Fuel cell system, fuel cell generator set and regulation and control method of fuel cell generator set

Abstract

The invention discloses a fuel cell system, a fuel cell generator set and a regulation and control method thereof, and relates to the technical field of fuel cells. The fuel cell system comprises an electrochemical reformer, a primary fuel cell module and a secondary fuel cell module, the electrochemical reformer comprises a reforming air electrode, a reforming fuel electrode and a reforming electrolyte arranged between the reforming air electrode and the reforming fuel electrode, and electric energy can be generated after fuel and air are introduced. The electrochemical reforming catalyst is arranged on the reforming fuel electrode, the fuel entering the electrochemical reformer can be reformed, and the fuel partial pressure and the electrode potential can be improved after the fuel reformed by the electrochemical reformer and subjected to electrochemical reaction enters the primary fuel cell module and the secondary fuel cell module. Fuel is consumed in a graded manner through the first-stage fuel cell module and the second-stage fuel cell module, so that the fuel utilization rate and the power generation efficiency are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and particularly to a fuel cell system, a fuel cell power generation set and a control method thereof. Background Art

[0002] A fuel cell is a highly efficient energy conversion device that can directly convert the chemical energy stored in combustible gases into electrical energy. Since it does not require an intermediate conversion from mechanical energy to electrical energy, it has a higher energy conversion efficiency.

[0003] In the prior art, a fuel cell system usually consists of components such as a reformer, an electrostack, a burner, a heat exchanger, an inverter, etc. The reformer converts fuels such as natural gas and alcohols entering the fuel cell system into a mixed gas mainly composed of H 2 , CO, and CO 2 , so that the anode material of the fuel cell system can stably operate in the fuel for a long time and is more conducive to the progress of the electrochemical reaction. The reforming technologies in the reformer generally can be divided into steam reforming (SR) and partial oxidation reforming (CPOX), etc. In a fuel cell system using steam reforming, a reforming water supply system and a steam generator need to be included to provide the steam required for fuel reforming, increasing the complexity of the fuel cell system. When using oxidative reforming, usually the fuel undergoes a partial oxidation reaction with air to complete the reforming. A large amount of heat is released during the partial oxidation reforming process, consuming the energy in the fuel and resulting in too high reforming energy consumption. At the same time, when undergoing a partial oxidation reaction with air, nitrogen in the air will mix into the fuel to dilute the fuel, resulting in a low fuel partial pressure in the fuel electrode of the fuel cell stack, reducing the electrode potential of the battery and the power generation efficiency. Summary of the Invention

[0004] The purpose of the present invention is to provide a fuel cell system, a fuel cell power generation set and a control method thereof to simplify the fuel cell system and achieve the purpose of reducing the energy consumption of the electrochemical reformer, improving the fuel utilization rate and power generation efficiency of the fuel cell system.

[0005] To achieve this purpose, the present invention adopts the following technical solutions:

[0006] A fuel cell system, comprising:

[0007] An electrochemical reformer, including a reforming air electrode, a reforming fuel electrode and a reforming electrolyte disposed between the reforming air electrode and the reforming fuel electrode. The reforming fuel electrode is provided with an electrochemical reforming catalyst. The electrochemical reformer can generate electrical energy through an electrochemical reaction and can reform the fuel introduced into the electrochemical reformer.

[0008] The primary fuel cell module includes at least one primary fuel cell stack, and the primary fuel cell stack includes a first air electrode, a first fuel electrode, and a first electrolyte disposed between the first air electrode and the first fuel electrode;

[0009] The secondary fuel cell module includes at least one secondary fuel cell stack, and the secondary fuel cell stack includes a second air electrode, a second fuel electrode, and a second electrolyte disposed between the second air electrode and the second fuel electrode;

[0010] A fuel supply unit and an air supply unit, the fuel supply unit supplies fuel to the electrochemical reformer or the electrochemical reformer, the primary fuel cell module and the secondary fuel cell module, and the air supply unit supplies air to the electrochemical reformer, the primary fuel cell module and the secondary fuel cell module.

[0011] As an alternative of the fuel cell system, the electrochemical reforming catalyst is a mixture of an electronic conductor, an oxygen ion conductor, and a fuel reforming catalyst, wherein the ratio of the volume of the electronic conductor to the volume of the electrochemical reforming catalyst > 20%, and the ratio of the volume of the oxygen ion conductor to the volume of the electrochemical reforming catalyst > 20%.

[0012] As an alternative of the fuel cell system, the material of the second fuel electrode is an oxide.

[0013] As an alternative of the fuel cell system, the oxide is a component A or a mixture of component A and component B;

[0014] Wherein, the component A includes one or more of cerium oxide doped with rare earth elements and transition metal elements, perovskite titanate doped with alkali metal elements, transition metal elements and rare earth elements, perovskite chromate doped with alkali metal elements, transition metal elements and rare earth elements, perovskite ferrate doped with alkali metal elements, transition metal elements and rare earth elements, perovskite manganate doped with alkali metal elements, transition metal elements and rare earth elements, and perovskite vanadate doped with alkali metal elements, transition metal elements and rare earth elements;

[0015] The component B includes one or more of doped zirconia, doped cerium oxide, and doped lanthanum gallate.

[0016] As an alternative of the fuel cell system, the primary fuel cell module includes one or more primary fuel cell stack groups, each primary fuel cell stack group includes at least one of the primary fuel cell stacks, and the multiple primary fuel cell stack groups are connected in series, parallel or in a hybrid connection;

[0017] The secondary fuel cell module includes one or more secondary stack groups, each of the secondary stack groups includes at least one of the secondary stacks, and the multiple secondary stack groups are connected in series, parallel or in a hybrid connection.

[0018] As an alternative embodiment of the fuel cell system, the fuel cell system includes a burner disposed within the secondary fuel cell module, and the reforming air electrode, the first air electrode, the second air electrode, the second fuel electrode, the fuel supply unit and the air supply unit are all in communication with the burner.

[0019] As an alternative embodiment of the fuel cell system, the high-temperature exhaust gas generated by the combustion of the burner provides heat for at least part of the fuel provided by the fuel supply unit and at least part of the air provided by the air supply unit through a heat exchange unit.

[0020] As an alternative embodiment of the fuel cell system, the heat exchange unit includes a first heat exchanger and a second heat exchanger, and the first heat exchanger can transfer the heat of the high-temperature exhaust gas to at least part of the air provided by the air supply unit;

[0021] The second heat exchanger can transfer the heat of the high-temperature exhaust gas to at least part of the fuel provided by the fuel supply unit.

[0022] As an alternative embodiment of the fuel cell system, the high-temperature exhaust gas after the combustion of the burner is in communication with a waste heat recovery unit.

[0023] As an alternative embodiment of the fuel cell system, the fuel supply unit provides high-temperature fuel and low-temperature fuel, the high-temperature fuel is in communication with the feed port of the reforming fuel electrode, and the low-temperature fuel is controllably distributed to the feed ports of the reforming fuel electrode, the first fuel electrode and the second fuel electrode;

[0024] The air supply unit provides high-temperature air and low-temperature air, and both the high-temperature air and the low-temperature air are controllably distributed to the intake ports of the reforming air electrode, the first air electrode and the second air electrode.

[0025] As an alternative embodiment of the fuel cell system, the air supply unit further includes a mixer group configured to mix the high-temperature air and the low-temperature air entering the intake ports of the reforming air electrode, the first air electrode and / or the second air electrode.

[0026] As an alternative of the fuel cell system, the fuel cell system includes a first burner and a second burner. The first burner is disposed in the primary fuel cell module, and at least part of the high-temperature tail gas after the reaction of the primary fuel cell stack enters the first burner for combustion. The second burner is disposed in the secondary fuel cell module, and at least part of the high-temperature tail gas after the reaction of the secondary fuel cell stack enters the second burner for combustion.

[0027] As an alternative of the fuel cell system, all of the high-temperature tail gas after the reaction of the primary fuel cell module enters the second burner for combustion. For the high-temperature tail gas after the reaction of the secondary fuel cell module, part of it enters the second burner for combustion, and the other part enters the first burner for combustion.

[0028] As an alternative of the fuel cell system, part of the high-temperature tail gas after the reaction of the primary fuel cell module enters the first burner for combustion, and the other part enters the second burner for combustion; all of the high-temperature tail gas after the reaction of the secondary fuel cell module enters the second burner for combustion.

[0029] A fuel cell power generation set, which includes the fuel cell system according to any one of the above solutions.

[0030] A control method for a fuel cell power generation set, which is applied to the fuel cell power generation set as described above. The control method for the fuel cell power generation set includes the following steps:

[0031] When the fuel cell system is started, the air supply unit provides high-temperature air, and the high-temperature air enters the reforming air electrode, the first air electrode, and the second air electrode respectively. According to the temperature of the reformed air tail gas discharged from the reforming air electrode, the electrochemical reformer is controlled to perform a reforming reaction and generate electric energy; when the temperature of the first air tail gas discharged from the first air electrode is higher than the starting temperature of the primary fuel cell stack, the primary fuel cell stack is started, and the fuel utilization rate of the primary fuel cell stack is controlled to be between 60% and 90%; when the temperature of the second air tail gas discharged from the second air electrode is higher than the starting temperature of the secondary fuel cell stack, the secondary fuel cell stack is started, and the fuel utilization rate of the secondary fuel cell stack is controlled to be between 60% and 99%; and / or,

[0032] When the fuel cell system stops running, first reduce the current of the primary fuel cell stack and the secondary fuel cell stack to zero. When the temperature of the first air tail gas discharged from the first air electrode is lower than the first set temperature, the fuel supply unit stops supplying fuel, and then reduce the current of the electrochemical reformer to zero. The first set temperature is less than the starting temperature of the primary fuel cell stack.

[0033] As an alternative solution to the regulation method of the fuel cell power generation set, when the fuel cell system is started, the steps of controlling the electro-chemical reformer to carry out reforming reaction and generate electric energy according to the temperature of the reformed air exhaust gas discharged from the reformed air electrode include:

[0034] When the temperature of the reformed air exhaust gas is higher than a second set temperature, which is lower than the first set temperature, the fuel supply unit supplies fuel to the electro-chemical reformer;

[0035] By gradually increasing the current of the electro-chemical reformer, control the number of oxygen ions in the electro-chemical reformer to be less than 0.5 times the stoichiometric ratio of water and carbon dioxide generated by the complete reaction of fuel and oxygen ions;

[0036] Maintain the ratio of the current of the electro-chemical reformer and the flow rate of the fuel entering the electro-chemical reformer;

[0037] When the temperature of the first air exhaust gas is higher than the first set temperature, control the ratio of oxygen element to carbon element in the fuel entering the electro-chemical reformer and the ratio of oxygen element to carbon element in the fuel entering the first fuel cell stack to be both between 0.2 and 3.5.

[0038] As an alternative solution to the regulation method of the fuel cell power generation set, when the temperature of the reformed air exhaust gas is higher than the second set temperature, the step of the fuel supply unit supplying fuel to the electro-chemical reformer includes:

[0039] When the temperature of the reformed air exhaust gas is higher than the second set temperature, control the high-temperature fuel and low-temperature fuel supplied by the fuel supply unit to be evenly mixed and then the temperature is regulated to be > 200 °C and then supplied into the electro-chemical reformer.

[0040] As an alternative solution to the regulation method of the fuel cell power generation set, after starting the first fuel cell stack, the method of controlling the fuel utilization rate of the first fuel cell stack to be between 60% and 90% includes:

[0041] Under the condition that the temperature of the fuel entering the first fuel cell stack < the set feed temperature and the ratio of oxygen element to carbon element in the fuel entering the electro-chemical reformer and the ratio of oxygen element to carbon element in the fuel entering the first fuel cell stack are both between 0.2 and 3.5, gradually increase the fuel flow rate and the current of the first fuel cell stack.

[0042] As an alternative solution to the regulation method of the fuel cell power generation set, after starting the second fuel cell stack, the method of controlling the fuel utilization rate of the second fuel cell stack to be between 60% and 99% includes:

[0043] Under the condition that the fuel temperature entering the secondary stack < the set feeding temperature, and the ratios of oxygen element to carbon element in the fuel entering the electrochemical reformer and in the fuel entering the primary stack are both between 0.2 and 3.5, gradually increase the fuel flow rate entering the secondary stack and the current of the secondary stack.

[0044] As an alternative solution to the regulation method of the fuel cell power generation set, when the fuel cell system stops operating, after reducing the currents of the primary stack and the secondary stack to zero, when the temperature of the first air tail gas is lower than the first set temperature, the steps for the fuel supply unit to stop supplying fuel and reduce the current of the electrochemical reformer to zero include:

[0045] After reducing the currents of the primary stack and the secondary stack to zero, by adjusting the current of the electrochemical reformer and the flow rate of the fuel entering the electrochemical reformer, control the ratio of oxygen element to carbon element in the fuel entering the electrochemical reformer to be between 1 and 5;

[0046] When the temperature of the first air tail gas is lower than the first set temperature, the fuel supply unit stops supplying fuel and reduces the current of the electrochemical reformer to zero.

[0047] As an alternative solution to the regulation method of the fuel cell power generation set, when the fuel cell system operates in a steady state, increase or decrease the power of the fuel cell system by controlling the fuel flow rate entering the electrochemical reformer, the fuel flow rate entering the primary stack, the fuel flow rate entering the secondary stack, the current of the primary stack, the current of the secondary stack, and the fuel utilization rate of the secondary stack, ensuring that the fuel utilization rate of the primary stack is between 60% and 90%, the fuel utilization rate of the secondary stack is between 60% and 99%, and the volume fraction of the fuel at the outlet of the first fuel electrode of the primary stack > 20%, the volume fraction of the fuel at the outlet of the second fuel electrode of the secondary stack > 1%, and the total fuel utilization rate of the primary stack and the secondary stack > 70%.

[0048] As an alternative solution to the regulation method of the fuel cell power generation set, when increasing the power of the fuel cell system, the control of the fuel flow rate entering the electrochemical reformer, the fuel flow rate entering the primary stack, the fuel flow rate entering the secondary stack, the current of the primary stack, the current of the secondary stack, and the fuel utilization rate of the secondary stack specifically includes:

[0049] Increase the fuel flow rate into the electrochemical reformer and the fuel flow rates provided by the fuel supply unit to the first-stage stack and the second-stage stack, maintain the current of the first-stage stack unchanged, and increase the current of the second-stage stack; or,

[0050] Maintain the fuel flow rate into the first-stage stack and the fuel flow rates provided by the fuel supply unit to the first-stage stack and the second-stage stack unchanged, maintain the current of the first-stage stack, and increase the fuel utilization rate of the second-stage stack; or,

[0051] Increase the fuel flow rate into the electrochemical reformer and the fuel flow rates provided by the fuel supply unit to the first-stage stack and the second-stage stack, and increase the currents of the first-stage stack and the second-stage stack.

[0052] As an alternative solution of the regulation method of the fuel cell power generation set, when reducing the power of the fuel cell system, controlling the fuel flow rate into the electrochemical reformer, the fuel flow rate into the first-stage stack, the fuel flow rate into the second-stage stack, the current of the first-stage stack, the current of the second-stage stack, and the fuel utilization rate of the second-stage stack specifically includes:

[0053] Reduce the fuel flow rate into the electrochemical reformer and the fuel flow rates provided by the fuel supply unit to the first-stage stack and the second-stage stack, maintain the current of the first-stage stack unchanged, and reduce the current of the second-stage stack; or,

[0054] Maintain the fuel flow rate into the first-stage stack and the fuel flow rates provided by the fuel supply unit to the first-stage stack and the second-stage stack unchanged, maintain the current of the first-stage stack, and reduce the fuel utilization rate of the second-stage stack; or,

[0055] Reduce the fuel flow rate into the electrochemical reformer and the fuel flow rates provided by the fuel supply unit to the first-stage stack and the second-stage stack, and reduce the currents of the first-stage stack and the second-stage stack.

[0056] Advantages of the present invention:

[0057] The fuel cell system provided by the present invention includes an electrochemical reformer, a primary fuel cell module, and a secondary fuel cell module. The electrochemical reformer includes a reforming air electrode, a reforming fuel electrode, and a reforming electrolyte disposed between the reforming air electrode and the reforming fuel electrode, which is equivalent to a fuel cell stack and can generate electrical energy after fuel and air are introduced. By providing an electrochemical reforming catalyst on the reforming fuel electrode, the fuel entering the electrochemical reformer can be reformed. Since the electrochemical reformer generates electricity while reforming, part of the energy during the reforming process becomes electrical energy, and the released heat is reduced. At the same time, the reforming electrolyte can prevent nitrogen in the air from mixing into the fuel to dilute the fuel. Therefore, after the fuel reformed by the electrochemical reformer enters the primary fuel cell module and the secondary fuel cell module, the fuel partial pressure and the electrode potential can be increased. By consuming the fuel in stages through the primary fuel cell module and the secondary fuel cell module, the secondary fuel cell module can reuse the first fuel tail gas generated by the primary fuel cell module, further improving the fuel utilization rate and thus the power generation efficiency of the fuel cell system. In this fuel cell system, by providing an electrochemical reformer and two-stage fuel cell modules, the electrochemical reformer can not only reform the fuel entering the primary fuel cell module, but also prevent nitrogen in the air from mixing into the fuel to dilute the fuel during the reforming process, which is more conducive to the progress of the electrochemical reaction; moreover, it can also generate electricity, reduce the heat released by the reforming reaction, increase the electrode potential of the fuel cell system, improve the fuel utilization rate, and thus improve the efficiency of the fuel cell system.

[0058] The fuel cell power generation unit provided by the present invention includes the above-mentioned fuel cell system, which is more conducive to the progress of the electrochemical reaction, improves the fuel utilization rate, and thus improves the power generation efficiency of the fuel cell power generation unit.

[0059] The regulation method of the fuel cell power generation set provided by the present invention is applied to the above fuel cell power generation set. When the fuel cell system starts, the electrochemical reformer, the first fuel cell stack, and the second fuel cell stack are respectively controlled to start according to the temperature of the reformed air tail gas, the temperature of the first air tail gas, and the temperature of the second air tail gas. The electrochemical reformer performs a reforming reaction and generates electric energy. The fuel after being reformed by the electrochemical reformer and undergoing an electrochemical reaction enters the first fuel cell stack. The first fuel cell stack and the second fuel cell stack react to generate electric energy, and the fuel utilization rates of the first fuel cell stack and the second fuel cell stack are effectively controlled, improving the fuel utilization rate and thus the power generation efficiency of the fuel cell power generation set. When the fuel cell system stops operating, first reduce the current of the first fuel cell stack and the second fuel cell stack to zero. At this time, only the electrochemical reformer reacts to generate electric energy. The electrochemical reformer can conduct oxygen ions in the air to the fuel, and the ratio of carbon element to oxygen element in the reformed fuel tail gas generated by the electrochemical reformer will not cause carbon deposition on the surfaces of the first fuel electrode and the second fuel electrode. When the temperature of the first air tail gas is lower than the first set temperature, then stop the fuel supply and reduce the current of the electrochemical reformer to zero to improve the fuel utilization rate of the fuel cell system and thus the power generation efficiency of the fuel cell power generation set. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 FIG. is a schematic diagram of the working principle of the electrochemical reformer, the first fuel cell stack, and the second fuel cell stack in the fuel cell system provided in Embodiment 1 of the present invention;

[0061] Figure 2 FIG. is a schematic diagram of the principle of the first structure of the first fuel cell stack group in the fuel cell system provided in Embodiment 1 of the present invention;

[0062] Figure 3 FIG. is a schematic diagram of the principle of the second structure of the first fuel cell stack group in the fuel cell system provided in Embodiment 1 of the present invention;

[0063] Figure 4 FIG. is a schematic diagram of the working principle of the fuel supply unit, the air supply unit, the electrochemical reformer, the first fuel cell stack, and the second fuel cell stack in one of the fuel cell systems provided in Embodiment 1 of the present invention;

[0064] Figure 5 FIG. is a schematic diagram of the working principle of one of the fuel cell systems provided in Embodiment 1 of the present invention;

[0065] Figure 6 FIG. is a schematic diagram of the working principle of another fuel cell system provided in Embodiment 1 of the present invention Figure 1 ;

[0066] Figure 7 FIG. is a schematic diagram of the working principle of another fuel cell system provided in Embodiment 1 of the present invention Figure 2 .

[0067] In the figure:

[0068] 100, primary fuel cell module; 200, secondary fuel cell module; 300, electrochemical reformer;

[0069] 310, reforming air electrode; 320, reforming fuel electrode; 330, reforming electrolyte;

[0070] 1, primary stack; 2, secondary stack; 3, desulfurization tank; 4, filter; 5, first flow control valve; 6, first flow distributor; 7, second flow control valve; 8, first mixer; 9, second mixer; 10, second flow distributor; 11, burner; 12, fuel source; 13, first flow controller; 14, fan; 15, third flow control valve; 16, first heat exchanger; 17, second heat exchanger; 18, third heat exchanger; 19, waste heat recovery unit; 20, fourth flow control valve; 21, fifth flow control valve; 22, sixth flow control valve; 23, second flow controller; 24, third flow distributor;

[0071] 101, first air electrode; 102, first fuel electrode; 103, first electrolyte; 201, second air electrode; 202, second fuel electrode; 203, second electrolyte. Detailed implementation manners

[0072] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0073] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is 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 thus should not be construed as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0074] Unless otherwise clearly defined or limited, the terms "install", "connect", "link", and "fix" shall be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. It can be the communication inside two components or the interaction relationship between 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.

[0075] Unless otherwise clearly defined or limited, the first feature being "on" or "under" the second feature may include the direct contact between the first feature and the second feature, or may include the situation where the first feature and the second feature are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0076] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and through specific embodiments.

[0077] Embodiment 1:

[0078] As Figures 1 - 7 shown, this embodiment provides a fuel cell system, including an electrochemical reformer 300, a primary fuel cell module 100, a secondary fuel cell module 200, a fuel supply unit, and an air supply unit. The fuel supply unit supplies fuel to the electrochemical reformer 300 or the electrochemical reformer 300, the primary fuel cell module 100, and the secondary fuel cell module 200. The air supply unit supplies air to the electrochemical reformer 300, the primary fuel cell module 100, and the secondary fuel cell module 200. Air and fuel undergo a reforming reaction and an electrochemical reaction in the electrochemical reformer 300. At least part of the reformed fuel tail gas after the electrochemical reformer 300 undergoes the reforming reaction and the electrochemical reaction enters the primary fuel cell module 100. Fuel and air enter the primary fuel cell module 100, and an electrochemical reaction occurs in the primary fuel cell module 100 to generate electric energy. At least part of the first fuel tail gas after the reaction of the primary fuel cell module 100 enters the secondary fuel cell module 200, and an electrochemical reaction occurs in the secondary fuel cell module 200 to generate electric energy.

[0079] The electrochemical reformer 300 includes a reforming air electrode 310, a reforming fuel electrode 320, and a reforming electrolyte 330 disposed between the reforming air electrode 310 and the reforming fuel electrode 320. The reforming fuel electrode 320 is provided with an electrochemical reforming catalyst. The electrochemical reformer 300 can undergo an electrochemical reaction to generate electric energy and can reform the fuel introduced into the electrochemical reformer 300.

[0080] Specifically, the electrochemical reforming catalyst is a mixture of an electronic conductor, an oxygen ion conductor, and a fuel reforming catalyst. Among them, the ratio of the volume of the electronic conductor to the volume of the electrochemical reforming catalyst > 20%, and the ratio of the volume of the oxygen ion conductor to the volume of the electrochemical reforming catalyst > 20%. The electronic conductor and the oxygen ion conductor have electrical conductivity, enabling the electrochemical reformer 300 to undergo an electrochemical reaction. By controlling the volume of the electronic conductor and the oxygen ion conductor, as well as the current or charge transfer number of the electrochemical reformer 300, the proportion of the fuel participating in the electrochemical reaction in the electrochemical reformer 300 is controlled, so that the fuel in the electrochemical reformer 300 can not only undergo an electrochemical reaction to generate electric energy, but also avoid carbon deposition during the reforming reaction, improving the power generation efficiency of the fuel cell system.

[0081] The electrochemical reformer 300 may include multiple reforming units. Each reforming unit includes a reforming air electrode 310, a reforming fuel electrode 320, and a reforming electrolyte 330 disposed between the reforming air electrode 310 and the reforming fuel electrode 320. The multiple reforming units can be connected in series, parallel, or in a hybrid connection.

[0082] The electrochemical reformer 300 is equivalent to a fuel cell stack and can generate electric energy after fuel and air are introduced. By providing an electrochemical reforming catalyst on the reforming fuel electrode 320, the fuel entering the electrochemical reformer 300 can also be reformed. Since the electrochemical reformer 300 generates electricity while reforming, part of the energy during the reforming process becomes electric energy, and the released heat is reduced. At the same time, the reforming electrolyte 330 can prevent nitrogen in the air from mixing into the fuel to dilute the fuel. Therefore, after the fuel reformed by the electrochemical reformer 300 enters the primary fuel cell module 100 and the secondary fuel cell module 200, the fuel partial pressure and the electrode potential can be increased.

[0083] The primary fuel cell module 100 includes at least one primary fuel cell stack 1. The primary fuel cell stack 1 includes a first air electrode 101, a first fuel electrode 102, and a first electrolyte 103 disposed between the first air electrode 101 and the first fuel electrode 102.

[0084] Specifically, the primary fuel cell module 100 includes one or more primary fuel cell stack groups. Each primary fuel cell stack group includes at least one primary fuel cell stack 1. The multiple primary fuel cell stack groups are connected in series, parallel, or in a hybrid connection.

[0085] When a first - stage stack group includes multiple first - stage stacks 1, as Figure 2 shown, the multiple first - stage stacks 1 can be arranged in parallel. As Figure 3 shown, the multiple first - stage stacks 1 can also be arranged in series. Or, the multiple first - stage stacks 1 are arranged in a mixed connection, that is, the multiple first - stage stacks 1 are divided into at least two groups, each group includes at least two first - stage stacks 1, and after at least two first - stage stacks 1 in each group are connected in parallel, they are then connected in series with other groups. Similarly, when the first - stage fuel cell module 100 includes multiple first - stage stack groups, the multiple first - stage stack groups are connected in series, in parallel or in a mixed connection.

[0086] The first - stage stack 1 includes at least one first - stage single - cell battery. The first - stage single - cell battery includes a first air electrode 101, a first fuel electrode 102 and a first electrolyte 103. The first - stage single - cell battery can use the first air electrode 101, the first fuel electrode 102 or the first electrolyte 103 as a support structure, and the thickness of the support structure is relatively large. Of course, a separate support can also be arranged inside the first - stage single - cell battery, and the support is made of metal, oxide or ceramic.

[0087] The second - stage fuel cell module 200 includes at least one second - stage stack 2. The second - stage stack 2 includes a second air electrode 201, a second fuel electrode 202 and a second electrolyte 203 disposed between the second air electrode 201 and the second fuel electrode 202.

[0088] Specifically, the second - stage fuel cell module 200 includes one or more second - stage stack groups. Each second - stage stack group includes at least one second - stage stack 2, and the multiple second - stage stack groups are connected in series, in parallel or in a mixed connection.

[0089] When a second - stage stack group includes multiple second - stage stacks 2, the multiple second - stage stacks 2 can be arranged in parallel. The multiple second - stage stacks 2 can also be arranged in series. Or, the multiple second - stage stacks 2 are arranged in a mixed connection, that is, the multiple second - stage stacks 2 are divided into at least two groups, each group includes at least two second - stage stacks 2, and after at least two second - stage stacks 2 in each group are connected in parallel, they are then connected in series with other groups. Similarly, when the second - stage fuel cell module 200 includes multiple second - stage stack groups, the multiple second - stage stack groups are connected in series, in parallel or in a mixed connection.

[0090] The second - stage stack 2 includes at least one second - stage single - cell battery. The second - stage single - cell battery includes a second air electrode 201, a second fuel electrode 202 and a second electrolyte 203. The second - stage single - cell battery can use the second air electrode 201, the second fuel electrode 202 and the second electrolyte 203 as a support structure, and the thickness of the support structure is relatively large. Of course, a separate support can also be arranged inside the second - stage single - cell battery, and the support is made of metal, oxide or ceramic.

[0091] The reforming electrolyte 330, the first electrolyte 103, and the second electrolyte 203 are all oxygen ion conductor electrolytes. The oxygen ion conductor electrolyte is an oxygen ion conductor (O 2- ),). During operation, oxygen ions are conducted from the air electrode to the fuel electrode to react with the fuel. The ratio of oxygen element to carbon element on the surface of the fuel electrode is higher than that at the inlet of the fuel channel, which can ensure the diffusion partial pressure and diffusion rate of the fuel at the fuel electrode, and improve the fuel utilization rate.

[0092] Furthermore, the material of the second fuel electrode 202 is an oxide. By setting the material of the second fuel electrode 202 as an oxide, since the reforming electrolyte 330, the first electrolyte 103, and the second electrolyte 203 are all oxygen ion conductor electrolytes, a large amount of water vapor will be generated at the fuel electrode after the electrochemical reformer 300, the first stack 1, and the second stack 2 react. Moreover, the reformed fuel tail gas after the reaction of the electrochemical reformer 300 enters the first stack 1, and the first fuel tail gas after the reaction of the first stack 1 enters the second stack 2, resulting in a large amount of water vapor accumulating at the second fuel electrode 202. Water vapor is oxidizing at high temperatures and will oxidize nickel in the fuel electrode to form nickel oxide. The agglomeration of nickel oxide easily leads to the rapid decay of the second fuel electrode 202. By setting the second fuel electrode 202 to be oxidizing, the second fuel electrode 202 can be prevented from being oxidized, the decay of the second fuel electrode 202 can be reduced, and the fuel utilization rate can be further improved.

[0093] Specifically, the oxide is a component A or a mixture of component A and component B; wherein, component A includes cerium oxide doped with rare earth elements and transition metal elements, perovskite titanates doped with alkali metal elements, transition metal elements, and rare earth elements, perovskite chromates doped with alkali metal elements, transition metal elements, and rare earth elements, perovskite ferrites doped with alkali metal elements, transition metal elements, and rare earth elements, perovskite manganates doped with alkali metal elements, transition metal elements, and rare earth elements, perovskite nickelates doped with alkali metal elements, transition metal elements, and rare earth elements, perovskite vanadates doped with alkali metal elements, transition metal elements, and rare earth elements, or one or more of them; component B includes one or more of doped zirconia, doped cerium oxide, and doped lanthanum gallate.

[0094] One of the optional solutions provided by this embodiment is as follows: There is one fuel supply unit and one air supply unit. The primary fuel cell module 100 and the secondary fuel cell module 200 are both connected to the fuel supply unit, and the primary fuel cell module 100 and the secondary fuel cell module 200 are both connected to the air supply unit. The fuel cell system includes a burner 11, and the burner 11 is arranged inside the secondary fuel cell module 200. The reformed air electrode 310, the first air electrode 101, the second air electrode 201, the second fuel electrode 202, the fuel supply unit, and the air supply unit are all communicated with the burner 11. One fuel supply unit and one air supply unit are arranged in the fuel cell system to supply fuel and air to the electrochemical reformer 300, the primary fuel cell module 100, and the secondary fuel cell module 200 respectively. One burner 11 is arranged in the fuel cell system. When the fuel cell is started, the fuel supply unit supplies fuel to the burner 11, and the air discharged after the air supplied by the air supply unit enters the electrochemical reformer 300, the primary fuel cell module 100, and the secondary fuel cell module 200 enters the burner 11 for combustion. The high-temperature exhaust gas after the burner 11 burns provides preheating heat for the entire fuel cell system. During the steady-state operation of the fuel cell system, at least part of the reformed air exhaust gas generated by the electrochemical reformer 300, at least part of the first air exhaust gas generated by the first air electrode 101, the second air exhaust gas generated by the second air electrode 201, and the second fuel exhaust gas generated by the second fuel electrode 202 can all enter the burner 11 for combustion, and the high-temperature exhaust gas after the burner 11 burns continuously provides preheating energy for the fuel and air in the fuel cell system.

[0095] After the burner 11 burns, high-temperature exhaust gas is generated, and the high-temperature exhaust gas provides heat for at least part of the fuel provided by the fuel supply unit and at least part of the air provided by the air supply unit through the heat exchange unit.

[0096] Specifically, the heat exchange unit includes a first heat exchanger 16 and a second heat exchanger 17. The first heat exchanger 16 can transfer the heat of the high-temperature exhaust gas to at least part of the air provided by the air supply unit to form high-temperature air. The second heat exchanger 17 can transfer the heat of the high-temperature exhaust gas to at least part of the fuel provided by the fuel supply unit to form high-temperature fuel. The first heat exchanger 16 is used to transfer the heat in the high-temperature exhaust gas after the reaction of the burner 11 to at least part of the air provided by the air supply unit, so that at least part of the air forms high-temperature air to enter the primary stack 1 and the secondary stack 2 for reaction. The second heat exchanger 17 is used to transfer the heat in the high-temperature exhaust gas after the reaction of the burner 11 to at least part of the fuel provided by the fuel supply unit, so that at least part of the fuel forms high-temperature fuel to enter the primary stack 1 and the secondary stack 2 for reaction.

[0097] Furthermore, the high-temperature exhaust gas after combustion by the burner 11 is communicated with the waste heat recovery unit 19. The waste heat recovery unit 19 recovers the excess heat of the fuel cell system and supplies it to the unit that demands heat externally, avoiding energy waste.

[0098] Specifically, the heat exchange unit further includes a third heat exchanger 18. The third heat exchanger 18 is used to transfer the heat in the entire fuel cell system to the waste heat recovery unit 19, and the waste heat recovery unit 19 recovers the heat. Of course, in other embodiments, a heat exchange component for exchanging heat with the high-temperature exhaust gas may also be provided in the waste heat recovery unit 19, and the high-temperature exhaust gas is discharged after exchanging heat with the heat exchange component.

[0099] Specifically, as Figure 4 and Figure 5 shown, the fuel supply unit includes a fuel source 12. The fuel source 12 is communicated with the burner 11 through a first flow controller 13, and the discharge port of the second fuel electrode 202 is communicated with the burner 11. The fuel source 12 is communicated with the electrochemical reformer 300, the first-level stack 1, the second-level stack 2, and the burner 11 through a third flow distributor 24. A second flow controller 23 is also provided between the third flow distributor 24 and the first-level stack 1 and the second-level stack 2. The second flow controller 23 is used to control the fuel flow rates entering the electrochemical reformer 300, the first-level stack 1, and the second-level stack 2.

[0100] A fourth flow control valve 20 is also provided between the second flow controller 23 and the electrochemical reformer 300. The inlet of the fourth flow control valve 20 is communicated with the second flow controller 23, and the two outlets of the fourth flow control valve 20 are respectively communicated with the inlet of the electrochemical reformer 300 and the inlet of a fifth flow control valve 21. The two outlets of the fifth flow control valve 21 are respectively communicated with the reformed fuel electrode 320 and the inlet of a sixth flow control valve 22. The two outlets of the sixth flow control valve 22 are respectively communicated with the first fuel electrode 102 and the second fuel electrode 202.

[0101] The fuel in the fuel source 12 is desulfurized by the desulfurization tank 3 and then distributed by the third flow distributor 24 to supply the electro-chemical reformer 300, the first fuel cell stack 1, the second fuel cell stack 2 and the burner 11 respectively. The first flow controller 13 is used to control the fuel flow rate into the burner 11, and the second flow controller 23 is used to control the fuel flow rate into the electro-chemical reformer 300, the first fuel cell stack 1 and the second fuel cell stack 2. The fourth flow control valve 20 is used to control the flow rate of the fuel entering the second heat exchanger 17 for heat exchange with the high-temperature tail gas and the flow rate of the low-temperature fuel. The fuel entering the second heat exchanger 17 for heat exchange with the high-temperature tail gas forms high-temperature fuel and enters the electro-chemical reformer 300. The fifth flow control valve 21 is used to control the flow rate of the low-temperature fuel entering the electro-chemical reformer 300, the first fuel cell stack 1 and the second fuel cell stack 2, and the sixth flow control valve 22 is used to control the low-temperature fuel entering the first fuel cell stack 1 and the second fuel cell stack 2. The fuel is desulfurized by the desulfurization tank 3, which can avoid the sulfur in the fuel from undergoing an oxidation reaction to generate sulfur dioxide and then polluting the environment after being discharged into the atmosphere.

[0102] The air supply unit includes a blower 14 and a fourth flow control valve 20. The blower 14 is connected to the first flow distributor 6 and the third flow control valve 15 through the fourth flow control valve 20. The air outlet of the reforming air electrode 310, the air outlet of the first air electrode 101 and the air outlet of the second air electrode 201 are all connected to the burner 11. A filter 4 is also provided in front of the blower 14 to filter the impurities entering the blower 14 and avoid the impurities from entering the fuel cell system and affecting the efficiency of the fuel cell system.

[0103] The high-temperature tail gas generated by the reaction of the fuel and air entering the burner 11 transfers heat to the air supplied to the first fuel cell stack 1 and the second fuel cell stack 2 by the blower 14 through the first heat exchanger 16, heats the air to high-temperature air, and transfers heat to the fuel distributed to the first fuel cell stack 1 and the second fuel cell stack 2 by the fuel source 12 through the second heat exchanger 17, heating the fuel to high-temperature fuel.

[0104] The fuel supply unit supplies high-temperature fuel and low-temperature fuel. The high-temperature fuel is connected to the feed port of the reforming fuel electrode 320, and the low-temperature fuel is controllably distributed to the feed port of the reforming fuel electrode 320, the feed port of the first fuel electrode 102 and the feed port of the second fuel electrode 202.

[0105] Specifically, the low-temperature fuel is respectively connected to the reforming fuel electrode 320 and the second flow control valve 7 through the first flow control valve 5, and the second flow control valve 7 is respectively connected to the feed port of the first fuel electrode 102 and the feed port of the second fuel electrode 202.

[0106] The high-temperature fuel is the part of the fuel provided by the fuel source 12 that has been heat-exchanged with the high-temperature tail gas through the second heat exchanger 17, and the low-temperature fuel is the part of the fuel that has not been heat-exchanged with the high-temperature tail gas through the second heat exchanger 17. After the low-temperature fuel passes through the first flow control valve 5, the first flow control valve 5 divides the low-temperature fuel into two parts. One part of the low-temperature fuel is mixed with the high-temperature fuel and then enters the electrochemical reformer 300, and the other part of the low-temperature fuel is distributed to the first-stage fuel cell stack 1 and the second-stage fuel cell stack 2 through the second flow control valve 7. The reformed fuel tail gas after the reaction in the electrochemical reformer 300 is mixed with a part of the low-temperature fuel diverted by the second flow control valve 7 and then enters the first-stage fuel cell stack 1. The first fuel tail gas after the reaction in the first-stage fuel cell stack 1 and the other part of the low-temperature fuel diverted by the second flow control valve 7 enter the second-stage fuel cell stack 2, and the second fuel tail gas after the reaction in the second-stage fuel cell stack 2 enters the burner 11 for combustion.

[0107] The air supply unit supplies high-temperature air and low-temperature air, and both the high-temperature air and the low-temperature air are controllably distributed to the air inlets of the reforming air electrode 310, the first air electrode 101, and the second air electrode 201.

[0108] The high-temperature air is respectively connected to the reforming air electrode 310 and the second flow distributor 10 through the first flow distributor 6, and the second flow distributor 10 is respectively connected to the first air electrode 101 and the second air electrode 201. The low-temperature air is respectively connected to the reforming air electrode 310 and the second flow distributor 10 through the third flow control valve 15. The high-temperature air is the part of the air provided by the blower 14 that has been heat-exchanged with the high-temperature tail gas through the first heat exchanger 16, and the low-temperature air is the part of the fuel that has not been heat-exchanged with the high-temperature tail gas through the first heat exchanger 16.

[0109] Specifically, the air supply unit further includes a mixer group, and the mixer group is configured to mix the high-temperature air and the low-temperature air entering the air inlets of the reforming air electrode 310, the first air electrode 101, and / or the second air electrode 201. Mixing the high-temperature air and the low-temperature air evenly forms the air temperature required for the reactions of the electrochemical reformer 300, the first-stage fuel cell stack 1, and the second-stage fuel cell stack 2, which is more conducive to the electrochemical reaction to generate electric energy.

[0110] Specifically, the mixer group includes a first mixer 8 and a second mixer 9. Two inlets of the first mixer 8 are respectively connected to an outlet of the first flow distributor 6 and an outlet of the third flow control valve 15, and the outlet of the first mixer 8 is connected to the air inlet of the reforming air electrode 310. Two inlets of the second mixer 9 are respectively connected to another outlet of the first flow distributor 6 and another outlet of the third flow control valve 15, and the outlet of the second mixer 9 is connected to the air inlet of the second flow distributor 10, and the second flow distributor 10 is used to distribute the air entering the first air electrode 101 and the second air electrode 201.

[0111] The high-temperature air is divided into two parts by the first flow distributor 6. One part of the high-temperature air enters the first mixer 8, and the other part of the high-temperature air enters the second mixer 9. The low-temperature air is divided into two parts through the third flow control valve 15. One part of the low-temperature air enters the first mixer 8, mixes evenly with the high-temperature air in the first mixer 8, and then enters the reforming air electrode 310 in the electrochemical reformer 300. The other part of the low-temperature air enters the second mixer 9, mixes evenly with the high-temperature air in the second mixer 9, and then enters the second flow distributor 10. The second flow distributor 10 distributes the evenly mixed air to the first air electrode 101 and the second air electrode 201. After the second air tail gas is discharged, it enters the burner 11.

[0112] In this embodiment, the flow control valve can not only control the flow rate but also distribute the flow rate. When used at low temperatures, the flow control valve can both control the flow rate and distribute the flow rate. However, when used at high temperatures, the quality requirements for the flow control valve are relatively high. Therefore, a flow distributor is used at high temperatures to distribute the flow rate, which reduces the cost.

[0113] Another optional solution provided by this embodiment is as follows: The fuel supply unit includes a first fuel supply unit and a second fuel supply unit. The first fuel supply unit supplies fuel to the primary fuel cell module 100, and the second fuel supply unit supplies fuel to the secondary fuel cell module 200. The air supply unit includes a first air supply unit and a second air supply unit. The first air supply unit supplies air to the primary fuel cell module 100, and the second air supply unit supplies air to the secondary fuel cell module 200. The fuel cell system includes a first burner and a second burner. The first burner is arranged in the primary fuel cell module 100, and at least part of the high-temperature tail gas after the reaction of the primary fuel cell stack 1 enters the first burner for combustion. The second burner is arranged in the secondary fuel cell module 200, and at least part of the high-temperature tail gas after the reaction of the secondary fuel cell stack 2 enters the second burner for combustion.

[0114] For a fuel cell system with a greater demand for power generation, the number of primary fuel cell stacks in the primary fuel cell module 100 is larger. To meet the supply of fuel and air, the first fuel supply unit and the first air supply unit are used to separately supply fuel and air to the primary fuel cell module 100. The second fuel supply unit and a second air supply unit are used to separately supply fuel and air to the secondary fuel cell module 200. A first burner is provided in the primary fuel cell module 100, and at least part of the high-temperature exhaust gas after the reaction of all the primary fuel cell stacks in the primary fuel cell module 100 enters the first burner for combustion. A second burner is provided in the secondary fuel cell module 200, and at least part of the high-temperature exhaust gas after the reaction of all the secondary fuel cell stacks in the secondary fuel cell module 200 enters the second burner for combustion. Of course, components such as heat exchangers are included in both the primary fuel cell module 100 and the secondary fuel cell module 200. The fuel cell system may include more levels of fuel cell modules, and the electrochemical reformer 300 is disposed in front of the primary fuel cell module 100.

[0115] As Figure 6 shown, all of the high-temperature exhaust gas after the reaction of the primary fuel cell module 100 enters the second burner for combustion, and a part of the high-temperature exhaust gas after the reaction of the secondary fuel cell module 200 enters the second burner for combustion to provide thermal balance for the secondary fuel cell module 200; another part enters the first burner for combustion to provide thermal balance for the primary fuel cell module 100.

[0116] As Figure 7 shown, a part of the high-temperature exhaust gas after the reaction of the primary fuel cell module 100 enters the first burner for combustion to provide thermal balance for the primary fuel cell module 100; another part enters the second burner for combustion. The high-temperature exhaust gas after the reaction of the secondary fuel cell module 200 enters the second burner for combustion to provide thermal balance for the secondary fuel cell module 200.

[0117] This embodiment provides a fuel cell power generation unit, including the above fuel cell system. This fuel cell system is more conducive to the progress of the electrochemical reaction, improves the fuel utilization rate, and thus improves the power generation efficiency of the fuel cell power generation unit.

[0118] Embodiment 2:

[0119] This embodiment provides a control method for a fuel cell power generation unit, which is applied to the fuel cell power generation unit provided in Embodiment 1. The control method for the fuel cell power generation unit includes the following steps:

[0120] When the fuel cell system starts up, the air supply unit provides high-temperature air, which enters the reforming air electrode 310, the first air electrode 101, and the second air electrode 201 respectively. The electrochemical reformer 300 is controlled to carry out reforming reaction and generate electric energy according to the temperature of the reformed air tail gas discharged from the reforming air electrode 310; when the temperature of the first air tail gas discharged from the first air electrode 101 is higher than the starting temperature of the first fuel cell stack 1, the first fuel cell stack 1 is started, and the fuel utilization rate of the first fuel cell stack 1 is controlled to be between 60% and 90%. When the temperature of the second air tail gas discharged from the second air electrode 201 is higher than the starting temperature of the second fuel cell stack 2, the second fuel cell stack 2 is started, and the fuel utilization rate of the second fuel cell stack 2 is controlled to be between 60% and 99%.

[0121] Specifically, it includes the following steps:

[0122] First, the high-temperature air is respectively introduced into the reforming air electrode 310, the first air electrode 101, and the second air electrode 201 to heat the electrochemical reformer 300, the first fuel cell stack 1, and the second fuel cell stack 2 respectively.

[0123] When the fuel cell system starts up, the steps of controlling the electrochemical reformer 300 to carry out reforming reaction and generate electric energy according to the temperature of the air tail gas discharged from the air electrode include:

[0124] When the temperature of the reformed air tail gas is higher than the second set temperature, the fuel supply unit supplies fuel to the electrochemical reformer 300. Specifically, the high-temperature fuel and low-temperature fuel supplied by the fuel supply unit are controlled to be mixed evenly and then the temperature is adjusted to >200 °C and then introduced into the electrochemical reformer 300.

[0125] In this embodiment, the second set temperature is 300 °C.

[0126] By gradually increasing the current of the electrochemical reformer 300, the number of oxygen ions in the electrochemical reformer 300 is controlled to be less than 0.5 times the stoichiometric ratio of water and carbon dioxide formed by the complete reaction of fuel and oxygen ions. Specifically, the number of oxygen ions transported by the reforming electrolyte 330 in each reforming unit in the electrochemical reformer 300 is adjusted so that the total number of oxygen ions in the electrochemical reformer 300 is less than 0.5 times the stoichiometric ratio of water and carbon dioxide formed by the complete reaction of fuel and oxygen ions. It should be noted that the calculation of the stoichiometric ratio of water and carbon dioxide formed by the complete reaction of fuel and oxygen ions is already a prior art and will not be elaborated here.

[0127] Maintain the ratio of the current of the electrochemical reformer 300 to the flow rate of the fuel entering the electrochemical reformer 300. When the total number of oxygen ions in the electrochemical reformer 300 is less than 0.5 times the stoichiometric ratio of water and carbon dioxide generated by the complete reaction of the fuel with oxygen ions, maintain the ratio of the current of the electrochemical reformer 300 to the flow rate of the fuel entering the electrochemical reformer 300 (i.e., the ratio of the average fuel flow rate entering each reforming unit in the electrochemical reformer 300 to the current passing through each reforming unit), so as to control the proportion of the fuel entering the electrochemical reformer 300 for the electrochemical reaction and avoid carbon deposition on the reforming fuel electrode 320 during the reforming reaction in the electrochemical reformer 300.

[0128] When the temperature of the first air exhaust gas is higher than the first set temperature, control the ratio of oxygen element to carbon element in the fuel entering the electrochemical reformer 300 and the ratio of oxygen element to carbon element in the fuel entering the first fuel cell stack 1 to be both between 0.2 and 3.5. This ensures that no carbon deposition occurs on the reforming fuel electrode 320 and the first fuel electrode 102, and avoids affecting the fuel utilization rate.

[0129] During the reforming reaction and electrochemical reaction processes of the electrochemical reformer 300, high-temperature air continuously heats the first fuel cell stack 1, and the heat generated after the reaction of the electrochemical reformer 300 is gradually transferred to the first fuel cell stack 1 and the second fuel cell stack 2, and the temperatures of the first air exhaust gas and the second air exhaust gas also gradually increase.

[0130] In this embodiment, the first set temperature is 450 °C. The reformed fuel exhaust gas after the reaction of the electrochemical reformer 300 enters the first fuel cell stack 1. When the temperature of the first air exhaust gas is higher than 450 °C, by increasing the current of the electrochemical reformer 300 and the flow rate of the fuel entering the electrochemical reformer 300, make the ratio of oxygen element to carbon element in the fuel entering the electrochemical reformer 300 and the ratio of oxygen element to carbon element in the fuel entering the first fuel cell stack 1 both between 0.2 and 3.5.

[0131] At this time, the temperatures of the first air exhaust gas and the second air exhaust gas are still gradually increasing. When the temperature of the first air exhaust gas is higher than the starting temperature of the first fuel cell stack 1, the first fuel cell stack 1 starts to carry out an electrochemical reaction and starts to generate electricity.

[0132] Specifically, after starting the first fuel cell stack 1, the methods for controlling the fuel utilization rate of the first fuel cell stack 1 between 60% and 90% include:

[0133] Under the condition that the fuel temperature entering the first-stage fuel cell stack 1 < the set feed temperature, and the ratios of oxygen element to carbon element in the fuel entering the electrochemical reformer 300 and in the fuel entering the first-stage fuel cell stack 1 are both between 0.2 and 3.5, gradually increase the fuel flow rate entering the first-stage fuel cell stack 1 and the current of the first-stage fuel cell stack 1.

[0134] By increasing the fuel flow rate supplemented to the first-stage fuel cell stack 1 by the fuel supply unit, gradually increase the fuel flow rate entering the first-stage fuel cell stack 1 until the fuel cell system operates in a steady state.

[0135] When the temperature of the second air exhaust gas is higher than the start-up temperature of the first-stage fuel cell stack 1, the second-stage fuel cell stack 2 starts an electrochemical reaction and starts generating electricity.

[0136] After starting the second-stage fuel cell stack 2, the methods for controlling the fuel utilization rate of the second-stage fuel cell stack 2 between 60% and 99% include:

[0137] Under the condition that the fuel temperature entering the second-stage fuel cell stack 2 < the set feed temperature, and the ratios of oxygen element to carbon element in the fuel entering the electrochemical reformer 300 and in the fuel entering the first-stage fuel cell stack 1 are both between 0.2 and 3.5, gradually increase the fuel flow rate entering the second-stage fuel cell stack 2 and the current of the second-stage fuel cell stack 2.

[0138] In this embodiment, the set feed temperature is 700°C to 800°C, the start-up temperatures of both the first-stage fuel cell stack 1 and the second-stage fuel cell stack 2 are 500°C. Since the electrochemical reformer 300, the first-stage fuel cell module 100, and the second-stage fuel cell module 200 are arranged in series, the reformed fuel exhaust gas after the reaction of the electrochemical reformer 300 enters the first-stage fuel cell stack 1, and the first fuel exhaust gas after the reaction of the first-stage fuel cell stack 1 then enters the second-stage fuel cell stack 2. During the heat transfer process, there will be heat loss. Therefore, the temperature of the first air exhaust gas of the first-stage fuel cell stack 1 reaches 500°C first, and the temperature of the second air exhaust gas of the second-stage fuel cell stack 2 reaches 500°C later. The adjustment methods for the currents of the electrochemical reformer 300, the first-stage fuel cell stack 1, and the second-stage fuel cell stack 2 are already prior arts and will not be elaborated here.

[0139] When the fuel cell system starts up, control the start-up of the electrochemical reformer 300, the first-stage fuel cell stack 1, and the second-stage fuel cell stack 2 respectively according to the temperature of the reformed air exhaust gas, the temperature of the first air exhaust gas, and the temperature of the second air exhaust gas. The electrochemical reformer 300 performs a reforming reaction and generates electric energy. The fuel after being reformed by the electrochemical reformer 300 and undergoing an electrochemical reaction enters the first-stage fuel cell stack 1. The first-stage fuel cell stack 1 and the second-stage fuel cell stack 2 react to generate electric energy, and effectively control the fuel utilization rates of the first-stage fuel cell stack 1 and the second-stage fuel cell stack 2, improving the fuel utilization rate and further improving the power generation efficiency of the fuel cell power generation unit.

[0140] During the steady-state operation of the fuel cell system, by adjusting the flow rates of the fuel and the high-temperature air entering the electrochemical reformer 300, as well as the current of the electrochemical reformer 300, and controlling the temperature of the fuel entering the electrochemical reformer 300 to be evenly mixed by the high-temperature fuel and the low-temperature fuel to >200 °C, the ratios of oxygen element to carbon element in the fuel entering the electrochemical reformer 300 and in the fuel entering the first fuel cell stack 1 are both between 0.2 and 3.5. The fuel temperatures entering the first fuel cell stack 1 and the second fuel cell stack 2 are both < the set feed temperature, ensuring that the fuel utilization rate of the first fuel cell stack 1 is between 60% and 90%, the fuel utilization rate of the second fuel cell stack 2 is between 60% and 99%, and the volume fraction of the fuel at the outlet of the first fuel electrode 102 of the first fuel cell stack 1 > 20%, the volume fraction of the fuel at the outlet of the second fuel electrode 202 of the second fuel cell stack 2 > 1%, and the total fuel utilization rate of the first fuel cell stack 1 and the second fuel cell stack 2 > 70%.

[0141] Further, by the fuel flow rate entering the electrochemical reformer 300, the fuel flow rate entering the first fuel cell stack 1, the fuel flow rate entering the second fuel cell stack 2, controlling the current of the first fuel cell stack 1, the current of the second fuel cell stack 2, and the fuel utilization rate of the second fuel cell stack 2 to increase or decrease the power of the fuel cell system, ensuring that the fuel utilization rate of the first fuel cell stack 1 is between 60% and 90%, the fuel utilization rate of the second fuel cell stack 2 is between 60% and 99%, and the volume fraction of the fuel at the outlet of the first fuel electrode 102 of the first fuel cell stack 1 > 20%, the volume fraction of the fuel at the outlet of the second fuel electrode 202 of the second fuel cell stack 2 > 1%, and the total fuel utilization rate of the first fuel cell stack 1 and the second fuel cell stack 2 > 70%.

[0142] Specifically, when increasing the power of the fuel cell system, controlling the fuel flow rate entering the electrochemical reformer 300, the fuel flow rate entering the first fuel cell stack 1, the fuel flow rate entering the second fuel cell stack 2, the current of the first fuel cell stack 1, the current of the second fuel cell stack 2, and the fuel utilization rate of the second fuel cell stack 2 specifically includes:

[0143] Increasing the fuel flow rate entering the electrochemical reformer 300, the fuel flow rates provided by the fuel supply unit for the first fuel cell stack 1 and the second fuel cell stack 2, maintaining the current of the first fuel cell stack 1 unchanged, and increasing the current of the second fuel cell stack 2; or,

[0144] Maintaining the fuel flow rate entering the first fuel cell stack 1, the fuel flow rates provided by the fuel supply unit for the first fuel cell stack 1 and the second fuel cell stack 2 unchanged, maintaining the current of the first fuel cell stack 1, and increasing the fuel utilization rate of the second fuel cell stack 2; or,

[0145] Increase the fuel flow rate into the electrochemical reformer 300 and the fuel flow rates provided by the fuel supply unit to the first-stage stack 1 and the second-stage stack 2, and increase the currents of the first-stage stack 1 and the second-stage stack 2.

[0146] Specifically, when reducing the power of the fuel cell system, controlling the fuel flow rate into the electrochemical reformer 300, the fuel flow rate into the first-stage stack 1, the fuel flow rate into the second-stage stack 2, the current of the first-stage stack 1, the current of the second-stage stack 2, and the fuel utilization rate of the second-stage stack 2 specifically includes:

[0147] Reduce the fuel flow rate into the electrochemical reformer 300 and the fuel flow rates provided by the fuel supply unit to the first-stage stack 1 and the second-stage stack 2, keep the current of the first-stage stack 1 unchanged, and reduce the current of the second-stage stack 2; or,

[0148] Keep the fuel flow rate into the first-stage stack 1 and the fuel flow rates provided by the fuel supply unit to the first-stage stack 1 and the second-stage stack 2 unchanged, keep the current of the first-stage stack 1, and reduce the fuel utilization rate of the second-stage stack 2; or,

[0149] Reduce the fuel flow rate into the electrochemical reformer 300 and the fuel flow rates provided by the fuel supply unit to the first-stage stack 1 and the second-stage stack 2, and reduce the currents of the first-stage stack 1 and the second-stage stack 2.

[0150] When the fuel cell system stops operating, first reduce the currents of the first-stage stack 1 and the second-stage stack 2 to zero. When the temperature of the first air exhaust gas is lower than the first set temperature, the fuel supply unit stops supplying fuel, and then reduce the current of the electrochemical reformer 300 to zero. The first set temperature is less than the startup temperature of the first-stage stack 1. Specifically, it includes the following steps:

[0151] After reducing the currents of the first-stage stack 1 and the second-stage stack 2 to zero, by adjusting the current of the electrochemical reformer 300 and the fuel flow rate into the electrochemical reformer 300, control the ratio of oxygen element to carbon element in the fuel entering the electrochemical reformer 300 to be between 1 and 5. Specifically, keep the current of the electrochemical reformer 300 unchanged, reduce the fuel flow rate into the electrochemical reformer 300, and increase the ratio of oxygen element to carbon element in the fuel entering the electrochemical reformer 300 to between 1 and 5. Or, increase the current of the electrochemical reformer 300, keep the fuel flow rate into the electrochemical reformer 300 unchanged, and increase the ratio of oxygen element to carbon element in the fuel entering the electrochemical reformer 300 to between 1 and 5.

[0152] When the fuel cell system stops operating, first reduce the current of the first fuel cell stack 1 and the second fuel cell stack 2 to zero. At this time, only the electrochemical reformer 300 reacts to generate electrical energy. The electrochemical reformer 300 can conduct oxygen ions in the air to the fuel. The ratio of carbon and oxygen elements in the reformed fuel exhaust gas generated by the electrochemical reformer 300 will not cause carbon deposition on the surfaces of the first fuel electrode 102 and the second fuel electrode 202. When the temperature of the first air exhaust gas is lower than the first set temperature, stop the fuel supply and reduce the current of the electrochemical reformer 300 to zero, so as to improve the fuel utilization rate of the fuel cell system and further improve the power generation efficiency of the fuel cell generator set.

[0153] The above content is only the preferred embodiment of the present invention. For those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. The content of this specification should not be construed as a limitation to the present invention.

Claims

1. A fuel cell system, characterized in that: include: An electrochemical reformer (300) comprising a reforming air electrode (310), a reforming fuel electrode (320) and a reforming electrolyte (330) disposed between the reforming air electrode (310) and the reforming fuel electrode (320), wherein the reforming fuel electrode (320) is provided with an electrochemical reforming catalyst, and the electrochemical reformer (300) can generate electric energy by electrochemical reaction and can reform the fuel introduced into the electrochemical reformer (300); A primary fuel cell module (100) comprises at least one primary fuel cell stack (1), wherein the primary fuel cell stack (1) comprises a first air electrode (101), a first fuel electrode (102), and a first electrolyte (103) disposed between the first air electrode (101) and the first fuel electrode (102); A two-stage fuel cell module (200) comprises at least one two-stage fuel cell stack (2), wherein the two-stage fuel cell stack (2) comprises a second air electrode (201), a second fuel electrode (202), and a second electrolyte (203) disposed between the second air electrode (201) and the second fuel electrode (202); A fuel supply unit and an air supply unit, wherein the fuel supply unit provides fuel to the electrochemical reformer (300) or the electrochemical reformer (300), the first-level fuel cell module (100) and the second-level fuel cell module (200), and the air supply unit provides air to the electrochemical reformer (300), the first-level fuel cell module (100) and the second-level fuel cell module (200).

2. The fuel cell system according to claim 1, characterized in that: The electrochemical reforming catalyst is a mixture of an electronic conductor, an oxygen ion conductor and a fuel reforming catalyst, wherein the ratio of the volume of the electronic conductor to the volume of the electrochemical reforming catalyst is greater than 20%, and the ratio of the volume of the oxygen ion conductor to the volume of the electrochemical reforming catalyst is greater than 20%.

3. The fuel cell system according to claim 1, characterized in that: The material of the second fuel electrode (202) is oxide.

4. The fuel cell system according to claim 3, characterized in that: The oxide is component A or a mixture of component A and component B; Wherein, the A component includes one or more of cerium oxide doped with rare earth elements and transition metal elements, perovskite titanates doped with alkali metal elements, transition metal elements and rare earth elements, perovskite chromates doped with alkali metal elements, transition metal elements and rare earth elements, perovskite ferrites doped with alkali metal elements, transition metal elements and rare earth elements, perovskite manganates doped with alkali metal elements, transition metal elements and rare earth elements, perovskite nickelates doped with alkali metal elements, transition metal elements and rare earth elements, and perovskite vanadates doped with alkali metal elements, transition metal elements and rare earth elements; The B component includes one or more of doped zirconium dioxide, doped cerium oxide, and doped lanthanum gallate.

5. The fuel cell system according to claim 1, characterized in that: The primary fuel cell module (100) comprises one or more primary fuel cell stack groups, each of the primary fuel cell stack groups comprises at least one primary fuel cell stack (1), and a plurality of the primary fuel cell stack groups are connected in series, in parallel or in mixed connection; The secondary fuel cell module (200) comprises one or more secondary fuel cell stack groups, each of the secondary fuel cell stack groups comprises at least one secondary fuel cell stack (2), and a plurality of the secondary fuel cell stack groups are connected in series, in parallel or in mixed connection.

6. The fuel cell system according to any one of claims 1 to 5, characterized in that: The fuel cell system comprises a burner (11), wherein the burner (11) is arranged in the two-stage fuel cell module (200), and the reforming air electrode (310), the first air electrode (101), the second air electrode (201), the second fuel electrode (202), the fuel supply unit and the air supply unit are all connected to the burner (11).

7. The fuel cell system according to claim 6, characterized in that: The high-temperature exhaust gas generated by combustion of the burner (11) provides heat to at least part of the fuel provided by the fuel supply unit and at least part of the air provided by the air supply unit through a heat exchange unit.

8. The fuel cell system according to claim 7, characterized in that: The heat exchange unit comprises a first heat exchanger (16) and a second heat exchanger (17), wherein the first heat exchanger (16) is capable of transferring heat of the high-temperature exhaust gas to at least part of the air provided by the air supply unit; The second heat exchanger (17) is capable of transferring the heat of the high-temperature exhaust gas to at least part of the fuel provided by the fuel supply unit.

9. The fuel cell system according to claim 7, characterized in that: The high-temperature tail gas after combustion in the burner (11) is communicated with the waste heat recovery unit (19).

10. The fuel cell system according to any one of claims 1 to 5, characterized in that: The fuel supply unit provides high-temperature fuel and low-temperature fuel, the high-temperature fuel is connected to the feed port of the reforming fuel electrode (320), and the flow rate of the low-temperature fuel is controllably distributed to the feed port of the reforming fuel electrode (320), the feed port of the first fuel electrode (102), and the feed port of the second fuel electrode (202); The air supply unit provides high-temperature air and low-temperature air, and the high-temperature air and the low-temperature air are both controllably distributed to the air inlet of the reforming air electrode (310), the air inlet of the first air electrode (101), and the air inlet of the second air electrode (201).

11. The fuel cell system according to claim 10, characterized in that: The air supply unit further includes a mixer group configured to mix high-temperature air and low-temperature air entering an air inlet of the reforming air electrode (310), an air inlet of the first air electrode (101) and / or an air inlet of the second air electrode (201).

12. The fuel cell system according to any one of claims 1 to 5, characterized in that: The fuel cell system comprises a first burner and a second burner, wherein the first burner is arranged in the first-stage fuel cell module (100), and at least a portion of the high-temperature exhaust gas after the reaction of the first-stage fuel cell stack (1) enters the first burner for combustion, and the second burner is arranged in the second-stage fuel cell module (200), and at least a portion of the high-temperature exhaust gas after the reaction of the second-stage fuel cell stack (2) enters the second burner for combustion.

13. The fuel cell system according to claim 12, characterized in that: All high-temperature exhaust gas after the reaction of the first-stage fuel cell module (100) enters the second burner for combustion, and part of the high-temperature exhaust gas after the reaction of the second-stage fuel cell module (200) enters the second burner for combustion, and the other part enters the first burner for combustion.

14. The fuel cell system according to claim 12, characterized in that: Part of the high-temperature exhaust gas after the reaction of the first-stage fuel cell module (100) enters the first burner for combustion, and the other part enters the second burner for combustion; all of the high-temperature exhaust gas after the reaction of the second-stage fuel cell module (200) enters the second burner for combustion.

15. A fuel cell generator set, characterized in that: Comprising the fuel cell system according to any one of claims 1 to 14.

16. A control method for a fuel cell generator set, characterized in that: Applied to the fuel cell generator set according to claim 15, the control method of the fuel cell generator set comprises the following steps: When the fuel cell system is started, the air supply unit provides high-temperature air, and the high-temperature air enters the reforming air electrode (310), the first air electrode (101) and the second air electrode (201) respectively, and the electrochemical reformer (300) is controlled to perform a reforming reaction and generate electrical energy according to the temperature of the reforming air exhaust gas discharged from the reforming air electrode (310); when the temperature of the first air exhaust gas discharged from the first air electrode (101) is higher than the start-up temperature of the first-stage stack (1), the first-stage stack (1) is started, and the fuel utilization rate of the first-stage stack (1) is controlled to be between 60% and 90%; when the temperature of the second air exhaust gas discharged from the second air electrode (201) is higher than the start-up temperature of the second-stage stack (2), the second-stage stack (2) is started, and the fuel utilization rate of the second-stage stack (2) is controlled to be between 60% and 99%; and / or, When the fuel cell system stops operating, the currents of the primary stack (1) and the secondary stack (2) are first reduced to zero. When the temperature of the first air exhaust gas discharged from the first air electrode (101) is lower than a first set temperature, the fuel supply unit stops supplying fuel and then reduces the current of the electrochemical reformer (300) to zero. The first set temperature is lower than the start-up temperature of the primary stack (1).

17. The control method of a fuel cell generator set according to claim 16, characterized in that: When the fuel cell system is started, the temperature of the reformed air tail gas discharged from the reformed air electrode (310) controls the electrochemical reformer (300) to perform a reforming reaction and generate electrical energy, comprising: When the temperature of the reformed air tail gas is higher than a second set temperature, the fuel supply unit feeds fuel into the electrochemical reformer (300), and the second set temperature is lower than the first set temperature; By gradually increasing the current of the electrochemical reformer (300), the amount of oxygen ions in the electrochemical reformer (300) is controlled to be less than 0.5 times the stoichiometric ratio of water and carbon dioxide generated by complete reaction of fuel and oxygen ions; Maintaining a ratio between the current of the electrochemical reformer (300) and the flow rate of the fuel entering the electrochemical reformer (300); When the temperature of the first air exhaust gas is higher than the first set temperature, the ratio of oxygen to carbon in the fuel entering the electrochemical reformer (300) and the ratio of oxygen to carbon in the fuel entering the first-stage fuel cell stack (1) are controlled to be between 0.2 and 3.

5.

18. The control method of a fuel cell generator set according to claim 17, characterized in that: When the temperature of the reformed air tail gas is higher than a second set temperature, the step of the fuel supply unit introducing fuel into the electrochemical reformer (300) comprises: When the temperature of the reformed air exhaust is higher than the second set temperature, the high-temperature fuel and the low-temperature fuel supplied by the fuel supply unit are controlled to be mixed evenly and then the temperature is adjusted to >200°C before being introduced into the electrochemical reformer (300).

19. The control method of a fuel cell generator set according to claim 16, characterized in that: After starting the primary stack (1), the method for controlling the fuel utilization rate of the primary stack (1) to be between 60% and 90% comprises: Under the conditions that the temperature of the fuel entering the primary stack (1) is less than the set feed temperature, and the ratio of the oxygen element to the carbon element in the fuel entering the electrochemical reformer (300) and the ratio of the oxygen element to the carbon element in the fuel entering the primary stack (1) are both between 0.2 and 3.5, the fuel flow entering the primary stack (1) and the current of the primary stack (1) are gradually increased.

20. The control method of a fuel cell generator set according to claim 16, characterized in that: After starting the secondary fuel cell stack (2), the method for controlling the fuel utilization rate of the secondary fuel cell stack (2) to be between 60% and 99% comprises: Under the conditions that the temperature of the fuel entering the secondary stack (2) is less than the set feed temperature, and the ratio of the oxygen element to the carbon element in the fuel entering the electrochemical reformer (300) and the ratio of the oxygen element to the carbon element in the fuel entering the primary stack (1) are both between 0.2 and 3.5, the fuel flow entering the secondary stack (2) and the current of the secondary stack (2) are gradually increased.

21. The control method of a fuel cell generator set according to claim 16, characterized in that: When the fuel cell system stops operating, after the currents of the primary stack (1) and the secondary stack (2) are reduced to zero, when the temperature of the first air exhaust gas is lower than a first set temperature, the fuel supply unit stops supplying fuel, and the step of reducing the current of the electrochemical reformer (300) to zero comprises: After the currents of the primary stack (1) and the secondary stack (2) are reduced to zero, the ratio of oxygen to carbon in the fuel entering the electrochemical reformer (300) is controlled to be between 1 and 5 by adjusting the current of the electrochemical reformer (300) and the flow rate of the fuel entering the electrochemical reformer (300); When the temperature of the first air exhaust gas is lower than the first set temperature, the fuel supply unit stops supplying fuel and reduces the current of the electrochemical reformer (300) to zero.

22. The control method of a fuel cell generator set according to claim 16, characterized in that: When the fuel cell system is in steady-state operation, the power of the fuel cell system is increased or decreased by controlling the fuel flow rate entering the electrochemical reformer (300), the fuel flow rate entering the primary stack (1), the fuel flow rate entering the secondary stack (2), the current of the primary stack (1), the current of the secondary stack (2) and the fuel utilization rate of the secondary stack (2), so as to ensure that the fuel utilization rate of the primary stack (1) is between 60% and 90%, the fuel utilization rate of the secondary stack (2) is between 60% and 99%, the volume fraction of the fuel at the outlet of the first fuel electrode (102) of the primary stack (1) is greater than 20%, the volume fraction of the fuel at the outlet of the second fuel electrode (202) of the secondary stack (2) is greater than 1%, and the total fuel utilization rate of the primary stack (1) and the secondary stack (2) is greater than 70%.

23. The control method of a fuel cell generator set according to claim 22, characterized in that: When increasing the power of the fuel cell system, a specific method for controlling the fuel flow rate entering the electrochemical reformer (300), the fuel flow rate entering the primary stack (1), the fuel flow rate entering the secondary stack (2), the current of the primary stack (1), the current of the secondary stack (2) and the fuel utilization rate of the secondary stack (2) comprises: Increasing the fuel flow rate entering the electrochemical reformer (300), the fuel flow rate provided by the fuel supply unit to the primary stack (1) and the secondary stack (2), maintaining the current of the primary stack (1) unchanged, and increasing the current of the secondary stack (2); or, Maintaining the flow rate of the fuel entering the primary stack (1) and the flow rate of the fuel provided by the fuel supply unit to the primary stack (1) and the secondary stack (2) unchanged, maintaining the current of the primary stack (1), and increasing the fuel utilization rate of the secondary stack (2); or, The fuel flow rate entering the electrochemical reformer (300) and the fuel flow rate provided by the fuel supply unit to the primary stack (1) and the secondary stack (2) are increased, thereby increasing the current of the primary stack (1) and the secondary stack (2).

24. The control method of a fuel cell generator set according to claim 22, characterized in that: When reducing the power of the fuel cell system, a specific method for controlling the fuel flow rate entering the electrochemical reformer (300), the fuel flow rate entering the primary stack (1), the fuel flow rate entering the secondary stack (2), the current of the primary stack (1), the current of the secondary stack (2) and the fuel utilization rate of the secondary stack (2) comprises: The fuel flow rate entering the electrochemical reformer (300) and the fuel flow rate provided by the fuel supply unit to the primary stack (1) and the secondary stack (2) are reduced, the current of the primary stack (1) is maintained unchanged, and the current of the secondary stack (2) is reduced; or, Maintaining the flow rate of the fuel entering the primary stack (1) and the flow rate of the fuel provided by the fuel supply unit to the primary stack (1) and the secondary stack (2) unchanged, maintaining the current of the primary stack (1), and reducing the fuel utilization rate of the secondary stack (2); or, The fuel flow rate entering the electrochemical reformer (300) and the fuel flow rate provided by the fuel supply unit to the primary stack (1) and the secondary stack (2) are reduced, thereby reducing the current of the primary stack (1) and the secondary stack (2).

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