Anode tail gas recirculation SOFC power generation system and operation method thereof

Abstract

The invention relates to an anode tail gas recirculation SOFC power generation system and an operation method thereof. The system comprises an SOFC electric pile module, a catalytic combustor, a starting combustor, a desulfurizer, a fuel preheater, a reformer, a fuel reheater, a circulating fan, a steam generator, a condenser, a fan, an air preheater, an electric control valve, a first stop valve, a second stop valve and a third stop valve. Wherein fuel and air in the catalytic combustor are mutually isolated and exchange heat, liquid water and CO2 are obtained after smoke generated by combustion of the fuel and the air is condensed, and the fuel is fuel which is not completely reacted at an outlet of the SOFC electric pile module. According to the embodiment of the invention, on the basis of an anode tail gas recirculation process, fuel which is not completely reacted at the outlet of the SOFC electric pile module is catalytically combusted by utilizing the catalytic combustor, and the combusted flue gas is condensed to obtain liquid water and CO2, so that an SOFC system gets rid of dependence on external water supply under a rated operation condition, and meanwhile, high-purity CO2 is captured.

Description

Technical Field

[0001] The present application relates to the technical field of fuel cell systems, and in particular to an anode tail gas recirculation SOFC power generation system and an operation method thereof. Background Art

[0002] Solid Oxide Fuel Cell (SOFC) is the most efficient power generation technology among all power generation equipment. The power generation efficiency of a single unit can reach more than 60%. It can use natural gas, biogas, refinery gas, coke oven gas, etc. as fuel, and does not produce nitrogen oxides, sulfur oxides and other pollutant emissions. The installed capacity of a single system can range from kW to 100 kW, and multiple systems can be connected in parallel to reach MW level. It has broad application prospects in the field of distributed power supply for civilian and commercial users such as residences, hotels, hospitals, schools, office buildings, communities, data centers, and communication base stations.

[0003] Currently, mainstream high-power SOFC power generation systems use natural gas as fuel. To extend the life of the stack, the fuel utilization rate during power generation is generally controlled below 85%. The anode exhaust gas at the stack outlet still contains a certain concentration of combustible components, which are burned to maintain system thermal balance. However, higher stack fuel utilization rates reduce stack life and make fuel distribution among multiple stacks within the system more difficult. Lower fuel utilization rates also lead to reduced system efficiency. In conventional high-power SOFC power generation systems, the fuel at the SOFC stack module outlet does not fully react to generate electricity. Instead, it mixes with the hot air at the SOFC stack module outlet in the burner to produce high-temperature flue gas, which is used to maintain system thermal balance and avoid the emission of combustible gases such as CO and H2. However, in existing technologies, the flue gas generated by the residual fuel at the stack module outlet, after mixing with air and burning, has a high flow rate and low CO2 content, making CO2 capture costly. Furthermore, SOFC power generation systems require water vapor during operation to prevent carbon accumulation of CH4 in the reformer and SOFC stack under high-temperature conditions. The recovery, reheating and evaporation of condensed water in the CO2 capture process increases the complexity of the system and reduces the system efficiency. Summary of the Invention

[0004] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0005] The embodiments of the present application provide an anode tail gas recirculation SOFC power generation system and an operation method thereof, which can get rid of the dependence on external water supply under rated operating conditions and at the same time achieve the capture of high-purity CO2.

[0006] This application provides the following technical solutions:

[0007] In the first aspect, an embodiment of the present application provides an anode tail gas recirculation SOFC power generation system, comprising a SOFC stack module, a catalytic burner, an electric control valve, a start-up burner, a desulfurizer, a fuel preheater, a reformer, a fuel reheater, a circulating fan, a steam generator, a condenser, a fan, an air preheater, a first stop valve, a second stop valve, and a third stop valve; the fuel and air in the catalytic burner are isolated from each other and exchange heat, and the flue gas generated by the combustion of the fuel and the air is condensed to obtain liquid water and CO2, and the fuel is the fuel that has not completely reacted at the outlet of the SOFC stack module.

[0008] In combination with the first aspect, in one embodiment of the present application, a portion of the anode exhaust gas at the outlet of the SOFC stack module passes through the electronically controlled valve, the reformer and the fuel preheater in sequence, and is mixed with the desulfurized natural gas before entering the circulation fan and the fuel pipeline.

[0009] In combination with the first aspect, in one embodiment of the present application, the catalytic burner adopts a heat exchange design, the catalytic burner includes a heat exchanger and a catalyst, the heat exchanger includes a fuel channel and an air channel, the fuel channel is provided with a fuel inlet, an O2 inlet, a fuel outlet and the catalyst for catalytic combustion, the air channel is provided with an air inlet and an air outlet; a portion of the anode exhaust gas from the outlet of the SOFC stack module enters the fuel channel of the catalytic burner and burns with O2 under the action of the catalyst to release heat, and the air from the outlet of the SOFC stack module in the air channel is heated by the heat exchanger.

[0010] In combination with the first aspect, in one embodiment of the present application, when the system is operating at rated speed, the first stop valve is in an open state and the second stop valve is in a closed state. The flue gas at the outlet of the fuel channel of the catalytic burner passes through the first stop valve, the reformer and the condenser in sequence to react to obtain CO2. The air at the outlet of the air channel of the catalytic burner passes through the starting burner and exchanges heat with the air at the outlet of the fan in the air preheater. The flue gas includes water vapor and CO2.

[0011] In combination with the first aspect, in one embodiment of the present application, an ignition device is provided in the starting burner, and the ignition device is used to activate the starting burner. The starting burner burns the fuel and air introduced into the SOFC power generation system so that the temperature in the catalytic burner reaches the temperature required for catalytic combustion.

[0012] In combination with the first aspect, in one embodiment of the present application, the reformer adopts a heat exchange type, and the reformer is provided with a cold side channel and a hot side channel. The cold side channel is filled with a reforming catalyst, and the hot side channel is respectively connected to the fuel channel outlet of the catalytic burner and the inlet of the condenser; when the system is operated at rated speed, the flue gas at the fuel channel outlet of the catalytic burner provides a heat source for the fuel reforming reaction in the cold side channel.

[0013] In combination with the first aspect, in one embodiment of the present application, the steam generator adopts an electric heating type, and during the heating and cooling stages of the SOFC power generation system, the flow rate of water vapor is 2.5 times the fuel flow rate; during the power generation stage of the SOFC power generation system, the flow rate of water vapor has a water-to-carbon ratio of 2 to 3 at the inlet of the reformer; during the rated power generation stage of the SOFC power generation system, the steam generator is in a closed state.

[0014] In combination with the first aspect, in one embodiment of the present application, the first stop valve is arranged on the pipeline between the fuel channel outlet pipeline tee of the catalytic burner and the hot side inlet pipeline tee of the reformer, the second stop valve is arranged on the pipeline between the flue gas outlet pipeline tee of the startup burner and the hot side inlet pipeline tee of the reformer, and the third stop valve is arranged on the pipeline between the fuel channel outlet tee of the catalytic burner and the fuel inlet of the startup burner.

[0015] In a second aspect, an embodiment of the present application provides an operating method for an anode tail gas recirculation SOFC power generation system, which is applied to the aforementioned anode tail gas recirculation SOFC power generation system, and the method comprises the following contents: (1) closing the first shut-off valve of the system, opening the second shut-off valve, the third shut-off valve and the blower of the system, introducing natural gas into the system and opening the circulating blower of the system, and when air and the natural gas enter the starting burner of the system, starting the ignition device in the starting burner to activate the starting burner to burn the natural gas; (2) when the temperature of the reformer and the SOFC stack module of the system exceeds 300°C and the fuel pipeline of the system exceeds 150°C, starting the steam generator of the system and supplying water vapor into the system to prevent carbon deposition in the reformer and the SOFC stack module; (3) when the fuel channel outlet temperature of the catalytic burner of the system exceeds 550°C, opening the first shut-off valve, introducing O2 into the catalytic burner, and closing the second shut-off valve; (4) when the SOFC stack module reaches the power generation temperature, adjusting the (5) when the system is in rated operation, CO2 is separated from the condenser of the system; (6) the flow rate of the natural gas is adjusted according to the current rate and fuel utilization rate of the SOFC stack module, and the steam generator is turned on and the flow rate of the water vapor is adjusted. , the speed of the circulating fan, the opening of the electric control valve and the flow rate of the O2; (7) when the outlet temperature of the fuel channel of the catalytic burner drops to 550°C, open the second stop valve and stop the introduction of the O2 into the catalytic burner; when the temperatures of the reformer and the SOFC stack module both drop to 300°C, turn off the steam generator; when the temperatures of the reformer and the SOFC stack module both drop to 100°C, turn off the circulating fan, stop the introduction of the natural gas into the system, and turn off the fan.

[0016] Compared with the existing technology, the advantages of this application are: based on the anode tail gas recirculation process, the system uses a heat exchange catalytic burner to catalytically burn the unreacted fuel at the outlet of the SOFC stack module. The fuel and air in the catalytic burner are completely isolated but exchange heat with each other. The flue gas after combustion is condensed to obtain liquid water and high-purity CO2. Under rated operating conditions, the SOFC system is free from dependence on external water supply and achieves complete capture of high-purity CO2. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0018] Figure 1 This is a process flow chart of an anode tail gas recirculation SOFC power generation system provided in an embodiment of the present application;

[0019] Figure numerals: SOFC stack module 1; catalytic burner 2; electronically controlled valve 3; start-up burner 4; desulfurizer 5; fuel preheater 6; reformer 7; fuel reheater 8; circulating fan 9; steam generator 10; condenser 11; fan 12; air preheater 13; first stop valve 14; second stop valve 15; third stop valve 16. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without inventive effort are within the scope of protection of this application.

[0021] It should be noted that although a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in an order different from that in the flowchart. The terms "first" and "second" in the specification, claims, and the above-mentioned figures are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the content disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limitations of the implementation of this application. Therefore, they have no technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed in this application without affecting the efficacy and purpose of this application. At the same time, the terms such as "upper", "lower", "left", "right", "middle", and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of the implementation of this application. Changes or adjustments in their relative relationships should also be considered as the scope of the implementation of this application without substantially changing the technical content.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein are for the purpose of describing the embodiments of this application only and are not intended to limit this application.

[0023] In conventional high-power SOFC power generation systems, the fuel at the SOFC stack module outlet fails to fully react to generate electricity. The high-temperature flue gas generated by mixing with the high-temperature air at the SOFC stack module outlet in the burner is used to maintain system thermal balance while avoiding the emission of combustible gases such as CO and H2. However, in existing technologies, the flue gas flow rate after the residual fuel at the stack module outlet mixes with air and burns is large and the CO2 content is low, making CO2 capture very costly. Furthermore, water vapor is required during SOFC power generation system operation to prevent carbon deposition of CH4 in the reformer and SOFC stack under high-temperature conditions. The recovery, reheating, and evaporation of condensed water during the CO2 capture process increases system complexity and reduces system efficiency.

[0024] In view of this, the embodiments of the present application provide an anode tail gas recirculation SOFC power generation system and an operating method of the anode tail gas recirculation SOFC power generation system. The power generation system includes a SOFC stack module, a catalytic burner, an electronically controlled valve, a startup burner, a desulfurizer, a fuel preheater, a reformer, a fuel reheater, a circulating fan, a steam generator, a condenser, a fan, an air preheater, a first stop valve, a second stop valve, and a third stop valve. In particular, the unreacted fuel from the SOFC stack module outlet can be isolated from the air in the catalytic burner and heat exchanged. The fuel and air are then burned, and the resulting flue gas is condensed to obtain liquid water and CO2. Based on the anode tail gas recirculation process, the embodiment of the present application utilizes a catalytic burner to catalytically burn the unreacted fuel at the outlet of the SOFC stack module. The fuel and air in the catalytic burner are completely isolated but exchange heat with each other. The flue gas after combustion is condensed to obtain liquid water and high-purity CO2. The SOFC system is free from dependence on external water supply under rated operating conditions, and at the same time achieves complete capture of high-purity CO2.

[0025] The specific implementation of this application will be described below with reference to the accompanying drawings:

[0026] like Figure 1As shown, the present application provides an anode tail gas recirculation SOFC power generation system, which includes a SOFC stack module 1, a catalytic burner 2, an electrically controlled valve 3, a start-up burner 4, a desulfurizer 5, a fuel preheater 6, a reformer 7, a fuel reheater 8, a circulating fan 9, a steam generator 10, a condenser 11, a fan 12, an air preheater 13, a first stop valve 14, a second stop valve 15, and a third stop valve 16. The SOFC stack module 1 is a modular structure composed of multiple SOFC cells connected and packaged in a specific manner. This module is the core component of the solid oxide fuel cell system, used to directly convert the chemical energy of the fuel into electrical energy. Based on the anode tail gas recirculation process, this system uses a heat exchange catalytic burner 2 to catalytically burn the unreacted fuel at the outlet of the SOFC stack module 1. The fuel and air in the catalytic burner 2 are completely isolated but exchange heat with each other. The flue gas after combustion is condensed to obtain liquid water and high-purity CO2. Under rated operating conditions, this system gets rid of its dependence on external water supply and realizes the complete capture of high-purity CO2.

[0027] In one embodiment, during system operation, a portion of the anode tail gas from the outlet of the SOFC stack module 1 can pass through the electronically controlled valve 3, the reformer 7, and the fuel preheater 6 in sequence, then be mixed with fresh and desulfurized natural gas, enter the circulation fan 9, and finally enter the fuel pipeline, thereby achieving the recirculation of the anode tail gas from the outlet of the SOFC stack module 1. The flow rate of the anode tail gas entering the circulation pipeline is determined by the opening of the electronically controlled valve 3 and the speed of the circulation fan 9.

[0028] In one embodiment, the catalytic burner 2 can adopt a heat exchange design, which consists of a heat exchanger and a catalyst. The heat exchanger is divided into a fuel channel and an air channel. The fuel channel is provided with a fuel inlet, a fuel outlet, an O2 inlet and a catalyst for catalytic combustion; the air channel is provided with an air inlet and an air outlet. During the operation of the system, a portion of the high-temperature anode exhaust gas at the outlet of the SOFC stack module 1 can enter the fuel channel of the catalytic burner 2, and then burn with O2 under the action of the catalyst to release heat, and heat the high-temperature air from the outlet of the SOFC stack module 1 in the air channel through the heat exchanger. It is worth noting that the air and the fuel exchange heat but do not mix.

[0029] It is understood that a catalytic burner can completely burn fuel without an open flame, with no restrictions on fuel flow fluctuations or concentration, but its catalyst operating temperature generally does not exceed 900°C. To facilitate efficient CO2 recovery, the catalytic burner used in this embodiment has a heat exchange function. The fuel and an appropriate flow of O2 entering the fuel channel can be completely burned, producing only CO2 and water vapor. The air in the air channel is used to cool the catalyst temperature. This achieves full combustion of the fuel without overheating, while simultaneously producing high-temperature flue gas free of N2 and O2, which facilitates efficient CO2 capture.

[0030] In one embodiment, when the system is operating at rated speed, first shut-off valve 14 is open and second shut-off valve 15 is closed. Flue gas, consisting of water vapor and CO2, exits the fuel channel of catalytic burner 2 and passes through first shut-off valve 14, reformer 7, and condenser 11, ultimately producing high-purity CO2. High-temperature air exits the air channel of catalytic burner 2 and passes through startup burner 4, where it exchanges heat with ambient-temperature air at the outlet of fan 12 in air preheater 13 before ultimately being transported to the waste heat recovery device.

[0031] In one embodiment, the startup burner 4 has a built-in ignition device. When the SOFC power generation system is in a cold start state, the incoming fuel and air can be collected in the startup burner 4 for combustion. The high-temperature flue gas generated by the combustion can be used to heat the system until the catalytic burner 2 reaches the required temperature for catalytic combustion.

[0032] In one embodiment, the reformer 7 can employ a heat exchange design, comprising a cold-side channel and a hot-side channel. The cold-side channel is filled with reforming catalyst, while the hot-side channel is connected to the fuel channel outlet of the catalytic burner 2 and the inlet of the condenser 11, respectively. When the system is operating at rated conditions, the high-temperature flue gas at the fuel channel outlet of the catalytic burner 2 can be used as a heat source for the fuel reforming reaction in the cold-side channel of the reformer 7, thereby ensuring that the composition of the reformer 7 outlet meets the requirements of the SOFC stack module 1.

[0033] In one embodiment, the steam generator 10 can be electrically heated and used during the SOFC system's heating, cooling, and low-current power generation phases to prevent carbon deposition in the reformer 7 and SOFC stack module 1. Specifically, during the SOFC system's heating and cooling phases, the steam flow rate is set at 2.5 times the fuel flow rate. During the SOFC system's power generation phase, the steam flow rate decreases as the SOFC stack module 1's power generation current increases, maintaining a water-to-carbon ratio between 2 and 3 at the reformer 7 inlet. During the SOFC system's rated power generation phase, the steam generator 10 is shut down.

[0034] In one embodiment, in the system, the first stop valve 14 is arranged on the pipeline between the tee of the fuel channel outlet pipeline of the catalytic burner 2 and the tee of the hot side inlet pipeline of the reformer 7, the second stop valve 15 is arranged on the pipeline between the tee of the flue gas outlet pipeline of the startup burner 4 and the tee of the hot side inlet pipeline of the reformer 7, and the third stop valve 16 is arranged on the pipeline between the tee of the fuel channel outlet of the catalytic burner 2 and the fuel inlet of the startup burner 4.

[0035] In addition, the present application also provides a method for operating an anode tail gas recirculation SOFC power generation system. This method is applicable to the aforementioned anode tail gas recirculation SOFC power generation system. That is, the method can be based on the coordinated operation of various components within the system. The specific contents may include:

[0036] (1) During the cold start phase of the SOFC power generation system, the first shut-off valve 14 is first closed, followed by the second and third shut-off valves 15 and 16. The blower 12 is then turned on to introduce natural gas into the system, while the circulating blower 9 is also turned on. After the air and natural gas enter the start-up burner 4, the ignition device is activated to activate the start-up burner 4, causing the natural gas to completely combust. The heat generated by the combustion is used to heat the SOFC power generation system.

[0037] (2) During the SOFC power generation system heating stage, when the temperatures of the reformer 7 and the SOFC stack module 1 exceed 300°C, and the fuel pipeline exceeds 150°C, the steam generator 10 is started to supply water vapor to the SOFC power generation system to prevent carbon deposition in the reformer 7 and the SOFC stack module 1.

[0038] (3) During the activation phase of the catalytic burner 2, when the temperature at the outlet of the fuel channel of the catalytic burner 2 exceeds 550°C, the first stop valve 14 is opened, and O2 is introduced into the catalytic burner 2 in an amount that is just sufficient for complete catalytic combustion of the fuel, and then the second stop valve 15 is closed.

[0039] (4) During the current loading phase, when the SOFC stack module 1 reaches the power generation temperature, the natural gas flow rate is increased, and the water vapor flow rate, the speed of the circulating fan 9, and the opening of the electronically controlled valve 3 are adjusted. At the same time, the fuel utilization rate of the SOFC stack module 1 is monitored, and the O2 flow rate is adjusted to ensure that the anode tail gas of the SOFC stack module 1 entering the catalytic combustor 2 is completely burned without residual O2, and to ensure that the current reaches the rated value stably and safely, and then the steam generator 10 is turned off.

[0040] (5) During the rated operation phase of the system, high-purity CO2 is separated from the condenser 11;

[0041] (6) During the current load reduction stage, according to the current reduction rate of the SOFC stack module 1 and the fuel utilization rate limit, the natural gas flow rate is reduced, the steam generator 10 is turned on and the water vapor flow rate is gradually increased, the speed of the circulating fan 9, the opening of the electric control valve 3 and the O2 flow rate are adjusted to ensure that the anode tail gas of the SOFC stack module 1 entering the catalytic burner 2 is completely burned without residual O2, and to ensure that the current is steadily reduced to 0.

[0042] (7) During the cooling phase of the system, the cooling operation can be performed at a cooling rate appropriate for the SOFC stack module 1. When the outlet temperature of the fuel channel of the catalytic burner 2 drops to 550°C, the second shut-off valve 15 is opened and the flow of O2 into the catalytic burner 2 is stopped; when the temperature of the reformer 7 and the SOFC stack module 1 drops to 300°C, the steam generator 10 is turned off; when the temperature of the reformer 7 and the SOFC stack module 1 drops to 100°C, the circulating fan 9 is turned off, the flow of natural gas into the system is stopped, and the fan 12 is turned off.

[0043] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An anode tail gas recirculation SOFC power generation system, comprising a SOFC stack module, a catalytic burner, an electric control valve, a start-up burner, a desulfurizer, a fuel preheater, a reformer, a fuel reheater, a circulating fan, a steam generator, a condenser, a fan, an air preheater, a first stop valve, a second stop valve, and a third stop valve; the fuel and air in the catalytic burner are isolated from each other and exchange heat, and the flue gas generated by the combustion of the fuel and the air is condensed to obtain liquid water and CO2, and the fuel is the fuel that has not completely reacted at the outlet of the SOFC stack module.

2. The anode tail gas recirculation SOFC power generation system according to claim 1, characterized in that: A portion of the anode tail gas at the outlet of the SOFC stack module passes through the electric control valve, the reformer and the fuel preheater in sequence, and is mixed with the desulfurized natural gas before entering the circulation fan and the fuel pipeline.

3. The anode tail gas recirculation SOFC power generation system according to claim 1, characterized in that: The catalytic burner adopts a heat exchange design, and the catalytic burner includes a heat exchanger and a catalyst. The heat exchanger includes a fuel channel and an air channel. The fuel channel is provided with a fuel inlet, an O2 inlet, a fuel outlet and the catalyst for catalytic combustion, and the air channel is provided with an air inlet and an air outlet. After a portion of the anode exhaust gas from the outlet of the SOFC stack module enters the fuel channel of the catalytic burner, it burns with O2 under the action of the catalyst to release heat, and heats the air from the outlet of the SOFC stack module in the air channel through the heat exchanger.

4. The anode tail gas recirculation SOFC power generation system according to claim 1, characterized in that: When the system is operating at rated speed, the first stop valve is in an open state and the second stop valve is in a closed state. The flue gas at the outlet of the fuel channel of the catalytic burner passes through the first stop valve, the reformer and the condenser in sequence to react and obtain CO2. The air at the outlet of the air channel of the catalytic burner passes through the starting burner and exchanges heat with the air at the outlet of the fan in the air preheater. The flue gas includes water vapor and CO2.

5. The anode tail gas recirculation SOFC power generation system according to claim 1, characterized in that: The start-up burner is provided with an ignition device, which is used to activate the start-up burner. The start-up burner burns the fuel and air introduced into the SOFC power generation system to make the temperature in the catalytic burner reach the temperature required for catalytic combustion.

6. The anode tail gas recirculation SOFC power generation system according to claim 1, characterized in that: The reformer adopts a heat exchange type, and is provided with a cold side channel and a hot side channel. The cold side channel is filled with a reforming catalyst, and the hot side channel is respectively connected to the fuel channel outlet of the catalytic burner and the inlet of the condenser; when the system is operated at rated speed, the flue gas at the fuel channel outlet of the catalytic burner provides a heat source for the fuel reforming reaction in the cold side channel.

7. The anode tail gas recirculation SOFC power generation system according to claim 1, characterized in that: The steam generator adopts electric heating. During the heating and cooling stages of the SOFC power generation system, the flow rate of water vapor is 2.5 times the fuel flow rate. During the power generation stage of the SOFC power generation system, the flow rate of water vapor has a water-to-carbon ratio of 2 to 3 at the inlet of the reformer. During the rated power generation stage of the SOFC power generation system, the steam generator is in a closed state.

8. The anode tail gas recirculation SOFC power generation system according to claim 1, characterized in that: The first stop valve is arranged on the pipeline between the fuel channel outlet pipeline tee of the catalytic burner and the hot side inlet pipeline tee of the reformer, the second stop valve is arranged on the pipeline between the flue gas outlet pipeline tee of the startup burner and the hot side inlet pipeline tee of the reformer, and the third stop valve is arranged on the pipeline between the fuel channel outlet tee of the catalytic burner and the fuel inlet of the startup burner.

9. A method for operating an anode tail gas recirculation SOFC power generation system, characterized in that: Applied to the anode tail gas recirculation SOFC power generation system according to any one of claims 1 to 8, the method comprises the following contents: (1) closing the first stop valve of the system, opening the second stop valve, the third stop valve and the blower of the system, introducing natural gas into the system and turning on the circulation blower of the system, and when air and the natural gas enter the start-up burner of the system, starting the ignition device in the start-up burner to activate the start-up burner to burn the natural gas; (2) when the temperature of the reformer and the SOFC stack module of the system exceeds 300° C., and the temperature of the fuel line of the system exceeds 150° C., starting the steam generator of the system to supply steam to the system to prevent carbon deposition in the reformer and the SOFC stack module; (3) When the outlet temperature of the fuel channel of the catalytic burner of the system exceeds 550° C., the first stop valve is opened, O 2 is introduced into the catalytic burner, and the second stop valve is closed; (4) When the SOFC stack module reaches the power generation temperature, adjust the flow rate of the natural gas, the flow rate of the water vapor, the speed of the circulating fan, and the opening of the electric control valve of the system, monitor the fuel utilization rate of the SOFC stack module, and adjust the flow rate of the O2. When the current of the system reaches the rated value, turn off the steam generator; (5) when the system is in a rated operation stage, separating CO2 from a condenser of the system; (6) regulating the flow rate of the natural gas according to the current rate and fuel utilization rate of the SOFC stack module, opening the steam generator and adjusting the flow rate of the water vapor, the speed of the circulating fan, the opening of the electronically controlled valve, and the flow rate of the O2; (7) When the outlet temperature of the fuel channel of the catalytic burner drops to 550°C, open the second shut-off valve and stop supplying the O2 into the catalytic burner; when the temperatures of the reformer and the SOFC stack module both drop to 300°C, turn off the steam generator; when the temperatures of the reformer and the SOFC stack module both drop to 100°C, turn off the circulation fan, stop supplying the natural gas into the system, and turn off the fan.

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