Fuel cell system

Abstract

The invention discloses a fuel cell system. The fuel cell system comprises an electric pile, an air input unit, a fuel input unit, an air preheater, a reforming cooler and a condenser, the electric pile comprises an anode inlet, an anode outlet, a cathode inlet and a cathode outlet; the air preheater is respectively connected with the air input unit, the condenser and the cathode inlet; the reforming cooler is respectively connected with the anode inlet, the fuel input unit, the condenser and the anode outlet; and the condenser is also connected with the air input unit. According to the technical scheme, the condenser, the air preheater and the reforming cooler are arranged in the fuel cell system for heat management of the fuel cell system, so that the same gas is utilized for heat exchange at high temperature, and the reliability problem caused by cross leakage is avoided; and meanwhile, heat exchange of different gases is carried out at a lower temperature, so that the problem of cross leakage of the gases is solved, and the reliability of the heat exchange process is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and particularly to a fuel cell system. Background Art

[0002] Currently, most of the thermal management in a solid oxide fuel cell system is achieved by heat exchange between air and high-temperature exhaust gas to recover the energy in the system. However, the fuel cell system operates at a high temperature, and there is a risk of leakage in the heat exchanger at high temperatures, increasing the operating risk of the system. Summary of the Invention

[0003] The present invention provides a fuel cell system to solve the problem of poor reliability in the heat exchange process of the existing fuel system and the risk of leakage.

[0004] A fuel cell system according to the present invention includes: a stack, an air input unit, a fuel input unit, an air preheater, a reforming cooler, and a condenser;

[0005] The stack includes an anode inlet, an anode outlet, a cathode inlet, and a cathode outlet;

[0006] The air preheater is respectively connected to the air input unit, the condenser, and the cathode inlet, and is used to receive the air from the air input unit and the air from the condenser, preheat them, and then input them into the cathode inlet;

[0007] The reforming cooler is respectively connected to the anode inlet, the fuel input unit, the condenser, and the anode outlet, and is used to receive the fuel from the fuel input unit and the anode exhaust gas from the anode outlet, reform and preheat them, and then input them into the anode inlet. It is also used to input the heat-exchanged anode exhaust gas into the condenser;

[0008] The condenser is also connected to the air input unit, and is used to receive the air from the air input unit and the anode exhaust gas from the reforming cooler, exchange heat to output condensed water and the heat-exchanged anode exhaust gas, and is also used to input the heat-exchanged air into the air preheater.

[0009] Optionally, the fuel cell system further includes a burner; the burner is respectively connected to the cathode outlet and the reforming cooler;

[0010] The burner is used to receive the anode exhaust gas after heat exchange in the reforming cooler and the cathode exhaust gas output from the cathode outlet, mix and burn them, and then output combustion gas.

[0011] Optionally, the air preheater is connected to the burner, and is used to receive the combustion gas, preheat the air using the combustion gas, and is also used to discharge the heat-exchanged combustion gas.

[0012] Optionally, the fuel cell system further includes a fuel preheater;

[0013] The fuel preheater is respectively connected to the reforming cooler and the condenser, and is used to receive the anode tail gas input from the condenser and preheat the anode tail gas and input it into the reforming cooler;

[0014] The reforming cooler is used to receive the fuel from the fuel input unit, the anode tail gas from the anode outlet and the anode tail gas from the fuel preheater, and reform and preheat them and then input them into the anode inlet.

[0015] Optionally, the fuel cell system further includes a burner; the burner is respectively connected to the cathode outlet, the reforming cooler and the air preheater;

[0016] The air preheater is also connected to the fuel preheater, and is used to receive the combustion gas after heat exchange by the burner and use the combustion gas to preheat the air, and is also used to input the combustion gas after heat exchange into the fuel preheater;

[0017] The fuel preheater is used to preheat the anode tail gas by using the combustion gas.

[0018] Optionally, a circulation pump is included in the connecting pipeline between the condenser and the fuel preheater;

[0019] The circulation pump is used to control the amount of the anode tail gas input from the reforming cooler to the condenser.

[0020] Optionally, a first control valve is included in the connecting pipeline between the air input unit and the condenser;

[0021] The first control valve is used to control the amount of the air input from the air input unit to the condenser.

[0022] Optionally, a second control valve is included in the connecting pipeline between the air input unit and the air preheater;

[0023] The second control valve is used to control the amount of the air input from the air input unit to the air preheater.

[0024] Optionally, the fuel input unit includes a fuel tank and a booster pump;

[0025] The booster pump is arranged on the connecting pipeline between the fuel tank and the reforming cooler, and is used to control the amount of the fuel input from the fuel tank to the reforming cooler.

[0026] Optionally, the air input unit includes a fan, which is used to control the amount of the air entering the air preheater and the condenser by controlling the rotation speed.

[0027] The technical solution of the embodiment of the present invention performs thermal management on the fuel cell system by arranging a condenser, an air preheater and a reforming cooler in the fuel cell system, so that heat exchange is carried out by using the same kind of gas at a high temperature, avoiding the reliability problem caused by cross leakage; at the same time, heat exchange between different gases is carried out at a relatively low temperature, eliminating the problem of gas cross leakage and improving the reliability of the heat exchange process.

[0028] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Brief Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0030] Figure 1 is a schematic connection diagram of the first fuel cell system provided according to an embodiment of the present invention;

[0031] Figure 2 is a diagram showing the flow relationship of carbon elements in the fuel cell stack provided according to an embodiment of the present invention;

[0032] Figure 3 is a diagram showing the flow relationship of oxygen elements in the fuel cell stack provided according to an embodiment of the present invention;

[0033] Figure 4 is a diagram showing the flow relationship of hydrogen elements in the fuel cell stack provided according to an embodiment of the present invention. Detailed Embodiments

[0034] In order to enable those skilled in the art to better understand the solutions of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0035] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here.

[0036] Figure 1 is a schematic connection diagram of the first fuel cell system provided according to an embodiment of the present invention. As Figure 1As shown, the fuel cell system includes: a fuel cell stack 1, an air input unit 2, a fuel input unit 3, an air preheater 4, a reforming cooler 5, and a condenser 6;

[0037] The fuel cell stack 1 includes an anode inlet 11, an anode outlet 12, a cathode inlet 13, and a cathode outlet 14;

[0038] The air preheater 4 is respectively connected to the air input unit 2, the condenser 6, and the cathode inlet 13, and is used to receive the air from the air input unit 2 and the air from the condenser 6, preheat them, and then input them into the cathode inlet 13;

[0039] The reforming cooler 5 is respectively connected to the anode inlet 11, the fuel input unit 3, the condenser 6, and the anode outlet 12, and is used to receive the fuel from the fuel input unit 3 and the anode exhaust gas from the anode outlet 12, reform and preheat them, and then input them into the anode inlet 11. It is also used to input the heat-exchanged anode exhaust gas into the condenser 6;

[0040] The condenser 6 is also connected to the air input unit 2, and is used to receive the air from the air input unit 2 and the anode exhaust gas from the reforming cooler 5, exchange heat, output condensed water and the heat-exchanged anode exhaust gas, and is also used to input the heat-exchanged air into the air preheater 4.

[0041] Among them, the anode inlet 11 of the fuel cell stack 1 can be used to input high-temperature fuel gas, and the cathode inlet 13 can be used to input high-temperature air. The fuel gas entering the fuel cell stack 1 from the anode inlet 11 undergoes an electrochemical reaction with the oxygen in the air entering the fuel cell stack 1 from the cathode, thereby converting chemical energy into electrical energy, and then realizing the power generation of the fuel cell.

[0042] Among them, in order to improve the efficiency of the fuel cell system, thermal management is often performed on the fuel cell system. In the embodiments of the present invention, an air preheater 4, a reforming cooler 5, and a condenser 6 are provided. The air preheater 4 is disposed on the connecting pipeline between the air input unit 2 and the cathode inlet 13, and can be used to preheat the air input by the air input unit 2 and input the heated air into the cathode inlet 13; the reforming cooler 5 can be used to carry out a reforming reaction. The reforming cooler 5 is respectively connected to the anode inlet 11, the fuel input unit 3, the condenser 6, and the anode outlet 12, and receives the fuel gas input by the combustion input unit and the anode exhaust gas output from the anode outlet 12. Since the temperature of the anode exhaust gas after the reaction is high, the anode exhaust gas can be used to preheat the fuel gas, and the heated fuel gas is input into the anode inlet 11, and the temperature of the anode exhaust gas after heat exchange decreases and is output to the condenser 6. The condenser 6 is respectively connected to the air input unit 2, the air preheater 4, and the reforming cooler 5. The condenser 6 receives the air input by the air input unit 2. Since the air is unheated air, the air can be used to cool the anode exhaust gas input by the reforming cooler 5. The cooled anode exhaust gas generates condensed water and the cooled anode exhaust gas and are respectively output from the condenser 6, and the air after heat exchange is continuously input into the air preheater 4.

[0043] Exemplarily, the air preheater 4 is provided with a first inlet a1 and a first outlet b1. The first inlet a1 is communicated with the air input unit 2, and the first outlet b1 is communicated with the cathode inlet 13. The condenser 6 includes a second inlet a2, a third inlet a3, a second outlet b2, a third outlet b3, and a fourth outlet b4. The reforming cooler 5 includes a fourth inlet a4, a fifth inlet a5, a fifth outlet b5, and a sixth outlet b6. The second inlet a2 is communicated with the air input unit 2, the second outlet b2 is communicated with the pipeline between the air input unit 2 and the first inlet a1, the third inlet a3 is communicated with the sixth outlet b6, the fourth inlet a4 is communicated with the fuel input unit 3, the fifth outlet b5 is communicated with the anode inlet 11, and the fifth inlet a5 is communicated with the anode outlet 12. The third outlet b3 can be used to output condensed water, and the fourth outlet b4 can be used to output the anode exhaust gas after heat exchange and cooling.

[0044] It can be understood that in the prior art, the heat management link of the fuel cell system mostly completes the energy recovery in the system by exchanging heat between air and high-temperature exhaust gas. However, due to the high operating temperature of the fuel cell system, the heat exchanger will experience a decline in reliability and a risk of leakage when exchanging heat at high temperature for a long time. In the embodiment of the present invention, the reforming cooler 5 is arranged to exchange heat between the anode exhaust gas and the fuel gas. This heat exchange method is heat exchange between the same kind of gas, effectively avoiding problems such as explosion caused by cross leakage. In addition, in the embodiment of the present invention, the condenser 6 is arranged to cool the anode exhaust gas with air. Although this step is heat exchange between different gases, since the input air is at normal temperature and pressure, the heat exchange temperature is relatively low, and the seal under working conditions can be well ensured in the existing process, avoiding leakage and ensuring the reliability of the heat exchange process at the same time.

[0045] In some embodiments, the fuel input unit 3 includes a fuel tank 31 and a booster pump 32; the booster pump 32 is arranged on the connecting pipeline between the fuel tank 31 and the reforming cooler 5, and is used to control the fuel quantity input from the fuel tank 31 to the reforming cooler 5. Among them, the fuel tank 31 can be used to store fuel gas. By arranging the booster pump 32 on the connecting pipeline between the fuel tank 31 and the reforming cooler 5, the fuel quantity input from the fuel tank 31 to the reforming cooler 5 can be controlled by controlling the booster pump 32, thereby changing the efficiency of the fuel cell system.

[0046] In some embodiments, the air input unit 2 includes a fan 20, which is used to control the air quantity entering the air preheater 4 and the condenser 6 by controlling the rotation speed. By arranging the fan 20 in the fuel cell system, the air quantity entering the air preheater 4 and the condenser 6 is controlled by controlling the rotation speed of the fan 20, thereby changing the efficiency of the fuel cell system.

[0047] The technical solution of the embodiment of the present invention performs heat management of the fuel cell system by arranging a condenser, an air preheater and a reforming cooler in the fuel cell system, enabling heat exchange with the same kind of gas at high temperature, avoiding reliability problems caused by cross leakage; at the same time, heat exchange between different gases is carried out at a lower temperature, eliminating the problem of gas cross leakage and improving the reliability of the heat exchange process.

[0048] Optionally, continue to refer to Figure 1 As shown, the fuel cell system further includes a burner 7; the burner 7 is respectively connected to the cathode outlet 14 and the reforming cooler 5;

[0049] The burner 7 is used to receive the anode exhaust gas after heat exchange by the reforming cooler 5 and the cathode exhaust gas output from the cathode outlet 14, and mix and burn them to output combustion gas.

[0050] Among them, the burner 7 can be used to mix and burn the cathode exhaust gas and the anode exhaust gas, remove the harmful gases in the cathode exhaust gas and the anode exhaust gas, and ensure the operation safety of the fuel cell system. Therefore, the burner 7 is respectively connected to the cathode outlet 14 and the reforming cooler 5, receives the anode exhaust gas after heat exchange by the reforming cooler 5 and the cathode exhaust gas at the cathode outlet 14, and outputs the combustion gas after mixing and burning to remove the harmful gases, ensuring the operation safety of the fuel cell system.

[0051] Exemplarily, the burner 7 includes a sixth inlet a6 and a seventh inlet a7. The sixth inlet a6 communicates with the sixth outlet b6, and the seventh inlet a7 communicates with the cathode outlet 14, so that the anode exhaust gas and the cathode exhaust gas enter the burner 7. It can be understood that since the third inlet a3 also communicates with the sixth outlet b6, part of the anode exhaust gas is condensed by the condenser 6 and part is burned by the burner 7.

[0052] The technical solution of the embodiment of the present invention, by arranging a burner in the fuel cell system, the burner is respectively connected to the cathode outlet and the reforming cooler, ensuring that the anode exhaust gas after heat exchange and the cathode exhaust gas at the cathode outlet are burned to remove harmful gases, and ensuring the operation safety of the fuel cell system.

[0053] Optionally, continue to refer to Figure 1 As shown, the air preheater 4 is connected to the burner 7, which is used to receive the combustion gas and preheat the air by using the combustion gas, and is also used to discharge the heat-exchanged combustion gas.

[0054] Among them, since the combustion gas output by the burner 7 is harmless and at a relatively high temperature, discharging it from the fuel cell system is not conducive to improving the system efficiency. Therefore, connecting the air preheater 4 to the burner 7 can use the heat of the combustion gas to preheat the air in the air preheater 4 and discharge the heat-exchanged combustion gas.

[0055] Exemplarily, the air preheater 4 further includes an eighth inlet a8 and a seventh outlet b7. The eighth inlet a8 is connected to the burner 7, receives the combustion gas output by the burner 7, exchanges heat with the air, and is output through the seventh outlet b7 of the air preheater 4.

[0056] It can be understood that in the embodiment of the present invention, the energy carried by the fuel gas discharged from the burner 7 is recovered through heat exchange by the air preheater 4, reducing heat loss and improving the efficiency of the fuel cell system. In addition, the heat exchange gas in the air preheater 4 is also the same gas, that is, the combustion gas and the air, which can also effectively avoid the explosion problem caused by cross leakage.

[0057] In the technical solution of the embodiment of the present invention, by connecting the air preheater to the burner, the combustion gas discharged from the burner can enter the air preheater. Through the heat exchange between the combustion gas and the air, the high-temperature gas is heated, reducing heat loss, improving the efficiency of the fuel cell system, and effectively avoiding the explosion problem caused by cross-leakage.

[0058] Optionally, continue to refer to Figure 1 As shown, the fuel cell system further includes a fuel preheater 8;

[0059] The fuel preheater 8 is respectively connected to the reforming cooler 5 and the condenser 6, and is used to receive the anode tail gas input from the condenser 6 and preheat the anode tail gas and input it into the reforming cooler 5;

[0060] The reforming cooler 5 is used to receive the fuel from the fuel input unit 3, the anode tail gas from the anode outlet 12 and the anode tail gas from the fuel preheater 8, and reform and preheat them and then input them into the anode inlet 11.

[0061] Among them, a fuel preheater 8 can also be provided in the fuel cell system. The fuel preheater 8 can be used to preheat the anode tail gas and input it into the reforming cooler 5, and then a certain amount of anode tail gas is introduced into the fuel gas so that the mixed gas meets a certain oxygen-carbon ratio to prevent carbon deposition.

[0062] Exemplarily, the fuel preheater 8 includes an eighth outlet b8 and a ninth inlet a9. The eighth outlet b8 can be connected to the fourth inlet a4 of the reforming cooler 5, and the ninth inlet a9 is connected to the fourth outlet b4 of the condenser 6 to receive the cooled anode tail gas from the condenser 6 and preheat it and input it into the reforming cooler 5.

[0063] It can be understood that the fuel preheater 8 further recycles the cooled anode tail gas in the condenser 6 to the anode, improving the efficiency of the fuel cell system.

[0064] In the technical solution of the embodiment of the present invention, by providing a fuel preheater and connecting the fuel preheater to the reforming cooler and the condenser respectively, the purpose of further utilizing the anode tail gas is achieved, and the efficiency of the fuel cell system is improved.

[0065] Optionally, continue to refer to Figure 1 As shown, the fuel cell system further includes a burner 7; the burner 7 is respectively connected to the cathode outlet 14, the reforming cooler 5 and the air preheater 4;

[0066] The air preheater 4 is also connected to the fuel preheater 8, and is used to receive the combustion gas after heat exchange by the burner 7 and use the combustion gas to preheat the air, and is also used to input the combustion gas after heat exchange into the fuel preheater 8;

[0067] The fuel preheater 8 is used to preheat the anode tail gas with the combustion gas.

[0068] Among them, on the basis that the burner 7 is provided, the air preheater 4 is further connected to the fuel preheater 8, so that the combustion gas after heat exchange with air is further input into the fuel preheater 8 to further preheat the anode tail gas, and the preheated anode tail gas is input into the reforming cooler 5.

[0069] Exemplarily, the fuel preheater 8 further includes a tenth inlet a10, and the air preheater 4 further includes a seventh outlet b7. The tenth inlet a10 and the seventh outlet b7 are communicated, so that the combustion gas after heat exchange can further enter the fuel preheater 8 to preheat the anode tail gas.

[0070] It can be understood that the temperature of the combustion gas discharged from the burner 7 is relatively high and will carry a lot of heat. In order to ensure the efficiency of the system, the combustion gas is further heat-exchanged in the combustion preheater after heat exchange with air, and two-stage energy recovery is carried out to make full use of the heat of the combustion gas, reduce heat loss and improve the system efficiency. In addition, since the fuel gas has experienced heat exchange once in the heat exchange process in the fuel preheater 8, this heat exchange process is a low-temperature heat exchange process, so that even if the heat exchange in the gas preheater is between different gases, the temperature is relatively low, and the seal under working conditions can be well ensured and leakage can be avoided under the existing process.

[0071] It can be understood that inputting the anode tail gas into the reforming cooler 5 after a certain degree of preheating can help preheat the fuel gas by the anode tail gas input from the anode outlet 12 and improve the preheating efficiency of the fuel gas.

[0072] The technical solution of the embodiment of the present invention, by connecting the air preheater to the fuel preheater in the fuel cell system, recovers two-stage energy of the fuel gas, makes full use of the heat of the combustion gas, reduces heat loss and improves the system efficiency. At the same time, heat exchange under low-temperature conditions can reduce the risk of gas leakage and also improve the preheating efficiency of the fuel gas.

[0073] Optionally, continue to refer to Figure 1 As shown, a circulation pump 9 is included on the connecting pipeline between the condenser 6 and the fuel preheater 8;

[0074] The circulation pump 9 is used to control the amount of the anode tail gas input from the reforming cooler 5 to the condenser 6.

[0075] Among them, the circulation pump 9 is arranged on the connecting pipeline between the condenser 6 and the fuel preheater 8, and the flow rate in this pipeline can be controlled by controlling the circulation pump 9. Since the anode tail gas after heat exchange output from the self-reforming cooler 5 is input into the burner 7 for combustion on the one hand and input into the condenser 6 for condensation on the other hand, setting the circulation pump 9 can change the amount of anode tail gas entering the condenser 6. In some embodiments, the fuel cell system further includes a burner 7, and then the circulation pump 9 can change the ratio of the anode tail gas entering the condenser 6 and the burner 7.

[0076] It can be understood that using the condenser 6 to exchange heat and cool the anode tail gas can avoid damage to the circulation pump 9 caused by high-temperature anode tail gas, improve the reliability of system operation, and at the same time achieve the purpose of condensing and separating out condensed water.

[0077] In the technical solution of the embodiment of the present invention, by setting a circulation pump on the connecting pipeline between the condenser and the fuel preheater, and controlling the amount of anode tail gas input from the reforming cooler to the condenser by controlling the circulation pump, the normal operation of the fuel cell system is ensured.

[0078] Optionally, continue to refer to Figure 1 As shown, a first control valve K1 is included on the connecting pipeline between the air input unit 2 and the condenser 6;

[0079] The first control valve K1 is used to control the amount of air input from the air input unit 2 to the condenser 6.

[0080] Among them, the first control valve K1 is arranged on the connecting pipeline between the air input unit 2 and the condenser 6, and can control the amount of air input from the air input unit 2 to the condenser 6. Since the change in the gas composition of H 2 、H 2 O in the gas components circulating to the inlet of the fuel cell stack 1 leads to an increase in the oxygen-carbon ratio, and re-entering the fuel cell stack 1 will cause the operating voltage to become lower, resulting in attenuation and damage of the fuel cell stack 1. Therefore, the embodiment of the present invention adopts the method of supplementing fuel and removing condensed water in the circulating fuel to appropriately adjust the inlet components, relieve the working pressure of the fuel cell stack 1, and the method of removing condensed water is to control the amount of air entering the condenser 6 by controlling the first control valve K1, adjust the temperature of the tail gas outlet of the condenser 6 to control the flow rate of the separated water, and then control the flow rate of the discharged water, achieving the function of adjusting the oxygen-carbon ratio of the system while reducing the parasitic power consumption and heat loss of the system. The specific principle and calculation process are as follows:

[0081] The first step is to calculate the flow rate of the C element first, Figure 2 It is a flow rate relationship diagram of carbon elements in the fuel cell stack provided by the embodiment of the present invention. Combining Figure 1 and Figure 2 As shown, the flow rate of the C element in the fuel cell stack 1 includes the total flow rate C of the fuel cell system mfc, the flow rate C entering the stack 1 in , the flow rate C output from the stack 1 out and the flow rate C circulating in the stack 1 out *r. The flow rate of each C element satisfies C in = C out and C in = C mfc + C out *r, from which it can be obtained that

[0082] In the second step, the flow rate of the O element is calculated. Figure 3 It is a flow rate relationship diagram of oxygen element in the stack provided by the embodiment of the present invention. Combining Figure 1 and Figure 3 as shown, the flow rate of the O element in the stack 1 includes the total flow rate O mfc entering the fuel cell system, the flow rate O in entering the stack 1, the flow rate O out output from the stack 1, the flow rate O out *r circulating in the stack 1, the flow rate of the condensed water precipitated and O 电堆1 . The flow rate of each O element satisfies O out = O in + O 电堆1 , O in = O mfc + C out *r - the flow rate of the condensed water and the flow rate in the stack 1 From which it can be obtained that

[0083] When the fuel cell system operates in a steady state, no additional water needs to enter the system. Therefore, at this time, O mfc = 0, and the oxygen-carbon ratio entering the stack 1 is obtained as:

[0084] where r is the circulation rate and F is the Faraday constant.

[0085] According to the above formula, it can be known that the actual oxygen-carbon ratio during steady-state operation only depends on the current, the circulation rate r, the total flow rate C mfc entering the fuel cell system and the condensed water flow rate.

[0086] In the third step, the total flow rate C mfc entering the fuel cell system is calculated. Figure 4 It is a flow rate relationship diagram of hydrogen element in the stack provided by the embodiment of the present invention. Combining Figure 1 and Figure 4 as shown, it can be obtained through the current, the circulation rate and the fuel utilization rate of the stack 1. The flow rate of the H element in the stack 1 includes: the flow rate H of the H element in the fuel gas fuel, the flow rate H entering the stack 1 in , the flow rate H output from the stack 1 out , the flow rate H circulating in the stack 1 out *r and the flow rate H in the stack 1 电堆1 . The flow rate of each H element satisfies H in = H out + H fuel and H out = H in (1 - U fuel ) = H in - H 电堆1 , from which we can obtain That is, the total flow rate C required to be introduced into the fuel cell system mfc is Among them, H eq is the hydrogen equivalent of the fuel gas, and U fuel is the fuel utilization rate.

[0087] According to the above calculations, it can be obtained that the oxygen-carbon ratio of the stack 1 can be calculated through the current, circulation rate, and fuel utilization rate of the stack 1. Therefore, it can be considered that there is a corresponding relationship between the condensate flow rate and the actual oxygen-carbon ratio at the inlet of the stack 1. Due to the large thermal inertia of the thermal components, the regulation of the condensate flow rate has a larger time constant compared to the regulation of other variables. Therefore, it is considered that other physical quantities have been regulated in place when regulating the condensate. Therefore, the calculation of the condensate flow rate can first calculate the actual oxygen-carbon ratio according to the current, circulation rate, and fuel utilization rate of the stack 1. The actual oxygen-carbon ratio is combined with the oxygen-carbon ratio demand value of the fuel cell system to determine the oxygen-carbon ratio difference. The oxygen-carbon ratio difference is multiplied by the total flow rate C introduced into the fuel cell system mfc to obtain the condensate flow rate.

[0088] Since usually the temperature detection value has higher sensitivity and accuracy than the flow rate monitoring value, the regulation of the oxygen-carbon ratio in the fuel cell system can be completed by means of the temperature sensor set in the condenser 6 in combination with the temperature and saturated humidity comparison table. Exemplarily, the first temperature sensor is set at the inlet of the condenser 6, and the second temperature sensor is set at the outlet of the condenser 6. First, according to the inlet temperature T in of the first temperature sensor in combination with the temperature and saturated humidity comparison table, look up the table to obtain the inlet humidity RH1 of the condenser 6. Then, according to the inlet flow rate of the condenser 6, the condensate demand, the target humidity RH2 at the outlet of the condenser 6 can be obtained. The inlet flow rate Q1 of the condenser 6, the condensate demand Q0, the inlet humidity RH1 of the condenser 6, and the target humidity RH2 at the outlet of the condenser 6 satisfy Combined with the temperature and saturated humidity comparison table of the target humidity RH2 at the outlet of the condenser 6, the required target outlet temperature T out需求 is obtained. out需求Combined with the actual outlet temperature T out The temperature demand difference can be calculated and converted into the flow demand difference dm by using the first proportional-integral controller 需求 , the flow demand difference dm 需求 Combined with the actual flow difference, the flow difference is calculated, and then the opening of the first control valve K1 is controlled by means of the second proportional-integral controller, so as to achieve more accurate and rapid regulation, realize the precise control of the oxygen-carbon ratio of the fuel cell stack 1, and have high anti-interference ability, thereby better improving the performance of the system.

[0089] It can be understood that in the prior art, the oxygen-carbon ratio entering the fuel cell stack 1 is completed through three links: condensation and water removal, supplementary combustion, and water replenishment. During this period, too much energy will be carried away by the condensed water, and the phase change of the replenished water will consume extra system heat, which will further reduce the energy utilization efficiency of the system, and the operation of the water pump will also further reduce the energy efficiency of the system. Therefore, the technical solution of the embodiment of the present invention, by setting the first control valve K1, adjusts the oxygen-carbon ratio in real time according to the amount of condensed water, improves the power of the fuel cell stack 1; at the same time, avoids the energy waste caused by too much condensed water, improves the system efficiency; reduces the use of components such as water pumps, and reduces the parasitic power consumption. At the same time, by means of the first proportional-integral controller and the second proportional-integral controller, a double closed-loop control method for the temperature outer loop and the flow inner loop of the condenser 6 is realized, which has the advantages of high adjustment accuracy, fast response speed and strong anti-interference ability.

[0090] In some embodiments, the connecting pipeline between the air input unit 2 and the air preheater 4 includes a second control valve K2; the second control valve K2 is used to control the amount of air input from the air input unit 2 to the air preheater 4. By setting the second control valve K2, the amount of air entering the air preheater 4 can be further controlled to ensure the normal operation of the fuel cell system.

[0091] The technical solution of the embodiment of the present invention performs thermal management of the fuel cell system by setting a condenser, an air preheater and a reforming cooler in the fuel cell system, so that heat exchange is carried out using the same gas at high temperature, avoiding the reliability problem caused by cross leakage; at the same time, heat exchange between different gases is carried out at a lower temperature, eliminating the problem of gas cross leakage and improving the reliability of the heat exchange process.

[0092] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A fuel cell system, characterized in that: include: Fuel stack, air input unit, fuel input unit, air preheater, reformer cooler and condenser; The battery stack includes an anode inlet, an anode outlet, a cathode inlet and a cathode outlet; The air preheater is connected to the air input unit, the condenser and the cathode inlet respectively, and is used to receive the air from the air input unit and the air from the condenser and preheat the air before inputting it into the cathode inlet; The reforming cooler is connected to the anode inlet, the fuel input unit, the condenser and the anode outlet respectively, and is used to receive the fuel from the fuel input unit and the anode tail gas from the anode outlet and input them to the anode inlet after reforming and preheating, and is also used to input the anode tail gas after heat exchange to the condenser; The condenser is also connected to the air input unit, and is used to receive the air from the air input unit and the anode tail gas from the reforming cooler, and to output condensed water and the anode tail gas after heat exchange, and is also used to input the air after heat exchange into the air preheater.

2. The fuel cell system according to claim 1, characterized in that: The fuel cell system further comprises a burner; the burner is respectively connected to the cathode outlet and the reforming cooler; The burner is used to receive the anode tail gas after heat exchange in the reforming cooler and the cathode tail gas output from the cathode outlet, and output combustion gas after mixing and burning.

3. The fuel cell system according to claim 2, characterized in that: The air preheater is connected to the burner, and is used to receive the combustion gas and preheat the air using the combustion gas, and is also used to discharge the combustion gas after heat exchange.

4. The fuel cell system according to claim 1, characterized in that: The fuel cell system also includes a fuel preheater; The fuel preheater is connected to the reforming cooler and the condenser respectively, and is used to receive the anode tail gas input by the condenser and preheat the anode tail gas to be input into the reforming cooler; The reforming cooler is used to receive the fuel from the fuel input unit, the anode tail gas from the anode outlet, and the anode tail gas from the fuel preheater, and input the fuel to the anode inlet after reforming and preheating.

5. The fuel cell system according to claim 4, characterized in that: The fuel cell system further comprises a burner; the burner is respectively connected to the cathode outlet, the reforming cooler and the air preheater; The air preheater is also connected to the fuel preheater, and is used to receive the combustion gas after heat exchange in the burner and use the combustion gas to preheat the air, and is also used to input the combustion gas after heat exchange into the fuel preheater; The fuel preheater is used to preheat the anode tail gas using the combustion gas.

6. The fuel cell system according to claim 4, characterized in that: The connecting pipeline between the condenser and the fuel preheater includes a circulating pump; The circulation pump is used to control the amount of the anode tail gas input from the reforming cooler to the condenser.

7. The fuel cell system according to claim 1, characterized in that: The connecting pipeline between the air input unit and the condenser includes a first control valve; The first control valve is used to control the amount of the air input from the air input unit to the condenser.

8. The fuel cell system according to claim 1, characterized in that: The connecting pipeline between the air input unit and the air preheater includes a second control valve; The second control valve is used to control the amount of the air input from the air input unit to the air preheater.

9. The fuel cell system according to claim 1, characterized in that: The fuel input unit includes a fuel tank and a boost pump; The boost pump is disposed on a connecting pipeline between the fuel tank and the reforming cooler, and is used to control the amount of fuel input from the fuel tank to the reforming cooler.

10. The fuel cell system according to claim 1, characterized in that: The air input unit comprises a fan, which is used to control the amount of air entering the air preheater and the condenser by controlling the rotation speed.

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