A method for controlling water-carbon ratio of a fuel cell and a fuel cell system

Abstract

The present application relates to a kind of water carbon ratio control method of fuel cell and fuel cell system, belong to fuel cell technical field.The present application is imported into the anode of first stack group, and the gas is reacted in first stack group, and the gas not participating in reaction is discharged from the anode of first stack group;The discharged gas is treated to remove water, to remove part of water vapor, and the water carbon ratio of gas after water removal treatment is (1.2-3.5):1;The treated gas is input into the anode of second stack group.The first stack group and second stack group of the present application can be respectively current load, and the water vapor content in the gas discharged from first stack group is high, the present application is treated to remove water to the gas discharged from step first stack group, to remove part of water vapor, realizes the regulation and control of the water carbon ratio of the gas input into second stack group, to improve the gas utilization rate, while significantly improve the power generation efficiency of fuel cell system.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a method for controlling the water-to-carbon ratio of a fuel cell and a fuel cell system. Background Technology

[0002] In recent years, with the continuous consumption of fossil fuels, energy and environmental issues have increasingly constrained economic development. A fuel cell is an electrochemical device that directly converts the chemical energy stored in fuel and oxidizing gases into electrical energy. Since the 1940s, four generations of fuel cells have been developed: the first generation includes alkaline fuel cells (AFC) and phosphoric acid fuel cells (PAFC); the second generation includes molten carbonate fuel cells (MCFC); the third generation includes solid oxide fuel cells (SOFC); and the fourth generation includes proton exchange membrane fuel cells (PEMFC) and direct methanol fuel cells. Among these, solid oxide fuel cells, as a new type of highly efficient clean energy, offer a potentially promising optimization solution for sustainable development.

[0003] To improve the overall fuel utilization rate of the system, existing solid oxide fuel cells (SOFCs) will input the gas discharged from the anode of the stack into another stack for reuse, thereby improving the utilization rate of the gas. However, the gas discharged from the anode of the stack often contains a large amount of water vapor, which makes the water-to-carbon ratio in the discharged gas often too low, affecting the power generation efficiency of the fuel cell when reused.

[0004] Therefore, it is essential to develop a method for controlling the water-to-carbon ratio of fuel cells to improve both fuel gas utilization and system power generation efficiency. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for controlling the water-to-carbon ratio of a fuel cell and a fuel cell system. In this invention, the first and second fuel cell stacks are subjected to current loading. The gas discharged from the first fuel cell stack has a high water vapor content. This invention performs water removal treatment on the gas discharged from the first fuel cell stack to remove some water vapor, thereby controlling the water-to-carbon ratio of the gas input to the second fuel cell stack. This significantly improves the power generation efficiency of the fuel cell system while improving the gas utilization rate.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for controlling the water-to-carbon ratio of a fuel cell, comprising the following steps:

[0008] (1) Gas is introduced into the anode of the first fuel cell stack. After the gas reacts in the first fuel cell stack, the gas that does not participate in the reaction is discharged from the anode of the first fuel cell stack.

[0009] (2) The exhaust gas is treated to remove water vapor. After the water removal treatment, the water-to-carbon ratio of the gas is (1.2-3.5):1.

[0010] (3) Input the treated gas into the anode of the second fuel cell stack.

[0011] In this invention, the first and second fuel cell stacks can be subjected to current loading respectively. Gas is introduced into the first fuel cell stack through the first anode inlet pipe. After the gas reacts in the first fuel cell stack, the excess gas is discharged from the anode outlet channel of the first fuel cell stack. The discharged gas has a high water vapor content. This invention performs water removal treatment on the gas discharged from the first fuel cell stack in step 1 to remove some water vapor and adjusts the water content of the gas introduced into the second fuel cell stack, adjusting the water-to-carbon ratio of the gas to (1.2~3.5):1, thereby significantly improving the power generation efficiency of the fuel cell system while improving the gas utilization rate.

[0012] The water-to-carbon ratio described in this invention refers to the ratio of the total number of water vapor molecules in the intake air to the total number of carbon atoms excluding carbon dioxide per unit time.

[0013] In a preferred embodiment of the present invention, in step (1), the temperature of the discharged gas is 700-780°C.

[0014] As a preferred embodiment of the present invention, step (2) specifically includes: inputting the discharged gas into the water controller for condensation and dehydration, so that the temperature of the gas drops to 44-64°C to remove some water vapor, and adjusting the water-to-carbon ratio of the gas to (1.2-3.5):1.

[0015] In a preferred embodiment of the present invention, step (2) specifically includes:

[0016] The discharged gas is fed into the first heat exchanger for heat exchange to obtain gas A1, the temperature of which is 70-100℃.

[0017] Gas A1 is fed into a water controller for condensation and dehydration to remove some water vapor, yielding gas A2. The temperature of gas A2 is 44–64°C, and the water-to-carbon ratio of gas A2 is (1.2–3.5):1.

[0018] Gas A2 is fed into the first heat exchanger for heat exchange to obtain processed gas with a temperature of 550–650°C.

[0019] In the first heat exchanger, the condensed and dehydrated gas (i.e. gas A2) exchanges heat with the discharged gas, realizing the self-heating of the gas and making full use of the gas's thermal energy. This results in a smaller temperature difference between the gas in the first and second fuel cell stacks, which is beneficial to improving the overall efficiency of the system.

[0020] In a preferred embodiment of the present invention, step (2) specifically includes:

[0021] The discharged gas is fed into the first heat exchanger for the first heat exchange to obtain gas B1, the temperature of which is 380-420℃.

[0022] Gas B1 is fed into the second heat exchanger for a second heat exchange to obtain gas B2, the temperature of gas B2 being 70-100℃.

[0023] Gas B2 is fed into a water controller for condensation and dehydration to remove some water vapor, yielding gas B3. The temperature of gas B3 is 44–64°C, and the water-to-carbon ratio of gas B3 is (1.2–3.5):1.

[0024] The gas B3 is fed into the first heat exchanger for heat exchange to obtain processed gas with a temperature of 550-650℃.

[0025] This invention achieves gradient cooling of high-temperature gas through a first heat exchanger and a second heat exchanger, resulting in high efficiency. In the first heat exchanger, the gas after condensation and dehydration is exchanged with the discharged gas, realizing the self-heating of the gas. This results in a smaller temperature difference between the gas in the first and second fuel cell stacks, which is beneficial to improving the overall efficiency of the system.

[0026] Secondly, the present invention provides a fuel cell system comprising a first fuel cell stack, a second fuel cell stack, and a water control device. The anode inlet channel of the first fuel cell stack is connected to a first anode inlet pipe, the anode outlet channel of the first fuel cell stack is connected to the inlet of the water control device, the outlet of the water control device is connected to the anode inlet channel of the second fuel cell stack, and the anode outlet channel of the second fuel cell stack is connected to a second anode outlet pipe.

[0027] In this invention, the first and second fuel cell stacks can be subjected to current loading respectively. Gas is introduced into the first fuel cell stack through the first anode inlet pipe. After the gas reacts in the first fuel cell stack, the excess gas is discharged from the anode outlet channel of the first fuel cell stack. The discharged gas has a high water vapor content. By setting a water control device between the first and second fuel cell stacks, the discharged gas is passed into the water control device to remove water, thereby significantly reducing the water content of the gas entering the second fuel cell stack. This significantly improves the power generation efficiency of the fuel cell system while improving the gas utilization rate.

[0028] In a preferred embodiment of the present invention, the water control device includes a water controller.

[0029] The outlet of the water controller is connected to a first recovery pipe. The first recovery pipe is used to connect to the gas supply device of the fuel cell system, so that the discharged water can be recycled in the fuel cell system, significantly improving the water utilization efficiency.

[0030] In a preferred embodiment of the present invention, the water control device includes a water controller and a first heat exchanger. The anode outlet channel of the first fuel cell stack is connected to the first medium inlet of the first heat exchanger. The first medium outlet of the first heat exchanger is connected to the air inlet of the water controller through a pipe. The air outlet of the water controller is connected to the second medium inlet of the first heat exchanger through a pipe. The second medium outlet of the first heat exchanger is connected to the anode inlet channel of the second fuel cell stack.

[0031] Because the fuel cell stack operates at a high temperature, the gas flow exiting from the anode outlet of the first stack has a high temperature. This high-temperature gas flows into the first heat exchanger for heat exchange and cooling, then flows into the water controller for dewatering and further cooling. The gas flow exiting the water controller returns to the first heat exchanger for heat exchange and reheating, thus achieving self-heating of the gas flow. Therefore, this invention, through the first heat exchanger and the water controller, can fully utilize the thermal energy of the exhaust gas, improving the gas utilization rate and power generation efficiency of the fuel cell system.

[0032] Furthermore, the water control device also includes a second heat exchanger, which is disposed on the pipeline between the first heat exchanger and the water controller. The first medium outlet of the first heat exchanger is connected to the first medium inlet of the second heat exchanger through a pipeline. The first medium outlet of the second heat exchanger is connected to the air inlet of the water controller through a pipeline. The water outlet of the water controller is connected to the second medium inlet of the second heat exchanger through a pipeline.

[0033] The fuel gas discharged from the anode outlet channel of the first fuel cell stack flows into the first heat exchanger for heat exchange and cooling, then flows into the second heat exchanger for further cooling, and then flows into the water controller to remove water. The temperature of the dehydrated fuel gas stream is relatively low, and it flows back into the first heat exchanger to be heated before entering the second fuel cell stack. This invention fully utilizes the thermal energy of the discharged fuel gas stream through the first and second heat exchangers. After water removal, no external heating is required, which reduces costs while improving the fuel gas utilization rate and power generation efficiency of the fuel cell system.

[0034] Furthermore, a thermostat is installed inside the water controller, which is used to adjust the temperature inside the water controller.

[0035] Furthermore, the temperature controller can be any one of a resistance heater, an induction heater, an electric arc heater, or a medium heat exchanger.

[0036] In this invention, the water controller has a water tank, the air inlet of the water controller is located on the water tank, an air inlet pipe is provided inside the water tank, one end of the air inlet pipe is connected to the air inlet, and the other end of the air inlet pipe extends into the water in the lower part of the water tank; the air outlet of the water controller is located at the upper part of the water tank, and the water outlet of the water controller is located at the bottom of the water tank.

[0037] This invention uses a thermostat to control the temperature within the water controller at 44–64°C. When the water content in the fuel gas entering the water controller is high, lowering the temperature of the water controller can achieve a good water removal effect. Research has shown that controlling the temperature within the water controller at 44–64°C can control the water-to-carbon ratio in the fuel gas entering the second fuel cell stack at 1.2–3.5. This invention achieves regulation of the water-to-carbon ratio in the fuel intake air of the second fuel cell stack by adjusting the temperature within the water controller.

[0038] Furthermore, the temperature controller is a medium heat exchanger, and the water controller contains a medium heat exchanger. The medium introduced into the medium heat exchanger includes any one of water, steam, oil, and ethylene glycol. In this invention, the medium introduced into the medium heat exchanger is preferably water, and the medium outlet of the medium heat exchanger is connected to the second medium inlet of the second heat exchanger via a pipe.

[0039] In a preferred embodiment of the present invention, the housing of the first fuel cell stack is provided with a cathode inlet pipe or inlet on the cathode side, and the housing of the first fuel cell stack is provided with a cathode outlet pipe or cathode outlet on the cathode side; the housing of the second fuel cell stack is provided with a cathode inlet pipe or cathode inlet on the cathode side, and the housing of the second fuel cell stack is provided with a cathode outlet pipe or cathode outlet on the cathode side.

[0040] This invention introduces oxidizing gases (such as air, oxygen, etc.) into each fuel cell stack in parallel, which can reduce the internal temperature difference between the first and second fuel cell stacks, maintain the thermal balance of the fuel cell system, and effectively delay the aging of the fuel cell system.

[0041] Furthermore, the water controller, the first heat exchanger, and the second heat exchanger are integrated and installed inside the housing.

[0042] In a preferred embodiment of the present invention, the number of fuel cells in the first fuel cell stack group is not less than one, and the number of fuel cells in the second fuel cell stack group is not less than one.

[0043] Furthermore, the ratio of the number of fuel cell stacks in the first fuel cell stack group to the number of fuel cell stacks in the second fuel cell stack group is (1-7):1. If the above conditions are met, the fuel cell system has good robustness and can maintain the fuel cell system in the optimal thermal management mode. If the ratio of the number of fuel cell stacks in the first fuel cell stack group to the number of fuel cell stacks in the second fuel cell stack group is greater than 7:1, it will cause the temperature of the second fuel cell stack group to be too high, resulting in a large temperature difference between the anode inlet channel and the anode outlet channel in the second fuel cell stack group, which will affect the fuel cell stack life and power generation performance. If the ratio of the number of fuel cell stacks in the first fuel cell stack group to the number of fuel cell stacks in the second fuel cell stack group is less than 1:1, the gas flow entering the anode of the second fuel cell stack group and the water recycled into the system will not reach a suitable temperature, and further heating treatment will be required, which will lead to a decrease in the efficiency of the fuel cell system.

[0044] Furthermore, the first fuel cell stack group has at least two fuel cell stacks, and the oxidizing gas (such as air, oxygen, etc.) in each fuel cell stack is input into each fuel cell stack in parallel; the second fuel cell stack group has at least two fuel cell stacks, and the oxidizing gas (such as air, oxygen, etc.) in each fuel cell stack is input into each fuel cell stack in parallel.

[0045] In this invention, the water-to-carbon ratio control method for a fuel cell described in the first aspect is implemented through the fuel cell system described in the second aspect.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] The first and second fuel cell stacks of the present invention can be subjected to current loading respectively. The gas discharged from the first fuel cell stack has a high water vapor content. The present invention performs water removal treatment on the gas discharged from the first fuel cell stack to remove some water vapor, thereby achieving water-carbon ratio regulation of the gas input to the second fuel cell stack. This significantly improves the power generation efficiency of the fuel cell system while improving the gas utilization rate. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the structure of the fuel cell system provided in Embodiment 1 of the present invention;

[0049] Figure 2 This is a schematic diagram of the structure of the fuel cell system provided in Embodiment 2 of the present invention;

[0050] Figure 3 This is a schematic diagram of the fuel cell system provided in Embodiment 3 of the present invention;

[0051] Figure 4 This is a schematic diagram of the structure of the fuel cell system provided in Embodiment 4 of the present invention.

[0052] In the figure, 1-first fuel cell stack, 2-second fuel cell stack, 3-water control device, 31-water controller, 32-first heat exchanger, 33-second heat exchanger, 34-first recovery pipe, 35-second recovery pipe, 36-medium input pipe, 4-first anode inlet pipe, 5-first anode outlet pipe, 6-second anode inlet pipe, 7-second anode outlet pipe, 8-cathode inlet pipe, 9-cathode outlet pipe. Detailed Implementation

[0053] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0054] In the following embodiments, sampling tubes are respectively provided on the first anode outlet pipe 5 and the second anode inlet pipe 6. In the above embodiments, the water-to-carbon ratio is measured by the following method:

[0055] Gas samples were obtained through sampling tubes, and the contents of CH4, CO, and H2O in the gas were detected using a high-temperature infrared flue gas analyzer. The water-carbon ratio is the ratio of H2O content to the sum of CH4 and CO contents, i.e., H2O content: (CH4 content + CO content).

[0056] In the following embodiments, each pipe is equipped with a control valve to control the opening and closing of each pipe; each pipe is also equipped with a temperature sensor and a pressure gauge to monitor the temperature and pressure of the fluid in each pipe; a temperature sensor is installed in the water tank of the water controller 31 to monitor the water temperature in the water tank.

[0057] It is understood that in the following embodiments, the fuel cells in the first fuel cell stack 1, the fuel cells in the second fuel cell stack 2, the first heat exchanger 32 and the second heat exchanger 33 are all commercially available products, and appropriate brands and models can be selected according to actual needs.

[0058] Example 1

[0059] Please see Figure 1 The fuel cell system provided in this embodiment includes a first stack 1, a second stack 2, and a water control device 3.

[0060] The anode air inlet channel of the first fuel cell stack 1 is connected to the first anode air inlet pipe 4. The anode air outlet channel of the first fuel cell stack 1 is connected to the air inlet of the water control device 3 through the first anode air outlet pipe 5. The air outlet of the water control device 3 is connected to the anode air inlet channel of the second fuel cell stack 2 through the second anode air inlet pipe 6. The anode air outlet channel of the second fuel cell stack 2 is connected to the second anode air outlet pipe 7.

[0061] A flow controller is installed on the first anode inlet pipe 4; a flow controller is installed on the first anode outlet pipe 5.

[0062] In this embodiment, the first fuel cell stack 1 and the second fuel cell stack 2 can be subjected to current loading respectively. Gas is introduced into the first fuel cell stack 1 through the first anode inlet pipe 4. After the gas participates in the reaction in the first fuel cell stack 1, the excess gas is discharged from the anode outlet channel of the first fuel cell stack 1. The discharged gas has a high water vapor content. In this embodiment, a water control device 3 is set between the first fuel cell stack 1 and the second fuel cell stack 2 to remove water from the discharged gas. This significantly reduces the water content of the gas introduced into the second fuel cell stack 2, thereby improving the gas utilization rate and significantly improving the power generation efficiency of the fuel cell system in this embodiment.

[0063] The first fuel cell stack 1 includes at least one fuel cell stack, and the second fuel cell stack 2 includes at least one fuel cell stack.

[0064] In this embodiment, the preferred ratio of the number of fuel cell stacks in the first fuel cell stack group 1 to the number of fuel cell stacks in the second fuel cell stack group 2 is (1-7):1. When this condition is met, the fuel cell system exhibits good robustness and can maintain the fuel cell system in the optimal thermal management mode. If the ratio of the number of fuel cell stacks in the first fuel cell stack group 1 to the number of fuel cell stacks in the second fuel cell stack group 2 is greater than 7:1, the temperature of the second fuel cell stack group 2 will be too high, resulting in a large temperature difference between the anode inlet channel and the anode outlet channel in the second fuel cell stack group 2, affecting the fuel cell stack life and power generation performance of the second fuel cell stack group 2. If the ratio of the number of fuel cell stacks in the first fuel cell stack group 1 to the number of fuel cell stacks in the second fuel cell stack group 2 is less than 1:1, the gas flow entering the anode of the second fuel cell stack group 2 after being heated in the first heat exchanger 32 and the water circulating in the system after being heated in the second heat exchanger 33 cannot reach a suitable temperature and require further heating treatment, reducing the efficiency of the fuel cell system.

[0065] In this embodiment, the first fuel cell stack group 1 has no fewer than two fuel cell stacks, and the oxidizing gas (such as air, oxygen, etc.) in each fuel cell stack is input into each fuel cell stack in parallel; the second fuel cell stack group 2 has no fewer than two fuel cell stacks, and the oxidizing gas (such as air, oxygen, etc.) in each fuel cell stack is input into each fuel cell stack in parallel.

[0066] Specifically, in the first fuel cell stack group 1, the anode air inlet channel of each fuel cell stack is connected in parallel to the first anode air inlet pipe 4, and the anode air outlet channel of each fuel cell stack is connected in parallel to the first anode air outlet pipe 5.

[0067] In the second fuel cell stack 2, the anode inlet channel of each fuel cell stack is connected in parallel to the second anode inlet pipe 6, and the anode outlet channel of each fuel cell stack is connected in parallel to the second anode outlet pipe 7.

[0068] The casing of the first fuel cell stack 1 has a cathode inlet pipe 8 or an air inlet on the cathode side, and a cathode outlet pipe 9 or a cathode air outlet on the cathode side. The casing of the second fuel cell stack 2 has a cathode inlet pipe 8 or a cathode air inlet on the cathode side, and a cathode outlet pipe 9 or a cathode air outlet on the cathode side. In this embodiment, oxidizing gas (such as air, oxygen, etc.) is input into each fuel cell stack in parallel, which can reduce the internal temperature difference between the first fuel cell stack 1 and the second fuel cell stack 2, thereby maintaining the thermal balance of the fuel cell system and effectively delaying the aging of the fuel cell system.

[0069] The fuel cell stacks in the first stack group 1 and the fuel cell stacks in the second stack group 2 generate current respectively, which can improve the power generation efficiency of the fuel cell system.

[0070] Example 2

[0071] The gas battery system provided in this embodiment is an improvement on the basis of embodiment 1. The content disclosed in embodiment 1 will not be described again, and the content disclosed in embodiment 1 also belongs to the content disclosed in this embodiment.

[0072] Please see Figure 2 In this embodiment, the water control device 3 is a water controller 31.

[0073] Specifically, the water controller 31 has a water tank, and the air inlet of the water controller 31 is located on the water tank. An air inlet pipe is installed inside the water tank. One end of the air inlet pipe is connected to the air inlet, and the other end of the air inlet pipe extends into the water at the bottom of the water tank. The air outlet of the water controller 31 is located at the top of the water tank, and the water outlet of the water controller 31 is located at the bottom of the water tank. The water outlet is connected to a first recovery pipe 34. The first recovery pipe 34 is used to connect to the water pipe of the fuel cell system, so that the discharged water can be recycled in the fuel cell system, which significantly improves the water utilization efficiency.

[0074] Specifically, a temperature controller is installed inside the water controller 31. The temperature controller is used to adjust the water temperature in the water tank of the water controller 31. The temperature controller can be any one of a resistance heater, an induction heater, an electric arc heater, or a medium heat exchanger.

[0075] This embodiment also provides a method for controlling the water-to-carbon ratio of a fuel cell. This method is implemented using the fuel cell system provided in this embodiment and specifically includes the following steps:

[0076] (1) Gas is introduced into the anode of the first fuel cell stack 1 (temperature is 550-650℃). After the gas reacts in the first fuel cell stack 1, the gas that does not participate in the reaction is discharged from the anode of the first fuel cell stack 1. The temperature of the discharged gas is 700-780℃. After sampling and testing, the water-to-carbon ratio of the discharged gas is in the range of (20-50):1.

[0077] (2) The discharged gas is introduced into the water of the water controller 31. During the condensation and dehydration process, the water temperature of the water controller 31 is controlled at 44-64℃. The treated gas is discharged from the gas outlet of the water controller 31. The temperature of the treated gas is 44-64℃. After sampling and testing, the water-to-carbon ratio of the discharged gas is in the range of (1.2-3.5):1.

[0078] (3) Input the treated gas into the anode of the second fuel cell stack 2.

[0079] Example 3

[0080] The gas battery system provided in this embodiment is an improvement on the basis of embodiment 1. The content disclosed in embodiment 1 will not be described again, and the content disclosed in embodiment 1 also belongs to the content disclosed in this embodiment.

[0081] Please see Figure 3 In this embodiment, the water control device 3 includes a water controller 31 and a first heat exchanger 32.

[0082] The anode outlet channel of the first fuel cell stack 1 is connected to the first medium inlet of the first heat exchanger 32 through the first anode outlet pipe 5. The first medium outlet of the first heat exchanger 32 is connected to the air inlet of the water controller 31 through a pipe. The air outlet of the water controller 31 is connected to the second medium inlet of the first heat exchanger 32 through a pipe. The second medium outlet of the first heat exchanger 32 is connected to the anode inlet channel of the second fuel cell stack 2 through the second anode inlet pipe 6.

[0083] Specifically, the water controller 31 has a water tank, and the air inlet of the water controller 31 is located on the water tank. An air inlet pipe is installed inside the water tank. One end of the air inlet pipe is connected to the air inlet, and the other end of the air inlet pipe extends into the water at the bottom of the water tank. The air outlet of the water controller 31 is located at the top of the water tank, and the water outlet of the water controller 31 is located at the bottom of the water tank. The water outlet is connected to a first recovery pipe 34. The first recovery pipe 34 is used to connect to the water pipe of the fuel cell system, so that the discharged water can be recycled in the fuel cell system, which significantly improves the water utilization efficiency.

[0084] A temperature controller is installed inside the water controller 31. The temperature controller is used to regulate the water temperature in the water tank of the water controller 31. The temperature controller can be any one of a resistance heater, an induction heater, an electric arc heater, or a medium heat exchanger. The temperature controller is preferably a medium heat exchanger, and the medium introduced into the medium heat exchanger includes any one or more of water, steam, oil, and ethylene glycol. The medium introduced into the medium heat exchanger is preferably water. The medium inlet of the medium heat exchanger is connected to the medium input pipe 36; a flow controller is installed on the medium input pipe 36.

[0085] The working principle of the fuel cell system in this embodiment is as follows:

[0086] The gas flow discharged from the anode outlet channel of the first fuel cell stack 1 is characterized by high temperature and high humidity. After flowing into the first heat exchanger 32 for heat exchange and cooling, the gas flows into the water controller 31 for water removal and cooling, and then returns to the first heat exchanger 32 for heat exchange and heating, thus achieving self-heating of the gas flow. In this embodiment, by setting up the first heat exchanger 32 and the water controller 31, the thermal energy of the discharged gas flow can be fully utilized, improving the anode gas utilization rate and power generation efficiency of the fuel cell system.

[0087] This embodiment also provides a method for controlling the water-to-carbon ratio of a fuel cell. This method is implemented using the fuel cell system provided in this embodiment and specifically includes the following steps:

[0088] (1) Gas is introduced into the anode of the first fuel cell stack 1 (temperature is 550-650℃). After the gas reacts in the first fuel cell stack 1, the gas that does not participate in the reaction is discharged from the anode of the first fuel cell stack 1. The temperature of the discharged gas is 700-780℃. After sampling and testing, the water-to-carbon ratio of the discharged gas is in the range of (20-50):1.

[0089] (2) The discharged gas is fed into the first heat exchanger 32 for heat exchange to obtain gas A1, the temperature of gas A1 is 70-100℃;

[0090] Gas A1 is introduced into the water of water controller 31 for condensation and dehydration. During the condensation and dehydration process, the water temperature of water controller 31 is controlled at 44-64℃ to obtain gas A2. The temperature of gas A2 is 44-64℃. After sampling and testing, the water-to-carbon ratio of the discharged gas A2 is in the range of (1.2-3.5):1.

[0091] Gas A2 is delivered to the first heat exchanger 32 for heat exchange to obtain processed gas with a temperature of 550-650℃.

[0092] (3) The treated gas is delivered to the anode of the second fuel cell stack 2.

[0093] Compared with Example 2, in this example, after the gas is condensed and dehydrated, it can return to the first heat exchanger 32 for heat exchange and heating. This allows the water-to-carbon ratio of the gas input to the second fuel cell stack 2 to be controlled within a suitable range, while also having a higher temperature. This results in a smaller temperature difference between the gas input to the first fuel cell stack 1 and the gas input to the second fuel cell stack 2, which is beneficial to improving the overall efficiency of the system.

[0094] Example 4

[0095] The gas-fired battery system provided in this embodiment is an improvement on embodiment 3. The difference between this embodiment and embodiment 3 is as follows:

[0096] Please see Figure 4In this embodiment, the water control device 3 includes a water controller 31, a first heat exchanger 32, and a second heat exchanger 33.

[0097] The anode outlet of the first fuel cell stack 1 is connected to the first medium inlet of the first heat exchanger 32 via the first anode outlet pipe 5. The first medium outlet of the first heat exchanger 32 is connected to the first medium inlet of the second heat exchanger 33 via a pipe. The first medium outlet of the second heat exchanger 33 is connected to the air inlet of the water controller 31 via a pipe. The air outlet of the water controller 31 is connected to the second medium inlet of the first heat exchanger 32 via a pipe. The water outlet of the water controller 31 is connected to the second medium inlet of the second heat exchanger 33 via a pipe. The second medium outlet of the first heat exchanger 32 is connected to the anode air inlet of the second fuel cell stack 2 via the second anode air inlet pipe 6. The second medium outlet of the second heat exchanger 33 is connected to the second recovery pipe 35.

[0098] A flow controller is installed on the pipe connected to the second medium inlet of the second heat exchanger 33.

[0099] The working principle of the fuel cell system in this embodiment is as follows:

[0100] The gas flow discharged from the anode outlet channel of the first fuel cell stack 1 is characterized by high temperature and high humidity. After flowing into the first heat exchanger 32 for heat exchange and cooling, the gas flows into the second heat exchanger 33 for further cooling. By controlling the water temperature in the water tank of the water controller 31 through a thermostat, the cooled gas flow can flow into the water controller 31 to remove water and further reduce the temperature of the gas flow. Then, it returns to the first heat exchanger 32 for heat exchange and heating, thus realizing the self-heating of the gas flow. The water in the water tank of the water controller 31 is introduced into the second heat exchanger 33 through a pipe to exchange heat with the gas flow. In this embodiment, through the arrangement of the first heat exchanger 32, the second heat exchanger 33, and the water controller 31, the thermal energy of the discharged gas flow can be fully utilized, improving the anode gas utilization rate and power generation efficiency of the fuel cell system.

[0101] This embodiment also provides a method for controlling the water-to-carbon ratio of a fuel cell. This method is implemented using the fuel cell system provided in this embodiment and specifically includes the following steps:

[0102] (1) Gas is introduced into the anode of the first fuel cell stack 1 (temperature is 550-650℃). After the gas reacts in the first fuel cell stack 1, the gas that does not participate in the reaction is discharged from the anode of the first fuel cell stack 1. The temperature of the discharged gas is 700-780℃. After sampling and testing, the water-to-carbon ratio of the discharged gas is in the range of (20-50):1.

[0103] (2) The discharged gas is fed into the first heat exchanger 32 for heat exchange to obtain gas B1, the temperature of gas B1 is 380~420℃;

[0104] Gas B1 is fed into the second heat exchanger 33 for heat exchange to obtain gas B2, the temperature of gas B2 being 70-100℃;

[0105] Gas B2 is introduced into the water in water controller 31 for condensation and dehydration to obtain gas B3. The temperature of gas B3 is 44-64℃. After sampling and testing, the water-to-carbon ratio of gas B3 is in the range of (1.2-3.5):1.

[0106] Gas B3 is delivered to the first heat exchanger 32 for heat exchange to obtain processed gas with a temperature of 550-650℃.

[0107] (3) The treated gas is delivered to the anode of the second fuel cell stack 2.

[0108] Compared with Example 3, in Example 4, the gas flow passes through the first heat exchanger 32 and the second heat exchanger 33 in sequence to cool down before entering the water controller 31 for condensation and dehydration, resulting in higher heat exchange efficiency.

[0109] It is understood that, in the above embodiments, the specifications of the first heat exchanger 32, the second heat exchanger 33, and the water controller 31 can be designed according to actual needs.

[0110] For example, the length, inner diameter, and outer diameter of the heat exchange tubes in the first heat exchanger 32 are designed so that the temperature of the gas at 700-780°C drops to 380-420°C after heat exchange in the first heat exchanger 32, and the temperature of the gas at 44-64°C rises to 550-650°C after heat exchange in the first heat exchanger 32.

[0111] For example, the length, inner diameter, and outer diameter of the heat exchange tubes in the second heat exchanger 33 are designed so that the temperature of the gas at 380-420°C drops to 70-100°C after heat exchange in the second heat exchanger 33.

[0112] For example, the volume of the water tank inside the water controller 31, the water volume, the length of the inlet pipe extending in the water, and the diameter of the inlet pipe are designed so that the gas at 700-780°C exchanges heat with the water in the inlet pipe, and the temperature of the gas discharged from the water controller 31 can be as low as 44-64°C.

[0113] In the description of this invention, it should be understood that the terms "upper," "lower," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0114] In the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connect," and "install," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can be a direct connection or an indirect connection through other components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for controlling the water-to-carbon ratio in a fuel cell, characterized in that, Includes the following steps: (1) Gas is introduced into the anode of the first fuel cell stack. After the gas reacts in the first fuel cell stack, the gas that has not participated in the reaction is discharged from the anode of the first fuel cell stack. (2) The exhaust gas is treated to remove water vapor. After the water removal treatment, the water-to-carbon ratio of the gas is (1.2~3.5):

1. (3) Input the treated gas into the anode of the second fuel cell stack; Step (1) also includes: inputting oxidizing gas into the first fuel cell stack and the second fuel cell stack in parallel; Step (2) specifically includes: The discharged gas is fed into the first heat exchanger for the first heat exchange to obtain gas B1, the temperature of which is 380~420℃. Gas B1 is fed into the second heat exchanger for a second heat exchange to obtain gas B2, the temperature of gas B2 being 70~100℃; Gas B2 is fed into a water controller for condensation and dehydration to remove some water vapor, yielding gas B3. The temperature of gas B3 is 44~64℃, and the water-to-carbon ratio of gas B3 is (1.2~3.5):

1. The gas B3 is fed into the first heat exchanger for heat exchange to obtain processed gas with a temperature of 550~650℃.

2. The water-to-carbon ratio control method for a fuel cell as described in claim 1, characterized in that, The water-to-carbon ratio control method is implemented through a fuel cell system, which includes a first stack, a second stack, and a water control device. The anode inlet channel of the first stack is connected to a first anode inlet pipe, the anode outlet channel of the first stack is connected to the inlet of the water control device, the outlet of the water control device is connected to the anode inlet channel of the second stack, and the anode outlet channel of the second stack is connected to a second anode outlet pipe. The first fuel cell stack has a cathode inlet pipe or inlet on the cathode side of its housing, and a cathode outlet pipe or inlet on the cathode side of its housing; the second fuel cell stack has a cathode inlet pipe or inlet on the cathode side of its housing, and a cathode outlet pipe or inlet on the cathode side of its housing; the cathode inlet pipes of the first fuel cell stack and the second fuel cell stack are connected in parallel. The water control device includes a first heat exchanger and a water controller. The anode outlet channel of the first fuel cell stack is connected to the first medium inlet of the first heat exchanger through a pipe. The first medium outlet of the first heat exchanger is connected to the air inlet of the water controller through a pipe. The air outlet of the water controller is connected to the second medium inlet of the first heat exchanger through a pipe. The second medium outlet of the first heat exchanger is connected to the anode inlet channel of the second fuel cell stack. The water control device further includes a second heat exchanger, which is disposed on the pipeline between the first heat exchanger and the water controller. The first medium outlet of the first heat exchanger is connected to the first medium inlet of the second heat exchanger through a pipeline, and the first medium outlet of the second heat exchanger is connected to the air inlet of the water controller through a pipeline.

3. The water-to-carbon ratio control method for a fuel cell as described in claim 2, characterized in that, The outlet of the water controller is connected to the second medium inlet of the second heat exchanger via a pipe.

4. The method for controlling the water-to-carbon ratio of a fuel cell as described in claim 2, characterized in that, The ratio of the number of fuel cells in the first fuel cell stack group to the number of fuel cells in the second fuel cell stack group is (1~7):1.

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