JP2007149630A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To well exhaust product water at an anode side of a fuel cell in a simple and low-cost structure without using a pump or the like, with very little drain of hydrogen as fuel outside the cell, and with drastic improvement of power generating efficiency and safety aimed at. <P>SOLUTION: Power generation of a fuel cell 1 is carried out with both a supply valve 7 of hydrogen at an anode-side upstream of the fuel cell 1 and a drain valve 16 at an anode-side downstream in a closed state, and after the inside of the fuel cells 1 and a vessel 17 communicated with the fuel cells 1 get into a state of reduced pressure, the supply valve 7 is opened to jet hydrogen into the fuel cells 1 in the reduced state, and the product water of the fuel cells 1 at the anode side is pushed out to the vessel 17 to exhaust it. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell system that generates electric power using an electrochemical reaction between hydrogen and oxygen, and more particularly, to discharge of generated water generated by the reaction.

  Conventionally, a fuel cell system mounted on a vehicle generates power using an electrochemical reaction between hydrogen and oxygen gas, as in a polymer electrolyte membrane type fuel cell, for example. In the reaction process, The water generated on the electrode side) is diffused back to the anode side (hydrogen electrode side) through the polymer electrolyte membrane and mixed.

  If the mixed product water is left on the anode side of the fuel cell, the product water accumulates and the hydrogen concentration gradually decreases. As a result, the power generation efficiency of the fuel cell decreases. Causes damage.

  Therefore, in this type of fuel cell, how to discharge the generated water on the anode side is one of the important issues.

  And most simply, the fuel cell anode side of the fuel cell system is configured as shown in FIG. 9A, and surplus fuel (hydrogen gas) is provided in the exhaust passage 2 downstream of the anode side of the fuel cell (FC) 1. It is conceivable to provide a normally-closed exhaust valve 3 that discharges water and to open the exhaust valve 3 to discharge the generated water on the anode side together with the surplus fuel to the outside of the battery.

  In FIG. 9A, 4 is a fuel tank, 5 is its main stop valve, 6, 7 and 8 are regulators and fuel provided in the anode upstream path 9 from the fuel tank 4 to the fuel cell 1. A hydrogen supply valve and a pressure sensor, the valves 3, 5, and 7 and the regulator 6 are shown in an open state, and black is shown in a closed state.

  Then, the high-pressure hydrogen gas that has passed through the main stop valve 5 of the fuel tank 4 is depressurized and adjusted by the regulator 6, and then passes through the supply valve 7 and the pressure sensor 8 from the anode side upstream to the downstream side of the fuel cell 1. In the meantime, an electrochemical reaction occurs between the hydrogen and oxygen (air) supplied to the cathode side of the fuel cell 1 through the polymer electrolyte membrane to generate electric power.

  However, in the case of the configuration shown in FIG. 9 (a), when the produced water of the anode is discharged from the exhaust valve 3 to the outside of the battery, a large amount of fuel hydrogen is also discharged from the exhaust valve 3, and so-called fuel loss is large. In addition, the concentration of hydrogen discharged outside the battery is high, and there is a risk of ignition, which is not practical.

  Further, the fuel cell anode side of this type of fuel cell system is configured as shown in FIG. 9B, and a fuel circulation path 10 is provided that returns from the anode side downstream of the fuel cell 1 to the anode side upstream. A dehydrator 11 for gas-liquid separation and a pump 12 for reflux are sequentially provided downstream of the anode side, a normally closed drain valve 14 is provided in the drain pipe 13 of the dehydrator 11, and the generated water of the anode of the fuel cell 1 is supplied. It can also be considered that the battery is separated by the dehydrator 11 and discharged from the drain valve 14 to the outside of the battery. In addition, the drain valve 14 is also in a state in which white is opened and in which black painting is closed.

  In this case, unreacted hydrogen downstream of the anode of the fuel cell 1 is returned to the anode upstream through the dehydrator 11 and the pump 12, and the generated water is stored in the lower part of the dehydrator 11 and drained at an appropriate timing. The dehydrator 11 is discharged by opening the valve 14. Therefore, the discharge of fuel hydrogen to the outside of the battery is less than in the configuration of FIG.

  However, in the case of the configuration shown in FIG. 9B, it is necessary to provide not only the dehydrator 11 but also a pump 12 including an electric pump that requires power and an ejector pump that is difficult to control, which is complicated and expensive. Further, in order to reduce the loss of the circulation path 10, it is necessary to increase the flow path cross-sectional area of the fuel cell 1.

Therefore, an air / water separator such as the dehydrator 11 is provided downstream of the anode side of the fuel cell, and a reaction inhibitor passage from the downstream side of the anode side to the upstream side of the cathode side of the fuel cell is provided. Oxidant) It is a reaction inhibitor on the anode side of the fuel cell by using the pressure difference between the downstream side of the anode side and the above-mentioned part on the cathode side by connecting to the upstream side (atmosphere side) part of the pump on the suction side It is proposed that the produced water is separated and discharged by a steam separator, and the produced water that has not been separated is discharged from the cathode side downstream. In this case, a polymer membrane, a porous body, etc. It has also been proposed to suppress the discharge of unreacted hydrogen by providing an adjusting means (see, for example, Patent Document 1).
JP-A-2005-203179 (abstract, [0010]-[0012], [0015]-[0025], [0056]-[0060], [0066]-[0069], FIG. 1 etc.)

  In the case of the conventional system of Patent Document 1, the generated water on the anode side of the fuel cell is discharged from the steam / water separator and the cathode side. Therefore, the discharge of fuel hydrogen is less than in the case of the configuration of FIG. It is safe. In addition, since the differential pressure between the anode side and the cathode side is used, a pump or the like is unnecessary, and it is simpler and less expensive than the configuration of FIG. 9B.

  However, the anode side downstream of the fuel cell always communicates with the cathode side via the reaction inhibitor path, and the unreacted hydrogen on the anode side easily flows out of the cell from the cathode side due to the pressure difference. There is a problem that power generation efficiency decreases due to loss.

  In addition, in order to reduce the fuel loss by providing the adjustment means in the reaction inhibitor path, it is necessary to provide not only a steam / water separator and reaction inhibitor path but also an adjustment means, resulting in a complicated configuration. Problems arise.

  The present invention has a simple and inexpensive configuration that does not use a pump or the like, so that the discharge of hydrogen as a fuel to the outside of the battery is extremely small, and the power generation efficiency and safety can be dramatically improved. The purpose is to discharge the generated water well.

  In order to achieve the above-described object, the fuel cell system of the present invention is a fuel cell system that generates power by supplying hydrogen to the anode side of the fuel cell and supplying air to the cathode side of the fuel cell. The hydrogen supply valve upstream of the anode side, a drain valve for discharging the generated water on the anode side of the fuel cell downstream of the anode side, and the fuel cell between the fuel cell and the drain valve A water reservoir for storing the generated water is provided, and after the power generation of the fuel cell is performed with the supply valve and the drain valve closed, the supply valve is opened to discharge the generated water. (Claim 1).

  In the fuel cell system of the present invention, when the wet state set on the anode side of the fuel cell is detected, the supply valve and the drain valve are closed to generate power in the fuel cell. (Claim 2).

  Furthermore, the fuel cell system of the present invention is configured to reduce and vary the volume of the water reservoir so as to suppress a change in the pressure of the fuel cell during power generation with the supply valve and the drain valve closed. It is characterized (claim 3).

  According to the first aspect of the present invention, when the produced water on the anode side of the fuel cell is discharged, the hydrogen supply valve and the produced water drain valve are closed so that the fuel cell stops supplying hydrogen as fuel. Then, this power generation causes the water reservoir portion communicating with the inside of the fuel cell and the fuel cell to be decompressed.

  Then, by opening the supply valve after the inside of the fuel cell is in a decompressed state, hydrogen is injected into the fuel cell in the decompressed state, and the generated water on the anode side of the fuel cell is pushed out to the water reservoir, and the outside of the cell Surely discharged.

  In this case, a pump, a dehydrator (steam separator), etc. are not required, and there is no need to provide a reflux system from the downstream on the anode side to the upstream on the anode side or to the cathode side. Is done.

  In addition, the downstream of the anode side of the fuel cell does not communicate with the cathode side, unreacted hydrogen on the anode side does not leak from the cathode side to the outside of the cell, and the hydrogen concentration discharged outside the cell is extremely low, It is safe and there is very little fuel loss, and the power generation efficiency is remarkably improved.

  Therefore, with a simple and inexpensive configuration that does not use a pump or the like, discharge of hydrogen as a fuel to the outside of the battery is extremely small, and the generation water on the anode side of the fuel cell is improved so as to improve power generation efficiency and safety. Can be discharged.

  According to the invention of claim 2, the retention state of the generated water on the anode side is grasped from the wet state on the anode side of the fuel cell, and the generated water on the anode side of the fuel cell is obtained when the retention state is appropriate. It can be discharged, and the power generation efficiency and safety are further improved.

  According to the invention of claim 3, during the power generation with the supply valve and the drain valve closed, the volume of the water reservoir is reduced and the pressure drop of the fuel cell due to the consumption of hydrogen as fuel is suppressed. The output voltage is prevented from lowering due to the pressure drop of the fuel cell. Therefore, the generated water on the anode side of the fuel cell can be discharged well so as to further improve the power generation efficiency.

  Next, in order to describe the present invention in more detail, the embodiment will be described in detail with reference to FIGS.

(One embodiment)
First, an embodiment will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a block diagram of the anode side of the fuel cell system, and FIG. 2 is an explanatory diagram of the generated water discharge process of FIG. 1. In these drawings, the same reference numerals as those in FIGS. 9A and 9B are the same or equivalent. 15 is an anode-side downstream path from the fuel cell 1 to the normally closed drain valve 16, and 17 is a rectangular box or cylindrical container of an appropriate size provided in the anode-side downstream path 16. The water reservoir of the present invention is formed. In FIGS. 1 and 2, the valves 5, 7, 16 and the regulator 6 are shown in a state in which white is opened and in a state in which black painting is closed.

  The fuel cell system of this embodiment is characterized in that a supply valve 7 is provided upstream of the anode side of the fuel cell 1, a container 17 and a drain valve 16 are provided downstream of the anode side, and the generated water on the anode side is provided. When the fuel cell 1 is discharged with the supply valve 7 and the drain valve 16 closed, the supply valve 7 is opened and the generated water is discharged. Is determined from the wet state on the anode side of the fuel cell 1, in other words, the accumulated state of the generated water on the anode side of the fuel cell 1, and the supply valve 7 is detected when the set wet state on the anode side of the fuel cell 1 is detected. The fuel cell 1 is configured to generate electricity with the drain valve 16 closed.

  Next, the generated water discharge process of the system of FIG. 1 will be described with reference to FIG.

  Step S1 in FIG. 2 shows a normal power generation state. In this normal power generation state, the supply valve 7 is opened, and the fuel cell 1 is connected from the fuel tank 4 via the regulator 6, the supply valve 7, and the pressure sensor 8. The hydrogen gas of fuel is supplied to the anode side.

  Then, the generated water that accompanies the power generation stays on the anode side of the fuel cell 1, the wet state on the anode side progresses, and the power generation capacity gradually decreases. The black portions of the fuel cell 1, the container 17 and the like in FIG. 2 are generated water schematically shown.

  Therefore, the wet state on the anode side of the fuel cell 1 is estimated or detected from a state value such as an integrated value, voltage, or power generation time of the current of the fuel cell 1, and the state value is set to a predetermined value set by an experiment or the like. When it reaches the timing at which the generated water needs to be discharged, the process proceeds to step S2 in FIG. 2, the supply valve 7 is closed, and the power generation of the fuel cell 1 is continued with the supply valve 7 and the drain valve 16 closed.

  At this time, the fuel cell 1 generates power with the supply of hydrogen gas as fuel stopped, and the power generation causes the inside of the fuel cell 1 and the container (water reservoir) 17 communicating with the fuel cell 1 to be in a decompressed state.

  Then, when the inside of the fuel cell 1 falls to a predetermined pressure or the current amount (integrated value) from the start of depressurization of the fuel cell 1 reaches a set value, the process proceeds to step S3 in FIG. Then, hydrogen gas is injected into the fuel cell 1 in a decompressed state, and the generated water on the anode side of the fuel cell 1 is pushed out into the container 17 by the hydrogen gas flow from the fuel cell 1 to the container 17 through the anode downstream path 15. Surely discharge outside the battery.

  At this time, in order to prevent the generated water in the container 17 from flowing back to the fuel cell 1, in this embodiment, the piping of the fuel cell 1 and the container 17 is connected to the upper part of the container 17, and the drain valve 16 is connected from the container 17. The pipe extending to is connected to the lower part of the container, and the generated water is dropped into the container 17 and stored. Instead of providing a step in the pipe on the fuel cell 1 side and the pipe on the drain valve 16 side of the container 7, for example, a reverse valve may be provided in the pipe between the fuel cell 1 and the container 17.

  Further, in order to surely discharge the generated water staying on the anode side of the fuel cell 1, the container 17 is made larger than the space volume on the anode side of the fuel cell 1, and all the fuel etc. on the anode side are all put into the container 17. The pressure may be reduced so as to be introduced, and the adjustment of the pressure reduction can be controlled by adjusting the generated power of the fuel cell 1. The pressure change ΔP and the generated current i are expressed as follows: ΔP = (R · T / V) × ((i / 96485) × (number of cells / 2)) where R, T, and V are gas multipliers, temperature, and volume. There is a relationship.

  Then, until a certain amount of generated water is accumulated in the container 17, the process returns from step S 3 to step S 1 to perform normal power generation. When the generated water needs to be discharged, the process proceeds to steps S 2 and S 3 and the above processing is repeated. return.

  Further, when a certain amount of generated water accumulates in the container 17, the process proceeds from step S3 to S4 in FIG. 2, the drain valve 16 is opened, the stored water in the container 17 is discharged, and the drain valve 16 is closed after the drainage is completed. And it returns to process S1. The drain valve 16 is formed of an electromagnetic valve similar to the supply valve 7 or the like, or a float type valve.

  As described above, in the fuel cell system of this embodiment, the pump 12, the dehydrator 11, the fuel circulation path 10 and the like shown in FIG. 9B are unnecessary, and the downstream side of the anode side to the cathode side are also provided. There is no need to provide a reaction inhibiting substance route or the like that reaches the upstream side, and the water formed on the anode side of the fuel cell 1 can be discharged simply and inexpensively. Further, the downstream side of the anode side of the fuel cell 1 does not communicate with the cathode side, unreacted hydrogen on the anode side does not leak from the cathode side to the outside of the cell, and water has accumulated in the container 17 to some extent. Since the downstream drain valve 16 is opened, the hydrogen gas concentration discharged to the outside of the battery is extremely low and extremely safe, the fuel loss is extremely low, the power generation efficiency is remarkably improved, and the simple and inexpensive configuration is used. The generated water on the anode side of the fuel cell 1 can be discharged well so as to improve the power generation efficiency and safety.

  Furthermore, since the retention state of the generated water on the anode side is grasped from the wet state on the anode side of the fuel cell 1 and the generated water on the anode side of the fuel cell 1 is discharged when the appropriate retention state is reached, The generated water on the anode side of the fuel cell 1 is discharged only when necessary, and the power generation efficiency and safety are further improved.

(Other embodiments)
Next, another embodiment will be described with reference to FIGS.

  FIG. 3 is a block diagram on the anode side of the fuel cell system, and the same reference numerals as those in FIG. 1 denote the same or corresponding components. 4 is an explanatory view of the operation of the accumulator 19 in FIG. 3, FIGS. 5 and 6 are examples of the accumulator 19, and other examples. FIGS. 7 and 8 are fuel cell actuators that can be used as a drive source of the accumulator 19. FIG. It is a block diagram of an example and other examples.

  In the case of the configuration of the embodiment of FIG. 1, if power generation is continued with the supply valve 7 and the drain valve 16 closed based on the detection of the wet state on the anode side of the fuel cell 1, the inside of the fuel cell 1 As the remaining hydrogen is consumed, the internal pressure of the fuel cell 1 decreases, and the output voltage decreases as the pressure decreases, leading to a decrease in power generation efficiency.

  Therefore, in this embodiment, as shown in FIG. 3, a water tank 18 with an accumulator 19 is provided instead of the container 17 of FIG.

  This water tank 18 forms a water reservoir. Further, the accumulator 19 is internally or externally mounted on the water tank 18 and is a bellows type combining a bellows and a spring, a bladder type provided with a rubber balloon (bag), a piston type, a diaphragm type, or the like. This is a well-known structure.

  When power generation is continued with the supply valve 7 and the drain valve 16 closed based on detection of the wet state of the anode side of the fuel cell 1, the pressure inside the fuel cell 1 according to the consumption of residual hydrogen during the power generation. The pressure inside the water tank 18 communicating with the anode side of the fuel cell 1 also starts to drop, but at this time, the accumulator 19 responds to the reduced pressure of the water tank 18, and the diaphragm as the partition wall of the accumulator 19 is The volume (volume) of the water tank 18 decreases due to the expansion to the decompression side, the balloon inflates, or the piston operating, and the pressure drop in the water tank 18 and the fuel cell 1 is prevented or alleviated (suppressed). Is done.

  Therefore, a decrease in power generation efficiency due to a decrease in the output voltage of the fuel cell 1 during that period is prevented, and the power generation efficiency is improved as compared with the case of one embodiment.

  Then, a predetermined time elapses from the start of depressurization of the fuel cell 1 based on power generation in a state where the supply valve 7 and the drain valve 16 are closed, or the current amount (integrated value) from the start of depressurization reaches a set value. Then, the supply valve 7 is opened to discharge the generated water.

  At this time, the fuel cell 1 and the water tank 18 communicating with the anode side thereof are in a depressurized state as will be described later, and hydrogen gas is injected into the fuel cell 1 as in the case of the embodiment, The generated water on the anode side of the fuel cell 1 can be pushed out to the water tank 18 by the hydrogen gas flow reaching the water tank 18 via the anode-side downstream path 15 and reliably discharged outside the cell.

  The water accumulated at the bottom of the water tank 18 is then discharged from the water tank 18 by opening the drain valve 16.

  Therefore, in the case of this embodiment, the generated water on the anode side of the fuel cell 1 can be discharged well so as to further improve the power generation efficiency.

  Next, the operation of the accumulator 19 will be described with reference to FIG.

(I) When the accumulator 19 is not provided (in the case of FIG. 4A)
In this case, the power generation with the supply valve 7 and the drain valve 16 closed consumes (1/2) · n0 of hydrogen in the number of moles as shown in FIG. Is reduced from the pressure P0 before the start of power generation (before consumption) to the pressure P1 at the end of power generation (at the end of consumption), the volume of the water tank 18 remains unchanged at V0, so P0 · V0 = n0 · R · From the relationship of T (Equation 1), P1 · V0 = (1/2) · n0 · R · T (Equation 2), P1 = (1/2) · P0 (Equation 3). ), (Expression 3), P1 = (1/2) · P0 (Expression 4) is obtained, and the pressure P1 becomes 1/2 of the original pressure P0.

  Therefore, when the accumulator 19 is not provided, power generation is performed with the supply valve 7 and the drain valve 16 being closed, and, for example, half the number of moles of hydrogen in the fuel cell 1 and the water tank 18 in communication are consumed. The pressure of 1 (= pressure of the water tank 18) is reduced to half of the original pressure.

(Ii) When the accumulator 19 is provided (in the case of FIG. 4B)
For simplicity of explanation, as shown in FIG. 4B, it is assumed that the accumulator 19 is a piston type that partitions the water tank 18 into upper and lower two chambers A and B by a movable partition 19a having an area S.

  At this time, the chamber A corresponds to the accumulator 19, the chamber B corresponds to the water tank 18, and before the start of power generation (before consumption), the chambers A and B are both filled with hydrogen having a pressure P0 and a volume V0 and a molar number n0. As shown on the left side of FIG. 4 (b), the opposite forces F = P0 · S shown in the up and down arrows are applied to the movable partition 19a having the area S from the chambers A and B.

  Then, due to the power generation with the supply valve 7 and the drain valve 16 closed, (1/2) · n0 of hydrogen is consumed in the number of moles of the chamber B as in the case where the accumulator 19 is not provided, and the chamber B is pressurized. When the pressure changes to P1, the movable partition 19a moves downward as shown on the right side of FIG. 4B, the volume of the chamber B decreases by ΔV, and the volume of the chamber A increases by ΔV. They are balanced in the state where forces F = P1 · S acting in opposite directions are applied.

  At this time, for the chamber A, P1 · (V0 + ΔV) = n0 · R · T (Expression 5), and for the chamber B, P1 · (V0−ΔV) = (1/2) · n0 · R · T (Expression 6), and ΔV = (1/3) · V0 (Expression 7) is obtained from the relationship between these expressions. Further, from Formula 5 and Formula 1, P0 · V0 = P1 · (V0 + ΔV) (Formula 8). Then, P0 · V0 = P1 · (V0 + ΔV) (Equation 9) is obtained from Equations 7 and 8, and P1 = (3/4) · P0 (Equation 10)) from Equations 7 and 9. Thus, the pressure P1 becomes 3/4 of the original pressure P0.

  Therefore, when the accumulator 19 is provided, the fuel cell is generated by generating power with the supply valve 7 and the drain valve 16 closed and consuming, for example, half the number of moles of hydrogen in the water tank 18 connected to the fuel cell 1. The pressure of 1 (= pressure of the water tank 18) is 3/4 of the original.

  As is clear from a comparison between the above formula (i) 4 and formula (ii) 10 and the like, when, for example, half the number of moles of hydrogen is consumed by power generation with the supply valve 7 and the drain valve 16 closed, When the accumulator 19 is not provided, the pressure of the fuel cell 1 (= pressure of the water tank 18) is ½ of the original. When the accumulator 19 is provided, the volume of the water tank 18 can be changed through the volume change of the fuel cell 1. The volume decreases and the pressure of the fuel cell 1 (= pressure of the water tank 18) becomes 3/4 of the original, and the pressure drop of the fuel cell 1 is suppressed (relaxed).

  As a result, a decrease in the power generation efficiency due to the pressure decrease in the state where the supply valve 7 and the drain valve 16 are closed is prevented, and the power generation efficiency of the fuel cell 1 is improved.

  Even if the accumulator 19 is provided to suppress (relieve) the pressure drop of the fuel cell 1, the fuel cell 1 and the water tank 18 that communicates with the fuel cell 1 are not connected to the power supply when the power generation is completed with the supply valve 7 and the drain valve 16 closed. The pressure is further reduced and the pressure is reduced.

  Therefore, when the power generation in the state where the supply valve 7 and the drain valve 16 are closed and the supply valve 7 is opened, hydrogen gas is injected into the fuel cell 1 and passes through the anode downstream path 15 from the fuel cell 1. Thus, the generated water on the anode side of the fuel cell 1 can be pushed out to the water tank 18 by the hydrogen gas flow reaching the water tank 18 and discharged outside the cell.

  The same applies when the accumulator 19 is a diaphragm or a balloon.

  By the way, by opening the supply valve 7, regardless of the presence of the accumulator 19, the fuel cell 1 and the water tank 18 connected to the fuel tank 1 return to the original pressure state due to the amount of hydrogen consumed by power generation. Specifically, for example, when (1/2) · n0 moles of hydrogen is consumed by power generation in a state where the supply valve 7 and the drain valve 16 are closed, the presence or absence of the accumulator 19 is established by opening the supply valve 7. Regardless, (1/2) · n0 moles of hydrogen flows in, so that the fuel cell 1 and the water tank 18 communicating with the fuel cell 1 return to the original pressure state.

  The pressure and flow rate of the injected hydrogen gas affect the discharge of the produced water on the anode side of the fuel cell 1, and when the accumulator 19 is provided, the same amount of hydrogen gas is communicated with the fuel cell 1 when the accumulator 19 is not provided. When the supply valve 7 and the drain valve 16 are closed and the supply valve 7 is opened when the supply valve 7 and the drain valve 16 are closed, the pressure of the hydrogen gas to be injected is higher than that in the above embodiment. Although weak, the flow rate of hydrogen gas does not change, and the generated water on the anode side of the fuel cell 1 can be pushed out to the water tank 18 and reliably discharged outside the cell.

  When the supply valve 7 is opened, the diaphragm, balloon, piston, etc. are instantaneously returned to their original state by the action of an external force, which will be described later, and the volume of the fuel cell 1 and the water tank 18 in communication are rapidly increased. If the water tank 18 is in a sufficiently reduced pressure state, the power generation efficiency of the fuel cell 1 can be improved and the generated water on the anode side of the fuel cell 1 can be discharged more reliably to the outside of the cell.

  Next, a specific example of the accumulator 19 will be described.

<Example of accumulator>
First, in the case where the accumulator 19 is a bladder type built in the water tank 18 and has the rubber-like balloon 20 shown in FIGS. 5A and 5B, the hydrogen having the pressure P0, the volume V0, and the number of moles n0 described above. A balloon 20 filled with a gas having a constant pressure corresponding to is provided in the container of the water tank 18 as shown in FIG. 5A, and expands and contracts according to the external pressure, that is, the pressure change of the water tank 18, The volume (volume) of the water tank 18 is varied to prevent or moderate the pressure change.

  By the way, in a normal power generation state in which fuel hydrogen gas is supplied from the fuel tank 4 to the anode side of the fuel cell 1 through the regulator 6, the supply valve 7, and the pressure sensor 8, the fuel tank 1 communicated with the anode side of the fuel cell 1. The water tank 18 tends to be pressurized, and the balloon 20 is kept relatively small as shown in FIG.

  Next, when the fuel cell 1 generates power with the supply valve 7 and the drain valve 16 closed based on the detection of the wet state of the anode side of the fuel cell 1, the water tank is accompanied by a decrease in the internal pressure of the fuel cell 1. 18 starts to decrease in pressure and is in a depressurized state. At this time, as shown in FIG. 5B, the balloon 20 expands and increases, the volume of the water tank 18 decreases and decreases, and the fuel cell 1 Is suppressed (relaxed) and the power generation efficiency is improved.

  When the power generation is finished and the supply valve 7 is opened to discharge the generated water, the fuel cell 1 and the water tank 18 are in a depressurized state, and hydrogen gas is injected into the fuel cell 1 so that the fuel cell 1 and the water are discharged. Hydrogen gas flows into the tank 18, the pressure of the water tank 18 rises, the balloon 20 rapidly collapses and the volume of the water tank 18 increases, and the fuel cell 1 and the water tank 18 are further decompressed. Therefore, hydrogen gas can be injected into the fuel cell 1 without applying an external force, and the generated water on the anode side of the fuel cell 1 can be discharged well.

  When the balloon 20 expands in a state where the upper part of the water tank 18 and the lower part connected to the anode side of the fuel cell 1 are hermetically partitioned as shown in FIG. When the supply valve 7 is opened to discharge water, the pressure of the lower portion is increased by hydrogen gas, the balloon 20 is deformed, and a gap is formed in the partition between the upper portion and the lower portion. The volume of the water tank 18 communicated with the anode side of the fuel cell 1 through the lower part increases rapidly, and the fuel cell 1 and the water tank 18 are further reduced in pressure. Therefore, in this case, hydrogen gas can be injected into the fuel cell 1 without applying an external force, and the produced water on the anode side of the fuel cell 1 can be discharged more reliably.

  Next, when the fuel cell 1 is maintained at the same pressure as usual by reducing the volume of the water tank 18 and the power generation efficiency is further improved, for example, a balloon is provided outside the water tank 18 via an on-off valve mechanism. A negative pressure vessel (not shown) communicated with 20 is provided, and the on-off valve mechanism is opened only when the supply valve 7 is opened to discharge generated water.

  In this case, when the supply valve 7 is opened, the opening / closing valve mechanism is opened, and the gas in the balloon 20 flows into the negative pressure vessel, the balloon 20 is suddenly deflated, and the volume of the water tank 18 is rapidly increased, and the fuel cell 1. And the pressure of the water tank 18 decreases rapidly. Therefore, the fuel cell 1 and the water tank 18 are further depressurized, and the produced water on the anode side of the fuel cell 1 can be more reliably discharged by the sufficient pressure and flow rate of hydrogen gas.

<Other examples of accumulator>
Next, when the water tank 18 is made of, for example, a cylindrical stainless steel (non-magnetic material) and the accumulator 19 is a piston type built in the water tank 18, for example, as shown in FIG. The water tank 18 has a tank portion 22 communicating with the fuel cell 1 below the piston plate 21 and a piston plate by a magnetic piston plate 21 that slides up and down (corresponding to the operation partition 19a in FIG. 4). 21 is hermetically partitioned into the upper piston portion 23, and the volume of the tank portion 22 is the volume of the water tank of the present invention. Note that an O-ring 24 is attached to the peripheral portion of the piston plate 21 in order to improve airtightness.

  Moreover, the lower end of the coil-shaped spring 25 is attached to the upper surface of the piston plate 21, and the upper end of the spring 25 is supported, for example, at the center of the top plate of the water tank 18.

  Then, based on detection of the wet state of the anode side of the fuel cell 1 and the like, the fuel cell 1 generates power with the supply valve 7 and the drain valve 16 closed, and the water tank 18 is reduced as the internal pressure of the fuel cell 1 decreases. When the pressure of the tank portion 22 begins to drop, the piston plate 21 moves downward, the volume of the tank portion 22 decreases, and the pressure drop of the fuel cell 1 and the water tank 18 in communication is prevented or alleviated.

  Further, when the supply valve 7 is opened to discharge the generated water, the fuel cell 1 and the water tank 18 are in a decompressed state, hydrogen gas is injected into the fuel cell 1, and hydrogen gas is injected into the fuel cell 1 and the water tank 18. Can flow in and the hydrogen gas can be injected into the fuel cell 1 without any external force, and the water produced on the anode side of the charging cell 1 can be discharged well.

  By the way, when discharging the generated water on the anode side of the battery 1 more reliably, for example, an electromagnet (not shown) is placed on the top plate of the water tank 18 and the supply valve 7 is opened to discharge the generated water. When the electromagnet is energized, the piston plate 21 is instantaneously pulled up by the magnetic force, the volume of the tank portion 22 is rapidly increased, the fuel cell 1 and the water tank 18 are further depressurized, and the anode side of the fuel cell 1 is The generated water is more reliably discharged with sufficient pressure and flow rate of hydrogen gas.

  The piston plate 21 may be moved up and down using the spring 25 or an electromagnet instead of filling the piston portion 23 with gas or liquid and adjusting the filling pressure. You may carry out by using.

  The reduction in the pressure reducing container in the example and the increase / decrease in the filling pressure in the other example can be performed using, for example, a compressor, and the pressure of fuel hydrogen or oxidant (air) is used for pressurization. It is also possible.

  Furthermore, an actuator (fuel cell actuator) described next to another separately provided fuel cell can be used to change the volume of the water tank 18.

<Fuel cell actuator>
Next, the fuel cell actuator will be described with reference to FIGS.

  This fuel cell actuator uses a change in pressure of a fuel cell system that generates electricity using gas as fuel, and is formed, for example, in the configuration shown in the example of FIG.

  In FIG. 7, 100 is a fuel cell actuator, 101 is its fuel cell, 102 is a hydrogen gas fuel supply device (fuel tank) on the anode side of the fuel cell 101, and corresponds to the fuel tank 4 of FIG. The fuel cell 101 is connected by an anode-side upper flow path 104 provided with a quantity adjusting device 103. Here, the fuel supply amount adjusting device 103 includes, for example, an injector for adjusting a pressurizing force, an electromagnetic valve, or a pressure regulating valve.

  Reference numeral 105 denotes an anode-side lower flow path connected to the anode-side upper flow path 104 via the fuel cell 101, and 106 denotes a power take-out piston mechanism, which includes an exterior body 107 and a piston 108 that can move in and out of the exterior body 107. And a mild cylinder portion (space) 109 between the inner surface of the exterior body 107 and the piston 108 is connected to the open end portion of the anode-side lower flow path 105.

  During the power generation of the fuel cell 101, the fuel supply amount adjusting device 103 intermittently increases or decreases the supply of the hydrogen gas to the fuel cell 101, so that the pressure of the fuel cell 101 due to the intermittent or increased supply of the hydrogen gas is increased. 7 is used to move the piston 108 in the direction of the arrow in FIG. 7 by using the increase / decrease change in the cylinder unit 109, and various uses of other devices such as the variable power of the volume of the water tank 18 in FIG. It can be taken out as motive power (kinetic energy). The adjustment of the hydrogen gas supply amount of the fuel is controlled according to, for example, the measured pressure value or estimated pressure value of the fuel cell 101 or the operation amount of the piston 108 which is the operation amount of the actuator.

  Therefore, it is possible to take out a change in pressure generated by the power generation of the fuel cell 101 as power and effectively utilize the change in pressure to realize variable control of the volume of the water tank 18 in FIG.

  Next, FIG. 8 shows another example of the fuel cell actuator, in which the same reference numerals as those in FIG. 7 denote the same or corresponding elements.

  In the fuel cell actuator 100b of FIG. 8, the fuel cell 101 is mounted on the bottom plate 107a of the exterior body 107 of the piston mechanism 106, and the anode side 101A of the fuel cell 101 penetrates the bottom plate 107a of the exterior body 107 in an airtight manner. The anode-side lower flow path 105 shown in FIG. 7 is omitted from the cylinder portion 109 in the body 107.

  Further, the fuel supply amount adjusting device 103 of the anode-side upper flow path 104 connected to the fuel supply apparatus 102 penetrates the peripheral portion 107b of the exterior body 107 in an airtight manner, and its output side is inserted into the cylinder portion 109. The open end portion of 104 is connected to the anode side 101 </ b> A of the fuel cell 101 through a cylinder portion 109. Note that 101N is the cathode side of the fuel cell 101, and 110 is an O-ring at the base of the piston.

  Also in the case of this fuel cell actuator 100b, during the power generation of the fuel cell 101, the fuel supply amount adjusting device 103 intermittently increases or decreases the supply of the hydrogen gas of the fuel to the fuel cell 101, and the pressure change due to the power generation of the fuel cell 101 Is used to vary the pressure of the cylinder portion 109, and the piston 108 is moved up and down in the direction of the arrow in FIG. Energy).

  Specifically, for example, the piston 108 is pushed down by pressurizing the supply pressure of the hydrogen gas supplied from the fuel supply device 102 to the fuel cell 101 via the cylinder 109 by the fuel supply amount adjusting device 103, and then the hydrogen gas The cylinder 109 is depressurized by the power generation of the fuel cell 101 in a state where the supply of fuel is stopped or reduced, the piston 108 is pulled up, and the piston 108 is moved up and down in the direction of the arrow in FIG. The power (kinetic energy) for various applications of other devices such as variable volume power can be extracted.

  In a system that generates power by rotating an impeller using a fuel gas intake airflow, if the gas flow is used effectively, pressure loss in the impeller increases. However, the fuel cell actuator described above uses gas as fuel. The pressure change of the fuel cell system that generates electricity is used as power, and there is an advantage that the problem of pressure loss in the impeller does not occur.

  And this invention is not limited to each above-mentioned embodiment, It is possible to perform various changes other than what was mentioned above, unless it deviates from the meaning, For example, the container 17, Instead of providing the water tank 18, for example, the pipes of the container 17 and the water tank 18 in the anode downstream path 15 may be thickened. Further, the number of cells of the fuel cells 1 and 101 may be whatever.

1 is a block diagram of a fuel cell system according to an embodiment of the present invention. It is explanatory drawing of the generated water discharge process of FIG. It is a block diagram of the fuel cell system of other embodiment of this invention. (A), (b) is explanatory drawing of an effect | action of the accumulator of FIG. It is explanatory drawing of an example of the accumulator of FIG. 3, (a) shows a normal electric power generation state, (b) shows the state of pressure reduction. It is explanatory drawing of the other example of the accumulator of FIG. It is a block diagram of an example of the fuel cell actuator which can be used for the drive source of the accumulator of FIG. FIG. 4 is a block diagram of another example of a fuel cell actuator that can be used as a drive source for the accumulator of FIG. 3. (A), (b) is a block diagram of an example of a conventional system and another example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101 Fuel cell 4 Fuel tank 7 Supply valve 16 Drain valve 17 Container (water reservoir)
18 Water tank (water reservoir)
19 Accumulator

Claims (3)

In the fuel cell system for generating power by supplying hydrogen to the anode side of the fuel cell and supplying air to the cathode side of the fuel cell,
The hydrogen supply valve is provided upstream of the anode side,
A drain valve for discharging the generated water on the anode side of the fuel cell downstream of the anode side;
A water reservoir for storing the generated water of the fuel cell between the fuel cell and the drain valve;
The fuel cell system, wherein the fuel cell is generated with the supply valve and the drain valve closed, and then the supply valve is opened to discharge the generated water. The fuel cell system according to claim 1, wherein
A fuel cell system, wherein when the set wet state on the anode side of the fuel cell is detected, the fuel cell is configured to generate electricity with the supply valve and the drain valve closed. The fuel cell system according to claim 1 or 2,
A fuel cell system, wherein the volume of the water reservoir is reduced and varied so as to suppress a change in pressure of the fuel cell during power generation with the supply valve and the drain valve closed.

Images