A high-efficiency electrolyzer

Abstract

This invention discloses a high-efficiency electrolyzer, which comprises a gas supply unit, a solid oxide electrolytic cell stack unit, a thermal management unit, a tail gas separation and recovery unit, and a measurement and control unit. The gas supply unit can supply hydrogen, nitrogen, air, oxygen, and water vapor. The solid oxide electrolytic cell stack unit includes a solid oxide electrolytic cell sub-staple, end plates, and conductive plates. The thermal management unit heats the solid oxide electrolytic cell stack and facilitates heat exchange between the incoming and outgoing gases, ensuring that the internal temperature difference of the stack is controlled within a safe range. The tail gas separation and recovery unit dries the water vapor / hydrogen mixture and separates high-purity hydrogen. The efficiency of this electrolyzer can reach over 90%.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of green hydrogen production, and particularly relates to a high-efficiency electrolytic cell. BACKGROUND

[0002] Hydrogen energy is a clean, pollution-free and long-term storage energy carrier, which will occupy an important position in the future energy structure. Developing electrolytic water hydrogen production technology based on renewable energy power can realize complete decarbonization and has important social significance.

[0003] Currently, the electrolytic water hydrogen production technology includes alkaline electrolytic water technology, proton exchange membrane electrolytic water technology and solid oxide electrolytic cell electrolytic water technology. The solid oxide electrolytic cell has a full solid-state structure, which can avoid the problems of evaporation, corrosion and electrolyte loss caused by the use of liquid electrolyte. The solid oxide electrolytic cell does not need to use noble metal electrodes, and the preparation cost is lower. The solid oxide electrolytic cell operates at high temperature (above 700 DEG C), can be coupled with industrial waste heat, and the electric efficiency can reach 100%, so it is considered as the most efficient electrolytic water hydrogen production technology. The solid oxide electrolytic cell hydrogen production technology needs to solve the key materials, the performance and reliability of the components, and the integration and reliable control of the overall system. Due to the difference in thermal expansion behavior of each component of the solid oxide electrolytic cell operating at high temperature, how to well manage the heat of the system to avoid a large temperature difference in the internal of the electrolytic cell stack is the key to realize the stable and reliable operation of the system. Researchers use the sleeve type heat exchange method to separately heat treat the cathode gas entering and leaving the electrolytic cell stack and the anode gas entering and leaving the electrolytic cell stack, but there are problems of poor heat exchange effect and uneven gas temperature distribution. SUMMARY

[0004] In order to overcome the difficulties in the heat management technology of the solid oxide electrolytic cell electrolytic cell, the large temperature difference in the electrolytic cell stack, and the mismatch of thermal expansion between different components at high temperature leading to system failure, the application provides a high-efficiency electrolytic cell, which is characterized in that the electrolytic cell comprises a gas supply unit, a solid oxide electrolytic cell stack unit, a tail gas separation and recovery unit and a measurement and control unit, and further comprises a heat management unit.

[0005] The heat management unit comprises a heat exchange gas cavity for preheating the cathode gas and the anode gas entering and leaving the electrolytic cell stack, thermocouples for measuring the temperature of multiple points of the electrolytic cell stack, and a heating furnace for heating the solid oxide electrolytic cell stack unit and the heat exchange gas cavity;

[0006] The heat exchange gas cavity is located below the cathode current collector plate of the solid oxide electrolytic cell stack, and the heat exchange gas cavity and the cathode current collector plate are connected through an insulating plate.

[0007] The heat exchange gas cavity is a cavity with pipes inside; the heat exchange gas cavity is connected with the insulation board on one side and has at least four air holes; the air holes are connected with the cathode gas inlet, the anode gas inlet, the cathode gas outlet and the anode gas outlet through the pipes respectively; the cathode gas and the anode gas are respectively introduced into the cathode and the anode of the membrane electrode of the electrolytic cell stack through the air holes;

[0008] The measurement and control unit comprises a power supply providing a voltage higher than the open circuit potential of the electrolytic cell stack, an electromagnetic valve, a gas concentration sensor, a temperature sensor, a humidity sensor, a combustible gas sensor, a current sensor, a voltage sensor, a pressure sensor and a data acquisition module, and the positive and negative poles of the power supply are connected with the anode current collector plate and the cathode current collector plate of the electrolytic cell stack through wires respectively.

[0009] Further, in the above technical solution, the gas supply unit for supplying hydrogen, nitrogen, air, oxygen and water vapor to the electrolytic cell stack unit comprises a gas flow meter, a water pump and a water vapor generator.

[0010] Further, in the above technical solution, the electrolytic cell stack unit is formed by one or more solid oxide electrolytic cell stacks in series or parallel, and the electrolytic cell stack is formed by repeatedly stacking and assembling a cathode current collector plate, an anode current collector plate and a plurality of single cell repeating units through a sealing element.

[0011] Further, in the above technical solution, the tail gas separation and recovery unit for cooling and drying the high-temperature water vapor / hydrogen mixed gas discharged from the electrolytic cell stack to separate high-purity hydrogen comprises a cooler, a dryer and a gas storage device.

[0012] Further, in the above technical solution, the single cell repeating unit of the solid oxide electrolytic cell stack comprises a membrane electrode, a current collecting material, a bipolar plate, a sealing element and a voltage detection line, wherein the sealing element does not change phase from room temperature to the operating temperature range of the electrolytic cell stack, avoiding mutual gas exchange between the gases on both sides of the membrane electrode and the ambient atmosphere.

[0013] Further, in the above technical solution, the sealing element is made of glass powder or a mixture of glass powder and oxide, and the oxide is one or more of ZrO2, Y2O3, TiO2 and Al2O3.

[0014] Further, in the above technical solution, the heat exchange gas cavity is made of heat-resistant alloy material.

[0015] Further, in the above technical solution, the heat exchange gas cavity is made of 310s stainless steel.

[0016] Further, in the above technical solution, in the tail gas separation and recovery unit, the gas in the gas storage device can be circulated and used by being introduced into the gas supply module through a one-way valve.

[0017] Further, in the above technical solution, the measurement and control unit is used for monitoring and adjusting the flow rates of hydrogen, nitrogen, air, oxygen and water vapor; for monitoring and controlling the temperatures of multiple points of the electrolytic cell stack; and for controlling the automatic start and stop of the electrolytic cell stack under different working conditions.

[0018] During the operation of the thermal management unit, the heating furnace heats the solid oxide electrolytic cell stack to maintain the operating temperature required by the system; the heat exchange cavity simultaneously preheats the cathode gas and the anode gas entering and exiting the electrolytic cell stack; the thermocouple measures the temperature at multiple points of the electrolytic cell stack; the heat exchange cavity is located below the cathode current collector plate of the electrolytic cell stack and is connected to the current collector plate through an insulating plate to avoid short circuit between the heat exchange cavity and the current collector plate; during the operation of the electrolytic cell, the cathode gas enters the heat exchange cavity through the cathode gas inlet of the heat exchange cavity, is discharged through one or more gas holes of the heat exchange cavity, and then enters the electrolytic cell stack, the cathode gas reacts in the electrolytic cell stack, then enters the heat exchange cavity again through one or more gas holes of the heat exchange cavity, and finally is discharged through the cathode gas outlet of the heat exchange cavity; the anode gas enters the heat exchange cavity through the anode gas inlet of the heat exchange cavity, is discharged through one or more gas holes of the heat exchange cavity, and then enters the electrolytic cell stack, the anode gas reacts in the electrolytic cell stack, then enters the heat exchange cavity again through one or more gas holes of the heat exchange cavity, and finally is discharged through the anode gas outlet of the heat exchange cavity.

[0019] The present application has the following advantages and benefits:

[0020] 1. The thermal management of the system is reliable, the heat exchange cavity is added below the electrolytic cell stack, the cathode gas and the anode gas entering and exiting the electrolytic cell stack are preheated simultaneously during the operation of the electrolytic cell, the cathode gas enters the heat exchange cavity through the cathode gas inlet of the heat exchange cavity, is discharged through one or more gas holes of the heat exchange cavity, and then enters the electrolytic cell stack, the cathode gas reacts in the electrolytic cell stack, then enters the heat exchange cavity again through one or more gas holes of the heat exchange cavity, and finally is discharged through the cathode gas outlet of the heat exchange cavity; the anode gas enters the heat exchange cavity through the anode gas inlet of the heat exchange cavity, is discharged through one or more gas holes of the heat exchange cavity, and then enters the electrolytic cell stack, the anode gas reacts in the electrolytic cell stack, then enters the heat exchange cavity again through one or more gas holes of the heat exchange cavity, and finally is discharged through the anode gas outlet of the heat exchange cavity. The present application makes the temperature distribution of the gas entering the electrodes on both sides of each single cell uniform, the temperature difference is small, and the temperature distribution of the electrolytic cell is more uniform, and the operation is more reliable.

[0021] 2. The system is modular, especially suitable for 1-10 kW systems, and can be expanded to larger power systems, providing higher flexibility and diversity BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 This is a schematic diagram of the electrolytic cell structure of the present invention;

[0023] Figure 2 This is a schematic diagram of the heat exchange chamber structure.

[0024] In the diagram, 1 is the cathode gas inlet, 2 is pore A, 3 is pore B, 4 is pore C, 5 is pore D, 6 is the cathode gas outlet, 7 is the anode gas inlet, 8 is pore E, 9 is pore F, and 10 is the anode gas outlet. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0026] The seals used in the following electrolytic cells are commercially available products.

[0027] Example 1

[0028] like Figure 1 As shown, a single unit with a hydrogen production capacity of 1m 3 Taking an electrolytic cell with a capacity of / h as an example, it includes a gas supply unit, an electrolytic cell stack unit, a thermal management unit, a tail gas separation and recovery unit, and a measurement and control unit. The heat exchange chamber in the thermal management unit is shown in the attached figure. Figure 2 As shown, the measurement and control unit monitors, measures, and controls the gas supply unit, the electrolytic cell stack unit, the thermal management unit, and the tail gas separation and recovery unit.

[0029] The gas supply unit includes a hydrogen flow meter, a nitrogen flow meter, a horizontal flow pump for water supply, a steam generator, and an air compressor for air supply. The water flow pump supplies high-purity water to the steam generator, which then vaporizes it into steam. The steam temperature is maintained between 110 and 120°C through the pipeline.

[0030] The electrolytic cell stack unit consists of two 2.5kW electrolytic cell stacks connected in series. Each stack comprises 30 single-cell repeating units. The cathode of the membrane electrode in the first single-cell repeating unit is directly connected to the cathode current collector, while the anode of the last single-cell repeating unit is connected to the anode current collector. The cathode of the membrane electrode in one single-cell repeating unit is connected to the anode of the membrane electrode in the adjacent single-cell repeating unit via bipolar plates. Seals are used to connect the membrane electrode and the bipolar plates within a single-cell repeating unit to prevent gas cross-contamination between the membrane electrode and the membrane electrode. Seals are also used to connect the bipolar plates between different single-cell repeating units to prevent gas cross-contamination and short circuits between single-cell repeating units. The stack operates at 600–850℃ with an electrical efficiency of up to 95%.

[0031] like Figure 2As shown, the electrolytic cell stack and the heat exchange gas cavity are placed in a set of electric heating furnace, the thermocouples are placed at the center of the upper, lower, left and right surfaces of the electrolytic cell stack to measure the temperature, the bottom of the cathode current collector plate in each set of electrolytic cell stack is connected with a set of heat exchange gas cavity through mica plate. Different pipes are arranged in the heat exchanger cavity to connect the gas inlet, gas outlet and air holes. When the electrolytic cell is running, the cathode gas water vapor / hydrogen mixture enters the two pipes in the heat exchange gas cavity through the cathode gas inlet 1 of the heat exchange gas cavity, and then is discharged from the air holes A2 and B3 of the heat exchange gas cavity, and then enters the cathode inside of the membrane electrode in the electrolytic cell stack. The water vapor reacts in the electrolytic cell stack to form hydrogen. The water vapor / hydrogen mixture enters the other two pipes in the heat exchange gas cavity through the air holes C4 and D5 of the heat exchange gas cavity, and then is discharged from the cathode gas outlet 6 of the heat exchange gas cavity. At the same time, the anode gas air enters the corresponding pipes in the heat exchange gas cavity through the anode gas inlet 7 of the heat exchange gas cavity, and then is discharged from the air hole E8 of the heat exchange gas cavity, and then enters the oxygen pole inside of the membrane electrode in the electrolytic cell stack. The air exhaust gas discharged from the electrolytic cell stack enters the corresponding pipes in the heat exchange gas cavity through the air hole F9, and then is discharged from the anode gas outlet 10 of the heat exchange gas cavity. The temperature difference between the upper, lower, left and right surfaces of the electrolytic cell stack is ≤30℃.

[0032] The tail gas separation and recovery unit includes a cooler, a dryer and a gas storage device. The high-temperature water vapor and hydrogen mixture discharged from the electrolytic cell stack are cooled and dried to separate high-purity hydrogen. The gas in the gas storage device can be circulated and used in the gas supply module through a one-way valve.

[0033] The measurement and control unit includes a direct current power supply, four electromagnetic valves, four gas concentration sensors, twelve temperature sensors, two humidity sensors, one combustible gas sensor, one set of current sensor, one set of voltage sensor, four pressure sensors and one set of data acquisition module. The positive and negative electrodes of the power supply are connected with the anode current collector plate and the cathode current collector plate of the electrolytic cell stack through wires, respectively, which can provide a voltage higher than the open circuit potential of the electrolytic cell stack. The flow rates of hydrogen, nitrogen, air, oxygen and water vapor can be monitored and adjusted in real time. The temperatures of the fuel gas inlet and outlet of the preheating module, the air outlet and inlet of the heat exchange cavity, and the upper, lower, left and right points of the electrolytic cell stack can be monitored. When the temperature of each point exceeds the specified range, the temperature of the monitoring point can be adjusted to the specified range by adjusting the flow rates of the fuel gas and air. The system can be automatically started.

[0034] Example 2

[0035] A high-efficiency electrolytic cell includes a gas supply unit, a solid oxide electrolytic cell stack unit, a tail gas separation and recovery unit, and a measurement and control unit. It also includes a thermal management unit.

[0036] The heat management unit comprises a heat exchange cavity for preheating cathode gas and anode gas entering and exiting the electrolysis cell stack, a thermocouple for measuring the temperature of multiple points of the electrolysis cell stack, and a heating furnace for heating the solid oxide electrolysis cell stack unit and the heat exchange cavity;

[0037] The heat exchange cavity is located below the cathode current collector plate of the solid oxide electrolysis cell stack, and the heat exchange cavity is connected with the cathode current collector plate through an insulating plate.

[0038] The heat exchange cavity is a cavity with a pipeline inside; at least four gas holes are provided on the side of the heat exchange cavity connected with the insulating plate; the gas holes are respectively connected with the cathode gas inlet, the anode gas inlet, the cathode gas outlet and the anode gas outlet through the pipeline; the cathode gas and the anode gas are respectively introduced into the cathode and the anode of the membrane electrode of the electrolysis cell stack through the gas holes.

[0039] The measurement and control unit comprises a power supply providing an open circuit potential voltage higher than that of the electrolysis cell stack, an electromagnetic valve, a gas concentration sensor, a temperature sensor, a humidity sensor, a combustible gas sensor, a current sensor, a voltage sensor, a pressure sensor and a data acquisition module; the positive and negative poles of the power supply are respectively connected with the anode current collector plate and the cathode current collector plate of the electrolysis cell stack through wires.

[0040] A gas supply unit for supplying hydrogen, nitrogen, air, oxygen and water vapor to the electrolysis cell stack unit, comprising a gas flow meter, a water pump and a water vapor generator.

[0041] The electrolysis cell stack unit is formed by one or more solid oxide electrolysis cell stacks in series or parallel connection; the electrolysis cell stack is formed by repeatedly stacking and assembling a cathode current collector plate, an anode current collector plate and a plurality of single cell repeating units through a sealing element.

[0042] An exhaust gas separation and recovery unit for cooling and drying high-temperature water vapor / hydrogen mixed gas discharged from the electrolysis cell stack, and separating high-purity hydrogen, comprising a cooler, a dryer and a gas storage device.

[0043] The single cell repeating unit of the solid oxide electrolysis cell stack comprises a membrane electrode, a current collecting material, a bipolar plate, a sealing element and a voltage detection line; the sealing element does not change phase from room temperature to the operating temperature of the electrolysis cell stack, avoiding mutual gas exchange between the gases on both sides of the membrane electrode and the ambient atmosphere.

[0044] The sealing element is made of glass powder or a mixture of glass powder and oxide, wherein the oxide is one or more of ZrO2, Y2O3, TiO2 and Al2O3.

[0045] Further, in the above technical solution, the heat exchange cavity is made of heat-resistant alloy material.

[0046] The heat exchange gas cavity is made of 310s stainless steel.

[0047] In the tail gas separation and recovery unit, the gas in the gas storage device can pass through the one-way valve into the gas supply module for circulation.

[0048] The measurement and control unit is used for monitoring and adjusting the flow of hydrogen, nitrogen, air, oxygen and water vapor, monitoring and controlling the temperature of multiple points of the electrolysis cell stack, and controlling the automatic start and stop of the electrolysis cell stack under different working conditions.

Claims

1. A high efficiency electrolytic cell characterized by: The electrolytic cell comprises a gas supply unit, a solid oxide electrolytic cell stack unit, a tail gas separation and recovery unit, and a measurement and control unit. The electrolytic cell further comprises a heat management unit, which comprises a heat exchange cavity for preheating cathode gas and anode gas entering and exiting the electrolytic cell stack, thermocouples for measuring the temperature of multiple points of the electrolytic cell stack, and a heating furnace for heating the solid oxide electrolytic cell stack unit and the heat exchange cavity. The heat exchange cavity is located below the cathode current collector plate of the solid oxide electrolytic cell stack, and the heat exchange cavity and the cathode current collector plate are connected through an insulating plate. The heat exchange cavity is a cavity with a pipeline inside. At least four gas holes are provided on the side of the heat exchange cavity connected with the insulating plate. The gas holes are respectively connected with the cathode gas inlet, the anode gas inlet, the cathode gas outlet, and the anode gas outlet through the pipeline. The measurement and control unit comprises a power supply providing an open-circuit potential voltage higher than the electrolytic cell stack, solenoid valves, gas concentration sensors, temperature sensors, humidity sensors, combustible gas sensors, current sensors, voltage sensors, pressure sensors, and a data acquisition module. The positive and negative poles of the power supply are respectively connected with the anode current collector plate and the cathode current collector plate of the electrolytic cell stack through wires. The cathode gas enters the heat exchange cavity through the cathode gas inlet of the heat exchange cavity, is discharged through one or more gas holes of the heat exchange cavity, and then enters the electrolytic cell stack. After the cathode gas reacts in the electrolytic cell stack, it enters the heat exchange cavity again through one or more gas holes of the heat exchange cavity, and is finally discharged through the cathode gas outlet of the heat exchange cavity. The anode gas enters the heat exchange cavity through the anode gas inlet of the heat exchange cavity, is discharged through one or more gas holes of the heat exchange cavity, and then enters the electrolytic cell stack. After the anode gas reacts in the electrolytic cell stack, it enters the heat exchange cavity again through one or more gas holes of the heat exchange cavity, and is finally discharged through the anode gas outlet of the heat exchange cavity.

2. The high efficiency electrolytic cell of claim 1, wherein: The gas supply unit is used to supply hydrogen, nitrogen, air, oxygen, and water vapor to the electrolytic cell stack unit, and comprises a gas flow meter, a water pump, and a water vapor generator.

3. The high efficiency electrolytic cell of claim 1, wherein: The electrolytic cell stack unit is formed by one or more solid oxide electrolytic cell stacks connected in series or parallel. The electrolytic cell stack is formed by repeatedly stacking and assembling a cathode current collector plate, an anode current collector plate, and a plurality of single-cell repeating units connected by a sealing element.

4. The high efficiency electrolytic cell of claim 1, wherein: The tail gas separation and recovery unit is used to cool and dry the high-temperature water vapor / hydrogen mixed gas discharged from the electrolytic cell stack, and separate high-purity hydrogen. The unit comprises a cooler, a dryer, and a gas storage device.

5. The high efficiency electrolytic cell of claim 1, wherein: The single-cell repeating unit of the solid oxide electrolytic cell stack comprises a membrane electrode, a current collecting material, a bipolar plate, a sealing element, and a voltage detection line. The sealing element prevents gas from flowing between the two sides of the membrane electrode and the environment.

6. The high efficiency electrolytic cell of claim 5, wherein: The sealing element is made of glass powder or a mixture of glass powder and oxide. The oxide is one or more of ZrO2, Y2O3, TiO2, and Al2O3.

7. The high efficiency electrolytic cell of claim 1, wherein: The heat exchange cavity is made of heat-resistant alloy.

8. The high efficiency electrolytic cell of claim 7, wherein: The heat exchange cavity is made of 310s stainless steel.

9. The high efficiency electrolytic cell of claim 1, wherein: In the tail gas separation and recovery unit, the gas in the gas storage device can be circulated and used in the gas supply unit through a one-way valve.

10. The high efficiency electrolytic cell of claim 1, wherein: The measurement and control unit is used for monitoring and adjusting the flow of hydrogen, nitrogen, air, oxygen and water vapor; for monitoring and controlling the temperature of multiple points of the electrolytic cell stack; for controlling the automatic start and stop of the electrolytic cell stack under different working conditions.

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