Solid oxide hydrogen production system and method

Abstract

The invention relates to the technical field of solid oxide hydrogen production, and discloses a system and method for solid oxide hydrogen production, and the system comprises an SOEC electric pile which comprises a hydrogen electrode side inlet, a hydrogen electrode side outlet, an oxygen electrode side inlet and an oxygen electrode side outlet; the first raw material gas supply unit comprises a hydrogen shielding gas supply device, a water vapor supply device, a mixer, a hydrogen electrode side heat exchanger and a hydrogen electrode side preheater; an inlet of the mixer is communicated with a hydrogen shielding gas supply device and a water vapor supply device; the second raw material gas supply unit comprises an air supply device, an air heat exchanger and an oxygen electrode side preheater which are communicated in sequence; according to the system, the electrolysis efficiency can be improved, sufficient energy gradient utilization is carried out on tail gas waste heat of the SOEC electric pile, the total energy consumption of the system is reduced, and the hydrogen production efficiency is high.

Description

Technical Field

[0001] This invention relates to the field of solid oxide hydrogen production technology, and more specifically to a system and method for solid oxide hydrogen production. Background Technology

[0002] Solid oxide electrolysis (SOEC) is a highly efficient energy conversion device that converts electrical and thermal energy into the chemical energy of fuels such as hydrogen, methanol, and natural gas. It has advantages such as high efficiency, low emissions, low pollution, and wide application, making it one of the most popular energy conversion technologies. It has enormous research and development potential and has attracted widespread international attention.

[0003] Compared with other hydrogen production technologies, SOEC has the outstanding advantages of low electrolysis energy consumption and high electrolysis efficiency. However, since this technology operates in a high-temperature environment of 600-00℃, the system operation involves multiple stages of heat utilization. Strengthening thermal management and efficient utilization of heat is particularly important for improving system efficiency.

[0004] CN113930799A discloses a heat recovery system for hydrogen production in a solid oxide electrolyzer, comprising a water storage tank, a solar panel, a low-temperature metal hydrogen storage tank, an evaporator, a high-temperature metal hydrogen storage tank, a heat exchanger, a solid oxide electrolyzer, a separator, and a reactor. Water from the water storage tank undergoes multi-stage heat exchange through the solar panel, the low-temperature metal hydrogen storage tank, the evaporator, the high-temperature metal hydrogen storage tank, and the heat exchanger. The resulting water vapor, reaching the operating temperature, enters the solid oxide electrolyzer. The hydrogen generated after the electrochemical reaction and the unused water vapor flow out from the cathode product outlet of the solid oxide electrolyzer. The hydrogen vapor first exchanges heat with the water vapor to be reacted through the heat exchanger, but the electrolysis efficiency is still insufficient, and heat utilization is inadequate. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of low electrolysis efficiency, low thermal utilization rate, and high energy consumption in existing SOEC systems, and to provide a system and method for producing hydrogen from solid oxides, which has high electrolysis efficiency and thermal utilization rate.

[0006] To achieve the above objectives, the present invention provides a system for producing hydrogen from a solid oxide, the system comprising:

[0007] SOEC stack 8 includes a hydrogen electrode side inlet, a hydrogen electrode side outlet, an oxygen electrode side inlet, and an oxygen electrode side outlet;

[0008] The first feed gas supply unit includes a hydrogen protective gas supply device, a steam supply device, a mixer 3, a hydrogen electrode side heat exchanger 4, and a hydrogen electrode side preheater 5. The inlet of the mixer 3 is connected to the hydrogen protective gas supply device and the steam supply device, and is used to mix the hydrogen from the hydrogen protective gas supply device and the steam from the steam supply device to obtain the first feed gas. The inlet of the hydrogen electrode side heat exchanger 4 is connected to the outlet of the mixer 3, and the heat medium inlet of the hydrogen electrode side heat exchanger 4 is connected to the hydrogen electrode side outlet of the SOEC stack 8, and is used to perform a first heat exchange between the tail gas from the hydrogen electrode side outlet and the first feed gas. The first feed gas outlet of the hydrogen electrode side heat exchanger 4 is connected to the inlet of the hydrogen electrode side preheater 5, and the outlet of the hydrogen electrode side preheater 5 is connected to the hydrogen electrode side inlet of the SOEC stack.

[0009] The second raw material gas supply unit includes an air supply device, an air heat exchanger 6, and an oxygen electrode side preheater 7 connected in sequence. The heat medium inlet of the air heat exchanger 6 is connected to the oxygen electrode side outlet of the SOEC stack 8, and is used to perform a second heat exchange between the exhaust gas from the oxygen electrode side outlet and the air from the air supply device. The air outlet of the air heat exchanger 6 is connected to the inlet of the oxygen electrode side preheater 7, and the outlet of the oxygen electrode side preheater 7 is connected to the oxygen electrode inlet of the SOEC stack.

[0010] Another aspect of the present invention provides a method for producing hydrogen from a solid oxide, the method being carried out in the system described in the first aspect, the method comprising the following steps:

[0011] (1) Hydrogen gas and water vapor are mixed in a mixer to obtain the first raw material gas;

[0012] Based on the volumetric flow rate of the water vapor, the volumetric amount of hydrogen is 4-20%.

[0013] (2) The first raw material gas and the tail gas from the hydrogen electrode side outlet are subjected to the first heat exchange in the hydrogen electrode side heat exchanger, and then the gas is preheated by the hydrogen electrode side preheater and sent to the hydrogen electrode side of the SOEC stack.

[0014] (3) The air and the tail gas from the oxygen electrode side outlet are subjected to a second heat exchange in the air heat exchanger, and then the air is preheated by the oxygen electrode side preheater before being sent to the oxygen electrode side of the SOEC stack.

[0015] The solid oxide hydrogen production system provided by this invention adds a hydrogen protective gas to the hydrogen electrode side, which can effectively reduce the oxidation of the hydrogen electrode by high-temperature water vapor and improve the electrolysis efficiency. At the same time, through multi-stage heat exchangers and preheaters, the waste heat of SOEC stack tail gas is fully utilized in a cascade manner, reducing the total energy consumption of the system and improving the overall hydrogen production efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a solid oxide hydrogen production system according to the present invention.

[0017] Explanation of reference numerals in the attached figures

[0018] 1- Hydrogen protective gas heat exchanger; 2- Steam generator; 3- Mixer; 4- Hydrogen electrode side heat exchanger; 5- Hydrogen electrode side preheater; 6- Air heat exchanger; 7- Oxygen electrode side preheater; 8- SOEC stack; 9- Stack heat box; 10- Waste heat recovery heat exchanger; 11- Hydrogen production power regulator. Detailed Implementation

[0019] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0020] In this invention, the terms "first," "second," "third," and "fourth" in "first heat exchange," "second heat exchange," "third heat exchange," and "fourth heat exchange" are used only to distinguish different heat exchange processes and do not define their heat exchange sequence.

[0021] A first aspect of the present invention provides a system for producing hydrogen from solid oxides, the system comprising:

[0022] SOEC stack 8 includes a hydrogen electrode side inlet, a hydrogen electrode side outlet, an oxygen electrode side inlet, and an oxygen electrode side outlet;

[0023] The first feed gas supply unit includes a hydrogen protective gas supply device, a steam supply device, a mixer 3, a hydrogen electrode side heat exchanger 4, and a hydrogen electrode side preheater 5. The inlet of the mixer 3 is connected to the hydrogen protective gas supply device and the steam supply device, and is used to mix the hydrogen from the hydrogen protective gas supply device and the steam from the steam supply device to obtain the first feed gas. The inlet of the hydrogen electrode side heat exchanger 4 is connected to the outlet of the mixer 3, and the heat medium inlet of the hydrogen electrode side heat exchanger 4 is connected to the hydrogen electrode side outlet of the SOEC stack 8, and is used to perform a first heat exchange between the tail gas from the hydrogen electrode side outlet and the first feed gas. The first feed gas outlet of the hydrogen electrode side heat exchanger 4 is connected to the inlet of the hydrogen electrode side preheater 5, and the outlet of the hydrogen electrode side preheater 5 is connected to the hydrogen electrode side inlet of the SOEC stack.

[0024] The second raw material gas supply unit includes an air supply device, an air heat exchanger 6, and an oxygen electrode side preheater 7 connected in sequence. The heat medium inlet of the air heat exchanger 6 is connected to the oxygen electrode side outlet of the SOEC stack 8, and is used to perform a second heat exchange between the exhaust gas from the oxygen electrode side outlet and the air from the air supply device. The air outlet of the air heat exchanger 6 is connected to the inlet of the oxygen electrode side preheater 7, and the outlet of the oxygen electrode side preheater 7 is connected to the oxygen electrode inlet of the SOEC stack.

[0025] The present invention does not particularly limit the structure and composition of the SOEC stack, which can be a conventional solid oxide electrolytic cell in the art. Preferably, the operating temperature of the SOEC stack is 600-800℃.

[0026] To further reduce the overall energy consumption of SOEC systems and improve their overall hydrogen production efficiency, this invention provides a solid oxide hydrogen production system from a thermal management perspective. Through multi-stage heat exchangers and preheaters, the system fully utilizes the waste heat from the oxygen electrode and hydrogen electrode tail gases of the SOEC stack, reducing overall system energy consumption and dependence on external heat sources. Particularly when the hydrogen electrode of the SOEC stack is a Ni-YSZ (yttrium oxide-stabilized zirconium oxide-supported nickel electrode), hydrogen is introduced to the hydrogen electrode side via a hydrogen protective gas supply device. This effectively reduces the oxidation of nickel in the hydrogen electrode by high-temperature water vapor, ensuring electrolysis efficiency. This overall solution improves the overall hydrogen production efficiency.

[0027] According to some preferred embodiments of the present invention, the steam supply device includes a water supply device and a steam generator 2; the hydrogen protective gas supply device includes a hydrogen supply device and a hydrogen protective gas heat exchanger 1. The water supply device can be a water storage tank, water supply pipeline, etc., used to provide liquid water, and the steam generator is used to evaporate the liquid water to generate steam. The present invention does not have any particular requirements on the specific type of steam generator, as long as it can achieve the above objectives.

[0028] In the preferred embodiment described above, the system further includes a waste heat recovery heat exchanger 10; the inlet of the waste heat recovery heat exchanger 10 is connected to the medium outlet of the hydrogen electrode side heat exchanger 4 and the medium outlet of the air heat exchanger 6 respectively, and the waste heat from the medium of the hydrogen electrode side heat exchanger 4 and the air heat exchanger 6 is used to perform a third heat exchange with cold water, and the hot water obtained from the third heat exchange is used to provide a water source for the steam supply device.

[0029] In a further preferred embodiment, the outlet of the waste heat recovery heat exchanger 10 is connected to the hydrogen protective gas heat exchanger 1. Hot water obtained from the waste heat recovery heat exchanger 10 undergoes a fourth heat exchange with hydrogen from the hydrogen supply device. The aqueous phase after the fourth heat exchange is then sent to the water supply device to provide water for the steam supply device. Firstly, the hot water obtained from the third heat exchange is sent to the hydrogen protective gas heat exchanger 1 to provide the heat source for the fourth heat exchange. This preheats the hydrogen before it mixes with the steam, which helps increase the steam temperature and improves the efficiency of the subsequent electrolysis. Secondly, it ensures full utilization of the heat from the waste heat recovery heat exchanger, thereby improving the system's thermal efficiency.

[0030] In this invention, there are no particular limitations on the types of the hydrogen protective gas heat exchanger 1, the hydrogen electrode side heat exchanger 4, the air heat exchanger 6, and the waste heat recovery heat exchanger 10. The types of each device can be the same or different, and all can be conventional heat exchange devices in the art, as long as they can achieve heat exchange between media at different temperatures. For example, they can be conventional shell-and-tube heat exchangers, plate heat exchangers, finned heat exchangers, coaxial heat exchangers, etc.

[0031] According to the present invention, preferably, the system further includes a fuel cell stack heating box 9, which is disposed outside the SOEC fuel cell stack and is used to provide a constant temperature heat source for the SOEC fuel cell stack. The start-up heat source of the fuel cell stack heating box can be natural gas combustion heating or other heating methods. The present invention provides a wide range of choices for the structure of the fuel cell stack heating box, as long as it can have a good heat preservation effect.

[0032] To further facilitate self-heating balance during SOEC stack operation and reduce or eliminate the use of external heat sources, the stack heating box 9 preferably includes an aluminum silicate plate and a nano-insulation layer arranged sequentially from the inside to the outside, as well as heating wires attached to or embedded in the inner surface of the aluminum silicate plate.

[0033] By adopting the above-mentioned preferred electric stack heat box, heat dissipation energy consumption can be reduced, the overall efficiency of SOEC system can be improved, and the problems of high cost of insulation layer and high heat dissipation energy consumption of current SOEC system can be overcome.

[0034] In this invention, the heating element is attached to or embedded in the inner surface of the aluminum silicate board through the composite insulation structure of aluminum silicate board and nano-insulation layer. The aluminum silicate board serves as the support for the heating element and the supporting frame structure for the large-area insulation layer, mainly playing the role of heat insulation support. This can reduce the requirements for the insulation effect of the aluminum silicate board, thereby significantly reducing the thickness of the aluminum silicate board.

[0035] According to the present invention, preferably, the thickness of the aluminum silicate plate is such that the outer surface temperature is reduced to below 600°C after the aluminum silicate plate is used for heat insulation.

[0036] In a further preferred embodiment, the thickness of the aluminum silicate plate is 30-50mm, preferably 30-40mm, for example, it can be a specific thickness value such as 30mm, 32mm, 35mm, 36mm, 38mm, 40mm or any range between two of them.

[0037] In a further preferred embodiment, the strength of the aluminum silicate plate is not less than 10 MPa.

[0038] In this invention, the strength refers to compressive strength, which is measured by a tensile testing instrument.

[0039] In this invention, the aluminum silicate plate can be prepared using any conventional method in the art, and this invention does not have any particular limitations.

[0040] In this invention, the inner surface of the aluminum silicate plate refers to the surface closest to the SOEC stack body.

[0041] In this invention, the heating wire can be attached to the inner surface of the aluminum silicate plate, or it can be embedded in the inner surface of the aluminum silicate plate. In this invention, the "embedding" is achieved by partially embedding the heating wire into the aluminum silicate plate, with the remaining portion exposed.

[0042] According to the present invention, the distance between the heating wire and the outer surface of the aluminum silicate plate is not less than 20% of the total thickness of the aluminum silicate plate. Preferably, the distance between the heating wire and the outer surface of the aluminum silicate plate is 20%-60% of the total thickness of the aluminum silicate plate. In the present invention, the distance between the heating wire and the outer surface of the aluminum silicate plate refers to the distance from the outer surface of the aluminum silicate plate to the deepest point where the heating wire is embedded in the aluminum silicate plate.

[0043] According to some preferred embodiments of the present invention, the distance between the heating element and the outer surface of the aluminosilicate plate is 10-20 mm, for example, it can be a specific distance such as 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm, or any distance between two options. Preferably, the distance between the heating element and the outer surface of the aluminosilicate plate is 10-15 mm. Controlling the distance between the heating element and the outer surface of the aluminosilicate plate within the above-mentioned preferred range is beneficial to further improve the overall heat preservation effect.

[0044] In this invention, the outer surface of the aluminum silicate plate refers to the side surface away from the SOEC stack body.

[0045] In this invention, the selection range for the nano-insulation layer is relatively wide, as long as it can achieve a heat insulation effect. Microporous insulation materials, nanoporous insulation board materials, nano-aerogel insulation materials, etc., can be used to form the aforementioned nano-insulation layer. These materials typically have poor mechanical strength and, in existing technologies, can only be used as filler materials to achieve a heat insulation effect. This invention places them on the outside of the aluminum silicate board, forming a composite insulation layer that can achieve a better heat insulation effect and helps to reduce the thickness of the insulation layer.

[0046] According to some preferred embodiments of the present invention, the nano-insulation layer is selected from at least one of a variety of insulation materials such as nano-aerogel insulation layer, nano-microporous material insulation layer, and nano-insulation board.

[0047] Furthermore, when the nano-insulation layer is bonded to the aluminum silicate board, it is necessary to ensure flatness and tightness to prevent the nano-insulation layer from becoming soft and falling off during the insulation process, which would affect the overall insulation effect.

[0048] According to some preferred embodiments of the present invention, the thickness of the nano-insulation layer is such that the outer surface temperature is reduced to below 60°C after the nano-insulation layer has been used for heat insulation.

[0049] According to some preferred embodiments of the present invention, the thickness of the nano-insulation layer is 50-100 mm, for example, it can be a specific thickness value such as 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, or any range between two. Preferably, the thickness of the nano-insulation layer is 50-80 mm. Controlling the thickness of the nano-insulation layer within the above-mentioned preferred range is beneficial to further improve the overall insulation effect.

[0050] According to the present invention, preferably, the system further includes: a hydrogen production power regulator 11, which can adjust the power at any time according to the fluctuation of the hydrogen production power supply, and then feed back to adjust the flow rate and pressure of water vapor and air in the intake, so that the whole system can achieve dynamic thermal balance and material balance, and ensure the safe and reliable operation of the system.

[0051] A second aspect of the present invention provides a method for producing hydrogen from a solid oxide, the method being carried out in the system described in the first aspect, the method comprising the following steps:

[0052] (1) Hydrogen gas and water vapor are mixed in a mixer to obtain the first raw material gas;

[0053] Based on the volumetric flow rate of the water vapor, the volumetric amount of hydrogen is 4-20%.

[0054] (2) The first raw material gas and the tail gas from the hydrogen electrode side outlet are subjected to the first heat exchange in the hydrogen electrode side heat exchanger, and then the gas is preheated by the hydrogen electrode side preheater and sent to the hydrogen electrode side of the SOEC stack.

[0055] (3) The air and the tail gas from the oxygen electrode side outlet are subjected to a second heat exchange in the air heat exchanger, and then the air is preheated by the oxygen electrode side preheater before being sent to the oxygen electrode side of the SOEC stack.

[0056] In this invention, by mixing hydrogen with water vapor and introducing an appropriate amount of hydrogen to the hydrogen electrode side, the oxidation of the hydrogen electrode by high-temperature water vapor can be effectively reduced, ensuring electrolysis efficiency. The overall hydrogen production efficiency is improved through this comprehensive approach. In this invention, based on the volumetric flow rate of the water vapor, the volumetric amount of hydrogen is 4-20%, for example, it can be a specific volumetric amount of 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 16%, 18%, 20%, or any range between two. Preferably, based on the volumetric flow rate of the water vapor, the volumetric amount of hydrogen is 6-8%. Using the above preferred embodiment helps prevent oxidation of the nickel electrode on the hydrogen electrode side, ensuring the electrolysis reaction proceeds. Excessive hydrogen usage may cause a reverse electrolysis reaction (generating electricity with the air on the oxygen electrode side); insufficient hydrogen usage may fail to prevent oxidation of the nickel electrode on the hydrogen electrode side.

[0057] In this invention, water vapor is provided by a steam generator, and the temperature of the water vapor is greater than 100°C.

[0058] According to some preferred embodiments of the present invention, step (1) includes: performing a fourth heat exchange on hydrogen in a hydrogen protective gas heat exchanger 1, so that the temperature of the hydrogen after heat exchange is above 100°C, and then mixing it with water vapor in a mixer. The heat source of the hydrogen protective gas heat exchanger 1 can be at least one of low-quality waste heat from chemical plants, nuclear power plants, etc., or heat from the waste heat recovery unit 10, as long as it can meet the above-mentioned hydrogen temperature requirements after heat exchange. Preferably, the hot water after heat exchange in the waste heat recovery heat exchanger 10 and the hydrogen are subjected to a fourth heat exchange in the hydrogen protective gas heat exchanger 1.

[0059] According to the present invention, SOEC is typically operated in a high-temperature environment of 600-800°C. The composition of the exhaust gas at the hydrogen electrode outlet includes H2 and water vapor. Preferably, the temperature of the exhaust gas at the hydrogen electrode outlet is not lower than 700°C.

[0060] In this invention, the first raw material gas and the tail gas from the outlet of the hydrogen electrode side are subjected to a first heat exchange in a heat exchanger on the hydrogen electrode side. Preferably, the first heat exchange results in the temperature of the first raw material gas after the heat exchange being not lower than 400°C, and more preferably 400-600°C.

[0061] After the first heat exchange raises the temperature of the first feed gas to above 400°C, it is further preheated by the hydrogen electrode side preheater, which can further increase the temperature of the feed gas. The heat source for the hydrogen electrode side preheater can be high-quality waste heat from chemical plants, nuclear power plants, etc. Preferably, the temperature of the first feed gas after preheating by the hydrogen electrode side preheater is not lower than 750°C, and more preferably 750-800°C.

[0062] According to the present invention, the exhaust gas at the oxygen electrode side outlet comprises O2 and N2. Preferably, the temperature of the exhaust gas at the oxygen electrode side outlet is not lower than 700°C.

[0063] In this invention, the air and the exhaust gas from the oxygen electrode outlet undergo a second heat exchange in an air heat exchanger. Preferably, the second heat exchange results in the air temperature after the heat exchange being not lower than 400°C, and more preferably 400-600°C.

[0064] After the air temperature is raised to above 400°C through the second heat exchange, it is further preheated by the oxygen electrode side preheater, which can further increase the air temperature. The heat source for the oxygen electrode side preheater can be high-quality waste heat from chemical plants, nuclear power plants, etc. Preferably, the air temperature after preheating by the oxygen electrode side preheater is not lower than 750°C, and more preferably 750-800°C.

[0065] In this invention, the heat source of the waste heat recovery heat exchanger 10 comes from the heat exchanged between the hydrogen electrode side heat exchanger 4 and the air heat exchanger 6. The heat recovery method mainly involves heat exchange with cold water, and the hot water after heat exchange can be used as the water source for the steam generator 2.

[0066] According to a specific embodiment of the present invention, such as Figure 1As shown, hydrogen protective gas enters hydrogen protective gas heat exchanger 1 for the fourth heat exchange, while feedwater enters steam generator 2 to obtain steam. After the fourth heat exchange, the hydrogen and steam enter mixer 3 for thorough mixing, and then are sent to hydrogen electrode side heat exchanger 4. There, the exhaust gas from the hydrogen electrode side outlet undergoes the first heat exchange to a temperature above 400°C. Then, it is preheated to above 700°C by hydrogen electrode side preheater before being sent to the hydrogen electrode side of the SOEC stack. Air supplied by air pressure undergoes the second heat exchange with the exhaust gas from the oxygen electrode side outlet through air heat exchanger 6, reaching a temperature above 400°C, and then is sent to oxygen electrode side preheater 7, where it is preheated to above 700°C. Then, the gas is fed into the oxygen electrode inlet of SOEC stack 8; the tail gas temperatures of the hydrogen electrode and oxygen electrode are exchanged through the hydrogen electrode side heat exchanger 4 and the air heat exchanger 6, respectively, and then enter the waste heat recovery heat exchanger 10. After heat exchange with cold water, it can be further fully exchanged with the hydrogen protective gas heat exchanger 1, and the temperature is reduced to below 40°C before being sent to the feedwater of the steam generator; the stack heat box 9 provides a constant temperature heat source for the SOEC stack body; the hydrogen production power regulator 11 can adjust the power at any time according to the fluctuation of the hydrogen production power supply, and then feed back to regulate the flow rate and pressure of the steam and air in the intake, so that the entire system can achieve dynamic thermal balance and material balance, and ensure the safe and reliable operation of the system.

[0067] The present invention will be described in detail below through embodiments.

[0068] Example 1

[0069] Adopting such Figure 1 The solid oxide hydrogen production system shown has a Ni-YSZ hydrogen electrode in its SOEC (Solar Electrode Array) fuel cell stack. An external heat exchanger 9 is installed on the SOEC stack. The heat exchanger 9 comprises an aluminosilicate plate and a nano-insulation layer arranged sequentially from the inside out. Heating wires are embedded in the inner surface of the aluminosilicate plate, with a distance of 20 mm between the heating wires and the outer surface of the aluminosilicate plate. The aluminosilicate plate is 30 mm thick and has a strength of 10 MPa. The nano-insulation layer uses DRT10 nano-aerogel insulation material produced by Guangdong Elisheng Technology Co., Ltd., and has a thickness of 70 mm.

[0070] Hydrogen protective gas enters heat exchanger 1, and feedwater enters steam generator 2. The steam flow rate is 100 L / min, and the hydrogen protective gas flow rate is 6 L / min. After heat exchange, the hydrogen temperature reaches 110°C, and the steam output from the steam generator also reaches 110°C. The two gases then enter mixer 3 and are thoroughly mixed before entering hydrogen electrode-side heat exchanger 4. After heat exchange, the temperature reaches 115°C and enters hydrogen electrode-side preheater 5. After high-temperature preheating, the mixed gas temperature reaches 750°C and enters the hydrogen electrode inlet of SOEC stack 8. Air supplied by air pressure enters oxygen electrode-side preheater 7 after heat exchange in air heat exchanger 6, reaching a temperature of 480°C. After preheating to 750°C, the air enters oxygen electrode inlet of SOEC stack 8.

[0071] The exhaust gas temperature of the hydrogen electrode and oxygen electrode is 730℃. After passing through the hydrogen electrode side heat exchanger 4 and the air heat exchanger 6 respectively, the temperature drops to 350℃. It enters the waste heat recovery heat exchanger 10, and after heat exchange with cold water, the temperature drops to 50℃. It then undergoes further heat exchange with the hydrogen protective gas heat exchanger, and the temperature drops to 40℃ before being sent to the feed water of the steam generator. The hydrogen production power regulator 11 can adjust the power at any time according to the fluctuation of the hydrogen production power supply, and then feed back to regulate the flow rate and pressure of the incoming steam and air, so that the entire system can achieve dynamic thermal balance and material balance, ensuring the safe and reliable operation of the system.

[0072] Under this operating condition, the nickel electrode on the hydrogen electrode side is not oxidized, the entire electrolysis reaction process is relatively stable, the overall electrolysis efficiency is high, waste heat recovery and other utilization are good, and the total hydrogen production energy consumption is relatively ideal.

[0073] Example 2

[0074] Adopting such Figure 1 The system shown has a Ni-YSZ hydrogen electrode in the SOEC fuel cell stack. An external heating box 9 is installed on the SOEC fuel cell stack. The heating box 9 comprises an aluminosilicate plate and a nano-insulation layer arranged sequentially from the inside out. Heating wires are attached to the inner surface of the aluminosilicate plate. The aluminosilicate plate is 30 mm thick and has a strength of 10 MPa. The nano-insulation layer uses HT-350 nanoporous insulation material from Sanmenxia Xihongtai Furnace Industry Technology Co., Ltd., and has a thickness of 70 mm.

[0075] Hydrogen protective gas enters hydrogen protective gas heat exchanger 1, and feedwater enters steam generator 2. The steam flow rate is 100 L / min, and the hydrogen protective gas flow rate is 8 L / min. After heat exchange, the hydrogen temperature reaches 110℃, and the steam output temperature from the steam generator is 110℃. After the two enter mixer 3 and are thoroughly mixed, they enter hydrogen electrode side heat exchanger 4. After heat exchange, the temperature reaches 450℃ and enters hydrogen electrode side preheater 5. After high-temperature preheating, the mixed gas temperature reaches 750℃ and enters the hydrogen electrode inlet of the SOEC stack. Air supplied by air pressure enters the oxygen electrode side preheater 7 after heat exchange in air heat exchanger 6, reaching a temperature of 450℃. After preheating to 750℃, the air enters the oxygen electrode inlet of SOEC stack 8.

[0076] The exhaust gas temperature of the hydrogen electrode and oxygen electrode is 730℃. After passing through the hydrogen electrode side heat exchanger 4 and the air heat exchanger 6 respectively, the temperature drops to 350℃. It enters the waste heat recovery heat exchanger 10, and after heat exchange with cold water, the temperature drops to 60℃. It then undergoes further heat exchange with the hydrogen protective gas heat exchanger 1, and the temperature drops to 40℃ before being sent to the feed water of the steam generator. The hydrogen production power regulator 11 can adjust the power at any time according to the fluctuation of the hydrogen production power supply, and then feed back to regulate the flow rate and pressure of the incoming steam and air, so that the entire system can achieve dynamic thermal balance and material balance, ensuring the safe and reliable operation of the system.

[0077] Under this condition, the nickel electrode on the hydrogen electrode side was not oxidized, the entire electrolysis reaction process was relatively stable, and the overall electrolysis efficiency and hydrogen production energy consumption were similar to those in Example 1.

[0078] Example 3

[0079] Adopting such Figure 1 The solid oxide hydrogen production system shown has a Ni-YSZ hydrogen electrode in its SOEC stack. An external heat exchanger 9 is installed on the SOEC stack. The heat exchanger 9 comprises an aluminosilicate plate and a nano-insulation layer arranged sequentially from the inside out. Heating wires are embedded in the inner surface of the aluminosilicate plate, with a distance of 20 mm between the heating wires and the outer surface of the aluminosilicate plate. The aluminosilicate plate is 30 mm thick and has a strength of 10 MPa. The nano-insulation layer uses DRT10 nano-aerogel insulation material produced by Guangdong Elisheng Technology Co., Ltd., and has a thickness of 70 mm.

[0080] Hydrogen protective gas enters hydrogen protective gas heat exchanger 1, and feedwater enters steam generator 2. The steam flow rate is 100 L / min, and the hydrogen protective gas flow rate is 4 L / min. After heat exchange, the hydrogen temperature reaches 110℃, and the steam output temperature from the steam generator is 110℃. After the two enter mixer 3 and are thoroughly mixed, they enter hydrogen electrode side heat exchanger 4. After heat exchange, the temperature reaches 450℃ and enters hydrogen electrode side preheater 5. After high-temperature preheating, the mixed gas temperature reaches 750℃ and enters the hydrogen electrode inlet of SOEC stack 8. Air supplied by air pressure enters oxygen electrode side preheater 7 after heat exchange in air heat exchanger 6, reaching a temperature of 450℃. After preheating to 750℃, the air enters oxygen electrode inlet of SOEC stack 8.

[0081] The exhaust gas temperature of the hydrogen electrode and oxygen electrode is 720℃. After passing through the hydrogen electrode side heat exchanger 4 and the air heat exchanger 6 respectively, the temperature drops to 360℃. It enters the waste heat recovery heat exchanger 10, and after heat exchange with cold water, the temperature drops to 60℃. It then undergoes further heat exchange with the hydrogen protective gas heat exchanger 1, and the temperature drops to 40℃ before being sent to the feed water of the steam generator. The hydrogen production power regulator 11 can adjust the power at any time according to the fluctuation of the hydrogen production power supply, and then feed back to regulate the flow rate and pressure of the incoming steam and air, so that the entire system can achieve dynamic thermal balance and material balance, ensuring the safe and reliable operation of the system.

[0082] A small area of ​​the nickel electrode on the hydrogen electrode side is oxidized, and the total energy consumption for hydrogen production is larger than that in Example 1 under the same hydrogen production power adjustment.

[0083] Example 4

[0084] Adopting such Figure 1 The system shown has a Ni-YSZ hydrogen electrode in the SOEC fuel cell stack. An external heating box 9 is provided around the SOEC fuel cell stack. The heating box 9 comprises an aluminosilicate plate and a nano-insulation layer arranged sequentially from the inside out. Heating wires are embedded in the inner surface of the aluminosilicate plate, with a distance of 20 mm between the heating wires and the outer surface of the aluminosilicate plate. The aluminosilicate plate is 30 mm thick and has a strength of 10 MPa. The nano-insulation layer uses DRT10 nano-aerogel insulation material produced by Guangdong Elisheng Technology Co., Ltd., and has a thickness of 70 mm.

[0085] Hydrogen protective gas enters hydrogen protective gas heat exchanger 1, and feedwater enters steam generator 2. The steam flow rate is 100 L / min, and the hydrogen protective gas flow rate is 20 L / min. After heat exchange, the hydrogen temperature reaches 120℃, and the steam output temperature from the steam generator is 125℃. After thorough mixing in mixer 3, the mixture enters hydrogen electrode side heat exchanger 4, where the temperature reaches 480℃. After high-temperature preheating, the mixed gas temperature reaches 760℃ and enters the hydrogen electrode inlet of SOEC stack 8. Air supplied by air pressure enters oxygen electrode side preheater 7, where the temperature reaches 450℃. After preheating to 750℃, the air enters oxygen electrode inlet of SOEC stack 8.

[0086] The exhaust gas temperature of the hydrogen electrode and oxygen electrode is 740℃. After passing through the hydrogen electrode side heat exchanger 4 and the air heat exchanger 6 respectively, the temperature drops to 400℃. It enters the waste heat recovery heat exchanger 10, and after heat exchange with cold water, the temperature drops to 80℃. It then undergoes further heat exchange with the hydrogen protective gas heat exchanger 1, and the temperature drops to 40℃ before being sent to the feed water of the steam generator. The hydrogen production power regulator 11 can adjust the power at any time according to the fluctuation of the hydrogen production power supply, and then feed back to regulate the flow rate and pressure of the incoming steam and air, so that the entire system can achieve dynamic thermal balance and material balance, ensuring the safe and reliable operation of the system.

[0087] Under this condition, a combined power generation reaction occurred inside the SOEC battery stack, causing an increase in heat inside the stack, disrupting the thermal balance of the entire system, making the electrolysis reaction process unstable, and resulting in a significant decrease in electrolysis efficiency compared to Example 1, and an increase in hydrogen production energy consumption.

[0088] Example 5

[0089] Following the method of Example 1, using as follows Figure 1 The solid oxide hydrogen production system shown includes an electric stack heat box 9 consisting only of an aluminum silicate plate, with the heating wire attached to the inner surface of the aluminum silicate plate, which has a thickness of 100 mm.

[0090] Under this condition, due to the poor insulation of the stack heat box 9, the power consumption of the entire system increases significantly in order to maintain a constant SOEC temperature. However, the electrolysis reaction process is relatively stable. Compared with Example 1, the energy consumption for hydrogen production has increased significantly, resulting in a decrease in the overall hydrogen production efficiency.

[0091] Comparative Example 1

[0092] The method according to Example 1 differs in that a hydrogen protective gas supply device (including a hydrogen protective gas heat exchanger and a hydrogen supply device) and a mixer are not provided.

[0093] Feedwater enters steam generator 2 with a steam flow rate of 100 L / min. The steam output temperature of the steam generator is 110°C. It enters the hydrogen electrode side heat exchanger 4. After heat exchange, the temperature reaches 110°C and enters the hydrogen electrode side preheater 5. After high-temperature preheating, the temperature of the mixed gas reaches 750°C and enters the hydrogen electrode inlet of SOEC stack 8. Air supplied by air pressure enters the oxygen electrode side preheater 7 after heat exchange in air heat exchanger 6, reaching a temperature of 450°C. After preheating to 750°C, the air enters the oxygen electrode inlet of SOEC stack 8.

[0094] The exhaust gas temperature of the hydrogen electrode and oxygen electrode is 720℃. After passing through the hydrogen electrode side heat exchanger 4 and the air heat exchanger 6 respectively, the temperature drops to 350℃. It enters the waste heat recovery heat exchanger 10, and after being cooled by cold water, the temperature drops to 40℃ and is sent to the feed water of the steam generator.

[0095] Under this condition, the nickel electrode on the hydrogen electrode side underwent a significant oxidation reaction, resulting in a sharp decline in electrolysis efficiency. As the nickel electrode was completely oxidized, the electrolysis operation eventually ceased.

[0096] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A system for producing hydrogen from solid oxides, characterized in that, The system includes: SOEC stack (8) includes hydrogen electrode side inlet, hydrogen electrode side outlet, oxygen electrode side inlet, and oxygen electrode side outlet; The first raw material gas supply unit includes a hydrogen protective gas supply device, a steam supply device, a mixer (3), a hydrogen electrode side heat exchanger (4), and a hydrogen electrode side preheater (5); the inlet of the mixer (3) is connected to the hydrogen protective gas supply device and the steam supply device, and is used to mix the hydrogen from the hydrogen protective gas supply device and the steam from the steam supply device to obtain the first raw material gas; the feed port of the hydrogen electrode side heat exchanger (4) is connected to the outlet of the mixer (3), the heat medium inlet of the hydrogen electrode side heat exchanger (4) is connected to the hydrogen electrode side outlet of the SOEC stack (8), and is used to perform a first heat exchange between the tail gas from the hydrogen electrode side outlet and the first raw material gas; the first raw material gas outlet of the hydrogen electrode side heat exchanger (4) is connected to the inlet of the hydrogen electrode side preheater (5), and the outlet of the hydrogen electrode side preheater (5) is connected to the hydrogen electrode side inlet of the SOEC stack. The second raw material gas supply unit includes an air supply device, an air heat exchanger (6), and an oxygen electrode side preheater (7) connected in sequence. The heat medium inlet of the air heat exchanger (6) is connected to the oxygen electrode side outlet of the SOEC stack (8) for exchanging the exhaust gas from the oxygen electrode side outlet with the air from the air supply device for the second heat exchange. The air outlet of the air heat exchanger (6) is connected to the inlet of the oxygen electrode side preheater (7), and the outlet of the oxygen electrode side preheater (7) is connected to the oxygen electrode inlet of the SOEC stack.

2. The system according to claim 1, wherein, The steam supply device includes a water supply device and a steam generator (2); the hydrogen protective gas supply device includes a hydrogen supply device and a hydrogen protective gas heat exchanger (1); The system also includes a waste heat recovery heat exchanger (10); the inlet of the waste heat recovery heat exchanger (10) is connected to the medium outlet of the hydrogen electrode side heat exchanger (4) and the medium outlet of the air heat exchanger (6), respectively, and the waste heat from the medium of the hydrogen electrode side heat exchanger (4) and the air heat exchanger (6) is used to perform a third heat exchange with cold water. The hot water obtained from the third heat exchange is used to provide the water source for the steam supply device.

3. The system according to claim 2, wherein, The outlet of the waste heat recovery heat exchanger (10) is connected to the hydrogen protective gas heat exchanger (1). The hot water obtained by the waste heat recovery heat exchanger (10) is exchanged with the hydrogen of the hydrogen supply device for the fourth heat exchange. The water phase after the fourth heat exchange is sent to the water supply device to provide the water source for the steam supply device. Preferably, the hydrogen electrode of the SOEC stack is a nickel electrode, and more preferably a nickel electrode supported by yttrium oxide-stabilized zirconium oxide.

4. The system according to any one of claims 1-3, wherein, The system also includes: The heat box (9) of the SOEC stack is located outside the SOEC stack and is used to provide a constant temperature heat source for the SOEC stack. Preferably, the electric stack heating box (9) includes an aluminum silicate plate and a nano-insulation layer arranged sequentially from the inside out, and heating wires attached to or embedded in the inner surface of the aluminum silicate plate.

5. The system according to claim 4, wherein, The distance between the heating element and the outer surface of the aluminum silicate plate shall be no less than 20% of the total thickness of the aluminum silicate plate, preferably 20%-60%; Preferably, the thickness of the aluminum silicate board is such that the outer surface temperature is reduced to below 600°C after the aluminum silicate board is used for heat insulation; Preferably, the aluminum silicate plate has a thickness of 30-50 mm and a strength of not less than 10 MPa; Preferably, the distance between the heating element and the outer surface of the aluminum silicate plate is 10-20 mm; Preferably, the nano-insulation layer is selected from at least one of nano-aerogel insulation layer, nano-microporous material insulation layer, and nano-insulation board; Preferably, the thickness of the nano-insulation layer is such that the outer surface temperature is reduced to below 60°C after the nano-insulation layer has been used for heat insulation. Preferably, the thickness of the nano-insulation layer is 50-100 mm.

6. The system according to any one of claims 1-5, wherein, The system also includes a hydrogen production power regulator (11) that adjusts the flow rate and pressure of water vapor and air in the intake gas according to power feedback.

7. A method for producing hydrogen from solid oxides, characterized in that, The method is performed in the system according to any one of claims 1-6, and the method includes the following steps: (1) Hydrogen gas and water vapor are mixed in a mixer to obtain the first raw material gas; Based on the volumetric flow rate of the water vapor, the volumetric amount of hydrogen is 4-20%. (2) The first raw material gas and the tail gas from the hydrogen electrode side outlet are subjected to the first heat exchange in the hydrogen electrode side heat exchanger, and then the gas is preheated by the hydrogen electrode side preheater and sent to the hydrogen electrode side of the SOEC stack. (3) The air and the tail gas from the oxygen electrode side outlet are subjected to a second heat exchange in the air heat exchanger, and then the air is preheated by the oxygen electrode side preheater before being sent to the oxygen electrode side of the SOEC stack.

8. The method according to claim 7, wherein, Based on the volumetric flow rate of the water vapor, the volumetric amount of hydrogen is 5-8%. Preferably, the temperature of the water vapor is greater than 100°C; Preferably, step (1) includes: performing a fourth heat exchange on hydrogen in a hydrogen protective gas heat exchanger, so that the temperature of the hydrogen after heat exchange is above 100°C, and then mixing it with water vapor in a mixer.

9. The method according to claim 7 or 8, wherein, The temperature of the exhaust gas at the outlet of the hydrogen electrode side is not lower than 700°C; Preferably, the first heat exchange ensures that the temperature of the first raw material gas after heat exchange is not lower than 400°C, and more preferably 400-600°C; Preferably, the temperature of the first raw material gas after preheating by the hydrogen electrode side preheater is not lower than 750°C, and more preferably 750-800°C.

10. The method according to any one of claims 7-9, wherein, The temperature of the exhaust gas at the oxygen electrode outlet shall not be lower than 700°C; Preferably, the second heat exchange ensures that the temperature of the air after heat exchange is not lower than 400°C, and more preferably 400-600°C; Preferably, the air temperature after preheating by the oxygen electrode side preheater is not lower than 750°C, and more preferably 750-800°C.

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