Fuel cell system

Abstract

To provide a fuel cell system.SOLUTION: A fuel cell system includes a fuel cell 1 having an anode input terminal 11, a cathode input terminal 12, an anode output terminal 13, and a cathode output terminal 14, a selective separator 2 having a supply terminal 21, a hydrogen discharge terminal 22, and a residual air discharge terminal 23, a hydrogen pump 3, a purge valve 4, and a water trap 5. In this manner, the hydrogen separation efficiency is increased, and the hydrogen concentration in the exhaust gas is effectively reduced to less than 4 vol%.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a fuel cell system, and more particularly to a fuel cell system capable of improving the utilization rate of mixed fuel.

Background Art

[0002] Fuel cells are one of the currently widely applied energy sources, but conventional fuel cells have a lot of hydrogen waste and low hydrogen utilization rate. Also, when the exhaust gas concentration exceeds the standard value and does not meet the standard for discharging into the atmosphere, there is a danger.

[0003] Conventional patent documents, for example, Patent Document 1 discloses a "fuel cell system for improving hydrogen utilization rate". The fuel cell system is connected to a stack and includes a push-in pipeline and a push-out pipeline. In the push-out pipeline, a gas-liquid separator, an exhaust control valve, a pressure sensor, a hydrogen membrane separator, and a reflux control valve are installed, and the reflux control valve controls the gas to flow into the push-in pipeline. A controllable bypass pipeline is further installed between the gas-liquid separator and the push-in pipeline. The hydrogen membrane separator separates the hydrogen discharged during the nitrogen discharge process, and the reflux control valve pushes it in again for recycling, preventing hydrogen waste and making the concentration of the exhaust gas meet the standard value and discharging it directly into the atmosphere.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the conventional technology described above, gas-liquid separation is first performed using a gas-water separator, and then hydrogen is separated using a hydrogen membrane separator. Because the gas introduced into the hydrogen membrane separator by the gas-liquid separator contains many miscellaneous gases, the separation efficiency of the hydrogen membrane separator decreases, and a pressure accumulation step must be performed in combination with detection by a pressure sensor, making the process complex.

[0006] Therefore, the inventors believed that the above-mentioned shortcomings could be improved, and after diligent research, arrived at the present invention, which effectively improves the above-mentioned problems through a rational design.

[0007] This invention has been made in view of the above-mentioned conventional problems. To solve the above problems, the main objective of this invention is to provide a fuel cell system that improves the utilization rate of mixed fuel. [Means for solving the problem]

[0008] To solve the above problems, the fuel cell system of the present invention employs the following means. A fuel cell system according to one aspect of the present invention comprises a fuel cell, a selective separator, and a water trap. The fuel cell has an anode input terminal, a cathode input terminal, an anode output terminal, and a cathode output terminal. The selective separator has a supply terminal connected to the anode output terminal, a hydrogen discharge terminal, and a residual air discharge terminal. , selection Selective membrane technology Separation Ta Yes, there is a water trap connected to the hydrogen pump, which is connected to the hydrogen discharge terminal and the anode input terminal, a purge valve, which is connected to the residual air discharge terminal, and the cathode output terminal. A mixed fuel is supplied via the anode input terminal, and air is supplied via the cathode input terminal. The mixed fuel contains hydrogen and a diluent, and the hydrogen concentration of the mixed fuel is in the range of 2 vol% to 99 vol%. The fuel cell reacts a fuel mixture with air, then supplies the anode gas containing excess hydrogen and diluent from the anode output terminal to a selective separator, and supplies the cathode gas containing excess air from the cathode output terminal to a water trap. After supplying the anode gas to the selective separator, a pressure difference is generated by a hydrogen pump to push the hydrogen from the anode gas back to the anode input terminal via the hydrogen pump from the hydrogen discharge terminal, while the excess anode gas is supplied to the water trap via the residual air discharge terminal and purge valve. When cathode gas and excess anode gas are supplied to the water trap, exhaust gas and water are generated.

[0009] In a preferred example of the present invention, the system further comprises a flow controller, a control unit, and a hydrogen analyzer, wherein the flow controller is connected to an anode input terminal, the hydrogen analyzer is connected to a hydrogen discharge terminal, and the control unit is connected to a fuel cell, a hydrogen pump, the flow controller, and the hydrogen analyzer. The mixed fuel is supplied to the anode input terminal by the flow controller, the control unit obtains the hydrogen supply concentration from the flow controller, the battery stack voltage from the fuel cell, and the hydrogen recovery concentration or recovery flow rate from the hydrogen analyzer. The control unit compares the battery stack voltage with a predetermined voltage range, and if the battery stack voltage is not within the predetermined voltage range, the control unit controls the hydrogen pump to modify the magnitude of the pressure difference based on the supply concentration, battery stack voltage, and recovery concentration or recovery flow rate.

[0010] In a preferred example of the present invention, a mixer is further connected to the anode input terminal, and hydrogen and a diluent are supplied to the mixer, respectively, and then mixed by the mixer as a mixed fuel.

[0011] In a preferred example of the present invention, an auxiliary selective separator is further provided, which has an auxiliary supply terminal connected to a hydrogen pump, and hydrogen of the anode gas and the mixed fuel are supplied to the anode input terminal by the auxiliary selective separator, and the auxiliary selective separator has an auxiliary hydrogen discharge terminal connected to the anode input terminal and an auxiliary residual air discharge terminal connected to the supply terminal.

[0012] In a preferred example of the present invention, the fuel cell is further electrically connected to an electronic load or grid tie device, and after the fuel cell has reacted, electrical energy is transmitted to the electronic load or grid tie device.

[0013] In a preferred example of the present invention, the fuel cell has adjacent anode and cathode plates, the anode plate includes an anode channel, and the cathode plate includes a cathode channel. The anode input terminal and anode output terminal are connected to both ends of the anode channel, and the cathode input terminal and cathode output terminal are connected to both ends of the cathode channel. The length of the anode channel along the anode channel from the anode input terminal to the anode output terminal is different from the length of the cathode channel along the cathode channel from the cathode input terminal to the cathode output terminal.

[0014] In a preferred example of the present invention, the hydrogen concentration in the exhaust gas is less than 4 vol%.

[0015] In a preferred example of the present invention, the fuel cell is one of a proton exchange membrane fuel cell (PEM), an ion exchange membrane fuel cell, and a solid oxide fuel cell.

[0016] In a preferred example of the present invention, the diluent is an inert gas.

[0017] (Effects of the invention) Thus, the present invention provides the following effects. 1. The anode gas is first supplied to the water trap by the purge valve after hydrogen is separated by the selective separator. The hydrogen separation efficiency is increased, and the hydrogen concentration in the exhaust gas can be effectively reduced to less than 4 vol%. 2. Use a selective separator and generate a pressure difference by a hydrogen pump. The pressure accumulation step is not required, and hydrogen can be returned to the anode input terminal without requiring separate energy, further effectively improving the fuel utilization rate of the entire system in a situation where a fuel shortage effect exists. 3. Combine a control unit to perform feedback control to further reduce the hydrogen concentration in the exhaust gas and achieve the target amount of hydrogen consumption. 4. Adopt a mixed fuel in which hydrogen is combined with a diluent to save the usage cost of pure hydrogen. 5. Combine an auxiliary selective separator to reduce the burden on the selective separator and at the same time further enhance the hydrogen separation effect.

[0018] Other features of the present invention will be clarified by the descriptions in this specification and the accompanying drawings.

Brief Description of the Drawings

[0019] [Figure 1] It is a block diagram showing a fuel cell system according to the first embodiment of the present invention. [Figure 2] It is a schematic plan view showing an anode plate according to the first embodiment of the present invention. [Figure 3] It is a schematic plan view showing a cathode plate according to the first embodiment of the present invention. [Figure 4] It is a block diagram showing a fuel cell system according to the second embodiment of the present invention. [Figure 5] It is a relational diagram showing the voltage, hydrogen concentration, and time of a 3 vol% mixed fuel according to the first embodiment of the present invention. [Figure 6] It is a relational diagram showing the voltage, hydrogen concentration, and time of a 40 vol% mixed fuel according to the first embodiment of the present invention. [Figure 7]This is a diagram showing the relationship between voltage, hydrogen concentration, and time for a 50 vol% mixed fuel according to the first embodiment of the present invention. [Figure 8] This is a diagram showing the relationship between voltage, hydrogen concentration, and time for a 99 vol% mixed fuel according to the first embodiment of the present invention. [Modes for carrying out the invention]

[0020] Embodiments of the present invention will be described in detail below. However, the present invention is not limited thereto, and various modifications are possible within the scope described. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of the present invention.

[0021] First, an example of a specific embodiment of a fuel cell system that can improve the utilization rate of a mixed fuel according to the first embodiment of the present invention will be described with reference to Figures 1 to 3.

[0022] (First embodiment) The fuel cell system according to the present invention, which can improve the utilization rate of the mixed fuel, mainly comprises the following components. The configuration of each component will be described below.

[0023] First, the fuel cell 1 has an anode input terminal 11, a cathode input terminal 12, an anode output terminal 13, and a cathode output terminal 14. The fuel cell 1 is one of a proton exchange membrane fuel cell (PEMFC), an ion exchange membrane fuel cell (AEMFC), and a solid oxide fuel cell (SOFC), and in actual implementation, a battery stack may be made up of multiple fuel cells 1.

[0024] More specifically, the fuel cell 1 comprises an adjacent anode plate 15 and a cathode plate 16, the anode plate 15 having an anode flow path 151 and the cathode plate 16 having a cathode flow path 161. The anode input terminal 11 and anode output terminal 13 are connected to both ends of the anode flow path 151, and the cathode input terminal 12 and cathode output terminal 14 are connected to both ends of the cathode flow path 161.

[0025] The length of the anode channel 151 from the anode input terminal 11 to the anode output terminal 13 is different from the length of the cathode channel 161 from the cathode input terminal 12 to the cathode output terminal 14.

[0026] The selective separator 2 has a supply terminal 21 connected to the anode output terminal 13, a hydrogen discharge terminal 22, and a residual air discharge terminal 23.

[0027] The selective separator 2 is one of the following: a pressure-assisted adsorption (PSA) separator, a selective chemical oxidation (PROX) separator, a selective membrane separator, a metal hydride separator, and a cryogenic distillation separator. In this embodiment, the selective membrane separator is selected.

[0028] Hydrogen pump 3 is connected to hydrogen discharge terminal 22 and anode input terminal 11.

[0029] The purge valve 4 is connected to the residual air discharge terminal 23.

[0030] Water trap 5 is connected to cathode output terminal 14.

[0031] The flow controller 6 is connected to the anode input terminal 11.

[0032] The control unit 7 receives signals from the fuel cell 1, hydrogen pump 3, flow controller 6, and hydrogen analyzer 8.

[0033] The hydrogen analyzer 8 is connected to the hydrogen discharge terminal 22.

[0034] When using a fuel cell system that can improve the utilization rate of the mixed fuel, the flow controller 6 first supplies the mixed fuel A to the anode input terminal 11 and air B to the cathode input terminal 12.

[0035] In actual implementation, a mixer (not shown) connected to the anode input terminal 11 may be provided, and hydrogen and diluent are supplied to the mixer by the flow controller 6, and then mixed by the mixer as mixed fuel A, thereby saving on the cost of using pure hydrogen.

[0036] In this embodiment, the hydrogen supply concentration of mixed fuel A is in the range of 2 vol% to 99 vol%, and an inert gas such as nitrogen may be selected as a diluent. Furthermore, the percentages of various concentrations in this invention refer to volume percentage concentrations.

[0037] Inside the fuel cell 1, an anode plate 15 and a cathode plate 16 are arranged. According to Graham's Law, the square root of the gas molecular weight is inversely proportional to the molecular velocity. Therefore, the mixed fuel A first separates the hydrogen, which has a lower molecular weight, and then preferentially reacts the hydrogen with air B.

[0038] Fuel cell 1 reacts the mixed fuel A and air B, then supplies the anode gas containing excess hydrogen and diluent from the anode output terminal 13 to the selective separator 2, and supplies the cathode gas containing excess air B from the cathode output terminal 14 to the water trap 5.

[0039] After supplying the anode gas to the selective separator 2, a pressure difference is generated by the hydrogen pump 3 to push the hydrogen from the anode gas back to the anode input terminal 11 via the hydrogen pump 3 from the hydrogen discharge terminal 22. This eliminates the need to perform a pressure accumulation step and requires no additional energy, and it can also more effectively increase the overall fuel utilization rate of the system in situations where a fuel depletion effect exists. Excess anode gas is supplied to the water trap 5 from the residual air discharge terminal 23 via the purge valve 4.

[0040] In this case, the control unit 7 obtains the hydrogen supply concentration from the flow controller 6, the battery stack voltage from the fuel cell 1, and, based on the type of hydrogen analyzer 8, obtains the hydrogen recovery concentration or recovery flow rate from the hydrogen analyzer 8.

[0041] The control unit 7 compares the battery stack voltage with a predetermined voltage range. If the battery stack voltage is not within the predetermined voltage range, the control unit 7 controls the hydrogen pump 3 to modify the magnitude of the pressure difference based on the supply concentration, battery stack voltage, and recovery concentration or recovery flow rate. If the battery stack voltage is within the predetermined voltage range, there is no need to modify the magnitude of the pressure difference.

[0042] The cathode gas and excess anode gas are supplied to the water trap 5, where they are finally separated to produce exhaust gas C and water D, and the hydrogen concentration of exhaust gas C becomes less than 4 vol%, i.e., less than 40,000 ppm. The water trap 5 discharges the water after condensing the water vapor into water D.

[0043] In actual implementation, the fuel cell 1 may have an electronic load (not shown) or a grid tie device (not shown) electrically connected to it, and after the fuel cell 1 reacts, the generated electrical energy is transmitted to the electronic load or grid tie device and then used.

[0044] The anode gas is first separated for hydrogen by a selective separator 2, and then supplied to a water trap 5 by a purge valve 4, thereby increasing hydrogen separation efficiency and efficiently reducing the hydrogen concentration in exhaust gas C to less than 4 vol%.

[0045] By combining it with control unit 7 and performing feedback control, the hydrogen concentration in exhaust gas C is further reduced, achieving the target amount of hydrogen consumption.

[0046] (Second example) Figure 4 shows the configuration of a fuel cell system that can improve the utilization rate of mixed fuel according to a second embodiment of the present invention. This embodiment differs from the first embodiment in that an auxiliary selective separator 9 is added, but all the remaining components and their arrangement are the same as in the first embodiment, and the explanation of the similarities is omitted.

[0047] The auxiliary selective separator 9 has an auxiliary supply terminal 91 connected to the hydrogen pump 3, and hydrogen from the anode gas and mixed fuel A are supplied to the anode input terminal 11 by the auxiliary selective separator 9. The auxiliary selective separator 9 further has an auxiliary hydrogen discharge terminal 92 connected to the anode input terminal 11, and an auxiliary residual air discharge terminal 93 connected to the supply terminal 21.

[0048] In the operation, the mixed fuel A is first separated by the auxiliary selective separator 9 to increase the hydrogen concentration supplied to the fuel cell 1. The anode gas after the reaction is separated by the selective separator 2 and then returned to the auxiliary selective separator 9 for a second separation, reducing the load on the selective separator 2 while further enhancing the hydrogen separation effect.

[0049] Gases other than hydrogen discharged from the auxiliary residual air discharge terminal 93 enter the selective separator 2 and are discharged from the residual air discharge terminal 23.

[0050] Refer to Figures 5 to 8, and also refer to Figure 1. The arrangement of the first embodiment will be used to actually test the power generation performance and the effects of different hydrogen supply concentrations on exhaust gas C.

[0051] Figures 5 to 8 show the process of supplying hydrogen to a fuel cell system capable of improving the utilization rate of a 10,000-watt mixed fuel by setting the supply concentration to 3 vol%, 40 vol%, 50 vol%, and 99 vol%, respectively. The hydrogen pump 3 is then operated at maximum power for at least 15 minutes to stabilize the system, after which the battery stack voltage and the hydrogen concentration of exhaust gas C are recorded. The remaining experimental data are shown in Table 1 below.

[0052] [Table 1]

[0053] As can be seen from the data in Table 1 and Figures 5 to 8 above, the fuel cell system according to the present invention, which can improve the utilization rate of the mixed fuel, reliably maintains a good power generation effect under different supply concentration conditions and effectively ensures that the hydrogen concentration of exhaust gas C is less than 4 vol%.

[0054] The above description is for the purpose of explaining the present invention and should not be interpreted as limiting or restricting the scope of the invention described in the claims. Furthermore, it goes without saying that the configuration of each part of the present invention is not limited to the above embodiments and can be modified in various ways within the technical scope described in the claims. [Explanation of symbols]

[0055] 1 fuel cell 11 Anode input terminals 12 Cathode Input Terminals 13 Anode output terminals 14 Cathode output terminals 15 Anode Plates 151 Anode channel 16 Cathode Plates 161 Cathode channel 2 Selectable Separator 21 Supply terminal 22 Hydrogen emission terminals 23 Residual air discharge terminal 3. Hydrogen pump 4. Purge valve 5 Water trap 6. Flow Controller 7 Control Unit 8. Hydrogen analyzer 9. Auxiliary Selective Separator 91 Auxiliary supply terminal 92 Auxiliary hydrogen emission terminal 93 Auxiliary residual air discharge terminal A Mixed fuel B Air C Exhaust gas D water

Claims

1. A fuel cell having an anode input terminal, a cathode input terminal, an anode output terminal, and a cathode output terminal, A selective separator, which is a selective membrane technology separator, has a supply terminal connected to the anode output terminal, a hydrogen discharge terminal, and a residual air discharge terminal. A hydrogen pump connected to the hydrogen discharge terminal and the anode input terminal, A purge valve connected to the residual air discharge terminal, The water trap connected to the cathode output terminal, Equipped with, A mixed fuel is supplied through the anode input terminal, and air is supplied through the cathode input terminal, the mixed fuel contains hydrogen and a diluent, and the hydrogen supply concentration of the mixed fuel is in the range of 2 vol% to 99 vol% by volume. The fuel cell reacts the mixed fuel and the air, then supplies the excess hydrogen and diluent as anode gas from the anode output terminal to the selective separator, and supplies the excess air as cathode gas from the cathode output terminal to the water trap. After supplying the anode gas to the selective separator, the hydrogen pump generates a pressure difference to push the hydrogen from the anode gas back to the anode input terminal via the hydrogen pump from the hydrogen discharge terminal, and the excess anode gas is supplied to the water trap via the purge valve from the residual air discharge terminal. A fuel cell system characterized in that exhaust gas and water are generated when the cathode gas and excess anode gas are supplied to the water trap.

2. It further comprises a flow controller, a control unit, and a hydrogen analyzer. The flow controller is connected to the anode input terminal, The hydrogen analyzer is connected to the hydrogen discharge terminal, The control unit receives signals from the fuel cell, the hydrogen pump, the flow controller, and the hydrogen analyzer, the mixed fuel is supplied to the anode input terminal by the flow controller, the control unit obtains the hydrogen supply concentration from the flow controller, the battery stack voltage from the fuel cell, the hydrogen recovery concentration or recovery flow rate from the hydrogen analyzer, and the control unit compares the battery stack voltage with a predetermined voltage range. The fuel cell system according to claim 1, characterized in that, if the battery stack voltage is not within the range of the predetermined voltage, the control unit controls the hydrogen pump to modify the magnitude of the pressure difference based on the supply concentration, the battery stack voltage, and the recovery concentration or the recovery flow rate.

3. The system further includes a mixer connected to the anode input terminal, The fuel cell system according to claim 1, characterized in that the hydrogen and the diluent are supplied to the mixer, respectively, and then mixed by the mixer as the mixed fuel.

4. The system further comprises an auxiliary selective separator having an auxiliary supply terminal connected to the hydrogen pump, The fuel cell system according to claim 1, wherein the hydrogen of the anode gas and the mixed fuel are supplied to the anode input terminal by the auxiliary selective separator, and the auxiliary selective separator has an auxiliary hydrogen discharge terminal connected to the anode input terminal and an auxiliary residual air discharge terminal connected to the supply terminal.

5. The fuel cell further comprises an electronic load or grid tie device electrically connected to the fuel cell, The fuel cell system according to claim 1, characterized in that electrical energy is transmitted to the electronic load or the grid tie device after the fuel cell has reacted.

6. The fuel cell has adjacent anode and cathode plates, the anode plate includes an anode channel, and the cathode plate includes a cathode channel. The anode input terminal and the anode output terminal are connected to both ends of the anode flow path, and the cathode input terminal and the cathode output terminal are connected to both ends of the cathode flow path. The fuel cell system according to claim 1, characterized in that the length of the anode flow path along the anode flow path from the anode input terminal to the anode output terminal is different from the length of the cathode flow path along the cathode flow path from the cathode input terminal to the cathode output terminal.

7. The fuel cell system according to claim 1, characterized in that the concentration of hydrogen in the exhaust gas is less than 4 vol% by volume.

8. The fuel cell system according to claim 1, characterized in that the fuel cell is one of a proton exchange membrane fuel cell (PEM), an ion exchange membrane fuel cell, and a solid oxide fuel cell.

9. The fuel cell system according to claim 1, characterized in that the diluent is an inert gas.

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