Solid oxide fuel cell combined heat and power generation system and method

Abstract

The invention provides a solid oxide fuel cell combined heat and power generation system and method. The system comprises a heat supply module and a power generation module. The heat supply module comprises a combustor, a fuel preheater and an air preheater; the power generation module comprises a balance heat exchanger, an anode heat exchanger, a cathode heat exchanger and an electric pile. The air preheater is connected with the balance heat exchanger, the balance heat exchanger is connected with the cathode heat exchanger, the cathode heat exchanger is connected with the cathode of the electric pile, and the cathode is connected with the cathode heat exchanger; the fuel preheater is connected with the balance heat exchanger, the balance heat exchanger is connected with the anode heat exchanger, the anode heat exchanger is connected with the anode of the galvanic pile, and the anode is connected with the anode heat exchanger; the anode heat exchanger is connected with the combustor; the combustor is connected with the air preheater, and the air preheater is connected with the fuel heat exchanger. The invention further provides a method based on the system. The system is efficient and compact in structure, easy to operate, high in comprehensive efficiency and fuel utilization rate and stable in product output.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a solid oxide fuel cell cogeneration system and method. Background Art

[0002] With the transformation of energy structure and the continuous development of new energy technology, in the future, in the energy industry and power drive field, gas fuels rich in CH4, CO, and H2, such as biogas, industrial byproduct hydrogen, and solar hydrogen production, will become the main fuels in energy and power. Solid oxide fuel cells (SOFCs), as the third generation of fuel cells, have the characteristics of high power generation efficiency, strong fuel applicability, and high-quality waste heat that can be reused. They have great application potential in large-scale power generation, distributed power generation, and combined heat and power generation.

[0003] Solid oxide fuel cell cogeneration technology is a production method that combines power generation and heat supply with SOFC technology as the core. It is not limited by the Carnot cycle and its overall efficiency is 2 to 3 times that of traditional thermal power generation. Fuel cell cogeneration systems are widely used and can provide necessary energy such as electricity, heating and steam for industrial production, food processing, large data centers, shopping malls, hospitals and schools, and are an important part of new energy technology.

[0004] Although the application scenarios of fuel cell cogeneration systems are relatively broad, in the actual production process, the demand for electricity, heat and steam at the application end is extremely volatile. For example, food production and processing and hospital disinfection rooms require intermittent use of steam; the load of industrial steam pipelines and the electricity-to-heat demand ratio of domestic buildings will change with the seasons. The demand for electricity increases in summer, while the demand for heating and steam is large in winter, resulting in the existing fixed-mode fuel cell cogeneration system being difficult to adapt to the dynamic steam, electricity and heat demand. Summary of the invention

[0005] In order to solve the above problems, an object of the present invention is to provide a solid oxide fuel cell cogeneration system and method.

[0006] In order to achieve the above object, the present invention provides a solid oxide fuel cell cogeneration system, which includes a heating module and a power generation module;

[0007] Wherein, the heating module includes a burner, a fuel preheater, and an air preheater;

[0008] The power generation module includes a balancing heat exchanger, an anode heat exchanger, a cathode heat exchanger, and a fuel cell stack, wherein the fuel cell stack is provided with an anode and a cathode;

[0009] The reaction air outlet of the air preheater is connected to the reaction air inlet of the balancing heat exchanger, the reaction air outlet of the balancing heat exchanger is connected to the reaction air inlet of the cathode heat exchanger, the reaction air outlet of the cathode heat exchanger is connected to the inlet of the cathode of the fuel cell stack, and the outlet of the cathode is connected to the medium inlet of the cathode heat exchanger;

[0010] The fuel outlet of the fuel preheater is connected to the fuel inlet of the balancing heat exchanger, the fuel outlet of the balancing heat exchanger is connected to the fuel inlet of the anode heat exchanger, the fuel outlet of the anode heat exchanger is connected to the inlet of the anode, the outlet of the anode is connected to the medium inlet of the anode heat exchanger; the medium outlet of the anode heat exchanger is connected to the fuel inlet of the burner;

[0011] The tail gas outlet of the burner is connected to the medium inlet of the air preheater, and the medium outlet of the air preheater is connected to the medium inlet of the fuel heat exchanger.

[0012] In the above system, the fuel preheater is used to preheat the fuel. The fuel preheater may be provided with a fuel inlet, a fuel outlet, a medium inlet and a medium outlet. After the fuel enters the fuel preheater through the combustion inlet of the fuel preheater, it is preheated and heated by a heat supply medium (hereinafter referred to as a heat source), and the heated fuel is discharged from the fuel outlet of the fuel preheater. In some specific embodiments, a fuel pipeline for accommodating the fuel and a medium pipeline for accommodating the heat source are provided inside the fuel preheater, and the fluids in the two pipelines can exchange heat with each other. The inlet and outlet of the fuel pipeline are respectively the fuel inlet and the fuel outlet, and the inlet and outlet of the medium pipeline are respectively the medium inlet and the medium outlet.

[0013] In the above system, the air preheater is used to preheat the cathode intake air, which is also called reaction air and can be a gas such as air. The air preheater can be provided with a reaction air inlet, a reaction air outlet, a medium inlet and a medium outlet. After the cathode intake air enters the air preheater through the reaction air inlet of the air preheater, it is preheated and heated by a heat source, and the heated cathode intake air is discharged from the reaction air outlet of the air preheater. In some specific embodiments, the interior of the air preheater is provided with a reaction air pipeline for accommodating cathode gas and a medium pipeline for accommodating a heat source, and the fluids in the two pipelines can exchange heat with each other. The inlet and outlet of the reaction air pipeline are the reaction air inlet and the reaction air outlet, respectively, and the inlet and outlet of the medium pipeline are the medium inlet and the medium outlet, respectively.

[0014] In the above system, the burner can provide the heat source required by the fuel preheater and the air preheater, and provide heat for the heating and high-temperature stable operation of the system. The burner is provided with a fuel inlet, a combustion-supporting inlet and an exhaust gas outlet. The fuel and the combustion-supporting air burn in the burner to produce a high-temperature combustion exhaust gas, and the combustion exhaust gas can be transported to the fuel preheater and the air preheater as a heat source for preheating the fuel gas and the reaction air. In some specific embodiments, the exhaust gas outlet of the burner, the medium inlet of the air preheater, the medium outlet of the air preheater, the medium inlet of the fuel preheater, and the medium outlet of the fuel preheater can be connected in sequence.

[0015] In the above system, the balanced heat exchanger is used to balance the heat exchange between the preheated fuel and the preheated reaction air, so that the temperature difference between the inlet of the cathode heat exchanger and the inlet of the anode heat exchanger remains stable. The balanced heat exchanger is provided with a fuel inlet, a fuel outlet, a reaction air inlet and a reaction air outlet. The fuel inlet of the balanced heat exchanger is connected to the fuel outlet of the fuel preheater, and the reaction air inlet of the balanced heat exchanger is connected to the reaction air outlet of the air preheater. In some specific embodiments, a fuel pipeline for accommodating fuel and a reaction air pipeline for accommodating cathode-assisting gas are provided inside the balanced heat exchanger, and the fluids in the two pipelines can exchange heat with each other. The inlet and outlet of the fuel pipeline are the fuel inlet and the fuel outlet, respectively, and the inlet and outlet of the reaction air pipeline are the reaction air inlet and the reaction air outlet, respectively.

[0016] In the above system, the anode heat exchanger is used to exchange heat with the fuel that has undergone balanced heat exchange, so that the fuel reaches the operating temperature of the fuel stack. The anode heat exchanger is provided with a fuel inlet, a fuel outlet, a medium inlet and a medium outlet. The fuel inlet of the anode heat exchanger is connected to the fuel outlet of the balanced heat exchanger. In some specific embodiments, the interior of the anode heat exchanger is provided with a fuel pipeline for accommodating fuel and a medium pipeline for accommodating heat sources such as exhaust gas, and the fluids in the two pipelines can exchange heat with each other. The inlet and outlet of the fuel pipeline are respectively the fuel inlet and the fuel outlet, and the inlet and outlet of the medium pipeline are respectively the medium inlet and the medium outlet.

[0017] In the above system, the cathode heat exchanger is used to heat the reaction air that has undergone balanced heat exchange so that the reaction air reaches the operating temperature of the fuel cell stack. The cathode heat exchanger is provided with a reaction air inlet, a reaction air outlet, a medium inlet and a medium outlet. The reaction air inlet of the cathode heat exchanger is connected to the reaction air outlet of the balanced heat exchanger. The cathode heat exchanger is provided with a reaction air pipeline for accommodating cathode gas and a medium pipeline for accommodating heat sources such as exhaust gas, and the fluids in the two pipelines can exchange heat with each other. The inlet and outlet of the reaction air pipeline are respectively the reaction air inlet and the reaction air outlet, and the inlet and outlet of the medium pipeline are respectively the medium inlet and the medium outlet.

[0018] In the above system, the stack is used to make the fuel and the reaction air undergo redox reaction to supply electric energy to the outside. The stack is provided with an anode and a cathode. The fuel loses electrons in the anode to undergo oxidation reaction and produce anode tail gas; the reaction air obtains electrons in the cathode to undergo reduction reaction and produce cathode tail gas.

[0019] In the above system, the anode is provided with an inlet and an outlet, and the inlet of the anode is connected to the fuel outlet of the anode heat exchanger. The cathode is provided with an inlet and an outlet, and the inlet of the cathode is connected to the reaction air outlet of the cathode heat exchanger. In some specific embodiments, an anode conduit may be provided in the anode, and the anode conduit connects the inlet of the anode and the outlet of the anode. A cathode conduit may be provided in the cathode, and the cathode conduit connects the inlet of the cathode and the outlet of the cathode.

[0020] In the above system, the medium outlet of the cathode heat exchanger can also be connected to the medium inlet of the air preheater, and the cathode tail gas is transported to the cathode heat exchanger as a heat source for secondary preheating of the reaction air. The cathode tail gas after heat exchange can be discharged from the medium outlet of the cathode heat exchanger, and provide the heat required for the preheating process to the air preheater and the fuel preheater in turn. That is, the medium outlet of the cathode heat exchanger, the medium inlet of the air preheater, the medium outlet of the air preheater, the medium inlet of the fuel preheater, and the medium outlet of the fuel preheater can be connected in sequence. In some specific embodiments, the medium outlet of the cathode heat exchanger can first be collected in the same pipeline with the tail gas outlet of the burner to mix the cathode tail gas with the combustion tail gas, and then the pipeline is used to connect with the medium inlet of the air preheater and the medium inlet of the fuel preheater.

[0021] In the above system, the outlet of the anode is connected to the medium inlet of the anode heat exchanger, and the outlet of the cathode is connected to the medium inlet of the cathode heat exchanger, and the anode tail gas and the cathode tail gas can be used to provide heat for the heat exchange process in the anode heat exchanger and the cathode heat exchanger respectively. The anode tail gas after heat exchange is discharged from the medium outlet of the anode heat exchanger, and the cathode tail gas after heat exchange is discharged from the medium outlet of the cathode heat exchanger. The above connection relationship can improve the utilization rate of the anode tail gas and the cathode tail gas, and improve the heat utilization rate of the system.

[0022] In the above system, the medium outlet of the anode heat exchanger can also be connected to the fuel inlet of the balancing heat exchanger. That is, the medium outlet of the anode heat exchanger can be connected to the fuel inlet of the burner and the fuel inlet of the balancing heat exchanger respectively. The anode tail gas usually contains unreacted fuel. After the anode tail gas is heat exchanged, it is transported to the burner for combustion, or transported to the anode via the balancing heat exchanger and the anode heat exchanger for electrochemical reaction, which can improve fuel utilization and save energy consumption.

[0023] In the above system, the power generation module may include a first regulating diverter valve and a second regulating diverter valve. The connection relationship between the medium outlet of the anode heat exchanger and the fuel inlet of the burner and the fuel inlet of the balancing heat exchanger can be controlled by the first regulating diverter valve and the second regulating diverter valve. Specifically, the inlet of the first regulating diverter valve can be connected to the medium outlet of the anode heat exchanger, the outlet of the first regulating diverter valve can be connected to the inlet of the second regulating diverter valve and the fuel inlet of the balancing heat exchanger, and the outlet of the second regulating diverter valve can be connected to the fuel inlet of the burner. The first regulating diverter valve can adjust the amount of anode tail gas entering the second regulating diverter valve in the anode tail gas discharged from the anode heat exchanger, and the second regulating diverter valve can adjust the amount of anode tail gas entering the burner.

[0024] In the above system, the first regulating diverter valve may have one inlet and at least two outlets. Figure 3 As shown, the outlet of the first regulating diverter valve can be connected to the inlet of the second regulating diverter valve and the inlet of the balancing heat exchanger respectively. Further, the outlet of the first regulating diverter valve can be connected to the inlet of the second regulating diverter valve and the inlet of the balancing heat exchanger at the same time, so as to adjust the ratio of the anode tail gas entering the second regulating diverter valve and the anode tail gas entering the balancing heat exchanger. The opening of the first regulating diverter valve is adjustable, and can be specifically a three-way valve.

[0025] In the above system, the power generation module may further include a heat box, which is used to stabilize the temperature of the stack. In some specific embodiments, the stack is located in the heat box to maintain a uniform temperature and heat distribution of the stack core.

[0026] In the power generation module of the above system, the balancing heat exchanger, the anode heat exchanger and the cathode heat exchanger form a two-stage balancing heat exchange system. The preheated fuel gas and reaction air are subjected to a heat exchange (i.e., balancing heat exchange) in the balancing heat exchanger, and then to a heat exchange in the anode heat exchanger and the cathode heat exchanger. The balancing heat exchanger, the anode heat exchanger, the cathode heat exchanger and the heat box can keep the temperature difference between the anode inlet and the cathode inlet of the stack, the temperature difference between the anode outlet and the cathode outlet, and the temperature of the stack stable, so that the stack is heated evenly during operation.

[0027] According to a specific embodiment of the present invention, the above-mentioned system may further include a waste heat collection module, the inlet of which may be connected to the exhaust gas outlet of the burner and / or the medium outlet of the cathode heat exchanger, and the connection between the exhaust gas outlet of the burner and / or the cathode heat exchanger and the waste heat collection module may be direct or indirectly connected through equipment such as an air preheater and / or a fuel heat exchanger, thereby collecting and utilizing the heat of the combustion exhaust gas and / or cathode exhaust gas to generate heat externally.

[0028] In some specific embodiments, when both the burner and the cathode heat exchanger are connected to the waste heat collection module, the exhaust gas outlet of the burner and the medium outlet of the cathode heat exchanger can be respectively connected to the inlet of the waste heat collection module, or the exhaust gas outlet of the burner and the medium outlet of the cathode heat exchanger can be combined in the same pipeline to mix the combustion exhaust gas and the cathode exhaust gas, and then the pipeline is connected to the inlet of the waste heat collection module.

[0029] Furthermore, the burner and / or cathode heat exchanger may be connected to the air preheater, the fuel heat exchanger, and the waste heat collection module in sequence. Specifically, the tail gas outlet of the burner and / or the medium outlet of the cathode heat exchanger, the medium inlet of the air preheater, the medium outlet of the air preheater, the medium inlet of the fuel heat exchanger, the medium outlet of the fuel heat exchanger, and the inlet of the waste heat collection module may be connected in sequence. Furthermore, the tail gas outlet of the burner and the medium outlet of the cathode heat exchanger may be combined in the same pipeline, which is then connected to the medium inlet of the air preheater, the medium outlet of the air preheater, the medium inlet of the fuel heat exchanger, the medium outlet of the fuel heat exchanger, and the inlet of the waste heat collection module in sequence.

[0030] In some specific embodiments, the waste heat collection module includes a water heater. The water heater can use the waste heat in the system (heat of combustion tail gas and / or cathode tail gas) to produce hot water. The water heater can be provided with a medium inlet, a medium outlet, a water inlet, and a water outlet. The medium inlet of the water heater is directly connected to the tail gas outlet of the burner and / or the medium outlet of the cathode heat exchanger, or the medium inlet of the water heater is directly connected to the medium outlet of the air preheater and / or the medium outlet of the fuel heat exchanger.

[0031] According to a specific embodiment of the present invention, the above system may further include a steam generation module. The steam generation module is provided with a fuel inlet, which is connected to the medium outlet of the anode heat exchanger, and produces steam using the heat carried by the anode tail gas discharged from the anode heat exchanger. When the above system includes a first regulating diverter valve, the medium outlet of the anode heat exchanger is generally connected to the inlet of the first regulating valve, and the outlet of the first regulating valve is optionally connected to the fuel inlet of the balancing heat exchanger and the inlet of the second regulating valve.

[0032] According to a specific embodiment of the present invention, when the power generation module includes a second regulating valve, the fuel inlet of the steam generation module and the fuel inlet of the burner are respectively connected to the outlet of the second regulating diverter valve. The amount of anode tail gas entering the burner and entering the steam generation module can be adjusted by using the second regulating diverter valve. The opening of the first regulating diverter valve and the second regulating diverter valve is adjustable, and can be specifically a three-way valve.

[0033] According to a specific embodiment of the present invention, the first regulating diverter valve and the second regulating diverter valve each have at least two outlets, the inlet of the first regulating diverter valve is connected to the medium outlet of the anode heat exchanger, and the outlet of the first regulating diverter valve is respectively connected to the inlet of the second regulating diverter valve and the fuel inlet of the balancing heat exchanger; the outlet of the second regulating diverter valve is respectively connected to the fuel inlet of the burner and the fuel inlet of the steam generating module.

[0034] In some specific embodiments, the steam generation module may include a steam boiler, which may include a combustion chamber and a steam generation chamber. The combustion chamber is used to perform a combustion reaction and provide heat generated by the combustion to the steam generation chamber, and the inlet of the combustion chamber is connected to the outlet of the second regulating diverter valve as the inlet of the steam generation module.

[0035] In the steam generation module, the steam generation chamber is used to convert water into steam. In some specific embodiments, the steam generation chamber can produce superheated steam. The steam generation chamber can specifically include a saturated steam generation section and a steam superheating section, wherein the saturated steam generation section converts water into saturated steam, and the steam superheating section converts saturated steam into superheated steam.

[0036] In some specific embodiments, the saturated steam generating section may be provided with a first steam pipe and a first flue gas pipe, and heat exchange may be performed between the first steam pipe and the first flue gas pipe; the steam superheating section may be provided with a second steam pipe and a second flue gas pipe, and heat exchange may be performed between the second steam pipe and the second flue gas pipe. The combustion chamber, the first flue gas pipe and the second flue gas pipe are connected in sequence to transmit the flue gas generated by combustion; the first steam pipe and the second steam pipe are connected to transmit steam.

[0037] In some specific embodiments, the combustion chamber, the saturated steam generating section and the steam superheating section may be connected in sequence from bottom to top.

[0038] In some specific embodiments, the inlet to outlet direction of the first steam pipe may be opposite to the inlet to outlet direction of the second steam pipe. For example, the inlet of the first steam pipe may be located at the bottom of the saturated steam generating section, and the outlet of the first steam pipe may be located at the top of the saturated steam generating section; the inlet of the second steam pipe may be located at the top of the steam superheating section, and the outlet of the second steam pipe may be located at the bottom of the saturated steam generating section.

[0039] Further, the inlet-to-outlet direction of the first flue gas duct and the inlet-to-outlet direction of the second flue gas duct may be the same as the inlet-to-outlet direction of the first steam duct. For example, the inlet of the first flue gas duct may be located at the bottom of the saturated steam generating section, and the outlet of the first flue gas duct may be located at the top of the saturated steam generating section. The inlet of the second flue gas duct may be located at the bottom of the steam superheating section, and the outlet of the second flue gas duct may be located at the top of the steam superheating section.

[0040] In the saturated steam generation section, water is stored in the first steam pipe, and the flue gas in the first flue gas pipe transfers heat to the water, causing the water to evaporate and form saturated steam. The saturated steam moves upward in the first steam pipe, enters the second steam pipe and moves downward, fully exchanging heat with the flue gas that continues to move upward along the second flue gas pipe, so that the saturated steam is converted into superheated steam.

[0041] In the above steam generation module, the steam generation module may further include a fan, and the fan is used to provide combustion-supporting gas, such as combustion-supporting air, to the combustion chamber.

[0042] In some specific embodiments, the steam generation module may include more than two fans, each of which is connected to the combustion chamber via a bypass pipe. By switching the bypass pipe, each fan can be switched to meet the larger combustion-supporting gas demand of the combustion chamber and ensure stable operation of the system.

[0043] In the above system, the steam generation module and the waste heat collection module are used to produce high-quality steam and hot water respectively, both of which require high-temperature heat sources. By setting the steam generation module and the waste heat collection module as independent modules, the mutual interference between the steam output and the system preheating process can be avoided, which helps to improve the quality of the system's steam products and enhance the system's rapid response to changes in the volatility of steam demand.

[0044] The present invention also provides a solid oxide fuel cell cogeneration method, which is carried out in the above solid oxide fuel cell cogeneration system, and comprises:

[0045] The fuel gas enters the fuel preheater for preheating, the reaction air enters the air preheater for preheating, and the preheated fuel gas and reaction air enter the balance heat exchanger for balance heat exchange;

[0046] The reaction air after balanced heat exchange is heated in the cathode heat exchanger, and the heated reaction air enters the cathode to undergo reduction reaction to produce cathode tail gas, and the cathode tail gas discharged from the cathode enters the cathode heat exchanger to exchange heat with the reaction air;

[0047] The fuel gas after balanced heat exchange is heated in the anode heat exchanger, and the heated fuel gas enters the anode to undergo oxidation reaction to generate anode tail gas; the anode tail gas discharged from the anode is transported to the anode heat exchanger to exchange heat with the fuel gas, and the anode tail gas after heat exchange enters the burner, and the anode tail gas is burned with the combustion-supporting air in the burner to generate heat to generate combustion tail gas, which is discharged from the burner;

[0048] The combustion exhaust gas discharged from the burner is transported to the air preheater and the fuel preheater as a heat source, providing a heat source for preheating the fuel and the reaction air.

[0049] According to a specific embodiment of the present invention, the above method can control all anode tail gas in the anode heat exchanger to enter the burner and burn with combustion air (usually excess combustion air), thereby accelerating the system temperature rise.

[0050] According to a specific embodiment of the present invention, the intake ratio of the combustion air to the anode tail gas in the burner can be 3-6 to accelerate the heat generation of the burner, maintain the thermal balance of the power generation module and the stable operation of the system.

[0051] According to a specific embodiment of the present invention, when the medium outlet of the cathode heat exchanger is also connected to the medium inlet of the air preheater, the above method also includes: transporting the combustion exhaust gas discharged from the cathode exhaust gas burner discharged from the cathode heat exchanger to the air preheater and the fuel preheater as a heat source, providing a heat source for preheating of the fuel and preheating of the reaction air.

[0052] According to a specific embodiment of the present invention, when the system further includes a waste heat collection module, the method may further include: conveying the combustion tail gas discharged from the burner to the waste heat collection module as a heat source. Further, the above method may further include: conveying the cathode tail gas after heat exchange in the cathode heat exchanger to the air preheater, the fuel preheater, and the waste heat collection module as a heat source.

[0053] In some specific embodiments, when the waste heat collection module includes a water heater, the heat production efficiency is the efficiency of producing hot water. By adjusting the flow rate of water to be heated in the water heater, the temperature of the hot water product and the waste heat utilization efficiency can be controlled.

[0054] According to a specific embodiment of the present invention, the method may further include: delivering the cathode tail gas discharged from the cathode and the combustion tail gas discharged from the burner to at least one of an air preheater, a fuel preheater, and a waste heat collection module as a heat source. Further, the cathode tail gas discharged from the cathode and the combustion tail gas discharged from the burner may be delivered to the air preheater, the fuel preheater, and the waste heat collection module in sequence as a heat source.

[0055] When the medium outlet of the anode heat exchanger is only connected to the fuel inlet of the burner, but not to the fuel inlet of the balancing heat exchanger and the fuel inlet of the steam generation module, the corresponding method uses the battery stack to output electricity through an external circuit (i.e., supply power to the outside) and uses the waste heat collection module to supply heat to the outside in the form of hot water, and the heat production efficiency is higher than the power generation efficiency, which can be called the cogeneration mode of the method. In some specific embodiments, in the method in the cogeneration mode, the ratio of the hot water output efficiency to the power generation efficiency can reach 0.8-2.1.

[0056] According to a specific embodiment of the present invention, when the medium outlet of the anode heat exchanger is connected to the fuel inlet of the burner and the fuel inlet of the balancing heat exchanger respectively, the method may further include: transporting the anode tail gas discharged from the anode heat exchanger to the fuel inlet of the burner and the fuel inlet of the balancing heat exchanger respectively, the anode tail gas undergoes balanced heat exchange in the balancing heat exchanger, and the anode tail gas undergoing balanced heat exchange enters the anode after heat exchange through the anode heat exchanger. Since the medium outlet of the anode heat exchanger is simultaneously connected to the inlet of the burner and the fuel inlet of the balancing heat exchanger, the anode tail gas discharged from the anode heat exchanger can be mixed with the preheated fresh (unreacted) fuel delivered by the fuel preheater, and enter the balancing heat exchanger together for balanced heat exchange and then enter the stack to participate in the anode reaction. Specifically, the anode tail gas is discharged from the anode and enters the anode heat exchanger as a heat source; the anode tail gas after heat exchange is discharged from the anode heat exchanger, mixed with the fresh fuel gas from the fuel preheater, and then enters the balancing heat exchanger as a substance to be heat exchanged, and then enters the anode heat exchanger as a substance to be heat exchanged after heat balance, and then enters the anode to participate in the oxidation reaction after heat exchange. The above process can be called anode tail gas circulation. The anode tail gas usually contains about 30% fuel and the rest is water vapor. The above-mentioned anode circulation process can use the residual fuel in the anode tail gas to provide raw materials for the stack, and further convert the unreacted fuel into electrical energy, thereby improving the fuel utilization rate and the anode reaction efficiency, and further significantly improving the power generation efficiency of the power generation mode. The above method uses the stack to supply power to the outside, and uses the waste heat collection module to supply heat to the outside, and includes an anode tail gas circulation process, so that the anode tail gas and the fuel gas are used as fuel for the anode, and the power generation efficiency is higher than the output hot water efficiency, which can be called the power generation mode of the method. In some specific embodiments, in the method in the power generation mode, the ratio of the output hot water efficiency to the power generation efficiency can be 0.4-0.95.

[0057] According to a specific embodiment of the present invention, when the system also includes a steam generation module, and the medium outlet of the anode heat exchanger is respectively connected to the fuel inlet of the burner and the fuel inlet of the steam generation module, the method may further include: transporting the anode tail gas discharged from the anode heat exchanger to the fuel inlet of the burner and the steam generation module respectively, the anode tail gas is burned in the steam generation module to generate heat, so that the water in the steam generation module is heated and evaporated to produce superheated steam. This method uses the battery stack to supply power to the outside, uses the waste heat collection module to supply heat to the outside, and uses the steam generation module to produce superheated steam at the same time, which can be called the cogeneration mode of the method. In some specific embodiments, in the method in the cogeneration mode, the ratio of steam output efficiency to power generation efficiency can reach 0.6-1.8.

[0058] According to a specific embodiment of the present invention, when the medium outlet of the anode heat exchanger is respectively connected to the fuel inlet of the burner and the fuel inlet of the steam generating module, the above method is in a cogeneration mode, and the volume of the anode tail gas discharged from the anode heat exchanger is 100%, the volume of the anode tail gas entering the burner from the anode heat exchanger is less than 10%, and the volume of the anode tail gas entering the steam generating module from the anode heat exchanger is more than 90%.

[0059] According to a specific embodiment of the present invention, the superheated steam production process may include: the anode tail gas burns with combustion-supporting air in a combustion chamber to produce flue gas, the flue gas is transmitted to a saturated steam generating section and a steam superheating section in sequence, the flue gas exchanges heat with water in the saturated steam generating section, the water is heated and evaporated to be converted into steam, the steam enters the steam superheating section to exchange heat with the flue gas, and the steam is heated and converted into superheated steam.

[0060] According to a specific embodiment of the present invention, the temperature of the superheated steam is 160° C. to 250° C., and the pressure of the superheated steam is 0.6 MPa to 1.0 MPa.

[0061] In some specific embodiments, at least one of the reaction air introduced into the cathode of the fuel cell stack, the combustion air introduced into the burner, and the combustion air delivered by the fan includes air and / or oxygen.

[0062] In a specific embodiment of the present invention, the above method can be flexibly switched to power generation mode, cogeneration mode and steam-power cogeneration mode, and the switching between the above modes is achieved by controlling the connection relationship between the medium outlet of the anode heat exchanger and the burner, the balancing heat exchanger and the steam generation module, that is, controlling the diversion of the anode tail gas. During the operation of the existing fuel cell system, the diversion of the anode tail gas will cause the temperature of the anode side of the stack to fluctuate. The present invention can ensure the stability of the anode side temperature by setting a balancing heat exchanger and utilizing the heat transfer between the reaction air and the fuel and the anode tail gas, thereby maintaining the normal and stable operation of the stack during the system's variable operating conditions.

[0063] It can be understood that when the above-mentioned solid oxide fuel cell cogeneration system is in the startup stage, all the fuel in the system can enter the burner to burn and generate heat, and the generated heat enters the fuel preheater and air preheater as a heat source; at this time, the combustion outlet of the anode heat exchanger can be directly connected to the fuel inlet of the burner.

[0064] The beneficial effects of the present invention are:

[0065] 1. The temperature difference between the inlet and outlet of the stack in the solid oxide fuel cell cogeneration system provided by the present invention is stable, the stack is heated evenly during operation, and can operate stably for a long period of time.

[0066] 2. The system provided by the present invention has a compact structure and is easy to operate. The system has an overall efficiency of more than 80% during operation, a high fuel utilization rate, and can provide power and heat to the outside.

[0067] 3. Further optimization of the above system can improve the flexibility of the above system, so that the system has three operating modes: power generation, cogeneration, and cogeneration, which is suitable for scenarios with strong fluctuations and large demand for steam, heat, and electricity. The system can produce high-quality superheated steam of 160-250℃ and 0.6-1.0MPa when operating in cogeneration mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 This is a schematic structural diagram of the solid oxide fuel cell cogeneration system of Example 1.

[0069] Figure 2 This is a schematic diagram of the solid oxide fuel cell cogeneration method of Example 2.

[0070] Figure 3 This is a schematic diagram of the solid oxide fuel cell cogeneration method of Example 3.

[0071] Figure 4 This is a schematic diagram of the solid oxide fuel cell cogeneration method of Example 4.

[0072] Explanation of symbols

[0073] 1. Fuel preheater; 2. Air preheater; 3. Balance heat exchanger; 4. Anode heat exchanger; 5. Cathode heat exchanger; 6. Fuel stack; 61. Anode; 62. Cathode; 7. Heat box; 8. Burner; 9. Fan; 10. Steam boiler; 11. First regulating diverter valve; 12. Second regulating diverter valve; 13. Water heater; 14. Saturated steam generating section; 15. Steam superheating section; 16. Combustion chamber. DETAILED DESCRIPTION

[0074] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be construed as limiting the applicable scope of the present invention.

[0075] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0076] Example 1

[0077] This embodiment provides a solid oxide fuel cell cogeneration system, such as Figure 1 As shown, the system includes a heating module, a power generation module, a waste heat collection module, and a steam generation module;

[0078] The heating module includes a burner 8 , a fuel preheater 1 , and an air preheater 2 .

[0079] The fuel preheater 1 is used for preheating fuel, and the fuel preheater 1 is provided with a fuel inlet, a fuel outlet, a medium inlet and a medium outlet.

[0080] The air preheater 2 is used to preheat cathode intake air and is provided with a reaction air inlet, a reaction air outlet, a medium inlet and a medium outlet.

[0081] The burner 8 is used for combustion and heat supply, and provides heat for the system to heat up and operate stably at high temperature. The burner 8 is provided with a fuel inlet, a combustion-supporting inlet and an exhaust gas outlet.

[0082] The power generation module includes a balancing heat exchanger 3 , an anode heat exchanger 4 , a cathode heat exchanger 5 , a fuel cell stack 6 , a heat box 7 , a first regulating diverter valve 11 and a second regulating diverter valve 12 .

[0083] The balanced heat exchanger 3 is used to balance the heat exchange between the preheated fuel and the reaction air, so as to reduce the temperature difference between the anode inlet and the cathode inlet of the fuel cell stack 6. The balanced heat exchanger 3 is provided with a fuel inlet, a fuel outlet, a reaction air inlet, and a reaction air outlet.

[0084] The anode heat exchanger 4 is used to perform heat exchange on the fuel discharged from the balance heat exchanger 3. The anode heat exchanger 4 is provided with a fuel inlet, a fuel outlet, a medium inlet and a medium outlet.

[0085] The cathode heat exchanger 5 is used to exchange heat with the reaction air discharged from the balance heat exchanger 3. The cathode heat exchanger 5 is provided with a reaction air inlet, a reaction air outlet, a medium inlet and a medium outlet.

[0086] The stack 6 includes an anode 61 and a cathode 62 for performing an electrochemical reaction. The fuel loses electrons in the anode 61 and undergoes an oxidation reaction, and the electrons are output as electricity through an external circuit. The reaction air obtains electrons in the cathode 62 and undergoes a reduction reaction.

[0087] The anode 61 is provided with an anode inlet and an anode outlet, and an anode pipeline is connected therebetween. The cathode 62 is provided with a cathode inlet and a cathode outlet, and a cathode pipeline is connected therebetween.

[0088] The heat box 7 is used to maintain a uniform heat distribution of the core temperature of the battery stack 6. The battery stack 6 is placed in the heat box 7, which can play a role in heat preservation and temperature stabilization.

[0089] The first regulating diverter valve 11 can perform the first diversion of the anode tail gas discharged from the anode 61, control the amount of anode tail gas entering the balancing heat exchanger 3, and further control the circulation amount of the anode tail gas. The first regulating diverter valve 11 is a three-way valve with adjustable opening, having one inlet and two outlets. The inlet of the first regulating diverter valve 11 is connected to the medium outlet of the anode heat exchanger 4, and the outlet of the first regulating diverter valve 11 can be connected to the inlet of the second regulating diverter valve 12 and the inlet of the balancing heat exchanger 3 respectively.

[0090] The second regulating diverter valve 12 can perform a second diversion of at least part of the anode tail gas discharged from the first regulating diverter valve 11, and control the amount of anode tail gas entering the burner 8 and the steam boiler. The second regulating diverter valve 12 is a three-way valve with adjustable opening, having one inlet and two outlets, the inlet of the second regulating diverter valve 12 is connected to the outlet of the first regulating diverter valve 11, and the outlet of the second regulating diverter valve 12 can be connected to the fuel inlet of the burner 8 and the inlet of the steam generation module respectively.

[0091] By utilizing the first regulating diverter valve 11 and the second regulating diverter valve 12 to coordinately control the diversion of the anode tail gas, the efficiency of power generation, hot water production and steam production of the system can be simply and effectively adjusted.

[0092] The balancing heat exchanger 3, the anode heat exchanger 4 and the cathode heat exchanger 5 constitute the secondary balancing heat exchange system of the power generation module. The preheated fuel gas and the reaction air exchange heat once in the balancing heat exchanger 3, and then exchange heat again in the anode heat exchanger 4 and the cathode heat exchanger 5. The balancing heat exchanger 3, the anode heat exchanger 4, the cathode heat exchanger 5 and the heat box 7 can keep the temperature difference between the inside of the anode 61 and the anode inlet, the temperature difference between the inside of the cathode 62 and the cathode outlet, and the temperature difference of the stack 6 stable, so that the stack 6 is heated evenly during operation.

[0093] In the system provided in this embodiment, the waste heat collection module and the steam generation module are designed to be separated, which has the advantages of high fuel utilization, high steam quality, and stable product output.

[0094] The waste heat collection module is used to collect the heat provided by the heating module. The waste heat collection module includes a water heater 13. The water in the water heater 13 can absorb the waste heat of the heating module to produce hot water. The water heater 13 is provided with a medium inlet, a medium outlet, a water inlet, and a water outlet.

[0095] The steam generation module is used to produce steam, and can further produce superheated steam. The steam generation module includes a fan 9 and a steam boiler 10.

[0096] The steam boiler 10 includes a combustion chamber 16 and a steam generating chamber. The steam generating chamber is provided with a saturated steam generating section 14 and a steam superheating section 15, and a steam pipeline is connected between the saturated steam generating section 14 and the steam superheating section 15. Figure 1 As shown, the combustion chamber 16, the saturated steam generating section 14, and the steam superheating section 15 are arranged in sequence from bottom to top.

[0097] The combustion chamber 16 is provided with a fuel inlet and a combustion-supporting inlet. Heat is generated by combustion during combustion and the heat is transferred to the saturated steam generating section 14.

[0098] The saturated steam generating section 14 is filled with water for generating saturated steam. The saturated steam generating section 14 is provided with a first steam pipe and a first flue gas pipe ( Figure 1 The inlet of the first flue gas duct is connected to the combustion chamber 16, and the outlet of the first flue gas duct is located at the top of the saturated steam generating section 14. The inlet of the first steam duct is located at the bottom of the saturated steam generating section 14, and the outlet of the first steam duct is located at the top of the saturated steam generating section 14.

[0099] The steam superheating section 15 is provided with a second steam pipe and a second flue gas pipe ( Figure 1 The inlet of the second flue gas duct is connected to the outlet of the first flue gas duct for transmitting the combustion exhaust gas generated by the combustion chamber 16. The inlet of the second steam duct is located at the top of the steam superheating section 15, and the outlet of the second steam duct is located at the bottom of the steam superheating section 15. The inlet of the second steam duct is connected to the outlet of the first steam duct for transmitting steam. Specifically, a steam duct may be provided between the second steam duct and the first steam duct for connection.

[0100] In the steam generation module, the high-temperature combustion exhaust gas generated by the combustion chamber 16 moves upward along the first flue gas duct and the second flue gas duct in the steam boiler 10 in turn, providing a heat source for the saturated steam generating section 14 and the steam superheating section 15; the saturated steam generated by the saturated steam generating section 14 first moves upward along the first steam duct to the steam superheating section 15, and then moves downward along the second steam duct in the steam superheating section 15 to be converted into superheated steam through heat exchange with the high-temperature combustion exhaust gas. By adopting a two-stage cross-flow design (steam moves upward first and then downward) for the saturated steam generating section 14 and the steam superheating section 15, the contact time between water, saturated steam and high-temperature combustion exhaust gas in the steam boiler 10 can be increased, the degree of heat exchange can be improved, and superheated steam can be further produced on the basis of producing saturated steam.

[0101] The fan 9 is used to deliver combustion air to the steam boiler 10. The number of fans 9 can be selected according to actual conditions, and the fan 9 can be one or more than two. When there are more than two fans 9, the steam generation module can further include a bypass air duct, and each fan 9 can be connected to the combustion chamber 16 through the bypass air duct, and can be switched regularly to ensure stable operation of the system.

[0102] The connection relationship between the devices in the above system is:

[0103] The reaction air outlet of the air preheater 2 is connected to the reaction air inlet of the balancing heat exchanger 3, the reaction air outlet of the balancing heat exchanger 3 is connected to the reaction air inlet of the cathode heat exchanger 5, the reaction air outlet of the cathode heat exchanger 5 is connected to the inlet of the cathode 62, and the outlet of the cathode 62 is connected to the medium inlet of the cathode heat exchanger 5.

[0104] The fuel outlet of the fuel preheater 1 is connected to the fuel inlet of the balancing heat exchanger 3, the fuel outlet of the balancing heat exchanger 3 is connected to the fuel inlet of the anode heat exchanger 4, the fuel outlet of the anode heat exchanger 4 is connected to the inlet of the anode 61, the outlet of the anode 61 is connected to the medium inlet of the anode heat exchanger 4, and the medium outlet of the anode heat exchanger 4 is connected to the inlet of the first regulating diverter valve 11.

[0105] The outlet of the first regulating diverter valve 11 is connected to the inlet of the second regulating diverter valve 12; further, the outlet of the first regulating diverter valve 11 can also be connected to the inlet of the second regulating diverter valve 12 and / or the fuel inlet of the balancing heat exchanger 3. When the outlet of the first regulating diverter valve 11 is connected to the balancing heat exchanger 3, the outlet of the first regulating diverter valve 11 can be connected to the fuel inlet of the balancing heat exchanger 3 after being collected in the same pipeline with the fuel outlet of the fuel preheater 1.

[0106] The outlet of the second regulating diverter valve 12 is connected to the fuel inlet of the burner 8; further, the outlet of the second regulating diverter valve 12 can also be connected to the fuel inlet of the burner 8 and / or the fuel inlet of the combustion chamber 16 respectively.

[0107] The tail gas outlet of the burner 8 and the medium outlet of the cathode heat exchanger 5 are respectively connected to the medium inlet of the air preheater 2. Further, the tail gas outlet of the burner 8 and the medium outlet of the cathode heat exchanger 5 can be connected to the medium inlet of the air preheater 2 through the same pipeline. The medium outlet of the air preheater 2 is connected to the tail gas inlet of the fuel preheater 1, and the medium outlet of the fuel preheater 1 is connected to the medium inlet of the water heater 13.

[0108] Example 2

[0109] This embodiment provides a solid oxide fuel cell cogeneration method based on the system of Embodiment 1.

[0110] like Figure 2 As shown, the method includes:

[0111] 1. Disconnect the connection between the outlet of the first regulating diverter valve 11 and the fuel inlet of the balanced heat exchanger 3, open the connection between the outlet of the first regulating diverter valve 11 and the inlet of the second regulating diverter valve 12, open the connection between the outlet of the second regulating diverter valve 12 and the fuel inlet of the burner 8, and disconnect the connection between the outlet of the second regulating diverter valve 12 and the fuel inlet of the combustion chamber 16.

[0112] 2. The fuel gas enters the fuel preheater 1 for preheating, and the reaction air enters the air preheater 2 for preheating, so that the fuel gas and reaction air are heated;

[0113] The heated fuel gas and reaction air are subjected to balanced heat exchange in the balanced heat exchanger 3 to balance the temperature of the fuel gas and the reaction air. Then, the fuel gas is transported from the balanced heat exchanger 3 to the anode heat exchanger 4, and the reaction air is transported from the balanced heat exchanger 3 to the cathode heat exchanger 5.

[0114] The fuel gas is heat exchanged in the anode heat exchanger 4, and the temperature of the fuel gas after heat exchange reaches the working temperature of the fuel cell stack 6, and enters the anode 61 of the fuel cell stack 6;

[0115] The reaction air is heat exchanged in the cathode heat exchanger 5 , and the temperature of the reaction air after the heat exchange reaches the operating temperature of the fuel cell stack 6 , and enters the cathode 62 of the fuel cell stack 6 .

[0116] 3. The fuel gas loses electrons in the anode 61 of the stack 6 and undergoes an oxidation reaction, and the reaction air gains electrons in the cathode 62 of the stack 6 and undergoes a reduction reaction; for example, when the fuel gas is hydrogen, the hydrogen loses electrons in the anode 61 and reacts with the oxygen. 2-Combine to generate H2O, and the oxygen in the reacting air gains electrons at the cathode 62 to generate O 2- ;

[0117] The anode tail gas generated by the anode 61 enters the anode heat exchanger 4 to provide a heat source for the heat exchange process of the fuel gas in the anode heat exchanger 4, and the cathode tail gas generated by the cathode 62 enters the cathode heat exchanger 5 to provide a heat source for the heat exchange process of the reaction air in the cathode heat exchanger 5.

[0118] 4. The anode tail gas discharged from the anode heat exchanger 4 all enters the second regulating diverter valve 12 through the first regulating diverter valve 11 , and the second regulating diverter valve 12 transports all the anode tail gas to the burner 8 .

[0119] 5. The anode tail gas transported to the burner 8 burns with the combustion air to generate heat. The intake ratio of the combustion air to the anode tail gas is 3-6, so as to accelerate the discharge of the heat generated by the fuel cell stack 6 and maintain the thermal balance of the power generation module and the stable operation of the system.

[0120] 6. The combustion tail gas generated in the burner 8 is mixed with the cathode tail gas discharged from the cathode heat exchanger 5 and enters the air preheater 2, the fuel preheater 1 and the water heater 13 in sequence, providing a heat source for the preheating process of the reaction air in the air preheater 2, the preheating process of the fuel gas in the fuel preheater 1, and the heating process of the water in the water heater 13. The water in the water heater 13 is heated by heat exchange to produce hot water. By adjusting the flow rate of water in the water heater 13, the temperature of the hot water product and the waste heat utilization rate of the system can be controlled.

[0121] The above method provided in this embodiment adopts a cogeneration mode. In the above operation mode, the steam production efficiency is 0, and the hot water production efficiency is relatively high. The ratio of the hot water production efficiency to the power generation efficiency is 0.8-2.1.

[0122] In the method provided in this embodiment, by disconnecting the connection between the outlet of the first regulating diverter valve 11 and the balancing heat exchanger 3, and disconnecting the connection between the outlet of the second regulating diverter valve 12 and the combustion chamber 16, all the anode tail gas discharged from the anode heat exchanger 4 can be controlled to enter the burner 8 and burn with excess combustion air, thereby accelerating the system heating.

[0123] Example 3

[0124] This embodiment provides another solid oxide fuel cell cogeneration method based on the system of embodiment 1. Figure 3 As shown, the method includes:

[0125] 1. Make the outlet of the first regulating diverter valve 11 connected to the fuel inlet of the balancing heat exchanger 3 and the inlet of the second regulating diverter valve 12 at the same time, open the connection between the outlet of the second regulating diverter valve 12 and the fuel inlet of the burner 8, and disconnect the connection between the outlet of the second regulating diverter valve 12 and the fuel inlet of the combustion chamber 16.

[0126] 2. The fuel gas enters the fuel preheater 1 for preheating, and the reaction air enters the air preheater 2 for preheating, so that the fuel gas and reaction air are heated;

[0127] The heated fuel gas and reaction air are subjected to balanced heat exchange in the balanced heat exchanger 3 to balance the temperature of the fuel gas and the reaction air. Then, the fuel gas is transported from the balanced heat exchanger 3 to the anode heat exchanger 4, and the reaction air is transported from the balanced heat exchanger 3 to the cathode heat exchanger 5.

[0128] The fuel gas is heat exchanged in the anode heat exchanger 4, and the temperature of the fuel gas after heat exchange reaches the working temperature of the fuel cell stack 6, and enters the anode 61 of the fuel cell stack 6;

[0129] The reaction air is heat exchanged in the cathode heat exchanger 5 , and the temperature of the reaction air after the heat exchange reaches the operating temperature of the fuel cell stack 6 , and enters the cathode 62 of the fuel cell stack 6 .

[0130] 3. The fuel gas loses electrons in the anode 61 of the stack 6 and undergoes an oxidation reaction, and the reaction air gains electrons in the cathode 62 of the stack 6 and undergoes a reduction reaction; for example, when the fuel gas is hydrogen, the hydrogen loses electrons in the anode 61 and reacts with the oxygen. 2- Combine to generate H2O, and the oxygen in the reacting air gains electrons at the cathode 62 to generate O 2- ;

[0131] The anode tail gas generated by the anode 61 enters the anode heat exchanger 4 to provide a heat source for the heat exchange process of the fuel gas in the anode heat exchanger 4, and the cathode tail gas generated by the cathode 62 enters the cathode heat exchanger 5 to provide a heat source for the heat exchange process of the reaction air in the cathode heat exchanger 5.

[0132] 4. A portion of the anode tail gas discharged from the anode heat exchanger 4 flows through the first regulating diverter valve 11 and into the balancing heat exchanger 3 in parallel with the fuel discharged from the fuel preheater 1, and enters the anode 61 of the fuel cell stack 6 through the balancing heat exchanger 3 and the anode heat exchanger 4. This process recovers the anode tail gas discharged from the anode and inputs it into the anode 61 as fuel again, which is the anode tail gas circulation process; the remaining anode tail gas discharged from the anode heat exchanger 4 is transported to the burner 8 via the first regulating diverter valve 11 and the second regulating diverter valve 12 in sequence.

[0133] 5. The anode tail gas transported to the burner 8 burns with the combustion air to generate heat and produce combustion tail gas; the intake ratio of the combustion air to the anode tail gas is 7-10.

[0134] 6. The combustion tail gas is mixed with the cathode tail gas discharged from the cathode heat exchanger 5 and enters the air preheater 2, the fuel preheater 1 and the water heater 13 in sequence, providing heat sources for the preheating process of the reaction air in the air preheater 2, the preheating process of the fuel gas in the fuel preheater 1, and the heating process of the water in the water heater 13. The water in the water heater 13 is heated by heat exchange to produce hot water.

[0135] The above method provided in this embodiment adopts a power generation mode combining anode tail gas recovery and tail gas combustion. In the above operation mode, the power generation efficiency is higher than the hot water output efficiency, and the steam output efficiency is 0. The ratio of hot water output efficiency to power generation efficiency is about 0.4-0.95.

[0136] Compared with Example 2, during the operation of Example 3, part of the anode tail gas enters the balance heat exchanger 3 to realize the anode tail gas circulation, which can greatly improve the system electrical efficiency; while in Example 2, all the anode tail gas enters the burner and is burned and converted into heat, which can provide more heat sources for the air preheater 2, the fuel preheater 1 and the water heater 13. Therefore, the hot water efficiency of Example 2 is higher than that of Example 3, and the power generation efficiency of Example 3 is higher than that of Example 2.

[0137] Example 4

[0138] This embodiment provides another solid oxide fuel cell cogeneration method based on the system of embodiment 1. Figure 4 As shown, the method includes:

[0139] 1. Disconnect the connection between the outlet of the first regulating diverter valve 11 and the fuel inlet of the balanced heat exchanger 3, connect the outlet of the first regulating diverter valve 11 and the inlet of the second regulating diverter valve 12, and make the outlet of the second regulating diverter valve 12 connected to the fuel inlet of the burner 8 and the fuel inlet of the combustion chamber 16 at the same time.

[0140] 2. The fuel gas enters the fuel preheater 1 for preheating, and the reaction air enters the air preheater 2 for preheating, so that the fuel gas and reaction air are heated;

[0141] The heated fuel gas and reaction air are subjected to balanced heat exchange in the balanced heat exchanger 3 to balance the temperature of the fuel gas and the reaction air. Then, the fuel gas is transported from the balanced heat exchanger 3 to the anode heat exchanger 4, and the reaction air is transported from the balanced heat exchanger 3 to the cathode heat exchanger 5.

[0142] The fuel gas is heat exchanged in the anode heat exchanger 4, and the temperature of the fuel gas after heat exchange reaches the working temperature of the fuel cell stack 6, and enters the anode 61 of the fuel cell stack 6;

[0143] The reaction air is heat exchanged in the cathode heat exchanger 5 , and the temperature of the reaction air after the heat exchange reaches the operating temperature of the fuel cell stack 6 , and enters the cathode 62 of the fuel cell stack 6 .

[0144] 3. The fuel gas loses electrons in the anode 61 of the stack 6 and undergoes an oxidation reaction, and the reaction air gains electrons in the cathode 62 of the stack 6 and undergoes a reduction reaction; for example, when the fuel gas is hydrogen, the hydrogen loses electrons in the anode 61 and reacts with the oxygen. 2- Combine to generate H2O, and the oxygen in the reacting air gains electrons at the cathode 62 to generate O 2- ;

[0145] The anode tail gas generated by the anode 61 enters the anode heat exchanger 4 to provide a heat source for the heat exchange process carried out in the anode heat exchanger 4 ; the cathode tail gas generated by the cathode 62 enters the cathode heat exchanger 5 to provide a heat source for the heat exchange process carried out in the cathode heat exchanger 5 .

[0146] 4. The anode tail gas discharged from the anode heat exchanger 4 all enters the second regulating diverter valve 12 through the first regulating diverter valve 11. The second regulating diverter valve 12 delivers a small part (less than 10 vol%) of the anode tail gas to the burner 8, and delivers the remaining (more than 90 vol%) of the anode tail gas to the combustion chamber 16 of the steam boiler 10.

[0147] 5. The anode tail gas transported to the burner 8 burns with the combustion-supporting air to generate heat. The generated combustion tail gas is mixed with the cathode tail gas discharged from the cathode heat exchanger 5 and then enters the air preheater 2, the fuel preheater 1 and the water heater 13 in sequence, providing a heat source for the preheating process of the reaction air in the air preheater 2, the preheating process of the fuel gas in the fuel preheater 1, and the heating process of the water in the water heater 13. The water in the water heater 13 is heated and heated to produce hot water.

[0148] 6. The fan 9 is used to deliver combustion air to the combustion chamber 16. The combustion air and the anode tail gas delivered to the steam boiler 10 are burned in the combustion chamber 16 to generate heat and flue gas. The generated heat is carried by the flue gas and sequentially enters the first flue gas duct of the saturated steam generating section 14 and the second flue gas duct of the steam superheating section 15;

[0149] The water in the first steam pipe in the saturated steam generating section 14 exchanges heat with the flue gas in the first flue gas pipe, and the water is evaporated by heat and converted into saturated steam. The saturated steam moves upward and enters the top inlet of the steam superheating section 15 through the steam pipe from the top outlet of the saturated steam generating section 14; the saturated steam moves downward along the second steam pipe in the steam superheating section 15 and fully exchanges heat with the flue gas moving upward in the second flue gas pipe. After the heat exchange, the saturated steam is heated and converted into superheated steam, and the superheated steam is discharged from the outlet of the steam superheating section 15; the flue gas after the heat exchange is discharged from the outlet of the second flue gas pipe of the steam superheating section 15. The quality and output of the output steam can be controlled by adjusting the pure water feed amount of the first steam pipe in the steam boiler 10.

[0150] The method provided in this embodiment adopts a steam-electricity cogeneration mode. In the above operation mode, the steam boiler 10 can produce high-quality superheated steam at 160-250°C and 0.6-1.0MPa, and the ratio of steam efficiency to power generation efficiency can reach 0.6-1.8.

[0151] The solid oxide fuel cell cogeneration system provided by the present invention has multiple operating modes such as power generation, cogeneration of heat and power, and cogeneration of steam and power. There is no order requirement for different operating modes, and they can be flexibly switched to meet the dynamic needs of different application ends for steam, electricity, and heat. In addition, the above-mentioned system provided by the present invention has a multi-stage balanced heat exchange system, which can make the power generation module (especially the stack) heated evenly and keep the ambient temperature stable, which is conducive to the long-term stable operation of the system. The fuel utilization rate of the above-mentioned system is high, which can reach more than 65%; the operation method is simple, the structure is efficient and compact, and the comprehensive utilization efficiency of the system is more than 80% in the three operating modes.

Claims

1. A solid oxide fuel cell cogeneration system, wherein: The system includes a heating module and a power generation module; The heating module comprises a burner (8), a fuel preheater (1), and an air preheater (2); The power generation module comprises a balancing heat exchanger (3), an anode heat exchanger (4), a cathode heat exchanger (5), and a fuel cell stack (6); the fuel cell stack (6) is provided with an anode (61) and a cathode (62); The reaction air outlet of the air preheater (2) is connected to the reaction air inlet of the balancing heat exchanger (3), the reaction air outlet of the balancing heat exchanger (3) is connected to the reaction air inlet of the cathode heat exchanger (5), the reaction air outlet of the cathode heat exchanger (5) is connected to the inlet of the cathode (62), and the outlet of the cathode (62) is connected to the medium inlet of the cathode heat exchanger (5); The fuel outlet of the fuel preheater (1) is connected to the fuel inlet of the balancing heat exchanger (3), the fuel outlet of the balancing heat exchanger (3) is connected to the fuel inlet of the anode heat exchanger (4), the fuel outlet of the anode heat exchanger (4) is connected to the inlet of the anode (61), the outlet of the anode (61) is connected to the medium inlet of the anode heat exchanger (4); the medium outlet of the anode heat exchanger (4) is connected to the fuel inlet of the burner (8); The tail gas outlet of the burner (8) is connected to the medium inlet of the air preheater (2), and the medium outlet of the air preheater (2) is connected to the medium inlet of the fuel preheater (1).

2. The system according to claim 1, wherein: The medium outlet of the cathode heat exchanger (5) is also connected to the medium inlet of the air preheater (2).

3. According to the system of claim 1 or 2, the medium outlet of the anode heat exchanger (4) is also connected to the fuel inlet of the balancing heat exchanger (3).

4. The system according to claim 3, wherein: The power generation module comprises a first regulating diverter valve (11) and a second regulating diverter valve (12); the inlet of the first regulating diverter valve (11) is connected to the medium outlet of the anode heat exchanger (4); the outlet of the first regulating diverter valve (11) is respectively connected to the inlet of the second regulating diverter valve (12) and the fuel inlet of the balancing heat exchanger (3); the outlet of the second regulating diverter valve (12) is connected to the fuel inlet of the burner (8).

5. The system according to any one of claims 1 to 4, wherein: The system further comprises a waste heat collection module, the inlet of which is connected to the tail gas outlet of the burner (8) and / or the medium outlet of the cathode heat exchanger (5); Preferably, the waste heat collection module comprises a water heater (13).

6. The system according to any one of claims 1 to 5, wherein: The system further comprises a steam generation module, and the medium outlet of the anode heat exchanger (4) is also connected to the fuel inlet of the steam generation module; Preferably, when the power generation module comprises a second regulating diverter valve (12), the outlet of the second regulating diverter valve (12) is respectively connected to the fuel inlet of the burner (8) and the fuel inlet of the steam generation module.

7. The system according to claim 6, wherein: The steam generation module comprises a steam boiler (10), wherein the steam boiler (10) comprises a combustion chamber (16) and a steam generation chamber, wherein the combustion chamber (16) is used to perform a combustion reaction and supply heat to the steam generation chamber, and the steam generation chamber is used to produce steam.

8. The system according to claim 7, wherein: The steam generating chamber comprises a saturated steam generating section (14) and a steam superheating section (15); The saturated steam generating section (14) is provided with a first flue gas duct and a first steam duct capable of exchanging heat with each other, the steam superheating section (15) is provided with a second flue gas duct and a second steam duct capable of exchanging heat with each other, the combustion chamber (16), the first flue gas duct, and the second flue gas duct are connected in sequence, and the first steam duct and the second steam duct are connected; Preferably, the inlet-to-outlet direction of the first steam conduit is opposite to the inlet-to-outlet direction of the second steam conduit.

9. A solid oxide fuel cell cogeneration method, the method being carried out in the solid oxide fuel cell cogeneration system according to any one of claims 1 to 8, the method comprising: The fuel gas enters the fuel preheater (1) for preheating, the reaction air enters the air preheater (2) for preheating, and the preheated fuel gas and reaction air enter the balance heat exchanger (3) for balance heat exchange; The reaction air that has undergone balanced heat exchange is heated in the cathode heat exchanger (5), and the heated reaction air enters the cathode (62) to undergo a reduction reaction to produce cathode tail gas; the cathode tail gas discharged from the cathode (62) enters the cathode heat exchanger (5) to exchange heat with the reaction air; The fuel gas that has undergone balanced heat exchange is heated in the anode heat exchanger (4), and the heated fuel gas enters the anode (61) to undergo an oxidation reaction to generate anode tail gas; the anode tail gas discharged from the anode (61) is transported to the anode heat exchanger (4) to exchange heat with the fuel gas, and the anode tail gas after heat exchange enters the burner (8), and the anode tail gas is burned with the combustion-supporting air in the burner (8) to generate heat to generate combustion tail gas, which is discharged from the burner (8); The combustion exhaust gas discharged from the burner (8) is transported to the air preheater (2) and the fuel preheater (1) as a heat source.

10. The method according to claim 9, wherein: When the solid oxide fuel cell cogeneration system includes a waste heat collection module, the method further includes: conveying the combustion tail gas discharged from the burner (8) to the waste heat collection module as a heat source; Preferably, the method comprises: conveying the combustion exhaust gas discharged from the burner (8) to the air preheater (2), the fuel preheater (1), and the waste heat collection module in sequence as a heat source.

11. The method according to claim 9 or 10, wherein: When the solid oxide fuel cell cogeneration system includes a waste heat collection module, the method further includes: transporting the cathode tail gas that has undergone heat exchange in the cathode heat exchanger (5) to at least one of the air preheater (2), the fuel preheater (1), and the waste heat collection module as a heat source.

12. The method according to any one of claims 9 to 11, wherein: When the medium outlet of the anode heat exchanger (4) is respectively connected to the fuel inlet of the burner (8) and the fuel inlet of the balancing heat exchanger (3), the method further comprises: transporting the anode tail gas discharged from the anode heat exchanger (4) to the fuel inlet of the burner (8) and the fuel inlet of the balancing heat exchanger (3), respectively, the anode tail gas undergoing balanced heat exchange in the balancing heat exchanger (3), and the anode tail gas undergoing balanced heat exchange enters the anode (61) after heat exchange via the anode heat exchanger (4).

13. The method according to any one of claims 9 to 11, wherein: The system further comprises a steam generation module, and when the medium outlet of the anode heat exchanger (4) is respectively connected to the fuel inlet of the burner (8) and the fuel inlet of the steam generation module, the method further comprises: The anode tail gas discharged from the anode heat exchanger (4) is respectively transported to the fuel inlet of the burner (8) and the steam generation module. The anode tail gas is burned in the steam generation module to generate heat, so that water in the steam generation module is evaporated by the heat to generate superheated steam.

14. The method according to claim 13, wherein: The superheated steam production process includes: The anode tail gas is burned with combustion-supporting air in the combustion chamber (16) to generate flue gas, which is transmitted to the saturated steam generating section (14) and the steam superheating section (15) in sequence. The flue gas exchanges heat with water in the saturated steam generating section (14), causing the water to evaporate and be converted into steam. The steam enters the steam superheating section (15) to exchange heat with the flue gas, and the steam is heated and converted into superheated steam.

15. The method according to claim 13 or 14, wherein: The temperature of the superheated steam is 160° C. to 250° C., and the pressure of the superheated steam is 0.6 MPa to 1.0 MPa.

16. The method according to any one of claims 13 to 15, wherein: When the medium outlet of the anode heat exchanger (4) is respectively connected to the fuel inlet of the burner (8) and the fuel inlet of the steam generation module, taking the total volume of the anode tail gas discharged from the anode heat exchanger (4) as 100%, the volume of the anode tail gas entering the burner (8) from the anode heat exchanger (4) is less than 10%, and the volume of the anode tail gas entering the steam generation module from the anode heat exchanger (4) is more than 90%.

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