SOEC-coupled solar hydrogen, oxygen and salt production system and operation method

Abstract

The invention discloses an SOEC-coupled solar hydrogen, oxygen and salt production system and an operation method, which realize comprehensive and efficient utilization of renewable energy sources and seawater resources and are free of pollutant emission in the whole process. The system is composed of a solar photovoltaic power generation system, a solar seawater distillation system and a solid oxide electrolytic cell SOEC gas production system, wherein the solar photovoltaic power generation system supplies power to the system. The solar seawater distillation system is responsible for raw material pretreatment, after seawater is pumped and filtered by a pump body, one part of seawater is sent into an evaporator to be exposed to the sun to prepare crude salt, and the other part is used for cooling a condenser; meanwhile, the solar air heating system heats air, water vapor in the evaporator is brought into the condenser to be liquefied, and produced distilled water serves as an SOEC gas making raw material. Distilled water is preheated by the multi-stage heat regenerator and heated by the electric heater to a working temperature, and then is fed into the SOEC cathode for electrolysis. The anode generates oxygen; and cooling, separating, drying and compressing the hydrogen-water mixed gas generated by the cathode, and storing for later use. And synchronous production of hydrogen production, oxygen production and salt production is realized.

Description

Technical Field

[0001] This invention belongs to the field of seawater utilization and SOEC electrolysis for hydrogen production technology, specifically relating to a solar-powered seawater electrolysis system coupled with SOEC for hydrogen, oxygen, and salt production, and its operation method. Background Technology

[0002] Driven by both global energy transition and water scarcity, the comprehensive utilization of seawater, as an abundant renewable resource, in areas such as hydrogen production, salt production, and freshwater acquisition has become a research hotspot in the industry. Currently, seawater desalination, seawater salt production, and water electrolysis for hydrogen / oxygen production are mostly independent, single-process operations. Seawater desalination consumes a large amount of energy, seawater salt production has a long cycle, and the low-temperature electrolysis technology used in water electrolysis is inefficient. These three processes operate independently, producing only a single product, resulting in low overall resource utilization efficiency. Summary of the Invention

[0003] The purpose of this invention is to provide a solar-powered hydrogen, oxygen, and salt production system coupled with SOEC and its operation method, in order to solve the technical problems of low electrolysis efficiency and insufficient resource utilization in traditional technologies.

[0004] To achieve the above objectives, the present invention employs the following technical solution: A solar-powered hydrogen, oxygen, and salt production system coupled with SOEC includes a solar photovoltaic power generation system, a solar seawater distillation system, and a solid oxide electrolyzer (SOEC) gas production system. The solar photovoltaic power generation system includes a solar cell array 1, a battery 2, and a rectifier 3. The solar cell array 1 prioritizes power supply to other electrical devices in the system and charges the battery 2 when its power generation capacity is sufficient. The battery 2 can supply power to other devices in the system when the power supply capacity of the solar cell array 1 is insufficient. The rectifier 3 draws power from the power grid to the system when the power supply inside the system is insufficient. The solar-powered seawater distillation system includes a solar evaporator 4, a seawater condenser 5, a blower 6, an air heater 7, a solar water heater circulation pump 8, a solar water heater collector 9, a seawater pump 10, a seawater filter 11, and a feed water pump 12. The seawater pump 10 draws seawater and sends it to the seawater filter 11 to remove large particles. Part of the filtered seawater is sent to the solar evaporator 4, where it is evaporated under sunlight to obtain coarse salt. The other part is sent to the seawater condenser 5, where it cools the hot air and is then discharged back into the sea. The air heater 7, the solar water heater circulation pump 8, and the solar water heater collector 9 form a solar air heating system. The solar water heater circulation pump 8 sends cold water to the solar water heater collector 9 for heating before it enters the air heater 7. The blower 6 sends dry, cold air into the air heater 7, where it is heated and then enters the solar evaporator 4, carrying its internal water vapor into the seawater condenser 5. The condensed water vapor flows into the feed water pump 12 and is then sent to the SOEC gasification system. The SOEC gasification system includes an electric heater 13, an SOEC 14, an anode regenerator 15, an oxygen compressor 16, an oxygen compressor cooler 17, an oxygen storage tank 18, an oxygen tank outlet valve 19, a first cathode regenerator 20, a second cathode regenerator 21, an anode condenser 22, a gas-liquid separator 23, a gas dryer 24, a hydrogen compressor 25, a hydrogen compressor cooler 26, a hydrogen storage tank 27, a hydrogen tank outlet valve 28, a hydrogen-water mixing valve 29, a water storage tank 30, and pipelines connecting the various devices. Condensate is pumped by a water pump 12 to the second cathode regenerator 21 and heated to boiling. The resulting water vapor mixes with hydrogen at the hydrogen-water mixing valve 29, is further heated in the first cathode regenerator 20, and then enters the electric heater 13 to be heated to the electrolysis operating temperature before finally being sent to the SOEC. Electrolysis is performed at the cathode 14. The hydrogen and water vapor mixture obtained from electrolysis are successively sent to the first cathode regenerator 20 and the second cathode regenerator 21 for cooling. Then, it enters the anode condenser 22, where seawater is used to condense the water vapor into liquid water. The liquid water is then sent to the gas-liquid separator 23 to separate the water and hydrogen. The liquid water is directly stored in the water storage tank 30. The hydrogen passes through the gas dryer 24 to remove residual moisture, the hydrogen compressor 25 for compression, and the hydrogen compressor cooler 26 for cooling. Finally, it is stored in the hydrogen storage tank 27. On the anode side, the electric heater 13, SOEC 14, anode regenerator 15, oxygen compressor 16, oxygen compressor cooler 17, oxygen storage tank 18, and oxygen tank outlet valve 19 form a closed-loop oxygen circulation. Excess oxygen produced by electrolysis is stored and extracted in the oxygen storage tank 18.

[0005] The electric heater 13 has two independent gas channels, with outlets connected to the anode and cathode of the SOEC 14, respectively. Independent channels prevent gas mixing, and the same heater ensures that the anode and cathode gases are at the same temperature, reducing the temperature difference within the fuel cell stack.

[0006] Hydrogen for electrode protection is supplied by hydrogen storage tank 27, with flow controlled by hydrogen tank outlet valve 28. It sequentially enters the cold fluid channel of hydrogen compressor cooler 26, hydrogen-water mixing valve 29, the cold fluid channel of cathode first regenerator 20, and the cathode channel of electric heater 13, finally entering SOEC cathode 14 for electrolysis. This fully utilizes the heat generated during the process to heat the gas, reducing the additional heat required by electric heater 13 and improving the overall energy efficiency of the system.

[0007] The operation method of the solar-powered hydrogen, oxygen, and salt production system coupled with SOEC is as follows: When there is sufficient sunlight, the electricity generated by the solar cell array 1 is given priority to supply the various electrical devices in the system, and the surplus electricity is stored in the battery 2; when there is insufficient sunlight, the power generated by the solar cell array 1 is insufficient to supply the power of the system, and the electricity stored in the battery 2 is used first to fill the power supply gap; after the electricity stored in the battery 2 is exhausted, the system draws electricity from the grid through the rectifier 3. The seawater pump 10 pumps seawater to the seawater filter 11 and injects it into the evaporation tank of the solar evaporator 4 until the highest liquid level is reached, then stops the water injection; the solar air heating system consisting of the air heater 7, the solar water heater circulation pump 8, and the solar water heater collector 9 and the air circulation blowing system consisting of the seawater condenser 5, the blower 6, and the air heater 7 are turned on; the water vapor in the solar evaporator 4 is blown out using dry hot air, cooled and liquefied in the seawater condenser 5 to obtain distilled water, which is then sent to the solid oxide electrolysis cell SOEC gasification system by the feed water pump 12; When the SOEC electrolysis unit is operating, the oxygen tank outlet valve 19 is opened. Oxygen is preheated by the oxygen compressor cooler 17 and the anode regenerator 15, and then heated to the SOEC operating temperature by the electric heater 13 before being sent to the stack anode. To ensure smooth system operation, the oxygen storage tank 18 needs to maintain a preset oxygen pressure. During the initial startup, a preset amount of oxygen needs to be added to the oxygen storage tank. Water from the feedwater pump 12 is heated and vaporized in the cathode second regenerator 21. The resulting water vapor enters the hydrogen-water mixing valve 29 to mix with hydrogen, is further heated in the cathode first regenerator 20, and finally heated to the SOEC operating temperature by the electric heater 13 before being sent to the stack cathode. To ensure smooth system operation, the hydrogen storage tank 27 needs to maintain a preset hydrogen pressure. During the initial startup, a preset amount of hydrogen needs to be added to the tank. The amount of hydrogen added should ensure that the pressure in the hydrogen storage tank 27 is not lower than the minimum safe pressure before receiving electrolytic hydrogen replenishment.

[0008] Compared with the prior art, the present invention has the following advantages: 1. This invention combines seawater desalination, seawater salt production, and water electrolysis for oxygen and hydrogen production, thereby achieving full utilization of seawater.

[0009] 2. The energy required for system operation is provided by solar energy, which complies with green industry policies and does not generate carbon emissions.

[0010] 3. By utilizing heat exchangers to recover heat, multi-stage heat utilization is achieved, improving system efficiency. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a solar-powered seawater electrolysis system coupled with SOEC for hydrogen, oxygen, and salt production, as proposed in this invention. Detailed Implementation

[0012] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0013] like Figure 1 As shown, the present invention proposes a solar-powered hydrogen, oxygen, and salt production system coupled with SOEC, comprising a solar photovoltaic power generation system, a solar seawater distillation system, and a solid oxide electrolyzer (SOEC) gas production system.

[0014] The solar photovoltaic power generation system includes a solar cell array 1, a battery 2, and a rectifier 3, all of which are directly connected to electrical appliances. The solar cell array 1 is connected to the battery 2, allowing excess power to be used to charge the battery 2. The rectifier 3 is connected to the power grid and can serve as a backup power source for the system.

[0015] The solar-powered seawater distillation system comprises a solar evaporator 4, a seawater condenser 5, a blower 6, an air heater 7, a solar water heater circulation pump 8, a solar water heater collector 9, a seawater pump 10, a seawater filter 11, and a feed water pump 12. During system operation, the seawater pump 10 first pumps seawater into the seawater filter 11 to remove impurities and particulate matter, and then divides it into three streams entering the system. The first stream enters the bottom of the solar evaporator 4, where it evaporates under the combined action of sunlight and hot air flow, leaving coarse salt at the bottom. The second and third streams enter the seawater condenser 5 and the anode condenser 22 respectively as cooling liquid, and are then discharged. The solar evaporator 4, seawater condenser 5, blower 6, and air heater 7 are sequentially connected, forming a water vapor evaporation-condensation cycle using air as the working fluid. The air is heated to above 40°C in the air heater 7 and enters the upper layer of the solar evaporator 4, where the humid air rich in water vapor is blown out and enters the seawater condenser 5. The low-temperature seawater lowers the air temperature, causing the moisture in the air to condense. The resulting condensate is sent to the SOEC gasification system in the solid oxide electrolysis cell. Air heater 7, solar water heater circulation pump 8, and solar water heater collector 9 are connected in sequence to form a solar air heating cycle with water as the working fluid.

[0016] The solid oxide electrolyzer (SOEC) gasification system includes an electric heater 13, an SOEC 14, an anode regenerator 15, an oxygen compressor 16, an oxygen compressor cooler 17, an oxygen storage tank 18, an oxygen tank outlet valve 19, a first cathode regenerator 20, a second cathode regenerator 21, an anode condenser 22, a gas-water separator 23, a gas dryer 24, a hydrogen compressor 25, a hydrogen compressor cooler 26, a hydrogen storage tank 27, a hydrogen tank outlet valve 28, a hydrogen-water mixing valve 29, and a water storage tank 30. The electric heater 13 and the SOEC 14 are connected to a solar photovoltaic power generation system via cables. The electric heater 13 has two independent gas channels, with outlets connected to the anode and cathode of the SOEC 14, respectively. The outlets of the SOEC 14 anode and cathode are connected to the hot fluid inlets of the anode regenerator 15 and the first cathode regenerator 20, respectively, to recover heat from the working fluid. The hot fluid outlet of the anode regenerator 15 is connected to the oxygen compressor 16. The outlet of the oxygen compressor 16 is sequentially connected to the hot fluid channel of the oxygen compressor cooler 17 and the oxygen storage tank 18. The outlet of the oxygen storage tank 18 is connected to the oxygen tank outlet valve 19, and sequentially connected to the cold fluid channel of the compressor cooler 17, the cold fluid channel of the anode regenerator 15, and the anode channel of the electric heater 13. The hot fluid outlet of the cathode first regenerator 20 is sequentially connected to the hot fluid channel of the cathode second regenerator 21, the hot fluid channel of the anode condenser 22, and the gas-liquid separator 23. The lower liquid outlet of the gas-liquid separator 23 is connected to the water storage tank 30, and the upper gas outlet is connected to the gas dryer 24. The dried hydrogen sequentially enters the hot fluid channel of the hydrogen compressor 25 and the hydrogen compressor cooler 26, and finally enters the hydrogen storage tank 27 for storage. Hydrogen for protecting the electrodes is supplied by hydrogen storage tank 27. The flow rate is controlled by hydrogen tank outlet valve 28. The hydrogen enters the cold fluid channel of hydrogen compressor cooler 26, hydrogen-water mixing valve 29, cold fluid channel of cathode first regenerator 20, and cathode channel of electric heater 13 in sequence, and finally enters SOEC14 cathode for electrolysis.

Claims

1. A solar-powered hydrogen, oxygen, and salt production system coupled with SOEC, characterized in that: This includes solar photovoltaic power generation systems, solar seawater distillation systems, and solid oxide electrolysis (SOEC) gasification systems. The solar-powered seawater distillation system includes a solar evaporator (4), a seawater condenser (5), a blower (6), an air heater (7), a solar water heater circulation pump (8), a solar water heater collector (9), a seawater pump (10), a seawater filter (11), and a feed pump (12). The seawater pump (10) draws seawater and sends it to the seawater filter (11) to remove large particles of impurities. Part of the filtered seawater is sent to the solar evaporator (4) and evaporated by sunlight to obtain crude salt products. The other part is sent to the seawater condenser (5) to cool the hot water. The air is discharged back into the sea; the air heater (7), the solar water heater circulation pump (8) and the solar water heater collector (9) form a solar air heating system. The solar water heater circulation pump (8) sends cold water to the solar water heater collector (9) and heats it before it enters the air heater (7); the blower (6) sends dry and cold air into the air heater (7), and after heating, it enters the solar evaporator (4) and carries the water vapor inside into the seawater condenser (5); after the water vapor condenses, it flows into the feed water pump (12) and is sent to the SOEC gasification system of the solid oxide electrolysis cell; The SOEC gasification system of the solid oxide electrolyzer includes an electric heater (13), SOEC (14), an anode regenerator (15), an oxygen compressor (16), an oxygen compressor cooler (17), an oxygen storage tank (18), an oxygen tank outlet valve (19), a cathode first regenerator (20), a cathode second regenerator (21), an anode condenser (22), a gas-water separator (23), a gas dryer (24), a hydrogen compressor (25), a hydrogen compressor cooler (26), a hydrogen storage tank (27), a hydrogen tank outlet valve (28), a hydrogen-water mixing valve (29), a water storage tank (30), and pipelines connecting the various devices. The condensate is pumped by a water pump (12) to the cathode second regenerator (21) and heated to boiling. The resulting water vapor is mixed with hydrogen at the hydrogen-water mixing valve (29), and after further heating in the cathode first regenerator (20), it enters the electric heater (13) for heating to start electrolysis. The temperature is finally sent to the SOEC (14) cathode for electrolysis; the hydrogen and water vapor mixture obtained by electrolysis are successively sent to the first cathode regenerator (20) and the second cathode regenerator (21) for cooling, and then enter the anode condenser (22) to condense the water vapor into liquid water using seawater, and then send it to the gas-water separator (23) to separate water and hydrogen; the liquid water is directly stored in the water storage tank (30), and the hydrogen passes through the gas dryer (24) to remove the remaining water, the hydrogen compressor (25) for compression, the hydrogen compressor cooler (26) for cooling, and finally stored in the hydrogen storage tank (27); the anode side is formed by the electric heater (13), SOEC (14), anode regenerator (15), oxygen compressor (16), oxygen compressor cooler (17), oxygen storage tank (18) and oxygen tank outlet valve (19) to form a closed-loop oxygen cycle, and the excess oxygen produced by electrolysis is stored and extracted in the oxygen storage tank (18).

2. The solar-powered hydrogen, oxygen, and salt production system coupled with SOEC according to claim 1, characterized in that, The solar photovoltaic power generation system includes a solar cell array (1), a battery (2) and a rectifier (3); the solar cell array (1) prioritizes power supply to other electrical equipment in the system and charges the battery (2) when the power generation capacity is sufficient. The battery (2) supplies power to other equipment in the system when the power supply capacity of the solar cell array (1) is insufficient. The rectifier (3) calls the power grid to supply power to the system when the power supply inside the system is insufficient.

3. The solar-powered hydrogen, oxygen, and salt production system coupled with SOEC according to claim 1, characterized in that, The electric heater (13) has two independent gas channels, and the outlets are connected to the anode and cathode of SOEC (14) respectively.

4. The solar-powered hydrogen, oxygen, and salt production system coupled with SOEC according to claim 1, characterized in that, Hydrogen for protecting the electrode is supplied by a hydrogen storage tank (27), and the flow rate is controlled by the hydrogen tank outlet valve (28). It enters the cold fluid channel of the hydrogen compressor cooler (26), the hydrogen-water mixing valve (29), the cold fluid channel of the cathode first regenerator (20), the cathode channel of the electric heater (13), and finally enters the SOEC (14) cathode for electrolysis.

5. A method for operating a solar-powered hydrogen, oxygen, and salt production system coupled with SOEC as described in any one of claims 1 to 4, characterized in that, Includes the following steps: When there is sufficient sunlight, the power generated by the solar cell array (1) is given priority to supply the various electrical devices in the system, and the surplus power is put into the storage battery (2); when there is insufficient sunlight, the power generated by the solar cell array (1) is insufficient to supply the power of the system, so the power stored in the storage battery (2) is used to fill the power supply gap; after the power stored in the storage battery (2) is exhausted, the system calls the power of the grid through the rectifier (3); The seawater pump (10) pumps seawater to the seawater filter (11) and injects it into the evaporation tank of the solar evaporator (4) until the highest liquid level is reached, and then stops the water injection; the solar air heating system consisting of the air heater (7), the solar water heater circulation pump (8), and the solar water heater collector (9) and the air circulation blowing system consisting of the seawater condenser (5), the blower (6), and the air heater (7) are turned on; the water vapor in the solar evaporator (4) is blown out by the dry hot air, cooled and liquefied in the seawater condenser (5), and distilled water is obtained and sent to the SOEC gasification system by the feed water pump (12); When the SOEC electrolysis unit is working, the oxygen tank outlet valve (19) is opened. The oxygen is preheated by the oxygen compressor cooler (17) and the anode regenerator (15), and then heated to the SOEC working temperature by the electric heater (13) before being sent to the stack anode. To ensure the smooth operation of the system, the oxygen storage tank (18) needs to maintain a preset oxygen pressure. When starting for the first time, the oxygen storage tank needs to be filled with a preset amount of oxygen. The water from the feed water pump (12) is heated and vaporized in the cathode second regenerator (21). The resulting water vapor enters the hydrogen-water mixing valve (29) to mix with hydrogen. It is further heated in the cathode first regenerator (20) and finally heated to the SOEC working temperature by the electric heater (13) before being sent to the stack cathode. To ensure the smooth operation of the system, the hydrogen storage tank (27) needs to maintain a preset hydrogen pressure. When starting for the first time, the hydrogen storage tank needs to be filled with a preset amount of hydrogen. The amount of hydrogen added should ensure that the pressure of the hydrogen storage tank (27) is not lower than the minimum safe pressure before it receives electrolytic hydrogen replenishment.

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