microchannel methanol synthesis reactor.

[0013] A method for multi-state storage and transportation of green methanol based on wind and solar power fluctuations includes the following steps: S1. Responding to wind and solar power fluctuation signals, the hydrogen production load of the proton exchange membrane electrolyzer and the anion exchange membrane electrolyzer is dynamically allocated through the dual electrolyzer parallel module; S2. Directly treat industrial exhaust gas with CO2 concentration of 15% to 25%, enrich CO2 to more than 85% and remove impurities through composite membrane separation and pressure swing adsorption. S3. In a microchannel methanol synthesis reactor, enriched CO2 and H2 are synthesized into methanol in a molar ratio of 3:1 under the action of a catalyst, and the reaction residence time is 15–20 minutes. S4. Based on the needs of downstream application scenarios, methanol is dynamically switched to liquid, gas or methanol-water solution for storage and transportation through a three-state storage and transportation switching unit. S5. Based on a mixed-integer nonlinear programming algorithm, it optimizes electricity prices, exhaust gas concentrations, inventory, and production parameters in real time to achieve economical system operation.

[0014] In the aforementioned method, in step S1, the proton exchange membrane electrolyzer is started first during the power waste period, and switched to the anion exchange membrane electrolyzer during the off-peak period, with hydrogen purity greater than 99.95%.

[0015] In the aforementioned method, the catalyst used in the microchannel methanol synthesis reactor in step S3 is prepared by sol-gel method, co-precipitation method or atomic layer deposition method, with a CO2 single-pass conversion rate greater than 50% and a methanol selectivity greater than 95%.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: This invention achieves an economic breakthrough in green methanol production by coupling fluctuating, low-cost green electricity with the direct utilization of low-concentration industrial waste gas, significantly reducing raw material costs. Experimental data shows that the unit methanol production cost is reduced to 1820-1880 yuan / ton, which is about 53%-60% lower than that of traditional stationary plants (cost > 4500 yuan / ton). This demonstrates economic competitiveness with traditional fossil fuel routes and shows great potential for industrial application. This invention greatly improves the absorption capacity and system response speed of renewable energy. It innovatively adopts a parallel dual electrolyzer parallel structure and intelligent load distribution strategy, enabling the system to quickly respond to short-term electricity price signals such as power curtailment and off-peak electricity. The entire process response time from electricity price triggering to stable methanol production is shortened to less than 15 minutes, far exceeding the more than 120 minutes of traditional technology, realizing the "on-demand" power generation of wind and solar power and effectively solving its volatility problem. This invention overcomes the bottleneck of direct utilization of low-concentration, impurity-containing industrial tail gas. Through a combination of composite membrane separation and pressure swing adsorption, it can directly treat industrial tail gas with a CO2 concentration of only 15%-25% and enrich it to over 85%. At the same time, it deeply removes impurities such as SO2, NOx, HCl, and H2S to the ppm level. This process eliminates the need for traditional high-energy-consuming purification steps, significantly reducing CO2 capture energy consumption from 1.8-2.0 MWh / t CO2 in traditional technologies to below 0.75 MWh / t CO2, a reduction of over 58%. This invention enhances the system's flexibility, adaptability, and ease of deployment. Firstly, it improves production flexibility by employing a microchannel reactor and a high-performance core-shell / composite catalyst, reducing reaction residence time to 15-20 minutes. The system can be rapidly started and stopped, perfectly adapting to fluctuating production conditions. Secondly, it utilizes a three-state storage and transportation system—liquid (-20℃), gaseous (0.5 MPa), and methanol-water solution (40%)—allowing for dynamic, low-energy switching based on downstream needs, significantly expanding the application scope of green methanol. Furthermore, the entire system employs a modular skid-mounted design, enabling on-site installation and commissioning within 7 days, greatly shortening the deployment cycle compared to traditional fixed units, making it particularly suitable for rapid deployment in distributed, temporary scenarios. This invention ensures the long-term reliability and high efficiency of the system. The high-performance catalyst used is prepared through advanced processes, possessing excellent resistance to impurity poisoning and stability, with a lifespan exceeding 5000 hours. This ensures efficient and stable operation with a CO2 single-pass conversion rate >50% and methanol selectivity >95%. Combined with an intelligent control center based on the MINLP algorithm, it achieves multi-objective optimization and automated operation throughout the entire process. The system's carbon footprint is less than 0.52 t CO2 / t MeOH, demonstrating significant environmental benefits. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the overall system structure and process flow of the present invention; Figure 2 This is the intelligent control logic data flow diagram of the present invention.

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0019] Example 1 of the present invention: A skid-mounted dynamic green methanol preparation system, comprising: The dual-electrolyte parallel module includes a proton exchange membrane electrolyzer and an anion exchange membrane electrolyzer connected in parallel. It is used to dynamically allocate hydrogen production load according to electricity price fluctuation signals. The proton exchange membrane electrolyzer has a hydrogen production purity of >99.95% and a power of 100–80 kW. Dynamic load allocation improves green electricity utilization by more than 30%. The proton exchange membrane electrolyzer (PEM) is preferentially started during the curtailment period, while the anion exchange membrane electrolyzer (AEM) is adapted to operate during off-peak hours. The electricity price fluctuation trigger threshold is 0.05 yuan / kWh. The low-concentration CO2 direct-use module includes a composite membrane separation unit and a pressure swing adsorption (PSA) unit. The input end of the composite membrane separation unit is used to input low-concentration industrial exhaust gas, and its output end is connected to the PSA unit. This module is used to directly treat industrial exhaust gas with a CO2 concentration of 15% to 25%, enriching CO2 to more than 85% and simultaneously removing impurities. The combination of the composite membrane separation unit and the PSA unit can reduce the CO2 capture energy consumption to below 0.75 MWh / t CO2, and remove SO2, HCl, NOx, and H2S impurities to the ppm level, reducing the capture energy consumption to 0.75 MWh / t CO2 and eliminating the need for high-purity purification steps. A microchannel methanol synthesis reactor has a channel width of 1.5 mm and its inner wall is coated with a core-shell or composite catalyst. The catalyst is any one of Cu / ZnO@ZrO2 core-shell catalyst, MnOx-CeO2 composite catalyst, or Cu / ZnO@ZrO2 / MnOx multi-level porous catalyst. The pressure swing adsorption unit, proton exchange membrane electrolyzer, and anion exchange membrane electrolyzer are all connected to the microchannel methanol synthesis reactor to realize the rapid synthesis reaction of CO2 and H2. The three-state storage and transportation switching unit includes a liquid storage tank, a gaseous storage tank, and a methanol-water solution storage tank. The liquid storage tank, gaseous storage tank, and methanol-water solution storage tank are connected in parallel at the output end of the microchannel methanol synthesis reactor to realize the dynamic switching and storage of methanol between liquid, gaseous, and solution states. The liquid storage tank has a temperature of -20℃, the gaseous storage tank has a pressure of 0.5MPa, and the methanol-water solution storage tank has a methanol-water solution concentration of 40%. The switching between the liquid storage tank, gaseous storage tank, and methanol-water solution storage tank is achieved through an electric ball valve, a proportional regulating valve, and a dynamic pressure compensation algorithm. The intelligent control module is connected to the parallel module of the dual electrolyzers, the low-concentration CO2 direct-use module, the microchannel methanol synthesis reactor, and the three-state storage and transportation switching unit. Based on the mixed integer nonlinear programming algorithm, it is used to link the electricity price signal, tail gas concentration, inventory status and synthesis parameters in real time to realize full-process automation and economic optimization control.

[0020] The output ends of the proton exchange membrane electrolyzer and the anion exchange membrane electrolyzer are connected to a buffer tank. The buffer tank is connected to the output end of the pressure swing adsorption unit via a proportioning mixer. The output end of the proportioning mixer is connected to the microchannel methanol synthesis reactor.

[0021] The system of this invention achieves "on-demand use of surplus electricity" and distributed production of green methanol through modular skid-mounted design, dynamic load allocation and multi-state storage and transportation synergy optimization, reducing the unit cost to RMB 1820–1880 / ton and the carbon footprint to <0.52 t CO2 / t MeOH, demonstrating significant economic benefits and industrialization potential.

[0022] Example 2 of the present invention: A method for multi-state storage and transportation of green methanol based on wind and solar power fluctuations, comprising the following steps: S1. Responding to wind and solar power fluctuation signals, the hydrogen production load of the proton exchange membrane electrolyzer and the anion exchange membrane electrolyzer is dynamically allocated through the dual electrolyzer parallel module; S2. Directly treat industrial exhaust gas with CO2 concentration of 15% to 25%, enrich CO2 to more than 85% and remove impurities through composite membrane separation and pressure swing adsorption. S3. In a microchannel methanol synthesis reactor, enriched CO2 and H2 are synthesized into methanol in a molar ratio of 3:1 under the action of a catalyst, and the reaction residence time is 15–20 minutes. S4. Based on the needs of downstream application scenarios, methanol is dynamically switched to liquid, gas or methanol-water solution for storage and transportation through a three-state storage and transportation switching unit. S5. Based on a mixed-integer nonlinear programming algorithm, it optimizes electricity prices, exhaust gas concentrations, inventory, and production parameters in real time to achieve economical system operation.

[0023] Specifically, in step S1, the proton exchange membrane electrolyzer is started first during the power curtailment period, and the anion exchange membrane electrolyzer is switched during the off-peak period, with the hydrogen purity greater than 99.95%.

[0024] Specifically, the catalyst used in the microchannel methanol synthesis reactor in step S3 is prepared by sol-gel method, co-precipitation method or atomic layer deposition method, with a CO2 single-pass conversion rate of greater than 50% and a methanol selectivity of greater than 95%.

[0025] The method of this invention innovatively designs a three-state storage and transportation switching mechanism of liquid, gas, and methanol-water solution, which is suitable for the needs of multiple scenarios such as cement, steel, and chemical industries. The production cost of methanol by this invention is reduced to RMB 1820-1880 / ton, the deployment cycle is shortened to 7 days, and the carbon footprint is <0.52 t CO2 / t MeOH. It comprehensively breaks through the bottlenecks of traditional technologies in terms of energy efficiency, economy and scenario adaptability, and provides a replicable modular solution for distributed green methanol production.

[0026] The present invention will be further explained below with reference to specific application experiments and comparative examples.

[0027] Example 3: The lime kiln tail gas (CO2 concentration 22%, SO2 50 ppm, HCl 20 ppm) is separated by cyclone separation to remove particulate matter, and then enters the composite membrane separation unit to enrich CO2 to 85%. Then, it is further purified by pressure swing adsorption (PSA) to reduce the concentrations of SO2 and HCl to below 8 ppm.

[0028] Wind / photovoltaic power is fed into a parallel module of PEM and AEM electrolyzers (total power 100–80 kW). The system automatically allocates load based on electricity price fluctuations (PEM is prioritized for periods of curtailment, and AEM is adapted for off-peak periods). The hydrogen production rate is 0.9–1.5 Nm³ / h, with hydrogen purity >99.95%. After passing through a buffer storage tank, the hydrogen is sent to the synthesis system. CO2 and H2 are mixed at a stoichiometric ratio of 3:1 and enter a microchannel methanol synthesis reactor. The reactor channel width is 1.5 mm, and the inner wall is coated with a Cu / ZnO@ZrO2 core-shell catalyst (specific formulation: CuO 40 wt%, ZnO 30 wt%, ZrO2 30 wt%).

[0029] The Cu / ZnO@ZrO2 core-shell catalyst was prepared using a sol-gel method: copper nitrate, zinc nitrate, and zirconium isopropoxide were dissolved in ethylene glycol and heated in an 80°C water bath until gelation occurred. The mixture was then dried at 120°C and calcined at 500°C for 2 h to form a porous support. Finally, a reduction metal precursor (copper nitrate + zinc nitrate) was impregnated, and reduction with H2 at 550°C for 1 h was performed to obtain the active layer. The reaction temperature was controlled at 220°C, the operating pressure was maintained at 8 MPa, and the gas residence time was 15 minutes. After condensation and separation, the liquid crude methanol was purified to over 99.5% in a distillation unit and then temporarily stored in a -20°C cryogenic tank (5 t volume).

[0030] The system integrates an intelligent control module to collect real-time data on electricity price (trigger threshold of 0.05 yuan / kWh), tail gas concentration, and methanol inventory, achieving fully automated response from electricity price detection to methanol production. Experimental results show that the CO2 single-pass conversion rate is 51.3%, the methanol selectivity is 95.8%, the unit methanol production cost is 1850 yuan / ton, and the time from the issuance of the electricity price trigger signal to stable methanol production is 11.8 minutes, meeting the rapid response requirement. This embodiment verifies the feasibility and economy of this invention for the efficient production of green methanol under the coupling conditions of low-concentration industrial tail gas and fluctuating green electricity.

[0031] Example 4: The exhaust gas from the thermal power plant (CO2 concentration 18%, NOx 30 ppm, H2S 10 ppm) is separated by cyclone separation to remove particulate matter, and then enters the membrane separation unit to increase the CO2 concentration to 85%. It is then further purified by pressure swing adsorption (PSA) to reduce the NOx and H2S concentrations to below 3 ppm.

[0032] Wind / photovoltaic power is connected to the PEM and AEM electrolyzer parallel module (total power 100–80 kW). The system automatically allocates the load according to electricity price fluctuations (PEM is given priority for curtailment periods, and AEM is adapted to off-peak periods). The hydrogen production rate is 0.9–1.5 Nm³ / h, and the hydrogen purity is >99.95%. After passing through a buffer storage tank, the hydrogen is sent to the synthesis system.

[0033] CO2 and H2 are mixed at a stoichiometric ratio of 3:1 and fed into a microchannel methanol synthesis reactor. The reactor channel is 1.5 mm wide and its inner wall is coated with a MnOx-CeO2 composite catalyst (specific formulation: MnO2 45 wt%, CeO2 55 wt%).

[0034] The MnOx-CeO2 composite catalyst was prepared by a co-precipitation-calcination method: manganese nitrate and cerium nitrate were dissolved in deionized water, and urea was added as a precipitant. The mixture was stirred in an 80°C water bath until pH=9 to form a precursor precipitate, which was then dried at 120°C and calcined at 600°C for 3 h to form a porous oxide support. Finally, the precipitate was oxidized in air at 550°C for 1 h to obtain the active layer. The reaction temperature was controlled at 240°C, the operating pressure was maintained at 9 MPa, and the gas residence time was 18 minutes. After condensation and separation, the gaseous crude methanol was pressurized to 0.5 MPa in a compression unit and then temporarily stored in a 25°C atmospheric pressure gaseous storage tank (3 t volume).

[0035] The system integrates an intelligent control module to collect real-time data on electricity price (trigger threshold of 0.05 yuan / kWh), tail gas concentration, and methanol inventory, achieving fully automated response from electricity price detection to methanol production. Experimental results show that the CO2 single-pass conversion rate is 50.8%, the methanol selectivity is 96.2%, the unit methanol production cost is 1880 yuan / ton, and the time from the issuance of the electricity price trigger signal to stable methanol production is 9.5 minutes, meeting the rapid response requirement. This embodiment verifies the feasibility and economy of this invention for the efficient production of green methanol under the coupling conditions of low-concentration industrial tail gas and fluctuating green electricity.

[0036] Example 5: After particulate matter is removed from the blast furnace gas (CO2 concentration 25%, CO 5%, CH4 2%) of the steel plant, it enters the composite membrane separation unit to increase the CO2 concentration to 85%, and then undergoes deep purification through pressure swing adsorption (PSA) to reduce the CO and CH4 concentrations to below 0.8%.

[0037] Wind / photovoltaic power is fed into a parallel module of PEM and AEM electrolyzers (total power 100–80 kW). The system automatically allocates load according to electricity price fluctuations (PEM is prioritized for periods of curtailment, and AEM is adapted for off-peak periods). The hydrogen production rate is 0.9–1.5 Nm³ / h, and the hydrogen purity is >99.95%. After passing through a buffer storage tank, the hydrogen is sent to the synthesis system. CO2 and H2 are mixed at a stoichiometric ratio of 3:1 and enter a microchannel methanol synthesis reactor. The reactor channel width is 1.5 mm, and the inner wall is coated with a Cu / ZnO@ZrO2 / MnOx composite catalyst (specific formulation: CuO 35 wt%, ZnO 25 wt%, ZrO2 20 wt%, MnO2 20 wt%).

[0038] The Cu / ZnO@ZrO2 / MnOx composite catalyst was prepared by atomic layer deposition (ALD): Cu(NO3)2·3H2O, Zn(NO3)2·6H2O, zirconium isopropoxide, and Mn(NO3)2·4H2O were used as precursors. Cu / Zn / Zr / Mn oxide layers with a thickness of 5–10 nm were deposited alternately at 200 °C. Finally, H2 reduction was carried out at 550 °C for 1 h to form a hierarchical porous structure. The reaction temperature was controlled at 230 °C, the operating pressure was maintained at 7 MPa, and the gas residence time was 20 min. After condensation and separation, the reaction product was temporarily stored in a 10 t methanol aqueous solution.

[0039] The system integrates an intelligent control module to collect real-time data on electricity price (trigger threshold of 0.05 yuan / kWh), tail gas concentration, and methanol inventory, achieving fully automated response from electricity price recognition to methanol production. Experimental results show that the CO2 single-pass conversion rate is 52.1%, the methanol selectivity is 97.3%, the unit methanol production cost is 1820 yuan / ton, and the time from the issuance of the electricity price trigger signal to stable methanol production is 14.3 minutes, meeting the rapid response requirement. This embodiment verifies the feasibility and economy of this invention for the efficient production of green methanol under complex industrial tail gas (containing CO / CH4 impurities) and mixed green-electric coupling conditions.

[0040] Comparative Example 1: Performance Comparison of Traditional Stationary Methanol Plants The present invention (Example 3) differs significantly from traditional stationary methanol plants in key performance indicators. When using lime kiln tail gas as the carbon source, the methanol yield of the present invention is 51.3%, while that of the traditional plant is 72.5%. Although the absolute value is slightly lower, its production cost is only 1850 yuan / ton, far lower than the 4200 yuan / ton of the traditional plant. Regarding CO2 capture energy consumption, the present invention, through a combination of membrane separation and pressure swing adsorption, achieves an energy consumption of 0.75 MWh / t CO2, a 58% reduction compared to the traditional chemical absorption method (1.8 MWh / t CO2).

[0041] The system response time comparison is particularly significant: Based on a skid-mounted design driven by wind and solar power fluctuations, this invention achieves methanol production within <12 minutes from electricity price triggering, while traditional units rely on a stable power grid, resulting in a response time >120 minutes. Traditional units use only a single linear electrolyzer (such as an alkaline electrolyzer), which cannot achieve dynamic load distribution under PEM / AEM parallel operation, leading to a 30% reduction in capacity during periods of power curtailment. Regarding deployment time, this invention's modular skid-mounted system can be installed and commissioned within 7 days (including pretreatment, electrolysis, synthesis, and storage modules), while traditional stationary units require a 6–12 month construction period. Furthermore, this invention is suitable for direct use scenarios with low-concentration CO2 (15%–25%), eliminating the need for high-purity CO2 purification (>95%), further reducing system complexity and energy consumption.

[0042] Experimental data show that the present invention has significant advantages in terms of economy (cost reduction of 53%), dynamic response capability (10 times improvement) and deployment efficiency (deployment time reduction of 83%), verifying its disruptive breakthrough and industrialization feasibility in the field of renewable energy-based green methanol production.

[0043] Comparative Example 2: Comparison of High-Purity CO2 to Methanol Production Schemes The present invention (Example 3) differs significantly from the high-purity CO2 methanol production route in terms of techno-economic efficiency and application suitability. Regarding CO2 capture energy consumption, the present invention, through a combination of membrane separation (0.4 MWh / t CO2) and pressure swing adsorption (0.35 MWh / t CO2), has a total energy consumption of 0.75 MWh / t CO2, while the high-purity CO2 route relies on chemical absorption (amine solvents), with energy consumption as high as 2.0 MWh / t CO2.

[0044] In the comparison of catalyst lifetimes, the Cu / ZnO@ZrO2 core-shell catalyst of this invention, after being treated with sol-gel method and H2 reduction, has a lifetime of >5000 hours, which is significantly better than the performance of MnOx / CeO2 catalyst in the high-purity CO2 route, which has a lifetime of <3000 hours (affected by impurity poisoning).

[0045] High-purity CO2 production relies on a single type of electrolyzer (such as an alkaline electrolyzer), which cannot adapt to the fluctuating characteristics of wind and solar power, resulting in insufficient system flexibility. In terms of storage and transportation, this invention supports three forms: liquid (−20℃), gaseous (0.5 MPa), and a 40% methanol-water solution. This adapts to the needs of various scenarios, including cement plants (liquid methanol fuel), steel plants (gaseous reducing agent), and chemical plants (solution feedstock). High-purity CO2 production, however, can only produce liquid methanol, limiting its application in non-chemical fields. Furthermore, this invention is designed for low-concentration CO2 (15%–25%), eliminating the need for additional purification to 99.9%, further reducing system complexity and energy consumption. Experimental data show that this invention has significant advantages in CO2 capture energy consumption (reduced by 62.5%), catalyst lifespan (increased by 167%), and scenario adaptability (covering three types of industrial scenarios), validating its technological advancement and industrialization potential in the field of renewable energy-based green methanol production.

[0046] Example 6: Performance Verification of Three-State Storage and Transportation Switching This invention relates to a skid-mounted green methanol system that integrates liquid, gaseous, and solution storage and transportation modes to verify its dynamic switching capability and stability. Under experimental conditions, the liquid methanol storage tank (5 t volume) was set at −20℃ and 0.1 MPa, the gaseous storage tank (3 t volume) was set at 25℃ and 0.5 MPa, and the methanol-water solution storage tank (10 t volume) was set at 40% concentration and 0.2 MPa. Liquid methanol is preferentially matched with the PEM electrolyzer for high-purity hydrogen production, while the gaseous / solution mode is adapted to the AEM electrolyzer for off-peak electricity operation, achieving synergistic optimization of storage and transportation modes and electrolysis modes. The system uses an intelligent control module to monitor the tank pressure, temperature, and liquid level in real time, and achieves three-state switching through a combination of electric ball valves and proportional regulating valves.

[0047] In the switching process, the liquid-to-gas conversion requires starting a cryogenic pump (flow rate 3 m³ / h) to deliver liquid methanol to the vaporizer (heating power 5 kW). After heat exchange, the pressure is increased to 0.5 MPa, completing the filling of the gaseous storage tank. The total time is 12 minutes, with an energy consumption of 0.09 kWh / kg. The liquid-to-solution conversion uses a metering pump (accuracy ±0.5%) to mix methanol and deionized water at a mass ratio of 1:1. After homogenization by a static mixer (800 rpm), the mixture is delivered to the solution storage tank, taking 5 minutes and consuming 0.06 kWh / kg. Both the gas-to-liquid and solution-to-liquid switching are achieved by adjusting the condenser (−20℃) and separator, with a switching time of <8 minutes.

[0048] In stability testing, the system continuously performed 100 three-state cycle switching cycles (liquid → gas → solution → liquid) without any leakage, pressure fluctuations (±0.02 MPa), or performance degradation. Experimental data shows that the energy consumption for switching between the three-state storage and transportation modes is <0.1 kWh / kg, significantly better than traditional single-state storage and transportation (liquid storage tanks require an additional cooling energy consumption of 0.3 kWh / kg). Furthermore, this invention, through modular tank design and a dynamic pressure compensation algorithm, achieves real-time matching between storage and transportation modes and downstream demand, solving the problem of poor scenario adaptability caused by the single-mode methanol storage and transportation in existing technologies. This embodiment verifies the technical feasibility and industrialization potential of this invention in the field of multi-state storage and transportation.

[0049] Summarize: The above embodiments and comparative data show that the present invention, through wind and solar power wave drive, direct use of industrial exhaust gas, modular skid-mounted design, and three-state storage and transportation, is significantly superior to traditional technologies in terms of methanol yield, production cost, response time, and scenario adaptability.

[0050] Table 1. Performance comparison of Embodiments 3–5 of the present invention with the comparative system (core operating parameters and economic indicators)

[0051] Table 2. Comparison of the essential differences between the present invention and existing technologies in terms of technical approach and system characteristics.

[0052] Table 3 Performance verification data for three-state storage and transportation switching (Example 4) .

Claims

1. A skid-mounted green methanol dynamic production system, characterized in that, The application relates to a hydrogen production system, which comprises the following parts: a double-electrolytic-cell parallel module, which comprises a proton exchange membrane electrolytic cell and an anion exchange membrane electrolytic cell arranged in parallel and is used for dynamically distributing hydrogen production load according to an electricity price fluctuation signal; a low-concentration CO2 direct-use module, which comprises a composite membrane separation unit and a pressure swing adsorption unit, the input end of the composite membrane separation unit is used for inputting low-concentration industrial tail gas, the output end of the composite membrane separation unit is connected with the pressure swing adsorption unit, and the module is used for directly processing industrial tail gas with a CO2 concentration of 15% to 25%, enriching CO2 to above 85% and synchronously removing impurities; a micro-channel methanol synthesis reactor, the inner wall of which is coated with a core-shell structure or a composite structure catalyst, the pressure swing adsorption unit, the proton exchange membrane electrolytic cell and the anion exchange membrane electrolytic cell are connected with the micro-channel methanol synthesis reactor, and the module is used for realizing rapid synthesis reaction of CO2 and H2; a three-state storage and transportation switching unit, which comprises a liquid-state storage tank, a gaseous-state storage tank and a methanol aqueous solution storage tank, the liquid-state storage tank, the gaseous-state storage tank and the methanol aqueous solution storage tank are connected in parallel at the output end of the micro-channel methanol synthesis reactor, and the module is used for realizing dynamic switching and storage of methanol among liquid state, gaseous state and solution state; an intelligent control module, which is respectively connected with the double-electrolytic-cell parallel module, the low-concentration CO2 direct-use module, the micro-channel methanol synthesis reactor and the three-state storage and transportation switching unit, is based on a mixed integer nonlinear programming algorithm, is used for real-time linkage of an electricity price signal, tail gas concentration, inventory state and synthesis parameters, realizes automatic control of the whole process and economic optimization control.

2. The system of claim 1, wherein, In the double-electrolytic-cell parallel module, the proton exchange membrane electrolytic cell is preferentially started in an abandoned electricity period, the anion exchange membrane electrolytic cell is adapted to run in a valley electricity period, and the electricity price fluctuation trigger threshold is 0.05 yuan / kWh.

3. The system of claim 1, wherein, The combination of the composite membrane separation unit and the pressure swing adsorption unit can reduce the CO2 capture energy consumption to below 0.75 MWh / t CO2 and remove SO2, HCl, NOx, H2S impurities to ppm level.

4. The system of claim 1, wherein, The channel width of the micro-channel methanol synthesis reactor is 1.5 mm.

5. The system of claim 1, wherein, The catalyst is any one of a Cu / ZnO@ZrO2 core-shell catalyst, a MnOx-CeO2 composite catalyst or a Cu / ZnO@ZrO2 / MnOx multi-stage channel catalyst.

6. The system of claim 1, wherein, The temperature of the liquid-state storage tank is-20 DEG C, the pressure of the gaseous-state storage tank is 0.5 MPa, the methanol aqueous solution concentration in the methanol aqueous solution storage tank is 40%, and the liquid-state storage tank, the gaseous-state storage tank and the methanol aqueous solution storage tank are switched among different states through electric ball valves, proportional regulating valves and dynamic pressure compensation algorithms.

7. The system of claim 1, wherein, The output ends of the proton exchange membrane electrolytic cell and the anion exchange membrane electrolytic cell are connected with a buffer tank, the buffer tank is connected with a proportional mixer at the output end of the pressure swing adsorption unit, and the output end of the proportional mixer is connected with the micro-channel methanol synthesis reactor.

8. A green methanol multi-state storage and transportation method based on wind-solar power fluctuation driving, characterized in that, The application further discloses a hydrogen production method, which comprises the following steps: S1, responding to a wind-solar electricity fluctuation signal, dynamically distributing hydrogen production load of a proton exchange membrane electrolytic cell and an anion exchange membrane electrolytic cell through a double-electrolytic-cell parallel module; S2, directly processing industrial tail gas with a CO2 concentration of 15% to 25%, enriching CO2 to above 85% and removing impurities through composite membrane separation and pressure swing adsorption. S3. In the micro-channel methanol synthesis reactor, the enriched CO2 and H2 are synthesized into methanol under the action of a catalyst at a molar ratio of 3:1, and the reaction residence time is 15-20 minutes; S4. According to the requirements of the downstream application scenarios, the methanol is dynamically switched to be stored and transported in a liquid state, a gaseous state or a methanol aqueous solution through a three-state storage and transportation switching unit; S5. Based on a mixed integer nonlinear programming algorithm, the electricity price, tail gas concentration, inventory and production parameters are optimized in real time to realize economic operation of the system.

9. The method of claim 8, wherein, In the step S1, the proton exchange membrane electrolytic cell is preferentially started during the abandoned electricity period, and the anion exchange membrane electrolytic cell is switched to during the valley electricity period, and the hydrogen purity is greater than 99.95%.

10. The method of claim 8, wherein, The catalyst used in the micro-channel methanol synthesis reactor in the step S3 is prepared by a sol-gel method, a coprecipitation method or an atomic layer deposition method, the CO2 single-pass conversion rate is greater than 50%, and the methanol selectivity is greater than 95%.

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