SOEC hydrogen production thermal management system coupled with industrial waste heat and method thereof

Abstract

The invention relates to an SOEC hydrogen production heat management system coupled with industrial waste heat. The industrial waste heat in a first temperature interval is subjected to temperature upgrading and then stored through a first heat storage tank; industrial waste heat in the second temperature interval is directly stored through the second heat storage tank, and a double-heat-storage structure is formed; outlet pipelines of the first heat storage tank and the second heat storage tank are respectively connected with a discharging three-way valve, an outlet pipeline of the discharging three-way valve is connected with a hot end inlet of a heat exchange module, a hot end outlet of the heat exchange module is connected with an inlet of a material returning three-way valve, and an outlet pipeline of the material returning three-way valve is respectively connected with the first heat storage tank and the second heat storage tank. The invention further relates to an SOEC hydrogen production thermal management method coupled with industrial waste heat. The problems that low-temperature waste heat is difficult to use and high-temperature waste heat is wasted are solved through a double-heat-storage structure, and the problem that the pile temperature is unstable due to heat source fluctuation is solved through control of the three-way valve.

Description

Technical Field

[0001] This invention relates to hydrogen production using a high-temperature solid oxide electrolysis cell (SOEC), and more specifically to a thermal management system and method for SOEC hydrogen production coupled with industrial waste heat. Background Technology

[0002] SOEC, as a highly efficient hydrogen production technology, essentially produces hydrogen through an electrolysis reaction driven by an external direct current. The specific reaction process is as follows: water vapor is introduced into the fuel side (cathode) of the SOEC, where it is reduced to hydrogen under the influence of direct current, accompanied by the generation of oxygen ions (O2). 2- ) generates; the generated O 2- The oxygen-ion electrolyte in the SOEC migrates to the air side (anode) and is eventually oxidized at the anode to generate oxygen. This electrolysis reaction has strict requirements for operating conditions. The reaction zone and electrolyte of the SOEC need to maintain a high conductivity temperature of 600-850°C. At the same time, the system also needs to provide sufficient enthalpy for water vapor to form superheated steam. Both of these requirements depend on a continuous supply of high-temperature heat source.

[0003] From an energy balance perspective, the electrolysis process of SOEC exhibits significant heat interaction characteristics: when the electrolysis voltage is lower than the thermal neutral voltage, the system cannot meet its energy requirements through the electrolysis reaction itself and needs to absorb heat from the outside to compensate for the energy consumption of the reaction; when the electrolysis voltage is higher than the thermal neutral voltage, the system will release heat due to excessive reaction. In order to stably maintain an operating temperature of 600-850℃ and meet the enthalpy requirements of superheated steam, traditional SOEC hydrogen production systems require the configuration of independent high-temperature heating devices. The additional operation of this device not only significantly increases the overall energy consumption of the electrolysis system, but also results in the ineffective utilization of the waste heat generated by the system itself (such as the heat released when the voltage is higher than the thermal neutral voltage), forming a dual problem of high energy consumption and waste of waste heat.

[0004] To address the issues of high energy consumption and low waste heat utilization in traditional SOEC hydrogen production systems, existing technologies propose a technical approach that couples SOEC hydrogen production systems with industrial waste heat. This approach utilizes waste heat generated during industrial production to replace part or all of the energy consumption of independent high-temperature heating devices, thereby achieving the goals of waste heat resource utilization and system energy consumption reduction.

[0005] The application scenarios of this coupling approach mainly cover industrial sectors such as steel, chemicals, papermaking, and waste-to-energy plants. These sectors continuously generate a large amount of waste heat during production, and the temperature range of this waste heat is extremely wide, covering multiple temperature ranges from 40℃ (low-temperature waste heat) to 1000℃ (high-temperature waste heat). Theoretically, this can provide abundant heat source replenishment for SOEC hydrogen production systems. Based on this, existing solutions attempt to introduce industrial waste heat into SOEC hydrogen production systems through direct or simple heat exchange, in order to replace the function of traditional high-temperature heating devices and reduce the system's dependence on external energy.

[0006] Although the coupling of SOEC hydrogen production systems and industrial waste heat is theoretically feasible, existing technologies have many shortcomings in practical applications, resulting in the coupling effect falling far short of expectations. Specific shortcomings are as follows:

[0007] First, the heat source is unstable and cannot meet the continuous heating needs of SOEC.

[0008] The temperature of industrial waste heat is greatly affected by industrial production conditions (such as furnace temperature fluctuations in steel smelting and load adjustments in chemical reactions). A wide temperature range of 40-1000℃ leads to frequent fluctuations in waste heat temperature, with fluctuations reaching tens or even hundreds of degrees Celsius. SOEC hydrogen production systems have extremely high requirements for the stability of heat source temperature. SOEC can operate in a temperature range of approximately 600-850℃, but the operating temperature needs to be controlled within a small fluctuation range during stable operation (excessive temperature fluctuations can lead to uneven thermal stress inside the stack and decreased electrolyte conductivity). Existing solutions lack effective waste heat temperature buffering and regulation mechanisms, failing to convert fluctuating industrial waste heat into a stable high-temperature heat source. Consequently, SOEC hydrogen production systems struggle to obtain a continuous and stable heat supply, severely impacting the operational stability of the stack.

[0009] Secondly, the utilization efficiency of waste heat in multiple temperature zones is low, and low-temperature waste heat cannot be directly applied.

[0010] Existing solutions lack a gradient adaptation design for the utilization of waste heat in multiple temperature zones of industry: On the one hand, for high-temperature waste heat around 1000℃, existing solutions simply introduce it into the SOEC system through heat exchange, without considering the differences in heat demand at different operating stages of SOEC (start-up, stable operation, shutdown), resulting in high-temperature waste heat not being efficiently distributed to the stages that need the most heat, and some high-temperature waste heat being directly discharged due to supply and demand mismatch; on the other hand, for low-temperature waste heat of 40-150℃, its temperature is far below the SOEC's operating temperature requirement of 600-850℃, and existing solutions lack effective low-temperature waste heat upgrading technology (i.e., technology to convert low-temperature heat sources into high-temperature heat sources), resulting in a large amount of low-temperature waste heat not being directly used by the SOEC hydrogen production system, but only being discharged as waste heat, causing serious waste of waste heat resources.

[0011] Third, the waste heat from the SOEC fuel cell stack exhaust gas was not recovered, further reducing the overall waste heat utilization rate.

[0012] Current coupling schemes only focus on the input of industrial waste heat to SOEC, neglecting the waste heat generated by the SOEC hydrogen production system itself. During operation (especially in the stable operation phase), SOEC stacks generate exhaust gases containing waste heat (such as unreacted water vapor exhaust gas from the cathode and oxygen exhaust gas from the anode). The temperature of these exhaust gases is usually maintained at several hundred degrees Celsius, possessing certain heat recovery value. However, current schemes do not include corresponding exhaust gas waste heat recovery and reuse mechanisms, resulting in this part of the exhaust gas waste heat being directly discharged from the system, further reducing the overall waste heat utilization rate of the entire coupling system.

[0013] Fourth, the system has a low degree of coupling, making it difficult to maintain thermal equilibrium.

[0014] In existing solutions, there is a lack of deep integration between the heat exchange and transmission of industrial waste heat and the heat demand of the SOEC hydrogen production system. On the one hand, the waste heat exchange devices (such as heat exchangers) and the heat demand of the SOEC stack are not linked for control, making it impossible to adjust the heat exchange capacity according to the real-time heat demand of the stack. On the other hand, existing solutions lack effective heat storage devices (or the heat storage devices are not sufficiently coupled with the heat exchange system), making it impossible to store heat when there is an excess of industrial waste heat or release heat when there is a shortage, resulting in difficulty in maintaining the thermal balance of the entire system. These problems ultimately manifest as large temperature fluctuations in the SOEC stack, which not only affect the lifespan of the stack but also lead to a decrease in electrolysis reaction efficiency due to temperature instability, further increasing system power consumption. Summary of the Invention

[0015] To address the issues of underutilization of industrial waste heat resource value and unstable heat source in SOEC hydrogen production systems in existing technologies, this invention aims to provide an SOEC hydrogen production thermal management system and method coupled with industrial waste heat.

[0016] The SOEC hydrogen production thermal management system coupled with industrial waste heat according to the present invention includes an industrial waste heat conveying device, serving as the waste heat source of the system, outputting industrial waste heat in a first temperature range (e.g., 40-150°C) and a second temperature range (e.g., 700-1000°C), wherein the temperature in the first temperature range is lower than that in the second temperature range; a heat pump module for temperature boosting of the industrial waste heat in the first temperature range; and a heat storage module, including a first heat storage tank and a second heat storage tank. The output end of the industrial waste heat conveying device is connected to the heat pump module via a first branch pipe to convey the industrial waste heat in the first temperature range. The output end of the heat pump module is sealed to the first heat storage tank to store the temperature-boosted heat through the first heat storage tank. The output end of the industrial waste heat conveying device is connected to the second branch pipe. The system is sealed to a second thermal storage tank to transport industrial waste heat in the second temperature range and directly store the industrial waste heat in the second temperature range through the second thermal storage tank, forming a dual thermal storage structure; an SOEC hydrogen production module is used to complete the hydrogen production reaction and recover the waste heat from the tail gas; a heat exchange module, which is a multi-flow heat exchanger, is used to transfer the heat from the thermal storage module to the SOEC hydrogen production module to provide the high-temperature conditions required for SOEC hydrogen production; the thermal storage module also includes a discharge three-way valve and a return three-way valve. The outlet pipes of the first and second thermal storage tanks are respectively connected to the discharge three-way valve, the outlet pipe of the discharge three-way valve is connected to the hot end inlet of the heat exchange module, the hot end outlet of the heat exchange module is connected to the inlet of the return three-way valve, and the outlet pipe of the return three-way valve is respectively connected back to the first and second thermal storage tanks; the cold end of the heat exchange module is connected to the SOEC hydrogen production module.

[0017] In a preferred embodiment, the heat pump module includes an evaporator, a primary compressor, a heat exchanger, a gas-liquid separator, and a secondary compressor. The evaporator uses industrial waste heat in a first temperature range to heat the coolant, causing it to evaporate into a gaseous state. The primary compressor compresses the gaseous coolant to form a first-temperature-increasing coolant. The heat exchanger recovers a portion of the heat from the first-temperature-increasing coolant for preheating the first heat storage tank. The remaining first-temperature-increasing coolant is cooled and enters the gas-liquid separator to separate the liquid components. The secondary compressor further compresses the gaseous coolant after separating the liquid components to form a second-temperature-increasing coolant. The second-temperature-increasing coolant enters the first heat storage tank to store the heat after the temperature increase.

[0018] In a preferred embodiment, the first heat storage tank is filled with a medium-temperature phase change heat storage material to store the heat of 200-380°C after the heat pump is upgraded. The design phase change temperature range of the medium-temperature phase change heat storage material is 300-380°C, and the heat release range of the first heat storage tank is between 290-380°C, serving as a preheating heat source during the SOEC start-up phase and a regulating heat source during the operation phase.

[0019] In a preferred embodiment, the second heat storage tank is filled with high-temperature phase change heat storage material to directly store industrial high-temperature waste heat of 700-1000℃, providing a core high-temperature heat source of 600-850℃ for the stable operation of the fuel cell stack module, and receiving the recovered waste heat from the fuel cell stack exhaust gas.

[0020] In a preferred embodiment, the flow area ratio between the first heat storage tank branch and the second heat storage tank branch is changed by adjusting the discharge three-way valve and the return three-way valve, thereby controlling the temperature of the heat flow entering the heat exchange module.

[0021] In a preferred embodiment, the cold end of the heat exchange module includes a separate deionized water cold end channel and an air cold end channel. The deionized water cold end channel is used to vaporize deionized water into superheated steam at 600-850°C, and the air cold end channel is used to heat the anode air to 600-850°C.

[0022] In a preferred embodiment, the SOEC hydrogen production module includes a fuel cell module for electrolytic hydrogen production at high temperatures. Its cathode inlet is connected to the deionized water-cooled end channel outlet of the heat exchange module, and its anode inlet is connected to the air-cooled end channel outlet of the heat exchange module. Superheated steam and air at 600-850°C enter the cathode and anode of the fuel cell module respectively for electrolysis to produce hydrogen and oxygen.

[0023] In a preferred embodiment, the SOEC hydrogen production module further includes a tail gas heat exchanger, which is used to recover the waste heat of the 400-600°C tail gas discharged from the fuel cell stack and recharge it to the second heat storage tank.

[0024] In a preferred embodiment, the SOEC hydrogen production module further includes an air compressor, a water tank, and a mixer. The air compressor provides clean compressed air to the anode of the fuel cell stack, which is heated by the heat exchange module and then enters the fuel cell stack. The water tank provides high-purity deionized water to the cathode of the fuel cell stack, which is heated and vaporized by the heat exchange module and then mixed with circulating hydrogen in the mixer before entering the fuel cell stack.

[0025] The SOEC hydrogen production thermal management method coupled with industrial waste heat according to the present invention includes the following steps: an industrial waste heat conveying device sends waste heat in a first temperature range into a heat pump module through a first branch pipe, and sends waste heat in a second temperature range directly into a second heat storage tank through a second branch pipe; the heat pump module performs two-stage upgrading of the waste heat in the first temperature range before sending it into the first heat storage tank for storage; based on the temperature requirements of different stages of electrolytic reactor operation, the heat output ratio of the first heat storage tank and the second heat storage tank is adjusted through a discharge three-way valve and a return three-way valve. A stable heat is supplied to the heat exchange module, wherein the different stages include a preheating stage, a heating stage, a constant temperature stage, and a cooling stage; the heat exchange module heats air and deionized water respectively, wherein the heated air is sent to the anode of the fuel cell module, and the deionized water is heated and vaporized into water vapor, which is mixed with circulating hydrogen in a mixer to form water vapor-hydrogen mixed steam. This mixed steam is heated and sent to the cathode of the fuel cell module, where it undergoes an electrolytic reaction to produce oxygen and hydrogen. The exhaust gas produced by the reaction is recycled for waste heat through an exhaust gas heat exchanger and then recharged to the second heat storage tank.

[0026] This invention solves the problems of unusable low-temperature waste heat and wasted high-temperature waste heat through a dual heat storage design using a second heat storage tank (directly storing, for example, waste heat at 700-1000℃), a heat pump upgrade, and a first heat storage tank (storing, for example, waste heat at 200-380℃). Furthermore, this invention uses a three-way valve to control the ratio of medium-temperature and high-temperature heat, ensuring that the hot-end temperature of the heat exchange module remains stable at 600-850℃, thus resolving the problem of unstable fuel cell stack temperature caused by heat source fluctuations. Attached Figure Description

[0027] Figure 1 This is a process flow diagram of an SOEC hydrogen production thermal management system coupled with industrial waste heat according to a preferred embodiment of the present invention. Detailed Implementation

[0028] The preferred embodiments of the present invention are given below with reference to the accompanying drawings and described in detail.

[0029] like Figure 1 As shown, the SOEC hydrogen production thermal management system coupled with industrial waste heat according to the present invention includes an industrial waste heat conveying device 1, a heat pump module 2-6, and a heat storage module 7-10. The heat storage module 7-10 includes a first heat storage tank 9 (medium-temperature heat storage tank) and a second heat storage tank 10 (high-temperature heat storage tank). The industrial waste heat conveying device 1 is the waste heat source of the system. Based on the waste heat temperature range, the output end of the industrial waste heat conveying device 1 is connected to the heat pump module 2-6 via a first branch pipe. The output end of the heat pump module 2-6 is sealed to the first heat storage tank 9, and the output end of the industrial waste heat conveying device 1 is sealed to the second heat storage tank 10 via a second branch pipe, forming a dual heat storage structure of low-temperature upgraded heat storage and high-temperature direct heat storage.

[0030] Heat pump modules 2-6 are temperature-raising units for low-temperature waste heat (40-150℃), consisting of an evaporator 2, a primary compressor 3 (primary heat pump), a heat exchanger 4, a gas-liquid separator 5, and a secondary compressor 6 (secondary heat pump). In the evaporator 2, the industrial low-temperature waste heat in the first branch pipe of the industrial waste heat transfer device 1 heats the coolant, causing it to evaporate from a liquid to a gaseous state, completing the initial absorption of the low-temperature waste heat. In the primary compressor 3, the gaseous coolant can be compressed through dynamic load adjustment to form a heated coolant (150-180℃), achieving the first temperature upgrade of the low-temperature waste heat. In the heat exchanger 4, a portion of the heat from the heated coolant is recovered for preheating the first heat storage tank 9, while the remaining heated coolant is cooled to a low-temperature coolant (130-150℃). In the gas-liquid separator 5, a small amount of liquid components in the low-temperature coolant is separated, ensuring that the coolant entering the secondary compressor 6 is purely gaseous. In the secondary compressor 6, the gaseous coolant can be further compressed through dynamic load adjustment to form a heated coolant (200-380℃, ideal upgrade temperature is 300-360℃), realizing a second temperature upgrade of low-temperature waste heat.

[0031] The first heat storage tank 9 is sealed to the output end of the second-stage compressor 6. The tank is filled with a medium-temperature phase change heat storage material to receive and store the medium-temperature heat (200-380℃) after the heat pump upgrade. This medium-temperature phase change heat storage material includes a phase change substrate and a supporting carrier. The phase change substrate is selected from one or more of sodium nitrate, potassium nitrate, sodium nitrite, potassium chloride, and magnesium chloride. The supporting carrier is selected from one or more of SiO2, diatomaceous earth, silica fume, mullite, corundum, and kaolin. The composition ratio of the phase change substrate and the mass ratio of the supporting carrier can be adjusted based on a designed phase change temperature range of 300-380℃ (preferably 290-380℃), with a heat release range of 290-380℃ (preferably 350-380℃). To achieve efficient heat transfer between the medium-temperature phase change thermal storage material and the external environment, the first thermal storage tank 9 completes heat exchange through a heat exchange medium, which is a fluorinated salt, chloride salt, or heat transfer oil. This medium fills the heat release circuit and the waste heat recovery circuit of the thermal storage device. The heat exchange medium exchanges heat with the thermal storage material through the peripheral voids of the porous medium. Combined with the compressor's dynamic load adjustment capability and the selection of the medium-temperature phase change thermal storage material, the first thermal storage tank 9 can stably store high-grade heat at 350-380℃. This heat serves as a preheating heat source (for air and steam preheating) during the SOEC start-up phase and a regulating heat source during the operation phase. Specifically, after mixing with the discharge from the thermal storage tank 10, it increases or decreases the heat entering the heat exchanger 11, ensuring that the temperature entering the heat exchanger 11 meets the thermal requirements of the fuel cell.

[0032] The second thermal storage tank 10 is filled with a high-temperature phase change thermal storage material. This high-temperature phase change thermal storage material includes a phase change substrate and a supporting carrier. The phase change substrate is selected from one or more of Li2CO3, Na2CO3, K2CO3, CaCO3, and Cu-Si alloy. The supporting carrier is selected from one or more of SiO2, diatomaceous earth, silica fume, mullite, corundum, and kaolin. The high-temperature phase change thermal storage material directly receives and stores industrial high-temperature waste heat (700-1000℃). Through the heat absorption melting and release solidification of the storage material, heat is buffered and stored, providing a core high-temperature heat source (600-850℃) for the stable operation of the fuel cell stack module 12. This avoids temperature fluctuations caused by direct heat exchange with high-temperature waste heat and simultaneously receives recovered waste heat from the fuel cell stack exhaust gas.

[0033] like Figure 1 As shown, the SOEC hydrogen production thermal management system coupled with industrial waste heat according to the present invention further includes a heat exchange module 11 and SOEC hydrogen production modules 12-15. The heat exchange module 11 is a multi-flow heat exchanger, including a hot-end channel and a cold-end channel. The hot-end channel has one inlet and one outlet interface, forming a closed-loop connection with the heat storage module 7-10 via a pipeline. The cold-end channel is divided into two independent channels, corresponding to two inlet and two outlet interfaces, respectively connected to the SOEC hydrogen production modules 12-15. The core function of the heat exchange module 11 is to achieve heat transfer: the stable high-temperature heat output from the heat storage module 7-10 flows through the hot-end channel, transferring heat through the heat exchanger wall to the media (air, deionized water) in the two independent cold-end channels, providing the required high-temperature conditions for the electrolysis reaction of the SOEC hydrogen production module 12-15 (anode air heated to 600-850℃, cathode deionized water vaporized and heated to superheated steam at 600-850℃).

[0034] In addition to the first thermal storage tank 9 and the second thermal storage tank 10 mentioned above, the thermal storage module 7-10 also includes a discharge three-way valve 7 and a return three-way valve 8. The outlet pipes of the first thermal storage tank 9 and the second thermal storage tank 10 are respectively connected to the discharge three-way valve 7. The outlet pipe of the discharge three-way valve 7 is connected to the hot end inlet of the heat exchange module 11. The hot end outlet of the heat exchange module 11 is connected to the inlet of the return three-way valve 8. The outlet pipe of the return three-way valve 8 is respectively connected back to the first thermal storage tank 9 and the second thermal storage tank 10, forming a thermal circulation path of thermal storage tank-three-way valve-heat exchanger.

[0035] Both the discharge three-way valve 7 and the return three-way valve 8 have valve bodies and valve cores made of high-temperature alloy or silicon carbide ceramic. They are equipped with electric actuators to drive the valve core rotation, changing the flow area to control the heat exchange temperature and achieve cascaded heat utilization. The common inlet of the discharge three-way valve 7 is divided into two paths: one connects to the outlet of the first heat storage tank 9 (medium-temperature branch), and the other connects to the outlet of the second heat storage tank 10 (high-temperature branch); the common outlet of the discharge three-way valve 7 is connected to the hot end inlet of the heat exchange module 11 via a pipeline. The common inlet of the return three-way valve 8 is connected to the hot end outlet of the heat exchange module 11; the common outlet of the return three-way valve 8 is divided into two paths: one returns to the return port of the first heat storage tank 9, and the other returns to the return port of the second heat storage tank 10. The valve core is driven to rotate by an electric actuator, which changes the flow area ratio between the medium-temperature branch and the high-temperature branch (e.g., during SOEC startup: the medium-temperature branch is 80% open and the high-temperature branch is 20% open; during stable operation: the medium-temperature branch is 20% open and the high-temperature branch is 80% open). This precisely controls the temperature of the heat flow entering the heat exchange module 11, ensuring that the hot end temperature of the heat exchange module 11 is stable at 600-850℃, meeting the heat demand of the fuel cell stack module 12, and solving the problem of large temperature fluctuations in the heat source in existing technologies.

[0036] SOEC hydrogen production modules 12-15 include fuel cell module 12, exhaust gas heat exchanger 13, air compressor 14, water tank 15, and mixer 16. Fuel cell module 12 (SOEC hydrogen production module) has a cathode and an anode. The cathode side is equipped with a steam inlet and a hydrogen outlet, while the anode side is equipped with an air inlet and an oxygen outlet. Its cathode inlet is connected to the deionized water-cooled end channel outlet of heat exchange module 11 via a pipe, and its cathode outlet is connected to the hydrogen exhaust gas inlet of exhaust gas heat exchanger 13 via a pipe. Its anode inlet is connected to the air-cooled end channel outlet of heat exchange module 11 via a pipe, and its anode outlet is connected to the oxygen exhaust gas inlet of exhaust gas heat exchanger 13. Fuel cell module 12 operates under stable conditions of 600-850℃: superheated steam introduced on the cathode side is reduced to generate hydrogen, and oxygen ions on the anode side undergo oxidation to generate oxygen, ultimately achieving efficient hydrogen production. The core function of exhaust gas heat exchanger 13 is to recover waste heat from the fuel cell exhaust gas. The hydrogen and oxygen exhaust gases (400-600℃) emitted from the fuel cell stack flow through the exhaust gas heat exchanger 13 for heat exchange. The heat after heat exchange is returned to the second heat storage tank 10 via a pipeline, avoiding waste caused by direct discharge of exhaust gas waste heat, and simultaneously replenishing heat for the heat storage module. The air compressor 14 provides clean compressed air required for the oxidation reaction at the fuel cell stack anode. Its outlet is connected to the air cold end channel inlet of the heat exchange module 11 via a pipeline. After being heated to 600-850℃ by the heat exchange module 11, the air enters the anode of the fuel cell stack, effectively avoiding internal temperature fluctuations caused by direct introduction of ambient temperature air, and ensuring the stability of the electrolysis reaction. Water tank 15 provides high-purity deionized water to the cathode of the fuel cell stack. Its outlet is connected to the inlet of the deionized water cooling channel of heat exchange module 11 through a pipeline. The water is heated and vaporized by heat exchange module 11 into superheated steam at 600-850°C. Since the cathode reactants in this invention are water and hydrogen, a small amount of hydrogen generated during electrolysis is introduced into mixer 16 through a circulation loop. After being fully mixed with the superheated steam in mixer 16, water vapor-hydrogen mixed steam is formed and enters the cathode of the fuel cell stack. By recycling the hydrogen generated by electrolysis, the proportion of reactants required for the cathode reaction is ensured, and the raw material utilization rate is improved.

[0037] In summary, this invention addresses the shortcomings of existing technologies when coupling industrial waste heat with SOEC hydrogen production systems, such as unstable high-temperature waste heat supply, difficulty in utilizing low-temperature waste heat, low overall waste heat utilization rate, and large temperature fluctuations in the fuel cell stack. Through a core design that integrates a two-stage heat pump upgrade, phase change thermal storage and heat exchange, and high-temperature direct storage, it constructs a cascaded heat exchange pipeline with medium-temperature and high-temperature dual thermal storage. This enables the gradient energy utilization of industrial waste heat and fuel cell stack reaction waste heat, providing a stable and reliable high-temperature heat source for SOEC hydrogen production.

[0038] The core operating logic of the system is as follows: the intermediate-temperature thermal storage tank 9, as the primary superheating unit, mainly undertakes the preheating of steam and air during the SOEC startup phase, or serves as the regulating heat source for the high-temperature thermal storage tank 10, coordinating and regulating the heat exchange supply to the heat exchange module 11; the high-temperature thermal storage tank 10, as the secondary superheating module, directly stores industrial high-temperature waste heat (700-1000℃) to ensure the core heat requirements for the stable operation of the stack module 12. The system can flexibly switch between the intermediate-temperature and high-temperature thermal storage modes through three-way valves 7 and 8 according to the temperature requirements of different stages of SOEC startup, operation, and shutdown (preheating stage, heating stage, isothermal stage, and cooling stage), precisely adjusting the output ratio of the two heat sources and effectively reducing temperature fluctuations at the stack front. Meanwhile, during the stable operation phase of the fuel cell stack module, the waste heat from the 400-600℃ exhaust gas discharged from the fuel cell stack is recovered by the exhaust gas heat exchanger 13 and then recharged into the high-temperature heat storage tank 10, forming a closed-loop thermal management system of waste heat collection, utilization and recovery. This system can store heat when there is an excess of waste heat supply and release heat when there is a shortage, maintaining the thermal balance of the system and further improving the utilization rate of waste heat.

[0039] Compared to existing technologies, this system offers significant advantages: Through a gradient design that combines direct storage of high-temperature waste heat with on-demand heat release and upgraded utilization of low-temperature waste heat via heat pumps, it solves the problems of unusable low-temperature waste heat and wasted high-temperature waste heat; with the help of thermal storage buffers and precise control via three-way valves, it enhances the system's dynamic response capability, avoids internal thermal shock to the fuel cell stack, and ensures stable operating temperatures of 600-850℃; the closed-loop thermal management mode significantly reduces the system's dependence on external heating, reducing unit hydrogen production power consumption and maximizing the utilization of industrial waste heat and fuel cell stack reaction waste heat, thus significantly improving the energy efficiency and operational stability of the entire coupled system.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A SOEC hydrogen production thermal management system coupled with industrial waste heat, characterized in that, include: An industrial waste heat conveying device (1) serves as the waste heat source of the system, outputting industrial waste heat in a first temperature range and a second temperature range, wherein the temperature in the first temperature range is lower than that in the second temperature range. A heat pump module is used to upgrade the temperature of industrial waste heat in the first temperature range; The heat storage module includes a first heat storage tank (9) and a second heat storage tank (10). The output end of the industrial waste heat conveying device (1) is connected to the heat pump module through a first branch pipe to convey industrial waste heat in the first temperature range. The output end of the heat pump module is sealed to the first heat storage tank (9) to store the heat after temperature upgrade through the first heat storage tank (9). The output end of the industrial waste heat conveying device (1) is sealed to the second heat storage tank (10) through a second branch pipe to convey industrial waste heat in the second temperature range and directly store the industrial waste heat in the second temperature range through the second heat storage tank (10), forming a dual heat storage structure. SOEC hydrogen production module is used to complete the hydrogen production reaction and recover waste heat from the tail gas. The heat exchange module (11) is a multi-stream heat exchanger used to transfer the heat from the heat storage module to the SOEC hydrogen production module to provide the high-temperature conditions required for SOEC hydrogen production. The thermal storage module also includes a discharge three-way valve (7) and a return three-way valve (8). The outlet pipes of the first thermal storage tank (9) and the second thermal storage tank (10) are respectively connected to the discharge three-way valve (7). The outlet pipe of the discharge three-way valve (7) is connected to the hot end inlet of the heat exchange module (11). The hot end outlet of the heat exchange module (11) is connected to the inlet of the return three-way valve (8). The outlet pipe of the return three-way valve (8) is respectively connected back to the first thermal storage tank (9) and the second thermal storage tank (10). The cold end of the heat exchange module (11) is connected to the SOEC hydrogen production module.

2. The SOEC hydrogen production thermal management system coupled with industrial waste heat according to claim 1, characterized in that, The heat pump module includes an evaporator (2), a primary compressor (3), a heat exchanger (4), a gas-liquid separator (5), and a secondary compressor (6). The evaporator (2) uses industrial waste heat in the first temperature range to heat the coolant and make it evaporate into a gaseous state. The primary compressor (3) compresses the gaseous coolant to form a first heating coolant. The heat exchanger (4) recovers part of the heat from the first heating coolant for preheating the first heat storage tank (9). The remaining first heating coolant is cooled and enters the gas-liquid separator (5) to separate the liquid components. The secondary compressor (6) further compresses the gaseous coolant after separating the liquid components to form a second heating coolant. The second heating coolant enters the first heat storage tank (9) to store the heat after the temperature is upgraded.

3. The SOEC hydrogen production thermal management system coupled with industrial waste heat according to claim 1, characterized in that, The first heat storage tank (9) is filled with medium-temperature phase change heat storage material to store heat of 200-380℃ after the heat pump is upgraded. The design phase change temperature range of the medium-temperature phase change heat storage material is 300-380℃. The heat release range of the first heat storage tank is between 290-380℃, serving as a preheating heat source during the SOEC start-up phase and a regulating heat source during the operation phase.

4. The SOEC hydrogen production thermal management system coupled with industrial waste heat according to claim 1, characterized in that, The second heat storage tank (10) is filled with high-temperature phase change heat storage material, which is used to directly store industrial high-temperature waste heat of 700-1000℃, provide a core high-temperature heat source of 600-850℃ for the stable operation of the fuel cell stack module (12), and receive the recovered waste heat of the fuel cell stack tail gas.

5. The SOEC hydrogen production thermal management system coupled with industrial waste heat according to claim 1, characterized in that, By adjusting the discharge three-way valve (7) and return three-way valve (8), the flow area ratio of the first heat storage tank (9) branch and the second heat storage tank (10) branch is changed, thereby controlling the temperature of the heat flow entering the heat exchange module (11).

6. The SOEC hydrogen production thermal management system coupled with industrial waste heat according to claim 1, characterized in that, The cold end of the heat exchange module (11) includes an independent deionized water cold end channel and an air cold end channel. The deionized water cold end channel is used to vaporize deionized water into superheated steam at 600-850°C, and the air cold end channel is used to heat the anode air to 600-850°C.

7. The SOEC hydrogen production thermal management system coupled with industrial waste heat according to claim 6, characterized in that, The SOEC hydrogen production module includes a fuel cell module (12), which is used to produce hydrogen by electrolysis at high temperature. Its cathode inlet is connected to the deionized water-cooled end channel outlet of the heat exchange module (11), and its anode inlet is connected to the air-cooled end channel outlet of the heat exchange module (11). Superheated steam and air at 600-850℃ enter the cathode and anode of the fuel cell respectively for electrolysis to produce hydrogen and oxygen.

8. The SOEC hydrogen production thermal management system coupled with industrial waste heat according to claim 6, characterized in that, The SOEC hydrogen production module also includes a tail gas heat exchanger (13), which is used to recover the waste heat of the 400-600℃ tail gas discharged from the fuel cell stack and recharge it to the second heat storage tank (10).

9. The SOEC hydrogen production thermal management system coupled with industrial waste heat according to claim 1, characterized in that, The SOEC hydrogen production module also includes an air compressor (14), a water tank (15), and a mixer (16). The air compressor (14) provides clean compressed air to the anode of the fuel cell stack, which is heated by the heat exchange module (11) and then enters the fuel cell stack. The water tank (15) provides high-purity deionized water to the cathode of the fuel cell stack, which is heated and vaporized by the heat exchange module (11) and then mixed with circulating hydrogen in the mixer (16) before entering the fuel cell stack.

10. A method for SOEC hydrogen production thermal management based on the system according to any one of claims 1-9, coupled with industrial waste heat, characterized in that, Includes the following steps: The industrial waste heat conveying device (1) sends the waste heat in the first temperature range into the heat pump module through the first branch pipe, and sends the waste heat in the second temperature range directly into the second heat storage tank (10) through the second branch pipe. The heat pump module performs two-stage upgrading of the waste heat in the first temperature range and then sends it to the first heat storage tank (9) for storage. Based on the temperature requirements of different stages of the operation of the electrolytic reactor, the heat output ratio of the first heat storage tank (9) and the second heat storage tank (10) is adjusted by the discharge three-way valve (7) and the return three-way valve (8) to supply stable heat to the heat exchange module (11). The different stages include the preheating stage, the heating stage, the constant temperature stage and the cooling stage. The heat exchange module (11) heats air and deionized water respectively. The air is heated and sent to the anode of the fuel cell module (12). The deionized water is heated and vaporized into water vapor, which is mixed with circulating hydrogen in the mixer (16) to form water vapor-hydrogen mixed steam. The mixed steam is heated and sent to the cathode of the fuel cell module (12). In the fuel cell, oxygen and hydrogen are generated by electrolysis. The tail gas generated by the reaction is recovered by the tail gas heat exchanger (13) and recharged to the second heat storage tank (10).

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