JP2014049344A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely exhaust moisture reverse-spread to an anode chamber from a cathode chamber during power generation with a simple structure, in a passive type fuel cell system.SOLUTION: A plurality of fuel cell modules 100a, 100b are electrically parallel-connected to a load. A fuel gas is distributed to each of the fuel cell modules 100a, 100b from a fuel source 300. A common gas-liquid separating part 200 is connected to the anode chamber of each of the plurality of fuel cell modules 100a, 100b. The load can be cutoff individually from each of the fuel cell modules 100a, 100b. In such a structure, during operation of the fuel cell system, after the output of a specific fuel cell module 100a, 100b is cutoff from the load or reduced, it is again connected.

Description

  The present invention relates to a fuel cell system.

  The fuel cell system is a device that generates electrical energy from hydrogen and oxygen, and can achieve high power generation efficiency. The main features of the fuel cell system are direct power generation that does not go through the process of thermal energy or kinetic energy as in the conventional power generation method, so that high power generation efficiency can be expected even on a small scale, and emissions of nitrogen compounds, etc. There are few, and noise and vibration are also small, and environmental properties are good. In this way, the fuel cell system can effectively use the chemical energy of the fuel and has environmentally friendly characteristics, so it is expected as an energy supply system for the 21st century, from space use to automobiles and portable devices. It is attracting attention as a promising new power generation system that can be used in various applications from large-scale power generation to small-scale power generation, and technological development is in full swing toward practical use.

  Fuel cell systems are roughly classified into an active type having an auxiliary machine such as a fuel supply pump and a passive type having no auxiliary machine.

JP 2006-164942 A

  In the conventional passive type fuel cell system, it is difficult to discharge the generated water out of the anode chamber when the generated water back-diffused from the cathode to the anode side during power generation stays in the anode chamber. As a result, when the fuel cell system is operated for a long time, the generated water hinders the diffusion of the fuel gas, and power generation may become unstable.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a passive fuel cell system that can reliably discharge moisture that has been reversely diffused from the cathode to the anode chamber during power generation with a simple configuration. Is in the provision of.

  One embodiment of the present invention is a fuel cell system. A plurality of fuel cell modules electrically connected in parallel with the load, a fuel storage unit for storing fuel supplied to the fuel cell module, and an anode chamber of the plurality of fuel cell modules from the fuel storage unit A fuel gas flow path for distributing the fuel, a common gas-liquid separator connected to each anode chamber, and a plurality of shutoffs capable of shutting off electrical connection between the load and each fuel cell module. A plurality of output adjusting units capable of reducing the output of each of the fuel cell modules and the output, and shutting off or reducing the output from at least one of the fuel cell modules to the load using the shut-off unit or the output adjusting unit. And a control unit that is connected or restored.

  According to the present invention, in a passive fuel cell system, moisture that has been back-diffused from the cathode to the anode chamber during power generation can be reliably discharged with a simple configuration.

1 is a perspective view showing an external appearance of a fuel cell system according to Embodiment 1. FIG. FIG. 2A is an enlarged perspective view showing the appearance of the fuel cell module. FIG. 2B is a cross-sectional view of the fuel cell module along the line AA in FIG. It is a figure which shows typically the electrical wiring and gas piping of a fuel cell system. It is a schematic diagram which shows the mechanism in which a water | moisture content is discharged | emitted from the anode chamber of a fuel cell module. FIG. 6 is a perspective view showing an appearance of a fuel cell system according to Embodiment 2.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

(Embodiment 1)
FIG. 1 is a perspective view showing an appearance of a fuel cell system 10 according to Embodiment 1. FIG. The fuel cell system 10 includes a fuel cell module 100, a gas-liquid separator 200, a fuel source 300, and a controller 400. The fuel cell system 10 according to the present embodiment is a passive fuel cell system that does not have auxiliary equipment such as a fuel supply pump.

  In the present embodiment, four fuel cell modules 100 are arranged in a plane on both main surface sides of a flat rectangular parallelepiped fuel source 300. It arrange | positions above the control part 400 so that the main surface of each fuel cell module 100 arranged planarly may become parallel to a perpendicular direction. The fuel source 300 can be pulled out upward, and can be removed as needed during replacement or refueling.

  FIG. 2A is an enlarged perspective view showing the appearance of the fuel cell module 100. FIG. 2B is a cross-sectional view of the fuel cell module 100 along the line AA in FIG. The fuel cell module 100 has a plurality of membrane electrode assemblies 110. The plurality of membrane electrode assemblies 110 are arranged in openings formed in the base material 120 and are arranged in a plane. The base material 120 is formed of an insulating material such as polyacrylate, for example.

  The membrane electrode assembly 110 includes an electrolyte membrane 130, a cathode 140 provided on one surface of the electrolyte membrane 130, and an anode 150 provided on the other surface of the electrolyte membrane 130. The electrolyte membrane 130 is provided so as to fill the opening provided in the base material 120. Air is supplied to the cathode 140 as an oxidant. On the other hand, hydrogen gas is supplied as fuel gas from the fuel source 300 to the anode 150 via the distribution manifold 500. A cell is configured by sandwiching the electrolyte membrane 130 between the pair of cathodes 140 and the anode 150, and each cell generates power by an electrochemical reaction between hydrogen and oxygen in the air.

  The interconnector 160 is provided through the base material 120 between the adjacent membrane electrode assemblies 110. In the adjacent membrane electrode assembly 110, the cathode 140 of one membrane electrode assembly 110 is connected to one end of the interconnector 160, and the anode 150 of the other membrane electrode assembly 110 is connected to the other end of the interconnector 160. Yes. The interconnector 160 is made of a conductive material such as carbon. With the above configuration, the adjacent membrane electrode assemblies 110 are connected in series by the interconnector 160.

  The electrolyte membrane 130 preferably exhibits good ion conductivity in a wet state, and functions as an ion exchange membrane that moves protons between the cathode 140 and the anode 150. The electrolyte membrane 130 is formed of a solid polymer material such as a fluorine-containing polymer or a non-fluorine polymer, and for example, a sulfonic acid type perfluorocarbon polymer, a polysulfone resin, a perfluorocarbon polymer having a phosphonic acid group or a carboxylic acid group. Etc. can be used. Examples of the sulfonic acid type perfluorocarbon polymer include Nafion (manufactured by DuPont: registered trademark) 112. Examples of non-fluorine polymers include sulfonated aromatic polyetheretherketone and polysulfone.

  Cathode 140 and anode 150 have ion exchange resin and catalyst particles, optionally carbon particles. The ion exchange resin that the cathode 140 and the anode 150 optionally have has a role of connecting the catalyst particles and the electrolyte membrane 130 and transmitting protons therebetween. This ion exchange resin may be formed of the same polymer material as the electrolyte membrane 130. Examples of catalyst metals include Sc, Y, Ti, Zr, V, Nb, Fe, Co, Ni, Ru, Rh, Pd, Pt, Os, Ir, alloys selected from lanthanoid series elements and actinoid series elements, A simple substance is mentioned. When the catalyst is supported, acetylene black, ketjen black, carbon nanotubes or the like may be used as the carbon particles.

  The fuel cell module 100 is disposed such that the cathode 140 side faces the outside of the fuel cell system 10 (the side opposite to the fuel source 300). In addition, the fuel cell module 100 includes a cathode protective layer 142 on the cathode 140 side of the membrane electrode assembly 110. The cathode protective layer 142 is a member located on the outermost side of the fuel cell module 100 on the cathode side. The cathode protective layer 142 is formed of a flat member, and the cathode protective layer 142 has a plurality of through holes 144 penetrating from one main surface to the other main surface. These through holes 144 provide air permeability between the cathode 140 and the outside of the fuel cell. The material of the cathode protective layer 142 is not particularly limited, and examples thereof include insulators such as anodized aluminum and polyacrylate. The cathode protective layer 142 may be formed in multiple layers such as a grill and a porous sheet. A gas-liquid separation membrane 146 is provided between the cathode protective layer 142 and the cathode 140. The gas-liquid separation membrane 146 has a function of allowing air taken in from the outside of the fuel cell and vapor generated at the cathode 140 to pass therethrough and blocking condensed water adhering to the cathode protective layer 142. Examples of the gas-liquid separation membrane 146 include Teflon (registered trademark).

  The periphery of the substrate 120 is fixed to the anode housing 156 via a gas seal 122. The gas seal 122 improves the airtightness between the anode chamber 152 formed between the anode housing 156 and the membrane electrode assembly 110 and the outside on the cathode side.

  A fuel flow path plate 170 having a fuel distribution flow path 172 is provided on the surface of the anode housing 156 opposite to the membrane electrode assembly 110. The flow path inlet 174 of the fuel distribution flow path 172 is connected to the fuel source 300 through the distribution manifold 500. A through hole 158 that connects the fuel distribution channel 172 and the anode chamber 152 is formed in the region of the anode housing 156 facing the fuel distribution channel 172, and the hydrogen supplied to the fuel distribution channel 162 The gas flows into the anode chamber 152. Further, a fuel outlet 159 is formed in the anode housing 156 in the vicinity of the flow path inlet 174, and the anode chamber 152 communicates with a gas-liquid separator 200 described later via the fuel outlet 159.

  Returning to FIG. 1, the gas-liquid separation unit 200 includes a gas chamber 210 and a gas-liquid separation membrane 220, and moisture contained in the off-gas supplied to the gas chamber 210 is absorbed by the gas-liquid separation membrane 220, Separated from. The gas-liquid separation membrane 220 is not particularly limited as long as it is a water-absorbing material. For example, Nafion (registered trademark) or sponge can be used.

  The gas chamber 210 of the gas-liquid separator 200 is connected to the anode chamber 152 of each fuel cell module 100. Moisture contained in the off gas discharged from the anode chamber 152 of each fuel cell module 100 is absorbed by the gas-liquid separation membrane 220 and separated from the off gas.

  In the present embodiment, the gas-liquid separation unit 200 extends so that the longitudinal direction thereof is in the horizontal direction, and two fuel cell modules 100 are arranged with the gas-liquid separation unit 200 interposed therebetween. A distribution manifold 500 is arranged so as to overlap the gas-liquid separation unit 200. Thereby, the projected area of the fuel cell system 10 in the plane in which the fuel cell modules 100 are arranged in a plane can be reduced, and the fuel cell system 10 can be made compact. Further, since the flow path from each fuel cell module 100 to the gas-liquid separator 200 can be shortened, pressure loss at the outlet portion of the anode chamber 152 of the fuel cell module 100 can be suppressed.

The fuel source 300 contains a hydrogen storage alloy. The hydrogen storage alloy can store hydrogen and release the stored hydrogen, for example, rare earth-based MmNi _4.32 Mn _0.18 Al _0.1 Fe _0.1 Co _0.3 (Mm is Misch metal). The hydrogen storage alloy is not limited to a rare earth alloy, and may be, for example, a Ti—Mn alloy, a Ti—Fe alloy, a Ti—Zr alloy, a Mg—Ni alloy, a Zr—Mn alloy, or the like. Good. Specifically, mention may be made of LaNi ₅ alloy, Mg 2 Ni _{alloy, Ti 1 + x Cr 2-} y Mn y (x = 0.1~0.3, y = 0~1.0) and an alloy as a hydrogen absorbing alloy . The hydrogen storage alloy can be formed into a compression molded body (pellet) obtained by mixing a binder such as polytetrafluoroethylene (PTFE) dispersion into the above-mentioned hydrogen storage alloy powder and compression molding with a press. A regulator (not shown) is provided between the fuel source 300 and the distribution manifold 500, and the gas pressure in the anode chamber 152 is kept constant by adjusting the opening of the regulator. The fuel source 300 is not limited to the MH cartridge shown in the embodiment, but reforms a liquid fuel such as methanol or a gas fuel such as butane to generate hydrogen, or promotes generation and generation of a hydrogen generating material. In the case of generating a combination of substances, it can be applied as long as the fuel gas can be supplied at a predetermined pressure, such as when stored in a high-pressure cylinder.

  FIG. 3 is a diagram schematically showing the electrical wiring and gas piping of the fuel cell system 10. As shown in FIG. 3, the hydrogen gas supplied from the fuel source 300 is evenly distributed to the fuel cell modules 100 by the distribution manifold 500. Specifically, the distribution manifold 500 includes a first flow path 510 directly connected to the fuel source 300, a second flow path 520 having the same pipe diameter branched from the first flow path 510 into two systems, and each second flow. The piping system branched into two lines from the path 520 has the same third flow path 530.

  The anode chamber of each fuel cell module 100 is connected to a common gas-liquid separator 200. Note that the gas chamber 210 of the gas-liquid separation unit 200 is kept in an airtight state so that gas does not leak out of the system.

  Each fuel cell module 100 is electrically connected in parallel to the load. Specifically, the anode 150 of each fuel cell module 100 is connected to a positive-side common line 620 that is connected to the positive terminal 610 of the load 600 via a switch or output adjusting unit 20. Further, the cathode 140 of each fuel cell module 100 is connected to a negative common line 640 that is connected to the negative terminal 630 of the load 600. In this manner, the output of the fuel cell module 100 can be individually cut off or reduced from the load 600 by turning off or adjusting the switch or the output adjustment unit 20.

  FIG. 4 is a diagram schematically showing a mechanism for discharging moisture from the anode chamber 152 of the fuel cell module 100. In FIG. 4, for the sake of simplification of explanation, a case where the number of fuel cell modules 100 is two and a switch that cuts off the output of the fuel cell module 100 from a load is illustrated.

First, as shown in FIG. 4I, hydrogen gas having a pressure of 50 kPa is supplied from the fuel source 300 to the fuel cell modules 100a and 100b. At this time, the pressures P _1o and P _2o on the downstream side of the anode chamber 152 of the fuel cell modules 100a and 100b become 45 kPa due to pressure loss.

Next, as shown in FIG. 4 (ii), the fuel cell module 100b is disconnected from the load. In this state, hydrogen gas is not consumed in the fuel cell module 100b. For this reason, the pressure P _1o is 45 kPa, while the pressure P _2o is 50 kPa.

Next, as shown in FIG. 4 (iii) and FIG. 4 (iv), the gas is _discharged from the anode chamber 152 of the fuel cell module 100b so that the pressure P _2o and P _x2 of the gas-liquid separator 200 become the same pressure. Gas movement toward the liquid separation unit 200 occurs. Along with this gas movement, the produced water staying in the anode chamber 152 of the fuel cell module 100b is discharged from the anode chamber 152 and moves to the gas-liquid separator 200. The generated water that has moved to the gas-liquid separator 200 is separated from the gas phase.

Next, as shown in FIG. 4 (v), after a predetermined time has elapsed since the fuel cell module 100b was disconnected from the load, the fuel cell module 100b is connected to the load. Thereby, hydrogen gas is consumed in the fuel cell module 100b, and the pressure P _2o becomes 45 kPa.

Next, as shown in FIG. 4 (vi), a gas flow from the gas-liquid separator 200 to the anode chamber 152 of the fuel cell module 100a occurs so that the pressure _Px1 and the pressure _P1o are equal. Also, so that the pressure _{P x2} and pressure _{P 2o} equal, the flow of gas from the gas-liquid separator 200 to the fuel cell module 100b of the anode chamber 152 occurs.

Next, as shown in FIG. 4 (vii), when the pressure P _x1 and the pressure P _1o become equal and the pressure P _x2 and the pressure P _2o become equal, the gas flow from the gas-liquid separation unit 200 stops. .

  In summary, when the load of one fuel cell module that is in steady operation is cut off, the consumption of fuel in that fuel cell module stops, and the internal pressure of the anode chamber of the corresponding fuel cell module increases. As a result, gas movement to the gas-liquid separation unit 200 provided downstream of the anode chamber occurs, and generated water in the anode chamber is discharged to the gas-liquid separation unit using this gas movement.

  That is, the generated water staying in the anode chamber 152 of the fuel cell module 100 can be discharged out of the anode chamber 152 without using power. In addition, since the gas chamber 210 and the anode chamber 152 of the gas-liquid separation unit 200 are kept in an airtight state, the generated water staying in the anode chamber 152 of the fuel cell module 100 is discharged to the anode without releasing hydrogen to the outside. It can be discharged outside.

  Examples of the operation mode with the output of the specific fuel cell module cut off or reduced from the load include at least the following two modes.

(Mode for determining a fuel cell module that stops power generation according to the amount of water remaining in the anode chamber)
In this aspect, the fuel cell module 100 further includes a moisture content acquisition unit (not shown) that acquires information related to the moisture content in the anode chamber. In addition to a method for directly detecting the amount of moisture in the anode chamber 152, the moisture amount acquisition unit detects the output voltage, current, temperature, internal pressure, and the like of each fuel cell module 100 to thereby determine the moisture in the anode chamber 152. A method of obtaining the amount indirectly may be employed. In this aspect, the control unit 400 cuts off or reduces the output to the load in the manner shown in FIG. 4 for the fuel cell module 100 for which the above-described water content is determined to be equal to or greater than a predetermined value. Reconnect or return. In the method of indirectly obtaining the moisture content, an increase in the moisture content can be predicted by a decrease in output current and output voltage and an increase in variation of each fuel cell module 100, an increase in temperature and internal pressure, and an increase in variation. More specifically, the output current of each fuel cell module 100 is detected, and when the output current of a specific fuel cell module 100 falls below a predetermined threshold voltage, the output of the fuel cell module 100 is cut off from the load. Or reduce. According to this, it is possible to appropriately perform the water discharge process on the fuel cell module 100 that needs to discharge water.

  Alternatively, the output voltage of the membrane electrode assembly 110 connected in series in each fuel cell module 100 is detected, and the output voltage of the membrane electrode assembly 110 in the specific fuel cell module 100 becomes equal to or higher than a predetermined threshold voltage. If the output voltage variation of the membrane electrode assembly 110 exceeds a predetermined threshold value, the output of the fuel cell module 100 is cut off or reduced from the load. According to this, it is possible to appropriately perform the water discharge process on the fuel cell module 100 that needs to discharge water.

(Mode for switching fuel cell modules that stop power generation at predetermined time intervals)
In the present embodiment, the control unit 400 selects the fuel cell module 100 to be controlled from a plurality of fuel cell modules 100 in a predetermined order, and the selected fuel in the manner shown in FIG. After the output of the battery module 100 is cut off or reduced from the load, it is reconnected or restored. According to this, moisture can be discharged from the anode chamber 152 with a simpler configuration.

  In this embodiment, one fuel cell module is cut off from the load. However, two or more fuel cell modules can be removed from the load at the same time as long as the conditions for causing gas transfer from the anode chamber to the gas-liquid separator 200 are satisfied. You may block it. However, in order to cause sufficient gas movement to discharge generated water, when the number of fuel cell modules is n, the number m of fuel cell modules simultaneously cut off from the load satisfies m ≦ n / 2. It is preferable to satisfy.

  Further, by reducing the number of fuel cell modules that stop power generation by being cut off from the load with respect to the number of fuel cell modules that are generating power, the low-pressure region including the gas-liquid separation unit 200 and the anode chamber can be reduced. The volume difference from the high-pressure region that is included can be further increased. For this reason, the amount of gas transfer from the fuel cell module 100 that stops power generation to the gas-liquid separator 200 can be increased, and moisture can be discharged more reliably from the anode chamber 152.

  According to the fuel cell system 10 described above, it is possible to reliably discharge the moisture diffused back from the cathode 140 to the anode chamber 152 during power generation without using power. As a result, even when the fuel cell system 10 is operated for a long period of time, it is possible to suppress the diffusion of the fuel gas by the generated water staying in the anode chamber 152, so that power generation can be stabilized.

  In the present embodiment, as shown in FIG. 1, the gas-liquid separation unit 200 and the distribution manifold 500 are arranged so that the longitudinal directions thereof are oriented in the horizontal direction. You may arrange | position so that a longitudinal direction may face a perpendicular direction.

(Embodiment 2)
FIG. 5 is a perspective view showing an appearance of the fuel cell system 10 according to Embodiment 2. FIG. In this Embodiment, it arrange | positions so that the longitudinal direction of the gas-liquid separation part 200 may face a perpendicular direction. The distribution manifold 500 is formed on both sides of the fuel cell system 10, and two fuel cell modules 100 are disposed between one distribution manifold 500 a and the gas-liquid separation unit 200, and the other distribution manifold. Two other fuel cell modules 100 are arranged between 500 b and the gas-liquid separator 200. By arranging the gas-liquid separation unit 200 and the distribution manifold 500 in this way, the fuel cell system 10 can be thinned. Further, as in the first embodiment, since the flow path from each fuel cell module 100 to the gas-liquid separation unit 200 can be shortened, pressure loss at the outlet portion of the anode chamber 152 of the fuel cell module 100 is suppressed. be able to.

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added based on the knowledge of those skilled in the art. The form can also be included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Fuel cell system, 100 Fuel cell module, 110 Membrane electrode assembly, 120 Base material, 130 Electrolyte membrane, 140 Cathode, 150 Anode, 152 Anode chamber, 200 Gas-liquid separation part, 300 Fuel source, 400 Control part, 500 Distribution Manifold

Claims (3)

A plurality of fuel cell modules electrically connected in parallel with the load;
A fuel storage unit for storing fuel supplied to the fuel cell module;
A fuel gas flow path for distributing the fuel from the fuel storage section to the anode chambers of the plurality of fuel cell modules;
A gas-liquid separator connected to each anode chamber;
A plurality of shut-off parts capable of shutting off the electrical connection between the load and each fuel cell module, respectively, or a plurality of output adjusting parts capable of reducing the output, respectively;
A control unit for reconnecting or returning after shutting off or reducing output from at least one of the fuel cell modules to the load using the shutoff unit or the output adjustment unit;
A fuel cell system comprising:   The control unit selects a fuel cell module to be controlled from the plurality of fuel cell modules according to a predetermined order and disconnects the connection between the selected fuel cell module and the load. The fuel cell system according to claim 1, wherein the fuel cell system is reconnected. A water content acquisition unit that acquires information on the water content in the anode chamber of each fuel cell module;
2. The fuel cell system according to claim 1, wherein the control unit reconnects the fuel cell module for which the moisture content is determined to be greater than or equal to a predetermined value after disconnecting the connection with the load.

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