Solid oxide fuel cell double closed combined cycle power generation system and operation method

Abstract

The present invention discloses a double closed combined cycle power generation system of solid oxide fuel cell and an operation method, the system is composed of solid oxide fuel cell, reformer, steam turbine, condenser, water separator, CO2 separator, heat exchanger, splitter, combiner, supercharging equipment, compressor, and water pump. The system refluxes all the anode tail gas of solid oxide fuel cell, and the system fuel utilization rate is 100%; the anode and cathode tail gas of solid oxide fuel cell are used as high temperature heat sources of steam turbine closed cycle, driving steam cycle power generation, forming a double closed combined cycle of solid oxide fuel cell and steam turbine, and the power generation efficiency is greatly improved; and the anode tail gas can be separated into water and CO2 in an orderly manner through the water separator and CO2 separator, and discharged out of the system.

Description

Technical Field

[0001] The present invention belongs to the technical field of cogeneration, and in particular relates to a solid oxide fuel cell double closed combined cycle power generation system and an operation method. Background Art

[0002] Solid Oxide Fuel Cell (SOFC) is a new type of high-efficiency and low-carbon energy utilization technology. The operating temperature of the fuel cell is 700-1000℃, and the waste heat utilization value is high. The solid oxide fuel cell can form a combined cycle with gas turbines to improve the power generation efficiency. However, the fuel utilization rate of solid oxide fuel cells is limited, generally 60-80%. How to improve the fuel utilization rate of solid oxide fuel cells has always been a technical problem. Summary of the invention

[0003] The purpose of the present invention is to provide a solid oxide fuel cell dual closed combined cycle power generation system and operation method, which can greatly improve the fuel utilization rate of the solid oxide fuel cell by orderly treating the anode tail gas of the fuel cell stack and then returning it to the fuel cell stack inlet to form a closed cycle.

[0004] The present invention is implemented as follows: a solid oxide fuel cell double closed combined cycle power generation system, comprising a solid oxide fuel cell, a reformer, a steam turbine, a condenser, a water separator, a CO 2 A separator, a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a first flow splitter, a first flow combiner, a second flow combiner, a booster, a compressor, a first water pump, and a second water pump;

[0005] The outlet of the first water pump is connected to the low-temperature fluid inlet of the first heat exchanger, the low-temperature fluid outlet of the first heat exchanger is connected to the inlet of the reformer, and the outlet of the reformer is connected to the first inlet of the first combiner;

[0006] The fuel outlet of the supercharging device is connected to the inlet of the reformer;

[0007] The anode tail gas outlet of the solid oxide fuel cell is connected to the high temperature fluid inlet of the second heat exchanger, the high temperature fluid outlet of the second heat exchanger is connected to the high temperature fluid inlet of the first heat exchanger, the high temperature fluid outlet of the first heat exchanger is connected to the inlet of the water separator, and the anode tail gas outlet of the water separator is connected to the CO 2 The inlet of the separator; the CO 2 The anode tail gas outlet of the separator is connected to the second inlet of the first combiner, and the anode tail gas outlet of the first combiner is connected to the anode inlet of the solid oxide fuel cell;

[0008] The outlet of the compressor is connected to the low-temperature fluid inlet of the fourth heat exchanger, the low-temperature fluid outlet of the fourth heat exchanger is connected to the cathode inlet of the solid oxide fuel cell, the cathode outlet of the solid oxide fuel cell is connected to the high-temperature fluid inlet of the third heat exchanger, the high-temperature fluid outlet of the third heat exchanger is connected to the high-temperature fluid inlet of the fourth heat exchanger, and the high-temperature fluid outlet of the fourth heat exchanger is connected to the external environment;

[0009] The outlet of the second water pump is connected to the inlet of the first splitter, the first outlet of the first splitter is connected to the low-temperature fluid inlet of the third heat exchanger, the low-temperature fluid outlet of the third heat exchanger is connected to the first inlet of the second combiner, the second outlet of the first splitter is connected to the low-temperature fluid inlet of the second heat exchanger, the low-temperature fluid outlet of the second heat exchanger is connected to the second inlet of the second combiner, the outlet of the second combiner is connected to the inlet of the steam turbine, the outlet of the steam turbine is connected to the high-temperature fluid inlet of the condenser, and the high-temperature fluid outlet of the condenser is connected to the inlet of the second water pump;

[0010] The electricity generation outlet of the solid oxide fuel cell is connected to an electricity user, and the heat generation outlet thereof is connected to a heat user and the reformer;

[0011] The heat generating outlet of the water separator is connected to a heat user, and the water outlet is connected to the inlet of the first water pump for recycling, or connected to a water user, or connected to the external environment.

[0012] Furthermore, the system also includes a second splitter, whose inlet is connected to the anode tail gas outlet of the solid oxide fuel cell, whose first outlet is connected to the inlet of the reformer, and whose second outlet is connected to the high-temperature fluid inlet of the second heat exchanger.

[0013] Furthermore, the water separator is a condenser, a water silica gel adsorber, a water calcium-based adsorber or an activated alumina adsorber.

[0014] Furthermore, the CO 2 The separator is a calcium-based adsorber or an amine-based adsorber.

[0015] Furthermore, the boosting device adopts a water pump or a compressor according to the material state of the hydrocarbon fuel.

[0016] To achieve the above-mentioned object of the invention, the present invention also provides an operation method of a solid oxide fuel cell double closed combined cycle power generation system, comprising the following processing flow:

[0017] Air flow processing flow: air becomes high-pressure air after passing through the compressor, and the high-pressure air enters the fourth heat exchanger and is preheated by the cathode tail gas of the fuel cell passing through the third heat exchanger and then converted into preheated air, and the preheated air enters the cathode of the solid oxide fuel cell and participates in the electrochemical reaction and is converted into cathode tail gas, and the cathode tail gas passes through the third heat exchanger and transfers part of the heat to the water in the steam turbine cycle, and then passes through the fourth heat exchanger and transfers part of the heat to the air and then is discharged into the environment;

[0018] Hydrocarbon fuel flow path processing flow: Hydrocarbon fuel enters the reformer through the booster device to participate in the hydrocarbon fuel reforming reaction. The reformed gas generated by the reforming reaction enters the first combiner and passes through the second heat exchanger, the first heat exchanger, the water separator, the CO 2 The anode tail gas of the fuel cell of the separator is combined into the anode fuel gas, and the anode fuel gas enters the anode of the solid oxide fuel cell to participate in the electrochemical reaction;

[0019] Water flow path processing flow: water enters the first heat exchanger through the first water pump, is heated and evaporated to convert into hot water vapor, and the hot water vapor enters the reformer to participate in the hydrocarbon fuel reforming reaction;

[0020] Fuel cell anode tail gas flow path processing process: The anode tail gas discharged from the solid oxide fuel cell enters the second heat exchanger, releases heat and turns into the second anode tail gas, enters the first heat exchanger, releases heat and turns into the third anode tail gas, and then enters the water separator, removes the electrochemical reaction product water and turns into the fourth anode tail gas, and enters the CO 2 Separator, to separate the electrochemical product CO 2 Then it is converted into the fifth anode tail gas and enters the first combiner, and is combined with the reformed gas to form the anode fuel gas and flows back to the anode inlet of the solid oxide fuel cell;

[0021] Steam turbine closed-loop water flow path processing flow: water is converted into high-pressure water by the second water pump and enters the first splitter to be divided into the first water flow and the second water flow. The first water flow enters the third heat exchanger to absorb heat from the cathode tail gas of the fuel cell and becomes the first high-temperature and high-pressure steam and enters the first inlet of the second combiner. The second water flow enters the second heat exchanger to absorb heat from the anode tail gas of the fuel cell and becomes the second high-temperature and high-pressure steam and enters the second inlet of the second combiner. The first high-temperature and high-pressure steam and the second high-temperature and high-pressure steam are combined through the second combiner and enter the steam turbine to drive the steam turbine to generate power and then become exhaust steam. The exhaust steam enters the condenser to be cooled and becomes low-temperature and low-pressure water flow and enters the second water pump.

[0022] Furthermore, the hydrocarbon fuel is diesel, methanol, methane, ethanol, formic acid or biomass.

[0023] Further, the chemical reaction in the reformer includes:

[0024] Steam reforming reaction of hydrocarbon fuels:

[0025] ,

[0026] Hydrocarbon fuel dry reforming reaction:

[0027] ,

[0028] Reverse water-gas reaction:

[0029] ,

[0030] Methanation reaction:

[0031] ,

[0032] Methanation reaction:

[0033] .

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. After orderly treatment, the anode tail gas of the fuel cell stack flows back to the inlet of the fuel cell stack to form a closed cycle, so that the system can greatly improve the fuel utilization rate of the solid oxide fuel cell.

[0036] 2. The tail gas of the power stack is used as the heat source of the steam closed cycle. In the steam closed cycle, water is heated by the tail gas of the power stack to become water vapor, which is then used by the steam turbine to generate electricity. This system combines steam combined cycle power generation, which greatly improves the power generation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a structural block diagram of a solid oxide fuel cell double closed combined cycle power generation system provided in Example 1 of the present invention;

[0038] Figure 2 This is a structural block diagram of a solid oxide fuel cell double closed combined cycle power generation system provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention; the terms "first", "second", and "third" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance; in addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be a connection between the two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] Embodiment 1:

[0042] Please refer to Figure 1 , shows a solid oxide fuel cell double closed combined cycle power generation system provided in the first embodiment, including a solid oxide fuel cell, a reformer, a steam turbine, a condenser, a water separator, a CO 2 A separator, a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a first flow splitter, a first flow combiner, a second flow combiner, a boosting device, a compressor, a first water pump, and a second water pump.

[0043] The specific connection structure of the system is as follows:

[0044] The outlet of the first water pump is connected to the low-temperature fluid inlet of the first heat exchanger, the low-temperature fluid outlet of the first heat exchanger is connected to the inlet of the reformer, and the outlet of the reformer is connected to the first inlet of the first combiner.

[0045] The fuel outlet of the booster device is connected to the inlet of the reformer.

[0046] The anode tail gas outlet of the solid oxide fuel cell is connected to the high temperature fluid inlet of the second heat exchanger, the high temperature fluid outlet of the second heat exchanger is connected to the high temperature fluid inlet of the first heat exchanger, the high temperature fluid outlet of the first heat exchanger is connected to the inlet of the water separator, and the anode tail gas outlet of the water separator is connected to the CO 2 Separator inlet; CO 2 The anode tail gas outlet of the separator is connected to the second inlet of the first combiner, and the anode tail gas outlet of the first combiner is connected to the anode inlet of the solid oxide fuel cell.

[0047] The outlet of the compressor is connected to the low-temperature fluid inlet of the fourth heat exchanger, the low-temperature fluid outlet of the fourth heat exchanger is connected to the cathode inlet of the solid oxide fuel cell, the cathode outlet of the solid oxide fuel cell is connected to the high-temperature fluid inlet of the third heat exchanger, the high-temperature fluid outlet of the third heat exchanger is connected to the high-temperature fluid inlet of the fourth heat exchanger, and the high-temperature fluid outlet of the fourth heat exchanger is connected to the external environment.

[0048] The outlet of the second water pump is connected to the inlet of the first splitter, the first outlet of the first splitter is connected to the low-temperature fluid inlet of the third heat exchanger, the low-temperature fluid outlet of the third heat exchanger is connected to the first inlet of the second combiner, the second outlet of the first splitter is connected to the low-temperature fluid inlet of the second heat exchanger, the low-temperature fluid outlet of the second heat exchanger is connected to the second inlet of the second combiner, the outlet of the second combiner is connected to the inlet of the steam turbine, the outlet of the steam turbine is connected to the high-temperature fluid inlet of the condenser, and the high-temperature fluid outlet of the condenser is connected to the inlet of the second water pump.

[0049] The electricity generation outlet of the solid oxide fuel cell is connected to an electricity user, and the heat generation outlet thereof is connected to a heat user and a reformer.

[0050] The heat generating outlet of the water separator is connected to the heat user, and the water outlet is connected to the inlet of the first water pump for recycling, or connected to the water user, or connected to the external environment.

[0051] In practical applications, the water separator can be a condenser, a water silica gel adsorber, a water calcium-based adsorber or an activated alumina adsorber; CO 2 The separator can be a calcium-based adsorber or an amine-based adsorber; the boosting device can select a water pump or a compressor according to the material state of the hydrocarbon fuel.

[0052] This embodiment also provides an operation method of the above-mentioned solid oxide fuel cell double closed combined cycle power generation system, including the following processing flow:

[0053] Air flow processing process: air becomes high-pressure air after passing through the compressor. The high-pressure air enters the fourth heat exchanger and is preheated by the cathode exhaust gas of the fuel cell through the third heat exchanger and then converted into preheated air. The preheated air enters the cathode of the solid oxide fuel cell and participates in the electrochemical reaction to be converted into cathode exhaust gas. After the cathode exhaust gas flows through the third heat exchanger, part of the heat is transferred to the water in the steam turbine cycle, and then flows through the fourth heat exchanger to transfer part of the heat to the air before being discharged into the environment.

[0054] Hydrocarbon fuel flow path processing flow: Hydrocarbon fuel enters the reformer through the booster device to participate in the hydrocarbon fuel reforming reaction. The reformed gas generated by the reforming reaction enters the first combiner and passes through the second heat exchanger, the first heat exchanger, the water separator, the CO 2The anode tail gas of the fuel cell in the separator is combined into the anode fuel gas, and the anode fuel gas enters the anode of the solid oxide fuel cell to participate in the electrochemical reaction.

[0055] Water flow treatment process: Water enters the first heat exchanger through the first water pump, is heated and evaporated to convert into hot water vapor, and the hot water vapor enters the reformer to participate in the hydrocarbon fuel reforming reaction.

[0056] Fuel cell anode tail gas flow path processing process: The anode tail gas discharged from the solid oxide fuel cell enters the second heat exchanger, releases heat and turns into the second anode tail gas, enters the first heat exchanger, releases heat and turns into the third anode tail gas, and then enters the water separator, removes the electrochemical reaction product water and turns into the fourth anode tail gas, and enters the CO 2 Separator, to separate the electrochemical product CO 2 It is then converted into the fifth anode tail gas and enters the first combiner, where it is combined with the reformed gas to form the anode fuel gas and flows back to the anode inlet of the solid oxide fuel cell.

[0057] Steam turbine closed-loop water flow path processing flow: water is converted into high-pressure water by the second water pump and enters the first splitter to be divided into the first water flow and the second water flow. The first water flow enters the third heat exchanger to absorb heat from the cathode tail gas of the fuel cell and becomes the first high-temperature and high-pressure steam and enters the first inlet of the second combiner. The second water flow enters the second heat exchanger to absorb heat from the anode tail gas of the fuel cell and becomes the second high-temperature and high-pressure steam and enters the second inlet of the second combiner. The first high-temperature and high-pressure steam and the second high-temperature and high-pressure steam are combined through the second combiner and enter the steam turbine to drive the steam turbine to generate power and then become exhaust steam. The exhaust steam enters the condenser to be cooled and becomes low-temperature and low-pressure water flow and enters the second water pump.

[0058] In the above-mentioned treatment process, the hydrocarbon fuel used is diesel, methanol, methane, ethanol, formic acid or biomass.

[0059] The chemical reactions in the reformer include:

[0060] Steam reforming reaction of hydrocarbon fuels:

[0061] ,

[0062] Hydrocarbon fuel dry reforming reaction:

[0063] ,

[0064] Reverse water-gas reaction:

[0065] ,

[0066] Methanation reaction:

[0067] ,

[0068] Methanation reaction:

[0069] .

[0070] The system and operation method provided in this embodiment process the anode tail gas of the stack in an orderly manner and then flows back to the inlet of the stack to form a closed cycle, so that the system can greatly improve the fuel utilization rate of the solid oxide fuel cell. Furthermore, the tail gas of the stack is used as a heat source for the steam closed cycle. In the steam closed cycle, water is heated by the tail gas of the stack to become water vapor, and then generates electricity through the steam turbine. Since it is combined with steam combined cycle power generation, the power generation efficiency is greatly improved.

[0071] Embodiment 2:

[0072] This embodiment provides another solid oxide fuel cell double closed combined cycle power generation system, which is basically the same as the system in the first embodiment, except that:

[0073] Please refer to Figure 2 The system of this embodiment also includes a second diverter, whose inlet is connected to the anode tail gas outlet of the solid oxide fuel cell, whose first outlet is connected to the inlet of the reformer, and whose second outlet is connected to the high-temperature fluid inlet of the second heat exchanger.

[0074] Compared with Example 1, this embodiment divides the anode exhaust gas output from the solid oxide fuel cell into two paths, one path is supplied to the second heat exchanger, and the other path is returned to the reformer. After the reforming reaction, it flows back to the inlet of the fuel cell stack to form a closed cycle. Compared with Example 1, this system can further improve the fuel utilization rate of the solid oxide fuel cell.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A solid oxide fuel cell double closed combined cycle power generation system, characterized in that: The invention comprises a solid oxide fuel cell, a reformer, a steam turbine, a condenser, a water separator, a CO2 separator, a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a first flow divider, a first flow combiner, a second flow combiner, a pressurizing device, a compressor, a first water pump and a second water pump; The outlet of the first water pump is connected to the low-temperature fluid inlet of the first heat exchanger, the low-temperature fluid outlet of the first heat exchanger is connected to the inlet of the reformer, and the outlet of the reformer is connected to the first inlet of the first combiner; The fuel outlet of the supercharging device is connected to the inlet of the reformer; The anode tail gas outlet of the solid oxide fuel cell is connected to the high-temperature fluid inlet of the second heat exchanger, the high-temperature fluid outlet of the second heat exchanger is connected to the high-temperature fluid inlet of the first heat exchanger, the high-temperature fluid outlet of the first heat exchanger is connected to the inlet of the water separator, and the anode tail gas outlet of the water separator is connected to the inlet of the CO2 separator; the anode tail gas outlet of the CO2 separator is connected to the second inlet of the first combiner, and the anode tail gas outlet of the first combiner is connected to the anode inlet of the solid oxide fuel cell; The outlet of the compressor is connected to the low-temperature fluid inlet of the fourth heat exchanger, the low-temperature fluid outlet of the fourth heat exchanger is connected to the cathode inlet of the solid oxide fuel cell, the cathode outlet of the solid oxide fuel cell is connected to the high-temperature fluid inlet of the third heat exchanger, the high-temperature fluid outlet of the third heat exchanger is connected to the high-temperature fluid inlet of the fourth heat exchanger, and the high-temperature fluid outlet of the fourth heat exchanger is connected to the external environment; The outlet of the second water pump is connected to the inlet of the first splitter, the first outlet of the first splitter is connected to the low-temperature fluid inlet of the third heat exchanger, the low-temperature fluid outlet of the third heat exchanger is connected to the first inlet of the second combiner, the second outlet of the first splitter is connected to the low-temperature fluid inlet of the second heat exchanger, the low-temperature fluid outlet of the second heat exchanger is connected to the second inlet of the second combiner, the outlet of the second combiner is connected to the inlet of the steam turbine, the outlet of the steam turbine is connected to the high-temperature fluid inlet of the condenser, and the high-temperature fluid outlet of the condenser is connected to the inlet of the second water pump; The electricity generation outlet of the solid oxide fuel cell is connected to an electricity user, and the heat generation outlet thereof is connected to a heat user and the reformer; The heat generating outlet of the water separator is connected to a heat user, and the water outlet is connected to the inlet of the first water pump for recycling, or connected to a water user, or connected to the external environment.

2. The solid oxide fuel cell double closed combined cycle power generation system according to claim 1, characterized in that: It also includes a second splitter, whose inlet is connected to the anode tail gas outlet of the solid oxide fuel cell, whose first outlet is connected to the inlet of the reformer, and whose second outlet is connected to the high-temperature fluid inlet of the second heat exchanger.

3. The solid oxide fuel cell double closed combined cycle power generation system according to claim 1, characterized in that: The water separator is a condenser, a water silica gel adsorber, a water calcium-based adsorber or an activated alumina adsorber.

4. The solid oxide fuel cell double closed combined cycle power generation system according to claim 1, characterized in that: The CO2 separator is a calcium-based adsorber or an amine-based adsorber.

5. The solid oxide fuel cell double closed combined cycle power generation system according to claim 1, characterized in that: The pressurizing device adopts a water pump or a compressor according to the material state of the hydrocarbon fuel.

6. An operating method for a solid oxide fuel cell double closed combined cycle power generation system according to any one of claims 1 to 5, characterized in that: The process includes the following: Air flow processing flow: air becomes high-pressure air after passing through the compressor, and the high-pressure air enters the fourth heat exchanger and is preheated by the cathode tail gas of the fuel cell passing through the third heat exchanger and then converted into preheated air, and the preheated air enters the cathode of the solid oxide fuel cell and participates in the electrochemical reaction and is converted into cathode tail gas, and the cathode tail gas passes through the third heat exchanger and transfers part of the heat to the water in the steam turbine cycle, and then passes through the fourth heat exchanger and transfers part of the heat to the air and then is discharged into the environment; Hydrocarbon fuel flow path processing flow: Hydrocarbon fuel enters the reformer through the booster device to participate in the hydrocarbon fuel reforming reaction. The reformed gas generated by the reforming reaction enters the first combiner and merges with the fuel cell anode tail gas that has passed through the second heat exchanger, the first heat exchanger, the water separator, and the CO2 separator to form the anode fuel gas. The anode fuel gas enters the solid oxide fuel cell anode to participate in the electrochemical reaction. Water flow path processing flow: water enters the first heat exchanger through the first water pump, is heated and evaporated to convert into hot water vapor, and the hot water vapor enters the reformer to participate in the hydrocarbon fuel reforming reaction; Fuel cell anode tail gas flow path processing process: the anode tail gas discharged from the solid oxide fuel cell enters the second heat exchanger, releases heat and turns into the second anode tail gas, enters the first heat exchanger, releases heat and turns into the third anode tail gas, and then enters the water separator, removes the electrochemical reaction product water and turns into the fourth anode tail gas, enters the CO2 separator, separates the electrochemical product CO2 and turns into the fifth anode tail gas, enters the first combiner, and merges with the reformed gas to form the anode fuel gas and flows back to the anode inlet of the solid oxide fuel cell; Steam turbine closed-loop water flow path processing flow: water is converted into high-pressure water by the second water pump and enters the first splitter to be divided into the first water flow and the second water flow. The first water flow enters the third heat exchanger to absorb heat from the cathode tail gas of the fuel cell and becomes the first high-temperature and high-pressure steam and enters the first inlet of the second combiner. The second water flow enters the second heat exchanger to absorb heat from the anode tail gas of the fuel cell and becomes the second high-temperature and high-pressure steam and enters the second inlet of the second combiner. The first high-temperature and high-pressure steam and the second high-temperature and high-pressure steam are combined through the second combiner and enter the steam turbine to drive the steam turbine to generate power and then become exhaust steam. The exhaust steam enters the condenser to be cooled and becomes low-temperature and low-pressure water flow and enters the second water pump.

7. The operating method of the solid oxide fuel cell double closed combined cycle power generation system according to claim 6, characterized in that: The hydrocarbon fuel is diesel, methanol, methane, ethanol, formic acid or biomass.

8. The operating method of the solid oxide fuel cell double closed combined cycle power generation system according to claim 6, characterized in that: The chemical reactions in the reformer include: Steam reforming reaction of hydrocarbon fuels: ， Hydrocarbon fuel dry reforming reaction: ， Reverse water-gas reaction: ， Methanation reaction: ， Methanation reaction: 。

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