Fuel cell system and power generation method for fuel cell system

Abstract

To provide a fuel cell system having a compact and long-life poisoning substance filter and a power generation method thereof.SOLUTION: A fuel cell system 100 includes a fuel cell stack 11 for generating power by reacting fuel gas with oxygen-containing gas, an exhaust path 13 for discharging exhaust gas generated by power generation of the fuel cell stack 11 to the outside of the system, a generated water passage 14 for collecting generated water W contained in the exhaust gas, a water cooler 23 which is provided in the generated water passage 14 and can cool the generated water W as appropriate, a filter unit 16 which is connected to the generated water passage 14 on the downstream side of the water cooler 23 and uses the generated water W1 to remove water-soluble poisoning substances from the oxygen-containing gas α to flow into the fuel cell stack 11, and a drainage pipe 35 which is connected to the filter unit 16 and used in the filter unit 16 to discharge the generated water W2 containing the water-soluble poisoning substance to the outside of the system.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fuel cell system having a function of purifying reaction air and a power generation method thereof. [Background technology]

[0002] In general, SO, such as hydrogen sulfide and sulfur dioxide, enters the fuel cell system from the atmosphere. X NO molecules and nitrogen dioxide X These water-soluble poisoning molecules (hereinafter collectively referred to as "water-soluble poisoning substances") are so-called poisoning substances that inhibit chemical reactions in fuel cell stacks. Therefore, accumulation of poisoning substances leads to a decrease in gas diffusibility, a decrease in the conductivity of the solid polymer membrane due to impurity cations, or deterioration of output characteristics. Conventionally, therefore, a poisoning substance filter has been installed in the air supply path of the fuel cell stack to remove these impurities and supply clean air to the fuel cell stack. In addition, taking note of the fact that these water-soluble poisoning substances are easily dissolved in water, a poisoning substance filter that is maintained in a wet state may be used as the poisoning substance filter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 2001-185193 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional techniques have been unable to efficiently remove water-soluble poisonous substances that enter the fuel cell system, resulting in problems such as a short life span and large size of the poisonous substance filter. The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a fuel cell system having a compact, long-life poisoning substance filter, and a power generation method thereof. [Means for solving the problem]

[0005] The fuel cell system of this embodiment comprises a fuel cell that generates electricity by reacting a fuel gas with an oxygen-containing gas, an exhaust path that discharges exhaust gas generated by the power generation of the fuel cell outside the system, a produced water passage that recovers produced water contained in the exhaust gas, a water cooler provided in the produced water passage and capable of cooling the produced water as required, a filter section connected to the produced water passage downstream of the water cooler and using the produced water to remove water-soluble poisoning substances from the oxygen-containing gas attempting to flow into the fuel cell, and a drain pipe connected to the filter section and used by the filter section to discharge the produced water containing the water-soluble poisoning substances outside the system.

[0006] In addition, the power generation method of this embodiment includes the steps of reacting a fuel gas with an oxygen-containing gas to generate power, discharging exhaust gas generated by the power generation of the fuel cell outside the system, recovering the produced water contained in the exhaust gas, timely cooling the produced water flowing through the produced water passage, supplying the produced water to a poisoning substance filter connected to the produced water passage downstream of the water cooler to remove water-soluble poisoning substances from the oxygen-containing gas attempting to flow into the fuel cell, and discharging the produced water used in the poisoning substance filter and containing the water-soluble poisoning substances outside the system. Effect of the Invention

[0007] The present invention provides a fuel cell system having a compact, long-life poisoning substance filter and a power generation method thereof. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of a fuel cell system according to a first embodiment. [Diagram 2] 1 is a graph showing the relationship between temperature and the solubility of hydrogen sulfide in water. [Diagram 3] FIG. 2 is a schematic perspective view of a poisoning substance filter according to the first embodiment. [Figure 4] FIG. 11 is a schematic configuration diagram of a fuel cell system according to a second embodiment. [Diagram 5] FIG. 9 is an enlarged schematic cross-sectional view of a humidifying filter according to a second embodiment, cut along the flow direction of reaction air. [Figure 6] 1A to 1C are diagrams showing a model of a cylindrical air flow path used in the examples. [Figure 7] 4 is a contour map showing the analysis results of hydrogen sulfide concentration distribution in the air flow path. [Figure 8] A graph showing the distribution of hydrogen sulfide concentration in a cross section 1 mm from the inlet. [Figure 9] 1 is a graph showing the results of an analysis of the poisoning substance filter depth and hydrogen sulfide permeability by changing the flow path radius R of the air flow path. [Figure 10] 1 is a graph showing the depth of the poisoning substance filter when the hydrogen sulfide transmittance is 5%. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0010] (First embodiment) FIG. 1 is a schematic diagram of a fuel cell system 100 according to a first embodiment. The fuel cell system 100 mainly comprises a fuel cell stack 11 to which a plurality of flow paths (12-14) are directly or indirectly connected, and peripheral devices (16-23, 25, 26) are provided on the flow paths (12-14). The fuel cell stack 11 is, for example, a solid polymer fuel cell, and generates electricity by reacting a fuel gas such as hydrogen with an oxygen-containing gas, typically air in the atmosphere.

[0011] Below, an example will be described in which atmospheric air (hereinafter referred to as "reactant air") α is supplied as the oxygen-containing gas, and hydrogen is supplied as the fuel gas. Also, an example will be described in which the fuel cell stack 11 is a solid polymer fuel cell. In this example, hydrogen is decomposed into hydrogen ions and electrons at the fuel electrode of the fuel cell stack 11. The hydrogen ions move to the air electrode through the solid polymer membrane, and the electrons flow into the air electrode through an external circuit, where they react with oxygen in the air supplied to the air electrode to produce water.

[0012] To this air electrode, there are connected a supply channel 12 for supplying reactant air α, and a discharge channel 13 for discharging water produced by power generation (produced water) and unreacted air to the outside of the system as exhaust gas. The supply passage 12 is provided with a poisoning substance filter 16, a compressor 17, an air cooler 18, a humidifier 19, and an inlet valve 20 in this order from the upstream side. That is, as viewed from the compressor 17, the poisoning substance filter 16 is provided upstream in the flow direction of the reaction air α, and the air cooler 18, the humidifier 19, and the inlet valve 20 are provided downstream.

[0013] In order to increase the power generation efficiency in the fuel cell stack 11, the compressor 17 compresses the reaction air α in the atmosphere and sends it to the fuel cell stack 11. For this compressor 17, for example, a compressor or a blower is used depending on the required air compression ratio. The air cooler 18 cools the reaction air α whose temperature has been increased by being adiabatically compressed by the compressor 17.

[0014] The humidifier 19 keeps the solid polymer membrane wet by increasing the humidity of the reaction air α flowing into the fuel cell stack 11. In a solid polymer fuel cell, the humidity of the solid polymer membrane affects the conductivity, so this is to prevent a decrease in conductivity. Note that the humidifier 19 is preferably an evaporation type using, for example, a moisture-permeable membrane or a hollow fiber membrane, but the humidification method is not particularly limited. In addition to the evaporation type, a steam supply type, a water spray type, or other appropriate method can be adopted for the humidifier 19.

[0015] In addition, an outlet valve 21 is provided in the exhaust path 13 to adjust the amount of exhaust gas discharged from the fuel cell stack 11 and the pressure of the fuel cell stack 11, and to prevent oxygen from flowing into the fuel cell stack 11 from the outside when the system is stopped. In addition, a produced water passage 14 is connected to the discharge path 13 downstream of the outlet valve 21. Since the pressure on the discharge path 13 side of the fuel cell stack 11 fluctuates, the produced water W whose pressure is constant and which is stable to atmospheric pressure after passing through the outlet valve 21 is utilized.

[0016] The produced water passage 14 is connected to a poisoning substance filter 16 that is installed on the supply passage 12 upstream of the compressor 17. The produced water W that is produced during power generation and contained in the exhaust gas is collected and supplied to the poisoning substance filter 16. The generated water W1 supplied to the poisoning substance filter 16 moistens the poisoning substance filter 16 and removes the above-mentioned hydrogen sulfide, SO 2 , etc. from the reaction air α about to flow into the compressor 17. X Molecules and NO X The poisoning substance filter 16 dissolves and absorbs water-soluble poisoning substances such as toxic molecules. Therefore, the poisoning substance filter 16 prevents water-soluble poisoning substances from the atmosphere from entering the fuel cell stack 11, and reduces factors that inhibit the reaction in the fuel cell system 100.

[0017] Further, a water cooler 23 is provided in the produced water passage 14 to cool the produced water W1 flowing through the produced water passage 14. The water cooler 23 is, for example, a heat exchanger that exchanges heat between the atmosphere and the produced water W1, that is, an air-cooling mechanism such as an intercooler. The water cooler 23 is provided with a bypass pipe 24 that bypasses the water cooler 23, and a bypass valve 25 that is, for example, a three-way solenoid valve. When it is necessary to cool the generated water W1, the bypass side valve of the bypass valve 25 is closed to allow the generated water W1 to flow through the water cooler 23. On the other hand, when the generated water W is at about the temperature of the atmosphere, such as immediately after the start of power generation, heat exchange with the atmosphere is not necessary, so the generated water W1 passes through the bypass pipe 24 and bypasses the water cooler 23. In other words, this structure allows the generated water W1 to be passed through the water cooler 23 to be cooled only when cooling is necessary.

[0018] The water cooler 23 cools the generated water W, which is at about 60 to 90°C when it is discharged to the discharge passage 13, to 40°C or less. Here, Figure 2 is a graph showing the relationship between temperature and the solubility of hydrogen sulfide in water, based on data from the Scientific Chronology.

[0019] As shown in Figure 2, the solubility of hydrogen sulfide in water is expressed by a monotonically decreasing function, where the solubility decreases as the temperature increases. In other words, hydrogen sulfide gas becomes more soluble in water as the temperature decreases. This graph shows that the slope of the graph becomes steeper around 40°C, and the solubility increases significantly below 40°C. In addition, although not shown in the figure, the solubility of SO X Molecules and NO X The molecular system also has a monotonically decreasing function of temperature, with the slope of the graph increasing around 40°C. For example, hydrogen sulfide is 3 The amount of water that dissolves at 40°C is 1.66 cm 3 ] at 20°C, whereas it is 2.58 [cm 3 ] and dissolves about three times as well. Therefore, by cooling the generated water W1 to 40° C. or less in the water cooler 23, the water-soluble poisonous substances can be efficiently adsorbed and removed.

[0020] Considering that the generated water W freezes at temperatures below 0°C, the temperature range realized by the water cooler 23 is 0 to 40°C. As can be seen from the graph in Fig. 2, the solubility of hydrogen sulfide increases as the temperature decreases under conditions of 0°C or higher, so it is more preferable that the temperature range of the generated water W1 is 3 to 30°C. Furthermore, it is more preferable that the temperature range of the generated water W1 is 5 to 20°C.

[0021] The produced water W2 that has become polluted water by containing water-soluble poisonous substances in the poisonous substance filter (filter portion) 16 is discharged from the drain pipe 35 through the housing 37 of the poisonous substance filter 16 (FIG. 3) to the outside of the system.

[0022] The produced water passage 14 is provided with a water storage section 22 and a water branch valve 26, for example a three-way valve. By adjusting the water branch valve 26 , a portion of the generated water W flowing through the generated water passage 14 is branched off into the water branch pipe 36 and supplied to the humidifier 19 .

[0023] The drain pipe 33, which is connected to the humidifier 19 and discharges the produced water W3, is provided with a back pressure valve 44 that is closed during pressurization by the compressor 17. Although not shown, the drain pipe 33 may be provided with a return pipe connected to the produced water passage 14. This is because the produced water W3 used in the humidifier 19 can be reused as cooling water or a wetting agent. On the other hand, if the produced water W2 that has become polluted by the poisoning substance filter 16 is used in the humidifier 19, water-soluble poisoning substances will flow into the fuel cell stack 11, poisoning the fuel cell stack 11, which is not preferable.

[0024] The water storage section 22 functions as a buffer tank that keeps the flow rate of the produced water W flowing into the poisoning substance filter 16 or the humidifier 19 constant. For example, immediately after the start of power generation, the fuel cell stack 11 does not produce enough water to supply to the poisoning substance filter 16 and the humidifier 19. Therefore, by storing water produced in the previous power generation in the water storage section 22, it is possible to supply the produced water W to the poisoning substance filter 16 and the humidifier 19 immediately after power generation is resumed. Also, by supplying water to the water storage section 22 in advance, it is possible to supply water to the poisoning substance filter 16 and the humidifier 19 immediately after power generation is started during a power generation test in the production factory.

[0025] Next, the poisoning substance filter 16 will be described with reference to a schematic perspective view of the poisoning substance filter 16 in FIG. The poisoning substance filter 16 is made of a water-absorbent or hydrophilic filamentous porous material, for example, as shown in Fig. 3, and is held upright in the housing 37. For example, as shown in Fig. 3, cylindrical gaps are provided at intervals in the porous material, allowing reaction air to flow through each cylinder.

[0026] An air inlet pipe 38 and an air outlet pipe (not shown) are connected to the housing 37 so that the reaction air α flows along the longitudinal direction of the poisoning substance filter 16. The air outlet pipe is connected to the compressor 17. With this structure, the reaction air α introduced into the housing 37 passes through the poisoning substance filter 16 and is then supplied to the compressor 17.

[0027] A water inlet passage 39 and a drain pipe 35 (FIG. 1) are connected to a side surface of the housing 37 along the longitudinal direction of the poisonous substance filter 16. The water inlet passage 39 is connected to the produced water passage 14 (FIG. 1). Furthermore, the impurity-dissolved water that flows down from the poisonous substance filter 16 is discharged at a constant rate to the outside of the housing 37 through a drain pipe 35 (FIG. 1).

[0028] As described above, according to the fuel cell system 100 of the first embodiment, the water-soluble poisoning substances can be efficiently dissolved by cooling the produced water W1 supplied to the poisoning substance filter 16. Moreover, the poisoning substances are dissolved in the produced water W1 and discharged to the outside of the system, and water not containing the water-soluble poisoning substances is continuously supplied to the poisoning substance filter 16. Therefore, the same poisoning substance filter 16 can be used for a long period of time. Moreover, since the produced water W1 supplied to the poisoning substance filter 16 is cooled, a large amount of water-soluble poisoning substances can be dissolved even in a compact system. In other words, according to the first embodiment, the poisoning substance filter 16 can be made compact and have a long life.

[0029] Second embodiment FIG. 4 is a schematic diagram of a fuel cell system 100 according to the second embodiment. FIG. 4 also shows an explanatory diagram of the humidifying filter 16a. FIG. 5 is an enlarged schematic cross-sectional view of a humidifying filter 16a in the second embodiment, cut along the flow direction of the reaction air α.

[0030] As shown in FIGS. 4 and 5, a fuel cell system 100 according to the second embodiment includes a filter unit 16 having a humidifying function 16a disposed inside the humidifier 19 shown in FIG. Further, a compressor 17 is provided in the supply passage 12 upstream of the humidifying filter 16a. The humidifying section 32 of the humidifier 19 humidifies the reacting air α by converting the generated water W3 into water vapor and releasing it. A plurality of filter sections 16 and humidifying sections 32 are arranged alternately in parallel. The humidifying section 32 is filled with, for example, a hollow fiber membrane material, and the filter section 16 is filled with, for example, a nonwoven fabric. The reacting air path 34 is formed as a gap between the humidifying section 32 and the filter section 16.

[0031] In the example of Figures 4 and 5, the flow positions of the produced water W1 and the reacted air α are reversed from those of the poisoning substance filter 16 of the first embodiment shown in Figure 3. However, the path through which the produced water W1 flows may be filled with, for example, a cylindrical filler and the reacted air α may flow through the gaps in this path, or the path through which the reacted air α flows may be filled with, for example, a cylindrical filler and the produced water W1 may flow through the gaps in this path. In addition, although the humidifying section 32 and the filter section 16 are cylindrical in FIG. 4, each of these cylinders may be formed so as to be wrapped around a metal support, for example.

[0032] As described in the first embodiment, the poisoning substance filter 16 is required to be supplied with low-temperature produced water W1. On the other hand, the humidifying section 32 is required to be supplied with higher-temperature produced water W3 in order to generate water vapor.

[0033] 4 and 5, the filter with humidification function 16a has a humidifier unit 32 and a filter unit 16 separated from each other, for example, in a manifold. The humidifier unit 32 is connected to a water branch pipe 36 and is supplied with humidification water W3 having a higher temperature than the filter unit 16. The filter section 16 is connected to a produced water passage 14a, through which the produced water W1 for filtering is supplied. The air inlet pipe 38 is connected to the compressor 17, and the reaction air α blown by the compressor 17 flows into the housing 37 through the air inlet pipe 38.

[0034] In this way, by isolating the generated water W3 for humidification and the generated water W1 for filtering at the inlet so that they do not mix with each other, the generated waters W1 and W3 having different temperatures can be passed through the humidifier section 32 and the filter section 16. Therefore, by providing the generated waters W1 and W3 at optimal temperatures to the internal devices 16 and 32 of the filter 16a with humidification function, respectively, it is possible to efficiently humidify and remove poisonous substances.

[0035] As described above, the filter units 16 and the humidifier units 32 are arranged alternately in multiple rows, and the reacting air α flows between them. Thus, the generated water W1, which is cooled and integrated with the humidifier 19, is supplied to the filter unit 16, so that the temperature of the reacting air α can be lowered. Since water of different temperatures is supplied to the filter unit 16 and the humidifier unit 32, the temperature rise of the reacting air α, which is compressed and blown out of the fuel cell system 100, is suppressed, so that the power generation efficiency of the fuel cell system 100 can be improved.

[0036] Furthermore, by providing the filter section 16 in the humidifier 19, the generated water W1 can be supplied to the filter section 16 at a high pressure from a low pressure location separate from the air flow of the compressor 17. As a result, the generated water W1 can be permeated into the filter section 16 without pressurizing it.

[0037] In the second embodiment, the compressor 17 is disposed upstream of the humidifying filter 16a, so that the humidifying filter 16a is subjected to pressure by the compressor 17. Therefore, in order to supply the produced water W1 to the filter section 16, a certain degree of pressurization is required. Therefore, in the discharge passage 13, it is desirable that the produced water passage 14 is provided upstream of the outlet valve 21. Then, when the produced water W is taken out, the outlet valve 21 is closed, and the produced water W at a pressure higher than the atmospheric pressure before being exhausted to the outside of the system is allowed to flow into the produced water passage 14. Since the solubility of gas is proportional to pressure, the high-pressure reactive air α passes through the filter section 16, so that the water-soluble poisonous substances can be efficiently dissolved, and the filter length of the humidifying filter 16a can be shortened. In addition, a mechanism for sending the produced water W1 is not necessary, so that the humidifying filter 16a can be made compact.

[0038] In addition, since the second embodiment has the same configuration as the first embodiment except that it is provided with the above-mentioned humidification filter 16a, that a compressor 17 is provided upstream of the humidification filter 16a, and that the generated water passage 14 is provided upstream of the outlet valve 21, a description thereof will be omitted. In the drawings, the same structures are designated by the same reference numerals, and corresponding structures are designated by reference numerals that differ only in alphabetical order, and the description thereof will be omitted.

[0039] As described above, according to the second embodiment, the humidifying filter 16a can be made compact, and power generation performance can be improved by adjusting the temperature. EXAMPLES

[0040] 6(A) to 6(C) are diagrams showing a model of a cylindrical air flow path 41 used in the examples. In the embodiment, the amount of hydrogen sulfide absorbed was evaluated by analysis when air containing hydrogen sulfide passes near a portion where moisture is present in a cylindrical air flow path 41 arranged in multiple layers as shown in Fig. 6(A). At this time, the distance between each air flow path 41 was set to 2R, which is the same as the diameter of the air flow path 41, as shown in Fig. 6(B).

[0041] In this model, it is assumed that when air enters the cylinder, hydrogen sulfide molecules diffuse to the inside surface of the cylinder and are absorbed by water. The equation that satisfies the concentration of hydrogen sulfide in the air entering the cylinder is formulated as the diffusion equation shown below (1).

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[0042] [Table 1] Moreover, the boundary conditions used in the numerical analysis of equation (1) are as shown in Table (2) below.

[0043] [Table 2]

[0044] Then, in order to numerically solve the partial differential equation of formula (1), each side was differentiated and numerical calculations were performed using the Euler method. In this case, it was discretized to satisfy the von Neumann stability condition of the following formula (2). Specifically, in order to satisfy formula (2), Nr = 50, Δz = 10 μm, and Δt = 0.02 μs were set in the differentiated formula (1).

number

[0045] Moreover, the discretized values ​​of the position and time in each direction are defined as in the following equations (3) to (5).

number

[0046] The distribution of the hydrogen sulfide concentration inside the poisoning substance filter was calculated assuming that the radius R of the air flow path 41 is 300 μm and the flow rate of the reaction air α is 200 NL / min. Figure 7 is a contour map showing the analysis result of the hydrogen sulfide concentration distribution inside the air flow path 41 in such a model. In FIG. 7, the horizontal axis represents the distance r [μm] from the central axis C, and the vertical axis represents the distance z [μm] from the inlet (see FIG. 6(C)).

[0047] In Fig. 7, at the inlet z = 0 mm of the poisoning substance filter, the initial concentration C is 4.1 [mmol / m 3 ], but the concentration decreases as the depth increases, and it can be seen that the hydrogen sulfide concentration is almost zero near the outlet at z = 5 mm. Also, near the inner surface of the cylinder in contact with water at r = 300 μm, the concentration decreased earlier than near the center.

[0048] Next, the distribution of hydrogen sulfide concentration in the cross section at a point 1 mm from the inlet was plotted on a graph as shown in FIG. The horizontal axis of Fig. 8 represents the distance r [μm] from the central axis C, and the vertical axis represents the hydrogen sulfide concentration C [mmol / m 3 8, it was confirmed that hydrogen sulfide is absorbed from the inner surface of the cylindrical air flow path 41, and therefore a concentration gradient is formed with respect to the distance r from the central axis C, and hydrogen sulfide is absorbed.

[0049] 8, it can be seen that the aperture of the poisoning substance filter 16 is preferably 50 μm to 500 μm. Taking into consideration the need to shorten the depth as much as possible, the aperture of the poisoning substance filter 16 is more preferably 100 μm to 400 μm, and further preferably 200 μm to 300 μm.

[0050] It was also confirmed that hydrogen sulfide was not yet sufficiently absorbed into the water at this 1 mm point. Therefore, an analysis was conducted using the radius R of the air flow path 41 as a parameter to determine how far from the inlet the hydrogen sulfide needs to penetrate to be sufficiently absorbed and the hydrogen sulfide concentration at the outlet sufficiently reduced.

[0051] Fig. 9 is a graph showing the results of analyzing the depth of the poisoning substance filter and the permeability of hydrogen sulfide by changing the flow path radius R of the air flow path 41. In Fig. 9, the flow path radius R of the air flow path 41 is changed to 100 μm, 200 μm, 300 μm, and 400 μm. In Fig. 9, the horizontal axis represents the depth of the poisoning substance filter, i.e., the thickness L [mm] in the direction of the reaction air flow, and the vertical axis represents the hydrogen sulfide permeability [%]. Note that the permeability here is defined as the ratio of the integrated outlet distribution to the inlet value.

[0052] From FIG. 9, it can be seen that when the flow path radius R is 100 μm, a poisoning substance filter thickness of 1 mm is sufficient to absorb hydrogen sulfide. As a standard, the depth of the poisoning substance filter when the hydrogen sulfide permeability is 5% was calculated and shown in FIG. The curves in the figure are the results of quadratic fitting of the plots using the least squares method.

[0053] From the above, it was found that in order for the poisoning substance filter to sufficiently block hydrogen sulfide, a minimum filter depth as shown in FIG. 10 is required, and this must be included as one of the conditions. The flow path radius R and the required filter depth calculated from the analysis are summarized in the following table (3). However, when the air velocity v is high, the depth L shown in table (3) needs to be longer in proportion to the velocity.

[0054] [Table 3] As described above, the embodiment allows the determination of the minimum shape (length and radius R of the poisoning substance filter 16 relative to the pore size of the poisoning substance filter 16) required to remove the water-soluble poisoning substances. Therefore, the poisoning substance filter 16 can be made compact.

[0055] The poisoning substance filter 16 absorbs hydrogen sulfide and also humidifies the air when it is dry. This allows the capacity of the humidifier 19 to be reduced, suppressing pressure loss after the compressor 17 increases pressure, and reducing energy loss.

[0056] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention.

[0057] For example, although the poisoning substance filter is an example of a filter made of aligned cylinders, a bubbling technique in which reactive air is released into water as bubbles may be used. Also, instead of bubbling reactive air into water, generated water may be sprayed into reactive air. In addition, a mechanism for removing water droplets contained in the reaction air may be provided between the upstream poisoning substance filter and the downstream compressor to protect the compressor from moisture. Furthermore, the techniques for removing water-soluble poisoning substances shown in each embodiment can also be applied to hydrogen. [Explanation of symbols]

[0058] 100... fuel cell system, 11... fuel cell stack, 12... supply path, 13... discharge path, 14... produced water passage, 16... poisonous substance filter (filter section), 16a (16)... filter with humidification function, 17... compressor, 18... air cooler, 19... humidifier, 20... inlet valve, 21... outlet valve, 22... water storage section, 23... water cooler, 24... bypass pipe, 25... bypass valve, 26... water branch valve, 32... humidification section, 33... drain pipe, 34... reaction air path, 35... drain pipe, 36... humidifier connection pipe, 37... housing, 38... air introduction pipe, 39... water introduction path, 41... air flow path, 44... back pressure valve, C... central axis, W (W1 to W3)... produced water, α... reaction air.

Claims

1. a fuel cell stack that generates electricity by reacting a fuel gas with an oxygen-containing gas; an exhaust passage for exhausting exhaust gas generated by power generation of the fuel cell stack to the outside of the system; a generated water passage for recovering generated water contained in the exhaust gas; a water cooler provided in the generated water passage and capable of cooling the generated water as needed; a filter section connected to the produced water passage downstream of the water cooler, the filter section using the produced water to remove water-soluble poisonous substances from the oxygen-containing gas attempting to flow into the fuel cell stack; a drain pipe connected to the filter section and used in the filter section to discharge the produced water containing the water-soluble poisonous substance to the outside of the system.

2. a compressor provided upstream of the filter unit in a supply path of the oxygen-containing gas; a humidifier having the filter unit disposed therein; 2. The fuel cell system according to claim 1, further comprising: a humidification section provided within the humidifier and connected to the generated water passage so as to receive the generated water at a higher temperature than the filter section.

3. 3. The fuel cell system according to claim 1, further comprising a water storage section provided in the produced water passage and supplying the produced water stored in the filter section.

4. A fuel cell system as described in claim 2, comprising: a water storage section provided in the generated water passage and supplying the generated water stored in at least one of the filter section and the humidification section.

5. 5. The fuel cell system according to claim 1, further comprising an outlet valve provided in the discharge path downstream of a connection with the generated water passage, the outlet valve being closed when the generated water is discharged to the generated water passage.

6. 6. The fuel cell system according to claim 1, wherein the reaction air passage of the filter portion has a diameter of 50 μm to 500 μm.

7. reacting a fuel gas with an oxygen-containing gas to generate electricity; Discharging exhaust gas generated by power generation in the fuel cell stack to the outside of the system; recovering generated water contained in the exhaust gas; A step of cooling the recovered generated water in a timely manner; supplying the cooled product water to a poisoning substance filter to remove water-soluble poisoning substances from the oxygen-containing gas flowing into the fuel cell stack by the poisoning substance filter; and discharging the produced water, which has been used in the poisoning substance filter and contains the water-soluble poisoning substances, to the outside of the system.

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