Low-cost direct carbon solid oxide flame battery for hydrogen production by water electrolysis

Abstract

This invention belongs to the field of solar energy technology, specifically relating to a low-cost direct carbon solid oxide flame battery for hydrogen production via water electrolysis. The direct carbon solid oxide flame battery is an anode-supported type, comprising a cathode side, an electrolyte layer, and an anode side; the electrolyte layer material is yttrium-stabilized zirconium oxide. This invention couples an electrolyzer and a fuel cell, forming a water vapor concentration cell between the anode and cathode. This significantly reduces the dependence of the solid oxide electrolyzer on external electrical energy for hydrogen production via water electrolysis, improving the stability of hydrogen production. Utilizing a fuel-rich flame as the anode fuel gas eliminates the need for external heat source preheating; and the anode tail gas forms a mixture of carbon monoxide, carbon dioxide, and water vapor, which is easily separated for downstream fuel production. This effectively improves battery operating efficiency and reduces the cost of hydrogen production via water electrolysis.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a low-cost direct carbon solid oxide flame battery for hydrogen production by water electrolysis. Background Technology

[0002] Hydrogen production via water electrolysis is key to achieving an energy transition mediated by hydrogen energy and is also the main approach for large-scale hydrogen production in the future. Solid oxide electrolyzers have attracted widespread attention in recent years due to their high hydrogen production efficiency and the ability to generate a large amount of usable waste heat. However, current hydrogen production via water electrolysis using solid oxide electrolyzers still faces challenges such as high production costs, unstable renewable energy supply, and the need for large external heat sources to maintain the anode and cathode of the electrolyzer. Summary of the Invention

[0003] The purpose of this invention is to provide a low-cost direct carbon solid oxide flame battery for hydrogen production by water electrolysis, in order to solve the problems existing in the prior art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a low-cost direct carbon solid oxide flame battery for hydrogen production by water electrolysis, wherein the direct carbon solid oxide flame battery is an anode-supported type, comprising a cathode side, an electrolyte layer, and an anode side; the electrolyte layer material is yttrium-stabilized zirconium oxide;

[0005] The anode side includes an anode layer, a variable-volume anode fuel chamber, and a spring. The spring is connected to the bottom of the variable-volume anode fuel chamber. The anode layer is made of nickel-yttrium-stabilized zirconium oxide.

[0006] The variable-volume anode fuel chamber includes an anode fuel inlet and an anode exhaust gas outlet; the cathode side includes a cathode layer, a cathode gas diffusion layer and a cathode gas flow channel, the bottom of the cathode gas flow channel is connected to the upper part of the cathode gas diffusion layer, the bottom of the cathode gas diffusion layer is connected to the cathode layer, and the cathode layer material is lanthanum strontium manganese ore-yttrium oxide stabilized zirconium oxide.

[0007] Preferably, the cathode side is used as a solid oxide electrolytic cell, where water electrolysis occurs by continuously introducing water vapor into the cathode gas channel; the generated hydrogen and unreacted water vapor are discharged on the cathode side, and oxygen ions pass through the electrolyte layer to reach the anode side.

[0008] Preferably, the anode side is used as a direct carbon solid oxide flame battery. In the variable volume anode fuel chamber, carbon dioxide gas and activated carbon solid react chemically to generate carbon monoxide. Carbon monoxide and oxygen ions react electrochemically to generate carbon dioxide, which provides some electrical energy for the cathode electrolysis of water. In order to maintain the pressure balance between the anode and cathode of the battery, a portion of the mixed gas of carbon monoxide, carbon dioxide and water vapor generated at the anode is discharged from the anode tail gas outlet.

[0009] Preferably, the battery includes two states: normal operation and shutdown feeding.

[0010] In the shutdown and feeding state, first stop the supply of water vapor to the cathode side; open the anode fuel inlet, and the fuel-rich flame generated by the combustion of hydrocarbon fuel mixes with activated carbon near the anode fuel inlet and enters the variable-volume anode fuel chamber until the spring is compressed to its shortest length, then stop feeding and close the anode fuel inlet. In the normal operation state, by continuously supplying water vapor at a temperature of not less than 600°C to the cathode gas flow channel, the battery cathode undergoes the water electrolysis reaction.

[0011] H2O + 2e - =H2+O 2-

[0012] On the anode side, activated carbon containing 5 wt% iron is mixed with a fuel-rich flame in a variable-volume anode fuel chamber, where carbon monoxide electrochemical oxidation and the reverse Boudouard reaction occur. The anode reaction formula is as follows:

[0013] CO+O 2- =CO2 + 2e -

[0014] CO2 + C = 2CO

[0015] As can be seen from the above reaction formula, under normal operating conditions, every 1 mol of activated carbon fuel consumed generates 2 mol of carbon dioxide. In order to maintain the pressure balance between the anode and cathode of the battery, some gas from the anode is discharged from the anode tail gas outlet during operation.

[0016] Preferably, the fuel-rich flame refers to the flame produced when the provided oxidant is less than the stoichiometric value, and the fuel-rich equivalence ratio φ is defined by the following formula:

[0017]

[0018] Preferably, the activated carbon fuel and the fuel-rich flame are mixed before entering the variable-volume anode fuel chamber.

[0019] The beneficial effects of this invention are as follows: This invention introduces a hydrocarbon fuel-rich flame into the anode side of the battery, which can react with the solid carbon fuel at the anode to further produce carbon monoxide required for the electrochemical reaction, and also serve as a heat source for battery startup, eliminating the need for an additional heat source to preheat the anode fuel gas; it utilizes the electrochemical oxidation of carbon monoxide at the anode and the concentration difference of water vapor between the cathode and cathode to provide part of the electrical energy required for cathode activation, reducing dependence on external power supply and improving the stability of water electrolysis; compared to existing flame fuel cells, installing a spring at the bottom of the anode fuel chamber allows for more efficient utilization of activated carbon fuel, and the loading method is simpler; the battery anode exhaust gas separates nitrogen and carbon monoxide / carbon dioxide, facilitating downstream fuel production; it can effectively improve battery operating efficiency and reduce the cost of water electrolysis. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention;

[0021] In the diagram: 1. Cathode gas flow channel; 2. Cathode gas diffusion layer; 3. Cathode layer; 4. Electrolyte layer; 5. Anode layer; 6. Anode fuel chamber with variable volume; 7. Anode fuel inlet; 8. Anode exhaust gas outlet; 9. Spring; 10. Activated carbon; 11. Hydrogen fuel; 12. Activated carbon conveyor belt. Detailed Implementation

[0022] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings and preferred embodiments.

[0023] like Figure 1 As shown, a low-cost direct carbon solid oxide flame battery for hydrogen production by water electrolysis is described. The battery is a Ni-YSZ (nickel-yttrium-stabilized zirconium oxide) / YSZ (yttrium-stabilized zirconium oxide) / LSM-YSZ (lanthanum-strontium-manganese ore-yttrium-stabilized zirconium oxide) anode-supported battery. The battery operates at a temperature of 700–900°C and a pressure of approximately 1.01 atm.

[0024] The battery consists of a cathode side, an electrolyte layer 4, and an anode side.

[0025] The cathode side of the battery includes a cathode gas flow channel 1, a cathode gas diffusion layer 2, and a cathode layer 3; the anode side includes an anode layer 5, a variable-volume anode fuel chamber 6, an anode fuel inlet 7, and an anode exhaust gas outlet 8. The anode side serves as a direct carbon solid oxide flame battery. In the variable-volume anode fuel chamber, carbon dioxide gas and activated carbon solid react chemically to generate carbon monoxide; carbon monoxide and oxygen ions react electrochemically to generate carbon dioxide, providing some electrical energy for the cathode's water electrolysis; to maintain pressure balance between the anode and cathode, a mixture of carbon monoxide, carbon dioxide, and water vapor generated at the anode is discharged from the anode exhaust gas outlet.

[0026] The variable-volume anode fuel chamber 6 is adjusted in volume by a spring 9 installed at the bottom, which changes according to the mass of activated carbon. As the solid activated carbon is continuously consumed, the spring below the anode combustion chamber gradually extends; when the spring extends to its maximum length, the battery needs to be stopped for refueling. When the battery is stopped for refueling, the supply of water vapor to the cathode is first stopped; the anode fuel inlet is opened on the anode side, the activated carbon conveyor belt 12 is started, and activated carbon fuel and a rich-fuel flame are continuously introduced until the spring is compressed to its shortest length, at which point the anode fuel inlet is closed.

[0027] The battery has two states: normal operation and shutdown with refueling.

[0028] In the shutdown and feeding state, first stop the supply of water vapor on the cathode side; open the anode fuel inlet 7, the fuel-rich flame generated by the combustion of hydrocarbon fuel 11 and the activated carbon 10 mix near the anode fuel inlet 7 and enter the variable volume anode fuel chamber 6 until the spring is compressed to its shortest length, stop feeding, and close the anode fuel inlet 7.

[0029] Under normal operating conditions, water vapor at a temperature not lower than 600°C is continuously supplied to the cathode gas flow channel 1, and the battery cathode undergoes the water electrolysis reaction:

[0030] H2O + 2e - =H2+O 2-

[0031] On the anode side, activated carbon containing 5 wt% iron is mixed with a fuel-rich flame in a variable-volume anode fuel chamber 6, where carbon monoxide electrochemical oxidation and the reverse Boudouard reaction occur. The anode reaction formula is as follows:

[0032] CO+O 2- =CO2 + 2e -

[0033] CO2 + C = 2CO

[0034] As can be seen from the above reaction formula, under normal operating conditions, every 1 mol of activated carbon fuel consumed generates 2 mol of carbon dioxide. In order to maintain the pressure balance between the anode and cathode of the battery, some of the gas from the anode is discharged from the anode tail gas outlet 8 during operation.

[0035] Under normal operating conditions, as the activated carbon is continuously consumed, the volume of the anode fuel chamber gradually decreases until the spring is stretched to its maximum length, at which point the battery needs to be stopped for refueling.

[0036] The fuel-rich flame produced by the combustion of hydrocarbon fuels mainly consists of carbon monoxide, carbon dioxide, and water. The fuel-rich flame has a triple function: it directly serves as the start-up heat source for solid oxide fuel cells, forms a water vapor concentration difference between the anode and cathode of the battery, and provides carbon monoxide as the feed gas for the electrochemical reaction at the anode of the battery.

[0037] The battery operating efficiency was improved by adding 5 wt% iron to the activated carbon fuel to promote the reverse Boudouard reaction.

[0038] The fuel-rich flame refers to the flame produced when the oxidant provided is less than the stoichiometric value. The fuel-rich equivalence ratio φ is defined by the following formula:

[0039]

[0040] m fuel and m air These are fuel and air flow rates, respectively. The subscript "act" indicates the actual flow rate, and "static" indicates the flow rate calculated based on the stoichiometric ratio.

[0041] The fuel-rich flame produced by the combustion of hydrocarbon fuel mainly consists of carbon monoxide, carbon dioxide, and water vapor. To provide as much electrical energy as possible for water electrolysis, it is necessary to increase the water vapor concentration difference between the anode and cathode and increase the carbon monoxide content. To ensure that the anode side of the battery can be maintained within the normal operating temperature range during operation, the flame temperature needs to be controlled to prevent it from becoming too low. Therefore, selecting hydrocarbon fuels with higher carbon content and appropriately increasing the fuel-rich equivalence ratio helps to improve battery operating efficiency while ensuring stable and safe operation. For example, when methane is selected as fuel, controlling the fuel-rich equivalence ratio in the range of 1.1 to 1.5 is more appropriate.

[0042] The 5 wt% iron acts as a catalyst for the reverse Boudouard reaction, promoting carbon monoxide generation. When the battery has been running for a sufficiently long period of thousands of hours, catalyst deactivation requires disassembly of the variable-volume anode fuel chamber to replace the catalyst.

[0043] This invention utilizes the electrochemical oxidation of carbon monoxide on the anode side and the concentration difference of water vapor between the anode and cathode of the battery to provide part of the electrical energy required for water electrolysis. It achieves the production of green hydrogen by consuming low-cost hydrocarbon fuels. It uses a fuel-rich flame as the anode fuel gas, so the anode gas does not require external heat source preheating. Moreover, the anode tail gas forms a mixture of carbon monoxide, carbon dioxide and water vapor, which is easy to separate for downstream fuel production. It effectively improves the battery operating efficiency and reduces the cost of hydrogen production by water electrolysis.

[0044] It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.

Claims

1. A low-cost direct carbon solid oxide flame battery for hydrogen production via water electrolysis, characterized in that: The direct carbon solid oxide flame battery is an anode-supported type, comprising a cathode side, an electrolyte layer, and an anode side; the electrolyte layer material is yttrium-stabilized zirconium oxide. The anode side includes an anode layer, a variable-volume anode fuel chamber, and a spring. The spring is connected to the bottom of the variable-volume anode fuel chamber. The anode layer is made of nickel-yttrium-stabilized zirconium oxide. The variable-volume anode fuel chamber includes an anode fuel inlet and an anode exhaust gas outlet; the cathode side includes a cathode layer, a cathode gas diffusion layer and a cathode gas flow channel, the bottom of the cathode gas flow channel is connected to the upper part of the cathode gas diffusion layer, the bottom of the cathode gas diffusion layer is connected to the cathode layer, and the cathode layer material is lanthanum strontium manganese ore-yttrium oxide stabilized zirconium oxide; The cathode side is used as a solid oxide electrolytic cell, where water electrolysis occurs by continuously introducing water vapor into the cathode gas channel; the generated hydrogen gas and unreacted water vapor are discharged on the cathode side, and oxygen ions pass through the electrolyte layer to reach the anode side. The anode side is used as a direct carbon solid oxide flame battery. In the variable volume anode fuel chamber, carbon dioxide gas and activated carbon solid react chemically to generate carbon monoxide. Carbon monoxide and oxygen ions react electrochemically to generate carbon dioxide, which provides some electrical energy for the cathode electrolysis of water. In order to maintain the pressure balance between the anode and cathode of the battery, part of the mixed gas of carbon monoxide, carbon dioxide and water vapor generated at the anode is discharged from the anode tail gas outlet.

2. The low-cost direct carbon solid oxide flame battery for hydrogen production by water electrolysis according to claim 1, characterized in that: The battery has two states: normal operation and shutdown with feeding. In the shutdown and feeding state, first stop the supply of water vapor to the cathode side; open the anode fuel inlet, and the fuel-rich flame generated by the combustion of hydrocarbon fuel mixes with activated carbon near the anode fuel inlet and enters the variable-volume anode fuel chamber until the spring is compressed to its shortest length, then stop feeding and close the anode fuel inlet. In the normal operation state, by continuously supplying water vapor at a temperature of not less than 600°C to the cathode gas flow channel, the battery cathode undergoes the water electrolysis reaction. ； On the anode side, activated carbon containing 5 wt% iron is mixed with a fuel-rich flame in a variable-volume anode fuel chamber, where carbon monoxide electrochemical oxidation and the reverse Boudouard reaction occur. The anode reaction formula is as follows: ； As can be seen from the above reaction formula, under normal operating conditions, every 1 mol of activated carbon fuel consumed generates 2 mol of carbon dioxide. In order to maintain the pressure balance between the anode and cathode of the battery, some gas from the anode is discharged from the anode tail gas outlet during operation.

3. The low-cost direct carbon solid oxide flame battery for hydrogen production by water electrolysis according to claim 2, characterized in that: The fuel-rich flame refers to the flame produced when the oxidant provided is less than the stoichiometric value, and the fuel-rich equivalence ratio is... Defined by the following formula: ； In the formula, and These are the fuel and air flow rates, respectively. The subscript "act" represents the actual flow rate, and "static" represents the flow rate calculated based on the stoichiometric ratio.

4. The low-cost direct carbon solid oxide flame battery for hydrogen production by water electrolysis according to claim 2, characterized in that: The activated carbon fuel and the fuel-rich flame are mixed before entering the variable-volume anode fuel chamber.

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