Syngas Preparation and Methanol Synthesis System and Method Based on the Synergistic Operation of Alkali Tank and SOEC

Abstract

This invention discloses a syngas preparation and methanol synthesis system based on the synergistic operation of alkaline electrolysis and SOEC, belonging to the field of green chemical and energy technology. The system includes: an alkaline electrolysis hydrogen production unit, a solid oxide electrolysis cell unit, a pressure swing adsorption (PSA) unit, a syngas mixing unit, a methanol synthesis unit, and a control unit. The PSA unit is used to purify the SOEC product gas, separating carbon monoxide and returning the enriched carbon dioxide to the SOEC to form a carbon cycle. The control unit is configured to: control the SOEC unit to operate at a reference load, and dynamically adjust the hydrogen production power of the alkaline electrolysis hydrogen production unit based on the carbon monoxide production signal from the PSA unit, thereby ensuring that the molar ratio of hydrogen to carbon monoxide in the syngas output from the syngas mixing unit is stably maintained within a preset target range.

Description

Technical Field

[0001] This application relates to the field of solid oxide electrolyzer technology, and in particular to a synthesis gas preparation and methanol synthesis system and method based on the synergistic operation of an alkaline tank and SOEC. Background Technology

[0002] Solid oxide electrolysis cells (SOECs) are a novel electrochemical technology operating at high temperatures of 600–900 °C. Utilizing the ionic conductivity of solid oxide ceramic electrolytes at high temperatures, they can efficiently electrolyze carbon dioxide (CO2) into carbon monoxide (CO), or co-electrolyze carbon dioxide and water vapor to directly produce syngas (H2+CO). Compared to low-temperature electrolysis technologies, SOECs can utilize thermal energy to drive part of the reaction, significantly reducing electrical energy consumption and thus achieving a higher conversion efficiency from electrical to chemical energy, showing significant potential in the synthesis of green fuels and chemicals.

[0003] In the green methanol synthesis pathway, syngas preparation is a crucial step. The methanol synthesis reaction has strict requirements on the molar ratio of hydrogen (H2) to carbon monoxide (CO) in the syngas, with an ideal specific modulus close to 2.0–2.1. Therefore, how to efficiently, flexibly, and with low carbon emissions prepare syngas that meets this stringent ratio is one of the challenges in realizing the industrialization of green methanol. Existing technologies for syngas preparation using electrochemical methods can be mainly divided into two categories. The first category is based on SOEC co-electrolysis technology, which feeds premixed CO2 and H2O into a high-temperature SOEC stack, directly electrolyzing to produce a mixture of H2 and CO in a one-step process. While this approach can improve energy efficiency by utilizing the advantages of high-temperature thermodynamics, the H2 / CO ratio of the produced syngas is severely limited by the ratio of the inlet feed gas. Due to the high operating temperature of the SOEC, rapidly and accurately adjusting the high-temperature steam flow rate is technically challenging and energy-intensive, making it difficult for the system to flexibly respond to the dynamic gas ratio requirements of downstream methanol synthesis. The second approach combines mature low-temperature water electrolysis for hydrogen production (such as alkaline electrolysis) with reverse water-gas shift (RWGS) chemical reactions. This approach first independently prepares high-purity H2 in a low-temperature electrolyzer, then feeds H2 and CO2 into a separate RWGS reactor, where CO is generated under the action of a catalyst, and finally mixed to obtain syngas. While this approach utilizes the advantages of mature and easily controllable low-temperature electrolysis technology, the system requires the integration of an electrolyzer, an RWGS reactor, and additional heating and separation units, resulting in a complex process flow and high equipment investment and maintenance costs. Furthermore, the RWGS reaction is a reversible endothermic reaction, requiring continuous external heating, and lacks effective thermal energy integration with the low-temperature electrolysis unit, leading to low overall system energy utilization efficiency. Summary of the Invention

[0004] This specification provides an embodiment of a syngas preparation and methanol synthesis system and method based on the synergistic operation of an alkaline tank and SOEC, in order to solve at least one of the technical problems mentioned above.

[0005] To solve the above-mentioned technical problems, the embodiments in this specification are implemented as follows: According to a first aspect of the present invention, a syngas preparation and methanol synthesis system based on the syngas preparation system and SOEC working in tandem is provided, comprising: Alkaline electrolysis hydrogen production unit, used for producing hydrogen by electrolyzing water; A solid oxide electrolytic cell device for producing carbon monoxide by electrolyzing carbon dioxide; The pressure swing adsorption device has its inlet in fluid communication with the mixed gas outlet of the solid oxide electrolysis cell device, and is used to purify the mixed gas so as to output purified carbon monoxide from its first outlet and enriched carbon dioxide from its second outlet. The second outlet of the pressure swing adsorption device is in fluid communication with the carbon dioxide inlet of the solid oxide electrolysis cell device to form a carbon dioxide circulation loop. The syngas mixing device is fluidly connected to the hydrogen outlet of the alkaline electrolysis hydrogen production device and the first outlet of the pressure swing adsorption device, respectively, and is used to mix hydrogen and carbon monoxide to form syngas. A methanol synthesis unit is fluidly connected to the syngas outlet of the syngas mixing unit and is used to catalytically synthesize methanol from the syngas. The control device is connected to the alkaline electrolysis hydrogen production device, the solid oxide electrolysis cell device and the pressure swing adsorption device respectively; The control device is configured to: control the operating load of the solid oxide electrolysis cell device at a reference level, and dynamically adjust the hydrogen production power of the alkaline electrolysis hydrogen production device based on the carbon monoxide production signal from the pressure swing adsorption device, so as to maintain the molar ratio of hydrogen to carbon monoxide in the syngas output by the syngas mixing device within a preset target value range.

[0006] In some optional embodiments, the alkaline electrolysis hydrogen production device includes an electrolyzer, an alkaline circulation system, a gas-liquid separator, and a hydrogen purification system. The solid oxide electrolyzer device includes an SOEC stack, a preheater for preheating the inlet gas, and a heat exchanger integrated with the preheater and / or the SOEC stack. The anode of the SOEC stack is provided with an oxygen outlet. The pressure swing adsorption device includes at least two adsorption towers and a control valve assembly, wherein the control device is configured to control the at least two adsorption towers to alternately perform adsorption and desorption operations. The methanol synthesis apparatus includes a synthesis gas compressor, a methanol synthesis reactor, a separation distillation unit for separating reaction products, and a circulating gas recovery unit for returning unreacted gases to the synthesis gas mixing apparatus.

[0007] In some alternative embodiments, the heat exchanger is used to recover the high-temperature waste heat generated during the operation of the solid oxide electrolysis cell and transfer the recovered heat to carbon dioxide gas flowing through the preheater to achieve thermal energy integration.

[0008] In some alternative implementations, the target value ranges from 2.0 to 2.1.

[0009] In some optional implementations, the control device pre-stores control logic corresponding to four states: system startup, normal operation, standby, and shutdown, and can respond to external signals to coordinate the switching of each device between the above states. Among them, the control logic in the standby state includes controlling the solid oxide electrolytic cell device to maintain a high temperature and perform inert gas purging; The control logic during shutdown includes controlling the methanol synthesis unit to perform passivation treatment on the catalyst.

[0010] In some optional embodiments, it further includes: a renewable energy power interface, connected to the power input terminal of the alkaline electrolysis hydrogen production device and the solid oxide electrolysis cell device, for connecting to at least one of wind power and photovoltaic power generation.

[0011] According to a second aspect of the present invention, a method for preparing syngas and synthesizing methanol using the system described in any of the preceding claims is provided, comprising the following steps: Start-up phase: Control the solid oxide electrolysis cell device to heat up to the operating temperature and power it on to start the pressure swing adsorption device; after the pressure swing adsorption device outputs a stable carbon monoxide gas flow, start the alkaline electrolysis hydrogen production device and adjust its hydrogen production rate so that the mixed syngas reaches the target molar ratio. Normal operation phase: The solid oxide electrolysis cell device is maintained at the reference load, and the hydrogen production rate of the alkaline electrolysis hydrogen production device is dynamically adjusted based on the real-time carbon monoxide flow rate output by the pressure swing adsorption device in order to maintain the target molar ratio; Standby phase: Power supply to the solid oxide electrolysis cell device and the alkaline electrolysis hydrogen production device is stopped, but the high temperature of the solid oxide electrolysis cell device is maintained and inert gas purging is performed, while the adsorption-desorption cycle of the pressure swing adsorption device is stopped. Shutdown phase: Sequentially reduce and stop the operating load of each unit; control the methanol synthesis unit to stop feeding, cool and depressurize, and passivate the catalyst; control the solid oxide electrolysis cell unit to execute a slow cooling program.

[0012] In some alternative implementations, during the normal operation phase, the hydrogen production rate of the alkaline electrolysis hydrogen production device is dynamically adjusted by rapidly regulating the input current of the device.

[0013] According to a third aspect of the present invention, a method for coordinated control of a syngas production and methanol synthesis system is provided, the method comprising: The solid oxide electrolyzer is set to operate at a stable reference load as a reference source for the system's carbon monoxide supply. The alkaline electrolysis hydrogen production unit is configured as a unit with a rapidly adjustable hydrogen production rate; Real-time acquisition of signals reflecting the actual carbon monoxide production of the system; The required real-time hydrogen production is calculated based on the preset target molar ratio of hydrogen to carbon monoxide and the actual carbon monoxide production signal. By rapidly adjusting the operating power of the alkaline electrolysis hydrogen production device, its actual hydrogen production rate is matched with the required real-time hydrogen output, thereby achieving dynamic closed-loop control of the syngas ratio.

[0014] In some alternative embodiments, the signal reflecting the actual carbon monoxide production comes from a pressure swing adsorption device that purifies and measures the flow rate of the gas produced by the solid oxide electrolysis cell.

[0015] One embodiment of this specification can achieve at least the following beneficial effects: 1. The technical solution of this application integrates an alkaline electrolysis hydrogen production unit, a solid oxide electrolysis cell unit, a pressure swing adsorption unit, a syngas mixing unit, a methanol synthesis unit, and a control unit into a single, collaborative system. This solves the problems of inflexible syngas ratio adjustment and complex system structure in traditional technical solutions. By separating the production paths of the hydrogen and carbon sources, this system achieves decoupled production and flexible allocation of hydrogen and carbon monoxide sources, thereby accurately and stably meeting the stringent requirements of methanol synthesis for syngas ratio.

[0016] 2. In the technical solution of this application, the control device dynamically adjusts the operating power of the alkaline electrolysis hydrogen production unit based on the actual carbon monoxide production signal from the system. This mechanism fully utilizes the difference between the rapid response of alkaline electrolysis hydrogen production and the stable operation of solid oxide electrolyzers, forming a coordinated control strategy with stable carbon monoxide production as the benchmark and rapidly adjustable hydrogen production as the variable. This not only enables real-time, high-precision control of the syngas ratio but also allows for rapid response to fluctuations in downstream production demand and upstream renewable energy power while maintaining high system efficiency.

[0017] 3. The technical solution of this application captures unreacted carbon dioxide and returns it to the inlet of the solid oxide electrolysis cell through a pressure swing adsorption device and a circulation pipeline, thus constructing an efficient internal carbon circulation loop. This can improve the overall utilization rate of carbon resources, reduce raw material consumption and carbon emissions, and optimize energy and material utilization efficiency at the system level. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of a syngas preparation and methanol synthesis system based on the synergistic operation of an alkaline tank and SOEC, provided by the present invention; Figure 2 This is an overall structural diagram of a syngas preparation and methanol synthesis system based on the synergistic operation of an alkaline tank and SOEC, provided by the present invention. Figure 3 This invention provides Figure 2 Partial view of power control and current regulation of a medium-alkaline solution electrolysis hydrogen production unit; Figure 4 This invention provides Figure 2 Partial diagram of adsorption-desorption and heat exchange in a pressure swing adsorption unit; Figure 5 This invention provides Figure 2 Partial view of the separation, distillation, and gas circulation in a syngas-to-methanol unit; Figure 6 This is a block diagram of the signal interaction logic of the control unit in the SOEC start-up protective gas circulation purging system of this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of one or more embodiments of this specification clearer, the technical solutions of one or more embodiments of this specification will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of them. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of one or more embodiments of this specification.

[0021] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another.

[0022] Figure 1 This is a flowchart of a syngas preparation and methanol synthesis system based on the syngas production of an alkaline tank and an SOEC working in tandem, provided by the present invention. The flowchart shows that renewable energy (wind power, photovoltaic) supplies power to the alkaline electrolysis unit and the SOEC unit. The alkaline electrolysis unit electrolyzes water to produce hydrogen, and the SOEC unit uses high-concentration CO2 to produce CO. The products of the two are then used to prepare methanol through a syngas to methanol unit. The methanol can be transported to a chemical plant or shipped out by transport ship.

[0023] like Figure 2 As shown, the system provided by this application mainly includes six collaborative functional units. Among them, the alkaline electrolysis hydrogen production unit serves as the system's hydrogen source, used for electrolyzing water to produce hydrogen. The solid oxide electrolysis cell serves as the core of the system's carbon conversion, used for electrolyzing carbon dioxide to produce carbon monoxide. The inlet of the pressure swing adsorption (PSA) unit is fluidly connected to the mixed gas outlet of the PSA unit; its function is to separate and purify the mixed gas, outputting high-purity carbon monoxide product gas from its first outlet and enriched carbon dioxide from its second outlet. By connecting this second outlet to the carbon dioxide inlet of the PSA unit, a highly efficient internal carbon dioxide circulation loop is formed, allowing unreacted carbon dioxide to be recovered and reused. The syngas mixing unit is fluidly connected to both the hydrogen outlet of the alkaline electrolysis hydrogen production unit and the first outlet of the PSA unit, responsible for mixing the two gas streams in a proportional manner to form syngas (H2 + CO). The methanol synthesis unit is connected to the outlet of the syngas mixing unit and is used to catalytically convert the syngas into methanol. In addition, the system is equipped with a control device, which establishes signal connections with the alkaline electrolysis hydrogen production unit, the solid oxide electrolysis cell unit, and the pressure swing adsorption unit, respectively, to coordinate the operation of the entire system.

[0024] Meanwhile, the system's control logic involves a feedback-based collaborative strategy. First, it instructs the solid oxide electrolyzer to operate at a relatively stable baseline load level to provide a continuous and predictable basic carbon monoxide (CMO) production. Simultaneously, the control unit acquires real-time CMO production signals from the pressure swing adsorption (PSA) unit, directly reflecting the available CMO flow rate. The control unit internally presets a target hydrogen to CMO molar ratio for methanol synthesis. By processing this target value with the real-time CMO production signal, the necessary real-time hydrogen production to achieve the target ratio can be calculated. Subsequently, the control unit dynamically adjusts the hydrogen production power (e.g., input current) of the alkaline electrolysis hydrogen production unit via its signal connection, ensuring that the actual hydrogen production rate precisely matches the calculated demand. This closed-loop control process ultimately ensures that the hydrogen to CMO molar ratio in the syngas output from the syngas mixing unit is stably maintained within the preset target range, thus meeting the stringent requirements for efficient downstream methanol synthesis.

[0025] This application's technical solution integrates an alkaline electrolysis hydrogen production unit, a solid oxide electrolyzer unit, a pressure swing adsorption unit, a syngas mixing unit, a methanol synthesis unit, and a control unit into a single, collaborative system. This solves the problems of inflexible syngas ratio adjustment and complex system structure in traditional solutions. By separating the production paths of the hydrogen and carbon sources, this system achieves decoupled production and flexible allocation of hydrogen and carbon monoxide sources, thus accurately and stably meeting the stringent syngas ratio requirements of methanol synthesis. Simultaneously, in this application's technical solution, the control unit dynamically adjusts the operating power of the alkaline electrolysis hydrogen production unit based on the actual carbon monoxide production signal from the system. This mechanism fully utilizes the difference between the rapid response of alkaline electrolysis hydrogen production and the stable operation of the solid oxide electrolyzer, forming a collaborative control strategy with stable carbon monoxide production as the benchmark and rapidly adjustable hydrogen production as the variable. This not only enables real-time, high-precision control of the syngas ratio but also allows for rapid response to fluctuations in downstream production demand and upstream renewable energy power while maintaining high system efficiency. Furthermore, the technical solution of this application captures unreacted carbon dioxide and returns it to the inlet of the solid oxide electrolysis cell through a pressure swing adsorption device and a circulation pipeline, thus constructing an efficient internal carbon circulation loop. This can improve the overall utilization rate of carbon resources, reduce raw material consumption and carbon emissions, and optimize energy and material utilization efficiency at the system level.

[0026] Based on the technical solutions described above, this specification also provides some specific implementation schemes, which are described below.

[0027] In an optional embodiment, the alkaline electrolysis hydrogen production device includes an electrolyzer, an alkaline circulation system, a gas-liquid separator, and a hydrogen purification system. The solid oxide electrolyzer device includes an SOEC stack, a preheater for preheating the inlet gas, and a heat exchanger integrated with the preheater and / or the SOEC stack. The anode of the SOEC stack is provided with an oxygen outlet. The pressure swing adsorption device includes at least two adsorption towers and a control valve assembly, wherein the control device is configured to control the at least two adsorption towers to alternately perform adsorption and desorption operations. The methanol synthesis apparatus includes a synthesis gas compressor, a methanol synthesis reactor, a separation distillation unit for separating reaction products, and a circulating gas recovery unit for returning unreacted gases to the synthesis gas mixing apparatus.

[0028] Combination Figures 2 to 5 As shown, this embodiment elaborates on the specific composition of each core device of the system. For example... Figure 2 As shown, the alkaline electrolysis hydrogen production device includes an electrolyzer, an alkaline solution circulation system, a gas-liquid separator, and a hydrogen purification system. The electrolyzer is the core equipment for the water electrolysis reaction. The alkaline solution circulation system is responsible for electrolyte delivery and thermal management. The gas-liquid separator separates the hydrogen produced by electrolysis from the alkaline solution, and the hydrogen purification system further removes moisture and impurities from the hydrogen, ultimately outputting high-purity hydrogen. Figure 3 As shown, the solid oxide electrolyzer device includes an SOEC stack, a preheater, and an integrated heat exchanger. The SOEC stack is the core module for achieving high-temperature electrolysis of carbon dioxide, and its anode has a dedicated oxygen outlet. The preheater heats the inlet carbon dioxide gas to near the stack's operating temperature; the integrated heat exchanger effectively recovers the high-temperature waste heat generated by the stack and uses it to preheat the inlet gas, achieving integrated thermal energy within the system and reducing external energy consumption.

[0029] like Figure 4 As shown, the pressure swing adsorption (PSA) device includes at least two adsorption towers and a set of precision control valves. Each adsorption tower is filled with selective adsorbent material. Through programmed control, multiple adsorption towers alternately perform adsorption and desorption operations; that is, while one tower adsorbs and purifies carbon monoxide, another tower desorbs to regenerate the adsorbent and enrich carbon dioxide, thereby achieving continuous and stable gas separation and carbon dioxide recovery. Figure 5 As shown, the methanol synthesis unit includes a syngas compressor, a methanol synthesis reactor, a separation and distillation unit, and a recycle gas recovery unit. The syngas compressor pressurizes the mixed syngas to the pressure required for the reaction; the methanol synthesis reactor converts the syngas into methanol under the action of a catalyst; the separation and distillation unit separates crude methanol from the reaction products through steps such as condensation and distillation, and purifies it to product standards; the recycle gas recovery unit recovers the unreacted syngas and returns it to the inlet of the syngas mixing unit to participate in the reaction again, thereby significantly improving the overall conversion rate and economy of the raw materials.

[0030] In an optional embodiment, the heat exchanger is used to recover the high-temperature waste heat generated during the operation of the solid oxide electrolysis cell device and transfer the recovered heat to the carbon dioxide gas flowing through the preheater to achieve thermal energy integration.

[0031] In this embodiment, the heat exchanger integrated into the solid oxide electrolysis cell device plays a crucial role in energy recovery and reuse. This heat exchanger (e.g., Figure 3 (As shown) Thermal coupling with the high-temperature exhaust side or the stack body of the SOEC fuel cell stack can efficiently capture the high-quality waste heat generated during high-temperature operation of the stack at 600°C to 900°C. This waste heat mainly comes from reversible heat loss, ohmic heat loss, and sensible heat of the exhaust gas from the electrolysis reaction. The heat exchanger is usually designed with highly efficient heat transfer surfaces or channels to ensure that the high-temperature heat is effectively absorbed and transferred by the working medium (such as heat transfer oil, molten salt, or specific gases), thereby converting potentially wasteful heat energy into a usable heat source.

[0032] The recovered heat is specifically used to preheat the carbon dioxide feedstock gas that will enter the SOEC stack for electrolysis. Specifically, the low-temperature carbon dioxide gas flowing through this heat exchanger absorbs the recovered heat carried by the working medium through either indirect or direct contact heat exchange, resulting in a significant temperature increase. The preheated carbon dioxide gas then enters a dedicated preheater (such as...). Figure 3 The final temperature fine-tuning is performed on the front section of the electric heater to achieve the precise temperature required for the fuel cell inlet. This design enables the cascaded utilization and integration of thermal energy within the system, significantly reducing the energy consumption required for external electric heating or fuel heating to heat the feed gas, and directly improving the overall conversion efficiency of electrical energy to chemical energy (CO). It is one of the core components for the system to achieve low-carbon and high-efficiency operation.

[0033] In an optional embodiment, the target value can range from 2.0 to 2.1.

[0034] In an optional embodiment, the control device pre-stores control logic corresponding to four states: system startup, normal operation, standby, and shutdown, and can respond to external signals to coordinate the switching of each device between the above states. Among them, the control logic in the standby state includes controlling the solid oxide electrolytic cell device to maintain a high temperature and perform inert gas purging; The control logic during shutdown includes controlling the methanol synthesis unit to perform passivation treatment on the catalyst.

[0035] In this embodiment, the control device serves as the intelligent central hub of the entire system, pre-stored with a complete and sophisticated multi-state coordinated control program. This program clearly defines four core operating states: system startup, normal operation, standby, and shutdown, and includes all the logical instructions to drive the smooth and orderly switching of each device between different states. The control device continuously monitors external input signals (such as renewable energy power commands from the power grid, downstream methanol demand commands, or manual operation commands) and automatically determines which system state to enter or switch to based on these signals. When a state switch is triggered, the control device synchronously sends coordinated, sequential control commands to the alkaline electrolysis hydrogen production unit, solid oxide electrolysis cell unit, pressure swing adsorption unit, and methanol synthesis unit, ensuring that each unit operates in accordance with preset timing and conditions, thereby achieving a safe and efficient transition of the entire system from one operating mode to another. This logic ensures that the system can flexibly adapt to changes in production plans and intermittent external energy supply.

[0036] For specific non-operating states, the control logic includes equipment protection measures. Specifically, in standby mode, when the system suspends production due to a short-term power outage or reduced demand, one of the control logic instructions is to maintain the solid oxide electrolyzer (SOEC) stack at a high temperature range (e.g., above 600°C) and continuously purge it with an inert gas (such as nitrogen). Maintaining the high temperature prevents significant thermal stress damage to the SOEC stack caused by repeated thermal cycling, while inert gas purging effectively removes active gases (such as CO and O2) from the stack, preventing electrode oxidation under high oxygen partial pressure, thus preparing for a rapid and safe resumption of production. In shutdown mode, when the system needs to be shut down for an extended period, the control logic initiates the catalyst passivation process for the methanol synthesis unit. This process is typically executed after the synthesis gas feed is stopped. The control unit instructs the introduction of a specific passivation gas (such as an inert gas containing a low concentration of oxygen) into the reactor. Under a controlled temperature rise rate, this causes the active components on the catalyst surface within the reactor to slowly and gently oxidize, forming a stable passivation film. This process prevents the catalyst from undergoing severe oxidation or overheating when exposed to air, thus preventing permanent loss of activity. It is a crucial step in protecting precious metal catalysts and ensuring the efficiency of restarting the plant.

[0037] In an optional embodiment, the system may further include: a renewable energy power interface, connected to the power input terminals of the alkaline electrolysis hydrogen production device and the solid oxide electrolysis cell device, for accessing at least one of wind power and photovoltaic power generation.

[0038] In this embodiment, the system further integrates a renewable energy power interface. This interface is a comprehensive power management and distribution unit, functioning to physically and electrically connect with an external power grid or distributed generation network, specifically for receiving at least one type of green electricity from wind power or photovoltaic power generation systems. Internally, this interface typically includes necessary grid connection points, circuit breakers, protective relays, and power regulation modules. Its output is directly connected to the DC or AC power input of the alkaline electrolysis hydrogen production unit and the solid oxide electrolysis cell unit. Through this interface, fluctuating renewable energy power is directly introduced as primary energy to drive the two electrolysis processes, thereby ensuring the low-carbon nature of the methanol production process at its source and making the entire system a link in the "Power-to-X" value chain.

[0039] The design of this renewable energy power interface fully considers the adaptation to and mitigation of input power fluctuations. It is not merely a simple physical connection, but also integrates preliminary power conversion and transient management functions, such as filtering or buffering capabilities to smooth short-term, drastic changes in wind and solar power output. More importantly, this interface works collaboratively with the system's control device at the signal level. The control device can acquire real-time parameters such as power and voltage input through this interface and use them as key collaborative control input variables. Based on this, the control device can dynamically optimize the load distribution between the alkaline electrolysis hydrogen production unit and the solid oxide electrolyzer unit. For example, it can increase total capacity when renewable energy power is abundant and guide the system into standby mode when power is insufficient, thereby maximizing the proportion of green electricity consumption and ensuring stable and economical system operation under high-proportion fluctuating renewable energy access. Ultimately, it achieves flexible coupling between chemical production and renewable energy power generation at both the time and power levels.

[0040] Meanwhile, this application also provides a method for syngas preparation and methanol synthesis using the system described in any of the preceding claims, comprising the following steps: (1) Start-up stage: control the solid oxide electrolysis cell device to heat up to the operating temperature and power it on to start the pressure swing adsorption device; after the pressure swing adsorption device outputs a stable carbon monoxide gas flow, start the alkaline electrolysis hydrogen production device and adjust its hydrogen production rate so that the mixed syngas reaches the target molar ratio.

[0041] (2) Normal operation phase: The solid oxide electrolysis cell device is maintained at the reference load, and the hydrogen production rate of the alkaline electrolysis hydrogen production device is dynamically adjusted based on the real-time output carbon monoxide flow rate of the pressure swing adsorption device in order to maintain the target molar ratio.

[0042] (3) Standby stage: Stop supplying power to the solid oxide electrolysis cell device and the alkaline electrolysis hydrogen production device, but maintain the high temperature of the solid oxide electrolysis cell device and perform inert gas purging, while stopping the adsorption-desorption cycle of the pressure swing adsorption device.

[0043] (4) Shutdown phase: sequentially reduce and stop the operating load of each device; control the methanol synthesis device to stop feeding, cool down and depressurize and passivate the catalyst; control the solid oxide electrolysis cell device to perform a slow cooling program.

[0044] The above content is elaborated below. In the technical solution of this application, the start-up phase of the syngas preparation and methanol synthesis methods adopts a step-by-step coordinated strategy, aiming to establish the entire process safely and smoothly. This phase begins with the most time-consuming step, namely, controlling the solid oxide electrolyzer device to slowly heat from ambient temperature to its operating temperature (600℃-900℃) according to the set heating rate to avoid thermal stress damage. At the same time, the preheating program of the alkaline electrolysis hydrogen production device is started in parallel, including starting its alkaline circulation pump and temperature control system, so that the electrolyte quickly reaches the optimal operating temperature range, preparing for rapid hydrogen production. The methanol synthesis device also begins reactor preheating and system pressurization. After the SOEC reaches the set temperature, the second start-up phase begins, that is, the controller instructs the SOEC to be energized to its preset reference temperature (…). I The SOEC (Solar Electrolysis Processing Unit) begins electrolysis to produce gas. Simultaneously, the Pressure Swing Adsorption (PSA) unit is started to receive the mixed tail gas containing CO and CO2 from the SOEC, establishing a cycle for adsorption, purification, and the return of enriched CO2 to the SOEC inlet. The controller continuously monitors the carbon monoxide flow rate at the first outlet of the PSA unit. Once the output stabilizes, the preheated alkaline electrolysis hydrogen production unit is quickly started, and its input current is dynamically adjusted. I ~AE~), after mixing its hydrogen production with a stable CO flow rate, immediately achieves the target hydrogen / carbon monoxide molar ratio (e.g., 2.0-2.1) required for methanol synthesis, thereby completing system startup and smoothly transitioning to normal operation.

[0045] During normal operation, standby, and shutdown phases, this scheme implements differentiated collaborative control based on different objectives. In normal operation, the core objective is to maintain the SOEC unit's efficient and stable carbon monoxide production at baseline load. Simultaneously, the alkaline electrolysis hydrogen production unit serves as the sole rapid adjustment unit. The controller dynamically matches the hydrogen production rate by rapidly adjusting I~AE~ based on real-time carbon monoxide flow data obtained from the pressure swing adsorption (PSA) unit, thereby precisely maintaining the syngas ratio. When encountering renewable energy power shortages or temporary demand declines, the system enters a standby (idling) phase. The controller stops supplying power to the SOEC and AE units, but instructs the SOEC unit to maintain a high temperature and undergo inert gas purging to preserve its thermal state and protect the stack. Simultaneously, the PSA unit stops its adsorption-desorption cycle, and the methanol unit maintains temperature and pressure to create conditions for rapid recovery. When a long-term shutdown is required, a shutdown phase is implemented. First, the controller slowly and synchronously reduces the operating load of the SOEC and AE units. Then, the methanol synthesis unit stops feeding, gradually cools and depressurizes, and passivates the catalyst to prevent deactivation. Subsequently, the SOEC unit enters a controlled, slow cooling process after power failure; the AE unit is completely powered off and its cycle stops; the pressure swing adsorption unit stops operating and the system is depressurized. This series of orderly steps ensures the safety and integrity of each unit, especially the high-temperature SOEC and valuable catalysts, during the state transition process.

[0046] In an optional embodiment, during the normal operation phase, the hydrogen production rate of the alkaline electrolysis hydrogen production device is dynamically adjusted by rapidly regulating the input current of the device.

[0047] During the normal operation of the system in this embodiment, the core execution mechanism for dynamically adjusting the syngas ratio lies in the rapid and precise adjustment of the input current of the alkaline electrolysis hydrogen production unit. Under a given electrolyte temperature and pressure, the hydrogen production rate (molar flow rate) of this unit is directly and rapidly linearly proportional to the magnitude of the DC current flowing into the electrolyzer, a relationship that follows Faraday's law of electrolysis. Based on the real-time acquired carbon monoxide production signal and the preset target molar ratio, the control device calculates the required instantaneous hydrogen production and converts this demand value into a corresponding target current setpoint. Subsequently, the control device, through its signal connection, sends commands to the power system of the alkaline electrolysis hydrogen production unit (such as a high-power DC power supply or a thyristor rectifier) ​​to directly adjust its output current. This current adjustment process does not require changes to the reactor's temperature, pressure, or other large-inertia thermal parameters, thus possessing a rapid response capability at the millisecond to second level. It is the most direct and effective means of achieving real-time closed-loop control of the syngas ratio.

[0048] The speed and precision of the current regulation are fundamental to achieving the coordinated control strategy. For example... Figure 2As shown, a high-speed data link exists between the control device and the power supply unit of the alkaline electrolysis hydrogen production unit. When the upstream CO production or the downstream H2 demand changes, the control algorithm can calculate and issue a new current setpoint in a very short time. After receiving the command, the power supply system uses its internal fast power semiconductor devices (such as IGBTs) to perform chopping or phase-shifting control, achieving stepless, smooth, and highly dynamic adjustment of the output current. This adjustment is not only fast-responding but also highly accurate, stabilizing the hydrogen production rate near the calculated theoretical value, thereby ensuring that the H2 / CO molar ratio of the mixed syngas is strictly controlled within a narrow target range, such as 2.0-2.1. It is through this method of using current as a direct control variable that the alkaline electrolysis hydrogen production unit can fully leverage its fast-response characteristics and perfectly play the role of a flexible system regulator.

[0049] Meanwhile, this application also provides a method for the coordinated control of a syngas production and methanol synthesis system, the method including: The solid oxide electrolyzer is set to operate at a stable reference load as a reference source for the system's carbon monoxide supply. The alkaline electrolysis hydrogen production unit is configured as a unit with a rapidly adjustable hydrogen production rate; Real-time acquisition of signals reflecting the actual carbon monoxide production of the system; The required real-time hydrogen production is calculated based on the preset target molar ratio of hydrogen to carbon monoxide and the actual carbon monoxide production signal. By rapidly adjusting the operating power of the alkaline electrolysis hydrogen production device, its actual hydrogen production rate is matched with the required real-time hydrogen output, thereby achieving dynamic closed-loop control of the syngas ratio.

[0050] The core of the collaborative control method provided in this application lies in establishing a dynamic adjustment mechanism based on differences in device characteristics and real-time feedback. This method first sets the functions of the system: [e.g., solid oxide electrolysis cell device...] Figure 2 The system (as shown) is continuously operated under a pre-optimized, stable baseline load with minimal fluctuations, serving as a stable source of carbon monoxide for the system, outputting a continuous and predictable gas flow of carbon monoxide. Simultaneously, the alkaline electrolysis hydrogen production unit (such as...) is... Figure 2 (As shown) is clearly configured as a flexible unit with a rapidly adjustable hydrogen production rate within the system. To implement closed-loop control, this method uses integrated system measuring instruments to acquire accurate signals reflecting the actual carbon monoxide production of the system in real time. This crucial signal originates directly from the pressure swing adsorption (PSA) device (such as...) that performs online purification and metering of the gas produced by the solid oxide electrolyzer. Figure 4The product gas outlet pipeline (as shown) ensures that the obtained data directly corresponds to the effective gas flow rate that will participate in the synthesis, providing real and continuous feedback information for the entire control loop.

[0051] After receiving the real-time carbon monoxide production signal, the control process enters the core calculation and execution phase. The control unit pre-stores the target molar ratio of hydrogen to carbon monoxide required for the methanol synthesis reaction. Based on this target ratio and the real-time monitored carbon monoxide flow rate, the control logic dynamically calculates the real-time hydrogen demand necessary to meet this ratio. Then, the core execution action of the method is activated: by rapidly adjusting the operating power of the alkaline electrolysis hydrogen production device (specifically, by precisely adjusting its input current at the millisecond to second level), the hydrogen production rate is instantly changed. Utilizing the inherent rapid electrochemical response characteristics of the alkaline electrolysis process, the actual hydrogen production rate can be quickly and accurately adjusted to match the aforementioned calculated hydrogen demand. This "monitoring-calculation-adjustment" process, from signal sensing and demand calculation to power execution, operates continuously in a loop, thus forming a highly efficient dynamic closed-loop control circuit. Ultimately, it achieves real-time, high-precision, and stable control of the ratio of hydrogen to carbon monoxide in the syngas, effectively compensating for the slow response of solid oxide electrolyzers due to their large thermal inertia, and ensuring that the downstream methanol synthesis process always proceeds efficiently and stably under optimized gas composition conditions.

[0052] In an optional embodiment, the signal reflecting the actual carbon monoxide production comes from a pressure swing adsorption device that purifies and measures the flow rate of the gas produced by the solid oxide electrolysis cell.

[0053] In this embodiment, the actual carbon monoxide production signal relied upon by the system for closed-loop control is directly and reliably sourced from the pressure swing adsorption (PSA) device. For example... Figure 4 As shown, this device, serving as the processing unit for the gas produced by the solid oxide electrolysis cell, has one of its core functions: online purification and flow metering of the mixed gas containing CO and CO2. Specifically, a high-precision gas flow meter (such as a mass flow meter) is integrated into the first outlet pipeline of the pressure swing adsorption unit (i.e., the purified carbon monoxide product gas output pipeline). This flow meter can continuously measure and output the instantaneous volume or mass flow rate of carbon monoxide in real time. The control device directly acquires the reading of this flow meter via a signal line, and this reading is defined as the authoritative electrical signal of the system's current "actual carbon monoxide production." This design ensures that the CO production data acquired by the control device is not an indirect estimate, but rather the actual gas flow rate after actual separation and purification, which is about to participate in the synthesis reaction, thus guaranteeing the accuracy and representativeness of the feedback signal from the source.

[0054] The generation and transmission of this signal form the sensing foundation of the entire collaborative control strategy. The pressure swing adsorption (PSA) unit, through the alternating operation of multiple adsorption towers, achieves a continuous and stable output of carbon monoxide, enabling the flow meter to measure a highly reliable flow signal with minimal fluctuations. The control device rapidly calculates this real-time flow signal against the internally preset target hydrogen / carbon monoxide molar ratio, thus accurately determining the instantaneous hydrogen production required to achieve the target ratio. Therefore, the PSA unit plays a crucial "sensor" role here; it is not only a material separation device but also a measurement unit providing key process parameters. Downstream adjustments based on this real and continuous production signal allow the entire system to overcome the bottleneck of slow response in SOEC units, achieving dynamic, high-precision, and stable control of the syngas ratio.

[0055] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of one embodiment, and the modules or processes shown in the drawings are not necessarily essential for implementing the present invention.

[0056] Those skilled in the art will understand that the modules in the apparatus of the embodiments can be distributed in the apparatus of the embodiments as described in the embodiments, or they can be located in one or more devices different from this embodiment with corresponding changes. The modules of the above embodiments can be combined into one module, or they can be further divided into multiple sub-modules.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A syngas preparation and methanol synthesis system based on the synergistic operation of an alkaline tank and SOEC, characterized in that, include: Alkaline electrolysis hydrogen production unit, used for producing hydrogen by electrolyzing water; A solid oxide electrolytic cell device for producing carbon monoxide by electrolyzing carbon dioxide; The pressure swing adsorption device has its inlet in fluid communication with the mixed gas outlet of the solid oxide electrolysis cell device, and is used to purify the mixed gas so as to output purified carbon monoxide from its first outlet and enriched carbon dioxide from its second outlet. The second outlet of the pressure swing adsorption device is in fluid communication with the carbon dioxide inlet of the solid oxide electrolysis cell device to form a carbon dioxide circulation loop. The syngas mixing device is fluidly connected to the hydrogen outlet of the alkaline electrolysis hydrogen production device and the first outlet of the pressure swing adsorption device, respectively, and is used to mix hydrogen and carbon monoxide to form syngas. A methanol synthesis unit is fluidly connected to the syngas outlet of the syngas mixing unit and is used to catalytically synthesize methanol from the syngas. The control device is connected to the alkaline electrolysis hydrogen production device, the solid oxide electrolysis cell device and the pressure swing adsorption device respectively; The control device is configured to: control the operating load of the solid oxide electrolysis cell device at a reference level, and dynamically adjust the hydrogen production power of the alkaline electrolysis hydrogen production device based on the carbon monoxide production signal from the pressure swing adsorption device, so as to maintain the molar ratio of hydrogen to carbon monoxide in the syngas output by the syngas mixing device within a preset target value range.

2. The syngas preparation and methanol synthesis system based on the synergistic operation of an alkali tank and SOEC as described in claim 1, characterized in that: The alkaline electrolysis hydrogen production device includes an electrolytic cell, an alkaline circulation system, a gas-liquid separator, and a hydrogen purification system. The solid oxide electrolyzer device includes an SOEC stack, a preheater for preheating the inlet gas, and a heat exchanger integrated with the preheater and / or the SOEC stack. The anode of the SOEC stack is provided with an oxygen outlet. The pressure swing adsorption device includes at least two adsorption towers and a control valve assembly, wherein the control device is configured to control the at least two adsorption towers to alternately perform adsorption and desorption operations. The methanol synthesis apparatus includes a synthesis gas compressor, a methanol synthesis reactor, a separation distillation unit for separating reaction products, and a circulating gas recovery unit for returning unreacted gases to the synthesis gas mixing apparatus.

3. The syngas preparation and methanol synthesis system based on the synergistic operation of an alkali tank and SOEC as described in claim 2, characterized in that: The heat exchanger is used to recover the high-temperature waste heat generated during the operation of the solid oxide electrolysis cell device and transfer the recovered heat to the carbon dioxide gas flowing through the preheater to achieve thermal energy integration.

4. The syngas preparation and methanol synthesis system based on the synergistic operation of an alkali tank and SOEC as described in claim 1, characterized in that: The target value ranges from 2.0 to 2.

1.

5. The syngas preparation and methanol synthesis system based on the synergistic operation of an alkali tank and SOEC according to claim 1, characterized in that: The control device has pre-stored control logic corresponding to four states: system startup, normal operation, standby, and shutdown, and can respond to external signals to coordinate the switching of each device between the above states. Among them, the control logic in the standby state includes controlling the solid oxide electrolytic cell device to maintain a high temperature and perform inert gas purging; The control logic during shutdown includes controlling the methanol synthesis unit to perform passivation treatment on the catalyst.

6. The syngas preparation and methanol synthesis system based on the synergistic operation of an alkali tank and SOEC according to claim 1, characterized in that, Also includes: A renewable energy power interface is connected to the power input terminals of the alkaline electrolysis hydrogen production device and the solid oxide electrolysis cell device, and is used to connect to at least one of wind power and photovoltaic power generation.

7. A method for syngas preparation and methanol synthesis using the system described in any one of claims 1 to 6, characterized in that, Includes the following steps: Start-up phase: Control the solid oxide electrolysis cell device to heat up to the operating temperature and power it on to start the pressure swing adsorption device; After the pressure swing adsorption device outputs a stable carbon monoxide gas flow, the alkaline electrolysis hydrogen production device is started and its hydrogen production rate is adjusted so that the mixed syngas reaches the target molar ratio. Normal operation phase: The solid oxide electrolysis cell device is maintained at the reference load, and the hydrogen production rate of the alkaline electrolysis hydrogen production device is dynamically adjusted based on the real-time carbon monoxide flow rate output by the pressure swing adsorption device in order to maintain the target molar ratio; Standby phase: Power supply to the solid oxide electrolysis cell device and the alkaline electrolysis hydrogen production device is stopped, but the high temperature of the solid oxide electrolysis cell device is maintained and inert gas purging is performed, while the adsorption-desorption cycle of the pressure swing adsorption device is stopped. Shutdown phase: Sequentially reduce and stop the operating load of each unit; control the methanol synthesis unit to stop feeding, cool and depressurize, and passivate the catalyst; control the solid oxide electrolysis cell unit to execute a slow cooling program.

8. The method for preparing syngas and synthesizing methanol according to claim 7, characterized in that, During the normal operation phase, the hydrogen production rate of the alkaline electrolysis hydrogen production device is dynamically adjusted by rapidly regulating the input current of the device.

9. A method for coordinated control of a syngas preparation and methanol synthesis system, characterized in that, The method includes: The solid oxide electrolyzer is set to operate at a stable reference load as a reference source for the system's carbon monoxide supply. The alkaline electrolysis hydrogen production unit is configured as a unit with a rapidly adjustable hydrogen production rate; Real-time acquisition of signals reflecting the actual carbon monoxide production of the system; The required real-time hydrogen production is calculated based on the preset target molar ratio of hydrogen to carbon monoxide and the actual carbon monoxide production signal. By rapidly adjusting the operating power of the alkaline electrolysis hydrogen production device, its actual hydrogen production rate is matched with the required real-time hydrogen output, thereby achieving dynamic closed-loop control of the syngas ratio.

10. The cooperative control method according to claim 9, characterized in that, The signal reflecting the actual carbon monoxide production comes from the pressure swing adsorption device, which purifies and measures the flow rate of the gas produced by the solid oxide electrolysis cell.

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