CN114765266A - SOFC (solid oxide fuel cell) combined heat and power system capable of improving heat efficiency and optimizing water management - Google Patents

Abstract

The invention relates to a SOFC (solid oxide fuel cell) combined heat and power system capable of improving heat efficiency and optimizing water management, wherein combustion tail gas preheats air, reforming reaction, fuel, reforming water and domestic water in sequence, so that the comprehensive recycling of energy and water contained in the combustion tail gas is realized, the water and heat management of the system is optimized, and the thermoelectric efficiency of the system is effectively improved. The system optimizes the layout of components and a heat exchange process, adds a waste heat recovery heat exchanger and a condenser, and uses cooling water to recover heat energy in tail gas so as to realize external heat supply; the water in the tail gas is recycled by adding a water storage tank, a circulating pipeline and an electromagnetic control valve. The invention can optimize the water and heat management in the system operation process, greatly improve the heat efficiency of the system, reduce the water consumption of the system and reduce the operation cost.

Description

A SOFC Combined Heat and Power System to Improve Thermal Efficiency and Optimize Water Management

technical field

The invention relates to the technical field of SOFC combined heat and power system operation, in particular to a SOFC combined heat and power system that improves thermal efficiency and optimizes water management.

Background technique

SOFC (Solid Oxide Fuel Cell) is a new, high-efficiency, high-temperature fuel cell with good fuel adaptability and low pollutant emission, which has broad application prospects in distributed power generation systems and mobile power sources.

SOFC is a high-temperature fuel cell, the core working temperature is usually between 700-800 ℃, and the temperature of the stack exhaust gas can generally reach above 750 ℃, and contains some fuel gas that has not been fully reacted. The stack exhaust gas is burned to supply heat to the reformer, and after heat exchange with the incoming gas, part of the heat in the combustion exhaust gas is recycled, and the final exhaust temperature can be reduced to about 400 °C. In order to improve the overall efficiency of SOFC power generation system, it is usually designed as a combined heat and power system, and the heat in the exhaust gas after combustion is further recovered by cooling water, and the hot water produced can be used for production and life. can be lowered to below 100°C. However, the dew point temperature of the exhaust gas after combustion is generally lower than 60 °C, and the latent heat of evaporation of water in the exhaust gas cannot be effectively recovered. Effective recovery and utilization of this part of the energy can greatly improve the thermal efficiency of the system.

On the other hand, when carbon-based fuel is used as the fuel of the SOFC system, the fuel needs to be reformed before entering the stack, and the reforming process needs to consume a lot of water. The storage, supply and management of reformed water increase the complexity and cost of system operation. Reasonable recycling and utilization of water in tail gas can optimize system water management.

SUMMARY OF THE INVENTION

In view of the problems existing in the prior art, the present invention provides a SOFC cogeneration system that improves thermal efficiency and optimizes water management. Taking the existing SOFC power generation system as a benchmark system, by introducing exhaust gas condensation and waste heat recovery subsystems, reforming Water circulation subsystem, improving the exhaust heat exchange subsystem can improve the heat exchange performance of the system, realize the recovery of the latent heat of vaporization of water in the exhaust gas, and at the same time provide the reformer with the reforming water required for reforming, and optimize the water and heat management of the system .

In order to achieve the above purpose, the present invention provides a SOFC cogeneration system for improving thermal efficiency and optimizing water management, including a reforming subsystem, a SOFC power generation subsystem, a combustion subsystem, a tail gas heat exchange subsystem, tail gas condensation and waste heat recovery. Subsystem and reforming water cycle sub-system;

The reforming subsystem performs a reforming reaction to supply fuel to the SOFC power generation subsystem;

The SOFC power generation subsystem is used to generate an electrochemical reaction, and the anode gas and cathode gas generated after the reaction are burned in the combustion subsystem to generate combustion exhaust gas;

The reformed water circulation subsystem is used for supplying reformed water to the reforming subsystem;

The combustion exhaust gas enters the exhaust heat exchange subsystem, preheats the air supplied to the SOFC power generation subsystem, and then enters the reforming subsystem to provide the heat required for reforming, and then enters the exhaust heat exchange subsystem After preheating the fuel gas supplied to the reforming subsystem and the reforming water supplied to the reforming subsystem in sequence, they enter the exhaust gas condensation and waste heat recovery subsystem;

The exhaust gas condensation and waste heat recovery subsystem recovers the waste heat in the combustion exhaust gas and then condenses and supplies the condensed water to the reformed water circulation subsystem.

Further, the exhaust gas heat exchange subsystem includes an air preheater, a fuel preheater and a reforming water preheater, and the combustion exhaust gas passes through the air preheater, the fuel preheater and the reforming water preheater in sequence, and sequentially The air supplied to the SOFC power generation subsystem, the gas supplied to the reforming subsystem, and the reformed water supplied to the reforming subsystem are preheated.

Further, the exhaust gas condensation and waste heat recovery subsystem includes a cooling water pump, a condenser and a waste heat recovery heat exchanger; the cold water pumped by the cooling water pump is preheated by the condenser, and then exchanges with the combustion exhaust gas through the waste heat recovery heat exchanger. Hot water supply is provided after being heated; the exhaust gas enters the condenser after heat exchange through the waste heat recovery heat exchanger to generate condensed water and supply it to the reforming water circulation subsystem.

Further, the reformed water circulation subsystem includes a water storage tank, a water replenishment solenoid valve and an electromagnetic three-way valve; the condensed water generated by the condenser flows into the water storage tank through the electromagnetic three-way valve for storage; When the water is less than the required reforming water, open the water replenishment solenoid valve to supplement the reforming water for the water storage tank; when the recovered condensed water is more than the reforming water required for reforming, the excess condensed water passes through the Solenoid three-way valve discharge.

Further, the anode tail gas output pipeline of the SOFC power generation subsystem is set with an anode circulation diverter valve, and the anode tail gas is diverted, and one part enters the reformer of the reforming subsystem to participate in the reforming reaction again, and the other part directly enters the combustion subsystem. The burner is mixed with the cathode exhaust gas.

Further, the reforming subsystem includes a reformer, and the preheated fuel is supplied through the fuel preheater, the preheated water is supplied through the reformed water preheater, and the anode is supplied through the anode. The circulating diverter valve supplies the anode tail gas for the reforming reaction, and the tail gas is connected to provide the heat required for the reforming.

Further, the structure is a two-layer layout, the air preheater, the fuel preheater, the reforming water preheater and the waste heat recovery heat exchanger are located on the upper layer, and the stack, the burner and the regenerator of the SOFC power generation subsystem are located on the upper layer. The unit is located on the lower level.

Further, the stack of the SOFC power generation subsystem is arranged on one side, the burner and the reformer are arranged side by side on the other side; the inlet of the anode of the SOFC power generation subsystem is opposite to the outlet of the reformer Set, connect directly through pipeline;

The outlet of the anode of the SOFC power generation subsystem is arranged between the burner and the reformer, and is respectively connected to the anode gas inlet of the burner and the anode tail gas inlet of the reformer through branch pipes;

The cathode outlet of the SOFC power generation subsystem is arranged opposite to the cathode gas inlet of the burner, and is directly connected through a pipeline.

Further, the fuel preheater and the reforming water preheater are integrally arranged above the reformer, the heat exchange pipelines are connected in cascade, the inlet of the heat exchange pipeline is arranged at the bottom, and is connected with the reformer. The heat exchange outlets are arranged opposite to each other and are connected by pipelines; the inlet end of the fuel preheater for connecting the fuel compressor/fuel pump is arranged on the side, and the fuel compressor/fuel pump is arranged on the side of the fuel preheater. side; the reforming water preheater is connected to the water storage tank through a reforming water pump, the reforming water pump is arranged on the side of the reforming water preheater, and the water storage tank is placed separately.

Further, the air preheater is arranged above the burner and the stack, the air inlet end is connected to the air compressor, the air outlet is arranged below and opposite the cathode inlet of the stack, connected by pipelines, and the preheater works. The mass inlet is arranged below and opposite to the outlet of the burner, and is connected through a pipeline;

The waste heat recovery heat exchanger is arranged above the stack, on the same side as the fuel preheater and the reforming water preheater. Connection, the outlet of the heat exchange working medium of the waste heat recovery heat exchanger is connected to the condenser, and the condenser is arranged separately.

The above-mentioned technical scheme of the present invention has the following beneficial technical effects:

(1) The present invention takes the conventional SOFC power generation system as the benchmark system for improvement, adds the exhaust gas condensation and waste heat recovery subsystem, the reforming water circulation subsystem, and optimizes the exhaust gas heat exchange subsystem, which can simultaneously realize the latent heat of vaporization of the water in the exhaust gas. Recycling and recycling of water in exhaust gas, optimizing water and heat management during system operation, improving system thermal efficiency and reducing system operating costs.

(2) The system components of the present invention adopt a modular and compact design, the stack, the burner and the reformer are closely arranged in the lower layer; the air heat exchanger is located above the stack and the burner; the fuel heat exchanger and the reforming water heat exchange The waste heat recovery device and the air heat exchanger are arranged on the upper layer; this layout method can reduce the flow distance of the working medium between different components, thereby reducing the heat dissipation during the flow process; at the same time, it can optimize the overall temperature distribution of the system and improve the overall performance. .

(3) SOFC anode tail gas of the present invention is shunted through the anode circulation diverter valve, and a part returns to the inside of the reformer to participate in the reforming reaction again, and the other part directly enters the burner to mix and burn with the cathode tail gas; the combustion tail gas first exchanges heat with air, Reduce the temperature, and then directly exchange heat with the reformer to provide the heat required for reforming. By setting a temperature sensor in the reformer and fully theoretical calculation before design, the working temperature of the reformer can be ensured. Within a reasonable range (generally not higher than 900 ℃). In addition, through the design of the control system, the system can be adjusted to a reasonable range when it deviates from the working range. Make sure that the operating temperature of the reformer is within a reasonable range.

(4) In the present invention, the exhaust gas path is reasonably set according to the heat exchange temperature, the size of the heat exchange amount and the heat exchange difficulty in turn, and the exhaust gas path is reasonably set according to the size of the required heat. Water and domestic water are used in five stages to maximize the use of exhaust heat, and to ensure that the heat exchange components work within an efficient and suitable working range.

Description of drawings

Figure 1 is a schematic diagram of the SOFC cogeneration system; wherein: 1. Air compressor; 2. Fuel compressor/fuel pump; 3. Reforming water pump; 4. Air preheater; 5. Fuel preheater; 6. Reforming water preheater; 7. Reformer; 8. Burner; 9. Anode circulation diverter valve; 10. Cooling water pump; 11. Condenser; 12. Waste heat recovery heat exchanger; 13. Electromagnetic three-way valve; 14. Water replenishment solenoid valve; 15. Water storage tank; 16. Inverter.

Figure 2 is a three view of the components and piping layout of the SOFC cogeneration system.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the specific embodiments and the accompanying drawings. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. Also, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concepts of the present invention.

The present invention provides a SOFC cogeneration system that improves thermal efficiency and optimizes water management. It includes 6 subsystems: reforming subsystem, SOFC power generation subsystem, combustion subsystem, exhaust heat exchange subsystem, exhaust gas condensation and waste heat recovery subsystem and reforming water circulation subsystem. The structure of each subsystem is combined with Figure 1.

The reforming subsystem, including the reformer 7, performs reforming reaction to supply fuel to the SOFC power generation subsystem, the heat of the reforming reaction is provided by the combustion exhaust gas, and the required fuel and water are preheated by the combustion exhaust gas. By setting a temperature sensor in the reformer and making sufficient theoretical calculations before design, it can be ensured that the working temperature of the reformer is within a reasonable range (generally not higher than 900°C). In addition, through the design of the control system, the air flow is adjusted based on the temperature detected by the temperature sensor, so that the system can adjust itself to a reasonable range when it deviates from the working area.

The SOFC power generation subsystem includes SOFC, inverter 16 . The SOFC cathode inlet is connected to the air preheater 4; the SOFC anode inlet is connected to the reformer 7; the cathode exhaust gas of the SOFC directly enters the burner 8, and the anode exhaust gas passes through the anode circulation diverter valve 9 and partially enters the burner 8 for combustion; The SOFC stack is connected to the inverter 16, which converts direct current to alternating current for output.

The combustion subsystem includes a burner 8, and the cathode and anode exhaust gas is passed through to the inside for combustion to generate combustion exhaust gas. The combustion exhaust gas is supplied to the exhaust gas heat exchange subsystem for heat recovery and utilization.

The exhaust heat exchange subsystem includes an air compressor 1 , a fuel compressor/fuel pump 2 , a reforming water pump 3 , an air preheater 4 , a fuel preheater 5 , and a reforming water preheater 6 . The air compressor 1 is connected in series with the air preheater 4; the air at ambient temperature and pressure is boosted by the air compressor 1, and then heat-exchanged in the air preheater 4, and then enters the SOFC cathode after being heated to the set temperature. The fuel compressor/fuel pump 2 is connected to the fuel preheater 5; the fuel at ambient temperature and pressure is boosted by the fuel compressor/fuel pump 2, and then heat-exchanged in the fuel preheater 5 to heat up to the set temperature Then enter the reformer 7 for catalytic reforming. The reforming water pump 3 is connected with the reforming water preheater 6; the reforming water under the ambient temperature and the ambient pressure is boosted by the reforming water pump 3, and then the heat is exchanged in the reforming water preheater 6, and the temperature is raised to the set temperature Then enter the reformer 7 for catalytic reforming. The exhaust gas discharged from the burner 8 exchanges heat with the air preheater 4, the reformer 7, the fuel preheater 5, and the reformed water preheater 6 in sequence, so as to realize the graded utilization of the heat of the exhaust gas.

The exhaust gas condensation and waste heat recovery subsystem includes a cooling water pump 10 , a condenser 11 , and a waste heat recovery heat exchanger 12 . The exhaust gas after the cascade heat exchange first enters the waste heat recovery heat exchanger 12 for heat exchange to cool down to the set temperature; the exhaust gas after the waste heat recovery enters the condenser 11 for condensation, the distilled water obtained by condensation enters the reforming water circulation subsystem, and the rest of the exhaust gas directly Emissions into the atmosphere. The heat exchange working medium between the waste heat recovery heat exchanger 12 and the condenser 11 is cooling water; the cooling water at ambient temperature and pressure is first boosted by the cooling water pump 10, and then enters the condenser 11 and the waste heat recovery heat exchanger 12 for exchange. Heat, absorb heat and heat up to the standard of domestic hot water or industrial hot water for external use.

The reformed water circulation subsystem includes a water storage tank 15 , a water replenishment solenoid valve 14 and an electromagnetic three-way valve 13 . The condensed water obtained in the condenser 11 flows into the water storage tank 15 through the three-way solenoid valve 13 for storage; the distilled water for catalytic reforming is stored in the water storage tank 15; the water storage tank contains two inlets, one is connected to the electromagnetic three-way valve. 13. A connection to the water replenishment solenoid valve 14. The size of the amount of condensed water and the amount of reforming water is determined by the type of fuel. When the condensed water obtained by condensation is more than the reforming water required for reforming, the water replenishment solenoid valve 14 is closed, and the excess condensed water is discharged through the electromagnetic three-way valve 13; When the condensed water obtained by condensation is less than the reforming water required for reforming, the water replenishment solenoid valve 14 is opened to provide additional reforming water for the water storage tank 15 ; the outlet of the water storage tank 15 is connected to the reforming water pump 3 .

The post-combustion exhaust gas from the burner 8 exchanges heat with the air preheater 2 first, and then exchanges heat with the reformer 7; this design can ensure that the reformer works in a suitable temperature range and the reforming reaction catalyst At the same time, it can prevent the additional air from reducing the performance of the system; the post-combustion exhaust gas after heat exchange with the reformer enters the fuel preheater 4 and the reforming water preheater 6 in turn for heat exchange and heat recovery; The exhaust gas from the whole water preheater 6 enters the waste heat recovery heat exchanger 12; then enters the condenser 11 for condensation to achieve water-gas separation, the gaseous exhaust gas is directly discharged, and the liquid water enters the water storage tank 15 through the electromagnetic three-way valve 13. The cooling water for waste heat recovery passes through the cooling water pump 10 and successively enters the condenser 11 and the waste heat recovery heat exchanger 12 for heat exchange; the hot water obtained from the heat exchange can be used for production and life.

According to the above SOFC cogeneration system, in order to reduce the heat dissipation of the thermal working medium, reduce the length of the pipeline, and sort out the connection relationship between the various components. The air compressor 1 is connected to the cathode of the SOFC after being connected in series with the air preheater 2; the fuel compressor/fuel pump 3 is connected to the reformer inlet after being connected in series with the fuel preheater 4; the reforming water pump 5 is connected to the reforming water preheating After being connected in series, the reformer 6 is connected to the reformer inlet; the reformer outlet is connected to the SOFC anode; the SOFC stack is connected to the inverter 16 to convert direct current into alternating current output; the SOFC cathode exhaust gas directly enters the burner 8; After the gas enters the anode circulation diverter valve 9, part of it enters the burner for combustion, and the other part returns to the reformer to participate in the reforming reaction to realize the anode tail gas circulation.

According to the above connection relationship, the pipeline layout is optimized. Figure 2 is a three-view diagram of the high-temperature components and pipeline layout in the optimized system. The components located in the lower layer are: the stack, the burner 8, and the reformer 7; The components on the upper layer are: air heat exchanger 4 , fuel heat exchanger 5 , reforming water heat exchanger 6 , and waste heat recovery device 7 . The air heat exchanger is located above the burner and the stack; the fuel heat exchanger and the reformed water heat exchanger are integrated and located above the reformer; the waste heat recovery device is located above the single stack.

Further, the stack is arranged on one side, and the burner 8 and the reformer 7 are arranged side by side on the other side. The inlet of the anode of the SOFC power generation subsystem is arranged opposite to the outlet of the reformer 7, and is directly connected by a pipeline. The outlet of the anode of the SOFC power generation subsystem is arranged between the burner 8 and the reformer 7, and is respectively connected to the anode gas inlet of the burner 8 and the anode exhaust gas inlet of the reformer 7 through branch pipes. The cathode outlet of the SOFC power generation subsystem is arranged opposite to the cathode gas inlet of the burner 8, and is directly connected through a pipeline.

The fuel preheater 5 and the reforming water preheater 6 are integrally arranged and located above the reformer 7. The fuel preheater 5 is connected in cascade with the heat exchange pipeline of the reforming water preheater 6, and the heat exchange pipeline The inlet is arranged at the bottom, opposite to the heat exchange outlet of the reformer 7, and is connected through a pipeline. The inlet end of the fuel preheater 5 for connecting to the fuel compressor/fuel pump 2 is provided on the side, and the fuel compressor/fuel pump 2 is provided on the side of the fuel preheater 5 . The reforming water preheater 6 is connected to the water storage tank 15 through the reforming water pump 3, the reforming water pump 3 is arranged on the side of the reforming water preheater 6, and the water storage tank 15 is placed separately.

The air preheater 4 is arranged above the burner 8 and the stack, the air inlet end is connected to the air compressor 1, and the air outlet is arranged at the bottom opposite to the cathode inlet of the stack, connected by a pipeline, and the inlet of the preheating working medium It is arranged below and opposite to the outlet of the burner 8, and is connected through a pipeline.

The waste heat recovery heat exchanger 12 is arranged above the stack, on the same side as the fuel preheater 5 and the reforming water preheater 6, and the heat exchange working medium inlet is opposite to the heat exchange working medium outlet of the reforming water preheater 6 , through the pipeline connection, the outlet of the heat exchange working medium of the waste heat recovery heat exchanger 12 is connected to the condenser 11, and the condenser 11 is arranged separately.

The effect of the present invention will be further described below in conjunction with the simulation results. The simulated initial conditions and results of the optimized system based on the method of improving the thermal efficiency of the SOFC cogeneration system and optimizing the water management are shown in Table 1 and Table 2, respectively.

Table 1 System initial conditions

Table 2 System simulation results

It can be seen from Table 1 and Table 2 that in one embodiment, methanol is used as the fuel, the fuel utilization rate of the system is 70%, the rated voltage is 0.7V, and the rated power is 30kW. Under rated operating conditions, the power generation efficiency of this system is 31.96%, the thermal efficiency is 47.17%, and the total efficiency is 79.13%; compared with the reference system, the thermal efficiency is increased by 14.35%. The flow rate of reforming water is 525mol/h, and the flow rate of condensed water is 906mol/h, which can satisfy the self-circulation of water in the system.

To sum up, the present invention relates to a SOFC combined heat and power system that improves thermal efficiency and optimizes water management. Combustion tail gas preheats air, reforming reaction, fuel, reforming water, and domestic water in sequence, and realizes the reduction of all combustion tail gas. The comprehensive recovery and utilization of the contained energy and water optimizes the water and heat management of the system, and effectively improves the thermoelectric efficiency of the system. The system optimizes the component layout and heat exchange process, adds waste heat recovery heat exchangers and condensers, and uses cooling water to recover the heat energy in the exhaust gas to achieve external heat supply; Recycling of water in exhaust gas. The invention can optimize the water and heat management during the operation of the system, greatly improve the thermal efficiency of the system, reduce the water consumption of the system and reduce the operation cost.

It should be understood that the above-mentioned specific embodiments of the present invention are only used to illustrate or explain the principle of the present invention, but not to limit the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and scope of the present invention should be included within the protection scope of the present invention. Furthermore, the appended claims of this invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalents of such scope and boundaries.

Claims (10)

1. An SOFC (solid oxide fuel cell) combined heat and power system for improving heat efficiency and optimizing water management is characterized by comprising a reforming subsystem, an SOFC power generation subsystem, a combustion subsystem, a tail gas heat exchange subsystem, a tail gas condensation and waste heat recovery subsystem and a reforming water circulation subsystem;

the reforming subsystem carries out reforming reaction and supplies fuel to the SOFC power generation subsystem;

the SOFC power generation subsystem is used for generating electrochemical reaction, and anode gas and cathode gas generated after the reaction are combusted in the combustion subsystem to generate combustion tail gas;

the reforming water circulation subsystem is used for supplying reforming water to the reforming subsystem;

the combustion tail gas enters the tail gas heat exchange subsystem, preheats air fed into the SOFC power generation subsystem, then enters the reforming subsystem to provide heat required by reforming, enters the tail gas heat exchange subsystem to preheat fuel gas fed into the reforming subsystem and reforming water fed into the reforming subsystem in sequence, and then enters the tail gas condensation and waste heat recovery subsystem;

and the tail gas condensation and waste heat recovery subsystem recovers waste heat in the combustion tail gas and then condenses to obtain condensed water which is supplied to the reforming water circulation subsystem.

2. The SOFC cogeneration system of claim 1, wherein the tail gas heat exchange subsystem comprises an air preheater (4), a fuel preheater (5), and a reforming water preheater (6), and wherein the combustion tail gas sequentially passes through the air preheater, the fuel preheater, and the reforming water preheater, sequentially preheating air fed to the SOFC power generation subsystem, fuel gas fed to the reforming subsystem, and reforming water fed to the reforming subsystem.

3. The SOFC cogeneration system according to claim 2, wherein the exhaust gas condensation and waste heat recovery subsystem comprises a cooling water pump (10), a condenser (11) and a waste heat recovery heat exchanger (12); cold water pumped by a cooling water pump (10) is preheated by the condenser (11), and then is subjected to heat exchange with combustion tail gas by a waste heat recovery heat exchanger (12) to provide hot water supply; and tail gas enters the condenser (11) after being subjected to heat exchange by the waste heat recovery heat exchanger (12) to generate condensed water and is supplied to the reforming water circulation subsystem.

4. The SOFC cogeneration system of claim 3, wherein the reforming water circulation subsystem comprises a water storage tank (15), a moisturizing solenoid valve (14), and a solenoid three-way valve (13); condensed water generated by the condenser (11) flows into the water storage tank through an electromagnetic three-way valve to be stored; when the recovered condensed water is less than the required reformed water, a water replenishing electromagnetic valve (14) is opened to replenish the reformed water for the water storage tank; when the recovered condensed water is more than the reforming water required for reforming, the excess condensed water is discharged through the electromagnetic three-way valve (13).

5. The SOFC cogeneration system according to claim 4, characterized in that an anode circulation diverter valve (9) is arranged on an anode tail gas output pipeline of the SOFC power generation subsystem, and the anode tail gas is diverted, one part of the anode tail gas enters a reformer (7) of the reforming subsystem to participate in the reforming reaction again, and the other part of the anode tail gas directly enters a combustor (8) of the combustion subsystem to be mixed with the cathode tail gas for combustion.

6. The SOFC cogeneration system according to claim 5, wherein the reforming subsystem comprises a reformer (7), preheated fuel is supplied through the fuel preheater (5), preheated water is supplied through the reforming water preheater (6), anode tail gas is supplied through the anode cycle diverter valve (9) to perform the reforming reaction, and the tail gas is supplied to provide heat required for reforming.

7. The SOFC cogeneration system according to claim 6, wherein the structure is a two-layer layout, the air preheater (4), the fuel preheater (5) and the reforming water preheater (6) and the heat recovery heat exchanger (12) are located on the upper layer, and the stack, the burner (8) and the reformer (7) of the SOFC power generation subsystem are located on the lower layer.

8. The SOFC cogeneration system according to claim 7, wherein the cell stack of the SOFC power generation subsystem is disposed on one side, and the combustor (8) and the reformer (7) are disposed in parallel on the other side; the inlet of the SOFC power generation subsystem anode is opposite to the outlet of the reformer (7) and is directly connected with the reformer through a pipeline;

the outlet of the SOFC power generation subsystem anode is arranged between the combustor (8) and the reformer (7) and is respectively connected to the anode gas inlet of the combustor (8) and the anode tail gas inlet of the reformer (7) through branch pipelines;

and the cathode outlet of the SOFC power generation subsystem is opposite to the cathode gas inlet of the combustor (8) and is directly connected with the cathode gas inlet of the combustor through a pipeline.

9. The SOFC cogeneration system according to claim 7 or 8, wherein the fuel preheater (5) and the reforming water preheater (6) are integrally disposed above the reformer (7), and the heat exchange pipes are connected in cascade, and the inlets of the heat exchange pipes are disposed at the bottom, opposite to the heat exchange outlets of the reformer (7), and connected by pipes; the inlet end of the fuel preheater (5) for connecting a fuel compressor/fuel pump (2) is arranged at the side, and the fuel compressor/fuel pump (2) is arranged at the side of the fuel preheater (5); reforming water pre-heater (6) are connected to through reforming water pump (3) water storage tank (15), and reforming water pump (3) set up the side of reforming water pre-heater (6), water storage tank (15) are placed alone.

10. SOFC cogeneration system according to claim 9, characterised by the fact that the air preheater (4) is placed above the burner (8) and the cell stack, the air inlet end is connected to the air compressor (1), the air outlet is placed below opposite the cathode inlet of the cell stack and connected by a pipe, the preheated working medium inlet is placed below opposite the outlet of the burner (8) and connected by a pipe;

the waste heat recovery heat exchanger (12) is arranged above the electric pile, is arranged at the same side with the fuel preheater (5) and the reforming water preheater (6), the heat exchange working medium inlet is opposite to the heat exchange working medium outlet of the reforming water preheater (6), and is connected to the condenser (11) through a pipeline, the heat exchange working medium outlet of the waste heat recovery heat exchanger (12) is connected to the condenser (11), and the condenser (11) is arranged independently.

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