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 a mixed fuel. [Background technology]

[0002] Fuel cells are one of the most widely used energy sources today, but conventional fuel cells waste a lot of hydrogen and have a low hydrogen utilization rate. In addition, there is a risk of danger if the exhaust gas concentration exceeds the standard value and does not meet the standard for atmospheric emission.

[0003] Prior patent documents, such as Patent Document 1, disclose a "fuel cell system for improving hydrogen utilization rate." The fuel cell system is connected to an electrode pile and includes a push-in pipeline and an extrusion pipeline. An air-water separator, an exhaust control valve, a pressure sensor, a hydrogen membrane separator, and a recirculation control valve are installed in the extrusion pipeline, and the recirculation control valve controls the gas to flow into the push-in pipeline. A controllable bypass pipeline is further installed between the air-water separator and the push-in pipeline. The hydrogen membrane separator separates hydrogen discharged during the nitrogen discharge process, and the hydrogen is re-pushed in by the recirculation control valve for recycling, preventing hydrogen waste while ensuring that the exhaust gas concentration meets the standard value, and is directly discharged into the atmosphere. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] China Registered Utility Model No. 218918965U Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned conventional technology, gas-liquid separation is first performed by the water-air separator, and then hydrogen is separated by the hydrogen membrane separator. Since the gas that the water-air separator causes to enter the hydrogen membrane separator contains many miscellaneous gases, the separation efficiency of the hydrogen membrane separator is reduced, and a pressure accumulation step must be performed in combination with detection by a pressure sensor, making the process complicated.

[0006] Therefore, the present inventors believed that the above-mentioned drawbacks could be improved, and as a result of extensive research, they came to propose the present invention, which effectively improves the above-mentioned problems through rational design.

[0007] The present invention has been made in view of the above-mentioned problems in the conventional technology, and has as its main object to provide a fuel cell system that improves the utilization rate of the mixed fuel. [Means for solving the problem]

[0008] In order to solve the above problems, the fuel cell system of the present invention employs the following measures. A fuel cell system according to an embodiment of the present invention includes 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, and is one of a pressure shift adsorption separator, a selective chemical oxidation separator, a selective membrane technology separator, a metal hydride hydrogen storage separator, and a freeze distillation separator. The water trap is connected to a hydrogen pump connected to the hydrogen discharge terminal and the anode input terminal, a purge valve connected to the residual air discharge terminal, and to the cathode output terminal. The anode input terminal supplies a fuel mixture, and the cathode input terminal supplies air, the fuel mixture includes hydrogen and a diluent, and the hydrogen supply concentration of the fuel mixture ranges between 2 vol% and 99 vol%. The fuel cell reacts the mixed fuel and air, then supplies an anode gas containing excess hydrogen and diluent from the anode output terminal to a selective separator, and supplies a cathode gas containing excess air from the cathode output terminal to a water trap. After the anode gas is supplied to the selective separator, a pressure difference is generated by a hydrogen pump to push the hydrogen in the anode gas from the hydrogen discharge terminal back to the anode input terminal via the hydrogen pump, and the excess anode gas is supplied from the residual air discharge terminal to the water trap via a purge valve. When the cathode gas and excess anode gas are fed into the water trap, exhaust gas and water are produced.

[0009] In a preferred embodiment of the present invention, the system further comprises a flow controller, a control unit, and a hydrogen analyzer, the flow controller being connected to the anode input terminal, the hydrogen analyzer being connected to the hydrogen discharge terminal, and the control unit being connected to signals of 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, and the control unit obtains the supply concentration of hydrogen by the flow controller, the cell stack voltage by the fuel cell, and the recovery concentration or recovery flow rate of hydrogen by the hydrogen analyzer. The control unit compares the cell stack voltage with a predetermined voltage range, and if the cell 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, the cell stack voltage, and the recovery concentration or recovery flow rate.

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

[0011] In a preferred embodiment of the present invention, the system further comprises an auxiliary selective separator having 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, the auxiliary selective separator having 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 embodiment of the present invention, the fuel cell further comprises an electronic load or grid tie device electrically connected to the fuel cell, and after the fuel cell reacts, electrical energy is transferred to the electronic load or grid tie device.

[0013] In a preferred embodiment of the invention, the fuel cell has adjacent anode and cathode plates, the anode plate including an anode flow path and the cathode plate including a cathode flow path. An anode input terminal and an anode output terminal are connected to opposite ends of the anode flow path, and a cathode input terminal and a cathode output terminal are connected to opposite ends of the cathode flow path. 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.

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

[0015] In a preferred embodiment of the 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 embodiment of the present invention, the diluent is an inert gas.

[0017] (Effects of the Invention) Thus, according to the present invention, the following effects are achieved. 1. Hydrogen is first separated from the anode gas by a selective separator, and then the gas is supplied to the water trap by the purge valve. This increases the efficiency of hydrogen separation, effectively reducing the hydrogen concentration in the exhaust gas to less than 4 vol%. 2. Using a selective separator, a pressure difference is generated by a hydrogen pump, which does not require a pressure accumulation step and does not require additional energy to return hydrogen to the anode input terminal, which further effectively improves the fuel utilization rate of the entire system in the presence of fuel starvation effect. 3. Combine the 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. The use of mixed fuel that combines hydrogen as a diluent reduces the cost of using pure hydrogen. 5. By combining an auxiliary selective separator, the burden on the selective separator can be reduced while at the same time further enhancing the hydrogen separation effect.

[0018] Other features of the present invention will become apparent from the following detailed description of the present invention and the accompanying drawings. [Brief description of the drawings]

[0019] [Figure 1] 1 is a block diagram showing a fuel cell system according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic plan view showing an anode plate according to the first embodiment of the present invention. [Diagram 3] FIG. 2 is a schematic plan view showing a cathode plate according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a block diagram showing a fuel cell system according to a second embodiment of the present invention. [Diagram 5] FIG. 4 is a relationship diagram showing voltage, hydrogen concentration, and time for a 3 vol % mixed fuel according to the first embodiment of the present invention. [Figure 6] FIG. 4 is a relationship diagram showing voltage, hydrogen concentration, and time for a 40 vol % mixed fuel according to the first embodiment of the present invention. [Figure 7]FIG. 4 is a relationship diagram showing voltage, hydrogen concentration, and time for a 50 vol % mixed fuel according to the first embodiment of the present invention. [Figure 8] FIG. 4 is a relationship diagram showing voltage, hydrogen concentration, and time for 99 vol % mixed fuel according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, the embodiments of the present invention will be described in detail. However, the present invention is not limited to these, and various modifications are possible within the scope of the description. The technical scope of the present invention also includes embodiments obtained by appropriately combining the technical means disclosed in the different embodiments.

[0021] First, an example of a specific embodiment of a fuel cell system capable of improving the utilization rate of a mixed fuel according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG.

[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 cell stack may be formed by a plurality of fuel cells 1.

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

[0025] The length of the anode flow channel along the anode flow channel 151 from the anode input terminal 11 to the anode output terminal 13 is different from the length of the cathode flow channel along the cathode flow 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 a pressure-shifting adsorption (PSA) separator, a selective chemical oxidation (PROX) separator, a selective membrane separator, a metal hydride hydrogen storage separator, and a cryogenic distillation separator, and in this embodiment, a selective membrane separator is selected.

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

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

[0030] The water trap 5 is connected to the cathode output terminal 14 .

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

[0032] The control unit 7 is connected to signals of the fuel cell 1, the hydrogen pump 3, the flow controller 6, and the hydrogen analyzer 8.

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

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

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

[0036] In this embodiment, the hydrogen supply concentration of the 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. Moreover, the percentages of various concentrations in the present invention refer to volume percentage concentrations.

[0037] An anode plate 15 and a cathode plate 16 are arranged inside the fuel cell 1. According to Graham's Law, the square root of the gas molecular weight is inversely proportional to the molecular velocity. Therefore, hydrogen with a small molecular weight is first separated from the mixed fuel A, and the hydrogen is reacted preferentially with air B.

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

[0039] After the anode gas is supplied to the selective separator 2, a pressure difference is generated by the hydrogen pump 3 to push the hydrogen in the anode gas from the hydrogen discharge terminal 22 back to the anode input terminal 11 via the hydrogen pump 3. Not only is there no need to perform a pressure accumulation step and no additional energy required, but the fuel utilization rate of the entire system can be more effectively improved in a situation where the fuel starvation effect exists. The surplus anode gas is supplied from the residual air discharge terminal 23 to the water trap 5 via the purge valve 4.

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

[0041] The control unit 7 compares the cell stack voltage with a predetermined voltage range, and if the cell 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, the cell stack voltage, and the recovery concentration or recovery flow rate. If the cell 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, and then finally separated to generate exhaust gas C and water D, and the hydrogen concentration of the exhaust gas C is less than 4 vol%, i.e., less than 40,000 ppm. The water trap 5 condenses the water vapor into water D and then discharges it.

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

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

[0045] By combining with the control unit 7 to perform feedback control, the hydrogen concentration in the exhaust gas C is further reduced to achieve the target amount of hydrogen consumption.

[0046] (Second Example) The configuration of a fuel cell system capable of improving the utilization rate of mixed fuel according to a second embodiment of the present invention is shown in Fig. 4. This embodiment differs from the first embodiment in that an auxiliary selective separator 9 is added, but the remaining members and arrangement are all the same as in the first embodiment, and a description of the similarities will be omitted.

[0047] The auxiliary selective separator 9 has an auxiliary supply terminal 91 connected to the hydrogen pump 3, and hydrogen of 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 operation, mixed fuel A is first separated by auxiliary selective separator 9 to increase the hydrogen concentration supplied to fuel cell 1. The anode gas after reaction is separated by selective separator 2 and then returned to auxiliary selective separator 9 for a second separation, reducing the burden on selective separator 2 while further improving 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] Please refer to Figures 5 to 8, and also to Figure 1. By using the arrangement of the first embodiment, the effects of different supply concentrations of hydrogen on the power generation performance and the exhaust gas C are actually tested.

[0051] 5 to 8, the supply concentration was set to 3 vol%, 40 vol%, 50 vol%, and 99 vol%, respectively, hydrogen was supplied to a fuel cell system capable of improving the utilization rate of the mixed fuel with a generating power of 10,000 watts, the hydrogen pump 3 was operated to its maximum power, and the system was allowed to stabilize for at least 15 minutes, after which the cell stack voltage and the hydrogen concentration of the exhaust gas C were recorded. The remaining experimental data are shown in Table 1 below.

[0052] [Table 1]

[0053] As can be seen from Table 1 above and the data in Figures 5 to 8, the fuel cell system capable of improving the utilization rate of the mixed fuel of the present invention reliably maintains good power generation efficiency 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 the invention described in the claims or restricting the scope of the invention. Furthermore, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications are possible within the technical scope described in the claims. [Explanation of symbols]

[0055] 1 fuel cell 11 Anode input terminal 12 Cathode input terminal 13 Anode output terminal 14 Cathode output terminal 15 Anode plate 151 Anode flow path 16 Cathode plate 161 Cathode flow path 2 Selective separator 21 Supply terminal 22 Hydrogen discharge terminal 23 Residual air exhaust terminal 3 Hydrogen pump 4 Purge Valve 5. Water Trap 6 Flow Controller 7. Control Unit 8 Hydrogen Analyzer 9. Auxiliary Selection Separator 91 Auxiliary supply terminal 92 Auxiliary hydrogen discharge terminal 93 Auxiliary residual air exhaust 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 having a supply terminal connected to the anode output terminal, a hydrogen discharge terminal, and a residual air discharge terminal, the selective separator being one of a pressure shift adsorption separator, a selective chemical oxidation separator, a selective membrane technology separator, a metal hydride hydrogen storage separator, and a cryo-distillation separator; a hydrogen pump connected to the hydrogen discharge terminal and the anode input terminal; a purge valve connected to the residual air exhaust terminal; a water trap connected to the cathode output terminal; Equipped with A fuel mixture is supplied through the anode input terminal and air is supplied through the cathode input terminal, the fuel mixture includes hydrogen and a diluent, and the hydrogen supply concentration of the fuel mixture is in a range of 2 vol% to 99 vol% by volume; the fuel cell reacts the mixed fuel and the air, and then supplies an anode gas containing the excess hydrogen and the diluent from the anode output terminal to the selective separator, and supplies a cathode gas containing the excess air from the cathode output terminal to the water trap; the anode gas is supplied to the selective separator, and then a pressure difference is generated by the hydrogen pump to push the hydrogen in the anode gas from the hydrogen discharge terminal back to the anode input terminal via the hydrogen pump, and excess anode gas is supplied from the residual air discharge terminal via the purge valve to the water trap; A fuel cell system, characterized in that, when the cathode gas and excess anode gas are supplied to the water trap, exhaust gas and water are generated.

2. Further comprising 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 is connected to signals of 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 supply concentration of hydrogen by the flow controller, obtains a cell stack voltage by the fuel cell, and obtains a recovered concentration or recovered flow rate of hydrogen by the hydrogen analyzer, and the control unit compares the cell stack voltage with a predetermined voltage range; 2. The fuel cell system according to claim 1, wherein when the cell 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, the cell stack voltage, and the recovery concentration or the recovery flow rate.

3. a mixer connected to the anode input terminal; 2. The fuel cell system according to claim 1, wherein the hydrogen and the diluent are supplied to the mixer, and then mixed by the mixer to form the mixed fuel.

4. a supplementary selective separator having a supplementary supply terminal connected to the hydrogen pump; 2. 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, the auxiliary selective separator having an auxiliary hydrogen discharge terminal connected to the anode input terminal and an auxiliary residual air discharge terminal connected to the supply terminal.

5. an electronic load or grid tie device electrically connected to the fuel cell; 2. The fuel cell system of claim 1, wherein the fuel cell reacts before transmitting electrical energy to the electronic load or the grid tie device.

6. the fuel cell has adjacent anode and cathode plates, the anode plate including an anode flow channel and the cathode plate including a cathode flow 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, 2. The fuel cell system according to claim 1, wherein an anode flow path length along the anode flow path from the anode input terminal to the anode output terminal is different from a cathode flow path length along the cathode flow path from the cathode input terminal to the cathode output terminal.

7. 2. The fuel cell system according to claim 1, wherein the concentration of said hydrogen in said exhaust gas is less than 4 vol% in terms of volume percentage concentration.

8. 10. The fuel cell system of claim 1, wherein 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. 2. The fuel cell system according to claim 1, wherein the diluent is an inert gas.

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