Fuel cell system capable of improving utilization rate of mixed fuel

Abstract

The invention discloses a fuel cell system capable of improving the utilization rate of mixed fuel, and the system comprises a fuel cell which is provided with an anode input end, a cathode input end, an anode output end, and a cathode output end; the selective separator is provided with an input end, a hydrogen output end and a residual gas output end; a hydrogen pump; a purge valve; and a cooling buffer barrel. Therefore, the hydrogen separation efficiency can be improved, and the concentration of hydrogen in the tail gas is effectively reduced to 4% or below.

Description

Technical Field

[0001] The present invention relates to a fuel cell system, and in particular to a fuel cell system capable of improving the utilization rate of mixed fuel. Background Art

[0002] Fuel cells are one of the most widely used energy sources at present, but traditional fuel cells will waste a lot of hydrogen, which reduces the utilization rate of hydrogen. If the tail exhaust hydrogen concentration exceeds the standard, it will not meet the standard for discharge into the atmosphere, which may pose a safety risk.

[0003] Therefore, Chinese patent announcement No. CN218918965U provides a fuel cell system for improving hydrogen utilization. The system is connected to the stack and includes an inlet pipeline and an outlet pipeline. The outlet pipeline is provided with a gas-water separator, an exhaust control valve, a pressure sensor, a hydrogen membrane separator and a reflux control valve. The reflux control valve controls the gas to flow to the inlet pipeline. A controllable bypass pipeline is also provided between the gas-water separator and the inlet pipeline. The hydrogen discharged during the nitrogen discharge process is separated by the hydrogen membrane separator and re-entered into the stack for recycling through the reflux control valve, which not only avoids the waste of hydrogen, but also makes the tail exhaust hydrogen concentration meet the standard and can be directly discharged into the atmosphere.

[0004] However, the above-mentioned prior patent first uses a gas-water separator to separate gas and liquid, and then uses a hydrogen membrane separator to separate hydrogen. Since there are more impurities in the gas entering the hydrogen membrane separator through the gas-water separator, the separation efficiency of the hydrogen membrane separator will be poor, and it must be combined with a pressure sensor to detect and perform a pressure accumulation step, and the procedure is more complicated. Summary of the invention

[0005] Therefore, an object of the present invention is to provide a fuel cell system that can improve the utilization rate of mixed fuel.

[0006] The present invention provides a fuel cell system capable of improving the utilization rate of mixed fuel, comprising: 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 an input terminal connected to the anode output terminal, a hydrogen output terminal and a residual gas output terminal, and the selective separator is one of a pressure swing adsorption separator, a selective chemical oxidation separator, a selective membrane technology separator, a metal hydride hydrogen storage separator and a frozen distillation separator; a hydrogen pump connected to the hydrogen output terminal and the anode input terminal; a cleaning valve connected to the residual gas output terminal; and a dewatering buffer tank connected to the cathode output terminal; a mixed fuel is input through the anode input terminal, and air is input through the cathode input terminal, and the mixed fuel comprises a Hydrogen and a diluent, and an input concentration of the hydrogen in the mixed fuel is between 2% and 99%; after the fuel cell reacts with the mixed fuel and the air, an anode gas containing the remaining hydrogen and the diluent is output from the anode output end to the selective separator, and a cathode gas containing the remaining air is output from the cathode output end to the dewatering buffer tank; after the anode gas is input into the selective separator, a pressure difference is generated by the hydrogen pump to push the hydrogen in the anode gas from the hydrogen output end through the hydrogen pump back to the anode input end, and the remaining anode gas is output from the residual gas output end through the cleaning valve to the dewatering buffer tank; after the cathode gas and the remaining anode gas are input into the dewatering buffer tank, an exhaust gas and water are generated.

[0007] Furthermore, there are a flow controller, a control unit and a hydrogen analyzer, the flow controller is connected to the anode input end, the hydrogen analyzer is connected to the hydrogen output end, and the control unit signal is connected to the fuel cell, the hydrogen pump, the flow controller and the hydrogen analyzer; the mixed fuel is input to the anode input end via the flow controller, the control unit obtains the input concentration of the hydrogen through the flow controller, obtains a stack voltage through the fuel cell, and obtains a recovery concentration or a recovery flow of the hydrogen through the hydrogen analyzer; after the control unit compares the stack voltage with a preset voltage range, if the stack voltage does not fall within the preset voltage range, the control unit controls the hydrogen pump to change the size of the pressure difference according to the input concentration, the stack voltage and the recovery concentration or the recovery flow.

[0008] Furthermore, a mixer is connected to the anode input end, and the hydrogen and the diluent are respectively input into the mixer and then mixed into the mixed fuel through the mixer.

[0009] Furthermore, there is an auxiliary selective separator, which has an auxiliary input end connected to the hydrogen pump, and the hydrogen and the mixed fuel in the anode gas are input into the anode input end via the auxiliary selective separator. The auxiliary selective separator also has an auxiliary hydrogen output end connected to the anode input end, and an auxiliary residual gas output end connected to the input end.

[0010] Furthermore, an electronic load or a grid-connected machine is electrically connected to the fuel cell. After the fuel cell reacts, electrical energy is transmitted to the electronic load or the grid-connected machine.

[0011] Furthermore, the fuel cell has an adjacent anode plate and a cathode plate, the anode plate has an anode flow channel, the cathode plate has a cathode flow channel, the anode input terminal and the anode output terminal are connected to the two ends of the anode flow channel, the cathode input terminal and the cathode output terminal are connected to the two ends of the cathode flow channel; the length of an anode flow channel along the anode flow channel from the anode input terminal to the anode output terminal is different from the length of a cathode flow channel along the cathode flow channel from the cathode input terminal to the cathode output terminal.

[0012] Wherein, the concentration of the hydrogen in the tail gas is less than 4%.

[0013] Among them, the fuel cell is one of a proton exchange membrane fuel cell, an anion exchange membrane fuel cell and a solid oxide fuel cell.

[0014] Wherein, the diluent is an inert gas.

[0015] According to the above technical features, the following effects can be preferably achieved:

[0016] 1. The anode gas is first separated into hydrogen by a selective separator and then output to the cooling buffer tank through a cleaning valve, which can improve the hydrogen separation efficiency and effectively reduce the concentration of hydrogen in the tail gas to below 4%.

[0017] 2. Using a selective separator and generating a pressure difference through a hydrogen pump not only eliminates the need for pressure accumulation steps and additional energy, but also effectively improves the overall fuel utilization of the system when there is a fuel starvation effect.

[0018] 3. Use feedback control with the control unit to further ensure that the concentration of hydrogen in the exhaust gas is reduced and the target amount of hydrogen consumption is met.

[0019] 4. Using a mixed fuel of diluent and hydrogen can save the cost of using pure hydrogen.

[0020] 5. Use an auxiliary selective separator to reduce the burden on the selective separator and further improve the separation effect of hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 FIG. 4 is a system block diagram of the first embodiment of the present invention.

[0022] Figure 2 FIG. 1 is a schematic plan view of an anode plate according to a first embodiment of the present invention.

[0023] Figure 3 FIG. 1 is a schematic plan view of a cathode plate according to a first embodiment of the present invention.

[0024] Figure 4 FIG. 4 is a system block diagram of a second embodiment of the present invention.

[0025] Figure 5 FIG. 1 is a graph showing the relationship between voltage, hydrogen concentration and time of a 3% mixed fuel according to the first embodiment of the present invention.

[0026] Figure 6 FIG. 1 is a relationship diagram between voltage, hydrogen concentration and time of a 40% mixed fuel according to the first embodiment of the present invention.

[0027] Figure 7 FIG. 1 is a relationship diagram between voltage, hydrogen concentration and time of a 50% mixed fuel according to the first embodiment of the present invention.

[0028] Figure 8 FIG. 1 is a relationship diagram between voltage, hydrogen concentration and time of the 99% mixed fuel according to the first embodiment of the present invention.

[0029] Explanation of the reference numerals: 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 channel; 16-cathode plate; 161-cathode flow channel; 2-selective separator; 21-input terminal; 22-hydrogen output terminal; 23-residual gas output terminal; 3-hydrogen pump; 4-cleaning valve; 5-cooling buffer tank; 6-flow controller; 7-control unit; 8-hydrogen analyzer; 9-auxiliary selective separator; 91-auxiliary input terminal; 92-auxiliary hydrogen output terminal; 93-auxiliary residual gas output terminal; A-mixed fuel; B-air; C-exhaust gas; D-water. DETAILED DESCRIPTION

[0030] In view of the above technical features, the main effect of the fuel cell system of the present invention in improving the utilization rate of mixed fuel can be clearly presented in the following embodiments.

[0031] See also Figures 1 to 3 , discloses a first embodiment of a fuel cell system capable of improving the utilization rate of mixed fuels of the present invention, which comprises:

[0032] A 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 anion exchange membrane fuel cell (AEMFC) and a solid oxide fuel cell (SOFC). In actual implementation, a plurality of fuel cells 1 can also form a stack.

[0033] In more detail, the fuel cell 1 has an adjacent anode plate 15 and a cathode plate 16, the anode plate 15 has an anode channel 151, the cathode plate 16 has a cathode channel 161, the anode input terminal 11 and the anode output terminal 13 are connected to the two ends of the anode channel 151, and the cathode input terminal 12 and the cathode output terminal 14 are connected to the two ends of the cathode channel 161.

[0034] An anode channel length from the anode input terminal 11 to the anode output terminal 13 along the anode channel 151 is different from a cathode channel length from the cathode input terminal 12 to the cathode output terminal 14 along the cathode channel 161 .

[0035] A selective separator 2 has an input end 21 connected to the anode output end 13 , a hydrogen output end 22 and a residual gas output end 23 .

[0036] The selective separator 2 is one of a pressure swing adsorption (PSA) separator, a selective chemical oxidation (PROX) separator, a selective membrane separator, a metal hydride hydrogen storage (metalhydride) separator and a cryogenic distillation separator. In this embodiment, a selective membrane separator is selected.

[0037] A hydrogen pump 3 is connected to the hydrogen output terminal 22 and the anode input terminal 11 .

[0038] A purge valve 4 is connected to the residual gas output end 23 .

[0039] A cooling water buffer tank 5 is connected to the cathode output terminal 14 .

[0040] A flow controller 6 is connected to the anode input terminal 11 .

[0041] A control unit 7 is signal-connected to the fuel cell 1 , the hydrogen pump 3 , the flow controller 6 and a hydrogen analyzer 8 .

[0042] The hydrogen analyzer 8 is connected to the hydrogen output terminal 22 .

[0043] When the fuel cell system capable of improving the utilization rate of mixed fuel is used, a mixed fuel A is first input into the anode input end 11 through the flow controller 6 , and air B is input into the cathode input end 12 .

[0044] In actual implementation, there may be a mixer (not shown) connected to the anode input terminal 11, and the hydrogen and diluent are respectively input into the mixer through their respective flow controllers 6, and then mixed into the mixed fuel A through the mixer, which can save the cost of using pure hydrogen.

[0045] In this embodiment, an input concentration of hydrogen in the mixed fuel A is between 2% and 99%, and the diluent may be an inert gas such as nitrogen. In addition, the percentages of various concentrations in the present invention refer to volume percentage concentrations.

[0046] Inside the fuel cell 1, since the anode plate 15 and the 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, so the mixed fuel A will initially separate the hydrogen with a smaller molecular weight, and allow the hydrogen to react with the air B first.

[0047] After the fuel cell 1 reacts with the mixed fuel A and the air B, the anode gas containing the remaining hydrogen and the diluent is output from the anode output end 13 to the selective separator 2, and the cathode gas containing the remaining air B is output from the cathode output end 14 to the cooling buffer tank 5.

[0048] After the anode gas is input into the selective separator 2, a pressure difference is generated through the hydrogen pump 3, pushing the hydrogen in the anode gas from the hydrogen output end 22 back to the anode input end 11 through the hydrogen pump 3, not only eliminating the need for pressure accumulation steps and additional energy, but also effectively improving the overall fuel utilization of the system when the fuel starvation effect exists. The remaining anode gas is output from the residual gas output end 23 to the dewatering buffer tank 5 through the cleaning valve 4.

[0049] At this time, the control unit 7 obtains the input concentration of hydrogen through the flow controller 6, obtains a stack voltage through the fuel cell 1, and obtains a recovery concentration or a recovery flow rate of hydrogen through the hydrogen analyzer 8 according to the type of the hydrogen analyzer 8.

[0050] After the control unit 7 compares the stack voltage with a preset voltage range, if the stack voltage does not fall within the preset voltage range, the control unit 7 controls the hydrogen pump 3 to change the magnitude of the pressure difference according to the input concentration, the stack voltage, and the recovery concentration or the recovery flow rate. If the stack voltage falls within the preset voltage range, there is no need to change the magnitude of the pressure difference.

[0051] After the cathode gas and the remaining anode gas are input into the dewatering buffer tank 5, they are finally separated to produce a tail gas C and water D, and the concentration of hydrogen in the tail gas C is less than 4%, that is, less than 40000 ppm.

[0052] In actual implementation, there may also be an electronic load or a grid-connected machine (not shown) electrically connected to the fuel cell 1. After the fuel cell 1 reacts, the electrical energy generated can be transmitted to the electronic load or the grid-connected machine for subsequent use.

[0053] Since the anode gas is first separated into hydrogen by the selective separator 2 and then output to the cooling buffer tank 5 through the cleaning valve 4, the hydrogen separation efficiency can be improved and the concentration of hydrogen in the tail gas C can be effectively reduced to below 4%.

[0054] The feedback control performed by the control unit 7 can further ensure that the concentration of hydrogen in the exhaust gas C is reduced and the target amount of hydrogen consumption is met.

[0055] See also Figure 4 , revealing the second embodiment of the fuel cell system of the present invention which can improve the utilization rate of mixed fuel. The difference between this embodiment and the first embodiment is that: this embodiment adds an auxiliary selective separator 9, and the remaining components and configurations are the same as the first embodiment, and this embodiment will not be introduced one by one.

[0056] The auxiliary selective separator 9 has an auxiliary input terminal 91 connected to the hydrogen pump 3. The hydrogen in the anode gas and the mixed fuel A are input into the anode input terminal 11 via the auxiliary selective separator 9. The auxiliary selective separator 9 also has an auxiliary hydrogen output terminal 92 connected to the anode input terminal 11, and an auxiliary residual gas output terminal 93 connected to the input terminal 21.

[0057] In operation, the mixed fuel A is first separated by the auxiliary selective separator 9 to increase the concentration of the hydrogen input to the fuel cell 1. The anode gas after the reaction is first separated by the selective separator 2 and then returns to the auxiliary selective separator 9 for a second separation, thereby reducing the burden on the selective separator 2 and further improving the separation effect of hydrogen.

[0058] The non-hydrogen gas output from the auxiliary residual gas output end 93 enters the selective separator 2 so as to be discharged from the residual gas output end 23 .

[0059] See also Figures 5 to 8 , and please match Figure 1 The configuration of the first embodiment is used to test the influence of different input concentrations of hydrogen on the power generation performance and the exhaust gas C.

[0060] Figures 5 to 8The input concentration was configured to be 3%, 40%, 50% and 99% respectively, and hydrogen was input into the fuel cell system with a power generation capacity of 10 kilowatts that can improve the utilization rate of the mixed fuel. The hydrogen pump 3 was operated at the highest power for at least 15 minutes. After the system was stable, the stack voltage and the concentration of hydrogen in the exhaust gas C were recorded respectively. The rest of the experimental data are shown in Table 1 below.

[0061] Table 1. Experimental data

[0062]

[0063] From the above table 1 and Figures 5 to 8 It can be seen from the data that the fuel cell system of the present invention that can improve the utilization rate of the mixed fuel can indeed maintain a good power generation effect under conditions of different input concentrations and effectively ensure that the concentration of hydrogen in the exhaust gas C is below 4%.

[0064] Based on the description of the above embodiments, the operation, use and effects of the present invention can be fully understood. However, the above embodiments are only preferred embodiments of the present invention and should not be used to limit the scope of the present invention. That is, simple equivalent changes and modifications made according to the claims and the description of the present invention are all within the scope of the present invention.

Claims

1. A fuel cell system capable of improving the utilization rate of mixed fuel, characterized in that: Include: 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 an input end connected to the anode output end, a hydrogen output end and a residual gas output end, and the selective separator is one of a pressure swing adsorption separator, a selective chemical oxidation separator, a selective membrane technology separator, a metal hydride hydrogen storage separator and a cryodistillation separator; a hydrogen pump connected to the hydrogen output end and the anode input end; a purge valve connected to the residual gas output end; and A cooling water buffer tank connected to the cathode output terminal; A mixed fuel is input through the anode input end, and air is input through the cathode input end, wherein the mixed fuel includes hydrogen and a diluent, and an input concentration of the hydrogen in the mixed fuel is between 2% and 99% by volume; After the fuel cell reacts with the mixed fuel and the air, an anode gas containing the remaining hydrogen and the diluent is output from the anode output end to the selective separator, and a cathode gas containing the remaining air is output from the cathode output end to the cooling buffer tank; After the anode gas is input into the selective separator, a pressure difference is generated by the hydrogen pump, pushing the hydrogen in the anode gas from the hydrogen output end back to the anode input end through the hydrogen pump, and the remaining anode gas is output from the residual gas output end through the cleaning valve to the dewatering buffer tank; After the cathode gas and the remaining anode gas are input into the cooling buffer tank, tail gas and water are generated.

2. The fuel cell system capable of improving the utilization rate of mixed fuel as claimed in claim 1, characterized in that: It also includes a flow controller, a control unit and a hydrogen analyzer, the flow controller is connected to the anode input end, the hydrogen analyzer is connected to the hydrogen output end, and the control unit signal is connected to the fuel cell, the hydrogen pump, the flow controller and the hydrogen analyzer; the mixed fuel is input to the anode input end via the flow controller, the control unit obtains the input concentration of the hydrogen through the flow controller, obtains a stack voltage through the fuel cell, and obtains a recovery concentration or a recovery flow of the hydrogen through the hydrogen analyzer; after the control unit compares the stack voltage with a preset voltage range, if the stack voltage does not fall within the preset voltage range, the control unit controls the hydrogen pump to change the size of the pressure difference according to the input concentration, the stack voltage and the recovery concentration or the recovery flow.

3. The fuel cell system capable of improving the utilization rate of mixed fuel as claimed in claim 1, characterized in that: The invention also comprises a mixer connected to the anode input end. The hydrogen and the diluent are respectively input into the mixer and then mixed into the mixed fuel through the mixer.

4. The fuel cell system capable of improving the utilization rate of mixed fuel as claimed in claim 1, characterized in that: It also includes an auxiliary selective separator, which has an auxiliary input end connected to the hydrogen pump. The hydrogen and the mixed fuel in the anode gas are input into the anode input end via the auxiliary selective separator. The auxiliary selective separator also has an auxiliary hydrogen output end connected to the anode input end, and an auxiliary residual gas output end connected to the input end.

5. The fuel cell system capable of improving the utilization rate of mixed fuel as claimed in claim 1, characterized in that: It also includes an electronic load or a grid-connected machine electrically connected to the fuel cell. After the fuel cell reacts, the electric energy is transmitted to the electronic load or the grid-connected machine.

6. The fuel cell system capable of improving the utilization rate of mixed fuel as claimed in claim 1, characterized in that: The fuel cell has an adjacent anode plate and a cathode plate, the anode plate has an anode flow channel, the cathode plate has a cathode flow channel, the anode input end and the anode output end are connected to the two ends of the anode flow channel, the cathode input end and the cathode output end are connected to the two ends of the cathode flow channel; the length of an anode flow channel along the anode flow channel from the anode input end to the anode output end is different from the length of a cathode flow channel along the cathode flow channel from the cathode input end to the cathode output end.

7. The fuel cell system capable of improving the utilization rate of mixed fuel as claimed in claim 1, characterized in that: The concentration of the hydrogen in the tail gas is less than 4% by volume.

8. The fuel cell system capable of improving the utilization rate of mixed fuel as claimed in claim 1, characterized in that: The fuel cell is one of a proton exchange membrane fuel cell, an anion exchange membrane fuel cell and a solid oxide fuel cell.

9. The fuel cell system capable of improving the utilization rate of mixed fuel as claimed in claim 1, characterized in that: The diluent is an inert gas.

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