SOFC power generation system

Abstract

The invention relates to an SOFC power generation system which comprises a heating furnace, an electric pile, a fuel supply device, a combustion device and an air supply device. The electric pile is installed in the heating furnace and used for generating electric energy. And the fuel supply device is connected with a fuel inlet of the electric pile. Two ends of the combustion device are respectively connected with the heating furnace and a fuel outlet of the electric pile, combustible waste gas discharged from the fuel outlet is combusted in the combustion device and generates high-temperature flue gas, and the high-temperature flue gas is used for heating the heating furnace. The air supply device is used for inputting air to the galvanic pile and comprises a spiral pipe group, the spiral pipe group is spirally wound around the galvanic pile, one end of the spiral pipe group is communicated with an air source, and the other end of the spiral pipe group is connected with an air inlet of the galvanic pile. The whole spiral pipe group is wound around the galvanic pile, on one hand, the temperature of the galvanic pile can be adjusted, heat energy generated by the galvanic pile can be utilized, on the other hand, an installation space does not need to be independently designed for the spiral pipe group, the whole structure is simplified, and the design difficulty is reduced.

Description

Technical Field

[0001] This invention relates to the field of power equipment technology, and more particularly to an SOFC power generation system. Background Technology

[0002] SOFC (Solid Oxide Fuel Cell) is a power generation device that uses an electrochemical reaction. It boasts high power generation efficiency, and its reaction products are primarily water and carbon dioxide, resulting in minimal environmental pollution. Therefore, it holds great promise as a clean energy source. The SOFC power generation system reforms fuel into hydrogen at high temperatures. The hydrogen ionizes in the fuel cell stack, forming hydrogen ions that combine with oxygen ions from the air at the cathode to generate water, thus releasing electrical energy. Related technologies include a fuel cell stack for the electrochemical reaction, a fuel supply system for supplying fuel to the stack, and an air supply system for supplying air to the stack. During stack operation, the ambient temperature needs to be maintained between 700 and 750°C. Therefore, the air entering the stack needs to be preheated to a set temperature to prevent large temperature fluctuations caused by directly introducing low-temperature air.

[0003] Existing technologies have the following shortcomings: In power generation processes using ammonia as fuel, the front section of the fuel cell stack still involves ammonia cracking accompanied by endothermic reaction, while the rear section mainly involves the reaction of hydrogen and oxygen ions accompanied by exothermic reaction. This leads to significant temperature differences within the fuel cell stack, affecting its stability. Furthermore, a matching air preheating device is required to heat the air entering the fuel cell stack. Therefore, it is necessary to reserve installation space and a heat source supply for the corresponding air preheating device in the system, increasing the complexity of the system design. Summary of the Invention

[0004] The purpose of this invention is to propose an SOFC power generation system with high integration, which is conducive to simplifying structural design, and can also regulate the temperature of the fuel cell stack, thereby improving operational stability.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A SOFC power generation system is provided, comprising:

[0007] Heating furnace;

[0008] An electric fuel cell stack, installed inside the heating furnace, the electric fuel cell stack being used to generate electrical energy;

[0009] A fuel supply device is connected to the fuel inlet of the fuel cell stack and is used to supply ammonia fuel to the fuel cell stack.

[0010] A combustion device is provided, with its two ends connected to the fuel outlets of the heating furnace and the electric stack, respectively. The combustible exhaust gas discharged from the fuel outlet is burned in the combustion device to generate high-temperature flue gas, which is used to heat the heating furnace.

[0011] An air supply device is provided for supplying air to the fuel cell stack. The air supply device includes a spiral tube assembly that is spirally wound around the fuel cell stack. One end of the spiral tube assembly is connected to an air source, and the other end is connected to the air inlet of the fuel cell stack.

[0012] In one embodiment, the spiral tube assembly includes a first tube segment, a second tube segment, and a third tube segment connected in sequence. The first tube segment is connected to the air source and is located at the end of the fuel cell stack near the fuel outlet. The third tube segment is connected to the air inlet and is located at the end of the fuel cell stack near the fuel inlet. The flow velocity of the first tube segment is S1, the flow velocity of the second tube segment is S2, and the flow velocity of the third tube segment is S3, where S1 < S2 and S3 < S2.

[0013] In one embodiment, the inner diameter of the first pipe segment is greater than the inner diameter of the second pipe segment, and the inner diameter of the third pipe segment is greater than the inner diameter of the second pipe segment.

[0014] In one embodiment, the inner diameter of the first pipe segment is 12 mm, the inner diameter of the second pipe segment is 8 mm, and the inner diameter of the third pipe segment is 10 mm.

[0015] In one embodiment, the pitch of the first pipe segment is smaller than the pitch of the second pipe segment and the third pipe segment.

[0016] In one embodiment, a plurality of baffles are provided at intervals along the axial direction of the first pipe segment.

[0017] In one embodiment, a plurality of the baffles are alternately distributed on the inner walls of opposite sides of the first pipe section.

[0018] In one embodiment, the air supply device further includes a preheater disposed between the air source and the spiral tube assembly, the preheater being connected to the air outlet of the fuel cell stack to allow the preheater to exchange heat with the high-temperature air discharged from the air outlet.

[0019] In one embodiment, the fuel supply device includes an ammonia cracker installed inside the heating furnace, the outlet of which is connected to the fuel inlet of the fuel cell stack.

[0020] In one embodiment, an energy conversion device is also included, which is electrically connected to the fuel cell stack and is used to convert and store electrical energy.

[0021] The advantages of this invention compared to the prior art are:

[0022] This invention discloses an SOFC power generation system that incorporates a spiral tube assembly. The spiral tube assembly is wound in a helical shape around the fuel cell stack, allowing for heat exchange between the assembly and the stack to regulate its temperature. Simultaneously, the air input to the stack is heated within the spiral tube assembly to achieve a suitable input temperature. The entire spiral tube assembly, wound around the stack, not only regulates the stack's temperature and utilizes the heat generated, but also eliminates the need for a separate installation space for the spiral tube assembly, simplifying the overall structure and reducing design complexity. Attached Figure Description

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0024] Figure 1 This is a schematic diagram of an SOFC power generation system according to an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of a spiral tube assembly according to an embodiment of the present invention.

[0026] In the picture:

[0027] 1. Heating furnace; 11. Heating chamber; 12. Inlet flue; 13. Outlet flue; 2. Fuel stack; 21. Fuel inlet; 22. Fuel outlet; 23. Air inlet; 24. Air outlet; 3. Fuel supply device; 31. Ammonia cracker; 32. Fuel flow meter; 33. Fuel input pipeline; 34. Fuel gas source; 4. Combustion device; 41. Burner; 42. Fuel output pipeline; 5. Air supply device; 51. Spiral tube assembly; 511. First section; 512. Second section; 513. Third section; 514. Baffle; 52. Air flow meter; 53. Blower; 54. Air exhaust pipeline; 6. Power conversion device. Detailed Implementation

[0028] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0029] like Figure 1 and Figure 2As shown, the present invention provides an SOFC power generation system, including a heater 1, a fuel cell stack 2, a fuel supply device 3, a combustion device 4, and an air supply device 5. The heater 1 forms a heating chamber 11, the temperature of which is maintained at 700–800°C, providing a suitable ambient temperature for the operation of the SOFC power generation system. The fuel cell stack 2 is installed within the heating chamber 11 and is used to generate electrical energy. The fuel cell stack 2 is a prior art technology, comprising several stacked anode and cathode plates. Fuel gas and air undergo an electrochemical reaction inside the fuel cell stack 2 to generate electrical energy; the specific structure and working principle of the fuel cell stack 2 will not be described in detail here. Vertically, the top of the fuel cell stack 2 has a fuel inlet 21 and an air inlet 23. The fuel inlet 21 is used to input fuel gas into the fuel cell stack 2, and the air inlet 23 is used to input air into the fuel cell stack 2. The bottom of the fuel cell stack 2 has a fuel outlet 22 and an air outlet 24. The reacted fuel gas is discharged through the fuel outlet 22, and the reacted air is discharged through the air outlet 24. Fuel supply device 3 is used to input fuel gas into fuel cell stack 2. The fuel gas is ammonia fuel, i.e., ammonia gas. Fuel supply device 3 is connected to fuel inlet 21 of fuel cell stack 2. Combustion device 4 is used to generate heat. One end of combustion device 4 is connected to heater 1, and the other end is connected to fuel outlet 22 of fuel cell stack 2. Combustible exhaust gas discharged from fuel outlet 22 is burned in combustion device 4 to generate high-temperature flue gas. The high-temperature flue gas enters heater 1 and heats heating chamber 11 so that heater 1 can be maintained at a suitable temperature. Air supply device 5 is used to input air into fuel cell stack 2. Air supply device 5 includes a spiral tube assembly 51. The spiral tube assembly 51 is spiral-shaped and is coiled around fuel cell stack 2, i.e., fuel cell stack 2 passes through the inner side of spiral tube assembly 51. One end of spiral tube assembly 51 is connected to air source, and the other end is connected to air inlet 23 of fuel cell stack 2. An air source introduces air into the fuel cell stack 2 through a spiral tube assembly 51. The spiral tube assembly 51 is used to heat the air to a suitable temperature so that the temperature of the air entering the fuel cell stack 2 matches the operating temperature inside the fuel cell stack 2, thus avoiding the impact of temperature differences on the normal operation of the fuel cell stack 2.

[0030] Understandably, when using ammonia as a fuel gas in an SOFC power generation system, the ammonia must first undergo cracking treatment to produce hydrogen and nitrogen. The mixed fuel gas formed by ammonia, hydrogen, and nitrogen is input into the fuel cell stack 2 through fuel inlet 21. Air is input into the fuel cell stack 2 through air inlet 23. In the fuel cell stack 2, hydrogen enters the anode plate for an electron-loss oxidation electrochemical reaction, while air enters the cathode plate for an electron-receiving reduction reaction. By incorporating a spiral tube assembly 51, which is spirally coiled around the fuel cell stack 2, heat exchange can be achieved between the spiral tube assembly 51 and the fuel cell stack 2, thus regulating the temperature of the fuel cell stack 2. Simultaneously, the air input into the fuel cell stack 2 is heated within the spiral tube assembly 51 to achieve a suitable input temperature. The entire spiral tube assembly 51, coiled around the fuel cell stack 2, not only regulates the temperature of the fuel cell stack 2 and utilizes the heat energy generated by the fuel cell stack 2, but also eliminates the need for separate installation space for the spiral tube assembly 51, simplifying the overall structure and reducing design complexity.

[0031] Specifically, the heating furnace 1 is also equipped with an electric heater. During the startup phase of the fuel cell stack 2, the electric heater generates heat energy to keep the stack 2 within a suitable operating temperature range. After the fuel cell stack 2 has been running for a period of time, when the combustion of its exhaust combustible gas and its own heat release can provide sufficient heat energy, the electric heater can be turned off. The combustion device 4 includes a burner 41 and a fuel output pipe 42. The fuel outlet 22 of the fuel cell stack 2 is connected to the burner 41 through the fuel output pipe 42. The fuel gas after reaction in the fuel cell stack 2 is transported to the burner 41 for combustion through the fuel output pipe 42. The inlet end of the heating furnace 1 is provided with an inlet flue 12, and the outlet end of the heating furnace 1 is provided with an outlet flue 13. The burner 41 is connected to the inlet end of the heating furnace 1 through the inlet flue 12. The high-temperature flue gas generated after combustion in the burner 41 enters the heating furnace 1 through the inlet flue 12. After participating in heat exchange, the high-temperature flue gas is discharged through the outlet flue 13. In this embodiment, the residual combustible gas after the combustion gas participates in the electrochemical reaction in the fuel cell stack 2 enters the burner 41 for combustion, providing heat energy for the heating furnace 1. This is beneficial for the recovery and utilization of the combustion gas and saves energy.

[0032] Specifically, the helical tube assembly 51 is made of a nickel-based high-temperature alloy, such as Inconel 625, to give it excellent high-temperature oxidation resistance and creep resistance, ensuring reliable operation of the helical tube assembly 51 in a high-temperature environment of approximately 550°C. The helical tube assembly 51 includes a first tube section 511, a second tube section 512, and a third tube section 513 connected in sequence. The first tube section 511 is connected to an air source and is located at the end of the fuel cell stack 2 near its fuel outlet 22. The third tube section 513 is connected to an air inlet 23 and is located at the end of the fuel cell stack 2 near its fuel inlet 21. This structure allows air to flow along the helical tube assembly 51 from the fuel outlet 22 end of the fuel cell stack 2 towards the fuel inlet 21 end. The air velocity varies in different sections of the spiral tube assembly 51: S1 in the first section 511, S2 in the second section 512, and S3 in the third section 513, with S1 < S2 and S3 < S2. This varying air velocity results in different heat exchange efficiencies in each section, thus regulating the temperature of different areas of the fuel cell stack 2. Since the fuel gas entering the fuel cell stack 2 contains ammonia, nitrogen, and hydrogen, the ammonia continues to undergo a cracking reaction upon entering the stack, absorbing some heat energy. At the end of the fuel cell stack 2 near the fuel outlet 22, all hydrogen ions react with oxygen ions to release heat energy. This leads to a relatively higher temperature near the fuel outlet 22 and a relatively lower temperature near the fuel inlet 21. Therefore, by setting the air velocity S1 in the first section 511 to be less than the air velocity S2 in the second section 512, the air velocity near the fuel outlet 22 is slowed, promoting heat absorption in that area. The flow velocity in the second pipe section 512, located in the central region, is relatively high. Since the central region of the fuel cell stack 2 has a relatively low temperature due to the heat absorption from ammonia cracking, increasing the flow velocity in the second pipe section 512 reduces the amount of heat absorbed by the air in this region. Conversely, reducing the flow velocity in the third pipe section 513 acts as a buffer for the air, lowering its velocity when entering the fuel inlet 21 and preventing excessively high air velocity from causing mechanical and thermal shocks to the interior of the fuel cell stack 2.

[0033] Specifically, the inner diameter of the first pipe section 511 is larger than that of the second pipe section 512, and the inner diameter of the third pipe section 513 is larger than that of the second pipe section 512. By setting different inner diameters for each pipe section in the spiral tube assembly 51, the air velocity in each pipe section is controlled. For example, the inner diameter of the first pipe section 511 is 12 mm, the inner diameter of the second pipe section 512 is 8 mm, and the inner diameter of the third pipe section 513 is 10 mm. The larger the inner diameter, the lower the air velocity; the smaller the inner diameter, the higher the air velocity. It can be seen that in this embodiment, the air velocity in each pipe section is S1 < S3 < S2. Of course, in practical applications, the flow velocity of each pipe section can be comprehensively designed based on factors such as the thermal conductivity of the material, the initial air temperature, and the heat exchange efficiency.

[0034] Specifically, the pitch of the first tube segment 511 is smaller than that of the second tube segment 512 and the third tube segment 513. The helical tube assembly 51 is helical, and the pitch of the helical tube assembly 51 corresponds to the density of its distribution. It should be noted that the structure of the helical tube assembly 51 is similar to a spring; therefore, the meaning of pitch here can be directly referred to the geometric definition of a spring. The smaller pitch of the first tube segment 511 compared to the second and third tube segments 512 and 513 results in a relatively dense distribution of the first tube segment 511, while the second and third tube segments 512 and 513 are relatively sparsely distributed. This structure is beneficial for increasing the heat exchange surface near the fuel outlet 22 region, promoting the absorption of heat energy by the helical tube assembly 51 in the region corresponding to the fuel outlet 22. It also helps to reduce the heat exchange surface near the fuel inlet 21 region, reducing the absorption of heat energy by the helical tube assembly 51 in the region corresponding to the fuel inlet 21. Ultimately, this reduces the temperature difference between the regions of the fuel stack 2 near the fuel outlet 22 and near the fuel inlet 21. In an optional embodiment, the pitch of each pipe segment gradually increases from the first pipe segment 511 to the third pipe segment 513. Correspondingly, the gap ratio of the first pipe segment 511 is set to 10%, the gap ratio of the second pipe segment 512 is set to 12%, and the gap ratio of the third pipe segment 513 is set to 14%. The gap ratio is also used to reflect the density of the distribution of the spiral pipe assembly 51; the smaller the gap ratio, the denser the distribution, and the larger the gap ratio, the sparser the distribution.

[0035] Specifically, multiple baffles 514 are installed within the first pipe section 511. Along the axial direction of the first pipe section 511 (i.e., the airflow direction), the baffles 514 are spaced apart on the inner wall of the first pipe section 511. By installing the baffles 514, longitudinal vortices can be induced, disrupting the thermal boundary layer of the air and improving the air's heat transfer efficiency. To enhance the turbulence effect of the baffles 514, multiple baffles 514 are alternately distributed on opposite inner walls of the first pipe section 511. The baffles 514 also reduce the air velocity. In practical applications, by installing the baffles 514, the convective heat transfer coefficient can be increased to 120 W / (m²·K), the air residence time in the first pipe section 511 is approximately 0.08 s, and the temperature rise can reach 525–550 °C. When the air enters the second pipe section 512, the velocity increases, with the air velocity S2 reaching 15–20 m / s. Simultaneously, the length of the second pipe section 512 can be extended, thus lengthening the air flow path and allowing the air to reside in the second pipe section 512 for 0.15 seconds. The air is further heated to approximately 700°C within the second pipe section 512. Finally, the air is buffered within the third pipe section 513, and its flow velocity S3 is reduced to 8–10 m / s.

[0036] Specifically, the first pipe section 511 and the second pipe section 512 are connected by a reducing joint, and the second pipe section 512 and the third pipe section 513 are connected by a reducing joint. The reducing joint is equipped with a streamlined guide cone and a perforated plate to optimize the airflow distribution and ensure that the process of air transitioning from turbulent to laminar flow is smooth and controllable.

[0037] Specifically, the air supply device 5 also includes a preheater, an air flow meter 52, a blower 53, and air inlet and outlet pipes 54. The preheater is located between the air source and the spiral tube assembly 51, and is connected to the air outlet 24 of the fuel cell stack 2 to exchange heat with the high-temperature air discharged from the air outlet 24. The preheater preheats the air entering the spiral tube assembly 51 to increase its temperature. The air discharged from the air outlet 24 is at a higher temperature; by guiding this high-temperature air into the preheater, heat energy is recovered from the discharged high-temperature air, saving energy. The blower 53 serves as the air source, drawing outside air into the fuel cell stack 2. The blower 53 is connected to the preheater, and the preheater is connected to the spiral tube assembly 51, both via air inlet pipes. The air flow meter 52 is installed on the air inlet pipe to detect the air input volume. Air exhaust duct 54 is connected to air outlet 24 of fuel cell stack 2, and air is discharged through air exhaust duct 54. Correspondingly, a preheater is installed on air exhaust duct 54. The preheater is prior art, and it has independent low-temperature air flow channels and high-temperature air flow channels inside. Low-temperature air introduced from blower 53 enters the low-temperature air flow channel, and high-temperature air discharged from air outlet 24 enters the high-temperature air flow channel. Low-temperature air and high-temperature air exchange heat within the preheater. The specific structure and working principle of the preheater will not be described in detail here.

[0038] Specifically, the fuel supply device 3 also includes an ammonia cracker 31, a fuel flow meter 32, a fuel gas source 34, and a fuel input pipe 33. The fuel gas source 34 stores ammonia and is connected to the fuel stack 2 via the fuel input pipe 33. The fuel flow meter 32 is installed on the fuel input pipe 33 to detect the amount of fuel input. The ammonia cracker 31 is installed on the fuel input pipe 33 and is located inside the heater 1 to ensure that the ammonia cracker 31 reaches the required temperature for ammonia cracking. The ammonia cracker 31 is filled with a catalyst that can catalytically crack high-temperature ammonia at approximately 750°C into hydrogen and nitrogen. The hydrogen, nitrogen, and uncracked ammonia produced after cracking are mixed and fed into the fuel stack 2.

[0039] Specifically, the SOFC power generation system also includes an energy conversion device 6, which is electrically connected to the fuel cell stack 2. The energy conversion device 6 is existing technology and includes an AC / DC converter and a battery for converting and storing the electrical energy generated by the fuel cell stack 2.

[0040] The beneficial effects of this embodiment are as follows: By setting up the spiral tube assembly 51, which is spirally coiled around the fuel cell stack 2, heat exchange can be carried out between the spiral tube assembly 51 and the fuel cell stack 2 to regulate the temperature of the fuel cell stack 2. Simultaneously, the air input to the fuel cell stack 2 is heated within the spiral tube assembly 51 to achieve a suitable input temperature. The entire spiral tube assembly 51, coiled around the fuel cell stack 2, not only regulates the temperature of the fuel cell stack 2 and utilizes the heat energy generated by the fuel cell stack 2, but also eliminates the need for a separate installation space for the spiral tube assembly 51, simplifying the overall structure and reducing design complexity.

[0041] The above description is only a preferred embodiment of the present invention. For those skilled in the art, there will be changes in the specific implementation and application scope based on the ideas of the present invention. The content of this specification should not be construed as a limitation of the present invention.

Claims

1. An SOFC power generation system, characterized in that, include: Heating furnace; An electric fuel cell stack, installed inside the heating furnace, the electric fuel cell stack being used to generate electrical energy; A fuel supply device is connected to the fuel inlet of the fuel cell stack and is used to supply ammonia fuel to the fuel cell stack. A combustion device is provided, with its two ends connected to the fuel outlets of the heating furnace and the electric stack, respectively. The combustible exhaust gas discharged from the fuel outlet is burned in the combustion device to generate high-temperature flue gas, which is used to heat the heating furnace. An air supply device is provided for supplying air to the fuel cell stack. The air supply device includes a spiral tube assembly that is spirally wound around the fuel cell stack. One end of the spiral tube assembly is connected to an air source, and the other end is connected to the air inlet of the fuel cell stack.

2. The SOFC power generation system according to claim 1, characterized in that, The spiral tube assembly includes a first tube section, a second tube section, and a third tube section connected in sequence. The first tube section is connected to the air source and is located at the end of the fuel cell stack near the fuel outlet. The third tube section is connected to the air inlet and is located at the end of the fuel cell stack near the fuel inlet. The flow velocity of the first tube section is S1, the flow velocity of the second tube section is S2, and the flow velocity of the third tube section is S3, where S1 < S2 and S3 < S2.

3. The SOFC power generation system according to claim 2, characterized in that, The inner diameter of the first pipe segment is greater than the inner diameter of the second pipe segment, and the inner diameter of the third pipe segment is greater than the inner diameter of the second pipe segment.

4. The SOFC power generation system according to claim 3, characterized in that, The inner diameter of the first pipe section is 12mm, the inner diameter of the second pipe section is 8mm, and the inner diameter of the third pipe section is 10mm.

5. The SOFC power generation system according to claim 2, characterized in that, The pitch of the first pipe segment is smaller than the pitch of the second pipe segment and the third pipe segment.

6. The SOFC power generation system according to claim 2, characterized in that, Along the axial direction of the first pipe section, multiple baffles are provided at intervals within the first pipe section.

7. The SOFC power generation system according to claim 6, characterized in that, Multiple baffles are alternately distributed on the inner walls of opposite sides of the first pipe section.

8. The SOFC power generation system according to any one of claims 1 to 7, characterized in that, The air supply device further includes a preheater, which is disposed between the air source and the spiral tube assembly. The preheater is connected to the air outlet of the fuel cell stack so that the preheater exchanges heat with the high-temperature air discharged from the air outlet.

9. The SOFC power generation system according to any one of claims 1 to 7, characterized in that, The fuel supply device includes an ammonia pyrolyzer installed inside the heating furnace, with its outlet connected to the fuel inlet of the fuel cell stack.

10. The SOFC power generation system according to any one of claims 1 to 7, characterized in that, It also includes an energy conversion device, which is electrically connected to the fuel cell stack and is used to convert and store electrical energy.

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