A natural gas SOFC cogeneration system

Abstract

The utility model provides a natural gas SOFC cogeneration system, include: fuel supply module for supplying fuel, air supply module for supplying air, combustion reforming module for carrying out the combustion and reforming reaction of fuel, recovery module for recycling waste heat and water resources, electric pile module for carrying out electrochemical power generation reaction, electric energy conversion module for processing the electric energy that electric pile module produces, the utility model constructs a highly integrated modular system, and multiple modules of fuel supply, combustion reforming, power generation, waste heat recovery and water recovery organically couple, realize the step -by -step utilization of energy and the recycling of resources.

Description

Technical Field

[0001] This utility model relates to the field of solid oxide fuel cell technology, and in particular to a natural gas SOFC cogeneration system. Background Technology

[0002] Solid oxide fuel cells (SOFCs) are widely used in distributed power generation due to their high energy conversion efficiency and low emissions. Natural gas SOFC systems, which convert natural gas into hydrogen for power generation through high-temperature reforming, represent an important direction for new energy utilization. The natural gas reforming hydrogen production reaction is a typical endothermic reaction, requiring a continuous and stable heat source, which is crucial to the efficiency and stability of the SOFC system. Currently, the mainstream heat source supply methods in the industry face several technical bottlenecks: First, using electric heating to heat the reforming reaction requires additional consumption of the system's generated electricity, significantly reducing the overall operating efficiency of the SOFC power generation system and highlighting energy waste. Second, when directly feeding natural gas for combustion heating, some natural gas is consumed without participating in the electrochemical reaction, reducing power generation efficiency and increasing fuel costs. Third, using tail gas catalytic combustion heating results in a complex system structure, high maintenance difficulty, and slow heating rate, making it unsuitable for applications requiring rapid start-up.

[0003] To address the shortcomings of traditional heat source supply, existing technologies have proposed targeted improvement schemes. For example, Chinese invention patent document CN117293362A discloses a natural gas reforming power generation system. Through the coordinated design of a fuel supply device, an air supply device, a natural gas combustion reforming device, a fuel cell stack, and an energy conversion device, it utilizes the high-temperature flue gas generated by the burner to power the reformer. Simultaneously, heat exchange between the combustion exhaust gas and the fuel and air supply devices is achieved through an exhaust gas transmission channel, thus avoiding to some extent the efficiency losses associated with traditional electric heating or direct fuel combustion. Furthermore, adaptive control of the combustion temperature is achieved through a temperature regulation device. However, this technology still has the following deficiencies: Water resources rely on external replenishment and lack self-sufficiency: the fuel supply unit is only equipped with ordinary water tanks, and the water required for natural gas reforming depends entirely on continuous external water replenishment. In scenarios where there is a lack of stable water sources, such as in the wild or remote areas, the system cannot achieve long-term independent operation, and its application scenarios are limited. At the same time, external water replenishment not only increases the operating cost of the system, but may also affect the reforming reaction efficiency and stack life due to water quality fluctuations.

[0004] The depth of waste heat recovery is insufficient, and there is still room for improvement in energy utilization: After the combustion exhaust gas undergoes two-stage heat exchange, it is discharged through a Y-shaped pipe. The exhaust gas still contains medium and low temperature waste heat. This unused waste heat not only causes energy waste, but also increases the risk of environmental thermal pollution due to the high temperature of the exhaust gas. Utility Model Content

[0005] In view of the shortcomings of existing technologies, this utility model aims to solve the technical problem of how to improve the water resource self-sufficiency and waste heat recovery and utilization rate of natural gas SOFC systems, thereby expanding application scenarios and reducing operating costs.

[0006] To solve the above-mentioned technical problems, this utility model provides a natural gas SOFC cogeneration system, comprising: The fuel supply module is used to supply fuel. An air supply module is used to supply air. The combustion and reforming module is used for the combustion and reforming reaction of fuel; The recycling module is used to recover waste heat and water resources; Fuel cell stack module, used for electrochemical power generation reactions; A power conversion module is used to process the electrical energy generated by the fuel cell stack module; The fuel supply module's output is connected to the fuel input of the combustion reforming module; the reformed gas output of the combustion reforming module is connected to the anode input of the fuel cell stack module; the air output of the air supply module is connected to the cathode input of the fuel cell stack module; the exhaust gas output of the fuel cell stack module is connected to the exhaust gas input of the combustion reforming module; the heat exchange exhaust gas output of the combustion reforming module is connected to the heat exchange exhaust gas inputs of both the fuel supply module and the air supply module; the heat exchange exhaust gas outputs of both the fuel supply module and the air supply module are connected to the heat exchange exhaust gas input of the recovery module; the condensate output of the recovery module is connected to the water supply of the fuel supply module; and the power conversion module is electrically connected to the fuel cell stack module.

[0007] This invention constructs a highly integrated modular system that organically couples multiple modules, including fuel supply, combustion reforming, power generation, waste heat recovery, and water recovery, achieving cascaded energy utilization and resource recycling. Specifically, this technical solution significantly reduces dependence on external energy sources and improves overall system efficiency by diverting the fuel cell stack exhaust gas back to the combustion reforming module as partial fuel and utilizing its combustion heat to heat the reforming reaction. Simultaneously, the recovery module performs deep heat exchange and water recovery on the final exhaust gas, not only recovering medium- and low-temperature waste heat but also achieving self-sufficiency in reforming water and avoiding harmful gas emissions.

[0008] Furthermore, the recovery module includes a waste heat recovery heat exchanger, a circulating water pump, an insulated water tank, and a condensate pipe. The heat exchange exhaust gas inlet of the waste heat recovery heat exchanger is connected to the heat exchange exhaust gas output end of the fuel supply module and the air supply module. Its water-side inlet is connected to the outlet of the circulating water pump, and its water-side outlet is connected to the inlet of the insulated water tank. The inlet of the circulating water pump is connected to the outlet of the insulated water tank. The inlet end of the condensate pipe is connected to the condensate outlet of the waste heat recovery heat exchanger, and its outlet end is connected to the water supply end of the fuel supply module. The recovery module enables deep recovery of waste heat at the end of the system and closed-loop management of water resources. The waste heat recovery heat exchanger uses the waste heat from the exhaust gas, which has been significantly reduced in temperature after multiple uses, to heat water, greatly improving the overall thermoelectric efficiency and economy of the system. At the same time, during the process of cooling the exhaust gas to room temperature, a large amount of water vapor contained in it is condensed and recovered, and then sent back to the fuel supply module through the condensate pipeline for direct use in the reforming hydrogen production reaction. This allows the system to operate stably for a long time even in the absence of external water sources, achieving resource recycling.

[0009] Furthermore, the insulated water tank is connected to a tap water inlet pipe and a warm water outlet pipe. The warm water outlet pipe is equipped with a mixing valve, and the tap water inlet pipe is connected to the mixing valve. The high-temperature hot water flowing out of the insulated water tank can be mixed with cold water as needed to directly output suitable warm water, meeting the actual needs of daily water use.

[0010] Furthermore, the fuel supply module includes a reforming water tank, a water supply pump, a natural gas pipeline, and a vaporization superheater. The outlet of the condensate pipeline is connected to the water inlet of the reforming water tank, the inlet of the water supply pump is connected to the outlet of the reforming water tank, the outlet of the water supply pump is connected to the water inlet of the vaporization superheater, the natural gas pipeline is connected to the natural gas inlet of the vaporization superheater, the mixed gas outlet of the vaporization superheater is connected to the fuel input of the combustion reforming module, the heat exchange exhaust gas inlet of the vaporization superheater is connected to the heat exchange exhaust gas output of the combustion reforming module, and its heat exchange exhaust gas outlet is connected to the heat exchange exhaust gas inlet of the waste heat recovery heat exchanger. The fuel supply module utilizes the high-temperature exhaust gas in the system as a heat source to simultaneously vaporize and superheat water and natural gas, preparing suitable and uniformly mixed feedstock gas for the subsequent reforming reaction. This not only ensures the efficiency of the reforming reaction but also enables efficient utilization of internal system energy and reduces external energy input.

[0011] Furthermore, the air supply module includes an air supply fan and an air preheater. The air inlet of the air preheater is connected to the outlet of the air supply fan, its air outlet is connected to the cathode input terminal of the fuel cell stack module, its heat exchange exhaust gas inlet is connected to the heat exchange exhaust gas output terminal of the combustion reforming module, and its heat exchange exhaust gas outlet is connected to the heat exchange exhaust gas inlet of the waste heat recovery heat exchanger. By setting up the air preheater, the high-temperature exhaust gas is used to preheat the air entering the fuel cell stack cathode, which helps to improve the electrochemical reaction efficiency inside the fuel cell stack, thereby improving the power generation performance of the system.

[0012] Furthermore, the combustion reforming module includes a fuel pipeline, a burner, and a reformer. The fuel pipeline is connected to the fuel inlet of the burner, the fuel cell stack exhaust gas inlet of the burner is connected to the exhaust gas output terminal of the fuel cell stack module, the combustion exhaust gas outlet of the burner is connected to the heat exchange exhaust gas inlet of the reformer, the feed inlet of the reformer is connected to the mixed gas outlet of the vaporization superheater, its reformed gas outlet is connected to the anode input terminal of the fuel cell stack module, and its heat exchange exhaust gas outlet is connected to the heat exchange exhaust gas inlets of the vaporization superheater and the air preheater, respectively. The burner simultaneously receives external fuel and fuel cell stack exhaust gas and mixes and combusts them, providing a stable high-calorific-value heat source for the reformer. The combustion reforming module treats both the anode exhaust gas containing unreacted fuel and the cathode exhaust gas containing residual oxygen together, safely eliminating combustible components in the exhaust gas and preventing environmental pollution, while converting the chemical energy contained within into thermal energy for the reforming reaction, realizing internal energy circulation and significantly improving fuel utilization.

[0013] Furthermore, the combustion reforming module also includes an oxygen sensor, which is installed on the combustion exhaust gas outlet connection pipe of the burner. The oxygen sensor can monitor the oxygen content of the combustion exhaust gas in real time, providing a direct basis for determining whether the fuel (including natural gas and combustible gases in the exhaust gas) is completely burned.

[0014] Furthermore, the oxygen sensor is connected to the control terminal of the air supply fan to adjust the speed of the air supply fan based on the detected oxygen content. Linking the monitoring signal of the oxygen sensor with the control terminal of the air supply fan forms a closed-loop feedback control system. This system can automatically adjust the supply of combustion air according to real-time combustion conditions, ensuring the optimal air-fuel ratio is maintained under any operating condition. This achieves complete fuel combustion, optimizes combustion efficiency, and ensures clean emissions.

[0015] Furthermore, the power conversion module includes a power converter and a battery. The input terminal of the power converter is electrically connected to the power output terminal of the fuel cell stack module, and the output terminal of the power converter is electrically connected to the battery. The power converter converts the DC power generated by the fuel cell stack module into the type of power required by the user, and can store excess power in the battery, ensuring the stability, availability, and flexibility of the system's output power and meeting diverse power needs.

[0016] Furthermore, the power converter includes a DC / DC converter and a DC / AC converter. The DC / DC converter is used to regulate or boost the DC power generated by the fuel cell module, while the DC / AC converter converts it into AC power, so that the power generated by the system can be easily connected to the power grid or directly supply power to AC loads.

[0017] In summary, compared with the prior art, this utility model has the following beneficial effects: (1) This utility model realizes the cascade utilization of energy and the closed-loop circulation of resources by constructing a modular integrated system of fuel supply, air supply, combustion reforming, waste heat and water recovery, electric stack power generation and power conversion. It innovatively designs a recovery module including a waste heat recovery heat exchanger and condensate pipe, which can use the waste heat in the low temperature tail gas at the end of the system to heat domestic water and efficiently condense and recover water vapor in the tail gas for reforming hydrogen production reaction. This design frees the system from dependence on a stable external water source and solves the technical bottleneck of not being able to operate stably for a long time in scenarios such as the field and remote areas where water replenishment is lacking. It greatly expands the application scope of the system.

[0018] (2) This utility model achieves deep recovery of waste heat from combustion flue gas by optimizing the thermal management process. The high-temperature flue gas provides heat to the reformer, vaporization superheater and air preheater in sequence. Finally, the recovery module condenses the exhaust gas close to the ambient temperature and recovers water, thus maximizing the exploitation of energy potential and solving the problems of insufficient waste heat recovery depth and high exhaust gas temperature in the existing technology, which cause energy waste and environmental thermal pollution.

[0019] (3) The cogeneration system of this utility model draws the tail gas of the electric stack back to the burner as fuel and uses the high-temperature flue gas generated by its combustion to heat the reforming reaction, which significantly reduces the consumption of additional energy and fundamentally solves the problem of low system efficiency caused by electric heating or direct fuel combustion in traditional technologies, and greatly improves the comprehensive energy utilization rate of cogeneration. Attached Figure Description

[0020] Figure 1 This is a diagram showing the module connection relationship of the natural gas SOFC cogeneration system in an embodiment of this utility model.

[0021] Figure 2 This is a process flow diagram of the natural gas SOFC cogeneration system in this embodiment of the utility model.

[0022] Explanation of reference numerals in the attached figures: 1-Fuel supply module, 11-Reform water tank, 12-Water supply pump, 13-Natural gas pipeline, 14-Vaporization superheater, 2-Air supply module, 21-Gas supply fan, 22-Air preheater, 3-Combustion reforming module, 31-Fuel pipeline, 32-Burner, 33-Oxygen sensor, 34-Reformer, 4-Recovery module, 41-Waste heat recovery heat exchanger, 42-Circulating water pump, 43-Insulated water tank, 44-Condensate pipeline, 45-Tap water inlet pipe, 46-Warm water outlet pipe, 47-Mixing valve, 5-Fuel stack module, 6-Energy conversion module, 61-Power converter, 62-Battery. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] It should be noted that similar symbols and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0025] Combination Figure 1 As shown in the figure, a specific embodiment of this utility model provides a natural gas SOFC cogeneration system, including a fuel supply module 1, an air supply module 2, a combustion reforming module 3, a recovery module 4, an electric stack module 5, and an energy conversion module 6. Through modular integration, this system realizes the cascade utilization of energy and the closed-loop circulation of resources.

[0026] The functions of each module are as follows: Fuel supply module 1 is used to supply fuel, specifically a mixture of natural gas and steam; Air supply module 2 is used to supply air; Combustion reforming module 3 is used to carry out the combustion and reforming reaction of fuel, specifically reforming the natural gas-steam mixture into hydrogen-rich reformed gas; Recovery module 4 is used to recover waste heat and water resources from the system; Stack module 5 is used to receive reformed gas and air and carry out electrochemical power generation reaction; Power conversion module 6 is used to process the electrical energy generated by stack module 5, enabling direct use or storage of electrical energy.

[0027] The connection methods for each module are as follows: Figure 1The solid line represents the raw material pipeline, the dashed line represents the exhaust gas pipeline, the dotted line represents the electrical connection, and the arrow indicates the flow direction: The output end of the fuel supply module 1 is connected to the fuel input end of the combustion reforming module 3, delivering the natural gas-steam mixture to the combustion reforming module 3; the reformed gas output end of the combustion reforming module 3 is connected to the anode input end of the fuel cell stack module 5, delivering the reformed gas to the fuel cell stack anode; the air output end of the air supply module 2 is connected to the cathode input end of the fuel cell stack module 5, delivering air to the fuel cell stack cathode; the power conversion module 6 is electrically connected to the fuel cell stack module 5. The heat exchange exhaust gas output of the combustion reforming module 3 is connected to the heat exchange exhaust gas input of the fuel supply module 1 and the air supply module 2, respectively. The heat exchange exhaust gas output of the fuel supply module 1 and the air supply module 2 is connected to the heat exchange exhaust gas input of the recovery module 4, so that the waste heat of the exhaust gas is fully utilized. The condensate output of the recovery module 4 is connected to the water supply end of the fuel supply module 1, so that the water vapor in the exhaust gas is recovered and reused. Through the deep heat exchange and water recovery of the exhaust gas by the recovery module 4, the self-sufficiency of reforming water is achieved, and the emission of harmful gases is avoided.

[0028] Combination Figure 2 As shown in the figure, solid lines represent raw material pipelines, dashed lines represent exhaust gas pipelines, and dotted lines represent electrical connections. The specific module structure of the natural gas SOFC cogeneration system in the embodiment is as follows: Fuel supply module 1 includes a reforming water tank 11, a water supply pump 12, a natural gas pipeline 13, and a vaporization superheater 14. The reforming water tank 11 stores reforming water and is connected to the water inlet of the vaporization superheater 14 via the water supply pump 12. The natural gas pipeline 13 is connected to the natural gas inlet of the vaporization superheater 14. The mixed gas outlet of the vaporization superheater 14 is connected to the fuel input of the combustion reforming module 3.

[0029] The air supply module 2 includes an air supply fan 21 and an air preheater 22. The air preheater 22 is used to preheat the air. The outlet of the air supply fan 21 is connected to the air inlet of the air preheater 22, and the air outlet of the air preheater 22 is connected to the cathode input terminal of the fuel cell stack module 5.

[0030] The combustion reforming module 3 includes a fuel pipeline 31, a burner 32, an oxygen sensor 33, and a reformer 34. The fuel pipeline 31 is connected to the fuel inlet of the burner 32 for introducing start-up fuel or supplemental fuel. The burner 32 has a fuel cell stack exhaust gas inlet, connected to the anode exhaust gas outlet and cathode exhaust gas outlet of the fuel cell stack module 5. The burner 32 simultaneously receives external fuel and fuel cell stack exhaust gas and mixes them for combustion, providing a stable high-calorific-value heat source for the reformer. The oxygen sensor 33 is installed on the combustion exhaust gas outlet connecting pipeline of the burner 32 for real-time monitoring of the oxygen content in the flue gas after combustion. Preferably, the oxygen sensor 33 is connected to the control terminal of the air supply fan 21 to form a closed-loop feedback control system, which adjusts the speed of the air supply fan 21 according to the detected oxygen content, and can automatically adjust the supply of combustion air according to the real-time combustion conditions. The feed inlet of the reformer 34 is connected to the mixed gas outlet of the vaporization superheater 14. The reformer 34 reforms the natural gas-steam mixture into hydrogen-rich reformed gas, and its reformed gas outlet is connected to the anode input terminal of the fuel cell stack module 5. The heat exchange exhaust gas inlet of the reformer 34 is connected to the combustion exhaust gas outlet of the burner 32, absorbing the heat from the high-temperature flue gas generated by the burner 32. After heat exchange, the waste heat exhaust gas is divided into two paths. The heat exchange exhaust gas outlet of the reformer 34 is connected to the heat exchange exhaust gas inlet of the vaporization superheater 14 of the fuel supply module 1 and the heat exchange exhaust gas inlet of the air preheater 22 of the air supply module 2, respectively, for waste heat recovery and utilization.

[0031] The recovery module 4 includes a waste heat recovery heat exchanger 41, a circulating water pump 42, an insulated water tank 43, and a condensate pipe 44. The waste heat recovery heat exchanger 41 reuses the exhaust gas that has undergone heat exchange with the fuel supply module 1 and the air supply module 2 to heat the water in the insulated water tank 43. Its exhaust gas inlet is connected to the exhaust gas outlets of the vaporization superheater 14 and the air preheater 22, respectively. The exhaust gas outlet can be connected to the atmospheric environment to discharge the ambient temperature exhaust gas from the system. The water-side inlet of the waste heat recovery heat exchanger 41 is connected to the outlet of the insulated water tank 43 via the circulating water pump 42, and its water-side outlet is connected to the inlet of the insulated water tank 43, realizing the circulating heating of the water in the insulated water tank 43. The waste heat recovery heat exchanger 41 also has a condensate outlet, which is connected to the reforming water tank 11 of the fuel supply module 1 via the condensate pipe 44, condensing and recovering the water vapor in the exhaust gas for direct use in the reforming hydrogen production reaction, realizing resource recycling within the system. The insulated water tank 43 is connected to a tap water inlet pipe 45 and a warm water outlet pipe 46. The tap water inlet pipe 45 is used to replenish the insulated water tank 43 with cold water, and the warm water outlet pipe 46 outputs hot water, which can be used for domestic water or heating. Preferably, the warm water outlet pipe 46 is equipped with a mixing valve 47, and the tap water inlet pipe 45 is connected to the mixing valve 47. The mixing valve 47 is used to adjust the mixing ratio of hot and cold water to output water at a suitable temperature.

[0032] The fuel cell stack module 5 includes a solid oxide fuel cell stack. Its anode inlet receives hydrogen-rich reformed gas from the reformer 34 of the combustion reforming module 3, and its cathode inlet receives preheated air from the air preheater 22 of the air supply module 2. Direct current is generated through electrochemical reaction. The anode tail gas and cathode tail gas generated by the fuel cell stack module 5 enter the burner 32 for combustion treatment.

[0033] The power conversion module 6 includes a power converter 61 and a battery 62. The input terminal of the power converter 61 is electrically connected to the DC output terminal of the fuel cell module 5, and is used to regulate (DC / DC) and convert (DC / AC) the generated DC power. Its output terminal can be connected to the battery 62 for energy storage, or directly output usable DC or AC power.

[0034] The workflow of each module in a natural gas SOFC cogeneration system is as follows: When the system starts up, external natural gas enters the burner 32 through the fuel pipeline 31 and is burned. The high-temperature flue gas produced provides the initial heat source for the reformer 34.

[0035] After the system stabilizes, the anode and cathode exhaust gases from fuel cell module 5 are introduced into burner 32 and mixed with natural gas supplied via fuel pipeline 31 for combustion. The high-temperature flue gas from burner 32 enters reformer 34, providing the necessary heat for the reforming reaction. Meanwhile, the natural gas-water vapor mixture from fuel supply module 1, which has been fully mixed and preheated in vaporization superheater 14, enters reformer 34 and undergoes a reforming reaction to generate hydrogen-rich reformed gas. This reformed gas then enters the anode of fuel cell module 5 to participate in the electrochemical reaction for power generation. Oxygen sensor 33 monitors the oxygen concentration in the post-combustion flue gas in real time and transmits the signal to the control terminal of the air supply fan 21, forming a closed-loop control system. By dynamically adjusting the combustion air volume, complete combustion of the fuel is ensured under any operating conditions.

[0036] The high-temperature exhaust gas after heat exchange in reformer 34 is divided into two streams. One stream enters vaporization superheater 14, where the liquid water supplied by water pump 12 is vaporized into steam and mixed with natural gas for superheating. The other stream enters air preheater 22, where the ambient temperature air supplied by air supply fan 21 is preheated. The preheated air then enters the cathode of fuel cell module 5.

[0037] The exhaust gases from the vaporization superheater 14 and air preheater 22 merge and enter the waste heat recovery heat exchanger 41 of the recovery module 4. Here, the exhaust gases undergo final heat exchange with water pumped from the bottom of the insulated water tank 43 by the circulating water pump 42. After being cooled to near room temperature, the exhaust gases are discharged into the atmosphere, with most of the water vapor condensed. The condensate is collected through the condensate pipe 44 and returned to the reforming water tank 11, achieving self-sufficiency in reforming water. The heated hot water is returned to the insulated water tank 43 for storage. The hot water from the insulated water tank 43 is mixed with cold water through the warm water outlet pipe 46 and mixing valve 47 to output warm water at a suitable temperature for domestic use.

[0038] The natural gas SOFC cogeneration system provided in the above embodiments has successfully achieved the technical objectives of improving system efficiency, water self-sufficiency, and deep waste heat recovery through modular design and precise process control. It is particularly suitable for application scenarios such as distributed energy and power supply in remote areas.

[0039] Although the present invention has been disclosed above, its protection scope is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. A natural gas SOFC cogeneration system, characterized in that, include: Fuel supply module (1), used to supply fuel; Air supply module (2), used to supply air; Combustion reforming module (3) is used for the combustion and reforming reaction of fuel; The recycling module (4) is used to recover waste heat and water resources; The fuel cell stack module (5) is used for electrochemical power generation reactions; The power conversion module (6) is used to process the electrical energy generated by the fuel cell module (5); The output end of the fuel supply module (1) is connected to the fuel input end of the combustion reforming module (3), the reforming gas output end of the combustion reforming module (3) is connected to the anode input end of the fuel cell stack module (5), the air output end of the air supply module (2) is connected to the cathode input end of the fuel cell stack module (5), the exhaust gas output end of the fuel cell stack module (5) is connected to the exhaust gas input end of the combustion reforming module (3), the heat exchange exhaust gas output end of the combustion reforming module (3) is connected to the heat exchange exhaust gas input ends of the fuel supply module (1) and the air supply module (2) respectively, the heat exchange exhaust gas output ends of the fuel supply module (1) and the air supply module (2) are connected to the heat exchange exhaust gas input end of the recovery module (4), the condensate output end of the recovery module (4) is connected to the water supply end of the fuel supply module (1), and the power conversion module (6) is electrically connected to the fuel cell stack module (5).

2. The natural gas SOFC cogeneration system according to claim 1, characterized in that, The recovery module (4) includes a waste heat recovery heat exchanger (41), a circulating water pump (42), an insulated water tank (43), and a condensate pipe (44). The heat exchange exhaust gas inlet of the waste heat recovery heat exchanger (41) is connected to the heat exchange exhaust gas output end of the fuel supply module (1) and the air supply module (2). Its water side inlet is connected to the outlet of the circulating water pump (42), and its water side outlet is connected to the inlet of the insulated water tank (43). The inlet of the circulating water pump (42) is connected to the outlet of the insulated water tank (43). The inlet end of the condensate pipe (44) is connected to the condensate outlet of the waste heat recovery heat exchanger (41), and its outlet end is connected to the water supply end of the fuel supply module (1).

3. The natural gas SOFC cogeneration system according to claim 2, characterized in that, The insulated water tank (43) is connected to a tap water inlet pipe (45) and a warm water outlet pipe (46). The warm water outlet pipe (46) is equipped with a mixing valve (47), and the tap water inlet pipe (45) is connected to the mixing valve (47).

4. The natural gas SOFC cogeneration system according to claim 2, characterized in that, The fuel supply module (1) includes a reforming water tank (11), a water supply pump (12), a natural gas pipeline (13), and a vaporization superheater (14). The outlet end of the condensate pipeline (44) is connected to the water inlet of the reforming water tank (11). The inlet of the water supply pump (12) is connected to the outlet of the reforming water tank (11). The outlet of the water supply pump (12) is connected to the water inlet of the vaporization superheater (14). The natural gas pipeline (13) is connected to the natural gas inlet of the vaporization superheater (14). The mixed gas outlet of the vaporization superheater (14) is connected to the fuel input end of the combustion reforming module (3). The heat exchange tail gas inlet of the vaporization superheater (14) is connected to the heat exchange tail gas output end of the combustion reforming module (3). Its heat exchange tail gas outlet is connected to the heat exchange tail gas inlet of the waste heat recovery heat exchanger (41).

5. The natural gas SOFC cogeneration system according to claim 4, characterized in that, The air supply module (2) includes an air supply fan (21) and an air preheater (22). The air inlet of the air preheater (22) is connected to the outlet of the air supply fan (21), and its air outlet is connected to the cathode input of the fuel cell module (5). Its heat exchange exhaust gas inlet is connected to the heat exchange exhaust gas output of the combustion reforming module (3), and its heat exchange exhaust gas outlet is connected to the heat exchange exhaust gas inlet of the waste heat recovery heat exchanger (41).

6. The natural gas SOFC cogeneration system according to claim 5, characterized in that, The combustion reforming module (3) includes a fuel pipeline (31), a burner (32), and a reformer (34). The fuel pipeline (31) is connected to the fuel inlet of the burner (32). The fuel cell tail gas inlet of the burner (32) is connected to the tail gas output end of the fuel cell module (5). The combustion tail gas outlet of the burner (32) is connected to the heat exchange tail gas inlet of the reformer (34). The raw material inlet of the reformer (34) is connected to the mixed gas outlet of the vaporization superheater (14). Its reformed gas outlet is connected to the anode input end of the fuel cell module (5). Its heat exchange tail gas outlet is connected to the heat exchange tail gas inlet of the vaporization superheater (14) and the heat exchange tail gas inlet of the air preheater (22), respectively.

7. The natural gas SOFC cogeneration system according to claim 6, characterized in that, The combustion reforming module (3) also includes an oxygen sensor (33), which is installed on the combustion exhaust gas outlet connecting pipe of the burner (32).

8. The natural gas SOFC cogeneration system according to claim 7, characterized in that, The oxygen sensor (33) is connected to the control terminal of the air supply fan (21) and is used to adjust the speed of the air supply fan (21) according to the detected oxygen content.

9. The natural gas SOFC cogeneration system according to claim 1, characterized in that, The power conversion module (6) includes a power converter (61) and a battery (62). The input terminal of the power converter (61) is electrically connected to the power output terminal of the fuel cell module (5), and the output terminal of the power converter (61) is electrically connected to the battery (62).

10. The natural gas SOFC cogeneration system according to claim 9, characterized in that, The power converter (61) includes a DC / DC converter and a DC / AC converter.

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